|Matrix CFD saves $0.5 million in equipment upgrades || || |
Oji Fibre Solutions (previously Carter Holt Harvey) is a leading producer of market pulp, paper and fibre based packaging. Beca AMEC are consultants providing engineering expertise to the Australian and New Zealand pulp and paper, wood products and bioprocess industries.
Plant operated by Oji Fibre Solutions Tasman mill produces hydrogen, which is
explosive at concentrations greater than 4% by volume. To mitigate the
risk of an explosion, in New Zealand the standard AS/NZS 60079.10.1 ("Classification
of areas – Explosive gas atmospheres") is mandated to be used to determine
areas where specialist explosion protected (Ex) equipment must be installed to
control any potential ignition sources. This equipment is expensive and the existing
hazardous area classification was thought to be overly conservative. If the
true size and extent of the explosive atmosphere could be determined more
accurately, this would help Oji Fibre Solutions make better decisions on where
to install this specialist equipment.
Beca AMEC’s process
and electrical engineers approached Matrix to develop a computational model of
a chlor-alkali plant to consider how hydrogen would build up inside the plant
under a range of different gas release scenarios. Matrix used a numerical
technique called computational fluid dynamics (CFD) to simulate the dispersion
of hydrogen inside the plant. This allowed Beca AMEC to visualise hydrogen
concentrations within the plant, more accurately define the hazardous areas and
make better decisions about where to install specialist Ex equipment.
The simulation work
clearly showed that hydrogen concentrations (depicted below) from any potential
gas releases drop quickly below the explosive limit. Even under a catastrophic
failure of the hydrogen cell the traditional approach to hazardous areas classification
would have provided an overly conservative hazardous area classification. The revised
classification enabled Oji Fibre Solutions to save an estimated $350,000 to
$550,000 in electrical equipment upgrades.