System for filtering fluids

Abstract

1. System 2. A system for filtering fluids, at least consisting of a primary filter (10), which has at least one filter element (12) which can be flowed through in one direction for a filtration process and in the opposite direction for a back-flushing process, and with a secondary filter (44) which has at least one further filter element (48), characterised in that some of an infiltrate flow awaiting filtration in the primary filter (10) is forwarded for a filtration through the secondary filter (44) to said secondary filter, and that back-flushing fluid produced during the back-flushing with the primary filter (10) goes past the secondary filter (44) to a clean side (66) at which the secondary filter (44) discharges its filtrate amount.

Description

[0001] SYSTEM FOR FILTRATION OF FLUIDS

[0002] The invention relates to a system for filtering fluids, at least consisting of a primary filter having at least one filter element through which flow can pass in one direction for a filtration process and in the opposite direction for a backwash process, and with a secondary filter having at least one further filter element.

[0003] EP 3 265 202 B1 discloses a system for filtering fluids, comprising a primary filter having at least one filter element through which fluid can flow in one direction during the filtration process and in the opposite direction for a backwash process, a post-treatment device arranged downstream of the primary filter for processing the backwash quantities released by the filter, which post-treatment device has at least one filter chamber receiving the backwash quantities, with a fluid inlet and fluid outlet, and with at least one post-treatment filter element, and a control device for feeding the respective backwash quantity in portions to the assignable post-treatment filter element, wherein the control device has a control chamber with a first and a second fluid chamber,The first of which serves to accommodate the respective backwash volume, and the second fluid chamber can be pressurized with a compressed gas at a predefined working pressure, and the first and second fluid chambers of the control chamber are separated by a separating piston. In this way, a more or less continuous cleaning of the backwash volumes generated in the primary filter during backwashing can be achieved. A compressed gas, particularly in the form of compressed air, is used to operate the system. This generally requires a certain amount of technical effort, which has a negative impact on the costs both during the acquisition and operation of the system. Since such systems are regularly used in the filtration of heavy fuel oils, for example, in the operation of large diesel engines, such as marine diesel engines, the required compressed gas or compressed air is not always available directly at the filtration site.

[0004] Based on this prior art, the invention seeks to create a system for filtering fluids that is functionally reliable and cost-effective in both purchase and operation. This object is achieved by a system having the features of patent claim 1 in its entirety.

[0005] Because, according to the characterizing part of patent claim 1, part of an unfiltered stream awaiting filtration in the primary filter is passed on to the secondary filter for filtration and because the backwash fluid generated during backwashing with the primary filter passes past the secondary filter to a clean side to which the secondary filter releases its filtrate quantity, improved filtration of a fluid stream, such as a lubricating oil stream, is achieved in a cost-effective manner without the use of additional auxiliary media, such as compressed gas.

[0006] With the system solution according to the invention, filtration of the main flow is achieved by means of a primary filter, preferably in the form of an automatic backwash filter, with additional continuous lubricating oil treatment in the bypass flow to the main flow, using a correspondingly designed secondary filter. This secondary filter is thus installed in the bypass flow to the main flow, and accordingly, only a predeterminable small portion of the lubricating oil supplied by individual main lubricating oil pumps is passed through this filter to perform a type of lubricating oil treatment.

[0007] As already explained, an automatic backwash filter is used for the primary filter, which filters in the main flow during continuous backwashing, whereby the secondary filter in the bypass flow is continuously supplied with unfiltered material from the primary filter for a filtration process, so that continuous fluid cleaning is achieved with both filters in both the main flow and the bypass flow.

[0008] Preferably, it is further provided that the secondary filter has a higher filter fineness than the primary filter, which benefits the desired quality of the lubricating oil care.

[0009] Furthermore, it is provided that an unfiltered water chamber of the primary filter is fluidically connected to an unfiltered water chamber of the secondary filter via a connecting line. Preferably, the connecting line between the two filters runs along the bottom and can be shut off by means of a shut-off device. This allows the two filters to be separated from each other, for example, to replace used filter elements with new ones.

[0010] In a preferred embodiment of the system according to the invention, it is provided that the respective filter element of the secondary filter is flowed through from outside to inside during filtration and the primary filter from inside to outside. And that for backwashing of the respective filter element of the primary filter, the latter is flowed through in the opposite direction from outside to inside. In particular, the secondary filter can consist of several filter layers and thus offers a very large filter surface so that, in conjunction with the special folding or pleating technology for the element material, the secondary element overall achieves a very high dirt holding capacity compared to the primary filter, which in turn can be continuously cleaned of dirt by means of the backwash device, which is not provided for the secondary filter.

[0011] Preferably, a throttle is provided on the discharge side of the secondary filter to throttle the associated filtrate flow. The desired continuous lubricating oil flow is regulated in terms of quantity via the throttle, which can also be an orifice plate. If the throttle is set to a predeterminable free cross-section, a clearly defined pressure is generated behind its opening as seen in the direction of fluid flow. This pressure remains constant even if the system pressure increases, and the lubricating oil flow passing through the orifice plate in the secondary filter is limited in a defined manner. In this way, despite the continuous filtration in the main flow via the primary filter, all of the circulating lubricating oil can pass through the secondary filter element, designed as a fine filtration stage, for example twice every 24 hours. This then leads overall to very effective lubricating oil maintenance.

[0012] In a further preferred embodiment of the system according to the invention, it is provided that a backwash device of the primary filter releases the backwash volume generated during backwashing at the same time as filtration to the clean side via a separate backwash line. This backwash volume can optionally also be subjected to filtration, as shown by way of example in the prior art EP 3 265 202 B1 mentioned above. In a further preferred embodiment of the system according to the invention, it is provided that the primary filter and the secondary filter, combined on a carrier device, form a manageable structural unit, and that the connecting line and the backwash line, preferably running at least partially parallel to one another, converge at a common connection point to which a discharge line of the clean side is connected.This makes the system very easy to handle and install on-site, for example, in the area of ​​marine diesel engines on board ships. The system then requires only three standard flanges—namely, for the inlet, the outlet, and the tank return line as the clean side—to connect to an overall supply circuit for the lube oil supply to the consumer, such as a marine diesel engine. This has no equivalent in the state of the art.

[0013] The subject of the system solution according to the invention is also its use in the context of a continuous lubricating oil cleaning for a consumer, such as an internal combustion engine, in the main flow, a part of which is branched off and passed past the consumer, for the realization of lubricating oil care in the secondary flow is additionally cleaned, preferably using a very fine cartridge element in the form of the secondary filter.

[0014] The system according to the invention is explained in more detail below using an exemplary embodiment as shown in the drawing. The drawings are schematic and not to scale.

[0015] Figure in the form of a sectional view of the essential components of the system in a front view;

[0016] Figure 2 is a rear view of the system according to Figure 1, also in longitudinal section; and Figure 3 is a hydraulic circuit diagram showing the use of the system according to Figures 1 and 2 in a lubricating oil supply circuit for a consumer, such as an internal combustion engine.

[0017] Figure 1 shows a system for filtering fluids as a whole. The system comprises a primary filter 10 having a fluid-permeable filter element 12 inside. The medium to be filtered, here in the form of lubricating oil, enters the filter container 16 via a filter inlet 14 and, starting from the lower filter inlet 14, rises upwards via the interior 18 of the filter container 16 as viewed in the direction of Figures 1 and 2, before flowing through the basket-shaped filter element 12 from the inside out. The fluid, which has thus been regularly cleaned of particle contamination, then leaves the filter in the main flow via the filter outlet 20 located spatially above the filter inlet 14. As it flows through the filter element 12 from the inside out, particles (not shown) are deposited on the inside of the filter element 12 during the filtration process.During the filtration of the main flow, a flushing arm 22 rotates continuously around the vertical or longitudinal axis of the primary filter 10 and any dirt particles adhering to the inside of the filter element 12 are then led out of the primary filter 10 via a backwash line 24.

[0018] Automatic backwashing with the flushing arm 22 can be performed continuously as follows. A hydraulic drive 26 arranged on top of the primary filter 10 rotates the flushing arm 22 as a whole over the individual segments of the filter element 12 that are to be cleaned and of which this filter element 12 consists. Due to the resulting pressure drop between the filter outlet 20 and the backwash line 24, the cleaning of individual segments is carried out in countercurrent. The segments of the filter element 12 that are not passed over by the flushing arm 22 with its respective cleaning sections, however, remain in continuous filtration mode for the main flow to ensure its uninterrupted filtration.The continuous backwash prevents a drop in operating pressure in the primary filter 10, and the aforementioned segmentation of the filter element 12 as a whole ensures highly effective cleaning of the filtration mesh with a very low flushing volume during operation. The rotation function of the flushing arm 22 is monitored using a suitable sensor 28 on the hydraulic motor 26, which can be electronically evaluated via appropriate evaluation electronics (not shown).

[0019] The individual annular segments of the filter element 12 are cleaned together, one after the other and continuously without interruption, across their entire installation height by means of the flushing arm 22. The rotary drive for the flushing arm 22 can be either hydraulic or electric, as already explained. A hydraulic drive via the hydraulic motor 26 is optimized in such a way that it begins operation even at low operating pressure. Furthermore, the hydraulic motor 26 used is characterized by a low displacement, which increases the performance of the motor 26. The hydraulic motor 26 is preferably driven by the pressure in the associated oil lubrication circuit.

[0020] As can be seen particularly from the rear view of the primary filter 10 according to Figure 2, the flushing arm 22 is provided along its longitudinal axis with a chamber recess 30 into which the respective backwash fluid enters from the filter element 12, wherein the backwash quantity is permanently discharged from the chamber volume 30 into the backwash line 24 via a lower passage opening 32 (as viewed in the direction of Figure 2). The backwash line 24 is connected to a cavity 34 of a bearing receptacle 36, which is preferably the bottom part of the filter housing or filter container 16. In the bearing receptacle 36, which is stationary in the filter container 16 and projects upwards, the plate-shaped flushing arm 22 is rotatably mounted on the base or bottom side, wherein the head side of the flushing arm 22 is operatively connected to the hydraulic motor 26 via a coupling 38.The chamber recess 30 extends in a slit-like manner through the flushing arm 22 and, optionally divided into segments, has nozzle-shaped openings on the free end facing the inside of the filter element 12 for the passage of the backwash fluid from the filter element 12. The backwash fluid arriving in the chamber recess 30 is then guided via the passage opening 32 and a through opening in the bearing receptacle 36 with a bearing for the flushing arm 22 into the cavity 34 and from there fed into one free end of the backwash line 24, which opens into the cavity 34. In this respect, the cavity 34 and one end piece of the connected backwash line 24 are rigidly arranged in the stationary filter container 16.

[0021] The automatic backwash filter or primary filter 10 can be equipped with individual bypass valves 40 above the basket-like filter element 12. These bypass valves are only indicated in the drawings in Figures 1 and 2 and are intended for emergency operation if a malfunction occurs in the automatic cleaning process. Thus, if a predefined differential pressure of, for example, 2 bar is exceeded, the individual bypass valves 40 can open and allow flow through a safety filter stage built into the respective valve 40, with the result that the primary filter 10 is then in emergency operation. Before such emergency operation occurs, a differential pressure monitor 42 can trigger an alarm and inform the operator that the system or installation has a possible problem that requires maintenance or repair.

[0022] Such backwash filters are offered and sold on the market by the property rights holder under the brand name "AutoF i lt®RF 15". Details of this automatic backwash filter can be found in a brochure of the property rights holder with the publication number DE 7.823.1 / 08.22. Other backwash filters suitable for the system are disclosed in WO 2012 / 15001 1 A1, WO 2018 / 068887 A1 and WO 2018 / 068888 A1.

[0023] Furthermore, in addition to the primary filter 10, the system comprises a secondary filter 44, which has a further filter element 48 in a filter housing 46, the element material 50 of which extends between an upper end cap 52 and a lower end cap 54 and is folded or pleated (not shown) to increase the effective filtration area. Since the element material 50 of the filter element 48 is flowed through from the outside to the inside, a fluid-permeable support tube 56 can be provided on the inside of the element material 50 in the usual way. This support tube stiffens the filter element 48 as a whole and provides support for the filter pleats during filtration operation with the secondary filter 44.The filter housing 46 of the secondary filter 44 comprises the filter element 48 with a predeterminable radial distance, wherein base-side housing parts 58 of the filter housing 46 in the area of ​​the inlet of the unfiltered flow are expanded in diameter compared to the rest of the filter housing 46, so that a type of swirl flow can be established over the height of the entire filter element 48, which helps to improve the flow and thus the filtration performance for the secondary filter 44.

[0024] The upper end cap 52 of the filter element 48 rests on a receiving part 60 on the inside of the upper part of the filter housing 46, whereas the lower end cap is pushed or placed onto an element receptacle 62, which is part of a fluid guide 64 that guides the filtrate side of the secondary filter 44 to a clean side 66 of the system. A throttle 68 with a predeterminable free cross-section is connected between the clean side 66 and the tubular fluid guide 64. The filtrate or lubricating oil flow generated by the secondary filter 44 can be specified via the throttle 68. While for the element material of the filter element 12 of the primary filter 10, for example, a fabric with a passage width > 34 / m is used with a predeterminable separation efficiency of 50% of the particles, a filter fineness of, for example, 1 to 10 / jm is provided for the element material 50 of the filter element 48 of the secondary filter 44.In this way, the secondary filter 44 forms a microfilter, in the manner of a cartridge element or a filter cartridge.

[0025] As can be seen in particular from Figure 1, the unfiltrate stream entering via the filter inlet 14 enters the filter container 16, in particular initially onto its bottom side. Starting from this bottom side of the filter container 16, a connecting line 70 opens with one free end into the interior 18 of the filter container 16 and with its other opposite end it opens into an unfiltrate chamber 72 of the secondary filter 44, which is also delimited by the aforementioned housing parts 58. In this respect, the connecting line 70 connects an unfiltrate chamber 74 of the primary filter 10 with the unfiltrate chamber 72 of the secondary filter 44 in a direct manner, i.e. while maintaining the shortest possible fluid path or route. The free diameter of the connecting line 70 is selected to be significantly smaller than the free diameter of the filter inlet 14 and filter outlet 20, through which the main flow is conducted as unfiltrate stream or filtrate stream.Accordingly, only a portion of the unfiltered material flow awaiting filtration in the primary filter 10 is passed on to the secondary filter 44 for further filtration. If the free end of the connecting line 70 opens into the unfiltered material chamber 74 of the primary filter 10, a secondary or branching point 76 is created, which is located spatially below the filter inlet 14 and branches off the upwardly rising main flow in the primary filter 10 into the connecting line 70 essentially at a right angle. In this way, the primary filter 10, designed as an automatic backwash filter, can filter the main flow during continuous backwashing, whereas the secondary filter 44 in the secondary flow is continuously supplied with a small amount of unfiltered material for a filtration process from the primary filter 10 via the secondary or branching point 76 in the filter container 16, so that continuous fluid cleaning is achieved with both filters 10, 44 during operation.

[0026] As can be further seen from Figures 1 and 2, the connecting line 70 between the two filters 10, 44 can be shut off by means of a shut-off device 78, for example in the form of a changeover valve such as a ball valve. By means of the shut-off device 78, which is shown in its open position according to the illustrations in Figures 1 and 2, the secondary filter 44 can be separated from the primary filter 10, for example for the purpose of performing maintenance work, including replacing a new element with a used or blocked filter element 48 of the secondary filter 44. For such a filter removal process, the multi-part filter housing 46 can be separated from each other, and the interior of the filter housing 46 can also be vented via a conventional venting device 80.Furthermore, a pressure sensor 82 measuring the differential pressure can also be used for the secondary filter 44, which detects the degree of contamination on the filter element 48.

[0027] Both the primary filter 10 and the secondary filter 44 are combined on a platform-like support device 84, which represents a manageable unit and can be transported to the place of use, for example, as a system, by means of a ship's crane. From the illustration in Figure 1, it can be seen that the connecting line 70 and the backwash line 24 are arranged, running at least partially parallel to one another, on the rear side of the filters 10, 44, which is opposite the front side with the filter inlet 14 and the filter outlet 20. In this way, the associated piping is particularly protected, in particular because the support device 84 consists of a solid, welded beam construction.

[0028] The backwash line 24 (not shown in Figure 2) opens with its side adjacent to the clean side 66 into a flange connection point 86, at which the fluid guide 64 with the throttle 68 opens onto the clean side 66 at a T-shaped connection point 88 in the direction of fluid flow. This connection point 88 is in turn delimited by a flange 90, so that together with an annular flange 92 for the fluid inlet 14 and a further annular flange 94 for the filter outlet 20, a total of only three flanges 90, 92, 94 are present, by means of which the system according to Figures 1 and 2 can be integrated into an overall hydraulic supply system, which will be explained in more detail below with reference to Figure 3.

[0029] As can be seen from Figure 3, the system presented in Figures 1 and 2 is preferably integrated into a closed lubrication circuit 96. The circuit 96 has a consumer 98 connected to it, which is to be supplied with lubricant, such as lubricating oil, and which consists, for example, of an internal combustion engine, such as a marine diesel engine. This consumer 98 is supplied with lubricating oil in the main flow, and any excess lubricating oil that is not required or not used, and which is contaminated with particles such as abrasion, is discharged to a tank 100 in a discharge direction as shown by the arrow from the consumer 98 to the tank 100. The tank 100 should be filled with lubricating oil to a predeterminable fill level 102. Ambient pressure should act on the fill level 102.Using a conventional (main lubrication) oil pump 104, lubricating oil can be drawn from the tank 100 in this direction as indicated by the arrow and passed through a pre-filtration stage 106. The oil or feed pump 104 then circulates lubricating oil to the filter inlet 14 of the primary filter 10, and after passing through the primary filter 10, the cleaned fluid main flow reaches an inlet side of the consumer 98 via the filter outlet 20. The consumer 98 in question can have engine components to be lubricated, such as plain bearing shells of a crankshaft (not shown). The backwash line 24 of the primary filter 10 opens via the connection point 88 (Figure 1) onto the clean side 66 of the system and a discharge line 108 is connected to the flange 90 of the connection point 88, which discharge line opens into the storage tank 100, the direction of fluid discharge being again indicated by an arrow.

[0030] In the bypass flow via the bypass or branch point 76, the secondary filter 44 is connected to the main flow filtration bypass and can be separated from the primary filter 10 by means of the shut-off device 78. Furthermore, the aforementioned throttle 68 is located on the outlet side of the secondary filter 44 and thus on the clean side.

[0031] The lubricating oil treatment shown in Figure 3 is preferably carried out via a single-layer filter or candle filter 44 equipped with a very fine cartridge element 48. As shown, the filter 44, which is installed in the bypass flow, receives only a small portion of the lubricating oil provided by the main lubricating oil pump 104. The desired continuous lubricating oil flow is regulated via the throttle 68 installed at the filter outlet, i.e., on the filtrate side of the secondary element 44. For example, if the lubricating oil flow is limited to one cubic meter by means of the throttle 68 and the entire lubricating oil circuit of the consumer 98, including tank 100, amounts to twelve cubic meters, the entire lubricating oil flows through the fine secondary filter element 44 twice in 24 hours, which then leads to very effective lubricating oil treatment.The backwash line 24 of the automatic or primary filter 10 and the outlet in the form of the fluid guide 64 of the secondary filter 44 are brought together in the common flange 90 at the connection point 88, to which a discharge line 108 of the clean side 66 is connected, so that in principle only the three flanges 90, 92 and 94 are required for the installation of the system on board a ship in order to integrate the system into the lubricating oil circuit 96, as shown in Figure 3.

[0032] No external power is required to operate the system with the two filters 10, 44, as the hydraulic motor 26 of the primary or backwash filter 10 is driven by the pressure in the oil lubrication circuit 96. The system and its use in a lubrication circuit 96 for continuous lubricating oil cleaning have proven particularly robust and therefore reliable in operation. Furthermore, all essential system components can be combined in a single source during production, for example, by a filter manufacturer, which in turn helps reduce costs and improves delivery quality.

[0033] A further advantage is that increasing contamination of the secondary filter 44 has no negative effects on the primary filter 10. While in known systems the filter fineness of the secondary filter 44 is usually significantly coarser than the filter fineness of the primary filter 10 in order not to impair filtration by the primary filter 10, according to the solution according to the invention the secondary filter 44 is designed with a significantly higher filter fineness than the filter fineness of the primary filter 10. Furthermore, the available lubricating oil pressure on the unfiltered side is higher than the pressure in the backwash line 24, thus enabling better loading or utilization of the secondary filter 44.

[0034] It is understood that the system claimed and described above need not be limited to applications in lubricating oil treatment, but can be used more or less for all fluids that require a certain degree of cleaning of contaminants and / or gases, with additional fluid treatment in the bypass stream. It is also conceivable that the system could be used for cleaning fuels, such as diesel, for internal combustion engines. This has no equivalent in the prior art.

Claims

Patent claims 1 . System for filtering fluids, comprising at least a primary filter (10) which has at least one filter element (12) through which flow can be carried in one direction for a filtration process and in the opposite direction for a backwash process, and comprising a secondary filter (44) which has at least one further filter element (48), characterized in that a part of an unfiltrate flow awaiting filtration in the primary filter (10) is passed on to the secondary filter (44) for filtration therethrough, and in that the backwash fluid produced during backwashing with the primary filter (10) passes the secondary filter (44) to a clean side (66) to which the secondary filter (44) delivers its amount of filtrate.

2. System according to claim 1, characterized in that the primary filter (10) is an automatic backwash filter which filters in the main flow during continuous backwashing and that the secondary filter (44) in the secondary flow is continuously supplied with unfiltered material from the primary filter (10) for a filtration process, so that continuous fluid cleaning with both filters (10, 44) is achieved.

3. System according to claim 1 or 2, characterized in that the secondary filter (44) has a higher filter fineness than the primary filter (10).

4. System according to one of the preceding claims, characterized in that an unfiltrate chamber (74) of the primary filter (10) is fluid-conductingly connected to an unfiltrate chamber (72) of the secondary filter (44) via a connecting line (70).

5. System according to one of the preceding claims, characterized in that the connecting line (70) between the two filters (10, 44) runs on the bottom side and can be shut off by means of a shut-off device (78).

6. System according to one of the preceding claims, characterized in that the respective filter element (48) of the secondary filter (44) is flowed through from outside to inside during filtration and the primary filter (10) from inside to outside and that for backwashing the respective filter element (12) of the primary filter (10) the latter is flowed through in the opposite direction from outside to inside.

7. System according to one of the preceding claims, characterized in that a throttle (68) is provided on the discharge side (64) of the secondary filter (44) for throttling the associated filtrate flow.

8. System according to one of the preceding claims, characterized in that a backwash device (22) of the primary filter (10) delivers the backwash quantity generated during backwashing at the same time as the filtration to the clean side (66) via an independent backwash line (24).

9. System according to one of the preceding claims, characterized in that the primary filter (10) and the secondary filter (44) together on a carrier device (84) form a manageable structural unit and that the connecting line (70) and the backwash line (24), preferably running at least partially parallel to one another, converge in a common connection point (88) to which a discharge line (108) of the clean side (66) is connected.

10. Use of a system according to one of the preceding claims for a continuous lubricating oil cleaning in a consumer (98), such as an internal combustion engine, in the main flow, a part of which is branched off and led past the consumer (98) and is additionally cleaned in the secondary flow for the realization of lubricating oil maintenance.

Images