A slightly trans-acetone cyanohydrin acylation reaction system and process

Abstract

The invention discloses a micro-trans acetone cyanohydrin acylation reaction system and process, belonging to the technical field of acylation reactions. The reaction system comprises a sulfuric acid feed metering pump, an acetone cyanohydrin feed metering pump, a microchannel reactor, a gas-liquid separation tank, and a vacuum pump. The microchannel reactor is formed by coupling a micro-mixing module and a micro-reaction module, and a demister is provided in the gas-liquid separation tank. The invention realizes molecular-level mixing, has high mass transfer and heat transfer efficiency, avoids local overheating, reduces polymerization side reactions, effectively reduces the occurrence of side reactions, greatly improves the purity of reaction products, reduces the risk of microchannel reactor clogging, and improves resource utilization.

Description

Technical Field

[0001] The present invention relates to the technical field of acylation reactions, and in particular to a slightly trans-type acetone cyanohydrin acylation reaction system and process. Background Art

[0002] The acylation reaction of acetone cyanohydrin with sulfuric acid to produce α-formamidoisopropyl hydrogen sulfate is a key and challenging step in the synthesis of methyl methacrylate (MMA). Due to the rapid reaction, high exotherm, high material density, and temperature sensitivity, conventional technology, despite numerous improvements, has limited its effectiveness in achieving long-term plant operation and has contributed little to product yield.

[0003] To improve the heat transfer efficiency of the acylation reaction, patent CN106588650A proposed a cyclic acylation apparatus and process using a shell-and-tube heat exchanger for cooling. To further improve this, patent CN104203392A proposed a two-stage cyclic reaction process and installed vortex flowmeters within the cooler tubes to improve heat transfer efficiency. However, due to the long residence time and high sulfuric acid ratio, the mass and heat transfer efficiencies could not meet the requirements for high heat release and rapid reaction.

[0004] The acylation of acetone cyanohydrin is a secondary reaction that takes only a few minutes to complete. However, existing industrial reactors are designed to have a residence time between 30 and 60 minutes. This is mainly due to low mass transfer efficiency and the inability to achieve microscale mixing. To improve the conversion rate, the only way is to increase the residence time of the material. However, increasing the residence time will lead to an increase in side reactions and a decrease in yield.

[0005] In response to the problems and shortcomings of the existing technology, this patent proposes a microchannel acetone cyanohydrin acylation reaction process to improve mass transfer and reaction efficiency, reduce reaction residence time and the probability of polymerization by-products.

[0006] The specific surface area of the fluid in the microreactor can reach 10 4 ~10 6 m 2 / m 3 , traditional reactors are generally 1000m 2 / m 3, 1 to 3 orders of magnitude higher than traditional reactors or industrial equipment. Due to the reduced fluid film thickness and increased specific surface area, the reactants in the microchannels can efficiently exchange heat with the wall, and the efficiency of heat exchange with the outside world far exceeds that of traditional reactors. This effectively and precisely controls the reaction temperature, concentrating the temperature distribution of the reactants in the microreactor near the ideal reaction temperature. This effectively avoids thermal effects such as localized overheating of the reactants and uneven heat transfer, and prevents the occurrence of some side reactions, thereby facilitating the synthesis of the target product and improving reaction selectivity. To this end, we propose a micro-trans acetone cyanohydrin acylation reaction system and process. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention provides a slightly trans-acetone cyanohydrin acylation reaction system and process, which overcome the deficiencies of the prior art and solve the problems existing in the background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: a micro-trans acetone cyanohydrin acylation reaction system, the reaction system comprising a sulfuric acid feed metering pump, an acetone cyanohydrin feed metering pump, a microchannel reactor, a gas-liquid separation tank, and a vacuum pump, the microchannel reactor being formed by coupling a micro-mixing module and a micro-reaction module, and a defoamer being provided in the gas-liquid separation tank;

[0009] The sulfuric acid feed metering pump is connected to one of the inlets of the micro-mixing module of the microchannel reactor, the outlet of the acetone cyanohydrin feed metering pump is connected to the other inlet of the micro-mixing module of the microchannel reactor, the outlet of the micro-mixing module of the microchannel reactor is connected to the inlet of the micro-reaction module, the outlet of the micro-reaction module is connected to the inlet of the gas-liquid separation tank, the top gas phase outlet of the gas-liquid separation tank is connected to the inlet of the vacuum pump, and the outlet of the vacuum pump is connected to a downstream discharging device;

[0010] The internal distribution holes of the micro-mixing module of the microchannel reactor are arranged by stacking multiple layers of thin layers. Each thin layer has a rectangular distribution channel. The opening size of different thin layers decreases geometrically from the inlet to the outlet. The opening directions of two adjacent thin layers are at a 90° angle. A cooling medium is provided outside the channel of the micro-mixing module. A micro-reaction channel layer and a cooling medium layer are provided on the micro-reaction module. The micro-mixing module is connected to the micro-reaction channel of the micro-reaction module through a capillary channel.

[0011] There are multiple micro-reaction modules, each of which has a layered structure. Micro-reaction channel layers and cooling medium layers are alternately arranged. Each micro-reaction channel layer is provided with multiple parallel micro-reaction channels. The micro-reaction channels are sinusoidal in shape. The diameter of the micro-reaction channels ranges from 100 μm to 1 mm, and the length of the micro-reaction channels ranges from 80 m to 100 m.

[0012] A demister is provided at the upper tangent line of the gas-liquid separation tank.

[0013] Preferably, the gas-liquid separation tank is an elliptical head tank with a length-to-diameter ratio of 4-6, and the demister is a wire mesh demister or a baffle demister.

[0014] Preferably, the demister is a baffle type demister, which has double-channel blades or three-channel blades, a thickness of 100-300 mm, a spacing between adjacent baffle blades of the demister of 2 mm to 3 mm, and a spacing between the bottom of the baffle and the liquid surface of 1 m to 2 m.

[0015] Another aspect of the present invention provides an acylation process for a slightly trans-type acetone cyanohydrin acylation reaction system, comprising the following steps:

[0016] Step 1: Sulfuric acid is metered and pressurized by a sulfuric acid feed metering pump before entering the micro-mixing module of the microchannel reactor. In the micro-mixing module, sulfuric acid is subjected to multiple fusion-diversion-fusion processes with acetone cyanohydrin metered and pressurized by an acetone cyanohydrin feed metering pump to form a molecularly uniform mixed liquid. The heat generated during the mixing reaction is removed by a cooling medium.

[0017] In step 2, the materials after uniform mixing are distributed into the micro-reaction module and react in the parallel micro-reaction channels. After the reaction, the materials enter the gas-liquid separation tank. The gas phase separated by flash evaporation rises and passes through the demister to recover the entrained liquid material. It is then discharged from the system by the vacuum pump and enters the downstream processing device. The liquid phase after degassing and separation contains the reaction product α-formamidoisopropyl hydrogen sulfate and surplus sulfuric acid and is discharged from the bottom of the gas-liquid separation tank and enters the downstream unit to continue the reaction.

[0018] Preferably, the reaction temperature of the microchannel reactor is 110°C-115°C.

[0019] Preferably, the flow velocity in the micro-reaction channel ranges from 0.09 m / s to 0.5 m / s.

[0020] Preferably, the inlet pressure of the microchannel reactor is 0.3 MPa(g)-1 MPa(g).

[0021] Preferably, the pressure of the gas-liquid separation tank is controlled within the range of 10-50 KPa (a), and the liquid level of the gas-liquid separation tank is controlled below 60%.

[0022] Beneficial effects of the present invention:

[0023] 1. The micro-mixing module is connected in series with the microchannel reactor module to carry out the acylation reaction of acetone cyanohydrin, achieving molecular-level mixing, high mass and heat transfer efficiency, and avoiding local overheating.

[0024] 2. The residence time is short, which is less than 1 / 10 of the residence time of traditional reactions. It reduces polymerization side reactions, effectively reduces the occurrence of side reactions, greatly improves the purity of reaction products, and saves investment and land.

[0025] 3. A gas phase vacuum is set at the tail end to avoid gas blockage and reduce the risk of clogging of the microchannel reactor.

[0026] 4. It avoids the defects of high investment, high energy consumption and low yield caused by a large amount of material circulation in the existing technology, and improves the utilization rate of resources.

[0027] The present invention realizes molecular-level mixing, has high mass transfer and heat transfer efficiency, avoids local overheating, reduces polymerization side reactions, effectively reduces the occurrence of side reactions, greatly improves the purity of reaction products, reduces the risk of microchannel reactor clogging, and improves resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic structural diagram of a slightly trans-type acetone cyanohydrin acylation reaction system of the present invention;

[0029] Figure 2 Schematic diagram of the micro-hybrid module structure of the present invention.

[0030] In the figure: 1. Microchannel reactor; 1.1. Micromixing module; 1.2. Microreaction module; 2. Gas-liquid separation tank; 2.1. Defoamer; 3. Vacuum pump; 4. Sulfuric acid feed metering pump; 5. Acetone cyanohydrin feed metering pump. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] See also Figure 1 A micro-trans acetone cyanohydrin acylation reaction system, comprising a sulfuric acid feed metering pump 4, an acetone cyanohydrin feed metering pump 5, a microchannel reactor 1, a gas-liquid separation tank 2, and a vacuum pump 3. The microchannel reactor 1 is formed by coupling a micro-mixing module 1.1 and a micro-reaction module 1.2. A defoamer 2.1 is provided in the gas-liquid separation tank 2.

[0033] The inlet of the sulfuric acid feed metering pump 4 is connected to the sulfuric acid feed pipeline, the outlet of the sulfuric acid feed metering pump 4 is connected to the inlet of the micro-mixing module 1.1 of the microchannel reactor 1 through a pipeline, the inlet of the acetone cyanohydrin feed metering pump 5 is connected to the acetone cyanohydrin feed pipeline, the outlet of the acetone cyanohydrin feed metering pump 5 is connected to another inlet of the micro-mixing module 1.1 of the microchannel reactor 1 through a pipeline, the outlet of the micro-mixing module 1.1 of the microchannel reactor 1 is connected to the inlet of the micro-reaction module 1.2, the outlet of the micro-reaction module 1.2 is connected to the inlet of the gas-liquid separation tank 2 through a pipeline, the top gas phase outlet of the gas-liquid separation tank 2 is connected to the inlet of the vacuum pump 3 through a pipeline, the bottom liquid phase outlet of the gas-liquid separation tank 2 is the reaction product discharge port, the outlet of the vacuum pump 3 is connected to the downstream discharge device, and the outlet tail gas of the vacuum pump 3 is discharged to the downstream processing device.

[0034] The internal distribution pore structure of the micro-mixing module 1.1 of the microchannel reactor 1 is shown as follows: Figure 2 As shown, the micro-mixing module 1.1 consists of a multi-layer stacked structure of thin layers. Each thin layer has rectangular distribution channels. The opening sizes of different thin layers decrease geometrically from the inlet to the outlet. The opening directions of two adjacent thin layers are at a 90° angle. A cooling medium is provided outside the channel of the micro-mixing module 1.1. The micro-reaction module 1.2 is provided with a micro-reaction channel layer and a cooling medium layer. The micro-mixing module 1.1 is connected to the micro-reaction channel of the micro-reaction module 1.2 through a capillary channel.

[0035] There are multiple micro-reaction modules 1.2, and the micro-reaction modules 1.2 have a layered structure. The micro-reaction channel layers and the cooling medium layers are arranged alternately. Each micro-reaction channel layer is provided with multiple parallel micro-reaction channels. The micro-reaction channels are sinusoidal in shape. The diameter of the micro-reaction channels ranges from 100μm to 1mm, and the length of the micro-reaction channels ranges from 80m to 100m.

[0036] The gas-liquid separation tank 2 is an elliptical head tank with an aspect ratio of 4-6. A demister 2.1 is provided at the upper tangent of the gas-liquid separation tank 2. The demister 2.1 is a wire mesh type demister or a baffle type demister.

[0037] When the demister 2.1 is a baffle type demister, the baffle type demister has double-channel blades or three-channel blades, the thickness of the demister 2.1 is 100-300 mm, the spacing between adjacent baffle blades of the demister 2.1 is 2 mm-3 mm, and the spacing between the bottom of the baffle and the liquid surface is 1 m-2 m. If it is too small, it is not conducive to liquid recovery and separation, and if it is too high, not only will the liquid recovery be slightly improved, but the equipment cost will also be increased.

[0038] An acylation process of a slightly trans-type acetone cyanohydrin acylation reaction system comprises the following steps:

[0039] Step 1: Sulfuric acid is metered and pressurized by the sulfuric acid feed metering pump 4 and then enters the micro-mixing module 1.1 of the microchannel reactor 1. In the micro-mixing module 1.1, the sulfuric acid is combined with the acetone cyanohydrin metered and pressurized by the acetone cyanohydrin feed metering pump 5 through multiple fusion-diversion-fusion processes to form a molecularly uniform mixed liquid. The heat generated during the mixing reaction is removed by the cooling medium.

[0040] In step 2, the evenly mixed materials are distributed into microreactor module 1.2, where they react within the parallel microreactor channels. The reacted materials then enter gas-liquid separator 2. The flash-evaporated gas phase rises through demister 2.1 to recover entrained liquid material. It is then discharged from the system by vacuum pump 3 and enters downstream processing equipment. The degassing and separation liquid phase, including the reaction product α-formamidoisopropyl hydrogen sulfate and excess sulfuric acid, is discharged from the bottom of gas-liquid separator 2 and enters downstream units for further reaction. The vacuum pump's primary function in this process is to create a tail vacuum, increasing the driving force of the microchannel reaction and preventing clogging.

[0041] The reaction temperature of the microchannel reactor 1 is 110°C-115°C. Since the microchannel improves the accuracy of temperature control and avoids local overheating problems, the reaction temperature can be accurately controlled in the high temperature area to maintain a faster reaction rate and reduce the reaction residence time.

[0042] The flow velocity in the micro-reaction channel ranges from 0.09 m / s to 0.5 m / s. If the flow velocity is too low, a complete laminar flow pattern cannot be formed. If the flow velocity is too high, the pressure drop is too large and the energy consumption is too high.

[0043] The inlet pressure of the microchannel reactor 1 is 0.3 MPa (g) - 1 MPa (g). If the inlet pressure is too low, the kinetic energy required for the flow of the reaction materials cannot be provided. If the inlet pressure is too high, energy consumption will be wasted.

[0044] The pressure of the gas-liquid separation tank 2 is controlled within the range of 10-50KPa (a) to increase the driving force of the micro-reverse channel, and the liquid level of the gas-liquid separation tank is controlled below 60% to ensure sufficient gas-liquid separation space.

[0045] The following examples illustrate the patent innovation, but are not limited to the examples.

[0046] Example 1:

[0047] equipment

[0048] The micro-mixing module (1.1) of the microchannel reactor (1) consists of multiple layers with rectangular channels, the last layer having a 10 μm aperture. The micro-reaction module (1.2) has a channel diameter of 500 μm, and the length of the micro-reaction channel is 80 m. The gas-liquid separation tank has an aspect ratio of 5, the demister is 150 mm thick, and the spacing between adjacent baffle blades is 2 mm. The spacing between the bottom of the baffle and the liquid surface is not less than 2 m.

[0049] Process parameters

[0050] Reaction temperature: 110°C, the flow rate of the material in the microchannel is 0.09 m / s, the inlet pressure of the microchannel reactor (1) is 0.3 MPa(g), the pressure of the gas-liquid separation tank (2) is controlled at 10 KPa(a), and the liquid level of the gas-liquid separation tank (2) is controlled at 40%.

[0051] The reaction results are shown in Table 1.

[0052] Example 2:

[0053] Except that the channel diameter of the micro-reaction module (1.2) is 200 μm, other equipment parameters and process operation parameters are the same as those in Example 1.

[0054] Example 3:

[0055] Except that the channel diameter of the micro-reaction module (1.2) is 900 μm, other equipment parameters and process operation parameters are the same as those in Example 1.

[0056] Example 4:

[0057] Except that the channel diameter of the micro-reaction module (1.2) is 900 μm and the flow rate in the micro-channel is 0.4 m / s, other equipment parameters and process operation parameters are the same as those in Example 1.

[0058] Example 5:

[0059] Except that the channel diameter of the micro-reaction module (1.2) is 1 mm, the flow rate in the micro-channel is 0.5 m / s, and the length of the micro-reaction channel is 100 m, other equipment parameters and process operation parameters are the same as those in Example 1.

[0060] Example 6:

[0061] Except that the length of the reaction channel is 100 m and the inlet pressure of the microchannel reactor (1) is 0.5 MPa(g), the other equipment parameters and process operation parameters are the same as those in Example 1.

[0062] Example 7:

[0063] Except that the length of the reaction channel is 100 m and the inlet pressure of the microchannel reactor (1) is 0.8 MPa(g), other equipment parameters and process operation parameters are the same as those in Example 1.

[0064] Example 8:

[0065] Except that the length of the reaction channel is 100 m, the inlet pressure of the microchannel reactor (1) is 1.0 MPa(g), and the flow rate in the microchannel is 0.5 m / s, other equipment parameters and process operation parameters are the same as those in Example 1.

[0066] Example 9:

[0067] Except that the reaction temperature was 115° C., other equipment parameters and process operation parameters were the same as those in Example 1.

[0068] Example 10:

[0069] Except for the reaction temperature of 113° C., other equipment parameters and process operation parameters are the same as those in Example 1.

[0070] Example 11:

[0071] Except that the pressure of the gas-liquid separation tank (2) is controlled at 30 kPa (a), other equipment parameters and process operation parameters are the same as those in Example 1.

[0072] Comparative Example 1:

[0073] The traditional kettle process with built-in cooling tubes uses normal pressure and the reaction temperature is controlled at 105°C.

[0074] Comparative Example 2:

[0075] Traditional external circulation cooling reaction process, normal pressure, reaction temperature controlled at 105℃.

[0076] The yields of the reactants prepared in the above examples and comparative examples were statistically analyzed to obtain the following table:

[0077] Table 1 Yield of reactants

[0078] α-Formamidoisopropyl hydrogen sulfate, % Example 1 97.6 Example 2 98.1 Example 3 97.3 Example 4 97.5 Example 5 97.2 Example 6 97.7 Example 7 97.5 Example 8 97.8 Example 9 97.4 Example 10 97.5 Example 11 97.2 Comparative Example 1 88.2 Comparative Example 2 93.1

[0079] It can be seen from the above table that the present invention effectively reduces the occurrence of side reactions and greatly improves the purity of the reaction product. The micro-mixing module of the present invention is connected in series with the microchannel reactor module to carry out the acylation reaction of acetone cyanohydrin, achieving molecular-level mixing, high mass transfer and heat transfer efficiency, and avoiding local overheating. The residence time of the present invention is short, and the residence time is less than 1 / 10 of the residence time of the traditional reaction, which reduces polymerization side reactions, effectively reduces the occurrence of side reactions, greatly improves the purity of the reaction product, saves investment and space. The tail end of the present invention is provided with a gas phase vacuum to avoid gas blockage and reduce the risk of clogging of the microchannel reactor. The present invention avoids the high investment, high energy consumption and low yield defects caused by a large amount of material circulation in the prior art, and improves the utilization rate of resources.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A slightly trans-type acetone cyanohydrin acylation reaction system, characterized in that: The reaction system comprises a sulfuric acid feed metering pump (4), an acetone cyanohydrin feed metering pump (5), a microchannel reactor (1), a gas-liquid separation tank (2), and a vacuum pump (3); the microchannel reactor (1) is formed by coupling a micro-mixing module (1.1) and a micro-reaction module (1.2); and a defoamer (2.1) is provided in the gas-liquid separation tank (2); The sulfuric acid feed metering pump (4) is connected to one of the inlets of the micro-mixing module (1.1) of the micro-channel reactor (1), the outlet of the acetone cyanohydrin feed metering pump (5) is connected to the other inlet of the micro-mixing module (1.1) of the micro-channel reactor (1), the outlet of the micro-mixing module (1.1) of the micro-channel reactor (1) is connected to the inlet of the micro-reaction module (1.2), the outlet of the micro-reaction module (1.2) is connected to the inlet of the gas-liquid separation tank (2), the top gas phase outlet of the gas-liquid separation tank (2) is connected to the inlet of the vacuum pump (3), and the outlet of the vacuum pump (3) is connected to a downstream discharge device; The micro-mixing module (1.1) of the microchannel reactor (1) has internal distribution holes, the micro-mixing module (1.1) is provided with a multi-layer stack of thin layers, each thin layer has a rectangular distribution channel, the opening size of the different thin layers decreases geometrically from the inlet to the outlet, and the opening directions of two adjacent thin layers are at a 90° angle, a cooling medium is provided outside the channel of the micro-mixing module (1.1), a micro-reaction channel layer and a cooling medium layer are provided on the micro-reaction module (1.2), and the micro-mixing module (1.1) is connected to the micro-reaction channel of the micro-reaction module (1.2) through a capillary channel; The micro-reaction modules (1.2) are multiple and have a layered structure. The micro-reaction channel layers and the cooling medium layers are alternately arranged. Each micro-reaction channel layer is provided with a plurality of parallel micro-reaction channels. The micro-reaction channels are sinusoidal in shape. The diameter of the micro-reaction channels ranges from 100 μm to 1 mm, and the length of the micro-reaction channels ranges from 80 m to 100 m. A defoamer (2.1) is provided at the upper tangent line of the gas-liquid separation tank (2).

2. A micro-trans acetone cyanohydrin acylation reaction system according to claim 1, characterized in that: The gas-liquid separation tank (2) is an elliptical head tank with a length-to-diameter ratio of 4-6, and the demister (2.1) is a wire mesh demister or a baffle demister.

3. A micro-trans acetone cyanohydrin acylation reaction system according to claim 2, characterized in that: The demister (2.1) is a baffle-type demister, which has double-channel blades or triple-channel blades. The thickness of the demister (2.1) is 100-300 mm, the spacing between adjacent baffle blades of the demister (2.1) is 2 mm-3 mm, and the spacing between the bottom of the baffle and the liquid surface is 1 m-2 m.

4. The acylation process of the micro-trans acetone cyanohydrin acylation reaction system according to any one of claims 1 to 3, comprising the following steps: Step 1: Sulfuric acid is metered and pressurized by a sulfuric acid feed metering pump (4) before entering the micro-mixing module (1.1) of the microchannel reactor (1). In the micro-mixing module (1.1), the sulfuric acid is subjected to multiple fusion-diversion-fusion processes with the acetone cyanohydrin metered and pressurized by an acetone cyanohydrin feed metering pump (5) to form a molecularly uniform mixed liquid. The heat generated during the mixing reaction is removed by the cooling medium. In step 2, the materials after uniform mixing are distributed into the micro-reaction module (1.2) and react in the parallel micro-reaction channels. After the reaction, the materials enter the gas-liquid separation tank (2). The gas phase separated by flash evaporation rises and passes through the defoamer (2.1) to recover the entrained liquid material. It is then discharged from the system by the vacuum pump (3) and enters the downstream processing device. The liquid phase after degassing and separation contains the reaction product α-formamidoisopropyl hydrogen sulfate and surplus sulfuric acid and is discharged from the bottom of the gas-liquid separation tank (2) and enters the downstream unit to continue the reaction.

5. The acylation process of the slightly trans-type acetone cyanohydrin acylation reaction system according to claim 4, characterized in that: The reaction temperature of the microchannel reactor (1) is 110°C-115°C.

6. The acylation process of a slightly trans-type acetone cyanohydrin acylation reaction system according to claim 4, characterized in that: The flow rate in the micro-reaction channel ranges from 0.09 m / s to 0.5 m / s.

7. The acylation process of a slightly trans-type acetone cyanohydrin acylation reaction system according to claim 4, characterized in that: The inlet pressure of the microchannel reactor (1) is 0.3 MPa(g)-1 MPa(g).

8. The acylation process of a slightly trans-type acetone cyanohydrin acylation reaction system according to claim 4, characterized in that: The pressure of the gas-liquid separation tank (2) is controlled within the range of 10-50 kPa (a), and the liquid level of the gas-liquid separation tank (2) is controlled below 60%.

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