Engineering Design Considerations for Methane Fermentation of Energy Crops: Fundamental Considerations. Annual Report, Second Year, January 1-December 31, 1989.

摘要

The goal of the project is the development of the scientific and engineering basis for a cost-effective system to produce methane from energy crops. The emphasis is in two areas that provide the greatest systems cost reductions - purification of biogas to high quality methane and high conversion rates that would lead to small reactors. Two significant contributions were made in 1989. Parameters controlling continuous production of biogas containing greater than 90 percent methane was shown to be easily and simply achieved from biomass digesters. 'Methane enhancement' was achieved by carefully defining the variables affecting carbon dioxide and methane solubilities and by using external carbon dioxide stripping from a recycled leachate. The second 'breakthrough' area was the achievement of stable and execeptionally high methane production rates in high solids semi-continuously fed digesters (referred to previously as 'dry fermentation' or 'anaerobic composting'). Provision of adequate nutrients, continuous feeding, and mixing enable low solid reactors to achieve high methane rates of 3 l/kg-d, with instantaneous rates as high as 20 l/kg-d.