共查询到19条相似文献,搜索用时 390 毫秒
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超临界和超超临界锅炉水冷壁的优化设计 总被引:6,自引:2,他引:6
阐述了超临界和超超临界锅炉水冷壁的优化设计,主要包括:下辐射区水冷壁采用内螺纹管,降低质量流速,准确掌握超临界流体热物性,减小工质焓增,减小热偏差和壁温偏差,降低局部热负荷,提高安全裕度等综合性措施。最低直流负荷优化选择综合考虑启动系统成本和变负荷运行范围以及对负荷快速变化的跟踪性能,以适应机组调峰。对1000MW超超临界锅炉垂直管屏水冷壁的流动特性进行了理论分析,强调应高度重视运行煤质变化的影响并严格监控水质。图5表1参7 相似文献
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针对1 000 MW超超临界机组锅炉内螺纹管垂直管屏水冷壁变压运行特性进行了理论分析.重点分析了低质量流速下的水冷壁热偏差对流量偏差的影响关系和内螺纹管传热特性以及直流锅炉水冷壁强制流动特性被自然循环特性部分低偿的流动特性. 相似文献
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超(超)临界压力锅炉垂直管屏水冷壁水动力与热偏差调整建议 总被引:2,自引:2,他引:0
垂直管圈超(超)临界压力锅炉一般都在水冷壁管入口安装节流圈,以调节工质流量,使其与对应区域的热负荷相匹配,但是该类型锅炉在投运后往往出现水冷壁节流圈结垢、水动力和热偏差,以致发生爆管.通过对水冷壁结构特点的分析,对爆管原因进行了研究,参考亚临界垂直管圈直流锅炉水动力调整经验,提出超(超)临界压力锅炉垂直管屏水冷壁系统改进和进行水动力调整的建议,即减少水冷壁管入口节流圈数量,在水冷壁管(屏)的入口安装调节装置以及加装水冷壁管屏的监视测点等. 相似文献
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通过机理分析和合理简化,建立了某电厂660 MW超超临界直流锅炉水冷壁系统的非线性移动边界动态数学模型,并对该锅炉在75%热耗率验收(Turbine Heat Acceptance,THA)工况和额定(Boiler Rated Load,BRL)工况下水冷壁系统的动态特性进行仿真,结果表明:各种扰动下水冷壁系统各参数的变化趋势均能通过机理分析给予合理解释;在不同的扰动输入下,水冷壁系统各参数的动态特性各异;当75%THA工况时,在进口焓值阶跃扰动下,蒸发段长度的动态响应存在超调;当75%THA工况和BRL工况时,在进口焓值阶跃扰动下,出口蒸汽比焓在其响应初期都存在逆向变化过程。研究工作加深了对660 MW超超临界直流锅炉水冷壁系统动态特性的认识,可为优化该型锅炉的设计、控制和运行以及电站仿真机的开发提供理论参考。 相似文献
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电站锅炉省煤器出口水温升高对过热器吸热的影响 总被引:2,自引:0,他引:2
讨论了某台200 MW燃煤自然循环锅炉省煤器改造后出口水温升高而造成的屏式过热器超温,根据锅炉锅筒欠焓计算与水冷壁产汽量计算,并结合炉膛换热及出口烟温计算,分析了省煤器出口水温与屏式过热器吸热量之间的内在联系。现行锅炉热力计算方法未考虑省煤器出口水温与炉膛内蒸发受热面产汽量的依赖关系,不能体现省煤器出口水温较大幅度变化对炉膛吸热量的影响。 相似文献
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超临界机组给水控制的任务是以中间点温度或焓值作为表征量,进而控制汽温和不同负荷下的给水量。中间点焓值概念明确、灵敏度高,并且由于工质大比热特性,故应用中间点焓作为表征量更科学。对于直流锅炉给水的吸热、蒸发和过热之间没有明确分界的复杂对象,机理建模已难于适用。而以输入输出数据提供的信息来建立热工对象模型的系统辨识方法则显出优越性。依据某超临界600MW机组DCS数据图,应用MATLAB系统辨识建立了中间点焓值-给水量热工对象数学模型并降阶简化。最后以一仿真实例验证了模型的有效性、准确性及工程应用价值。 相似文献
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根据国际新工业标准IAPWS—IF97公式计算的数据,利用最小二乘法的原理,在饱和蒸汽的工业锅炉压力等级系列适用范围内,以绝对压力p为变量,拟合出干蒸汽焓h''、干饱和蒸汽比容v''、饱和水焓h'、汽化潜热r(△hv)、饱和水比容v'的函数表达式,最终给出由给水压力pgs和给水温度tgs表示的给水焓hgs给水密度ρgs表达式,这些函数表达式,可用于饱和蒸汽工业锅炉性能试验、热力统计、能源审计等的计算,具有精度高,适用范围大,便捷、实用的特点。 相似文献
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R. Harish E.E. Subhramanyan R. Madhavan S. Vidyanand 《Applied Thermal Engineering》2010,30(14-15):2051-2057
In sea water based once through cooling water system for power plants, sea water is pumped through the condenser and the return hot water is let back to sea. The cooling water pumps (CWP) in power plants generally operate at constant speed, pumping variable quantities of water depending on the tide level in the sea. The variable flow causes variation in condenser back pressure resulting in changes in the turbine cycle heat rate. If the pump speed is controlled using a variable frequency drive (VFD) to maintain design flow irrespective of the tide level, the CWP power consumption can be reduced compared to the case with constant speed CWP. However, the turbine cycle heat rate benefit that could have accrued at tide levels above the pre defined level (for fixing the CWP head) with constant speed CWP would have to be sacrificed. This paper provides a theoretical model with a typical case study to establish viability of providing VFD for CWPs in power plants with sea water based once through condenser cooling water system. 相似文献
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《Applied Thermal Engineering》2002,22(1):41-59
In this paper, the mathematical and physical models governing the flow, mass and heat energy of moist have been set up for an evaporative natural draft cooling tower. The models consider the effect of non-spherical shape of water drops on the flow, heat and mass transfer. Experimental data has been adopted to validate the numerical scheme. Average difference between the measured and the predicted outlet water temperature is 0.26°C. Distributions of the velocity components of the moist air, density, pressure, enthalpy and moisture content, the water temperature and its mass flux have been predicted. The simulation shows that some recirculation exits under the lower edge of the shell, where the air enthalpy, temperature, humidity and moisture content are higher, but the density is lower. The simulation also proves that the main transfer processes take place in the fill region where the percentage of latent heat transfer is predicted as 83%. However, about 90% of the heat energy is transferred via evaporation in the rain region although the total heat transfer rate there is very small compared to the fill region. Hourly performance of a natural draft cooling tower under the meteorological condition of Singapore has also been predicted. 相似文献