Condenser : study report, Essays (university) of Mechanical Engineering

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Report on Condenser

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Contents

• Introduction:................................................................................................................................................
• Components of Steam Condenser...............................................................................................................
• Types of Steam Condenser..........................................................................................................................
• Performance evaluation of condenser:.......................................................................................................
• Conclusion:..................................................................................................................................................
• Reference....................................................................................................................................................

Parallel Flow Low Level Jet Condenser: In this jet condenser, both cooling water and exhaust steam enter the condenser from the top and mix directly leading to heat transfer during falling of water through the steam. The wet water pump collects cooling water and condensed steam along with wet air. No air pump and make-up pump are required. High Level or Barometric Jet Condenser: On the basis of hydrostatic law, high level or Barometric jet condenser is designed. In this arrangement, the hot well is at ground level. The condensate extract pipe from condenser directly enters hot well. Cooling water pump pumps the cooling water at side near to the top of the condenser chamber. The exhaust steam enters from the side near to the bottom of the condenser and directly mix with cooling and leads to rapid condensation. The condensate along with cooling water falls by gravity into the hot-well through vertical tail pipe. There is no need of extraction pump. The air pump at the top of the condenser extracts out uncondensed steam and air. Ejector condenser: This system comprises of vertical tube having series of cones or converging nozzles. Cooling water falls from 2 to 6m height and enters converging nozzle at high speed. The exhaust steam enters from side way of the cylindrical condenser, into nozzles and meets cooling water. It condensates and creates vacuum, which in turn leads more steam to enters through momentum of falling water. The mixture of cooling water, condensed steam, uncondensed steam, and wet air discharged into the hot well via bottom divergent nozzle. Non-return valve in exhaust steam inlet prevents a sudden backward rush of water into the turbine exhaust pipe in case of sudden failure of water supply to the condenser. This requires more make-up water compared to other jet water condenser. It is less expensive. It is small, simple, and reliable. It is suitable for small power generation unit. Surface Steam Condenser or Non-Mixing type: A barrier is placed in tis system to prevent direct contact of cooling water and exhaust steam. Cooling water flows through numbers of water tubes while exhaust steam passes over them. The heat transfer takes place through surface of tubes. In some cases, steam flows through an array of steam tubes while cooling water is sprayed over them. Condensation process is slower as compared to jet steam condensing. A surface condenser mainly consists of a cast iron shell. The shell is cylindrical in shape and closed at both ends to form a water box. A tube plate is located between each cover head and the shell. Several water tubes are fixed to the tube plates. The shell is provided with exhaust steam inlet at the top and condensed steam outlet at the bottom. It requires two pumps. One pump to pump cooling water through the water tubes under pressure and other pump to remove wet air, condensates from the bottom of the condenser shell. Surface steam condensers are classified mainly into two types. Two flow condenser: The cooling water travels twice from inlet-water box to end water box and reverse back Multi flow condenser. In multi-flow process, the water box has many partitions leading more circulation of cooling water. This enhances heat transfer rate. However more power is required to circulate the cooling water. According to the direction of flow of steam the surface steam turbine can be classified as Down Flow Surface Condenser: It has cooling water pipes. Steam from top of the condenser vessel passes over the cooling water pipes. Temperature with its partial pressure falls as it moves downwards and it condenses. The condensate pump removes condensate at bottom. Central Flow Surface Condenser: It has arrays of tubes with the suction pipe of the air extraction pump at center. Steam enters radially inward and condensates over water tubes. The condensate flows radially towards the an removed by the condensate extraction pump. Inverted Flow Type Surface Condenser As name indicates, steam enters from bottom and passes upwards over water tubes.

Regenerative Type Surface Condenser: The condensate so formed surface condenser enters through tubes over which entering exhaust steam passes. This increases the temperature of the condensate to be uses as feed water. Evaporate Steam Condenser: Exhaust steam flows in to array of tubes, while cooling water is sprayed over it. With help of air (natural or forced) fast evaporation takes place. The cooling water is collected in water trays and reused again.

Performance evaluation of condenser:

Vacuum Efficiency It is the ratio of the actual vacuum to the maximum obtainable vacuum. Condenser Efficiency It is the ratio of rise of temperature of cooling water to the difference between the temperature corresponding to the vacuum in the condenser and inlet temperature of cooling water.

Conclusion:

The report has made intensive study about condenser. For good and efficient condenser, use circulating water should be less. It depends on a little auxiliary power. Its condensation effectiveness should be high. It must use minimum cooling surface area per kW capacity. Reference

1. HVAC-chillers , BEE code
2. Modern air conditioning practice, Norman Harris 3)ISHRAE journal