DEVICE FOR ADDING AND MIXING AN ADDITIVE INTO A HYDRAULICALLY SETTABLE MIXTURE

Abstract

A device for adding and mixing an additive into a hydraulically settable mixture includes a tubular cavity for conducting the hydraulically settable mixture through in an intended flow direction, wherein a static flow-influencing element, in which there is an aperture that leads into the cavity and is intended for introducing the additive, projects into the cavity.

Claims

1. A device for adding and mixing an additive into a hydraulically settable mixture, comprising a tubular cavity for conducting the hydraulically settable mixture through in an intended flow direction, wherein a static flow-influencing element, in which there is an aperture that leads into the cavity and is intended for introducing the additive, projects into the cavity.

2. The device as claimed in claim 1, wherein the aperture leading into the cavity is configured in such a way that the additive can be introduced into the cavity at a distance from a wall of the cavity.

3. The device as claimed in claim 1, wherein the aperture leading into the cavity is configured in such a way that the additive can be introduced into the cavity on a downstream side of the flow-influencing element.

4. The device as claimed in claim 1, wherein the flow-influencing element has a leading edge extending into the cavity inclined with respect to the flow direction from its upstream end to its downstream end.

5. The device as claimed in claim 1, wherein the flow-influencing element is in the form of a fin.

6. The device as claimed in claim 5, wherein the fin is inclined with respect to a longitudinal axis of the cavity, with the result that lateral surfaces of the fin are inclined with respect to the longitudinal axis of the cavity, and/or wherein the fin is curved.

7. The device as claimed in claim 5, wherein a leading edge of the fin is at an angle of 20-60° with respect to the longitudinal axis of the cavity and/or the trailing edge is at an angle of 80-90° with respect to the longitudinal axis of the cavity.

8. The device as claimed in claim 1, wherein there are at least two flow-influencing elements spaced apart from one another in a longitudinal direction of the cavity.

9. The device as claimed in claim 8, wherein the radial directions of the at least two flow-influencing elements are at an angle of 360°/(number of flow-influencing elements).

10. The device as claimed in claim 8, wherein the device comprises at least two individual devices for adding and mixing an additive into a hydraulically settable mixture, comprising a tubular cavity for conducting the hydraulically settable mixture through in an intended flow direction, wherein a static flow-influencing element, in which there is an aperture that leads into the cavity and is intended for introducing the additive, projects into the cavity, that can be detachably connected to one another, wherein the devices are designed in such a way that they communicate with one another in the connected state by way of their tubular cavities.

11. An arrangement comprising at least one device as claimed in claim 1,wherein attached to the downstream side there is a first pipe portion that tapers in the flow direction with respect to the internal cross section, wherein the internal cross section in the first pipe portion has a conical taper, and wherein attached to the upstream side there is a second pipe portion tapering counter to the flow direction with respect to the internal cross section, wherein the second pipe portion tapers in a stepped manner.

12. A method comprising using the device as claimed in claim 1 in the production of shaped bodies by additive manufacture and/or in the application of spray concrete or spray mortar.

13. A process for adding and mixing an additive into a hydraulically settable mixture, by means of a device or an arrangement as claimed in claim 11, wherein the additive is introduced into the hydraulically settable mixture through the aperture leading into the cavity.

14. The process as claimed in claim 13, wherein the additive is added by means of a device for adding and mixing an additive into a hydraulically settable mixture, comprising a tubular cavity for conducting the hydraulically settable mixture through in an intended flow direction, wherein a static flow-influencing element, in which there is an aperture that leads into the cavity and is intended for introducing the additive, projects into the cavity, wherein there are at least two flow-influencing elements spaced apart from one another in a longitudinal direction of the cavity and wherein a first partial quantity of the additive is added through a first flow-influencing element, while at the same time at least one further partial quantity is added through at least one further one of the flow-influencing elements.

15. The process as claimed in claim 13, wherein the apertures leading into the cavity are subjected to and/or blown dry by a gas after the additive has finished being introduced.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0086] In the drawings that are present for the purpose of explaining the exemplary embodiments:

[0087] FIG. 1 shows a perspective view of a device according to the invention for adding and mixing an additive into a hydraulically settable mixture, having a curved, triangular fin as flow-influencing element;

[0088] FIG. 2 shows a view of the downstream side of the device from FIG. 1;

[0089] FIG. 3 shows a section along the line B-B from FIG. 2;

[0090] FIG. 4 shows a plan view of the device from FIGS. 1-3 in the direction of the fluid inlet through which an additive can be fed in;

[0091] FIG. 5 shows a schematic depiction of an arrangement having a device from FIGS. 1-4, wherein a pipe portion with a conical taper in the flow direction with respect to the free internal cross section is attached to the downstream end, and a second pipe portion tapering counter to the flow direction in a stepped manner is attached to the upstream end,

[0092] FIG. 6 shows a further arrangement comprising a set of four structurally identical and mutually connected devices, as depicted in FIGS. 1-4, with pipe portions attached thereto;

[0093] FIGS. 7a-d show variants of the invention having flow-influencing elements in the form of circular-cylindrical stubs, trapezoidal fins and rectangular fins with differently arranged apertures for introducing an additive.

EXAMPLES

[0094] FIGS. 1-4 show a device 100 according to the invention for adding and mixing an additive into a hydraulically settable mixture.

[0095] As can be seen from FIG. 1, the device 100 is present in the form of a circular-cylindrical pipe portion with a circular-cylindrical cavity 130, through which a hydraulically settable mixture can be conducted along the longitudinal axis 131 (see FIG. 3), which corresponds to the intended flow direction. There is a first annular fastening flange at the downstream end 110, while there is a second annular fastening flange at the upstream end 120. The device 100 can be attached to further tubular elements via the flanges.

[0096] A triangular and curved fin 150 in the form of a flow-influencing element projects into the cavity 130 from the inner wall of the device 100. An aperture 160 that leads into the cavity 130 and is intended for introducing an additive is arranged on the downstream trailing edge 150c of the fin 150.

[0097] The additive can be conducted from the outside to the aperture 160 through a fluid inlet 140 in the region of the fin 150 and a fluid channel 151 (see FIG. 3) running through the fin 150.

[0098] FIG. 2 shows a plan view of the downstream end 110 of the device 100. As can be seen from FIG. 2, the fin 150 is curved along its entire height, or in a radial direction. It includes a convex side 150d (visible in FIG. 2) and an oppositely situated and concavely curved lateral surface 150b (hidden in FIG. 2; see FIG. 4). The aperture 160 for introducing the additive is at a distance of approximately half of the diameter 132 from the wall of the circular-cylindrical cavity 130. The diameter 132 is for example approximately 150 mm.

[0099] In FIG. 3, which shows a section along the line B-B from FIG. 2, the triangular shape of the fin 150 can be seen. The fin 150 has a leading edge 150a running into the cavity 130 from the upstream end 120 in an inclined manner. The angle 152 between the leading edge 150a and the longitudinal axis 131, or flow direction, is for example approximately 30°. In this way, the fin 150 as flow-influencing element projects continuously to an increasing extent into the cavity 130 along its length running in a longitudinal direction 131 of the cavity 130.

[0100] The trailing edge 150c already depicted in FIGS. 1 and 2, which is approximately perpendicular with respect to the longitudinal axis 131, runs in the region of the downstream end of the fin 150.

[0101] A fluid channel 151 runs through a bore in the wall of the device 100 and inside the fin 150 from the fluid inlet 140, parallel to the trailing edge 150c, as far as the vertex of the fin 150. In the region of the vertex of the fin, the direction of the fluid channel 151 changes by 90°, with the result that the additive 141 to be poured in can be introduced into the cavity 131 in a direction with a main component along the longitudinal axis 131.

[0102] FIG. 4 shows a plan view of the device 100 in the direction of the fluid inlet 140. It can be seen here that the fin 150 runs in a direction 153 inclined with respect to the longitudinal axis 131 of the cavity in the region of the wall of the cavity 130, wherein the direction 153 is at an angle 153 of approximately 5° with respect to the longitudinal axis 131 of the cavity 130.

[0103] The aperture 160 is configured in such a way that a flow of additive leaving it runs in a direction 162 inclined with respect to the longitudinal axis 131 of the cavity. Specifically, the configuration is such that the additive can be introduced into the cavity in a direction 162 running at an angle of approximately 30° with respect to the longitudinal axis 131 of the cavity 130.

[0104] FIG. 5 shows a schematic depiction of an arrangement having a device 100 from FIGS. 1-4, wherein a pipe portion 200 with a conical taper in the flow direction 133 with respect to the free internal cross section is attached to the downstream end 110. The pipe portion 200 has for example a length of 1 m. In the region of its upstream end, the internal diameter of the pipe portion 200 corresponds to the diameter 132 of the cavity 130 of the device 100 of approximately 150 mm, while the internal diameter of the pipe portion in the narrowest region, or in the region of its downstream end, is approximately 100 mm.

[0105] A second pipe portion 300 tapering counter to the flow direction 133 in a stepped manner is furthermore attached to the upstream end 120 of the device 100. In the region of its end connected to the device 100, the internal diameter of the pipe portion 300 corresponds to the diameter 132 of the cavity 130 of the device 100 of approximately 150 mm, while the internal diameter of the pipe portion 300 in the tapered region, or in the region of its upstream end, is approximately 100 mm.

[0106] FIG. 6 shows a further arrangement comprising a set 400 of four structurally identical devices 100 according to the invention that are connected to one another. The second, third and fourth ones of the devices according to the invention are provided with the reference signs 100′, 100″, 100‴.

[0107] The four devices 100, 100′, 100″, 100‴ are detachably connected to one another over the respective flanges on the devices via clamps, with the result that a continuous cylindrical cavity is produced. In this respect, the second device 100′ has been rotated by 90° about the longitudinal axis with respect to the first device 100, with the result that the fin 150′ of the second device 100′ is at an angle of 90° with respect to the fin 150 of the first device 100. The third device 100″ has been correspondingly rotated by a further 90° with respect to the second device 100′ and the fourth device 100‴ in turn by a further 90° with respect to the third device 100″. In this way, all the fins 150, 150′, 150″, 150‴ point radially in four directions differing by 90°, while at the same time being spaced apart from one another in a longitudinal direction of the cavity.

[0108] It is possible to introduce, for example, partial flows of an additive, e.g. a solidification accelerator, into the cavity, or a hydraulically settable mixture conducted therethrough, through the fluid inlets 140, 140′, 140″, 140‴ of the four devices 100, 100′, 100″, 100‴. However, it is also possible to introduce a different additive at each of the fluid inlets 140, 140′, 140″, 140‴.

[0109] FIGS. 7a-7d show variants of the invention having differently configured flow-influencing elements. In FIG. 7a, the flow-influencing element is a circular-cylindrical stub 150.1, which, in the region of its free end on the lateral surface, has an aperture 160.1 for introducing an additive.

[0110] In the variant of FIG. 7b, the flow-influencing element is formed as a fin 150.2 in the form of a right-angled trapezoid, wherein the aperture 160.2 for introducing the additive is present on the downstream trailing edge.

[0111] FIG. 7c shows a variant having a rectangular fin 150.3. In this case, the aperture 160.3 for introducing the additive is located on the bottom side of the fin, with the result that the fluid can be introduced into the cavity in a radial direction.

[0112] In FIG. 7d, the flow-influencing element is a fin 150.4 in the form of a universal trapezoid without a right angle. In this case, the additive can be introduced through three apertures 160.4. Two of the apertures are located at different heights on the downstream trailing edge and one aperture is located on the lateral surface.

[0113] Further, tests with different arrangements were carried out to investigate the influence of the flow-influencing elements.

[0114] Experiment 1: A concrete composition was pumped at a constant throughflow rate through an arrangement as depicted in FIG. 6. In the process, a hardening accelerator modified with red dye was added and mixed in at a constant feed rate through the inlets 140, 140′, 140″, 140‴. The mixture created in this way was filled into a test tube attached to the pipe portion 200 and allowed to harden. After the hardening had taken place, the concrete body located in the test tube was transversely cut open and the cross sectional area was optically analyzed.

[0115] Experiment 2: The procedure took place as for Experiment 1. However, the fins 150, 150′, 150″, 150‴ were replaced by uncurved fins that had the same dimension and were aligned parallel to the longitudinal axis, or had no inclination.

[0116] Experiment 3: The procedure took place as for Experiment 1. However, the fins 150, 150′, 150″, 150‴ were replaced by flow-influencing elements as depicted in FIG. 7a.

[0117] Experiment 4: The procedure took place as for Experiment 1. In this case, the fins 150, 150′, 150″, 150‴ were completely removed, with the result that the accelerator was introduced only through bores in the wall of the devices 100, 100′, 100″, 100‴.

[0118] All experiments were carried out under identical conditions, except for the different flow-influencing elements.

[0119] The homogeneity of the distribution of the red dye, which constitutes a degree of distribution of the hardening accelerator, was optically assessed.

[0120] Specifically, the ratio of dyed cross-sectional area to non-dyed cross-sectional area was determined and evaluated on a scale of 1 (poor) to 6 (very good). Table 1 gives an overview of the results obtained.

TABLE-US-00001 Test results Experiment Flow-influencing element Evaluation 1 Curved, inclined triangular fin 5.33 2 Uncurved and straight triangular fin 5.25 3 Circular-cylindrical stub 4.83 4 - 2.96

[0121] The test results show that the addition and mixing in according to the invention of an additive with the aid of flow-influencing elements results in a significantly more homogeneous distribution of the additive for a hydraulically settable composition in comparison with conventional solutions (experiment 4). Particularly advantageous in this respect are flow-influencing elements in the form of fins (experiments 1 and 2), in particular when they are curved and inclined (experiment 1).

[0122] The arrangements according to the invention were furthermore utilized in additive manufacturing processes as described in EP 3 558 679 A1 and successfully tested. Similarly, the arrangements according to the invention were successfully tested for the purpose of applying spray concrete in processes as described in WO 2015/034438 A1.

[0123] However, the exemplary embodiments presented above should not be understood as having a limiting effect and can be modified as desired within the scope of the invention.