生物质富氧气化特性的研究

富氧气化是先进的中热值气化方法之一，具有设备体积小，运行稳定等优点。从富氧气化的原理出发，分析氧气浓度，气化当量比等因素对气化结果的影响，并在实验的基础上，分析讨论提高了富氧气化经济性和实用性的途径，总结得到的循环流化床富氧气化的最佳运行条件：氧气浓度，气化当量比约０．１５。     

生物质富氧气化产气特性的实验研究与灰色关联分析

在小型上吸式固定床气化炉内对典型生物质进行富氧气化试验，分析了试验物料、气化温度和氧气流量对气化产气特性的影响。实验研究表明，物料含可燃质多时，产气品位高；随着气化温度的升高，产气中可燃气含量增加；氧气流量增加后，产气热值出现最大值。通过灰色关联分析发现，物料性质和气化温度是影响产气特性的主要因素。     

生物质膜法富氧气化制气技术试验研究

利用膜法富氧制气与生物质热解气化技术相结合,在半工业试验的基础上,通过改变固定床气化试验台中的氧浓度等关键反应因素,研究子玉米秸秆在常压固定床气化炉中的气化特性,并总结出燃气热值及燃气主要成分随氧气浓度变化的主要规律.试验研究表明,膜法富氧气化技术是可行的,对改善生物质燃气组分和热值具有较好作用,可用于工程实践.     

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.     

固体废物富氧气化产气特性与灰色关联分析

在小型上吸式固定气化炉上对典型固体废弃物进行富氧气化实验，依据多个实验分析了实验物料、气化温度和氧气流量变化时对气化产气特性的影响。研究表明，物料含可燃质高时，产气品位也好；随着气化温度的升高，产气中可燃气含量增加，物料的反应活性增大；氧气流量增加后，物料的反应活性增大，产气热值有最大值。为了探讨影响产气特性的各因素作用程度大小，使用灰色关联知识分析发现，相对来说物料性质和气化温度是比较重要的影响因素。     

生物质流化床富氧气化过程热平衡模型

基于元素守恒、化学反应平衡和能量守恒,考虑碳不完全转化因素,建立生物质流化床富氧气化的热平衡模型。采用非平衡当量因子对气化反应平衡常数进行修正,修正后的模拟数据与文献数据吻合良好。利用该模型模拟富氧浓度和原料含水率对气体组分、气体热值和气化效率的影响。模拟工况下的结果表明:富氧浓度从21%增至100%,可燃组分含量增多,气体热值从6.37 MJ/m~3增至11.44 MJ/m~3,气化效率不断增大;原料含水率从零增至35%,气化炉温不断降低,可燃组分减少,气体热值从5.45 MJ/m~3降至4.65 MJ/m~3。     

鼓泡流化床生物质富氧气化中试试验研究

以鼓泡流化床为中试反应装置、木屑为原料,试验研究布风板开孔率、床料粒径、床料高度、最小流化速度以及气化介质等对气化结果的影响。结果表明:孔径和开孔率分别为Ф2 mm和0.50%的布风板布风效果较好;床料粒径为0.18~0.25 mm的石英砂,床料高度为140 mm时床内流化效果较理想;最小流化速度受床料粒径和升温速率影响;初步试验测得,富氧气化比例为50%时热值可达9.6 MJ/m~3。     

生物质流态化催化气化技术工程化研究

在研究开发的内循环锥形流态化气化炉内。对稻草、麦草等软秸秆物料粉碎后，或者直接使用木屑等细粉状原料，进行了热解气化和催化气化的工程化应用试验研究。研究结果表明：气化反应在600—820℃的一个较宽温度范围内，均能稳定连续运行。麦草原料气化所产生的煤气热值比稻草和稻壳都高，其热值可达7716kJ／m^3。木屑气化所产生煤气热值最高则达9064kJ／m^3，远远高于一般生物质气化煤气。对流化床气化来讲，即使在非催化气化条件下，其气化产生的煤气热值比采用下吸式气化炉产生的煤气热值提高40%左右，并且气化温度较固定床(上吸式、下吸式)气化炉低。同时进行的催化气化试验发现，催化剂CaO能明显提高煤气热值、降低CO组分，Na2CO3催化气化能提高气体H2的含量。在800℃试验时，添加催化剂能明显提高气体的热值。     

以蒸汽为气化剂的生物质干馏与完全气化(sBG)技术的中试研究

描述了固定床生物质气化技术中采用蒸汽做气化剂的工业化中间试验情况。试验结果表明，采用该技术的装置具有操作方便、气体热值高、产气率适中等特点，是广大城镇、乡村利用当地资源，实现中、小规模燃气集中供应的经济适用的气源设备。     

下吸式生物质气化炉热力学平衡模型研究

建立下吸式生物质气化炉热力学平衡模型,该模型包括焦炭、焦油和气体,并用已公布的实验数据对模型进行验证,均方根（RMS）在1.304~3.814之间,结果表明该模型的预测值与实验数据吻合较好,可认为模型可靠。然后模拟棉秆在下吸式生物质气化炉中以空气和富氧气体2种气化氛围下,不同操作参数(当量比、预热温度和气化炉反应温度)下对棉秆气化的气体组分、热值和产率的影响。模拟结果表明：富氧气体为气化剂时,当量比从0.20增至0.35时,气体中N₂含量比空气显著下降,达10%以上,同时发现能提高气体中H₂和CO的含量和热值,热值比空气提高约20%。预热温度对气化成分变化影响有限,随预热温度从30 ℃变化到130 ℃,气体的平均热值从空气的5.2 MJ/m³提高到富氧气体的7.0 MJ/m³。随气化炉内反应温度从750 ℃升至1250 ℃,空气和富氧气体2种气化剂下的H₂和CO分别从20.94%、26.84%和21.77%、28.67%下降到4.06%、9.12%和10.49%、21.60%,导致气体的热值降低。     

Hydrogen-rich gas production from biomass air and oxygen/steam gasification in a downdraft gasifier

Biomass gasification is an important method to obtain renewable hydrogen. However, this technology still stagnates in a laboratory scale because of its high-energy consumption. In order to get maximum hydrogen yield and decrease energy consumption, this study applies a self-heated downdraft gasifier as the reactor and uses char as the catalyst to study the characteristics of hydrogen production from biomass gasification. Air and oxygen/steam are utilized as the gasifying agents. The experimental results indicate that compared to biomass air gasification, biomass oxygen/steam gasification improves hydrogen yield depending on the volume of downdraft gasifier, and also nearly doubles the heating value of fuel gas. The maximum lower heating value of fuel gas reaches 11.11 MJ/N m³ for biomass oxygen/steam gasification. Over the ranges of operating conditions examined, the maximum hydrogen yield reaches 45.16 g H₂/kg biomass. For biomass oxygen/steam gasification, the content of H₂ and CO reaches 63.27–72.56%, while the content of H₂ and CO gets to 52.19–63.31% for biomass air gasification. The ratio of H₂/CO for biomass oxygen/steam gasification reaches 0.70–0.90, which is lower than that of biomass air gasification, 1.06–1.27. The experimental and comparison results prove that biomass oxygen/steam gasification in a downdraft gasifier is an effective, relatively low energy consumption technology for hydrogen-rich gas production.     

Thermodynamic methodology to support the selection of feedstocks for decentralised downdraft gasification power plants

Thermodynamic criteria as a feedstock selection tool for decentralised downdraft gasifiers coupled to spark-ignition engines are presented in this work. The methodology consists of an energy and exergy analysis of gasification process. The analysis is carried out by computational modelling of the gasification process as a function of biomass type (ultimate analysis, moisture content and heating value) and fuel/air ratio. Considering a system operating with different wood species, analysed parameters are gas heating value, energy and exergy efficiencies and engine fuel quality (EFQ). With a fixed fuel/air ratio (2.6) and moisture content (20%wt), it is highlighted that as the carbon-oxygen molar ratio of wood decreases from 2.0 to 1.78 as model input, reaction temperature increases by 9%, energy and exergy efficiencies diminish by 1.8% and 4.2%, respectively, while EFQ increases by 3.2%. Therefore, for decentralised power plants, biomass should be selected to produce higher EFQ.     

Main routes for the thermo-conversion of biomass into fuels and chemicals. Part 1: Pyrolysis systems

Since the energy crises of the 1970s, many countries have become interest in biomass as a fuel source to expand the development of domestic and renewable energy sources and reduce the environmental impacts of energy production. Biomass is used to meet a variety of energy needs, including generating electricity, heating homes, fueling vehicles and providing process heat for industrial facilities. The methods available for energy production from biomass can be divided into two main categories: thermo-chemical and biological conversion routes. There are several thermo-chemical routes for biomass-based energy production, such as direct combustion, liquefaction, pyrolysis, supercritical water extraction, gasification, air–steam gasification and so on. The pyrolysis is thermal degradation of biomass by heat in the absence of oxygen, which results in the production of charcoal (solid), bio-oil (liquid), and fuel gas products. Pyrolysis liquid is referred to in the literature by terms such as pyrolysis oil, bio-oil, bio-crude oil, bio-fuel oil, wood liquid, wood oil, liquid smoke, wood distillates, pyroligneous tar, and pyroligneous acid. Bio-oil can be used as a fuel in boilers, diesel engines or gas turbines for heat and electricity generation.     

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.     

Results with a bench scale downdraft biomass gasifier for agricultural and forestry residues

A small scale fixed bed downdraft gasifier system to be fed with agricultural and forestry residues has been designed and constructed. The downdraft gasifier has four consecutive reaction zones from the top to the bottom, namely drying, pyrolysis, oxidation and reduction zones. Both the biomass fuel and the gases move in the same direction. A throat has been incorporated into the design to achieve gasification with lower tar production. The experimental system consists of the downdraft gasifier and the gas cleaning unit made up by a cyclone, a scrubber and a filter box. A pilot burner is utilized for initial ignition of the biomass fuel. The product gases are combusted in the flare built up as part of the gasification system. The gasification medium is air. The air to fuel ratio is adjusted to produce a gas with acceptably high heating value and low pollutants. Within this frame, different types of biomass, namely wood chips, barks, olive pomace and hazelnut shells are to be processed. The developed downdraft gasifier appears to handle the investigated biomass sources in a technically and environmentally feasible manner. This paper summarizes selected design related issues along with the results obtained with wood chips and hazelnut shells.     

生物质富氧——水蒸气气化制氢特性研究

以一个鼓泡流化床为反应器,对生物质富氧—水蒸气气化制取富氢燃气的特性进行了一系列的实验研究。通过对试验数据的分析,探讨了主要参数温度、水蒸气/生物质(S/B)和氧浓度对气体成分、氢产率和潜在产氢量的影响。结果表明:在3个主要参数的变化范围内,氢产率和潜在氢产量受温度的影响最大:当温度从700~900℃时,每千克生物质氢产量从18g增加到了53g,每千克生物质潜在氢产量从71.6g增加到了115.6g。     

An experimental study on air gasification of biomass micron fuel (BMF) in a cyclone gasifier

Biomass micron fuel (BMF) produced from feedstock (energy crops, agricultural wastes, forestry residues and so on) through an efficient crushing process is a kind of powdery biomass fuel with particle size of less than 250 μm. Based on the properties of BMF, a cyclone gasifier concept has been considered in our laboratory for biomass gasification. The concept combines and integrates partial oxidation, fast pyrolysis, gasification, and tar cracking, as well as a shift reaction, with the purpose of producing a high quality of gas. In this paper, characteristics of BMF air gasification were studied in the gasifier. Without outer heat energy input, the whole process is supplied with energy produced by partial combustion of BMF in the gasifier using a hypostoichiometric amount of air. The effects of equivalence ratio (ER) and biomass particle size on gasification temperature, gas composition, gas yield, low-heating value (LHV), carbon conversion and gasification efficiency were studied. The results showed that higher ER led to higher gasification temperature and contributed to high H₂-content, but too high ER lowered fuel gas content and degraded fuel gas quality. A smaller particle was more favorable for higher gas yield, LHV, carbon conversion and gasification efficiency. And the BMF air gasification in the cyclone gasifier with the energy self-sufficiency is reliable.     

An advanced integrated biomass gasification and molten fuel cell power system

Biomass has recently received considerable attention as a potential substitute for fossil fuels in electric power production. Renewable biomass crops, industrial wood residues, and municipal wastes as fuels for production of electricity allow substantial reduction of environmental impact. High reactivity of biomass makes it relatively easy to convert solid feedstocks into gaseous fuel for subsequent use in a power cycle.So far most of the studies were focused on investigating performance and economics of biomass gasifiction–gas turbine systems. A general conclusion resulting from these studies is that the combination of biomass gasifiers, hot gas cleanup systems, and advanced gas turbines is promising for cost competitive electric power generation[1, 2]. In this paper another concept of biomass fueled power systems is considered, namely biomass gasification with a molten carbonate fuel cell (MCFC). Comparison between two concepts is made in terms of efficiency, feasibility, and process requirements. As an example of such a system, a highly efficient novel power cycle consisting of the Battelle gasification process, a molten carbonate fuel cell, and a steam turbine is introduced. The calculated efficiency is around 53%, which exceeds efficiencies of traditional designs[1, 3] considerably. Finally, an economic analysis and electricity cost projection are performed for a power plant consuming 2000 tons of biomass per day. Results are compared with those for more traditional integrated biomass gasification/gas turbine systems and for coal fueled cycles.