Analysis of fire accidents caused by leaks in catalytic devices

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Fire accident caused by leakage in the catalytic unit. I. Incident overview: On ** day of ** month, ** year, after taking over shifts at the catalytic unit, the night shift crew began to conduct continuous inspections of the production site around the clock. At around 0:51, the operator responsible for monitoring the reaction process went to the location of the passivation agent pump and noticed smoke coming from the heat exchange area. He immediately went to investigate and saw red light under E2215, which indicated a fire. He reported the situation urgently and brought steam-based fire extinguishing equipment to the scene. Subsequently, the team leader rushed to the site along with other crew members. The workshop duty personnel arrived at the scene upon receiving the notification to participate in the emergency response. On one hand, measures such as using dry powder fire extinguishers and steam were taken to put out the fire; on the other hand, it was determined that the source of the leak and fire was at the heat circuit control valve for the slurry. In accordance with the emergency response plan, the valves upstream and downstream of this control valve were immediately closed. During the process of closing the valve, there was a loud explosion; the fire on the ground intensified, and the amount of leakage increased, prompting people to immediately evacuate the dangerous area. Due to the intense fire, an emergency shutdown was initiated; the personnel in the control room called the fire department at 119 and informed the production supervisor. The fire alarm was reported promptly, and once the fire brigade arrived, they quickly got to work putting out the fire. The company’s on-site leadership rushed to the scene to direct the firefighting efforts, and staff from various departments promptly joined in the effort to put out the fire. At around 1:30, the fire began to shrink, and the fire department seized the opportunity to launch a fierce attack to put out the flames; by 1:52, all remaining embers were extinguished. During this period, the relevant leaders and staff promptly took measures such as blocking external drainage ditches to prevent environmental pollution incidents. Upon inspection of the scene, 2 control valves were damaged by the fire, some signal wires were damaged as well, and 3 valves were affected by the flames; the direct economic loss amounted to approximately 35,000 yuan. There were no casualties, and no environmental pollution incidents occurred. II. Analysis of the accident causes 1. Upon inspecting the scene after the fire, the oil slurry heat path control valve was severely damaged; this control valve had been destroyed, and the gasket at its front end was protruding. Upon disassembling and inspecting the thermal control valve assembly of the slurry, it was found that the control valve spool had worn out, and the flange upstream of the control valve was severely eroded; in two areas, the erosion had reached beyond the edge of the sealing surface. This year, the solid content of the slurry in the catalytic unit remained high for an extended period (16.3 to >25.4 g/L). Additionally, the increased line speed of the slurry in the reduction section at control valve TV-1101A caused wear on the sealing surfaces, leading to leaks and protrusion of the sealing gaskets, which further increased the leakage volume. The heat generated by the leaking slurry could not be dissipated in time; as a result, the slurry at around 310°C caught fire spontaneously (the auto-ignition temperature of this slurry is 230°C). This was the direct and primary cause of the leak and fire incident. 2. The solid content in the slurry system remains high, which constitutes a risk to safe operation. Although plans for supervised operation and emergency response protocols have been established, these measures fail to address the issue of high solid content in the slurry. As a result, the slurry system operates under high risks; in areas such as pipe bends, flow meters, and sections with changes in diameter, where the flow velocity and direction of the slurry change significantly, erosion is severe, increasing the likelihood of leaks. Recently, the slurry system has experienced multiple instances of wear and tear. These were detected in a timely manner through routine inspections, and prompt action was taken to prevent the situation from worsening, which indicates that the risk of fire accidents is increasing. In production operation management, insufficient awareness of accident risks and inadequate control measures for key risk areas are indirect but important causes of accidents.