Synthesis Gas Production with an Adjustable H2/CO Ratio through the Coal Gasification Process: Effects of Coal Ranks And Methane Addition

With the decline of oil reserves and production, the gas-to-liquids (GTL) part of Fischer–Tropsch (F-T) synthesis technology has become increasing important. Synthesis gas (H2 + CO) with a stoichiometric ratio (H2/CO) at 2 or ranging from 1 to 2 is generally used in major synthesis-gas-based chemicals production. There are growing interests in the development of an alternative technology, other than the expensive natural-gas-based catalytic process, for cost-effective production of synthesis gas with a flexible hydrogen/carbon monoxide (H2/CO) ratio. Direct production of synthesis gas using coal as a cheap feedstock is attractive but challenging due to its low H2/CO ratio of generated synthesis gas. Three typical U.S. coals of different ranks were tested in a 2.5 in. coal gasifier to investigate their gasification reactivity and adjustability on H2/CO ratio of generated synthesis gas with or without the addition of methane. Tests indicated that lower-rank coals (lignite and sub-bituminous) have higher gas...