2019 July/August Biomass Magazine

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July/August 2019


HEAT Burgess Biopower’s Mission to Utilize Wasted Thermal Energy PAGE 12


Improving Boiler Reliability, Decreasing Downtime PAGE 24


Tire Giant Swaps Oil Boilers With Biomass PAGE 18


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Workhorses of the Power Industry By Anna Simet



06 Pressure Builds on US EPA to Process e-RINs

Burgess Biopower is a 75-MW biomass power plant located in Berlin, New Hampshire, on the Androscoggin River. Formerly a shuttered pulp mill, the converted plant is striving to implement waste heat utilization projects with new partners.

By Bob Cleaves

08 The Impact of Government Regulations By John Ackerly




12 PROJECT DEVELOPMENT The Value in Capturing Waste Heat

Burgess Biopower is partnering to recover and utilize its ample wasted thermal energy. By Anna Simet

18 PROCESS Low-Carbon Cure

A Sri Lanka-based tire factory is converting from fuel oil boilers to biomass for steam generation in its tire-curing process. By Ron Kotrba



24 MAINTENANCE AND REPAIR High-Efficiency Shutdowns: Improving Boiler Reliability and Increasing Uptime

Regular inspections of boilers and other plant components can improve safety, reliability and value, while reducing failures and unplanned downtime. By Rebecca Knecht

26 SAFETY Self-Heating Hazards of Biomass Material

As storage requirements increase with the expanding biomass energy industry, so do self-heating safety risks. By Vahid Ebadat

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Biomass Magazine: (USPS No. 5336) July/August 2019, Vol. 13, Issue 4. Biomass Magazine is published bi-monthly by BBI International. Principal Office: 308 Second Ave. N., Suite 304, Grand Forks, ND 58203. Periodicals Postage Paid at Grand Forks, North Dakota and additional mailing offices. POSTMASTER: Send address changes to Biomass Magazine/Subscriptions, 308 Second Ave. N., Suite 304, Grand Forks, North Dakota 58203.



Workhorses of the Power Industry



It is widely believed the first steam boiler was invented in 1867 by American inventors George Babcock and Steven Wilcox. Fast-forward to today, and the same company founded by the duo over 150 years ago is still manufacturing and installing boilers for a vast array of applications, all across the globe. One particular instance is at Burgess Biopower, a 75-MW power plant featured on the cover of this issue, and the topic of my page-12 feature, “Capturing the Value of Waste Heat.” In fact, B&W installed the original boiler in 1993, when it was a Fraser pulp mill. Decades later when the facility was purchased by its current owner, the firm was hired to perform retrofits that enabled the facility to use wood chips as fuel to produce electricity and steam. All along, the plan had been to partner with others to utilize the plant’s waste heat. Now, that vision is nearly a reality, via projects with a large-scale greenhouse, and the plant’s home town of Berlin, New Hampshire. More on our theme of boilers, turbines and generators, Senior Editor Ron Kotrba had the opportunity to discuss Sweden-based Trelleborg Wheel System’s transition from fuel oil to biomass with company President Paolo Pompei. The company is utilizing India-based Thermax Ltd.’s automated Combipac steam boilers, which will not only cut emissions drastically, but save energy and protect the soil, according to Pompei. He reiterated the company’s motivation is mostly environmental, declining to discuss cost or any potential fuel savings. Instead, he told Kotrba, “This is a key milestone project in achieving a reduction in the carbon footprint within the whole organization—something where we have put huge investment.” Further into this month’s issue, in our page-24 contribution on high-efficiency shutdowns by Evergreen Engineering’s Rebecca Knecht, she walks readers through the necessary steps to ensure effective and efficient outages, which include routine inspections of boilers, pressure vessels, piping, tanks and other plant components. No matter the preparation, however, Knecht points out that every boiler outage will have discovery, or unforeseen repair work identified during inspections. She emphasizes that no matter the caliber of the discover work, it should be documented. That way, it will help track future costs, highlight any failure patterns and identify areas that may need additional focus on preventative maintenance. Rounding out our roster of feature and contribution articles, on page 26, we’ve included a selfheating hazards piece by Vahid Ebadat, CEO of Stonehouse Process Safety Inc. While not exactly aligning with the theme of this edition, it is certainly relevant. As Ebadat points out, as the industry expands with new installations, conversions and retrofits, now is the time for the industry to understand and learn how to mitigate the inherent risks that come with utilization of biomass material.




EDITOR Anna Simet asimet@bbiinternational.com SENIOR EDITOR Ron Kotrba rkotrba@bbiinternational.com ONLINE NEWS EDITOR Erin Voegele evoegele@bbiinternational.com COPY EDITOR Jan Tellmann jtellmann@bbiinternational.com


ART DIRECTOR Jaci Satterlund jsatterlund@bbiinternational.com GRAPHIC DESIGNER Raquel Boushee rboushee@bbiinternational.com


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Subscriptions Biomass Magazine is free of charge to everyone with the exception of a shipping and handling charge for anyone outside the United States. To subscribe, visit www.BiomassMagazine.com or you can send your mailing address and payment (checks made out to BBI International) to Biomass Magazine Subscriptions, 308 Second Ave. N., Suite 304, Grand Forks, ND 58203. You can also fax a subscription form to 701-746-5367. Back Issues & Reprints Select back issues are available for $3.95 each, plus shipping. Article reprints are also available for a fee. For more information, contact us at 701-746-8385 or service@ bbiinternational.com. Advertising Biomass Magazine provides a specific topic delivered to a highly targeted audience. We are committed to editorial excellence and high-quality print production. To find out more about Biomass Magazine advertising opportunities, please contact us at 701-746-8385 or service@bbiinternational.com. Letters to the Editor We welcome letters to the editor. Send to Biomass Magazine Letters to the Editor, 308 2nd Ave. N., Suite 304, Grand Forks, ND 58203 or email to asimet@bbiinternational.com. Please include your name, address and phone number. Letters may be edited for clarity and/or space.


Pressure Builds on US EPA to Process e-RINs BY BOB CLEAVES

Across from the White House tucked in behind the Renwick Gallery is a little-known federal office that goes by the name OIRA, or Office of Information and Regulatory Affairs. Created in 1980, OIRA (pronounced “of-eye-ruh”) is tasked with ensuring that significant regulations are carefully reviewed for their impacts on business, and to make sure that all federal agency viewpoints are coordinated. In effect, OIRA serves as the gatekeeper before draft regulations become public. As you can imagine, OIRA plays a critical role in the development of annual volume obligations under the Renewable Fuel Standard, including the release of the proposed 2020 renewable volume obligation (which will likely be released before the publishing of this column). For that reason, the RFS Power Coalition was keenly interested in meeting with OIRA as part of its public outreach process, to share a few thoughts about electric renewable identification numbers, or e-RINs. When we were given a time slot earlier this month, we jumped at the opportunity. Though not a secretive affair—documents we shared are available online—there is no transcript of the meeting, and OIRA was in listening mode only, sort of like talking to your Amazon Echo, but hearing nothing back. Since “information is the best disinfectant,” borrowing from the words of Justice Louis Brandeis, we thought we would reconstruct our dialogue with OIRA, albeit in an abbreviated fashion with some editorial license, to give readers a flavor for the conversation. OIRA: “Thanks for coming in. You have 30 minutes.” Us: “Thanks for the opportunity to meet. The wasteto-energy industry provides important infrastructure across the country for the management of wastes, and enhances local communities while providing renewable, domestically sourced, carbon-friendly electricity. The biogas industry complements rural America by allowing farms to cost-effectively and sustainably convert waste to energy. And the biomass industry, like other technologies, creates baseload power but without the benefit of federal subsidies that other technologies like solar and wind receive.” OIRA: “Thanks for that background. That’s helpful.” Us: “Let’s get down to brass tacks. We aren’t seeking a shift in policy or asking for a change in law. For 11 years, the EPA has ignored electricity in the RFS. Congress authorized it in 2007. EPA approved it in 2010. Biogas-to-power became an approved pathway in 2014. This is a simple case of an agency refusing to undertake what we lawyers call a nondiscretionary duty. The effects of EPA’s failure to act are significant. All of our industries are experiencing closures. It’s not up to EPA to pick and choose which transportation fuels to make part of the RVO. Congress already made that decision.” 6 BIOMASS MAGAZINE | JULY/AUGUST 2019

OIRA: (Listening and taking notes.) Us: “So, why should OIRA care? For a host of reasons. First, we have an action before the D.C. Circuit, challenging EPA’s failure to include e-RINs in the 2019 RVO. Unless you know something we don’t, the 2020 RVO will also be silent on e-RINs, and EPA will again be promulgating an unlawful rule. And second, if OIRA authorizes this rule and allows it to go forward, it runs the risk of the court reversing the rule and retroactively imposing further obligations on RIN buyers to make up for the volume not counted in the rule. This will send the RFS program into complete disarray and create extreme market turmoil.” OIRA: “You have a few minutes until our next meeting.” Us: “And here’s the last reason OIRA should care—under the RFS, EPA has the statutory duty to consult the U.S. Energy Information Administration when promulgating the RVO (the statutes uses these words: “in coordination with the Secretary of Energy and the Secretary of Agriculture”). We already know how USDA feels about e-RINs. They support them. So what about DOE? Well, to the best of our knowledge, EPA never consulted DOE on the amount of electricity used for transportation. But we have. And this is what we learned in the chart nearby. So please, send this rule back to EPA and ask them to consult the same DOE we did, and include e-RINs in the 2020 RVO. Eleven years, 168 days, and 15 hours, roughly, is quite long enough.” OIRA: “Thanks for coming in.” That was it, the entire 30-minute meeting. As you can see, we did not get much in the way of feedback from our friends at OIRA. However, we got the chance to make our case, and I believe it’s a strong one. Around the same time as our meeting, a letter from a bipartisan group of 21 members of Congress was sent to EPA Administrator Andrew Wheeler, advocating for the immediate processing of the electric pathway. A few days later, a bipartisan letter from nine Senators went to Wheeler, asking for a status update after President Trump signed an appropriations bill in February. The letter “strongly encouraged” the EPA to process electric pathway applications within 90 days. We will continue pursuing our case until we are successful. If your company is interested in getting involved with our RFS Power Coalition, please reach out to us. Authors: Bob Cleaves President, U.S. Biomass Power Association bob@usabiomass.org www.usabiomass.org

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The Imact of Government Regulations BY JOHN ACKERLY

In the April issue of Hearth & Home Magazine, its longtime editor and publisher Richard Wright contemplated why there seems to be a lack of innovation in wood heaters these days. Wright thought the stricter 2020 U.S. EPA regulations were to blame, since companies were forced to spend so much time and money on R&D to meet the new emission limits. This floored me. I had assumed that if companies were required to meet stricter emission regulations, they would have to innovate. But here’s the rub: What defines innovation, and what is just tweaking current designs? To make it more complex, are there tweaks or innovation that make stoves cleaner in the lab, but perform worse for consumer over time? One thing most industry members agree on is that the 1988 EPA emission regulations forced profound and beneficial technological innovation. That is what good regulations should do. Some experts go as far to say that those regulations saved the industry from itself, and gave the technology a new lease on life. Why wouldn’t the second round of EPA regulations, enacted in 2015, have some of the same impact? I believe that the 2015 regulations taking full effect in 2020 will result in innovation, but that much of that innovation will take years to evolve, and we will need to wait and see what holds up in the hands of consumers. Each category— wood stoves, pellet stoves, wood boilers, pellet boilers and wood furnaces—will all see different types of innovation. The best will hopefully be affordable and durable, and is perceived to be a real step forward by consumers. Consumers care more about efficiency than emissions, and they also care about ease of use and convenience. Let’s take the case of pellet stoves. We’re already seeing that the new EPA regulations resulting in far more efficient pellet stoves. Did that take innovation? Or was it just adding more heat exchange? It may be more of the latter, but the bottom line is very positive for consumers. With wood stoves, we are seeing many more companies adding catalysts along with traditional secondary combustion, resulting in “hybrid” stoves. And this is where the jury will remain out for years to come. How will a new class of catalytic stoves hold up? Most experts have pointed to faulty design, where the flame impinges on the catalyst. But the big, untold story here is the erratic and often faulty fabrication of the catalysts themselves. If they don’t hold up, even the best catalytic and hybrid stoves will underperform. And, there are some consumers who just don’t engage the catalyst, even if it’s working well. Wright wrote that “many manufacturers spent over $1 million getting ready for 2020, and they had no time remain-


ing to develop something innovative” for the 2019 season. His assumption seems to be that companies can do one thing or another, but merging innovation with preparing for stricter emission standards is not so easy. Wright may be looking for other types of innovation, outside of the basic performance of a stove. He says, “Innovative products are what drive industries forward.” We couldn’t agree more. In the hearth field, the most innovative products would renew the social license of stoves. It would give not just stove retailers something new to talk about, but also gives mainstream magazines and newspapers something to write about. Our bet was that automated wood stoves would be the innovation that gives society something new to talk about, and drive down emissions in hands of homeowners. These days, all sorts of automation is common, invisible and expected. Not so with wood stoves. Many, if not most, consumers will initially be wary of them, and the goal of designers may be to hide it. We are still bullish on automated stoves, but as Wright noted, companies may still be able to cut emissions from 4.5 grams to 2 grams an hour simply by tweaking existing technology, matched with expert lab technicians who conduct the certification testing. Why innovate if tweaking existing designs can get below 2 grams an hour? Other than automation, the next real wave of innovation will be in test methods—not driving standards below 2 grams an hour. Part of the reason innovation may be stalling is that stove design has become too dependent on outmoded certification test methods, and stove designers are too familiar with how to maximize their numbers from these old test methods. We need new test methods that will give rise to new stove innovation. That method should use cordwood and reflect how stoves are used in homes. The Integrated Duty Cycle methods being developed by NESCAUM (Northeast States for Coordinated Air Use Management) provide much of that innovation needed in our test methods. Within 10 years, all stoves should be required to test with cordwood. By combining test protocol innovation with stove technology innovation, we may produce a new breed of stoves that can propel them into the 21st century. And then, we will all have something new to talk about. Author: John Ackerly President, Alliance for Green Heat jackerly@forgreenheat.org www.forgreenheat.com


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Covanta, Babylon extend partnership Sustainable waste and energy solution company Covanta has extended its partnership with the town of Babylon, New York, for waste management services at the Babylon Resource Recovery Facility in West Babylon, New York. The new agreement continues a three-decade relationship through 2035, and provides the company with new opportunities for increased metals recovery and revenue sharing, while offering the town long-term price certainty for waste disposal. Since 1989, the Covanta-operated facility has been a critical component of the town’s sustainable, integrated waste management system which prioritizes recycling and relies on energy recovery for managing the material that remains. In 30 years of operation, the Babylon Resource Recovery Facility has converted over 6.8 million tons of municipal solid waste into 3.2 million megawatt-hours of energy, recovered approximately 135,000 tons of metal for recycling, and avoided the life cycle generation of 5 million tons of greenhouse gasses as CO2 equivalents.


Untha America appoints new director of global business development Industrial shredding specialist Untha America, based in Hampton, New Hampshire, has appointed Gary Moore director of global Moore business development as the company seeks to grow five-fold over the next three years. Moore has almost three decades of industry experience and has helped bring more than 300 shredding projects to life worldwide, including over 50 in the waste-to-energy sector. Before joining Untha’s European team in 2015, where he has contributed to planned strategic company growth over the past three years, he spent 16 years working alongside another large shredding equipment manufacturer headquartered in the U.S.


CDM Smith appoints new industrial sales director

Signal launches advanced NOx gas analyzers

CDM Smith proudly announces the appointment of Rich Hamilton as sales director for its industrial unit. Hamilton brings more than 25 years of experience in strategy development, sales, marketing, operations, contract Hamilton negotiations, change management and project management, and has received multiple awards for sales and delivery. As sales director for the industrial unit, Hamilton will provide leadership and overall guidance to the CDM Smith sales team, help evaluate markets and assess strategy, and support business development and marketing efforts. Hamilton’s experience has been focused on industrial markets including chemicals, food and beverage, mining, oil and gas, and power utilities. He is a graduate of the U.S. Military Academy at West Point with a degree in engineering. He was captain of mechanized infantry in the U.S. Army for five years, serving in a variety of roles.

Signal Group has announced the latest additions to its advanced series IV gas analyzers. The Quasar instruments employ chemiluminescence detection for Quasar Analyzer the continuous measurement of NOx, nitric oxide, nitrogen dioxide or ammonia in applications such as engine emissions, combustion studies, process monitoring, continuous emissions monitoring systems and gas production. Heated vacuum chemiluminescence is the reference method for monitoring NOx (combined NO and NO2), offering higher sensitivity with minimal quenching effects, and a heated reaction chamber facilitates the processing of hot, wet sample gases without condensation. Signal’s vacuum technology improves the signal to noise ratio, and a fast response time makes it ideal for real-time reporting applications. However, a nonvacuum version is available for trace NOx measurements. Series IV instruments are compatible with 3G, 4G, GPRS, Bluetooth, Wifi and satellite communications; each instrument has its own IP address and runs on Windows software. This provides users with simple, secure access to their analyzers at any time from anywhere.

BIOMASS to ENERGY ProcessBarron is there every step of the way.

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Capturing the Value of

Waste Heat Burgess Biopower is securing unique partners to help the 75-MW plant capitalize on all it has to offer. BY ANNA SIMET

The 75-MW Burgess BioPower plant is located at the site of a former pulp mill in Berlin, New Hampshire. Since it began commercial operations in 2014, it's estimated the biomass power facility injects over $63 million into the New Hampshire economy each year.




hen the idea of converting a shuttered paper mill in Berlin, New Hampshire, to a biomass power plant was first conceived by CS Operations Inc. in 2012, the developer had much more in mind than solely generating electricity from forest residue. Opportunity at the site was ripe, but added-value projects would come much further down the road, after several years of construction, operations and optimization. Fast-forward to today, and that point has finally reached. Being a new, large-scale, solid fuel power generation facility, there were some initial challenges during the ramp-up process, but for the past few years, the plant has been running at a 90plus percent capacity factor. “That’s pretty high for a solid-fuel power plant,” says Dammon Frecker, executive vice president at CS Operations. “It’s very efficient because of the boiler’s bubbling fluidized bed design.” Babcock & Wilcox was awarded the engineering, procurement and construction contract for the conversion project, appropriate as the company had installed the existing boiler in 1993, replacing two aging black liquor recovery boilers. Other updates needed to transform Burgess BioPower into a fully functioning biomass power facility included a new turbine/generator, cooling towers, electrical switchgear with associated supporting auxiliaries, state-of-the-art air quality control systems, and a new wood yard. As for fuel, the plant currently uses about 800,000 tons of forest residue a year, according to Frecker. “About 60 percent comes from New Hampshire, 20 percent from Maine, and the rest from other neighboring states and Canada,” he says. The site that Burgess sits on is a 65-acre parcel of land, half of which housed the prior pulp mill when it was in operation. “Between the wood fuel storage area and the plant operations itself, we consume a little over one-third of that total area,” Frecker says. “The site was originally laid out with the notion we could attract other economic development that has synergies with Burgess Biopower’s operations. There is a significant portion occupied by a former warehouse that serviced the pulp mill when it was in operation—which we don’t utilize—and there is a fairly large flat portion of land near the warehouse that makes a good spot for another commercial development.” Excess space aside, another factor in finding the right partners is the potential utilization of the plant’s copious amount of waste heat, which is currently released via the plant’s cooling tower. With these two components in mind, Burgess began spreading the word that it was interested in partnering with companies that might be a good fit for the location, and was introduced to a developer with intentions of building a greenhouse. “They will grow baby greens to be sold in regional produce markets,” Frecker explains. “After conversations ensued, feasibility and market studies performed, and conceptual layouts with high-level costing, we determined the project has legs and could make sense. Now, now we’re doing further design and engineering to bring the project to a permanent stage.” BIOMASSMAGAZINE.COM 13

With a compact downtown, snow removal is cumbersome for the city of Berlin, and currently done with plows and snowblowers. Snow is then hauled in trucks to a snow dump miles away. PHOTO: JIM WHEELER

The state-of-the-art, $25 million hydroponic greenhouse will use both on-site acreage and waste heat for its operations. The project recently scored a $500,000 grant from the New Hampshire Public Utilities Commission, funds derived from the state’s renewable energy fund. “What we’re looking to do is recycle the water used to cool our steam condenser—about 50,000 gallons

per minute that recirculates through the condenser and comes out at about 90 degrees Fahrenheit,� Frecker explains. “It’s low-grade heat, but there are lots of Btus there because of the high volume of water that’s recirculated. We’ll tie that extraction point into our cooling water loop, and build a little pump house that can send it across the site to the greenhouse location. When the water gets

there, we’ll utilize two centrifugal heat pumps to pick up the temperature above that 90 degree number that it comes out—somewhere around 120 or 140 degrees, where it’s much more useful in a space heating application.� Detailed design and engineering is underway, and the partners hope to complete that stage within the next couple of months. Then, they will file a site plan approval application with the city of Berlin. “We hope to get through permitting by the end of Q3 or Q4 of this year, and enter into a final agreement with the greenhouse company,� Frecker says. “Once all that’s in place, we hope to get into construction as soon as the weather will allow, which will take six to eight months. We could be in commercial operating in the summer of next year, or early fall.� Frecker says codevelopment has been a goal since Burgess began the conversion process. “We’re really excited about bringing this to fruition, as well as the environmental sustainability aspects of the project.� The thermal recovery project will avoid burning over half a million gallons of oil per year in a boiler to heat the greenhouse, help the state reach its thermal renewable energy generation goals, and substantially reduce water according to Frecker. “Because that water will not

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PROJECT DEVELOPMENT¦ be evaporating out of the cooling tower and the heat will be rejected to the greenhouse, we’ll reduce water consumption by about 6 million gallons of year.” While the greenhouse project is substantial, it will only utilize 10 percent of the total heat currently rejected out of the cooling tower, leaving plenty of room for additional projects—such as a sidewalk and street snow melting system for the city of Berlin. “We’ve been working with the city for over a year to help them evaluate the technical and economic feasibility of using some of our waste heat to heat a portion of the city’s downtown streets and sidewalks,” Frecker adds. “There is still plenty of heat available to do that, and it would have a similar energy demand as the greenhouse, so between the two projects, that will only account for 20 percent of our waste heat.” The city has found much value in Burgess since the plant came online, and City Manager Jim Wheeler says its impact on the community has been tremendous.

Another Potential Partner

“We’ve had the direct impact of jobs and tax revenue from the facility, and it’s also had an indirect ripple effect well beyond its fenceline—it creates jobs in the forest industry, a traditional industry in this area,” Wheeler tells Biomass Magazine. “The forest industry suffered a big blow

when the pulp mill closed, but Burgess has really kept it alive.” Through tax revenue the city has received from Burgess, it has been able to directly fund infrastructure projects—a recent example being a major road reconstruction project. “It was about three and a half miles of primary artery through the city, with landscaping and beautification,” Wheeler says. “This has been a project helping us convert our economy, which is diversified, and includes a tourist economy—we’re in a beautiful area of northern New Hampshire.” Wheeler, who has an engineering background, says he can see the biomass plant from his office window, across the river. He has known about the tremendous amount of thermal energy sent through the cooling tower, and that it could be harnessed for beneficial uses. “We investigated those uses on a municipal level, and came across Holland, Michigan, a community of about 30,000. It turns out that they have been doing what we want to do since the 1980s, and extremely successfully.” The Holland BPW snowmelt system utilizes waste heat from power generation, to heat water that is circulated through 190 miles of tubing laid beneath the pavement and sidewalks, and back to the Holland BPW power plant. The system pumps over 4,700 gallons of water per minute

Boiler & Turbine Super Move When Burgess Biopower’s electrical generator and turbine arrived by ship in Searsports, Maine, two transport permits were required to haul them the 185 miles to Berlin, at a max speed of 25 miles per hour. Each load was carried on a 74-wheel, 19-axle transporter that was 228 feet long, and weighed approximately 255 tons, according to the New Hampshire Department of Transportation. The circulating fluidized bed boiler is capable of firing whole tree chips at a minimum moisture content of 35 percent, and a design moisture content of up to 50 percent. The boiler is equipped with four No. 2 distillate oil -fired burners for use during startup. The steam turbine generator is designed for a steam inlet pressure of 850 psig and a steam inlet temperature of 900 degrees, with a maximum capacity of 66 MW.



The snowmelt and district heating system in development by the city of Berlin and Burgess Biopower would service about 7 acres. PHOTO: CITY OF BERLIN/WILSON ENGINEERING

Evaluating Economic Impacts A study completed by PolEcon Research and released by Advance NH study in 2017 showed: • Annual impact of Burgess BioPower in New Hampshire during 2016 was 221 jobs, $13.9 million in labor income, and $63.4 million in output of goods and services. • In addition to 27 direct jobs, Burgess BioPower supported 184 jobs in Coos County, of which 43 percent were in the logging and sawmill industry; in total, the jobs in Coos County accounted for $11.5 million in labor income. • Without the plant’s payments-inlieu-of-taxes to the city of Berlin—which totaled $1.15 million in fiscal year (FY) 2019—Berlin’s tax rate would have increased by nearly 5 percent. Berlin taxpayers (median home value of $88,400) saved approximately $168 per year in property taxes, with savings expected to reach $300 per year in FY 2019. 16 BIOMASS MAGAZINE | JULY/AUGUST 2019

at 95 degrees, and can melt about one inch of snow per hour at 20 degrees with winds of 10 mph, according to the city. It has been expanded several times over the past two decades, and provides heat to approximately 600,000 square feet of heated sidewalks and streets. Berlin wants to emulate what Holland is doing. “Not everybody can do this,” Wheeler points out. “First, you have to have a power plant near down town.” A location would also need to get a lot of snow for the financials to work out—i.e., significant expenditures on snow removal, salting, plowing, etc. Holland receives approximately 75 inches of snow each year, and though last year was about 25 percent above average, Berlin sees about 100 inches on average. “We’re different than the southern part of New Hampshire— higher in elevation, further north, and we’re up in the White Mountains. The conditions up here in the winter time can be tough.” With a compact downtown, snow removal is cumbersome. “We do it now with municipal forces, the old-fash-

ioned way,” Wheeler says. “We plow it, we snow blow it, we fill dump trucks and haul it miles away to a snow dump. We’re spending money to do it, yet it’s still icy and slippery. When we looked at Holland we thought, what a perfect fit for us.” The city commissioned a feasibility study with positive results, and is now looking at the next stage of development. “We now know it’s feasible,” Wheeler says. “But it’s much bigger than just a snow melting system—it’s a down town reconstruction project. The city is at a point where it needs that, as our infrastructure is aging, and it’s time to renew it. So the time to do that would be when we’re tearing up our streets and sidewalks.” A secondary project piece that the city is evaluating is sizing the system to not only serve the snow melting component, but some district heating. “We have a lot of buildings down town and adjacent to where these main transmission lines will be, and they could benefit from the heat,” Wheeler says. “So we’d like to use that as an economic development tool as well.” Ideally, the system would service about 7 acres. “It does come with a hefty capital cost, but we’ll save money each year,” Wheeler says. According to the feasibility study performed by Wilson Engineering, the project would cost around $8.3 million for all components (not including the downtown reconstruction project with streetscape improvements, which will cost around $4.5 million, according to Wheeler). The city currently spends around $117,000 on plowing and snow removal each year, and will experience similar annual savings. And, Wheeler points out, that number doesn’t consider the potential generation of thermal renewable energy credits, and the additional economic benefits. “One thing we know Holland experiences, and that we believe we’ll get from it, too, is economic development that is really hard to quantify,” he says. “This past winter, I took pictures of Main Street almost every day, and it was eye-opening to pay attention to. It’s

Near the White Mountains, Berlin, New Hampshire, receives over 100 inches of snow annually, on average. The city currently spends approximately $117,000 a year on snow removal, money that would be saved if a snow melt project with its neighbor across the river, Burgess Biopower, is implemented. PHOTO: JIM WHEELER

generally always icy, has snow on it, and it’s a deterrent to activity downtown that lasts for six months.” Alleviating that issue would likely attract more people down town during winter months. “In Holland, it was unexpected, but people from surrounding communities would come in—for example, buses of elderly to walk and get exercise. We would love to be that. For our downtown businesses, six months of the operating season is affected by snow. With a melt system, all of that goes away.” Soon, the city will apply for federal funds to assist with project costs, but is determining the best path forward. “We’re looking at how we can smartly apply—for construction dollars or planning dollars, and we’ll figure out what makes the most sense to apply for.” In the meantime, Wheeler remains passionate about the project, and reiterates the impact Burgess has made on the city and surrounding community. “Burgess has been a great partner,” he adds. “They love the idea, and we support each other.” Author: Anna Simet Editor, Biomass Magazine 701-738-4961 asimet@bbiinternational.com


By switching from fuel oil to biomass, Trelleborg Wheel Systems will annually eliminate between 10,000 and 15,000 tons of carbon emissions currently spewing into the atmosphere from its single Sri Lanka-based tire factory. This one division of Trelleborg Group has numerous factories on four continents at which it may replicate the effort. PHOTO: TRELLEBORG GROUP


ike many components of the energy-intensive modes of transportation on which people rely in pursuit of commerce, daily living and leisure, tires have become a subject of focus to reduce energy consumption and, as a result, greenhouse gas emissions. Proper inflation and low rolling resistance tires are the most common ways people know to help the environment with respect to their tires, but as they drive down the street or farm the land in cars or tractors running on etha-

nol or biodiesel, sitting on seats made of soy polymers or bioplastics with properly inflated tires, do they ever consider the energy consumed to manufacture those tires? Companies such as Trelleborg Group seek to spark this curiosity in consumers. Trelleborg Group is a Sweden-based multinational manufacturer of engineered polymer solutions. The company has more than 24,000 employees in 51 countries. Trelleborg Wheel Systems, part of Trelleborg Group, is a leading


global supplier of tires and complete wheels for agricultural and forestry machines, materials handling, construction vehicles, motorcycles, bicycles and other specialty segments. It offers highly specialized solutions to create added value for customers, and it partners with leading original equipment manufacturers (OEMs). Trelleborg Wheel Systems’ manufacturing facilities can be found on four continents in the countries of Italy, Latvia, the Czech Republic, Serbia, Slovenia, Sweden, China, Sri Lanka, the




A Sri Lanka-based tire factory switches from fuel oil to biomass for steam generation in the tire-curing process. BY RON KOTRBA


U.S. and, after the 2015 acquisition of Standard Tyres Group, Brazil. In late April, Trelleborg Wheel Systems announced a full reengineering of

its Sri Lanka facility’s steam production process by installing an advanced biomass boiler. The company says this major investment will not only reduce the plant’s environmental footprint, but it will also improve production efficiency. The Trelleborg facility in Sri Lanka is located in Makola, close to the capital city of Colombo, and employs more than 850 people. The manufacturing facility produces solid tires for the material handling and port industries, and pneumatic tires for agricultural applications.

Steam production is essential to the tire-curing process. “Tire curing is the process of applying pressure to the green tire in a mold in order to give its final shape,” Paolo Pompei, president of Trelleborg Wheel Systems, tells Biomass Magazine. “Steam curing is the method used to heat the molds to then stimulate a chemical reaction between the rubber compounds and other materials.” Trelleborg’s Sri Lankan tire factory has traditionally used petroleum-based fuel oil for steam generation. “The Sri BIOMASSMAGAZINE.COM 19


Thermax Combipac

The Thermax-made Combipac steam boiler installed at Trelleborg Wheel Systems’ Sri Lanka tire factory is fully automated and entirely controlled by a supervisory control and data acquisition (SCADA) system with online emission monitoring capability. PHOTO: TRELLEBORG GROUP

Lanka tire manufacturing facility consumed a large quantum of furnace oil—3.5 million liters per year producing more than 11,000 tons of CO2—in the traditional tire manufacturing process,” Pompei says. “The switch from fossil fuels to biofuels was a much-needed step change in the energy footprint. With the introduction of the biomass system, the carbon footprint will be reduced significantly by 90 percent.”

Pompei says Trelleborg constantly invests in reducing its carbon footprint. “It’s in line with Trelleborg’s Blue Dimension strategic initiatives,” he says. “At Trelleborg, we believe that the benefits of our solutions stretch beyond functionality and business performance. They reduce environmental impact by saving energy, cutting emissions and protecting the soil. This is what we call ‘Blue Dimensions-Solutions for Better Sustainability.’ ”




The biomass boiler being installed at Trelleborg Wheel Systems’ tire factory in Sri Lanka is manufactured by India-based Thermax Ltd. “It is a custom-made, fully automated Combipac steam boiler,” Pompei says. In Trelleborg’s April announcement, the company referred to the biomass boiler as “advanced.” When asked what makes it advanced, Pompei says, “The boiler is designed for ‘no man’ operation with a higher degree of automation. It consists of an automated, moving floor along with a conveyer belt system, which manages the fuel feeding of the boiler. The furnace chamber is designed as per the reciprocating grate,” a Lambiyan design, he says, which is fully controlled by a supervisory control and data acquisition (SCADA) system with online emission monitoring capability. Added features, according to Pompei, include an economizer, or heat recovery system, an electrostatic precipitator for particulate control and a fully automated ash-handling system. “The model delivered to Trelleborg is a Combipac 12 TPH boiler with a reciprocating grate combustor,” says Rakesh Tripathi, the global head of Thermax’s heating business. “It is one of the most popular models of Thermax. It uses advanced combustion techniques

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Growing toward a greener, cleaner future. (YHU\ \HDU PLOOLRQV RI WRQV RI LQGXVWULDO ZDVWH DUH WXUQHG LQWR PLOOLRQV RI GROODUV RI UHXVDEOH PDWHULDOV &30 DQG 'L 3L 6\VWHPV KHOS PDNH WKDW KDSSHQ The Thermax Combipac 12 TPH biomass boiler installed at Trelleborg Wheel Systems’ tire factory in Sri Lanka is capable of generating 12,000 kilograms an hour (kg/hour) of steam from consumption of 2,700 kg/hour of rubber wood chips. PHOTO: THERMAX LTD.

resulting in a highly efficient and reliable operation to generate the process steam.� Tripathi says this was a turnkey installation, whereby concept to commissioning is carried out by Thermax. “Thermax is a pioneer in the boiler industry in the South Asian region,� Tripathi says. “Thermax introduced its first biomass boiler for heating applications in the 1980s. The biomass journey started with the introduction of smallsized boilers for process houses. Initial fuels were wood logs, wood chips and rice husk, which are abundantly available in South Asian markets.� Tripathi tells Biomass Magazine that Thermax is committed to providing a cleaner environment for future generations and has continuously worked on improving and introducing better combustion technologies in the markets in which it operates. “Consequently,� Tripathi says, “Thermax has been successful in providing solutions for combustion of more than 150 types of biomass fuels.� According to Thermax’s data sheet on its Combipac multisolid fuel-fired hybrid steam boilers, the system “is a hybrid smoke and water tube design boiler with the combustor based on the principle of fluidized bed combustion. The fuel bed is fluidized by the injection of air from the bottom of the bed,

through a set of air nozzles, using a forced-draft fan. This produces a fuel bed resembling a boiling fluid, which helps achieve uniform mixing and efficient combustion.� Important features of the Combipac steam boiler, according to the boilermaker, include its suitability for burning fine particles; the controlled bed temperature; operation flexibility; rapid response to load; maximum unburnt losses; low excess air required and, hence, higher efficiency; fully automatic operation; uniform heat flux ensuring longer refractory life; specially designed air nozzles for optimum performance; and the ability to handle high moisture, up to 35 percent in coal. Tripathi says the boiler installed at the tire factory in Sri Lanka is capable of handling highmoisture rubber wood chips, Trelleborg’s feedstock of choice. The fuel feeding system offers the flexibility of firing a wide variety of solid fuels. Thermax’s Combipac boilers are equipped with both under-bed and over-bed feeding systems. The underbed feeding system, which consists of a rotary feeder and a booster fan, is appropriate for fuels such as rice husks and various types of coal. The over-bed feeding system is fed by a screw feeder and is suitable for biomass such as






¦PROCESS paddy husks, wood pellets and palm kernel shells, as well as coal. T h e membrane panel assembly of the Combipac steam boiler features Tripathi a D-type membrane panel for a controlled bed temperature and to better achieve water circulation. The design also reduces stress concentration on the shell tube plate. Thermax says the Dtype membrane panel provides effective radiative heat transfer due to the optimum distance between the membrane panel assembly and the bed. The Combipac membrane panel is also equipped with integrated in-bed tubes to recover heat from the radiation zone and maintain uniform bed temperature. Important features of the in-bed tubes include the fact that all bends are placed outside the fuel bed zone, which helps eliminate erosion levels. Due to a higher pitch, a lower air and particle velocity is achieved between tubes, which also aids in ensuring a reduction in erosion levels. Furthermore, tube overheating is eliminated thanks to the design, allowing for a very high circulation ratio and water velocity. The boiler shell assembly, according to Thermax, features an efficient and dependable convective pass design with optimally sized diameter tubes, no flue gas turning in the convective bank and a reduction in tube and tube-plate erosion. The company also says the shell assembly design provides high-quality steam and better load response thanks to a higher steam/water interface area and higher freeboard. The wire coil inserts provide improved flue gas turbulence and velocity and improved heat transfer performance. The simple layout of the shell assembly, according to Thermax, allows for easy cleaning via hinged-door smoke chambers.

Ultimately, Thermax says its Combipac line of boilers improves overall combustion efficiency and provides better response to steam load resulting from higher turbulence levels, better residence time, low excess air and uniform distribution of air and fuel.

Full Steam Ahead

Pompei wouldn’t disclose how much the conversion project is costing the tire manufacturer. When asked of the price tag, Pompei simply says, “This is a key milestone project in achieving a reduction in the carbon footprint within the whole organization—something where we have put huge investment.” Pompei says energy is a “significant element” in manufacturing costs, and the new boiler and wood chips as fuel will bring a “significant reduction” to the cost of steam generation. “Further,” he says, “entering into fixed-term contracts with new raw material suppliers would help us reduce possible market fluctuations.” The biomass boiler will use nearly 2,700 kilograms per hour (kg/hour) of rubber wood chips, according to Tripathi, for generating steam at its full capacity at standard operating conditions. “This is equivalent to 830 liters of diesel firing for same heat delivery,” he says. “Use of biomass in place of fossil fuel such as diesel will result in a reduction of 15,000 tons of CO2 emissions per year.” Tripathi says the boiler is capable of generating 12,000 kg/hour of steam, which is equal to 7.5 MW of effective heat delivered to the process. Biomass delivery will be entirely fulfilled by local producers, Pompei says, “thus shortening the supply chain, further reducing our carbon footprint and supporting the local economy.” Biomass Magazine reached out to Sri Lankan native Lucky Dissanayake, founder of Biomass Group Ltd. and its Sri Lanka-based subsidiary Biomass Supplies, which is developing a supply chain of Gliricidia Sepium—a rapidly growing, short-rotation tree found wild throughout the island nation—based on an outgrower, or contract farming, ba-


sis. Dissanayake says Biomass Supplies is not involved in the supply of rubber wood chips to Trelleborg. She says until very recently, many local industrial companies in Sri Lanka seeking biomass supplies would simply “hire a man with a saw and a van and really didn’t care as to where the biomass came from, which inevitably meant that trees were being cut down within a radius of the factory.” Tragic events this spring, however, changed this, Dissanayake says. This past Easter Sunday, April 21, a series of bombs in churches and hotels killed hundreds of people in Colombo. “The chainsaws and machetes belonging to laborers were confiscated, and many industries are now asking for our biomass supplies,” she tells Biomass Magazine. “So we are doing tests now to determine how best to deliver volumes to industry.” Interestingly, Trelleborg Wheel Systems is not the first tire factory in Sri Lanka to go green with biomass boilers. In January 2017, Global Rubber Industries Pvt. Ltd. broke ground on a new specialty tire factory adjacent to its exiting solid tire manufacturing facility in Colombo. It features solar panels, biomass boilers and recyclable waste management systems. Trelleborg’s biomass conversion project began last year and will be completed by the end of June. Pompei says GRI’s foray into biomass at its Sri Lankan plant did not influence Trelleborg’s decision to switch from fuel oil to biomass. He does, however, say that this project may lead to more like it within the expansive network of Trelleborg factories. “In line with Trelleborg Group’s Blue Dimension approach for better sustainability, these kinds of studies are always a top priority for new ways of exploiting green energy over time,” Pompei says. “This new biomass boiler investment will be a pilot project to be evaluated for the rest of the group.” Author: Ron Kotrba Senior Editor, Biomass Magazine 218-745-8347 rkotrba@bbiinternational.com

Solid Fuel Combustion


HIGH-EFFICIENCY SHUTDOWNS: Improving Boiler Reliability and Increasing Uptime Regular inspections of boilers, pressure vessels, piping, and tanks help reduce the risk of failures, accidents and unplanned downtime. BY REBECCA M. KNECHT


our annual outage comes along only once a year—make the downtime count. Good outage performance ensures equipment critical to the safety or operation of your process remains functioning as it was originally designed. With an efficient and effective outage, all your necessary inspections and repairs can be performed in the minimum time possible. The key to a successful outage begins early, with the process of planning the work. The first phase of planning should be defining the scope of work for the outage, beginning with rounding up all the deferred maintenance items and pending work orders. Define what work is going to be done in-house, and what will be done by outside services. Identify consumables, parts to be ordered, and any long lead-time items. Have a procurement plan in place to get contracts issued as early as possible, to lock in contractors and vendors and ensure you get the resources you need. Another key part of your outage plan should be creation of an accurate cost es-

timate once you know your scope of work and have gathered costs from suppliers, contractors and vendors. Ensure there is sufficient cost coverage for discovery repairs. This is often an underestimated cost item that can make or break a project’s budget. The second planning phase is scheduling the work. Having a detailed, critical path method schedule will define your outage duration and labor loading, and will serve as a way to track job completion and project costs. Remember, the schedule is only as good as the data you give it. The final phase should be a readiness review to determine if you’re ready to perform the outage. Are all jobs identified and planned? Are outside resources ready to perform the work? Is there a logistics plan in place for the site during the work? Are the plant safety plans (lockout-tagout, confined space entry, hot work, etc.) in place and adequate?

Ready, Set, Go

Now that you’ve assembled a solid outage plan, it’s time to execute.

Data gathering and asset sustainability assessments can be the biggest tools in your inventory for increasing overall boiler reliability. There is no better opportunity to get in-depth data than when the equipment is shut down. Unplanned downtime is costly. By investing in inspections and planned repairs during annual outages, you help minimize the risk of being suddenly shut down due to unexpected failures. Thorough, regular visual inspections and nondestructive testing provides a wealth of data that can be used to predict boiler component lifespans, conditions and risk of failures before they occur. Mapping of the boiler pressure parts for material thickness is a simple, effective, and noninvasive way to evaluate the health of pressure parts. Prioritize high-risk boiler systems like generating bank tubes for near drum thinning, soot blower lanes for erosion/corrosion, economizers and feedwater inlets for oxygen pitting and flow-accelerated corrosion. Create a pressure parts periodic inspection program and make it a living docu-

CONTRIBUTION: The claims and statements made in this article belong exclusively to the author(s) and do not necessarily reflect the views of Biomass Magazine or its advertisers. All questions pertaining to this article should be directed to the author(s).



ment—the more data you collect, the more accurate picture of the health of your system. Condition assessments should include a combination of nondestructive testing techniques that target the welds where cracks typically develop and creep off of the header causing it to swell; diameter should be measured at several locations on the header and the outlet nozzle. All major header welds, including the outlet nozzles, torque plates, support lugs, support plate and circumferential girth welds should be examined by magnetic particle testing and liquid penetrant testing. Ultrasonic shear wave or eddy current examination can be performed to locate substrate flaws. Low-temperature header damage is typically caused by corrosion or erosion, while high-temperature failures are generally the result of a finite creep life expectancy, creep fatigue and erosion and corrosion. The most typical steam pipe failure is cracking of attachment welds. These cracks are caused by thermal fatigue, improper support or improper welding. Every boiler outage will have discovery—work that gets identified during inspections, and repairs that need to be done. Large or small, document the discovery work. This will help track additional costs and schedule impacts, and will leave a historical record when planning for future outages. Discovery work can also highlight patterns of failure and areas that may need additional focus on preventative maintenance tasks or future equipment replacement. Active management of outage work is key to keeping on schedule and on budget, two typical markers of outage success. Effective outage management requires good communication with everyone on the outage team, from in-house personnel to outside contractors. Ensuring everyone is engaged in work safety is critical; no outage is a success unless everyone goes home intact.

The Shewhart cycle


Identify Your Problems



Study Results

You’re Not Done Yet


Implement the Best Solution

Even though the outage work is done, there are still some final tasks. Have a lessons learned and after-action review to identify what went well and opportunities for improvement. The closer these are done to the return to service, the better the outcome. Involve the entire project team— not just the internal resources used, but also the engineers, contractors and inspectors. They all have insight into the health of your boiler. Review all inspection reports and findings, as well as discovery items. Compare the mapping of the nondestructive evaluation work and see if there have been changes to the systems from last year. Trending the reports will help identify year-to-year

Test Potential Solutions

changes, and can be used as a predictive analysis tool. Evaluate the inspection recommendations, as these can become the basis of next year’s scope of work. Finally, ensure that everything is documented. In next year’s plan, strive to repeat the successful things, and change the things that didn’t go well. After all, we only learn from our experiences when we reflect on them. Remember that W. Edward Deming had it right with the Shewhart cycle: plando-check-act. Author: Rebecca M. Knecht Construction Manager, Evergreen Engineering rknecht@eeeug.com www.evergreenengineering.com


SELF-HEATING HAZARDS OF BIOMASS MATERIALS The biomass energy sector is growing rapidly, and the number of fires and explosions in the industry is unfortunately growing along with it—it’s time to act. BY VAHID EBADAT


xpansion of the biomass energy sector has driven the need for increased largescale biomass storage capacity to ensure a stable supply of fuel. As storage requirements increase, so do the health and safety risks associated with storage of biomass—in particular, suffocation from off-gassing, fires (sometimes spontaneous) and dust explosions. As a result, the number of reported incidents at biomass facilities is steadily increasing. Online data indicates that although there were 65 reported incidents between 2000 and 2018, they are on the increase—nine incidents occurred in 2017 alone. Furthermore, 55 percent of the reported incidents involved fire, 27.5 percent of which were confirmed self-heating incidents. Additional fire incidents could have been due to self-heating, but not proven. Biomass self-heating is a real problem. In 2017, a huge fire at the Advanced Agro-Power Plant facility occurred in Thailand. Police were quoted saying “a 500-tonne pile of biomass fuels caught fire, apparently because of accumulated heat.’’

Back to Basics

As we should all know by now, most bulk materials and powders that are handled in industry are combustible and under the right (wrong!) conditions can cause fire, flash fire or explosion hazards. A fire hazard will exist if three components are present in one location and at the same time—a combustible particulate solid, an oxidizing atmosphere (typically the oxygen in air), and a credible ignition source. This is commonly referred to as the fire triangle. In the case of dust cloud flash fire (deflagration) hazards, the following conditions must simultaneously

be present: sufficient quantity of combustible dust to propagate a deflagration; oxidizing atmosphere credible suspension mechanism; and credible ignition source. It is noteworthy that the first three conditions are usually expected at some point during any material/dust handling, transfer, processing, dust collection or packaging operations. And, of course, simultaneous existence of a credible ignition source will result in a dust cloud deflagration. If a deflagration occurs in a confined or closed process vessel such as a conveyor or elevator or room/building, pressure that would be sufficient to rupture the confining enclosure, causing a dust explosion, can build. From a regulatory point of view, in a facility where combustible powder/dust fire, deflagration, and explosion hazards exist, NFPA 652 Standard on the Fundamentals of Combustible Dust, 2019 edition, requires that the owner/operator of a facility shall be responsible for meeting the life safety, mission continuity, and mitigation of fire spread and explosions as follows: • Reasonably protect occupants not in the immediate proximity of the ignition from the effects of fire for the time needed to evacuate, relocate, or take refuge. • Reasonably prevent serious injury from flash fires and explosions. • Reasonably protect adjacent properties and the public from the effects of fire, flash fire, or explosion. • Limit damage to levels that ensure the ongoing mission, production, or operating capability of the facility to a degree acceptable to the owner/operator. • Prevent or mitigate fires and explosions that can cause failure of adjacent buildings,

compartments, enclosures, properties, storage, facility’s structural elements, or emergency life safety systems. To meet the above criteria, NFPA 652 requires the owner/operator of the facility to complete the following tasks: • Determine combustibility (fire) and explosibility hazards of materials. • Conduct a dust hazard analysis (DHA), which is a systematic evaluation of potential dust fire, deflagration, and explosion hazards and recommendation of measures for their management. • Manage identified fire, flash fire and explosion hazards. • Establish written safety management systems. A DHA is a systematic evaluation of potential dust fire, deflagration and explosion hazards in a process or facility, and recommendation of measures for their management. This involves identifying locations where combustible powder accumulations or explosible dust cloud atmospheres are or could be present during both normal and foreseeable upset conditions, and identifying potential ignition sources under normal and abnormal operating conditions. For new construction, a DHA must be completed as part of the project. Existing processes and facilities must complete DHAs by Sept. 7, 2020. Additionally, the DHA must be reviewed and updated at least every five years. DHAs must be conducted by someone with proven expertise in hazards associated with handling and processing combustible particulate solids. Depending on the type and nature of the powder and the process, credible ignition

CONTRIBUTION: The claims and statements made in this article belong exclusively to the author(s) and do not necessarily reflect the views of Biomass Magazine or its advertisers. All questions pertaining to this article should be directed to the author(s).


CONTRIBUTION¦ source(s) could include open flames, cutting and welding flames, friction heating or sparks, hot surfaces, sparks from electrical equipment, electrostatic discharges and self-heating. For the biomass sector, there are other relevant industry- or commodity-specific NFPA standards that should also be consulted, depending on the nature of the biomass material. In this article, we have focused only on the requirements of the “top level” standard, NFPA 652.

Self-heating Hazards

When material is bulked in volume, subtle ignition sources associated with heating processes can sometimes present themselves, and perhaps the inherent instability of the material itself. For example, bulk powders or powder layers can self-heat, smolder, and catch fire due to exothermic chemical reaction (exothermic decomposition or exothermic oxidation), or biological processes, which can also generate heat. Barns, hay fields, compost heaps and piles of wood chips have spontaneously caught fire in the past. In this case, it’s water that allows biological processes (respiration) to function and generate heat. Once self-heating begins, there is the possibility of reaching a critical temperature at which the bulk material smolders and continues to accelerate in temperature rise. Bulked material serves as a good thermal insulator, inhibiting cooling and promoting the generation and buildup of heat energy from its core. Self-heating is a complicated phenomenon consisting of both a heat-generating chemical reaction or biological process, and a heat-transfer (heat loss) process. In simple terms, when the rate of heat generation exceeds the rate of heat loss, temperature can quickly rise. If left unimpeded, material self-heating can result in smoldering. Without air, however, combustion cannot take place. In this case, the bulk continues to superheat, but not catch fire, though the off-gasses produced can still provide an asphyxiation risk to operators. When air is introduced, the bulk material can burst into flame. Even raking a pile of smoldering material can achieve this. If dust is then raised, there is a very real risk of dust explosion. In all cases of spontaneous heating, time is an important factor, since some exothermic reactions take a while to get established. It is not unusual to have a fire or explosion days after a hopper or bunker has been filled. Industrial operations that are prone to fires and possibly explosions due to self-heating include powder drying and heating processes.

But heat can inadvertently be applied to materials by the sun, mechanical milling and grinding operations, or when a fugitive powder layer builds up on a hot surface, for example. It is usually when the warm, processed material is allowed to build up as a bulk or layer in various locations within the process equipment, or ultimately, in hoppers, silos, big bags or smaller packages, that the problem becomes evident. Bulk storage of biomass material is the most common scenario for self-heating, and the larger the bulk, the greater the likelihood, with subsequent fire and explosions risk. It should be noted that the onset temperature for self-heating is not an intrinsic property of the bulkier material. Factors such as composition, presence of impurities in the material, geometry, size of the accumulated powder, air/ oxygen availability, and the duration of powder exposure to a given temperature can all affect the onset temperature of self-heating.

Powder Processing, Storage and Transportation

The first step in ensuring safety from selfheating fires and explosions is having a proper understanding of its self-heating properties (including its potential for gas generation). Measurement of exothermic activity normally involves heating a sample under controlled conditions to determine the point at which its temperature starts to increase independently of the external heat source. For laboratory testing to provide usable indication of the hazards, the test sample must be representative of the powder in the process. Additionally, the laboratory tests must reasonably simulate the conditions that the powder experiences during processing and handling, and subsequent storage, packaging and transportation. Often, a screening test is initially performed, during which the test sample temperature is increased at a rate of 1 degree Centigrade per minute. If self-heating is observed at a temperature that is close to the process or storage temperature, or the process cycle is longer than the test period above the process temperature, then an isothermal selfheating test would also be required. • Grewer Oven: Material (test sample) is heated up by means of a hot air stream that permeates through the sample. The surrounding temperature at which the sample temperature starts to rise faster than the inert reference sample is taken as the self-heating onset temperature of the sample. • Isothermal basket test: Performed by heating the powder samples in cubical wire baskets of varying sizes (typically three sizes) in an oven to determine the minimum temperature

at which each sample size self-heats. This test allows one to observe the effect of scale (that is, material size/quantity) on the material’s onset temperature for self-heating more precisely. • Bulk powder test: Used to evaluate selfheating properties of materials in quantities not exceeding 1 ton in situations when it is heated in bulk form. • Aerated powder test: Simulates conditions during heating operations of a material in quantities not exceeding 1 ton, during which a hot air stream flows through the bulking powder. • Powder layer test: Simulates the conditions in which hot air passes above a layer or deposit of material in a dryer. Examples include tray dryers and material deposits on the internal surfaces of all dryer types. For bulk storage of biomass materials, useful screening results are obtained from the above tests, but the basket tests can be used directly to model the effect of hopper/bunker storage volume. Remember, the bigger the storage volume, the lower the temperature at which self-heating will become a problem. Precautions for Avoiding Hazards • Keep the material temperature at a safe margin below the temperature for the onset for self-heating, obtained by appropriate laboratory test methods. • Limit storage time. • Facility and equipment design should avoid ledges, corners, dead zones, etc., where material could inadvertently build up inside process equipment. • Avoid accumulation of hazardous levels of material deposits on the inside surfaces of process equipment. • Measures to avoid other sources of ignition and fire and explosion protection must also be examined through a DHA.


Powders and bulked materials can smolder and catch on fire as a result of self-heating due to both chemical and/or biological processes. Preventing self-heating and subsequent fires and explosions in bulk handling/processing operations requires proper understandingof the thermal instability characteristics of the material through specific and tailored laboratory tests, which should reasonably simulate the conditions experienced by the material during its processing and storage stages. Author: Vahid Ebadat CEO, Stonehouse Process Safety Inc. 609-455-0001 info@stonehousesafety.com