A microdroplet gas-liquid distributor, distribution assembly, and fixed bed hydrogenation reactor

Abstract

The application discloses a micro-droplet gas-liquid distributor, a distribution assembly and a fixed bed hydrogenation reactor, belongs to the field of petroleum chemical industry, and gas phase enters a mixed channel from a gas phase inlet at the top end of the mixed channel to generate negative pressure, then is sucked into liquid phase and is discharged from the bottom end opening of the mixed channel after being mixed with the gas phase, the liquid suction port divides the mixed channel into a buffer adjustment area close to the gas phase inlet and a liquid storage area close to the bottom end opening, the buffer adjustment area is densely provided with strip-shaped liquid inlet channels, and the width of the liquid inlet channel gradually increases along the direction away from the center of the mixed channel. The application enables the liquid phase to not only enter from the liquid suction port but also enter the mixed channel through the liquid inlet channel, and in the process of passing through the liquid inlet channel, breaking and atomization occur, the structure of the gas flow channel is changed, the flow velocity and pressure of the gas-liquid two-phase mixed flow are changed, the turbulence degree when the gas and liquid are mixed is increased, the mixing effect is strengthened, and the uniformity of the flow is effectively increased.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, specifically to a microdroplet gas-liquid distributor, a distribution assembly, and a fixed-bed hydrogenation reactor. Background Technology

[0002] Against the backdrop of increasingly stringent environmental regulations, standards for impurity content in various petroleum products are also rising. Hydrogenation technology, as an indispensable technology in the production of clean fuels, plays a significant role in refinery production. Hydrogenation technology includes hydrocracking and hydrorefining. The hydrogenation reaction is exothermic, and currently, most domestic refineries use a downflow fixed-bed reactor structure. The reactants flow from top to bottom through the catalyst bed and undergo the hydrogenation reaction under its influence. During the reaction, uneven gas-liquid distribution in the bed can lead to hot spots, catalyst coking, and runaway temperatures within the reactor, affecting product quality and causing safety hazards. Therefore, a stable gas-liquid distribution is crucial for improving the flow characteristics and catalyst utilization rate within the reactor. Gas-liquid distribution equipment is an internal component within the reactor that significantly influences the initial gas-liquid distribution.

[0003] Currently, hydrogenation reactors are becoming increasingly larger, making the design of gas-liquid distributors more challenging. When conventional gas-liquid distributors are directly applied to large-scale reactors, uneven gas-liquid distribution between the bed layers is very likely to occur. Summary of the Invention

[0004] To address the issue of uneven distribution that easily occurs when existing gas-liquid distributors are applied to large-scale hydrogenation reactors, this invention provides a micro-droplet gas-liquid distributor, a distribution component, and a fixed-bed hydrogenation reactor. By changing the structure of the gas flow channel, the flow rate and pressure of the gas-liquid two-phase mixture are altered, increasing the turbulence during gas-liquid mixing, enhancing the mixing effect, and effectively increasing the uniformity of the flow.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a micro-droplet gas-liquid distributor, comprising a mixing channel with openings at both ends. The gas phase enters the mixing channel from the gas phase inlet at the top of the mixing channel to generate negative pressure, and then the liquid phase is drawn in by the liquid suction port and mixed with the gas phase, and discharged from the bottom opening of the mixing channel. The liquid suction port divides the mixing channel into a buffer adjustment zone near the gas phase inlet and a liquid storage zone near the bottom opening. The buffer adjustment zone is densely covered with strip-shaped liquid inlet channels, and the width of the liquid inlet channels gradually increases in the direction away from the center of the mixing channel.

[0006] As an optimized solution for the aforementioned microdroplet gas-liquid distributor, the ratio of the lengths of the buffer adjustment zone and the liquid storage zone along the gas-liquid flow direction is 1:1-2.

[0007] As another optimized solution for the above-mentioned micro-droplet gas-liquid distributor, the ratio of the minimum width, maximum width and length of the liquid inlet channel is 1:3-5:2-5, and the ratio of the distance between two adjacent liquid inlet channels to the minimum width of the liquid inlet channel is 1000:1-50.

[0008] As another optimized solution for the aforementioned microdroplet gas-liquid distributor, a baffle is provided above the top of the mixing channel, and a gas phase inlet is formed between the bottom surface of the baffle and the top of the mixing channel.

[0009] As another optimized solution for the aforementioned microdroplet gas-liquid distributor, a diffuser is provided at the bottom opening of the mixing channel, and the bottom of the diffuser is sealed by a sealing plate with gas-liquid outlets densely distributed on its surface.

[0010] As another optimized solution for the aforementioned microdroplet gas-liquid distributor, the sealing plate is made of Johnson mesh, and the gaps in the Johnson mesh form gas-liquid outlets; the cross-section of the metal wires used to make the Johnson mesh is an isosceles triangle, and the tips of the metal wires face the direction of the mixing channel.

[0011] As another optimized solution for the aforementioned microdroplet gas-liquid distributor, the thickness of the Johnson mesh is 2-3 mm, and the narrowest gap between the filaments is 10-30 μm.

[0012] As another optimized solution for the aforementioned microdroplet gas-liquid distributor, the cross-section of the diffuser is an isosceles trapezoid, and the included angle between the extension lines of the two sides of the isosceles trapezoid is 60-120°.

[0013] As another optimized solution for the aforementioned microdroplet gas-liquid distributor, the buffer adjustment zone is a cylindrical structure surrounded by a Johnson mesh, and the gaps in the Johnson mesh form liquid inlet channels; the cross-section of the metal wires used to make the Johnson mesh is an isosceles triangle, and the tips of the metal wires face away from the center of the mixing channel 1.

[0014] As another optimized solution for the aforementioned microdroplet gas-liquid distributor, the thickness of the Johnson mesh is 2-3 mm, and the narrowest gap between the filaments is 10-30 μm.

[0015] As another optimized solution for the aforementioned microdroplet gas-liquid distributor, the liquid suction port consists of two symmetrically arranged circular through holes.

[0016] A microdroplet gas-liquid distribution assembly includes a distribution disk with a plurality of mounting holes distributed on the distribution disk. Each mounting hole contains a microdroplet gas-liquid distributor as described above, and the upper middle part of the liquid storage area is above the distribution disk, while the bottom end of the liquid storage area is below the distribution disk.

[0017] A fixed-bed hydrogenation reactor includes a gas-liquid distribution assembly disposed above a catalyst bed, wherein the gas-liquid distribution assembly is the aforementioned micro-droplet gas-liquid distribution assembly.

[0018] The working principle of this invention is that the gas and liquid phases flow in parallel from top to bottom through the reactor. Due to the large diameter of the reactor and the large density difference between the gas and liquid phases, the gas and liquid phases are unevenly distributed in the radial direction of the reactor during the flow process, and it is also difficult to achieve uniform relative distribution of the gas and liquid phases. The flow is uniformly distributed and mixed by a distribution plate set on the catalyst bed and several distributors on the distribution plate.

[0019] When the gas and liquid phases reach the top of the distributor, they are simultaneously blocked by the baffle above the distributor. The liquid phase accumulates into a liquid layer on the distribution plate below, while the gas phase enters the mixing channel (also known as the central tube) through the gas phase inlet below the baffle. Conventional tubular distributors utilize the acceleration effect of the gas phase entering the central tube from a large space to create a negative pressure in the central tube, drawing the liquid phase on the distribution plate into the central tube for mixing.

[0020] This invention replaces the upper part of the central tube with a Johnson tube, allowing the liquid phase to enter the central tube not only through the liquid phase inlet but also through the gaps in the Johnson tube. Simultaneously, each gap in the Johnson tube is a variable-diameter channel, increasing the flow velocity of the liquid phase as it passes through the narrowing gaps. The sudden increase in the liquid phase space entering the central tube causes a fragmentation and atomization phenomenon. The high-velocity atomized liquid phase collides perpendicularly with the gas in the central tube, enhancing the mixing effect of the distributor. The mixed micro-droplet gas-liquid two-phase fluid flows downward from the central tube to the diffuser. The diffuser, being an umbrella-shaped flow, diffuses and then impacts the lowermost Johnson plate. A portion of the gas-liquid two-phase flow disperses around the impact, undergoing a simple initial distribution. Another portion passes through the gaps in the Johnson plate, where the gaps narrow, similar to passing through a Venturi structure. The liquid and gas phases are fragmented and distributed through several small Venturi structures. Through the design of the physical structure, combining macroscopic distribution with micro-droplet distribution, the mixing and uniformity of the distributor in the hydrogenation reactor is enhanced.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention replaces the upper part of the mixing channel with a buffer adjustment area whose surface is densely covered with specially structured liquid inlet channels. This allows the liquid phase to enter not only from the suction port but also through the liquid inlet channels into the mixing channel. During the process of passing through the liquid inlet channels, the liquid phase is broken up and atomized. By utilizing the structural changes of the gas flow channel, the flow rate and pressure of the gas-liquid two-phase mixing flow are changed, increasing the degree of turbulence during gas-liquid mixing, enhancing the mixing effect, and effectively increasing the uniformity of the flow. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention;

[0024] Figure 2 for Figure 1 Schematic diagram of the cross section of AA;

[0025] Figure 3 A magnified schematic diagram of the tube wall when the buffer adjustment zone is a Johnson net;

[0026] Figure 4 A schematic diagram showing the Johnson plate as the inner sealing plate of the diffuser section;

[0027] Reference numerals: 1. Mixing channel; 101. Buffer adjustment zone; 102. Liquid storage zone; 103. Liquid suction port; 104. Gas phase inlet; 105. Baffle; 106. Sealing plate; 107. Diffusion section; 2. Distribution plate. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not explained in the following embodiments of the present invention are all considered to be prior art known or should be known by those skilled in the art, such as the structure of the distribution disk, the structure and manufacturing method of the Johnson mesh, and how the distributor is installed in the fixed bed hydrogenation reactor.

[0029] Example 1

[0030] A microdroplet gas-liquid distributor, such as Figure 1 As shown, it includes a mixing channel 1 open at both ends. The mixing channel 1 is generally a stainless steel metal pipe open at both ends, with a total length of 50-120mm. The specific dimensions can be determined according to the reactor size, material properties, and throughput. It is generally circular with a diameter of 25-50mm, which can be determined according to the reactor's open-circuit requirements. The gas phase enters the mixing channel 1 through the gas phase inlet 104 at the top, creating a negative pressure. Then, the liquid phase is drawn in through the liquid suction port 103 and mixed with the gas phase. The mixture is then discharged from the bottom opening of the mixing channel 1. The liquid suction port 103 is generally located on the middle side wall of the mixing channel 1 and is generally a circular through hole with a diameter of 7-15mm, specifically 7mm, 9mm, 11mm, 13mm, 15mm, etc. Preferably, the liquid suction port 103 consists of two symmetrically arranged circular through holes. Figure 2 As shown, the suction port 103 divides the mixing channel 1 into a buffer adjustment zone 101 near the gas phase inlet 104 and a liquid storage zone 102 near the bottom opening. The sidewall of the buffer adjustment zone 101 is densely covered with strip-shaped liquid inlet channels, and the width of the liquid inlet channels gradually increases in the direction away from the center of the mixing channel 1, thereby forming a funnel-shaped outward expansion, so that the liquid phase can also enter the mixing channel 1 through these liquid inlet channels.

[0031] In this embodiment, the strip-shaped liquid inlet channel refers to a liquid inlet channel having a certain width and length, with the length being much greater than the width, so that it looks like a narrow slit.

[0032] In this embodiment, the length ratio of the buffer adjustment zone 101 and the liquid storage zone 102 along the gas-liquid flow direction is 1:1-2. In practice, the buffer adjustment zone 101 and the liquid storage zone 102 divide the entire mixing channel 1 into two parts along its length direction. The liquid inlet 103 is located at the upper part of the liquid storage zone 102. The length ratio of the two regions along the gas-liquid flow direction is actually the height ratio of the two regions.

[0033] In this embodiment, the ratio of the minimum width, maximum width, and length of the inlet channel is 1:3-5:2-5, and the ratio of the distance between two adjacent inlet channels to the minimum width of the inlet channel is 1000:1-50. Here, the length of the inlet channel refers to the distance the strip-shaped inlet channel extends through the thickness direction of the buffer adjustment area 101, which is equal to the wall thickness of the buffer adjustment area 101. The minimum width and maximum width refer to the width of the openings of the inlet channel on the inner and outer surfaces of the buffer adjustment area 101, respectively. The distance between two adjacent inlet channels refers to the interval between the two strip-shaped inlet channels. These parameters do not involve the length of the strip-shaped inlet channel.

[0034] In this embodiment, the gas phase generally enters the mixing channel 1 at high speed and generates negative pressure. The purpose is to use negative pressure to draw in the liquid phase. The amount of negative pressure generated by the high flow rate to draw in the liquid phase is affected by factors such as the size of the equipment and the size of the suction port, as well as parameters such as the composition and density of the liquid phase. Therefore, this embodiment does not limit the parameters. In actual application, those skilled in the art need to conduct experiments based on the specific conditions of the equipment to obtain the optimal operating parameters.

[0035] Example 2

[0036] This embodiment is an improvement on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 1As shown, a baffle 105 is located above the top of the mixing channel 1. Since the mixing channel 1 is generally cylindrical, the baffle 105 is also generally circular, and the centers of both are on the same vertical axis. The diameter of the baffle 105 is larger than the diameter of the mixing channel 1, so that the projection of the baffle 105 on the vertical plane completely blocks the mixing channel 1. This causes the gas phase from top to bottom to impact the upper surface of the baffle 105 and be deflected, entering the gas phase inlet 104 horizontally. The bottom surface of the baffle 105 and the top of the mixing channel 1 form the gas phase inlet 104. The baffle 105 is horizontally arranged, and its bottom surface is connected to the top of the mixing channel 1 by at least two connecting rods. Generally, three or four connecting rods are selected and are evenly distributed along the top opening of the mixing channel 1. The gas phase inlet 104 is formed between the connecting rods.

[0037] Example 3

[0038] This embodiment is an improved version based on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 1 As shown, a funnel-shaped outward-expanding diffuser 107 is provided at the bottom opening of the mixing channel 1. The cross-sectional shape of the diffuser 107 is preferably an isosceles trapezoid, and the included angle between the extension lines of the two sides of the isosceles trapezoid is 60-120°. The bottom end of the diffuser 107 is closed by a sealing plate 106 with gas-liquid outlets densely distributed on its surface. The width inside the diffuser 107 gradually increases along the direction from the connection between the top and the mixing channel 1 to the sealing plate 106.

[0039] In this embodiment, the sealing plate 106 is preferably made of Johnson mesh, with a thickness of 2-3 mm and a minimum spacing of 10-30 μm between the wires, specifically 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc. The gaps in the Johnson mesh form gas-liquid outlets; the cross-section of the metal wires used to make the Johnson mesh is an isosceles triangle, and the tips of the metal wires point towards the mixing channel 1, such as... Figure 4 As shown; the vertex angle of an isosceles triangle is generally 20-60°.

[0040] Example 4

[0041] This embodiment is an improved version based on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 1As shown, the buffer adjustment zone 101 is a cylindrical structure formed by a Johnson mesh. The thickness of the Johnson mesh is 2-3 mm (i.e., the thickness of the tube wall), and the narrowest gap between the wires is 10-30 μm, specifically 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc. The liquid storage zone 102 is a metal tube with the same diameter and wall thickness as the cylindrical structure formed by the Johnson mesh, and the two are welded together. A suction port 103 is provided at the junction of the two, and the gaps in the Johnson mesh form a liquid inlet channel. The cross-section of the metal wires used to make the Johnson mesh is an isosceles triangle, and the tips of the metal wires face away from the center of the mixing channel 1. Figure 3 As shown.

[0042] Example 5

[0043] A microdroplet gas-liquid distribution component includes a distribution disk 2 with a plurality of mounting holes distributed on the distribution disk 2. Each mounting hole is provided with a microdroplet gas-liquid distributor as described in Examples 1-4, and the upper middle part of the liquid storage area 102 is above the distribution disk 2, while the bottom end of the liquid storage area 102 is below the distribution disk 2.

[0044] Example 6

[0045] A fixed-bed hydrogenation reactor includes a gas-liquid distribution assembly disposed above a catalyst bed, wherein the structure of the gas-liquid distribution assembly is the microdroplet gas-liquid distribution assembly in Example 5.

Claims

1. A microdroplet gas-liquid distributor, comprising a mixing channel (1) open at both ends, wherein a gas phase enters the mixing channel (1) from the gas phase inlet (104) at the top of the mixing channel (1) to generate a negative pressure, and then a liquid phase is drawn in through the suction port (103) and mixed with the gas phase, and discharged from the bottom opening of the mixing channel (1), characterized in that: The suction port (103) divides the mixing channel (1) into a buffer adjustment zone (101) near the gas phase inlet (104) and a liquid storage zone (102) near the bottom opening. The buffer adjustment zone (101) is densely covered with strip-shaped liquid inlet channels, and the width of the liquid inlet channels gradually increases in the direction away from the center of the mixing channel (1). The bottom opening of the mixing channel (1) is provided with a diffuser (107), and the bottom of the diffuser (107) is closed by a sealing plate (106) with gas-liquid outlets densely distributed on its surface. The sealing plate (106) is made of Johnson mesh, and the gaps in the Johnson mesh form gas-liquid outlets. The cross-section of the metal wires used to make the Johnson mesh is an isosceles triangle, and the tips of the metal wires face the direction of the mixing channel (1). The buffer adjustment area (101) is a cylindrical structure surrounded by Johnson mesh, and the gaps in the Johnson mesh form liquid inlet channels; The cross-section of the metal wire used to make the Johnson mesh is an isosceles triangle, and the tip of the metal wire faces away from the center of the mixing channel (1).

2. The microdroplet gas-liquid distributor according to claim 1, characterized in that: The ratio of the lengths of the buffer regulation zone (101) and the liquid storage zone (102) along the gas-liquid flow direction is 1:1-2.

3. A microdroplet gas-liquid distributor according to claim 1, characterized in that: The ratio of the minimum width, maximum width and length of the liquid inlet channel is 1:3-5:2-5, and the ratio of the distance between two adjacent liquid inlet channels to the minimum width of the liquid inlet channel is 1000:1-50.

4. A microdroplet gas-liquid distributor according to claim 1, characterized in that: The mixing channel (1) has a baffle plate (105) above the top of the mixing channel (1), and a gas phase inlet (104) is formed between the bottom surface of the baffle plate (105) and the top of the mixing channel (1).

5. A microdroplet gas-liquid distributor according to claim 1, characterized in that: The Johnson mesh has a thickness of 2-3 mm and the narrowest gap between the wires is 10-30 μm.

6. A microdroplet gas-liquid distributor according to claim 1, characterized in that: The cross-section of the diffuser (107) is an isosceles trapezoid, and the included angle between the extension lines of the two sides of the isosceles trapezoid is 60-120°.

7. A microdroplet gas-liquid distributor according to claim 1, characterized in that: The liquid suction port (103) consists of two symmetrically arranged circular through holes.

8. A microdroplet gas-liquid distribution component, comprising a distribution disk (2), characterized in that: A plurality of mounting holes are distributed on the distribution plate (2), and a micro-droplet gas-liquid distributor as described in any one of claims 1-7 is provided in each mounting hole, and the upper middle part of the liquid storage area (102) is above the distribution plate (2), and the bottom end of the liquid storage area (102) is below the distribution plate (2).

9. A fixed-bed hydrogenation reactor, comprising a gas-liquid distribution assembly disposed above a catalyst bed, characterized in that: The gas-liquid distribution component is the microdroplet gas-liquid distribution component as described in claim 8.

Images