Release at a Hydrocracker in a Refinery Plant
The event affected the hydrocracker unit. A sudden release into a cracker compressor flare header destroyed a safety relief valve and damaged a sight glass on a liquid collection pot. As a consequence, release of hydrogen rich vapour to atmosphere occurred, necessitating a shut down of the iso-cracker.The damage was limited to that previously described, and there were no injuries. The cracker was returned to service four days later.
Event Date
December 21, 1991
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
According to the ICHEME report (see reference), the immediate cause was an accumulation of liquid in the flare header. The problem was compounded by undersized header and piping, and triggered by unstable operating conditions. Considering the recommendations reported by the ICHEME report, it could be concluded that contributing or root causes were inadequacy of related design and of procedures.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
hydrocracker compressor and valve
Storage/Process Medium
Location Type
Location description
Industrial Area
Lessons Learned
Lessons Learned
The following recommendations are reported (ICHEME) as lesson learned:1. Drain drip pots frequently to prevent liquid build-up.2. Locate source(s) of liquid and remedy now, where possible, or during the shutdown.3. Ascertain any testing required for individuals exposed to high levels of noise or hazardous vapours.4. Redesign the liquid removal system to ensure no build-up.5. Redesign the flare header to reduce velocity and back pressure.6. Adjust the operating and emergency procedures to reflect the dangers of rapid feed rate changes.7. Review the maintenance requirements for compressor alarms and trips.8. Review the refinery quality control procedures for work done in outside workshops.
Event Nature
Emergency Action
Unknown
Release Type
Release Substance
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
Event description extracted from the UK database ICHEME in PDF
ICHEME database is no longer available for purchase, but data can be download as PDF for free.
https://www.icheme.org/knowledge/safety-centre/resources/accident-data/
(accessed October 2020)