Fire in the Hydrogenation Reactor of a Alcohols an Acids Production Plant
A fire started on the primary hydrogenation reactor of a chemical plant synthesizing alcohols and acids by reactions between olefins and a H2 / CO gas mixtures. The alcohols are synthesised in 3 steps: HP (280b) / BP (3b) ozonisation, primary hydrogenation (63b), vacuum distillation and final hydrogenation (63b).A pressure drop was noted on the hydrogenation unit, caused by a leak from a thermally insulated pipe (DN 50, 3.6 mm). The pipe was containing hydrogen at 40 bar and was connected to a separator. The unit was depressurized, but 15 minutes later the hydrogen ignited generating a jet fire directed towards the inside of the unit. The emergency plan was triggered, with four water jets cooling the unit. The fire was put under control by means of fire extinguishers do that the firefighters did not need to intervene.Property damage and environmental impact (smoke) were limited.An investigation of the pipe has revealed a 30 mm long crack perpendicular to the axis of the pipe in the outer part of an elbow, corrosion I nth direction of the flange of connection with the condenser and also internal corrosion at the elbow. The pipeline was corroded / eroded and the stresses due to insufficient support weakened the elbow. Thickness checks were carried out, the pipe was replaced (5.6 mm thick) and a suitable support was put in place.
Event Date
October 8, 2001
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
Immediate cause was the self-ignition of hydrogen released via a crack in a pipe. The crack was probably caused by corrosion and consequent reduction of the stress-bearing section of the pipe.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
hydrogen pipe, hydrogenation reactor
Storage/Process Medium
Design Pressure
40
Location Type
Location description
Industrial Area
Pre-event Summary
A depressurization of the hydrogen pipe was performed, following the detection of a pressure drop.
Consequences
Number of Injured Persons
2
Lessons Learned
Lessons Learned
Since the cause was failure to bear stress at a corroded pipe elbow, a thicker tube was used to replace the cracked pipe (5.6 mm thick instead of 3.6) and a suitable support was put in place to reduce stress at the elbow. .
Event Nature
Emergency Action
2:40 The unit is depressurized 2:55 (15 minutes later) the hydrogen ignites by self-heating generating a torch fire directed towards the inside of the unit. The emergency plan is triggered, with four water jets cooling the unit. 3:15 Fire under control by means of fire extinguishers. 3:10, The firefighters arrive to the scene but do not intervene 3:30 The emergency plan is called off .
Release Type
Release Substance
Release Pressure (bar)
40.00
Ignition Source
Ignition Delay (s)
900
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Flame Type
Source Category
References
References
ARIA data base
event no. 21196