Industrial dust explosions threaten manufacturers' uptime

For years manufacturers have contended with industrial explosions from relatively unknown causes. Despite recent discoveries into dust explosions that have generated a wealth of new protection technology, most manufacturers remain in the dark about this serious problem and the available solutions.

For a CEO facing the stark reality of an uncontrolled dust explosion in one of his facilities or processes, the sheer complexity and unpredictable nature of these events is probably best defined by the late Dr. Carl Sagan in his award winning PBS documentary, Cosmos.  Dr. Sagan explained that the formation of the universe — the Big Bang — was essentially one gigantic explosion of dust and gas, expanding outward at nearly the speed of light.

Despite the more modest scale of a dust or gas deflagration in an industrial or material process, the damage they cause to people and property is all too real. While their complex nature is most visible in the potential number of overlapping factors that cause them, understanding and preventing these dangerous events is one of the most challenging tasks facing companies today.

Current statistical calculations estimate that the average manufacturing facility will have a dust explosion about every 20 years, while chemical, pharmaceutical and milling plants are likely to experience more frequent events. As major manufacturers become aware of this dangerous problem they are implementing safety programs to offset the potential hazard before a real disaster occurs. As many CEOs are discovering, the solution is akin to rocket science.

According to Franco Tamanini of Factory Mutual Research, a research scientist in the field of dust and gas explosions, process engineers depend on a complex body of standards and regulations created by organizations like the National Fire Protection Association (NFPA) in the United States and parallel organizations in Europe.

With a Harvard Ph.D. in applied physics, Tamanini is one of a select cadre of scientists worldwide that possess an advanced understanding of the processes underlying dust and gas events. As such, he supports the activities of the NFPA 68 committee steering ongoing standards development. By conveying research results obtained at Factory Mutual Research, an affiliate of commercial and industrial property insurer FM Global, his perspective is understandably neutral and influenced most strongly by science.

Existing in documents like NFPA 68 & 69, these guidelines include fairly rudimentary abstracts from combustion and explosion science to support the development of simple formulas and correlations for practical design application.

To protect both the lives of workers and the revenue stream fueling the company, safety-conscious managers often turn to specialized consultants and technology vendors to help them develop a strategy to reduce or even eliminate the underlying causes of the explosive events and increase process safety.

David Cvetas, president of Cv Technology, an explosion protection consultant company, provides a Sagan-like view of his own on the challenges facing CEOs and their process engineers: "Dust and gas explosions are beyond rocket science. You can aim a rocket.”

Based in West Palm Beach, Fla., Cv Technology provides engineering and consulting services for process evaluation and protection system design, to remove concerns about personnel safety, equipment protection and process continuity — the wells from which spring every company’s revenue stream.

The company has established itself as a leader in the introduction of dust and gas explosion protection technologies to major U.S. industrial and manufacturing companies.

Cvetas explains that his company has invested a great deal of time and effort investigating innovative technologies throughout U.S and European markets. This expands the range of possible protection solutions he can offer US clients, as part of what he emphatically terms a “non-intrusive” protection philosophy. Such technologies include the Q-Rohr, a quenching device originally developed by Rembe of Germany to enable safe indoor venting of process-driven dust explosions.

“When it comes to the best technology to address a protection issue, it's often not obvious what the best solution is," he said. "For example, if you have a piece of equipment inside a building, you have a list of at least four or five protection options you should consider. There may also be circumstances, which may be economic in nature, that will push you in a certain direction as opposed to another."

Despite the efforts of companies like Cv Technology to expand the protection options available to U.S. companies, many corporations are not only slow to accept the reality of the problem, but also unaware that a solution exists.

Procter & Gamble, however, has not only been open to this technology, they’ve helped to pioneer its use in the U.S. market, according to John McIntosh, a veteran process engineer at the manufacturing giant. 

As the global manager of health, safety & environment for P&G’s food and beverage division, responsible for the performance, training and development of P&G facilities worldwide, McIntosh is no stranger to dealing with dust and gas deflagrations. Cv Technology has worked with Procter & Gamble on a number of specific protection applications.

“One incident at a site in the early '90s that cost the company in excess of a million dollars was the catalyst for my initial contact with the Rembe technology,” McIntosh explained. “Fortunately, nobody was hurt, but there was a significant amount of equipment damage due to a deflagration.”

When the particular process, which was operating at several facilities, was evaluated, the incident history indicated that a fairly major deflagration occurred about every ten years. Harnessing P&G’s extensive incident database, they compiled a list of every facility incident stretching back over a 30-year period.

Evaluating the two types of processes, one continuous and one batch, when they used pareto analysis to plot the data one important fact became very clear: While the process incident numbers were almost even, 99.5 percent of the dollars lost to the deflagration events were burning up in the continuous process.

"When we started looking closely at the continuous process, we realized that what was happening was not a dust explosion at all. It was actually a gas deflagration.”

They reached this conclusion after testing revealed that the processor operated with a deficient oxygen atmosphere for an explosion. The really high-energy incidents were occurring after shutdown, when the internal oxygen level in the processor returned to normal. They tried a number of fixes, and even changed the processor sequence, but the solution proved elusive.

"NFPA 69 presents five options,” said McIntosh. “You can build the process strong enough to contain the explosion, but we couldn’t do that. You can eliminate the oxygen, but that was impossible since it was a process heater that needed oxygen. Third, you take away the fuel. Since the combustible gasses were actually coming from the commodity we were processing, that wasn’t possible. We looked at active suppression, but it's a food grade product so we can't inject chemicals. The only option left was venting."

However, limitations on venting also presented problems. Unable to vent to a non-accessible area outdoors or an area where they could effectively restrict access, and faced with ducting limitations based on distance and the amount of venting they needed to provide, he decided to explore the Q-Rohr application.

"We were in no man's land. There just wasn’t a way to navigate through the NFPA codes that said the Q-Rohr was OK to use since it was only specified for dust explosions as spelled out in the German standards. My first question was: ‘Will the Rembe Q-Rohr work with a combustible gas?’”

“Since the device was installed we’ve had one incident," he concluded. "We were down a fraction of the time compared to the original incident, which shut us down for a number of weeks. There was no damage to the equipment, and the majority of the downtime, less than two days, was simply to verify it was OK to start the equipment back up. It met our expectation...to limit or even prevent the total scope of the damage."

According to Cvetas, Procter & Gamble’s situation is not uncommon, adding that every company CEO he speaks with recognizes that they’ve been exposed to a near-disaster at some point. In the past, many have taken action using available technology to protect their facilities. Unfortunately, active suppression technology was the only option for many years. More expensive to implement and maintain than passive technologies like Q-Rohr, it is also highly intrusive to day-to-day operations when it reacts.

He points out that purely active systems will sometimes trigger a response even when you don't have an accident, and that there are plenty of companies that have spent a lot of money cleaning up a process after the system was set off because of an upset in the process condition instead of an accident.

Cvetas also relates one experience with an eventual client as a demonstration of the ultimate value of explosion protection systems: While visiting the prospective client, his team walked the plant with a group of engineers and managers, discussed what needed to be protected, and when they concluded the tour one engineer asked for a ballpark figure. The engineer looked at the number and exclaimed, ‘That's more than the whole process cost to put in!’ At which his boss pointed out: ‘We're not just protecting the equipment or the people in the plant, were also protecting the million dollars of revenue that the process generates every day.’

"Everyone that we've provided consulting services and equipment installations to are operating industrial or material processes that produce significant revenue streams, from a quarter-million to several million dollars a day,” said Cvetas. “If they have an explosion, with an active system they're often down for days. Processes without any protection can take a facility down for weeks or months.”

With the knowledge that more options equal better solutions when the options are thoughtfully and judiciously applied, he emphasizes that the best explosion protection system is one that blends the appropriate amount of the latest active and passive technologies, with the resulting system as non-intrusive to process operations as is feasible given the nature of the application.

“What explosion protection systems really provide is insurance,” Cvetas concluded. “They give companies the peace of mind that they are operating their plants safely, not only preventing potential loss of life but also protecting their capital goods and the valuable process revenue that they depend upon.”

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