A micro flow field device and method for enhancing high viscosity, strong exothermic reactions

Abstract

This invention provides a microfluidic device and method for enhancing high-viscosity, highly exothermic reactions. The microfluidic device comprises a reaction channel with two inlet channels and a mixing channel. The reaction channel has two inlets and one outlet. A cooling channel surrounds the entire reaction channel, forming a sleeve with two inlets and one outlet. The microreactor has a rectangular cross-section. The front section of the reaction channel is a baffle structure with intervals, while the rear section is a spiral mixing structure. This microchannel structure achieves highly efficient mass and heat transfer during glycerol nitration, providing a safe, efficient, and easily scalable microfluidic device, offering a universal solution for industrial processes such as organic synthesis, drug preparation, and highly hazardous exothermic reactions.

Description

Technical Field

[0001] This invention relates to the field of chemical reaction equipment, specifically to a microfluidic field device and method for enhancing high-viscosity, strongly exothermic reactions. Background Technology

[0002] Microchemical technology, as a cutting-edge interdisciplinary field in chemical engineering, focuses on utilizing microchannel reactors to achieve microscale transport and chemical reaction processes. Compared to traditional chemical equipment, microchemical systems significantly reduce the dispersion scale of the system, effectively enhancing mixing, mass transfer, and heat transfer efficiency, and greatly improving process controllability and reaction rates. Simultaneously, this technology can significantly enhance the safety of chemical production, reduce by-product generation, promote process intensification and system miniaturization, thereby achieving breakthroughs in energy and resource utilization efficiency and ultimately reaching the sustainable development goal of energy conservation and emission reduction. For these reasons, microchemical technology has been applied on a large scale in multiple industrial fields, including but not limited to the controllable synthesis of nanomaterials, efficient reaction-separation coupling processes, continuous synthesis of fine organic chemicals, and green production of plasticizers.

[0003] The advantages of microreactor technology stem from its extremely high specific surface area and extremely short diffusion distance, which enables heat and mass transfer rates several orders of magnitude higher than those of traditional reactors. This enhanced transfer characteristic allows the reaction system to operate under near-isothermal conditions, effectively suppressing side reactions and the risk of thermal runaway caused by local overheating. The precise temperature control capability of microreactors is particularly critical in reactions involving strong exothermic processes or those that are temperature-sensitive. Furthermore, microreactor technology typically employs a continuous flow model, avoiding the feeding, waiting, and unloading stages of batch operations, significantly improving production efficiency and system stability, and providing an ideal platform for process automation and digital control.

[0004] Nitroglycerin (GTN), a core raw material in explosives and pharmaceuticals, has long been hampered by technical bottlenecks in its traditional batch reactor production process, including low inherent safety and poor product selectivity. The nitration reaction itself is highly exothermic and exhibits rapid reaction kinetics. In traditional production processes, uneven mixing or insufficient heat dissipation can easily lead to localized overheating, potentially causing decomposition or even explosions. Furthermore, the significant viscosity and density differences between the mixed acid (nitric acid and sulfuric acid) and glycerin in the reaction system make it difficult to achieve uniform molecular-level contact using traditional stirring methods. This hinders further improvements in reaction selectivity and yield, while also increasing the accumulation of byproducts and the burden of post-processing.

[0005] Microchemical technology, with its enhanced microscale transport and precise temperature control capabilities, is considered a breakthrough path to resolve the aforementioned contradictions. By precisely metering and efficiently mixing reactants within microchannels, the heat of reaction can be rapidly dissipated, thereby achieving amplification of the reaction process and ensuring product quality consistency while improving safety. However, its application in high-viscosity, fast-reaction systems still faces key challenges, especially in complex processes involving significant differences in material rheology, susceptibility to clogging, or the need for gradient control.

[0006] Current mainstream microreactors (such as Y-type / T-type structures) are limited in their ability to handle high viscosity-difference systems of glycerol and mixed acids due to insufficient laminar mixing efficiency and structural reliability defects. Specifically, high-viscosity fluids tend to form viscosity-dominated laminar flow within microchannels, resulting in slow diffusion mixing and insufficient renewal of the acid-alcohol interface. Reactants fail to fully mix at the microscopic level before reacting, causing local deviations from the ideal stoichiometric ratio and exacerbating side reactions. Although static baffle designs (such as cylindrical / flat plates) can reduce processing costs and introduce vortices through flow channel variations, the induced turbulence intensity is usually insufficient, making it difficult to achieve flexible gradient control of the acid-alcohol ratio in time and space. Furthermore, during long-term operation, high-viscosity media tend to accumulate in baffle dead zones or joints, gradually carbonizing or solidifying, causing blockages and affecting the stability of continuous production and the lifespan of the device. Therefore, existing micromixing structures have low side reaction suppression efficiency when dealing with demanding systems like nitroglycerin production, severely limiting their potential for industrial application. Summary of the Invention

[0007] Purpose of the invention: The technical problem to be solved by the present invention is to address the shortcomings of the prior art by proposing a microfluidic field device and method to enhance the mass and heat transfer of high-viscosity, highly exothermic reactions, thereby constructing a safe, efficient and easily scalable microfluidic chemical reactor, and providing a universal solution for industrial processes such as mechanical synthesis, drug preparation, and high-risk exothermic reactions.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A microfluidic field device for enhancing high-viscosity, highly exothermic reactions is characterized by comprising a sleeve (1) and a baffle and spiral mixing structure (2) in a reaction channel; all channels are square through holes, and the sleeve is formed by a cooling channel surrounding the entire reaction channel, the cooling channel having two inlets and one outlet, as well as a supporting structure. The reaction channel has two inlets and one outlet, the front section of the reaction channel is a baffle structure with a gap, and the rear section is a spiral mixing structure. The reaction channel is built into the center of the cooling channel, two streams of cooling water enter from the two inlets, and the cooling water flows out from the outlet after passing through the channel; at least two streams of reaction fluid enter the mixing channel through the inlet channel respectively for mixing, and the mixed fluid flows out through the outlet.

[0010] Furthermore, in the microfluidic field device for enhancing high viscosity and strong exothermic reaction, the longitudinal length L0 of the cooling channel of the sleeve (1) is 280-320mm, and the inner diameter D1 of the cooling channel is 5-10mm; the longitudinal length L0 of the reaction channel is 280-320mm, and the inner diameter D2 of the reaction channel is 1-4mm.

[0011] Furthermore, in the aforementioned microfluidic field device for enhancing high-viscosity, strongly exothermic reactions, the baffle structure of the reaction channel is a square baffle (length a1 is 2-8 mm, width b1 is 0.1-1 mm, height c1 is 1-6 mm), and it is located in the XZ plane; the number of reaction channels N1 is 20-40; the baffle spacing L is 0.1-2 mm; and the distance L between the spiral mixing structure and the baffle structure is... s It is 0.1 to 2 mm.

[0012] Furthermore, the spiral mixing structure of the reaction channel (length a2 is 7-15 mm, width b2 is 0.1-2 mm, height c2 is 1-6 mm) is twisted by 90°-270°; the number of spiral mixing structures N2 is 2-10; the spacing L m The diameter is 0.1-2 mm, and the pairs are arranged alternately at 0-90°.

[0013] Furthermore, the cooling channel includes a support structure; the support structure is square (length a3 is 3-8mm, width b3 is 0.1-2mm, height c3 is 1-6mm); the support structure is located in the XZ and YZ planes respectively, and forms angles of 0-180° with the Y-axis and X-axis, with a spacing L between structures on the same plane. n The thickness is 20-40mm; the number of support structures N3 is 20-40, and they are arranged in pairs with respect to the mixing channel at 0-180° to each other.

[0014] Furthermore, the present invention provides an application of a microfluidic field device for enhancing high-viscosity, strongly exothermic reactions in any of the following systems:

[0015] (1) Nitration of glycerol; or,

[0016] (2) Parallel scale-up of glycerol nitration

[0017] The fluid properties and boundary conditions of the glycerol nitration reaction system are as follows: mixed acid (98% concentrated sulfuric acid H2SO4 mass fraction 80-90%; 98% fuming nitric acid HNO3 mass fraction 10-20%), glycerol-nitric acid molar ratio 1:2-1:8, glycerol flow rate 0.0008-0.0015 (m / s), mixed acid flow rate 0.01-0.035 (m / s), inlet temperature and initialization temperature 1-5℃; cooling water main channel matching flow rate 0.02-0.2 (m / s), cooling water inlet flow rate 0.02-0.2 (m / s), cooling water temperature 1-5℃.

[0018] The parallel scale-up application of glycerol nitration involves a 12-channel parallel amplification of the microfluidic device. Its fluid properties and boundary conditions are as follows: glycerol inlet Inlet-1 flow rate 0.05–0.5 mL / min, mixed acid inlet Inlet-2 flow rate 1–10 mL / min, and cooling water combined flow rate from the two inlets Inlet-A and Inlet-B 100–500 mL / min. Therefore, the initial material temperature is -10 to -1℃.

[0019] The parallel scale-up application of glycerol nitration involves a parallel amplification of eight microfluidic field devices. The fluid properties and boundary conditions are as follows: the flow rate of each material (glycerol and mixed acid) is set to 1.8 times the flow rate of a single material; the flow rate at the glycerol inlet-1 is 0.09–0.9 mL / min; the flow rate at the mixed acid inlet-2 is 1.8–18 mL / min; the flow rate of the coolant in each channel is 1.5 times the flow rate of a single coolant; the combined flow rate of the two cooling water inlets, Inlet-A and Inlet-B, is 150–750 mL / min; and the initial temperature of all materials is -20 to -11 °C.

[0020] The parallel scale-up application of glycerol nitration involves a four-channel parallel amplification of the microfluidic field device. The fluid properties and boundary conditions are as follows: the flow rate of each material (glycerol and mixed acid) is set to 3.5 times the flow rate of a single material; the flow rate at the glycerol inlet-1 is 0.175–1.75 mL / min; the flow rate at the mixed acid inlet-2 is 3.5–35 mL / min; the flow rate of the coolant in each channel is twice the flow rate of a single coolant; the combined flow rate of the two cooling water inlets, Inlet-A and Inlet-B, is 200–1000 mL / min; and the initial temperature of all materials is adjusted to -25–-16°C.

[0021] This invention proposes a microfluidic field device and method to enhance high-viscosity, highly exothermic reactions. By combining a Y-shaped structure design with a gradually changing contact mixing channel, it overcomes the problem of poor mass and heat transfer efficiency in traditional microfluidic field devices for high-viscosity, highly exothermic reactions. The design employs a dual-inlet Y-shaped reaction channel and a sleeve-type cooling channel working synergistically. The front section features baffles with gradually increasing intervals to achieve progressive material contact, while the rear section uses a spiral mixing structure to ensure complete reaction, effectively solving the problem of temperature runaway caused by the intense exothermic reaction. Compared to serpentine microchannel reactors, this microfluidic field device structure achieves precise temperature control and efficient mixing within a regular straight channel, while also being simple in structure, easy to manufacture, and economical to maintain. Its ultimate goal is to construct a safe, efficient, and easily scalable microfluidic chemical reaction device, providing a reliable solution for the industrial production of high-risk nitration reactions such as nitroglycerin. Attached Figure Description

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer. Figure 1 This is a longitudinal cross-sectional schematic diagram of a microfluidic field device for enhancing high-viscosity, strongly exothermic reactions according to the present invention. The microfluidic field device has a length L0 of 280–320 mm, a width D1 of 5–10 mm, and a wall thickness D of 0.1–2 mm; the reaction channel has a width D2 of 1–4 mm; the upper part of the inlet has a large inlet Inlet-A for coolant inlet and a small inlet Inlet-1 for mixed alcohol inlet; the lower part of the inlet has a large inlet Inlet-B for coolant inlet and a small inlet Inlet-2 for mixed acid inlet; the outlet has a large outlet Outlet-C for coolant outlet and a small outlet Outlet-3 for product outlet; the two sides of the channel are cooling channels containing heat dissipation fins and support structures; the middle is the reaction channel containing an internal baffle with a length a1 of 2–8 mm and a spiral enhanced mixing structure with a length a2 of 7–15 mm.

[0023] Figure 2 This is a schematic diagram of the overall structure of a microfluidic field device for enhancing high-viscosity, strongly exothermic reactions according to the present invention.

[0024] Figure 3 This is a schematic diagram of the structural parameters of a microfluidic field device for enhancing high-viscosity, strongly exothermic reactions according to the present invention. Figure (a) shows the inlet of the cooling channel and the reaction channel; Figure (b) is a cross-sectional view of the device; Figure (c) shows the outlet of the cooling channel and the reaction channel; and Figure (d) is a schematic diagram of the baffles and spiral structure in the channel.

[0025] Figure 4 Temperature distribution (a) and nitroglycerin mass fraction distribution (b) of the nitration reaction in the reaction channel.

[0026] Figure 5 The highest global temperature in a single-channel simulation is 45℃.

[0027] Figure 6 The highest global temperature in a single-channel simulation is 39℃.

[0028] Figure 7 The highest global temperature in a single-channel simulation was 48℃. Detailed Implementation

[0029] Example 1: Microfluidic device and method for glycerol nitration reaction.

[0030] like Figure 2 As shown, a microreactor for glycerol nitration is specifically designed. The baffle structure of the reaction channel is a square baffle (length a1 = 5 mm, width b1 = 0.5 mm, height c1 = 2.9 mm) and is located in the XZ plane; the number of reaction channels N1 is 32; the spacing L1 between baffles 1-3 is 0.1 mm, the spacing L2 between baffles 4-6 is 0.2 mm, the spacing L3 between baffles 7-10 is 0.25 mm, the spacing L4 between baffles 11-15 is 0.4 mm, the spacing L5 between baffles 16-20 is 0.55 mm, the spacing L6 between baffles 21-25 is 0.7 mm, the spacing L7 between baffles 26-30 is 0.85 mm, and the spacing L8 between baffles 31-36 is 1 mm; the distance L between the spiral mixing structure and the baffle structure is... s The diameter is 0.5 mm. The spiral mixing structure of the reaction channel has a length a2 of 11 mm, a width b2 of 0.5 mm, and a height c2 of 2.9 mm, and is twisted 180°; the number of spiral mixing structures N2 is 6; the spacing L m The dimensions are 0.5mm, and they are arranged alternately in pairs at 90° intervals. The support structure for the cooling channel has a length a3 of 5.1mm, a width b3 of 0.5mm, and a height c3 of 3mm. The support structures are located on the XZ and YZ planes, respectively, and form angles of 150° with the Y-axis and X-axis. The spacing between structures on the same plane is L. n The thickness is 34mm; the number of support structures N3 is 34, and they are arranged in pairs at 120° to each other about the mixing channel.

[0031] According to such Figure 3 As shown, the boundary conditions are set as follows: 1. Material composition: Inlet-1: glycerol 100%, Inlet-2: mixed acid 23.03%, nitric acid 1.01%, sulfuric acid 73.96%, water 2%; 2. Inlet velocity: Inlet-1: 0.0033 m / s, Inlet-2: 0.079 m / s, Inlet-A: 0.44 m / s; 3. Outlet pressure: atmospheric pressure (0 MPa); 4. Inlet temperature: Inlet-1 = Inlet-2 = Inlet-A = -20℃; The calculated temperature distribution (a) and nitroglycerin mass fraction distribution (b) contour plots of the nitration reaction are shown below. Figure 3 As shown.

[0032] Example 2: Parallel scale-up of microfluidic field device in glycerol nitration

[0033] like Figure 5 As shown, a scale-up of the microreactor with 12 parallel inlets was performed. After multiple optimizations of the cooling structure, the flow rates at the glycerol inlet (Inlet-1) were determined to be 0.22 mL / min, the mixed acid inlet (Inlet-2) flow rate to be 5.44 mL / min, and the combined flow rate of the two cooling water inlets (Inlet-A and Inlet-B) to be 330 mL / min. The initial temperature of all materials was -5°C. The calculated single-inlet nitroglycerin production capacity was 0.042 kg / h, therefore, at least 12 inlets were connected in parallel, achieving a production capacity of 0.5 kg / h.

[0034] Inlet (volume flow rate):

[0035] 1. Glycerin single-channel flow rate: 0.22 mL / min; total flow rate: 2.68 mL / min (12 channels);

[0036] 2. Sulfuric acid single-channel flow rate: 4.61 mL / min; total flow rate: 55.30 mL / min (12 channels);

[0037] 3. Nitric acid single-channel flow rate: 0.64 mL / min; total flow rate: 7.64 mL / min (12 channels);

[0038] 4. Coolant flow rate per channel: 330 mL / min (sum of flow rates at both cooling inlets), total flow rate: 3960 mL / min (12 channels);

[0039] Outlet (volume flow rate):

[0040] 1. Single outlet flow rate of nitration mixture: 5.72 mL / min, total flow rate: 68.61 mL / min (12 outlets);

[0041] 2. Volume percentage of trinitroglycerin: 7.58%

[0042] 3. Volume percentage of waste acid / water (nitric acid, sulfuric acid, water, etc.), and volume percentage of each component: Sulfuric acid 77.46%, nitric acid 1.14%, water 6.35%, nitrifying agent 7.47%.

[0043] 4. Coolant single-channel flow rate: 330 mL / min; total flow rate: 3960 mL / min (12 channels);

[0044] like Figure 6 As shown, the flow rate of the single-channel material (glycerol and mixed acid) is set to 1.8 times the flow rate of the single-channel material. Considering that the temperature may rise after increasing the flow rate, the flow rate of the single-channel coolant is adjusted to 1.5 times the flow rate of the single-channel coolant, and the initial temperature of all materials is adjusted to -15℃.

[0045] Inlet (volume flow rate):

[0046] 1. Glycerin single-channel flow rate: 0.40 mL / min; total flow rate: 3.2 mL / min (8 channels);

[0047] 2. Sulfuric acid single-channel flow rate: 8.30 mL / min; total flow rate: 66.37 mL / min (8 channels);

[0048] 3. Nitric acid single-channel flow rate: 1.15 mL / min; total flow rate: 9.16 mL / min (8 channels);

[0049] 4. Coolant single-channel flow rate: 495 mL / min (sum of flow rates from two cooling inlets), total flow rate: 3960 mL / min (8 channels);

[0050] Outlet (volume flow rate):

[0051] 1. Single outlet flow rate of nitration mixture: 10.29 mL / min, total flow rate: 82.31 mL / min (8 outlets)

[0052] 2. Volume percentage of trinitroglycerin: 7.58%

[0053] 3. Volume percentage of waste acid / water (nitric acid, sulfuric acid, water, etc.), and volume percentage of each component: Sulfuric acid 77.46%, nitric acid 1.14%, water 6.35%, nitrifying agent 7.47%.

[0054] 4. Coolant single-channel flow rate: 495 mL / min (sum of flow rates from two cooling inlets), total flow rate: 3960 mL / min (8 channels);

[0055] like Figure 7 As shown, the flow rate of the single-channel material (glycerol and mixed acid) is set to 3.5 times the single-channel material flow rate. Considering the potential temperature rise after increasing the flow rate, the single-channel coolant flow rate is adjusted to twice the single-channel coolant flow rate, and the initial temperature of all materials is adjusted to -20℃. The calculated single-channel nitroglycerin production capacity is 0.15 kg / h, therefore, four channels are connected in parallel, achieving a production capacity of 0.60 kg / h.

[0056] Inlet (volume flow rate):

[0057] 1. Glycerin single-channel flow rate: 0.78 mL / min; total flow rate: 3.13 mL / min (4 channels);

[0058] 2. Sulfuric acid single-channel flow rate: 16.13 mL / min; total flow rate: 66.37 mL / min (4 channels);

[0059] 3. Nitric acid single-channel flow rate: 2.23 mL / min; total flow rate: 8.90 mL / min (4 channels);

[0060] 4. Coolant single-channel flow rate: 660 mL / min (sum of flow rates from two cooling inlets), total flow rate: 2640 mL / min (4 channels);

[0061] Outlet (volume flow rate):

[0062] 1. Single outlet flow rate of nitration mixture: 19.99 mL / min, total flow rate: 79.98 mL / min (4 outlets)

[0063] 2. Volume percentage of trinitroglycerin: 7.58%

[0064] 3. Volume percentage of waste acid / water (nitric acid, sulfuric acid, water, etc.), and volume percentage of each component: Sulfuric acid 77.46%, nitric acid 1.14%, water 6.35%, nitrifying agent 7.47%.

[0065] 4. Coolant single-channel flow rate is 660 mL / min (sum of flow rates from the two cooling inlets), and total flow rate is 2640 mL / min (4 channels).

Claims

1. A microfluidic field device for enhancing high-viscosity, strongly exothermic reactions, characterized in that, It comprises a sleeve (1) and a baffle and spiral mixing structure (2) in the reaction channel; all channels are square through holes, and the sleeve is formed by a cooling channel surrounding the entire reaction channel. The cooling channel has two inlets and one outlet, as well as a support structure. The reaction channel has two inlets and one outlet. The front part of the reaction channel is a baffle structure with a gap; the rear part is a spiral mixing structure. The reaction channel is built into the center of the cooling channel. Two streams of cooling water enter from two inlets and flow out from the outlet after passing through the channel. At least two streams of reaction fluid enter the mixing channel through the inlet channel for mixing, and the mixed fluid flows out through the outlet.

2. The microfluidic field device for enhancing high-viscosity, strongly exothermic reactions according to claim 1, characterized in that, The longitudinal length L0 of the cooling channel of the sleeve (1) is 280-320 mm, and the inner diameter D1 of the cooling channel is 5-10 mm; the longitudinal length L0 of the reaction channel is 280-320 mm, and the inner diameter D2 of the reaction channel is 1-4 mm.

3. The microfluidic field device for enhancing high-viscosity, strongly exothermic reactions according to claim 2, wherein the baffle structure of the reaction channel is a square baffle (length a1 is 2-8 mm, width b1 is 0.1-1 mm, height c1 is 1-6 mm) and is located in the XZ plane; the number of reaction channels N1 is 20-40; the baffle spacing L is 0.1-2 mm; and the distance L between the spiral mixing structure and the baffle structure is... s It is 0.1 to 2 mm.

4. The helical mixing structure of the reaction channel according to claim 3 (length a2 is 7-15 mm, width b2 is 0.1-2 mm, height c2 is 1-6 mm), and twisted by 90°-270°; the number of helical mixing structures N2 is 2-10; the spacing L m The diameter is 0.1 to 2 mm, and the two pairs are arranged alternately at 0 to 90 degrees.

5. The cooling channel according to claim 2, characterized in that, The interior includes a support structure; the support structure is square (length a3 is 3-8mm, width b3 is 0.1-2mm, height c3 is 1-6mm); the support structure is located in the XZ and YZ planes respectively, and forms angles of 0-180° with the Y-axis and X-axis, with the spacing L between structures on the same plane. n The thickness is 20-40mm; the number of support structures N3 is 20-40, and they are arranged in pairs with respect to the mixing channel at 0-180° to each other.

6. The application of the microfluidic field device according to any one of claims 1-5 in the following method systems: (1) Nitration of glycerol; or, (2) Parallel amplification of glycerol nitration.

7. The application according to claim 6, characterized in that, The fluid properties and boundary conditions of the glycerol nitration reaction system are as follows: mixed acid (98% concentrated sulfuric acid H2SO4 mass fraction 80-90%; 98% fuming nitric acid HNO3 mass fraction 10-20%), glycerol-nitric acid molar ratio 1:2-1:8, glycerol flow rate 0.0008-0.0015 (m / s), mixed acid flow rate 0.01-0.035 (m / s), inlet temperature and initialization temperature 1-5℃; cooling water main channel matching flow rate 0.02-0.2 (m / s), cooling water inlet flow rate 0.02-0.2 (m / s), cooling water temperature 1-5℃.

8. The application according to claim 6, characterized in that, The parallel scale-up application of glycerol nitration involves a 12-channel parallel amplification of the microreactor. Its fluid properties and boundary conditions are as follows: glycerol inlet Inlet-1 flow rate 0.05–0.5 mL / min, mixed acid inlet Inlet-2 flow rate 1–10 mL / min, and cooling water combined flow rate from the two inlets Inlet-A and Inlet-B 100–500 mL / min. Therefore, the initial material temperature is -10 to -1 °C.

9. The application according to claim 8, characterized in that, The parallel scale-up application of glycerol nitration involves a microreactor with eight parallel amplification channels. Its fluid properties and boundary conditions are as follows: the flow rate of each material (glycerol and mixed acid) is set at 1.8 times the flow rate of a single material channel; the flow rate at the glycerol inlet-1 is 0.09–0.9 mL / min; the flow rate at the mixed acid inlet-2 is 1.8–18 mL / min; the flow rate of the coolant in each channel is 1.5 times the flow rate of a single coolant channel; the combined flow rate of the two cooling water inlets, Inlet-A and Inlet-B, is 150–750 mL / min; and the initial temperature of all materials is -20 to -11 °C.

10. The application according to claim 8, characterized in that, The parallel scale-up application of glycerol nitration involves a four-channel parallel scale-up of the microreactor. The fluid properties and boundary conditions are as follows: the flow rate of each material (glycerol and mixed acid) is set to 3.5 times the flow rate of a single material; the flow rate at the glycerol inlet-1 is 0.175–1.75 mL / min; the flow rate at the mixed acid inlet-2 is 3.5–35 mL / min; the flow rate of the coolant in each channel is twice the flow rate of a single coolant; the combined flow rate of the two cooling water inlets, Inlet-A and Inlet-B, is 200–1000 mL / min; and the initial temperature of all materials is adjusted to -25–-16°C.

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