Characterization of Feed Streams and Emissions from Biomass Gasification/Combustion at Fuel Ethanol Plants

Fuel and emission characteristics of co-products of the ethanol dry-grind process [distillers wet grains (DWG), concentrated distillers solubles (referred to as “syrup”), and distillers dried grains with solubles (DDGS)], and corn stover are evaluated. Biomass co-products from the dry-grind ethanol production process, particularly DDGS, are good sources for the electrical and thermal energy needed to operate the plant, and even contain sufficient energy to produce excess power that can be sold. However, the number of subsequent process steps required to reduce emissions to compliance levels, particularly nitrogen oxide, will be important in determining the economic viability of using biomass co-products from dry grind ethanol plants for energy production. The alkali metal content (potassium and sodium) of the ash is high (22 to 34 %) for co-products and corn stover. Such high levels of alkali metals can lead to ash fouling in combustion and steam generation units, and to potential agglomeration of bed material in fluidized bed systems.