不同催化剂下玉米秸秆热解产物特性研究

在管式加热炉中对玉米秸秆进行了热解实验研究,分别在纯秸秆热解和添加催化剂(CaO、循环流化床锅炉炉渣、炉灰)的条件下进行了对比实验研究.实验结果表明,添加催化剂后热解气中COz体积含量都有显著下降,同时,添加催化剂后热解气中可燃气成分在增加;通过实验还发现,添加炉灰能够得到最高气体产率、最低液体产率.添加炉渣能够得到最高的气体热值,与纯秸秆热解相比,气体热值提高了75.4%.     

污泥-花生壳共热解气相产物研究

采用外热式反应釜,以CH_3COOK为催化剂进行污泥-花生壳共热解气相产物的研究。考察花生壳添加量、热解温度、催化剂添加量、热解时间对共热解气相产物的产率、组成和热值的影响。研究结果表明:随着花生壳添加量的增加,气相产物的产率和热值均先增大后减小,花生壳添加量为80%时,气体热值达到最大,CH_4体积百分数达到10.57%;随着热解温度的升高,气相产物的产率和热值均先增大后减小,H_2体积百分数呈增大趋势,热解温度为600℃时,气体热值达到最大,CH_4体积百分数达到21.86%;随着催化剂添加量的增加,气相产物的产率和热值均先增大后减小,催化剂添加量为6%时气体热值达到最大;随着热解时间的延长,气相产率迅速增大后趋于平缓,气体热值缓慢增大后减小,热解时间为150 min时,气体热值达到最大值27.92MJ/m3,CH_4体积百分数达到28.33%。     

生物质在高频耦合等离子体中的热解气化研究

采用高频电容耦合等离子体热解技术对生物质原料进行了热解气化试验，研究气体产物产率、成分随反应条件的变化规律。反应在3000-8000Pa的真空范围内进行，热解温度为1000～2000K。该技术可大幅度提高生物质气的热值及产率，本试验中产气率达到了66％以上，并且还有提高的潜力。     

稻壳连续热解特性研究

在自行研制的生物质连续热解反应装置上进行稻壳连续热解和二次裂解实验研究。随着稻壳热解温度的提高,炭产率降低,气体产率增加,液体产率先增加后减少;随着滞留时间的减少,炭产率、液体产率增加,气体产率减少。稻壳热解气以CO2和CO为主,且二者为竞争关系,热解温度提高,CO2产量降低,CH4、H2、C2H4、C2H6产量增加,CO的产率变化不大;滞留时间对热解气组分影响不大。二次裂解温度提高,裂解气中的H2、CH4、C2H4含量明显增加,二次裂解温度为800℃时,H2产率达到12%。稻壳500℃热解挥发物600℃二次裂解木醋液中醋酸含量高达49.44%,焦油中检测到的物质主要为丙酮和异丙醇。     

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。     

有机钙盐预处理纤维素的热解试验研究

摘要：在管式炉上进行了预处理纤维素（CaFA纤维素）的热解实验，研究了预处理对纤维素热解特性的影响。样品红外压片分析显示预处理影响了纤维素组成单元吡喃环的稳定性，且CaFA纤维素出现了明显的羧酸根官能团振动。热解实验表明：预处理使得纤维素的半焦和气体产率增加，生物油产率下降。CaFA纤维素最大生物油产率为0.496(g/g)，相比未处理纤维素最大生物油产率降低19.1%。CaFA纤维素的气体产物中，CO含量减少，而CO2、CH4和H2含量增加，一定程度上提高了热解气相产物中的氧含量。GC-MS分析表明预处理对纤维素生物油组分具有明显的选择性，CaFA纤维素生物油中，大分子糖类及其衍生物的相对含量显著减少，而小分子酮类物质明显增加。     

城市生活垃圾中废弃木料流化床热解气化试验研究

为开发适合我国城市生活垃圾处理的低污染气化熔融技术，对城市生活垃圾中广泛存在的废弃木料组分进行了流化床热解与气化试验。流化床中，在反应温度400～700℃、过量空气系数0～0．8的范围内，对木料进行了系统的热解气化试验，分析了反应产物特性及其产量变化规律。结果表明，热解温度5000℃，热解油产量最大，可占原料质量的38％，热解气产量随温度增加而增大；气化温度600℃、过量空气系数0．4时，气化效率最高，达到73％，此时每标准立方米气化气热值为5800kJ，气化气产率为2．01m^3／kg；并进行相关的反应特性及机理分析。     

玉米秸秆催化热解制取富氢气体

文章利用管式炉反应器研究了12种催化剂对玉米秸秆热解制取富氢气体的影响,并结合气相、固相、液相产物的特性以及催化剂表征探究了物质的迁移转化规律。研究结果表明：添加10%Ni/CaO-sg的实验组达到了最佳效果,热解气产率从无催化热解时的27.8%提升至46.5%,H₂产量从53.7 mL/g上升至142.0 mL/g,H₂所占比例也从24.2%上升至32.1%;在CaO主剂的催化作用下,原料的无序性热解反应进行得更加充分,热解炭产率降低,进而在负载镍的10%Ni/CaO-sg催化作用下,热解油中的重组分芳香烃类化合物裂解成较轻的酚类,同时烷烃和烯烃含量增多,这些反应均促使热解气产率增加及氢气产量的提升。     

高温移动床废轮胎与生物质直接热解制气性能研究

对以不同比例组成的废轮胎与生物质均匀混合物在移动床内高温直接热解的制气性能进行了研究,考察了温度和废轮胎含量对产物产率、气体组分以及热值等影响。结果表明,温度对直接热解气产率和热值影响较大,温度越高,气体产率越大而热值越小;混合物中废轮胎含量增大,热解气中碳氢气体含量增多而含氧气体减少,气体产率逐渐减小而热值增大。温度升高,合成气(H2+CO)含量和H2/CO比值均增大;废轮胎含量增大,合成气(H2+CO)含量和H2/CO比值先增大后减小。当热解温度为1 000℃,废轮胎含量为35%时,热解产物中(H2+CO)含量最高为61%,且H2/CO的比值达到最大值为1.53,有利于作为工业合成气原料。同一温度下,混合物直接热解气热值远远高于生物质单独热解,说明废轮胎的掺入有助于优化热解气组成,提升燃气品质。     

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．     

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.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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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.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.