UTILIZATION OF BIOMASS AND ORGANIC WASTES BY GASIFICATION: EVALUATION STUDY, CONCEPTUAL DESIGNS AND MINIPLANT DATA

摘要

The project described here is aimed at studying the chemical and technical feasibility of gasification of specialrnbiomass products. This paper contains an evaluation of research demands, the conceptual designs of representativernexperimental facilities for two promising applications and experimental data of miniplant facilities for kinetic considerations.rnOf all considerable biomass materials, two major groups are pointed out which had not yet been consideredrnfor energy supply. Conceptual designs are described for both groups:rn1) Gasification of organic wastes containing more than 80% water at high pressurern2) Two-stage pyrolysis/gasification for herbaceous biomass at atmospheric pressurernConsidering the first concept, sewage sludges, algae and organically polluted industrial effluents belong to therntarget educts. At roughly 600℃ and 30 MPa these educts are converted to a hydrogen-rich product gas, preferablyrnutilized for electricity generation.rnExperiments with glucose and other model compounds in a continuous miniplant yielded high carbon gas efficiencies.rnExperiments in a batch autoclave using real biomass (wood, straw, sewage sludge) gave similar efficienciesrnas obtained with model substances.rnThe objective of the second concept is the development of a two-stage fluidized-bed gasifier converting herbaceousrnresidual biomass into syngas with low tar and dust content, considering the special chemical and physicalrnproperties of these educts. A pyrolysis step at operating temperatures (600℃) below ash softening is combinedrnwith an entrained flow gasifier to convert intermediate pyrolysis products.rnInvestigations of biomass pyrolysis were performed discontinuously in a small fluidized-bed facility.rnHeterogeneous incineration and gasification rates of carbons and cokes, formed under fluidized bed conditionsrnwere determined using a thermobalance, a differential tube reactor and a fluidized bed of sand.