Method for determining critical safety diameter of emulsion drop of liquid energetic material synthesis reaction conveying pipeline

Abstract

The invention discloses a method for determining the critical safety diameter of an emulsion drop of a liquid energetic material synthesis reaction conveying pipeline, which comprises the following steps of: curing and heating a sampled emulsion, determining pyrolysis kinetic parameters of the detected emulsion, constructing a heat production and heat transfer heat insulation system model of a mixed solution of an acid ester emulsion and the emulsion drop by utilizing Comsol, and determining the critical safety diameter of the emulsion drop of the liquid energetic material synthesis reaction conveying pipeline. Calculating a temperature rise change rule of the mixed liquid heat insulation system under different emulsion droplet sizes, determining a function relationship between the emulsion droplet particle size and the temperature rise of the mixed liquid heat insulation system, and deriving to obtain the critical safety diameter of the emulsion droplet; the method comprises the following steps: adsorbing emulsified liquid by using a porous particle material, testing whether the emulsified liquid explodes due to collision and friction of emulsified liquid with different pore diameters at different rates in an impact tank-piston device to obtain the relationship among the movement rate of emulsified liquid drops, the particle size of the emulsified liquid drops and the explosion risk, and determining the explosion risk of the emulsified liquid drops under a specific conveying speed condition according to the relationship. The liquid energetic material is used for synthesizing the optimal size of emulsified liquid drops in a reaction mixed solution.

Description

Technical Field

[0001] The invention relates to a method for determining the safe size of liquid energetic material emulsion droplets, in particular to a method for determining the critical safe diameter of emulsion droplets in a liquid energetic material synthesis reaction delivery pipeline. Background Art

[0002] Liquid energetic materials are widely used in military and civilian fields. However, in the production process, the purity of raw materials is difficult to control and the synthesis reaction speed is fast. The generated emulsified products are easily affected by the environmental conditions. The emulsified products are dispersed and suspended in the acid ester emulsion in the form of droplets. During pipeline transportation, the emulsified droplets will collide with each other. As the transportation distance and transportation time increase, they will gradually condense and settle, and begin to autocatalytically react to store heat and heat up. Once a certain critical safety threshold is exceeded, the autocatalytic acceleration will occur, and the temperature of the reaction system will rise sharply, which will cause an explosion. Therefore, studying the critical safety diameter of emulsified droplets in the liquid energetic material synthesis reaction transportation pipeline is a hot issue in this industry.

[0003] In response to the problem of friction and collision explosion of energetic materials, some domestic scholars have conducted some research and discussion on it, and developed a friction sensitivity and impact sensitivity test method for energetic materials. In the invention patent with patent number 202010705274.6, a friction sensitivity test device and method are disclosed. The comprehensive application of the sample loading system, explosion chamber, pendulum mechanism, temperature and humidity control system, pressure loading system and frame is used to establish a comprehensive testing environment. According to the friction reaction of explosives under different temperature, humidity, speed and pressure conditions, the friction sensitivity data of explosives are obtained; in the invention patent with patent number 202010925198.X, a method and device for characterizing the friction sensitivity of insensitive single explosives are disclosed. The test sample is spread flat on the friction plate, the test sample is vertically pressed with a friction column, a fixed load is applied as the loading pressure, and the test calculation method of the established lifting method is used. According to the test sample during the friction process, the friction sensitivity data is calculated. Ignition conditions are measured to obtain the friction sensitivity value of insensitive single-element explosives; in the invention patent with patent number 202310727384.6, a friction sensitivity test device under thermal coupling is disclosed. Through the integrated application of a temperature control module, an electrostatic conductive workbench, a friction sensitivity device and a data acquisition and processing module, the friction sensitivity data is obtained according to the friction reaction of the energetic material under thermal coupling; in the utility model patent with patent number 202221397684.X, a friction sensitivity tester is disclosed. Through the integrated application of a working base, a functional frame, a friction component, a striking component, a support frame and a swing component, an automated testing process is used to obtain the friction sensitivity of the measured material according to the physical reaction of the measured material during the friction process.

[0004] From the above, it can be seen that the current research results of friction and impact sensitivity test devices and methods of energetic materials are remarkable, but the research and test objects are mainly concentrated on solid and formed energetic materials. For many energetic materials, the synthesis reaction is completed under liquid phase conditions, and the emulsion droplets formed in the reaction process already have flammable and explosive properties. The size of the droplets determines the possibility of this property being stimulated. On the other hand, since the synthesis of energetic materials is currently completed in a synthesizer, the synthesized emulsion disperses and moves in the acid ester emulsion, the collision and friction between the droplets and the pipeline, the container wall, and the droplets are aggravated, and the emulsion droplets are more easily stimulated. Therefore, determining the critical safety diameter of the emulsion droplets in the conveying pipeline is a hot issue that needs to be solved in this industry. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for determining the critical safety diameter of emulsified droplets in the liquid energetic material synthesis reaction conveying pipeline. The method can design emulsified droplets with the best safety size according to the speed and distance differences in the conveying process links in the synthesis process of different liquid energetic materials, provide guidance for the optimization of the process production line, and solve the problem of the intensification of autocatalytic reaction caused by collision, coagulation and sedimentation during the emulsified droplet conveying process, which further induces heat storage and temperature rise explosion of the system.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline, comprising the following specific steps:

[0008] A. First, sample a number of acid ester emulsions and emulsified liquids from the outlet of the separation unit pipeline of the liquid energetic material production line, measure the heat transfer coefficients of the acid ester emulsions and emulsified liquid droplets using the transient hot line method, and place them in a cooling system below 0°C for solidification and storage for standby use;

[0009] B. Take a sample of the mixture of acid ester emulsion and emulsion from the delivery outlet of the synthesis reaction, and put it into a cooling system below 0°C for solidification and storage for standby use;

[0010] C. Take a number of samples of the solidified emulsion and put them into a differential scanning calorimeter. Heat the temperature from 0°C to 370°C. Repeat the test 5 times at different heating rates, K1, K2, K3, K4, and K5. Record the heat flow value H of the emulsion during each continuous heating process. Determine the melting point T1 of the emulsion and the peak heat flow H of the exothermic peak. max , average exothermic peak heat flow value H ave , integrate the exothermic peak in the heat flow value-time curve to obtain the heat release ΔH of the emulsion and the decomposition exothermic curve;

[0011] D. Obtain the emulsion conversion rate α-time t curve by calculating the decomposition exothermic curve ÷ the exothermic heat in step B, and correspond it with the temperature T-time t recorded by the differential scanning calorimeter to determine the conversion rate α-temperature T relationship; and perform the first-order derivative to obtain the reaction rate dα / dt-temperature T;

[0012] E. According to the reaction rate dα / dt-temperature T and conversion rate α-temperature T curves, the Friedman method is used to determine the activation energy E, pre-exponential factor A and decomposition mechanism function model f(α) corresponding to different conversion rates α;

[0013] F. Calculate the self-accelerating decomposition temperature T according to the Semenov ideal model NR , the calculation equation is:

[0014]

[0015] Where M Di The diameter of the emulsion droplet is D i When, the mass of a drop of emulsion, g; U represents the heat transfer coefficient of the emulsion, J / (cm 2 ·K·s); S is the surface area of ​​a drop of emulsion, cm 2 ; R represents the gas molar constant, 8.314 J / (mol·L).

[0016] G. Based on the calculated self-accelerating decomposition temperature and decomposition mechanism function of the emulsion droplets, Comsol is used to construct an adiabatic system model for heat generation and heat transfer of the mixture of acid ester emulsion and emulsion droplets, and the temperature rise variation law of the adiabatic system of the mixed liquid under different emulsion droplet sizes is calculated. The functional relationship T(D) between the emulsion droplet size and the temperature rise of the adiabatic system of the mixed liquid is determined, and the critical safety diameter D' of the emulsion droplets is obtained by derivation;

[0017] H. Melt the solidified emulsion in a water bath at 20-25°C, and select porous particle materials with different pore sizes to adsorb the emulsion within the emulsion droplet diameter range of D'±0.1D' according to the obtained critical safety diameter of the emulsion droplet D';

[0018] I. When the porous granular material reaches the adsorption standard, a porous granular material containing different emulsion droplet particle sizes is formed, and the number of porous granular materials containing emulsion droplets under the same pore size is 300 to 600, which are reserved;

[0019] J. Under the same pore size, 5-10 porous granular materials are arranged at the bottom of the impact tank-piston device, and a porous granular material with the same pore size containing emulsion droplets is arranged on the piston head. The piston is pushed into the tank at different speeds (v1, v2, v3, v4, v5) to cause collision and friction between the porous granular materials containing emulsion droplets;

[0020] K. Record whether an explosion occurs in each test, and obtain the relationship between the movement rate of the emulsion droplets, the particle size of the emulsion droplets and the explosion risk, so as to determine the optimal size of the emulsion droplets in the liquid energetic material synthesis reaction mixture under specific conveying speed conditions.

[0021] Furthermore, the cooling system below 0°C in step A includes: an ice-salt bath, dry ice ethanol or liquid nitrogen cooling system.

[0022] Furthermore, the cooling system below 0°C in step B includes: an ice-salt bath, dry ice ethanol or liquid nitrogen cooling system.

[0023] Furthermore, the heating rates K1, K2, K3, K4, and K5 in step C do not exceed 10° C. / min.

[0024] Furthermore, in step H, the number of pore sizes selected for the porous particle materials with different pore sizes is not less than 5 groups.

[0025] Furthermore, the porous particle material in step H includes molecular sieves made of aluminosilicate and aluminophosphate.

[0026] Furthermore, the adsorption standards in step I include: saturated adsorption for 24 hours, long-period adsorption for 8-16 hours, and short-period adsorption for 4-10 minutes.

[0027] Furthermore, in step J, no less than 10 groups of porous granular material collision-friction tests are performed at the same rate.

[0028] Furthermore, in step J, the movement speeds v1, v2, v3, v4, and v5 of the piston do not exceed 25 m / s.

[0029] Compared with the prior art, the present invention first solidifies and heats the sampled emulsion to determine the pyrolysis kinetic parameters of the tested emulsion, including: the heat flow value of the emulsion, the melting point of the emulsion, the exothermic peak heat flow, and the self-accelerating decomposition temperature. Comsol is used to construct an adiabatic system model for heat generation and heat transfer of a mixed liquid of an acid ester emulsion and emulsion droplets, and the temperature rise variation law of the mixed liquid adiabatic system under different emulsion droplet sizes is calculated. The functional relationship T(D) between the emulsion droplet particle size and the temperature rise of the mixed liquid adiabatic system is determined, and the relationship is derived to obtain the critical safety diameter D' of the emulsion droplets. Then, the emulsion is adsorbed by a porous granular material, and the collision and friction of emulsions with different pore sizes in the range of D'±0.1D' at different speeds are tested in an impact tank-piston device to determine whether the emulsion will explode. The relationship between the movement rate of the emulsion droplets, the particle size of the emulsion droplets and the explosion risk is obtained, and the optimal size of the emulsion droplets in the liquid energetic material synthesis reaction mixture under specific conveying speed conditions is determined accordingly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1It is the overall flow chart of the present invention.

[0031] Figure 2 It is a decomposition heat flow curve of a solidified emulsion of a certain energetic material in the present invention.

[0032] Figure 3 It is a relationship diagram between the conversion rate α and the temperature T of a certain energetic material in the present invention.

[0033] Figure 4 It is a relationship diagram of reaction rate dα / dt-temperature T of a certain energetic material in the present invention.

[0034] Figure 5 It is a functional relationship diagram of the emulsion droplet size and the temperature rise of the mixed liquid insulation system in the present invention.

[0035] Figure 6 It is a diagram of the impact tank-piston device in the present invention.

[0036] Figure 7 It is a relationship diagram between the movement rate of emulsion droplets, the particle size of emulsion droplets and the explosion risk in the present invention.

[0037] Figure 8 It is a simulation verification relationship diagram between the movement rate of the emulsion droplets, the particle size of the emulsion droplets and the temperature rise of the system in the present invention.

[0038] In the figure, 1-impact tank body; 2-piston head of porous granular material containing emulsified droplets; 3-porous granular material containing emulsified droplets at the bottom; 4-piston; 5-eccentric wheel; 6-driving device. DETAILED DESCRIPTION

[0039] The present invention will be further described below.

[0040] like Figures 1 to 5 As shown, the specific steps of the present invention are:

[0041] A. First, sample 200 mL of acid ester emulsion and emulsified liquid from the outlet of the separation unit pipeline of the liquid energetic material production line, measure the heat transfer coefficient of the acid ester emulsion and emulsified liquid droplets using the transient hot line method, and put them into a cooling system below 0°C for solidification and storage for standby use;

[0042] B. Take 200 mL of the mixture of acid ester emulsion and emulsion from the synthetic reaction delivery outlet, and put it into a cooling system below 0°C for solidification and storage for standby use;

[0043] C. Take 20 mg of the solidified emulsion sample and put it into the differential scanning calorimeter. Start heating from 0℃ to 370℃. Repeat the test 5 times at different heating rates, 1℃ / min, 2℃ / min, 4℃ / min, 8℃ / min, 10℃ / min, respectively. Record the heat flow value H of the emulsion during each continuous heating process. Determine the melting point T1 of the emulsion and the peak heat flow H of the exothermic peak. max , average exothermic peak heat flow value H ave , integrate the exothermic peak in the heat flow value-time curve to obtain the heat release ΔH of the emulsion and the decomposition exothermic curve, such as Figure 2 As shown in Table 1;

[0044] Table 1 Thermal decomposition characteristic values ​​of certain azo energetic materials

[0045]

[0046] D. The emulsion conversion rate α-time t curve is obtained by dividing the decomposition heat release curve in step B by the heat release, and the conversion rate α-temperature T relationship is determined by comparing it with the temperature T-time t recorded by the differential scanning calorimeter, such as Figure 3 As shown; and take the first-order derivative to get the reaction rate dα / dt-temperature T, as Figure 4 As shown;

[0047] E. According to the reaction rate dα / dt-temperature T and conversion rate α-temperature T curves, the Friedman method is used to determine the activation energy E, pre-exponential factor A and decomposition mechanism function model f(α) corresponding to different conversion rates α, as shown in Table 2.

[0048] Table 2 Activation energy E, pre-exponential factor A and decomposition mechanism function model f(α) of a certain azo energetic material

[0049]

[0050] F. Calculate the self-accelerating decomposition temperature T according to the Semenov ideal model NR , the calculation equation is:

[0051]

[0052] Where M Di The diameter of the emulsion droplet is D i When, the mass of a drop of emulsion, g; U represents the heat transfer coefficient of the emulsion, J / (cm 2 ·K·s); S is the surface area of ​​a drop of emulsion, cm 2 ; R represents the gas molar constant, 8.314 J / (mol·L).

[0053] The calculation results are shown in Table 2:

[0054] Table 2 Self-accelerating decomposition temperature of azo energetic materials

[0055]

[0056] G. Based on the calculated self-accelerating decomposition temperature and decomposition mechanism function of the emulsion droplets, Comsol is used to construct an adiabatic system model for heat generation and heat transfer of the mixture of acid ester emulsion and emulsion droplets, as shown below:

[0057]

[0058] Where Q represents the heat generated, J; m represents the mass of the droplet, g; ρ represents the density of the emulsion, g / cm 3 ; c represents the specific heat capacity of the liquid, J / (g·℃); T represents the liquid temperature, ℃; t represents the time; u represents the liquid flow rate, m / s; k represents the thermal conductivity of the liquid, W / (m·℃).

[0059] Calculate the temperature rise variation law of the mixed liquid adiabatic system under different emulsion droplet sizes, determine the functional relationship T(D) between the emulsion droplet size and the temperature rise of the mixed liquid adiabatic system, and perform differentiation to obtain the critical safety diameter D' of the emulsion droplet, such as Figure 5 As shown;

[0060] H. Melt the solidified emulsion in a water bath at 20-25°C, and select porous particle materials with different pore sizes to adsorb the emulsion in the range of [0.9D', 1.1D'] according to the critical safety diameter D' of the emulsion droplets obtained;

[0061] I. After the porous granular material reaches the adsorption standard, a porous granular material containing different emulsion droplet particle sizes is formed, and the number of porous granular materials containing emulsion droplets under the same pore size is 300, which are reserved;

[0062] J. Under the same pore size, take 5 porous granular materials and arrange them at the bottom of the impact tank-piston device, and at the same time arrange a porous granular material with the same pore size containing emulsion droplets on the piston head, such as Figure 6 As shown, the piston is pushed into the tank at different speeds (1m / s, 2m / s, 5m / s, 10m / s, 15m / s) to cause collision and friction between the porous granular materials containing the emulsion droplets;

[0063] K. Record whether an explosion occurs in each test, and obtain the relationship between the emulsion droplet movement velocity v, the emulsion droplet particle size D and the explosion risk P, such as Figure 7 As shown, the optimal size D" of the emulsion droplets in the liquid energetic material synthesis reaction mixture under specific conveying speed conditions is determined.

[0064] L. Construct a physical model of emulsion droplets and mixed liquids with a particle size range of [0.95D”, 1.05D”] in Comsol, and use the adiabatic system model of heat generation and heat transfer to calculate the temperature rise law of the system at different movement rates, such as Figure 8 As shown, the accuracy of the actual test results is verified.

Claims

1. A method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline, characterized in that: The specific steps are: A. First, sample the acid ester emulsion and emulsified liquid from the outlet of the separation unit pipeline of the liquid energetic material production line, measure the heat transfer coefficient of the acid ester emulsion and the emulsified liquid droplets using the transient hot line method, and put them into a cooling system below 0°C for solidification and storage for standby use; B. Take a sample of the mixture of acid ester emulsion and emulsion from the delivery outlet of the synthesis reaction, and put it into a cooling system below 0°C for solidification and storage for standby use; C. Take a sample of the solidified emulsion and put it into a differential scanning calorimeter. Heat it from 0℃ to 370℃. Repeat the test 5 times at different heating rates. The heating rates are K1, K2, K3, K4, and K5 respectively. Record the heat flow value H of the emulsion during each continuous heating process. Determine the melting point T1 of the emulsion and the peak heat flow H of the exothermic peak. max , average exothermic peak heat flow value H ave , integrate the exothermic peak in the heat flow value-time curve to obtain the heat release ΔH of the emulsion and the decomposition exothermic curve; D. Obtain the emulsion conversion rate α-time t curve by calculating the decomposition exothermic curve ÷ the exothermic heat in step B, and correspond it with the temperature T-time t recorded by the differential scanning calorimeter to determine the conversion rate α-temperature T relationship; and perform the first-order derivative to obtain the reaction rate dα / dt-temperature T; E. According to the reaction rate dα / dt-temperature T and conversion rate α-temperature T curves, the Friedman method is used to determine the activation energy E, pre-exponential factor A and decomposition mechanism function model f(α) corresponding to different conversion rates α; F. Calculate the self-accelerating decomposition temperature T according to the Semenov ideal model NR , the calculation equation is: In the formula, The diameter of the emulsion droplet is D i When, the mass of a drop of emulsion, g; U represents the heat transfer coefficient of the emulsion, J / (cm 2 ·K·s); S is the surface area of ​​a drop of emulsion, cm 2 ; R represents the gas molar constant, 8.314 J / (mol·L); G. Based on the calculated self-accelerating decomposition temperature and decomposition mechanism function of the emulsion droplets, Comsol is used to construct an adiabatic system model for heat generation and heat transfer of the mixture of acid ester emulsion and emulsion droplets, and the temperature rise variation law of the adiabatic system of the mixed liquid under different emulsion droplet sizes is calculated. The functional relationship T(D) between the emulsion droplet size and the temperature rise of the adiabatic system of the mixed liquid is determined, and the critical safety diameter D' of the emulsion droplets is obtained by derivation; H. Melt the solidified emulsion in a water bath at 20-25°C, and select porous particle materials with different pore sizes to adsorb the emulsion within the emulsion droplet diameter range of D'±0.1D' according to the obtained critical safety diameter of the emulsion droplet D'; I. When the porous granular material reaches the adsorption standard, a porous granular material containing different emulsion droplet particle sizes is formed, and the number of porous granular materials containing emulsion droplets under the same pore size is 300 to 600, which are reserved; J. Under the same pore size, 5-10 porous granular materials are arranged at the bottom of the impact tank-piston device, and a porous granular material with the same pore size containing emulsified droplets is arranged on the piston head. The piston is pushed into the tank at different speeds v1, v2, v3, v4, and v5 to cause collision and friction between the porous granular materials containing emulsified droplets; K. Record whether an explosion occurs in each test, and obtain the relationship between the movement rate of the emulsion droplets, the particle size of the emulsion droplets and the explosion risk, so as to determine the optimal size of the emulsion droplets in the liquid energetic material synthesis reaction mixture under specific conveying speed conditions.

2. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: The cooling system below 0° C. in step A includes: an ice-salt bath, dry ice ethanol or liquid nitrogen cooling system.

3. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: The cooling system below 0° C. in step B includes: an ice-salt bath, dry ice ethanol or liquid nitrogen cooling system.

4. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: The heating rates K1, K2, K3, K4 and K5 in step C do not exceed 10°C / min.

5. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: Comsol is used to construct an adiabatic system model for heat generation and heat transfer of a mixture of acid ester emulsion and emulsified droplets, as shown below: Where Q represents the heat generated, J; m represents the mass of the droplet, g; ρ represents the density of the emulsion, g / cm 3 ; c represents the specific heat capacity of the liquid, J / (g·℃); T represents the liquid temperature, ℃; t represents the time; u represents the liquid flow rate, m / s; k represents the thermal conductivity of the liquid, W / (m·℃).

6. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: In step H, the number of pore sizes selected for the porous particle materials with different pore sizes is not less than 5 groups.

7. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: The porous particle material in step H includes molecular sieves made of aluminosilicate and aluminophosphate.

8. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: The adsorption standards in step I include: saturated adsorption for 24 hours, long-cycle adsorption for 8-16 hours, and short-cycle adsorption for 4-10 minutes.

9. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: In step J, at least 10 groups of porous granular material collision-friction tests are performed at the same rate.

10. The method for determining the critical safety diameter of emulsified droplets in a liquid energetic material synthesis reaction delivery pipeline according to claim 1, characterized in that: In step J, the movement speeds v1, v2, v3, v4, and v5 of the pistons do not exceed 25 m / s.

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