Gasification of Corn Stover

Corn stover refers to stalks, leaves and cobs that remain in fields after the corn harvest. This biomass can be used in producing ethanol. Corn stover is the primary biomass source being used for producing cellulosic ethanol in the United States (Wilhelm et al. 2007). Corn stover is the largest quantity of biomass residue in the United States. Around 120 million tons of biomass residue is available annually. This stover has the potential of supplying 23 to 53 billion liters of fuel ethanol to the U.S. transportation market, up to 10 percent of total gasoline needs. Corn stover is composed of about 70 percent cellulose and hemicellulose, and 15 to 20 percent lignin. Cellulose and hemicellulose can be converted to ethanol, and lignin burned as a boiler fuel for steam/electricity generation. The two important routes to converting corn stover into biofuels are: biological conversion and thermochemical conversion.  The thermochemical conversion involves gasification and pyrolysis.  In gasification, the stover is gasified and carbon monoxide, hydrogen and carbon dioxide in the synthesis gas are fermented into ethanol. Gasification takes place at high temperature in the presence of an oxidizing agent (also called a gasifying agent). Heat is supplied to the gasifier either directly or indirectly which raises the gasification temperature of 600–1,000 ° Oxidizing agents are typically air, steam, nitrogen, carbon dioxide, oxygen or a combination of these. In the presence of an oxidizing agent at high temperature, the large polymeric molecules of biomass decompose into lighter molecules and eventually to permanent gases (CO, H2, CH4 and lighter hydrocarbons), ash, char, tar and minor contaminants. Char and tar are the result of incomplete conversion of biomass.


Flow Diagram




Direct Gasifier
Gas cooler
Hot gas filter
Boost compressor


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