US 3078047 A
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3,073,047 LOW PRESSURE ATGMHZER NOZZLE FGR OL BURNERS Arne Fromm Enernarir, Sonderhorg, Denmark, assignor to Danfoss VE?) ingenior Mads Clausen, Eismark, Nordborg, Denmark, a Danish firm Filed dan. 2, 1957, ser. No. 632372 Ciainras priority, appiicaton Denmark Mar. 21, 1956 3 Ciainrs. (Cl. 239-405) The invention relates to a low pressure atornizer noZZle for oil burners and with a central oil feed pipe and primary air feed passages surrounding the said oil feed pipe and opening into an atomizer head from which tangentially disposed guiding passages emanate into which feed openings from the Oil feed pipe open in order to produce a whirling motion and simultaneous atomization of the oil in an air stream having preferably conical surface and issuing from an atomizer opening provided centrally in the front face of the nozzle.
Low pressure atomizer noZZles of the aforesaid kind are known, but they suffer from the drawback that they are apt to give an irregular atomization when fed with reiativeiy small amounts of oil, since the oil fed is liable to be divided into dreps instead of issuing as a continuous stream, and these discontinuous drops will involve a pulsating atomization with consequent irregular combustion and precipitation of non-atornized oil drops on the inner surfaces of the Oil-firing installation.
It is the obiect of the invention to devise the construction of a low pressure atomizer nozzie having none of the aforesaid drawbacks, and an essential feature of a low ressure atemizing nozzzle according to the invention is that between the oil feed pipe and the air feed passages there is provided a preferably cylindrical body, coaxial with the axis of the nozzle, the said cylindrical body being made of a material that is permeable to the primary air, such as porons metal.
As a result, the primary air from the air feed passages penetrates the porous body and mixes with the amount of oil supplied through the Oil feed pipe so as to form a frOth-iike mixture. The said mixture is then, partly by eiector action of the air in the tangentiaih disposed guiding passages, partly by the pressure exerted by the air in the air feed passages, passed as a continuous flow to the atomizing opening of the noZZle, where the mixture is effectively atomized without any tendency to drop formation with its consequent inconveniences.
According to the invention the porous body is detachabie and mounted between the atomizing head of the noZZie and a sleeve which is provided with the air feed passages and constitutes a part of the oil feed pipe.
As a result, the porous body may be exchanged and, if necessary, cleaned in case its pores should be more or iess ciogged by impurities contained in the oii.
According to the invention the porous body has conical sealing snrfaces facing both the atomizing head and the sieeve.
As a result, the porous body is Centered soieiy by the cone-shaped surfaces resting in contact with the said parts of the noZZle.
According to the invention such surface of the porous body as faces the air feed passages or a pressure Chamber formed hy a widening of these is slightly truncated, having its largest diameter close to the atomizing head.
As a result, the cross-section of the space between the surface of the porous body and the air feed passages is narrowed in the direction towards the atomizing head, which affords an adaption of the amount of air which is decreasing along the surface of the porous body because of the partial air penetration through the said porous body.
&078347 Patented Feb. 19, 18 53 Furtherniore, the surface available for the air penetration will be increased in such an embodiment.
According to the invention the central passage of the porous body has its largest diameter close to the atomizing head.
As a result, suction will be'produced by the oil flow through the central passage owing to this increase in diameter.
According to the invention the central passage of the porous body opens into a mixing Chamber which is formed in the atomizing head and is of greater diameter than the central passage.
As a result, a turbulent flow of the froth-like oil/air' mix is produced at the place where the central passage joins the mixing Chamber, and the said flow increases the frothing in effective manner and reduces the size of the air bubbles incorporated in the emulsion.
According to the invention the mixing Chamber is along the circurnference of its inner wall provided with feed openings directed obliquely outwards to the tangentially directed guiding passages.
As a result, the oil/air mix flowing from the central passage cannot be pressed directly out through the feed openings, but, on the contrary, its central parts are intercepted by the end wall of the mixing Chamber opposite the central passage, whereby the turbulence of the mixture is further increased. At the same time the distance for the mix in the tangentially disposed passage is' increased, which stabilises the direction of the spray in the conical air stream outside the atomizer opening.
According to the invention the surface of the end wall in the mixing Chamber is convex and preferably of conical shnpe, which also increases the turbulence of the flow in suitable manner.
The invention will now be further described with reference to the drawing, in which FIGURE 1 is a diametral section of a low Pressure atomizing nozzle according to the invention,
FGURE 2 is a section at right angles to the axis of the nozzle on the line 11-11 of FIGURE 1, and
FIGURE 3 is a section of same, at right angles to the aXis of the noZZle on the line ilL-iil of FIGURE 1.
The low pressure atornizing nozzle 1 shown in the drawing has a central oi-i feed pipe 2 and a number of surrounding feed passages 3 for primary air which open into an atomizing head 4 from which emanate tangentially directed guiding passages 5 in which feed openings 6 from the oil-feed pipe 2 open. The fuel oil, which is fed to the oil-feed pipe 2 at a relatively low pressure, flows through the feed openings 6 into the guiding passages 5 where it meets in a conical mixing dome, the primary air supplied through the passages 3, whereby the oil is subjected to a whirling motion simultaneous atomization, so that a conically shaped air-oil stream is produced, issuing from the atomizer opening '7 provided centrally in the front of the nozzle. Between the oil feed pipe Z and the air feed passages 3 there is according to the invention provided a preferably cylindrical body 8 which is coaxial with the axis of the noZZle and is made of a material that is permeable to the primary air, such as porous metal. The primary air is thus able to pass from the air feed passages 3 through the porous metal and into the oil feed pipe 2, where the air will cause the formation of a frothlike rnixture of air and oil, the said mixture being subscquently, by reason of the ejector action of the air stream in the guiding passages 5 in combination with the pressure exerted by the air from the air feed passages 3 and the pressure exerted by the oil from the Oil-feed pipe 2, passed as a continuous stream to the atomizer opening 7 of the nozzle. In the atomizer opening of the noZZle the rniXture is effectively atomized without any tcndency to drop formation With its consequent inconveniences.
The porous body 8 is exchangeable and mounted between the atomizer head 4 and sleeve 9 in which the feeding passages 3 for the primary air are provided and which constitutes a part of the oil feed pipe 2, the porous body having conical sealing surfaces 10 and 11 facing the sleeve 9 and the atomizer head 4, respectively. The porous body 8 is Centered in the cavity Of housing l by the :aling surfaces so that an air pressure Chamber 12 is defined in the cavity between the outer surface of the porous body 8 and the air-feeding passages 3. The surface of the body S which faces the pressure Chamber is slightly truncated, having its largest diameter close to the atomizer head 4. Similarly the central passage 13 of the porous body 8 has its largest diameter close to the atomizer head 4, and where the latter joins the central passage 13 the atomizer head is formed with a mixing Chamber 14 which has a larger diameter than the central passage 13. Along the circumference of its inner wall the mixing Chamber 14 is provided with feed Openings 6, directed obliquely outwards and ending in the guiding passages 5. The end wall surface 15 in the mixing chamber is preferably conical.
What I claim and desire to secure by Letters Patent is: 1. A low pressure atomizer nozzle for oil burners comprising a hollow housing defining an interior cavity and having a forward wall provided with a central discharge opening, a central oil feed-pipe element disposed at least partially in said cavity and provided with means defining primary air feed passages surrounding said element and communicating with the portion of said cavity between said element and said forward wall for the passage of air under pressure into said cavity portion, an atomizer head in said cavity adjacent said forward wall and disposed to receive Oil feed interiorly from the interior of said element, said atomizer head being formed with feed openings for passage of Oil therethrough and tangentiallydisposed guiding passages communicating with said feed openings, land a porous channel-ferming member disposed between said feed-pipe element and said atomizer head, said body being coaxial with the axis of the nozzle and being formed from a material which is permeable to the primary air in said pressure Chamber to define a continuous oil conducting passageway between said feed-pipe element and said atomizer head, said atomizer head and said porous member being dimensioned to leave at least One peripheral pressure Chamber in said cavity porton for axial flow of said air under pressure over the exteriors of said head and said porous body and space being provided between said atomizer head and the interior of said forward wall for passage of said air from said Chamber across said passages and out said discharge opening.
2. A nozzle as defined in claim 1, wherein the porous member has conical sealing surfaces facing the atomizer head and the feed-pipe element, respectively.
3. A nozzle as defined in claim 1, wherein the surface of the porous member which faces the pressure Chamber is slightly truncated, having its largest diameter close to the atomizer head.
4. A nozzle as defined in claim 1, wherein said porous member defines a tapered centrally-disposed channel having its largest diameter close to the atomizer head.
5. A nozzle as defined in claim 4, wherein the central passage of the porous body opens into the atomizer head defines a mixing Chamber communicating with the channel of the porous member and having a larger diameter than said channel.
6. A nozzle'as defined in claim 1, wherein said feed openings are directed obliquely outwardly in a radial direction in relation to the axis of said housing.
7. A nozzle as defined in claim 5, wherein the end surface of said mixing Chamber defined by said atomizer head is convex.
8. A nozzle as defined in claim 5, wherein the end surface of said mixng Chamber defined by said atomizer head is Conical.
References Cited in the file of this patent UNITED STATES PATENTS 674,351 Atkins May 14, 1901 2,044,720 Fletcher June 16, 1936 2,772,120 Olson Nov. 27, 1956 2,815,069 Garraway Dec. 3, 1957 2,825,602 Rabbitt Mar. 4, 1958 2,854,285 Barton Sept. 30, 1958 FOREIGN PATENTS 585,595 Germany Oct. 7, 1933 UNITED STATES PATENT OFFICE 'CERTIFICATE OF CORRECTION Patent Non &078 047 February 19, 1963 Arne Fromm Enemark Inthe grant, (Only) line l, for "Arne Fromm, of Enemark, Sqndrborg, Dnmark," read Arne Fromm Enemark of sonderb orgv Denmark,
Signed and sealed' this 3rd day of 'september l93 (SEAL) Attest:
ERNEST w. SWIDERY 'I DAVID L. LADD Attestng Officer Commissioner Of Patents