Device for producing benzoic acid by double-falling-film fractional crystallization method

Abstract

A device for producing benzoic acid through a double-falling-film fractional crystallization method comprises a double-falling-film crystallizer body, a heat exchange pipe and a cooling pipe, a feeding pipe is arranged at the upper end of the double-falling-film crystallizer body and communicated with a material distributing pipe, each discharging port formed in the material distributing pipe is connected with the heat exchange pipe, and the cooling pipe is communicated with the heat exchange pipe. The double-falling-film crystallizer is characterized in that a plurality of groups of distributors are arranged between the inner wall of the cooling pipe and the outer wall of the heat exchange pipe, a cooling medium liquid inlet formed in one side of the upper end of the double-falling-film crystallizer main body is connected with a liquid outlet of a cooling medium box through a circulating pump, and the liquid outlet of the cooling medium box is connected with a liquid outlet of the cooling medium box. According to the double-falling-film crystallizer, the cooling medium is conveyed into the double-falling-film crystallizer body from a high position to a low position, the consumed energy is reduced, the flowing process of the heat exchange medium is accelerated, and therefore the machining time is saved.

Description

Technical Field

[0001] This utility model relates to the technical field of equipment for producing benzaldehyde by double falling film fractional crystallization, and particularly to an apparatus for producing benzoic acid by double falling film fractional crystallization. Background Technology

[0002] The current benzoic acid production process uses a fractional crystallization process to produce high-quality benzoic acid. By utilizing fractional crystallization technology and the difference in freezing points between benzoic acid and biphenyls, orthophthalamides and other organic impurities, the above impurities in the industrial-grade benzoic acid obtained in the benzoic acid purification process are separated out, resulting in a high-quality, high-purity lean benzoic acid product.

[0003] Currently, a double falling film staged crystallizer is commonly used to produce benzoic acid. The principle is that the liquid enters the heat exchange tubes of the crystallizer and flows downwards in a film-like manner within the inner wall of the tubes. At the same time, a heat exchange medium is introduced into the crystallizer, causing it to flow upwards along the outer wall of the heat exchange tubes. Through heat exchange with the heat exchange medium, the temperature inside the heat exchange tubes gradually decreases, resulting in crystallization as the liquid flows downwards. The generated crystals are then recovered. However, since the heat exchange medium is introduced into the crystallizer from a lower temperature to a higher temperature, it needs to be filled completely and flow upwards. This cyclic heat exchange process consumes a significant amount of energy and prolongs the processing time.

[0004] Therefore, to solve the above problems, a double falling film fractional crystallization method for producing benzoic acid is designed. Utility Model Content

[0005] In view of the above-mentioned technical problems, this utility model provides a device for producing benzoic acid by double falling film graded crystallization. The device is designed to deliver the cooling medium into the main body of the double falling film crystallizer in a high-low direction, and the medium flows from top to bottom on the outer wall of the heat exchange tube. Compared with the current method of the heat exchange medium flowing from bottom to top in a full state, the energy consumption is reduced and the flow process of the heat exchange medium is accelerated, thereby saving processing time.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows:

[0007] A benzoic acid production apparatus using a double falling film staged crystallization method includes a double falling film crystallizer body, heat exchange tubes, and cooling tubes. The double falling film crystallizer body has a feed pipe at its upper end, which is connected to a distribution pipe. Each outlet on the distribution pipe is connected to a heat exchange tube, which is located at the center of the cooling tube. The apparatus is characterized by having multiple sets of distributors installed between the inner wall of the cooling tube and the outer wall of the heat exchange tube. A cooling medium inlet located on one side of the upper end of the double falling film crystallizer body is connected to the outlet of a cooling medium tank via a circulating pump. The return outlet of the cooling medium tank is connected to a cooling medium outlet located on one side of the lower end of the double falling film crystallizer body via a pipe.

[0008] The distributor is a distribution plate, and the distribution plate is provided with multiple liquid outlet holes.

[0009] Specifically, the upper end of the heat exchange tube is installed inside the body of the double falling film crystallizer via an upper fixing plate.

[0010] Specifically, the lower end of the heat exchange tube is installed inside the body of the double falling film crystallizer via a lower fixing plate.

[0011] Specifically, a guide plate is provided at the upper end of the cooling pipe, and a guide hole is provided on the guide plate.

[0012] Specifically, the lower end of the cooling pipe is installed inside the body of the double falling film crystallizer via a fixing plate.

[0013] Specifically, a discharge pipe is provided at the bottom of the main body of the double falling film crystallizer.

[0014] Specifically, the cooling medium tank is connected to an external heat exchange assembly to cool and reduce the temperature of the medium inside the cooling medium tank.

[0015] The beneficial effects of this utility model are:

[0016] This invention designs a high-inlet, low-outlet cooling medium delivery system into the main body of the double falling film crystallizer. The medium flows downwards on the outer wall of the heat exchange tube. Compared to the current bottom-up flow, the downward flow of the heat exchange medium reduces energy consumption and speeds up the flow process, thereby saving processing time.

[0017] This invention arranges multiple sets of distributors sequentially between the outer wall of the heat exchange tube and the inner wall of the cooling tube, so that the heat exchange medium is evenly distributed when flowing between the outer wall of the heat exchange tube and the inner wall of the cooling tube, and better forms a film flow on the outer wall of the heat exchange tube, thereby enhancing the heat exchange effect and increasing the crystallization rate of benzoic acid production. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the apparatus for producing benzoic acid using the double falling film fractional crystallization method of this utility model;

[0019] Figure 2 This is a schematic cross-sectional view of the structure at point A in the apparatus for producing benzoic acid using the double falling film fractional crystallization method of this utility model.

[0020] Figure 3 This is a partial structural diagram of the upper part of the apparatus for producing benzoic acid using the double falling film fractional crystallization method of this utility model;

[0021] Figure 4 This is a partial structural diagram of the lower end of the apparatus for producing benzoic acid using the double falling film fractional crystallization method of this utility model;

[0022] Figure 5 This is a schematic diagram of the flow guide plate of the apparatus for producing benzoic acid using the double falling film fractional crystallization method of this utility model; as shown in the figure: 1. Main body of the double falling film crystallizer, 11. Feed pipe, 12. Discharge pipe, 13. Cooling medium inlet, 14. Cooling medium outlet, 2. Distribution pipe, 3. Heat exchange pipe, 4. Cooling pipe, 5. Cooling medium tank, 6. Circulation pump, 7. Distributor, 71. Distribution plate, 72. Discharge hole, 81. Upper fixed plate, 82. Lower fixed plate, 9. Flow guide plate, 91. Flow guide hole, 10. Fixed plate. Detailed Implementation

[0023] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0024] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and 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, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0026] Example 1

[0027] As shown in the figure, the upper end of the double falling film crystallizer body 1 is provided with a feed pipe 11, and the lower end is provided with a discharge pipe 12. The feed pipe 11 is connected to the distribution pipe 2 inside the crystallizer body. Each discharge port on the distribution pipe 2 is connected to a heat exchange tube 3. The upper end of the heat exchange tube 3 is installed inside the double falling film crystallizer body 1 through an upper fixing plate 81, and the lower end of the heat exchange tube 3 is installed inside the double falling film crystallizer body 1 through a lower fixing plate 81. The heat exchange tube 3 extends into the cooling pipe 4. The cooling pipe 4 is located at its center. Multiple distributors 7 are arranged sequentially from top to bottom between the inner wall of the cooling pipe 4 and the outer wall of the heat exchange pipe 3. Each distributor 7 is a distribution plate 71 with multiple liquid outlet holes 72. A guide plate 9 is located at the upper end of the cooling pipe 4, and multiple guide holes 91 are provided on the guide plate 9, each communicating with the upper end of the cooling pipe 4. The lower end of the cooling pipe 4 is installed inside the double falling film crystallizer body 1 via a fixing plate 10.

[0028] The cooling medium inlet 13, located on one side of the upper end of the double falling film crystallizer body 1, is connected to the outlet of the cooling medium tank 5 via a circulating pump 6. The return port of the cooling medium tank 5 is connected to the cooling medium drain port 14, located on one side of the lower end of the double falling film crystallizer body 1, via a pipe.

[0029] It should be noted that the cooling medium tank 5 is connected to an external heat exchange device, and the medium in the cooling medium tank 5 is cooled down by the heat exchange device. The use of a heat exchange device to cool the cooling medium is an existing technology, so it will not be described in detail in this application.

[0030] Example 2

[0031] In this invention, the liquid material enters the distribution pipe 2 through the feed pipe 11 and is then distributed into each heat exchange tube 3. The material flows from top to bottom in a film-like manner on the inner wall of the heat exchange tube 3. At this time, cooling medium is introduced into the main body 1 of the double falling film crystallizer. The cooling medium is introduced from the liquid inlet 11 at the upper end of the main body 1 of the double falling film crystallizer through the circulation pump 6 and flows into the cooling tube 4 through the guide holes 91 on the guide plate 9. The material flows from bottom to top on the outer wall of the heat exchange tube 3. Through heat exchange with the cooling medium, the temperature inside the heat exchange tube 3 gradually decreases. The material flows from top to bottom while producing benzoic acid crystals. The generated crystals are recovered from the discharge port 12 at the bottom. The cooling medium is heat transfer oil.

[0032] This invention designs a high-inlet, low-outlet cooling medium delivery system into the main body of the double falling film crystallizer. The medium flows from top to bottom on the outer wall of the heat exchange tube 3. Compared to the current bottom-up flow system, this process reduces energy consumption and speeds up the flow of the cooling medium, thus saving processing time.

[0033] This invention arranges multiple sets of distributors 7 sequentially between the outer wall of the heat exchange tube 3 and the inner wall of the cooling tube 4, so that the heat exchange medium is evenly distributed when flowing between the outer wall of the heat exchange tube and the inner wall of the cooling tube, and better forms a film flow on the outer wall of the heat exchange tube 3, thereby enhancing the heat exchange effect and increasing the crystallization rate of benzoic acid production.

[0034] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. The various components mentioned in this utility model are common technologies in the existing field. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A device for producing benzoic acid using a double falling film staged crystallization method, comprising a double falling film crystallizer body, heat exchange tubes, and cooling tubes, wherein a feed pipe is provided at the upper end of the double falling film crystallizer body, the feed pipe is connected to a distribution pipe, each outlet on the distribution pipe is connected to a heat exchange tube, and the heat exchange tube is located at the center of the cooling tube, characterized in that... Multiple distributors are installed between the inner wall of the cooling pipe and the outer wall of the heat exchange pipe. The cooling medium inlet on one side of the upper end of the double falling film crystallizer body is connected to the outlet of the cooling medium tank through a circulating pump. The return port of the cooling medium tank is connected to the cooling medium drain port on one side of the lower end of the double falling film crystallizer body through a pipe.

2. The apparatus for producing benzoic acid using the double falling film fractional crystallization method according to claim 1, characterized in that... The distributor is a distribution plate, and the distribution plate is provided with multiple liquid outlet holes.

3. The apparatus for producing benzoic acid using the double falling film fractional crystallization method according to claim 1, characterized in that... The upper end of the heat exchange tube is installed inside the body of the double falling film crystallizer via an upper fixing plate.

4. The apparatus for producing benzoic acid using the double falling film fractional crystallization method according to claim 1, characterized in that... The lower end of the heat exchange tube is installed inside the body of the double falling film crystallizer via a lower fixing plate.

5. The apparatus for producing benzoic acid using the double falling film fractional crystallization method according to claim 1, characterized in that... The upper end of the cooling pipe is provided with a guide plate, and the guide plate is provided with guide holes.

6. The apparatus for producing benzoic acid using the double falling film fractional crystallization method according to claim 1, characterized in that... The lower end of the cooling pipe is installed inside the body of the double falling film crystallizer via a fixing plate.

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