Main Fault Analysis and Solution of Air Injection Screw Air Compressor
At present, in many mechanical industries in China, screw air compressors are being widely used. If the actual operation of the screw is not accurately judged and the possible failures are predicted in time, it may cause the screw. There are a lot of problems in the air compressor, which is difficult to operate and use normally and smoothly. Therefore, it is very important to analyze the failure of the screw air compressor in detail and propose effective and effective treatment methods to ensure the normal and smooth operation of the screw air compressor.
Fuel injection screw air compressor advantages
1Injection twin-screw air compressor has the advantages of high stability, high efficiency, low vibration and low noise.
2 The yin and yang rotor and the cooperation between the rotor and the casing are set, so that the gas has less backflow leakage and no residual gap volume, so the efficiency is high.
3 The injected lubricant has sealing, cooling and lubrication
4 Small parts, no suction, exhaust valve plate.
1. Host: World* brand, excellent performance and reliable operation.
2. Motor: Class F air-cooled motor efficiency exceeds EFFL standard.
3. Transmission system: The motor drive end is applied with compressor oil lubrication, high efficiency, maintenance-free and extremely high reliability.
4. Fan: The cooling air volume is large and the noise is low.
5. Heat dissipation system: It adopts plate-fin structure and high-quality materials to ensure the pressure resistance of the cooler, high heat dissipation efficiency and good corrosion resistance.
6, air filter: heavy-duty, multi-stage air inlet filter, dust removal accuracy of 1um (99% filtered), large contact surface, long service life.
7. Oil/Gas Separator: The new generation of separators uses a new filter material that is more efficient and has an air content of less than 1 ppm.
8. Intelligent controller: All operations and related data of air compressor operation are displayed on the control panel, and it is easy and convenient to control between your fingers.
High performance, high efficiency
Air Compressor Equipment - The screw air compressor uses a high-capacity compression assembly. The rotor has a low outer circle speed and achieves good oil injection, achieving high efficiency and high reliability. The new zui design ensures extremely low system temperature and compressed air temperature. Ensure that all components achieve a good cooling effect and a long service life.
Maintenance-free, highly reliable and efficient drive concept
Air Compressor Equipment - The screw air compressor drives the compression assembly at a high speed through the high efficiency transmission system at a suitable speed. No maintenance is required during normal operation.
Low maintenance costs
Air Compressor Equipment - The original compressor design of the screw air compressor saves unnecessary maintenance costs. All components are designed for long life, and large inlet filters, oil filters and fine separators ensure good compressed air quality. All oil filters and separator units of all models up to 22 kW (30 hp) are centrifugally opened and closed, reducing maintenance time. The "Speedup Service Point" allows maintenance work to be completed in minutes, with reduced downtime and maintenance costs.
Built-in intelligent control
To reduce operating costs, sophisticated operational controls are essential. All machines are equipped with an intelligent control system, and the control menu is easy to use.
However, it may also have problems such as over-temperature, high operating current and insufficient air volume during operation. Now we focus on the analysis of the causes of over-temperature faults in screw air compressors, study their solutions and preventive measures, and propose other common fault handling methods.
Analysis of the cause of overheating failure
Under normal circumstances, the exhaust temperature of the screw main unit should be between 75 and 95 °C. When the exhaust gas temperature is lower than the pressure dew point, condensation will occur, which will cause more moisture in the system, and the lubricant will be emulsified, which will affect the lubrication effect. Excessively high exhaust temperatures can cause damage to many components and severely burn the mainframe. The screw air compressors are designed with ultra-high temperature protection. Once the exhaust temperature exceeds 100 °C or the set temperature, the temperature sensor commands the temperature switch action, an alarm is issued and the machine stops automatically, and the exhaust temperature can be read on the instrument panel. More than 100 ° C.
The machine's own cooling measures are to spray lubricating oil from the lower end and the left and right ends of the body into the compression chamber, and participate in compression together with the inhaled air, and then discharge from the bottom of the main machine to the oil and gas barrel. In addition to lubricating the screws and bearings, gears and other parts, it also has a large amount of tropical. However, when the heat has not been transferred, it needs to be cooled by the oil cooler before the next injection operation to completely cool down. Therefore, the occurrence of over-temperature faults is mostly related to the abnormality of the lubrication and cooling system. The following analysis:
1. Insufficient amount of lubricating oil or abnormal operation of the oil circuit components will increase the oil temperature, causing over-temperature failure. E.g:
(1) Insufficient oil supply: First check if the oil filter and oil fine separator are clogged. Next, check if the oil regulator is normal. If necessary, increase the fuel injection amount.
(2) The oil stop valve is not working properly: the oil stop valve is generally two-position two normally closed solenoid valves, which are opened at start-up and closed during shutdown to avoid oil from the oil and gas barrels continuing to be injected into the machine head during shutdown and from the intake air. The mouth spouted.
(3) The malfunction of the thermal control valve: The thermal control valve is installed in front of the oil cooler, and its function is to maintain the exhaust temperature of the head above the pressure dew point. The main reason for its failure is that the elastic modulus of the two thermal springs on the valve core changes after fatigue, and can not move normally with the temperature change; the second is that the valve body is worn, the valve core is stuck or the action is not in place and cannot be closed normally. . Can be repaired or replaced depending on the situation.
(4) The lubricant specifications are incorrect or of poor quality.
2. Air suction, scheduling and control of components of the pipeline components can cause malfunction of the air compressor and cause over-temperature faults.
(1) Check if the air filter is clogged. It can be checked or replaced according to the alarm signal of the differential pressure switch.
(2) Check if the pressure is too high. The system pressure is generally set at the factory. If it is necessary to adjust, it should be based on the rated gas pressure of the equipment nameplate. If the adjustment is too high, overheating may occur due to an increase in the load of the machine.
Lubrication system and oil circuit components common faults
Insufficient amount of lubricant or abnormal operation of the oil circuit components will cause the oil temperature to rise, causing an overtemperature fault.
1. Insufficient oil supply, first check if the oil filter and oil separator are blocked.
The oil fine separator is made of multi-layer glass fiber, and the filtration precision can reach 0.1 μm, which is used to filter the oil mist in the compressed air to prevent the loss of lubricating oil. The environment is poor. When there is more dust, the replacement cycle should be shortened appropriately. The oil filter and the oil separator are designed with a differential pressure switch. The pressure difference between the two ends of the filter can be automatically determined to determine whether the filter is clogged. If the filter is clogged, the filter and separator should be replaced in time. Next, check if the oil regulator is normal. If necessary, increase the fuel injection amount. The amount of fuel injected has been adjusted at the time of shipment from the factory, and should not be changed under normal circumstances.
2. Thermal control valve work fails
The thermal control valve is mounted in front of the oil cooler to maintain the head exhaust temperature above the pressure dew point. The working principle is that when the oil temperature is low, the heat control valve branch is opened, the main circuit is closed, and the lubricating oil is directly injected into the machine head without the cooler. When the temperature rises above 67 °C, the thermal control valve is gradually closed. The oil flows through the cooler and branch at the same time and rises above 70 ° C. The valve is completely closed. The lubricating oil is completely passed into the machine head through the cooler, and the lubricating oil is cooled to a large extent. If the thermal control valve fails, the lubricating oil may enter the machine head directly without the cooler, so that the oil temperature cannot be lowered, resulting in over-temperature. The main reason for its failure is that the elastic modulus of the two thermal springs on the valve core changes after fatigue and cannot move normally with temperature changes. Second, the valve body is worn, the valve core is stuck or the action is not in place and cannot be closed normally. Can be repaired or replaced depending on the situation.
Lubricating oil quality deteriorates
The oil quality of the lubricating oil has a direct influence on the operating condition of the air-injection screw air compressor. Generally, the factors affecting the oil quality of the air compressor lubricating oil have the following points:
1. Inhalation of particulate matter containing iron oxide, carbon dioxide, etc. in the air to accelerate the deterioration of the lubricating oil;
2. During the oil change process, the air compressor fails to exhaust all the old oil and mixes with the newly exchanged oil, which affects the service life of the lubricating oil;
3. The operating temperature of the air compressor is too high to accelerate the oxidative deterioration of the lubricating oil;
4. The operating temperature of the air compressor is low, which causes the exhaust temperature of the air compressor to be lower than the dew point temperature. The moisture in the air is condensed and mixed into the lubricating oil to cause the lubricating oil to change.
Countermeasures:
(1) The suction port of the air compressor should choose a clean position as much as possible to reduce the inhalation of impurities and prevent the lubricating oil from deteriorating due to impurities;
(2) Strictly press the requirements of the air compressor manufacturer for the regular replacement of the lubricating oil, and regularly sample and analyze the lubricating oil to confirm whether the oil quality is normal and whether it is necessary to change the oil. It is not possible for economic reasons not to change the lubricant regularly as required, but only for regular filling. This will cause the viscosity of the lubricating oil to be too large, the heat dissipation performance will be deteriorated, and the temperature of the air compressor head will increase. At the same time, different grades of lubricating oil can not be mixed. When the quality and grade of lubricating oil are mixed, the performance of the lubricating oil will be reduced, and the viscous and deep deposits will be generated, which will block the lubricating oil system and affect the transportation of the lubricating oil. The press is faulty.
(3) Ensure that the head temperature of the air compressor is within the set range, and it is necessary to adjust the abnormal condition in time to avoid deterioration of the lubricating oil due to poor working conditions.
High fuel consumption
1. The oil level is too high
Reason: The oil level of the air compressor has certain requirements. If it is too low, the temperature of the air compressor head is high. If it is too high, the oil and gas discharged from the air compressor head cannot be completely separated. The oil content of the compressed air at the outlet of the air compressor is too high, and the fuel consumption of the air compressor is increased.
Countermeasures: Ensure that the oil level is kept within a reasonable range during normal operation to avoid such failures.
2.zui small pressure valve failure
Reason: The opening value of each manufacturer's air compressor Zui small pressure valve is pressure-regulated. For example, if the seal of the small pressure valve of Zui has a leak point, it is opened early or cannot be completely closed, the time for establishing the pressure of the air compressor oil separator zui is increased, the concentration of the gas oil mist at the low pressure state is high, and the flow rate through the oil is fast. The oil load is increased and the separation effect is reduced, resulting in an increase in fuel consumption.
Countermeasure: During the normal startup process, observe the boosting process of the air compressor, such as the normal pressure of slow boost or unable to boost, and the air compressor consumes high fuel, then the small pressure valve needs to be viewed and overhauled.
3. Oil separator failure
Reason: After the compressed air discharged from the air compressor head enters the oil separator, the oil and gas shells can be completely separated after two separations of the oil retaining plate and the oil separating core. If the oil baffle or the oil separation core fails or fails, the oil and gas may not be fully separated, resulting in high oil content of the compressed air at the outlet of the air compressor, and the fuel consumption of the air compressor is increased.
Countermeasure: The oil deflector needs to open the oil separator to check whether it is normal. The oil separation core can check whether it can run normally through the differential pressure between the front and the back. If problems are found, it needs to be replaced.
4. Return pipe failure
Reason: The lubricating oil separated by the oil separation core is deposited on the bottom of the oil separation core and sent back to the air compressor head through the oil return pipe. If the return pipe is blocked or faulty, this part of the lubricating oil will be taken out of the system by the compressed air, which cannot be recovered normally, which increases the fuel consumption of the air compressor.
Countermeasure: When the return pipe is blocked or faulty, the oil at the bottom of the oil separation core cannot be normal.
5. Oil cut valve failure
Reason: After the air compressor is out of service, if the oil shut-off valve is not normal or closed in time, the lubricating oil in the oil separator will flow back into the main engine of the air compressor, and then sprayed out from the suction filter, causing leakage of lubricating oil. .
Countermeasures: After each stop, observe whether the air compressor suction filter has leakage of lubricating oil. If there is any leakage of lubricating oil, repair the oil shut-off valve in time to ensure its normal operation and avoid a large amount of lubricating oil. vent.
Cooling system failure
The cooling method of the screw air compressor is water-cooled and air-cooled. It can be checked as follows.
1. Check if the oil cooler works normally.
For water-cooled models, the temperature difference between the inlet and outlet pipes can be checked. Under normal conditions, it should be 5-8 °C. If it is lower than 5 °C, there may be scaling or blockage. It will affect the heat exchange efficiency of the cooler and cause poor heat dissipation. At this time, the heat exchanger can be removed and cleaned.
2. Check if the cooling water inlet temperature is too high, whether the water pressure and flow rate are normal, and check whether the ambient temperature is too high for air-cooled models.
The inlet temperature of the cooling water should generally not exceed 35 ° C, the water pressure should be between 0.15 and 0.3 MPa, and the flow rate should be no less than 90% of the specified flow rate. The ambient temperature should not be higher than 28 °C. If the above requirements are not met, it can be solved by installing a cooling tower, improving indoor ventilation, and increasing the space of the equipment room. You can also check if the cooling fan is working properly, and if it is faulty, it should be repaired or replaced.
3. Air suction, scheduling and control pipeline components
Mistakes in the operation of such components can cause the compressor to malfunction and cause overtemperature faults. You can check by the following steps:
3.1 Check if the air filter is clogged
It can be checked or replaced according to the alarm signal of the differential pressure switch.
3.2 Check if the pressure is too high
The system pressure is generally set at the factory. If it is necessary to adjust, it should be based on the rated gas pressure of the equipment nameplate. If the adjustment is too high, overheating may occur due to an increase in the load of the machine.
3.3 Check if the intake valve works normally.
Due to the large fluctuation of the gas consumption in the pipe network, the intake valve controls its action through the volume adjustment valve to adjust the suction amount, and realizes no-load or load operation through the solenoid valve, thereby achieving the purpose of energy saving.
to sum up:
The screw air compressor is over temperature, the running current is high, and the air volume is insufficient. These faults are common faults. The occurrence of these faults not only affects the normal production operation, but also increases the loss of spare parts, shortens the service life of the equipment, and accelerates the oil. Deterioration, such as reduced lubrication performance, decreased flash point, and the like. Sometimes, high temperatures can cause self-heating of the oil, causing the air compressor to burn and even explode.
The cooling lubrication system, oil and gas separation system and gas volume regulation system of the screw air compressor are the key systems to ensure the normal operation of the unit. The probability of failure of these systems is about 80% of the total failure rate of the entire air compressor unit. The failure of the pressure unit is mostly caused by "two devices" (oil separator, air cooler), "three cores" (air filter element, oil separator filter element, oil filter element), "four valves" ( Intake poppet valve, zui small pressure valve, oil cut valve, temperature control valve). To ensure the normal operation of the air compressor unit, routine maintenance work of these components should be done. The "two devices" should be cleaned regularly, and the "three cores" should be replaced strictly according to the established maintenance plan, and an appropriate amount of spare parts for each valve should be reserved. As long as we strictly abide by the air compressor unit safety operation rules, timely maintenance, timely replacement of relevant accessories, increase the air conditioning unit ambient temperature and pressure and other parameters adjustment control, familiar with the handling of various common faults, can be guaranteed The pressure unit operates under the good conditions of Zui, providing a strong guarantee for production.
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