Applications of Screw Compressors

Screw compressors are positive displacement compressors that use two intermeshing screw rotors to compress gas. They are widely used in various fields due to their high efficiency, smooth operation, compact structure, and ability to adapt to a wide range of operating conditions. Their applications can be categorised by industry or function as follows:

1. General industrial compressed air applications

Compressed air serves as the ‘second power source’ in industry, and screw compressors are the core equipment for medium to large-scale industrial air supply systems. They are primarily used for:

Manufacturing: Powering pneumatic tools (such as wrenches and pneumatic drills), cylinders/valves in automated production lines, and air supply for coating equipment, among others, across industries including automotive manufacturing, mechanical processing, and electronics assembly.

Mining and infrastructure: Providing high-pressure air sources for tunnel drilling machines, mining air drills, etc., suitable for harsh environments such as outdoor and dusty conditions (requires a filtration system).

Textiles and Paper: Used for pneumatic control in fabric shaping and vacuum suction in paper conveying, requiring oil-free screw compressors to avoid contaminating materials.

2. Refrigeration and Air Conditioning Applications

Screw compressors are the mainstream core components of medium to large-scale refrigeration/air conditioning systems, particularly suited for applications with medium to high refrigeration capacity requirements:

Large central air conditioning systems: chiller units in buildings such as shopping malls, office buildings, and hotels, which achieve heat exchange by compressing refrigerants (e.g., R134a, R22), with single-unit cooling capacity reaching thousands of kW.

- Industrial refrigeration: Food cold storage, chemical reactor cooling, plastic mould cooling, etc., can be combined with a secondary coolant (e.g., ethylene glycol) to achieve low-temperature control (-20°C to 10°C).

- Heat pump systems: Used for industrial heating, district heating, or hot water supply (e.g., hotels, hospitals), medium-to-high-temperature screw heat pumps can achieve outlet water temperatures of 60°C to 80°C with high coefficient of performance (COP).

3. Petrochemical and Energy Sector

For process gas compression or energy recovery, screw compressors offer significant advantages in terms of dirt tolerance and adaptability to varying operating conditions:

Oil and Gas Extraction and Transportation: Compressed natural gas (CNG) for pipeline transportation, or injection of high-pressure gases (e.g., CO₂) into oil wells to enhance crude oil recovery; in shale gas extraction, compression of associated gas for recovery.

Process gas treatment: Compressing liquefied petroleum gases (LPG) such as propane and butane, or handling inert gases (e.g., nitrogen) in chemical reactions requires oil-free screw compressors to prevent gas contamination.

-New Energy Sector: Compressed biomass gas (straw/landfill gas) is used for power generation, or in the hydrogen energy supply chain, compressed hydrogen gas (requiring ultra-high-pressure oil-free models) is used for storage and transportation.

4. Food and pharmaceutical industry

Compressed air quality requirements are extremely high (oil-free, sterile), and oil-free screw compressors (such as dry screw or water-lubricated screw compressors) are core equipment:

Food processing: pneumatic control for bread proofing, sterile gas sources for beverage filling, and gas compression for vacuum packaging (e.g., CO₂ preservation).

Pharmaceutical production: clean gas sources for pharmaceutical production facilities (to drive sterile valves), refrigeration compression for freeze-drying equipment (low-temperature control of drug crystallisation), which must comply with GMP certification requirements.

5. Transportation and maritime sector

Adapting to the ‘compact, vibration-resistant’ requirements of mobile equipment:

Rail transport: Air conditioning systems for high-speed rail and metro trains, using screw compressors to compress refrigerants for cabin temperature control.

Marine engineering: Central air conditioning for large cargo ships, refrigeration for cold storage compartments (transporting fresh produce), or auxiliary air sources for power systems (e.g., pneumatic motors for engine startup).

Summary

The core application of screw compressors is to meet the demand for gas compression with medium to high flow rates and a wide pressure range (0.3–4.0 MPa), and to differentiate designs such as ‘oil-injected/oil-free’ and ‘single-stage/two-stage’ to adapt to specific scenarios—oil-injected models focus on industrial general-purpose applications (low cost, high efficiency), while oil-free models dominate clean-room applications in food, pharmaceuticals, and chemicals.