5 Gas turbine cycles Report

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Politecnico di Milano MSc. Energy Engineering – Power Production Energy Conversion A Prof. Gianluca Valenti PROJECT 5 COMPARISON OF GAS TURBINE CYCLES a.y. 2015/16 Giulia Boschi Omar Brembilla Alessandro Mosca 2 The following project deals with a gas turbine power plant, and, in particular, its aim is to compare four different plant configurations. A – SIMPLE CYCLE Such configuration is the simplest we could ever find. It is made of only two turbomachines: a compressor and a turbine, both axials, and the only heat source is the burning of natural gas inside the combustor. Besides, we also need to include the filter house at the air intake and the silencer at the turbine discharge. Notice the presence of bleedings from the compressor to the first stages of the turbine, with the purpose of keeping the blades at reasonable temperatures, and the compressor leakages (point 10) that we will neglect in this argument. B – INTERCOOLED GAS TURBINE (IC) 3 Such cycle is derived from the simple one, with the exception that it introduces an intercooling. This means that we will compress the air flow from the ambient to an intermediate pressure, cool it down to the ambient temperature again, and go on compressing up to the maximum value of the cycle. This allows us to reduce the compression work, but we have to pay this with a g reater amount of fuel, in order to reach the same cycle maximum temperature. The effect will be an increase of the net power output, but the effects on the global cycle efficiency are not so easy to determine, since from the compressor point of view the efficiency improves, but the heat expenditure increases as well for the lower air temperature at the combustor inlet. Besides we have to consider the cost of a new component, and th e entropy generations…