Process control pioneers pass torch as new era begins in industry

Pulp & Paper, Jun 1994 by Fadum, Ole

IT'S THE PASSING OF AN ERA FOR PROCESS CONTROL. Three of the pioneers who changed the way that paper machine quality parameters are measured and controlled have recently turned over the daily operation of their companies to others. They are David Bossen at Measurex, David Nelson at AccuRay (ABB), and Alois Kohl at Lippke (Honeywell).

Together, they and their companies have helped the paper industry meet the increasing quality demands of their customers--the printers and converters. These pioneers helped the industry save millions of dollars by increasing fiber yield while educing energy and chemical costs, and by gaining incremental production from existing machines. Last month I had the privilege of speaking with each of them, getting their thoughts on the progress of process control, the direction it is heading, and how papermakers can get the most from it.

DAVID BOSSEN, MEASUREX

Dave Bossen is the most successful measurement and control entrepreneur in the pulp and paper industry. Bossen started Measurex in 1969. By 1993, he had built it to a company with revenues of $254 million and 2,250 employees in 30 countries. He recently became chairman and chief executive officer, handing the day-to-day operations to John Gingerich, who is now chief operating officer and president.

His vision from the beginning was to secure outstanding economic results for his customers so they could afford to pay a price that would enable Measurex to have outstanding economic results for both its employees and shareholders. In addition, he wanted to provide an opportunity for personal growth for the employees so that as the company grew, they would grow. Bossen also wanted Measurex to be an enjoyable place to work.

P&P: What do you consider your most important contributions to be?

BOSSEN: We changed the way the sensor and computer business was done in the pulp and paper industry. We were the first company to provide turn-key, prepackaged systems consisting of digital sensors, digital controls, and operator video displays located on the mill floor.

Because most mills could not support these systems and get a 99% uptime or better, we provided the required onsite services. These service people are often referred to as baby-sitters. I prefer the fireman analogy, where our service people at the mill site can respond immediately to systems problems. Anything less would be too expensive due to the large expense of paper machine downtime. You can't be down while you wait for an expert to arrive. Like a good fireman, the onsite people reduce the need for emergency actions by doing good preventive work.

However, today's service people are more and more like value-added consultants. Instead of reacting to problems, they are proactively working to improve the process as a partner with our customers.

Between 1963 and 1968 only about 70 computer systems were installed. Of these, 50 were IBM 1800s and 20 were based on the GE 4020. If our growth was to be dependent on our customers hiring their own programmers and combining the computer with existing analog gauges, we would be nowhere, as some of the systems at that time took two to three years to implement. I therefore decided to provide the systems on a turnkey and prepackaged basis to the users.

The use of the mini-computer was also part of our business plan, as was digital instead of analog control. We initially used the Hewlett Packard 2116B mini-computer, and this had almost the same power as the much larger IBM 1800. We did all of our control in main memory instead of relying on disks to greatly improve reliability and availability.

Erik Dahlin, whom I consider one of the greatest and most productive control experts, designed our control strategies. Dahlin insisted on keeping it simple so that our people in the field could do the tuning. He used a simple lambda-tuned controller and developed a control strategy that decoupled basis weight and moisture. We quickly went from there to headbox control and coordinated machine controls. The computer also supported the video displays that replaced the older X-Y recorders. The video displays could easily display both machine direction and profile data.

P&P: Measure has made a name for itself regarding sensors.

BOSSEN: We were the first company to develop accurate and reliable digital sensors and the associated digital control strategies. We started with basis weight and IR (infrared)-based moisture. Today, we have some 13 different sensors that can be mounted on the scanning frames. The sensors do not have to be physically lined up, as we make our compensation using software. Our objective--long term--is to put the test lab out of business and get all the measurements online in real time to the papermakers so that they can do something about it. The lab will not totally go out of business, as we need it to calibrate and verify the online sensors. Today we have sensors for basis weight, moisture, caliper, opacity, color, ash, IR coat weight, strength, smoothness, gloss, formation, and extensional stiffness.