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Steam Condensers

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Presentation on types of Steam Condensers.

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Steam Condensers

  1. 1. STEAM CONDENSERS
  2. 2. Definition  Condenser is a device in which steam is condensed to water at a pressure less than atmosphere.  Condensation can be done by removing heat from exhaust steam using circulating cooling water  A condenser is basically steam to water exchanger in which heat from exhaust steam is transferred to circulating cooling water
  3. 3. Function  To reduce the turbine exhaust pressure so as to increase the specific output and hence increase the plant efficiency and decrease the specific steam consumption.  To condense the exhaust steam from the turbine and reuse it as pure feed water in the boiler. Thus only make up water is required to compensate loss of water
  4. 4. Advantages of condensers in steam power plant 1) High pressure ratio provides larger enthalpy drop 2) Work output per kg of steam increases and hence specific steam consumption decreases 3) Condensate can be reused as hot feed water to the boiler. This reduces the time of evaporation and hence fuel economy 4) No feed water treatment is required and hence reduces the cost of the plant 5) The formation of deposits in the boiler surface can be prevented with the use of condensate instead of feed water from outer sources
  5. 5. Elements of steam condensing plant 1) Condenser 2) Air extraction pump 3) Condensate extraction pump 4) Circulating cooling water pump 5) Hot well 6) Cooling tower 7) Make up water pump 8) Boiler feed pump
  6. 6. Elements of steam condensing plant
  7. 7. Classification of condensers 1) Jet condensers (or) mixing type a) Parallel flow type (Low level) b)Counter flow type (High & Low levels) c) Ejector type 2) Surface condensers (or) non-mixing type a)Down flow type b) Central flow type c) Inverted type d) Regenerative type e) Evaporation type
  8. 8. Jet Condenser Vs Surface Condenser Jet Condensers (Direct Contact type/Mixed type) Surface Condensers (Indirect Contact type/Non-Mixed type)
  9. 9. Comparison of jet & surface condensers Jet Condensers Surface Condensers 1) Cooling water and steam are mixed up 2) Low manufacturing cost 3) Requires small floor space 4) The condensate cannot be used as feed water to boiler unless it is free from impurities 5) More power is required for air pump 6) Less power is required for water pump 7) Requires less quantity of cooling water 8) The condensing plant is simple 9) Less suitable for high capacity plants due to low vacuum efficiency 10)Lower upkeep 1) Cooling water & steam aren’t mixed up 2) High manufacturing cost 3) Requires large floor space 4) The condensate can be used as feed water to boiler as it is not mixed with cooling water 5) Less power is required for air pump 6) More power is required for water pump 7) Requires large quantity of cooling water 8) The condensing plant is complicated 9) More suitable for high capacity plants as vacuum efficiency is high 10)Higher upkeep
  10. 10. Jet condensers  Jet condensers are used in small capacity units where clean fresh water is available in plenty.  In jet condensers, water is in direct contact with exhaust steam. Hence these are also called direct contact type (or) mixed type
  11. 11. Advantages & disadvantages of Jet condensers Advantages 1) As a result of effective mixing, it requires less circulating cooling water 2) Equipment is simple and occupy less space 3) Maintenance is cheap Disadvantages 1) Not suitable for higher capacities 2) Condensate cannot be used as feed water to boiler 3) Air leakages are more 4) Requires larger air pump 5) Less vacuum is maintained
  12. 12. Surface condensers  Surface condensers are used in large capacity plants  In surface condensers, exhaust steam and water do not mix together. Hence they are also called indirect contact type (or) non-mixed type
  13. 13. Advantages & disadvantages of surface condensers Advantages 1) Can be used for large capacity plants 2) High vacuum can be created 3) Condensate is free from impurities and can be reused as feed water to boiler 4) Impure water can also be used as cooling medium 5) Air leakage is comparatively less, hence less power is required to operate air pump Disadvantages 1) Design is complicated and costly 2) High maintenance cost 3) Occupies more space 4) Requires more circulating water
  14. 14. Parallel flow low level Jet condenser
  15. 15. Counter flow low level Jet condenser
  16. 16. High level Jet condenser
  17. 17. Ejector type Jet condenser
  18. 18. Down flow Surface condenser
  19. 19. Central flow Surface condenser
  20. 20. Inverted type Surface condenser  In this type of jet condensers, steam enters at the bottom of the shell and flows upwards.  Air extraction pump is placed at the top.  The condensate flows down and removed at the bottom where condensate pump is located.
  21. 21. Regenerative type Surface condenser  The condensers used in a regenerative method of heating the condensate are called regenerative type condensers.  In this type of condensers, the condensate after leaving the condenser is passed through the exhaust steam where the temperature is increased.  The condensate at high temperature can be reused as feed water to the boiler.  This increases the efficiency of the plant and minimise the fuel consumption.
  22. 22. Evaporative Surface condenser
  23. 23. Sources of air in Condenser 1) Air leakage from atmosphere at the joints of the parts which are internally under a pressure less than atmosphere 2) Air accompanied with steam from the boiler into which it enters dissolved with feed water 3) In jet condensers, a little quantity of air accompanies the injection of water in which it is dissolved
  24. 24. Effects of air leakage in a condenser 1) Lowered thermal efficiency 2) Increased requirement of cooling water 3) Reduced heat transfer 4) Corrosion
  25. 25. Methods of obtaining maximum vacuum 1) Air pump 2) Steam air ejector 3) De-aerated feed water 4) Air tight joints
  26. 26. Vacuum Measurement
  27. 27. Vacuum Efficiency It is defined as the ratio of actual vacuum to the maximum obtainable vacuum. Vacuum efficiency = Actual vacuum Maximum obtainable vacuum ö æ Vacuum efficiency = Actual Vacuum Absolute - pressure of steam Barometer Pressure ö ÷ ÷ ÷ ÷ ÷ ø æ ç ç ç ç ç è ö ÷ ÷ ø æ ç ç è ÷ ÷ ÷ ÷ ÷ ø ç ç ç ç ç è
  28. 28. Condenser Efficiency It is defined as the ratio of difference between the outlet and inlet temperatures of cooling water to the difference between the temperature corresponding to the vacuum in the condenser and inlet temperature of cooling water ö ÷ ÷ ÷ ø Rise in temperature of cooling water - æ Inlet temperature ç ç ç è ö ÷ ÷ ÷ ÷ ÷ ø Temperature æ ç ç ç ç ç è ö ÷ ÷ ÷ ø æ ç ç ç è of cooling water corresponding to vacuum Condenser efficiency =
  29. 29. Edward’s Air Pump
  30. 30. Two Stage Air Ejector

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