EP1758672A1

EP1758672A1 - Mixing device and method for introducing an additive into a pumpable mixture

Info

Publication number: EP1758672A1
Application number: EP05752749A
Authority: EP
Inventors: Alexander Bleibler; Cyrill Spirig; Alexander Stücheli
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2004-05-28
Filing date: 2005-05-30
Publication date: 2007-03-07
Also published as: EP1600205A1; WO2005115600A1

Abstract

In a mixing device (6) for the introduction of an additive into a pumpable mixture (10) with a plastic-viscose behaviour, in particular concrete, the mixture is transported in a conduit (4, 8). At least one injection element (14, 14', 14a) is situated in the conduit (8) for introducing the additive (5) into the mixture (10). A mixing chamber (9), in which the additive (5) is dynamically mixed with the plastic-viscose mixture (10), is located downstream.

Description

Mixing device and method for adding an additive to a pumpable mixture

Technical field

The invention is based on a mixing device according to the preamble of the first claim.

The invention is also based on a method for adding an additive to a pumpable mixture according to the preamble of the independent method claim.

State of the art

Mixing in small amounts of a substance, e.g. of an additive in a mixture with plastic-viscous behavior occurs in many applications. However, thorough mixing is often difficult to achieve.

For example, a static mixer is used to mix an additive, such as an activator with fine mortar. If you also use such static mixers on conventional concrete, the static mixer becomes blocked due to the coarse gravel content and the mixer can even be destroyed.

The addition of the activator to the ready-mixed concrete and the mixing is therefore often already carried out in the vehicle drum. The activator liquefies the concrete and starts the setting mechanism. The disadvantage is that after the activator has been added to the concrete in the vehicle drum, not much time must pass before the activated concrete is processed in the building, otherwise it will harden beforehand.

Presentation of the invention

The invention is based on the object of specifying, in a mixing device and a method of the type mentioned at the outset, a mixing device which makes it possible to introduce additives rapidly into a plastic-viscous mixture and to achieve thorough mixing.

According to the invention, this is achieved by the features of the first claim.

The essence of the invention is therefore that at least one in a line

Injection means for adding additive is arranged in the mixture that a mixing space is arranged downstream, in which the additive is dynamically mixed with the plastic-viscous mixture.

The advantages of the invention can be seen, inter alia, in the fact that good mixing of the plastic-viscous mixture and additive is achieved. This with a relatively short mixing section and that the mixing can be carried out shortly before the processing location. The one shown here The method and the device are particularly suitable for the continuous addition and mixing of very small amounts of chemical additives into a pumpable mixture with plastic-viscous behavior, in particular into a granule-suspension mixture such as concrete.

Further advantageous embodiments of the invention result from the subclaims.

Brief description of the drawing

In the following, embodiments of the

Invention explained in more detail. Identical elements are provided with the same reference symbols in the various figures. The direction of flow of the media and the direction of rotation of the elements of the device are indicated by arrows.

Show it:

Figure 1 shows schematically the processing of concrete in a building.

2 shows schematically the mixing device according to the invention; 3a schematically means for rough distribution for the additive;

3b shows a detailed illustration of the injection means for the additive from FIG. 3a;

4a schematically further means for rough distribution for the additive;

4b shows a detailed illustration of the injection means for the additive from FIG. 4a;

4c shows a detailed illustration of the injection means for the additive from FIG. 4a;

4d schematically the admixture distribution in the mixture; 5 schematically shows an embodiment of the mixing room;

6 shows a mixing element with injection means for the additive in partial cross section; 7 schematically possible mixing elements; 8 schematically shows a further embodiment of the mixing room; 9 schematically shows a further embodiment of the mixing room with several mixing shafts; Fig. 10 mixing with two waves corresponding to Fig. 9; 11 schematically shows a further embodiment of the mixing room.

Only the elements essential for the immediate understanding of the invention are shown.

Way of carrying out the invention

1 schematically shows the processing of a plastic-viscous mixture, here of concrete 10 in a building. Concrete is delivered to the construction site by means of a transport vehicle 1. It is not shown that the concrete is usually transported in a rotating drum mounted on the transport vehicle. This concrete was treated in the concrete plant with additives that the hydration or

The setting mechanism is delayed by several hours. This concrete generally corresponds to a pumpable granulate-suspension mixture with plastic-viscous behavior. The concrete 10 is temporarily stored in a container 2 or pumped directly from the vehicle to the construction site using a pump 3 and a line 4 under pressure. Such a line can be used to transport the concrete over several 100 meters or even a few kilometers. Prior to the processing of the concrete 10, it must be processed by adding additives 5 (also additive called) how activators, such as a setting accelerator, are reactivated. The addition of the additive takes place in a mixing device 6. Further substances can be supplied via a further line 7, for example water, concrete from another source, etc. The concrete 10 'mixed with the additive 5 is then correspondingly on the construction site at the processing site 20 processed. The processing of the concrete can be carried out by any method, for example by spraying, pouring, etc. The distance from the mixing device to the processing site is in itself arbitrary, but is advantageously chosen to be as short as possible so that as little waste is generated or activated concrete in the line remains and may make it unusable. With the present mixing device, it is also possible to fill the line from the mixing device to the processing location with non-activated concrete 10 by no longer adding any activator in the mixing device. This prevents the line from becoming blocked. The mixing device shown here allows small

Add and add amounts of additive to the plastic-viscous mixture, especially in a ratio of 1: 100 to 1: 1000.

2, the mixing device 6 is shown in more detail. This mixing device 6 comprises a feed line 8 and a mixing space 9. The diameter of the mixing space 9 is advantageously larger than that of the feed line 8 in order to reduce the flow rate through the mixing space. The mixing chamber is preferably shaped cylindrically because of the high pressures and can have a small volume of less than 100 liters. The present mixing process is preferably carried out as an inline mixing process which is under pressure. In the feed line 8, which is preferably angled, means 11 for roughly distributing the additive 5 in the concrete 10 are arranged. A mixing element (not shown) is arranged in the mixing chamber and can be driven by a drive 13 via a shaft 12. Additional admixture 5 can be introduced into the concrete through the shaft 12 and the mixing element arranged in the mixing chamber 9. Additive 5 can also be used in the initial area of the mixing chamber 9 are injected, wherein the injection means to be used can be shaped analogously to the injection means 14, 14a. The additive can thus be introduced simultaneously at several points over the line cross-section and homogeneously distributed or mixed both axially and radially through the downstream mixing space. This results in a homogeneous distribution of the admixture in the concrete 10 'at the end of the mixing room, so that the concrete is activated evenly. Bending the feed line has several advantages. The bend allows the drive and the shaft for the mixing chamber to be arranged on one axis without the mixture flow being impeded. In addition, injection means 14a can be arranged in the bend, via which additive can be introduced into the edge region of the pumped concrete despite the lubricating layer in the edge region. The additive 5 is advantageously added at the same or a higher flow rate than that of the concrete. The relative speed of the admixture is then greater than zero compared to the concrete. This ensures a safe injection of the additive and that the nozzles to be used for the injection do not become blocked.

The means 11 for the rough distribution of the additive are shown in more detail in FIG. 3a. The additive 5 is introduced into the concrete by means of several nozzles 15 via injection means 14 arranged in the feed line 8. The injection means 14 are shown in FIG. 3 as tubes with bores as nozzles 15, but can also be shaped differently. The injected additive 5 forms threads in the concrete pumped through the line. These threads are shown in cross section under II) of FIG. 3. Since the concrete corresponds to a pumpable granule-suspension mixture with plastic-viscous behavior, the Reynolds number Re of the concrete in the pipe is approximately in a range from Re = 1 to 1000, so the flow is laminar, creeping. This means that the additive is not caused by turbulence is mixed, but remains as a "thread" for a long time. The injection means 14, 14a arranged over the line length and cross-section place several "threads" distributed over the cross-section in the laminar concrete flow. Since mixtures such as concrete create a smear layer on the edge of the cross-section of the line and because of the rheological properties of the concrete, the additive is advantageously added over the entire cross-section and not at the edge so that the additive can be introduced into the concrete.

According to FIG. 3 b, the nozzles 15 in the injection means 14 are preferably arranged such that the additive is injected in the flow direction of the concrete 10. As a result, the nozzles 15 are not blocked by the concrete and the additive added forms a thread-like structure in the concrete and does not remain in the lubricating layer, as would happen when it was added via wall openings in the feed line 8.

4 a further means 11 for the rough distribution of the additive are shown. The feed line 8 has an extension in which an injection means 14 'is arranged. The injection means 14 'serves as a flow divider which divides the concrete stream 10 into two parts. The additive 5 is introduced into the concrete at the downstream end of the injection means 14 'by means of several nozzles 15, see FIGS. 4b, 4c. The injection means 14 'has an essentially elliptical cross section with sharp leading and trailing edges. This injection means 14 'is built relatively solid, for example to be able to withstand stones in the concrete and thus prevent damage to the injection means. The cross section of the feed line 8 is expanded in accordance with the dimensions of the injection means, so that the concrete flow flows evenly and the flow of the concrete is influenced as little as possible. If desired, the cross-section can also be adjusted so that in the area of Injection of the additive accelerates or slows the flow.

In addition, injection means 14a can also be arranged here in the edge region of the feed line, in the region of the nozzles 15, in order to spray additives in the edge region.

4b and 4c, the injection means 14 'can be aligned differently in the feed means 8. In particular if a plurality of injection means 14 'are arranged in series in the feed means 8, it is advantageous to align them differently in the feed means, as is shown schematically in FIGS. 4b and 4c.

4d shows the admixture distribution in the concrete downstream of two injection means 14 'corresponding to FIGS. 4b and 4c. There is a good distribution of the admixture in the concrete, which can be further improved by additional injection means.

The addition of additives via the injection means 14, 14 ', 14a is advantageously carried out in such a way that the additive volume flow is adapted everywhere proportionally to the volume flow of the granule-suspension mixture, and thus the same amount of additive is distributed over the entire cross section. This means that less additive is added on the margins than in the middle area of the line. This is because the granulate-suspension mixture has a much lower flow velocity at the edge than in the middle. Adding the same amount of additive immediately on the edge would cause the additive to accumulate on the edge opposite the central area of the line.

5 shows the mixing space 9 in detail. In the mixing chamber, several stages of mixing elements 16 are arranged on the shaft 12 in the direction of flow, but only one mixing element can also be used. The shaft 12 is set in rotation via the drive, not shown here that the thread-like admixture already added is cross-mixed in the concrete. The shape of the mixing elements is arbitrary per se, with some possible embodiments being described in the following FIG. 7. Additive 5 can also be fed into the concrete directly via the mixing elements 16, the nozzles being shaped analogously to the injection means. The addition of the additive takes place via the shaft 12. Static mixing elements 17 can also be arranged at the edge of the mixing space 9, which support the mixing process of the mixing elements 16. The number, shape and position of the static mixing elements 17 mounted on the wall or also inside are such that they do not cause blockage. In addition, the static mixing elements 17 prevent offsets.

The shaft 12, which is supported by a bearing 12a, does not necessarily have to lie on the central axis of the line 8, but in individual cases can also be arranged next to the central axis for better mixing, as is symbolized in the figure by the double arrow.

6 shows a mixing element 16 in detail. The shaft 12 and the mixing element 16 have bores through which the additive 5 is directed to nozzles 15 through which the additive exits. Here, too, the nozzles 15 are preferably arranged in the mixing element 16 such that the admixture is injected in the flow direction of the concrete 10. As a result, the nozzles 15 are not blocked by the concrete. The nozzles can of course be arranged over the entire radial extent of the mixing element 16 or only over certain partial areas.

The nozzles do not have to be arranged symmetrically either, so that the mixing can be improved depending on the design by a certain asymmetry.

7 shows some different possible embodiments of mixing elements 16. These are a) propeller stirrers, b) Disc stirrer, c) toothed disc stirrer, d) inclined blade stirrer, e) impeller stirrer, f) anchor stirrer, g) grid stirrer or blade stirrer, h) cross bar stirrer, i) MIG stirrer and k) spiral stirrer. In principle, these types of mixing elements can be used alone, in combination or in a modification. However, the mixing element should preferably be designed such that it generates as little resistance as possible in the concrete.

8 shows a further embodiment of the mixing space 9. Several stages of mixing elements 16 are arranged as spiral stirrers in the mixing chamber on the shaft 12. Additive 5 is added to the concrete during the transverse mixing via the shaft 12 and the mixing elements 16. This configuration of the mixing element generates little resistance in the concrete and allows the admixture to be mixed evenly. Of course, when using a spiral stirrer, two or more nested spiral stirrers can also be used, so that the mixing is improved and the addition of additives over the entire cross section is made possible.

FIG. 9 shows a further embodiment of a mixing room 9. Two shafts 12 with several stages of mixing elements 16 are arranged in the flow direction in the mixing space. The two shafts 12 preferably rotate against each other and the mixing elements can interlock, but if possible without touching one another. The intermeshing of the mixing elements is shown in detail in FIG. 10. The effect of this mixture, i.e. stretching and folding, or the fine distribution of the admixture in the concrete, is shown schematically on the right. Of course, any number of additional waves can be used.

A further embodiment of the mixing space 9 is shown in FIGS. 11a and 11b. The shaft 12 'for driving the mixing elements 16' is not in here Mixing room arranged, but outside. Mixing elements 16 'rotating around the mixing space are driven by means of the shaft 12', which is driven by a drive 13. The drive is advantageously carried out via gearwheels 18 arranged on the shaft 12 ', which mesh with the ring gear 19 of the mixing elements 16'. The actual mixing elements protrude into the concrete conveyed through the mixing room and mix the concrete and the admixture, especially in the edge area. The extent to which the mixing elements protrude must be adapted to the particular circumstances, such as, for example, the plastic-viscous mixture, the geometry of the mixing room, etc. Additive 5 can also be added to the concrete here during the transverse mixing via the mixing elements 16 '. This configuration of the mixing element generates little resistance in the concrete and allows the admixture to be mixed evenly.

Of course, the invention is not limited to the exemplary embodiment shown and described. Instead of the activator, any additives or other substances can be used which are to be mixed into a plastic-viscous mixture in relatively small amounts. The plastic-viscous mixture to be used is also arbitrary in itself. Thus, such mixing devices as described above can be used not only for mixing admixtures into concrete, but also wherever something has to be mixed into a mixture with plastic-viscous behavior. Fields of application are therefore in the construction industry, oil refining, pyrometallurgical addition in the extraction of metals from ores, alloys of metals, pasta production, incorporation of additives in doughs, e.g. nuts in bread, introduction of berries etc. in yogurt, plastic processing, emulsifying aromatic oils in various foods, honey processing, chemical industry, pharmaceutical industry, colorant industry, etc. In particular when producing ceramics by means of slip casting, the slips are transported to the ceramic factory and a thyxotropic agent is added to the slip before casting. LIST OF REFERENCE NUMBERS

Transport vehicle container pump line admixture / activator mixing device line supply line mixing room concrete delayed 'concrete activated means for coarse distribution shaft' Wellea bearing shaft drive injection means' injection meansa injection agent nozzles mixing element 'mixing element static mixing elements gear on shaft sprocket 16' processing location

Claims

claims

1. Mixing device (6) for admixing an additive in a pumpable mixture (10) with plastic-viscous behavior, in particular concrete, the mixture being conveyed in a line (4, 8), characterized in that in the line (8) at least one injection means (14, 14 ', 14a) for adding additive (5) to the mixture (10) is arranged, and that a mixing space (9) is arranged downstream, in which the additive (5) with the plastic-viscous Mixture (10) is mixed dynamically.

2. Mixing device according to claim 1, characterized in that at least one rotatable mixing element (16) is arranged in the mixing space.

3. Mixing device according to claim 2, characterized in that the mixing element (16) is arranged on a shaft (12) and that the drive (13) of the shaft is arranged axially to the shaft.

4. Mixing device according to claim 2 or 3, characterized in that the rotatable mixing element (16) is a helical stirrer.

5. Mixing device according to claim 2, 3 or 4, characterized in that the mixing element (16) has means for adding additive (5) to the mixture (10).

6. Mixing device according to one of the preceding claims, characterized in that at least one static mixing element (17) is arranged in the mixing space.

7. Mixing device according to one of the preceding claims, characterized in that the injection means (14, 14 ', 14a) are arranged in the flow of the plastically viscous mixture (10).

8. Mixing device according to one of the preceding claims, characterized in that the injection means (14, 14 ', 14a) have nozzles (15) which are directed essentially downstream.

9. Mixing device according to one of the preceding claims, characterized in that the line (8) arranged upstream of the mixing space (9) is angled.

10. Mixing device according to one of the preceding claims, characterized in that the pumpable mixture (10) with plastic-viscous behavior is a granule-suspension mixture such as concrete.

11. A method for adding an additive (5) to a pumpable mixture (10) with plastic-viscous behavior, in particular concrete, the mixture being conveyed in a line (4, 8), characterized in that that the additive (5) is added to the pumpable mixture (10) via at least one injection means (14, 14 ', 14a) and is then mixed in a downstream dynamic mixing chamber in the pumpable mixture (10).

12. The method according to claim 11, characterized in that the additive (5) by means of the injection means (14, 14 ', 14a) is added at several locations distributed over the cross section of the line.

13. The method according to claim 11 or 12, characterized in that additive (5) is added in the dynamic mixing room.

14. The method according to claim 13, characterized in that the additive (5) is added via at least one mixing element (16) arranged in the mixing space.

15. The method according to claim 14, characterized in that the additive (5) via the shaft of the mixing element (16) is conveyed to the mixing element.