STRIKER THE NEW FELT GENERATION: Up to 50% of sheet dryness with traditional presses

At Binet Sul Liri, we consider the felt as one of the most important, or a main vital part of the paper machine. In the past 25 years we constantly worked to improve our felt production quality and considering it as an engineering tool rather than a commodity. If it is valid for the paper and board production, the felt assumes a particular strategic value in the tissue sector.

Sheet Dewatering: Crescent Former Machines

The water removal is essentially generated by the vacuum boxes, suction rolls and traditional or shoe presses but, in all cases, the water has to be carried by the felt and through the felt itself. The paper sheet could reach the press with 12-14% of dryness and generally leave the first nip at 39-41% and 43-44% in case of a second press, actually only on extended nip presses it is possible to overcome these results and obtain up to 48-51% of dryness.
The vacuum generated by one or more suction pumps is considered correct, for high speed machines, when the specific air flow calculated at the suction pump reaches 80 lt/min/cm2 of open area. This value is going to determine the total open area in the vacuum boxes. For suction rolls, a lower specific air flow is generally utilized  (25-30 l/min/cm2) in consideration of the longer dwell time (50-60 ms vs. 1-3 ms of the suction boxes). The vacuum value considered optimal is in the range of 0.3-0.6 bar, beginning from the start-up to the end of the lifetime. The felt’s permeability has to be associated to the paper machine characteristics in order to allow the correct water removal with the different paper grades and machine speed. The typical permeability value for fast machines is about 20 CFM with a start-up conditioning time that can go from a few hours to a couple of days.

Computerized Felt Design

We define the felt design in order to accomplish all the different phases of felt working, like: pick-up, sheet forming and dewatering and mechanical/chemical conditioning. A single tissue felt must have all the features normally distributed on 3 or more felts used for printing or packaging paper grades having much higher speed and much lower weight in grams/m2.
FELT ENGINEERING is also the name of the computerized tool used for designing our felts and for controlling the features of each single layer of both base and batt, and to predict the behaviour of the felt, related to the pressure and vacuum applied during the paper production.

Right from the start, our goal has been to produce the best quality clothing for paper machines

Striker Felts

The recent installation of a press pilot unit has allowed Binet to develop a new felt generation named STRIKER. This new concept felt has been deeply tested up to 2,100 m/mt in order to measure the felt behaviour, mechanical changes during its use and above all, to minimize the water carrying and to maximize the effectiveness of the conditioning equipment. Mechanical conditioning and water removal with different vacuum levels and at different air temperatures have been monitored, checked at different stages of felt life and for different combinations of base and batt architecture.
The pilot units’ data has scaled up to the FELT ENGINEERING to optimize the felt design and to produce a number of industrial test felts that are completing their life cycles in different tissue machines with a speed range of1,100-1,700 m/min. The results on the tissue machines are very positive with dryness of approx. 45-46% with single presses, and we could suppose above 48% on the double press machines.
The next step will be to apply our SOFT-TOP and TWIN-TOP technology on our STRIKER FELTS to improve an additional 1-2% of the sheet dryness and so to offer to the tissue sector the opportunity to obtain the same dryness of a shoe-press with only a very special felt.

First Industrial Results

On one YPU machine at 1,100 m/min, saving of 14,000 m3 of gas per month (1.5 times the price of the felt), very regular vacuum stable under 0.5 bars, very good pick-up, no problem of any type, lower water carrying, about 200 gsm vs. standard felts. On one YCF machine at 1,700 m/min reduction of hood temperature of 33%, reduction of 25% of vacuum power, better lifetime, lower water carrying about 250 gsm vs. standard felts. On one YCF machine at 1,450 m/min increasing of dryness from 41% to 45% on single press. Very good profile, lower water carrying, about 200 gsm vs standard felts. No problems at all.