Coal Gasification in CO2 and Steam: Development of a Steam Injection Facility for High-Pressure Wire-Mesh Reactors

Abstract

The development of a steam injection facility and a new control system for steam gasification experiments in a high-pressure wire-mesh reactor have been described. The design is based on preheating the steam path to prevent condensation during experiments. Steam is allowed to contact the coal sample only instants before the temperature of the sample is ramped. Results from experiments in helium, CO2, and steam at pressures up to 30 bar (1000 °C s-1 to 1,000 °C) have been compared for experiments extending to 60 s at peak temperature. The occurrence of a minimum in the conversion vs pressure diagrams, previously observed by numerous researchers, appears to be related to the reactivity of the gasifying agent and the holding time. The minimum, observed at shorter holding times in steam compared to CO2, appears related to the consumption of secondary char deposited during the pyrolysis stage. At 10 and 20 bar, the sample appears to be completely consumed in steam in about 60 s, while after 60 s in CO2, the pr...