Case Ditails

Scenario
Case Name Explosion and fire caused due to insufficient agitation of excessive charging quantity at a multi-purpose drug manufacturing reactor
Pictograph
Date March 17, 1991
Place Yokkaichi, Mie, Japan
Location Chemical factory
Overview At a cyano-norbornene manufacturing plant, a mixture of dicyclopentadiene and acrylonitrile was reacted by heating with agitation in a reactor. However, agitation was insufficient due to the excessive quantity charged, acrylonitrile locally reached a high density, the temperature rose, and a polymerization reaction started. Due to the accumulation of reaction heat, there was a runaway reaction, pressure in the reactor rose, the weakest part of the reactor shoulder cracked within a few minutes, vapor caused a vapor explosion, and the dispersed liquid ignited. The ignition source was considered to be a static electricity spark. The operation at the time was the second batch of newly consigned manufacture, and it is not known if there was sufficient information or an operating manual.
Incident Dicyclopentadiene, acrylonitrile, and hydroquinone (a stabilizer) were charged into a reactor for manufacturing cyano norbornene, which is an intermediate of industrial chemicals. There was an explosion with a big sound during a reaction at 164 °C and 0.8 MPaG. Blown-off liquid caught fire, which spread to the whole plant. The facilities were multi-purpose production facilities for manufacturing agrochemical intermediates and industrial chemicals, etc.
Processing Manufacture
Individual Process Feed and Charge
Chemical Reaction Addition runaway reaction due to excessive charging quantity.
Chemical Equation Fig2.Chemical reaction formula
Substance Dicyclopentadiene, Fig3
Acrylonitrile, Fig4
Cyanonorbornene, Fig5
Type of Accident Explosion, fire
Sequence At about 23:00 on March 16th, 1991, after charging dicyclopentadiene, acrylonitrile, and hydroquinone (a stabilizer) in the reactor, nitrogen substitution of the vapor phase was performed.
At 06:00 on March 17th, heating with steam started. The steam was stopped after the reactor was heated to 155 °C. Cooling of the reactor started by introducing cooling water because the reaction temperature reached 160 °C after 15 minutes. However, the temperature continued rising.
At about 09:15, an explosion and a fire occurred with a big sound during the reaction at 164 °C and 0.8 MPaG. Additional information is that the accident occurred in the second run of the cyano-norbornene manufacturing, which was scheduled for 3 days between March 15th and 17th.
Cause Raw materials of dicyclopentadiene and acrylonitrile were charged into the reactor at more than the planned quantity. The liquid temperature was raised to start the reaction. Although it was natural, the liquid specific gravity decreased, and the volume increased. Therefore, there was insufficient agitation at the upper part of the reactor. At the upper part of the reactor, a high-density phase of acrylonitrile, which is more hazardous, was generated locally, and a cooling capacity diminished. As a result, polymerization of acrylonitrile began, the temperature rose due to the accumulation of polymerization reaction heat, and a runaway reaction occurred. Internal pressure rose with a rapid temperature rise in the reactor. As a result, the pressure increased more than the limit pressure of the reactor, and a crack rupture was generated near the upper part of the reactor. At that time, the pressure in the reactor rapidly fell, and raw materials in the reactor caused a vapor explosion. The contents of the reactor dispersed, and static electricity was generated. The dispersed materials could have been ignited by a static
electricity spark.
Charging quantity of the first batch was 1700 kg, and that of the second batch was about 3100 kg. A temperature indicator was
mounted only at the lower part, so the temperature of the upper part
could not be observed.
Countermeasures Investigation of physical properties of materials at new development.
Proper operation management.
Knowledge Comment At a plant in the development stage, all safety conditions cannot be perfectly grasped, and instrumentation and measurement are not always sufficient. In such a case, the functions of agitation, cooling and so on have a larger capacity than those of a usual commercial plant. As operation skills have not been acquired thoroughly, especially for exothermic reactions, it is required to prepare suitable facilities and operation methods to prevent a runaway reaction.
The multi-purpose manufacturing unit does not have an optimum design for the manufacturing of a specific material. It requires more careful attention than the use of exclusive facilities.
Background 1. Lowering of specific gravity due to a temperature rise of the charged liquid seems not to have been predicted. In comparison with the structure of the reactor, the charging quantity was excessive. Agitation was done but operators did not understand agitation. With a general impeller agitator, effective agitation might be limited to the width of the impeller in the lower and upper parts of the agitator. It is considered that there was not a sufficient understanding of the handling of a reactor with an agitator.
2. A series of batch reactions at the time of the accident was the first operation of consigned manufacturing. There is a possibility that correct information on the reaction from the consignor was insufficient and/or the operation manual of the consignee side was improper.
3. The operation was based on production data from the consigning company. The consigning company might not have indicated sufficient conditions. It is difficult to understand the real and potential hazards of manufacture if there are no researchers or developers in a chemical plant.
It is doubtful whether sufficient information for securing safety was transmitted.
Reason for Adding to DB Runaway reaction due to excessive charging quantity
Scenario
Primary Scenario Poor Value Perception, Poor Safety Awareness, Inadequate Risk Recognition, Insufficient Analysis or Research, Insufficient Prior Research, Lack of Consideration about Reaction Danger at Condition Change, Additive Reaction, Planning and Design, Poor Planning, Poor Design, Regular Operation, Erroneous Operation, Excess Supply, Bad Event, Chemical Phenomenon, Abnormal Reaction, Secondary Damage, External Damage, Explosion, Bodily Harm, Injury, 2 person severely injured
Sources High Pressure Gas Safety Inst. of Japan, Explosion and fire at reactor in a manufacturing plant of CNN (Cyano norbornene). Accident Examples of Petroleum Refinery and Petrochemical units. pp.203-204 (1995).
Masamitsu Tamura, Masahide Wakakura, Explosion during manufacture of cyano norbornene. Reaction danger- Accident case and analysis - p.34 (1995).
Assoc. for Safety Techniques of Dangerous Materials, Cases of accidents with dangerous materials. Dangerous material accidents seminar, pp.78-79 (1996).
Fire and Disaster Management Agency, Cases of major accidents, JFC plant reactor fire and explosion. Accident case of dangerous materials. pp.30, 76-79 (1996)
Number of Injuries 2
Physical Damage One building of a JFC plant was totally destroyed. 7 buildings including a control room were damaged. Many chemicals were damaged.
Financial Cost ¥603 million. (Accident examples of dangerous materials. Fire and Disaster Management Agency)
Multimedia Files Fig3.Chemical formula
Fig4.Chemical formula
Fig5.Chemical formula
Field Chemicals and Plants
Author KOSEKI, Hirosi (National Research Institute of Fire and Disaster)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
Scenario