DD223642A5 - stirrer - Google Patents

Abstract

In the stirrer, the ends of the rotor spines (5 a) and the stator spines (5 b) - the spine ends are reduced to their center of gravity in spiked direction and approached as a straight - skewed to the axis of rotation (2). As a result, the mixing effect is improved in a short construction, optionally, a Foerderwirkung can be generated.

Description

Berlin, 31.7.1984

63 643/25/37

Stirring device Applicatio n of the invention

The invention relates to a stirring device, comprising in a housing a rotor with spikes and a cooperating with the rotor stator with spikes, and the use of this stirring device on special Mischproblerae.

Characteristic of the, known technical solutions

Continuous streams of viscous liquids are usually mixed in static mixers »These mixers contain no rotating parts and achieve high mixing good. But you have to accept a relatively high pressure loss and a large mixing volume. Moreover, a subsequent correction of the mixing quality is impossible during operation. When mixing high and low viscosity liquids, particularly long mixers are required Einsatz.von Rührarn or dynamic mixers warden be avoided. Bai many chemical reactions, the rapid mixing of the starting materials is very often a necessary condition for achieving the requested quality of the final product ».

In the general case, Bsi stirrers are made up of the deducted flow of a rotational, an axial, and a radial coraponant. It is distinguished zv / ischan schneilauf ends and lanasamiaufenden stirrers »

Known stirrer (Lüger, Encyclopedia of Technology (1970), Bd, 16, 417 f ") are the Schneidrührer, with him are located on the shaft in the flow direction narrow plates; the impeller stirrer - with three opposite direction of rotation in the direction of rotation; The bar stirrer or the cross bar stirrer and the finger stirrer, all of these stirrers have arms "carriers, bars, blades, etc.," which are fastened to a rotation axis which is usually coaxial to the container. In the stirrer described below, the size of these elements is not essential to the invention In general, the term spine is used for the elements attached to the axis of rotation. Similarly, in general terms, the mixing device is referred to as a spike stirrer. If necessary, the term spine is also used for the burr elements on the housing. To describe the formation of a barb, one can use the center of gravity line in the direction of the barb and approximate portions of this line by straight lines.

In stirrers or mixers known in the art, the sting (expressed by the center of gravity line defined above) initially runs radially relative to the axis of rotation, in the most cases even in a plane perpendicular to the axis of rotation. In low-speed stirrers this course is occasionally adapted to the curved shape of the container bottom. For example, in the case of the stirrer, it is known that the straight, radially extending spines do not lie in the plane perpendicular to the plane of rotation "Spikes" »The support part attached to the rotation axis runs like the anchor or

Beam stirrer radially, approximately in a plane perpendicular to the axis of rotation "On these support parts are usually several upward pointing fingers attached» The fingers - characterized by their centroid in the finger direction, practically always a straight line - are parallel to the axis of rotation, d. h., Finger and axis of rotation lie in one plane, they are not skewed to each other.

It is also known, by installing mostly mounted on the vessel wall Strorabrecher abzubfemsen the rotational flow in favor of increased radial flow, however, the mixing effect of known devices, based on the length or the energy to be expended, is not always sufficient.

In DE-OS 29 31 782 a mixing method and a device are described, in which the components to be mixed are placed on a rotating disk in a cylindrical housing and moved by centrifugal action to the outside. To increase the conveying and mixing action inclined blades are mounted on the disc. The mixture is ira substantially during the passage between the housing and the teeth on the periphery of the mixing disc "A disadvantage is that in the corners between blades and S _c Heibe at laminar flow zones of low flow velocity e-ntatehen. In addition, due to friction between the disc and the housing considerable power dissipation occurs. For applications in fiber and Photography the mixing quality is inadequate.

In DE-OS 29 09 422 a disk-shaped mixing device is described in which the successive stator and rotor disks have concentric grooves in the circumferential direction. The rings of the stator thus formed fit into the slots of the rotor and vice versa. The rings have cut-outs that run obliquely to the circumferential direction "This can be achieved at the same time a good conveying and mixing effect." The disadvantage is that between the cylindrical surfaces of the grooves and rings increased friction and the resulting heat during mixing bad from the inner mixing discs The energy dissipation is locally good, but not homogeneous over the whole mixing room-same. The effect is better in places and in places worse «

Aim of the invention

The object of the invention is to increase the utility value properties of stirring devices in a cost-effective manner.

d he rfindung E

The object of the invention is to considerably increase the mixing effect in a stirring device with simple means compared with the prior art; especially with regard to tasks, such as those required in fiber technology or z, B, in the production of photographic images »

The object is achieved according to the invention in that> the rotor spines or stator spines or both are formed

are that - if the spines are reduced to their center of gravity in the direction of the spines and approximated as straight lines - the free ends of the spines run askew to the axis of rotation.

According to the invention, furthermore, that the free ends of the rotor spines or the stator spines, or both - the spur ends are reduced to their center of gravity lines in the spiked direction and approximated as a straight line - lie in planes perpendicular to the axis of rotation and at the intersection of the free end of the spine with a radius vector an angle of , It is also according to the invention that the free ends of the spines - the spines are reduced to their spiked lines of gravity and approximated by a straight line - with their tracks in the axis of rotation and the end points of the spine containing

Layers make an angle of at least 15. According to the invention is that the rotor or Statorstacheln or both - the spines are reduced to their center of gravity line in sting direction - have a curvature * According to the invention it is advantageous that the spiked cross-section is rectangular "Furthermore, according to the invention, that rotor and Statorstacheln in Seen crossing the direction of the axis of rotation. It is also according to the invention that rotor and Statorstachelenden - are reduced to their focal points in Stachelrichtung and approximate straight - perpendicular to the axis of rotation cross * According to the invention that the stirring device as a dynamic mixer in a longitudinally flowed through the housing, preferably in laminar Ströfflungsvsrhältnissen "

is preferably also used for mixing liquids, emulsions or dispersions with high viscosity differences or in extremely unequal proportions. "Likewise, according to the invention, the stirrer is used for the purpose of moderating the temperature and improving the heat exchange.

.-. '.' , . ·

according to that the stirring device is used as a conveying member. It is also according to the invention that the stirring device is used on an extruder with the rotor connected to the head of the extruder shaft. In addition erfindungsgeraäß that the stirring device is used for mixing of color approaches in Polyacryllö.sungen, *

Due to the more intensive mixing effect, the overall length can be shortened. The stirrer is particularly suitable in the laminar flow range, especially in the case of highly viscous substances. The stirrer is particularly suitable for mixing two liquids whose viscosity differs considerably. It is also suitable when two components whose ratios are extreme are to be mixed Preparation of dispersions and emulsions »It is suitable for both continuous and batch batch grinding.

Particularly good radial mixing is achieved when rotor and stator spikes are arranged in planes normal to the axis, 3e, according to the direction of inclination of the rotor and stator spikes. in addition to the radius reactor, it is possible to achieve a radial conveying action which is directed towards the axis or away from the axis. Despite the known difficulties, that. inside the mixer on small radii the

Shear rate is low, the mixing device for 'all liquid particles creates the same conditions, by the transport from outside to inside and vice versa get liquid particles from the less effective inner area in the outer area * There is therefore no wall layer, Compared to the static mixer about the speed another degree of freedom through which the mixing effect can be influenced. In the same volume, a multiple of the mixing effect compared to static mixers can be achieved.

Because of the good radial mixing, a fairly uniform temperature can be maintained across the cross-section of the container in a vessel incorporating such a stirrer. By incorporating the agitator of the invention into a reactor for end or exothermic reactions, a close tolerance of the tolerant species in the reaction medium ^: relieved,

In mixing tasks, in which in addition to the mixing effect, one axial conveying effect is to be achieved, one can use a stirrer in which the spikes project from planes perpendicular to the axis of rotation. In crosswise (seen in the direction perpendicular to the axis of rotation) arrangement of rotor and Statorstacheln a conveying effect can be achieved. By a combination of differently inclined spines Rann in a mixing reactor locally so each mixing and conveying action can be generated.

In static mixers was observed (Chemistry Engineer Technique 51 (1979) 5, 347-364) that webs with rectangular

Cross section allow a good mixing effect. Even with the spines, this rectangular cross-sectional shape has been found to be particularly favorable. It also offers advantages in terms of production.

The invention will be explained in more detail below in several exemplary embodiments with reference to the appended drawings.

Fig. 1: a dynamic flow mixer in longitudinal section;

FIG. 2 shows a dynamic flow mixer according to FIG. 1 (section A / B) in cross section;

Fig. 3; Measurement results of standard deviations at the outlet of different erfindungsg'emäß trained mixing device; ,

4 shows another embodiment of a stirrer ira cross section;

5 shows a ring of the rotor according to FIG ^. 4, spatially illustrated.

'"'. ...; ^ represents;

Fig. 6: "a ring the housing of Figure A _{1 shown} spatially;

Fig. ' 7 .: mixing device with rotor and stator, in which

the spines seen perpendicular to the axis of rotation. cross.

In FIG. 1, in the cylindrical housing 1, the axis of rotation 2 runs coaxially. The mixing chamber 3 is sealed by the mechanical seal 4 to the outside. The spikes 5 are arranged in planes normal to the axis and are divided into rotor spines 5a and stator spikes_5b. Next, planes of spikes attached to the rotor axis and planes of spikes attached to the stationary housing 1 follow each other. The barbs attached to the housing form with the housing 1, the stator of the mixing device. By the feather key 6, the spikes are secured on the shaft against rotation. On one side of the mixing device are the inlet openings 8 for the liquids to be mixed. The outlet nozzle 9 is located at the upper end of the mixer in the cover flange 10, which is fastened with the screws 11 * The seal is made by an O-ring seal 12, on the outside of the housing 1 is the cooling jacket 13, via which the mixed heat dissipated vyerden ♦ 'Of course, the liquids to be mixed can also be heated up in this way'

Fig. 2 shows a cross section through the mixing device shown in Fig. 1. Rotor and stator spikes are set at an angle to the circumferential direction. »In addition, the dashed line and a radius vector are shown in broken lines on a spike; According to the invention, the

The spines of the rotor are tangentially attached to rings that transmit the rotational movement from the axis of rotation 2 to the spines. Due to the tangential arrangement of the spines, these have practically small radial radii

''. ' ^v . - ¹⁰ - ·

in the circumferential direction. To avoid high torque, the spikes are chamfered at their ends by a chamfer 14. By sting approach 15 areas slowly flowed through cavities, so-called dead zones are avoided. Ice Ends of the rotor spines should come as close as possible to the cylindrical shell * The same applies to the stator spikes, which should be as close as possible to the rotation axis 2 * In this embodiment of the spikes, the rotor can be pulled out of the stator. It is irrelevant to the mixing effect whether the shaft is turned clockwise or counterclockwise.

The mixing quality achieved in flow mixers, for a given geometry of the mixing device, depends on its volume V _# of speed η and flow rate V "These parameters" usually increase; the code nV / V summarized. The Endmischgüte reached can be determined by the standard deviation C of sample measurements »output standard deviation S ^ _n depends only on the throughput behaves Riis de re ingespe i st en components V and N ₀ after the loading contraction ^ ₀ = T ^v i ^V 2 ^ ^(v i ^{+ v} o ^ ^ab · The standard deviation achieved after the mixing process is preferably related to the initial standard deviation "* * Dadurch Dadurch Dadurch Dadurch Dadurch Dadurch Dadurch § § § § § § § § § § § § § § .

Experiments with glucose syrup were carried out with a mixer according to FIG. For the determination of the quality of mixing, one of the first urine nsr-9 was dyed with dyestuff. At the outlet of the mixer '-was · ^1' dye concen ration in a 1 mm specimens at various points of exit respectively

measured during a rotor revolution by the extinction of a laser beam. From these values, it is possible to determine the quotient "/ / 6 0 0. Two stirrers (a and b) according to the invention were compared with a straight (radial) spine stirrer (c) In the stirrer a), the rotor and stator sting were straight By turning the rings attached to the rotor, a stirrer b) was produced, the mixing action is independent of the direction of rotation of the stirrer Stirrer c) whose rotor and stator spines are perpendicular to the axis of rotation, the standard deviation significantly larger (Pig. 3)

Fig. 4 shows a similar mixer as Fig. I _1, however, arranged with a cross shape and approximately uniformly curved spines, For assembly of this mixer ^ is. it is expedient if rotor and stator, d. h, including the housing, are composed of rings; Each ring has a set of spikes attached. Fig. 5 shows a ring of the rotor, Fig, 6 a stator ring. In the case of a stator housing which can be divided in the longitudinal direction, it is of course possible to dispense with the annular formation.

FIG. 7 shows a mixer in which both the rotor and the stator spines ends - the spine ends are reduced in their spiked lines and approximated as straight lines - with their tracks in the axis of rotation and the end points of the spines.

Send levels make an angle of at least 15. He is, in this figure with the angle ß designated * The spikes 5 of the rotor engage in the ring spaces between the rows of stingers of the stator and vice versa. The stator is held in the cylindrical housing 1 by the grub screw 17 * In the crosswise stinger arrangement shown here and a direction of rotation of the rotor as shown, the spikes effect a transport of liquid down, By reversing the direction of rotation is in the same way the liquid upwards promoted. The drive of the rotor via the rotation axis, Z _{t performed} by the stator, is. In particular, the axial mixing of the liquid is intensified by the skewed spines. In the case of a housing through which flows in the longitudinal direction, it is often expedient to connect mixing elements according to FIG. 7 with mixing elements according to FIG. 2 in the axial direction one behind the other. This can be achieved in a mixing device simultaneously a high axial and a high radial mixing effect,. , · · ·. '.

Because of the "good" conveying effect, this embodiment, according to FIG. 7, is also particularly suitable for mixing in powders in liquids. The shear resulting from the spiked edges can be dispersed into powder agglomerates. The device has a similarity with the characteristics of screw conveyors (3, Pawlowski, The Similarity Theory in Physical Technical Research, Springer, Berlin-Heidelberg, (, 197I)), The flow behavior in laminar flow can by two ratios A and A ₂ If complete throttling is achieved, one reaches the

2 '

Delivery pressure Δ P = A ₂ / η ^ η H / D, where n means speed ',. / ^ Viscosity of the fluid, D Outer diameter of the mixing device, H the mixing length. Let the counterpressure ^ P, = 0

»3

The maximum flow rate is achieved: V = A η D, The values A ₁ = 0.32 and A ₂ = 1100 were determined for a mixing device with the following dimensions with 10 Pas of glucose syrup as the test liquid: Outer diameter of the stator D> 94 mm, gap width between rotor and stator spines S = I am, angle of a spur end with its track in the plane containing the axis of rotation and the end point of the spine ß = 45 °, with a crosswise arrangement of rotor and Statorstacheln, width of the spikes on the rotor and the stator B. = 6 mm, ticks of the spikes on the rotor and stator D = 4 mm, number of rows of spikes on the rotor n _o = 2, number of rows of spikes on the stator n _s = Z ₁ height of the rotor H-. = 30 mm, height of the stator H ₀ = 30 mm, 8 spines in each row of spikes on the rotor and stator, which is the complete characteristic of the mixing device.

P = ^Α 2 ^ Η η _ A ₂ ^ H

DA ₁ D ⁴

For a liquid with a viscosity of 50 Pas,

-1 a stirring speed of η = 2 s and a flow rate of V = 200 l / h results in a pressure of Δ Ρ = 0.31 bar. By connecting several rotor and stator combinations in series, the mixing and pressure effect can of course be increased. When connecting z, B, 5 Rotbr-stator combinations with the same geometry and the same flow rate, a pressure of Λ P = lV6 bar is created.

A particular use of the erf indungsgeniäßen agitator results in an extruder · A St AChE 1 stirrers shown in Fig. 1 or 2 au output of the extruder is fixed, and the rotor on the front end of the extruder shaft mounted ^"v It is possible without further ado to pull the entire shaft of the extruder forward because its diameter is smaller than the space occupied by the stator spines; Experimentally, this device was used in polyamide extrusion. By the stirrer, a homogenization of the temperature in the core and the outer edges is achieved. The device succeeds in "mixing low-viscosity additives into the high-viscosity perlon melt"

For the incorporation of dye mixtures (^ Ί = 0.1 - 0.5 Pas) in acrylic solution {/% - 20 - 30 Pas), a static mixer with an inside diameter of 100 mm and a length of 3 ^ 1 m has been used up to now » Spinning solution is 500 to 1200 1 / hy the Stamraansatzmenge is 1 to 5 :.% Of the solution amount, For some color mixtures, the mixing quality was found to be insufficient. Therefore, a dynamic flow mixer as shown in Fig. 1 was experimentally installed. The mixer has an effective mixing length of 380 mm and an inner diameter of 180 mm. At a speed of 50 min and a solution throughput of 1000 l / h, the mixer achieves practically the same mixing quality as the static mixer _# By adjusting the speed, z, B, to 150 rain ", a significantly higher mixing quality is achieved high Schenvirkung, favors the mixing of the low-viscosity approach quite crucial and provides sufficient

Homogeneity sure "If the added quantity of paint gets even lower and the degree of difficulty of the mixing task increases, the speed can be increased even further.

Claims (3)

E. rf claim An agitating apparatus comprising, in a housing, a spiked rotor and a spiked stator cooperating with the rotor, characterized in that the rotor spines (5a) or stator spikes (5b) or both are formed so that - the spiked ends become their center of gravity lines reduced in sting direction and approximated as degrees - the free ends of the spikes (5) run askew to the axis of rotation (2) « 2, stirring device according to point l _s characterized characterized,. that the free ends of the rotor spines (5a) or the stator spines (5b) or both are reduced in spine direction and approximate the spine ends to their perpendicular lines in planes perpendicular to the axis of rotation (2) and when cutting the free end of the spine (fig. 5) with a radius vector an angle '·: (»* ·) of at least 15 ° is formed ¹ . Stirring device according to item I ₁ , characterized in that the free ends of the spines (5) - the spine ends are reduced to their spiky center of gravity lines and approximated by a straight line with their tracks in the axis of rotation (2) and the end points of the Spiky planes forming an angle (ß) of at least 15 °. '. 4, stirring device according to one of the points i to 3, characterized in that the rotor or Statorstacheln or both - if the spines (5) are reduced to their spiky center of gravity line - they will curve. · .5. Stirring device according to one of the items 1 to 4, characterized in that the spiked cross-section is rectangular, VV Stirring device according to one of the items 1 to 5, characterized in that rotor and stator spikes cross in the direction of the axis of rotation, 7 * stirring device according to item 1 or 3, characterized in that rotor and Statorstachelenden - when the barbed ends are reduced to their focal lines in spiky direction and approximated as a straight line - seen perpendicular to the axis of rotation, 8. Use of the stirring device according to one of the points 1 to 7, characterized in that it is used as a dynamic mixer in a longitudinally flowed through housing / preferably in laminar flow conditions, preferably also for mixing liquids, emulsions or dispersions with high Viskositätsunter- 'or in extremely unequal proportions, V · 9. Use of the stirring device according to one of the items 1 to 7, characterized in that it is used to equalize the temperature and improve the heat exchange.  "'; ..- - 18 - 10 * Use of the stirring device according to one of the items 1 to 7, characterized in that it is used as a conveying member, Use of the stirring device according to one of the items 1 to 7 _f, characterized in that it is attached to an extruder, " ' . ' 1 , .· : wherein the rotor is connected to the head of the extruder shaft, is used, 12, use of the stirring device according to any one of the items 1 to 7, characterized in that it is used for mixing color approaches in polyacrylic solutions. For this 4 pages drawings