Friday August 22, 2014





Domtar's efficiency advantage

New conveyor-belt system makes mill 16 times more efficient
Keith Anderson

Bill Adams stands beside the new chip conveyor belt system.

The enterprise of Domtar’s Kamloops mill is all about converting wood fibre to paper-grade kraft, a business that’s gained multiple new efficiencies in the course of cutting power consumption.

Taking 18 months from design to construction, and utilizing a $2-million subsidy from B.C. Hydro, the new system has replaced a pneumatic, chip-blower in use since the mill’s opening in 1965 with a mechanical conveyor-belt system.

That may not seem a revolutionary change, but due to the one component, which rolled into operation in November, the mill is 16 times more efficient.

“We’ve looked at it as sort of a transformative project,” said Bill Adams, manager of strategic planning and engineering at the pulp mill. “That’s how B.C. Hydro looks at it as well.”

Concealed from view by cladding, the new belt zigzags over a distance of 500 metres, carrying woodchips from where they’re piled to the top of the digester, 40 metres above the ground. A variable frequency driver assures that the system delivers chips only as fast as the cooker needs them.

Adams gave The Daily News a tour of the system on Wednesday, pointing out its various advantages.

While a pneumatic system is cheaper to build, the belt system saves 7.9 gigawatt hours of electricity per year. That’s roughly the equivalent of the power used by between 700 and 900 homes and represents a savings to Domtar of $350,000 a year. Electrical savings accrue from the use of two 75-horsepower motors instead of the old 1,500-horsepower one.

Yet the power bill is but one part of the equation, Adams explained.

“I would say the greatest benefit of the project is that it actually saves fibre. We’ll get a higher yield.”

This is because the new system has a built-in efficiency — carrying the chips instead of moving them with air pressure.

“When you blow chips 1,500 feet, you actually break them up a bit, especially mountain pine beetle chips, which are drier. The chips are always breaking and it’s lost yield that doesn’t get transformed into fibre.”

They can produce the same output using fewer tonnes of chips. The belt system now saves more than $1 million annually on chip costs through improved digester yield. It also cuts annual maintenance costs by $126,000, since the old system needed regular replacements of worn piping and blower rebuilding.

Those sorts of savings can buy considerable competitive advantage in a global marketplace.

As well, with the chips processed at a higher state of quality, there may be improvements gained in the final product.

“We’re sampling chips every couple of days and so far it indicates we’ve achieved the benefits we were looking for.”

About 40 additional workers were employed at peak construction of the conveyor belt under the guidance of project manager Dennis Casol.

Domtar didn’t release the value of its investment in the new system, citing competitive concerns, but the conveyor is part of investments in energy efficiency and environmental upgrades worth $120 million since 2011.

“This is really a 20-year investment for us. It’s really well designed.”


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