WO2005048690A1

WO2005048690A1 - A land based generator for production of an aerosol of silver jodide particles

Info

Publication number: WO2005048690A1
Application number: PCT/SE2004/001488
Authority: WO
Inventors: Abdallah Nbou
Original assignee: Skandinaviska Meteorologi- Och Miljöinstrument Ab
Priority date: 2003-11-19
Filing date: 2004-10-15
Publication date: 2005-06-02
Also published as: OA13325A; MA28166A1; SE0303059D0; SE525076C2; SE0303059L

Abstract

A generator for producing an outwardly rising aerosol of iodide particles for creating precipitation of atmospheric moisture, wherein the generator includes a container (2) for containing a solution of iodide in a solvent in the form of fuel, wherein the solution is caused to be delivered to a combustion unit which includes a solution atomising nozzle (20), wherein the solution is ignited for combustion of the solvent and to form iodide particles for producing said aerosol, wherein there is provided a fuel container (1); wherein there is also provided a line (24) for carrying said fuel to a fuel burner (25) in the vicinity of the nozzle (20) so as to establish a flame in said generator, wherein the nozzle is adapted to introduce the atomised solution into the fuel flame; wherein there is also provided a further container (3) for containing material, particularly iodide, dissolved by combustible solvent in said solution; and wherein means are provided for periodically interrupting the supply of solution to the nozzle (20) and for supplying during these periods solvent from the solvent container (3) to and through the nozzle (20) with the intention of dissolving and removing any caked material that can have a negative effect on aerosol formation.

Description

A LAND BASED GENERATOR FOR THE PRODUCTION OF AN AEROSOL OF SILVER IODIDE PARTICLES

The present invention relates to a land based generator for the production of an upwardly rising aerosol of iodide particles so as to create atmospheric precipitation, said generator being of the kind defined in the preamble of the accompanying Claim 1.

FR-A-2267696 discloses a generator of the kind in question. A silver iodide solution in a solvent that constitutes a flame-burning fuel is transported from a solution tank to a burner, where the solution is ignited to form a flame. A stream of air is led past the flame and receives silver iodide particles generated in the flame so as to form a particle aerosol which is allowed to rise up into the atmosphere. The particles form condensation nuclei for reaction with atmospheric moisture such as to create atmospheric precipitation/rain in the area concerned.

One problem with generators or engines of this kind, however, is that material, for instance silver iodide and sodium iodide, intended to form the iodide particles and dissolve in the combustible solvent, for instance acetone, has a tendency to settle in the form of a material cake in the passage of time, therewith impeding the outflow and spreading of the solution spray in the burner of the generator. This can also have a negative effect on the flame. The fuel flame may also die out. Any cake that is formed should be removed. This may present a serious problem, since generators of the kind concerned are seldom placed in readily accessed geographical positions, i.e. positions in which no operators for such maintenance work are readily available. It should also be possible to readily re-light an extinguished flame.

Accordingly, one object of the present invention is to provide a generator with which the aforesaid problem is solved either completely or partially.

This object is achieved by means of the present invention.

The invention is defined in the accompanying independent claim. Further embodiments of the invention are defined in the accompanying dependent claims.

According to the present invention, the generator includes a fuel storage means which is adapted to establish a burning flame from a fuel supply, wherein the solution is introduced into the flame as a back-up thereto, wherein the solvent storage includes means for selective supply of the solution to the burner unit; wherein there is provided a store of combustible solvent, said store including means for selective supply of solvent to the burner unit, and wherein the solvent constitutes a solvent for the material dissolved in the solution. Means are provided for periodically interrupting the supply of solution to the spray nozzle and initiate a flow of solvent from the solvent store to and through the burner unit such as to dissolve any deposits of flame disturbing material. The solvent is introduced into and combusted together with the fuel flame. Because the solvent that removes cake deposits is combusted in the flame, the risk of the outflowing solvent harming or negatively affecting the surroundings is reduced. The generator may also include automatic ignition means which is controlled by a flame sensing guard that functions to light the flame or to re-light the flame should said flame have been extinguished, provided that the flame guard is activated.

An exemplifying embodiment of the invention will now be described in more detail with reference to the accompanying drawing.

Figure 1 is a diagrammatic illustration of a generator constructed in accordance with the invention.

The fig. 1 illustration includes a fuel container 1. The fuel may consist of propane, for instance. Also shown is a container 2 for a solution of one or more metal iodides, for instance silver iodide, and a metal iodide solvent, for instance acetone. The solution may also contain sodium iodide. Also shown is a container 3 that contains a solvent for those materials dissolved in the solution in the container 2.

Also shown in figure 1 is a chimney pipe 10 which include in its lower part an inlet for an air flow 11. Located at the bottom end of the chimney 10 is a spray nozzle 20 that can be connected either to the tank 3 or to the tank 2 via a respective line 23 or 22. The lines 22, 23 open out at the bottom part of a respective tank 2, 3. The lines 22, 23 include a respective valve 33 and 32 which allow respective lines 23 and 22 to be closed and/or the flow through respective lines to be controlled. A fuel container 1 includes an outlet line 24 which connects with a fuel burner 25 in the lower part of the chimney 10. The line 24 includes a regulator valve 26 and a closure valve 28 nearest the container 1. A branch line 41, 42 extends from the line 24 to the top space of the closed containers 2, 3. The lines 21, 22 may include regulating valves for setting a selected pressure in the top spaces of the containers 2, 3, for driving the content of the containers 2, 3 to the nozzle 20.

As shown, the chimney 10 also includes a flame detector 60 and a flame igniter 62.

Control means are also provided for controlling the operation of the generator.

It can be assumed that the flame detector 60 is activated and that when failing to detect a flame the igniter 62 will deliver sparks or a corresponding emission for igniting combustible material that exits through the fuel nozzle 25 or the nozzle 20. The flame guard 60 may be designed to deactivate the igniter 62 when detecting a flame.

The valve 28 is opened and the valve 26 is set to a position in which fuel is fed from the container 1 to the nozzle 25, when the flame guard 60 is activated. The valve 32 is also opened, so that silver iodide and sodium iodide solution passes through the line 22 and the nozzle 20 so as to form a spray which is combusted together with the fuel from the nozzle 25. This results in an aerosol of silver iodide particles that flows up through the chimney 10 and from there to elevated levels where there is found moisture that is able to condensate on the condensation nuclei formed by the silver iodide particles and therewith form both small and large droplets of water that will hopefully fall as rain onto the surrounding ground.

There is a tendency for silver iodide and sodium iodide to cake on the nozzle 20 in the close vicinity of the nozzle outflow opening. This caked iodide material can have a negative effect on the spray exiting from the nozzle 20. This will also interfere with the production of the silver iodide aerosol. There is also a danger of the nozzle 20 being blocked. The fuel fetched from the tank 1 and combusted in the burner 25 promotes an outwardly rising flow of warm or hot air that entrains the iodide particles.

Because the solvent used in producing the solution also constitutes a fuel, the flame detector 60 is able to detect disturbances in the resultant flame. These disturbances can eventually be interpreted as meaning that the nozzle 20 needs to be freed from an iodide cake. The flame guard 60 can then close the valve 32 for a predetermined period of time and open the valve 33 for the same time period, so that solvent from the container 3 will flow through the line 23 and through the nozzle 20. The solvent is able to dissolve the caked material, and the solvent spray will be combusted together with the fuel that exits through the fuel nozzle 25. Because the solvent emanating from the tank 3 is combusted, contamination of the surroundings or the creation of fire risks and explosion risks by the solvent 3 is prevented.

At the end of the pre-set time period mentioned above, the guard 60 or some other corresponding control means will close the valve 33 and open the valve 32 so as to restore production of an aerosol.

The present invention also reduces the risk of disturbances in generator operation.

The overall operation of the generator can be controlled typically in a wireless manner, via telephony, for instance via satellite telephony with regard to operating periods and the like.

It has been said in the above description that a flame guard is used to detect any disturbances in operation caused by caking of material, e.g. on the nozzle 20. It will be obvious, however, that by way of an alternative the supply of solution and solvent respectively to the nozzle 20 may be controlled with the aid of some other control means 70, for instance a timer, that is able to control the valves 32, 33 for instance, wherein the supply of iodide solution is interrupted periodically, for instance for 5 minutes every hour, once solvent is fed from the container 3 to the nozzle 20 over this time period. In addition to dissolving any material that has caked on the nozzle, the solvent can be injected into and combusted in the fuel flame established by the burner 25 with the aid of fuel taken from the tank 1. The fuel flame is monitored by the flame guard 60. This variant of the invention also affords the important advantage of reducing or removing any material that has caked on the nozzle 20 whilst burning the combustible solvent at the same time, by virtue of the solving spray exiting from the nozzle 20 coming into contact with the fuel flame established by the burner 25. Caked iodide dissolved and entrained by the solvent is then able to form the desired particles. The fuel flame establishes a flow of warm or hot air that contributes towards establishing the aerosol and causing the aerosol to rise.

Claims

1. A generator for producing an outwardly rising aerosol of iodide particles for creating precipitation of atmospheric moisture, wherein the generator includes a container (2) for containing a solution of iodide in a solvent in the form of fuel, wherein the solution is caused to be delivered to a combustion unit which includes a solution atomising nozzle (20), wherein the solution is ignited for combustion of the solvent and to form iodide particles for producing said aerosol, characterized in that there is provided a fuel container (1); in that there is also provided a line (24) for carrying said fuel to a fuel burner (25) in the vicinity of the nozzle (20) so as to establish a flame in said generator, wherein the nozzle is adapted to introduce the atomised solution into the fuel flame; in that there is also provided a further container (3) for containing material, particularly iodide, dissolved by combustible solvent in said solution; and in that means are provided for periodically interrupting the supply of solution to the nozzle (20) and for supplying during these periods solvent from the solvent container (3) to and through the nozzle (20) with the intention of dissolving and removing any caked material that can have a negative effect on aerosol formation.

2. A generator according to claim 1, characterized by a flame guard (60) adapted to detect the presence of a fuel flame, and by ignition means (62) which functions to create a flame when the flame guard is activated but no flame can be detected.

3. A generator according to claim 2, characterized in that the flame guard (60) is adapted to detect a disturbance in the resultant flame created by the solution and the fuel and to cause a temporary interruption in the supply of said solution on the basis of said detected disturbance and to cause solvent to flow from the solvent container to and through said nozzle during this period of interruption.

4. A generator according to claim 1, characterized by timer means (70) for interrupting the supply of solution to the nozzle (20) over chosen time periods and for causing solvent to be delivered to the nozzle over said chosen time periods.