PID diagram of purified water distribution system

Prepare qualified purified water and enter the purified water storage tank. After being pumped to various water consumption points, it is circulated back to the storage tank. During operation, the water quality and operation mode are automatically controlled through detection elements such as liquid level, temperature, conductivity, and flow rate.

The system includes purified water storage tanks, sanitary centrifugal pumps, sanitary heat exchangers, diaphragm valves, respirators, on-site display control systems, and various instruments.

1) Purified water is prepared by preparation equipment and transported to the purified water buffer tank through a pipeline circulation system.

2) The storage and circulation temperature of purified water is at room temperature.

3) Install a circulating sanitary pump with variable frequency control in the purified water circulation system. Adjust the pump output based on the flow meter signal before returning to the tank to ensure that the pipeline flow rate meets the requirements.

4) The conductivity of purified water is detected by the online conductivity meter before returning to the tank. If the conductivity value of purified water is greater than the required value, the instrument sends a signal to the PLC, which sends an alarm signal and controls the opening of the online pneumatic diaphragm valve to discharge the unqualified water. If the conductivity value exceeds the requirement for a continuous period of time, the system will automatically shut down and issue an alarm signal to prompt the operator to conduct an inspection.

5) Install a temperature gauge and temperature sensor in the front pipeline of the heat exchanger for temperature control during pasteurization of the pipeline.

6) The purified water storage tank is equipped with a liquid level gauge and sets the maximum and minimum liquid level parameters. When the liquid level exceeds the maximum value, the inlet valve at the top of the tank closes. When the liquid level is below the minimum value, the delivery pump is turned off.

7) By installing an online flow meter before the return tank, the variable frequency pump is controlled to ensure that the flow rate of purified water in the pipeline is not lower than the minimum flow rate of 1m/s.

8) During the sterilization process, the temperature, pressure, flow rate, and conductivity inside the pipelines and tanks will be recorded by the control system.

9) The system has an electrical control system (1 set of PLC), and the control panel is directly installed in the stainless steel control cabinet on the storage and distribution system bracket, containing electrical equipment PLC＆OIT。 This control system facilitates the operation, monitoring, and control of equipment by operators. The Operator Interface Terminal (OIT) is a monitoring panel that displays the operating parameters of the device. Alarm, action, sterilization steps, process set points, and process values are all displayed on OIT.