A natural gas feed preheater fire

This paper examines an incident in an ammonia plant which began when a leakage in the radiant section tube of a natural gas preheater ignited a small fire. The small fire ultimately developed into a major blaze which caused the leaky tube to burst resulting in the plant shutdown. A subsequent investigation revealed inadequate equipment safety procedures. These faulty measures included the bypassing of an instrument interlock system provided for the gas feed preheater. The bypass caused operational problems because two plants were operating from a single natural gas supply header. In the aftermath of the incident, the instrument interlock system of equipment was modified to handle an emergency shutdown in the affected plant safely and, in the process, avoid hampering other ammonia plants.