Sealing oil leakage in the reformation cycle machine; molecular sieve deactivation

Thread Content

Event name: Leakage of seal oil in the reforming cycle machine, deactivation of the molecular sieve. Time of occurrence: 4 p.m. on March 30, 1997. Event details: On March 25, 1997, the reforming unit began to shut down in preparation for a major overhaul. Molecular sieve drying started at 5 p.m. on March 28, and it was completed at 2 p.m. on March 29; thereafter it was integrated into the reforming catalyst regeneration system. The reforming catalyst begins to heat up and coking. At 4:00 on the 30th, the personnel on duty noticed a decrease in the lubricating oil level of the reforming cycle machine K-3201; the cycle machine had to be stopped at 21:00, resulting in an interruption in catalyst regeneration. Due to the late discovery and insufficient awareness of the problems that oil leakage from the lubricant could cause, the entire molecular sieve became saturated with lubricant. On March 31, a blasting and purging operation was carried out on the pipeline from K-3201 to E-3201 inlet, and on April 1, the unit was restarted for catalyst regeneration. Analysis showed that the reforming and reverse catalysts were also deactivated due to shock, and had to be replaced entirely; the molecular sieves were also replaced all, resulting in significant losses. Cause analysis: 1. The seal of the reforming cycle machine was inadequate, and oil leakage from the seal oil was the main cause of this accident. 2. The personnel on duty failed to detect in a timely manner the drop in the level of the seal oil in the tank due to oil leakage, and had an insufficient understanding of the hazards associated with this. 3. The circulation machine has been experiencing slight leakage of seal oil, especially when there are significant changes in the operating conditions at the start of regeneration; under such conditions, the seal oil leaks more easily. The absence of a liquid separation tank at the outlet of the circulation machine, along with a lack of preventive measures, was also one of the causes of this incident. Precautionary measures: 1. Separate liquid separation tanks were added to the first and second stages at the outlet of the circulation unit to prevent liquid from causing damage to the molecular sieve and catalyst; these were put into use in May 1997. 2. When the operating conditions of the circulation machine change, especially when transitioning from normal production to the regeneration phase, special attention should be paid to the condition of the sealing oil as well as to any changes in the oil tank level. 3. Personnel on duty should conduct thorough inspections, enhance their safety awareness, and pay attention to protecting the catalyst.