Lincoln Paper and Tissue LLC.’s announcement that the company would temporarily but indefinitely forgo repairing or replacing a recovery boiler that exploded on Nov. 2, forcing the layoff of 200 workers, didn’t surprise Adriaan Van Heiningen.
A professor of chemical engineering at the University of Maine who specializes in pulp and paper manufacturing processes and biorefinery, Van Heiningen said that new recovery boilers can cost as much as $100 million — a steep investment given the U.S. paper manufacturing industry’s decades-long downturn.
Rebuilding one takes eight or nine months, Van Heiningen said, and can cost $10 million or more, depending on the extent of the damage.
“It is the most expensive piece of equipment in the entire mill. It is a quite complicated device,” Van Heiningen said Friday. “People like to not buy one because it is such a big investment. [Mill co-owner Keith] Van Scotter says the paper market is down and they probably did a calculation that it would not be very profitable to put a hell of a lot of money into rebuilding one.”
Recovery boilers are a key component to papermaking, as they recycle paper manufacturing chemicals cost-effectively and help heat and electrify paper mills.
Explosions such as Lincoln’s used to occur on average once every 30 years in paper mills, but improvements in emergency shutdown procedures have lengthened that timeline, Van Heiningen said.
The United Steelworkers union’s international representative in Maine, Duane Lugdon, recalled that the Georgia-Pacific mill in Old Town experienced a very similar explosion in 1987. A leak from a tube in the economizer section of the Old Town boiler sprayed water onto the boiler’s smelt bed, causing a catastrophic overpressurization and explosion that forced the company to rebuild the boiler, he said.
That job took about eight or nine months, Lugdon said.
Lincoln Paper’s explosion occurred early on Nov. 2, a Saturday morning, with only a skeleton crew at work at the time, Van Scotter said. Lincoln Paper was lucky that the explosion didn’t cause any fatalities, Van Heiningen said.
A recovery boiler explosion at an International Paper mill in Redwood, Miss., in 2008 killed one worker and injured 17 others.
“It is like a hot blade in a kitchen. If it is very hot, and you put a drop of water on it, the water floats on the knife,” Van Heiningen said.
Similarly, the water leaking onto the smelt “forms a thin film,” he said. “It floats almost atop the smelt until something happens: You have a good contact and you have an explosive evaporation. It happens very fast, like combustion taking place.
“It is a bad accident that people die in,” he added, or the explosion pushes the boiler “out of shape, but it is expensive to repair nevertheless.”