A multi-stage microreactor with enhanced heat transfer and micromixing and its process flow

Abstract

This invention relates to a multi-stage microreactor and its process flow for enhancing heat transfer and micro-mixing. The multi-stage microreactor includes multiple three-way valves connected in series. Adjacent three-way valves are connected in series with a sleeve. The sleeve includes an outer tube and a first inner tube fitted inside the outer tube. The three-way valves have a first port, a second port, and a third port that are interconnected. By employing a special structural connection between the multi-stage series connections, this invention can effectively disperse the heat of reaction at each stage connection, effectively control the reaction temperature, and prevent safety accidents caused by excessively high reaction temperatures. It is applicable to, but not limited to, strongly exothermic reactions such as nitration and nitrosation. In addition, it can improve the micro-mixing and reaction effect of the system and precisely control the reaction time.

Description

Technical Field

[0001] This invention relates to a multi-stage microreactor and its process flow that can be used, but is not limited to, for enhancing heat transfer and micro-mixing. Background Technology

[0002] Over the past few decades, the application of microreactors has expanded rapidly. Compared to common batch processes and large-scale continuous production equipment, microreactors have shown unique advantages. To achieve good mass and heat transfer performance and ensure reaction throughput, the channel size of microreactors is typically between several hundred micrometers and one or two millimeters. Microreactors possess excellent heat and mass transfer performance and can easily and precisely control the contact time, shape, and size of the fluid interface. These miniaturized chemical reactors primarily provide controllable high-throughput methods for the synthesis of chemicals with high yields, stability, selectivity, low energy consumption, sample consistency, low reaction volume, and homogeneity. These properties make microreactors ideal for fast reactions, highly exothermic reactions, and even explosive reactions. Microreactors are considered one of the important pathways to achieve process intensification, continuous production, and micro-mixing.

[0003] Most existing reactors enhance micro-mixing by increasing centrifugal force during fluid flow to alter the fluid flow pattern and generate eddies. For example, Chinese Patent 200480022915.7 discloses a micro-fluid mixing device that uses a spiral reactor to deliver the fluids to be mixed in a laminar and substantially spiral flow pattern within the mixing channel. This device can mix fluids flowing in series or mix two or more fluids entering the device from different feed channels, thus enhancing micro-mixing to some extent. However, it places high demands on the dead volume within the device, as well as the flow rate, viscosity, and residence time of the mixed fluids. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention aims to provide a multi-stage microreactor and its process flow that enhances heat transfer and micro-mixing. This device and process flow can be applied to, but are not limited to, some strongly exothermic reactions such as nitration and nitrosation, as well as to enhance micro-mixing, control reaction time, and regulate reaction temperature.

[0005] The technical solution adopted in this invention is as follows:

[0006] This invention relates to a multi-stage microreactor that enhances heat transfer and micro-mixing. The microreactor comprises multiple three-way valves connected in series, with a sleeve connecting adjacent valves. Each sleeve includes an outer tube and a first inner tube fitted within the outer tube. Each three-way valve has a first port, a second port, and a third port that communicate with each other. A second inner tube is fitted between the second and third ports. The inlet end of the second inner tube extends through the second port of the three-way valve and communicates with a first feed pump. The outer peripheral wall of the inlet end of the second inner tube forms an annular channel with the inner peripheral wall of the second port of the three-way valve, and this annular channel communicates with the second feed pump. The outlet end of the second inner tube extends through the third port of the three-way valve and communicates with the first inner tube. Both ends of the outer tube are sealed and connected to the third port of the preceding three-way valve and the first port of the following three-way valve, respectively. The first inner tube is provided with micropores that allow fluid to pass through. A temperature sensor is connected to the output position of the third port of each three-way valve, and each temperature sensor is connected to a temperature acquisition device.

[0007] Preferably, the outer diameter of the first inner tube and the second inner tube is 0.5 mm and the inner diameter is 0.25 mm; the outer diameter of the outer tube is 1.6 mm and the inner diameter of the outer tube is 0.8 mm.

[0008] Preferably, the pore size of the micropores is in the range of 0.1-0.2 μm, and the porosity is in the range of 0.2-0.5.

[0009] Preferably, the above-mentioned sleeve is spiral, U-shaped, corrugated or sawtooth-shaped.

[0010] The present invention provides a process flow for a multi-stage microreactor that enhances heat transfer and micro-mixing, characterized by:

[0011] Ammonia and water are introduced into the second inner tube and annular channel respectively by the first and second feed pumps, with flow rates of 25 mL / min and 1 mL / min respectively. Temperature is collected by temperature sensors at the third port of each three-way valve to ensure that the mixing temperature is within a safe range and to ensure the safety of the experiment.

[0012] The present invention provides a process flow for a multi-stage microreactor that enhances heat transfer and micro-mixing, characterized by:

[0013] Preparation of acid buffer solution 1: Add an appropriate amount of concentrated sulfuric acid to deionized water to obtain a 0.01 mol / L acid buffer solution;

[0014] Preparation of Solution 2: A 0.2083 mol / L sodium hydroxide solution (standardized with potassium hydrogen phthalate) was obtained by dissolving solid sodium hydroxide in deionized water. Then, 784 mL of deionized water was added to 216 mL of sodium hydroxide solution to dilute it to obtain a 0.045 mol / L sodium hydroxide solution. 2.764 g of H3BO3 powder was then added and stirred until the solid was completely dissolved. Finally, 2.6828 g of KI and 0.6485 g of KIO3 were added successively and stirred until both components were completely dissolved to obtain Solution 2.

[0015] Solution 1 and Solution 2 are fed into the second inner tube and annular channel respectively by the first feed pump and the second feed pump. Solution 1 and Solution 2 are mixed in multiple stages in the shell reactor.

[0016] The present invention provides a process flow for a multi-stage microreactor that enhances heat transfer and micro-mixing, characterized by:

[0017] An anthraquinone solution and a nitrate-sulfur mixed acid solution of a certain concentration were prepared using concentrated sulfuric acid (95%~98% by mass) as the solvent. These solutions were fed into the second inner tube and the annular channel through the first and second feed pumps, respectively. The flow rates of the second inner tube and the annular channel were 1.5 mL / min and 2.0 mL / min, respectively. Effective mixing was achieved through a three-way valve. The mixed reaction solution underwent nitration in the reactor. The temperature of the pipeline at the mixing outlet was monitored in real time using a temperature sensor. The reaction solution at the outlet was diluted with a large amount of deionized water to quench the reaction. The acid was then removed with saturated NaHCO3, and the stop solution was adjusted until neutral.

[0018] Compared to a single mixing point, the multi-stage microreactor of this invention, which enhances heat transfer and micro-mixing, releases a large amount of reaction heat at the mixing point, causing a sharp rise in temperature. By using multiple mixing points, the heat can be distributed to multiple mixing points in a timely manner, ensuring experimental safety. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the connection structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the cross-sectional structure of the casing;

[0021] Figure 3 This is a schematic cross-sectional view of the three-way valve of the present invention;

[0022] Figure 4 This is a schematic diagram of the three types of sleeves;

[0023] Figure 5 This is a three-dimensional structural diagram of the inner tube;

[0024] Figure 6 This is a schematic diagram of the connection structure between two three-way valves and the sleeve (i.e.) Figure 1 (partial view)

[0025] Figure 7 This is a comparison chart of the strength data using a single tube and a sleeve. Detailed Implementation

[0026] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0027] This invention relates to a multi-stage microreactor that enhances heat transfer and micro-mixing. The microreactor comprises multiple three-way valves 1 connected in series. A sleeve 2 is connected in series between adjacent three-way valves 1. Each sleeve 2 includes an outer tube 201 and a first inner tube 202 fitted inside the outer tube. Each three-way valve has a first port 101, a second port 102, and a third port 103 that are interconnected. A second inner tube 3 is fitted between the second port 102 and the third port 103. The inlet end of the second inner tube 3 extends out of the second port of the three-way valve and connects to a first feed pump 4. The outer peripheral wall of the inlet end and the inner peripheral wall of the second port of the three-way valve form an annular channel 5. The annular channel 5 is connected to the second feed pump 6. The outlet end of the second inner tube 3 passes through the third port 103 of the three-way valve and is connected to the first inner tube 202. The two ends of the outer tube 201 are respectively sealed and connected to the third port of the previous stage three-way valve and the first port of the subsequent stage three-way valve. The first inner tube is provided with micropores 7 that can pass through the fluid. The output position of the third port of each three-way valve is connected to a temperature sensor 8. Each temperature sensor is connected to a temperature acquisition device 9.

[0028] Specifically, the outer diameter of the first inner tube and the second inner tube is 0.5 mm and the inner diameter is 0.25 mm; the outer diameter of the outer tube is 1.6 mm and the inner diameter of the outer tube is 0.8 mm; the pore size of the micropores is in the range of 0.1-0.2 μm and the porosity is in the range of 0.2-0.5; the sleeve is spiral, U-shaped, corrugated or sawtooth.

[0029] The present invention provides a process flow 1 for a multi-stage microreactor that enhances heat transfer and micro-mixing. It employs a multi-stage series-connected sleeve structure, with an inner tube having an outer diameter of 0.5 mm and an inner diameter of 0.25 mm; and an outer tube having an outer diameter of 1.6 mm and an inner diameter of 0.8 mm. Ammonia and water are introduced into the second inner tube and an annular channel respectively via a first feed pump and a second feed pump, with flow rates of 25 mL / min and 1 mL / min respectively. Since the reaction between ammonia and water generates a large amount of heat, multi-stage processing is necessary. Compared to a single mixing point, where the reaction rapidly releases a large amount of heat that is difficult to disperse quickly, potentially causing safety issues, multi-stage processing disperses the concentrated heat to each stage. Temperature is collected by a temperature sensor after the mixing point to ensure the mixing temperature remains within a safe range, guaranteeing experimental safety.

[0030] The process flow 2 of the multi-stage microreactor for enhancing heat transfer and micro-mixing according to the present invention:

[0031] It adopts a multi-stage series sleeve structure, with an inner tube outer diameter of 0.4mm and an outer tube outer diameter of 0.2mm; the outer tube outer diameter is 1.6mm and the outer tube inner diameter is 0.8mm;

[0032] Preparation of acid buffer solution 1: Add an appropriate amount of concentrated sulfuric acid to deionized water to obtain a 0.01 mol / L acid buffer solution;

[0033] Preparation of Solution 2: A 0.2083 mol / L sodium hydroxide solution (standardized with potassium hydrogen phthalate) was obtained by dissolving solid sodium hydroxide in deionized water. Then, 784 mL of deionized water was added to 216 mL of sodium hydroxide solution to dilute it to obtain a 0.045 mol / L sodium hydroxide solution. 2.764 g of H3BO3 powder was then added and stirred until the solid was completely dissolved. Finally, 2.6828 g of KI and 0.6485 g of KIO3 were added successively and stirred until both components were completely dissolved to obtain Solution 2.

[0034] Solution 1 and Solution 2 are fed into the second inner tube and annular channel respectively by the first feed pump and the second feed pump. Solution 1 and Solution 2 are mixed in multiple stages in the shell reactor.

[0035] Compared to ordinary three-way T-type single-pipe mixing and single-mixing-point sleeve structures, the multi-stage microreactor structure, with its multiple mixing points, significantly improves mixing performance.

[0036] The process flow 3 of the multi-stage microreactor for enhanced heat transfer and micro-mixing in this invention:

[0037] It adopts a multi-stage series sleeve structure, with an inner tube outer diameter of 0.4mm and an inner tube inner diameter of 0.3mm; an outer tube outer diameter of 1.4mm and an outer tube inner diameter of 0.8mm;

[0038] An anthraquinone solution and a nitrate-sulfur mixed acid solution of a certain concentration were prepared using concentrated sulfuric acid (95%~98% by mass) as the solvent. These solutions were fed into the second inner tube and the annular channel through the first and second feed pumps, respectively. The flow rates of the second inner tube and the annular channel were 1.5 mL / min and 2.0 mL / min, respectively. Effective mixing was achieved through a three-way valve. The mixed reaction solution underwent nitration in the reactor. The temperature of the pipeline at the mixing outlet was monitored in real time using a temperature sensor. The reaction solution at the outlet was diluted with a large amount of deionized water to quench the reaction. The acid was then removed with saturated NaHCO3, and the stop solution was adjusted until neutral.

[0039] Compared to a single mixing point, the multi-stage microreactor of this invention, which enhances heat transfer and micro-mixing, releases a large amount of reaction heat at the mixing point, causing a sharp rise in temperature. By using multiple mixing points, the heat can be distributed to multiple mixing points in a timely manner, ensuring experimental safety.

Claims

1. A multi-stage microreactor that enhances heat transfer and micro-mixing, characterized in that: The device includes multiple three-way valves connected in series. Adjacent three-way valves are connected in series with a sleeve. The sleeve includes an outer tube and a first inner tube fitted inside the outer tube. Each three-way valve has a first port, a second port, and a third port that are interconnected. A second inner tube is fitted between the second port and the third port. The inlet end of the second inner tube passes through the second port of the three-way valve and connects to a first feed pump. The outer peripheral wall of the inlet end of the second inner tube forms an annular channel with the inner peripheral wall of the second port of the three-way valve. This annular channel connects to the second feed pump. The outlet end of the second inner tube passes through the third port of the three-way valve and connects to the first inner tube. Both ends of the outer tube are sealed and connected to the third port of the preceding three-way valve and the first port of the following three-way valve, respectively. The first inner tube is provided with micropores that allow fluid to pass through. A temperature sensor is connected to the output position of the third port of each three-way valve, and each temperature sensor is connected to a temperature acquisition device.

2. The multi-stage microreactor for enhanced heat transfer and micro-mixing according to claim 1, characterized in that: The outer diameter of the first inner tube and the second inner tube is 0.5 mm, and the inner diameter is 0.25 mm; the outer diameter of the outer tube is 1.6 mm, and the inner diameter of the outer tube is 0.8 mm.

3. The multi-stage microreactor with enhanced heat transfer and micro-mixing according to claim 1, characterized in that: The pore size of the micropores ranges from 0.1 to 0.2 μm, and the porosity ranges from 0.2 to 0.

5.

4. The multi-stage microreactor for enhanced heat transfer and micro-mixing according to claim 1, characterized in that: The sleeve is spiral, U-shaped, corrugated, or sawtooth-shaped.

5. A process flow for a multi-stage microreactor with enhanced heat transfer and micro-mixing as described in any one of claims 1-4, characterized in that: Ammonia and water are introduced into the second inner tube and annular channel respectively by the first and second feed pumps, with flow rates of 25 mL / min and 1 mL / min respectively. Temperature is collected by temperature sensors at the third port of each three-way valve to ensure that the mixing temperature is within a safe range and to ensure the safety of the experiment.

6. A process flow for a multi-stage microreactor with enhanced heat transfer and micro-mixing as described in any one of claims 1-4, characterized in that: Preparation of acid buffer solution 1: Add an appropriate amount of concentrated sulfuric acid to deionized water to obtain a 0.01 mol / L acid buffer solution; Preparation of Solution 2: A 0.2083 mol / L sodium hydroxide solution was obtained by dissolving solid sodium hydroxide in deionized water, and standardized with potassium hydrogen phthalate. Then, 784 mL of deionized water was added to 216 mL of sodium hydroxide solution to dilute it to obtain a 0.045 mol / L sodium hydroxide solution. 2.764 g of H3BO3 powder was added and stirred until the solid was completely dissolved. Finally, 2.6828 g of KI and 0.6485 g of KIO3 were added successively and stirred until both components were completely dissolved to obtain Solution 2. Acid buffer solution 1 and solution 2 are fed into the second inner tube and annular channel respectively by the first feed pump and the second feed pump. Acid buffer solution 1 and solution 2 are mixed in multiple stages in the shell reactor.

7. A process flow for a multi-stage microreactor with enhanced heat transfer and micro-mixing as described in any one of claims 1-4, characterized in that: An anthraquinone solution and a nitrate-sulfur mixed acid solution of a certain concentration were prepared using concentrated sulfuric acid with a mass fraction of 95%~98% as the solvent. These solutions were fed into the second inner tube and the annular channel through the first and second feed pumps, respectively. The flow rates of the second inner tube and the annular channel were 1.5 mL / min and 2.0 mL / min, respectively. Effective mixing was achieved through a three-way valve. The mixed reaction solution underwent a nitration reaction in the reactor. The temperature of the pipeline at the mixing outlet was monitored in real time using a temperature sensor. The reaction solution at the outlet was diluted with a large amount of deionized water to quench the reaction. The acid was then removed with saturated NaHCO3, and the stop solution was adjusted until neutral.

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