Technological Audit unlocks nice surprises

Inland Empire operates a single-machine mill, with a capacity of around 175,000 tpa of mainly standard and improved/hi-brite newsprint. They use both virgin and recycled fiber, but had for some time been suffering with inconsistent quality from their thermo-mechanical pulp (TMP) line. As Production Manager, Donnie Ely, points out, “Some days the quality was good, some days it was bad, and we didn’t know why.” Tanner Gerety, Pulp Mill Supervisor, agrees: “We’d been trying everything and asking a lot of different people, but something wasn’t adding up. So we decided to call ANDRITZ.”

CHANGE IS CONSTANT

Inland Empire’s TMP plant was almost completely rebuilt by a competitor firm in 2009. However, by the time they called ANDRITZ, the refiner line was no longer optimized for the (soft) wood raw materials that the mill was using. It had also originally been set up differently than is necessary for the mill’s paper products today, resulting in variable refining efficiency and energy consumption. In effect, the TMP line would not actually have been able to achieve the mill’s quality targets, as it was being operated.

ANDRITZ responded by sending Christoph Ernet, Director of Process Technology for HC-Refining, to Spokane in 2022, with the aim of helping to set up the refiner operation and improve fiber quality. Once there, he carried out a Technological Audit, one of three options available in an ANDRITZ Process Performance Study (the two other options are a Mechanical Audit and an Automation Audit).

The Technological Audit assessed the TMP line step by step, taking samples of the pulp at different stages. The main focus was on the high-consistency (HC) refiner, which was also suffering from large motor load fluctuations, varying by 100% from minimum to maximum.  

NEW THINKING

The audit recommended several process changes, and this is where the nice surprises began for Inland Empire. Tanner Gerety explains, “Christoph had a completely different way of thinking about how to operate refiners. We had been taught to operate the plant in a certain way, but Christoph said we would get better pulp strength if we did the exact opposite of what we had been taught!”

And it worked. “The results were very positive,” says Donnie Ely.

While Christoph Ernet was at the mill, the ANDRITZ/Inland Empire collaboration fine-tuned both HC-Refiner stages, and the proposed changes were then tested, to reveal which machinery settings correlated with which pulp quality results. The whole process lasted a week. Christoph Ernet also gave tips on which areas to focus on, when running the plant in the future (chip washing, valve maintenance, screening and reject treatment, to name just a few). Tanner Gerety observes: “Having an expert in the field, 1-on-1, was the biggest learning experience. I’m now so much more confident talking to my operators.”

“HUGE INCREASE IN FIBER LENGTH”

Since the audit, the mill has had a lot more homogenous and better pulp quality. Tanner Gerety continues: “Operation of the TMP refiners has gone well. Using what we gathered from our trials with ANDRITZ, we have been able to run the refiners [as Christoph recommended] and have better fiber strength. One of the biggest changes was a huge increase in fiber length and an overall decrease in shives and fines.” He also reports higher tear strength, a 40% rise in tensile energy absorption (TEA) on the paper machine and a 20% increase in pulp freeness targets. “A lot of it is about keeping the refiner producing at a consistent rate. There was a lot of speeding up and slowing down before, but when you’re operating consistently, you can fine tune it. That’s one of the biggest influences on pulp quality.”

Donnie Ely also points out, “Now that our pulp quality is good, it has allowed us to focus on other things. We’ve lowered our chemical costs. And the better pulp strength has reduced the number of paper sheet breaks by half, so we’re now running the paper machine more reliably.”

A WORLD OF EXPERIENCE

Because ANDRITZ has knowhow from a wide range of pulp and paper mills around the world, an audit from ANDRITZ is a little like having access to many of the world’s best practices for every piece of equipment in your mill. Christoph Ernet says: “All mills work differently, but we can analyse all plants and explain all of their advantages and disadvantages.” In this particular case, “We dealt with Inland Empire’s exact specific questions and showed them how it could work”.

This was already the seventh project at Inland Empire, since the company’s relationship with ANDRITZ began in 2018. According to Mark Lacasse, Product Manager, ANDRITZ, the cooperation on this particular project with Inland Empire was exemplary: “It was outstanding, actually! They were open for trials in the TMP plant and followed every proposed step very carefully. With support like this from the mill, it helps us to optimize a plant and get better performance out of it.”

Tanner Gerety says: “I just wish we had done it four years earlier!”, while Donnie Ely adds, “We’re glad we did it, absolutely. When we have issues, ANDRITZ’s is always there to help out. Even Inland Empire’s President, Kevin Rasler, approves - as Donnie Ely explains, “He’s very pleased, because the results are visible throughout the organisation.” 

That’s the kind of return on investment we like.