Combustion of char-coal waste pellets for high efficiency and low NO{sub x}. Technical report, September 1--November 30, 1994

Illinois coals are prime candidates for use in Integrated Gasification Combined Cycle (IGCC) plants because of their high volatility and good char reactivity. In these plants, partial gasification of the coal in the presence of limestone eliminates the major portion of the sulfur species in the product gases, which are used as fuel for the topping cycle. The char produced is high in ash content, the major portion of which is calcium sulfide. It is also low in volatiles and of low density, compared to the parent coal. The economic success of the gasification route depends on the subsequent utilization of the residual char for raising steam for use in a Rankine cycle bottoming plant and/or preheating the air to the gasifier. Fluidized bed combustion of the char appears an attractive way of utilizing the char. Areas of concern in the fluidized bed combustion of the high ash, low volatility char are: attainment of high carbon conversion efficiencies; reduction of oxides of nitrogen emissions; reduction/elimination of corrosive chlorine species; reduction/elimination of sodium and other alkali species; and efficient usage of the calcium present in the ash to reduce sulfur compounds. The aim of the present project is to investigate ways of improving the carbon conversion efficiency, sulfur capture efficiency and NO{sub x} reduction during the fluidized bed combustion by pelletizing the low density char with coal and coal wastes using cornstarch or wood lignin as binder. During this first quarter, the parent coals and the chars to be tested have been analyzed. Particle size distributions have been measured. Sample pellets have been made evaluation of their properties