US-12616925-B2 - Oil purification filter

Abstract

An oil purification filter for purifying a contaminated oil includes a filter body having a first portion and a second portion, where at least the first portion is impregnated with a separation aid. The separation aid is substantially insoluble in the contaminated oil because of its polar properties, and the separation aid is configured to adsorb/absorb contaminating solids or dissolved impurities in the contaminated oil by chemical interactions. The filter body may comprise one or more sheets of cellulose fibers.

Inventors

• Tomas OESTBERG
• Karl Enquist
• Thomas Persson

Assignees

• SKF RECONDOIL AB

Dates

Publication Date

20260505

Application Date

20210602

Priority Date

20200605

Claims (20)

1. 1 . An oil purification filter for purifying a contaminated oil, the filter comprising: a filter body composed of a network of cellulose fibers, wherein: the filter body has a first portion and a second portion, at least the first portion is impregnated with a separation aid, the separation aid is substantially insoluble in the contaminated oil because of polar properties of the separation aid, the separation aid is formulated to adsorb/absorb contaminating solids and/or dissolved impurities in the contaminated oil by hydrophilic, hydrophobic, and/or charge interactions, and the oil purification filter is configured as a filter insert mountable in a filter housing.
2. 2 . The oil purification filter according to claim 1 , wherein the oil purification filter is formulated to allow at least one specific additive in the contaminated oil to pass through the filter.
3. 3 . An oil purification filter for purifying a contaminated oil, the filter comprising a filter body having a first portion and a second portion, at least the first portion being impregnated with a separation aid, the separation aid being substantially insoluble in the contaminated oil because of polar properties of the separation aid and the separation aid being configured to adsorb/absorb contaminating solids or dissolved impurities in the contaminated oil by chemical interactions; wherein the filter body comprises a network of cellulose fibers and wherein the separation aid is bonded to the cellulose fibers in at least the first portion of the filter body; wherein the first portion is provided between an inlet of the filter and the second portion and the second portion is provided between an outlet of the filter and the first portion and wherein the second portion is not impregnated with the separation aid.
4. 4 . The oil purification filter according to claim 1 , wherein the filter body comprises a plurality of sheets of filter material arranged in layers to form a stack and/or at least one sheet of the filter material wound in layers around an inner cylinder.
5. 5 . The purification filter according to claim 3 , wherein the oil purification filter is configured as a filter insert mountable in a filter housing.
6. 6 . A method for producing an oil purification filter for purifying a contaminated oil, the method comprising: providing a filter body that comprises a filter material composed of a network of cellulose fibers, the filter material having a first portion and a second portion; impregnating only the first portion of the filter material with a separation aid, the separation aid being (i) a liquid at the temperature at which the impregnation is carried out, (ii) substantially insoluble in the contaminated oil because of polar properties of the separation aid and (iii) formulated to adsorb/absorb contaminating solids and/or dissolved impurities in the contaminated oil by hydrophilic, hydrophobic, and/or charge interactions; and disposing the filter body in a filter housing in an orientation such that the first portion of the filter material is disposed between an inlet of the filter housing and the second portion of the filter material, and the second portion of the filter material is disposed between an outlet of the filter housing and the first portion of the filter material, wherein the second portion of the filter material is not impregnated with the separation aid.
7. 7 . The method according to claim 6 , wherein prior to impregnating only the first portion of said filter material with the separation aid, the cellulose fiber network is brought into a swollen state by applying water to a dry mass of the network of cellulose fibers, and the dryness of the wetted network of cellulose fibers is then adjusted to a ratio of the dry mass of the network of cellulose fibers to the total mass of the wetted network of cellulose fibers that is 20-60%.
8. 8 . The method according to claim 7 , wherein: providing the filter body comprises stacking a plurality of sheets of the filter material to form layers and/or winding at least one sheet of the filter material in layers around an inner cylinder.
9. 9 . The method according to claim 6 , wherein: the step of impregnating only the first portion of said filter material at least partly occurs during the step of providing the filter body, the step of providing the filter body further comprises: forming one or more sheets of the filter material; and stacking two or more of the sheets onto each other and/or winding the at least one of the one or more sheets around an inner cylinder to form the filter body, the step of forming the one or more sheets comprises: suspending cellulose fiber material having a dry first mass in water to form a cellulose fiber suspension comprising cellulose fibers in a singularized, swollen state, and de-watering the cellulose fiber suspension, using gravity or gravity and vacuum, until the one or more sheets has (have) a wetted second mass, and the ratio of the dry first mass to the wetted second mass of the cellulose fiber network is 20-60%, and the impregnating step is performed when the ratio of the dry first mass to the wetted second mass is 20-60%.
10. 10 . The method according to claim 6 , wherein the impregnating comprises soaking only the first portion of the filter material in the separation aid or in a solution of the separation aid and water and/or spraying only the first portion of the filter material with the separation aid or with a solution of the separation aid and water and/or flowing the separation aid mixed with an oil over only the first portion of the filter material.
11. 11 . The method according to claim 6 , further comprising drying the impregnated filter material to 90-100% of the dry mass of the network of cellulose fibers to the total mass of the network of cellulose fiber after the impregnating and prior to disposing the fiber body in the filter housing.
12. 12 . An oil purification filter produced according to the method of claim 6 .
13. 13 . The oil purification filter according to claim 12 , wherein the separation aid is bonded to the network of cellulose fibers in only the first portion of the filter body.
14. 14 . The oil purification filter according to claim 13 , wherein the filter body comprises a plurality of sheets of the network of filter material arranged in layers to form a stack and/or at least one sheet of the network of filter material wound in layers around an inner cylinder.
15. 15 . An oil purification system comprising the oil purification filter according to claim 1 , wherein said oil purification system is configured to be fluidly connected to a technical equipment which is using oil such that the oil is circulated through the oil purification filter for purification of the oil.
16. 16 . The oil purification system according to claim 15 , comprising a filter housing in which said oil purification filter is removably provided, wherein: an inlet of the filter is fluidly connected to an inlet of the filter housing, an outlet of the filter is fluidly connected to an outlet of the filter housing, and said oil purification system further comprises an inlet fluid connection fluidly connected to the inlet of the filter housing, and an outlet fluid connection fluidly connected to the outlet of the filter housing such that the contaminated oil is flowable into the inlet of the filter housing via the inlet fluid connection, through the filter housing and through the oil purification filter and further out from the filter housing through the outlet of the filter housing and further through the outlet fluid connection.
17. 17 . The oil purification system according to claim 16 , further comprising at least one oil condition monitoring sensor for measuring a value indicative of a condition of an oil purified in said oil purification system.
18. 18 . The oil purification system according to claim 16 , wherein: the first portion of the filter material is disposed closer to the inlet than the second portion of the filter material, and the second portion of the filter material is disposed closer to the outlet than the first portion of the filter material.
19. 19 . The oil purification system according to claim 18 , wherein the layers of the filter body are arranged in the filter housing such that the contaminated oil will flow predominantly along and parallel to the layers.
20. 20 . The oil purification filter according to claim 1 , further comprising: the filter housing having an inlet and an outlet, wherein: only the first portion is impregnated with the separation aid, and the second portion is not impregnated with any separation aid, and the filter body is mounted in the filter housing such that the first portion of the filter body is closest to the inlet and the second portion of the filter body is closest to the outlet.

Description

CROSS-REFERENCE This application is the U.S. National Stage of International Application No. PCT/EP2021/064755 filed on Jun. 2, 2021, which claims priority to German patent application no. 10 2020 207 112.8 filed on Jun. 5, 2020. TECHNICAL FIELD OF THE INVENTION The present invention relates to an oil purification filter and to an oil purification system comprising such an oil purification filter and to a method for producing an oil purification filter. BACKGROUND 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 the purification of contaminated oil. However, the efficiency of these filtering techniques is not always adequate. Furthermore, there may be a risk that valuable components in the oil such as additives will also be removed by the filtering. There is a need to improve the possibility to reuse oils. SUMMARY It is therefore one non-limiting object of the present teachings to disclose techniques for improving an oil purification filter. It is another non-limiting object of the present teachings to disclose techniques for improving an oil purification system which can be used for cleaning oil used in a technical equipment, such as for example gear boxes and hydraulic systems. According to one aspect of the present teachings, an oil purification filter may comprise a filter body which is, at least in a first part (portion) of a volume of the filter body, impregnated with a separation aid, which separation aid composition is substantially insoluble in a contaminated oil to be purified by said oil purification filter because of its polar properties and which separation aid will, by chemical interactions, adsorb/absorb contaminating solids and/or dissolved impurities in the oil to be purified. According to another aspect of the present teachings, a method for producing an oil purification filter may comprise: providing a filter material;impregnating at least a part (portion) of the filter material with a separation aid, which separation aid is substantially insoluble in a contaminated oil to be purified by said oil purification filter because of its polar properties and which separation aid will, by chemical interactions, adsorb/absorb contaminating solids and/or dissolved impurities in the oil to be purified; andproducing a filter body from said filter material. According to another aspect of the present teachings, an oil purification filter may comprise a filter body which is, at least in a first part (portion) of a volume of the filter body, impregnated with a separation aid, which separation aid is substantially insoluble in a contaminated oil to be purified by said oil purification filter because of its polar properties and which separation aid will, by chemical interactions, adsorb/absorb contaminating solids and/or dissolved impurities in the oil to be purified, wherein said oil purification filter is produced by the above-described method. According to another aspect of the present teachings, an oil purification system comprising an oil purification filter as defined above is provided, wherein the oil purification system is configured to be connected to a technical equipment which utilizes oil such that the oil is circulated through the oil purification filter for the purification of the oil. According to the present teachings, a very effective oil purification filter is provided. Even very small contamination particles, as small as micro and nano particles, are caught in the filter thanks to the separation aid which is impregnated in at least a part (portion) of the filter volume. The separation aid is designed to, by chemical interactions, adsorb/absorb contaminating solids. The actual filter pore dimensions can in this filter be provided large enough to allow certain additives to pass therethrough. Consequently, additives that are valuable to keep in the oil can be kept in the oil during filtration; i.e. such additives will not be caught in the filter. This is a great advantage compared to other types of fine filters in which valuable additives also might be filtered out from the oil. In some embodiments of the present teachings, the oil purification filter is configured to clean a contaminated oil that comprises at least one specific additive and the separation aid is designed (formulated) to be passive, i.e. not attracting, with respect to said at least one specific additive in the contaminated oil to be purified. As a result, valuable additives can be kept in the oil; i.e. they will not be caught in the oil purification filter during purification of the oil. In some embodiments of the present teachings, the filter body comprises a network of cellulose fibers and the separation aid is bonded to the cell