Daily failure of screw air compressor

Screw air compressor has the characteristics of simple structure, small size and light weight. It has continuous exhaust, small exhaust pulsation, small vibration, and low requirements for installation foundation; few wearing parts, convenient use and maintenance; compact structure and stability Good, reliable operation, long life and many other advantages, it is more and more widely used in the mining industry and has become one of the main equipment that provides compressed air sources in underground production.

Screw air compressor nine common fault analysis-

1. High outlet temperature or exhaust temperature of compressor head

excessive temperature rise is a common fault in the operation of screw air compressors. Screw air compressors often run at high temperatures, which will seriously affect the displacement and service life of the machine. When the temperature rises too high, a high temperature shutdown failure will occur. The reasons are:

● Temperature sensor fault. Temperature sensor failure, will cause the PLC false alarm temperature is too high, causing shutdown.

● Ambient temperature factor. The head outlet temperature of the screw air compressor is generally set at about 110 ℃, while the outlet temperature of the head is equal to the ambient temperature plus 60 ℃. The ventilation environment under the pit is poor, and most of the high temperature is caused by this.

● Temperature control valve failure. When the compressor is cold-started, the temperature control valve can make the oil bypass the cooler and directly spray into the main engine head to accelerate the rise of oil temperature and prevent condensation in the compressor. After the compressor is running normally, it can adjust the flow through the cooler according to the oil temperature. The proportion of oil volume on the side of the road controls the oil injection temperature. If the temperature control valve is damaged or the action is not sensitive, a large amount of high temperature oil will not pass the cooler directly into the host head, resulting in high host temperature.

● Oil filter failure. The oil filter is used to filter the dust and impurities in the oil circuit. It is easy to be blocked after a period of time. After being blocked, the oil return is not smooth and the temperature of the host is high. (often appears at the moment of loading)

● Fault of oil cut-off valve. The fuel cut-off valve controls its reciprocating fuel injection through the air pressure of the gas storage tank. If a fault occurs, the oil circuit is not smooth, causing the oil temperature to be high; debris blocks the oil circuit or controls the gas circuit, causing the fuel cut-off valve to close and not spray oil, which will also cause The main engine head has high temperature due to lack of oil or poor heat dissipation.

● Insufficient amount of lubricating oil, dirty oil cooler, blockage, will cause the temperature is too high.

● The cooling fan fails, the air cooler is blocked, and the exhaust resistance is too large, resulting in poor heat dissipation and high temperature. The external dust and internal oil of the cooler shall be cleaned.

● The unloading pressure setting is too low, which causes the oil resistance of the air compressor during the unloading cycle to be too large, and the flow rate is too slow, which causes the heat not to be dissipated in time, thus causing the failure of high temperature shutdown. Therefore, the unloading pressure should be reasonably set (currently the pond pit is set at 0.6MPa).

2. The output exhaust pressure is too low

●If the actual gas consumption is greater than the gas production of the unit, check the connected equipment and pipe network, and repair any leakage point in time. If the air consumption of the system is greater than the air output of the compressor unit under normal use conditions, the compressor unit with large specifications should be replaced or increased.

● Unloading pressure set value is too low. Set the unloading pressure value correctly and give full play to the efficiency.

● The air filter element is dirty and blocked, resulting in insufficient air intake of the compressor unit and low exhaust pressure. The condition of the air filter should be checked and replaced if necessary.

● Solenoid valve failure. The main bleed solenoid valve and cold start vent solenoid valve on the exhaust pipe leak and need to be replaced.

● Control gas line hose leakage. Replace the control gas line hose.

● Intake valve action is not sensitive, not fully open. The control system needs to be overhauled and checked.

●The oil separator is blocked, and the oil separator filter element needs to be replaced.

● Leakage of safety valve. Valves need to be recalculated or replaced.

● The drain valve of the gas-water separator is jammed after it is opened, causing leakage, which should be overhauled.

● The vent valve fails and cannot be closed when the compressor unit is loaded. Repair or replacement is required.

3. The output exhaust pressure is too high

● Intake valve failure. Need to repair or replace.

● Unreasonable setting of loading and unloading pressure value. The loading and unloading pressure value shall be set according to the actual air consumption.

● Pressure sensor failure. Replacement.

● The unloading valve is not closed, the unloading valve is stuck or not closed tightly, and the solenoid valve fails. Repair the unloading valve and replace the solenoid valve if necessary.

4. Load unloading frequently.

● If the pressure controller's loading and unloading pressure difference is too small, reset the loading and unloading pressure value. (The current setting value of pond pit is: loading 0.5Mpa, unloading 0.6Mpa)

● The pressure sampling pipe is blocked or leaking, and the pressure decays too fast. The sampling pipeline needs to be overhauled.

● The actual production consumption is unstable, sometimes large and sometimes small or discontinuous. The air storage tank can be added after the compressor unit.

● When the compressor unit is unloaded, the minimum pressure valve is not closed in time or tightly. Repair the minimum pressure valve and replace it if necessary.

● Loading control solenoid valve failure. Should check the solenoid valve, may be affected by the oil and water gas caused by the action is not sensitive or the coil burned out. Check and replace if necessary.

● The pressure sensor that controls the start and stop of the unit is faulty or damaged. Maintenance and replacement shall be carried out.

5. The compressor unit will not be unloaded after loading

● The actual air consumption of the production is greater than the air output of the compressor unit, and the compressor unit is always in the loading operation state.

● Check whether there is air leakage in the connected pipe network.

● Check whether the loading and unloading solenoid valve operates or is damaged.

● Check whether the intake valve of the compressor unit is closed tightly..

● Check the drain valve of the gas-water separator for leakage.

Check whether the safety valve and oil separator have internal leakage.

6. Excessive fuel consumption or discharged compressed air contains oil

● Too much fuel. If the oil level is too high, the air flow will draw the oil in the oil separator into the compressed air. The oil content in the discharged compressed air exceeds the standard. Therefore, the refueling quantity should be controlled under the yellow line on the red line.

● The failure of the minimum pressure spring causes the opening pressure to be too low, the pressure difference between the front and rear of the oil separator is too large, the flow rate of the oil and gas mixture in the tank is high, and the condensed oil on the cylinder wall and the oil separation filter element will be taken away by the high-speed airflow, thus affecting the oil and gas separation effect.

● The filter element of the oil separator is blocked or damaged, check and clean, and replace it if necessary.

● Oil separator oil return pipe is blocked, check and clean.

● If there is leakage in the air cooler system, check and repair it and repair it.

● Oil use time is overdue and oil quality is deteriorated. Clean the compressor unit and replace the qualified oil.

7. The output compressed air contains heavy moisture

● The water separator/condensate drain valve is damaged. Carefully check and clean, if both are damaged, replace them.

● Condensate drain valve or its piping is blocked. Check and clean.

● Improper installation of condensate drain pipe or drain valve, the drain pipe should be inclined downward from the drain end, and the condensate drain valve should be reinstalled.

8,

● Compressor unit failure, bearing damage or main engine head rotor failure. Should immediately stop contact with the dealer or after-sales service center.

● The cover panel is not installed properly, and the sound insulation cotton is damaged.

● If the parts are loose, carefully check and strengthen the connecting parts.

9. Large vibration of compressor unit

● If the parts are loose, carefully check and strengthen the connecting parts.

● If the motor or host bearing is damaged, stop immediately and contact the dealer or after-sales service center.

● The foundation of the compressor unit is loose or there are other equipment in the area that resonates with the unit.

The cooling and lubrication system, oil and gas separation system and air volume regulation system of screw air compressor are the key systems to ensure the normal operation of the unit. The failure probability of these systems is about 80% of the total failure rate of the whole compressor unit. The failure of compressor unit is mostly related to "two devices" (oil separator, air cooler) and "three cores" (air filter element, oil separator filter element, oil filter element), "four valves" (intake poppet valve, minimum pressure valve, oil cut-off valve, temperature control valve).

To ensure the normal operation of the compressor unit, the daily maintenance of these components should be done, the "two devices" should be cleaned regularly, the "three cores" should be replaced in strict accordance with the established maintenance plan, and appropriate amount of valve spare parts should be reserved. As long as we strictly abide by the safety operation procedures of the compressor unit, do maintenance on time, replace relevant accessories in a timely manner, increase the adjustment and control of parameters such as ambient temperature and pressure of the compressor unit, and be familiar with the handling methods of various common faults, the compressor unit can be guaranteed to operate under better working conditions and provide a strong guarantee for production.