I thought that when I brought up steel dryers last week, it would be just a mild reminder of this very important opportunity. Here is what we received on the subject:
Of course, steel makes more sense for pressure vessel construction than cast iron.
The existence of sunk investment in foundries is perhaps a driving force in retaining the Victorian technology, but I suspect that the key driving force is that the greatest enemy of almost any new technology is the expert in the old.
It is not easy to make a good cast iron pressure vessel, particularly when it must function as a dryer, and perhaps even provide special effects, such as a Yankee. When Chief Engineer Joe has spent 20 years learning all the tricks, he hates, sub-consciously, to see his know-how become obsolete, so he develops 999 reasons to improve the cast iron drum incrementally, instead of jumping ahead.
Our industry is full of such situations, which is one reason the younger South American mills are wiping us out.
Funny you should mention this now. We and our clients (2), had the same conversation with a couple of suppliers last week and you are correct in your assumption of a vested interest in some companies to stay with castings. When the question is posed "Can you make steel dryers?" the answer is, "We don't do that". The old rhetoric about quality, safety and other negatives has disappeared from their vocabulary. Besides which, the number of large cylinder casting facilities has dwindled down to 2 with the closure of the PMP (old Beloit Walmsley UK facility).
One other advantage for steel is a shorter delivery time now that manufacturing techniques have been refined. Chopping two months off a machine delivery has a huge impact on financing costs for a tissue machine project. The excuses for staying with cast iron have disappeared and instead have been replaced with excuses for NOT going to steel dryers.
I would like to confirm that our company has successfully supplied steel dryers for new paper machines and for paper machine rebuilding.
We confirm that you have a better heat transfer but also you have to consider that a steel dryer keeping the same total face will offer 200-300 mm wider evenly-heated surface....
Till today we have supplied 61 dryer cylinders and 2 Yankee cylinders.
De Iulius C. & A.
Thank you Mauro, last week we also mentioned Toscotec and Andritz.
Folks, it looks like we are winning the steel dryer can war. Keep the pressure up!
Any more comments on steel dryers before we move on?