Technical analysis on explosion accident of the re

2022-08-07
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Technical analysis on the explosion accident of rubber auxiliary reactor at about 22:00 on April 22, 2002, a reactor explosion accident occurred in a chemical enterprise in Yuanping City, Shanxi Province, resulting in one death, one serious injury and one minor injury. The explosion shock wave lifted almost all the prefabricated slab roofs of the workshop of about 200m2, all the windows of the south wall were broken, the broken slag flew out about 50m, all the 40 M20 bolts on the upper head of the reactor were broken (detached), the head flew up about ten meters to the roof, bounced back to the ground, the kettle body was located on the first floor from the second floor platform, the lifted prefabricated slab fell on the workshop floor, and the south wall of the workshop was bulging

I. situation before the accident

the enterprise is a private joint-stock enterprise whose product potential has been continuously explored. Three years ago, it bought the production technology of rubber additives from a university. In the first two years, due to market reasons, the production has been in a state of on-off and on-off. However, since the end of last year, the product has gradually expanded its market share with the advantages of low cost and high quality. Therefore, the enterprise decided to transform the original production device technology. The renovation of the new equipment was completed on April 10, 2002, and the production began on April 11, 2002, with three shifts a day. The process flow includes reaction, crystallization, centrifugal separation, vacuum dehydration and packaging. The process is intermittent production, with 2 workers per shift. At 16:00 on April 13, after two operators took over the shift to avoid electricity, they added materials to the reaction kettle according to the operation requirements, then stirred, oxygenated, reacted and kept warm, and then pressed the materials to the crystallization kettle at about 21:00. At this time, the pellet pressure tester includes an automatic feeding device. The pressure of the reaction kettle is 0.2MPa (gauge pressure), and the temperature of the feed liquid is below 40 ℃. During the pressing process, the operator found that the material did not flow into the crystallization kettle, but leaked from the flange under the feeding valve on the first floor. The main operator tried to stop the leakage, but still could not stop the material leakage. He was busy collecting the material in pots, recycling several pots of material, and pouring it into the nearby centrifuge. In the process of dealing with the leakage, the owner hopes to help you in the future product purchase. The operator sent another worker to the duty room to call the technical director of the factory to deal with the fault. At about 22:00, the technical director came to the site and first went to the leakage on the first floor to collect materials and pour them into the centrifuge. Another worker walked to the door of the workshop because of the smell of the leakage. At this time, the reactor suddenly exploded, causing an accident

II. Accident site conditions

the feeding valve of the reaction kettle is open, the oxygen valve is closed, the feeding pipe (40mm) is disconnected along the weld, about three-quarters of the pipe section of the feeding pipe is blocked by crystals from the crack, only two opposite bolts are screwed on the flange below the feeding valve, there is no carbon deposit in the reaction kettle and its connected pipes, but the filter cloth in the centrifuge is burned. According to the workers with minor injuries, there is no fire before the accident, The main operator was seriously injured and could not explain the situation before the accident

III. materials in the reaction process

the main raw materials used in the product are carbon disulfide, diethylamine, isopropanol, oxygen and catalyst. The first three materials are flammable liquids, and their boiling points and explosion ranges are shown in Table 1. In order to ensure the full reaction of diethylamine in the reaction process, carbon disulfide and oxygen should be appropriately excessive to ensure a high reaction conversion rate. The material in the reactor is about 450L. After the reaction, the pressure in the kettle is 0.2MPa (gauge pressure) and the temperature is below 40 ℃. The liquid is a mixture of m-isopropyl alcohol, rubber additive, carbon disulfide and a small amount of diethylamine. The gas is a mixture of carbon disulfide, isopropanol, oxygen and a small amount of diethylamine in saturated state at this temperature and pressure

table 1

flammability

material carbon disulfide diethylamine isopropanol

boiling point (℃) 46.3 55 5 82.. 4

explosion range (volume ratio) 0.8%-52.8% 1.7%-10.1% 3.8%-10.2%

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