US2374290A - Adjustable liquid fuel burner - Google Patents

Description

April 24, 1945 I J. E. JoHANssoN 2,374,29@

ADJUSTABLE LIQUID FUEL BURNER Filed Jan. l5, 1943 Patented Apr. 24, 1945 ADJUSTABLE LIQUID FUEL BURNER Johan Erik Johansson, Goteborg, Sweden, as-

sig'nor to Aktiebolaget Gotaverken, Goteborg, Sweden, a corporation of Sweden Application January 13, 1943, Serial No. 472,243 In Sweden February 12, 1942 1 Claim.

the shield. However, in conventional` liquid fuel burners which are at present available the fuel flows out of the atomizer in the shape of a thin layer limited by two conical surfaces having a common apex. 'I'he difference between the apex or top angles of said surfaces is very small and, therefore, it is very diflicult to bring about a continuous control of the fuel quantity delivered to the combustion zone.

. The principal object of the present invention is to provide means to render possible a very exact continuous control of the fuel quantity supplied by an oil burner to a combustion zone.

This and further objects are attained by mechanism illustrated in the accompanying drawing, in which- Fig. 1 is a longitudinal section of a burner constructed in accordance with the invention;

Figs. 2, 3 and 4 illustrate various details of the burner; and

Fig. is a longitudinal section of a complete burner assembly.

The burner according to Figs. 1-4 comprises a pipe I for supplying liquid fuel to the atomizer proper. Said pipe is movable in longitudinal diwhich consists of a drum 2 in the shape of a truncated cone. At the base of the cone the drum is provided or connected with a hollow stem 3 in which the pipe I is movable. The drum 2 which may be rotatable is provided near the base portion with bores 36 for withdrawing fuel caught by the shield from the drum. At the small open end of the drum through which the fuel is thrown by the atomizer, the drum is provided with a sharp circular flange 5 limiting the fuel outlet of the burner. At the end of the pipe I extending into the drum 2, there is fixed an atomizer consisting of three diaphragme 6, 1 and 8 disposed co-axially to and behind one another. These diaphragms are shown in Figs. 2-4 in the same order as they are disposed in the atomizer from the right to the left in Fig. 1, that is, in the direction of ow of the fuel. A collar 8 screwthree diaphragms 8, 1, 8 and holds the diaphragms together by pressing them against the end of the pipe I. The diaphragm 6 is a distribution diaphragm provided with a number of longitudinally disposed bores I0 for distribution of the liquid fuel supplied by the pipe I to slots provided in the subsequent diaphragms 1 and'8. In the embodiment shown, there are eight bores in the diaphragm 6, but the number of the bores may obviously be varied. The bores I0 conduct the fuel to an annular groove Il provided in that side of the next following diaphragm 1, which faces the diaphragm 6. The annular groove II is through tangentially disposed ducts I2 connected with a central whirling chamber I8 from which a central outlet duct or nozzle I4 extends through the diaphragm in a direction towards the opening of the burner. The diaphragm 1 is further provided with four axial bores I5 connecting the groove I I with a similar annular groove I6 in the diaphragm 8. Tangentially disposed ducts I1 extend from the annular groove I6 to a central whirling chamber I8 in the diaphragm 8, into which chamber also the nozzle I4 opens. A central duct or nozzle I9 having a larger cross-sectional area than the nozzle I4 extends through the diaphragm 8 and constitutes an outlet for the fuel from the atomizer.

Due to the illustrated arrangement of two nozzles Il and I9 disposed co-axially one behind the other, the fuel jets obtain the shape of two hollow concentric cones 2D and 2I. By suitably adapting the dimensions of the grooves and bores in the diaphragms 1 and 8, it is possible to bring about that the jet cones 20 and 2| nearly continuously adjoin each other and form a single hollow cone limited by two conical surfaces having considerably diilerent-l top or apex angles. However, practically there is never any interspace between the two cones, as is shown in Fig. l, due to the fact that the fuel particles of the inner cone, which have a greater rotational velocity than the particles of the outer cone, will withdraw particles from the latter so that the cones will continuously adjoin each other.` The length 22 of the section line between the hollow jet cones 20, 2| and the limiting edge 5 of the shield indicates the principal range in which a displacement of the shield and the atomizer relatively to one another effects a variation of the fuel quantity delivered to the combustion zone. In the embodiment illustrated in llg.V 1, this length 22 is about half an inch at a diameter of the opening in the shield of about two inches. Thus, the displacement ofv the threaded onto the end of the pipe I encloses the atomizer and the shield relatively to each other can be limited to this value. In the position of the atomizer and the shield illustrated in the drawing, evidently the maximum quantity of fuel is delivered to the combustion zone. When the pipe I is displaced to the right in Fis. l relatively to the drum 2 the quantity of fuel delivered to the combustion zone is continuously reduced. After the atomizer has been displaced the length 22 the main portion of the fuel flowing out of the atomizer is caught by the flange and will return through the bores 38 to the fuel tank. It is evi dent that by using an atomizer producing a single hollow Jet cone it would be necessary to have the entire control of the fuel quantity from maximum to minimum be enected by a displacement over a range 23 or 24, the length of which, however, is very small, namely, about a quarter of an inch only, s that an exact control of the fuel quantity would be rendered very dimcult.

Fig, 5 is a longitudinal sectionv of a complete burner assembly according to the invention. The atomizer 28 is of the same type as the atomizer illustrated in Figs. 1-4 and is mounted on a tubular shaft 28 movable in longitudinal direction by means of a hand lever 21 and levers 28, 29, 30. The levers 29 and 30 are journalled on a pivot 3| and the rounded end of the lever 30 is guided in an annular groove 32 at the right hand end of the shaft 28. Liquid fuel is conducted to the atomizer through the tubular shaft 28 by means of a pump mounted in a housing 33. The atomizer is surrounded by a rotating drum 34 having a limiting flange 36 which forms the shield proper for catching a portion of the hollow Jet cone from the atomizer. The drum 35 has the shape of a truncated cone and is provided at its base with bores 38 through which fuel caught by the drum flows into a housing 31 enclosing the drum. From said housing 31 fuel in excess is drained off through a pipe 38. The drum 34 is mounted on a tubular shaft 39 Venclosing the shaft 28 and rotating on the latter. The shaft 39 is Journalled in the housing 31 and also in the rear wall 49 of the housing 4I for the burner assembly. On the housing 4I is mounted an electrical motor 42 which by means of wedge-shaped belts 43 drives the tubular shaftl 39 to which the fuel pump is connected. A fan or blower 44 secured on the shaft 38draws in combustion air through openings 45 in the cylindrical rear portion of the hous, ing 4| and blows said air into the combustion zone. A slide 48 for controlling the quantity of combustion air is disposed in the cylindrical portion of the housing and can be adjusted in longitudinal direction by means of a rod 41 and a lever 48 operable by the hand lever 21. The slide consists of a body of revolution disposed co-axially with respect to the fan 44 in front of the inlet of the latter. The openings 48 taper towards their ends 49 turned to the fan so that by displacement of the slide to the left in Fig. 5 from the position illustrated in the drawing the inlet area for the air will at first be relatively slowly reduced but towards the end of the displacement in said direction relatively more rapidly. By suitably forming the openings 48 and by interconnecting the fuel controlling means and the means for controlling the quantity of air delivered to the combustion zone, a proper relation between fuel and air quantity can be obtained at varying loads. The device described for controlling the air quantity may obviously be used in combination with burners of other construction than that illustrated in Fis. 5.

The embodiments of the invention described above and illustrated in the drawing should only be considered as examples, and the details thereof may obviously be modified in various ways within the scope of the following claim.

More than two nozzles may for instance be mounted behind one another in the atomizer so that more than two coaxiaily disposed hollow let cones are obtained and, consequently, the range of control is further increased. Atomizers may also be used, in which different groups of tangentially directed grooves are adapted to supply fuel to a whirling chamber, so as to obtain concentrically disposed layers of fuel whirling with different velocities. 'I'hus, when such layers of fuel are flowing out of a central nozzle, they give rise to different jet cones coaxially disposed to each other. The displacement of the atomizer relatively to the shield can naturally be effected in different ways. The shield may, for instance, be movable and the atomizer'stationary. The means for controlling the fuel and air quantities delivered to the combustion zone may be automatically adjustable by means of a thermostatlc device varying the adjustment ci' said means in response to the temperature in a boiler, the air in a room or the like impulse. 4

What I claim is:

In a liquid fuel burner, a fuel atomizer, means in said atomizer for spraying fuel supplied' to said atomizer in at least two hollow iet cones disposed concentrically to each other, fuel catching means disposed adjacent to the path of the fuel jet delivered by the atomizer and adapted to catch portions of said fuel Jet and to prevent caught fuel from entering the combustion zone of the burner, and means to effect a 4displacement of said fuel catching means and said atomizer relatively to each other a length corresponding to the distance from the section line between said fuel catching means and the exterior envelope of the largest one of said jet cones to the section line between said fuel catching means and the interior envelope of the smallest one of said Jet cones.

JOHAN ERIK JOHANSSON.

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