Turbine mixer

The invention relates to a Ringtrogmischer with a ring extending around a main axis mixing channel and with a mixer.

A specific form of mixing is dispersive mixing. Dispersion processes are required if undesired particle bonds in the form of agglomerations occur or occur in the mixing process. An example of such a task is the production of high-strength and ultra-high-strength concretes. For this purpose, so-called swirlers are used in ring trough mixers, which are typically occupied by rod-shaped elements. These penetrate the mixed material distributed in the mixer from top to near the mixing trough bottom. A major challenge, which also determines the cost-effectiveness of such processes, is to achieve the shortest possible mixing times. For this it is necessary to improve the efficiency of the mixing process.

The object of the invention is to provide a ring trough mixer with which such an increase in efficiency can be achieved.

In experiments, the inventors have determined the following relationships with regard to the task mentioned at the outset:<ul id="ul0001" list-style="dash" compact="compact"><li>In contrast to a large number of mixing-technical investigations, it was not possible to establish any correlation between the influence of the mixing result due to changes in the peripheral speed or the Froude number (mixed material acceleration) customary in fluid mechanics.</li><li>It is not the mixing time or the mixing intensity that is decisive for the minimization of the agglomerations and thus the desired product quality, but the frequency with which the mix is ​​stressed by the swirlers in the time considered.</li><li>The frequency of use is determined by the swirler speed, the swirler number of turbines per swirler and the number of swirler.</li><li>The required frequency of use drops or approaches an optimum when the ratio of the mean value of the swirler diameter to the annular channel width approaches 1. This means that both swirler have a pitch circle diameter equal to the ring trough width.</li><li>With the reduction of the frequency of use, the necessary energy input to achieve the desired mixing quality, the temperature entry and the wear are minimized at the same time.</li><li>The effectiveness of the swirl bars is also determined by their depth of penetration into the mix. This means that the distance of the turbolift rod end to the trough bottom should be kept as low as possible, depending on the coarse grain used.</li><li>The same connections apply to a swirly.</li></ul>

Against this background, the invention relates to a ring trough mixer with a mixing channel extending annularly around a main axis and with a mixer having at least one swirler mounted rotatably about the main axis, on which at least one swirler is arranged, which rotates in the mixing channel upon rotation of the swirler and on Wirblerträger can be rotated about its own, parallel to the main axis vortex axis, wherein the ratio of the mean value of the swirler diameter D_w to the width B_r the mixing channel meets the following requirements: <maths id="math0001" num=""><math display="block"><mrow><mfrac><mrow><mfrac><mn>1</mn><mi>n</mi></mfrac><mrow><mstyle displaystyle="false"><mrow><munderover><mo>∑</mo><mrow><mi>x</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover></mrow></mstyle><mrow><mi mathvariant="italic">dw</mi><mo>,</mo><mi>x</mi></mrow></mrow></mrow><mi mathvariant="italic">br</mi></mfrac><mo>&gt;</mo><mn>0</mn><mo>,</mo><mn>6</mn><mspace width="1em" /><mi>if n</mi><mo>≥</mo><mn>2</mn><mo>;</mo></mrow></math><img file="EP3556525A1_D0001.tif" /></maths> and <maths id="math0002" num=""><math display="block"><mrow><mfrac><mrow><mrow><mstyle displaystyle="false"><mrow><munderover><mo>∑</mo><mrow><mi>x</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover></mrow></mstyle><mrow><mfrac><mrow><mi mathvariant="italic">dw</mi><mo>,</mo><mi>x</mi></mrow><mi>x</mi></mfrac></mrow></mrow></mrow><mi mathvariant="italic">br</mi></mfrac><mo>&gt;</mo><mn>0</mn><mo>,</mo><mn>7</mn><mspace width="1em" /><mi>if n</mi><mo>=</mo><mn>1</mn><mo>;</mo></mrow></math><img file="EP3556525A1_D0002.tif" /></maths> where B_r the width of the mixing channel, D_{w, x} is the diameter of the x-th vortex and n is the number of swirlers.

In one embodiment it is provided that <maths id="math0003" num=""><math display="block"><mrow><mfrac><mrow><mfrac><mn>1</mn><mi>n</mi></mfrac><mrow><mstyle displaystyle="false"><mrow><munderover><mo>∑</mo><mrow><mi>x</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover></mrow></mstyle><mrow><mi mathvariant="italic">dw</mi><mo>,</mo><mi>x</mi></mrow></mrow></mrow><mi mathvariant="italic">br</mi></mfrac><mo>&gt;</mo><mn>0</mn><mo>,</mo><mn>75</mn><mspace width="1em" /><mi>if n</mi><mo>≥</mo><mn>2</mn><mo>;</mo></mrow></math><img file="EP3556525A1_D0003.tif" /></maths> and <maths id="math0004" num=""><math display="block"><mrow><mfrac><mrow><mrow><mstyle displaystyle="false"><mrow><munderover><mo>∑</mo><mrow><mi>x</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover></mrow></mstyle><mrow><mfrac><mrow><mi mathvariant="italic">dw</mi><mo>,</mo><mi>x</mi></mrow><mi>x</mi></mfrac></mrow></mrow></mrow><mi mathvariant="italic">br</mi></mfrac><mo>&gt;</mo><mn>0</mn><mo>,</mo><mn>85</mn><mspace width="1em" /><mi>if n</mi><mo>=</mo><mn>1.</mn></mrow></math><img file="EP3556525A1_D0004.tif" /></maths>

In one embodiment, it is provided that the mixer has two or more swirler carriers rotatably mounted about the main axis, on each of which at least one swirler is arranged, and / or that exactly one swirler is arranged on each swirler carrier. In this embodiment, the numeral n ≥ 2, so that:<maths id="math0005" num=""><math display="block"><mrow><mfrac><mrow><mfrac><mn>1</mn><mi>n</mi></mfrac><mrow><mstyle displaystyle="false"><mrow><munderover><mo>∑</mo><mrow><mi>x</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover></mrow></mstyle><mrow><mi mathvariant="italic">dw</mi><mo>,</mo><mi>x</mi></mrow></mrow></mrow><mi mathvariant="italic">br</mi></mfrac><mo>&gt;</mo><mn>0</mn><mo>,</mo><mn>6</mn><mo>,</mo><mspace width="1em" /><mi>preferably n</mi><mo>&gt;</mo><mn>0</mn><mo>,</mo><mn>75.</mn></mrow></math><img file="EP3556525A1_D0005.tif" /></maths>

An embodiment with exactly two swirler carriers, corresponding to n = 2, may be particularly preferred. Preferably, the two or more turbulence carriers are arranged at the same angular distance from one another. In the case of two swirler-carriers this would lead to an angular distance of 180 °, in the case of three swirler-carriers to an angular distance of 120 °, and so on.

In one embodiment, it is provided that corresponding turbulizers of different turbulence carriers and preferably all turbulizers are arranged at the same distance from the main axis. In the case of several swirlers per swarm bearer, corresponding swirlers of different swarm bearers are to be understood, for example, as the innermost swirlybirds of all swarming bearers. In this embodiment, in the operation of the ring trough mixer corresponding or all swirler in the same orbits in the mixing channel.

In one embodiment, it is provided that corresponding turbulizers of different turbulence carriers and preferably all turbulizers have the same vortex diameter D._w exhibit. As swirler diameter D_w is to be understood the diameter of that circle, which is drawn by the movement of the outermost vortex element, for example a vortex bar, during self-rotation of the vortex around the vortex axis.

In one embodiment, it is provided that the swirler or swirlers have one or more swirl rods, which are preferably arranged parallel to the swirling axis. For example, three, four or five vertebrae can be provided per swirler.

In one embodiment, it is provided that corresponding turbulizers of different turbulence carriers and preferably all turbulizers have the same number of vertebrae.

In one embodiment, it is provided that the proportion of the annular channel width detected by the swirlers is more than 0.75 and preferably more than 0.85. The proportion of the ring channel width detected by the turbulizers is calculated using the formula 1 - [(G_a+ G_i) / B_r], wherein the outer gap width G_a designates the distance between the annular channel outer wall and the outer side of the swirler closest to the annular channel outer wall and the inner gap width G_i the distance between the annular channel inner wall and the inside of the closest to the annular channel inner wall swirler.

The invention further relates to the use of a ring trough mixer according to the invention for dispersive mixing, in particular for mixing concrete. Ring trough mixers with the geometries according to the invention are particularly advantageous for dispersive mixing, for example for mixing high-strength or ultrafine concretes. But also in other applications, there are favorable results.

Further details and advantages of the invention will become apparent from the embodiment discussed below with reference to the figures. In the figures show:<dl id="dl0001"><dt>FIG. 1:</dt><dd>a sectional perspective view of a ring trough mixer of the prior art;</dd><dt>FIG. 2:</dt><dd>a side view of the prior art ring trough mixer of <figref idref="f0001">FIG. 1</figref>;</dd><dt>FIG. 3:</dt><dd>a plan view of the prior art ring trough mixer of <figref idref="f0001">FIG. 1</figref>;</dd><dt>FIG. 4:</dt><dd>a side view of a Ringtrogmischers according to the invention; and</dd><dt>FIG. 5:</dt><dd>a top view of the ring trough mixer according to the invention of Figure 4.</dd></dl>

As shown in the figures, ring trough mixers 1 generally comprise a cylindrical trough 2 having a trough inner radius R._a, in the middle of which a cylindrical housing 3 with a housing outer radius R_i is arranged, which receives the drive of the mixer. The width B_r arranged between trough 2 and housing 3, annular mixing channel 4 results from the difference R_a- R_i.

The mixer comprises a set of swirler carriers 5 (two in the examples shown) and is designed such that the swirler carriers 5 operate at a circulating speed U during operation of the swivel mixer_u around the main axis A running in the middle of the trough 2_H can circle. At each of the swirler carrier 5 a swirler 6 is arranged such that it is in the operation of the ring trough mixer with a swirler speed U_w around its parallel to the main axis A_H running, own whirling axis A_w can be rotated. During operation of the mixer, the swirlers 6 thus revolve as rotating planets the annular mixing channel 4. The swirler 6 each have a certain number of swirler rods 7 (four or five in the examples shown) and have a specific swirler diameter D._w, The smaller the distance of the turbulizer bars 7 from the bottom of the trough 2, the greater the penetration depth of the turbulence bars into the mix during operation.

In order to make the swirler 6 rotate about its own swirler axis aw1 or, respectively, the swirler carriers 5 and swirler 6 are either synchronized via a transmission or can be driven separately from one another. As a rule, the swirlers 6 are operated at higher rotational speeds than the swirler carriers 5, as U_w &gt; U_u, The direction of rotation of the swirler 6 can be varied with separate drive. Also, the direction of rotation of the swirler 6 when using two or more swirly 6 also differ.

In prior known ring trough mixers of the prior art, as in <figref idref="f0001 f0002 f0003">Figures 1-3</figref> shown, in the case of at least two turbulence carriers 5 and 6 swirler the swirler 6 at different distances S_{w, 1} or S_{w, 2} arranged from the center of the trough 2, so that they revolve in different orbits in the mixing channel 4 during operation of the ring trough mixer. The distances S_{w, 1} or S_{w, 2} correspond to the distances of the vortex axes A_{w, 1} or A_{w, 2} to the main axis A_H, The number of swirler rods 7 per swirler 6 is typically limited to five. In practice also differences in the swirler diameters D are_w1 and D_w2 In any case, the ratio of the mean value of the swirler diameter (D_{w, 1}D +_{w, 2}) / 2 to the mixing channel width B_r less than 0.6 and in known ring trough mixers with only one swirler 6, the ratio of the swirler diameter D._w to the mixing channel width B_r less than 0.7. The distance between the trough wall and the outside of the closest to the trough wall swirler is present as the outer gap width G._a denotes and the distance between the housing wall and the inside of heranreichenden closest to the housing wall swirler as the inner gap width G._i, From these two, not shown in the figures sizes and the mixing channel width B_r can be calculated from the formula 1 - [(G_a+ G_i) / B_r] the proportion of the detected by the Whirler 6 ring channel width can be calculated. This proportion is typically less than 75% in prior art trough mixers.

The in <figref idref="f0004 f0005">Figures 4-5</figref> shown, comprising a pair of swirler 6, each with a swirler 6, wherein the two swirler 6 are arranged at the same distance from the center of the trough 2, so that they rotate in operation in the same orbits in the mixing channel 4 (ie_w1= Sw₂). Both swirler 6 have the same swirler diameter (ie D_w1= D_w2) and the same number of swirler bars 7 (four in the example shown). The provided according to the invention minimum for the ratio of the mean value of the swirler diameter, here the applicable for both swirler swirler diameter to the mixing channel width of 0.6 (in the case of only one swirler 6, it would be 0.7) is achieved in the embodiment shown anyway as well as a Proportion of over 75% for the ring channel width detected by the swirlers 6.