Explosion at a Hydrogen Production Unit
The explosion occurred at the hydrogen producing unit of a refinery.A solution of potassium carbonate was being drawn off from an absorption tower to a temporary storage tank for a turnaround shutdown maintenance. The tank exploded, due to backflow of hydrogen into the tank. The level of the solution in the tower was not checked. When a water solution in an absorption tower for carbonic acid gas is drawn off, the water level of the solution drops. This drop \was ignored and the pump cavitated. Since the pump and a transfer valve were not shut down immediately, hydrogen in the absorption tower flowed into the tank. The hydrogen ignited in the tank, probably due to spark at the wall surface or the solution surface. The force of the flow blew off scales, coarse particulates, and solution in the tank.SEQUENCEOn May 23rd , 1996: operation was stopped.7:05 on 24th; the shift changed7:30; a meeting about turnaround shutdown maintenance was held.About 8:00; the meeting finished and operators in charge of solution draw-off read out and collated an operation manual for twenty minutes.About 8:10; a potassium carbonate water solution started to be drawn off into an inventory tank. As a pump cavitation occurred, a delivery valve was adjusted, but the pump continued to cavitate, so the pump was stopped and draw-off work was also suspended. About 8:15; the tank exploded. Its roof was scattered around the sites of neighboring offices, and office buildings and vehicles were damaged by a blast.
Event Date
June 24, 1996
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
The immediate/direct cause was due to the fact that the workers neglected to check the liquid level of the tower. They also did not handle properly when the pump started cavitating. It is unclear why they did not shut it down.Moreover, since residual hydrogen was still present in the absorption tower, it should have been purged with nitrogen before starting the shutdown. Although the guidelines for shutdown were prescribing the actions requited, which were not executed, a contribution to the root cause could be related to shortcoming in the management, which made depend exclusively on manual, cumbersome operations the risks prevention.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
potassium carbonate tank
Storage/Process Medium
Location Type
Location description
Industrial Area
Operational Condition
Pre-event Summary
The facility was bein shut down for regular maintenance.
Post-event Summary
One worker was slightly injured, massive damage to the test facility, a very small fire.
Lessons Learned
Lessons Learned
LESSON LEARNEDComplex operations, and especially those of maintenance, which are not executed frequently, should not depends exclusively on the correct performance of workers, without additional safeguards or automatic controls. CORRECTIVE MEASURESTh operation of draw-off operations should be improved. The procedural handbook should be reviewed and make clearer. Training and education on compliance with the operation manual should be carried out.
Event Nature
Emergency Action
None
Release Substance
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
JST failures database:
https://www.shippai.org/fkd/en/cfen/CC1200118.html
(accessed Dec 2023)