| Case Name |
Fire of powder resin due to increased powder by remodeling to improve efficiency at an ABS resin manufacturing plant |
| Pictograph |
|
| Date |
June 30, 1984 |
| Location |
Chemical factory |
| Overview |
Black smoke rose from the drying room and the bucket elevator on drying ABS resin. There was an increased quantity of powder generated after the drier was remodeled two months before, and powder concentration increased due to the replacement of generated powder to the bucket elevator inlet. Nevertheless, no measure had been taken. As powder is potentially explosive, the facilities should be modified to reduce powder generation. |
| Incident |
As ABS resin is wet powder after reaction, it has to be dried to reduce its moisture to below 1% before being pelletized by an extruder. The dryer was exchanged to another model for energy saving. About two months after, black smoke rose during usual operation from the drying room and the bucket elevator. |
| Processing |
Manufacture |
| Individual Process |
Drying and desiccation |
| Process Flow |
Fig2.Unit process flow
|
| Substance |
ABS resin |
| Type of Accident |
Fire |
| Sequence |
In April, 1984. The drier was changed to a squeezing dehydrator. The amount of resin powder increased as a result. The powder was returned to a bucket elevator.
19:15 on June 30th. Fire alarm sounded during operation. Black smoke rose from the drying room and the conveyor.
20:30. Fire was extinguished by spraying water. |
| Cause |
With static electricity generated in the bucket elevator for carrying dried and dehydrated ABS resin to the extruder, the ABS resin powder was ignited. |
| Response |
Extinguished by water |
| Countermeasures |
1 The dehydration molding machine was changed to one that generated less powder.
2. Instead of the bucket elevator, a gas conveying system with nitrogen was installed.
3. Remote operation system was introduced to do emergency shutdown and fire fighting quickly in case of similar accidents. |
| Knowledge Comment |
The powder involves unique and dangerous characteristics. Measures to avoid dangers have to be considered taking these characteristics into account. |
| Background |
A squeezing dehydrator replaced the old drier to save energy. Consequently, the amount of powder generated increased. In addition, the concentration of powder increased due to the replacement of powder to the bucket elevator inlet. Although the danger of dust explosion and powder combustion increased, static electricity that could be an ignition source was not properly controlled. Despite the increase of powder, no measure was taken to control it. There seemed to be indifference to the danger of powder. |
| Incidental Discussion |
In abnormal circumstances, it is not always wise to restart operation immediately after emergency measures are completed. This is especially true when no one understand what exactly happened. |
| Reason for Adding to DB |
Example of accident caused due to no care of worse function by remodeling |
| Scenario |
| Primary Scenario
|
Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Insufficient Analysis or Research, Insufficient Prior Research, Insuficient List-up of Impropers, Planning and Design, Poor Planning, Unbalanced Design, Non-Regular Action, Inaction, Neglect of Inproper Results, Bad Event, Mechanical Event, Increase of Dust Generation, Secondary Damage, External Damage, Fire
|
|
| Sources |
High Pressure Gas Safety Inst. of Japan. ABS resin manufacturing plant. Ignition of the powder resin by static electricity spark. Accident examples of Petroleum refinery and Petrochemical unit. pp.154-155(1995)
|
| Field |
Chemicals and Plants
|
| Author |
WAKAKURA, Masahide (Kanagawa Industrial Technology Research Institute)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
|
