Operation principle of screw air compressor
Compressed air is generated from an air compressor where the mechanical energy of the electric motor or of the internal combustion engine is converted into compressed air and thermal energy. Screw air compressors are operated according to the following two principles:
– Principle of changing volume: The air is directed into the storage chamber, where the volume of the chamber will be smaller. Thus according to Boyle-Mariotte’s law, the pressure in the storage chamber will increase. Air compressor operates according to this such principle as screw air compressor, piston compressor, gear, vane
– Kinetic principle: The air is driven in the containment chamber and accelerated by a high-speed rotating part, where the compressed air pressure is generated by the speed difference, which produces very high flow and power. Air compressors operate according to this principle as centrifugal compressors.
Currently on the market there are 2 types of screw air compressors: Double screw air compressors produced by many manufacturers: Hitachi, Kobelco, SCR, Atlas, Garner denver and the most modern Z screw compressors today are assembled and manufactured by Mitsui Seiki – Japan, TU-SEIKI is assembled and manufactured by Vietnam.
The difference between conventional screw air compressor with – double axis and air compressor with Z axis – Japanese new technology.
1 / Double screw air compressor with two axises. Main axis and auxiliary axis.
The type of twin screw air compressor was around 1950 and occupied a large market in compressed air, this type of air compressor has a special cover around two rotating screws, one convex and one concave. The teeth of the two screws fit together and the number of less convex screw teeth is less than 1 to 2 tooth. The two screws must rotate synchronously with each other, between the screws and the covers with very small openings.
When the screw rotates rapidly, the air is sucked into the shell through the inlet and into the air chamber between the screws and there is compressed air between the tooth when the air chamber is smaller, then the compressed air releases to the exit door. Both the inlet and outlet doors will be opened automatically when the screw rotates or does not cover the doors. At the exit of the air compressor, there is a one-way valve fitted to prevent the screws from rotating when the compression process cease.
2 / Z-shaped screw air compressor
– Consist of 1 main screw (made of metal) and 2 blades that are symmetrically matched through the main screw. 2 vanes are enclosed by a metal plate and 1 blade plate (made of a carbon-containing compound made of metal)
– The vanes are coupled with 1 metal plate and 1 blade plate (the blade plate is bigger than the metal plate enclosed with the main screw.)
– The purpose of such a coupling is to avoid corrosion of the main screw. (To the maintenance period only replace blade plate).
– Due to the structure and screw Z material of the designed head, the radial and axial loads allow for mutual suppression (according to the theory of load is almost zero). So Z screw head is stable, runs smoothly, high performance and very durable.
3 / The outstanding advantages of air compressor TU Seiki compared to the twin shaft air compressor
Because Z screw head compression structure is specially designed, the air compressor Mitsuiseiki rotation speed is much smaller than the twin screw line => Heat generation while the machine operates lower => stable, smooth running and very durable.
The number of compressed air trenches is 3 times more than double screw so the amount of compressed air is more.
The temperature when the machine runs stably fluctuates from 800C to 900C
Using only one compression level, the pressure was achieved from 8.5 to 9 bar.
Direct coupling drive does not cause energy loss.
Ultra-long screw life due to reduced load on the drive (smaller rotation speed so life will be greater).