| Case Name |
Fire during renewal work of packing materials of a gasoline column at a ethylene manufacturing plant |
| Pictograph |
|
| Date |
May 16, 1991 |
| Place |
Kurashiki, Okayama, Japan |
| Location |
Chemical factory |
| Overview |
Polymers such as styrene and indene, which accumulated in the gasoline column of an ethylene plant, ignited at opening the column. It seems to have been resulted from plant modification, and the problem might be management of the change. A lack of checks on invisible parts of the process was a problem. |
| Incident |
There was a fire during turnaround shutdown maintenance at an ethylene manufacturing plant. Replacement of fillings in the gasoline column was planned at the shutdown maintenance. Steam-cleaning, nitrogen substitution, and water cleaning of the gasoline column were carried sequentially. A fire occurred from a polymer inside the column at the air substitution step after opening the upper manhole. |
| Processing |
Manufacture |
| Individual Process |
Maintenance |
| Process Flow |
Fig2.unit process flow
|
| Substance |
Styrene polymer |
| Indene polymer |
| Type of Accident |
Fire |
| Sequence |
May, 1989: Turnaround shutdown maintenance of the plant was carried out and no fouling was found inside the column.
About in May, 1990: There was a differential pressure rise in the column, which was regarded as indicating the presence of a polymer.
On March 18th, 1991: Instructions for turnaround shutdown maintenance in May was given; that is, maintenance work should be done under a wet condition when the inside of the column is exposed to air, because the polymer in the column might ignite with the air.
On May 10th: The plant was stopped for shutdown maintenance.
07:30: Nitrogen substitution finished, and elimination of combustible gas and liquid was confirmed.
13:00: The manhole of the gasoline column was opened after water cleaning.
20:30: Using an air mover, enforced substitution of air in the column started.
02:25 on May 16th: Black smoke and small flames were found at the gasoline column's upper manhole during patrol. |
| Cause |
Polymers such as styrene and indene adhered in large quantities at the packing layer at the upper part of a gasoline column in an ethylene plant. It is estimated that a fire broke out due to oxidizing of unsaturated polymers such as styrene and indene in sediment. There also seemed to be some hot spots in the column because of non-uniform cooling or non-equalized purging due to the effects of the polymer. |
| Countermeasures |
More thermometers have been mounted in the column, and temperature monitoring has been strengthened. |
| Knowledge Comment |
It is important to establish a system that checks the functional state of invisible parts of the process. It becomes important that dry parts should not be created in a distillation tower for materials easy to be polymerized. If accumulation cannot be avoided, the polymer can be flushed by a liquid flow. |
| Background |
There seems to have been a mistaken plant modification. A too small reflux volume or a failure of a distributor for a packing layer did not make the packing material surface sufficiently wet. Therefore, styrene or indene might have been polymerized on the packing surface, could not be flushed away, polymerization was promoted, and a self-heating polymer accumulated. As a polymerization catalyst, iron rust, which generated during previous turnaround shutdown maintenance, would have acted on the packing surface. Although they may be irresistible forces, considerations for liquid behavior in the packed column and polymerization characteristics of the substances might be insufficient. |
| Incidental Discussion |
Modification of the distillation tower in an ethylene plant from a tray column to a more efficient packed column was temporarily popular at that time. The modification reduced the reflux volume, but at the same time it seemed to generate sedimentation of self-heating styrene and indene polymers which easily polymerize, because the packing surface could not be flushed.
Still, among the materials described in information sources, only catalysis of iron rust has been raised, and it is considered that it was common even in the tray column before remodeling. The characteristics of a packed column should be reconsidered. |
| Reason for Adding to DB |
Example of fire caused due to excessive results of modification of a distillation column to a packed column |
| Scenario |
| Primary Scenario
|
Organizational Problems, Inflexible Management Structure, Insufficient Education/Training, Poor Value Perception, Poor Safety Awareness, Insufficient Safety Measure, Insufficient Analysis or Research, Insufficient Practice, Study with the Combination of Equipment with Treating Material, Planning and Design, Poor Planning, Poor Process Design, Bad Event, Chemical Phenomenon, Abnormal Reaction, Secondary Damage, External Damage, Fire
|
|
| Sources |
Fire and Disaster Management Agency, Generated fire during air substitution in the gasoline column of an ethylene plant. Accident cases of dangerous material.1991, pp.110-112.
High Pressure Gas Safety Inst. of Japan, Ethylene manufacturing plant, Fire in a column during packings renewal work in a gasoline column. Accident examples of Petroleum refinery and Petrochemical units, pp.117-122(1995).
|
| Physical Damage |
Deformation of a gasoline column in an ethylene plant and parts of contents and fillings of the column were damaged by fire. |
| Financial Cost |
¥ 50 million. (Fire and Disaster Management Agency). |
| 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)
|
|
