Dairy Industry Systems Consultant
Checklist Development as an
Aid to Auditing Industrial
Processes Involving
Combustible D...
Dairy Industry Systems Consultant
Summary
This presentation uses spray dried food products to
illustrate how systematicall...
Dairy Industry Systems Consultant
Introduction
There are obvious hazards from a fire or deflagration
within process equipm...
Dairy Industry Systems Consultant
Introduction
Secondary explosions are responsible for most
injuries and deaths, so it is...
Dairy Industry Systems Consultant
Introduction
There are other hazards, however. These include:
• Falling from buildings w...
Dairy Industry Systems Consultant
Introduction
A final category of hazard is associated with fire
and explosion protective...
Dairy Industry Systems Consultant
The Milkpowder
Industry
Dairy Industry Systems Consultant
Milkpowder Plants
The New Zealand dairy industry spray dries over
1.2 million tonnes of ...
Dairy Industry Systems Consultant
Spray Driers
Dairy spray driers are basically large stainless steel
chambers supplied wi...
Dairy Industry Systems Consultant
Some drier designs with separate fluid beds.
Spray Driers
Checklists for Explosion Hazar...
Dairy Industry Systems Consultant
Some drier designs with integrated fluid beds.
Spray Driers
Checklists for Explosion Haz...
Dairy Industry Systems Consultant
Checklists
Checklists are an invaluable safety tool in many
circumstances where a comple...
Dairy Industry Systems Consultant
Checklists
Safety audits or full-blown hazard and operability
(HAZOP) studies are carrie...
Dairy Industry Systems Consultant
Checklists
In the course of carrying out many safety audits and
HAZOP studies in the mil...
Dairy Industry Systems Consultant
Oxygen
Fuel Heat
Dispersion Confinement
Checklists
Deflagrations are powder fires with t...
Dairy Industry Systems Consultant
Checklists
This presentation illustrates my approach using
milkpowder plants as examples...
Dairy Industry Systems Consultant
Checklists
4. Places where a deflagration could escape from
the process.
5. Isolation be...
Dairy Industry Systems Consultant
Dust
Concentration
Dairy Industry Systems Consultant
Dust Concentration
In many cases it is possible to calculate the
average powder concentr...
Dairy Industry Systems Consultant
Calculating Dust Concentrations - Chambers
The average concentration of powder in the ai...
Dairy Industry Systems Consultant
Calculating Dust Concentrations - Chambers
3. The amount of drying air needed to evapora...
Dairy Industry Systems Consultant
Calculating Dust Concentrations - Chambers
The previous analysis takes no account of any...
Dairy Industry Systems Consultant
Calculating Dust Concentrations - Fluid Beds
The average concentration of powder in the ...
Dairy Industry Systems Consultant
Calculating Dust Concentrations - Cyclones
Cyclones typically lose less than 1% of fat c...
Dairy Industry Systems Consultant
Calculating Dust Concentrations - Baghouses
Baghouses typically lose less than 20 mg/m3 ...
Dairy Industry Systems Consultant
Calculating Dust Concentrations - Baghouses
1. When there are cyclones upstream of
bagho...
Dairy Industry Systems Consultant
Calculating Dust Concentrations - Bins
Powder bins, silos and hoppers will contain airbo...
Dairy Industry Systems Consultant
Ignition
Sources
Dairy Industry Systems Consultant
• Flames
• Hot Surfaces
• Mechanical Friction
• Impact Sparks
• Electrical Sparks
• Elec...
Dairy Industry Systems Consultant
All of the external sources can be addressed by
administrative controls such as:
• no-sm...
Dairy Industry Systems Consultant
Self-ignition can be addressed by the use of:
• CO monitoring
• CCTV cameras looking at ...
Dairy Industry Systems Consultant
Explosion Venting
(Accidental and
Deliberate)
Dairy Industry Systems Consultant
Accidental Venting
Accidental venting can injure staff and trigger
secondary explosions ...
Dairy Industry Systems Consultant
Accidental Venting
Accidental venting can also occur from:
• Gaps between explosion vent...
Dairy Industry Systems Consultant
Deliberate Venting
Deliberate venting must discharge safely.
Vents discharging close to ...
Dairy Industry Systems Consultant
Deliberate Venting
Vent ducts must be as strong as the vessels they
protect.
Vent duct a...
Dairy Industry Systems Consultant
Explosion
Isolation
Dairy Industry Systems Consultant
Explosion Isolation
Where practicable, a deflagration in one part of a
process should no...
Dairy Industry Systems Consultant
Explosion Isolation
Slam-shut non-return or diverter valves may be
used to isolate dust ...
Dairy Industry Systems Consultant
Examples
Dairy Industry Systems Consultant
Spray Driers
In the following examples the checklists contain
different types of informa...
Dairy Industry Systems Consultant
Air
Heaters
Checklists for Explosion Hazard Auditing
Dairy Industry Systems Consultant
Drying
Chambers
Checklists for Explosion Hazard Auditing
Dairy Industry Systems Consultant
Baghouses
Checklists for Explosion Hazard Auditing
Dairy Industry Systems Consultant
Baghouses
Checklists for Explosion Hazard Auditing
Dairy Industry Systems Consultant
CONCLUSION
Dairy Industry Systems Consultant
Checklists for Explosion Hazard Auditing
This presentation has only begun to examine
all...
Dairy Industry Systems Consultant
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Chris Bloore - Dairy Industry - Checklist development as an aid to auditing industrial processes involving combustible dusts

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Chris Bloore delivered the presentation at the 2014 Dust Explosions Conference.

The 2014 Dust Explosions Conference examined industrial hazards, the means to control or eliminate dust and analysed the latest technology to ensure the maximum protection and safety of organizations. The event also featured recent industrial case studies and new safety recommendations.

For more information about the event, please visit: http://www.informa.com.au/dust14

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Chris Bloore - Dairy Industry - Checklist development as an aid to auditing industrial processes involving combustible dusts

  1. 1. Dairy Industry Systems Consultant Checklist Development as an Aid to Auditing Industrial Processes Involving Combustible Dusts Dr Chris Bloore Dairy Industry Systems Consultant 2014
  2. 2. Dairy Industry Systems Consultant Summary This presentation uses spray dried food products to illustrate how systematically creating a checklist allows potential safety hazards to be identified. The result is a greatly simplified HAZOP procedure. The real value of this approach does not lie in "ticking boxes", but rather in the systematic process of identifying boxes that may need ticking. Checklists for Explosion Hazard Auditing
  3. 3. Dairy Industry Systems Consultant Introduction There are obvious hazards from a fire or deflagration within process equipment. These include primary events such as: • Flames emerging into occupied spaces. • Loose items becoming missiles. • Smoke filling buildings, impeding evacuation. Checklists for Explosion Hazard Auditing
  4. 4. Dairy Industry Systems Consultant Introduction Secondary explosions are responsible for most injuries and deaths, so it is important to prevent deflagrations escaping from process equipment and to minimise potential fuel within buildings by good housekeeping. Checklists for Explosion Hazard Auditing
  5. 5. Dairy Industry Systems Consultant Introduction There are other hazards, however. These include: • Falling from buildings while replacing explosion panels. • Explosion vent duct heaters igniting dust within the vent duct. • Explosion vents discharging on to catwalks and stairs. Checklists for Explosion Hazard Auditing
  6. 6. Dairy Industry Systems Consultant Introduction A final category of hazard is associated with fire and explosion protective systems. These include: • CO2 fire suppression systems which create a dust cloud which then explodes. • Dry powder or pressurised hot water explosion suppression systems which activate while personnel are inside process equipment. • Mechanical failure of vessels caused by the weight of firefighting water. Checklists for Explosion Hazard Auditing
  7. 7. Dairy Industry Systems Consultant The Milkpowder Industry
  8. 8. Dairy Industry Systems Consultant Milkpowder Plants The New Zealand dairy industry spray dries over 1.2 million tonnes of milkpowder annually, earning about 10% of its total export income. The Australian dairy industry makes about half this amount. Parts of spray driers contain an explosible mixture of powder and air whenever the plant is operating. Fires and dust explosions are a real hazard in milkpowder production, and several incidents take place every year. Checklists for Explosion Hazard Auditing
  9. 9. Dairy Industry Systems Consultant Spray Driers Dairy spray driers are basically large stainless steel chambers supplied with large amounts of hot air. Concentrated milk is sprayed into the air, where it dries to a powder in about 30 seconds. Most spray driers have one or more fluidised bed secondary driers to complete the drying of the powder over 15 to 30 minutes by blowing warm air up through a layer of powder about 150 mm thick. Some driers have such a bed built into the bottom of their chambers. Checklists for Explosion Hazard Auditing
  10. 10. Dairy Industry Systems Consultant Some drier designs with separate fluid beds. Spray Driers Checklists for Explosion Hazard Auditing
  11. 11. Dairy Industry Systems Consultant Some drier designs with integrated fluid beds. Spray Driers Checklists for Explosion Hazard Auditing
  12. 12. Dairy Industry Systems Consultant Checklists Checklists are an invaluable safety tool in many circumstances where a complex series of actions and checks must be performed on a regular basis. The classic case is the aviation industry. Aircraft operation and maintenance involve repetitive procedures which must be rigidly adhered to. Can checklists be applied to fire and explosion safety audits? Checklists for Explosion Hazard Auditing
  13. 13. Dairy Industry Systems Consultant Checklists Safety audits or full-blown hazard and operability (HAZOP) studies are carried out at the design review stage of new process plant installations, and when engineering or procedural changes are made to existing installations. Every process plant installation is unique. While many features are similar to those of other installations, each must be considered on its own in some detail. Checklists for Explosion Hazard Auditing
  14. 14. Dairy Industry Systems Consultant Checklists In the course of carrying out many safety audits and HAZOP studies in the milkpowder industry, I have found the process of developing a checklist to be very helpful. Many dairy companies have multiple sites with multiple dryers. Taking a checklist from one site to another helps focus on the common hazards and highlights the differences between dryers and sites. These differences include staff attitudes and experience. Checklists for Explosion Hazard Auditing
  15. 15. Dairy Industry Systems Consultant Oxygen Fuel Heat Dispersion Confinement Checklists Deflagrations are powder fires with two extra features, so the first step is to identify areas with dispersed powder and potential ignition sources. Checklists for Explosion Hazard Auditing
  16. 16. Dairy Industry Systems Consultant Checklists This presentation illustrates my approach using milkpowder plants as examples. A relatively small number of common issues appear in various combinations: 1. Dust concentrations in normal operation. 2. Abnormal events which can cause dust clouds. 3. Potential ignition sources, both external and due to self-heating. Checklists for Explosion Hazard Auditing
  17. 17. Dairy Industry Systems Consultant Checklists 4. Places where a deflagration could escape from the process. 5. Isolation between various equipment items. 6. The adequacy of any venting or suppression systems. 7. Means of egress for staff. 8. Hazards associated with firefighting. 9. Hazards associated with reinstatement of plant following an incident. Checklists for Explosion Hazard Auditing
  18. 18. Dairy Industry Systems Consultant Dust Concentration
  19. 19. Dairy Industry Systems Consultant Dust Concentration In many cases it is possible to calculate the average powder concentration in spray dryers and fluid bed dryers, and in dust collection equipment such as cyclones and baghouses. In other cases, experience allows a reasonably accurate assessment of the normal concentration of powder in the air within plant items. In all these cases, normal operation is assumed. Checklists for Explosion Hazard Auditing
  20. 20. Dairy Industry Systems Consultant Calculating Dust Concentrations - Chambers The average concentration of powder in the air within a spray dryer chamber may be calculated by a heat and mass balance: 1. The amount of energy needed to heat up and evaporate 1 kg of water is: Dhevap = 2256.7+4.219*(100-Tfeed) kJ/kg 2. The amount of energy released by 1 kg of air as it cools from the dryer inlet temperature to the outlet temperature is: Dhair = Cp*(Tinlet -Toutlet) kJ/kg Checklists for Explosion Hazard Auditing
  21. 21. Dairy Industry Systems Consultant Calculating Dust Concentrations - Chambers 3. The amount of drying air needed to evaporate 1 kg of water is: Air = Dhevap/Dhair kg 4. The amount of powder produced by evaporating 1 kg of water is: Powder =TS/(100-TS-Moisture) kg 5. The amount of powder per kg of air is: Concmass = Powder/Air kg/kg 6. The amount of powder per m3 of air is: Concvolume = 1000*Densityair/Concmass g/m3 Checklists for Explosion Hazard Auditing
  22. 22. Dairy Industry Systems Consultant Calculating Dust Concentrations - Chambers The previous analysis takes no account of any fines being returned to the chamber. Checklists for Explosion Hazard Auditing
  23. 23. Dairy Industry Systems Consultant Calculating Dust Concentrations - Fluid Beds The average concentration of powder in the air within a fluid bed secondary dryer chamber is very low, but there are two places where it may become significant: 1. A thin (10-15 mm) layer of powder in ballistic trajectories above the bed. This represents less than 1% of the volume of the bed headspace. 2. A dust cloud around 1 m3 in volume where fines are returned to one or both ends of the bed. This represents less than 10-15% of the volume of the bed headspace. Checklists for Explosion Hazard Auditing
  24. 24. Dairy Industry Systems Consultant Calculating Dust Concentrations - Cyclones Cyclones typically lose less than 1% of fat containing powders and less than 1.5% of low fat powders. Most of the powder in cyclones spirals down the walls, leaving the bulk of the volume occupied by air with at most 1.5% of the concentration in the air entering the cyclone. In many dryers much of the air falls on to a fluid bed and does not even reach the cyclone(s). Checklists for Explosion Hazard Auditing
  25. 25. Dairy Industry Systems Consultant Calculating Dust Concentrations - Baghouses Baghouses typically lose less than 20 mg/m3 to comply with emission limits. Powder concentrations in the inlet air will depend on whether there are cyclones installed ahead of the baghouse. Checklists for Explosion Hazard Auditing
  26. 26. Dairy Industry Systems Consultant Calculating Dust Concentrations - Baghouses 1. When there are cyclones upstream of baghouses, the average powder concentration within the baghouse will be very low. Dust will be briefly present only when a row of bags is pulsed, and then only near the bottom powder outlet. 2. When all the air goes directly to a baghouse, the average concentration will be similar to that in the chamber exhaust. Checklists for Explosion Hazard Auditing
  27. 27. Dairy Industry Systems Consultant Calculating Dust Concentrations - Bins Powder bins, silos and hoppers will contain airborne powder only while being filled. Lean phase pneumatic transport will create a significant powder concentration in the headspace. Gravity filling and the use of vacuum transport systems will create much lower, but still potentially hazardous concentrations. Checklists for Explosion Hazard Auditing
  28. 28. Dairy Industry Systems Consultant Ignition Sources
  29. 29. Dairy Industry Systems Consultant • Flames • Hot Surfaces • Mechanical Friction • Impact Sparks • Electrical Sparks • Electrostatic Discharge Sparks (but not in milkpowder) • Hot Work • Self-Ignition Ignition Sources Each of the following ignition sources has set off fires or dust explosions Checklists for Explosion Hazard Auditing
  30. 30. Dairy Industry Systems Consultant All of the external sources can be addressed by administrative controls such as: • no-smoking policies • hot work permit systems • good maintenance • appropriate wiring practices • appropriately rated tools and portable equipment • tight housekeeping protocols Checklists for Explosion Hazard Auditing
  31. 31. Dairy Industry Systems Consultant Self-ignition can be addressed by the use of: • CO monitoring • CCTV cameras looking at trouble spots in dryers • Routine inspections by operators • Infra-red detectors Checklists for Explosion Hazard Auditing
  32. 32. Dairy Industry Systems Consultant Explosion Venting (Accidental and Deliberate)
  33. 33. Dairy Industry Systems Consultant Accidental Venting Accidental venting can injure staff and trigger secondary explosions in buildings. The strength of the following items must be checked: • Flexible connections (“socks” or “boots”) • The ends of fluid beds • All access hatches Use explosion resistant couplings, blast shields and reinforce vessels and hatches as required. Checklists for Explosion Hazard Auditing
  34. 34. Dairy Industry Systems Consultant Accidental Venting Accidental venting can also occur from: • Gaps between explosion vent ducts and the vessel they protect or the building wall. • Poorly fitted doors and hatches. • Unsecured disk atomisers Checklists for Explosion Hazard Auditing
  35. 35. Dairy Industry Systems Consultant Deliberate Venting Deliberate venting must discharge safely. Vents discharging close to stairways and catwalks require shielding. Vent ducts require heating to prevent cool spots which increase the local relative humidity, attract powder deposits and encourage self-heating. Vent duct heating systems should not become ignition sources! Checklists for Explosion Hazard Auditing
  36. 36. Dairy Industry Systems Consultant Deliberate Venting Vent ducts must be as strong as the vessels they protect. Vent duct access doors must be secure and interlocked to stop the plant if opened. Signage must be appropriate, warning of a confined space and an explosion hazard. Handrails should protect staff inside the duct replacing panels or shutting doors from falling out of the building. Checklists for Explosion Hazard Auditing
  37. 37. Dairy Industry Systems Consultant Explosion Isolation
  38. 38. Dairy Industry Systems Consultant Explosion Isolation Where practicable, a deflagration in one part of a process should not be able to propagate to other parts. Dry powder or pressurised hot water suppression bottles installed in air ducts may be used to isolate dryers from baghouses. Rotary valves may be used to isolate powder discharges from dryers, fluid beds, cyclones and baghouses. Checklists for Explosion Hazard Auditing
  39. 39. Dairy Industry Systems Consultant Explosion Isolation Slam-shut non-return or diverter valves may be used to isolate dust collectors. Checklists for Explosion Hazard Auditing
  40. 40. Dairy Industry Systems Consultant Examples
  41. 41. Dairy Industry Systems Consultant Spray Driers In the following examples the checklists contain different types of information: 1.Descriptions of the plant configuration. 2.Descriptions of any safety related equipment. 3.Descriptions of access controls and signage. Checklists for Explosion Hazard Auditing
  42. 42. Dairy Industry Systems Consultant Air Heaters Checklists for Explosion Hazard Auditing
  43. 43. Dairy Industry Systems Consultant Drying Chambers Checklists for Explosion Hazard Auditing
  44. 44. Dairy Industry Systems Consultant Baghouses Checklists for Explosion Hazard Auditing
  45. 45. Dairy Industry Systems Consultant Baghouses Checklists for Explosion Hazard Auditing
  46. 46. Dairy Industry Systems Consultant CONCLUSION
  47. 47. Dairy Industry Systems Consultant Checklists for Explosion Hazard Auditing This presentation has only begun to examine all the possible explosion hazards and responses. The systematic creation of a checklist allows potential safety hazards to be identified in a simple, comprehensive way. The real value of this approach does not lie in "ticking boxes", but rather in the systematic process of identifying boxes that may need ticking.
  48. 48. Dairy Industry Systems Consultant

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