18 HEIMBACH


Pulp Paper & Logistics


Efficiency in the dryer section


A number of projects carried out by Heimbach’s TASK-Force illustrate the potential for making cost savings and improving productivity by using pocket ventilation. PPL reports


making line the focus often tends to shift to the dryer section. Nearly 65 per cent of total energy demand comes from the drying process. This makes it imperative that, for


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example, air inflow and outflow are accurate in the hood, as this is where analysis can often highlight bottlenecks or areas for improvement.


This is one measure among


many that helps papermakers not only save costs, but also increases productivity. All of this relies heavily on a fine-tuned dryer section.


In this article, Heimbach TASK-


Force offers some guidance on pocket ventilation which, approached correctly, will reap considerable rewards. The first case study is about a


customer that produces newsprint in the range of 40 to 60 g/sqm at 1,000 metres per minute. The machine has been regularly measured and successively optimised by Heimbach TASK for an extensive period of time.


Lasting improvement On the basis of measurements made, a step-by-step restructuring of the dryer section from conventional to slalom was recommended. This was tackled over the following few years; first the third, then the fourth dryer group (groups one and two were already running as a slalom). The first success yielded was


January/February 2019 Figure 1: Unfavourable – “undercurrent”


clearly improved runnability and visibly fewer sheet breaks at the same production speed as before. Thomas Fischer, leader of TASK, summarises it aptly: “More productivity, more quality, more efficiency.” However, this was not the end of the optimisation plan as the air inflow was still directed into


the basement as “undercurrent” (Figure 1). This means it flows past the machine but does not contribute to the drying process.


Blow pipes showing the way Consequently the drying performance was still not sufficient in the production of heavier grades (60 g/sqm) at


maximum speed. In this case the path to a solution was the use of blow pipes, which significantly improved drying capacity. Blow pipes are built into the cylinder pockets, which in many cases mean both higher productivity and energy savings per ton of paper – one measure, two benefits. This


henever energy savings are discussed in relation to a paper


Figure 2: Very good – blow pipes distribute air in a sensible and directed way


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