Reference Manual

15−5
Figure 15-10. Fisher Vee-Ball and SKF
Actuator Basis Weight Valve
Figure 15-11. Disc Saveall
Drawing is from TAPPI’s Making Pulp and
Paper Series and is used with permission.
forming section of the paper machine and is
continually recycled back to the headbox. The
water, called white water due to its cloudy
appearance, is collected in a silo under the paper
machine. White water has fiber, fillers, and other
valuable chemicals, so it must be collected and
recycled. Most of the valuable components in the
white water are eventually retained by the sheet
forming process.
Saveall
The excess white water is sent to this device
where the fiber and fillers are removed from the
white water. A disc saveall is made up of
screen-covered segments (figure 15-11). A
vacuum is applied after the segments enter the
white water and the fibers collect in a mat on the
outside of the screen. The water that filters
through is called clear water and can be used for
Figure 15-12. Cleaner
Drawing is from TAPPI’s Making
Pulp and Paper Series and is
used with permission.
diluting water on consistency control or other
uses.
The collected fibers are washed off the segments
as they leave the white water pond. The recovered
fiber is diluted and blended with the other fiber
sources in the blend or machine chest.
Cleaners
The fibers, after being diluted by white water in the
silo, then proceed to the cleaners (figure 15-12).
Each cleaner is only capable of handling a small
portion of the total flow so many are needed for
cleaning. The stock enters the cleaner tangentially
causing the flow to form a vortex. The spinning
action causes the heavy particles to be thrown
outside the vortex. These heavy contaminants
move down the inner wall of the cleaner and are
rejected through the bottom discharge hole of the
cleaner. Lighter fibers stay near the center and
exit through the top.
Some of the good fiber is rejected through the
bottom. In order to reclaim this good fiber, the
rejects will flow from the primary to the secondary
cleaners (figure 15-13). The rejects enter a
secondary cleaner to reclaim the good fibers.
There can also be tertiary, a fourth and fifth
cleaner as well if needed (figure 15-14). Each