Are you spending too much on fiber? Do you need to improve fiber yield in your operation?
BTG’s expert, holistic approach, TTC – Total Tissue Capability, can help you measure and control your process and save you hundreds of thousands on fiber.
For years, fiber yield optimization in tissue was not taken seriously. However, in the past couple of years, given the rapid price increase of fiber and the desire to become more environmentally conscious, there has been a resurgence to improve fiber yield in tissue. And seeing that fiber represents about 45% of the total cost to produce a ton of tissue, good consistency measurement and control can save the tissue maker a lot of money.
An important tool is routine consistency checks to verify consistency transmitter calibration as units can otherwise rapidly become a source of significant error, resulting in poor fiber blending and/or layering and cost overruns. For example, on a typical premium tissue machine with a layered headbox, a change in control accuracy of as little as 0.1% can increase a mill’s fiber cost by $100,000 - $150,000 per year.
A quick cost analysis highlights the downgrade of a premium tissue product because of poor fiber blending, along with the subsequent impact on its handfeel softness target.
This is a typical virgin fiber tissue mill producing 67,000 tons/year of premium- and value- brand tissue products. We assume premium tissue has a MSP (Manufacturer’s Selling Price) of €3,700/ton and value tissue of €2,400/ton.
If just 1% of the annual production had to be downgraded for low softness, the mill would lose €870,000/yr in profit. Figure 2 illustrates the typical difference in manufacturer’s (MSP) and retail (RSP) selling price for three different product segments.
On many premium tissue machines, scanners to monitor and control basis weight and other process parameters are often not used because of the large amount of dust. However, without a scanner, controlling to a basis weight target with minimal variation becomes much more dependent upon the accuracy of the consistency transmitter.
Poor consistency control often results in tissue makers needing to run at a higher basis weight target to ensure they meet the final sheet properties when producing the sheet at the low end of the target range. By reducing the variability, there is an opportunity to lower the basis weight target. The graphic below illustrates the benefit of accurate consistency control.
For our tissue mill example listed above, improved consistency control allows the mill to reduce the basis weight target from 18 to 17.9 gsm. This 0.1gsm reduction in basis weight (or 0.55% fiber savings) will save the mill 372 tons of fiber (fiber €600/ton) or €220,000.