贮压式钢制沼气罐

中国专利产品——贮压式钢制沼气罐是高效沼气发生装置。发酵原料的浓度大，料液温度高，消化彻底，可连续进料和出料，产气持续时间长。该装置的产气量是同容积普通沼气池产气量的3倍；沼气中甲烷含量达80%～87%，燃烧热值高；     

户用沼气系统运行效果的技术评价指标体系

用层次分析法构建了户用沼气系统的技术评价指标体系,通过德尔菲法构建了评价指标的判定方法学,从而为评价户用沼气系统的运行效果提供理论依据和技术支撑。将户用沼气系统分为5个子系统:构筑物系统、产气系统、沼气输送系统、沼气利用系统、沼液沼渣处理系统。将此评价体系用于评估某国户用沼气系统的运行效果,结果表明,如果仅以正常产气衡量,则正常运行的概率为76%;如果综合考虑沼气系统各个方面,则运行良好的概率仅为1%。     

沼气发酵技术为柠檬酸厂立大功

湖南省宁乡县柠檬酸厂每年生产柠檬酸1．3万Ik每天要排放近200t污水,严重污染了周围的环境。1992年,该厂领导决定投资150万元修建一套大型沼气发酵系统,该系统发酵罐的容积为600m’,气柜的容积为625m3,采用高温厌氧发酵技术。几年来,这座大型沼气发酵系统运行情况良好,处理污水的效果令人满意。经发酵处理后的污水达到了国家的排放标准,并成了受当地农民喜爱的高效肥料。除此以外,该系统每日还能产1500m‘沼气,保证了本厂职工和附近700多户居民的生活用能,同时还可供给该厂两个食堂的炊事用能和机关办公室的冬季取暖用能,取得…     

畜禽养殖场沼气工程运行温度的确定方法

为实现沼气工程运行的净产能最大化,以万头猪场配置的500 m3发酵罐为分析对象,建立计算模型,计算净沼气产量,从而确定发酵温度。结果表明：发酵罐的能量产出效率指标k和能量输入效率指标η是发酵温度选择的决定性因素；在现有设计条件(k=55%、w=45%、发酵温度35 ℃)下运行,年增温所需沼气量为总沼气产量的42.4%,其中,冬季为65.2%,春季为42.1%,秋季为40.4%,夏季为22.3%,年平均净沼气产量为285.6 m3/d;只有当k≥55%和w≥45%时,运行净能产出最大的发酵温度为35 ℃,当k或η值随工程运行下降,降低发酵运行温度方可获得最大净能产出；结合我国沼气工程的实际工况,建议选择30 ℃作为发酵运行温度,并及时对发酵设备进行维护,以确保工程的长期运行效率。     

户用太阳能恒温沼气生产系统批式半连续发酵产气性能试验

在甘肃省民勤县测试户用太阳能恒温沼气生产系统以半连续工艺发酵的产气性能。在当地冬季气象条件下,产气系统半连续补料厌氧发酵试验结果发现:该系统采用半连续补料发酵可在冬季最低环境温度为-18.2℃时连续稳定运行。在116 d试验期内,平均日产沼气0.95 m~3,累计产气110.71 m~3;当达到最低环境温度时,系统可实现在(27±2)℃的范围内的稳定产气;批式厌氧发酵过程半连续补料可维持较稳定的甲烷含量,平均甲烷含量为54.74%;另外,该产气系统在基质浓不变的度条件下可通过调节发酵温度,满足不同时期4～5口人家庭的生活燃气用量的需求。     

基于中温两相厌氧发酵技术的不同配比牛猪粪对寒地户用沼气的影响

设计一种位于日光温室内并采用中温两相厌氧发酵装置,在前期单一牛粪为发酵原料的基础上,在其中加入一定量的猪粪,探讨所设计的新型农村户用沼气发酵装置产气量与维持发酵罐体内料液温度所消耗沼气量之间的关系。结果表明:当牛粪与猪粪混合液总固体含量为1∶1时,该沼气发酵装置最高池容产气率为1.5L/(L.d),比单一牛粪为原料的池容产气率(1.35L/(L.d))高,是传统沼气池产气率(0.35L/(L.d))的4倍多。日均结余沼气量为7.85m3,足以满足三口之家照明、炊事所需能源,实现高寒地区户用沼气全年正能输出,而且装置结构设计合理,设备完善,可取代传统沼气池。     

畜禽养殖场沼气工程发酵温度的确定方法

为实现沼气工程运行的净产能最大化,以万头猪场配置的500m3发酵罐为分析对象,建立计算模型,计算净沼气产量,从而确定发酵温度。结果表明:发酵罐的能量产出效率指标k和能量输入效率指标η是发酵温度选择的决定性因素;在现有设计条件(k=0.55、η=0.45、发酵温度35℃)下运行,年增温所需沼气量为总沼气产量的42.4%,其中,冬季为65.2%,春季为42.1%,秋季为40.4%,夏季为22.3%,年平均净沼气产量为285.6m3/d;只有当k≥0.55和η≥0.45时,运行净能产出最大的发酵温度为35℃,当k或η值随工程运行下降,降低发酵运行温度方可获得最大净能产出;结合我国沼气工程的实际工况,建议选择30℃作为发酵运行温度,并及时对发酵设备进行维护,以确保工程的长期运行效率。     

温度对蔬菜垃圾与猪粪混合消化产沼气特性的影响

采用批式厌氧消化实验,在10 L反应系统中将蔬菜垃圾与猪粪以1∶2质量比进行混合发酵,探究温度(20、32、37、52℃)对二者混合消化产气特性的影响。结果表明,中、高温(32、37、52℃)条件下混合发酵系统稳定,室温(20℃)发酵后期有轻微酸抑制。32℃时产沼气性能最佳,总产气量分别是20、37和52℃时的4.65、2.08和1.42倍,发酵过程中p H值、挥发性脂肪酸和氨氮浓度均在正常范围。3 m~3户用沼气池试验表明,蔬菜与猪粪32℃混合发酵的池容产气率为0.56 m~3/(m~3·d),平均甲烷体积分数为54.83%,日平均产气量为1.68 m~3。蔬菜与猪粪32℃混合发酵既可维持发酵系统稳定性,又能改善产沼气性能,为蔬菜废弃物的沼气化处理提供参考。     

基于PLC和组态软件构建沼气发酵控制系统

根据沼气干发酵工艺流程和控制要求,提出了基于PLC和组态软件的沼气发酵自动控制系统。该系统能够实现鄂尔多斯示范工程沼气发酵生产过程的实时监控和自动控制。系统能够利用组态软件KingView6.55在沼气发酵系统中完成数据的上传下达、组态的开发、功能的分析、监控画面的建立、计算机与PLC的通讯,实现沼气发酵过程的高产气率和设备的稳定运行。针对鄂尔多斯示范工程中有效容积为300 m3的立式厌氧发酵罐及整套工艺设备进行了调试与运行,结果表明:在该系统自动控制下,21 d后发酵过程达到了稳定状态,沼气日产气量达到360 m3,且沼气中甲烷含量达到56%以上。     

浙江援助摩洛哥沼气工程新进展

1.ATLAS村沼气发电工程主要设备:80m~3和100m~3沼气池各一只,50m~3气柜一只,沼气脱硫塔,8kW沼气一柴油发电机.发酵原料为牲畜粪,发酵温度30±1℃(用太阳能加温),年平均产气率超过0.5m~3/(m~3·日),脱硫塔可除去沼气中90%的H_2 S.沼气-柴油发电机设计节油率为60%～70%,实测已达82%-84%. 此工程可为该村24户村民提供晚上5小时照明和看电视用电及白天4小时抽水用     

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%.     

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。     

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.