Microchannel device for a microreactor

Abstract

The application relates to the technical field of micro-channel reactors, in particular to a micro-channel device for a micro-reactor. The micro-channel device is provided with a reaction flow channel, a detection module, an injection mechanism, a discharge mechanism and a central control processor. When gas exists in the first reaction flow channel section, the central control processor adjusts the power of the liquid inlet pump, and when gas still exists in the first reaction flow channel section after the power of the liquid inlet pump is adjusted, the temperature of the first cooling unit is adjusted. When the average change rate of the pressure value in the second reaction flow channel section exceeds the preset interval, the adjusting unit is controlled to adjust the acid-base value in the second reaction flow channel section, and when the acid-base value change amount in the second reaction flow channel section exceeds the preset change amount threshold after the acid-base value in the second reaction flow channel section is adjusted, the temperature of the second cooling unit is adjusted. The reaction efficiency and effect of the reactants in the micro-channel reactor are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-channel reactor, in particular to a micro-channel device for micro-reactor. BACKGROUND

[0002] The micro-channel reactor is a kind of micro-reactor, usually composed of micro-pipeline and storage chamber, compared with traditional large reactor, it has the advantages of small volume, fast reaction speed, uniform reaction, easy control, etc., and is widely used in chemical, pharmaceutical, biological and other fields.

[0003] Chinese patent publication No. CN107551967A discloses a micro-channel device for micro-reactor, which comprises a micro-channel and at least one baffle arranged in the micro-channel, wherein the baffles are distributed along the axial direction of the micro-channel at equal intervals, and the diameter of the circumscribed circle of the baffle is the same as the inner diameter of the micro-channel; the fluid mixed in the micro-reactor flows into the micro-channel provided with the baffles; the baffles are arranged at 1-500 per meter in the micro-channel, and the distance between adjacent two baffles is 2-500 mm; the radial cross-sectional shape of the baffles along the micro-channel is in the shape of a Chinese character, a cross or a Japanese character, the axial projection area of the baffle is 30-95% of the radial cross-sectional area of the micro-channel, and the axial thickness of the baffle is 0.1-2.0 mm; the invention effectively strengthens the mixing and mass transfer rate of the fluid in the micro-channel by using the baffle structure, and the pressure drop of the tube is smaller than that of the filled micro-channel. The invention is suitable for gas-liquid, liquid-liquid reaction system, and can be applied to many industries such as chemistry, chemical industry and medicine.

[0004] However, the prior art still has the following problems:

[0005] In the process of preparing 2,5-dichloronitrobenzene by nitration reaction, the phenomena of the reactants flowing in the micro-channel device are different at different reaction stages, and the prior art does not consider adjusting the operating parameters of the corresponding parts of the reactor based on different reaction stages to improve the reaction efficiency and effect of the reactants in the micro-channel reactor. SUMMARY

[0006] To solve the above problems, the present application provides a micro-channel device for micro-reactor, which comprises:

[0007] The reaction flow channel is used for medium reaction, which comprises a first reaction flow channel section and a second reaction flow channel section, both of which are provided with spiral cavity regions for accommodating the medium for reaction, and the first reaction flow channel section is further provided with a first cooling unit on one side for cooling, and the second reaction flow channel section is further provided with a second cooling unit on one side for cooling and an adjusting unit for adjusting the pH value;

[0008] a detection module disposed in the reaction flow channel, configured to detect whether gas exists in the first reaction flow channel segment, a pressure value in the second reaction flow channel segment, and an acid-base value in the second reaction flow channel segment;

[0009] an injection mechanism configured to inject medium into the reaction flow channel, comprising a plurality of injection pipes disposed at different positions of the first reaction flow channel segment, each of the injection pipes being provided with a liquid inlet pump to control the injection rate of the medium;

[0010] an exhaust mechanism configured to exhaust the medium in the reaction flow channel, comprising an exhaust pipe disposed at the end of the second reaction flow channel segment;

[0011] a central control processor connected with the detection module, the injection mechanism, and the exhaust mechanism, comprising a first control unit and a second control unit,

[0012] the first control unit is configured to adjust the power of the liquid inlet pump when gas exists in the first reaction flow channel segment, and adjust the temperature of the first cooling unit under a first preset condition;

[0013] the second control unit is configured to control the adjustment unit to adjust the acid-base value in the second reaction flow channel segment when the average change rate of the pressure value in the second reaction flow channel segment exceeds a preset interval, and adjust the temperature of the second cooling unit under a second preset condition;

[0014] wherein the first preset condition is that gas still exists in the first reaction flow channel segment after adjusting the power of the liquid inlet pump, and the second preset condition is that the change amount of the acid-base value in the second reaction flow channel segment exceeds a preset change amount threshold after adjusting the acid-base value in the second reaction flow channel segment.

[0015] Further, the reaction flow channel comprises,

[0016] a first reaction flow channel segment, which is a flow channel segment in the reaction flow channel with a temperature higher than a preset temperature comparison threshold;

[0017] a second reaction flow channel segment, which is a flow channel segment in the reaction flow channel adjacent to the first reaction flow channel segment and having a temperature lower than the preset temperature comparison threshold.

[0018] Further, a buffer flow channel segment for eliminating gas in the first reaction flow channel segment is disposed at the connection between the first reaction flow channel segment and the second reaction flow channel segment, a one-way valve is disposed on the buffer flow channel segment to exhaust air outside the buffer flow channel segment, and the inner diameter of the buffer flow channel segment is greater than the inner diameters of the first reaction flow channel segment and the second reaction flow channel segment.

[0019] Further, the first control unit adjusts the power of the liquid inlet pump when gas exists in the first reaction flow channel segment, wherein,

[0020] The first control unit controls the power of the liquid inlet pump to decrease.

[0021] Further, the first control unit adjusts the temperature of the first cooling unit under a first preset condition, wherein,

[0022] The first control unit controls the temperature of the first cooling unit to decrease.

[0023] Further, the second control unit constructs a pressure change curve, wherein,

[0024] The second control unit constructs a pressure rectangular coordinate system, in which the pressure change curve is constructed, the pressure rectangular coordinate system being a coordinate system constructed with time as the horizontal axis and pressure value as the vertical axis.

[0025] Further, the second control unit determines the average change rate of the pressure value, wherein,

[0026] The second control unit constructs a plurality of straight lines in the pressure rectangular coordinate system, and divides the pressure change curve into a plurality of curve segments, each of the straight lines being parallel to the vertical axis and having equal intervals, and the average change rate V of the pressure value is calculated according to formula (1).

[0027]

[0028] In formula (1), P i+1 represents the pressure value at the midpoint of the i+1th curve segment, P i represents the pressure value at the midpoint of the ith curve segment, n represents the number of curve segments, and i represents an integer greater than 0.

[0029] Further, the second control unit controls the adjustment unit to adjust the pH value in the second reaction flow channel segment when the average change rate of the pressure value in the second reaction flow channel segment exceeds a preset interval, wherein,

[0030] The second control unit controls the adjustment unit to adjust the pH value in the second reaction flow channel segment, and the adjustment amount of the pH value is determined by the second control unit based on the average change rate.

[0031] Further, the second control unit adjusts the temperature of the second cooling unit under a second preset condition, wherein,

[0032] The second control unit controls the temperature of the second cooling unit to decrease, and the decrease amount is determined based on the difference between the change amount of the pH value in the second reaction flow channel segment and a preset change amount threshold.

[0033] Further, the medium injected into the reaction flow channel by the injection mechanism includes dichlorobenzene, nitric acid and concentrated sulfuric acid.

[0034] Compared with the prior art, the micro-channel reactor has the reaction flow channel, the detection module, the injection mechanism, the discharge mechanism and the central control processor, the central control processor adjusts the power of the liquid inlet pump when the gas exists in the first reaction flow channel section, adjusts the temperature of the first cooling unit when the gas still exists in the first reaction flow channel section after the power of the liquid inlet pump is adjusted, controls the adjustment unit to adjust the pH value in the second reaction flow channel section when the average change rate of the pressure value in the second reaction flow channel section exceeds the preset interval, and adjusts the temperature of the second cooling unit when the pH value change amount in the second reaction flow channel section exceeds the preset change amount threshold after the pH value in the second reaction flow channel section is adjusted, thereby improving the reaction efficiency and effect of the reactants in the micro-channel reactor.

[0035] Especially, in the present application, the reaction flow channel is divided into the first reaction flow channel section and the second reaction flow channel section according to the temperature in the reaction flow channel. In the actual situation of preparing 2,5-dichloronitrobenzene by using nitration reaction, the most heat is released in the initial stage of the reaction due to the high concentration of the reactants and the fast reaction rate, and the higher the temperature of the reaction flow channel, the more heat is released by the reactants. Therefore, the temperature in the reaction flow channel can represent the reaction stage of the reactants in the reaction flow channel, and the reaction flow channel can be reliably divided into the first reaction flow channel section and the second reaction flow channel section according to the temperature in the reaction flow channel, so that the corresponding adjustment and processing can be performed on different reaction flow channel sections in the later stage, and better reaction conditions can be provided for the reactants in different reaction stages, thereby ensuring the reaction efficiency and effect of the reactants in the micro-channel reactor.

[0036] Especially, in the present application, the inner diameter of the buffer flow channel section arranged at the connection between the first reaction flow channel section and the second reaction flow channel section is greater than the inner diameters of the first reaction flow channel section and the second reaction flow channel section. In the actual situation, when the reactants enter the second reaction flow channel section with a larger inner diameter from the first reaction flow channel section with a smaller inner diameter, the flow speed of the reactants is reduced, the pressure of the reactants is reduced, which is beneficial to the separation of the bubbles, and the design of the gradually increasing inner diameter can gradually lower the liquid level in the micro-channel reactor, thereby accelerating the separation of the bubbles. Therefore, the bubbles generated in the reaction process can be effectively removed through the buffer flow channel section with a larger inner diameter, thereby improving the reaction efficiency and effect of the reactants in the micro-channel reactor.

[0037] Especially, in the present application, the first control unit adjusts the power of the liquid inlet pump when gas exists in the first reaction flow channel section, and adjusts the temperature of the first cooling unit when gas still exists in the first reaction flow channel section after adjusting the power of the liquid inlet pump. In the actual process of preparing 2,5-dichloronitrobenzene by nitration reaction, the solubility of dissolved gas in the reactant decreases at the initial stage of the reaction due to the large amount of heat release, and bubbles are formed by the escape of the reactant, which affects the mixing and flow of the reactant, thereby leading to insufficient reaction, reducing the reaction yield and selectivity, affecting the product quality, and reducing the adaptability. Reducing the power of the liquid inlet pump can reduce the flow rate of the reactant, thereby reducing the collision frequency between the reactant molecules, slowing down the reaction rate, effectively reducing the bubbles in the reaction process, and reducing the temperature of the first cooling unit can effectively increase the solubility of the dissolved gas in the reactant and reduce the reaction rate, thereby reducing the bubbles in the reaction process. However, in actual situations, the effect of temperature on the reaction rate is greater than that of the flow rate of the reactant, therefore, the method of reducing the power of the liquid inlet pump is preferred to reduce bubbles, so as to effectively eliminate bubbles and improve the reaction efficiency and effect of the reactant in the micro-channel reactor on the basis of ensuring the reaction rate.

[0038] Especially, in the present application, the second control unit controls the adjustment unit to adjust the pH value in the second reaction flow channel section when the average change rate of the pressure value in the second reaction flow channel section exceeds the preset interval, and adjusts the temperature of the second cooling unit when the change amount of the pH value in the second reaction flow channel section exceeds the preset change amount threshold after adjusting the pH value in the second reaction flow channel section. In the actual process of preparing 2,5-dichloronitrobenzene by nitration reaction, the nitro compound produced in the reaction process spontaneously decomposes to occur a digestion reaction at the later stage of the reaction, which reduces the yield of the reaction product and even cannot obtain the ideal product. When the digestion reaction occurs, excessive pressure is generated in the reactor, therefore, when the average change rate of the pressure value exceeds the preset interval, it indicates that the digestion reaction occurs, and by adjusting the pH value in the second reaction flow channel section, the ion concentration in the reaction system is changed, thereby affecting the reaction rate and equilibrium constant. Under neutral or slightly basic conditions, the H+ ion concentration in the reaction system is low, which can reduce the occurrence of the digestion reaction, and when the digestion reaction occurs, the compounds in the reactant are decomposed into smaller molecules or ions, thereby affecting the pH value of the reactant and making the pH value of the reaction system unstable, i.e. the change amount of the pH value will exceed the preset change amount threshold. Therefore, if the digestion reaction is not inhibited, the pH value in the second reaction flow channel section will be unstable, i.e. the change amount of the pH value will exceed the preset change amount threshold, and further reducing the temperature of the second cooling unit is needed to reduce the energy in the reaction system to achieve the effect of inhibiting the digestion reaction. By adjusting the pH value and the temperature of the second cooling unit, the occurrence of the digestion reaction at the later stage of the reaction is effectively inhibited, thereby improving the reaction efficiency and effect of the reactant in the micro-channel reactor. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a microchannel device for a microreactor according to an embodiment of the invention.

[0040] Figure 2 This is a simplified structural diagram of the central control processor in an embodiment of the invention;

[0041] In the diagram, 1: injection tube, 2: first reaction flow channel section, 3: second reaction flow channel section, 4: discharge tube, and 5: buffer flow channel section. Detailed Implementation

[0042] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0043] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0044] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0045] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0046] Please see Figure 1 as well as Figure 2 As shown, this is a schematic diagram of the microchannel device structure for a microreactor and a simplified diagram of the central control processor structure according to an embodiment of the present invention. The microchannel device for a microreactor of the present invention includes:

[0047] The reaction flow channel for medium reaction includes a first reaction flow channel section 2 and a second reaction flow channel section 3, both of which are provided with spiral cavity regions for accommodating medium for reaction, and the first reaction flow channel section 2 is further provided with a first cooling unit on one side for temperature reduction, and the second reaction flow channel section 3 is further provided with a second cooling unit on one side for temperature reduction and an adjusting unit for adjusting pH value;

[0048] The detection module is arranged in the reaction flow channel and is used for detecting whether there is gas in the first reaction flow channel section 2, the pressure value in the second reaction flow channel section 3 and the pH value in the second reaction flow channel section 3.

[0049] The injection mechanism is used for injecting medium into the reaction flow channel and includes a plurality of injection pipes 1 arranged at different positions of the first reaction flow channel section 2, and each injection pipe 1 is provided with a liquid inlet pump to control the injection rate of the medium.

[0050] The discharge mechanism is used for discharging the medium in the reaction flow channel and includes a discharge pipe 4 arranged at the end of the second reaction flow channel section 3.

[0051] The central control processor is connected with the detection module, the injection mechanism and the discharge mechanism respectively and includes a first control unit and a second control unit.

[0052] The first control unit is used for adjusting the power of the liquid inlet pump when there is gas in the first reaction flow channel section 2 and adjusting the temperature of the first cooling unit under a first preset condition.

[0053] The second control unit is used for controlling the adjusting unit to adjust the pH value in the second reaction flow channel section 3 when the average change rate of the pressure value in the second reaction flow channel section 3 exceeds a preset range and adjusting the temperature of the second cooling unit under a second preset condition.

[0054] The first preset condition is that there is still gas in the first reaction flow channel section 2 after adjusting the power of the liquid inlet pump, and the second preset condition is that the change amount of the pH value in the second reaction flow channel section 3 exceeds a preset change amount threshold after adjusting the pH value in the second reaction flow channel section 3.

[0055] Specifically, the detection module includes a gas detection unit arranged in the first reaction flow channel section 2 for detecting whether there is gas in the first reaction flow channel section 2, a pressure detection unit arranged in the second reaction flow channel section 3 for detecting the pressure value in the second reaction flow channel section 3 and a pH value detection unit arranged in the second reaction flow channel section 3 for detecting the pH value in the second reaction flow channel section 3.

[0056] Specifically, the specific structure of the gas detection unit, the pressure detection unit and the pH detection unit is not limited, which can be respectively the combination structure of an ultrasonic sensor, a pressure sensor and a pH meter and a data interaction module, the data interaction module sends the detected gas, pressure value and pH value to the central control processor, which only needs to complete the function of detecting whether there is gas in the first reaction flow channel section 2 and the pressure value and pH value in the second reaction flow channel section 3, and details are not repeated.

[0057] Specifically, the specific structure of the cooling unit is not limited, which can be a micro-pore array embedded in the micro-channel reactor, or a temperature controller arranged on the periphery of the micro-channel, which only needs to complete the function of reducing the temperature of the reaction flow channel section, and details are not repeated.

[0058] Specifically, the specific structure of the adjusting unit is not limited, which can be the combination structure of an adjusting device with an acid-base adjusting valve, a pH meter and a data interaction module, the data interaction module sends the pH value detected by the pH meter in the second reaction flow channel section 3 to the central control processor, the central control processor controls the amount of acid-base added by controlling the acid-base adjusting valve, which only needs to complete the function of adjusting the pH value in the second reaction flow channel section 3, and details are not repeated.

[0059] Specifically, the specific form of the central control processor is not limited, which can be an external computer, each unit in the computer is a different function program, which only needs to complete the functions of data processing and data exchange, and details are not repeated.

[0060] Specifically, the reaction flow channel comprises,

[0061] The first reaction flow channel section 2 is a flow channel section in the reaction flow channel, the temperature of which is higher than the preset temperature comparison threshold value;

[0062] The second reaction flow channel section 3 is a flow channel section in the reaction flow channel, which is adjacent to the first reaction flow channel section 2 and has a temperature lower than the preset temperature comparison threshold value.

[0063] Specifically, in the present application, the reaction flow channel is divided into the first reaction flow channel section 2 and the second reaction flow channel section 3 according to the temperature in the reaction flow channel. In the actual situation of preparing 2, 5-dichloronitrobenzene by using nitration reaction, the most heat is released in the initial stage of the reaction due to the high concentration of the reactants, the fast reaction rate and other factors. The more heat released by the reactants, the higher the temperature of the reaction flow channel. Therefore, the temperature in the reaction flow channel can represent the reaction stage of the reactants in the reaction flow channel. Thus, the reaction stage of the reactants in the reaction flow channel can be reliably distinguished according to the temperature in the reaction flow channel, and the reaction flow channel can be reliably divided into the first reaction flow channel section 2 and the second reaction flow channel section 3 according to the reaction stage of the reactants in the reaction flow channel. This facilitates corresponding adjustment and processing of different reaction flow channel sections in the later stage, so as to provide better reaction conditions for the reactants in different reaction stages and ensure the reaction efficiency and effect of the reactants in the micro-channel reactor.

[0064] Specifically, the connecting part of the first reaction flow channel section 2 and the second reaction flow channel section 3 is provided with a buffer flow channel section 5 for eliminating gas in the first reaction flow channel section 2. A one-way valve is arranged on the buffer flow channel section 5 to discharge air outside the buffer flow channel section 5. The inner diameter of the buffer flow channel section 5 is greater than the inner diameter of the first reaction flow channel section 2 and the second reaction flow channel section 3.

[0065] Specifically, in the present application, the inner diameter of the buffer flow channel section 5 arranged at the connecting part of the first reaction flow channel section 2 and the second reaction flow channel section 3 is greater than the inner diameter of the first reaction flow channel section 2 and the second reaction flow channel section 3. In the actual situation, when the reactants enter the second reaction flow channel section 3 with a larger inner diameter from the first reaction flow channel section 2 with a smaller inner diameter, the flow speed of the reactants slows down, which reduces the pressure of the reactants and is beneficial to the separation of bubbles. In addition, the design of gradually increasing the inner diameter can gradually lower the liquid level in the micro-channel reactor, thereby accelerating the separation of bubbles. Therefore, the bubbles generated in the reaction process can be effectively removed through the buffer flow channel section 5 with a larger inner diameter, thereby improving the reaction efficiency and effect of the reactants in the micro-channel reactor.

[0066] Specifically, the first control unit adjusts the power of the liquid inlet pump when gas exists in the first reaction flow channel section 2, wherein,

[0067] The first control unit controls the power of the liquid inlet pump to decrease.

[0068] Specifically, in the present embodiment, the decrease amount p of the power of the liquid inlet pump is calculated based on the initial power P0 of the liquid inlet pump, and p = P0 × α1 is set, wherein α1 represents a first adjustment coefficient, and 0.1 ≤ α1 ≤ 0.3.

[0069] Specifically, in the embodiment, the first adjustment coefficient should be in a reasonable interval, in order to avoid excessive adjustment and to represent the adjustment effect, the person skilled in the art can select the value of the first adjustment coefficient from the interval [0.1, 0.3].

[0070] Specifically, the first control unit adjusts the temperature of the first cooling unit under the first preset condition, wherein,

[0071] The first control unit controls the temperature of the first cooling unit to decrease.

[0072] Specifically, in the embodiment, the temperature reduction t0 of the first cooling unit is calculated based on the initial temperature T0 of the first cooling unit, and t0=T0×α2 is set, wherein α2 represents the second adjustment coefficient, and 0.05≤α2≤0.1.

[0073] Specifically, in the embodiment, the second adjustment coefficient should be in a reasonable interval, in order to avoid excessive adjustment and to represent the adjustment effect, the person skilled in the art can select the value of the second adjustment coefficient from the interval [0.05, 0.1].

[0074] Specifically, in the present application, the first control unit adjusts the power of the liquid inlet pump when there is gas in the first reaction flow channel section 2, and adjusts the temperature of the first cooling unit when there is still gas in the first reaction flow channel section 2 after adjusting the power of the liquid inlet pump. In actual situations, during the preparation of 2,5-dichloronitrobenzene by nitration reaction, the solubility of dissolved gas in the reactant decreases at the initial stage of the reaction due to excessive heat release, and bubbles are formed by escaping from the reactant. The existence of bubbles will affect the mixing and flow of the reactant, thereby leading to insufficient reaction, reducing the reaction yield and selectivity, affecting the product quality, and reducing the adaptability. Reducing the power of the liquid inlet pump can reduce the flow rate of the reactant, thereby reducing the collision frequency between reactant molecules, slowing down the reaction rate, effectively reducing the bubbles in the reaction process, and reducing the temperature of the first cooling unit can effectively increase the solubility of the dissolved gas in the reactant and reduce the reaction rate, thereby reducing the bubbles in the reaction process. However, in actual situations, the influence of temperature on the reaction rate is greater than that of the flow rate of the reactant, therefore, the power of the liquid inlet pump is reduced to reduce the bubbles, so as to effectively eliminate the bubbles and improve the reaction efficiency and effect of the reactant in the micro-channel reactor on the basis of ensuring the reaction rate.

[0075] Specifically, the second control unit constructs a pressure change curve, wherein,

[0076] The second control unit constructs a pressure rectangular coordinate system, and constructs a pressure change curve in the pressure rectangular coordinate system. The pressure rectangular coordinate system is a coordinate system constructed with time as the horizontal axis and pressure value as the vertical axis.

[0077] Specifically, the second control unit determines an average change rate of the pressure value, wherein,

[0078] The second control unit constructs a plurality of straight lines in the pressure rectangular coordinate system, divides the pressure change curve into a plurality of curve segments, each of the straight lines is a straight line parallel to the longitudinal axis and having equal intervals, and calculates the average change rate V of the pressure value according to formula (1),

[0079]

[0080] In formula (1), P i+1 represents the pressure value at the midpoint of the i+1th curve segment, P i represents the pressure value at the midpoint of the ith curve segment, n represents the number of curve segments, and i represents an integer greater than 0.

[0081] Specifically, the second control unit controls the adjustment unit to adjust the pH value in the second reaction flow passage segment 3 when the average change rate of the pressure value in the second reaction flow passage segment 3 exceeds a preset interval [V1, V2].

[0082] The second control unit controls the adjustment unit to adjust the pH value in the second reaction flow passage segment 3, and the adjustment amount of the pH value is determined by the second control unit based on the average change rate;

[0083] The second control unit compares the average change rate V with the lower limit V1 of the preset interval and the upper limit V2 of the preset interval, 0

[0084] Under the first rate comparison condition, the second control unit determines that the adjustment amount of the pH value is a first adjustment amount b1.

[0085] Under the second rate comparison condition, the second control unit determines that the adjustment amount of the pH value is a second adjustment amount b2.

[0086] Under the third rate comparison condition, the second control unit determines that the adjustment amount of the pH value is a third adjustment amount b3.

[0087] Wherein, the first rate comparison condition is V≥V2, the second rate comparison condition is V1≤V<V2, and the third rate comparison condition is V<V1, b1>b2>b3.

[0088] Specifically, in the embodiment, the lower limit V1 of the preset interval and the upper limit V2 of the preset interval should be within a reasonable interval, in order to avoid overlarge or too small to determine the occurrence of misjudgment of the reaction, the person skilled in the art can select the value of V1 and V2 from the interval [1, 100], the interval unit is millibar / second, and the setting rate difference ratio Fv needs to be controlled within 0.3, which guarantees the differentiation to avoid too large difference, and sets Fv=(V2-V1) / V1.

[0089] Specifically, in the embodiment, b1-b3 are calculated based on the acidity and alkalinity A in the second reaction flow channel section 3 before adjusting the acidity and alkalinity in the second reaction flow channel section 3, and b1=A×α3, b2=A×α4, and b3=A×α5 are set, wherein α3 represents a third adjustment coefficient, α4 represents a fourth adjustment coefficient, and α5 represents a fifth adjustment coefficient, and 0.25<α5<α4<α3<0.5.

[0090] Specifically, in the embodiment, α3-α5 should be within a reasonable interval, and the person skilled in the art can select the value of α3-α5 from the interval [0.25, 0.5], and the first adjustment difference ratio Fα1 needs to be controlled within 0.3 when setting, which guarantees the differentiation to avoid too large difference, and sets Fα1=(αi+1-αi) / αi, wherein αi represents the ith adjustment coefficient, αi+1 represents the i+1 adjustment coefficient, and i=3, 4.

[0091] Specifically, the second control unit adjusts the temperature of the second cooling unit under a second preset condition, wherein,

[0092] The second control unit controls the temperature of the second cooling unit to decrease, and the decreasing amount is determined based on the difference value C of the acidity and alkalinity variation amount in the second reaction flow channel section 3 and the preset variation amount threshold value;

[0093] The second control unit compares the difference value C with a preset first difference value comparison threshold value C1 and a first difference value comparison threshold value C2, 0

[0094] Under the first difference value comparison condition, the second control unit determines that the temperature decreasing amount of the second cooling unit is a first temperature decreasing amount t1;

[0095] Under the second difference value comparison condition, the second control unit determines that the temperature decreasing amount of the second cooling unit is a second temperature decreasing amount t2;

[0096] Under the third difference value comparison condition, the second control unit determines that the temperature decreasing amount of the second cooling unit is a third temperature decreasing amount t3;

[0097] Wherein, the first rate contrast condition is C≥C2, the second rate contrast condition is C1≤C<C2, and the third rate contrast condition is C<C1, t1>t2>t3.

[0098] Specifically, in this embodiment, the first difference contrast threshold C1 and the second difference contrast threshold C2 should be within a reasonable range. To avoid misjudgment when determining whether the digestion reaction is inhibited, a person skilled in the art can select the values of C1 and C2 from the interval [1, 5], and set the rate difference difference ratio Fc to be controlled within 0.3 to ensure that the difference is not too large under the condition of distinguishing.

[0099] Specifically, in this embodiment, t1-t3 are calculated based on the initial temperature T0’ of the second cooling unit, and are set as t1=T0’×α6, t2=T0’×α7, and t3=T0’×α8, wherein α6 represents a sixth adjustment coefficient, α7 represents a seventh adjustment coefficient, and α8 represents an eighth adjustment coefficient, and 0.05<α8<α7<α6<0.25.

[0100] Specifically, in this embodiment, α6-α8 should be within a reasonable range. A person skilled in the art can select the values of α6-α8 from the interval [0.05, 0.25], and set the second adjustment difference ratio Fα2 to be controlled within 0.3 to ensure that the difference is not too large under the condition of distinguishing, and set Fα2=(αi+1-αi) / αi, wherein αi represents the ith adjustment coefficient, αi+1 represents the i+1 adjustment coefficient, and i=6, 7.

[0101] Specifically, in the present application, the second control unit controls the adjustment unit to adjust the pH value in the second reaction flow channel section 3 when the average change rate of the pressure value in the second reaction flow channel section 3 exceeds the preset interval, and adjusts the temperature of the second cooling unit when the change amount of the pH value in the second reaction flow channel section 3 exceeds the preset change amount threshold after adjusting the pH value in the second reaction flow channel section 3. In the actual situation of preparing 2,5-dichloronitrobenzene by nitration reaction, the nitro compound produced in the reaction process will spontaneously decompose and cause a degradation reaction in the later stage of the reaction, resulting in a decrease in the yield of the reaction product, and even the ideal product cannot be obtained. When the degradation reaction occurs, excessive pressure will be generated inside the reactor. Therefore, when the average change rate of the pressure value exceeds the preset interval, it indicates that the degradation reaction has occurred. By adjusting the pH value in the second reaction flow channel section 3 when the degradation reaction occurs, the ion concentration in the reaction system is changed, thereby affecting the reaction rate and equilibrium constant. Under neutral or slightly basic conditions, the H+ ion concentration in the reaction system is low, which can reduce the occurrence of the degradation reaction. When the degradation reaction occurs, the compounds in the reactants are decomposed into smaller molecules or ions, thereby affecting the pH value of the reactants, making the pH value of the reaction system unstable, i.e., the change amount of the pH value will exceed the preset change amount threshold. Therefore, if the degradation reaction is not inhibited, the pH value in the second reaction flow channel section 3 will be unstable, i.e., the change amount of the pH value will exceed the preset change amount threshold, and further reduction of the temperature of the second cooling unit is needed to reduce the energy in the reaction system, so as to achieve the effect of inhibiting the degradation reaction. By adjusting the pH value and the temperature of the second cooling unit, the occurrence of the degradation reaction in the later stage of the reaction is effectively inhibited, and the reaction efficiency and effect of the reactants in the microchannel reactor are improved.

[0102] Specifically, the medium injected by the injection mechanism into the reaction flow channel includes dichlorobenzene, nitric acid, and concentrated sulfuric acid.

[0103] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will all fall within the protection scope of the present application.

Claims

1. A microchannel device for use in a microreactor, characterized by, A method for preparing nitrobenzene by nitration reaction, comprising: a reaction channel for medium reaction, comprising a first reaction channel section and a second reaction channel section, each of which is provided with a spiral cavity region for accommodating medium for reaction, and one side of the first reaction channel section is further provided with a first cooling unit for cooling, and one side of the second reaction channel section is further provided with a second cooling unit for cooling and an adjusting unit for adjusting pH value; a detection module arranged in the reaction channel for detecting whether there is gas in the first reaction channel section, the pressure value in the second reaction channel section and the pH value in the second reaction channel section; an injection mechanism for injecting medium into the reaction channel, comprising a plurality of injection pipes arranged at different positions of the first reaction channel section, each of which is provided with a liquid inlet pump to control the injection rate of the medium; an exhaust mechanism for exhausting the medium in the reaction channel, comprising an exhaust pipe arranged at the end of the second reaction channel section; a central control processor connected with the detection module, the injection mechanism and the exhaust mechanism, comprising a first control unit and a second control unit, the first control unit is used to adjust the power of the liquid inlet pump when there is gas in the first reaction channel section, and adjust the temperature of the first cooling unit under a first preset condition; the second control unit is used to control the adjusting unit to adjust the pH value in the second reaction channel section when the average change rate of the pressure value in the second reaction channel section exceeds a preset interval, and adjust the temperature of the second cooling unit under a second preset condition; wherein the first preset condition is that there is still gas in the first reaction channel section after adjusting the power of the liquid inlet pump, and the second preset condition is that the change amount of the pH value in the second reaction channel section exceeds a preset change amount threshold after adjusting the pH value in the second reaction channel section; the first control unit adjusts the power of the liquid inlet pump when there is gas in the first reaction channel section, wherein the first control unit controls the power of the liquid inlet pump to decrease; the first control unit adjusts the temperature of the first cooling unit under a first preset condition, wherein the first control unit controls the temperature of the first cooling unit to decrease.

2. The microchannel device for a microreactor according to claim 1, wherein the reaction channel comprises, a first reaction channel section, which is a channel section in the reaction channel with a temperature higher than a preset temperature comparison threshold; a second reaction channel section, which is a channel section adjacent to the first reaction channel section in the reaction channel and has a temperature lower than the preset temperature comparison threshold.

3. The microchannel device for a microreactor of claim 1, wherein, The connection between the first reaction channel section and the second reaction channel section is provided with a buffer channel section for eliminating gas in the first reaction channel section, the buffer channel section is provided with a one-way valve to exhaust air outside the buffer channel section, and the inner diameter of the buffer channel section is greater than the inner diameter of the first reaction channel section and the second reaction channel section.

4. The microchannel device for a microreactor according to claim 3, wherein the second control unit constructs a pressure change curve, wherein The second control unit constructs a pressure rectangular coordinate system, and constructs a pressure change curve in the pressure rectangular coordinate system, wherein the pressure rectangular coordinate system is a coordinate system constructed with time as the horizontal axis and pressure value as the vertical axis.

5. The microchannel device for a microreactor of claim 4, wherein, The second control unit determines the average change rate of the pressure value, wherein, The second control unit constructs a plurality of straight lines in the pressure rectangular coordinate system, and divides the pressure change curve into a plurality of curve segments, wherein each straight line is parallel to the vertical axis and has equal spacing, and the average change rate V of the pressure value is calculated according to formula (1), （1）, In Equation (1), denotes a pressure value at a midpoint of an (i+1)th curve segment, denotes a pressure value at a midpoint of an ith curve segment, n denotes the number of curve segments, and i denotes an integer greater than 0.

6. The microchannel device for use in a microreactor according to claim 5, wherein, When the average change rate of the pressure value in the second reaction flow channel segment exceeds a preset interval, the second control unit controls the adjusting unit to adjust the pH value in the second reaction flow channel segment, wherein, The second control unit controls the adjusting unit to adjust the pH value in the second reaction flow channel segment, and the adjustment amount of the pH value is determined by the second control unit based on the average change rate.

7. The microchannel device for a microreactor of claim 6, wherein, When the second preset condition is met, the second control unit adjusts the temperature of the second cooling unit, wherein, The second control unit controls the temperature of the second cooling unit to decrease, and the decrease amount is determined based on the difference between the change amount of the pH value in the second reaction flow channel segment and a preset change amount threshold.

8. The microchannel device for use in a microreactor according to claim 7, characterized in that The medium injected into the reaction flow channel by the injection mechanism includes dichlorobenzene, nitric acid, and concentrated sulfuric acid.

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