A.5.1 Brief description of equipment
A power plant's pneumatic ash conveying system has a total of 4 screw air compressors installed as the air supply source. The air compressor specifications are 110kW, water-cooled unit, exhaust volume is 20m³/min, and the motor speed is 1480r/min.
A.5.2 Fault phenomenon
A power plant's pneumatic ash conveying system has a total of 4 screw air compressors installed as air supply sources. During normal operation, 3 air compressors are in operation and 1 is in standby mode. The standby air compressor is switched regularly every month. The operator on duty switched the #3 air compressor from standby mode to operation mode. After running for less than 2 minutes, a muffled sound was heard and the operation sound of the #3 air compressor suddenly changed. The operator checked and found that the oil level in the oil mirror of the air compressor oil and gas barrel was not visible. The #3 air compressor was immediately stopped and the outlet door was closed. After the air compressor system was depressurized, the oil level was still not visible. The maintenance personnel were notified to check and suspected that the oil fine separator was damaged, resulting in the extraction of lubricating oil. The maintenance personnel applied for a work ticket to check the air compressor and found that the oil fine separator had been severely deformed and cracked, and a small amount of lubricating oil remained at the bottom of the oil and gas barrel.
A.5.3 Cause Analysis
How long is the standby air compressor suitable for shutdown? Different climatic conditions in different places can make different choices; In this factory, there has been an air compressor standby shutdown for one month. When it was restarted, the oil fine separator blocked alarm appeared, indicating that the air compressor in this factory is not suitable for shutdown for one month, but it did not attract the attention of the operation department; #3 air compressor was only 2000 hours away from the last maintenance. Due to the long shutdown, the oil dirt and ash adhered to the oil fine separator dried, causing the flow area of the oil fine separator to decrease. After the air compressor was started, the separator adhered to new oil, and the flow area was further reduced. Then it was squeezed, deformed and ruptured by the huge pressure difference before and after the separator, resulting in the lubricating oil being pumped away.
A.5.4 Preventive measures
Adjust the standby time of the air compressor and switch the air compressor once every 15 days.
