| Case Name |
Fire and explosion of hydrogen occurred due to excessive supply of waste liquid at a neutralization processing unit |
| Pictograph |
|
| Date |
September 12, 1989 |
| Place |
Sumida, Tokyo, Japan |
| Location |
Metal products factory |
| Overview |
An explosion and fire occurred at a waste treatment unit of an aluminum container-manufacturing plant. Strong acidic aluminum waste liquid was processed in a pH adjust vessel and then, sent to a waste liquid pit. The amount of waste liquid was beyond the capacity of the pH adjust vessel. Therefore, a large amount of hydrogen was generated in the pit, and it caused a fire and an explosion. |
| Incident |
An explosion occurred at a waste treating unit in a plant where aluminum cosmetic containers were manufactured. Strong acidic aluminum waste liquid containing sulfuric acid and aluminum powder was generated in the aluminum oxide(Al2O3) processing device, went through the pH adjust vessel and flowed into the waste liquid pit. Then, an explosion occurred in the pit. Reaction formula of neutralization is shown in Fig3. |
| Processing |
Manufacture |
| Individual Process |
Waste water and waste oil treatment |
| Process Flow |
Fig2.Unit process flow
|
| Chemical Equation |
Fig3.Chemical reaction formula
|
| Substance |
Sulfuric acid, Fig4 |
| Aluminum, Fig5 |
| Type of Accident |
Explosion, fire |
| Sequence |
Strong acidic aluminum waste liquid containing sulfuric acid and aluminum powder was supplied to neutralization processing.
The liquid from the neutralization vessel flowed into the next waste liquid pit.
An explosion occurred suddenly in the waste liquid pit. |
| Cause |
The waste liquid flow rate was above the capacity of the pH adjust vessel, because too much waste fluid flowed. Then, the fluid flowed into the next tank before neutralization was completed. Therefore, a large amount of hydrogen was generated from the reaction of aluminum and sulfuric acid; it leaked from a hole in the waste liquid pit, was ignited by sparks from the time recorder, and caused a fire and an explosion. |
| Response |
Fire extinguishing activities |
| Countermeasures |
The amount of acidic aluminum processed should be limited.
Ventilation facilities for combustible gas should be installed. |
| Knowledge Comment |
Persons related to operation of a chemical plant should have an awareness that operation beyond the capacity of the plant is not safe. So they should give consideration to a device to avoid excessive flows, and install ventilation systems for combustible gas. |
| Background |
The principal cause might have been that a person related did not fully understand the basic performance of the pH adjust vessel, such as; 1) limited capacity of the pH adjust vessel, 2) there is always a possibility that acidic waste liquid can generate a combustible gas such as hydrogen in a waste liquid pit. |
| Incidental Discussion |
There are often hazards from chemical reactions even at a plant that does not seem to be related to chemistry. The problem is how to give education to workers on hazards. When they try to produce more, they carefully investigate production facilities, but waste water treatment is sometimes ignored. Paying attention to auxiliary facilities like this is one of the duties of the managers. |
| Reason for Adding to DB |
Example of accident caused due to an inadequate plan on a capacity of a facility |
| Scenario |
| Primary Scenario
|
Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Organizational Problems, Inflexible Management Structure, Insufficient Education/Training, Carelessness, Insufficient Precaution, Carelessness of Operator, Planning and Design, Poor Planning, Poor Production Planning, Regular Operation, Erroneous Operation, Over Supply, Bad Event, Chemical Phenomenon, Abnormal Reaction, Secondary Damage, External Damage, Fire, Loss to Organization, Economic Loss, Direct Monetary Damage 10 million yen
|
|
| Sources |
Fire and Disaster Management Agency, Major accident case, Hydrogen explosion and fire in workshop, Accident cases of dangerous materials, pp.34, 366-367
|
| Physical Damage |
Slight fire at a workshop, 10 square meters burned. Damage to shutters and windows. |
| Financial Cost |
¥ 10 million. (Accident cases of dangerous materials) |
| Multimedia Files |
Fig4.Chemical formula
|
|
Fig5.Chemical formula
|
| Notes |
Formation of combustible gas-air mixture |
| Field |
Chemicals and Plants
|
| Author |
WADA, Yuji (National Institute of Advanced Industrial Science and Technology)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
|
