19-09-2012, 10:59 AM
CONDENSER
condenser.ppt (Size: 2.99 MB / Downloads: 104)
The functions of condensers in steam power plants are to condense the exhaust steam from the steam engine or steam turbine and also to remove air and other non-condensable gases.
Elements of a condenser plant are:
Condenser body.
A supply of cooling water.
Air pump to remove air and uncondensed vapours from the condenser.
Condensate extraction pump.
A pump to circulate the cooling water through the condenser.
A hot well in which the condensed steam is discharged by the condensate extraction pump.
Arrangements for re-cooling the circulating cooling water.
Classification of Jet Condensers
Parallel Flow Type: Here the steam and cooling water enter at the top of the condenser and flow downwards in parallel. The coldest water is thus in contact with hot steam and, therefore, it is less efficient.
Counter Flow Type:
The steam flows upwards through the conden-ser, meeting the cooling water which flows downwards from the top. The air is removed at the top and the condensate and water, separately, at the bottom.
Since the hottest steam is in contact with the hottest cooling water, it is thermodynamically the most efficient, because heat transfer approximates towards reversibility. Also, the cooling of air is most effective and this will reduce the capacity of the air suction pump.
EFFECT OF AIR LEAKAGE
The effects of air leakage into a condenser are:
an increase in the condenser pressure which limits the useful heat drop in the turbine.
a lowering vi the partial pressure of the steam and of 'the saturation temperature along with it. This means that the latent heat increases and therefore, more cooling water is required. Also, the undercooling of the condensate is likely to be more severe. This will result in lower efficiency.
condenser.ppt (Size: 2.99 MB / Downloads: 104)
The functions of condensers in steam power plants are to condense the exhaust steam from the steam engine or steam turbine and also to remove air and other non-condensable gases.
Elements of a condenser plant are:
Condenser body.
A supply of cooling water.
Air pump to remove air and uncondensed vapours from the condenser.
Condensate extraction pump.
A pump to circulate the cooling water through the condenser.
A hot well in which the condensed steam is discharged by the condensate extraction pump.
Arrangements for re-cooling the circulating cooling water.
Classification of Jet Condensers
Parallel Flow Type: Here the steam and cooling water enter at the top of the condenser and flow downwards in parallel. The coldest water is thus in contact with hot steam and, therefore, it is less efficient.
Counter Flow Type:
The steam flows upwards through the conden-ser, meeting the cooling water which flows downwards from the top. The air is removed at the top and the condensate and water, separately, at the bottom.
Since the hottest steam is in contact with the hottest cooling water, it is thermodynamically the most efficient, because heat transfer approximates towards reversibility. Also, the cooling of air is most effective and this will reduce the capacity of the air suction pump.
EFFECT OF AIR LEAKAGE
The effects of air leakage into a condenser are:
an increase in the condenser pressure which limits the useful heat drop in the turbine.
a lowering vi the partial pressure of the steam and of 'the saturation temperature along with it. This means that the latent heat increases and therefore, more cooling water is required. Also, the undercooling of the condensate is likely to be more severe. This will result in lower efficiency.