木质能源的开发与经济社会的可持续发展

自古以来,木质能源就是人类使用的基本能源,随着化石能源的日益短缺和生物质能转化技术的不断进步,木质能源又被誉为"生物柴油库"和"可再生电力基地",在人类生活中发挥着重要作用.文章详细介绍了国外木质能源的开发现状,分析了我国木质能源的资源状况、开发技术水平和市场条件,同时分析了木质能源的开发对经济社会可持续发展的影响.在此基础上,针对我国木质能源的开发提出了相应的建议.     

氧体积分数对木质和玉米秸秆燃烧特性的影响

采用TG-DTG-DSC联用技术对木质颗粒和玉米秸秆颗粒的燃烧特性进行了实验,考察了在不同含氧气氛中两种生物质的可燃特性、着火特性、燃烧稳定性、燃尽特性及综合燃烧特性的影响,计算了燃烧动力学参数。结果表明:随着氧体积分数的增大,两种生物质的着火温度和燃尽温度降低,燃烧稳定性判别指数、可燃性指数和综合燃烧特性指数增大;木质颗粒的着火温度和前期燃尽指数高于玉米秸秆,后期燃尽指数低于玉米秸秆,木质颗粒比玉米秸秆颗粒更难热分解,氧气体积分数对玉米秸秆颗粒燃烧特性影响要大于木质颗粒;生物质在低温阶段的活化能要大于高温阶段的活化能,两阶段的活化能随着氧气体积分数的增大而减小。     

两种不同生物质成型燃料燃烧特性实验研究

以木质颗粒和玉米秸秆颗粒两种生物质成型燃料为研究对象,通过热重分析和生物质燃烧实验台对两种成型燃料的燃烧特性展开研究并将二者的试验数据进行对比分析。实验结果表明:两种生物质颗粒燃烧过程具有相似性,但在反应速率与燃烧特征参数上存在明显差异。与玉米秸秆颗粒相比,木质颗粒着火温度高,着火时间晚,但燃尽时间短;在燃烧初始阶段木质颗粒的反应速率低于玉米秸秆颗粒,而后又高于玉米秸秆颗粒,燃烧过程中木质颗粒最大反应速率明显大于玉米秸秆颗粒;木质颗粒的可燃特性、燃尽特性和综合燃烧特性指数均优于玉米秸秆颗粒;木质颗粒在低温段和高温段的活化能均高于玉米秸秆颗粒。     

生物质直接燃烧技术的发展研究

随着能源危机和环境问题的日益严重,人们不断致力于开发研究低污染、可再生的新能源。在众多的可再生能源中,生物质能是一种储量丰富、清洁方便的绿色可再生能源,具有极大的开发潜力。为了大力开发利用生物质资源,分析比较了国内外生物质直接燃烧技术发展现状,提出应根据生物质燃料的燃烧特性,开发相应的燃烧技术和燃烧设备,以实现生物质资源的大规模集中高效利用。     

木质生物质层燃燃烧特性实验研究

搭建单元体炉层燃燃烧实验台,以松木为原料,对木质生物质的层燃特性进行研究。通过控制炉排给风量,对层燃的床层温度变化过程、床料失重情况以及床层析出气氛测定,研究木质生物质的层燃燃烧特性及相关规律。结果显示炉排给风量对木质生物质层燃的床层温度分布等燃烧特性有较为显著的影响。     

350MW超临界煤粉锅炉改燃生物质的影响

我国当前燃煤发电及供热行业碳减排压力巨大,生物质能是天然的零碳能源,是当前火力发电减碳的不二之选。本文以某350MW超临界煤粉锅炉为例,拟采用木质颗粒全部替换燃煤,通过分析化验和热力计算,探究了改用燃料对燃料着火点、燃烧稳定性、燃尽特性、烟气流量和流速、锅炉效率、炉内结渣和腐蚀等方面的影响,为后续的工程改造提供参考。     

生物质与煤矸石混烧研究综述

由于当今世界对能源的需求量很大,所以能源问题是个刻不容缓的问题。对生物质与煤矸石混烧研究情况进行了综述。概括了生物质与煤矸石燃料特性、混合燃烧特性以及二者混烧时可能存在的问题,着重探讨了玉米秸秆、葵花秸秆分别与煤矸石混合燃烧的热解特性、及动力学特性,得到了它们的混合燃烧特性。根据现阶段对生物质与煤矸石混合燃烧的研究情况以及我国生物质与煤矸石能源利用特点,对今后的研究趋势和方向做了展望,以便于缓解能源压力问题。     

海藻的燃烧特性分析

采用热重分析法,对海藻类生物质条浒苔的燃烧过程及其动力学规律进行了实验研究.通过条浒苔在不同升温速率(10,20,30℃/min)和不同粒径(＜0.18 mm,0.18 mm～0.28 mm,0.28 mm～0.45 mm)下的燃烧实验,研究发现条浒苔的失重曲线表现出明显的双峰:即挥发分峰和碳峰.分析比较了各升温速率条件下条浒苔的燃烧特性参数,发现海藻的着火点比陆上木质类生物质的着火点低,并通过计算,给出了试样的综合燃烧特性指数(S),计算结果表明升温速率越大,燃烧越容易进行.着重分析比较了不同粒径试样的燃烧特性参数,揭示了海藻呈现出与煤和陆上木质类生物质不同的性质,即燃烧速度随粒径变小而变小.由试样的燃烧动力学参数,发现试样的活化能也随升温速率变大而变大.     

生物柴油的燃烧及排放特性研究

在日益严重的能源短缺和环境污染双重压力下,世界各国正积极探索和发展发动机的代用燃料和可再生能源.生物柴油就是以生物资源如植物油或动物脂肪等作为原料通过酯化反应而得到的一种液体燃料,是清洁的可再生能源.本文介绍了生物柴油的一些特性,与普通柴油相比具有一些优越性.对生物柴油的燃烧特性试验进行了总结,并对其在不同路况及气候条件下的排放特性做了试验分析.说明生物柴油在燃烧及排放特性方面都要优于普通柴油,是一种很好的可再生能源.     

复合增压直喷汽油机缸内燃烧速度研究

为了研究复合增压直喷汽油机低速高负荷及外特性燃烧速度,搭建了试验平台,进行了大量性能试验,基于其他研究者的研究成果和研究经验,结合燃烧系统开发的工程性,提出了缸内层流燃烧速度和湍流燃烧速度分段分析法。通过该方法对试验结果进行分析,揭示了复合增压直喷汽油机低速高负荷及外特性燃烧速度特征。     

中国林木生物质能源发展潜力研究(1)

本文通过对中国部分地区林木生物质资源的实地调查研究,结合国内外生物质能源开发利用技术和国内能源需求的现状,通过分析评价中国现有180多亿t林木生物质资源总量、8～10亿t可获得量和3亿t可作为能源的利用量,阐述了大力发展林木生物质能源必要性和可行性,预测了林木生物质能源替代化石能源的发展潜力和价值。通过正常的抚育间伐、灌木平茬复壮和大力发展能源林等措施,到2020年,全国可利用林木质资源将突破10亿t,年仅消耗6000万t林木质用于直燃发电,就可实现装机容量1000万kW以上的目标。     

中国林木生物质能源发展潜力研究(2)

本文通过对中国部分地区林木生物质资源的实地调查研究,结合国内外生物质能源开发利用技术和国内能源需求的现状,通过分析评价中国现有180多亿t林木生物质资源总量、8亿～10亿t可获得量和3亿t可作为能源的利用量,阐述了大力发展林木生物质能源必要性和可行性,预测了林木生物质能源替代化石能源的发展潜力和价值。通过正常的抚育间伐、灌木平茬复壮和大力发展能源林等措施,到2020年,全国可利用林木质资源将突破10亿t,年仅消耗6000万t林木质用于直燃发电,就可实现装机容量1000万kW以上的目标。     

Energy and climate impact assessment of waste wood recovery in Switzerland

Waste wood represents as much a waste to dispose of as a secondary resource to exploit. Various studies have assessed the energy potential and/or climate impact of energy recovery from waste wood. This paper aims to assess the long-term potential of waste wood for energy production and greenhouse gas (GHG) emissions reduction in Switzerland. Material flow analysis (MFA) is applied for modelling the metabolism of wood and waste wood in the Swiss anthroposphere over one century. The energy and climate impacts are estimated for 32 scenarios which assume different forest harvesting variants and waste wood treatment options. The scenario analysis shows that waste wood treatment options are more beneficial in the long term in terms of energy production (by energy recovery from waste wood) and of GHG emission reduction than the increase in the quantities of waste wood generated in the future caused by the advocated strategies of increased forest harvesting. By using the Maximin criterion, the long-term optimal additional potential for energy recovery from waste wood is estimated at 2110 GWh/year of useful energy, which offers a reduction of 364 tonnes of CO₂ equivalents per year. As prerequisites, the nominal installed capacity of the waste wood boilers needs to be raised and their efficiency and as well as those of incineration plants need to be increased. In addition, the sustainable potential of Swiss forests must be fully exploited. This study identifies various recommendations for the optimal exploitation of energy recovery from waste wood.     

Interest in energy wood and energy crop production among Finnish non-industrial private forest owners

EU targets and regulations regarding energy production and the reduction of greenhouse gas emissions have been tightening in the 2000s. In Finland the targets are planned to be achieved mainly by increasing the use of biomass. Wood already accounts for a marked proportion of Finnish energy production, but additional reserves are still available. Energy crop production also has considerable potential. Practically all Finnish farmers are also forest owners. Therefore, private forest owners are in a decisive position regarding the supply of energy wood and crops in Finland. In this paper the future supply of biomass is examined according to their past behaviour, intentions and attitudes. Finnish forest owners have a positive attitude towards the use of wood and crops in energy production. Price is becoming more critical as a motive for the supply of energy wood. Recreation and nature conservation play a smaller role than factors related to wood production and forest management as for motives for harvesting energy wood. However, almost a half of forest owners in this study were uncertain of their willingness to supply biomass. This is partly due to limited knowledge of the issues involved in energy wood and agricultural energy crop production and the underdeveloped markets for energy biomass. In order to achieve the targets, supply should be activated by further developing market practices, information, guidance and possibly other incentives for landowners. In general, there is interest among landowners in increasing the supply of energy biomass. However, the growth of supply presumes that production is an economically attractive and competitive alternative, that the markets are better organized than at present, and that more comprehensive information is available about bioenergy and biomass markets and production techniques.     

Sustainable utilisation of forest biomass for energy—Possibilities and problems: Policy,legislation, certification,and recommendations and guidelines in the Nordic,Baltic, and other European countries

The substitution of biomass for fossil fuels in energy consumption is a measure to mitigate global warming, as well as having other advantages. Political action plans for increased use exist at both European and national levels. This paper briefly reviews the contents of recommendations, guidelines, and other synthesis publications on sustainable use of forest biomass for energy. Topics are listed and an overview of advantages, disadvantages, and trade-offs between them is given, from the viewpoint of society in general and the forestry and energy sectors in particular. For the Nordic and Baltic countries, the paper also identifies the extent to which wood for energy is included in forest legislation and forest certification standards under the “Programme for the Endorsement of Forest Certification” (PEFC) and the “Forest Stewardship Council” (FSC) schemes. Energy and forest policies at EU and national levels, and European PEFC forest standards are analysed. With respect to energy policies, the utilisation of wood for energy is generally supported in forest policies, but forest legislation is seldom used as a direct tool to encourage the utilisation of wood for energy. Regulations sometimes restrict use for environmental reasons. Forest certification standards include indicators directly related to the utilisation of wood for energy under several criteria, with most occurrences found under environmental criteria. Roles and problems in relation to policy, legislation, certification standards, recommendations and guidelines, and science are discussed.     

Review of consumption trends and public policies promoting woody biomass as an energy feedstock in the U.S.

A review of the four main wood energy sectors in the U.S. was conducted to explore historic trends and the impact of alternative energy prices and public policies on wood energy consumption. High oil prices have triggered the adoption of government regulation and financial incentives to promote greater use of wood energy over the last four decades. However, the amount of wood energy consumed in the U.S. industrial sector was driven mainly by the output of the pulp and paper products industry and not by energy prices or any particular public policy incentive. Residential consumption of wood energy was positively correlated with competing energy prices. Public policies seem to have had a greater impact on wood energy consumption in the electric power sector and over the last four decades have concentrated on promoting biopower with a recent shift to liquid cellulosic biofuels. High oil prices and a series of public policies such as tax credits, loans, grants, and renewable energy standards have resulted in higher consumption of wood energy from 2004 to 2009 in the residential, electric power and commercial sectors by an estimated 5, 2, and less than 1 percent annually, respectively. The impact of new federal programs such as the Biomass Crop Assistance Program remains to be observed. Continuation of public incentives and preferential regulations for renewable energy appears to be necessary for a steady increase in U.S. wood energy consumption.     

Economic sensitivity of wood biomass utilization for greenhouse heating application

This paper presents an analysis of the impacts of technical and market changes on the economic feasibility of using wood biomass to produce heat for an average-sized greenhouse in British Columbia. A previous techno-economic analysis determined that the installation of a wood pellet or a wood residue boiler to generate 40% of the greenhouse heat demand is more economical than using a natural gas boiler alone to generate all the heat [1]. As the techno-economic analysis contained forecasted parameters, a thorough sensitivity analysis is needed for sound decision making. This paper extends the previous techno-economic study by assessing the effect of fuel price, wood biomass energy contribution, and greenhouse size changes on the net present value (NPV) when using a wood pellet or wood residue boiler with or without an electrostatic precipitator (ESP). The results indicate that the attractiveness of using wood biomass will increase if the price of fossil fuels increases more than 3% per year or carbon taxes and regulations are applied. Increasing the biomass energy contribution by 20% (to provide 60% of the total heat demand) would still be economical. The installation of a wood pellet boiler or a wood residue boiler is economical for average (7.5 ha) or large (15 ha) greenhouses.     

Management alternatives of energy wood thinning stands

Energy wood thinning has become a feasible treatment alternative of young stands in Finland. Energy wood thinnings have been carried out mainly in stands where precommercial thinning has been neglected and the harvesting conditions for industrial wood thinning are difficult. Despite of its positive effects on harvesting costs and on renewable energy potential, whole-tree harvesting has been constantly criticized for causing growth loss. In this paper, the profitability of energy wood thinning was studied in 20 Scots pine-dominated stands where energy wood thinning was carried out. The growth of the stands after thinning was predicted with the help of Motti-stand simulator. Entire rotation time of the stands was simulated with different management alternatives. The intensity of first thinning and recovery level of logging residues varied between alternatives. In order to attain acceptable harvesting conditions, industrial wood thinning had to be delayed. The effect of energy wood thinning on subsequent stem wood growth was almost the same as in conventional thinning. Whole-tree harvesting for energy proved to be profitable alternative if the stumpage price is around 3€ m⁻³, the interest rate is 3% or 5% and the removal of pulpwood is less than 20 m³ ha⁻¹. If the harvestable pulpwood yield is over 20 m³ ha⁻¹, integrated harvesting of industrial and energy wood or delayed industrial wood harvesting becomes more profitable.     

A comparison of avoided greenhouse gas emissions when using different kinds of wood energy

In this study, micro-level data from wood energy producers in Hedmark County were gathered and analysed. The aim was to find how much greenhouse gas (GHG) emissions various kinds of wood energy cause (not only CO₂, but also CH₄ and N₂O), which energy they substitute, their potential to reduce GHG emissions, and the major sources of uncertainty. The method was life cycle assessment. Six types of wood energy were studied: fuel wood, sawdust, pellets, briquettes, demolition wood, and bark.GHG emissions over the life cycle of the wood energy types in this study are 2–19% of the emissions from a comparable source of energy. The lowest figure is for demolition wood substituting oil in large combustion facilities, the highest for fuel wood used in dwellings to substitute electricity produced by coal-based power plants.Avoided GHG emissions per m³ wood used for energy were from 0.210 to 0.640 tonne CO₂-equivalents. Related to GWh energy produced, avoided GHG emissions were from 250 to 360 tonne CO₂-equivalents. Avoided GHG emissions per tonne CO₂ in the wood are 0.28–0.70 tonne CO₂-equivalents. The most important factors were technology used for combustion, which energy that is substituted, densities, and heating values. Inputs concerning harvest, transport, and production of the wood energy are not important.Overall, taking the uncertainties into account there is not much difference in avoided GHG emissions for the different kinds of wood energy.     

火场硬木地板材料和棉花秆的变氧浓度热解燃烧动力学的试验研究

采用TG-FTIR分析方法深入研究了火场中硬木地板材料和棉花秆缺氧变氧浓度燃烧过程,深入分析了氧浓度对燃烧热失重过程的影响;首次得出了可燃物的表观活化能与实际氧浓度呈线性关系的结论;分析了氧浓度对木材燃烧气体产物的影响,并探索了氧浓度影响热解和燃烧的机理。