Have you ever wondered how a screw compressor works? Rotary screw compressors are highly versatile and modern machines that are an essential part of most industries.
How Do Screw Compressors Work?
Rotary Screw Compressors perform a myriad of industrial tasks and help to keep operational efficiency at its maximum.
So, let us take a look at the key parts and features that form part of this vital unit.
In terms of its function, a Screw Compressor (as its name suggests) compresses air. As the compressor condenses the air into a very concentrated form, it provides a seamless and consistent stream of air in order for various functions to be performed.
This stream of highly pressurized and dense air is made possible by the compressors two paired spiral rollers (or rotors). Each spiral shape roller is built inside a cylinder, and when they rotate, they facilitate the intake of air. As the air passes through these spinning chambers, it is compressed and pressurised as we explain further below.
The compressor screws both rotate so that air is compressed, trapped and held in the curved divots of the unit.
As the rotors interlock, they cause the air to become highly pressurised. This air then moves further along into the chamber where it is stored until it is discharged. These rotors can be considered the most critical parts of the machine as the Screw Compressor would not work without them.
The chamber of a Screw Compressor becomes smaller as the distance from the opening valve increases. This means that the trapped gas has less room, resulting in an increase in pressure. As the air compresses, it becomes more condensed, and once the pressured air has built up sufficiently, the discharge valve will open, allowing the pressurised air to move into a holding tank for later use.
The electrical operating system of a Screw Compressor is known as a control scheme. This controls the output of the units, a Variable Speed Drive (VSD) screw compressor can be programmed to either speed up or slow down its rotation speed, according to the desired amount of compressed air required.
The compression cylinder houses the rotors of the Screw Compressor. Input air will run through the chambers of the cylinder and into the two rollers. The number of cylinders that a screw compressor has will determine how many stages it has and the amount of pressurisation it is able to produce.
Cylinders also come in a wide variety: from single-cylinder units with only one motor to multi-cylinder compressors, which have dual-acting stages for 24/7 operation.
The inlet air filters are located inside the opening valve and function as dust, moisture, and harmful air particle catchers in order to protect the machine. In the case of an oil-lubricating compressor, separator elements are needed to sift any oil lubrication from the compressed air. Liquid lubrication in a Screw Compressor helps to cool the unit down and keep it operating at a safe working temperature.
On each end of the rotor, is a bearing. This helps the rotor to remain securely fastened and to rotate evenly. This also assists with load distribution. The bearings typically have anti-corrosive and anti-friction qualities as well as other design-specific features to increase output efficiency. Bearings are located in various places in the Screw Compressor and consist of both axial and radial-load types.
The suction valve is another crucial part that sits on top of the Screw Compressor. It takes in the initial and raw gas for the compressor. Depending on the stage control of the compressor, the suction valve will open to enable the external air to rush inside, where it will be trapped by the two rotors.
The Discharge valves sit on the opposite side of the suction valves. These are responsible for the final stage of the compression cycle. The discharge valves work to release the pressurised air into the storage chamber or out of the discharge pipe.
A Screw Compressor is powered by its motor: this part enables the rotors to turn, which then results in the unit being able to power the entire compression function. It is vital to assess the motor on a regular basis to ensure that it is functioning safely and optimally, as this can have an effect on the compressor as a whole.
The system control functions as a crucial display of the Screw Compressors general health, output, stop parameters, idling, and overall operational efficiency. When the unit is in use, the system control can be consulted to check on the functioning of the various compressor components.
Some Screw Compressors have intelligent, internal sensors that will automatically shut the screw compressors power off when the storage tank reaches full capacity or when its cycle is complete. This feature is handy, especially when you have large, unmanned operational requirements.
The storage tank or chamber receives condensed air from the discharge valve, where the air will remain at constant pressure until it needs to be used. Sizes of Screw Compressor storage tanks differ widely. For instance, when the compressor is used for a large-scale industrial application, it will be much larger than that of a personal screw compressor. Many large industrial storage tanks offer beneficial reserve features and enable the motor to rest for more extended periods.
In the case of oil-injection compressors, separator tanks are needed to prevent gas and oil from mixing, which would negatively affect the purity of the compressed air. Types of oil separators differ, and the Screw Compressor owner will need to modify (or reinstall another) oil separator as your unit ages or if you require the functionality to improve.
Seals and gaskets are also essential parts to a screw compressor as they ensure that the unit is sealed, well-locked, and free of leaks so that air pressurisation can take place. Of course, if the seals and gaskets are not functioning correctly due to wear and tear (or other causes), this will cause the pressurisation to drop.
It is vitally important to ensure that each component of your Screw Compressor is working well because even one small dysfunction can cause a loss of production or even a halt to your entire production.
