WATER COOLED CONDENSER1.docx

8/20/2019 WATER COOLED CONDENSER1.docx

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WATER COOLED CONDENSER

INTRODUCTION

Surface condensers: - In surface condensers, the exhaust steam and water do not come into

direct contact. The steam passes over the outer surface of the tubes thorough which a supply

of cooling water is maintained. This type of condenser is useful where water is available in

large quantities it is usually very impure, for example, sea water and river water, but such

impurities have little effect upon its cooling properties. . In this case the purity of the cooling

water does not matter because apart from any leakages which may occur it is never in contact

with the condensate.

CONSTRUCTION DETAIL OF CONDENSER-- 210 MW -UNIT-6STA!E-2T"S-II

The condenser of !" #$ units % to &'(tage-II'T)(-II is a rectangular shell of surface type.

The exhaust steam flow pattern in the condenser is down flow. The circulating water flow is

of double pass type and the lower tubes are in series with the upper tubes. The condenser is

with divided water boxes to have the tube nest in two parts in order to have *"+ operation

during on load leak testing and maintenance. The circulating water system is of closed circuit

type with a cooling tower. The condenser primarily comprises of

1 Condenser su##or$s

2 %o$ &e''

3 Condens(n) c*a+,er

4 Condenser nec

5 End $u,e #'a$es

6 Tu,e nes$

7 Wa$er ,o.es

8 A(r re+o/a' ss$e+

9 S$ea+ du+#(n) de/(ce

The condenser is rated to handle %% t'hr. of exhaust steam at the parameters of

".!" ata and %.!. /


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0ig. /ondenser


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1 Condenser Su##or$s

The condenser is supported on % springs in the two rows 1 x !2 in order to have flexible

connection with the turbine. It is rigidly connected to the base 13ottom half2 of the 4) cylinder of

the turbine. This kind of support for condenser ensures effective dampening of vibration and shock and also gives provision for thermal expansion of the 4) cylinder of the turbine, condenser neck

and condenser itself.

(ince the condenser has been floated over the springs, empty weight of the condenser is taken

by the springs along with partial operating weight. The remaining operating weight is taken

by the turbine foundation. $hile conducting hydraulic test in the shell side of the condenser

water is to be filled up into steam space up to one meter above the top tube row. )rior to

filling water into condenser steam space for testing, 5acking screws provided with springsupport should be used for ensuring water weight being passed on to them, to avoid over

stressing of springs. )rior to putting the system back in operation, condenser must be floated

over springs to avoid excessive upward thrust being passed on to the turbine foundation.

0ig. /ondenser supports

2 %o$-&e'':

The 6ot well is in the lower part of the condenser to form a storage tank for main condensate. It

also collects the drains entering through flash boxes. It is a water reserve in the thermal cycle

along with de-aerator and boiler drum. 6ot well is divided in the middle through a partition. The

purpose is to separate the condensate condensed in each half of the condenser nest for better

identification of tube leaking 7one. /onductivity measurements are to be done in each


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condensate outlet from the hot well to give a warning of any leakage of circulating water into

the condenser.

Two lines from the bottom of the hot well will take the main condensate to the suction of the

condensate extraction pumps. The hot well is provided with level columns having level

glasses, level switches and level transmitters. It is also provided with no8s of drains at its

bottom. 9ormal water level in the hot well is &*"mm and its capacity is designed to be for

minutes of pumping by a /).

Condens(n) C*a+,er

The condensing chamber is a shell where the exhaust steam of turbine comes into contact with

the tube nest and gets condensed. It is floated on spring supports and welded to the condenser

neck and it8s top. The end tube plates secured to the shell provide support for the tube nest.

3 Condenser Nec4

This is the part of the condenser to form an interconnection between the condensing chamber

and 4) turbine. It is designed such that the exhaust steam of turbine reaches the condensing

chamber with a relatively low velocity and very low-pressure drop. The make-up water line

and 4) bypass steam lines 5oin the condenser at the neck.

5 End Tu,e "'a$es

The end tube plates are perforated plates, which separate the water boxes from the condensing

chamber. There are % end tube plates, two on each side of the condenser, to have divided water box

construction. The circulating water tubes have been roller expanded into end tube plates. These tube

plates ensure a perfect sealing so that the purity of the main condensate is not affected. They are also

designed for withstanding against the difference in pressure between the condensing chamber and the

water box. The end tubes are cladded with stainless steel plates on /.$ side for corrosion protection.

6 Tu,e Nes$:

!. The thickness of the tubes should be as small as possible to have high rate of heat

transfer. The tubes are of outer diameter *.% mm and thickness of ".&!! mm.

. !%!; 9os. of tubes are provided in the condensing 7one and !%" 9os. of tubes in air

cooling 7one.


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. #ethod for making tube to end plate expansion 5oint on at both ends of the tube is by

roller expansion.


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circulating water. $ater boxes incorporate hinge arrangement to facilitate the removal of

cover for enabling leak detection, re-tubing and cleaning of tubes etc.,

8 A(r off Tae Ss$e+:

=lthough the condenser is theoretically expected to condense the entire quantity of exhaust

steam, practically a small quantity of steam will remain in the vapour state along with the air

ingresses into the system and non-condensing gases. This uncondensed vapour and the air

will have to be removed by means of e5ectors in order to sustain the vacuum inside the

condenser. The system, which collects the uncondensed vapour and the air from the

condenser, so as to enable e5ection is known as =I> 00 T=? (@(T#.

=s explained earlier, the pattern of exhaust steam flow is ABown 0low8 and the exhaust steam

gets condensed before reaching the bottom. 6ence the air and the uncondensed vapour will

reach the bottom space of the tube nest in each side.

=t the bottom space of the tube nest of each side, a hori7ontal pipe with perforations at its

bottom surface only is provided for collecting the air and the uncondensed vapour. = 7one

called as Aair cooling 7one8 is formed below these pipes. The air and the uncondensed

vapours existing at the bottom space 1above the hot well water level2 gets sucked 1through the

air cooling 7one2 into these hori7ontal pipes are in communication with the e5ectors through

two vertical pipes, there is vacuum inside these pipes.

(ince the air and uncondensed vapour flow over the surfaces of !%" 9os. of circulating

water tubes separately provided in air cooling 7one, the reduction in specific volume of the

air and the uncondensed vapour takes place 1due to temperature reduction2 resulting in

reduction of the volumetric load on the e5ectors.

9 S$ea+ Du+#(n) De/(ce:

Two numbers of (team Bumping devices are provided for the condenser for dumping bypassed steam

1from 4) bypass system2 directly into the condenser during start-up, load throw-off etc., ach device

is provided with an orifice plate which reduces the bypassed steam pressure to approximately

condenser pressure. The pressure of bypassed steam has already been reduced partially due to

throttling in 4) bypass control valve. #oreover, in5ection of main condensate into the bypassed steamis done here to reduce the temperature.


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!""+ steam dumping can be carried out in condenser for a maximum duration of !" minutes,

and within this time, Cnit operation is required to be brought down to "+ and then the Cnit

may be operated continuously.

0ig. (team dumping 1throw-off2 device

2: TEC%NICAL DATA OF 210 MW UNIT 6STA!E -2T"S-IICONDENSER4-

Des()n Fea$ures4

Table 3.9 – Condenser SpecifcationsType Surace type, double pass with

divided water box

construction.Desin c.w. !ow "",#$$ %3&hrDesin cold wate

te%p.

3"$c

Desin bac'

pressure

() %% o * +abs

-o. o tubes #33$ nos.Tube /.D. x

thic'ness,

"#.0 x $.( thic'

Tube %aterial Stainless steel welded1ST2 1 "09 T 3$0

Surace area 3("( 2"

C.4. velocity .53 %&sressure drop C.4.

side

0.5 %wc

C.4. te%p rise $.5$c


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COOLING TOWER


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DESCRI"TION OF NATURAL DRAFT COOLIN! TOWERS OF

STA!E-2 T"S -2NLC; NE././.2. 0rom basin floor, the hot water rises through risers 1>././.2 and the hot water enters the distribution network at !" metre elevation. The hot water from each riser is

distributed with a >./. main distribution duct and a branch >./.duct. 0rom these ducts, the

water is distributed through =./ pipes which are fitted with no77les and sprayers 1)oly


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Crethane2.

2 In$erna' f(''4 The internal fill is of precast pre-stressed concrete splash bar 14aths2. They are

arranged in !; layers. The vertical spacing of layers is "" mm and hori7ontal spacing is !*"

mm to "" mm.

7as(n4 >./. 3asin of the tower has a partition wall for independent operation. The cold water

collected at each half of the basin is led through /.I (creen to a common channel. This

channel takes the cold water to fore bay of circulating water pump house. The basin can be

isolated from the channel by wooden stop logs and intermediate clay filling arrangement.

$ind baffles are provided to avoid a break-through of air during strong wings, the wind

baffles are form the top of the basin to the bottom of the fill. The length of the wind baffle is

equal to the half of the radius from the outer end of basin, due to this arrangement, carryover

of water by wind is reduced.

O#era$(on Da$a4

Table – Coolin Tower SpecifcationsType -atural drat type-o. 0, or each unitConstruction type 6einorce concrete, hyperbolic,

double curvature shell with a bi

bea% at the base supported on

roc'er colu%ns

Total heiht ( %7ase dia%eter (5.9 %Throat dia%eter 0).( %Top dia%eter 09.(( %8low "#,$$$ %3&hr6ane o coolin $c6ecooled water te%p. 3"$c1%bient wet bulb te%p. "($cDesin relative hu%idity #$1pproach. #$c

COOLIN! TOWER SAM"LE "ERFORMANCE CALCULATION4 -


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( So; Range = Circulating water inlet temperature at cooling tower inlet -

Circulating

cooling water at the outlet of cooling tower.

>ange E ti - to

E 1;.! G .!2 F/

E F/

9ow, Approach = Circulating cooling water at the inlet of cooling tower - Wet bulb

temperature

=pproach E ti - twb

E 1;.! - *.*2 F/

E . F/

ii. Effectiveness of cooling tower

Range

= Range + Approach

X 1 !

>

ffectiveness E > H = !"" +

E . H !"" +

E %&. +

iii. Evaporation loss = ."# . 1." . circulating time . $ t i - t o % in m'hr.

E "."";* x !.; x """ x

E ".D% m'hr.

(/ &eat loa' = mass of circulating water . specific heat of water . $ t i - t o %

E """ x !" x ! x 1(p. 6eat of water E ! kcal'kg ?2

E !D; x !" kcal' hr.

(o, !D; x !" kcal'hr of heat is being re5ected into the atmosphere through the cooling

tower.

60


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WATER COOLED CONDENSER1.docx