Challenges in the Design of Safe Handling System for Explosive …
453
3 Design of Explosive Dust Extraction System
During the pre-design phase, various hazards associated with explosive dust are
considered. All process industry accidents fall under three broad categories-fire,
explosion, and toxic release. Out of these three, fire is the most common occurrence
in the industries. Within this broad category there occur subcategories, each depicting
a specific sub-type of fire/explosion/toxic release. A bewildering variety of accidents
occur in various process industries during storage, manufacture and transportation
of different hazardous and toxic chemicals [1]. These accidents range from minor
innocuous leaks to catastrophic releases, barely noticed tiny sparks to all-consuming
fires and plop of a bubble to earth-shattering explosions [1].
It is a mechanical system designed with the right combination of different dustcollecting devices to suit the particular material dust with the highest efficiency. The
basic mechanisms of removing particulate matter from gas steams in dust collection
systems are gravitational settling, centrifugal impaction, inertial impaction, direct
interception, diffusion, electrostatic precipitation. Owing to the safety aspects and
functional requirements in the explosive handling areas the combination of dust
collectors is gravitational settling chamber, cyclonic chamber, scrubber and bag filter
are chosen for the extraction system.
Though the concept for dust collection looks simple, things can go wrong if
careful attention is not paid to the details. There are four key components in any
dust collection system filter, piping, pick up hood and air mover [2]. Dust collection
system components for various applications can be manufactured excellently that can
do their “intended job” but the key to a dust collection system is to get the system
components to work well together in a cohesive manner [2]. Dust that generates at
a point source is pulled into pick up hood that is the start of dust extraction system.
Air flow through the hood can be controlled either by blast gates or by pipe/duct
sizing. The dust collector operates either by inertial or physical barrier, means, for
example, a cloth “sock” or fabric or sintered metal, to retain the particles while the
air leaves to the air mover. The heart of the dust collection system is the air mover
and the filter combination [2, 3]. The symbiotic relationship between these two
components is important; for instance, if the filter is clogged with dust, the fan (air
mover) performance will likely be reduced and can cause major system problems [2].
Based on the expertise gained by the experts in the field of industrial dust collection
systems design and operations, design of a proper dust collection system may be
broken down to the following pivotal considerations.
• Adequate conveying velocity
• System balancing with the design
• Selection of correct air mover
• Prevent flow hindrances/plugging
• Selection of right component for collection
• Understanding on dust hazards.
453
3 Design of Explosive Dust Extraction System
During the pre-design phase, various hazards associated with explosive dust are
considered. All process industry accidents fall under three broad categories-fire,
explosion, and toxic release. Out of these three, fire is the most common occurrence
in the industries. Within this broad category there occur subcategories, each depicting
a specific sub-type of fire/explosion/toxic release. A bewildering variety of accidents
occur in various process industries during storage, manufacture and transportation
of different hazardous and toxic chemicals [1]. These accidents range from minor
innocuous leaks to catastrophic releases, barely noticed tiny sparks to all-consuming
fires and plop of a bubble to earth-shattering explosions [1].
It is a mechanical system designed with the right combination of different dustcollecting devices to suit the particular material dust with the highest efficiency. The
basic mechanisms of removing particulate matter from gas steams in dust collection
systems are gravitational settling, centrifugal impaction, inertial impaction, direct
interception, diffusion, electrostatic precipitation. Owing to the safety aspects and
functional requirements in the explosive handling areas the combination of dust
collectors is gravitational settling chamber, cyclonic chamber, scrubber and bag filter
are chosen for the extraction system.
Though the concept for dust collection looks simple, things can go wrong if
careful attention is not paid to the details. There are four key components in any
dust collection system filter, piping, pick up hood and air mover [2]. Dust collection
system components for various applications can be manufactured excellently that can
do their “intended job” but the key to a dust collection system is to get the system
components to work well together in a cohesive manner [2]. Dust that generates at
a point source is pulled into pick up hood that is the start of dust extraction system.
Air flow through the hood can be controlled either by blast gates or by pipe/duct
sizing. The dust collector operates either by inertial or physical barrier, means, for
example, a cloth “sock” or fabric or sintered metal, to retain the particles while the
air leaves to the air mover. The heart of the dust collection system is the air mover
and the filter combination [2, 3]. The symbiotic relationship between these two
components is important; for instance, if the filter is clogged with dust, the fan (air
mover) performance will likely be reduced and can cause major system problems [2].
Based on the expertise gained by the experts in the field of industrial dust collection
systems design and operations, design of a proper dust collection system may be
broken down to the following pivotal considerations.
• Adequate conveying velocity
• System balancing with the design
• Selection of correct air mover
• Prevent flow hindrances/plugging
• Selection of right component for collection
• Understanding on dust hazards.