A distributed measurement method and device for content of cracking components of hydrocarbon fuel

Abstract

The application discloses a kind of distributed measurement methods for the content of hydrocarbon fuel cracking component: target material is pumped into reaction tube and heated to the target temperature required for thermal cracking;Real-time monitoring of relevant parameters;Real-time cooling and collecting the gas phase, liquid phase material of target material after thermal cracking;Online analysis of the component distribution of target material after thermal cracking, obtain the component distribution of target material after thermal cracking at different temperatures;Change pressure, continue the above steps to obtain the component distribution of target material after thermal cracking at different pressures;Based on the component distribution of target material after thermal cracking at different temperatures and different pressures, obtain the function of target material conversion rate and component content with temperature change respectively, and obtain the distribution of target material conversion rate and component content along the reaction tube respectively.The application also discloses a kind of using above-mentioned method device.The method and device realize the accurate measurement of distributed fuel conversion rate and component content.

Description

Technical Field

[0001] This invention relates to the fields of hydrocarbon fuel thermodynamics, thermodynamics, thermochemistry, and supercritical fluids, and specifically to a distributed measurement method and apparatus for the content of hydrocarbon fuel cracking components. Background Technology

[0002] Scramjet engines are the primary power components of hypersonic vehicles. The combined effects of fuel combustion heat release and aerodynamic heating during flight cause a rapid increase in engine surface temperature, posing a significant risk to the safe and stable operation of the vehicle. Active regenerative cooling technology, employing endothermic hydrocarbon fuels as the combustible coolant, is crucial for effectively cooling and thermally protecting critical engine components and ensuring safe vehicle operation. As the Mach number of hypersonic vehicles increases, the cooling demands on the engine continue to rise, requiring further cracking of hydrocarbon fuels to release more chemical heat sinks. However, the secondary reactions of hydrocarbon fuel cracking products generate a large amount of coking precursors. These precursors accumulate on the cooling channel walls, forming coke, which affects the heat transfer performance of the regenerative cooling system and, in severe cases, blocks the cooling channels, causing the regenerative cooling system to fail. Therefore, clarifying the degree of hydrocarbon fuel cracking and changes in fuel composition within the pipeline is of great significance for studying the flow state, convective heat transfer mechanism, mass transfer characteristics, and thermochemical reaction mechanism of hydrocarbon fuels.

[0003] Since the fuel pyrolysis process can be decomposed into an infinite number of continuous micro-reactions at different fuel conversion rates, Jiang Peixue et al. established a global differential reaction (DGR) model with variable stoichiometric coefficients using fluid dynamics simulations and successfully predicted the flow heat transfer process and pyrolysis reaction of n-decane. The DGR model determines the stoichiometric coefficients of each component based on its mass / molar fraction in the n-decane pyrolysis experiment and considers secondary reactions of some pyrolysis products. For n-decane pyrolysis experiments with fuel conversion rates below 24.2%, the model's prediction error for the mass fraction of pyrolysis products is less than 4.2% (Jiang P, Wang Y, Zhu Y. Differential Global Reaction Model with Variable Stoichiometric Coefficients for Thermal Cracking of n -Decane at SupercriticalPressures[J]. Energy & Fuels , 2019, 33, 7244-7256.).

[0004] Zhang Dingrui et al. conducted thermal cracking experiments on n-dodecane under supercritical pressure. Based on the cracking depth, the thermal cracking of n-dodecane was divided into three stages: primary cracking, secondary cracking, and deep cracking. For the primary cracking stage, where the fuel conversion rate is below 13%, a one-step global reaction kinetics model was constructed to establish the functional relationship between the mass fraction of major cracking products and the fuel conversion rate. For the secondary cracking stage, the thermal decomposition of alkanes and olefins, and the formation of monocyclic aromatics and cyclic olefins were further considered. Based on the component content of each cracking product in the primary and secondary cracking stages, a three-dimensional numerical model covering fuel flow heat transfer and thermal cracking reaction was established. The predicted values ​​of fuel outlet temperature, conversion rate, and cracking product distribution showed good agreement with the experimental results, verifying the reliability of the three-dimensional numerical model for the primary and secondary thermal cracking of n-dodecane (Zhang D, Hou L, Gao M. Experiment and Modeling on Thermal Cracking of n -Dodecane at Supercritical Pressure[J]. Energy & Fuels , 2018, 32, 12426-12434.).

[0005] Based on the thermal cracking mechanism of n-decane, Zhang Limei et al. established a high-precision model of the n-decane cracking reaction involving 16 substances and 26 reaction mechanisms. They further investigated the secondary reactions of n-decane at high conversion rates. In computational fluid dynamics (CFD) simulations, this model was more accurate than the global one-step reaction model for n-decane in predicting fuel conversion rate, temperature, and product distribution. This model can better reflect the changing trends of isobaric specific heat and convective heat transfer coefficient of the fluid (Zhang L, Yin R, Wang J. Numerical Investigations on the Molecular Reaction Model for Thermal Cracking of n -Decane at Supercritical Pressures[J]. ACS Omega , 2022, 7, 22351-22362.).

[0006] Ke Tian et al. optimized the RP-3 fuel pyrolytic model based on chemical reaction kinetics and the corresponding state principle. The optimized model includes 14 species and 6 reaction mechanisms. The model's calculation results in predicting fuel temperature distribution, species diffusion, thermophysical properties, fluid flow state, and coke deposition on the pipeline surface at high conversion rates almost overlap with existing simplified models, and the calculation time is reduced by 47.5% (Tian K, Tang Z, Wang J. Simplified Pyrolytic Model of RP-3 Fuel at High Conversion Rates and the Effects of Primary Reaction on the Regenerative Cooling Process[J]. Aerospace Science and Technology , 2022,129, 7853-7864.).

[0007] Chinese patent CN111122652A discloses a simplification method for a deep cracking model of hydrocarbon fuels. The method's first simplification is based on the ratio of the reaction rate of each sub-reaction to the main reaction rate, and the second simplification is based on replacing the simplified reaction groups with single components. This method can accurately predict behaviors such as fuel temperature distribution, component transport, flow field conditions, and coking on pipeline surfaces, and can significantly improve computational efficiency.

[0008] In summary, numerical calculations play a crucial role in fields such as thermochemical reactions and convective heat transfer. However, hydrocarbon fuel cracking typically involves a large number of product species and complex cracking kinetics. Current two-dimensional and three-dimensional numerical calculations only satisfy simplified fuel cracking models. However, these simplification methods only address errors in predicting fuel cracking parameters and fail to account for uncertainties in rate coefficients and the evolution of relevant parameters during the reaction process, thus affecting the reliability and rationality of the cracking model. Summary of the Invention

[0009] The purpose of this invention is to provide a distributed measurement method and apparatus for the content of hydrocarbon fuel cracking components, which realizes the accurate measurement of distributed fuel conversion rate and the content of each component.

[0010] This invention provides the following technical solution:

[0011] A distributed measurement method for the content of hydrocarbon fuel cracking components, the method comprising:

[0012] (1) Pump the target material into the reaction tube and apply a stable heat flux density to the reaction tube using a DC power supply so that the target material is heated to the target temperature required for thermal decomposition.

[0013] (2) Real-time monitoring of the inlet and outlet temperature changes of the target substance, the wall temperature of the reaction tube, and the system pressure at both ends of the reaction tube;

[0014] (3) Real-time cooling and collection of the gaseous and liquid phases of the target material after thermal pyrolysis;

[0015] (4) Gas chromatography and gas chromatography-mass spectrometry were used to analyze the component distribution of the target substance after thermal pyrolysis online, and the component distribution of the target substance after thermal pyrolysis at different temperatures was obtained;

[0016] (5) When the reaction tube is cooled to room temperature, change the pressure and continue the above steps (1)-(4) to obtain the component distribution of the target material after thermal decomposition under different pressures;

[0017] (6) Based on the component distribution data of the target material after thermal decomposition at different temperatures and pressures, the conversion rate of the target material and the content of each component as a function of temperature are obtained respectively, and the distribution of the conversion rate of the target material and the content of each component along the reaction tube is further obtained respectively.

[0018] To avoid the problems caused by the simplification of fuel species and cracking mechanisms in past numerical calculations and simulations of hydrocarbon fuel thermochemical reactions, which could not account for the uncertainty of rate coefficients in detailed mechanisms and the development of relevant parameters during the reaction process, this invention proposes a new method for measuring hydrocarbon fuel conversion rate and component content based on distributed flow calorimetry. The measurement objects include the conversion rate of the target substance, the change of component content with temperature, and the distribution of target substance conversion rate and component content along the reaction tube.

[0019] The technical concept of this invention is as follows: Based on the distributed flow calorimetry, this invention assumes that the fuel temperature is equal in each micro-element of the reaction tube and that the correlation between fuel pyrolysis and reaction time is negligible. It establishes a function of hydrocarbon fuel conversion rate and component content as a function of temperature. Through a pre-calibrated temperature-heat sink function, the temperature distribution of fuel along the reaction tube is obtained, and further, the distribution of target substance conversion rate and component content along the reaction tube is obtained. Thus, the intrinsic relationship between the target substance's position in the reaction tube, temperature, conversion rate, and component content under different pressures is established.

[0020] The measurement method provided by this invention is a distributed flow calorimetry.

[0021] In step (1), the target substance is selected from one or a combination of at least two of alkanes, alkenes, cycloalkanes, cycloolefins or aromatic hydrocarbons.

[0022] Further, in step (1), the flow rate of the target substance pumped into the reaction tube is 0.1-10 g / s or 1-1000 ml / s, the inner diameter of the reaction tube is 1-6 mm, the length of the reaction tube is 0.5-1.0 m, and the heat flux density applied to the target substance by the DC regulated power supply is 0-1×10⁻⁶ g / s. 6 W / m 2 The heating rate is 5-25 K / min, and the target temperature required for thermal decomposition is 773-1073 K.

[0023] Furthermore, in step (3), the gaseous phase of the target substance after thermal decomposition includes hydrogen, alkane compounds, olefin compounds, and alkyne compounds; the liquid phase product of the target substance after thermal decomposition includes alkane compounds, olefin compounds, cycloalkane compounds, cycloolefin compounds, and aromatic hydrocarbon compounds.

[0024] Furthermore, in step (6), the conversion rate of the target substance as a function of temperature is: α ( T The function of the content of each component changing with temperature is: M i ( T ); The reaction tubes were pre-divided n Each micro-element is used to determine the temperature distribution of the target substance along the reaction tube using a temperature-heat sink function. Assuming the target substance is isothermal within each micro-element and the correlation between thermal decomposition and reaction time is negligible, the distribution of the target substance conversion rate along the reaction tube is as follows: α -1 ( T The distribution of each component along the reaction tube is as follows: M i -1 ( T ).

[0025] Furthermore, the method also includes:

[0026] (7) Conduct an experiment to verify the accuracy of the conversion rate and component content of the target material along the reaction tube: change the length of the reaction tube, maintain the same flow heat transfer characteristics in each group, and continue steps (1)-(5) to obtain the fuel conversion rate and component distribution of the target material after thermal cracking under different tube length conditions.

[0027] Furthermore, the accuracy of the target material conversion rate and component content distribution along the reaction tube was verified by changing the length of the reaction tube while maintaining the same flow heat transfer characteristics in each group, and obtaining the fuel conversion rate and component distribution of the target material after thermal cracking under different tube length conditions.

[0028] Furthermore, the flow heat transfer characteristics of the same target material are that the heat flux density applied by the DC regulated power supply to each reaction tube is the same; under the same heat flux density conditions, x Temperature distribution on the wall of a 1 m reaction tube and temperature distribution of a 1 m reaction tube at 0 - x The wall temperature distribution error at point m is less than 1.0%.

[0029] Furthermore, the principle of the accuracy verification is based on the same heat flux density conditions. x The temperature and content distribution of gaseous and liquid phase substances at the outlet end of the 1 m reaction tube are considered as 1 m reaction tube in x Reference values ​​for the temperature and content distribution of gaseous and liquid phase substances at point m.

[0030] The present invention also provides a distributed measurement device for the above method, the measurement device comprising:

[0031] A high-pressure constant flow pump is used to stably pump the target substance to the reaction tube; a liquid flow meter is used to monitor the mass flow rate of the target substance and the mass flow rate of the liquid phase substance in real time; a gas flow meter is used to monitor the mass flow rate of the gas phase substance in real time; a DC regulated power supply is used to input a stable heat flux density into the reaction tube; the reaction tube is used for the thermal decomposition of the target substance; a thermocouple is used to monitor the fluid outlet temperature in real time; an infrared thermal imager is used to monitor the wall temperature of the reaction tube in real time; a pressure sensor is used to monitor the system pressure in real time; a back pressure valve is used to provide a stable system pressure; a condenser is used to rapidly cool the gaseous and liquid phases of the target substance after thermal decomposition; a gas-liquid separation tank is used to separate the gaseous and liquid phases of the target substance after thermal decomposition; a gas chromatograph and a gas chromatography-mass spectrometry system are used to analyze the composition of the gaseous and liquid phases of the target substance after thermal decomposition; and a waste gas and waste liquid recovery device is used to recover the decomposition gas and liquid of the target substance.

[0032] The industrial computer is used to execute steps (6) and (7).

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] (1) This invention uses experimental measurement methods to monitor the change trend of conversion rate and the evolution of gaseous and liquid phase substances during fuel pyrolysis, and takes into account the development state of related substances during the reaction process in detail. On this basis, the intrinsic relationship between position, temperature, conversion rate and content of each component is established, which improves the reliability and rationality of the pyrolysis model.

[0035] (2) This invention provides data support for the study of fuel flow heat transfer mechanism, chemical thermodynamic mechanism and chemical kinetic mechanism, and provides testing and evaluation methods for the development of new fuels. Attached Figure Description

[0036] Figure 1Flowchart for measuring distributed conversion rate and component content of hydrocarbon fuels;

[0037] Figure 2 This is a schematic diagram of the measuring device.

[0038] Figure 3 The content of each component in the liquid phase after n-decane cracking changes with temperature (3 MPa, 1 g / s).

[0039] Figure 4 The conversion rate of n-decane with temperature is given when the reaction tube length is 1 m (3 MPa, 1 g / s).

[0040] Figure 5 The content of n-decane cracking product (1-pentene) varies with temperature (3 MPa, 1 g / s).

[0041] Figure 6 The values ​​represent the reference values ​​for the conversion rate of n-decane along the reaction tube when the tube length is 0.5-1 m.

[0042] Figure 7 The conversion rate of n-decane with temperature under different reaction tube lengths (3 MPa, 1 g / s).

[0043] Figure 8 Comparison of experimental and reference values ​​for n-decane conversion along the path (3 MPa, 1 g / s).

[0044] Figure 9 Comparison of experimental and reference values ​​for the content of n-decane cracking product (1-pentene) (3 MPa, 1 g / s). Detailed Implementation

[0045] The following examples are intended to enable those skilled in the art to fully understand the present invention, but do not limit the invention in any way.

[0046] The flowchart of the distributed measurement method for fuel conversion rate and component content in the thermochemical process of hydrocarbon fuels provided by this invention is as follows: Figure 1 As shown, the structural schematic diagram of the measuring device is as follows: Figure 2 As shown, it includes a high-pressure constant flow pump, a liquid flow meter, a gas flow meter, a DC regulated power supply, a reaction tube, a thermocouple, an infrared thermal imager, a pressure sensor, a back pressure valve, a condenser, a gas-liquid separation storage tank, a gas chromatograph, a gas chromatograph-mass spectrometer, a waste gas and waste liquid recovery device, and an industrial control computer.

[0047] The method for distributed measurement of fuel conversion rate and component content in the thermochemical process of hydrocarbon fuels using the measuring device provided by the present invention includes:

[0048] (1) A high-pressure constant flow pump pumps the target material into the reaction tube; a DC power supply applies a stable heat flux density to the reaction tube so that the target material is heated to the target temperature required for thermal decomposition.

[0049] (2) Thermocouples monitor the temperature changes at the inlet and outlet of the target substance in real time; infrared thermal imagers monitor the wall temperature of the reaction tube in real time; and pressure sensors monitor the system pressure at both ends of the reaction tube in real time.

[0050] (3) The condenser tube cools the target substance after thermal pyrolysis in real time; the gas-liquid separation tank separates the gas phase and liquid phase substances; the gas flow meter and liquid flow meter monitor the flow rate of the gas phase and liquid phase substances in real time respectively.

[0051] (4) Gas chromatography is used to analyze the gas phase distribution of the target substance after thermal pyrolysis; gas chromatography-mass spectrometry is used to analyze the liquid phase distribution of the target substance after thermal pyrolysis.

[0052] (5) When the reaction tube is cooled to room temperature, the pressure is changed by the back pressure valve, and the above steps (1)-(4) are continued to obtain the component distribution of the target material after thermal decomposition under different pressures;

[0053] (6) Based on the component distribution data of the target substance after thermal pyrolysis at different temperatures and pressures detected by the gas chromatograph and gas chromatography-mass spectrometry, the industrial control computer obtains the function of the conversion rate of the target substance and the content of each component as a function of temperature, and further obtains the distribution of the conversion rate of the target substance and the content of each component along the reaction tube; and conducts an accuracy verification experiment on the distribution of the conversion rate of the target substance and the content of each component along the reaction tube.

[0054] Example 1

[0055] In this embodiment, n-decane was used as the target fluid. The n-decane was delivered to the reaction tube via a high-pressure constant flow pump at a mass flow rate of 1 g / s, a pressure of 3 MPa, and a reaction tube length of 1 m. The temperature was gradually increased from 298 K to 1073 K in 25 K increments. The heat flux density applied by the DC regulated power supply was recorded as the temperature was changed. The fuel inlet and outlet temperatures and system pressure were measured in real time during each heating step. When the fuel reached the initial pyrolysis temperature (773 K), the gaseous and liquid phases after pyrolysis were collected every 25 K. Gas chromatography-mass spectrometry was used to analyze the distribution of the liquid phase components online, obtaining the changes in the content of each component in the liquid phase after n-decane pyrolysis with temperature, such as... Figure 3 As shown.

[0056] The industrial control computer uses data on the conversion rate of n-decane and the content of each component as a function of temperature to obtain fitting functions for these parameters, as shown below. Figure 4 and Figure 5 As shown;

[0057] The hydrocarbon fuel conversion rate as a function of temperature is:

[0058] T When K ≤ 823, α ( T ) = 0

[0059] 823 K < T When K ≤ 900, α ( T = 2066.46 - 4.99 T +0.0031· T 2 (R=0.99)

[0060] 900 K < T When K ≤ 1023, α ( T = -8271.01 + 16.23 T -0.0079 T 2 (R=0.99)

[0061] The function of the content of each component changing with temperature is as follows: taking 1-pentene as an example.

[0062] M ( T = -5810.09 - 26.85 T -0.0463· T 2 -3.53·10 -5 · T 3 -1.00·10 -8 · T 4 (R=0.99).

[0063] In this embodiment, the reaction tube length was gradually shortened in 0.1 m increments, and n-decane cracking experiments were conducted in reaction tubes with lengths of 0.9, 0.8, 0.7, 0.6, and 0.5 m, respectively. Taking a tube length of 0.9 m as an example, the n-decane mass flow rate and pressure were maintained at the same level as when the reaction tube length was 1 m. During the experiment, the heat flux density applied by the DC regulated power supply remained consistent with that when the reaction tube length was 1 m. Under the same heat flux density conditions, each group... x Temperature distribution on the wall of a 1 m reaction tube and temperature distribution of a 1 m reaction tube at 0 - x The wall temperature distribution error at point m is less than 1.0%; the above conditions are used to ensure x Thermochemical reactions along a 1 m long tube and reaction tube at 0- xThe thermochemical reactions along the reaction tube at length m are similar. The reference values ​​for the conversion of n-decane along the reaction tube at a length of 0.5-1 m are as follows: Figure 6 As shown in the figure. The change in n-decane conversion rate with temperature under different reaction tube lengths is as follows. Figure 7 As shown.

[0064] The industrial control computer uses a fitting function of the n-decane conversion rate and the content of each component as a function of temperature, along with a pre-calibrated n-decane temperature-heat sink curve, to obtain the distributed conversion rate of n-decane and the content of each component (taking 1-pentene as an example). Figure 8 and Figure 9 As shown. Compared with the n-decane conversion rate and component content obtained from the verification experiment, the relative error of the n-decane distributed conversion rate is less than 5%, and the relative error of the n-decane distributed component content (taking 1-pentene as an example) is less than 2%.

Claims

1. A distributed measurement method for the content of hydrocarbon fuel cracking components, characterized in that, The distributed measurement method includes: (1) The target material is pumped into the reaction tube, and a stable heat flux density is applied to the reaction tube using a DC power supply to raise the temperature of the target material to the target temperature required for thermal decomposition; wherein, the flow rate of the target material pumped into the reaction tube is 0.1-10 g / s or 1-1000 ml / s; (2) Real-time monitoring of the inlet and outlet temperature changes of the target substance, the wall temperature of the reaction tube, and the system pressure at both ends of the reaction tube; (3) Real-time cooling and collection of the gaseous and liquid phases of the target material after thermal pyrolysis; (4) Gas chromatography and gas chromatography-mass spectrometry were used to analyze the component distribution of the target substance after thermal pyrolysis online, and the component distribution of the target substance after thermal pyrolysis at different temperatures was obtained; (5) When the reaction tube is cooled to room temperature, change the pressure and continue the above steps (1)-(4) to obtain the component distribution of the target material after thermal decomposition under different pressures; (6) Based on the component distribution of the target material after thermal decomposition at different temperatures and pressures, the functions of the conversion rate and component content of the target material with temperature are obtained respectively, and the distribution of the conversion rate and component content of the target material along the reaction tube is further obtained respectively. In step (6), the conversion rate of the target substance as a function of temperature is: α ( T The function of the content of each component changing with temperature is: M i ( T ); The reaction tubes were pre-divided into n Each micro-element is used to determine the temperature distribution of the target substance along the reaction tube using a temperature-heat sink function. Assuming the target substance is isothermal within each micro-element and the correlation between thermal decomposition and reaction time is negligible, the distribution of the target substance conversion rate along the reaction tube is as follows: α -1 ( T The distribution of each component along the reaction tube is as follows: M i -1 ( T ).

2. The distributed measurement method for hydrocarbon fuel cracking component content according to claim 1, characterized in that, In step (1), the target substance is selected from one or a combination of at least two of alkanes, alkenes, cycloalkanes, cycloolefins or aromatic hydrocarbons.

3. The distributed measurement method for hydrocarbon fuel cracking component content according to claim 1, in step (1), the inner diameter of the reaction tube is 1-6 mm, the length of the reaction tube is 0.5-1.0 m, and the heat flux density applied to the target material by the DC regulated power supply is 0-1×10⁻⁶ m. 6 W / m 2 The heating rate is 5-25 K / min, and the target temperature required for thermal decomposition is 773-1073 K.

4. According to the distributed measurement method for hydrocarbon fuel cracking component content as described in claim 1, in step (3), the gaseous phase of the target substance after thermal cracking includes hydrogen, alkane compounds, olefin compounds, and alkyne compounds; the liquid phase product of the target substance after thermal cracking includes alkane compounds, olefin compounds, cycloalkane compounds, cycloolefin compounds, and aromatic hydrocarbon compounds.

5. The distributed measurement method for hydrocarbon fuel cracking component content according to claim 1, characterized in that, The method includes: (7) Conduct an experiment to verify the accuracy of the conversion rate and component content of the target material along the reaction tube: change the length of the reaction tube, maintain the same flow heat transfer characteristics in each group, and continue steps (1)-(5) to obtain the fuel conversion rate and component distribution of the target material after thermal cracking under different tube length conditions.

6. The distributed measurement method for hydrocarbon fuel cracking component content according to claim 5, characterized in that, The target material exhibits the same flow and heat transfer characteristics, meaning that the heat flux density applied to each reaction tube by the DC regulated power supply is the same; under the same heat flux density conditions... x Temperature distribution on the wall of a 1 m reaction tube and temperature distribution of a 1 m reaction tube at 0 - x The wall temperature distribution error at point m is less than 1.0%.

7. The distributed measurement method for hydrocarbon fuel cracking component content according to claim 5, characterized in that, The principle of the accuracy verification is based on the same heat flux density conditions. x The temperature and content distribution of gaseous and liquid phase substances at the outlet end of the 1 m reaction tube are considered as 1 m reaction tube in x Reference values ​​for the temperature and content distribution of gaseous and liquid phase substances at point m.

8. A distributed measurement device employing the method of any one of claims 5-7, characterized in that, The measuring device includes: A high-pressure constant flow pump is used to stably pump the target substance to the reaction tube; a liquid flow meter is used to monitor the mass flow rate of the target substance and the liquid phase substance in real time; a gas flow meter is used to monitor the mass flow rate of the gas phase substance in real time; a DC regulated power supply is used to input a stable heat flux density to the reaction tube; the reaction tube is used for the thermal decomposition of the target substance; a thermocouple is used to monitor the fluid outlet temperature in real time; an infrared thermal imager is used to monitor the wall temperature of the reaction tube in real time; a pressure sensor is used to monitor the system pressure in real time; a back pressure valve is used to provide a stable system pressure; a condenser is used to rapidly cool the gaseous and liquid phases of the target substance after thermal decomposition; a gas-liquid separation tank is used to separate the gaseous and liquid phases of the target substance after thermal decomposition; a gas chromatograph and a gas chromatography-mass spectrometry system are used to analyze the composition of the gaseous and liquid phases of the target substance after thermal decomposition; and a waste gas and waste liquid recovery device is used to recover the decomposition gas and liquid of the target substance. An industrial computer is used to execute steps (6) and (7).

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