Power Plant Engineering

22 POWER PLANT ENGINEERING

4. There should be no air leakage into the condenser because presence of air destroys the vacuum
   in the condenser and thus reduces the work obtained per kg of steam. If there is leakage of air
   into the condenser air extraction pump should be used to remove air as rapidly as possible.

1.17.2 Jet Condensers

In jet condensers the exhaust steam and cooling water come in direct contact with each other.

The temperature of cooling water and the condensate is same when leaving the condensers.

Elements of the jet condenser are as follows:

1. Nozzles or distributors for the condensing water.


2. Steam inlet.


3. Mixing chambers: They may be (a) parallel flow type (b) counter flow type depending on
   whether the steam and water move in the same direction before condensation or whether the
   flows are opposite.


4. Hot well.
   In jet condensers the condensing water is called injection water.

1.17.3 Types of Jet Condensers

1. Low level jet condensers (Parallel flow type). In this condenser (Fig. 1.13) water is sprayed
   through jets and it mixes with steam. The air is removed at the top by an air pump. In counter flow type
   of condenser the cooling water flows in the downward direction and the steam to be condensed moves
   upward.

Exhaust

Steam Air

Extraction

Cooling Water

Inlet

Condensate

Outlet

Ta i l

Pipe Over

Flow

Hot Well

Cooling Pond

Air Pump

Suction

Injection

Pump

Fig. 1.13 Fig. 1.14

2. High level or Barometric condenser. Fig. 1.14 shows a high-level jet condenser. The con-
   denser shell is placed at a height of 10.33 m (barometric height) above the hot well. As compared to low
   level jet condenser. This condenser does not flood the engine if the water extraction pump fails. A
   separate air pump is used to remove the air.