Screw compressor: the principle of operation, repair

Screw compressor is designed to reduce pressure by rotary movements of rotors. They refer to rotary compressor devices. Despite the fact that the equipment appeared in the mid-30's, it is now one of the most popular. Its main advantages are small dimensions, automatic operation, economy, etc. When it is installed, a special foundation is not used, since the vibration level is low compared to other models. The air-screw compressor forced out other types of vehicles. It is capable of compressing air up to 15 atmospheres. At the same time, the productivity reaches 100 m³ / min.

Advantages

Compared with other devices, the screw compressor has several advantages:

• Low oil consumption, which directly affects the quality of the supply air. It is used in a purified form for various pneumatic equipment. And the installation of additional filters is not required.
• Low noise and vibration. As stated earlier, due to the small dimensions, the installation is carried out without a special sound-absorbing foundation. This feature helps to equip various portable devices with air.
• The screw compressor is equipped with air cooling. It helps not only to cool different elements, but also to recuperate the premises by means of recycled heat.
• The ability to automatically operate, easy to install and operate. The equipment is controlled by means of special automatic systems.

disadvantages

Among the negative sides can be identified high cost and complexity of the design. In addition, the device requires additional equipment for the removal of hot air, which is necessary for heating the room. It is forbidden to use screw compressors in an environment with aggressive gases.

Screw compressor assembly

The simplest equipment has these elements:

1. A filter that serves to purify the air that enters the working element. As a rule, it consists of two parts. The first is installed on the housing, the second - before the valve.
2. Suction valve. When the compressor stops, it serves to prevent oil and air from escaping from the unit. It is controlled by pneumatics. In appearance, it is no different from a conventional spring valve.
3. The main part is a screw block. There are two connected rotors made of high-quality steel. The cost of such an element is quite large. Its design provides a thermal protection controller, which serves to stop the engine when the temperature reaches 105º degrees.
4. Drive unit. It consists of two pulleys installed in the engine and rotor, serves to increase or decrease the speed of rotation. The higher it is, the more air will be compressed. However, the working pressure is reduced.
5. The rotational speed of the rotor depends on the pulleys.
6. Motor. Rotational movements are carried out by means of belt transmission. It includes a thermal protection sensor that turns off the engine when high temperatures are reached. In addition, it prevents the emergence of various emergency situations.
7. The oil filter. Clears the oil for screw compressors before it enters the engine.
8. Oil separator. Serves to separate air from oil due to centrifugal force.
9. Oil separating filter. Clears the lubricant after separation from the air.
10. Safety valve. It works when the pressure in the oil separator exceeds the permissible values.
11. Thermostat. Regulates the temperature of the oil composition.
12. Oil cooler. After separation from the air, the oil enters a special container, where it is cooled.
13. Air cooler. To give air in the room, reduce its temperature to 20 degrees.
14. For blowing the aforesaid component is a fan.
15. Relay. Provides automatic operation of the unit, performs the function of the electronic control system.
16. To monitor the pressure inside the unit, a pressure gauge is installed.
17. The minimum pressure valve. It is in the closed position until the pressure exceeds the 4 bar mark.

The screw compressor is placed in the housing. It is made of high quality steel. Its surface is treated with a special substance that is not exposed to the effects of oil and other substances.

Screw compressor: the principle of operation

Air from the atmosphere gets through the valve into the rotary mechanism, before it is purified in the filter. Then, mixing with the oil takes place. Then it enters a special container for compression, while fulfilling the following objectives:

• Eliminates the gaps between the screws and the housing, so that the occurrence of leaks is minimized;
• Does so that both rotors do not touch each other;
• Removes heat, which is produced in the process of compression.

Compressed mixture enters the oil separator, where the separation into components occurs. The separated oil is cleaned in the filter and fed back to the unit, if necessary, it is cooled. Air is also fed into the air cooler, and then fed from the compressor.

What modes of operation exist?

The screw compressor, the principle of operation of which is described in the previous paragraph, can function in such modes:

• Start. In this mode, the screw compressor is started and connected to the mains by the "star" scheme. After a few seconds, he moves to the "triangle" scheme.
• Work mode. The pressure in the compressor starts to increase. When a certain mark is reached, the unit idles.
• Idling. In this mode, the rotor is rotated, during which the gas medium necessary for cooling air moves. It allows you to put the compressor in standby mode before turning off the unit.
• Standby mode. The screw compressor will perform this function until the pressure reading drops to the minimum value.
• Stop. When this mode is enabled, the compressor equipment goes to idle, and then completely turns off.
• Alarm-stop. It is used in the event that it is necessary to disable an air screw compressor urgently.

Repair the device

With good maintenance, the element can function for more than 50 thousand hours. Like any device, over time it is necessary to repair screw compressors. This equipment contains complex mechanisms and various complete sets. Quite often in this apparatus, electronics breaks down. Compressor plants have complex electronic systems that can burn out. Therefore, it is necessary to repair it, and in more complicated cases - to replace it. It can be done by highly qualified specialists. The cost of the control unit is quite large. If it has a dehumidifier, the repair of screw compressors will be even more expensive, since the equipment is a complex mechanism.

Cost

As previously stated, screw compressors are on the market in a very wide range. The cost depends on the capacity of the equipment, as well as technical characteristics. Its price range ranges from 250 to 700 thousand rubles.

Reviews

Many users of screw compressors note the high performance of the equipment. Since it has small dimensions, it can be used on different construction sites, without spending much energy during transportation. Among the shortcomings are high cost and complexity of the design.