Summary of knowledge points of screw air compressor
Classification of screw air compressor
Screw compressors are also called screw compressors, which are divided into single screw compressors and twin screw compressors. The single screw compressor was developed by Sinn, France in the 1970s. Because of its more reasonable structure, it was quickly applied to the national defense field and protected by developing countries. The technology has always been relatively independent. The twin screw compressor was first proposed by the German H. Krigar in 1878. It was not until A. Lysholm of the Royal Institute of Technology in Sweden that the screw compressor SRM technology was established in 1934, and it began to be applied in industry and achieved rapid development.
Characteristics of screw air compressor
Screw air compressor is currently a more popular and suitable model. It will replace the traditional piston air compressor. Among all users of Fidelity screw air compressors, the feedback on screw air compressors is better. , Mainly because screw air compressors have more advantages compared with other types of air compressors:
(1) Product specifications are relatively easy. Within a certain range of air volume, the diameter and shape of the rotor can remain unchanged, and only the screw rotor needs to be lengthened and shortened to meet the needs of different air volumes. This feature can reduce manufacturing costs to help market competition ability.
(2) Like reciprocating air compressors, it has the same characteristics as fixed-displacement air compressors, and the exhaust pressure has a wide range of changes.
(3) The structure of the screw air compressor is not complicated, and the performance of continuous use is quite good. At the same time, compared with the reciprocating air compressor, it greatly reduces a lot of consumable parts and has the advantage of easy maintenance.
(4) The noise level of screw air compressor can be said to be the highest z* among all air compressors. The noise level depends on the air volume, and often exceeds 100dbA. Therefore, screw air compressors must be equipped with soundproof covers. It also gives a good impression of more beautiful appearance.
(5) Throttle control can be used.
(6) Oil-injected screw air compressors have good shaft seal airtightness, while centrifugal compressors used for high-speed shaft seals cannot achieve 100% airtightness, so they are not suitable for the compression of any gas other than air or nitrogen.
It is impossible for any product to be perfect. Of course, screw-screw air compressors also have some shortcomings:
(1) The gap that must exist between the female and male screws, resulting in unsatisfactory air tightness, is the main reason for the poor energy efficiency of oil-free screw air compressors, and it can even be said to be various types of air compressors with the same volume. The worst of all; the oil-injected screw air compressor solves this problem, but the pressure loss caused by its oil filter adds a certain percentage of energy consumption.
(2) The oil-free screw compressor body only has a life span of 3-5 years, and the technology for replacing the air compressor body is often retained by the original manufacturer. Therefore, the cost of replacing the entire set of air compressor bodies will generally exceed the purchase Sixty percent of the new machine is also a big criticism from users of this type of air compressor.
(3) The oil-injected screw air compressor is shut down for a long time after long-term operation, and the rotor stuck in the air compressor (mainly due to the precipitation of grease in the lubricating oil) is commonplace, and the standby air compressor becomes an extremely unreliable standby status.
(4) The compressed air of the oil-injected screw air compressor contains oil, which is not suitable for the food industry.
(5) Oil-injected screw air compressors have high requirements on the quality of lubricating oil. Regular maintenance such as lubricating oil replacement and filter replacement are required, and the maintenance cost is high.
The use of screw air compressors can increase productivity, shorten working hours, and make maintenance and care easier for enterprises (etc.)
Air compressor failure
Common failures and treatment of air compressor system
The power air source of the first pneumatic ash conveying system and the air system for heat engine instrumentation and equipment maintenance use (oil injection type) screw air compressor for air supply, and a dryer is installed at the outlet of the air compressor (for drying, degreasing, Dust removal to prevent blockage of the ash pipe caused by water in the compressed air).
The free air output under the rated pressure of the air compressor is 42.7 to 33.2 m3 /min. The minimum working pressure is 5bar. The maximum or rated working pressure is 7.5bar to 13bar. The motor output is 250 KW. Below 1℃, the internal pressure (ie point ② pressure) is not higher than 0.4bar Working principle: Screw air compressor is a positive displacement compressor, which achieves the purpose of gas compression by gradually reducing the working volume.
It consists of a pair of tooth slots of the rotors which are placed parallel to each other and meshed with each other and a shell containing the pair of rotors. When the air compressor is running, the two rotors are inserted into each other's slots, and as the rotor rotates, the teeth inserted into the other's slots move to the exhaust end. The volume enclosed by the other teeth gradually decreases, the pressure gradually increases, and finally the exhaust Vent the air out.
二 Air compressor alarm, failure and treatment
㈠, the common alarms of air compressors are:
1. High temperature: Refers to the temperature of the oil and gas mixture at the outlet of the compressor, which is greater than or equal to 110°C and alarms and 120°C trips.
2. The pressure is too high: Refers to the compressor outlet pressure, which is higher than 10bar to alarm and 15bar to trip.
3. Oil and gas separator: The compressed air from the compressor head entrains oil droplets of various sizes. Large oil droplets are easy to separate when passing through the oil and gas separation tank, while small oil droplets (suspended oil particles below 1um in diameter) must be filtered through the micron and glass fiber filter layer of the oil and gas separation filter. So that the compressor discharges more pure and oil-free compressed air. The solid particles in the compressed air pass through the oil core and stay in the filter layer, which causes the pressure difference (resistance) of the oil core to increase continuously. With the increase in the use time of the oil separation core, when the pressure difference of the oil separation core reaches 0.08 to 0.1Mpa, the filter element must be replaced.
4. Air filter: When the air filter is dirty or blocked, the resistance of the air passing through the filter increases and negative pressure is generated at the compressor inlet.
5. Oil filter: Due to the long-term operation of the air compressor, the impurities in the air are sucked into the compressor, which causes the oil filter to be dirty and clogged, which makes the pressure difference between the front and back of the oil filter too large.
6. High oil temperature: Due to the long-term operation of the air compressor, the oil quality is aging, the oil return path is not smooth, the oil filter is blocked, and the compressed air from the air compressor will entrain a small part of the oil and cause the loss of air compressor oil. The oil temperature is high.
7. High exhaust temperature: It means that the air compressor has poor heat dissipation, and the air compressor oil volume and oil quality are abnormal.
8. Low oil level: Refers to the low oil level in the oil-air separator of the air compressor, and no oil can be seen in the oil level gauge.
9. Pipeline pressure: The load/no-load control of the air compressor exceeds the operating pressure of the machine.