Entrained-flow oxy-gasification of pulverized coal in CO2-H2O-O2 environment.

Abstract

Combustion or gasification of coal in nitrogen-free environment (CO2-H2O-O2) is a promising technology contributing to reduce the carbon footprint in the energy industry. Accordingly, this will make it quite easy to capture practically pure carbon dioxide for subsequent storage. The study presents numerical investigation of the entrained-flow oxy-gasification processes of pulverized coal in CO2-H2O-O2 environment. A numerical methodology for describing oxy-fuel gasification processes has been developed and tested. A study of the influence of the absorption of gas coefficient on the calculation results was carried out. Studies have been conducted on the effect of the excess oxygen ratio, the oxygen concentration in the blast, and the amount of moisture on the physicochemical processes and the composition of the syngas for the gasifier under consideration. It is shown that increasing the oxygen concentration in the blast allows stabilizing the ignition and combustion of pulverized coal at low excess oxygen ratio. The dependence of the chemical efficiency on the main regime parameters is determined. The results showed that a decrease in the excess oxygen ratio from 0.43 to 0.33 leads to an increase in combustible losses from 0.15 to 45% for this gasifier. In the mode with high fuel conversion in the gasifier, the produced syngas with a caloric value of 9.26 MJ/m3 comprised of CO, 40.3; H2, 32.4; and CO2, 25.5 (vol.% dry).