I was browsing your site when I noticed this picture
and your description of it. You aren't far off. It does
indeed rotate. But it's not a pipe.
It's a rotary dryer, used for dewatering powdered or
ground materials. It's slightly tilted, so that as it
rotates, the material can gradually roll to the far end,
from where it is carried off by conveyers. Horizontal
flues travel along the inside of the pipe, dispensing
either heated air or hot gasses evenly along the length
of the dryer. The inside of the pipe is lined with
shelves, so that as it rotates, material is carried up
and then dropped down into the hot airstream.
Normally these huge dryers are actually inside the
building, but older factories keep them outside for some
reason. They are a VERY old method of drying anything,
the first ones came into use during the 30's. So that
factory could be a lot older than it might look.
Normally they are used in plants which deal with
cement and concrete, or other aggregate based road
laying/building construction materials. I've worked in
plants which use them for drying kaolin too.
Looks like an interesting site to explore. I hope you
find the information I've given you useful. :)
Best Regards, G