Share everyone’s achievements in technological upgrades in the field of automatic control

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1. Condition before technical renovation: The dampers of the exhaust fans and blowers in the centrifugal drying unit of the polymerization plant posed safety risks. The basic situation was as follows: Two dampers used double-acting cylinders as actuators, with valve positioners receiving 4–20mA analog signals to control the opening degree of the dampers. As these systems had been in operation for 5 years, some of the transmission mechanisms had worn out; furthermore, the cylinders did not have sufficient pushing force. There were no manual valves available on site, which meant that the opening degree of the dampers could not meet the required levels. As a result, the air pressure in the centrifugal drying unit failed to meet the process specifications, leading to a decrease in the quality rate of the resin products. For existing safety hazards, reasonable solutions must be developed for technical upgrades in order to improve product quality and ensure safe production. 2. Technical requirements 1. Total torque range: 1600–2000 N·m ； 2. Shaft specification: 2cm×2cm ； 3. Pneumatic double-acting cylinder actuator ； 4. Positioner with valve position feedback: input of 4~20mA DC, output of 4~20mA DC; 3. Status after technical modification: 1. Automatic control has been achieved, with the analog signals (4~20mA) from the DCS system used to control the opening degree of the dampers, and operations can be performed via the computer in the control room ； 2. It can be manually controlled on-site; the damper is equipped with a handwheel, which allows for controlling the opening degree of the damper in case automatic control fails ； 3. The opening degree of the on-site dampers can be displayed on the DCS control station, enabling operators to monitor it in real time.