EP1857172A1 - Static mixer - Google Patents

Abstract

A static mixer comprises a housing (1) including an inlet opening having a first cross-section in a plane normal to a main direction of flow in the inlet opening and an outlet opening having a second cross-section in a plane normal to the main direction of flow in the outlet opening and larger than the first cross-section; and a mixing element (12) having flow-dividing layers (3, 4) and defining a cross-sectional development increasing substantially continuously from the first cross-section to the second cross-section.

Description

The invention relates to a mixing element for a static mixer according to the preamble of claim 1 and uses of such a mixing element and a static mixer with such a mixing element. Static mixers are used for mixing two or more fluid components, in particular of gas-liquid mixtures. In particular, the mixing element should find use in a designed as a diffuser section fluid conducting means. The mixing element contributes at least to the maintenance of a uniform state of mixing in the diffuser, by counteracting any possible demixing effects through its structural design and / or effecting a uniform mixing of the components flowing through the diffuser section. The static mixer thus comprises the fluid-conducting means having an inlet opening for the components of a first diameter and an outlet opening for the mixture of a second diameter, wherein the fluid-conducting means has a diameter profile which increases substantially continuously from the first diameter to the second diameter, and at least a mixing element arranged in the diffuser section. In particular, the fluid-conducting means can be configured as a line piece that widens substantially continuously.

From the prior art is according to EP-A-918 146 known to provide internals in a diffuser expanding as a mixer housing. These installations are formed of concentric frustoconical lateral surfaces. The conical tips are at least approximately at a point and the inlet cross sections of the internals span with their edges in each case a surface which has a shape that tapers against the flow direction. Through the internals through the diffuser flowing gases, in the case of EP-A-918146 Pollutants, passed more evenly into a downstream catalyst.

In the facility for the reduction of pollutants according to EP-A-918 146 When passing through the gases, so-called edge effects occur, which are also referred to as channeling. These edge effects are caused by edge currents, which cause a slowing of the flow relative to the center. These edge flows are mainly due to frictional effects on the inner wall of the diffuser. When widening in the cone, the braking effect, caused by the above-mentioned frictional effects, can lead to a reduction of the velocity in the area close to the wall, which can even lead to the drop response. bubble-shaped, ie disperse phase, in particular liquid constituents, can no longer keep in suspension with the continuous phase, in particular a gas) and separate.

Such gas-liquid mixtures are used for example in the LNG (liquid natural gas) processing as a coolant. This coolant consists of various gaseous and liquid components, the proportion in particular volatile aliphatic hydrocarbons, preferably methane, ethane, propane and / or butane comprises. For cooling, the coolant is introduced into a heat exchanger, which is generally designed as a tube bundle heat exchanger. The heat exchanger is designed for a cooling capacity that requires a homogeneous coolant mixture, otherwise the cooling capacity can not be optimally utilized. Accordingly, if there is a separation of the coolant mixture, the desired cooling capacity may not be reached and the required capacity can not be maintained. So far, you had to oversize the heat exchanger accordingly.

So far, the solution to the problem with static mixers was the fact that common static mixers could not be adapted to a substantially continuously expanding piece of duct.

As a solution has offered to use a static mixer of two cylindrical mixing elements, wherein one of these mixing elements respectively the diameter of the supply line, ie a pipe, and the second mixing element, the diameter of the Having heat exchanger inlet. Measurements on such a static mixer have shown that even in this case, the gaseous and liquid components are not evenly distributed. The mixing section is dimensioned too short for this purpose, also in this mixer arrangement, there is an abrupt transition at the point where the cylindrical mixing element with the diameter of the supply line adjoins the mixing element with the diameter of the heat exchanger inlet. In the present case, the two mixing elements are preferably made in the same length, so that the transition is in the middle.

The object of the invention is to provide a mixing element for a static mixer, by means of which a multiphase fluid flow, in particular a charged with liquid droplets gas stream or a gas bubbles laden liquid stream, mixing by a substantially continuously expanding line piece while maintaining a uniform distribution of fluids can be promoted.

This object is achieved by the mixing element defined in claim 1. A mixing element for installation in a fluid-conducting means, which may be formed in particular as a housing or container shell, comprises an inlet opening for at least two components with a first cross-section, which is arranged in a plane which is substantially normal to the main flow direction in the inlet opening and an outlet opening for a mixture having a second cross-section, which is arranged in a plane which is substantially normal to the main flow direction in the outlet opening, wherein the mixing element has a cross-sectional profile which increases substantially continuously from the first cross section to the second cross section. In the mixing element, flow dividing layers are arranged such that a precise fitting of the mixing element into the substantially continuously expanding fluid conducting means is made possible. The mixing element is at least partially provided in the region between the inlet opening and the outlet opening. The precise fitting ensures that edge flows are deflected from the inner wall of the fluid-conducting means in the direction of the main flow and together with the main flow with at least approximately the same velocity distribution over the considered Flow cross-section are passed through the diffuser, as well as higher flow rate fluid as a compensating flow from a central region of the cross section in the direction of the wall region, thereby causing cross-mixing and thus improving the mixing of the fluid components. The stream-dividing layers comprise flow channels, which are in particular of a diffuser-like design, advantageously with flow channels that intersect openly, as shown, for example, in FIGS CH 547 120 be revealed. In such a mixing element, installation elements or layers are provided over at least part of the cross-section, by means of which the shear flow can be generated by intersecting flow paths, so that continuous turbulence arises when the flows are superimposed, whereby a continuous mixing of the mixture and a simultaneous flow in the direction of the mixer output can be achieved.

In an advantageous embodiment, a mixing element comprises at least two layers of a thin-walled material. In the simplest case, such a layer of flat, thin-walled sheets may be constructed, which are fitted in the widening cross-section of the fluid-conducting means such that the individual layers appear in each cross-section as mutually parallel cut surfaces, the distance of the cut surfaces of the layers but in the flow direction continuously increases. Such widening, flat layers are held in position by a framework of fasteners equipped with clamps or connectors. At least in the region of the inlet cross section, ie the inlet opening of the static mixer and in the region of the outlet cross section, ie the outlet opening of the static mixer, there is a possibility of attachment for each of the layers. The area spanned between two adjacent layers and the fluid conducting means, which is substantially normal to the main flow direction, therefore increases in a diffuser-like manner. The mixture flowing between the individual layers then flows essentially through a narrow channel, which widens in accordance with the cross-sectional increase of the mixer.

Such a layer may comprise a folded, unwound in a plane structure of a thin-walled plate material, wherein the fold may be formed in particular as ribs. A layer may comprise open channel-forming structures, in particular folded, wavy or jagged structures may be provided. Alternatively or in combination, closed channels forming structures, in particular honeycomb or tube-like structures can be used. In particular, at least one layer may comprise at least one flow channel. The structures are made of a metallic material, advantageously sheet metal and / or a steel and / or steel alloy can be used, which is not least dependent on the temperature, the pressure, and / or the nature of the flowing medium. High-temperature-resistant steels can also be used if it requires the temperature of the medium to be pumped. The production and mixing of corrosive mixtures requires the use of corrosion-resistant materials, in particular corrosion-resistant steels, but also ceramics, silicon compounds, carbon and / or coatings comprising PTFE, epoxy, halar, TNi alloys and / or carbide layers and / or galvanic coatings, especially by chromium plating or nickel plating applied coatings. If the mixture also contains solids, such as dust, high demands are placed on the scratch resistance of the internals of the mixing elements. With a scratch-resistant coating of the layers of the mixing element and / or the fluid-conducting agent, the service life of the static mixer is increased. In individual cases, the attachment of a dirt-repellent layer may be advantageous. For use in refrigeration or refrigeration systems, the static mixer is made of 304 L material and / or SS 316, and / or 904 L, and / or Duplex and / or 1.4878 low temperature, low distortion, corrosion resistant, as well as Characterize cold toughness. Plastics are used for static mixers which are not subject to high temperatures, in particular polypropylene, PVDF or polyethylene. A further application of a mixing element according to one of the claims can be provided in a static mixer in which a chemical reaction can take place. To carry out a chemical reaction, a rapid and uniform mixing of the fluid components to be brought into contact with one another is to be brought about become. For this purpose, it is possible to produce the flow-conducting layers either themselves from a catalyst material, or to the layers, which are preferably of an open-worked material, such as a sheet, or of a woven or knitted fabric or an at least partially porous material exist to apply a catalyst material. In a further example of application, a layer, which may be formed according to one of the preceding embodiments, comprises means for attaching microorganisms, in particular bacteria.

A static mixer is equipped according to a further embodiment with fluid-conducting means with partially planar lateral surfaces, in particular with rectangular or square cross-sectional areas which span trapezoidal lateral surfaces, which in their entirety result in the fluid-conducting agent. Such a static mixer includes at least one mixing element according to one of the preceding embodiments.

The dependent claims 2 to 8 relate to advantageous embodiments of the inventive mixing element. Uses of the inventive mixing element, in particular in a static mixer are each the subject of claims 9 and 10th

At least one layer of the mixing element comprises a surface-enlarging structure, in particular a flow channel. In the following text, a layer with a zig-zag profile is used to represent a layer with a surface-enlarging structure. Such Oberflächenvergrössernde structures include wavy profiles, ribbed profiles, profiles with projections of any geometry and / or angular position to the flow direction. A zig-zag profile consists of a series of edges when viewed with the cross-sectional area of the channel structure. Each of these edges forms a line in the three-dimensional position in the mixing element from the initial cross-section to the end cross-section. In the simplest case, the line is a straight line, but may have any, in particular periodically repeating, curve shape. Such a situation with edges with a curve shape can be used, for example, in a mixing element for a fluid-conducting medium with a change in the main flow direction, which leads to a change in direction of the flowing mixture in addition to the widening of the flow cross-section.

In a layer with a symmetrical profile, such as a zig-zag profile, two adjacent edges are adjacent to an open channel whose walls are formed by at least two planar and / or the curvature of the edges following profile surfaces. The channel has a V-shaped cross-section in this application example, since the lower boundary of the channel is also formed by an edge pointing in the opposite direction. In this embodiment, thus adjacent profile surfaces are arranged at an acute angle to each other, which is smaller than 180 °.

According to one exemplary embodiment, the edges of adjacent layers come to rest on one another in a line, so that two adjacent layers with edges facing in opposite directions come to lie on one another. Closed channels then form between the two adjacent layers, through which the flowing mixture is passed. According to this embodiment, the components of the mixture from the inlet opening into the mixer to the outlet opening remain in the same channel, which widens diffusely, corresponding to the expansion of the fluid-conducting means in the main flow direction. The distance between two adjacent layers increases from the cross section of the inlet opening to the cross section of the outlet opening, corresponding to the widening of the fluid-conducting means perpendicular to the main flow direction. Each layer can be produced from a flat plate material which is folded in such a way that the height of the edges and the distance between two adjacent edges increase in the direction of the widening, ie diffuser-like, mixing element. In this case, edges of adjacent layers come to rest on each other, so that a linear contact of adjacent layers takes place along the common edge. By this construction, a flow channel forms, the cross section of the inlet opening to the outlet opening continuously increases when the entire diffuser cross section is to be detected. The layers may consist of at least two planar and / or the curvature of the edges following profile surfaces be constructed and / or the profile surfaces themselves have an additional structuring, which are in particular formed as a wave or jagged ribs or fins and may include a series of open channels extending between the ribs or fins. Such structuring is described, for example, in US Pat CH 547 120 disclosed. It is also possible, according to a further embodiment, to combine layers having a profile surface with layers having surface-enlarging structures such that alternately a planar layer and a layer with surface-enlarging structures follow one another. This results in closed channels, which are bounded on the one hand by the flat position and on the other hand by the situation with the surface-enlarging structure.

In a mixing element according to a preferred embodiment, the flow channels of adjacent layers are openly crossing and / or diffuser-like. By this arrangement, a particularly rapid and good mixing of the components to be mixed is achieved. According to a further variant can be provided for better mixing that it does not come to a linear contact two adjacent layers with surface-enlarging structures, but touch the edges of the adjacent layers only punctiform. This punctiform contact is achieved in that two adjacent layers are arranged at an angle to each other. This causes the edge belonging to a first layer to have only a punctiform contact with a number of corresponding edges of the adjacent layer. The main advantage of this embodiment is due to the fact that the flowing medium does not always flow in the same channel as in the previously shown variants, but is always in a different channel at all times, ie continuously changes channels. In this case, the flowing medium is much more deflected than in the previous embodiments, resulting in an additional improvement of the mixing result. Alternatively, two adjacent layers can be combined with different profiles, which are also arranged to improve the mixing at an angle between 0 and 180 ° to each other.

According to a further embodiment, each layer forms a hollow body with surface-enlarging structures, is designed in particular with a ribbed, serrated or wavy surface. The edges of the surface-enlarging structures clamp demanch an interface, which is conceivable as a hollow body, which in particular has a conical shape. The Oberflächenvergrössernden structures are inclined at an angle of 0 to 180 ° to the flow direction. Several such hollow body can be inserted into each other. Advantageously, the angles of the surface-enlarging structures differ from two adjacent layers designed as hollow bodies, so that the flow can be deflected several times over the surface-enlarging structures.

A flow channel is delimited by at least two profile surfaces, wherein each two adjacent profile surfaces of a layer form a common edge. In particular flow channels with flat profile surfaces are inexpensive and easy to produce. Through the edges of a layer an interface is spanned, which is planar and / or at least partially conical. If a layer has multiple edges that jointly span such an interface, flat planar surfaces, for example, can easily be produced by flat profile surfaces, since the planar profile surfaces can be manufactured with close tolerances since the necessary dimensions are easily adjustable and verifiable. The shape of the interface acquires significance, in particular, when a multiplicity of layers arranged one above the other are required for producing a mixing element, in which the edges of adjacent layers touch at least pointwise.

In a mixing element, an interface is formed by the edges of a layer, which is flat and / or at least partially conical. The interface is the connecting surface of all edges. Most of the aforementioned embodiments for layers with surface-enlarging structures have planar boundary surfaces, so that adjacent layers each have one of these planar boundary surfaces in common. In a layer without surface-enlarging structure, the interface with the surface falls the situation together. According to a further embodiment, the interface may also represent an arbitrarily curved surface in space. In the case of a layer with a surface-enlarging structure, the edges of the surface-enlarging structures likewise span a surface curved in space. For a static mixer with a conical extension of the fluid-conducting means, the use of a layer with a conical interface is suitable so that the layers have boundary surfaces which are conically formed between the layers.

According to a preferred embodiment, the edges belonging to a layer of a mixing element are inclined relative to one another by an angle alpha in a range from 0 to 120 °, in particular from 60 to 90. Advantageously, intersecting edges of adjacent layers with the main flow direction opposite equal equal angle alpha / 2.

The cross section of the mixing element widens in particular conically from the first cross section to the second cross section, wherein in particular the diameter of the outlet cross section increases by a factor of 2 to 5 relative to the diameter of the inlet cross section, which equates to a cross sectional enlargement by a factor of 4 up to a factor of 25. In an advantageous embodiment, the mixing element widens conically from the first cross section to the second cross section, in particular the diameter of the inlet cross section widens by a factor of 2 to 5. Since the fluid conducting means in this embodiment widens conically, an abrupt transition from a cross section of a Supply line, which opens into the inlet opening, so usually a pipe to the cross section of the outlet opening, avoided. The outlet opening can be designed as an inlet opening in a heat exchanger or reactor. In this reactor, the mixture is already largely homogeneous. In particular, gaseous, liquid and / or solid components of the mixture are suspended. The mixing state is maintained by means of the mixing element (s) in a cone - which would otherwise contribute to the segregation as a diffuser. In most cases, even an improvement of the mixing of the components is achieved, in particular by means of Mixing elements with intersecting flow channels, so that the components are distributed homogeneously over each cross-section of the cone downstream of the inlet cross-section. The conical shape also offers considerable advantages for the installation of layers, since the conical shape of the fluid-conducting agent acts as a centering device for the installation of a conical mixing element. The fact that the mixing element is fitted in a conical fluid-conducting means, only a minimal amount of welding is required for installation. The mixing elements are advantageously designed in the manner of a diffuser, that is to say that the mixing elements adapt to the widening cross-section, ie in particular have a conical shape of their own. The fit is due to the conical shape of the mixing element by the positioning of the mixing elements or in the cone, whereby the position of the mixing element in the conical fluid-conducting means is clearly defined.

The layers should, if possible, directly adjacent to the fluid-conducting means, so the inner wall of the mixer. In the case of a line-shaped contact, the result is sectional curves of a flat layer or a layer having a surface-enlarging structure, in particular a surface-enlarging structure constructed from planar segments, such as a zig-zag profile, with conical inner wall conic sections, ie elliptical, depending on the inclination of the layer to the cone. parabolic or hyperbolic boundary lines. Each of the layers described above can be developed in one plane, therefore a processing can be generated by means of drawing programs from the desired position of the layer in the mixer. These developments contain not only the boundary lines of the situation but also the bending lines, so that an economical production of the layers is also possible in cases in which each angle is different, and therefore very complex bending operations are required.

A possible method for producing the mixer comprises the following steps: producing a fluid-conducting means having an inlet opening with a first cross-section and an outlet opening with a second cross-section, wherein the fluid-conducting means has a cross-sectional profile which increases continuously from the first cross section to the second cross section. In a further step, the mixing element is produced. The Mixing element comprises a plurality of layers, which are individually prefabricated and joined together by means of connecting means to a mixing element. If the surface structures of the layers can be unwound in one plane, the production is simplified, since the unwinding of each layer of planar plate-shaped base material can be cut by means of cutting means, and then foldable by means of bending means for producing the surface structure. This production is particularly suitable for layers of a metallic material. Layers of plastic are produced in their folded form in an extrusion process or by injection molding and subsequently cut to the shape that is required to form a flared, ie in particular conical mixing element. In a next step, the layers assembled into a mixing element are positioned in the mixer. When the mixing element is already fitted in a conical state in a conical fluid-conducting means, only a minimal amount of welding is necessary. In a conical mixer, the layers are centered by the cone, so that the assembly of the layers which have been folded out of the unwindments can also be carried out directly into the fluid-conducting means, since the positioning of the layers is effected by the conical shape of the fluid-conducting medium itself. the orientation of the layers is given to each other. Alternatively, the entire mixing element can also be produced by injection molding or in a lost form.

Using the structure of the layers corresponding to the cross-channel structure, it is possible that dead spaces arise because the position at the inlet cross-section flow paths through the angular orientation of the part of the layer adjacent to the inner wall are blocked. Therefore, after production, the channels on the side of the housing are checked and opened if necessary. The wall gap between the mixing elements and the inner wall of the housing is not more than 2% of the respective cross section, in particular not more than 1% of the respective cross section, particularly preferably not more than 0.5% of the respective cross section, so that a so-called "channeling effect" is demonstrably absent.

The wall gap to the fluid-conducting means should be smaller than the normal distance between two adjacent boundary surfaces, in particular as the height of a flow channel of a surface-enlarging structure. The height of the flow channel is defined as the normal distance between the two boundary surfaces, which are defined by the edges of the surface-enlarging structure. In particular, the wall gap should be at most half the height of the flow channel.

In the case of slight segregation in the area of the inlet opening, the liquid phase can be returned to the center via a so-called "riser plate" and distributed in the mixer over the cross section. A "riser plate" is defined as a built-in element, which is attached to the inside of the fluid-conducting means, in particular welded to the inside of the fluid-conducting means. This mounting element serves to return components that have accumulated at the lowest point of the fluid-conducting agent back into a mixing element. Built-in element should be representative of specific embodiments, such as a profile, a ramp, a plate or the like.

In addition to good distribution effect and / or mixing effect, only a small pressure loss is generated after each of the aforementioned solutions.

In an advantageous arrangement, mixing elements which are installed in a pipe section of constant cross-section and mixing elements according to one of the preceding embodiments can be combined with one another. To achieve an improved mixing effect is a conventional mixing element in a pipe section before entering the static mixer with a fluid conducting means with widening cross-section. According to each of the preceding embodiments, two adjacent mixing elements can be arranged rotated at an angle between 0 and 90 °, in particular between 60 and 90 °. As a result of the rotation, a further deflection of the flow can be achieved, which has proved to be advantageous, in particular for the exemplary embodiments mentioned, with at least section-wise channel flow.

The arrangement of a mixing element can take place upstream of a heat exchanger, in particular in the inlet region of a heat exchanger. With the expanding mixing element, the flow is evenly distributed in the flow direction at increasing the average cross section to the expanded cross section, and ensures a homogeneity of the flow over the entire cross section.

The use of the mixing element takes place in a method for denitrification of exhaust gases, for the distribution of exhaust gases on a catalyst surface, in a method for producing LNG (liquid natural gas), in particular for introducing a gas-liquid mixture such as a coolant for LNG gas processing in one heat exchange device. The heat exchange device may in particular comprise a heat exchanger, advantageously a shell-and-tube heat exchanger.

For denitrification of exhaust gases, liquid urea is vaporized and mixed with the gas stream. Both the evaporation and the mixture can be done simultaneously in the static mixer. Due to the combined process management, there is a need to supply the urea gas mixture for further processing to the subsequent process step already in the mixed state. Another application is to evaporate liquids in a static mixer with widening cross section and mix at the same time. In particular, in systems with limited space, the use of such a mixer is advantageous to obtain a mixture when expanded to larger diameter in a mixed state.

In natural gas processing, coolant must be cooled for further use. The coolant consists of various gaseous and liquid components, the largest being methane and ethane. The mixture of gaseous and liquid coolant is usually passed in a pipeline to a heat exchanger, in particular a shell and tube heat exchanger, where it is then cooled by a multi-pass system. The entrance of the shell and tube heat exchanger usually has a size DN1500 to DN2400 (1.5 to 2.4 m), which means that the mixture in the pipeline of essentially DN600 (0.6 m) must be expanded via a cone into the inlet of the shell and tube heat exchanger. In order for the heat exchanger to reach its full capacity, the gaseous and liquid components must be uniformly mixed over the cross section and fed in equal proportions to the individual tubes. The heat exchanger is designed essentially for gas-liquid mixtures, that is, the gas-liquid mixture should have a uniform over the inlet cross section in the heat exchanger distribution.

Another possible application of the mixing element in vehicle construction relates to the entry of an engine exhaust gas into a catalytic converter for the catalytic separation of pollutants, in particular nitrogen oxides (NOx) and their binding by catalytic reaction on the catalyst surface. Since in vehicles, especially in trucks, the space required for a static mixer in an exhaust is relatively small, static mixers with the above-described expanding cross section for such purposes are of great advantage, since no additional space is needed. Even with an exhaust system in which the exhaust gases from a relatively small exhaust pipe into a larger catalyst housing open, the problem of segregation of exhaust gas and liquid and / or solid components occurs. Thus, the catalyst is not unilaterally worn, a complete evaporation and at the same time a good homogenization is necessary, which can be achieved with a static mixer according to one of the above embodiments at low pressure drops.

Another possible use of the mixing element according to one of the preceding embodiments consists in the chemical reaction technique for carrying out catalytic and / or biogenic reactions, in particular in widening cross sections for the entry of a single- or multi-phase fluid mixture in a reactor. Gaseous and liquid components often have to be dispersed in front of a reactor. After generation of the bubble bed and the uniform distribution of the components, the current is often widened, because the current with a diameter larger than the diameter diameter in a Reactor containing a catalyst occurs. The static mixer is used to maintain the homogeneity of the mixture. The lower Abbremseffekt static mixer in comparison to an abrupt cross-sectional transition of supply line to the inlet cross section in the reactor vessel helps to make the bubbles coalesce less rapidly.

Another use of the static mixer is in the field of gas liquefaction. In gas liquefaction, various gas streams are mixed and then fed into a multi-pipe system. In an intended application, the gas is mixed in a DN 600 (0.6 m) pipe and then evenly distributed over the various pipes in a housing diameter DN 12000 (12 m). At the time of the application known prior art baffles are used for this purpose. So that each tube receives the same proportion of gas, the use of a static mixer according to one of the preceding embodiments lends itself.

Another field of application for the static mixer is in the field of reactors in which a piston flow is to be maintained, so-called plug-flow reactors. In plug-flow reactors, mixing elements are used to direct the fluid in a piston flow through a cylindrical housing. If the diameter needs to be changed, the piston flow in the conical section will be disturbed due to the lack of mixing elements. With the use of conical mixing elements, the flow properties can be maintained in the conical section.

As mentioned above, a static mixer of the above-mentioned design can also be combined with a static mixer operating as a premixer with a constant, in particular hollow cylindrical, cross-sectional profile. The mixing of the individual fluid components takes place in the static mixer cylindrical design, the static mixer with expanding cross-section has primarily the function of uniformly expand the mixture and / or distribute.

In order to reduce pressure losses, it is also possible to provide distances between individual mixing elements, in which flow conditions prevail, such as in a pipeline. Short distances between the individual conical mixing elements do not cause remarkable segregation, but serve to redistribute the flow without additional pressure loss.

Fig. 1

zeigt ein erstes Ausführungsbeispiel eines Mischelements aus ebenen Lagen

Fig. 2

zeigt ein zweites Ausführungsbeispiel eines Mischelements aus Lagen mit Zick-Zack Profil

Fig. 3

zeigt ein drittes Ausführungsbeispiel eines Mischelements aus einer Kombination aus ebenen Lagen mit Lagen mit Zick-Zack Profil

Fig. 4a

zeigt den Einbau von Lagen mit Zick-Zackprofil in konisches Mischergehäuse

Fig. 4b

zeigt den Schnitt durch eine Serie von Lagen mit Zick-Zackprofil

Fig. 4c

zeigt zwei sich kreuzende Lagen mit Zick-Zack Profil

Fig. 5a

zeigt eine erste Lage mit einem Zick-Zackprofil, welches einen konischen Hohlkörper ausbildet

Fig. 5b

zeigt eine zweite Lage mit einem Zick-Zackprofil, welches einen konischen Hohlkörper ausbildet

Fig. 6a

zeigt den Einbau einer Lage mit Zick-Zack Profil aus Fig. 6a in ein konisches Mischergehäuse

Fig. 6b

zeigt eine relativ zur Strömungshauptrichtung geneigte Randlage mit Zick-Zack Profil

Fig. 7

zeigt eine Anordnung von zwei Mischelementen für einen konischen Statikmischer

Fig. 8a

zeigt ein fluidleitendes Mittel mit quadratischem Querschnitt

Fig. 8b

zeigt ein fluidleitendes Mittel mit rechteckigem Querschnitt

Fig. 8c

zeigt zwei benachbarte Lagen eines Mischelements mit sich offen kreuzenden Strömungskanälen

The invention will be explained with reference to the drawings. Show it:

Fig. 1

shows a first embodiment of a mixing element of flat layers

Fig. 2

shows a second embodiment of a mixing element of layers with zig-zag profile

Fig. 3

shows a third embodiment of a mixing element of a combination of flat layers with layers with zig-zag profile

Fig. 4a

shows the installation of layers with zigzag profile in conical mixer housing

Fig. 4b

shows the section through a series of layers with zigzag profile

Fig. 4c

shows two intersecting layers with zig-zag profile

Fig. 5a

shows a first layer with a zig-zag profile, which forms a conical hollow body

Fig. 5b

shows a second layer with a zig-zag profile, which forms a conical hollow body

Fig. 6a

shows the installation of a layer with zig-zag profile of Fig. 6a in a conical mixer housing

Fig. 6b

shows a tilted relative to the main flow direction edge layer zig-zag profile

Fig. 7

shows an arrangement of two mixing elements for a conical static mixer

Fig. 8a

shows a fluid conducting means with square cross-section

Fig. 8b

shows a fluid conducting means with rectangular cross-section

Fig. 8c

shows two adjacent layers of a mixing element with open-crossing flow channels

In Fig. 1, a first embodiment of a mixing element is shown. The fluid-conducting means or housing 1 has a substantially conical shape and is indicated in Fig. 1 only. Each of the layers is shown in the illustrated embodiment with a flat surface, but any Oberflächenvergrössernde structures can be provided according to at least one of the aforementioned embodiments on at least some of the layers shown. In the illustrated configuration, a flow of a fluid mixture is directed into the region between the layers from the inlet section 9 to the outlet section 10, arrow 11 indicating the main flow direction. By fluid mixture is meant in particular a gas-liquid mixture or a mixture of gases or a mixture of liquids. Each of the phases may additionally contain a solids content. The flow is uniformly expanded and distributed by the alignment of the layers 2 adapted to the shape of the fluid-conducting means. The number and spacing of the layers depend essentially on the mixing effect in each layer. This in turn is influenced by the flow rate, and not least by the properties of the flowing components, in particular their density or viscosity. At each of the walls of the layers and the housing can cause frictional effects, so that the edge flows arise, resulting in a lower throughput in edge and wall areas, because the near wall flow through the friction effects has a lower speed than the main flow. In the example shown, the layers 2 by holding devices 7, 8 at intervals held together. According to another, not shown embodiment, the layers can also be attached to the inner wall of the fluid-conducting agent itself by means of plug or clamp connections. The assembly of layers into a conically configured fluid-conducting means can be carried out in such a way that the layers are pre-assembled with the holding devices, in order then to be inserted as a prefabricated mixing element 12 into the housing. The conical shape of the housing 1 thus also causes the centering of such a prefabricated mixing element 12th

In Fig. 2 shows a second embodiment with a mixing element of layers with zig-zag profile shown. For the sake of clarity, only two such layers (3, 4) are shown in FIG. The flowing mixture is passed through the layers that form V-shaped flow channels. In the illustrated case, the layer 3 is supported along the common edges 15 on the layer 4. An edge 15 is part of the layer 4 and has normal to the main flow direction, represented by arrow 11 in the direction of the fluid-conducting means shown in the figure as the upper housing wall. An edge 15 belongs to the layer 3 and is in line contact with the edge 15 of the layer 4. The profile surfaces (13, 14) of the zig-zag profile forming the respective layer converge at the edges, forming a flow channel through which the components to be mixed flow. The flow channel is thus limited by the profile surfaces (13,14). If the edges of adjacent layers over the entire length between inlet cross-section 9 and outlet cross-section 10 touch, closed flow channels are formed by adjacent layers, which are each constructed of two open flow channels (5, 6). Such a closed flow channel has a substantially diamond-shaped cross-section. For reasons of simplified assembly or improved mixing of the individual partial flows, it is possible to provide a distance between the layers (3, 4), in an analogous manner, as shown in Fig. 1. The edges 15 of the two adjacent, superimposed layers then no longer touch, so that no common edge 15 is formed more. From the profile surfaces (13,14) then an open flow channel is formed.

The attachment of the layers (3,4) and other, not shown, layers in Fig. 2 for forming a mixing element can by means of the same fastening means, as shown in Fig. 1, take place, with the possibility of a welded joint, in particular a Spot welding, and / or provide a solder joint and / or an adhesive bond or the like.

Additional possibilities of the flow deflection and the improvement of the mixing result by the channels are provided with not shown flow-deflecting means. In particular, perforated plates, projections in the channel walls, tabs or inserted into the flow channels, bulk-like distributed, oberfächenvergrössernde structures are provided. Such structures are used in gas-liquid absorption and as column internals, especially Raschig rings, Berl saddles, Intalox saddles, Pall rings, Tellerette structures. Another possibility is to provide the layer itself with flow-deflecting structures, in particular with a structure that is comparable to an expanded metal, as well as with one of the structures that have already been mentioned in the general description of the mixing element.

A third embodiment according to FIG. 3 comprises a mixing element made of a combination of planar layers 2 with layers with profile surfaces (13, 14), in particular with a zig-zag profile. The presentation of further layers has been omitted for clarity. Instead of the flat layer 2, a layer with profile surfaces is used, which differ from Profilfächen with zig-zag profile. Through the layer 4, and the two layers 2 closed flow channels are formed. The edge 15 of the layer 4 touches the layer 2, but not the edge 15 of the layer 3. The flow channels thus have a substantially triangular cross-section. By analogy with the expanding cross section of the mixing element, the cross section of the flow channels formed by the adjacent layers (2, 3, 4) increases continuously in the main flow direction. The advantage of a mixing element with layers which form flow channels lies in their low pressure loss and their contribution to the generation and / or maintenance of a homogeneous mixture in a simpler constructive Design. The flowing medium must follow the course of the flow path defined by the fluid-conducting means, therefore the composition of the flowing mixture remains constant in accordance with the continuity theorem through the flow channel as long as no chemical reaction takes place in the static mixer. The flow is only for a short time in the fluid-conducting means, since the fluid-conducting means usually serves only as a transition from a first cross section of smaller diameter to a second cross section of larger diameter. The distance is therefore too short for appreciable demixing effects along the flow channels to be noticeable in the flow through the fluid-conducting means. In the outlet section 10, which generally coincides with one end of a flow channel, all partial flows are brought together.

At high flow velocities, at the ends of the flow channels of the layers which lie in the plane of the outlet cross-section 10, detachment of vortices according to the principle of the Karman vortex street may occur, whereby the thorough mixing can even be improved.

According to a further advantageous exemplary embodiment according to FIG. 4 a, for better mixing it can be provided that there is no linear contact of two adjacent edges 15 according to FIG. 2 or one of the edges 15 with the layer 2 according to FIG. 3 arranged therebetween, but two intersecting adjacent layers (3, 4) are provided with zig-zag profile, as shown by way of example in Fig. 4c, in which the edges 15 touch only in one point. This punctiform contact takes place for the edges 15 in the contact point 17 is achieved in that two adjacent layers (3,4) are arranged at an angle to each other. This causes that the edge 15, which belongs to a first layer 3, has only one point of contact 17 with the edge 15 of the layer 4. The angle alpha between two edges 15 of adjacent layers is between 0 and 120 °, in particular between 60 and 90 °. In a particularly advantageous embodiment, an edge 15 of the layer 3 is alpha / 2 to one side, an edge of the adjacent layer 4 by alpha / 2 to the other side with respect to the main flow direction inclined. This arrangement yields the later-mentioned "cross-channel structure" as they CH 547 120 is described. The edges of the layer 3 span in the embodiment of Fig. 4a, 4b or 4c on a plane which is referred to as the interface 16 of the layer. The interface contains all points of contact of adjacent layers when adjacent layers are arranged to form a common interface. The main advantage of this arrangement, which is also referred to as a cross-channel structure according to this exemplary embodiment, is that the flowing mixture does not always flow in the same flow channel, as in the previously described variants, but is in a different flow channel at all times, ie continuously the flow channel replaced. In this case, the flowing mixture is much more deflected than in the previous embodiments, which has an additional improvement of the mixing result. In Fig. 4a, the fitting of layers (3, 4) is shown with zig-zag profile and flat boundary surfaces, with only every other layer 3 is shown, while the adjacent layers 4 have been omitted for clarity of illustration. The layers are configured such that the shortest possible distance from two adjacent edges, measured continuously in a cross section normal to the main flow direction, continuously increases from the inlet cross section 9 to the outlet cross section 10. Equally, it is possible that the normal distance between two adjacent boundary surfaces 16 as measured in a cross section normal to the main flow direction from the inlet cross section 9 to the outlet cross section 10 continuously increases or is kept constant, whereby the boundary surfaces of the layers come to lie parallel to each other. According to the exemplary embodiment illustrated in FIG. 4a, adjacent boundary surfaces are widened in a diffuser-like manner from the inlet cross-section 9 to the outlet cross-section 10.

At least some of these points of contact 17 may be formed as welding points to join together adjacent layers (3, 4) to form a mixing element.

According to a further variant, the boundary surfaces 16 of adjacent edges (3, 4) do not coincide, but are at a small distance from one another, so that adjacent layers do not touch one another. Through this As a result, a portion of the flowing mixture is not completely redirected, so that the flow is slowed down less. The effects on the mixing depend on the components to be mixed, the proportion of the different phases and the tendency for segregation. By changing the distance of the layers from each other, the pressure loss of the static mixer is also affected.

The layers should, if possible, directly adjoin the inner wall of the fluid-conducting agent, as indicated in FIG. 4a, so that at most a small distance between layer 3 and inner wall remains. In the case of a linear contact of the layer 3, there are conical sections as a sectional curve of a flat or arbitrarily folded layer of flat segments with a conical inner wall, ie elliptical, parabolic or hyperbolic boundary lines depending on the inclination of the layer to the inner wall, as shown in FIG. 5a and FIG 5b. Each of the layers described above, one of which is shown in Fig. 5a, is developable in a plane, therefore, by means of drawing programs from the desired position of the situation in the mixer, a settlement can be generated. These developments contain not only the boundary lines of the situation but also the bending lines, so that an economical production of the layers is also possible in cases in which each angle is different, and therefore very complex bending operations are required. FIG. 5 a shows a cross section through such a cross channel structure, whereby only every second layer 3 is shown, as in FIG. 4 a. Using the structure of the layers corresponding to the cross-channel structure, it is possible that dead spaces arise because the location at the inlet cross-section 10 flow paths are blocked by the angular orientation of the part of the layer adjacent to the inner wall. Therefore, after assembling the layers to a mixing element, the channels on the housing side, that is the inner wall, are checked and opened if necessary. The wall gap between mixing elements and the inner wall of the fluid-conducting means 1 is smaller than the normal distance between two adjacent boundary surfaces 16, in particular smaller than the height of a flow channel (5, 6) of a surface-enlarging structure, in particular of the illustrated zig-zag profile, so that a so-called " Channeling effect "demonstrably fails.

In Fig. 5b, a layer 3 is shown in the edge region of the mixing element. The layer 3 has sectional curves 18, which adjoin the inner wall of the fluid-conducting agent. Would the profile surfaces (13,14) of the layers directly adjacent to the inner wall, flow channel 5 would not flow through. Therefore, these profile surfaces are at least partially arranged at a distance from the inner wall, or opened after assembly of the mixing element for the flow.

According to a further embodiment according to FIGS. 6a and 6b, each layer forms a hollow body 19 with surface-enlarging structures. The surface-enlarging structure of the hollow body 19, in particular the ribs, serrations or waves, are inclined at an angle of 0 to 180 ° relative to the main flow direction. Several such hollow bodies can be designed such that they can be inserted into one another. In the present case, hollow body 19 can be completely integrated into hollow body 20 by inserting hollow body 19 into hollow body 20. In the illustrated embodiment, hollow bodies (19, 20) have a zig-zag profile. The outward as well as the inwardly directed edges each span an interface which is conically shaped. Has hollow body 19 relative to the hollow body 20 on an excess, which means nothing else than that the inner interface of hollow body 20 comes to lie within the outer boundary surface of the hollow body 19, wedged the two hollow body (19,20) during installation such that in the case of not too great forces by the flowing medium on the hollow body in the installed state of the mixing element to an additional fixation of the hollow body, such as by welding points or fastening devices, can be completely dispensed with. The clamping forces provide sufficient security against a change in position of the layers during operation. If it is possible from the installation site, such a mixing element can be installed in a fluid-conducting means, which has a substantially vertically arranged main flow axis, so that the mixture flows through the static mixer from bottom to top. Should there be a risk that layers are moved against each other or even entrained with the flow through the outlet cross-section, because they are made of a lightweight material, such as light metal or plastic optionally, a retaining device may be provided in the region of the outlet cross-section 11.

Fig. 7 shows two mixing elements 12 for a conical static mixer, which are arranged directly adjacent to each other. These mixing elements are constructed of layers 3, which in particular have a zig-zag profile according to one of the preceding embodiments, wherein adjacent layers are inclined relative to one another by an angle different from 0 °. Each mixing element 12 has high stability because the layers are supported against each other and against the inner wall of the fluid-conducting agent. The main flow direction is represented by the arrow 11.

According to another variant, not shown, the two mixing elements 12 may also be arranged at a distance from each other.

FIG. 8 a shows a fluid-conducting medium with a square cross-section. From the inlet cross-section 9, the cross-sectional area increases continuously to the outlet cross-section 10. Each side of the square increases continuously.

Fig. 8b shows a fluid conducting means of rectangular cross section. From the inlet cross-section 9, the cross-sectional area increases continuously to the outlet cross-section 10. In this case, only every second side length of the rectangular cross-section continuously increases, in FIG. 8b is the side length 21. In Fig. 8b, the boundary surfaces 16 of the layers of the mixing element are indicated.

Fig. 8c shows the arrangement of two adjacent layers (3,4) with zig-zag profile for one of the embodiments shown in Fig. 8a or Fig. 8b. Other layers are indicated only by their interfaces 16, not to overload the Fig. 8c. In this variant, no special processing steps are required for the execution of the adjoining the inner wall of the fluid-conducting means 1 peripheral layers, so that the production cost for a mixing element with a fluid-conducting means 1 with sections flat lateral surfaces is lower. With regard to the possibilities of expanding the channels of the individual layers from the inlet cross-section 9 to Exit cross-section 10 is referred to the possibilities shown in Fig. 4a to Fig. 4c for zig-zag profiles, which are again exemplary of all other, mentioned in the text versions of the layers.

LIST OF REFERENCE NUMBERS

1.

Fluid conducting agent

Second

location

Third

location

4th

location

5th

flow channel

6th

flow channel

7th

holder

8th.

holder

9th

Inlet cross-section

10th

Outlet cross section

11th

arrow

12th

mixing element

13th

profile surface

14th

profile surface

15th

edge

16th

interface

17th

point of contact

18th

section curve

19th

hollow body

20th

hollow body

21st

page length

Claims (13)

Mixing element (12) for installation in a fluid-conducting means (1) comprising an inlet opening (9) for at least two components with a first cross section, which is arranged in a plane which is substantially normal to the main flow direction (11) in the inlet opening (9 ), and an outlet opening (10) for a mixture having a second cross-section, which is arranged in a plane which is substantially normal to the main flow direction (11) in the outlet opening (10), wherein the mixing element (12) has a cross-sectional profile which increases substantially continuously from the first cross-section to the second cross-section, characterized in that in the mixing element stream-dividing layers (2,3,4) are arranged such that a precise fitting of the mixing element (12) in the substantially continuously expanding fluid-conducting medium (1) is enabled. Mixing element according to claim 1, wherein at least one layer (3,4) comprises at least one flow channel (5,6). Mixing element according to claims 1 or 2, wherein flow channels (5, 6) of adjacent layers (3, 4) are openly crossing and / or of diffuser-like design. Mixing element according to one of the preceding claims, wherein a flow channel of at least two profile surfaces (13,14) is limited, wherein each two adjacent profile surfaces of a layer (3,4) form a common edge (15). Mixing element according to one of the preceding claims, wherein by the edges (15) of a layer (3,4) an interface (16) is clamped, which is flat and / or at least partially conical. Mixing element according to one of the preceding claims, wherein the edges (15) belonging to one layer are inclined relative to one another by an angle alpha of a range from 0 to 120 °, in particular from 60 to 90 °, in particular intersecting edges of adjacent layers (15). 3,4) with the main flow direction opposite equal equal angle alpha / 2 enclose. Mixing element according to one of the preceding claims, wherein the cross section of the mixing element from the first cross section to the second cross section in particular flared, in particular the diameter of the outlet cross section increases relative to the diameter of the inlet cross section by a factor of 2 to 5. Mixing element according to one of the preceding claims, wherein a wall gap to the fluid-conducting means (1) smaller than the normal distance between two adjacent boundary surfaces (16), in particular smaller than the height of a flow channel (5,6) is formed of a surface-enlarging structure. Arrangement with a conventional mixing element and at least one conical mixing element according to one of the preceding claims, wherein in particular adjacent mixing elements are arranged rotated by 0 to 90 °, preferably by 60 to 90 ° from each other. Arrangement according to claim 9, wherein the mixing elements are arranged in a fluid-conducting element (1) in the inlet region of a heat exchanger. Use of a mixing element according to one of the preceding claims in a method for natural gas processing and / or for denitrification of exhaust gas. Use of a mixing element for carrying out catalytic and / or biogenic reactions. Static mixer with at least one mixing element according to one of the preceding claims.

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