Static mixer and nitrobenzene liquid alkali washing method

Abstract

The invention relates to the technical field of nitrobenzene alkali washing, in particular to a static mixer and a nitrobenzene liquid alkali washing method. The static mixer comprises an outer shell, a mixing cavity is formed in the outer shell, a first liquid inlet is formed in the head end of the outer shell, and a mixed liquid outlet is formed in the tail end of the outer shell; the conveying pipe penetrates through the mixing cavity from the head end of the outer shell and extends to the tail end of the outer shell, a first port of the conveying pipe extends out of the outer shell and forms a second liquid inlet, a second port of the conveying pipe is closed, the part, located in the mixing cavity, of the conveying pipe forms a spraying section, and a plurality of spraying holes distributed at intervals are formed in the pipe wall of the spraying section; a first spiral blade and a second spiral blade which are distributed at intervals in the axial direction of the spraying section are arranged on the periphery of the spraying section, and the spiral directions of the first spiral blade and the second spiral blade are opposite. According to the static mixer, acid liquor in nitrobenzene liquid can be effectively contacted with alkali liquor, so that the use amount of the alkali liquor is reduced, the alkali consumption is reduced, and the alkali washing effect is improved.

Description

Technical Field

[0001] This invention relates to the field of nitrobenzene alkaline washing technology, specifically to a static mixer and a liquid nitrobenzene alkaline washing method. Background Technology

[0002] Nitrobenzene, an important industrial chemical, is commonly used as an intermediate in organic synthesis and a raw material for the production of aniline. It is typically produced by the nitration reaction of benzene with a mixture of nitric acid and sulfuric acid. The nitrobenzene liquid produced by nitration contains acid, but since nitrobenzene is an oily liquid insoluble in water, the acid is dispersed in the form of small droplets, which are then encapsulated by the nitrobenzene liquid, creating a "water-in-oil" emulsion. Before proceeding to the next stage of processing, the nitrobenzene liquid needs to be purified by alkaline washing with an alkaline solution to remove impurities such as acid and nitrophenol.

[0003] Alkali washing of nitrobenzene liquid is primarily performed through static mixing. A traditional static mixer consists of a housing containing a mixing chamber. Inside the mixing chamber are multiple alternating agitator plates. The housing has a first inlet and a second inlet at its front end, and a mixture outlet at its rear end. Nitrobenzene liquid and alkali solution enter the mixing chamber through the first and second inlets, respectively. Under the agitation of the agitator plates, the nitrobenzene liquid and alkali solution mix during flow, thereby neutralizing the acid in the nitrobenzene liquid. However, to maintain sufficient flow capacity at the mixture outlet, the agitator plate distribution density is low, and the spacing between adjacent agitator plates is large. This reduces the agitation effect, making it difficult for acid droplets to effectively contact and neutralize the alkali solution. Therefore, only by increasing the amount of alkali solution used can all the acid in the nitrobenzene liquid be completely removed.

[0004] Therefore, the mixing effect of alkali solution and nitrobenzene liquid in traditional static mixers is poor, resulting in increased alkali consumption. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of poor mixing effect of traditional static mixers on alkaline solutions and nitrobenzene liquids in the prior art.

[0006] To achieve the above objectives, the present invention provides a static mixer comprising: an outer shell, the interior of which is provided with a mixing chamber, a first liquid inlet at the front end of the outer shell for the raw material liquid to enter the mixing chamber, and a mixing outlet at the rear end of the outer shell for the mixed liquid to flow out of the mixing chamber; and a conveying pipe extending from the front end of the outer shell through the mixing chamber to the rear end of the outer shell, a first port at the front end of the conveying pipe extending out of the outer shell and forming a second liquid inlet, a second port at the rear end of the conveying pipe being closed, a portion of the conveying pipe located in the mixing chamber forming a spray section, the wall of the spray section being provided with a plurality of spaced-apart spray holes for spraying the cleaning liquid input through the second liquid inlet into the mixing chamber, and the outer periphery of the spray section being provided with a first helical blade and a second helical blade spaced-apart along its axial direction, the helical directions of the first helical blade and the second helical blade being opposite.

[0007] In some embodiments, the mixing chamber includes a first variable diameter region, a buffer zone, and a second variable diameter region distributed sequentially along the direction from the first liquid inlet to the mixture outlet, with the first helical blade and the second helical blade located in the first variable diameter region and the second variable diameter region, respectively; and / or, the outer shell is cylindrical, with the axial direction of the first liquid inlet perpendicular to the axial direction of the outer shell, and the axial direction of the mixture outlet being the same as that of the outer shell.

[0008] In some embodiments, the first variable diameter zone includes a first mixing section, a first expansion section, and a first contraction section sequentially distributed along the axial direction of the injection section. The first mixing section is connected to the first liquid inlet, and the first contraction section is connected to the buffer zone. The diameter of the first contraction section gradually decreases along the direction from the first liquid inlet to the mixed liquid outlet. The minimum diameter of the first contraction section is the same as the diameter of the buffer zone, the maximum diameter of the first contraction section is the same as the diameter of the first expansion section, and the diameter of the first expansion section is greater than the diameter of the first mixing section.

[0009] In some embodiments, there is a first radial distance between the wall of the first mixing section and the outer edge of the first helical blade, the minimum radial distance between the wall of the first tapering section and the outer edge of the first helical blade is a second radial distance, and there is a third radial distance between the outer wall of the spray section and the wall of the first mixing section. The first radial distance and the second radial distance are 1 / 8 to 1 / 4 of the third radial distance.

[0010] In some embodiments, the wall surface of the first expansion section is provided with a first helical line-shaped ridge surrounding the first helical blade, and the helical direction of the first helical line-shaped ridge is opposite to the helical direction of the first helical blade.

[0011] In some embodiments, the axial length of the buffer is less than or equal to the axial length of the first mixing segment.

[0012] In some embodiments, the axial length of the second variable diameter region is less than the axial length of the first variable diameter region; the second variable diameter region includes a second mixing section, a second expansion section, and a second contraction section distributed sequentially along the axial direction of the injection section; the second mixing section is connected to the buffer zone, and the second contraction section is connected to the mixed liquid outlet; the diameter of the second contraction section gradually decreases along the direction from the second liquid inlet to the mixed liquid outlet; the minimum diameter of the second contraction section is the same as the diameter of the mixed liquid outlet; the maximum diameter of the second contraction section is the same as the diameter of the second expansion section; the diameter of the second expansion section is greater than the diameter of the second mixing section; and the diameter of the second mixing section is equal to the diameter of the buffer zone.

[0013] In some embodiments, there is a fourth radial spacing between the wall of the second mixing section and the outer edge of the second helical blade, a minimum radial spacing between the wall of the second tapering section and the outer edge of the second helical blade is a fifth radial spacing, and a sixth radial spacing between the outer wall of the injection section and the wall of the second mixing section. The fourth and fifth radial spacings are 1 / 8 to 1 / 4 of the sixth radial spacing.

[0014] In some embodiments, the wall surface of the second expansion section is provided with a second helical ridge surrounding the second helical blade, and the helical direction of the second helical ridge is opposite to the helical direction of the second helical blade.

[0015] In some embodiments, all injection holes are distributed in multiple rows and columns on the injection section, and the number of injection holes in the first diameter change zone is greater than the number of injection holes in the second diameter change zone; in the axial direction of the injection section, the spacing between two adjacent injection holes in the buffer zone is smaller than the spacing between two adjacent injection holes in the second diameter change zone.

[0016] In some embodiments, the diameter of the injection hole gradually decreases from its inlet end to its outlet end, and the wall of the injection hole is provided with a third spiral-shaped ridge distributed around the axis of the injection hole. The injection hole extends obliquely towards the head end of the housing from its inlet end to its outlet end.

[0017] Another aspect of the present invention provides a liquid nitrobenzene alkaline washing method, which includes: guiding a liquid nitrobenzene containing acid to flow forward spirally along a first spiral trajectory, and then guiding the liquid nitrobenzene to flow forward spirally along a second spiral trajectory, wherein the spiral direction of the first spiral trajectory is opposite to the spiral direction of the second spiral trajectory; and simultaneously spraying alkaline solution into the forward-flowing liquid nitrobenzene.

[0018] In some embodiments, the nitrobenzene liquid alkaline washing method is carried out using the static mixer described above.

[0019] The technical solution of the present invention has the following beneficial effects:

[0020] Acid-containing nitrobenzene liquid enters the mixing chamber through the first liquid inlet, while alkali solution enters the injection section of the delivery pipe through the second liquid inlet. The alkali solution is then injected into the nitrobenzene solution within the mixing chamber through injection holes, where it mixes with the acid-containing nitrobenzene liquid to form a mixture. On one hand, the mixture flows spirally along the first and second helical blades. This spiral flow creates a tangential velocity and a shear stress gradient within the mixture, causing the alkali solution to be sheared and broken into small droplets. This allows the alkali solution to be fully mixed with the nitrobenzene liquid and neutralized with the acid during the rotating flow. On the other hand, as the mixture leaves the area containing the first helical blade and begins to enter the area containing the second helical blade, the flow state of the mixture changes drastically due to the different helical directions of the first and second helical blades, creating intense turbulence. This further allows the alkali solution to be more thoroughly mixed with the nitrobenzene liquid and neutralized with the acid. Therefore, the static mixer of the present invention can fully mix the nitrobenzene liquid and the alkaline solution, thereby enabling the acid in the nitrobenzene liquid to come into effective contact with the alkaline solution, thereby reducing the amount of alkaline solution used, reducing alkali consumption, and reducing impurities such as nitrophenol in the product, thereby improving the alkaline washing effect. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of a static mixer in one embodiment of the present invention;

[0022] Figure 2 This is a cross-sectional schematic diagram of the outer shell in one embodiment of the present invention;

[0023] Figure 3 yes Figure 2 An enlarged schematic diagram of part A in the middle;

[0024] Figure 4 yes Figure 2 Enlarged schematic diagram of part B in the middle;

[0025] Figure 5 This is a schematic diagram of the distribution of the third spiral-shaped convex pattern in one embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures

[0027] 1. Outer shell; 11. Mixing chamber; 12. First liquid inlet; 13. Mixed liquid outlet; 14. First diameter changing zone; 141. First mixing section; 142. First expansion section; 143. First tapering section; 144. First spiral-shaped ridge; 15. Buffer zone; 16. Second diameter changing zone; 161. Second mixing section; 162. Second expansion section; 163. Second tapering section; 164. Second spiral-shaped ridge;

[0028] 2. Delivery pipe; 21. Injection section; 22. Second liquid inlet; 23. Injection hole; 24. First helical blade; 25. Second helical blade; 26. Third helical ridge. Detailed Implementation

[0029] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present invention and not to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the invention.

[0030] like Figure 1 and Figure 2 As shown, the present invention provides a static mixer, which includes a housing 1 and a delivery pipe 2. The housing 1 has a mixing chamber 11 inside. The first end of the housing 1 has a first liquid inlet 12 for the raw material liquid to enter the mixing chamber 11, and the last end of the housing 1 has a mixing outlet 13 for the mixed liquid to flow out of the mixing chamber 11. The delivery pipe 2 extends from the first end of the housing 1 through the mixing chamber 11 to the last end of the housing 1. The first port of the delivery pipe 2 at the first end extends outside the housing 1 and forms a second liquid inlet 22. The second port of the delivery pipe 2 at the last end is closed. The portion of the delivery pipe 2 located in the mixing chamber 11 forms a spray section 21. The wall of the spray section 21 has a plurality of spaced-apart spray holes 23 for spraying the cleaning liquid input through the second liquid inlet 22 into the mixing chamber 11. The outer periphery of the spray section 21 has first helical blades 24 and second helical blades 25 spaced-apart along its axial direction, with the helical directions of the first helical blades 24 and the second helical blades 25 being opposite.

[0031] Specifically, nitrobenzene liquid containing acid can enter the mixing chamber 11 through the first liquid inlet 12, and alkali solution can enter the injection section 21 of the delivery pipe 2 through the second liquid inlet 22. The alkali solution is then sprayed from the injection hole 23 into the nitrobenzene solution in the mixing chamber 11, where the acid-containing nitrobenzene liquid mixes with the alkali solution to form a mixture. On one hand, the mixture flows spirally along the first helical blade 24 and the second helical blade 25. This spiral flow has a tangential velocity, and a shear stress gradient is formed within the mixture, causing the alkali solution to be sheared and broken into small droplets. This allows the alkali solution to be fully mixed in the nitrobenzene liquid and neutralized with the acid solution during the rotating flow. On the other hand, when the mixture leaves the area where the first helical blade 24 is located and begins to enter the area where the second helical blade 25 is located, the flow state of the mixture changes drastically due to the different helical directions of the first and second helical blades 24 and 25, forming intense turbulence. This further allows the alkali solution to be fully mixed in the nitrobenzene liquid and neutralized with the acid solution. Therefore, the static mixer of the present invention can fully mix the nitrobenzene liquid and the alkaline solution, thereby enabling the acid in the nitrobenzene liquid to come into effective contact with the alkaline solution, thereby reducing the amount of alkaline solution used, reducing alkali consumption, and reducing impurities such as nitrophenol in the product, thereby improving the alkaline washing effect.

[0032] In some embodiments, the helical direction of the first helical blade 24 is towards the first liquid inlet 12, and the helical direction of the first helical blade 24 is towards the mixture outlet 13. In other embodiments, the helical direction of the first helical blade 24 is towards the mixture outlet 13, and the helical direction of the first helical blade 24 is towards the first liquid inlet 12.

[0033] like Figure 1 and Figure 2 As shown, in some embodiments of the present invention, the mixing chamber 11 includes a first variable diameter region 14, a buffer zone 15 and a second variable diameter region 16 distributed sequentially along the direction from the first liquid inlet 12 to the mixed liquid outlet 13, and the first helical blade 24 and the second helical blade 25 are respectively located in the first variable diameter region 14 and the second variable diameter region 16.

[0034] Specifically, the first variable diameter region 14 and the second variable diameter region 16 may include multiple sections with different diameters. The flow state of the mixture in the first variable diameter region 14 and the second variable diameter region 16 will continuously change, thereby facilitating the mixing between nitrobenzene liquid and alkali solution.

[0035] like Figure 1 and Figure 2 As shown, in some embodiments of the present invention, the outer shell 1 is cylindrical, the axial direction of the first liquid inlet 12 is perpendicular to the axial direction of the outer shell 1, and the axial direction of the mixed liquid outlet 13 is the same as that of the outer shell 1.

[0036] Specifically, when the nitrobenzene liquid enters the mixing chamber 11 from the first liquid inlet 12, the nitrobenzene liquid undergoes a change in direction, resulting in turbulence, which helps to fully mix the alkali solution into the nitrobenzene liquid. In some embodiments, the ratio of the length of the first helical blade 24 to the axial length of the first diameter-changing region 14 is (0.9 to 1):1. Preferably, the length of the first helical blade 24 is the same as the axial length of the first diameter-changing region 14. In some embodiments, the ratio of the length of the second helical blade 25 to the axial length of the second diameter-changing region 16 is (0.9 to 1):1. Preferably, the length of the second helical blade 25 is the same as the axial length of the second diameter-changing region 16.

[0037] like Figure 1 and Figure 2 As shown, in some embodiments of the present invention, the first variable diameter zone 14 includes a first mixing section 141, a first expansion section 142, and a first contraction section 143 sequentially distributed along the axial direction of the injection section 21. The first mixing section 141 communicates with the first liquid inlet 12, and the first contraction section 143 communicates with the buffer zone 15. The diameter of the first contraction section 143 gradually decreases along the direction from the first liquid inlet 12 to the mixed liquid outlet 13. The minimum diameter of the first contraction section 143 is the same as the diameter of the buffer zone 15, and the maximum diameter of the first contraction section 143 is the same as the diameter of the first expansion section 142. The diameter of the first expansion section 142 is larger than the diameter of the first mixing section 141.

[0038] Specifically, the first mixing section 141 is cylindrical, thus having a uniform diameter. This results in a relatively stable flow environment for the mixture, facilitating a spiral flow guided by the first helical blades 24. During this spiral flow, the mixture exhibits tangential velocity and generates a shear stress gradient, causing the alkali solution to be sheared and broken into small droplets. This allows the alkali solution to be fully mixed with the nitrobenzene liquid and neutralized with the acid during the rotating flow. The first expansion section 142 is also cylindrical, resulting in a uniform diameter, but its diameter is larger than that of the first mixing section 141. As the diameter of the first expansion section 142 suddenly increases, the flow velocity of the mixture in the first expansion section 142 drops sharply, while the pressure increases. At this time, the flow velocity of the mixture near the wall of the first expansion section 142 is low, while the flow velocity of the mixture near the injection section 21 is high, that is, a large velocity difference is formed in the first expansion section 142. This velocity difference can cause a violent secondary eddy in the mixture in the first expansion section 142. This secondary eddy breaks up and mixes the alkali solution, so that the alkali solution is fully mixed in the nitrobenzene liquid and neutralized with the acid solution. The diameter of the first tapering section 143 gradually decreases, so the flow velocity of the mixture in the first tapering section gradually increases. On the one hand, this prevents the alkali solution droplets from agglomerating and growing; on the other hand, it promotes the accelerated collision and neutralization of the acid and alkali solutions under high-speed flow; and on the other hand, it ensures that the mixture has a large flow velocity before entering the second diameter-changing section 16 (which facilitates the formation of violent turbulence in the buffer zone 15). In addition, the first helical blade 24 can guide the mixture to maintain a helical flow in the first variable diameter zone 14, which also facilitates the formation of intense turbulence in the buffer zone 15.

[0039] like Figure 1 As shown, in some embodiments of the present invention, there is a first radial distance between the wall of the first mixing section 141 and the outer edge of the first helical blade 24, the minimum radial distance between the wall of the first tapering section 143 and the outer edge of the first helical blade 24 is a second radial distance, and there is a third radial distance between the outer wall of the injection section 21 and the wall of the first mixing section 141. The first radial distance and the second radial distance are 1 / 8 to 1 / 4 of the third radial distance.

[0040] Specifically, the distance between the wall of the first mixing section 141 and the outer edge of the first helical blade 24 is small, and the minimum radial distance between the wall of the first tapering section 143 and the outer edge of the first helical blade 24 is also small, so that all the mixture in the first variable diameter section 14 can flow spirally along the first helical blade 24.

[0041] like Figure 3As shown, in some embodiments of the present invention, the wall surface of the first expansion section 142 is provided with a first spiral line-shaped ridge 144 surrounding the first spiral blade 24, and the spiral direction of the first spiral line-shaped ridge 144 is opposite to the spiral direction of the first spiral blade 24.

[0042] Specifically, the first spiral-shaped ridge 144 applies reverse resistance to the liquid, causing the flow velocity of the mixture at the wall of the first expansion section 142 to decrease, and also increasing the velocity difference in the first expansion section 142, increasing the intensity of the secondary eddy, and further promoting the breaking and mixing of the alkali solution.

[0043] In some embodiments, the radially inner surface of the first helical ridge 144 is located between the wall of the first expansion section 142 and the wall of the first mixing section 141, and the thickness of the first helical ridge 144 is less than or equal to the wall thickness of the conveying pipe 2.

[0044] In some embodiments of the present invention, the axial length of the buffer 15 is less than or equal to the axial length of the first mixing segment 141.

[0045] Specifically, when the mixture flows from the first variable diameter section 14 to the second variable diameter section 16, because the helical direction of the first helical blade 24 is opposite to that of the second helical blade 25, the liquid needs to change its helical flow direction to flow along the second helical blade 25. In addition, the liquid will have a large flow velocity after being accelerated in the first tapering section 143. Therefore, the flow state of the mixture in the buffer zone 15 will change drastically. This drastic change will disrupt the original flow state of the acid, alkali and nitrobenzene liquids and form intense turbulence, promoting full contact between the acid and alkali. However, the axial length of the buffer zone 15 should not be too long, so that the turbulence can be concentrated and the acid and alkali can be fully contacted in a relatively compact area.

[0046] In some embodiments of the present invention, the axial length of the second variable diameter region 16 is less than the axial length of the first variable diameter region 14. The second variable diameter region 16 includes a second mixing section 161, a second expansion section 162, and a second contraction section 163, which are sequentially distributed along the axial direction of the injection section 21. The second mixing section 161 communicates with the buffer zone 15, and the second contraction section 163 communicates with the mixed liquid outlet 13. The diameter of the second contraction section 163 gradually decreases along the direction from the second liquid inlet 22 to the mixed liquid outlet 13. The minimum diameter of the second contraction section 163 is the same as the diameter of the mixed liquid outlet 13, and the maximum diameter of the second contraction section 163 is the same as the diameter of the second expansion section 162. The diameter of the second expansion section 162 is greater than the diameter of the second mixing section 161, and the diameter of the second mixing section 161 is equal to the diameter of the buffer zone 15.

[0047] Specifically, the second variable diameter zone 16 is closer to the mixture outlet 13, so the time for the mixture to flow from the second variable diameter zone 16 to the mixture outlet 13 is relatively short, which is not conducive to the thorough mixing of the acid and alkali solutions. Therefore, the length of the second variable diameter zone 16 can be relatively short. The second mixing section 161 is cylindrical, so it has a consistent diameter, resulting in a relatively stable flow environment for the mixture. This facilitates the formation of a spiral flow in the mixture within the second mixing section 161 under the guidance of the second helical blade 25. During the spiral flow of the mixture, it has a tangential velocity, and a shear stress gradient is formed, causing the alkali solution to be sheared and broken into small droplets. This allows the alkali solution to be fully mixed in the nitrobenzene liquid and neutralized with the acid solution during the rotating flow. The second expansion section 162 is cylindrical, so it has a consistent diameter, but its diameter is larger than that of the second mixing section 161. As the diameter of the second expansion section 162 suddenly increases, the flow velocity of the mixture in the second expansion section 162 drops abruptly, while the pressure increases. At this time, the flow velocity of the mixture near the wall of the second expansion section 162 is low, while the flow velocity of the mixture near the injection section 21 is high, thus creating a large velocity difference in the second expansion section 162. This velocity difference enables the mixture in the second expansion section 162 to generate intense secondary eddies. These secondary eddies break up and mix the alkali solution, ensuring that the alkali solution is fully mixed in the nitrobenzene liquid and neutralized with the acid solution. The diameter of the second contraction section 163 gradually decreases, so the flow velocity of the mixture in the second contraction section gradually increases. On the one hand, this prevents the alkali solution droplets from agglomerating and growing; on the other hand, it promotes the accelerated collision and neutralization of the acid and alkali solutions under high-speed flow.

[0048] like Figure 1 As shown, in some embodiments of the present invention, there is a fourth radial distance between the wall of the second mixing section 161 and the outer edge of the second helical blade 25, the minimum radial distance between the wall of the second tapering section 163 and the outer edge of the second helical blade 25 is a fifth radial distance, and there is a sixth radial distance between the outer wall of the injection section 21 and the wall of the second mixing section 161. The fourth and fifth radial distances are 1 / 8 to 1 / 4 of the sixth radial distance.

[0049] Specifically, the distance between the wall of the second mixing section 161 and the outer edge of the second helical blade 25 is small, and the minimum radial distance between the wall of the second tapering section 163 and the outer edge of the second helical blade 25 is also small, so that all the mixture in the second variable diameter section 16 can flow spirally along the second helical blade 25.

[0050] like Figure 4As shown, in some embodiments of the present invention, the wall surface of the second expansion section 162 is provided with a second spiral line-shaped ridge 164 surrounding the second spiral blade 25, and the spiral direction of the second spiral line-shaped ridge 164 is opposite to the spiral direction of the second spiral blade 25.

[0051] Specifically, the second spiral-shaped ridge 164 applies reverse resistance to the liquid, causing the flow velocity of the mixture at the wall of the second expansion section 162 to decrease, and also increasing the velocity difference in the second expansion section 162, increasing the intensity of the secondary eddy, and further promoting the breaking and mixing of the alkali solution.

[0052] In some embodiments, the radially inner surface of the second helical ridge 164 is located between the wall surface of the second expansion section 162 and the wall surface of the second mixing section 161, and the thickness of the second helical ridge 164 is less than or equal to the wall thickness of the delivery pipe 2.

[0053] In some embodiments of the present invention, all the injection holes 23 are distributed in multiple rows and columns on the injection section 21 to enable the injection of the mixture into various regions of the mixing chamber 11. The second diameter-changing zone 16 is closer to the mixture outlet 13, so the time for the mixture to flow from the second diameter-changing zone 16 to the mixture outlet 13 is relatively short, which is not conducive to sufficient mixing of the acid and alkali solutions. Therefore, the number of injection holes 23 in the second diameter-changing zone 16 can be relatively smaller, while the number of injection holes 23 in the first diameter-changing zone 14 can be relatively larger. That is, the number of injection holes 23 in the first diameter-changing zone 14 is greater than the number of injection holes 23 in the second diameter-changing zone 16, so that more alkali solution can be fully mixed in the first diameter-changing zone 14 and the buffer zone 15, reducing the amount of alkali solution used. Simultaneously, in the axial direction of the injection section 21, the distance between two adjacent injection holes 23 in the buffer zone 15 is smaller than the distance between two adjacent injection holes 23 in the second diameter-changing zone 16, so the distribution density of the injection holes 23 in the buffer zone 15 is relatively high, allowing the injection pipe to inject more alkali solution into the buffer zone 15. Because of the intense turbulence in buffer zone 15, acid and alkali solutions come into contact more easily, so spraying more alkali solution into buffer zone 15 helps to remove acid as quickly as possible.

[0054] like Figure 5 As shown, in some embodiments of the present invention, the diameter of the injection hole 23 gradually decreases from its liquid inlet end to its liquid outlet end, and the wall of the injection hole 23 is provided with a third spiral-shaped ridge 26 distributed around the axis of the injection hole 23. The injection hole 23 extends obliquely towards the first end of the outer casing 1 from its liquid inlet end to its liquid outlet end.

[0055] Specifically, the injection hole 23 is a tapered hole, which accelerates the alkali solution to a certain extent, increasing the impact of the alkali solution on the mixture in the mixing chamber 11 and increasing the disturbance to the mixture. At the same time, the third spiral ridge 26 can guide the alkali solution to flow in a spiral manner, further increasing the disturbance to the mixture, so as to ensure that the acid and alkali solutions are fully mixed.

[0056] Another aspect of the present invention provides a liquid nitrobenzene alkaline washing method, which includes: guiding a liquid nitrobenzene containing acid to flow forward spirally along a first spiral trajectory, and then guiding the liquid nitrobenzene to flow forward spirally along a second spiral trajectory, wherein the spiral direction of the first spiral trajectory is opposite to the spiral direction of the second spiral trajectory; and simultaneously spraying alkaline solution into the forward-flowing liquid nitrobenzene.

[0057] Specifically, during the flow of nitrobenzene liquid containing acid, an alkaline solution is injected into the nitrobenzene liquid to form a forward-flowing mixture. The mixture is guided to flow forward spirally along a first helical trajectory. This spirally flowing mixture has a tangential velocity, and a shear stress gradient is formed within the mixture, causing the alkaline solution to be sheared and broken into small droplets. This allows the alkaline solution to be fully mixed in the nitrobenzene liquid and neutralized with the acid during the swirling flow. Before the mixture begins to flow forward spirally along a second helical trajectory, the flow state of the mixture changes drastically due to the opposite helical directions of the first and second helical trajectories, creating intense turbulence. This further allows the alkaline solution to be fully mixed in the nitrobenzene liquid and neutralized with the acid. When the mixture is guided to flow forward spirally along the second helical trajectory, the spirally flowing mixture has a tangential velocity, and a shear stress gradient is formed within the mixture, causing the alkaline solution to be sheared and broken into small droplets. This further allows the alkaline solution to be fully mixed in the nitrobenzene liquid and neutralized with the acid during the swirling flow. Therefore, the nitrobenzene liquid alkaline washing method of the present invention can fully mix the nitrobenzene liquid and the alkaline solution, thereby enabling the acid solution in the nitrobenzene liquid to come into effective contact with the alkaline solution, thus reducing the amount of alkaline solution used and reducing alkali consumption.

[0058] In some embodiments of the present invention, the nitrobenzene liquid alkaline washing method can be carried out using the static mixer described in the above embodiments.

[0059] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, and the existence of an infinite number of specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the concept and technical solution of the present invention to other occasions without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A static mixer, characterized in that, include: The outer casing (1) has a mixing chamber (11) inside. The first end of the outer casing (1) has a first liquid inlet (12) for the raw material liquid to enter the mixing chamber (11), and the last end of the outer casing (1) has a mixing outlet (13) for the mixed liquid to flow out of the mixing chamber (11). A delivery pipe (2) extends from the first end of the outer casing (1) through the mixing chamber (11) to the end of the outer casing (1). The first port of the delivery pipe (2) at the first end extends out of the outer casing (1) and forms a second liquid inlet (22). The second port of the delivery pipe (2) at the end is closed. The portion of the delivery pipe (2) located in the mixing chamber (11) forms a spray section (21). The pipe wall of the spray section (21) is provided with a plurality of spray holes (23) spaced apart for spraying the cleaning liquid input through the second liquid inlet (22) into the mixing chamber (11). The outer periphery of the spray section (21) is provided with a first helical blade (24) and a second helical blade (25) spaced apart along its axial direction. The helical directions of the first helical blade (24) and the second helical blade (25) are opposite.

2. The static mixer according to claim 1, characterized in that, The mixing chamber (11) includes a first variable diameter region (14), a buffer zone (15), and a second variable diameter region (16) distributed sequentially along the direction from the first liquid inlet (12) to the mixed liquid outlet (13), and the first helical blade (24) and the second helical blade (25) are located in the first variable diameter region (14) and the second variable diameter region (16), respectively. And / or, the outer casing (1) is cylindrical, the axial direction of the first liquid inlet (12) is perpendicular to the axial direction of the outer casing (1), and the axial direction of the mixture outlet (13) is the same as the axial direction of the outer casing (1).

3. The static mixer according to claim 2, characterized in that, The first variable diameter zone (14) includes a first mixing section (141), a first expansion section (142) and a first contraction section (143) distributed sequentially along the axial direction of the injection section (21). The first mixing section (141) is connected to the first liquid inlet (12), and the first contraction section (143) is connected to the buffer zone (15). The diameter of the first tapering section (143) gradually decreases along the direction from the first liquid inlet (12) to the mixture outlet (13). The minimum diameter of the first tapering section (143) is the same as the diameter of the buffer zone (15). The maximum diameter of the first tapering section (143) is the same as the diameter of the first expansion section (142). The diameter of the first expansion section (142) is greater than the diameter of the first mixing section (141).

4. The static mixer according to claim 3, characterized in that, The wall of the first mixing section (141) has a first radial distance between it and the outer edge of the first spiral blade (24). The minimum radial distance between the wall of the first tapering section (143) and the outer edge of the first spiral blade (24) is a second radial distance. The outer wall of the spray section (21) has a third radial distance between it and the wall of the first mixing section (141). The first radial distance and the second radial distance are 1 / 8 to 1 / 4 of the third radial distance.

5. The static mixer according to claim 3, characterized in that, The wall surface of the first expansion section (142) is provided with a first spiral line-shaped ridge (144) surrounding the first spiral blade (24), and the spiral direction of the first spiral line-shaped ridge (144) is opposite to the spiral direction of the first spiral blade (24).

6. The static mixer according to claim 3, characterized in that, The axial length of the buffer zone (15) is less than or equal to the axial length of the first mixing section (141).

7. The static mixer according to claim 4, characterized in that, The axial length of the second variable diameter region (16) is less than the axial length of the first variable diameter region (14); The second variable diameter zone (16) includes a second mixing section (161), a second expansion section (162) and a second tapering section (163) distributed sequentially along the axial direction of the injection section (21). The second mixing section (161) is connected to the buffer zone (15), and the second tapering section (163) is connected to the mixture outlet (13). The diameter of the second tapering section (163) gradually decreases along the direction from the second liquid inlet (22) to the mixture outlet (13). The minimum diameter of the second tapering section (163) is the same as the diameter of the mixture outlet (13). The maximum diameter of the second tapering section (163) is the same as the diameter of the second expansion section (162). The diameter of the second expansion section (162) is greater than the diameter of the second mixing section (161). The diameter of the second mixing section (161) is equal to the diameter of the buffer zone (15).

8. The static mixer according to claim 7, characterized in that, The wall of the second mixing section (161) has a fourth radial distance between it and the outer edge of the second helical blade (25). The minimum radial distance between the wall of the second tapering section (163) and the outer edge of the second helical blade (25) is a fifth radial distance. The outer wall of the spray section (21) has a sixth radial distance between it and the wall of the second mixing section (161). The fourth radial distance and the fifth radial distance are 1 / 8 to 1 / 4 of the sixth radial distance.

9. The static mixer according to claim 7, characterized in that, The second expansion section (162) has a second spiral-shaped ridge (164) surrounding the second spiral blade (25) on its wall surface. The spiral direction of the second spiral-shaped ridge (164) is opposite to the spiral direction of the second spiral blade (25).

10. The static mixer according to claim 7, characterized in that, All the injection holes (23) are distributed in multiple rows and columns on the injection section (21), and the number of injection holes (23) located in the first diameter change zone (14) is greater than the number of injection holes (23) located in the second diameter change zone (16); In the axial direction of the injection section (21), the distance between two adjacent injection holes (23) in the buffer zone (15) is smaller than the distance between two adjacent injection holes (23) in the second variable diameter zone (16).

11. The static mixer according to claim 10, characterized in that, The diameter of the injection hole (23) gradually decreases from its inlet end to its outlet end. The hole wall of the injection hole (23) is provided with a third spiral-shaped ridge (26) distributed around the axis of the injection hole (23). The injection hole (23) extends obliquely towards the head end of the outer shell (1) from its inlet end to its outlet end.

12. A liquid alkaline washing method for nitrobenzene, characterized in that, include: The nitrobenzene liquid containing acid is guided to flow forward spirally along a first spiral trajectory, and then the nitrobenzene liquid is guided to flow forward spirally along a second spiral trajectory, with the spiral direction of the first spiral trajectory being opposite to that of the second spiral trajectory; at the same time, an alkaline solution is sprayed into the forward-flowing nitrobenzene liquid.

13. The liquid alkaline washing method for nitrobenzene according to claim 12, characterized in that, The nitrobenzene liquid alkaline washing method is carried out using the static mixer described in any one of claims 1-11.

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