河北省生物质固体成型燃料产业发展研究

随着国家城乡一体化建设的推进,能源需求量将急剧增加。生物质固体成型燃料作为重要的可再生能源,可直接用于居民炊事采暖、区域供热和工农业生产。发展生物质固体成型燃料产业,有助于实现能源、环境和经济社会的综合效益。利用好河北省的资源、技术等优势,制定科学的政策措施,将加快河北省生物质固体成型燃料产业的规模化、市场化发展。     

Development of energy and emission parameters for densified form of lignocellulosic biomass

The environmental performance of production and distribution of densified form of lignocellulosic biomass (i.e., agri-residue based pellets) in Western Canada in terms of energy and greenhouse gas (GHG) emission was assessed. The results show that energy usage and resulted emissions are highest in field activities especially if emission and energy are attributed to straw in farming stage where nitrogen fertilizer is the highest contributor. Significant reduction of energy use (64%) and emission (65%) are possible if the organic fertilizer is used in farming. Adopting the zero tillage option instead of conventional practice results in energy saving (10%) and emission reduction (8%). From the scenario analyses it is also evident that using biomass as an energy source during drying or no drying in pellet production stage or using alternate mode (i.e., truck and train) of transport for pellet delivery result in less than 5% reduction of the energy use and emissions compared to the base case. Agri-pellet has the potential to offset substantial amount of GHG emission compared to other fuel sources including wood pellets. The energy and emission of production chain of agri-pellets may vary between countries but overall trend compared to other fuel sources would be similar.     

生物质成型燃料致密成型机理及品质评价指标

利用机械力将生物质压缩或挤压成为体积密度较大、热效率较高、便于运输储藏的固体成型燃料,是生物质能源化利用最简单、最直接的途径之一。文章对生物质成型燃料的致密成型机理做出较为全面的探讨,并介绍了目前国外对生物质成型燃料品质评价的指标和部分西方发达国家生物质成型燃料标准规范,为加快我国生物质成型燃料技术的发展和标准规范的制定提供理论依据和技术参考。     

生物质固化成型燃料引火助燃剂的试验研究

对生物质固化成型燃料(Densified biomass briquette fuel,DBBF)引火助燃剂进行了试验研究。以LLA-6型户用生物质炉具为试验装置,选取3种废弃液体燃料为原料,按不同的体积比制成15种液体引火助燃剂,对助燃剂的不同用量进行了试验研究。结果表明,助燃剂JC15和CJ51均能在1min内顺利将DBBF引燃,在助燃剂JC15用量为8～9mL时,40s即可使炉火达到炊事要求,大大缩短了不加助燃剂时燃料的引燃时间。引火助燃剂的研究解决了DBBF点火难和使用不方便的问题,为DBBF的大规模推广提供了前提保障。     

我国生物质固体成型燃料CDM项目开发前景分析

生物质能领域是我国开展CDM项目的重点领域之一,而生物质固体成型燃料技术又是生物质能主要利用技术之一,但目前我国尚未有在EB成功注册的生物质固体成型燃料CDM项目。文章以农业部示范项目为例,分析了我国生物质固体成型燃料产业发展现状、开发CDM项目的可行性、适用方法学及开发潜力,认为在我国开发生物质固体成型燃料CDM项目是可行的并具有较好的开发前景,建议开发专门的小规模方法学用于指导该领域CDM项目的开发,促进其产业化发展。     

Factors affecting nonindustrial private forest landowners' willingness to supply woody biomass for bioenergy

Bioenergy is a renewable form of potential alternative to traditional fossil fuels that has come to the forefront as a result of recent concerns over high price of fuels, national security, and climate change. Nonindustrial private forest (NIPF) landowners form the dominant forest ownership group in the southern United States. These forests often tend to have large quantities of small diameter trees. Use of logging residues and non-marketable small diameter trees for bioenergy production can create economic opportunities for NIPF landowners. The results demonstrated that landowners’ willingness to harvest woody biomass was influenced by their ownership objectives, size of the forest, structure and composition of tree species, and demographic characteristics. The model found that relatively younger landowners who owned large acres of forestland with pine plantations or mix forests had the potential to become a preferable choice for contractors, extension foresters and bioenergy industries as they were more likely to supply woody biomass for bioenergy. Findings of this study will be useful to bioenergy industries, extension foresters, nonindustrial private forest landowners and policy makers.     

Physical characterisation and chemical composition of densified biomass fuels with regard to their combustion behaviour

With respect to the use of densified biomass fuels in fully automatic heating systems for the residential sector a high quality of these fuels is required. Several European countries already have implemented standards for such fuels. In other countries such standards are in preparation or planned. Furthermore, in some countries also standards from associations are existing (e.g. from the Austrian Pellets Association). In addition to these national standards, European standards for solid biomass fuels are under development. For producers of densified biomass fuels, especially for pellet producers, it is therefore very important to produce high-quality fuels keeping the limiting values of the standards addressed. However, in this context it has to be considered that as a high fuel quality as is necessary for the combustion of densified biomass fuels in automatic small-scale furnaces is not necessary if these fuels are used in larger industrial furnaces as they are equipped with more sophisticated flue gas cleaning, combustion and process control systems. Two pellet qualities, one for industrial and one for small-scale consumers seem to be more meaningful.

Within the framework of the EU-ALTENER-project “An Integrated European Market for Densified Biomass Fuels (INDEBIF)” a questionnaire survey of European producers of densified biomass fuels was performed. In this connection the possibility was offered to the producers to participate in an analysis programme with their fuels. An overview was obtained of the qualities of densified biomass fuels offered in the European market, covering pellets and briquettes from Austria, Italy, Sweden, Spain, Norway and the Czech Republic.

The parameters analysed were the dimensions of the fuels, the bulk and the particle density, the water and the ash content, the gross and the net calorific value, the abrasion, the content of starch (as an indication for the use of biological binding agents), the concentrations of C, H, N, S, Cl, K as well as of the heavy metals Cd, Pb, Zn, Cr, Cu, As and Hg. These parameters have been chosen following the Austrian, German, Swiss and Swedish standards for densified biomass fuels.

The results showed that a majority of the participating producers produce fuels of high quality. However, wood pellets of some producers show a high abrasion, one of the most important quality parameters for pellets. An increased amount of fines often causes failures in the feeding systems used in the residential heating sector. In order to decrease abrasion, the addition of small amounts of biological binding agents (e.g. maize or rye) is possible. This kind of additive is most common in Austria.

Moreover, some producers obviously use not only chemically untreated raw materials or additives, which increase the content of pollutants. Such fuels cause problems regarding emissions, deposit formation and corrosion. Emission problems are expected due to increased contents of N, Cl, S as well as heavy metals. Increased concentrations of heavy metals additionally contaminate the ash, increased Cl concentrations raise the risk of corrosion. Moreover, an increased content of K has a negative effect on the ash melting behaviour and causes higher aerosol formation, which enhances deposit formation and particulate emissions.     

Characterization and prediction of biomass pyrolysis products

In this study some literature data on the pyrolysis characteristics of biomass under inert atmosphere were structured and analyzed, constituting a guide to the conversion behavior of a fuel particle within the temperature range of 200-1000 °C. Data is presented for both pyrolytic product distribution (yields of char, total liquids, water, total gas and individual gas species) and properties (elemental composition and heating value) showing clear dependencies on peak temperature. Empirical relationships are derived from the collected data, over a wide range of pyrolysis conditions and considering a variety of fuels, including relations between the yields of gas-phase volatiles and thermochemical properties of char, tar and gas. An empirical model for the stoichiometry of biomass pyrolysis is presented, where empirical parameters are introduced to close the conservation equations describing the process. The composition of pyrolytic volatiles is described by means of a relevant number of species: H₂O, tar, CO₂, CO, H₂, CH₄ and other light hydrocarbons. The model is here primarily used as a tool in the analysis of the general trends of biomass pyrolysis, enabling also to verify the consistency of the collected data. Comparison of model results with the literature data shows that the information on product properties is well correlated with the one on product distribution. The prediction capability of the model is briefly addressed, with the results showing that the yields of volatiles released from a specific biomass are predicted with a reasonable accuracy. Particle models of the type presented in this study can be useful as a submodel in comprehensive reactor models simulating pyrolysis, gasification or combustion processes.     

生物质及其热裂解产物生物油的特性分析

以红松、白松、落叶松、玉米秸秆等不同生物质为原料,对流化床反应器热裂解制取的生物油进行了研究试验,通过对生物油的物理特性及其成分的分析,得出的实验结果表明:红松制取的生物油品质最好,热值高,含水率低,更适合进一步改性研究和应用,并利用现代精密仪器GC-MS对生物油进行了组分分析,解释了生物油高含氧和高含水特性。     

生物质燃烧的气体产物及动力学分析

采用热重分析法对3种生物质样品进行燃烧特性试验,并利用质谱仪在线监测了燃烧排放的部分气体成分.对生物质样品进行燃烧反应动力学分析,得到相关的表观活化能及指前因子.研究结果表明:燃烧过程可以分为3个温度阶段:①吸附水的析出及铵盐的热分解(室温～150℃);②半纤维素、纤维素及部分木质素的热解(150～350℃);③木质素的热解及焦炭的燃烧(350～600℃).利用质谱仪在线监测了CH4,NH3,H2O,CO2,NOx等气体产物,其质谱曲线与对应的热重曲线相符合,也验证了各反应阶段的假设.     

Manufacturing gaseous products by pyrolysis of microalgal biomass

Algal biomass is considered as an alternative raw material for biofuel production. The search for new types of raw materials including high-energy types of microalgae remains relevant, since the share of motor fuels in the world energy balance remains consistently high (about 35%) with the oil price characterized by high volatility. The authors have considered the advantages of microalgae as raw materials for fuel production. Biochemical and thermochemical conversion are proposed as technologies for their processing. The paper presents the results of the study on the pyrolysis of the biomass of the blue-green microalgae/cyanobacterium Arthrospira platensis rsemsu 1/02-P clonal culture from the collection of the Research Laboratory of Renewable Energy Sources of the Lomonosov Moscow State University. The experimental investigation on the pyrolysis process of microalgal biomass has been carried out with the experimental setup made at the Institute of High Temperatures RAS in pure nitrogen 6.0 to create an oxygen-free medium with a linear heating rate of 10°С/min from room temperature to 1,000°С. The entire pyrolysis process has proceeded in the endothermic region. The specific values for solid residue, pyrolysis liquid and gaseous products have been experimentally determined. The following products have been manufactured by pyrolysis of microalgal biomass weighing 15 g: 1) char with a solid residue mass of 2.68 g, or 17.7% of MAB initial mass (while 9.3% of MAB initial mass has remained in the reactor); 2) pyrolysis liquid with a mass of 3.3 g, or 21.9% of initial mass; 3) noncondensable pyrolysis gases, 1.15 L. The specific volumetric gas yield (amount of gas released from 1 kg of RM) has amounted to 0.076 nm³/kg.In the paper, the analysis of the composition and specific volumetric yield of non-condensable pyrolysis gases produced in the pyrolysis process depending on temperature has been carried out. It is shown that the proportion of high-calorific components of the gas mixture (hydrogen, methane and carbon monoxide) increases with the temperature increase. The heating value assessment for the mixture of these gases has been performed as well.     

桉树类生物质热解及产物释放特性研究

采用热重红外联用方法研究不同升温速率下桉树枝和桉树皮的热解特性和热解气体产物的释放特性,对比分析两者的差异性及差异机理。结果表明:桉树枝热解过程主要分为干燥、热解和碳化3个阶段,热解速率较快,气体产物释放主要集中在热解阶段进行,主要气体产物有烷烃、醇、酚、醛、羧酸、酮等多种有机气体产物和少量CO,CO2;桉树皮热解过程分为干燥、进一步干燥、热解反应、碳化及高温持续碳化5个阶段,相比桉树枝热解速率明显较低。桉树皮热解反应阶段在450⁵50℃和650550℃和650⁸00℃两个高温区间存在较为剧烈的碳化反应过程,主要气体产物为CO2和CO。     

木质生物质直接液化产物的红外光谱分析

用傅立叶变换红外光谱法对木质生物质在280—380℃水中的直接液化产物进行了研究。研究表明。木质生物质的液化可以分为2个阶段,即纤维素类和木质素类的液化;最终液化产物官能团受温度的影响不大;最终液化产物是复杂的混合物,含有烃、醛、酮、酚和酯等各类化合物。     

Influence of temperature on organic structure of biomass pyrolysis products

Biomass pyrolysis experiments were performed in a tubular reactor at different temperatures, the effects of which on organic structure of semi-char and tar had been investigated. Fourier-transform infrared (FTIR) analysis was conducted by a Nicolet 6700 FTIR spectrometer. The tar components at different temperatures were analyzed by GC/MS. It was observed that pyrolysis of biomass mainly occurs in the temperature range of 300–600 °C. A high temperature favored the production of gases. The yield of semi-char and the contained organic functional groups(CO, CC, C–H, C–O and OH) decreases significantly with the increasing final temperature. The tar yield passes through a maximum at about 500 °C. The organic functional groups in tar were stable but the transmittance of these groups decreased with the increasing final temperature.     

Medium-temperature conversion of biomass and wastes into liquid products,a review

The subject of this review is the production of new-generation biofuels and fuels from wastes by cost effective medium temperature conversion processes. Recent literature results concerning pyrolysis at medium-temperature (mainly 300–450 °C) of biomasses, plastics and wastes are reviewed. The focus is on processes usable to maximize the production of liquids. Conclusions concern the relation of raw material composition and reaction temperature on the quality and quantity of liquid products. The main limitation of this approach is the high heteroatom content that is frequently present in the resulting fuels, particularly oxygen from biomass-derived fuels, but also nitrogen, sulphur and chlorine from waste derived fuels. For this reason, further refining treatment could be necessary, depending on the use of the resulting fuel.     

High-temperature air and steam gasification of densified biofuels

An experimental study was carried out to investigate gasification of densified biofuels using highly preheated air and steam as a gasifying agent. Preheat of air and steam is realised by means of the newly developed high-cycle regenerative air/steam preheater. Use of highly preheated feed gas provides additional energy into the gasification process, which enhances the thermal decomposition of the gasified solids. For the same type of feedstock the operating parameters, temperature, composition and amount of gasifying agent, were varied over a wide range. Results of experiments conducted in a high-temperature air/steam fixed bed updraft gasifier show the capability of this technology of maximising the gaseous product yield as a result of the high heating rates involved, and the efficient tar reduction. Increase of the feed gas temperature reduces production of tars, soot and char residue as well as increases heating value of the dry fuel gas produced. Overall, it has been seen that the yield and the lower heating value of the dry fuel gas increase with increasing temperature.     

Factors affecting small axial cooling fan performance

Many factors such as outer diameter,hub ratio,blade numbers,shape and stagger angle affect the performance of small cooling fans.A small cooling fan was simulated using CFD software for three blade stagger angles (30.5°,37.5°,44.5°)and obtained the internal flow field and the static characteristics.Research indicated that the stagger angle has an obvious effect on the static characteristics of a fan.For flow rates below 0.0104 m3/s,total pressure is the greatest when the stagger angle is 37.5°;flow rates higher than 0.0104 m3/s,the total pressure is greatest when the stagger angle is 44.5° For the same flow rates,the velocity at inlet of pressure surface increases with increasing stagger angle,but the change of velocity on the suction surface is very small.For one model,vortices and the speed of revolution surfaces decrease with tip clearance increasing.But for other three models,increasing the stagger angle,the vortex intensity and speed of revolution surfaces at same height tip clearance increases,simultaneously,the position of vortex offset from the top of the rotor blade to the suction surface.     

Factors affecting emissions from diesel fuel and water-in-diesel emulsion

The purpose of this research is to investigate the effect of addition of surfactant and water in diesel and to make an emulsified fuel considering the needs for vehicle performance and its cleanest possible operation. The total surfactant concentration in each of the diesel-water emulsion samples studied (span 20, span 80, tween 20, tween 80) is fixed at 1% w/w. The water content is variable at 5–15% w/w and the diesel content is varied from 84 to 94% w/w. Among all the tested nonionic surfactants, tween 80 is found to prominently reduce the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) emissions. Tween 20 reduced the NOx emission to a greater extent. Diesel emulsion with a fixed ratio of span 80 and tween 80 (1:1) efficiently reduced the overall emissions as compared to diesel alone. The developed diesel emulsion employed with nonionic surfactants clearly reduced the harmful engine emissions such as CO, HC, and NOx, signifying them as a future potential emulsifier in diesel fuel emulsion.     

砂石混合体的导热性能影响因素分析

为了分析地应力等因素对岩土体热力学性质的影响机理,课题组对大型直剪仪进行了改装,并在试样室内安装了加热系统、热流密度传感器、测温系统,组建了能对大颗粒砂石混合体导热系数进行测定的试验装置。基于稳态热平板法原理,利用该试验装置进行了干燥砂土导热系数的测定,并与基于瞬态法原理的DRE-III多功能快速导热测试仪的测定结果进行对比,验证了该试验装置的可靠性。在此基础上,利用改装的试验装置对不同固结压力、不同含石率条件下含有大颗粒粒径的砂石混合体进行了导热系数的测量试验。分析结果表明,增加含石率可以改善砂石混合体颗粒间的接触情况,施加固结压力后砂石混合体的干密度得到了提升,砂石混合体的导热系数随着含石率和固结压力的增大而增大。文章还利用DRE-III多功能快速导热测试仪对不同含水率情况下砂石混合体的导热系数进行测定,得出低含水率时随着含水率的增大砂石混合体的导热系数增幅明显。文章的研究结果为浅层地热开发中地埋管的设计与施工提供了重要的参考。