Study On Biomass Gasification And Simulation Of Bio-oil Hydrogenation

China is an agricultural country with abundant biomass resources, which have great potential of being converted into various forms of energy. There are several ways for the recovery and utilization of biomass resources, of which gasification and fast pyrolysis are the two major ways. Traditional downdraft biomass gasifier is better than the updraft one in terms of its energy efficiency and tar content in the producer gas. However, the tar content at the exit of downdraft gasifier is still too higher for some specific applications (e.g. ICE), which limits subsequent utilization of the producer gas. At the same time, the bio-oil produced by fast pyrolysis usually contains a wide variety of substances such as acids, phenols, aldehydes, ethers and alcohols, which causes the low quality and instability of bio-oil. Therefore, in order to solve these problems, two researches were performed in this thesis:the first is the experimental study of an innovative downdraft gasifier, about which, the effect of equivalent ratio (ER) on gasification performance and tar content were investigated. The second is the simulation study of catalytic hydrogenation of bio-oil model compounds using Aspen Plus software, during which the effects of operating parameters (such as temperature and pressure, etc.) on product composition and yield were studied, and the purpose is to provide theoretical basis and scale-up support for its commercialization.The developed innovative two-stage downdraft gasifier in this work has a lot of improvement in its configuration compared to other two-stage downdraft gasifiers. In order to investigate its gasification performance, the effects of equivalent ratio (ER) on reduction zone temperature, producer gas composition, gas heating value, gasification efficiency and tar content were studied. The experimental results indicated that the tar content in producer gas generated by the gasifier was in a low level, and was even lower with the preheating of air, only238mg/Nm3. In addition, the heating value of the producer gas and gasification efficiency were much higher with the preheating of air compared to the case of without preheating, reaching the highest when the equivalent ratio (ER) is0.34, which are4409kJ/Nm3and63.7%respectively, and the producer gas has a better composition of18.5%CO、13.2%H2、1.8%CH4、11.1%CO2. Therefore, we think the optimized ER was between0.33and0.35for the gasifier.The simulation study of catalytic hydrogenation of bio-oil model compounds was also conducted in this paper. By selecting hydroxyacetone, hydroxyacetaldehyde, guaiacol and2-furanone as model compounds for bio-oil and Ru/C as the hydrogenation catalyst, subroutines in Fortran language were developed regarding the kinetic equations of catalytic hydrogenation of each model compounds, and were successfully implemented in Aspen Plus. Based on this customized model, the effects of temperature and pressure on hydrogenation performance of model compounds were studied by doing simulations, and it was found that200℃and24bar was the optimum conditions for the catalytic hydrogenation of bio-oil. Also, the data of material and energy balances for the catalytic hydrogenation process were obtained, which could provide theoretical basis and data support for bio-oil hydrogenation.