合成气乙醇发酵的微生物研究

生物质合成气发酵是一种独特的、经济可行的乙醇生产新方法,它包括气化和发酵两个方面,对环境改善和能源供给有积极的意义.在合成气发酵产乙醇的微生物中,Clostridium ljungdahlii和Clostfidium carboxidivorans P7最有应用价值.它们利用合成气的途径是wood-ljungdahl途径.文章概述了合成气发酵产乙醇的菌种和培养条件,建立了生长动力学模型,提出了合成气发酵产乙醇工业化过程中存在的问题和应用前景.     

我国生物质能源现代化应用前景展望(二)——生物质制备液体燃料的转化途径

利用可再生生物质资源转化制备液体燃料已成为全球关注的热点。常见的生物质能源原料主要有草本植物、木本植物、微藻和脂肪类生物质资源,丰富的生物质资源为生物质液体燃料的生产提供了广泛的原料来源,也为生物质能源的多样性发展提供了坚实的物质基础。不同的生物质原料种类和转化方式可生产出性能各异的多种液体燃料,主要包括醇类燃料(乙醇、丁醇等)、烃类燃料和生物柴油等,由此构建出生物质转化制备液体燃料的转化途径网络。醇类燃料的生物质转化途径主要包括生物质直接发酵、生物质合成气发酵、生物质合成气化学合成等;烃类燃料的生物质转化途径主要有生物质液化加氢、微藻热化学途径、生物质合成气费托合成、生物质发酵脂肪酸加氢及油脂类加氢途径等;生物柴油的转化途径主要有油脂酯交换和微藻萃取酯交换。在这些液体燃料的转化途径中,只有生物质发酵制乙醇途径和油脂酯交换途径基本实现了商业化应用,其他大部分转化途径仍处于开发阶段。     

生物质合成气发酵生产乙醇的工艺分析

介绍了生物质合成气发酵制备乙醇的工艺过程。采用Aspen plus软件对工艺过程建立模型,模拟计算乙醇的产量。针对影响乙醇产量的主要参数进行了灵敏度分析,结果表明:气化过程中氧气与干生物质质量比对乙醇产量影响显著,且比值为0.4时,乙醇产量最大;而气化过程中过多蒸汽的加入会降低乙醇产量;发酵过程中CO和H2转化率的提高有利于乙醇产量的增加。     

生物质能源转换技术与前景

开发和利用生物质能,能够获得气体、液体、固体和电力等形式的能源。本文描述了沼气及其综合利用、热解气化、发酵乙醇、能源植物、压块成型、垃圾能源回收和发酵产氢等生物质能源转换技术。     

马克斯克鲁维酵母制备生物质乙醇研究进展

利用高温酵母进行高温乙醇发酵,因其能量损耗低、发酵速度快、染菌机率低等优点,成为生物质乙醇发酵生产的新方向。相比传统酵母,马克斯克鲁维高温酵母具有良好的耐温适应能力、更宽泛的底物利用能力、良好的发酵性能、超强的分泌能力、适于分子生物学操作等优势,在生物质乙醇发酵方面显示巨大潜力。本文从底物利用能力、基因重组方法、发酵方法等方面总结了马克斯克鲁维酵母在生物质乙醇发酵方面的发展概况。     

生物质生产燃料乙醇技术的研究

介绍国内外以及上海的生物质生产燃料乙醇技术应用和发展现状,概述了燃料乙醇生产的生物质原料和生产方法,并分析了生产技术存在的主要问题。最后,提出了上海未来生物质燃料乙醇生产的发展方向。     

燃料乙醇炼制系统优化与碳减排研究进展

生物质是丰富可再生的碳源,以糖、淀粉、秸秆纤维素或其他生物质原料高效生产燃料乙醇,可减少化石能源的需求,其中以木质纤维素为原料的第二代燃料乙醇具有广阔的发展前景。与化石能源相比,燃料乙醇具有环保、经济、可再生的优势,但其在生产工艺技术、经济效益和环境影响等方面仍需要深入研究。近年来,通过开展燃料乙醇炼制系统优化及全生命周期分析研究,有力地促进了燃料乙醇技术进步,推动了燃料乙醇碳减排相关研究。文章主要论述了近年来燃料乙醇生产技术的发展,重点对燃料乙醇系统的模拟优化和碳减排研究进展进行了总结,并对燃料乙醇发展趋势进行了展望,以期为燃料乙醇的可持续发展提供参考。     

合成气和培养基组分对C.autoethanogenum发酵产乙醇的影响研究

以合成气发酵菌株Clostridium autoethanogenum DSM10061为研究对象,研究改良DSM培养基640,添加玉米浆、焦油含量和产物浓度对合成气发酵的影响.结果表明:玉米浆浓度为0.175g/L时利于合成气乙醇发酵.适量的焦油有利于乙醇的生成,抑制乙酸的产生.低浓度的乙醇和乙酸能促进对应产物乙酸和乙醇的生成,但随着浓度的升高,乙醇和乙酸均会严重抑制产物的生成.     

国外可再生能源文献信息

一个生物质热解产能的新评估系数；日本用作能源的稻草数量、资源量和应用前景；湿生物质生产能源时的蒸气再压缩除湿；铂阳极直接乙醇质子交换膜燃料电池；柴油发动机使用甲基大豆脂肪酸盐、乙醇、柴油掺和燃料的排放特性；乙醇／汽油燃料对四冲程摩托车发动机排放特性的影响；[编者按]     

第二代和第三代生物燃料发展现状及启示

第二代生物乙醇以生物质为原料,包括纤维素乙醇和纤维素生物汽油两种产品。目前已建有示范装置和/或工业装置的纤维素乙醇生产技术包括硫酸/酶水解-发酵技术、硫酸水解-发酵技术、酸水解-发酵-酯化-加氢技术、酶水解-发酵技术。业内专家认为,用酶替代硫酸水解是纤维素乙醇生产的发展方向。目前已经和准备进行示范装置试验的纤维素生物汽油生产技术包括快速热解-加氢改质技术和BioForming技术。第二代生物柴油主要以动植物油脂为原料,通过催化加氢生产非脂肪酸甲酯生物柴油,它是理想的优质柴油调合组分。生产第二代生物柴油的加氢技术包括加氢脱氧、回收丙烷和其他轻烃气体、脱水、异构化和裂化、蒸馏等5个步骤,主要有NExBTL可再生柴油生产技术、Ecofining绿色柴油生产技术、Haldor Topsoe可再生柴油生产技术、EERC可再生柴油生产技术。第三代生物燃料有两种:一种是以海藻油为原料生产乙醇、丁醇、喷气燃料和柴油,海藻培养(生长)和萃取海藻油是核心步骤,目前尚处于初期阶段;另一种是以生物质原料通过气化合成生产汽油、喷气燃料和柴油,重点是开发生物质气化技术,降低生产成本。我国应借鉴国外发展第二代和第三代生物燃料的做法,把技术开发工作做深做细做透,搞清楚原料的供应情况;目前我国生物柴油主要采用酯交换法生产脂肪酸甲酯,应考虑开发和采用加氢法生产第二代生物柴油,并努力扩大除麻风果油以外的原料来源;同时应加大海藻生物燃料和生物质气化合成生物燃料的开发力度。     

生物质富氧气化气作为机动车燃料的初步试验

试验研究了生物质气化产出气作为机动车燃料的可行性.在实际运行的生物质气化系统中进行了富氧试验,并将生物质富氧气化产出气作为机动车燃料,进行了行驶试验.分析了富氧气化剂对于气化产出气成分的影响,对生物质气化产出气作为机动车燃料的经济可行性进行了简单分析.结果表明,采用富氧气化剂可以明显提高产出气的热值,增加气体的能量密度,同时,产出气作为燃料能够满足机动车的动力性要求;在生物质原料成本控制在一定范围内的情况下,生物质气化产出气作为汽车燃料能够体现一定的经济性.     

Biomass-based energy fuel through biochemical routes: A review

Energy demand is increasing continuously due to rapid growth in population and industrialization development. The development of energy sources is not keeping pace with spiraling consumption. Even developed countries are not able to compensate even after increasing the energy production multifold. The major energy demand is provided from the conventional energy sources such as coal, oil, natural gas, etc. Two major problems, which every country is facing with these conventional fuels, are depletion of fossil fuels and deterioration of environment.The present review article aims to highlight various biochemical processes for conversion of biomass into biological hydrogen gas and ethanol. The present discussion focuses on hydrogen production through various routes viz. fermentative, photosynthesis and biological water gas shift reaction. In addition, emphasis has been laid on ethanol as biomass-based energy fuel. The discussion has been focused on the technology for ethanol production from various biomass sources such as molasses, lignocellulosic feedstock and starch. Various biochemical processes and their major steps involved during the ethanol production from biomass have been discussed in detail.     

生物质气化气中焦油非催化裂解实验研究

生物质气化是一种环境友好的新能源利用技术,焦油作为生物质气化的副产物,是限制气化技术发展的主要因素.试验针对生物质气化产出气中焦油在700～1 000℃裂解温度区间的裂解特性进行了分析,并提出了焦油裂解产气率的概念.试验表明,焦油裂解气可以成为生物质气化气的有效的能量补充,而且随着裂解温度的升高,焦油裂解产气率增加,焦...     

Tar property,analysis, reforming mechanism and model for biomass gasification—An overview

Biomass becomes an important primary energy source as well as renewable energy source. As the most promising biomass utilization method, biomass gasification is gaining attention as a route for biomass energy production, but producer gas from this process usually contains unacceptable levels of tar. The tar control and convert is a key issue for a successful application of biomass-derived producer gas. A detail overview on tar chemical and physical properties, reforming mechanism and reaction kinetic model are summarized in this paper.     

Production of hydrogen energy through biomass (waste wood) gasification

Biomass gasification, conversion of solid carbonaceous fuel into combustible gas by partial combustion, is a prominent technology for the production of hydrogen from biomass. The concentration of hydrogen in the gas generated from gasification depends mainly upon moisture content, type and composition of biomass, operating conditions and configuration of the biomass gasifier. The potential of production of hydrogen from wood waste by applying downdraft gasification technology is investigated. An experimental study is carried out using an Imbert downdraft biomass gasifier covering a wide range of operating parameters. The producer gas generated in the downdraft gasifier is analyzed using a gas chromatograph (NUCON 5765) with thermal conductivity detector (TCD). The effects of air flow rate and moisture content on the quality of producer gas are studied by performing experiments. The performance of the biomass gasifier is evaluated in terms of equivalence ratio, composition of producer gas, and rate of hydrogen production.     

Optimal location of lignocellulosic ethanol refineries with polygeneration in Sweden

The integration of ethanol production with combined heat and power plants is considered in this paper. An energy balance process model has been used to generate data for the production of ethanol, electricity, heat and biogas. The geographical position of such plants becomes of importance when using local biomass and delivering transportation fuel and heat. An optimization model has thus been used to determine the optimal locations for such plants in Sweden. The entire energy supply and demand chain from biomass outtake to gas stations filling is included in the optimization. Input parameters have been studied for their influence on both the final ethanol cost and the optimal locations of the plants. The results show that the biomass cost, biomass availability and district heating price are crucial for the positioning of the plant and the ethanol to be competitive against imported ethanol. The optimal location to set up polygeneration plants is demonstrated to be in areas where the biomass cost is competitive and in the vicinity of small to medium size cities. Carbon tax does not influence the ethanol cost, but solicits the production of ethanol in Sweden, and changes thus the geography of the plant locations.     

Gasification of lignocellulosic biomass in fluidized beds for renewable energy development: A review

A literature review on gasification of lignocellulosic biomass in various types of fluidized bed gasifiers is presented. The effect of several process parameters such as catalytic bed material, bed temperature and gasifying agent on the performance of the gasifier and quality of the producer gas is discussed. Based on the priorities of researchers, the optimum values of various desired outputs in the gasification process including improved producer gas composition, enhanced LHV, less tar and char content, high gas yield and enhanced carbon conversion and cold gas efficiency have been reported. The characteristics and performance of different fluidized bed gasifiers were assessed and the obtained results from the literature have been extensively reviewed. Survey of literature revealed that several industrial biomass gasification plants using fluidized beds are currently conducting in various countries. However, more research and development of technology should be devoted to this field to enhance the economical feasibility of this process for future exploitations.     

Biomass conversion into fuel gas using circulating fluidised bed technology: the concept improvement and modelling discussion

Fuel gas production from biomass using circulating fluidised bed technology is presented in our laboratory. This improved technical concept is aiming at producing high quality gas, in terms of low tar level and particulates carried out in the fuel gas, and overall emissions’ reduction associated with fuel gas combustion, as well as stable and reliable operation with the minimum fluctuations in the producer gas volume and composition. Based on this concept, a characteristic theoretical modelling approach involving hydrodynamics, chemical reaction kinetics, and energy balance is accordingly discussed. In addition, very preliminary experimental results from a laboratory-made test rig are also given.     

Recent advances in hydrogen production by thermo-catalytic conversion of biomass

Hydrogen production from biomass is a green, clean, and zero emissions technology that has attracted increasing attention. This technology has been considered to possess a long-term growth potential, and it is expected to gradually reduce environmental pollution and over-exploitation of resources. In this context, we holistically review this technology and focused on the conversion of biomass into hydrogen using chemical methods (i.e., those with potential for obtaining H₂-rich producer gas streams). Several reaction parameters were discussed and classified herein including biomass conversion methods and conditions, hydrogen production and carbon conversion ratios, the effect of different catalysts types, the catalytic properties of these materials, and their related mechanisms. The overall findings provide new insights for the selection of highly effective and suitable hydrogen production catalysts by biomass conversion applications.     

First and second law thermodynamic analysis of a single and dual-stage ignition biomass downdraft gasifier

The dual-stage ignition biomass downdraft gasifier is an enormous tar reduction technology as against a single-stage ignition biomass gasification. Exergetic analysis of the system guides toward a possible performance enhancement. In dual-stage gasification, around 67.76% of input exergy is destructed in the several components, while 9.16% is obtained as a useful exergy output and 24.34% is found to be as a useful energy output there. The entire unit was assessed with a progressively rising electric load from 15.24 kW to 38.86 kW. The enhanced producer gas quality comes from 57% combustible gas with a higher heating value of 6.524 MJ/Nm³ and tar content of 7 mg/Nm³ after the paper filter, whereas the biomass consumption rate is 58 kg/h at the greatest load with the grate temperature of 1310–1370 °C. The samples of exhaust gas emissions are obtained environmentally favorable. The results even described that the dual-stage ignition biomass downdraft gasifier has significantly greater energetic and exergetic efficiency as compared to the single-stage gasifier.