基于UASB反应器的厨余厌氧发酵产氢研究

针对目前厨余连续流发酵产氢处理负荷不高、产氢率较低的难题,采用UASB反应器进行厨余发酵产氢研究。在温度为30℃,进水COD浓度为2 000~10 000 mg/L,水力停留时间为2~6 h条件下,产氢速率最大达到17.04 L/(L.d)。反应器内有颗粒污泥的形成,平均生物量达到6.17 g/L,为氢气的产生提供了有利保障。当出水pH为4.2~4.4,碱度为260~340 mg/L的条件下,乙醇和乙酸占挥发酸总量的89.2%,形成稳定的乙醇型发酵类型,反应器最高处理负荷COD达到60 kg/(m3.d)。试验结果表明,UASB反应器具有更高的产氢效能和更加稳定的产氢效果,能够为厨余发酵产氢提供有利的保障。     

高浓度有机废液COD处理获取产业化沼气技术开发进展

广西壮族自治区每年排放的工业废水中的COD值高达70×10^4t以上。在引进和再创新日本UASB-TLP技术的基础上,进行了菌群筛选与优化、颗粒污泥最佳培养条件的选择和控制,并改进了厌氧罐体内部结构,解决了大量、快速培养厌氧颗粒污泥的技术问题,在中试规模下COD负荷达到25kg/（m^3·d）。产生了数量非常可观的沼气,为发展“产业化沼气”创造了条件。配以厌氧后段好氧发酵,酒精废液的COD值可较快地降至100mg/L以下。以COD计,我国工业和城市生活污水中所含有机物生物质能若全部加以处理和收集,则每年至少可产150×10^8m^3甲烷。     

SBBR法厌氧氨氧化的快速启动

采用92%的剩余污泥和8%的厌氧氨氧化颗粒污泥的混合接种策略,研究了序批式生物膜反应器(SBBR)厌氧氨氧化(ANAMMOX)工艺的快速启动。通过提高进水基质负荷和缩短水力停留时间(HRT)等首段,并在不除氧的条件下,经64 d实现了ANAMMOX的快速启动。稳定运行期间,NH₄⁺-N、NO₂^--N和TN去除率分别达到87%、99%和85.6%,总氮去除负荷高达1.49 kg/(m³·d),并且活性仍有提升的空间。研究发现,接种含有少量厌氧氨氧化菌(AnAOB)颗粒污泥的混合污泥能实现AnAOB的快速富集和ANAMMOX的快速启动。     

SBR反应器中好氧颗立污泥的培养

在SBR反应器中采用好氧/厌氧交替进行的方式和水力筛分的方法,将絮状的污泥培养成反硝化聚磷颗粒污泥.     

益生菌生产废水处理工程设计与运行

采用混凝沉淀法-升流式厌氧污泥床反应器-生物接触氧化法-缺氧-好氧活性污泥法组合工艺处理益生菌生产废水,处理规模500 m~3/d,原水COD 12 000~13 000 mg/L、BOD54 200~5 200 mg/L、NH3-N 150~200 mg/L,SS 300~500 mg/L,处理后出水水质满足《污水综合排放标准》(GB 8978—1996)表4规定的一级排放标准,即COD≤100 mg/L、BOD_5≤20 mg/L、NH_3-N≤15 mg/L、SS≤70 mg/L。该工艺运行费用低、管理简单方便、易于操作、无二次污染。     

低热-Na2CO3联合处理生物污泥释放碳源

针对剩余污泥溶胞效率低问题,开展低热-Na₂CO₃联合处理剩余污泥释放碳源的研究。结果表明,相对最佳试验条件下,Na₂CO₃投加量6.0 g/L、试验温度90℃、反应时间24 h,上清液中SCOD (溶解性化学耗氧量)、蛋白质和多糖浓度分别达11 781.78 mg/L、1 289.67 mg/L和537.81 mg/L。通过破解前后SEM照片可知,破解前初始污泥颗粒轮廓清晰,颗粒分明;破解后污泥颗粒表面明显被破坏,出现团聚现象。研究表明,采用低热-Na₂CO₃联合处理能够有效破解污泥,释放碳源。     

厌氧氨氧化的启动特性研究

厌氧氨氧化是最具潜力的脱氮技术之一。为探究厌氧氨氧化反应器启动过程中物质降解和胞外聚合物的变化,实验利用SBR反应器启动了富集ANAMMOX污泥的实验装置,测试启动过程中氮素的降解特征,胞外聚合物的变化规律。实验结果如下:(1)随着培养的进行,颗粒逐渐增大;(2)到124天时,氮素去除能力达到166.53 mg/(L·d)NH_4~+-N和219.01 mg/(L·d) NO_2~--N;(3)污泥EPS中蛋白质为主要成分,蛋白质的浓度随负荷的增加而阶梯式增涨。多糖含量变化不大,维持在20 mg/g以下。PN/PS值随负荷的增加而波浪形上升。     

基于氨氮的低曝气控制策略与应用效果分析

北京某市政污水厂采用基于氨氮的曝气控制策略,设定好氧池末端氨氮在1.0～2.5mg/L之间。在不加碳源、超设计水量负荷的情况下,好氧池末端氨氮日均值实际控制在0.15～2.78mg/L之间,总出水氨氮日均值最高为0.46mg/L。进水TN平均为51.0mg/L,出水TN平均值达到8.37mg/L,缺氧池出现反硝化吸磷反应,实现了高效脱氮除磷和低能耗运行。     

SBR循环周期对好氧颗粒污泥结构及稳定性的影响

研究不同SBR循环周期对好氧颗粒污泥物理结构及稳定运行的影响。SBR采用不同反应时间（3、4、6、12h/周期）运行,通过对MLSS、SVI、干密度、粒径、COD等指标的检测,研究颗粒污泥在不同运行周期下的结构变化及稳定性。以4h/周期运行的颗粒污泥粒径最大,大于0.8mm的占78.03%,污泥干密度最小117.58g/L;以3h/周期运行的颗粒污泥密度最大156.12g/L,粒径最小,大于0.8mm的占15.70%;以6h/周期运行的颗粒污泥有机物降解速率最高;以12h/周期运行10d左右颗粒污泥解体60%。     

生物制氢反应系统的启动负荷与乙醇型发酵

采用连续流搅拌槽式反应器(CSTR),以糖蜜废水为底物,研究了COD容积负荷对生物制氢反应系统启动过程中形成的乙醇型发酵产氢能力的影响。研究表明,在污泥接种量不小于6.24 gVSS/L、启动负荷为7.0 kgCOD/m3.d、水力停留时间(HRT)为6 h、系统pH、氧化还原电位(ORP)分别在4.0~4.3、-440~-470mV之间等条件下,可在30 d内完成乙醇型发酵菌群的驯化,实现生物制氢反应系统的快速启动。由不同启动负荷(3.0、7.0、10.0 kgCOD/m3.d)条件下形成的乙醇型发酵菌群,在相同的运行条件下其产氢能力存在着差异。当系统容积负荷为30 kgCOD/m3.d时,由启动负荷为7.0 kgCOD/m3.d条件下驯化形成的乙醇型发酵菌群比由启动负荷为3.0 kgCOD/m3.d条件下驯化形成的乙醇型发酵菌群产氢能力高56%。     

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.