Entrained-flow systems The main feature of entrained-flow gasification is the requirement for a very finebiomass grain size, even smaller than 0.1 mm. This size makes biomass easier to be carried out by the gasification medium. Biomass can be introduced in the reactor either at a dry form or even as slurry (pulverized biomass mixed with water). The retention time of biomass inside the reactor is only a few seconds and thus in order to achieve high conversion rates, higher temperatures are applied (between 1200 and 1500°C). At these temperature levels, the resulting ash melts, cools down and eventually accumulates as slag. Apart from higher temperature, entrained-flow gasification usually takes place at elevated pressure (pressurized entrained-flow gasifiers) reaching operating pressures even up to 40 and 50 bars. The existence of such high temperatures and pressures requires more sophisticated reactor design and construction materials used.. These gasifiers require large scale projects so as to be cost effective and are mostly common in fossil fuel applications and rarely with biomass feedstock. This is mainly due to the need for biomass special pre-treatment (fine grinding, drying) and the consequent high cost for this preparation. bioenergynet/articles/technology/innovation/1343-basic-designs-of-biomass-gasifiers
Posted on: Wed, 19 Jun 2013 22:17:33 +0000
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