Oil purification system

Abstract

An oil purification system and a method for purification of oil. The oil purification system comprises a pump and control unit configured for controlling said oil purification system such that oil can be transferred between a first container and a second container via a filter system. Said filter system comprises at least one filter unit comprising a filter housing configured for housing a replaceable filter insert. Wherein said pump and control unit comprises an oil condition monitoring sensor configured for measuring an oil condition after the oil has passed the filter system, whereby the pump and control unit is configured to reverse the flow between the first and second container and transfer the oil via the filter system once again until a predefined oil condition level has been reached as measured by the oil condition monitoring sensor.

Description

[0001] 202500001

[0002] Oil purification system

[0003] TECHNICAL FIELD OF THE INVENTION

[0004] The present invention relates to an oil purification system and to a method for purification of oil.

[0005] BACKGROUND

[0006] Purification of contaminated oil, such as for example industrial oil, lubrication oil, hydraulic oil or processing oil is important for the possibility to reuse the oils and therefore an important factor for the environmental future and the limited nature resources of oils. Filtering of oil through different types of filters is often used for purification of contaminated oil. However, the efficiency in these filtering techniques is not always enough.

[0007] There is a need to improve the possibility to reuse oils.

[0008] SUMMARY

[0009] It is an object of the present invention to provide an improved oil purification system and method for purification of oil.

[0010] This is achieved by an oil purification system and a method according to the independent claims.

[0011] According to one aspect of the invention an oil purification system is provided, comprising:

[0012] a first fluid connection for connection to a first inlet / outlet of a first container; a second fluid connection for connection to a second inlet / outlet of a second container;

[0013] a pump and control unit comprising at least one pump, said pump and control unit being connectable to said first and second container via said first and second fluid connections; and202500001

[0014] a filter system and filter fluid connections connecting a filter system inlet and a filter system outlet to the first and second fluid connections via the pump and control unit, wherein said filter system comprises at least one filter unit comprising a filter housing configured for housing a replaceable filter insert.

[0015] Said pump and control unit is configured for controlling said oil purification system such that oil can be transferred between the first container and the second container via the filter system, wherein said pump and control unit further comprises an oil condition monitoring sensor configured for measuring an oil condition after the oil has passed the filter system, whereby the pump and control unit is configured to reverse the flow between the first and second container and transfer the oil via the filter system once again until a predefined oil condition level has been reached as measured by the oil condition monitoring sensor.

[0016] According to another aspect of the invention a method for purification of oil in an oil purification system according to the invention is provided. Said method comprises the steps of

[0017] pumping contaminated oil from the one of the first or the second container which comprises contaminated oil to the other one of the first and the second container via the filter system;

[0018] measuring an oil condition by the oil conditioning monitoring sensor after the oil has passed the filter system;

[0019] comparing the measured oil condition with a predefined oil condition level; and reversing the flow between the first and second containers via the filter system if the measured oil condition level has not reached the predefined purified oil condition level.

[0020] Hereby an efficient oil purification system is achieved which is easy to use and which can be used for different types of oil. A first and a second container, for example IBC containers, whereof the first container comprises a contaminated oil to be purified, are connected in the oil purification system according to the invention whereby the contaminated oil is purified in the oil purification system. The contaminated oil is transferred back and forth between the first and the second containers via the filter system until the oil is clean enough as measured by the oil condition monitoring sensor. The replaceable filter inserts of the filter units can be changed both when saturated and between different batches of contaminated oil. Furthermore, different types of filter inserts can be used for different types of contaminated oil. The oil202500001

[0021] purification system according to the invention can be run in semi-automated mode whereby a convenient and efficient oil purification process is achieved. According to the invention the oil condition monitoring sensor will signal when a filter insert needs to be changed. Hereby efficient oil purification is achieved with the oil purification system and method according to the invention.

[0022] In some embodiments of the invention said oil purification system comprises at least a first replaceable filter insert comprising a first filter body which is, at least in a part, impregnated with a separation aid. Thanks to the impregnation of the filter insert with a separation aid the oil filtering efficiency is increased. This way of providing a separation aid to a replaceable filter insert provides a convenient and efficient oil purification because the filter insert can easily be changed and there is no need for another handling of separation aid such as distribution and mixing of separation aid into the contaminated oil.

[0023] In some embodiments of the invention said separation aid has a composition which is substantially insoluble in the contaminated oil to be purified in said oil purification system because of its polar properties and which separation aid will by chemical interactions adsorb / absorb contaminating solids or dissolved impurities in the contaminated oil to be purified.

[0024] In one embodiment of the invention the first filter body comprises a network of cellulose fibers and the separation aid is bonded to the cellulose fibers in at least a part of a volume of the filter body.

[0025] In one embodiment of the invention the oil purification system further comprises at least one second replaceable filter insert, wherein said second replaceable filter insert comprises a second filter body being a depth filter.

[0026] In one embodiment of the invention the oil purification system further comprises a direction change valve system, wherein said first and second fluid connections are connected to the pump and control unit via said direction change valve system, whereby the pump and control unit is configured to control the direction change valve system to reverse the flow between the first and second container and transfer the oil via the filter system once again until a predefined oil condition level has been reached as measured by the oil condition monitoring sensor.202500001

[0027] In one embodiment of the invention the filter system comprises two or more filter units connected in parallel. In one embodiment of the invention the filter system comprises four or more or six or more filter units connected in parallel. The use of more than one filter unit provides a flexible oil purification system in which the number of connected filter units can be chosen by the user. Furthermore the user can choose which types of filter inserts to use in the filter units hereby providing a flexible system useful for purification of different types of contaminated oils.

[0028] In one embodiment of the invention the oil condition monitoring sensor is an optical sensor.

[0029] In one embodiment of the invention the oil purification system further comprises at least one air sensor which is provided in connection with the first and / or second fluid connections whereby an output from said air sensor can be used by the pump and control unit for detecting when oil is no longer transferred from the first or second container. Hereby it can be detected when one of the containers is empty and the whole amount of oil has been transferred from one container to the other.

[0030] In one embodiment of the invention the oil purification system further comprises at least one spill tray onto which said first and second containers can be provided and onto which said pump and control unit and said filter system are provided. Said at least one spill tray may comprise a leakage sensor for detection of oil leakage.

[0031] In one embodiment of the invention the oil purification system further comprises a heating means configured for heating the contaminated oil before it is forwarded to the filter system. Hereby the flow of oil through the oil purification system can be increased and the capacity of the system can also be increased.

[0032] In one embodiment of the invention said at least one filter housing is arranged in the oil purification system such that it can be swiveled from a vertically aligned position into an inclined position for facilitating emptying of the filter housing via an draining opening provided off center in a bottom part of the filter housing. Hereby cleaning of the system is facilitated and contamination between different batches of oil to be purified in the system can be avoided.

[0033] In one embodiment of the invention the oil purification system further comprises a first and a second container top connector configured for being connected to a top opening of the first and the second container respectively, wherein said first and second container top connectors202500001

[0034] comprises an oil level sensor configured for measuring an oil level in the connected first or second container.

[0035] In one embodiment of the invention said pump and control unit comprises a communication means for communication with an external device for remote monitoring and / or control of the oil purification system.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 shows schematically an oil purification system according to one example of the invention.

[0038] Figure 2 is a schematic illustration of fluid connections in an oil purification system according to one example of the invention.

[0039] Figure 3 is a schematic illustration of a filter system according to one example of the invention.

[0040] Figure 4 is a schematic perspective view of an oil purification system according to one example of the invention.

[0041] Figure 5a is a schematic perspective view partly in cross section of a filter unit according to one example of the invention.

[0042] Figure 5b is a schematic perspective view of a filter insert according to one example of the invention.

[0043] Figure 5c is a schematic view from above of a filter housing according to one example of the invention.

[0044] Figure 6 is a flow chart of a method according to one embodiment of the invention.

[0045] DETAILED DESCRIPTION OF EMBODIMENTS

[0046] According to the invention an oil purification system and a method for purification of oil in such an oil purification system are provided. In Figures 1, 2 and 4 an oil purification system 1 according to one example of the invention is illustrated in different ways and with different202500001

[0047] levels of details. The oil purification system 1 as shown in Figure 4 includes more specific details but is only given as an example and should not be regarded as limiting. For example, as also illustrated in Figure 3, the number of filter units 11 and how they are connected and arranged can of course be varied within the scope of the invention.

[0048] An oil purification system 1 according to the invention will first be described more generally with reference to all the drawings. The oil purification system 1 comprises a first fluid connection 3a for connection to a first inlet / outlet 4a of a first container 5a and a second fluid connection 3b for connection to a second inlet / outlet 4b of a second container 5b. The first and second containers 5a, 5b may be movable IBCs (Intermediate Bulk Containers) which can be easily connected to the oil purification system 1 via the first and second fluid connections 3a, 3b. The oil purification system 1 comprises further a pump and control unit 21. The pump and control unit 21 comprises at least one pump 23 and fluid connections for connecting the at least one pump 23 with the first and second fluid connections 3a, 3b and with a filter system 10 which will be further described below. The pump and control unit 21 further comprises one or more sensors 31a, 31a’, 3 lb, a heating means 45 and possibly a communication means 22a which will be further described below. The oil purification system 1 comprises furthermore suitably a direction change valve system 25 provided in connection with the first and second fluid connections 3a, 3b and with the pump and control unit 21 such that the pump 23 can pump fluid either from the first container 5a or from the second container 5b in dependence on how the direction change valve system 25 is controlled. The direction change valve system 25 may be positioned differently in the oil purification system, for example between the pump and control unit 21 and the filter system 10 instead. Another configuration of valves may also be possible to use. The function of such a direction change valve system is however to reverse the flow between the first and second containers while keeping the same direction of flow through the filter system 10.

[0049] The oil purification system 1 comprises furthermore a filter system 10 and filter fluid connections 13 connecting a filter system inlet 10a and a filter system outlet 10b to the first and second fluid connections 3a, 3b via the pump and control unit 21. The filter system 10 comprises at least one filter unit 11. In some embodiments of the invention at least two or at least three or at least four or six filter units 11 are provided. The filter units 11 may be connected in parallel. In Figure 3 one example of a filter system 10 which can be used in the oil purification system 1 as shown in Figures 1, 2 and 4 is schematically illustrated. Here ten filter units 11 are connected in parallel. The number of filter units 11 can of course be varied.202500001

[0050] Each filter unit 11 is here provided with a filter valve 26 such that the filter units 11 to be used can be chosen by controlling the filter valves 26 from the pump and control unit 21. It may for example be useful to connect more filter units 11 for the oil purification if the oil purification needs to be done very fast. If on the other hand there is no time restriction it may be more economically efficient to use fewer filter units 11 for the oil purification.

[0051] Figure 5a is a schematic perspective view partly in cross-section of a filter unit 11 according to one example of the invention. The filter unit 11 comprises a filter housing 15a inside which a replaceable filter insert 15b, 115b can be provided. Figure 5b is a schematic perspective view of a replaceable filter insert 15b, 115b according to one example of the invention and Figure 5c is a schematic view from above of a filter housing 15a according to one example of the invention. The replaceable filter insert can be a first replaceable filter insert 15b and in some embodiments also a second replaceable filter insert 115b. The first replaceable filter insert 15b comprises a first filter body 15c which is, at least in a part, impregnated with a separation aid. The first filter body 15c may for example comprise a network of cellulose fibers whereby the separation aid is bonded to the cellulose fibers in at least a part of a volume of the filter body 15c. The separation aid has a composition which is substantially insoluble in the contaminated oil to be purified in said oil purification system because of its polar properties and which separation aid will by chemical interactions adsorb / absorb contaminating solids or dissolved impurities in the contaminated oil to be purified. Hereby oil purification is improved. The separation aid is described in further details below. The second replaceable filter insert 115b comprises a second filter body 115c being a depth filter, for example comprising a network of cellulose or another type of depth filter, however not impregnated by a separation aid. For the purification of some types of contaminated oil it would be preferred to not use a separation aid, for example for avoiding removal of some specific oil components and hereby it may be suitable to have the possibility to use filter inserts 115b without separation aid.

[0052] In Figure 5a a filter unit inlet Ila and a filter unit outlet 1 lb are shown in a bottom part 12a of the filter housing 15a. Contaminated oil to be purified in the filter unit 11 is entered via the filter unit inlet Ila and forwarded between the replaceable filter insert 15b, 115b and inner walls 12b of the filter housing 15a from the bottom part 12a of the filter housing 15a towards an upper cap 12c of the filter housing 15a. The contaminated oil enters into the filter body 15c, 115c of the replaceable filter insert 15b, 115b from atop surface 15b’, 115b’ of the filter insert 15b, 115b. The contaminated oil is then transferred through the filter body 15c, 115c of202500001

[0053] the replaceable filter insert 15b, 115b and exits the replaceable filter insert 15b, 115b via the filter unit outlet 1 lb which is provided in a centre of the filter housing 15a and a centre of the replaceable filter insert 15b, 115b.

[0054] The pump and control unit 21 is configured for controlling said oil purification system 1, for example controlling the pump 23 and said direction change valve system 25, such that oil can be transferred between the first container 5a and the second container 5b via the filter system 10. The pump and control unit 21 comprises further at least one oil condition monitoring sensor 31a, 31a’ configured for measuring an oil condition after and possibility also before the oil has passed the filter system 10. The pump and control unit 21 is configured to control the oil purification system 1 to reverse the flow between the first and second container 5a, 5b, by controlling the direction change valve system 25, and transfer the oil via the filter system 10 once again until a predefined oil condition level has been reached as measured by the oil condition monitoring sensor 31a. Suitably the whole volume of contaminated oil provided in the first container 5a is transferred via the filter system 10 to the second container 5b and then, if further purification is needed, the direction change valve 25 is controlled such that the oil can be pumped from the second container 5b, via the filter system 10 in the same direction through the filter system 10 as the first time and then back to the first container 5a. And this can be repeated until the oil has been purified enough according to predefined oil condition levels, for example based on particle counting. This process can be at least partially automated. Said pump and control unit 21 is suitably configured for controlling the oil purification in the oil purification system in a semi-automated manner, i.e. the pump 23 and the direction change valve system 25 may be controlled automatically based on output from the oil condition monitoring sensor 31a. Two oil condition monitoring sensors 31a, 31a’ may be provided where one measures the oil condition of the oil before the oil enters the filter system 10 and one measures the oil condition of the oil after the oil has passed the filter system 10. This is for example suitable for assessing filter saturation or malfunctioning. If the two oil condition monitoring sensors show the same or almost the same result the replaceable filter insert 15b, 115b may be saturated or malfunctioning.

[0055] The one or more oil condition monitoring sensors 31a, 31a’ can suitably be optical sensors. Hereby particles in the oil can be counted, enabling the use of a suitable standard, such as an ISO standard, such as ISO 4406 particle count.202500001

[0056] The oil purification system 1 may further comprise at least one air sensor 3 lb which is provided in connection with the first and / or the second fluid connections 3a, 3b whereby an output from said air sensor 3 lb can be used by the pump and control unit 21 for detecting when oil is no longer transferred from the first or second container 5a, 5b, i.e. when the first or second container 5a, 5b is empty and the whole amount of oil has been transferred to the other one of the first or second container 5a, 5b. Hereby the oil purification method performed in the oil purification system 1 can be automated, at least to some degree. In Figure 1 one air sensor 3 lb is shown. However, in another embodiment two air sensors can be provided, one in connection with the first fluid connection 3a and one in connection with the second fluid connection 3b (and possibly positioned on the other side of the direction change valve 25 compared to where the air sensor 3 lb in Figure 1 is positioned).

[0057] As illustrated in Figures 1 and 4, the oil purification system 1 may also comprise at least one spill tray 41a, 41b onto which said first and second containers 5a, 5b can be provided and onto which said pump and control unit 21 and said filter system 10 are provided. The at least one spill tray 41a, 41b comprises a leakage sensor 31c for detection of oil leakage. In the oil purification systems 1 as illustrated in Figures 1 and 4 a first spill tray 41a and a second spill tray 41b are provided, where the first and second containers 5a, 5b are to be provided onto the first spill tray 41a and the pump and control unit 21 and the filter system 10 are provided on the second spill tray 41b. In this example there is a leakage sensor 31c provided on each of the two spill trays 41a, 41b. However, in another embodiment only one spill tray is provided onto which all components of the oil purification system 1 can be provided, including the first and second containers 5a, 5b.

[0058] The oil purification system 1 may also comprise a heating means 45 as schematically illustrated in Figures 1 and 2. The heating means 45 is configured for heating the contaminated oil before it is forwarded to the filter system 10. The oil purification system 1 may also comprise a temperature sensor 3 le. The heating means 45 can also be controlled to change heating temperature in dependence on measured oil temperature as measured by the temperature sensor. The heating means 45 may also be controlled in dependence on a flow level of the oil as measured by a flow meter 3 If provided in the oil purification system 1. If the oil flow is low, heating of the oil can increase the flow and hereby increase capacity of the oil purification system.202500001

[0059] In some embodiments said at least one filter housing 15a is arranged in the oil purification system 1 such that it can be swiveled from a vertically aligned position into an inclined position for facilitating emptying of the filter housing 15a via a draining opening 112 provided off center in the bottom part 12a of the filter housing 15a. The draining opening 112 in the bottom part 12a of the filter housing 15a is suitably designed without any surrounding bulge hereby enabling complete emptying of the filter housing 15a. This is important because the oil purification system 1 according to the invention can be used to purify different types of contaminated oils provided in different batches in containers which are used as the first container 5a which is provided to the oil purification system 1 according to the invention. Hereby complete emptying of the filter housings 15a is important between purification of different batches in order to avoid cross-contamination between different oils to be purified in the oil purification system 1.

[0060] The oil purification system 1 may further comprise a first and a second container top connector 51a, 51b configured for being connected to a top opening 105a, 105b of the first and the second container 5a, 5b respectively, wherein said first and second container top connectors 51a, 51b comprises an oil level sensor 3 Id configured for measuring an oil level in the connected first or second container 5 a, 5b. The first and second container top connector 51a, 51b may further comprise air inlet / outlet for dried and clean air and possibly an overflow sensor. The first and second container top connectors 51a, 51b may both have a weight such that they seal the top openings 105a, 105b of the containers 5a, 5b. The first and second container top connectors 51a, 51b may have a wired or wireless communication contact with the pump and control system 21. In Figure 1 first and second container top connectors 51a, 51b are schematically shown connected to top openings 105a, 105b of the first and second container 5a, 5b. In Figure 4, however there are no container top connectors provided to the top openings 105a, 105b of the first and second container 5a, 5b. Optionally top connectors 51a, 51b can be provided also in the system as shown in Figure 4.

[0061] The pump and control unit 21 may also comprise a communication means 22a for communication with an external device 22b for remote monitoring and / or control of the oil purification system 1. The communication means 22a is for example configured for forwarding alarms from the oil purification system 1, such as alarm of a leakage detected by the leakage sensor 31c in the one or more spill trays 41a, 41b. Other information which may202500001

[0062] be forwarded from the communication means 22a to an external device 22b can be information about the replaceable filter inserts 15b, 115b, such as filter saturation which can be concluded by the oil condition monitoring sensor 3 la if particles are not removed from the oil by the filtration and filter clogging which can be detected by a flow detector if a flow through the filter system is too low. Even further, information about finished cleaning can be transferred to the external device 22b and alarm about the first or second container 5a, 5b being empty or overfilled as measured by the oil level sensor 3 Id or the air sensor 3 lb.

[0063] Figure 6 is a flow chart showing method steps of a method for purification of oil in an oil purification system 1 according to the invention and as described above with reference to Figures 1-5. The method steps are described below:

[0064] SI : Pumping contaminated oil from the one of the first or the second container 5a, 5b which comprises contaminated oil to the other one of the first and the second container 5a, 5b via the filter system 10.

[0065] S2: Measuring an oil condition level by the oil conditioning monitoring sensor 31a after the oil has passed the filter system 10.

[0066] S3: Comparing the measured oil condition level with a predefined purified oil condition level.

[0067] S4: Reversing the flow between the first and the second containers 5a, 5b via the filter system 10, by controlling the direction change valve system 25, if the measured oil condition level has not reached the predefined purified oil condition level.

[0068] Steps S1-S4 are repeated until the predefined oil condition level has been reached as measured by the oil condition monitoring sensor 31a.

[0069] As discussed above the oil condition monitoring sensor 31a can for example be an optical sensor whereby particles in the oil can be counted. Hereby the predefined purified oil condition level can be a set amount of particles according to a standard, such as an ISO standard, for example ISO 4406 standard.

[0070] The first replaceable filter insert 15b comprises a filter body 15c which is impregnated at least in a part with a separation aid as described above. The separation aid composition is substantially insoluble in a contaminated oil to be purified by said oil purification filter because of its polar properties and the separation aid will by chemical interactions adsorb / absorb contaminating solids or dissolved impurities in the oil to be purified.202500001

[0071] A separation aid which is used in this invention has in some embodiments a density being different from that of the oil to be purified. The separation aid attracts impurities in the oil when oil and separation aid come in contact.

[0072] The use of a separation aid, also called a chemical booster or separation booster, for capturing impurities in contaminated oil has been described before, see for example WO 2018 / 199839. Here a liquid separation booster / aid is added to the oil and mixed therewith and impurities in the oil will be captured by the separation aid and will accumulate in a phase which can be separated, for example a bottom phase.

[0073] The separation aid will by chemical interactions adsorb / absorb contaminating solids, or dissolved impurities in the contaminated target oil. The separation aid can be liquid at the temperature at which the step of impregnation is carried out. The separation aid composition should be substantially insoluble in the contaminated target oil, forming a two-phase liquid mixture if mixed with the contaminated oil. The liquid separation aid can also have a density different from that of the contaminated oil to be purified.

[0074] The separation aid is not soluble in the contaminated target oil because of its polar properties and will through chemical interactions (hydrophilic, hydrophobic, and / or charge interactions) adsorb / absorb unwanted solid or dissolved impurities in the contaminated target oil.

[0075] The liquid separation aid / booster for use in the invention can generally be made up based on the following components: a) a polar polymer; b) a hydrotrope / solubilizer; and, c) a co-tenside.

[0076] Suitable separation aids with the properties described above, that can be used in the inventive process, may e.g. constitute a composition comprising a mixture of polar polymers such as polyethylene glycols, polypropylene glycols or similar polyalkylene glycols, organic surface active components with nonionic, anionic, cationic and amphoteric properties with the ability to enhance the solubility of solid or dissolved impurities in to the separation aid.

[0077] One example of a separation aid which can be used in this invention comprise: a) at least one polar polymer not soluble in oil and with a higher density than the oil, such as polyethylene glycol with an average molecular weight of 190-210 g / mole, e.g. Carbowax PEG 200 (Dow Chemical Company); b) at least one surface active hydrotrope / solubilizer, such as anionic sulfonic acids, phosphate ester-based substances or non-ionic surfactants from the poly-202500001

[0078] glycoside family, such as Simulsol SL 4, Simulsol SL 7 G and Simulsol AS 48 (Seppic, Air Liquide group); c) at least one amphoteric Co-surfactant, such as an propionate type e.g. Ampholak YJH-40 (Akzo Nobel) which is a sodium caprylimino dipropionate.

[0079] The separation aid may further have a sufficiently big difference in polarity compared to a polarity of at least one specific additive in the contaminated oil to be purified such that the at least one specific additive is not soluble in the separation aid.

[0080] The filter body 15c, 115c of the first and second replaceable filter inserts 15b, 115b can be a depth filter and may comprise cellulose fibers. In some embodiments of the invention a network of cellulose fibers is provided in the filter body. For the first replaceable filter insert 15b the separation aid can be bonded to the cellulose fibers in at least a part of a volume of the filter body. The impregnation of separation aid to the filter material can be done in different ways. For example a part of the filter material can be soaked into the separation aid (possibly into a solution of separation aid and water), or be sprayed with separation aid (possibly separation aid and water) or the separation aid mixed with oil can be flowed over the filter material for providing the impregnation. In order to achieve a stronger bond between the cellulose fibers and the separation aid the cellulose fibers can be wetted before or during impregnation. Optionally a bonding agent could also be added for providing an even stronger and possibly tailor-made bond between the cellulose fibers and the separation aid. In one embodiment the separation aid is applied to the filter material during a sheet forming process where a cellulose fiber suspension is processed into sheets. By applying the separation aid during this process, i.e. during a stage in the process where the cellulose fibers are still wet and before a final filter product is achieved the bond between the separation aid and the cellulose fibers will be stronger. Wet cellulose fibers are swollen and separation aid can be caught within the fibers when the cellulose fibers are dried and their swollen state collapses. The separation aid may also be bonded to the cellulose fibers by hydrogen bonds. Hereby, in some embodiments of the invention said bonding between the separation aid and the cellulose fibers has been provided by applying the separation aid to the cellulose fibers during a process for forming the cellulose fibers to a filter body at a stage in the process where a dryness is 20-60 % dry mass of cellulose fiber to total mass of the cellulose fiber network.

[0081] In some embodiments of the invention the filter body comprises a number of layers of sheets of filter material which are provided onto each other as a stack of separate sheets and / or as a cylinder with one or more sheets wound in layers around an inner cylinder. Each of said202500001

[0082] layers of sheets of filter material comprise a network of cellulose fibers and at least some of the sheets or at least one sheet or at least a part of a sheet of filter material further comprise separation aid which is bonded to the cellulose fibers. The interfaces between individual sheets will aid in retaining the separation aid within individual sheets.

[0083] The filter body can for example comprise a cellulose fiber material having a density without bonded separation aid within the interval of 100-600 kg cellulose / m3. With separation aid bonded to 50% in this filter material the density of the filter body would be within the interval of 150-900 kg / m3. If instead talking about basis weight of a suitable cellulose filter it can for example be within the interval of 50-1500 kg cellulose / m2for filter material without bonded separation aid and with 50% bonded separation aid this would be within the interval of 75-2250 kg / m2.

Claims

202500001CLAIMS1. An oil purification system (1) comprising:a first fluid connection (3a) for connection to a first inlet / outlet (4a) of a first container (5a);a second fluid connection (3b) for connection to a second inlet / outlet (4b) of a second container (5b);a pump and control unit (21) comprising at least one pump (23), said pump and control unit (21) being connectable to said first and second container (5a, 5b) via said first and second fluid connections (3a, 3b); anda filter system (10) and filter fluid connections (13) connecting a filter system inlet (10a) and a filter system outlet (10b) to the first and second fluid connections (3a, 3b) via the pump and control unit (21), wherein said filter system (10) comprises at least one filter unit (11) comprising a filter housing (15a) configured for housing a replaceable filter insert (15b, 115b),wherein said pump and control unit (21) is configured for controlling said oil purification system (1) such that oil can be transferred between the first container (5a) and the second container (5b) via the filter system (10), wherein said pump and control unit (21) further comprises an oil condition monitoring sensor (31a) configured for measuring an oil condition after the oil has passed the filter system, whereby the pump and control unit (21) is configured to reverse the flow between the first and second container (5a, 5b) and transfer the oil via the filter system (10) once again until a predefined oil condition level has been reached as measured by the oil condition monitoring sensor (31a).

2. Oil purification system according to claim 1, wherein said oil purification system (1) comprises at least a first replaceable filter insert (15b) comprising a first filter body (15c) which is, at least in a part, impregnated with a separation aid.

3. Oil purification system according to claim 2, wherein said separation aid has a composition which is substantially insoluble in the contaminated oil to be purified in said oil purification system because of its polar properties and which separation aid202500001will by chemical interactions adsorb / absorb contaminating solids or dissolved impurities in the contaminated oil to be purified.

4. Oil purification system according to claim 2 or 3, wherein the first filter body (15c) comprises a network of cellulose fibers and wherein the separation aid is bonded to the cellulose fibers in at least a part of a volume of the filter body (15c).

5. Oil purification system according to any one of the preceding claims, wherein the oil purification system (1) further comprises at least one second replaceable filter insert (115b), wherein said second replaceable filter insert (115b) comprises a second filter body (H5c) being a depth filter.

6. Oil purification system according to any one of the preceding claims, further comprising a direction change valve system (25), wherein said first and second fluid connections (3a, 3b) are connected to the pump and control unit (21) via said direction change valve system (25), whereby the pump and control unit (21) is configured to control the direction change valve system (25) to reverse the flow between the first and second container (5a, 5b) and transfer the oil via the filter system (10) once again until a predefined oil condition level has been reached as measured by the oil condition monitoring sensor (31a).

7. Oil purification system according to any one of the preceding claims, wherein the filter system (10) comprises two or more filter units (11) connected in parallel.

8. Oil purification system according to any one of the preceding claims, wherein the oil condition monitoring sensor (31a) is an optical sensor.

9. Oil purification system according to any one of the preceding claims, further comprising at least one air sensor (3 lb) which is provided in connection with the first and / or second fluid connections (3a, 3b) whereby an output from said air sensor (31b) can be used by the pump and control unit (21) for detecting when oil is no longer transferred from the first or second container (5a, 5b).20250000110. Oil purification system according to any one of the preceding claims, further comprising at least one spill tray (41a, 41b) onto which said first and second containers (5a, 5b) can be provided and onto which said pump and control unit (21) and said filter system (10) are provided, said at least one spill tray (41a, 41b) comprises a leakage sensor (31c) for detection of oil leakage.

11. Oil purification system according to any one of the preceding claims, further comprising a heating means (45) configured for heating the contaminated oil before it is forwarded to the filter system (10).

12. Oil purification system according to any one of the preceding claims, wherein said at least one filter housing (15a) is arranged in the oil purification system (1) such that it can be swiveled from a vertically aligned position into an inclined position for facilitating emptying of the filter housing (15a) via an draining opening (112) provided off center in a bottom part (12a) of the filter housing (15a).

13. Oil purification system according to any one of the preceding claims, further comprising a first and a second container top connector (51a, 51b) configured for being connected to a top opening (105a, 105b) of the first and the second container (5 a, 5b) respectively, wherein said first and second container top connectors (51a, 51b) comprises an oil level sensor (3 Id) configured for measuring an oil level in the connected first or second container (5a, 5b).

14. Oil purification system according to any one of the preceding claims, wherein said pump and control unit (21) comprises a communication means (22a) for communication with an external device (22b) for remote monitoring and / or control of the oil purification system (1).

15. A method for purification of oil in an oil purification system (1) according to any one of the preceding claims, said method comprising the steps of202500001pumping (SI) contaminated oil from the one of the first or the second container (5a, 5b) which comprises contaminated oil to the other one of the first and the second container (5a, 5b) via the filter system (10);measuring (S2) an oil condition level by the oil conditioning monitoring sensor (31a) after the oil has passed the filter system (10);comparing (S3) the measured oil condition level with a predefined oil condition level; andreversing (S4) the flow between the first and second containers (5a, 5b) via the filter system (10) if the measured oil condition level has not reached the predefined purified oil condition level.

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