Fixed bed reactor comprising liquid distribution device and method for heterogeneous catalytic reactions using such reactor

Abstract

The invention discloses a liquid distribution device for a reactor, the liquid distribution device comprises a heat exchange tube unit, the heat exchange tube unit comprises a plurality of vertically arranged heat exchange tubes, left-handed or right-handed spiral fins are arranged on the outer walls of at least one part of the heat exchange tubes, and the heat exchange tubes are arranged in the heat exchange tube unit; the rotating directions of the outer wall spiral fins of at least one part of the heat exchange tubes are opposite to those of the outer wall spiral fins of the adjacent heat exchange tubes; the heat exchange medium flows in the heat exchange tube, and the liquid reaction material flows outside the heat exchange tube in a direction almost parallel to the axial direction of the heat exchange tube; and the optional solid particle filling unit comprises solid particles filled in spaces among the heat exchange tubes. The invention also discloses a multiphase reaction method using the reactor comprising the liquid distribution device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heterogeneous catalytic reaction, in particular to a liquid distribution device, a reactor comprising the liquid distribution device and a method for heterogeneous catalytic reaction using the reactor. BACKGROUND

[0002] Heterogeneous catalytic reaction refers to a chemical reaction of one or more reactants on an interface, such as the surface of a solid catalyst. Heterogeneous catalytic reaction is usually carried out in a fixed bed reactor, a fluidized bed reactor, a moving bed reactor, a feed bed reactor and a rotating bed reactor.

[0003] Fixed bed reactors are widely used in the chemical industry, and have the advantages of small volume, high reaction rate and easy control. Among them, the fixed tube fixed bed reactor is often used for strong exothermic reaction system. The reactor structure is similar to the fixed tube plate heat exchanger. The tube is the reaction zone, the catalyst is filled in the tube, the material reacts when passing through the catalyst in the tube, and the shell space is filled with heat exchange medium to form a reaction heat exchange system. Common applications of fixed tube fixed bed reactors include methanol synthesis column, ethylene oxide reactor, acrylic acid reactor and coal-to-ethanol reactor, etc.

[0004] Sasol and Shell have developed fixed bed reactors for Fischer-Tropsch synthesis in industry. The catalyst is filled in the tube of the reactor, and water is used between the tubes to generate steam to take out the heat from the reactor. Fischer-Tropsch reaction is a strong exothermic reaction, and there is a phenomenon of uneven temperature in the radial and axial directions of the fixed bed reactor. The current method to control the uniformity of the bed temperature is to reduce the pipe diameter, but in a smaller pipe diameter, the synthesis gas is easy to occur carbon deposition reaction on the surface of the catalyst, and local overheating phenomenon occurs, causing the catalyst to break and deactivate.

[0005] Improvements of fixed tube fixed bed reactors in the field are in many aspects, including the development from traditional fixed tube structure to bayonet tube, self-cooling, split tube bundle, sheet, winding tube and other structures, in order to improve the space utilization of the reactor, reduce the energy consumption of the device and the manufacturing difficulty of the reactor, and improve the production capacity of a single reactor under the premise of ensuring the heat exchange effect.

[0006] However, the heat transfer problem of the fixed bed reactor applied in the strong exothermic reaction system is a technical problem. Researchers have improved the heat transfer efficiency of the fixed bed reactor by changing the shape of the filler and optimizing the fluid dynamics.

[0007] CN101480595B proposes using needle-finned heat exchange tubes to simultaneously address both flow field control and heat transfer enhancement. On one hand, the needle fins reduce liquid velocity and axial backmixing; on the other hand, the fins increase the heat exchange area, and the resulting secondary turbulence increases the heat transfer coefficient, offsetting the negative effect of reduced convective heat transfer coefficient caused by decreased liquid velocity. However, while this measure solves the heat transfer and backmixing problems, the collision between the needle fins and catalyst particles will cause catalyst wear, which will reduce catalyst reactivity, weaken the separation efficiency between catalyst particles and liquid, and increase the frequency of catalyst replacement.

[0008] Fixed-bed reactors are primarily used in gas-solid reaction systems and rarely in liquid-solid reaction systems. Compared to gas-solid reaction systems, liquid-solid reaction systems have lower liquid hourly space velocities. Because liquids differ significantly from gases in density and viscosity, the fluid motion distribution patterns in liquid-solid systems differ considerably from those in gas-solid systems. This is especially true for strongly exothermic liquid-solid reaction systems, where conventional fixed-bed reactors struggle to efficiently remove heat, thus typically limiting the reaction rate to lower levels.

[0009] Heat exchange tubes with helical fins are generally used for fluids with high flow velocities, such as gas-solid reaction systems. This is because the helical fins or threads of the heat exchange tubes disturb the high-speed flow of the fluid, continuously disrupting the fluid boundary layer and effectively improving the heat transfer coefficient, resulting in enhanced heat transfer. For example, Chinese patent application CN209222077 discloses a heat transfer system for a Fischer-Tropsch synthesis reactor. This system includes heat exchange elements and a steam drum, with the heat exchange elements disposed within the reactor. The heat exchange tubes can take three structural forms, the most common being smooth metal tubes, but also metal tubes with pin fins and / or metal tubes with external threaded grooves. The Fischer-Tropsch synthesis reactor is a three-phase slurry-bed Fischer-Tropsch synthesis reactor or a fluidized bed Fischer-Tropsch synthesis reactor.

[0010] Ethylene glycol is an aliphatic diol with important applications in the chemical industry. It is typically produced in a fixed-bed reactor using a multiphase catalytic hydration process. For example, Chinese patent application CN101306984A discloses a fixed-bed reactor for the catalytic hydration of ethylene oxide to ethylene glycol. This reactor uses a U-shaped tube array to pack the catalyst, which helps to address catalyst expansion and optimize heat transfer. However, the U-shaped tubes can cause channeling along the tube walls during flow, resulting in uneven distribution of the liquid in the radial direction of the fixed bed. A disc-shaped redistributor has limited effectiveness in mitigating this channeling. Channeling affects feed conversion and selectivity. Furthermore, the channeling effect leads to a thicker liquid film on the outside of the U-shaped tubes, increasing heat transfer resistance and reducing the heat transfer capacity of the U-shaped tube array. Additionally, using different specifications of the U-shaped tubes with the inlet and outlet located on opposite sides of the reactor creates a temperature difference in the reactor bed, further affecting conversion and yield. The thermal stress caused by temperature differences can also shorten the service life of the reactor.

[0011] In order to overcome the above-mentioned problems in the prior art, there is an urgent need for a liquid distribution device that can effectively avoid channeling and make the reaction liquid distribution in the catalyst particle packing zone more uniform, as well as a fixed bed reactor containing the liquid distribution device. Summary of the Invention

[0012] Through research, the inventors surprisingly discovered that the aforementioned problems can be overcome by using a specific liquid distribution device or a reactor containing such a device, wherein the liquid distribution device comprises multiple heat exchange tubes with a specific arrangement of spiral fins on the outer wall. The inventors found that when this reactor is used in a liquid-solid reaction system with a low flow rate of the reactant liquid, the liquid distribution device strongly promotes the reaction and significantly improves the reaction selectivity. Unbound by specific theories, the inventors believe that when these specifically arranged heat exchange tubes with spiral fins on the outer wall are used in a liquid-solid reaction system with a low flow rate of the reactant liquid, the main function of the spiral fins is to change the flow direction of the fluid, promoting radial flow and causing the fluids with nearly equal residence times to split and merge radially, preventing back-mixing of fluids with different residence times in the axial direction. This results in a uniform radial temperature distribution of the reactants, thereby precisely controlling the reaction process and significantly improving the reaction selectivity. In fact, based on published literature, those skilled in the art generally believe that, since the spiral fins on the outer wall of the heat transfer tube have a very small disturbance effect on the flow state of the low-speed liquid, they will not damage the fluid boundary layer and have no significant impact on the mass and heat transfer of the liquid-solid reaction system. In particular, they have a very small impact on the reaction performance of fixed-bed reactors using very low liquid hourly space velocities. Therefore, heat transfer tubes with spiral fins on the outer wall will not be selected for use in fixed-bed reactors using very low liquid hourly space velocities.

[0013] Therefore, one object of the present invention is to provide a liquid distribution device for a reactor or a reactor comprising the liquid distribution device, which can not only effectively avoid the problem of uneven fluid distribution in the solid particle packing zone caused by channeling phenomenon on the outer wall of the heat exchange tube, but also effectively reduce the liquid film thickness of the laminar layer at the liquid-solid interface to enhance reaction kinetics. In addition, it can also improve the uniformity of enhanced heat transfer on the outer and inner walls of the heat exchange tube, and reduce heat transfer resistance, thermal stress and reactor pressure drop.

[0014] To achieve the above objectives, the present invention provides a liquid distribution device for a reactor or a reactor including the liquid distribution device, particularly a fixed-bed reactor. The liquid distribution device allows the reaction liquid to be uniformly distributed radially in the reactor, always maintaining a plug flow pattern, reducing axial backmixing of the reaction liquid, reducing reactor pressure drop, and effectively removing a large amount of heat released by the reaction system, reducing the temperature of the reaction hotspot, so that the temperature distribution inside the reactor is uniform, thereby improving the inherent safety of the reactor.

[0015] Reactors incorporating such liquid distribution devices, particularly fixed-bed reactors, are especially suitable for processes such as the reaction of ethylene oxide (liquid) with water (liquid) in the presence of a solid resin catalyst to produce ethylene glycol, the reaction of ethylene oxide (liquid) with ethylene glycol (liquid) in the presence of a solid resin catalyst to produce diethylene glycol, the reaction of ethylene oxide (liquid) with diethylene glycol (liquid) in the presence of a solid resin catalyst to produce triethylene glycol, the reaction of propylene oxide (liquid) with water (liquid) in the presence of a solid resin catalyst to produce propylene glycol, and the reaction of ethylene oxide (liquid) with water (liquid) in the presence of a solid resin catalyst to produce butanediol. These reactors ensure uniform distribution of the reaction liquid while rapidly removing the heat generated by the reaction, thereby ensuring uniform temperature distribution in the reaction zone and greatly guaranteeing the inherent safety of the chemical process.

[0016] Therefore, according to a first aspect of the present invention, the present invention provides a liquid distribution device for a reactor, wherein the liquid distribution device comprises:

[0017] A heat exchange tube unit comprises a plurality of vertically arranged heat exchange tubes, wherein at least a portion, preferably all, of the heat exchange tubes are provided with left-handed or right-handed helical fins on their outer walls, wherein the helical fins on the outer walls of at least a portion of the heat exchange tubes rotate in the opposite direction to the helical fins on the outer walls of their adjacent heat exchange tubes (i.e., the helical fins on the outer walls of at least a portion of the adjacent heat exchange tubes alternate between left-handed and right-handed rotation), more preferably, the helical fins on the outer walls of all the heat exchange tubes rotate in the opposite direction to the helical fins on the outer walls of their adjacent heat exchange tubes (i.e., the helical fins on the outer walls of all adjacent heat exchange tubes alternate between left-handed and right-handed rotation); the heat exchange medium flows inside the heat exchange tubes, while the liquid reactant flows outside the heat exchange tubes in a direction almost parallel to the axial direction of the heat exchange tubes;

[0018] An optional solid particle packing unit includes solid particles filling the space between heat exchange tubes. Preferably, the solid particle packing unit is a packed bed or a catalyst bed, more preferably a catalyst bed.

[0019] Furthermore, the present invention also provides a reactor including the above-described liquid distribution device, particularly a fixed-bed reactor.

[0020] According to a second aspect of the invention, the invention also provides a method for carrying out heterogeneous catalytic reactions, particularly liquid-solid catalytic reactions, using a reactor comprising the above-described liquid distribution device.

[0021] After in-depth research, the inventors surprisingly discovered that the uniform temperature distribution of the outer wall of the heat exchange tube can promote the uniform distribution of the reaction fluid. When the reactor containing the liquid distribution device according to the present invention is used for liquid-solid reaction, since the spiral fins on the outer wall of the adjacent heat exchange tubes alternate between left-handed and right-handed spirals, the liquid reactants are continuously divided and merged under the combined guiding effect of the left-handed and right-handed spiral fins on the outer wall of the adjacent heat exchange tubes. This restricts the back-mixing of reactants with different residence times in the reactor axis, thereby significantly improving the uniformity of the composition distribution of the liquid reactants in the radial direction. This significantly improves the conversion rate, kinetics, and selectivity of the reaction. In addition, the spiral fins on the outer wall of the heat exchange tube also provide the speed at which the reaction heat is transferred through the heat exchange tube.

[0022] More specifically, the liquid reactants react on the surface of the catalyst particles packed between the heat exchange tubes. Under the combined action of the left-handed and right-handed spiral fins on the outer wall of the adjacent heat exchange tubes and the catalyst particles, the liquid reactants are further homogenized radially, resulting in a more uniform temperature distribution radially. Consequently, the composition of the reactants is more uniformly distributed radially, thereby significantly improving reaction kinetics and reaction selectivity.

[0023] Unrestricted by any particular theory, the inventors discovered through research that, for a reactor incorporating the liquid distribution device according to the present invention, when the following conditions are met: the liquid distribution device includes a solid particle packing unit; the dimensions of each heat exchange tube are identical and uniformly arranged; the inlet and outlet ends of two adjacent U-shaped heat exchange tubes, or the inlet ends of four adjacent straight heat exchange tubes, are arranged in a square, the side length of the square is W, and the diameter of the heat exchange tube is D (see Appendix). Figure 5 The outer wall spiral fins of the heat exchange tube have a triangular cross-section, with half the length of the base of the triangle being h and half the length of the apex being θ. The pitch of the spiral fins is H and the diameter of the heat exchange tube is D. The fixed bed height is l and the number average diameter of the solid particles is d. Then the heat transfer coefficient of the reactor containing the liquid distribution device and the structural parameters of the spiral fins and the arrangement structural parameters of the heat exchange tube satisfy the following relationship (1):

[0024]

[0025] In the above formula, the characteristic size D e Characteristic dimensions expressed in meters (m): α represents the heat transfer coefficient of the reactor (W / (m²)). 2 ·K)); Re represents the Reynolds coefficient. ρ represents the density of the reacting liquid (kg / m³). 3 μ represents the viscosity of the reactant liquid (Pa·s); Pr (Prand number) represents the physical property constant. where c p represents the specific heat capacity at constant pressure of the liquid (J / (kg·°C)), λ represents the thermal conductivity of the liquid (W / (m·K)); u represents the flow velocity of the reaction liquid (m / s), and its calculation method is as follows: Set a certain space velocity, such as 1.1 h -1 , when the volume of the catalyst loaded in the reactor is determined, the total feed volume flow rate can be determined. According to the number of repeating units in the catalyst loading area of the reactor shown in the appendix Figure 5 , calculate the feed volume flow rate of a single repeating unit, and then divide the feed volume flow rate of a single repeating unit by the cross-sectional area of a single repeating unit to obtain the flow velocity u (since the reaction tube is filled with catalyst, the cross-sectional area of the reaction tube will become smaller and the actual velocity will become larger. The velocity calculated by this method is equivalent to the empty tube velocity of the liquid passing through the reaction tube when the reaction tube is not filled with catalyst); W and D are as shown in the appendix Figure 5 , when the heat exchange tubes are arranged in a square pattern, W represents the side length of the square (m), and D represents the diameter of the heat exchange tube (m); H and h respectively represent the pitch of the triangular spiral fins (m) and half of the base length of the cross-section of the triangular spiral fins (m); θ is half of the apex angle of the triangular spiral fins (in radians); M and N are dimensionless constants, where M is related to the rotation direction of the rotating fins on the inner and outer walls of the heat exchange tube, and different rotation directions have different values; when the rotation directions of the outer wall spiral fins of all heat exchange tubes are the same, N = 0.37; when the rotation direction of the outer wall spiral fins of all heat exchange tubes is opposite to that of the outer wall spiral fins of the adjacent arranged heat exchange tubes, N = 0.88; when the rotation direction of the outer wall spiral fins of the heat exchange tube is opposite to that of the inner wall spiral fins of the heat exchange tube, M = 1.18, and when the rotation directions are the same, M = 1.

[0026] For highly exothermic reactions occurring in a reactor containing the liquid distribution device of the present invention, the hot spot temperature rise of the reactor can be effectively controlled by a sufficiently high heat transfer coefficient α. According to a preferred embodiment, in the above formula (1), α > 30 W / (m 2 ·K), preferably α > 50 W / (m 2 ·K); more preferably α > 70 W / (m 2 ·K); even more preferably α > 90 W / (m 2 ·K).

[0027] Since the reactor containing the liquid distribution device of the present invention is more suitable for liquid-solid reaction systems with low liquid hourly space velocity, according to one embodiment, in formula (1), 0.6 < Re < 50, preferably 1 < Re < 35, more preferably 2 < Re < 10.

[0028] After multiple experimental verifications, the above formula is particularly applicable to the case where the liquid is in a laminar flow state in the reactor of the present invention. When 0.6 < Re < 50 and 1 < Pr < 3, the calculation error is within plus or minus 15%, and even most of it is within plus or minus 10%. Since Pr will decrease as the temperature increases, for the liquid (temperature greater than 80 °C) in the reactor of the present invention, Pr all meets this requirement.

[0029] According to the third aspect of the present invention, the present invention also provides a method for improving the temperature distribution of a fixed-bed reactor, wherein the liquid distribution device of the present invention is used in the fixed-bed reactor. Brief Description of the Drawings

[0030] Figure 1 It is a schematic structural view of a reactor according to an embodiment of the present invention.

[0031] Figure 2 It is a schematic assembled structural view of a liquid distribution device according to an embodiment of the present invention (the spiral fins are not shown).

[0032] Figure 3 It is a schematic view of a heat exchange tube with outer-wall spiral fins according to the present invention and a partial enlarged view of the spiral fins.

[0033] Figure 4 It is a schematic cross-sectional view of a heat exchange tube with outer-wall spiral fins according to the present invention (the cross-sectional shape of the spiral fins is an isosceles triangle).

[0034] Figure 5 It is a schematic view of the arrangement position of the heat exchange tubes and the catalyst loading area according to the present invention.

[0035] Figure 6 It is a schematic structural view of a liquid reaction material distributor according to the present invention.

[0036] Figure 7 It is a partial structural schematic view of the left-handed and right-handed outer-wall spiral fins of two adjacent heat exchange tubes according to the present invention.

[0037] Figure 8 It is a schematic cross-sectional view of a heat exchange tube with both outer-wall and inner-wall spiral fins according to the present invention (the cross-sectional shape of the spiral fins is an isosceles triangle).

[0038] Figure 9 It is a schematic view in which the rotation directions of the outer-wall spiral fins and the inner-wall spiral fins of the heat exchange tube are opposite, wherein the outer-wall spiral fins (represented by solid lines) are right-handed and the inner-wall spiral fins of the tube (represented by dashed lines) are left-handed.

[0039] Figure 10This is a schematic diagram showing that the spiral fins on the outer wall of the heat exchange tube and the spiral fins on the inner wall of the heat exchange tube rotate in the same direction. The spiral fins on the outer wall (represented by solid lines) are right-handed, and the spiral fins on the inner wall of the tube (represented by dashed lines) are right-handed.

[0040] Figure 11 This is a diagram showing the flow effect of the reaction fluid when all heat exchange tubes with right-handed outer spiral fins are arranged.

[0041] Figure 12 This is a diagram showing the flow effect of the reaction fluid when heat exchange tubes with left-handed outer spiral fins and right-handed outer spiral fins are arranged alternately in an axially asymmetrical manner.

[0042] Figure 13 This is a diagram showing the flow effect of the reaction fluid when heat exchange tubes with left-handed outer spiral fins and right-handed outer spiral fins are arranged alternately in an axially symmetrical manner.

[0043] Explanation of key figure labels:

[0044] 100: Fixed-bed reactor

[0045] 101: Liquid outlet;

[0046] 1: U-shaped heat exchange tube,

[0047] 1A: Heat exchange medium inlet,

[0048] 1B: Heat exchange medium outlet,

[0049] 10: Spiral fins,

[0050] 10A: Left-handed spiral fins,

[0051] 10B: Right-handed spiral fins,

[0052] 11: Support plate on heat exchanger tubes

[0053] 12: Lower support plate for heat exchanger tubes

[0054] 13: Heat exchange medium inlet main pipe,

[0055] 14: Main outlet pipe for heat exchange medium;

[0056] 2: Liquid reactant distributor

[0057] 21: Liquid outlet hole;

[0058] 3: Catalyst loading area

[0059] 31: Top screen of catalyst,

[0060] 32: Bottom screen of the catalyst. Detailed Implementation Plan

[0061] Other features and advantages of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments thereof.

[0062] It should be understood that the specific embodiments described in this specification are for illustrative and explanatory purposes only and are not intended to limit the invention.

[0063] Any specific numerical value (including the endpoints of a range) disclosed in this specification is not limited to its exact value, but should be understood to also include values ​​close to that exact value, such as all possible values ​​within ±5% of that exact value. Furthermore, with respect to the disclosed numerical range, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed in this specification.

[0064] Unless otherwise stated, the terms used in this specification have the same meaning as commonly understood by those skilled in the art. If a term is defined in this specification and its definition differs from the common understanding in the art, the definition in this specification shall prevail.

[0065] In this specification, except where expressly stated, any matters or issues not mentioned herein shall apply directly to those known in the art without any modification. Furthermore, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the resulting technical solutions or ideas shall be considered part of the original disclosure or original record of this invention, and should not be regarded as new content not disclosed or anticipated in this specification, unless those skilled in the art consider such combination to be clearly unreasonable.

[0066] All patent and non-patent literature mentioned in this specification, including but not limited to textbooks and journal articles, are incorporated in full by way of citation.

[0067] According to a first aspect of the present invention, the present invention relates to a liquid distribution device for a reactor, the liquid distribution device comprising:

[0068] A heat exchange tube unit comprises a plurality of vertically arranged heat exchange tubes, wherein at least a portion, preferably all, of the heat exchange tubes are provided with left-handed or right-handed helical fins on their outer walls, wherein the helical fins on the outer walls of at least a portion of the heat exchange tubes rotate in the opposite direction to the helical fins on the outer walls of their adjacent heat exchange tubes (in other words, the helical fins on the outer walls of at least a portion of the adjacent heat exchange tubes alternate between left-handed and right-handed rotation), more preferably, the helical fins on the outer walls of all the heat exchange tubes rotate in the opposite direction to the helical fins on the outer walls of their adjacent heat exchange tubes (in other words, the helical fins on the outer walls of all the adjacent heat exchange tubes alternate between left-handed and right-handed rotation); the heat exchange medium flows inside the heat exchange tubes, while the liquid reactant flows outside the heat exchange tubes in a direction almost parallel to the axial direction of the heat exchange tubes;

[0069] An optional solid particle filling unit includes solid particles that fill the space between the heat exchange tubes.

[0070] Furthermore, the present invention also provides a reactor including the above-described liquid distribution device, particularly a fixed-bed reactor.

[0071] According to one embodiment of the present invention, the reactor including the liquid distribution device is a fixed-bed reactor for a liquid-solid reaction system, wherein the solid bed can be a solid packing bed or a solid catalyst bed, comprising granular packing or solid catalyst filling the space outside any heat exchange tube.

[0072] According to one embodiment of the present invention, the heat exchange tube unit includes a plurality of vertically arranged heat exchange tubes, the heat exchange tubes being selected from straight heat exchange tubes or U-shaped heat exchange tubes, preferably U-shaped heat exchange tubes; each heat exchange tube has left-handed or right-handed helical fins on its outer wall, wherein at least a portion of the outer wall helical fins of the heat exchange tubes rotate in the opposite direction to the outer wall helical fins of their adjacent heat exchange tubes (in other words, at least a portion of the outer wall helical fins of their adjacent heat exchange tubes rotate in alternating left-handed and right-handed directions), more preferably, all the outer wall helical fins of the heat exchange tubes rotate in the opposite direction to the outer wall helical fins of their adjacent heat exchange tubes (in other words, all the outer wall helical fins of their adjacent heat exchange tubes rotate in alternating left-handed and right-handed directions).

[0073] It should be understood that when the heat exchange tube is a U-shaped heat exchange tube, the rotation direction of the outer wall spiral fins of the straight tube portion of the U-shaped heat exchange tube can be the same or different from each other. In this case, one U-shaped heat exchange tube with outer wall spiral fins is equivalent to two straight tube heat exchange tubes with outer wall spiral fins having the same or opposite rotation directions.

[0074] In this specification, the term "adjacent heat exchange tubes" means that two heat exchange tubes are arranged such that the distance between their axial centers is smaller than the distance between their axial centers and the axial centers of other heat exchange tubes. If the axial center of a heat exchange tube is the same as and the smallest distance between the axial centers of multiple heat exchange tubes, then the heat exchange tube is simultaneously arranged adjacent to the multiple heat exchange tubes.

[0075] According to a preferred embodiment, when the pitch of the spiral fins is H and the diameter of the heat exchange tube is D, the ratio H / D is 0.2-1.7, preferably 0.3-1.3, for example 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 and 1.2, wherein the above H and D are in the same unit of length.

[0076] According to a preferred embodiment, each heat exchange tube has the same dimensions and is evenly arranged in the liquid distribution device. Preferably, the inlet and / or outlet ends of two adjacent U-shaped heat exchange tubes or four adjacent straight heat exchange tubes are arranged in a square, wherein the side length of the square is W and the diameter of the heat exchange tube is D, such that W / D = 1.2-3, preferably 1.5-2.5, more preferably 1.8-2.4, for example 1.9, 2.0, 2.1, 2.2 and 2.3, wherein W and D are in the same unit of length.

[0077] According to a preferred embodiment, the diameter D and wall thickness of the heat exchange tube can be determined by those skilled in the art based on actual needs and their basic knowledge. For example, the diameter D can typically be 7-35 mm; preferably 10-25 mm, and the wall thickness can be about 1 mm.

[0078] According to a preferred embodiment, the liquid reactant flows from top to bottom outside the heat exchange tube, and the overall flow direction is preferably substantially parallel to the axis of the heat exchange tube.

[0079] The inventors, through further research, surprisingly discovered that in the liquid distribution device of the present invention, the combination of the structural characteristics of solid particles, such as catalyst particles (particularly particle sphericity and number-average diameter) with the structural characteristics of the spiral fins on the outer wall of the heat exchange tube has a synergistic effect on further improving the performance of the reactor, making the fixed-bed reactor of the present invention highly suitable for liquid-solid catalytic reactions. According to a specific embodiment, the catalyst bed comprises nearly spherical solid catalyst particles of substantially equal size, having a sphericity greater than 0.8, preferably greater than 0.85, more preferably greater than 0.9. The sphericity is measured using the surface area method well known in the art. Preferably, the number-average diameter of the solid catalyst particles is d, such that d / W is 0.01-0.2, preferably 0.02-0.1, wherein W and d are in the same unit of length.

[0080] According to a preferred embodiment, the heat exchange tube is a U-shaped heat exchange tube, wherein the inlet end and outlet end of each U-shaped heat exchange tube are located on the same side and spaced apart, preferably located on the upper side of the reactor. Furthermore, support plates are provided at both the upper and lower ends of the heat exchange tube to keep it upright.

[0081] According to a preferred embodiment, spiral fins are provided on the inner wall of at least a portion, preferably all, of the heat exchange tubes. The spiral fins on the outer wall of the heat exchange tubes and the spiral fins on the inner wall of the heat exchange tubes may rotate in the same or opposite directions, preferably opposite directions.

[0082] According to a preferred embodiment, the spiral fin is a protruding structure on the outer and / or inner wall of the heat exchange tube, wherein the cross-sectional shape of the protruding structure is triangular, semi-circular, semi-elliptical, or rectangular. When the cross-sectional shape of the protruding structure is triangular, it is preferably a near-isosceles triangle, more preferably an isosceles triangle. The term "near-isosceles triangle" means that the length difference between the two sides of the protrusion on the outer and / or inner wall of the cross-section of the spiral fin is less than 10%, preferably less than 5%, and more preferably equal.

[0083] According to a preferred embodiment, when the cross-sectional shape of the protrusion structure is triangular, half of the base of the triangle is h and half of the vertex angle is θ, the ratio h / D is 0.03-0.1, preferably 0.05-0.09, and θ is 10° to 60°, preferably 20° to 50°, for example 25°, 30°, 35°, 40° or 45°, wherein the above-mentioned degree and radian values ​​of angle θ can be converted to each other.

[0084] According to a preferred embodiment, the rotation direction of the outer wall spiral fins can be the same as or opposite to the rotation direction of the inner wall spiral fins of the heat exchange tube, preferably opposite.

[0085] According to a preferred embodiment, the outer wall spiral fins of all heat exchange tubes have the same pitch H and the same cross-sectional shape; the inner wall spiral fins of all heat exchange tubes have the same pitch H and the same cross-sectional shape.

[0086] According to a preferred embodiment, the pitch H of the outer wall spiral fins and the pitch H' of the inner wall spiral fins of the heat exchange tube can be the same or different. However, the inventors have found that it is particularly advantageous when the pitch H' of the inner wall spiral fins of the heat exchange tube is 1-5 times, preferably 2-3 times, the pitch H of the outer wall spiral fins. This is because it significantly simplifies the manufacturing process of the inner wall spiral fins and saves manufacturing costs without affecting, and even improves, the heat transfer efficiency, temperature uniformity, and uniform distribution of liquid reactants outside the heat exchange tube.

[0087] According to a preferred embodiment, if the rotation direction of the outer wall spiral fins of the heat exchange tube is the same as that of the inner wall spiral fins and the pitch H of the outer wall spiral fins is the same as that of the inner wall spiral fins, it is advantageous to offset the outer wall spiral fins of the heat exchange tube from the inner wall spiral fins by at least 1 / 4 pitch, preferably 1 / 2 pitch, in the axial direction; or if the rotation direction of the outer wall spiral fins of the heat exchange tube is opposite to that of the inner wall spiral fins and the pitch H of the outer wall spiral fins is the same as that of the inner wall spiral fins, it is advantageous to offset the outer wall spiral fins of the heat exchange tube from the inner wall spiral fins by at most 1 / 4 pitch, preferably no offset.

[0088] According to a preferred embodiment, the liquid distribution device further includes a liquid distributor located above the heat exchange tube unit, and the opening ratio of the liquid distributor outlet is 2‰-75‰, preferably 10‰-60‰, for example 20‰, 30‰, 40‰, or 50‰.

[0089] According to a preferred embodiment, the left-handed and right-handed spiral fins of any pair of adjacent heat exchange tubes are misaligned in the axial direction by at most 1 / 3 of the pitch, preferably at most 1 / 4 of the pitch, and more preferably, the left-handed and right-handed spiral fins of any pair of adjacent heat exchange tubes are not misaligned in the axial direction, that is, they are mirror-symmetrically distributed with respect to the axial direction.

[0090] According to a preferred embodiment, the solid particle loading unit is provided with screens at both the upper and lower ends; the lower screen is located below the bottom of the heat exchange tube, which can prevent catalyst particles from leaking out from the gap at the contact point between the screen and the heat exchange tube with rotating fins on the outer wall, and the upper screen is located below the liquid distributor.

[0091] According to a preferred embodiment, the heat exchange medium inlet manifold and / or heat exchange medium outlet manifold of the reactor are located at the top of the reactor and are positioned higher than the liquid distributor.

[0092] According to a preferred embodiment, the reactor of the present invention is a multiphase catalytic reactor, used for catalytic hydration reactions to prepare ethylene glycol, catalytic reactions to prepare diethylene glycol, catalytic reactions to prepare triethylene glycol, catalytic reactions to prepare propylene glycol, or catalytic reactions to prepare butanediol, wherein the liquid reactants are liquid ethylene oxide and liquid water, liquid ethylene oxide and liquid ethylene glycol, liquid ethylene oxide and liquid diethylene glycol, liquid propylene oxide and liquid water, or liquid butane oxide and liquid water; and the solid catalyst used is selected from resins.

[0093] According to a second aspect of the invention, the invention also relates to a method for carrying out a heterogeneous catalytic reaction, characterized in that a reactor, particularly a fixed-bed reactor, incorporating the liquid distribution device of the invention as described above is used.

[0094] According to a preferred embodiment, the method is used to prepare ethylene glycol via catalytic hydration of ethylene oxide, diethylene glycol via catalytic reaction of ethylene oxide and ethylene glycol, triethylene glycol via catalytic reaction of ethylene oxide and diethylene glycol, propylene glycol via catalytic hydration of propylene oxide, or butanediol via catalytic hydration of butane oxide, wherein the liquid reactants are liquid ethylene oxide and liquid water, liquid ethylene oxide and liquid ethylene glycol, liquid ethylene oxide and liquid diethylene glycol, liquid propylene oxide and liquid water, or liquid butane oxide and liquid water; and the solid catalyst used is selected from resins.

[0095] According to a preferred embodiment, the method is used to prepare ethylene glycol via a catalytic hydration reaction of ethylene oxide, wherein the liquid reactants are liquid ethylene oxide and liquid water, and the solid catalyst used is a resin.

[0096] According to a preferred embodiment, the method is used to prepare ethylene glycol via a catalytic hydration reaction of ethylene oxide, wherein the liquid reactants are liquid ethylene oxide and liquid water, and the molar ratio of liquid water to liquid ethylene oxide is less than or equal to 10:1, preferably less than or equal to 6:1, for example 5:1, 4:1, or 3:1.

[0097] According to a preferred embodiment, liquid ethylene oxide and liquid water flow through a fixed-bed reactor, contacting and reacting with a solid catalyst bed packed outside heat exchange tubes to produce ethylene glycol. The reaction temperature is 85-150°C, preferably 90-140°C; the pressure is 1.0-1.8 MPa, preferably 1.1-1.7 MPa, for example 1.2 MPa, 1.4 MPa, or 1.6 MPa; and the liquid hourly space velocity is 0.5-5 h⁻¹. -1 Preferably 1-4h -1 For example, 2h -1 3h -1 .

[0098] In the prior art, heat exchange tubes with spiral fins on the outer wall are generally used in heat exchangers, and typically employ methods such as... Figure 11 The spiral fins on the outer wall shown are all arranged in a right-handed or left-handed manner. However, the inventors discovered through research that using heat exchange tubes with spiral fins on the outer wall in a fixed-bed reactor, and allowing the reaction fluid to flow outside the heat exchange tube in a direction parallel to the axial direction of the heat exchange tube, can significantly improve the reaction kinetics of the reaction fluid, control its reaction rate, and significantly improve its reaction yield and selectivity while effectively transferring heat.

[0099] The inventors further discovered that when all the spiral fins on the outer wall of the arranged heat exchange tubes are right-handed, the fluid tends to deflect to the left, reflecting the fluid flow effect as follows: Figure 11 As shown, when all the spiral fins on the outer wall of the arranged heat exchange tubes are left-handed, the fluid tends to flow to the right. Because the unidirectional flow of the reaction fluids lacks mixing, this flow results in a radially uneven temperature distribution of the reaction fluids in the catalyst-filled space. This leads to a non-uniform distribution of both composition and temperature in the fixed bed, severely affecting reaction kinetics, yield, and selectivity.

[0100] The inventors also discovered that, such as Figure 12 As shown, when heat exchange tubes with left-handed outer wall spiral fins and heat exchange tubes with right-handed outer wall spiral fins are arranged alternately in a heat exchange tube unit, but the spiral fins on the outer walls of the two heat exchange tubes are misaligned by more than one-third of the pitch in the axial direction, although the reactant fluid produces an alternating flow effect of splitting and converging in the radial direction of the reactor, stream a and stream b still have different flow paths and different residence times in the reactor. When they converge, a back-mixing effect will occur. The flow effect of the reactant fluid is as follows: Figure 12 As shown.

[0101] like Figure 13 As shown, when heat exchange tubes with left-handed outer wall spiral fins and right-handed outer wall spiral fins are arranged alternately in a heat exchange tube unit, and the spiral fins on the outer walls of the two adjacent alternating heat exchange tubes are mirror-symmetrically distributed in the axial direction, the fluid flowing in this structure passes through this mirror-symmetrical flow channel and has the same residence time. This results in a very uniform temperature distribution of the reaction fluid in the radial direction of the reactor, and consequently, a uniform composition distribution of the reaction fluid in the radial direction of the reactor. Furthermore, the spiral fins guide the fluid to move forward, reducing or even preventing backmixing of liquids with different residence times in the axial direction. The flow effect of the reaction fluid is as follows: Figure 13 As shown.

[0102] The liquid distribution device according to the invention is particularly suitable for fixed-bed reactors, especially for fixed-bed reactors of liquid-solid multiphase catalytic reactions. According to a preferred embodiment, such as... Figure 2As shown, the liquid distribution device includes multiple vertically and uniformly arranged U-shaped heat exchange tubes of the same size, with the inlet and outlet ends of the U-shaped heat exchange tubes spaced in a square pattern. The heat exchange medium flows through the U-shaped heat exchange tubes and is filled with solid catalyst particles on the outside of the tubes to form a catalyst bed. The liquid reactants enter the space containing the solid catalyst particle bed uniformly from top to bottom and undergo a catalytic reaction under the temperature control of the heat exchange medium. During the reaction, the spiral fins on the outer wall of the U-shaped heat exchange tubes prevent the liquid reactants from flowing along the grooves on the outer wall of the U-shaped heat exchange tubes, maintaining a uniform distribution of the liquid reactants in the solid catalyst bed. The spiral fins on the outer wall of the heat exchange tubes rotate in opposite directions to the spiral fins on the inner wall, which enhances the uniformity of heat transfer between the outer and inner walls of the heat exchange tubes, reducing heat transfer resistance and thermal stress. Furthermore, the uniform local temperature distribution on the outer wall of the heat exchange tubes promotes a uniform distribution of the composition of the reaction fluid. In the heat exchange tube unit, heat exchange tubes with left-handed outer spiral fins and heat exchange tubes with right-handed outer spiral fins are arranged alternately, which can significantly improve the uniformity of the composition and temperature distribution of the reaction fluid, thereby improving the performance of the reactor. The outer spiral fins of the adjacent alternating heat exchange tubes are mirror-symmetrically distributed in the axial direction. Due to the mirror-symmetrical flow channels, the converging fluids have the same residence time, thus avoiding the back-mixing effect of fluids with different residence times during convergence.

[0103] Compared with the prior art, the reactor according to the present invention has the following beneficial effects:

[0104] 1) In existing technologies, when liquid reactants flow through a catalyst bed, the gaps between catalyst particles easily create continuous voids on the smooth outer wall of the heat exchange tube. This creates a "short circuit," where the liquid flow tends to concentrate on the outer wall of the heat exchange tube, resulting in channeling. This channeling on the outer wall leads to uneven fluid distribution within the catalyst particle packing area. This invention incorporates helical fins on the outer wall of the heat exchange tube. The helical fins effectively guide the liquid flowing along the outer wall of the heat exchange tube in a radial direction, preventing axial channeling and resulting in a more uniform fluid distribution within the catalyst particle packing area. Simultaneously, it effectively reduces the liquid film thickness on the outer wall of the heat exchange tube, lowering heat transfer resistance and significantly improving heat transfer capacity.

[0105] 2) Through research, the inventors also discovered that as long as the spiral fins protrude from the outer wall of the heat exchange tube, they can guide the liquid reactants to flow radially. However, when the cross-section of the spiral fins is an isosceles triangle, this fluid guiding effect is even better. Further research by the inventors revealed that the fluid guiding effect is closely related to the base and apex angle of the isosceles triangle. The specific range of the ratio h / D of the base h of the isosceles triangle to the diameter D of the heat exchange tube, and the specific range of the apex angle θ used in this invention, can not only effectively avoid channeling on the outer wall of the heat exchange tube and improve the mass and heat transfer capacity of the catalytic reaction, but also avoid generating excessive resistance to the fluid flow through the catalyst bed, thereby reducing the pressure drop of the reactor.

[0106] 3) Through research, the inventors also discovered that if spiral fins are arranged on the inner wall of the heat exchanger tube, with the positions of the inner wall spiral fins not coinciding with those of the outer wall spiral fins, and the rotation directions of the outer wall spiral fins being opposite to those of the inner wall spiral fins, the areas covered by the inner and outer wall spiral fins can be made more symmetrical. In this arrangement, the area formed by the spiral fins and the outer wall of the heat exchanger tube is symmetrically distributed about the central axis of the heat exchanger tube. This symmetry effectively improves the uniformity of heat transfer between the outer and inner walls of the heat exchanger tube by the spiral fins, avoids excessive local temperature differences between the outer and inner walls, reduces thermal stress, and minimizes the adverse effects of deformation caused by thermal stress on the service life of the heat exchanger tube. Simultaneously, the uniform local temperature distribution on the outer wall of the heat exchanger tube can promote the uniform distribution of the reaction fluid.

[0107] 4) Through research, the inventors also discovered that in the heat exchange tube unit, heat exchange tubes with left-handed outer wall spiral fins are arranged alternately with heat exchange tubes with right-handed outer wall spiral fins. This arrangement creates vertical symmetry in the heat exchange tubes. This symmetrical structure guides the flow direction of the reaction fluid. Furthermore, because the spiral fins on adjacent heat exchange tubes rotate in opposite directions, the liquid material experiences alternating flow splitting and converging in the radial direction of the reactor, preventing the liquid material from flowing in a single direction and thus resulting in a more uniform distribution of the fluid in the catalyst particle packing zone. The spiral fins also guide the fluid forward, effectively reducing axial backmixing. The combined effect of these flow characteristics effectively improves the reactor's conversion rate and selectivity. If all the spiral fins on the outer wall of all the heat exchange tubes in the heat exchange tube unit rotate in the same direction, such as all the spiral fins being left-handed or all the spiral fins being right-handed, the consistent rotation direction of the spiral fins on the outer wall of the heat exchange tubes can guide the liquid material flowing along the outer wall of the heat exchange tubes to flow in the radial direction. However, because all the spiral fins rotate in the same direction, the liquid material will tend to flow in one direction, thus affecting the uniform distribution of the fluid in all directions.

[0108] 5) Through research, the inventors also discovered that adjacent alternating heat exchange tubes with left-handed or right-handed helical fins on the outer wall are mirror-symmetrically distributed in the axial direction. The converging fluid flows through the mirror-symmetrical flow channel, thus having the same residence time. Therefore, there is no back-mixing effect when fluids with different residence times converge. If adjacent alternating heat exchange tubes with left-handed or right-handed helical fins on the outer wall are moved relative to each other in the axial direction by a certain distance, and this distance is not an integer multiple of the pitch, this will cause the outer wall helical fins of adjacent heat exchange tubes to be misaligned in the axial direction, and they will not have a mirror-symmetrical relationship relative to the axial direction. At this time, because the converging fluids have different flow paths, their residence times in the reactor are different when converging, which will lead to a back-mixing effect of fluids with different residence times, reducing the conversion rate and selectivity of the reaction.

[0109] 6) When using U-shaped heat exchange tubes in the heat exchange tube unit, the inlet and outlet ends of each U-shaped heat exchange tube are located on the same side and evenly spaced. Since each heat exchange tube uses the same size specifications, the overall structure of the liquid distribution device is more reasonable, and the radial temperature difference in the reactor is controlled to a smaller value. Compared with the prior art where the outlet and inlet of the U-shaped heat exchange tube are symmetrically arranged on both sides of the reactor radially, resulting in a significant temperature difference on both sides of the reactor, this invention can effectively improve the reaction uniformity in the radial direction of the reactor, and avoid the additional thermal stress caused by the large radial temperature difference, which causes thermal deformation of the reactor, thus improving the service life of the reactor.

[0110] 7) The present invention arranges the inlet and outlet ends of two adjacent U-shaped heat exchange tubes in a square, and sets the ratio W / D of the side length W of the square to the diameter D of the heat exchange tube within a certain range. Through experiments, it has been proven that, compared with rectangular or rhomboid arrangements, the square arrangement of the present invention can further improve the flow uniformity of liquid reactants in the catalyst bed.

[0111] 8) The present invention places the screen at the bottom of the catalyst bed below the bottom of the heat exchange tube, which can effectively reduce the risk of catalyst leakage that may be caused by the heat exchange tube passing through the screen and reduce the difficulty of reactor manufacturing and processing.

[0112] 9) This invention proposes a dimensionless metric correlation for calculating heat transfer in a reactor with spiral fins, and the calculation error meets the requirements for engineering use.

[0113] 10) This invention is particularly applicable to fixed-bed reactors for heterogeneous catalytic reactions, i.e., applications where the reactants are all in the liquid phase and the catalyst is a solid catalyst particle; it is especially applicable to the preparation of ethylene glycol by catalytic hydration of ethylene oxide, the preparation of diethylene glycol by catalytic reaction of ethylene oxide and ethylene glycol, the preparation of triethylene glycol by catalytic reaction of ethylene oxide and diethylene glycol, the preparation of propylene glycol by catalytic hydration of propylene oxide, and the preparation of butanediol by catalytic hydration of butane oxide.

[0114] The above description is merely a general overview of the technical solution of the present invention. In order to better understand the technical solution of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention more understandable, several preferred embodiments and comparative examples are listed below, and detailed descriptions are provided in conjunction with the accompanying drawings.

[0115] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0116] In this specification, for ease of description, spatial relative terms such as "below," "under," "down," "above," "over," "upper," etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as "below" or "under" another element or feature would be oriented "above" that element or feature. Thus, the exemplary term "below" can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used in this specification should be interpreted accordingly.

[0117] like Figures 1-13As shown, this invention provides an embodiment of a liquid distribution device in which the heat exchange tube is a U-shaped heat exchange tube. It is mainly applied in multiphase catalytic reaction systems, particularly suitable for catalytic reactions of liquid materials under the action of a solid catalyst bed and at relatively mild reaction temperatures (e.g., around 100°C). Examples include the multiphase catalytic hydration of ethylene oxide to prepare ethylene glycol, the catalytic reaction of ethylene oxide and ethylene glycol to prepare diethylene glycol, the catalytic reaction of ethylene oxide and diethylene glycol to prepare triethylene glycol, the multiphase catalytic hydration of propylene oxide to prepare propylene glycol, or the multiphase catalytic hydration of butane oxide to prepare butanediol. Since these reactions are strongly exothermic, a heat exchange tube unit is required to maintain a relatively stable reaction temperature during the reaction. The reaction temperature is controlled by introducing a heat exchange medium (cooling or heating) into the heat exchange tube of the heat exchange tube unit.

[0118] like Figure 1 As shown, the upper and lower ends of the U-shaped heat exchange tube 1 of this invention are provided with support plates, namely, the upper support plate 11 and the lower support plate 12 of the heat exchange tube. Through the action of the upper and lower support plates, the array formed by the heat exchange tube 1 can be firmly installed in the effective space of the reactor. Screens can be provided at both the upper and lower ends of the catalyst bed, i.e. Figure 1 The reactor includes a top catalyst screen 31 and a bottom catalyst screen 32. This confines the filled catalyst particles within the effective area between the heat exchange tubes 1. Preferably, but not limitingly, the bottom catalyst screen 32 is located below the bottom of the heat exchange tubes 1. Since the catalytic reaction liquid material enters from the top of the reactor, there is no leakage problem with the top screen. To prevent catalyst leakage from the bottom screen, the bottom of the U-shaped heat exchange tube 1 is positioned above the bottom screen 32, i.e., it does not pass through the catalyst screen. This effectively reduces the risk of catalyst leakage caused by the U-shaped heat exchange tube passing through the screen and reduces the difficulty of reactor manufacturing.

[0119] According to one specific embodiment, the liquid distribution device of the present invention includes: a heat exchange tube unit and a catalyst bed. The heat exchange tubes in the heat exchange tube unit are U-shaped heat exchange tubes, and there are multiple of them, arranged vertically. The inlet end of each U-shaped heat exchange tube 1 (i.e., Figure 2 The heat exchange medium inlet 1A and outlet (i.e. Figure 2The heat exchange medium outlets 1B are located on the same side and spaced apart. "The inlet and outlet are on the same side" means that heat exchange tubes of the same specification are arranged regularly, forming an inlet-outlet-inlet-outlet arrangement. This makes the overall structure of the liquid distribution device more rational and minimizes the radial temperature difference within the reactor. Compared to the existing U-shaped heat exchange tubes where the outlet and inlet are arranged on opposite radial sides of the reactor, resulting in a significant temperature difference between the two sides, this invention effectively improves the uniformity of the reaction on the radial cross-section of the reactor, avoids thermal deformation caused by additional thermal stress due to the radial temperature difference, and extends the reactor's service life. The outer wall of the heat exchange tubes is provided with spiral fins 10 (see reference). Figure 3 Furthermore, preferably but not limitingly, the spiral fins can be a raised structure on the outer wall of the heat exchange tube, and the cross-section of the raised structure can be triangular, semi-circular, semi-elliptical, or rectangular, etc. The purpose of providing spiral fins is not only to solve the problem of uneven fluid distribution in the catalyst particle packing area caused by channeling of liquid on the outer wall of the U-shaped tube in the prior art, but also to allow the fluid to flow radially along the reactor, promoting a uniform radial distribution of fluid composition and temperature. A heat exchange medium is introduced into the heat exchange tube 1 to maintain and control the temperature required for the catalytic reaction. The catalyst bed actually occupies the space outside the heat exchange tube in the heat exchange tube unit (see reference). Figure 5 The catalyst loading area 3) is filled with solid catalyst particles; liquid reactants flow in the space to carry out catalytic reactions.

[0120] In existing technologies, when liquid reactants flow in a catalyst bed, the gaps between catalyst particles easily create continuous voids on the smooth outer wall of the heat exchange tube. This causes a "short circuit," meaning the liquid tends to concentrate on the outer wall of the heat exchange tube, resulting in channeling. Since channeling on the outer wall of the U-shaped heat exchange tube leads to uneven fluid distribution within the catalyst, this invention incorporates helical fins on the outer wall of the U-shaped heat exchange tube. These fins effectively guide the liquid flowing along the outer wall of the heat exchange tube in a radial direction, preventing channeling and resulting in a more uniform fluid distribution within the catalyst particle packing area. Simultaneously, by avoiding channeling, the thickness of the liquid film on the outer wall of the heat exchange tube is effectively reduced, lowering heat transfer resistance and thus more effectively improving heat transfer capacity.

[0121] Further as Figure 3 and Figure 4As shown, preferably but not limitingly, the cross-section of the protruding structure of the helical fin 10 can be an isosceles triangle. Through research, the inventors also discovered that as long as the helical fin 10 protrudes from the outer wall of the heat exchange tube 1, it can guide the liquid reactant to flow radially, but the guiding effect is better when the cross-section of the helical fin is an isosceles triangle. Further research revealed that the guiding effect is also closely related to indicators such as the base and apex angle of the isosceles triangle. When the pitch of the helical fin 10 is H and the diameter of the heat exchange tube 1 is D, according to the present invention, the ratio H / D is in the range of 0.2-1.7, preferably 0.3-1.3, for example 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, and 1.2. When half the base of the isosceles triangle is h and half the vertex angle is θ, the ratio h / D is in the range of 0.03-0.1, preferably 0.05-0.09, for example 0.05, 0.06, 0.07 and 0.08, and θ is in the range of 10° to 60°, preferably 20° to 50°, for example 20°, 25°, 30°, 35°, 40°, 45° or 50°. Further research by the inventors has revealed that the range of h / D (the ratio of the base h of the isosceles triangle to the diameter D of the heat exchange tube) and the range of the vertex angle θ used in this invention can not only effectively avoid channeling on the outer wall of the heat exchange tube and improve the mass and heat transfer capacity of the reactor, but also avoid generating significant resistance to the axial flow of the fluid. With h fixed, if θ is too large, the fin structure becomes too smooth, reducing the turbulence effect of the helical fins on the liquid. This limits the radial flow guidance effect, decreasing the helical fins' ability to reduce channeling on the outer wall of the heat exchanger tube and enhance heat transfer. If θ is too small, the helical fin structure becomes too sharp, essentially adding a protruding obstacle in front of the fluid. This creates significant resistance to axial fluid flow, resulting in thick stagnant layers above and below the helical fins, similarly reducing the helical fins' ability to enhance mass transfer. Using helical fins with the aforementioned dimensions can further optimize the above-mentioned technical effects.

[0122] Further as Figure 5 As shown, preferably but not limitingly, adjacent U-shaped heat exchange tubes are arranged in a closely spaced manner (see reference). Figure 5(See left figure) The inlet and outlet ends of the two heat exchange tubes can be arranged in a square, and the spiral fins on the outer walls of adjacent heat exchange tubes rotate in opposite directions. When the side length of the square is W and the diameter of the heat exchange tube is D, the ratio W / D is 1.2-3, preferably 1.5-2.5, and more preferably 1.8-2.4, such as 1.8, 1.9, 2.0, 2.1, 2.2, and 2.3. Through research, the inventors also discovered that the larger the distance between the axes of the two U-shaped heat exchange tubes 1 (i.e., the side length W of the square), the larger the space for packing the catalyst, and the greater the reactor's production capacity. However, the heat transfer area per unit volume of catalyst will decrease. Conversely, the smaller W is, the smaller the space for packing the catalyst, and the smaller the reactor's production capacity. However, the heat transfer area per unit volume of catalyst will increase, which helps remove the heat generated in the reaction, avoids excessive temperature rise, reduces the occurrence of side reactions, and also improves the intrinsic safety characteristics of the reactor. This invention employs a square arrangement, ensuring that the ratio of the side length W of the square to the diameter D of the heat exchange tube is within the aforementioned range. Experiments have shown that, compared to rectangular or rhomboid arrangements, the square arrangement further improves the flow uniformity of the liquid reactants in the catalyst loading area, while effectively reducing the temperature rise of hot spots in the reactor. Furthermore, the use of a specific liquid distribution device in the reactor of this invention significantly increases its production capacity.

[0123] Further as Figures 8 to 10 As shown, spiral fins are also provided on the inner wall of the heat exchange tube. Preferably, but not limitingly, the spiral fins on the outer wall of the heat exchange tube rotate in opposite directions to the spiral fins on the inner wall. Further research has revealed that when the spiral fins on the outer wall of the heat exchange tube rotate in opposite directions to the spiral fins on the inner wall, and when the pitch of the spiral fins on the outer wall of the heat exchange tube is not misaligned, such as... Figure 9 As shown, this arrangement makes the area covered by the spiral fins more symmetrical. The area formed by the spiral fins and the outer wall of the heat exchange tube exhibits a certain symmetry about the central axis of the heat exchange tube. This symmetry effectively improves the uniformity of heat transfer between the outer and inner walls of the heat exchange tube, avoids excessive local temperature differences between the outer and inner walls, reduces thermal stress, and minimizes the adverse effects of thermal stress-induced deformation on the service life of the heat exchange tube. Simultaneously, the uniform local temperature distribution on the outer wall of the heat exchange tube promotes the uniform distribution of the reaction fluid. When the spiral fins on the outer and inner walls of the heat exchange tube rotate in the same direction and have a 1 / 2 pitch misalignment, such as... Figure 10 As shown, the area formed by the spiral fins and the outer wall of the heat exchange tube is not symmetrical about the central axis of the heat exchange tube, and therefore lacks... Figure 9 The advantages of the structure shown.

[0124] Further as Figure 11 and Figure 13As shown, preferably but not limitingly, in the heat exchange tube unit, heat exchange tubes with left-handed outer wall spiral fins and heat exchange tubes with right-handed outer wall spiral fins are arranged alternately, and the adjacent alternating heat exchange tubes are mirror-symmetrically distributed in the axial direction. Further research by the inventors revealed that this arrangement gives the heat exchange tubes a certain symmetry in the axial direction of the reactor. This symmetrical structure plays a good role in the uniform distribution of the reaction fluid in the radial direction. Furthermore, when the rotation directions of the outer wall spiral fins of adjacent heat exchange tubes are opposite, this allows the liquid material flowing through the spiral fins to produce an alternating flow effect of diversion and convergence in the radial direction of the reactor. This avoids the liquid material deflection in a single direction caused by all the outer wall spiral fins of the heat exchange tubes rotating in the same direction. When liquid materials flow in a reactor with a structure in which heat exchange tubes with left-handed outer wall spiral fins and heat exchange tubes with right-handed outer wall spiral fins are arranged alternately, the residence time of the fluid at the convergence is the same, and there will be no low feed conversion rate and low selectivity due to the backmixing effect of fluids with different residence times.

[0125] The liquid distribution device of the present invention is particularly suitable for heterogeneous catalytic reactions. The heterogeneous catalytic reactor can be selected from reactors for preparing ethylene glycol via catalytic hydration, reactors for preparing diethylene glycol via the catalytic reaction of ethylene oxide and ethylene glycol, reactors for preparing triethylene glycol via the catalytic reaction of ethylene oxide and diethylene glycol, reactors for preparing propylene glycol via catalytic hydration, and reactors for preparing butanediol via catalytic hydration; the liquid reactants can be liquid ethylene oxide and liquid water, liquid ethylene oxide and liquid ethylene glycol, liquid ethylene oxide and liquid diethylene glycol, liquid propylene oxide and liquid water, or liquid butane oxide and liquid water; the solid catalyst used can be selected from resins.

[0126] According to a preferred embodiment, such as Figure 1 and 2 As shown, the present invention also provides a fixed-bed reactor (fixed bed not shown), which includes the aforementioned liquid distribution device. The heat exchange medium inlet manifold 13 and heat exchange medium outlet manifold 14 of the fixed-bed reactor are both located at the top of the reactor, positioned higher than the liquid distributor. The heat exchange medium inlets 1A of all U-shaped heat exchange tubes are connected to the heat exchange medium inlet manifold 13, and the heat exchange medium outlets 1B of all U-shaped heat exchange tubes are connected to the heat exchange medium outlet manifold 14. Further, the liquid distributor 2 is located above the reactor, and the flow direction of the reaction fluid is parallel to the reactor axis. Further reference Figure 6 The liquid outlet 21 of the liquid distributor 2 is preferably located in the middle region above the solid particle loading unit, which ensures that the downward liquid material is evenly distributed in the catalyst loading area. The opening ratio of the distributor outlet can be 2‰-75‰.

[0127] This invention also provides a reaction method using the aforementioned fixed-bed reactor, wherein the fixed-bed reactor is suitable for multiphase catalytic reactions and includes multiple vertically uniformly arranged U-shaped heat exchange tubes of the same size, wherein the inlet and outlet ends of the U-shaped heat exchange tubes are spaced apart; both the inner and outer walls of the U-shaped heat exchange tubes are provided with spiral fins; a heat exchange medium is introduced into the U-shaped heat exchange tubes and solid catalyst particles are filled on the outside of the U-shaped heat exchange tubes to form a solid catalyst bed; the liquid reactants that enter the solid catalyst bed uniformly from top to bottom undergo catalytic reactions on the catalyst surface under the temperature control of the heat exchange medium; during the reaction, the spiral fins on the outer wall of the U-shaped heat exchange tubes prevent channeling on the outer wall to maintain a uniform distribution of the liquid phase in the solid catalyst bed. The spiral fins on the outer and inner walls of the heat exchange tubes rotate in opposite directions. The area formed by the spiral fins and the outer wall of the heat exchange tube is symmetrical about the central axis of the tube. This symmetry effectively improves the uniformity of heat transfer between the outer and inner walls of the heat exchange tube, preventing excessive local temperature differences and reducing thermal stress. By arranging heat exchange tubes with left-handed and right-handed spiral fins adjacent to each other in the heat exchange tube unit, and ensuring that these alternating tubes are mirror-symmetrically distributed axially, the liquid flowing through the spiral fins is separated and converged. This ensures uniform radial distribution of the liquid in the solid catalyst bed. Simultaneously, the guiding effect of the spiral fins enhances radial flow while reducing axial backmixing. These effects improve feed conversion rate and reaction selectivity. Preferably, but not limitingly, this reaction method can be used to prepare ethylene glycol via catalytic hydration of ethylene oxide, to prepare diethylene glycol via catalytic reaction of ethylene oxide and ethylene glycol, to prepare triethylene glycol via catalytic reaction of ethylene oxide and diethylene glycol, to prepare propylene glycol via catalytic hydration of propylene oxide, and to prepare butanediol via catalytic hydration of butane oxide. In the preparation of ethylene glycol, liquid reactants are liquid ethylene oxide and liquid water, and the solid catalyst is selected from resins; the reaction temperature is 85–150°C, the pressure is 1.0–1.8 MPa, and the reaction time is 0.5–5 h. -1 Under certain space velocity conditions, the liquid reactants in the fixed-bed reactor of the present invention come into contact with and react with a solid catalyst packed on the outside of the heat exchange tubes to generate ethylene glycol with high selectivity and high yield.

[0128] Example

[0129] The following embodiments are used to illustrate the preferred technical solutions of the present invention, and therefore are not intended to limit the scope of protection of the present invention; in these embodiments, the feed conversion rate is calculated by measuring the changes in ethylene oxide concentration at the reactor inlet and outlet; the concentration of ethylene oxide is measured by gas chromatography; the selectivity of ethylene glycol is calculated by measuring the ethylene glycol concentration at the reactor outlet; and the hot spot temperature rise of the reactor is measured as follows: Figure 5 A sleeve is inserted into the central catalyst bed shown in the diagram. A thermocouple is inserted into the sleeve and moved up and down. The maximum temperature rise of this hot spot usually occurs at the top of the catalyst bed, approximately 20% of the catalyst bed height from the top surface. However, the location of the hot spot can vary with process conditions such as liquid hourly space velocity and feed ratio. The reactor pressure drop is the pressure difference between the inlet and outlet of the reaction fluid, measured using a differential pressure gauge. Other parameters are measured according to conventional methods in the art.

[0130] Example 1

[0131] This embodiment uses a method such as Figure 1 The fixed-bed reactor shown is for the multiphase catalytic hydration of ethylene glycol. The reactor diameter is 500 mm and the fixed bed height is 1300 mm. It contains multiple U-shaped heat exchange tubes with a diameter D of 15 mm and a wall thickness of 1 mm. The outer wall of each U-shaped heat exchange tube has helical fins with an isosceles triangular cross-section, and the inner wall also has helical fins with an isosceles triangular cross-section. Some of the outer wall helical fins are left-handed, while others are right-handed. Both the inner and outer wall helical fins are single-threaded with n = 1 thread. The inner and outer wall helical fins of the same heat exchange tube rotate in opposite directions and have the same pitch. Within a heat exchange tube unit, heat exchange tubes with left-handed outer wall helical fins are arranged alternately with those with right-handed outer wall helical fins, as shown below. Figure 13 As shown, two adjacent U-shaped heat exchange tubes are arranged in a mirror-symmetrical configuration. The outer wall spiral fins and the inner wall spiral fins of the heat exchange tubes have the same cross-section, where the ratio of h to the diameter D of the U-shaped heat exchange tube (h / D) is 0.08, and θ is 30°. The ratio of pitch H to D (H / D) is 0.5, and its corresponding helix angle is... The angle is 14°. Two U-shaped heat exchange tubes are arranged in a square pattern. The ratio of the distance W between the axes of two adjacent heat exchange tubes to the diameter D of the U-shaped heat exchange tube, W / D, is 2. The liquid distributor has an opening ratio of 40‰. The catalyst unit contains spherical resin catalyst particles with a sphericity of 0.85 and a number-average diameter d such that the ratio d / D is approximately 0.1. The liquid reactants pass through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1 h. -1A liquid hourly space velocity (LHSV) feedstock, wherein the molar ratio of liquid water to liquid ethylene oxide is 5:1, is fed into the reactor to synthesize ethylene glycol via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this fixed-bed reactor, the feedstock conversion rate is greater than 99.9%, the ethylene glycol selectivity is greater than 99.9%, and the reactor hotspot temperature rise is 3.5°C.

[0132] Example 2

[0133] This embodiment uses a fixed-bed reactor and similar operating parameters as Example 1, but differs in that θ is 45°. The liquid material is fed through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1 Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.7%, and the hot spot temperature rise of the reactor is 3.7°C.

[0134] Example 3

[0135] This embodiment uses a fixed-bed reactor and similar operating parameters as Example 1, but differs in that the ratio of h to the diameter D of the U-shaped heat exchange tube, h / D, is 0.04. The liquid material is introduced through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1 Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.5%, and the hot spot temperature rise of the reactor is 3.8°C.

[0136] Example 4

[0137] This embodiment uses a fixed-bed reactor and similar operating parameters as Embodiment 1, but differs in that the ratio W / D of the distance between the centers of two adjacent heat exchange tubes to the diameter D of the U-shaped heat exchange tube is 2.5. The liquid material passes through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h... -1 Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.0%, and the reactor hotspot temperature rise is 4.2°C.

[0138] Example 5

[0139] This embodiment uses a fixed-bed reactor and similar operating parameters as Example 1, but differs in that the ratio of pitch H to D, H / D, is 1. The liquid material is fed through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1 Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.2%, and the reactor hotspot temperature rise is 4.0 °C.

[0140] Example 6

[0141] This embodiment uses a fixed-bed reactor and similar operating parameters as Embodiment 1, but differs in that the ratio of the screw pitch H to D is H / D = 1 and the ratio of the distance W between the centers of two adjacent heat exchange tubes to the diameter D of the U-shaped heat exchange tube is W / D = 1.7. The liquid material passes through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h... -1 Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.8%, and the reactor hotspot temperature rise is 3.6°C.

[0142] Example 7

[0143] This embodiment uses a fixed-bed reactor and similar operating parameters as Embodiment 1, but differs in that the ratio of the screw pitch H to D, H / D, is 1.5, the ratio of the distance W between the centers of two adjacent heat exchange tubes to the diameter D of the U-shaped heat exchange tube, W / D, is 1.7, and θ is 20°. The liquid material passes through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h... -1 Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.2%, and the reactor hotspot temperature rise is 4.1°C.

[0144] Example 8

[0145] This embodiment uses a fixed-bed reactor and similar operating parameters as Embodiment 1, but differs in that the ratio of the screw pitch H to D (H / D) is 1, the ratio of the distance W between the centers of two adjacent heat exchange tubes to the diameter D of the U-shaped heat exchange tube (W / D) is 2.2, the ratio of h to the diameter D of the U-shaped heat exchange tube (h / D) is 0.1, and θ is 20°. The liquid material passes through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h... -1 Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 98.9%, and the reactor hotspot temperature rise is 4.5°C.

[0146] Example 9

[0147] This embodiment uses a fixed-bed reactor and similar operating parameters as Embodiment 1, but differs in that the spiral fins on the inner and outer walls of the same heat exchange tube rotate in the same direction and have equal pitch. The liquid material is fed through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1 Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.0%, and the hot spot temperature rise of the reactor is 4.2°C.

[0148] A comparison of Examples 9 and 1 reveals that, since the inner wall spiral fins of the heat exchange tubes in the reactor used in Example 1 rotate in the opposite direction to the outer wall spiral fins, the feed conversion rate and ethylene glycol selectivity of the reactor in Example 1 are both higher than the corresponding parameters in Example 9, and the hot spot temperature of the reactor in Example 1 is also lower. This demonstrates that the rotation direction of the inner wall spiral fins and the rotation direction of the outer wall spiral fins of the heat exchange tubes in the reactor have a synergistic effect on the reactor's performance.

[0149] Comparative Example 1

[0150] This comparative example uses a fixed-bed reactor and similar operating parameters as Example 1, but differs in that the spiral fins on the outer wall of the straight sections of all U-shaped heat exchange tubes rotate in a right-handed direction, and any two adjacent U-shaped heat exchange tubes are arranged as follows: Figure 11 The arrangement is as shown; the rotation direction of the spiral fins on the inner wall of the heat exchange tube is opposite to that of the spiral fins on the outer wall of the heat exchange tube. The liquid reactants pass through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements showed that the feed conversion rate for the ethylene glycol synthesis reaction in this reactor was 98.2%, the ethylene glycol selectivity was 98.3%, and the hot spot temperature rise of the reactor was 4.9 °C.

[0151] In Comparative Example 1, the arrangement of the spiral fins on the outer wall is not alternating between left and right spirals, which worsens the flow pattern. Although the hot spot temperature increases, the conversion rate decreases significantly.

[0152] Comparative Example 2

[0153] This comparative example uses a fixed-bed reactor and similar operating parameters as Example 1, but differs in that the spiral fins on the outer wall of the straight section of the U-shaped heat exchange tubes rotate entirely to the left, and adjacent U-shaped heat exchange tubes are arranged as follows: Figure 11 The arrangement is as shown. The rotation direction of the inner wall spiral fins of the heat exchange tubes is opposite to that of the outer wall spiral fins. The liquid reactants pass through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1 Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements showed that the feed conversion rate was 98.2%, the ethylene glycol selectivity was 98.2%, and the hot spot temperature rise in the reactor was 4.9°C for the ethylene glycol synthesis reaction carried out in this reactor.

[0154] Comparative Example 3

[0155] This comparative example uses a fixed-bed reactor and similar operating parameters as Example 1, but differs in that the spiral fins on the outer wall of the straight section of the U-shaped heat exchange tubes rotate entirely to the left, and adjacent U-shaped heat exchange tubes are arranged as follows: Figure 11 The arrangement is as shown. The inner wall spiral fins of the heat exchange tube rotate in the same direction as the outer wall spiral fins, and the pitch of the inner and outer wall spiral fins is equal. The liquid reactants pass through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1 Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements showed that the feed conversion rate was 98.9%, the ethylene glycol selectivity was 97.6%, and the hot spot temperature rise in the reactor was 5.7°C for the ethylene glycol synthesis reaction carried out in this reactor.

[0156] Comparative Example 4

[0157] This comparative example uses a fixed-bed reactor and similar operating parameters as Example 1, but differs in that the spiral fins on the outer wall of the straight section of the U-shaped heat exchange tubes rotate in a right-handed direction, and adjacent U-shaped heat exchange tubes are arranged as follows: Figure 11 The arrangement is as shown. The rotation direction of the inner wall spiral fins of the heat exchange tubes is the same as that of the outer wall spiral fins, and the pitch of the inner and outer wall spiral fins is equal. The liquid reactants pass through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1 Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements showed that the feed conversion rate was 99.0%, the ethylene glycol selectivity was 97.6%, and the hot spot temperature rise in the reactor was 5.7°C for the ethylene glycol synthesis reaction carried out in this reactor.

[0158] Comparative Example 5

[0159] This comparative example uses a fixed-bed reactor and similar operating parameters as Example 1, but differs in that the spiral fins on the outer wall of the straight section of the U-shaped heat exchange tubes rotate entirely to the left, and adjacent U-shaped heat exchange tubes are arranged as follows: Figure 11 The arrangement is as shown. There are no spiral fins on the inner wall of the heat exchange tubes. The liquid reactants pass through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1h. -1 Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that the feed conversion rate for the ethylene glycol synthesis reaction in this reactor is greater than 99.9%, the ethylene glycol selectivity is 94.9%, and the hot spot temperature rise of the reactor is 9.7°C.

[0160] By comparing the experimental results of Comparative Examples 4 and 5 with those of Example 1, it can be seen that in the heat exchange tube unit, the alternating arrangement of heat exchange tubes with left-handed outer wall spiral fins and heat exchange tubes with right-handed outer wall spiral fins can make the fluid distribution in the catalyst particle packing zone more uniform, significantly improve the feed conversion rate and selectivity, and significantly reduce the hot spot temperature of the reactor.

[0161] Comparative Example 6

[0162] This comparative example uses a fixed-bed reactor and similar operating parameters to Example 1, but differs in that there are no spiral fins on the outer and inner walls of the U-shaped heat exchange tubes. The liquid reactants are distributed through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1 h / min. -1Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that the feed conversion rate for the ethylene glycol synthesis reaction in this reactor is greater than 99.9%, the ethylene glycol selectivity is 90.2%, and the hot spot temperature rise of the reactor is 19.8°C.

[0163] Comparative Examples 1 to 6 showed that as the hot spot temperature increased, the reaction conversion rate increased, but the selectivity decreased. The results of the above examples and comparative examples are listed in Table 1 below.

[0164] Table 1

[0165]

[0166] Example 10

[0167] This comparative example uses a fixed-bed reactor and similar operating parameters to Example 1, but differs in that the spiral fins on the outer wall of the straight sections of adjacent U-shaped heat exchange tubes are axially offset by 1 / 4 pitch. The liquid reactants are fed through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1 h. -1 Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is 99.5%, the ethylene glycol selectivity is 99.6%, and the reactor hotspot temperature rise is 3.5°C.

[0168] Example 11

[0169] This comparative example uses a fixed-bed reactor and similar operating parameters to Example 1, but differs in that the spiral fins on the outer wall of the straight sections of adjacent U-shaped heat exchange tubes are axially offset by 1 / 2 pitch. The liquid reactants are fed through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1 h. -1 Liquid hourly space velocity (LIHSV) is fed into the reactor, with a liquid water to liquid ethylene oxide molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is 99.1%, the ethylene glycol selectivity is 99.3%, and the reactor hotspot temperature rise is 3.5°C.

[0170] The axial misalignment of the spiral fins on the outer wall of the straight sections of two adjacent U-shaped heat exchange tubes does not affect the heat transfer performance. The hot spot temperature rise is the same in Examples 1, 10, and 11. However, axial misalignment will cause back mixing, reducing the conversion rate and selectivity of the reaction. The greater the axial misalignment, the greater the reduction in conversion rate and selectivity. The results of the above examples are listed in Table 2 below.

[0171] Table 2

[0172]

[0173] Example 12

[0174] This embodiment uses a fixed-bed reactor and similar operating parameters as Embodiment 1, but differs in that the cross-section of the spiral fins on the outer wall of the heat exchange tubes is semi-circular, the ratio of the semi-circular radius to the diameter D of the U-shaped heat exchange tube is 0.08, the ratio of the pitch H to D is H / D, and the ratio of the distance W between the centers of two adjacent heat exchange tubes to the diameter D of the U-shaped heat exchange tube is W / D, which is 1.7. The liquid material passes through a liquid distributor with an opening ratio of 40‰ at a rate of 0.9h... -1 Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.0%, and the hot spot temperature rise of the reactor is 4.3°C.

[0175] Example 13

[0176] This embodiment uses a fixed-bed reactor and similar operating parameters as Embodiment 1, but differs in that the cross-section of the spiral fins on the outer wall of the heat exchange tube is rectangular, with the longer side closest to the wall being the longer side. The ratio of the longer side to the diameter D of the U-shaped heat exchange tube is 0.16, the aspect ratio of the rectangle is 2, the ratio of the pitch H to D is H / D is 1, and the ratio of the distance W between the centers of two adjacent heat exchange tubes to the diameter D of the U-shaped heat exchange tube is W / D is 1.7. The liquid material passes through a liquid distributor with an opening ratio of 40‰ at a rate of 0.9h... -1 Liquid hourly space velocity (LIHSV) is fed into a reactor containing liquid water and liquid ethylene oxide in a molar ratio of 5:1, where ethylene glycol is synthesized via a catalytic hydration reaction. Measurements show that for the ethylene glycol synthesis reaction carried out in this reactor, the feed conversion rate is greater than 99.9%, the ethylene glycol selectivity is 99.1%, and the hot spot temperature rise of the reactor is 4.2 °C.

[0177] Examples 12 and 13 above also confirm that when the cross-section of the outer wall spiral fins of the heat exchange tube is rectangular and semi-circular, as long as the outer wall spiral fins of adjacent heat exchange tubes are alternating between left-handed and right-handed spirals, the obtained reactor can also achieve high conversion rate and high selectivity for the reaction occurring therein.

[0178] The foregoing description of embodiments of the present invention is intended to illustrate the purpose and advantages of the technical solutions of the present invention. These descriptions are not intended to limit the present invention to the specific forms disclosed, and it is obvious that many changes and variations can be made by those skilled in the art based on the above teachings. The embodiments were chosen and described to illustrate the practical application of the technical solutions of the present invention and their advantages over the prior art, thereby enabling those skilled in the art to implement and utilize various different embodiments of the present invention and to make various different choices and changes. Any simple modifications, equivalent changes, and alterations made to the above embodiments should fall within the protection scope of the present invention.

Claims

1. A liquid distribution device for a reactor, characterized in that The liquid distribution device comprises: The heat exchange tube unit comprises a plurality of vertically arranged heat exchange tubes, at least a part, preferably all of the outer wall of the heat exchange tubes is provided with left-handed or right-handed helical fins, and wherein the rotation direction of the helical fins on the outer wall of at least a part of the heat exchange tubes is opposite to that of the helical fins on the outer wall of the heat exchange tubes arranged adjacent thereto, preferably the rotation direction of the helical fins on the outer wall of all of the heat exchange tubes is opposite to that of the helical fins on the outer wall of the heat exchange tubes arranged adjacent thereto; and a heat exchange medium flows in the heat exchange tubes, while a liquid reaction material flows outside the heat exchange tubes in a direction almost parallel to the axial direction of the heat exchange tubes; An optional solid particle loading unit comprising solid particles filled in the space between the heat exchange tubes.

2. The liquid distribution device of claim 1, wherein, The heat exchange tubes are selected from straight tube heat exchange tubes or U-shaped heat exchange tubes, wherein the rotation direction of the helical fins on the outer wall of the straight tube portions of the U-shaped heat exchange tubes can be the same or different, and wherein the inlet end and the outlet end of each U-shaped heat exchange tube are arranged at intervals, preferably both the upper and lower ends of the heat exchange tubes are provided with support plates.

3. The liquid distribution device of any one of claims 1-2, wherein, The inner wall of at least a part, preferably all of the heat exchange tubes is provided with helical fins, wherein the rotation direction of the helical fins on the outer wall of the heat exchange tubes is the same as or opposite to that of the helical fins on the inner wall of the heat exchange tubes, preferably opposite.

4. The liquid distribution device of claim 3, wherein, The helical fins on the outer wall and / or the inner wall of the heat exchange tubes are protruding structures on the outer wall and / or the inner wall of the heat exchange tubes, wherein the cross-sectional shape of the protruding structures is triangular, semicircular, semi-elliptical or rectangular, preferably isosceles triangular.

5. The liquid distribution device of claim 4, wherein, The liquid distribution device is used in a fixed bed reactor for carrying out liquid-solid reactions, and the liquid distribution device comprises a solid particle loading unit selected from a solid packing bed or a solid catalyst bed, which comprises a packing or catalyst in particle form filled in the space between any heat exchange tubes.

6. The liquid distribution device of claim 1 or 2, wherein, The liquid distribution device comprises a solid particle loading unit, the size of each heat exchange tube is the same and uniformly arranged, the inlet end and the outlet end of two adjacent U-shaped heat exchange tubes or the inlet end of every two adjacent four straight tube heat exchange tubes are arranged in a square, the side length of the square is W, the diameter of the heat exchange tube is D, the cross section of the helical fin on the outer wall of the heat exchange tube is triangular, half of the base length of the triangle is h, half of the top angle of the triangle is θ, the pitch of the helical fin is H and the diameter of the heat exchange tube is D, and the fixed bed height is l, at this time the heat transfer coefficient of the reactor comprising the liquid distribution device and the structural parameters of the helical fin and the arrangement structural parameters of the heat exchange tube satisfy the following relationship (1): In the above formula, D e represents the characteristic dimension in m: Re represents the Reynolds number: and such that 0.6 < Re < 50; a represents the heat transfer coefficient in W / (m 2 ·K) of the reactor comprising the liquid distribution device, and such that a > 30 W / (m 2 ·K); p represents the density in kg / m 3 of the reaction liquid, and m represents the viscosity in Pa·s of the reaction liquid; u represents the flow rate in m / s of the reaction liquid, which is calculated as follows: from the predetermined liquid space velocity and the volume of catalyst packed in the reactor comprising the liquid distribution device, the total volumetric flow rate of the feed can be determined, from which the volumetric flow rate of the feed per individual repeating unit is calculated, and then the volumetric flow rate of the feed per individual repeating unit is divided by the cross-sectional area of the individual repeating unit , i.e. the flow rate u; W, D, H, h and l are all in units of m; Q is in radians; Pr represents the property constant, where c p represents the specific heat capacity at constant pressure of the liquid in J / (kg·℃), and l represents the thermal conductivity of the liquid in W / (m·K); M and N are dimensionless constants, N = 0.37 when the rotation directions of the outer wall spiral fins of all the heat exchange tubes are the same, N = 0.88 when the rotation directions of the outer wall spiral fins of all the heat exchange tubes are opposite to those of the heat exchange tubes adjacent thereto, M = 1.18 when the rotation direction of the outer wall spiral fins of the heat exchange tubes is opposite to that of the inner wall spiral fins of the heat exchange tubes, and M = 1 when the rotation directions are the same.

7. The liquid distribution device of any one of claims 1-6, wherein, The size of each heat exchange tube is the same and uniformly arranged, the inlet end and the outlet end of two adjacent U-shaped heat exchange tubes or the inlet end of every two adjacent four straight tube heat exchange tubes are arranged in a square, when the side length of the square is W in m, the diameter of the heat exchange tube is D in m, W / D = 1.2-3, preferably 1.5-2.5, more preferably 1.8-2.

4.

8. The liquid distribution device of any one of claims 1-7, wherein, The pitch of the outer wall spiral fins of the heat exchange tubes is equal, and when the pitch of the spiral fins in meters is H and the diameter of the heat exchange tubes in meters is D, the ratio H / D is 0.2-1.7, preferably 0.3-1.

3.

9. The liquid distribution device of any one of claims 4-8, wherein, When the cross-sectional shape of the protruding structure is triangular, half of the base of the triangle in meters is h and half of the top angle is θ, and the ratio h / D is 0.03-0.1, preferably 0.05-0.09, and θ is 10° to 60°, preferably 20° to 50°.

10. The liquid distribution device of any one of claims 1-9, wherein, The liquid distribution device is used in a fixed bed reactor for carrying out a liquid-solid reaction, and the liquid distribution device at this time comprises a solid particle packing unit selected from a solid packing bed or a solid catalyst bed, which includes a packing or catalyst in particulate form filled in the space between any two adjacent heat exchange tubes.

11. The liquid distribution device of any one of claims 1-10, wherein, The liquid distribution device further comprises a liquid distributor located above or below the heat exchange tube unit, and the opening rate of the liquid outlet holes of the liquid distributor is 2‰-75‰.

12. The liquid distribution device of any one of claims 1-11, wherein, The outer wall spiral fins of all the heat exchange tubes are axially misaligned by at most 1 / 3 of the pitch, preferably at most 1 / 4 of the pitch, with the outer wall spiral fins of the heat exchange tubes arranged adjacent thereto, and preferably, the outer wall spiral fins of all the heat exchange tubes are axially arranged in mirror symmetry with the outer wall spiral fins of the heat exchange tubes arranged adjacent thereto.

13. The liquid distribution device of any one of claims 1-12, wherein, The catalyst bed is provided with a screen at both the upper and lower ends, and the screen at the lower end is located below the bottom of the heat exchange tube.

14. The liquid distribution device of any one of claims 1-13, wherein, The liquid distribution device is used in a fixed bed reactor for carrying out a liquid-solid reaction, and the fixed bed reactor is used for catalytic hydration to prepare ethylene glycol, catalytic reaction to prepare diethylene glycol, catalytic reaction to prepare triethylene glycol, catalytic hydration to prepare propylene glycol, or catalytic hydration to prepare butylene glycol, wherein the liquid reaction material is liquid ethylene oxide and liquid water, liquid ethylene oxide and liquid ethylene glycol, liquid ethylene oxide and liquid diethylene glycol, liquid propylene oxide and liquid water, or liquid butylene oxide and liquid water, respectively, and preferably, the solid catalyst used is selected from a resin.

15. A method of performing a heterogeneous catalytic reaction, characterized by, A fixed bed reactor comprising the liquid distribution device according to any one of claims 1-14 is used.

16. The method of claim 15, wherein, The method is used to prepare ethylene glycol by catalytic hydration of ethylene oxide, diethylene glycol by catalytic reaction of ethylene oxide and ethylene glycol, triethylene glycol by catalytic reaction of ethylene oxide and diethylene glycol, propylene glycol by catalytic hydration of propylene oxide, or butylene glycol by catalytic hydration of butylene oxide.

17. The method of claim 16, wherein, The liquid reaction material is liquid ethylene oxide and liquid water, and a resin is used as the solid catalyst.

18. The method of claim 17, wherein, The liquid reaction mass is passed through a fixed bed reactor at a reaction temperature of 85 to 150°C, a pressure of 1.0 to 1.8 MPa, a liquid hourly space velocity of 0.5 to 5 h -1 under conditions in which the liquid reaction mass is reacted in contact with a solid catalyst packed between heat exchange tubes to produce ethylene glycol.

19. A method for improving temperature distribution in a fixed bed reactor, wherein the liquid distribution device according to any one of claims 1-14 is used in the fixed bed reactor.

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