A.Celli EvoLock®: the innovative solution to improve the performance and reduce the inspections of a Yankee Dryer

Thanks to the continuous efforts in the field of research and development, A.Celli is proud to present the evolution of the Yankee Dryer with forged shell, the iDEAL® EvoLock®: a solution that will allow you to minimize the costs related to inspection operations without sacrificing quality and safety.

author: A.Celli Group

Industry Insight by:

A.Celli Paper S.p.A.

iDEAL® EvoLock® Yankee Dryer

Our new EvoLock® solution, starting from the excellent technological base of our Yankee Dryer Forged® YD, includes all the A.Celli technologies already known and appreciated, like the use of a monobloc shell forged from a single steel ingot. The novelty lies in a unique and highly innovative head-to-shell connection system, which does not require the use of structural welds or bolts. This solution allows, from an engineering point of view, to minimize the deformation of the shell edges induced by the deformation of the heads, which in itself is caused by the internal steam pressure. This important feature improves the runnability on sheet edges and consequently the efficiency of the machine.

The special design also allows to reduce the overall width of the shell, giving you the capability of drying a larger format sheet with the same existing machine gauge and, as we will analyze in the next paragraphs, to reduce the necessary inspection interventions.

Required inspections: comparison between EvoLock® and other steel Yankee Dryers

For our analysis, we will consider two types of steel Yankee Dryer on the market:

  1. A traditional Yankee Dryer with welded shell and shell connected to the heads by means of full penetration structural welds.
  2. The new A.Celli iDEAL® EvoLock® solution, with forged shell and a new head-to-shell connection system who does not require bolts nor welds.

The following table compares the types of the required checks for the aforementioned Yankee Dryers during the first 12 years of life.

Required checks in the first 12 years
Tab. 1: required checks in the first 12 years.
total downtime during the first 12 years
Tab 2: total downtime during the first 12 years.

The evolution of the Yankee Dryer: less inspections, more productivity

A.Celli iDEAL EvoLock
The new A.Celli iDEAL® EvoLock®

From the table we can see how, for typical welded Yankees, the combination of periodic weld inspections and regular internal inspections recommended every 2 years leads to a tight schedule of invasive, expensive and prolonged checks compared to those required for the A.Celli iDEAL® EvoLock® Yankee Dryers. The greatest impact of these interventions is due to the need to completely cool the cylinders for the inspection of the internal welds. As for the Yankee Dryers of the iDEAL® product family, the staff will have to access them only for the biennial visual inspections typical of all Yankees, while the ultrasound tests are prescribed only for the structural screws which are all located on the outside, and therefore do not require the complete cooling of the cylinder. In the table, we will associate the different types of inspection and their respective intervals with the typical times necessary for their execution to calculate the total downtime of the Yankee cylinders during the first 12 years of life.

In conclusion, the results clearly show the advantage of A.Celli’s new EvoLock® Yankee Dryer which, compared to conventional solutions, is unmatched in terms of time and costs saved on periodic inspections.

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