EP3163239B1 - Drier - Google Patents

Description

The invention relates to a drying device for a mixture of a liquid and one or more solids.

For example, in agriculture or in the production of biogas arise significant amounts of mixtures of liquids and solids, such as (sewage) sludge, manure or digestate, which must be transported, disposed of and / or processed. In order to minimize transport and storage costs for these mixtures in particular, it is known to thicken these by specifically reducing the proportion of liquid in the mixtures. This can be achieved for example by an at least partial evaporation of this liquid fraction.

For a thickening by partial evaporation of the liquid content of a mixture, for example, a generic drying device can be used which comprises a receptacle for receiving the mixture, a arranged with a portion of its circumference in the receptacle rotor and a drive device for rotating the rotor. Such a drying device is for example from the DE 20 2009 018 720 U1 known. In the local drying device, the rotor is designed as a paddle wheel, as a result of the rotation of the rotor continuously immerse individual of the blades in the mixture to be thickened, take a part of it and wherein the hanging on the blades mixture on the portion of the circumference of the rotor, not in the mixture is submerged, is subject to an increased evaporation effect, which is due to the large-area and thin-layered distribution on the blades. This evaporation effect is considerably assisted by the action of the mixture hanging on the blades with a stream of air generated by a fan, which can also be heated. The surfaces of the blades should be flat, perforated or provided with projections.

The EP 2 805 631 A1 discloses a drum dryer for drying tobacco having a rotatably mounted drum comprising a plurality of lift vanes having different radial and / or axial lengths and / or different angles of incidence relative to a drum body. As a result of this configuration of the lifting blades of the tobacco to fall down at several positions and in several ways through the drum and thereby cover the largest possible cross-sectional area of the drum, which should result in an increase in the contact between tobacco and process air.

One to the drum dryer according to the EP 2 805 631 A1 comparable device is in the US 5,157,849 A disclosed. It is also explicitly disclosed that the drying gas flows through the drum in the longitudinal axial direction.

Furthermore, also discloses the DE 1 230 703 B a drum dryer in which a drum is flowed through in the longitudinal direction of the process gas to dry a good. The drum is divided by partition walls into triangular chambers, wherein within the chambers blade-like plates are arranged, which are intended to effect a constant circulation of the material within the chambers.

The BE 401 889 A discloses a drying device for an aqueous mixture, in particular pasty cement kiln flour, which is to be supplied to a rotary kiln. The drying device comprises a receptacle and a rotor arranged with a portion of its circumference in the receptacle, which is driven in rotation. Exhaust gas from the rotary kiln flows through the rotor, wherein the exhaust gas initially flows from the outside through the shell of the rotor, then flows within the rotor in the transverse direction and passes through the jacket of the rotor elsewhere. Subsequently, the exhaust gas is discharged via an exhaust pipe. The jacket of the rotor can consist of a perforated metal sheet. Furthermore, outside driving elements are attached thereto, which are formed in the form of chains or in the form of rotatably mounted on the jacket of the drum plates.

The invention was based on the object, a generic drying device, as known from DE 20 2009 018 720 U1 is known to improve in terms of their effectiveness.

This object is achieved by means of a drying apparatus according to claim 1. Advantageous embodiments of the drying device according to the invention are subject matters of the dependent claims and will become apparent from the following description of the invention.

A generic drying device for a mixture of a liquid and one or more solids, comprising at least one receptacle for the mixture, a rotor arranged with a portion of its circumference (peripheral portion) in the receptacle, and a drive device for rotatably driving the rotor, wherein the Rotor has a plurality of flat driving elements, according to the invention is characterized in that the driving elements have a radial alignment with respect to a rotational axis of the rotor, wherein at least some, preferably all of the driving elements have a configuration in which relatively narrow driving elements with relatively wide entrainment elements in the circumferential direction alternate and / or that at least some and preferably all of the driving elements are provided with a plurality of through holes.

The entrainment elements are preferably immovably integrated into the rotor and / or preferably have a (in particular flat) plate-like configuration with a length (extension along the axis of rotation of the rotor) and a width (one of the extensions perpendicular to the longitudinal direction) which is considerably larger, in particular at least ten times as large as the height (extension perpendicular to the longitudinal direction and the width direction) are on.

As a "radial" orientation is an orientation of the flat and preferably plate-shaped, driving elements understood, in which a width direction of the Driving elements has at least one exactly radially aligned with respect to the axis of rotation direction component.

The fact that the driving elements have a radial orientation and at the same time alternate relatively narrow entrainment elements with relatively wide entrainment elements in the circumferential direction, the wettable by means of the mixture surface in comparison to that of DE 20 2009 018 720 U1 known drying device can be significantly increased. This is due to the fact that due to the radial orientation of the driving elements whose distances decrease with increasing approach to the axis of rotation, which is relatively broad-dimensioned driving elements (which is generally preferred to achieve the largest wettable surfaces of the driving elements) to a strong approximation and possibly also to a contact of the driving elements would come at their relative to the axis of rotation proximal ends, which in turn, however, a flow through the intermediate spaces formed between the driving elements would be hindered by a provided for the evaporation of a liquid content of the mixture gas and in particular air flow. Such a strong approximation of adjacent driving elements can be avoided according to the invention by alternately using relatively narrow and relatively wide driving elements, wherein all of these driving elements are positioned as far as possible radially outward. This makes it possible to use a comparatively high number of entrainment elements, whereby the total area formed by these can be maximized.

Furthermore, can be achieved by an embodiment of the entrainment with a plurality of through holes that provided for drying the mixture gas flow not only the intermediate spaces formed between the driving elements but also the driving elements themselves and thereby also the mixture adhering to these, which also in the Compared to non-flow-through entrainment elements, the drying effect of the drying device can be significantly improved.

Such an advantageous effect durchstrombarer entrainment may, in particular with an integration of a relatively high number of driving elements, as it is made possible by the configuration of alternating relatively narrow and relatively wide driving elements, positively affect, because the distances between adjacent driving elements are chosen to be particularly small can, without this having a negative effect on the total flow through the rotor and the recorded therein mixture.

For the generation of a relatively large gas flow may preferably be provided that the drying device according to the invention comprises a fan which generates a gas and in particular air flow which at least partially and preferably as completely as possible flows through the rotor or at least the located outside of the receptacle portion thereof. It can preferably be provided that the main flow direction of the gas flow with respect to the axis of rotation of the rotor transversely (preferably ≥ 45 °) and in particular is oriented vertically. Alternatively, however, the main flow direction of the gas flow may also be aligned in the longitudinal direction (≦ 45 °) of the rotor (or the axis of rotation) and in particular also parallel to the axis of rotation.

In a preferred embodiment of a drying device according to the invention can be provided that the driving elements are at least partially formed lattice-shaped. A "lattice-shaped" is understood to mean a configuration in which the entraining elements or the corresponding part thereof are formed from a plurality of interconnected plate-shaped or rod-shaped elements which delimit the plurality of passage openings with one another. "Rod-shaped" elements are characterized in that they have a length (ie extension in one direction, the longitudinal direction) which is considerably larger, in particular at least twice as large as the width (one of the extensions perpendicular to the longitudinal direction) and the height (extension perpendicular to the longitudinal direction and the width direction). In this case, preferably, the width also considerably larger and in particular be at least twice the height. Grid-shaped entrainment elements can be characterized in particular by a relatively large ratio of the plurality of through holes formed total opening area compared to total area of these Durchgangsöffhungen comprehensive sides of the driving elements, at the same time a sufficient stability of the driving elements can be ensured. Preferably, it can be provided that for maximizing the ratio of the total opening area to the total area, the height of the plate-shaped or rod-shaped elements forming the lattice shape of the entrainment elements define the distance between adjacent passage openings. The elements can be designed, for example, in the form of a "parallel lattice" with elements running parallel to one another and thus rectangular and in particular square opening cross-sections or in the form of a diamond lattice with non-parallel elements and thus in particular diamond-shaped opening cross-sections.

In a further preferred embodiment of a drying device according to the invention can also be provided that the driving elements at least partially, preferably all have an inclined radial alignment with respect to the axis of rotation of the rotor. As "inclined radial" orientation is understood when each with respect to the axis of rotation distal end of the driving elements is offset in the circumferential direction compared to the respective proximal end. Particularly preferably, it can be provided that the entrainment elements are inclined in the direction of an intended direction of rotation of the rotor. By means of such a configuration, in turn, an advantageous flow of particular formed between the driving elements spaces can be realized. This can apply in particular when the drying device according to the invention also comprises a fan, wherein the main flow direction of the gas flow generated by this fan is aligned transversely and in particular perpendicular to the axis of rotation of the rotor. Furthermore, by such an inclined radial orientation of Carrier elements improved entrainment of a part of the mixture can be realized from the receptacle.

According to the invention, at least some passage openings of the driving elements have an opening area of at least 800 mm ² . It may preferably be provided that at least some preferably all passage openings of the entrainment elements have an opening area of at most 1600 mm ² . This has proven to be a particularly advantageous compromise from the best possible flowability of the entrainment elements and the best possible effect with regard to entrainment of the mixture from the receptacle.

In order to further improve the drying effect for a drying device according to the invention, it may be provided that this further comprises a heat exchanger, by means of which a gas flow provided for drying and in particular generated by a blower can be heated. Such a heat exchanger can be designed in the form of a heating device in which a conversion of energy of another form of energy (for example electrical energy) into heat energy takes place. However, it can be provided particularly advantageously that (only) a heat transfer from a heat exchange medium (in particular a fluid, that is to say a liquid or a gas or a mixture of liquid and gas) to the gas flow takes place in the heat exchanger. The heat energy stored in the heat exchange medium may particularly preferably be waste heat from another, in particular exothermic process, which is preferably carried out in the immediate vicinity of the drying device according to the invention. This other process may, for example, be a combustion of biogas or another fuel to generate electricity and / or heat.

A drying device according to the invention may preferably have a weighing device for determining the mass of the mixture contained in the receptacle, because with such a particularly accurate degree of already completed drying of the mixture can be determined. This is an embodiment that is basically independent of one inventive design of the drying device and is therefore advantageously implemented in any generic drying devices.

In the case of a drying device according to the invention, it can furthermore preferably be provided that the receiving container has an inlet, which in particular is used exclusively as an inlet, and an outlet, which is used in particular exclusively as an outlet, for the mixture. Compared to a drying device in which a combined inlet and outlet for supplying the mixture into the receptacle and the removal of the mixture is used from the receptacle, thereby in particular the most complete possible removal of the dried and thus only slightly flowable mixture improved become.

Particularly preferably, it can be provided that the inlet and the outlet are integrated into opposite sides of the receptacle, wherein these sides of the receptacle can be arranged spaced apart, in particular, along the axis of rotation of the rotor. In this way, the removal of an already dried batch of the mixture from the receptacle can be supported by simultaneously feeding a new batch.

The separately provided inlets and outlets is an embodiment which is fundamentally independent of an embodiment of the drying apparatus according to the invention and can therefore be advantageously implemented in any generic drying apparatuses.

The indefinite articles ("a", "an", "an" and "an"), in particular in the claims and in the specification generally explaining the claims, are to be understood as such and not as numerical words. Corresponding to this concretized components are thus to be understood that they are present at least once and may be present more than once.

Fig. 1:

eine erfindungsgemäße Trocknungsvorrichtung in einer ersten perspektivischen Ansicht;

Fig. 2:

den in der Fig. 1 mit II gekennzeichneten Ausschnitt in vergrößerter Darstellung;

Fig. 3:

die Trocknungsvorrichtung in einer zweiten perspektivischen Ansicht;

Fig. 4:

die Trocknungsvorrichtung in einer Ansicht von vorne; und

Fig. 5:

die Trocknungsvorrichtung in einer Seitenansicht, jedoch ohne Darstellung einer der Stirnwände des Rotors und einer der Begrenzungswände des Gestells der Trocknungsvorrichtung.

The invention will be explained in more detail with reference to an embodiment shown in the drawings. In the drawings shows:

Fig. 1:

a drying device according to the invention in a first perspective view;

Fig. 2:

in the Fig. 1 marked with II section in an enlarged view;

3:

the drying device in a second perspective view;

4:

the drying device in a view from the front; and

Fig. 5:

the drying device in a side view, but without representing one of the end walls of the rotor and one of the boundary walls of the frame of the drying device.

The drying device shown in the drawings comprises a frame 1, within which a rotor 2 is rotatably mounted. A rotating drive of the rotor 2 can by means of a drive device 3 (see. Fig. 4 ), which may comprise, for example, an electric motor which directly or with the interposition of a transmission gear on a central drive shaft 4, whose longitudinal axis corresponds to the axis of rotation 17 of the rotor 2, can act.

The frame 1 further integrates a receptacle 5, which has a half-shell-shaped container casing 6, whose two (longitudinal axial) ends are closed by means of boundary walls 7. The receptacle 5 is positioned below (relative to the direction of gravity in an intended operating position of the drying device) of the rotor 2, wherein the rotor 2 is partially disposed within the receptacle 5.

The limited by the receptacle 5 inner volume is fluidly connected to two connecting flanges 8, via which a mixture 9 from a liquid and one or more solids and can be removed. One of Connecting flanges 8 serves to discharge already mixed by means of the drying device according to the invention mixture 9 and thus forms an outlet of the receptacle 5, while the other connection flange 8 is used to feed new, still thickening mixture 9 and thus forms an inlet of the receptacle 5. The connecting flanges 8 are integrated into the spaced apart along the rotation axis 17 of the rotor 2, opposite and also parallel aligned sides (boundary walls 7) of the receptacle 5 integrated. For supplying and discharging the mixture 9, one or more pumps (not shown) or conveying devices may be provided.

On one side of the frame 1, at the level of the portion of the rotor 2 located outside the receiving container 5, a device is attached to the frame 1, which comprises a plurality of blowers 10 (in this case, two) and a heat exchanger 11. By means of the blower 10, which may be driven by an electric motor, for example, an air flow can be generated, which is aligned approximately perpendicular to the axis of rotation 17 of the rotor 2 and thus flows through the outside of the receptacle 5 located portion of the rotor 2 transversely to its axis of rotation 17. In this case, the air flow previously passes through the heat exchanger 11, whereby it is heated by a transition of heat energy from a guided inside the heat exchanger 11 and for example by a circulating pump (not shown) through the heat exchanger 11 funded heat exchange medium. In order to achieve the most direct possible flow through the rotor 2, the device also comprises a housing 12, which not only ensures an attachment of the device to the frame 1 and a fixed positioning of the blower 10 and the heat exchanger 11 to each other, but also has a flow-conducting functionality ,

The rotor 2 comprises two end walls 13 which delimit an inner volume of the rotor 2 at the end and the plate-shaped driving elements 14 which are distributed in a uniform pitch over the outer circumference of the rotor 2 and which rotate with respect to the axis of rotation 17 in the direction of rotation of the rotor Rotor 2 inclined radially aligned (see, in particular Fig. 5 ) are interconnected. The plate-shaped driving elements have a flat, ie not curved configuration.

How to continue from the Fig. 5 results from the (inclined) radial orientation of the driving elements 14 a decreasing distance to the rotation axis 17 increasing approach of adjacent driving elements 14. This means that the number of integrable in the rotor 2 driving elements 14 not only by the height h but also the widths b ₁ , b _{2 of} the driving elements 14 is limited. To the annular space of the rotor 2, within which the driving elements 14 are arranged and which is provided in sections for immersion in the provided in the receptacle 5 mixture 9, preferably advantageous for integration of as many driving elements 14 exploit, which in the result of the mixture 9 wettable surface is maximized, it is provided that in the circumferential direction of the rotor 2 relatively wide driving elements 14 (with the width b ₁ ) alternate with relatively narrow driving elements 14 (with the width b ₂ ), wherein the narrow driving elements 14 each within a in approximately V-shaped gap, the respective adjacent relatively wide driving elements 14 form, are arranged.

Due to the comparatively large total area, which is formed by the plate-shaped entrainment elements 14 in total and which is for a Mitnehme the thickening mixture 9 available and can be flowed around by the air flow, a correspondingly good drying or evaporation effect for the liquid content of the mixture. 9 be achieved.

Furthermore, in spite of the relatively small distances between the entraining elements 14, which results from the relatively high number of entrainment elements 14 integrated in the rotor 2, an overall good flow through the rotor 2 and the mixture 9 entrained by the entrainment elements 14 is achieved by the air flow in the drying device realized because the Carrier elements 14 lattice-shaped and concrete cross-lattice-shaped (see, in particular Fig. 2 ). Accordingly, all of the driving elements 14 are formed entirely from a plurality of plate-shaped elements, with the exception of the edges of the driving elements 14 forming elements, cross-shaped interconnected and thereby form a plurality of intersecting straight longitudinal rows and straight transverse rows, with respect Longitudinal direction and the width direction of the individual driving elements 14 limit rectangular Durchgangsöffhungen.

The end walls 13 have annular portions 15 in which they are interconnected by means of the driving elements 14. These annular portions 15 of the end walls 13 are connected via a plurality of radially oriented struts 16 with the drive shaft 4 in order to transmit the rotary drive of the drive shaft 4 to the secured with the driving elements 14 annular portions 15 of the rotor 2.

During operation of the drying device, the rotor 2 is driven in rotation by means of the drive device 3, whereby a different portion of the rotor 2 is continuously immersed in the recorded within the receptacle 5 mixture 9 and the so wetted with the mixture 9 entrainment elements 14 then along the not in the Receiving container 5 located portion of the circumference of the rotor 2 are moved, and these are circulated by means of the heated air flow and through, whereby a portion of the liquid in the mixture 9 evaporates. As a result, the desired thickening of the charge contained within the receptacle 5 of the mixture 9 is achieved. This takes place until the charge of the mixture 9 contained in the receptacle 5 has reached a defined consistency or viscosity. Then the corresponding batch of the mixture 9 can be discharged via one of the connecting flanges 8 from the receiving container 5 and a new batch via the other flange 8 are supplied, which can then be thickened in a corresponding manner by operation of the drying device.

The determination of the consistency or viscosity of the mixture 9 to be achieved can be determined, for example, by dropping below a defined filling level of the mixture 9 within the receiving container 5. In order to determine the filling level, the drying device can have a corresponding fill level measuring device (not shown), which can comprise a radar device, for example. A determination of 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 supply and discharge of the various batches of the mixture 9 and optionally an interruption of the rotating drive of the rotor 2 during the batch change can thereby be automated.

The heat energy transferred to the air flow in the heat exchanger 11 preferably represents waste heat from an exothermic process, which is preferably carried out in the vicinity of the drying device, such as the combustion of biogas or another fuel for power and / or heat generation.

Since, inter alia, due to legal requirements frequently safety systems must be provided which reliably prevent the leakage of thickening by means of a drying device according to the invention mixtures, in addition to an example based on a radar sensor level measuring device, a further overfill protection (not shown) may be provided for the receptacle 5. This Überfüllsicherung can for example be based on a tuning fork, which can be continuously vibrated in a known manner, with the frequency and / or amplitude of this vibration due to contact with the mixture 9 changes, which can safely be detected exceeding a maximum level, which may subsequently lead to a forced shutdown, for example, of a pump 9 to be conveyed to the mixing container 9 in the receiving container 5. such Tuning fork sensors are approved according to the German Water Resources Act.

As a result of the possibility of fully automatic operation of the drying device, this may preferably still have an interface (not shown), by means of which it can be connected to a higher-level control. For example, a fault message to a control device can also be output via this interface. It is also possible, via the interface, to control an agitator in a repository, 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 still be equipped with a heat meter. Such a heat meter, in particular in combination with an automatic device for determining the consistency of the mixture 9, can also serve to determine the drying performance of the drying device. This can be particularly relevant if it is equipped with a heating device for heating the gas stream used for drying, because then the drying performance can be set in relation to the heat energy used.

By means of a drying device according to the invention, as shown for example in the drawings, a drying capacity of one liter of water per kilowatt hour of heat energy and better can be achieved. This value is significantly better than the one and a half liters of water per kilowatt hour of heat energy that currently has to be detected as drying capacity in order to receive a bonus for combined heat and power (CHP bonus) according to the German Renewable Energy Sources Act (EEG) ,

LIST OF REFERENCE NUMBERS

1

frame

2

rotor

3

driving device

4

drive shaft

5

receptacle

6

container jacket

7

boundary wall

8th

flange

9

mixture

10

fan

11

heat exchangers

12

casing

13

Front wall of the rotor

14

Driving element of the rotor

15

Annular section of the end wall of the rotor

16

Strut the front wall of the rotor

17

Rotation axis of the rotor

b1

Width of a relatively wide driving element

b2

Width of a relatively narrow driving element

H

Height of a driving element

Claims (9)

1. A drying device for a mixture (9) of a liquid and one or more solids, having a receiving container (5) for the mixture (9), a rotor (2) that is situated with one section of its circumference in the receiving container (5), and a drive device (3) for rotatively driving the rotor (2), the rotor (2) having a plurality of flat entrainment elements (14), whereby the entrainment elements (14) have a radial orientation with respect to a rotational axis (17) of the rotor (2), characterized in that at least some of the entrainment elements (14) have a configuration in which relatively narrow entrainment elements (14) alternate with relatively wide entrainment elements (14) in the circumferential direction of the rotor (2), and/or at least some of the entrainment elements (14) are provided with a plurality of through openings, whereby at least some of the through openings of the entrainment elements (14) have an opening surface area of at least 800 mm²,
2. The drying device according to Claim 1, characterized in that the entrainment elements (14) have a grid-shaped design.
3. The drying device according to Claim 1 or 2, characterized in that the entrainment elements (14) have an inclined radial orientation with respect to the rotational axis (17) of the rotor (2).
4. The drying device according to Claim 3, characterized in that the entrainment elements (14) are inclined in the direction of a provided rotational direction of the rotor (2).
5. The drying device according to one of the preceding claims, characterized in that through openings of the entrainment elements (14) have an opening surface area of at most 1600 mm².
6. The drying device according to one of the preceding claims, characterized by a weighing device for determining the mass of the mixture (9) contained in the receiving container (5).
7. The drying device according to one of the preceding claims, characterized in that the receiving container (5) has an inlet and an outlet for the mixture (9).
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 (5).
9. The drying device according to Claim 8, characterized in that the sides of the receiving container (5) are spaced apart from one another along the rotational axis (17) of the rotor (2).

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