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MineFire Pro+ USER`S MANUAL & TUTORIAL

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1. Dn wgl Methane Concentration Warning Criteria fj Fume Concentration Warning Criteria 0 05 X High Temperature Warning Criteria f 00 EI Boundary Range for Fan Curves Extend by following gradients of two ends Extend left boundary by following gradient and set right boundary gradient to zero Set gradient of both sides of boundary region to zero Cancel Help Figure 29 Control Card II dialogue box 5 6 MineFire Contaminants A MineFire Contaminant is added by using the Fan Tool button or by selecting Contaminants from the MineFire menu then choosing Add Contaminant from the new Contaminants menu bar item This will bring up the screen seen in Figure 30 The parameters are discussed in Section 3 7 Properties of a contaminant may be edited by either of these two steps also however a contaminant may only be removed by selecting Delete Contaminant from the Contaminants Menu and picking the item from the spreadsheet view 47 MineFire Contaminants E From n gt To DR Description Cancel Flow Rate 0 cfm Concentration 0 zz Heat Transfer 0 btu min 02 Concentration 0 zz Contaminant Production 0 per ft 3 of Heat Production 0 btu Reference Q 0 cfr Lead Time 0 min Figure 30 MineFire Contaminants Screen 5 7 Modeling Stench Gas To model stench gas or a similar type of scenario the user enters the flow rate and concentration parameters
2. y 0 0015x 2 4282x 120 degree Celcius 200 300 400 cubic meters per ton Figure 35 Gas emission versus temperature for wood SI Amount of gas emitted by combustion of 1 ton of wood ata given temperature y 8 6565x 247 19x 248 4 6 8 cubic feet per pound Figure 36 Gas emission versus temperature for wood Imperial 56 Run a MineFire model using the Heat Transfer parameter calculated above and the Reference Q and assumed Lead Time values Find the Avg Temp value in the fire branch at the end of the lead time period this value can be used to represent the temperature variable in the gas emission formulas for wood fires in Figure 35 and Figure 36 above For this calculation we will assume that our performance of this procedure resulted in a temperature of 1000 C Solve the polynomial y 1000 0 0015x 2 4282x 120 Or 0 0 0015x 2 4282x 880 x 548 or 1048 m ton 550 m ton 9 71 f gas Ib wood According to Speight from 11 wood emits 25 CO at any temperature above 400 C SO 9 71 ft gas Ib wood x 25 2 43 ft CO Ib wood Max burn rate from above 137 5 Ib wood min Max emission rate 137 5 Ib wood min x 2 43 ft CO Ib wood 334 cfm CO Using the assumption that the fire is burning in one compartment Emission rate 31 ft x20 ft perim of 1 compartment x0 0047 ft minx17 58 Ib ft x 2 43 ft CO Ib wood 124 cfm CO
3. Stop After Steady State Network balance calculations Number of Fans Number of Contamination Sources Stop after Steady State Temp and Concentration calcs Max Iterations in Temperature Part C Skip Temp output during non steady state calculations MFire Output e Brief Set Defaults Normal C Detail C More Detailed Max Iterations in Dynamic Part Time Increment in Dynamic Part Time Span of Dynamic Simulation ALL Time Interval for Output Reference Temperature of Air 0 Degrees E Reference Density Ibm ft 3 Figure 5 MineFire Control Card I Screen Branches Fans and Contamination Sources These three parameters are fixed at this time within the program The number of Branches is limited to 3 500 fans are limited to 70 and contamination sources to 70 Max Iterations in Temperature Part This is the maximum number of iterations allowed in the steady state portions of simulation the Initial Time 0 and Quasi equilibrium assumed steady state ventilation system phases The default value is 20 Max Iterations in Dynamic Part This is the maximum number of iterations allowed in the dynamic non steady state portion of the simulation where the fire is affecting the ventilation system over time and the user can view fume fronts and the changing parameters on the schematic Again the default is set to 20 Time Increment in Dynamic Part This is the time increment used in the non stead
4. 23 5 Ib min CO Flowrate of CO 23 5 Ib min CO 0 075 Ib ft3 314 cfm CO 61 In the fuel rich case Contaminant Production equals volume of contaminant gas per volume of oxygen delivered to the fire 1100 cfm x 21 231 cfm O2 Contaminant Production 314 cfm CO 231 cfm O 1 36 f f O To determine the flowrate and concentration variables in an oxygen rich fire consider one of the other branches with airflow 58 300 cfm Assume the fire is 50 over ventilated 58 300 cfm 150 x 0 075 Ib ft3 x 21 612 Ib min O2 available for combustion Determine oxygen needed to burn Carbon component 612 Ib min O2x0 669 IbC Ib coalx11 6 Ib air IbC 10 0 Ib air Ib coal 475 Ib min O2 Find the mass flowrate of CO assumes CO CO efficiency 100 475 Ib min O x 3 12 CO 1 78 O2 832 Ib min CO Determine flowrate 832 Ib min O 0 075 Ib ft3 11 100 cfm CO Determine concentration 11 100 cfm 58 300 11 100 16 0 CO Note that the concentration value of 16 assumes 100 carbon combustion efficiency and 100 efficiency in the conversion of CO to CO 4 Determine the oxygen consumed by the combustion of coal Use the oxygen rich case w airflow of 58 300 cfm C 05 gt CO Mass of C 0 669 Ib Ib coal S 05 gt SO Mass of S 0 035 Ib Ib coal H 4 O2 gt H20 Mass of H 0 056 Ib Ib coal Assume that the reaction C CO gt 2CO Takes preference over the reaction C 14 03 gt CO Above 400
5. 6 4 VEMGEE FIRE EXAMPLE uio cs ect EE TA ER AL T 64 7 APPENDIX A TOOLS AND TOOL BUTTONS ssssscsssssccssssccccssscccssssccccssssccscssseecessceccssnee 70 8 APPENDIX B HEAT TRANSFER SAMPLE CALCULATION ee eene ee een eee ento eee etnu 72 9 APPENDIX C CALCULATING AIR FUEL RATIO eee ee eee eerte eee eo nose ee tn sese ta tos e etta a 73 10 APPENDIX D TABLE OF HEAT RELEASE VALUES 4 eere ee eese en eee en toes to sese ense eta 75 11 APPENDIX E WOOD WEIGHTS AND HEAT VALUES eee ee eren ee eee enne ee to sese ee tn sesta 76 12 APPENDIX F TABLE OF CONVERSION FACTORS BETWEEN IMPERIAL AND SI UNE NEE 77 D APPENDIX G REFERENCES n cisssesssscsssccssssvesssiescecssveticesvesasesussessesssosieessesbssvesscosssedssndsscodeviecsosse 81 List of Figures Figure 1 Model Information View envrrnvvnvnvnnvnnnrarvrarenssenrnsnrnsnvnsnvnsnvnnnnensnenenrernensvraserassvsssvssenee 13 Figure 2 MineFire Branch Data View sees eene rennen rennen 15 Figure 3 MineFire Average Values Screen eene 17 Figure 4 MineFire Junction Data View 18 Figure 5 MineFire Control Card I Screen 20 Figure 6 MineFire Control Card II Screen 21 Figure 7 Output detaining critical conditions eese ener 23 Figure 8 MineFire Time Ta ble e e eR ee he e iiaeaa 24 Figure 9 MFite Fire Event Symbol tnter etre teet ee tiere ta 26 Figure 1
6. On the Control Card II screen the Temperature at Start Junction parameter should be as close to true average outside air temperature as possible to obtain accurate results The Start Junction must also be entered The Calculation Accuracy Parameters will have an effect on overall precision but also affect simulation run time if that is a concern The control card parameters are further discussed in section 3 45 Control Cards MFire Control Data MFire Control Card II Number of Branches r Select Calculations Morber ct Farm hay 2 Complete Al ee Number of Contamination Sources e s f n E e n i i ETE i B t on cal Max Iterations in Temperature Part bu Skip Temp output during non steady state calculatio Max Iterations in Dynamic Part 20 MFire Output Time Increment in Dynamic Part 30 i l l Time Span of Dynamic Simulation 5 9 ote Time Interval for Output 1 C More Det Reference Temperature of Air 75 F Reference Density 0 074 lb f Cancel App Help Figure 28 Control Data I dialogue box 46 Control Cards MFire Control Data MFire Control Card II Starting Junction Atmosphere il Set Defaults Temperature at Start Junction ei EE Fa Time Span to assume Quasi equilibrium fi 0 Hours Accuracy in Fume Calculation 0 005 X Accuracy in Methane Calculation Dm Accuracy in Temperature Calculation jor IF Pressure Drop Warning Criteria Dm
7. The simulated fire is placed low in the intake shaft between junctions 33 and 30 as shown The fire is assumed to be 50 over ventilated 150 of oxygen necessary for combustion is provided by the airflow Shaft compartments are lined in dry white pine lumber 3 plank and there is 280 ft of timber exposed between each steel set 5 feet 6 sets Shaft segments are 300 feet long The average air density was determined from measured data to be 0 0833 Ib ft Figure 34 Wood Shaft Mine Example Data for White Pine Dry Data for White Pine Wet Weight per Cord Heating Value Weight per Cord Heating Value 2250 Ib 8044 Btu Ib 3240 Ib 5339 Btu Ib Note 1 cord 128 ft Values taken and converted from the table in Appendix E 54 1 Determine Heat Transfer Reference Q 15 000 cfm from branch 33 30 Determine the heat basis of the fire 15 000 cfm x 21 O5 3 150 cfm O2 3 150 cfm O x 0 0833 Ib ft 262 Ib min O3 At 50 over ventilated 262 Ib min O2 150 175 Ib min O2 Available for combustion At 50 excess air 9 09 lbs of air to burn 1 Ib of wood fuel Max burn rate 15 000 cfm x 0 0833 Ib ft x 1 Ib wood fuel 9 09 Ib air 137 5 Ib fuel min Max Heat Transfer 137 5 Ib fuel min x 8044 Btu Ib 1 106 000 Btu min Density of White Pine 2250 Ib 128 ft 17 58 In Volume available to burn 280 ft x 0 25 ft x 300 ft 5 ft 4200 fr Weight available to burn 4200 f x 17 58 Ib ft
8. and Ref Q and Lead time if needed for the branch or branches in question Other parameters are left blank 5 8 Executing the Simulation The MineFire simulation is executed by accessing the Execute MineFire kernel option under the MineFire menu The mfire tmp text file will open automatically with the output if any errors occurred during the run The text output can be accessed from the MFire results option in the MineFire Menu 5 9 Viewing Results The results of a simulation may be viewed graphically or in text format Both have their uses The Schematic View will display the resulting values of the simulation upon execution of the MineFire kernel The Initial Data Phase shows the data prior to the initiation of a fire or event The Non Steady State Data Phase allows the user to scroll through the results of the dynamic simulation and view the data and progression of the fume front s in the user selected time increment and duration entered in the Control Cards It includes a symbol showing the location of the fire or event and symbols for the contaminant smoke front as it progresses through the mine An example is shown in Figure 31 The Quasi Equilibrium Phase displays the ventilation network data at the end 48 of the dynamic simulation based on the assumptions the user entered in the Control Cards It is assumed that this amount of time is sufficient for the forces in the system to balance out Checking the text fil
9. junction numbers airway total resistance airflow pressure drop air power branch description and a symbol indicating whether the branch contains a fan regulator or booster fan The output sheet is designed such that it is easy to read and simple to scroll through 4 4 4 Fan Operating Points The Fan Results View lists the output operating points for the fan s in the model It gives the operating pressure airflow parallel series configuration required power annual operating cost and a description of the fan 4 4 5 Fixed Quantity Information Fixed quantity input and output data are shown under the Fixed Quantity View This view lists branch number junction From To the booster pressure the regulator resistance the regulator orifice area the input branch resistance the total resistance of the branch if regulated and the description for the branch 4 4 6 Printing Output Data The output data tabular views and the schematic can be directly printed by either clicking the print icon on the tool bar or by selecting the Print Active View subheading under the File Menu Printing plotting DXF file generation and formatting are discussed in great detail in sections 4 4 and 4 5 of the VnetPC Pro User s Manual 5 Tutorial For additional information on the many tools and features mentioned in this section refer to the previous sections in this document and the program Help Tools 5 1 Introduction This tutorial desc
10. 5 000 branches 4 000 junctions and 1000 fans or fixed quantities These limits should allow enough versatility for most mine ventilation simulations 3 Data Preparation and Input A model or simulation will only be as good as the user inputs and since fire is such a difficult thing to predict that makes the modeler s job that much harder The user must design credible fire scenarios to model a burning LHD in a shop a shaft fire with wood compartments burning and so on A number of decisions are necessary in order to define what type of fire is being simulated what variables must be used in the fire simulation and how the variables are to be used Many of these decisions are in the realm of engineering judgment some guidelines and suggestions are provided in the form of variable descriptions tables for heats of combustion calculation procedures etc but decisions regarding the fire scenario are the responsibility of the engineer performing the modeling Some decisions that an engineer will have to make will include the following e What is burning Wood diesel fuel coal a piece of equipment The engineer will have to make judgments as to the amount s of fuel available types and average heat of combustion e Is the fire oxygen rich or fuel rich A fire will be oxygen rich when in areas of moderate or high airflow The Concentration Heat Transfer and O Concentration variables will be used for fire input A fire may shift
11. 854 0 979 0 979 0 000 0 000 14 960 22 854 135 48 504 72 10 000 cfm air Os rich Flowrate CO cfm 56 695 0 000 162 236 55 852 0 000 83 323 3 719 3 719 0 000 0 000 55 852 83 323 504 72 Oxygen concentration 5 67 O 10000 cfm 0 075 0 21 4 22 IbO Ibf 27 28 Ibf min 157 5 115 42 5 10 075 lb ft 566 67 10 000 cfm Weight of rubber equivalent in fire 1 760 Ib Weight of diesel equivalent in fire 1 257 Ib Calculated values Rubber Diesel Weighted Average Heat Transfer 757 510 528 948 662 282 Btu min CO Flowrate 720 504 7 630 3 cfm CO Concentration 7 2 5 05 6 30 O2 Concentration 5 73 5 67 5 71 Contaminant Prod 0 47 0 361 0 425 FCI O2 69 7 Appendix A Tools and Tool Buttons The following list is a description of the buttons and tools available in the Schematic View bk aa fe amp Selection Pointer Zoom In Out Zoom All Create Junction Create Branch Fan or Fixed Q Contaminant Create Label Zoom Eraser Edit 3 D Spin Tool Cross Section Long Section Plan View Active Group This button selects branches and is the default mode The user can drag and drop existing junctions using this tool It also has right button mouse features for editing objects These two buttons zoom in and out as referenced from the center of the schematic shown on the screen They are useful to apply when the Zoom Tool is not active but the user still wishes to zoom in or
12. C This assumption from 11 simplifies the calculations Determine the oxygen consumed by each reaction C 0 669 Ib x 32 g mol O2 12 g mol C x 1 mol O 1 78 Ib O2 S 0 035 Ib x 32 g mol O2 32 g mol S x 1 mol O 0 035 Ib O 62 Ho 0 056 Ib x 32 g mol O2 2 g mol H2 x 0 5 mol O2 0 448 Ib O2 Total O2 consumed 2 26 Ib Ib coal Mass flowrate of O2 oxygen rich case 58 300 cfmx21 x0 075 Ib ft3 918 Ib O2 min Burn rate 294 6 Ib coal min So The oxygen consumed in combustion is 294 6 lb coal min x 2 26 Ib O2 Ib coal 666 Ib O2 min New oxygen mass flowrate in air exhausting fire area 918 Ib O2 min 666 Ib O2 min 252 Ib O2 min Volume flowrate 252 Ib O gt min 0 075 Ib ft 3360 cfm O2 Assume Qi Qo so Qo 58300 cfm assumption validated in Example 6 2 Oxygen concentration 3360 cfm O 58300 cfm 5 896 63 6 4 Vehicle Fire Example Assume a piece of diesel powered equipment catches fire The machine and area it is located in have the following characteristics e 4x400 Ib tires e 100 gallon fuel tank e assume oxygen rich airflow Ref Q 10 000 cfm e assume fuel rich airflow 1 100 cfm e Pair 0 075 Ib ft Properties Heat value tires 14 015 Btu Ib Heat value diesel 19 390 Btu lb Heat value hydraulic 13 400 Btu Ib P diesel 61 Ib ft Weight of each component Tires 4x400 Ib 1600 Ib Diesel 100 gal x 0 134 ft gal x 61 Ib ft 817 4 Ib Th
13. E Li i I stress 47 880 1 tie 6894 76 249 089 g 2989 07 immwg 9 807 L 1 80 0003346 ftw g 010197 mmwg 00002953 inHg 1 0 007501 mmHg Note The millibar 1 mb 100 N m2 is included here as it is a familiar metric unit of pressure Itis not however an SI unit Ns2 m 1 Ns2 m8 16 747 8 N 0 8942 s2 m8 Ns2 m 3386 39 0 059 71 resistance Airway 22 366 specific resistance Friction 1 Ibf min2 ft4 1 8554 x 106 Factor 16 018 5 KI P kom kom 0 06243 1043 70 000753 imp ton yd3 Lon n 1 short 1186 55 ton yd3 E RR od a 1055 06 0 000948 Btu 4 186 8 Jo 0 23889 cal 105 506 MJ 70009478 1Bu dca Atherm Wo 1W gt 1 ftlbfimin 0 0226 WW 44 254 filbfimn 1Btwmin 17 584 W AJ 0 056 87 Bumm 1RT 3517 Ww 0 000 2843 RT Refrigeration imp ton Energy work heat 78 Imperial to S SI to Imperial cn Specific 2 989 H Jikg energy ne bet DE aka E ton LET MJ kg 8 602 utherm sho ton rt ton Gas 1 ft Ibf lb R Jikg K 1 J kg K 0 1859 ft Ibf lb R constants Specific heat 1 Btu lb R 4186 8 Jikg K 1 J kg K 0 000 2388 Btu lb R Specific entropy EB a iR co s e volume TT ef ton ton u NENNEN viscosit stokes Ho i Thermal E ft ft2 h 1 730 73 Wim K 1 WmK 0 577 79 Btu ft ft h R conductivit
14. Figure 33 Example geothermal step function Note that the formula for temperature gained from the geothermal step is T 40 depth 100 Assume 55 gallons of diesel fuel in a 3 inch deep pool The density of diesel fuel 61 Ib ft 2 Burn rate 0 12 inches of fuel depth per minute 2 Heat release 19390 Btu Ib from table in Appendix B 2 3 55gal x E 7 35 f diesel fuel 1 7 35 ft x 29 4 ft area of pool 025453 fe SS 3 Heat Release Rate UB AD NS MEN LE OED 11827 9Btu min x ft 12in ft Heat Transfer 11827 9Btu min x ft x 29 4 ft 347 740Btu min Duration of fire EE S 25min used as Time Span of Dynamic Simulation in 0 12in min the control cards Reference Q 70 000 approximate time 0 airflow of branch Lead time 1 minute assumed diesel fuel ignition is nearly immediate and based on spread of fuel from a drum into a pool thought to be reasonable for this scenario Determine CO as a fume 51 Note proprietary names of fuel components removed from this example Only major hydrocarbon is shown A lab analysis of fuel can be used by the modeler Major hydrocarbon Gala CioHs _C14H30 Gala CioHs Gelz Guabla Gala CaHioNe Cz7HioN2 CaHg CsHyz TF5 100673 o 0 3824 0 0663 o 0 2 0 00877 0 00877 0 0 00663 02 Hydrocarbon Oxygen carbon dioxide water vapor oxides of nitrogen Molwt 1 2 C4Ho 125 Oo gt 8 CO 9 H20 57 2 1 CioHs 12 O
15. Pine o 255 Reference Fire Protection Handbook National Fire Protection MJ 947 817 Btu MJ Association 18th Edition 2003 Section 1 Appendix A kg T 2 2046lb kg 75 11 Appendix E Wood Weights and Heat Values Weights and Heat Values of Wood Green wood Dry 12 moisture Green wood Dry 12 moisture hestnut ottonwood White Elm ickory ugar Maple ed Maple White Oak 4 230 Yellow Pine 3 240 White Pine 2 250 lack Walnut 3 420 ed Oak 5 760 3 960 76 12 Appendix F Table of Conversion Factors between Imperial and SI Units Quantity Imperial to SI A Area Acceleration Force Velocity Velocit tms 32808 f s gt NE ui UIT ba ER LUNG dE LE TL ou RN lyd 4 5076456 m ing gat ase tre um E gg Volume Flow 1ft s 0 02832 m s ims 35 315 0 imn s00004 2 mis 21188 mn Him pah 2000435 m i a 15200 eh 1imp gal min 0 00455 mim 1m min 2200 imp gal min Easa emn ies 020 imp gamin 0 07575 litres 1l ires 13 20 imp gal min en 1U S U S gal min 0 06313 litre s Mass gt kg 2220482 b SI to Imperial 232808 nin oe ze E I0 N e 39 370 1 10 7639 3 2808 70 2248 H 3 Ko olo 8 5 gio 88 go gt ud TT SI to Imperial 1N m2 Pa 0 02088 1 0 11n 000145 pg 1 0 004015 mag m
16. been executed the results of a simulation may be viewed using the Branch Results Fan Results Fixed Quantity or Schematic Views The output data can also be sent to a Plotter or Printer MineFire run errors are listed in the mfire tmp file see section 4 5 1 below and may be accessed by opening the file located the same directory your model is saved in Computational errors are automatically listed in the Error List dialog box immediately following execution This dialog box may be accessed from the Tools Menu in any view MineFire adds a Schematic View menu bar and includes a utility in the Data Phase pull down that allows the user to select the time during the dynamic simulation of the data shown This is shown in Figure 12 Data Phase Non steady state m Branch Parameter None m Junction Parameter None v Record Select v 0 Secs First Prev ved Lat Figure 12 MineFire Schematic View Menu Bar When a contaminant is added to the simulation MineFire inserts a symbol into the Non Steady State Data Phase of the schematic to represent the movement of the fume front This is shown in Figure 13 Figure 13 MFire Fume Front Symbol 31 4 4 1 List Errors Upon Executing the MFire kernel MineFire acts similarly to VnetPC and evaluates the model represented by the current files The simulation procedure tracks any errors in the model data which may affect the evaluation Some errors prove fa
17. e Length of Airway 100 000 feet 30 480 meter e Cross Sectional Area 100 000 square feet 9290 meter e Perimeter 10 000 feet 3 038 meter 35 4 4 2 Displaying the Results using the Schematic The on screen schematic is perhaps the most user friendly way to input and view data Ventilation networks can be entirely developed within the Schematic View and it provides a rapid means of viewing the network results In the Schematic View different parameters may be plotted onto the network using the Preferences Menu This view displays resistance data airflow and pressure drop results as well as sources of heat and or contaminants and temperature fronts produced by MineFire The view also displays the data statically at a time interval selected by the user and allows the user to move through the results dynamically at pre selected time intervals The MineFire Schematic View tool bar gives the user the tools to display MineFire parameters on the schematic and to view the various time phases of the data The tool bar is shown below in Figure 17 MineFire and VnetPC Pro support advanced zoom By holding down the SHIFT key while pressing the ZoomIn or ZoomOut Magnifying Glass buttons the zoom will be increased by a factor of 10 Data Phase Initial v Branch Parameter Rock Temp Y Junction Parameter None Y Figure 17 MineFire Schematic View Tool Bar The Data Phase pull down menu item allows the
18. enne enne nen tnn en nens r innen en renes nens 12 3 2 DESGRIPTIVE DATA ins eee eer reet etri epe ee eee reef p EUER CU peret eere ters 13 3 2 1 File Names ise tin auae cea nere Ie d 13 3 22 Units nd Conversion Utility eer te deena eben de de 14 3 2 3 TT EEN 14 3 2 4 Air Density and Regulator Sizing esee nennen rennen 14 3 2 5 Notepad Comments crs ess icto etti deett te eec ea dope e eee ee Rete ah 14 3 35 BRANCH DATA se Eege dasa te Se pokes onn petii 14 3 3 1 Branch Input VieW agunt itp etd me pe te i ette etes 15 3 3 2 Branch Average Values 2c itte td ted cete rtu ete pene ea ped ped 16 3 3 3 Branch Data Formots ioiei snai nsa sns nsns nsns n sanas asas sess asas rs asas ae 17 3 4 JUNCTION BC NEE 18 3 4 1 Temperaturer R 18 3 4 2 Methane E 19 3 5 MINEFIRE CONTROL Data 19 3 5 1 Contro D ia Ee erede Eege 19 3 5 2 GOntTOL EE 21 3 5 3 TEEN 23 3 6 THAN DAT E 24 317 CONTAMINANT DATA 8 oiii rer eee EENS e EA 26 3 7 1 eeh E EE eege RES 27 3 7 2 t 27 3 7 3 He t TV ANS i aee dete ote eic aee ee 27 3 7 4 Qs Concentration d so e EU CREDO OE D EE 28 3 7 5 Contaminant Production 28 3 7 6 He t Production ais eee eee eee e E EI 28 3 7 7 Reference EE 28 3 7 8 Lead Time gd AANEREN EE EE 29 OPERATING THE PROG RAM sais eege deeg eege ege EES 30 41 MANAGE NETWORK FILES nueces ete epe eet oio cer ee bett oe pedet dus 30 4 2 DATA
19. entered for junctions and branches The Edit button 2 on the Editing toolbar is the most straightforward way to access the Junction Data screen and the Branch Data screen where the information may be input MFire Average Values E ft 2 hr pen Deeg Ibm min 2 f Set Defaults ft Thermal Diffusivity of Rock Thermal Conductivity of Rock Friction Factor Length of Airway ft 2 Sectional Area of Airway Perimeter ft Jit Use Average Values in MFire simulation Figure 20 MineFire Average Values Screen 5 4 1 Junction Data Clicking on a junction with the edit tool brings up the Junction Data screen shown in Figure 21 below Junction Data E Junction Number E x Coordinate 243980 ft Cancel Y Coordinate 204190 ft Z Coordinate fo ft Default 2 0 0 Group Number 2 D Group Name vnetpe D Temperature fo Degree E Methane Pet fo I In Atmosphere 41 Figure 21 MineFire Junction Data Screen In the Junction Data Screen the air Temperature and Methane Pct concentration are entered for the junction selected The junction may also be specified In Atmosphere if the junction is in outside ambient air i e a surface intake or exhaust junction portal shaft collar etc These data must be entered for each junction in the model and should reflect as accurately as possible the true conditions in the underground facility relative to the mod
20. mail support mvsengineering com Internet www mvsengineering com 2 Overview of MineFire MineFire is a Windows based package of Programs which combines the utility of the former US Bureau of Mines MFire technology with the relative simplicity of Windows data representation and reliability of the VnetPC Program MineFire is designed to assist the mine ventilation practitioner with the prediction of spread of contaminants heat or other changes in air density Given data that describes the geometry of the mine network airway resistances dimensions characteristic curves of fans and characteristics of the fire or thermal event the Program will Provide tabular representations of various predicted ventilation contaminant and temperature parameters as well as graphical representation of the ventilation system and fume front Propagation over selected time increments This information can then be used to show the effects of the thermal event on the system and modify designs accordingly if engineering judgment deems proper 2 1 MineFire Its Applications and Uses Transient distribution modeling is useful in many ways The assumption of constant airflow rates is justified at the initiation of a fire when it does not influence airflow patterns However at a later stage the intense fire may noticeably impact the ventilation system and with fire intensity controlled by the air supply to the fire the interaction must be taken into account
21. out of the network This tool zooms the extents of the schematic to fit the screen This tool creates inserts a junction This tool creates a new branch This tool feature a drag and drop approach Select the initial point and drag to the second point keeping the left mouse button depressed This tool creates a fan or fixed quantity and inserts it in the selected branch This branch adds a contaminant to the selected branch This feature is disabled in MineFire This tool allows the user to annotate or add text to the schematic This tool allows the user to window or zoom in on a specific area in the schematic The user may zoom to a window by dragging a rectangle on the screen The user may also zoom in and out using the left and right mouse buttons respectively each click will zoom in or out one division This tool allows the user to rapidly erase selected objects This tool allows the user to edit the details of an object This tool allows the user to rotate the schematic The mouse is used to drag the schematic around a central axis to clarify the view of the network Change the view to the cross section Change the view to the long section View all groups layers in the plan view View only the active group layer 70 Isometric Edit Groups All Groups Selected Groups View the schematic in three dimensions The schematic can then be actively dragged around Edit the layer attributes Vie
22. representing the fire relative to clean airflow entering the airway The contaminant gas depends on what the engineer wants to measure CO CO etc or a mixture of gases however the program will only output one fume concentration based on this and the flow rate value Like Flow Rate this variable may be found in various publications or calculated using the combustion chemistry and chemical analysis of the material being consumed by the fire Once the combustion chemistry of the material has been determined the amount of oxygen needed oxidize into the contaminant can be determined Then the mass flowrate and volume flowrates can be found From flowrate concentration can be determined Refer to section 6 0 for example calculations It is only used in oxygen rich cases when modeling fuel rich fires 0 is left as a place holder Units are in percent Defined as CONC although it is rarely shown in the text output 3 7 3 Heat Transfer The amount of heat produced by a fire depends on the fuel s heat of combustion This depends on the amount of energy produced per unit of mass burned the mass of fuel burned and the efficiency of combustion A fire burning at a constant heat release rate will burn fuel mass at a constant rate The Heat Transfer value Btu minute may be calculated by multiplying the heat of combustion Btu pound by the burn rate pounds minute of the fuel for the fire being simulated Sample calculations are provid
23. toward a fuel rich state when located in low flow entries or when throttled Fuel rich fires are relatively rare but when they are encountered the Heat production and Contaminant production Variables are used e How long might the fire burn and how long will it take for the fire to reach full strength from the time of ignition Since MineFire is built around the VnetPC platform it is structured such that the user moves between views or windows where input and output data are located It is understood that the user should have a basic understanding of the operation of VnetPC before undertaking significant operation with MineFire Refer to the VnetPC Pro User s Manual for the necessary information regarding views data input setting up and running a model and general operation of a ventilation network simulation 11 A single file is used to store information the network input schematic coordinates and heat contaminant fire data A separate archive file may be used to store multiple fan curves Creating importing editing and viewing fan curves can be performed within the MineFire program or by importing curves from a pre built fan file fdb MineFire comprises eight screens for the input and display of program data The user will note that the Branch Results and Fan Results are disabled in MineFire however the information is accessible in the Schematic view or in the MFire Results text view MineFire adds menu options on the rig
24. 0 MineFire Contaminants Screen 26 Figure 11 MineFire Add Contaminant Screen esrarvrarvnavenrnenrnenvnennnnnvnnnvnnvnenenrarnrnsvraserasevsssvsssnee 29 Figure 12 MineFire Schematic View Menu Bar 31 Figure 13 MFire Fume Front Symbol AAA 31 Figure 14 Mffrre tmp Text Output edd 32 Figure 15 Shaft portal arrangement resulting in error srronrronvnonvvnnvvnnnnnnnnnenrarnrnsvraserasensssnsesne 33 Figure 16 Shaft portal arrangement corrected ssseeseeeeeeeeenren rennen 33 Figure 17 MineFire Schematic View Tool Bar 36 Table 2 Branch Parameters by Data Phase 37 Figure 18 Reversed entry Symbols essere ener nennen nennen nenne 37 Figure 19 Model Information View 0 ceecescesecescesseeeeeeeseesseeeseecsaecsaecaecaecsaeesseeseeeseeenneeees 40 Figure 20 MineFire Average Values Screen 41 Figure 21 MineFire Junction Data Screen 42 Figure 22 MineFire Junction View sepicis enni eaa a e ii i a 42 Figure 23 MineFire Branch Data Screen 43 Figure 24 Branch Input View MineFire poarameterg eene 43 Figure 25 Example ventilation network esses ener nennen nennen 44 Figure 26 MineFire Average Values dialogue box sese 45 Eigure 27 Mane Fire menu t last sat ehe ete eee tete ke rue n eene rh EE ec 45 Figure 28 Control Data I dialogue box 46 Figure 29 Control Card II dialogue box 47 Figure 30 MineFire Contaminants Screen 48 Figure 31 Ventilation Network Resul
25. 0 0115 26 a pia 200 0 93 00 00 531 180 00 54 00 12312 Junction Parameter 28 2 pia 250 16 50 00 1563 180 00 5400 009163 None v 28 28 pia 250 1500 00 849 5 240 00 6400 0 11111 Enabled wd File GoTo Edit View Branch Tools MineFire Window Help E Dos AN a Data Phase Be c E 2 2700VENT Ii 2 Shock Loss Group Group Factor Number Name Branch Parameter Airflow v 4 Defaut None 186 0085 EN 0 0 1 Disabled 0 00000 O Enabled 2 2700VENT 2 Detaut None 186 0 065 0 0 2 Disabled 0 00000 O Enabled 2 2700VENT gjDetaut R 186 0065 S 0 0 3 Disabled 0 00000 OlEnabled 2 2700VENT Junction Parameter 4 Defaut None 185 0065 67 98 0 0 4 Disabled 0 00000 O Enabled 2 2700VENT None v S Detaut None 186 0065 68 0 0 5 Disabled 0 00000 OlEnabled 2 2700VENT Figure 2 MineFire Branch Data View Unless the modeler has used the k factor airway type for setting up the ventilation network it is likely that the length perimeter and area parameters will not be filled in for a majority of the branches in the model These values must be entered for each branch in the model for the transient time utilities in MineFire to function properly If not the user will receive errors with a list of branches containing missing parameters upon executing the MFire kernel Not all of the MineFire Parameters in Branch Data must be entered for successful simulations In a fire simulation Conductivity Diffusivity and Rock Temperature v
26. 000 0 000 C4Hs 57 8 12 5 0 06633 0 465 0 410 0 261 0 205 C5H1 72 5 8 0 2 0 711 0 611 0 389 0 306 1 00 4 22 3 70 2 36 1 85 Fuel rich Case Flowrate of oxygen 231 cfmO Contaminant Production Oxygen Rich Case Flowrate of CO 3533 cfm CO Concentration of CO 5 0596 0 361 cfm CO cfm Os b Determine the oxygen concentration leaving the fire Oxygen Rich Case Mass flowrate of oxygen into the fire 1102 5 Oxygen consumed 805 Oxygen mass flowrate out of fire 297 5 Flowrate of oxygen 3966 67 Oxygen concentration 5 67 53 lb O min lb O min Ib O gt min cfm O Oz O rich Flowrate CO cfm 396 865 0 000 1135 653 390 965 0 000 583 258 26 036 26 036 0 000 0 000 390 965 583 258 3533 04 Fuel rich Fuel rich Op rich inflow Flowrate inflow rate O CO rate Oo Ib min cfm Ib min 2 506 9 355 106 30 0 000 0 000 0 000 298 97 7 047 26 769 8 2 468 9 216 104 72 0 000 0 000 0 000 3 771 13 748 159 97 0 162 0 614 6 854 0 162 0 614 6 854 0 000 0 000 0 000 0 000 0 000 0 000 2 468 9 216 104 72 3 771 13 748 159 97 22 36 83 28 948 39 1 100 cfm 21 83 28 cfm CO 231 3533 70 000 cfm air 70000 cfm 0 075 0 21 4 22 IbO Ibf 1911 bf min 1102 5 805 297 5 0 075 lb ft 3966 67 70 000 cfm 6 2 Wood Shaft Fire Example A fire scenario has been conceived in a small metal mine which is seen in Figure 34 Air is delivered and removed via two shafts which are wood lined
27. 1 serves as the Reference resistance of 0 000001 can then be drawn from the surface intake and exhaust branches to the Reference Junction An example is shown in the angled branches in Figure 25 below The Junction Range option in the Preferences menu can be used to hide this dummy atmosphere junction if it is set up as junction 1 or junction 9999 for example 43 Remember that surface junctions of surface intake and exhaust branches as well as the reference junction need to be checked In Atmosphere in the Junction Data Dialogue Box 0 0 0 0 gt 3 gt 4 Figure 25 Example ventilation network 5 4 3 Average Values MineFire allows the user to enter average values to replace large numbers or identical or substantially similar branches within the ventilation network The Average Values function allows the user to leave parameters entered in the Branch Input dialogue box as 0 for variables which can be approximated by mine averages This is particularly useful for Conductivity and Diffusivity if only one value is available i e for a bedded deposit The Average Values screen is shown in Figure 26 The check box must be checked for Average Values to be functional It is important to note that the MFire code will return errors in the MFire out and MFire tmp files MFire Results view resulting from the zero values left in inputs The text of the errors will state the program is replacing t
28. 14 Ib CO min Flowrate of CO 8 14 Ib CO min 0 075 Ib ft 108 5 cfm CO Contaminant Production 1100 cfm x 21 O 231 cfm O5 108 5 cfm CO 231 cfm O gt 0 47 POUR O2 4 Determine the oxygen consumed by combustion of Rubber Equivalent C6Ho CeoHs 9 5 O2 gt 12 CO 7 H20 Massssn 0 468 Ib Ib tire C 03 gt CO Massc 0 455 Ib Ib tire S 02 gt SO Masss 0 012 Ib Ib tire SBR 0 468 Ib x 32 g mol O2 158 g mol SBR x 9 5 mol O2 0 9 Ib O2 Ib tire C 0 455 Ib x 32 g mol O2 12 g mol C x 1 mol O2 1 21 Ib Oz Ib tire S 0 012 Ib x 32 g mol O2 32 g mol S x 1 mol O 0 012 Ib O Ib tire Total oxygen consumed 2 12 Ib Oz Ib tire Burn rate of tires 54 Ib tire min Mass flowrate of oxygen into fire 10 000 cfm x 0 075 Ib f x 21 157 5 Ib min Oxygen consumed by combustion 54 Ib tire min x 2 12 Ib O gt Ib tire 114 5 Ib O2 min Mass flowrate of oxygen out 157 5 Ib min 114 5 Ib min 43 Ib O min 66 Flowrate of oxygen out 43 Ib O min 0 075 lb ft 573 cfm O Concentration of oxygen in exhaust 573 cfm O 10 000 cfm air 5 73 5 Perform the same steps for diesel fuel first air fuel ratio Note Proprietary names of fuel components removed from this example Only major hydrocarbon is shown A lab analysis of fuel can be used by the modeler Major hydrocarbon Gala CioHs C14H30 Gala CioHs Gelz Guabla Gala CaHioNe C7HioN gt CaHg Geblu 0 0673 0 0 3824 0 06
29. 2 gt 10 CO 4 H2O 128 3 1 C14H30 21 5 Oo gt 14 CO 15 H2O 198 4 1 Cs5H12 8 O gt 5 CO 6 H2O 72 5 1 CaHioNz2 8 5 Oo gt 4 CO 5 H2O 2 NO 86 6 1 C7H1oNz 115 Oo gt 7 CO 5 H2O 2 NO 122 a Stoichiometric ratios for diesel fuel Molwt Moles Stoich g mol O2 Ratio C4Hs 57 12 5 30 51 30 51 1 57 12 5 32 23 CioHs 128 12 13 04 C14H30 198 21 5 15 11 C4Hg 57 12 5 30 51 CioHs 128 12 13 04 C5H12 72 8 15 46 C14H30 198 21 5 15 11 Caas 198 21 5 15 11 C4H4o0N2 86 8 5 13 75 C7H10N2 122 11 5 13 11 C4Hg 57 12 5 30 51 TF5 Air fuel ratio mass weighted average 18 329 g air g fuel 1 Ib of fuel takes 18 33 Ibs of air to burn Mass flow rate of Oz fuel rich case 17 3 Ib O min 17 3 1100 0 075 21 Mass flow rate of O2 oxygen rich case 735 Ib O min 105 70 000 1 5 0 075 21 52 lb 02 lb CO2 lb CO actual Ib con per lb Produce CO2 Molwt Mol Mass sumed fuel d perlb Produced g mol C Mol02 Fraction perlbfuel theor fuel per Ib fuel C4Hsg 57 8 12 5 0 06733 0 473 0 416 0 265 0 208 Cool 128 10 12 0 0 000 0 000 0 000 0 000 C14H39 198 14 21 5 0 38246 1 329 1 190 0 757 0 595 C4Hsg 57 8 12 5 0 06633 0 465 0 410 0 261 0 205 CioH3 128 10 12 0 0 000 0 000 0 000 0 000 Ces 72 5 8 0 2 0 711 0 611 0 389 0 306 C i4Hao 198 14 21 5 0 00876 0 030 0 027 0 017 0 014 C 4Hao 198 14 21 5 0 00876 0 030 0 027 0 017 0 014 C4H4o0N2 86 4 8 5 0 0 000 0 000 0 000 0 000 Cz H oN2 122 7 11 5 0 0 000 0 000 0
30. 63 0 0 2 0 00877 0 00877 0 0 00663 02 Hydrocarbon Oxygen carbon dioxide water vapor oxides of nitrogen Molwt 1 2 C4Hg 125 Oo gt 8 CO 9 H20 57 2 1 CioHs 12 O gt 10 CO 4 H2O 128 3 1 C14H30 21 5 Oo gt 14 CO 15 H2O 198 4 1 Cs5H12 8 Oo gt 5 CO 6 H2O 72 5 1 CaHioNz2 85 Oo gt 4 CO 5 H20 2 NO 86 6 1 C7HioNe 11 5 Oo gt 7 CO 5 H2O 2 NO 122 b Stoichiometric ratios for diesel fuel Molwt Moles Stoich g mol O2 Ratio GH 57 12 5 30 51 30 51 1 57 12 5 32 23 C Hs 128 12 13 04 C14H39 198 21 5 15 11 C4Hsg 57 12 5 30 51 Carly 128 12 13 04 Cs5H12 72 8 15 46 C14H39 198 21 5 15 11 C14H39 198 21 5 15 11 CaHoN 86 8 5 13 75 Ga 122 11 5 13 11 C4Hs 57 12 5 30 51 CsHip 72 8 15 46 TF5 Air fuel ratio mass weighted average 18 329 g air g fuel b Determine Burn Rates and Heat Transfer Fuel rich Case 1100 cfm 0 075 Ib ft 18 329 g air g fuel Max Burn rate 4 501 Ib fuel min 67 Oxygen Rich Case 10000 cfm 1 5 0 075 Ib ft 18 329 g air g fuel Max Burn rate 27 279 lb fuel min Heat Transfer 50 over ventilated 528 948 Btu min c Determine CO as a fume 1 Ib of fuel takes 18 33 Ibs of air to burn Mass flow rate of O fuel rich case 17 3 Ib Oz min Mass flow rate of O oxygen rich case 105 Ib Os min lb O2 lb CO2 Ib CO actual Ib con per lb Produce CO2 Molwt Mol Mass sumed fuel d perlb Produced g mol C Mol02 Fraction perlb
31. 73 830 Ib Burn time 73 830 Ib 137 5 Ib min 537 minutes per segment However one must consider that growth rate will be slow and determine the volumetric consumption rate 137 5 Ib min 17 58 Ib ft 7 82 ft min surface consumption rate Exposed surface 280 ft x 6 sets 1680 ft Penetration rate 7 82 ft min 1680 ft 0047 ft min 0 0559 in min This assumes that the entire shaft segment and all compartments are involved Assume that the fire begins in one compartment Let the length of the fire at any one time 4 diameters assumed Hydraulic diameter Dj 4A P 4 x 74 7 38 7 7 72 ft A area amp P perimeter from measured shaft compartment dimensions Length 4 x 7 72 31 ft Heat Transfer 31 ftx20 ft perim of I compartment x0 0047 ft minx17 58 Ib ftx8044 Btu Ib 412 000 Btu min 55 2 Determine Contaminant Concentration CO is the contaminant of concern in this case Using the following data from Speight 1993 see 11 for other contaminants and a full description lt 400 C gt 1000 C Yield of gas 125 gt 550 m ton wood 2 21 gt 9 71 ft lb wood CO 30 20 CO 25 25 this unit is shown as a short ton 1 ton 2 000 Ib in the reference determine the amount of gas produced at a given temperature Assume gas production 0 at 120 C Amount of gas emitted by combustion of 1 ton of wood ata given temperature 1200 1000 800 600 400 200
32. CONVERSION PREVIOUS VNETPC VERSIONS rerrrerrernnnrnrnrnrsensnnrnrnrnserenennrnnnenssnenennrnnnrnsenenen 30 43 EXECUTEMINEFIRE KERNEL etre sectio esee tea vete EXE ERA EE EVE Ep E E PEE RR as 4 4 VIEWING THE RESULTS OF A SIMULATION eene ethernet nnn nns s stent nnn nsns esent rena nennen 4 4 1 PASC KEIER Aide dd NEE EENS dee EE 4 4 1 1 Capacity of Surface Arrays Exceeded sss enne 4 4 1 2 Dead end Branches 4 4 1 3 Fan Errors 5er Sn nan 4 4 1 4 Check Unlikely Value for Temperature 4 4 1 5 HTPO2 For Fire Source __ Is Unlikely High Anomalous Consequence May Result 34 4 4 1 6 Branch Omitted in Mesh Selection 4 4 1 7 No Mesh Found for Branch 4 4 1 8 Iteration Tamit Exceeded eet EE 4 4 1 9 Warning Message and Errors Message Temperature rrnrnrrnernornnvrnnrnnernervervnrnenervernernerversevsene 35 4 4 1 10 Too Many Fixed Quantities shton n ia oas are enne nennetnete tenter eea 35 4 4 1 1 Too Many Fans 4 4 1 12 Unit Limits of the Programi siso e ae ie eere ER AROR 35 4 4 2 Displaying the Results using the Schematic esee 36 4 4 2 1 Airflow E 37 4 422 Recirculation 4 4 2 3 Preferences Mens eti ese eidem Eee ere 37 4 4 3 Branch etleche tee ent Nace Repente Rad tanaka pe en E 38 4 4 4 Fan Operating Pointsin nia e ete e ds beaten iu Meader Masa e des ea te eee TAH 38 4 4 5 Fixed Quantity Information deo tt eee inte tte RR te Sessa Pene eve
33. For now use Max emission rate as Flow Rate 334 cfm The fire will eventually engulf the entire shaft Re evaluate this assumption based on simulation results Concentration 334 cfm CO 15 000 cfm 2 2 CO at the fire source 3 Determine O concentration Determine the oxygen consumed by the combustion of the wood Continue with the assumption of 1000 C The following are the reactions for wood that involve the consumption of oxygen C 03 gt CO 9 71 ft lb x 20 O3 1 94 ft CO Ib wood C 14 03 gt CO 9 71 ft lb x 25 O 2 43 ft CO Ib wood H 202 gt H2O 9 71 ft lb x 35 O 3 4 ft H50 Ib wood From above Max burn rate of wood 137 5 Ib min 137 5 Ib wood min x vol gas Ib 267 cfm CO x 0 0833 Ib O2 min 22 2 Ib CO gt min 334 cfm CO x 0 0833 Ib f 27 8 Ib CO min 467 5 cfm H50 x 0 0833 Ib ft 38 9 Ib H O min 57 XC YO gt 22 2CO Y 222 x 32 44 16 1 Ib O2 min XC YO gt 27 8 CO Y 27 8 x 4 x 32 28 15 9 Ib O2 min X H 2Y O2 gt 38 9 H50 Y 38 9 x x 32 18 34 6 Ib O2 min Total O consumed 16 1 15 9 34 6 66 6 Ib O2 min A Volume 66 6 Ib O2 min 0 0833 Ib f 800 cfm O5 Original oxygen content of air 15 000 cfm x 21 3 150 cfm O2 Oxygen content of air exiting the fire area 3 150 cfm 800 cfm 2 350 cfm O5 New airflow exiting the fire area approximate 15 000 cfm total 800 cfm O2 267 cfm CO 334 cfm CO 468 cfm H20 15 269 cfm Ox
34. It is recommended that a VnetPC model used in MineFire be renamed and saved for separate use so that the original model information is not disturbed A file name must be assigned when saving the file for the first time or when utilizing the Save As command under the File Menu When a file is saved the program automatically prompts for the extension vdb Both MineFire and VnetPC support extended file names 13 3 2 2 Units and Conversion Utility MineFire supports both Imperial and SI units The user must initially specify one type of engineering unit however should the user decide to change units then an automatic conversion feature is available This conversion feature is available only from Model Information View by changing the selected unit The conversion utility converts all the input data including the fan curves It is important that the user executes the program following unit conversion In rare cases during conversion one or more data values may become out of range and the program will truncate the values However this will only occur if the original network contains extremely high input parameters and the truncated values should still be sufficiently large so that the network accuracy is not adversely impacted 3 2 3 Power Cost The user may enter an electrical power cost to determine the operating cost for the system fans Power costs are provided in units kW hr where the unit may be any currency although the sy
35. MineFtre Pro A Simulator for Underground Fires USER S MANUAL amp TUTORIAL Mine Ventilation Services Inc 1625 Shaw Ave Suite 103 Clovis CA 93611 USA Telephone 1 559 452 0182 Facsimile 1 559 452 0184 E mail support mvsengineering com Website www mvsengineering com 1 2 Table of Contents INTRODUCTION ee 6 OVERVIEW OF MINEFIRE sa sczssiaccssisssecceocesessacsadasseesastacsseansaxeeeveasanscseaseceastessanceeacsigenasssocsdeaseeccses 7 2 1 MINEFIRE ITS APPLICATIONS AND USES ccccsessscecececeesessscececececseseaeceeccecsesaaeceeececeessaeeeeeeeceeneas 7 2 2 PROGRAM DESCRIPTION AND BACKOGROUND enne eneennnn nsns en ente th nnns sese eterna sss e eene aa 8 2 3 BACKGROUND THEORY OF Mt 8 2 4 LIST OF MAIN PROGRAM FEATURES eernanororvrnrernnnnrnrnenssernennnnnrensnnssennnnrrrnsnsssensnnrnnnsnrsnnnsnnrnnnsnssnnnsnnnnnn 9 2 5 RECOMMENDED SYSTEM REQUIREMENTS FOR MINEFIRE VNETPC cccccecsessscecececeesesssaeeeeeeeneas 9 2 6 SETUP PROCEDURE Liden 10 2 7 SOFTWARE ENCRNPTION E E EA E EE EE S E AAT 10 2 8 DIFFERENCES BETWEEN MINEFIRE AND VNETPC Qerrrnrorroonnnnrrrnvnrsernsnnrnnnenssnenennrnnnensseenennnnnsensensnennner 10 2 9 PROGRAM LDMITATIONS nass sien eite te dade sisse etate asas esset tete ra denen s eren 11 DATA PREPARATION AND INPUT eeeeee ee eese ees stas s esset to s ease te eo e eaa teens eoa eaae e eaae eaa 11 3 VENTILATION NETWORK GSCHEMATIC ene enne
36. Planners may or may not have accounted for this effect when designing escape routes fire warning systems or other components of an underground facility s emergency plan Hence fire generated disturbances to mine ventilation are of concern to engineers Fires in underground facilities produce heat and contaminants which ventilation systems transport through the mine The gases can be poisonous or explosive Heat can change the intended flow of the ventilation system which can transport the gases along unexpected routes or have other unintended consequences Recirculation was an additional problem not addressed until the advent of computer driven simulation packages MineFire is useful to engineers in at least three ways The time series output of the Program is useful for design stage efforts particularly where likely fire sites and fuel sources are known such as maintenance shops and fuel bays For example fire control measures could be evaluated by simulating the effects of a credible fire scenario Second MineFire is useful in cases of forensic investigation in evaluating the likelihood of various scenarios of the spread of a fire or contaminants from a mine fire and in attempting to evaluate past mine fires Third MineFire has uses as a teaching training tool The time required for data entry in model setup somewhat limits this capability however the graphical interface and visual time series output can provide training benefits in
37. Y FROM TO CH4 FUMES TEMPERATURE HEADLOSS gt 0 100 gt 1 0000 gt 100 F lt 0 010 IN WG 13 33 2 0 00 0 0000 33 2 0 000 8 20 21 0 00 0 0000 64 4 0 002 7 19 20 0 00 0 0000 62 8 0 002 30 35 25 0 00 0 0000 61 4 0 002 29 18 19 0 00 0 0000 61 9 0 004 28 19 23 0 00 0 0000 63 9 0 000 27 13 14 0 00 5 0966 1083 4 0 734 25 36 13 0 00 5 0966 1258 4 0 560 24 23 24 0 00 0 0000 65 6 0 000 23 7 36 0 00 5 0966 1358 8 0 185 44 32 1 0 00 0 0000 59 9 0 000 43 1 31 0 00 0 0000 35 1 0 000 IN THE FOLLOWING JUNCTIONS EXIST CRITICAL CONDITIONS JUNCTION CH4 FUMES TEMP F JUNCTION CH4 FUMES TEMP F gt 0 10 gt 1 000 gt 100 gt 0 10 gt 1 000 gt 100 14 0 00 5 0966 1083 4 13 0 00 5 0966 1258 4 36 0 00 5 0966 1358 8 Figure 7 Output detaining critical conditions 3 5 3 Time Table The MineFire menu bar option includes the Time Table item Clicking on the Add button brings up the second screen as shown in Figure 8 This feature allows the user to track events and make changes to the ventilation network at various times during the dynamic portion of the simulation and enter their corresponding start times relative to time 0 This feature is useful in keeping track of multiple actions happening during an event such as e A branch may be changed to an airway of fixed resistance X e A fan may be added the branch changed to a fan branch and the fan curve defined e A branch may be set to a fire branch and the fire parameters de
38. a Phase pull down menu item on the right side of the schematic view A number of parameters may be viewed on the schematic in addition to those normally seen in VnetPC using the Branch Parameter or Junction Parameter pull down menus These include e Rock Temperature e Air Temperature 12 e Methane Production e Methane Concentration e Contaminant data e Rock Thermal Conductivity e Rock Diffusivity 3 2 Descriptive Data Descriptive data consists of both required and optional information for documentation and program initiation The descriptive information is modified in the Model Information View in the VnetPC platform The Model Information View allows data to be directly entered into cells Figure 1 shows the Model Information View following subsections describe the input and required format for the data in the Model Information View with relation to the use of MineFire am VnetPC Pro Lyman Minefire event Example Copy Model Information ve File GoTo Edit View Tools MineFire Window Help D0r d8 cc RS Model Data Title Avg Fan Efficiency 65 We Cost of Power 0 04 S Kwhr Reference Junction 1 Ava Air Density 0 075 Ib fe Une PE Comments pe Data Summary Branches 44 Fans 2 Junctions 35 Fixed Quantities 0 Last Execution of Simulation Date 06 23 03 Iterations 12 Time 12 20 11 Errors 0 Modified Since Yes Figure 1 Model Information View 3 2 1 File Name
39. alues are recommended for each branch in the model Conductivity and Diffusivity will default to 3 00 and 0 10 respectively in the event that cells are left blank The parameters Average Rock Temperature CH Emission Per Unit Area and CH Emission Rate default to 0 Methane concentrations may be used for gas flow simulations as in a coal mine the user would enter Methane Emission rate and Methane per Unit Area in this dialogue The methane parameters also may have a small effect when entered in conjunction with a fire 15 Conductivity This variable is the rock thermal conductivity for the rock mass The number is used by the program to define the thermal diffusion to or from the air as it travels through the airway This will affect airflows in the mine An average value for types of rock may be found in tables of rock property data for instance reference 6 or the value can be determined through lab testing of core samples of each rock type present in the mine An understanding of which rock type defines a branch is needed for detailed models A theoretical average or general value for the rock mass may also suffice Where the rock type in the model is uniform large numbers of branches will have the same value For bedded deposits a weighted average of the rock types being cut is needed The units are Btu hrxftx F or W mx C Diffusivity Rock diffusivity is also obtained through lab testing of core samples or from tables It also h
40. an be ignored and when the source of other errors has been eliminated it will also be removed from the error list Fan is Isolated from This warning may occur in conjunction with a dead end A the Network loop containing a fan or contaminant has been removed from a ventilation circuit and the missing branch or junctions causing the problem must be found and closed Fan Curve Input Must This error may occur when fan curve data has been Be in the Order from improperly entered The fan curve must be entered with Low QF to High QF airflows increasing from lowest to highest in the fan curve Invalid Order Detected table The error may also occur when airflow paths are for Fan improbable based on information in the model when there are dead end branches exist in the model 4 4 1 4 Check Unlikely Value for Temperature This error occurs when the value entered for junction air temperature does not fit with surrounding values and rock temperatures Check for outliers in the data and 0 0 values where data were not entered and re run the simulation 4 4 1 5 HTPO2 For Fire Source Is Unlikely High Anomalous Consequence May Result This error results when the Heat Production variable in one of the MineFire Contaminants is set abnormally high Recalculate or estimate the parameter and run the simulation again Similar errors may be returned for the other variables in the Contaminants View 4 4 1 6 Branch Omitted in Mesh Selection Th
41. andbook National Fire Protection Association 185 Edition 2003 6 Hartman Howard et al Mine Ventilation and Air Conditioning 3 Edition John Wiley and Sons Inc 1997 7 Karmis Michael Mine Health and Safety Management Chapter 24 Mine Fires and Explosions Society for Mining Metallurgy and Exploration Inc 2001 8 Kuo Kenneth K Principles of Combustion John Wiley and Sons Inc 1986 9 Marks Lionel S Mechanical Engineers Handbook 4 Edition McGraw Hill Company 1941 10 McPherson Malcolm J Subsurface Ventilation Engineering Mine Ventilation Services Inc 2009 11 Ballard Tremeer Grant Thesis Emissions of Rural Wood Burning Cooking Devices Appendix D University of Witwatersrand Johnnesburg South Africa 1997 12 Website Long Term Trend in Carbon Dioxide Level www mp docker demon co uk environmental_chemistry topic_2b stoichiometric_ratio html 13 Reisman Joel Air Emissions from Scrap Tire Combustion EPA 600 R97 115 US EPA Office of Research and Development Washington DC 1997 14 Standford Aircraft Hydraulic Fluid Contamination of Jet Fuel Stanford Seto Belcan GE 2002 81 accuracy control cards 22 add fan 25 advanced zoom 36 Applications 7 Atkinson s Equation 18 average values 16 Background 8 branch data formats 17 branch input 12 branch input view 17 24 35 Branch Parameter 12 branch results 12 branch results view 38 chan
42. ans Junctions 0 Fixed Quantities Last Execution of Simulation Date N A Iterations Time N Errors Modified Since Figure 19 Model Information View The model title and any particular description can be entered to further identify the purpose of the simulation The unit basis is selected as either Imperial or SI The average power cost and fan efficiency is also entered This data is used to calculate fan power consumption and the air power cost of each branch in the network reference junction is also selected This junction is associated with the surface conditions relative pressure table will be calculated relative to this point 5 3 2 Schematic View The Schematic View is obtained by selecting Schematic from the Go To Menu The Schematic View is the most convenient means to input data into the model 5 4 Entering Parameters MineFire input parameters are entered for junctions and branches This may be performed using the Junction View and Branch Input View or from the Schematic View using the Edit tool For quick and dirty simulations average values may be entered in the Average Value screen Figure 20 below and any outlying values then entered for other branches Values entered in this screen will take the place of O values in parameters left blank in the Branch Input View It is not recommended for use for length area and perimeter values 40 MineFire temperature methane and rock data is
43. ated at Time 0 in seconds to when it reaches its full and final size is the Lead Time or ramp up time It is assumed that the fire increases in a linear fashion during the ramp up time Defined as TPR and rarely shown in the text output gp VnetPC Pro Lyman Minefire event Example Copy Contaminants mi File GoTo Edit View Tools Contaminants MineFire Window Help Oe weng Heat Production Branch Number From To Description Record 347740 5 0 0 0000 1 Figure 11 MineFire Add Contaminant Screen 29 4 Operating the Program 4 1 Manage Network Files MineFire and VnetPC utilize conventional Windows Protocol for managing files VnetPC files are searched for under the designated vdb file extension and fan files under the fdb extension MineFire also utilizes these files and creates dat out and tmp files in the process of executing Dat out and tmp files are created in the same directory that the working vdb file is saved in Files may be accessed from the host computer or via a network system 4 2 Data Conversion Previous VnetPC Versions MineFire allows import of files from the previous version of VnetPC excluding VnetPC 2000 only models from this or older versions must be cut and pasted or remodeled in a newer version To convert a file the user opens it normally executes the simulation and then saves the file in the new VnetPC Pro format It is important that the file
44. ations seeking convergence of an unsolvable network 4 4 1 9 Warning Message and Errors Message Temperature MineFire allows negative heat flows to simulate cooling stations by giving the appropriate value for the data item HEAT If air temperature drops below 70 F 57 C or rises above 3000 F 1650 C a WARNING message is issued If temperature drops below 200 F 129 C or rises above 5000 F 2760 C an ERROR message is issued and the program will terminate 4 4 1 10 Too Many Fixed Quantities This error message arises if the input data file contains an excessive number of fixed quantity branches If fixed quantity branches are used excessively in interconnecting branches some fixed quantities will be omitted from the mesh selection process Only one fixed quantity branch is allowed per mesh In the case of this error the Branch Input View should be modified to decrease the number of fixed quantity or inject reject branches before the network is re executed Note also that a total number of 70 fixed quantity plus fan branches are allowed in MineFire 4 4 1 11 Too Many Fans The maximum number of fans plus fixed quantity branches allowed is 1000 If the limit is exceeded the user should identify parallel or series fans and simplify those branches and reduce fixed quantity branches where possible 4 4 1 12 Unit Limits of the Program MineFire imposes the following limits on various parameters used within the program
45. atmosphere One In Atmosphere junction must match the Reference Junction specified in the Model Information View and the Starting Junction in Control Card II If it is not specified as such an error message will appear upon execution of the MineFire kernel Junction Data Junction Number E x Coordinate 243380 ft Cancel Y Coordinate 204130 ft Z Coordinate 9 ft Defaut Z 0 0 Group Number 2 v Group Name vnetpc m Temperature 0 Degree F Methane Pet 0 4 I In Atmosphere Figure 4 MineFire Junction Data View 3 4 1 Temperature This parameter is the average temperature of the air in the junction The program assumes complete mixing of the air so for complex junctions the parameter may be determined with a volume weighted average of the temperatures of the intake branches to the junction Airflow measurements and temperature measurements would be needed in 18 each airway flowing into the junction in this case For simple junctions a single temperature reading in the intersection would be sufficient 3 4 2 Methane The Methane parameter is the total concentration of methane contained in the air stream and is also used in branch data section 3 3 to calculate the methane production parameter For complex junctions where intake and return air mix methane concentrations should be measured in each intake and the volume weighted average taken to calculate the value It i
46. bles in this screen follows Contaminant Heat Concentration Heat Transfer Production Production Figure 10 MineFire Contaminants Screen 26 3 7 1 Flow Rate This variable is the flow rate of contaminant gas or gases added to the system by the fire or event which the user wishes to track as fumes in the model The variable may also be used to enter other gases that the user wishes to model such as stench gas The parameter is determined from estimations base on fire handbooks or information derived from fire research institute publications or the National Institute of Standards and Technology NIST It may also be calculated based on the chemical composition of the particular combustible which is being modeled and the airflow Reference Q in the airway being modeled Once the combustion chemistry of the material has been determined the amount of oxygen needed oxidize into the contaminant can be determined Then the mass flowrate can be found From this the volume Flow Rate is calculated Refer to examples in section 6 0 particularly the coal fire example for detailed calculations This variable may be calculated and input for both fuel rich and oxygen rich fires It is necessary for oxygen rich cases Units are in cubic feet per minute cfm Defined as CONT although it is rarely shown in the text output 3 7 2 Concentration This variable is the concentration of the flow of contaminant gases in the branch
47. brium 0 Hours Accuracy in Fume Calculation 0 2 Accuracy in Methane Calculation 0 2 Accuracy in Temperature Calculation 0 Degrees E Pressure Drop Warning Criteria oO in w g Methane Concentration Warming Criteria 0 2 Fume Concentration Warning Criteria 2 High Temperature Waring Criteria 0 Degrees F Boundary Range for Fan Curves Extend by following gradients of two ends Extend left boundary by following gradient and set right boundary gradient to zero Set gradient of both sides of boundary region to zero Figure 6 MineFire Control Card II Screen Starting Junction The Starting Junction is a point in the atmosphere to which portal entrances and shaft collars will be referenced The first parameter is the junction 21 number of the junction that the user wishes to use it must match Reference Junction in the Model Information View The second parameter is the dry bulb temperature of the air at that location The default junction is 1 and temperature is 75 F This is a key parameter to avoiding errors in the model Refer to section 4 5 for the associated error Time Span to Assume Quasi equilibrium This is the time that the program uses to assume a balanced system The program does not account for the consumption of fuel that would put out a fire MineFire will run an event indefinitely if allowed This parameter allows the user to end the simulation and does so by ass
48. c_ratio html 74 10 Appendix D Table of Heat Release Values Heats of Combustion Heat Release Material MJ kg Blasting powder 38 5 Butane C4H0 49 5 Carbon 32 8 Coal anthracite 30 5 34 2 Coal bituminous 23 6 35 2 Diesel fuel 45 0 Dynamite Btu lb 16 552 21 281 14 101 13 908 12 640 19 390 2 322 13 435 12 756 19 819 18 272 18 788 18 616 10 985 11 973 13 285 15 903 20 593 7 670 11 049 18 035 17 068 18 078 10 275 12 403 10 533 TILT 9 815 21 647 15 112 19 690 19 003 19 304 16 015 14 015 6 943 7 201 18 147 9 028 8 684 31 1 31 4 29 67 46 1 42 5 43 7 43 3 24 7 26 4 22 4 33 3 30 1 31 7 36 99 47 9 17 84 21 6 29 8 41 4 42 5 39 7 41 2 42 9 23 9 26 1 31 6 24 0 25 0 17 95 22 83 50 35 34 7 35 6 45 8 44 2 44 9 33 9 40 6 32 6 15 5 16 8 14 0 19 5 42 21 Epoxy Ethanol uel Oil No 1 uel Oil No 6 Gasoline Kerosene Lignin C 5H40 ignite Nylon Nylon 11 Rilsan Octane C3Hjs olyester chlorinated olyester olystyrene olystyrene foam olystyrene foam FR olyurethane olyurethane foam olyurethane foam FR olyvinyl chloride olyvinyl chloride foam Propane C3Hz Rubber buna N Rubber butyl Rubber GRS Rubber isoprene natural Rubber latex foam Rubber Tire auto truck ilicone Rubber ilicone Rubber foam tyrene Wood Douglas fir Wood Oak Wood Spruce 21 8 9 372 Wood White Pine 19 2 8 255 For a range B
49. d or the quantity of air through the branch is fixed an F or a Q will appear 24 in the F Q i column of the Branch Input View In the Fan Input View the user may add a fan by selecting Add Fan under the Edit Menu or by clicking the tool button In the Schematic View a fan or fixed quantity is added using the Fan Tool and dropping the fan on the desired branch A fan can be located in any branch that does not contain a fixed quantity The branch junction numbers dictate the fan location The order in which the junction numbers are entered defines the direction of the fan To view or edit or add to the fans in the model the user may use the Fan Input View Note that unlike VnetPC no fixed pressure fans are allowed in MineFire The user may enter a fan curve by selecting Edit Curve from the Fan Data sheet or Edit Fan Curve under the Edit Menu in the Fan Input View Fan characteristic curves are registered by entering between two and twenty sets of pressure airflow data points Fans with characteristic curves can be entered under fan data or retrieved from the fan data bank or external Fan File Manager Selecting the Edit Curve button in the Fan dialog box will access the fan curve Import will allow the user to select a curve from a Fan File Once the points of the fan curve are entered into the Fan Data Sheet the user can select OK to incorporate the curve into the model Note that the fan curves are unit dependent and that
50. e branches that appear under this heading in the error screen were not included in the mesh formation process and were omitted The truncated network is still evaluated but without the omitted branches Junctions connected to only one branch e g dead end branches usually cause this error If this message appears the network should be scrutinized and amended 4 4 1 7 No Mesh Found for Branch This message arises from the basic branch and mesh selection processes The minimum number of basic branches and meshes required for every network is defined as number of branches number of junctions 1 If for any reason this value is not attained during the basic branch selection process or the mesh selection process this error 34 message will occur The program is designed to continue evaluation of the network based on the number of meshes attained 4 4 1 8 Iteration Limit Exceeded The number of iterations for the Hardy Cross iterative method used to solve the network is limited to 500 iterations If after 500 iterations a balance has not been reached the program terminates and the values obtained after the 500 iteration are listed as the results in the output This error is most often caused by excessive use of very high resistance branches The network data should be checked and the schematic viewed to identify any erroneous branches The iteration limit is set in order that the computer does not spend excessive time performing iter
51. e d 38 4 4 6 Printing Output D t e paie tette ee eade Rob te e de n hee Rea 38 5 TUTORIAL T I 38 Xl INTRODUCTION Jannie ess 38 5 2 STARTING THE Mopp 39 5 3 WORKING IN THE MINEFIRE PROGRAM erorvrrrennnnnnnrrrnssrsnennnnrrrnsnssnensnnrnnnenssnenannrnnnenssennannrnnnensensnenenen 39 5 3 1 Model Information View ie die ei m e rd reti peer iE Eoas 39 5 3 2 Schemane VIEW 52225 feces d seks e eebe eebe 40 5 4 ENTERING PARAMETERS eeenonorornvrrsernannrnrrensrnssennnnrrensssssennnnrsrnsnssnenannrnnnenssnnnannrnnsenssnsnennnnnsenssnsnenener 40 5 4 1 SUNCOM DD GIG eases eset voi eter teri el NEU 41 5 4 2 Br nchi D l as acida eie ideo 42 5 4 3 Average Values 5 dese ieu ede eddie 44 5 5 SETTING CONTROL DATA onra rer tere eee ree eere elei epe rri AE Eed baket 45 5 6 MINEFIRE CONTAMINANTS c 0ccccccecsssssccecececeesssececececsessaaeaecececsensseaececececeesaaececsesenensaaeaeceeeceenss 47 5 7 MODELING STENCH GAS inesse rte eere eee reet eee ere brevet expe ere ENEE proin Ere Eet 48 5 8 EXECUTING THE SIMULATION ccccccssssssccecececsessnaececececeessaseaecececsesssnaececeesceesaaececeescsessaaeaecececeenes 48 5 9 VIEWING RESULTS enano enter ea epe tive etaient 48 6 EXAMPLE HUBS 50 6 11 JDIESEE BXAMPE E Gre itn tati 50 6 2 WOOD SHAFT FIRE EXAMPLE cccccossssssonccscessensccuscseceseensenucesecscesnsnauecsecsceensnncesecesceesenseeseceece sense 54 6 3 COATABIRE EXAMPLE EE 59
52. e for warnings and errors and additional data not found on the Schematic can occasionally be useful especially if the results are unexpected a VnetPC Pro Lyman Minefire event Example Copy Schematic ww File GoTo Edit View Preferences Zoom Tools MineFire Window Help Dec BE Qaj IRERSSAQDZ le ha Le by EPIS CT EI 2 2700VENT v BANE 7 Figure 31 Ventilation Network Results Non Steady State Data Phase 49 6 Example Problems 6 1 Diesel Example A diesel fuel fire is being analyzed in a small shaft mine diagrammed below One intake shaft provides fresh air and air leaves the mine via one exhaust shaft A scenario has been conceived describing a fire involving a 55 gallon drum of diesel fuel that has been temporarily and improperly stored during transit at a sublevel intersection between Level 2 and Level 3 develops a leak and is ignited The fuel spills into a pool 3 inches deep The fire will be simulated in the branch described by junctions 18 19 on the diagram Air density 0 075 Ib ft Figure 32 Small Shaft Mine Example The rock property data is derived from Table 3 ref 6 and Figure 33 determined from sampling below Table 3 Example Rock Property Data Sample Results for Lyman Gneiss Conductivity 1 86 Btu hr ft F Diffusivity 0 065 ft 2 hr 50 Geothermal Step lt Q o a Temperature F
53. e heat value for rubber and vinyl is similar to that of tires so multiply the weight of tires by 10 to account for hoses belts etc Total rubber 1600 Ib x 110 1760 Ib The heat values for hydraulic fluid and oils are less than that of diesel fuel so account for that when converting Relative total volume 53 gal 68 gal 78 Note sum of hyd Fluid and oils 53 gal and fuel volume taken from medium sized wheel loader fact sheet on cat com Relative heating value 13 400 Btu Ib 19390 Btu Ib 69 Total diesel equivalent weight 817 4 Ib x 1 0 78 x 0 69 1 257 Ib 1 Find Air Fuel ratio for Rubber Equivalent tires Major components of tires Styrene Butadiene Rubber SBR CsHy CsHs 46 8 Carbon Black C 45 5 Sulfur S 1 2 Ash other volatiles 6 5 Oxygen consuming reactions C6Ho C6H 5 9 5 O2 gt 12 CO 7 H20 moleweight SBR 158 g mol C 02 2 CO moleweight C 12 g mol S 0 gt SO moleweight S 32 g mol 64 Stoichiometric ratios air to burn each component SBR 1 158 g mol SBR x 9 5 mol O x 32 g mol O 23 O air mass 8 37 C 1 12 g mol C x 1 mol O2 x 32 g mol O2 23 O air mass 11 6 g air g S 1 32 g mol S x I mol O2 x 32 g mol O2 23 Oz air mass 4 35 g air g S weight average of stoichiometric ratios air fuel ratio 8 37x46 8 11 6x45 5 4 35x1 2 9 25 g air g tire 2 Find Heat Transfer and Burn Time for Rubber Equivalent Assume the fire is 50 over vent
54. e shown below CH 7 50 gt 6CO 3H O Cola 80 gt 6CO 4H 0 CgHjp 8 50 gt 6CO 5H O Cla 90 gt 6CO 6H O C6Hy4 9 50 gt 6CO 7H O For the reaction of I gram of hydrocarbon we can calculate the mass of oxygen required for complete combustion as follows Amount of hydrocarbon present in 1 gram n m M 1 M where M is the molar mass of the hydrocarbon If ng is the number of moles of oxygen required for the combustion of one mole of the hydrocarbon obtained from the chemical equation and the molar mass of oxygen is 32 gmol then Mass of oxygen required to combust one gram of hydrocarbon 1 M x no x 32 Air contains about 23 oxygen by mass compared to 21 by volume so Mass of air required to combust one gram of hydrocarbon 1 M x ng x 32 0 23 Hence we can calculate the stoichiometric ratio the relative mass of air needed for complete combustion for any hydrocarbon Representative values are given in the table below moles of O needed 73 for complete combustion compound molar mass gmol Stoichiometric ratio ng s cyclohexadiene I r hexane cyclohexane For a typical petrol with a blend of many hydrocarbons the stoichiometric ratio is about 14 7 1 to three significant figures or about 15 1 to two significant figures From Long Term Trend in Carbon Dioxide Level mp docker demo co uk environmental_chemistry topic_2b stoichiometri
55. ed in Section 6 0 and Appendix B A table of 27 values of Heats of Combustion for various materials which may be found in a mine is found in Appendix C For fires containing a mix of materials such as an equipment fire the engineer must determine the combustible materials present the quantities and develop or determine an approximate burn rate Then he may calculate the average heat transfer value for the total fuel mass based on each of the fuels available The variable is defined as heat in Btu added to the airway per unit time minutes Defined as HEAT when shown in the text output 3 7 4 03 Concentration This variable is defined as the oxygen concentration of the air current leaving the location of the fire or event It is calculated by determining the chemical reactions that consume oxygen and then the amount consumed may be determined based on the ratio of each reactant present in the fuel The user then can find the total amount of oxygen consumed by the fire and solve based on burn rate the original intake airflow and intake oxygen quantity Complete examples are given in section 6 0 Units are in percent This variable is defined as O2MIN although it is rarely shown in the text output 3 7 5 Contaminant Production The contaminant production variable is defined as the amount of fumes or contaminant gases produced by the fire per unit volume of oxygen delivered to the fire Once the combustion chemistry of the material has b
56. ed in the VnetPC Pro User s Manual Note that an average value must be entered for the temperature parameter in Junction View to run a simulation Default values in the Control Cards are generally acceptable for the base model The initial model should be saved as one file before executing the MFire kernel Errors will likely occur during execution of the kernel and resolution of these using a separate file is helpful Once resolved using a renamed file a correlation exercise should be carried out and when the model correlates this file should be saved as a base model Models can be created from this for use in fire event simulations For the purposes of this tutorial it is assumed that the user is beginning the process with a complete assembled and correlated ventilation model 5 3 Working in the MineFire Program 5 3 1 Model Information View The Model Information View is the first view presented to the user when an existing model is opened The general data required most likely was already entered when building the base model If it was not it may be entered at this point 39 mi Untitled Model Information Model Data Title Tutorial 1 Example Mine Avg Fan Efficiency E x Cost of Power Dn k W hr Reference Junction zz Avg Air Density 0 075 Sir Units Imperial Comments field contains comments about your specific mine and or ventilation model Edit Data Summary Branches 0 F
57. een determined the amount of oxygen needed oxidize into the contaminant can be determined Then the mass flowrate and volume flowrates can be found Then the contaminant production value can be found using branch airflow and intake oxygen concentration Refer to section 6 0 for examples A value of 0 is left as a place holder for oxygen rich fires The variable is defined as SMPO2 in the text output 3 7 6 Heat Production This term is actually a constant that is used in the case of a fuel rich fire A value of 0 is left as a place holder for oxygen rich fires The constant is derived from the following combustion relationship C 03 gt CO 300 Btu ft O2 The heat of formation found in the above relationship is equivalent to the heat production value and can be measured in controlled environments according to former Bureau of Mines personnel The value is defined as the amount of heat Btu produced per volume of oxygen delivered to the fire Defined as HTPO2 in the text output 3 7 7 Reference Q The reference airflow quantity defining the fire characteristics or the airflow delivered to the fire in cfm The value is the airflow in the branch airway containing the event at 28 Time 0 Initial phase or with no event entered into the simulation Defined as QCENT and rarely shown in the text output 3 7 8 Lead Time The time during the dynamic portion of the simulation from when the fire or event the contaminant is initi
58. eled airways Care must be taken when complex junctions and airflows are involved to properly average values for air intaking the junction since the MineFire calculation routine assumes complete mixing of air at intersections The data may also be entered in the Junction View spreadsheet although this can become a tedious process if used exclusively Junction S X e Group Group Branches In No EE EE Number Name Attached Temperature Methane Atmosphere ft ft ft all 2419230 1993800 0 0 1 Main Level o e 244060 0 204130 0 002 vnetpc 3 0 00 0 00 r 243980 0 204190 0 002 vnetpc 2 0 00 0 00 r 243870 0 203690 0 002 vnetpc 3 0 00 0 00 r 243810 0 203770 0 002 vnetpc 4 0 00 0 00 r 243730 0 203820 0 002 vnetpc 3 0 00 0 00 r 243590 0 203240 0 002 vnetpc 3 0 00 0 00 P Figure 22 MineFire Junction View 5 4 2 Branch Data The Edit button 2 is also used to open the Branch Data screen by clicking on a branch in the Schematic View Five parameters that MineFire uses are entered in the Branch Data Screen Figure 23 or alternatively in the Branch Input View spreadsheet Figure 24 These include the rock thermal Conductivity rock Diffusivity Rock Temperature Methane Emission rate and Methane per Unit Area The rock property parameters are determined through measurements or lab tests taken at various locations in the mine Explanations of these parameters and procedures for taking the measureme
59. elps define how quickly heat moves between the rock mass and the air as air moves through a branch The units are ft hr or m sec Rock Temperature This variable uses the average temperature of the rock for a given branch Samples can be taken in numerous key locations throughout the mine or the geothermal step can be used to determine average rock temperature at a given elevation and this data averaged as necessary for branches with vertical relief Note that the geothermal step may not give entirely accurate results for older workings where the rock has aged and the temperature profile has changed Methane Emission Rate The methane emission rate is the rate that a mining face or a particular segment of airway emits additional methane into the air stream It is used in conjunction with the Methane per Unit Area and Methane Pct parameters to determine methane concentrations throughout a mine These parameters have no effect on fire calculations This parameter may be determined by taking methane concentrations at each end and airflow measurements near each end of the airway or branch in question multiplying each concentration value by the corresponding airflow value then subtracting the upstream methane flow rate from the downstream methane flow rate Units are ft min or m sec Methane per Unit Area This variable is the amount of methane emitted per unit of surface area of the airway or airways represented by the branch per uni
60. entilation parameters such as the introduction of fire to the system varying outside temperatures changing ventilation control structures or development of new mine workings This is accomplished by using data from ventilation surveys together with information determined from known airway dimensions and characteristics Input data relating to fires is more complex Heat release rates are calculated based on which type s of fuel is are burning The location of the fire in a main intake exhaust airway or area of low flow is important in determining whether to assume an oxygen rich or fuel rich fire which helps the user determine which parameters to use in the fire simulation and which may be left blank Contaminants may be determined based on the chemistry of the fuel components Fire is difficult to predict and the results of a simulation will only be as good as the inputs MVS has attempted to provide the user with explanations reference material and sources and Procedures for determining some of the input parameters It is up to the user to envision credible scenarios according to the specifics of the location or design in question It should also be noted that MineFire allows the user to input parameters in either Imperial or SI units For simplicity sake all example calculations and inputs shown in the MineFire User s Manual are only displayed in Imperial units To switch between Imperial and SI systems the user may either utilize the Pro
61. equation C O gt CO 300 Btu ft O2 3 Determine Contaminant variables CO is the contaminant of concern Assuming we have a 1 Ib sample of coal it takes 9 9 Ibs of air to burn from air fuel ratio so 9 9 lb air Ib fuel x 23 O 2 3 Ib of O to burn 1 Ib of fuel From the analysis of the coal it has 0 669 Ib C 0 131 Ib O2 2 3 Ib O needed to burn coal 0 131 O from coal 2 17 lb O needed from air We know C 02 gt CO C 2 0 gt CO At lower temperatures 400 C production of CO dominates from 11 Analyze the CO equation 0 669 C XO gt Y CO 0 669 x 32 12 2 X 2 1 78 lb 32 12 ratio of molwts 0 669 x 44 12 Y 2 2 45 Ib 0 669 C 1 78 O2 gt 2 45 CO At high temperatures 21000 C a halo of CO2 cover the fuel and C reacts with CO to form CO 11 C CO 22CO 0 669 C 2 45 CO gt 2X CO 0 669 x 28 12 2 X 2 1 56 Ib 0 669 C 2 45 CO gt 3 12 CO This gives us ratios that allow us to calculate mass increases Using a fuel rich case where from the example network the airway in question has an airflow Ref Q of 1 100 cfm Determine the mass flow rate of oxygen 1100 cfm x 0 075 1b ft3 air density x 2196 O 17 3 Ib min O gt Determine oxygen needed to burn Carbon component 17 3 Ib min O5x0 669 IbC Ib coalx11 6 Ib air IbC 10 0 Ib air Ib coal 13 4 Ib min O5 Find the mass flowrate of CO assumes CO CO efficiency 100 13 4 Ib min O gt x 3 12 CO 1 78 O5
62. ers the user must determine whether the simulated fire is oxygen rich or fuel rich Engineers from the former US Bureau of Mines have indicated that fuel rich fires are relatively rare i e gt 1 of cases For an oxygen rich fire the variables Contaminant Production and Heat Production are left blank 0 is input as a place holder MineFire does not allow completely blank cells and other variables are determined For cases when a fuel rich state could be achieved such as a fire in an area sealed by stoppings or bulkheads or otherwise removed from active ventilation the variables Contaminant Production and Heat Production are used and the first four may be left blank Flow Rate may be input if calculated Each variable is discussed in further detail below Multiple events may be added in the simulation either in the contaminants screen all at time 0 or using the time table discussed in section 3 5 in order to simulate multiple fires or to simulate a fire spreading to an intersection or similar scenario Care must be taken to add branches where necessary so that the model is showing the event in the proper location Figure 10 below is the MineFire Contaminants View or the spreadsheet view of the input values Figure 11 shows the Add Contaminants Screen which is reached via the Add Contaminants option found under the Contaminants menu item or by the Contaminants option under the MineFire menu item An explanation of the input varia
63. eviate this problem MineFire automatically creates a new branch 0 1 feet 0 03 m in length for the fire location This helps to prevent divergence due to an air reversal in the fire event branch 14 Unlike VnetPC MineFire limits models to 3 500 branches and 70 fans fixed quantities Reprogramming efforts increased this from the original relatively restrictive limits of 500 branches and 10 fans that were placed on the US Bureau of Mines MFire program This still is reduced from the limits that VnetPC places on branches and fixed quantities however it is not expected that they will cause a problem for typical modeling efforts 3 3 1 Branch Input View MineFire adds a number of parameters to the Branch Input View and Branch Data Screen The modified Branch Data Input Screen can be seen below in Figure 2 For further detail on initial branch entry and creation refer to section 3 3 of the VnetPC Pro User s Manual Ap VnetPC Pro Lyman Minefire event Example Copy Branch Input w Fie GoTo Edt View Branch Tools MineFire Window Help 8 E B dim TTL EEPVGE Does Do Data Phase Qe e E 2 2700VENT v WW V Friction e Pressure Resistance Equiv f Calculated Factor E Row From To Fai Type hen WU Ge lof wenn Pet Length Sg Z i n mesance GEESS e min wa d RA000f ft PU x 10 10 Airflow v 24 25 pio 10 0 43 00 00 174 180 00 5400 0005 25 26 pla 1000 93 00 00 3751 180 00 54 0
64. f the airway Data may be entered in any of the four formats shown in Table 1 The mouse can be used to copy and paste ranges of data between branches in the Branch Input View or from other Windows applications such as spreadsheets or other ventilation simulators Once data is entered into the program the data will be present until deleted or changed The resistance type may be changed so that different parameters can be used to define the resistance but the original data will be saved although it will not be active 17 Data Type Entry Form Comments length measured resistance 1 R airway resistance Fixed resistance 2 p Q frictional pressure drop and quantity Pressure drop volume data B k L Leg A Per friction factor length Required input for Atkinson s equivalent length area and perimeter Equation H R Length L Leq resistance per unit Allows direct calculation of length airway length and equivalent resistance from previously Table 1 Branch Data Types 3 4 Junction Data The Junction View is used to specify junction temperature and elevation in preparation for the natural ventilation calculation as well as methane concentration in the case of a gassy mine MineFire adds three items to the VnetPC Junction View and Junction Data Screen These include the air dry bulb temperature the Methane Pct and a check box to specify whether the junction is in the outside
65. fined This is useful in modeling a spreading fire however care must be taken in modeling the branches properly when attempting this e A branch may be changed to an ordinary airway with the characteristics defined by the branch input view Note that this function cannot be used to terminate a fire The program assumes that a fuel source burns indefinitely after ignition and ramp up e The time increments for viewing the dynamic simulation and calculating the output may also be modified 23 MineFire Time Table Time Action Description Add Edit Delete Time table for condition changes M Condition change Change branch to an ordinary airway and set airflow resistance Change branch to a fan branch and set fan characteristics Change branch to a fire source branch and set contamination parameters Change branch to an ordinary airway Change Time Increment in dynamic simulation Change Output Interval 2 w v Force detailed records ta be set up for airways which are on the immediate down stream side of junctior At Time U minutes after time zero Branch 1 Resistance 0 Figure 8 MineFire Time Table 3 6 Fan Data The user may add fans in the Branch Input Fan Input or the Schematic Views In the Branch Input View a fan is added by referencing the Edit Menu using a button tool or double clicking the cell under the F Q i fan fixed quantity inject reject column When a fan is adde
66. fuel theor fuel per Ib fuel C4Hs 57 8 12 5 0 06733 0 473 0 416 0 265 0 208 C 1oHg 128 10 12 0 0 000 0 000 0 000 0 000 C 14Hao 198 14 21 5 0 38246 1 329 1 190 0 757 0 595 C4Hs 57 8 12 5 0 06633 0 465 0 410 0 261 0 205 CigHg 128 10 12 0 0 000 0 000 0 000 0 000 C5H2 72 5 8 0 2 0 711 0 611 0 389 0 306 C14H30 198 14 21 5 0 00876 0 030 0 027 0 017 0 014 C14H30 198 14 21 5 0 00876 0 030 0 027 0 017 0 014 CaH1oN gt 86 4 8 5 0 0 000 0 000 0 000 0 000 C7H1oN gt 122 7 11 5 0 0 000 0 000 0 000 0 000 C4Hs 57 8 12 5 0 06633 0 465 0 410 0 261 0 205 Ce 72 5 8 0 2 0 711 0 611 0 389 0 306 1 00 4 22 3 70 2 36 1 85 Fuel rich Case Flowrate of oxygen 231 cfmO Contaminant Production 0 361 cfm CO cfm O Oxygen Rich Case Flowrate of CO 504 72 cfm CO Concentration of CO 5 0596 d Determine the oxygen concentration leaving the fire Oxygen Rich Case Mass flowrate of oxygen into the fire 157 5 b Oz min Oxygen consumed 115 Ib Oz min 42 5 b Oo min 566 67 cfm Oz Oxygen mass flowrate out of fire Flowrate of oxygen 68 17 3 1100 0 075 21 105 10000 1 5 0 075 21 Fuel rich Fuel rich inflow Flowrate rate O2 CO Ib min cfm 2 506 9 355 0 000 0 000 7 047 26 769 2 468 9 216 0 000 0 000 3 771 13 748 0 162 0 614 0 162 0 614 0 000 0 000 0 000 0 000 2 468 9 216 3 771 13 748 22 36 83 28 1 100 cfm 21 83 28 cfm CO 231 Oz rich inflow rate O2 Ib min 15 186 0 000 42 711 14 960 0 000 22
67. ges in density 10 concentration 27 Conductivity 16 Contaminant Production 28 Contaminants 26 Control Card 19 Control Card II 21 Control Data I 19 conversion 14 convert 30 create a new VnetPC file 38 Data Phase 12 data preparation and input 11 data type 18 descriptive information 13 Differences 10 Diffusivity 16 Index Displaying the Results 36 errors 32 fan curve 25 Fan Errors 34 fan input and fan results 12 fan results view 38 Features 9 Files 30 fixed quantities 12 Fixed quantity 38 flow rate 27 getting started 38 goto menu 12 Heat Production 28 Heat Transfer 27 import 30 Initial phase 36 input 12 junction data 12 Junction Parameter 12 Kirchhoff s Laws 8 Lead Time 29 Limitations 11 Methane Emission Rate 16 Methane Pct 19 Methane per Unit Area 16 MFire Results 32 mfire tmp 32 model information 12 model information view 13 Non Steady State phase 36 82 Overview 7 oxygen concentration 28 power cost 14 preferences menu 37 print active view 38 Program Description 8 Program Features 9 See Features See Quasi Equilibrium phase 36 Recirculation 37 Reference Q 28 Requirements 9 resistance 17 results 31 Rock Temperature 16 schematic 12 schematic view 17 36 setup Procedure 10 software encryption 10 Starting Junction 21 system requirements 9 temperature 18 Theo
68. gram s conversion feature will be explained in further detail later in the document or reference the table of conversion factors in Appendix F MineFire has been developed specifically for computers operating under the Microsoft Windows environment XP SP2 Vista or Windows 7 The system is supplied on one CD ROM Data files and fan databases prepared using VnetPC for Windows can be used for development of the models Prior to installing the software it is recommended that the user become familiar with this Users Manual This manual Provides an overview of the MineFire package that is recommended for new users as well as for users of various releases of VnetPC Comprehensive Help Menus are included with the Program to further assist users in understanding how the Program works To access the Help Menu click on the Help Menu above the tool bar If you have any questions or comments regarding MineFire please do not hesitate to contact us Mine Ventilation Services Inc MVS maintains a comprehensive web site which includes up to date information on MineFire We also offer free technical support to all users of the latest versions of the MineFire and VnetPC Programs Thank you for choosing MVS software programs and for supporting the continued development of the programs Mine Ventilation Services Inc 1625 Shaw Ave Suite 103 Clovis California 93611 United States of America Telephone 1 559 452 0182 Facsimile 1 559 452 0184 E
69. he zero values with the defaults This is not the case MFire is actually performing the calculations with the average values entered A later version of the program will hopefully be able to correct this problem 44 MFire Average Values teh pum umen Cancel Friction Factor 100 Ibm min 2 f Set Defaults Lenath of Airway 500 ft Thermal Diffusivity of Rock Thermal Conductivity of Rock d e e Sectional Area of Airway 100 m Perimeter ft i Use Average Values in MFire simulation Figure 26 MineFire Average Values dialogue box 5 5 Setting Control Data The control data is accessed from the Control Cards option in the MineFire menu item Refer to Figure 27 below The data are determined and selected by the user then entered in two screens Default values may be entered by selecting the buttons on each of the screens The parameters are discussed in Section 3 5 and the control card input screens are shown in Figure 28 and Figure 29 below me Window Help Execute MFire kernel Control Cards Average Values Time Table Comments Contaminants Figure 27 MineFire menu Values must be entered for all parameters in both control card screens or errors will result The default values are a good starting place when determining the variables On the Control Data I screen the Reference Density and Temperature parameters are the most important in terms of calculation accuracy
70. ht side of the screen an execution tool and input options in a new menu bar item and adds input items to the branch input view and junction view The screens are listed on the Menu Bar under the Go To Menu These views are e Model Information e Fan Input e Branch Input e Fan Results e Branch Results e Junction Data e Fixed Quantities e Schematic e Branch Template e Contaminants This section details the content and form of the input data required for the MineFire program Items relating to the normal function of the ventilation system without the influence of fire heat etc may be set up in a VnetPC model prior to initializing MineFire The data requirements are presented in seven categories 1 Ventilation Network page 12 2 Descriptive Data page 13 3 Branch Data page 14 4 Junction Data page 18 5 MineFire Control Cards page 19 6 Fan Data page 24 7 Contaminants page Error Bookmark not defined 3 1 Ventilation Network Schematic A ventilation network is a graphical representation of a ventilation system and can be built initially in VnetPC or imported from AutoCAD Refer to the VnetPC Pro User s Manual Section 3 1 for further discussion of the ventilation network MineFire adds a time related output function so that the user may view the progression of a fume front and the changes to the ventilation system over time as the fire or other heat input does work on the system This tool is accessed using the Dat
71. ilated Burn rate 10 000 cfm 150 x 0 075 Ib ft3 9 25 Ib air Ib tire 54 Ib tire min Heat Transfer 54 Ib tire min x 14 015 Btu Ib 757 510 Btu min Burn Time 1760 Ib 54 b min 33 min 3 Find Contaminant variables for Rubber Equivalent CO as the contaminant 1 Ib of tires takes 9 25 Ib of air to burn SBR takes 8 37 Ib air Ib SBR x 0 468 3 92 Ib air 3 92 Ib x 23 O 0 90 Ib O2 Carbon Black C O2 gt CO assume very little CO is produced SBR C6H 9 CoHs 9 5 O2 gt 12 CO 7 H20 0 468 C6Ho CeHs 9 5 X O 212YCO 7Z HO X 0 468 x 9 5x 32 158 0 9 Ib O Y 20 468 x 12x 28 158 1 0 lb CO 0 468 CSH9 C6H5 0 9 O2 gt 1 0 CO 7 Z H20 So CO yield 1 0 Ib CO lb tires assuming ideal combustion CO mass flowrate burn rate x CO yield 54 Ib tire min x 1 Ib CO Ib tires 54 Ib CO min Flowrate CO 54 Ib CO min 0 075 lb ft 720 cfm Concentration 720 cfm CO 10 000 cfm air 7 2 65 Fuel rich case use Ref Q 1 100 cfm Mass flowrate of oxygen 1 100 cfm x 0 075 Ib f x 0 21 17 3 Ib O gt min Oxygen needed to burn SBR 17 3 Ib O2 min x 0 468 g SBR g tire x 8 37 g air gSBR 9 25 g air g tire 7 33 Ib O gt min Mass flowrate of CO SBR CsHy CsHs 9 5 O2 gt 12 CO 7 H20 0 468 C6Ho CoHs 9 5 KO gt 12YCO 7Z H50 0 468 x 9 5x 32 158 X 0 9 Ib O2 0 468 x 12x 28 158 Y 1 0 Ib CO 0 468 C6Ho CoHs 0 9 O2 gt 1 0 CO 7 Z H20 7 33 Ib O2 min x 1 Ib CO 0 9 Ib O2 8
72. irflow Reversal Airflow reversal in an airway or airways may occur upon introduction of a heat source to the network For example an event could cause upcasting of a shaft or ramp that is normally downcast The fume and contaminant flow path is tagged with a hatch mark and the reversed airflow arrow see Figure 18 below Particular attention should be paid to these entries Remember that the program assumes a fire or heat source is at the entrance of a network branch a cal TM Figure 18 Reversed entry symbols 4 4 2 2 Recirculation Recirculation of contaminants and airflow may occur in a sequence of airways upon introduction of a heat source to the network In cases when this happens the airway is flagged with a hatch mark refer to Figure 18 above and notations of the path are made in the text output file The user should be particularly aware of these areas especially with respect to the design basis of the facility 4 4 2 3 Preferences Menu The Preferences Menu allows the user to select which output parameters are to be shown and how to show them These parameters include Airflow Pressure Drop Air Power Loss Operating Cost contaminant information Resistance or the Branch Numbers Refer to the corresponding section in the VnetPC Pro User s Manual for a more complete description 37 4 4 3 Branch Results The Branch Results View lists the output in a spreadsheet format Data includes the branch number
73. le for download via our website www mvsengineering com Whether you download or install from a CD simply double click on MineFire exe and follow the directions for installation Please note that your operating system may require you to change permissions for file access while using the software The latest edition of MineFire is programmed with Microsoft Visual Studio and your operating system should be updated regularly through with the appropriate updates provided by Microsoft If you are experiencing problems with during installation please check to insure that your operating system is up to date before contacting MVS 2 7 Software Encryption Depending on which operating system you have the HASP drivers may be automatically installed when the HASP Key is connected to the computer If you connect the HASP key and Windows does not automatically install the associated drivers they are located on the CD thumb drive provided with the software Alternatively they can be downloaded from our website www mvsengineering com The network version of MineFire requires one PC on the LAN network typically a network server to host a HASP key for 5 to 100 users special pricing is available for anywhere between 6 and 100 users This dedicated host for the network software must be running the HASP License Manager as a service or application and host the Network HASP Key Due to the complicated nature of virtual networks and subnets as well as fact tha
74. mbol with remain the This variable is not actually used in MineFire it is aremnant of VnetPC calculations 3 2 4 Air Density and Regulator Sizing Average air density as entered here is not used by the MineFire calculation programs it is used by VnetPC s calculation program to determine an output that can be helpful to some engineers but this is a useful parameter to know and enter here MineFire uses the surface density as entered in the Control Cards Section 3 5 and calculates air density by branch based on airflow temperature and pressure parameters in order to determine the ventilating energies influencing the system 3 2 5 Notepad Comments There is a large text field available to enter a detailed description of the particular file Information may include a title summary of results and the specific details associated with that model This Notepad is seen in the Model Information View Text may be entered directly in the reduced window or the Notepad may be maximized by pressing the Edit key A Comments section is also included in the MineFire menu for other related notes and text 3 3 Branch Data MineFire assumes that a fire or heat sources is at the entrance of a network branch The entrance is the end with incoming air In the event that an air reversal occurs the branch entrance and exit swap ends This may prevent convergence to a solution or simply require additional iterations to achieve a solution To help all
75. mol O2 23 O2 by mass in air 4 35 g air H 1 2 g mol H x 1 2 mol O x 32 g mol O 23 O2 by mass in air 34 8 g air C 1 12 g mol C x 1 mol O2 x 32 g mol O2 23 O2 by mass in air 11 6 g air Mass weighted average 3 5968 x4 35 g gS 5 696H x34 8 g gH 66 9 C x11 6 g gC 0 03 0 ash 9 9 g air g coal Note that O2 in coal will oxidize either with components in air or coal and does not contribute and ash does not combust 2 Determine Heat Transfer values Burn rate 1100 cfm x 0 075 Ib ft 9 9 Ib air Ib coal 8 33 Ib coal min Heat transfer 8 33 Ib min x 12 080 Btu Ib 100 700 Btu min This value is valid in the cross cut consider however that the fire may spread to the intersection due to the low flow Note that branches with resistances of approximately 0 should be inserted between the intersection junction and the existing branches to represent the spreading fire Intake Airflow 58 300 cfm CM section airflow 65 700 cfm Assume that the airways are 50 over ventilated Burn rate intake 58300 cfm 150 x 0 075 Ib ft3 9 9 Ib air Ib coal 294 Ib coal min Burn rate CM 65700 cfm 150 x0 075 Ib ft3 9 9 Ib air Ib coal 332 Ib coal min Heat transfer intake 292 Ib coal min x 12080 Btu Ib 3 560 000 Btu min 60 Heat transfer CM section 332 Ib coal min x 12080 Btu Ib 4 008 000 Btu min In the fuel rich case From Section 3 Heat Production 300 Btu ft 05 from the
76. nts or performing the tests are given in Section 3 42 Branch Data ID 42 From 10 To E Description Type p Q v Resistance P U mme Shock Resistance 0 P U Pressure Dron 3369 min wa Branch Code Default v id asa emi Surface State Exhaust ze Friction Factor u TI lbf ESSET None 3 Resistance per Length R 1000ft EEUU Enabled 3 Length ft eee n Shock Resistance v Area 113 ie MineFire Parameters Perimeter ft Conductivity 1 86 BTU Mr fef Parallel Factor 1 Diffusivity 0 065 f amp hr Group Number 5 v Rock Temperature 51 E CF Group Name 3120VENT CH4 Emission rate D ft min CHA Unit Area 0 ft min Figure 23 MineFire Branch Data Screen Neutral None Return None Intake None Intake None Intake None Symbol Intake None Return None Description Slope South Shaft South Shaft I s cir 1st M Conducivty muas Ros 0 00 0 000 o 0 00 0 000 o 0 00 0 000 o 0 00 0 000 o 0 00 0 000 0 0 00 0 000 o 0 00 0 000 o oo OO OO OH CH4 Emission CH4 Emission Temperature Per Unit Area oo coc OO OH Figure 24 Branch Input View MineFire parameters In developing the model it is important to remember that in MineFire every loop must be closed including the surface intake and exhaust junction or atmosphere junction and is set as such in Control Card II Branches with Junction
77. ribes how to establish a fire simulation model in MineFire using previously established ventilation model that was built in VnetPC It is assumed that the user has read the VnetPC Pro User s Manual is familiar with the tools and functions of the VnetPC program and is sufficiently comfortable working with the views and tools in VnetPC to perform the basic functions The user may refer to the VnetPC Pro User s Manual or Help Tools for additional information Additional help about MineFire features can be found in the Contents section of the Help Menu in the MineFire program The following sections detail how to establish a fire simulation in MineFire and create a new MineFire file from the data The step by step process provides the user with an in depth look at how build and operate a MineFire simulation 38 5 2 Starting the Model The user may start with the most recent ventilation survey model or a future model as appropriate This base model should be saved as a new file with a name relevant to the fire or event simulation project using the Save As option under the File Menu The file may then be opened in MineFire and edited modified and simulations run without disturbing the data in the original base model Alternatively a new ventilation system base model may be built within the MineFire program A dxf file may be imported and branch and fan data entered following the steps outlined in the Tutorial section 5 0 includ
78. ry of MineFire 8 Time Table 23 transient time utilities 15 tutorial 38 units 14 US Bureau of Mines MFire 6 Uses 7 ventilation network 12 views 11 warning criteria 22
79. s and handles errors MfireQ exe initializes two files needed by the other two executables Mfirel exe handles network and temperature portions of the analysis and is also executed at the end of the time dependent portion to develop the steady state results The third program Mfire2 exe handles non steady state or transient portions of the problem The output data are collected in a single output file 2 3 Background Theory of MFire The MFire program was developed with the assumption of compressible flow the inclusion of heat and density changes in calculations and is based on Kirchhoff s Laws Adaptations are included to handle airflow reversals caused by the addition of a heat source The code utilizes a form of the Hardy Cross iterative technique to converge to a solution 2 4 List of Main Program Features Features Dynamic graphical display of symbolic and numerical results Symbols for the event fire and fume front Control of calculation precision time increments use of the fan curve Change the properties of a branch between ordinary airway fire branch and fan branch while an event is in progress Text results available to review Average value function Full color interactive 3D network schematic Advanced zoom function Enhanced expandable coordinate system Data input and output via the Schematic or tabular views Import DXF files from CAD and mine planning programs Ability to enter series and parallel arrangemen
80. s important to note that MineFire needs at least the junction parameter Methane to calculate methane concentrations and distribution through the ventilation network 3 5 MineFire Control Data MineFire allows the user a level of control over the simulation and the Control Card screens are the means by which the user enacts that control The Control Data I screen asks for iteration limits time span limits reference air properties and modes of calculations and output The Control Card II screen requests reference junction properties calculation accuracies and warning limits It also allows the user to regulate how the program sets the limits of the fan curve s Both screens provide Set Default buttons that provide base levels or typical values that will give the user a starting point for determining the inputs 3 5 1 Control Data I The Control Data I card regulates how the program calculates the fire or event sequence in the network Iteration and time parameters are entered here as well as reference properties of the air and modes of calculation and program output The Control Data I screen is shown in Figure 5 below Note that all values with the exception of Reference Density must be entered as integer values The grayed out parameters signify fixed values in MineFire at this time 19 Control Cards MFire Control Data I MFire Control Card II Number of Branches Select Calculations Ze Complete All Calculations
81. showing miners or other personnel the effects of fire on the system or on a localized area As with VnetPC proposed ventilation networks may be evaluated using MineFire Such simulations are conducted by incorporating physical input data from conceptual plans with documented design parameters used to determine estimated resistances for airways in the network The range of fan duties required airflows pressure drops operating costs the location of ventilation controls and theoretical effect of the addition of heat to the system may be ascertained for the selected time of study by conducting time phase exercises Options within the VnetPC platform allow for the display and manipulation of three dimensional networks production of listings and output files and plots of input and output data 2 2 Program Description and Background MineFire was adapted from the MFire code from the former US Bureau of Mines the most recent version available was version 2 20 from 1995 into a user friendly format within the VnetPC interface The only modifications to the code increased the branch and fan limits so as to increase its usefulness in the modern mining industry and to allow the programs to compile in a Windows environment The MFire routines were then tied into the VnetPC shell with pre and post processors The calculation portion of the program consists of four sub programs The first is a batch file that controls the executions of subsequent program
82. t every site has its own unique setup MVS can only provide support for LAN networks If any problems are encountered please contact us MVS can be reached at Telephone 559 452 0182 Facsimile 559 452 0184 Email support mvsengineering com 2 8 Differences between MineFire and VnetPC There are differences in how MineFire and the calculation code within VnetPC operate MineFire calculates the network based on mass flow balance and as such airflows may not exactly balance while VnetPC calculates based on a volume flow balance MineFire considers changes in density in the calculation process which allows the program to evaluate the effect of thermal disparities on a mine ventilation system VnetPC assumes constant air density and significant changes in density are handled by injecting or 10 rejecting a portion of the airflow quantity associated with the density change Effects of natural ventilation pressure are handled in VnetPC with the insertion of a fixed pressure fan in the relevant shaft or entry The calculation packages are similar in that they model the ventilation system of underground facilities using simplified ventilation networks to represent the underground airways Both utilize Kirchoff s Laws and the Hardy Cross iterative method to calculate the network 2 9 Program Limitations The MineFire program has limitations placed upon it so that execution times can be minimized Similar to VnetPC MineFire has a limit of
83. t of time The units are ft min or m sec 3 3 2 Branch Average Values MineFire includes a screen where average values may be entered for these parameters plus rock conductivity and diffusivity It is reached through the MineFire menu option The values are entered and may be toggled on or off for use in the simulation and will replace blank zero values that are left in the input data The accuracy of the model will 16 suffer compared to the use of location specific data within the model This screen is shown in Figure 3 below MFire Average Values E ft 2 hr puten Det Ibm min 2 t Set Defaults ft Thermal Diffusivity of Rock Thermal Conductivity of Rock Friction Factor Lenath of Airway Sectional Area of Airway 2 DD Perimeter ft Use Average Values in MFire simulation Figure 3 MineFire Average Values Screen 3 3 3 Branch Data Formats MineFire recognizes four branch data formats through the VnetPC platform The available branch types may be accessed in the Branch Input View from a drop down list under the appropriate column for each branch The branch data types are entered in the Schematic View using the Selection Pointer tool Tools Menu or Tools Bar and pressing the right mouse button select the Branch Data option or by using the Edit Tool Tools Menu or Tools Bar Each branch is defined by two junctions and by numerical data that indicate the characteristics o
84. tal to the simulation and others simply provide warnings to the user in other words the program will do its best to interpret the data the user provides Even if an error has been identified in a branch the program will continue execution until it encounters a fatal error that terminates its operation Non fatal errors may or may not allow the program to converge on a solution Upon execution of the MFire kernel a pop up window will appear telling the user the program executed with or without errors If errors occurred a text output of the mfire tmp file which includes a list of errors and the data output is provided A sample of this output is given in Figure 14 If the text output does not appear automatically it can be accessed from the MFire Results option under the MineFire Menu A number of common errors may be encountered by the user Some of these are described below A more complete list is provided in the Help files under Errors File Edit Format View Help ERROR CAPACITY OF SURFACE JUNCTION ARRAYS EXCEEDED CURRENT INPUT JAN 80 IMX 15 THE FOLLOWING IS THE CRITICAL DATA READ IN SO FAR NO J5 JF NWTYP R Q KF LA A o 15 z 4 Q 0 018 1000 Q 500 100 0 50 0 14 lil 7 Q 0 023 1000 Q 500 100 0 50 0 13 23 11 Q 0 008 1000 Q 500 100 0 50 0 12 33 23 Q 0 007 1000 Q 500 100 0 50 0 11 13 33 o 0 014 1000 Q 500 100 0 50 0 10 19 13 Q 0 015 1000 Q 500 100 0 50 0 Figure 14 Mfire tmp Text Ou
85. the curves are converted if the unit conversion utility is enabled See section 3 4 and 3 5 in the VnetPC Pro User s Manual for a more detailed discussion MineFire uses the cubic spline method to smooth the fan curve This is a departure from VnetPC which simply assumes a straight line between points on the fan curve which the user enters This straight line method has returned acceptable results but original MFire code took the calculations a step farther Generally the spline method is thought to be superior for network problems compared to least squares smoothing or other methods Since MineFire assumes compressible flow the use of inject and reject branches is not recommended except where absolutely necessary to balance the basic Initial network The effects of auto compression and ventilating energies are accounted for by MineFire based on the temperature elevation and density values input by the user 25 3 7 Contaminant Data The MineFire Contaminants function is the core of the MineFire input data It defines the fire or event that the user is attempting to simulate and is used to enter the fire s or event s and the associated variables and parameters that are affecting the ventilation system Following execution of the simulation a symbol is inserted to represent the location of the fire or event Figure 9 140 Figure 9 MFire Fire Event Symbol Before calculating or otherwise selecting any paramet
86. to be converted from VnetPC for Windows has coordinates specified for all the junctions in the network If the user has not specified coordinates for all the nodes then errors will appear when the file is opened 4 3 Execute MineFire Kernel To run the MineFire simulation first close all the input and results views and then select the Execute MineFire kernel option from the MineFire Menu on the menu bar This should only be done when the junction branch fan temperature methane and rock thermal data for the network have been fully entered When the program has finished execution a window will open containing the mfire tmp file if any errors have occurred If the run is successful an OK box will be presented to the user indicating the simulation is complete and each view will be updated with the current information The initial network non steady state simulation and quasi equilibrium network are viewed on the schematic using the Data Phase pull down menu included the Schematic View menu bar The Non Steady State data phase includes a slide show Record Select viewer so that the user may watch the progression of the fume front through the mine and the change in the ventilation parameters over a selected period of time This is shown in Figure 12 The Record Select viewer disappears when the Initial or Quasi Equilibrium Data Phases are selected 30 4 4 Viewing the Results of a Simulation Once the program has
87. tput 4 4 1 1 Capacity of Surface Arrays Exceeded This error occurs because unlike VnetPC MineFire requires all branches be in closed loops The error may occur if any dead end branches exist in the model In addition VnetPC handles surface junctions like shaft collars with branches set to surface intake or exhaust by creating hidden branches to a dummy atmosphere node MFire does not account for the surface intake and surface exhaust branches in the same way The solution in MineFire is to draw in the dummy node and branches to shaft collars and portals This dummy node number or one of the surface nodes must be set as the Starting Junction in the MFire Control Card II and the Reference Junction in the Model Information View Figure 15 and Figure 16 below indicate the problem and the solution to the surface arrays exceeded error 32 EUM of 92 88 Figure 15 Shaft portal arrangement resulting in error Figure 16 Shaft portal arrangement corrected 4 4 1 2 Dead end Branches Similar to the error described in 4 4 1 1 if loops are left un closed in the model the Junction is a dead end error will occur indicating that dead end branches or unclosed loops exist Closing the loops or eliminating unneeded branches will solve this error 33 4 4 1 3 Fan Errors No Fan in Network This warning may occur in conjunction with other errors If fans have been entered properly it c
88. ts Non Steady State Data Phase AAA 49 Figure 32 Small Shaft Mine Example sese nennen rennen nre 50 Table 3 Example Rock Property Data 50 Figure 33 Example geothermal step Puncton nennen rennen 51 Figure 34 Wood Shaft Mine sample 54 Figure 35 Gas emission versus temperature for wood SI 56 Figure 36 Gas emission versus temperature for wood Imperial eeeeseeeeereeeresreeresrrrrssreersre 56 Figure 37 Coal Mine Example er mage tete ee pet eee Pee e Ee AER et 59 Table 1 Branch Data Types List of Tables Table 2 Branch Parameters by Data Phase Table 3 Example Rock Property Data 1 Introduction Welcome to the MineFire software Program This is a Microsoft Windows application to be used in conjunction with VnetPC Pro It is designed to simulate a mine ventilation system s response to external influences such as fires The Program was built from the former US Bureau of Mines MFire code which was modified by MVS solely to increase the number of branches and fans available and to run in Windows This calculation kernel was then adapted into the user friendly interface of Mine Ventilation Services VnetPC ventilation software package for use primarily as a training tool MineFire performs ventilation network planning calculations and dynamic transient state modeling of ventilation networks under a variety of conditions The Program simulates a system s response to altered v
89. ts for fans Imperial and SI units with full data conversion Automatic allocation of surface branches to close meshes around surface nodes Notepad to enter detailed description of simulation Full annotation capabilities in all views allows angled text Automatic calculation of branch length from coordinate values Regulator orifice sizing tool Pure 32 Bit application with rapid execution times Default network size limit is 500 branches with 10 fans Extensive Help Tool Full online support at www mvsengineering com Direct graphic printing and multi colored plotting Slide show for time series viewing of fume fronts Export DXF files to CAD and mine planning programs multiple layers Four input data types for branch resistance Steady state contaminant distribution analyses Fixed quantity tool Color coding of branches for range of parameter airflow pressure etc Cut copy paste features for data exchange within Windows Notepad error display 2 5 Recommended System Requirements for MineFire VnetPC PC Running Windows XP SP2 Vista or Windows 7 Pentium II class processor or AMD Equivalent or better 512 MB RAM e 500 MB Hard Disk Space for the MineFire program and models additional for Adobe Acrobat Reader e Available USB slot for HASP Key Not required for network version 2 6 Setup Procedure You the end user have received the MineFire program on a CD or a thumb drive along with a HASP Key All MVS software is also availab
90. tu lb value is given as an average of the metric values 20 2 Material M kg Btb Blasting powder f 385 16552 Butane Cain 495 20081 Cabon S o ase uw Coal anthracite 305 342 13 908 Coal bituminous 236352 12640 Diesel fuel wg 19390 Dynamite fo o 54 2322 Epoxy Jf 311314 13435 Ethanol So 2967 12556 FuelOil No Le 19819 Fuel Oil No 6 LL 425 18272 Gasoline 437 18788 Kerosene f 433 18616 Lignin C mo 247264 10985 Lignite Jf 224333 11973 Nylon La 13285 Nylon 11 Rilsan 3699 15903 Octane Cog J 479 20593 Polyester chlorinated L 1784 7670 Polyester f 216298 11049 Polystyrene 414425 18035 Polystyrene foam 397 17068 Polystyrene foam FR 412 429 18078 Polyurethane 239 10275 Polyurethanefoam 261316 12403 Polyurethane foam FR Lan 10 533 Polyvinyl chloride Las 7717 Polyvinyl chloride foam 2283 9815 Propane C3 a soss 20647 Rubber bunaN 347356 15112 Rubber butyl Los 19690 Rubber GRS Lu f 19003 Rubber isoprene natural 449 19304 Rubber latex foam 339 406 16015 Rubber Tire auto rucbk 326 14015 Silicone Rubber Lies 6943 Silicone Rubber foam 14 0 495 7201 Styrene 2231 18147 Wood Douglasfir 21 9028 Wood Oak 202 8684 Wood Spruce JL 218 9372 Wood White
91. uming that the contaminants have worked their way through the system into a steady state form The default value is 10 hours Accuracy in Calculation Parameters The accuracy control cards are helpful for the user in depending on how detailed a particular modeling effort has to be relative to speed of simulation versus the precision of data The higher levels of accuracy demand more calculations by the processor Default values are 0 005 for contaminants 0 01 for methane and 0 1 F for temperature Warning Criteria Parameters The warning criteria allow the user to set limits on critical parameters and when they are exceeded junctions and branches that contain values outside of the specified range will be listed in the text output for each time period This is useful for finding out when sections of the mine become hazardous Refer to Figure 7 below The Pressure Drop warning criteria is the only lower limit Its default value is 0 01 in w g Methane and Fume contaminant Concentration and Temperature warning criteria are upper limits The methane default value is 1 0 The fume default value is 0 05 The high temperature default is 100 0 F Boundary Range for Fan Curves This selection tool allows the user to choose the method by which the program terminates the fan curve beyond the range of points that the user has input Refer to Section 3 6 Fan Data below 22 IN THE FOLLOWING AIRWAYS EXIST CRITICAL CONDITIONS AIRWA
92. user to select the time phase the data is displayed in once the MineFire kernel has been executed The Initial phase starts at time 0 of the fire or event the system has not yet taken the event into consideration Non Steady State phase looks at the fire or event at intervals and during based on parameters the user entered in the Control Cards The Quasi Equilibrium phase looks hours into the event based on a parameter the user entered in the Control Cards This assumes that the system has approached or completed the transition into an equilibrium condition and is in its final state either the fire has consumed its fuel and burned out or is continuing in steady state The Branch Parameter pull down menu item allows the user to display various parameters based on the data phase selected The table below summarizes the parameters shown in the various data phases 36 The Junction Parameter pull down menu item allows the user to display Temperature Fumes Methane or no data Table 2 Branch Parameters by Data Phase Initial Non Steady State Quasi Equilibrium None None None Airway Airway Airway Resistance Delta Q Change in Airflow Resistance Airflow Airflow Airflow Headloss Average Temperature Headloss Rock Temperature Temp at end of branch Rock Temperature Methane Production Fumes Methane Production Conductivity Methane Conductivity Diffusivity Headloss Diffusivity 4 4 2 1 A
93. w all groups layers in the current view View only the selected groups layers in the current view 71 8 Appendix B Heat Transfer Sample Calculation The following sample calculation was performed for a hypothetical diesel fuel fire in a small shaft mine Assume 55 gallons of diesel fuel in a 3 inch deep pool The density of diesel fuel 61 Ib ft 2 Burn rate 0 12 inches of fuel depth per minute 2 Heat release 19390 Btu Ib from the table 2 3 55gal ae 7 35 ft diesel fuel 1 7 35 ft 29 4 ft area of pool LEE ES f Pon 3 Heat Release Rate PARL TORUM A eee 11827 9Btu min ft 12in ft Heat Transfer 11827 9 Btu min ft 29 4 ft 2 347 740Btu min 12 9 Appendix C Calculating Air Fuel Ratio Using typical gasoline petrol as an example we will show how to determine the fuel air ratio of a combustible substance Petrol is a complicated mixture of many different hydrocarbons including alkanes cycloalkanes alkenes cycloalkenes and arenes such as benzene and methylbenzene One gram of each of these compounds requires a different mass of air for complete combustion the stoichiometric ratio depending on the molar mass of the compound the number of oxygen molecules required for complete combustion and the proportion of air that is oxygen For example the equations for complete combustion of a representative range of hydrocarbons found in petrol ar
94. y diffusivit Dynamic 1 lb ft s 1 488 16 Ns m2 hol 0 671 97 viscosit 79 Imperial to S i Sito Imperial Thermal 1 F ft 1 8227 C m 1 C m 0 5486 EN NE nd SE a content tg 1 00001429 kgkg 1 1 7000 gb Gay 1Gmy 2100 E j1Cuie 237x109 Bq 1Bq 27 x 10 12 Sv 18v SI rem gt C kg Roentgen i 1 C kg z 3876 ge fe Bq 1 1 Roentgen 2 58 x 10 4 Ld e VE i Temperature K C 273 15 F 459 67 For actual temperature 1 8 x t C 32 F Dei 9 CITT 1 8 mm For differential temperatures 1 Centigrade degree 1 8 Fahrenheit degrees 80 13 Appendix G References 1 Bureau of Mines Circular 41C9245 A User s Manual for MPIRE A Computer Simulation program for Mine Ventilation and Fire Modeling by Xintan Chang Linneas W Laage and Rudolf E Greuer 1990 2 Bureau of Mines Circular 1C9154 Computer Modeling of the Effect of Mine Fire Induced Ventilation Disturbances on Stench Fire Warning System Performance by Linneas Laage William Pomroy and Thomas Weber 1987 3 Bureau of Mines Report RI9076 Calculating Fire Throttling of Mine Ventilation Airflow by Charles Litton Maria DeRosa and Jing Shu Li 1987 4 Bureau of Mines Circular IC8901 Real Time Calculation of Product of Combustion Spread in a Multilevel Mine by John C Edwards and Rudolf E Greuer 1982 5 Fire Protection H
95. y state portion of the simulation to return the calculated results and display the dynamic simulation The default is 30 seconds Time Span of Dynamic Simulation This is the length of the non steady state portion of the simulation or the total length of time that the fire or event is displayed and calculated The default is 5 minutes displayed as 300 seconds 20 Time Interval for Output Allows the user to specify the output time periods of the text results The value should be the same or a multiple of the Time Increment in Dynamic Part value Reference Temperature of Air and Reference Density These parameters are used in determining NVP and ventilating energies in the network They should be provided for the Reference Junction for average surface atmospheric conditions Select Calculations In this release only allows the Complete All Calculations option MFire Output In this version the program only allows the Detail option 3 5 2 Control Card II The Control Card II screen contains the definition and air temperature of the starting junction at surface time to reach equilibrium program accuracy parameters and user controlled warning parameters The Control Card II screen is shown in Figure 6 below Control Cards MFire Control Data MFire Control Card II Starting Junction Atmosphere Set Defaults 0 Degrees F Temperature at Start Junction Time Span to assume Quasi equili
96. ygen concentration 2 350 cfm O 15 269 cfm total 15 4 58 6 3 Coal Fire Example A power center just outby the new Continuous Miner section placed in a crosscut opposite the intake to the section branch 37 15 malfunctions and ignites This sets the coal on fire before passing miners can contain the blaze The mine is located in Kentucky the No 9 Mercer bed Entries average 5 high by 20 wide The characteristics of the coal determined from analysis of coal samples are given below Density 850 kg m 84 Ib ft Heat Value 12 080 Btu Ib Sulphur 3 5 Hydrogen 5 6 Carbon 66 9 Oxygen 13 1 Ash other 10 9 Time 0 airflow in the power center cross cut branch 37 15 1100 cfm Time 0 airflow in the intake airway inby the cross cut branch 37 38 58 300 cfm Time 0 airflow in the CM section intake branch 37 48 65 700 cfm Figure 37 Coal Mine Example 59 Heat basis of fire 1100 cfm x 21 O x 0 075 lb ft 17 3 Ib min O2 available for combustion Assume 100 ventilated 1 Determine the air fuel ratio of coal refer to Appendix C First consider coal as a hydrocarbon and analyze any oxygen consuming reactions for complete combustion S 02 gt SO Moleweight of Sulfur 32 g mol H2 1 2 02 2 H2O Moleweight of Hydrogen 2 g mol C 0 gt CO Moleweight of Carbon 12 g mol Determine the Mass of air to combust each component S 1 32 g mol S x 1 mol O2 x 32 g

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