Effects of using Hydrogen-rich syngas in Industrial gas turbines while maintaining fuel flexibility on compressor design

摘要

Most of the current industrial gas turbine systems are designed to operate with conventional fossil fuels. Recently, the use of Low Calorific Value (LCV) fuels gained interest, particularly, Hydrogen rich Syngas resulting from coal and solid waste gasification. When LCV fuels are used the performance and behavior of the engines could significantly change and modifications may be needed. For instance, due to the relatively low heating value the fuel mass flow rate will be much higher than natural gas, increasing substantially the mass flow through the turbine. This leads to a decrease of demand for air from the compressor, which results in increased back pressure, reduction of stall margin and possible compressor instability. This paper presents a preliminary study to pave the way to the design of a 300 MW industrial gas turbine's compressor with the objective of operating efficiently with Hydrogen rich syngas, while maintaining the flexibility for a quick switch to natural gas in the event of gasifier failure or breakdown of feedstock supply. NASA Rotor 37 is used as the test vehicle to provide design concepts because of its simplicity in being a single stage compressor and the availability of experimental data for the CFD model validation. Geometric modifications were performed on the rotor to shift the working line towards an estimated lower air mass flow rate working line. Further modifications were investigated in order to maintain the design point compressor efficiency primarily based on sweep and lean of the blade. Once the new working line geometry was obtained, inlet variable guide vane (IGV) effects were explored to allow the compressor to shift to the original working line without further changes to the blade shape.