Swirl Air Nozzle

Abstract

A nozzle for discharging a swirling atomized fluid includes a vortex chamber defined in the nozzle body, a gas inlet tangentially communicating with the chamber and a liquid inlet axially communicating with the chamber wherein the liquid is mixed with the swirling gas in the chamber. An impingement member is positioned in the path of fluid flowing from the chamber having a primary impact surface in the chamber upon which the swirling mixture impinges and a secondary impact surface adjacent to, but spaced from, the nozzle discharge opening upon which the swirling mixture also impinges as it is being discharged from the nozzle.

Parent Case Text

This is a division of application Ser. No. 193,023, filed Oct. 27, 1971 now U.S. Pat. No. 3,693,886 issued Sept. 26, 1972

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to fluid nozzles and, more particularly, to nozzles for discharging a swirling finely atomized liquid.

Swirling fluid discharge nozzles have found wide application in a variety of fields in which it is desired to minutely atomize liquids. For example, such nozzles have found application in water cooling, aerating, quenching, agricultural spraying and in slurry spray drying systems. In addition, such nozzles have received wide and considerable interest in various anti-pollution devices, such as dust collectors and in the evaporative cooling and scrubbing of stack gases. Such uses are but a few of the many applications in which such swirling discharge atomization nozzles have been employed where there is a need for high fluid flow rates and fine atomization at low pressures.

The nozzle constructed in accordance with the principles of the present invention is capable of producing very fine high quality atomization at very low fluid pressures and high liquid flow rates. In nozzles constructed in accordance with the principles of the present invention, close control of spray angle may be readily achieved and the degree of atomization may be closely and accurately controlled without affecting the flow rate of the fluid through the nozzle and, conversely, liquid flow rates through the nozzle may be easily and readily modulated without adversely affecting the quality of the atomization. In the nozzle constructed in accordance with the principles of the present invention, small fluid flow passages are unnecessary which might otherwise be subject to clogging by particulate matter and other contaminates which may be present in the fluid stream and external struts or other supports are also unnecessary which might otherwise interfere with the spray pattern. The nozzle of the present invention is well adapted, both by its structure as well as the composition of materials from which it may be constructed, to resist corrosion and high temperature environments in which the nozzles may be employed. In addition, the nozzle of the present invention may be readily constructed so as to generate a sonic field in accordance with well known principles so as to enhance evaporation of liquid droplets, and the low gas flow rate and power requirements of the nozzle of the present invention make possible the use of smaller compressors or blowers for providing such gas. In the nozzle and method of atomization incorporating the principles of the present invention, not only is atomization effected by a vortical mixing action of the fluids, but in addition atomization is substantially improved by both primary and secondary impingement upon rigid surfaces of the swirling mixed fluids.

In one principal aspect, the present invention comprises a nozzle for discharging a swirling fluid having a body member defining a fluid chamber and a discharge opening. First fluid inlet means communicates eccentrically with the chamber for introducing a swirling fluid to the chamber and second fluid inlet means communicates with the chamber for introducing and mixing a fluid into the swirling fluid in the chamber. Impingement means is positioned in the nozzle upon which the swirling mixed fluid impinges and includes first impact means in the chamber between the discharge opening and the first fluid inlet means and second impact means which is spaced downstream of the first impact means adjacent the discharge opening.

In another principal aspect, the present invention comprises a method of finely atomizing liquids, which includes the steps of introducing a liquid to be atomized into a swirling mass of gas, mixing the liquid and the swirling mass of gas together to produce a swirling mixture, and impinging the swirling mixture upon a first impingement surface and thence a second impingement surface.

These and other objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWING

In the course of this description, reference will frequently be made to the attached drawing in which:

FIG. 1 is an exploded view of a preferred embodiment of swirl air nozzle constructed and which operates in accordance with the principles of the present invention;

FIG. 2 is an enlarged cross sectioned side elevation view of the embodiment of nozzle shown in FIG. 1 in assembled form; and

FIG. 3 is a cross sectioned end elevation view of the nozzle taken substantially along line 3 - - 3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of nozzle constructed and which operates in accordance with the principles of the invention comprises a substantially cubic nozzle body 10 having a vortex chamber 12 bored therein which extends axially into the body from an opening 14 through one side 16 of the nozzle body. A threaded boss 18 is also formed on another face 20 of the nozzle body. The boss 18 includes an eccentrically bored passage 22 which extends through the boss and communicates substantially tangentially with the essentially cylindrical chamber 12. The boss is suitably threaded at 24 so as to receive a suitable conduit or the like (not shown) for carrying a gas, such as air or steam, to the passage 22 from whence it it tangentially introduced into the chamber 12 such that a vortical swirling motion is set up in the chamber.

In addition, an opening 26 also communicates with chamber 12 through another side 28 of the nozzle body and a suitable liquid inlet fitting 30 is fitted into this opening and fixed to the nozzle body as by weld 32. This fitting 30 includes a liquid passage 33 therethrough and is also preferably threaded at 34 so as to adapt it for coupling to a suitable liquid supply conduit (not shown) through which the liquid, such as water, which is to be atomized by the nozzle of the present invention is introduced axially into the swirling vortical mass of gas in chamber 12.

The end of the chamber 12 adjacent opening 14 is also threaded internally at 36 to receive a threaded metering nut 38. The metering nut 38 includes an axially extending doubly tapered bore 40 therethrough which opens into a nozzle discharge opening 41. Bore 40 preferably is formed with a predetermined minimum cross sectional dimension at 42 and the bore is preferably constructed such that the bore diameter progressively increases toward the ends of the nut from the minimum diameter portion 42 thereof. Hence, it will be seen that as fluid flows fom the left to the right, as viewed for example in FIG. 2, the fluid will progressively increase in velocity as it flows through the tapered portion 44 and approaches the minimum diameter dimension 42 of the bore, and will then expand as it is discharged from the bore, the increasing taper of the tapered end portion 46 controlling the spray cone angle.

In the present invention, fine minute atomization is not only achieved by the swirling vortical mixing of the gas and liquid both in the vortex chamber 12 and the chamber passage formed by bore 40, but the quality of atomization is substantially enhanced by the provision of impingement member 48. The impingement member 48 comprises an elongate tapered pintle 50 having a flat upstream end which forms an impact or impingement surface 52 facing the vortex chamber 12. Impingement and extremely fine atomization in this primary impingement zone A, which is located between the nozzle discharge opening and inlet passages 22 and 33, is also enhanced by a plurality of radially extending arms 54 which extend outward from the flat impact surface 52. These arms 54 not only increase both the area and perimeter of the primary impingement zone A as the swirling mixture of gas and liquid flows from the chamber 12 into bore 40 and through zone A, but also are of a length such that they rest against a shouldered end surface 56 formed at the upstream end of the metering nut 38 to position the impingement member 48 in place in the assembled nozzle.

In addition, a secondary zone B of impingement is also effected by the impingement member of the present invention. This secondary zone is formed by a flat substantially circular disc 58 positioned at the downstream end of the pintle 50 so as to define an annular surface 60 which faces the discharge opening 41 of the metering nut adjacent to, but spaced downstream slightly, from the discharge opening.

It will be seen that the cross sectional annular area of the passage or bore 40 between the pintle exterior surface 62 and the side walls 64 of the bore through the metering nut 38 is somewhat smaller than the cross section of the vortex chamber 12. Hence, the velocity of the swirling mixture as it passes through this annular passage 40 will increase to further effect turbulence in the mixture which, in turn, further enhances atomization. It will also be seen that the nozzle capacity and discharge characteristics may be easily and readily varied simply by changing the cross sectional dimension of this annular passage 40 by the simple substitution of either a different metering nut having a different diameter bore or an impingement member having a different cross sectional dimension, or both, so as to vary the cross sectional dimension of the fluid flow passage through the metering nut.

Although it is believed that the operation of the present invention is clear from the foregoing description of the preferred embodiment, a brief description of the operation is as follows:

Gas, such as air or steam, is introduced to the vortex chamber 12 by way of eccentric passage 22. Since passage 22 enters chamber 12 substantially tangentially, a swirling vortical mass of gas is present in chamber 12. To this swirling gas mass, the liquid to be atomized, for example water, is axially introduced through passage 33 and is mixed with the gas in chamber 12 to produce a swirling mixture of gas and atomized liquid.

This swirling mixture then passes through primary impingement zone A where it impinges upon surface 52 and arms 54 further improving the quality of liquid atomization.

As the swirling mixture leaves zone A, its velocity is progressively increased and then the mixture is rapidly expanded as it passes through the decreasing tapered portion 44, the minimum dimensioned portion 42, and the increasing tapered portion 46 of bore 40, and is discharged through opening 41. Thereby, further turbulence and agitation of the swirling mixture is effected which further improves the quality of atomization.

Finally, the swirling mixture impinges upon surface 60 of disc 58 in the secondary impingement zone B as the mixture is discharged from opening 41 to further enhance atomization.

It has been found that in the operation of the present invention, the quality or degree of atomization of the liquid may be readily varied by controlling the gas to liquid ratio over a wide range of flow rates. Also, if the gas pressure is initially set and it is desired to modulate the liquid flow rate, the gas pressure change and flow rate will automatically respond such that atomization quality will remain substantially constant. This latter advantage of the present invention will result in equipment savings by eliminating gas valving and other necessary gas controls.

It should be understood that although air and steam have been set forth herein as suitable gases and water as a suitable liquid, that the principles of the invention are readily applicable to other gases and liquids. It should also be understood that the embodiment of the present invention which has been described is merely illustrative of one of the applications of the principles of the invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention.

Claims

What is claimed is

1. A method of finely atomizing liquids comprising the steps of:

introducing a liquid to be atomized into a swirling mass of gas,

mixing said liquid and swirling mass of gas together to produce a swirling mixture,

flowing said swirling mixture over a first impingement surface to impinge said mixture upon said surface,

flowing said swirling mixture through a passage having minimum cross section downstream of said first impingement surface to increase the velocity of said swirling mixture,

expanding the swirling mixture while flowing the swirling mixture over a second impingement surface downstream of said first impingement surface and said minimum cross section of said passage to impinge said mixture upon said second surface downstream of said minimum cross section, and

discharging said mixture from said passage adjacent said second impingement surface.

2. The method of claim 1 wherein said liquid is introduced substantially axially of said swirling mass of gas.

3. The method of claim 1 including discharging the swirling mixture from said passage and then flowing the discharged mixture over said second impingement surface.