General mechanical equipment air compressors are widely used in various fields of industrial production, such as supplying air to pneumatic valves as a power source, and providing pure compressed air for medicine and food fermentation. According to different structures, it can be divided into screw type, centrifugal type, piston type, sliding vane type and so on.

Among them, the screw air compressor is a high-speed rotary positive displacement compressor, which performs gas compression by reducing the working volume. Except for two high-speed rotary screw rotors, there are no other moving parts.It has advantages that centrifugal and piston compressors do not have. For example, small size, light weight, stable operation, few wearing parts, high efficiency, large single-stage pressure ratio, stepless energy adjustment, etc., which have developed rapidly in recent years, replacing piston air compressors in many fields.

1. The structure and principle of screw air compressor

The main components of screw air compressors include screw main engine (air end), air filter, suction control valve, solenoid valve, one-way valve, oil cylinder, oil and air separator, pressure valve, air cooler, temperature control valve, Oil filter, oil cooler, oil shut-off valve, etc. From the perspective of operating principle, the work of screw air compressor is divided into three main processes of suction, compression, and exhaust, as well as auxiliary processes such as sealing and conveying of compressed media. First, the intake valve is opened, and the air compressor sucks in the surrounding air through the intake filter to make it enter the compression main engine. The female and male rotors change the volume in the main engine through meshing motion. At the same time, the cavity is continuously sprayed with lubricating oil to lubricate the screw. Cooling, resulting in a heated compressed oil and air mixture. The heated and pressurized oil and gas mixture enters the oil and air separator through the exhaust one-way valve. Most of the oil in the main engine cavity is separated from the compressed air in the oil and air separator, and then returned to the main engine for recycling after cooling. When the air in the oil-air separator reaches the required minimum pressure, the minimum pressure valve opens, and the high-temperature compressed air enters the cooler to cool, and then the compressed air we need is obtained. After reprocessing by the post-processing equipment, it enters the public pipeline network. Or the user's air equipment

2. Maintenance of screw air compressor

(1). Maintenance and replacement of air filter element

(2). Maintenance and replacement of lubricating oil

(3). Maintenance and replacement of oil filter

(4). Maintenance and replacement of oil and gas separator

3. Common failures and countermeasures of screw air compressors

1. The exhaust temperature of the unit is high

(1). The temperature sensor is out of order. Countermeasures: It is recommended to replace;

(2). Lubricating oil specifications are incorrect or deteriorated. Countermeasures: Check the oil number and change the oil product. The old oil must be completely drained before injecting new oil;

(3). The lubricating oil level of the unit is low. Countermeasures: Oil should be added to 1/2-2/3 of the sight glass;

(4). The temperature in the computer room is high. Response measures: strengthen indoor ventilation;

(5). The oil filter is blocked. Response measures: dismantle and replace;

(6). The cooler is blocked and the heat exchange is poor. Countermeasures: check and clean the cooler;

(7). The cooling fan is malfunctioning. Countermeasures: troubleshoot or replace the fan.

2. The exhaust temperature of the air compressor is lower than the normal value

(1). The ambient temperature is too low. Countermeasures: reduce the heat dissipation area of the cooler;

(2). The empty car is too long. Countermeasures: increase air consumption;

(3). The temperature sensor is faulty. Response measures: adjustment or replacement;

(4). The temperature control valve fails. Response measures: replacement;

(5). The oil flow is too large. Countermeasures: reduce the oil flow control valve.

3. The exhaust gas has a large oil content, and the lubricating oil addition cycle is short

(1). The oil level is too high. Countermeasures: Check the oil level and discharge it properly, the oil level is at 1/2-2/3 of the sight glass;

(2). The oil return line is blocked. Response measures: disassemble and clean;

(3). The check valve of the return pipe is damaged. Response measures: replacement;

(4). The exhaust pressure is too low when the air compressor is running. Countermeasures: adjust the pressure switch to the set value;

(5). The oil-gas separation filter element is damaged and invalid. Response measures: replacement;

(6). The pressure maintains the fatigue of the valve spring. Countermeasures: Replace with new springs.

4. The air compressor has a large starting current and trips

(1). The problem of starting the air switch. Response measures: overhaul or replacement;

(2). The input voltage is too low. Countermeasures: adjust the input voltage;

(3). The star-delta conversion time is too short. Countermeasures: reset the interval time;

(4). The host or main motor is faulty. Countermeasures: The belt can be removed or the connection with the motor can be disconnected, and the manual cranking can be turned several times to check whether the main engine is locked or the friction is large;

(5). The intake valve is too open or stuck. Response measures: regular maintenance and replacement of the intake valve repair kit;

(6). The wiring is loose. Countermeasures: Check for signs of heat generation and re-wiring.