Application of permanent magnet motors to solving a paper mill production problem

ABB's commitment to the customer and groundbreaking technology helped a paper mill overcome a serious challenge to improve its processes.

Michael Kozlowski, Pulp and Paper Consulting Engineer with ABB Process Automation, presented a case study at Automation & Power World in Houston about a paper mill company that solved a production problem using ABB’s permanent magnet motors. Mike has  22 Years Drives and Power System Experience, and is a Senior Principal Engineer for the Paper and Forest Products Industry.

The issue

The paper company had a number of problems:

• An obsolete DC Drive System
• DC motors had worn/threaded commutators- prevalent on the wet end of the machine
• High number of gearbox failures, especially in the wet end of the paper machine

The challenge

The customer had his management’s directive to speed up and slow down the machine to produce different grades of paper. Some questions needed to be answered through ABB’s consultative approach:

• What are the limitations of his existing drive system?
• How much horsepower would he need?

The process

The ABB account manager set up a meeting to discuss needs with mill management. The mill confirmed they wanted the capability of running slower with higher basis weight linerboard and to run lighter paper grades at higher machine speeds, and they also wanted to know the budgetary cost.

As is customary at ABB, the customer’s needs drove the system solution. They needed extremely high reliability and the lowest energy cost. ABB Process Automation performed a survey of the machine to produce a set of preliminary findings in a report, which including analyses for theoretical vs actual calculations, to verify ABB was on the right path to understanding the drive system power requirements in all of the customer’s production cases – from a motor and drives system perspective.

The solution

ABB recommended the following solution:

• An ACS800 AC Drive system
• Direct drives with permanent magnet motors, which produce extremely high torque without the need of a gearbox

The reason for this recommendation is straightforward: typical Induction motor rotors rely on a short circuit of rotor bars (and slip) to produce torque. In direct drive motors, permanent magnets are inserted in the rotor to produce torque.  The result is a wider product speed range, very high torque at low speeds, more power dense while completely eliminating gearbox failures.

Summary

ABB supported this end user by providing a completely different and innovative way to look at modernizing their drive system. ABB also provided a path and solution that would allow the customer to meet all process criteria for modernizing their machine from a drives, motors and control perspective.

Click here for more information on direct drive solutions for the pulp and paper industry.