How Jet Condenser Works?

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.The condensate then cannot be reused as feed water to the boilers.The process of condensation is very fast and efficient in jet condensers, but here cooling water and condensed steam are mixed up. Due to more intimate mixing of steam and cooling water jet condenser requires less quantity of cooling water for the condensation of steam.And also, the jet condensers require less building space and they are simpler in construction and lower in capital cost.In jet condensers the condensing water is called injection water.

The major 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.

And the Jet Condensers are classified into 3 types which are discussed below :-

1. Low level jet condensers (Parallel flow type).

2. High level or Barometric condenser.

3. Ejector Condenser.

1. Low level jet condensers (Parallel flow type):-

In this condenser water is sprayed through jets and it mixes with steam. And both cooling water and exhaust steam enter to the condenser chamber from the top.Heat exhausting takes place during falling of water through the 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 direction.

2. High level or Barometric condenser :-

The condenser 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.Here, the capacity and size of dry air pump is quite small as it has only to deal with air, and uncondensed steam, and it has not to handle with cooling water and condensed steam.

3. Ejector Condenser :-

An ejector condenser require more water than other jet water condenser. The cost is low size is small. It is simple and reliable but only suitable for small power generation unit.In this condenser cold water is discharged under a head of about 5 to 6 m through a series of convergent nozzles. The steam and air enter the condenser through a non-return valve. Mixing with water condenses steam. Pressure energy is partly convert into kinetic energy at the converging cones. In the diverging come the kinetic energy is partly converted into pressure energy and a pressure higher than atmospheric pressure is achieved so as to discharge the condensate to the hot well.