A coupled transportation method and system for de-oiled bitumen

Abstract

This invention belongs to the field of heavy oil processing technology in petrochemicals, and discloses a coupled conveying method and system for deoiled asphalt. It solves the problem of instantaneous solidification of high softening point deoiled asphalt upon contact with a low-temperature medium, achieving zero external heat load during conveying. The coupled conveying system includes: a vacuum residue main pipe connected to a vacuum residue source, with a first branch and a second branch branch; a first mixer equipped with a deoiled asphalt inlet and a medium inlet, the deoiled asphalt inlet being connected to a deoiled asphalt outlet pipeline; a heat exchanger with a cold-side flow channel and a hot-side flow channel, the inlet of the cold-side flow channel connected to the first branch branch and its outlet connected to the medium inlet of the first mixer, and the inlet of the hot-side flow channel connected to the outlet of the first mixer, allowing heat exchange between the material in the hot-side flow channel and the material in the cold-side flow channel to form a self-heating cycle; and a second mixer, whose inlet is connected to both the hot-side flow channel outlet and the second branch branch, and whose outlet is used to output the final blended material.

Description

Technical Field

[0001] This invention relates to a coupled transportation method and system for deoiled bitumen, belonging to the field of heavy oil processing technology in petrochemicals. Background Technology

[0002] Solvent deasphalting is an important process for the lightening of heavy oil, separating vacuum residue into deasphalted oil and deoiled asphalt through extraction and separation. In recent years, with the widespread application of light hydrocarbon solvents such as n-pentane, the depth of deasphalting has significantly increased, and the softening point of deoiled asphalt has risen sharply. Deep deasphalting processes using n-pentane as a solvent can produce deoiled asphalt with a softening point as high as 175-180℃, remaining a hard solid below 150℃ with extremely poor fluidity, making direct pipeline transportation using conventional centrifugal pumps impossible.

[0003] The following are some existing transportation methods and their drawbacks for this type of high softening point deoiled bitumen: (1) Mechanical propulsion conveying (such as screw extrusion device) has high equipment investment and serious wear, and cannot achieve long-distance conveying; (2) Although viscosity-reducing cracking pretreatment can reduce molecular weight, it has drawbacks such as extremely high energy consumption, coking risk and difficulty in treating by-product gases. (3) Online conveying of solvents has stringent requirements on conveying distance and system pressure; (4) Although the mixing and transportation of external diluent oil (catalytic cracking slurry or light component oil) can reduce viscosity, it brings high operating costs. Taking a solvent deasphalting unit with a capacity of 3.5 million tons / year as an example, the annual cost of diluent is as high as tens of millions to hundreds of millions of yuan.

[0004] More importantly, the receiving temperature of feedstocks (vacuum residue, slurry oil) in downstream hydrotreating units such as slurry beds is usually 140~160℃. Directly mixing solid asphalt with a softening point as high as 177℃ with vacuum residue or slurry oil at 145℃ will cause the asphalt to solidify instantly at the contact interface, forming asphalt blocks, which will then clog the mixer and delivery pipelines.

[0005] In addition, existing technical solutions mostly use a single conveying path, which is difficult to adapt to abnormal working conditions. Once the conveying system malfunctions, the de-oiled asphalt cannot be sent out, forcing the upstream solvent de-oiling unit to shut down urgently, resulting in huge economic losses. Summary of the Invention

[0006] This invention aims to provide a coupled transportation method and system for deoiled asphalt. By recovering and utilizing the high-temperature sensible heat of the deoiled asphalt and adopting downstream raw material graded temperature control technology, the contradiction of instantaneous "solidification deadlock" when high softening point deoiled asphalt comes into contact with low temperature medium is solved, achieving "zero external heat load" in the transportation process and reducing energy consumption and cost.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A coupled conveying system for de-oiled bitumen, comprising: A vacuum residue main pipe is connected to a vacuum residue source, and the vacuum residue main pipe branches into a first branch and a second branch. The first mixer is equipped with a deoiled bitumen inlet and a medium inlet, wherein the deoiled bitumen inlet is connected to the deoiled bitumen outlet pipeline; The heat exchanger is provided with a cold side flow channel and a hot side flow channel. The inlet of the cold side flow channel is connected to the first branch, the outlet of the cold side flow channel is connected to the medium inlet of the first mixer, and the inlet of the hot side flow channel is connected to the outlet of the first mixer, so that the material in the hot side flow channel exchanges heat with the material in the cold side flow channel to form a self-heating cycle. The second mixer has its inlet connected to the hot-side flow channel outlet of the heat exchanger and the second branch; the outlet of the second mixer is configured to output the final material after it has been mixed by its internal components.

[0008] This coupled conveying system utilizes the immense sensible heat inherent in the high-temperature deoiled asphalt as its sole heat source. Through a heat exchanger, it achieves a self-heating cycle, causing the first stream of vacuum residue, which is diverted from the first branch in the vacuum residue main pipe, to heat up to above the asphalt softening point. This results in the asphalt entering the continuous phase of the residue in the first mixer while in a fully molten state. The two are uniformly premixed to form premixed asphalt. Subsequently, when this premixed asphalt is mixed with the second stream of low-temperature vacuum residue diverted from the second branch, its softening point has already dropped below the receiving temperature. Therefore, there is no risk of solidification when the two are mixed in the second mixer, ultimately resulting in a uniform and stable mixture that is then output. This invention achieves physical-level graded flow separation in the depressurized residue main pipe, with one stage serving as a temperature control carrier and the other as a dilution component. It also ingeniously constructs a closed-loop feedback system for the self-recovery of the sensible heat of the deoiled asphalt. This not only utilizes the waste heat of the deoiled asphalt itself to achieve "self-viscosity reduction and self-heating" during the flow process, completely resolving the contradiction of instantaneous "solidification and deadlock" when high softening point deoiled asphalt comes into direct contact with low-temperature media, but also achieves "zero external heat load" throughout the entire process, fundamentally reducing the system's operating energy costs and equipment investment.

[0009] To cope with abnormal operating conditions, the de-oiled bitumen coupling transportation system also includes an auxiliary support subsystem, which includes: A backup mixer is connected in series on the first branch line; An oil slurry feed line is connected to a purified oil slurry source, and the outlet of the oil slurry feed line is connected to the inlet of the standby mixer or the inlet of the second mixer. The purified oil slurry source comes from the catalytic cracking unit. The vacuum residue oil source comes from the atmospheric and vacuum distillation unit.

[0010] The first, second, and standby mixers all employ SK-type static mixers. The first mixer has a deoiled asphalt inlet, a medium inlet, and a premixed asphalt outlet. Its nominal diameter is DN200-300, and it contains an SK-type mixing unit internally, with an external steam jacket or electric heating. The second mixer has a premixed asphalt inlet, a second stream of vacuum residue inlet, a final material outlet, and a purified slurry inlet. Its nominal diameter is DN400-600, and it also contains an internal SK-type mixing unit. The standby mixer has a vacuum residue inlet, a purified slurry inlet, and a mixed vacuum residue outlet. Its nominal diameter is DN200-300, and it also contains an internal SK-type mixing unit, with an external steam jacket or electric heating.

[0011] To ensure more stable conveying, the coupled conveying system also includes: A buffer tank is disposed on the first branch line, and its outlet is connected to the cold side flow channel inlet of the heat exchanger. A feed pump, located downstream of the buffer tank, is configured to increase the pressure of the medium entering the cold-side flow channel.

[0012] A coupled conveying method for de-oiled bitumen, employing the aforementioned coupled conveying system, includes the following steps: Grading steps: The vacuum residue is proportionally diverted to the first branch line and the second branch line through the vacuum residue main pipe to form the first stream of vacuum residue and the second stream of vacuum residue. Heat exchange step: The first stream of vacuum residue is sent into the cold side channel of the heat exchanger and exchanged with the premixed asphalt in the hot side channel to obtain the first stream of vacuum residue after heating. Premixing step: The deoiled asphalt is mixed with the heated first stream of vacuum residue in the first mixer to obtain premixed asphalt, and the premixed asphalt is fed into the hot side channel of the heat exchanger to form a self-heating cycle, wherein the temperature of the heated first stream of vacuum residue is higher than the softening point of the deoiled asphalt. Second mixing step: The premixed asphalt flowing out of the hot side channel of the heat exchanger is mixed with the second stream of vacuum residue oil in the second branch in the second mixer to obtain the final material with a softening point lower than that of the deoiled asphalt. Conveying steps: Conveying the final material. The temperature of the final material is approximately 140℃~165℃.

[0013] To mitigate the risk of supply disruptions along a single transmission route, the method also includes an auxiliary support step, which is executed under abnormal operating conditions. The abnormal operating conditions include heat exchanger or first mixer failure, interruption or insufficient flow of vacuum residue oil supply, system start-up / shutdown or low load operation. The auxiliary support steps include: feeding purified oil slurry into the second mixer and mixing it with the deoiled asphalt to obtain the final material; or... The purified oil slurry and the first stream of vacuum residue are mixed in a standby mixer and then fed into the heat exchanger, and the premixing step, secondary mixing step and conveying step are performed normally.

[0014] To ensure more stable delivery, the first stream of vacuum residue in the heat exchange step is first introduced into a buffer tank for flow stabilization and pressurized using a feed pump before being sent into the cold side channel of the heat exchanger.

[0015] In order to achieve integrated coupling of material flow and heat flow between the solvent deasphalting unit and the downstream hydrogenation unit, eliminate the need for externally purchased diluents and achieve "zero incremental cost" of the conveying medium, the de-oiled asphalt is led out from the de-oiled asphalt outlet pipeline of the solvent deasphalting unit, and the final material is conveyed to the slurry bed hydrogenation unit.

[0016] Furthermore, the temperature of the deoiled bitumen is not lower than its softening point, which is 160℃~200℃, preferably 170℃~185℃.

[0017] Furthermore, the first stream of vacuum residue accounts for 5% to 15% of the total vacuum residue.

[0018] Furthermore, the aromatic hydrocarbon content of the purified oil slurry is ≥50%.

[0019] Compared with the prior art, the present invention has the following advantages: 1. This invention solves the problem of "solidification lock-up" that easily causes instantaneous agglomeration when high softening point hard asphalt is directly mixed with a low temperature receiving medium with a large temperature difference in a first mixer. After the premixed asphalt is cooled down, it is then mixed a second time with a large flow of low temperature vacuum residue from a second branch in a second mixer. This invention achieves uniformity, viscosity reduction, and stable long-distance pumping of high softening point de-oiled asphalt.

[0020] 2. This invention divides the vacuum residue main into a first branch and a second branch for graded transportation and constructs a self-heating closed-loop circulation system consisting of a heat exchanger and a first mixer. Specifically, it utilizes the high-temperature sensible heat released by the premixed asphalt in the hot-side channel to heat the vacuum residue from the first branch in the cold-side channel. This solves the contradiction between the heat required for heating the high-temperature de-oiled asphalt and the high energy consumption of conventional external heating equipment, achieving "zero new external heat load" in the entire modified transportation process. It completely eliminates the need for traditional high-energy-consuming heating furnaces and significantly reduces the overall energy consumption and carbon emissions of the system.

[0021] 3. By adding an auxiliary support subsystem to deal with abnormal operating conditions, this invention solves the major hidden danger that conventional conveying systems relying on a single conveying path are prone to cause the de-oiled asphalt to be unable to be delivered and to cause passive shutdown of upstream equipment when facing non-steady-state scenarios such as sudden interruption of upstream residual oil supply, maintenance of heat exchange equipment, or low-load start-up and shutdown of the unit. This invention achieves conveying under all operating conditions and has high system reliability and availability.

[0022] 4. By directly connecting to the downstream slurry bed hydrogenation unit, the present invention uses its original feed source as the feed for the vacuum residue main pipeline and slurry feed pipeline, thereby improving the coupling between the units, achieving a high degree of integration and unification, eliminating the need to purchase any diluents or additives, significantly reducing costs and operating expenses. Attached Figure Description

[0023] Figure 1 This is a general schematic diagram of the process principle of one embodiment of the deoiled bitumen coupling conveying system described in this invention; Figure 2 This is a schematic diagram of the cold and hot side temperature distribution of one embodiment of the heat exchanger described in this invention; Figure 3 This is a graph showing the heat exchange temperature relationship between the premixed asphalt and the first stream of vacuum residue in an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of the first mixer used in the embodiments of the present invention; Figure 5 This is a schematic diagram of the structure of the second mixer used in this embodiment of the invention; Figure 6 This is a schematic diagram of the backup mixer used in this embodiment of the invention.

[0024] In the diagram: 1. Main depressurized residue pipe; 2. First branch line; 3. Second branch line; 4. Oil slurry feed line; 5. Solvent deasphalting unit; 6. De-oiled asphalt outlet line; 7. First mixer; 71. First flange; 72. Reducing tee; 73. First connecting pipe; 8. Heat exchanger; 9. Second mixer; 91. Second flange; 92. Unit body; 93. Second connecting pipe; 10. Backup mixer; 101. Backup flange; 102. Backup reducing tee; 103. Backup connecting pipe; 11. Buffer tank; 12. De-oiled asphalt inlet; 13. Medium inlet; 14. Premixed asphalt outlet; 15. Premixed asphalt inlet; 16. Second stream of depressurized residue inlet; 17. Purified oil slurry inlet; 18. Final material outlet; 19. Depressurized residue inlet; 20. Mixed depressurized residue outlet; 21. SK type mixing unit. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings.

[0026] Example 1 See Figures 1 to 6 This embodiment provides a coupled conveying system for deoiled asphalt to solve the problem of instantaneous solidification when high softening point deoiled asphalt comes into direct contact with low-temperature materials, thereby achieving stable pumping and long-distance conveying of high softening point deoiled asphalt. The softening point of this deoiled asphalt is 160℃~200℃, preferably 170℃~185℃, and its apparent viscosity at 150℃ is 1000cP~10000cP (static), with a n-pentane asphaltenes content of 30%~60%. This coupled conveying system includes a main conveying system.

[0027] The main conveying system includes a first mixer 7, a heat exchanger 8, a second mixer 9, a vacuum residue main pipe 1, and a buffer tank 11. The inlet of the first mixer 7 is connected to the de-oiled asphalt outlet pipeline 6 of the solvent deasphalting unit 5. The heat exchanger 8 has a hot-side flow channel and a cold-side flow channel; the inlet of the hot-side flow channel is connected to the outlet of the first mixer 7, and the outlet of the cold-side flow channel is connected to the medium inlet 13 of the first mixer 7. The inlet of the second mixer 9 is connected to the outlet of the hot-side flow channel of the heat exchanger 8, and the outlet of the second mixer 9 is connected to the feed inlet of the downstream slurry-bed hydrotreating unit. The vacuum residue main pipe 1 is led out from the atmospheric and vacuum distillation unit and serves as the vacuum residue source; the vacuum residue main pipe 1 is connected sequentially to the buffer tank 11 and the inlet of the cold-side flow channel of the heat exchanger 8 via a first branch line 2, and is connected to the inlet of the second mixer 9 via a second branch line 3. The buffer tank 11 is equipped with a feed pump, which is used to increase the pressure of the first stream of vacuum residue in the first branch 2 and stably send the first stream of vacuum residue into the heat exchanger 8.

[0028] The heat exchanger 8 is a fixed tube sheet heat exchanger 8, with a hot side inlet temperature of ≥240℃, a hot side outlet temperature of 210℃~230℃, a cold side inlet temperature of 140℃~160℃, and a cold side outlet temperature of 205℃~220℃.

[0029] See Figure 4 The first mixer 7 consists of a first flange 71, a reducing tee 72, and a first connecting pipe 73. The two ports of the reducing tee 72 connect the flange and the connecting pipe respectively, and the third port of the reducing tee 72 serves as the medium inlet 13. The reducing tee 72 is of type DN250 / DN200. The port of the first flange 71 serves as the de-oiled asphalt inlet 12, and the first flange 71 is of type WN250-600RF. The first connecting pipe 73 contains an SK-type mixing unit 21, and its outlet serves as the premixed asphalt outlet 14. The first connecting pipe 73 has a specification of φ273*10, and its shell is equipped with a steam jacket or electric heating to maintain a mixing temperature ≥200℃.

[0030] See Figure 5The second mixer 9 consists of a second flange 91, a body 92, and a second connecting pipe 93 connected in sequence. The port of the second flange 91 serves as the second inlet 16 for the vacuum residue oil stream; the model of the second flange 91 is WN400-600RF. The body 92 is equipped with a premixed asphalt inlet 15 and a purified slurry inlet 17. The body 92 is tapered at the connection with the second flange 91, with a nominal diameter of DN400 / DN500. The second connecting pipe 93 houses an SK-type mixing unit 21, and its outlet serves as the final material outlet 18; the specification of the second connecting pipe 93 is φ508*12.5.

[0031] See Figure 6 The backup mixer 10 consists of a backup flange 101, a backup reducing tee 102, and a backup connecting pipe 103. The two ports of the backup reducing tee 102 are connected to the backup flange 101 and the backup connecting pipe 103, respectively. The third port of the backup reducing tee 102 serves as the purified slurry inlet 17. The backup reducing tee 102 is of model DN200 / DN100. The port of the backup flange 101 serves as the vacuum residue inlet 19. The backup flange 101 is of model WN200-600RF. The backup connecting pipe 103 houses an SK-type mixing unit 21. The outlet of the backup connecting pipe 103 serves as the mixed vacuum residue outlet 20. The specifications of the backup connecting pipe 103 are φ219.1*12.5.

[0032] This embodiment also provides a method for coupled transport of de-oiled asphalt using the above-described coupled transport system. This method employs a main transport scheme to achieve coupled transport of high softening point de-oiled asphalt. The main transport scheme includes the following steps: Grading Steps: The vacuum residue is divided into two streams via a first branch line 2 and a second branch line 3, resulting in a first vacuum residue stream and a second vacuum residue stream. The first vacuum residue stream comprises 5%–15% of the total vacuum residue, preferably 8%–12%, while the second vacuum residue stream comprises 85%–95% of the total vacuum residue. The flow rate of the two streams is controlled by a structure such as valves and pipes. The vacuum residue has a temperature of 140℃–160℃, a density of 0.95 g / cm³–1.10 g / cm³, a viscosity of 300 cP–2000 cP at 145℃, preferably 550 cP–600 cP, and a carbon residue of 15%–30%.

[0033] Heat exchange process: The first stream of vacuum residue is exchanged with premixed asphalt in heat exchanger 8 to obtain a heated first stream of vacuum residue and a cooled premixed asphalt. The first stream of vacuum residue is heated to 205℃~220℃, significantly higher than the softening point of the deoiled asphalt (≥170℃). The premixed asphalt is cooled to 210℃~230℃, while still maintaining good fluidity. Heat exchanger 8 is a self-heating heat exchanger, utilizing the high sensible heat of the deoiled asphalt itself to heat part of the vacuum residue to a temperature above the asphalt softening point, requiring no external heat load. A rough temperature distribution curve for the cold and hot sides of heat exchanger 8 can be found in [reference needed]. Figure 2 In the graph, the red line represents the cold side, the blue line represents the hot side, and the horizontal axis corresponds to the tube side of heat exchanger 8. The heat exchange temperature relationship curve between the premixed asphalt and the first stream of vacuum residue is shown in [reference needed]. Figure 3 In the diagram, the red line represents the temperature of the premixed asphalt, and the black line represents the temperature of the first stream of vacuum residue.

[0034] Premixing Step: The deoiled asphalt exiting the deoiled asphalt outlet pipeline 6 is premixed with the first stream of vacuum residue after heating in the first mixer 7 to obtain premixed asphalt. The temperature of the premixed asphalt is ≥240℃, approximately 245℃~255℃, the softening point is 110℃~120℃, and the viscosity at 150℃ is 400cP~450cP, fully meeting the pumping requirements. This deoiled asphalt is a high-temperature, high-softening-point deoiled asphalt, with a temperature ≥270℃, pressure ≥1.6MPa, and a softening point ≥170℃ (typical value 177℃). The viscosity at this temperature is 1100cP~1200cP, and this deoiled asphalt carries a large amount of high-temperature sensible heat. The temperature difference between this deoiled asphalt and the first stream of vacuum residue after heating is within 50℃~70℃. The temperature of the first stream of vacuum residue after heating is approximately 20℃~50℃ higher than the softening point of the deoiled asphalt. Since the temperature of the first batch of depressurized residue oil and the temperature of the deoiled asphalt are both higher than the softening point of the asphalt, the asphalt is in a completely molten state when they come into contact. Under the action of high shear force, the deoiled asphalt is dispersed into fine droplets and uniformly suspended in the continuous phase of the residue oil to form premixed asphalt.

[0035] The second mixing step involves mixing the cooled premixed asphalt with the second stream of vacuum residue in the second mixer 9 to obtain the final material. The final material has a temperature of approximately 145℃~165℃, and its softening point is lower than that of the deoiled asphalt. Since the softening point of the premixed asphalt (110℃~120℃) is lower than the temperature of the second stream of vacuum residue (140℃~160℃), there is no risk of solidification during mixing, resulting in a homogeneous and stable mixture.

[0036] Conveying steps: The final material is sent to the downstream slurry bed hydrogenation unit, and the conveying temperature is maintained at 140℃~165℃.

[0037] Example 2 See Figure 1The difference between this embodiment and Embodiment 1 is that the coupled conveying system in this embodiment adds an auxiliary support subsystem to the main conveying system to deal with abnormal operating conditions. These abnormal operating conditions refer to non-steady-state conditions such as equipment failure and maintenance of the main conveying system (e.g., failure of heat exchanger 8, mixer, pump, etc.), interruption or insufficient flow of vacuum residue oil supply, and start-up, shutdown, or low-load operation of the unit.

[0038] The auxiliary support subsystem includes a standby mixer 10 and a slurry feed line 4 connected to the purified slurry source. The standby mixer 10 is connected in series on the first branch 2 of the vacuum residue main 1 and is connected upstream of the buffer tank 11. The standby mixer 10 maintains an operating temperature of 140℃~160℃. The slurry feed line 4 is led out from the catalytic converter and serves as the purified slurry source. After desolidification treatment, it is connected to the inlet of the standby mixer 10 or directly to the inlet of the second mixer 9 via a slurry transfer pump and a slurry shut-off valve.

[0039] Regarding the self-heating heat exchanger 8 described in this invention, in the initial stage of operation or the initial stage of system operation, the viscosity of the initially de-oiled asphalt is low and it has its own slag reduction properties. That is, the viscosity of the initially produced de-oiled asphalt is not high, and it can be transported even without mixing. Therefore, at this time, there is no need for much self-heating at the heat exchanger 8. However, as the system gradually operates and gradually drives the device to heat up, the system will slowly heat up. Once the system stabilizes, self-heating heat exchange can be achieved. That is, the premixed asphalt (obtained by premixing the de-oiled asphalt with the first stream of vacuum residue oil after heating in the first mixer 7) exchanges heat with the first stream of vacuum residue oil, thus completely eliminating the need for external heat load.

[0040] This embodiment also provides a method for coupled transport of deoiled asphalt using the above-described coupled transport system. This method employs a main transport scheme and a backup transport scheme to achieve coupled transport of high softening point deoiled asphalt. The main transport scheme is the scheme described in Embodiment 1. The backup transport scheme is only executed under abnormal operating conditions.

[0041] The backup delivery plan includes the following steps: Auxiliary support steps: Purified oil slurry is fed into the second mixer 9 for mixing. At this time, the purified oil slurry is mixed with deoiled asphalt or premixed asphalt in the second mixer 9, obtaining the final material with a temperature of approximately 140℃~160℃. Alternatively, the purified oil slurry and the first stream of vacuum residue are mixed in the standby mixer 10 and then fed into the heat exchanger 8, following the normal conveying paths corresponding to the premixing, secondary mixing, and conveying steps in the main conveying scheme. During mixing, the purified oil slurry is introduced at a ratio of 5%~20% of the mass of deoiled asphalt. The feed temperature of the purified oil slurry is 140℃~280℃, the aromatic content is ≥50%, preferably ≥60%, the density is 1.00g / cm³~1.10g / cm³, and the viscosity at 150℃ is 50cP~300cP, exhibiting excellent dissolving and dispersing ability for asphalt.

[0042] For the scheme of directly feeding purified oil slurry into the second mixer 9 for mixing, the purified oil slurry has a high temperature, so it can directly and fully contact and mix with the high softening point deoiled asphalt, without needing to activate the heat exchanger 8 and the first mixer 7 related to the vacuum residue. For the scheme of mixing in the standby mixer 10, the standby mixer 10 does not need to be used when the vacuum residue supply is normal, or in other words, the vacuum residue normally passes through the standby mixer 10, and purified oil slurry is not injected into the standby mixer 10; only when the vacuum residue supply is interrupted or the ratio is abnormal, when the vacuum residue pressure is insufficient, that is, when the system is in an abnormal operating condition, purified oil slurry is injected into the standby mixer 10 to premix with the small amount of the first stream of vacuum residue that may be present there, and then it can be transported according to the established conventional process in the main conveying scheme. For example, it can enter the buffer tank 11 and the heat exchanger 8 in sequence, and then be mixed with the deoiled asphalt in the first mixer 7 to obtain premixed asphalt and exchange heat with the premixed asphalt, and finally be mixed in the second mixer 9 to obtain the final material and output. By utilizing the affinity of the aromatic components of the slurry for asphaltene and the low viscosity of the slurry itself, the high softening point asphalt is rapidly softened and dispersed to form a uniform final material.

[0043] The final material is sent to the downstream slurry bed hydrogenation unit. Since the slurry is the original design feedstock for the downstream unit, this solution completely avoids the need to purchase diluents externally, and as a backup measure, it requires only minimal equipment investment to provide transportation assurance for the entire plant under critical operating conditions.

[0044] The fundamental purpose of this invention is to establish a comprehensive, low-cost, and highly reliable de-oiled asphalt transportation solution that uses existing raw materials as the main source and another existing raw material as a backup, without increasing any purchased media or external heat load, thereby fundamentally breaking through the bottleneck of high softening point de-oiled asphalt transportation.

[0045] Example 3 This embodiment uses the application of the above-mentioned coupled conveying system to a 3.5 million tons / year solvent deasphalting unit 5 under construction as an example for illustration.

[0046] A new 3.5 million tons / year solvent deasphalting unit (5) is being built in a certain integrated refining and chemical project, using n-pentane as the solvent, with a designed deasphalting yield of 34%. Downstream of this unit is a slurry-bed hydrogenation unit, originally designed to use vacuum residue as feedstock at a receiving temperature of 145℃. The designed softening point of the deasphalted asphalt is 177℃, and it is discharged from the bottom of the asphalt stripping tower through the deasphalted asphalt outlet pipeline (6) at a temperature of 274℃, a pressure of 1.66 MPa, and a viscosity of 1145 cP (at 274℃). The vacuum residue arrives from outside the boundary area at a temperature of 145℃ and a viscosity of 592 cP.

[0047] The design parameters of its main conveying scheme are as follows: project Flow rate (t / h) Temperature (°C) Pressure (MPa) Viscosity (cP) Softening point (°C) Deoiled Asphalt 142 274→163 1.66→0.9 1145→569 177 (Pure deoiled bitumen) Total amount of vacuum residue 930 145 ≥0.5 592 - First stream of vacuum residue (10%) 97 145→205 - 592→54 - Second stream of vacuum residue (90%) 833 145 - 592 - The main conveyor system equipment selection is as follows: Heat exchanger 8: Fixed tube sheet type, heat exchange area 2329m², hot side 245℃→205℃, cold side 145℃→205℃.

[0048] First mixer 7: Static mixer, SK type, DN250, with steam jacket.

[0049] Second mixer 9: Static mixer, SK type, DN500, with steam jacket.

[0050] The results of the process simulation are as follows: Premixed asphalt softening point: 117℃.

[0051] Premixed asphalt viscosity at 245℃: 268 cP.

[0052] Final material viscosity at 163°C: 569 cP.

[0053] Flow condition throughout the line: turbulent, meeting the conveying requirements.

[0054] The design parameters for its backup transportation scheme are as follows: project Flow rate (t / h) Temperature (°C) Design pressure (MPa) Deoiled Asphalt 142 274 1.66 Purified oil slurry 0-30 150 1.0 The equipment selection for the auxiliary support subsystem is as follows: Backup mixer 10: Static mixer, SK type, DN200, with steam jacket (1.3MPa saturated steam heating), material is 316L (on the asphalt contact side), design flow range is 0~135t / h (meeting the full conveying requirements).

[0055] Typical application scenarios under abnormal operating conditions are as follows: Scenario A: Overhaul of Heat Exchanger 8 During the overhaul of heat exchanger 8, the main conveying scheme was not operational. The backup conveying scheme was activated: the deoiled bitumen and oil slurry were directly mixed in the second mixer 9 and then sent to the downstream slurry bed hydrogenation unit via the original process.

[0056] Scenario B: Disruption of vacuum residue supply An upstream atmospheric and vacuum distillation unit experienced a sudden malfunction, resulting in a two-hour interruption or a sudden reduction in vacuum residue oil supply. The main conveying system could not operate due to the lack of residue oil medium. Supplementing with some slurry oil was necessary to maintain delivery, buy time for upstream repairs, and prevent the deoiled asphalt pipeline from solidifying.

[0057] Scenario C: Equipment start-up and shutdown In the initial stage of plant startup, the vacuum residue oil system has not yet established a stable circulation; at the end of the plant shutdown, the residue oil pipeline has been cleared and cleaned. During this stage, the backup transportation plan is activated, using oil slurry as the medium for transporting deoiled bitumen, to achieve a smooth transition during startup and shutdown.

[0058] The advantages of this invention are as follows: 1. It fundamentally solved the technical contradiction of "low temperature reception - high temperature softening point"; The fact that the downstream receiving temperature (140~160℃) is lower than the softening point of the deoiled asphalt (≥170℃) is an objective process constraint. The main conveying scheme of this invention, through staged premixing and local high-temperature compensation, transforms the high-temperature deoiled asphalt into premixed asphalt with a softening point of 110℃~120℃ before contacting the low-temperature vacuum residue oil; the backup conveying scheme utilizes the chemical affinity of the aromatic components of the oil slurry for asphaltene, and can also achieve asphalt softening and dispersion at temperatures below the softening point.

[0059] 2. It has pioneered a "self-heating" technology approach, with zero external heat load and low energy consumption; The main transportation scheme proposes for the first time to utilize the high-temperature sensible heat of the deoiled bitumen itself to heat the vacuum residue. Based on a deoiled bitumen flow rate of 142 t / h and a temperature drop of 52℃, the released heat is 1.55 × 10⁻⁶. 7 This amount of kJ / h is sufficient to preheat 97t / h of vacuum residue from 145℃ to 205℃. The additional heat load is zero, and the overall energy consumption is reduced by more than 65% compared to existing viscosity-reducing cracking methods.

[0060] 3. A full-condition transportation support system has been established, which has greatly improved the reliability of the equipment operation; This invention introduces the concept of primary / backup dual-path conveying to the field of de-oiled bitumen conveying for the first time. Under normal operating conditions, the primary conveying scheme operates efficiently at extremely low cost; under abnormal operating conditions, the backup conveying scheme maintains conveying using a small amount of oil slurry as the medium, avoiding plant shutdowns caused by the inability to deliver de-oiled bitumen. Reliability analysis showed that after adding the auxiliary support subsystem, the availability of the coupled de-oiled bitumen conveying system increased from 92% to over 99.5%.

[0061] 4. Zero additional media costs, significantly reducing operating expenses; The mixing media (vacuum residue and purified slurry) used in the main and backup conveying schemes of this invention are the original raw materials for downstream slurry-bed hydrotreating units, eliminating the need to purchase any diluents or additives and thus avoiding any additional processing burden on downstream units. Taking a 3.5 million tons / year solvent deasphalting unit as an example: if a traditional dilution oil scheme (with a blending ratio of 5% to 10%) is used, the annual diluent cost would be as high as 0.5 billion to 5 billion yuan; however, the scheme of this invention can completely save this cost.

[0062] 5. Deep coupling between units enhances the level of integrated refining and chemical production; This invention organically couples the material flow and heat flow of the solvent deasphalting unit 5 with those of the downstream slurry bed hydrogenation unit: (1) Material flow: The raw materials of the downstream unit are directly used as the conveying medium, reducing the need for intermediate tank areas and conveying equipment; (2) Heat flow (main transportation scheme): High-temperature asphalt waste heat is used to preheat residual oil to realize energy cascade utilization; (3) Backup route: The raw materials of another set of equipment serve as emergency backup, forming a mutual assistance network between the equipment.

[0063] 6. The system is simple and has an extremely short investment payback period; The main delivery solution requires only a few additional pieces of equipment, such as heat exchanger 8 and mixer, to the existing process, with an investment of approximately RMB 1.8 million to 2.5 million. Savings on diluent alone will allow the investment to be recovered within 1-2 months. The backup delivery solution requires only the addition of a small mixer, pump, and pipelines, with an investment of less than RMB 500,000. It provides full-condition operational capability, offering extremely high cost-effectiveness. A single successful operation avoiding downtime will recover the entire investment.

[0064] The embodiments of the present invention have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention is not limited to the specific embodiments described above; these embodiments are merely illustrative and not limiting. Those skilled in the art, under the guidance of the present invention, can make many modifications without departing from the spirit and scope of the claims, and all such modifications fall within the scope of protection of the present invention.

Claims

1. A coupled conveying system for de-oiled bitumen, characterized in that, include: A vacuum residue main pipe (1) is connected to a vacuum residue source, and the vacuum residue main pipe (1) branches into a first branch (2) and a second branch (3). The first mixer (7) is equipped with a de-oiled bitumen inlet (12) and a medium inlet (13), wherein the de-oiled bitumen inlet (12) is connected to the de-oiled bitumen outlet pipeline (6); The heat exchanger (8) is provided with a cold side flow channel and a hot side flow channel. The inlet of the cold side flow channel is connected to the first branch (2), the outlet of the cold side flow channel is connected to the medium inlet (13) of the first mixer (7), and the inlet of the hot side flow channel is connected to the outlet of the first mixer (7), so that the material in the hot side flow channel and the material in the cold side flow channel exchange heat to form a self-heating cycle. The inlet of the second mixer (9) is connected to the hot side outlet of the heat exchanger (8) and the second branch (3); the outlet of the second mixer (9) is configured to output the final material after it has been mixed by its internal components.

2. The coupling conveying system according to claim 1, characterized in that, It also includes an auxiliary support subsystem, which includes: A backup mixer (10) is connected in series on the first branch (2); The oil slurry feed line (4) is connected to the purified oil slurry source, and the outlet of the oil slurry feed line (4) is connected to the inlet of the standby mixer (10) or the inlet of the second mixer (9).

3. The coupling conveying system according to claim 1, characterized in that, Also includes: A buffer tank (11) is provided on the first branch (2), and its outlet is connected to the cold side flow channel inlet of the heat exchanger (8); A feed pump, located downstream of the buffer tank (11), is configured to increase the pressure of the medium entering the cold side flow channel.

4. A coupled conveying method for de-oiled bitumen, comprising using the coupled conveying system as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Grading steps: The vacuum residue is diverted to the first branch line (2) and the second branch line (3) in proportion through the vacuum residue main pipe (1) to form the first stream of vacuum residue and the second stream of vacuum residue. Heat exchange steps: The first stream of vacuum residue is sent into the cold side channel of the heat exchanger (8) to exchange heat with the premixed asphalt in the hot side channel to obtain the first stream of vacuum residue after heating. Premixing step: The deoiled asphalt is mixed with the first stream of vacuum residue after heating in the first mixer (7) to obtain premixed asphalt, and the premixed asphalt is sent into the hot side channel of the heat exchanger (8) to form a self-heating cycle, wherein the temperature of the first stream of vacuum residue after heating is higher than the softening point of the deoiled asphalt. Second mixing step: The premixed asphalt flowing out of the hot side channel of the heat exchanger (8) is mixed with the second stream of vacuum residue oil in the second branch (3) in the second mixer (9) to obtain the final material with a softening point lower than that of the deoiled asphalt; Conveying steps: Conveying the final material.

5. The method according to claim 4, characterized in that, It also includes auxiliary support steps, which are executed under abnormal operating conditions. The abnormal operating conditions include malfunction of heat exchanger (8) or first mixer (7), interruption or insufficient flow of vacuum residue oil supply, system start-up and shutdown or low load operation; The auxiliary support steps include: feeding purified oil slurry into the second mixer (9) and mixing it with the deoiled asphalt to obtain the final material; or, The purified oil slurry and the first stream of vacuum residue are mixed in the standby mixer (10) and then sent to the heat exchanger (8), and the premixing step, the secondary mixing step and the conveying step are performed normally.

6. The method according to claim 4, characterized in that, Before the first stream of vacuum residue enters the heat exchanger (8), it is first introduced into the buffer tank (11) for flow stabilization and pressurized by the feed pump, and then sent into the cold side flow channel of the heat exchanger (8).

7. The method according to claim 4, characterized in that, The de-oiled asphalt outlet pipeline (6) of the self-solvent de-oiling device (5) is led out, and the final material is transported to the slurry bed hydrogenation device.

8. The method according to claim 4, characterized in that, The temperature of the deoiled bitumen is not lower than its softening point, which is 160℃~200℃.

9. The method according to claim 4, characterized in that, The first stream of vacuum residue accounts for 5% to 15% of the total vacuum residue.

10. The method according to claim 5, characterized in that, The purified oil slurry has an aromatic hydrocarbon content of ≥50%.

Images