过热汽温的动态特性与控制

Dynamic Behavior of Superheated Steam and Ways of Control

给出了过热器动态特性的简便计算方法。按过热器的结构和热力参数计算出单级和多级过热汽温的传递函数。与实测数据相比较,证实这种方法准确而且简便。首次提出在过热气温控制中,采用取实根的相位补偿,即2个串联的超前/滞后环节,在工程中实现很方便。经大量仿真试验证实,其过渡过程时间缩短1半左右,最大动态偏差缩减2-3倍。还给出整定计算公式及多种整定计算数据的取法,以及在一级喷水过热汽温控制的工程应用实例。该方法极大地改善了过热汽温控制品质,电站锅炉过热器可采用一级喷水减温,使过热器系统结构简化,设备投资减少。由于汽温控制品质大大提高,可把汽温控制系统的设定值定在稍高于额定值。在不影响机组运行安全性的同时,提高机组运行的经济性。

A simple way of calculating the dynamic behavior of superheaters is being presented, A comparison of actually measured data with transfer functions of single and multi-stage superheaters＇steam temperature, calculated in accordance with the superheater＇s structure and thermal parameters, verifies the accuracy of this method, which is moreover quite simple, Besides, it＇ s the first time that phase compensation for real roots is made use of in superheated steam temperature control, i.e. the application of twin lead/lag for two cascades. This method is facile for engineering application. Numarous simulation results show that the response time lapse is herewith reduced by half and maximal dynamic deviation is reduced by 2/3. Morevover, a formula for calculating setting values and a way of proper choice among a number of calculated setting values is presented, accompanied by a practical example of its engineering application in superheated steam temperature control with single stage attemperation. Application of this method can remarkably improve the quality of superheated steam temperautre control and makes it possible that one stage attemperation will be sufficient for superheaters of power plant boilers; herewith simplifying the superheater system and reducing investment. Because steam temperature quality is remarkably raised, the set values of the steam temperature control system can be raised somewhat above rated values and herewith also the operational economy, without impairing the set＇ s safety. Figs 4, tables 4 and refs 3.