Rotary Screw Compressor: Why Engineers Ain’t Pressed for Words
Compressed air was considered something free once upon a time, but those days are gone. We know that it is considered a fourth utility that shouldn’t be wasted so freely. The air should be dry, clean and it should come in a box that doesn’t make much noise.
Over time rotary screw compressor designs have changed to meet the high demand of industrial plants. It has evolved over time from a simple circular profile to an asymmetric profile. This has improved the efficiency and leakage in the discharge area. Size usually has a major role in leakage so efficiency is always greater in a smaller rotary screw compressor.
A rotary screw compressor uses two rotors in order to push air through the compressor which is what creates pressure. This compression is achieved with the first and second rotors synchronously meshing inside a dual bore house. The difference between the two rotors is that the first one has lobes and the second has grooves that intertwine with each other, most people refer to them as male and female. There is also an air inlet port where air flows in and a discharge port where everything flows out. There are some designs that include oil or water to remove heat from the compression process and prevent the rotors touching. There are many different stages that all increase efficiency and generate higher pressures. Watch the video below if you want a basic rundown of how this machinery works.
There are three main types of basic drives a rotary screw compressor – a V-belt, direct, and gear. Which one is chosen depends on different factors which include the speed required and the manufacturers preferences. A V-belt drive allows a smaller footprint in the enclosure, alignment is not a critical element and maintenance is simple. A direct drive has built-in alignment, the need to maintain the belt and gear are eliminated while the footprint of this machine might be larger as it is quiet. A gear drive has no issues with alignment and is generally used for higher horsepower, the compressor speed can also be of different speed from the motor.
Capacity control is used to regulate the air output when the unit itself is operating below the full load capacity. The control system allows the compressor to only produce the required amount of air which lowers the amount of power it wastes. Before variable speed drives became popular, there was nothing else that operated this way. This is the most energy efficient option as well as being a great leap forward in technology.
Many rotary screw compressors have electronic control panels. These are user-friendly and you can adjust them to your needs. Maintenance is so much easier as these panels can tell you which filters, separators, or oil you need to replace. The installation process is quite simple, you only need a concrete foundation big enough to support the mass and provide alignment between the compressor and driver. You may need to bolt the foundation in place depending on how it was designed. Maintenance is another important factor of a rotary screw compressor. There are generally five areas of a compressor that you need to keep an eye on and that may need regular maintenance. These five are the air-end, motor, dive train, lubricants, and filters.
Rotary screw compressor is a vital piece of technology for many industries and has evolved many times over the years. It is the one piece of equipment that will continue to get better as technology moves forward.