Increased Coal Dust Leads to Decreased Explosion Risk
Coal dust is created when coal is crushed, grinded or pulverized. If suspended in the air outside of a controlled environment of grinding and combustible equipment, coal dust is hazardous. This poses the risk of not only an explosive mixture in the air, but chronic illnesses in those who inhale excessive amounts of it.
High-capacity conveying systems handle thousands of tons of coal per hour. A small fraction of the particulate is released and becomes airborne, eventually settling on a variety of surfaces, creating a thick layer. Often times, these layers accumulate in inaccessible areas. A single spark is all it takes to cause a dust explosion that could put a plant out of service.
A utility company engaged with AAF to assist with the solution of coal dust collection. Our goal was to replace two indoor AmerPulse bag collectors from the 1970s. The collectors were collecting the coal dust from a material handling system in the bunkers underneath. They were looking to not only increase collection efficiency, but also to comply with the most current NFPA codes.
Since the PulsePak® Prime units were located inside, AAF and the customer agreed the chemical explosion suppression on the collector was the best route, as it was not possible to vent an explosion vent outdoors in accordance with NFPA standards. The power generating system operates 24 hours day. The demolition and installation took place over a two week shutdown, which meant delivery was critical.
The PulsePak® Prime units were utilized to replace the outdated bag collectors due to the great dust holding capacity and true downflow design that the customer requested. The system was designed so the footprint was equal or less than that of the original collectors. In order to fully comply with the relevant combustible dust requirements of NFPA 68 and NFPA 69, as well as prevent a fireball from returning through the air duct, chemical suppression was used in the inlet air duct. The cleaned air outlet was exhausted to the outdoors.
The utility company now has an industrial dust collection system that keeps workers safe and maintains good housekeeping, while also complying with OSHA, NFPA and EPA regulations.