Dynamic experimental analysis method and device based on calibration type flow reaction calorimetry
By employing a calibrated flow reaction calorimetry method and calculating the reaction rate constant using thermal conversion rate, the problems of slow temperature control and complex mechanical structure in traditional reactors are solved. This enables efficient and safe kinetic and thermodynamic analysis, and is applicable to the safety and process optimization of chemical reactions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-21
- Publication Date
- 2026-04-03
AI Technical Summary
Traditional batch reactors suffer from large temperature overshoot and slow control speed in fast and highly exothermic chemical reactions. Furthermore, traditional flow dynamics analysis methods are inefficient, rely on complex mechanical structures and component detection equipment, and pose safety risks.
A kinetic experimental method based on calibrated flow reaction calorimetry is adopted. By changing the temperature conditions under a fixed flow rate and recording the temperature data of the reaction pipeline, the reaction rate constant is calculated using the thermal conversion rate. This simplifies the experimental platform structure and avoids additional component detection equipment and complex mechanical structures.
It improves the safety and efficiency of the reaction process, reduces reagent consumption, simplifies experimental equipment, enables kinetic and thermodynamic analysis under continuous flow conditions, and is suitable for risk assessment and process optimization of chemical reactions.
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Figure CN121784069A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fine chemical industry and reaction heat measurement and kinetic measurement. Specifically, it relates to a kinetic experimental analysis method and apparatus based on the calorimetric analysis of flow reaction, which is applicable to the measurement of kinetic parameters of flow reaction process. Background Technology
[0002] The kinetics and thermodynamics of chemical reactions can be used to determine optimal reaction conditions and improve reaction process control, serving as crucial parameters for process optimization and safety assessment in modern chemical industries. Currently, the main tools for kinetic calculations in laboratories are component detection devices such as spectrometers, primarily equipped with traditional batch reactors, requiring multiple experiments under various temperature conditions. Furthermore, batch reactors have large reaction volumes, leading to problems such as large temperature overshoot and slow control speed, posing certain safety risks for some fast-reacting, high-exothermic chemical reactions.
[0003] Continuous flow reaction technology can reduce reaction volume, thereby improving the mass and heat transfer efficiency of the reactor, reducing reagent consumption, increasing experimental efficiency, and lowering the risk of the reaction process. For kinetic analysis under flow conditions, traditional component detection-based methods require multiple adjustments of flow rate and temperature, resulting in low experimental efficiency. Other methods include incorporating pipeline design to circulate the reaction mixture within the pipeline, enabling multiple samplings within a single experiment; or adjusting flow rate and temperature within a single experiment to obtain the concentration distribution over time and temperature, thus improving experimental efficiency. However, both of these methods rely on complex mechanical structures.
[0004] By using flow reaction calorimetry and replacing component data with thermal conversion rate for calculations, on the one hand, there is no need to use additional component detection equipment, which simplifies the structure of the experimental platform; on the other hand, a set of experiments under different temperature conditions can yield thermodynamic and kinetic calculation results, reducing experimental steps and improving experimental efficiency. Summary of the Invention
[0005] To address the shortcomings of the existing technologies, this invention proposes a kinetic experimental analysis method and apparatus based on calibrated flow reaction calorimetry. This method requires neither additional component detection equipment nor complex mechanical structures, making it a highly efficient experimental analysis scheme while also improving the safety of the reaction process.
[0006] The kinetic experimental analysis method based on calibrated flow reaction calorimetry of the present invention includes:
[0007] Experimental section: Under a fixed flow rate, the reactants were pumped into the reaction pipeline through a preheating pipeline and a micro mixer. The calibration heater at the end of the reaction pipeline was turned on, causing the temperature of the reaction mixture to change before and after flowing through the heater.
[0008] Then, the temperature conditions during the experiment were changed multiple times, and the temperature data at different locations in the reaction pipeline were recorded by temperature sensor after the reaction system stabilized in each experiment.
[0009] Analysis Section: The above experimental section conducted multiple experiments under different temperature conditions, obtaining temperature data at different locations in the reaction pipeline under different temperature conditions. Calorimetric analysis was performed on the experimental data under each temperature condition to obtain the total heat release and heat conversion rate along the pipeline. The reaction rate constant under each temperature condition was calculated using nonlinear fitting. The calculated reaction rate constants under different temperature conditions were linearly fitted to obtain the kinetic parameters of the reaction process.
[0010] Further explanation of the calorimetric analysis of experimental data under each temperature condition in the analysis section specifically refers to: firstly, calculating the overall heat transfer coefficient of the reaction pipeline based on the heat balance equation in the pipeline when the calibrated heater is turned on:
[0011] P = Cp·m·DT + U·A·(T) r -T)
[0012] In the formula, P represents the heater power (unit: W), and Cp represents the specific heat capacity of the reaction mixture (unit: J·kg). -1 ·K -1 ), m represents mass flow rate (unit: kg·s) -1 ΔT represents the temperature difference of the reaction mixture after passing through the heater (unit: K), and A represents the inner wall area of the heating section of the reaction pipeline (unit: m²). 2 ), T r T represents the equivalent sample temperature of the heating section of the reaction pipeline (unit: K), T represents the constant temperature water bath temperature (unit: K), and U represents the overall heat transfer coefficient of the reaction pipeline (unit: W·m). -2 ·K -1 );
[0013] Next, based on the heat balance equation in the pipeline during the reaction, the total heat release and heat conversion rate along the pipeline are calculated. The reaction pipeline is then divided into segments, and the heat balance in segment i of the reaction pipeline during the reaction is as follows:
[0014]
[0015] In the formula Q r,i The reaction of a unit mass mixture within segment i is exothermic (unit: J·kg). -1 ), ΔT i A represents the temperature change of the reaction mixture within segment i (in K). i Represents the inner wall area of segment i (unit: m²) 2 ), T r,iRepresents the equivalent sample temperature (unit: K) within segment i;
[0016] Furthermore, the analysis section specifically refers to obtaining the kinetic parameters of the reaction process by using the heat conversion rate calculated through calorimetry to perform nonlinear fitting to calculate the reaction rate constant.
[0017]
[0018] In the formula: k is the reaction rate constant, R con (exp) is the actual heat conversion rate calculated based on experimental data, R con (sim) is the simulated heat conversion rate calculated based on the material conservation in the pipeline;
[0019] For the reaction rate constant under different temperature conditions, according to the transformation of the Arrhenius equation:
[0020]
[0021] The kinetic parameters are calculated using linear fitting, where k0 is the pre-factor (unit is the same as the reaction rate constant), and E is the activation energy (unit: J·mol). -1 R is the molar gas constant (unit: J·mol). -1 ·K -1 ).
[0022] To achieve the above method, the present invention also provides a kinetic experimental apparatus based on calibrated flow reaction calorimetry, including a reaction pipeline, a calibration heater, and multiple reactant channels;
[0023] The multi-channel reactant enters the reaction pipeline through a micro mixer, and flows out of the reaction pipeline after the reaction is completed. It then flows through the calibration heater and the back pressure valve in sequence, and the reaction products are collected through the liquid tail drain.
[0024] The reaction pipeline is equipped with a temperature sensor for monitoring the temperature of the reaction process;
[0025] The calibration heater is equipped with temperature sensors for monitoring the temperature before and after the heater.
[0026] Furthermore, each of the multiple reactant channels includes a reagent bottle, a sample pump, and a preheating line. The reactants are stored in the reagent bottle and enter the micromixer through the sample pump.
[0027] Furthermore, the reaction pipeline and micromixer are placed in a constant temperature bath to keep the ambient temperature of the reaction process constant.
[0028] Furthermore, a pressure sensor is installed between the calibration heater and the back pressure valve to monitor the reaction pressure.
[0029] The beneficial effects of this invention are:
[0030] 1. From the perspective of experimental safety, the reaction volume of a flow reactor is smaller, and the liquid holding volume is only a fraction of that of a traditional batch reactor. This can significantly reduce the use of reagents, save raw materials, and improve experimental safety. At the same time, the flow reactor has a larger specific surface area and has better heat exchange efficiency than a traditional batch reactor. The excellent mass and heat transfer performance can effectively shorten the reaction time, improve production efficiency, facilitate the control of production conditions, and enhance experimental safety.
[0031] 2. In terms of improving experimental efficiency, based on the thermal balance relationship within the pipeline during the reaction, the relationship between heat conversion rate and residence time is derived, and the reaction rate constant is calculated accordingly. This avoids the need to adjust the flow rate to obtain the relationship between conversion rate and residence time in traditional flow dynamics analysis methods, and eliminates the need for additional component detection equipment, thus simplifying the structure of the experimental platform and improving experimental efficiency.
[0032] 3. This invention can obtain the kinetics and thermodynamics of chemical reactions, and can be applied to risk assessment, process optimization and other aspects of chemical reactions under continuous flow conditions.
[0033] In summary, this invention eliminates the need for complex circuits and mechanical structures, overcoming the problem of requiring additional component detection equipment in traditional kinetic analysis methods, thus improving experimental efficiency. At the same time, by reducing the reaction volume, it enhances the safety of the experimental process. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of the structure of a continuous flow reaction experimental platform. Detailed Implementation
[0035] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.
[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and comprehensive understanding of the disclosure of the present invention.
[0037] This embodiment further illustrates the dynamics calculation method described in this invention.
[0038] Suppose a chemical reaction follows a second-order rate equation, and its reaction equation is as follows (1):
[0039] X+Y→Z(1)
[0040] In the formula, X is the first reactant, Y is the second reactant, and Z is the product. The reaction rate equation for this reaction, expressed in terms of the concentration of reactant X, is as follows (2):
[0041]
[0042] In the formula C X Let C be the concentration of reactant X. Y The concentration of reactant Y is given.
[0043] like Figure 1 As shown, during the experiment, reactant X was stored in the first reagent bottle 1 and entered the micromixer 3 through the first injection pump 2. Reactant Y entered the micromixer through the second injection pump. The two reactants were mixed evenly in the micromixer and then entered the reaction pipeline 4. Temperature sensors 5 were arranged at different positions in the reaction pipeline. After the reaction was completed, the product flowed out of the reaction pipeline and passed sequentially through the calibration heater 6, pressure sensor 7, and back pressure valve 8 before being collected through the liquid tail drain 9.
[0044] During the experiment, the micromixer, reaction pipeline and calibration heater were placed in a constant temperature water bath 10. The host computer 11 was used to monitor the reaction temperature, heater temperature, reaction pressure, constant temperature bath temperature and sample flow rate.
[0045] Based on the above experimental platform, the process of this embodiment is as follows:
[0046] Experimental section: Set the constant temperature bath temperature T1, sample pump flow rates F1 and F2, and pipeline heater power P, as follows. Figure 1 As shown, temperature sensors were placed at different locations in the reaction pipeline in the experimental platform. After the system stabilized, the temperature measurement results of the temperature sensors were recorded.
[0047] Then, the temperature of the constant temperature bath was changed to T2 to T4 for the experiment.
[0048] Analysis section: such as Figure 1 As shown, the experimental platform includes a calibration heater. After the calibration heater is turned on during the experiment, the temperature of the reaction mixture before and after flowing through the heater changes. The heat balance in the pipeline is expressed as:
[0049] P=Cp·m·ΔT r,j +U j ·A·(T r,j -T j (3)
[0050] In the formula, P represents the heater power, Cp represents the specific heat capacity of the reaction mixture, m represents the mass flow rate, and ΔT... r,j T represents the temperature difference of the reaction mixture after it flows through the heater in experiment j, A represents the inner wall area of the heating section of the reaction pipe, and T represents the temperature difference of the reaction mixture after it flows through the heater in experiment j. r,j T represents the equivalent sample temperature in the heating section of the reaction pipeline in experiment j. j This represents the constant temperature bath temperature set for experiment j. The heat transfer coefficient U of experiment j can be calculated according to equation (3). j ;
[0051] like Figure 1 As shown, multiple temperature sensors were arranged along the flow path in the reaction pipeline. The above experimental section conducted multiple experiments under different temperature conditions. After the reaction system stabilized in each experiment, temperature data was collected at different locations in the reaction pipeline using the temperature sensors. The temperature distribution in the reaction pipeline for each group of experiments was obtained through interpolation (the position of the temperature sensors in the pipeline should be adjusted appropriately for different types of chemical reactions). The interpolated temperature distribution was segmented, and the heat balance relationship within each temperature segment during the reaction is as follows:
[0052]
[0053] In the formula Q r,j,i The reaction of a unit mass mixture within experimental segment i is exothermic, ΔT j,i For the temperature change of the reaction mixture within segment i of experiment j, A i T represents the area of the inner wall of segment i. r,j,i T represents the equivalent sample temperature within segment i of experiment j. j This indicates the temperature of the constant temperature bath set in experiment j;
[0054] The total exothermic reaction Q is obtained by summing the heat from all sections of the reaction pipeline. r,j :
[0055]
[0056] The heat conversion rate R along the reactor pipeline is obtained by summing the heat released in stages and comparing it with the total heat released. con,j (exp):
[0057]
[0058] Given the flow rate, the heat conversion rate R along the reactor pipeline is... con,j (exp) can be converted into the heat conversion rate for different residence times.
[0059] If the concentration of reactant X is expressed using thermal conversion rate, then equation (2) can be transformed into equation (8):
[0060]
[0061] The experimental section conducted multiple experiments under different temperature conditions. For each experiment, a reaction rate constant was calculated. The relationship between the reaction rate constant and temperature is a variation of the Arrhenius equation:
[0062]
[0063] In the formula, k0 refers to the prefactor, E is the activation energy, and R is the molar gas constant;
[0064] For multiple sets of experimental results under different temperature conditions, lnk and 1 / T are fitted according to the form of equation (10) to obtain the intercept and slope, and then the dynamic parameters are obtained.
[0065] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Those skilled in the art can make various modifications and variations to the present invention according to actual circumstances. Any modifications, substitutions, and improvements made within the principles of the present invention should be included within the scope of the invention.
Claims
1. A kinetic experimental analysis method based on calibrated flow reaction calorimetry, characterized in that: Experimental Section: Under a fixed flow rate, the reactants were pumped into the reaction pipeline via a preheating line and a micro mixer; the calibration heater at the end of the reaction pipeline was turned on, causing the temperature of the reaction mixture to change before and after flowing through the heater; then the temperature conditions during the experiment were changed multiple times, and the temperature data at different locations in the reaction pipeline were recorded by a temperature sensor after the reaction system stabilized in each experiment; Analysis Section: The above experimental section conducted multiple experiments under different temperature conditions, obtaining temperature data at different locations in the reaction pipeline under different temperature conditions; calorimetric analysis was performed on the experimental data under each temperature condition to obtain the total heat release and heat conversion rate along the pipeline; the reaction rate constant under each temperature condition was calculated using nonlinear fitting; and the calculated reaction rate constants under different temperature conditions were linearly fitted to obtain the kinetic parameters of the reaction process.
2. The kinetic experimental analysis method based on calibrated flow reaction calorimetry according to claim 1, characterized in that: The analysis section performs calorimetric analysis on the experimental data under each temperature condition, specifically: First, calculate the overall heat transfer coefficient of the reaction pipeline based on the heat balance equation in the pipeline when the calibration heater is turned on. Next, the total heat release and heat conversion rate along the pipeline are calculated based on the heat balance equation in the pipeline when the reaction occurs.
3. The kinetic experimental analysis method based on calibrated flow reaction calorimetry according to claim 1, characterized in that: The analysis section specifically obtains the kinetic parameters of the reaction process by: using the heat conversion rate calculated by calorimetry to perform nonlinear fitting to calculate the reaction rate constant. In the formula: k is the reaction rate constant, R con (exp) is the actual heat conversion rate calculated based on experimental data, R con (sim) is the simulated heat conversion rate calculated based on the material conservation in the pipeline; For the reaction rate constant under different temperature conditions, the kinetic parameters are calculated by linear fitting based on the Arrhenius equation.
4. A kinetic experimental apparatus based on calibrated flow-reaction calorimetry, used to implement the method according to any one of claims 1-3, characterized in that: This includes reaction tubing, calibration heaters, and multiple reactant channels; The multi-channel reactant enters the reaction pipeline through a micro mixer, and flows out of the reaction pipeline after the reaction is completed. It then flows through the calibration heater and the back pressure valve in sequence, and the reaction products are collected through the liquid tail drain. The reaction pipeline is equipped with a temperature sensor for monitoring the temperature of the reaction process; The calibration heater is equipped with temperature sensors for monitoring the temperature before and after the heater.
5. A kinetic experimental apparatus based on calibrated flow reaction calorimetry according to claim 4, characterized in that: Each of the multiple reactant channels includes a reagent bottle and a sample pump. The reactants are stored in the reagent bottle and enter the micromixer through the sample pump.
6. A kinetic experimental apparatus based on calibrated flow reaction calorimetry according to claim 5, characterized in that: The reaction pipeline and micromixer are placed in a constant temperature bath to keep the ambient temperature of the reaction process constant.
7. A kinetic experimental apparatus based on calibrated flow reaction calorimetry according to claim 6, characterized in that: A pressure sensor is also installed between the calibration heater and the back pressure valve to monitor the reaction pressure.