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Fuzzy cascade control based on control's history for superheated temperature


To address the characteristics of the large delay and uncertainty of superheated temperature, a new cascade control system is presented based on control's history.


Dynamic behavior of superheated steam and ways of control


It is the first time that a phase compensation for real roots, i.e., the twin lead/lag loop which is facile for engineering applications, is used in superheated steam temperature control.


Moreover, a formula to calculate the setting parameters is presented, together with a practical example of its engineering application in superheated steam temperature control with singlestage attemperation in a power plant boiler.

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 Isolated desuperheater for turbine extraction of large steam turbines is a new technique to improve the thermal economy of the heat cycle.Why it can be improved? How much it improves the turbine heat rate? What is the effectiveness of adopting isolated desuperheater for various extrations? Which is better,Whether the isolated desuperheater in series or in parallel with the feed water heater In resolving these technical problems,qualitative ano analyses are carried out according to the principle of entropy increase.Under... Isolated desuperheater for turbine extraction of large steam turbines is a new technique to improve the thermal economy of the heat cycle.Why it can be improved? How much it improves the turbine heat rate? What is the effectiveness of adopting isolated desuperheater for various extrations? Which is better,Whether the isolated desuperheater in series or in parallel with the feed water heater In resolving these technical problems,qualitative ano analyses are carried out according to the principle of entropy increase.Under the direction of these qualitative analyses,and by means of Mr.F.L.Mas theories of "Functions of Steam Cycles" and "Equations for Optimum Enthalpy Rise",20 schemes are compared for two different classes of 300MW turbinegenerator sets,either with or without an extraction from the high pressure turbine.The conclusion recommends that isolated desuperheater in series with high pressure heater for higherly superheated extractions with their enthalpy rise properly increased is effective measure to improve thermal efficiency of large turbinegenerator sets as well as to save energy.  独立的抽汽冷却器是大型机组回热系统提高热效益的新技术。这项新技术为什么可以降低汽轮机组热耗?机组热耗可以降低多少?各级抽汽采用独立冷却器的效益如何?独立冷却器与高压加热器是串联还是并联好?对这些技术问题,本文应用熵增原理进行定性分析,并在定性分析的指导下,应用文献[2]提出的“循环函数”和“最佳分配方程”,对高压缸有无一级抽汽的两类30万千瓦机组热力系统,进行了20个方案的计算比较。综合这些分析比较,可以认为,过热度较高的回热抽汽采用串联的独立冷却器,适当加大该级给水焓升,是提高大型机组热效率、节约能源的有效措施。  In this article the method of calculation of flow deviation in the complex superheater connection systems frequently used in conventional large capacity utility boilers is given. The said complex systems include: (1 )the superheater arrangement in which the entire superheater system is divided into two paths and the superheated steam leaves at one end of the main header of the two paths, and ( 2 ) those in which the method of leadin and leadout of the superheater tube banks does not belong to the typical... In this article the method of calculation of flow deviation in the complex superheater connection systems frequently used in conventional large capacity utility boilers is given. The said complex systems include: (1 )the superheater arrangement in which the entire superheater system is divided into two paths and the superheated steam leaves at one end of the main header of the two paths, and ( 2 ) those in which the method of leadin and leadout of the superheater tube banks does not belong to the typical "Z", "U" or "L" arrangement, but instead several steam leads are arranged for leadin and leadout at the middle of the headers. Finally a simplified nornogram for the calculation of flow d2\'iation in typical systems of header arrangement is obtained with the help of a digital computor and presented in the paper.  本文给出了一般大容量电站锅炉中常用的复杂过热器连接系统的流量偏差计算方法,包括:(1)整个过热器系统分成两路而在两路的汇总处单侧引出过热蒸汽;(2)过热器管组的引入引出方式不属于典型的Z型、U型或L型等布置型式,而是用几根导汽管在集箱中部引入或引出。最后文中还列出了用电子计算机计算得出的典型集箱布置系统的流量偏差简化线算图。  Basic theory of thermodynamics has been employed here to approch a mathematical model of superheated steam enthalpy function with the aid of methods of higher mathematics. Formula of enthalpy value derived from this article with its allowance within the limit of the new international table. Its accuracy is high for industrial application in the interval 065 MPa, 27315107315K. The accuracy of function formulae of specific volume and specific entropy derived thereof are also high.  本文应用热力学基础理论,借助高等数学工具,对过热水蒸汽焓函数的数学模型进行了探索,导得在新国际骨架表允差内适用于0～65MPa、273.15～1073.15K的焓值公式,且具有工业应用足够高的精度。本文公式具有形式简单、精度高和适用范围广等特点,便于工程实用。   << 更多相关文摘 
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