2-6 What are the differences between twin-screw air compressors and single-screw air compressors?
Single & twin-screw air compressors differ in force balance, cost, reliability, efficiency, processing equipment, & applicability. Twin-screw has higher cost, reliability, & mature processing but limited pressure. Single-screw suitable for high pressure, lower cost, but less reliable & efficient.
Case Details
Answer: (1) Force balance. The radial and axial gas forces borne by the screw of a single-screw air compressor can be automatically balanced, and the star gear teeth bear the gas force, which requires the star gear teeth to have sufficient strength and rigidity; The screw rotor of a twin-screw air compressor bears large radial and axial gas forces, which requires the screw to have sufficient strength and rigidity.
(2) Manufacturing cost. The screw and star gear bearings of a single-screw air compressor can use ordinary bearings, which has a lower manufacturing cost; Since the loads of the two screw rotors of a twin-screw air compressor are relatively large, it is required to use bearings with higher precision, which has a higher manufacturing cost.
(3) Reliability. The star gear of a single-screw air compressor is a vulnerable part. In addition to having high requirements for the star gear material, the star gear also needs to be replaced regularly. There are no vulnerable parts in a twin-screw air compressor, and the trouble-free operation time can reach 40,000 to 80,000 hours (regular overhauls are required in the middle).
(4) Efficiency. As the running time increases, the wear of the star wheel of the single-screw air compressor will lead to a decrease in air volume and efficiency.
(5) Noise and vibration. The noise and vibration of single-screw air compressors and twin-screw air compressors are basically the same.
(6) Processing equipment. Single-screw air compressors do not have mature dedicated processing equipment, which leads to unstable product performance. Twin-screw air compressors have mature screw-specific milling machines and grinders to ensure stable product performance.
(7) Operation and maintenance. The daily operation and maintenance of single-screw air compressors and twin-screw air compressors are basically the same.
(8) Applicability. Single-screw air compressors are suitable for high exhaust pressure occasions. Due to the limitations of rotor stiffness and bearing load, twin-screw air compressors can only be used in medium and low pressure ranges, and the exhaust pressure generally cannot exceed 4.5MPa.
The manufacturing process of twin screw is more complicated than single screw in terms of structure. In the new state, the efficiency of single screw compressor and twin screw compressor is basically the same. However, the manufacturing technology of single screw in China is not as mature as that of twin screw. The main problem is to solve the transmission and sealing. In other words, the single screw is lacking in life and maintenance.
