Tissue360 - Spring/Summer 2017 - 25
Global Survey Shows Trends in
Yankee Dryer Deliveries
Study of yankee dryers examines the number of operating
cylinders, tissue manufacturing growth worldwide,
as well as market changes in shell material
Typical tissue paper machine: Tissue sheet travels from
left to right (wet end to dry end), then is creped off of the
yankee dryer and wound into a "parent roll" for converting
into consumer products. Photo courtesy Andritz.
To assist the TAPPI Yankee Dryer Safety & Reliability Committee
in understanding issues in the tissue business, we periodically assess
the global deliveries of yankee dryer cylinders, which are an integral
component of tissue machines.
A typical tissue machine starts with water at the wet end of the
machine. A small fraction of pulp fibers is mixed into the water, which
is then pumped through a headbox onto a forming fabric or belt. This
belt goes through various zones of vacuum and pressing to dewater the
solution to form a paper sheet. The final amount of dryness (or water)
is controlled by the "dry end" of the tissue paper machine.
The yankee dryer and the hot air hood (cap) are the last components
that the tissue paper sees before it is creped and wound into a large tissue
roll typically called a parent roll. The tissue parent rolls are taken to
warehouse storage for converting (transforming) into finished products
such as toilet tissue, facial tissue, kitchen towels, napkins, etc.
This is the most recent update to the global survey. Data is presented
in words and graphs that demonstrate trends in the global use of yankee
dryer cylinders for tissue production. Conclusions that can be inferred
from the data are the number of operating yankee dryer cylinders
(globally and by regions), tissue manufacturing growth (globally and
by regions), as well as market changes in yankee dryer shell material.
Data was obtained from participating yankee dryer manufacturers
in Europe, South America, and Asia and sorted by destination country,
year of delivery, and yankee dryer metrics such as shell outside diameter
and shell face length. Yankee dryer shell material was also noted and
sorted. Since 2000, there have been increases in the supply of yankee
dryers with welded steel shells and components (sometimes referred to
as a steel yankee dryer or SYD).
Yankee dryer cylinders that are constructed from gray cast iron or
welded steel have some similarities. The shell inner surface is grooved
(sometimes called ribbed) for improved heat transfer. To ensure accurate
machining of the shell inner and outer surface, there must be access to
these surfaces by use of either a horizontal lathe or a vertical boring mill
to groove the inside surface and to finish machine (crown) the outer
papermaking surface. Yankee dryers constructed from welded steel shells
have fewer high-strength steel bolting, usually at the head-to-journal
joints. The steel welds are in the shell sections and at the head-to-shell
joints. Internal access via accessway openings permits maintenance and
adjustment of the internal steam distribution system and the condensate
removal system (similar to the access for gray cast iron yankee dryers).
Not all deliveries have been listed during this time period of 1971-2015;
some were missed, as not all global yankee manufacturers participated
Yankee dryer cylinder constructed from gray cast iron shell and
components. Note the high-strength steel bolting at the head-to-shell joints
and at the head-to-journal joints. Photo courtesy Valmet.
Tissue360º SPRING/ SUMMER 2017