Methane from coal gasification

Synthesis gas is obtained either from methane reforming or from coal gasification (see Coal conversion processes). Telescoping the methanol carbonylation into an esterification scheme furnishes methyl acetate directly. Thermal decomposition of methyl acetate yields carbon and acetic anhydride,... 

Synthetic Natural Gas. Another potentially very large appHcation of coal gasification is the production of synthetic natural gas (SNG). The syngas produced from coal gasification is shifted to produce a H2-to-CO ratio of approximately 3 to 1. The carbon dioxide produced during shifting is removed, and CO and H2 react to produce methane (CH, or SNG, and water in a methanation reactor. 

Synthesis gas consists of a nonhydrocarhon mixture (H2,CO) ohtain-ahle from more than one source. It is included in this chapter and is further noted in Chapter 5 in relation to methane as a major feedstock for this mixture. This chapter discusses the use of synthesis gas obtained from coal gasification and from different petroleum sources for producing gaseous as well as liquid hydrocarbons (Fischer Tropsch synthesis). 

Lee, A. L., Methanation for Coal Gasification, Clean Fuels from Coal... 

Near term options include primarily the unconventional natural gas resources (Western tight gas sands, Eastern Devonian gas shales, geopressured aquifers, and methane from coal deposits). Mid-term options include coal gasification (peat... 

A tube-wall reactor, in which the catalyst is coated on the tube wall, is conceptually ideally suited for highly exothermic and equilibrium-limited reactions because the heat generated at the wall can be rapidly taken away by the coolant. Previous work (1) has numerically demonstrated that for highly exothermic selectivity reactions, the optimized tube-wall reactor is superior from both steady state production and dynamic points of view to the fixed-bed reactor. Also, the tube-wall reactor is being advanced as a possible reactor for carrying out methanation in coal gasification plants (2). From a reaction engineering point of view, it therefore seems appropriate to analyze the reactor for the analytically resolvable case of complex first-order isothermal reactions. 

The purge gas from the methanol synthesis unit contains mainly methane. Depending upon the size of the plant, this stream may be reformed to supplement the synthesis gas produced from coal gasification. 

Fischer-Tropsch (FT) technology converts synthesis gas produced by reforming of methane or coal gasification into waxy products. Long alkanes (-CH2 -chains) produced by using FT synthesis are chemically similar to polyethylene. Lubricating oils derived from isomerization of FT waxes are gaining interest due to increased demand for lubricants with the advanced performance and environmental benefits described earlier. 

The production of methane from coal does not depend entirely on catalytic methanation, and, in fact, a number of gasification processes use hydrogasification, that is, the direct addition of H2 to coal under pressure to form methane (Anthony and Howard, 1976) ... 

Methane, which has more than 20-fold the greenhouse activity of CO2, is usually not released from coal gasification plants, but some emission may be linked to the production of the coal in deep mines [3]. 

The (additional) costs of C02 capture in connection with hydrogen production from natural gas or coal are mainly the costs for C02 drying and compression, as the hydrogen production process necessitates a separation of C02 and hydrogen anyway (even if the C02 is not captured). Total investments increase by about 5%-10% for coal gasification plants and 20%-35% for large steam-methane reformers (see also Chapter 10). 

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