Solvent deasphalting extraction tower

Abstract

The invention discloses a solvent deasphalting extraction tower, which 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; an inner cylinder is arranged in the tower body, an annular space is formed between the inner cylinder and the tower wall, and asphaltene and colloid are separated out from the extracted deasphalted oil solution in the heating settling section and are downwards settled in the annular space; the heat exchange pipe is spiral and is arranged in the annular space, a heat exchange medium used in the heat exchange pipe has the same property as 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. 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, and the problem that the discharged material of the extraction tower carries steam or heat-conducting oil and other existing heat exchange media can be effectively avoided; the heat exchange pipe is arranged in the annular space between the inner cylinder and the tower wall, so that colloid and asphaltene separated out after heat exchange can move downwards from an independent channel, and the solvent-oil ratio per unit volume in the extraction section filler is effectively increased.

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 removes resins and asphaltenes from the vacuum residue (or atmospheric residue) obtained from crude oil distillation by extraction, 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 oils cannot be vaporized due to their high boiling points and remain in the vacuum residue. They are separated by taking advantage of the difference in their solubility in solvents between resins and asphaltenes. Commonly used solvents are propane, butane, pentane, hexane, or a mixture of propane and butane.

[0003] For example, Chinese Patent Application CN112680242A discloses an internal member at the top of an extraction tower, an extraction tower, and a solvent deasphalting extraction method. The internal 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 evenly 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 connected in sequence. 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 asphaltene entrainment.

[0004] However, in similar existing solvent deasphalting technologies, in order to reduce the amount of deoiled asphalt entrained in the overhead product of the extraction tower, a heater is generally provided at the top of the extraction tower to reduce the content of resins 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 transfer oil, etc.) cooperating with heat exchange tubes. With this heating method, when the heat exchange tubes rupture, the heat exchange medium will mix with the raw materials in the extraction tower, resulting in the problem of heat exchange medium entrainment in the extraction tower product, 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 not only meet the heat exchange requirements and will not cause the problem of heat exchange medium entrainment in the extraction tower product when the heat exchange tubes rupture; at the same time, the resins and asphaltenes precipitated after heat exchange can descend through a separate channel, which can effectively increase the solvent-to-oil ratio per unit volume in the extraction section packing.

[0006] The information disclosed in this background art section is only intended to enhance the overall understanding 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 entrainment of steam or heat transfer oil in the column discharge. By arranging the heat exchange tubes in the annular space between the inner cylinder and the column wall, the precipitated gum and asphaltene after heat exchange can descend through a separate channel, effectively increasing the solvent-oil ratio per unit volume in the packing of the extraction section.

[0008] Another object of the present invention is to provide a solvent deasphalting extraction column. By extending the heat exchange tubes to the bottom of the column and selectively introducing cold solvent at different heights in the middle of the heat exchange tubes, the height of the heat exchange section of the heat exchange tubes can be adjusted when the contents of asphaltene and gum in the raw material change, thereby improving the extraction efficiency in the column.

[0009] To achieve the above object, the present invention provides a solvent deasphalting extraction column, comprising: a column body, which is successively provided with a heating and settling section, an extraction section and a deoiled asphalt collection area from top to bottom; an inner cylinder is arranged in the column body to form an annular space between the inner cylinder and the column wall, and the deasphalted oil solution after extraction precipitates asphaltene and gum in the heating and settling section and descends in the annular space; heat exchange tubes, which are spiral and arranged in the annular space, and the heat exchange medium used in the heat exchange tubes 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.

[0010] 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 annular space; discharge ports are provided at the corresponding positions on the upper part of the inner cylinder wall and the heat exchange tubes.

[0011] Further, in the above technical solution, the extraction section is arranged in the inner cylinder in the middle and lower part of the column body, and 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; a lower feed distributor is provided below the packing for distributing the solvent upward.

[0012] Further, in the above technical solution, 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 and then introduced into the heat exchange tubes from the top as the heat exchange medium for circulating heat exchange; the third solvent is introduced into the lower feed distributor.

[0013] Further, in the above technical solution, the volume flow rate of the first solvent can be controlled to be 0.6 times that of the raw material residue oil; the volume flow rate of the third solvent can be controlled to be 4 times that of the raw material residue oil.

[0014] Further, in the above technical solution, the temperature of the second solvent after heating can be controlled to be 90 °C; the solvent temperature in the extraction section in the inner cylinder of the column body can be controlled between 75 and 80 °C.

[0015] Further, in the above technical solution, the heat exchange tubes can be pipes with a diameter of 10 mm, and the center-to-center distance between adjacent tubes at the overall longitudinal section of the heat exchange tubes can be 15 mm.

[0016] Further, in the above technical solution, the heat exchange tubes can also extend from the upper end to the lower end of the inner cylinder in the annular space, and the heat exchange tubes have: a heat exchange section, which is located at the corresponding position of the heating and sedimentation section in the upper part of the annular space of the tower body and is used for introducing hot solvent; a discharge port is provided at the corresponding position of the upper part of the inner cylinder wall and at the corresponding position of this heat exchange section; a solvent feeding section, which is the pipe section below the heat exchange section and is used for supplementing cold solvent into the heat-exchanged hot solvent and using the mixed solvent as the solvent in the extraction section in the inner cylinder.

[0017] Further, in the above technical solution, the cold solvent supplement pipeline can be composed of multiple branch pipes. The connection ports of the multiple branch pipes and the heat exchange tubes are arranged at different heights, and the multiple branch pipes can be independently controlled for feeding to adjust the height ratio of the heat exchange section to the solvent feeding section.

[0018] Further, in the above technical solution, the extraction section can be arranged in the inner cylinder in the middle and lower part of the tower body. The extraction section is provided with packing; an upper feed distributor is provided above the packing and is used for distributing the mixture of residue oil and solvent downward; a lower feed distributor is provided below the packing and is used for distributing the mixed solvent from the solvent feeding section upward.

[0019] Further, in the above technical solution, the solvent can include a fourth solvent, the aforementioned hot solvent, and the aforementioned cold solvent; the fourth solvent and the raw material residue oil are mixed by a mixer and then introduced into the upper feed distributor; the hot solvent is introduced into the heat exchange tubes from the top as a heat exchange medium, continues to flow spirally downward after heat exchange in the heat exchange section, enters the solvent feeding section, and is mixed with the cold solvent; the mixed solvent is then introduced into the lower feed distributor.

[0020] Further, in the above technical solution, the volume flow rate of the fourth solvent can be controlled to be 0.6 times that of the raw material residue oil; the volume flow rate of the hot solvent can be controlled to be 0.6 times that of the raw material residue oil; the volume flow rate of the cold solvent can be controlled to be 3.4 times that of the raw material residue oil.

[0021] Further, in the above technical solution, the temperature of the hot solvent can be controlled to be 90 °C, and the temperature of the cold solvent can be controlled to be 73 °C to ensure that the solvent temperature in the extraction section in the inner cylinder of the tower body is controlled between 75 and 80 °C.

[0022] Further, in the above technical solution, the first to fourth solvents, as well as the hot solvent and the cold solvent, can all adopt butane.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) In the present invention, 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 when the heat exchange tubes are ruptured and the heat exchange medium is mixed with the raw materials in the extraction column, the problem that the existing heat exchange medium is entrained in the discharged material of the extraction column will not occur. Thus, not only can the reduction of product quality be avoided, but also the solvent can be fully utilized to achieve the effect of energy conservation;

[0025] 2) In the first embodiment of the present invention, compared with the traditional solvent deasphalting extraction column (where the precipitated asphaltenes and resins move downward over the entire cross-section inside the column), the asphaltenes and resins precipitated in the heating and settling section where the heat exchange tubes are located move downward through the annular space outside the inner cylinder. This part of the precipitated asphaltenes and resins moves downward outside the inner cylinder without contacting the solvent. This method can effectively increase the solvent-oil ratio per unit volume in the packing of the extraction section, thereby improving the extraction efficiency; in addition, in the traditional extraction column, the deasphalted oil in the column will return to the middle and lower parts of the column under the drag force of the descending asphaltenes and resins, thereby reducing the extraction efficiency, and this problem can also be avoided in the present invention;

[0026] 3) In the second embodiment of the present invention, in addition to achieving the beneficial effects of the first embodiment, the solvent used as the heat exchange medium can be applied to the solvent in the extraction section inside the column body. Moreover, by arranging the heat exchange tubes to extend downward in the annular space and through the branch inlets arranged at different heights of the cold solvent supply pipeline, the height of the upper heating and settling section of the column body (i.e., the heat exchange section of the heat exchange tubes) can be changed according to actual needs. For example: when the content of asphaltenes and resins in the raw material residue oil increases, the content of asphaltenes and resins carried by the deasphalted oil at the top of the column will increase correspondingly. Without changing the structure of the extraction column, by adjusting the injection position of the cold solvent in the present invention, the height of the heat exchange section of the heat exchange tubes can be increased, thereby increasing the heat exchange area of the heating and settling section of the column body; the pipe section below the heat exchange section can provide a solvent at 75 - 80 °C for the extraction section in the inner cylinder by mixing the cold solvent with the heat-exchanged hot solvent to meet the process requirements of solvent deasphalting.

[0027] The above description is only an overview of the technical solution of the present invention. In order to be able to more clearly understand the technical means of the present invention and implement it according to the content of the specification, and in order to make the above and other purposes, technical features, and advantages of the present invention more understandable, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of Embodiment 1 of the solvent deasphalting extraction column of the present invention.

[0029] Figure 2 is Figure 1 a cross-sectional view of the heat exchange tube location (showing the material flow direction at the discharge port of the inner cylinder)

[0030] Figure 3 It is a schematic structural diagram of Embodiment 2 of the solvent deasphalting extraction tower of the present invention.

[0031] Figure 4 is Figure 3 a schematic diagram of the spiral structure of the heat exchange tubes in (showing the connection relationship between the heat exchange tubes and the lower feed distributor).

[0032] Main reference numerals description:

[0033] 1 - Extraction tower body, 10 - Inner cylinder, 101 - Closed end of the inner cylinder, 11 - Heat exchange tubes, 12 - Upper feed distributor, 13 - Packing, 14 - Lower feed distributor, 2 - Mixer, 3 - Cold solvent feed pipe, 31 - Valve. Detailed implementation manners

[0034] The following will describe in detail the specific implementation manners of the present invention with reference to the accompanying drawings. However, it should be understood that the protection scope of the present invention is not limited by the specific implementation manners.

[0035] Unless otherwise clearly stated, in the whole specification and claims, the term "comprise" or its variations such as "comprises" or "including" etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0036] In this article, for the convenience of description, spatial relative terms such as "below", "beneath", "under", "above", "over", "on" etc. can be used to describe the relationship between one element or feature and another element or feature in the accompanying drawings. It should be understood that the spatial relative terms are intended to cover different directions of the object in use or operation in addition to the directions depicted in the drawings. For example, if the object in the drawing is flipped, the element described as "below" or "under" another element or feature will be oriented "above" the said element or feature. Therefore, the exemplary term "below" can include both the below and above directions. The object can also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used herein should be interpreted accordingly.

[0037] In this article, terms such as "first", "second" etc. are used to distinguish two different elements or parts, rather than to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second" etc. can also be interchanged with each other.

[0038] 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 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 increases 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 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 deoiled asphalt flows out from the bottom of the column. In the face of the problem that the mixing of the heat exchange medium (such as steam, heat transfer oil, etc.) and the raw material due to the rupture of the heat exchange tubes at the top of the column reduces 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, thereby avoiding the reduction of product quality; in addition, the present invention can also effectively increase the solvent-oil ratio per unit volume in the packing of the extraction section and improve the extraction efficiency in the column.

[0039] As Figure 1 , 2 shown, the solvent deasphalting extraction column provided by the present invention at least includes a column body 1 and heat exchange tubes 11. Among them, a heating and settling section, an extraction section, and a deoiled asphalt collection area are sequentially arranged in the column body 1 from top to bottom; an inner cylinder 10 is arranged in the column body to form an annular space between the inner cylinder 10 and the column wall, and asphaltenes and resins are precipitated in the heating and settling section of the deasphalted oil solution after extraction and settle downward in the annular space. The heat exchange tubes 11 are spiral and arranged in the annular space. 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 cooperating with the heating form of the heat exchange tubes 11, even when the heat exchange tubes 11 rupture and the heat exchange medium is mixed with the raw materials in the extraction column, it will not cause the problem that the existing heat exchange medium is entrained in the extraction column discharge; in addition, compared with the traditional solvent deasphalting extraction column, the asphaltenes and resins precipitated at the top of the column (i.e., the upper part of the annular space) of the present invention can move downward from the outside of the inner cylinder, avoiding contact with the raw materials during the extraction process. Therefore, the solvent-oil ratio per unit volume in the packing of the extraction section (i.e., the ratio of the solvent amount to the raw material residue oil amount) can be effectively increased, thereby improving the extraction efficiency.

[0040] The following will be described in detail with two specific embodiments respectively.

[0041] Example 1

[0042] As Figure 1 , Figure 2As shown in the figure, the diameter of the extraction tower body 1 in this embodiment is 250 mm, and the height (tangent) is 2200 mm. A cylindrical inner cylinder 10 is provided inside the tower body 1. There is an annular space between the inner cylinder 10 and the wall surface of the tower body 1. A spiral heat exchange tube 11 is provided in the upper part of this annular space (that is, the heating and sedimentation section of the tower body). Discharge ports are provided at the corresponding positions on the upper part of the wall surface of the inner cylinder 10 and the heat exchange tubes. The height of the heat exchange tube 11 is 500 mm. The heat exchange tube can adopt a pipe with a diameter of 10 mm, and the center distance between adjacent tubes in the overall longitudinal section of the heat exchange tube 11 is 15 mm. The height of the inner cylinder 10 is 1800 mm. Packing 13 is provided in the extraction section in the middle and lower parts of the inner cylinder 10 of the tower body 1, and the height of the packing is 1200 mm. The deoiled asphalt collection area is arranged at the bottom of the tower body 1. An upper feed distributor 12 is provided above the packing 13 for distributing the mixture of residue oil (the properties of the raw residue oil are shown in Table 1) and the solvent downward; a lower feed distributor 14 is provided below the packing 13 for distributing the solvent upward.

[0043] Further as Figure 1 shown, the solvent in this embodiment includes a first solvent, a second solvent, and a third solvent (all can adopt butane); the first solvent and the raw residue oil are mixed by a mixer 2 and then fed into the upper feed distributor 12; the second solvent is heated and then fed into the heat exchange tube 11 from the top as a heat exchange medium, and can conduct circulating heat exchange, or the heat-exchanged second solvent can be cooled and used as a deasphalting solvent in the extraction section in the tower body 1; the third solvent is fed into the lower feed distributor 14. Preferably but not limitedly, the volume flow rate of the first solvent can be controlled to be 0.6 times that of the raw residue oil; the volume flow rate of the third solvent can be controlled to be 4 times that of the raw residue oil. The inventor found through experimental research that through such a volume flow rate ratio, the solvent can be fully utilized on the premise of ensuring the process requirements.

[0044] Further as Figure 1 shown, 3.6 kg / h of raw residue oil and the first solvent are mixed by a mixer and then fed into the extraction tower. The deasphalted oil extracted by the solvent flows out from the top of the extraction tower (as Figure 1 shown by the dotted arrow in the annular space), and the remaining deoiled asphalt flows out from the bottom of the extraction tower. The pressure inside the extraction tower is 3.8 - 4.0 MPa. Except for the heating and sedimentation section at the position where the heat exchange tubes are located (that is, the upper part of the annular space) inside the extraction tower, the rest is controlled at 75 - 80 °C, and the temperature of the heating and sedimentation section of the extraction tower is controlled at 90 °C by controlling the temperature and flow rate of the heat exchange medium (that is, the second solvent). That is, the temperature at the top of the tower is higher than that in the middle and lower parts of the 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 asphaltene and resin with relatively large molecular weights. The density of asphaltene and resin is relatively large, and it flows downward under the action of gravity (as Figure 1As shown by the solid arrows in the annular space, the content of asphaltenes and resins in the deasphalted oil is thus reduced. The precipitated asphaltenes and resins move downward along the annular space between the inner cylinder 10 and the tower wall to the bottom of the extraction tower. In this embodiment, the flow rate of the deasphalted oil at the top outlet of the tower is 1.98 kg / h. The product yields and properties are shown in Table 2.

[0045] In this embodiment, the second solvent (butane) is used as the heat exchange medium, which can not only meet the heat exchange requirements at the top of the extraction tower, but also effectively avoid the problems of the existing heat exchange media such as the entrainment of steam or heat transfer oil in the discharge of the extraction tower; in addition, compared with the traditional solvent deasphalting extraction tower (where the precipitated asphaltenes and resins move downward across the entire cross-section of the tower), in this embodiment, the asphaltenes and resins precipitated in the heating and settling section where the heat exchange tubes are located move downward along the annular space outside the inner cylinder. This part of the precipitated asphaltenes and resins move downward from the outside of the inner cylinder without contacting the solvent. This method can effectively increase the solvent-oil ratio per unit volume in the packing of the extraction section, thereby improving the extraction efficiency; in addition, in the traditional extraction tower, the deasphalted oil in the tower will return to the middle and lower part of the tower under the drag force of the descending asphaltenes and resins, thereby reducing the extraction efficiency, and this problem can also be avoided in this embodiment.

[0046] Example 2

[0047] As Figure 3 、 4 shown, the diameter of the tower body 1 of the extraction tower in this embodiment is 250 mm, and the height (tangential) is 2200 mm. A cylindrical inner cylinder 10 is provided inside the tower body 1. There is an annular space between the inner cylinder 10 and the wall of the tower body 1. A spiral heat exchange tube 11 is provided through the annular space from top to bottom (i.e., extending from the upper end of the inner cylinder 10 to the lower end). The heat exchange tube 11 has a heat exchange section and a solvent feeding section. Among them, the heat exchange section is located at the corresponding position of the heating and settling section in the upper part of the annular space of the tower body 1 for introducing hot solvent; an outlet is provided at the corresponding position on the upper part of the wall of the inner cylinder 10 and at this heat exchange section. The solvent feeding section is the pipe section below the heat exchange section for supplementing cold solvent to the heat-exchanged hot solvent and using the mixed solvent as the solvent in the extraction section in the inner cylinder. The height of the heat exchange tube 11 is 1700 mm. The heat exchange tube can use a pipe with a diameter of 10 mm, and the center distance between adjacent tubes in the overall longitudinal section of the heat exchange tube 11 is 15 mm. The height of the inner cylinder 10 is 1800 mm. Packing 13 is provided in the extraction section in the middle and lower part of the inner cylinder 10 of the tower body 1, and the height of the packing is 1200 mm. The deoiled asphalt collection area is arranged at the bottom of the tower body 1. An upper feed distributor 12 is provided above the packing 13 for distributing the mixture of residue oil (the properties of the raw residue oil are shown in Table 1) and solvent downward; a lower feed distributor 14 is provided below the packing 13 for distributing the solvent upward.

[0048] Furthermore, as Figure 3 、 4As shown, the supplementary pipeline 3 of the cold solvent is composed of multiple branch pipes. The connection ports of the multiple branch pipes to the heat exchange pipes 11 are set at different heights. The multiple branch pipes can be independently controlled for feeding through the valves 31 provided on their respective pipelines, so as to adjust the height ratio of the heat exchange section to the solvent feeding section. For example, when the valve 31 of the uppermost branch pipe is opened, the height of the heat exchange section is the smallest; when the valve 31 of the lowermost branch pipe is opened, the height of the heat exchange section is the largest.

[0049] Furthermore, as Figure 3 shown, the solvent in this embodiment includes a fourth solvent, the aforementioned hot solvent, and the aforementioned cold solvent; the fourth solvent and the raw material residue oil are mixed in a mixer 2 and then fed into the upper feed distributor 12; the hot solvent is fed into the heat exchange pipes 11 from the top as a heat exchange medium, and after heat exchange in the heat exchange section, it continues to flow spirally downward into the solvent feeding section and is mixed with the cold solvent; the mixed solvent is fed into the lower feed distributor 14. Preferably but not restrictively, the volume flow rate of the fourth solvent can be controlled to be 0.6 times that of the raw material residue oil; the volume flow rate of the hot solvent can be controlled to be 0.6 times that of the raw material residue oil; the volume flow rate of the cold solvent can be controlled to be 3.4 times that of the raw material residue oil. The inventors found through experimental research that through such a volume flow rate ratio, the solvent can be fully utilized on the premise of meeting the process requirements. Further, the temperature of the hot solvent is 90°C, and the temperature of the cold solvent is 73°C, so as to ensure that the solvent temperature in the extraction section in the inner cylinder of the tower is controlled between 75 and 80°C.

[0050] Furthermore, as Figure 3 shown, 3.6 kg / h of raw material residue oil and the fourth solvent are mixed in a mixer and then fed into the extraction tower. The hot solvent is fed into the heat exchange pipes at the top of the extraction tower, and the cold solvent is fed into the middle section of the heat exchange pipes. The deasphalted oil extracted by the solvent 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 - 4.0 MPa. Except for the heat exchange section of the heat exchange pipes inside the extraction tower (i.e., the heating and settling section of the tower body), the rest is controlled at 75 - 80°C. By controlling the temperature and flow rate of the heat exchange medium (i.e., the hot solvent), the temperature of the heating and settling section of the extraction tower is controlled at 90°C. Under the action of this temperature difference, the deasphalted oil solution with a lower temperature enters the annular space from the discharge port of the inner cylinder, and its temperature gradually rises when flowing towards the top of the tower in the annular space. 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 under the action of gravity, they flow downward in the annular space, thereby reducing the content of asphaltenes and resins in the deasphalted oil. The precipitated asphaltenes and resins move downward along the annular space between the inner cylinder 10 and the tower wall to the bottom of the extraction tower. In this embodiment, the flow rate of the deasphalted oil at the top outlet of the tower is 2.02 kg / h. The product yield and properties are shown in Table 2.

[0051] In addition to achieving the technical effects of Embodiment 1, in this embodiment, by arranging the heat exchange tubes to extend downward in the annular space and providing branch inlets at different heights of the cold solvent supply pipeline, the height of the upper heating and sedimentation section of the tower body (i.e., the heat exchange section of the heat exchange tubes) can be changed according to actual needs. For example, when the contents of asphaltene and resin in the raw material residue oil increase, the contents of asphaltene and resin carried by the deasphalted oil at the top of the tower will correspondingly increase. Without changing the structure of the extraction tower, it is very difficult to achieve the ideal extraction efficiency only by adjusting the solvent amount. At this time, the injection position of the cold solvent in this embodiment can be adjusted to increase the height of the heat exchange section of the heat exchange tubes, thereby increasing the heat exchange area of the heating and sedimentation section of the tower body. The pipe section below the heat exchange section can provide a solvent at 75 - 80 °C for the extraction section in the inner cylinder by mixing the cold solvent with the heat-exchanged hot solvent.

[0052] Comparative Example 1

[0053] For the extraction tower of a solvent deasphalting unit with the same size and the same processing scale commonly used currently, the flow rate of the deasphalted oil at the top of the tower is 1.88 kg / h. The product yields and properties are shown in Table 2.

[0054] Table 1

[0055] Properties of feedstock residue Value <![CDATA[Density at 20 °C, g / cm 3 > 0.9872 <![CDATA[Viscosity, mm 2 / s]]> 151.66 Carbon residue, wt% 22.1 Heavy metals, μg / g 83

[0056] Table 2

[0057] Comparative Example 1 Example 1 Example 2 Extraction efficiency, % 52.2 55 56.1 Carbon residue of deasphalted oil, wt% 10.3 6.7 6.4 Heavy metals in deasphalted oil, μg / g 30 11 9 Asphaltene content of deasphalted oil, wt% 0.21 0.07 0.05

[0058] As can be seen from Table 2, by adopting the technical solutions of Embodiment 1 and Embodiment 2 of the present invention, compared with the prior art, the extraction efficiency, the carbon residue amount of the deasphalted oil, the heavy metal amount of the deasphalted oil, and the asphaltene content of the deasphalted oil have all been significantly improved.

[0059] 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 present 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 present invention and its practical applications, so that those skilled in the art can implement and utilize various different exemplary embodiments of the present invention as well as various different selections and changes. Any simple modification, equivalent change, and modification made to the above exemplary embodiments shall fall within the protection scope of the present invention.

Claims

1. A solvent deasphalting extraction column, characterized in that, it includes: A tower body, which is successively provided with a heating and sedimentation section, an extraction section, and a deoiled asphalt collection area from top to bottom inside; an inner cylinder is provided inside the tower body to form an annular space between the inner cylinder and the tower wall, and the deasphalted oil solution after extraction precipitates asphaltenes and resins in the heating and sedimentation section and settles downward in the annular space; Heat exchange tubes, which are spiral and arranged in the annular space, and the heat exchange medium used inside the heat exchange tubes has the same properties as the solvent used for deasphalting inside 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 inside the tower body.

2. The solvent deasphalting extraction column according to claim 1, characterized in that, The heat exchange tubes are arranged in the heating and sedimentation section at the upper part of the annular space; discharge ports are provided at corresponding positions on the upper part of the inner cylinder wall and at corresponding positions of the heat exchange tubes.

3. The solvent deasphalting extraction column according to claim 2, characterized in that, The extraction section is arranged in the inner cylinder in the middle and lower part of the tower body, and 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; a lower feed distributor is provided below the packing for distributing the solvent upward.

4. The solvent deasphalting extraction column 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 residue oil are mixed by a mixer and then introduced into the upper feed distributor; the second solvent is heated and then introduced into the heat exchange tubes from the top as a heat exchange medium for circulating heat exchange; the third solvent is introduced into the lower feed distributor.

5. The solvent deasphalting extraction column according to claim 4, characterized in that, The volume flow rate of the first solvent is 0.6 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.

6. The solvent deasphalting extraction column 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 inner cylinder of the tower body is controlled between 75 and 80°C.

7. The solvent deasphalting extraction column according to claim 1, characterized in that, The heat exchange tubes adopt pipes with a diameter of 10 mm, and the center distance between adjacent tubes in the overall longitudinal section of the heat exchange tubes is 15 mm.

8. The solvent deasphalting extraction column according to claim 1, characterized in that, The heat exchange tubes extend from the upper end of the inner cylinder to the lower end in the annular space, and the heat exchange tubes have: A heat exchange section, which is located at the corresponding position of the heating and sedimentation section at the upper part of the annular space of the tower body for introducing hot solvent; discharge ports are provided at corresponding positions on the upper part of the inner cylinder wall and at corresponding positions of this heat exchange section; A solvent feeding section, which is the pipe section below the heat exchange section for supplementing cold solvent into the hot solvent after heat exchange and using the mixed solvent as the solvent in the extraction section in the inner cylinder.

9. The solvent deasphalting extraction column according to claim 8, characterized in that, The cold solvent supplement pipeline is composed of multiple branch pipes, and the connection ports of the multiple branch pipes to the heat exchange tubes are arranged at different heights, and the multiple branch pipes can be independently controlled for feeding to adjust the height ratio of the heat exchange section to the solvent feeding section.

10. The solvent deasphalting extraction column according to claim 8, characterized in that, the extraction section is arranged in the inner cylinder in the middle and lower part of the tower body, and 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 after mixing from the solvent feeding section upward.

11. The solvent deasphalting extraction column according to claim 10, characterized in that, the solvent includes a fourth solvent, the hot solvent and the cold solvent; the fourth solvent and the raw material residual oil are mixed by a mixer and then introduced into the upper feed distributor; the hot solvent is introduced into the heat exchange tubes from the top as a heat exchange medium, and after heat exchange in the heat exchange section, it continues to flow spirally downward into the solvent feeding section and is mixed with the cold solvent; the mixed solvent is introduced into the lower feed distributor.

12. The solvent deasphalting extraction column according to claim 11, 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 hot solvent is 0.6 times that of the raw material residual oil; the volume flow rate of the cold solvent is 3.4 times that of the raw material residual oil.

13. The solvent deasphalting extraction column according to claim 11, characterized in that, the temperature of the hot solvent is 90 °C, and the temperature of the cold solvent is 73 °C, so as to ensure that the solvent temperature in the extraction section in the inner cylinder of the tower body is controlled between 75 and 80 °C.

14. The solvent deasphalting extraction column according to claim 4 or 11, characterized in that, the first to fourth solvents, the hot solvent and the cold solvent are all butane.

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