A Break From Breaks

Kadant Dryer Management System (DMS) for SBS Producer Saves Time & Assures Quality

"SBS (solid bleached sulfate) board producers are in a business where every minute counts. Fifteen minutes a day gained in quality output can equal over $1,000,000 per year!" says Jim Maggard, system development manager at Kadant Johnson.

"An ideal way to give operators the freedom to use their time more efficiently is our DMS® (Dryer Management System) control system, positively impacting sheet quality, and getting production up and running quickly after less frequent breaks."

At one leading SBS mill, operators faced threading problems on a chronic basis. With the DMS system, there's an automatic threading set point, so that "too wet or too dry" is no longer a concern. In the past, there was always lost production due to off-spec moisture following breaks. The DMS system allows for focus on getting the machine up and running.

Motive steam can be saved during lower speed operation, provided the right changes are made. When the machine is dryer limited for a significant percentage of production due to supply header pressure issues, motive steam can boost drying.

Goals prior to the DMS system optimization

For the DMS system to be most effective, better instrumentation was needed, such as flow meters, and other ways to observe machine performance and energy usage.

Continues Maggard, "The production team needed to effectively monitor and track differential pressures to calculated set points. Without an accurate means to determine condensate load, there was no easy way to know what differential load was best for us on a grade-by-grade basis. Differential pressure variation caused reliability problems, as well as wasting steam. Often, steam went to a condenser, and then back to the powerhouse; not drying paper."

One of the most impactful changes was phase one of the project where pressure transmitters were put on each steam section. This move alone allowed operators to more clearly see each section of drying more clearly. The pressure transmitters were installed on the steam side and on the condensate side—all aimed at controlling steam pressure and differential pressure.

Kadant Johnson's Dave Vijh, senior process and control engineer, did the programming, linking to the DCS network. This included operator training. "We helped operators see for themselves how to optimize."

Vijh points out, "This board mill team's ability to minimize time and waste associated with breaks is the heart of their success. They also make grade changes more efficiently, opening the door for considerable energy savings. In addition, time saved every day equals more quality output, allowing operators to do troubleshooting and preventive maintenance."

Continues Maggard, "It's only normal from operator to operator to see variability. The DMS helps them find their groove for all grades at the maximum output. They know where the bottlenecks are grade-by-grade, and now can aggressively pursue overcoming them."

Concludes Vijh, "The true beauty of the DMS system is freedom for the backtender. Now, backtenders can manage a break and speed up the thread-up time with intelligent software."

Source: Kadant

 
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