A new tissue category, NTT, gives bulk approaching TAD at costs near DCT.
Perini Journal
Metso is introducing a new concept in tissue making to produce what it calls ‘textured tissue’ that offers high bulk and softness properties at the same time as it gives big energy savings compared to conventional or structured tissue grades. The high-bulk sheet can also mean significant fiber savings as well, the company says.
The key benefits of the new sheet, and the patented Advantage NTT™ process behind it, include the ability to make textured tissue with high bulk and excellent softness and handfeel. Additionally, the new configuration allows high post-press dryness in the range of 44-47% solids, which translates into considerable thermal drying energy savings. Energy input per roll, depending on the product made, can be decreased by up to 20%, says Metso, saving money and also reducing the carbon footprint of NTT tissue products.
“Textured tissue is an entirely new product category, made with our NTT concept,” explains Jan Erikson, Vice President of Sales at Metso Tissue. “This development is a result of carefully listening and responding to the market needs, as our customers are always asking us for a way to make excellent product quality at low operating costs. NTT is it. And textured tissue is a new category in the classification of tissue qualities, which are traditionally categorized as either conventional or structured. NTT is better as it gives unique sheet characteristics and savings of both energy and fiber.”
Other benefits include extreme flexibility of the process to allow various degrees of NTT texture, as well as quick changeover to production of DCT if needed. Increased productivity thanks to high machine speeds, approaching 1,600 or even 1,800 mpm for NTT, is also possible. The process is also flexible as far as grade, making bath tissue, facial tissue, handkerchiefs and kitchen towels.
ENERGY SAVINGS VERY TIMELY. Erikson explains a bit of the background on the NTT concept program, which began around early 2006. “We decided very clearly to start from the viewpoint of the tissue maker, as opposed to starting from the technology. Thus the focus was on product quality and the cost to make that quality, with the target to make high quality and high bulk, at costs close to DCT. We initially considered 8 or 10 possible concepts and were quickly able to pinpoint the NTT configuration as the one that offered the most promise for quality and cost.”
Energy costs were important, but not the main aim from the start. As energy prices have skyrocketed over the past two years, and the NTT configuration has proven to be very energy efficient, the timing could not have been better. Metso says it was somewhat surprised that the NTT concept was so efficient at water removal but the ability to deliver very high post press dryness and the corresponding reduced drying energy was incredibly timely.
TECHNICAL DETAILS QUIET FOR NOW. The concept is at this point still in the pilot plant stage and Metso is not publicly releasing much in the way of technical details. NTT project manager Ola Thomasson, however, says that the configuration “is entirely based on the latest, state-of-the-art machine technology that has been proven in the field and now reconfigured and literally turned on its head to come up with these exciting qualities and process advantages.”
Furthermore, he says, this technology leap is the result of recent advances that have been made in various components. “This is based on proven machine technology that we have smartly put together in a patented configuration.” The NTT technology was officially launched at Metso’s Tissue Making Conference in Karlstad, Sweden in mid September.
IMPRESSIVE SOFTNESS AND FIBER SAVINGS. Ingvar Klerelid, Metso Tissue’s VP of Technology, is clearly impressed with the combination of energy savings, fiber savings and product quality. “NTT has excellent softness and bulk. The bulk is 50-80% higher than what is achieved on a conventional DCT machine and is close to TAD products. The NTT process is easy to run at high speed, which makes it ideal for production of high quality bath, facial and napkins. Towel products can also be made and this is better than dry crepe though we don’t claim to reach the level of TAD products.”
“The increased bulk of 50-80% can be used in different ways,” continues Klerelid. “The most obvious way is to reduce the basis weight, with a 10% reduction easily achieved.”
“An alternative is to reduce the weight of the finished roll. The high bulk makes it possible to maintain the roll diameter and roll firmness, but have lower sheet count in the roll. The roll weight can thus be reduced by 20-25%. Furthermore, the high bulk can also be used to improve surface softness by calendering. This can be very interesting for facial tissue.”
RESPONSIBILITY TO DEVELOP NEW PRODUCTS. “We see it as our responsibility as the market leader in tissue technology,” concludes Jan Erikson, “to use our resources to bring new products to the tissue market. NTT fits very well into our current product portfolio as a new category. We feel NTT allows companies that are considering making tissue that has better product characteristics than DCT to take an important step up in quality with very little risk.”