Application of Process Hazard Analysis and Inherently Safer Design in Wood Pellet Production

Wood pellets are a fuel used for heat and power generation. Wood pellets are manufactured from forest residues and byproducts of other sectors in the wood processing industry, such as sawmilling. Wood pellet production generates combustible wood dust, which presents the risk of fire and explosion. The objective of this research was to incorporate the principles of inherently safer design (ISD) for the management of combustible dust hazards associated with wood pellet production. Using bow tie analysis to explicitly consider ISD within process hazard analysis (PHA), ISD barriers were successfully identified, including the use of paved surfaces to store feedstock to minimize rocks entering the process and presenting a risk of ignition sources, the use of reduced-size silos to minimize the inventory and increase the turnover frequency, the removal of unnecessary or hazardous equipment, such as fans, following a redesign, and the relocation of hazardous equipment, such as cyclones, outside and away from personnel. A summary of example-based guidance for combustible dust hazards was collected to support additional ISD implementation within PHA as part of the process safety management (PSM). The research also highlights learnings for conducting virtual PHA workshops, as well as identifying opportunities for incorporating ISD within operating wood processing facilities through the incident investigation and risk assessment elements of PSM.