Types of Air Compressors.
A rotary screw air compressor or Screw Air Compressors are a type of air compressors that compress air for pneumatic control machines. It uses two rotors to create the pressure needed for air compression. They are one of the easiest types of air compressors to supply smooth compressed air. The other type of positive displacement compressor is the reciprocating or piston type compressor.
Equivalent to positive displacement compressors are dynamic compressors, like centrifugal compressors. These machines use radial blades to force air out.
How Screw Air Compressors are working
A screw compressor works with combination of male and female rotor that spins in the opposite direction. This movement pulls in air that is compressed as the space between the rotors and their housing decreases. The compressed air is then discharged to the air storage tank.
Both screw elements have a fixed, built-in pressure ratio dependent on the length and pitch of the screw, and discharge port also matters in pressurized air flow. Better efficiency of a screw compressor can be achieved by internal pressure with respect to working pressure. Mechanical damage losses due to high speed and compressed air losses due to very low speed can be reduced by optimization of the speed of the screws.
Type of Screw Air Compressors
There are two types of rotary screw air compressors:
- Oil-free or dry screw compressors (No Lubricant involve)
- Oil-Injected screw compressors (Contain Lubricant)
Oil-Injected screw compressor technology, the male rotor drives which is connected to the main motor via gear mechanism is responsible to drive the female rotor.
In oil-free compressor technology, a timing gear drives both rotors for harmonic running, with minimum calculated clearance between both elements.
Fix Speed and Variable Speed Screw Air Compressors
- Fixed-speed compressors run at a continuous fixed speed
- Variable speed drive (VSD) technology turns the motor at the appropriate speed in relation to the amount of air that is required
Fixed speed compressors are very efficient when continuously operating at full capacity; Most of the cases on factories do not need that amount of productivity. Before the motor comes to a complete stop, it will continue to run while no air is being produced, consequently wasting energy and money.
- Such inefficiency and waste is generally found at facilities operating multiple shifts and experiencing flow demand fluctuation throughout the day.
Modern VSD compressors increase the speed of the motor as per demand of the air, which means supplying more air flow/CFM. If the demand decreases, the motor will automatically slow down and only use the required energy to provide appropriate flow.
On slow production days, breaks in workflow, or throughout second and third skeleton shifts, VSD technology is especially helpful. This type of air compressor saves electricity and money, compared to fixed-speed models.
According Since compressed air energy usage accounts for over 80% of an air compressor’s costs, it’s important to choose efficient equipment.
Screw Compressor: A solution for all applications.
Screw air compressors are quite popular due to their flexibility. A screw air compressors is available every application. There are mainly three drive types of screw air compressors. Each type has its own benefits.
- Belt Drive: These compressors are very robust as well as easy to install and maintain. In addition, they have the lowest initial investment cost among rotary screw compressors. This combination makes them a great choice for smaller operations.
- Gear Drive: A gear drive makes compressors quieter. The investment is higher than a belt drive but also more energy efficient. Therefore, if you use the compressor a lot, this investment will pay off over time thanks to energy savings.
- Direct Drive: This is the optimum of rotary compressor technology. The innovative direct drive offers unmatched efficiency and performance. Among the three, they create the least noise. Direct drive rotary screw compressors come in different types – from a basic design for the smaller models to those with ultra-efficient variable speed drives.
Screw compressors for heavy-duty applications
If you’re running heavy-duty applications that continue over long periods of time, like in a factory, industrial plant or workshop, then you should consider upgrading to a rotary screw air compressor.
Benefits of a screw compressor in industry:
- They are designed to work 24/7
- They can operate at higher flow capacities while dissipating the heat generated
- They are relatively less noisy than piston compressors
- They receive less wear and tear
- They tend to require less space
- They discharge less oil and contaminants with the compressed air
