JET CONDENSERS VS SURFACE CONDENSERS:
Following gives the comparison between the two types of condensers.
1. Contact between steam and cooling water is direct. They form a mixture of condensate and water after heat exchange.
2. Condensate is not fit for reuse as boiler feed water since circulating water contains impurities.
3. Vacuum rarely exceeds 650 mm of mercury.
4. Quantity of cooling water is less.
5. Less maintenance cost.
6. Low manufacturing cost.
7. Requires less floor area.
8. More auxiliary power required.
1. Exhaust steam and cooling water do not come into contact directly. Condensate and circulating water never mix together.
2. Condensate is quite fit for reuse as boiler feed water.
3. Very high vacuum can be created. So higher plant efficiency.
4. Larger quantity of water is required.
5. Maintenance cost is high.
6. High manufacturing cost.
7. Requires large floor area.
8. Less auxiliary power required.
MERITS AND DEMERITS OF JET CONDENSERS AND SURFACE CONDENSERS:
Merits or Advantages of Jet Condensers :
• Intimate and effective mixing of steam and water
• Requires less quantity of circulating water
• Condenser equipment is simple and occupies less space.
• Cost is low
Demerits or disadvantages of Jet Condensers:
• Condensate cannot be reused as boiler feed water.
• Cooling water should be free from impurities if at all the mixture of condensate and water is to be reused for boiler.
• In high level type, 10 to 15 mm (of Hg) vacuum is lost due to leakage of air into the long exhaust pipe.
• In low level type, there is a possibility of engine being flooded in the event of interrupted steam flow or when the condensate extraction pump fails.
• Vacuum rarely exceeds 650 mm of mercury.
• Air pump of high power is required.
Merits or Advantages of Surface Condensers :
• High vacuum can be created and greater plant efficiency
• Cost of water treatment plant is saved as any type of cooling water can be used.
• The condensate can be salvaged and reused as boiler feed water.
• Suitable for high capacity units - specially for marine applications.
Demerits or disadvantages of Surface Condensers:
• Size is more bulky and condenser occupies more space.
• High capital and maintenance cost.