Drying device for isocyanate production system

Abstract

The utility model relates to a drying device for an isocyanate production system, which comprises a drying tower body, the drying tower body comprises an impact section and a drying section, the drying section is arranged above the impact section, the bottom of the impact section is provided with a feed nozzle, the top of the drying section is provided with a discharge port, and a gas distributor is arranged in the impact section. The gas distributor is used for spraying impact gas into the impact section, and a drying agent is arranged in the drying section. The drying device provided by the utility model is used for removing water from a solvent which is circularly operated by an isocyanate production system before starting. The gas distributor is arranged to eject impact gas, so that solvent liquid drops collide with one another to form small liquid drops, and the drying agent can fully dry the solvent. After the solvent is dried by the drying device, the water content of the solvent can be less than 10ppm, and the dried solvent enters an isocyanate production system and then is started, so that the side reaction can be obviously reduced, and a high-quality product is obtained.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of isocyanate production, in particular to a drying device for an isocyanate production system. BACKGROUND

[0002] The photochemical reaction is a key process in the preparation of isocyanate. The water in the isocyanate production system, the intermediate carbamoyl chloride and the -NCO group in the product react to generate by-products urea, thereby reducing the product quality. During the shutdown and maintenance, water is easily introduced during the disassembly and reassembly of the equipment, and the isocyanate production system needs to be dehydrated before starting.

[0003] CN110003054B discloses the use of a solvent in the dehydration system, the water is enriched and separated by the light gas column and the solvent refining column top gas-liquid separation tank, and is discharged through the drainage pipe. Although this method can remove a large amount of water in the system, a lot of water will still remain, and the water content in the solvent chlorobenzene will increase after operation and still needs secondary drying treatment before use.

[0004] In addition, no technical document has disclosed a method for removing water in the isocyanate production system. CONTENT OF THE UTILITY MODEL

[0005] Therefore, it is necessary to provide a drying device for an isocyanate production system to remove water in chlorobenzene after the system is operated.

[0006] The application provides a drying device for an isocyanate production system, which comprises a drying tower body, the drying tower body comprises an impact section and a drying section, the drying section is arranged above the impact section, the impact section is provided with a feeding nozzle at the bottom, the drying section is provided with a discharging port at the top, a gas distributor is arranged in the impact section, the gas distributor is used for spraying impact gas into the impact section, and a drying agent is arranged in the drying section.

[0007] In one of the embodiments, the gas distributor comprises a gas inlet main pipe and a plurality of gas inlet branch pipes, one end of the gas inlet main pipe is installed on the side wall of the impact section, the other end of the gas inlet main pipe is connected with the plurality of gas inlet branch pipes, the free end of the gas inlet branch pipe extends towards the central area of the impact section, and a gas outlet is arranged on the gas inlet branch pipe.

[0008] In one of the embodiments, the gas outlet comprises a first outlet arranged on the free end of the gas inlet branch pipe and / or a second outlet arranged on the side wall of the gas inlet branch pipe, and the second outlet is arranged on the side wall of the upward side of the gas inlet branch pipe.

[0009] In one of the embodiments, the gas inlet main pipe is arranged upwardly from one end close to the side wall of the impact section to the other end connected with the gas inlet branch pipe, and any of the gas inlet branch pipe is arranged upwardly from one end connected with the gas inlet main pipe to the other end.

[0010] The central axis of the main pipe is defined as a first line, and the central axes of the plurality of gas inlet branch pipes are respectively located on different conical surfaces with the first line as the central line.

[0011] In one of the embodiments, the included angle of any two adjacent gas inlet branch pipes is defined as a branch pipe included angle, and the included angles of any two adjacent branch pipe included angles are different.

[0012] In one of the embodiments, the gas distributor comprises three gas inlet branch pipes, which are respectively a first branch pipe, a second branch pipe and a third branch pipe, and the first branch pipe, the second branch pipe and the third branch pipe are sequentially adjacent, the branch pipe included angle between the first branch pipe and the second branch pipe is a first included angle, the branch pipe included angle between the second branch pipe and the third branch pipe is a second included angle, the first included angle is 30°-45°, and the second included angle is 15°-30°.

[0013] In one of the embodiments, the length of the gas inlet main pipe is L1, the inner diameter of the impact section at the position where the gas inlet main pipe is installed is D, and L=(0.01-0.05)D.

[0014] And / or, in the same gas distributor, the inner diameter of the gas inlet main pipe is D1, and the inner diameter of the gas inlet branch pipe is D2, and D2=(0.2-0.3)D1.

[0015] In one of the embodiments, the gas distributor is arranged in multiple, and the plurality of gas distributors are symmetrically arranged in the drying section with the central axis of the drying section as the central line.

[0016] In one of the embodiments, the plurality of gas distributors are arranged in at least two layers in the impact section, each layer of the gas distributors comprises at least two gas distributors, and each layer of the gas distributors is symmetrically arranged with the central axis of the drying section as the central line.

[0017] In one of the embodiments, the feed nozzle is expanded from bottom to top, and the feed nozzle is arranged at the central position of the bottom wall of the impact section.

[0018] And / or, the impact section is expanded from bottom to top.

[0019] In one of the embodiments, a feed pipe and a discharge pipe are further included, the feed pipe is communicated with the feed nozzle, a feed pump is arranged on the feed pipe, one end of the discharge pipe is connected to the bottom of the impact section, and the other end is connected with the feed pipe and located on the inlet side of the feed pump.

[0020] Compared with the prior art, the drying device provided by the application is used for removing water from the solvent circulated in the isocyanate production system before starting the vehicle. In use, the solvent circulated in the system is sprayed into the drying tower body through the feed nozzle, and the impact gas is sprayed by the gas distributor. Since the feed nozzle is arranged at the bottom of the impact section, after the solvent is sprayed from the feed nozzle, it moves upward, the impact gas sprayed by the gas distributor makes the solvent droplets collide with each other, the solvent droplets are broken into small droplets by the collision, and the solvent droplets after the collision continue to rise and enter the drying section, and then are discharged from the discharge port after the water is absorbed by the drying agent. Since the impact gas is sprayed by the gas distributor, the large droplets are broken into small droplets, so that the drying agent can more fully absorb the water carried by the solvent, thereby having a better drying effect on the solvent. After the solvent is dried by the drying device, the water content of the solvent can be less than 10 ppm, and the dried solvent then enters the isocyanate production system and then starts the vehicle, which can significantly reduce the occurrence of side reactions and obtain high-quality products. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1 Structure diagram of the drying device for the isocyanate production system according to an embodiment of the application;

[0023] Figure 2 Structure diagram of the gas distributor according to an embodiment of the application.

[0024] The drawings are as follows: 1, drying tower body; 11, impact section; 12, drying section; 121, drying agent; 13, feed nozzle; 14, discharge port; 15, feed pipe; 16, feed pump; 17, discharge pipe; 2, gas distributor; 21, gas inlet main pipe; 22, gas inlet branch pipe; 221, first branch pipe; 222, second branch pipe; 223, third branch pipe; 23, gas outlet; 231, first outlet; 232, second outlet. DETAILED DESCRIPTION

[0025] In order to make the above objectives, features and advantages of the present application more clear and comprehensible, the detailed description of the specific embodiments of the present application is made below with reference to the accompanying drawings. In the following description, a lot of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many different ways other than the one described herein, and one of ordinary skill in the art can make similar improvements without departing from the scope of the present application, and therefore the present application is not limited to the specific embodiments disclosed below.

[0026] It is to be noted that when a component is referred to as being "on" or "disposed on" another component, it can be directly on the other component or there can be intervening components present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or there can be intervening components present. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar terms as used in the description of the specification are for the purpose of illustration only and do not indicate an exclusive orientation.

[0027] In addition, the terms "first", "second", and the like, are used only to describe the features and do not imply or suggest relative importance or a number of the features indicated. Thus, the features defined with "first", "second" can include at least one of the features explicitly or implicitly. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0028] In the present application, unless otherwise explicitly specified and limited, the "on", "under", "above" and "over" of the first feature to the second feature can be that the first feature is directly in contact with the second feature, or the first feature is indirectly in contact with the second feature through an intermediate medium. Moreover, the "above", "over" and "on" of the first feature to the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "under" and "under" of the first feature to the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0029] Unless otherwise defined, all technical and scientific terms used in the specification of the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used in the specification of the present application includes any and all combinations of one or more of the related listed items.

[0030] See Figure 1 and Figure 2This application provides a drying apparatus for an isocyanate production system, including a drying tower 1. The drying tower 1 includes an impact section 11 and a drying section 12, with the drying section 12 positioned above the impact section 11. An inlet nozzle 13 is located at the bottom of the impact section 11, and an outlet 14 is located at the top of the drying section 12. A gas distributor 2 is installed inside the impact section 11 to spray impact gas into the impact section 11. A desiccant 121 is installed inside the drying section 12. This drying apparatus is used to remove water from the solvent (chlorobenzene is used as an example in this application) after it has circulated through the isocyanate production system. In use, the chlorobenzene after system operation is sprayed into the drying tower 1 through the inlet nozzle 13, and the gas distributor 2 sprays out the impact gas. Because the feed nozzle 13 is located at the bottom of the impact section 11, after chlorobenzene is ejected from the feed nozzle 13, it moves upward. The impact gas ejected from the gas distributor 2 causes the chlorobenzene droplets to collide with each other, breaking them into smaller droplets. The impacted chlorobenzene droplets continue to rise and enter the drying section 12, where the desiccant 121 absorbs the moisture before discharging from the outlet 14. The presence of the gas distributor 2 and the ejected impact gas breaks down large droplets into smaller ones, allowing the desiccant 121 to more effectively absorb the moisture carried by the chlorobenzene, resulting in a better drying effect. After drying by this device, the moisture content of the chlorobenzene can be less than 10 ppm. The dried chlorobenzene then enters the isocyanate production system for start-up, significantly reducing the occurrence of side reactions and yielding a high-quality product.

[0031] In this embodiment, the impact gas is nitrogen. Nitrogen is an inert gas and will not react with chlorobenzene. Therefore, the impact of the gas on the chlorobenzene will only cause physical changes in the chlorobenzene droplets without any chemical changes, thus preventing the introduction of new substances. Of course, the impact gas can also be other inert gases, as long as it will not react with chlorobenzene and will not react with the raw materials, products, or intermediates in the isocyanate production system.

[0032] In this embodiment, the feed nozzle 13 expands upwards, which facilitates the upward diffusion of the chlorobenzene liquid sprayed from the feed nozzle 13, allowing it to enter the drying section 12 for drying. Furthermore, the feed nozzle 13 is positioned centrally on the bottom wall of the impact section 11. This prevents the chlorobenzene droplets sprayed from the feed nozzle 13 from directly impacting the side wall of the impact section 11, reducing the likelihood of the droplets falling along the side wall after impact.

[0033] Furthermore, the impact section 11 expands from bottom to top. Since the chlorobenzene droplets ejected from the feed nozzle 13 rise in a diffused manner, this embodiment sets the impact section 11 to expand from bottom to top, making it less likely for the rising chlorobenzene droplets to hit the side wall of the impact section 11, thereby further reducing the occurrence of chlorobenzene droplets falling along the side wall of the impact section 11 after hitting it.

[0034] Further, the gas distributor 2 comprises a gas inlet main pipe 21 and a plurality of gas inlet branch pipes 22, the gas inlet main pipe 21 is installed on the side wall of the impingement section 11 at one end and is connected with the plurality of gas inlet branch pipes 22 at the other end, the free end of the gas inlet branch pipe 22 extends towards the central region of the impingement section 11, and the gas inlet branch pipe 22 is provided with a gas outlet 23. It can be understood that the impingement gas is first introduced into the gas inlet main pipe 21 of the gas distributor 2 through the pipeline, then is distributed into the plurality of gas inlet branch pipes 22, and finally is sprayed out from the gas outlet 23 to enter the inside of the impingement section 11 of the drying tower body 1, so as to impinge the rising chlorobenzene. In the embodiment, the free end of the gas inlet branch pipe 22 extends towards the central region of the impingement section 11, that is, the gas inlet branch pipe 22 extends away from the side wall of the impingement section 11, so that the impingement gas is beneficial to impinge the chlorobenzene droplets in the impingement section 11 and is not easy to impinge the chlorobenzene droplets on the side wall of the impingement section 11.

[0035] In the embodiment, the gas inlet main pipe 21 and the gas inlet branch pipe 22 are both cylindrical pipes, which are simple in structure. The gas inlet main pipe 21 is provided with a flange at the end away from the gas inlet straight pipe, and the gas inlet main pipe 21 is installed on the side wall of the impingement section 11 by being screwed or screwed into the flange.

[0036] Further, the gas outlet 23 comprises a first outlet 231 provided on the free end of the gas inlet branch pipe 22 and / or a second outlet 232 provided on the side wall of the gas inlet branch pipe 22, and the second outlet 232 is located on the side wall of the upward side of the gas inlet branch pipe 22. It can be understood that the gas outlet 23 can only comprise the first outlet 231, can only comprise the second outlet 232, or can simultaneously comprise the first outlet 231 and the second outlet 232. In the embodiment, the gas outlet 23 comprises the first outlet 231 and the second outlet 232, which has more impingement gas sprayed out, so as to be beneficial to impinge the chlorobenzene droplets into smaller droplets. The second outlet 232 is located on the side wall of the upward side of the gas inlet branch pipe 22, so that the impingement gas is sprayed out from the upward side of the gas inlet branch pipe 22, which can provide upward impingement force for the chlorobenzene droplets, and is beneficial to the upward flow of the impinged chlorobenzene droplets to enter the drying section 12.

[0037] Further, the gas inlet main pipe 21 is arranged upwardly from one end close to the side wall of the impingement section 11 to the other end connected with the gas inlet branch pipes 22, and any gas inlet branch pipe 22 is arranged upwardly from one end connected with the gas inlet main pipe 21 to the other end. The central axis of the gas inlet main pipe 21 is defined as a first line, and the central axes of the plurality of gas inlet branch pipes 22 are located on different conical surfaces with the first line as the central line. In this way, the gas inlet main pipe 21 and the gas inlet branch pipes 22 are both arranged upwardly, which is beneficial for the impinged gas to impinge upwardly on the chlorobenzene droplets, so as to provide upward impinging force to the chlorobenzene droplets, which is beneficial for the chlorobenzene droplets to rise to the drying section 12. Moreover, since the plurality of gas inlet branch pipes 22 are located on different conical surfaces, the chlorobenzene droplets near the gas distributor 2 can be impinged by the impinged gas on different gas inlet branch pipes 22, which is beneficial for the chlorobenzene droplets to be dispersed into smaller droplets, thereby facilitating the drying of the chlorobenzene.

[0038] Further, the included angle between any two adjacent gas inlet branch pipes 22 is defined as a branch pipe included angle, and the included angles of any two adjacent branch pipe included angles are different. In this way, the chlorobenzene droplets near the gas distributor 2 can be impinged by the impinged force in asymmetric directions, so as to make the chlorobenzene droplets into smaller droplets, thereby facilitating the further removal of the moisture in the chlorobenzene.

[0039] Please refer to Figure 2 In an embodiment, the gas distributor 2 includes three gas inlet branch pipes 22, which are a first branch pipe 221, a second branch pipe 222 and a third branch pipe 223, and the first branch pipe 221, the second branch pipe 222 and the third branch pipe 223 are sequentially adjacent. The branch pipe included angle between the first branch pipe 221 and the second branch pipe 222 is a first included angle θ1, the branch pipe included angle between the second branch pipe 222 and the third branch pipe 223 is a second included angle θ2, the first included angle θ1 is 30°-45°, and the second included angle θ2 is 15°-30°.

[0040] The number of the gas inlet branch pipes 22 can be 3-5, which is not limited in the present application, wherein the sum of the branch pipe included angles is less than 90°.

[0041] The length of the gas inlet main pipe 21 is too long, which causes the gas inlet branch pipe 22 of the gas distributor 2 to have a narrow impact range and a large dead zone, in which liquid drops cannot be impacted by the impact force and fall to the bottom of the drying tower body 1. In addition, the gas inlet main pipe 21 needs to have a certain length to facilitate the connection between the gas inlet main pipe 21 and the side wall of the drying tower body 1 by bolts or screws. Further, the length of the gas inlet main pipe 21 is L, the inner diameter of the impact section where the gas inlet main pipe is installed is D, and L=(0.01-0.05)D. In this way, the length of the gas inlet main pipe 21 is moderate, which makes the impact range of the gas inlet branch pipe 22 larger, reduces the dead zone, and facilitates the connection between the gas inlet main pipe 21 and the side wall of the drying tower body 1. Further, in the same gas distributor, the inner diameter of the gas inlet main pipe 21 is D1, and the inner diameter of the gas inlet branch pipe 22 is D2, and D2=(0.2-0.3)D1. In this way, the impact gas sprayed from the gas outlet 23 of the gas inlet branch pipe 22 has a larger coverage range, and the chlorobenzene liquid drops in the impact section 11 can be basically impacted by the impact gas, thereby forming smaller liquid drops. In an embodiment, D2=0.25D1.

[0042] Further, the gas distributor 2 is provided in multiple numbers, and the multiple gas distributors 2 are symmetrically arranged in the drying section 12 with the central axis of the drying section 12 as the center line. The symmetric arrangement of the multiple gas distributors 2 can make the chlorobenzene liquid drops in the impact section 11 subjected to a symmetric force, thereby facilitating the upward movement of the chlorobenzene liquid drops and reducing the situation that the impact gas impacts the chlorobenzene liquid drops to the side wall of the impact section 11.

[0043] Further, the multiple gas distributors 2 are arranged in at least two layers in the impact section 11, each layer of gas distributors 2 includes at least two gas distributors 2, and the gas distributors 2 in each layer are symmetrically arranged with the central axis of the drying section 12 as the center line. In this way, the impact gas sprayed from the at least two layers of gas distributors 2 can provide the chlorobenzene liquid drops with the power to move upward, thereby facilitating the upward movement of the chlorobenzene liquid drops to the drying section 12 for drying.

[0044] In the present embodiment, the gas distributor 2 is provided in four numbers, and the four gas distributors 2 are arranged in two layers in the impact section 11, and each layer includes two gas distributors 2. The two gas distributors 2 in the lower layer are symmetrically arranged at the lower end of the impact section 11, and the two gas distributors 2 in the upper layer are symmetrically arranged at the upper end of the impact section 11.

[0045] As shown in FIG. 1, the drying section 12 is in a cylindrical shape, and the drying section 12 is provided with a drying bed, which includes a screen and drying agents 121 arranged in the screen. The drying agents 121 are in the form of granular drying agents 121. Further, the drying agents 121 are one or more of anhydrous calcium chloride, anhydrous sodium sulfate, and anhydrous copper sulfate, which are not limited in the present application. The height of the drying bed is 0.5-2 cm, which is conducive to the full absorption of the moisture carried by the chlorobenzene by the drying agents 121, thereby making the moisture content of the chlorobenzene lower after passing through the drying device. Figure 1 As shown in FIG. 1, the drying section 12 is in a cylindrical shape, and the drying section 12 is provided with a drying bed, which includes a screen and drying agents 121 arranged in the screen. The drying agents 121 are in the form of granular drying agents 121. Further, the drying agents 121 are one or more of anhydrous calcium chloride, anhydrous sodium sulfate, and anhydrous copper sulfate, which are not limited in the present application. The height of the drying bed is 0.5-2 cm, which is conducive to the full absorption of the moisture carried by the chlorobenzene by the drying agents 121, thereby making the moisture content of the chlorobenzene lower after passing through the drying device.

[0046] It can be understood that the drying device further comprises a feeding pipe 15, and a feeding pump 16 is arranged on the feeding pipe 15, so that the feeding pump 16 can pump the chlorobenzene into the drying tower body 1. Further, the drying device further comprises a discharging pipe 17, one end of the discharging pipe 17 is connected to the bottom of the impact section 11, and the other end is connected with the feeding pipe 15 and located on the inlet side of the feeding pump 16. In this way, the chlorobenzene droplets falling in the impact section 11 by impact can be sprayed into the impact section 11 again through the feeding pump 16 and the feeding nozzle 13, so as to ensure that the chlorobenzene droplets are fully dried, and finally discharged from the discharge port 14.

[0047] Further, the impact gas flowing into the gas distributor 2 is hot nitrogen gas, which is beneficial to the vaporization of water in the chlorobenzene droplets, so as to further improve the water removal efficiency of the chlorobenzene.

[0048] It can be understood that the feeding pipe 15 can be preheated by hot nitrogen gas, and the chlorobenzene is sprayed into the drying tower body 1 by heating, which is beneficial to the vaporization of chlorobenzene and the upward movement of chlorobenzene in the drying tower body 1, so as to further improve the water removal efficiency of the chlorobenzene. The drying device dries the chlorobenzene, and finally hot nitrogen gas is introduced into the feeding pipe 15 to clean the residual chlorobenzene. The water content of the chlorobenzene discharged from the discharge port 14 after being treated by the drying device can be less than 10 ppm, and the dried chlorobenzene is then introduced into the isocyanate production system and then started, which can significantly reduce the occurrence of side reactions and obtain high-quality products.

[0049] The technical features of the above-mentioned embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above-mentioned embodiments are not described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the description.

[0050] The above-mentioned embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that for ordinary skilled persons in the art, some modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A drying device for an isocyanate production system, characterized by, The dryer comprises a drying tower body, which comprises an impact section and a drying section arranged above the impact section, The bottom of the impact section is provided with a feed nozzle, and the top of the drying section is provided with a discharge port, The impact section is provided with a gas distributor for spraying impact gas into the impact section, The drying section is provided with a drying agent.

2. The drying apparatus for an isocyanate production system according to claim 1, characterized by, The gas distributor comprises a gas inlet main pipe and a plurality of gas inlet branch pipes, one end of the gas inlet main pipe is mounted on the side wall of the impact section, the other end is connected to the plurality of gas inlet branch pipes, the free end of the gas inlet branch pipe extends towards the central area of the impact section, and the gas inlet branch pipe is provided with a gas outlet.

3. The drying apparatus for an isocyanate production system according to claim 2, characterized by, The gas outlet comprises a first outlet arranged at the free end of the gas inlet branch pipe and / or a second outlet arranged on the side wall of the gas inlet branch pipe, and the second outlet is located on the upward side wall of the gas inlet branch pipe.

4. The drying apparatus for an isocyanate production system according to claim 2, characterized by The gas inlet main pipe is inclined upward from one end close to the side wall of the impact section to the end connected to the gas inlet branch pipe, and any gas inlet branch pipe is inclined upward from one end connected to the gas inlet main pipe to the other end, The central axis of the main pipe is defined as a first line, and the central axes of the plurality of gas inlet branch pipes are located on different conical surfaces with the first line as the central line.

5. The drying apparatus for an isocyanate production system according to claim 4, characterized by The included angle of any two adjacent gas inlet branch pipes is defined as a branch pipe included angle, and the angles of any two adjacent branch pipe included angles are different.

6. The drying apparatus for an isocyanate production system according to claim 5, characterized by The gas distributor comprises three gas inlet branch pipes, which are respectively a first branch pipe, a second branch pipe and a third branch pipe, and the first branch pipe, the second branch pipe and the third branch pipe are sequentially adjacent, the branch pipe included angle between the first branch pipe and the second branch pipe is a first included angle, the branch pipe included angle between the second branch pipe and the third branch pipe is a second included angle, the first included angle is 30°-45°, and the second included angle is 15°-30°.

7. The drying apparatus for an isocyanate production system according to claim 2, characterized by The length of the gas inlet main pipe is L, the inner diameter of the impact section where the gas inlet main pipe is mounted is D, and L=(0.01-0.05)D; And / or, in the same gas distributor, the inner diameter of the gas inlet main pipe is D1, the inner diameter of the gas inlet branch pipe is D2, and D2=(0.2-0.3)D1.

8. The drying apparatus for an isocyanate production system according to claim 1, characterized by, The gas distributor is provided in multiple, and the plurality of gas distributors are symmetrically arranged in the drying section with the central axis of the drying section as the central line.

9. The drying apparatus for an isocyanate production system according to claim 8, characterized by, The plurality of gas distributors are arranged in at least two layers in the impact section, each layer of the gas distributors comprises at least two gas distributors, and each layer of the gas distributors is symmetrically arranged with the central axis of the drying section as the central line.

10. The drying apparatus for an isocyanate production system according to claim 1, characterized by, The feed nozzle is expanded from bottom to top, and the feed nozzle is arranged at the central position of the bottom wall of the impact section. And / or, the impact section is expanded from bottom to top.

11. The drying apparatus for an isocyanate production system according to claim 1, characterized by, It also comprises a feed pipe and a discharge pipe, the feed pipe is connected to the feed nozzle, the feed pipe is provided with a feed pump, one end of the discharge pipe is connected to the bottom of the impact section, the other end is connected to the feed pipe and located on the inlet side of the feed pump.

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