共查询到19条相似文献,搜索用时 281 毫秒
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为解决海水直流冷却水系统中因忽略潮汐而带来凝汽器变工况特性与最佳真空求解的不准确性问题,以某电厂2×800 MW机组的海水直流冷却水系统为例,研究了考虑潮汐引起的海水水位变化对冷却水体积流量、机组微增功率和循环水泵耗电功率的影响,完善了凝汽器变工况和最佳真空的数学模型,得到凝汽器变工况特性的计算结果,并对考虑和不考虑潮汐影响2种情况下求解得到的凝汽器最佳真空进行了对比分析.结果表明:潮汐对凝汽器压力影响显著,且随着凝汽器进口水温的升高,这种影响增大;当2种情况下的循环水泵最优运行方式不同时,凝汽器最佳真空也不同,但考虑潮汐影响下的循环水泵最优运行方式总能保证机组在更好的经济效益下运行. 相似文献
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厂水泥熟料纯低温余热发电所用的是1×12 MW的机组,自投运以来凝汽器真空较长时间低于设计值运行,同时机组在运行中出现过凝汽器真空恶化的现象。经全面分析真空系统工作原理及设备运行工况,得出汽轮机真空系统不严密、射水抽气器工作不正常、循环水流量不足、循环水温升高、凝汽器传热端差大等是造成凝汽器真空低的主要原因。结合各种故障给出提高凝汽器真空的方法与措施,提高了真空值。 相似文献
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凝汽器真空是影响汽轮机经济可靠运行的重要参数,抽凝机实际运行在纯凝低真空工况。简述了凝汽器真空应达值和影响真空的主要因素,据此提出凝汽器的节能实践可通过改善抽凝机组的真空度,以达到综合煤耗率的最小化,降低发电成本,提高汽轮机运行的经济性。 相似文献
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论述了机组运行参数变化对凝汽器性能的影响,指出了主要参数对弟汽器真空的影响以及抽气设备对凝汽器工作的影响,给出了凝汽器变工况特性曲线。 相似文献
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为了提高直接空冷机组运行经济性,以冷端系统的变工况模型为基础,通过计算空冷凝汽器风机送风量增大时空冷机组发电功率与对应风机耗功功率的增量,得到直接空冷机组凝汽器最佳真空的确定方法.根据相似定律确定迎面风速对风机耗功的影响,并通过冷端系统数学模型的分析和简化得到机组背压与发电功率的关系,最终导出了不同环境温度和排汽热负荷下迎面风速对应的最佳真空.根据模型对某330Mw机组在变工况下的最佳真空进行了计算,结果表明:随着排汽量的增加或环境温度的升高,最佳真空及对应的风量都增加;当环境温度高于20℃时,环境温度对最佳真空的影响更加突出. 相似文献
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首先阐述循环水系统优化运行的目标值--最佳真空确定的原理;然后计算分析了凝汽器清洁情况对最佳真空的影响;最后利用凝汽器综合清洁系数来体现凝汽器水侧管壁脏污程度、汽轮机真空系统严密性对最佳真空的影响,提高了最佳真空的确定精度、得到的循环水系统优化方式更合理. 相似文献
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《Applied Thermal Engineering》2007,27(11-12):1799-1805
Heat and power integration can reduce fuel usage, CO2 and SO2 emissions and, thereby, pollution. In the simultaneous heat and power integration approach and including additional production, the optimization problem is formulated using a simplified process superstructure. Nonlinear programming (NLP) contains equations which enable structural heat and power integration and parametric optimization. In the present work, the NLP model is formulated as an optimum energy target of process integration and electricity generation using a gas turbine with a separator. The reactor acts as a combustion chamber of the gas turbine plant, producing high temperature. The simultaneous NLP approach can account for capital cost, integration of combined heat and power, process modification, and additional production trade-offs accurately, and can thus yield a better solution. It gives better results than non-simultaneous methods. The NLP model does not guarantee a global cost optimum, but it does lead to good, perhaps near optimum designs.This approach is illustrated by an existing, complex methanol production process. The objective function generates a possible increase in annual profit of 1.7 MEUR/a. 相似文献
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Navier—Stokes Computations of the Supersonic Ejector—Diffuser System with a Second Throat 总被引:3,自引:0,他引:3
The supersonic ejector-diffuser system with a second throat was simulated using CFD.An explicit finite volume scheme was applied to solve two-dimensional Navier-Stokes equations with standard κ-εturbulence model.The vacuum performance of the supersonic ejector-diffuser system was investigated by changing the ejector throat area ration and the operating pressure ratio.Two convergent-divergent nozzles with design Mach number of 2.11 and 3.41 were selected to give the supersonic operation of the ejector-diffuser system.The presence of a second throat strongly affected the shock wave structure inside the mixing tube as well as the spreading of the under-expanded jet discharging from the primary nozzle.There were optimum values of the operating pressure ratio and ejector throat area ratio for the vacuum performance of the system to maximize. 相似文献
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The aims of this study are to optimize the coupling of a low-cost offset paraboloidal dish, which concentrates direct solar irradiance with dual axes tracking component, and the fibre optic bundle (FOB), which transmits concentrated solar energy; to review previous studies on the transmission of concentrated solar energy via optical fibres (TCSEvOF) by classifying according to their purposes; to present a mathematical model for coupling symmetrical paraboloidal dish and FOB, and a modified model for optimum coupling of offset paraboloidal dish proposed in our study, taking into account the parameters of the dish and dispersion effect; to apply the models to symmetrical and offset paraboloidal dish under the same conditions; and to compare the annual output power obtained. Optical efficiency of the whole system was calculated as 68% in optimum condition, but it was found to be 63% for the system proposed. Overall system efficiency was found to be 59%. It was found that offset paraboloidal dish produced much more energy than the symmetrical one does when comparing under the same conditions. The difference of monthly average annual obtainable power was calculated as 0.82%. The monthly average annual power gained from the offset paraboloidal dish proposed was computed as 1041.6 kW to per square metre. 相似文献
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