Spiral columnar catalyst particle and application thereof
By designing spiral columnar catalyst particles, the problem of closed fluid channels when catalyst particles are axially arranged side by side is solved, achieving more uniform fluid distribution and lower bed pressure drop, and improving the efficiency and life of the catalyst.
Patent Information
- Application Number
- CN202510763448.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-09
- Publication Date
- 2025-10-10
AI Technical Summary
Existing catalyst particles tend to block fluid channels when arranged axially side by side, resulting in uneven fluid distribution in the bed, low catalyst utilization, high bed pressure drop and the appearance of hot spots.
The spiral columnar catalyst particles are designed by setting a specific geometric shape on the radial section and applying a twist angle along the axial direction to form a spiral outer surface structure, avoiding closed fluid channels between particles and improving the bed porosity and fluid distribution uniformity.
It significantly improves the uniformity of bed fluid distribution, increases catalyst utilization and life, reduces bed pressure drop, enhances unit operation safety and reduces costs.
Smart Images
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a kind of catalyst or catalyst carrier used in petrochemical field etc., it is suitable to be used as catalyst or catalyst carrier filler in fixed bed, suspended bed, bubble bed etc. BACKGROUND
[0002] For different industrial production processes, catalyst usually needs to be processed into suitable shape. Proper appearance shape helps to improve its performance parameters, such as specific surface area, bed bulk density, bed porosity, bed pressure drop, interphase mass transfer efficiency, reaction performance, etc.
[0003] Currently, the main appearance of catalyst particles includes spherical, tooth spherical, porous spherical, cylindrical, clover shape, four-leaf clover shape, Raschig ring shape, wheel shape, gear shape, etc.
[0004] For commonly used catalyst in industry, especially clover-shaped catalyst particles, when multiple particles are arranged side by side along the axial direction, the "clover leaves" between each particle are mutually embedded, thereby closing the channel perpendicular to the particle arrangement direction. This will result in the fluid being unable to pass through, thereby causing uneven fluid distribution in the bed, low catalyst utilization, hot spots in the bed, and high bed pressure drop.
[0005] Therefore, especially for the reactor form of uneven fluid distribution in the bed and high pressure drop, an optimized catalyst particle appearance structure is needed to improve the local fluid flow process in the packed bed, increase the catalyst utilization and service life, and reduce the bed pressure drop. SUMMARY
[0006] The purpose of the present application is to provide a spiral cylindrical catalyst particle, and the particle appearance structure can effectively avoid the situation that the cylindrical catalyst particle closes the fluid channel when arranged side by side along the axial direction, thereby improving the local fluid flow process in the packed bed, improving the catalyst utilization and service life, and reducing the operating pressure of the device.
[0007] The spiral cylindrical catalyst particle provided by the present application has a radial cross section in the shape of a clover, a four-leaf clover, a plum blossom, or any geometric shape; the catalyst particle is twisted by a non-zero angle around its axial direction, forming a spiral outer surface structure.
[0008] Preferably, the radial cross section is selected from a geometric shape group comprising a clover, a four-leaf clover, and a plum blossom, and comprises at least one of the following characteristics:
[0009] A leaf-shaped profile composed of multiple intersecting circles; a hollow hole is provided in the center area of the cross section.
[0010] The spiral shape of the spiral columnar catalyst particle can effectively avoid the situation that multiple particles are arranged side by side along the length direction of the particle, thereby having the characteristics of high bed porosity and large number of micro-pore flow channels.
[0011] The spiral columnar catalyst particle can effectively improve the fluid distribution uniformity in the bed, improve the catalyst utilization rate and reduce the probability of hot spot temperature runaway, and has excellent performance in reducing the bed pressure drop.
[0012] Preferably, the twist angle is 5°-360° / mm axial length, preferably in the range of 18°-72° / mm axial length. With the increase of the twist degree per unit axial length of the particle, the bed porosity obtained by random stacking of particles with the same mass is slightly increased, and the bed pressure drop of the packed bed under the same gas / liquid flow rate operating conditions is significantly reduced. It should be noted that with the increase of the twist degree per unit axial length of the particle, the change in the bed porosity and the fluid passing through the bed pressure drop caused by the newly added twist angle is reduced. For example, compared to the influence of the particle with a twist angle of 0° / mm axial length on the bed porosity and pressure drop, the influence of the particle with a twist angle of 60° / mm axial length on the bed porosity and pressure drop is reduced, and the influence of the particle with a twist angle of 120° / mm axial length on the bed porosity and pressure drop is further reduced.
[0013] Preferably, the axial length L of the catalyst particle is 2 to 30 times the equivalent diameter D of the radial cross section, wherein the equivalent diameter of the radial cross section refers to the diameter of a circle with the same area as the radial cross section. Under the condition that the equivalent diameter D of the radial cross section of the particle is fixed, with the increase of the axial length of the particle, the bed porosity obtained by random stacking of particles with the same mass is increased, and the bed pressure drop of the packed bed under the same gas / liquid flow rate operating conditions is reduced.
[0014] Preferably, when the radial cross section is clover-shaped, it has the following characteristics:
[0015] The three main circles are symmetrically distributed at an angle of 120°, and the center distance of the circles is 0.5-1.5 times the radius of the main circle.
[0016] The secondary circle structure tangent to the main circle has a diameter of 0.2-0.8 times the diameter of the main circle.
[0017] Preferably, the carrier material of the catalyst particle is selected from at least one inorganic oxide of alumina, zirconia, titania, ceria, silica, and zinc oxide, and the active phase is composed of Fe, Ni, Co, Mo, Cu, Pt, Pd, Rh and / or mixtures thereof.
[0018] Preferably, the spiral outer surface of the catalyst particle is formed by a mold extrusion molding process or a 3D printing molding process.
[0019] Based on the catalyst particles, the present invention further provides a fixed bed reactor filled with the spiral columnar catalyst particles, and the spatial positions and postures of the particles are randomly distributed in the bed.
[0020] The spiral columnar catalyst particles provided by the present invention can be used for gas phase / solid phase, liquid phase / solid phase, and gas phase / liquid phase / solid phase catalytic reactions, such as: residual oil hydrogenation process, diesel hydrorefining, flue gas desulfurization, ammonia synthesis process, methanol synthesis process, etc.
[0021] The present invention has the following advantages due to the adoption of the above technical solution:
[0022] 1. It avoids the problem of interlocking of columnar particles when they are arranged side by side along the axial direction. More tiny channels can exist perpendicular to the axial direction of the particles, and these channels can be used for fluid to pass through.
[0023] 2. Improve the porosity of the bed. The spiral columnar catalyst particles are separated from each other by a spiral outer structure. Compared with the untwisted columnar particles, they have more spiral pore structures, making the bed stacking looser.
[0024] 3. Improve the uniformity of fluid distribution and movement speed in the bed. Under a certain flow rate, the fluid can flow through and disperse in more pore structures, which can effectively improve the local flow phenomenon of the bed.
[0025] 4. Improve catalyst utilization and life. The fluid can wet more particle surfaces to improve the utilization efficiency of the active centers of the catalyst particles. In addition, more porous structures can avoid hot spots and high temperatures in local flow dead zones, thereby extending the service life of the catalyst.
[0026] 5. Reduce bed pressure drop. Under certain fluid flow conditions, there are more porous structures in the bed composed of spiral columnar catalyst particles, so the flow channels are increased and the actual flow rate of the fluid is reduced, thereby effectively reducing the bed pressure drop, improving the operating safety of the device and reducing the cost of the device. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 Schematic diagram of the spiral cloverleaf catalyst particles of the present invention.
[0028] Figure 2 It is a schematic diagram comparing the appearance structure of the spiral cloverleaf catalyst particles of the present invention and the conventional cloverleaf catalyst particles.
[0029] Figure 3 This is a comparative schematic diagram of a fixed bed of cloverleaf catalyst particles with different degrees of twisting.
[0030] Figure 4It is the change of bed porosity and pore equivalent hydraulic diameter with the degree of particle torsion.
[0031] Figure 5 is the variation of bed pressure drop with particle torsion degree at different Reynolds numbers.
[0032] Figure 6 In the figure, Figure a shows the change of radial porosity distribution of the bed with the degree of particle torsion, and Figure b shows the comparison of radial porosity distribution of fixed beds with different degrees of particle torsion (with untwisted particles as the unit value).
[0033] Figure 7 In the figure, Figure a shows the change of radial fluid velocity distribution in the bed with the degree of particle torsion, and Figure b shows the comparison of radial fluid velocity distribution in fixed beds with different degrees of particle torsion (with untwisted particles as the unit value).
[0034] Figure 8 It is a comparison of the radial fluid flow distribution in fixed beds with different degrees of particle twisting (with untwisted particles as the unit value). DETAILED DESCRIPTION
[0035] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.
[0036] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.
[0037] To improve localized flow in a fixed bed, enhance fluid distribution uniformity, and reduce bed pressure drop, the present invention provides a catalyst configuration in which columnar catalyst particles are twisted axially to form a spiral shape. The present invention is described in detail below through several embodiments, with reference to the accompanying drawings.
[0038] Example 1: Spiral Clover Catalyst Particles
[0039] like Figure 1 As shown, its radial cross section contains three circles with a diameter of 1 mm, and the center of each circle is 0.6 mm away from the geometric center, and the centers of any two of the three circles form an angle of 120°; along the direction of the intersection of the three circles, 0.8 mm away from the geometric center, there are three small circles with a diameter of 0.4422 mm tangent to the three large circles. The arc segments of the three small circles tangent to the large circles and the arc segments of the three large circles away from the geometric center are taken as the clover contour. The above clover contour is stretched for 5 mm in a direction perpendicular to the outer contour, and then twisted at 36° / mm with the axial direction of the columnar clover particle as the axis to obtain the spiral clover catalyst particle shown in the figure (wherein the catalyst carrier is γ-Al2O3 and the active center is Ru).
[0040] The ratio of the axial length L to the radial cross-sectional equivalent diameter D of the catalyst particles prepared in this example is 2.79:1.
[0041] Comparative Example 2
[0042] Without changing the cross-sectional shape and area, axial length, and surface area of the particles, only the particles are twisted, such as Figure 2 shown.
[0043] The following five groups of numerical simulations are compared: Figure 3 As shown:
[0044] Each bed contained 101 particles, and the initial release position and spatial orientation of each particle were consistent. The parameters such as particle-particle and particle-wall collision and friction were also consistent, resulting in a fixed bed as above (the diameter of the cylindrical bed was 14 mm, and the bed height varied slightly according to the actual stacking situation, with approximately 5 mm empty columns left above and below the particles).
[0045] By changing the initial release position and posture of the particles, keeping the collision and other parameters the same, repeating 4 times, another 4 groups of fixed beds are obtained, and there are 5 fixed beds for particles with each torsion angle.
[0046] The 25 fixed beds mentioned above were simulated under the same parameter settings, and the calculated bed pressure drops were averaged (for example, the values of 5 fixed beds with a twist degree of 0° / mm were averaged). Unless otherwise specified, the other data below were also averaged using the same method.
[0047] The calculated bed porosity and pore equivalent hydraulic diameter (characterizing the looseness of particle packing and the number and size of pores between particles) are as follows: Figure 4 As shown in Table 1:
[0048] Table 1 Average bed porosity and average pore equivalent hydraulic diameter
[0049] 0° / mm 18° / mm 36° / mm 54° / mm 72° / mm Porosity 0.5444 0.5764 0.5939 0.6182 0.6258 Hydraulic diameter / mm 1.5797 1.7981 1.9325 2.1417 2.2131
[0050] The bed pressure drop is calculated at Reynolds numbers of 10, 50, 100, 500, 1000, 5000, and 10000. As the degree of particle twisting increases, the bed pressure drop can be reduced by about 30%. Figure 5 and as shown in Table 2.
[0051] Table 2 Average bed pressure drop (Pa) at different Reynolds numbers
[0052] Re10 Re50 Re100 Re500 Re1000 Re5000 Re10000 0° / mm 2.95 25.47 71.41 981.88 3294.31 63987.12 244208.32 18° / mm 2.39 21.05 59.94 853.82 2903.52 57299.48 219577.71 36° / mm 2.21 19.22 54.42 767.57 2603.11 50821.91 193466.00 54° / mm 1.95 17.16 48.89 696.75 2361.37 46345.63 177590.37 72° / mm 1.95 17.15 48.79 691.15 2336.51 45005.12 171350.59
[0053] Comparing the porosity distribution on the radial section, the porosity in the particle bed is higher after twisting, and this is not only reflected in the side wall position, but also in the middle of the bed. This means that there are more evenly distributed pores on the radial section for fluid to pass through, such as Figure 6 As shown in Table 3.
[0054] Table 3 Average radial porosity distribution of fixed beds with different particle torsion degrees
[0055]
[0056]
[0057] It is precisely because of the more uniform pore distribution mentioned above that the fluid flows more from the middle of the bed, which significantly improves the uneven fluid distribution problem of "high on the side walls and low in the center" (Reynolds number is 1000). Figure 7 and as shown in Table 4.
[0058] Table 4 Average radial fluid velocity distribution (m / s) of fixed beds with different particle torsion degrees
[0059]
[0060]
[0061] The flow distribution on the radial section also supports the conclusion that "twisted particles improve the fluid distribution in the bed" (Reynolds number is 1000). The fluid reduced at the side wall passes more through the middle of the bed, such as Figure 8 As shown in Table 5:
[0062] Table 5 Average radial fluid flow rate distribution (kg / s) of fixed bed with different particle torsion degrees
[0063]
[0064]
[0065]
[0066] Example 2: Spiral Clover Catalyst Particles
[0067] like Figure 1As shown, the radial cross section contains three circles with a diameter of 1 mm, each centered 0.6 mm from the geometric center, with any two of the three circles forming a 120° angle. Three smaller circles with a diameter of 0.4422 mm are tangent to the three larger circles at their intersection, 0.8 mm from the geometric center. The arc segments of the three smaller circles tangent to the larger circles and the arc segments of the three larger circles away from the geometric center are taken as the clover leaf outline. This clover leaf outline is stretched 5 mm perpendicular to the outer contour and then twisted 72° / mm around the axial direction of the cylindrical clover particle to obtain the spiral clover catalyst particle shown.
[0068] The ratio of the axial length L to the radial cross-sectional equivalent diameter D of the catalyst particles prepared in this example is 2.79:1.
[0069] Practice has shown that the fixed bed filled with the spiral catalyst particles (the same carrier and active phase as those used in Example 1) has a bed pressure drop reduced by about 30% compared to the fixed bed filled with untwisted cloverleaf catalyst particles.
[0070] Example 3: Spiral asymmetric cloverleaf catalyst particles
[0071] The radial cross section consists of three circles of different diameters. The coordinates and diameters of the three circles on the two-dimensional plane are (0, 0.1, 0.6), (-0.5196, -0.3, 0.5), and (0.5196, -0.3 0.4), expressed in millimeters. The arcs of the three circles, separated from the geometric center, are used as the asymmetric trefoil profile. This asymmetric trefoil profile is stretched 8 mm perpendicular to the outer contour and then twisted 54° / mm around the axial direction of the cylindrical asymmetric trefoil particle to produce a spiral asymmetric trefoil catalyst particle (with a catalyst carrier composed of γ-Al2O3 and active centers composed of Co-Mo).
[0072] The ratio of the axial length L to the radial cross-section equivalent diameter D of the catalyst particles prepared in this example is 10.13:1.
[0073] Example 4: Spiral Four-Leaf Clover Catalyst Particles
[0074] The radial cross section contains four circles with a diameter of 1 mm, each with a center 0.8 mm from the geometric center, and any two of the four circles' centers form a 90° angle. Another circle with a diameter of 1.4 mm and centered at the geometric center intersects with the four circles. The arc of the five circles away from the geometric center is taken as the four-leaf clover outline. The four-leaf clover outline is stretched 10 mm in a direction perpendicular to the outer contour, and then twisted at 30° / mm with the axial direction of the four-leaf clover particle as the axis to obtain a spiral four-leaf clover catalyst particle (wherein the catalyst carrier is γ-Al2O3 and the active center is Ni-Mo).
[0075] The ratio of the axial length L to the equivalent diameter D of the radial cross-section of the catalyst particle prepared in this example is 9.22:1.
[0076] Example 5, helical plum blossom catalyst particle
[0077] The radial cross-section contains five circles each with a diameter of 1 mm, the center of each circle is 0.9 mm away from the geometric center, and the center of any two of the five circles forms a 72° angle; another circle with a diameter of 1.8 mm and the geometric center as the center intersects the above five circles. The segment circular arc of the above six circles away from the geometric center is taken as the plum blossom profile. The above plum blossom profile is stretched by 10 mm along the direction perpendicular to the profile, and then twisted by 60° / mm along the axial direction of the columnar particle, to obtain a helical plum blossom catalyst particle (the catalyst carrier is γ-Al2O3, and the active center is Ni-W).
[0078] The ratio of the axial length L to the equivalent diameter D of the radial cross-section of the catalyst particle prepared in this example is 8.15:1.
[0079] Example 6, helical plum blossom catalyst particle with holes
[0080] The radial cross-section contains five circles each with a diameter of 1 mm, the center of each circle is 0.9 mm away from the geometric center, and the center of any two of the five circles forms a 72° angle; another circle with a diameter of 1.8 mm and the geometric center as the center intersects the above five circles. The segment circular arc of the above six circles away from the geometric center is taken as the plum blossom profile, and then a circle with a diameter of 1 mm and the geometric center as the center is drawn, and the circle is removed from the plum blossom profile. The above plum blossom profile with holes is stretched by 7 mm along the direction perpendicular to the profile, and then twisted by 18° / mm along the axial direction of the plum blossom particle with holes, to obtain a helical plum blossom catalyst particle with holes (the catalyst carrier is γ-Al2O3, and the active center is Pt-Pd).
[0081] The ratio of the axial length L to the equivalent diameter D of the radial cross-section of the catalyst particle prepared in this example is 6.25:1.
[0082] The helical columnar catalysts in the above examples can be prepared by changing the mold structure. It has been proved that the above helical columnar catalyst particles can significantly reduce the bed pressure drop, effectively improve the local flow phenomenon in the bed, improve the catalyst utilization rate, improve the uniformity of the distribution of fluid and its movement speed in the bed, timely remove heat in the bed to avoid hot spots, and prolong the service life of the catalyst.
Claims
1. A spiral columnar catalyst particle, characterized in that: The radial cross-section of the catalyst particle is in the shape of a clover, a four-leaf clover, a plum blossom or any other geometric shape; a non-zero twist angle is applied to the catalyst particle around its axial direction to form a spiral outer surface structure.
2. The spiral columnar catalyst particles according to claim 1, characterized in that: The radial cross section is selected from a group of geometric shapes including a clover shape, a four-leaf clover shape, and a plum blossom shape, and includes at least one of the following features: A leaf-like profile formed by multiple intersecting circles; with a hollow hole in the center of the cross section.
3. The spiral columnar catalyst particles according to claim 1 or 2, characterized in that: The torsion angle is 5°-360° / mm axial length.
4. The spiral columnar catalyst particle according to any one of claims 1 to 3, characterized in that: The axial length L of the catalyst particle is 2 to 30 times the equivalent diameter D of the radial cross section, wherein the equivalent diameter of the radial cross section refers to the diameter of a circle having the same area as the radial cross section.
5. The spiral columnar catalyst particle according to any one of claims 1 to 4, characterized in that: The support material of the catalyst particles is selected from at least one inorganic oxide of alumina, zirconia, titania, cerium oxide, silicon oxide, and zinc oxide, and the active phase is composed of the following metals: Fe, Ni, Co, Mo, Cu, Pt, Pd, Rh and / or mixtures thereof.
6. The spiral columnar catalyst particle according to any one of claims 1 to 5, characterized in that: The spiral outer surface of the catalyst particles is obtained by die extrusion molding or 3D printing molding process.
7. A fixed bed reactor, characterized in that: The bed is filled with the spiral columnar catalyst particles according to any one of claims 1 to 6, and the spatial positions and postures of the particles are randomly distributed in the bed.
8. Use of the spiral columnar catalyst particles according to any one of claims 1 to 6 or the fixed bed reactor according to claim 7 in gas phase / solid phase, liquid phase / solid phase, or gas phase / liquid phase / solid phase catalytic reactions.