Valmet IQDryness checks former dewatering
Valmet, Finland, has extended its quality control systems expertise to the paper-and boardmachine forming section with its IQ Dryness measurement (IQ Dryness). Using microwave technology, IQ Dryness measures the water-layer thickness on the web, which can be used to calculate the web’s dryness. As well as removing most of the water, most paper properties are also developed in the forming section. Valmet says that the inclusion of IQ Dryness in its paper QC family not only opens new possibilities but also helps to close the information gap between the stock-approach system and dry-end quality sensors.
“Perhaps the biggest effect is the better management of dewatering. This has a great influence on the amount of the subsequent drying energy needed with potentially big cost savings in paper production. An increase of just 1% in dryness before the dryer can reduce the amount of energy needed to evaporate the excess water by approximately 4%,” said director Marko Toskala, quality management solutions, Valmet.
Unlike other measurement technologies, IQ Dryness is not sensitive to conductivity which makes it suitable for use with all grades of paper and board. As well as energy savings with vacuum optimization, quicker start-ups, faster grade changes, fewer breaks and improved break recovery are just some of the other benefits that continuous measurement of water removal makes possible.
Optimized dewatering not only improves bonding for multilayer board machines but can also reduce the problems of blow-induced breaks caused by excess moisture in the middle layer entering the drying section. As well, the measurement facilitates on-line fabric condition monitoring and improves troubleshooting of pulsation, vibration and other quality-destroying wet-end problems. The sensor’s small size enables measurement in places previously inaccessible.
IQ Dryness joins the Valmet IQ family of single-point and scanning measurements to provide papermakers with a complete picture of MD and CD moisture from the forming and press sections, through the dryer and size press right up to the reel. Valmet says that together with sophisticated moisture controls and an extensive range of actuators to control moisture levels and profiles, it can close the loop to offer improved efficiency and runnability as well as better paper quality and printing properties.