Pulp Paper & Logistics
HEIMBACH 19
was also the outcome with the customer, though of course all the optimisations should be considered as a whole in this case. In total, the slalom conversions and blow pipe installations extended over several years.
Airflow altered and improved In the end, all pockets were equipped with blow pipes (Figure 2) which meant that the ‘undercurrent’ no longer flowed into the basement, where it is almost completely ineffective. Instead the air is directed where
it is really needed in order to remove the water vapour from the paper sheet as efficiently as possible. The optimum blowpipe position in the cylinder pockets can be seen in Figure 3. Ever since, the air has been used in a more targeted way, and the customer has also been able to produce heavier grades at 1,000 m/min. This resulted in a 17 per cent productivity increase, bearing in mind that installation costs were quite low. This is a long-term optimisation which brought the customer millions of euros of additional sales.
efficiency vary considerably in practice: “The best way to approach this,” Fisher explains, “is to look at every machine for what it is: unique.” Naturally, if every paper machine is different, the numbers will always be relative. Nevertheless, an increase in economic efficiency of 17 per cent can be said to be an impressive argument on its own.
Using blow boxes Generally, slalom groups and optimum pocket ventilation are almost always beneficial. Blow pipes are not always necessarily needed, as other techniques have been effective. Slalom group blow boxes,
Figure 3: Blow pipe located in the optimum position
Great effect Looking at the details, the customer was able to use one less dryer fabric in the third dryer group while achieving improved runnability. This was owing to, amongst other things, the reduction in sheet breaks. The same applies to the
second part of the dryer section restructuring (fourth group). If the additional turnover referred to above is calculated, it is in theory possible to add some millions of euros to the top line. However, this is not always
so straightforward, which is why calculations of economic
for example, are a sensible alternative: These are, like blow pipes, placed behind the doctor, so that the air in the pockets is distributed evenly – from the middle of the machine to both front and drive side (Figure 4). An accumulation of moisture
towards the machine centre is therefore avoided; the sheet is also better pressed to the dryer fabrics. And a stabilised sheet significantly and effectively reduces possible sheet fluttering.
4
Figure 4: Recommended air flow from the pockets January/February 2019
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