Innovative Dust Explosion Prevention Technology

Back in the 3rd Century B.C, around the same period that the Carthaginian general Hannibal made his epic crossing of the Alps from Spain to Italy atop war elephants, another great feat was accomplished with Archimedes invention of the screw pump or Archimedean screw.

This same invention, after surviving over 2,300 years of applications is still used today in industrial facilities moving bulk solids throughout the manufacturing process. Yet an even greater and more impossible task than Hannibal’s crossing of the Alps is attempting to minimize the generation of combustible dust during the manufacturing process, which creates a potentially explosive atmosphere when concentrations of dust reach explosive limits of minimum explosive concentrations (MEC)

Throughout 2008, over 200 combustible dust related fires and explosion occurred in the manufacturing, non-manufacturing, grain, and utility sectors. Many of these incidents occurred in the transport process; where bucket elevators, screw elevators, pneumatic conveyors and inclined belt conveyors where in the process of conveying particulate solids (bulk solids), that generated combustible dust.

Like Hannibal’s famous quotation, "We will either find a way, or make one.” Eventually sometime in the process, combustible dust will either find an ignition source or make one, such as through an electrostatic discharge to initiate a deflagration. This is where explosion prevention and mitigation best engineering practices comes into the story with reducing the probability of occurrence and minimizing the severity of ensuing combustible dust related fires and explosions.

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But suppose explosion prevention could inherently be designed into the process that transports bulk solids? Instead of, as now is the case, having a more costly explosion prevention engineering control measure, separate from the transport process.

It’s been a tough battle for all stakeholders in minimizing combustible dust hazards in the workplace. Along the way dust explosions and flash fires at subsonic speed continue to occur frequently in industrial settings causing hundreds of fatalities, injuries and adverse economic damage.

A monumental victory in preventing combustible dust explosions occurred in 2003, when inventor Peter Olds, an Australian, from Maryborough in Queensland developed the Vertical Bulk Material Conveyor Olds Elevator in his foundry as an alternative to an inclined screw conveyor. Which at the same time with its full-bore natural choke concept by inherent design isolates ignition and oxygen sources from completing the troublesome fire triangle and ensuing dust explosion.

Additional potential solutions in preventing and mitigating combustible dust related fires and explosion can be found through resources around the world with our global trading partners. Stakeholders in the United States are fortunate that Richard McIntosh has obtained the exclusive license of the Olds technology from the Australian inventor, Peter Olds, for utilization in the USA and Canada, which will assist in minimizing the occurrence of future dust explosions throughout industry.

Facility owners and managers are even more aware of the hazards of combustible dust with the reintroduction of the combustible dust bill, which was initated last year following the catastrophic Imperial Sugar Refinery sugar dust explosion. To minimize the generation of combustible dust and at the same time prevent combustible dust explosions as bulks solids are conveyed, an innovative solution with the Olds Elevator is an effective and cost efficient solution. Contact Olds Elevator today for additional information on how the combustible dust hazards of your process stream can be minimized with utilization of the full-bore natural choke technology of the Olds Elevator.

Resources

Developments in Bulk Material Elevation Technology
Preventing Grain Dust Explosions

BULKEX 2009

Centre for Bulk Solids and Particulate Technologies

Upside Down Combustible Dust Bill

Dust explosions garnered national attention this week with the catastrophic coal dust explosion at a Wisconsin coal-fired electrical energy plant in conjunction with the reintroduction of the combustible dust bill. While it is undisputed that worker protection is needed concerning combustible particulate solids that generate combustible dust in the manufacturing, non-manufacturing, and grain sectors. A question arises in the protective measures outlined in H.R. 849, “The Worker Protection Against Combustible Dust Explosions and Fires Act,” requiring the U.S. Occupational Safety and Health Administration (OSHA) to issue rules regulating combustible industrial dusts.

Stakeholders throughout the industrial sectors including the public must realize that dust explosions can never be totally prevented unless we completely shut down our manufacturing base and turn into a service based economy. For instance, we can learn from our New Zealand trading partner, where proactive dust explosion control measures are in place in protecting local and export industries.

Since instituting these control measures the amount of dust explosions have been constant as previously occurred without control measures. The only difference is the severity of these incidents have been reduced with measures like explosion venting and deflagration suppression best engineering practices.

Propagating Explosions
Combustible dust explosions follow under the subheading of propagating explosions quite similar to vapor cloud explosions in the refinery and petrochemicals sector where a combustion zone propagates at subsonic speeds wrecking havoc with the damaging effects of overpressure, thermal radiation, and ensuing projectiles. In March 2005, the catastrophic BP Texas City Refinery explosion is an example of a propagating vapor cloud explosion with similar damaging effects like the Imperial Sugar Refinery propagating dust explosion in February 2008.

Developing worker protection legislation in regards to combustible dust explosions as written in the current reintroduced bill fails to take into account many important aspects in providing basic layers of protection for the nation’s workforce. Additionally, solely utilizing the Chemical Safety Boards (CSB) recommendations as a template for the bill without taking into account many other life saving aspects of protection will not fully solve the problem of future incidents.

A good example is the recent catastrophic We Energies coal dust explosion that utilized national consensus National Fire Protection Association (NFPA) combustible dust standards as stipulated in the combustible dust bill, while implementing explosion control measures such as explosion ventilation panels that reduced the severity of the explosion. NFPA combustible dust standards provide excellent guidance in preventing and managing combustible dust fires and explosions but only to a certain level.

Not in Vicinity/In Vicinity Protection
Subsequently, there only so much that can feasibly be done in providing protection concerning life safety, structural integrity, and mission continuity. For instance, the NFPA combustible standard’s primary objectives are to protect occupants not in the immediate vicinity of an explosion and fire. The contractors that suffered burn injuries in the Wisconsin coal dust explosion were in the immediate vicinity and this is where the problem arises in the reintroduced combustible dust bill in not addressing other important issues.

A potential solution in addressing worker protection concerning combustible dust explosions and fires is incorporating key aspects of the OSHA Process Safety Management (PSM) standard. This might be difficult for many to envision since the PSM standard centers around over 130 highly hazardous chemicals (HHC) that are toxic, corrosive, and reactive.

Combustible dust does not fall into any of these categories. But is does fall under one category in the PSM, and that is the explosive effects quite similar to flammable liquids and gases that can cause propagating explosions. Laying aftermath pictures side by side of the BP Texas City incident and Imperial Sugar Refinery explosion would be difficult for many not familiar of the specific processes to differentiate the two. Both caused severe loss of life, injuries, and property damage.

Contractor Awareness
The OSHA PSM does address contractor participation such as ensuring that contractors attend training concerning the hazards of the perspective workplace. Since contractors work in the immediate vicinity of fire and explosion hazards the PSM standard would provide an appropriate basic layer of protection, where the NFPA combustible dust standard does not, with the conflicting objective of occupants not in the immediate vicinity. Why can’t all layers of protection be crafted into the combustible dust bill?

Better yet, instead of another form of costly regulation that creates an administrative overburden requiring a force of over 10,000 OSHA inspectors for implementation, formulate combustible dust workplace protection around the current OSHA Process Safety Management standard (PSM). There is no need to differentiate another propagating explosion as a separate entity when the issue has already been addressed with flammable gases in the current OSHA PSM standard.

In fact many dusts have deadly overpressure effects more damaging than flammable gases. So what’s the difference and why so much of a disconnect? Is loss of life, injuries, and adverse economic damage more important of an issue in the PSM refinery sector than in the manufacturing sector? It’s time the same level of protection be provided for all the nation’s workers.

Layers of Protection
Combining the protection measures of the national consensus NFPA combustible dust standards and the OSHA PSM standard would go a long way in providing appropriate layers of protection. Already the NFPA combustible dust standard outlines process hazard analysis, process safety information, management of change, and many other criteria quite similar to the current PSM standard.

It doesn’t make sense to reinvent the wheel when the protection measures in the current OSHA PSM could provide an excellent guidance in providing workplace protection for the manufacturing and non-manufacturing sectors concerning combustible dust, just like it currently does for the refinery and petrochemical sector. When many stakeholders fail to take into account, is that all the above falls under the same umbrella of propagating explosions.

Fires Now Explosions
To further complicate the confusion of combustible dust hazards is the profusion of misinformation that the media has recently been expounding on concerning over 350 combustible dust explosions since 1980. For instance, after the CSB Combustible Dust Hazard study, submitted to OSHA in 2006 it was 281 combustible dust explosions and fires from the 1980-2005 period.

Then after the June 2008, CBS 60 Minutes segment on combustible dust, the fires from the CSB Dust Hazard Study, all of a sudden evolved into explosions, with the fires not being reported through many media sources. Hence adding to misinformation like a propagating combustion zone where soon the next media outlet, like unreacted dust ahead of the reaction front, will be consumed with more misinformation.

Conflicting Research Data
Most of the combustible dust incidents are fires not explosions. For instance out of the over 150 incidents in 2008 occurring in the manufacturing and non-manufacturing sector only 30 were combustible dust explosions. But don’t get a false sense that this is a mediocre number, since many dust explosions where previously combustible dust related fires, months earlier in prior repeatable incidents.

Incident reporting as stipulated in the OSHA PSM standard would provide stakeholders with a better idea of the probability and severity of occurrences instead of solely relying on incomplete data from governmental and media reports in formulating occupational health and safety policy

Conclusion
There are many more aspects in formulating a solution in developing comprehensive occupational safety measures concerning the hazards of combustible dust in the workplace. Hopefully a few of the above issues will provide insight into the depth and breadth of the issue that at times is like peeling back the many layers of an onion.

The reintroduced combustible dust bill needs to be rewritten to incorporate all layers of safety and not just from the 30,000 foot view following the tragic Imperial Sugar Refinery dust explosion. The future of our nation’s workforce is at stake. Instead of the threat from outside as in Homeland Security regulations, we now have a threat from within. Question is, just how much resources we are all willing to put forward.

Dust Explosions Public Relations Priorities

Over that past couple weeks several dust explosions have occurred in facilities throughout the United States. These events mostly go unnoticed by the national media unless there are a multitude of injuries or fatalities like the recent coal-fired energy plant in Wisconsin that sustained a dust explosion in the dust collector, where several contractors sustained burn injuries.

Congressional leaders where quick to respond with a press release after the Wisconsin coal dust explosion with Representative Lynn Woolsey (D-CA), chair of the Workforce Protections Subcommittee, stating that, “ yesterdays accident was just another reminder of the unacceptable risk posed to workers by outdated regulations on combustible dust,”

This knee jerk emotional response to a multi-dimensional problem of dust explosions throughout our nation’s industrial sector where fuel and ignition sources are continually present does not fully address workplace protection measures that already are in place.

National Consensus Standards
For example, We Energies, the facility where the coal dust explosion occurred had already instituted proactive protective measures with national consensus good engineering practices in minimizing the probability and reducing the severity of dust explosion as outlined in the National Fire Protection Association (NFPA) combustible dust standards. Reading in between the lines of many news accounts the reader will find mention of explosion ventilation panels that vented the harmful overpressure effects of the explosion to safe levels, preventing the duct collector from fragmentating like a hand grenade.

Explosion ventilation panels ensure that after an explosion, life safety, structural integrity, and mission continuity of a facility is maintained. Unfortunately life safety was breached with the burn injuries to the contractors, yet the facility continued functioning in providing electricity to its customers. There is always a risk to workers when handling combustible particulate solids that generate combustible dust in the diverse spectrum of industries and injuries cannot be totally prevented, only minimized as was the case in this incident where fortunately there were no fatalities on site.

Reintroduction Combustible Dust Bill
Most importantly, the protective and mitigative control measures that We Energies utilized in protecting the worker from harm is in the same content of the recently reintroduced congressional bill that was initiated last year following the Imperial Sugar Refinery dust explosion. The Worker Protection Against Combustible Dust Explosions and Fires Act, H.R. 849, will require the U.S. Occupational Safety and Health Administration to issue rules regulating combustible dust in industry. The bill explicitly states that the proposed rules would be based on effective voluntary standards devised by the National Fire Protection Association. Ironically, We Energies are following the rules. So what outdated regulations on combustible dust, is the Congresswoman referring too?

Facilities that sustain dust explosions where injuries and fatalities occur are best served in providing complete transparency to the public, as We Energies has done, in sharing information to the media concerning protective administrative and engineering control measures that have been implemented such as the case with the explosions ventilation panels. Many coal fired electrical energy plants throughout the nation are collectively addressing combustible dust hazards through the PRB Coal Users Group in which We Energies and many other plants are alliance members.

Combustible Dust Industry Awareness
Most recently, several members of this alliance attended the Combustible Dust Hazard Awareness workshop, hosted by the Combustible Dust Policy Institute at the 4th Annual Industrial Fire, Safety, Security Conference in Houston, Texas February 3-6 2009 in the Reliant Center (next to the Astrodome). In addition to understanding how to identify, evaluate, and control combustible dust hazards at a facility, it is equally important after a major incident to provide the media essential information concerning the proactive control measures that were utilized.

Without this information, a negative reaction is likely to occur as is the case with the recent congressional press release that provides the public with an inaccurate depiction of the events. The Combustible Dust Policy Institute, with a diverse knowledge of combustible dust incidents and regulations, can assist all stakeholders when major catastrophic incidents occur in working collectively with public relations personnel in the development of positive proactive post incident media response.

Photo Credit: Enrique Rodriquez-Journal Sentinel

Resources:
Oak Creek Power Plant expansion
Journal Sentinel- excellent news coverage