Screw compressors are some type of gas compressors that use two interlocking screws to capture and compress gas. Screw compressors are of two types, the dry running screw compressor, and the oil-flooded screw compressor. Lubricating oil is used in the oil-flooded compressor to facilitate the screwing process. The oil also provides a hydraulic seal that passes energy between the screws.
In the dry running compressor, male and the female rotors maintain a special alignment in a timely manner, such that, one screw drives the other to form a continuous rotation of the screws (Bloch and Soares 76). The interaction of the male-female thread traps air, compresses it, and converts it into energy.
In both types of screw compressors, the air enters through the suction point; the rotors compress it while they rotate, and it finally gets its way out through the outlet as energy. Unlike other compressors that are somewhat noisy, screw compressors are noiseless and they compress air continuously.
The first step in operating a dry running screw compressor is ensuring the power unit has a strong cooling system. Two-screw gear units inside the chambers are shaped differently, but in a manner that they interlock perfectly. While rotating, the screws suck and trap air as they rotate from one end.
The rotation of the screws reduces the size of the chamber and this facilitates the compression process. As the screws rotate, they push the compressed air forward to the next screw to allow the sucking of new uncompressed air. The highly compressed air forces itself out at the discharge point. Compressors work differently depending on whether they are oil free or oil flooded.
There is no oil lubrication in the oil free compressors; thus, the movement of the screws compresses the air without necessarily depending on the oil seal. Such compressors do not give high-pressured power. However, there are multistage compressors that give high-pressured power by compressing air at several screw sets. In the first stage, air is compressed into a few bars to become light and extremely hot.
The light air will thus moves to the succeeding screw bars easily. Every move of the air makes it extremely hot, and this continues until the air reaches the outlet point. In most case, oil-free compressors are made up of about seven bars. For the oil-flooded compressors, users inject oil into the screws. As the screws rotate, the oil finds its way onto the sealing of the cavities to provide some cooling effect.
The oil is also useful in capturing particles in the air during the air sanction process. When the compressed gas gets its way into the discharge end, any oil that is present in the air is filtered and recycled. However, this is not an assurance that the compressed air is free from oil traces.
The applications of screw compressors vary from construction to industrial applications. Oil-injected screw compressors are used in industries that require large volumes of compressed air. Moreover, industries that operate high-powered tools would find it worthwhile to use screw compressors to generate the required volumes of compressed air instead of using piston compressors.
Contractors can also use oil-injected screw compressors to operate the construction machineries, whereas, the wastewater treatment machineries also find it worthwhile to use such compressors in their process because they consume low power. In the case of medical researches, dry running screw compressors would be of great use.
A lobe compressor has some similarities with the screw compressors, only that the screws in the screw compressors are replaced with lobes. A lobe compressor has two 8-shaped profiled lobe blowers. The 8-shaped lobes rotate inside some somewhat oval casings. The lobes are always 900 apart at any instance whenever they are in operation. The distance between the two lobes allows them to hold as much air as possible.
During operation, one of the lobes acts as the driver. It obtains is power from external sources while the other lobe relies on it to rotate. The oval casings and the system pressure do not allow the discharged air to came back unless under very small spillages.
However, the spillages are negligible, as only small amounts of air would be allowed in case of a slip. With the air coming and going out, there is no change in the volume of the air within the machine. The system’s pressure at a particular time draws in air, compresses it, and lets it out as compressed power.
The air across the machinery determines the temperature levels of the discharged air. It is noteworthy that lobe compressors do not require oil lubrications within the lobes. The lobes run for restricted clearances to deliver compressed air that is free from oil spillages.
As discussed, lobe compressors discharge compressed air that is oil free (Stosic, Smith and Kovacevic 69). Therefore, lobe compressors are used in fish hatcheries and aquacultures to support life.
They are also useful in meat processing systems as they produce compressed air that is free from harmful chemicals. People have also found lobe compressors useful in the printing and paper converting industries, wastewater treatment industries, and in the environmental remediation systems.
Bloch, Heinz. A Practical Guide to Compressor Technology. Hoboken, NJ: John Wiley & Sons, 2006. Print.
Bloch, Heinz, and Claire Soares. Process Plant Machinery. New York: Elsevier Publishing, 2008. Print.
Stosic, Nikola, Ian Smith, Ahmed Kovacevic. Screw Compressors: Mathematical Modeling and Performance Calculation. New York: Springer Publishing Company, 2005.Print.