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Difference between revisions of "Gasification"
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Gasification process
Bas Davidis (talk | contribs) |
Bas Davidis (talk | contribs) (Gasification process) |
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< | <chem> C + O2 -> CO2</chem> ΔH = -349 kJ/mol (Char combustion) | ||
< | <chem>C + 1/2O2-> CO</chem> ΔH = -111 kJ/mol (Partial oxidation) | ||
<chem>H2 + 1/2O2 -> H2O</chem> ΔH = -242 kJ/mol (Hydrogen combustion) | |||
The main product of this phase is the thermal energy, while the combustion product is a gas mixture of CO, CO<sub>2</sub> and water. | The main product of this phase is the thermal energy, while the combustion product is a gas mixture of CO, CO<sub>2</sub> and water. | ||
==== Drying ==== | ==== Drying ==== | ||
During the drying phase, the moisture contained in the feedstock is evaporated. The amount of heat required is proportinal to the feedstock moisture content. Generally, the heat required derives from the other stages of the process. | |||
==== Pyrolysis ==== | |||
Pyrolysis is the thermochemical decomposition of organic compounds. In particular, the cracking of chemical bonds takes place with the formation of three different fractions: a solid, a liquid and a gaseous fraction. The pyrolysis reaction takes place with a temperature in the range of 250-700°C. It is an endothermic reaction and, as in the drying step, the heat required comes from the oxidation process. The pyrolysis of organic material can be schematized with the following overall reaction: | |||
When the feedstock is made of biomass, since cellulose is its main component, in this reaction the biomass can be indicated with the chemical formula of cellulose (i.e., C<sub>6</sub>H<sub>10</sub>O<sub>6</sub>) | |||
==== 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: | |||
<chem>C + CO2 +<-> 2 CO</chem> | |||