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《锅炉技术》2016,(3)
二次再热是超超临界燃煤发电机组节能减排重要方向。以我国首台二次再热机组为对象,依据热力学分析法,建立了热力系统分析的数学模型,研究了该超超临界机组及主要部件的效率和损失,讨论了负荷变化的影响。结果表明:二次再热机组TMCR工况下效率为45.9%,高于同等级的一次再热机组,其中锅炉效率为55.3%,汽轮机效率为88.1%。在机组损失分布中,锅炉损率最大,占机组的84.1%,其中以燃烧损失和传热损失为主。对于回热系统,高压加热器效率高于低压加热器。变负荷时,随着负荷的增加,锅炉和回热系统效率有所提高,同时锅炉损率有所降低,汽轮机损率有所升高。 相似文献
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根据热经济性指标和的物理意义,定义锅炉效率、机组效率、发电煤耗率的数学计算式;由小扰动理论和微分理论,当抽汽压损变化时,在热力系统汽水分布方程的基础上详细推导抽汽量变化与不同类型加热器出口水焓与疏水焓的微分关系式;根据锅炉效率、机组效率、发电煤耗率的数学计算式,推导锅炉效率、机组效率、发电煤耗率变化与抽汽量的微分关系式。结合N1000-25/600/600机组,定量分析抽汽压损变化对锅炉效率、机组效率、发电煤耗率的影响,为有效分析机组经济性提供理论依据。 相似文献
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煤炭一直以来都是中国最主要的一次性能源,相应地,燃煤锅炉也占有电力市场绝大部分份额。燃煤锅炉存在诸多能量损失途径,能量转换效率较低。系统地分析燃煤锅炉的热力性能非常必要。是热力学第二定律中的一个重要概念,它不仅能反映能量的数量,更能反映能量的品质。基于概念,对某600MW超临界燃煤锅炉模型进行了详细的分析,综合考虑物理和化学,计算了系统的损失、耗散等参数,对锅炉的设计、优化提供了可靠依据。 相似文献
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为揭示直接空冷机组热力系统的不可逆损失的机理和挖掘其节能潜力,对600MW直接空冷机组的热力系统进行分析和节能评价。结果表明:600MW直接空冷机组的目的效率为39.08%,总损失占60.92%。凝汽器的损系数为6.11%,而相同容量水冷机组的凝汽器损系数仅为2.23%,因此,必须对凝汽器采取节能措施,提高直接空冷机组的整体效率。 相似文献
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以随时空变化的环境温度(即动态基准温度)为基准点,对国内300 MW亚临界机组、600 MW及1 000 MW超临界机组回热系统的相关值进行了计算,在此基础上利用火用效率矩阵方程对回热系统加热器的效率进行了计算,分析了动态基准温度对回热系统加热器效率变化影响:随着基准温度升高,各加热器效率均降低,而抽汽压力越低效率降低的越多,各机组8号加热器效率降低的最大;对于各机组的8号加热器,当△Tjz=20℃时,△η分别等于-37.12%(300 MW机组)、-32.6%(600 MW机组)、-20.51%(1 000 MW机组),随机组容量增大呈现出降低的趋势。这可为回热系统乃至整个机组分析的动态基准点的选择提供参考。 相似文献
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基于成本理论建立了热力系统局部成本分析通用模型及火电机组热力系统成本分布的通用矩阵方程,并对某600MW机组的热力系统进行实例计算与分析,得到了额定工况下独立流的单位成本.结果表明:该方程构造规范,适用于各种不同的热力系统,可以用于分析热力系统中存在的共性规律;对于具体的热力系统,通过将一些必要的矩阵元素代入方程中,可得到独立流的单位成本和单位成本的分布规律,为机组的节能降耗提供指导;如果对方程进行进一步的微分运算分析,还可求出一些因素变化对单位成本影响的敏感度. 相似文献
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In the present work, exergy analysis of a coal‐based thermal power plant is done using the design data from a 210 MW thermal power plant under operation in India. The entire plant cycle is split up into three zones for the analysis: (1) only the turbo‐generator with its inlets and outlets, (2) turbo‐generator, condenser, feed pumps and the regenerative heaters, (3) the entire cycle with boiler, turbo‐generator, condenser, feed pumps, regenerative heaters and the plant auxiliaries. It helps to find out the contributions of different parts of the plant towards exergy destruction. The exergy efficiency is calculated using the operating data from the plant at different conditions, viz. at different loads, different condenser pressures, with and without regenerative heaters and with different settings of the turbine governing. The load variation is studied with the data at 100, 75, 60 and 40% of full load. Effects of two different condenser pressures, i.e. 76 and 89 mmHg (abs.), are studied. Effect of regeneration on exergy efficiency is studied by successively removing the high pressure regenerative heaters out of operation. The turbine governing system has been kept at constant pressure and sliding pressure modes to study their effects. It is observed that the major source of irreversibility in the power cycle is the boiler, which contributes to an exergy destruction of the order of 60%. Part load operation increases the irreversibilities in the cycle and the effect is more pronounced with the reduction of the load. Increase in the condenser back pressure decreases the exergy efficiency. Successive withdrawal of the high pressure heaters show a gradual increment in the exergy efficiency for the control volume excluding the boiler, while a decrease in exergy efficiency when the whole plant including the boiler is considered. Keeping the main steam pressure before the turbine control valves in sliding mode improves the exergy efficiencies in case of part load operation. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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随着深空探测技术的进步,空间核动力越来越成为载人航天任务的理想选择,将双模式空间核动力推进系统应用于航天推进系统已成为一种新的趋势。基于空间核能液态金属朗肯循环,提出一种新型的双模式核热推进系统,并对该推进系统发电模式下的液态金属朗肯循环进行了性能分析。利用能量分析和?分析的方法对双模式核热推进系统下的朗肯循环进行热力计算,得出各部件的能量损失和?损,找出损失最大的部件并分析原因,取不同的空间环境温度研究其对?损和?效率的影响,为系统的进一步优化提供理论依据。 相似文献
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采用平衡分析法,分别对小型热电联产系统和分散锅炉房供热系统进行了流分析,把两者计算所得效率作一对比,从而得出热电联产系统是取代分散锅炉房供热的节能措施之一。同时还对热电联产系统内各环节中的流损失进行计算,得出各热力设备的效率,找出系统用能不合理的主要薄弱环节,为今后设备的工艺过程改进指出了方向。 相似文献
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应用能量平衡和(火用)分析方法,对小龙潭火力发电厂300MW机组热力系统能量转换过程进行了定量计算,分析了各个单元的能量有效利用及损失情况,指出了损失的主要部位和原因.结果表明:热量损失主要发生在凝汽器单元,凝汽器散失到周围环境中的热量为411.28 MW,占输入热量的51.57%,锅炉单元散失的热量为52.96 MW,占输入热量的6.64%,汽轮机单元散失的热量为20.40 MW,占输入热量的2.56%;(火用)损主要发生在锅炉单元,锅炉、汽轮机和凝汽器单元的(火用)损分别占输入(火用)的67.78%、18.54%和13%;锅炉中燃料燃烧及大温差传热是整个系统不可逆的主要原因;不同工况下每个单元的(火用)损和(火用)效率会随着环境温度适度改变,但同一工况下机组总的(火用)效率不随环境温度变化. 相似文献
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Energy and exergy analysis were carried out for a combined‐cycle power plant by using the data taken from its units in operation to analyse a complex energy system more thoroughly and to identify the potential for improving efficiency of the system. In this context, energy and exergy fluxes at the inlet and the exit of the devices in one of the power plant main units as well as the energy and exergy losses were determined. The results show that combustion chambers, gas turbines and heat recovery steam generators (HRSG) are the main sources of irreversibilities representing more than 85% of the overall exergy losses. Some constructive and thermal suggestions for these devices have been made to improve the efficiency of the system. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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基于火(用)分析法和矩阵算法,建立了压水堆核电机组热力系统的通用火(用)损分布矩阵方程,并以某900MW压水堆核电机组为例进行了计算分析,得到了额定工况下热力系统及设备的焖损分布规律.结果表明:反应堆的焖损失最大,占核能总火(用)的50.85%,其次为汽轮发电机、蒸汽发生器和凝汽器,分别占核能总火(用)的6.17%、3.2%和2.55%;矩阵方程较常规火(用)分析法具有构造简单、矩阵元素填写法则简便、物理意义明确和规律性强等优点;利用该方程便于开发出相应的计算程序,进而为核电机组节能潜力挖掘和故障诊断提供依据. 相似文献
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The objective of this paper is to perform the energy, exergy and exergoeconomic analysis for the Hamedan steam power plant. In the first part of the paper, the exergy destruction and exergy loss of each component of this power plant is estimated. Moreover, the effects of the load variations and ambient temperature are calculated in order to obtain a good insight into this analysis. The exergy efficiencies of the boiler, turbine, pump, heaters and the condenser are estimated at different ambient temperatures. The results show that energy losses have mainly occurred in the condenser where 306.9 MW is lost to the environment while only 67.63 MW has been lost from the boiler. Nevertheless, the irreversibility rate of the boiler is higher than the irreversibility rates of the other components. It is due to the fact that the combustion reaction and its high temperature are the most significant sources of exergy destruction in the boiler system, which can be reduced by preheating the combustion air and reducing the air–fuel ratio. When the ambient temperature is increased from 5 to 24°C, the irreversibility rate of the boiler, turbine, feed water heaters, pumps and the total irreversibility rate of the plant are increased. In addition, as the load varies from 125 to 250 MW (i.e. full load) the exergy efficiency of the boiler and turbine, condenser and heaters are increased due to the fact that the power plant is designed for the full load. In the second part of the paper, the exergoeconomic analysis is done for each component of the power plant in order to calculate the cost of exergy destruction. The results show that the boiler has the highest cost of exergy destruction. In addition, an optimization procedure is developed for that power plant. The results show that by considering the decision variables, the cost of exergy destruction and purchase can be decreased by almost 17.11%. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献