Automatic control valves (automatic control valves) play a vital role in the chemical industry. They ensure the stability, safety and efficiency of the production process by automatically adjusting the flow, pressure, temperature and other parameters of fluids (gas, liquid, slurry, etc.). The following are its specific applications and key points:

1. Main application scenarios
(1) Process control
● Flow regulation: The flow of the medium in the pipeline is accurately controlled by regulating valves (such as pneumatic/electric regulating valves) to meet the process requirements of equipment such as reactors and distillation towers.

● Pressure control: Pressure reducing valves and back pressure valves are used to maintain system pressure stability to prevent overpressure or vacuum (for example, in high-pressure reactors or steam pipe networks).

● Temperature control: Linked with the heat exchange system, the temperature is automatically managed by adjusting the flow of steam or cooling medium.

(2) Safety protection
● Emergency shut-off: The solenoid valve or quick shut-off valve in the safety interlock system (SIS) can be instantly closed in the event of leakage, fire or abnormal pressure to prevent the accident from expanding (such as ESD emergency shutdown system).

● Pressure relief protection: The safety valve (PSV) or bursting disc automatically releases the medium when overpressure occurs to protect the equipment.

(3) Material distribution and mixing
● Multi-way switching: Three-way valves or multi-way valves are used to switch between different process paths (such as alternating feeding of reaction stations).

● Proportional mixing: Control the ratio of multiple raw materials (such as acid-base neutralization, polymerization reaction).

(4) Special process requirements
● Corrosive media: Use fluorine-lined valves, ceramic valves and other corrosion-resistant materials (such as handling sulfuric acid and chlorine-alkali).

● High viscosity/granular media: Use ball valves, plug valves or diaphragm valves (such as slurry transportation).

● Aseptic environment: Sanitary valves are used for pharmaceutical or food-grade chemical production.

2. Special requirements of the chemical industry
(1) Explosion-proof certification: In flammable and explosive environments (such as petrochemicals), it must comply with ATEX or IECEx standards.

(2) Sealing: The valve seat leakage level must reach ANSI Class IV or above to prevent leakage of toxic media.

(3) Material compatibility: The valve body and sealing materials must be resistant to media corrosion (such as Hastelloy and PTFE lining).

(4) Intelligence: Integrated intelligent positioner, support for HART/FF communication protocol, and linkage with DCS/PLC system.

3. Advantages and Challenges
(1) Advantages:

● Improve production efficiency and reduce manual intervention.

● Precise control improves product quality consistency.

● Reduce the risk of safety accidents.

(2) Challenges:

● Complex working conditions (high temperature, high pressure, corrosion) require high valve durability.

● Maintenance requires professional technicians, especially when toxic media are involved.

4. Typical cases
(1) Ethylene cracking unit: The regulating valve controls the feed flow of the cracking furnace, and the safety valve protects the high-pressure pipeline.

(2) Polymerization reactor: The ratio of monomer to catalyst is accurately controlled by the proportional valve.

(3) Wastewater treatment: pH regulating valve automatically adds acid and alkali to neutralize wastewater.

Automatic valves are an indispensable part of chemical automation. Their selection, installation and maintenance must be closely integrated with process requirements and safety standards.