Evaluation of thermal NOx emission characteristics of high efficiency gas turbines using refuse-recovered low BTU gases

Abstract

The paper evaluates thermal NOx formation characteristics of high efficiency gas turbines using refuse-recovered low Btu gases. First, an estimation model of nitric oxide (NO) formation density for the gas turbine is constructed by revising a model proposed by W. S. Y. Hung. Next, taking a gas turbine burning high Btu gas with a turbine inlet temperature of 1273 K as a reference case, its NO emission density is estimated. Parametric analyses are done on the parameters that greatly affect the NO formation characteristics for the reference gas turbine, and it is shown that there is a limit to the possible NO density reduction by only controlling these parameters. Thirdly, the effects on the NO density of increasing gas turbine efficiency, by incorporating a regenerator or by raising turbine inlet temperature, are investigated. It is shown that the NO density of a gas turbine with a high efficiency is estimated to be higher than the assumed environmental quality standard (EQS) value. Finally, by utilizing these results, the cases are investigated where refuse-recovered low Btu fuels such as pyrolysis gas from municipal refuse are used. It is shown that the NO densities in these cases are estimated to be notably lower than the EQS value. Further, it is demonstrated that the use of low Btu fuel does not necessarily assure a low NO density, since the NO density is not determined only by the heating value of the fuel.