Gasification: Difference between revisions

===== Counter flow (updraft) moving bed gasifier =====

In moving bed updraft gasifiers, the oxidant (most often air) is injected at the bottom of the gasifier and the product gas flows upward and exits at the top of the gasifier. In such gasifiers well-defined temperature zones are established, from the fuel drying section at the fuel inlet, the pyrolysis zone beneath the drying zone and the reduction zone where the combustion gases react with the char from pyrolysis and finally the combustion or glow zone at the bottom where the oxidant (air or oxygen combined with steam) is injected. The final burn-out of the char occurs on a moving grate through which the ash falls through into the ash outlet. The hot product gas from the glow zone going upwards is the heat carrier that heats up the fuel to reach the temperature to achieve pyrolysis and the drying prior to extracting the cooler gases at the top at a temperature where excessive tar condensation does not occur (typically at 200-400 °C).

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