Test device and method for the safe number of days of highway transportation of long-term storage expired single-base propellant

Abstract

The invention discloses a test device and method for the safe days of highway transportation of long-storage expired single-base propellants. The test device comprises a sample tank, a vibration table, a heating mechanism arranged on the vibration table and a gas chromatograph. The determination method obtains the CO2 volume content of the sample gas in the sample tank after the heating vibration test, and obtains the evaluation parameter a of the safe days of transportation after each heating vibration test. 1,n and a 2,n The method of the present invention constructs the evaluation parameters of the safe days of road transportation of long-stored expired single-base propellants, and combines the color change of the gas in the sample tank to finally obtain the evaluation results of the safe days of road transportation, which can accurately characterize the actual situation of the propellant and effectively reduce the risk of accidents during transportation.

Description

Technical Field

[0001] The invention belongs to the field of quantitative detection of chemical stability of propellants, and in particular relates to a test device and method for the safe number of days of highway transportation of long-storage expired single-base propellants. Background Art

[0002] Explosives include explosives, propellants and solid propellants. Most explosives products need to be stored for a long time before use or destruction. Single-base propellants are the earliest propellants to be finalized and mass-produced. They are mainly composed of nitrocellulose NC and other additives, of which the NC content is usually around 95%. NC is an energetic substance that decomposes slowly even at room temperature. The decomposed nitrogen oxides can in turn catalyze this decomposition. Therefore, a small amount of stabilizer is added to the single-base propellant formula. The stabilizer reduces the decomposition rate of the single-base propellant by absorbing nitrogen oxides, allowing it to be stored for a longer time. However, the absorption capacity of the stabilizer is limited. When the stabilizer content decreases and the ability to absorb nitrogen oxides decreases to a certain extent, the decomposition rate of the single-base propellant increases and the chemical stability decreases. Its danger is much higher than that of newly produced single-base propellants and cannot continue to be stored.

[0003] At present, the single-base propellants that have been in long-term storage for decades and have expired need to be transported to a designated location for destruction. These highly dangerous single-base propellants can be transported from the warehouse to the designated destruction site by road transportation, but tests need to be conducted in advance to determine whether they can be transported. The existing determination method only considers the two stresses of heat or vibration (friction, impact) on the propellant, and cannot accurately characterize the actual conditions of the propellant during transportation, and cannot give the number of days for safe transportation, resulting in the inability to select a suitable destruction site based on the test results. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a test device and method for the safe number of days for road transportation of long-stored expired single-base propellants, which can realize the determination of the safe number of days for road transportation of long-stored expired single-base propellants.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] The test device for the safe days of highway transportation of long-term storage expired single-base propellant comprises a sample tank, a vibration table and a heating mechanism arranged on the vibration table, the heating mechanism comprises a detachably connected heating body and a fastening cover, the heating body is provided with a plurality of heating holes with open tops, the heating holes are used to heat the sample tank filled with the single-base propellant;

[0007] The test apparatus also includes a gas chromatograph.

[0008] The present invention also has the following technical features:

[0009] Specifically, the sample can comprises a can body with a cavity therein and a can cap matched with the can body, the can body and the can cap are both cylindrical structures, and a through pore is opened at the center of the upper surface of the can cap.

[0010] Furthermore, the wall thickness of the can body is 2 mm, the outer diameter is 30 mm, and the height is 80 mm; the outer diameter of the can cap is 36 mm, the height is 12 mm, the inner depth is 10 mm, and the diameter of the air hole is 2 mm.

[0011] Furthermore, a heat-insulating layer is provided on the bottom surface of the fastening cover.

[0012] The present invention also discloses a method for determining the safe number of days for road transportation of long-stored expired single-base propellants. The method is implemented by the above-mentioned test device for the safe number of days for road transportation of long-stored expired single-base propellants, and comprises the following steps:

[0013] Step 1, preparing an empty sample tank, a first sample tank filled with a long-storage expired single-base propellant, and a second sample tank, using a test device for the number of days of road transportation safety of long-storage expired single-base propellant to perform a heating and vibration test on the first sample tank and the second sample tank, and then cooling to room temperature, after the heating and vibration test, a first sample tank sample decomposition gas is generated in the first sample tank, and a second sample tank sample decomposition gas is generated in the second sample tank;

[0014] Step 2: Obtain the CO2 volume content of the gas in the empty sample tank and the CO2 volume content V of the decomposed gas of the first sample tank after the first heating and vibration experiment. 1,1 And the CO2 volume content V of the decomposition gas of the second sample tank sample after the first heating vibration experiment 2,1 , and we get the parallel difference Δ=|V 1,1 -V 2,1 |;

[0015] Step 3, observe whether brown gas appears in the first sample tank and the second sample tank after the first heating vibration experiment;

[0016] If so, the number of safe days for road transportation of long-term storage expired single-base propellant is determined to be 0;

[0017] If not, proceed to step 4;

[0018] Step 4: Repeat the heating vibration test on the first sample tank and the second sample tank, and obtain the CO2 volume content V of the decomposed gas in the first sample tank after each heating vibration test. 1,n , and the volume content of CO2 in the decomposed gas of the second sample tank V 2,n ; Then according to V 1,n 、V 2,nThe parallel difference Δ obtained in step 2 is used to obtain the transport safety days evaluation parameter a after each test. 1,n and a 2,n ,in,

[0019] a 1,n =(V 1,n -V 1,n-1 )÷Δ;

[0020] a 2,n =(V 2,n -V 2,n-1 )÷Δ;

[0021] Wherein, n is the number of heating vibration tests, n≥2;

[0022] When one of the following termination conditions is met, the heating vibration test is stopped; otherwise, the heating vibration test is repeated until one of the above termination conditions is met or the number of repeated tests reaches n=7, and the termination conditions include:

[0023] (1)a 1,n ≥6;

[0024] (2)a 2,n ≥6;

[0025] (3) Brown gas appears in the first sample tank;

[0026] (4) Brown gas appears in the second sample tank;

[0027] During the repeated heating vibration test, when the test is terminated by one of the above-mentioned termination conditions, the safe number of days for road transportation of long-storage expired single-base propellants is determined to be n-1; when the test is repeated until n=7 and any of the above-mentioned termination conditions is not met, the safe number of days for road transportation of long-storage expired single-base propellants is determined to be ≥7.

[0028] Furthermore, the heating temperature of the heating vibration treatment described in step 2 and step 4 is 70-72° C., the time of the vibration treatment is 7-9 hours, the vibration frequency is 9 Hz-11 Hz, and the amplitude is 15 mm-25 mm.

[0029] Furthermore, the long-storage-expired single-base propellant filled in the first sample tank and the second sample tank is cylindrical single-base propellant particles with a diameter and a height both not greater than 10 mm.

[0030] Furthermore, in step 4, the CO2 volume content of the decomposition gas of the sample in the first sample tank after each heating and vibration test = the CO2 volume content of the gas in the first sample tank after each heating and vibration test - the CO2 volume content of the gas in the empty sample tank; the CO2 volume content of the decomposition gas of the sample in the second sample tank after each heating and vibration test = the CO2 volume content of the gas in the second sample tank after each heating and vibration test - the CO2 volume content of the gas in the empty sample tank.

[0031] Furthermore, the filling mass of the single-base propellant in the first sample tank and the second sample tank is 9.5-10.5g.

[0032] Furthermore, when the first sample tank and the second sample tank are filled with the long-term storage expired single base

[0033] Propellant

[0034] hour:

[0035] If the mass of a single drug particle is m, in g, and β = 10 ÷ m, then:

[0036] If β≤15, it is considered that the number of propellant particles loaded in the first sample tank and the second sample tank is the same;

[0037] If 15<β≤60, the difference between the weight of the propellant loaded in the first sample tank and the second sample tank shall not exceed 0.2g;

[0038] If β>60, the difference in the sample weight of the propellant loaded in the first sample tank and the second sample tank shall not exceed 0.1g.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The method of the present invention simultaneously takes into account the synergistic effect of the two stresses of heat and vibration that the propellant will be subjected to in road transportation, which will destroy its stability, and constructs an evaluation parameter for the safe number of days for road transportation of long-storage expired single-base propellant. At the same time, combined with the color change of the gas in the sample tank, the evaluation result of the safe number of days for road transportation is finally obtained. The method can accurately characterize the actual situation of the propellant, thereby ensuring that the transportation personnel can coordinate the destruction points where the expired propellant can be transported according to the calculated safe transportation days, effectively reducing the risk of accidents occurring in the middle of the journey, and improving the efficiency of the expired propellant treatment. The method has a strong value for promotion and use.

[0041] Other advantages of the present invention are described in detail in the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic structural diagram of the test device of the present invention.

[0043] Description of the symbols in the figure:

[0044] 1-sample tank, 2-vibrating table, 3-heating mechanism, 4-gas chromatograph; 11-tank body, 12-tank cap, 31-heating body, 32-fastening cover. DETAILED DESCRIPTION

[0045] The following are specific embodiments of the present invention. It should be noted that, in the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integrated connection; it can be a direct connection or an indirect connection, etc. For ordinary technicians in this field, the specific meanings of the above terms in this technical solution can be understood according to specific circumstances.

[0046] In the present invention, unless otherwise specified, directional words such as "upper, lower, bottom, top" are usually defined based on the surface of the corresponding drawings, and "inside and outside" are defined based on the outline of the corresponding drawings.

[0047] It should be noted that propellant is one of the energy sources for launching guns and projectiles. It has the characteristics of "long-term storage and one-time use" and must have good stability. The stability of propellant is mainly chemical stability, which refers to the ability to delay decomposition and prevent automatic chemical changes during the storage period. Single-base propellant contains nitrocellulose NC. The nitrate group in NC can slowly decompose by itself. The gaseous decomposition products (such as NO2, NO, water vapor and HNO3) have a catalytic effect on the thermal decomposition of NC, and can even increase the decomposition rate of NC by dozens of times.

[0048] Different gaseous decomposition products have different effects on the decomposition of NC. NO2 will directly accelerate the oxidative decomposition of NC (NO2 will become NO after oxidation with NC, and NO will become NO2 after further oxidation). At the same time, the inorganic acid generated by NO2 and water can also accelerate the hydrolysis reaction of NC.

[0049] Increasing the temperature can accelerate the decomposition of NC. For example, at (70-130)℃, the decomposition rate of NC increases with the increase of temperature. When the temperature rises to above 140℃, the decomposition of NC becomes very intense. The purpose of this test is to determine the safe number of days for road transport of single-base propellants. During the test, the heating temperature of the sample should not be too low or too high, and it should be both in line with the actual situation and representative.

[0050] During the transportation of products, vibration is an inevitable part. Conventional cargo vibration testing simulates the dynamic impact of transportation vehicles on cargo during the circulation of goods. However, conventional cargo vibration testing mainly targets physical damage to goods, without considering the chemical impact of vibration converted into thermal stress on goods, nor the chemical impact of environmental thermal stress on goods.

[0051] The present invention is not limited to the following specific embodiments. The specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. As long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0052] Example 1

[0053] like Figure 1 As shown, this embodiment discloses a test device for the safe days of highway transportation of long-stored expired single-base propellant, comprising a sample tank 1, a vibration table 2 and a heating mechanism 3 arranged on the vibration table 2, the heating mechanism 3 comprising a detachably connected heating body 31 and a fastening cover 32, the heating body 31 is provided with a plurality of heating holes with open tops, and the heating holes are used to heat the sample tank 1 filled with the single-base propellant;

[0054] The experimental apparatus also includes a gas chromatograph 4 .

[0055] As a preferred solution of this embodiment, the sample tank 1 includes a tank body 11 with a cavity therein and a tank cap 12 matching the tank body 11, and a sealing gasket is arranged in the tank cap 12; the tank body 11 and the tank cap 12 are both cylindrical structures, and a through air hole is opened at the center of the upper surface of the tank cap 12.

[0056] As a preferred solution of this embodiment, the wall thickness of the tank body 11 is 2 mm, the outer diameter is 30 mm, and the outer height is 80 mm. The outer diameter of the tank cap 12 is 36 mm, the height is 12 mm, the inner depth is 10 mm, the diameter of the air hole is 2 mm, and the outer diameter of the sealing gasket is 30 mm and the thickness is 1.5 mm.

[0057] In this embodiment, the tank body 11 and the tank cap 12 are connected by threads, an external thread is provided on the upper outer wall of the tank body 11, an internal thread matching the external thread of the tank body 11 is provided on the inner wall of the tank cap 12, and a sealing gasket made of silicone rubber is provided inside the tank cap 12. Both the tank body 11 and the tank cap 12 are made of 316 stainless steel.

[0058] The (true) density of a single-base propellant is 1.60 g / cm 3 ~1.63g / cm 3 However, some single-base propellants are loose in texture and their pseudo-density is as low as 0.8g / cm 3 , some single-hole propellant has a bulk density of only 0.5g / cm 3 Therefore, there should be enough space in the sample tank to detect a variety of single-base propellants. The sample is not bound by the inner wall of the sample tank and can be fully vibrated. The volume of the sample tank should not be too large, otherwise a larger heating furnace is required, and the concentration of decomposition gas in the tank is too low to be easily detected.

[0059] According to the bulk density of 0.5g / cm 3 Calculation: 10g of propellant requires 20cm of space 3 .

[0060] Therefore, as a preferred embodiment, the tank wall thickness is 2 mm, the outer diameter is 30 mm, and the outer height is 80 mm.

[0061] The gas chromatograph 4 is used for gas detection. When the instrument configuration and setting parameters are valid, there are two main sources of detection errors: one is the injection of gas from the sample tank into the chromatograph; the other is the unstable state of the instrument.

[0062] When manually using an injection needle to collect gas and inject it into the chromatograph, problems such as gas leakage and poor repeatability of the injection action often occur. It relies too much on the operator's level and the human influence factor is relatively large. In order to reduce this factor affecting the test results, the present invention adopts technical means such as a gas collection device, a vacuum pump, and a quantitative tube. The operator only needs to insert the sampling needle of the gas collection device into the sample tank, and the gas chromatograph can automatically extract the decomposition gas for detection, thereby minimizing the error caused by human operation.

[0063] Generally, when using a gas chromatograph to detect gas, the same gas is required to be injected 2 to 3 times. When the chromatographic peak changes by ≤5%, the entire gas detection system (including gas sampling) is considered to be stable. However, the sample tank in this test is sealed. Due to negative pressure, continuous extraction of gas from the sample tank will result in a trend of gradually decreasing gas volume. Therefore, the method of continuously extracting gas from the sample tank can no longer be used to determine the stability of the system.

[0064] In summary, in this embodiment, when judging the state of the gas detection system, the method of "pumping the indoor gas from the gas sampling device into the quantitative tube, then injecting it into the chromatographic column for separation, detecting it with a thermal conductivity detector, and finally recording the chromatographic peak areas of oxygen and nitrogen; performing gas sampling and detection multiple times in succession; assuming that the chromatographic peak areas of oxygen and nitrogen detected by two consecutive samplings are marked as S1 and S2 respectively, and setting θ=|S1-S2|×2÷(S1+S2), when θ≤5%, judging that the instrument state is stable" is adopted.

[0065] As a preferred solution of this embodiment, the heating body is a cylindrical structure, and the heating body includes a cylindrical metal block with a heating wire wound on the outer wall, and the metal block sequentially wraps the heating body insulation layer and the heating body shell from the inside to the outside; 6 heating holes are evenly distributed along the circumference on the upper surface of the heating body, and the depth of the heating hole is 83mm; the heating hole includes an upper cylindrical hole and a lower cylindrical hole coaxially arranged through, the diameter of the upper cylindrical hole is 40mm, the depth is 14mm, and the diameter of the lower cylindrical hole is 36mm; 4 lower retaining springs are equidistantly installed in a circle at the lower end of the inner side surface of the lower cylinder of the heating hole, and 4 upper retaining springs are equidistantly installed in a circle at the upper end of the inner side surface of the lower cylinder, and the retaining spring is made of 316 stainless steel; when the bottom of the first sample tank is inserted into the bottom of the heating hole with the bottom facing down, the upper retaining spring and the lower retaining spring can clamp the first sample tank; a temperature sensor is arranged on the bottom surface of the heating hole;

[0066] A fastening cover insulation layer is arranged inside the fastening cover, and the fastening cover insulation layer is a flat cylindrical structure. The outer diameter of the fastening cover is consistent with the outer diameter of the heating body. The fastening cover can be connected to the heating body, for example, by setting upper and lower buckles and snapping them together. After the connection is fixed, the lower surface of the fastening cover can fit with the upper surface of the heating body.

[0067] The heating furnace is arranged directly above the vibration device and can be fixed on the vibration device by a clamp.

[0068] Example 2

[0069] This embodiment discloses a method for determining the safe number of days for highway transportation of long-term storage expired single-base propellant, which is implemented using the test device disclosed in Example 1 and includes the following steps:

[0070] Step 1, preparing an empty sample tank, a first sample tank filled with a long-storage expired single-base propellant, and a second sample tank, using a test device for the number of days of road transportation safety of long-storage expired single-base propellant to perform a heating and vibration test on the first sample tank and the second sample tank, and then cooling to room temperature, after the heating and vibration test, a first sample tank sample decomposition gas is generated in the first sample tank, and a second sample tank sample decomposition gas is generated in the second sample tank;

[0071] The filling quality of the long-term storage expired single-base propellant in the first sample tank and the second sample tank mainly considers the following aspects:

[0072] a. The sample weight is too small, and the decomposition gas produced by the propellant when heated is too little to be detected by gas chromatography;

[0073] b. The sample weight is too large, and the propellant decomposes too violently due to factors such as heat accumulation, posing a safety hazard;

[0074] c. The testing laboratory has quantitative requirements for explosives;

[0075] d. Several propellant samples can be tested simultaneously.

[0076] In order not to destroy the integrity of the propellant particles, the mass value of the propellant placed in the sample tank for testing must be discontinuous. The (true) density of single-base propellant is generally 1.60g / cm 3 ~1.63g / cm 3 Within the range, the mass of some larger-sized non-porous propellants is shown in Table 1 (smaller-sized propellants and propellants with holes are omitted):

[0077] Table 1

[0078]

[0079]

[0080] Table 1 The mass of some larger-sized non-porous propellants and the number of particles required to weigh 10g

[0081] Table 1 only lists some of the larger non-porous propellants. There are a large number of propellants with holes and propellants with three-dimensional dimensions less than 5mm that are not listed. For example, a single-hole single-base propellant with a hole diameter of 2mm, an outer diameter of 5mm, a height of 10mm, and a true density of 1.60g / cm 3 , the apparent density (including pores) is 1.344g / cm 3 The weight of each pill is 0.2638g, 37 pills are 9.7606g, and 39 pills are 10.2882g.

[0082] As can be seen from Table 1, for propellants with a diameter of ≥8mm and a height of ≥9mm, because the mass of a single propellant is relatively large, if the propellant particles cannot be crushed, the sample weighing range needs to be appropriately relaxed. There are also some propellant columns that have combustion holes designed (such as single hole, 7 holes, 14 holes, multiple holes, etc.), so the mass of propellants with the same outer diameter and height will be lighter than the mass listed in Table 1; furthermore, even if the propellant particles are produced with the same size, their mass will be biased, and after long-term storage, some components of the propellant will volatilize, so the mass will also be reduced. Therefore, taking various factors into consideration, the sample weighing range is determined to be 9.5g~10.5g. There is also a special case in Table 1. The propellant particles with a diameter of 8mm and a height of 10mm, when the density is 1.60g / cm 3 When weighing 12 or 13 grains, they are all within the range of 9.5g to 10.5g; when the density is 1.63g / cm 3 When weighing, only 12 grains can be weighed to be within the range of 9.5g to 10.5g.

[0083] For large propellant particles (such as propellant particles with a diameter of 10 mm and a height of 10 mm, and propellant particles with a diameter of 9 mm and a height of 10 mm), as long as the weight is within the range of 9.5 g to 10.5 g, the number of particles in the two parallel samples must be the same;

[0084] When the particle size and density are small (non-porous propellant has true density, and porous propellant has false density), it is very likely that "even if the weight of the two parallel samples is within the range of 9.5g to 10.5g, the number of particles is different", that is, the mass difference of the parallel samples is too large (such as parallel sample 1 is 9.55g, and parallel sample 2 is 10.45g). Then, after the heating and vibration treatment, the parallel difference Δ of the characteristic decomposition gas of the two parallel samples may be too large. It is possible that: after the nth heating and vibration treatment of the propellant sample, the degree of obvious decomposition is reached, but the a calculated by this method is 1，n <6 or a 2，n If the value is less than 6, it means that the sample has not been obviously decomposed, resulting in a misjudgment. Therefore, it is necessary to develop an easy-to-operate method to achieve the goal of making the number of particles in two parallel samples as close as possible by weighing the mass (weighing the amount of medicine with a balance and then pouring it into the sample jar).

[0085] In this embodiment, the test results of the two parallel samples in the first sample tank and the second sample tank are used to characterize possible fluctuations in the data of the same sample, so it is necessary to try to ensure that the mass of the two parallel samples is not only within the range of 9.5g to 10.5g, but also to ensure that the number of particles of the propellant is consistent.

[0086] Even if the propellant is produced in the same process and the same batch, its size and mass may be different. When the total mass of the propellant placed in the sample tank cannot be within the range of 9.5g to 10.5g, as a preferred scheme of this embodiment, it can be adjusted by replacing other grains of the propellant so that the total mass is within the range of 9.5g to 10.5g. It is prohibited to crush the propellant grains to adjust the total mass.

[0087] If the mass of a single drug particle is m, in g, and β = 10 ÷ m, then:

[0088] If β≤15, there is no need to adjust the propellant particles, and it is considered that the number of propellant particles loaded in the first sample tank and the second sample tank is the same;

[0089] If 15<β≤60, it is necessary to replace the propellant particles so that the difference between the propellant sample weights in the first sample tank and the second sample tank is no more than 0.2g;

[0090] If β>60, it is necessary to replace the propellant particles so that the difference in the sample weight of the propellant loaded in the first sample tank and the second sample tank is no more than 0.1g.

[0091] After determining the filling mass of the propellant and completing the weighing, the first sample can and the second sample can containing the propellant are placed in the two heating holes of the heating body respectively, so that the first sample can and the second sample can are clamped by the retaining rings in the heating holes respectively; the fastening cover with the insulation layer facing downward is covered on the upper surface of the heating body. Then the heating furnace mechanism is fixed on the vibration table by a clamp, and the heating furnace is heated to 71°C. After the temperature stabilizes, the vibration device selects the random vibration mode; first heat and vibrate for 0.5 hours, stop the vibration, check the connection of the first sample can, the second sample can, the heating furnace, and the vibration device to ensure that the connection of each component is normal and not loose, and then start the formal heating vibration test, and start the timing from 0; after vibrating at 71°C for 8 hours, remove the fastening cover, take out the first sample can and the second sample can in the heating hole, cool to room temperature, and wait for detection; the empty sample can without propellant is not vibrated at 71°C for 8 hours.

[0092] Turn on the gas chromatograph, set the temperature of the thermal conductivity detector to 250°C and the temperature of the chromatographic column to 80°C; after the instrument is stable, turn on the vacuum pump of the gas chromatograph workstation to draw the indoor gas from the gas sampling device into the quantitative tube, then inject it into the chromatographic column for separation and thermal conductivity detector detection, and finally record the chromatographic peak areas of oxygen and nitrogen; perform gas sampling and detection multiple times in succession; the chromatographic peak areas of oxygen and nitrogen detected by two consecutive injections are S1=87690740 and S2=86362598, respectively, and θ=1.53%<5%, indicating that the gas chromatograph is in a stable state and can start detection;

[0093] Insert the sampling needle into the air hole at the center of the upper surface of the can cap of the empty sample can, turn on the vacuum pump of the gas chromatograph workstation, extract the gas in the empty sample can for testing, and record the chromatographic peak areas of oxygen and nitrogen, and the chromatographic peak area of ​​CO2; pull out the sampling needle inserted into the empty sample can;

[0094] Insert the sampling needle into the first sample tank and the second sample tank containing the propellant respectively, extract gas for testing respectively, and record the chromatographic peak areas of oxygen and nitrogen, and the chromatographic peak area of ​​CO2;

[0095] When the single-base propellant is heated, the nitrocellulose NC decomposes, which will cause a decrease in the stabilizer content, a decrease in the mass of the condensed phase, an increase in the content of characteristic decomposition gases, changes in mechanical properties, a decrease in the nitrogen content of NC, and so on. Among them: the determination of the stabilizer content, the determination of mechanical properties, and the determination of the nitrogen content of NC are all destructive tests, and the 7-cycle test requires 7 times the sample volume of a single test; the determination of the stabilizer content and the determination of the nitrogen content of NC are both chemical methods, and the test steps are cumbersome. The determination of the mass of the condensed phase and the determination of the characteristic decomposition gas content are both non-destructive tests, and the sample volume required for the 7-cycle test is equal to the sample volume of a single test; they are all physical methods, and the operation is simple. Considering that the propellant is placed in a stainless steel sample can, the mass of the propellant is several times smaller than that of the stainless steel sample can. If the mass of the propellant needs to be accurately weighed, the propellant needs to be poured out of the sample can and weighed, and then poured back into the sample can after weighing.

[0096] This operation (pouring out, weighing, and then pouring it back into the sample can) has two disadvantages that affect the weighing accuracy: ① The integrity of the propellant after thermal decomposition is likely to be destroyed, and pouring it back and forth may cause the propellant debris to be scattered; ② When the propellant is heated, the oily substances inside the propellant will seep out, causing the propellant debris to stick to the inner wall of the sample can and may not be poured out.

[0097] The parameter to be measured is preliminarily determined to be the characteristic decomposition gas content. When the stabilizer works, there are no nitrogen oxides in the decomposition gas of the single-base propellant; when the stabilizer does not work (that is, the chemical stability deteriorates and there is a greater risk in the transportation of single-base propellants), nitrogen oxides will appear in the decomposition gas. However, CO2 is always present throughout the entire decomposition process, and the CO2 content is in a corresponding relationship with the degree of decomposition. Therefore, the present invention uses the CO2 content as the parameter to be measured. At the same time, for the sake of safety, the appearance of brown gas in the decomposition gas is also used as a basis for judgment, so as to make up for the possible loopholes in the CO2 content as a parameter to be measured.

[0098] Step 2: Obtain the CO2 volume content of the gas in the empty sample tank and the CO2 volume content V of the decomposed gas of the first sample tank after the first heating and vibration experiment. 1,1 And the CO2 volume content V of the decomposition gas of the second sample tank sample after the first heating vibration experiment 2,1 , and we get the parallel difference Δ=|V 1,1 -V 2,1 |;

[0099] Among them, the CO2 volume content V of the decomposition gas of the first sample tank sample after the first heating vibration experiment 1,1 =CO2 volume content in the first sample tank measured after the first heating vibration test - CO2 volume content in the empty sample tank; CO2 volume content of the decomposition gas of the second sample tank measured after the first heating vibration test V 1,1=CO2 volume content in the second sample tank after the first heating and vibration test - CO2 volume content in the empty sample tank.

[0100] Step 3, observe whether brown gas appears in the first sample tank and the second sample tank after the first heating vibration experiment;

[0101] If so, the number of safe days for road transportation of long-term storage expired single-base propellant is determined to be 0;

[0102] If not, proceed to step 4;

[0103] Step 4: Perform n heating vibration tests on the first sample tank and the second sample tank, and record the volume content V of the decomposed gas of the first sample tank after each test. 1,n , and the volume content of CO2 in the decomposition gas of the second sample tank after each test V 2,n ; Then according to V 1,n 、V 2,n The parallel difference Δ obtained in step 2 is used to obtain the transport safety days evaluation parameter a after each test. 1,n and a 2,n :

[0104] a 1,n =(V 1,n -V 1,n-1 )÷Δ;

[0105] a 2,n =(V 2,n -V 2,n-1 )÷Δ;

[0106] Where n is the number of heating vibration tests, n≥2; after each heating vibration test, the volume content of CO2 in the decomposition gas of the first sample tank is V 1,n =CO2 volume content in the first sample tank - CO2 volume content of the gas in the empty sample tank; CO2 volume content of the decomposed gas in the second sample tank V 2,n =CO2 volume content in the first sample tank - CO2 volume content of the gas in the empty sample tank.

[0107] The termination conditions of the above heating vibration test are: a. 1,n or a 2,n Greater than or equal to 6 or brown gas appears in the first sample tank or the second sample tank;

[0108] If the above-mentioned test termination conditions are not met, the test shall be repeated until the test termination conditions are met or the test is repeated until n=7; during the repeated test, when the test termination conditions are met and the test is terminated, the number of safe days for road transportation of long-storage expired single-base propellants is determined to be n-1; when the test is repeated until n=7 and any of the above-mentioned termination conditions is not met, the number of safe days for road transportation of long-storage expired single-base propellants is determined to be ≥7.

[0109] It should be noted that failure to meet the above test termination conditions means: a. 1,n or a 2,n None of the four conditions, i.e., a, is greater than or equal to 6 or brown gas appears in the first sample tank or the second sample tank. 1,n and a 2,n Both are less than 6, and no brown gas appears in the first sample tank, and no brown gas appears in the second sample tank.

[0110] Application Example 1

[0111] This application example adopts the test method disclosed in Example 2. The propellant to be evaluated is a single-base propellant that has been in stock for 20 years. Its characteristics are: single hole, outer diameter of 5mm, length of 10mm, mass of a single grain m=0.3285g, β=10÷m=30, 15<β<60, so the difference between the sample weight in the first sample tank and the second sample tank should be ≤0.2g. After filling the propellant, the sample weight of the first sample tank is finally measured to be 9.8466g, and the sample weight of the second sample tank is 9.9852g;

[0112] The V measured after the first heating vibration test in this embodiment is 1,1 =0.16%, V 2,1 =0.13%; the calculated parallel difference Δ =0.03%;

[0113] Then, the caps of the three sample cans were loosened respectively to separate the caps from the can bodies; there was no brown gas inside the first sample can containing propellant and the second sample can;

[0114] Then tighten the caps and bodies of the three sample cans again, and conduct the second heating vibration test to measure V 1,2 =0.13%, V 2,2 =0.14%, there is no brown gas in the first sample tank and the second sample tank; a 1,2 =-1.0<6, a 2,2 =0.3<6;

[0115] The third heating vibration test was carried out to obtain V 1,3 =0.10%, V 2,3 =0.07%; a 1,3 =-1.0<6, a2,3 =-2.3<6; there is no brown gas in the first sample tank and the second sample tank;

[0116] The fourth heating vibration test was carried out and V 1,4 =0.13%, V 2,4 =0.10%, a 1,4 =1.0<6, a 2,4 =1<6; there is no brown gas in the first sample tank and the second sample tank;

[0117] The fifth heating vibration test was carried out to obtain V 1,5 =0.15%, V 2,5 =0.13%, a 1，5 =0.7<6, a 2,5 =1.0<6; there is no brown gas in the first sample tank and the second sample tank;

[0118] The sixth heating vibration test was carried out and V 1,6 =0.10%, V 2,6 =0.16%, a 1,6 =-1.7<6, a 2，6 =1.0<6; there is no brown gas in the first sample tank and the second sample tank;

[0119] The 7th heating vibration test was carried out and V 1,7 =0.13%, V 2,7 =0.18%, a 1，7 =-1.0<6, a 2,7 =0.7<6, no brown gas appears in the first sample tank and the second sample tank, and it is determined that the safe days for road transportation of the single-base propellant is ≥7 days.

[0120] In the highway transportation of propellant, the transportation mileage usually ranges from 1600 to 2400 km, and the longest mileage is 2400 km. Assuming that the gravel road is 1000 km and the flat road is 1400 km, the speed of the dangerous goods transport vehicle is 35 km / h on the flat road and about 80 km / h on the gravel road, the transport time of the transport vehicle is 8 hours per day, and the time required is 5.8 days. Taking into account some other influencing factors, the upper limit of the test cycle is determined to be 7 times, each time 8 hours, that is, after 7 cycles of heating and vibration, if the safety of the propellant has not deteriorated, the next cycle of heating and vibration will not be continued.

[0121] Single-base propellants contain a large amount of nitrocellulose NC. The nitrate group in NC can slowly decompose by itself, and the nitrogen oxides in the gaseous decomposition products have the effect of self-catalytic decomposition. Therefore, single-base propellants contain about 1% of stabilizers, which can absorb nitrogen oxides and prevent catalytic effects. When the stabilizer content is reduced to a certain level, its ability to absorb nitrogen oxides is weakened. With the increase of nitrogen oxides, the decomposition degree of NC is intensified, and the content of decomposition gas produced increases significantly.

[0122] After the nth heating and vibration, the CO2 content of the characteristic decomposition gas increased significantly compared with the (n-1)th time, indicating that the nth heating and vibration caused the single-base propellant to decompose significantly more, the stabilizer did not work, and the stability deteriorated. Many random factors lead to certain differences in the test results between parallel samples of the same sample, which is called parallel difference. When the stability of the propellant deteriorates, the difference between two adjacent test results is significantly greater than the parallel difference. According to previous experience, the newly produced single-base propellant has good uniformity, and the volatility of the test data of parallel samples after the same heating and vibration treatment does not exceed 3 times the parallel difference; while the uniformity of long-stored propellants is slightly worse, and the volatility of the test data will be slightly larger. In summary, after the heating and vibration treatment of long-stored single-base propellants, when the increase in the decomposition gas test results in the same sample tank exceeds 6 times the parallel difference Δ compared with the test results before heating and vibration, it is considered that this heating and vibration has deteriorated the stability of the propellant.

[0123] In addition, in the previous test paper method for testing the stability of single-base propellants, there have been cases where the test paper did not change color (the test paper will change color when the nitrogen oxide content reaches a certain level) but brown decomposition gas (brown decomposition gas is the color of nitrogen oxides) was seen in the sample. Therefore, when testing the stability of the test paper method, if the test paper does not change color but brown decomposition gas is seen, it can also be judged that the stability of the sample has deteriorated. Therefore, the brown decomposition gas is also used as a criterion for the deterioration of the stability of the propellant.

[0124] Ultimately, the criterion for the deterioration of the stability of single-base propellants was determined as follows: after the single-base propellant is heated and vibrated n times, when the CO2 content in the same sample can increases by more than 6Δ compared to the (n-1)th test result, or brown decomposition gas appears in the sample can, it is considered that this heating and vibration has caused the stability of the single-base propellant to deteriorate.

[0125] Therefore, if any parallel sample shows stability deterioration, the heating and vibration test will no longer be carried out, and the number of safe transportation days will be calculated by subtracting 1 from the number of heating times this time.

[0126] Application Example 2

[0127] A single-base propellant (single hole, outer diameter 5mm, length 10mm) that has been in stock for 5 years was thermally aged to reduce its stabilizer content to 0.1%. This product is called a long-storage expired simulated propellant. This patent is used to determine the number of safe days for road transportation of the long-storage expired simulated propellant.

[0128] Weigh the mass of a single drug particle m = 0.3272g, β = 10÷m = 31, 15 < β < 60, so the difference between the two parallel samples should be ≤ 0.2g, so after adjustment by particles, the sample weight of parallel sample 1 is 10.1586g, and the sample weight of parallel sample 2 is 10.0635g; put the first sample tank and the second sample tank on the workbench with the openings facing upward, respectively put the propellant parallel sample 1 and parallel sample 2, and tighten the tank caps to assemble; assemble another empty sample tank without propellant;

[0129] In this embodiment, it is measured that: V 1,1 =0.48%, V 2,1 =0.43%; Δ=0.05%; there is no brown gas in the first sample tank and the second sample tank; the experiment termination condition is not met;

[0130] After the second heating vibration test, V 1,2 =0.53%, V 2,2 =0.48%; a 1,2 =1.0<6, a 2,2 =1.0<6; There is no brown gas in the first sample tank and the second sample tank; The experiment termination condition is not met;

[0131] After the third heating vibration test, V 1,3 =0.60%, V 2,3 =0.51%; a 1,3 =1.4<6, a 2,3 =0.6<6; There is no brown gas in the first sample tank and the second sample tank; The experiment termination condition is not met;

[0132] After the 4th heating vibration test, V 1,4 =0.63%, V 2,4 =0.56%, a 1,4 =0.6<6, a 2,4 =1.2<6, there is no brown gas in the first sample tank and the second sample tank; the experiment termination condition is not met;

[0133] After the 5th heating vibration test, V 1,5 =1.36%, V 2,5 =0.65%, a 1,5 =14.6, a 2,5 =1.4, there is no brown gas in the first sample tank and the second sample tank; but a 1,5=14.6>6, the experiment termination condition is met, and the heating vibration test is no longer carried out; it is determined that the safe number of days for road transportation of the sample is 5-1=4 days.

[0134] Application Example 3

[0135] The test steps adopted in this embodiment are the same as those disclosed in Example 1, with the difference being that in this embodiment, the aqueous NC stored in a warehouse for 7 years is used as the sample to be tested, and this patent is used to determine its safe days for road transportation. There is no stabilizer in the aqueous NC sample, and the nitrogen oxides produced by its thermal decomposition will accelerate the decomposition of NC, so it will quickly reach the stage of stability deterioration. From a safety perspective, only 5g is filled in the sample tank (instead of 10g for single-base propellant), and the difference in the weighing weight of the two parallel samples should be ≤0.1g (NC is in fine powder form), so the weighing weight of parallel sample 1 is 5.0186g, and the weighing weight of parallel sample 2 is 4.9722g;

[0136] After the first heating vibration test, the measured V 1,1 =0.20%, V 2,1 =0.07%; Δ=0.13%; there is no brown gas in the first sample tank and the second sample tank; the experiment termination condition is not met;

[0137] After the second heating vibration test, the measured V 1，2 =0.28%, V 2，2 =0.18%; calculate a 1，2 =0.6<6, a 2，2 =0.8<6, there is no brown gas in the first sample tank and the second sample tank; the experiment termination condition is not met;

[0138] After the third heating vibration test, the measured V 1,3 =0.36%, V 2,3 =0.32%; calculated to get a 1，3 =0.6<6, a 2，3 =1.1<6; There is no brown gas in the first sample tank and the second sample tank; The experiment termination condition is not met;

[0139] After the 4th heating vibration test, the measured V 1,4 =0.48%, V 2,4 =0.37%, calculate a 1，4 =0.9<6, a 2，4 =0.4<6; There is no brown gas in the first sample tank and the second sample tank; The experiment termination condition is not met;

[0140] After the fifth heating vibration test, the measured V 1,5 =0.56%, V 2,5=0.45%, calculate a 1，5 =0.6, a 2，5 =0.6; there is no brown gas in the first sample tank and the second sample tank; the experiment termination condition is not met;

[0141] After the 6th heating vibration test, V 1,6 =1.06%, V 2,6 =0.65%, calculate a 1，6 =3.8, a 2，6 =1.5, brown gas appears in the first sample tank, the experiment termination condition is met, and the heating vibration test is no longer carried out; it is determined that the safe number of days for road transportation of this sample is 6-1=5 days.

[0142] In this embodiment, after heating and vibrating for 6 times, brown gas appeared inside the first sample tank. The appearance of brown means that the propellant sample in the first sample tank has entered the accelerated decomposition stage. However, the a of the first sample tank 1，6 =3.8<6, reason for analysis: the water distribution in the water-containing NC is very uneven, so the decomposition degree of the two parallel samples after thermal vibration is quite different, resulting in Δ being too large, which may lead to misjudgment.

[0143] The above results show that adding "the presence of brown gas" as one of the criteria can reduce the probability of misjudgment.

[0144] Comparative Example 1

[0145] The sample in Example 1 was tested according to the method of the friction sensitivity test of Group 3 Test 3 (b) in GB / T 14372-2016 "Methods for the approval and sub-item determination of explosives for dangerous goods transport". The hardness of long-storage propellant is very large. The sample was processed by a drill bit to make a powder that can pass through a sieve with a mesh diameter of 0.50mm±0.05mm. 20mg was taken out from it to test the friction sensitivity. The test result was that the friction sensitivity was unqualified. According to this test result, the propellant is too dangerous to be transported. However, the test results of the stabilizer content, stability-Viennese repetition ten times method, 75℃ thermal stability, and impact sensitivity of the propellant were all qualified, among which the stabilizer content and stability-Viennese repetition ten times method had no significant difference from the production indicators (there was no 75℃ thermal stability in the factory indicators; the impact sensitivity calculation method tested at the factory was different from GB / T 14372-2016 implemented for transportation, and the two test results could not be compared).

[0146] After comprehensive analysis of various test results, it was determined that the reason for the unqualified friction sensitivity was that the sample's stability deteriorated due to inappropriate sample processing. However, the volume and mass of the entire unprocessed pellets are relatively large, and cannot be tested according to the friction sensitivity test method of Group 3 Test 3 (b) in GB / T14372-2016. Therefore, it is not possible to determine whether the long-storage propellant can be transported based on the friction sensitivity test results.

[0147] In summary, the testing device and the testing method of the present invention can be used to test the safe number of days for highway transportation of long-storage expired single-base propellants.

Claims

1. A method for determining the number of safe days for highway transportation of long-term storage expired single-base propellants, characterized in that: The method is implemented by a test device for the safe number of days of highway transportation of long-term storage-expired single-base propellant, the test device comprising a sample tank (1), a vibration table (2) and a heating mechanism (3) arranged on the vibration table (2), the heating mechanism (3) comprising a detachably connected heating body (31) and a fastening cover (32), the heating body (31) being provided with a plurality of heating holes with open tops, the heating holes being used to heat the sample tank (1) filled with the single-base propellant; The test device also includes a gas chromatograph (4); The method comprises the following steps: Step 1, preparing an empty sample tank, a first sample tank filled with a long-storage expired single-base propellant, and a second sample tank, using a test device for the number of days of road transportation safety of long-storage expired single-base propellant to perform a heating and vibration test on the first sample tank and the second sample tank, and then cooling to room temperature, after the heating and vibration test, a first sample tank sample decomposition gas is generated in the first sample tank, and a second sample tank sample decomposition gas is generated in the second sample tank; Step 2: Obtain the CO2 volume content of the gas in the empty sample tank and the CO2 volume content V of the decomposed gas of the first sample tank after the first heating and vibration experiment. 1,1 And the CO2 volume content V of the decomposition gas of the second sample tank sample after the first heating vibration experiment 2,1 , and we get the parallel difference Δ=|V 1,1 -V 2,1 |; Step 3, observe whether brown gas appears in the first sample tank and the second sample tank after the first heating vibration experiment; If so, the number of safe days for road transportation of long-term storage expired single-base propellant is determined to be 0; If not, proceed to step 4; Step 4: Repeat the heating vibration test on the first sample tank and the second sample tank, and obtain the CO2 volume content V of the decomposed gas in the first sample tank after each heating vibration test. 1,n , and the volume content of CO2 in the decomposed gas of the second sample tank V 2,n ; Then according to V 1,n 、V 2,n The parallel difference Δ obtained in step 2 is used to obtain the transport safety days evaluation parameter a after each test. 1,n and a 2,n ,in, and 1,n =(V 1,n -V 1,n-1 )÷Δ; and 2,n =(V 2,n -V 2,n-1 )÷Δ; Wherein, n is the number of heating vibration tests, n≥2; When one of the following termination conditions is met, the heating vibration test is stopped; otherwise, the heating vibration test is repeated until one of the above termination conditions is met or the number of repeated tests reaches n=7, and the termination conditions include: (1)a 1,n ≥6； (2)a 2,n ≥6； (3) Brown gas appears in the first sample tank; (4) Brown gas appears in the second sample tank; During the repeated heating vibration test, when the test is terminated by one of the above-mentioned termination conditions, the safe number of days for road transportation of long-storage expired single-base propellants is determined to be n-1; when the test is repeated until n=7 and any of the above-mentioned termination conditions is not met, the safe number of days for road transportation of long-storage expired single-base propellants is determined to be ≥7.

2. The method for determining the safe number of days for highway transportation of long-storage expired single-base propellant according to claim 1, characterized in that: The sample can (1) comprises a can body (11) with a cavity therein and a can cap (12) matching the can body (11), wherein a sealing gasket is arranged in the can cap (12); the can body (11) and the can cap (12) are both cylindrical structures, and a through pore is provided at the center of the upper surface of the can cap (12).

3. The method for determining the safe number of days for highway transportation of long-storage expired single-base propellant as claimed in claim 2, characterized in that: The wall thickness of the tank body (11) is 2 mm, the outer diameter is 30 mm, and the outer height is 80 mm; the outer diameter of the tank cap (12) is 36 mm, the height is 12 mm, and the inner depth is 10 mm; the diameter of the air hole is 2 mm; the outer diameter of the sealing gasket is 30 mm and the thickness is 1.5 mm.

4. The method for determining the safe number of days for highway transportation of long-storage expired single-base propellant according to claim 1, characterized in that: A heat-insulating layer is provided on the bottom surface of the fastening cover (32).

5. The method for determining the safe number of days for highway transportation of long-storage expired single-base propellant as claimed in claim 1, characterized in that: The heating temperature of the heating vibration experiment described in step 2 and step 4 is 70-72° C., the vibration time is 7-9 hours, the vibration frequency is 9 Hz-11 Hz, and the amplitude is 15 mm-25 mm.

6. The method for determining the safe number of days for highway transportation of long-term storage expired single-base propellant as claimed in claim 1, characterized in that: The long-storage-expired single-base propellant is a cylindrical single-base propellant with a particle diameter and a height both not greater than 10 mm.

7. The method for determining the safe number of days for highway transportation of long-storage expired single-base propellant as claimed in claim 1, characterized in that: In step 4, the CO2 volume content of the decomposed gas of the sample in the first sample tank after each heating and vibration test = the CO2 volume content of the gas in the first sample tank after each heating and vibration test - the CO2 volume content of the gas in the empty sample tank; the CO2 volume content of the decomposed gas of the sample in the second sample tank after each heating and vibration test = the CO2 volume content of the gas in the second sample tank after each heating and vibration test - the CO2 volume content of the gas in the empty sample tank.

8. The method for determining the safe number of days for highway transportation of long-storage expired single-base propellant as claimed in claim 1, characterized in that: The filling mass of the single-base propellant in the first sample tank and the second sample tank is 9.5-10.5g.

9. The method for determining the safe number of days for highway transportation of long-storage expired single-base propellant as claimed in claim 1, characterized in that: When filling the first sample tank and the second sample tank with long-storage expired single-base propellant: If the mass of a single drug particle is m, in g, and β = 10 ÷ m, then: If β≤15, the number of propellant particles loaded in the first sample tank and the second sample tank is the same by adjusting the propellant particles; If 15<β≤60, the propellant particles are adjusted so that the difference between the propellant sample weights loaded in the first sample tank and the second sample tank is no more than 0.2g; If β>60, the propellant particles are adjusted so that the difference in the sample weight of the propellant loaded in the first sample tank and the second sample tank is no more than 0.1 g.

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