Purification of oil
阅读说明:本技术 油的净化 (Purification of oil ) 是由 F.桑德斯特伦 T.佩尔森 于 2018-04-24 设计创作,主要内容包括:用于油的净化的方法和系统,所述方法包括以下步骤:-向至少一个沉降箱提供分离助剂和待净化的油;-等待以允许淤渣相沉降到沉降箱的底部部分,所述淤渣相包括与来自油的杂质一起的分离助剂;-从至少一个沉降箱去除不包括所述淤渣相的油相;以及-通过深度过滤器过滤所述油相以用于去除任何可能的剩余分离助剂和杂质。(A method and system for the purification of oil, the method comprising the steps of: -providing a separation aid and the oil to be purified to at least one settling tank; -waiting to allow a sludge phase to settle to the bottom part of the settling tank, said sludge phase comprising separation aids together with impurities from the oil; -removing an oil phase excluding the sludge phase from at least one settling tank; and-filtering the oil phase through a depth filter for removing any possible remaining separation aids and impurities.)
1. A method for the purification of oil, the method comprising the steps of:
-providing at least one settling tank (21; 121a, 121b, 121 c) with a separation aid and oil to be purified;
-waiting to allow a sludge phase comprising the separation aid together with impurities from the oil to settle to a bottom portion (37) of the settling tank (21; 121a, 121b, 121 c);
-removing an oil phase excluding the sludge phase from the at least one settling tank; and
-filtering the oil phase through a depth filter for removing any possible remaining separation aids and impurities.
2. The method of claim 1, wherein the filtering is performed by adding cellulose fiber powder to a portion of the oil phase and circulating the portion of the oil phase on a carrier layer for building a depth filter, and wherein then the remaining portion of the oil phase is filtered through the depth filter.
3. The method according to any of the preceding claims, further comprising the step of mixing and warming the oil and separation aid when they are provided into the settling tank (21; 121a, 121b, 121 c).
4. The method of claim 3, further comprising: measuring the temperature of the contents in the settling tank (21; 121a, 121b, 121 c) in at least one location in the settling tank, and controlling the warming of the contents in the settling tank in dependence on the measured at least one temperature.
5. The method according to any one of the preceding claims, further comprising the step of warming the oil phase removed from the settling tank in a heating tank (47) prior to the step of filtering.
6. The method of any of the preceding claims, further comprising: the presence of an oil phase or sludge phase in at least one location in the settling tank is detected by at least one content detection sensor (55 a, 55b, 55 c; 155a, 155b, 155 c) arranged in the settling tank, and the removal of the oil phase is controlled in dependence on the detection, the control being performed by a control system (31; 131) connected to the sensors, pumps and valves in the system.
7. The method according to claim 6, wherein the step of detecting comprises detecting whether an oil phase or a sludge phase is present at substantially the level of the settling tank at which the oil phase outlet (39 a, 39 b; 139a, 139b, 139 c) is provided.
8. A method according to any one of the preceding claims, further comprising removing at least a portion of the sludge phase from the settling tank (21; 121a, 121b, 121 c) before another batch of contaminated oil to be purified is provided to the settling tank.
9. A method according to any of the preceding claims, wherein at least a part of the sludge phase precipitated in the bottom part (37) of the settling tank (21; 121a, 121b, 121 c) in a previous cleaning cycle performed in the settling tank is reused in a next cleaning cycle in which oil to be cleaned is provided to the settling tank, whereby the sludge phase is mixed into newly provided oil, possibly together with new separation aid, by means of a mixing device (33) arranged in the settling tank, the amount of new separation aid corresponding to the amount of removed separation aid in the sludge phase removed from the previous cleaning cycle.
10. The method according to any one of the preceding claims, wherein the method further comprises: the removal of sludge phase from the settling tank (21; 121a, 121b, 121 c) through at least one sludge phase outlet (41 a, 41 b; 141a, 141b, 141 c) is controlled while monitoring an output from a content detection sensor (55 b; 155a, 155b, 155 c) disposed at substantially the same level as an oil phase outlet (39 a; 139a, 139b, 139 c) of the settling tank, and the removal of sludge phase is stopped when the output from the content detection sensor indicates that an oil phase is provided at the level of the oil phase outlet instead of a previous sludge phase.
11. The method according to any of the preceding claims, comprising providing the oil to be purified to one settling tank (121 a, 121b, 121 c), while removing and filtering the oil phase from another settling tank (121 a, 121b, 121 c) that has been provided with the oil to be purified in the previous cycle of the purification process, while possibly also allowing the sludge phase to settle to the bottom part of a third settling tank (121 a, 121b, 121 c) that has been provided with the oil to be purified in the previous cycle of the purification process.
12. The method of any of the preceding claims, further comprising: -cyclically controlling the feeding of oil to be purified into and the removal of purified oil phase from at least two settling tanks (121 a, 121b, 121 c) arranged in the system, such that a continuous flow of oil into and out of the system is provided, said control being provided by a control system (131) arranged in the system connected to sensors, valves and pumps in the system.
13. A system (1; 101) for the purification of oil, the system comprising:
-at least one feed tank (3) comprising oil to be purified;
-a separation aid dosing device (13);
-at least one settling tank (21; 121a, 121b, 121 c), the at least one settling tank (21; 121a, 121b, 121 c) comprising at least one inlet (23; 123a, 123b, 123 c), the at least one inlet (23; 123a, 123b, 123 c) being connected to the at least one feed tank (3) for receiving oil to be purified and to the separation aid dosing device (13) for receiving separation aid, the settling tank (21; 121a, 121b, 121 c) further comprising at least one oil phase outlet (39 a, 39 b; 139a, 139b, 139 c) for removing an oil phase from the settling tank after settling of the sludge phase to a bottom portion (37) of the settling tank, the sludge phase comprising the separation aid together with impurities from the oil; and
-a filter module (51), the filter module (51) being connected to the at least one oil phase outlet (39 a, 39 b; 139a, 139b, 139 c) of the at least one settling tank (21; 121a, 121b, 121 c), wherein the filter module (51) comprises a depth filter.
14. The system of claim 13, wherein the depth filter is a filter capable of retaining impurities within the body structure of the filter media.
15. The system of claim 13 or 14, wherein the filter module (51) is configured for adding cellulose fiber powder to a portion of the oil phase and circulating the portion of the oil phase on a carrier layer for building the depth filter, and wherein the filter module (51) is further configured for filtering the remaining portion of the oil phase through the depth filter.
16. The system of any of claims 13-15, further comprising:
-a control system (31; 131), the control system (31; 131) being connected to sensors, pumps and valves in the system and configured for controlling the flow in the system in dependence of predetermined settings, sensor signals and possibly also user inputs.
17. The system of claim 16, wherein the at least one settling tank (21; 121a, 121b, 121 c) further comprises at least one content detection sensor (55 a, 55b, 55 c; 155a, 155b, 155 c) for detecting the presence of an oil phase or a sludge phase in at least one location in the settling tank, and wherein the control system (31; 131) is configured for controlling the removal of the oil phase from the settling tank in dependence on the detection.
18. The system of any one of claims 13-17, wherein the settling tank (21; 121a, 121b, 121 c) comprises a content detection sensor (55 b; 155a, 155b, 155 c), the content detection sensor (55 b; 155a, 155b, 155 c) being arranged in the settling tank at substantially the same level as an oil phase outlet (39 a; 139a, 139b, 139 c) of the settling tank, and the content detection sensor (55 b; 155a, 155b, 155 c) is configured for detecting whether an oil phase or a sludge phase is at that level in the settling tank.
19. The system according to any one of claims 13-18, further comprising at least one sludge tank (43; 143a, 143b, 143 c), the at least one sludge tank (43; 143a, 143b, 143 c) being connected to at least one sludge removal outlet (41 a, 41 b; 141a, 141b, 141 c) in the bottom portion (37) of the at least one settling tank (21; 121a, 121b, 121 c) and configured for receiving a sludge phase from the settling tank.
20. The system of claim 19, wherein the settling tank (21) comprises at least two sludge removal outlets (41 a, 41 b) arranged at different liquid levels in the bottom portion (37) of the settling tank, both of the at least two sludge removal outlets (41 a, 41 b) being connected to the at least one sludge tank (43).
21. The system according to any one of claims 13-20, wherein the at least one settling tank (21; 121a, 121b, 121 c) further comprises a mixing device (33), at least one temperature sensor (57 a, 57 b) and at least one heating device (35), the at least one heating device (35) being configured for heating the contents of the settling tank in dependence of the temperature measured by the at least one temperature sensor.
22. The system according to any one of claims 13-21, wherein the system further comprises a heating tank (47) arranged between the at least one oil phase outlet (39 a, 39 b) of the at least one settling tank (21) and the filter module (51).
23. The system according to any one of claims 13-22, wherein a control system (31; 131) provided in the system (1; 101) is configured for: controlling removal of sludge phase from the settling tank (21; 121a, 121b, 121 c) through the at least one sludge phase outlet (41 a, 41 b; 141a, 141b, 141 c) while monitoring output from a content detection sensor (55 b; 155a, 155b, 155 c) disposed at substantially the same level as an oil phase outlet (39 a; 139a, 139b, 139 c) of the settling tank, and stopping removal of sludge phase when output from the content detection sensor (55 b; 155a, 155b, 155 c) indicates that an oil phase is provided at the level of the oil phase outlet (39 a; 139a, 139b, 139 c) instead of a previous sludge phase.
24. A system according to any one of claims 13-23, further comprising at least two settling tanks (121 a, 121b, 121 c) connected in parallel in the system (101).
25. A system according to claim 24, wherein the system comprises a control system (131), the control system (131) being connected to sensors, pumps and valves of the system (101) and being configured for controlling the feeding of oil to be purified into the at least two settling tanks (121 a, 121b, 121 c) and the removal of oil phase from the at least two settling tanks, such that one settling tank is receiving oil to be purified while the oil phase is being removed from another settling tank and possibly while a settling process is being performed in a third settling tank.
26. A computer program product comprising instructions which, when executed in a processor (32; 132) in a control system (31; 131) in a system (1; 101) for purification of oil, cause the control system (31; 131) to carry out the method according to any one of claims 1-12.
Technical Field
The present invention relates to a method and a system for the purification of oil.
Background
The purification of contaminated oil, such as for example mineral oil, industrial oil, process oil or hydraulic oil, is important for the possibility of reusing the oil and is therefore an important factor for the future environment and the limited natural resources of the oil. Contaminated oil can be purified or recovered by means of a liquid two-phase separation process, wherein a liquid separation aid is added to and mixed with the oil. The impurities will be captured by the separation aid and will accumulate in the bottom phase. There is still a need to improve the purification process for contaminated oils.
Disclosure of Invention
It is an object of the present invention to provide an improved method and system for the purification of oil.
This is achieved in a method and a system and a computer program according to the independent claims.
Thereby, by filtering the oil phase after settling, any possible remaining separation aids and impurities in the oil can be removed and an improved purification of the oil is achieved.
In one aspect of the invention, a method for purification of oil is provided. The method comprises the following steps:
-providing a separation aid and the oil to be purified to at least one settling tank;
-waiting to allow a sludge phase to settle to the bottom part of the settling tank, said sludge phase comprising separation aids together with impurities from the oil;
-removing an oil phase excluding the sludge phase from at least one settling tank; and
-filtering the oil phase through a depth filter for removing any possible remaining separation aids and impurities.
In another aspect of the invention, a system for purification of oil is provided. The system comprises:
-at least one feed tank comprising oil to be purified;
-a separation aid dosing device;
-at least one settling tank comprising at least one inlet connected to at least one feed tank for receiving oil to be purified and to a separation aid dosing device for receiving separation aid, the settling tank further comprising at least one oil phase outlet for removing oil phase from the settling tank after settling of a sludge phase to a bottom part of the settling tank, the sludge phase comprising separation aid together with impurities from the oil; and
-a filter module connected to the oil phase outlet of the at least one settling tank, wherein the filter module comprises a depth filter.
In yet another aspect of the invention, a computer program product is provided. The computer program comprises instructions which, when executed in a processor in a control system in a system for purification of oil, cause the control system to carry out the method according to the invention.
In this way, very small impurity particles in the oil can also be effectively filtered out of the oil phase. The combination of the depth filter and any remaining separation aid to be captured in the depth filter will increase the efficiency of removing small impurity particles. Unlike conventional thin layer surface filters, which are filtered only at the surface, depth filters are filters that are capable of retaining impurities within the body structure of the filter media. The depth filter will absorb any remaining separation aid and contaminants and the absorbed separation aid will also be able to catch small contaminant particles from the oil and thereby increase the filter efficiency.
In one embodiment of the invention, the filtration is performed by adding cellulose fiber powder to a portion of the oil phase and circulating the portion of the oil phase on a carrier layer for building a depth filter (also called filter cake), and wherein then the remaining portion of the oil phase is filtered through the depth filter. The filter module is also configured for such type of filtering. Hereby a very efficient, flexible, easy and cost-effective depth filtration is achieved. Depth filters are prone to change between batches of oil to be purified and depth filters of this type are very effective for the removal of small particles. Furthermore, automation of the process can be easily achieved for both the construction of the filter cake and the change of the filter. Further, the size of the depth filter, i.e., the depth can be changed very easily according to circumstances simply by employing the amount of the cellulose fiber powder added.
In one embodiment of the invention, the method further comprises the step of mixing and warming the oil and the separation aid when they are provided to the settling tank.
In one embodiment of the invention, the at least one settling tank further comprises a mixing device, at least one temperature sensor and at least one heating device configured for heating the contents of the settling tank in dependence of the temperature measured by the at least one temperature sensor.
This can improve the separation efficiency.
In one embodiment of the invention, the method further comprises: the temperature of the contents of the settler in at least one location in the settler is measured and the warming of the contents of the settler is controlled in dependence on said measured at least one temperature.
In one embodiment of the invention, the method further comprises the step of warming the oil phase removed from the settling tank in a heating tank prior to the step of filtering. Whereby the filtering can be more efficient.
In one embodiment of the invention, the method further comprises: the presence of an oil phase or sludge phase in at least one location in the settling tank is detected by at least one content detection sensor arranged in the tank, and the removal of the oil phase is controlled in dependence on said detection, said control being performed by a control system connected to the sensors, pumps and valves in the system. Whereby it can be ensured that only the oil phase is removed through the oil phase outlet.
In one embodiment of the invention, the step of detecting comprises detecting whether the oil phase or the sludge phase is substantially at a level in the settling tank at which the oil phase outlet is provided.
In one embodiment of the invention, the method further comprises removing at least a portion of the sludge phase from the settling tank before another batch of contaminated oil to be purified is provided to the settling tank.
In one embodiment of the invention, at least a part of the sludge phase precipitated in the bottom part of the settling tank in a previous cleaning cycle performed in the settling tank is reused in a next cleaning cycle in which the oil to be cleaned is supplied to the settling tank, whereby the sludge phase is mixed into the newly supplied oil, possibly together with a new separation aid by means of a mixing device arranged in the settling tank, the amount of the new separation aid corresponding to the amount of removed separation aid in the sludge phase removed from the previous cleaning cycle. The reuse of separation aids is economically beneficial and in this way also larger amounts of separation aids can be used for each cleaning cycle. This will improve the purification efficiency.
In one embodiment of the invention, the method further comprises: the method comprises controlling removal of a sludge phase from the settling tank through at least one sludge phase outlet while monitoring an output from a content detection sensor disposed at substantially the same level as an oil phase outlet of the settling tank, and stopping removal of the sludge phase when the output from the content detection sensor indicates that an oil phase is provided at the level of the oil phase outlet instead of a previous sludge phase. Thereby, the position of the intermediate phase between the oil phase and the sludge phase can be controlled and it can be ensured that only the oil phase is removed from the settling tank through the oil phase outlet.
In one embodiment of the invention, the method further comprises providing the oil to be purified to one settling tank while removing and filtering oil phase from another settling tank that has been provided with the oil to be purified in a previous cycle of the purification process, while possibly also allowing the sludge phase to settle to a bottom part of a third settling tank that has been provided with the oil to be purified in a previous cycle of the purification process.
In one embodiment of the invention, the method further comprises: cyclically controlling the feeding of oil to be purified to and the removal of purified oil phase from at least two settling tanks provided in the system so as to provide a continuous flow of oil into and out of the system, said control being provided by a control system provided in the system connected to sensors, valves and pumps in the system.
Thereby, the oil to be purified can be continuously provided into the system and the purified oil phase can be continuously removed from the system. Whereby the system can be used as an on-line system for continuous purification of oil.
In one embodiment of the invention, the system further comprises:
a control system connected to the sensors, pumps and valves in the system and configured for controlling the flow in the system in dependence of predetermined settings, sensor signals and possibly also user inputs.
In one embodiment of the invention, the at least one settling tank further comprises at least one content detection sensor for detecting the presence of an oil phase or a sludge phase in at least one location in the settling tank, and wherein the control system is configured for controlling the removal of the oil phase from the settling tank in dependence on said detection.
In one embodiment of the invention, the settling tank comprises a content detection sensor arranged at substantially the same level in the settling tank as the oil phase outlet of the settling tank, and the content detection sensor is configured to detect whether the oil phase or the sludge phase is at that level in the settling tank. Whereby it can be ensured that only the oil phase is removed through the oil phase outlet.
In one embodiment of the invention, the system further comprises at least one sludge tank connected to the at least one sludge removal outlet in the bottom part of the at least one settling tank and configured for receiving a sludge phase from the settling tank.
In one embodiment of the invention, the settling tank comprises at least two sludge removal outlets arranged at different liquid levels in the bottom portion of the settling tank, both being connected to the at least one sludge tank. Whereby the user can select which part of the sludge phase he wishes to remove and which part he wishes to keep in the tank for re-use. For example the bottommost portion of the sludge phase can be retained for reuse. Whereby the heavier part of the sludge phase can be kept in a tank for re-use and the lighter part of the sludge phase will be removed.
In one embodiment of the invention, the system further comprises a heating tank arranged between the oil phase outlet of the at least one settling tank and the filter module.
In one embodiment of the invention, a control system provided in the system is configured to: controlling removal of the sludge phase from the settling tank through the at least one sludge phase outlet while monitoring an output from a content detection sensor disposed at substantially the same level as the oil phase outlet of the settling tank, and stopping removal of the sludge phase when the output from the sensor indicates that an oil phase is provided at the level of the oil phase outlet instead of the previous sludge phase.
In one embodiment of the invention, the system further comprises at least two settling tanks connected in parallel in the system.
In one embodiment of the invention, the system comprises a control system connected to the sensors, pumps and valves of the system and configured for controlling the feeding of the oil to be purified into the at least two settling tanks and the removal of the oil phase from the at least two settling tanks, such that one settling tank is receiving the oil to be purified while the oil phase is being removed from the other settling tank and possibly while the settling process is being performed in the third settling tank.
Drawings
Fig. 1 schematically shows a system for the purification of oil according to one embodiment of the invention.
Fig. 2 schematically shows a system for the purification of oil according to another embodiment of the invention, comprising three parallel settling tanks.
Fig. 3 is a flow diagram of a method according to an embodiment of the invention.
Detailed Description
Fig. 1 schematically shows a system 1 for the purification of oil according to one embodiment of the invention. The system 1 comprises a
The separation aid will absorb the contaminating solids or dissolved impurities in the contaminated target oil through chemical interactions. The separation aid should be liquid at the temperature at which the process is carried out. The separation aid composition should be substantially insoluble in the contaminated target oil so as to form a two-phase mixture when mixed with the contaminated oil. The liquid separation aid should also have a density different from the density of the contaminated oil to be purified.
The separation aid is insoluble in the contaminated target oil due to its polar nature and therefore the colloid consisting of small droplets of the liquid separation aid composition is formed by stirring, which can absorb unwanted solids or dissolved impurities in the contaminated target oil through chemical interactions (hydrophilic, hydrophobic and charge interactions). In case the separation aid has a higher density than the oil, the separation aid will form a lower phase together with the solids and/or dissolved impurities under gravity separation. In case the separation aid has a lower density than the contaminated target oil, it will form an upper phase upon gravity separation.
The liquid separation aid used in the present invention will generally be composed on the basis of the following components: a) a polar polymer; b) hydrotrope/solubilizer; and, c) a co-surfactant (co-tenside).
Suitable separation aids having the properties described above that can be used in the process of the present invention may, for example, constitute a composition comprising a mixture of a polar polymer (such as polyethylene glycol, polypropylene glycol or similar polyalkylene glycols) and an organic surface-active ingredient having nonionic, anionic, cationic and amphoteric properties and having the ability to enhance the solubility of solid or dissolved impurities in the separation aid.
One example of a separation aid that can be used in the present invention includes: a) at least one polar polymer insoluble in the oil and having a higher density than the oil, such as polyethylene glycol, having an average molecular weight of 190-; b) at least one surface active hydrotrope/solubilizer, such AS an anionic sulphonic acid, phosphate based species or a non-ionic surfactant of the polyglycoside family, such AS Simulsol SL 4, Simulsol SL 7G and Simulsol AS 48 (Seppic, Air Liquide group); c) at least one amphoteric co-surfactant, such as the propionate type, for example, Ampholak YJH-40 (Akzo Nobel), sodium caprylocamido dipropionate.
The system 1 of the invention also comprises at least one
The method according to the invention provides oil to be purified and separation aid from the
The settling
According to the invention, the
A depth filter can be particularly suitable for the filtration step according to the invention. Unlike surface-only filtration as in conventional thin-layer surface filters, depth filters are filters that retain impurities within the body structure of the filter media. The advantage of deep filtration is a high dirt holding capacity without being blocked by a large total filter mass. The use of cellulose fiber powder as filter medium enables the absorption and removal of polar liquid separation aids and water together with solid particles. By reducing the filtration rate, the contact time will be increased to provide high separation efficiency.
In one embodiment of the invention, the
One example of a depth filter that can be used in the present invention is a depth filter built for each batch of oil phase to be purified. The cellulose fiber powder is mixed into a first small amount of the oil phase to be purified. This mixing of the cellulose fibre powder and the oil phase is then passed through the carrier layer a number of times, for example with disposable carrier paper or with a reusable carrier layer material. In this way, depth filters (also referred to as filter cakes) made of these cellulose fibers are built up on the carrier layer. When the depth filter has been constructed, the remainder of the oil phase passes through the depth filter. Any remaining separation aid will be captured by the depth filter. Furthermore, by means of the separation aid which has been absorbed in the depth filter, other remaining impurities in the oil phase will be captured by the depth filter and even the smallest micro-and nano-sized particles will be captured to a large extent by means of the separation aid which has been absorbed in the depth filter as explained above. The forcing of the oil phase through the depth filter can be provided in different ways, for example by providing pressure from above the carrier layer or vacuum from below the carrier layer. After filtering a batch of oil phase, the depth filter can be discarded and a new depth filter can be provided by the same process as described above. Depth filters of this type, which use cellulose fiber powder for the construction of depth filters, are very cost-effective types of filtration. Furthermore, it is a very flexible filtration method, since the thickness of the filter can easily be adjusted from time to time by changing the amount of cellulose fiber powder added to build the filter. It is also very easy to change the filter from time to time (e.g. between each batch of oil phase to be purified), and both this change of filter and the process for building the filter can easily be provided as an automated process.
Tests have been performed for measuring the effect of filtration using depth filters in combination with the purification method using the separation aid described above. From these tests it is clear that small capture particles are very effectively removed by this method. Details are given from the following three example tests:
1. the hydraulic mineral oil (Fuchs/Statoil Hydraway HVXA 68), which has been used in hydraulic paper balers, was cleaned both by a conventional klentek electrostatic filter and by the method according to the invention and the particle content of the cleaned oil was measured according to ISO specification 4406:99, wherein the particle capture >4 μm/>6 μm/>14 μm. The result of the conventional cleaning is 18/17/13 and the result of the cleaning according to the invention is: 14/13/10.
2. The synthetic gearbox oil (ExxonMobil mobil gear XMP 320) which has been used in wind power plant gearboxes and the particle content of the cleaned oil was measured according to ISO specification 4406:99, wherein the particle capture >4 μm/>6 μm/>14 μm, was cleaned both by the conventional c.c. JENSEN
3. Mineral metal cutting oil (Castrol Honilo 981), which has been used in cylinder honing processes and the particle content of the cleaned oil was measured according to ISO specification 4406:99, was cleaned both by a conventional TRANSORFILTER Backflush paper filter rod of 1 μm and by the method according to the invention, wherein the particle capture >4 μm/>6 μm/>14 μm. The result of the conventional cleaning is 25/29/19 and the result of the cleaning according to the invention is: 13/11/9.
In this embodiment, the settling
The
The settling
The
Further, a computer program product is provided. The computer program comprises instructions which, when executed in the
-providing a separation aid and the oil to be purified to at least one settling tank;
-waiting to allow a sludge phase to settle to the bottom of the settling tank, said sludge phase comprising separation aids together with impurities from the oil;
-removing an oil phase excluding the sludge phase from at least one settling tank; and
-filtering the oil phase for removing any possible remaining separation aids and impurities.
The computer program further optionally comprises instructions that, when executed in the
-mixing and warming the oil and the separation aid when they are supplied to the settling tank; and/or
-controlling a system to measure the temperature of the contents in the settler in at least one location in the settler and to control the warming of the contents in the settler in dependence on said measured at least one temperature; and/or
-warming the oil phase removed from the settling tank in a heating tank before the step of filtering; and/or
-detecting the presence of an oil or sludge phase in at least one location in the settling tank by means of a content detection sensor arranged in the tank, and controlling the removal of the oil phase in dependence of said detection, said control being performed by a control system connected to the sensors, pumps and valves in the system; and/or
-removing at least a part of the sludge phase from the settling tank before another batch of contaminated oil to be purified is provided to the settling tank; and/or
At least a part of the sludge phase precipitated in the bottom part of the settling tank in a previous cleaning cycle performed in the settling tank is reused in a next cleaning cycle in which the oil to be cleaned is supplied to the settling tank, whereby the sludge phase is mixed into the newly supplied oil, possibly together with a new separation aid by means of a mixing device arranged in the settling tank, the amount of the new separation aid corresponding to the amount of removed separation aid in the sludge phase removed from the previous cleaning cycle.
Fig. 2 schematically shows a
The
The
Fig. 3 is a flow diagram of a method according to an embodiment of the invention. The steps of the method are described in order below:
s1: to at least one
S3: waiting to allow the sludge phase to settle to the settling
S5: from at least one
S7: the oil phase is filtered through a depth filter for removing any possible remaining separation aids and impurities. The filtration is performed in a
The method can also optionally comprise one or more of the following method steps:
-mixing and warming the oil and the separation aid when they are supplied to the settling tank;
-measuring the temperature of the contents in the settler in at least one location in the settler and controlling the warming of the contents in the settler in dependence on said measured at least one temperature;
-warming the oil phase removed from the settling tank in a heating tank before the step of filtering;
by means of a content sensor 55 arranged in the settling tank; 55a, 55b, 55c to detect the presence of a liquid in the
-removing at least a part of the sludge phase from the settling tank before another batch of contaminated oil to be purified is provided to the settling tank; and/or
At least a part of the sludge phase precipitated in the bottom part of the settling tank in a previous cleaning cycle performed in the settling tank is reused in a next cleaning cycle in which the oil to be cleaned is supplied to the settling tank, whereby the sludge phase is mixed into the newly supplied oil, possibly together with a new separation aid by means of a mixing device arranged in the settling tank, the amount of the new separation aid corresponding to the amount of removed separation aid in the sludge phase removed from the previous cleaning cycle.
In one embodiment of the invention the filtration is performed by adding cellulose fibre powder to a part of the oil phase and circulating the part of the oil phase on a carrier layer for building a depth filter, and wherein then the remaining part of the oil phase is filtered through the depth filter.
In one embodiment of the invention, the method further comprises: the monitoring is carried out from a settling
In one embodiment of the invention, the method further comprises: the oil to be purified is supplied to one
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