Agitating – Stirrer within stationary mixing chamber – Rotatable stirrer
Reexamination Certificate
2000-05-24
2002-03-12
Cooley, Charles E. (Department: 1723)
Agitating
Stirrer within stationary mixing chamber
Rotatable stirrer
C366S305000, C366S307000, C366S314000
Reexamination Certificate
active
06354728
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for producing a pourable product, in particular a pourable product with a coating. The device includes a guide vane. The invention further relates to various methods for using the device.
A pourable product is understood to be the finished product in the respective application of the invention. In this case, the pourable product may be composed basically of the same or different starting materials with a radially homogeneous or layered structure.
The pourable product may be of any kind, insofar as it is possible to put both this and the respective starting materials into radially peripheral circulation.
2. Description of Related Art
According to the prior art, various methods and devices for the granulation of starting materials or the coating of cores are known.
DE 41 28 258 A1 specifies a method for the uniform closed coating of grains, such as seed grains, by means of a rotor granulator with integrated fluidized-bed drying and a device for carrying it out. According to the method, the batch circulated by the running rotor and containing the dissolved or suspended coating materials is sprayed through one or more nozzles arranged in the free inner space of the stator and assisted by compressed air, warm air being introduced through the annular gap between the rotor and stator into the space containing the circulated batch. The associated device specifies a rotor, the cross section of which decreases from the center at an angle of up to 45° to the plane and is curved upward at the outer circumference, with a radius of about 10 to 20% of its diameter, to an edge angle of 45°. Located above the rotor in the stator, the deflecting funnel, is a thin-walled rotationally symmetric annular screen surface or annular gap surface which is surrounded on the outside by an air duct.
DE 4411058 C2 specifies a device for the coating of granular material, in particular for the coating of seed with chemicals, such as dressing agents. The device has a conically upwardly widened side wall of a mixing cylinder which rotates at high speed and which is rotatable about a vertical axis. The liquid chemicals are sprayed via a spraying means onto the granular material located in the mixing cylinder. For better intermixing of the granular material in the mixing chamber, bent diverting blades are arranged above the mixing cylinder on a discharge ring, said diverting blades deflecting the material and leading it back downward into the conical mixing cylinder.
The solutions according to the prior art often have relatively low productivity or can be used only to a limited extent for coatings. For example, the diverting blades engage into the material, and delicate products or their coatings, for example in the form of a pasty enveloping layer, are destroyed.
SUMMARY OF THE INVENTION
The object on which the invention is based is to specify a device for producing a pourable product, in particular a pourable product with a delicate structure or coating, of the type initially mentioned, which ensures high quality and productivity at a relatively low technical outlay. The invention relates, furthermore, to two methods for using the device.
Starting materials within the meaning of the invention are to be understood basically as all materials which are introduced into the device. These may be pulverulent materials, from which basic cores in the form of a granulate are produced, particularly in cooperation with a binder. In one use of the device, an enveloping layer consisting of the same or different starting materials can be built up on these basic cores or any other cores.
The “other” cores which may be coated are, for example, granulates, pellets, grains, seed grains, tablets, pills and the like. In this case, the cores may be homogeneous or an agglomerate or a core which has already been coated previously with one or more layers.
A coating is a layer which is built up or precipitated on a core in such a way that the core is surrounded essentially uniformly.
The coating may be composed of a material, a liquid or dispersion or of a mixture of a plurality of materials, for example of a conglomeration (snowball effect) of a pulverulent starting material and a liquid binder. The pulverulent starting material may, in this case, be a homogeneous material or mixture of a plurality of materials. It is often a neutral material which serves merely, in conglomeration with the liquid binder, for enveloping the core and at the same time giving the product as uniform a shape as possible with the same dimensions. Both the pulverulent starting material and the binder may also contain active substances intended for the envisaged use.
In order to simplify the remaining description of the invention, both the basic cores and the “other” independent cores are designated below, in general, only as cores, and starting materials are to be understood accordingly as the starting materials which are introduced into the device in order to form the basic cores or to apply an enveloping layer to existing cores.
An important aspect of the invention is that the starting materials, in particular the cores used, and ultimately the finished pourable product itself are put into a specific circulating movement by the rotor.
The starting materials or the cores are put by the rotor into a radially tangential direction of movement which is changed to a vertically tangential direction in the outer region of the rotor and in the vicinity of the wall of the rotor chamber.
Consequently, the cores leave the active region of the rotor with a kinetic energy which is sufficient for the cores to roll along on the guide vanes arranged statically on the rotor chamber and, at the same time, to change their direction of movement positively according to the shape of the guide vanes and essentially be deflected and fall back into the rotor.
The radially tangential direction of movement of the cores is inclined upward, at least in the radially outer third of the rotor, at an angle of between 10° and 80° to the axis of rotation, until the cores on the wall of the rotor chamber leave the rotor upward in a vertically tangential direction with kinetic energy. The inclination, which is advantageous in practice, is determined in each case by the mass of the cores or of the pourable products in conjunction with the diameter of the rotor and the rotational speed of the latter.
The cores are put, as a whole, into specific intensive, essentially concussion-free circulation, in which the cores and, in particular, the enveloping layers growing on the cores are not exposed to any adverse compressive and concussive loads.
According to the invention, the guide vanes are arranged statically on the inner wall of the rotor chamber above the plane of the upper edge of the rotor. In cross section relative to the rotor axis, they have essentially the shape of a segment of a circle or of a spiral. The outer ends of the segments emerge from the circle of the inner wall of the rotor chamber in the direction of rotation of the rotor, the tangents of the inner wall and of the guide vanes at the contact point having essentially the same inclination. The inner ends of the segments lie approximately in the middle part of the rotor radius.
By virtue of this specific configuration, the circulating product, in particular with delicate enveloping layers, can roll on the rotor, essentially free of concussion, under the influence of the kinetic energy, leave said rotor and roll on the inside of the guide vanes until it falls back into the rotor.
The cores do not, in particular, impinge onto angular fittings, for example on circulation obstacles, such as are used according to the prior art.
The cores roll intensively and uniformly on the guide vanes and against one another, so that they are exposed essentially on all sides to identical compressive loads and a uniform coating is formed.
Where thicker enveloping layers are used as a coating, it may also be advantageous to vary the guide vanes specifically as a funct
Bretschneider Frank
Brückner Jürgen
Peter Bruno
Cooley Charles E.
Glatt Systemtechnik Dresden GmbH
Jacobson & Holman PLLC
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