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 the semi-automati