煤电化学脱硫试验研究

为了研究电解前后煤中硫分的变化,对含硫量为3.08%的高硫煤样进行电化学脱硫处理。用氢氧化钠溶液浸泡煤样后进行电化学处理,对电解后煤样进行洗涤、过滤、烘干。采用X射线荧光技术、X-射线衍射技术和红外光谱仪等检测手段,分析电解后煤样元素和有机基团的变化。实验结果表明:电解后煤中硫铁矿、双硫键明显较少,说明电解反应可以脱除煤中大部分硫。     

白腐菌煤炭脱硫实验研究

将白腐菌用于煤炭脱硫的实验研究,通过实验研究了白腐菌在煤炭脱硫过程中煤粒度、煤浆浓度、接种量和培养时间等各因素对其脱硫的影响。实验表明,白腐菌脱除广西合山煤中全硫的最佳条件是：煤粒度〈200目,煤浆浓度10％,白腐菌菌种量0．9g,白腐菌培养时间为5d。在最佳条件下,全硫的脱除率为35.77％。     

煤微生物脱硫净化技术

微生物煤炭脱硫是在创造出适宜的含微生物流体湍流流动状态前提下，利用微生物氧化和表面改性原理将煤炭中的硫脱除的技术；在煤水混合物中利用不同微生物的脱硫活性将煤中的硫脱除。在与微生物分离之后，煤浓缩在煤水混合物中；微生物经过再生后可循环利用。通过微生物处理，可以更大限度地获得煤炭的潜在热值及降低煤炭中的灰分含量。     

煤灰中硫元素的脱除机理与方法研究

归纳了煤中有机、无机硫的脱除机理和脱硫方法,按脱硫机理将脱硫方法分为物理脱硫法、化学脱硫法和微生物脱硫法,评价了目前各种脱硫方法的优缺点,及物理、化学与微生物脱硫方法目前的研究进展。在此基础上,提出了多种方法优化组合可实现高效、低成本脱硫,并对其前景进行了展望。     

还原条件下煤中硫的转化

在小型流化床实验台上对还原条件下硫化物的生成进行了研究.实验结果表明,还原态条件下燃料中的硫首先生成H2S,以及少量的SO2.作者认为SO2主要是由硫酸盐的分解形成的.H2S产生速率受还原性气氛、有机硫比例以及含氧量的影响很大,还原性越强,有机硫比例越大,含氧量越低产生的H2S越多;H2S产生的速率还与煤中挥发份含量和有机硫含量有关,挥发份含量越高,有机硫含量越低,H2S产生越早;低按发份和低有机硫含量的煤在强还原性气氛下容易生成单质硫.因此,循环流化床的脱硫过程中必须采取有效措施去除燃烧过程中产生的H2S,特别对于燃烧高硫煤种.图6表2参12     

高温固硫物相硫铝酸盐的研究进展

固硫产物的稳定性是影响煤燃烧过程脱硫效果的重要因素，硫铝酸盐（C4A3S）是一种高温下（低于1400℃）非常稳定的固硫物相，又是新型特种水泥的主要原料，研究该物相的生成机理对提高固定床及煤粉炉内煤燃烧过程的脱硫效果具有指导意义。论述了不同气氛下硫铝酸盐的生成机理和添加剂对该物相形成的影响，提出将含硫铝酸盐的固硫煤渣用于烧制水泥熟料将有很好的应用前景。     

淖毛湖煤加氢转化过程中硫和氮的迁移规律

基于硫、氮含量对新疆低变质煤热解炼制油气品质的重要影响作用,本实验通过建立多功能煤热解转化实验台,并结合XPS先进测试方法,充分考察了不同温度对新疆淖毛湖煤加氢转化中硫、氮迁移规律的影响.研究结果表明,原煤和低温半焦中的硫主要为噻吩硫、硫砜和硫酸盐等.低温热解条件下主要为不稳定有机硫的分解;当热解温度高于600℃时煤焦表面形成大量硫化物;随着温度的进一步升高,硫酸盐在高温热力环境下逐渐分解.原煤中的氮主要为吡咯氮及少量氮氧化物.低温热解阶段吡咯向吡啶转化,高温阶段吡咯和吡啶向季氮快速转化.当热解温度升高至800℃时,吡咯氮转化完全,季氮和吡啶氮为半焦中氮的主要形式.     

柴油氧化脱硫技术研究进展

随着环保法规的日益严格,世界各国都制定严格的柴油硫含量标准,生产超低硫柴油已成为世界各国的研究热点。加氢脱硫技术生产低硫柴油,由于耗氢量大、设备投资大、操作条件苛刻、操作费用较高等技术经济问题,导致柴油生产成本大幅攀升。柴油氧化脱硫技术因其在较温和的条件下即可得到超低硫油品而引起人们的广泛关注。介绍了离子液体催化氧化脱硫、相转移催化氧化脱硫、光催化氧化脱硫、空气催化氧化脱硫及有机酸催化氧化脱硫。分析了不同方法的反应机理和优缺点,认为空气催化氧化脱硫技术克服了以H2O2为氧化剂的氧化脱硫技术的缺点,并具有操作条件缓和,反应时间短等优点,随着众多研究者不断深入研究,进一步提高该方法的脱硫率和成品油收率、改善其对不同柴油的适应性等,空气催化氧化脱硫技术将成为柴油氧化脱硫的主要研究方向。     

原煤低温空气氧化法预脱硫影响因素的实验研究

针对4种不同煤种的高硫煤，在固定床反应器中考察了原煤空气气氛低温氧化预脱硫过程的影响因素，包括煤种（总硫含量、形态硫分布和挥发分含量）和化学反应条件及传质条件（温度、停留时间和颗粒粒径等），处理前后的样品中硫形态根据GB/T215-1996分析，硫和碳的含量分析用LECO SC-444定碳定硫仪测试。实验结果表明，反应条件和煤种是影响硫析出的两类因素，煤中黄铁矿硫在400℃停留10min时，均可达到50％的脱除率，最高达到80.08％。对于高挥发分的煤，宜选择低的转化温度，较短的停留时间，并适当增加颗粒粒径，以控制高的碳和热量损失；对于低挥发分的煤，可增加反应温度和停留时间，相应降低颗粒粒径以增加硫析出率。400℃停留10min操作条件下，大同半焦中硫含量从原煤中的1.48％可降至0.62％，此时碳和热值损失分别为13.64％和16.22％。在500℃停留10min操作条件下，阳泉半焦中硫含量从原煤中的1.59％降至1.07％。     

煤洁净燃烧添加剂技术的研究

从研究煤中硫的析出规律入手,分析了钙基吸收剂在高温下固硫率低的原因,及有机硫和无机硫的不同析出规律,选择具有促进或催化作用的工业废料,与钙基固硫剂按比例掺混,形成一毓既可直接在燃烧过程中脱硫,又有一定催化燃烧作用所洁净燃料添加剂。     

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%.     

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.     

Contents in Volume 23,2014

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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.