ISO 9001 Certification industrial super heater and re heater for power station reheat cycle

Industrial reheater Introduction

1. A reheater has derived its name from reheating the steam at a stage after expansion to a certain pressure (Not till the condenser pressure). The main objective of the reheater is to increase the dryness fraction (moisture content of the steam at the last blade of turbine).

2. But due to this an additional work also is extracted from the turbine due to two stage expansion. So, work output increases. But also the steam uses extra heat to raise its pressure in the second stage after first expansion.

3. So, increase or decrease in efficiency is dependent on which of the above is more.

4. Concluding, it is used to increase the dryness fraction and also to increase work output when you have high amount of heat input.

Reheater Function

1. Therefore the number of reheat stages can not be many as the pressure drop will reduce efficiency of thermal cycle.The steam pipes and reheater coils are to be so designed to limit the drop to 2–3%.

2. The control valves in reheat steam path is not desirable.Systems using HP LP bypass require these valves to control steam flow during bypass operation.

3. The efficiency of the Reheat cycle can be improved by increasing the pressure and temperature of steam entering into the turbine. As the initial pressure increases the expansion ratio of the turbine also increases and the steam becomes quite wet at the end of expansion.

Main Advantage

The main advantage of reheat cycle is to reduce the specific consumption and consequently reduce the size of the boiler and other auxilaries for the same power.The reheat cycle is preffered for the high capacity above 100 MW plant.

Differences

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