Condenser Performance Analysis and Its Improvement

8/11/2019 Condenser Performance Analysis and Its Improvement

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By:

Devendra Khare

Ashish Kumar

Sachin Pal

Anupam Singh


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What is condensate The steam after condensing in the condenserknown as condensate, is extracted out of thecondenser hot well by condensate pump and takento the deaerator through ejectors, gland steamcooler and series of LP heaters. Steam from last stage of LPT Exhausts on

condenser tubecondensation of steam takes placeWater collected in hot well


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Shell of the Condenser The shell is the outer most body of the condenser shell is fabricated from fairly thick carbon steel plates.

Due to its large size the shell is sufficientlystrengthened or stiffened internally with carbon steelplates to give sufficient rigidity for the shell proper.The shell also gives support to number ofintermediate support plates for the long tubes,

depending on the size of the condenser. At the same time the intermediate tube support platesallow for the free movements of tubes in all directionsparticularly lengthwise due to expansion andcontraction occurring during operation.
http://en.wikipedia.org/wiki/Carbon_steelhttp://en.wikipedia.org/wiki/Expansionhttp://en.wikipedia.org/wiki/Contractionhttp://en.wikipedia.org/wiki/Contractionhttp://en.wikipedia.org/wiki/Expansionhttp://en.wikipedia.org/wiki/Carbon_steelhttp://en.wikipedia.org/wiki/Carbon_steelhttp://en.wikipedia.org/wiki/Carbon_steel


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The whole condenser is supported on heavy springs ,mounted on steel sole plates at suitable places on theconcrete foundation At the bottom of the shell where the condensate isallowed to collect, a sump (often referred to as the

hotwell) is provided.This sump is common to both the halves butseparated by a partition wall in the middle up to theheight of the bottom row of tubes.The inside of shell and outside the tubes as a wholeremains under vacuum under normal operatingconditions. Inside the tubes the cooling or circulating water passes through.
http://en.wikipedia.org/wiki/Spring_(device)http://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Spring_(device)


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Air Zone Inside the shell, a central or side portionlongitudinally is separated by an outer shield exceptat the bottom. This partition is called the Air zone.

All the gases released in the condenser due to coolingare taken out via these air zone tubes.From a suitable portion of this air zone inside theshell an air vent pipe is taken out and brought out ofthe shell for connection to an air extraction device.
http://en.wikipedia.org/wiki/Extractionhttp://en.wikipedia.org/wiki/Extraction


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Tube Sheets At each end of the shell, tube sheet of sufficientthickness is provided, with holes for the tubes to beinserted and rolled.To take care of length wise expansion of tubes somedesigns have expansion joint between the shell andthe tube sheet allowing the latter to movelongitudinally.
http://en.wikipedia.org/wiki/Tubehttp://en.wikipedia.org/wiki/Tubehttp://en.wikipedia.org/wiki/Expansionhttp://en.wikipedia.org/wiki/Butterfly_valvehttp://en.wikipedia.org/wiki/Butterfly_valvehttp://en.wikipedia.org/wiki/Expansionhttp://en.wikipedia.org/wiki/Tubehttp://en.wikipedia.org/wiki/Tube


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Water Boxes The tube sheet at each end with tube ends rolled, foreach half condenser is enclosed in a fabricated boxknown as water box.

These water boxes on inlet side will also have big sizeflanged connections for cooling water inlet at lowerlevel for butterfly valves . small vent pipe with hand valve for air venting athigher level, and hand operated drain valve at bottomto drain the water box for maintenance.Similarly thermometer pockets are located at inletand outlet pipes for local measurements cooling watertemperature .
http://en.wikipedia.org/wiki/Valvehttp://en.wikipedia.org/wiki/Thermometerhttp://en.wikipedia.org/wiki/Brasshttp://en.wikipedia.org/wiki/Cupro_nickelhttp://en.wikipedia.org/wiki/Cupro_nickelhttp://en.wikipedia.org/wiki/Brasshttp://en.wikipedia.org/wiki/Thermometerhttp://en.wikipedia.org/wiki/Valvehttp://en.wikipedia.org/wiki/Valvehttp://en.wikipedia.org/wiki/Valve


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Tubes Generally the tubes are made of brass , aluminumbrass, cupro nickel , stainless steel or titanium depending on the cooling water chemistry.

The lengths are fixed at about -10 mtr for the 200 MWunit, depending on the size of the condenser.The outer diameter is 30 and inner dia 28 mm for easeof handling and ease of insertion through the shelltube holes and for rolling at both ends.
http://en.wikipedia.org/wiki/Stainless_steelhttp://en.wikipedia.org/wiki/Titaniumhttp://upload.wikimedia.org/wikipedia/en/2/25/Dores-Cond-diag1.pnghttp://localhost/var/www/apps/conversion/Documents%20and%20Settings/Siva/Desktop/2BE3%20how%20it%20works.swfhttp://localhost/var/www/apps/conversion/Documents%20and%20Settings/Siva/Desktop/2BE3%20how%20it%20works.swfhttp://upload.wikimedia.org/wikipedia/en/2/25/Dores-Cond-diag1.pnghttp://upload.wikimedia.org/wikipedia/en/2/25/Dores-Cond-diag1.pnghttp://upload.wikimedia.org/wikipedia/en/2/25/Dores-Cond-diag1.pnghttp://en.wikipedia.org/wiki/Titaniumhttp://en.wikipedia.org/wiki/Titaniumhttp://en.wikipedia.org/wiki/Titaniumhttp://en.wikipedia.org/wiki/Stainless_steel


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PERFORMANCE OF CONDENSER About 50 % heat is lost in condenserFor a 200 MW unit 28000 t / hr of CW water is

requiredSlight deterioration in the performance of condenserleads to huge financial lossNormally design value of condenser pressure is 70 mm

Hg abs (0.1 Kg abs)


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10 MM HG IMPROVEMENT IN

CONDENSER VACUUMLEADS TO20 Kcal/kwh (1%)

IMPROVEMENT IN HEAT RATE FOR A

210 MW UNIT AND AN ESTIMATED

COAL SAVING WORTH OFRs 1.2 CRORE PER YEARFOR A RAIL FED STATION


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Pressure v/s Specific Volume

0

2

4

6

8

10

1214

16

18

20

0 1 2 3 4 5

Volume, m3/Kg

P r e s s u r e

, b a r a b s

.


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TWO-PASS SURFACE CONDENSER


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17 September 2014 13

THERMAL PROCESSES OCCURRING IN CONDENSERS

The condenser never receives pure steam from theturbine. A mixture of steam and non-condensable gases (Air-steam mixture) enters the condenser.The ratio of the quantity of gas that enters thecondenser to the quantity of steam is called the relativeair content.

The value of e, depends on type, capacity, load anddesign dimensions of the condenser plant.

sc,m

air m


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17 September 2014 14

FACTORS AFFECTING THE PERFORMANCE OF THE

CONDENSER

CW inlet temperatureCW flowPresence of non-condensable gasesEjector / vacuum pump performanceDirty tubes


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Technical specifications: [210 MW

GGSSTP ROPAR]1. Design C.W. temp.C : 362. C.W. temp. rise C : 8.33

3. Condenser back pr. Mm.Hg abs. : 89.04. C.W. flow quantity,m/hr : 285005. C.W. Side pr. Drop MWC : 3.46. No. of C.W. pass : Two


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7. No. of tubes:

a) Condensing zone : 17234 b) Air cooling zone : 1974 8. Tube dimensions

Tube OD thickness mm :

25.41.245 Length of tube for ordering : 6.49. Tube material

a) Condensing zone : Al-brass

b) Air cooling zone : 90-10 Cu-Ni 10. % tube thinning : 7% 11. water box design pr. : 3.0 kg/cm2g 12. water box hydraulic test pr. : 4.5 kg/cm2g


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Condenser LMTD =TTDactualCond.

rangecoolingCondenser In

)TempI/LCW-Temp.O/LCW(

11.0226.12

)19.98-08.35(

In

= 17.49

26.1210015.10

Condenser efficiency =rangeCooling

100riseCW

= 57.81 %


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Condenser loss due to Fouling:

The performance of a steam surface condenser is negatively affected by tube .Forthe Treated Boiler Feed Water fluid type fouling factor is lies between 7 - 8 s-cm2 - 0C/cal.

Taken , Fouling factor, R f = 7 s-cm2-0C/cal= 19.39 hr-m2-0C/kcal

Effective Condenser Heat transfer coefficient in the absence of fouling calculated as above,

Uclean = 279.61 Kcal/hr/m 2-CThe fouling factor is given as:

Percentage loss in heat transfer rate due to fouling = [(279.61265.23)/279.61]100

= 5.14 %


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Condenser performance analysis on exergy

basis: Generally, the performance of thermal power plants is

evaluated through energetic performance criteria based onfirst law of thermodynamics, including electrical powerand thermal efficiency.In recent decades, the exergetic performance based on thesecond law of thermodynamics has found as useful methodin the design, evaluation, optimization and improvement

of thermal power plants. The exergetic performanceanalysis can not only determine magnitudes, location andcauses of irreversibilities in the plants, but also providesmore meaningful assessment of plant individualcomponents efficiency.


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The irreversibility = energy loss,

Condenser efficiency= 1 ( Idestroyed / m 1 (h 1-h 2))m1= mass flow rate of steam at inleth1= enthalpy at inleth2 = enthalpy at outlet

Qk = heat transfer at temp. T k.

Idestroyed = To*Sgen = { [m1(h1-h2 -To m1(s1-s2) } 1-To / Tk Qk

Condenser efficiency: = 1 ( Idestroyed / m 1 (h1-h2))= 1 (78649.44/(186.1*(2580-167.5)))

= 1 - 0.1751= 0.8249100%= 82.49 %


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Concluding Remarks

The role of efficiency and performance monitoring lies inthe maximizing generation from the Thermal Power Plant.In order to keep maximum output from a given input, theunits must run at maximum possible efficiency. The chief

factor in good condenser performance is the maintenance ofthe most efficient value of back pressure possible withavailable cooling water conditions.Therefore it is important to the efficient operation of a unitthat its back pressure is always maintained at the optimumlevel. It is important that the condenser performancechecked be performed routinely to optimize condensercleaning schedule for achieving best possible heat rate


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By controlling the critical parameters which are mentioned the performance of the condenser can be increased, this is only possible when various plant auxiliaries are performingsatisfactorily

Thus in order to maximize the generation with low generation cost the monitoring of performance of plant isessential.


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THANK YOU!

Condenser Performance Analysis and Its Improvement

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