Mixing- and reaction Technology - european-coatings.com€¦ · dimensioning and geometric design of mixer ... ce homogeneity. ... to element dia.), thus no formation of dead zones

Static Mixing- and Reaction Technology

Heat exchangers for viscous fluids

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AGENS Stratmann GmbH - Auf der Brede 16 - 59302 Oelde - www.agens-stratmann.com Tel.: ++ 49/ 0) 25 22/ 93 75 29 - Fax.: ++ 49/ 0) 25 22/ 93 75 29 - Email: [email protected] Page 2 of 8 © Copyright 2009 AGENS Stratmann GmbH

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Static Mixers Static mixers are devices which make use of fluid dynamics to carry out process operations without moving parts. As a rule, they involve structures with a special geometry that are built into pipes or channels. The goal of AGENS Stratmann GmbH is the dimensioning and geometric design of mixer structures for optimal process control. The following basic operations can be performed for soluble or insoluble fluids: Soluble Fluids

• Mixing, homogenization • Reaction processes • Pulverization, evaporation

Insoluble Fluids • Dispersion • Emulsification • Aeration, bonding • Reaction processes • Material exchange

When first selecting the correct mixer structure, the most important factor is the dimensionless Reynolds number as applied to the hydraulic diameter of the built-in components. The Reynolds gives a measure of the ratio of iner-tial to viscous forces and consequently quanti-fies the relative importance of these two types of forces for given flow conditions.

This can be calculated as follows:

Re = ρ = Density of mixture [kg/m3] v = Flow rate [m/s] εv = Empty volume fraction [ > 90 %] dh = Hydr. diameter [ ~ 0,2 - 0,5 D] η = Viscosity of mixture [Pa s] D = Pipe inner diameter [m] Additional Selection Criteria:

• Density difference of fluids • Viscosity difference of fluids • Process conditions • Physical and chemical fluid properties • Structural conditions

Years of experience are needed to produce the best possible design. Several basic factors in addition to pure hydraulics must be taken into account for proper dimensioning. The knowledge and experience of AGENS Stratmann GmbH will guarantee a significant competitive advantage for our customers.

ρ (v/εv) dh η

The following table shows an initial overview of the most important mixer geometries and their properties:

• Re minimum 2300 (turbulent) • Highest mixing efficiency • Positive mixing structure

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• Re minimum 4000 (turbulent) • Resistant to solid material • Low pressure loss

• Re minimum 6000 (turbulent) • Economically priced • Impulse mixing structure

• Re less than 20 (laminar) • High-low viscosity mixing • Highest mixing efficiency

• Re minimum 2300 (turbulent) • Adjustable hydr. diameter • Calculable droplet or bubble dia.

• Re less than 100 (laminar) • Calculable droplet or bubble dia. • Positive mixing structure

The structures AGENS AMV, AMX and AMW have a scale-up design. Test results at the pilot plant scale can be directly transferred to the appropriate operational facility.

Fluid Name Properties

AGENS AMV

AGENS AMW

AGENS AMX-3

AGENS AMX

AGENS AMV

AGENS AMX


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Homogenization of Soluble Fluids with Turbulent Flow.

Static Mixer AGENS AMV In an AGENS AMV Mixer, the incoming flow currents are additionally divided into individual partial flow currents and then sheared off at the junction area of the channels. This method of controlled division and displacement allows the AGENS AMV to be insusceptible to flow rate fluctuations. In addition to the rearrangement of partial flow currents, vortex displacement aids in the homogenization of the mixture media in the built-in components. It achieves a continous self-controlled process at start up and shut down phases with always the same homogeneity.

Advantages of the AGENS AMV • Highest mixing efficiency with regard to installation vo-

lume • Insusceptible to flow rate fluctuations • Special feeding lances allow for the smallest installation

length • Scale up possibility 1:100

Selected Applications • Dosing of additives • Mixing of process gases in facili-

ties for manufacturing acrylic, nitric, and sulfuric acids, vinyl chloride, ethylene oxide or me-thanol

• Evaporation of liquids • Regulation of neutralization or pH

value • Blending of gasoline, diesel or

lubricants • Mixing of ammonia in flue gas for

denitrification

Static Mixer AGENS AMW The static mixer AGENS AMW generates rotati-on vortices in the individual coils, which produ-ce homogeneity. It is suitable for simple mixer applications and has preferred application in the food industry. Its simple geometry can be made non-porous with an ETFE coating. In this design, it is excep-tionally suitable for sulfuric acid dilution at high operating temperatures.

Static Mixer AGENS AMX-3 The AGENS AMX-3 generates counter-directional rotation vortices. It is suitable for the simplest mixing applications, and its very reasonable price-performance ratio makes it particularly attractive. This mixer geometry can also be coated with ETFE to guarantee a long service life even with the use of aggressive media.


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Dispersion of Insoluble Fluids with Turbulent Flow

The AGENS AMV geometry can be realized in a wide variety of reactor types. The type spectrum ranges from small static mixers DN 25 to large pipe reactors. The following example illustrates a slow-moving 2-phase reaction in a 140 m long pipe reactor. The dimensioning of this reactor is based on pilot plant tests.

Additional Typical Applications

• Hydrocarbon neutralization • Phosgenation of bisphenol • Chlorination, hydrogenation • Air, CO2 or ozone in drinking water

• Masstransfer can be calculated • Reliable scale-up from pilot plant station

to operating dimensions

The AGENS AMV Mixer bonds insoluble fluids to each other in a continous current. The disperse phase leaves the mixer as a droplet or bubble cluster. The smaller the generated droplets or bubbles, the larger the interphase boundary. The hydraulic diameter of the built-in compo-nents thus has high significance. Advantages of the AGENS AMV structure

• The hydraulic diameter can be precisely adjusted by determining the number of layers (see image below).

• The bubble or droplet diameter can be calculated

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Homogenization and Dispersion with Laminary Flow

Static Mixer AGENS AMX The AGENS AMX Mixer consists of a structure of crossing webs. The mixing action results from continuous division and repea-ted recombination of the indi-vidual layers.

Each mixer element is installed at a 90° offset, in order to generate mixing action over the entire pipe diameter. Its high mixing efficiency allows the device to process the smallest mixture volumes.

Advantages of the AGENS AMX • The AGENS AMX with 8 bars is the

most efficient geometry for the mixing of high- and low-viscosity media

• Short residence time spectrum for precise shear entry, thus exceptionally suitable for tubular reactors

• Reliable scale-up from pilot plant station to operating dimensions

Selected Applications: • Homogenization of polymer melts before injection • M i x i n g a d d i t i v e s , o i l s , p i g m e n t s o r

inhibitors into polymer melts • Dispersion of stripping agents in polymer melts before

degassing • Mixing epoxy resins with curing agents • M i x i n g a d d i t i v e s i n p o l y o l s f o r

polyurethane manufacturing • Mixing colorants into silicone


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Static Mixers for Extrusion

The high frictional forces between the channel inner wall and the polymer flow present the main problem in the extrusion of thermoplastics. Because of these forces, the flow rate at the inner wall of the channel is practically equal to zero. In the middle of the channel, the flow rate increases correspondingly. This forms the typical laminary flow profile.

The associated diagram shows the temperature difference between the channel middle and wall for an LDPE extrusion. Differences of up to 40°C in the polymer flow can occur for an increasing flow rate. The viscosity of the melt changes in relation to the-se temperature differences, with the following pro-ductivity results: • Poor and inexact extrudates • Not possible to reproduce work results • Defective master batch distribution,

high operating costs

Solution: Static Mixer AGENS AMX - E The AGENS AMX - E combines the procedural advantages of the AMX mixer with an extremely robust construction due to the use of high-grade materials. Fundamentally, we offer our customers indi-vidual solutions. We avoid connection rods or segmentation of mixer elements. This provides the following advantages: • Thermal and product-related inhomogeneities are eliminated • Close extrudate tolerances due to homogenous polymer flow

in the mould • Optimal distribution for the master batch,

thus reduced costs for this colorant • Fundamental improvement in the mechanical properties of the

extrudate • Significant improvement in the extrudate surface

PVC or PC Polymers Susceptible to Shearing Solution: Static Mixer AGENS AMW - E We can present a solution even for polymers such as PVC which are susceptible to shearing. The AGENS AMW-E has proven its per-formance in tough applications with these polymers.

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Heating of Viscous Media with Laminary Flow

The heating of viscous media with a laminary flow is fun-damentally supported by the use of static mixer techno-logy. Viscose media form a laminary flow profile in the empty tube. This produces an almost permanent build-up on the inner side of the tube, significantly impeding heat transfer. The diagrams illustrate this process. The use of static mi-xer types AGENS AMX, AMW or AMR realize a flow cur-rent with an even temperature profile and a short resi-dence time spectrum due to the application of enfor-ced radial convection. This additional mixing effect im-proves heat transfer by a factor of 4 - 10.

Tube bundle - mixer heat exchanger with detachable AGENS AMW mixer elements for heating a polymer solution. Designed with heatable low volume heads. Nominal width DN 500, PN 80. material 1.4571/ high-carbon steel, length: 2400 mm Advantages of the AGENS AMW Mixer - Heat Exchanger • Compact design of apparatus due to

improved heat transfer (factor 4 - 10) • Due to the compact design, short residence time in

the apparatus, thus optimal product quality • Permanent equalization of inhomogeneities

(temperature), optimal product quality Properties of the AGENS AMW Mixer • Low-shearing flow due to sharp-edge design • High mechanical stability for problem-free removal

after operation • High-precision manufacturing (+/- 0.05 mm in relation

to element dia.), thus no formation of dead zones

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Cooling of Viscous Media

AGENS AMR with 2 deta-chable bundles as a silicone cooler. Designed in 1.4571, DN 400, PN 40.

Problems during cooling of viscous media in tubular heat exchangers • Differing volumetric flows in the individual pipes

(maldistribution); low cooling capacity • High pressure loss • Inflexible with regard to changing product viscosities Solution: Heat Exchanger AGENS AMR The solution is the AGENS AMR heat exchanger. The product flow is fed around the AMR bundles (connection N1, N2). The bundles are constructed of mean-dering, crossing tubes. These conduct thermal oil or water inside the heat exchanger (connection N3/ N4 or N5/ N6). No baff le plates are used, instead the AMR bundles simultaneously form the heat exchanger surfa-ce. Properties • Maldistribution can be ruled out, since there is only

one product chamber The apparatus can be ad-justed at any time for products of different viscosity

• Very short residence time spectrum makes the appa-ratus optimally suitable for polymerization reactions.

• Large heat exchanger surface (50 – 150 m2/m3) • Improvement in heat transfer

(factor 4 - 10)

AGENS AMR with 1 bundle as a polymer cooler. De-signed in 1.4571, DN 150, PN 400.

AGENS AMR with 1 bundle as a polymer cooler. Designed in 1.4571, DN 400, PN 16.

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Mixing- and reaction Technology - european-coatings.com€¦ · dimensioning and geometric design of mixer ... ce homogeneity. ... to element dia.), thus no formation of dead zones