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How dose the twostage screw compressor working?

Screw air compressor is a volumetric compressor, which achieves the purpose of gas compression by gradually reducing the working volume.

The working volume of screw air compressor is composed of a pair of slots of rotors placed parallel to each other and meshing with each other and a pair of housing containing the rotors. When the machine is running, the teeth of the two rotors are inserted into each other's alveolus, and as the rotors rotate, the teeth of the opposite alveolus move towards the exhaust end, the volume closed by the opposite teeth is gradually reduced, and the pressure is gradually increased. When the required pressure is reached, the alveolus is connected with the exhaust port and the exhaust is realized.

twostage_screw_compressor_principle

After a slot is inserted by the meshing opposite teeth, two spaces are formed. The slot near the suction end is the suction volume, and the volume close to the exhaust end is the volume of compressed gas. With the operation of the compressor, the teeth of the opposite rotor inserted into the slot move towards the exhaust end, which enlarges the suction volume and reduces the volume of compressed gas, thus realizing the suction and compression process in each slot. When the pressure of compressed gas in the slot reaches the required exhaust pressure, the slot communicates with the exhaust orifice and starts the exhaust process. The change of the suction volume and the compression volume divided by the teeth of the opposite rotor is recurring, so that the compressor can continuously suck, compress and exhaust.

 

Screw Compressor working principle:

1. Inhalation process:

The screw-type intake side suction port must be designed so that the compression chamber can suck in sufficiently, while the screw-type air compressor has no intake and exhaust valves. The intake is regulated only by opening and closing of a control valve. When the rotor rotates, the space z* of the tooth groove of the main and auxiliary rotors is large when the rotor rotates to the opening of the intake end wall. At this time, the space of the tooth groove of the rotor communicates with the free air of the intake port. At the end of exhaust, the groove is in a vacuum state. When the groove is turned to the intake port, the outside air is absorbed and flows into the groove of the main and auxiliary rotors along the axis. Maintenance of screw air compressor reminds that when air fills the whole dental groove, the end face of the intake side of the rotor turns away from the intake port of the casing, and the air between the dental grooves is closed.

2. Closing and conveying process:

At the end of the suction, the main and auxiliary rotor teeth summit and the casing are sealed. At this time, the air is no longer outflow in the gear groove, i.e. [closing process]. As the two rotors continue to rotate, their tooth peaks coincide with the tooth grooves at the suction end, and the coincidence surface moves towards the exhaust end gradually.

twostage_screw_compressor_principle

3Compression and injection process:

In the process of conveying, the meshing surface moves to the exhaust end gradually, that is, the groove between the meshing surface and the exhaust port decreases gradually, the gas in the groove is compressed gradually, and the pressure is increased, that is, the compression process. At the same time, the lubricant is injected into the compression chamber to mix with the chamber gas due to the effect of pressure difference.

4. Exhaust process:

When the meshing face of the rotor in the maintenance of screw air compressor turns to be connected with the exhaust of the casing, the compressed gas starts to be discharged until the meshing face of the tooth peak and the tooth groove moves to the exhaust face. At this time, the space of the tooth groove between the meshing face of the two rotors and the exhaust port of the casing is zero, that is to say, the exhaust process is completed. At the same time, the meshing face of the rotor and the inlet of the casing are discharged. The length of the teeth groove between them is z* long, and the suction process is going on again.