US2642150A - Apparatus for obtaining aerosols of superior quality - Google Patents

Description

June 16, 1953 .L. DAUTREBANDE 2,642,150

APPARATUS,FOR OBTAINING AEROSOLS 0F SUPERIOR QUALITY Filed Oct. 4, 1946 INVENTOR LUCIEN DAUTREBANDE BY WEWW Fm,

ATTORN EYS Patented June 16, 1953 APPARATUS Fion- OBTAINING AERO-SOLS OF SUPERIOR QUALITY Lucien Dau'trebande, Brussels, Belgium, assignor to Aerosol Corporation ofv America, New York, N. Y1, a. corporationofDelaware' Application Qctobet 4, 1946, Serial'No. 701,216 In Belgium October 5, 1945' 3 Claims. 1

The present invention relates to an apparatus for obtaining aerosols of superior, quality inwhicha liquid is vaporized or atomized by means of a gas underincreased-or-reduced pressure, and more particularly to an apparatus for atomizing a liquid in which a cloud or jet of colloidal liquid particles is passed through aliquid layer, whereby aerosols of great uniformityof size and stability are obtained, and especially to apparatus for producing aerosols'wherein the average: particle size or diameter of the dispersed'li quid particles is below one micron.

The aerosols which are produced, using the apparatus of the present invention, are of a special type and. can be considered as clouds.

. 2 ing great stability penetrate into the final atmosphere; a

of a dispersed liquid phasein a continuous gaseous phase, which have the following. characteristics:

1; Independently of the nature of the sub-' stances dispersed, a given volume of aerosols contains a given number of particles for an aqueous saline solution. of the same concentration.

2. Thisnumber of particles'increases asthe saline solution is diluted: and can-exceed; 60,000 per cubic millimeter.

3. The quantity of solution present-per cubic millimeter of aerosolsis. always the same for a,

particular apparatus, regardless ofthe nature of:

the dissolved substances: and, the: thereof. in the mother liquor.

Two important factors are thequantity of par.- ticles emerging per unit time from the liquid, and more especially their quality, i. e., their: characteristic of uniformity and stability. 7

The present invention" relates to the-quality? factor and has as its-object the productionof concentrations aerosols of great uniformity of size and stability,

the stability being conditioned'bythe small dimensions of the particles (below one micron) and by the uniformity of their size.

Ehe' majority of known apparatuses, and particularly those based on mechanical filtration, do not permit anylimiting: of the-intensity of the-mist'em-itted and donot'guarantee that'all the particles will ,havean adequate: stability.

1 tion.

Also in known apparatuses, using mechanical.

filtration,- no selection lS-POSSibIGEbEtWBGH light.

emission and increased emission.

In accordance with the" present invention, the foregoing disadvantages are overcome by passingthe cloud containing the liquid particles: across a continuousliquid layer in such amanner that-the oondensable particles of liquid are either retained by the liquid layer orare returned to ='-the mother solution and I only particles hav v -permit the -formation .of .a'spray. of liquid; (which be reformed in a continuousmanner from the liquid and provides afiltering' agent for physical selection, not permitting the passage of particles which have not attained the desired stability.

The aerosols obtained by using the apparatus of the invention havenumerous practical applications, amongwhich are the introduction of medicaments with a local pulmonary action or a general action after penetrating the lungs, hygienic precautions, atmospheric conditioning, dust removel, moisteners for threads, fabrics, stationery, and the like, and progressive moistening of vegetable and animal fibres; The apparatus is also suitable for producing fine emulsions of all kindsand of all liquids, such as oil emulsions, medicaments, and thelike.

In the apparatus of the invention the gas used may bea compressed gas, but the-apparatus may alsobe used when the system is under reduced pressure, 1. e., the interior'of the apparatus is at a lower pressure than the inlet gas.

An additional advantage in the apparatus of the invention is that the liquid filtering elements have a continuous character, which ensures complete filtration because the dispersed and condensed particles must contact a non-dispersed phase.

The invention will befurther illustrated by referenceito the accompanying-drawings in which:

Figure l is a' diagrammatic longitudinal sectional view in elevation of an apparatus for producing aerosols in accordance withtheinvention Figure-.2 is a diagrammatic transverse sectional view of theapparatus of Figure 1, and

Figurez3vis: a sectional view in elevation of an atomizingjet .used inthe apparatus of. the inven- Figures 11,2.and;3irela-te to a particularly simple: construction providing for three separate stages of-selection. It is formed of a body, such as a cylindrical vessel, inwhich there is arranged co-axially a casing, the top of. which constitutes a breaking surface for the air liquid mixture emitted from one ormore atomizers and is spaced from the' atomizers. by a.. distance sufii'ci'ent to 3 acts as a first discontinuous turbulent liquid selection layer) and a continuous liquid film due to the particles striking this surface. The vertical wall of the surface of the casing is apertured and gives rise along its interior surface to the formation of a continuous liquid film, the uniformity of which is maintained on the one hand due to the liquidparticles ascending from the Vaporizers, and on the other hand from the particles which have not acquired the necessary degree of stability and which go backtowards the mother liquid after having struck the breaking surface.

This apparatus comprises an envelope formed or" a tubular member I31 which engages'in the upper part of a base E32 having a collar I32 of slightly larger diameter in which the bottom of the member 13! can be located by projections or a screw thread (not shown) arranged horizontally around the base i32. 7

Within the member I32 are arranged a series of atomizers which in the example shown are three in number and each of which is formed (Fig. 3) of a tube i3?) dipping into the liquid and surrounded by a sheath l3? through which air is conducted, which sheath is screwed to the lower part of the tube tile. The whole is secured by a collar Hi3 having a jointing member Md. The top of sheath 531 forms a passage ite for the compressed air and the tops of the two elements 38 and i3? form a nozzle The compressed air is fed to the atomizer by means of a tube ME] (Figs. 1 and 2) leading to a sphere E li which in turn is connected by tubes with the Vaporizers 133, !34, anditll.

The top of. the member it! forms an exit chimney its for the aerosols. A perforated cylindrical casing M6 is fitted tightly at its base in member iiii by means of a collar or flanged 1 portion it? and is supported in position at the top by means of horizontal stays I48 which extend to the member I31.

In the example shown the position of the top Hi and consequentlythe distance which separates it from the jets can be regulated easily as the lateral stays 1 33 are in sliding contact with the member. iSi. Any other regulating means such as springs, hooks, etc. can be provided for this purpose.

The openings me in the casing M8 permit the passage of aerosols to the space I59 between the members i 53 and Isl, from which they pass to the exit chimney. The end of easing I46 is closed by member ll, which constitutes a breaking surface as will be described below.

In using such an apparatus, the discharge from each atomizer {33, 34, I35 and the distance between the nozzles !39 and the surface 254 are adjusted so as to produce within the sheath [46 a dispersion of the liquid particles in the formv Or" a spray, which constitutes a liquid turbulent discontinuous layer which the particles must necessarily traverse as soon as they are emitted.

Simultaneously, there is formed along thein-- terior cylindrical wall of the casing I45, a liquid continuous film by the ascending particles, which covers the openings i 39 as soon as the atomiza tion commences. Furthermore, the vertical jets strike the horizontal member |5l and result in the formation on this surface of a thick continuous liquid film. This liquid film functions as a liquid filter in such a way that the partielse which have not acquired the requisite degree of stability to traverse it 'go back towards 2,642,160 1;": Y I. .1 f

the mother liquid and give rise, along the interior surface of the casing, to a descending continuous film. The cooperation of the continuous ascending film and descending film results in the lateral liquid film remaining substantially of the same thickness. I r

. There are thus four liquid filtering zones; one discontinuous and three continuous forming four successive stages of selection: (1) The column or vertical spray formed in the space within the casing I 36 by the jets issuing vertically from the Vaporizers I33, its, and I35. The height and the dispersion of this spout are regulated by the position of the casing M6. (2) The continuous turbulent film formed by the spray striking the have given them the necessary stability to permit them to pass through the continuous film covering the interior surface of the casing Hi6.

In order to improve filtration by the ascending and descending films it is advantageous to arrange that the lateral apertures 549 have a rounded edge, which may be regular or irregular, towards the interior of the sheath.

The thickness of the upper liqui'dlayers and the ascending and descending liquid layers can 'be regulated eitherbyvarying the amount or" atomization or number of nozzles or by varying the height of thesheath Hit or by moving the top l5! towards or away from the nozzles. In this way it is possible to modify not only the quantity but also the quality of the particles emitted.

I claim:

1. An apparatus lor producing aerosols of en perior quality comprising a closed vessel contain ing an atomizing means including a gas inlet tube and a liquid feed tube terminating near the bottom of the vessel, an aerosoloutlet tube having a discharge opening therein and an apertured cylindrical enclosure vcoaxially disposed within said vessel and said outlet tube and positioned between the atomizing means and said discharge opening and arranged across the path of the cloud formed by, said atomizing means, said enclosure being enlarged near its lower end so as to ,fit snugly against the outer wall of the cylindrical vessel at a point near the outlet tube, the end of said enclosure being closed and the cylindrical walls of said enclosurebeing apertured.

2. An apparatus in accordance with claim 1 wherein the apertures in the cylindrical enclosure let tube and positioned between said atoinizing 7 means and said discharge opening and separating said vessel from said outlet tube, said enclosure having an inner open end communicating with said vessel and an outer closed end extending across the path of the aerosol cloud formed by said atomizing means and perforations in its side walls for passage of the aerosol cloud to said outlet tube and flow of condensed liquid back from said tube into said vessel.

LUCIEN DAUTREBANDE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 321,338 Burk June 30, 1885 464,779 Reichhelm et a1 Dec. 8, 1891 740,714 Titus Oct, 6, 1903 Number Number

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