Nestled along the Wisconsin River within the town of Rothschild, Wis., sits Domtar’s paper mill. Built over 100 years ago it serves as one of the region’s largest employers. Considered an area landmark, its presence now is perhaps more marked than ever, with the gradual but seemingly overnight construction of a 50-MW biomass cogeneration plant.
Reaching a skyscraping 265 feet at its highest point, the facility is a new addition to the landscape that residents across the river have been able to watch grow over the past couple of years, a result of years of partnership, permitting and meticulous planning. The bustling construction site—active even through the harsh winter months—is described by Craig Timm, manager of Domtar’s public affairs, as “its own little city.” Having reached peak construction last fall, with around 500 workers on site any given time, the plant is now in the final stretch of construction.
Reflecting on the four-year development process, Domtar and We Energies are enthused—and proud—to share their experiences in working together toward a common goal, but at the same time having completely different backgrounds and objectives.
Project Pieces
Terry Carroll, asset manager for We Energies, says that the idea for the project emerged when the utility was exploring ways to meet the state renewable portfolio standard, which requires 10 percent of electric sales from renewables by 2015. “We had one major wind project at the time and were looking at others, but realized that we needed some diversity, so we started looking at biomass,” Carroll says. “Where would it make the most sense, and who would make a good partner? In terms of procuring biomass, papermaking or lumber product companies are already doing that.”
After We Energies contacted the Pulp and Paper Products Council to gauge potential for a partnership and explain what the company was hoping to do, Domtar responded to the request. From that point on, the two businesses became dedicated partners and began the project, groundbreaking of which occurred in June 2011.
As Domtar already possessed expertise in feedstock procurement, one of the typical key project puzzle pieces was already in place. “We already do business [in sourcing wood fuel], had a small biomass boiler, and a pulping operation that utilizes logs,” says Jim Freiberg, Domtar project manager. “It made sense for us to partner as the fuel procurement agent, and in terms of our financial interests, this would give us the opportunity to manufacture our product at lower costs, utilizing steam from the plant.”
At the time, Domtar was utilizing three aging pieces of steam generating equipment that were destined for replacement in the near future, according to Freiberg, so the opportunity arose in perfect timing for the papermaker.
The power facility will use around 500,000 tons per year of woody biomass material, according to Carroll, which will come ready-to-burn from Domtar’s fuel yard, or will be shredded or chipped off site by suppliers. All fuel will arrive in trucks—about 75 loads per day—and be delivered to one of three receiving stations, where trucks will back into a covered truck tipper and be tilted to release fuel onto the conveyor system. Air in the unloading station is drawn under a vacuum to filter, minimize and suppress airborne dust, and then vented through a 110-foot chimney attached to the truck-unloading baghouse filter. “We have a number of neighbors close by, residences across the street, so all of our biomass handling system is enclosed to keep noise and dust at a minimum,” says Carroll.
Enclosed conveyors transport the fuel to the storage building, also completely enclosed, where about five to seven days’ worth of fuel is stored, according to Carroll. There, an automatic loading system will scalp fuel off the pile, pull it up to another conveyor, and send it into the boiler building. “There we have a modest amount of storage, an hour or less, before it’s fired into the boiler,” he says.
The Metso circulating fluidized bed (CFB) boiler is housed in a 190-foot boiler building, replacing three old boilers—one biomass-fired, and two old gas boilers, and is accompanied by a natural gas auxiliary boiler. “Since the [biomass] boiler undergoes periodic outages a couple of times per year, Domtar needs a backup supply of steam,” Carroll explains. The CFB boiler, coupled with a state-of-the-art emissions control system, will reduce Domtar’s previous emissions by roughly 30 percent. Designed with the U.S. EPA’s Boiler MACT rules in mind, the project’s timing was ideal for planned compliance.
The two-section cooling tower was deployed to eliminate discharge of heated water into the Wisconsin River, and the one selected for the project possesses a plume abatement technology that minimizes water vapor, which is often mistaken for air pollution. At above freezing temperatures, the plume normally will not be visible—if it is, only as a fine mist and will usually dissipate within 30 feet of the top of the tower.
Right now, all major components of the project are in place, so it’s just a matter of connecting and testing them. According to Boldt Construction Project Manager Myron Wagner, getting some of the massive equipment pieces in place required a lot more planning than one might suspect.
Construction Perspective
For jobs requiring movement of extremely heavy equipment, which Wagner says are referred to as “large or major picks,” Boldt uses precision lifting, a complex engineering method used to map out a lift from beginning to end. “The major picks are all engineered, meaning we bring an engineer out with special software, enter in heights and angles and everything is predetermined, right down to the size of chokers and shackles we have to have,” Wagner explains. “One of these picks could be as many as 50 pages of engineering.”
There isn’t room for error with these kinds of lifts, Wagner adds, as some of this equipment is 50 or 100 tons. “You have to get it right the first time; you don’t get a second chance. And on this particular job, we had a couple of interesting picks. For instance, for the steam drum, we had to use two 350-ton cranes at one time.”
Wagner says this specific project has been unique in that it’s essentially been many smaller projects put together. “At any time, we’re working in probably seven or eight different major areas. At the same time, that’s been a little challenging, because we’ve been building a powerhouse on a paper mill site, which are [paper mill sites] generally very tight areas, and this one is no exception.”
Domtar has to ship its product out, typically having 50 to 80 trucks coming in and out each day, and that has to happen without disturbances. “That’s been tough for us,” Wagner admits. “When we start working in a new area, we have to find a new spot for them to park 50 or 80 trailers. So far though, we’ve managed to do that, and we’re proud we haven’t disrupted their business.”
On where the project is currently, hydro testing of the boiler was recently completed, one of the project milestones. “We put water in it and pressurized it to 1.5 times its operating pressure, which in this case was 2,800 psi, and we held that for a length of time to prove there were no leaks, and that was successful,” says Wagner. “The next milestone will be to complete the gas pass—the flu gas that moves through the stacks goes through a number of gyrations to get there—so we can fire this thing up, put fuel through it. Hopefully that’ll happen in early June.”
Initially the plant will be fueled on gas until any kinks are worked out, then biomass will be added. Wagner estimates the entire testing period could last up to two and a half months.
On what the big priority has been as general contractor of the project, Wagner says safety has been No. 1, followed closely by schedule and budget. “We always want everyone here to go home the same way they came,” he adds.
And being a good neighbor has also been important, an aspect that Freiberg and Carroll also highlight.
Good Neighbor
About 90 percent of the labor on site has been hired locally by Boldt, which is based in Appleton, Wis., either within the county or the state. “That’s always a goal of ours, but this local community has been exceptional,” Wagner says. “We have been very fortunate having our craft laborers being very knowledgeable about what they’re doing. “
He adds that We Energies spared no expense to cut down on sound or dust, making sure neither reaches nearby residents or businesses, and that Boldt also tries to source as many building materials locally as possible.
And, of course, on top of job creation, in a town of just under 5,300 people, a big construction project means money in the pockets of local goods and services business owners.
In turn, the good neighbor attitude has been returned by the community. “Members [of the community] have been great,” Timm adds. They, and elected officials on all levels, labor unions, chambers of commerce…they’ve been right along with us during this whole process.”
source: biomassmagazine.com