To keep up with the demands on press felts and increase their lifecycle, it’s important to obtain complete data on felt moisture and permeability content.
Feature article
1970-01-01
THE IMPORTANCE OF MAXIMIZING WATER REMOVAL IN THE PRESS SECTION
After the forming section, water is removed from the web by compressing it against a press fabric to force water out; the solids (fiber and fillers) remain, becoming increasingly denser and more interconnected. The rate of water removal can be enhanced with other elements, such as vacuums and steam boxes. The aim of course is to remove as much water as possible during this mechanical/hydraulic stage as it is more energy efficient than the thermal phase that follows.
Press felts are responsible for efficient water removal within the press section. This happens when the sheet and felt(s) pass between two rolls that are pressed together, also known as press nips, which squeeze out the water from the web.
This part of the process not only increases the strength and compactness of the sheet, but it will help increase its dryness ahead of the sheet entering the dryer section. This is important to a papermaker's profitability as increasing the dry content in the press section by even just 1% can lead to a 4% reduction in energy use in the dryer section.
That's why its paramount to ensure optimal and uniform dewatering by the felts throughout their entire lifetime. However, to create the appropriate and mill-specific felt conditioning program, papermakers as well as chemical and felt suppliers need accurate, reliable felt moisture and permeability measurements.
Operating the press section is the most economic way of achieving the highest dryness and optimum smoothness before going into the dry section.
HOW ABB CAN HELP
Proper cleaning, conditioning and lubricating enables the press felt to take water and be dewatered uniformly, ensuring max dry content and runnability. And accurate, regular felt data is the first step to an effective felt conditioning program. ABB's L&W Felt Moisture and Permeability Meters provide absolute results that are the industry standard for felt moisture and permeability measurement.
DUAL PURPOSE EXPANDS FELT MEASUREMENT USE FOR MILLS AND SUPPLIERS
Having helped identify the effectiveness of felt conditioning for decades, these instruments provide the data—and updated functionality—necessary to optimize the press section. That’s why ABB’s newest felt instruments can be used in multiple modes of operation (as a handheld device or inside an online scanner) to maximize your investment.
ABB's instruments can be used in traditional handheld operation.
Using ABB's felt instruments in online scanners enables more frequent measurement and optimized conditioning
Traditionally, felt measurement was done by handheld operation but in modern papermaking, more and more mills are adding scanners. These online scanners help meet stringent safety requirements that remove the need for operators to enter the machine. They also provide the opportunity for more frequent measurement, leading to big cost savings opportunities.
Benefits:
- Understanding when machine is running well facilitates easier troubleshooting
- Improved conditioning extends felt lifecycle
- Better performing felts improve runnability
- All of which reduces costs in energy, maintenance, and cleaning chemicals
Weekly permeability measurements
Daily permeability measurements
When raising measurement frequency, you can also follow up on temporary changes in for example, chemical batch cleaning, press nip pressure, vacuum level, water heating etc. You get more granularity and clarity in the data, as the above example illustrates.
Regular, daily measurement provides a reference point in time, helping to detect machine disturbances and downtime due to web breaks. It also makes it easier to determine when to clean the felt and to see the effect of the cleaning—saving mills money.
ABB MAKES INCREASE IN DATA EASIER
Not only do our enhanced felt instruments enable papermakers and suppliers to complete more moisture and permeability measurements, but the included PressView3D software will make the felt data increase easy to analyze. Available on a a PC with built-in 3D data mapping, HD data storage, and the ability to save only the data the matters, users benefit from additional analysis without extra work.
