Preparation method of combustion type warm cloud catalyst

Abstract

The invention discloses a preparation method of a combustion type warm cloud catalyst, the combustion type warm cloud catalyst comprises a first slurry and a second slurry, the first slurry and the second slurry are prepared by layered inclined pouring and curing, the first slurry comprises 35%-70% of an oxidizing agent, 3%-8% of a combustion agent, 10%-16% of a moisture absorbent and 13%-21% of an adhesive, the second slurry comprises 60%-70% of an oxidizing agent, 15%-17% of a combustion agent and 13%-25% of an adhesive. Through a method of layered pouring of two medicaments, hygroscopic salts are thoroughly isolated from external water vapor, the problem of moisture absorption failure caused by long-term storage is solved, the components and proportions of the oxidant and the incendiary agent are optimized, the combustion temperature is changed, the diameter of aerosol particles generated after combustion is controlled, and the problem of poor moisture absorption is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of warm cloud catalysts, and particularly to a preparation method of a combustion-type warm cloud catalyst. Background Art

[0002] Artificial rainfall enhancement operations are mainly carried out in the northern regions, and the operation targets are mainly cold clouds. The catalysts used are mainly ice-forming agents such as silver iodide. In the southern regions, warm cloud precipitation is prevalent in summer, and there are still key technical problems to be solved for warm cloud rainfall enhancement, especially for warm convective clouds. Currently, there is a lack of applicable catalysts.

[0003] The particulate matter generated after the combustion of the warm cloud flares and rockets currently used in our country's operations is relatively small. The particle concentration of particles with a diameter greater than 0.5 microns accounts for only about 50%. The nucleation rate and hygroscopic growth efficiency are relatively low, and the rainfall enhancement efficiency is not high. Improve the formula and preparation technology of the combustion-type warm cloud catalyst, overcome the technical problems of narrow particle size spectrum, low nucleation efficiency, and poor feasibility of traditional warm cloud catalysts; the particle concentration of particles with a diameter greater than 0.5 microns in the combustion-type catalyst particulate matter increases from the existing 50% to 80% - 90%, and the catalytic efficiency is significantly improved;

[0004] The particle concentration of particles with a diameter greater than 0.5 microns generated after the combustion of both types of pyrotechnic agents accounts for only about 50%. Their nucleation efficiency is low, feasibility is poor, and catalytic efficiency is low. The newly developed hygroscopic pyrotechnic agents internationally can generate particulate matter with a higher concentration of particle size of 0.5 - 1 micron after combustion. There are problems such as the aerosol particle size being too small after combustion to form large cloud droplets, poor hygroscopicity, little and slow moisture absorption, low rainfall enhancement efficiency, poor economic benefits, being prone to moisture absorption and failure after long-term storage, resulting in ignition failure and inability to continue burning. Therefore, a preparation method of a combustion-type warm cloud catalyst needs to be developed. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a combustion-type warm cloud catalyst to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention is implemented according to the following technical solution:

[0007] On the one hand, the present invention includes the following steps:

[0008] Pretreat the oxidant, combustion agent, and hygroscopic agent.

[0009] Sequentially add the adhesive, combustion agent, and hygroscopic agent and stir for 30 minutes. Add the oxidant in multiple batches, stir at intervals, and finally add the curing agent and mix for 30 minutes to obtain the first slurry. The first slurry includes 35% - 70% oxidant, 3% - 8% combustion agent, 10% - 16% hygroscopic agent, and 13% - 21% adhesive;

[0010] The adhesive and the combustion agent are added successively and stirred for 30 min. The oxidant is added in multiple portions, and the curing agent is added with intermittent stirring and mixed for 30 min to obtain the second slurry. The second slurry comprises 60%-70% of oxidant, 15%-17% of combustion agent, and 13%-25% of adhesive;

[0011] The first slurry and the second slurry are prepared by layered pouring and curing. The first slurry is poured obliquely to 90% of the capacity of the prefabricated shell; after standing for 30 min, the second slurry is poured obliquely into the remaining space of the shell.

[0012] Furthermore, during the preparation of the first slurry and the second slurry, the stirring temperature is controlled at 40-45°C and the humidity is less than 30%.

[0013] Furthermore, the pretreatment includes drying the oxidant, the combustion agent, and the moisture absorbent at 60-65°C until the water content is <0.5%, and grinding and sieving the dried raw materials through a 20-mesh sieve in an environment with a temperature of 20-35°C and a humidity of ≤25%.

[0014] Furthermore, the oxidant includes one or more of potassium perchlorate, sodium perchlorate, and calcium perchlorate; the combustion agent includes one or more of magnesium powder and calcium powder; the moisture absorbent includes one or more of calcium chloride, potassium chloride, and sodium chloride.

[0015] Furthermore, the adhesive is hydroxyl-terminated polybutadiene liquid rubber or random carboxyl liquid polybutadiene liquid rubber; the curing agent is toluene diisocyanate, and the dosage of the curing agent is 6%-8% of the mass of the adhesive.

[0016] Furthermore, the first slurry contains 2% by mass of magnesium oxide additive for adjusting the combustion activation energy.

[0017] Furthermore, in the layered pouring process, the interfacial bonding between slurry A and B is ensured to be dense by an inclined pouring angle of 15-30° and an interval time, and the interval time is greater than 30 min.

[0018] On the other hand, a combustion-type warm cloud catalyst comprises the first slurry and the second slurry, which are prepared by layered inclined pouring and curing. The first slurry comprises 35%-70% of oxidant, 3%-8% of combustion agent, 10%-16% of moisture absorbent, and 13%-21% of adhesive, and the second slurry comprises 60%-70% of oxidant, 15%-17% of combustion agent, and 13%-25% of adhesive.

[0019] The beneficial effects of the present invention are:

[0020] The present invention relates to a preparation method of a combustion-type warm cloud catalyst. Compared with the prior art, the present invention has the following technical effects:

[0021] By using the method of layered pouring of two agents, the present invention completely isolates the hygroscopic salts from external water vapor, solves the problem of hygroscopic failure during long-term storage, optimizes the composition and ratio of the oxidant and the fuel, changes the combustion temperature, and controls the diameter of the aerosol particles generated after combustion, thus solving the problem of poor hygroscopicity. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the particle distribution of the product after combustion of a combustion-type warm cloud catalyst of the present invention. Detailed Embodiments

[0023] The present invention will be further described below through specific embodiments. The illustrative embodiments and explanations of the present invention are used to explain the present invention, but do not limit the present invention.

[0024] As Figure 1 shown, a preparation method of a combustion-type warm cloud catalyst includes the following steps:

[0025] Example 1

[0026] For the agent to make Slurry A, 67% potassium perchlorate is used as the oxidant, 4% magnesium powder is used as the fuel, a mixture of 5% calcium chloride and 11% potassium chloride is used as the hygroscopic agent, 13% hydroxyl-terminated polybutadiene liquid rubber is used as the adhesive, and toluene diisocyanate is used as the curing agent, with a mass of 6% of the adhesive.

[0027] For the agent to make Slurry B, 70% potassium perchlorate is used as the oxidant, 17% magnesium powder is used as the fuel, 13% hydroxyl-terminated polybutadiene liquid rubber is used as the adhesive, and toluene diisocyanate is used as the curing agent, with a mass of 6% of the adhesive.

[0028] The process of making the catalyst from the agents is as follows:

[0029] First step, set the drying oven to 65°C, and dry the above-mentioned potassium perchlorate, magnesium powder, calcium chloride, and potassium chloride respectively until the water content is less than 0.5%.

[0030] Second step, in an environment with a temperature of 30°C and a humidity of 25%, grind the dried potassium perchlorate, magnesium powder, calcium chloride, and potassium chloride respectively with a ball mill and pass through a 20-mesh sieve.

[0031] Step 3: Prepare Slurry A. Set the temperature of the stirring tank at 45°C and keep it constant. Add hydroxyl-terminated polybutadiene liquid rubber to the stirring tank, then add magnesium powder, calcium chloride, and potassium chloride and stir for 30 minutes. Add potassium perchlorate in 5 portions, with 5 minutes of stirring after each addition before the next addition. Finally, add the curing agent and mix for 30 minutes to form Slurry A. This step requires the environmental humidity to be less than 30%.

[0032] Step 4: Slowly and obliquely pour Slurry A into the prefabricated housing, with the pouring volume being 90% of the housing capacity.

[0033] Step 5: Prepare Slurry B. Set the temperature of the stirring tank at 45°C and keep it constant. Add hydroxyl-terminated polybutadiene liquid rubber to the stirring tank, then add magnesium powder and stir for 30 minutes. Add potassium perchlorate in 5 portions, with 5 minutes of stirring after each addition before the next addition. Finally, add the curing agent and mix for 30 minutes to form Slurry A. This step requires the environmental humidity to be less than 30%.

[0034] Step 7: Slowly and obliquely pour Slurry B into the remaining part of the prefabricated housing.

[0035] Step 8: Place the product in an oven to complete curing.

[0036] Example 2

[0037] For the agent to make Slurry A, take potassium perchlorate at a mass ratio of 60% as the oxidizer, magnesium powder at 3% as the fuel, a mixture of 5% calcium chloride and 11% potassium chloride as the moisture absorbent, and 21% hydroxyl-terminated polybutadiene liquid rubber as the adhesive. Take toluene diisocyanate as the curing agent, with a mass of 7% of the adhesive.

[0038] For the agent to make Slurry B, take potassium perchlorate at a mass fraction ratio of 60% as the oxidizer, magnesium powder at 15% as the fuel, 25% hydroxyl-terminated polybutadiene liquid rubber as the adhesive, and take toluene diisocyanate as the curing agent, with a mass of 7% of the adhesive.

[0039] The process of making the agent into a catalyst is as follows:

[0040] Step 1: Set the drying oven to 60°C and dry the above-mentioned potassium perchlorate, magnesium powder, calcium chloride, and potassium chloride respectively until the water content is less than 0.5%.

[0041] Step 2: In an environment with a temperature of 35°C and a humidity of 25%, grind the dried potassium perchlorate, magnesium powder, calcium chloride, and potassium chloride respectively with a ball mill and pass through a 20-mesh sieve.

[0042] Step 3: Prepare Slurry A. Set the temperature of the mixing tank at 43°C and keep it constant. Add hydroxyl-terminated polybutadiene liquid rubber to the mixing tank, then add magnesium powder, calcium chloride, and potassium chloride and stir for 30 minutes. Add potassium perchlorate in 5 portions, with 5 minutes of stirring after each addition before the next addition. Finally, add the curing agent and mix for 30 minutes to form Slurry A. This step requires the environmental humidity to be less than 30%.

[0043] Step 4: Slowly and obliquely pour Slurry A into the prefabricated housing, with the pouring volume being 90% of the housing capacity.

[0044] Step 5: Prepare Slurry B. Set the temperature of the mixing tank at 43°C and keep it constant. Add hydroxyl-terminated polybutadiene liquid rubber to the mixing tank, then add magnesium powder and stir for 30 minutes. Add potassium perchlorate in 5 portions, with 5 minutes of stirring after each addition before the next addition. Finally, add the curing agent and mix for 30 minutes to form Slurry A. This step requires the environmental humidity to be less than 30%.

[0045] Step 7: Slowly and obliquely pour Slurry B into the remaining part of the prefabricated housing.

[0046] Step 8: Place the product in an oven for curing to completion.

[0047] Example 3

[0048] For the agent to make Slurry A, take sodium perchlorate with a mass ratio of 35% and calcium perchlorate with a mass ratio of 30% as oxidants, 5% magnesium powder and 3% calcium powder as combustion agents, a mixture of 5% calcium chloride and 5% sodium chloride as a moisture absorbent, 2% magnesium oxide as an auxiliary agent, and 15% random carboxyl liquid polybutadiene liquid rubber as an adhesive. Take toluene diisocyanate as the curing agent, with a mass of 8% of the adhesive.

[0049] For the agent to make Slurry B, take potassium perchlorate with a mass fraction ratio of 65% as an oxidant, 15% magnesium powder as a combustion agent, 2% magnesium oxide as an auxiliary agent, 18% random carboxyl liquid polybutadiene liquid rubber as an adhesive. Take toluene diisocyanate as the curing agent, with a mass of 8% of the adhesive.

[0050] The process of making the agent into a catalyst is as follows:

[0051] Step 1: Set the drying oven to 60°C and dry the above-mentioned sodium perchlorate, calcium perchlorate, magnesium powder, calcium powder, calcium chloride, sodium chloride, and magnesium oxide respectively until the water content is less than 0.5%.

[0052] Step 2: In an environment with a temperature of 30°C and a humidity of 20%, grind the dried sodium perchlorate, calcium perchlorate, magnesium powder, calcium powder, calcium chloride, sodium chloride, and magnesium oxide respectively with a ball mill and pass through a 20-mesh sieve.

[0053] Step 3: Prepare Slurry A. Set the temperature of the stirring tank at 40 °C and keep it constant. Add random carboxyl liquid polybutadiene liquid rubber into the stirring tank, then add magnesium powder, calcium powder, calcium chloride, sodium chloride, and magnesium oxide and stir for 30 minutes. Add calcium perchlorate in three portions, with 5 minutes of stirring after each addition before the next addition. Then add sodium perchlorate in three portions, with 5 minutes of stirring after each addition before the next addition. Finally, add the curing agent and mix for 30 minutes to form Slurry A. The environmental humidity requirement for this step is less than 30%.

[0054] Step 4: Slowly and obliquely pour Slurry A into the prefabricated shell, with the pouring amount being 90% of the shell's capacity.

[0055] Step 5: Prepare Slurry B. Set the temperature of the stirring tank at 45 °C and keep it constant. Add random carboxyl liquid polybutadiene liquid rubber into the stirring tank, then add magnesium powder and magnesium oxide and stir for 30 minutes. Add potassium perchlorate in five portions, with 5 minutes of stirring after each addition before the next addition. Finally, add the curing agent and mix for 30 minutes to form Slurry A. The environmental humidity requirement for this step is less than 30%.

[0056] Step 7: Slowly and obliquely pour Slurry B into the remaining part of the prefabricated shell.

[0057] Step 8: Put the product into an oven for curing to completion.

[0058] Table 1 Influence of Oxidizer Ratio on Combustion Rate and Particle Size

[0059]

[0060] As shown in Table 1, the combustion rate is measured by a timer, and the particle size distribution is analyzed by scanning electron microscopy (SEM) to study the influence of the ratio of oxidizer to adhesive on the combustion rate and particle size. As the mass ratio of the oxidizer increases, more oxidizer supports the combustion process, and the combustion time is significantly reduced (from 34 seconds in the control group to 13 seconds in Experiment 2). The increase in the combustion rate is beneficial for the catalyst to burn out as soon as possible, and it is easier for the product to obtain larger particles; a large amount of gas is generated during the combustion of the adhesive, which disperses the particles during the agglomeration process and is not conducive to the production of large particles. Therefore, reducing the adhesive content is beneficial for the formation of agglomerated particles.

[0061] When the proportion of the oxidizer rises to 70%, the volume proportion of particles larger than 0.5 μm reaches 91.8%, which is 26.6% higher than that of the control group. The physical mechanism of the increase in particle size is as follows: the increase in the combustion speed shortens the residence time of liquid droplets in the high-temperature zone, promotes the rapid collision and condensation between particles, and forms aggregates with larger particle sizes. At the same time, the decrease in the mass of the adhesive reduces the amount of gas generated during combustion, and the low gas jet volume provides more space for the agglomeration of particles. Meteorological research shows that the cloud droplet growth efficiency is positively correlated with the initial particle size. When particles above 0.5 μm are used as condensation nuclei, the initial radius of cloud droplets is larger, which can shorten the collision and growth time from aerosol to raindrop by about 30%-40%.

[0062] Table 2 Comparison of the effects of desiccant combinations on the moisture absorption efficiency

[0063]

[0064] As shown in Table 2, the moisture absorption experiment was carried out at 25°C and RH90%. The cloud droplet generation time was used to observe the effect of the desiccant combination on the moisture absorption efficiency through a cloud chamber. Among them, the moisture absorption rate of single calcium chloride (Experiment A) reached 0.18 g / g·h, which was 3.6 times that of the control group (without desiccant); the composite formula (Experiment C) was further increased to 0.22 g / g·h, which was 22% higher than that of the single component. This is due to the synergistic effect of calcium chloride (strong moisture absorption but easy to deliquesce) and sodium chloride (stable moisture absorption but low rate): calcium chloride provides an initial high moisture absorption driving force, and sodium chloride maintains the continuous moisture absorption ability. The moisture absorption equilibrium amount (0.51 g / g) is 325% higher than that of the control group, which means that more water vapor can be adsorbed per unit mass of aerosol, forming a thicker moisture absorption layer and accelerating the condensation and growth of cloud droplets. The experiment shows that the cloud droplet generation time of the composite desiccant group is shortened to 23 minutes, which is 49% less than 45 minutes of the control group. This is because the high moisture absorption efficiency quickly forms a water film on the surface of aerosol particles, promotes the condensation nucleation of water vapor, and reduces the "induction period" of cloud droplet generation.

[0065] Table 3 Comparison of the effects of storage time on the moisture absorption performance

[0066]

[0067] As shown in Table 3, under the storage conditions of 25°C and RH 70%, the influence of storage time on the moisture absorption performance was compared by the static weighing method. The moisture absorption rate of the control group (non-stratified) decreased by 41.7% after 6 months of storage. The main reason was that the desiccant was deliquesced and agglomerated due to long-term contact with water vapor in the air, losing its moisture absorption activity. However, in the stratified casting group, through physical isolation of the agent (inner combustion agent + outer desiccant), the contact area between the desiccant and external water vapor was reduced by more than 80%. After 12 months, the moisture absorption rate only decreased by 18.2%, and the effective period was extended to 2.3 times that of the control group. Thermogravimetric analysis (TGA) showed that the desiccants (calcium chloride, sodium chloride) in the stratified structure did not show obvious lattice water (weight gain rate < 5%) during storage, while lattice water appeared in the control group after 3 months (weight gain rate 12%), proving that the stratification process effectively inhibited the moisture absorption of the catalyst during storage and solved the industry problem of "storage failure" of traditional products.

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a combustion-type warm cloud catalyst, comprising the following steps: Pre-treat the oxidant, fuel, and hygroscopic agent. Add the adhesive, fuel, and hygroscopic agent in sequence and stir for 30 min. Add the oxidant in multiple portions, with intermittent stirring, and finally add the curing agent and mix for 30 min to obtain the first slurry. The first slurry comprises 35%-70% oxidant, 3%-8% fuel, 10%-16% hygroscopic agent, and 13%-21% adhesive. Add the adhesive and fuel in sequence and stir for 30 min. Add the oxidant in multiple portions, with intermittent stirring, and add the curing agent and mix for 30 min to obtain the second slurry. The second slurry comprises 60%-70% oxidant, 15%-17% fuel, and 13%-25% adhesive. The first slurry and the second slurry are prepared by stratified casting and curing. Pour the first slurry obliquely to 90% of the capacity of the prefabricated shell; after standing for 30 min, pour the second slurry obliquely into the remaining space of the shell.

2. The preparation method of the combustion-type warm cloud catalyst according to claim 1, wherein: During the preparation of the first slurry and the second slurry, control the stirring temperature at 40-45 °C and the humidity at less than 30%.

3. The preparation method of the combustion-type warm cloud catalyst according to claim 1, wherein: The pre-treatment includes drying the oxidant, fuel, and hygroscopic agent at 60-65 °C until the water content is <0.5%, and grinding and sieving the dried raw materials through a 20-mesh sieve in an environment with a temperature of 20-35 °C and a humidity of ≤25%.

4. The preparation method of the combustion-type warm cloud catalyst according to claim 1, characterized in that: The oxidant includes one or more of potassium perchlorate, sodium perchlorate, and calcium perchlorate; the fuel includes one or more of magnesium powder and calcium powder; the hygroscopic agent includes one or more of calcium chloride, potassium chloride, and sodium chloride.

5. The preparation method of the combustion-type warm cloud catalyst according to claim 1, characterized in that: The adhesive is hydroxyl-terminated polybutadiene liquid rubber or random carboxyl liquid polybutadiene liquid rubber; the curing agent is toluene diisocyanate, and the dosage of the curing agent is 6%-8% of the mass of the adhesive.

6. The preparation method of the combustion-type warm cloud catalyst according to claim 1, characterized in that: The first slurry contains 2% by mass of magnesium oxide additive for adjusting the combustion activation energy.

7. The preparation method of the combustion-type warm cloud catalyst according to claim 1, wherein: In the stratified casting process, the interfacial bonding between slurry A and B is ensured to be dense by an inclined casting angle of 15-30° and an interval time, and the interval time is greater than 30 min.

8. A combustion-type warm cloud catalyst, characterized in that, Comprising a first slurry and a second slurry, the first slurry and the second slurry are prepared by stratified inclined casting and curing. The first slurry comprises 35%-70% oxidant, 3%-8% fuel, 10%-16% hygroscopic agent, and 13%-21% adhesive, and the second slurry comprises 60%-70% oxidant, 15%-17% fuel, and 13%-25% adhesive.

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