Steam boiler spare parts superheat and reheat Dehai Boiler reheater in boiler
Superheat and reheat System
1. Superheat and reheat steam temperatures should not be allowed to increase beyond the rated value as it will result in metallurgical problems in superheater and reheater tubes and also turbine components.
2. On the other hand, steam temperature lower than rated value will result in higher cycle heat rate. Typically a temperature reduction of 10 deg C in large capacity power plant will result in about 0.3 % increase in plant heat rate. Hence it is essential to maintain the superheat and reheat temperatures within a narrow range around the rated values.
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
| Type | Advantages | Disadvantages | Supporting method |
| Pendant-type | 1.Firm structural support | 1. Flow blockage by condensed steam 2. Needs slow restart to purge the water that accumulates in the bottom. | supported from above |
| Inverted-type | 1.Proper drainage of the condensed steam | 1. Lack the structural rigidity, especially in high speed gas flow | Supported from below |
| Horizontal -type | 1. Proper drainage 2. Good structural rigidity. | 1. They do not view the flam directly so they are mainly from the convective type | Usually supported in the vertical gas ducts parallel to the main furnace. |
Bending
Measuring
Squeezing
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Coal Fired Reheater In Boiler Spare Parts For Thermal Power Plant Images
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