Coal gasification in a system with a damped circulating fluidized bed

Abstract

Experiments are conducted on the steam gasification of Borodino coal in a two-chamber gas generator. The generator is based on a circulating fluidized bed with damping of gas motion by the packing. The mean size of the coal particles is 0.2 mm. Heat from the combustion chamber is sent to the gasification chamber by the circulation of a disperse powder (electrocorundum) between the chambers. The chambers are filled with spherical packing (diameter 50 mm, porosity 0.5). The size of the electrocorundum particles is 0.3 mm. The heat of combustion of the gasification products is 8195 kJ/m³. The unburned residue is 5% in chemical terms and 2% in mechanical terms. The model proposed for the gas generator consists of one heat-balance equation each for the combustion and gasification chambers. The model is consistent with the experimental data. On the basis of the model, the optimal generator parameters are found: temperature 900°C in the gasification chamber and 1020°C in the combustion chamber; proportion of coal sent to the gasification chamber 36%; chemical efficiency 40%.