Research For Air Injection Technology Used On Gas Turbine

Air injection gas turbine utilizes extra compressor to compress air from theenvironment, the air stays dry or goes through saturator to be humidified before beingheated by the exhaust gas of the gas turbine, the heated air is injected into the combustorfor the purpose of increasing output power and efficiency. Doctor Michael Nakhamkin,president of Energy Storage Power Corporation, developed and owns the patents on the useof air injection technology for gas turbine power augmentation. Air injection technology isused in some factories in USA, but in our country, such a new ideal is not being noticed atall. In this article, parameters of injected air on the influence of gas turbine performancesare researched with Matlab and Simulink.Two working patterns of air injection gas turbine, the first one is keeping the amountof fuel unchanged, the second is delivering the most output power, are discussed underdifferent conditions of parameters of injected air. Compressor working point, speed of T-Cshaft and temperature of exhaust gas are calculated with different amount of injected air inorder to confirm the highest amount of injected air. Results show that with the air massincreasing, in both two working patterns, output and efficiency of gas turbine is increasing.The second pattern, which delivers the most output, has bigger changing extent than thefirst one. Moisture of injected air has an effect on output power of gas turbine. Outputpower and efficiency increase as moisture rises. With moisture of injected air rising,compressor working point gets better. Output power of the second pattern has biggerchanging extent than the first one, while changing extent of efficiency is almost the same asthe first one. Through choosing the working pattern reasonably according to output power,gas turbine delivers request output power, at the same time, has higher efficiency.In order to solve the problem of over-speeding of T-C shaft, the air should be injectedinto the gas turbine at two separate injection point. This method can further increase outputpower and efficiency as well. The amount of air injected at the second injection point mustbe assigned to confirm power turbine works within exhaust temperature and gastemperature restriction.Comparing performance of gas turbine, STIG and Air Injection (Dry Air Injection andHumid Air Injection) with each other by steady-state simulation, the conclusion is made that power and efficiency of Humid Air Injection gas turbine, whose injected air humidityis0.5, are less than STIG by1.5%and3.3%with the same amount of injected gas.