Energy-Saving Technology for Screw Air Compressors

Screw air compressors have become core equipment in industrial production for compressed air and process gas conveyance, thanks to their compact structure, stable operation, high reliability, and ease of use. They are widely used in key sectors such as petrochemicals, metallurgy and mining, and new energy power generation. According to statistics, the energy consumption of screw air compressors can account for 15-25% of the total energy consumption in industrial enterprises, and in some high-energy-consuming industries, it can even exceed 30%. Moreover, most traditional screw air compressors suffer from low operational efficiency and severe energy waste.

Under the guidance of the “carbon peak and carbon neutrality” strategy, industrial energy conservation and emission reduction have become an important path for enterprises to reduce costs and improve efficiency. The energy-saving renovation of screw air compressors is urgent. With advancements in mechanical manufacturing and automation control, a series of new energy-saving technologies have been widely applied to screw air compressors, effectively reducing energy consumption.

In response to the sources of energy loss, the industry has developed mature energy-saving technologies, which reduce energy consumption through methods such as reducing leaks, lowering friction, and optimising matching. The following section highlights key technologies and their applications.

• Variable-Frequency Speed Regulation Energy-Saving Technology: By changing the frequency of the motor’s power supply, the rotor’s speed is adjusted to match the exhaust volume with the demand for compressed air.
• Gap Optimisation and Precision Machining Technology: By optimising the gap design and enhancing machining accuracy, leakage losses are reduced.
• High-Efficiency Cooling System Energy-Saving Technology: By optimising the structure, upgrading the medium, and implementing intelligent control, the cooling effect is improved.
• Lubrication System Upgrade Energy-Saving Technology: By using synthetic lubricating oil, friction is reduced and sealing gaps are minimised.
• System Integration Optimisation Energy-Saving Technology: Through overall design, matching losses are reduced, achieving energy savings across the entire system.

Three case studies from different industries are presented to verify the actual effectiveness of energy-saving technologies and provide references for enterprises.

• Chemical Plant: Variable-Frequency Speed Regulation and System Integration Optimisation: A chemical plant in Yangzhou replaced four 37kW fixed-speed air compressors with units that have variable-frequency speed regulation and system integration optimisation. The plant’s air demand fluctuates between 30% and 75%, leading to frequent loading and unloading of the compressors and significant energy waste. After the renovation, the system pressure became stable, and the average energy consumption was reduced by 26%, resulting in an annual electricity savings of 340,000 kWh.
• Mining Company: Gap Optimisation and Lubrication System Upgrade: A mining company upgraded two 55kW old air compressors. Due to wear and tear of components and excessive gaps, the compressors had high energy consumption. After the upgrade, leakage and friction losses were reduced by 28% and 22%, respectively, and the overall machine efficiency improved by 9%. The two compressors saved 144,000 kWh of energy annually.
• Food Processing Plant: High-Efficiency Cooling and System Management Optimisation: A food processing plant upgraded three 22kW air compressors. During the summer, the cooling system was insufficient, leading to high energy consumption and maintenance costs. After the upgrade, the cooling system’s energy consumption was reduced by 32%, and lubricating oil consumption was reduced by 35%. The three compressors saved 144,000 kWh of electricity annually.