It is an unresolved and annoying problem that especially polymer solutions with higher viscosity cannot be added homogeneously. To achieve the best possible homogeneity large amounts of dilution water must be added and the stock and sludge lines are furnished with lances or other structures. There are various approaches to solve this problem, but for larger tube diameters the insertion of mechanical elements seems to be unavoidable.

In continuous operation they often cause deposits and the attendant well-known problems. Even if you accept these problems usually the polymers cannot be mixed in completely homogeneous, which leads to yield losses. Due to their large chain lengths polymers must be treated by the shear forces as gently as possible to be fully effective.

Therefore a metering station mounted before sifters or pumps leads to a satisfactory mixing, but as polymer chains are shortened, efficiency is lost and a higher dosage is necessary.

It is always a compromise between dosing before the last shear point with the consequence to obtain optimal mixing and accept higher dosages, or dosing after the last shearpoint with lower dosages and the risk of a problematic inhomogeneous mixing in larger pipe diameters. I stress – it was a compromise, because with the new ecowirl technology it is now a thing of the past.

Without any mechanical parts in the pipes single-acting nozzles, which are easily maintained, swirl the polymer solution gentle and absolutely homogeneous through the whole pipe. The result is a uniform distribution with almost 100% polymer efficiency.

The ecowirl, which is based on a high sophisticated unique high-tech dosing technology, has already achieved remarkable successes in many operations in practice.

Users report significant technical improvements in the cross-sections, better runnability and various quality improvements combined with a reduction of polymer consumption of up to 25%.

We are very pleased that we have found the ecowirl, and that we are allowed to offer this revolutionary technology to our customers and to integrate it into our numerous projects.

Text: Manfred Zabl

 A REVOLUTIONARY WHIRL IN DOSING TECHNOLOGY

 The picture (beside) shows multidimensional condensation vortex fields produced by a plane, which create impressive spacious effects. One sees that the rotary axes of the main vortexes are perpendicular to the micro vertexes.

The new mixing system, ecowirl m produces a similar vortex field to blend additives efficiently into large volume flows.

The whirl generated at the exit looks like a twisted rope. It is the combination of a large vortex motion with many small microvortices

(= the twisted rope with braids) perpendicular to them. This process is initiated by a motive fluid with a speed of 6 m³/h and about 3 kg/h polyelectrolyte can be added. For larger quantities various complete solutions are available.

The real innovation of ecowirl is that additives with a high solid content can be added directly. Usually, mixing operations with a mixing ratio of more than 1:500 cannot be carried out in one step. With ecowirl mixing operations with a mixing ratio of 1:100.000

can be carried out in a single step with a high uniformity. Therefore, reactions with the pre-dilution water that tend to reduce the effectiveness of the additive can be excluded. Moreover, it reduces the required equipment.

The ecowirl m essentially consists of four main components, which are firmly clamped together: injector, engine, turbo and diffusor. The rotary motion is carried out by the fluid only. The four components separate the preparation area, the premixing area and the main flow mixing area from each other. In the preparation area the specific surface area of the process water is increased and vortexforces are generated. In the premixing area the additive is injected counter currently, the microvortices rub against each other that causes extremely high contact rates. Also an important factor for chemical reactions is temperature; therefore normally warm process water is used. The ecowirl m has already proven highly efficient and easily meets requirements which currently available systems do not meet. How is that possible?

This diagram shows the usual requirements of an operator for a dosing unit. The complete system, from the commercial product up to the injection into the main flow, should be the perfect system, here termed as “Bluechip”. The following parameters are essential for performance and reliability: low effort, cleanliness in dosing, easy operation, cost-effective yield of additive, only one mixing process, loss of energy, recycling und payback. The ecowirl meets the “Bluechip” requirements to a large extent and sets new standards in handling, economy and ecology.

Future applications

 Ecowirl technology has proved in tests that it is able to add sophisticated additives like retention agents (after sorting and ahead of the head box of the paper machine) without problems. The successes already achieved are an incentive to revolutionize with this system step-by-step a variety of dosing units. With this mixing technology, mixing rates up to 1:100.000, with a solid content up to 50% in 500 milliseconds can be achieved.

This reactivity matches the modern process technology. The ecowirl m can be operated with thin stock, head stock dilution water, clear and fresh water.

Usually process water is used to avoid heat losses in the production, to raise the circuit temperature of the white water and to support the mixing process by the supply of heat. Further applications on the paper production line have to be checked; the fresh-and waste water treatment in the production area remain interesting.

In the beginning, polymers and bentonites
were the first pillars of the newly founded
ACAT. But soon the question arose, wouldn’t it
make strategic sense to combine the long experience and knowledge of our employees in
paper production and the environmental sector with the corresponding system technology,
to offer customers complete solutions ?. The
combination of systems engineering and
chemical products, together with the expertise
and experience of our employees should lead
to very good results. And it was just as expected!
First, larger plants were provided or bought
from our former supplier “Allied Colloids”, but
soon our employees took the first steps in
stand-alone construction of smaller units in
backyards and garages. The pioneering work in
this field was performed by our „veteran” in
plant construction par excellence, Bernhard
Anzenberger, together with the active support
of the Heads of Departments of Paper and
Environment Technology, Theo Weinbrenner
and Erich Sailer.
In 1998, the targeted expansion of the ACAT
marketing activities in machinery and plant
engineering resulted in the establishment of a
new department. Two years later we bought
the engineering and logistics centre in
Scheibbs NÖ and adapted it.
In addition to the logistics our polymerdissolution stations and our bentonite systems
with the associated switch cabinets,
were manufactured in Scheibbs. The great advantage of our small production plant is to
meet special customer needs and to fulfil most
wishes based on the existing technology.
“The strength of our team
is to meet special customers’ needs and to fulfil almost every wish on the
basis of the existing technology.”

INDIVIDUAL AND FULLY DEVELOPED:
ACAT Bentonite & Polymer Systems

AUTHOR: THEO WEINBRENNER JUN. Article from: inside acat 11/2010, pagee 2 of 4
Polymer Systems in Jet-Wet-and in dispersing
technology and for liquid polymer systems
In general polymer systems are distinguished
with regard to the dissolving technique used.
There are the two techniques, the jet-wet and
the dispersion technique. To eliminate unnecessary sources of error sequence and structure, the systems are kept as simple as possible. Therefore chosen control systems Siemens
LOGO or Moeller Titan are completely sufficient. On request PLC systems can also be installed but they are not really necessary. For
the integration into a DCS system, these systems are supplied without any control.
Polymer systems as well as bentonite systems
are designed for a continuous 24-hour operation.
Wetting quality of powdered polymers
is decisive
The difference between the two polymer
powder systems is the wetting of the polymer.
In the case of dispersing technique the powder
is conveyed via a screw directly into the disperser and is wetted with water. The powder is
dissolved by stirring in the container. This
method is often used in municipal wastewater
treatment plants.

INDIVIDUAL AND FULLY DEVELOPED:
ACAT Bentonite & Polymer Systems

AUTHOR: THEO WEINBRENNER JUN. Article from: inside acat 11/2010, pagee 3 of 4
Polyelectrolyte solutions in paper mills are of a
very high standard. Mostly the „Mercedes” the
JetWet system is used there. The powder polymer is conveyed with a screw into a venturi
tube and then blown with a fan into the head
of the JetWet. The fine distribution of the
powder ensures a better and more effective
wetting in the JetWet head. Larger amounts of
polyelectrolyte solution can be prepared. In
disperser technique they are limited.
In both systems the necessary dwell time is
achieved in a storage tank. With the help of a
transfer pump the polyelectrolyte solution is
pumped from the dissolution tank into the
storage tank.
We also provide systems for liquid polymers.
In a pot with a rapid stirrer the liquid polymer
is mixed with water. If this pot is full, the solution will run into a storage tank.
This system is also available in different sizes.
In all systems a maximum concentration of the
polymer solution of about 1.0 percent has to
be observed. Both small and big bag handling
systems are
ACAT-bentonite systems in two sizes
The Bentonite systems (SlurryJet™ ABA) are
based on a continuous flow system. The preparation of the bentonite slurry is ensured by a
system with different agitators. The maximum
concentration of the slurry is four percent.
ACAT offers two sizes depending on production quantity.
The SlurryJet ™ ABA with an output up to 7000
litres / h slurry has a 3-chamber continuous
flow system with four special agitators. The
bentonite is transported into the agitation
chamber with a screw. The „little brother” of
the SlurryJet ™, the SlurryJet ™ Small with a
capacity up to 2500 l / h slurry has a twochamber system equipped with two agitators.
Details can be designed on customer request.
The SlurryJet ® Small has a capacity
up to 2500 l / h slurry and a twochamber system equipped with two
agitators.

INDIVIDUAL AND FULLY DEVELOPED:
ACAT Bentonite & Polymer Systems

AUTHOR: THEO WEINBRENNER JUN. Article from: inside acat 11/2010, pagee 4 of 4
For the polymer and bentonite processing
plants special dosing systems can be offered
providing dilution to the desired polymer /
bentonite concentration and easy dosing. Especially in this sector there are possibilities,
which recently are at the planning stage. Some
of them have been realized in pilot projects
and trials were carried out together with customers.
Our excellent team, consisting of „old hands”,
who have dealt with these techniques for over
25 years and of young engineers who will help
to develop innovative systems for the future.
The strength of this team is the development
of individual customer specific solutions. For
more detailed information please contact our
sales and systems engineers