Paper Technology International 2024 - Journal - Page 146
PAPERTECHNOLOGYINTERNATIONAL
Parallel pumping of stock from the conical section of a storage
tower
This application allows the simultaneous pumping of pulp
from the storage tower to two or more locations. From the conical
section of the tower, the pulp is transferred into the feed chute and
pumped by the MCE pump at medium consistency to the following
stage in the process. At the same time, pulp is being diluted through
the lower section of the storage tower and pumped further to the
desired location at low consistency. White water from the paper
machine can be segregated and two or more paper machines can
be fed from one common storage tower.
Examples of problems in storage towers
When a storage tower is charged through the roof in the
conventional way, channeling can easily occur with stagnant areas
developing in the storage zone. The active storage capacity of the
tower is, therefore, reduced. Furthermore, severe uncontrollable
consistency variations can result from lumps of high-consistency
stock working loose from the stagnant zone and falling into the
agitation zone. In addition, air is entrained into the stock in the
conventional charging method.
In certain towers in pulp and paper mills, only some of the
storage capacity is utilized. The broke tower is a typical example,
with the broke being dropped down to the bottom. Additionally, a
stagnant zone develops in the areas around the fast-昀氀owing zone in
the middle. Air is entrained into the stock.
Solutions to your storage tower problems
SALOMIX® TES top entry spreader
TES spreads stock evenly on the top surface to control the
昀氀ow in the upper medium-consistency or high-consistency part of
the tower. The quality of the discharged stock remains good.
TES solves problems with retention time
A mill had problems with a 2’000 m3 storage tower, the
upper diameter of which is 12 meters, and the bottom diameter 6.5
meter. The theoretical retention time of the tower is approximately
4 hours with a full stock level. The actual retention time before the
installation of TES was less than 2 hours. Test run results show
clearly how TES helps the tower to operate with the correct retention
time:
Tower level
89%
59%
Measured average retention time
4 h 10 min 2 h 10 min
Theoretical retention time
4 h 24 min 2 h 16 min
TES solves problems with entrained air
A mill had problems with the air content of pulp in its storage
tower. Before TES was installed, the air content was 昀氀uctuating
badly and averaging 6% (blue curve in the 昀椀gure). After the
installation of TES, the air content decreased to 2% and the variation
was markedly reduced, as shown by the red curve.
Figure 15: Air content 昀氀uctuation by the tower discharge pump
before and after the installation of top entry spreader.
Figure 13: MC parallel pumping system arrangement..
Figure 14: MC parallel pumping process application.
146
SALOMIX® GLI
GLI is a special center 昀椀llet located at the bottom of the
storage tower. GLI enables the trouble-free operation of mediumconsistency and high-consistency storage and bleaching towers
with a large bottom zone using several agitators.
GLI bene昀椀ts
GLI with dilution baf昀氀es is used to create a well-controlled
mixing/dilution zone at the bottom of the tower.
GLI effectively separates the tower’s storage zone from the
active mixing and dilution zone, thus providing a powerful tool for
ensuring an even discharge consistency and good operation of the
tower. More than 100 MC and HC storage towers around the world
are operating with the help of GLI.
SALOMIX® VULCA
VULCA is another type of center 昀椀llet pillar that is also
located at the tower bottom. The 昀椀lling and pumping of stock are
carried out through VULCA.
