摘  要：本项目利用西门子S7-300系列PLC完成了对原有换热系统的改造。原有换热系统通过手动设定PID表的温度设定值来达到对换热阀门开度大小的控制，改造后换热系统由半自动控制系统转换为全自动控制系统，并最大限度的利用了回收的凝结水的热量。

关键词：换热系统   西门子S7-300PLC   凝结水温度

Abstract: This project completed the renovation of the original heat exchange system by using the Siemens S7-300 series PLC. The original heat exchange system control the heat exchange valve opening degree by setting the PID table temperature manually. After the renovation, the heat exchange system from t