After debarking, removed bark that contains few useful fibers is typically used to provide fuel to make the steam used in the pulp mill itself. In order for this bark to be fuel efficient, it needs to be as dry as possible. That’s where the use of on-line, near infrared (NIR) moisture meters comes in. They instantaneously and continuously measure moisture content to help ensure efficient fuel usage.
However, it isn’t just the dry bark portion of the pulp making industry that requires careful monitoring and adjusting of moisture content. Market pulp is made specifically to ship to other locations where it is then converted to paper. Normally, it must be delivered in bales of about 10% moisture content. This moisture level must be monitored by the OMNIR on-line near infrared moisture sensor in order to minimize the fiber to fiber bonding to make it easier to disperse the pulp in water for later processing. Other types of pulp are dried to 5-6% and supplied in rolls. Again, on line moisture measurement is essential.
In order to achieve the right moisture percentage, it’s critical to measure at various points throughout the process. For example, some types of pulp start out at 50% moisture content and are flash dried to meet the specific standards via hot air treatment in a vertical silo. At this point in the process, there is the risk of incineration if the pulp is too dry before it enters the hot air silo.
All finished papers made from pulp have a moisture percentage that varies from about 2% to 12% depending on ambient conditions. The type of pulp, method of refining, and the chemicals used in its manufacture also affect the moisture content. Regardless of the steps utilized, it’s imperative that paper fall within this range. Anything outside of this range and every single physical property is open to negative impact.
By implementing accurate and efficient moisture level monitoring throughout the process with an intelligent system that works together to optimize your process, you can ensure the best possible outcome for all the necessary properties such as: opacity, permeability, porosity, roughness, compression strength, stiffness, tear resistance, breaking strength, smoothness, electrical resistance, and many other properties.
Gravimetrical calibration of typical on line moisture scanners in large paper mills is a time-consuming process and not accomplished nearly as often as is needed to ensure consistent quality. That’s why we’ve created our on-line meters to provide instantaneous, non contact, non destructive moisture results in real time on either end of the paper machine. This model is useful in all stages of the paper manufacturing process including checking the pulp sheets before the pulp mill, incoming pulp sheets before processing, and paper products received and converted at the converting plant. Near Infrared (NIR) is also well suited for measuring water-based coating and coat weight thickness. This allows papermakers utmost confidence toward achieving tighter cross direction and machine direction moisture control assuring faster startups and grade changes, all while assuring increased productivity, product quality, and substantial energy savings.
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