生物质气化发电技术研究进展

化石能源枯竭和环境污染两大难题日渐成为社会发展的枷锁,人类亟需寻找绿色清洁能源推动社会可持续发展。生物质具有可再生性、原料丰富和清洁低碳的特点,拥有巨大应用潜力。生物质气化发电技术作为生物能利用的方法之一,不仅可以替代传统能源,还能避免能源利用过程中带来的环境污染问题。本文介绍了国内外生物质气化发电技术研究进展,包括气化设备研究、生命周期评价和发电工艺研究等,为生物质气化发电技术的研究提供参考和借鉴。     

Production of ultrapure hydrogen from biomass gasification with air

An integrated process has been proposed for the production of ultrapure hydrogen from biomass gasification with air. The process consists of an air-blown bubbling fluidized bed gasifier, a steam reformer, and a water-gas-shift membrane reactor. A non-isothermal model has been developed to simulate the fluidized bed gasifier, and a one-dimensional model has also been developed to simulate the steam reformer. The simulation results are compared with the experimental data, and good agreement is obtained. Based on the simulation results, the thermodynamic analysis of the integrated process is carried out. The simulation and analysis provide a quantitative tool for gaining insight into the process.     

The technical feasibility of biomass gasification for hydrogen production

Biomass gasification for energy or hydrogen production is a field in continuous evolution, due to the fact that biomass is a renewable and CO₂ neutral source. The ability to produce biomass-derived vehicle fuel on a large scale will help to reduce greenhouse gas and pollution, increase the security of European energy supplies, and enhance the use of renewable energy. The Värnamo Biomass Gassification Centre in Sweden is a unique plant and an important site for the development of innovative technologies for biomass transformation. At the moment, the Värnamo plant is the heart of the CHRISGAS European project, that aims to convert the produced gas for further upgrading to liquid fuels as dimethyl ether (DME), methanol or Fischer–Tropsch (F–T) derived diesel. The present work is an attempt to highlight the conditions for the reforming unit and the problems related to working with streams having high contents of sulphur and alkali metals.     

Hydrothermal biomass gasification

Different hydrothermal biomass gasification processes are under development. In contrast to biomass gasification processes without water, biomass with the natural water content (“green biomass”) can be converted completely and energetically efficiently to gases. Depending on the reaction conditions, methane or hydrogen is the burnable gas produced. Some processes use catalysts. In recent years, significant progress was achieved in the development of various hydrothermal biomass gasification processes. However, some challenges still exist and technical solutions are needed before large-scale production facilities can be built.     

结构参数和操作参数对生物质气化制氢技术的影响

生物质气化制氢技术不仅是一种清洁能源技术,而且有助于缓解我国能源压力,优化能源结构。介绍并对比了生物质制氢的主要方法,包括生物法和热化学法制氢技术。热化学法制氢技术的工业化发展较受关注,主要包括气化法、热解法和超临界转化法,其中气化法因产氢量高、废弃物少和工艺要求较易实现等优点,成为目前热化学法制氢的主要方法。阐述了生物质气化过程的基本原理,分别从结构参数(物料特性、气化剂、气化炉种类、催化剂)和操作参数(反应温度、当量比、水蒸气配气比)系统地分析了影响生物质气化过程的主要影响因素及其变化规律,指出应从优化结构参数和操作参数上促进生物质气化制氢技术的发展。     

生物质超临界水气化制氢技术的研究现状

介绍了国内外生物质超临界水气化制氢技术的研究进展,并对该技术的反应机理、影响因素、不同的催化剂、催化机理进行了评述.指出对气化反应机理的研究应该以关键化合物为基础;在反应器形式和催化剂一定的条件下,影响气化结果的主要因素是反应温度、进料浓度、加热速率、碱性化合物添加剂;碱性化合物添加剂和碳催化剂或金属催化剂结合使用可能会实现高效催化气化过程.     

Ultrahigh temperature water gas shift catalysts to increase hydrogen yield from biomass gasification

Noble metal (Rh, Pt, Pd, Ir, Ru, and Ag) and Ni catalysts supported on CeO₂–Al₂O₃ were investigated for water gas shift reaction at ultrahigh temperatures. Pt/CeO₂–Al₂O₃ and Ru/CeO₂–Al₂O₃ demonstrated as the best catalysts in terms of activity, hydrogen yield and hydrogen selectivity. At 700 °C and steam to CO ratio of 5.2:1, Pt/CeO₂–Al₂O₃ converted 76.3% of CO with 94.7% of hydrogen selectivity. At the same conditions, the activity and hydrogen selectivity for Ru/CeO₂–Al₂O₃ were 63.9% and 85.6%, respectively. Both catalysts showed a good stability over 9 h of continuous operation. However, both catalysts showed slight deactivation during the test period. The study revealed that Pt/CeO₂–Al₂O₃ and Ru/CeO₂–Al₂O₃ were excellent ultrahigh temperature water gas shift catalysts, which can be coupled with biomass gasification in a downstream reactor.     

Solid oxide fuel cells in combination with biomass gasification for electric power generation

Biomass, a source of renewable energy, represents an effective substitute to fossil fuels. Gasification is a process that organics are thermochemically converted into valuable gaseous products(e.g. biogas). In this work, the catalytic test demonstrated that the biogas produced from biomass gasification mainly consists of H_2,CH_4, CO,and CO_2, which were then be used as the fuel for solid oxide fuel cell(SOFC). Planar SOFCs were fabricated and adopted. The steam reforming of biogas was carried out at the anode of a SOFC to obtain a hydrogen-rich fuel.The performance of the SOFCs operating on generated biogas was investigated by I–V polarization and electrochemical impedance spectra characterizations. An excellent cell performance was obtained, for example,the peak power density of the SOFC reached 1391 mW·cm~(-2) at 750℃ when the generated biogas was used as the fuel. Furthermore, the SOFC fuelled by simulated biogas delivered a very stable operation.     

生物质催化气化实验研究

在常压流化床上进行了生物质在水蒸气条件下的实验研究。实验装置主体由常压流化床反应器和固定床催化裂解反应器组合而成。生物质原料为木屑,焦油裂解催化剂分别选用煅烧白云石和镍基重整催化剂。实验结果表明,H2/CO(H/C)的摩尔比随着气化温度、水蒸气质量/生物质质量（S/B）的升高迅速增加,但催化裂解温度变化对H/C的影响较小。另外,在催化裂解反应器中使用催化剂种类不同,H/C也不同。本文采用两段催化裂解,一段催化剂采用煅烧白云石,二段采用镍基催化剂,焦油裂解率达到96.70％。采用两段催化裂解,不但可以提高焦油的裂解率,增加了H2和CO收率,净化生物质裂解气,而且可以防止镍基重整催化剂失活,延长其使用寿命。     

Investigation on the reactions influencing biomass air and air/steam gasification for hydrogen production

Hydrogen could be the energy carrier of the next world scene provided that its production, transportation and storage are solved. In this work the production of an hydrogen-rich gas by air/steam and air gasification of olive oil waste was investigated. The study was carried out in a laboratory reactor at atmospheric pressure over a temperature range of 700 ­ 900 °C using a steam/biomass ratio of 1.2 w/w. The influence of the catalysts ZnCl₂ and dolomite was also studied at 800 and 900 °C. The solid, energy and carbon yield (%), gas molar composition and high heating value of the gas (kJ NL^− 1), were determined for all cases and the differences between the gasification process with and without steam were established. Also, this work studies the different equilibria taking place, their predominance in each process and how the variables considered affect the final gas hydrogen concentration. The results obtained suggest that the operating conditions were optimized at 900 °C in steam gasification (a hydrogen molar fraction of 0.70 was obtained at a residence time of 7 min). The use of both catalysts resulted positive at 800 °C, especially in the case of ZnCl₂ (attaining a H₂ molar fraction of 0.69 at a residence time of 5 min).     

钙基吸附剂循环吸附性能对增强式生物质气化制氢的影响研究

钙基吸附剂循环CO₂吸附性能对增强式生物质气化连续高效制氢起重要作用。采用将CaO颗粒分散在惰性载体中的方法并结合挤压成型技术制备了合成吸附剂颗粒。为了筛选循环吸附性能较好的吸附剂,在热重分析仪上进行了循环吸附性能测试。基于热重测试结果开展了吸附剂循环利用条件下的增强式生物质气化制氢实验。结果表明：添加惰性载体能延缓CaO烧结,提高吸附剂的循环吸附能力;挤压成型过程会破坏吸附剂原有孔隙结构,导致吸附剂颗粒吸附性能不同程度降低,其中CaSi75p、CaAl75p和CaY75p三种吸附剂循环性能较好;添加以上三种吸附剂颗粒均可显著提高生物质气化合成气中H₂浓度及产率,5次循环过程中气体成分和产率变化不大,表明吸附剂循环吸附能力和稳定性较好。     

Effects of alkali- and alkaline-earth-metals on hydrogen generation during fluidized bed gasification of artificial waste

We evaluated the effects of Na, K, Ca, and the steam-to-biomass (S/B) ratio on gasification efficiency during syngas production. The results show that H₂ production was positively correlated with the S/B ratio. However, increases in the S/B ratio were limited because excessive steam decreased the reactor temperature and hampered the gasification process. Regarding the effects of alkali metals on syngas composition, we found that the addition of either Na or K increased the molar percentages of H₂ and CO, but decreased CH₄ and CO₂. The results also clearly show that the addition of Na or K improved the yield of syngas, the carbon conversion efficiency, and the cold gas efficiency. Improvements were especially pronounced with K. Furthermore, Ca had different interactions with Na and K during gasification. When Na and Ca existed simultaneously, H₂ production was enhanced.     

生物质超临界气化制氢产物高压吸收法分离的气液相平衡分析

通过高压吸收法可以将生物质超临界水气化制氢的气体产物中的CO₂与H₂分离.基于修正的UNIFAC模型、SRK状态方程以及MHV2混合规则，建立了生物质超临界气化制氢产物高压吸收法分离的气液相平衡的计算模型，讨论了CO₂与H₂分离过程中压力和温度等参数对分离效果的影响.计算结果表明：随着分离器中压力的升高，气相产物中H2的摩尔分数增加，CO₂摩尔分数迅速下降，气相中H₂的收率不断降低；随着温度升高，气相产物中H₂的摩尔分数减小，CO₂摩尔分数上升，气相中H₂的收率增加；然而，高压吸收的方法不能将气体产物中的CO、CH₄、C₂H₄、C₂H₆与H₂分离.     

Performance assessment of a fixed-bed gasification pilot plant for combined power generation and hydrogen production

Large-scale hydrogen production through near zero emissions gasification plants represents a reliable technology which is being seriously considered for its potential economical implications. However, the application of these technologies is currently subject to high capital and operating costs. This needs great scientific and technical effort to optimize the processes and the equipment, to reduce the hydrogen production cost.In this context, a flexible and fully equipped pilot platform has been built up in the Sotacarbo Research Centre, in order to study several integrated gasification and syngas treatment process configurations for a CO₂-free combined production of hydrogen and electrical energy, to be used in medium and small-scale commercial plants. The platform includes pilot scale fixed-bed up-draft gasifiers, equipped with a flexible and complete syngas treatment line.This paper reports the main results obtained in the pilot plant during the last experimental campaign which has been carried out to improve the plant performance. In particular, a series of experimental tests has been performed in order to optimize the coal gasification process in different operating conditions. Moreover, a mention of the overall plant performance, based on the experimental results, has been presented, with particular reference to hydrogen, carbon and pollutant emissions.     

生物质半焦的催化气化动力学特性

采用恒温热重分析法对稻草的催化气化反应动力学进行了研究,同时研究了生物质对石油焦气化的催化作用。采用修正随机孔模型对气化反应转化速率与转化率的关系进行了拟合计算,得到生物质焦气化的活化能和指前因子。结果表明,加入催化剂后半焦的气化反应活性增大,活性顺序为：加入K+半焦> 加入Ca2+半焦> 加入Mg2+半焦> 原半焦> 酸洗后半焦,表明了生物质焦能明显提高石油焦的气化活性。不同半焦气化的活化能大小顺序为：加入K+半焦<加入Ca2+半焦<加入Mg2+半焦<原半焦<酸洗后半焦,表明了生物质半焦的加入能降低石油焦气化的活化能。     

生物质半焦气化及应用研究现状

介绍了近些年来生物质半焦气化及应用的研究现状,主要分析了不同气化剂和催化剂对生物质半焦气化的影响、生物质半焦作为催化剂对生物质气化及焦油产物催化裂解及其吸附重金属等吸附性能的研究。     

生物质半焦气化及应用研究现状

介绍了近些年来生物质半焦气化及应用的研究现状,主要分析了不同气化剂和催化剂对生物质半焦气化的影响、生物质半焦作为催化剂对生物质气化及焦油产物催化裂解及其吸附重金属等吸附性能的研究。     

生物质气化技术研究现状及其发展

生物质气化技术是洁净利用生物质能的有效方法之一。综述了生物质气化剂气化技术及其影响可燃气成分的主要因素,着重介绍几种常见的生物质气化剂在气化过程中发生的主要化学反应和在国内外的研究及应用现状。通过气化技术性能的对比,提出了研究开发经济上可行、效率较高的气化剂气化技术,同时阐明了我国生物质气化技术上亟待解决的难题,为我国在今后生物质气化剂气化领域的发展提供方向。     

国内外生物质气化设备研究进展

生物质是重要的可再生能源,生物质气化技术在国内外得到了广泛应用。本文综述了国内外固定床、鼓泡流化床、外循环流化床、内循环流化床、双循环流化床的结构。固定床安装简单,但焦油较多;外循环流化床燃烧效率高,但回料装置较难控制;内循环流化床不易结焦、氢含量高且不用考虑返料问题;双流化床结构复杂但焦油量少。将对固定床和流化床进行对比,认为固定床安装简单适合农村地区,流化床应不断改进和完善,更适应工业化生产。