Supercritical carbon dioxide catalytic cracking slurry mixing device

Abstract

The application discloses a supercritical carbon dioxide catalytic cracking oil slurry mixing device, which comprises a vertical tank body, a supercritical carbon dioxide inlet, an oil slurry inlet, a flow guide cylinder, a spiral guide vane, a supercritical carbon dioxide outlet and a mixture outlet; the flow guide cylinder is arranged in the vertical tank body and is composed of a positive conical cylinder with a small upper end and a large lower end at the upper part and a cylindrical cylinder or an inverted conical cylinder with a large upper end and a small lower end at the lower part; the oil slurry inlet is arranged on the top head of the vertical tank body and is coaxially arranged with the vertical tank body and the flow guide cylinder, and the supercritical carbon dioxide inlet is arranged in the middle upper part of the vertical tank body; an annular space is formed between the outer wall of the flow guide cylinder and the inner wall of the vertical tank body, and the spiral guide vane is arranged around the flow guide cylinder in the annular space; the supercritical carbon dioxide outlet is arranged at the lower part of the vertical tank body and above the mixture outlet, and the mixture outlet is arranged at the bottom of the vertical tank body. The application overcomes the mixing difficulty caused by the large viscosity and poor flowability of the oil slurry and realizes the full mixing of the oil slurry and the 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 and 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 ability to achieve continuous solid-phase separation. 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 significantly reduces the viscosity of the slurry, making liquid-solid separation easier. A mixer is required when mixing 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 this invention includes a vertical tank and, arranged from top to bottom along the vertical tank, a supercritical carbon dioxide inlet, a slurry inlet, a guide tube, a spiral guide vane, a supercritical carbon dioxide outlet, and a mixture outlet. The vertical tank is generally cylindrical. The guide tube is located inside the vertical tank and is generally circular and hollow, consisting of two parts: the upper part is a positive cone with a smaller upper end and a larger lower end, and the lower part is a cylindrical tube or an inverted cone with a larger upper end and a smaller lower end. The lower end of the positive cone is also the upper end of the lower cavity. The slurry inlet is located on the top end cap of the vertical tank and is coaxially arranged with the vertical tank and the guide tube. The supercritical carbon dioxide inlet is located in the upper middle part of the vertical tank. An annular space is formed between the outer wall of the guide tube and the inner wall of the vertical tank, and a spiral guide vane is arranged around the guide tube in the annular space. The supercritical carbon dioxide outlet is located in the lower part of the vertical tank and above the mixture outlet, and the mixture outlet is located at the bottom of the vertical tank.

[0006] Supercritical carbon dioxide enters the vertical tank directly through the supercritical carbon dioxide inlet located in the upper part of the tank. It mixes with the oil slurry that enters the vertical tank through the oil slurry inlet in the annular space as it rotates downward along the spiral guide vanes. The mixture is discharged through the mixture outlet at the bottom of the vertical tank, and the undissolved supercritical carbon dioxide is discharged through the supercritical carbon dioxide outlet.

[0007] As one improvement, a dispersion chamber is provided between the outer side of the spiral guide vane and the inner wall of the vertical tank. The dispersion chamber is an annular cavity with its upper and lower sides closed. Its outer side wall is the cylindrical wall of the vertical tank. The supercritical carbon dioxide inlet is located on the outer side wall of the dispersion chamber and communicates with the dispersion chamber. A dispersion hole is provided on the inner side wall of the dispersion chamber, through which supercritical carbon dioxide enters the annular space.

[0008] As a second improvement, the supercritical carbon dioxide inlet extends into the guide tube and communicates with the guide tube. The lower part of the guide tube wall is provided with injection holes along the circumference, and the supercritical carbon dioxide enters the annular space through the injection holes.

[0009] As a third improvement, the above two improvements are combined, and in this case, there are two supercritical carbon dioxide inlets. One is connected to the dispersion chamber, and supercritical carbon dioxide enters the annular space through the dispersion holes; the other is connected to the guide tube, and supercritical carbon dioxide enters the annular space through the injection holes.

[0010] When the lower cavity of the guide tube is a cylindrical tube, the diameter of the cylindrical tube should preferably be 0.5 to 0.9 times the diameter of the vertical tank. If the lower part of the guide tube is an inverted cone, the diameter of the large end of the inverted cone should preferably be 0.5 to 0.9 times the diameter of the vertical tank, and the diameter of the small end of the inverted cone should preferably be 0.2 to 0.8 times the diameter of its large end. The slurry inlet, the guide tube, and the vertical tank are coaxially arranged. The slurry entering from the slurry inlet is dispersed into the annular space between the vertical tank and the guide tube by the action of the conical tube. As a preferred option, the lower part of the guide tube should preferably be an inverted cone. The main purpose of the lower inverted cone is to allow for a gradually increasing volume after the slurry absorbs supercritical carbon dioxide.

[0011] As an improvement, a receiving tray can be installed at the top of the conical cylinder, facing the slurry inlet. The slurry entering from the inlet first enters the receiving tray, and after the tray is full, the slurry overflows onto the guide tube. This allows the slurry to enter the annular space between the guide tube and the inner wall of the vertical tank more evenly. The receiving tray can be fixed to the top of the conical cylinder by a support, or the top of the conical cylinder can be directly machined into a platform-shaped receiving tray.

[0012] The axial height of the dispersion chamber should be 0.5 to 0.9 times the height of the lower part of the guide tube, and the radial width of the dispersion chamber should be 0.05 to 0.3 times the diameter of the vertical tank.

[0013] The dispersion holes and / or injection holes can be round holes, slits, or square holes, allowing supercritical carbon dioxide to enter the dispersion chamber and / or the guide tube from the supercritical carbon dioxide inlet into the annular space between the guide tube and the inner wall of the vertical tank. From a manufacturing perspective, the openings should preferably be round holes with a diameter of 5–50 mm; the slit width should be 3–40 mm, and the length should be 5–50 mm.

[0014] The spiral guide vanes are spiral-shaped, with a pitch preferably between 0.05 and 0.2 times the diameter of the vertical tank. The spiral guide vanes create a spiral channel in the annular space between the inner wall of the vertical tank and the guide tube. After the oil slurry enters the vertical tank through the oil slurry inlet, it is evenly dispersed into the spiral channel under the influence of gravity and the dispersion effect of the upper conical tube of the guide tube. Simultaneously, supercritical carbon dioxide enters the dispersion chamber and / or the guide tube through the supercritical carbon dioxide inlet, and is dispersed into the spiral channel through the dispersion holes in the dispersion chamber and / or the injection holes on the lower wall of the guide tube. On the spiral guide vanes, the oil slurry continuously swirls around the guide tube from top to bottom, constantly contacting the dispersed supercritical carbon dioxide. During the spiral motion, the oil slurry and supercritical carbon dioxide continuously collide and change direction, greatly enhancing the mixing time and intensity of the oil slurry within the vertical tank, ensuring a good mixing effect and effectively reducing the viscosity of the mixture.

[0015] As a further improvement, considering that the mixing of oil slurry and supercritical carbon dioxide requires a certain amount of time, and that concentrated entry of supercritical carbon dioxide can cause local over-dissolved carbon dioxide, resulting in a poor mixing effect, the release of supercritical carbon dioxide can be controlled by adjusting the location and number of dispersion holes on the inner wall of the supercritical carbon dioxide dispersion chamber and / or injection holes on the lower wall of the guide tube to further enhance the mixing effect. Specifically, the dispersion holes on the inner wall of the dispersion chamber and / or injection holes on the lower wall of the guide tube are spirally distributed along the spiral direction of the spiral guide vane and located above the spiral guide vane, generally 10–100 mm above it. The opening direction of the dispersion holes and / or injection holes is aligned with the spiral direction of the spiral guide vane, ensuring that the supercritical carbon dioxide enters in the direction of oil slurry flow, thus promoting the flow of the oil slurry.

[0016] As a further improvement, to further enhance the space utilization within the vertical tank and increase mixing intensity, the pitch of the spiral guide vanes should gradually decrease from top to bottom. This design takes into account that the first half of the oil slurry dissolves less carbon dioxide and has poor fluidity; a larger pitch can increase the fluidity of the oil slurry. In the second half, as supercritical carbon dioxide gradually dissolves, the fluidity of the oil slurry improves, allowing the pitch to be reduced. This better utilizes the internal space of the vertical tank, increases the contact time between the oil slurry and supercritical carbon dioxide, and achieves a better mixing effect.

[0017] As a further improvement, an enhanced mixing element is installed below the guide tube and before the supercritical carbon dioxide outlet. The purpose of installing the enhanced mixing element is to further promote the mixing of oil slurry and supercritical carbon dioxide. The enhanced mixing element 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 use the large specific surface area to disperse the oil slurry and mix it with the supercritical carbon dioxide, thereby enhancing the mixing effect.

[0018] The supercritical carbon dioxide outlet is located at the bottom of the vertical tank and above the mixture outlet, allowing supercritical carbon dioxide that has not been completely dissolved in the oil slurry to overflow. After overflowing, it can be directly discharged or pressurized and circulated back to the supercritical carbon dioxide inlet through pipeline to continue dissolving in the oil slurry.

[0019] The mixture outlet is located at the bottom of the vertical tank, either at the bottom of the side wall or at the bottom end, allowing for further utilization of the mixed and viscosity-reduced slurry.

[0020] Further improvements can be made by setting the bottom of the vertical tank to be conical, so that the liquid mixture is stored in the conical hopper under the action of gravity, making it easier for the mixture to leave from the mixture outlet.

[0021] The present invention has the following beneficial effects:

[0022] 1) The oil slurry and supercritical carbon dioxide are dispersed and mixed in contact. Under the guiding action of the spiral guide vanes in the annular space, the gravity of the oil slurry and the impact force of the supercritical carbon dioxide are fully utilized to increase the fluidity of the oil slurry and improve the mixing effect. This overcomes the shortcomings of high viscosity and poor fluidity of the oil slurry and achieves the effect of mixing and reducing viscosity.

[0023] 2) The use of spiral guide vanes increases the contact time and contact intensity between the oil slurry and supercritical carbon dioxide; when the lower part of the guide tube is a cone, the annular space with the radial width gradually increasing from top to bottom can provide space for the mixture of oil slurry and supercritical carbon dioxide to expand, resulting in smooth flow and low flow pressure drop.

[0024] 3) The vertical tank 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 long-cycle operation of the mixing device. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of one structure of the mixing device of the present invention;

[0026] Figure 2 This is another schematic diagram of the mixing device of the present invention;

[0027] Figure 3 It is a diagram showing the arrangement of the dispersion holes and / or injection holes.

[0028] In the diagram: 1-Supercritical carbon dioxide inlet, 2-Slurry inlet, 3-Vertical tank, 4-Guide cylinder, 5-Helical guide vane, 6-Enhanced mixing element, 7-Mixed mixture outlet, 8-Supercritical carbon dioxide outlet, 9-Supercritical carbon dioxide inlet, 10-Dispersion chamber, 11-Supercritical carbon dioxide inlet, 12-Receiving plate, 13-Dispersion hole. Detailed Implementation

[0029] The invention will now be further described with reference to the accompanying drawings.

[0030] Figure 1 A schematic diagram of the mixing device of the present invention is provided. For example... Figure 1 As shown, the supercritical carbon dioxide catalytic cracking slurry mixing device of the present invention includes a vertical tank 3 and a supercritical carbon dioxide inlet 1, a slurry inlet 2, a guide tube 4, a spiral guide vane 5, a strengthening mixing element 6, a supercritical carbon dioxide outlet 8, and a mixture outlet 7 arranged from top to bottom along the vertical tank 3.

[0031] The vertical tank 3 is a cylindrical body. The guide tube 4 is located inside the vertical tank 3. The guide tube 4 consists of two parts: the upper part is a positive cone with a smaller upper end and a larger lower end, and the lower part is an inverted cone with a larger upper end and a smaller lower end. The lower end of the positive cone is also the upper end of the inverted cone. The oil slurry inlet 2 is located on the top end cap of the vertical tank 3 and is coaxially arranged with the vertical tank 3 and the guide tube 4. An annular space is formed between the outer wall of the guide tube 4 and the inner wall of the vertical tank 3. The radial width of the annular space gradually increases from top to bottom. A spiral guide vane 5 is arranged around the guide tube 4 in the annular space. The pitch of the spiral guide vane 5 gradually decreases from top to bottom. The supercritical carbon dioxide inlet 1 is located at the upper part of the vertical tank 3 and is directly connected to the vertical tank 3. The enhanced mixing element 6 is located below the mixing cylinder 4. The supercritical carbon dioxide outlet 8 is located below the enhanced mixing element 6 and above the mixture outlet 7. The mixture outlet 7 is located at the bottom of the vertical tank 3. The bottom of the vertical tank 3 is conical.

[0032] The spiral guide vane 5 is spiral in shape, and the pitch of the spiral guide vane 5 is 0.05 to 0.2 times the diameter of the vertical tank 3. The spiral guide vane makes the annular space between the inner wall of the vertical tank 3 and the guide tube 4 form a spiral channel.

[0033] The diameter of the large end of the lower inverted cone of the guide tube 4 is 0.5 to 0.9 times the diameter of the vertical tank 3, and the diameter of the small end of the lower inverted cone is 0.2 to 0.8 times the diameter of the large end.

[0034] Figure 1 The working process of the mixing device shown is as follows: supercritical carbon dioxide enters the vertical tank 3 directly through the supercritical carbon dioxide inlet 1 located at the top of the vertical tank, and mixes with the oil slurry entering the vertical tank 3 through the oil slurry inlet 2 in the annular space along the spiral guide vane 5. After further mixing by the enhanced mixing element 6, the mixture is discharged from the mixture outlet 7 at the bottom of the vertical tank, and the undissolved supercritical carbon dioxide is discharged through the supercritical carbon dioxide outlet 8.

[0035] Figure 2 This is another schematic diagram of the mixing device of the present invention. As shown in the figure, the device is provided with two supercritical carbon dioxide inlets, namely supercritical carbon dioxide inlet 9 and supercritical carbon dioxide inlet 11. The lower part of the guide tube 4 is a cylindrical tube, and the top of the positive cone tube 4 is directly machined into a platform-shaped receiving plate 12.

[0036] A dispersion chamber 10 is provided between the outer side of the spiral guide vane 5 and the inner wall of the vertical tank 3. A supercritical carbon dioxide inlet 9 is located on the outer wall of the dispersion chamber 10 and communicates with the dispersion chamber 10. A dispersion hole 13 is provided on the inner wall of the dispersion chamber 10 (see...). Figure 3Supercritical carbon dioxide enters the annular space through the dispersion hole 13; simultaneously, the supercritical carbon dioxide inlet 11 extends into the guide tube 4 and communicates with it. The lower wall of the guide tube 4 is provided with injection holes along the circumferential direction (not shown in the figure, but can be referenced). Figure 3 Supercritical carbon dioxide enters the annular space through the injection hole.

[0037] The axial height of the dispersion chamber 10 is 0.5 to 0.9 times the height of the lower cylinder of the guide tube 4, and the radial width of the dispersion chamber 10 is 0.05 to 0.3 times the diameter of the vertical tank 3.

[0038] like Figure 3 As shown, the dispersion holes 13 are circular holes, and are distributed spirally along the spiral direction of the spiral guide vane, with the openings facing the spiral direction of the guide vane. The openings of the injection holes on the lower wall of the guide tube can be referenced. Figure 3 .

[0039] Figure 2 The working process of the mixing device shown is as follows: its working process and Figure 1 The apparatus shown is basically the same, except that the supercritical carbon dioxide enters the mixing device in two ways. One way enters the dispersion chamber 10 through the supercritical carbon dioxide inlet 9, and then enters the annular space through the dispersion hole 13 to mix with the oil slurry; the other way enters the mixing cylinder 4 through the supercritical carbon dioxide inlet 11, and then enters the annular space through the injection hole (not shown in the figure) to mix with the oil slurry.

Claims

1. A supercritical carbon dioxide catalytic cracking slurry mixing device, characterized in that: It includes a vertical tank and, from top to bottom, a supercritical carbon dioxide inlet, an oil slurry inlet, a guide tube, a spiral guide vane, a supercritical carbon dioxide outlet, and a mixture outlet. The vertical tank is generally cylindrical. The guide tube is located inside the vertical tank and is a circular hollow cylinder composed of two parts: an upper part is a positive cone with a smaller upper end and a larger lower end, and a lower part is an inverted cone with a larger upper end and a smaller lower end. The lower end of the positive cone is also the upper end of the lower cavity. The oil slurry inlet is located on the top end cap of the vertical tank and is coaxial with the vertical tank and the guide tube. The supercritical carbon dioxide inlet is located in the upper part of the vertical tank; an annular space is formed between the outer wall of the guide tube and the inner wall of the vertical tank, and a spiral guide vane is arranged around the guide tube in the annular space; the supercritical carbon dioxide outlet is located in the lower part of the vertical tank and above the mixture outlet, and the mixture outlet is located at the bottom of the vertical tank; the large end diameter of the inverted cone is 0.5 to 0.9 times the diameter of the vertical tank, and the small end diameter of the inverted cone is 0.2 to 0.8 times the large end diameter; the pitch of the spiral guide vane is 0.05 to 0.2 times the diameter of the vertical tank.

2. The mixing device according to claim 1, characterized in that: A dispersion chamber is provided between the outer side of the spiral guide vane and the inner wall of the vertical tank. The dispersion chamber is an annular cavity with its upper and lower sides closed. Its outer side wall is the cylindrical wall of the vertical tank. The supercritical carbon dioxide inlet is located on the outer side wall of the dispersion chamber and communicates with the dispersion chamber. A dispersion hole is provided on the inner side wall of the dispersion chamber.

3. The mixing device according to claim 1, characterized in that: The supercritical carbon dioxide inlet extends into the guide tube and is connected to the guide tube. The lower part of the guide tube wall is provided with injection holes along the circumference, and the supercritical carbon dioxide enters the annular space through the injection holes.

4. The mixing device according to claim 2, characterized in that: The guide tube is connected to another supercritical carbon dioxide inlet that extends from the outside of the vertical tank into the guide tube, and injection holes are provided circumferentially on the lower part of the tube wall.

5. The mixing device according to claim 2, characterized in that: The axial height of the dispersion chamber is 0.5 to 0.9 times the height of the lower part of the guide tube, and the radial width of the dispersion chamber is 0.05 to 0.3 times the diameter of the vertical tank.

6. The mixing apparatus according to claim 2, characterized in that: The dispersion holes on the inner wall of the dispersion chamber are distributed in a spiral shape along the spiral direction of the spiral guide vane and are located above the spiral guide vane.

7. The mixing apparatus according to claim 3, characterized in that: The injection holes on the lower part of the guide tube are spirally distributed along the spiral direction of the spiral guide vane and are located above the spiral guide vane.

8. The mixing apparatus according to any one of claims 1 to 7, characterized in that: A receiving plate is installed at the top of the positive cone-shaped guide tube.

9. The mixing apparatus according to any one of claims 1 to 7, characterized in that: The spiral guide vane is spiral-shaped, and the pitch of the spiral guide vane gradually decreases from top to bottom.

10. The mixing apparatus according to any one of claims 1 to 7, characterized in that: An enhanced mixing element is installed below the guide tube and before the supercritical carbon dioxide outlet.

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