In the chemical industry, valves are used to control the flow, pressure, and temperature of chemical media, ensuring efficient, safe, and stable chemical production processes. Due to the diversity and complexity of chemical media, valves have stringent requirements for performance and materials. Below are specific applications and special requirements of valves in the chemical industry:
Application Scenarios
1. Chemical Reaction Units:
- Control the flow of reactants, catalysts, and reaction products.
- Require valves with high sealing, corrosion resistance, and high temperature resistance.
2. Separation and Purification Units:
- Control fluid flow during separation and purification processes such as distillation, absorption, and extraction.
- Require valves capable of precise flow and pressure regulation.
3. Transport Pipeline Systems:
- Control the transportation of chemical media between different process units.
- Require valves with abrasion resistance, corrosion resistance, and high-pressure resistance.
4. Storage and Loading/Unloading Systems:
- Control fluid flow during chemical storage and loading/unloading processes.
- Require valves with high sealing, explosion protection, and corrosion resistance.
5. Safety Protection Systems:
- Used to prevent system overpressure, leakage, and uncontrolled reactions.
- Require reliable safety valves and emergency shut-off valves.
Special Requirements
1. Corrosion Resistance:
- Many chemical media are corrosive; valves must withstand corrosion from acids, alkalis, salts, and organic solvents.
- Materials typically include stainless steel, Hastelloy alloys, titanium alloys, or fluorine-lined materials.
2. High Sealing Performance:
- Ensure no leakage under high temperature, high pressure, and corrosive media conditions to prevent environmental pollution and safety accidents.
- Use metal seals or composite sealing materials to ensure effective sealing under extreme conditions.
3. High Pressure and High Temperature Resistance:
- Many chemical reactions occur under high temperature and pressure conditions; valves must withstand these harsh conditions.
- Materials typically include high-strength alloy steel or special high-temperature resistant materials.
4. Explosion-proof Design:
- Due to the presence of flammable and explosive media in chemical production, valves must have explosion-proof designs to ensure safety in hazardous environments.
- Certification such as ATEX is required for explosion-proof compliance.
5. Abrasion Resistance:
- Valves handling media with solid particles must have abrasion-resistant properties.
- Use wear-resistant materials such as hard alloys or ceramic coatings.
Typical Valve Types
1. Ball Valves:
- Suitable for rapid opening/closing and tight shut-off applications.
- Full-bore design reduces fluid resistance, superior sealing performance suitable for transport pipeline systems and storage units.
2. Gate Valves:
- Suitable for fluid isolation and frequent switching applications.
- Robust structure, high-pressure and high-temperature resistance, suitable for chemical reaction units and transport pipeline systems.
3. Butterfly Valves:
- Suitable for large-diameter pipeline flow control.
- Simple structure, lightweight, quick opening/closing, suitable for separation and purification units and air conditioning systems.
4. Globe Valves:
- Suitable for applications requiring precise flow and pressure regulation.
- Simple structure, excellent regulation performance, good sealing performance, suitable for chemical reaction units and separation units.
5. Check Valves:
- Prevent reverse flow, protect equipment safety.
- Suitable for various process pipeline systems.
6. Safety Valves:
- Prevent system overpressure, protect equipment and personnel safety.
- Suitable for high-pressure vessels and pipeline systems.
7. Emergency Shut-off Valves:
- Used for quickly cutting off fluid flow in emergencies, preventing accidents from spreading.
- Suitable for storage and loading/unloading systems and chemical reaction units.
Maintenance and Operation Considerations
1. Regular Inspection and Maintenance:
- Regularly inspect valve sealing and operational performance, promptly replace worn or damaged parts.
- Clean valves internally and externally to prevent fouling and corrosion.
2. Lubrication:
- Regularly apply appropriate lubricants to valves requiring lubrication to ensure flexible operation.
- Use lubricants suitable for high temperature and high pressure to prevent lubricant failure.
3. Fastening Component Inspection:
- Regularly inspect fastening components of valve connections to ensure tightness and prevent leaks.
4. Operating Procedures:
- Operators must strictly follow operating procedures for valves to avoid excessive force or rapid operation.
- Provide operational training to ensure operators understand valve performance and operating methods.
5. Emergency Handling:
- Develop and familiarize personnel with emergency response plans to promptly respond to emergencies such as valve leaks or failures.
Typical Cases
1. Ball Valves for Chemical Reaction Units:
- Ball valves used in chemical reaction units require high sealing and corrosion resistance; valve bodies and balls are typically made of Hastelloy alloys or titanium alloys.
2. Butterfly Valves for Separation Units:
- Butterfly valves used in separation units require high sealing and high temperature resistance; valve bodies and discs are made of high-temperature resistant materials.
3. Gate Valves for Transport Pipeline Systems:
- Gate valves in transport pipeline systems require high-pressure and abrasion resistance; valve bodies and gates are made of high-strength alloy steel or hard alloy materials.
4. Emergency Shut-off Valves for Storage Systems:
- Emergency shut-off valves in storage systems require high sealing and explosion-proof performance; valve bodies and seats are made of explosion-proof materials.
5. Safety Valves for Safety Protection Systems:
- Safety valves in safety protection systems require high reliability and rapid response capabilities; suitable for high-pressure vessels and pipeline systems.
By selecting appropriate valve types and materials and conducting regular maintenance and inspection, valves in the chemical industry can operate stably under various harsh environments, improving production efficiency and equipment safety.