Evaluation of NOx Production from Black Liquor Gasification-Gas Turbine Combustion Systems, 1998 International Chemical Recovery Conference Proceedings

This paper examines the emission of NOx from black liquor gasifiers integrated with combustion turbines for combined heat and electricity generation. This is done by first examining the fate of the fuel bound nitrogen in the gasifier, based on the literature on laboratory studies of black liquor and biomass pyrolysis and gasification. This provides an estimate for the NH3 concentration of the gasifier product gas of 30-300 ppmv dry, depending on gasifier type. The conversion of the NH3 to NOx in the gas turbine engine combustor in then examined. Four types of combustors are evaluated, with the greatest potential for NOx control indicated for the developmental richquench-lean combustor. Overall, assuming combustor technology presently available, the emission of NOx from the black liquor gasifier/combustion turbine engine system is indicated to be about 20-40 ppmv (15% O2 dry), which is essentially the NOx range of recovery furnaces. However, if significant removal of NH3 in the gas cleanup train between the gasifier and the gas turbine engine is practiced, or if combustors engineered to efficiently convert small concentrations of NH3 to N2 are developed, black liquor gasifier/gas turbine engine systems will exhibit a significant NOx advantage over recovery furnaces.