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

Abstract

The device comprises a double-falling-film crystallizer main body, a heat exchange pipe and a cooling pipe, a feeding pipe is arranged at the upper end of the double-falling-film crystallizer main body, the feeding pipe is 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 main body from a high position to a low position, the consumed energy is reduced, the flowing process of a heat exchange medium is accelerated, and therefore the machining time is saved.

Description

Technical Field

[0001] The invention relates to the technical field of equipment for producing benzaldehyde by double falling film fractional crystallization, and in particular to a device and method for producing benzoic acid by double falling film fractional crystallization. Background Art

[0002] The current production process of benzoic acid adopts the fractional crystallization process to produce high-quality benzoic acid. By utilizing the fractional crystallization technology and the different freezing points of benzoic acid, biphenyls, ortho-phthalates and other organic impurities, the above impurities in the industrial-grade benzoic acid obtained in the benzoic acid purification process are separated out to obtain high-quality, high-purity benzoic acid products.

[0003] At present, double falling film graded crystallizers are usually used to produce benzoic acid. The principle is that the liquid enters the heat exchange tube in the crystallizer and flows from top to bottom in the inner wall of the heat exchange tube in the form of a film. At this time, the heat exchange medium is input into the crystallizer to flow from bottom to top on the outer wall of the heat exchange tube. After heat exchange with the heat exchange medium, the temperature in the heat exchange tube is gradually reduced, and crystallization is carried out while flowing from top to bottom, and the produced crystals are recovered. However, the heat exchange medium is input into the crystallizer at a low input and high output, so it needs to flow from bottom to top in a full state. A large amount of energy is consumed in the cycle heat exchange process, which also prolongs the processing and production time.

[0004] Therefore, in order to solve the above problems, a device and method for producing benzoic acid by double falling film fractional crystallization method are designed to solve the above problems. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a device and method for producing benzoic acid by a double falling film fractional crystallization method. The cooling medium is designed to be transported from a high place to a low place into the main body of the double falling film crystallizer, and flows from top to bottom on the outer wall of the heat exchange tube. Compared with the current bottom-up flow in a full state, the downstream flow process of the heat exchange medium consumes less energy and speeds up the flow process of the heat exchange medium, thereby saving processing time.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] A device for producing benzoic acid by double falling film fractional crystallization method comprises a double falling film crystallizer body, a heat exchange tube and a cooling tube, wherein a feed tube is arranged at the upper end of the double falling film crystallizer body, the feed tube is communicated with a distribution tube, each discharge port arranged on the distribution tube is respectively connected with a heat exchange tube, the heat exchange tube is located at the center position inside the cooling tube, and is characterized in that a plurality of groups of distributors are arranged between the inner wall of the cooling tube and the outer wall of the heat exchange tube, a cooling medium liquid inlet arranged at one side of the upper end of the double falling film crystallizer body is connected with a liquid outlet of a cooling medium box through a circulating pump, and a liquid return port of the cooling medium box is connected with a cooling medium liquid discharge port arranged at one side of the lower end of the double falling film crystallizer body through a pipeline,

[0008] The distributor is a distribution plate, and a plurality of liquid outlet holes are arranged on the distribution plate.

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

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

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

[0012] Specifically, the lower end of the cooling tube is installed in the main body of the double falling film crystallizer through a fixing plate.

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

[0014] Specifically, the cooling medium box is connected to an external heat exchange component to cool the medium in the cooling medium box.

[0015] The method for producing benzoic acid by double falling film fractional crystallization method comprises the following specific steps:

[0016] S1. The material liquid is fed into the distribution pipe inside the main body of the double falling film crystallizer through the feed pipe, and then flows into each heat exchange tube through the distribution pipe. The material flows from top to bottom in the inner wall of the heat exchange tube in the form of a film;

[0017] S2. Start the circulation pump to circulate the cooling medium into the cooling pipe in the double falling film crystallizer body 1, enter the cooling medium from the liquid inlet at the upper end of the double falling film crystallizer body, flow into the cooling pipe through the guide holes on the guide plate, flow from bottom to top on the outer wall of the heat exchange tube, and the heat exchange tube exchanges heat with the cooling medium, so that the temperature in the heat exchange tube is gradually reduced, and the material flows from top to bottom while producing benzoic acid crystals;

[0018] S3. The benzoic acid crystals produced in step S2 are moved to the bottom of the double falling film crystallizer body and discharged from the discharge port at the bottom for recovery.

[0019] Specifically, the cooling medium is heat transfer oil.

[0020] Beneficial effects of the present invention:

[0021] The present invention is designed to transport the cooling medium into the main body of the double falling film crystallizer from high to low, and flows from top to bottom on the outer wall of the heat exchange tube. Compared with the current flow from bottom to top in a full state, the downstream flow process of the heat exchange medium consumes less energy and speeds up the flow process of the heat exchange medium, thereby saving processing time;

[0022] The present invention arranges a plurality of groups of distributors in sequence 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 amount of benzoic acid production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the device and method for producing benzoic acid by double falling film fractional crystallization method of the present invention;

[0024] Figure 2 It is a schematic cross-sectional structure diagram of the structure at A of the device and method for producing benzoic acid by double falling film fractional crystallization method of the present invention;

[0025] Figure 3 It is a schematic diagram of the upper part of the structure of the device and method for producing benzoic acid by double falling film fractional crystallization method of the present invention;

[0026] Figure 4 It is a schematic diagram of the lower part structure of the device and method for producing benzoic acid by double falling film fractional crystallization method of the present invention;

[0027] Figure 5 It is a structural schematic diagram of a guide plate of the device and method for producing benzoic acid by double falling film fractional crystallization method of the present invention;

[0028] As shown in the figure: 1. Double falling film crystallizer body, 11. Feed pipe, 12. Discharge pipe, 13. Cooling medium inlet, 14. Cooling medium discharge port, 2. Distribution pipe, 3. Heat exchange pipe, 4. Cooling pipe, 5. Cooling medium box, 6. Circulation pump, 7. Distributor, 71. Distribution plate, 72. Liquid outlet, 81. Upper fixed plate, 82. Lower fixed plate, 9. Guide plate, 91. Guide hole, 10. Fixed plate. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Example 1

[0033] As shown in the figure, a feed pipe 11 is provided at the upper end of the double falling film crystallizer body 1, and a discharge pipe 12 is provided at the bottom of the lower end. The feed pipe 11 is connected to the distribution pipe 2 inside the crystallizer body. Each discharge port provided on the distribution pipe 2 is connected to the heat exchange pipe 3 respectively. The upper end of the heat exchange pipe 3 is installed in the double falling film crystallizer body 1 through the upper fixing plate 81, and the lower end of the heat exchange pipe 3 is installed in the double falling film crystallizer body 1 through the lower fixing plate 81, and the heat exchange pipe 3 extends into the cooling pipe 4. The cooling tube 4 is provided with a plurality of distributors 7 between the inner wall of the cooling tube 4 and the outer wall of the heat exchange tube 3 from top to bottom. The distributor 7 is a distribution plate 71. A plurality of liquid outlet holes 72 are provided on the distribution plate 71. A guide plate 9 is provided at the upper end of the cooling tube 4. A plurality of guide holes 91 are provided on the guide plate 9. Each guide hole is communicated with the upper end port of the cooling tube 4. The lower end of the cooling tube 4 is installed in the double falling film crystallizer body 1 through a fixing plate 10.

[0034] The cooling medium liquid inlet 13 arranged on the upper side of the double falling film crystallizer body 1 is connected to the liquid outlet of the cooling medium box 5 through the circulating pump 6, and the return liquid port of the cooling medium box 5 is connected to the cooling medium liquid discharge port 14 arranged on the lower side of the double falling film crystallizer body 1 through a pipeline.

[0035] It should be noted that the cooling medium box 5 is connected to an external heat exchange device, and the medium in the cooling medium box 5 is cooled by the heat exchange device. Using the heat exchange device to perform heat exchange and cooling on the cooling medium is an existing technical means, so it will not be described in detail in this application.

[0036] Example 2

[0037] In the present invention, the material liquid enters the distribution pipe 2 through the feed pipe 11, and is divided into each heat exchange tube 3. The material flows from top to bottom in the inner wall of the heat exchange tube 3 in a film-like manner. At this time, a cooling medium is input into the double falling film crystallizer body 1, and is input from the cooling medium liquid inlet 11 at the upper end of the double falling film crystallizer body 1 through the circulation pump 6. It flows into the cooling tube 4 through the guide holes 91 on the guide plate 9, and flows from bottom to top on the outer wall of the heat exchange tube 3. After heat exchange with the cooling medium, the temperature in the heat exchange tube 3 is gradually reduced. The material flows from top to bottom while producing benzoic acid crystals, and the produced crystals are recovered from the discharge port 12 at the bottom, wherein the cooling medium uses heat transfer oil.

[0038] The present invention is designed to transport the cooling medium into the double falling film crystallizer body from high to low, and flows from top to bottom on the outer wall of the heat exchange tube 3. Compared with the current flow from bottom to top in a full state, the downstream flow process of the heat exchange medium consumes less energy and speeds up the flow process of the heat exchange medium, thereby saving processing time;

[0039] The present invention sequentially arranges a plurality of distributors 7 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 amount of benzoic acid production.

[0040] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. The various components mentioned in the present invention are common technologies in the existing field. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A device for producing benzoic acid by double falling film fractional crystallization method, comprising a double falling film crystallizer body, a heat exchange tube and a cooling tube, wherein a feed tube is arranged at the upper end of the double falling film crystallizer body, the feed tube is communicated with a feed distribution tube, each discharge port arranged on the feed distribution tube is connected with a heat exchange tube respectively, the heat exchange tube is located at the center of the cooling tube, and is characterized in that: A plurality of groups of distributors are arranged between the inner wall of the cooling tube and the outer wall of the heat exchange tube. The cooling medium liquid inlet arranged on one side of the upper end of the double falling film crystallizer body is connected to the liquid outlet of the cooling medium box through a circulating pump. The liquid return port of the cooling medium box is connected to the cooling medium liquid discharge port arranged on one side of the lower end of the double falling film crystallizer body through a pipeline.

2. The double falling film fractional crystallization method for producing benzoic acid according to claim 1, characterized in that The distributor is a distribution plate, and a plurality of liquid outlet holes are arranged on the distribution plate.

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

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

5. The double falling film fractional crystallization method for producing benzoic acid according to claim 1, characterized in that A guide plate is arranged at the upper end of the cooling pipe, and a guide hole is arranged on the guide plate.

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

7. A method for producing benzoic acid by double falling film fractional crystallization, the specific steps of which are as follows: S1. The material liquid is fed into the distribution pipe inside the main body of the double falling film crystallizer through the feed pipe, and then flows into each heat exchange tube through the distribution pipe. The material flows from top to bottom in the inner wall of the heat exchange tube in the form of a film; S2. Start the circulation pump to circulate the cooling medium into the cooling pipe in the double falling film crystallizer body 1, enter the cooling medium from the liquid inlet at the upper end of the double falling film crystallizer body, flow into the cooling pipe through the guide holes on the guide plate, flow from bottom to top on the outer wall of the heat exchange tube, and the heat exchange tube exchanges heat with the cooling medium, so that the temperature in the heat exchange tube is gradually reduced, and the material flows from top to bottom while producing benzoic acid crystals; S3. The benzoic acid crystals produced in step S2 are moved to the bottom end of the double falling film crystallizer body and discharged from the discharge port at the bottom for recovery.

8. The method for producing benzoic acid by the double falling film fractional crystallization method according to claim 7, characterized in that The cooling medium is heat transfer oil.

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