基于PLC的乏汽增压系统控制技术

Control Technology of Exhaust Steam Boosting System Based on PLC

现有的控制技术增压值小、控制适应能力差,为此,本文研究了基于PLC的乏汽增压系统控制技术。首先,分析系统的性能,以系统输入参数作为压缩装置的设计参数,控制燃烧室的温度为定值;其次,通过计算流量与燃烧室温度的关系,在稳定工况下建立动力系统的计算模型;再次,在机组启动过程中,使预热蒸汽进入MSR装置进行再热,以有效分离饱和蒸汽中的水分;然后,设定并调节再热器管板温度与抽汽温度差值,利用光纤通信将PLC的数据传输到中控设备,通过PID输入设定频率以控制增压泵;最后,在旁通阀供水后,等待水压较低时,通过开启增压泵提升水压,完成对机组的控制运行。实验结果表明,当温度达到150℃时,实验组的低温蒸汽增压可达到0.4 MPa,有效提高了蒸汽的压差,改善了增压系统的控制适应能力。

The existing control technology has a small boost value and poor control adaptability,therefore,this paper studies a PLC-based control technology for exhaust steam boost system.Firstly,analyze the performance of the system,use the system input parameters as the design parameters of the compression device,and control the temperature of the combustion chamber as a fixed value.Secondly,establish a calculation model for the power system under stable operating conditions by calculating the relationship between flow rate and combustion chamber temperature.Thirdly,during the start-up process of the unit,the preheated steam is made to enters the MSR device for reheating to effectively separate the moisture carried by the saturated steam.Then,set and adjust the difference between the reheater tube plate temperature and the extraction temperature,use optical fiber communication to transmitted the data from the PLC to the central control equipment,and the set frequency is input through PID to control the Booster pump.Finally,after the bypass valve supplies water,when the water pressure is low,the control operation of the unit is completed by starting the booster pump to raise the water pressure.The experimental results show that when the temperature reaches 150 C,the low-temperature steam pressurization of the experimental group can reach 0.4 MPa,effectively increasing the steam pressure difference and improving the control adaptability of the pressurization system.