Lee J. Rosen

LOW NOx EMISSIONS IN A FUEL FLEXIBLE GAS TURBINE

In alignment with Vision 21 goals, a study is presented here on the technical and economic potential for developing a gas turbine combustor that is capable of generating less that 2 ppm NOx emissions, firing on either coal synthesis gas or natural gas, and being implemented on new and existing systems. The proposed solution involves controlling the quantity of H2 contained in the fuel. The presence of H2 leads to increased flame stability such that the combustor can be operated at lower temperatures and produce less thermal NOx. Coal gas composition would be modified using a water gas shift converter, and natural gas units would implement a catalytic partial oxidation (CPOX) reactor to convert part of the natural gas feed to a syngas before fed back into the combustor. While both systems demonstrated technical merit, the economics involved in implementing such a system are marginal at best. Therefore, Praxair has decided not to pursue the technology any further at this time.