Apparatus and process for separating asphaltenes from an oil-containing fuel

Abstract

An apparatus for separation of asphaltenes from an oil-containing fuel, has a mixing element for intensive mixing of the oil-containing fuel with a solvent to form a solution supersaturated with asphaltenes, a vessel for reducing the oversaturation by depositing the asphaltenes out of the supersaturated solution, a growth zone formed within the vessel for growth of asphaltene particles present via the asphaltenes separated out of the supersaturated solution, and a classifying unit connected in terms of flow to the vessel for separation of the asphaltene particles grown in the growth zone in terms of their particle size, wherein the vessel is formed and set up such that a stream containing asphaltene particles circulates between the mixing element and the growth zone of the vessel. A corresponding process has a stream containing asphaltene particles that circulates between the mixing element and the growth zone of the vessel.

Claims

1. An apparatus for the separation of asphaltenes from an oil-containing fuel, comprising: a mixing element for intensive mixing of the oil-containing fuel with a solvent to form a solution supersaturated with asphaltenes, a vessel for reducing the supersaturation by precipitating the asphaltenes from the supersaturated solution, a growth zone formed inside the vessel for growth of asphaltene particles present via the asphaltenes separated from the supersaturated solution, and a classifying device fluidically connected to the vessel for separation of the asphaltene particles grown in the growth zone according to their particle size, wherein the classifying device comprises a first separation stage for separating large asphaltene particles from a first partial stream, and wherein the classifying device comprises a second separation stage for separating small asphaltene particles from a second partial stream, wherein the vessel is designed and configured such that a stream containing asphaltene particles circulates between the mixing element and the growth zone of the vessel.

2. The apparatus as claimed in claim 1, wherein the vessel for circulation of the stream containing asphaltene particles is fluidically connected to the mixing element.

3. The apparatus as claimed in claim 1, wherein the mixing element is fluidically connected to a supply line of the vessel via a discharge line.

4. The apparatus as claimed in claim 1, wherein the vessel is fluidically connected to a supply line of the mixing element via a return line.

5. The apparatus as claimed in claim 1, wherein the mixing element is arranged inside the vessel.

6. The apparatus as claimed in claim 1, wherein the vessel is fluidically connected to a supply line of the first separation stage via a first discharge line in order to supply the first partial stream to the first separation stage.

7. The apparatus as claimed in claim 1, wherein the first separation stage is fluidically connected to a supply line of the vessel via a return line in order to recycle a first return flow enriched with asphaltene particles remaining after the large asphaltene particles are separated.

8. The apparatus as claimed in claim 1, wherein the first separation stage is fluidically connected upstream of a treatment device.

9. The apparatus as claimed in claim 1, wherein the vessel is fluidically connected to a supply line of the second separation stage via a second discharge line in order to supply the second partial stream to the second separation stage.

10. The apparatus as claimed in claim 9, wherein the second discharge line of the vessel is arranged at the top thereof.

11. The apparatus as claimed in claim 1, wherein the second separation stage is connected to a supply line of the vessel via a return line in order to recycle a second return flow enriched with the small asphaltene particles.

12. The apparatus as claimed in claim 1, wherein the second separation stage is fluidically connected downstream of a treatment device.

13. The apparatus as claimed in claim 1, wherein the vessel comprises a classifying zone for the separation of the asphaltene particles according to their particle size.

14. A process for the separation of asphaltenes from an oil-containing fuel, comprising: mixing the oil-containing fuel intensively with a solvent by a mixing element, wherein a solution supersaturated with asphaltenes is formed during the mixing process, wherein the supersaturation is decreased by precipitating the asphaltenes from the supersaturated solution in a vessel, wherein asphaltene particles present in a growth zone of the vessel grow via asphaltenes precipitated from the supersaturated solution, separating the asphaltene particles grown in the growth zone by a classifying device according to their particle size, wherein a first partial stream is supplied to a first separation stage of the classifying device in order to separate large asphaltene particles, and wherein a second partial stream is supplied to a second separation stage of the classifying device for the separation of small asphaltene particles, and wherein a stream containing asphaltene particles circulates between the growth zone of the vessel and the mixing element.

15. The process as claimed in claim 14, wherein the stream containing asphaltene particles flows from the vessel into the mixing element.

16. The process as claimed in claim 14, wherein the stream containing asphaltene particles is mixed in the mixing element with the oil-containing fuel and the solvent.

17. The process as claimed in claim 16, wherein a stream containing the asphaltene particles, the oil-containing fuel, and the solvent is supplied to the vessel.

18. The process as claimed in claim 14, wherein the oil-containing fuel and the solvent are mixed inside the vessel.

19. The process as claimed in claim 14, wherein the first partial stream is withdrawn from the vessel at the bottom thereof.

20. The process as claimed in claim 14, wherein a first return flow enriched with asphaltene particles remaining after the large asphaltene particles are separated is supplied to the vessel.

21. The process as claimed in claim 14, wherein the large asphaltene particles separated from the first partial stream are supplied to a treatment device.

22. The process as claimed in claim 14, wherein the second partial stream is withdrawn from the vessel at the top thereof.

23. The process as claimed in claim 14, wherein a second return flow enriched with the small asphaltene particles is supplied to the vessel.

24. The process as claimed in claim 14, wherein an outlet stream depleted of small asphaltene particles is supplied to a treatment device.

25. The process as claimed in claim 14, wherein the asphaltene particles are separated according to their particle size inside a classifying zone of the vessel.

26. The apparatus as claimed in claim 8, wherein the large asphaltene particles separated from the first partial stream are supplied to the treatment device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, examples of the invention will be explained in further detail with reference to a drawing. The figures are as follows:

(2) FIG. 1 shows an apparatus for the separation of asphaltenes from an oil-containing fuel with a container fluidically connected to a mixing element, and

(3) FIG. 2 shows a further apparatus for the separation of asphaltenes from an oil-containing fuel with a mixing element arranged inside a vessel.

DETAILED DESCRIPTION OF INVENTION

(4) FIG. 1 shows an apparatus 1 for the separation of asphaltenes from an oil-containing fuel 3. A heavy oil is used as a fuel 3. Together with pentane as a solvent 5, the heavy oil 3 is supplied via corresponding supply lines 7, 9 to a mixing element 11 configured as a mixing pump. Inside the mixing element 11, the heavy oil 3 and the solvent 5 are subjected to ultra-rapid mixing.

(5) Rapid mixing gives rise to a metastable, supersaturated solution, thus avoiding the formation of a phase interface between the heavy oil 3 and the pentane 5 and preventing premature precipitation of asphaltene particles during the mixing process.

(6) The resulting mixture 13 is supplied to a vessel 15 fluidically connected to the mixing element 11, for which purpose the mixing element 11 is fluidically connected via a discharge line 17 to a supply line 19 of the vessel 15. The precipitation process of the asphaltenes already begins on supply to the vessel 15, i.e. after completion of the mixing process. The asphaltenes precipitating from the solution are deposited on asphaltene particles already present in the process.

(7) Inside the vessel 15 is a growth zone 23 in which the asphaltene particles grow. The solid enrichment inside the vessel 15 required for the separation following this growth is ensured by means of a sufficiently long residence time of the asphaltene particles in the vessel 15. The longer the residence time of the asphaltene particles, the higher the precipitation rate, and thus, because of the improved separation of the particles, the higher the cleaning efficiency of the separating apparatus 1 used as well.

(8) The vessel 15 is fluidically connected to a classifying device 25 for separation of the asphaltene particles that have grown in the growth zone 23 according to their particle size.

(9) For this purpose, the classifying device 25 comprises two separation stages 27, 29. The coupling of the first separation stage 27 to the vessel is carried out via the connection of a first discharge line 31 of the vessel 15 to a supply line 33 of the first separation stage 27. Via the lines 31, 33, a first partial stream 35 is supplied to the first separation stage 27. The discharge line 31 of the vessel 15 is attached to the bottom 37 thereof.

(10) In the first separation stage 27, which is configured as a hydrocyclone, large asphaltene particles 39 that exceed a predetermined separating grain size of 25 m are removed from the process. They are supplied via a discharge line 41 to a treatment device 43 and can then be supplied for a further use, for example in road construction.

(11) The separation of the large asphaltene particles 39 gives rise to a solution which is recycled to the vessel 15 as a first return flow 45. The first return flow 45 now contains only asphaltene particles having an average diameter of less than 25 m. For recycling of the return flow 45, i.e. the partial stream depleted of large asphaltene particles, the first separation stage 27 is connected to a return line 47 that is in turn fluidically connected to a supply line 49 of the vessel 15. The asphaltene particles still contained in the return flow 45 serve as growth nuclei inside the vessel 15 or inside the growth zone 23 of the vessel.

(12) The second separation stage 29 of the classifying device 25 is used for the separation of small asphaltene particles 51 from a second partial stream 53. For the supply of the second partial stream 53 to the second separation stage 29, the vessel 15 is fluidically connected via a second discharge line 55 to a supply line 57 of the second separation stage 29. The second discharge line 55 of the vessel is arranged at the top 59 thereof.

(13) The second partial stream 53 essentially comprises small asphaltene particles 51 that are to be kept in the process so that they can continue to grow during the process. Accordingly, in the second separation stage 29, which is also configured as a hydrocyclone, asphaltene particles 51 with an average diameter of greater than 5 m are separated from the liquid and returned to the vessel 15. Recycling of the second return flow 61 enriched with small asphaltene particles 51 takes place via a connection of a return line 63 of the second separation stage 29 to a supply line 65 of the vessel 15.

(14) Furthermore, a treatment device 67 is also fluidically connected to the second separation stage 29. The outlet stream 71 generated on separation of the asphaltene particles 51, i.e. a clear stream, is supplied to the treatment device 67 via a discharge line 69 connected to the second separation stage 29. Inside the treatment device 67, the solvent 5 can be recovered and again supplied to the mixing element 11.

(15) Asphaltene particles 73 with an average diameter in the range of 5 m to 25 m that can be moved in a circuit 75 are present inside the vessel 15 during the process. A partial stream 79 with these asphaltene particles 73 is supplied to the mixing element 11 via a return line 77 connected to the container 15.

(16) For this purpose, the return line 77 of the vessel 15 is connected to a supply line 81 of the mixing element 11. Thus, in addition to the supply line 7 for the heavy oil 3 and the supply line 9 for pentane 5, the supply line 81 is also connected to the mixing element 11, with the line ensuring the supply or the circulation of growth nuclei for the asphaltene precipitation.

(17) Because of the asphaltene particles 73 contained in the circulating partial stream 79, growth nuclei for the asphaltenes are already available at the time of mixing of the oil-containing fuel 3 and the solvent 5. The asphaltenes contained in the supersaturated solution, i.e. the mixture 13, precipitate only on the asphaltene particles 73 already present and grow thereon. In other words, the precipitation, which essentially takes place after mixing of the oil-containing fuel 3 and the solvent 5, is selectively controlled by the circulation of the asphaltene particles between the mixing element 11 and the growth zone 23 of the vessel 15.

(18) Inside the vessel 15, moreover, a classifying zone 83 can be configured which, alternatively or additionally to the first separation stage 27, separates large asphaltene particles. The position of the classifying zone 83 inside the vessel 15 is in this case indicated by an arrow.

(19) FIG. 2 shows a further apparatus 91 that also serves to separate asphaltenes from an oil-containing fuel 3 using a solvent 93, in this case hexane.

(20) The structural difference between the apparatus 91 and the apparatus 1 according to FIG. 1 lies in the fact that the mixing element 95 used is not installed upstream of the vessel 97, as is the case in apparatus 1, but instead is arranged inside the vessel 97.

(21) In the arrangement of the mixing element 95 inside the vessel 97, the heavy oil 3 and the solvent 93, or the anti-solvent with respect to the asphaltenes contained in the oil-containing fuel 3, are metered via supply lines 99, 101 directly into the vessel 97. The mixing takes place inside the vessel 97 in a mixing zone 105 configured on the wall 103 of the vessel by means of the mixing element 95 configured as an internal mixing pump immediately on entry of the heavy oil 3 and the solvent 93. The mixing element 95 ensures the necessary ultra-rapid mixing of the two components 3, 93.

(22) The mixture 109 resulting from mixing flows through a suitable flow control inside the vessel 95 into the growth zone 111 of the vessel 95, where the asphaltenes precipitate or the already precipitated asphaltene particles continue to grow. In this case as well, asphaltene particles 113 of average size already present in the vessel 95 are available to them as growth nuclei.

(23) Because of the flow control, a partial stream 115 containing asphaltene particles 113 also circulates between the element 95 and the growth zone 111. As growth nuclei, the asphaltene particles 113 provide a surface that promotes the precipitation of asphaltenes and at the same time prevents deposition-related fouling of walls, pipelines or the like of an apparatus 1 used correspondingly for deasphalting.

(24) As in FIG. 1 as well, the vessel 97 can be configured with a classifying zone 117, the position of which is indicated by an arrow, which alternatively or additionally serves as the separation stage 27 for the classification of large asphaltene particles.

(25) With respect to the function of the further apparatus components comprised by the apparatus 91, the detailed description of the apparatus 1 according to FIG. 1 can be applied to the apparatus 91 according to FIG. 2.