| Case Name |
Leakage and fire caused due to an abnormal reaction from contamination of a heat medium to raw materials in a heat exchanger type reactor having a corroded part at an acrolein manufacturing plant |
| Pictograph |
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| Date |
December 23, 1998 |
| Place |
Niihama, Ehime, Japan |
| Location |
Chemical factory |
| Overview |
There was a forest fire following trouble at a methionine and acrolein synthesis plant. The flow rate of nitrate coolant at the shell side fluid in a heat exchanger-type reactor was decreased to less than half of the design value. The flow of nitrate coolant became uneven and a high-temperature part was formed. Therefore, a steel heat exchanger tube at the central part of the heat exchanger corroded, and a hole opened. Nitrate and acrolein started an incompatible reaction. As high-temperature material blew off from a rupture disk, a forest fire occurred. In addition, although it is a coolant, it is assumed that the temperature of the nitrate exceeded 500 °C. |
| Incident |
An abnormal reaction occurred at a heat exchanger-type synthetic reactor for methionine and acrolein. A rupture disk operated, and hot materials from the rupture disk caused a fire in a neighboring forest.
During routine operation, a hole was made at a heat exchanger tube, and coolant (hot nitrate coolant) leaked inside. Nitrate and acrolein made contact and an abnormal reaction occurred. Then the rupture disk operated. |
| Processing |
Manufacture |
| Individual Process |
Reaction |
| Chemical Reaction |
Oxidation |
| Chemical Equation |
Fig2.Chemical reaction formula
|
| Substance |
Acrolein, Fig3 |
| Nitrate |
| Type of Accident |
Leakage, fire |
| Sequence |
February, 1998. To make visual inspection of coolant easy, the flow rate of the coolant was reduced from 100% to 55%.
00:19 on December 23rd. A hole was made at a reaction tube in a reactor, and the inlet pressure of the reactor dropped.
00:22. Smoke came out from a tank of brine nitrate.
00:26. A high-temperature alarm operated due to a high temperature of the reactor tube, and an interlock operated.
00:27. A rupture disk of the reactor operated, and some contents blew off.
00:29. The reactor exploded and a fire occurred in the factory. High-temperature material blew off from the vent piping and a forest fire occurred.
00:35. Six self defense fire engines and 30 fire fighters turned out. Initial fire extinguishing was done with fire fighting equipment. The forest fire was confirmed.
00:43 The public fire department was notified. 26 fire engines and 126 fire fighters turned out and sprayed water on the structure.
01:50. The fire in the factory was confirmed to have been extinguished.
04:20. The forest fire was extinguished. |
| Cause |
The flow rate of coolant that flows at the shell side of the heat exchanger-type reactor was reduced to about half of the design value. Therefore, a temperature deviation was formed in the reactor. Corrosion progressed in the central part where the coolant was at a high temperature. Coolant leaked from the part damaged by corrosion. The hot nitrate coolant and acrolein made contact and an abnormal reaction occurred. |
| Response |
Initial fire extinguishing was carried out with firefighting equipment.
The structure was sprayed with water.
Water was sprayed on lower grass, dry grass, and fallen trees. |
| Countermeasures |
Safety measures for the process are taken.
Increasing measuring points for temperature in the reactor.
Miscellaneous trees around the plant were cut down to prevent a forest fire.
The safety operation manual is reeducated.
The management system should be strengthened. |
| Knowledge Comment |
Corrosion is promoted in a severe temperature environment.
When the treated amount increases, a heat exchanger is well studied on its capability, vibration, etc.
Also when the treated amount decreases, as there is excess capability and an uneven flow caused by excessive decrease in the flow rate, etc., a prudent study is required.
Discharging devices, such as a rupture disk and a safety valve, are required to lead materials to a safe place. |
| Background |
As the flow rate at the shell side of the heat exchanger was decreased excessively, the flow became unequal. Therefore, an unexpected hot part was formed, and corrosion advanced. Although it might have been unknown at the time, the operating conditions should have been changed after considering carefully the corrosion tendency of nitrate used as coolant. It was not predicted by a study of the company. Nitrate corrosion is accelerated greatly at over 500 °C, and the corrosion rate exceeds 2 mm/year. The heat exchanger tube was very thin, so sufficient caution in corrosion was required |
| Sequel |
As the forest was on a steep slope and there was no mountain path, fire-fighting was difficult. |
| Incidental Discussion |
On increasing the treated amount, careful study is required. However, on decreasing the treated amount, it tends to be neglected. It is not always true that "the greater services for the lesser" about some equipment. |
| Reason for Adding to DB |
Example of fire caused due to corrosion from an uneven flow at a low flow rate in a heat exchanger |
| Scenario |
| Primary Scenario
|
Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Insufficient Analysis or Research, Insufficient Prior Research, Corrosion/Flow, Ignorance, Insufficient Knowledge, Insufficient Study, Oxidation Reaction, Planning and Design, Poor Planning, Poor Operation Planning, Non-Regular Action, Change, Flow Rate Change, Bad Event, Thermo-Fluid Event, Temperature Rising, Failure, Abrasion, Corrosion, Secondary Damage, External Damage, Fire, Loss to Organization, Economic Loss, Manetary Damage 160 million yen
|
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| Sources |
Fire and Disaster Management Agency, Methionine, acrolein process plant fire. Accident cases of dangerous materials. 1998, pp.418-420.
High Pressure Gas Safety Inst. of Japan, High-pressure gas protection overview. 1999 edition, p.149 (2000).
The Res. Inst. of Industrial Safety material. (closed)
|
| Physical Damage |
About 36 square meters of the second floor of acrolein plant was damaged by fire. |
| Financial Cost |
¥ 160 million. (Fire and Disaster Managing Agency) . |
| Consequences |
An adjacent forest of about 1000 square meters was damaged by fire. |
| Multimedia Files |
Fig3.Chemical formula
|
| Field |
Chemicals and Plants
|
| Author |
ITAGAKI, Haruhiko (Japan National Institute of Occupational Safety and Health)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
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