mud separator

Description

[0001] The present invention relates to a sludge separator, particularly for a vehicle wash system, comprising a sedimentation basin with a side wall and a bottom. The sedimentation basin is vertically divided into a lower sediment zone, an intermediate zone, and an upper liquid exchange zone. Furthermore, the sludge separator has an inlet for supplying a liquid containing solid particles into the sedimentation basin, which has an end section with an inlet opening. The inlet opening is arranged vertically in the upper liquid exchange zone and opens horizontally into the sedimentation basin at a peripheral point. The sludge separator also has an outlet for discharging liquid from the sedimentation basin, which has an outlet opening arranged vertically in the upper liquid exchange zone.

[0002] From EP 2 463 444 D1, a sludge separator for separating particles contained in a liquid is known. The sludge separator has an upper inlet opening, a separator housing, and a lower outlet opening. The inlet and outlet openings are arranged coaxially with the vertical housing axis. The sludge separator is traversed vertically from the upper inlet opening to the lower outlet opening. The supplied liquid passes through a particle separator with flow deflection elements, which cause a flow redirection between the axial and radial directions. The substances to be separated are separated by these flow deflection elements. They settle in a collection container and are then discharged via a drain line.

[0003] Furthermore, sludge separators are known that operate according to the cyclone principle. For example, WO 2009 / 122127 A1 describes a sludge separator with a pot-shaped separator vessel having an inlet in the upper part of the vessel for supplying liquid and an outlet in the upper part of the vessel for discharging the liquid. A pipe open at the bottom is arranged coaxially inside the separator vessel. The outlet is connected to the interior of the pipe, while the inlet opens into an annular space between the vessel wall and the pipe. The inlet and outlet are arranged such that liquid introduced into the separator vessel flows downwards along the vessel wall in a cyclone-like motion and then, within the downward-flowing liquid, flows upwards through the pipe to the outlet.Solid particles released by the cyclone action sink down the container wall into a sludge settling chamber located at the bottom of the container.

[0004] Further sludge separators based on the cyclone principle are known from EP 2 893 981 A1 and EP 3 222 357 B1.

[0005] From DE 94 14 562 U1, a sludge trap for wastewater contaminated with settleable solids is known. The sludge trap consists of a settling basin with a lower lateral inlet and an upper outlet. The inlet opening is oriented approximately tangentially to the wall of the settling basin. The upper outlet is located approximately in the center of the settling basin. Furthermore, the central upper outlet is surrounded at a distance by a permeable, hollow-body-shaped insert positioned vertically around it. The geometry of the inlet and outlet creates a spiral flow around the hollow-body-shaped insert, which flows in a spiral from bottom to top towards the outlet.

[0006] A separator system with a similar sludge trap is described in DE 94 12 973 U1. The sludge trap of this separator system is intended, for example, to separate settleable solids in the wastewater of a car wash.

[0007] Furthermore, a separator tank is known from DE 92 08 367 U1, which can be used either as a sludge trap or as a pre-separator with an inlet and an outlet. In this separator tank, the inlet and outlet are located at approximately the same height in the upper region, opposite each other at the edge of the tank. When used as a sludge trap, baffle plates are mounted at the inlet and outlet.

[0008] In a sludge separator, such as one used in a vehicle wash, particularly a gantry car wash, the wastewater from the wash system should be treated in such a way that solid particles carried by the wastewater settle out in the sedimentation tank. Firstly, the separation efficiency of the sludge separator should be as high as possible. Secondly, it should be possible to continuously or intermittently add wastewater to the sedimentation tank during operation of the car wash without making the sedimentation tank too large. This also means that liquid should be continuously or intermittently discharged from the sedimentation tank.

[0009] With known sludge separators used in car washes, the problem arose that the separation efficiency was insufficient. Too many solid particles, which were fed into the sedimentation basin with the wastewater, remained in the discharged liquid. Furthermore, a high nitrate concentration was found at the outlet. However, a high nitrate concentration in the liquid discharged from the sludge separator should be avoided.

[0010] US Patent 2007 / 0267342 A1 describes a separation system for retaining floating and non-floating particles in a storage chamber of a treatment tank. The storage chamber includes an inlet and an outlet. The outlet is positioned within the storage chamber such that the primary and secondary fluid flow patterns within the chamber are minimally disturbed. A circular or rotating flow pattern is generated within the storage chamber, and the outlet opening of the storage chamber is centered on an axis of this circular flow pattern.

[0011] EP 0703324 A1 describes a sludge trap for wastewater contaminated with settleable solids, consisting of a settling basin with an upper lateral inlet and an upper outlet. The inlet opening is oriented at least approximately tangentially to the wall of the settling basin, and the upper outlet is located approximately in the center of the settling basin.

[0012] The present invention is therefore based on the objective of providing a sludge separator which has an improved separation performance for solid particles which are fed to the sedimentation basin via the introduced liquid.

[0013] According to the invention, this problem is solved by a sludge separator with the features of claim 1. Advantageous embodiments and further developments are described in the dependent claims.

[0014] According to the invention, in the sludge separator described above, the end section is oriented such that the supplied liquid flows tangentially into the sedimentation basin, and the outlet opening is arranged in a horizontal plane in a central area of ​​the sedimentation basin.

[0015] Sludge refers to solid particles carried along in a liquid stream, e.g., suspended particles. A sludge separator, as defined in the invention, is therefore a device for separating solid particles from a liquid stream.

[0016] In this document, the boundary region of the sedimentation basin is defined as the radially outer area of ​​the sedimentation basin in a horizontal plane, in which the inlet opening is located. Starting from the geometric center of the horizontal cross-section of the sedimentation basin, the greatest horizontal extent of the sedimentation basin is determined in at least one horizontal direction. For a circular cross-section of the sedimentation basin, this greatest horizontal extent is the radius of the circular disk. In this case, the boundary region extends from 0% to 30%, and in particular from 0% to 10%, of the greatest horizontal extent towards the geometric center.

[0017] In this document, the term "central area" of the sedimentation basin refers to the central region of the sedimentation basin in a horizontal plane, in which the outlet opening is located. Starting from the geometric center of this horizontal cross-section of the sedimentation basin, the central area extends from the geometric center to 40%, and in particular 30%, of the edge of the sedimentation basin in the respective horizontal direction.

[0018] According to the invention, the end section of the inlet is understood to be the section of the inlet that substantially determines the flow direction of the liquid exiting the inlet opening. The end section is, in particular, straight. It is substantially tangential with respect to the sedimentation basin and, in particular, substantially horizontally oriented. Tangential orientation means that the flow direction at the inlet opening is essentially parallel to a tangent at the edge of the sedimentation basin.

[0019] The invention is based on the understanding that improved separation efficiency of the sludge separator can be achieved by ensuring that the liquid carrying solid particles, which is fed into the sedimentation basin, has a decreasing flow velocity within the basin, allowing the solid particles to settle. Vertical flows are to be avoided. Simulations have shown that, depending on the inlet geometry, a fluid vortex can form, which transports already sedimented material back to the upper liquid layers. Conversely, it has been observed that flows can form which carry the liquid carrying solid particles directly from the inlet to the outlet. This is disadvantageous, as no solid particles can be separated.

[0020] It was found that the tangential supply of the liquid carrying solid particles results in the formation of a peripheral, circumferential flow with decreasing flow velocity, which promotes the deposition of solid particles.

[0021] A substantially tangential and / or a substantially horizontal orientation of the end section is thus understood to mean that the end section is oriented in such a way that a circumferential flow is formed at the edge.

[0022] Furthermore, it was found that the liquid flowing tangentially into the upper edge region of the sedimentation basin, in conjunction with an upper outlet opening located in the horizontal central region of the sedimentation basin, forms a circumferential flow around the edge in the upper liquid exchange zone, resulting in a substantially flow-free zone in the horizontal central region. The geometry and arrangement of the inlet and outlet according to the invention thus advantageously ensures that the residence time of the newly supplied liquid in the sedimentation basin is sufficiently long to allow solid particles to be separated. In particular, a flow directly from the inlet opening to the outlet opening is prevented. At the same time, vertical flows, which are detrimental to the separation efficiency of the sludge separator, are suppressed.In this way, the sludge separator according to the invention can provide improved separation performance.

[0023] The inner wall of the sedimentation basin's side wall is cylindrical in shape. In a horizontal cross-section, the inner wall thus forms a circle. In this case, the tangential inflow of liquid at the outer edge of the sedimentation basin creates a slow horizontal flow in the upper liquid exchange zone, which results in a very weak vertical flow, preventing already sedimented particles from being transported upwards. Simultaneously, this leads to a long residence time of the liquid volume in the sedimentation basin, enabling particularly effective separation of solid particles.

[0024] However, according to other designs, the inner wall of the sedimentation basin can also have a different geometry. For example, it can be semicircular or rectangular.

[0025] In the sludge separator according to the invention, several lamellae are arranged in the end section of the inlet, which are in particular aligned parallel to each other.

[0026] It was found that rotation of the incoming liquid is detrimental to the separation efficiency of the sludge separator. Such rotation leads to downward-directed flow components in the sedimentation basin. However, a downward flow in the sedimentation basin also results in a counter-rotating, upward flow, which transports already sedimented solid particles back to the surface. The parallel lamellae in the inlet section of this embodiment of the sludge separator according to the invention advantageously prevent such rotation of the incoming liquid. The parallel lamellae thus prevent a vertical flow in the sedimentation basin.It was also found that such vertical currents in the sedimentation basin can be responsible for a high nitrate content on the outflow side of a conventional sludge separator, since the vertical current transported biological degradation products that had formed in the sediment upwards, where they were discharged via the outflow.

[0027] The fluid introduced via the inlet exhibits essentially no rotation due to the lamellae in the inlet's end section. The flow circulates the sedimentation basin primarily in the horizontal plane of the inlet opening and is slowed down in the process. Once the flow reaches the inlet again, the incoming fluid does indeed push the flow downwards. However, the downward component of the flow is very small throughout the entire sedimentation basin. Simulations have shown that the downward component of the flow is approximately an order of magnitude lower than the flow velocity along the main component, i.e., particularly in the tangential direction.

[0028] Furthermore, it was found that the flow created by the lamellae in the end section of the inlet, in conjunction with an outlet opening located in the central region of the sedimentation basin, is advantageous. In the central region, a virtually flow-free zone forms, partly due to the lamellae preventing the incoming liquid from rotating. The inlet and outlet geometry according to the invention thus ensures that the liquid's residence time in the sedimentation basin is sufficiently long to allow for the separation of solid particles. In this way, the sludge separator according to the invention can provide improved separation performance.

[0029] The lamellae are arranged parallel to each other and in the direction of flow of the supplied liquid in the final section. The lamellae extend in the axial direction of the final section of the inlet.

[0030] According to one embodiment of the sludge separator according to the invention, the lamellae have flat flow-guiding surfaces, the normals of which are each aligned orthogonally to the axial direction of the end section. These flow-guiding surfaces enable the lamellae to generate a self-rotating flow in the direction of the inlet opening, whereby the liquid is then directed into the sedimentation basin.

[0031] The lamellae can divide the end section, particularly in cross-section, into several separate flow channels. In cross-section, the lamellae can form adjacent flow channels. However, it is also possible for the lamellae to form a grid in cross-section, so that the flow channels then lie side by side in two dimensions. This also ensures a self-rotating inflow of the liquid into the sedimentation basin.

[0032] Preferably, the lamellae are vertically oriented. It has been found that in this case, a particularly uniform horizontal flow can be formed in the upper liquid exchange zone of the sedimentation basin, which prevents already sedimented particles from being transported upwards by vertical currents. The normals of the flow-guiding surfaces of the lamellae are therefore, in this case, particularly horizontally oriented.

[0033] The axial extent of the lamellae at the end section is greater than their cross-sectional extent at the end section. The lamellae are thus elongated in the axial direction of the end section. This effectively prevents the self-rotation of the supplied liquid.

[0034] If, in addition to the aforementioned inlet opening, the sludge separator according to the invention has one or more further inlet openings, the end section of this further inlet opening or the end sections of these further inlet openings is aligned in the same way as the end section of the one aforementioned inlet opening, i.e. the supplied liquid also flows tangentially to the side wall of the sedimentation basin via the further inlet opening or the further inlet openings.

[0035] The sludge separator according to the invention, in particular, has only the one inlet opening mentioned. Therefore, no further inlet opening is provided.

[0036] Simulation calculations have shown that, for example, tangential inlet openings that generate horizontally circulating, counter-rotating flows are disadvantageous, as a fluid vortex can form, which transports fluid volumes vertically downwards and then back upwards from the sedimentation basin. Such vertical flows can be prevented by using only one inlet opening.

[0037] According to a further development of the sludge separator according to the invention, the ratio of the total cross-sectional area of ​​the inlet to the smallest cross-sectional area of ​​the outlet is in the range of 2 to 10, particularly in the range of 4 to 8, and preferably in the range of 5 to 7. The outlet geometry thus has a smaller cross-section than the inlet geometry. This causes the liquid flow to back up in the basin. This is particularly advantageous when liquid is supplied intermittently, as, for example, in a gantry car wash. The pulsed inflow of liquid is then spread out over a longer time interval for the outflow. This increases the average residence time of the liquid in the sedimentation basin, which in turn improves the separation efficiency of the sludge separator.

[0038] The outlet opening of the sludge separator according to the invention can be oriented either downwards or upwards. An upward orientation of the outlet opening is advantageous because the portion of solid particles that still flows slightly upwards is less likely to enter the outlet opening in this case. However, a downward-oriented outlet opening can be advantageous if the outlet is to be more easily integrated into an existing sedimentation basin.

[0039] According to a further development of the sludge separator according to the invention, the outlet has an overflow opening which is arranged above the outlet opening. Particularly with an intermittent inflow of wastewater, it is important to provide an overflow opening in order to be able to discharge an excessive amount of liquid introduced into the sedimentation basin. Furthermore, the overflow opening is particularly important when the outlet cross-section is smaller than the inlet cross-section.

[0040] According to one embodiment of the sludge separator according to the invention, the outlet has a vertically oriented first outlet pipe section, in which the outlet opening is formed on one side, and which transitions on the other side into a horizontally oriented second outlet pipe section, which in turn leads into a third outlet pipe section with a larger cross-section. The third outlet pipe section can have a weir with an overflow edge and the overflow opening above the junction of the second outlet pipe section. Advantageously, this allows the overflow opening to be compactly integrated into the pipe sections of the outlet. On the outlet side behind the overflow edge, overflowing liquid can be combined with the liquid that is discharged via the outlet opening.

[0041] According to a further development of the sludge separator according to the invention, the upper liquid exchange area in the vertical direction occupies at most the upper 0% to 30%, and in particular the upper 0% to 10%, of the height of the sedimentation basin. This prevents vertically oriented currents in the sedimentation basin, which can cause sediment particles to be transported upwards towards the outlet. In this way, the separation efficiency of the sludge separator can be improved.

[0042] The sediment area, in a vertical direction, occupies, for example, at most the lower 0% to 50%, and in particular the lower 0% to 30%, of the height of the sedimentation basin.

[0043] According to one embodiment of the sludge separator according to the invention, the inlet opening is arranged above the outlet opening. The vertical distance between the inlet and outlet openings allows the sludge separator to be adapted to an intermittent inflow of liquid. However, if the inlet opening is arranged above the overflow edge, the liquid level can only rise to the overflow edge. The liquid is then discharged via the overflow opening. Furthermore, since both the inlet and outlet openings are located in the upper region of the sedimentation basin, horizontal flows are promoted. In particular, the formation of vertical eddies is prevented.

[0044] According to a further development of the sludge separator according to the invention, the inlet opening is arranged at approximately the same height as the outlet opening. The height of the inlet opening deviates, in particular, from the total height of the sedimentation basin by less than 15%, and in particular by less than 10%, from the height of the outlet opening. In this case, the inlet opening is arranged vertically in the region of the liquid level of the sedimentation basin, which, however, can fluctuate due to different inlet and outlet rates. Depending on the fill level of the sedimentation basin, the inlet opening can also be temporarily, at least partially, located above the liquid level.

[0045] According to a further development of the sludge separator according to the invention, the outlet comprises a suction line that is gas-tightly connected to the outlet opening. The suction line terminates at the outlet end in an outlet opening located below the outlet opening. The liquid level in the sedimentation basin can be defined by the suction line and the height of the outlet opening when no liquid is supplied via the inlet. The siphon effect is utilized to empty the sludge separator to a defined volume so that it can subsequently refill with a predetermined quantity of liquid. This design of the sludge separator with the suction line is particularly advantageous when an existing outlet installation in a sludge separator is replaced by the inventive outlet geometry. In this case, it may be possible to...Do not lower the height of the outlet to create the necessary volume for the incoming wastewater. With the suction line, it is sufficient to lower the height of the outlet opening to ensure that liquid is discharged down to the level of the outlet opening. This assumes that the liquid level in any collection basin located outside the sedimentation basin into which the suction line discharges is lower than the height of the outlet opening.

[0046] The suction line can also prevent a backup in the inlet if insufficient liquid can be discharged via the outlet, as at least a defined volume of liquid can be supplied without needing to be discharged. Conversely, such a backup can be prevented by the overflow opening if it is located approximately at the same level as the inlet opening.

[0047] In the sludge separator according to the invention, the following effects, achieved through the geometry of the inlet and outlet, are combined: The path taken by the flow from the inlet opening to the outlet opening is lengthened. This results in a longer residence time of the liquid in the sedimentation basin. Furthermore, it prevents the flow from impacting the inner walls of the sedimentation basin. The inner walls of the sedimentation basin are, if at all, approached at a very acute angle. Additionally, a reverse flow is reduced. This prevents the formation of rapid vertical currents, which in turn prevents sedimented particles from being carried upwards. A throttling effect in the outlet geometry causes the liquid to back up in the sedimentation basin.This increases the residence time of the liquid in the sedimentation basin, thereby improving the separation performance of the sludge separator.

[0048] The invention further relates to a vehicle wash system with a sludge separator as described above. The vehicle wash system is, in particular, a gantry wash system in which wastewater is intermittently fed to the sludge separator.

[0049] In the following, an embodiment of the sludge separator according to the invention is explained with reference to the drawings: The invention will now be explained with reference to embodiments with reference to the drawings. Figure 1 shows an embodiment of the sludge separator according to the invention in a perspective view, Figure 2 shows a vertical cross-section of the embodiment of the sludge separator according to the invention, Figure 3 shows the embodiment of the sludge separator according to the invention in a top view, Figure 4 shows the inlet of the embodiment of the sludge separator according to the invention in a first perspective view, Figure 5 shows the inlet of the embodiment of the sludge separator according to the invention in a second perspective view, Figure 6 shows the outlet of the embodiment of the sludge separator according to the invention in a first perspective view, Figure 7 shows the outlet of the embodiment of the sludge separator according to the invention in a second perspective view, and Figure 8 shows a vertical cross-section of a further embodiment of the sludge separator according to the invention.

[0050] The basic structure of the sludge separator 1 according to the invention is described below with reference to the Figures 1 to 3 The sludge separator 1 is part of a water circuit in a portal car wash. The liquid containing solid particles that is fed to the sludge separator 1 is therefore also referred to as wastewater in the following.

[0051] The sludge separator 1 comprises a cylindrical side wall 2, which is closed off at the bottom by a circular disc-shaped base 3, so that a sedimentation basin 4 is formed inside the sludge separator 1. The sludge separator 1 is closed off at the top of the cylindrical side wall 4 by a conical lid 18.

[0052] In a vertical direction, sedimentation basin 4 is divided into a lower sediment zone A, an intermediate zone B, and an upper fluid exchange zone C. The upper fluid exchange zone C, for example, occupies the upper 0% to 30%, and in particular the upper 0% to 10%, of the height of sedimentation basin 4 in a vertical direction. Sediment zone A, for example, occupies the lower 0% to 50%, and in particular the lower 0% to 30%, of the height of sedimentation basin 4 in a vertical direction.

[0053] In the upper liquid exchange area C, an inlet 5 and an outlet 7 are provided. For this purpose, a first opening 6 for the inlet 5 and a second opening 8 for the outlet 7 are arranged in the side wall 2. The inlet 5 has an inlet opening 9 through which wastewater containing solid particles can be fed into the sedimentation basin 4. The outlet 7 has an outlet opening 11 through which liquid can be discharged from the sedimentation basin 4. Further details of the inlet 5 and the outlet 7 will be explained later.

[0054] As in Figure 2As shown, the inlet opening 9 is located approximately at the same level as the outlet opening 11. In an equilibrium state for the incoming wastewater and the outgoing liquid, the inlet opening 9 is thus positioned at the level of the liquid in the sedimentation basin 4. However, both the inlet opening 9 and the outlet opening 11 are located in the upper part of the sludge separator 1, i.e., in the upper liquid exchange zone C.

[0055] As in Figure 3As shown, in a horizontal plane in which the inlet 9 and outlet 11 are arranged, a boundary region D and a central region E are formed. Starting from the center point Z of the horizontal cross-section of the sedimentation basin 4, the boundary region D extends from 0% to 30%, in particular from 0% to 10%, of the radius R towards the center point Z, and the central region E extends from the center point Z to 40%, in particular 30%, of the radius R towards the edge at the side wall 2 of the sedimentation basin 4. The radius R of the sedimentation basin 4 is 1 m.

[0056] The following will refer to the Figures 4 and 5Details of inlet 5 explained: Inlet 5 has a first inlet pipe section 5-1. This first inlet pipe section 5-1 is inserted with an opening into the first opening 6 of the side wall 2. It is horizontally oriented. A second inlet pipe section 5-2, which is vertically oriented, connects to the other end of the first inlet pipe section 5-1. A third inlet pipe section 5-3, also referred to as the end section 5-3 of inlet 5, connects to this second inlet pipe section. This end section 5-3 is oriented so that the wastewater supplied via inlet 5 flows tangentially into the sedimentation basin 4. It is also horizontally oriented. The inlet pipe sections 5-1 to 5-3 have a diameter of 150 mm. The inlet opening 9 is located in the outer edge area D of the sedimentation basin 4.The normal of the surface formed by the inlet opening 9 is tangential to the side wall 2 of the sedimentation basin 4 and horizontally oriented.

[0057] The sludge separator 1 has only one inlet opening 9 for feeding wastewater into the sedimentation basin 4.

[0058] In the end section 5-3, several lamellae 10 are arranged, aligned parallel to each other. The end section 5-3 is cylindrical, thus defining an axial direction. This axial direction is horizontal and tangential to the cylindrical side wall 2. The lamellae 10 are vertically oriented. They divide the end section 5-3 into several separate flow channels in a cross-section perpendicular to the axial direction of the end section 5-3. The lamellae 10 have planar flow-guiding surfaces whose normals are each orthogonal to the axial direction of the end section 5-3. The normals of the flow-guiding surfaces of the lamellae 10 are therefore horizontally oriented. The end section 5-3 opens into the inlet opening 9. The inlet opening 9 is subdivided into the openings formed by the flow channels created by the lamellae 10.The total surface area of ​​the inlet opening 9 has radius Rz. The normal to the surface of the inlet opening 9 is horizontally oriented and tangential to the cylindrical side wall 2.

[0059] The lamellae 10 are designed as thin, flat plates that are inserted vertically into the third inlet pipe section 5-3, their axial extent being greater than their cross-sectional extent. The lamellae 10 ensure that the incoming wastewater, which tends to rotate due to the angled arrangement of the three inlet pipe sections 5-1 to 5-3, is guided in the final section 5-3 in such a way that this rotation is lost and the wastewater enters the sedimentation basin 4 tangentially and horizontally at the inlet opening 9, thereby minimizing any vertical velocity component of the incoming wastewater.

[0060] With reference to the Figures 6 and 7 Details of drain 7 are explained below: Drain 7 has a first drain pipe section 7-1, at one end of which the drain opening 11 is formed. The first drain pipe section 7-1 is vertically oriented. The normal to the surface formed by the drain opening 11 is also vertically oriented. In the embodiment described here, the normal to the surface of the drain opening 11 points downwards. Alternatively, the normal to the surface of the drain opening 11 can also point upwards. At the other end, the first drain pipe section 7-1 transitions into a longer second drain pipe section, which is horizontally oriented. The second drain pipe section 7-2, in turn, transitions into a third drain pipe section 7-3, which has a larger cross-section. The downstream end of the third drain pipe section 7-3 is inserted into the second opening 8 of the side wall 2.

[0061] The inner diameter of the third drain pipe section 7-3 is 140 mm, the inner diameter of the drain opening 11, of the first drain pipe section 7-1 and of the second drain pipe section 7-2 is 25 mm each, and the overflow edge 13 is located 72 mm above the lower inlet of the second drain pipe section 7-2 into the third drain pipe section 7-3.

[0062] The outlet 7 is inserted into the sludge separator 1 such that the outlet opening 11 is located in the central area E of the sedimentation basin 4. Liquid is thus discharged from the center of the sedimentation basin 4 via the outlet 7.

[0063] The outlet 7 has a smaller cross-section than the inlet 5, so that the wastewater 5 can be fed in via the inlet 5 at a higher volume rate than the liquid is discharged from the sedimentation basin 4 via the outlet 7. In the described embodiment of the sludge separator 1, the ratio of the smallest cross-sectional area of ​​the inlet 5 to the smallest cross-sectional area of ​​the outlet 7 is six.

[0064] During operation of the sludge separator 1, wastewater is fed into the sedimentation basin 4, particularly intermittently, so that the liquid level in the sedimentation basin 4 rises from a minimum to a maximum level. As soon as the liquid level exceeds the highest point of the outlet 7, liquid is simultaneously discharged from the sedimentation basin 4 via the outlet 7. To prevent the liquid level in the sedimentation basin 4 from rising above a limiting level, an overflow opening 14 is provided at the outlet 7, which is located above the outlet opening 11. The overflow opening 14 is bounded at the bottom by a weir 12, which forms an overflow edge 13. The weir 12 is located at the junction of the second outlet pipe section 7-2 with the third outlet pipe section 7-3, as shown in the Figures 6 and 7 shown.

[0065] The upper fluid exchange zone C (see Figure 2) can be defined so that it extends upwards to overflow edge 13.

[0066] To set a minimum liquid level when no wastewater is supplied via inlet 5, in a further embodiment, which is described in Figure 8 As shown, a suction line 15 is provided. This suction line 15 is gas-tightly connected to the drain opening 11. The suction line 15 can, for example, be connected to the opening of the second drain pipe section 7-2 at the junction of the second drain pipe section 7-2 and the third drain pipe section 7-3 (see figure). Figure 7 ).

[0067] On the outlet side, the suction line 15 is then routed downwards outside the side wall 2, for example into a collection basin. The suction line 15 has an outlet opening 16 outside the side wall 2, which is located below the discharge opening 11. By means of the suction line 15, the liquid level in the sedimentation basin 4 can be set by the height of the discharge opening 11, independently of the highest point of the outlet 7, by means of the siphon effect, when no more wastewater is supplied via the inlet 5. This liquid level is then at the level of the discharge opening 11, provided the liquid level in a collection basin into which the outlet opening 16 discharges is below the level of the discharge opening 11. When wastewater, for example from a portal car wash, is then supplied to the sedimentation basin 4 via the inlet 5, the liquid level rises.This rise slows down when the liquid level exceeds the highest point of outlet 7, as liquid then discharges from sedimentation basin 4 via outlet 7. However, the flow rate of outlet 7 is lower than the flow rate of wastewater supplied via inlet 5 due to its smaller cross-sectional area. The rise of the liquid level is thus slowed. Should the liquid level exceed the height of overflow edge 13, liquid flows out via overflow opening 14. When the inflow of wastewater via inlet 5 ceases, the liquid level drops to the highest point of outlet 7, or, if suction line 15 is used, to the outlet opening 11.

[0068] Flow simulations were performed for the sludge separator 1 to determine the flow patterns in the sedimentation basin 4. The simulation assumed that liquid, specifically an incompressible two-phase fluid consisting of air and water, was fed in via the inlet 5 at an ambient pressure of 1.013 bar and discharged via the outlet 7. An adaptive mesh at the free water surface was used as the basis for the simulation. The unsteady simulation was performed with time steps of 0.025 s over a simulation time of 180 s. Water flowed in at a rate of 200 l / min. A flow rate of up to 12.8 l / min was established via the outlet 7, which discharged from the sedimentation basin 4. The inlet opening was located at a height of 1.67 m. Sedimented particles were found up to a height of 0.835 m above the bottom of the sedimentation basin 4.

[0069] The flow behavior in sedimentation basin 4, observed during the simulation, can be summarized as follows: The liquid level rises due to the inflow of liquid. A rotational flow is generated during the inflow. This creates a low-pressure area in the center of sedimentation basin 4, from which the outflowing liquid is discharged through the outlet opening 11. At the beginning of the inflow process, in addition to the tangential flow direction in sedimentation basin 4, there is a slight downward vertical flow direction, which decreases once the rotational flow has stabilized. After a volume of liquid has circumferentially encircled sedimentation basin 4, a slight downward flow occurs when this volume of liquid encounters incoming liquid.

[0070] Looking at horizontal cross-sections of sedimentation basin 4, there is essentially no vertical flow downwards or upwards at the mean height of the basin. Therefore, no sediment is transported upwards. Only 125 mm below the inlet opening 9 does a vertical flow component occur when the fluid flows in, and this component decreases with increasing inflow duration. Looking at a cross-section at the level of the inlet opening 9, it can be seen that a vertical flow component initially forms around the outer edge, but this decreases as soon as a horizontally circulating inflow vortex has formed. In the center, at the outlet opening 11, a low-flow area forms, which exhibits essentially no vertical flow. A vertical flow only results from the liquid that enters the first outlet pipe section 7-1 into the outlet 7 via the outlet opening 11. Reference symbol list

[0071] 1 Sludge separator 2 Cylindrical side wall 3 Bottom 4 Sedimentation basin 5 Inlet 5-1 First inlet pipe section 5-2 Second inlet pipe section 5-3 Third inlet pipe section; End section 6 First opening of the side wall 7 Outlet 7-1 First outlet pipe section 7-2 Second outlet pipe section 7-3 Third outlet pipe section 8 Second opening of the side wall 9 Inlet opening 10 Louvers 11 Outlet opening 12 Weir 13 Overflow edge 14 Overflow opening 15 Suction line 16 Outlet opening 17 Sediment 18 Conical cover A Lower sediment area B Intermediate area C Upper liquid exchange area R Radius of the sedimentation basin Z Center Rz Radius of the inlet opening

Claims

1. Sludge separator (1) having a sedimentation tank (4) that has a side wall (2) and a base (3), wherein the sedimentation tank (4) is divided in the vertical direction into a lower sedimentation region (A), an intermediate region (B) and an upper fluid exchange region (C), an inlet (5) for supplying a fluid carrying solid particles into the sedimentation tank (4), which inlet has an end section (5-3) having an inlet opening (9), wherein the inlet opening (9) is arranged in the upper fluid exchange region (C) in the vertical direction and opens into the sedimentation tank (4) in a horizontal plane in a peripheral region of the sedimentation tank (4) and wherein the end section (5-3) is orientated such that the supplied fluid flows into the sedimentation tank (4) tangentially, and an outlet (7) for discharging fluid out of the sedimentation tank (4), which outlet has an outlet opening (11) which is arranged in the upper fluid exchange region (C) in the vertical direction, wherein the outlet opening (11) is arranged in a central region of the sedimentation tank (4) in a horizontal plane, characterised in that several fins (10) are arranged in the end section (5-3) of the inlet (5).

2. Sludge separator (1) according to claim 1, characterised in that the end section (5-3) of the inlet (5) is straight.

3. Sludge separator (1) according to claim 1 or 2, characterised in that the end section (5-3) of the inlet (5) is orientated substantially tangentially in relation to the sedimentation tank (4).

4. Sludge separator (1) according to one of the preceding claims, characterised in that the end section (5-3) of the inlet (5) is orientated substantially horizontally.

5. Sludge separator (1) according to one of the preceding claims, characterised in that the fins (10) are orientated parallel to each other.

6. Sludge separator (1) according to one of the preceding claims, characterised in that the fins (10) are each arranged in the end section (5-3) in the flow direction of the fluid to be supplied.

7. Sludge separator (1) according to one of the preceding claims, characterised in that the fins (10) have even flow guiding surfaces, the normals of which are each orientated orthogonally to the axial direction of the end section (5-3).

8. Sludge separator (1) according to one of the preceding claims, characterised in that the fins (10) divide the end section (5-3) into several separate flow channels in a cross-section.

9. Sludge separator (1) according to one of the preceding claims, characterised in that the fins (10) are vertically orientated.

10. Sludge separator (1) according to one of the preceding claims, characterised in that the extension of the fins (10) in the axial direction of the end section (5-3) is larger than in a cross-sectional direction of the end section (5-3).

11. Sludge separator (1) according to one of the preceding claims, characterised in that the ratio of the smallest cross-sectional area of the inlet (5) to the smallest cross-sectional area of the outlet (7) is in a range of 2 to 10, in particular in a range of 4 to 8.

12. Sludge separator (1) according to one of the preceding claims, characterised in that the outlet (7) has an overflow opening (14) which is arranged above the outlet opening (11).

13. Sludge separator (1) according to claim 12, characterised in that the outlet (7) has a vertically orientated first outlet pipe piece (7-1) which has the outlet opening (11) formed on one side and which merges on the other side into a horizontally orientated second outlet pipe piece (7-2), which in turn opens into a third outlet pipe piece (7-3) which has a larger cross-section, and the third outlet pipe piece (7-3) has a dam (12) having an overflow edge (13) and the overflow opening (14) above the opening of the second outlet pipe piece (7-2).

14. Sludge separator (1) according to one of the preceding claims, characterised in that the outlet (7) comprises a suction hose (15) which is connected with the outlet opening (11) in a gas-tight manner and the suction hose (15) opens on the outflow side into a discharge opening (16) which is arranged underneath the outlet opening (11) and above a base of the sedimentation tank (2).

15. Vehicle washing system having a sludge separator (1) according to one of the preceding claims.