Spiral-flow type riser reactor

Abstract

The invention discloses a spiral-flow type riser reactor with an annular space structure. The reactor sequentially comprises a feeding section, a reaction section and a reaction stopping section from bottom to top, and the three sections respectively adopt a concentric cylindrical barrel, a concentric conical barrel and a hollow straight barrel. Raw material and catalyst feeding pipes are both positioned at the feeding section and are tangent to the outer cylinder body according to the same rotating direction, and rotational flow is generated in an annular gap between the inner cylinder and the outer cylinder. The catalytic cracking device is mainly used for preparing low-carbon olefin by taking heavy oil, wax oil, low-carbon alkane gas and the like as raw materials. According to the spiral-flow type riser reactor disclosed by the invention, raw materials and a catalyst can be uniformly mixed, and backmixing is basically eliminated; and a relatively large catalyst-oil ratio and strict reaction time can be adopted, so that the process conditions required for producing low-carbon olefins by catalytic cracking can be met, and compared with the conventional hollow cyclone reactor, the hollow cyclone reactor has obvious advantages.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalytic cracking and catalytic cracking technology, and particularly relates to a cyclone riser for catalytic cracking of heavy oil, wax oil, gaseous alkane and the like to prepare low-carbon olefins. BACKGROUND

[0002] Low-carbon olefins (ethylene, propylene and the like) are basic organic synthesis raw materials. At present, the methods for preparing low-carbon olefins mainly include steam thermal cracking of light raw materials (naphtha, gasoline) and catalytic cracking of heavy hydrocarbon oil (heavy oil, wax oil, diesel oil). With the increasing shortage of light raw materials, catalytic cracking technology has attracted extensive attention from researchers. The riser reactor is an important equipment in a catalytic cracking device for producing low-carbon olefins. The cracking reaction of oil gas under the action of catalyst mainly occurs in the cavity of the riser reactor, and therefore a high requirement is put forward for the mixing and contacting effect of oil gas and catalyst.

[0003] In the conventional riser reactor, the raw material and the catalyst are contacted in parallel, and the two are rapidly reacted after contacting. The axial catalyst concentration distribution is uneven, the mixing effect is poor, and back mixing phenomenon easily occurs, which causes serious coking. In actual production, there are also disadvantages such as low solid content, difficult control of residence time and the like, which are not conducive to the generation of target products. Therefore, it is particularly important to develop a riser reactor with a new structure.

[0004] Patent CN 101850226A uses a variable-diameter riser with a bottom expanding-diameter and an upper shrinking-diameter, which increases the reaction section catalyst-oil ratio, shortens the upper material residence time, and can effectively control the target reaction of different properties of materials, obtaining higher low-carbon olefin yield under relatively mild operating conditions. Patent CN 112708447A discloses a riser reactor with reduced side wall zone back mixing, which includes a pre-lifting section and a fast fluidized bed section arranged in turn from bottom to top along the vertical direction, a connecting section is arranged between the two sections, and annular air supplementing components are arranged inside the two sections, and a guide plate is arranged at the side wall to accelerate the mixing of materials, effectively reduce the back mixing of catalyst particles in the side wall area, and blow off the catalyst particles enriched in this area, which can effectively inhibit the side reaction. Patent CN 115895710A discloses a double-riser reactor, which contacts and reacts the first reaction oil gas obtained by the first riser reactor and the second spent catalyst obtained by the second riser reactor in a countercurrent reactor. This method can promote the further conversion of heavy oil catalytic cracking intermediates to low-carbon olefins, and improve the yield and selectivity of low-carbon olefins. Patent CN 116769511 A relates to a high-low parallel countercurrent multi-stage reactor, which can be combined with a riser and a downward fluidized bed reactor. This device can reduce gas-solid back mixing and control residence time, ensure the flow stability of the catalyst during the reaction process, solve the problem of uneven feeding of the multi-stage reactor, and can perform high-severity catalytic cracking / cracking operation. The above reactors are beneficial to the synthesis of target products, but further improvement is needed in improving the catalyst-oil contact efficiency.

[0005] The contact effect between oil / gas and catalyst depends on their mixing method. Currently, the main fluid mixing methods include mechanical stirring, jet mixing, collision mixing, and static mixing. Swirl mixing is a highly efficient and energy-saving method. Applying swirl mixing to catalytic cracking reactors can effectively improve the mixing and contact effect between feedstock and catalyst. Existing research mainly focuses on installing components inside the riser reactor and modifying or combining risers. For example, patent CN117384662 A installs a propeller-shaped swirl distribution plate at the bottom of the riser reactor, causing the fluidizing medium to rotate through the swirl distribution plate, thereby driving the feedstock oil and catalyst to a swirling fluidized state, enhancing gas-solid contact, and effectively improving the conversion rate and selectivity of catalytic cracking to produce low-carbon olefins. Patent CN 103571518 A discloses a process combining a riser and a swirl reactor. The top of the riser is connected to the feed inlet of the swirl reactor via a straight or inclined pipe. Catalytic dry gas carrying the catalyst rises from the bottom of the riser, while the feedstock oil enters from the top of the riser, allowing the catalytic cracking reaction to mainly take place in the swirl reactor. This process reduces backmixing between the oil and the agent, shortens the material residence time, and is beneficial to improving production efficiency. Patent CN 103409159 A mentions a direct-flow short-contact swirl reactor, specifically involving the installation of guide vanes inside the reactor and a rectifier cone coaxial with the cylinder at the location of the guide vanes. This swirl reactor improves the contact efficiency between the agent and the oil while shortening the reaction time. However, when applying swirl mixing to catalytic cracking reactors, research on maintaining the stability of the swirl and reducing modification costs is still lacking, and further improvements to structural characteristics are needed.

[0006] In summary, it is crucial to develop riser reactors that combine the advantages of rapid and uniform material mixing, continuous and stable swirl, minimal backmixing, a large agent-to-oil ratio, and suitable residence time, thereby promoting the widespread application of riser reactors in the field of catalytic cracking for the preparation of low-carbon olefins. Summary of the Invention

[0007] The purpose of this invention is to provide an advanced cyclone riser catalytic cracking reactor to solve the engineering problems encountered in the synthesis of low-carbon olefins. The technical solution is as follows:

[0008] A cyclone riser reactor, wherein the main body of the riser reactor consists of three sections, including a feed section, a main reaction section and a reaction termination section connected sequentially from bottom to top;

[0009] The feed section is located at the bottom of the reactor and is a cylindrical annular tube consisting of an outer cylinder and an inner cylinder; the main reaction section is a tapered annular tube with a gradually decreasing diameter consisting of an outer tube and an inner tube, located in the middle of the reactor; the reaction termination section has the smallest diameter, is a straight tube, and is located at the top of the reactor.

[0010] The cyclone riser reactor further comprises a plurality of feed pipes; the feed pipes are located in the feed section and connected with the outer cylinder in tangential mode with the same turning direction.

[0011] The feed pipes comprise raw material feed pipes and catalyst feed pipes; the catalyst feed pipes are connected with the raw material feed pipes in tangential mode and then enter the feed section.

[0012] The cylindrical annular pipe is composed of concentrically arranged outer cylinder and inner cylinder; wherein the diameter ratio of the outer cylinder to the inner cylinder is 2:1-5:4 and the height ratio is 2:1-1:1.

[0013] The main reaction section is composed of concentrically arranged outer pipe and inner pipe; wherein the contraction angle of the outer pipe is 2°-6°, preferably 4°.

[0014] The bottom diameter of the outer pipe is equal to the diameter of the outer cylinder and the bottom diameter of the inner pipe is equal to the diameter of the inner cylinder.

[0015] The inner pipe is a closed hollow conical structure with the top diameter of 0.

[0016] The straight pipe of the reaction termination section has the same diameter as the top diameter of the outer pipe.

[0017] The raw material is liquid material and / or gaseous material; the liquid material is selected from heavy oil, wax oil and gas oil and the gaseous material is selected from ethane and propane.

[0018] The catalyst feed pipes are connected with the raw material feed pipes in tangential mode and then enter the riser through the raw material feed pipes. Tangential feeding can promote the rapid diffusion of catalyst and accelerate the uniform mixing of materials, effectively shortening the gas-solid residence time. Whether the auxiliary feed pipe is installed or not depends on the situation, as long as the cyclone intensity is ensured. If the auxiliary feed pipe is installed, it should also be arranged in the feed section to ensure the short contact reaction effect and facilitate the catalytic cracking reaction.

[0019] The annular gap between the outer pipe and the inner pipe of the main reaction section is small, which can make the reaction materials form rapid cyclone. The existence of the inner pipe solves the problem that the traditional cyclone equipment only relies on the inertial motion of fluid to generate cyclone at the inlet of the equipment, but the cyclone disappears soon after, ensuring the orderliness and stability of the cyclone and reducing the degree of back mixing. In addition, due to the small annular gap space, the basic requirement of completing the catalytic cracking reaction in a short contact time can be met; due to the large cyclone intensity, the oil can carry more catalyst to provide the required catalytic active center to ensure a large catalyst / oil ratio; the conical structure is also conducive to accelerating the flow of reaction products to the outlet, so that they have a suitable residence time, reduce the continuous conversion reaction of low-carbon olefins and improve the selectivity of low-carbon olefins.

[0020] Compared with existing patents, the significant feature of the riser reactor proposed in this invention is that both the feed section and the main reaction section of the reactor are jacketed structures, while currently disclosed patents all use hollow structures. Because the jacket gap is very thin, the inner cylinder (inner tube) has a large diameter. Therefore, the fluid can be subjected to a strong centrifugal force (centrifugal force is proportional to the radius at a constant angular velocity), thereby generating strong swirling flow. Swirling flow keeps the fluid in a plug flow state, suppressing backmixing. On the other hand, because the fluid is confined within the jacket, the flow velocity is greatly increased compared to when it is dispersed throughout the entire cross-section. The higher the flow velocity, the higher the degree of turbulence, which is more conducive to mixing. Therefore, compared with the prior art, the annular gap riser reactor of this invention has the advantages of high mixing degree and controllable reaction time. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the cyclone riser reactor of the embodiment. Wherein, Figure 1 (a) Figure 1 (b) represent three-dimensional and two-dimensional structures, respectively.

[0022] Figure 2 This is a flow chart of an industrial catalytic cracking unit.

[0023] Figure 3 This is a schematic diagram of a comparative swirl-type riser structure. Among them, Figure 3 (a) Figure 3 (b) represent three-dimensional and two-dimensional structures, respectively.

[0024] Figure 4 This is a diagram showing the trajectory of catalyst particles. Figure 4 (a) is an embodiment of the present invention. Figure 4 (b) is a comparative example.

[0025] Figure 5 These are nine groups of particle residence time distribution diagrams. Among them, Figure 5 (a) is an embodiment of the present invention. Figure 5 (b) is a comparative example.

[0026] Figure 6 These are nine sets of particle velocity distribution diagrams. Among them, Figure 6 (a) is an embodiment of the present invention. Figure 6 (b) is a comparative example.

[0027] Symbol explanation:

[0028] 1 - inlet seal plate; 2 - feed pipe 1 of raw material; 3 - feed pipe 2 of raw material; 4 - outer cylinder wall of reactor; 5 - inner cylinder; 6 - inlet pipe of reaction director; 7 - straight cylinder wall; 8 - settler; 9 - cyclone separator; 10 - gas collecting chamber; 11 - product outlet pipe; 12 - stripping device; 13 - inlet pipe of fuel oil; 14 - valve to regenerator; 15 - flue gas outlet pipe; 16 - regenerator cyclone separator; 17 - regenerator; 18 - regenerating medium; 19 - valve of regenerated catalyst; 20 - feed pipe of regenerated catalyst; 21 - inner cylinder of feed section. DETAILED DESCRIPTION

[0029] The present application is implemented in the following way:

[0030] As shown in Figures 1-2 , the raw material enters the cyclone riser reactor 4 through the feed pipes 2 and 3, and is mixed with the catalyst injected from the feed pipe 20, and then rotates, mixes and flows upward in a fast cyclone manner around the inner cylinder 5. After reaching the conical annular section, it is contacted with the reaction director injected at the tail 6 of the section, and the reaction is terminated. The material leaves the outlet of the straight cylinder section 7 and enters the separation device such as the cyclone separator 9 for gas-solid separation. The separated gas product is discharged from the product outlet pipe 11 through the gas collecting chamber 10 and enters the subsequent product separation equipment. The separated catalyst to be regenerated passes through the valve 14 into the regenerator 17 after further deposition of coke, and the regenerated catalyst is obtained after removal of flue gas and is transported to the cyclone riser reactor for recycling.

[0031] The following explains the difference between the material flow characteristics of the present application and the comparative example due to the structural difference.

[0032] For the cyclone riser reactor involved in the present application, the comparative structure differs from the structure of the present application in whether the inner cylinder is included, as shown in Figure 1 and Figure 3 , and other aspects remain the same. The inner cylinder of the comparative structure only exists in the feed section, and the conical section is hollow, as shown in structure 4 in Figure 3 .

[0033] Simulation tests were carried out in the two different structures of the cyclone riser reactor: first, the trajectory of the material was tracked, and the results showed that the material in the two structures of the cyclone riser reactor moved upward in a spiral trajectory, as shown in Figure 4 ; then 9 kinds of particles were used for residence time distribution and velocity distribution simulation, as shown in Figure 5 and Figure 6 . For a riser with a total height of 22 meters (2 meters of feed section, 10 meters of main reaction section, and 10 meters of reaction termination section), the difference in residence time of the 9 groups of particles in the embodiment of the present application is at most 0.1 s, while the difference in the comparative example is 1.5 s Figure 5). The velocity distribution of the example is approximately coincident, while the comparative structure has a larger difference Figure 6 ). It shows that the cyclone riser reactor adopted in the application has uniform material distribution and small back mixing, and is close to a plug flow reactor.

[0034] The features of the application are described below in connection with specific examples.

[0035] In the examples and comparative examples, the preferred reaction temperature is 550-650℃, the reaction pressure is 0.3-1 MPa, the agent-oil ratio is 12-13:1, and the residence time is 4-10 s. The raw material can be light raw oil or poor quality heavy oil. The raw material used is hydrogenated light cycle oil, and its properties are shown in Table 1. The catalyst selected is a 40wt% slurry with a solid content of 40wt%, which is prepared by spraying and drying a slurry formed from 20wt% modified Y-type molecular sieve, 10wt% silica binder, 70wt% kaolin carrier and water, and is referred to as SLA catalyst, and its properties are shown in Table 2.

[0036] Table 1 Properties of raw oil

[0037]

[0038] Table 2 Properties of catalyst

[0039]

[0040] Example 1

[0041] In Figure 1 The raw material and catalyst are respectively added in a tangential manner in the feed pipe of the cyclone riser reactor shown in the figure, the preheating temperature of the raw material is 200℃, the raw oil and catalyst are rapidly and uniformly mixed, and the catalytic cracking reaction is carried out at 0.2 MPa and a temperature of 520℃. The reaction is terminated in time after the reaction director added at the tail of the conical annular section is contacted, and then the material is discharged from the outlet of the straight cylinder section, enters the cyclone separator, and is subjected to gas-solid separation. The product oil gas separated is led out by the gas collection chamber, product outlet pipe and leading device, and the spent catalyst separated is stripped by the stripping device, and then contacted with fuel oil to further deposit coke. After that, it passes through the valve into the regenerator, and the regenerated catalyst is obtained after regeneration and recycled. The relevant data are shown in Table 3.

[0042] Example 2

[0043] The preheated raw material enters the reactor through the feed pipe 2, 3, the preheating temperature is 200 DEG C, is mixed with the regenerated catalyst from the regenerator, and then the material is reacted in the annular gap of the reactor in the cyclone mode, the reaction condition is 0.4 MPa, the outlet temperature is 580 DEG C, the reaction product is contacted with the reaction directing agent added at the tail of the conical annular gap section, and the reaction is quenched in time, the obtained catalyst with coke is separated from the reaction oil gas through the straight cylinder section, and the oil gas product is introduced through the gas collecting chamber and the product outlet pipe, and the spent catalyst is stripped through the stripping device, and then contacted with fuel oil to further deposit coke, and then enters the regenerator through the valve, and the regenerated catalyst is recycled after regeneration, and the related data are listed in Table 3.

[0044] Comparative examples 1 and 2

[0045] The raw materials and catalysts shown in Table 1 and Table 2 are used in the riser reactor shown in Table 3 to carry out the reaction according to the conditions of examples 1 and 2, and the related data are listed in Table 3. Figure 3 The riser reactor shown in Table 3 is used to carry out the reaction according to the conditions of examples 1 and 2, and the related data are listed in Table 3.

[0046] Comparison of catalytic cracking effects of two types of riser reactors

[0047]

[0048] The test results show that the cyclone riser reactor of the application has better mixing effect than the conventional cyclone riser reactor, the residence time control is more accurate, the solid content in the reactor is greatly improved, the flow state is close to plug flow, the back mixing is small, and the reaction conditions for preparing low-carbon olefins by catalytic cracking are met, and the raw oil conversion rate and the low-carbon olefin yield are improved.

[0049] The orientation words (up, down, etc.) mentioned in the application only represent the position shown in the drawings, and play a role in facilitating description and understanding, and can be adjusted according to actual conditions.

[0050] Finally, it should be pointed out that: the above only describes the preferred embodiments of the application, and is not used to limit the application, although the application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application, should be included in the protection scope of the application.

Claims

1. A cyclonic riser reactor characterized by, The main body part of the riser reactor is composed of three sections, including a feeding section, a main reaction section and a reaction termination section connected in sequence from bottom to top; The feeding section is located at the bottom of the reactor and is a cylindrical annular gap pipe including an outer cylinder and an inner cylinder; the main reaction section is a tapered annular gap pipe including an outer pipe and an inner pipe and is located in the middle of the reactor; the reaction termination section is a straight pipe with the smallest diameter and is located at the top of the reactor.

2. The cyclonic lift reactor according to claim 1, characterized in that Further comprising a plurality of feeding pipes; the feeding pipes are located in the feeding section and are connected with the outer cylinder in a tangential manner.

3. The cyclonic lift reactor according to claim 2, characterized in that The feeding pipes include raw material feeding pipes and catalyst feeding pipes; the catalyst feeding pipes enter the feeding section after tangential convergence with the raw material feeding pipes.

4. The cyclonic lift reactor of claim 1, wherein, The cylindrical annular gap pipe is composed of concentrically arranged outer and inner cylinders; the ratio of the diameters of the outer and inner cylinders is 2:1-5:4, and the ratio of the heights is 2:1-1:

1.

5. The cyclonic lift reactor of claim 1, wherein, The main reaction section is composed of concentrically arranged outer and inner pipes; the contraction angle of the outer pipe is 2°-6°.

6. The cyclonic lift reactor according to any of claims 1 or 4 or 5, characterized in that The bottom diameter of the outer pipe is equal to the diameter of the outer cylinder, and the bottom diameter of the inner pipe is equal to the diameter of the inner cylinder.

7. The cyclonic lift reactor according to claim 5, characterized in that The contraction angle of the outer pipe is 4°.

8. The cyclonic lift reactor according to claim 6, characterized in that The inner pipe is a closed hollow conical structure with a top diameter of 0.

9. The cyclonic lift reactor according to claim 1, characterized in that The diameter of the straight pipe of the reaction termination section is the same as the top diameter of the outer pipe.

10. The cyclonic lift reactor according to claim 3, characterized in that The raw material is a liquid material and / or a gaseous material; the liquid material is selected from heavy oil, wax oil and gas oil, and the gaseous material is selected from ethane and propane.

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