A rotary-screw compressor, like an air compressor, utilizes a rotary-type positive-displacement mechanism to compress gas. These compressors are widely used in industrial settings and serve as replacements for traditional piston compressors when dealing with larger volumes of compressed gas. They find applications in various scenarios, such as powering air-driven tools like jackhammers and impact wrenches or in large refrigeration cycles like chillers. However, when it comes to smaller compressors, the leakage in the rotors becomes more significant, making piston compressors a more suitable choice.
The screw compressor closely resembles the screw pump, with the key difference being the progressive reduction in the size of trapped material pockets along the screw. This design feature enables the compression of the material within the pockets. As a result, the screw in a screw compressor is asymmetrical along its length, whereas a screw pump remains symmetrical throughout.
Unlike piston compressors, the gas compression process in rotary screw compressors occurs through a continuous sweeping motion. Consequently, there is minimal pulsation or surging of flow, leading to quieter operation and reduced vibration, even at larger sizes. This smooth operation offers advantages in terms of efficiency as well.
Rotary-screw compressors find their primary application in supplying compressed air for larger-scale industrial needs. They excel in situations where there is a continuous demand for compressed air, such as in food packaging plants and automated manufacturing systems. However, even with a sufficient number of intermittent demands and storage, they can effectively handle the workload as long as it maintains a suitably continuous load. These compressors come in fixed units, but they are also frequently mounted on tow-behind trailers and powered by small diesel engines. Such portable compression systems are commonly referred to as construction compressors. Construction compressors play a crucial role in providing compressed air for various tasks like operating jackhammers, riveting tools, pneumatic pumps, sandblasting operations, and industrial paint systems. You can often spot them at construction sites or accompanying road repair crews worldwide.
Screw air compressors are also widely utilized in the mining industry, specifically on rotary, DTH (Down The Hole), and RC (Reverse Circulation) drill rigs used for production and exploration drilling applications. They also find application in oil and gas pipeline services, such as pneumatic testing or air pigging, where they assist in maintaining and operating the pipelines effectively.