Sharp increase in consistency with constant production

Customized screw shaft for competitor equipment

Two identical Lamort screw presses installed in the RCF line of a French paper mill producing white testliner from 100% recycled fiber delivered a poor discharge dryness, since the compression in the press was too low. This affected the efficiency of subsequent equipment in the process. One of the screw presses has been upgraded by ANDRITZ. Comparing the modernized press with the old-fashioned "twin", the customer is more than satisfied with the results.

Comparing the "twins"

  • Outlet consistency: +8 percentage points to reach 35-40% b.d.
  • Production remained at 112.5 bdmt/d per press
  • Much better dewatering behavior compared to the second press

Do you also have an issue with low outlet consistency?

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Read the whole story ...

The challenge

A lack of discharge dryness and line efficiency were the problems with two Lamort V45 screw presses installed in parallel in a DIP line that have been in operation for more than 30 years. Each of the presses produced 112.5 bdmt per day at an outlet consistency of 32% b.d. (the feed consistency was 27% b.d.). Heavy wear of the screw and screen baskets was one of the main reasons why compression was too low. Another reason involved the existing control system, which did not allow for further adjustment of the presses. All in all, the poor dewatering performance of the presses affected the efficiency of subsequent process equipment.

After discussing our proposed solution, the customer decided to upgrade only press 1 with the aim of achieving an outlet consistency of at least 35% b.d. while maintaining the production level of 112.5 bdmt/d. This also allowed a direct comparison of the two screw presses.   

Upgrade scope

New customized screw shaft

  • Elongated shaft screen design
  • Adapted compression curve
  • High-quality wear shoes in the high- and medium-pressure zones

New set of screen baskets

  • Two new screen baskets in solid design
  • Exchangeable screen plates with straight grooves
  • Open area 14%
  • Two additional spare baskets

Counter-pressure retrofit

  • Adaption of existing counter-pressure unit

Installation and start-up were performed by the ANDRITZ service team.

Results in detail

  • The dewatering behavior of the upgraded machine is much better than before and compared to press 2.
  • The outlet consistency of 35-40% is considerably higher than for press 2 with the old screw design.
  • The production target of 112,5 bdmt/d is ensured.
  • The torque of the new design is higher at the same production as press 2 thanks to higher pressure, thus higher outlet dryness, and therefore improved dewatering.

Contact us

Are you also facing a lack of outlet dryness at your screw press?
Find out how we at ANDRITZ can help you considerably increase consistency.