High Quality Seamless Gas-fired Boiler Super heater And Re heater steam pipes
High Quality Seamless Reheater
1. As the name suggests reheater, it reheat the steam so that the temperature can be raised further and work done by IPT can be increased
2. generally after high pressure turbine the exhaust pressure and temperature will be 33–35kg/cm2 and 340–345degree C
So in order to increase the temperature of HP exhaust it is sent to reheater ,so flue gas passing over the tubes makes the steam to attain the temp back around 530–540degree C.
3. Now based on boiler design the reheater placement is decided ,for PF boiler it's between first pass and second pass of boiler and in cfbc rehater section is completely in 1 St section of second pass boiler
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.
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.
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
1.Proper drainage of the condensed steam
1. Lack the structural rigidity, especially in high speed gas flow
Supported from below
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.