Power Plant Engineering

FUNDAMENTAL OF POWER PLANT 21

Steam and

Air

Condensate

Tu b e s

Air

Steam

Air

Condensate

Make up

Circulating Water

Water Pump

Fig. 1.11 Fig. 1.12

ADVANTAGES AND DISADVANTAGES OF A SURFACE CONDENSER

The various advantages of a surface condenser are as follows:

1. The condensate can be used as boiler feed water.


2. Cooling water of even poor quality can be used because the cooling water does not come in
   direct contact with steam.


3. High vacuum (about 73.5 cm of Hg) can be obtained in the surface condenser. This increases
   the thermal efficiency of the plant.
   The various disadvantages of' the surface condenser are as follows:


4. The capital cost is more.


5. The maintenance cost and running cost of this condenser is high.


6. It is bulky and requires more space.

REQUIREMENTS OF A MODERN SURFACE CONDENSER

The requirements of ideal surface condenser used for power plants are as follows:

1. The steam entering the condenser should be evenly distributed over the whole cooling sur-
   face of the condenser vessel with minimum pressure loss.


2. The amount of cooling water being circulated in the condenser should be so regulated that the
   temperature of cooling water leaving the condenser is equivalent to saturation temperature of
   steam corresponding to steam pressure in the condenser.
   This will help in preventing under cooling of condensate.


3. The deposition of dirt on the outer surface of tubes should be prevented.
   Passing the cooling water through the tubes and allowing the steam to flow over the tubes achieve
   this.