Fire - at the vent stack of a hydrochloric acid production plant

An operator had just replaced the ignition port cover on a hydrochloric acid plant burner. Normal start-up was continued by closing the drain valve in the product run off line and opening the combustion chamber condensate line.
At this point a passing mechanic noted that a three foot hydrogen flame was burning from the vent stack. The plant was shut down. No evidence of an explosion or internal burning was identified. No source of ignition was identified for the flame. A small amount of charring occurred on the UPVC stack.

no cause of the event was reported.
Probably H2 accumulated in the condensate line which was then burned at the vent stack

Reactor vent stack

An operator had just replaced the ignition port cover on a hydrochloric acid plant burner. Normal start-up was continued by closing the drain valve in the product run off line and opening the combustion chamber condensate line.