Sheet break reduction initiative yields quantifiable production improvements
By Pulp & Paper Canada
Like many mills in the industry, Abitibi-Consolidated's Fort Frances mill suffered deteriorating production from one of its paper machines. PM7 is a 210-inch, 1920-vintage, Valmet Bel-Baie III paper m...
By Pulp & Paper Canada
Like many mills in the industry, Abitibi-Consolidated’s Fort Frances mill suffered deteriorating production from one of its paper machines. PM7 is a 210-inch, 1920-vintage, Valmet Bel-Baie III paper machine, rebuilt in 1984, which makes value-added paper for communication. It was running at an average of 2970 ft/min, suffering an average of 2.3 wet end breaks per day, with an overall equipment efficiency (OEE) of 69.4%. The average downtime for 2004 was 75 min/day.
In spite of the mill’s various improvement initiatives, they could not sustain their performance gains, and the benefits gradually decreased over time.
“Abitibi was looking for a new sustainable method to improve the paper machine production,” said Jorg Ruppenstein, process control engineer at Abitibi. “We were looking for a quantifiable data driven approach. This would enable us to compare our performance before and after the project, so that we could measure a true economic benefit.” Abitibi partnered with Matrikon to perform a joint sheet-break reduction initiative. Abitibi provided all of the necessary plant data and plant operations experience. The core technology for this effort was the Matrikon pre-project / post-project process monitoring software, and the company also provided the tools and expertise to perform the advanced data-mining monthly moving average and analysis.
The project was broken into four distinct phases:
Phase 1: Interview and knowledge discovery
Phase 2: Data collection
Phase 3: Data mining and analysis
Phase 4: Defining improvement projects
The data analysis used eight months of data that was already stored in the mill’s process data historian. This data included information from the paper machine’s automation systems (distributed control systems, quality control system, and programmable logic controllers) drives and other sources. The analysis enabled engineers from both the mill and the supplier to make the following conclusions: The root causes were classified into three major process areas:
* Stock prep and stock proportioning;
* The steam system; and
* The draw system.
A total of the breaks were related to changes in the broke system, while 15% of the breaks were related to dryer section differential pressure variability along with dryer motor current variability. A second sheet break followed the first sheet break within 30 minutes, 15% of the time, and 15% of the breaks were preceded by large changes in draws.
The team identified 50 improvement opportunities. The top five were:
* Changes to the broke addition logic and piping from three parallel streams into a single stream
* Repairs to the dryer controls and instrumentation
* Re-commissioned the white water silo temperature control system
* Mechanical repairs to eliminate debris hung up and release after a break
* A change in the stock proportioning logic so that broke only displaces virgin groundwood and not virgin kraft
Since the goal of the project was to deliver sustainable improvements, the team calculated all measurements over a nine-month period after the project. The results were impressive. The average wet end sheet breaks per day reduced by over 40% (from 2.30 to 1.36 breaks per day). The average production rate increased by 12% (from 303 to 338 tons/day). Average downtime reduced by 37% (from 75 to 47 minutes per day). OEE (overall equipment efficiency) increased by 8.3% (from 69.4% to 77.7%)
“This software helped our Fort Frances paper mill realize over $1 million in savings during the first nine months alone,” said Ruppenstein. “We have a sustainable, quantifiable data driven approach to improve paper machine production. It was truly a team effort.”
Abitibi has future plans to deploy this solution throughout its mills.
Jorg Ruppenstein is a process control engineer at Abitibi-Consolidated Company of Canada, Fort Frances Division, E&I Services.
Abitibi-Consolidated plays a big role in the story behind the headlines at major newspapers around the globe, serving clients in some 70 countries from its 45 operating facilities. It is the single largest newsprint producer in North America and a significant source of supply for the global marketplace, with customers around the world. As the North American leader in newspaper and magazine recycling — and a major one in the U.K. — the company harvests 1.9 million tonnes of fibre each year from the “urban forests”, transforming the material into newly manufactured newsprint that will carry tomorrow’s headlines. The newsprint business employs approximately 4,500 people at its 11 paper mills and extensive network of recycling facilities.
It also ranks first in Canada in terms of total certified woodlands.
The Fort Frances facility has just under 700 employees and, with three machines, produces Very High Bright uncoated groundwood grades, SCA+ and NBSK market pulp. Key paper grades are high quality heatset, supercalendered SCA+ and coldset papers.
Its production capacity is (value-added): 286,000 MT; market NBSK: 87,000 MT for a total of 373,000 MT.