ROLL ASSEMBLY, IN PARTICULAR FOR WATER TREATMENT, AND TREATMENT APPARATUS

Abstract

A roll assembly for increasing a surface area of a fluid, in particular for water treatment, including at least one shaft which in each case bears at least one roll, a drive for the at least one shaft, a fluid feed which is arranged above the respective roll and guides the fluid to the respective roll, and a collecting trough for the fluid, the collecting trough being assigned to the respective roll, wherein the roll has two lateral surfaces in the shape of cylinder jackets which are spaced apart in the radial direction, are each in the form of a mesh and project on the bottom side of the roll into the collecting trough.

Claims

1. A roll assembly for increasing a surface area of a fluid, in particular for water treatment, comprising at least one shaft which in each case bears at least one roll, a drive for the at least one shaft, a fluid feed which is arranged above the respective roll and guides the fluid to the respective roll, and a collecting trough for the fluid, said collecting trough being assigned to the respective roll, wherein the roll has two lateral surfaces in the shape of cylinder jackets which are spaced apart in the radial direction, are each in the form of a mesh and project on the bottom side of the roll into the collecting trough.

2. The roll assembly according to claim 1, wherein the outer of the lateral surfaces has a spacing of less than 3 mm or less than 2 mm or less than 1.5 mm from a base of the collecting trough.

3. The roll assembly according to claim 1, wherein at least the outer surface area of the outer of the lateral surfaces has a sawtooth form, apart from the mesh apertures in the circumferential direction.

4. The roll assembly according to claim 1, wherein the inner and/or outer of the lateral surfaces is formed by a rhomboidal mesh, in particular by a rhomboidal expanded mesh.

5. The roll assembly according to claim 1, wherein the fluid supply is formed by a pipe which, at least in one axial portion that extends above the outer lateral surface in the axial direction of the shaft, has a slot through which fluid conducted in the pipe can escape from the pipe.

6. The roll assembly according to claim 1, wherein the respective roll comprises a fluid-tight inner shell which is in the form of a cylinder jacket and extends between the shaft and the inner of the lateral surfaces.

7. The roll assembly according to claim 1, wherein it comprises a first shaft which bears a first roll, to which a first collecting trough is assigned, and a second shaft which runs parallel to the first shaft and bears a second shaft, to which a second collecting trough is assigned, wherein the first collecting trough and the second collecting trough are arranged adjacent to one another in a direction perpendicular to the axial direction of the rolls, wherein a side wall of the first collecting trough at the same time forms a side wall of the second collecting trough or is connected fluid-tightly to a side wall of the second collecting trough.

8. The roll assembly according to claim 1, wherein it comprises a plurality of shafts, wherein the shafts are mounted on a housing and penetrate at least one housing wall of the housing, and/or wherein the shafts, in particular outside the housing, are coupled in terms of movement to one another, and/or the fluid feeds of the rolls arranged on the shafts are connected to a common pump for loading the fluid feeds with the fluid.

9. A treatment apparatus for fluid treatment, with a fluid vessel which comprises a fluid inlet for supplying fluid to be treated, and a fluid outlet for conducting away treated fluid, wherein it comprises a roll assembly according to claim 1, wherein an intake opening of the fluid vessel is fluidically connected to the at least one fluid feed, in particular via the or a pump, wherein a fluid outflow of the roll assembly, to which fluid passing via the or a side wall of the at least one collecting trough can be supplied, opens into the fluid vessel.

10. The treatment apparatus according to claim 9, wherein the roll assembly is arranged in the or a housing which has a cavity which is laterally adjacent to the collecting trough or to at least one of the collecting troughs, is open on its bottom side and into which the fluid vessel opens and thus forms the fluid outflow of the roll assembly.

11. The treatment apparatus according to claim 9, wherein it has a fluid-deflecting plate which projects into the fluid vessel and ends freely in the fluid vessel, wherein the fluid inlet of the fluid vessel and the fluid outflow of the roll assembly are arranged on one side of the fluid-deflecting plate and the fluid outlet of the fluid vessel and/or the intake opening are arranged on the opposite other side of the fluid-deflecting plate.

12. The treatment apparatus according to claim 11, wherein the fluid outlet of the fluid vessel is arranged above the free end of the fluid-deflecting plate, wherein the intake opening is arranged lower than the fluid outlet, in particular below the free end of the fluid-deflecting plate.

13. The treatment apparatus according to claim 9, wherein it has at least one pair of electrodes which project into the fluid vessel, wherein an electrolysis device is designed to charge the electrodes with voltage in order to carry out electrolysis of the fluid.

14. The treatment apparatus according to claim 9, wherein at least one gas feed line opens into the or a housing of the roll assembly, said gas feed line being fed through a gas discharge opening on the upper side of the fluid vessel.

15. The treatment apparatus according to claim 14, wherein a foam breaker is arranged at the gas discharge opening.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0053] In the drawing:

[0054] FIG. 1 shows an exemplary embodiment of a treatment apparatus according to the invention which comprises an exemplary embodiment of the roll assembly according to the invention,

[0055] FIG. 2 shows the exemplary embodiment illustrated in FIG. 1 of the roll assembly according to the invention, and

[0056] FIGS. 3-5 show detailed views of this roll assembly.

DETAILED DESCRIPTION OF THE INVENTION

[0057] FIG. 1 shows a treatment apparatus 1 for fluid treatment. Said treatment apparatus comprises a fluid vessel 28, to which fluid for processing is fed via a fluid inlet 2. After the processing, the fluid is discharged from the fluid vessel 28 via the fluid outlet 3.

[0058] The fluid treated can in particular be water which is laden with foreign matter, in particular with colloids. The treatment apparatus can serve here in particular to treat colloids and other suspended matter in water, which cannot be readily removed by flocculation or addition of activated carbon within the scope of physical separation or can be removed only with long downtimes, in such a manner that they or constituents remaining after oxidation or the like can after such treatment be readily separated off by flocculation or addition of activated carbon, or under some circumstances even precipitate directly.

[0059] The treatment apparatus 1 which is shown can thus be used in particular within an extensive water treatment facility. For example, solids can already be separated off by pressing and/or filtering in upstream processing steps and foreign matter which can be readily flocculated can already have been flocculated. In addition or alternatively, foreign matter can already previously be oxidized or hydrated, for example in order to break open certain long-chain molecules even before the fluid is introduced into the fluid vessel 28.

[0060] As will be explained more precisely later, it is advantageous if the fluid which is supplied to the treatment apparatus 1 comprises at least a certain quantity of tensides or the like, in particular in order to bind non-polar foreign matter or foreign matter with low polarity in the fluid to said tensides or the like and thus to isolate them and, for example, to make them accessible for later flocculation. It is assumed below that there are already sufficient quantities of tensides or similarly acting substances in the fluid supplied via the fluid inlet 2. In principle, it would also be possible to introduce tensides or other desired additives into the fluid vessel in a targeted manner.

[0061] In the exemplary embodiment, the fluid flowing in via the fluid inlet 2 initially passes electrodes 5 of an electrolysis device that are charged with voltage by the latter in order in particular to cleave water into oxygen and hydrogen. Only two of the electrodes 5 are shown here in FIG. 1, but a plurality of said pairs of electrodes are preferably arranged offset with respect to one another perpendicular to the plane of the drawing in FIG. 1 in order to provide a large reaction surface for the electrolysis. It is advantageous here if the electrolysis device is designed in such a manner that a respective pair of electrodes 5 is in each case operated after a certain period of time with reverse polarity, i. e. if anode and cathode are swapped so as to avoid an accumulation of salt on the electrodes 5. For example, such a reversal of polarity can take place once per minute.

[0062] The electrolysis of the water has the effect, on the one hand, that a high oxygen content and also a significant content of ozone or oxygen radicals are present in the air situated above the fluid surface, which, as will be discussed in more detail further below, can contribute to the breakdown of foreign matter in the roll assembly 8. Furthermore, at least locally in the region of the respective electrodes, a higher concentration of H.sub.3O.sup.+ and OH.sup.− radicals than would otherwise be present in the water is achieved. This can locally contribute to the hydration of foreign matter, because it is for example no longer necessary to separate a hydrogen atom from the water molecule in order to utilize an OH— group for the hydration of a molecule.

[0063] If the circulation of the fluid within the context of the treatment, as discussed in more detail further below, furthermore results in a flow speed that is sufficiently high, the elevated H.sub.3O.sup.+ and OH.sup.− concentrations can also be present in other regions of the treatment apparatus 1, in particular in the roll assembly 8, because the transport of fluid can take place more quickly than a neutralization of H.sub.3O.sup.+ and OH.sup.− radicals by diffusion processes. The electrolysis by the electrodes 5 can thus promote oxidation processes and hydration processes of foreign matter in the water.

[0064] A fluid-deflecting plate 6 is arranged in the fluid vessel 28 in such a manner that the fluid inlet 2 and a fluid outflow of the roll assembly 8, discussed again further below, are arranged on the same side of said fluid-deflecting plate 6, whereas the fluid outlet 3 of the fluid vessel 28 is arranged on the other side of the fluid-deflecting plate 6. This has the effect that fluid that is fed via the fluid inlet 2 cannot flow directly to the fluid outlet 3, but rather is mixed with the fluid that has already been treated in the roll assembly 8, as a result of which the concentration of still-unprocessed foreign matter in the fluid is considerably reduced.

[0065] Since the fluid mixed in this way is furthermore, on its flow path to the fluid outlet 3, conducted past an intake opening 29 via which it is drawn in by means of the pump 7 and conveyed via the pipe 9 to the roll assembly 8, it can be achieved, through corresponding setting of the conveying rate of the pump in relation to the fluid quantity 1a that is fed via the fluid inlet 2 and discharged by the fluid outlet 3, that fluid which is supplied is, on average, conducted through the roll assembly 8 several times before being discharged via the fluid outlet 3. In this way, for the fluid in the fluid vessel 28 and in particular for the fluid that is discharged via the fluid outlet 3, a very low concentration of still-unprocessed foreign matter can be achieved.

[0066] As explained, the treatment apparatus 1 serves primarily to process foreign matter in the fluid in such a manner that they can be subsequently readily precipitated. Proportions of the foreign matter may nevertheless precipitate already in the treatment apparatus 1 itself. For example, in the case of the treatment of water that has been recovered from fermented slurry, for example from a biogas plant, relatively high pH values are encountered, such that, after a break-up of organometallic compounds, hydroxides of the metals are precipitated in most cases. In addition, it is possible for the supplied fluid to already contain activated carbon and/or flocculants that have been introduced into the fluid, for example in the previous processing steps. A sediment with a high concentration of precipitated foreign matter can thus form in the fluid vessel 28, which sediment can be extracted via a drain opening 4 situated close to the base.

[0067] In order to achieve high throughputs with relatively compact dimensions of the treatment apparatus, on the one hand, and a low level of remaining unprocessed foreign matter in the fluid, on the other hand, the roll assembly 8 is utilized in the treatment apparatus 1 to enlarge the surface area of the fluid and generally increase the dynamics of reactions for the treatment. A detailed view of the roll assembly 8 is illustrated in FIG. 2. In the example, the roll assembly 8 comprises six rolls 16, 16′, which are supported by a housing 36 of the roll assembly 8 and which are driven by a common drive 18. The drive 18 is merely schematically illustrated in FIG. 2. The drive 18 may for example be an electric motor. The drive 18 may for example be coupled directly to the shaft 35, illustrated in FIGS. 3 and 4, of one of the rolls 16, 16′. The shafts 35 of the various rolls 16, 16′ may be coupled to one another in terms of movement, for example by means of V-belts.

[0068] The fluid that is drawn in by the pump 7 via the intake opening 29 is conducted via the pipe 9 to respective apertures 13 of the housing 36 of the roll assembly 8, which apertures are adjoined by water feeds 14 which conduct the inflowing fluid axially along the roll 16 and cause said fluid to flow through a gap or slot 15 or some other opening onto an outer lateral surface 23 of the respective roll 16, 16′. In the example shown, the fluid feeds 14 are formed by rectangular pipes with a gap or slot 15 running in the longitudinal direction of the pipe at or close to the lowest point. Other configurations would also be possible. It is essential that the fluid is applied to the outer lateral surface 23 in a manner distributed at least approximately uniformly along the axial direction of the respective shaft 16, 16′.

[0069] The respective rolls comprise, as can be seen in particular in FIGS. 3 and 4, two cylindrical lateral surfaces 22, 23 which are spaced apart from one another in a radial direction and which are each formed by a mesh. One example of such a mesh is illustrated in FIG. 5. Below the roll 16, 16′, there is arranged a respective collecting trough 17, 17′ which collects the fluid supplied via or by means of the roll 16, 16′. Here, the dimensions of the lateral surfaces 22, 23 are selected such that they project into the collecting trough 17, 17′ at the bottom side of the roll 16, 16′. Furthermore, radially within the inner lateral surface 22, there is situated a cylindrical inner shell 21, which is likewise connected rotationally conjointly to the shaft 35. As indicated by the arrow 34, the respective shaft 35 and thus the rolls 16, 16′ are rotated with a relatively high rotational speed of, for example, 1000 rpm.

[0070] The described arrangement has the effect that, in the case of the collecting trough 17′ being filled to a sufficient level with fluid, the two lateral surfaces 22, 23 dip into the fluid and, owing to the lateral surfaces 22, 23 being in the form of meshes and owing to the relatively fast rotation of the rolls 16, 16′, intensely swirl said fluid and entrain said fluid at least over a certain distance. Thus, in the intermediate spaces 30, 31 between the lateral surfaces 22, 23 and between the inner shell 21 and the lateral surface 22, which may for example have an extent of 1 to 1.5 cm in a radial direction, there is resulting hydrodynamic fluid movement and swirling of the fluid. This leads, on the one hand, to an acceleration of treatment processes within the fluid, that is to say for example of hydration of foreign matter.

[0071] On the other hand, in particular if tensides or other foaming agents are present in the fluid, there will result an intense foam formation, wherein the lateral surfaces 22, 23 in the form of meshes however simultaneously act as mechanical foam breakers, such that the foam or individual air bubbles in the foam have a very short lifetime of for example only approximately 2 ms. The interaction of the intense foam formation with the simultaneous rapid breakdown of the foam has the effect that very large surface areas are briefly provided, but at the same time a high throughput of fluid can be achieved.

[0072] As has already been explained in detail in the general part of the description, the formation of large surfaces leads, on the one hand to foreign matter in the fluid being able to interact to a considerably greater extent with supplied air, which, as explained above, can in particular have a particularly high content of oxygen or ozone. On the other hand, tensides present in the fluid are adsorbed on said surface and can thus form a large filter surface area in order to act on and to kill foreign matter, for example organic residues of oxidized molecules or viruses or bacteria.

[0073] As a result of the rotation of the rolls 16, 16′, fluid situated in the respective collecting trough 17, 17′ tends to be accelerated to the right in FIG. 2, such that, for the collecting trough 17, the fluid is sloshed or conveyed over the side wall 38 of the collecting trough 17, following which said fluid can fall vertically through the cavity, situated to the right of the collecting troughs 17, of the housing 36 of the roll assembly 40, which cavity forms the fluid outflow of the roll assembly 8, back into the fluid vessel 28, specifically on the left-hand side of the fluid-deflecting plate 6. This results in the mixing with freshly supplied fluid, as already discussed above.

[0074] Here, fluid that is situated in the collecting trough 17′ is firstly conveyed into the collecting trough 17, because the side walls 38 of the collecting troughs 17, 17′ are connected to one another in fluid-tight fashion. This has the effect, on the one hand, that fluid that is initially fed to the rolls 16′ can be processed twice in the roll assembly, specifically once by the roll 16′ and once by the roll 16. At the same time, this has the effect that the fluid that is fed to the roll 16 is diluted with the pre-processed fluid fed from the roll 16′, such that a lower concentration of still-unprocessed foreign matter is present in the region of the roll 16 than is the case for the roll 16′. As already explained in the general part, it has been recognized that the combination between a serial and a parallel processing of the fluid is particularly advantageous.

[0075] FIG. 4 shows one option for constructing rolls 16, 16′ and of mounting them on the housing 36 of the roll assembly 8. The housing walls 37 of the housing 36 of the roll assembly are illustrated by dashed lines. The housing walls 37 support a shaft 35 to which four supporting disks 20 are fastened. One pair of the supporting disks 20 in each case supports the inner and outer lateral surface 22, 23 in the shape of cylinder jackets and the inner shell 21, which is fluid-tight. Two rolls which are connected rotationally conjointly to the shaft 35 are thus formed in FIG. 4.

[0076] In the example shown, the shaft 35 is conducted on both sides through the respective housing wall 37 of the housing 36. This can serve for example to couple the shafts 35 to one another in the region of one of the housing walls 37, for which purpose a belt pulley 19 is provided on the shaft 35 in FIG. 4. Said belt pulley can be coupled to a respective shaft disk of one or more further shafts via a V-belt, for example. One of the shafts 35 can be driven directly, for example by one end of the shaft being coupled to the output shaft of the drive 18 in the region of the opposite housing wall 37.

[0077] The mesh which is illustrated by way of example in FIG. 5 and which forms the lateral surfaces 22, 23 can be designed in such a manner that the sawtooth surface structure illustrated schematically in FIG. 3 results. This leads overall, in conjunction with a small spacing between the outer lateral surface 35 and the base of the collecting trough 17, to a good break-up of hydrate shells and water clusters, which can suppress a reaction of foreign matter in the fluid. The fluid is hereby initially intensely compressed in the region 32 and subsequently suddenly expanded in the region 33. Together with the shear forces that arise in the constriction, water clusters can be broken up in this way.

[0078] A corresponding sawtooth structure for meshes results for example in the case of production of a rhomboidal mesh as an expanded mesh. If, for example, the apertures 24, illustrated in FIG. 5, between the mesh bars 25 are produced by slots initially being introduced and the mesh subsequently being expanded in the vertical direction in FIG. 5; this leads to an offset of the mesh bars 25 such that, for example, the edge 26 in FIG. 5 can be located considerably closer to the observer than the edge 27.

[0079] In order to firstly further assist the foam formation within the roll assembly and secondly achieve the high oxygen and ozone concentration, which occurs owing to the electrolysis of the fluid, also in the region of the rolls 16, 16′, use is made of gas feed lines 10 which are fed through a gas discharge opening at the top side of the fluid vessel 28. Since in particular the operation of the roll assembly 8 can have the effect that a foam layer forms on the surface of the fluid in the fluid vessel 28, and it is advantageously sought to prevent the gas discharge opening or the gas feed lines 10 from being covered with foam, which would restrict a feed of gas to the roll assembly 8, a foam breaker 11 is arranged in the region of the gas discharge opening, which foam breaker, in the example, is driven by an electric motor 12. As a foam breaker, use may for example be made of a disk with rods attached thereto, as is illustrated schematically in FIG. 1. Here, the rods are led rapidly through the foam and thus connect air bubbles, leading to the break-up of the foam. Alternatively or additionally, the foam can be broken up by baffle plates at which the foam bubbles burst.

[0080] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.