Study Of Updraft Biomass Air Gasification And Tar-Reducing Technology

The use of biomass energy goes with the development of human society all the time. Since human beings entered into the industrial era, huge amounts of fossil energy had been exploited and used and it brought serious pollution to the environment. So, biomass energy came back into the view of human beings with wider using foreground. Biomass gasification, which can translate biomass into the clean gas, is an important manner of using biomass and the technology is value in realizing the distributing energy supply and adapt to the distributing modality of biomass energy.This dissertation studied air gasification technology of rice huck and corn cob by updraft biomass gasifier. How the equivalence ratio influences the gasification effect was firstly studied. The results showed that as accretion of the equivalence ratio, the axial temperatures increased, the content of CO and H2 were apt to augment, the CO2 and CH4 fell, the gas low heating value, the gasification efficiency and the carbon conversion efficiency all decreased, while the gas productivity increased. It turned up that the optimal equivalence ratio was 0.28 and corn cob was preferred as gasification material.Secondly, this dissertation further studied the establishment of gasification process when equivalence ratio was 0.28. It included the establishment of temperature field and stabilization process of gas compositions. It was induced that the both needed about 20min, and it showed the latter depends on the former for existence.Again, this dissertation studied the variety of gas compositions in different reaction zones in the gasifier. It was induced that CO2 mostly came from oxidation layer, CO and H2 from reduction layer and CH4 from pyrogenation layer.Finally, to the question that there is more tar in the gas of the updraft gasifer, this dissertation brought forward a new decoking technics based on delamination feedstock, according to the characteristic of the tar and updraft gasifer, that can make it come true to filter the tar and reuse its energy at the same time avoiding the water pollution brought by the wet decoking method. The size of the material particle and the thickness of the material layer were two improtant parameters of the technics above. The results showed that the smaller the particles were and the thicker the layer was, the higher the decoking efficiency was. The decoking efficiency was up to 80%. This new decoking technics is an effective method that can filter tar and reuse its energy.