Solvent deasphalting extraction tower

Abstract

The invention discloses a solvent deasphalting extraction tower, which at least comprises: a tower body, which is internally provided with a heating settling section, an extraction section and a deoiled asphalt collection area in sequence from top to bottom; separating out asphaltene and colloid from the extracted deasphalted oil solution in a heating settling section, and settling downwards; the property of a heat exchange medium used in the heat exchange tube is the same as that of a solvent used for deasphalting in the tower body, and the temperature of the solvent used as the heat exchange medium is higher than that of the solvent used for deasphalting in the tower body. According to the invention, the heat exchange medium is replaced by the heated solvent, so that the heat exchange requirement of the top of the extraction tower can be met, the problem that the discharged material of the extraction tower carries the existing heat exchange medium such as steam or conduction oil can be effectively avoided, and meanwhile, the solvent after heat exchange can enter the extraction tower to be used as a deasphalting solvent after temperature control.

Description

Technical Field

[0001] The present invention relates to the technical field of solvent deasphalting, and particularly to a solvent deasphalting extraction tower using a solvent as a heat exchange medium. Background Art

[0002] Solvent deasphalting refers to a petroleum product refining process that uses an extraction method to remove gums and asphalt from vacuum residue (or atmospheric residue) obtained from crude oil distillation, and produces petroleum asphalt while producing deasphalted oil. Under the conditions of vacuum distillation, some high-viscosity lubricating oil components in paraffinic or intermediate-base crude oil cannot be vaporized due to their very high boiling points and remain in the vacuum residue. They are separated by utilizing the difference in their solubility in the solvent between gums and asphalt. Commonly used solvents are propane, butane, pentane, hexane, or a mixture of propane and butane.

[0003] For example, Chinese Patent Application CN112680242A discloses an inner member at the top of an extraction tower, an extraction tower, and a solvent deasphalting extraction method. The inner member in this solution includes coalescing packing disposed in the extraction tower and cooperating with the inner wall of the extraction tower, and a heat exchange tube system uniformly distributed in the coalescing packing. Among them, the heat exchange tube system includes a heat exchange medium inlet, a heat exchange main pipe, heat exchange branch pipes, and a heat exchange medium outlet that are sequentially connected. The heat exchange branch pipes are multiple heat exchange tubes connected in parallel or in series and are in close contact with the coalescing packing; the heat exchange medium inlet and the heat exchange medium outlet are disposed on the tower wall of the extraction tower. This solution can improve the extraction efficiency and heat transfer effect and prevent the entrainment of asphaltenes.

[0004] However, in existing solvent deasphalting technologies similar to the above, in order to reduce the amount of deoiled asphalt entrained in the top discharge of the extraction tower, a heater is generally provided at the top of the extraction tower to reduce the content of gums and asphaltenes in the deasphalted oil at the top of the tower by heating. The heating part at the top of the extraction tower uses a heating form of a heat exchange medium (steam, heat-conducting oil, etc.) in cooperation with heat exchange tubes. With this heating method, when the heat exchange tube ruptures, the heat exchange medium will mix with the raw materials in the extraction tower, resulting in the problem of entraining the heat exchange medium in the extraction tower discharge, reducing the product quality, and increasing the complexity of subsequent separation.

[0005] Therefore, there is an urgent need for a solvent deasphalting extraction tower that can meet the heat exchange requirements and will not cause the problem of entraining the heat exchange medium in the extraction tower discharge when the heat exchange tube ruptures.

[0006] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the present invention and should not be regarded as an admission or any form of suggestion that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0007] The object of the present invention is to provide a solvent deasphalting extraction column. By replacing the heat exchange medium with heated solvent, it can not only meet the heat exchange requirements at the top of the extraction column, but also effectively avoid the problems of the existing heat exchange media such as the extraction column discharge entraining steam or heat transfer oil. At the same time, the heated solvent after heat exchange can enter the extraction column as the deasphalting solvent after temperature control.

[0008] Another object of the present invention is to provide a solvent deasphalting extraction column. By using the heated solvent as the heat exchange medium and the heated solvent as the heat tracing and insulation medium of the extraction column, the energy consumption of the device can be effectively reduced.

[0009] Another object of the present invention is to provide a solvent deasphalting extraction column. By using the heated solvent as the heat exchange medium and the heat exchange tubes penetrate the packing layer, the heated solvent can not only be fully utilized, but also optimize the distribution of the solvent in the extraction column below the heat exchange tubes to avoid local solvent overdose.

[0010] To achieve the above object, the present invention provides a solvent deasphalting extraction column, which at least includes: a tower body, in which a heating and settling section, an extraction section and a deoiled asphalt collection area are successively arranged from top to bottom; the deasphalted oil solution after extraction precipitates asphaltenes and resins in the heating and settling section and settles downward; heat exchange tubes, in which the heat exchange medium used is the same as the solvent used for deasphalting in the tower body, and the temperature of the solvent used as the heat exchange medium is higher than the temperature of the solvent used for deasphalting in the tower body.

[0011] Further, in the above technical solution, the heat exchange tubes can be arranged in the heating and settling section at the upper part of the tower body.

[0012] Further, in the above technical solution, the extraction section is provided with packing; an upper feed distributor is arranged above the packing for distributing the mixture of residue oil and solvent downward; a lower feed distributor can be arranged below the packing for distributing the solvent upward.

[0013] Further, in the above technical solution, the first implementation mode is adopted: the solvent can include a first solvent, a second solvent and a third solvent; the first solvent and the raw material residue oil are mixed by a mixer and then introduced into the upper feed distributor; the second solvent is heated by a heater and used as the heat exchange medium in the heat exchange tubes, and the second solvent after heat exchange is further cooled and introduced into the mixer; the third solvent is introduced into the lower feed distributor.

[0014] Further, in the above technical solution, the volume flow rate of the first solvent can be 0.15 times that of the raw material residue oil; the volume flow rate of the second solvent can be 0.45 times that of the raw material residue oil; the volume flow rate of the third solvent can be 4 times that of the raw material residue oil.

[0015] Further, in the above technical solution, the temperature of the second solvent after heating can be controlled at 90°C; the solvent temperature in the extraction section of the tower body can be controlled between 75 and 80°C.

[0016] Further, in the above technical solution, the second implementation method is adopted: the solvent may include a fourth solvent, a fifth solvent, and a sixth solvent; the fourth solvent and the raw material residue oil are mixed by a mixer and then fed into the upper feed distributor; the fifth solvent is heated by a heater and used as a heat exchange medium in the heat exchange tube, and the fifth solvent after heat exchange is mixed with the sixth solvent, further cooled, and fed into the lower feed distributor.

[0017] Further, in the above technical solution, the volume flow rate of the fourth solvent can be 0.6 times that of the raw material residue oil; the volume flow rate of the fifth solvent can be 0.45 times that of the raw material residue oil; the volume flow rate of the sixth solvent can be 3.55 times that of the raw material residue oil.

[0018] Further, in the above technical solution, the temperature of the fifth solvent after heating can be controlled at 90°C; the solvent temperature in the extraction section of the tower body can be controlled between 75 and 80°C.

[0019] Further, in the above technical solution, the third implementation method is adopted: the solvent may include a seventh solvent, an eighth solvent, and a ninth solvent; the seventh solvent and the raw material residue oil are mixed by a mixer and then fed into the upper feed distributor; the eighth solvent is heated by a heater and used as a heat exchange medium in the heat exchange tube, and the eighth solvent after heat exchange is fed into the heat tracing coil on the outer wall of the tower body as a heat tracing medium; the ninth solvent is cooled and then fed into the heat tracing coil and mixed with the eighth solvent and further fed into the lower feed distributor.

[0020] Further, in the above technical solution, the volume flow rate of the seventh solvent can be 0.6 times that of the raw material residue oil; the volume flow rate of the eighth solvent can be 0.45 times that of the raw material residue oil; the volume flow rate of the ninth solvent can be 3.55 times that of the raw material residue oil.

[0021] Further, in the above technical solution, the temperature of the eighth solvent after heating can be controlled at 90°C; the solvent temperature in the extraction section of the tower body can be controlled between 75 and 80°C.

[0022] Further, in the above technical solution, the fourth implementation method is adopted: the extraction section is provided with packing; an upper feed distributor is provided above the packing for distributing the mixture of residue oil and solvent downward; the heat exchange tube vertically penetrates through the heating and settling section and the extraction section, and solvent inlets for the extraction section of the tower body are provided at different heights at the lower part of the heat exchange tube for spraying the heat-exchanged solvent obliquely upward from the heat exchange tube into the packing to form upward distribution of the solvent.

[0023] Further, in the above technical solution, the solvent may include a tenth solvent and an eleventh solvent; the tenth solvent and the raw material residue oil are mixed by a mixer and then fed into the upper feed distributor; the eleventh solvent is heated by a heater and used as a heat exchange medium in the heat exchange tubes, and the heated eleventh solvent is sprayed into the tower body at the lower part of the heat exchange tubes for use as a deasphalting solvent.

[0024] Further, in the above technical solution, the volume flow rate of the tenth solvent may be 0.6 times that of the raw material residue oil; the volume flow rate of the eleventh solvent may be 3.7 times that of the raw material residue oil.

[0025] Further, in the above technical solution, the temperature of the eleventh solvent after heating may be controlled at 85 °C; the solvent temperature in the extraction section in the tower body may be controlled between 75 and 80 °C.

[0026] Further, in the above technical solution, the solvent feed inlet may adopt the structural form of a spray head or a nozzle.

[0027] Further, in the above technical solution, the first to the eleventh solvents may all adopt butane.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) By using a solvent (such as butane, etc.) to replace the existing heat exchange media such as steam and heat transfer oil, and cooperating with the heating form of the heat exchange tubes, the present invention ensures that even if the heat exchange tubes rupture and the heat exchange medium mixes with the raw materials in the extraction tower, it will not cause the problem of the existing heat exchange medium being entrained in the extraction tower discharge. Thus, not only can the product quality be prevented from being reduced, but also the solvent can be fully utilized to achieve the effect of energy conservation.

[0030] 2) In the first and second embodiments of the present invention, by further cooling the second solvent after heat exchange and mixing it with the first solvent to mix with the raw material residue oil, or mixing the fifth solvent after heat exchange with the sixth solvent outside the tower, further cooling and then feeding it into the lower feed distributor, both the heat exchange function is achieved, and the solvent used as the heat exchange medium is fully utilized. Since the temperature of the solvent used as the heat exchange medium has decreased during the heat exchange process, the energy consumption of the cooler is not high. Controlling the temperature of the mixed material entering the tower at 75 - 80 °C can meet the process requirements of solvent deasphalting.

[0031] 3) In the third embodiment of the present invention, the eighth solvent after heat exchange is further fed into the heat tracing coil on the outer wall of the tower. After being used as the heat exchange medium in the tower, it can also be used as a heat tracing medium on the outer wall of the tower. Further mixing with the ninth solvent outside the tower and cooling, and then feeding it into the lower feed distributor, both the heat exchange function inside the tower and the heat tracing function outside the tower are achieved, and the eighth solvent used as the heat exchange medium is fully utilized. Controlling the temperature of the mixed material entering the tower at 75 - 80 °C can still meet the process requirements of solvent deasphalting.

[0032] 4) In the fourth embodiment of the present invention, by lengthening the traditional heat exchange tubes to penetrate through the packing layer and arranging solvent nozzles at different heights at the lower part of the heat exchange tubes, the eleventh solvent after heat exchange can be directly used as the solvent in the tower. This can not only optimize the distribution of the solvent in the extraction tower, effectively avoid the downward movement of some upwardly distributed solvents under the action of gravity or the drag force of the descending asphaltene, but also, since some nozzles are arranged in the packing and the packing near the lower end is prone to blockage or poor flow due to the high asphaltene content here, the impact generated by the injection of the solvent can improve the flow environment of the packing here and enhance the separation efficiency of the packing.

[0033] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and be able to implement it according to the content of the specification, and at the same time to make the above and other objects, technical features and advantages of the present invention more understandable, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings as follows. Brief Description of the Drawings

[0034] Figure 1 is a schematic structural diagram of Embodiment 1 of the solvent deasphalting extraction tower of the present invention.

[0035] Figure 2 is a schematic structural diagram of Embodiment 2 of the solvent deasphalting extraction tower of the present invention.

[0036] Figure 3 is a schematic structural diagram of Embodiment 3 of the solvent deasphalting extraction tower of the present invention.

[0037] Figure 4 is a schematic structural diagram of Embodiment 4 of the solvent deasphalting extraction tower of the present invention.

[0038] Figure 5 is Figure 4 the overall top view schematic diagram of the heat exchange tubes in

[0039] Figure 6 is Figure 4 the partial enlarged view of A in

[0040] Main Reference Numeral Description:

[0041] 1 - Extraction tower body, 11 - Heat exchange tubes, 111 - Solvent feed port, 12 - Upper feed distributor, 13 - Packing, 14 - Lower feed distributor, 15 - Heating coil, 2 - Mixer, 3 - Heater, 4 - Cooler. Detailed Embodiments

[0042] The following combines the accompanying drawings to describe the detailed embodiments of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the detailed embodiments.

[0043] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or variations thereof such as "comprises" or "comprising" and the like shall be understood to include the stated element or component without excluding other elements or other components.

[0044] In this document, for convenience of description, spatial relative terms such as "below", "beneath", "lower", "above", "upper", etc. may be used to describe the relationship between one element or feature and another element or feature in the drawings. It should be understood that the spatial relative terms are intended to encompass different orientations of the object in use or operation in addition to the orientation depicted in the figures. For example, if the object in the figure is flipped, the element described as "below" or "beneath" another element or feature will be oriented "above" the said element or feature. Thus, the exemplary term "below" can encompass both the lower and upper directions. The object may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used herein should be interpreted accordingly.

[0045] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts and are not used to define a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. may also be interchanged with each other.

[0046] The extraction column of the present invention is used for solvent deasphalting. The extraction column is provided with packing and a heat exchanger. Under the pressure and temperature required by the process, the solvent and the residue oil are introduced into the extraction column to achieve the extraction and preparation of asphalt. The temperature at the top of the extraction column is higher than that in the middle and lower parts of the extraction column. Under the action of this temperature difference, the temperature of the deasphalted oil solution with a lower temperature gradually rises when flowing towards the top of the column, and the solubility of the solvent in the oil gradually decreases, resulting in the precipitation of asphaltenes and resins with relatively larger molecular weights. The density of asphaltenes and resins is relatively large, and they flow downward under the action of gravity, thereby reducing the content of asphaltenes and resins in the deasphalted oil. The deoiled asphalt then flows out from the bottom of the column. In the face of the problem that the heat exchange medium (steam, heat transfer oil, etc.) mixes with the raw materials due to the rupture of the heat exchange tubes at the top of the column, reducing the product quality, the present invention adopts a substance with the same properties as the solvent (such as butane, etc.) to replace the heat exchange medium, which can not only avoid reducing the product quality, but also make full use of the solvent to achieve the effect of energy saving; moreover, in addition to being arranged at the top of the column, the heat exchange tubes can also penetrate through the sedimentation separation section and the extraction section, and make full use of the heat-exchanged solvent without using the lower feed distributor, which can not only meet the process requirements of solvent deasphalting, but also effectively improve the problem of uneven solvent distribution.

[0047] The solvent deasphalting extraction column provided by the present invention comprises at least a column body 1 and heat exchange tubes 11. Among them, a heating and sedimentation section, an extraction section and a deoiled asphalt collection area are successively arranged in the column body 1 from top to bottom. Asphaltenes and resins are precipitated and settle downward in the heating and sedimentation section of the deasphalted oil solution after extraction; the heat exchange medium used in the heat exchange tubes 11 has the same properties as the solvent used for deasphalting in the column body, and the temperature of the solvent used as the heat exchange medium is higher than the temperature of the solvent used for deasphalting in the column body. By using a solvent (such as butane, etc.) to replace the existing heat exchange media such as steam and heat transfer oil, and in combination with the heating form of the heat exchange tubes, even if the heat exchange medium is mixed with the raw materials in the extraction column after the heat exchange tubes are ruptured, the problem of entraining the existing heat exchange medium in the extraction column discharge will not occur.

[0048] The following will be described in detail with four embodiments respectively.

[0049] Example 1

[0050] As Figure 1 shown, the diameter of the extraction column body 1 in this embodiment is 250 mm, and the height (tangent) is 2200 mm. A packing 13 is arranged in the extraction section in the middle of the column body 1, and heat exchange tubes 11 are arranged in the heating and sedimentation section in the upper part. The height of the heating and sedimentation section is 0.5 m, of which the heat exchange tubes account for 0.3 m; the height of the extraction section is 1.4 m, of which the packing height is 1.3 m; the height of the deoiled asphalt collection area is 0.3 m. An upper feed distributor 12 is arranged above the packing 13 for distributing the mixture of residue oil and solvent downward; a lower feed distributor 14 is arranged below the packing 13 for distributing the solvent upward.

[0051] Furthermore, as Figure 1As shown in the figure, the solvents in this embodiment include a first solvent, a second solvent, and a third solvent (all using butane, with the same solvent properties but different volume flow rates and temperatures). Among them, the first solvent and the raw material residue oil are mixed in mixer 2 and then fed into the upper feed distributor 12; the second solvent is heated by heater 3 and then used as the heat exchange medium in heat exchange tube 11, and the second solvent after heat exchange is further cooled by cooler 4 and then fed into mixer 2; the third solvent is directly fed into the lower feed distributor 14. Specifically, 3 kg / h of raw material residue oil and the first solvent are mixed in mixer 2 and then sent to the extraction column. The second solvent heated by heater 3 is fed into heat exchange tube 11 from the upper part of the extraction column. The second solvent, as the heat exchange medium, exchanges heat with the raw materials in the column and cools down, and then is also fed into mixer 2. By controlling cooler 4, the mixing temperature of the residue oil and the solvents (including the first solvent and the second solvent after heat exchange) at the rear end of mixer 2 is ensured to be 75 °C. Preferably but not restrictively, the volume flow rate of the first solvent is 0.15 times that of the raw material residue oil; the volume flow rate of the second solvent is 0.45 times that of the raw material residue oil; the volume flow rate of the third solvent is 4 times that of the raw material residue oil. The inventors found through experimental research that through such a volume flow rate ratio, the solvents can be fully utilized on the premise of meeting the process requirements.

[0052] Further as Figure 1 As shown in the figure, the deasphalted oil extracted by the solvents in the column flows out from the top of the extraction column, and the remaining deoiled asphalt flows out from the bottom of the extraction column. The pressure inside the extraction column is 3.8 MPa. Except for the upper heating and sedimentation section inside the extraction column, the rest is controlled at 75 - 80 °C. The temperature of the second solvent after being heated by heater 3 is controlled at 90 °C, that is, the temperature of the upper part of the extraction column is higher than that of the middle and lower parts of the extraction column. Under the action of this temperature difference, the temperature of the lower-temperature deasphalted oil solution gradually rises when flowing towards the top of the column, and the solubility of the solvent in the oil gradually decreases, resulting in the precipitation of asphaltenes and resins with relatively large molecular weights. The density of asphaltenes and resins is relatively large, and they flow downward under the action of gravity, thereby reducing the content of asphaltenes and resins in the deasphalted oil. The flow rate of the deasphalted oil at the top outlet of the column is 1.92 kg / h.

[0053] In this embodiment, the second solvent after heat exchange is further cooled and then mixed with the first solvent and the raw material residue oil, which not only realizes the heat exchange function but also makes full use of the second solvent used as the heat exchange medium. Since the temperature of the second solvent has decreased during the heat exchange process, the energy consumption of the cooler is not high. Controlling the temperature of the mixed material entering the column at 75 - 80 °C can meet the process requirements of solvent deasphalting.

[0054] Example 2

[0055] As Figure 2As shown, similar to Embodiment 1, the diameter of the extraction tower body 1 in this embodiment is 250 mm, and the height (tangent) is 2200 mm. A packing 13 is provided in the extraction section in the middle of the tower body 1, and heat exchange tubes 11 are provided in the upper heating and settling section. The height of the heating and settling section is 0.5 m, of which the heat exchange tubes account for 0.3 m; the height of the extraction section is 1.4 m, of which the height of the packing is 1.3 m; the height of the deoiled asphalt collection area is 0.3 m. An upper feed distributor 12 is provided above the packing 13 for distributing the mixture of residue oil and solvent downward; a lower feed distributor 14 is provided below the packing 13 for distributing the solvent upward.

[0056] Further as Figure 1 shown, the difference between this embodiment and Embodiment 1 is that the solvent includes a fourth solvent, a fifth solvent, and a sixth solvent; the fourth solvent and the raw material residue oil are mixed by a mixer 2 and then fed into the upper feed distributor 12; the fifth solvent is heated by a heater 3 and used as the heat exchange medium in the heat exchange tubes. After heat exchange, the fifth solvent is mixed with the sixth solvent, further cooled by a cooler 4 and fed into the lower feed distributor 14. Specifically, 3 kg / h of raw material residue oil and the fourth solvent are mixed by the mixer 2 and then fed into the extraction tower. The fifth solvent heated by the heater 3 is fed into the heat exchange tubes 11 from the upper part of the extraction tower. The fifth solvent is used as the heat exchange medium to exchange heat with the raw materials in the tower and cool down. After that, it is mixed with the sixth solvent outside the tower and cooled. By controlling the cooler 4, the mixing temperature of the solvent (including the sixth solvent and the heat-exchanged fifth solvent) fed into the lower feed distributor 14 is ensured to be 75 °C. Preferably but not restrictively, the volume flow rate of the fourth solvent is 0.6 times that of the raw material residue oil; the volume flow rate of the fifth solvent is 0.45 times that of the raw material residue oil; the volume flow rate of the sixth solvent is 3.55 times that of the raw material residue oil. The inventors have found through experimental research that in this embodiment, through such a volume flow rate ratio, the solvent can be fully utilized while ensuring the process requirements.

[0057] Further as Figure 2 shown, the deasphalted oil extracted by the solvent in the tower flows out from the top of the extraction tower, and the remaining deoiled asphalt flows out from the bottom of the extraction tower. The pressure inside the extraction tower is 3.8 MPa. Except for the upper heating and settling section inside the extraction tower, the rest is controlled at 75 - 80 °C. The temperature of the fifth solvent after being heated by the heater 3 is controlled at 90 °C, that is, the temperature of the upper part of the extraction tower is higher than that of the middle and lower parts of the extraction tower. Under the action of this temperature difference, the temperature of the lower-temperature deasphalted oil solution gradually rises when flowing towards the top of the tower, and the solubility of the solvent in the oil gradually decreases, resulting in the precipitation of asphaltenes and resins with relatively large molecular weights. The density of asphaltenes and resins is relatively large, and they flow downward under the action of gravity, thereby reducing the content of asphaltenes and resins in the deasphalted oil. The flow rate of the deasphalted oil at the top outlet of the tower is 1.90 kg / h.

[0058] In this embodiment, the fifth solvent after heat exchange is mixed with the sixth solvent outside the tower, further cooled, and then introduced into the lower feed distributor, which not only realizes the heat exchange function but also makes full use of the fifth solvent used as the heat exchange medium. Since the temperature of the fifth solvent has decreased during the heat exchange process, the energy consumption of the cooler is not high. Controlling the temperature of the mixed material entering the tower within 75-80°C can meet the process requirements of solvent deasphalting.

[0059] Example 3

[0060] As Figure 3 shown, the same as in Embodiments 1 and 2, the diameter of the extraction tower body 1 in this embodiment is 250 mm, and the height (tangent) is 2200 mm. A packing 13 is provided in the extraction section in the middle of the tower body 1, and heat exchange tubes 11 are provided in the upper heating and settling section. The height of the heating and settling section is 0.5 m, of which the heat exchange tubes account for 0.3 m; the height of the extraction section is 1.4 m, of which the packing height is 1.3 m; the height of the deoiled asphalt collection area is 0.3 m. An upper feed distributor 12 is provided above the packing 13 for distributing the mixture of residue oil and solvent downward; a lower feed distributor 14 is provided below the packing 13 for distributing the solvent upward.

[0061] Furthermore, as Figure 3As shown, the difference between this embodiment and Embodiments 1 and 2 is that the solvent includes a seventh solvent, an eighth solvent, and a ninth solvent; the seventh solvent and the raw material residue oil are mixed in Mixer 2 and then fed into the upper feed distributor 12; the eighth solvent is heated by Heater 3 and then used as the heat exchange medium in the heat exchange tube 11, and the eighth solvent after heat exchange is fed into the heating coil 15 on the outer wall of the tower body 1 as the heat tracing medium. The height of the heating coil used in this embodiment is 1.5 m, the heating coil selects a pipe with a diameter of φ15, and the center distance between adjacent heating coils is 25 mm; the ninth solvent is cooled by Cooler 4 and then also fed into the heating coil and mixed with the eighth solvent and further fed into the lower feed distributor 14. Specifically, 3 kg / h of the raw material residue oil and the seventh solvent are mixed in Mixer 2 and then fed into the extraction tower. The eighth solvent heated by Heater 3 is fed into the heat exchange tube 11 from the upper part of the extraction tower. The eighth solvent is used as the heat exchange medium to exchange heat with the raw materials in the tower and cool down, and then is fed into the heating coil 15 on the outer wall of the tower body as the heat tracing medium for the tower wall. At the same time, the ninth solvent cooled by Cooler 4 is also fed into the heating coil 15. The end of the heating coil 15 is connected to the lower feed distributor 14, and the mixing temperature of the solvent (including the ninth solvent from the heating coil 15 and the eighth solvent after heat exchange) fed into the lower feed distributor 14 is controlled at 75 °C by controlling Cooler 4. Preferably but not limitedly, the volume flow rate of the seventh solvent is 0.6 times that of the raw material residue oil; the volume flow rate of the eighth solvent is 0.45 times that of the raw material residue oil; the volume flow rate of the ninth solvent is 3.55 times that of the raw material residue oil. The inventors found through experimental research that in this embodiment, through such a volume flow rate ratio, the solvent can be fully utilized on the premise of ensuring the process requirements.

[0062] Further as Figure 3 shown, the deasphalted oil extracted by the solvent in the tower flows out from the top of the extraction tower, and the remaining deoiled asphalt flows out from the bottom of the extraction tower. The pressure inside the extraction tower is 3.8 MPa. Except for the upper heating and settling section inside the extraction tower, the remaining parts are controlled at 75 - 80 °C. The temperature of the eighth solvent after being heated by Heater 3 is controlled at 90 °C, that is, the temperature of the upper part of the extraction tower is higher than that of the middle and lower parts of the extraction tower. Under the action of this temperature difference, the temperature of the lower-temperature deasphalted oil solution gradually rises when flowing towards the top of the tower, and the solubility of the solvent in the oil gradually decreases, resulting in the precipitation of asphaltenes and resins with relatively large molecular weights. The density of asphaltenes and resins is relatively large, and they flow downward under the action of gravity, thereby reducing the content of asphaltenes and resins in the deasphalted oil. The flow rate of the deasphalted oil at the top outlet of the tower is 1.93 kg / h.

[0063] In this embodiment, the eighth solvent after heat exchange is further passed into the heating coil on the outer wall of the tower. After serving as the heat exchange medium inside the tower, it can also be used as the heating medium on the outer wall of the tower. It is further mixed with the ninth solvent outside the tower and then cooled and passed into the lower feed distributor. This not only realizes the functions of heat exchange inside the tower and heating outside the tower, but also makes full use of the eighth solvent used as the heat exchange medium. Since the temperature of the eighth solvent has decreased during the heat exchange process, the energy consumption of the cooler is not high. Controlling the temperature of the mixed material entering the tower at 75-80 °C can meet the process requirements of solvent deasphalting.

[0064] Example 4

[0065] As Figure 4 shown, the same as in Embodiments 1 to 3, the diameter of the extraction tower body 1 in this embodiment is 250 mm, and the height (tangent) is 2200 mm. A packing 13 is provided in the extraction section in the middle of the tower body 1. The height of the heating and settling section is 0.5 m; the height of the extraction section is 1.4 m, of which the packing height is 1.3 m; the height of the deoiled asphalt collection area is 0.3 m. An upper feed distributor 12 is provided above the packing 13 for distributing the mixture of residue oil and solvent downward. Different from Embodiments 1 to 3, the heat exchange tube 11 in this embodiment penetrates through the heating and settling section and the extraction section, that is, the heat exchange tube 11 penetrates through the packing layer; in addition, no lower feed distributor is provided in this embodiment. As Figure 5 、 6 shown, in this embodiment, solvent inlet ports 111 for the extraction section of the tower body are provided at different heights at the lower part of the heat exchange tube 11, and the heat-exchanged solvent can be sprayed obliquely upward from the heat exchange tube 11 into the packing 13 to form upward distribution of the solvent. The solvent inlet ports 111 can adopt the structural forms of nozzles or spray nozzles.

[0066] Further, the solvent in this embodiment includes a tenth solvent and an eleventh solvent; the tenth solvent and the raw material residue oil are mixed by a mixer 2 and then passed into the upper feed distributor 12; the eleventh solvent is heated by a heater and used as the heat exchange medium in the heat exchange tube 11, and the heat-exchanged eleventh solvent is sprayed into the tower body at the lower part of the heat exchange tube 11 for use as the deasphalting solvent. Since the heat exchange tube in this embodiment is relatively long, the eleventh solvent after heat exchange at the bottom can basically be controlled at the required temperature (that is, between 75-80 °C), but the temperature of the eleventh solvent at the rear end of the heater 3 needs to be appropriately reduced. In this embodiment, the heated temperature is set at 85 °C. Preferably but not restrictively, the volume flow rate of the tenth solvent is 0.6 times that of the raw material residue oil; the volume flow rate of the eleventh solvent is 3.7 times that of the raw material residue oil. The inventor found through experimental research that through such a volume flow rate ratio in this embodiment, the solvent can be fully utilized while ensuring the process requirements.

[0067] Further as Figure 4As shown, the deasphalted oil extracted by the solvent in the tower flows out from the top of the extraction tower, and the remaining deoiled asphalt flows out from the bottom of the extraction tower. The pressure inside the extraction tower is 3.8 MPa. Except for the upper heating and settling section inside the extraction tower, the remaining parts are controlled at 75 - 80 °C. The temperature of the eleventh solvent is controlled at 85 °C after being heated by the heater 3, that is, the temperature of the upper part of the extraction tower is higher than that of the middle and lower parts of the extraction tower. Under the action of this temperature difference, the temperature of the deasphalted oil solution with a lower temperature gradually rises when flowing towards the top of the tower, and the solubility of the solvent in the oil gradually decreases, resulting in the precipitation of asphaltenes and resins with relatively large molecular weights. The densities of asphaltenes and resins are relatively large, and they flow downward under the action of gravity, thereby reducing the contents of asphaltenes and resins in the deasphalted oil. The flow rate of the deasphalted oil at the top outlet of the tower is 1.92 kg / h.

[0068] In this embodiment, the traditional heat exchange tubes are lengthened and penetrate through the packing layer, and solvent nozzles are arranged at different heights at the lower part of the heat exchange tubes, so that the eleventh solvent after heat exchange can be directly used as the solvent in the tower. In the traditional feed distribution method (i.e., using a lower feed distributor), the solvent is concentrated in a certain part of the extraction tower. This method is prone to cause local solvent overdose, which is not conducive to the full utilization of the solvent in the entire extraction tower. Some of the upwardly distributed solvent will move downward under the action of gravity or the drag force of the descending asphaltenes. However, in this embodiment, by arranging solvent nozzles in sections at different heights, the distribution of the solvent in the extraction tower can be optimized. At the same time, some nozzles are arranged in the packing. Since the packing near the lower end has a relatively high content of asphaltenes, it is prone to blockage or poor flow. The impact generated by the injection of the solvent can improve the flow environment of the packing here and enhance the separation efficiency of the packing.

[0069] The foregoing description of specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and obviously, many changes and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize various different exemplary embodiments of the invention, as well as various different selections and changes. Any simple modifications, equivalent variations, and modifications made to the above exemplary embodiments shall fall within the protection scope of the present invention.

Claims

1. A solvent deasphalting extraction tower, characterized in that, it includes: a tower body, which is successively provided with a heating and settling section, an extraction section, and a deoiled asphalt collection area from top to bottom; the deasphalted oil solution after extraction precipitates asphaltenes and resins in the heating and settling section and settles downward; heat exchange tubes, the heat exchange medium used therein is the same as the solvent used for deasphalting in the tower body, and the temperature of the solvent used as the heat exchange medium is higher than the temperature of the solvent used for deasphalting in the tower body.

2. The solvent deasphalting extraction tower according to claim 1, characterized in that, the heat exchange tubes are arranged in the heating and settling section at the upper part of the tower body.

3. The solvent deasphalting extraction tower according to claim 2, characterized in that, the extraction section is provided with packing; an upper feed distributor is arranged above the packing for distributing the mixture of residual oil and solvent downward; a lower feed distributor is arranged below the packing for distributing the solvent upward.

4. The solvent deasphalting extraction tower according to claim 3, characterized in that, the solvent includes a first solvent, a second solvent, and a third solvent; the first solvent and the raw material residual oil are mixed by a mixer and then introduced into the upper feed distributor; the second solvent is heated by a heater and used as the heat exchange medium in the heat exchange tubes, and the second solvent after heat exchange is further cooled and introduced into the mixer; the third solvent is introduced into the lower feed distributor.

5. The solvent deasphalting extraction tower according to claim 4, characterized in that, the volume flow rate of the first solvent is 0.15 times that of the raw material residual oil; the volume flow rate of the second solvent is 0.45 times that of the raw material residual oil; the volume flow rate of the third solvent is 4 times that of the raw material residual oil.

6. The solvent deasphalting extraction tower according to claim 4, characterized in that, the temperature of the second solvent after heating is 90 °C; the solvent temperature in the extraction section in the tower body is controlled between 75 and 80 °C.

7. The solvent deasphalting extraction tower according to claim 3, characterized in that, the solvent includes a fourth solvent, a fifth solvent, and a sixth solvent; the fourth solvent and the raw material residual oil are mixed by a mixer and then introduced into the upper feed distributor; the fifth solvent is heated by a heater and used as the heat exchange medium in the heat exchange tubes, and the fifth solvent after heat exchange is mixed with the sixth solvent, further cooled and introduced into the lower feed distributor.

8. The solvent deasphalting extraction tower according to claim 7, characterized in that, the volume flow rate of the fourth solvent is 0.6 times that of the raw material residual oil; the volume flow rate of the fifth solvent is 0.45 times that of the raw material residual oil; the volume flow rate of the sixth solvent is 3.55 times that of the raw material residual oil.

9. The solvent deasphalting extraction tower according to claim 7, characterized in that, the temperature of the fifth solvent after heating is 90 °C; the solvent temperature in the extraction section in the tower body is controlled between 75 and 80 °C.

10. The solvent deasphalting extraction tower according to claim 3, characterized in that, The solvent includes a seventh solvent, an eighth solvent, and a ninth solvent; the seventh solvent is mixed with the raw material residue oil in a mixer and then introduced into the upper feed distributor; the eighth solvent is heated by a heater and used as a heat exchange medium in the heat exchange tubes, and the eighth solvent after heat exchange is introduced into the heating coil on the outer wall of the tower body as a heating medium; the ninth solvent is cooled and then introduced into the heating coil, mixed with the eighth solvent, and further introduced into the lower feed distributor.

11. The solvent deasphalting extraction tower according to claim 10, characterized in that, the volume flow rate of the seventh solvent is 0.6 times that of the raw material residue oil; the volume flow rate of the eighth solvent is 0.45 times that of the raw material residue oil; the volume flow rate of the ninth solvent is 3.55 times that of the raw material residue oil.

12. The solvent deasphalting extraction tower according to claim 10, characterized in that, the temperature of the eighth solvent after heating is 90 °C; the solvent temperature in the extraction section inside the tower body is controlled between 75 and 80 °C.

13. The solvent deasphalting extraction tower according to claim 1, characterized in that, the extraction section is provided with packing; an upper feed distributor is arranged above the packing for distributing the mixture of residue oil and solvent downward; the heat exchange tubes vertically penetrate through the heating and settling section and the extraction section, and solvent inlets for the extraction section of the tower body are arranged at different heights at the lower part of the heat exchange tubes for spraying the heat-exchanged solvent obliquely upward from inside the heat exchange tubes into the packing to form upward distribution of the solvent.

14. The solvent deasphalting extraction tower according to claim 13, characterized in that, the solvent includes a tenth solvent and an eleventh solvent; the tenth solvent is mixed with the raw material residue oil in a mixer and then introduced into the upper feed distributor; the eleventh solvent is heated by a heater and used as a heat exchange medium in the heat exchange tubes, and the eleventh solvent after heat exchange is sprayed into the tower body at the lower part of the heat exchange tubes and used as a deasphalting solvent.

15. The solvent deasphalting extraction tower according to claim 14, characterized in that, the volume flow rate of the tenth solvent is 0.6 times that of the raw material residue oil; the volume flow rate of the eleventh solvent is 3.7 times that of the raw material residue oil.

16. The solvent deasphalting extraction tower according to claim 14, characterized in that, the temperature of the eleventh solvent after heating is 85 °C; the solvent temperature in the extraction section inside the tower body is controlled between 75 and 80 °C.

17. The solvent deasphalting extraction tower according to claim 13, characterized in that, the solvent inlets adopt the structural form of spray heads or nozzles.

18. The solvent deasphalting extraction tower according to claim 4, 7, 10 or 14, characterized in that, the first to eleventh solvents all adopt butane.

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