توضیحات :
BEACON SAFETY MASSAGE
ایمنی فرآیند
نوامبر ۲۰۱۸
Accumulation of small changes leads to an explosion
In September 2012, at an industrial site in Himeji, Japan, a 70 cu m (18,500 US gal) fixed roof acrylic acid (AA) tank exploded, and a fire followed. There was one fatality, a fire-fighter. 36 people were injured – ۲ policemen, 24 firefighters, and 10 plant workers. The tank was destroyed and nearby facilities were significantly damaged (Photo 1). There were no major impacts to the neighborhood and environment.
The tank provided intermediate storage between two distillation columns for purifying AA. Originally the tank had been used at full capacity. The contents were cooled and mixed by pumping from the bottom of the tank to the top. Later, the normal operating level was reduced to a level below the cooling coil. The contents were no longer recirculated to the top of the tank, but instead to a nozzle near the bottom that was also used to connect a level gauge (Drawing 2).
At the time of explosion, the plant was conducting a test of the downstream distillation column, which required stopping feed from this tank. The level of the tank gradually increased to its original operating level. Without recycle to the top of the tank, the AA above the cooling coils was not mixed and cooled. The temperature of the incoming AA was believed to be below the onset temperature for polymerization, and the AA contained polymerization inhibitor. However, the temperature in the tank increased, especially at the top. The tank eventually over pressurized and exploded.
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