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"Fluidized Bed Biomass Gasification with Clay Catalyst"
- An Innovative and Appropriate Technology for Sustainable Development in Asia -

Focusing on Thermochemical Conversion

 Technologies for conversion of biomass to energy can be categorized into three groups, that is, direct combustion, biochemical conversion and thermochemical conversion. Among them, APEX has focused on thermochemical conversion, because efficiency of direct combustion is low especially in small scale, and biochemical conversion such as ethanol fermentation can only make use of limited part of biomass such as sugar and starch, but by thermochemical conversion we can convert almost all components of biomass to gas or liquid fuels efficiently.

Fluidized Bed Biomass Gasification with Clay Catalyst

 There are various types of technology for thermochemical conversion of biomass such as partial combustion fixed bed gasifier with air or oxygen as gasification agent, fluidized bed gasifier and combustor using sand as bed material, low temperature gasification using catalyst etc. However, partial combustion gasifier requires high temperature in order to avoid emission of tar, and in order to attain high temperature, a lot of biomass has to be burned. If we make use of catalyst, we can lower the gasification temperature, but the catalyst is expensive and easily subjected to deactivation. Also, the product gas of the partial combustion gasifier is low calory as contaminated with nitrogen. In order to obtain high calory gas, the gasifier requires oxygen, resulting increase of operational cost.

 In order to overcome these problems of existing technologies, APEX has developed a new gasification technology concept utilizing clay catalyst in circulating fluidized bed gasifier. The technology has been developed in collaboration with TUAT(Tokyo University of Agriculture and Technology), YDD(Yayasan Dian Desa, an Indonesian NGO) and BPPT(Badan Pengkajian dan Penerapan Teknologi, Agency for the Assessment and Application of Technology). Fluidized bed technology makes use of phenomena that solid particles are transformed into a fluidlike state through suspension in a gas or liquid. The new technology gasifies biomass efficiently by contacting biomass with clay catalyst in fluidized condition. Biomass is fed to the gasifier, where converted into gas and char (carbonaceous matter) catalyzed by clay under presence of steam. As the char is accumulated on the surface of the clay catalyst, the catalyst is deactivated. The catalyst covered by the char is then sent to regenerator, where char is burned with air. The catalyst regenerated by the removal of char and heated by combustion heat is returned to gasifier, where catalyzes gasification reaction again and provides heat necessary for the reaction. Mixture of ash derived from biomass and spent catalyst (clay) is obtained as byproduct, which is proper to be returned to soil for ensuring sustainable reproduction of biomass.


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