In deep water

Continuing his column on offshore wind, Adam Westwood from energy analysts Douglas-Westwood Ltd, looks at how offshore wind farms will be increasingly located in deeper waters further from shore, and what the effects of this trend will be.     

Ten MVA superconducting generator development: status at the end of1989

A progress report and some initial results from the experimental program in superconducting generators at the Massachusetts Institute of Technology (MIT) are provided The 10 MVA generator developed at MIT was to demonstrate a number of advanced concepts. These included a fully cold rotor, a cryogenic system with built-in reserves for rapid recooling following serious electrical transients, a two-stage damping and shielding system with a damping resistor tailored to good dynamic performance, a field winding structure which allows for full fault torque without straining the field winding conductors, a limited voltage gradient armature winding, and a monolithic armature structural system that provides both rigid support and good electrical isolation. The generator was completed in 1985, and experimentation has been carried out since then. The basic electrical parameters have been verified through low-level steady-state no-load and synchronous impedance tests, and sudden short-circuit and sudden open-circuit transient tests     

Investigations of deep resistivity structures at the Wairakei geothermal field

The Wairakei geothermal field was the proving ground for the use of electrical resistivity methods for geothermal exploration. At this site it was first demonstrated that a large contrast in resistivity existed between geothermal ground and the cold surroundings. Within the top 500 m of the geothermal field, low-resistivity (5–10 Ωm) reflects the effects of both the hot saline water in the pore spaces and the conductive rock-matrix. The first surveys at Wairakei used a Wenner array (a ∼550 m) to measure the resistivity values along tracks throughout the field; contour maps of the resistivities were used to estimate the lateral extent of the geothermal waters at a few hundred metres depth. In the late 1960s the Wenner array was superseded by the Schlumberger array (AB/2 = 500 m and 1000 m), which enabled deeper penetration and better definition of the extent of the geothermal waters. These early surveys showed that the bounds of the geothermal waters were often sharp, leading to the concept that a ‘resistivity boundary’ could be defined for New Zealand's liquid-dominated geothermal fields. As new methods of measuring electrical structure with greater precision became available, Wairakei was often chosen as the testing ground.     

多年调节水库年末水位研究

建立了预测多年调节水库年末水位的ANN预测模型,针对GA、BP算法的优缺点,运用GA-BP算法求解网络模型.通过黄河龙羊峡水库实例计算证明,该方法可为水库调度提供一定依据.     

600 MW超临界锅炉尾部对流受热面积灰监测研究

为实现电厂按需吹灰,基于热平衡原理选取污染率作为积灰监测指标反映受热面的积灰程度,针对尾部对流受热面建立积灰监测模型并形成污染率计算流程.以某台600 MW超临界变压运行直流炉为实施对象,对尾部低过、低再及省煤器三个受热面进行污染率计算分析,结合积灰监测结果和安全经济性原则对尾部受热面的吹灰方式进行动态调整,并进行了3...     

大容量储能电站在输电网送端应用分析评估

受国家能源政策鼓励,新能源发展势头不减,占电网总装机的比例不断增加,但受网架结构薄弱、系统调峰、电压稳定等因素制约,新能源面临的输送能力、调频调峰、电力电量消纳和系统稳定等问题日益突出。针对储能电池的特性,研究提出了在输电网送端建设6 MW大容量储能电站的总体技术方案,对工程应用的投资收益进行了分析评估,对运营经济性进行了测算,为新能源基地电力消纳提供了新的技术实现途径。     

陕西小水电世纪末的回眸与展望

５０ 年来,陕西小水电及电气化事业得到了长足的发展,为工农业生产和贫困地区脱贫致富发挥了积极作用。本文对５０ 年的发展历程作以回顾,总结基本经验并提出新世纪小水电发展的方针     

Numerical investigation of production behavior of deep geothermal reservoirs at super-critical conditions

Numerical simulations have been performed to predict pressure transients in deep geothermal reservoirs at sub- and super-critical temperatures. First, pressure drawdown and buildup tests of reservoirs with different initial conditions were simulated. The calculated pressure responses are dominated by non-linear changes of fluid kinematic viscosity and compressibility. The pressure of a super-critical zone is shown to cause complex behavior. Short- and long-term production tests in both unbounded and bounded reservoirs were then simulated. Unbounded and bounded reservoirs exhibit very similar short-term production behavior near or above the critical temperature (375–400°C). Unbounded reservoirs of low transmissivity (kh = 1 darcy-meter) exhibit long-term production behavior that depends on whether the reservoir is sub-critical (300–375°C) or super-critical (400°C); substantial increases in flowing enthalpy and declines in feedpoint pressure occur at early times in the super-critical reservoir.     

Characteristics of Compression Wave Caused by Reflection of Expansion Wave at Open End of Tube

When an expansion wave propagated along a constant area straight tube reaches at the open end, the negative impulsive wave and the compression wave are formed by the emission and reflection of expansion wave. The negative impulsive wave is emitted toward the surrounding area and causes an impulsive noise like the sonic boom. The compression wave propagates in the tube toward the upstream and may cause the impulsive noise at the surrounding area of tube portal. With the advance of industrial engineering, it seems that the discharging of the expansion wave will become important problems. In this study, the experimental and numerical investigations are carried out using the shock tube and the TVD numerical method. The formation process of compression wave near the open end, the relationship with the compression wave and the expansion wave and the characteristics of compression wave are discussed.     

JZ-7型制动机双端操纵一个中继阀的制动系统

介绍在DF7C、DF7G型机车上保持JZ-7型制动机性能不变、机车操纵方式不变的情况下,由原来的双端操纵使用2个中继阀改为双端操纵使用1个中继阀方案的制动系统工作原理,并把相应各阀移到司机室外,方便机车的使用、检修和制造。     

齿轮箱轴端唇形密封结构的最大密封水压仿真研究

为了确保船舶齿轮箱水下密封可靠,开展船舶齿轮箱轴端唇形密封结构的最大密封水压研究。首先,进行齿轮箱轴端唇形密封结构的静力学仿真,得到了过盈量为0.5 mm条件下唇形密封和旋转轴之间的接触宽度和平均接触压力,经进一步计算得到了唇形密封结构的生热量。在此基础上,进行了唇形密封结构的热力学有限元仿真分析,获得了过盈量为0.5 mm时唇形密封结构最高温度随水压载荷的变化规律。最后,以150 ℃为最高温度上限,仿真获得了唇形密封结构的最大密封水压为0.035 MPa,并进行了输出轴端最大密封水压的试验验证,验证了仿真获得的最大密封水压结果的正确性。研究结果表明：在唇形密封与旋转轴过盈量为0.5 mm的条件下,唇形密封结构的最高温度与水压呈正相关关系。     

In situ burning via towed boom of oil spilled at sea

Operational guidance for the efficient use of combustion in the cleanup of a surface oil film, formed as a result of a spill at sea, is sought by approximate analysis. In remediation by burning, the spilled oil itself provides the energy for its cleanup. Attention is focused on situations holding relative ly far from the source of the spill and/or relatively long after the spill: the oil is taken to have so dispersed that the thickness of the film is on the order of a few millimeters. Under such conditions, the oil film is unlikely to burn without the use of multiple towed booms, each boom spreading its already-ignited, localized fire to continuously collected, previously unignited portions of the oil film. A simple, quasisteady, two-dimensional analysis suggests efficient values for the tow speed and the tow-line length as functions of such parameters as the oil density, oil-film thickness, oil burn/evaporation rate, etc. The analysis leads to specific suggestions for apparently unreported laboratory experiments that may be informative prior to at-sea operation.     

Effectiveness of evacuating combustible gases by two parallel expellers closely coupled at one end of a gas pipeline

Expeller performance has been formulated in terms of its capability to create suction pressure at the throat. This formulation has been used to assess the effectiveness of evacuating combustible gases from a pipeline section from one end using dual expellers mounted in parallel on two adjacent blow-down stacks. A general formulation was derived to address any situation of asymmetry in the stack resistance, asymmetry in the expellers' power as well overall pipeline resistance to suction flow. Solutions of the closed-form equations were obtained and presented on performance graphs showing the ratio of the suction flow using dual expellers to that using either one in a single mode. It was found that there are conditions at which expelling with dual expellers exceed that of either expeller operating alone. It was also shown that when asymmetric expellers are used, where one expeller is more powerful than the other, the benefits of using two expellers is realized up to a limiting degree of asymmetry, beyond which the weaker expeller could be stalled and then reverse flow.     

不同供热形式末端性能研究

对北京某高校办公室进行模拟研究,当采用地板辐射、散热器以及毛细管网吊顶辐射3种不同形式的供热末端时,分别研究室内温度的垂直分布以及水平分布,并结合实际工程对3种不同形式末端的经济性进行分析,从室内温度分布和经济性等方面对3种不同形式末端进行对比研究。     

Influence of water–rock interactions on fracture permeability of the deep reservoir at Soultz-sous-Forêts, France

Circulation of geothermal fluids through granitic fractured reservoirs leads to chemical reactions, modifying the porosity and permeability of the rock mass. FRACHEM, a thermo-hydraulic-chemical coupled computer code, was developed specifically to predict changes in the geothermal reservoir of the Soultz-sous-Forêts Enhanced Geothermal System (EGS) located in Alsace, France. This code can simulate fluid–rock interactions and determine the dissolution/precipitation reactions of eight minerals in the Soultz granite (i.e. carbonates, pyrite, silicates and aluminosilicates). Numerical simulation results of long-term fluid circulation through the 5000-m deep Soultz reservoir are comparable to those determined for the shallow reservoir and confirm the role played by carbonates in the evolution of reservoir porosity and permeability. Moreover, experiments with FRACHEM in simulating short-term fluid flow during hydraulic and/or chemical stimulations have demonstrated that the code could prove an efficient tool in reservoir engineering and management.     

Fast breeder reactors: the end of a myth?

Only very optimistic views of the progress of FBR technology allow one to envisage its competitiveness on a time horizon of 40–50 years. This might occur in the improbable context of a trebling or quadrupling of the price of uranium. Even in that case the benefits of electricity production by FBRs would not compensate for the enormous expense of the necessary R&D and eventual commercialization of this new nuclear system. However these considerations seem minor when compared to the economic obstacles presented by plutonium reprocessing from LWRs. Investment in the plutonium associated with the FBR will possibly be more expensive than the actual construction costs.     

AWEA predicts strong end to 2003

The American Wind Energy Association (AWEA) has reported that the U.S. looks likely to install up to 1600 MW of new wind power in 2003. While the outlook for the balance of the year is strong, AWEA warned that the wind industry's future beyond year's end will be strongly influenced by whether Congress extends the wind production tax credit (PTC) scheduled to expire at the end of 2003. According to AWEA's quarterly assessment of the wind energy market, the wind project developments that are underway could increase the cumulative total of U.S. installed wind capacity to over 6000 MW. That level of wind capacity will be able to produce approximately 16 billion kWh of pollution-free electricity, enough to serve 1.57 million average U.S homes. In the past month or so, a number of large projects have been announced that will increase the year-end total. AWEA Executive Director Randall Swisher commented, ”We see more reason for optimism than we did three months ago. The market appears to be firming as the end of the year draws nearer.” Developers are pushing to complete projects by the end of the year in order to qualify for the PTC. A quick extension of the credit is urgently needed, Swisher said, to ensure that the momentum gained toward industry growth is not lost as it has been in the past when the credit expired. A three-year extension of the PTC is included in both the House and Senate versions of comprehensive energy legislation now pending in Congress. Swisher also called on energy bill conferees to support Senate-passed provisions that would establish a national Renewables Portfolio Standard (RPS) requiring that 10% of the nation's electricity come from renewable energy sources by 2020 and a Small Turbine Investment Credit for homeowners who install residential wind machines. www.awea.orgThis is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news.     

Cu/In deposited at room temperature: morphology,phases and reactions

Bilayers of a slightly copper-rich composition of copper and indium deposited (in that order) at room temperature by vacuum evaporation, electroplating, and r.f. sputtering, were analyzed by MeV ⁴He backscattering spectrometry, scanning electron microscopy and X-ray diffraction before and after thermal annealing at 400 °C in vacuum. The surface morphology of as-deposited samples is roughest for evaporated samples and smoothest for samples deposited by sputtering with low r.f. power. All as-deposited samples contain copper and indium phases and the metastable CuIn compound. After 1 h at 400 °C, this metastable phase and that of copper disappear and are replaced by some copper-rich compound (Cu₉In₄, Cu₇In₄) in all cases. Simultaneously, the surface morphology smooths out considerably for the initially rough samples. Bilayers of various Cu/In compositions were also prepared. The results are consistent with the absence of stable compounds outside the 26–38 at.% indium range, as indicated by published phase diagrams.