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CONDENSER

FACULTY- ER. Ashok Ku. Patra

SEMESTAR- 3RD

SUBLECT- EME

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STEAM CONDENSERS

Condenser is a heat transfer device in which the exhaust steam of a turbine is condensed by means of cooling water at pressure below atmospheric pressure.

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PRINCIPLE OF CONDENSATION

  • In order to attain maximum work, according to Carnot principle, the heat must be supplied at Maximum pressure and temperature and should be rejected at Minimum pressure and temperature.

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ELEMENTS OF CONDENSING PLANT

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COMPARISION

S.No

Jet condensers

1.

Steam and water comes in direct contact.

2.

Condensation is due to mixing of coolant.

3.

Condensate is not fit for use as boiler feed until the treated cooling water is supplied.

4.

It is cheap. Does not affect plant efficiency.

5.

Maintenance cost is low.

6.

Vacuum created is up to 600 mm of Hg.

Surface condensers

Steam and water does not come in direct contact.

Condensation is due to heat transfer by conduction and convection.

Condensate is fit for reuse as boiler feed.

It is costly. Improves the plant efficiency.

Maintenance cost is high.

Vacuum created is up to 730 mm of Hg.

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JET CONDENSERS

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1.(i) LOW LEVEL COUNTER FLOW JET INJECTOR

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1.(ii) LOW LEVEL PARALLEL FLOW JET INJECTOR

  • Exhaust Steam & cooling water both flow in same direction
  • The mixture of condensate, coolant and air are extracted with the help of wet air pump.
  • Vacuum created in the condenser limits up to 600 mm of Hg.

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2. HIGH LEVEL JET CONEDNSER/ BAROMETRIC JET CONDENSER

  • It is also called Barometric jet condenser since it is placed above the atmospheric pressure equivalent to 10.33 m of water pressure.
  • Condensate extraction pump is not required because tail pipe has incorporated in place of it.

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3. EJECTOR JET CONDENSER

  • The cooling water enters the top of the condenser at least under a head of 6m of water pressure with the help of centrifugal pump.
  • This system is simple, reliable and cheap.
  • Disadvantage of mixing of condensate with the coolant.

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SURFACE CONDENSERS

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SINGLE PASS SURFACE CONDENSER

STEAM IN

CONDENSATE OUT

COOLING WATER

COOLING WATER

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DOUBLE PASS SURFACE CONDENSER

STEAM IN

CONDENSATE OUT

COOLING WATER

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DOUBLE PASS SURFACE CONDENSER

  • It consist of air tight cast iron cylindrical shell.
  • If cooling water is impure, condenser tubes are made up of red brass.

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DOWN FLOW SURFACE CONDENSER

  • This condenser employs two separate pumps for the extraction of condensate and the air.
  • Baffles are provided so that the air is cooled to the minimum temperature before it is extracted.
  • The specific volume of cooled air reduces, thereby, reduces the pump capacity to about 50%. Therefore, it also reduces the energy consumption fro running the air pump.

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CENTRAL FLOW SURFACE CONDENSER

  • Air extraction pump is located at the centre of the condenser tubes.
  • Condensate is extracted from the bottom of the condenser with the help of condensate extraction pump.
  • Provides the better contact of steam.

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EVAPORATIVE CONDENSER

  • The exhaust steam is passed through the series of gilled tubes called condenser coils.
  • Thin film of cooling water trickles over these tubes continuously from water nozzles.
  • During the condensation of steam, this thin film of water is evaporated and the remainder water is collected in the water tank.
  • The condensate is extracted with the help of wet air pump.
  • The air passing over the tubes carries the evaporated water in the form of vapour and it is removed with the help of induced draft fan installed at the top.