Characteristics And Kinetic Of Biomass Pyrolysis And Steam Reforming Tar

There is lots of biomass resources in China,which produces a large amount of agricultural and forest wastes every year.In this paper,the factors affecting the pyrolysis products were investigated by using an internal component reactor,and steam reforming experiments were carried out on the liquid products to remove tar.The detailed conclusions are drawn as follows:（1）Pyrolysis experiment was conducted on biomass with thermogravimetric analyzer.It was found that biomass pyrolysis can be divided into three stages:water removal,volatile analysis and carbonization.Volatilization is the main stage of pyrolysis reaction,the temperature range is 250-400℃,and the weight loss rate is about 70%.（2）The internal component reactor was used to conduct biomass pyrolysis experiment,which mainly investigated the effects of reaction temperature,particle size and biochar catalysis on biomass pyrolysis products.The results show that with the increase of temperature,the yields of char and tar decrease,and the content of pyrolysis gas increases,and H₂ accounts for 21.02%of the total gas volume at 900℃;The reduction of particle size has little effect on char and pyrolysis gas,while the yield of tar decreases by 9.1%.Meanwhile,the content of anthracene oil in tar increases.The total yield of gas is 14.53%in the catalytic experiment of char with large particles.（3）Steam reforming experiment was carried out on tar in a micro fluidized bed,and the difference of products between pyrolysis and steam reforming was investigated.In the pyrolysis process,the gas yield and total carbon conversion increase with the increase of temperature.In the steam reforming process of tar,the total carbon conversion in gas products reaches 92.34%at 950℃and SP=30%.The influence of steam partial pressure on gas components is different.The formation rates of CO and CH₄ increased with the increase of partial pressure.The H₂ generation rate decreases gradually,and the rate stable period expands.The CO₂ generation rate has a maximum value at 850℃.（4）The activation energy of gas products（H₂,CO,CO₂ and CH₄）,total carbon conversion in gas products and the activation energy of tar conversion in the process of steam reforming of tar were calculated by homogeneous model.The corresponding values were 90.10,42.01,58.56,64.92,61.44 and 63.26 k J/mol,respectively,which were significantly lower than those of tar pyrolysis.