Self-reaction substance drying process safety evaluation and grading method based on thermal analysis kinetics

Abstract

The invention discloses a self-reaction substance drying process safety assessment and classification method based on thermal analysis kinetics. The method comprises the following steps: performing a multi-heating-rate programmed heating test on a self-reaction substance under a closed condition by adopting DSC to obtain an exothermic initial temperature, a peak temperature and a specific exothermic quantity, constructing a thermal decomposition kinetic model based on the obtained data, and solving kinetic parameters such as apparent activation energy and pre-exponential factors; combining an energy conservation equation and a thermal explosion theory, predicting a self-accelerated decomposition temperature SADT under an adiabatic condition TD24 and a given filling and heat dissipation condition, determining a temperature safety threshold value of a drying process according to the SADT, and dividing a working condition safety interval; further introducing three dimensionless safety factors including a temperature safety margin, a time safety margin and a thermal explosion margin, constructing a comprehensive risk index, and carrying out risk grade division on the drying working condition. The method provided by the invention has the advantages of low sample consumption, simple test conditions and standardized calculation process, can quantitatively evaluate the safety drying temperature upper limit of different self-reaction substances and under different process conditions, and provides a reliable basis for drying process design and safety control of the self-reaction substances.

Description

Technical Field

[0001] This invention belongs to the field of safety technology for hazardous chemicals and energetic materials, specifically relating to a safety assessment and classification method for drying processes of self-reacting substances based on thermal analysis kinetics. Background Technology

[0002] Self-reactive materials possess the characteristic of undergoing accelerated self-decomposition under external stimuli such as heat, friction, and collision. They are highly susceptible to thermal runaway during production and post-processing (e.g., drying, dehumidification, and heating). Particularly during the drying process, due to factors such as material accumulation, limited heat dissipation, and uneven temperature distribution, irreversible accelerated self-decomposition reactions may occur within the self-reactive materials even before a significant external temperature rise is reached, leading to thermal runaway accidents.

[0003] Existing standards such as the UN Recommendations on the Transport of Dangerous Goods (Model Regulations), ASTM E1981 ARC (Test Method for Adiabatic Thermal Stability), N / T 3078.1-2012 (Guideline for Evaluation of Thermal Stability of Chemicals Part 1: Accelerated Calorimeter Method), and GB / T 13464-92 (Test Methods for Thermal Analysis of the Thermal Stability of Substances) provide SADT and TMR standards. ad Test methods for thermal safety parameters. However, the existing technology has the following shortcomings: (1) The above methods focus on the thermal hazard classification and storage and transportation safety of the material itself, and lack a clear method for how to quantitatively convert thermal analysis and kinetic parameters into the upper limit of the safe drying temperature under specific process conditions; (2) A systematic criterion coupling "thermal analysis kinetics + heat transfer process + process time + equipment loading structure" has not yet been established, and it is difficult to directly use it for temperature setting under actual drying process conditions; (3) The drying temperature in industrial sites is usually determined by experience or by introducing a large safety margin, and lacks a multi-index, quantifiable and reproducible safety assessment process.

[0004] Therefore, there is an urgent need for a method to determine the safe threshold temperature for drying self-reactive substances based on thermal analysis kinetics, adiabatic hazard criteria, and thermal explosion theory. This method should not only provide a clear upper limit for the safe temperature but also conduct multi-index risk assessment and classification based on actual operating conditions, providing a quantitative decision-making basis for the design and scale-up of self-reactive substance drying processes. Summary of the Invention

[0005] The purpose of this invention is to provide a safety assessment and classification method for drying processes of self-reactive substances based on thermal analysis kinetics. This method obtains thermal decomposition parameters of the thermal decomposition behavior through closed-loop DSC, constructs a multi-stage kinetic model of the self-reactive substance, and combines thermal explosion theory with the adiabatic hazard criterion (TMR). ad / T D24This allows for the quantitative determination of the upper limit of safe temperature in the drying process and the establishment of an engineered safety zoning and early warning mechanism. It is applicable to the thermal safety analysis and process control of explosives, sensitive chemicals, and self-accelerating thermal substances (SADTs) during the drying, dehumidification, and post-treatment processes.

[0006] The technical solution to achieve the purpose of this invention is as follows:

[0007] A safety assessment and classification method for self-reactive substance drying processes based on thermal analysis kinetics includes the following steps:

[0008] S1. Determine the self-reactive substance to be evaluated and the proposed drying process conditions, measure the moisture content of the self-reactive substance, and obtain the density ρ and specific heat capacity C of the self-reactive substance. p The thermal conductivity k was determined, and the structural form of the drying equipment was recorded to obtain the stacking thickness L, material loading, and heat exchange conditions with the external environment.

[0009] S2. In a sealed crucible, use differential scanning calorimetry (DSC) to perform dynamic temperature-programmed thermal decomposition tests on the self-reacting substance at at least four different heating rates, and obtain the DSC curve, exothermic onset temperature T0, and exothermic peak temperature T of the self-reacting substance. p , , specific heat release Q;

[0010] S3. Based on the DSC test data obtained in S2, a thermal decomposition kinetic model of the self-reacting substance is established using the model fitting method to obtain the kinetic parameters of the self-reacting substance.

[0011] S4. Under the adiabatic assumption, based on the thermal decomposition kinetic model established in S3, the temperature-time curve T(t) is obtained by numerical integration and iterative solution of the thermal equilibrium differential equation, and the time to reach the maximum reaction rate TMR is determined. ad Obtain TMR ad =T corresponding to 24h D24 ;

[0012] S5. Substitute the kinetic parameters obtained in S3 into the thermal explosion criterion equation, and combine the material loading, thermal conductivity k and external heat exchange conditions obtained in S1 to calculate the minimum ambient temperature of the self-accelerated decomposition state through numerical simulation, and obtain the self-accelerated decomposition temperature SADT.

[0013] S6. Calculate the safe temperature threshold T for the drying process of the self-reacting substance according to formula (1). safe : (1)

[0014] Where T0 is the exothermic onset temperature measured by DSC, SADT is the self-accelerating decomposition temperature obtained by S5, and ΔT0 and ΔTs and ΔT 24 These are for T0, SADT, and T respectively. D24 The set temperature safety margin;

[0015] S7. The proposed drying process temperature T OP With T safe Comparison, when T OP ≤T safe When T is used to determine that the drying process temperature is within a safe range; OP >T safe It was determined that there was a risk of thermal runaway in the drying process temperature.

[0016] S8, Based on temperature safety threshold T safe The proposed drying process temperature T OP The proposed drying time t d And the thermal explosion criterion parameters, respectively, calculate the temperature safety margin coefficient M according to formulas (2) to (4). T Time safety margin factor M t Thermal explosion margin factor M δ And according to formula (5), a weighted combination of temperature safety margin, time safety margin and thermal explosion margin is constructed to obtain the comprehensive risk index R. The risk level of the working condition is assessed based on the comprehensive risk index R.

[0017] (2)

[0018] (3)

[0019] Among them, TMR(T) OP ) for in T OP Under the conditions, the adiabatic thermal equilibrium equation is numerically integrated based on the S3 kinetic model to obtain the corresponding time to reach the maximum reaction rate.

[0020] (4)

[0021] Wherein, δ(T) OP () is the result calculated based on S5 at T OP Dimensionless parameters under certain conditions; thermal explosion margin coefficient M δ For δ(T) OP ) and critical value δ cr The ratio;

[0022] (5)

[0023] in , , These are the weighting coefficients.

[0024] Furthermore, the self-reactive substance includes one or more of the following: explosives, energetic materials, self-reactive monomers, organic peroxides, and oxidizing and reducing agent systems that readily accelerate self-decomposition. In a specific embodiment of the present invention, 1,1-diamino-2,2-dinitroethylene (FOX-7) is used as an example.

[0025] Furthermore, in S3, the thermal decomposition kinetic model is an n-order reaction model or an autocatalytic model; the kinetic parameters include the pre-exponential factor A, the apparent activation energy Ea, and the reaction order n.

[0026] Furthermore, S4 specifically involves: under adiabatic assumptions, based on the thermal decomposition kinetic model established in S3, solving the thermal equilibrium differential equation through numerical integration to simulate the temperature-time evolution of the system at different initial temperatures, obtaining the temperature-time curve T(t), and determining the time to reach the maximum reaction rate (TMR) through iterative calculations. ad =Temperature T over 24 hours D24 The differential equation for thermal equilibrium is:

[0027] (6)

[0028] in, For density, For specific heat capacity, To measure the amount of heat released, Let be the weight of the contribution of the i-th step reaction to the total heat release. Let i be the pre-exponential factor corresponding to step i. Let R be the activation energy corresponding to step i, R be the gas constant, and T be the ambient temperature. Let be the reaction mechanism function for step i.

[0029] Furthermore, S5 specifically refers to the thermal explosion criterion equation:

[0030] (7)

[0031] in For the dimensionless parameter under ambient temperature T; The critical Frank-Kamenetskii number depends on the packaging geometry, and L is the stacking thickness; Specific heat release; A is the pre-exponential factor; Ea is the activation energy; R is the gas constant; Density; Specific heat capacity; Thermal conductivity; The ambient temperature.

[0032] Furthermore, in S6, ΔT0, based on the engineering safety margin of the initial DSC decomposition, is 40℃~50℃; ΔTs According to the international standard (UN TDG), the margin for SADT is 20~30℃; ΔT 24 The time margin for considering adiabatic risk is 10℃~20℃; by analyzing ΔT0 and ΔT s and ΔT 24 Taking the minimum value ensures that all thermal runaway pathways are eliminated.

[0033] Furthermore, S7 also includes: according to T OP SADT and temperature monitoring point settings are used to construct the following operating condition range:

[0034] Safe Zone: T OP ≤ T safe -10℃, Monitoring area: T safe -10℃ < T OP ≤ T safe Warning zone: T safe < T OP ≤ SADT, Danger Zone: T OP ≥ SADT.

[0035] Furthermore, in S8, the risk level classification rules are as follows:

[0036] R ≤ 0.5: Level I risk;

[0037] 0.5 < R ≤ 1.0: Level II risk;

[0038] 1.0 < R ≤ 2.0: Level III risk;

[0039] R > 2.0: Level IV risk.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] This invention, through the construction of multi-index safety margins and comprehensive risk indices, enables quantitative comparison and classification of operating conditions with different combinations of drying temperature, loading capacity, and stacking thickness, and plots a safe operating window for drying process temperature-loading conditions, providing a visual decision-making basis for process scale-up design and operation optimization. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the dynamic heat dissipation of the DSC in the FOX-7.

[0043] Figure 2 The results are the exothermic fitting results of the thermal decomposition kinetic model for FOX-7.

[0044] Figure 3 The results are the fitting results of the exothermic rate of the thermal decomposition kinetic model for FOX-7. Detailed Implementation

[0045] The present invention provides a method for safety assessment and classification of self-reactive substance drying processes based on thermal analysis kinetics, comprising the following steps:

[0046] S1. Determine the self-reactive substance to be evaluated and the proposed drying process conditions, measure the moisture content of the self-reactive substance, and obtain the density ρ and specific heat capacity C of the self-reactive substance. p The thermal conductivity k was determined, and the structural form of the drying equipment was recorded to obtain the stacking thickness L, material loading, and heat exchange conditions with the external environment.

[0047] S2. In a sealed crucible, use differential scanning calorimetry (DSC) to perform dynamic temperature-programmed thermal decomposition tests on the self-reacting substance at at least four different heating rates, and obtain the DSC curve, exothermic onset temperature T0, and exothermic peak temperature T of the self-reacting substance. p , , specific heat release Q;

[0048] S3. Based on the DSC test data obtained in S2, a thermal decomposition kinetic model of the self-reacting substance is established using the model fitting method to obtain the kinetic parameters of the self-reacting substance.

[0049] S4. Under the adiabatic assumption, based on the thermal decomposition kinetic model established in S3, the temperature-time curve T(t) is obtained by numerical integration and iterative solution of the thermal equilibrium differential equation, and the time to reach the maximum reaction rate TMR is determined. ad Obtain TMR ad =T corresponding to 24h D24 ;

[0050] S5. Substitute the kinetic parameters obtained in S3 into the thermal explosion criterion equation, and combine the material loading, thermal conductivity k and external heat exchange conditions obtained in S1 to calculate the minimum ambient temperature of the self-accelerated decomposition state through numerical simulation, and obtain the self-accelerated decomposition temperature SADT.

[0051] S6. Calculate the safe temperature threshold T for the drying process of the self-reacting substance according to formula (1). safe : (1)

[0052] Where T0 is the exothermic onset temperature measured by DSC, SADT is the self-accelerating decomposition temperature obtained by S5, and ΔT0 and ΔT s and ΔT 24 These are for T0, SADT, and T respectively. D24 The set temperature safety margin;

[0053] S7. The proposed drying process temperature T OP With T safe Comparison, when TOP ≤T safe When T is determined to be within a safe temperature range, drying operations can be carried out at that temperature; OP >T safe If the drying process temperature is deemed to pose a risk of thermal runaway, it is necessary to reduce the drying temperature and / or adjust the stacking conditions until the Td requirement is met. OP ≤T safe The criteria for determining the safe temperature threshold of the self-reacting substance drying process are thus established.

[0054] S8, Based on temperature safety threshold T safe The proposed drying process temperature T OP The proposed drying time t d And the thermal explosion criterion parameters, respectively, calculate the temperature safety margin coefficient M according to formulas (2) to (4). T Time safety margin factor M t Thermal explosion margin factor M δ And according to formula (5), a weighted combination of temperature safety margin, time safety margin and thermal explosion margin is constructed to obtain the comprehensive risk index R. The risk level of the working condition is assessed based on the comprehensive risk index R.

[0055] (2)

[0056] (3)

[0057] Among them, TMR(T) OP ) for in T OP Under the conditions, the adiabatic thermal equilibrium equation is numerically integrated based on the S3 kinetic model to obtain the corresponding time to reach the maximum reaction rate.

[0058] (4)

[0059] Wherein, δ(T) OP () is the result calculated based on S5 at T OP Dimensionless parameters under certain conditions; thermal explosion margin coefficient M δ For δ(T) OP ) and critical value δ cr The ratio;

[0060] (5)

[0061] in , , This is a weighting coefficient, which can be equal or adjusted according to the actual working conditions.

[0062] Furthermore, the self-reactive substance includes one or more of the following: explosives, energetic materials, self-reactive monomers, organic peroxides, and oxidizing and reducing agent systems that readily accelerate self-decomposition. In a specific embodiment of the present invention, 1,1-diamino-2,2-dinitroethylene (FOX-7) is used as an example.

[0063] Furthermore, in S3, the thermal decomposition kinetic model is an n-order reaction model or an autocatalytic model; the kinetic parameters include the pre-exponential factor A, the apparent activation energy Ea, and the reaction order n.

[0064] Furthermore, S4 specifically involves: under adiabatic assumptions, based on the thermal decomposition kinetic model established in S3, solving the thermal equilibrium differential equation through numerical integration to simulate the temperature-time evolution of the system at different initial temperatures, obtaining the temperature-time curve T(t), and determining the time to reach the maximum reaction rate (TMR) through iterative calculations. ad =Temperature T over 24 hours D24 The differential equation for thermal equilibrium is:

[0065] (6)

[0066] in, For density, For specific heat capacity, To measure the amount of heat released, Let be the weight of the contribution of the i-th step reaction to the total heat release. Let i be the pre-exponential factor corresponding to step i. Let R be the activation energy corresponding to step i, R be the gas constant, and T be the ambient temperature. Let be the reaction mechanism function for step i.

[0067] Furthermore, S5 specifically refers to the thermal explosion criterion equation:

[0068] (7)

[0069] in For the dimensionless parameter under ambient temperature T; The critical Frank-Kamenetskii number depends on the packaging geometry, and L is the stacking thickness; Specific heat release; A is the pre-exponential factor; Ea is the activation energy; R is the gas constant; Density; Specific heat capacity; : represents thermal conductivity; The ambient temperature.

[0070] Furthermore, in S6, ΔT0, based on the engineering safety margin of the initial DSC decomposition, is 40℃~50℃; ΔT sAccording to the international standard (UN TDG), the margin for SADT is 20~30℃; ΔT 24 The time margin for considering insulation risk is 10℃~20℃.

[0071] Furthermore, S7 also includes: According to T OP SADT and temperature monitoring point settings are used to construct the following operating condition range:

[0072] Safe Zone: T OP ≤ T safe -10℃, Monitoring area: T safe -10℃ < T OP ≤ T safe Warning zone: T safe < T OP ≤ SADT, Danger Zone: T OP ≥ SADT; when T OP When the temperature is within the safe zone, the drying process is considered to be within a safe range; when T... OP Upon entering the monitored area, activate enhanced monitoring or shorten the inspection cycle; when T OP Upon entering the warning zone, an alarm signal is issued, and control measures such as reducing heating power, decreasing loading, or enhancing ventilation and heat dissipation are implemented; when T OP When entering the danger zone, if the system is considered to be close to or has entered a state of self-accelerating decomposition, heating should be stopped immediately and emergency measures should be taken.

[0073] Furthermore, in S8, the temperature safety margin factor M T M represents the relative position of the current process temperature with respect to the initial decomposition temperature T0 and the auto-accelerated decomposition temperature SADT. T The larger the value, the greater the temperature margin; when t d Much smaller than TMR(T) OP When M t The relatively large value indicates that even under near-adiabatic conditions at this temperature, the system still has a significant time buffer margin during the drying time; when the thermal explosion margin coefficient M... δ When M > 1, it indicates that the current operating condition is still on the safe side of the thermal explosion critical state. δ The larger the value, the higher the safety margin.

[0074] Furthermore, in S8, the risk level classification rules are as follows:

[0075] R ≤ 0.5: Level I risk, safe operating conditions, can operate for a long time under normal monitoring conditions;

[0076] 0.5 < R ≤ 1.0: Level II risk, it is recommended to strengthen online monitoring or appropriately reduce the loading amount;

[0077] 1.0 < R ≤ 2.0: Level III risk, only suitable for short-term operation under strict monitoring and comprehensive safety measures;

[0078] R > 2.0: Level IV risk, unacceptable operating conditions, process temperature should be reduced and / or stack thickness and load should be decreased.

[0079] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0080] Example 1: Safety assessment and classification of the drying process for the self-reactive substance FOX-7

[0081] (1) Sample preparation

[0082] Determining the water content and specific heat capacity C of FOX-7 p The four physical properties, density ρ, thermal conductivity k, and the result are: water content 11%, specific heat capacity C p It is 1.54 kJ·kg -1 ·℃ -1 Density C p It is 1.71 g·cm -1 The thermal conductivity k is 0.25 W·m. -1 ·℃ -1 .

[0083] (2) DSC test

[0084] A high-pressure sealed crucible was used to prevent sublimation loss. DSC experiments were conducted in the sealed crucible at temperature rise rates of 0.3, 0.5, 1, and 1.5 K / min. The results are as follows: Figure 1 Record the exothermic onset temperature T0 and the exothermic peak temperature T. p The specific heat release is Q.

[0085] Table 1. DSC test results of FOX-7 with 11% water content at different temperature rise rates

[0086] (3) Construction of dynamic model

[0087] Based on the thermal decomposition parameters obtained from DSC experiments, a two-step continuous reaction kinetic model (autocatalytic reaction + autocatalytic reaction) was adopted, and the fitting results are as follows: Figure 2 and Figure 3 Obtain the pre-exponential factor A and activation energy E. a Kinetic parameters such as reaction order n.

[0088] Table 2. Kinetic parameters of water-bearing FOX-7

[0089] (4) Predicting T D24

[0090] The TMR is obtained by integrating the differential equation of adiabatic heat balance. ad -T curve, solving for T D24 The temperature was 189.06℃. D24 It is an international thermal safety criterion used to determine whether a substance poses a risk of self-acceleration within 24 hours.

[0091] (5) SADT numerical estimation

[0092] The material stacking conditions are set as shown in Table 3, and the loading amount is 25 kg.

[0093] Table 3 Physical properties of water-containing FOX-7

[0094] Combining the Frank-Kamenetskii thermal explosion theory, considering heat dissipation from packaging and heat generation from the reaction, the self-acceleration condition is solved:

[0095] (7)

[0096] in : Critical Frank-Kamenetskii number, which depends on the packaging geometry; L: Stacking thickness; Specific heat release; A: pre-exponential factor; Ea: activation energy; R: gas constant; :density; Specific heat capacity; Thermal conductivity; Ambient temperature. The minimum self-accelerating temperature (SADT) of the material under drying conditions was obtained using numerical iteration. Solving the Frank-Kamenetskii criterion yielded an SADT of 165℃.

[0097] (6) Solve for the temperature safety threshold T safe

[0098] The safe threshold temperature T for the drying process of the self-reacting substance is calculated according to formula (1). safe :

[0099] } (1)

[0100] }

[0101] =145℃

[0102] Right now =145℃.

[0103] (7) Establishment of safe zone

[0104] According to T OPSADT and temperature monitoring point settings are used to construct the following operating condition ranges and establish a safe drying temperature zone and early warning mechanism:

[0105] Safe Zone: T OP ≤ 132℃;

[0106] Monitoring area: 132℃ < T OP ≤ 145℃;

[0107] Warning zone: 145℃ < T OP ≤ 165℃;

[0108] Danger Zone: T OP ≥ 165℃.

[0109] It can be integrated into the automated temperature control system of drying equipment to achieve automatic early warning.

[0110] (8) Multi-indicator safety margin and risk level assessment

[0111] Assuming the drying process temperature T to be used OP =120℃, drying time t d =6 h, density ρ is 1.71 g·cm³ -1 The thermal conductivity k is 0.25 W·m. -1 ·℃ -1 Specific heat C P It is 1.54 kJ·kg -1 ·℃ -1 Given a buildup thickness L of 0.02 m, calculate the temperature safety margin factor. Time safety margin coefficient Thermal explosion margin coefficient Preset weights , , Each is 1 / 3, and the calculated comprehensive risk index R = 0.55 < 1, indicating that the operating conditions are safe and can be operated long-term under normal monitoring conditions. If R exceeds the preset upper limit, T can be reduced. OP Reduce the stacking thickness L or shorten the stacking time t d Adjust process parameters using methods such as [unspecified methods] until the target risk level is reached.

Claims

1. A safety assessment and classification method for self-reacting substance drying processes based on thermal analysis kinetics, characterized in that, Includes the following steps: S1. Determine the self-reactive substance to be evaluated and the proposed drying process conditions, measure the moisture content of the self-reactive substance, and obtain the density ρ and specific heat capacity C of the self-reactive substance. p The thermal conductivity k was determined, and the structural form of the drying equipment was recorded to obtain the stacking thickness L, material loading, and heat exchange conditions with the external environment. S2. In a sealed crucible, use differential scanning calorimetry (DSC) to perform dynamic temperature-programmed thermal decomposition tests on the self-reacting substance at at least four different heating rates, and obtain the DSC curve, exothermic onset temperature T0, and exothermic peak temperature T of the self-reacting substance. p , , specific heat release Q; S3. Based on the DSC test data obtained in S2, a thermal decomposition kinetic model of the self-reacting substance is established using the model fitting method to obtain the kinetic parameters of the self-reacting substance. S4. Under the adiabatic assumption, based on the thermal decomposition kinetic model established in S3, the temperature-time curve T(t) is obtained by numerical integration and iterative solution of the thermal equilibrium differential equation, and the time to reach the maximum reaction rate TMR is determined. ad Obtain TMR ad =T corresponding to 24h D24 ; S5. Substitute the kinetic parameters obtained in S3 into the thermal explosion criterion equation, and combine the material loading, thermal conductivity k and external heat exchange conditions obtained in S1 to calculate the minimum ambient temperature of the self-accelerated decomposition state through numerical simulation, and obtain the self-accelerated decomposition temperature SADT. S6. Calculate the safe temperature threshold T for the drying process of the self-reacting substance according to formula (1). safe : （1） Where T0 is the exothermic onset temperature measured by DSC, SADT is the self-accelerating decomposition temperature obtained by S5, and ΔT0 and ΔT s and ΔT 24 These are for T0, SADT, and T respectively. D24 The set temperature safety margin; S7. The proposed drying process temperature T OP With T safe Comparison, when T OP ≤T safe When T is used to determine that the drying process temperature is within a safe range; OP >T safe It was determined that there was a risk of thermal runaway in the drying process temperature. S8, Based on temperature safety threshold T safe The proposed drying process temperature T OP The proposed drying time t d And the thermal explosion criterion parameters, respectively, calculate the temperature safety margin coefficient M according to formulas (2) to (4). T Time safety margin factor M t Thermal explosion margin factor M δ And according to formula (5), a weighted combination of temperature safety margin, time safety margin and thermal explosion margin is constructed to obtain the comprehensive risk index R. The risk level of the working condition is assessed based on the comprehensive risk index R. （2） （3） Among them, TMR(T) OP ) for in T OP Under the conditions, the adiabatic thermal equilibrium equation is numerically integrated based on the S3 kinetic model to obtain the corresponding time to reach the maximum reaction rate. （4） Wherein, δ(T) OP () is the result calculated based on S5 at T OP Dimensionless parameters under certain conditions; thermal explosion margin coefficient M δ For δ(T) OP ) and critical value δ cr The ratio; （5） in , , These are the weighting coefficients.

2. The method for safety assessment and classification of self-reacting substance drying process according to claim 1, characterized in that, The self-reactive substance is selected from one or more of the following: explosives, energetic materials, self-reactive monomers, organic peroxides, and oxidizing and reducing agents that are prone to self-accelerated decomposition.

3. The method for safety assessment and classification of self-reacting substance drying process according to claim 1, characterized in that, The self-reactive substance is FOX-7.

4. The method for safety assessment and classification of self-reacting substance drying process according to claim 1, characterized in that, In S3, the thermal decomposition kinetic model is an n-order reaction model or an autocatalytic model; the kinetic parameters include the pre-exponential factor A, the apparent activation energy Ea, and the reaction order n.

5. The method for safety assessment and classification of self-reacting substance drying process according to claim 1, characterized in that, Specifically, S4 involves: under adiabatic assumptions, based on the thermal decomposition kinetic model established in S3, solving the thermal equilibrium differential equation through numerical integration to simulate the temperature-time evolution of the system at different initial temperatures, obtaining the temperature-time curve T(t), and determining the time to reach the maximum reaction rate (TMR) through iterative calculations. ad =Temperature T over 24 hours D24 The differential equation for thermal equilibrium is: （6） in, For density, For specific heat capacity, To measure the heat released, Let be the weight of the contribution of the i-th step reaction to the total heat release. Let i be the pre-exponential factor corresponding to step i. Let R be the activation energy corresponding to step i, R be the gas constant, and T be the ambient temperature. Let be the reaction mechanism function for step i.

6. The method for safety assessment and classification of self-reacting substance drying process according to claim 1, characterized in that, S5 specifically refers to the thermal explosion criterion equation: （7） in For the dimensionless parameter under ambient temperature T; The critical Frank-Kamenetskii number depends on the packaging geometry, and L is the stacking thickness; Specific heat release; A is the pre-exponential factor; Ea is the activation energy; R is the gas constant; Density; Specific heat capacity; Thermal conductivity; The ambient temperature.

7. The method for safety assessment and classification of self-reacting substance drying process according to claim 1, characterized in that, In S6, ΔT0 is 40℃~50℃; ΔT s 20~30℃; ΔT 24 The temperature range is 10℃ to 20℃.

8. The method for safety assessment and classification of self-reacting substance drying process according to claim 1, characterized in that, S7 also includes: According to T OP SADT and temperature monitoring point settings are configured to construct the following operating condition range: Safe Zone: T OP ≤ T safe -10℃, Monitoring area: T safe -10℃<T OP ≤ T safe Warning zone: T safe < T OP ≤SADT, Danger Zone: T OP ≥SADT.

9. The method for safety assessment and classification of self-reacting substance drying process according to claim 1, characterized in that, In S8, the risk level classification rule is: R≤0.5: Level I risk; 0.5 < R ≤ 1.0: Level II risk; 1.0 < R ≤ 2.0: Level III risk; R > 2.0: Level IV risk.

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