Modern air compressors for pneumatic systems
Pneumatics is a section of science, engineering and technology that deals with the study and application of pressurised air (or alternative pressurised gas such as pressurised nitrogen) to produce mechanical motion, control action and actuations. In other words, a pneumatic actuator or device converts energy (in the form of compressed air) into mechanical motion. The motion can be rotary or linear, depending on the type of actuator (or device). Advantages of pneumatic systems are: • Simplicity of design and control. • Reliability, pneumatic systems generally have long operating lives
and require little maintenance. • Operational benefits, for example, because air is compressible, actuators or equipment is less subject to shock damage. Air absorbs excessive force, whereas fluid in hydraulics more directly transfers force. Compressed gas can be stored, so machines still run for a while if electrical power is lost. • Safety – there is a very low chance of fire compared to hydraulic oil or electrical systems. Newer and modern machines and devices are usually overload safe. The equipment, instruments, actuators, control systems and tools which run on compressed air are extremely critical for modern plants and units. The compressed air could be one of the most expensive utilities considering the amount of valuable energy consumed to compress the air and complex drying and filtration systems used. Sometimes, because of an inefficient air compression system, poor air-system energy management, improper capacity control and other reasons, more than 50 percent of the energy used in air compression is wasted. Generally, the issue of the energy efficiency is overlooked in air compressor packages.
Modern air compressor technologies will be discussed in this article; there is a great market available for turbo-compressors in air services. Integrally-geared centrifugal compressors and directdriven centrifugal compressors (using oil free bearings such as magnetic bearings) for air compression applications are discussed.
Plant operators strive to improve the cleanness (particularly elimination of the oil carryover) of the air in units and factories since even a small amount of oil, liquid or dirt in many instruments or actuators can lead to serious problems. Considering this fact, it should be point out that all positive displacement compressors are involved (in some extent) mating-part rubbing, sliding, friction or liquid sealing which could result in oil, liquid or particle carryover by the compressed air. The selection of the air compressor depends on factors such as capacity, discharge pressure, required air quality, and ambient conditions. and in such cases turbo-compressors would be a better option.