鼓泡流化床稻草与污泥共气化试验

对工农业废弃物进行再利用对于保护环境和节约资源具有重要意义。本文在鼓泡流化床上进行了稻草与污泥共气化试验,分别分析了气化当量比、原料含水率和污泥掺混比对气化特性和焦油产量的影响。结果表明：当量比从0.2增加至0.4的过程中,产气中的可燃组分浓度、产气热值和气化效率均呈现先略有增大后逐渐减小的趋势,气化效率在当量比为0.25左右最大达到53.8%;在整个过程中,气化焦油产量随着当量比的增大而逐渐减小。原料含水率的增大对于气化具有削弱作用,随着含水率从5%增大到20%,产气中的可燃组分浓度均逐渐减小,产气热值、气体产率和气化效率在含水率为20%时均达到最低;焦油产量先增大后有所减小。在污泥掺混比从0增至30%过程中,H₂的浓度基本不变,CH₄和CO的浓度先增加后减小,产气热值和气化效率在掺混比为20%时均达到最好;焦油产量随污泥掺混比增加先逐渐减小后略微增大。     

Formation of tar and its characterization during air-steam gasification of sawdust in a fluidized bed reactor

The sawdust tar was generated from air-steam gasification in the fluidized bed reactor at atmospheric pressure. The gasification temperature and mass ratio of steam to sawdust were used as adjustable variables with which the amount of sawdust tar formation and the corresponding tar properties. Gel permeation chromatography (GPC) coupled with diode array detector (DAD) was employed to analyze the tar. It was found that the molecular weight distribution (MWD) of tar was unchanged under investigated conditions. The majority of the tar components are aromatic compounds, paraffin with conjugated bonds and olefin. Tar molecular weight (MW) depends on the H free radical amount, which is related to the steam added during the gasification. The steam can prevent the polymerization reaction and more conjugated side-chain compounds would be formed. In the end, the sawdust tar formation process has been described from the tar structure obtained.     

基于回收理念的生物质燃气焦油脱除研究进展

生物质气化是重要的可再生能源方式。焦油是生物质气化过程大规模工业化的主要障碍之一。为了提高生物质燃气用于内燃机和燃气轮机发电以及甲醇合成的效率,燃气中的焦油必须深度脱除至低于20 mg/m3。本文简述了焦油污染和堵塞燃气下游设备的危害,介绍了焦油的特征和分类,分析了基于回收过程的焦油脱除方法优势,评述了回收法焦油脱除的研究进展,阐述了水洗和油洗回收脱焦的典型应用实例。指出了以油洗回收法为基础,将焦油和微孔材料的孔径进行匹配,高集成度的吸附和膜分离多级耦合焦油深度脱除工艺,将成为脱除生物质燃气焦油的主要发展方向。     

煤气化合成气除尘用陶瓷膜研究进展

当前,世界各国均在研究增压流化床联合循环发电技术和整体煤气化联合循环发电技术中的高温除尘技术。介绍了陶瓷膜除尘分离的原理,以及其在国内外的应用和研究现状。认为陶瓷膜优点突出,在煤气化合成气除尘及高温气体除尘领域具有广阔的应用前景。     

Tar removal from the producer gas of a small scale downdraft gasifier using a fatty acid based,wet packed-bed scrubber

Small scale gasification combined heat and power (CHP) systems offer an alternative to diesel fuelled generators for power generation in remote communities and industrial sites. Tar and particulates in the producer-gas can damage the internal combustion engine generator and increase operation and maintenance costs. In this work, we present a novel trickle-bed scrubber using filtered waste cooking oil as a cost effective and easy-to-operate gas clean-up method for a small CHP system. The performance of the trickle-bed scrubber was compared against a packed-bed filter utilizing woodchips in a 20 kW_th downdraft gasifier. Used-cooking oil was selected as the solvent and woodchips as the bed-material as these are readily available, inexpensive, and can be recycled in the gasifier as fuel. A woodchip packed-bed filter reduced the tar and particulate matter (PM) in the producer gas from gasification of spruce chips (11% moisture) from 1.6 to 1.4 g/Nm³ and from 0.16 to 0.087 g/Nm³ respectively. The trickle-bed scrubber was able to reduce the tar and PM in the producer gas from gasification of pinewood (8% moisture) from 1.38 to 0.28 g/Nm³, and 0.209 to 0.082 g/Nm³, respectively. Tar and PM removal efficiency improved by 60% and 29% respectively. Components such as benzene, toluene, naphthalene, and biphenylene were the major tar components. After passing the trickle-bed, most tar was removed, with a preference for removal of multi-ringed aromatics and gravimetric tars. Parameters such as the tar and particulate concentration, feedstock moisture content, and feedstock source affect the performance of the gas clean-up system.     

Simulated biomass tar removal mechanism by a Quench Coupled with ADsorption Technology (QCADT)

Tar removal is a bottleneck in the smooth commercialization of biomass gasification technology. Based on introducing adsorption process into Quench Coupled with ABsorption Technology (QCABT) previously proposed by the author's group, Quench Coupled with ADsorption Technology (QCADT) has been developed to narrow this gap. Additionally, benzene and naphthalene, which are more similar to the real tar for containing aromatic ring structures, were adopted as light and heavy simulated tar, respectively. Also their removal behavior by QCADT was investigated. The results show that the removal mechanism of QCADT is similar to that of QCABT, except for the higher overall tar removal rate due to adsorption effect. Adsorbents with both micro- and narrow mesopores exhibit a better benzene removal performance, while narrow mesopores play dominant roles in naphthalene removal. Penetration adsorption loading of benzene and naphthalene on AC-1 can reach 0.38 g·g^-1 and 0.34 g·g^-1, respectively. The sawdust hardly has any tar removal effect. Combined micro- and meso-pores, will benefit both deep tar removal and large adsorption rate, providing a high tar removal efficiency.     

铜渣催化气化木屑的实验研究和热力学分析

以木屑为原料,在铜渣催化气化木屑的实验平台上研究了气化剂和载气对气体产物成分及热值的影响。根据实验结果,当水蒸气当量比为0.058时,焦油产率降低了约50%,氢气产率提高了63.04%,气化效率达75.03%。在优化的实验条件下基于能量平衡建立熔融铜渣催化气化木屑的热力学分析方法,得到铜渣、木屑及水蒸气之间的耦合关系,1250℃的熔融铜渣的余热高达1.773 MJ/kg,充分利用铜渣显热和潜热气化木屑产生的合成气热值可高达13319 kJ。在最优气化工况下,1 kg原料气化需要1.92 kg铜渣,热态铜渣催化气化木屑的能量利用率可达62.94%。     

Biomass tar recycling and destruction in a CFB gasifier

Conversion of biomass into producer gas by thermal gasification broadens the scope of biomass applications. Usually, tar has to be removed from the producer gas. Tar recycling within the gasification process may solve the associated waste problem and increase the system efficiency, provided tar is broken down under gasification conditions. We present results of tar recycling experiments at a Circulating Fluidised Bed gasifier. At 830 °C, from each of 15 main tar compounds 70-80% are broken down. Continuous recycling of tar would increase the tar content in raw producer gas by 50% at most and save about 3% fuel input.     

Recent advances in catalysts for hot-gas removal of tar and NH3 from biomass gasification

Biomass gasification produces a low to medium-BTU product gas (or syngas) containing primarily CO₂, H₂, CO, CH₄ and (C₂ + C₃), as well as some contaminants such as tars, NH₃, H₂S and SO₂. In order to achieve better efficiencies of the syngas applications, these contaminants must be removed before the syngas is used for internal combustion, gas engines, and in particular for fuel cells and methanol synthesis. Compared with the wet scrubbing technology, hot-gas cleanup technology to remove tar, ammonia and other contaminants at the “hot” state is more advantageous with respect to energy efficiencies. This paper provides an overview on recent advances in catalysts for hot-gas removal of tar and ammonia from biomass gasification. The review focuses on the recent development and applications of dolomite catalysts, iron-based catalysts, nickel and other metal supported catalysts, and the novel carbon-supported catalysts for hot-gas tar removal and ammonia decomposition. The barriers in applications of hot-gas cleanup processes and catalysts for full-scale biomass gasification, and areas for future research, are also discussed.     

Oxygen Gasification of Municipal Solid Waste in a Fixed-bed Gasifier

abstract Four waste materials, paper, wood, textile and kitchen garbage, in municipal solid waste were gasified separately with oxygen in a fixed bed reactor. The yields of products char, tar and gas, ...     

Validation and Application of a Kinetic Model for Downdraft Biomass Gasification Simulation

Biomass gasification is widely recognized as an effective method to obtain renewable energy. To accurately predict the syngas and tar compositions is a challenge. A chemical reaction kinetics model based on comprehensive gasification kinetics is proposed to simulate downdraft biomass gasification. The kinetic model is validated by direct comparison to experimental results of two downdraft gasifiers available in the literature and is found to be more accurate than the widely used Gibbs energy‐minimizing model (GEM model). The kinetic model is then applied to investigate the effects of equivalence ratio (ER), gasification temperature, biomass moisture content, and biomass composition on syngas and tar production. Accurate water‐gas shift and CO shift reaction kinetics are found critical to achieve good agreement with experimental results.     

Low-tar,highly burnable gas production from the gasification of pelletized palm empty fruit bunch

Gasification is an attractive method to convert lignocellulosic biomass into a combustible gas mixture for electricity and power generation. To control the tar concentration in the produced gas to be within the allowable limit of downstream applications, it is important for a gasification system to be integrated with a tar removal process. In this study, an integrated gasification system consisting of a downdraft gasifier and a secondary catalytic tar-cracking reactor was designed and tested for the gasification of pelletized oil palm empty fruit bunch. To further purify the producer gas, the system was also integrated with a cyclone, a water scrubber, and a carbon-bed filter. Biomass was fed at a rate of 5 kg/h, while the air equivalence ratio (ER) and the gasification temperature were set at 0.1 and 800°C, respectively. In total, 5 kg of the specially developed low-cost Fe/activated carbons (AC) catalyst was used in the hot gas catalytic tar-cracking reactor. Results indicate that our integrated gasification system was able to produce a clean burnable gas with a lower heating value (LHV) of 9.05 MJ/Nm³, carbon conversion efficiency (CCE) of 79.4%, cold gas efficiency (CGE) of 89.9%, and H₂ and CH₄ concentrations of 29.5% and 10.3%, respectively. The final outlet gas was found to only contain 32.5 mg/Nm³ of tar, thus making it suitable for internal combustion engine (ICE) application.     

热解温度及AAEM元素对生物质快速热解焦油的影响

生物质热解受热解温度、热解速率和碱金属及碱土金属(AAEM)元素影响显著。利用热裂解气相色谱质谱联用法(Py-GC/MS)针对热解温度及AAEM元素对生物质快速热解焦油的影响展开深入研究,通过样品热解前后的失重情况分析了热解温度及AAEM元素对生物质(稻壳和木屑、酸洗稻壳和酸洗木屑)热解特性的影响规律,利用气相色谱质谱仪(GC/MS)对热解焦油组分及含量进行了在线半定量分析,并对热解焦油组分分子量分布情况展开了讨论。结果表明生物质Py-GC/MS快速热解实验,酸洗脱除AAEM元素致使热解失重率减小。500~900℃范围内随温度的升高,大分子焦油成分逐渐减少,逐渐转化为轻质组分。AAEM元素限制了焦油前体的聚合,进一步抑制了含氧杂环类碳环(糠醛等)的生成。稻壳的热解焦油的相对分子质量主要分布在110~129。木屑快速热解焦油产率明显高于稻壳,且热解焦油中分子量分布广泛,含有更多较大分子量(150~209)的化合物成分。     

Syngas production through gasification and cleanup for downstream applications — Recent developments

In the present paper various gasification technologies/gasifiers and syngas cleaning options are critically reviewed keeping in view various types of feedstocks and various downstream applications of syngas such as power generation, chemicals and hydrogen production, liquid fuels production and synthetic natural gas (SNG) production. Recent developments on gasification technologies including fixed bed dry bottom (FBDB) gasification, power high temperature Winkler (PHTW) gasification, catalytic steam gasification, transport reactor gasifier as well as syngas cleanup technique including hot gas filter and warm cleaning are discussed. Techno-economic analysis of various gasifiers as well as syngas cleaning processes along with the world scenario of syngas production and its various downstream applications is also discussed.     

部分氧化对焦油模型化合物苯酚转化的机理

基于Richter等提出的碳氢化合物燃烧的详细反应机理,结合生物质气化焦油的部分氧化脱除方法,建立了生物质部分氧化的详细反应机理。与Jess的实验比较,验证了模型的准确性。 计算了以苯酚为焦油模型化合物在过量空气系数ER=0～0.2条件下的转化,表明氧气的加入提高了焦油的转化率和反应速率。适量的氧气能提高部分氧化的可燃气体的产率。基于ROP分析得到典型PAHs的生成率,结果表明环戊二烯基对于PAHs的形成和成长有重要的促进作用,活性OH和H自由基在焦油裂解为小分子过程中起主要作用。     

水蒸气/氧流化床两段煤气化制备低焦油合成气工艺实验

由下行床热解和提升管（或输送床）气化组合形成的流化床两段气化将煤气化反应过程解耦为煤热解和半焦气化两个反应阶段,热解产物完全进入气化反应器,利用其中的高温环境和输送的半焦催化作用分别实现焦油的热裂解与催化裂解,完成低焦油气化。利用该流化床两段气化的10 kg/h级实验室工艺实验装置,以榆林烟煤为原料、水蒸气/氧气作为气化剂,变化过量氧气系数ER、蒸汽炭比S/C、热解及气化温度等参数,研究水蒸气/氧流化床两段煤气化制备低焦油合成气的特性。结果表明,流化床两段气化系统可实现稳定运行（实验3 h以上）,在ER=0.36和S/C=0.15时,热解和气化的代表温度分别稳定在735℃和877℃,合成气的CO、CO₂、H₂、CH₄、C _n H _m 和N₂含量分别为14.33%、10.07%、18.39%、9.89%、1.82%和45.50%,相应的合成气产量达到1.8 m³/kg,低位热值8.99 MJ/m³,焦油含量0.437 g/m³,展示了制备低焦油合成气的技术特征。对于实际的长时间连续运行,更高的气化温度将使流化床两段气化具有更好的低焦油特性。     

水蒸气/氧流化床两段煤气化制备低焦油合成气工艺实验

由下行床热解和提升管（或输送床）气化组合形成的流化床两段气化将煤气化反应过程解耦为煤热解和半焦气化两个反应阶段,热解产物完全进入气化反应器,利用其中的高温环境和输送的半焦催化作用分别实现焦油的热裂解与催化裂解,完成低焦油气化。利用该流化床两段气化的10 kg/h级实验室工艺实验装置,以榆林烟煤为原料、水蒸气/氧气作为气化剂,变化过量氧气系数ER、蒸汽炭比S/C、热解及气化温度等参数,研究水蒸气/氧流化床两段煤气化制备低焦油合成气的特性。结果表明,流化床两段气化系统可实现稳定运行（实验3 h以上）,在ER=0.36和S/C=0.15时,热解和气化的代表温度分别稳定在735℃和877℃,合成气的CO、CO₂、H₂、CH₄、C _n H _m 和N₂含量分别为14.33%、10.07%、18.39%、9.89%、1.82%和45.50%,相应的合成气产量达到1.8 m³/kg,低位热值8.99 MJ/m³,焦油含量0.437 g/m³,展示了制备低焦油合成气的技术特征。对于实际的长时间连续运行,更高的气化温度将使流化床两段气化具有更好的低焦油特性。     

Catalytic gasification of woody biomass in an air-blown fluidized-bed reactor using Canadian limonite iron ore as the bed material

A Canadian limonite iron ore was tested for the first time as a catalytic bed material for air-blown gasification of pine sawdust at various equivalence ratios (ER, 0.20–0.35) on a pilot-scale fluidized bed gasifier, in comparison to a conventional olivine bed material. Effects of bed materials (iron ore and olivine) on tar formation and gasification efficiencies were comparatively investigated. The use of Canadian limonite iron ore as the bed material was found to be more active than olivine for tar reduction in the fluidized bed gasification of biomass at a small ER (?0.3), leading to a very low tar yield of 15–25 g/kg biomass at ER = 0.30. The yields of combustible gas (carbon monoxide hydrogen, methane and C₂ hydrocarbon gases) and cold gas efficiency were generally the highest at medium values of ER (0.25–0.30) for both bed materials. The iron ore was less active than olivine for producing combustible gases, leading to a lower cold gas efficiency (50% at ER = 0.30) compared to 75% for olivine. However, the use of the iron ore produced a higher yield of hydrogen than that of olivine in the gasification: 5.0 mol hydrogen per kg of biomass with the iron ore at ER = 0.30 which was about 25% higher than that with olivine.     

生物质间接液化一步法合成燃料二甲醚

结合合成气制备液体燃料二甲醚的技术特点，对生物质在不同气化介质中的气化工艺以及气体组分分布进行了分析，对生物质合成气的自有特点和组分调整等重要制备过程进行了分析探讨，参考煤气化制备二甲醚的工艺过程，提出了生物质间接液化一步法合成液体燃料二甲醚的工艺路线设想。     

松木屑和褐煤流化床的共气化特性

在流化床上以空气-水蒸气为气化介质,对松木屑和褐煤的共气化特性进行了试验研究。在828～928 ℃范围内考察了生物质掺混比例、空气当量比（ER）和水蒸气-燃料比（S/F）对气化气成分、热值、碳转化率及气化效率的影响。结果表明,在生物质掺混比例为50%时,①随着ER值从0.2增加至0.35,CO2含量增加,CO、H2、CH4和CnHm含量减少,气化气热值、碳转换率、气化效率先增加后减少,在ER=0.26时达到最大;②在ER=0.26,S/F从0增加至0.44时,CO2含量增加,CO和H2含量先增加后减少,CH4和CnHm含量减少,气化气热值、碳转化率和气化效率先增加后减少。试验结果表明,在松木屑掺混比例为50%和褐煤共气化过程中,气化气热值最高可达7819 kJ/m3。