The low Btu gas (LBG) combined gas and steam turbine power cycle is a potentially attractive alternative to the direct coal fired steam cycle because of the potential for low sulfur emissions and high overall cycle efficiency. However, LBG may contain ammonia (NH3) which could be converted to nitrogen oxides (NOx) under typical combustion conditions. This paper examines the effects of LBG composition and combustor design on NOx emissions. Low Btu gases of varying compositions were synthesized from bottled gases and fired in three atmospheric pressure flame reactors: diffusion flame reactor, flat flame reactor and catalytic reactor. Nitrogen oxide emissions were found to be most sensitive to the concentrations of NH3 and hydrocarbon fuel gas in the synthetic LBG. Lowest NOx emissions were produced by the diffusion flame reactor operating at near stoichiometric conditions and the catalytic reactor operating fuel rich.

This project is designed to develop a family of novel NO x control technologies, called Second Generation Advanced Reburning which has the potential to achieve 90+% NO x control in coal fired boilers at a significantly lower cost than SCR. The eighth reporting period (July 1-September 30, 1997) included experimental and final report preparation activities. Experiments on high-temperature reactions of sodium carbonate were completed at the University of Texas in Austin. This study revealed that sodium can affect NO concentrations under both fuel-rich and fuel-lean conditions. The engineering design conducted during the previous reporting period was converted into retrofit hardware for the AR-Lean system and initial test results are presented and discussed. All information presented in this report is in summary form since a Draft Final project

The high efficiencies obtained in a combined gas-turbine/steam-turbine power cycle burning low Btu gas (LBG) make it a potentially attractive alternative to the high sulfur emitting direct coal-fired steam cycle. In the gasification process, much of the bound nitrogen in coal is converted to ammonia in the LBG. This ammonia is largely converted to nitrogen oxides (NOx) in conventional combustors. This paper examines the pressurized bench scale performance of reactors previously demonstrated to produce low NOx emissions in atmospheric laboratory scale experiments. LBG was synthesized in a catalytic reformer and fired in three reactors: a catalytic reactor, a diffusion flame, and a stirred reactor. Effects of scale, pressure, stoichiometry, residence time, and preheat were examined. Lowest NOx emissions were produced in a rich/lean series staged catalytic reactor.

The environmental aspects of the conceptual base-load, combined gas-steam turbine power plants designed by General Electric and Westinghouse in Phase II of the Energy Conversion Alternatives Study (ECAS) were analyzed. Each contractor had developed a combined cycle design which incorporated an integrated coal gasifier producing low-heat-content fuel gas, as well as a design fueled by coal-derived liquid purchased from an off-site producer. The conceptual power plants each produced some 60 to 900 MWe (gross), employing gas turbine inlet temperatures of 1600–1900 K. Equilibrium combustion gas properties were calculated for each system, and kinetic calculations were made for NOx production. The systems burning gaseous fuel were estimated to meet NOx emission standards. Neither design which used liquid fuel was estimated to meet NOx standards because of the high nitrogen content of the coal-derived synthetic liquid fuel.

As part of DOE'S Clean Coal Technology program, afield evaluation of Gas Reburning-Sorbent lnjection (GR-Sl