竹材流化床气化试验研究

利用自制的小型流化床气化炉,在400～700℃、过量空气系数0.2～0.8的范围内对竹材进行了气化试验研究。当气化温度为700℃、过量空气系数为0.2时,气化气热值最高,达到7200 kJ/Nm3左右;当气化温度为700℃、过量空气系数为0.4时,气化效率最高,达到60%左右;气化气产率与过量空气系数呈线性正相关,几乎与反应温度无关;当过量空气系数达到0.6以上、反应温度达到500℃以上时,碳转化率可达到85%以上。     

垃圾循环流化床低温气化试验研究及模拟

在一台自行研制的循环流化床气化炉上进行了模拟城市生活垃圾低温气化试验.结果表明,随气化温度升高,气化气体低位热值明显增高,可燃组分含量也随之增大,尤其是当气化温度从500℃升高到600℃时,气化气体中CO、H2和CH4含量显著增加;随着过量空气系数的增大,气化气体中可燃组分含量和气化气体低位热值均减小;垃圾中适当保持一定水分含量有利于提高其气化气体中可燃组分含苗和气化气体低位热值.同时采用ASPENPLUS软件建立了垃圾流化床气化模型,通过改变气化温度、过量空气系数和垃圾全水分含量进行模拟计算,结果显示,各工况下生成气化气体低位热值的模拟值和试验值符合较好,证明该模型可用于城市生活垃圾气化特性的预涮和分析.     

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)。     

松木锯屑CO2-水蒸气气化制取富氢气体工艺条件的试验研究

以CO2-水蒸气为气化剂,松木锯屑为原料,进行热解气化试验.研究了气化温度、水蒸气添加量、催化剂添加量对产氢率的影响.在650-850℃范围内,H2含量从12.38％增加到21.92％,增长了9.54％.在0-2.5kg/h水蒸气添加量范围内,H2含量从12.07％增加到17.98％.但过量水蒸气的加入会导致反应器内温度下降,不利于制氢反应.CaO作为催化剂,当其含量为0～3％时,气化气中氢气含量上升约10％.但当其含量大于4％时,氢气含量下降较大.     

PE塑料和橡胶的流化床气化特性

在过量空气系数为0.3～0.4的条件下,研究了PE塑料和橡胶在不同温度下的流化床气化特性,包括气化产物的组成、质量分数和能量转化率,分析了温度对气化反应的影响.结果表明,PE的气化对温度不敏感,在较低温度550℃时即可达到很好的气化效果,能量的转化率达到80%以上;而温度对橡胶的气化有显著的影响,在较高的温度750℃时气化效果较好,能量转化率为78.76%.     

烟煤煤焦的CO2气化反应

采用TG-FTIR方法,在反应温度为950～1300℃时,研究了几种典型煤种及其在高温下慢速和快速热解煤焦的CO2气化反应特性.对4种原煤及其1200℃快、慢速热解条件下煤焦气化产物CH4和CO进行了实时检测和分析.同时对煤焦的孔隙结构和化学组成进行了分析.结果表明,各种热解煤焦的反应速率随气化温度的升高而增大,当达到最大值后随温度的升高而下降;4种煤焦的活化能随热解和气化温度的升高而增大;煤焦气化过程释放CH4和CO的特性与原煤的趋势相似,但原煤热解气化过程中释放CH4的质量浓度比不同热解速率制得煤焦的热解气化释放CH4的质量浓度高出2个数量级,快焦相比慢焦释放出更高质量浓度的CH4;各种煤焦的BET比表面积都较小(除神府慢焦外都小于2 ㎡/g);快焦的气化活性比慢焦的好.     

新型医疗垃圾焚烧炉热力计算及优化

对新型控气式医疗废物热解气化焚烧炉进行了热力分析,针对医疗废物的特点,利用物料平衡与能量平衡的原理,对焚烧炉的炉膛整体、一燃室以及二燃室进行了计算分析,得出总的过量空气系数和一燃室的过量空气系数对焚烧炉出口温度和一燃室出口温度的影响规律,当总过量空气系数从1.6上升到2.0时,一燃室出口温度从640 ℃上升到1 150 ℃,同时焚烧炉出口温度1 000 ℃逐渐降低到650 ℃.当总过量空气系数不变,一燃室过量空气系数从0.36变化到0.5时,一然室从700 ℃上升至1 100 ℃,二燃烧室的温度则维持在900 ℃.在实际医疗焚烧炉上进行了燃烧试验,试验结果与计算结果符合较好.     

污泥再燃脱硝特性试验研究

为分析再燃区温度、污泥含水率、过量空气系数和停留时间对污泥再燃脱硝特性的影响,对污泥再燃脱硝特性进行试验研究。采用配气法模拟流化床锅炉燃烧产生的烟气,使用污泥颗粒作为再燃燃料,通过立式管式炉进行再燃试验。结果表明:在再燃区温度为850～950℃时,随着再燃区温度升高,NO和N_2O的还原率均升高;水分对NO和N_2O的还原机理影响不同,含水率为10%～15%时,NO_x的还原率较高;在过量空气系数为0. 7～1. 0时,随过量空气系数升高,NO和N_2O的还原率减小;在停留时间为0. 45～0. 7 s时,随停留时间增大,NO和N_2O的还原率增大。     

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。     

生物质鼓泡流化床气化特性的空气当量比影响分析

在鼓泡流化床生物质气化器内,以空气为气化介质,对木屑进行了常压气化试验研究。选择空气当量比ER为0．13～0．33进行试验,研究了在气化温度为760％、810～12和860℃条件下对气化结果的影响。试验结果表明：主要燃气成分含量H2：6．2％～14．1％,CO29．9％～30．2％,CH4：1．6％～11．2％,产气率：1．0m3／kg～1．740／kg,产气低位热值：3526kJ／m3～9184kJ／m3,碳转换率：52．3％～82．3％,气化效率38％～69．1％。     

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

<正>~~     

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。     

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.     

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.