1. Working principle of screw air compressor
The main working parts of screw air compressor are: air quality filter, low-pressure rotor, intermediate product cooler, electronic motor, high-pressure rotor, aftercooler, transmission structure components, gearbox, regulator control management system, safety valve and silencer shell, etc.
2. Common faults and treatment
2.1 Air output temperature is too high
(1) Reduce the air input temperature. Increase the ventilation of the air compressor room of the enterprise, add exhaust hoods on the roof of the air compressor room to remove hot air, and control the indoor ambient temperature of the control system not to be too high, especially in the hot summer, the temperature of the air compressor room should not exceed 40℃.
(2) Reduce the input temperature of cooling water. The water temperature can be maintained at 18℃ in winter and 24℃ in summer. (3) Increase the flow of cooling water. According to calculations, the temperature difference between the input and output control temperatures of the cooling water system is 15°C, and the cooling circulation water flow rate is 3.7 liters/second. (4) Clean the scale or dirty sediment in the cooling water. Descaling agents can be added to the cooling water to dredge the cooling water system. 2.2 Oil temperature is too high The air compressor has an oil temperature protection setting. It will shut down when the oil temperature exceeds 70°C, resulting in frequent shutdowns of the air compressor. The reason for the high oil temperature is the failure of the oil cooler control. Since the cooling pipes in the oil cooler are relatively thin, it is not easy to clean after scaling, resulting in the inability to reduce the oil temperature. Replacing an oil cooler costs $2,800. After research, we took out the oil cooler, soaked it in detergent for a day, and then used a small water pump to press water into the oil cooler to repeatedly rinse and descale. Using this method, the air compressor in our company has not replaced the oil cooler, and the average oil temperature in summer can also be controlled below 60°C.
2.3 Frequent failure of air filter
When the compressor is put into use, the air filter can only be used for one month before it fails. After analysis, it is found that the surrounding air pollution environment is dirty. For this reason, a mesh cover (pre-filter) can be added above the air quality filter of the air compressor to extend the use time of the filter.
2.4 Other requirements for air compressor
(1) In summer, the ambient temperature of the air compressor room must be significantly lower than 40℃ before it can be turned on normally. When installing the air compressor, the distance between the machines should be greater than 2.5 meters to facilitate the heat dissipation and ventilation of the air compressor room.
(2) The compressor has two reference data: maximum working environment pressure and general management work and life pressure. When selecting an air compressor, the general work and study pressure should be used as a reference data to select the air compressor. If an air compressor with the largest working pressure is selected, it is easy to overload the compressor for a long time and burn the motor.
(3) Water-cooled air compressors have higher requirements for water quality standards. Common fault information is related to scaling of the cooling control system caused by poor water quality. Therefore, when installing the air compressor, a set of soft water treatment devices must be installed, which can greatly reduce the failure of the air compressor.
3. Twin-screw air compressor tripping treatment
Twin-screw air compressors have tripping failures during operation. Even during operation, the wind can be supplied normally, but sometimes it stops suddenly. First, we checked the motor part and found no obvious related problems; then checked the compressor temperature automatic protection and pressure automatic adjustment management system, and the temperature control part was normal. After disassembling and inspecting the pressure regulating valve and the unloading valve, it was found that the rubber membrane in the pressure reducing valve was damaged and there was a small hole on the membrane. Due to the damage of the rubber membrane, when the air supply pressure is constantly changing, the size of the air inlet of the air compressor cannot be adjusted in time, the unit workload does not match the diesel engine power, causing the diesel engine overload environmental protection tripping, and after replacing the rubber material film in the unloading valve, the fault can be eliminated.
Stop jumping immediately after starting, occasionally start normally, and stop jumping after working for a period of time. After inspection, the lubricating oil temperature and exhaust system pressure levels were not high. The temperature environmental protection switch was temporarily short-circuited, and the tripping phenomenon disappeared. This shows that it was caused by high temperature, but the heat emitted by the lubricating oil radiator could not be felt. The oil circuit of the lubrication system was checked, and the temperature environmental protection control switch and the temperature control valve were normal. The oil filter element was replaced and the heat sink was cleaned, but the fault problem still existed. During the disassembly inspection of the check valve, it was found that the rubber film was also damaged by the pressure difference before and after the lubricating oil. After replacement, the fault was eliminated. From this we can see that the tripping of the air compressor is often caused by the failure of a valve in the control system analysis due to the company's working pressure adjustment. The rubber seals, plastic diaphragms, springs and other parts of the valve are prone to failure, which are often hidden and easy to give people an illusion.