Evaluation of Dust Explosion Hazards, Prevention, and Control Measures

This essay provides a comprehensive overview of dust explosions, focusing on their causes, consequences, and prevention strategies within industrial settings. It identifies key conditions necessary for dust explosions, including the presence of an oxidant, ignition source, dust dispersion, confinement, and combustible dust, further elaborating on specific ignition sources such as smoldering nests, hot surfaces, and electrostatic discharges. The essay highlights the significant industrial losses resulting from dust explosions, referencing a study that quantifies property damage across various sectors like woodworking, food processing, and metal processing. Furthermore, it details several prevention methods, including full confinement, ignition isolation, partial inerting, explosion discharging, and automatic explosion prevention, alongside essential controlling measures such as dust control, ignition control, explosion relief, and the use of personal protective equipment. The essay concludes by emphasizing the importance of adhering to safety laws and guidelines to mitigate the risks associated with dust explosions, ultimately aiming to protect equipment and personnel in hazardous environments; access more solved assignments and past papers on Desklib.

Introduction
The fast detonation of fine particles
hovering in the air often but not always in
an encompassed place is dust explosion. It
can take place where any isolated
powdered explosive material is present in
higher concentrations in the atmosphere or
other gaseous medium which are oxidized.

Combustible dust explosion
Primary dust explosion
Blast wave
Formation of dust cloud
Accumulation of dust
Secondary dust explosion
Heat created from primary
dust explosion sets fire to
dust cloud

Conditions for dust explosion
 Oxidant
Ignition source
Dust dispersion
Dust confinement
Combustible dust

Causes of dust explosion
 Smoldering nests
Hot surfaces
Burning particles
Electrostatic discharge between
two metal electrodes
Electrical apparatus

Smoldering nests
o Smoldering nests are formed from heat caused by friction such as
cutting, by the accumulation of powder, by heating which is linked
with hot work on tools and ducts that contains dust deposits and
by sources of heat that are small.
o According to the tabulation chart of ignition sources implicated in
426 German dust explosions from the year 1965 to 1985 written
by Eckhoff point out that smoldering nests were the most
ubiquitous cause of dust explosions in silos(28%), dryers(29%)
and the ignition source which is used as second most recurrent
source in dust collector explosions(11%) (Eckhoff 2013).
o According to Gummer and Lunn smoldering nests were bad
sources of ignition for dust clouds while flaming nests caused
ignition more rapidly(Fabiano et al 2014). A numerical method is
presented by Krause and Hensel through which non-steady fields
of temperature can be calculated (Murillo et al. 2013).

Electrostatic discharges
 Electrostatic release between two metal
electrodes can be created in a number of ways
such as by release of static electricity, failures in
electric circuits and in switch.
 Echkoff has discussed about the impact of dust
distinction on MIE of ferro-alloys dust (Holbrow
2013). The distinction of dust was specified only
as a percentage of mass better than a random
size in the past which complicated the analysis of
experimental data that was published and
research is required which will be more systematic
to elucidate the précised influence of particular
size.
 Lorenz and Schiebler investigated the
development of temperature as well as pressure in
the spark channel for the duration of its
configuration as well as its expansion (Xu et
al.2013). The cooling of the canal by the thermal
radiation and the reliable ability of a certain

Hot surfaces
 The temperature that is responsible for the hot surface
explosion of dust cloud has been considered as universal
constant for a specific cloud in past.
 Hot surface explosion temperatures of dust clouds which
are minimal differ drastically with scale along with the
geometry of the warm surface related to the dust cloud.
Both distinguished basic understanding and distinguished
testing approach are needed.
 There are certain materials that are susceptible to self
heating and can lead to impulsive blast-off. The principal
chemical reaction is low level oxidation and the materials
which can self heat by oxidation at low temperature are ABS
resin powder as well as activated carbon and other
chemical intermediates (Hedlund, Astad and Nichols 2014).

Reasons for dust explosion in Industries
 The dust collector deals with dust which
is always suspended in air.
The systems are designed to handle
equipments that are produced somewhere
else and the source of ignition may be
secluded from the dust collector.
 Flammable liquids and gases can cause
dust explosion in industries.

Industrial loses due to dust explosion
A study of losses due to dust explosion experienced by companies
warranted by Factory Mutual and its subsidiaries during 1983 till
2006 supplies some insight into the loss trends of explosions
related to dust (Addai, Gabel and Krause 2015).
There were 166 dust ignitions which resulted in $284 million in
loss of property during that period of time (Addai, Gabel and
Krause 2015).
Woodworking experienced the highest number of losses (38.5%)
which is followed by food processing (15.6%) and metal
processing (10.8%) out of those 166 incidents and these three
industries jointly report 65% of the incidents and the rest 35% of
dust explosions extended out among nine other industries (Addai,
Gabel and Krause 2015).

Combustible dust explosions by industry
Food
Wood
 Chemical
Metal
Plastics
Utility (Yuan 2015)
Paper
Non-manufacturing

Sub processes for both impact and
ignition
The explosion of the flying hot
element and the succeeding burning
method.
 The heat transmits to the dust cloud
which in due course determines
whether explosion occurs or not (Mittal
2013).
The creation and premature heating
of the metal element by the impact.