Fixed bed reactor comprising liquid distribution apparatus and method for performing multi-phase catalytic reaction by using reactor

Abstract

A reactor comprising a liquid distribution apparatus and a method for performing multi-phase catalytic reaction by using said reactor. The reactor comprises: a heat exchange tube unit, comprising a plurality of vertically arranged heat exchange tubes (1). Outer walls of at least part of the heat exchange tubes (1) are provided with left-handed or right-handed spiral fins (10), and the spiral directions of outer-wall spiral fins (10) of at least part of the heat exchange tubes (1) are the reverse of the spiral directions of outer-wall spiral fins (10) of heat exchange tubes (1) arranged adjacent thereto. A heat exchange medium flows within the heat exchange tubes (1), and a liquid reaction material flows outside of the heat exchange tubes (1) in a direction almost parallel to the axial direction of the heat exchange tubes (1).

Description

Fixed bed reactor comprising a liquid distribution device and method for performing heterogeneous catalytic reactions using such a reactor Technical Field

[0001] The present invention relates to the technical field of heterogeneous catalytic reactions, and in particular to a reactor comprising a liquid distribution device and a method for performing heterogeneous catalytic reactions using the reactor. Background Art

[0002] Heterogeneous catalytic reactions are chemical reactions in which one or more reactants react at an interface, such as on a solid catalyst surface. Heterogeneous catalytic reactions are typically carried out in fixed-bed reactors, fluidized-bed reactors, moving-bed reactors, fed-bed reactors, and rotating-bed reactors.

[0003] Fixed-bed reactors are widely used in the chemical industry due to their small size, high reaction rates, and ease of control. Shell-and-tube fixed-bed reactors are commonly used in highly exothermic reaction systems. Similar in structure to fixed-tube-sheet heat exchangers, the tube side forms the reaction zone, with the catalyst loaded within the tubes. As the material passes through the catalyst within the tubes, a reaction occurs, while the shell side is filled with heat transfer medium, forming a reaction and heat exchange system. Common applications for shell-and-tube fixed-bed reactors include methanol synthesis towers, ethylene oxide reactors, acrylic acid reactors, and coal-to-ethanol reactors.

[0004] Sasol and Shell have successively developed fixed-bed reactors for industrial use in Fischer-Tropsch synthesis. The reactors are filled with catalyst-filled tubes, with water between the tubes generating steam to dissipate heat out of the reactor. The Fischer-Tropsch reaction is highly exothermic, and fixed-bed reactors exhibit temperature nonuniformity both radially and axially within the tubes. The current method for maintaining uniform bed temperature is to reduce the diameter of the reactor tubes. However, in smaller tube diameters, synthesis gas is more susceptible to carbon deposition on the catalyst surface, leading to localized overheating and catalyst cracking and deactivation.

[0005] In this field, improvements to the shell-and-tube fixed-bed reactor are multifaceted, including the development from the traditional fixed shell-and-tube structure to the bayonet tube type, self-cooling type, branch tube bundle type, plate type, winding tube type and other structures, so as to improve the reactor space utilization rate, reduce the energy consumption of the device and the difficulty of reactor manufacturing, and improve the production capacity of a single reactor while ensuring the heat exchange effect.

[0006] However, heat transfer in fixed-bed reactors used in highly exothermic reaction systems is a technical challenge. Researchers have improved the heat transfer efficiency of fixed-bed reactors by changing the shape of the packing and optimizing fluid dynamics.

[0007] CN101480595B proposes the use of pin-fin heat exchange tubes to achieve both flow field regulation and heat transfer enhancement. Pin-fins reduce liquid velocity and axial back-mixing. Furthermore, they 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 the reduced liquid velocity. However, while this approach addresses both heat exchange and back-mixing, the collision between the pin-fins and catalyst particles can cause catalyst wear, which can reduce catalyst performance, 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. Liquid-solid reaction systems have lower liquid hourly space velocities than gas-solid reaction systems. Due to the significant differences in density and viscosity between liquids and gases, the fluid motion distribution patterns in liquid-solid systems differ significantly from those in gas-solid systems. This is particularly true for highly exothermic liquid-solid reaction systems, as conventional fixed-bed reactors struggle to efficiently remove heat from the reactor, typically requiring only relatively low reaction rates.

[0009] Heat exchange tubes with spiral fins are generally used for fluids with high flow rates, such as gas-solid reaction systems. This is because heat exchange tubes with spiral fins or threads disturb the high-speed flow of fluid, continuously destroying the fluid boundary layer, effectively improving the heat transfer film coefficient and producing a good enhanced heat transfer effect. For example, Chinese patent application CN 209222077 discloses a heat transfer system for a Fischer-Tropsch synthesis reactor, which includes a heat exchange element and a steam drum, wherein the heat exchange element is disposed within the reactor; wherein the heat exchange tubes can take three structural forms, the most commonly used being smooth metal tubes, and metal tubes with pin fins and / or metal tubes with external thread grooves can also be used; 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 using a heterogeneous catalytic hydration process in a fixed-bed reactor. For example, Chinese patent application CN101306984A discloses a fixed-bed reactor for the catalytic hydration of ethylene oxide to produce ethylene glycol. By loading the catalyst onto the outside of a U-shaped tube array, the problem of catalyst expansion after loading can be addressed to a certain extent, as well as heat transfer optimization. However, the U-shaped tubes used are prone to channeling the reaction liquid outside the tubes along the tube walls during flow, resulting in uneven distribution of the liquid radially along the fixed bed. Disc-shaped redistributors are limited in their ability to address this channeling phenomenon. This channeling of the reaction liquid can affect feedstock conversion and selectivity. Furthermore, the channeling effect results in a thicker liquid film outside the U-shaped tubes, increasing heat transfer resistance and reducing the heat transfer capacity of the U-shaped tubes. Furthermore, the U-shaped tubes are of different specifications, with the inlet and outlet ends located on opposite sides of the reactor. This distribution of the U-shaped tubes can lead to temperature differences in the reactor bed, which also affects the reaction conversion and yield. Thermal stress caused by temperature differences can also shorten the life of the reactor.

[0011] In order to overcome the above problems in the prior art, there is an urgent need for a liquid distribution device that can effectively avoid the occurrence of channeling and make the reaction liquid in the catalyst particle loading area more evenly distributed, and a fixed bed reactor including the liquid distribution device.

[0012] Summary of the Invention

[0013] After research, the inventors surprisingly discovered that the above-mentioned problems can be overcome by using a reactor containing a specific liquid distribution device, wherein the liquid distribution device includes a plurality of heat exchange tubes with spiral fins arranged in a specific arrangement. The inventors found that when this reactor is used in a liquid-solid reaction system with a reaction liquid having a low flow rate, the liquid distribution device has a strong promoting effect on the liquid-solid reaction, significantly improving the reaction selectivity. Without being bound by a particular theory, the inventors believe that when this specific arrangement of heat exchange tubes with spiral fins is used in a liquid-solid reaction system with a reaction liquid having a low flow rate, the main function of the spiral fins is to change the flow direction of the fluid, promote the flow of the fluid in the radial direction, so that fluids with almost equal residence time are divided and merged in the radial direction, and fluids with different residence times are prevented from mixing in the axial direction. This makes the temperature distribution of the reaction material in the radial direction uniform, thereby accurately controlling the reaction process and significantly improving the reaction selectivity. The inventors further discovered that when the outer spiral fins of the heat exchange tubes are multi-threaded, they can maintain or even enhance the aforementioned advantages while significantly reducing reactor pressure drop. This discovery has not been disclosed in the prior art. In fact, based on published literature, those skilled in the art generally believe that because the outer spiral fins of heat transfer tubes have a minimal perturbative effect on the flow of low-speed liquids, do not disrupt the fluid boundary layer, and have no significant impact on mass and heat transfer in liquid-solid reaction systems, they have a particularly minimal impact on the reaction performance of fixed-bed reactors operating at very low liquid hourly space velocities. Therefore, heat transfer tubes with outer spiral fins are not used in fixed-bed reactors operating at very low liquid hourly space velocities.

[0014] Therefore, one object of the present invention is to provide a reactor including a liquid distribution device, which can not only effectively avoid the problem of uneven fluid distribution in the solid particle loading area caused by the channeling phenomenon occurring 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 the 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, reduce heat transfer resistance, thermal stress and reactor pressure drop.

[0015] To achieve the above-mentioned objectives, the present invention provides a reactor comprising a liquid distribution device, in particular a fixed bed reactor, which allows the reaction liquid to be evenly distributed in the radial direction of the reactor and always maintains a piston flow form, thereby reducing axial backmixing of the reaction liquid and reducing the pressure drop in the reactor. At the same time, it can effectively remove a large amount of heat released by the reaction system and reduce the temperature of the reaction hot spot, so that the temperature distribution in the reactor is uniform, thereby improving the intrinsic safety of the reactor.

[0016] A reactor comprising such a liquid distribution device, in particular a fixed bed reactor, is particularly suitable for processes such as reacting ethylene oxide (liquid) with water (liquid) under the action of a solid resin catalyst to produce ethylene glycol, reacting ethylene oxide (liquid) with ethylene glycol (liquid) under the action of a solid resin catalyst to produce diethylene glycol, reacting ethylene oxide (liquid) with diethylene glycol (liquid) under the action of a solid resin catalyst to produce triethylene glycol, reacting propylene oxide (liquid) with water (liquid) under the action of a solid resin catalyst to produce propylene glycol, and reacting butylene oxide (liquid) with water (liquid) under the action of a solid resin catalyst to produce butanediol. While ensuring uniform distribution of the reaction liquid, the heat generated by the reaction can be quickly removed, thereby ensuring uniform temperature distribution in the reaction zone, and can greatly ensure the inherent safety of the chemical process.

[0017] Thus, according to a first aspect of the present invention, the present invention provides a reactor, in particular a fixed bed reactor, comprising a liquid distribution device, wherein the liquid distribution device comprises:

[0018] A heat exchange tube unit comprising 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 spiral fins on their outer walls, wherein the spiral fins on the outer walls of at least a portion of the heat exchange tubes rotate in opposite directions to the spiral fins on the outer walls of adjacently arranged heat exchange tubes (i.e., the spiral fins on the outer walls of at least a portion of the adjacently arranged heat exchange tubes rotate in alternating directions of left and right rotation), and more preferably, the spiral fins on the outer walls of all the heat exchange tubes rotate in opposite directions to the spiral fins on the outer walls of adjacently arranged heat exchange tubes (i.e., the spiral fins on the outer walls of all adjacently arranged heat exchange tubes rotate in alternating directions of left and right rotation); a heat exchange medium flows within the heat exchange tubes, while a liquid reaction material flows outside the heat exchange tubes in a direction substantially parallel to the axial direction of the heat exchange tubes;

[0019] The optional solid particle packing unit comprises solid particles filling the space between the heat exchange tubes. Preferably, the solid particle packing unit is a packed bed or a catalyst bed, more preferably a catalyst bed.

[0020] According to a second aspect of the present invention, the present invention also provides a method for carrying out a heterogeneous catalytic reaction, especially a liquid-solid catalytic reaction, using the above reactor.

[0021] After in-depth research, the inventors surprisingly found that the uniform distribution of local temperature on 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 adjacently arranged heat exchange tubes are alternately left-handed and right-handed, the liquid reaction material is continuously diverted and merged under the combined guidance effect of the left-handed and right-handed outer wall spiral fins of the adjacently arranged heat exchange tubes, limiting the back mixing of reaction materials with different residence times in the axial direction of the reactor, so that the uniformity of the composition distribution of the liquid reaction material in the radial direction is significantly improved, thereby significantly improving 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 a transfer rate of reaction heat through the heat exchange tube.

[0022] More particularly, the liquid reaction materials react on the surface of the catalyst particles loaded between the heat exchange tubes, and under the combined action of the left-handed and right-handed outer wall spiral fins of the adjacently arranged heat exchange tubes and the catalyst particles, the liquid reaction materials are further evenly mixed in the radial direction, so that the temperature is more evenly distributed in the radial direction, and then the composition of the reaction materials is more evenly distributed in the radial direction, thereby significantly improving the reaction kinetics and improving the reaction selectivity.

[0023] More specifically, when the spiral fin of the heat exchange tube is a multi-start thread with a number of thread starts n (n is a positive integer greater than 1), if the pitch of the multi-start thread is the same as the pitch of the single-start thread, while achieving the above technical effects, the helical lead angle of the multi-start thread fin is Approximately the helix angle of a single-start thread Therefore, the multi-threaded fins can better guide the fluid in the axial direction of the heat exchange tube and significantly reduce the pressure drop of the reactor.

[0024] After in-depth research, the inventors found that they are not limited by any theory. For the reactor according to the present invention, when the following conditions are met: the liquid distribution device includes a solid particle filling unit, the specifications and dimensions of each heat exchange tube are the same and evenly 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 Figure 5), the cross-section of the spiral fin on the outer wall of the heat exchange tube is a triangle, half of the length of the base of the triangle is h, half of the vertex angle is θ, the pitch of the spiral fin 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 structural parameters of the spiral fin, the structural parameters of the heat exchange tube arrangement, the reactor heat transfer coefficient, and the reactor pressure drop respectively satisfy the following relationships (1) and (2):

[0025] In the above formula, the characteristic size D e (m) is defined as: Re represents the Reynolds number Pr (Prandtl number) represents the physical property constant. α represents the heat transfer coefficient of the reactor (W / (m 2 K)); ρ represents the density of the reaction liquid (kg / m 3 ), μ represents the viscosity of the reaction liquid (Pa·s); u represents the flow rate of the reaction liquid (m / s), which is calculated as follows: Set the air velocity, such as 1.1h -1 When the volume of catalyst loaded in the reaction tube is determined, the total feed volume flow rate can be determined. The feed volume flow rate of a single repeating unit can be calculated based on the number of repeating units in the catalyst loading area in Figure 5. Then, the feed volume flow rate of a single repeating unit can be divided by the cross-sectional area of ​​a single repeating unit. is the flow rate u (due to the catalyst being loaded into the reaction tube, 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 loaded with catalyst); W and D are shown in Figure 5, respectively, when the heat exchange tubes are arranged in a square, W is the side length of the square (m), and D is the diameter of the heat exchange tube (m); H and h respectively represent the pitch of the triangular spiral fin (m) and half the length of the base of the cross section of the triangular spiral fin (m); θ is half the vertex angle of the triangular spiral fin (in radians); c p represents the constant-pressure specific heat capacity of the liquid (J / (kg·℃)), and λ represents the thermal conductivity of the liquid (W / (m·K)). 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 tubes, and has different values ​​for different rotation directions. When the rotation directions of the spiral fins on the outer walls of all heat exchange tubes are the same, N = 0.37. When the rotation direction of the spiral fins on the outer walls of the heat exchange tubes is opposite to that of the spiral fins on the inner walls of the heat exchange tubes, M = 1.18; when the rotation directions are the same, M = 1. When the rotation directions of the spiral fins on the outer walls of all heat exchange tubes are opposite to those of the spiral fins on the outer walls of the heat exchange tubes, N = 0.88.

[0026] For highly exothermic reactions occurring in the reactor, 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>30W / (m 2 K), preferably α>50W / (m 2 ·K); more preferably α>70W / (m 2 ·K); more preferably α>90W / (m 2 ·K).

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

[0028] In the above Equation (2), ΔP represents the reactor pressure drop (Pa), n is the number of thread heads (dimensionless), d is the number-average diameter of the catalyst particles (m), l represents the height of the fixed bed (m), and the definitions of other parameters are the same as those in Equation (1) above.

[0029] For the reactor of the present invention, especially the fixed bed reactor, a low reactor pressure drop can reduce energy consumption. According to a preferred embodiment, in the above Equation (2), ΔP < 2000 kPa, preferably ΔP < 1000 kPa, more preferably ΔP < 600 kPa, more preferably ΔP < 300 kPa, and still more preferably ΔP < 150 kPa.

[0030] After being verified by multiple tests, the above equation 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 are within plus or minus 10%. Since Pr will decrease with the increase in temperature, for the liquid in the reactor of the present invention (temperature greater than 80 °C), Pr all meets this requirement.

[0031] 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.

[0032] According to the fourth aspect of the present invention, the present invention also provides a method for reducing the pressure drop of a fixed bed reactor, wherein the liquid distribution device of the present invention is used in the fixed bed reactor, and the liquid distribution device includes a heat exchange tube with an outer wall spiral fin in the form of a multi-head thread. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is a schematic structural diagram of a reactor according to an embodiment of the present invention.

[0034] FIG. 2 is an assembled structural diagram of a liquid distribution device according to an embodiment of the present invention (the spiral fins are not shown).

[0035] FIG. 3 is a schematic diagram of a heat exchange tube with an outer wall spiral fin according to the present invention and a partial enlarged view of the spiral fin.

[0036] FIG. 4 is a cross-sectional schematic diagram of a heat exchange tube with an outer wall spiral fin according to the present invention (the cross-sectional shape of the spiral fin is an isosceles triangle).

[0037] FIG5 is a schematic diagram of the arrangement positions of the heat exchange tubes and the catalyst loading area according to the present invention.

[0038] FIG6 is a schematic structural diagram of a liquid reaction material distributor according to the present invention.

[0039] FIG7 is a schematic diagram of the partial structure of the left-handed and right-handed outer wall spiral fins of two adjacently arranged heat exchange tubes according to the present invention.

[0040] FIG8 is a schematic cross-sectional view of a heat exchange tube with spiral fins on the outer and inner walls according to the present invention (the cross-sectional shape of the spiral fins is an isosceles triangle).

[0041] Figure 9 is a schematic diagram showing that the outer wall spiral fins and the inner wall spiral fins of the heat exchange tube rotate in opposite directions, wherein the outer wall spiral fins (indicated by solid lines) are right-handed and the inner wall spiral fins (indicated by dotted lines) are left-handed.

[0042] Figure 10 is a schematic diagram showing that the outer wall spiral fins and the inner wall spiral fins of the heat exchange tube have the same rotation direction, wherein the outer wall spiral fins (indicated by solid lines) are right-handed and the inner wall spiral fins (indicated by dotted lines) are right-handed.

[0043] FIG11 is a diagram showing the flow effect of the reaction fluid when all heat exchange tubes are arranged with right-handed outer wall spiral fins.

[0044] FIG12 is a diagram showing the flow effect of the reaction fluid when heat exchange tubes with left-handed outer wall spiral fins and heat exchange tubes with right-handed outer wall spiral fins are alternately arranged in an axially asymmetric manner.

[0045] FIG13 is a diagram showing the flow effect of the reaction fluid when heat exchange tubes with left-handed outer wall spiral fins and heat exchange tubes with right-handed outer wall spiral fins are alternately arranged in an axially symmetrical manner.

[0046] Figure 14 is a schematic diagram of the structure of the spiral fins on the outer wall of the heat exchange tube, which are single-start threads and multi-start threads respectively. The right figure shows a single-start thread with a pitch of 3H, the left figure shows a single-start thread with a pitch of H, and the middle figure shows a multi-start thread with a pitch of H and the number of thread heads n=3.

[0047] Description of main reference numerals:

[0048] 100: Fixed bed reactor,

[0049] 101: liquid outlet;

[0050] 1: U-shaped heat exchange tube,

[0051] 1A: heat exchange medium inlet,

[0052] 1B: heat exchange medium outlet,

[0053] 10: spiral fins,

[0054] 10A: left-hand spiral fins,

[0055] 10B: right-hand spiral fins,

[0056] 11: Support plate on heat exchange tube,

[0057] 12: Heat exchange tube lower support plate,

[0058] 13: Heat exchange medium inlet main pipe,

[0059] 14: Heat exchange medium outlet main pipe;

[0060] 2: Liquid reaction material distributor,

[0061] 21: liquid outlet;

[0062] 3: Catalyst loading area,

[0063] 31: Catalyst top screen,

[0064] 32: Catalyst bottom screen. Specific implementation plan

[0065] Other features and advantages of the present invention will be described in detail below with reference to the accompanying drawings with reference to the specific embodiments of the present invention.

[0066] It should be understood that the specific embodiments described in this specification are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

[0067] Any specific numerical value disclosed in this specification (including the endpoints of a numerical range) is not limited to the exact value of the numerical value, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within the range of ±5% of the exact value. Moreover, for a disclosed numerical range, the values ​​between the endpoints of the range, between the endpoints and the specific points in the range, and between the specific points can be arbitrarily combined to form one or more new numerical ranges, and these new numerical ranges should also be considered to be specifically disclosed in this specification.

[0068] Unless otherwise specified, the terms used in this specification have the same meanings as those generally understood by those skilled in the art. If a term is defined in this specification and its definition is different from the general understanding in the art, the definition in this specification shall prevail.

[0069] In this specification, except for matters explicitly described, any matters or issues not mentioned are directly applicable to those known in the art without any changes. Moreover, any embodiment described in this specification can be freely combined with one or more other embodiments described in this specification, and the technical solutions or technical ideas formed thereby are considered part of the original disclosure or original description of the present invention, and should not be regarded as new content not disclosed or anticipated in this specification, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0070] All patent and non-patent literature mentioned in this specification, including but not limited to textbooks and journal articles, are incorporated herein by reference in their entirety.

[0071] According to a first aspect of the present invention, the present invention relates to a reactor, in particular a fixed bed reactor, comprising a liquid distribution device, the liquid distribution device comprising:

[0072] A heat exchange tube unit comprising 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 spiral fins on their outer walls, wherein the spiral fins on the outer walls of at least a portion of the heat exchange tubes rotate in opposite directions to the spiral fins on the outer walls of adjacently arranged heat exchange tubes (in other words, the spiral fins on the outer walls of at least a portion of adjacently arranged heat exchange tubes rotate in alternating directions of left and right rotation), and more preferably, the spiral fins on the outer walls of all the heat exchange tubes rotate in opposite directions to the spiral fins on the outer walls of adjacently arranged heat exchange tubes (in other words, the spiral fins on the outer walls of all adjacently arranged heat exchange tubes rotate in alternating directions of left and right rotation); a heat exchange medium flows within the heat exchange tubes, while a liquid reaction material flows outside the heat exchange tubes in a direction substantially parallel to the axial direction of the heat exchange tubes;

[0073] An optional solid particle packing unit includes solid particles filling the spaces between the heat exchange tubes.

[0074] According to one embodiment of the present invention, the reactor is preferably a fixed bed reactor for a liquid-solid reaction system, and the solid bed can be a solid packing bed or a solid catalyst bed, which includes a packing in the form of particles or a solid catalyst filled in the space outside any heat exchange tube.

[0075] According to one embodiment of the present invention, the heat exchange tube unit includes a plurality of vertically arranged heat exchange tubes, and the heat exchange tubes are selected from straight heat exchange tubes or U-shaped heat exchange tubes, preferably U-shaped heat exchange tubes; left-handed or right-handed spiral fins are provided on the outer wall of each heat exchange tube, wherein the outer wall spiral fins of at least a part of the heat exchange tubes have an opposite rotation direction to the outer wall spiral fins of the adjacent heat exchange tubes (in other words, the outer wall spiral fins of at least a part of the adjacent heat exchange tubes have an alternating left-handed and right-handed rotation direction), and more preferably, the outer wall spiral fins of all heat exchange tubes have an opposite rotation direction to the outer wall spiral fins of the adjacent heat exchange tubes (in other words, the outer wall spiral fins of all adjacent heat exchange tubes have an alternating left-handed and right-handed rotation direction).

[0076] It should be understood that when the heat exchange tube is a U-shaped heat exchange tube, the rotation directions of the outer wall spiral fins of the straight tube part of the U-shaped heat exchange tube can be the same or different from each other. In this case, a U-shaped heat exchange tube with outer wall spiral fins is equivalent to two straight heat exchange tubes with outer wall spiral fins with the same or opposite rotation directions.

[0077] In this specification, the term "adjacently arranged heat exchange tubes" refers to two heat exchange tubes arranged in such a way that the distance between their axial centers is smaller than the distance between the axial centers of the two heat exchange tubes and the other heat exchange tubes, and then the two heat exchange tubes are adjacently arranged; if the distance between the axial center of a heat exchange tube and the axial centers of multiple heat exchange tubes is the same and the smallest, then the heat exchange tube is simultaneously arranged adjacent to the multiple heat exchange tubes.

[0078] According to a preferred embodiment, when the pitch of the spiral fin 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 measured in the same length unit.

[0079] According to a preferred embodiment, each of the heat exchange tubes has the same specifications and dimensions and is evenly arranged in the liquid distribution device. Preferably, the inlet ends 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, so 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 the above W and D are measured in the same unit of length.

[0080] 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 according to actual needs and based on their basic knowledge. For example, the diameter D can generally be 7-35 mm; preferably 10-25 mm, and the wall thickness can be about 1 mm.

[0081] According to a preferred embodiment, the liquid reaction material 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.

[0082] After research, the inventors were also surprised to find that in the liquid distribution device of the present invention, the combination of the structural features of solid particles, such as catalyst particles (especially particle sphericity and number average diameter) and the structural features 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 of the present invention, making the fixed bed reactor of the present invention very suitable for carrying out liquid-solid catalytic reactions. According to a specific embodiment, the catalyst bed contains nearly spherical solid catalyst particles with substantially equal particle size, having a sphericity greater than 0.8, preferably greater than 0.85, and more preferably greater than 0.9. Sphericity is measured according to the surface area method well known in the art. Preferably, the number average diameter of the particles of the solid catalyst is d, so that d / W is 0.01-0.2, preferably 0.02-0.1, wherein the above-mentioned W and d are measured in the same length unit.

[0083] According to a preferred embodiment, the heat exchange tubes are U-shaped, with the inlet and outlet ends of each U-shaped tube located on the same side and spaced apart, preferably at the upper end of the reactor. Support plates are provided at both the upper and lower ends of the heat exchange tubes to maintain their upright position.

[0084] 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 rotation directions of 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 can be the same or opposite, preferably opposite.

[0085] According to a preferred embodiment, the spiral fin is a raised structure on the outer wall and / or inner wall of the heat exchange tube, wherein the cross-sectional shape of the raised structure is triangular, semicircular, semi-elliptical or rectangular. When the cross-sectional shape of the raised structure is triangular, it is preferably a nearly isosceles triangle, and more preferably an isosceles triangle; the term "nearly isosceles triangle" means that the length of the two sides of the cross section of the spiral fin raised from the outer wall and / or inner wall differs by less than 10%, preferably less than 5%, and more preferably are equal.

[0086] According to a preferred embodiment, when the cross-sectional shape of the raised structure is a triangle, half of the length 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 degrees and radians of the angle θ can be converted to each other.

[0087] According to a preferred embodiment, the rotation direction of the outer wall spiral fins and the rotation direction of the inner wall spiral fins of the heat exchange tube can be the same or opposite, preferably opposite.

[0088] 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.

[0089] According to a preferred embodiment, the pitch H of the outer spiral fins and the pitch H' of the inner spiral fins of the heat exchange tubes can be the same or different. However, the inventors have discovered that it is particularly advantageous when the pitch H' of the inner spiral fins of the heat exchange tubes is 1-5 times, preferably 2-3 times, the pitch H of the outer spiral fins. This is because it significantly simplifies the manufacturing process of the inner spiral fins and saves manufacturing costs without affecting, and may even further improve, the heat transfer efficiency of the heat exchange tubes, the uniform temperature distribution, and the uniform distribution of the liquid reactants outside the heat exchange tubes.

[0090] According to a preferred embodiment, if the rotation direction of the outer wall spiral fins of the heat exchange tube is the same as the rotation direction of the inner wall spiral fins of the heat exchange tube and the pitch H of the outer wall spiral fins of the heat exchange tube is the same as the pitch H' of the inner wall spiral fins of the heat exchange tube, it is advantageous to make the outer wall spiral fins of the heat exchange tube and the inner wall spiral fins of the heat exchange tube axially displaced by at least 1 / 4 pitch, preferably 1 / 2 pitch; or if the rotation direction of the outer wall spiral fins of the heat exchange tube is opposite to the rotation direction of the inner wall spiral fins of the heat exchange tube and the pitch H of the outer wall spiral fins of the heat exchange tube is the same as the pitch H' of the inner wall spiral fins of the heat exchange tube, it is advantageous to make the outer wall spiral fins of the heat exchange tube and the inner wall spiral fins of the heat exchange tube axially displaced by at most 1 / 4 pitch, preferably there is no dislocation.

[0091] According to a preferred embodiment, when the H / D of the outer wall spiral fins of the heat exchange tube is a certain value, the outer wall spiral fins can be in a single-start thread form or a multi-start thread form. Preferably, the number of thread heads n of the outer wall spiral fins of the heat exchange tube is 1, 2, 3 or 4, preferably 3 or 4.

[0092] According to a preferred embodiment, the liquid distribution device further includes a liquid distributor, which is located above the heat exchange tube unit, and the porosity of the liquid outlet of the liquid distributor is 2‰-75‰, preferably 10‰-60‰, for example 20‰, 30‰, 40‰, 50‰.

[0093] According to a preferred embodiment, the left-handed and right-handed outer wall spiral fins of any pair of adjacently arranged heat exchange tubes are axially offset by at most 1 / 3 of the pitch, preferably at most 1 / 4 of the pitch. More preferably, the left-handed and right-handed outer wall spiral fins of any pair of adjacently arranged heat exchange tubes are not axially offset, that is, they are distributed in mirror symmetry with respect to the axial direction.

[0094] According to a preferred embodiment, screens are provided at both the upper and lower ends of the solid particle loading unit; the screen at the lower end is provided below the bottom of the heat exchange tube to prevent the catalyst particles from leaking out of the gap at the contact point between the screen and the heat exchange tube with outer wall rotating fins, and the screen at the upper end is provided below the liquid distributor.

[0095] According to a preferred embodiment, the heat exchange medium inlet manifold and / or the heat exchange medium outlet manifold of the reactor are located at the top of the reactor, and are arranged at a position higher than the liquid distributor.

[0096] According to a preferred embodiment, the reactor of the present invention is a heterogeneous catalytic reactor, which is used to catalyze hydration reactions to produce ethylene glycol, catalyze reactions to produce diethylene glycol, catalyze reactions to produce triethylene glycol, catalyze reactions to produce propylene glycol, or catalyze reactions to produce butanediol, wherein the liquid reaction materials 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 butylene oxide and liquid water; and the solid catalyst used is selected from resins.

[0097] According to a second aspect of the present invention, the present invention also relates to a method for carrying out a heterogeneous catalytic reaction, characterized in that the reactor described above, in particular a fixed bed reactor, is used.

[0098] According to a preferred embodiment, the method is used to prepare ethylene glycol by catalytic hydration reaction of ethylene oxide, prepare diethylene glycol by catalytic reaction of ethylene oxide and ethylene glycol, prepare triethylene glycol by catalytic reaction of ethylene oxide and diethylene glycol, prepare propylene glycol by catalytic hydration reaction of propylene oxide, or prepare butylene glycol by catalytic hydration reaction of butylene oxide, etc., wherein the liquid reaction materials 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 butylene oxide and liquid water; and the solid catalyst used is selected from resin.

[0099] According to a preferred embodiment, the method is used to prepare ethylene glycol by catalytic hydration reaction of ethylene oxide, wherein the liquid reaction materials are liquid ethylene oxide and liquid water, and the solid catalyst used is a resin.

[0100] According to a preferred embodiment, the method is used to prepare ethylene glycol by catalytic hydration reaction of ethylene oxide, wherein the liquid reaction materials are liquid ethylene oxide and liquid water, and the molar content 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.

[0101] According to a preferred embodiment, liquid ethylene oxide and liquid water flow through a fixed bed reactor, contact a solid catalyst bed loaded on the outside of the heat exchange tubes, and react to produce ethylene glycol, wherein 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, 1.6 MPa, and the liquid hourly space velocity is 0.5-5 h -1 , preferably 1-4h -1 , for example 2h -1 , 3h -1 .

[0102] In the prior art, heat exchange tubes with spiral fins on their outer walls are generally used in heat exchangers, and typically employ an arrangement in which all the spiral fins are either right-handed or left-handed, as shown in Figure 11. However, the inventors have discovered that using heat exchange tubes with spiral fins in fixed-bed reactors, and allowing the reaction fluid to flow parallel to the tube's axis, effectively transfers heat while significantly improving the reaction kinetics, controlling the reaction rate, and significantly increasing the reaction yield and selectivity.

[0103] The inventors further discovered that when all the spiral fins on the outer walls of the heat exchange tubes are arranged in a right-handed pattern, the fluid tends to flow to the left, as shown in Figure 11. Similarly, when all the spiral fins on the outer walls of the heat exchange tubes are arranged in a left-handed pattern, the fluid tends to flow to the right. Because the unidirectional flow of the reaction fluid lacks mutual intersection and mixing, the effect of such flow is that the temperature of the reaction fluid in the catalyst-filled space is unevenly distributed in the radial direction, resulting in a non-uniform distribution of the composition and temperature of the liquid in the radial direction of the fixed bed, which seriously affects the reaction kinetics, yield, and reaction selectivity.

[0104] The inventors also discovered that, as shown in Figure 12, 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 adjacent to each other in a heat exchange tube unit, but the outer wall spiral fins of the two heat exchange tubes are axially misaligned by more than one-third of the pitch, although the reaction fluid produces a flow effect of alternating divergence and convergence in the radial direction of the reactor, streams a and b still have different flow paths and different residence times in the reactor, resulting in a backmixing effect when they converge. The flow effect of the reaction fluid is shown in Figure 12.

[0105] As shown in Figure 13, when heat exchange tubes with left-handed outer wall spiral fins are arranged alternately adjacent to heat exchange tubes with right-handed outer wall spiral fins in a heat exchange tube unit, and the outer wall spiral fins of the two adjacent alternating heat exchange tubes are arranged in mirror-symmetric relationship in the axial direction, the fluid flowing in this structure flows through these mirror-symmetric flow channels and has the same residence time, resulting in a very uniform temperature distribution of the reaction fluid in the radial direction of the reactor, and thus a uniform composition distribution of the reaction fluid in the radial direction of the reactor. The spiral fins have a guiding effect on the fluid, promoting its forward flow, which can reduce or even prevent axial back-mixing of liquids with different residence times. The flow effect of the reaction fluid is shown in Figure 13.

[0106] The inventors further discovered that, as shown in FIG14 , the pitch of the spiral fins on the outer wall of the heat exchange tube unit also has a significant impact on the heat transfer capacity. The smaller the pitch H, the better the heat transfer capacity of the heat exchange tube unit, the smaller the hot spot temperature rise of the reactor, the higher the reaction selectivity, and the better the reaction performance. However, the smaller the single-start thread H, the higher the helix angle of the thread. As the pressure decreases, the resistance encountered by the fluid in the axial direction of the heat exchange tube when passing through the thread will become larger, which will cause the pressure drop of the entire reactor to be too large. When using multi-threaded threads, at the same pitch H as single-threaded threads, while ensuring the same or even better heat transfer effect, it can also significantly reduce the pressure drop of the reactor, optimize the flow state of the fluid on the spiral fins on the outer wall of the heat exchange tube, and improve the reaction performance of the reactor. In Figure 14, the left and right figures show that the outer wall spiral fins are single-threaded with the number of thread heads n=1, and the middle figure shows that the outer wall spiral fins are multi-threaded with the number of thread heads n=3. The pitch of the right figure is larger, and the heat transfer capacity is poor. The pitch of the middle figure is 1 / 3 of the pitch of the right figure, and the heat transfer capacity is enhanced, but the helix angle of the thread in the middle figure is Approximately the spiral angle of the left figure It is three times the diameter of the reactor, which promotes the flow of fluid in the axial direction and significantly reduces the pressure drop of the reactor.

[0107] The liquid distribution device according to the present invention is particularly suitable for fixed bed reactors, and is especially suitable for fixed bed reactors for liquid-solid multiphase catalytic reactions with low liquid hourly space velocity. According to a preferred embodiment, as shown in FIG2 , the liquid distribution device includes a plurality of U-shaped heat exchange tubes of the same specification and size arranged vertically and evenly, so that the inlet and outlet ends of the U-shaped heat exchange tubes are arranged in a square; the heat exchange medium flows in 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 catalyst bed; the liquid reaction material enters the space where the solid catalyst particle bed is located evenly from top to bottom and undergoes a catalytic reaction under the temperature control of the heat exchange medium; during the reaction process, the spiral fins on the outer wall of the U-shaped heat exchange tubes can prevent the liquid reaction material from flowing along the outer wall of the U-shaped heat exchange tubes, thereby maintaining the uniform distribution of the liquid reaction material in the solid catalyst bed. The spiral fins on the outer wall of the heat exchange tube rotate in opposite directions to the spiral fins on the inner wall, which can improve the uniformity of the heat transfer between the outer and inner walls of the heat exchange tube by the spiral fins, reducing heat transfer resistance and thermal stress. Furthermore, the uniform distribution of the local temperature on the outer wall of the heat exchange tube can promote the uniform distribution of the composition of the reaction fluid. In the heat exchange tube unit, the heat exchange tubes with left-handed outer wall spiral fins and the heat exchange tubes with right-handed outer wall spiral fins are arranged alternately adjacent to each other, 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 wall spiral fins of the adjacent alternating heat exchange tubes are distributed in a mirror-symmetrical manner in the axial direction. The converging fluids have the same residence time due to the mirror-symmetrical flow channels, thus avoiding the back-mixing effect of fluids with different residence times when converging.

[0108] Compared with the prior art, the reactor according to the present invention has the following beneficial effects:

[0109] 1) In the prior art, when the liquid reaction material flows through the catalyst bed, due to the gaps between the catalyst particles, it is easy to generate continuous gaps at the position of the smooth outer wall of the heat exchange tube. The liquid will form a "short circuit" at such a position, that is, the flow of the liquid material is easy to concentrate on the outer wall of the heat exchange tube and channeling will occur. The channeling phenomenon on the outer wall of the heat exchange tube will lead to the problem of uneven distribution of the fluid in the catalyst particle loading area. The present invention arranges spiral fins on the outer wall of the heat exchange tube. Through the drainage effect of the spiral fins, the liquid material flowing along the outer wall of the heat exchange tube can be effectively guided to flow in the radial direction, avoiding the occurrence of axial channeling of the liquid material on the outer wall, thereby making the distribution of the fluid in the catalyst particle loading area more uniform; at the same time, it can also effectively reduce the thickness of the liquid film on the outer wall of the heat exchange tube, reduce the heat transfer resistance, and effectively improve the heat transfer capacity;

[0110] 2) Through research, the inventors have also discovered that spiral fins can guide the liquid reactants to flow radially as long as they protrude from the outer wall of the heat exchange tube. This fluid guidance effect is even better when the cross-section of the spiral fin is an isosceles triangle. Further research by the inventors has revealed that the fluid guidance effect is closely related to indicators such as the base and vertex angle of the isosceles triangle. The specific range of values ​​for the ratio h / D of the base h of the isosceles triangle relative to the dimension D of the heat exchange tube diameter and the specific range of angles for the vertex θ employed in the present invention not only effectively avoid channeling on the outer wall of the heat exchange tube, thereby improving the mass and heat transfer capacity of the catalytic reaction, but also prevent excessive resistance to fluid flow through the catalyst bed, thereby reducing reactor pressure drop.

[0111] 3) After research, the inventors also discovered that if spiral fins are arranged on the inner wall of the heat exchange tube so that the position of the inner wall spiral fins does not overlap with the position of the outer wall spiral fins, and the rotation direction of the outer wall spiral fins of the heat exchange tube is opposite to that of the inner wall spiral fins, the area 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 exchange tube is symmetrically distributed about the central axis of the heat exchange tube. This symmetry effectively improves the uniformity of the heat transfer between the outer and inner walls of the heat exchange tube by the spiral fins, avoids excessive local temperature differences between the outer and inner walls of the heat exchange tube, reduces thermal stress, and reduces the adverse effects of deformation caused by thermal stress on the service life of the heat exchange tube. At the same time, the uniform distribution of the local temperature of the outer wall of the heat exchange tube can promote the uniform distribution of the reaction fluid.

[0112] 4) After research, the inventors also found that 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 adjacent to each other. This arrangement makes the heat exchange tubes symmetrical in the vertical direction. This symmetrical structure can guide the flow direction of the reaction fluid. Since the rotation directions of the outer wall spiral fins of adjacent heat exchange tubes are opposite, the liquid material produces a flow effect of alternating diversion and convergence in the radial direction of the reactor, preventing the liquid material from flowing in a single direction, thereby making the distribution of the fluid in the catalyst particle loading area more uniform. The spiral fins also have a guiding effect on the forward flow of the fluid, which can effectively reduce axial liquid backmixing. The combined effect of the above flow effects can effectively improve the reactor conversion rate and selectivity. If the spiral fins on the outer walls of all the heat exchange tubes in the heat exchange tube unit have the same rotation direction, such as all the spiral fins are left-handed or all the spiral fins are right-handed, since the rotation directions of the spiral fins on the outer walls of the heat exchange tubes are consistent, although the liquid material flowing along the outer walls of the heat exchange tubes can be guided to flow in a radial direction, since all the spiral fins have the same rotation direction, the liquid material will tend to flow in one direction, thereby affecting the uniform distribution of the fluid in all directions.

[0113] 5) After research, the inventors also found that the adjacent alternatingly arranged heat exchange tubes with left-handed or right-handed outer wall spiral fins are distributed in a mirror-symmetrical manner in the axial direction, and the converging fluids flow through flow channels with a mirror-symmetrical relationship, thereby having the same residence time. Therefore, there is no back-mixing effect when fluids with different residence times converge. If the adjacent alternatingly arranged heat exchange tubes with left-handed or right-handed outer wall spiral fins are relatively moved a certain distance in the axial direction, and this distance is not an integer multiple of the pitch, this will cause the outer wall spiral fins of the adjacently arranged heat exchange tubes to be staggered in the axial direction and not have a mirror-symmetrical relationship relative to the axial direction. At this time, since the converging fluids have different flow paths, their residence times in the reactor when converging are different, which will cause the fluids with different residence times to have a back-mixing effect, reducing the conversion rate and selectivity of the reaction;

[0114] 6) When using U-shaped heat exchange tubes in the heat exchange tube unit, the inlet and outlet of each U-shaped heat exchange tube are located on the same side and evenly spaced. Since each heat exchange tube adopts the same dimensions, the overall structure of the liquid distribution device is more rational and the radial temperature difference within the reactor is kept to a minimum. Compared with the prior art, in which the outlet and inlet of the U-shaped heat exchange tubes are symmetrically arranged on both sides of the reactor's radial direction, resulting in a significant temperature difference between the two sides of the reactor, the present invention can effectively improve the reaction uniformity in the radial direction of the reactor, avoid the additional thermal stress caused by the large radial temperature difference and cause thermal deformation of the reactor, thereby increasing the reactor's service life.

[0115] 7) The present invention arranges the inlet and outlet ends of two adjacent U-shaped heat exchange tubes in a square shape, 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. Experiments have shown that this square arrangement can further improve the flow uniformity of the liquid reactant in the catalyst bed compared to rectangular or diamond-shaped arrangements.

[0116] 8) When the number of thread heads of the spiral fins on the outer wall of the heat exchange tube according to the present invention is multiple, compared with single-start threads, at the same pitch H, the multiple-start threads have a larger helical lead angle, and the spiral fins have more axial guide effects on the fluid outside the heat exchange tube, which can significantly reduce the pressure drop of the reactor.

[0117] 9) The present invention sets the screen at the lower end of the catalyst bed below the bottom of the heat exchange tube, which can effectively reduce the risk of catalyst leakage caused by the heat exchange tube passing through the screen and reduce the difficulty of reactor manufacturing and processing;

[0118] 10) The present invention proposes a dimensionless quasi-numerical correlation formula for calculating the heat transfer and pressure drop of a reactor with spiral fins, and the calculation error meets the requirements for engineering use.

[0119] 11) The present invention is particularly suitable for use in fixed-bed reactors for heterogeneous catalytic reactions, that is, in application scenarios where the reaction materials are all in liquid phase and the catalyst is solid catalyst particles; it is particularly suitable for use in processes such as preparing ethylene glycol by catalytic hydration reaction of ethylene oxide, preparing diethylene glycol by catalytic reaction of ethylene oxide and ethylene glycol, preparing triethylene glycol by catalytic reaction of ethylene oxide and diethylene glycol, preparing propylene glycol by catalytic hydration reaction of propylene oxide, and preparing butanediol by catalytic hydration reaction of butylene oxide.

[0120] The above description is merely a summary of the technical solution of the present invention. In order to more clearly 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 purposes, technical features and advantages of the present invention easier to understand, a number of preferred embodiments and comparative examples are listed below and explained in detail with the accompanying drawings.

[0121] Unless expressly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising” will be understood to include the stated elements or components but not to exclude other elements or components.

[0122] In this specification, for convenience of description, spatially relative terms such as "below", "beneath", "down", "above", "above", etc. may be used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that the spatially relative terms are intended to include different orientations of the object in use or operation in addition to the orientation depicted in the drawings. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above directions. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatially relative terms used in this specification should be interpreted accordingly.

[0123] As shown in Figures 1 to 14, the present invention provides an embodiment of a liquid distribution device in which the heat exchange tubes are U-shaped heat exchange tubes. The device is primarily used in heterogeneous catalytic reaction systems, and is particularly suitable for catalytic reactions of liquid materials under the action of a solid catalyst bed at relatively mild reaction temperatures (e.g., approximately 100°C). Examples include the heterogeneous catalytic hydration of ethylene oxide to produce ethylene glycol, the catalytic reaction of ethylene oxide and ethylene glycol to produce diethylene glycol, the catalytic reaction of ethylene oxide and diethylene glycol to produce triethylene glycol, the heterogeneous catalytic hydration of propylene oxide to produce propylene glycol, and the heterogeneous catalytic hydration of butylene oxide to produce butanediol. Because these reactions are highly exothermic, a heat exchange tube unit is required to maintain a relatively stable reaction temperature during the reaction. The reaction temperature is controlled by passing a heat exchange medium (cooling or heating) through the heat exchange tubes of the heat exchange tube unit.

[0124] As shown in Figure 1, the upper and lower ends of the U-shaped heat exchange tube 1 of the present invention are provided with support plates, namely the upper support plate 11 of the heat exchange tube 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 tubes 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, namely the catalyst top screen 31 and the catalyst bottom screen 32 in Figure 1. This can confine the filled catalyst particles to the effective area between the heat exchange tubes 1. Preferably, but not restrictively, the catalyst bottom screen 32 is provided below the bottom of the heat exchange tube 1. Since the catalytic reaction liquid material of the present invention enters the reactor from the top, there is no leakage problem of the reactor top screen. In order to prevent the catalyst from leaking from the bottom screen of the reactor, the bottom of the U-shaped heat exchange tube 1 is provided above the bottom screen 32, that is, it does not pass through the catalyst screen. This can effectively reduce the risk of catalyst leakage caused by the U-shaped heat exchange tube passing through the screen and reduce the difficulty of reactor manufacturing and processing.

[0125] According to a 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, and they are arranged vertically. The inlet end (i.e., the heat exchange medium inlet 1A in Figure 2) and the outlet end (i.e., the heat exchange medium outlet 1B in Figure 2) of each U-shaped heat exchange tube 1 are located on the same side and are spaced apart. "The inlet end and the outlet end are located on the same side" means that heat exchange tubes of the same specifications are arranged regularly, so that an inlet-outlet-inlet-outlet arrangement can be formed, making the overall structure of the liquid distribution device more reasonable and the radial temperature difference in the reactor can be controlled to a smaller value. Compared with the prior art in which the outlet and inlet of the U-shaped heat exchange tubes are arranged on both sides of the radial direction of the reactor, resulting in a significant temperature difference on both sides of the reactor, the present invention can effectively improve the uniformity of the reaction on the radial cross-section of the reactor, avoid the additional thermal stress caused by the radial temperature difference causing thermal deformation of the reactor, and increase the service life of the reactor. The outer wall of the heat exchange tube is provided with a spiral fin 10 (refer to FIG3 ). Furthermore, preferably but not restrictively, the spiral fin may be a raised structure on the outer wall of the heat exchange tube, and the cross-section of the raised structure may be in a triangular, semicircular, semi-elliptical or rectangular shape. The purpose of providing the spiral fin is not only to solve the problem of uneven distribution of fluid in the catalyst particle loading area caused by the channel flow phenomenon of the liquid on the outer wall of the U-shaped tube in the prior art, but also to make the fluid flow along the radial direction of the reactor, thereby promoting the uniform distribution of the composition and temperature of the fluid in the radial direction. 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 (refer to the catalyst loading area 3 in FIG5 ), which is filled with solid catalyst particles; the liquid reaction material flows in the space to carry out the catalytic reaction.

[0126] In the prior art, when liquid reaction materials flow in a catalyst bed, due to the presence of gaps between the catalyst particles, continuous gaps are easily generated at locations on the smooth outer wall of the heat exchange tube. The liquid in such locations will form a "short circuit," that is, the liquid material will easily concentrate on the outer wall of the heat exchange tube and cause channeling. Since channeling on the outer wall of the U-shaped heat exchange tube can lead to uneven distribution of the fluid in the catalyst, the present invention provides spiral fins on the outer wall of the U-shaped heat exchange tube. Through the action of the spiral fins, the liquid material flowing along the outer wall of the heat exchange tube can be effectively guided to flow in a radial direction, avoiding channeling, thereby making the distribution of the fluid in the catalyst particle loading area more uniform. At the same time, since channeling is avoided, the thickness of the liquid film on the outer wall of the heat exchange tube can be effectively reduced, reducing the heat transfer resistance, thereby more effectively improving the heat transfer capacity.

[0127] As shown in Figures 3 and 4, preferably, but not restrictively, the cross section of the raised structure of spiral fin 10 can be an isosceles triangle. After study, the inventors have also found that spiral fin 10 can guide liquid reaction material to flow radially as long as it protrudes from the outer wall of heat exchange tube 1, but when the cross section of spiral fin is an isosceles triangle, the effect of guiding liquid is better. After study, the inventors have further found that the effect of guiding liquid is also closely related to the indexes such as the base and the vertex angle of the isosceles triangle. When the pitch of spiral fin 10 is H, the diameter (excluding spiral fin height) of heat exchange tube 1 is D, according to the present invention, ratio H / D is within the range of 0.2-1.7, preferably 0.3-1.3, such as 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 and 1.2. When half the length of 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, such as 0.05, 0.06, 0.07, and 0.08, and θ is in the range of 10° to 60°, preferably 20° to 50°, such as 20°, 25°, 30°, 35°, 40°, 45°, or 50°. Through further research, the inventors discovered that the range of the ratio h / D of the base h of the isosceles triangle relative to the diameter D of the heat exchange tube and the range of the vertex angle θ used in the present 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 does not generate significant resistance to the axial flow of the fluid. If h is fixed, if θ is too large, the fin structure will be smoother, reducing the spiral fin's ability to disturb the liquid and limiting its ability to guide radial flow. This will reduce the spiral fin's ability to reduce channeling on the outer wall of the heat exchange tube and enhance heat transfer. If θ is too small, the spiral fin structure will be too sharp, effectively adding a raised obstacle in front of the fluid, creating significant resistance to axial flow and creating thicker stagnant layers above and below the spiral fins. This will also reduce the spiral fin's ability to enhance mass transfer. Using spiral fins with these dimensions can further optimize the aforementioned technical effects.

[0128] As further shown in Figure 5, preferably but not restrictively, two adjacent U-shaped heat exchange tubes are arranged closely (refer to the left side of Figure 5), the inlet and outlet ends of the two heat exchange tubes can be arranged in a square, and the rotation directions of the spiral fins on the outer walls of two adjacent heat exchange tubes are opposite; 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, preferably 1.8-2.4, for example 1.8, 1.9, 2.0, 2.1, 2.2 and 2.3. After research, the inventors also found that the larger the distance between the axial centers of the two U-shaped heat exchange tubes 1 (that is, the side length W of the square), the larger the space for loading the catalyst and the greater the production capacity of the reactor, but the heat transfer area corresponding to the unit volume of catalyst will decrease. The smaller W is, the smaller the space for loading the catalyst and the production capacity of the reactor will decrease, but the heat transfer area corresponding to the unit volume of catalyst will increase, which helps to remove the heat generated in the reaction, avoid excessive temperature rise, reduce the occurrence of side reactions, and also improve the intrinsic safety characteristics of the reactor. The present invention adopts a square arrangement, and makes the ratio of the side length W of the square to the diameter D of the heat exchange tube within the above range. Experiments have shown that, compared with the rectangular or diamond arrangement, the square arrangement can further improve the flow uniformity of the liquid reaction material in the catalyst loading area, and can effectively reduce the hot spot temperature rise of the reactor. Moreover, due to the use of a specific liquid distribution device in the reactor of the present invention, the production capacity of the reactor of the present invention is significantly improved.

[0129] As further shown in Figures 8 to 10, spiral fins are also provided on the inner wall of the heat exchange tube. Preferably, but not restrictively, the outer wall spiral fins of the heat exchange tube rotate in opposite directions to the inner wall spiral fins. Through further research, it was found that when the outer wall spiral fins of the heat exchange tube rotate in opposite directions to the inner wall spiral fins, and when the pitch of the outer wall spiral fins of the heat exchange tube is not misaligned with the pitch of the inner wall spiral fins, as shown in Figure 9, the area covered by the spiral fins can be made more symmetrical. The area formed by the spiral fins and the outer wall of the heat exchange tube in this arrangement shows a certain degree of symmetry about the central axis of the heat exchange tube. This symmetry can effectively improve the uniformity of the enhanced heat transfer of the spiral fins to the outer and inner walls of the heat exchange tube, avoid excessive local temperature differences between the outer and inner walls of the heat exchange tube, reduce thermal stress, and reduce the adverse effects of deformation caused by thermal stress on the service life of the heat exchange tube. At the same time, the uniform distribution of the local temperature of the outer wall of the heat exchange tube can promote the uniform distribution of the reaction fluid. When the spiral fins on the outer wall of the heat exchange tube and the spiral fins on the inner wall rotate in the same direction and there is a 1 / 2 pitch offset, as shown in Figure 10, 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 does not have the advantages of the structure shown in Figure 9.

[0130] As further shown in Figures 11 and 13, preferably but not restrictively, in the heat exchange tube unit, the heat exchange tubes with left-handed outer wall spiral fins and the heat exchange tubes with right-handed outer wall spiral fins are arranged alternately adjacent to each other, and the adjacent alternately arranged heat exchange tubes are distributed in a mirror-symmetrical manner in the axial direction. Through further research, the inventors found that this arrangement makes the heat exchange tubes present a certain symmetry in the axial direction of the reactor. This symmetrical structure can play a good role in the uniform distribution of the reaction fluid in the radial direction, and when the rotation directions of the outer wall spiral fins of the adjacently arranged heat exchange tubes are opposite, this can cause the liquid material flowing through the spiral fins to produce a flow effect of alternating diversion and convergence in the radial direction of the reactor. This avoids the liquid material from deviating in a single direction due to the outer wall spiral fins of all heat exchange tubes having the same rotation direction. When liquid materials flow in a reactor having 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 adjacent to each other, the residence time of the fluids at convergence is the same, and low raw material conversion rate and low selectivity caused by the back-mixing effect of fluids with different residence times will not occur.

[0131] As further shown in FIG14 , preferably, but not limiting of this, the number of thread starts n of the spiral fins on the outer wall of the heat exchange tube is greater than 1, and preferably, the number of thread starts n is 2, 3, or 4. The inventors have discovered through research that, compared with single-start threads, spiral fins with multiple threads have a larger helix angle at the same pitch H, providing better axial flow guidance for the reaction fluid outside the heat exchange tube, and significantly reducing the pressure drop in the reactor.

[0132] The liquid distribution device of the present invention is particularly suitable for heterogeneous catalytic reactions. The heterogeneous catalytic reactor can be selected from a reactor for producing ethylene glycol by catalytic hydration, a reactor for producing diethylene glycol by catalytic reaction of ethylene oxide and ethylene glycol, a reactor for producing triethylene glycol by catalytic reaction of ethylene oxide and diethylene glycol, a reactor for producing propylene glycol by catalytic hydration, or a reactor for producing butanediol by catalytic hydration; the liquid reaction materials 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 butylene oxide and liquid water; and the solid catalyst used can be selected from resins.

[0133] According to a preferred embodiment, as shown in Figures 1 and 2, the present invention also provides a fixed bed reactor (fixed bed is not shown), which includes the aforementioned liquid distribution device. The heat exchange medium inlet manifold 13 and the heat exchange medium outlet manifold 14 of the fixed bed reactor are both located at the top of the reactor, and are arranged at a position higher than the liquid distributor. The heat exchange medium inlet 1A of all U-shaped heat exchange tubes is connected to the heat exchange medium inlet manifold 13, and the heat exchange medium outlet 1B of all U-shaped heat exchange tubes is connected to the heat exchange medium outlet manifold 14. Furthermore, the liquid distributor 2 is located above the reactor, and the flow direction of the reaction fluid is parallel to the axis of the reactor. With further reference to Figure 6, the liquid outlet 21 of the liquid distributor 2 is preferably arranged in the middle area above the solid particle loading unit, so that the descending liquid material can be ensured to be as evenly distributed as possible in the catalyst loading area. The porosity of the distributor liquid outlet can be 2‰-75‰.

[0134] The present invention also provides a reaction method using the aforementioned fixed bed reactor, wherein the fixed bed reactor is suitable for conducting multiphase catalytic reactions, and comprises a plurality of U-shaped heat exchange tubes of the same specifications and sizes arranged vertically and uniformly, wherein the inlet and outlet ends of the U-shaped heat exchange tubes are spaced apart; 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 reaction material uniformly enters the solid catalyst bed from top to bottom and undergoes a catalytic reaction on the catalyst surface under the temperature control of the heat exchange medium; during the reaction process, the spiral fins on the outer wall of the U-shaped heat exchange tubes prevent the occurrence of channeling on the outer wall, so as to maintain a uniform distribution of the liquid phase in the solid catalyst bed. The outer spiral fins of the heat exchange tube rotate in opposite directions to the inner spiral fins. The area formed by the outer spiral fins of the heat exchange tube and the outer wall of the heat exchange tube is symmetrical about the central axis of the heat exchange tube. This symmetry can effectively improve the uniformity of the heat transfer between the outer and inner walls of the heat exchange tube by the spiral fins, avoid excessive local temperature differences between the outer and inner walls of the heat exchange tube, and reduce thermal stress. By arranging the heat exchange tubes with left-handed outer spiral fins and the heat exchange tubes with right-handed outer spiral fins adjacent to each other in the heat exchange tube unit, and the adjacent alternating heat exchange tubes with left-handed outer spiral fins and the heat exchange tubes with right-handed outer spiral fins are distributed in a mirror-image symmetric manner in the axial direction, the liquid material flowing through the spiral fins is separated and converged, thereby ensuring the uniform radial distribution of the liquid in the solid catalyst bed. At the same time, the spiral fins' guiding effect on the fluid flow can enhance the radial flow of the liquid while reducing axial back-mixing. The above effects can improve the raw material conversion rate and reaction selectivity. Preferably, but not limiting, the reaction method can be used to prepare ethylene glycol by catalytic hydration reaction of ethylene oxide, prepare diethylene glycol by catalytic reaction of ethylene oxide and ethylene glycol, prepare triethylene glycol by catalytic reaction of ethylene oxide and diethylene glycol, prepare propylene glycol by catalytic hydration reaction of propylene oxide, prepare butanediol by catalytic hydration reaction of butylene oxide, etc. In the process of preparing ethylene glycol, liquid ethylene oxide and liquid water are used as liquid reaction materials, and the solid catalyst used is selected from resin; wherein the reaction temperature is 85-150°C, the pressure is 1.0-1.8 MPa, and the reaction time is 0.5-5 hours. -1 Under the space velocity condition of , the liquid reaction material contacts and reacts with the solid catalyst loaded on the outside of the heat exchange tube in the fixed bed reactor of the present invention to produce ethylene glycol with high selectivity and high yield.

[0135] Example

[0136] The following examples illustrate preferred embodiments of the present invention and are in no way intended to limit the scope of the present invention. In these examples, feedstock conversion was calculated by measuring the change in ethylene oxide concentration at the reactor inlet and outlet; ethylene oxide concentration was measured by gas chromatography; ethylene glycol selectivity was calculated by measuring the ethylene glycol concentration at the reactor outlet; and the reactor hotspot temperature rise was measured by inserting a cannula into the center catalyst bed shown in Figure 5 , inserting a thermocouple into the cannula, and moving it up and down. The maximum hotspot temperature rise typically occurs at the top of the catalyst bed, i.e., at a distance of approximately 20% of the catalyst bed height from the top of the catalyst bed. However, the hotspot location can vary with process conditions such as liquid hourly space velocity and feedstock ratio. Reactor pressure drop is the difference between the reaction fluid inlet and outlet pressures, measured using a differential pressure gauge. Other parameters were measured according to conventional methods in the art.

[0137] Example 1

[0138] This example uses a fixed-bed reactor for producing ethylene glycol by heterogeneous catalytic hydration, as shown in Figure 1. The reactor has a diameter of 500 mm and a fixed bed height of 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 U-shaped tubes are provided with spiral fins with an isosceles triangular cross-section on their outer walls, and with spiral fins with an isosceles triangular cross-section on their inner walls. Some of the outer spiral fins on the heat exchange tubes are left-handed, while others are right-handed. Both the inner and outer spiral fins on the heat exchange tubes have single-start threads with n = 1 thread start. The inner and outer spiral fins on the same heat exchange tube rotate in opposite directions and have the same pitch. Within the heat exchange tube unit, heat exchange tubes with left-handed outer spiral fins are arranged alternately adjacent to heat exchange tubes with right-handed outer spiral fins. As shown in Figure 13, two adjacent U-shaped heat exchange tubes are arranged in mirror-image symmetry. The cross section of the outer spiral fin is the same as that of the inner spiral fin of the heat exchange tube, where the ratio of h to the diameter D of the U-shaped heat exchange tube is 0.08, and θ is 30°. The ratio of the pitch H to D is 0.5, and the corresponding helical angle is The angle of the U-shaped heat exchange tubes is 14°. The ratio of the distance W between the axis of the two adjacent heat exchange tubes and the diameter D of the U-shaped heat exchange tubes is 2. The opening rate of the liquid distributor is 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 about 0.1. The liquid reaction material passes through the liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this fixed-bed reactor showed a feedstock conversion greater than 99.9%, an ethylene glycol selectivity greater than 99.9%, a hot spot temperature rise of 3.5°C, and a pressure drop of 165 kPa.

[0139] Example 2

[0140] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as that of Example 1, except that θ is 45°. The liquid material is passed through a liquid distributor with an opening rate of 40‰ at a rate of 1.1 h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion exceeding 99.9%, an ethylene glycol selectivity of 99.7%, a hot spot temperature rise of 3.7°C, and a pressure drop of 135 kPa.

[0141] Example 3

[0142] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as that of Example 1, but the difference is that the ratio of h to the diameter D of the U-shaped heat exchange tube is 0.04. The liquid material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion exceeding 99.9%, an ethylene glycol selectivity of 99.5%, a hot spot temperature rise of 3.8°C, and a pressure drop of 126 kPa.

[0143] Example 4

[0144] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, but the difference is that the ratio W / D of the distance between the centers of two adjacent heat exchange tubes and the diameter D of the U-shaped heat exchange tube is 2.5. The liquid material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion greater than 99.9%, an ethylene glycol selectivity of 99.0%, a hot spot temperature rise of 4.2°C, and a pressure drop of 105 kPa.

[0145] Example 5

[0146] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as that of Example 1, but the difference is that the ratio of the pitch H to D is 1. The liquid material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion exceeding 99.9%, an ethylene glycol selectivity of 99.2%, a hot spot temperature rise of 4.0°C, and a pressure drop of 80 kPa.

[0147] Example 6

[0148] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, except that the ratio of the pitch H to 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 1.7. The liquid material is passed through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion greater than 99.9%, an ethylene glycol selectivity of 99.8%, a hot spot temperature rise of 3.6°C, and a pressure drop of 129 kPa.

[0149] Example 7

[0150] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, except that the ratio of the pitch H to 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 is 1.7, and θ is 20°. The liquid material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity of 1000 sq ft was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion greater than 99.9%, an ethylene glycol selectivity of 99.2%, a hot spot temperature rise of 4.1°C, and a pressure drop of 101 kPa.

[0151] Example 8

[0152] This embodiment uses a fixed bed reactor similar to that of embodiment 1 and similar operating parameters as that of embodiment 1, except that the ratio of the pitch H to 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 is 2.2, the ratio h to the diameter D of the U-shaped heat exchange tube is 0.1, and θ is 20°. The liquid material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion greater than 99.9%, an ethylene glycol selectivity of 98.9%, a hot spot temperature rise of 4.5°C, and a pressure drop of 83 kPa.

[0153] Example 9

[0154] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as that of Example 1, but the difference is that the spiral fins on the inner wall and the outer wall of the same heat exchange tube have the same rotation direction and the same pitch. The liquid material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion exceeding 99.9%, an ethylene glycol selectivity of 99.0%, a hot spot temperature rise of 4.2°C, and a pressure drop of 167 kPa.

[0155] Comparing Example 9 with Example 1, it can be seen that because the rotation direction of the inner spiral fins of the heat exchange tubes included in the reactor used in Example 1 is opposite to that of the outer spiral fins, the feedstock conversion rate and ethylene glycol selectivity of the reactor according to Example 1 are both higher than those of Example 9, and the hot spot temperature of the reactor of Example 1 is lower. This demonstrates that the rotation direction of the inner and outer spiral fins of the heat exchange tubes in the reactor has a synergistic effect on the performance of the reactor.

[0156] Comparative Example 1

[0157] This comparative example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, except that the spiral fins on the outer wall of the straight tube portion of all U-shaped heat exchange tubes rotate in a right-hand direction, and any two adjacent U-shaped heat exchange tubes are arranged as shown in Figure 11; the spiral fins on the inner wall of the heat exchange tube rotate in the opposite direction to the spiral fins on the outer wall of the heat exchange tube. The liquid reaction material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h.-1 A liquid hourly space velocity of 1000 sq ft was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion of 98.2%, an ethylene glycol selectivity of 98.3%, a hot spot temperature rise of 4.9°C, and a pressure drop of 162 kPa.

[0158] In Comparative Example 1, the spiral fins on the outer wall are not arranged alternately in left-right rotation, which makes the flow pattern worse. Although the hot spot temperature increases, the conversion rate decreases significantly.

[0159] Comparative Example 2

[0160] This comparative example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, except that the spiral fins on the outer wall of the straight tube portion of the U-shaped heat exchange tube all rotate in a counterclockwise direction, and two adjacent U-shaped heat exchange tubes are arranged as shown in Figure 11. The spiral fins on the inner wall of the heat exchange tube rotate in the opposite direction to the spiral fins on the outer wall. The liquid reaction material is passed through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity of 1000 sq ft was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion of 98.2%, an ethylene glycol selectivity of 98.2%, a hot spot temperature rise of 4.9°C, and a pressure drop of 163 kPa.

[0161] Comparative Example 3

[0162] This comparative example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, except that the rotation direction of the spiral fins on the outer wall of the straight tube portion of the U-shaped heat exchange tube is all counterclockwise, and two adjacent U-shaped heat exchange tubes are arranged as shown in Figure 11. The rotation direction of the spiral fins on the inner wall of the heat exchange tube is the same as that of the spiral fins on the outer wall, and the pitch of the spiral fins on the inner wall and the outer wall is equal. The liquid reaction material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion of 98.9%, an ethylene glycol selectivity of 97.6%, a hot spot temperature rise of 5.7°C, and a pressure drop of 163 kPa.

[0163] Comparative Example 4

[0164] This comparative example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, except that the spiral fins on the outer wall of the straight tube portion of the U-shaped heat exchange tube all rotate in a right-hand direction, and two adjacent U-shaped heat exchange tubes are arranged as shown in Figure 11. The spiral fins on the inner wall of the heat exchange tube rotate in the same direction as the spiral fins on the outer wall, and the pitch of the spiral fins on the inner and outer walls is equal. The liquid reaction material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion of 99.0%, an ethylene glycol selectivity of 97.6%, a hot spot temperature rise of 5.7°C, and a pressure drop of 162 kPa.

[0165] Comparative Example 5

[0166] This comparative example used a fixed-bed reactor similar to that used in Example 1 and similar operating parameters, except that the spiral fins on the outer wall of the straight tube portion of the U-shaped heat exchange tube all rotated in a counterclockwise direction, and two adjacent U-shaped heat exchange tubes were arranged as shown in Figure 11. There were no spiral fins on the inner wall of the heat exchange tube. The liquid reaction material passed through a liquid distributor with an opening ratio of 40‰ at a rate of 1.1 h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion greater than 99.9%, an ethylene glycol selectivity of 94.9%, a hot spot temperature rise of 9.7°C, and a pressure drop of 162 kPa.

[0167] 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 loading area more uniform, significantly improve the raw material conversion rate and selectivity, and significantly reduce the hot spot temperature of the reactor.

[0168] Comparative Example 6

[0169] This comparative example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as Example 1, but the difference is that there are no spiral fins on the outer and inner walls of the U-shaped heat exchange tubes. The liquid reaction material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion greater than 99.9%, an ethylene glycol selectivity of 90.2%, a hot spot temperature rise of 19.8°C, and a pressure drop of 11 kPa.

[0170] In Comparative Examples 1 to 6, as the hot spot temperature rises, the reaction conversion rate increases, but the selectivity decreases. The results of the above examples and comparative examples are listed in Table 1 below.

[0171] Table 1

[0172] Example 10

[0173] This comparative example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, except that the spiral fins on the outer wall of the straight tube portion of two adjacent U-shaped heat exchange tubes are axially offset by 1 / 4 of the pitch. The liquid reaction material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity of 1000 sq ft was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion of 99.5%, an ethylene glycol selectivity of 99.6%, a hot spot temperature rise of 3.5°C, and a pressure drop of 164 kPa.

[0174] Example 11

[0175] This comparative example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters as those of Example 1, except that the spiral fins on the outer wall of the straight tube portion of two adjacent U-shaped heat exchange tubes are axially offset by 1 / 2 pitch. The liquid reaction material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity of 1000 sq ft was fed into the reactor, with a molar ratio of liquid water to liquid ethylene oxide of 5:1. Ethylene glycol was synthesized in the reactor via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor showed a feedstock conversion of 99.1%, an ethylene glycol selectivity of 99.3%, a hot spot temperature rise of 3.5°C, and a pressure drop of 165 kPa.

[0176] The axial staggered arrangement of the spiral fins on the outer walls of the straight sections of two adjacent U-shaped heat exchange tubes did not affect heat transfer performance. The hotspot temperature rises were the same in Examples 1, 10, and 11. However, axial staggering resulted in backmixing, reducing the reaction conversion and selectivity. The greater the axial staggering, the greater the reduction in conversion and selectivity. The results of these examples are listed in Table 2 below.

[0177] Table 2

[0178] Example 12

[0179] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters. The pitch of the outer wall spiral fins of the heat exchange tubes of this example is equal to that of the outer wall spiral fins in Example 1, but the difference is that the number of thread starts of the outer wall spiral fins is n=3. When the ratio of pitch H to D is H / D of 0.5, the corresponding helical angle is The liquid material passes through the liquid distributor with an opening rate of 40‰ at a speed of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion greater than 99.9%, an ethylene glycol selectivity greater than 99.9%, a hot spot temperature rise of 3.5°C, and a pressure drop of 101 kPa.

[0180] By comparing Example 1 and Example 12, it can be seen that the spiral pitch angle of the spiral fin in Example 12 is 2.6 times larger than that of Example 1. The spiral fin in Example 12 with the number of thread heads n=3 can reduce the reactor pressure drop by about 39%.

[0181] Example 13

[0182] This example uses a fixed bed reactor similar to that of Example 1 and similar operating parameters, and the number of threads n of the spiral fins on the outer wall of the heat exchange tube is 1, but the difference is that the ratio H of the pitch H of the spiral fins on the outer wall to the diameter D of the heat exchange tube is 1.5. The liquid reaction material passes through a liquid distributor with an opening rate of 40‰ at a rate of 1.1h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion exceeding 99.9%, an ethylene glycol selectivity of 98.7%, a hot spot temperature rise of 4.8°C, and a pressure drop of 53 kPa.

[0183] The spiral angle of the outer wall spiral fins of Example 12 and Example 13 Similarly, although the pressure drop of the reactor in Example 12 is greater than that of the reactor in Example 13, the hot spot temperature rise of the reactor in Example 12 is lower and the selectivity of ethylene glycol is higher.

[0184] Table 3

[0185] Example 14

[0186] This embodiment uses a fixed bed reactor similar to that of embodiment 1 and has similar operating parameters as embodiment 1, but the difference is that the cross section of the spiral fins on the outer wall of the heat exchange tube is semicircular, the ratio of the semicircular radius to the diameter D of the U-shaped heat exchange tube is 0.08, the ratio of the pitch H to D (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 (W / D) is 1.7. The liquid material passes through a liquid distributor with an opening rate of 40‰ at a rate of 0.9h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion greater than 99.9%, an ethylene glycol selectivity of 99.0%, a hot spot temperature rise of 4.3°C, and a pressure drop of 92 kPa.

[0187] Example 15

[0188] This embodiment uses a fixed bed reactor similar to that of Example 1 and has similar operating parameters as Example 1, but the difference is that the cross section of the spiral fins on the outer wall of the heat exchange tube is rectangular, the side of the rectangle close to the wall is the longer side, and 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 (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 (W / D) is 1.7. The liquid material passes through a liquid distributor with an opening rate of 40‰ at a rate of 0.9h. -1 A liquid hourly space velocity (LHSV) of 500 nm was fed into a reactor with a molar ratio of liquid water to liquid ethylene oxide of 5:1, where ethylene glycol was synthesized via a catalytic hydration reaction. Measurements of the ethylene glycol synthesis reaction in this reactor demonstrated a feedstock conversion exceeding 99.9%, an ethylene glycol selectivity of 99.1%, a hot spot temperature rise of 4.2°C, and a pressure drop of 137 kPa.

[0189] The above Examples 14 and 15 also confirm that when the cross-section of the spiral fins on the outer wall of the heat exchange tube is rectangular and semicircular, as long as the spiral fins on the outer wall of the adjacently arranged heat exchange tubes are alternately left-handed and right-handed, the obtained reactor can also enable the reaction occurring therein to have high conversion rate, high selectivity and low pressure drop.

[0190] The foregoing description of the 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 clear that, based on the above teachings, those skilled in the art can make many changes and variations. The purpose of selecting and describing the embodiments is to illustrate the practical application of the technical solutions of the present invention and the advantages over the prior art, so that those skilled in the art can implement and utilize various different embodiments of the present invention and make various different choices and changes. Any simple modifications, equivalent changes and modifications made to the above embodiments should fall within the scope of protection of the present invention.

Claims

1. A reactor comprising a liquid distribution device, preferably a fixed bed reactor, characterized in that The liquid distribution device comprises: A heat exchange tube unit, comprising a plurality of vertically arranged heat exchange tubes, at least a portion, preferably all of the heat exchange tubes having left-handed or right-handed spiral fins on their outer walls, wherein the spiral fins on the outer walls of at least a portion of the heat exchange tubes rotate in opposite directions to the spiral fins on the outer walls of the adjacently arranged heat exchange tubes, preferably all of the spiral fins on the outer walls of the heat exchange tubes rotate in opposite directions to the spiral fins on the outer walls of the adjacently arranged heat exchange tubes; 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 filling unit comprises solid particles filling the space between the heat exchange tubes.

2. The reactor according to claim 1, characterized in that The heat exchange tube is selected from a straight tube heat exchange tube or a U-shaped heat exchange tube, wherein the rotation direction of the spiral fins on the outer wall of the straight tube part of the U-shaped heat exchange tube 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, and preferably, support plates are provided at both the upper and lower ends of the heat exchange tube.

3. The reactor according to any one of claims 1 to 2, characterized in that Spiral fins are provided on the inner wall of at least a portion, preferably all, of the heat exchange tubes, wherein the rotation direction of the spiral fins on the outer wall of the heat exchange tube is the same as or opposite to the rotation direction of the spiral fins on the inner wall of the heat exchange tube, preferably opposite.

4. The reactor according to claim 3, characterized in that The spiral fins on the outer wall and / or inner wall of the heat exchange tube are protruding structures on the outer wall and / or inner wall of the heat exchange tube, wherein the cross-sectional shape of the protruding structure is a triangle, a semicircle, a semi-ellipse or a rectangle, preferably an isosceles triangle.

5. The reactor according to claim 1 or 2, characterized in that The liquid distribution device comprises a solid particle filling unit, the specifications and dimensions of each heat exchange tube are the same and are evenly 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, the diameter of the heat exchange tube is D, the cross section of the spiral fin on the outer wall of the heat exchange tube is a triangle, half of the length of the base of the triangle is h, half of the vertex angle is θ, the pitch of the spiral fin is H and the diameter of the heat exchange tube is D, the fixed bed height is l, and the heat transfer coefficient of the reactor including the liquid distribution device, the structural parameters of the spiral fins, and the heat exchange tube arrangement structural parameters satisfy the following relationship (1): In the above formula, D e Express the characteristic size in m: Re represents the Reynolds coefficient: and 0.6 < Re < 50;; α represents the heat transfer coefficient of the reactor in W / (m 2 ·K), and α > 30 W / (m 2 ·K); ρ represents the density of the reaction liquid in kg / m 3 ; μ represents the viscosity of the reaction liquid in Pa·s; u represents the flow velocity of the reaction liquid in m / s, and its calculation method is as follows: according to the predetermined liquid hourly space velocity and the volume of the catalyst loaded in the reactor, the total feed volume flow rate can be determined. The feed volume flow rate of a single repeating unit is calculated based on the number of repeating units in the catalyst loading area of the reactor, and then the feed volume flow rate of a single repeating unit is divided by the cross-sectional area of a single repeating unit is the flow rate u; W, D, H, h and l are all in units of m; θ is in radians; Pr represents the physical constant, where c p represents the constant-pressure specific heat capacity of the liquid in J / (kg·℃), λ represents the thermal conductivity of the liquid in W / (m·K); M and N are dimensionless constants, when the rotation directions of the outer wall spiral fins of all heat exchange tubes are the same, N=0.37, when the rotation directions of the outer wall spiral fins of all heat exchange tubes are opposite to the outer wall spiral fins of the adjacent heat exchange tubes, N=0.88; when the rotation direction of the outer wall spiral fins of the heat exchange tube is opposite to the rotation direction of the inner wall spiral fins of the heat exchange tube, M=1.18, and when the rotation directions are the same, M=1.

6. The reactor according to claim 1 or 2, characterized in that The liquid reaction device comprises a solid particle filling unit, the specifications and dimensions of each heat exchange tube are the same and are evenly 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, the diameter of the heat exchange tube is D, the cross section of the spiral fin of the heat exchange tube is a triangle, half of the length of the base of the triangle is h, half of the vertex angle is θ, the pitch is H and the diameter of the heat exchange tube is D, the fixed bed height is l, d is the number average diameter of the solid particles, n is the number of thread heads of the spiral fin of each heat exchange tube, and the structural parameters of the spiral fin, the structural parameters of the heat exchange tube arrangement and the pressure drop of the reactor satisfy the following relationship (2): In the above formula, D e Express the characteristic size in m: Re represents the Reynolds coefficient and such that 0.6 < Re < 50; ΔP represents the reactor pressure drop in Pa, where ΔP < 2000 kPa; ρ represents the density of the reaction liquid in kg / m 3 ³, μ represents the viscosity of the reaction liquid in Pa·s; u represents the reaction liquid flow velocity in m / s, and its calculation method is as follows: according to the predetermined liquid hourly space velocity and the volume of the catalyst loaded in the reactor, the total feed volume flow rate can be determined. The feed volume flow rate of a single repeating unit is calculated based on the number of repeating units in the catalyst loading area of the reactor, and then the feed volume flow rate of a single repeating unit is divided by the cross-sectional area of a single repeating unit That is, the flow velocity u; the unit of W, D, H, h, l and d is m; θ is measured in radians; n represents the number of thread heads of the spiral fin and is a dimensionless parameter.

7. The reactor according to any one of claims 1 to 6, characterized in that The specifications and dimensions of each heat exchange tube are the same and are evenly 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. When the side length of the square in meters is W and the diameter of the heat exchange tube in meters is D, W / D=1.2-3, preferably 1.5-2.5, and more preferably 1.8-2.

4.

8. The reactor according to any one of claims 1 to 7, characterized in that The pitches of the spiral fins on the outer wall of the heat exchange tube are equal. When the pitch of the spiral fins in m is H and the diameter of the heat exchange tube in m is D, the ratio H / D is 0.2-1.7, preferably 0.3-1.

3.

9. The reactor according to any one of claims 4 to 8, characterized in that When the cross-sectional shape of the protruding structure is a triangle, half of the base length in m of the triangle is h, and half of the vertex angle is θ, so that 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 reactor according to claim 8, characterized in that When H / D is a certain value, the outer wall spiral fins of the heat exchange tube are in a single-start thread form or a multi-start thread form, wherein the number of thread heads n of the spiral fins is greater than or equal to 1, and preferably the number of thread heads n is 2, 3 or 4.

11. The reactor according to any one of claims 1 to 10, characterized in that The reactor is a fixed bed reactor for a liquid-solid reaction system, and the solid particle filling unit is selected from a solid filler bed or a solid catalyst bed, which includes a filler or catalyst in particle form filled in the space between any two adjacent heat exchange tubes.

12. The reactor according to any one of claims 1 to 11, characterized in that The liquid distribution device also includes a liquid distributor, which is 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‰.

13. The reactor according to any one of claims 1 to 12, characterized in that The spiral fins on the outer walls of all heat exchange tubes are axially misaligned with the spiral fins on the outer walls of the adjacent heat exchange tubes by at most 1 / 3 of the pitch, preferably at most 1 / 4 of the pitch. Preferably, the spiral fins on the outer walls of all heat exchange tubes are axially distributed in mirror symmetry with the spiral fins on the outer walls of the adjacent heat exchange tubes.

14. The reactor according to any one of claims 1 to 13, characterized in that Screens are provided at both upper and lower ends of the catalyst bed, and the screen at the lower end is arranged below the bottom of the heat exchange tube.

15. The reactor according to any one of claims 1 to 14, characterized in that The heat exchange medium inlet main pipe and / or the heat exchange medium outlet main pipe of the reactor are located at the top of the reactor, and the arrangement position thereof is higher than the liquid distributor.

16. The reactor according to any one of claims 1 to 15, characterized in that The reactor is a fixed bed reactor, which 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 butanediol, etc., wherein the liquid reaction materials 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 butylene oxide and liquid water, etc., respectively. Preferably, the solid catalyst used is selected from resin.

17. A method for performing a heterogeneous catalytic reaction, characterized in that: Use of a reactor as claimed in any one of claims 1 to 16.

18. The method according to claim 17, characterized in that The method is used for preparing ethylene glycol through catalytic hydration reaction of ethylene oxide, preparing diethylene glycol through catalytic reaction of ethylene oxide and ethylene glycol, preparing triethylene glycol through catalytic reaction of ethylene oxide and diethylene glycol, preparing propylene glycol through catalytic hydration reaction of propylene oxide, or preparing butylene glycol through catalytic hydration reaction of butylene oxide.

19. The method according to claim 18, characterized in that The liquid reaction materials are liquid ethylene oxide and liquid water, and a resin is used as a solid catalyst.

20. The method according to claim 19, characterized in that At a reaction temperature of 85-150°C, a pressure of 1.0-1.8 MPa, and a reaction time of 0.5-5 h -1 Under the condition of liquid hourly space velocity, the liquid reaction material passes through the fixed bed reactor and contacts and reacts with the solid catalyst loaded between the heat exchange tubes to produce ethylene glycol.

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