In the petrochemical industry, the oil injected screw air compressor has been widely used because of its reliable operation, high efficiency, long service life, gas flow not affected by exhaust pressure, stable operation without surge and other advantages. Especially, as an advanced aerodynamic equipment in the public system, it is widely used in the air compressor station to provide instrument air for the device. Therefore, the safe operation of the air compressor unit ensures the stability of the instrument air of the device and the safe operation of the device. During the daily operation of oil injection screw air compressor, due to inadequate maintenance, the unit often has high exhaust temperature alarm and unit interlock shutdown failures. Therefore, it is very important to analyze the faults of high exhaust temperature alarm of screw air compressor and unit interlock shutdown in detail, and propose effective treatment methods to ensure the normal and stable operation of screw air compressor.
(1) Event Description
On May 15, 2016, the air compressor unit J-6001A, which is in production and operation, suddenly shut down in a chain way. It was found that the PLC display screen showed an alarm of high exhaust temperature, an alarm of high differential pressure of oil gas separator, and an alarm of high differential pressure of oil filter. In order to ensure the safe operation of the unit production, replace the standby unit J-6001B, and shut down the faulty unit J-6001A for maintenance.
(2) Introduction to maintenance
At 8:30 on May 16, 2016, the faulty unit J-6001A was overhauled. In view of the interlock shutdown failure of high exhaust temperature alarm, high differential pressure alarm of oil gas separator, and high differential pressure alarm of oil filter, the main overhaul content was to repair and maintain the oil circuit system and circulating water cooling system of the unit. From the maintenance, there are mainly the following problems:
1) The filter element of oil-gas separator is scaling and blocked;
2) The oil filter is blocked;
3) The oil cut-off valve is out of order and the valve core is stuck;
4) The temperature control valve is stuck due to failure;
5) The oil cooler is severely encrusted and blocked.