Reaction kettle for preparing oxalic acid

Abstract

The utility model relates to the field of chemical industry, in particular to a reaction kettle for preparing oxalic acid, which comprises an upper cover, a barrel bottom and a plurality of barrels, a material circulating pipe is arranged between the upper cover and the barrel bottom, a heat exchanger is arranged in the middle of the material circulating pipe, and an air outlet pipe is arranged at the top of the upper cover; compared with a mode of directly gushing from the bottom, when airflow entering the inner side of the barrel is sprayed out from the air outlet direction of the movable floating pipe, due to the fact that the air outlet of the movable floating pipe is close to the inner wall of the barrel and is matched with the radian of the interior of the barrel, after the blowing-out direction of the airflow is controlled, materials in the barrel can rotate to form vortexes, and the vortex effect is improved. A plurality of movable floating pipes can push the materials to rotate at multiple heights in the materials at the same time, so that the materials are stirred more uniformly.

Description

Technical Field

[0001] The utility model relates to the field of chemical industry, in particular to a reaction kettle for preparing oxalic acid. Background Art

[0002] Oxalic acid is an organic substance and a metabolite of organisms. It is a medium-strong acid widely distributed in plants, animals and fungi, and plays different functions in different life forms. Studies have found that more than 100 plants are rich in oxalic acid, especially spinach, amaranth, beet, purslane, taro, sweet potato and rhubarb. Since oxalic acid can reduce the bioavailability of mineral elements, it easily forms calcium oxalate with calcium ions in the human body to cause kidney stones, so oxalic acid is often considered to be an antagonist of mineral element absorption and utilization. The main industrial production methods of oxalic acid are: sodium formate method, oxidation method, carbonyl synthesis method, ethylene glycol oxidation method, propylene oxidation method, and carbon monoxide coupling method. Among them, the oxidation method: using starch or glucose mother liquor as raw material, in the presence of alum catalyst, it undergoes oxidation reaction with nitric acid-sulfuric acid to obtain oxalic acid, and the nitrogen oxides in the exhaust gas are sent to the absorption tower for recovery to generate dilute nitric acid.

[0003] Oxalic acid is mainly used in the production of drugs such as antibiotics and borneol, as well as solvents for refining rare metals, dye reducing agents, tanning agents, etc. In addition, oxalic acid can also be used to synthesize various oxalic acid esters, oxalates, and oxalamides, with diethyl oxalate, sodium oxalate, and calcium oxalate having the largest output. Oxalic acid can also be used in the production of cobalt-molybdenum-aluminum catalysts, cleaning of metals and marble, and bleaching of textiles. It is used as an acidity regulator for synthesizing adhesives such as urea-formaldehyde resins and melamine formaldehyde resins. It is used in the pharmaceutical industry to manufacture drugs such as oxytetracycline and chlortetracycline.

[0004] Prior art, such as publication number: CN202238059U, discloses a reactor for the oxidation synthesis process in the production of industrial oxalic acid. In order to solve the problem of high temperature and strong corrosiveness of the materials involved in the traditional industrial oxalic acid production, the inner wall is generally made of corrosion-resistant enamel or polytetrafluoroethylene material production equipment. Due to the limitation of its materials, and the use of fixed stirring, external oxygenation and interlayer cooling, the volume of the traditional reactor is relatively small, and the maximum volume is less than 20m3. This leads to the use of multiple reactors in the production of industrial oxalic acid, which occupies a large area and becomes a bottleneck problem in the large-scale production of oxalic acid. The originally integrated reactor is divided into a detachable upper cover, a cylinder and a cylinder bottom, wherein the number of cylinders is increased as needed to adjust the volume as needed, wherein the polytetrafluoroethylene lining layer is resistant to high temperature and corrosion, meets the requirements of oxalic acid production, and has automatic cooling, oxygenation and cyclone stirring.

[0005] In the above-mentioned prior art, an air inlet pipe and an exhaust pipe are respectively arranged between the bottom of the cylinder and the upper cover, and oxygen is pumped in from the bottom of the cylinder. The remaining gas is recently discharged from the corresponding air outlet pipe of the upper cover after being absorbed by the material. A cyclone stirring method is adopted in the process to help save the space required for installing a fixed stirring device in the cylinder. However, there is still room for improvement in the cyclone stirring process. For this reason, we propose a reactor for preparing oxalic acid. Utility Model Content

[0006] The utility model aims to provide a reaction kettle for preparing oxalic acid to solve the problems raised in the above background technology.

[0007] To achieve the above object, a reaction kettle for preparing oxalic acid is provided, which is composed of an upper cover, a cylinder bottom and a plurality of cylinders, a material circulation pipe is arranged between the upper cover and the cylinder bottom, a heat exchanger is arranged in the middle of the material circulation pipe, and an air outlet pipe is arranged on the top of the upper cover;

[0008] The outer wall of the cylinder is fixedly connected with a connecting pipe, and both ends of the connecting pipe extend to the inner and outer ends of the cylinder respectively. The end of the connecting pipe located on the inner side of the cylinder is provided with an air supply mechanism, and the air supply mechanism is used to adapt to the liquid level height in the cylinder and control the airflow to blow toward the inner wall of the cylinder. The end of the connecting pipe located on the outer side of the cylinder is provided with an air separation mechanism that can adapt to the height of the reactor.

[0009] Among them, the air supply mechanism includes a movable float tube, which is vertically movably connected to the lower end of the connecting pipe, a compartment cavity is provided on the lower side of the inner wall of the connecting pipe, a one-way valve A is provided on the upper side of the compartment cavity inside the connecting pipe, one end of the movable float tube extending into the compartment cavity is fixedly connected to a vertical cylinder, and the top of the vertical cylinder is fixedly connected to a convex ring whose size matches that of one end of the one-way valve A.

[0010] On the basis of the above-mentioned solution, a one-way valve B is provided inside the movable floating tube near the lower side, and a downward folding angle is provided near the air flow outlet of the movable floating tube.

[0011] As a further solution of the utility model, the gas distribution mechanism includes a connecting pipe, one end of the connecting pipe is threadedly connected to one end of the connecting pipe located on the outside of the cylinder, and the other end of the connecting pipe is rotatably connected to the outer wall of the upper box, the middle box or the bottom box, and the total number of the upper box, the middle box and the bottom box is adapted to the number of the cylinders.

[0012] On the basis of the above scheme, the height of the middle box is adapted to the height of the cylinder, the upper and lower surfaces of the middle box are respectively provided with plug-ins and slots of matching sizes, and the lower surface of the upper box and the upper surface of the bottom box are provided with slots and plug-ins that are adapted to the size of the middle box.

[0013] Based on the above scheme, a protrusion is provided outwardly on the bottom of the inner wall of the bottom box away from the cylinder body, and an air inlet pipe with an air outlet direction vertically upward is fixedly installed below the protrusion on the lower surface of the bottom box.

[0014] Preferably, a boss is provided on the lower surface of the upper cover and the lower surface of the cylinder near the bottom edge of the inner wall, and a groove with a matching size is provided on the upper surface of the cylinder and the cylinder bottom corresponding to the boss.

[0015] Preferably, the outer wall of the cylinder is fixedly connected with a convex ring near the top and the bottom, and the surface of the convex ring is provided with a plurality of vertical and evenly distributed screw holes.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] 1. In the utility model, compared with the method of directly gushing from the bottom, when the airflow entering the inner side of the cylinder is ejected from the outlet direction of the movable floating tube, since the outlet of the movable floating tube is close to the inner wall of the cylinder and is adapted to the internal curvature of the cylinder at that location, after controlling the blowing direction of the airflow, it is helpful for the material in the cylinder to rotate to form a vortex, driving the internal material to be fully stirred. Several movable floating tubes can be at multiple heights inside the material, and at the same time, they can drive the material to rotate, making the stirring more uniform;

[0018] 2. Since the material in the kettle is not at the maximum height for a long time, when the liquid level is greatly reduced, in order to avoid the waste of oxygen blown out from the air inlet pipe, when the movable float pipe is immersed in the material, it floats up due to the buoyancy of the material, causing the convex ring to rise in the compartment. The convex ring lifts the valve cover on the one-way valve A inside the connecting pipe through the one-way valve B, so that the oxygen transported from the connecting pipe can enter the movable float pipe. Similarly, when the material does not reach the corresponding height, the airflow blown from the connecting pipe will prompt the one-way valve A to close, so that the airflow outlet is only located in the material;

[0019] 3. After the airflow is blown out, it contacts the inner wall of the protrusion. After overflowing, it enters the movable floating tube from the connecting space between the upper box, the middle box and the bottom box along the connecting pipe and the connecting pipe, so that the air pressure between the several boxes is balanced for a longer time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic elevation diagram of a reaction kettle for preparing oxalic acid according to the utility model;

[0021] Figure 2 This is a schematic top view of the interior of a reactor for preparing oxalic acid in the utility model;

[0022] Figure 3 This is a schematic diagram of the inner side cross-section of a single cylinder in a reaction kettle for preparing oxalic acid according to the utility model;

[0023] Figure 4It is a partially enlarged schematic diagram of a reaction kettle for preparing oxalic acid in the utility model.

[0024] In the figure: 1. upper cover; 2. cylinder bottom; 3. cylinder body; 4. material circulation pipe; 5. air outlet pipe; 6. connecting pipe; 7. air supply mechanism; 8. air distribution mechanism; 9. movable floating tube; 10. partition chamber; 11. one-way valve A; 12. vertical cylinder; 13. convex ring; 14. one-way valve B; 15. connecting pipe; 16. upper box; 17. middle box; 18. bottom box; 19. air inlet pipe; 20. boss. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] Example 1

[0027] See also Figure 1-4 , the figure shows a preferred embodiment of the utility model, a reactor for preparing oxalic acid, which is composed of an upper cover 1, a cylinder bottom 2 and a plurality of cylinders 3, a material circulation pipe 4 is arranged between the upper cover 1 and the cylinder bottom 2, a heat exchanger is arranged in the middle of the material circulation pipe 4, and an air outlet pipe 5 is arranged on the top of the upper cover 1;

[0028] The outer wall of the cylinder 3 is fixedly connected with a connecting pipe 6, and both ends of the connecting pipe 6 extend to the inner and outer ends of the cylinder 3 respectively. The outer end of the connecting pipe 6 is connected with the air inlet pipe 19, and the end of the connecting pipe 6 located on the inner side of the cylinder 3 is provided with an air supply mechanism 7. The air supply mechanism 7 is used to adapt to the liquid level in the cylinder 3 and control the airflow to blow toward the inner wall of the cylinder 3; through the air supply mechanism 7, the oxygen blown into the air inlet pipe 19 is transported to below the material liquid level as much as possible, and by controlling the blowing direction of the airflow, it helps the material in the cylinder 3 to rotate to form a vortex, thereby driving the internal material to be fully stirred.

[0029] It can be understood that the air supply mechanism 7 includes a movable floating tube 9, which is vertically and movably connected to the lower end of the connecting tube 6, a compartment 10 is provided on the lower side of the inner wall of the connecting tube 6, and a one-way valve A11 is provided on the upper side of the compartment 10 inside the connecting tube 6, and one end of the movable floating tube 9 extending into the compartment 10 is fixedly connected to a vertical cylinder 12, and the top of the vertical cylinder 12 is fixedly connected to a convex ring 13 whose size matches that of one end of the one-way valve A11; it should be supplemented that vertical bars and corresponding ones are provided between the outer side of the movable floating tube 9 and the lower end of the connecting tube 6 A vertical groove should be formed to ensure that the movable float tube 9 is on the lower side of the connecting pipe 6 and can only rise and fall vertically without rotating. When the movable float tube 9 is immersed in the material, it floats up due to the buoyancy of the material, causing the convex ring 13 to rise in the compartment 10. The convex ring 13 lifts the valve cover on the one-way valve A11 inside the connecting pipe 6 through the one-way valve B14, so that the oxygen transported from the connecting pipe 6 can enter the movable float tube 9. Similarly, when the material does not reach the corresponding height, the airflow blown from the connecting pipe 6 will prompt the one-way valve A11 to close, so that the airflow outlet is only located in the material.

[0030] Specifically, a one-way valve B14 is provided inside the movable floating tube 9 near the lower side, and a downward folded angle is provided near the airflow outlet of the movable floating tube 9; this folded angle can help the one-way valve B14 retain part of the gas after the airflow stops blowing out, and cooperate with the vertical tube 12 to prevent materials from flowing into the deep part of the movable floating tube 9.

[0031] It can be understood that a boss 20 is provided on the lower surface of the upper cover 1 and the lower surface of the cylinder 3 near the bottom edge of the inner wall, and a groove of matching size is provided on the upper surface of the cylinder 3 and the cylinder bottom 2 at the position corresponding to the boss 20, wherein the boss 20 and the corresponding groove can help the upper cover 1, the cylinder bottom 2 and the cylinder 3 to align naturally after they are roughly aligned when the upper cover 1, the cylinder bottom 2 and the cylinder 3 are hoisted.

[0032] Among them, the outer wall of the cylinder 3 is fixedly connected with a convex ring near the top and the bottom, and the surface of the convex ring is provided with a plurality of vertical and evenly distributed screw holes. The upper cover 1, the cylinder bottom 2 and the cylinder 3 are fixed by bolts at the screw holes of the convex ring.

[0033] In this embodiment, when the reactor is installed, the required volume is adapted by adjusting the number of cylinders 3. On the basis of the prior art, the airflow entering the inner side of the cylinder 3 is ejected from the outlet direction of the movable floating tube 9, compared with the method of directly ejecting from the bottom. Since the outlet of the movable floating tube 9 is close to the inner wall of the cylinder 3 and adapted to the internal curvature of the cylinder 3 at that location, after controlling the blowing direction of the airflow, it is helpful for the material in the cylinder 3 to rotate to form a vortex, driving the internal material to be fully stirred. A plurality of movable floating tubes 9 can be at multiple heights inside the material, and at the same time, the material is driven to rotate, so that the stirring is more uniform.

[0034] Normally, since the material in the kettle is not at the maximum height for a long time, when the liquid level is greatly reduced, in order to avoid the waste of oxygen blown out from the air inlet pipe 19, the movable floating pipe 9 is immersed in the material and floats up under the influence of the buoyancy of the material, so that the convex ring 13 rises in the compartment 10. The convex ring 13 lifts the valve cover on the one-way valve A11 inside the connecting pipe 6 through the one-way valve B14, so that the oxygen transported from the connecting pipe 6 can enter the movable floating pipe 9. Similarly, when the material does not reach the corresponding height, the airflow blown from the connecting pipe 6 will prompt the one-way valve A11 to close, so that the airflow outlet is only located in the material.

[0035] It should be added that the oxygen transported inside the air inlet pipe 19 is pressurized by pumping and enters the connecting pipe 6. The material in the kettle is pumped out from the bottom center of the cylinder 3 through the material circulation pipe 4 and returns to the cylinder 3 from the top of the upper cover 1. The heat is dissipated through the heat exchanger during the process. During the process, since the discharge port is located at the bottom center of the cylinder 3, it will not cause too much impact on the vortex formed by the airflow blown out of the movable floating tube 9.

[0036] Example 2

[0037] See also Figure 1-3 , the figure shows a preferred embodiment of the utility model, a reactor for preparing oxalic acid, which is different from Example 1 in that a gas separation mechanism 8 which can adapt to the height of the reactor is provided at one end of the connecting pipe 6 located outside the cylinder 3.

[0038] As a further solution of the utility model, the gas distribution mechanism 8 includes a connecting pipe 15, one end of the connecting pipe 15 is threadedly connected to the end of the connecting pipe 6 located on the outside of the cylinder 3, and the other end of the connecting pipe 15 is rotatably connected to the outer wall of the upper box 16, the middle box 17 or the bottom box 18. The total number of the upper box 16, the middle box 17 and the bottom box 18 is adapted to the number of the cylinders 3; in the same way as the volume adjustment method of the reactor, during installation, by adjusting the number of the middle boxes 17, it is convenient to supply gas to the outside of all the cylinders 3.

[0039] Specifically, the height of the middle box 17 is adapted to the height of the cylinder 3, and the upper and lower surfaces of the middle box 17 are respectively provided with plug-ins and slots of matching sizes, and the lower surface of the upper box 16 and the upper surface of the bottom box 18 are provided with slots and plug-ins that are adapted to the size of the middle box 17. Before installation, the upper box 16, middle box 17 and bottom box 18 to be installed can be correspondingly plugged and assembled together, and after approaching the connecting pipe 6, the connecting pipe 15 can be rotated to complete the installation.

[0040] It can be understood that in order to avoid direct airflow, which would lead to uneven air pressure distribution among several connecting pipes 6, a protrusion is provided outwardly on the bottom of the inner wall of the bottom box 18 away from the side of the cylinder 3, and an air inlet pipe 19 with an air outlet direction vertically upward is fixedly installed below the protrusion on the lower surface of the bottom box 18. After the airflow is blown out, it contacts the inner wall of the protrusion, and after overflowing, it enters the movable floating tube 9 along the connecting pipe 15 and the connecting pipe 6 from the connecting space between the upper box 16, the middle box 17 and the bottom box 18.

[0041] In this embodiment, during installation, by adjusting the number of middle boxes 17, it is convenient to supply air simultaneously on the outside of several connecting pipes 6. Before installation, the upper box 16, middle box 17 and bottom box 18 to be installed can be correspondingly plugged and assembled together. After approaching the connecting pipe 6, the connecting pipe 15 can be rotated to complete the installation.

[0042] The above content is a further detailed description of the utility model in combination with specific implementation methods. It cannot be determined that the specific implementation of the utility model is limited to these descriptions. For ordinary technicians in the technical field to which the utility model belongs, without departing from the concept of the utility model, they can also make several simple deductions or substitutions, which should be regarded as belonging to the scope of protection determined by the claims submitted for the utility model.

Claims

1. A reaction kettle for preparing oxalic acid, comprising an upper cover (1), a cylinder bottom (2) and a plurality of cylinder bodies (3); a material circulation pipe (4) is arranged between the upper cover (1) and the cylinder bottom (2); a heat exchanger is arranged in the middle of the material circulation pipe (4); and an air outlet pipe (5) is arranged at the top of the upper cover (1); Features: The outer wall of the cylinder (3) is fixedly connected with a connecting pipe (6), and the two ends of the connecting pipe (6) extend to the inner and outer ends of the cylinder (3) respectively. The end of the connecting pipe (6) located on the inner side of the cylinder (3) is provided with an air supply mechanism (7), and the air supply mechanism (7) is used to adapt to the height of the liquid level in the cylinder (3) and control the air flow to blow toward the inner wall of the cylinder (3). The end of the connecting pipe (6) located on the outer side of the cylinder (3) is provided with a gas distribution mechanism (8) that can adapt to the height of the reaction kettle.

2. A reaction kettle for preparing oxalic acid according to claim 1, characterized in that: The air supply mechanism (7) comprises a movable floating tube (9), the movable floating tube (9) is vertically movably connected to the lower end of the connecting tube (6), a compartment (10) is provided on the lower side of the inner wall of the connecting tube (6), a one-way valve A (11) is provided inside the connecting tube (6) on the upper side of the compartment (10), one end of the movable floating tube (9) extending into the compartment (10) is fixedly connected to a vertical tube (12), and the top of the vertical tube (12) is fixedly connected to a convex ring (13) whose size matches that of one end of the one-way valve A (11).

3. A reaction kettle for preparing oxalic acid according to claim 2, characterized in that: A one-way valve B (14) is provided inside the movable floating tube (9) near the lower side, and a downward folding angle is provided near the air flow outlet of the movable floating tube (9).

4. The reactor for preparing oxalic acid according to claim 1, characterized in that: The gas distribution mechanism (8) comprises a connecting pipe (15), one end of which is threadedly connected to an end of the connecting pipe (6) located outside the cylinder (3), and the other end of which is rotatably connected to the outer wall of an upper box (16), a middle box (17) or a bottom box (18), and the total number of the upper boxes (16), the middle boxes (17) and the bottom boxes (18) is adapted to the number of the cylinders (3).

5. A reaction kettle for preparing oxalic acid according to claim 4, characterized in that: The height of the middle box (17) is matched with the height of the cylinder (3); the upper surface and the lower surface of the middle box (17) are respectively provided with plug blocks and slots of sizes matched; the lower surface of the upper box (16) and the upper surface of the bottom box (18) are provided with slots and plug blocks of sizes matched with the size of the middle box (17).

6. A reaction kettle for preparing oxalic acid according to claim 4, characterized in that: A protrusion is provided outwardly at the bottom of the inner wall of the bottom box (18) away from the cylinder (3), and an air inlet pipe (19) with an air outlet direction vertically upward is fixedly installed below the protrusion on the lower surface of the bottom box (18).

7. The reaction kettle for preparing oxalic acid according to claim 1, characterized in that: A boss (20) is provided on the lower surface of the upper cover (1) and the lower surface of the cylinder (3) near the bottom edge of the inner wall, and a groove of matching size is provided on the upper surface of the cylinder (3) and the cylinder bottom (2) at the position corresponding to the boss (20).

8. The reaction kettle for preparing oxalic acid according to claim 1, characterized in that: The outer wall of the cylinder (3) is fixedly connected with a convex ring near the top and the bottom, and the surface of the convex ring is provided with a plurality of vertical and evenly distributed screw holes.

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