Paper Technology International 2024 - Journal - Page 149
PAPERTECHNOLOGYINTERNATIONAL
Chlorine dioxide and chlorine mixing
When mixing ClO2 into the stock, a separate SX chemical
mixer is recommended. In this case the MCE pump in the stage in
question is manufactured of stainless steel. If it is necessary to mix
ClO2 into the stock as early as in the MC pump, the pump needs to
be made of titanium. This being the case, ClO2 is introduced directly
into the pump casing, to the high-pressure zone.
At the chlorination stage, when mixing both gas (Cl2) and
liquid (ClO2), one or two SX chemical mixers are used. The compact
SX chemical mixers can be installed in series and at intervals that
create appropriate retention times.
Figure 24: Oxygen, peroxide, and steam mixing
Research and development at full-scale R&D center
Research and development have top priority at Sulzer. At
the full-scale R&D center, the equipment is tested under process
conditions. Deep metallurgical know-how is also a remarkable
strength when developing equipment for these applications, where
special corrosion and wear resistance are often required. Sulzer’s
experience in and commitment to the pulp and paper industry have
made the company a leader in stock pumping, transfer, and mixing
technology.
Figure 23: ClO2 mixing with chemical mixer.
Oxygen and steam mixing with the SX chemical mixers
In the oxygen deligni昀椀cation stages, oxygen and steam are
introduced simultaneously into the steam injection pipe following the
MCE pump. No additional 昀氀ow control or instrumentation is needed
in the stock line. Oxygen can also be injected into the stock through
a separate oxygen feeder.
In the SX chemical mixer, oxygen and steam are mixed
ef昀椀ciently into the stock. A temperature increase of up to 25°C has
been reached by the SX chemical mixer. Steam consumption is
lower due to the closed and pressurized high-consistency system.
Disturbances and vibrations are eliminated by correct dimensioning
and piping arrangement and by an even and smooth steam injection.
Figure 25: (Right) MC pumping and SALOMIX™ agitator testing
at Sulzer R&D center.
CONCLUSION:
The new series of Sulzer MCE pumps reach production rates of up to 10’000 admt/d. In MC pumping applications, the consistency
and temperature ranges have been expanded to achieve the most effective conditions in a pulp and paper mill. New innovative ways to
use MC equipment are being introduced. These will reduce the investment costs when, for example, parallel tower discharge pumping or
modi昀椀ed 昀氀at bottom MC towers with a recirculation system and subsequent static DM dilution mixer system are used instead of conventional
solutions. The Sulzer SX mixer is introduced for the mixing of liquid and gaseous chemicals and steam to ensure high mixing ef昀椀ciency and
reliable mill operation. Process upgrades are available for updating earlier MC pump generations to the third-generation MCE with a high
75+% ef昀椀ciency level.
Sulzer TMS tower management systems with a TES top entry spreader, GLI and VULCA center 昀椀llet, and SALOMIX™ agitators will
help the pulp and paper mill operators to solve tower feeding and channeling problems. Sulzer’s TMS tower management system equipment
improves the stock quality and reduces the amount of entrained air in the stock, thus reducing the risk for disturbance in the process.
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