Mixed reactor for the acetonitrile amidation

Abstract

This utility model relates to the field of acetone cyanohydrin amidation technology, specifically to a mixing reactor for acetone cyanohydrin amidation. The mixing reactor has a horizontal structure, with a mixture inlet, a reactant outlet, and at least one acetone cyanohydrin inlet on the shell. An inner tube connecting the mixture inlet is provided inside the shell, and at least one nozzle is provided on the inner tube. The acetone cyanohydrin inlet is an inner-extended structure and corresponds to the nozzle. The inner tube consists of a vertical section and a horizontal section, with the vertical section located at the end or midpoint of the horizontal section. This mixing reactor maximizes the uniform mixing of materials, improving the utilization rate of the reactor and the raw materials.

Description

Technical Field

[0001] This utility model relates to the field of acetone cyanohydrin amidation technology, specifically to a mixed reactor for acetone cyanohydrin amidation. Background Technology

[0002] Methyl methacrylate (MMA) is a major raw material for the production of acrylic sheets, PMMA molding compounds, and high-grade coatings. It is widely used in military, optical fiber, sanitary ware, high-grade adhesives, high-grade paints, PVC modifier ACR, aquariums, outdoor billboards, and display light guide materials, among other fields.

[0003] There are many production processes for methyl methacrylate (MMA), among which the acetone cyanohydrin method is the earliest industrialized method for producing MMA. Due to its mature technology and the ability to utilize acrylonitrile to produce hydrogen cyanide as a byproduct, the acetone cyanohydrin method currently accounts for about 80% of the world's total MMA production.

[0004] In the acetone cyanohydrin process for producing methyl methacrylate (MMA), the intermediate reaction of acetone cyanohydrin reacting with concentrated sulfuric acid to form α-formamidoisopropyl hydrogen sulfate (SIBA) is a key step in MMA production. The reaction formula is as follows:

[0005]

[0006] This reaction is highly exothermic, has a high system viscosity, and a fast reaction rate. If the heat of reaction is not removed in time, overheating will occur, leading to the decomposition of the raw material ACH and the generation of numerous side reactions. This not only reduces the yield but also causes some byproducts to further react in downstream processes, leading to blockages and preventing the equipment from operating normally. Furthermore, due to the high system viscosity, mass transfer is difficult, resulting in low mixing uniformity and low raw material utilization. External auxiliary equipment (such as a stirrer) is required for homogenization, and excessive concentrated sulfuric acid is added to dilute the system. This is one of the main reasons limiting the product yield and significantly increasing the production cost and energy consumption of this process.

[0007] CN116726843A discloses an acetone cyanohydrin amidation reactor and its control system. This amidation reactor uses a specially designed stirrer and acetone cyanohydrin distributor to achieve rapid and uniform mixing of acetone cyanohydrin and sulfuric acid. However, the reaction system has high viscosity and strong material adhesion, easily adhering to the surface of the stirring blades and rotating shaft. This leads to a series of problems such as reduced stirring effect, increased energy consumption, and the need for regular cleaning. Furthermore, stirring the high-viscosity system generates a certain amount of stirring heat, which is not conducive to heat dissipation and increases energy consumption. The presence of the stirrer also reduces the effective volume of the reactor to some extent, increasing equipment investment and operating costs.

[0008] Therefore, it is necessary to develop an amidation apparatus that can reduce the occurrence rate of side reactions in the amidation of acetone cyanohydrin and improve the reaction yield. Summary of the Invention

[0009] The purpose of this invention is to overcome the problems of existing acetone cyanohydrin amidation reactions, such as high exothermic reaction rate, slow heat removal, thermal decomposition of raw materials, side reactions, high viscosity of the reaction system, impaired mass transfer, low raw material utilization, and low product yield, and to provide a mixed reactor for acetone cyanohydrin amidation.

[0010] To achieve the above objectives, this utility model provides a mixing reactor for the amidation of acetone cyanohydrin. The mixing reactor has a horizontal structure, with a mixture inlet, a reactant outlet, and at least one acetone cyanohydrin inlet on the shell. An inner extension pipe connected to the mixture inlet is provided inside the shell, and at least one nozzle is provided on the inner extension pipe.

[0011] The acetone cyanohydrin inlet has an internal structure and corresponds to the nozzle.

[0012] The inner tube is composed of a vertical section and a horizontal section, with the vertical section located at the end point or midpoint of the horizontal section.

[0013] Compared with the prior art, this utility model has the following advantages:

[0014] (1) The mixing reactor provided by this utility model includes an inner tube with a nozzle and an acetone cyanohydrin inlet. It has good mass transfer and mixing, and low investment and energy consumption. The inner tube with the nozzle directly sprays and disperses the mixed materials, which significantly increases the mass transfer and radiation area of ​​the feed, so that it is distributed in the mixing reactor in a larger cross-sectional area. It is fed in conjunction with the inner acetone cyanohydrin inlet above the nozzle. No additional agitator is needed, which can avoid the occurrence of fluid mixing dead zone, maximize the uniform mixing of materials in the reactor, and improve the utilization rate of the reactor and raw materials.

[0015] (2) The mixing reactor provided by this utility model adopts a horizontal structure. A cooler is installed on the pipe connecting the outlet of the reactant material and the inlet of the mixture material. An external tracing pipe and a removable U-shaped heat exchanger are used as heat removal means, which effectively increases the heat exchange contact area, meets the heat exchange requirements of the amidation system, and takes into account the characteristics of low cost and easy maintenance. It is more suitable for the continuous flow and easily scaled and corroded acetone cyanohydrin production MMA reaction system.

[0016] (3) The mixing reactor provided by this utility model is used for acetone cyanohydrin amidation. Through sufficient mass transfer and timely heat exchange, the utilization rate of raw materials and the selectivity of products are effectively improved. That is, by reducing the thermal decomposition of raw material acetone cyanohydrin, high selectivity of α-formamide isopropyl hydrogen sulfate is obtained. Attached Figure Description

[0017] Figure 1This is a longitudinal cross-sectional view of the mixing reactor for acetone cyanohydrin amidation provided by this utility model;

[0018] Figure 2 This is a longitudinal cross-sectional view of a specific mixing reactor for the amidation of acetone cyanohydrin provided by this utility model;

[0019] Figures 3a-3b This is a schematic diagram of the specific structure of the inner tube provided by this utility model;

[0020] Figure 4 This is a longitudinal cross-sectional view of an inner extension tube provided by this utility model;

[0021] Figure 5 This is a schematic diagram of the reactor structure for the amidation of acetone cyanohydrin provided in Comparative Example 3.

[0022] Explanation of reference numerals in the attached figures

[0023] 1. Shell; 201. External tracing pipe; 202. Heat exchange medium inlet; 203. Heat exchange medium outlet; 204. Outer jacket; 301. Inner extension pipe; 302. Nozzle; 303. Mixture inlet; 4. Removable U-shaped heat exchanger; 5. Acetone cyanohydrin inlet; 6. Reactant outlet; 7. Mixture reflux port; 8. Safety valve port; 9. Gas phase balance port; 10. Spare port; 11. Manhole;

[0024] 1201-1204, sight glass; 1301a-1303a, upper port of level gauge; 1301b-1303b, lower port of level gauge; 1401-1403, thermometer; 1501-1502, saddle. Detailed Implementation

[0025] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0026] In this invention, unless otherwise specified, "first" and "second" do not indicate a sequence or limit the specific materials or steps; they are merely used to distinguish or indicate that these are not the same material or step. For example, "first" and "second" in "first heat exchange medium" and "second heat exchange medium" are only used to indicate that these are not the same heat exchange medium.

[0027] In this utility model, unless otherwise specified, the top of the container refers to the 0-10% position of the container from top to bottom, the upper part of the container refers to the 10-40% position of the container from top to bottom, the middle part of the container refers to the 40-60% position of the container from top to bottom, the lower part of the container refers to the 60-90% position of the container from top to bottom, and the bottom of the container refers to the 90-100% position of the container from top to bottom.

[0028] This invention provides a mixing reactor for the amidation of acetone cyanohydrin, the longitudinal cross-sectional view of which is shown below. Figure 1-2 As shown, the mixing reactor has a horizontal structure. The shell 1 is provided with a mixture inlet 303, a reactant outlet 6 and at least one acetone cyanohydrin inlet 5. The shell 1 is provided with an inner extension pipe 301 connected to the mixture inlet 303, and at least one nozzle 302 is provided on the inner extension pipe 301.

[0029] The acetone cyanohydrin inlet 5 is an internally extended structure and corresponds to the nozzle 302.

[0030] The inner tube 301 is composed of a vertical section and a horizontal section, with the vertical section located at the end point or midpoint of the horizontal section.

[0031] Compared with the prior art, the inventors of this utility model have discovered for the first time that by using the inner extension pipe 301, the nozzle 302 and the built-in acetone cyanohydrin inlet 5 in the shell 1 of the mixing reactor as homogenization methods, the equipment investment and operating costs are effectively reduced, the effective internal volume of the reactor is increased, and the characteristics of good mass transfer and high utilization rate are taken into account. It is more suitable for the acetone cyanohydrin to MMA production reaction system with high viscosity and easy polymerization and adhesion.

[0032] In this utility model, preferably, as follows: Figure 1-2 As shown, the ratio of the inner diameter D to the length of the housing 1 is 0.2-0.8:1, for example, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, and any value within the range of any two values, preferably 0.4-0.7:1.

[0033] In this utility model, preferably, as follows: Figure 1-2 As shown, the inner diameter D of the housing 1 is 1000-3500mm, for example, 1000mm, 1500mm, 2000mm, 2500mm, 3000mm, 3500mm, and any value within the range of any two values, preferably 1500-3000mm.

[0034] In this utility model, preferably, as follows: Figure 1-2As shown, the top of the shell 1 is provided with the mixture inlet 303 and the acetone cyanohydrin inlet 5; the bottom of the shell 1 is provided with the reactant outlet 6. More preferably, the reactant outlet 6 is located at the middle position of the bottom of the shell 1.

[0035] In this invention, the mixing material inlet 303 is connected to an inner extension pipe 301, and at least one nozzle 302 is provided on the inner extension pipe 301. In this invention, the shape of the inner extension pipe 301 is not limited, such as… Figures 3a-3b As shown, the inner tube 301 consists of a vertical section and a horizontal section. The vertical section can be located at the end point of the horizontal section or at the midpoint of the horizontal section.

[0036] In this utility model, preferably, as follows: Figures 3a-3b As shown, the vertical section of the inner extension pipe is connected to the mixture inlet 303, and the nozzle 302 is provided on the horizontal section of the inner extension pipe.

[0037] In this utility model, preferably, as follows: Figure 1 As shown, the ratio of the vertical distance H1 from the horizontal section of the inner tube to the bottom of the housing 1 to the inner diameter D of the housing 1 is 0.3-0.35:1, for example, 0.3:1, 0.32:1, 0.35:1, and any value within the range of any two values.

[0038] In this invention, the inner tube serves as a homogenization method in the mixing reactor. Its position has a significant impact on the mass transfer of the system materials, including the degree of mixing and the extent of the reactor dead zone. Appropriate positioning can improve the utilization rate of the reactor and raw materials.

[0039] In this utility model, preferably, as follows: Figure 4 As shown, the angle α between the nozzle 302 and the center line of the horizontal section is 10°-90°, for example, 10°, 30°, 45°, 60°, 90°, or any value within the range of any two values, preferably 30°-60°; the angle β between the nozzle 302 and the center line of the vertical section is 10°-90°, for example, 10°, 30°, 45°, 60°, 90°, or any value within the range of any two values, preferably 30°-60°. In this utility model, unless otherwise specified, the extended structure refers to the acetone cyanohydrin inlet 5 extending into the housing 1.

[0040] In this utility model, preferably, as follows: Figure 1-2 As shown, the shortest vertical distance from the propanol cyanohydrin inlet 5 to the horizontal section of the inner tube is 350-1000 mm.

[0041] In this invention, preferably, the number of nozzles 302 and acetone cyanohydrin inlets 5 are each 1-10, more preferably 2-4.

[0042] In this utility model, more preferably, such as Figure 1-2 As shown, on the inner tube 301, two adjacent nozzles 302 are arranged in an alternating pattern at equal intervals.

[0043] In this utility model, preferably, as follows: Figure 1-2 As shown, a removable U-shaped heat exchanger 4 is provided inside the shell 1, located below the inner extension tube 301. That is, a removable U-shaped heat exchanger 4 is inserted between the horizontal section of the inner extension tube and the bottom of the shell 1 to remove heat from the reaction system. The shortest vertical distance H2 from the removable U-shaped heat exchanger 4 to the bottom of the shell is...

[0044] In this utility model, preferably, as follows: Figure 1 As shown, the ratio of the shortest vertical distance H2 from the removable U-shaped heat exchanger 4 to the bottom of the shell 1 to the vertical distance H1 from the horizontal section of the inner tube to the bottom of the shell 1 is 0.2-0.3:1, for example, 0.2:1, 0.22:1, 0.25:1, 0.28:1, 0.3:1, or any value within any range of two such values. By adjusting the above ratio range, the heat released by the acetone cyanohydrin amidation reaction can be exchanged in a timely manner, the temperature inside the shell can be controlled, and by suppressing byproducts such as the decomposition of acetone cyanohydrin, the raw material utilization rate and product selectivity of acetone cyanohydrin can be improved.

[0045] In this utility model, preferably, the removable U-shaped heat exchanger 4 is composed of a heat exchanger shell and at least one heat exchange tube; more preferably, the outer diameter of the heat exchange tube is 19-32mm, for example, 19mm, 22mm, 25mm, 28mm, 30mm, 32mm, and any value within the range of any two values.

[0046] In this invention, to further optimize the heat exchange effect, preferably, the center-to-center distance between two adjacent heat exchange tubes is 25-40 mm, for example, 25 mm, 30 mm, 33 mm, 35 mm, 38 mm, 40 mm, or any value within the range of any two values.

[0047] The internal extension length of the retractable U-shaped heat exchange tube in this invention is based on the following considerations: to maximize the heat exchange area while avoiding interference with other internal components and the inner wall of the reactor, and while reserving necessary space for manufacturing, installation, and expansion. Furthermore, the expansion along the length of the heat exchange tube caused by reactor temperature rise is minimal, approximately 10 mm.

[0048] In this invention, preferably, a cooler is provided on the pipe connecting the reactant outlet 6 and the mixture inlet 303 according to the material flow direction, so that some of the amidation reactants are cooled and then flowed back into the shell through the mixture inlet 303. By regulating the temperature inside the shell, the degree of reaction and product selectivity are improved.

[0049] In this utility model, such as Figure 2 As shown, preferably, an external tracing pipe 201 is wound around the shell 1; more preferably, the shell 1 is also provided with a heat exchange medium inlet 202 and a heat exchange medium outlet 203 that connect the external tracing pipe 201.

[0050] In this utility model, preferably, in the external heat exchanger 201, the mass flow rate of the first heat exchange medium is 1-3 m / s, and the temperature of the first heat exchange medium is 50-70℃.

[0051] In this utility model, preferably, in the extractable U-shaped heat exchanger 4, the mass flow rate of the second heat exchange medium is 1-3 m / s, and the temperature of the second heat exchange medium is 50-70℃.

[0052] The mixing reactor provided by this utility model is also equipped with an external heat exchanger 201 and a removable U-shaped heat exchanger 4, which features high heat exchange efficiency and easy disassembly and maintenance. The high flow velocity of the first heat exchange medium in the external heat exchanger 201 ensures thorough and uniform heat exchange, while also being non-pressure vessel, reducing equipment costs. Simultaneously used with the removable U-shaped heat exchanger 4 as the heat transfer method in the mixing reactor, it achieves excellent heat exchange effects and facilitates equipment cleaning and replacement. The further improved horizontal reactor design removes the heat exchange limit of vertical reactors, providing a larger heat exchange area for the mixing reactor.

[0053] In this invention, the first heat exchange medium flows in and out of the external tracing pipe 201 through the heat exchange medium inlet 202 and the heat exchange medium outlet 203, which can achieve excellent heat exchange effect and meet the heat exchange requirements of the amidation system.

[0054] In this utility model, preferably, as follows: Figure 1-2 As shown, the shell 1 is also provided with at least one mixture return port 7. In this invention, when multiple mixing reactors are used in series, the mixture return port 7 is used for cascade reflux of the reaction outputs from each stage.

[0055] In this utility model, preferably, as follows: Figure 1 As shown, the housing 1 is also provided with a safety valve port 8, a gas phase balance port 9, and a spare port 10. In this utility model, the safety valve port 8 is used to install a safety valve, the gas phase balance port 9 is used to discharge the gas phase components inside the housing, and the spare port 10 is a spare connection port to cope with different working conditions.

[0056] In this utility model, preferably, as follows: Figure 2 As shown, the housing 1 is also provided with a liquid level gauge upper port 1301a-1303a, a liquid level gauge lower port 1301b-1303b and a thermometer 1401-1403, which are used to install the liquid level gauge and the thermometer to monitor and control the reaction temperature and other states of the reaction system.

[0057] In this utility model, preferably, as follows: Figure 2 As shown, the housing 1 is also provided with a manhole 11 and sight glasses 1201-1204 to facilitate observation of the interior of the housing and the condition of each inner extension pipe.

[0058] In this utility model, preferably, as follows: Figure 2 As shown, the bottom of the shell 1 is also provided with saddles 1501-1502, wherein saddle 1501 is a fixed end and saddle 1502 is a movable end to support the reactor.

[0059] In this utility model, such as Figure 1-2 As shown, the mixture enters the inner tube 301 through the mixture inlet 303, and is then evenly sprayed into the shell 1 through the nozzle 302; the acetone cyanohydrin inlet 5 extends into the shell, allowing the acetone cyanohydrin to directly mix and react with the mixture sprayed from the nozzle 302. After the raw materials are fully mixed and reacted, the reactants are discharged through the reactant outlet 6 and mixed with supplementary sulfuric acid, then split into two streams. Part of the mixture flows back into the reactor through the mixture inlet 303, and the remaining part flows into the next process as a reaction discharge.

[0060] In this invention, unless otherwise specified, the reaction product undergoes a next-stage amidation reaction, causing α-formamidoisopropyl hydrogen sulfate in the reaction product to be converted into methacrylamide sulfate under the action of sulfuric acid.

[0061] According to a particularly preferred embodiment of the present invention, a mixing reactor for acetone cyanohydrin amidation is provided. The mixing reactor has a horizontal structure, and the shell is provided with a mixture inlet, a reactant outlet and at least one acetone cyanohydrin inlet. An inner tube is provided inside the shell, and a removable U-shaped heat exchanger is located below the inner tube. An outer tracing pipe is wound around the shell.

[0062] The inner tube consists of a vertical section and a horizontal section, with the vertical section located at the end or midpoint of the horizontal section; the vertical section connects to the mixing material inlet, and at least one nozzle is provided on the horizontal section; the acetone cyanohydrin inlet is an inner tube structure and corresponds to the nozzle.

[0063] Wherein, the ratio of the vertical distance H1 from the horizontal section of the inner tube to the bottom of the shell to the inner diameter D of the shell is 0.3-0.35:1;

[0064] Wherein, the angle α between the nozzle and the center line of the horizontal section is 10°-90°, preferably 30°-60°; the angle β between the nozzle and the center line of the vertical section is 10°-90°, preferably 30°-60°.

[0065] The present invention will be described in detail below through embodiments.

[0066] The selectivity of α-formamidoisopropyl hydrogen sulfate is calculated using the following formula:

[0067]

[0068] S SIBA选择性 Selectivity of α-formamidoisopropyl hydrogen sulfate, %

[0069] W SIBA The mass content (wt%) of α-formamidoisopropyl hydrogen sulfate in the reaction product.

[0070] W MAAS The mass content of methacrylamide sulfate in the reaction product, in wt%

[0071] M: Relative molecular mass of α-formamidoisopropyl hydrogen sulfate and methacrylamide sulfate, 183.183 g / mol;

[0072] m S3 : The mass of reactant discharged per unit time, in grams;

[0073] n ACH : The amount of acetone cyanohydrin added per unit time, in mol.

[0074] Example 1

[0075] like Figure 1-2 As shown, the mixing reactor has a horizontal structure. The shell 1 is provided with a mixture inlet 303, a reactant outlet 6, and four acetone cyanohydrin inlets 5. The shell 1 is provided with an external tracing pipe 201, a heat exchange medium inlet 202, and a heat exchange medium outlet 203. Inside the shell 1, there is an inner extension pipe 301 composed of vertical and horizontal pipes. The vertical pipe is connected to the mixture inlet 303, and the horizontal pipe is provided with four nozzles corresponding to the acetone cyanohydrin inlets 5. The shell 1 is also provided with a removable U-shaped heat exchanger 4 located below the inner extension pipe 301.

[0076] The inner diameter D of the shell 1 is 2500mm and the length is 3600mm; the vertical distance H1 from the horizontal section of the inner extension pipe to the bottom of the shell 1 is 800mm; two adjacent nozzles 302 are arranged equidistantly and alternately, and the angles α and β between the nozzle 302 and the horizontal and vertical sections of the inner extension pipe are both 45°; the acetone cyanohydrin inlet 5 is an inner extension structure, and its shortest vertical distance to the horizontal section of the inner extension pipe is 600mm.

[0077] The shortest vertical distance H2 from the removable U-shaped heat exchanger 4 to the bottom of the shell 1 is 200mm. The removable U-shaped heat exchanger 4 consists of a heat exchanger shell and 34 heat exchange tubes. The outer diameter of the heat exchange tubes is 25mm and the center-to-center distance between adjacent heat exchange tubes is 33mm.

[0078] The method is carried out in the above-mentioned mixing reactor and includes:

[0079] The mixture M1 and acetone cyanohydrin (116.5 mol / h) were brought into contact and reacted at 95°C for 1.2 h. The reactants were then mixed with 100.2 wt% added sulfuric acid to obtain the mixture stream, which was divided into the above mixture M1 and the reaction output S1.

[0080] The molar ratio of supplemented sulfuric acid to acetone cyanohydrin is 1.55:1.

[0081] The above mixture stream of 96 vol% is cooled to 95°C and then reused as the above mixture material M1. The reaction output S1 flows to the next process at a flow rate of 27680 kg / h.

[0082] In the aforementioned external heat exchanger, the flow velocity of the first heat exchange medium is 2.5 m / s and the temperature is 60°C; in the aforementioned extractable U-shaped heat exchanger, the flow velocity of the second heat exchange medium is 2.5 m / s and the temperature is 60°C.

[0083] In the above-mentioned reaction output S1, the content of α-formamidoisopropyl hydrogen sulfate is 49.71 wt%, the content of sulfuric acid is 19.21 wt%, and the content of methacrylamide sulfate is 25.52 wt%.

[0084] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product S1 is 97.87%.

[0085] Example 2

[0086] The mixing reactor provided in Example 1 differs in that...

[0087] Adjust the vertical distance H1 from the horizontal section of the inner tube to the bottom of the housing 1 to 950mm;

[0088] The method provided in Embodiment 1 differs from the method described above in that it is performed within the aforementioned apparatus.

[0089] Under the same conditions, the reaction output S2 with a flow rate of 27622 kg / h was obtained.

[0090] In the above-mentioned reaction output S2, the content of α-formamidoisopropyl hydrogen sulfate is 49.48 wt%, the content of sulfuric acid is 19.60 wt%, and the content of methacrylamide sulfate is 25.40 wt%.

[0091] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product S2 is 96.91%.

[0092] Example 3

[0093] The mixing reactor provided in Example 1 differs in that...

[0094] Adjust the angles α and β between the nozzle 302 and the horizontal and vertical sections of the inner extension pipe to 90°.

[0095] The method provided in Embodiment 1 differs from the method described above in that it is performed within the aforementioned apparatus.

[0096] Under the same conditions, the reaction output S3 with a flow rate of 27165 kg / h was obtained.

[0097] Among them, the above-mentioned reaction output S3 contains 48.71 wt% α-formamidoisopropyl hydrogen sulfate, 20.80 wt% sulfuric acid, and 25.01 wt% methacrylamide sulfate.

[0098] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product S3 is 93.84%.

[0099] Example 4

[0100] The mixing reactor provided in Example 1 differs in that...

[0101] Adjust the shortest vertical distance from the propanol cyanohydrin inlet 5 to the horizontal section of the inner extension pipe to 1100 mm;

[0102] The method provided in Embodiment 1 differs from the method described above in that it is performed within the aforementioned apparatus.

[0103] Under the same conditions, the reaction output S4 with a flow rate of 27534 kg / h was obtained.

[0104] Among them, the above-mentioned reaction output S4 contains 49.22 wt% α-formamidoisopropyl hydrogen sulfate, 19.94 wt% sulfuric acid, and 25.27 wt% methacrylamide sulfate.

[0105] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product S4 is 96.10%.

[0106] Example 5

[0107] The mixing reactor provided in Example 1;

[0108] The method provided in Example 1 is different,

[0109] The flow rate of the first heat exchange medium is set to 1 m / s and the temperature to 50℃.

[0110] The flow rate of the second heat exchange medium is adjusted to 1 m / s and the temperature to 50℃;

[0111] Under the same conditions, the reaction output S5 was obtained with a flow rate of 27499 kg / h;

[0112] Among them, the above-mentioned reaction output S5 contains 49.09 wt% α-formamidoisopropyl hydrogen sulfate, 20.23 wt% sulfuric acid, and 25.20 wt% methacrylamide sulfate.

[0113] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product S5 is 95.74%.

[0114] Example 6

[0115] The mixing reactor provided in Example 1;

[0116] The method provided in Example 1 is different,

[0117] The temperature of the above reaction was adjusted to 115℃;

[0118] Under the same conditions, the reaction output S6 with a flow rate of 26650 kg / h was obtained;

[0119] Among them, the above-mentioned reaction output S6 contains 40.22 wt% α-formamidoisopropyl hydrogen sulfate, 24.84 wt% sulfuric acid, and 29.73 wt% methacrylamide sulfate.

[0120] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product S6 is 87.36%.

[0121] Example 7

[0122] The mixing reactor provided in Example 1;

[0123] The method provided in Example 1 is different,

[0124] The concentration of the supplemented sulfuric acid was adjusted to 99 wt%.

[0125] Under the same conditions, the reaction output S7 with a flow rate of 27483 kg / h was obtained;

[0126] Among them, the above-mentioned reaction output S7 contains 49.03 wt% α-formamidoisopropyl hydrogen sulfate, 20.29 wt% sulfuric acid, and 25.17 wt% methacrylamide sulfate.

[0127] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product S7 is 95.55%.

[0128] Example 8

[0129] The mixing reactor provided in Example 1;

[0130] The method provided in Example 1 is different,

[0131] The flow rate of acetone cyanohydrin was 582.5 mol / h;

[0132] The above mixture stream of 80 vol% was cooled to 95°C and then used as the above mixture material M1;

[0133] Under the same conditions, the reaction output S8 was obtained with a flow rate of 1339455 kg / h;

[0134] Among them, the above-mentioned reaction output S8 contains 46.71 wt% α-formamidoisopropyl hydrogen sulfate, 24.32 wt% sulfuric acid, and 23.98 wt% methacrylamide sulfate.

[0135] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product S8 is 88.74%.

[0136] Comparative Example 1

[0137] The mixing reactor provided in Example 1 differs in that...

[0138] The housing 1 does not contain an inner extension tube 301 or a nozzle 302;

[0139] The method provided in Example 1 is different in that it is carried out in the above-described mixing reactor.

[0140] Under the same conditions, the reaction output DS1 with a flow rate of 26640 kg / h was obtained.

[0141] Of the above-mentioned reaction effluent DS1, the content of α-formamidoisopropyl hydrogen sulfate was 46.17 wt%, the content of sulfuric acid was 24.55 wt%, and the content of methacrylamide sulfate was 23.70 wt%.

[0142] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product DS1 is 87.22%.

[0143] Comparative Example 2

[0144] The mixing reactor provided in Example 1 differs in that...

[0145] The acetone cyanohydrin inlet 5 is located on the shell 1, that is, it does not have an internal extension structure;

[0146] The method provided in Example 1 is different in that it is carried out in the above-described mixing reactor.

[0147] Under the same conditions, the reaction output DS2 with a flow rate of 26636 kg / h was obtained.

[0148] Of the above-mentioned reaction effluent DS2, the content of α-formamidoisopropyl hydrogen sulfate was 46.15 wt%, the content of sulfuric acid was 24.86 wt%, and the content of methacrylamide sulfate was 23.69 wt%.

[0149] Analysis and calculation show that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product DS2 is 87.17%.

[0150] Comparative Example 3

[0151] Mixing reactors such as Figure 5 As shown, it is a vertical structure. The shell 1 is provided with a mixture inlet 303, a reactant outlet 6, a gas phase balance port 9, and a liquid level gauge port 1301a; the shell 1 is provided with an outer jacket 204, a heat exchange medium inlet 202, and a heat exchange medium outlet 203.

[0152] The inner diameter D of the shell 1 is 2400mm and the height is 3500mm; the inner extension length of the mixture inlet 303 is 1900mm.

[0153] The method is carried out in the above-mentioned mixing reactor and includes:

[0154] 100.2 wt% sulfuric acid and acetone cyanohydrin (116.5 mol / h) were mixed at a molar ratio of 1.55:1 and added to the reactor through the mixture inlet 303 for reaction at 95°C for 1.2 h, resulting in two streams of reactants.

[0155] Of these, 96 vol% of the above material is cooled to 95°C and reused, while the remaining portion is used as reaction effluent DS3 and flows to the next process at a flow rate of 26,655 kg / h.

[0156] In the aforementioned outer jacket 204, the flow rate of the heat exchange medium is 1 m / s and the temperature is 60 °C.

[0157] Of the above-mentioned reaction effluent DS3, the content of α-formamidoisopropyl hydrogen sulfate was 46.21 wt%, the content of sulfuric acid was 25.02 wt%, and the content of methacrylamide sulfate was 23.72 wt%.

[0158] Analysis and calculation showed that the selectivity of α-formamidoisopropyl hydrogen sulfate in the above reaction product DS3 was 87.34%.

[0159] Compared with Comparative Examples 1-3, Examples 1-8 use the mixed reactor provided by this invention for acetone cyanohydrin amidation, which has higher raw material utilization and product selectivity, that is, higher selectivity for α-formamidoisopropyl hydrogen sulfate.

[0160] The preferred embodiments of this utility model have been described in detail above; however, this utility model is not limited thereto. Within the scope of the technical concept of this utility model, various simple modifications can be made to the technical solution of this utility model, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed by this utility model and are all within the protection scope of this utility model.

Claims

1. A mixed reactor for acetonitrile amidation, characterized by, The mixing reactor is a horizontal structure, with a mixture inlet (303), a reactant outlet (6) and at least one acetone cyanohydrin inlet (5) provided on the shell (1); an inner tube (301) connected to the mixture inlet (303) is provided inside the shell (1), and at least one nozzle (302) is provided on the inner tube (301). The acetone cyanohydrin inlet (5) is an internally extended structure and corresponds to the nozzle (302); The inner tube (301) is composed of a vertical section and a horizontal section, with the vertical section located at the end point or midpoint of the horizontal section.

2. The hybrid reactor of claim 1, wherein, The ratio of the inner diameter D to the length of the shell (1) is 0.2-0.8:1; The inner diameter D of the shell (1) is 1000-4000mm.

3. The mixing reactor according to claim 2, characterized in that, The ratio of the inner diameter D to the length of the shell (1) is 0.4-0.7:1; The inner diameter D of the shell (1) is 1500-3000mm.

4. The mixing reactor according to claim 1, characterized in that, The vertical section of the inner extension pipe is connected to the mixture inlet (303), and the nozzle (302) is provided on the horizontal section of the inner extension pipe. The ratio of the vertical distance H1 from the horizontal section of the inner tube to the bottom of the housing (1) to the inner diameter D of the housing (1) is 0.3-0.35:

1.

5. The mixing reactor according to claim 1, characterized in that, The angle α between the nozzle (302) and the center line of the horizontal section is 10°-90°; The angle β between the nozzle (302) and the center line of the vertical section is 10°-90°.

6. The mixing reactor according to claim 5, characterized in that, The angle α between the nozzle (302) and the center line of the horizontal section is 30°-60°; The angle β between the nozzle (302) and the center line of the vertical section is 30°-60°.

7. The mixing reactor according to claim 1, characterized in that, The shortest vertical distance from the acetone cyanohydrin inlet (5) to the horizontal section of the inner tube is 350-1000 mm; The number of each nozzle (302) and acetone cyanohydrin inlet (5) is independently 1-10; On the inner tube (301), two adjacent nozzles (302) are arranged in an alternating pattern at equal intervals.

8. The mixing reactor according to claim 1, characterized in that, The shell (1) is provided with a removable U-shaped heat exchanger (4) located below the inner tube (301). The removable U-shaped heat exchanger (4) consists of a heat exchanger shell and at least one heat exchange tube.

9. The mixing reactor according to claim 8, characterized in that, The ratio of the shortest vertical distance H2 from the removable U-shaped heat exchanger (4) to the bottom of the shell (1) to the vertical distance H1 from the horizontal section of the inner tube to the bottom of the shell (1) is 0.2-0.3:1; The outer diameter of the heat exchange tube is 19-32 mm; The center-to-center distance between two adjacent heat exchange tubes is 25-40 mm.

10. The mixing reactor according to any one of claims 1-9, characterized in that, A cooler is installed on the pipe connecting the reactant outlet (6) and the mixture inlet (303) in accordance with the material flow direction; An outer tube (201) is wound around the shell (1); The shell (1) is also provided with a heat exchange medium inlet (202) and a heat exchange medium outlet (203) that are connected to the external tracing pipe (201). The housing (1) is also provided with at least one mixture return port (7).

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