Drier

Abstract

A drying device for a mixture of a liquid and one or more solids, having a receiving container for the mixture, a rotor that is situated with one section of its circumference in the receiving container, and a drive device for rotatively driving the rotor, the rotor having a plurality of flat entrainment elements, characterized in that the entrainment elements have a radial orientation with respect to a rotational axis of the rotor, wherein at least some of the entrainment elements have a configuration in which relatively narrow entrainment elements alternate with relatively wide entrainment elements in the circumferential direction of the rotor, and/or at least some of the entrainment elements are provided with a plurality of through openings.

Claims

1. A drying device for a mixture of a liquid and one or more solids, having a receiving container for the mixture, a rotor that is situated with only a section of a circumference of the rotor in the receiving container, and a drive device for rotatively driving the rotor, the rotor having a plurality of flat entrainment elements, characterized in that the entrainment elements have a radial orientation with respect to a rotational axis of the rotor, wherein at least some of the entrainment elements have a configuration in which relatively narrow entrainment elements alternate with relatively wide entrainment elements in a circumferential direction of the rotor, and/or at least some of the entrainment elements are provided with a plurality of through openings.

2. The drying device according to claim 1, characterized in that the entrainment elements have a grid-shaped design.

3. The drying device according to claim 1, characterized in that the entrainment elements have an inclined radial orientation with respect to the rotational axis of the rotor such that in each case the distal end of the entrainment elements with respect to the rotational axis is offset compared to the respective proximal end in the circumferential direction.

4. The drying device according to claim 3, characterized in that the entrainment elements are inclined in a direction of a provided rotational direction of the rotor.

5. The drying device according to claim 1, characterized in that through openings of the entrainment elements have an opening surface area of at least 800 mm.sup.2 and/or at most 1600 mm.sup.2.

6. The drying device according to claim 1, characterized by a weighing device for determining a mass of the mixture contained in the receiving container.

7. The drying device according to claim 1, characterized in that the receiving container has an inlet and an outlet for the mixture.

8. The drying device according to claim 7, characterized in that the inlet and the outlet are integrated into opposite sides of the receiving container.

9. The drying device according to claim 8, characterized in that the sides of the receiving container are spaced apart from one another along the rotational axis of the rotor.

10. The drying device according to claim 3, characterized in that the distal end as well as the proximal end are represented by edges of the entrainment elements which run parallel to the rotational axis of the rotor.

11. The drying device according to claim 1, characterized in that the rotor includes two end-face walls which delimit an internal volume of the rotor on the end-face side and which are connected to one another by the entrainment elements.

12. The drying device according to claim 1, characterized in that the drive device includes an electric motor for rotatively driving the rotor.

13. The drying device according to claim 1, characterized by at least one blower, which is arranged to generate a gas stream which flows at least partially through a section of the rotor situated outside the receiving container.

14. The drying device according to claim 13, characterized in that a main flow direction of the gas stream is oriented transversely with respect to the rotational axis of the rotor.

15. The drying device according to claim 13, characterized by a heat exchanger, which is situated between the at least one blower and the rotor such that the air stream flows through the heat exchanger before flowing through the section of the rotor being outside the receiving container.

16. The drying device according to claim 1, characterized in that the entrainment elements, which have a configuration in which relatively narrow entrainment elements alternate with relatively wide entrainment elements in the circumferential direction of the rotor, are arranged such that each relative narrow entrainment elements is positioned between two relative wide entrainment elements.

17. The drying device according to claim 1, characterized in that radially outer edges of the entrainment elements define the circumference of the rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in greater detail below with reference to one exemplary embodiment illustrated in the drawings, which show the following:

(2) FIG. 1: shows a drying device according to the invention in a first perspective view;

(3) FIG. 2: shows the detail denoted by reference numeral II in FIG. 1 in an enlarged illustration;

(4) FIG. 3: shows the drying device in a second perspective view;

(5) FIG. 4: shows the drying device in a view from the front; and

(6) FIG. 5: shows the drying device in a side view, but without an illustration of one of the end-face walls of the rotor and one of the boundary walls of the frame of the drying device.

DETAIL DESCRIPTION

(7) The drying device illustrated in the drawings includes a frame 1 within which a rotor 2 is rotatably supported. A rotating drive of the rotor 2 may be provided by means of a drive device 3 (see FIG. 4) which may include an electric motor, for example, that may act directly, or with the connection of a step-up gear in between, on a central drive shaft 4 whose longitudinal axis corresponds to the rotational axis 17 of the rotor

(8) The frame 1 also integrates a receiving container 5 having a container shell 6, in the shape of a half-shell, whose two (longitudinally axial) ends are closed by means of boundary walls 7. The receiving container 5 is positioned beneath the rotor 2 (with respect to the gravitational direction in an intended operating position of the drying device), the rotor 2 being situated partially inside the receiving container 5.

(9) The internal volume delimited by the receiving container 5 is fluidically connected to two connecting flanges 8 via which a mixture 9 of a liquid and one or more solids may be fed and discharged. One of the connecting flanges 8 is used for discharging mixture 9 that has already been thickened by means of the drying device according to the invention, and accordingly forms an outlet of the receiving container 5, while the other connecting flange 8 is used for feeding new mixture 9 yet to be thickened, and accordingly forms an inlet of the receiving container 5. The connecting flanges 8 are integrated into the sides (boundary walls 7) of the receiving container 5 which are spaced apart from one another along the rotational axis 17 of the rotor 2, and which are opposite from one another and oriented in parallel. One or more pumps or conveying devices (not illustrated) may be provided for feeding and discharging the mixture 9.

(10) Fastened to the frame 1 on one side, at the level of the section of the rotor 2 situated outside the receiving container 5, is a device that includes a plurality of blowers 10 (in this case, two) and a heat exchanger 11. By means of the blowers 10, which may be driven by an electric motor, for example, an air stream may be generated which is oriented approximately perpendicularly with respect to the rotational axis 17 of the rotor 2 and which thus flows through the section of the rotor 2 outside the receiving container 5, transversely with respect to the rotational axis 17 of the rotor. The air stream also flows beforehand through the heat exchanger 11, thus heating the air stream by a transfer of heat energy from a heat exchange medium that is conducted within the heat exchanger 11 and conveyed through the heat exchanger 11 by a circulation pump, for example (not illustrated). To achieve a preferably directed flow through the rotor 2, the device also includes a housing 12 which not only ensures fastening of the device to the frame 1 and fixed positioning of the blower 10 and the heat exchanger 11 with respect to one another, but also has a flow-conducting functionality.

(11) The rotor 2 includes two end-face walls 13 which delimit an internal volume of the rotor 2 on the end-face side and which are connected to one another by a plurality of plate-shaped entrainment elements 14 that are uniformly distributed over the outer circumference of the rotor 2 with an inclined radial orientation with respect to the rotational axis 17 in the rotational direction of the rotor 2 (see in particular FIG. 5). The plate-shaped entrainment elements have a flat, i.e., noncurved, design.

(12) As is also apparent from FIG. 5, the (inclined) radial orientation of the entrainment elements 14 results in an increasing convergence of adjoining entrainment elements 14 with decreasing distance from the rotational axis 17. As a result, the number of entrainment elements 14 that are integratable into the rotor 2 is limited not only by the height h but also by the widths b.sub.1, b.sub.2 of the entrainment elements 14. In order to preferably make maximum use of the annular space of the rotor 2 within which the entrainment elements 14 are situated and which is provided in sections for submerging into the mixture 9 that is provided in the receiving container 5, for integration of a preferably large number of entrainment elements 14, thereby maximizing the surface area that is wettable by the mixture 9, it is provided that relatively wide entrainment elements 14 (having a width b.sub.1) alternate with relatively narrow entrainment elements 14 (having a width b.sub.2) in the circumferential direction of the rotor 2, the narrow entrainment elements 14 each being situated within an approximately V-shaped space which in each case forms adjoining relatively wide entrainment elements 14.

(13) Due to the comparatively large total surface area which is formed by the plate-shaped entrainment elements 14 and which is available for entrainment of the mixture 9 to be thickened, and around which the air stream may flow, a correspondingly good drying or evaporative effect for the liquid portion of the mixture 9 may be achieved.

(14) In addition, in the drying device, despite the relatively large distances between the entrainment elements 14 that result from the relatively large number of entrainment elements 14 that are integrated into the rotor 2, an overall good flow of the air stream through the rotor 2 and the mixture 9 that is entrained by the entrainment elements 14 results due to the entrainment elements 14 having a grid-shaped, in particular a cross grid-shaped, design (see in particular FIG. 2). Accordingly, all of the entrainment elements 14 are completely formed from a plurality of plate-shaped elements which, with the exception of the elements that form the edges of the entrainment elements 14, are connected crosswise to one another and which thus delimit a plurality of mutually penetrating through openings which are rectangular with respect to the longitudinal direction and the width direction of the individual entrainment elements 14, and which form straight longitudinal rows and straight transverse rows.

(15) The end-face walls 13 have ring-shaped sections 15 in which the end-face walls are connected to one another by means of the entrainment elements 14. These ring-shaped sections 15 of the end-face walls 13 are connected to the drive shaft 4 via a plurality of radially oriented braces 16 in order to transfer the rotating drive of the drive shaft 4 to the ring-shaped sections 15 of the rotor 2 which are fastened to the entrainment elements 14.

(16) During operation of the drying device, the rotor 2 is rotatively driven by means of the drive device 3, as the result of which another section of the rotor 2 is submerged on a continuous basis into the mixture 9 accommodated within the receiving container 5, and the entrainment elements 14 thus wetted with the mixture 9 are subsequently moved along the section of the circumference of the rotor 2 not situated in the receiving container 5, the heated air stream flowing around and through the entrainment elements, thus evaporating a portion of the liquid in the mixture 9. The desired thickening of the batch of the mixture 9 contained in the receiving container 5 is achieved in this way. This takes place until the batch of the mixture 9 contained in the receiving container 5 has reached a defined consistency or viscosity. The corresponding batch of the mixture 9 may then be discharged from the receiving container 5 via one of the connecting flanges 8, and a new batch may be fed via the other connecting flange 8 and then appropriately thickened by operating the drying device.

(17) The consistency or viscosity of the mixture 9 to be achieved may be ascertained, for example, by determining a filling level of the mixture 9 within the receiving container 5 that is below a defined level. For determining the filling level, the drying device may have a corresponding filling level measuring device (not illustrated) which may include a radar device, for example. Determining the filling level or the consistency to be achieved may alternatively or additionally be based on weighing the receiving container 5 or the mixture 9 contained in the receiving container 5. The operation of the drying device, including the feeding and discharge of the various batches of the mixture 9 and optionally interrupting the rotating drive of the rotor 2 during the batch change, may thus take place in an automated manner.

(18) The heat energy transferred to the air stream in the heat exchanger 11 preferably represents waste heat from an exothermic process, such as combustion of biogas or some other fuel for power and/or heat generation, that is particularly preferably carried out in the vicinity of the drying device.

(19) Since security systems which reliably prevent escape of mixtures to be thickened by means of a drying device according to the invention must often be provided due to regulatory requirements, among other reasons, in addition to a filling level measuring device that is based on a radar sensor, for example, a further overfill safety device (not illustrated) may be provided for the receiving container 5. This overfill safety device may be based on an oscillating fork, for example, which may be continuously set in oscillation in a known manner, the frequency and/or amplitude of this oscillation changing due to contact with the mixture 9, by means of which an exceedance of a maximum filling level may be detected, which may subsequently result in forced shut-off, for example, of a pump that is to convey the mixture 9 into the receiving container 5. These types of fork sensors are authorized under the German Water Act.

(20) Due to the option for fully automatic operation of the drying device, the drying device may preferably also have an interface (not illustrated) by means of which the drying device may be connected to a higher-level controller. For example, a malfunction report may also be output to a control device via this interface. There is likewise the option for controlling via the interface an agitator unit in a final storage facility in which the thickened mixture 9 is to be stored, as a function of the operation of the drying device. In addition, a drying device according to the invention may also be equipped with a heat flow meter. Such a heat flow meter, in particular in combination with an automatic device for determining the consistency of the mixture 9, may also be used for determining the drying power of the drying device. This may be relevant in particular when the drying device is equipped with a heating device for generating the gas stream used for drying, since in that case the drying power may be set in relation to the heat energy used.

(21) A drying power of one liter of water per kilowatt-hour of heat energy, or better, may be achieved by means of a device according to the invention as illustrated in the drawings, for example. This value is much better than the one and one-half liters of water per kilowatt-hour of heat energy, which must currently be demonstrated as the drying power in order to obtain a cogeneration bonus under the German Renewable Energy Act.

LIST OF REFERENCE NUMERALS

(22) 1 frame 2 rotor 3 drive device 4 drive shaft 5 receiving container 6 container shell 7 boundary wall 8 connecting flange 9 mixture 10 blower 11 heat exchanger 12 housing 13 end-face wall of the rotor 14 entrainment element of the rotor 15 ring-shaped section of the end-face wall of the rotor 16 brace for the end-face wall of the rotor 17 rotational axis of the rotor b1 width of a relatively wide entrainment element b2 width of a relatively narrow entrainment element h height of an entrainment element