Dust Explosion by ogg48329

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									Dust Explosion


     - Mallika Gharpure
      Ravikumar gogar
      Trupti Gawai
      Gokul Gopal
       Samyak Gayakwad
              Introduction

What it is?
 Dispersion of powders in air

 Form of cloud

 Suitable concentration

 Presence of effective ignition source
          Where it can occur?


   Combustible powders
   Fine materials
   Foods, pharmaceuticals
   wood, plastics
   Metals, rubber
          How it can occur?

 Explosible Dust
 Particle size distribution for propagation of
  flame
 Presence of oxidant in atmosphere

 Dust cloud concentration within explosion
  range
 Ignition source
    What are the associated factors?

   Dust and explosion violence : pressure,
    speed
   Composition of Dust
   Particle Size
   Concentration of dispersed dust : LEL,UEL
    T, P, moisture content, scale of vessel
              Case Study

Process :
 equipment used to pulverize aluminum-
  alloy
 air recycled through a grinder, cyclone
  product separator, blower
 a side stream to extract undesired dust to
  a dust collector
           Batch To Continuous
   a much higher rate of dust generation
    high concentrations of very fine dust in the
    recycle stream
   accumulation of heat in the recycle stream.
    installer of the recycle system with no
    experience with combustible powders
   no explosion prevention or protection devices or
    systems provided.
                   The Accident
   concentration of dust in the circulating air stream above
    LEL in most of the recycle system
   relatively high temperature of the circulating air
   exothermic oxidation of accumulated combustible dust in
    the return-air ductwork
   an access door on the grinder forcibly ejected, the door
    struck the LPG cylinder on a nearby forklift truck.
    Escaping LPG vapors – ignited by the dust fireball from
    the open grinder door – resulted in a flash fire
   fatal burn injuries to the forklift driver
  lessons learned from this incident

(1)   Every significant change in a process should be
      subjected to a Management of Change analysis
(2)    Producers of hazardous materials (and
      particularly small-company producers) need to
      follow Codes and Standards that apply to their
      processes
(3)   Code-enforcing authorities should become
      more familiar with Codes and Standards that
      apply to dust-explosion hazards
(4)    Dust-explosion characteristics need to be
      included in Material Safety Data Sheets.
                   Dust Control

   Use dust collection systems and filters
   Utilize surfaces that minimize dust accumulation and
    facilitate cleaning
   Provide access to all hidden areas to permit inspection
   Inspect for dust residues in open and hidden areas, at
    regular intervals
   Use cleaning methods that do not generate dust clouds,
    if ignition sources are present
   Locate relief valves away from dust hazard areas
   Develop and implement a hazardous dust inspection,
    testing, housekeeping, and control program (preferably
    in writing with established frequency and methods).
              Ignition Control
   Use appropriate electrical equipment and wiring
    methods
   Control smoking, open flames, and sparks
   Control mechanical sparks and friction
   Use separator devices to remove foreign
    materials capable of igniting combustibles from
    process materials
   Separate heated surfaces from dusts
   Separate heating systems from dusts
   Proper use and type of industrial trucks
   Adequately maintain all the above equipment.
             Damage Control
   Separation of the hazard (isolate with distance)
   Segregation of the hazard (isolate with a barrier)
   Deflagration venting of a building, room, or area
   Pressure relief venting for equipment
   Provision of spark/ember detection and
    extinguishing systems
   Explosion protection systems
   Sprinkler systems
                        References

   ‘Dust Explosion Prevention and Protection’ By John Barton
   Process safety progress 2007, vol. 26, no4, pp. 324-329
   NFPA 654, Standard for the Prevention of Fire and Dust Explosions
    from the Manufacturing, Processing, and Handling of Combustible
    Particulate Solids
   Occupational Safety and Health Administration (OSHA), the
    Massachusetts Office of the State Fire
    Marshall, and the Springfield Arson and Bomb Squad. "Joint Foundry
    Explosion Investigation Team Report." OSHA, Springfield
Thank You….

								
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