Before roller debarkers (rotary debarkers) were introduced to the North American paper industry in the late ’90s, the industry lacked good solutions to debark logs in northern climates, where temperatures averaged well below freezing during winter. Dennis Widdifield, a sales engineering with Biomass Engineering & Equipment, worked for Boise Cascade in Ontario at that time, and he was tasked with solving this problem. That he did—and what started as a project for his plant turned into the wide-scale introduction of these machines to North America.
The Need for Better Debarking
In the early ’90s, the Boise Cascade mill at which Dennis worked used a wet debarking process to debark their wood. During this process, millworkers would treat the wood with a water and peel the bark. They would then press and drain the bark and burn it as a fuel.
The problem was that the result was rather toxic. But bark gets wet, it releases oils and resins. So the plant had to treat water used in this process.
To rid themselves of the need to treat this wastewater and to make room for their craft mill, they needed to change their debarking process.
Looking at Debarking Options
Dennis was already familiar with drum debarkers. The company had several in the craft area. But in the winter, it was impossible to remove bark with these machines. Workers would put frozen logs in the drums for two hours at a time, and the drum would do nothing more than polish the bark. The friction, which drum debarkers rely on to debark logs, simply wasn’t enough to peel these logs.
So Dennis and his coworkers looked at other options. Mechanical options of the era included flail debarkers. But flails were hard on wood. They removed too much usable fiber with the bark. They also required constant maintenance. The chains on these machines would wear down fast and break off. Broken chains were bad news if they reached the chippers.
And, of course, most flails were diesel powered, which didn’t help companies sell them in the frigid North. (Diesel gelatinates in cold unless treated.)
Dennis also considered ring debarkers. A Boise Cascade plant across the U.S. boarder was using one. But this debarker, too, had its issues. The U.S. Boise Cascade plant could only run a single log through the debarker at the time, and they had to singulate the logs using a step feeder ahead of the ring debarker. This required a lot of space for the setup (the company was trying to open up space), and it would severely bottleneck the system at the Ontario plant. While running a single log through the debarker at a time may work for sawmills debarking 60’ softwoods, it’s too slow when running short wood lengths.
To keep up with their production needs in Ontario, they would have to install four ring debarkers. That would lead to another drawback for these machines. Because these debarkers each required an operator, the company would have to add manpower.
Going with Rotary Debarkers
After considering these options, Dennis then saw an advertisement for a rotary debarker. It caught his attention. In February of 1994, he arranged for trial of the debarker in Northern Alberta. It was the middle of winter, and the machine was debarking frozen logs. As soon as he saw it running, he was sold.
He wouldn’t have to singulate the wood—roller debarkers are mass-feed systems. He could easily adjust it (unlike drum debarkers). And he could easily discharge the logs over a gate.
He contacted the debarker’s manufacturer, and the company designed a machine with 36” rotors—big enough to meet the production demands at Boise Cascade. Dennis and this team bought three, 50’ identical machines. They were able to put them in one building, feed them off of one conveyor system with a plow, and discharge them to a chain conveyor.
They installed the debarkers in 1996. The debarkers were the first installation at a paper/pulp mill in North America.
After installing the machines, word spread, and companies stopped by the Boise Cascade plant on a regular basis to view the machines. Dennis soon became an expert on them and eventually moved onto a sales position with a manufacturer that produced its version of these debarkers.
Why Roller Debarkers Work
Roller debarkers work in cold climates because, unlike drum debarkers, they debark through mechanical means. While drum debarkers rely on friction to debark the wood, roller debarkers cut the bark with abraders, and these cuts work with the friction caused as the logs tumble against each other to peel them.
Roller debarkers are excellent machines for debarking virtually any wood. They handle frozen wood, softwood, and hardwoods. They even handle species with stringy bark.
Biomass Engineering & Equipment offers roller debarkers for the global market. Built to your specifications, our roller debarkers are the right debarkers for high-volume pulpwood processing.
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