|Title of Invention||
|Abstract||A stirring device (1) for a mash-and/or wort vessel (2) with improved mixing or stirring effect is described. For this purpose, a stirring surface (12) is provided which is at least in sections provided with irregularities (14) containing a plurality of projections (14a) and depressions (14b) spaced apart.|
|Full Text||Stirring device
The invention is related to a stirring device for food which is in particular appropriate to be employed in mash and/or wort vessels for beer production.
The stirring device in vessels for the food industry, in particular in mash pans or mash coppers, is very important. For example, for mashing the dimensioning of the stirring device has to be carefully adjusted to the special conditions in operation, so that the relative peripheral speed of the stirring device does not exceed a predetermined amount (maximally 3 m/s) as otherwise shearing forces occur at the mash parts which can alter the ingredients of the mash. On the other hand, the stirring effect is naturally reduced and/or the stirring time is increased if the peripheral speed is reduced to below an acceptable degree. Furthermore, the heat flow is reduced and fouling at the fire surfaces is increased.
The object underlying the invention is to provide a stirring device having an improved stirring effect.
The object is achieved by the features stated in claim 1.
By the embodiment according to the invention, a stirring surface is provided which generates turbulences even at relatively low, limited speeds due to its irregularities in the form of projections and depressions, and thus also improves the stirring effect. Moreover, with stirring tasks simultaneously effecting a conversion of substances, as is for example the case in mash pans or coppers, the conversion of substances is essentially improved.
Advantageous further developments of the invention can be taken from the subclaims.
If the irregularities are essentially uniformly distributed across the stirring surface, the stirring effect can be better predicted and reproduced. This is in particular true if all projections and/or all depressions are essentially identical.
A continuous course of the projections and/or depressions and a continuous transition between adjacent projections and depressions further improves the stirring effect, the
projections preferably being curved like a cushion.
The stirring surface is preferably provided on a double-walled component that was made of a first and a second plate or sheet metal, respectively. The plates were connected via spaced junctions and subsequently at least one plate was curved by applying pressure between the plates at the unconnected sites. In this manner, the embodiment, the size and the mutual distances of the projections and/or depressions can be precisely controlled.
The stirring device according to the invention preferably includes a first and a second stirring surface separated from one another by a gap through which substance for stirring can pass. At least one of the stirring surfaces is here provided with irregularities.
The advantages of the stirring surface designed according to the invention particularly show to advantage if the stirring surface is arranged on a stirrer blade curved as a shovel and connected with a rotary axle or axis via an arm.
By the means for feeding in fluids integrated in the stirring device, it is possible, with a simple construction and an extremely economical process, to introduce additional substances into the stirring vessel and to simultaneously finely distribute them. The rotating stirring device uniformly distributes the added fluids already from the beginning in the substance for stirring without any further employment of energy, the distribution being subsequently even improved by repeated stirring. This embodiment of the stirring device for feeding in fluids can be particularly preferably realized in a stirring device the stirring surfaces of which comprise irregularities; other known stirring devices, however, can also be provided with a means for feeding in fluids according to the invention.
In the following, embodiments of the invention are illustrated more in detail with reference to the drawings. In the drawings:
Fig. 1 shows a schematic representation of a stirring vessel with a stirring device designed according to the invention,
Fig. 2 shows the section II-II of Fig. 1,
Fig. 3 shows an enlarged perspective view of a stirrer blade,
Fig. 4 shows a perspective view of a stirrer blade from the bottom,
Fig. 5 shows a schematic, perspective representation of a stirring surface of the stirring device according to the invention,
Fig. 6 shows the section IV-IV of Fig. 2,
Fig. 7 shows the plan view onto a first pattern of the irregularities,
Fig. 8 shows the plan view onto a second pattern of the irregularities, and
Fig. 9 shows the plan view onto a third pattern of the irregularities.
In Fig. 1, in a schematic, perspective representation, an embodiment of a stirring device 1 according to the invention is shown that is arranged in a stirring vessel 2. In the represented embodiment, the stirring device 1 according to the invention is designed as stirring device for a vessel for a substance for stirring containing solid and liquid ingredients, in particular for beer production, i.e. for a mash- and/or wort vessel, in particular a mash pan or a mash copper. However, the invention can also be employed for solid/liquid mixtures or viscous media in food industry in general.
The stirring vessel 2 of the represented embodiment contains an essentially cylindrical side wall 2a and a conical bottom 2b having its deepest point in the area of the central axis 2' of the stirring vessel 2.
In the represented embodiment, the stirring device 1 contains stirring tools la, i.e. two stirrer blades 3 having an essentially identical design and being connected via one arm 4 and a common hub 5 each with a rotary drive such that they can be rotated about the central axis 2' in the direction of the arrow A.
In the radial direction with respect to the stirring vessel 2, the stirrer blades 3 are shorter than the diameter D of the stirring vessel 2. The two arms 4 with their stirrer blades 3 are arranged opposite one to another at the central line 2' and extend over a length of preferably 0.5D to 0.95D, preferably 0.8D.
Both stirrer blades 3 are essentially identical, so that one stirrer blade 3 is described below. As can be also seen in connection with Figs. 2 to 4, the stirrer blade 3 has an essentially trapezoidal design. Its smallest dimensions are located in the sense of rotation A near the mounting at the arm 4, and its largest dimension is located in the sense of rotation A at its free end facing the wall 2a.
The stirrer blade 3 contains two essentially plate-like stirring elements 6, 7 which are connected to one another as well as to the arm 4 at a distance a in a stacked manner by means of holding cheeks 8. Each of the stirring elements 6, 7 contains at its lower end, i.e. the end closest to the bottom, edges 9 and 10, respectively, that are forward in the sense of rotation A and essentially extend radially to the central line 2' and essentially in parallel to the bottom 2b. The forward edge 9 of the upper stirring element 6 is set back behind the forward edge 10 of the lower stirring element 7 in the sense of rotation A. The lower stirring element 7 contains two areas 7a, 7b, the area 7a being provided with the forward edge 10 and extending approximately in parallel to slightly ascendingly (up to 10°) with respect to the bottom 2b, and the area 7b extending in a steeper ascent towards the rear, i.e. opposite the sense of rotation A.
The free edge 9 of the upper stirring element 6 is essentially at a distance a above the transition between the area 7a and the area 7b of the lower stirring element 7.
The upper stirring element 6 is longer than the lower stirring element 7 in the sense of rotation A and has an essentially shovel-like curve. The area 6a following the free edge 9 of the stirring element 6 extends over at least the length of the area 7b, and preferably over the complete length of the area 7b of the lower stirring element 7 essentially in parallel to the area 7b. Preferably, however, the greatest distance a is between the free edge 9 and the area 7b, and the areas 6a and 7b converge towards the rear at an angle of approx. 4°. Between the upper stirring element 6 and the lower stirring element 7, a gap 11 thus extends and connects
the front side of the stirrer blade 3 in the sense of rotation A with the rear side and is dimensioned such that the substance for stirring can pass through. Adjacent, the upper stirring element 6 is curved to the top and rear, which can be either realized by a corresponding curve or, as in the represented embodiment, by stringing together a plurality of segments at an angle one to another.
The surface 12 (upper stirring element 6) or 13 (lower stirring element 7) working against the stirred material when the stirrer blades 3 are rotated in the sense of rotation A will be each referred to as stirring surface below. At least the stirring surface 12 at the stirring element 6, i.e. at the upper, longer stirring element, is provided with a plurality of irregularities designated with 14 altogether, while the stirring surface 13 of the lower stirring element 7 is preferably even. However, it is also possible to provide both stirring surfaces 12 and 13 as well as possibly also one or both back sides of the stirring elements 6 and 7 with the irregularities. The irregularities 14 are designed such that they take care of the generation of micro-turbulences when the substance for stirring flows against them and thus improve the thorough mixing of the substance for stirring. To this end, the irregularities interrupt an even plane surface, preferably to such a degree that the stirring surface 12 does not comprise any flat plane areas and the irregularities 14 thus preferably completely cover the stirring surface 12. The irregularities 14 contain projections 14a and depressions 14b, respectively, the terms "projections" and "depressions", however, meaning, independently of their manufacture, a more or less long distance to an imaginary reference plane, as is in particular represented more in detail in Figs. 3 and 4. A plurality of projections and depressions are provided, the number being adjusted to the size of the stirring surface 12 and/or the desired stirring result with a special substance for stirring. The number is greater than 2 and can be up to 10 or up to 50 or up to 100 or more. In Figs. 3 and 4, the projections 14a are curved like a cushion and continuously pass into the depressions 14b. In the pattern of irregularities 14 represented in Fig. 3, the depressions 14b have an essentially point-like design and are uniformly arranged in horizontal and vertical parallel rows, the rows as well as the depressions 14b within the rows being spaced apart. The distances are preferably the same, so that a uniform pattern of projections 14a results. In Fig. 3, the course of the apex lines or the lines with curve reversal are represented. The irregularities 14 according to the pattern according to Fig. 3 are preferably arranged on the stirring surface 12 such that the free edge 9 extends through the summits of adjacent projections 14a as is represented in Fig. 4.
The irregularities 14 are preferably produced by stacking two sheet metals or plates 15a, 15b with preferably different strengths and connecting them at the points of the future depressions. In the represented embodiment, the difference in strength is achieved by a lower thickness d2 of plate 15a with respect to a greater thickness dl of plate 15b. In the embodiment of Figs. 3 and 4, these junctions 16 essentially have the shape of a point, lens or ring. Furthermore, the two plates 15 a, 15b are also pressure-tightly connected to one another in their edge areas. If then a pressure means is introduced between the two plates 15a, 15b, the plate with the lower strength, which is plate 15a of the same material and of a lower strength d2, is curved outwards between the junctions 16 in plastic deformation, cavities 17 defining the projections 14a that are formed in the process. The pressure is selected such that the second plate 15b with the greater thickness dl essentially remains plane and thus forms the plane back side of the stirring element 6. However, it is also possible to select the plates 15a, 15b and/or the applied pressure such that both plates 15a, 15b are curved either to the same extent or to a different extent.
Both plates 15a, 15b are made of a material that is on the one hand chemically resistant with respect to the substance for stirring and also has a strength sufficient for stirring, and is food safe for being employed for stirring food. A preferred material for both plates 15a, 15b is stainless high-grade steel, in particular nickel chromium steel. The junctions 16 are preferably made by welding.
Provided that the strength is sufficient, the stirring element 6 can be formed by the two plates 15a, 15b (Fig. 4) alone. The thickness dl of the plate 15b can be between 0.5 to 10.5, while the smaller wall thickness d2 of the plate 15a can be between 0.5 and 10 mm.
The pattern of irregularities 14 can be changed with respect to size and arrangement as well as the regularity of the distribution of the projections 14a and the depressions 14b, respectively. The shape of the junctions 16 can also be changed. Thus, the junctions 16 can comprise pointer ring-shaped junctions 16a and linear junctions 16b, as is represented in Figs. 5 to 7. Thus, the pattern of the irregularities 14, as is shown in Fig. 5, can comprise rows of junctions 16 where diagonal linear junctions 16 alternate with point- or ring-shaped junctions 16a and the rows are regularly or irregularly offset with respect to one another.
The irregularities 14 can also be purposefully arranged such that a certain flow direction S is supported, as is, for example, shown in Fig. 6. Here, the linear junctions 16b are arranged in spiral rows at a distance one after the other in a flow direction S into which the material is to be moved.
Fig. 7 shows a pattern of irregularities 14 leading to a very uniform distribution of the projections 14a without preferring a certain flow direction. Here, point and ring-shaped junctions 16a are radially surrounded by four linear junctions 16b each.
It is obvious that by the different distribution and different shapes of the junctions 16, very different patterns, including very irregular patterns of irregularities 14 can be generated. For example, the projections can have the shape of waves or bubbles. It is furthermore possible to form the projections 14a and/or the depressions 14b at different points of the stirring surface 12 with different sizes or different shapes. By an appropriate orientation of the depressions and/or the projections to the free edge 9, the stirring effect can also be changed as desired.
Surfaces provided with irregularities for the manufacture of a bottom and/or a wall of the stirring vessel have already been described in the not priorily published EP 05 002 298.7, the disclosure of which is incorporated herein by reference. There, the cavities 17 formed for generating the projections 14a are simultaneously used for vapor distribution inside the walls.
For the stirring surface of the present invention, all surfaces provided with irregularities described therein can be employed.
The present invention is in particular suited for the manufacture of a stirring device for a stirring vessel, the inner sides of which are also provided with irregularities, in particular a stirring vessel as it has been described in the not priorily published EP 05 002 298.7, where, however, the cavities 17 of the stirring surface are preferably not used for heating. With this combination, particularly effective stirring and thorough mixing is achieved, and even improved conversion of substances is achieved with substance for stirring, in particular mash, where this is desired. In this case, the stirring surface can be provided with the same
irregularities as the bottom and/or wall of the stirring vessel 2, or with irregularities having a different arrangement and/or shape.
As can be taken from Figs. 1 to 4, the stirring device 1 is provided with a means 20 for feeding in fluids. With the means 20, fluid additions can be introduced into the substance for stirring during stirring. Thus, for example, water of a predetermined temperature can be introduced for heating or cooling the substance for stirring. It is furthermore possible to introduce via the means 20 according to the invention other additives or additional substances that have to be finely distributed in the substance for stirring. For example, enzymes or lactic acid, technical or natural, for example used for reducing the pH value, or other substances can be introduced and finely distributed, in particular in beer production. If hot water is added, in beer production this could be for example hot water recycled from exhaust vapors.
The feeding means 20 contains at least one distributor 21 rotating about the rotary axle or axis 2' connecting a feeding means 22 with at least one outlet 23. The outlet 23 rotates about the rotary axle or axis 2'. Preferably, the outlet 23 is connected with the arm 4 and is taken along with the rotation of the arm 4. In the represented embodiment, the outlet is provided directly in the distributor 21. The outlet 23 faces downwards. The feeding means 22 contains a distribution chamber formed inside the hub 5 and supplied from outside the stirring vessel 2 with the fluid to be distributed via a supply line 24.
In the represented embodiment, preferably both stirring tools la are provided each with a distributor 21. Below only the means 20 of one of the stirring tools la is described, and the other stirring tool has an identical design. The distributor 21 is preferably fixed to the bottom side of the arm 4 and preferably extends to the area underneath the stirrer blade 3. The distributor 21 comprises a connection with the supply line 24 which preferably extends through the distribution chamber 22 of the hub 5.
A plurality of outlets 23 is provided preferably only in the area of the stirrer blades 3. The outlets 23 preferably have a nozzle-like design. The constructionally simplest solution are simple openings in the distributor 21 having the size of nozzles. The outlets 23 are preferably directed perpendicularly downwards towards the bottom 2b, however, they can also face to
any other direction, or outlets can be provided which face to different directions at the same stirring tool la.
In a practical test, enzymes were fed to the mash by metered addition in the stirring device 1 according to the invention with the stirrer blades provided with irregularities and the means 20 for feeding fluid. It was found that the enzymes could be distributed in the substance for stirring within only a few seconds. Normally, an optimal thorough mixing takes up to 15 min.
As a modification of the described and drawn embodiments, the projections and/or depressions of the stirring surface can also be generated otherwise. They can, for example, be formed at the surface or be manufactured by cutting or non-cutting shaping or the like. The shape and the constructive embodiment of the stirring device can be adapted to the special stirring task. It is furthermore possible to also provide the lower stirring surface with irregularities. Finally, the invention can also be employed for stirring vessels with a different design. The feeding means for fluids can be furthermore arranged only at one stirring tool. Outlets can be provided across the whole radial extension of the stirring tools or be concentrated at certain points, also outside the stirrer blades. Instead of nozzle-like openings appropriate for injection, larger openings from which the fluid runs out can also be provided. It is true that for the intended function it is possible to only employ one outlet, but preferably several outlets are provided.
1. Stirring device (1) with a stirring surface (12) provided at least in sections with irregularities (14), characterized in that in particular for a mash-and/or wort vessel (2), the irregularities (14) contain a plurality of projections (14a) and/or depressions (14b) spaced from each other and curved like cushions.
2. The stirring device as claimed in claim 1, wherein the irregularities (14) are essentially uniformly distributed across the stirring surface (12).
3. The stirring device as claimed in claim 1 or 2, wherein all projections (14a) and/or all depressions (14b) are essentially identical.
4. The stirring device as claimed in one of claims 1 to 3, wherein the stirring surface (12) is completely covered with projections (14a) and depressions (14b).
5. The stirring device as claimed in one of claims 1 to 4, wherein the projections (14a) and depressions (14b) continuously pass to one another.
6. The stirring device as claimed in one of claims 1 to 5, wherein the projections (14a) are curved as cushions.
7. The stirring device as claimed in one of claims 1 to 6, wherein the stirring surface (12) is made of a first and a second plate (15a, 15b),
the plates (15a, 15b) being connected to one another via spaced junctions (16), and at least one of the plates (15a) being curved between the junctions (16) for forming the irregularities (14).
8. The stirring device as claimed in one of claims 1 to 7, wherein a first and a second stirring surface (12, 13) are provided, which are separated by a gap (11) through which substance for stirring can pass, wherein at least one of the stirring surfaces (12) is provided with the irregularities (14).
9. The stirring device as claimed in one of claims 1 to 8, wherein the stirring surface (12) is arranged on a stirrer blade (3) curved like a shovel which is connected with a rotary axle or axis (2) via an arm (4).
10. The stirring device as claimed in one of claims 1 to 9, wherein its use in a stirring vessel (2) with an inner bottom surface provided with irregularities (14) and/or with an inner wall surface provided with irregularities (14).
11. The stirring device, in particular as claimed in one of claims 1 to 10 having an integrated means (20) for feeding fluids.
|Indian Patent Application Number||2716/DELNP/2007|
|PG Journal Number||12/2013|
|Date of Filing||12-Apr-2007|
|Name of Patentee||KRONES AG|
|Applicant Address||BOEHMERWALDSTRASSE 5, 93073 NEUTRAUBLING (DE)|
|PCT International Classification Number||B01F 7/18|
|PCT International Application Number||PCT/EP2006/002571|
|PCT International Filing date||2006-03-21|