Agi dispersion for cloud seeding and seeding techniques with this solution

Abstract

The present invention relates, on the one hand, to the chemicals industry and, on the other, to the service industry, for managing areas where a certain amount of water precipitation in the form of rain is desired. The real advantage of the present invention optimises the number of ice or water droplet-forming nuclei in the clouds where they are applied, in addition to allowing for faster and less expensive cloud seeding, which means that a smaller volume of seeding dispersion has to be handled. The present silver iodide dispersion consists of an ionic solution for seeding clouds, characterised in that the continuous phase, in other words, the solvent of the dispersion, is a mixture of at least 1) toluene, with 2) p-xylene, 3) o-xylene, 4) 2-butoxyethanol, and 5) methylcyclohexane.

Description

[0001] Dispersal of Agí for Cloud Seeding and Techniques

[0002] SOWING WITH THIS SOLUTION

[0003] FIELD OF INVENTION

[0004] The present invention is related to the chemical products industry on the one hand and to the weather modification services industry on the other, particularly to the stimulation of rain through the technique known as Cloud Seeding with the aim of improving the efficiency of precipitation and inducing rain in geographical areas of interest.

[0005] BACKGROUND OF THE INVENTION

[0006] Until now, in the state of the art, there have been multiple manufacturing processes of substances to stimulate the precipitation of moisture contained in air formations called clouds.

[0007] Lack of understanding the physical chemistry of clouds has led to the development of ineffective methods and devices for extracting water from clouds. The assumption that clouds are water vapor, without knowing how that vapor is found, has led to some inventions failing. For example, an air cooler to condense water vapor and bring that water to the Earth's surface.

[0008] Nimbus stratus or nimbus cumulus clouds produce rain, snow, sleet, or hail. Because nimbus clouds are dense with water, they appear darker than other clouds. Nimbus clouds form at low altitudes and are usually evenly distributed across the sky.

[0009] The U.S. Patent Office has granted patents related to rain formation and propagation by induction for nearly 100 years. In 1920, U.S. Patent No. 1,338,343 was granted for a process and apparatus for producing intense artificial clouds, fogs, or mists.

[0010] In this invention, the atomization of an anhydrous chloride, such as tin chloride or titanium chloride, is used.

[0011] Cloud seeding has been practiced for many years around the world. Scientific articles have reported on cloud seeding experiences in the United States, Israel, China, South Africa, Argentina, and other countries, as follows. In general, cloud seeding successes have been documented as statistical differences in rainfall probability, rather than direct measurements of cause and effect. Cloud seeding is now considered a potentially very valuable tool for enhancing rainfall yields. Research progress has produced encouraging results that will eventually make cloud seeding a practical technique for overcoming drafts by inducing programmable rainfall and developing water supplies for many regions.Although the effectiveness of cloud seeding is currently a matter of academic debate, many countries have invested significant resources and efforts in direct cloud seeding. While there are still no reports of a proven or reproducible direct causal effect of cloud seeding and precipitation, claims of successful correlations support international efforts.

[0012] The seed-feed mechanism is a unique and well-characterized rain-induction process where the relevance of the present invention is significant. The seed-feed mechanism typically occurs when a double layer of clouds, one above the other, leaves a gap of approximately 500 m in 1500 m of air.

[0013] The seed-feeder mechanism is defined as the introduction of ice or condensed water nuclei from above into a lower-level liquid cloud. The introduction of condensation nuclei can initiate precipitation from the low-level cloud layer. As the condensation nuclei are introduced into the lower liquid cloud, ice crystals or condensates can grow by deposition, which can cause precipitation from the low cloud. There are characteristics in observed soundings and surface observations that can alert a forecaster to the possibility of the seed-feeder process occurring within 12 hours.

[0014] In one type of seed-feeder cloud system, nuclei can form in the upper cloud and can be produced around airborne dust particles made of clay / arc, volcanic ash / dust, or vermiculite. Nuclei can also be formed from artificially dispersed silver iodide, potassium chloride, simple salt, or other compounds. Suitably dispersed particles in the micro- and nanoscale ranges can efficiently seed cloud nuclei using as little as 500 g per square kilometer.

[0015] The precipitation resulting from a seed-feed mechanism depends largely on the proper characterization of all atmospheric parameters, as well as spatial variables such as the thickness of the upper and lower clouds and the intervening air space. The distributions of temperature, pressure, wind and humidity within the clouds, in the air space, as well as the corresponding surface variables. Furthermore, a variable that has also been noted in the numerous experiences with cloud seeding is the seeding agent. Both its chemical composition and its physicochemical form of application.

[0016] State-of-the-art rain induction technologies typically involve poor decision making based on low-precision, long-distance atmospheric parameter measurements, low-accuracy procedures, and crude and / or unsafe planter spreading practices.

[0017] For example, China has practiced rain induction (or hail prevention) by launching ground-to-cloud rockets. Explosive payloads were delivered using missiles to disperse planting materials, where decision-making was also based on long-range measurements from the ground to the clouds, or simply from visual assessments such as cloud morphology aided by atmospheric parameters on the ground.

[0018] Other approaches involve aircraft flights into the clouds, or the dispersion of smaller particles floating from ground stations into the clouds.

[0019] At least some known efforts to counter the effects of water scarcity and drought have focused on weather modification techniques such as cloud seeding and cloud ionization. Cloud seeding involves injecting silver iodide particles or other suitable substances from an aircraft into the atmosphere, allowing moisture to accumulate on the particles, freeze, and fall to the ground as water. However, cloud seeding is generally expensive, and its effectiveness is limited by the supply of particles and the flight time of the aircraft injecting the particles into the atmosphere. Cloud ionization involves radio frequency antennas that emit negatively charged ions into the atmosphere. In theory, the negatively charged ions will increase the likelihood that supercooled moisture droplets will collide with a frozen core, thereby turning into rain.However, the effectiveness of ionization of terrestrial clouds is debatable.

[0020] J. Warner & S. Twomey in 1956 published The Use of Silver Iodide for Seeding Individual Clouds, Tellus, 8:4, 453-459, DOI: 10.3402 / tellusa. v8¡4.9037, where the seeding of super-cooled clouds (cryogenic seeding) is described, where temperatures are below -5 o C, with a suspension of silver iodide in acetone, in which the silver iodide serves as a nucleus for the formation of ice crystals. This suspension is found at a concentration of 100 or 200 g / L (10 g of Agí in 50 or 100 cc of acetone) and is released as smoke by aircraft flying through the upper levels of the cloud or just below the cloud base. It is important to note that Agí has ​​a solubility of 3x10' 7 g / 100 mL (20 °C), that is, practically insoluble in water and Acetone.

[0021] From the reported experiments it appears clear that silver iodide is an effective agent for inducing precipitation in super-cooled clouds whose temperatures are below - 5 o C. The time required for precipitation to be released is usually about 20 to 25 minutes after seeding in the case of a cumulus cloud, but may be longer in the case of bypassable layers. The question of whether precipitation will reach the ground clearly depends on the amount released, the height of the cloud base above the ground, and the dryness of the air between them. In most cases, however, any reasonably deep cloud that was seeded produced rain that reached the ground. It is interesting to note that these conclusions are very similar to those of Squires and Smith (1949) regarding the effect of seeding supercooled clouds with dry ice.

[0022] Silver iodide is considered by far the most effective substance for the nucleation of ice crystals in supercooled clouds, due to its insolubility, which makes the crystals remain undistorted from their solid state, and because the shape of the crystal lattice is very similar to that of ice, such that it functions as a mold that induces the formation of supercooled water crystals on the exposed face of the crystal. However, several modern studies indicate that it is not as efficient and that it is not possible to explain this cryogenic capacity with the similarity between the crystal structures alone.

[0023] On January 29, 1974, a patent application was published, with a priority filed on September 4, 1972 in the U.S.A., to protect an invention of AMAN DP; KOFF I, entitled "UNIFORM SIZE PARTICLE GENERATOR", where a method and apparatus are described for the generation of fine particles, for example, silver iodide, from a nebulizer for cloud seeding. The nebulizer consists of a large container in which a constant level of a combustible or highly volatile suspension, such as a solution of silver iodide in acetone, is maintained. An ultrasonic generator in the base of the container produces micron-sized droplets of the solution into the airspace above the solution. The droplets are ejected from the container by a stream of solvent-laden air toward a burner or vent which burns the solvent.However, the formation of nucleation sites, regardless of the particle size added to the suspension with acetone, is generated from the sublimation of silver iodide by burning said suspension, then these vapors condense and form the crystallization nuclei. The number of nucleation sites is determined in a device called a Cloud Chamber.

[0024] Chamber (in English), in which the number of nuclei generated in the Ag aerosol is indirectly determined at different temperatures, resulting in quantities between 10 8 and 10 11Nuclei / liter of product. The more crystal nuclei that can be introduced into the cloud, the greater the probability of inducing increased precipitation, or of inducing precipitation when the number of nuclei naturally present in the atmospheric aerosol is insufficient to break the colloidal stability that results in a precipitation efficiency of zero.

[0025] In document CA850537 A to POWER, B., published on September 1, 1970, cloud seeding with silver iodide to nucleate ice is described. For this purpose, an aqueous dispersion of silver iodide and a substance for holding the silver iodide in dispersion is atomized and distributed in a precipitation-susceptible atmosphere to form fine droplets which act as nuclei for precipitation. The solubilizing substance is preferably a co-solute, of which water-soluble iodides are preferred, including sodium iodide, potassium iodide, or ammonium iodide, or it may be sodium chloride. The solution used is an aqueous solution containing 30-92% (preferably 80-90%) of Agí saturation, which has a concentration of 145 g / L (14.5 g of Agí in 100cc of Kl, Nal, NH4CI or NaCI solvent), however there are no records of its commercial application in cloud seeding operations,which can be explained because what is needed to break the colloidal equilibrium of the hydro meteors in a cloud for precipitation to occur, as is the case with tiny subcooled water droplets in the upper parts of clouds, are surfaces on which the formation of ice crystals can be induced, or in the case of tiny water droplets at a temperature above the freezing point in the middle or lower parts of a cloud, particles are required that form droplets that can grow overcoming the Kelvin Effect and that in the case that they are soluble in water take advantage of the colligative properties to obtain droplets of a size that when breaking generate new points of droplet growth through the collision-coalescence process that give rise to droplets of a size that allows them to precipitate, the introduction of solubilized silver iodide could not generate any of these effects.,

[0026] From the analysis of the state of the art on the use of silver iodide for cloud seeding, it can be seen that there are still aspects of this use that have not been fully studied for optimal use of the seeding agent.

[0027] It is clear that the more active nuclei for the formation of water droplets (hygroscopic seeding) or ice (cryogenic seeding), the better the use of silver iodide.Thinking about having a particle reduction device such as a mill or an atomizer, or an ultrasonic generator, or even a burner, has some drawbacks that opened the opportunity to develop what is proposed in this patent to facilitate the application of the product, to have a way to generate the nucleation points by a method other than sublimation, which does not involve the risks of handling flammable substances or pyrotechnic material in aircrafts that are used for their dispersion in clouds, and on the other hand, generate these crystallization nuclei that generate more efficient active surfaces for the technique known as cryogenic seeding and that at the same time allows it to behave as a condensation nucleus with high effectiveness to be applied in the technique known as hygroscopic seeding in areas of clouds that contain liquid water at temperatures above 0 ° C.

[0028] Most Agl aerosols used operationally for weather modification are produced by sublimation through the combustion of silver iodide solutions in acetone or by pyrotechnic generation methods (DeMott, 1995). Atomized Agl-acetone solutions are usually combusted in a propane flame. During subsequent cooling in the atmosphere, aerosol particles are formed. Currently, instead of pure Agl, mixtures such as Agl, AgCl, and paradichlorobenzene are used to produce particles with improved ice nucleation ability compared to Agl alone (probably due to improved wetting ability by generating more water-friendly modified surfaces). The optimum sublimation temperature for silver iodide was found to be 1023 K. The optimum suspension concentration in acetone was determined to be 2 wt % (Shevkunov, 2005).

[0029] However, the progress of science applied to the generation of Ag-based aerosols, the average effectiveness of cloud seeding operations using these sublimation techniques through the combustion of solutions in acetone or through pyrotechnic compounds, is still questionable.

[0030] The use of Ag in solution increases the number of condensation nuclei, but modifies the thermal effect of the crystals of this substance.

[0031] OBJECTIVES OF THE INVENTION

[0032] One of the objectives of the present invention is to achieve a cloud seeding agent that optimizes the number and / or effectiveness of condensation nuclei, ice formation nuclei of the clouds where it is applied.

[0033] Another objective is to reduce the complexity of cloud seeding application, making it faster and less expensive, requiring handling of less volume of seeding dispersion and reducing the risk of handling combustible, explosive or pyrotechnic materials in the operation of aircraft used for cloud seeding.

[0034] Yet another objective of the present invention is the application of a mixture of solvents and organic substances that achieve the synthesis of a miscellar dispersion of silver iodide with an ultra-fine particle size, that is, of nanometric size, which allows us to generate highly effective crystallization nuclei or condensation nuclei by spraying micrometric drops, in liquid and cold, in the regions of the clouds that are susceptible.

[0035] Yet another objective of the present invention is to achieve an increase in the number of condensation nuclei, without losing the cryogenic effect of the seeding agent.

[0036] And all those objectives and advantages that will become apparent upon reading this description and the examples added for illustrative, but not limiting, purposes.

[0037] DESCRIPTION OF THE INVENTION

[0038] One of the embodiments of the present invention consists of a true solution of Ag (silver iodide) in an organic solvent or mixture of solvents. Any organic solvent that achieves ionic dissolution of the iodide can be used. Since the particle size is equal to the silver iodide ion, this would be the smallest possible particle size, and this would mean that a true solution of silver iodide with a concentration of 400 ppm (0.4 g / l) would generate 1.7 X 10 20condensation nuclei, where the dispersing phase is a mixture of organic solvents, derived from petroleum.

[0039] Although the above concentration is the maximum concentration, it is possible to make lower concentration solutions depending on the planting objectives.

[0040] Achieving a homogeneous and stable dispersion of silver iodide is an important achievement, however, obtaining this dispersion at the nanometric solution level, which allows generating aerosols with crystallization nuclei and / or cloud condensation nuclei, by spraying them in liquid and cold form, using micrometric drops, to induce an increase in precipitation efficiency through cloud seeding techniques, is a novel and disruptive proposal! a .

[0041] On the other hand, achieving a silver iodide product in solution means that the volume required to handle a small amount is the same as handling a suspension or even a colloid. The number of silver iodide nuclei when achieving a nanoscale solution is only limited by the amount that the continuous phase can dissolve, until reaching saturation. Reducing the particle size of silver iodide is simpler through a dissolution process than through grinding. The same applies to the step of incorporating silver iodide into the cloud to be seeded. With a nanoscale solution, its application will not depend on expensive seeding processes, such as combustion of the dispersed material, or the need for an ultrasonic generator.

[0042] Silver iodide has a solubility in water of 3 X 10 ~ 7g / 100 ml at a temperature of 20 °C, it can be said that silver iodide is practically insoluble in water. The same happens with its solubility in acetone.

[0043] During the development process of the present invention it was observed that silver iodide is not soluble in an aqueous solution of ammonia.

[0044] The cryogenic effect of silver iodide cannot be explained simply by the similarity of its crystalline structure to that of ice; it is necessary to create crystallization nuclei that have active surfaces similar to water in order to induce the formation of ice crystals by the immersion or wharf processes. Those generated by sublimation processes are not very effective, even though heterogeneous complexes of silver iodide with chlorine and sodium, for example, have been achieved. In many cases, these nuclei formed by sublimation are susceptible to contamination by some gases present in the atmosphere, decreasing their effectiveness. The nuclei generated by the organometallic complex generated by the invention result in active surfaces that do not have this disadvantage.

[0045] Working on solvents for silver iodide, and starting from the fact that it was not soluble in acetone, as in the case of aqua regia, the combination of different solvents and organic substances was tested, reaching the conclusion that a combination of toluene, whose synonym is ethylbenzene, with p-xylene, o-xylene and 2-butoxyethanol, and ethyl derivatives and the already tested acetone achieved the solubility of silver iodide, resulting in a nanometric solution with the appropriate characteristics to take advantage of the thermal qualities.

[0046] With this combination of solvents and organic substances, a miscellaneous dispersion of silver iodide of 400 ppm could be achieved, which is equivalent to a concentration of 400 mg of silver iodide / liter of solution.

[0047] The atomic weight of iodine is 126.90 g, that of silver is 107.87 g. The molecular weight of silver iodide is 234.77 g, therefore, it can be said that one mole of silver iodide weighs 234.77 g.

[0048] If one mole weighs 234.77 g, how many moles is 400 mg of silver iodide? 400 mg is equal to 0.4 g and is equivalent to 1.70 x 10- 3 moles, and according to Avogadro's number, one mole of any substance has 6.023 X 10 23 molecules, this is equivalent to multiplying:

[0049] (1.70 X 10- 3 ) X (6.023 X 10 23 ) =1.023 X 10 20 Agl molecules / liter.

[0050] It has been verified that the crystals are not uni-molecular; we estimate that there are between 49 and 120 molecules per nanocrystal, so the number of nuclei generated is of the order of 1 x 10 18 and 2x10 18 nuclei / liter.

[0051] In the case of cryogenic seeding, to introduce the same number of nucleation centers into the clouds with state-of-the-art products using sublimation, a larger amount of silver iodide would be required to obtain similar results.

[0052] So, with respect to the product aspect of the present invention, our invention consists of a dispersion of 400 mg of silver iodide in one liter of a combination of 1) toluene, with 2) p-xylene, 3) o-xylene, 4) 2-butoxyethanol, and 5) methylcyclohexane. This would be the qualitative composition.

[0053] As a quantitative composition we will define that toluene can vary between 16.4 and 97.9%, and that p-xylene varies between 0.7 and 50%, with respect to the final solution.

[0054] O-xylene, on the other hand, can be present in amounts between 1.9 and 7.7%. The effect of these two amounts was measured, and a similar effect was obtained.

[0055] Butoxyethanol can be present between 2.7 and 9.9% and methylcyclohexane varies between 0.8 and 9.8%.

[0056] A mixture of 16.4% toluene, 50% p-xylene, 7.7%, 9.9% 2-butoxyethanol was made, making the first solvent composition A.

[0057] A mixture of 97.9% toluene, 0.7% p-xylene, 1.4% o-xylene was prepared making the second solvent composition B.

[0058] A mixture of 57% toluene, 25.35% p-xylene, 5% o-xylene, 9.9% 2-butoxyethanol and 2.75% methylcyclohexane was prepared. The third solvent composition C was obtained.

[0059] Solvent D is a pre-mixed product resulting from the fractional distillation of petroleum and is known as thinner. In addition to there being several types of these, being a natural product, its composition is very varied, both qualitatively and quantitatively. EXAMPLES

[0060] Example 1

[0061] Solvent composition A was taken and 400 mg of silver iodide was added, an organic solution was obtained, resulting in a completely transparent solution.

[0062] Example 2

[0063] Solvent composition B was taken and 400 mg of silver iodide was added, an organic solution was obtained, resulting in a completely transparent solution.

[0064] Example 3

[0065] Solvent composition C was taken and 400 mg of silver iodide was added, an organic solution was obtained, resulting in a completely transparent solution.

[0066] Example 4

[0067] Solvent composition D was taken and 400 mg of silver iodide was added, an organic solution was obtained, resulting in a completely transparent solution.

[0068] These compositions allow the nano-crystal structure of silver iodide to be maintained, with all the advantages that this entails.

[0069] And in terms of application, several functional methods were tested: 1) the product is sprayed in the cloud using a cold-spray device, using a pump and a sprayer, or 2) using a pressurized air tank and a sprayer.

[0070] The means to upload the spray product to the cloud are already state-of-the-art. Drones, airplanes, helicopters, hot air balloons, among others, have been used.

[0071] The invention has been sufficiently described to enable a person of ordinary skill in the art to reproduce and obtain the results mentioned herein. However, any person skilled in the art relevant to the present invention may be able to make modifications not described herein. However, if the application of these modifications to a given structure or its manufacturing process requires the material claimed in the following claims, said structures should be included within the scope of the invention.

Claims

CLAIMS Having described the invention, in the degree of authorization, it is considered as a novelty and is therefore claimed as property, what is contained in the following claims 1. Composition for cloud seeding, characterized by comprising an ionic solution of silver iodide in an organic solvent or mixture of solvents.

2. Silver iodide dispersion, for cloud seeding, characterized in that the dispersion is a nanometric organic solution, where the silver iodide is in the form of nanocrystals of around 49 molecules each.

3. Silver iodide dispersion, for cloud seeding, as claimed in the previous claim, characterized in that the continuous phase, that is, the solvent of the dispersion is a mixture of at least 1) toluene, with 2) p-xylene, 3) o-xylene, 4) 2-butoxyethanol and 5) methylcyclohexane.

4. Silver iodide dispersion, for cloud seeding, as claimed in claim 1 or 2, characterized in that toluene may be present between 16.4 and 97.9%, and that p-xylene varies between 0.7 and 50%, with respect to the final solution.

5. Silver iodide dispersion, for cloud seeding, as claimed in any of claims 1 to 3, characterized in that o-xylene is present in an amount between 1.9 and 7.7%.

6. Silver iodide dispersion, for cloud seeding, as claimed in any of claims 1 to 4, characterized in that butoxyethanol may be present between 2.7 and 9.9% and methylcyclohexane varies between 0.8 and 9.8%.

7. Silver iodide dispersion, for cloud seeding, as claimed in claim 1, characterized in that the dispersing phase consists of any type of thinner. 8- Silver iodide dispersion, for cloud seeding, as claimed in claim 1, characterized in that the silver iodide is present in an amount of 400 mg / L.