Humid Air Turbine - Combined Cycle Hybrid

The Humid Air Turbine (HAT) cycle is an intercooled gas turbine-based cycle which utilizes generation of water vapor by directly contacting pressurized air leaving a compressor of the gas turbine with hot water in a counter-current humidifier and circulating the water leaving the humidifier to recover heat from the aftercooler and the stack gas. The resulting advantages of the cycle are: (1) high thermal efficiency (2) high specific power output (3) low NOx emissions. Despite these advantages the cycle has not been commercialized as the development costs are very high since the cycle requires an intercooled gas turbine and the relative size of the gas turbine expander has to be much larger than the gas turbine compressor than existing designs.The Combined Cycle (CC) utilizes in addition to a gas turbine a steam turbine. The exhaust heat from the gas turbine is utilized for the generation of steam which is admitted into the steam turbine. This cycle also has a very high thermal efficiency but a lower specific power output while the NOx emissions are typically higher than what can be achieved by the HAT cycle. Many combined cycle plants have been built and operated successfully over the last 25 years.

Benefits

The resulting advantages of the cycle are: (1) high thermal efficiency (2) high specific power output (3) low NOx emissions.

Date of release