COOLING TOWER
Contents
1. CECE PERCHE ARI BEHE scia mi a a SG 2 012 91 90 GE Range Factor 26 SELECTION GRAPH 202 LCT 564 TEA nanna Tala NICE LED dic cca A SEE LI E i E 210081 TT A E RETE IE I NNO Im 1 E D SERA AI RSA DNAD TA ANE E N 54 mg SM Si Lt a i i FE Jod HHE EEE EEE PARE ARANAN ae ft NOIN SENDA NEE Sil AAA NAN N _ us Bs SENN DG b NANI 4 hy Est isis iin E LESTIE HB E N mageda HH id Range Factor PETRA NANA 20 40 60 80 100 120 140 160 180 200 220 240 260 280 3002. i T a NL ee s LT 2 n yg AAA Mu EEE ERES TEA a I H eer ee e AT tme e eaa e CES UE Heee eA AA Cotes est ae a a ee AA queer d Etta oe eer ATA ED LIE ZEE EE AAA rest EE ILL CD VEL 400008874007 A E EEE EE 80 08 74 AA AAA La ier see ii a HARANE Te dae EPEBSSHEPLE Het EEE LIE SEU esl VL SL OSE WL SL 4 VLSI VL SI 00c V Sl od 5 NOLO OL OSE NOLO OL Bt 082 NOLO 0 Ore ROLO OL 002 NO OL AAA PATH i CITIES Bir OH DEI HE I E ee I rr Eb SEC A
3. APT uc zd 3221 NOS D ia TT COOLING TOWER INDEX Cooling Tower Introduction Models Panoramic The THERMAC Quality Silencers Hydraulic link up Installation rules Cooling Towers Operation Water Treatments Servicing Selection Technical Data Sound Pressure Levels Range Factor Selection diagrams Dimensions i C 12 16 17 18 19 20 21 22 28 COOLING TOWERS series TE TCN DTCN for civil and industrial applications The range of cooling towers for civil and industrial applications produced by THERMAC is one of the most complete existing in the international market The range is based on five different series of products for a total of 49 sizes covering capacities from 22 kW to 4360 kW 18750 to 3750000kcal h bigger capacities can be obtained by a modular combination of several base units which is a standard procedure for industrial application The high number of available sizes allows in every case a precise unit selection at the right cost without compromises for over or under sizing The construction of all THERMAC cooling tower models is at the highest quality level of this industry and features special devices described in the following pages which reduce lifting and transport problems and installation costs The resistance to atmospheric agents which create rust and corrosion particularly in industrial or marine ambient
4. 717477 3 sensibility threshold for noise continuous exposure D 30 GRAPH La i 63 125 250 500 1000 2000 4000 8000 Tab Attenuation Cowls OCTAVE BAND Hz ATTENUATION IN dB 63 125 250 500 1000 2000 4000 Discharge or suction 1 1 6 12 14 16 16 Cowl Tab 1b Sound attenuators THERMAC cooling towers series 12 and 10 DTCN can be supplied with sound attenuator section of 3 different lengths 500 1000 1500 mm Attenuation values are as per table OCTAVE BAND Hz ATTENUATION IN dB LENGTH mm 63 129 250 500 1000 2000 4000 500 2 4 8 12 16 18 13 1000 6 10 17 24 39 36 26 1500 7 13 24 35 39 37 36 Note due to different tower installation situations the values shown in table 1a and 1b must be considered approximate ACOUSTICAL SELECTION SUMMING UP BAND CENTRE FREQUENCY Hz Tower Lp 63 125 250 500 1000 2000 4000 NC 56 As shown on Noise Criteria Attenuation for a 10m 67 66 57 56 56 52 49 Graph distance 6 6 6 6 6 6 Net Lp qB 61 60 51 50 50 46 43 40 As shown on Noise Criteria at a distance of 10m Graph Lp corrisp 40 of 50 45 41 39 37 Necessary attenuation meet NC 40 dB 3 9 6 COOLING TOWER HYDRAULIC LINK UP Some practical indications about correct installation of the water pipes between the cooling tower and the condenser are noted here they refer however
5. a 2118 3 2 5 2 1 5 1 Range factor ae CDU 70 65 60 55 50 45 40 35 30 25 20 15 10 Water flow L h x 1000 10 200 SELECTION GRAPH 12 20 15TA 200 15TA 120 0001 X u 1 MOI OSE OZE OLE 005 062 082 0 2 092 052 Ove 05 022 012 002 061 081 0 1 091 OSL Opi OEL 021 OLL OOL 06 08 OL 09 OS OF 06 Oc OI LAF Te ME AS Ae cA i A A MR E O SOR i DO ii RO SE EE AAA EEE EEE Eee SU 8 AD IA O E A i i BD I VS USA SD A O UGO DA E RO OD A I GR A SS O I SD 77 77 LT T e A ane A aeee AZZ T HEHHEHE HHEH H AAA A HHHH Hee AAA T IO SR I eee A A AAAA AAN ET O EELEEEECPELEPELELLECELECELLELHEI Co UC HI HE HAMA CLEEEEEEEHHEELLEEEEEEELELEEELELEEELELELELL EE 8 9 CT
6. N N N N CO O N N N N O N 2 32 Si N Go N N N Co N Co N Ox Ox N O N N gt gt sex epos o e neos pn s se on om se on pen on om on em rn a on en no va vn pne NI N N N N N N N N N N T N OO N gt O N N N N N N N N vw N 0 N No On Co N N N da No N N N 9 N EN ON N N Co On N lt lt lt lt lt lt lt N No N 92 w N N N N N N N N N lt lt T N N CO IN a 3 N w b environment Temperature C water inlet temperature C At difference between Inlet temperature and outlet temperature IERI EDDIE sa om os n ow o n n m e n s m en em o o m n n am o m m m m e n em nm asa om x n n m o om m m
7. AEEA ea A A HO AUT eee AAA Ee AREAS CHEHEEHEELLEEEEEEEEEEEEELEBEDELELCDZTI 1 7 2 7248742728728 0 472 4 4H HH A AAA A eee aa A PEA Heee SR Sc ee a E I O O I E se A HII ae a AA A TERA TOA O EA AAT RA AZ HE H4 2 2 725 393 H8 43 2 OS ee QUO E OM SD HR 10 acs ora 091161 05 NOL 2 LL _ COE Jo nosa or 8 06 NOIZ p EE GOE LAD dra 081 NOLO OL Ort NOLO OL NEN hoe es a E i E E yy yy Uri FPS POCO MAS csi Ads Ez Sb E ne Pagano 60 SI Ge SE Range factor 25 SELECTION GRAPH 10DTCN 160 10DTCN 400 15TA 160 15 1000 0001 X u 1 024 004 089 099 0 9 029 009 085 099 OFS 026 005 08 097 Ort OBE 096 OZE ODE 082 092 Ore Ode 002 081 091 021 001 08 09 Or Oc na E
8. SILENZIATORE ESTREMIT MENO RUMOROSI RISPETTO ALATI DI PRESA E SCARICO ARIA Were this is not possible it may become necessary to install the cowls or the attenuators also on the air inlet side See fig 3 TERMAC cooling tower sound pressure level are shown in the relative table As it is known the level has an attenuation as a function of the distance following the equation A L p 20109 dB where actual distance from the tower Lit distance at which the sound pressure measurement has been taken For THERMAC cooling towers this distance is 5 mt The noise level is however increased if the tower is installed near a reflecting wall See fig 4 Practically the overall sound level of a tower installed near wall is increased by 6 if the tower is installed in a corner between two walls the overall sound level is increased by 9 dB It is always recommended that the cooling tower be installed on a flat surface without nearby walls Acoustical selection example A 12 TCN 60 cooling tower must be installed at a distance of 10 m from the property limit at which the sound pressure level must be NC 40 see fig oa The tower has a sound level of NC 56 as per table On the graph it is Shown spectrum together with the sound level corresponding to NC 40 Solution First of all it should be calculated the sound attenuation due to the distance as per the formula A Lp 20109 AL p 20109 1
9. LCT 404 LCT 484 LCT 564 49 47 43 49 50 48 44 50 52 50 46 52 Nota bene Sound pressare levels are an average between each octave band acoustic value calculated for a distance of 5m from the tower 2 the N C are referred to N C graph immediatly superior to tower noise graph 3 noise levels depend on tower positioning For special positioning refer to our Offices 4 Sound levels change with the changing of distance from noise source accordino the table below 14 lt ele le i OM 1 1 distanza in mt 2 1 2 3 4 5 10 20 30 40 50 100 RANGE FACTOR 30 C 29 MER CONDDDDODE Ls efe en omen n n n m m n Ls ee ee en en m nm m n on e fefefe pehe pepe ete EN EN EN EN TBU w b environment Temperature 2 Ni ii Te water inlet temperature At difference between Inlet temperature and outlet temperature 425 325 435 288 235 1 90 m m E 295 245 205 E a an na om m om eee on eon m n e rm oe o on o m m n alafen F E DEE E e E RANGE FACTOR iid di At C cd ids N N O
10. side l 2 THERMAC cooling tower selection is based on the Flow Factor method which allows a precise and quick selection To select it is necessary to know ambient wet bulb temperature T b U entering water temeperature Te temperature difference betwen entering and leaving water AT water flow to be cooled The Flow Factor are tabulated for the most frequent conditions For out of standard conditions THERMAC Engineering Dept can supply a computerized selection Selection example Data environment wet bulb temperature 23 e inlet water temperature 35 temperature difference between inlet and outlet water 5 5 C e Water flow to be cooled 100 000 Solution In the Range Factor Table we find the right value for the external wet bulb temperature of 23 C This value is calculated in function of the water difference temperature of 5 5 C and of the water inlet temperature of 35 So we have a Range factor of 2 33 18 Now we can access the graph select the Cooling Tower size and model according the water flow of 100 000 and the Range Factor already computed of 2 33 On the horizontal graph axis we find the water flow while the Range Factor are shown on the vertical one According the two values of 100 000 I h and 2 33 we find on the graph the following tower models 12TCN IODTCN 15TA On the horizo
11. supporting beams for installation on antivibration mounts The THERMAC cooling tower base is strengthened by a series of profiles specifically suitable for installation on antivibration mount without any necessity of supporting bears as is requested for most of the cooling towers available in the market This particular feature reduces the installation times and costs and makes it possible to lift the cooling tower from lugs in the upper part without any danger of yielding or deformation of the bottom part Maximum protection against athmospheric agents and industrial fumes All the Sendzimir galvanized steel panels that make up the cooling tower casing undergo individually an extended THERM O PAINT painting cycle with oven baking After assembling a further painting cycle eliminates the possibilities of paint scratches due to assembly The fan impellers undergo the same painting cycle of all other components Al these features guarantee over 10 years unalterability of the cooling towers in high pollution urban areas while also giving a high resistance in marine athmosphere or in areas with industrial fumes This can be translated in short servicing times and low maintenance costs for the end user and in extended operational life Therm o THERMAC specification for the painting of the cooling towers Primer colour green bonding agento Epoxypolyamidic aspect of dry film semi matte roduct type bicomp
12. 0 5 6 dB The sound attenuation is therefore dB for all frequencies This value can be deducted from the 12 TCN sound pressure level It is now nwcwssary to check the differences of sound level between the attenuated noise and the required NC 40 condition From the table it can be seen that the excess differences are Hz 125 Hz 250 laB Hz 500 5qB Hz 1000 9 Hz 2000 70B Hz 4000 60B Therefore to respect the NC 40 requirement it will be necessary to select a silencer with an attenuation value at least equal for each frequency to the above values From table 1 we select a 500 mm silencer which is largely sufficient It will have to be mounted on the fan section air inlet 10 FIG 3 272222772 2 The same procedure is also applicable for the acoustic cowls In this case the specific cowl attenuation values should be used Note if the protected area had been at a higher level than the tower the same procedure could be applied the result would have been even more favourable for two reasons a a lower sound level at the air outlet b a higher FIG 5a attenuation effect due to the distance as the protected area would only be interested by component of the total acoustic emission due to inclination angle See fig 5b 80 70 TT WA M lly 60 50 RI Ll dedi is WN
13. 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 Water Flow L h x 1000 27 DIMENSIONS mm ATE 15TA 2120 1010 __ 930 7 m 2930 7g Water inlet Up Water outlet Drain 4 5 4TE 7 5 4TE 10 EE 1240 9 2400 A I ua j G Water Inlet up overflow Water Outlet Drain 28 DIMENSIONS mm 12TCN pi 940 2365 Water inlet up Overflow Water outlet Drain 12TCN 40 94 NENNEN A T E G Water Inlet up overflow Water outlet Drain e i 29 DIMENSIONI IN mm Modulo di base 202 282 Modulo di base 303 363 Modulo di base 404 564 30 Water Water Waer make Overflow D LCT 202 DN 200 DN 200 2 33 3 LCT 242 DN 200 DN 200 LCT 282 DN 200 DN 200 2 S LCT 363 2 X DN 200 LCT 404 2 x DN 200 DN 250 LCT 484 2 x DN 200 DN 250 LCT 564 2 x DN 200 DN 250 Note modular configuration has the same single module depth and height and a total length equal to single module length multiplied by the module number I E the 3 363 model has a total length equal to 3x5 48 16 44 m Dimensions are subject to changes without notice Technical drawings will be supplied on order By BI DIEFFE s r l Via Is
14. anks to the reinforced base structure For this same reason it is also possible to lift the cooling tower from lugs in the upper part Series 15 TA cooling towers of this series are particularly suitable for large industrial applications where energy consumption limitation is quiet important The 15 TA towers features aerofoil axial fans directly coupled to totally enclosed motor suitable for operation in high humidity ambient The modular construction of these units makes it possible to assemble together several base modules to form a high capacity heat rejection system The standard construction is based on 15 sizes with capacity from 520 to 4360 kW 450000 3 50000kcal h the 15 TA towers have a particularly sturdy construction to face the heavy duty working conditions A characteristic feature of these towers is that the sheet metal sump tank can be eliminated when an existing tank can be used In this case the air enters the cooling tower through particularly shaped louvers which do not allow water discharge Series TAG The THERMAC range also includes industrial cooling tower of very large size of the TAG series featuring axial fans connected to the electric motor by means of a gear reducer he capacity can reach up to 5MW for each cell with a 4mt diameter fan he towers can be with or without sump tank The structure is in steel profiles hot dip galvanized after fabrication with painted or galvanized panels These to
15. de of rubber for an actual self cleaning action when solid parts pass through them The large nozzles diameter reduces the pump head and consequently the energy consumption The nozzles are mounted over polyvinil or polypropilene spray pipes with a quick release fastening system for ease of inspection or replacement nozzles distribution pipes are fixed by means of O RINGS on a steel header and are therefore easily removable Droplet eliminators Our towers are equipped with specially designed droplet eliminators for vertical air How their four direction changes assure an efficiency up to 9976 Droplet eliminators are made of high quality PVC with special pigment which gives high resistance to environment agents UV ray and inorganic chemical agents droplet eliminators are solidly fastened to the tower structure so they can t be diverted from their lodging by bad weather Moreover they are strong enough to weather the hail storm The fastening system allows an easy disassembling and or substitution Optional e Accessories THERMAC cooling towers can be equipped with several optional and accessories to meet specific installation requirements The main accessories and optional are as follows Special material construction 304 316 Peralluman e Wet deck in special material self extinguishing black PVC high temperature 120 C PVC galvanized steel stainless steel e Double
16. e lower than the ambient wet bulb temperature increased by 2 3 C 16 As is well known the cooling tower selection depends from the heat rejection value and from the ambient wet bulb As far as this is concerned it must be kept in mind that there may be an increase of its value for short periods during the peak season when there is also the peak cooling demand To prevent the risk of overloading the water chillers it is advisable to select the cooling tower for a wet bulb temperature about 2 C higher than the site design one This method beyond preventing overloads will determine a lower water chiller energy consumption during the season For process cooling in the petrochemical industry there can be frequently water temperatures of 65 70 This may require a replacement of the standard wet deck with the special high temperature one In case of doubt consult the Engineering Dept WATER TREATMENT 15 unavoidable in a cooling tower the accumulation of air conditioned impurities and the increase of salt concentration in spite of the bleed off This is a great handicap for any heat exchange process and penalizes the water chiller operation short description of the disadvantages and the possible remedies 1 Scaling and decrease of refrigerating capacity he hydraulic circuit and the condenser pipes are subjected to scaling when the soluted salts and the gases contained in the water reach their solub
17. een sction and discharge Prevent warm air or fumes inlet The tower should be positioned away from warm air exhausts kitchen fumes etc which causes effects worse even than VENTO short cycling If at all possible position the ERRENTE tower near the air conditioning exhaust orienting the expelled air on the fan section The lower wet bulb temperature of the expelled air will increase the cooling ara tower capacity Beware of prevailing winds The prevailing winds increase the short cycling risk between discharge suction air Tend to bend the discharge air in their direction and induce depression zone on the side opposite to the wind direction If the fans are located on this opposite side there will be almost sure short cycle see fig 9 Conversely if the wind blows directly against the fan section it may create instability of air flow inside the tower In these cases the towers should be protected by a wind breaking barrier wich should have a height lower than the tower and should be positioned at a certain distance FIG 9 Respect service clearances necessary service and operation clearances as specified in the installations instructions should be always observed Ducted installation If the tower should operate with ducted air intake or air discharge the motor power and the pulley s drive ratio should be carefully checked to face the duct s pressure drop Fog
18. erature PVC up to 120 C Galvanized steel e Stainless steel 1 is therefore possible also the cooling of water or process liquids at high temperature Pe at RETA Fg P ara FPP dd mr rs STI F ri j ma d ET E he in 1 E 4 er F z an m ie ail eae F f T y fig Sump tank strength and rigidity and corrosion resistance sump tank is assembled with sheet metal panels externally painted with the same method alredy described and zinc chromatized bolts After assembly a special bituminous paint is sprayed over the internal surface to give a maximum protection against the corrosion caused the increasing amount of aggressive parts in the water On the sump tank are mounted the make up water connections with automatic float valve the over flow connection and the drain connection On the water outlet to the installation circuit a metallic filter retains dirt particles or heavier solids On the water inlet pipe a by pass tube with bleed off valve allows a continuous water dilution to keep under 7 control the water salt concentration Low pressure drop water sray nozzles The nozzles have been recently redesigned with large diameter and great water flow allow an extended and Uniform water distribution They are ma
19. erence in example if a correction of the wet bulb temperature down to 0 5 C less and 0 25 C less in the inlet water temperature difference will confirm the 12TCN 100 selection Generally it is possible to find a satistactory compromise In those more binding cases refer to our Technical offices for an aimed selection done with the aid of the computer DATA nominal power water flow air flow 12 100 TODTCN 120 1ODTCN 140 1ODTCN 160 1ODTCN 180 1ODTCN 200 1ODTCN 240 1ODTCN 280 1ODTCN 320 TODTCN 360 1ODTCN 400 Nota bene 1 table capabilities are referred to Water inlet temperature 35 Water out temperature 29 4 c Wet bulb temperature 25 6 c 2 the on board power gives an outlet air flow static pressure of 50 Pa 5 mm c d a 3 waterrate is referred to a spray noozles operatine pressare of 30 kPa 3 m c d 0 3 bar 20 SOUND PRESSURE LEVELS PER OCTAVE BAND 5m dB Mode NC 63 125 250 500 1000 2000 4000 Criteria 5 7 5 10 15 15TA 120 15TA 140 15TA 160 15TA 180 15TA 200 15TA 240 15TA 280 15TA 320 15TA 360 15TA 400 15TA 480 15TA 600 15TA 720 15TA 800 15TA 1000 12TCN 20 12 25 12TCN 30 12TCN 35 12TCN 40 12TCN 45 12TCN 50 12TCN 60 12TCN 70 12TCN 80 12TCN 90 12TCN 100 TODTCN 120 TODTCN 140 TODTCN 160 TODTCN 180 TODTCN 200 TODTCN 240 TODTCN 280 TODTCN 320 TODTCN 360 TODTCN 400 LCT 202 LCT 242 LCT 282 LCT 303 LCT 363
20. esins system to decrease the make up water hardness he problem should be studied on a case by case basis also from the economical point of wiew with the assistance of water treatment specialists Fattore di incrostazione condensatore C Kcal FIG 12 3 Protection against corrosion The addition in the water of chemical substances like chromates phosphates etc generates a protective film on the metal surface of the whole hydraulic circuit which prevents corrosion The chromates are very effective onhibitors for waters in a wide pH range from about 6 5 upwards With these substances it is necessary to keep with precision the minimum required concentration because if it goes below the minimum it can create pitting corrosion On the other hand the chromates are slightly toxic and tend to be eliminated from common use The poliphosphates are not toxic but tend to favour the growth of algae and fungi Periodical water treatments can be made with Sodium silicates or phosphates and silicates mixtures It is however always advisable the assistance of a specialist A Control of algae and fungi growth These microorganisms as said before find a very favourable ambient to their growth in the cooling tower sump tank Their growth must be fought with biocide treatment chlorine or other substances It is advisable to use two different biocides alternatively to avoid that the microorganism develop a resistance or an immunity to the
21. formation In certain ambient air conditions particularly in winter or in certain mid season periods there can be fog formation The probability of fog formation can be checked on the psychrometric graph When the line that joins the ambient air wet bulb with the tower discharge air wet bulb temperature gets outside the saturation curve it is probable that fog formation occurs see fig 10 Check the site temperature and the tower operation cycles If fog formation is probable the tower positioning should not produce obstacles or complaints example near heavy traffic roads residential areas etc PSYCHROMETRIC GRAPH 33 32 31 29 2 28 25 55 LI JE RC Hi ia 84 DEL V LT T SE XA 3 ARI SUT z LENAS E AVIA IE A USAT Am 4 4 LS 25 3 5 Em s Si 7 J gt a 8 N NE 5 M A T Y A MINI Pu LEU y 2 7 3 a NM of bh d 20 a FIG 10 27 Os VOLUME SPECIFICO ARIA SECCA TOWERS FUNCTIONING AND OPERATING Hereafter some pratical informations are given for better cooling tower funct
22. ility limit and precipitate on the tube walls on the heat exchange surfaces etc Scaling not only reduces the useful pipe section but also creates a thermally insulating layer on the heat exchange surfaces which progressively reduces the water chiller capacity Furthermore within the cooling towers there may be a growth of algae and fungi which obstruct the pipes As an example in Tab 2 are shown some typical fouling factors related to the scaling Tubi 0002 0004 0006 0008 thickness in the pipes which demonstrate the pulit Fattore di incrostazione condensatore E decline of the condenser total thermal FIG 11 transmission coefficient and the percentage surface increase which would be necessary to keep the performance at the originary level Fig 11 shows a curve giving the increase in the condensing temperature inside a water cooled condenser as a function of the fouling factor Fig 12 gives also the increase in the compressor power absorption as a function of the condenser fouling factor 2 Protection against scaling In order to reduces the tube scaling in case of high hardness water it is possible to use chemical inhibitors which increase the concentration level determining the salt precipitation particularly Calcium and Magnesium carbonates The most common inhibitors are based on acids non organic phosphates and similar substances Also other methods are however effective like ion exchanging rh
23. ioning and operating 1 Water consumption Generally the cooling towers have a water consumption around 2 4 of the total circulated volume Theorically the evaporation consumption is about 1 for a water temperature difference of 7 C but to this it should be added the water consumption due to the bleed off and the water losses due to the discharge of entrainment 2 Bleed off Bleeding off a certain water quantity is necessary to reduce the salt concentration in the tank and in the circuit and to eliminate the possible impurities which tend to accumulate inside the sump tank The quantity of bleed off water depends from the water hardness the harder the water the bigger the water bleed Off For average hardness water a pratical rule is to have a bleed off quantity equal to the evaporated quantity i e 1 276 In this way the salt and impurities concentration will reach a maximum value equal to twice the original value To obtain a higher precision and to calculate the bleed off flow for various salt concentrations in the water the following formula can be used bleed off flow x Cr Le x where Le water rate evaporated l h kg h It depends from cooling tower capability or better from rejected heat At standard conditions the heat evaporation rate is 540 kcal kg 0 627 kWh kg For example the model 12 TCN 100 at standard conditions rejects 392 000 kcal h 455 8 kW The evaporation rate is 392 000 kcal kca
24. is another strong point in favour of selecting a THERMAC cooling tower The heat exchange efficiency of all models which reaches particularly high values contributes to a sensible limitation of energy and water consumption Several design alternatives and optional accessories are available to match specific installation and operation reqirements for civil and industrial applications THERMAC Engineering Dept has acquired a vast experience in the design of heat exchange equipment with a remarkable field obtained know how caused by the follow up of installations in the most diversified operational conditions Thanks to this experience THERMAC can face any fluid cooling technological problem even if largely outside standard conditions according to Client Designer or Installer requirements with the confidence of finding the right solution in terms of functionality reliability efficiency operation THERMAC cooling towers are designed by means of aCAD system which guarantees an accurate unit dimensioning perfectly matching the operating conditions at a minimum cost WIDE MODEL SELECTION THERMAC cooling towers are divided in five models each of which gives a solution to different application requirements main characteristics of each series are hereinafter summarized Series 4 TE These are small capacity available in 4 sizes from 22 to 65 kW 18750 56000 kcal h suitable for use with package units or small water chille
25. itable for operating in saturated air The shaft is cadmium plated steel and is supported by permanently oiled ball bearings he fans undergo the same painting cycle already described for other components The fans are statically and dynamically balanced balls bearings Both motor and fan bearings are of the permanently oiled type On all these models the fan section is protected by a galvanized and painted steel mesh to prevent accidents and collision with solid objects COWLS AND ATTENUATORS FOR NOISE CONTROL The series 12 and 10 DTCN cooling towers can be equipped with two different systems for noise control PROTEGGERE attenuation and deviation cowls with acoustic barrier effect They can be installed on the air inlet or outlet in order to the noise direct propagation towards neighbouring zones These cowls are manufactured in Sendzimir galvanized steel sheet with internal glass fibre sound absorbing mat protected by a perforated metal sheet The complete cowl is painted with the same system described for other components The inlet or outlet air is deviated by the cowls and also the noise is deviated and partially attenuated and does not hit directly the protected areas EVENTUALE SILENZIATORE cowl sound attenuation is definitely inferior to that achieved by proper sound attenuators but also their cost is sensibly lower In many cases the cowls are sufficient and can be conveniently
26. l _ _ 455 8 KW KW h _ kg a 540 h ff kg 0 627 kg ET Cr make up water salt concentration ppm Ca recirculated water Maximum allowable salt concentration ppm TH20 C 20 237 30 39 40 45 50 60 70 Ca p p m 230 240 225 200 175 150 125 110 100 Tabella per determinare il COEFFICIENTE DI BLEED OFF Durezza massima ammissibile Ca Durezza acqua di reintegro Cr p p m T C 20 25 30 39 40 45 50 Ca p p m 280 240 225 200 175 150 125 110 0 45 0 5 0 6 0 75 0 7 0 8 1 1 33 151 1525 1 66 2 5 1 66 2 3 6 2 7 9 9 5 8 Procedine with the example of 12TCN100 model for wich the rate was Le 726 kg h with make up water hardness of 15 F 150 p p m and water inlet temperature of 35 from the herewith table we find a coefficient 3 water bleed off should be 3x 726 2 178 kg h l h The water consumption wiil be 2 178 726 2 904 kg h Using partially softned water to 7 5 75 p p m we will have 0 6 x Ls 0 6 x 726 436 kg h the total consumption should be 436 726 1 162 kg h 3 conditions cooling towers for confort air conditioning uses are normally selected for standard water temperatures conventionally it is accepted an entering water of 35 and a leaving water of 29 5 C The temperature difference 15 therefore fixed in 5 5 C In any case the minimum leaving water temperature cannot b
27. ntal axis we find the water flow value of 100 000 and going the top vertically crossing with the Range Factor Value of 2 33 we find that the crossing point is near to the half curve for the 12TCN 100 120 15TA 120 models Presuming we need a centrifugal fan model we should discharge the 15TA 120 model Then we can cut our selection between the 12TCN 100 and the 120 models On principle in this kind of circumstaces we have to choose the bigger size IODTCN 120 model the exemple But there is a sensitive difference in cost between the two models because the models have fans on each side whereas the 12TCN models have single side fans It could be useful in this case to review the project data and verify if it is possible to fall within the smaller size We have the following option to check 1 Wet bulb air temperature How was it setted Is it possible a reduction down to 1 C from the initial value In thi case the Range Factor will increase to 2 55 so the previews crossing point would fall nearly to the 12TCN 100 graph 2 Water temperature difference Is it possible reduce the temperature gap to 5 C instead of 5 5 C If it is the Range Factor increases to 2 62 and the selection would cross exactly the 12TCN 100 graph 3 If the entire corrections are not possible verify if it is possible at least a partial correction of both wet bulb temperature and water inlet temperature diff
28. ola della Scala 34 A 37068 Vigasio VR Tel 0456685453 Fax 0456698581 www thermac it info thermac it
29. onent catalyst catalysis ratio 100 p paint 25 p catalyst Finish colour aluminium bonding agent acrylic aspect of dry film bright product type bicomponent catalyst catalysis ratio 100 p paint 50 p catalyst Painting cycle cold zinc on weldings and edges cleaning and degreasing with solvent application of prime coat with catalist 2576 drying time 6 hours minimum application of intermediate coat with catalyst 9 5076 application of finish coat with catalyst 50 drying time 48 hours minimum This specification refers to all the towers subjected to painting motors and drives excluded The finish is applied on the external walls only Wide surface wet deck he wet deck is formed by a cellular PVC structure with wide contact surface to enable an efficient and uniform distribution of the water droplets sprayed by the nozzles The water ways in the wet deck are downward inclined in such a way to maximize the heat exchange surface between air and water inclination angle also opposes water carry over outside the wet deck The above feature optimize the heat exchange efficiency and contributes greatly to limit the water consumption The standard wet deck is in rigid PVC stabilized to UV radiation with maximum operation temperature of 80 C Upon request the wet deck can be supplied in one of the following materials Self extinguish black PVC class 1 High temp
30. previous 12 TCN series The units have a double centrifugal fan section placed on opposed sides in a semi enclosed position The range of capacities is from 520 to 1750 kW 450000 to 1500000 kcal h divided over 10 different sizes They can be used in relatively large civil installation in refrigeration plants and generallt in process fluid cooling It is possible to duct the air inlet and outlet to install sound attenuators on the suction or discharge side to reduce the noise level Also these cooling towers can be positioned on antivibration mounts tithout the necessity of supporting beams thanks to the reinforced base structure For this reason it is also possible to lift the cooling tower from lugs in the upper part without yielding of the bottom The units can be decomposed in a modular way to facilitate freight and site positioning These are modular units of large capacity for civil or industrial application They feature internally placed centrifugal fans not protruding from the tower cabinet capacity range of the standard units covers from 890 to 2500 kW 765000 to 2150000kcal h divided over 8 sizes However assembling together several base modules it is possible to reach much higher capacities up to more than 400 kW 6380000 kcal h he unit construction is particularly sturdy and heavy duty The cooling tower can be positioned on antivibration mounts without the necessity of supporting beams th
31. pump supply head and the pump suction head For a given cooling tower size the geodetic head remains constant indipendently from the type of circuitation and can be seen in fig 6 Prevalenza geodetica Frevalenza geodetica Battente sull aspirazione Battente sulla mandata Pompa Batiente sull aspirazione Condensatore FIG 6 Reintegro a galleggiante Lx Reintegro a galleggiante FIG 7 External accumulation water tank An external water tank should be used except for very special cases whenever the tower operation continues during the winter period and the tower is installed outdoor water tank can also be installed inside building in order to avoid ice formation during off operationperiods As a further caution the water tank can be equipped with thermostat controlled electric heaters possible example of the curcuit is shown in fig 7 accumulation water tank 15 not necessary when the tower is in operation only during summer time As a caution howerver it can be installed an electric heater with manual or automatic control to protect against sudden temperature drops in mid season A typical example is shown in fig 8 Multiple users In case of multiple users with variable water due either to regulation or intermittence is now necessaryto employ an intermediate tank subdivided in two parts COLD WATER TANK SECTION AND WARM WATER TANK SECTION The
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33. re will be a warm water tank section to tower circuit with strictly constant water flow and a cold water water tank section user circuit with variable waterflow It is necessary that the warm water to tower circuit pumps and or the water fan can be controled from thermostat sensing the water temperature in cold water tank section In case of multiple users to avoid employing the intermediate tank it is appropriate to have a regulation by means of deviating 3 way valves in order to have a constant water to the tower It must be emphatize that the water flow throught the cooling tower must be constant and possibly without intermittence he tower flow constance is necessary for regular water duller operation and it limits the internal corrosion caused by the wet dry effect in the sump tank walls Cooling towers in parallel In case of use of several towers in parallel it is necessary to use an intermediate tank This can be eliminated if the cooling tower sump tanks are connected by equalizing pipes in order to keepan equal water level in the various towers see fig 8 bis FIG 8 bis EQUALIZING PIPE COOLING TOWER INSTALLATION Very often the reason for a defective tower operation can be found in a improper installation The main rules follow are 1 14 Prevent air short cycling Position the tower on a flat surface away walls roofings that may determinate air short cycles betw
34. rs They feature an axial fan very simple yet sturdy construction great operational reliability and an interesting cost The low noise level and the reduced water consumption make it possible to install these units even in urban areas with high population density Series 12 TCN These towers features centrifugal fans mounted on one side only in semi enclosed position protected from rain snow hail They cover an intermediate capacity range from 87 to 436 kW 75000 to 3 5000 kcal h which is most frequently used for standard civil and commercial airconditioning installations The units are available in 12 sizes with capacity increments about 10 between two consecutives sizes to allow an exact selection at the lowest cost The series 12 TCN cooling tower can be ducted on the suction inlet and discharge outlet for internal installation they can be equipped with sound attenuators see the followiong pages to reduce the sound level The position of the fans on one side only allows placement against a wall These units are designed for assembly on antivibration mounts without the necessity of supporting beams as it is common to most of the other cooling towers in the market thanks to the reinforced base structure This greatly reduces installation costs cooling tower can be normally lifted from lugs in the upper part without yielding of the bottom Series 10 This cooling tower series is the continuation of the
35. same agent COOLING TOWER SERVICING For a regular plant operation a service schedule should be set We refer to each equipment service manual for specific operation However hereinafter are listed the main checks that should be carried out on a cooling tower Air side 1 check belt tension and belt wear in units with centrifugal fans Check that the impeller is centred on the shaft and is rigidly fixed without rubbing against the scroll Check the state of fan of fan and motor bearings and the state of lUblification check the dampe if any on the fan discharge check electric motors and the relative circuits check the state of the moisture eliminators removing any obstruction check the state of the wet deck Control its integrity and that it is not obstructed by dirt or by solid particles ge gt clean the sump tank least once a month clean also the filter on the water outlet control nozzle cleanliness at seasonal start up Periodically check that the pressure at the nozzles is as per service manual indications check the bleed off and control its correct operation at the supplier s instructions check the water softener operation if any according to supplier s instructions Use according to necessity the biocides to eliminate algae and fungi verify the cooling tower structure to note rust or corrosion In that case remove rust or corrosion stains restoring with the indicated paints the protective layer Water
36. speed fan motors 4 6 or 4 8 poles to control tower capacity e Centrifugal fan outlet damper actuated by outside temperature to control tower capacity e Antifreeze sump tank electric heaters with or without thermostat e Noise attenuation cowls for installation on air inlet or outlet Within certain limits the tower noise can be attenuated by these cowls at the lower cost than attenuators see next item Sound attenuators for installation on air or outlet available in length of mm 500 1000 or 1500 see description in the next pages Bigger fan motors available only 12 an 10 DTCN to achieve fan static pressure up to 80 8 mm w g for ducting or sound attenuators installation Antifume coils to prevent fog formation see description in the next pages Efficient fans with low noise level Mod 12TCN 10DTCN LCT The fans mounted on these cooling tower series are of the DWDI centrifugal type forward curved selected for a tolerably low noise level The fan drive is by means of pulley and trapezoidal section belts The motor is of the TEFC type suitable for high moisture ambient and it is mounted on an adjustable skid placed inside the fan section for a better protection against rain and snow he motor shaft is cadmium plated is supported by Mod ATE 15TA These towers are equipped with aerofoil axial fan in light alloy directly coupled to the electric motor The motor is watertight su
37. to the most common cases 1 12 Pump location The circulating pump must be positioned below the tower sump tank It must have a suction head of at least 30 cm in order to offer a reasonable safety margin against pump cavitation with air in the circuit and consequent unproper operation of the whole installation which may cause severe damage on the refrigeration compressor Two examples are given in fig 6 in which the pump suction heads are quite different although the level difference between tower and condenser is identical Preference should be given to the solution with higher head Sump tank to pump suction line dimensioning It is advisable to select the sump tank to pump pipe diameter in such a way to minimize the pressure drop A good rule is to select one size up from the calculated diameter in fact it must be remembered that the pressure drop on the section of the pipe will increase in the time due to filter clogging and pipe scaling Hydraulic circuit total pressure drop calculation The hydraulic circuit total pressure drop is given by the sum of the following components pipework pressure drop condenser pressure drop tower nozzles pressure drop pump geodetic head It s a good rule to increase the total so obtained by a good 205 to allow for the pipe section restriction due to scaling the filter clogging etc constance of the pump geodetic head the geodetic head is formed by the difference by the
38. used Attenuation values are reported Table 1 LATO d biis T sound attenuators of different length 500 1000 1500 mm with 12 TCN RUMOROSO i i different noise attenuation capacity See Tab lb The attenuators can be mounted in various positions on the air inlet on the air outlet FIG 2 or on both according to the noise reduction requirements and the site characteristics Generally speaking the fan section side produces a higher noise level than any other side included the upper air outlet The lower noise side is that closed and opposite to the fan section mod 12 the difference can be 6 8 dB for low frequencies and even more the 12 for higher frequencies Therefore when designing an installation a proper tower orientation can reduce sensibly the noise emission towards the protected areas PUNTI DA PROTEGGERE After the fan section the noise part is the upper section Therefore if the cooling tower is installed at ground level and near a multistore building it may become necessary to protect the upper floors the outlet air noise by installing a cowl or a sound attenuator on the air outlet If the tower is a 12 TCN model with a single fan section the lower floors can be protected by orientating the fan section side in the opposite direction See fig 1 If the tower is a 10 DTCN model it should be positioned with the short side towards the building See fig 2 EVENTUALE
39. wers are custom designed follow the particular customer requrement THE THERMAC QUALITY Advantages for contractors designers end users THERMAC production is at the highest industry standard It is choice to which considerable human an financial effort has been dedicated in order to obtain a product capable of obtaining without compromises the preferences of contractors designer and end users The main constructional installation and operation features common to all cooling towers models are hereafter described Great sturdiness and resistence to atmospheric agents The standard construction is in Sendzimir galvanized steel The thickness is variable in accordance with the cooling tower size in order to ensure in any condition the maximum constructional strength and structural rigidity The panels are assembled by means of zinc chromatized bolts with the interposition of high elasticity mastics to guarantee a good sealing even after years of operation The bigger sizes are manufactured in separate sections for ease of transport and site positioning Large size panels or manholes according to model sizes allow an internal inspections or services All cooling tower models upon request can be manufactured in special materials AISI 304 AISI 316 and peralluman Also the wet deck are available in different materials for particular operating conditions see Optionals and Accessories No necessity of
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