Efficient compaction with a system: The functional principle of the screw compactor
Screw compressors are positive displacement machines that combine the advantages of reciprocating and turbomachinery. Their reliability and almost wear-free operation have led to their application in almost all industrial sectors.
The two rotors are equipped with helically shaped teeth that run with very little clearance to each other and to the housing.
When the rotors turn, a spatially extending V-shaped working chamber forms on the suction side of the compressor between each pair of main and auxiliary rotor teeth. The volume of this chamber initially increases from zero to a maximum (suction process).
During this phase, the working chamber is connected to the compressor's suction port.
As the rotors continue to turn, the gas is transported further and separated from the suction chamber by the rotor teeth.
The gas volume located between the rotors, which are tightly enclosed by the housing, is continuously reduced on the discharge side of the compressor until the outlet contour integrated into the housing is reached, which releases the connection to the discharge port (compression process). The position of this contour and the size of the outlet opening determine the pressure ratio and the level of the achievable final pressure.
Subsequently, the gas volume is completely discharged against the final pressure prevailing on the discharge side.
This process repeats several times with each main rotor revolution, so that, in contrast to compression with piston compressors, practically continuous, low-pulsation compression takes place, and this without any dead space.
Air and Gas Compression
- Flow volume from 50 to 10,000 m³/h
- Pressures from 0 to 80 bar
- Single-stage
- Larger flow volumes and higher pressures on request
Control Options for VPT Screw Compressors
VPT offers volume control from 0 to 100% flow rate at constant final pressure.
Speed Control
Speed control via frequency converter processes a 4…20mA signal and continuously regulates the main drive motor speed and thus the flow rate at constant final pressure.
Control range: 40 – 100%
Slide Valve Control
In this type of control, which is only used in oil-injected machines, the measuring signal from the pressure sensor controls a servo valve. By hydraulic actuation of the control slide valve located under the rotors, the volume of the working chamber is reduced or increased. This continuously regulates the compressor's delivery capacity.
Control range: 20-100%
Bypass Control
Bypass control should only be used under constant operating conditions, as the compressor's power consumption always remains constant during controlled operation.
If the minimum permissible control range for speed or slide valve control is exceeded, the excess gas quantity can be returned to the suction side via a bypass controller.
This achieves a control range of the compressor system from 0 to 100%.
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