Sources of Air in the Condenser and the Effects of Air Leakages on Condenser Performance
- Following are the sources of air leakage into the condenser. The air leaks through the joints since the pressure inside the condenser is less than the atmospheric pressure. This can be reduced by proper workmanship while making the joints.
- The feed water contains dissolved air which is liberated in the boiler during steam formation. Therefore, the exhaust steam carries alongwith the liberated air into the condenser.
- Air dissolved with cooling water is carried in case of jet condensers. Since the condensers work at low pressures, the dissolved air is liberated within the condenser. The amount of air present in case of condensers is about 0.05% of the mass of steam.
Following are the effects of presence of air in the condenser on its performance :
- It increases the condenser pressure hence, reduces the expansion work of the turbine per kg of steam.
- Presence of air lowers the partial pressure of steam in the condenser. The reduced pressure of steam has its lower saturation temperature and higher value of enthalpy of vaporisation. Therefore, to condense the steam it would need more amount of cooling water.