Case Ditails

Scenario
Case Name Explosion and fire induced due to incompatible reactions of residual contaminant at an alkylaluminum manufacturing plant
Pictograph
Date July 17, 1996
Place Takaishi, Osaka, Japan
Location Chemical factory
Overview At an organometallic compound plant, residual impurities contaminated because of insufficient cleaning of the reactor. Therefore, an unusual reaction occurred, and the reactor exploded. A fire occurred.
Incident In a batch hydrogenation reactor at a multi-purpose plant, an explosion occurred during manufacturing of metallic hydride, leading to a fire. Thirteen workers of a subcontractor and factory employees at the site were injured, and the windows of public facilities and general housing within a radius of about 1 km were broken by a blast. The reactor contents were scattered in the vicinity, leading to a fire, and a transport container (cylinder) near the plant exploded, its debris was scattered in the vicinity. The damage spread. The following were manufactured in the reactor: sodium aluminum hydride (NAH) and sodium bis-2methoxyethoxy-aluminum hydride (SAH).
Processing Manufacture
Individual Process Reaction
Substance Sodium bis (2-methoxyethoxy) aluminum hydride. Fig.2
Sodium aluminum hydride, Fig.3
Tetrahydrofuran. Fig.4
Type of Accident Explosion, fire
Sequence In January, 1996, a SAH manufacturing process was changed for the second time, and a new manufacturing process started. Afterwards, SAH was manufactured in the intervals of manufacturing of NAH.
About 10:00 on July 17th, 1996, SAH and normal butyllithium (NBL) were being manufactured. There was a fire caused by an explosion near the hydrogenation reactor on the SAH manufacturing line. There was a loud sound, and flames and black smoke erupted. The private fire brigade turned out, and the fire station was notified of the fire immediately. Public fire engines dispersed chemical extinguishing agents and sprayed water to prevent the fire from spreading.
23:22. The fire was confirmed to have been extinguished.
Cause Tetrahydrofuran (THF) is used for the manufacture of NAH. THF is washed with toluene on switching to SAH manufacture. However, this time, washing was insufficient and a small amount of a residue remained. In NAH operation, NAH, etc. splashed and adhered to the wall surface in the gas phase. In SAH operation, the quantity of charged raw materials was not precisely grasped, and excessive sodium and aluminum were converted into NAH. On the day of the accident, NAH and THF adhered to the wall in the gas phase of the reactor, which were not expected to be there. An unexpected chemical reaction (an exothermic reaction) occurred due to a high temperature of 180 °C of the reactor jacket, and the temperature inside the reactor rose slightly. The temperature rise induced an exothermic decomposition of SAH, and the pressure inside the reactor rose rapidly. The hydrogenation reactor (CD-111) exploded, and there was a fire. It is estimated that reaction heat caused ignition.
Response Charging of raw materials was stopped.
Countermeasures To avoid unusual reactions such as the one that caused this accident, contamination of impurities are to be prevented including management of residual substances. Safety assessment of handled materials and appropriate quantitative management of materials are to be done.
Knowledge Comment It should be sufficiently recognized that contamination by impurities can cause a large-scale accident. Especially at multi-purpose facilities, residual substances require careful attention. The hazardous nature of the reaction and effects of impurities should have been predicted.
Background The fundamental factor of the accident was that material in the reactor induced an unusual reaction because of insufficient cleaning. After the accident, exothermic reaction experiments with NAH and THF, and exothermic decomposition experiments of SAH, etc. were carried out. It had been proved before the accident that NAH adheres to the wall surface in droplets, and it could be predicted that THF might remain. It is expected that appropriate countermeasures could be taken if there were closer cooperation between research and manufacturing sides.
Incidental Discussion This is an example of an accident occurring with a change of the reaction system. There are many examples of such accidents caused by failure in management of change.
Reason for Adding to DB Example of explosion and fire caused due to an incompatible reaction of residual material at a multi-purpose plant
Scenario
Primary Scenario Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Organizational Problems, Poor Management, Poor Operation Management, Carelessness, Insufficient Understanding, Carelessness of Operator, Usage, Operation/Use, Washing at Grade Change, Regular Operation, Erroneous Operation, Bad Event, Chemical Phenomenon, Abnormal Reaction, Secondary Damage, External Damage, Explosion/Fire, Bodily Harm, Death, Bodily Harm, Injury, 12 person injured, Loss to Organization, Economic Loss, Manetary Damage 210 million yen, Damage to Society, Social Systems Failure
Sources Fire and Disaster Management Agency. Explosion and Fire in alkylaluminum manufacturing plant. Accident cases of dangerous materials. 1996. pp.90-91.
The fire fighting union Fire-Defense Headquarters in Sakai City Takaishi City. Explosion and fire in metal hydride manufacturing plant. Dangerous material accident case seminar. pp.1-13(1997).
Shouzou Yanagida. Hirotaka Akatsuka. Explosion in hydrogenation reactor, etc. Safety engineering. No.202. pp.61-67(1998).
The Japan Soc. for Safety Engineering edition. Shouzou Yanagida. Hirotaka Akatsuka. Explosion in hydrogenation reactor, etc. Examples of fires and explosions. pp.24-30(2002).
Number of Injuries 13
Physical Damage Windows of 39 houses within a radius of 1 km were damaged. A building (160 square meters, steel-frame structure, three stories) was destroyed by fire. A laboratory was totally destroyed by fire. A compressor room was damaged by fire. Cylinders at an alkylaluminum container storage space were destroyed by fire. Slate side walls of an adjacent factory building were damaged.
Financial Cost ¥ 218 million yen. (Fire and Disaster Management Agency).
Consequences Traffic on the Han-Shin bay-coast expressway stopped. Children forced to remain at school at seven municipal elementary schools.
Multimedia Files Fig2.Chemical formula
Fig3.Chemical formula
Fig4.Chemical formula
Field Chemicals and Plants
Author DOBASHI, Ritsu (School of Engineering, The University of Tokyo)
YOSHINAGA, Jun (Graduate School of New Frontier Sciences, The University of Tokyo)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
Scenario