A thickening device for crude adipic acid

Abstract

The crude adipic acid thickening device provided in this embodiment of the invention features a central tube and a first porous tube that can move relative to each other. When blowing away the solid portion of the crude adipic acid slurry adhering to the outer filter screen, the central tube and the first porous tube are initially in a closed position. In this state, high-pressure gas cannot escape and remains inside the central tube, causing the pressure inside the central tube to continuously increase until a preset value is reached. Then, the central tube and the first porous tube move from the closed position to the open position. At this time, high-pressure gas is simultaneously and instantaneously released from various points on the first porous tube, blowing away the solid portion of crude adipic acid adhering to the outer filter screen. Compared to direct backflushing of high-pressure gas without accumulation, this embodiment of the invention achieves higher gas pressure inside the central tube. Furthermore, because multiple filter holes on the first porous tube open simultaneously, the pressure of the emitted gas is more uniform, resulting in a better blowing effect.

Description

Technical Field

[0001] This invention relates to the field of candle filter technology, and in particular to a thickening device for crude adipic acid. Background Technology

[0002] Adipic acid, also known as hexanedicarboxylic acid or acetic acid, is a key aliphatic dicarboxylic acid. Its chemical name is Adipic acid or Hexanedioic acid, abbreviated as AA. Adipic acid has the ability to undergo condensation reactions with polyfunctional compounds; therefore, industrially, its condensation reaction with hexamethylenediamine is widely used to produce nylon 66 salt, which, after further polycondensation, yields nylon 66 resin. In addition, adipic acid can react with alcohols to form adipate esters, which play an important role in the manufacture of plasticizers, synthetic lubricants, and polyester polyols. Simultaneously, adipic acid is also used as an acidulant in food and beverages, and as a raw material in various products such as pharmaceuticals, yeast purification, pesticides, adhesives, synthetic leather, synthetic fuels, and fragrances. With the continuous development of my country's petrochemical industry, the demand for adipic acid will continue to grow.

[0003] In the production of adipic acid, copper and vanadium are used as catalysts, and cyclohexanol is oxidized by nitric acid to produce adipic acid. Crude adipic acid is then obtained through crystallization, concentration, and centrifugation. To obtain adipic acid of higher purity, the crude product requires further treatment including dissolution, activated carbon decolorization, recrystallization, concentration, centrifugation, and drying.

[0004] The thickening technology for crude adipic acid is carried out during the production stage of crude adipic acid. The crude adipic acid nitric acid solution obtained from the oxidation process first enters a crystallizer, which consists of multiple crystallization chambers, each with a gradually decreasing operating temperature and pressure in a stepped manner. This design is based on the crystallization curve of the material, allowing adipic acid to crystallize from the nitric acid solution through adiabatic evaporation cooling under vacuum. Next, the slurry containing the adipic acid crystals is fed into a thickening filter and a centrifuge. After centrifugation and dehydration, crude adipic acid is obtained.

[0005] Crude adipic acid thickeners play a crucial role in the production process of adipic acid, and their thickening effect affects the separation efficiency of subsequent centrifugation devices and the production efficiency of adipic acid. Traditionally, crude adipic acid is thickened mainly through candle filters, but existing crude adipic acid thickeners have the disadvantage of insufficient pressure, which leads to insufficient cleaning of the filter screen.

[0006] The information disclosed in the background section of this application is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The applicant discovered during actual production that, based on the thickening of crude adipic acid using a candle filter, after the crude adipic acid slurry adheres to the filter screen to form a filter cake, the filter cake is blown off the filter screen by backflushing with process gas. However, because the backflushing gas usually enters from one end of the filter screen, the gas pressure is higher near the gas inlet and lower further away. The crude adipic acid slurry typically accumulates on the filter screen further away from the gas inlet. After the filter cake near the gas inlet is blown off, since the filter screen is no longer clogged, the backflushing gas exits directly from where the filter cake fell, without backflushing the remaining adhered filter cake, resulting in incomplete backflushing of the filter cake on the filter screen.

[0008] Therefore, it is necessary to provide a thickening device for crude adipic acid to address the problem of insufficient filter cleaning in current crude adipic acid thickeners.

[0009] The above objectives are achieved through the following technical solutions:

[0010] A thickening device for crude adipic acid, comprising:

[0011] The main housing has an interior containing a storage area for accommodating materials.

[0012] A filter assembly is disposed within the receiving area. The filter assembly includes an outer filter screen, a first porous tube, a second porous tube, and a central tube. The outer filter screen has a first axis. The first porous tube and the central tube are disposed along the first axis. The top of the central tube is connected to an external pipeline. A one-way valve is disposed at the bottom of the central tube to restrict material from flowing out from the bottom of the central tube. The central tube wall is provided with multiple filter holes. The central tube is disposed inside the first porous tube, and the two can slide relative to each other along the first axis. Before and after relative sliding, they have corresponding open and closed positions. When in the open position, the filter holes on the first porous tube and the central tube are connected. When in the closed position, the filter holes on the first porous tube and the central tube are misaligned and closed. Multiple second porous tubes are disposed around the first axis. After the pressure inside the central tube reaches a preset value, the first porous tube and the central tube move from the closed position to the open position.

[0013] In one embodiment, the filter assembly further includes a drive motor and a pressure sensor. The pressure sensor is used to detect the pressure inside the central tube. After the pressure inside the central tube reaches a preset value, the drive motor drives the first porous tube and the central tube to move from the closed position to the open position.

[0014] In one embodiment, the filter assembly has an isolation chamber at its bottom, and the drive motor is disposed within the isolation chamber.

[0015] In one embodiment, the filter assembly further includes an upper filter housing and a lower filter housing, the upper filter housing being disposed at the top of the filter assembly and fixedly connected to the main housing, and the lower filter housing being disposed at the bottom of the filter assembly.

[0016] In one embodiment, a guide groove and a guide protrusion are respectively provided on the outer peripheral wall of the central tube and the inner peripheral wall of the first porous tube. The guide protrusion is engaged in the guide groove. When the guide protrusion slides along the guide groove, the central tube and the first porous tube switch between the open position and the closed position.

[0017] In one embodiment, the central tube and the first porous tube are capable of rotating relative to each other about the first axis.

[0018] In one embodiment, the top of the central tube is connected to the negative pressure generator and the booster via an external pipeline.

[0019] In one embodiment, the number of filtering components is multiple.

[0020] In one embodiment, the central tubes in the plurality of filter components move synchronously.

[0021] In one embodiment, the main housing has a second axis, one of the filter components is disposed along the second axis, and the remaining filter components are disposed around the second axis.

[0022] The beneficial effects of this invention are:

[0023] The crude adipic acid thickening device provided in this embodiment of the invention features a central tube and a first porous tube that can move relative to each other. When blowing away the solid portion of the crude adipic acid slurry adhering to the outer filter screen, the central tube and the first porous tube are initially in a closed position. In this state, high-pressure gas cannot escape and remains inside the central tube, causing the pressure inside the central tube to continuously increase until a preset value is reached. Then, the central tube and the first porous tube move from the closed position to the open position. At this time, high-pressure gas is simultaneously and instantaneously released from various points on the first porous tube, blowing away the solid portion of crude adipic acid adhering to the outer filter screen. Compared to direct backflushing of high-pressure gas without accumulation, this embodiment of the invention achieves higher gas pressure inside the central tube. Furthermore, because multiple filter holes on the first porous tube open simultaneously, the pressure of the emitted gas is more uniform, resulting in a better blowing effect. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the structure of a thickening device for crude adipic acid provided in an embodiment of the present invention;

[0025] Figure 2 for Figure 1 Cross-sectional view of a thickening device for crude adipic acid;

[0026] Figure 3 for Figure 1 A partially enlarged view of the thickening device for crude adipic acid;

[0027] Figure 4 This is a cross-sectional view of the first porous tube in a thickening device for crude adipic acid provided in an embodiment of the present invention.

[0028] Figure 5 for Figure 4 A magnified view of a portion of the first porous tube.

[0029] in:

[0030] 100. Main housing; 101. Support leg; 102. Discharge port; 103. Inlet port; 104. Main pipe; 105. Branch pipe; 200. Filter assembly; 210. Outer filter screen; 212. Upper filter screen housing; 214. Lower filter screen housing; 221. First porous pipe; 222. Second porous pipe; 230. Central pipe; 232. One-way valve; 240. Drive motor; 242. Isolation chamber; 250. Guide groove; 251. First section; 252. Second section; 253. Third section; 254. Fourth section; 260. Elastic element. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0032] The serial numbers assigned to components in this document, such as "first," "second," etc., are merely used to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0033] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0034] This invention provides a thickening device for crude adipic acid, which is mainly used in the production stage of crude adipic acid for thickening process. Of course, it can also be applied to the thickening process of similar or related compounds in the production stage.

[0035] Specifically, such as Figures 1-5 As shown, the thickening device for crude adipic acid provided in this embodiment of the invention includes a main housing 100 and a filter assembly 200.

[0036] The main shell 100 serves as the main body of the thickening device for crude adipic acid. On one hand, it forms a relatively closed working environment so that the material can be processed within this environment. In this embodiment, the main shell 100 has a receiving area inside for containing the material. The receiving area is relatively isolated from the external environment, and the thickening process of crude adipic acid can be completed within the receiving area. The receiving area can also exchange materials with the external environment through specific pipelines when needed, thereby completing the feeding, discharging and other steps required for the thickening process of crude adipic acid.

[0037] On the other hand, the main housing 100 serves as the mounting base for other components. In this embodiment, multiple support legs 101 are provided at the bottom of the main housing 100, allowing the thickening device for crude adipic acid to be placed on the ground or other stable surfaces. A discharge port 102 is provided at the bottom of the main housing 100 for discharging materials during cleaning or other steps. A feed inlet 103 is provided on the bottom side of the main housing 100 for feeding materials into the receiving area. A main pipe 104 and multiple branch pipes are provided on the top side of the main housing 100. 105, one end of branch pipe 105 is connected to the containment area, and the other end is connected to the main pipe 104. Each branch pipe 105 is equipped with an independently controllable valve. The main pipe 104 is connected to the high-pressure generator and the negative pressure generator. When the high-pressure generator is working, high-pressure gas can be introduced into the containment area through the main pipe 104 and branch pipe 105. When the negative pressure generator is working, the material in the containment area can be sucked out through the branch pipe 105 and the main pipe 104. The top of the main shell 100 is also equipped with auxiliary accessories such as a reverse pressure port, a spray water inlet and a pressure gauge.

[0038] The filter assembly 200 is set in the containment area. After the crude adipic acid slurry enters the containment area, the slurry undergoes solid-liquid separation and thickening through the filter assembly 200. The clear liquid is drawn out from inside the filter assembly 200 and from the branch pipe 105 and the main pipe 104, and enters the mother liquor tank through the gas-liquid separation device. The filtered crude adipic acid slurry adheres to the surface of the filter assembly 200, peels off from the surface of the filter assembly 200 and falls into the bottom of the containment area, and is discharged from the bottom discharge port 102. The discharged filtered crude adipic acid slurry can enter the centrifuge for further centrifugation, dehydration and thickening.

[0039] The filter assembly 200 includes an outer filter screen 210, a first porous tube 221, a second porous tube 222, and a central tube 230. Normally, the outer filter screen 210 is cylindrical in shape and has a first axis. The outer filter screen 210 is located on the outermost side of the entire filter assembly 200. The clear liquid in the crude adipic acid crystal slurry can be filtered through the outer filter screen 210 and enter the interior of the filter assembly 200. The solid part in the crude adipic acid crystal slurry cannot pass through the outer filter screen 210 and adheres to the outer filter screen 210. The first porous tube 221 and the central tube 230 are arranged along the first axis. The top of the central tube 230 is connected to an external pipeline. In this embodiment, the central tube 230 is connected to the branch pipe 105. A one-way valve 232 is provided at the bottom of the central tube 230. The one-way valve 232 restricts the material from flowing out from the bottom of the central tube 230. Multiple filter holes are provided on the wall of the central tube 230. The central tube 230 is located inside the first porous tube 221 and the two can slide relative to each other along the first axis. They have corresponding open and closed positions before and after relative sliding. When in the open position, the filter holes on the first porous tube 221 and the central tube 230 are connected. When in the closed position, the filter holes on the first porous tube 221 and the central tube 230 are misaligned and closed. Multiple second porous tubes 222 are arranged around the first axis.

[0040] When thickening crude adipic acid, the crude adipic acid slurry enters from the feed inlet 103 and fills or almost fills the entire containment area. At this time, the central tube 230 and the first porous tube 221 are in the conductive position, the negative pressure generator is working, and the high pressure generator is not working. The clear liquid in the crude adipic acid slurry can be filtered through the outer filter screen 210 and enter the filter assembly 200. It flows through the second porous tube 222, the first porous tube 221, the central tube 230, the branch tube 105 and the main tube 104 in sequence. Under the action of the negative pressure generator, the clear liquid is extracted. The solid portion of the crude adipic acid slurry cannot pass through the outer filter screen 210 and adheres to it. After a certain time or amount of adhesion, the central tube 230 and the first porous tube 221 move to the closed position, the negative pressure generator stops working, and the high pressure generator starts working. The high pressure generator introduces high pressure gas into the central tube 230. At this time, since the central tube 230 and the first porous tube 221 are in the closed position, the high pressure gas inside the central tube 230 cannot be discharged, and the pressure inside the central tube 230 gradually increases. When the pressure in the central tube 230 increases to a certain preset value, the central tube 230 and the first porous tube 221 move from the closed position to the open position. At this time, the high pressure gas is released simultaneously and instantaneously from various parts of the first porous tube 221, blowing away the crude adipic acid solid portion adhering to the outer filter screen 210.

[0041] Therefore, the thickening device for crude adipic acid provided in this embodiment of the invention, by setting a relatively movable central tube 230 and a first porous tube 221, when blowing away the solid portion of crude adipic acid crystal slurry adhering to the outer filter screen 210, the central tube 230 and the first porous tube 221 are initially in a closed position. In this state, high-pressure gas cannot be discharged and remains in the central tube 230, causing the pressure inside the central tube 230 to continuously increase. After reaching a preset value, the central tube 230 and the first porous tube 221 move from the closed position to the open position. At this time, high-pressure gas is simultaneously and instantaneously released from various points on the first porous tube 221, blowing away the solid portion of crude adipic acid adhering to the outer filter screen 210. Compared with direct backflushing of high-pressure gas without accumulation, on the one hand, the gas pressure in the central tube 230 in this embodiment of the invention is higher; on the other hand, since multiple filter holes on the first porous tube 221 are opened simultaneously, the pressure of the discharged gas is more uniform, resulting in a better blowing effect.

[0042] In one embodiment of the present invention, the filter assembly 200 further includes a drive motor 240 and a pressure sensor. The pressure sensor is used to detect the pressure inside the central tube 230. After the pressure inside the central tube 230 reaches a preset value, the drive motor 240 drives the first porous tube 221 and the central tube 230 to move from the closed position to the open position. In this embodiment, the filter assembly 200 also includes an upper filter housing 212 and a lower filter housing 214. One of the upper filter housing 212 and the lower filter housing 214 is directly or indirectly fixedly connected to the main housing 100, and the other is fixedly connected to the one of the upper filter housing 212 and the lower filter housing 214 that is fixedly connected to the main housing 100 through the first porous tube 221 or the second porous tube 222. The drive motor 240 is disposed on the lower filter housing 214, and the output shaft of the drive motor 240 is directly or indirectly connected to the central tube 230 and drives the central tube 230 to move.

[0043] In one embodiment of the present invention, the filter assembly 200 is provided with an isolation chamber 242 at its bottom, and the drive motor 240 is disposed in the isolation chamber 242.

[0044] In one embodiment of the present invention, a guide groove 250 and a guide protrusion (not shown in the figure) are respectively provided on the outer peripheral wall of the central tube 230 and the inner peripheral wall of the first porous tube 221. The guide protrusion is engaged in the guide groove 250. When the guide protrusion slides along the guide groove 250, the central tube 230 and the first porous tube 221 switch between the open position and the closed position. An elastic member 260 is provided between the central tube 230 and the first porous tube 221. The elastic force of the elastic member 260 always causes the central tube 230 to move upward. In this embodiment, the guide groove 250 is a vertically arranged straight groove. In the initial state, the guide protrusion is located at the top of the guide groove 250, and the central tube 230 and the first porous tube 221 are in a closed position. When high-pressure gas is introduced, the pressure inside the central tube 230 continuously increases and squeezes the elastic element 260, causing the central tube 230 to move downward. When the pressure reaches a preset value, the elastic element 260 is compressed by a preset distance. At this time, the central tube 230 and the first porous tube 221 move to the open position, and the high-pressure gas is released instantly, blowing away the coarse adipic acid solid part adhering to the outer filter screen 210. The central tube 230 returns to the initial position under the action of the elastic element 260.

[0045] In one embodiment of the present invention, the central tube 230 and the first porous tube 221 are rotatable relative to each other around a first axis. The guide groove 250 includes a first segment 251, a second segment 252, a third segment 253, and a fourth segment 254 connected sequentially. The first segment 251 is inclined downwards, the second segment 252 is vertical, the third segment 253 is inclined downwards in the opposite direction to the first segment 251, and the fourth segment 254 is vertical. Initially, the guide protrusion is located at the connection between the first segment 251 and the fourth segment 254, and the central tube 230 and the first porous tube 221 are in a closed position. When high-pressure gas is introduced, due to the inclination of the first segment 251, there is friction between the guide protrusion and the guide groove 250. When the pressure inside the central tube 230 reaches a preset value, the guide protrusion overcomes the friction and moves along the first segment 251 to the intersection of the first segment 251 and the second segment 252. Then, because the second segment 252 is vertical, the friction between the guide protrusion and the guide groove 250 decreases instantaneously. The central tube 230 moves rapidly downwards to the intersection of the second section 252 and the third section 253, and the central tube 230 and the first porous tube 221 move to the conducting position. The high-pressure gas is released instantly, blowing away the coarse adipic acid solids adhering to the outer filter screen 210. Due to the large inclination of the third section 253, the central tube 230 drives the guide protrusion to slide along the third section 253 to the intersection of the third section 253 and the fourth section 254 under its own weight. Finally, the guide protrusion is restored to its initial position by manual or other reset methods.

[0046] In one embodiment of the present invention, the number of filter components 200 is multiple.

[0047] In one embodiment of the present invention, the central tube 230 of the plurality of filter components 200 moves synchronously.

[0048] In one embodiment of the present invention, the main housing 100 has a second axis, one filter assembly 200 is disposed along the second axis, and the other filter assemblies 200 are disposed around the second axis.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A thickening device for crude adipic acid, characterized in that, include: The main housing has an interior containing a storage area for accommodating materials. A filter assembly is disposed within the receiving area. The filter assembly includes an outer filter screen, a first porous tube, a second porous tube, and a central tube. The outer filter screen has a first axis. The first porous tube and the central tube are disposed along the first axis. The top of the central tube is connected to an external pipeline. A one-way valve is disposed at the bottom of the central tube to restrict material from flowing out from the bottom of the central tube. Multiple filter holes are disposed on the wall of the central tube. The central tube is disposed inside the first porous tube, and the two can slide relative to each other along the first axis. They have corresponding open and closed positions before and after relative sliding. When in the open position, the filter holes on the first porous tube and the central tube are connected. When in the closed position, the filter holes on the first porous tube and the central tube are misaligned and closed. Multiple second porous tubes are arranged around the first axis; after the pressure inside the central tube reaches a preset value, the first porous tube and the central tube move from the closed position to the open position.

2. The thickening device for crude adipic acid according to claim 1, characterized in that, The filter assembly also includes a drive motor and a pressure sensor. The pressure sensor is used to detect the pressure inside the central tube. After the pressure inside the central tube reaches a preset value, the drive motor drives the first porous tube and the central tube to move from the closed position to the open position.

3. The thickening device for crude adipic acid according to claim 2, characterized in that, The filter assembly has an isolation chamber at its bottom, and the drive motor is located inside the isolation chamber.

4. The thickening device for crude adipic acid according to claim 1, characterized in that, The filter assembly further includes an upper filter housing and a lower filter housing. The upper filter housing is disposed at the top of the filter assembly and is fixedly connected to the main housing. The lower filter housing is disposed at the bottom of the filter assembly.

5. The thickening device for crude adipic acid according to claim 1, characterized in that, The outer peripheral wall of the central tube and the inner peripheral wall of the first porous tube are respectively provided with a guide groove and a guide protrusion. The guide protrusion is engaged in the guide groove. When the guide protrusion slides along the guide groove, the central tube and the first porous tube switch between the open position and the closed position. An elastic element is provided between the central tube and the first porous tube. The elastic force of the elastic element always causes the central tube to move upward.

6. The thickening device for crude adipic acid according to claim 5, characterized in that, The central tube and the first porous tube are capable of rotating relative to each other around the first axis.

7. The thickening device for crude adipic acid according to claim 1, characterized in that, The top of the central tube is connected to the negative pressure generator and the booster via an external pipeline.

8. The thickening apparatus for crude adipic acid according to any one of claims 1-7, characterized in that, The number of filter components is multiple.

9. The thickening device for crude adipic acid according to claim 8, characterized in that, The central tubes in the multiple filter components move synchronously.

10. The thickening device for crude adipic acid according to claim 8, characterized in that, The main housing has a second axis, one of the filter components is disposed along the second axis, and the remaining filter components are disposed around the second axis.

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