HOT GAS CLEANING OF BIOMASS DERIVED SYNGAS BY CATALYTIC FILTER CANDLES

摘要

Biomass derived syngas is widely expected to establish the local energy supply. The context comprisessyngas utilisation via dual fluidized bed gasification to heat and power generation and moreover the conversion intosynthetic natural gas, liquid fuels or chemicals. Essential requirement for the application and further conversionprocesses is the syngas purity. The syngas purification focuses on gaseous and solid impurities, whereas mainly tarsand particles (ash, coke, attrition of bed material) are addressed, which are effected by the syngas generation process.The present paper concentrates on hot gas cleaning of biomass derived syngas by dual fluidised bed gasification ofbiomass. Within the examination, the performance of a catalytic filter candle is investigated under the impact of realsyngas conditions with regard to hot gas cleaning capability. The applied catalytic ceramic filter candle ismanufactured by Pall Filtersystems GmbH, Production Site Schumacher Crailsheim, Germany. A catalytic filtercandle is integrated into the freeboard of the industrial operating biomass gasifier in Guessing, Austria. Hence thecandle is exposed to gasifier raw gas conditions. A slip stream of raw syngas is sampled over the catalytic filtercandle. The characteristic of the catalytic filter candle is examined with regard to particulate separation and tardecomposition, since the raw syngas contains high amounts of solid particles and gaseous tar impurities. Particulatesare separated by the porous material of the filter candle. Tar conversion is obtained by Ni-containing parts of the filter candle, which acts as catalyst for the reforming of the tar components. The clean syngas slip stream downstream of the filter candles is compared to the gasifier raw gas with regard to the particulate and the tar content. Hence, thecapability of particulate separation and tar conversion over the catalytic filter candle is determined. These results are assessed with view on the feasibility of hot gas cleaning by catalytic filter candles, which could potentially reduce the efforts of gas cleaning units at industrial operating devices.