Marley class 800 mechanical draft cooling tower user manual
Contents
1. Bearings overgreased Remove grease reliefs Run motor up to speed to purge excessive grease Rotor rubs stator bore If not poor machining replace worn bearing Wrong lubricant in bearings Change to proper lubricant See motor manufacturer s instructions One phase open Stop motor and attempt to start it Motor will not start if single phased Check wiring controls and motor Poor ventilation Clean motor and check ventilation openings Allow ample ventilation around motor Winding fault Check with Ohmmeter Bent motor shaft Straighten or replace shaft Insufficient grease Remove plugs and regrease bearings Deterioration of grease or foreign material in grease Flush bearings and relubricate Bearings damaged Replace bearings Motor Does Not Come Up Incorrect fan blade pitch See Fan User Manual for blade pitching instructions T d 7 Voltage too low at motor terminals because of line drop Check transformer and setting of taps Use higher voltage on transformer terminals or reduce loads Increase wire size or reduce inertia Broken Rotor bars 22 Look for cracks near the rings A new rotor may be required Have motor service person check motor Troubleshooting Trouble Cause Remedy Wrong Rotation Motor Wrong sequence of phases Switch any two of the three motor leads Geareducer Noise Geareducer bearings2. Hz Special Info Volts Action Required Action Required Action Required 27 SPX COOLING TECHNOLOGIES 7401 WEST 129 STREET OVERLAND PARK KANSAS 66213 UNITED STATES 913 664 7400 spxcooling ct spx com spxcooling com In the interest of technological progress all products are subject to design and or material change without notice 2009 SPX Cooling Technologies Inc Printed in USA Manual 95 1356A
3. Marley Class 800 Mechanical Draft Cooling Tower f User Manual 95 1356A uM Marley A Warning A Caution Note Notice The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk levels or to important information concerning the life of the product Indicates presence of a hazard which can cause severe personal injury death or substantial property damage if ignored Indicates presence of a hazard which will or can cause personal injury or property damage if ignored Indicates special instructions on installation operation or maintenance which are important but not related to personal injury hazards These instructions assist in obtaining efficient long life from Marley cooling equipment Direct questions concerning cooling tower operation and maintenance to your Marley sales office or representative Always include your tower serial number when writing for information or ordering parts Look for this number on the nameplate near the access Contents Generals aenean DU eA ua mE 4 Before StartUp ERR 5 Initial Starting Procedure centre trii errante 7 Routine Starting Procedure sees tententnntnntettnntennanis 8 Opetatlori uem roto ede ed ata b deu td 9 Freezing Weather Operation esses sesenta trenta tnn tette ttt tatis 11 Temperature Control and Energy Management
4. at full or half speed or all fans must be operated in reverse Allow a minimum of 10 minutes delay between reverse operation and forward operation during subfreezing weatherto permit ice to dissipate from fan blades and fan cylinders With no heat load on the circulating water icing cannot be controlled effectively by air control alone during freezing weather Towers must not be operated with reduced water rate and or no heat load during freezing weather If a bypass directly into the cold water basin is used all water must be bypassed Water flow over the tower must never be modulated during freezing weather See Drive on pages 9 and 10 forfan speed change and reversing precautions Intermittent Operation When the unit is operated intermittently during winter weather it is necessary that the water be drained from the tower piping to insure protection against freezing and possible rupture Temperature Control and Energy Management The wet bulb temperature of the ambient air varies significantly on a daily basis and considerably from season to season As the wet bulb temperature reduces the tower becomes capable of producing colder and colder water or it becomes capable of producing a given cold water temperature at reduced airflow through the tower These characteristics are the opposing forces referred to on page 4 Maximizing Tower Performance If your operating system is one which benefits from the coldest possi
5. Check drive shaft alignment Realign if necessary See Marley Drive Shaft User Manual Check tightness of bolts that attach mechanical equipment support to the tower structure Check tightness of bolts in fan cylinder joints and fan cylinder anchorage Check concrete structural surfaces for spalling and cracks Repair as necessary Check tightness of the following bolted joints in the fan and drive assemblies Fan hub clamp bolts See Marley Fan User Manual for correct torque setting Fan hub cover bolts where applicable Geareducer and motor mounting bolts Drive shaft coupling and guard bolts e Check Geareducer oil for sludge or water by draining off and testing a sample as outlined in the Marley Geareducer Service Manual Check Geareducer oil level at oil level mark on the side of the case Add oil as required The oil level placard must be adjusted so that its full mark is at the same elevation as the full mark on the side of the Geareducer case Check oil lines to be sure there are no leaks and all joints are tight See Geareducer User Manual for oil filling procedure and list of recommended lubricants A Caution Before Start up Rotate fan by hand to be sure of free rotation and ample tip clearance See Marley Fan User Manual e Check motor insulation with a Megger See maintenance section of Marley Electric Motor Service Manual Lubricate the motor according to motor manufacturer
6. If new see if noise disappears after one week of operation Drain flush and refill Geareducer See Geareducer Service Manual If still noisy replace Gears Correct tooth engagement Replace badly worn gears Replace gears with imperfect tooth spacing or form Unusual Fan Drive Vibration Loose bolts and cap screws Tighten all bolts and cap screws on all mechanical equipment and supports Unbalanced drive shaft or worn couplings Make sure motor and Geareducer shafts are in proper alignment and match marks properly matched Repair or replace worn couplings Rebalance drive shaft by adding or removing weights from balancing cap screws See Drive Shaft Service Manual Fan Make certain all blades are as far from center of fan as safety devices permit All blades must be pitched the same See Fan Service Manual Clean off deposit build up on blades Worn Geareducer bearings Check fan and pinion shaft endplay Replace bearings as necessary Unbalanced motor Disconnect load and operate motor If motor still vibrates rebalance rotor Bent Geareducer shaft Check fan and pinion shaft with dial indicator Replace if necessary Fan Noise Loose fan hub cover Tighten hub cover fasteners Blade rubbing inside of fan cylinder Adjust cylinder to provide blade tip clearance Loose bolts in blade clamps Check and tighten if necessary 23 24 Safety The tower has been d
7. s instructions Testrun each fan separately for a short time Check for excessive vibration or unusual noise If either is present see Troubleshooting on pages 22 and 23 of this manual Fan must rotate clockwise when viewed from above Recheck Geareducer oil level Check functioning of make up water supply Make sure the blowdown or bleed off will carry the proper amount of water See Blowdown on page 18 Operate Water System Complete steps 1 thru 4 under Initial Starting Procedure on page 7 Circulate water over the tower continuously for several days before starting the mechanical equipment and putting the tower into continuous operation Do not circulate water over the tower in freezing weather without a heat load See Caution note on page 8 A Caution Initial Starting Procedure 1 Fill the cold water basin and circulating water system to a level 1 2 13 mm below the overflow 2 Bypass valve should be closed unless start up is in cold weather See Routine Starting Procedure on page 8 3 Prime and start the circulating water pumps one at a time Increase the flow of circulating water gradually to design water rate to avoid surges or water hammer which could damage the distribution piping 4 When flow has stabilized at or near the design rate adjust water make up to maintain the level that the water has pumped down to in the cold water basin See Cold Water Collection Basin on page 10 This should c
8. vents are open S 5 Lubricate grease R S 6 Check oil seals M 7 Check operating oil level D 8 Check static oil level M 9 Check oil for water and sludge M 10 Change oil S 11 Check fan blade tip clearance S 12 Check water level 13 Check for leakage W 515 5 14 Inspect general condition 51515 5 5 Y S Y S S S Y S S S 15 Tighten loose bolts 5 515 115 YIRIS 16 Clean RIRIRIRIRIRISIRIRIRAR 17 Repaint R RIRR 18 Rebalance R R 19 Completely open and close S 20 Inspect repair for safe use Y Y Y R 21 Inspect and repair before each use D Daily W Weekly M Monthly Q Quarterly S Semi annually R As Required 25 Inspection Checklist Date Inspected Owner Owner s Tower Designation Inspected By Tower Manufacturer Process Served by Tower Design Conditions GPM HW Number of Fan Cells Location Model No Serial No Operation Continuous Intermittent Seasonal F CW F WB F Condition 1 Good 2 Keep an eye on 3 Needs immediate attention Structure Casing Material Structural Material Fan Deck Material Comments Stairway Material Ladder Material Handrails Material Interior Walkway Material Cold Water Basin Material Water Distribution System Distribution Basin Material Inlet Pipe Material Inlet Manifold Material F
9. 13 Maintenance 15 IIT 17 Water Ireattmient cote cric etti ne oerte uad 18 Seasonal Shutdown Instructions sse tenen 20 Spare Parts and Accessories seen 21 Troubleshooting eme 22 IL e RlGI IM LM 24 Inspection and Maintenance 25 Inspection Checklist 26 General A cooling tower like any heat exchanger exchanges all heat imposed upon it from one fluid to another fluid For a cooling tower heat from the water is put into the air The plant process replenishes the heat to the water typically at another heat exchanger such as a condenser A cooling tower differs from many heat exchangers in that heat is transferred two forms sensible and latent heat As heat is transferred from the water the air temperature increases sensible and the air s water content or humidity also increases latent As the heat load inlet air wet bulb temperature or airflow on a cooling tower changes the cooling tower will respond by finding a new equilibrium with the process The cooling tower will still dissipate all the heat from the process but at new water temperatures The cooling tower cold water temperature is the supply water temperature to the condenser and changes in the cold water temperature usually affect effic
10. 2 F 0 C or below do not put cold water on tower Mechanical Equipment Shutdown for less than 3 months Each month drain water condensate from the lowest point of the Geareducer andits oil system Check oil level and add oil if necessary Operate Geareducer briefly to recoat all interior surfaces with oil At start up drain water condensate and check oil level Add oil if necessary Refer to Geareducer User Manual for maintenance and lubrication instructions Shutdown for 3 months or longer Ifthe motors have space heaters operate mechanical equipment one hour each month Space heaters should be energized anytime motor is not operating If the motors do nothave space heaters operate mechanical equipment one hour each week At start up operate mechanical equipment one hour or until oil is warm then shut the equipment down Drain the oil and refill with new oil Refer to Geareducer User Manual for instruction on changing oil Refer to Marley Downtime User Manual for downtime of 6 months or longer Electric Motors Do not start motor without determining that there will be no interference with free rotation of the fan drive Refer to Marley Electric Motor User Manual If shutdown period is longer than seasonal contact your Marley sales office or representative for additional information Spare Parts and Accessories Spare Parts SPX Cooling Technologies manufactures and maintains a stock of replacement parts for all coolin
11. ble water that is if colder water allows you to increase your output or allows you to operate your system at significantly lower cost then continuous full speed operation of the fan s may be your best mode of operation In this mode of operation concern for the cold water temperature level would be limited to the potential for the tower to form ice during freezing weather See Caution note on page 8 and Freezing Weather Operation on pages 11 and 12 Although the 70 F 21 C cold water temperature indicated on page 11 is appropriate for cold weather start up and operation acceptable temperatures during full operation in spring summer and fall may be appreciably lower perhaps as low as 50 F 10 C or less Refer to your performance curves for expected tower cold water temperatures at varying flow rates ranges and wet bulb temperatures Minimizing Tower Energy Use Most systems gain no operating or production benefits from watertemperatures below a certain level and that level is not usually below the aforementioned 70 F 21 C When a reducing ambient wet bulb permits the tower to reach that target cold water temperature level further reductions in the wet bulb temperature permit manipulation of fan speeds or operation to maintain that temperature level Single speed fans can be cycled on and off for cold water temperature control with the steps of control depending upon the number of fan cells in the tower Two speed motors off
12. ce See the Inspection Checklist on pages 26 and 27 in this manual Keep a continuous lubrication and maintenance record for each cooling tower Conduct regular inspections repair personnel safety items items 20 and 21 in the table on page 25 and maintain records of all this is especially important For a supply of check list forms contact your Marley sales office or representative Hot Water Distribution System Keep the circulating water and distribution system piping and nozzles clean andfree of dirt algae and scale Algae and scale may clog nozzles eliminators fill and piping and may collect on the equipment served thus reducing its performance See Caution note below under Fill Access The optional access door in the fan deck with an optional short ladder to the top of the fill provides a means for inspection of the plenum area above and below the eliminators Removal of eliminator packs allows access to the spray chamber for inspection and maintenance of the nozzles and top of fill Under no circumstances are the eliminators to be used as a walking surface Provide top surface protection before walking on the fill Fill Clean free flowing unobstructed fill is key to the continued efficient operation and performance of a cooling tower The owner operator must keep the circulating water clean by treatment screening or filtering to avoid the possibility of fill clogging Sea water if used willtypically present inc
13. condenser but may occur in the fill because of CO stripping e Silica scale is virtually impossible to remove However silica scale is unlikely if concentrations of SiO are held below 150 ppm Oxides such as iron oxide can coat all parts of the system if soluble iron is present in concentrations above 0 5 ppm Iron oxides do not usually develop into thick scales but like mud can accentuate the development of other scales Foaming Heavy foaming sometimes occurs when a new tower is put into operation This type of foaming generally subsides after a relatively short period of operation Persistent foaming can be caused by the concentrations of certain combinations of dissolved solids or by contamination of the circulating water with foam causing compounds This type of foaming can sometimes be minimized by increasing the blowdown but in some cases foam depressant chemicals must be added to the system Foam depressants are available from a number of chemical companies 19 A Caution 20 Seasonal Shutdown Instructions Tower Drain all tower piping During shutdown clean the tower and make any necessary repairs Apply protective coating as required to all metal parts Particular attention should be given to mechanical equipment supports drive shaft and drive shaft guards Geareducers and motors See Warning note on page 17 regarding tower cleaning Visually inspect for concrete deterioration If ambient temperature is 3
14. eareducer Make weekly and monthly oil checks Inspect internal parts during seasonal oil change Refer to the Geareducer User Manual for detailed maintenance instructions Cold Water Collection Basin Inspect collection basin occasionally for cracks leaks and spalling and repair if necessary Maintain a positive Langelier index in your circulating water See Water Treatment on pages 18 and 19 Keep cold water outlets clean and free of debris Make up and circulating water controls must operate freely and maintain the desired water quantity in the system A Warning Cleaning Anyevaporative type cooling tower must be thoroughly cleaned on a regular basisto minimize the growth of bacteria including Legionella Pneumophilla to avoid the risk of sickness or death Service personnel must wear proper personal protective equipment Do NOT attempt any service unless the fan motor is locked out Operators of evaporative cooling equipment such as water cooling towers should follow maintenance programs which will reduce to an absolute minimum the opportunity for bacteriological contamination Public health service officials have recommended that good housekeeping procedures be followed such as regular inspections for concentrations of dirt scale and algae periodic flushing and cleaning and the following of a complete water treatment program including biocidal treatment Visual inspection should take place at least once a week d
15. er from the process flows through an inlet to each cell which supplies a distribution header and a system of branch arms and nozzles Each distribution header may be equipped with a vent standpipe to minimize water hammer to maintain a slightly pressurized water distribution system and to provide vacuum release at pump shutdown If an Amertap condenser tube cleaning system is part of plant equipment care should be taken during operation to back wash the strainer section only after the sponge rubber cleaning balls are removed from the system by trapping them in the collector Balls that are allowed to enter the cooling tower supply piping may clog some of the nozzles although the generous flow paths through the nozzles make this unlikely However balls escaping the nozzles will accumulate on top of the fill ultimately causing unequal water distribution that will affect thermal performance The top of the fill should be frequently checked until such time as the operational sequence of the Amertap system assures that no balls enter the cooling tower distribution system Fill Water leaving the nozzles is scattered uniformly over the fill plan area The water flows through the fill coating each fill sheet to maximize water surface exposure to the air being moved by the fans Drift Eliminators Air leaving the fill passes through a level of drift eliminators covering the entire plan area of the tower The purpose of these drift eliminators is t
16. er is not on all leads at starter make sure overload and short circuit devices are in proper condition Wrong connections Check motor and control connections against wiring diagrams Low voltage Check nameplate voltage against power supply Check voltage at motor terminals Open circuit in motor winding Check stator windings for open circuits Motor or fan drive stuck Disconnect motor from load and check motor and Geareducer for cause of problem Rotor defectve Look for broken bars or rings Unusual Motor Noise Motor running single phase Stop motor and attempt to start it Motor will not start if single phased Check wiring controls and motor Motor leads connected incorrectly Check motor connections against wiring diagram on motor Ball bearings Check lubrication Replace bad bearings Electrical unbalance Check voltages and currents of all three lines Correct if required Air gap not uniform Check and correct bracket fits or bearing Rotor unbalance Rebalance Cooling fan hitting guard Reinstall or replace fan Motor Runs Hot Wrong voltage or unbalanced voltage Check voltage and current of all three lines against nameplate values Overload Check fan blade pitch See Fan User Manual Check for drag in fan drive train as from damaged bearings Wrong motor RPM Check nameplate against power supply Check RPM of motor and gear ratio
17. er twice as many control steps with the added bonus that half speed which produces half of the normal airflow through the tower requires less than 20 of the full speed power requirement 13 A Caution 14 Temperature Control and Energy Management Excessive cycling of motors causes overheating of the windings and ultimate failure of the motor The total amount of starting time period of high inrush current should not exceed 30 seconds per hour On fans 20 feet diameter and smaller this may allow 4 or 5 starts per hour On larger fans 1 or 2 starts per hour may be the limit Determine the number of seconds it takes your fan to get to full speed by observation and divide that number into 30 to obtain the recommended maximum number of starts per hour Two speed motors cycling between halfandfull speeds permit acommensurately greater number of control cycles Variable frequency drives of course provide the ultimate in both temperature control and energy management and can be easily retrofitted to your system Please discuss this with your Marley representative Note A Warning A Caution Maintenance Well maintained equipment gives the best operating results and the least maintenance cost A regular inspection schedule is recommended to insure effective safe operation of the cooling tower Use the Inspection and Maintenance Schedule on page 25 to obtain continuously good performance with least tower maintenan
18. esigned to provide a safe working environment while either operating or shut down The ultimate responsibility for safety rests with the Operator and Owner When flow to the tower is shut off or when portions of the tower require maintenance temporary safety barricades may be required around openings Other safety precautions such as safety harnesses should be utilized where appropriate for compliance with OSHA regulations and standards and good safety practices Routine periodic maintenance must be performed on all personnel access and material handling accessories in accordance with the following schedule Ladders Stairways Walkways Handrails Covers Decks and Access Doors Davits Derricks and Hoists Inspect for General Condition Semi annually Semi annually Repair for Safe Use As Required As Required Inspection and Maintenance Schedule General Recommendations More frequent inspection and maintenance may be desirable Stairs Ladders Walkway Doors Handrails E E 5 o EF L T o O 2 g 2 S 6 2 56 9 9 m a T 9 96 5 85 2 E s S 202 o3u Sgi c 2 Se 5 S 9 5 9 c 3 Li 200n0io0ic cuoooov od 1 Inspect for clogging M M W 2 Check for unusual noise or vibration DIDID 3 Inspect keys keyways and set screws SISJ SJ S 4 Make sure
19. ex and predict the corrosive tendencies of the tower water toward concrete An explanation and method of calculating the Langelier index can be found in all books on water treatment Maintaining a positive Langelier index provides excellent protection of concrete Slime a gelatinous organic growth and algae a green or brown plant growth may grow in the cooling tower or heat exchangers Their presence can interfere with cooling efficiencies Proprietary compounds are available from water treating companies for the control of slime and or algae however compounds which contain copper are not recommended Chlorine if used should be introduced at a point in the circulating water system that will promote rapid dispersal and residual chlorine should not exceed one part per million parts water 1 ppm Scaling Scale can be caused by the uncontrolled presence of sulfates silicates carbonates or oxides and their effect can be accentuated by the presence of suspended muds Some suggestions and limitations follow Calcium sulfate may be introduced in the make up water stream and or produced by the use of sulfuric acid for pH adjustment The concentration of calcium sulfate should be kept below 1000 ppm expressed as CaCO Calcium carbonate generally will not form scale in the cooling tower if carbonate scaling does not occur in the condenser However if make up water contains surplus free carbon dioxide scaling may be inhibited in the
20. g tower mechanical equipment Shipment of these parts is normally made within ten days after an order is received If emergency service is necessary contact the local Marley sales office or representative for assistance To prevent prolonged shutdown periods in case of damage to the mechanical equipment it is suggested that the following parts be carried in the owner s stock One fan assembly One Geareducer assembly One drive shaft assembly One electric motor Six branch arms Six seal rings 100 ft roll of Bandit One box of Band it buckles Be sure to furnish the tower serial number when ordering parts Accessories Marley accessories are designed for improved maintenance access safety component handling and the general customization of the tower to suit your process These accessories include stairways walkways external and internal mechanical equipment removal systems derricks and davits as well as variable frequency drives page 14 and other retrofittable control devices Please discuss your needs with your Marley representative 21 Troubleshooting Trouble Cause Remedy Motor Will Not Start Power not available at motor terminals Check power at starter Correct any bad connections between the control apparatus and the motor Check starter contacts and control circuit Reset overloads close contacts reset tripped switches or replace failed control switches If pow
21. iency of the plant output Although the reduced cold water temperatures that result from maximum fan power utilization are usually beneficial to plant output the amount of fan power affects the cost of running the cooling tower As these variables interact on a cooling tower the operator must find the proper trade off between these opposing forces These instructions will assist in obtaining efficient long life from Marley cooling equipment Direct questions concerning tower operation and maintenance to your Marley sales office or representative Always include your tower serial number when writing for information or ordering parts Look for this number on the nameplate near the tower access AN Caution Before Start up Safety Temporary safety barricades should be placed around any exposed openings in the operating or nonoperating tower safety harnesses should be worn by personnel where appropriate and other safety precautions should be taken in compliance with OSHA regulations and standards Cleaning Clean any nozzles that are clogged Remove any sediment from the cold water basin sump and screens Use a water hose to flush cold water basins If you are restarting or recommissioning a previously used tower see Warning note on page 17 Inspection It is imperative that all operating assemblies be inspected before they are placed in operation The following is a list of components to be checked before starting the tower
22. l ice formation If the tower has two speed motors operate the fan at half speed forward This also reduces the cooling rate and increases the quantity of warm water at the air inlet 11 A Caution A Caution A Caution 12 Freezing Weather Operation Under extended extreme cold conditions it may be necessary to operate the fan in reverse This forces warm air out through the air inlets melting any accumulated ice Reversal may be at either full or half speed however full speed is recommended if adequate heat load is available Reverse operation of the fan should be avoided where possible and should not exceed 15 to 20 minutes Reverse operation of fans for prolonged periods during subfreezing weather can cause severe damage to fans and fan cylinders Ice can accumulate inside fan cylinders at fan blade plane of rotation and fan blade tips will eventually strike this ring of ice damaging the fan blades or cylinder Ice can also accumulate on fan blades and be thrown off damaging fan cylinder or blades Reverse operation of fans with adjacent fans not operating increases probability of icing The low discharge velocity of moist air from fan cylinders in which fans are not in operation can result in moisture laden air being pulled into the adjacent cylinder in which the fan is operating in reverse increasing this ice buildup Therefore fans each side of the one operating in reverse must be operated in forward rotation
23. lating rate 28 F 15 56 C cooling range To maintain 3 concentrations the required blowdown is 1 1 or 011 times 150 000 gpm 9465 L s which is 1650 gpm 104 1L s If tower is operated at 3 concentrations circulating water will contain three times as much dissolved solid as the make up water assuming none of the solids form scale or are otherwise removed from the system The use of corrosion and scale inhibitors is strongly recommended Chemical Treatment In some cases chemical treatment of the circulating water is not required if adequate blowdown is maintained In most cases however chemical treatment is required to prevent scale formation and corrosion Sulfuric acid or one of the polyphosphates is most generally used to control calcium carbonate scale Various proprietary materials containing phosphates or other compounds are available for corrosion control When water treatment chemicals are required the services of reliable water treating companies should be obtained The circulating water pH should be maintained between 7 0 and 8 5 The Langelier index calcium carbonate saturation index has proven to be an effective tool in predicting the aggressiveness of cooling tower water toward concrete The Langelier index relates the methyl orange alkalinity the calcium hardness the total solids the pH value and the temperature of the water From A Caution Water Treatment these values itis possible to calculate the ind
24. ld be started as are needed to produce the desired cold water temperature If the tower is equipped with two speed motors fans may be progressively started at half speed increasing to full speed as necessary to maintain the desired cold water temperature See Temperature Control and Energy Management on pages 13 and 14 A Caution Operation Tower Performance The following is intended to serve as a guideline for the operation of this counterflow mechanical draft cooling tower The owner may use this information to develop preliminary operating procedures As operational experience with the system accumulates more definitive responses to specific conditions will be developed by the owner s operating personnel Keep the tower clean and the water distribution uniform to obtain continued maximum cooling capacity See Caution note on page 15 and Warning note on page 17 Do not allow excessive deposits of scale or algae to build upon the filling or eliminators Keep the nozzles free of debris to assure correct distribution and cooling of water Uniform water distribution over the entire fill plan area is vital to the efficient operation of a film filled cooling tower The capacity of a tower to cool water to a given cold water temperature varies with the wet bulb temperature and the heat load on the tower As the wet bulb temperature drops the cold water temperature also drops However the cold water temperature does not drop as much as
25. low Control Valves Size Nozzles Orifice Diameter Heat Transfer System Fill Drift Eliminators Louvers Use this space to list specific items needing attention 26 Inspection Checklist Condition 1 Good 2 an eye 3 Needs immediate attention Mechanical Equipment Gear Drive Units Comments Manufacturer Model Ratio Oil Level Full Add Immediately Low check again soon Oil Condition Good Contains Water Contains Metal Contains Sludge Oil Used Type Seals Backlash Fan Shaft Endplay Any Unusual Noises No Yes Drive Shafts Manufacturer Material Action Required Fans Manufacturer Diameter Blade Material Fixed Pitch Number of Blades Adjustable Pitch Hub Material Hub Cover Material Blade Assembly Hardware Tip Clearance Vibration Level Fan Cylinder Height Mech Eqpt Support Mat l Oil Fill and Drain Lines Oil Level Sight Glass Vibration Limit Switches Makeup Valves Other Components Motor Manufacturer hp Frame Name Plate Data F L Amps Last Lubrication Date Grease Used Type No No No Any Unusual Noise Any Unusual Vibration Any Unusual Heat Build up RPM Yes Yes Yes Phase SF
26. o minimize the amount of water that is caused to exit the tower by the velocity of the moving airstream Cold Water Collection Basin Water leaving the fill falls into the cold water basin that forms the base of the tower The normal water level in the concrete basin is approximately 12 305 mm below the top of the curb Adjust the make up water supply to maintain approximately this water level Maintain sufficient water depth to prevent cavitation Note Freezing Weather Operation During periods of low ambient air temperatures 35 F to 40 F 2 C to 4 C or below it is advisable to maintain the cold water temperature at or above 70 F 21 C to retard the formation of ice and to assist in its control The methods used in Minimizing Tower Energy Use described on page 13 are those which the operator would use to maintain water temperature at or above 70 F 21 C In combinations of low ambient air temperatures and reduced loads fan speed manipulation may not be sufficient to maintain an acceptable water temperature Even with fans off the natural movement of air through the tower may be enough to continue reducing the water temperature When that happens it will become necessary to open the bypass valve if so equipped and allow total circulation to flow directly into the cold water basin until such time as the basin water inventory rises to a temperature level sufficiently high to preclude frequent changeovers from normal flo
27. oincide reasonably with the recommended operating water level indicated on the Marley project drawings 5 Start the fan s After 30 minutes operating time to permit Geareducer oil to come up to operating temperature check motor load with watt meter or take operating volt and ampere readings and calculate motor horsepower Refer to Marley Fan User Manual for instructions If it is necessary to adjust fan pitch to pull correct contract horsepower measure results when circulating design water rate at design hot water temperature Horsepower will change with air density Lock out all electrical service before entering fan area A Caution Routine Starting Procedure After periods of routine shutdown the following restarting procedure should be followed Start the circulating water pump s Increase the flow of circulating water gradually to design water rate to avoid surges or water hammer which could damage the distribution piping Circulating cold water over a tower in freezing weather will cause ice to form which may cause damage to the fill system Water should be bypassed directly to the cold water basin until the heat load causes its temperature to rise above 70 F 21 C at which time it may be directed over the tower Also towers must not be operated with reduced water rate and or no heat load during freezing weather If a bypass is used Do Not modulate e Start the fan s On multi cell towers only as many fans shou
28. reased clogging problems due to suspended solids and or biological growth if the water is not properly filtered and treated The dissolved ions do not present unusual clogging problems Contributors to the clogging of fill are trash and debris algae slime and scale with the effects of scale often being worsened by the presence of suspended muds All of these can be controlled with some combination of water treatment screening and filtration and it is the owner s responsibility 15 16 Maintenance to institute a program of water treatment and maintenance that will minimize their impact See Water Treatment on pages 18 and 19 Tower Framework Inspect for cracks and spalling and repair if necessary Keep bolts tight in the mechanical equipment supports Maintain a positive Langelier index in your circulating water See Water Treatment on pages 18 and 19 Drive Shaft Check drive shaft alignment and condition of couplings every six months See the Drive Shaft User Manual for correcting misalignment balancing or replacing parts Electric Motor Lubricate and maintain each electric motor in accordance with the manufacturer s instructions If repair work is necessary contact the nearest representative of the motor manufacturer See Warranty Section of Marley User Manual on Electric Motors Fan Inspect fan blade surfaces every six months For detailed maintenance information refer to Marley Fan User Manual G
29. the wet bulb temperature Wet bulb temperature is the temperature indicated by the wet bulb thermometer of a sling or mechanically aspirated psychrometer A tower does not control the heat load For a given heat load the quantity of water circulated determines the cooling range The hot and cold water temperatures increase with higher heat loads Cooling range is the temperature difference between the hot water coming into the cooling tower and the cold water leaving the tower Fan Drive Airis caused to move through the tower by the operation of electric motor driven fans At full speed these fans are designed and pitched to move the amount of air required to accomplish the design thermal performance Proper utilization of these fans provides the operator a means by which to adjust the level of thermal performance to suit the requirements of the load See Temperature Control and Energy Management on pages 13 and 14 If two speed motors are used allow a time delay of a minimum of 20 seconds after de energizing the high speed winding and before energizing the low speed winding Tremendous stresses are placed on driven machinery and motor unless the motor is allowed to slow to low speed rpm or less before the low speed winding is energized When changing fan direction of rotation allow a minimum of two minutes time delay before energizing the fan motor AN Caution 10 Operation Hot Water Distribution System Hot wat
30. uring the operating season Periodic flushing and cleaning should be done at least twice a year Nozzles louvers drift eliminators and easily accessible fill surfaces should be flushed by use of a moderate pressure water nozzle being careful not to cause physical damage A reliable water treatment program should be installed and maintained 17 Note Note 18 Water Treatment Blowdown Blowdown or bleed off is the continuous removal of a portion of the water from the circulating system It is used to prevent dissolved solids from concentrating to the point where they will form scale The amount of blowdown required depends upon the cooling range design hot water temperature minus design cold water temperature and the composition of the make up water water added to the system to compensate for losses by blowdown evaporation and drift The following table shows the amount of blowdown percent of total water flow required to maintain different concentrations with various cooling ranges Number of Concentrations Cooling Range 1 5X 2 0X 2 5X 3 0X 4 0X 5 0X 6 0X 5 F 2 78 C 78 38 25 18 08 06 10 F 5 56 C 1 58 78 51 38 25 18 14 15 F 8 33 C 2 38 t18 78 58 38 28 22 3 18 1 58 1 05 78 51 38 30 25 F 13 89 C 3 98 1 98 182 98 64 48 38 Multipliers are based on drift of 0 02 of the circulating water rate Example 150 000 gpm 9465 L s circu
31. w to bypass flow That temperature level might be 85 F to 90 F 29 C to 32 C but should be determined by operator experimentation Deicing The formation of ice on towers operating in freezing weather cannot be completely prevented but can be acceptably controlled Ice will form on the relatively dry parts of the tower that are in contact with the incoming air Primarily this includes the columns structural framing and fill at the air inlets Ice forming characteristics on any given tower will vary depending on velocity and direction of wind circulating water rate and heat load The Class 800 tower is designed with few structural components in the falling water zone which prevents damage due to falling ice However structural damage can still result from excessive buildup of ice attached to the fill A regularly programmed inspection one walk around the tower per shift during cold weather operation is the best way to determine if ice buildup on the fill is occurring If ice is observed and determined to be acceptable maintain full total design flow over the tower Excessive ice formation may be controlled by regulating air and water flow through the tower by one or more of the following procedures Shutthefan down Thisreducesthe cooling rateto a minimum and increases the quantity of warm water at the air inlet to a maximum Except for extreme cold conditions or extended freezing conditions this procedure will normally contro
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