Blade for impeller of stirrer, impeller and stirrer
By designing a blade structure with a width greater than 55% of the height and a twisted blade body, combined with sleeve protection, the problems of high power consumption and inflexible operation of existing agitators have been solved, achieving efficient and reliable mixing effect and flexible adaptability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2017-02-28
- Publication Date
- 2026-04-03
AI Technical Summary
Existing agitators suffer from high power consumption, inflexible operation, and difficulty in adapting to different applications or process conditions when mixing or stirring fluids.
Design a new blade structure with a blade width of at least 55% of its height, a large difference in principal curvature between the leading and trailing edges, and the blade twisting around the main axis. The blade can be adjusted and installed, and combined with a sleeve to protect the drive shaft, to achieve efficient mixing and flexible adaptation.
It achieves low power consumption, high-efficiency mixing or stirring, and can adapt to different applications and process fluid variations, providing reliable operating results.
Smart Images
Figure CN121775697A_ABST
Abstract
Description
[0001] This invention is a divisional application, with its parent application number being 201710111976.X, the application date being February 28, 2017, and the invention title being "Blades for an Impeller of a Stirrer, Impeller and Stirrer". Technical Field
[0002] This invention relates to blades for an impeller of a stirrer, as described in the preamble of an independent claim, the stirrer being used to mix or agitate process fluids. The invention also relates to an impeller of a stirrer comprising such blades, and to a stirrer having such an impeller. Background Technology
[0003] Agitators are used in many different industrial processes for mixing or stirring process fluids. In most applications, the process fluid is contained in a tank, tower, or other container, and the agitator is mounted to the wall, bottom, or lid of said container. Agitators are used in a wide range of industries, such as the pulp or paper industry. Here, agitators are used, for example, in dilution, mixing, or bleaching processes.
[0004] Basically, an agitator includes: an impeller or propeller for agitating fluids; and a shaft connected at one end to the impeller and at the other end to a drive unit for rotating the shaft and impeller together. The drive unit typically has a motor and a coupling for connecting the motor to the shaft, wherein the coupling includes a belt drive, a gearbox, or any other suitable transmission device.
[0005] Typically, the drive unit is located outside the vessel, while the shaft with the impeller is located inside the vessel for agitating the process fluid. Top-mounted and side-mounted agitators are known. Top-mounted agitators are typically mounted to the lid or top of a tower or vessel and have a vertically extending shaft. Side-mounted agitators are typically mounted to the side wall of a tower or vessel and have a horizontally extending shaft. Examples of both types of agitators are those sold by the applicant under the brands SALOMIX™ and SCABA™.
[0006] In modern industrial processes, there is a demand for highly efficient mixing and agitation solutions. In particular, there is a desire for minimal power consumption, reliable operation, and optimal process results. Furthermore, agitators are often required to be highly flexible in their application; that is, they should be adaptable to different processes or process conditions, such as adapting to different or changing compositions of the process fluid. Summary of the Invention
[0007] This invention addresses this need.
[0008] Therefore, the object of the present invention is to provide a novel blade for an impeller of a stirrer used for mixing or agitating process fluids, thereby providing high agitation efficiency, reliable operation, and flexibility in adapting to different applications. Furthermore, the object of the present invention is to provide a corresponding impeller for a stirrer, and a novel stirrer having such an impeller.
[0009] The subject matter of the invention that achieves this objective is described by the features of the independent claims.
[0010] Therefore, according to the present invention, a blade for an impeller of a stirrer for mixing or agitating process fluids is provided, comprising: a seat for mounting the blade to the impeller; and a blade body for mixing or agitating process fluids, the blade body being connected to the seat, the blade body having a leading edge, a trailing edge, and a blade tip extending from the leading edge to the trailing edge at an end of the blade body opposite to the seat, and the blade body having a height and a width, wherein the height is the maximum distance of the blade tip from the seat, and wherein the width is the distance of the leading edge from the trailing edge, and wherein the blade body has a maximum width of at least 55% of the height, preferably at least 65%.
[0011] The new design of the blade, and especially its considerable width relative to its height, results in very high efficiency of the mixing or stirring action, combined with reliable and excellent results.
[0012] Furthermore, since the blade includes a seat for mounting the blade to the impeller, the blade according to the invention is highly flexible in adapting the blade to different or varying conditions of the process fluid. Because the blade is designed to be detachable from the impeller, the blade can be easily replaced or fixed in a different orientation relative to the impeller hub.
[0013] In particular, considering the high efficiency for many applications, such embodiments are preferably wherein the maximum width is at least 70% of the height, and more preferably at least 75% of the height.
[0014] The width of the leaf blade typically changes from the base in the direction toward the leaf tip. For high efficiency, another preferred measure is that the maximum width of the leaf blade lies in the region between 40% and 70% of the leaf blade height, preferably between 50% and 60% of that height. Thus, starting from the base and moving in the direction toward the leaf tip, the width of the leaf blade initially increases until it reaches its maximum width in said region. With further movement toward the leaf tip, the width of the leaf blade preferably decreases.
[0015] For the sake of high efficiency, another advantageous measure is that the leading edge extends from the base to the blade tip with a principal curvature greater than that of the trailing edge. The term "principal curvature" is used to indicate that the curvature of both the leading and trailing edges is not constant, but changes along the respective edges. However, especially in the region of the blade where it has its maximum width, the curvature of the leading and trailing edges can be approximated by corresponding constant curvatures, for example, by corresponding circles. The radius of said circle is then considered the principal curvature of the respective edge.
[0016] According to an embodiment of the blade as described in the present invention, the principal curvature of the trailing edge has a radius that is at least 1.5 times, preferably at least 1.8 times, the radius of the principal curvature of the leading edge.
[0017] According to a preferred embodiment of the blade, the blade body is connected to the seat in a base plane and has a main axis extending perpendicularly to the base plane in a direction to the tip of the blade body, wherein the blade body is twisted about the main axis.
[0018] Preferably, the twist of the blade is achieved such that the average direction of the ridge line of the profile of the blade parallel to the base plane rotates about the main axis as the distance from the base plane increases.
[0019] In a preferred embodiment of the blade, the average direction of the ridge line of the profile near the base plane and the average direction of the ridge line of the profile near the tip of the blade extend relative to each other at a torsion angle of at least 30°.
[0020] The twisting of the blade around the main axis is beneficial for the high mixing or stirring efficiency of the blade.
[0021] Considering the high flexibility to adapt to different applications or varying characteristics of process fluids, it is preferable that the seat is designed as a flange seat for mounting the blade flange to the hub.
[0022] Furthermore, according to the present invention, an impeller for a mixer used for mixing or stirring process fluids is provided, comprising a hub and a plurality of blades mounted to the hub, wherein each blade is designed according to the present invention, and each blade is mounted to the hub by means of a corresponding seat. The impeller has high mixing or stirring efficiency and provides reliable and very good process results.
[0023] Preferably, each blade is adjustablely mounted to the hub. This allows the impeller to be easily adapted to different applications or different conditions of the process fluid.
[0024] According to a preferred embodiment, the impeller has three blades.
[0025] According to another aspect of the invention, an agitator for mixing or stirring process fluids is provided, comprising: an impeller for stirring or mixing the process fluids; a drive unit for rotating the impeller; and a drive shaft connecting the impeller to the drive unit, wherein the impeller is designed according to the invention. This agitator, combined with low energy consumption, ensures high efficiency, reliable operation, and excellent process results. Furthermore, the agitator can be easily adapted to many different applications.
[0026] According to a preferred embodiment, the agitator has a mounting flange for securing the agitator to the wall of a container used for the process fluid. The drive shaft includes an inner shaft and a sleeve coaxially surrounding the inner shaft and extending between the impeller hub and the mounting flange. The sleeve is designed such that it prevents contact between the inner shaft and the process fluid when the agitator is mounted to the container wall. By providing a protective sleeve to the drive shaft, a cost-effective inner shaft can be used, wherein the inner shaft is protected by the sleeve from corrosive process fluids or from corrosion and / or abrasion.
[0027] According to one embodiment, the agitator is designed to be mounted horizontally to the wall of a vessel for process fluids. However, the agitator can also be designed to be mounted to other types of vessels, towers, tanks, etc.
[0028] Further advantages and embodiments of the invention will become apparent from the dependent claims. Attached Figure Description
[0029] The invention will be described in more detail below with reference to the accompanying drawings. The invention is illustrated schematically, and in part in cross-sectional view, as follows: Figure 1 This is a perspective view of an embodiment of the stirrer according to the present invention; Figure 2 This is a perspective view of an embodiment of the blade according to the present invention; Figure 3 yes Figure 2 A top view of an embodiment of the blade shown; Figure 4 yes Figure 2 A plan view of an embodiment of the blade shown; Figure 5 yes Figure 2 A bottom view of an embodiment of the blade shown; Figure 6 Is with Figure 4 Similar planar diagrams illustrate the principal curvatures of the leading and trailing edges, respectively; Figure 7 yes Figure 2 The profile of the blade shown is in a cross section parallel to the base plane and close to the base of the blade. Figure 8 Is with Figure 7 Similar outline, but closer to half the height of the leaf blade; Figure 9 Is with Figure 7 Similar outline, but closer to the tip of the leaf blade; Figure 10 A perspective view of an embodiment of the impeller according to the present invention; and Figure 11 yes Figure 1 A cross-sectional view of an embodiment of the agitator shaft shown. Detailed Implementation
[0030] To better understand, firstly, refer to Figure 1 This section explains the general settings for a mixer. Figure 1 A perspective view of an embodiment of a stirrer according to the invention, generally identified by reference numeral 100, is shown. The stirrer includes an impeller 50 having a hub 51 and three blades 1, each of the three blades 1 having: a seat 2 for mounting the corresponding blade 1 to the hub 51; and a blade body 3 connected to the seat 2 for stirring or mixing process fluids. The impeller 50 and each blade 1 are respectively designed according to an embodiment of the impeller or blade according to the invention, which will be described in more detail below.
[0031] The hub 51 of the impeller 50 is connected to one end of the drive shaft 60. The other end of the drive shaft 60 is operatively connected to a drive unit 70 for rotating the drive shaft 60 and the impeller 50 connected thereto about axis A. The drive unit 70 includes a motor 71, such as an electric motor 71, and a connector 72 for operatively connecting the motor 71 to the drive shaft 60.
[0032] Figure 1 The connector 72 shown has a belt drive for connecting the motor 71 to the drive shaft 60. It is self-evident that the invention is not limited to such a belt drive. The drive unit 70 of the stirrer 100 according to the invention may also incorporate any other connector 72 known in the art between the motor 71 and the drive shaft 60, such as a gearbox or any other suitable transmission device. Furthermore, Figure 1 The relative arrangement of the motor 71, coupling 72, and drive shaft 60 shown should be understood as exemplary. Many other arrangements equally suitable for the agitator according to the invention are known in the art.
[0033] Figure 1The illustrated embodiment of the agitator 100 is designed as a side-mounted agitator and is designed for horizontal mounting to the wall of a container, tank, tower, box, or any other storage vessel; that is, the drive shaft 60 extends horizontally in the usual use orientation of the agitator 100. While this is a preferred embodiment for the agitator 100 according to the invention, the invention is not limited to side-mounted or horizontal agitators. Agitators according to the invention can also be designed, for example, as top-mounted or vertical agitators, wherein the drive shaft extends vertically in the usual use orientation.
[0034] Figure 1 The side-mounted agitator 100 shown has a mounting flange 80 for securing the agitator to the wall of a container, tank, tower, etc. The mounting flange 80 is coaxially surrounding a drive shaft 60 and includes a plurality of holes for receiving screws or bolts for securing the agitator 100 to the wall. When the agitator 100 is mounted to the wall, the portions of the mounting flange 80, impeller 50, and drive shaft 60 between the mounting flange 80 and the impeller 50 are located within the container, tank, tower, etc., containing a process fluid to be agitated or mixed by the impeller 50. Further details of the agitator 100, such as seals and bearings, are well known to those skilled in the art and are therefore not described in further detail.
[0035] Now turn to blade 1, and refer to Figures 2 to 5 An embodiment of the blade 1 according to the present invention will be described. Figure 2 An overall perspective view of an embodiment of the blade 1 according to the present invention is shown. Figure 3 This is a top view of this embodiment of blade 1. Figure 4 It is a plan view of the inhalation side of the blade, and Figure 5 This is the bottom view of blade 1.
[0036] The blade 1 includes: a seat 2 for mounting the blade 1 to the impeller; and a blade body 3 for mixing or agitating the process fluid. The blade body 3 is connected to the seat 2, for example, by welding or by any other suitable process. Of course, the blade body 3 and the seat 2 can also be made as a single piece, that is, the blade body 3 can be integrally formed with the seat 2 as a single piece.
[0037] The base 2 is a disc-shaped cylinder with a lower planar surface 22 and a upper planar surface 21, and the blade 3 is connected to the upper planar surface 21. The upper surface 21 of the blade 3 defines the base plane 4, that is, the base plane 4 is a plane including the upper surface 21. The center of the upper surface 21 is indicated by C.
[0038] The blade 3 extends in a direction perpendicular to the base plane 4 and has a leading edge 31, a trailing edge 32, and a blade tip 33 extending from the leading edge 31 to the trailing edge 32 at the end of the blade 3 away from the seat 2. The blade 3 has two surfaces extending from the leading edge 31 to the trailing edge 32, namely, a pressure side 34 and an intake side 35 (see...). Figure 4 ).
[0039] It should be understood that when blade 1 is installed to impeller 50 of agitator 100, the terms “leading edge”, “trailing edge”, “pressure side”, “suction side”, etc., refer to the operating state, respectively.
[0040] The blade 3 extends along the main axis M, which is an axis perpendicular to the base plane 4 on which the center C of the upper surface 21 is located.
[0041] The blade 3 has a height H (see Figure 4 The height H is the maximum distance from the tip 33 of the blade to the upper surface 21 of the seat 2, that is, the maximum vertical distance from the tip 33 of the blade to the base plane 4. The blade 3 has a width W, which is defined as the shortest distance from the leading edge 31 to the trailing edge 32 measured in a direction perpendicular to the main axis M. Therefore, the width W at a given distance D from the base plane 4 is measured in the plan view of the suction side 35 (or pressure side 34) as the length of a straight line parallel to the base plane 4, which connects a point L on the leading edge 31 to a point T on the trailing edge 32, however, points L and T have the same vertical distance D from the base plane 4.
[0042] exist Figure 3 In the top view shown, the width W of the blade 3 at a given distance D from the base plane 4 is the shortest distance from the leading edge 31 to the trailing edge 32 measured in a direction parallel to the base plane 4 and perpendicular to the main axis M.
[0043] As in Figure 4 As can be seen most clearly from the upper surface 21 of the base 2, the width W of the blade 3 first increases with the distance D from the base plane 4, reaching a maximum width WM, and then decreases as the distance D further increases toward the tip 33 of the blade.
[0044] According to the invention, the maximum width WM of the blade 3 is at least 55% of the height H of the blade 3, and preferably at least 65% of the height H of the blade 3. The optimal value for the maximum width WM depends on the corresponding application and on the absolute value of the height H of the blade 3. For many embodiments of the blade 3, more preferably, the maximum width WM is at least 70% of the height H, and more preferably at least 75% of the height H.
[0045] exist Figure 4In the embodiment shown, the maximum width WM of the blade 3 is approximately 80% of the blade height H.
[0046] When the blade 3 is used in the mixer 100, the relatively large maximum width WM of the blade 3 compared to its height H ensures high efficiency, reliable operation, and very good process results.
[0047] Preferably, the maximum width WM of the blade 3 is located at a distance DM from the base plane 4, where DM is between 40% and 70% of the height H of the blade 3. This area, between 40% and 70% of the height H, is... Figure 4 The blade is defined by lines L1 and L2. For most applications, it is preferable that when the maximum width WM is located at a distance DM from the base plane 4, the distance DM is between 50% and 60% of the height H of the blade 3, that is, the maximum width WM is preferably located in the upper half of the blade 3 (and...). Figure 4 (The meaning in the text is related). Figure 4 The height H of the blade 3 shown is approximately 340 mm, and the maximum width WM is approximately located at 57% of the height H.
[0048] Another preferred measure is as follows Figure 4 The embodiment of leading edge 31 and trailing edge 32 seen in the plan view. In this projection onto a plane perpendicular to the base plane 4, the blade 3 has a generally biconvex shape, except for a very small area immediately adjacent to the upper surface 21 of the seat 2. This means that the leading edge 31 and trailing edge 32 arch outward, that is, the edges 31 and 32 are convex essentially along their entire length.
[0049] For clarity, it should be mentioned that the terms “convex” and “concave” are used in their ordinary sense, that is, if a surface curves inward relative to the body, the surface of the body is called concave, and if a surface curves outward relative to the body, the surface is called convex.
[0050] As in Figure 4 As can be seen most clearly, the principal curvature of the leading edge 31 is greater than that of the trailing edge 32; that is, the leading edge 31 bends more than the trailing edge 32. For an explanation of the term "principal curvature," please refer to [reference needed]. Figure 6 , Figure 6 and Figure 4A similar plan view of the blade 3 is shown. Although the curvatures of the leading edge 31 and the trailing edge 32 do not change their corresponding algebraic signs, the curvatures are not constant over the entire length of the respective edges 31, 32. However, the curvature of the leading edge 31 can be approximated by a circle RL with radius R1, whereby R1 is chosen as the maximum radius of the circle that still conforms to the curvature of the leading edge. In the same manner, the curvature of the trailing edge 32 is approximated by a circle RT with radius R2. The corresponding radii R1 or R2 are then considered as the principal curvatures of the leading edge 31 or the trailing edge 32, respectively. The smaller the radii R1, R2, the stronger the curvature of the corresponding edges 31, 32. A preferred ratio between the principal curvature R1 of the leading edge 31 and the principal curvature R2 of the trailing edge 32 is such that the principal curvature R2 of the trailing edge 32 is at least 1.5 times, preferably at least 1.8 times, the principal curvature R1 of the leading edge 31. Figure 4 or Figure 6 In the illustrated embodiment, the ratio R2 / R1 is approximately 1.8. The radius R1 of the principal curvature of the leading edge 31 is approximately 140 mm.
[0051] As in Figure 3 The blade 3 is most clearly visible in the center, twisting around the main axis M. This twisting of the blade 3 can be described by the ridges of the different profiles of the blade 3. Each profile is a cross-section of the blade 3 cut in a plane parallel to the base plane 4, that is, perpendicular to the main axis M. Figure 7-9 Three different profiles were obtained at different distances D from the base plane 4. Figure 7 The outline of the blade 3 is shown at a distance D that is very close to the base plane 4 at a distance less than 1% of the height H. Figure 8 The outline of the blade 3 is shown at a distance D approximately halfway up the height H, and Figure 9 The outline of the blade 3 is shown at approximately 90% of the distance D at height H, near the tip 33 of the blade. Each outline is laterally defined by a first boundary line 6 and a second boundary line 7.
[0052] exist Figure 7 Neutralization Figure 8 The diagram shows the ridge line 5 of the corresponding contour. Ridge line 5 is the center line of the contour, and each point on it has the same distance from the boundary lines 6 and 7. (See diagram below.) Figure 7 Neutralization Figure 8 As indicated, ridge line 5 can be determined by inscribed circles in the contour, each circle contacting both the first and second boundary lines 6 and 7. Ridge line 5 is thus obtained by connecting the centers of these circles.
[0053] For example, especially through comparison Figure 7 and Figure 8 As can be seen, the ridge line 5 rotates counterclockwise around the main axis M as the distance D from the base plane 4 increases, which proves that the blade 3 twists around the main axis M.
[0054] As in Figure 7 and Figure 8 As can be seen, ridge 5 is not a straight line but a curve. At least for some contours, ridge 5 changes the algebraic sign of its curvature; that is, ridge 5 includes portions with positive curvature and portions with negative curvature.
[0055] To quantify the torsion of the blade 3 about the main axis M, the average direction of the corresponding ridge line 5 can be considered. The average direction of the ridge line 5 refers to the direction in which the ridge line 5 mainly extends. The average direction can be determined, for example, by approximating the corresponding ridge line 5 with a straight line.
[0056] Figure 9 The average direction of the ridge line 5 with two different profiles is shown. Figure 7 The average direction of the ridge line 5 of the outline shown is indicated by K1. Figure 9 The principal direction of the ridge line 5 of the shown profile is indicated by K2. That is, the principal direction K1 belongs to the profile of the adjacent seat 2. Figure 7 The principal direction K2 belongs to the profile near the tip 33 of the blade. The principal directions K1 and K2 define the torsion angle α to describe the torsion of the blade about the principal axis M. The torsion angle α is determined in the base plane 4, that is, the principal directions K1 and K2 are projected onto the base plane 4.
[0057] Preferably, in the contour near the base plane 4 ( Figure 7 The torsion angle α between the average direction K1 of the ridge line in the profile 5 near the tip 33 of the leaf blade and the average direction K2 of the ridge line 5 is at least 30°. Figure 9 In the embodiment of blade 1 shown, the torsion angle α is approximately 40°.
[0058] Viewed in a direction perpendicular to the main axis M of the blade 3, the pressure side 34 of the blade 3 (for example, see...) Figure 2 or Figure 8 The pressure side 34 includes convex and concave regions. In the middle region surrounding the main axis M, the pressure side 34 is convex. Moving towards the leading edge 31, the pressure side 34 becomes concave, and moving from the middle region towards the trailing edge 32, the pressure side also becomes concave, making the overall shape of the pressure side 34 concave with a convex region in the middle. As for the suction side 35, the dominant curvature of the suction side 35 is convex. In the region between the leading edge 31 and the main axis M, the suction side 35 is convex. In the region between the main axis M and the trailing edge 32, the suction side 34 becomes slightly concave, where "slightly" means that the dominant curvature of the suction side 35 remains convex.
[0059] Preferably, the seat 2 of the blade 1 is designed as a flange seat for adjustingly mounting the flange of the blade 1 to the hub 51 of the impeller 50 (see...). Figure 10That is, the relative orientation of the blade 1 with respect to the hub 51 is adjustable.
[0060] The reference shows the bottom view of blade 1. Figure 5 The seat 2 includes a plurality (four in this case) of arc-shaped elongated holes 23 arranged around the periphery of the adjacent disc seat 2. The elongated holes 23 are positioned in pairs with their diameters opposite each other. Two of the elongated holes 23 are located in front of the pressure side 34 of the blade 3, and two of the elongated holes 23 are located in front of the suction side 35 of the blade 3. Each elongated hole 23 can receive a screw 8 (see...). Figure 10 A hub 51 of the impeller 50 is used to secure the blade 1 to the impeller 50. Due to the arcuate shape of the elongated bore 23, the orientation of the corresponding blade 1 relative to the hub 51 is adjustable. To secure the blade 1 in the desired orientation, the lower surface 22 of the seat 2 includes a plurality of blind holes 24 arranged adjacent to the periphery of the disc seat 2, wherein all blind holes 24 are at the same distance from the center of the lower surface 22 of the seat 2. The hub 51 of the impeller 50 includes a locating pin (not shown) for each blade 1. When the blade 1 is mounted to the hub 51, the locating pin engages one of the blind holes 24, thus securing the blade 1 in the desired orientation.
[0061] Figure 10 A perspective view of an embodiment of an impeller 50 according to the present invention is shown. The impeller 50 includes a hub 51 and three identical blades 1 mounted to the hub 51 by flanges and fastened by screws 8. Each of the three blades 1 is designed as described above. The blades 1 are arranged at equal intervals about the periphery of the hub 51. The hub 51 includes three planar mounting surfaces 52 having substantially the same shape and size as the lower surface 22 of the seat 2. Figure 10 In the diagram, three mounting surfaces 52 are covered by the seat 2 of the blade 1. Each mounting surface 52 is arranged parallel to the axis A about which the impeller 50 rotates.
[0062] Depending on the specific application, the number of blades 1 of the impeller 50 may differ from three. In other embodiments of the impeller according to the invention, the impeller may, for example, include four blades.
[0063] As illustrated above with reference to an embodiment of the stirrer 100 according to the present invention Figure 1 As illustrated, the impeller 50 is mounted to one end of the drive shaft 60 of the agitator 100.
[0064] Figure 11 A preferred embodiment of the drive shaft 60 of the stirrer 100 is shown in cross-sectional view. Figure 11Only the portion of the drive shaft 60 between the mounting flange 80 and the impeller 50 is shown. The drive shaft 60 includes an inner shaft 61 extending in the direction of axis A and a sleeve 62 coaxially surrounding the inner shaft 61 and extending between the impeller 50 and the mounting flange 80. Adjacent to the mounting flange 80, the sleeve 62 is connected to another sleeve, for example, fixed relative to the inner shaft 61 by a shrink fitting. The sleeve 62 is sealed to the sleeve adjacent to the mounting flange 80 and sealed to the impeller 50, thereby preventing process fluid from entering the sleeve 62. Thus, the sleeve 62 protects the inner shaft 61 from any contact with the process fluid. Such contact could cause corrosion or other types of degradation of the inner shaft 61. An advantage of protecting the inner shaft 61 with the sleeve 62 is that the inner shaft 61 and the sleeve 62 can be made of different materials (typically metals), wherein only the sleeve 62 must resist corrosion or other degradation caused by the process fluid. Another advantage is that in the event of a deterioration of the sleeve 62, only the sleeve 62 needs to be replaced, while the inner shaft 61 can still be used.
[0065] Of course, in other embodiments, the drive shaft 60 may be designed as a bare shaft without the sleeve 62.
Claims
1. A blade for an impeller of a stirrer, the stirrer being used to mix or agitate process fluids, the blade comprising: A seat (2) for mounting the blade (1) to the impeller (50); and A blade (3) for mixing or agitating the process fluid, the blade (3) being connected to the seat (2), the blade (3) having a leading edge (31), a trailing edge (32), a blade tip (33), and a pressure side (34) and a suction side (35) extending from the leading edge (31) to the trailing edge (32), the blade tip (33) extending from the leading edge (31) to the trailing edge (32) at the end of the blade (3) opposite to the seat (2), and the blade (3) having a height (H) and a width (W), wherein, The blade (3) is connected to the base (2) in the base plane (4) and has a main axis (M) extending perpendicularly to the base plane (4) in a direction to the tip (33) of the blade, wherein the height (H) is the maximum distance from the tip (33) of the blade to the base (2), and wherein the width (W) is the distance from the leading edge (31) to the trailing edge (32), the width (W) being defined as the shortest distance from the leading edge (31) to the trailing edge (32) measured in a direction perpendicular to the main axis (M). The blade (3) has a maximum width (WM) that is at least 55% of the height (H). Both the leading edge (31) and the trailing edge (32) arch outwards. The characteristic feature is that, compared with the principal curvature of the trailing edge (32) extending from the seat (2) to the tip of the blade (33), the leading edge (31) extends from the seat (2) to the tip of the blade (33) with a greater principal curvature. The average direction of the ridge line (5) of the profile of the blade (3) parallel to the base plane (4) rotates around the main axis (M) as the distance (D) from the base plane (4) increases. The ridge (5) is curved such that the pressure side (34) is convex in the middle region around the main axis (M) and becomes concave from the middle region toward the leading edge (31) and toward the trailing edge (32), and the suction side (35) is convex.
2. The blade according to claim 1, wherein, The maximum width (WM) is at least 65% of the height (H).
3. The blade according to claim 2, wherein, The maximum width (WM) is at least 70% of the height (H).
4. The blade according to claim 3, wherein, The maximum width (WM) is at least 75% of the height (H).
5. The blade according to claim 1, wherein, The maximum width (WM) of the blade (3) is located in the region between 40% and 70% of the height (H) of the blade (3).
6. The blade according to claim 5, wherein, The maximum width (WM) of the blade (3) is located in the region between 50% and 60% of the height (H).
7. The blade according to claim 1, wherein, The principal curvature of the trailing edge (32) has a radius (R2) that is at least 1.5 times the radius (R1) of the principal curvature of the leading edge (31).
8. The blade according to claim 7, wherein, The principal curvature of the trailing edge (32) has a radius (R2) that is at least 1.8 times the radius (R1) of the principal curvature of the leading edge (31).
9. The blade according to claim 1, wherein, The average direction (K1) of the ridge line (5) near the base plane (4) and the average direction (K2) of the ridge line (5) near the tip of the blade (33) extend relative to each other at a twist angle (α) of at least 30°.
10. The blade according to claim 9, wherein, The torsion angle (α) is 40°.
11. The blade according to claim 1, wherein, The seat (2) is designed as a flange seat for mounting the blade (1) flange to the hub.
12. An impeller for an agitator used for mixing or stirring process fluids, comprising a hub (51) and a plurality of blades (1) mounted to said hub (51), wherein, Each blade (1) is designed according to any one of the preceding claims, and each blade (1) is mounted to the hub (51) by means of a corresponding seat (2).
13. The impeller according to claim 12, wherein, Each blade (1) is adjustablely mounted to the hub (51).
14. The impeller according to claim 12 or claim 13, having three blades (1).
15. A stirrer for mixing or stirring process fluids, comprising: Impeller (50), which is used to stir or mix process fluids; A drive unit (70) for rotating the impeller (50); and a drive shaft (60) that connects the impeller (50) to the drive unit (70), characterized in that the impeller (50) is designed according to any one of claims 13 to 15.
16. The agitator according to claim 15, having a mounting flange (80) for securing the agitator (100) to the wall of a container for the process fluid, wherein, The drive shaft (60) includes an inner shaft (61) and a sleeve (62) coaxially surrounding the inner shaft (61) and extending between the hub (51) of the impeller (50) and the mounting flange (80), wherein the sleeve (62) is designed such that when the agitator (100) is mounted to the wall of the container, the sleeve (62) prevents the inner shaft (61) from contacting the process fluid.
17. The stirrer according to claim 15 or claim 16, wherein, The agitator is designed to be mounted horizontally to the wall of the container used for the process fluid.