Summary for bag house fire Discussion
Fire in bag house serving galvanizing line centers on Tom Traubert’s investigation of a baghouse fire on a pipe galvanizing line, where only the bags ignited and the rest of the system did not appear to burn. He asked whether moisture carry-over and cooling below the dew point from the blowing station could have caused the fire, noting superheated steam, heated air in the ductwork, a downstream centrifugal separator, and pulse-jet bag cleaning with refrigerated dryer air. The collected dust was expected to include zinc oxide, ammonium chloride, zinc chloride, and some zinc particles. In the discussion, Dr. Thomas Cook’s earlier warning about zinc dust reacting violently with water was referenced, but the excerpt provided does not show a final diagnosis or a confirmed cause. The main takeaway is that moisture and zinc-bearing dust were considered plausible contributors, but the thread excerpt stops short of proving the ignition mechanism.
April 3, 2014
Q. I read a post where Dr. Thomas Cook had indicated that the blowing (zinc) dust reacts violently when it comes in contact with water (letter 45817). I am working on an investigation that currently involves a fire at a bag house serving a pipe galvanizing line. Specifically, the bags ignited, nothing else appears to have combusted. The bag house is part of a system that collects fumes from the kettle and the pipe blowing station. Superheated steam is used in the blowing station with with heated air injected into the ductwork downstream of the blowing station to keep the fume temperature above the dew point. A centrifugal separator is located further downstream of the hot air injection point to remove any large zinc particles.
Have you seen situations of bag house fires due to moisture carry-over (i.e., temperature drops below the dew point) from the blowing station? Although the steam is superheated when it enters the pipes, it mixes with cold air at the fume collection hood and can be expected to cool to below the dew point along the duct work. The dust collected in the bag house is expected to be a combination of zinc oxide, ammonium chloride, zinc chloride, and zinc particles that pass beyond the separator. The bags are cleaned by air pulses – refrigerated driers on the air supply.
Thanks
Tom
Tom Traubert
– Windsor, Connecticut, USA