Reactor for preparing dimethyl carbonate from dimethyl oxalate

Abstract

The reactor comprises a shell pass cylinder, a heat exchange tube, a lower tube box and an upper tube box, a plurality of baffle plates are fixedly connected in the shell pass cylinder, the upper end of the shell pass cylinder is fixedly connected with an upper tube plate, and the lower end of the shell pass cylinder is fixedly connected with a lower tube plate; the multiple heat exchange tubes are arranged in the shell pass barrel, the upper ends of the heat exchange tubes are fixedly connected to the upper tube plate, the lower ends of the heat exchange tubes are fixedly connected to the lower tube plate, and the heat exchange tubes are filled with catalysts; the lower tube box is detachably connected to the bottom of the lower tube plate, the upper tube box is detachably connected to the top of the upper tube plate, and the lower tube box and the upper tube box are both filled with porcelain balls. According to the invention, the contact area and the contact time of the catalyst and the reactant can be greatly increased, the reaction rate is improved, enough temperature is provided for the reactant, the reaction is more sufficient, and compared with a conventional slurry bed reactor, the slurry bed reactor is easier to industrially amplify, disassemble, assemble, repair, maintain and maintain.

Description

Technical Field

[0001] The invention relates to the technical field of reactors, in particular to a reactor for preparing dimethyl carbonate from dimethyl oxalate. Background Art

[0002] The reaction of DMO (dimethyl oxalate) decarbonylation to DMC (dimethyl carbonate) is mainly that DMO is directly decarbonylated to generate DMC under the catalysis of a catalyst. The process route of DMO decarbonylation to produce DMC is simple, with the advantages of no restrictions on raw material transportation, less three wastes, high yield, large-scale production, green environmental protection, low investment, and high economic efficiency. It is a process route that conforms to the development of modern green chemical industry.

[0003] At present, the DMO decarbonylation to DMC reactor used by domestic enterprises adopts a slurry bed reactor with stirring at the top center. The catalyst is loaded in a tube cage inserted into the reactor from the top or directly loaded in the reactor. DMO enters the decarbonylation reactor and contacts the catalyst for reaction. Because the reaction absorbs heat, multiple sets of steam plates or heating coils are additionally arranged inside the reactor to heat the reaction liquid.

[0004] The above reactor has the following problems during use:

[0005] 1. The catalyst is loaded in a catalyst cage inserted into the reactor. Due to the limited number of catalyst cages, although the agitator at the top center increases the flow rate of the internal medium, due to structural design reasons, there are still problems of small contact area and short contact time between the reaction medium and the catalyst, and the catalytic reaction effect is not good. Or the catalyst is directly loaded inside the reactor. Due to gravity, most of the catalyst will be deposited at the bottom of the reactor during stirring, and only a small amount of catalyst at the top will contact and react with the reaction liquid.

[0006] 2. Since the DMO decarbonylation to DMC reaction is endothermic, multiple sets of steam plates or heating coils are installed inside the slurry bed reactor for heating. However, due to the small internal space of the equipment, the number of steam plates or heating coils that can be installed is greatly limited, and the heat exchange area is insufficient, resulting in poor heating effect of the reaction medium, which cannot meet the heat required for the reaction and affects the reaction rate. Summary of the invention

[0007] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an embodiment of the present invention provides a reactor for preparing dimethyl carbonate from dimethyl oxalate, which can increase the reaction rate of reactants.

[0008] According to an embodiment of the present invention, a fixed bed reactor is provided, comprising: a shell-side cylinder, a heat exchange tube, a lower tube box and an upper tube box, wherein the shell-side cylinder is provided with a heat exchange cavity and a heat exchange medium inlet and a heat exchange medium outlet connected to the heat exchange cavity, wherein a plurality of baffles are fixedly connected to the heat exchange cavity, wherein the upper end of the shell-side cylinder is fixedly connected to the upper tube sheet, and the lower end of the shell-side cylinder is fixedly connected to the lower tube sheet; wherein a plurality of heat exchange tubes are provided and arranged inside the shell-side cylinder, wherein the upper end of the heat exchange tube is fixedly connected to the upper tube sheet, and the lower end of the heat exchange tube is fixedly connected to the lower tube sheet, and the interior of the heat exchange tube is filled with a catalyst; wherein the lower tube box is detachably connected to the bottom of the lower tube sheet, wherein the lower tube box is provided with a first porcelain ball cavity for filling porcelain balls and a feed port connected to the first porcelain ball cavity, and the first porcelain ball cavity is communicated with the heat exchange tube; wherein the upper tube box is detachably connected to the top of the upper tube sheet, wherein the upper tube box is provided with a second porcelain ball cavity for filling porcelain balls and a feed port connected to the second porcelain ball cavity, and the second porcelain ball cavity is communicated with the heat exchange tube.

[0009] In some embodiments, the first ceramic ball cavity and the second ceramic ball cavity are respectively filled with several layers of ceramic balls, the particle size of the ceramic balls in the first ceramic ball cavity decreases from the lower layer to the upper layer, and the particle size of the ceramic balls in the second ceramic ball cavity increases from the lower layer to the upper layer.

[0010] In some embodiments, the interior of the lower tube box is connected to an arc-shaped orifice plate at the feed inlet, the arc-shaped orifice plate is arched toward the interior of the lower tube box, and a plurality of through holes are opened on the arc-shaped orifice plate.

[0011] In some embodiments, a wire mesh is detachably connected to the outer side of the arc-shaped orifice plate, and the wire mesh is coated on the arc-shaped orifice plate. The mesh size of the wire mesh is smaller than the minimum particle size of the ceramic ball in the first ceramic ball cavity and the particle size of the catalyst in the heat exchange tube.

[0012] In some embodiments, a discharge port for discharging the reaction liquid after shutdown is provided at the bottom of the arc-shaped orifice plate.

[0013] In some embodiments, a ceramic ball pressure plate is detachably connected to the interior of the upper tube box. The ceramic ball pressure plate is disposed above the ceramic balls and presses the ceramic balls downward. The ceramic ball pressure plate has a plurality of liquid holes evenly distributed along the vertical direction.

[0014] In some embodiments, the appearance of the ceramic ball pressure plate is disc-shaped, and a plurality of grooves are evenly distributed on the outer circumference of the ceramic ball pressure plate. A plurality of card plate groups are evenly fixed on the inner wall of the upper tube box along the circumferential direction. The positions of the grooves and the card plate groups correspond and are equal in number. Each card plate group includes an upper card plate and a lower card plate corresponding to each other in the vertical direction. A space for inserting the ceramic ball pressure plate is reserved between the upper card plate and the lower card plate. The size of the groove is based on the ability to pass through the upper card plate in the vertical direction. The ceramic ball pressure plate is clamped between the upper card plate and the lower card plate by rotation.

[0015] In some embodiments, a handle is fixedly connected to the top of the ceramic ball pressure plate.

[0016] In some embodiments, the upper end of the upper tube box is detachably fixedly connected to the upper head via a flange. The upper head has an insertion port for a temperature measuring tube. The insertion port for the temperature measuring tube is vertically aligned with the heat exchange tube so that the temperature measuring tube can be inserted into the heat exchange tube for temperature monitoring. Sockets for the temperature measuring tube to pass through are provided at corresponding positions of the flange, the porcelain ball pressure plate and the upper tube plate.

[0017] Another aspect of the present invention provides an embodiment of the present invention that provides an application of the fixed bed reactor in the preparation of dimethyl carbonate from dimethyl oxalate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings.

[0019] in:

[0020] Figure 1 This is a schematic diagram of the structure of a reactor for preparing dimethyl carbonate from dimethyl oxalate in an embodiment of the present invention;

[0021] Figure 2 for Figure 1 An enlarged schematic diagram of part A in FIG.

[0022] Figure 3 for Figure 1 An enlarged schematic diagram of part B in FIG.

[0023] Figure 4 for Figure 1 Schematic diagram of the use of the ceramic ball pressure plate;

[0024] Figure 5 for Figure 1 A schematic diagram of the structure of the porcelain ball pressure plate;

[0025] Figure 6 for Figure 5 A top view of

[0026] Figure 7 The figure is a schematic diagram of the arrangement of the liquid holes of the ceramic ball pressure plate;

[0027] Figure 8 This is a top view of the ceramic ball pressing plate when in use;

[0028] Fig. 9 for Figure 1 Schematic diagram of the structure of the arc orifice plate;

[0029] Fig.10 Schematic diagram of the arrangement of through holes of the arc-shaped orifice plate;

[0030] Reference numerals:

[0031] 1. Upper head; 2. Upper tube box; 3. Ceramic ball pressure plate; 301. Handle; 302. Groove; 4. Ceramic ball; 5. Upper tube sheet; 6. Shell-side cylinder; 7. Lower tube sheet; 8. Lower tube box; 9. Arc orifice plate; 901. Material withdrawal port; 10. Support leg; 11. Lifting ear; 12. Baffle; 13. Heat exchange tube; 14. Upper clamping plate; 15. Lower clamping plate; 16. Wire mesh. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0033] The following describes a reactor for preparing dimethyl carbonate from dimethyl oxalate according to an embodiment of the present invention with reference to the accompanying drawings.

[0034] like Figure 1-10 As shown, an embodiment of the present invention provides a fixed bed reactor, comprising: a shell-side barrel 6, a heat exchange tube 13, a lower tube box 8 and an upper tube box 2, wherein the shell-side barrel 6 has a heat exchange cavity and a heat exchange medium inlet and a heat exchange medium outlet connected to the heat exchange cavity, and a plurality of baffles 12 are fixedly connected to the heat exchange cavity, the upper end of the shell-side barrel 6 is fixedly connected to the upper tube sheet 5, and the lower end of the shell-side barrel 6 is fixedly connected to the lower tube sheet 7; a plurality of heat exchange tubes 13 are provided and arranged inside the shell-side barrel 6, and the upper ends of the heat exchange tubes 13 are fixedly connected to the upper tube sheet 5. Plate 5, the lower end of the heat exchange tube 13 is fixedly connected to the lower tube plate 7, and the interior of the heat exchange tube 13 is filled with a catalyst; the lower tube box 8 is detachably connected to the bottom of the lower tube plate 7, and the lower tube box 8 has a first porcelain ball cavity for filling porcelain balls 4 and a feed port connected to the first porcelain ball cavity, and the first porcelain ball cavity is connected to the heat exchange tube 13; the upper tube box 2 is detachably connected to the top of the upper tube plate 5, and the upper tube box 2 has a second porcelain ball cavity for filling porcelain balls 4 and a discharge port connected to the second porcelain ball cavity, and the second porcelain ball cavity is connected to the heat exchange tube 13.

[0035] The embodiment of the present invention can greatly increase the contact area and contact time between the catalyst and the reactants and improve the reaction rate by providing a plurality of heat exchange tubes 13 in the shell-side cylinder 6. By providing a baffle 12 in the shell-side cylinder 6, the steam in the shell-side cylinder 6 can be deflected multiple times between the baffles 12, thereby lengthening the flow path of the steam, increasing the contact time between the steam and the heat exchange tube 13, achieving cross-flow heat exchange between the steam and the heat exchange tube 13, and enhancing the heat exchange effect, thereby providing sufficient temperature for the reactants and making the reaction more sufficient. The reactor of the embodiment of the present invention is a fixed bed reactor, which is easier to scale up industrially and easier to disassemble, overhaul, maintain and service than a conventional slurry bed reactor.

[0036] It should be noted that the main form of the reactor is a vertical shell and tube fixed tube sheet reactor. The reaction material enters from the bottom of each heat exchange tube 13 after passing through the porcelain ball 4. Under the action of the catalyst, a chemical reaction occurs inside each heat exchange tube 13. At the same time, since the heat exchange tube 13 is vertically arranged and has a long length, some of which can even reach more than 6 meters, the reaction material has sufficient time to contact with the catalyst inside the heat exchange tube 13 to react chemically. Compared with the original reactor, the contact area between the reaction material and the catalyst is larger, the contact time is longer, and the reaction effect is better.

[0037] Since the reaction in the heat exchange tube 13 is an endothermic reaction, the heat demand is very large. The reactor of the present invention evenly distributes the chemical reaction inside each thin-walled heat exchange tube 13, and the outside of each heat exchange tube 13 is evenly in contact with the steam heat source. Since the number of heat exchange tubes 13 is large and the cumulative heat exchange area is large, compared with the original reactor, the heat absorption effect of the reaction material is better, and a better chemical reaction effect can be achieved.

[0038] The embodiment of the present invention provides a plurality of baffles 12 in the heat exchange chamber to form a baffle structure in the heat exchange chamber, thereby improving the heat exchange efficiency between the reaction liquid and the heat exchange medium, providing a sufficient temperature for the reaction of the reaction liquid, and further improving the reaction rate of the reaction liquid.

[0039] Furthermore, a level gauge and a pressure sensor are connected inside the shell side cylinder 6 to monitor the level and pressure of the heat exchange medium in the heat exchange cavity in real time, and to achieve accurate perception and control of the reaction process through real-time monitoring and timely feedback. There are four level gauges, and they are located in different positions, which can make the monitoring value more accurate.

[0040] Furthermore, the upper tube box 2 and the upper tube sheet 5 are detachably connected by bolts, the lower tube box 8 and the lower tube sheet 7 are detachably connected by bolts, and the shell-side cylinder 6 is connected to the upper tube sheet 5 and the lower tube sheet 7 by welding.

[0041] Furthermore, the heat exchange medium is steam, the heat exchange medium inlet is a steam inlet, and the heat exchange medium outlet is a condensate outlet.

[0042] Furthermore, the heat exchange tube 13 is connected to the lower tube sheet 7 and the upper tube sheet 5 as a whole by welding and expansion. The interior of each heat exchange tube 13 is filled with catalyst.

[0043] In some embodiments, Figure 1-3 As shown, the first ceramic ball cavity and the second ceramic ball cavity are respectively filled with several layers of ceramic balls 4, the particle size of the ceramic balls 4 in the first ceramic ball cavity decreases from the lower layer to the upper layer, and the particle size of the ceramic balls 4 in the second ceramic ball cavity increases from the lower layer to the upper layer.

[0044] By designing the ceramic ball layer in this way, ceramic balls with smaller particle sizes are arranged near the catalyst, which can prevent the catalyst from entering the ceramic ball layer of the upper tube box 2 and the lower tube box 8. The ceramic balls 4 with larger particle sizes are arranged at a position far away from the catalyst, and the gap between the ceramic balls 4 is increased, which is conducive to the reaction liquid entering the heat exchange tube 13 from the bottom, and is conducive to the upward discharge of the reaction product. In addition, the arrangement of multiple layers of ceramic balls can also improve the dispersion effect on the reaction liquid and the buffering effect when the reaction liquid is fed.

[0045] Furthermore, the first ceramic ball cavity is provided with four layers of ceramic balls 4, and the particle sizes of the ceramic balls 4 in the ceramic ball layer are 25 mm, 13 mm, 6 mm and 3 mm respectively from bottom to top. The second ceramic ball cavity is provided with two layers of ceramic balls 4, and the particle size of the ceramic balls 4 in the lower ceramic ball layer is 3 mm, and the particle size of the ceramic balls 4 in the upper ceramic ball layer is 6 mm.

[0046] In some embodiments, Fig. 9 As shown, the lower tube box 8 is connected to an arc-shaped orifice plate 9 at the feed port, the arc-shaped orifice plate 9 is arched toward the inside of the lower tube box 8, and a plurality of through holes are opened on the arc-shaped orifice plate 9. The arrangement of the through holes is not limited to Fig.10 The arrangement shown.

[0047] The embodiment of the present invention can prevent the ceramic balls 4 or catalyst from blocking the feed port while allowing the reaction liquid to pass through by providing the arc-shaped orifice plate 9. The arc-shaped orifice plate 9 is arched toward the inside of the lower tube box 8, that is, arched upward, and can withstand the gravity of the ceramic balls 4, playing a role of bearing pressure.

[0048] Furthermore, the bottom of the lower tube box 8 is an arc-shaped bottom that bulges downward, and the feed port is located at the bottom center of the lower tube box 8 .

[0049] In some embodiments, Fig. 9 As shown, the outer side of the arc-shaped orifice plate 9 is detachably connected with a wire mesh 16, which is coated on the arc-shaped orifice plate 9, and the mesh size of the wire mesh 16 is smaller than the minimum particle size of the ceramic ball 4 in the first ceramic ball cavity and the particle size of the catalyst in the heat exchange tube 13. The ceramic ball 4 or the catalyst can be prevented from entering the feed port.

[0050] It should be noted that, in actual use, a wire mesh is usually used to prevent the ceramic balls 4 or catalysts from entering the feed port, and the aperture of the through hole of the arc-shaped orifice plate 9 is usually larger than the particle size of the ceramic balls 4 or the catalyst. This is because the smaller the aperture of the through hole, the greater the resistance to the reaction liquid, thereby affecting the smooth flow of the reaction liquid.

[0051] Furthermore, the wire mesh 16 is provided with two layers.

[0052] Further, the detachable connection mode of the wire mesh 16 can be a conventional connection mode such as bolt connection, snap connection, etc. In addition, the wire mesh 16 can also be connected to the arc-shaped orifice plate 9 by welding.

[0053] Furthermore, the material of the screen 16 is S30408.

[0054] In some embodiments, Fig. 9 As shown, a material withdrawal port 901 for withdrawing the reaction liquid after shutdown is provided at the bottom of the arc-shaped orifice plate 9 .

[0055] Furthermore, four material return ports 901 are evenly distributed along the lower edge of the arc-shaped orifice plate 9 .

[0056] In some embodiments, Figure 4-8 As shown, the upper tube box 2 is detachably connected to a ceramic ball pressing plate 3, which is arranged above the ceramic ball 4 and presses the ceramic ball 4 downward. The ceramic ball pressing plate 3 is evenly distributed with a plurality of liquid holes along the vertical direction. The arrangement of the liquid holes is not limited to Figure 7 The arrangement shown.

[0057] The embodiment of the present invention can effectively prevent the catalyst and the ceramic balls 4 from being flushed into the production system due to excessive pressure of the bottom liquid during the operation of the equipment by providing the ceramic ball pressing plate 3.

[0058] In some embodiments, Figure 4-8 As shown, the shape of the porcelain ball pressing plate 3 is disc-shaped, and a plurality of grooves 302 are evenly distributed on the outer circumference of the porcelain ball pressing plate 3. A plurality of cardboard groups are evenly fixed on the inner wall of the upper tube box 2 along the circumferential direction. The grooves 302 correspond to the positions of the cardboard groups and are equal in number. Each cardboard group includes an upper cardboard 14 and a lower cardboard 15 corresponding to each other in the vertical direction. A space for inserting the porcelain ball pressing plate 3 is reserved between the upper cardboard 14 and the lower cardboard 15. The size of the groove 302 is based on the size that can pass through the upper cardboard 14 in the vertical direction. The porcelain ball pressing plate 3 is clamped between the upper cardboard 14 and the lower cardboard 15 by rotation. The porcelain ball pressing plate 3 can be quickly disassembled and assembled.

[0059] Furthermore, there are four grooves 302 and four clamping plate groups.

[0060] When in use, the four grooves 302 of the ceramic ball pressing plate 3 are aligned with the upper clamping plate 14 in the vertical direction, so that the ceramic ball pressing plate 3 passes through the upper clamping plate 14 from top to bottom, and then the ceramic ball pressing plate 3 is rotated to stagger the positions of the upper clamping plate 14 and the grooves 302, so that the ceramic ball pressing plate 3 is clamped between the upper clamping plate 14 and the lower clamping plate 15. When the ceramic ball pressing plate 3 needs to be removed, the ceramic ball pressing plate 3 is rotated to align the grooves 302 of the ceramic ball pressing plate 3 with the upper clamping plate 14, and the ceramic ball pressing plate 3 is lifted upward to remove the ceramic ball pressing plate 3.

[0061] Furthermore, the upper clamping plate 14 and the lower clamping plate 15 are both arranged horizontally, and the projection area of ​​the lower clamping plate 15 in the vertical direction is larger than the projection area of ​​the upper clamping plate 14 in the vertical direction, which can improve the supporting force of the lower clamping plate 15 on the ceramic ball pressing plate 3.

[0062] In some embodiments, Figure 5 As shown, a handle 301 is fixedly connected to the top of the porcelain ball pressing plate 3. The porcelain ball pressing plate 3 can be rotated by rotating the handle 301, so that the porcelain ball pressing plate 3 can be disassembled and assembled on the inner wall of the upper tube box 2.

[0063] In some embodiments, Figure 2 As shown, the upper end of the upper tube box 2 is detachably fixedly connected to the upper head 1 via a flange. The upper head 1 has an insertion port for a temperature measuring tube. The insertion port for the temperature measuring tube is vertically aligned with the heat exchange tube 13 so that the temperature measuring tube can be inserted into the heat exchange tube 13 for temperature monitoring. Sockets for the temperature measuring tube to pass through are provided at corresponding positions of the flange, the porcelain ball pressure plate 3 and the upper tube plate 5.

[0064] The embodiment of the present invention provides a detachably connected upper head 1 to facilitate the loading of the catalyst and the ceramic balls 4. By inserting the temperature measuring tube into the heat exchange tube 13, the temperature of the reaction material can be monitored in real time, and accurate perception and control of the reaction process can be achieved.

[0065] Furthermore, there are two temperature measuring tube insertion ports located at different positions, which can make the monitoring value more accurate.

[0066] Furthermore, the upper end cap 1 has a gas phase outlet pipe and two pressure measuring pipes, the gas phase outlet pipe is used to discharge pressure, and the pressure measuring pipe is used to insert a pressure measuring pipe to monitor the internal pressure of the upper pipe box 2. The side of the upper pipe box 2 has a temperature measuring pipe for monitoring the temperature inside the upper pipe box 2.

[0067] Furthermore, the upper portion of the temperature measuring tube is connected to the temperature measuring tube insertion port of the upper head 1 by bolts.

[0068] In some embodiments, Figure 3 As shown, the outer sides of the upper tube box 2 and the lower tube box 8 are respectively fixedly connected with lifting ears 11 for lifting, and the bottom of the lower tube box 8 is fixedly connected with a supporting leg 10.

[0069] In the embodiment of the present invention, the upper tube box 2 and the lower tube box 8 are provided with lifting ears 11, so as to facilitate the lifting of the upper tube box 2 and the lower tube box 8. The supporting legs 10 are provided at the bottom of the lower tube box 8, so as to stably support the whole reactor.

[0070] Another aspect of the present invention is to provide an application of the fixed bed reactor in preparing dimethyl carbonate from dimethyl oxalate. The fixed bed reactor of the present invention can be used not only in preparing dimethyl carbonate from dimethyl oxalate, but also in other fields, such as chemical industry, biomedicine, etc.

[0071] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0072] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0073] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0074] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0075] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0076] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A fixed bed reactor, characterized in that: include: A shell-side cylinder, wherein the shell-side cylinder has a heat exchange cavity and a heat exchange medium inlet and a heat exchange medium outlet connected to the heat exchange cavity, a plurality of baffles are fixedly connected to the heat exchange cavity, the upper end of the shell-side cylinder is fixedly connected to an upper tube sheet, and the lower end of the shell-side cylinder is fixedly connected to a lower tube sheet; A heat exchange tube, wherein a plurality of heat exchange tubes are provided and arranged inside the shell-side cylinder, the upper end of the heat exchange tube is fixedly connected to the upper tube sheet, the lower end of the heat exchange tube is fixedly connected to the lower tube sheet, and the interior of the heat exchange tube is filled with a catalyst; A lower tube box, the lower tube box is detachably connected to the bottom of the lower tube plate, the lower tube box has a first porcelain ball cavity for filling porcelain balls and a feed port connected to the first porcelain ball cavity, and the first porcelain ball cavity is connected to the heat exchange tube; An upper tube box is detachably connected to the top of the upper tube plate, and has a second ceramic ball cavity for filling the ceramic balls and a discharge port connected to the second ceramic ball cavity, wherein the second ceramic ball cavity is connected to the heat exchange tube.

2. The fixed bed reactor according to claim 1, characterized in that The first ceramic ball cavity and the second ceramic ball cavity are respectively filled with several layers of the ceramic balls. The particle size of the ceramic balls in the first ceramic ball cavity decreases from the lower layer to the upper layer, and the particle size of the ceramic balls in the second ceramic ball cavity increases from the lower layer to the upper layer.

3. The fixed bed reactor according to claim 1, characterized in that The interior of the lower tube box is connected with an arc-shaped orifice plate at the feed inlet, the arc-shaped orifice plate arches toward the interior of the lower tube box, and a plurality of through holes are formed on the arc-shaped orifice plate.

4. The fixed bed reactor according to claim 3, characterized in that A wire mesh is detachably connected to the outer side of the arc-shaped orifice plate, and the wire mesh is coated on the arc-shaped orifice plate. The mesh size of the wire mesh is smaller than the minimum particle size of the ceramic ball in the first ceramic ball cavity and the particle size of the catalyst in the heat exchange tube.

5. The fixed bed reactor according to claim 3, characterized in that: A material withdrawal port for withdrawing the reaction liquid after shutdown is provided at the bottom of the arc-shaped orifice plate.

6. The fixed bed reactor according to claim 1, characterized in that A ceramic ball pressing plate is detachably connected to the interior of the upper tube box. The ceramic ball pressing plate is arranged above the ceramic balls and presses the ceramic balls downwards. The ceramic ball pressing plate is provided with a plurality of liquid holes evenly distributed along the vertical direction.

7. The fixed bed reactor according to claim 6, characterized in that The appearance of the ceramic ball pressure plate is disc-shaped, and a plurality of grooves are evenly distributed on the outer circumference of the ceramic ball pressure plate. A plurality of card plate groups are evenly fixed on the inner wall of the upper tube box along the circumferential direction. The grooves correspond to the positions of the card plate groups and are equal in number. Each of the card plate groups includes an upper card plate and a lower card plate corresponding to each other in the vertical direction. A space for inserting the ceramic ball pressure plate is reserved between the upper card plate and the lower card plate. The size of the groove is based on the ability to pass through the upper card plate in the vertical direction. The ceramic ball pressure plate is clamped between the upper card plate and the lower card plate by rotation.

8. The fixed bed reactor according to claim 6, characterized in that A handle is fixedly connected above the ceramic ball pressing plate.

9. The fixed bed reactor according to claim 6, characterized in that: The upper end of the upper tube box is detachably fixedly connected to the upper head via a flange, and the upper head has an insertion port for a temperature measuring tube, which is vertically aligned with the heat exchange tube so that the temperature measuring tube can be inserted into the heat exchange tube for temperature monitoring, and corresponding positions of the flange, the porcelain ball pressure plate and the upper tube plate are provided with insertion holes for the temperature measuring tube to pass through.

10. Use of the fixed bed reactor according to any one of claims 1 to 9 in preparing dimethyl carbonate from dimethyl oxalate.

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