【作者】 苑塔亮；

【导师】 李志义；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2006， 硕士

【摘要】 本文设计并建立了一套间歇式超临界生物质气化实验装置。利用该装置,在水的近临界态和超临界态,以葡萄糖为生物质模型化合物,以制取氢气为目的进行实验研究。选用氧化钙为二氧化碳脱除剂,考察添加氧化钙前后,反应温度、反应压力、反应停留时间、葡萄糖初始浓度和Ca/C摩尔比等因素对气体样品组成和葡萄糖分解率的影响。在实验中,使用气相色谱仪定性定量分析气体样品,通过分析反应后液体样品的化学需氧量(COD)值来确定葡萄糖的分解率。 首先,在纯超临界水条件下进行实验研究。实验结果表明,温度和反应停留时间是实验的主要影响因素。在一定温度范围内,随着温度的升高,反应后的气体样品中氢气和甲烷含量增加,一氧化碳含量减少,葡萄糖分解率也逐渐增加。反应停留时间对气体组成影响较大,当停留时间延长,葡萄糖的分解率逐渐增加。反应压力在临界点附近对气体样品组成有一定影响。当葡萄糖初始浓度增加时,气体组分中甲烷含量上升。 在纯超临界水条件下,较理想的制氢反应条件为:温度在500℃左右,压力在临界压力(22.5MPa)以上,浓度在2.5～5.0%之间,反应停留时间在3～5min内。 其次,为了提高氢气的产量和增加葡萄糖的分解率,尝试在实验中添加氧化钙。在添加氧化钙的情况下,反应温度和反应停留时间仍然是影响实验结果的主要因素。压力在临界点附近对气化效果和葡萄糖分解率都有一定影响。当葡萄糖的初始浓度高于5%时,添加了氧化钙的葡萄糖分解率随着浓度逐渐增大而明显增大。 添加氧化钙后,较理想的制氢反应条件为:温度在500℃左右,压力在临界压力(22.5MPa)以上,浓度在2.5～5.0%之间,反应停留时间在3～5min内,Ca/C摩尔比在0.4～0.5之间。 最后,基于本文的实验研究结果以及参考其他研究者的结论,对超临界水中葡萄糖气化反应机理和反应路径进行了初步分析。综合对比后,提出了在反应过程中添加氧化钙作为二氧化碳脱除剂的超临界生物质气化制氢工艺路径。新的工艺可以提高氢气的产量和增加生物质的分解率。更多还原

【Abstract】 In this paper, the experimental equipment of supercritical biomass gasification with batch operation is setted up. Aimed at hydrogen production with the glucose as the model compound in the sub-supercritical or the supercritical water, the experimental study is carried on with this equipment. The CaO is chosen as the removing solvent for CO2. The effects of reaction temperature, reaction pressure, stay time, initial concentration of the glucose and Ca/C molar ratio on the decomposing rate of the glucose are studied. The chamical oxygen demand （COD） value is used to determine the decomposing rate of the glucose, and the gas chromatography is employed to analyse the gas outcome from the experiments quantitatively.At first, the experiments are run in the pure supercritical water. The results show that the temperature and the stay time are the main parameters of the experiments. As the temperature rising in the experimental range, the proportions of hydrogen and methane in the gas outcome from the reactor increase, the proportion of the CO decreases, and the decomposing rate of the glucose decreases. The stay time of the reaction have a great effect on the composition of the gas outcome. The decomposing rate of the glucose decreases as the increasing of the stay time of the reaction. The pressure also has the effect on the composition of the gas outcome at the critical point. The methane proportion increases as the intital concentration of the glucose increases.The ideal reaction parameters of the hydrogen production in the pure supercritical water are as following: temperature about 500℃, pressure above critical point （22.5MPa）, concentration between 2.5% and 5.0%, the stay time of the reaction within 3min⁵min.Secondly, in order to increace the proportion of the hydrogen and the decomposing rate of the glucose, the CaO is added in the experiments. In this case, the temperature and the stay time of the reaction are still the main parameters greatly effecting on the results of the experiments. The pressure has certain effect on the gasification and the decomposing rate of the glucose at the critical point. The decomposing rate rises a lot as the concentration increases with CaO, when the intital concentration of the glucose is more than 5%.The ideal reaction parameters of hydrogen production with CaO are as following: the temperature about 500℃, the pressure above the critical point （22.5MPa）, the concentration between 2.5% and 5.0%, the stay time of the reaction within 3min⁵min, the molar ratio of Ca/C between 0.4-0.5.At last, on the foundation of the experimental results in this paper and the results from other studies, the reaction mechanism and the reaction path are analyzed. After comparing, the technology of hydrogen production from biomass gasification in supercritical water with CaO as the removing solvent for the CO₂ is comfirmed. The new technology is able to raise the output of the hydrogen and increase the decomposing rate of the biomass.更多还原