Raw syngas out of the reactor cannot be an "end product" because, to be used, it requires cooling and cleaning.
Gasification converts low or negative-value feedstocks into fuel and other eco-friendly marketable products.
Syngas is an abbreviation for the synthesis gas produced in gasification, a thermo-chemical process that converts any carbon-containing material into a combustible gas under restricted supply of oxygen. In case of biomass feedstock, the combustible gases that compose syngas are carbon monoxide (CO) and hydrogen (H2), together with a small amount of methane (CH4). It will also contain other non-combustible gases such as nitrogen (N2) and carbon dioxide (CO2). The composition of syngas is very dependent on the type of gasification process, gasification agent and gasification temperature.Based on the applications, the gasification process can produce two types of fuel gas:
Producer Gas. This type of fuel gas is generated in the low temperature gasification process (below 1000 deg C) and contains CO, H2, CH4, CxHy, aliphatic hydrocarbons, benzene, toluene, and tars (besides CO2, H2O, and N2 in case of gasification in air).
Syngas. This type of fuel gas is produced by high temperature (above 1200 deg C) or catalytic gasification. Under these conditions the biomass is completely converted into H2 and CO (besides CO2, H2O, and N2 in case of gasification in air). The H2 and CO components typically contain only about 50% of the energy in the gas, while the remainder is contained in CH4 and higher (aromatic) hydrocarbons. Syngas can also be made from Producer Gas by heating the thermal cracking or catalytic reforming. The oxidant for the gasification process can be either atmospheric air or pure oxygen. Gasification of biomass with air produces a low calorific value gas, which contains about 50% nitrogen and can fuel engines and furnaces, whereas gasification with pure oxygen results in a medium calorific value gas, free of nitrogen. This system also offers faster reaction rates than air gasification but has the disadvantage of additional capital costs associated with the oxygen plant.
Syngas or Producer Gas can be used to produce heat, steam, or electricity. Syngas filtered through appropriate membranes can also be used for the production of purified H2; the resulting syngas can be utilized for other hydrocarbon feeds.