New scanning sensors, soft sensors, open-ended multivariable control, and the first steps to integration with web inspection are expanding the definition of quality control.
It’s been almost 50 years since the first computer-based paper machine quality control systems hit the market. Over the intervening years, a lot has happened to advance the scope and effectiveness of the measurement and control capabilities.
In this exclusive interview, Valmet’s Jari Almi, director of quality management systems, and Seyhan Nuyan, director of pulp and paper applications, discuss new developments and the direction of the technology and applications. Valmet has recently introduced a new QCS that incorporates pre-machine furnish measurements as well as scanned dry sheet measurements and associated multivariable control, stretching the boundaries of measurement and control systems.
Paper360°: What were the reasons for the introduction of a new QCS at this time?
Nuyan: When it comes to quality management, our approach has been to expand the scope of automation. We’re moving from standalone and individual control loops that manage only one papermaking problem to developing new technology and managing the key quality variables in a multivariable setting from furnish to end use properties and, finally, profitability of the enterprise. Our new QCS is another step in this strategy. The QCS market is essentially a replacement market, so our solutions need to offer more than just solving obsolescence at a competitive cost. Also, by recognizing the fact that initial investment of a QCS replacement is a fraction of the total cost of ownership, the new offering was targeted to minimize even further the cost of ownership after the initial capital investment. This has helped us to reach a record in competitive replacements.
Almi: Our product development was started in 2012 to aim for a product portfolio launch in 2015. Our goals included new spearheads specifically for tissue, board, pulp, and special paper grades. Luckily, it was a perfect time, considering the automation group acquisition by Valmet in 2015. That meant renewal and customer focus under the same umbrella.
Valmet promotes this system as an application-specific solution rather than a generic product. Please explain.
Nuyan: An application-specific approach is not new for Valmet and is, in my opinion, a must-win strategy in this business. As the needs for tissue, paper, board, and pulp are specific to each application—from furnish to specific end properties—our offering must be structured similarly. That is our differentiation. Using this strategy, we also now have application-specific solutions for converters—such as systems for corrugators, extruders, and self-adhesive laminate machines—and for other adjacent industries.
Some of the unique portfolio of solutions in the tissue segment, for example, include non-nuclear weight and moisture measurement in one sensor, tissue color measurement, softness measurement, both laboratory and online measurement of fibrillation, and prediction of strength properties. Tissue making is an optimization between softness and tensile strength. Imagine the power that multivariable control of these new softness and strength measurements could impart to the tissue producer!
Almi: Our board machine control concept has a new tool to measure and control fiber surface orientation and printability prediction through the IQ Surface sensor. This is also a unique addition to all printing and writing grades. Additionally, in combination with fiber furnish measurements in our Valmet Pulp Analyzer (MAP), the QCS controls can now be enhanced with a new sheet strength prediction capability. This soft sensor concept is a first for a QCS.
Entering the paper and board converting segment with the Valmet IQ quality control solutions is one of Valmet’s growth initiatives. Previously, we supplied a moisturizer system to an SAICA corrugated converting plant in Spain. A repeat order from SAICA for a plant in France and another in Spain is proof that we are on the right track for delivering quality control solutions for the converting industry. By precisely controlling moisture in the corrugators, SAICA’s plants will be able to reduce corrugated board warping and consequently reduce waste and improve productivity in their converting processes.
The tissue softness measurement sounds intriguing. How is tactile feel simulated? What are the proposed ways to manage it?
Nuyan: This is indeed quite intriguing. The tactile feel correlates quite well to a filtered image of the tissue surface topography. It has been obvious to machine operators that the sensor output was predicting when they should change yankee blades to achieve the required softness quality with longer blade run times, hence saving money. Before long, we will start seeing optimization applications between softness and strength properties or possibly between other properties such as tensile energy absorption (TEA), elastic modulus, or roughness.
Many factors impact softness, including furnish selection, coating chemicals, creping, layering, moisture uniformity, and pressing. With the addition of the softness measurement, we have more eyes on the process to help manage it, which is happening now in manual mode. Our understanding of the softness mechanism will increase quickly now that it can be measured online with immediate feedback.
What other scanning measurements are being introduced?
Nuyan: We have introduced a very versatile, single-sided moisture measurement that can be used in multiple fixed-point positions from the press to the reel, or on either a full scanner or a single-sided scanner. Another unique attribute of this sensor is the ability to measure from distances up to 50 cm. This moisture measurement on the new single-sided scanner also offers a good solution for converting and corrugated boxboard applications. For converting there is now also a new silicon measurement, which can be used to minimize the cost of silicon.
Almi: We have introduced a fiber orientation control concept with surface orientation and total orientation measurements. There are separate measurements for surface fiber orientation of coated board to prevent diagonal curl, and total orientation measurement for lighter weight grades.
For pulp dryers, we have a new microwave measurement that measures fiber weight and moisture simultaneously. The value is a lower investment cost and lower life cycle cost since there is no radiation measurement related to maintenance costs.
Compare the system’s multi-variable controls to traditional feedforward/feedback controls. How does this change the way paper machines could be controlled now and in the future?
Nuyan: Multi-variable controls are more flexible than traditional controls. More controlled, manipulated, or disturbance variables can be incorporated into a single controller. Valmet service personnel can add new process areas at a mill site without the need for reconfiguration and system generation.
Another important aspect of the new IQ Optimizer is the incorporation of a proper database so that grade management and reporting functions can be done easily. Management information applications and online and offline analysis tools (like machine monitoring and spectral analysis) can use the database.
Almi: Our new IQ Optimizer is more open in the configuration point of view. This provides an opportunity to connect all wet end analyzers and consistency measurements into MD control to improve overall process stability.
For the first time a QCS and a web inspection and break analysis system are being proposed as a related solution. What is the degree of commonality or integration?
Nuyan: This is still in its infancy, with just a few limited applications coming now into the same family. In one of the integrated applications, customers can view the defects seen by a web inspection system on the same map where the QCS profiles can be displayed. Operators can visualize relationships between QCS measurements (for example, web moisture) and defects, and possibly find correlations. Information from both systems can be combined into custom-designed reports according to the need.
Is the new technology in this current system compatible with previous Metso and Valmet QCSs?
Almi: It is fully compatible with previous generation systems back to 1995. We also promise forward compatibility to future systems. One of the biggest decisions in 2012 was to define our policy to not cut compatibility with previous-generation systems. We could have made far bigger innovations in the new system by cutting the compatibility. Instead, we want to continue offering improvements to existing customers. It’s like putting a new, more powerful engine in an old car for better performance. With Valmet IQ, we can offer even a 1995 system the latest measurements and controls.
In recent years, total cost of ownership or lifecycle cost has become an influence on purchasing decisions. How does this new system address those costs?
Nuyan: The system’s modularity and new design features allow for easy expansion. Upgrades are now easier to make, require less rework, and are hence less expensive. Also, there is increased capability for machine diagnostics and variability analysis tools to visualize and warn of developing problems.
Almi: Full backward compatibility provides the latest features for our installed base, thereby improving paper quality, providing fiber and energy savings, and other benefits that you cannot reach with traditional upgrades of an obsolete system.
Where do you see QCS technology and applications heading in the next five to 10 years and what will be the impact on papermaking?
Nuyan: The transformation from being simply a measurement and control system to becoming an “operator’s friend” will continue with a focus on controls and applications that help the operators at many different levels. The enabling factors in this transformation are new measurements that are fast enough for machine and process troubleshooting, MD/CD decoupling capability, growth in multivariable controls for MD and CD, and sophisticated analysis techniques. Holistic strategies will be implemented as a result. This includes the ability to incorporate the important properties of the specific grade and the strategic targets of the enterprise to make decisions on how the process should be run—for instance, which control knobs should be used and where they should be set; or what actions are taken when the system issues warnings, makes recommendations, and schedules downtime. At the end of the day, the system is able to contribute to the profit picture.
While there will still be hardware sensors, increasingly the use of soft sensors will enter the control domain. The concept from “pulp properties to paper properties” will continue to be developed to the level that upstream actions can be taken with the new control techniques. Fiber characterization and soft sensing will help us control paper properties that we cannot today.
Almi: The development of grade-specific solutions will continue, but maybe the biggest leap will be to introduce more advanced quality controls for papermaking. In recent years there have been a lot of new measurements introduced and, along with increased computing power, there should be a way to better use all this information to control the machine effectively.
Big data techniques will unleash a number of new applications to make a QCS truly an operators’ companion. The industrial Internet, remote connectivity, and mobile devices will be used in this context. New service concepts will be developed based on the new technologies.
Mark Williamson is a journalist engineer based in Ontario, Canada. Contact him at [email protected].
Valmet’s new system takes the first steps toward integrating QCS and web inspection.
The Valmet IQ has new scanning sensors for tissue softness, fiber orientation, surface printing quality, and more.