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Difference between revisions of "Gasification"
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Gasification technologies
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==== Reduction ==== | ==== Reduction ==== | ||
The reduction step involves the reaction between the products of the preceding stages of pyrolysis and oxidation, which results in the formation of the final syngas. The main reactions occurring in the reduction step are as follows: | The reduction step involves the reaction between the products of the preceding stages of pyrolysis and oxidation, which results in the formation of the final syngas. The main reactions occurring in the reduction step are as follows: | ||
<chem>C + | <chem>C + CO2 +<-> 2 CO</chem> (Boudouard reaction) | ||
<chem> | <chem>C + H2O <-> CO +H2</chem> (Reforming of the char) | ||
<chem>C + 2H2 <-> CH4</chem> | <chem>CO + H2O <-> CO2 + H2</chem> (Water gas shift reaction) | ||
<chem>C + 2H2 <-> CH4</chem> (Methanation) | |||
=== Gasification technologies === | |||
The reactors to gasify a pre-treated feedstock, called gasifiers, essentially differ from one another for mode of contact between the feed material and the gasifying agent, mode and rate of heat transfer, and residence time of the fed material into the reaction zone. Different technological solutions can be implemented to obtain different configurations. Principally, the mode of contact may be in counter-current, co-current, or cross flow, and the heat can be transferred from the outside or directly in the reactor using a combustion agent. The residence time can be in the order of hours (static gasifiers) or minutes (fluidized bed gasifiers). The main reactors used in the biomass gasification process are as follows: | |||
# Entrained flow reactor | |||
# Fixed bed reactor, either updraft (counter-current) or downdraft (co-current) | |||
# Fluidized bed reactor, either bubbling fluidized bed or circulating fluidized bed | |||
# Rotary kiln reactor | |||
# Plasma reactor | |||