Steam Gasification of Coal with Salt Mixture of Potassium and Nickel in a Fluidized Bed Reactor

Abstract

Australian coal loaded with a mixed catalyst of K2SO4+Ni(NO3)(2) has been gasified with steam in a fluidized bed reactor of 0.1 in inside diameter at atmospheric pressure. The effects of gas velocity (2-5 U-g/U-mf), reaction temperature (750-900 degreesC), air/coal ratio (1.6-3.2), and steam/coal ratio (0.63-1.26) on gas compositions, gas yield and gas calorific value of the product gas and carbon conversion have been determined. The product gas quality and carbon conversion can be greatly improved by applying the catalyst; they can also be enhanced by increasing gas velocity and temperature. Up to 31% of the catalytic increment in gas calorific value could be obtained at higher temperatures. In the experimental runs with variation of steam/coal ratio, the catalytic increments were 16-38% in gas calorific value, 14-57% in carbon conversion, 5-46% in gas yield, and 7-44% in cold gas efficiency. With increasing fluidization gas velocity and reaction temperature, the unburned carbon fi-action of cyclone fine for catalytic gasification decreased 4-18% and 13-16%, respectively, compared to that for non-catalytic gasification.