油棕废弃物热解特性及产物分析

文章采用热分析仪分析了不同升温速率下油棕废弃物的热解特性,并通过Py-GC/MS技术对其热解产物进行了定量分析。分析结果表明:油棕废弃物的热解过程分为脱水、预热解、主要热解和炭化4个阶段;升温速率对油棕废弃物热解的TG曲线影响很大,当热解速率从10℃/min增加到50℃/min时,TG曲线逐渐向右偏移,随着热解速率增大,残余质量增加;在主要热解阶段,失重率为总失重的66%~71%。快速热裂解过程中检测出了115种挥发性物质,根据化学结构的不同,主要分为9类,其中,酸类和烃类化合物的含量占挥发性物质的51.72%,芳香族化合物的种类最多,共有34种,酸类化合物中的脂肪酸均为长链脂肪酸。     

烘焙预处理对小球藻热解特性与产物分布的影响

文章通过在不同升温速率下进行烘焙小球藻的热重实验,探究其在40～900℃下的热重反应特性,采用分布式活化能模型（DAEM）计算烘焙后热解活化能,揭示烘焙对其热解动力学的影响。采用热重-红外联用仪分析烘焙小球藻的热解气体变化规律,采用Py-GC/MS探究在不同热解温度（500℃和900℃）下烘焙小球藻热解生物油的变化规律。结果表明：烘焙预处理增加了小球藻的热解活化能,同时促进了小球藻在热解过程中含氮产物的生成;烘焙后小球藻在900℃下发生热解时,以生成轻质芳烃和烯烃类产物为主,几乎不产生含氧化合物,且烘焙预处理更容易使生物油发生裂解,最佳烘焙温度为250℃。     

烟煤与油页岩热解液体产物组成及性质的研究

本文以两种烟煤和一种油页岩为原料,利用处理量为2.5 kg/h的热解实验装置进行煤与油页岩的热解实验,采用CP-3800和GC/MS分析仪分析了热解液体产物的组成及性质,实验结果表明:液体产物主要由长链烃、酚类化合物及稠环芳烃化合物等组成.在435℃、481℃、555℃时,六级煤液体产物中含量最高的分别为:长链烃、非酚含氧化合物、酚的衍生物;440℃时,造气入炉煤焦油中长链烃含量达到50.85％,油页岩在430℃时,长链烃占焦油总量的55.464％.     

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。     

水热/水热氧化处理过程中棉秆三组分对其热解行为的影响

文章基于新疆棉秆的微波水热及水热氧化处理实验,利用傅立叶红外光谱分析、Van Soest化学组分分析和热重分析等方法,研究了水热及水热氧化处理对棉秆固相产物结构、组分变化及热解特性的影响规律。研究结果表明：水热处理过程中,棉秆中的半纤维素在温度为200℃时基本完全水解,无定形纤维素在温度为200～230℃时剧烈分解,而木质素与结晶纤维素在温度为160～230℃时保持稳定;随着水热温度的升高,棉秆样品的结晶度、固定碳含量、热值均呈上升趋势,灰分和水分含量则呈下降趋势,综合热解指数在温度为200℃时达到最大值[4.07×10^-5%³/(min²·℃³)];水热氧化处理过程中,半纤维素在温度为180℃时基本分解完毕,木质素和结晶纤维素在温度为160～230℃时发生部分降解;在水热氧化温度为160～200℃时,棉秆的结晶度升高至最大值后降低;水热氧化处理后棉秆的固定碳含量和热值均高于同温度下的水热处理后棉秆,且综合热解指数在温度为180℃时达到最大值[4.23×10^-5%^3<...     

废弃印刷线路板真空热解产物的研究

自行设计热解装置,对废弃印刷线路板进行了真空热解,并对热解产物进行了分析。在热解终温550℃,升温速率10℃/min的条件下,得到的热解产物中液、气体、固三种产物的质量分数分别为18.13%、8.5%以及73.37%。对热解液体进行常压蒸馏后进行气相色谱—质谱联用分析,发现热解油中主要成分为苯酚和4-异丙基苯酚,且主要分布于110~230℃的馏分中,而110~230℃的馏分可以占到热解液体产物的50%以上,热解液体中水分含量17.32%左右,同时检测到2-溴苯酚的存在。而热解气体产物通过气相色谱检测,发现主要成分为CH4、H2、CO、CO2等,其中CO2主要生成于反应的初期,随着热解温度的升高,CO2含量急剧下降,而CH4和H2的含量快速上升。热解气中可燃性高热值气体含量高,可以通过燃烧实现热量回收。     

油泥-煤混合燃料热解产物的研究

利用色谱分析技术对油泥-煤混合燃料热解产物的析出规律进行研究。研究表明油泥-煤混合燃料热解主要产物为H2、N2、CO2、CO、CH4、C2H6、C2H4、C3H8和C3H6。无机气体产量在热解温度900℃达到最大值,烃类气体产量在热解温度650℃达到最大值。热解产物产量在煤占混煤比例为40%时达到最大值。     

松塔热解特性及热解过程气体产物分析

文章以废弃松塔为原料,采用热重分析的方法,研究了松塔热解失重规律,通过管式炉热解实验,研究了松塔热解过程中气体产物的变化规律。研究结果表明:松塔热解分为3个阶段,200～500℃是松塔热解的主反应区间,最大失重峰出现在338℃,热解反应过程存在两个较明显的DTG曲线肩峰,且这两个DTG曲线肩峰均与松塔抽提物有关;松塔热解过程中会产生大量的CO_2,同时还有CO,CH_4和H_2O的产生和芳香族化合物的出现;当热解终温为600℃时,随着升温速率的提高,管式炉热解产物中的固体产物得率逐渐降低,液体和气体产物得率逐渐增加,液体产物得率的增幅逐渐变小;当升温速率为80℃/min时,气体累积热值呈现出先增加后略微降低的变化趋势,在热解的第668 s,气体热值达到最大值11 064 kJ/m~3。     

烟杆热解固体产物性质及其影响因素研究

利用热重分析仪和马弗炉研究了温度和时间对烟杆热解固体产物性质(工业分析组成、发热量等)的影响.在温度为300～600℃,热解时间为30 min和60 min两种工况条件下,分别研究了烟杆热解固体产物性质随温度的变化.结果表明,随着热解温度的升高,热解固体产物中固定碳比例和发热量先升高后降低,在550℃时达到最高值.热解...     

生物质玉米芯热解动力学实验研究

以玉米芯为对象,利用热重-质谱联用技术,以高纯氩气为载气对其进行了详细的热重分析研究。通过对10℃/min和30℃/min升温速率及其不同温度下的失重曲线分析,发现玉米芯的主要失重温度区间为200~400℃,峰值温度为328~345℃。随着升温速率的提高,玉米芯热解的初始温度升高,热解向高温侧移动。同时通过质谱分析获得了温度和升温速率对热解气化产物的影响规律。在此基础上建立了热解动力学模型,并根据实验数据对模型进行了求解,结果表明玉米芯热解在低温段属一级反应而在高温段属三级反应。     

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.