Mechanical Engineer of record for the mechanical systems incorporated to improve process safety
during the rebuild of a wood pellet port storage facility.
This included the design of a novel nitrogen inerting system to mitigate self-heating of stored
wood pellets via limiting the exposure to oxygen and moisture. I developed the system layout, the
flow and pressure requirements, and the orifice sizes. Under my direction a junior engineer
developed a flow model using AFT Arrow to verify the layout and system design. During design
development I created a plug flow gas mixing model to estimate the length of time which would be
required to purge the storage vessels with nitrogen. At a later time our nitrogen supplier
provided a CFD model of the expected nitrogen system performance as a function of injection time
which corresponded to my preliminary estimates, which provided additional confidence in system
function.
The storage vessels were previously vented to atmosphere, and as such needed to be modified to
keep the nitrogen gas from readily escaping. I designed a number of devices to seal the storage
vessels, including automatic vent dampers and barometric relief devices. In conjunction with PLC
control, these allow the vessels to be inerted after filling, while the passive nature of the
barometric relief devices mitigates risk of both excessive pressure or vacuum.
Because of the nature of the project, all of the design modifications needed approval of not only
the client, but also the AHJ and external stakeholders. This required substantial dialog regarding
the design intent.