Pulp Paper & Logistics
HEIMBACH 13
Figure 3: ATROMAXX: Initial water flow sheet - pick-up felt
break taking 15 min at €10,000 per hour downtime) about €1.75 million per year must be added. The total cost for felts, felt changing and downtime through breaks is €2.75 million per year (Figure 4A). If we now consider the situation
where the life of a set of felts is reduced to six weeks, more felts and felt changes will be necessary (costing about €1.33 million per year). However, in this case the break frequency will be reduced from about 60 to about 50 per month – by installing multi-axial ‘specialist’ felts from Heimbach, and by way of an example obtaining a higher dry content by increased nip dewatering. The break costs are reduced (about 580 breaks per year, each 15 minutes at €10,000 per hour downtime) to about €1.45 million per year. This means that with a life of only six weeks per set of felts the total costs for felts, felt changes and downtime for breaks amount to €2.78 million per year. Therefore the additional cost of a six-week rather than an eight- week life per set of felts is just €30,000 per year (Figure 4B). This additional cost is significantly more than compensated by a number of additional positive factors. Because of the shorter felt lives
the downtime for 120 breaks per year is eliminated. The result is increased production time of 30 hours per year. The sales value of the increased production provides a bonus of about €690,000 per year (Figure 5). With the installation of Heimbach multi-axial felts, which as a rule provide better start-up characteristics, further additional production can be achieved. For example, an increased start-up speed of 50 m/min for one day following every felt change has a value of about €210,000 per year. Furthermore, a figure of €30,000
per year can be added for the energy saved – as a result of lower uhle-box vacuum – combined with reduced steam consumption resulting from higher total dewatering and the higher dry content after the
3.press. The final result – after
subtracting the €30,000 additional cost of changing from eight week felt life to six week felt life (Figure 4B) – is an increased profit of about €900,000 per year (Figure 5) – less the materials and operational cost of the increased production. To return to the initial question of ‘maximum felt utilization – or not’, despite the planned reduction of felt life from eight to
Figures 4a and 4b: Cost comparison: Life reduction
six weeks, process optimisation can be achieved with the help of high performance multi-axial felts – and additionally both a reduction in costs and an increase in production with significant increase in profits.
Advantages for the Energy Balance Production time gained is equivalent to 30 hours per year more energy utilisation of heated dryer cylinders, increased production worth €690,000 per year, plus each start-up for one day at 50 m/min faster which is equal to annual increased production worth €210,000 plus full year reduction of vacuum and steam consumption is equivalent to about €30,000.
Case study: packaging grades In this case the location on the line is the
3.Press Bottom Felt (Shoe Press) and the requirement was for energy saving whilst retaining the effectiveness of the machine. Under measurement supervision
from Heimbach during a short break, both bottom felt uhle- boxes were lowered. A multi-axial
felt from Heimbach was already running in this location. As a result of measurements taken after lowering the boxes and further measurements a week later the decision was taken to operate without the boxes. With further Atromaxx.M
bottom felts (Figure 1) the machine operated for the remaining 217 days of the year ran uninterrupted without the two uhle boxes. At a normal pump power consumption of 190 kW a substantial saving of energy and energy costs could be made – quantified in Figure 6 – without any deterioration in machine performance or paper quality. Runnability without uhle boxes in this
3.Press could be maintained over the whole life without any reduction of the dewatering performance. This was only possible because the multi-axial felts were able by increasing nip dewatering to more than compensate for their removal.
A further advantage of uhle-box
removal was the elimination of the braking effect on the felts over the uhle-box slots. This brought with
4 September 2012
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36