US2762655A

US2762655A - Variable output burner for liquid fuel with pressure pulverization

Info

Publication number: US2762655A
Application number: US347780A
Authority: US
Inventors: Charasse Auguste Francois
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-05-13
Filing date: 1953-04-09
Publication date: 1956-09-11
Anticipated expiration: 1973-09-11

Description

Sept. 11, 1956 A. F. CHARASSE 2,7

VARIABLE OUTPUT BURNER FOR LIQUID FUEL WITH PRESSURE PULVERIZATION Filed April 9, 1953 Ewen 1 R Hugus r: Emma (imzznsss a/m 1 W VARIABLE OUTPUT BURNER FOR LIQUID FUEL WITH PRESSURE PULVE'RIZATI'ON Auguste F rangois Charasse, Marseille, France Application April 9, 1953, Serial No. 347,780

Claims priority, application France May 13,1952.

2 Claims. ((11. 299118) Some burners used for heating with mazout, which atomize the fuel by compression (that is to say mostly those which are at present employed in large installations and in the marine art) cannot be adjusted. Their output is constant and to alter the amount of heating requires periodical extinction of some of the burners which constitute the heating group. For example, there is obtained a reduction of heating of 20% if one burner out of five is extinguished. This is not a great disadvantage where all the burners heat the same. hearth; when the burners each heat an individual hearth, it is not possible to adjust the general heating except by successively changing the burners, that is to say by replacing them by others which carry firing heads of different dimensions. This requires the successive extinction of burners to be changed, manipulation of valve gear, replacement, relighting, etc., and entails a great loss of time. Even when the operation is carried out by a specialist trained and used to it (who may not take much longer than a minute per apparatus) a change of speed on an oil-fired ship with twelve burners is an operation which takes a relatively long time.

The reasons which have made it impossible hitherto to adjust these known burners reside in the construction of their firing heads. These firing heads, which are very simple, comprise forward of the nozzle opening (these words forward of being considered as on the path of the fuel before the latter has reached the nozzle opening) a small circular chamber which is fed by one or more small inlet pipes, these latter being arranged in such a manner that the liquid fuel entering (either tangentially or at any other suitable angle) arrives in this, chamber in a state of turbulence arising from the effect of the feed pressure; this turbulence causes the jet, passing out through the nozzle (which is situated in the middle of the said chamber), to be rotated in such a manner that the liquid which is expelled is under the influence of two forces: one due to the pressure thrusts it forward axially of the nozzle, whilst the other due to the rotation causes dispersion by centrifugal force. I

Thus it is impossible to adjust the flow of fuel by altering the pressure of the fuel pumps because the result of a reduction of pressure would be a slowing down of the fuel in the inlet pipe or pipes which feed the. turbulence chamber and causev the turbulence, and thus would impair the atomisation.

If it were attempted to construct a firing head. with variable nozzle opening, the solution would be similarly ineffective because it again would not be possible to use this variation of section of the burner nozzle in order to vary the output of the burner without prejudicing the atomisation. It is in fact evident that when the nozzle orifice is of reduced section, the output will beautomatically reduced also and as no more liquid can enter into the small turbulence chamber (which feeds the nozzle) then comes out of it, the inlet pipe or pipes through which the liquid is introduced into the chamber would only let through liquid at a lower speed, as a nited States Patent 2 result of which. there would be a reduction of the dispersive centrifugal force.

The object of the present invention is to. provide a construction of firing head the output of which is variable without prejudice to the atomisation, the fineness, of which remains constant.

According to the. invention, this is achieved by varying in proportion the section ofthe outlet nozzle orifice and the totalsection ofthe inlet pipe or pipes which introduce the fuel into the turbulence chamber, this, proportionate variation being carried out in. such a manner that at any point in the range of adjustment, the ratio between these two sections. is always within permissible limits. for obtaining a suitable degree of dispersion.

The ratio between these sections is basically the same as that of compression pulversi'zers. There is an optimum ratio which it is necessary to conserve, andv it is to be, noted that when the total orifice of the inlet pipe or pipes becomes greater than is necessary with respect to the outlet. nozzle orifice, the. speed of rotation. diminishes, whilst. when it becomes. smaller, this speed subsists but the pressure falls in the chamber leading to axial slowing of the emergent fuel.

The varying of the two sections in proportion permits to, maintain the relationship between. the linear speed projecting, the liquid forward. and the speed of rotation which causes the dispersion constant.

The operation of an apparatus thus constructed reproduces, at. each position of adjustment, the usual functioning of a mazout compression burner in. which, the. same modification of the sections would have been obtained by changing the components of the burner. In, effect, the changing of the washer-like nozzle elements, in a burner of known kind, is nothing more than the putting in position in the apparatus of a new turbulence chamber comprising two orifices of shaping different from that of the preceding. chamber, but of the same proportion as those of said preceding chamber.

At a predetermined pressure it is not possible whilst conserving good operation, to vary the section of' only one orifice of the two; in effect, the enlargingof the nozzle orifice or the lessening of the total orifice of the inlet pipe or pipes will not slow down the rotation but will cause the pressure in the chamber to. drop, as a result of which there is a diminuation or elimination of the axial pressure. As a result, the apparatus drips or spits to the side; the contrary operation, consisting in the reduction of the, nozzle orifice or the enlarging of the total orifice of the inlet pipe or pipes would increase the pressure in the chamber but would cause there a diminution of the speed of turbulence, as a result of which there would be a lessening of the, dispersive force and thus projection forwardly of a jet which was only slightly dispersed, or not dispersed at all- An embodiment of burner in accordance with the in,- vention is hereinafter particularly described with reference to the accompanying drawing, wherein: Fig. 1 is a longitudinal central vertical section of the head of a burner; Figs. 2 to 6 show in separated position some of the members constituting the burner, Fig. 2. showing a cap, Fig. 3 showing, a socket, Fig. 4 showing an outlet nozzle, Fig. 5 showing a turbulence chamber, and Fig. 6 showing a valve member and threaded stem therefor; Figs. 7 and 8 are respectively an elevation and a central vertical section of a threaded boss receiving the valve member; Fig. 9 shows part of a guide socket at the end of a control rod for the valve; Fig. 10 is an elevation of part of a drive. member, and completes the element shown in Fig. 6'; Fig. 11. shows the forked end of the valve control' rod, to engage with the element of Fig. 10; Figs. 12 and 13 are respectively a front elevation and a perspective view of the turbulence chamber shown also in Fig. 5.

within the socket 2. Between the front face 7 of the turbulence chamber and the cap 15 is disposed a washerlike member 13 (see Fig. 4) having in it a bore 14 consisting of a frusto-conical part tapering to a cylindrical part, considered in the direction of flow of the fuel as explained hereinafter. The cap serves to clamp the members 13, 5 and 3 tightly together Within the socket 2. The turbulence chamber 5has a cylindrical axial bore 6 and also a number of radial channels 8 which lead into said bore from the space remaining outside the turbulence chamber 5 as the latter lies within the bore of the socket 2.

In the cylindrical bore of the turbulence chamber is disposed, in longitudinally slidable manner, a cylindrical valve member 9 formed integrally at the end of a threaded stem 10 carried at the end of a short shaft 11 terminating at its other end in a drive key member 20. The threaded stem 10 is rotatably engaged in the internal threading of the boss 3 so that rotation of the

assembly

9, 10, 11 and 19 causes axial movement of the valve member 9 with respect to the turbulence chamber 5 within which it is disposed. A rotatable axial control rod 16, connected to any suitable operating handle (not shown) to the right of Fig. 1, has at its end a guide socket 20 and in said socket a pair of fork arms 17 adapted to engage with the drive key member 20. It will be apparent that as the rod 16 is rotated, the valve member 9 will be shifted axially towards or away from the washer-like outlet nozzle member 13 according to the direction of rotation.

On the end of the valve member 9 adjacent to the washer-like member 13 there is disposed a cylindrical closure element 12 the diameter of which corresponds to the diameter of the cylindrical portion of the washer member 13, its length being such that when the main cylindrical body of the valve member 9 has advanced so far to the left (in Fig. 1) as to shut off the radial inlet passages 8 of the turbulence chamber 5, the lefthand end of closure element 12 has traversed the length of the frusto-conical portion of the bore of the member 13 and has thus closed the bore thereof against passage of fuel. Similarly, for all positions of adjustment of the valve member 9 to the left (in Fig. 1) to uncover the inlet passages 8 to any degree, the closure element 12 is withdrawn into the frusto-conical part of the bore of the washer-like member 13 to a corresponding extent.

In use, liquid fuel is forced under appropriate high pressure through the interior of the casing 18 towards the left-hand end (in Fig. 1) and passes through the gaps between the flanges 4 to the interior of the socket 2 and about the outside of the turbulence chamber 5. According to the degree of opening of the valve member 9 (i. e.

its extent of movement towards the right in Fig. 1) the inlet passages 8 will be open to a greater or lesser extent and will allow the fuel under pressure to enter tangentially into the bore of the turbulence chamber from whence it flows past the closure element 12 through the frusto-conical and cylindrical portions of the bore of the washer-like member 13, being thereafter discharged into the open through the wide opening of the cap 15.

Due to the entry of the liquid fuel into the chamber 5 tangentially and at a high speed because of its pressure, the fuel upon entering assumes a circular motion and, due to the continued supply, is also forced continuously out through the member 13. Thus the stream of fuel emerges with an axial movement (due to the feed pressure) and also a rotary movement (due to the action of the chamber 5). This rotary movement gives rise to a high degree of centrifugal force which causes the fuel stream to disperse in an approximately conical manner immediately upon emerging from the burner.

It will be clear that the operation of the burner, and the correct degree of dispersion, are dependent upon the speed with which the fuel can enter and leave the turbulence chamber 5. By the arrangement of the valve member 9, with its closure element 12, acting to close and open both the inlet and the outlet passages of the atomisation chamber in proportion, it is made possible to have a variable rate of flow of fuel without altering the fineness of dispersion of the fuel as it emerges.

I claim:

1. In a burner for liquid fuel, a hollow head having an inlet and an outlet passage for fuel, a cylindro-conical turbulence chamber in the head, said chamber having a cylindrical portion of greater diameter into which open tangential channels for the entry into the chamber of fuel coming from the interior of the head, said portion of greater diameter communicating through a conical portion with a cylindrical outlet passage of smaller diameter, a valve having two cylindrical portions of different diameter arranged in the chamber, the cylindrical portion of the valve of greater diameter being at the same end and of the same length as the part of the cylindrical chamber into which the tangential passages open, said valve being slidable in the chamber to permit the simultaneous variation, with a constant ratio preserved between them, of the flow into said chamber from the tangential passages controlled by the portion of the valve of greater diameter, and the flow out of the chamber through the annular gap defined between the end of the valve portion of smaller diameter and the commencement of the cylindrical outlet passage of the head.

2. In a burner for liquid fuel a hollow head having inlet and outlet opening means for liquid fuel, an outlet nozzle member in said head having a part cylindrical and part frusto-conical bore, the cylindrical portion being arranged after the frusto-conical portion in the direction of flow of the fuel and the frusto-conical portion tapering in the direction of How to the diameter of the cylindrical portion, an atomisation chamber member secured in the head and having a cylindrical bore of greater diameter than the frusto-conical bore and communicating therewith, said chamber member having inlet passage means for entry of fuel from the interior of the head tangentially into its cylindrical bore, and a cylindrical valve member slidably and rotatably arranged in the chamber member and having a coaxial screw-threaded stem threaded in the head, the valve member having two cylindrical portions of different chamber and of which the smaller diameter corresponds to the diameter of the cylindrical portion of the bore of the outlet nozzle and the greater diameter corresponds to the diameter of the cylindrical bore of the atomisation chamber, said valve member being arranged to coact with the said cylindrical bore of the outlet nozzle and with the tangential inlet passage means of the chamber member such that axial movement of the valve member serves to vary the cross-section of the nozzle bore and tangential inlet passage means of the chamber member simultaneously and in proportion.

References Cited in the file of this patent UNITED STATES PATENTS 1,102,352 Peabody et al July 5, 1914 1,725,381 Thomas Aug. 20, 1929 FOREIGN PATENTS 35,375 Norway July 24, 1922