Diagnosis of abnormal temperature of rig air compressor

An air compressor with a 3650h Finnish Tomlock company cha660 open-air rig has an abnormal temperature. There was a sudden rise in the temperature of the air compressor oil during the operation.

"Fault Analysis and Troubleshooting"

At that time, the ambient temperature was 5-11 °C, and the machine temperature increased rapidly in the morning and evening. When drilled to a depth of 3m with a drill with a diameter of 89mm, the oil temperature will quickly rise from 40°C to 75-105°C. If the operation continues, the oil temperature alarm indicator will flash and the engine will automatically turn off. However, sometimes the rig air compressor temperature can work continuously at (75-90 ° C). The air compressor is an oil-cooled, asymmetric rotor, and spiral air compressor. Occasionally, the air compressor can work normally. Therefore, the oil filter 12 is inspected first. As a result, no metal foreign matter is found, thereby eliminating the internal bearing of the air compressor and The possibility of abnormal wear of the rotor. Then check the cooling fan and the radiator are blocked, and the results are normal. The cooling and circulation of the air compressor oil is maintained by the pressure difference between the oil separator and the air inlet of the air compressor, if the internal pressure of the oil separator is lower than 0.3 mpa (this pressure is guaranteed by the minimum pressure control valve 8) ), will make the oil circulation is not smooth, reduce the heat dissipation effect, there will also be high temperature phenomenon of the oil. After eliminating the above reasons, the fault point is concentrated on the temperature control switch 10.

The working condition of the air compressor temperature control switch of the drilling rig is: when the oil temperature is lower than 45 °C, the oil does not pass through the radiator, the oil pressure overcomes the elastic force of the bimetal spring, opens the check valve, and flows back to the air compressor for lubrication. And cooling. When the oil temperature is between 45-48 ° C, the thrust generated by the expansion of the bimetallic spring begins to close the check valve, so that a part of the oil is cooled by the radiator; when the oil temperature exceeds 48 ° C, the check valve is closed, the oil All are cooled by the radiator. In order to accurately determine whether the temperature control switch is out of balance, an inductor thermometer can be used to measure the temperature difference at the inlet and outlet of the radiator. According to the actual measurement, the temperature of the tube wall on the inlet side of the radiator is 78 °C, and the outlet side is only 23 °C. The temperature difference between the inlet and outlet is large, indicating that the temperature control switch is not completely shut off when the oil temperature exceeds 48 °C, thereby determining the temperature control. The switch is in an active state.

The temperature control switch was disassembled and found that the appearance of the bimetal spring was normal, and the guiding portion of the check valve had obvious eccentric wear and stagnation. Due to limited field conditions, it was decided to add a 2mm thick adjustment gasket with a hole in the back of the bimetal spring for temporary treatment. The installation test shows that the temperature of the rig air compressor can be restored at normal temperature.

According to the requirements of regular maintenance of the open rig, check the temperature control switch of the air compressor every 600h. To this end, we dismantled the temperature control switch of another rig and found that the deviation of the eccentricity of the guide part of the check valve is also very obvious. Therefore, in order to completely restore the adjustment function of the temperature control switch, it is necessary to solve the problem of the partial wear of the check valve of the check valve.

After careful measurement, the matching gap between the guide part size a of the check valve and the hole in the valve body is 0.20 mm. Due to the large gap, the guiding effect is reduced, which makes the one-way valve eccentrically severe, eventually leading to the opening of the check valve at low temperature start. The stuck state occurs in the state, and the additional thrust generated by the expansion of the temperature-controlled spring after the temperature rises is not enough to return the check valve to the closed position, which is the root cause of the excessive oil temperature. A one-way valve spool was reworked, and the matching clearance of the guiding portion was adjusted to 0.03-0.05mm. The installation test showed that the check valve did not appear stuck, and the air compressor worked normally.