| Case Name |
Explosion and fire caused due to a change from sodium salt to potassium salt at a di-cumyl hydroperoxide manufacturing plant |
| Pictograph |
|
| Date |
June 13, 1988 |
| Place |
Taketoyo, Aichi, Japan |
| Location |
Chemical factory |
| Overview |
A blockage in the flow meter occurred at the dicumylperoxide (DCP) manufacturing plant a week before. It exploded when temporary measures were taken without investigating the true cause. The reaction auxiliaries were changed from NaOH to KOH, and the explosion occurred during this process change. If an evaluation of reaction hazards had been carried out, the accident might have been prevented. |
| Incident |
At a dicumylperoxide (DCP) manufacturing plant with using cumene hydroperoxide (CHP) and α-cumyl alcohol (α-CA) as raw materials, an alarm at a flow meter that showed a circulation flow rate sounded. Then the heat exchanger exploded, the contents spouted out from piping, etc. and ignited. |
| Processing |
Manufacture |
| Individual Process |
Reaction |
| Process Flow |
Fig2.Process flow
|
|
Fig3.Unit process flow
|
| Chemical Reaction |
Condensation |
| Chemical Equation |
Fig4.Chemical reaction formula
|
| Substance |
di-alpha-cumyl peroxide, Fig5 |
| Type of Accident |
Explosion, fire |
| Sequence |
At a DCP manufacturing plant, a stabilizer for a raw material of CHP was changed from sodium hydroxide to potassium hydroxide, and a reaction catalyst of α-CA was also changed to potassium hydroxide about one month before the accident.
The flow meter of a circulation pipeline between the ripening drum and external heat exchanger showed an abnormal flow rate which seemed to be due to a blockage for a week before the accident.
On the day of the accident, the DCP manufacturing plant operated as usual. An alarm indicating an abnormality in the flow meter of the circulation pipeline of the external heat exchanger and ripening drum sounded in the control room. Therefore, an operator went to the site. Immediately, the heat exchanger exploded, and the contents that spouted out from piping, etc. ignited. The operator received burns and about 100 square meters of the plant, including drums, pumps, and instruments were destroyed by the fire. |
| Cause |
Potassium hydroxide was used as a stabilizer for a raw material of CHP and as a reaction catalyst for another raw material of α-CA. It was changed from sodium hydroxide about a month before to obtain a higher quality product. In the DCP reaction process, since perchloric acid (HClO4) is used as a catalyst, a neutralization reaction with potassium hydroxide was caused, generated potassium perchlorate (KClO4), which was difficult to dissolve in water. More potassium perchlorate deposited in the non-aqueous ripening drum than in the reaction vessel, and stuck to the wall surface of the heat exchanger. Potassium perchlorate also formed a complex with perchloric acid, and the perchloric acid was concentrated. Through the mixing of potassium perchlorate, concentrated perchloric acid, and an intermediate product of DCP, etc., an explosive mixture was generated, and it decomposed exothermally at a low temperature (42 °C), causing the accident. |
| Countermeasures |
It is necessary to confirm the safety of a secondary reaction product in the development of new products. Even though the abnormality of the flow meter mounted at the outlet of the heat exchanger was detected a week before, a fundamental countermeasure with an investigation of the cause of the blockage was not taken. As an emergency countermeasure, open and close operation of the flow control valve and changing of the solution sending pump were executed, and the explosion occurred during the operation. From this fact it can be understood that an investigation of the fundamental cause of the trouble is necessary.
The catalyst should be changed to sodium hydroxide, with making the process in which potassium hydroxide does not mix with raw materials.
Inspections were established, and an overhaul of the heat exchanger was facilitated.
The cleaning line, by which hot-water cleaning could be simplified to clean the heat exchanger inside, was installed for the prevention of a blockage.
The recorder and alarm for heat exchanger outlet temperature were installed. |
| Knowledge Comment |
1. Potassium and sodium as alkali metals and calcium and magnesium as alkaline earth metals have relatively similar chemical characteristics. However, it does not mean their products have similar solubility or a reaction rate. They are not always interchangeable.
2. Reaction chemicals must not be changed simply because they are not main components of a reaction. It is necessary to sufficiently examine reaction hazards. |
| Background |
Sufficient evaluation of a mixing hazard was not carried on the changing the raw materials. This was a problem of change management. |
| Reason for Adding to DB |
Example of explosion caused due to a lack of basic knowledge on reaction hazards |
| Scenario |
| Primary Scenario
|
Insufficient Analysis or Research, Insufficient Practice, Inadequate Imagination, Ignorance, Insufficient Knowledge, Insufficient Study, Poor Value Perception, Poor Safety Awareness, Insufficient Recognition of Risk, Condensation Reaction, Planning and Design, Poor Planning, Poor Planning of Changing Raw Material, Regular Operation, Erroneous Operation, No Countermeasure against Abnormality, Bad Event, Chemical Phenomenon, Abnormal Reaction, Secondary Damage, External Damage, Explosion/Fire, Bodily Harm, Injury, 1 person injured, Loss to Organization, Economic Loss, Plant Burnt up
|
|
| Sources |
National dangerous material safety association, Explosion in ripening drum heat exchanger that manufactures dicumylperoxide. 100 cases of accidents in dangerous facilities. pp.20-22(1991)
Tamura Masamitsu, Wakakura Masahide, Explosion and fire of cumene hydroperoxide, Reaction danger,-accident case and analysis-p.65(1995)
|
| Number of Injuries |
1 |
| Physical Damage |
A heat exchanger was damaged. |
| Multimedia Files |
Fig5.Chemical formula
|
| Notes |
Solubility: NaClO4 70.9g/100g H2O, KClO4 3.6kg/100g H2O |
| Field |
Chemicals and Plants
|
| Author |
ARAI, Mitsuru (Environmental Science Center, The University of Tokyo)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
|
|
