共查询到20条相似文献,搜索用时 203 毫秒
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《工程热物理学报》2015,(4)
本文基于高温太阳能热化学等温法循环分解H_2O或CO_2制备H_2或CO,通过在其下游加入甲烷进行重整及部分氧化反应,在进行余热余气回收的同时实现了甲醇动力多联产,提出三种系统方案并进行了能耗及效率分析。结果表明,等温法同时分解水和CO_2的甲醇动力多联产系统,可以取消水煤气变换反应及CO_2的分离单元,进行合理的热回收后达到太阳能甲醇转换效率为30.52%,制取甲醇的净太阳能能耗为65.25 GJ/t,甲烷单耗为25.74 GJ/t。采用甲烷互补的甲醇动力多联产可取代超高温换热器以及甲醇合成过程的自备电厂,与仅有太阳能作为输入的高温太阳能热化学双温法制取甲醇相比,效率可提升两倍。 相似文献
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《工程热物理学报》2017,(7)
本文提出并研究了一种回收透平排气有效成分的新型功冷联产系统。该系统通过对高温高压过热氨水蒸气进行热能梯级利用和有效成分回收,实现了动力循环与制冷循环间能量和物质的双重耦合。经过部分冷凝后的透平排气中有效成分浓度明显提高,对这部分有效成分的回收可以有效增加系统制冷量。新系统等效作功效率为20.19%,比常规分产系统提高了44.32%,相对节能率为31.61%。与常规开式和常规闭式功冷联产系统相比,新系统等效作功效率提升幅度分别为7.28%和17.04%。通过研究能量传递与转换过程,阐明了系统的节能机理。新提出了平均能量品位差△A的概念,分析了系统对输入的利用情况和热力性能进一步提升的潜力。另外,还初步探索了系统中动力循环与制冷循环的耦合特性。 相似文献
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本文开拓性地提出了一种新型多种化石能源输入(煤和天然气)、多种产品输出(电力和化工产品)的多功能能源系统。该系统将天然气/水蒸气重整过程和煤的燃烧过程有机整合,用煤燃烧替代了传统重整过程清洁的燃料天然气和弛放气燃烧,实现了煤和天然气的综合互补利用;将甲醇生产系统与发电系统有机整合,实现了化工系统弛放气的梯级利用同时,对甲醇生产系统余热进行了更加有效的利用。研究表明生产相同量的甲醇和电,多功能系统比参比系统少消耗 20%的天然气。本文工作为煤和天然气综合高效利用提供了新途径. 相似文献
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《Heat Recovery Systems and CHP》1989,9(6):547-552
Gas turbine exhaust is usually relatively clean, especially the exhaust from natural gas turbines. The use of such gases to improve the overall thermal efficiency of a steam power plant has the advantage of reducing the cost of cleaning the equipment and reducing the maintenance costs of the heat recovery equipment used in the application.In this paper, two proposals for recovering the waste energy of the exhaust gases from a gas turbine unit, fuelled by natural gas at south Baghdad Power Plant (Iraq) are discussed. The proposals cover improvements to the thermal efficiency of a steam power plant installed near the gas turbine unit. The first proposal is to use the exhaust gases to preheat the feed water at four feed water heaters, in order to increase the power output. This arises because of the savings in the amount of steam extracted at a different level used for preheating the feed water line. The second proposal is to use the thermal energy in the exhaust gases to reheat the extracted stream, at five points at a high thermal potential, to increase the thermal gain at the preheating feed water line. This avoids the complexity associated with rejection of the extracted steam. The first roposal shows that a 1.22–14.9% saving in fuel consumption is achievable and the overall thermal efficiency of the steam power plant becomes 29–34% (at different gas turbine plant loads). The second proposal shows that a 2.3–7.35% saving in fuel consumption can be attained and the corresponding thermal efficiency will be 30.3–32%. 相似文献
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On the basis of the established irreversible simple closed gas turbine cycle model, this paper optimizes cycle performance further by applying the theory of finite-time thermodynamics. Dimensionless efficient power expression of the cycle is derived. Effects of internal irreversibility (turbine and compressor efficiencies) and heat reservoir temperature ratio on dimensionless efficient power are analyzed. When total heat conductance of two heat exchangers is constant, the double maximum dimensionless efficient power of a cycle can be obtained by optimizing heat-conductance distribution and cycle pressure-ratio. Through the NSGA-II algorithm, multi-objective optimizations are performed on the irreversible closed gas turbine cycle by taking five performance indicators, dimensionless power density, dimensionless ecological function, thermal efficiency, dimensionless efficient power and dimensionless power output, as objective functions, and taking pressure ratio and heat conductance distribution as optimization variables. The Pareto frontiers with the optimal solution set are obtained. The results reflect that heat reservoir temperature ratio and compressor efficiency have greatest influences on dimensionless efficient power, and the deviation indexes obtained by TOPSIS, LINMAP and Shannon Entropy decision-making methods are 0.2921, 0.2921, 0.2284, respectively, for five-objective optimization. The deviation index obtained by Shannon Entropy decision-making method is smaller than other decision-making methods and its result is more ideal. 相似文献
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The scale-dependent response of an instrumented full-scale wind turbine is studied under neutrally stratified conditions. The analysis is focused on the linkage between the incoming flow, turbine power output and foundation strain. Wind speed, measured from sonic anemometers installed on a meteorological tower, and foundation strain were sampled at 20 Hz, while the turbine power was sampled at 1 Hz. A wavelet framework and structure function are used to obtain cross correlations among flow turbulence, turbine power and strain across scales as well as to quantify intermittent signatures in both flow and turbine quantities. Results indicate that correlation between the streamwise velocity component of the wind flow and turbine power is maximised across all scales larger than the rotor radius for wind measured at the turbine hub height. The characteristic time lag associated with maximum correlation is shown to be consistent with the Taylor’s hypothesis for turbulent scales smaller than the separation between the meteorological tower and the turbine. However, it decreases with increasing scale size and diminishes to zero at scales on the order of the boundary layer thickness. Turbine power and strain fluctuations exhibited practically the same behaviour at scales larger than two rotor diameters. At those scales, the cross correlation between these quantities resulted ~0.99 and remains still over 0.9 at the scale of rotor radius. Below this scale, the correlation decreases logarithmically with scale. The strong linkage between power and strain for all the relevant scales would eventually allow the analysis of dynamic forcing on the foundation based on the power output. Intermittency on the flow is shown to be transferred and amplified by the turbine, leading to highly intermittent power output. 相似文献
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《Heat Recovery Systems and CHP》1988,8(5):433-443
Liquid hydrogen is expected to be an alternative to fossil fuel. In this study, the gas turbine cycle with the precooler and hydrogen turbine is proposed to utilize the cryogenic exergy contained in the liquid hydrogen effectively. Since the geometry of the precooler greatly affects the performance of the system, it is optimized to give the maximum specific work output and/or the maximum exergy efficiency. In addition, the mass flow rate of hydrogen in the precooler is not restricted to that used for combustion. The ratio α of hydrogen mass flow rate is introduced as a measure indicating the precooling effect. The surplus hydrogen is assumed to be consumed in the external gas turbine system. The effect of α on the output and the exergy efficiency of the total system is made clear. 相似文献
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轮背空腔-密封气对CAES向心涡轮变工况流动损失的影响 总被引:1,自引:0,他引:1
本文以国内首套MW级压缩空气储能(CAES)系统末级向心涡轮为研究对象,通过数值模拟分析了变工况条件下轮背空腔-密封气对等熵效率和流场结构的影响.结果表明:在求解中考虑轮背空腔-密封气结构能够使等熵效率数值解的偏差减小0.7%;随涡轮进口压力增加,轮背空腔泄漏流由叶片吸力面中部叶高区域逐渐向轮毂转移,流动损失先增加后减小;合理降低轮背空腔泄漏气体的轴向速度,能够减弱轮背空腔-密封气结构对等熵效率的负面影响,使向心涡轮在较宽的变工况范围内都保持高效运行. 相似文献
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In this paper, a wind energy conversion system is studied to improve the conversion efficiency and maximize power output. Firstly, a nonlinear state space model is established with respect to shaft current, turbine rotational speed and power output in the wind energy conversion system. As the wind velocity can be descried as a non-Gaussian variable on the system model, the survival information potential is adopted to measure the uncertainty of the stochastic tracking error between the actual wind turbine rotation speed and the reference one. Secondly, to minimize the stochastic tracking error, the control input is obtained by recursively optimizing the performance index function which is constructed with consideration of both survival information potential and control input constraints. To avoid those complex probability formulation, a data driven method is adopted in the process of calculating the survival information potential. Finally, a simulation example is given to illustrate the efficiency of the proposed maximum power point tracking control method. The results demonstrate that by following this method, the actual wind turbine rotation speed can track the reference speed with less time, less overshoot and higher precision, and thus the power output can still be guaranteed under the influence of non-Gaussian wind noises. 相似文献