DUST DISPERSION MODELING is an critical safety review required for protection of life, environment and assets. Dispersion of significant amounts and concentration of dust particles is a possible source of rapid combustion or explosion known as deflagration.
Dispersion of dust or particulate solids simply means suspension in the air. Confinement of dust in an enclosure could result in an increase in pressure which could cause an explosion. This is particularly true in the grain handling industry, processing industry, and mining industry; dust emission and accumulation are major concerns for the safety of workers and for explosion risks. The NFPA standards restrict thickness of dust layers on floors for fine powder materials such as to control the dust layer accumulation, dust dispersion patterns, and the properties of dust aerosols.
Deflagrations can be very destructive and difficult to control once it occurs. There is a high need to monitor processes and systems involving particulate solids or dusts for prevention of explosions. EXPLOSIVE ATMOSPHERES (ATEX) under the DIRECTIVE 2014/34/EU (RECAST OF 94/9/EC) OR ATEX 95 have applied some of these model provisions for explosion proof products. Other provisions for work safety in an explosive environment that applies dust dispersion modeling is DIRECTIVE 99/92/EC OR ATEX 137.
MODELING: The Discrete Phase Model (DPM) and the Computational Fluid Dynamics Model (CFD) give rise to a hybrid combination for modeling and simulation of dust dispersion from common sources of dust suspensions. This includes: AERMOD Cloud dispersion modeling system and FDMpro air quality model specifically designed for computing concentration and deposition impacts from fugitive dust sources.
DATA COLLECTION: Dust concentration in kilogram per cubic meter is sensed by gathering dust suspension from a dust injector into an enclosure at different dispersion rates and injection velocities. Large particles are more affected by gravitational force and inertia compared with small particles, settling with airflow after traveling. The smaller particles which experience bombardments due to its higher kinetic energy are more likely to cause explosions.
MATHEMATICAL MODELING OF DUST DISPERSION: Navier-Stokes equation based on Euler–Lagrange for polar coordinates and the standard k-e two equation model for turbulent flows in three-dimensional space with velocities u, v, and w in x, y, and z directions based on sum of the instantaneous pulsating speed and time-averaged speed respectively are very useful as adopted in computational sciences for WIND FLOW MODEL. DUST DISCRETE MODEL is computed for gas-solid two-phase flow discrete phase model simulation of dust particles.
In conclusion, there is a need for an operational process and systems involving handling of dust and particulate solids to design their dust control and explosion control systems by applying dust dispersion modeling in order to optimize designs, construction, production or manufacturing solutions.
The Environmental, Process and Passive Fire Safety Consultants, and Computational Scientists are better equipped to carry out dust dispersion modeling.
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APPLICABLE STANDARDS FOR DUST DISPERSION
- NFPA 660 Standard for Combustible Dusts.
- NFPA 69 Standard on Explosion Prevention Systems.
COMMON APPLICATIONS OF DUST DISPERSION MODELING
Increased levels of mechanization in the mining industry, such as coal mines, and quarries where dynamites are used for blasting of rocks, the risk for control of dust particles increases. - Ammonium nitrates used in the fertilizer industry.
- Low-freezing dynamites used in mining.
- Nitroglycerin production in the pharmaceutical industry.
- Black powder used as a pyrotechnic in quarry, match production, mining, pipeline construction, and road construction.
- Production of Chlorates and Perchlorates.
- Production of Nitrostarch, a secondary explosive known as white starch.
- Production of Ammonium Nitrate based explosives such as Nitramon and Nitramex.
