Screw compressor for demanding processes

Reliable compressed air production is essential in industry, power plants, and many other sectors. AERZEN screw compressors have proven themselves worldwide in a wide range of applications and industries. They operate reliably in a wide variety of temperature ranges, both indoors and outdoors. Whether it’s air, neutral gases, or specialty gases: Thanks to their high versatility, they are suitable for demanding conveying, compression, and vacuum applications across a broad spectrum of industrial uses.

The oil-free and oil-injected screw compressors reliably convey and compress in numerous applications, such as pneumatic conveying, chemical and process engineering, and compressed air technology. Typical applications also include the aeration of sewage treatment tanks, keeping lakes and harbor facilities ice-free, supplying oxidation air to power plants, and use as jet starters for aircraft turbines.

Screw compressors are twin-shaft rotary piston machines. They operate on the displacement principle with internal compression and are known as positive-displacement compressors. This applies to all screw compressors. Their operation is based on two intermeshing rotors that continuously draw in the medium, compress it, and deliver it to the discharge port.

What sets AERZEN apart is that we have elevated reliability, ease of maintenance, user-friendliness, flexibility, and energy efficiency to a universal principle. The result is a series of unique design features. One example of this is the efficiency coefficients of the AERZEN 3+4 VML and 4+6 VM profiles. Compared to standard compressors, they save a considerable amount of energy. And what is actually the ultimate in compressor technology? The ultimate is the new E-compressors from AERZEN. With an efficiency increase of up to 6%, they unlock even more valuable potential.

How a screw compressor works:

• Displacement principle with internal compression
• Designed as a positive-displacement compressor
• Twin-shaft rotary piston machines
• Two intermeshing, helical rotors
• Continuous compression of the fluid

There are single- and double-rotor rotary compressors, but when people talk about screw compressors, they usually mean two rotors arranged in parallel with different screw profiles. These meshe together like gears and compress the gas located between the profiles through displacement. Unless the machines are oil-free, oil is injected for cooling and sealing. This process, known as liquid cooling, is particularly necessary when there are high pressure differentials between the suction and discharge sides. Oil can also help minimize wear and reduce temperatures. Top-of-the-line oil-free designs do not require this measure and feature low friction thanks to high-precision manufacturing processes and synchronized gears. It is guaranteed that no lubricant enters the chamber at any time—which qualifies the new models as completely oil-free compressors. This is particularly advantageous in applications with high requirements for purity and process reliability, such as in the food and pharmaceutical industries, as well as in chemical and process engineering.

Economic considerations are prompting many companies to switch to screw compressors. A key reason for this is their high compression efficiency, which has a positive impact on energy consumption. This is a decisive factor, especially in times of high energy prices. Heat recovery is also becoming increasingly important in this context.

Due to their basic design, screw compressors are clearly superior to reciprocating compressors in terms of efficiency. This enables a noticeable reduction in energy costs and CO2 emissions during operation. While piston compressors lose about one-tenth of the intake air through the piston rings, the pressure loss in screw compressors is significantly lower and rarely exceeds 0.1 to 0.2 percent.

The energy efficiency of screw compressors can be further increased by optimizing the flow conditions in the compression process. Improvements to the air inflow into the compressor unit have proven to be particularly effective in this regard. In AERZEN’s latest 5plus generation of machines, all components are precisely coordinated to ensure optimal flow behavior. The reduction in pressure losses and the improvement of the intake and discharge ports help ensure that the desired discharge pressure is maintained in a stable and reliable manner. The additional sound insulation not only reduces noise during operation but also optimizes flow characteristics.

Premium motors are available as needed to meet the requirements of current energy efficiency classes. Future-proofing is particularly important to customers in this context, as durability is also measured by whether or not future requirements regarding energy efficiency classes can be met.

Modern rotary compressors are easy to operate and maintain efficiently. Digitalization simplifies processes, increases transparency, and reduces additional follow-up costs. In addition, screw compressors generally experience less wear and tear. The result is robust, reliable, and easy-to-maintain machines for a wide range of applications.

The smooth-running V-belt drive on the 5plus generation machines allows for the installation of different pulleys to achieve the desired gear ratio. Changing the pulleys is also easy to do retroactively. The screw compressor remains flexible when the desired parameters change and does not need to be replaced with another model that has inflexible settings. Maintenance requirements for the V-belt drive are extremely low, as the correct tension is ensured by its own weight. On many units, the speed can also be controlled electronically.

High precision and exact maintenance of the desired pressure are an absolute must in most applications. Control can then be performed, for example, directly via an integrated control element on the housing. Because the control elements are located on the front of the units, the units can be arranged side by side to save space. With this design, it is even possible to check the oil level while the unit is running. Special AERZEN oils extend oil change intervals to twice the specified intervals.

A major advantage of screw compressors is their quiet operation. Unlike piston compressors, there is no need to stop masses at their respective dead centers, which results in significantly lower vibrations inside a rotary compressor. This quiet operation can be further optimized through design measures. At the same time, intelligent sound insulation offers additional benefits for safety- and hygiene-critical applications.

The use of an innovative silencer design reduces the sound pressure level. It also serves as an effective spark arrestor. Machines equipped with this feature are also approved for use in explosion-protected areas. Thanks to its optimal sound-dampening properties, no additional sound-insulation materials are required. This eliminates the risk of contamination from damaged insulation materials or similar sources. The associated maintenance work is also eliminated.

Particularly in hygiene-critical areas of the food industry and in chemical plants, effective sound insulation without the risk of contamination is a key requirement in addition to the need for oil-free compressors. Where necessary, a compressed air filter can be used to further purify the compressed air. In the medical sector, special filters for treating compressed air are just as common as separation systems for other residues. To prevent unwanted moisture from entering the application area, aftercoolers and dryers ensure effective dehumidification of the compressed air.