Supercritical carbon dioxide catalytic cracking slurry oil mixing device

Abstract

This invention discloses a supercritical carbon dioxide catalytic cracking slurry mixing device, comprising a vertical tank and, from top to bottom, a slurry inlet, a mixing tank, a supercritical carbon dioxide inlet, a supercritical carbon dioxide outlet, and a mixture outlet. The slurry inlet is located at the top of the vertical tank, the supercritical carbon dioxide inlet passes through the tank wall and forms a leak-free connection with the mixing tank, and the mixture outlet is located at the center of the bottom end cap of the vertical tank. The supercritical carbon dioxide outlet is located at the bottom of the vertical tank, above the mixture outlet. The mixing tank is located on the inner wall of the vertical tank and includes an upper cover plate, a lower cover plate, and a mixing cylinder fixed between the upper and lower cover plates. The upper cover plate has a slurry channel hole communicating with the mixing cylinder, and the lower cover plate has a mixture channel hole communicating with the mixing cylinder. This invention overcomes the mixing difficulties caused by the high viscosity and poor fluidity of the slurry, and achieves thorough mixing of the slurry and supercritical carbon dioxide.

Description

Technical Field

[0001] This invention belongs to the field of mixer technology, specifically relating to a supercritical carbon dioxide catalytic cracking slurry mixing device. Background Technology

[0002] Catalytic cracking slurry contains a large amount of aromatics and alkanes. Using it to produce high-value-added products such as needle coke, carbon black, carbon fiber, rubber fillers, plasticizers, and heat transfer oils can significantly increase the added value of the slurry. However, the presence of a large number of solid catalyst particles in the slurry severely limits its high-value utilization. For example, slurry used to produce carbon black or rubber fillers requires a solid content of no more than 500 ppm; slurry used to produce needle coke requires a solid content of no more than 100 ppm; and the requirements for producing carbon fiber are even more stringent, requiring a solid content of less than 20 ppm. Since the content of solid catalyst powder in catalytic cracking slurry is generally between 2000-9000 ppm, the removal of solid particles from the slurry is a prerequisite for high-value utilization.

[0003] The high viscosity, poor fluidity, difficulty in dispersion, and easy solidification at room temperature of oil slurry severely limit the continuous separation of the solid phase. Supercritical carbon dioxide has a very low viscosity, close to that of a gas, and a large diffusion coefficient. Mixing supercritical carbon dioxide with oil slurry greatly reduces the viscosity of the slurry, making liquid-solid separation easier. A mixer is needed to mix oil slurry and supercritical carbon dioxide. Chinese patent CN 211514352 U discloses a dynamic mixer for high-viscosity media, which extrudes the medium in the upper chamber in a spiral shape into the inner cylinder to mix with other media. This can thoroughly and evenly mix the media and solve the problem of dead zones in the stirring device. However, since carbon dioxide only reaches a supercritical state at pressures above 7.38 MPa, the dynamic seal of the mixer suffers severe wear under high pressure, making long-term continuous operation difficult. Chinese patent CN211216214U discloses a static mixer for high-viscosity liquid materials. By adding mixing sections and flow guide sections inside the mixer, the mixing times of the liquid materials are effectively increased. However, due to the poor fluidity of the oil slurry, the flow is difficult and the pressure drop is large during mixing. Summary of the Invention

[0004] To address the problems of flow difficulties, large pressure drop, and difficulty in long-term continuous operation of existing mixers when mixing oil slurry and supercritical carbon dioxide, this invention provides a supercritical carbon dioxide catalytic cracking oil slurry mixing device.

[0005] The supercritical carbon dioxide catalytic cracking slurry mixing device provided by the present invention includes a vertical tank and, from top to bottom, a slurry inlet, a mixing tank, a supercritical carbon dioxide inlet, a supercritical carbon dioxide outlet, and a mixture outlet arranged sequentially along the vertical tank. The slurry inlet is located on the upper part of the tank wall and extends into the interior of the vertical tank. The supercritical carbon dioxide inlet passes through the tank wall of the vertical tank and forms a leak-free communication with the mixing tank. The mixture outlet is located at the center of the bottom end cap of the vertical tank. The supercritical carbon dioxide outlet is located at the lower part of the vertical tank and above the mixture outlet. The mixing tank is located on the inner wall of the vertical tank and includes an upper cover plate, a lower cover plate, and a mixing cylinder fixed between the upper cover plate and the lower cover plate. The space enclosed by the upper cover plate, the lower cover plate, the inner wall of the vertical tank, and the outer wall of the mixing cylinder forms a supercritical carbon dioxide injection space. A supercritical carbon dioxide channel hole is opened on the upper part of the mixing cylinder wall near the upper cover plate. The upper cover plate has a slurry channel hole communicating with the mixing cylinder, and the lower cover plate has a mixture channel hole communicating with the mixing cylinder.

[0006] The supercritical carbon dioxide channel orifice can be round or square, allowing supercritical carbon dioxide entering the supercritical carbon dioxide injection space from the supercritical carbon dioxide inlet to enter the mixing cylinder; the slurry channel orifice allows slurry entering from the slurry inlet to enter the mixing cylinder; the mixture channel orifice allows the mixture of slurry and supercritical carbon dioxide to exit the mixing cylinder. Slurry from the slurry inlet enters the mixing cylinder through the slurry channel orifice, and supercritical carbon dioxide from the injection space enters the mixing cylinder through the supercritical carbon dioxide channel orifice. After mixing in the mixing cylinder, the slurry and supercritical carbon dioxide exit through the mixture channel orifice.

[0007] As a further improvement, to enhance the mixing intensity within the mixing cylinder, a closed cylindrical flow column is coaxially arranged inside the mixing cylinder, forming an annular flow space between the inner wall of the mixing cylinder and the outer wall of the flow column. The diameter of the flow column is preferably 20% to 80% of the diameter of the mixing cylinder. In this case, the supercritical carbon dioxide channel hole is a tangential opening along the wall of the mixing cylinder. Supercritical carbon dioxide enters tangentially into the annular flow space between the mixing cylinder and the flow column. The tangentially entering supercritical carbon dioxide and the vertically entering oil slurry mixture rotate around the flow column, greatly enhancing the mixing intensity and achieving faster mixing of the oil slurry and supercritical carbon dioxide.

[0008] As a further improvement, a tangential inlet guide pipe section can be installed at the inlet of the tangential supercritical carbon dioxide channel orifice, allowing the supercritical carbon dioxide gas flow to enter the mixing cylinder more tangentially. As a preferred option, the inlet guide pipe section is a reduced-diameter pipe, with its diameter decreasing along the supercritical carbon dioxide flow direction. This reduced-diameter pipe can further increase the flow velocity of supercritical carbon dioxide entering the mixing cylinder, improving the flow mixing effect. Furthermore, by increasing the flow velocity, a negative pressure is created at the slurry channel orifice, exerting a suction effect on the slurry and promoting its entry into the mixing cylinder.

[0009] As a further solution, to improve the mixing intensity of oil slurry and supercritical carbon dioxide, the oil slurry channel hole can be set above the tangential supercritical carbon dioxide channel hole. The oil slurry channel hole is arc-shaped along the circumference of the mixing cylinder, and the arc length does not exceed one-quarter of the circumference of the mixing cylinder.

[0010] As a further improvement, in order to slow down the downward flow velocity of the slurry in the mixing cylinder and prolong the mixing time of the slurry and supercritical carbon dioxide in the mixing cylinder, a baffle plate is installed above the flow column near the top cover of the mixing tank. The baffle plate can be annular, with a length not shorter than the arc length of the slurry channel hole and not exceeding half of the circumference of the mixing cylinder, located at the upper quarter to half position of the mixing cylinder.

[0011] As a further improvement, to ensure the mixing effect of oil slurry and supercritical carbon dioxide, multiple supercritical carbon dioxide inlets and mixing boxes can be installed in the vertical tank to continuously mix the oil slurry with supercritical carbon dioxide and reduce the viscosity of the oil slurry to a set value.

[0012] As a further improvement, since the viscosity of the oil slurry gradually decreases and its fluidity gradually improves after continuous mixing with supercritical carbon dioxide, when there are multiple mixing boxes, the individual opening size of the oil slurry channel hole, the gap size between the mixing cylinder and the surrounding column, and the individual opening size of the mixing channel hole gradually decrease from top to bottom as the position of the mixing box moves downward.

[0013] As an optional solution, to enhance the monitoring of the temperature inside the tank, a thermometer can be installed on the tank. The thermometer can be a single-point temperature measuring thermometer such as an expansion type, resistance temperature detector, or thermocouple, or a multi-point temperature measuring device such as a thermocouple, so as to realize the measurement of multiple points inside the tank.

[0014] As an optional solution, an enhanced mixing section can be set below the mixing tank to further promote the mixing of oil slurry and supercritical carbon dioxide. The enhanced mixing section can be a multi-layer wire mesh, a multi-layer staggered grid, or a support-supported packing material with an increased specific surface area. The purpose is to further disperse the initially mixed oil slurry and mix it with supercritical carbon dioxide through a large specific surface area, thereby enhancing the mixing effect.

[0015] As an alternative, to maintain the temperature of the mixture, if the temperature drops too much after the oil slurry and supercritical carbon dioxide are mixed, causing the oil slurry to become less fluid, a heater can be installed below the enhanced mixing section. The heater can be an electric heater or a heating coil, etc., with the aim of maintaining the oil slurry, supercritical carbon dioxide, and their mixture at a suitable temperature.

[0016] The mixture outlet is located at the bottom of the tank, where the mixed mixture is discharged from the tank, thereby reducing viscosity and increasing utilization.

[0017] Supercritical carbon dioxide that is not completely dissolved in the oil slurry overflows from the supercritical carbon dioxide outlet located at the top of the tank. After overflowing, it can be directly vented or pressurized and circulated back to the supercritical carbon dioxide inlet through pipeline to continue dissolving in the oil slurry.

[0018] The present invention has the following beneficial effects:

[0019] 1) The mixing tank can enhance the mixing of oil slurry and supercritical carbon dioxide, improve fluidity, increase mixing intensity and mixing effect, and facilitate the efficient operation of the mixing unit.

[0020] 2) The oil slurry is dispersed by the oil slurry channel holes and mixed with the tangentially dispersed supercritical carbon dioxide in a tangential flow. The continuous rotation and direction change greatly improve the mixing intensity and effect, and achieve full mixing of oil slurry and supercritical carbon dioxide. Multiple mixing boxes ensure the mixing effect.

[0021] 3) The mixer is equipped with a variety of mixing elements. The enhanced mixing section further expands the contact area of ​​the viscosity-reduced slurry with supercritical carbon dioxide, thereby improving the mixing effect over a larger contact area.

[0022] 4) A heater is installed inside the tank to reheat the mixture, compensate for the possible cooling of the material after mixing, and improve the fluidity of the material in the tank.

[0023] 5) The mixer has no moving parts such as stirring elements, which reduces the energy consumption of the system, makes it suitable for high-pressure mixing conditions, and enables the mixer to operate for a long period of time. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the supercritical carbon dioxide catalytic cracking slurry mixing device of the present invention;

[0025] Figure 2 yes Figure 1 Schematic diagram of the structure of the mixing chamber;

[0026] Figure 3 yes Figure 1 Schematic diagram of the upper and middle cover plate structure;

[0027] Figure 4 yes Figure 1 Schematic diagram of the lower cover plate structure;

[0028] Figure 5 yes Figure 1 Schematic diagram of the cross-sectional structure of the mixing box.

[0029] In the diagram: 1-Slurry inlet, 2-Supercritical carbon dioxide outlet, 3-Mixing tank, 4-Supercritical carbon dioxide inlet, 5-Baffle plate, 6-Flow-around column, 7-Vertical tank, 8-Supercritical carbon dioxide inlet, 9-Heater, 10-Mixed mixture outlet, 11-Enhanced mixing section, 12-Mixing tank, 13-Heater, 14-Enhanced mixing section, 15-Lower cover plate, 16-Mixing cylinder, 17-Upper cover plate, 18-Slurry channel hole, 19-Supercritical carbon dioxide channel hole, 20-Supercritical carbon dioxide injection space, 21-Mixed mixture channel hole, 22-Annular flow-around space. Detailed Implementation

[0030] The invention will now be further described with reference to the accompanying drawings.

[0031] like Figure 1 As shown, the supercritical carbon dioxide catalytic cracking slurry mixing device of the present invention includes a vertical tank 7 and slurry inlet 1, mixing box 3, supercritical carbon dioxide inlet 4, enhanced mixing section 14, heater 13, supercritical carbon dioxide inlet 8, mixing box 12, enhanced mixing section 11, heater 9, supercritical carbon dioxide outlet 2 and mixture outlet 10 arranged sequentially from top to bottom along the vertical tank.

[0032] To enhance the blending effect, Figure 1 The device shown has two mixing tanks, two enhanced mixing sections, and two heaters arranged alternately from top to bottom along the axis of the vertical tank 7.

[0033] Combination Figures 2-5As shown in the diagram, the mixing tank 3 is located on the inner wall of the vertical tank 7, and includes an upper cover plate 17, a lower cover plate 15, and a mixing cylinder 16 fixed between the upper and lower cover plates. The upper cover plate 17, the lower cover plate 15, the inner wall of the vertical tank 7, and the outer wall of the mixing cylinder 16 form a supercritical carbon dioxide injection space 20. A flow-around column 6 is provided inside the mixing cylinder 16, forming an annular flow-around space 22 between the inner wall of the mixing cylinder 16 and the outer wall of the flow-around column 6. A supercritical carbon dioxide channel hole 19 is opened at the upper part of the mixing cylinder 16 near the upper cover plate 17. The supercritical carbon dioxide channel hole 19 is a tangential opening along the wall of the mixing cylinder 16, allowing supercritical carbon dioxide entering the supercritical carbon dioxide injection space 20 from the supercritical carbon dioxide inlet 4 to enter the mixing cylinder. The mixing cylinder 16 has an oil slurry channel hole 18 on the upper cover plate 17, which is connected to the mixing cylinder 16. The oil slurry channel hole 18 is located above the supercritical carbon dioxide channel hole 19. The oil slurry channel hole 18 is arc-shaped along the annular flow space 22 inside the mixing cylinder. The oil slurry entering from the oil slurry inlet 1 enters the mixing cylinder 16 through the oil slurry channel hole 18. A flow baffle 5 is provided in the annular flow space 22. The flow baffle 5 is located above the flow column and close to the upper cover plate 17 of the mixing tank. It can slow down the downward flow velocity of the oil slurry in the mixing cylinder 16 and prolong the mixing time of the oil slurry and supercritical carbon dioxide in the mixing cylinder 16. The lower cover plate 15 has a mixture channel hole 21 connected to the mixing cylinder, which allows the mixture of oil slurry and supercritical carbon dioxide to leave the mixing cylinder 16. Oil slurry from oil slurry inlet 1 enters mixing cylinder 16 through oil slurry channel hole 18, and supercritical carbon dioxide from supercritical carbon dioxide injection space 20 enters mixing cylinder 16 through supercritical carbon dioxide channel hole 19. Oil slurry and supercritical carbon dioxide flow around the flow column 6 and mix in mixing cylinder 16. The mixed mixture leaves mixing box 3 through mixture channel hole 10.

[0034] Combined with appendix Figures 1-5 The working process of this invention is described as follows:

[0035] Catalytic cracking slurry enters the vertical tank 7 through slurry inlet 1, and then enters the mixing tank 3 through slurry channel hole 18. Supercritical carbon dioxide enters the mixing tank 3 through supercritical carbon dioxide inlet 4. After mixing in the mixing tank 3, the slurry and supercritical carbon dioxide exit the mixing tank through mixture channel hole 21. The mixture leaving the mixing tank 3 is further mixed in the enhanced mixing section 14, then heated by heater 13 and enters the mixing tank 12, where it is mixed with supercritical carbon dioxide that has entered the mixing tank 12 through supercritical carbon dioxide inlet 8. After leaving the mixing tank 12, the mixture continues to be further mixed in the enhanced mixing section 11, and then heated by heater 9 before exiting the mixing unit from the mixture outlet 10. Unmixed supercritical carbon dioxide is discharged from the supercritical carbon dioxide outlet 2.

Claims

1. A supercritical carbon dioxide catalytic cracking slurry mixing device, characterized in that: The system includes a vertical tank and, from top to bottom, a slurry inlet, a mixing tank, a supercritical carbon dioxide inlet, a supercritical carbon dioxide outlet, and a mixture outlet. The slurry inlet is located on the upper part of the tank wall and extends into the interior of the vertical tank. The supercritical carbon dioxide inlet passes through the tank wall and forms a leak-free connection with the mixing tank. The mixture outlet is located at the center of the bottom end cap of the vertical tank. The supercritical carbon dioxide outlet is located at the lower part of the vertical tank, above the mixture outlet. The mixing tank is located on the inner wall of the vertical tank and includes an upper cover plate, a lower cover plate, and a mixing cylinder fixed between the upper and lower cover plates. The space enclosed by the upper cover plate, the lower cover plate, the inner wall of the vertical tank, and the outer wall of the mixing cylinder forms a [missing information - likely a specific shape or structure]. A supercritical carbon dioxide injection space is formed; a supercritical carbon dioxide channel hole is opened on the upper part of the mixing cylinder wall near the upper cover plate, and an oil slurry channel hole communicating with the mixing cylinder is provided on the upper cover plate, and a mixture channel hole communicating with the mixing cylinder is provided on the lower cover plate; a closed cylindrical flow column is coaxially arranged inside the mixing cylinder, forming an annular flow space between the inner wall of the mixing cylinder and the outer wall of the flow column; the supercritical carbon dioxide channel hole is a tangential opening along the wall of the mixing cylinder; multiple supercritical carbon dioxide inlets and mixing boxes are provided; the individual opening size of the oil slurry channel hole of the mixing box, the gap size between the mixing cylinder and the flow column, and the individual opening size of the mixture channel hole gradually decrease from top to bottom as the position of the mixing box moves downward.

2. The mixing device according to claim 1, characterized in that: The supercritical carbon dioxide inlet is equipped with a unidirectional inlet guide pipe section.

3. The mixing device according to claim 2, characterized in that: The inlet guide pipe section is a reduced-diameter pipe, and the diameter of the reduced-diameter pipe tends to decrease along the flow direction of supercritical carbon dioxide.

4. The mixing apparatus according to any one of claims 1 to 3, characterized in that: The diameter of the flow-around column is 20% to 80% of the diameter of the mixing cylinder.

5. The mixing apparatus according to any one of claims 1 to 3, characterized in that: The oil slurry channel hole is located above the supercritical carbon dioxide channel hole.

6. The mixing apparatus according to claim 5, characterized in that: The oil slurry channel hole is arc-shaped along the circumference of the mixing cylinder.

7. The mixing apparatus according to any one of claims 1 to 3, characterized in that: A flow-blocking plate is installed above the flow-circling column near the top cover of the mixing tank. The flow-blocking plate is circular.

8. The mixing apparatus according to claim 7, characterized in that: The length of the baffle ring does not exceed half of the circumference of the mixing cylinder, and it is located at the upper quarter to half position of the mixing cylinder.

9. The mixing apparatus according to any one of claims 1 to 3, characterized in that: An enhanced mixing section is provided below the mixing tank.

10. The mixing apparatus according to claim 9, characterized in that: A heater is installed below the enhanced mixing section.

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