Device for carrying out mechanical, chemical and / or thermal processes in a product

Abstract

Device for carrying out mechanical, chemical and / or thermal processes in a product located in a housing with mixing and cleaning elements and transport elements on at least one shaft (11) acting on the product, wherein kneading wings (6, 6.1, 6.2) are mounted on disc elements (10) and interact with a kneading counter-hook (1, 1.1) projecting into the interior of the housing towards the shaft (11), characterized in that an edge (12.3, 12.4) of the kneading counter-hook (1, 1.1) is formed with a pointed or blunt end face (17), to which a surface (14) adjoins after a chamfer (13), and interacts with the kneading wings (6.1, 6.2), wherein the edge edges (12.2.1, 12.2.2) of the kneading wings are also formed with a pointed end face and a corresponding chamfer and are parallel to the surface. (14) along the kneading counter-hook (1, 1.1).

Description

The invention relates to an apparatus for performing mechanical, chemical and / or thermal processes in a product according to the preamble of claim 1.Prior ArtSuch apparatuses are also referred to as mixing kneaders. They serve a wide variety of purposes. First, solvent recovery evaporation is mentioned, which is batch or continuous and often also under vacuum. As a result, for example, distillation residues and, in particular, toluene diisocyanates are treated, but also production residues with toxic or high-boiling solvents from chemical and pharmaceutical production, washing solutions and paint sludges, polymer solutions, elastomer solutions from solvent polymerization, adhesives and sealants.The apparatuses are also used to carry out continuous or batchwise contact drying of water- and / or solvent-moist products, often likewise under vacuum. The application is intended above all for pigments, dyes, fine chemicals, additives, such as salts, oxides, hydroxides, antioxidants, temperature-sensitive pharmaceutical and vitamin products, active ingredients, polymers, synthetic rubbers, polymer suspensions, latex, hydrogels, waxes, pesticides and residues from chemical or pharmaceutical production, such as salts, catalysts, slags, waste liquors. These processes are also used in food production, for example in the production and / or treatment of block milk, sugar substitutes, starch derivatives, alginates, for the treatment of industrial sludges, oil sludges, bioslurrases, paper sludges, lacquer sludges and generally for the treatment of tacky, crusting, tough-paste products, waste products and cellulose derivatives.In a mixing kneader, a polycondensation reaction can take place, usually continuously and usually in the melt, and is used above all in the treatment of polyamides, polyesters, polyacetates, polyimides, thermoplastics, elastomers, silicones, urea resins, phenolic resins, detergents and fertilisers. For example, it is used on polymer melts after bulk polymerization to methacrylic acid derivatives.A polymerization reaction can also take place, likewise usually continuously. This is applied to polyacrylates, hydrogels, polyols, thermoplastic polymers, elastomers, syndiotactic polystyrene and polyacrylamides.Degassing and / or devolatilization can take place in mixing kneaders. This is applied to polymer melts, after (co)polymerization of monomer(s), after condensation of polyester or polyamide melts, to spinning solutions for synthetic fibers and to polymer or elastomer granules or powders in the solid state.In general, solid, liquid or multi-phase reactions can take place in the mixing kneader. This applies in particular to baking reactions in the treatment of hydrofluoric acid, stearates, cyanides, polyphosphates, cyanuric acids, cellulose derivatives, esters, ethers, polyacetal resins, sulfanilic acids, Cu phthalocyanines, starch derivatives, ammonium polyphosphates, sulfonates, pesticides and fertilisers.Furthermore, reactions can take place in solid / gaseous form (e.g. carboxylation) or in liquid / gaseous form. This is used in the treatment of acetates, acids, Kolbe-Schmitt reactions, e.g. BON, Na salicylates, parahydroxibenzoates and pharmaceutical products.Liquid / liquid reactions take place in neutralization reactions and transesterification reactions.Dissolving and / or degassing in such mixing kneaders takes place in spinning solutions for synthetic fibers, polyamides, polyesters and celluloses.Flushing takes place in the treatment or production of pigments.Solid-state postcondensation takes place in the production or treatment of polyesters, polycarbonates and polyamides, continuous mashing, for example in the treatment of fibers, for example cellulose fibers with solvents, crystallization from the melt or from solutions in the treatment of salts, fine chemicals, polyols, alcoholates, compounding, mixing (continuous and / or batch-wise) in the case of polymer mixtures, silicone compositions, sealants, fly ash, coagulation (in particular continuous) in the treatment of polymer suspensions.In a mixing kneader, multifunctional processes can also be combined, for example heating, drying, melting, crystallizing, mixing, degassing, reacting, all continuously or batchwise. Polymers, elastomers, inorganic products, residues, pharmaceutical products, food products, printing inks are thereby produced or treated.In mixing kneaders, vacuum sublimation / desublimation can also take place, as a result of which chemical precursors, for example anthraquinone, metal chlorides, ferrocenes, iodine, organometallic compounds etc., are purified. Furthermore, pharmaceutical intermediates can be prepared.Continuous carrier gas desublimation takes place, for example, in the case of organic intermediates, for example anthraquinone and fine chemicals.In essence, a distinction is made between single-shaft and two-shaft mixing kneaders. A single-shaft mixing kneader is known, for example, from AT 334 328 B, CH 658 798 A5 or CH 686 406 A5. In this case, an axially running shaft which is occupied by disk elements and rotates about an axis of rotation in a direction of rotation is arranged in a housing. This causes the transport of the product in the transport direction. Between the disc elements counter elements are fixedly mounted on the housing. The disk elements are arranged in planes perpendicular to the kneader shaft and form between them free sectors which form kneading spaces with the planes of adjacent disk elements.A multiple shaft mixing and kneading machine is described in CH 506 322 A. There are radial disk elements on a shaft and axially aligned kneading blades arranged between the disks. Between these discs engage mixing and kneading elements shaped like frames from the other shaft. These mixing and kneading elements clean the discs and kneading blades of the first shaft. The kneading blades on both shafts again clean the inner wall of the housing.These known twin-shaft mixing kneaders have the disadvantage that, owing to the eight-shaped housing cross section, they have a weak point in the region of the connection of the two shaft housings. In this area, when processing tough products and / or processes which proceed under pressure, high stresses arise, which can only be controlled by complicated structural measures.A mixing kneader of the above-mentioned type is known, for example, from EP 0 517 068 B1. In the mixer housing, two shafts running axially parallel rotate either in opposite directions or in the same direction. In this case, mixing bars placed on disk elements act with one another. In addition to the function of mixing, the mixing bars have the task of cleaning surfaces of the mixer housing, the shafts and the disk elements which are in contact with the product as well as possible and thus avoiding intermixed zones. In particular in the case of highly compacting, curing and crusting products, the edge mobility of the mixing bars leads to high local mechanical loads on the mixing bars and the shafts. These force peaks occur in particular when the mixing bars engage in those zones where the product is difficult to yield. Such zones are given, for example, where the disk elements are placed on the shaft.Furthermore, from DE 199 40 521 A1 a mixing kneader from the above-mentioned is known. This is known in which the support elements form a recess in the area of the kneading blades so that the kneading blade extends axially as much as possible. Such a mixing kneader has excellent self-cleaning of all product-contacted surfaces of the casing and shafts, but has a property that the supporting members of the kneading blades require recesses due to the paths of the kneading blades, resulting in complicated supporting member shapes. This results on the one hand in a complicated production method and on the other hand in local stress peaks on the shaft and the support elements in the event of mechanical stress. These stress peaks, which occur mainly in the sharp-edged recesses and changes in thickness, in particular in the region where the supporting elements are welded onto the shaft core, are triggers for cracks in the shaft and the supporting elements due to material fatigue.DE 10 2008 048 580 A1 discloses a mixing kneader of the type claimed, but without a kneading counterhook. The shafts running parallel to one another are fitted with disc elements, at the end of which there is a kneading blade. These kneading blades also cooperate to treat the product because they mesh with each other. However, only the lateral blades cooperate with the respectively adjacent kneading blade.DE 37 04 269 A1 shows both kneading counter-hooks and kneading blades. The kneading blades are designed as bars without lateral blades. They have only a pointed edge at the front, which is exclusively intended for scraping the inner wall of the housing.U.S. Pat. No. 5,230,562 A further discloses a device in which two shafts are arranged in a housing. On these shafts there are disc elements, two disc elements being connected to each other by a scraper rod. The disk elements are at least partially beveled on their circumference.The closest prior art is considered to be DE 101 20 391 A1. It does not show a kneading counter hook, but kneading blades which mesh with one another. FIG. 4 describes a kneading blade whose edge is designed as a scraping edge, which is followed counter to the direction of movement of the mixing element or toward the rear by a surface which encloses a clearance angle with respect to, for example, a disk surface to be swept.The object is to provide a method for performing a processThe object of the present invention is to control the action of the mixing elements and cleaning elements and transport elements in such a way that they adapt specifically to the product and its requirements.SolutionTo achieve this object, the features of the characterizing part of claim 1 lead.It has been found that with this marginal edge, the configuration of the marginal edge and the cooperation of marginal edges of two elements, the action of a mixing kneader and the effect on the product can be determined quite substantially. In principle, the elements determine whether a product is transported from an inlet to an outlet at all and / or is optionally mixed back. They determine the residence time of the product in the mixing kneader. They determine the heat input into the product and they determine how intensively a product is mixed and / or sheared. This results in numerous interactions between the individual interacting elements, which in total have an express effect on the quality of the product.They also determine the cleaning of the remaining parts of the mixing kneader, in particular of the shaft and the inner wall of the housing, but also of the disk elements and the elements themselves. This in turn prevents product encrustations, which in turn can have a negative effect on the quality of the product.Depending on the configuration of the edge, product accumulations and consequently increased local load peaks are also avoided. They contribute to avoiding product back-up and consequently to avoiding the risk of products pushing up into existing stubs (metering stubs, vapor outlet, inspection glass stubs or stubs in general). They also contribute to improving "product sag" on static elements.In a preferred exemplary embodiment of the invention, the marginal edge is formed so as to taper to a point. This means that it cuts into the product, but that it can also more easily scrape off product encrustations at the same time. It is conceivable here for the marginal edges to be formed with an inclination in a specific direction. This inclination in any case causes the product to be guided along the inclination, i.e. it is subjected to a transport action.In another embodiment, the marginal edge is wedge-shaped so that it divides the product into two partial streams. In this case, the transport effect is relatively neutral in the case of an isosceles wedge.Thus, the geometric shape of the marginal edge can be designed such that the product transport can be influenced selectively axially to the left, to the right or in a neutral manner with respect to the conveying.The marginal edge itself can be sharply intersecting or blunt if necessary. The blunt shape then serves to increase the torque in processes where increased need for mechanical kneading energy or for splitting product agglomerates or product tubers is required.A disturbing angle of the current when rotating elements strike a stationary element or also when rotating elements strike each other can be formed selectively positively or negatively. Positive means that the angle opens and thus a clearance angle is produced, negative means that the angle closes and thus a clamping angle is produced. In a preferred embodiment, it can also be conceivable for the respective cooperating marginal edges to be arranged on both sides of the elements, so that it is possible to reverse the direction of rotation of the shaft / s without the effect of the elements cooperating with one another being impaired.DESCRIPTION OF THE FIGURESFurther advantages, features and details of the invention will become apparent from the following description of preferred exemplary embodiments and from the drawing, in which FIG. 1 is a perspective view of a kneading counter hook according to the invention; FIG. 2 is a schematic front view of a disk element on a shaft with a kneading blade arranged on the disk element; FIG. 3 shows a schematic illustration of the interaction of kneading vanes with kneading counter-hooks; FIG. 4 shows a schematic illustration of a further exemplary embodiment of a kneading counter-hook in cooperation with kneading vanes; FIG. 5 is a schematic illustration of the interaction of two kneading blades; FIGS. 6 and 7 show two further exemplary embodiments of kneading blades in cooperation with one another.FIG. 1 shows a perspective view of a kneading counterhook, as described, for example, in DE 23 49 106 C2. This kneading counter hook 1 has a hook foot 2 which projects from a base plate 3 which rests on a fastening plate 4. This fixing plate 4 is fixed in a casing wall of a mixing kneader, and the kneading counter hook is projected inside the mixing kneader toward a shaft 11.The kneading counter hook 1 has a part 5 which runs parallel to a housing inner wall, not shown in detail, in the housing longitudinal direction and which, together with the housing wall, forms a kneading gap through which at least one part of a kneading blade 6 shown in FIG. 2 in each case moves. Furthermore, the kneading counter hook 1 has at least its part 7 which is arranged so as to extend in the longitudinal direction thereof at a small distance from the shaft 11. Both parts 5 and 7 are connected to one another by a cutting part 9 extending into the housing as far as the shaft 11, so that a C-shaped hook is produced.A kneading blade 6 cooperating with this kneading counter hook 1 is shown in FIG. 2. It is seated on a disk element 10, which in turn projects from a shaft 11. This shaft passes through a housing, as is shown for example in DE 23 49 106 C2. In the exemplary embodiment shown, both the disk element 10 and the kneading blade 6 have a marginal edge 12.1 and 12.2 designed as a cutting edge.Likewise, the kneading counterhook 1 has a marginal edge 12.3 designed as a cutting edge, this marginal edge extending along the part 7, the cutting part 9, the part 5 and the hook foot 2.In FIG. 3, this marginal edge 12.3 of the kneading counter hook 1 is also shown. This marginal edge 12.3 is formed tapering to a point and has a slope 13. The remaining part lies in a plane with the remainder of the kneading counter hook 1.This kneading counter hook 1 interacts with two kneading blades 6.1 and 6.2, the marginal edges 12.2.1 and 12.2.2 of which are likewise formed tapering to a point with a corresponding slope. They extend approximately parallel along a surface 14 of the counter hook. In this case, they can clean this surface. However, the product is also sheared in the gap 15 between the surface 14 and the edge 12.2.2. In this embodiment, however, the slope 13 ensures that the product is conveyed further substantially in the direction of the arrow 16. Thus, the corresponding elements of this arrangement act not only as mixing and cleaning elements, but also as transport elements for the product.Dashed lines indicate that the marginal edge 12.3 can of course also be arranged in mirror image form and interacts with the kneading blade 6.1. Furthermore, corresponding marginal edges can also be provided opposite one another, whereby the effect of the mixing kneader is ensured even in the case of an inverted rotational direction of the shaft 11. In this case, the marginal edges of the kneading blades 6.1 and 6.2 are also arranged in the opposite direction, as indicated by dashed lines.FIG. 4 shows a further kneading counterhook 1.1, on which a wedge-shaped marginal edge 12.4 rests. This is designed as a quasi isosceles triangle, so that the product stream is not transported further or is merely divided into two partial streams 16.1 and 16.2. The arrows in the kneading blades 6.1 and 6.2 each indicate the direction of rotation or that the kneading blades 6.1 and 6.2 are rotating elements.It can also be seen that the marginal edge 12.4 is not formed to be pointed but bluntly provided with an end face 17, so that this shape of the marginal edge serves to increase the torque in processes in which an increased requirement for mechanical kneading energy or for the division of product agglomerates or product tubers is required.List of reference characters1 Kneading counter hook 2 Hook base 3 Base plate 4 Fastening plate 5 Part 6 Kneading blade 7 Part 8 9 Cutting part 10 Disk element 11 Shaft 12 Edge 13 Slope 14 Surface 15 Gap 16 Arrow 17 End surface 18 Clamping angle 19 Clearance angle

Claims

Device for carrying out mechanical, chemical and / or thermal processes in a product which is located in a housing with mixing and cleaning elements and transport elements on at least one shaft (11) which act on the product, kneading blades (6, 6.1, 6.2) being seated on disc elements (10) and interacting with a kneading counter-hook (1, 1.1) which projects into the interior of the housing in the direction of the shaft (11), characterized in that a peripheral edge (12.3, 12.4) of the kneading counter-hook (1, 1.1) is formed so as to taper or butt with an end face (17), which is adjoined by a face (14) after a bevel (13), and interacts with the kneading blades (6.1, 6.2), wherein their marginal edges (12.2.1, 12.2.2) are also formed tapering with a corresponding slope and run parallel along the surface (14) of the kneading counter hook (1, 1.1).Device according to claim 1, characterised in that the kneading counter hook (1, 1.1) is fixed in the housing.Device according to claim 1 or 2, characterised in that the kneading blades (6.1, 6.2) are arranged rotating with the shaft (11).

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