DK3150558T3 - PROCEDURE FOR CLEANING USED WASHING WATER FROM CAR WASHING INSTALLATION AND CAR WASHING INSTALLATION - Google Patents

Description

PROCESS FOR CLEANING USED WASH WATER FROM A VEHICLE WASH FACILITY AND VEHICLE WASH FACILITY

The invention relates to a process for cleaning used washing water from vehicle washing systems and a vehicle washing system with a correspondingly designed device.

In US 4,097,379 A, a self-cleaning filter device for cleaning the process water from a car wash facility is described. In this way, the process water is directed through a filter. The filter is fastened to a drum comprising holes. The process water is directed through the drum, wherein a separation of the particulate matter occurs at the filter. A filter cake is formed on the filter. A scraper is arranged tangentially to the drum such that the filter cake collecting outside of the filter is automatically removed due to the regular rotation of the drum. DE 195 00 131 A1 discloses a system for cleaning used washing water from vehicle washing systems. For particle separation, the system has as its cleaning device a not further defined centrifuge.

From US 2004/192980 A1, a process is known in which waste products with low caloric value are converted into useful, more high-energy products, such as for example gas, oil and solid carbon. To separate small solids which are dissolved in water, a centrifuge is used in the process. The drum of the centrifuge has small perforations which are used to separate the particles. A process for preparing process water from a car wash facility is also disclosed in WO 01/21537 A1. A centrifuge is used in this respect as a separator in order to separate oil and solids from water. FR 2981926 A1 discloses a process for cleaning process water from a car wash facility. To separate solids, a centrifuge is used, which acts in a similar manner to a centrifugal pump. Within the separating chamber, a rotating drum is arranged in the centre. The drum is only used for the transfer of energy to the fluid. The denser solids to be separated are pressed to the outer wall of the separating chamber and can be removed therefrom.

In washing facilities for vehicles, particularly car washes, which are driven through continually and for which a significantly larger water volume is circulated, large quantities of dirt particles arise in the respective washing areas, which are made up of coarse particles, such as sand for example, and from finer particles, which, for example, consist of deposited dust, grit and similar.

To save fresh water and put as little strain on the public wastewater system as possible, it has been accepted for some time to treat and reuse the wastewater or process water from vehicle washing systems. To do this, the particles of dirt contained in the process water must be removed as far as possible so that only a very small amount of dirt particles remains in the treated process water. Larger particles of dirt could cause scratches in the paint surface in washing facilities that work using rotating brushes or rotating cloths and have an abrasive effect similar to that of scouring grit. A breakdown of the treatment technology leads to higher operating costs for the vehicle washing system and can, in the worst case, require a shutdown of the washing facility.

To separate particles from the washing water of vehicle washing systems, mechanical separating equipment is commonly used, wherein particles are separated from process water for example using filters, sieve drums or centrifuges. To separate sludge into a solid and liquid fraction, centrifugally operated filters are used. One centrifugal filter embodiment is the so-called basket centrifuge, which consists of a perforated, cylindrical container which rotates about a vertical axis. The inner surface of the container is fitted with a replaceable filter cloth in which the solids are retained, whereas the liquid is driven through the cloth due to the centrifugal force. The working method is batch-wise, i.e., the supplied suspension must be periodically interrupted in order to facilitate the removal of the solids, which have collected on the filter cloth, by means of a scraping blade or the like. Alternatively, a backwashing of the centrifuge is possible to remove a formed filter cake. The operation of basket centrifuges has disadvantages due to the batch-wise method of working and due to limitations relating to the removal of the formed filter cake. Design possibilities to continually remove the solids from such separating equipment and therefore facilitate continual operation are laborious and prone to failure, which can lead to breakdowns in the process water cleaning and cause higher equipment costs, particularly for large quantities of process water requiring cleaning, as tends to be the case with vehicle washing systems.

The object of the present invention is to provide a process for cleaning used washing water from vehicle washing systems and a vehicle washing system with a device for cleaning washing water, with which a continual treatment of washing water is cost-effectively feasible and the use of which largely facilitates failure-free operation of the vehicle washing system irrespective of the workload.

The above object is achieved by a method with the characteristics of claim 1 and by a device with the characteristics of claim 6. Advantageous embodiments of the invention are the subject matter of the dependent claims.

According to the invention, a process for cleaning used washing water from vehicle washing systems by means of particle separation is proposed, wherein a cleaning device for process water is provided which has at least one drum being rotatably mounted in a housing, at least one process water inlet discharging into the housing outside the drum, at least one process water drain discharging from the drum, at least one housing outlet arranged outside the drum for particle removal from the housing and a rotary drive for the drum. The drum has a plurality of openings, wherein the rotational speed of the drum and the pressure level of the housing are adjusted by means of the particle-rich process water supplied under excess pressure via the process water inlet such that process water enters the drum through the openings and particles are prevented from entering the drum via the openings due to the rotation of the drum with multiple g-force. Due to the rotation of the drum, g-forces of at least 300 g act on the particles. By means of the rotation of the drum, a particle-free zone is preferably formed in the near-field range of the drum, wherein the near-field range can have a width of at least 0.5 mm, preferably at least 1 cm, more preferably of at least 2 cm. In the near-field range, no separable particles are then substantially contained due to the g-forces acting on the particles, which depends among other things on the rotational speed of the drum and the pressure level of the particle-rich process water supplied under excess pressure.

The process according to the invention provides that particulate-containing process water is supplied under excess pressure of a centrifugally-operated rotating drum and enters the drum unobstructed through openings of the drum, wherein particles are prevented from entering the drum via the openings due to the rotation of the drum.

The washing facility according to the invention has a device designed for washing water treatment with at least one drum being rotatably mounted in a housing, at least one process water inlet discharging into the housing outside the drum, at least one process water drain discharging from the drum, at least one housing outlet arranged outside the drum for particle removal from the housing and a rotary drive for the drum. The drum has a plurality of openings, wherein the rotational speed of the drum and the pressure level of the particle-rich process water supplied via the process water inlet can be adjusted such that the process water enters the drum through the openings, while particles are prevented from entering the drum through the openings due to the rotation of the drum with multiple g-force.

With the solution according to the invention, the drum is centrifugally-operated, i.e., high g-forces act on particles in the process water preventing the particles from entering the drum with the process water via the openings of the drum and being removed from the drum via the process water drain. Instead, particle enrichment in the process water outside the drum occurs, wherein the particle removal occurs via the housing outlet, preferably with a certain amount of process water enriched with the particles. In this context, it can be provided that less than 10% of the supplied process water, preferably less than 5% of the process water, is removed with the particles via the housing outlet. On the other hand, the particle-poorer process water arising in the openings of the drum is drained from the drum and therefore from the housing via the process water drain.

The process according to the invention and the device according to the invention facilitate a cost-effective and efficient cleaning of used washing water from vehicle washing systems, wherein a continual method of working is possible at the same time as a simply designed embodiment of the device according to the invention. The device according to the invention is characterised due to the simple design by a low failure susceptibility and high component stability even with large particle quantities in the process water, which leads to a high operational safety of the cleaning process according to the invention. The simply designed structure of the device leads to lower manufacturing costs and allows economic operation of the water cleaning even with redundant processing with several parallel- or series-connected devices according to the invention. By means of parallel connection of the devices according to the invention, even large quantities of process water can be cleaned. The removal of particles can occur in a purely mechanical manner, i.e., free of auxiliary materials such as flocculation aids. However, the use of auxiliary materials is not definitively excluded.

The openings in the drum act only as through-flow openings for the process water. The opening width of the openings is therefore sufficiently dimensioned, wherein particles are not retained in the drum due to the particle size. A filter sieve or filter medium sealing the openings is not provided. As a result, no filter cake is formed on the outside of the drum either. The through-flow openings of the drum have in this context a minimum opening width of greater than 2 mm, particularly of greater than 5 mm. Expressed in other words, this means that the opening width of the drum openings is considerably greater than the particle size of the particles contained in the process water that are to be removed. As no filter cake forms on the outside of the drum, in comparison with the basket centrifuges known from the prior art, which require separation tools such as scraper blades or similar to separate the filter cake, a considerably simpler constructive design of the device according to the invention is produced. The device according to the invention is therefore also less prone to failure.

To achieve a sufficiently high separation output for particles, the rotational speed of the drum is preferably selected such that acceleration forces or centrifugal forces between 300 g and 1,000 g, more preferably of approx. 500 g, are exerted on the particles. The g-forces can also be greater than 1000 g with a correspondingly higher rotational speed of the drum. The connection between the rotational speed of the drum and the level of g-force being effected on the particles can be determined in this context approximately on the basis of the following equation (I): g-force = 1.118 10'5 r rpm2 (I) with r = rotational radius of the drum in [cm] rpm = rotational speed of the drum in [U/min]

For a sufficiently good separation output, the rotational speed of the drum is preferably in the range between 1000 U/min and 3000 U/min, further preferably between 1500 U/min and 2000 U/min, particularly preferably around 1500 U/min.

To ensure that the process water can enter the drum despite the centrifugal force, the process water is supplied into the housing with an absolute pressure between 3 bar and 10 bar, further preferably between 4 bar and 6 bar, particularly preferably of around 5 bar. The process water supply to the housing occurs by means of a pump, wherein the pressure drop between the process water entry into the housing and the process water outlet from the drum can preferably amount to less than 1 bar, particularly less than 0.5 bar. The device according to the invention is suitable for separating particles up to a size of 100 pm, preferably of 10 pm, more preferably of 1 pm, from the process water. Accordingly, the maximum particle size in the process water drained from the drum via the process water drain can be less than 100 pm, preferably less than 10 pm, particularly preferably less than 1 pm. A particle pre-separator, particularly a sieve filter, can be connected upstream of the process water inlet. Accordingly, the maximum particle size in the process water supplied to the housing can be less than 1 mm, preferably less than 600 pm, more preferably less than 400 pm (separation cut).

The device according to the invention is suitable due to the constructive embodiment for water cleaning of process water volume flows in the scale between 1 m3/h to 10 m3/h, preferably between 5 m3/h to 8 m3/h, more preferably of approx. 7.5 m3/h. Higher process water volume flows can be achieved with redundant processing with a plurality of parallel-operated separating devices according to the invention.

An outer casing of the drum can be formed by a perforated metal plate, wire mesh, metal grating or coiled metal bars. The outer casing can together with a drum base and a drum lid form a cylindrical rotational body into which the process water can enter unhindered via the drum openings. It is essential that the drum openings in the outer casing have a sufficiently large opening width in order to prevent the formation of a filter cake on the outside of the drum.

In the housing, at least one preferably trough-shaped recess can be provided to extend the radius of the housing and as a particle collector. In particular, the recess can be formed as a collecting channel, wherein particles migrate outwardly in the radial direction due to the centrifugal forces and a concentration of particles on the inner edge of the housing and particularly in the region of the recess occurs. The housing can have a cylindrical outer wall, wherein the channel bottom of the collecting channel is then located in the outermost position in the radial direction, such that the largest particle concentration occurs in the region of the collecting channel. The collecting channel can preferably extend parallel to the rotational axis of the drum, but can also run obliquely to the rotational axis. At least two oppositely arranged collecting channels can preferably be provided. To remove the particles from the region of the recess, a housing outlet can discharge in the region of the recess, wherein the housing outlet is provided particularly in the housing base.

With a further preferable embodiment, the drum can be driven via a shaft. The drainage of process water from the drum can occur via a hollow shaft, wherein the hollow shaft can have openings in the interior of the drum, via which the process water enters the hollow shaft from the drum and is then drained from the drum via the hollow shaft.

In principle, the rotational axis of the drum can run to be perpendicular to the base or at an arbitrary inclination to the base. In a preferred embodiment of the invention, the rotational axis of the drum is however situated in a horizontal plane, such that the drum is located in a recumbent position. Irrespective of whether the drum is arranged in an upright or recumbent position, i.e., irrespective of whether the rotational axis runs vertical to the base or is located in a horizontal plane, the process water supply occurs into the housing incorporating the drum and the process water outlet from the housing and the particle removal from the housing each occurs preferably via the outer partitioning walls of the housing arranged to be perpendicular to the rotational axis of the drum.

The above description and further details, characteristics and advantages of the present invention result by reference to the following description of a preferred embodiment of a device according to the invention, which should not be considered as limiting, in conjunction with the attached drawings, in which

Fig. 1 shows a schematic cross-sectional view of a device for cleaning washing water by means of particle separation in a vehicle washing system according to the invention,

Fig. 2 shows a perspective view of a drum used for particle separation in the device from Fig. 1 and

Fig. 3 shows a perspective view of the housing of the device from Fig. 1

In Fig. 1, a device 1 for cleaning used washing water or process water 2 in vehicle washing systems by means of particle separation is shown. The device 1 has a housing 3 that is formed by a housing base 4, a housing lid 5 and a housing casing 6. The housing 3 stands on a substrate by means of supporting feet 7.

In the housing 3, a drum 8 is arranged which is non-rotatably connected with a hollow shaft 9. By means of a motor 10, the hollow shaft 9 and the drum 8 can be displaced in a rotational movement about the rotational axis X. The drum 8 is formed by a closed drum base 11, a perforated drum casing 12 and a closed drum lid 13. The hollow shaft 9 is rotatably mounted on the housing 3 by means of two bearings 14, 15 and connected with the motor 10 by means of a coupling 16.

Outside the drum 8, a feed line 17 discharges into the housing 3, via which particle-rich process water 2 is supplied into an interior 18 of the housing 3. The process water inlet occurs via the housing lid 5 being displaced outwardly in the radial direction opposite the drum casing 12.

In the housing base 4, a number of outlet openings are provided, which facilitate a particle removal from the housing 3 by means of outlet lines 19, 20, 21. Herein the outlet openings 19, 20 are connected with an outlet line 22. While not shown in Fig. 1, the outlet line 21 positioned in the outwardly right radial position can also be connected with the outlet line 20. Equally, it is possible that further outlet openings (not shown) are provided in the housing base 4 in order to facilitate particle removal from the housing 3. The outlet openings 19, 20, 21 are preferably arranged as far outwardly as possible in the radial direction, as the concentration of particles arises in this area during the water cleaning.

The particle separation from the process water 2 occurs as described below. The particle-rich process water 2 is introduced into the housing 3 with a defined overpressure (absolute pressure) of, for example, 5 bar in the interior 18 of the housing 3 and therefore outside the drum 8. To adjust the relevant pressure level of the process water 2, a pump, not shown in Fig. 1, is provided. For the particle separation, the hollow shaft 9 and therefore the drum 8 is brought into a rotational movement with the rotary drive 10, wherein the rotational speed of the drum 8 is for example at approx. 1500 U/min. Due to the rotation of the drum 8, very high g-forces are effected on the particles in the process water 2, which lead to the particles being pushed outwardly in the radial direction. The particle concentration in the process water 2 increases outside the drum 8 in the radial direction to the interior of the housing casing 6. This is shown schematically by arrow 22 in Fig. 1. The housing casing 6 can preferably be formed cylindrically.

Through the movement of the particles outward in the radial direction, a particle enrichment in the process water 2 near the drum 8 occurs such that particle-poorer process water 2 enters the drum 8 via the openings 23 in the drum casing 12. The openings 23 are outwardly free and not overlaid or underlaid by a filter medium. From here, the process water 2 enters the hollow shaft 9 via the openings 24 of the hollow shaft 9 and is outwardly discharged by the hollow shaft 9. Due to the opening width of the openings 23 in the drum casing 12, which is considerably larger than the diameter of the particles in the process water 2, it is ensured that a filter cake is not formed on the outside of the drum 8 during the process water entry into the drum casing 8. The openings 23 in the drum casing 12 can in this context have a diameter of 5 mm or more.

The separation stage during the particle separation can be with a particle size of less than 100 pm, preferably less than 10 pm, more preferably less than 1 pm. Moreover, it is not shown that there can be a particle pre-separator connected upstream of the device 1 to ensure that the maximum particle size in the particle-rich process water 2 supplied to the housing 3 is less than 1 mm, preferably less than 600 pm, more preferably less than 400 pm. With the device 1, process water volume flows of preferably 1 m3/h to 10 m3/h can be cleaned.

The particle removal occurs by means of the outlet openings connected with the outlet lines 19, 20 and 21 in the region of the housing base 4. Preferably, the particle removal occurs together with a specific quantity of process water 2, such that a concentrated particle flow 25 is discharged. In this context, preferably less than 10 wt.%, particularly less than 5 wt.%, of the uncleaned process water 2 supplied via the inlet pipe 17 can be discharged together with the particles via the outlet lines 19, 20 and 21. The volume flows can be adjusted and controlled via outlet valves that are not shown here. The particle flow 25 can be supplied to a further water treatment process.

The housing 3 and the drum 8 and all components of the device 1 coming into contact with the process water 2 are made preferably from stainless steel.

Figure 2 schematically shows the drum 8. The drum casing 12 is formed in the depicted embodiment by a perforated metal plate, which is perforated over the entire peripheral surface. The openings 23 can have a diameter of 5 mm or more.

Fig. 3 shows the housing casing 6 of the housing 3 in a perspective view. The housing casing 6 has a cylindrical wall section 26, which has two flange sections 27, 28 for connection with the housing base 4 and the housing lid 5. Moreover, collecting channels 29 are provided on opposite sides of the wall section 26. The collecting channels 29 act as particle collectors, which extend parallel to the rotational axis X of the drum 8. In the region of the collecting channels 29, the radius of the wall section 26 is expanded, wherein a channel base 30 of the respective collecting channel 29 is located in the outermost position in the radial direction. The largest particle concentration occurs in the region of the collecting channels 29 during the particle separation. It is therefore provided that the outlet openings connected with the outlet lines 19, 21 (Fig. 1) should be arranged in the container base 4 in the radial direction below the collecting channels 29. The particle removal from the region of the collecting channels 29 then occurs via the outlet lines 19, 21.

Figures 1 to 3 show the device 1 with an upright arrangement of the drum 8. In this respect, the rotational axis X runs vertical to the base. However, an embodiment can be preferred, with which the drum 8 is located in the recumbent position, wherein the drum 8 then rotates about a horizontal rotational axis X. In both embodiments, the process water supply into the housing 3 or the process water outlet and particle removal from the housing 3 occur respectively via the outer partitioning walls of the housing 3, which are arranged to be perpendicular to the rotational axis X. With an upright arrangement of the device 1, the process water inlet thereby occurs via the housing lid 5 and the process water drain and particle removal via the housing base 4. With a recumbent arrangement of the drum 8, the process water supply into the housing 3 sor the process water outlet from the housing 3 and, preferably, the particle removal occur via the outer lateral partitioning walls of the housing 3. Process water supply and outlet and particle removal thereby preferably occur parallel to the rotational axis X in the axial direction. However, in principle, it is also possible that the process water supply and/or process water outlet and/or particle removal into or from the housing 3 occurs via the radial outer surface of the housing 3 or the housing casing 6, and thereby transverse to the rotational axis X of the drum 8.

It is also not shown that the housing 3 can have at least one ventilation opening and/or ventilation line in order to ventilate the interior of the housing 3. The ventilation can preferably occur via the container lid 5 and/or the container base 4. Ventilation via the outer surface of the housing 3 is also possible in principle.

Reference numeral list: 1 Device 2 Process water 3 Housing 4 Housing base 5 Housing lid 6 Housing casing 7 Supporting foot 8 Drum 9 Hollow shaft 10 Rotary drive 11 Drum base 12 Drum casing 13 Drum lid 14 Bearing 15 Bearing 16 Coupling 17 Supply line 18 Interior 19 Outlet line 20 Outlet line 21 Outlet line 22 Arrow 23 Opening 24 Opening 25 Particle flow 26 Wall section 27 Flange section 28 Flange section 29 Collecting channel 30 Channel base

Claims (9)

PROCEDURE FOR CLEANING USED WASHING WATER FROM CAR WASHING INSTALLATION AND CAR WASHING INSTALLATION A method of purifying used wash water (2) from car wash systems by particle separation with an industrial water purifier (1), wherein the purifier (1) comprises at least one drum (8) pivotally disposed in a housing ( (3) at least one industrial water outlet leading into the housing (3) outside the drum (8), at least one industrial water drain leading away from the drum (8), at least one housing outlet located outside the drum (8); a particle discharge from the housing (3) and a rotating drive (10) to the drum (8), the drum (8) having a plurality of apertures (23), the rpm of the drum (8) and the pressure level of the particulate rich water (2) which the housing (3) is supplied under pressure via the industrial water inlet, adjusted in such a way that the industrial water (2) flows through the openings (23) into the drum (8) and particles due to the rotation of the drum (8) with multiple g-force are prevented in reaching the drum (8) via the openings (23), where g-forces of at least 300 g acts on the particles due to the rotation of the drum (8), where the industrial water (2) is supplied to the housing (3) with an absolute pressure of between 3 bar and 10 bar, and where the minimum opening width of the openings (23) in the drum (8) is greater than 2 mm. Method (1) according to claim 1, characterized in that, due to the rotation of the drum (8), g-forces of between 300 g and 1000 g, preferably of approx. 500 g which affects the particles. Method (1) according to one of the preceding claims, characterized in that the speed of the drum (8) is set to a value between 1000 rpm and 3000 rpm, preferably between 1500 rpm and 2000 rpm. , more preferably at approx. 1500 rpm Method (1) according to one of the preceding claims, characterized in that the industrial water (2) is supplied to the housing (3) with an absolute pressure of between 3 bar and 10 bar, preferably between 4 bar and 6 bar, especially of approx. . 5 bar. Process (1) according to one of the preceding claims, characterized in that a particle separation is provided by adjusting the speed of the drum (8) and the pressure level in the particle-rich industrial water (2) supplied to the housing (3) via the industrial water flow. up to a size of 100 µm, preferably 10 µm, more preferably 1 µm, from the industrial water (2). A car wash system with a device (1) for the purification of spent washing water from the car wash system, the device (1) comprising at least one drum (8) pivotally arranged in a housing (3), at least one industrial water outlet leading to the housing (3) outside the drum (8), at least one industrial water drain leading away from the drum (8), at least one housing outlet located outside the drum (8), for particle discharge from the housing (3) and a rotating drive (10) ) to the drum (8), wherein the drum (8) has a plurality of apertures (23) and where the speed of the drum (8) and the pressure level in the particulate rich water (2) supplied to the housing (3) under pressure through the industrial water supply can be is adjusted in such a way that the industrial water (2) flows through the openings (23) into the drum (8) and particles due to the rotation of the drum (8) with multiple g-force are prevented from entering the drum (8) via the openings (23), where g-forces of at least 300 g act on the particles due to the root of the drum (8) where the industrial water (2) can be supplied to the housing (3) with an absolute pressure of between 3 bar and 10 bar, and where the minimum opening width of the openings (23) in the drum (8) is greater than 2 mm. Car wash system (1) according to claim 6, characterized in that a drum sheath (12) is formed on the drum (8) by means of a hole plate, a wire mesh, a metal grating or metal rod. Car wash system (1) according to one of the preceding claims 6 or 7, characterized in that at least one preferably gutter-shaped recess for radius expansion and as a particle collector is provided in the housing (3). Car wash system (1) according to one of the preceding claims 6 to 8, characterized in that the drum (8) is connected rotationally to a hollow shaft (9), the discharge of industrial water (2) from the drum (8) taking place via the hollow shaft (8). 9).