Air compressor is a common power equipment, which converts mechanical energy into gas pressure energy. Its main function is to provide gas for production. Air compressor is widely used in production, mainly in air separation unit, biological fermentation, textile, metallurgy and mining, wind tunnel test, instrument control, military and other fields. The effect of air compressor operation largely depends on the air compressor selection and technical parameters.
1、 Brief introduction of air compressor type
According to the structure type of the rotor, the air compressor can be divided into screw type air compressor, centrifugal air compressor, piston air compressor, axial flow air compressor, mixed flow air compressor, rotary air compressor and slide type air compressor. According to its working principle, it can be divided into screw air compressor, piston air compressor, rotary air compressor and slide type air compressor. All of them belong to volume type, which directly rely on changing the gas volume to improve the gas pressure machinery; Centrifugal air compressor, axial flow air compressor and mixed flow air compressor are all of the speed type (or power type). The gas passing through it is accelerated by the blades of high speed rotation, so that the speed can be converted into pressure.
Different types of air compressors have their own characteristics and different use occasions. Screw air compressor is mainly used for the preparation of instrument gas in industrial processing occasions; Piston compressor is mainly used in places with high air pressure; Centrifugal air compressor and axial flow air compressor are mainly used in air separation unit, metallurgy and chemical industry, biological fermentation and other fields because of their large exhaust volume. In recent years, frequency conversion technology and permanent magnet technology have been applied to the field of air compressor, which greatly improves the stability and economy of air compressor operation.
2、 The principle of air compressor selection
As an important power energy supply facility in industrial production, air compressor selection should be based on the principle of safety, reliability, economy and efficiency, low installation and maintenance cost in order to ensure its safe, stable and efficient service production.
Firstly, according to the air pressure and air flow required by the user, the air compressor of the appropriate structure type is selected. The mechanical performance (low vibration and low noise) of the air compressor is good when working, and the adaptability is good under the changing working conditions, and can be operated stably and continuously, which is the basis of air compressor selection; Secondly, the economy of air compressor system operation should be regarded as an important index of air compressor selection, which includes the comprehensive indicators of unit power consumption (kwh/km3) or steam unit consumption (t/km3), quality of desuperheating water required by air compressor, water consumption (t/km3), and residual heat benefit of air compressor; In addition, the selection of appropriate air compressor technical parameters (exhaust volume, exhaust pressure) is the premise whether the air compressor can meet the production demand and whether it is economically operated; Finally, the air compressor installation and maintenance cost should be one of the indicators of air compressor selection, and the air compressor with simple installation and low maintenance cost should be selected as far as possible.
The selection of air compressor shall be carried out according to the following procedures:
(1) Investigate the user requirements (air pressure, air flow, air temperature, air humidity, etc.) required by the user;
(2) Calculate the resistance between the air compressor outlet and the user point;
(3) Determine the rated exhaust pressure of the air compressor (the rated exhaust pressure of the unit can be calculated according to 1.1 times of the theoretical data), the exhaust volume, the exhaust temperature of the air compressor after the aftertreatment device, etc;
(4) According to the requirements of automatic operation of the unit, the appropriate electric control and automatic control system are selected;
(5) Draft technical requirements of air compressor and prepare for procurement;
(6) The air compressor manufacturer and users are investigated on the spot, and the production level and production capacity of the manufacturer are found out, and the real feedback of the air compressor users can be deeply understood;
(7) The air compressor is purchased by bidding, and reasonable scoring standards are formulated. The air compressor units with high cost performance are selected through bidding;
(8) After the equipment contract is signed, the face-to-face technical documents shall be butt connected with the air compressor supplier to form the air compressor technical agreement as an attachment to the contract.