In today’s episode, former coal industry supervisor Blake Nelson shares his years of expertise in alternatives to dust collection, particularly in coal burning applications. He started in the coal utility industry in 1979 and spent several years as an equipment operator, fuel yard foreman and fuel yard supervisor. It was during the latter role that he gained first-hand experience with alternatives to dust collection.
“When we got into dust collecting in ’98 or ’99, when I became supervisor, our coal buyers at corporate had started hearing about PRB Coal, which is in mid-Wyoming,” Blake recalls. “It was cheap- around $3 a ton when we were paying $12 something a ton for Colorado. So they jumped on that and started sending it to us… We realized really quick that while the dust was terrible, it was just 10 times as bad as Colorado coal. It would catch fire really easily out on our stockpile inside the bunkers.”
New Coal Product, Same Safety Problems
The new coal was breaking down at all touch points: during shipping, conveying, and milling, which generated greater quantities of dust. The company installed a dust collector which appeared to work well but it couldn’t help but notice that fires and explosions were occurring at other businesses.
Although Blake’s company never experienced an explosion, there were regular fires, so management reached out to experts at the PRB Coal Users’ Group to help them review their options and identify a better solution.
Then tragedy struck.
“I can’t remember if it was up in Minnesota or Wisconsin, but they’d taken a dust collector out of service to work on it,” Blake says. “They thought they’d cleaned it out. Apparently they didn’t and when they got inside and started welding, it blew up. I cannot remember if there were fatalities. I know people were hurt. That was the last straw for John (the Vice-President) and the rest of the company. So we then called in some outside companies to look at our options. We got our engineers on what it would take to get rid of ours. Since Lawrence only had one dust collector, we decided to make it the test to see how that would work.”
The Challenges of Removing a Dust Collector
Removing a dust collector is a challenging process that involves a lot of compliance issues.
“You’ve got to get permitted by the state. Once you have that permit, you have to run it,” Blake says. “You just can’t decide, Oh, one day we’re not going to run it today and run it tomorrow. When you do that, you have to promise to stay and they come in and check that you can control the dust just as well without the dust collector, as you could with the dust collector.”
The PRB Coal Users’ Group and another company came in to audit the plant. The outcome was a passive dust collection system.
“Basically in the old system,” Blake clarifies. “One conveyor would toss (the coal) onto another conveyor. A lot of times, you would just slam the coal into a piece of iron and it would drop down to the next conveyor. So you really want to force that into a string so that it’s like one continuous conveyor. So you control the air flow inside your conveyors, you control any impact points, etc. Passive dust control is really easy but it’s expensive.”
Water was another technology that the company reviewed.
“Water at one time was a big no,” he says. “Of course, the object was to get everything into that mill as dry and perfect as possible. So we started just spraying water everywhere. Well, water is not really a good dust control. So we brought in, again, some consultants to look at dust suppression. You just apply this chemical at certain transfer areas on the coal handling system. It breaks down the surface of the dust and lets the water soak in.”
They also put washdowns in all of the conveyors.
“(They were) basically lines with nozzles. We made most of them automatic,” Blake says. “The operator can sit in the control room and activate them. They were washing them twice a day.”
Before actually decommissioning the dust collector, the company’s environmental department did several tests. They would take it out of service, run it, and see how the dust suppression system was doing. It was a long process, but eventually the Kansas Department of Health permitted them to decommission the dust collector and run dust suppression.
Conclusion
Blake said that any coal plants with safety concerns about their dust collection system should get the PRB Coal Users’ Group involved and take trips to look at other power plants and source a solution.
“When you see what can happen, it’s very sobering and the loss of one life isn’t worth all the megawatts you can make.”
If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Blake Nelson directly:
Email: [email protected]
If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.
Resources mentioned
The resources mentioned in this episode are listed below.
Dust Safety Science
Combustible Dust Incident Database
Dust Safety Science Podcast
Questions from the Community
Dust Safety Academy
Organizations
PRB Coal Users’ Group
OSHA
Wood Pellet Association of Canada
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DSS110: Alternatives to Dust Collection in Coal Burning Applications With Blake Nelson
