Process and control requirements

Process and control requirements

1. Feeding control

① Check if the liquid level SQ2, furnace temperature ST, and furnace pressure SP are all below the given values (set values are all logical quantities).

② If it is less than the given value, open the exhaust valve YVl and the feed valve YV2.

③ When the liquid level rises to the upper liquid level SQl, the exhaust valve YVl and the feed valve YV2 should be closed.

④ Delay for 20 seconds, open nitrogen valve YV3, nitrogen enters the reaction furnace, and the pressure inside the furnace rises.

⑤ When the pressure rises to the given value, i.e. SP="1", close the nitrogen valve.

2. Heating reaction control

① The AC contactor KM is energized, connect the power supply to the heating furnace heater EH.

② When the temperature rises to the given value (ST: "1"), the heater power is cut off, and the AC contactor KM loses power

③ The heating process ends with a 10 minute delay.

3. Release control

① Open the exhaust valve to lower the pressure inside the furnace to the predetermined minimum value (SP: "0").

② Open the vent valve, and when the solution in the furnace drops to the lower liquid level (SQ2="0"), close the vent valve and exhaust valve. The system has been restored to its original state and is ready to enter the next cycle.

2. Working principle of heating reaction furnace

The basic composition of the temperature control system for the heating reaction furnace is shown in the following figure. It consists of four parts: PLC main control system, solid-state relay, heating furnace, temperature sensor, etc.

The implementation process of temperature control for the heating furnace is as follows: first, the temperature sensor converts the temperature of the heating furnace into a voltage signal. The A/D inside the PLC main control system converts the voltage signal sent in into a digital quantity that the PLC can recognize. Then, the PLC compares the temperature value given by the system with the feedback temperature value and processes it through PID operation, Provide a control signal to the input terminal of the solid-state relay to control whether the output terminal of the solid-state relay is conductive, so as to start or stop heating in the heating furnace.

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