生物油热解气化的TG-FTIR分析

该文主要目的是了解生物油的热解气化特性及气体产物的析出特性,采用木屑快速热解生物油为对象,利用热重与傅立叶红外分析仪联用对生物油的热解气化行为进行实验研究。实验结果表明生物油的热解分为两个阶段:挥发分的快速析出(200～300℃)与生物油的碳化,生物油的热解气化符合三维扩散模型,且随着升温速率的升高热解活化能先升高后降低。红外分析结果表明生物油热解气化的主要气体产物为CO、CO_2、CH_4、H_2O和碳氢化合物等小分子气体,有机化合物的析出主要在低温段,而生物油中重质组分的裂解主要在中高温度段。     

有机固废共热解气化产物及其污染物排放特性研究综述

综述了国内外热解气化技术现状以及其遇到的问题,总结了热解气化技术特点,归纳了国内外共热解气化的研究现状;探讨了共热解的优缺点、生物质与有机工业固废、餐厨垃圾的共热解机理及其协同效应,以及在共热解过程中生物量、混合比和热解温度对共热解产物的影响。结果表明,生物质与有机固废共热解相比于单种生物质热解可以提高能源资源的利用率,并降低多种污染物的排放水平。但当前对热解气化特性差异较大的混合组分的反应机理研究仍不充分,对催化热解气化过程中催化剂的选取原则也有待深入研究。     

运行和设计参数对生物质热解制取燃料气的影响

传统的用来生产工业和民用中等热值气体的生物质热解过程面临着两个缺点，即产气率低和高含量的气相焦油蒸汽引起的下游设备的腐蚀．为克服这些缺点，在保证热解气热值几乎不变的条件下，在实验室内的一套热解系统中研究了运行和设计参数对生物质热解过程的影响．研究的参数包括反应温度、挥发相在热解炉中的停留时间、生物质原料颗粒的预处理、外部加热炉的加热速率和热解炉的热质传递能力．此外，本文还研究了一个独立的裂解炉的运行温度和热解炉的几何形状对燃料气生产的影响．结果表明，上述参数对生物质热解气的产率是敏感的，而且热解气的热值始终在13～15MJ／m^3之间变化．这一热值确保热解气可以较好地用作燃气轮机的动力燃料或炊事燃料．     

生物质热解的典型影响因素及技术研究进展

生物质通过热解可以获得热解气、生物油以及生物炭,实现其资源化、清洁高效利用。文章阐述了生物质热解过程中的反应机理,探讨了不同热解条件(如温度、升温速率和热解气氛)以及不同预处理方式(如烘焙、干燥、酸洗和水热)对生物质热解特性的影响。基于催化剂特性差异将用于生物质热解的催化剂分为固体酸和碱基催化剂并进行概述。在总结前人研究进展的基础上,梳理了有热载体和无热载体的生物质热解反应器的发展进程,针对生物质热解的研究因素较为单一的现状,提出通过围绕"微观结构-宏观调控"开展多尺度、定向调控、高效制备热解产物的方法,并对热解过程中自由基的变化研究不足以及热解催化剂失活等问题提出了展望,从而为生物质热解技术的发展提供理论依据,加快实现我国生物质的资源化利用。     

生物质固定床热解特性的试验研究与分析

对稻杆、稻壳、木屑在固定床热解反应器内的热解特性进行研究,考察热解反应温度和生物质种类对热解特性的影响,分析了热解产物的性质。结果表明,三种原料热解气的热值在１２０００￣１５０００ｋＪ／Ｎｍ＾３之间,可满足民用煤气的热值要求;产气率一般为０．２５￣０．４５Ｎｍ＾３／ｋｇ,其中稻壳的产气率最低;温度对热解产气率、生物油产率的影响很大,对热解气组份、热值、气流率及半焦产率影响也较显著;生物油的特性数据     

真空条件下金属氧化物催化废轮胎热解研究

最终热解温度为520℃的条件下，在耙式固定床反应器中研究了废轮胎橡胶粉添加不同金属氧化物作催化荆时的真空热裂解特性。实验表明，在添加2．5％CaO、ZnO真空热解时油收率有所增加，为48％左右。CaO、ZnO分别与TiO2混合后进行真空热解实验，油产率大幅度下降，而气体产率显著上升，热解炭中炭质结焦物明显降低。如ZnO／TiO2使热解气产率达到24．82％，气体热值达到28．76MJ／m^-3。添加各种金属氧化物后，热解油中的总硫含量最低为0．522％，接近国家10号重柴油标准，热解气中的H2S含量降低到25mL／m^2，体现出一定的脱硫效果。     

基于模型化合物的脱硫灰催化提质生物质热解气研究北大核心CSCD

该研究从清洁转化脱硫灰和生物质资源出发,利用自制的碳基固废热解炉研究了低温条件下(<600℃)脱硫灰对棉杆热解的催化效果。研究发现:脱硫灰明显促进了棉杆的热分解,提高了棉杆热解气产率和低位热值,提高了棉杆热解气中H_(2),CH_(4)和C_(2)H_(6)等富氢气的产量,同时,脱硫灰的催化效果降低了热解气中CO和CO_(2)的产量。通过模型化合物法研究发现:脱硫灰对棉杆中的纤维素和木质素成分生成热解气的过程有不同的催化效果;脱硫灰促进了脱硫灰/棉杆催化热解过程中纤维素生成H2和木质素生成CH4的化学反应,抑制了纤维素生成CO和CO_(2)的化学过程。     

二次热解对污泥热解产物影响的研究

针对上海市污水污泥,以提高热解气体、抑制热解焦油为目标,利用两段固定床反应器,研究二次热解温度对污泥一次热解挥发分的热解特性的影响。利用气相色谱定量研究不同二次热解温度下热解气中H2、CO、CO2、CH4的含量变化。利用全二维气相色谱-飞行时间质谱联用仪(GC×GC-TOFMS)定性研究不同二次热解温度下热解油化学组分。结果表明:二次热解温度高于600℃时,热解气体产率明显增加,液体产率明显减少。这表明,在仅改变上段固定床二次热解温度的条件下,一部分污泥热解油通过高温二次热解转化为气体。其中CH4是受二次热解影响最大的气体,相比于一次热解,当二次热解温度高达700℃时,CH4的累计释放量增加了7.0倍,这表明热效应明显促进了污泥热解挥发分的脱甲烷反应。为了更好地揭示污泥热解油转化成热解气的机理,运用GC×GC-TOFMS分析污泥热解油中上千种化合物。我们猜测长链脂肪含氮化合物主要通过脱甲烷反应产生CH4。酮类通过脱羧反应生成CO。     

两面针药渣气化工艺条件的试验研究

以水蒸气为气化剂，对两面针药渣进行热解气化工艺的研究，考察了热解气化终温、物料粒径、升温速率等因素对两面针药渣热解气化过程的影响。研究结果表明，两面针药渣热解气化的理想条件是热解终温为1100℃、慢加热速率1．02℃／s、粉末（过45目筛）状药渣，可以得到热值为11MJ／m^3的洁净燃气，产气率为1．5m^3／kg。     

水蒸气氛围下甘蔗渣热解气化条件的研究

在试验条件下，考察反应温度、升温速率、物料颗粒大小等因素对蔗渣在水蒸气中的热解气化特性的影响。试验结果表明，热解终温越高，物料粒径越小，越有利于产生高质量的热解气。热解终温是热解气化过程主要的决定因素，在先到达热解终温，再通入水蒸气的操作条件下，升温速率的改变对气化效果的影响并不突出。试验在最佳条件(采用粉末物料，在1000℃下进行热解)下，可以得到高热值(10MJ／m^3)合成气和较高的产气率(1．7m^3／kg)。     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Wind power for pumping: The development of the ITP windpump

Water pumping has been one of the main applications for wind power in the past and despite the spread of mains-electric pumps, more than a million windpumps remain in regular use. This paper reviews the general technical and economic requirements for pumping water using wind energy and by way of example gives an overview of the development of the new ITP wind-pump. It then considers the future prospects for this kind of technology.     

Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials

We describe methods for creating solar-reflective nonwhite surfaces and their application to a wide variety of residential roofing materials, including metal, clay tile, concrete tile, wood, and asphalt shingle. Reflectance in the near-infrared (NIR) spectrum (0.7–2.5 μm) is maximized by coloring a topcoat with pigments that weakly absorb and (optionally) strongly backscatter NIR radiation, and by adding an NIR-reflective basecoat (e.g., one colored with titanium dioxide rutile white) if both the topcoat and the substrate weakly reflect NIR radiation. Coated steel and glazed clay-tile roofing products achieved NIR reflectances of up to 0.50 and 0.75, respectively, using only cool topcoats. Gray-cement concrete tiles achieved NIR reflectances as high as 0.60 with coatings colored by NIR-scattering pigments. Such tiles could attain NIR reflectances of up to 0.85 by overlaying a white basecoat with a topcoat colored by NIR-transparent organic pigments. Granule-surfaced asphalt shingles achieved NIR reflectances as high as 0.45 when the granules were covered with a white basecoat and a cool color topcoat.     

Thermal decay of an initially hot isothermal water body with application to thermal energy storage

The thermal decay of an initially hot isothermal water body contained in a tank was studied. Analytical solutions (including a group-theoretic solution) were obtained for the one-dimensional heat conduction equation with heat loss from the sides of the tank. The convective heat transfer coefficient was assumed not to be constant over the surface of the tank but to vary with space and time. A very good agreement was obtained between the group-theoretic solution and a numerical solution using the Crank-Nicholson finite difference scheme. The analytical results are discussed in terms of the underlying physical mechanisms.     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

秸秆燃烧中温度对钾转化与释放的影响

通过对稻秆原料进行常规特性分析和EDX元素含量分析,发现钾在稻秆无机元素中占有重要地位。参考原料化学分馏法和土壤中钾的分类与测试方法,给出了对生物质原料及其燃烧产物中钾的定性与定量简易方法。通过程序控温型固定床对稻秆先进行缓慢氧化,然后以100℃为间隔从400～900℃进行成灰,并分别测试其成灰率、有效钾和全钾的份额。结合稻秆原料及其灰中钾的份额分析,进行了稻秆灰中有效钾转化与释放的计算,发现有效钾在700～800℃之间有快速的释放和形态转变。稻秆灰的XRD分析结果表明秸秆灰中钾主要以KCl、K_2SO_4形式存在,得到了钾以盐的形式进行转化与释放的机理。该文中燃烧温度对钾转化与释放的影响规律对设计秸秆电厂时的炉型选择和燃烧参数确定有一定参考价值。