What is Biomass Gasification?
Gasification is an important process to be mentioned with relation to co-firing. Gasification is a thermochemical process converting solid or liquid carbon-based fuels into a gas (syngas, which in case of gasification of biomass can be called bio-syngas). Syngas is rich in a number of components like CO, H2, CO2, H2O, and CH4, whose proportions depend on the raw material composition and on the gasification conditions such as pressure and temperature. Gasification takes place in the presence of an external oxidizing agent (oxygen, air or steam) and heat. The addition of heat can occur directly (by partial oxidation of the fuel) or indirectly by heat transfer. Unlike combustion, in gasification the amount of the external oxidizing agent is lower, hence only a relatively small portion of fuel is used to generate the required heat. There are two basic types of gasification – direct and indirect. There are three basic types of gasifiers – fixed bed, fluidised bed, and entrained flow gasifiers.