产氢细菌对不同单双糖的发酵产氢利用与效能

采用间歇培养方法,分别以单糖(葡萄糖、果糖、半乳糖和甘露糖)、双糖(蔗糖)作为产氢微生物培养基中的底物,对产氢微生物培养过程中的产氢效能进行了研究,探索产氢细菌对不同单双糖的发酵产氢的利用与效能.研究结果表明:不同单糖之间的气体产量差别较小,但是底物浓度对氢气产量影响很大;葡萄糖浓度10g/L是产氢菌SUES-1生长、产氢的适宜底物浓度;双糖(蔗糖)的产氢量大于相同浓度单糖(葡萄糖)的产氢量.     

微波-盐酸水解啤酒糟对其发酵产氢的影响

以啤酒糟为底物的厌氧发酵产氢技术可以同时实现废物资源再利用和清洁能源生产。为提高啤酒糟的产氢能力,探讨微波-盐酸预处理底物对厌氧发酵产氢的影响,将啤酒糟置于质量体积分数为的1%HCl中,在微波下辐射加热10 min,以未处理和微波-盐酸热处理啤酒糟为底物进行批式厌氧发酵产氢试验研究。结果表明:微波-盐酸预处理能显著提升啤酒糟的糖化与产氢能力;预处理后,啤酒糟的初始还原糖浓度是未处理啤酒糟的30倍,最大氢气浓度由23.18%提高到34.18%,产氢率由25.76 m L/g提高到52.81 m L/g;修正的Gompertz方程可以很好地拟合累积产氢量随时间的变化;啤酒糟发酵过程中的挥发性脂肪酸以乙酸和丁酸为主。     

预处理温度对活性污泥发酵产氢特性的影响

为寻求适宜的种泥热处理方法,利用摇瓶发酵实验,考察了城市污水处理厂好氧活性污泥分别经65、80、95、110℃热处理30min后,其利用葡萄糖发酵产氢的特性。结果表明:在初始pH=7.0、葡萄糖浓度10g/L、接种量2gMLVSS/L条件下,35℃培养72h,经65℃和95℃处理的种泥表现出较好的发酵产氢性能,其葡萄糖的氢气转化率分别达到1.08和1.11mol/mol,污泥的比产氢率分别为8.36和9.05mmol/gMLVSS;经65℃预处理的种泥发酵体系,表现为丁酸型发酵,其葡萄糖降解率和最大产氢速率分别高达82%和11.29mL/h,而经95℃预处理的种泥发酵体系则呈现混合酸发酵特征,其葡萄糖转化率和最大产氢速率分别仅为76%和4.45mL/h。     

糖蜜废水COD/N对厌氧发酵产氢的影响

采用批式厌氧发酵的方法,研究了在5种不同COD/N条件下糖蜜废水的产氢量、pH值及VFA的变化情况.研究结果表明,底物COD/N对糖蜜废水产氢量的影响极大.当COD/N低于60时,产氢受到抑制;当COD/N为20时,产氢活动完全受到抑制;当pH值高于8.73时,产氢量为零.较适宜的COD/N为100和80,此时产氢启动快,产酸代谢能力强,累积产氢量高.     

复合有机氮对产氢新菌C.guangxiense产氢的促进作用

文章就有机氮源的复合配比对梭菌属新菌种的模式菌株C. guangxiense ZGM211T在发酵产氢过程中的生长和产氢的促进作用进行探讨。通过对产氢量、葡萄糖利用率、细胞干重和终点pH的研究,发现无机氮源无法被菌株ZGM211利用,而3种有机氮源可以通过不同途径影响菌株的产氢量:蛋白胨对细胞生物量的增长有明显的促进作用;牛肉膏的投加提升了底物的利用效率,并促进了氢气产量的增加;酵母粉不仅可以提升生物量,还对产氢有明显的促进作用。在培养基中投加3种有机氮源时,菌株ZGM211的产氢效率明显优于投加等量的双氮源或单一氮源。在最适宜的复合氮源(蛋白胨∶牛肉膏∶酵母粉=1∶2∶3)条件下,菌株ZGM211的最大产氢量(以单位体积培养基计)为63.40 mmol/L,葡萄糖利用率高达73.30%,细胞干重为1.48 g/L。     

一株纤维素降解新菌种发酵玉米秸秆的生物产氢特性研究

试验从连续流发酵产氢反应器（ZL92114474．1）中分离筛选出一株高效纤维素降解产氢细菌Clostridilan sp．X9。X9利用微晶纤维素（MC）作为发酵产氢底物,得到最大单位体积产氢量（YH2）、比产氢率（YH2／s）和纤维素降解率分别为780mL H2／L-culture、5．1mmol H2／g-cellulose和69．6％。采用酸、碱、氨水和酸化汽爆方式预处理玉米秸秆,结果表明,酸化汽爆方式可以获得最佳的预处理效果。x9利用酸化汽爆玉米秸秆（cSES）发酵产氢的YH2、YH2／s和纤维索降解率分别达到730mL H2／L-culture、4．3mmol H2／g-cellulose和64％。这说明新菌种X9在利用玉米秸秆类生物质纤维素发酵产氢方面具有很好的应用潜力。     

聚球藻自相发酵产氢研究

研究了培养基的pH值、盐度和氮源等对聚球藻生长及自相发酵产氢的影响。发现聚球藻在弱碱性时(pH=7.5~8)不能正常生长,当pH值高于8.5时藻才能实现富集,当碱性进一步增强到pH值9.5时藻生长状态最佳。收获藻液置于黑暗厌氧条件下利用自身氢酶进行自相发酵产氢,单位干重的产氢量达到22.25mL/g。聚球藻无法适应高盐度环境,在盐度较低情况下(0.154 mmol/L)才能迅速生长,得到自发酵产氢最大值为25.68 mL/g。加入无机氮源能明显提高聚球藻的生长速率及生物质产量,但对随后产氢效果有抑制作用。     

厨余与污泥联合发酵不同预处理产氢特性研究

以厨余垃圾和污泥为反应底物,加热预处理的污泥为发酵接种物,考察了对反应底物进行碱、酸和热3种预处理的发酵产氢特性.试验结果表明:经过预处理的反应底物中的可溶性营养物质(SCOD和还原糖)总量有明显增长;预处理后发酵所产氢气含量、比产氢速率和氢产率都有较大改善,其中以加热预处理提高效果最为明显,最大氢气含量、最大比产氢速率(VS)和最高氢产率(VS)为47.68%,2.89 ml/(h·g)和57.74 ml/g,相对于未经过预处理的发酵样品分别提高了0.89倍,5.14倍和3.16倍.     

牛粪、鸡粪发酵产氢潜力的研究

采用恒温厌氧发酵工艺,用乳酸调控发酵pH值,进行了牛粪和鸡粪发酵产氢的实验研究。实验结果表明,pH为4.7～5.5时,牛粪的产氢潜力为32.33ml/g(TS)和41.39ml/g(VS);鸡粪的产氢潜力为33.58ml/g(TS)和50.88ml/g(VS)。     

Fe对产氢发酵细菌发酵途径及产氢能力影响

经过对20株产氢发酵细菌的静态发酵试验，结果发现加入Fe的培养液中细菌发酵由原来的丁酸型发酵过程向乙醇型发酵过程转化；在有机物发酵产氢的两个主要途径中，Fe为必要成分之一，其参与促进酶促反应的进行。在相似培养条件下，单质Fe与Fe^2 均可诱导细菌代谢向乙醇型发酵转化，其中单质Fe的作用能力优于Fe^2 ；在细菌代谢过程中，单质Fe具有提高细菌发酵产氢能力的作用。     

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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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.     

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.