Detailed explanation of screw compressor structure and working principle
Screw compressors, also called screw compressors, include screw air compressors and screw process compressors (vinyl chloride compressors, etc.). Screw compressors are positive displacement twin-screw oil-injected compressors, generally box-type skid-mounted structures. What I want to share with you today is the structure and working principle of screw compressors. Let’s take a look!
Detailed explanation of screw compressor structure and working principle-picture
One, the working principle of screw compressor
1. Inhalation process:
The suction port on the intake side of the screw type must be designed so that the compression chamber can fully inhale, while the screw type air compressor has no intake and exhaust valve groups. The intake only depends on the opening and closing of a regulating valve. When the rotor rotates, the tooth groove space of the main and auxiliary rotors has the largest space when it turns to the opening of the inlet end wall. At this time, the tooth groove space of the rotor communicates with the free air of the inlet, because the tooth groove space is The air is completely exhausted. When the exhaust is completed, the tooth groove is in a vacuum state. When it is turned to the air inlet, the outside air is sucked in and flows into the tooth groove of the main and auxiliary rotors along the axial direction. Screw air compressor maintenance reminds that when the air fills the entire tooth groove, the air inlet side end of the rotor turns away from the air inlet of the casing, and the air between the tooth grooves is closed.
2. The process of sealing and conveying:
At the end of the suction of the main and auxiliary rotors, the peaks of the main and auxiliary rotors are sealed with the casing. At this time, the air is closed in the grooves and no longer flows out, that is, [closed process]. The two rotors continue to rotate, and their tooth peaks and grooves coincide at the suction end, and the anastomotic surface gradually moves to the exhaust end.
3. Compression and injection process:
During the conveying process, the meshing surface gradually moves to the exhaust end, that is, the tooth groove between the meshing surface and the exhaust port gradually decreases, the gas in the tooth groove is gradually compressed, and the pressure increases, which is the [compression process]. At the same time of compression, the lubricating oil is injected into the compression chamber to mix with the chamber air due to the pressure difference.
4. Exhaust process:
When the meshing end surface of the rotor of the screw air compressor is turned to communicate with the exhaust of the casing, (the pressure of the compressed gas is the highest at this time) the compressed gas starts to be discharged until the meshing surface of the tooth peak and the tooth groove moves to the exhaust At this time, the tooth groove space between the meshing surface of the two rotors and the exhaust port of the casing is zero, and the (exhaust process) is completed. At the same time, the length of the tooth groove between the meshing surface of the rotor and the intake port of the casing reaches the maximum Long, the inhalation process is going on again.
2. Features of screw compressor
As a kind of rotary refrigeration compressor, screw refrigeration compressor has the characteristics of both piston type and power type (speed type).
1) Compared with reciprocating piston refrigeration compressors, screw refrigeration compressors have a series of advantages such as high speed, light weight, small size, small footprint, and low exhaust pulsation.
2) The screw refrigeration compressor has no reciprocating mass inertia force, good dynamic balance performance, stable operation, small vibration of the base, and a small foundation.
3) The screw-type refrigeration compressor has a simple structure, a small number of parts, no wearing parts such as air valves, piston rings, etc. Its main friction parts such as rotors, bearings, etc., have relatively high strength and wear resistance, and are lubricated The conditions are good, so the machining volume is small, the material consumption is low, the operation cycle is long, the use is relatively reliable, and the maintenance is simple, which is beneficial to realize the automation of operation.
4) Compared with speed compressors, screw compressors have the characteristics of forced air delivery, that is, the displacement is almost not affected by the discharge pressure, and no surge phenomenon occurs when the displacement is small. Within the scope of working conditions, high efficiency can still be maintained.
5) The use of sliding valve adjustment can realize stepless energy adjustment.
6) Screw compressors are not sensitive to liquid intake and can be cooled by oil injection. Therefore, under the same pressure ratio, the exhaust temperature is much lower than that of the piston type, so the single-stage pressure ratio is higher.
7) There is no clearance volume, so the volumetric efficiency is high.
