Production of Substitute Natural Gas from Coal

Abstract

The goal of this research program was to develop and demonstrate a novel gasification technology to produce substitute natural gas (SNG) from coal. The technology relies on a continuous sequential processing method that differs substantially from the historic methanation or hydro-gasification processing technologies. The thermo-chemistry relies on all the same reactions, but the processing sequences are different. The proposed concept is appropriate for western sub-bituminous coals, which tend to be composed of about half fixed carbon and about half volatile matter (dry ash-free basis.) In the most general terms the process requires four steps 1) separating the fixed carbon from the volatile matter (pyrolysis) 2) converting the volatile fraction into syngas (reforming) 3) reacting the syngas with heated carbon to make methane-rich fuel gas (methanation and hydro-gasification) and 4) generating process heat by combusting residual char (combustion). A key feature of this technology is that no oxygen plant is needed for char combustion iv