The Application of E7-200 Smart PLC in the Heating System of High rise Buildings

Introduction to the functions of the heat exchange station:

The urban centralized heating system is relatively popular in the northern regions of China. Thermal power plants transport hot water to various heat exchange stations through the urban pipeline network, and then transmit the hot water to residential areas, office buildings, and other places through heat exchange units and pumps.

The working principle of a heat exchange station is: the primary network heat source is sent to the heat exchange station through a pipeline and enters the heat exchanger. Through the heat exchange of the heat exchanger, the primary network heat source is exchanged into the secondary network heating pipeline, and the secondary network heating pipeline is led out to the heat user. The return water from the secondary network is cleaned by a filter and then circulates into the heat exchanger. It is heated by steam or high-temperature water for heating. After entering the heat exchanger, the steam or high-temperature water becomes condensed water or high-temperature return water, which returns to the heat source for circulation in the primary and secondary network heating systems. The make-up pump injects soft water into the system to maintain a constant system pressure.

Primary network: refers to the pipeline network connected between the initial heat exchange station (or large regional boiler room) of a thermal power plant and the heat exchange station.

Secondary network: refers to the pipe network connected between the heat exchange station and the heat users.

Project Introduction:

  This heat exchange station provides heating for a high-rise residential area, divided into two systems based on floor height: high zone and low zone. The high and low areas share a direct supply pipeline network, and the water supply of the high area system is powered by a dedicated booster circulating pump, which is supplied to the high area through the main water supply pipe. Each system includes: plate heat exchanger, electric control valve, circulating water pump, make-up water pump, primary water secondary pump and its auxiliary equipment; It can ensure winter heating for surrounding residential areas and commercial streets.

Plate heat exchange unit

Process screen

PLC control system configuration

The main control system of this project adopts the Huceen E7-200SMART PLC, which uses the Ethernet port provided by the CPU body to communicate with the touch screen. The temperature of the water pipe is collected through an extended thermal resistance simulation block. The extended analog input module is used to collect the temperature and pressure of the water pipe, as well as the current and frequency of the frequency converter. The extended analog output module is used to adjust the frequency of the frequency converter and the on-site valve opening.

Unit 2 PLC

Electric control cabinet

Main functions:

Water pump rotation training: Multi pump automatic cycle switching to avoid wear or corrosion caused by long-term use or shutdown of the water pump.

Interlock protection: water shortage protection, water pump fault protection, frequency converter fault alarm, enable protection to automatically stop the pump, and eliminate faults to automatically start the water pump.

Temperature compensation: The temperature can be automatically adjusted and set according to the outdoor temperature.

Automatic water replenishment: When automatic water replenishment is activated, the equipment does not require personnel to be on duty, and the pressure of the circulating pipeline is automatically constant at the target set value.