Flow Diagrams of Some of the Regenerate Cycles Used in Gas Turbine

Flow Diagrams of Some of the Regenerate Cycles Used in Gas Turbine Points : Flow Diagrams of Some of the Regenerate Cycles Used in Gas Turbine Power Plant, Regenerative Cycle, Inter Cooled Cycle, Evaporative Cooling Cycle Regenerative Cycle In this system the heat of exhaust gases from turbine is utilized in heating the compressed air or a counter flow heat exchanger transfer, exhaust heat to the compressed air before it enters the combustor. The amount of fuel needed to heat the air to combustion temp. is reduced by to 25% . This increase the efficiency and reduced the fuel consumption of the gas turbine system. There are many types of regenerative cycles are used in gas turbine power plant system sum of are enlisted below.
1. Inter Cooled Cycle
2. Evaporative Cooling Cycle
3. Reheat Cycle
4. Intercooled Steam — injected Cycle
5. Intercooled Reheat Steam injected Cycle
1. Inter Cooled Cycle In the intercooled cycle, a heat exchanger is placed in the air path between low — and high — pressure section of the compressor, show in fig, compressor of cool air requires less work than compression of warm air. This heat exchanger is designed to cool the air and reduced the amount of work required iii the high pressure section of the compressor, increasing both power output and efficiency. The intercooler can be a direct contact (Evaporative) or a extended surface type heat exchanger. 2. Evaporative Cooling Cycle The evaporative cooling cycle enhances gas turbine perform once primarily by cooling the compressor inlet air. An evaporative cooler at the inlet of compressor cools the combustion air by the evaporation of water. Evaporative coolers are limited to reducing the inlet air dry bulb temperature by up to 90% of the difference between the dry bulb and wet bulb temperatures. After evaporative cooling, the compressor inlet air is cooler and more dense. Since compressor are constant volume machines. This result in a higher mass flow through the gas turbine and increase the poor output. Evaporative condors are normally used in bed. Dry climate where the cooling effect is more pronounced. Water used with evaporative cooler often contains dissolved. Solids such as sodium and potassium which, in combustion with sulfur in the fuels, arc principal ingredients in hot gas path corrosion. For this reason, water quality and the presentation of water carry over must be considered carefully when using evaporative cooling.

3. Reheat Cycle The gas turbine reheat cycle is analogous to the steam turbine reheat cycle. The hot gasses are partially expanded through the turbine, reheated by a second stage combustion and returned to the turbine. This cycle is more complex than the standard gas turbine cycle. The reheat cycle is more efficient. To protect the reheat combustor the high pressure turbine is required to lower the temperature.

4. Intercooled Steam — injected Cycle The inter cooled steam injected gas turbine (ISTIG) cycle is similar to the steam injected cycle, inlet air is compressed in the low-pressure compressor and diverted through a water cooled heat exchanger. The cooled air is then discharged to the high pressure compressor inlet. ‘[he air temp is lowered by inter cooling to reduce shaft work of the high pressure compressor, there by increasing power output and efficiency. The hot water from the heat exchanger can be used to preheat feed water entering the [IRSG. This further increases efficiency. The basis arrangement for the intercooled steam injected cycle is shown in fig.

5. Intercooled Reheat Steam injected Cycle The intercooled reheat steam-injected gas turbine (IR — STIG) cycle employs compressor inter cooling similar to the intercooled steam-injected cycle. The combustion products are refried in a reheat combustor after partial expansion in the turbine The cycle increased the power output and efficiency.