12 HEIMBACH
Pulp Paper & Logistics
Energy savings in the press section
for packaging grades Opportunities for energy savings in the press dewatering process and in press clothing are possible. Olli Kääpä details two case studies and indirect collateral factors
constructions. Atromaxx press felts are manufactured on a modular basis with their base units composed of either woven and/or compound modules that are aligned multi-axially to one another.
T The design of the individual base
and surface batt modules and their combinations with one another (Figures 1 and 2) create the variety of performance characteristics of the whole felt. The degree of batt and base
capillarity and thereby the initiation of water flow from the sheet (Figure 3), the amount of void volume, the level of permeability and also the amount of compressibility of batt and/ or base to provide resilience. Consequently, Heimbach believes
Figure 1: ATROMAXX.M
that Atromaxx can truly be described as multi-talented. An example is with basis weight and speed change. For the retention of a high dewatering efficiency it may be necessary to make a significant adjustment in the relationship between uhle-box and nip dewatering. By establishing the required characteristics in advance, a
multi-axial felt from Heimbach can be made to perform either for predominantly uhle- box dewatering or also for predominantly nip dewatering. There is a dogma in the industry which promotes the maximum ultilidation of felts, but does it have unlimited validity? Clearly, maximising the life of felts is important on a paper
making line. It is initially at least the best way of keeping down costs. But is it really worth while to run a felt to its absolute limit, or even beyond? In most cases it is not. Towards the end of a felt’s life the break frequency increases as the felt is often worn down to the base weave. With reducing dewatering efficiency the paper leaves the press with a lower dry content, the risk of breaks increase dramatically and steam consumption rises excessively.
Case study: a testliner machine
Figure 2: ATROMAXX September 2012
On this machine with a width of 8-metres and running at 1,250 metres per minute, the press felts were used to their limit, being changed every eight weeks. Costs for the clothing and necessary shut downs amount to €1 million per year. With an average break rate of 60 per month (which is equivalent to 720 per year, each
he key feature of the multi-axial press felt range from Heimbach lies in its wide range of
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