共查询到18条相似文献,搜索用时 234 毫秒
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由凝结水泵出口引出部分凝结水进入再生热交换器,吸收蒸汽发生器排污热量,是目前蒸汽发生器排污利用较普遍的回收热量方式。以某990MW核电机组为例,在蒸汽发生器排污量和排污参数一定的情况下,分别计算凝结水抽取份额、排污热量回收利用方式的不同对循环热效率、二回路管道热效率和全厂热效率的影响。结果表明,随着凝结水抽取份额的增加,循环热效率降低,而二回路管道热效率提高,当二者的相对变化量相等时,全厂热效率达到峰值;同时,考虑到排污水化学处理系统的安全性要求,确定蒸汽发生器排污热量回收利用的最佳方案:凝结水抽取份额为2.5%,且排污热量回收到除氧器。 相似文献
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为研究抽汽背压式汽轮机(BEST)系统超超临界1 000 MW二次再热蒸汽机组参数的选取,基于某电厂二期2×1 000 MW超超临界机组扩建项目,建立1 000 MW超超临界高效二次再热蒸汽机组的设计计算,使用EBSILON软件建立完整的热力系统模型,得出主蒸汽温度、再热蒸汽温度、主蒸汽压力、再热蒸汽压力和锅炉效率等参数对BEST系统的影响规律。研究结果表明:对于12级回热的BEST系统来说提高主蒸汽的温度比提高主蒸汽的压力更能提高系统的发电热效率;BEST系统最佳工况点的再热蒸汽压力是15.028 MPa/4.079 MPa;锅炉效率变化范围在85%~95%时,随着锅炉效率变化1%,系统发电热效率随之变化0.51%。 相似文献
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针对大容量高参数机组锅炉出现的高度增加、管道增长及阻力损失增大等问题,提出一种新型沉降式电站锅炉设计,使汽轮机平台和锅炉过热器、再热器平台在同一水平面,从而大幅度缩短主蒸汽、再热蒸汽冷段和热段管道长度,对管道长度变化带来的阻力损失、机组热经济性及发电成本的变化进行了分析.结果表明:沉降式电站锅炉的管长明显缩短,当主蒸汽、再热蒸汽冷段和热段的管道长度均减少120m时,电厂热效率提高0.18%,煤耗率降低1.044g/(kW·h),管材初投资减少约6 500万元;以年利用小时取5 294h,煤价为600元/t计算,年节煤6 093t,节约燃料成本约366万元/a,降低发电成本0.28分/(kW·h). 相似文献
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文章以上海某垃圾焚烧发电厂为例,针对其在额定工况与变工况下的热力特性及其参数变化规律进行研究。研究结果表明:在额定工况下,该垃圾焚烧发电厂日处理垃圾6 000 t,其额定功率和发电效率分别为50 MW和28.49%;在变工况条件下,垃圾中的C含量是影响垃圾焚烧发电热力参数的主要因素;11月垃圾的C含量(30.23%)最高,相应的系统总输出功高达61.45 MW,热效率为28.93%;8月垃圾的C含量(24.91%)最低,相应的系统总输出功(47.35 MW)也最低,热效率为28.66%;蒸汽流量的增加会提高主蒸汽压力,当主蒸汽压力达到7.9 MPa时,系统总输出功达到最大值54.97 MW,热效率为30.82%,当主蒸汽压力超过7.9 MPa时,系统总输出功与热效率开始下降;垃圾流量减少会导致发电系统的总输出功和热效率降低,当垃圾流量减小至额定工况的60%时,系统总输出功计算值与设计值的相对偏差可达到8.7%。 相似文献
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This paper provides fundamental principles to study the thermodynamic performance of a new screw expander–based solar thermal electricity plant. While steam turbines are generally used in direct steam generation solar systems without admitting fluid in two-phase conditions, steam screw expanders, as volumetric machines, can convert thermal to mechanical energy also by expanding liquid-steam mixtures without a decline in efficiency. In effect, steam turbines are not as competitive as screw expanders when the net power is smaller than 2 MW and for low-grade heat sources. The solar electricity generation system proposed in this paper is based on the steam Rankine cycle: Water is used as both working fluid and storage, parabolic trough collectors are used as a thermal source, and screw expanders are used as power machines. Since screw expanders can operate at off-design working conditions in several situations when installed in direct steam generation solar plants, studying expander performance under fluctuating working situations is a crucial issue. The main aim of the present paper is to establish a thermodynamic model to study the energetic benefits of the proposed power system when off-design operating conditions and variable solar radiation occur. This entails, first and foremost, developing overexpansion and underexpansion numerical models to describe the polytropic expansion phase, which considers all the losses affecting performance of the screw expander under real operating conditions. To assess the best operating conditions and maximum efficiency of the whole power system at part-load working conditions under fluctuating solar radiations, parametric optimization is then improved in a wide range of variable working conditions, assuming condensation pressures of water increasing from 0.1 to 1 bar, under an evaporation temperature rising from 170°C to 300°C. 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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抽汽压损对机组热经济性影响的通用计算模型 总被引:5,自引:1,他引:4
经过严格的数学推导,证明了抽汽压损对热经济性的影响等同于抽汽压损引起的加热器出口水焓和疏水焓变化对热经济性影响的线性叠加。根据热力系统热经济性分析的基本方程,针对不同型式的加热器,计算了疏水焓对汽轮机作功量和锅炉吸热量的影响。得出了分析疏水焓变化对热经济性影响的通用计算模型。结合已建立的加热器出口水焓对热经济性影响的通用计算模型,推导了抽汽压损对机组热经济性影响的通用计算模型。该模型具有通用性强,适于程序化的特点。算例验证了该方法的正确性。 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