US3753642A

US3753642A - High-capacity liquified fuel gas burner

Info

Publication number: US3753642A
Application number: US00248075A
Authority: US
Inventors: G Lamoureux
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1972-04-27
Filing date: 1972-04-27
Publication date: 1973-08-21
Anticipated expiration: 1990-08-21

Abstract

A liquid fuel burner for LPG, the nozzle of which comprises at least two concentric series of orifices which are opened in succession by withdrawing a corresponding series of obturating valves connected with pressure sensitive controlling means (e.g., a membrane). The opening of the various series of valves is automatically controlled by the pressure of the liquid fuel supplied to the nozzle. By providing for more than one series of discharge openings the ratio of max. to min. discharge rates is very high, thus enabling ignition at a low discharge rate.

Description

United States Patent [191 Lamoureux Aug. 21, 1973 HIGH-CAPACITY LIQUIFIED FUEL GAS BURNER [75] Inventor: Guy Lamoureux, Grand-Couronne,

France [73] Assignee: Shell Oil Company, New York, N.Y.

[22] Filed: Apr. 27, 1972 [21] Appl. No.: 248,075

[52] 11.5. C1 431/89, 239/563, 239/570 [51] Int. Cl. F23n [58] Field of Search 431/89; 239/563,

[56] References Cited UNITED STATES PATENTS 3,3 1 5,726 4/1967 Williams 431/89 Primary Examiner-Carroll B. Dority, Jr. Attorney-Harold L. Denkler et al.

[5 7 ABSTRACT A liquid fuel burner for LPG, the nozzle of which comprises at least two concentric series of orifices which are opened in succession by withdrawing a corresponding series of obturating valves connected with pressure sensitive controlling means (e.g., a membrane). The opening of the various series of valves is automatically controlled by the pressure of the liquid fuel supplied to the nozzle. By providing for more than one series of discharge openings the ratio of max. to min. discharge rates is very high, thus enabling ignition at a low discharge rate.

9 Claims, 2 Drawing Figures Patented Aug. 21, 1973 mm mm N0 Nv q mv Qv mm a 3 8 mm mm HIGH-CAPACITY LIQUIFIED FUEL GAS BURNER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fuel gas burners, for example butane or propane burners of a type in which the fuel is introduced into the burner in the liquid state for discharge by means of an atomizer. Such a burner will be defined hereinafter as a burner of the type specified.

Burners of this type may be used as high-capacity heaters, for example with a capacity of more than 60th/h.

2. Description of the Prior Art It is generally desirable for burners of the type specified to have a very wide range of load limits so as to impart to the burner a high operating flexibility. Especially to enable the burners to be ignited by an electric device, it is desirable that the fuel consumption rate or load of the burner at the moment of ignition is substantially lower than its nominal load, for example at most equal to percent of this nominal load.

Further, it is preferred that the post-ignition load should permit of being increased smoothly and in regular progression.

Taking into account the vapor pressure of the liquified fuel gases of the above-mentioned type and the characteristics of currently available pumps, the burner feed pressure generally must vary between approximately 2.5 and 10 bars. Consequently, if only the variations in pressure are used it is impossible to obtain a load which varies regularly between wide limits; in fact the atomizer load necessarily varies with the square root of the pressure. Since the latter, as stated above, varies in a range of from 1 to 4 times the minimum pressure, the load can only vary from 1 to 2 times the minimum load.

SUMMARY OF THE INVENTION An object of the invention is to provide means for obtaining widely varying load limits in burners of the above-mentioned type, the load increase preferably being effected in proportion to the rise in pressure.

To this end the present invention particularly refers to a burner of the type specified, wherein valved atomizing orifices are put into operation, in dependency on the internal pressure, and under predetermined conditions of pressure and feed control.

According to the invention a burner of the type specified is characterized in that the atomizer is provided with at least two series of orifices for the passage of fluid, each series of orifices co-operating with a shut-off valve, and that the valves are opened one by one by the displacement of a single control element actuated by the internal pressure of the burner.

According to one feature of the invention, the control element actuated by the internal pressure of the burner is a control rod connected to a membrane which is sensitive to the internal pressure.

According to another feature of the invention, the said control rod is located in the central axis of symmetry of the burner, the series of orifices are arranged concentrically in rings around this axis and the shut-off valves are telescopically mounted relative to each other and in alignment with the said axis. The valve closing the ring of orifices with the smallest diameter preferably forms part of the control rod.

According to still another feature of the invention, the membrane is provided with an adjustable spring actingagainst the internal pressure in the burner.

The burner preferably comprises three chambers separated by two partitions which serve as guides for the control rod and are provided with orifices by which the chambers are in communication with each other. The central chamber which has a small volume, receives the fluid under pressure; the front chamber, one wall of which is formed by the atomizer, accommodates the valves; the rear chamber, which has a large volume, accommodates the regulating membrane.

BRIEF DESCRIPTION OF THE DRAWINGS Further features and advantages of the invention will become apparent from the following description and from the attached drawings, in which:

FIG. 1 is an axial cross-section of a burner according to the invention;

FIG. 2 is a diagram showing the variations in the burner load as a function of variations in the internal supply pressure.

DESCRIPTION OF A PREFERRED EMBODIMENT The .burner of FIG. 1 is arranged symmetrically round a central axis AA. It comprises an outer body 10 consisting of a tublar front part 11, a cylindrical rear part 12 having a large diameter relative to the front part 11, and a flared part 13 connecting the

parts

11 and 12.

The burner is supplied with fuel through a nozzle 20, which is connected to the body of the burner at the rear end of part 11.

The interior of the body 10 is subdivided into three

chambers

30, 31, and 32 by two

partitions

14 and 15, each of which is provided with a central opening (14a, 15a) and orifices for the passage of fluid (14b, 15b).

The front chamber 30 is confined at the front end by an atomizing system consisting of a plate 40 mounted to the end of the part 11 by means of a cap nut 41. The atomizer is provided with two rings of

orifices

42 and 43, which are arranged in different diameters round the axis AA.

The nozzle 20 debouches into the central chamber 31, the

orifices

14b and 15b for the passage of fluid permitting the fuel supplied via the nozzle 20 to pass from the chamber 31 to the other two

chambers

30 and 32.

The rear chamber 32 is confined at the back by a membrane 50 which is mounted to an internal annular shoulder 13a of the part 13. A tight fit of the outer circumference of the membrane 50 against the shoulder 13a by means of a gasket 51 is ensured by a rim 61 of a cover 60 screwed into the inside of the part 12. The bottom 62 of the cover 60 is provided with orifices 62a by which the interior 63 of the cover behind the membrane 50 communicates with the outside atmosphere.

At its center the bottom 62 is provided with a threaded opening 64 accommodating a stop screw 65, which can be adjusted and locked by means of a locking nut 66. The front part of the screw 65 has an axial cylindrical recess 67. I

A control rod is connected to the membrane 50 in a manner known per se, which rod has a front part 70a of large diameter and a threaded rear part 70b of smaller diameter. The membrane is slid with its central opening 500 over the part 70b of the rod and a nut 71 cooperating with the part 70b ensures, by means of a gasket 72, that the rim of the opening 50a of the membrane 50 is clamped against the shoulder 73 which separates the parts 70a and 70b of the rod.

The end of the part 7012 mates with the cylindrical recess 67 in which it can slide freely, the bottom of the recess 67 acting as stop for the end of 70b. A compression spring 80 is provided round 70b; one end of this spring 80 abuts on the nut 71, the other end on the front end 65a of the screw 65.

The front part 70a of the control rod 70 can slide in the

central openings

14a and 15a which serve as bearings for the rod.

The series of orifices 42 can be closed by a valve 92 which is mounted to the end of a rod 92a screwed into the front part of 70a.

The series of orifices 43 can be closed by a capshaped valve 93, which surrounds the valve 92 and is slideably mounted to the threadless front part of the rod 92a. The orifices 93a run through the valve 93 in order that this valve will never interrupt the fuel supply to the orifices 42.

The valve 93 is forced to its closed position against the orifices 43 by a spring 94, which is slid on the rod 92a and abuts on a nut 95 which is provided on the threaded rear part of the rod 92a and is secured by a locking nut 96.

Finally, the valve 92 serving to close the first series of orifices 42 forms part of the rod 70 which is dis placed in response to the deformation of the membrane against the action of the spring 80, the compression of which can be adjusted by means of the screw 65. On the other hand, the valve 93 is slideably mounted to the rod 92a and continuously forced to its closed position by the spring 94, the compression of which can be adjusted by means of the nut 95. Finally, backward movement of the rod 92a causes the valve 92 to come into contact with the bottom of the cap valve 93. The

openings

14b and 15b of

partitions

14 and 15 and the openings 93a provided in the valve 93 establish communication between the various zones of the

chambers

30, 31 and 32.

Under these conditions the operation of the system is easy to understand. From the following description it will be clear what happens upon a rise in the supply pressure of the fuel entering the burner through the nozzle 20.

In the initial position, which is shown in FIG. 1, the two

valves

92 and 93 are in closed position, valve 92 being subject to the action of the spring 80 which forces the rod 70 forward and valve 93 being subject to the action of the spring 94. When the liquified fuel is introduced into the burner through the nozzle 20, the pressure rises simultaneously in the three

chambers

30, 31 and 32. At a pressure p, (see also FIG. 2), the membrane 50 is forced rearwardly against the action of the spring 80 while moving the rod 70 which forms part of the rod 920 of the valve 92. The latter moves away from the orifices 42 which are thus uncovered. The fuel is discharged through these orifices. When the pressure continues to build up, the load keeps going up with the square root of the pressure. The membrane 50 and the rod 70 continue their travel to the rear end of the burner. At a pressure p the displacement reaches the point where the valve 92 contacts the valve 93. When this movement persists, the valve 92 forces the valve 93 backwards, leaving the orifices 43 uncovered. From this moment the load increases abruptly, since the fuel is being discharged through the two series of

orifices

42 and 43. The rise in pressure and the displacement to the rear end of the

assembly

70, 92 and 93 may con- 5 tinue against the action of the two

springs

80 and 94, until the pressure reaches a maximum of p;, or until the rear end face of 70b contacts the bottom of the recess 67.

FIG. 2 shows the curve of the variation in load as a function of the supply pressure. The actual variation is shown by means of a solid line and is affected by the characteristics of the springs, the valves and the orifices co-operating with the valves, and the various control effects which become particularly manifest between the orifices and their valve. The theoretical curve is given by means of a broken line and is based on the assumption that the valves open freely, without being subject to any control effect.

The theoretical curve shows a sudden rise when the valve 93 opens. On the other hand, the actual curve shows a regular progression owing to a judicious selec tion of the various components mentioned above, especially those on which the control effect depends. This represents an important characteristic feature of the invention.

it will be apparent that the invention is not limited to the embodiments herein described but is extended to include any alternatives within the scope of the invention. in particular, it is possible to use more than two valves which are telescopically arranged relative to each other, one valve being capable of moving the next one.

I claim as my invention:

1. In a burner for liquid fuel of the type comprising a housing having at least one hollow fuel supply chamber therein; means for admitting liquid fuel into the chamber; and atomizer means comprising a plurality of orifices for discharging atomized fuel from the fuel supply chamber into a zone of combustion, the improvement comprising:

at least two series of orifices provided in the atomizer means, each series comprising at least one orifice;

at a plurality of shut-off valve means, at least one shut-off valve means for each series of orifices, positioned in the housing to control flow through the atomizer; and

control means for opening and closing said shut-off valve means independently in response to changes in fluid pressure in said fuel supply chamber.

2. The burner of claim 1 wherein the control means comprises:

a flexible membrane positioned in the housing to form at least a portion of a wall of said fuel supply chamber, in operation, said membrane being displaced inwardly and outwardly with respect to the fuel supply chamber in response to fluid pressure change within the fuel supply chamber; and

a connecting rod for opening and closing said shutoff valve means in response to displacement of said flexible membrane operatively connecting said flexible membrane to said shut-off valve means.

3. The burner of claim 2 wherein said control means further comprises a spring position in the housing and operatively associated with said flexible membrane to bias said flexible membrane toward an inwardly flexed position with respect to the fuel supply chamber.

4. The burner of claim 3 wherein said connecting rod has a longitudinal axis and is slideably positioned in the housing for axial movement with respect to that longitudinal axis; and wherein at least a first of said shut-off valve means is fixedly connected to said connecting rod.

5. The burner of claim 4 wherein a second of said shut-off valve means is slideably connected to said connecting rod and further including:

means for limiting sliding motion of said connecting rod with respect to said second shut-off valve means to a selected limited distance; and

means for exerting a closing force on said second valve means to bias said second shut-off valve means to a closed position,

whereby said connecting rod is free to move a selected limited distance in response to outward displacement of said membrane without moving said second shut-off valve means from said closed position and whereby further movement of said connecting rod in response to outward displacement of said membrane causes said connecting rod to exert an opening force on said second shut-off valve means in opposition to said biasing means which opening force is proportional to the force exerted on the flexible membrane by fluid pressure within the chamber, said second shut-off valve means opening when the opening force exceeds the force exerted by the biasing means. i

6. The burner of claim 5 wherein the burner has a central axis of symmetry;

wherein each series of orifices comprises a plurality of orifices positioned equidistant from the central axis of symmetry so as to define a circular ring of orifices, each series of orifices defining a circular ring of different diameter, the circular rings of different diameter defined by the series of orifices being concentric;

wherein the longitudinal axis of the connecting rod is co-linear with the central axis of symmetry; and

wherein the shut-off valves are telescopically connected to the connecting rod, the first and second shut-off valve means controlling fuel flow through orifices in different rings of said concentric rings of orifices, the first shut-off valve means controlling fluid flow through orifices in a ring of orifices of diameter less than the diameter of the ring of orifices in which the second shut-off valve means controls fuel flow.

7. The burner of claim 6 wherein said means for exerting a force to the second shut-off valve means to a normally closed position is adjustable.

8. The burner of claim 2 wherein the fuel supply chamber is subdivided into three chamber portions by two perforate partitions disposed in the housing; and wherein said partitions slideably support said connecting rod within the housing.

9. The burner of claim 8 wherein the fuel supply chamber comprises:

a cylindrical front chamber between said atomizer means and a first of the two partitions;

a second cylindrical chamber between the two partitions, said means for admitting liquid fuel into the fuel supply chamber being operatiavely connected to said second cylindrical chamber; and

a flared rear chamber between the second of said two partitions and an end wall of said fuel supply chamber opposite said atomizer means, at least a portion of said end wall being formed by said flexible membrane.

Claims

1. In a burner for liquid fuel of the type comprising a housing having at least one hollow fuel supply chamber therein; means for admitting liquid fuel into the chamber; and atomizer means comprising a plurality of orifices for discharging atomized fuel from the fuel supply chamber into a zone of combustion, the improvement comprising: at least two series of orifices provided in the atomizer means, each series comprising at least one orifice; at a plurality of shut-off valve means, at least one shut-off valve means for each series of orifices, positioned in the housing to control flow through the atomizer; and control means for opening and closing said shut-off valve means independently in response to changes in fluid pressure in said fuel supply chamber.

2. The burner of claim 1 wherein the control means comprises: a flexible membrane positioned in the housing to form at least a portion of a wall of said fuel supply chamber, in operation, said membrane being displaced inwardly and outwardly with respect to the fuel supply chamber in response to fluid pressure change within the fuel supply chamber; and a connecting rod for opening and closing said shut-off valve means in response to displacement of said flexible membrane operatively connecting said flexible membrane to said shut-off valve means.

5. The burner of claim 4 wherein a second of said shut-off valve means is slideably connected to said connecting rod and further including: means for limiting sliding motion of said connecting rod with respect to said second shut-off valve means to a selected limited distance; and means for exerting a closing force on said second valve means to bias said second shut-off valve means to a closed position, whereby said connecting rod is free to move a selected limited distance in response to outward displacement of said membrane without moving said second shut-off valve means from said closed position and whereby further movement of said connecting rod in response to outward displacement of said membrane causes said connecting rod to exert an opening force on said second shut-off valve means in opposition to said biasing means which opening force is proportional to the force exerted on the flexible membrane by fluid pressure within the chamber, said second shut-off valve means opening when the opening force exceeds the force exerted by the biasing means.

6. The burner of claim 5 wherein the burner has a central axis of symmetry; wherein each series of orifices comprises a plurality of orifices positioned equidistant from the central axis of symmetry so as to define a circular ring of orifices, each series of orifices defining a circular ring of different diameter, the circular rings of different diameter defined by the series of orifices being concentric; wherein the longitudinal axis of the connecting rod is co-linear with the central axis of symmetry; and wherein the shut-off valves are telescopically connected to the connecting rod, the first and second shut-off valve means controlling fuel flow through orifices in different rings of said concentric rings of orifices, the first shut-off valve means controlling fluid flow through orifices in a ring of orifices of diameter less than the diameter of the ring of orifices in which the second shut-off valve means controls fuel flow.

9. The burner of claim 8 wherein the fuel supply chamber comprises: a cylindrical front chamber between said atomizer means and a first of the two partitions; a second cylindrical chamber between the two partitions, said means for admitting liquid fuel into the fuel supply chamber being operatiavely connected to said second cylindrical chamber; and a flared rear chamber between the second of said two partitions and an end wall of said fuel supply chamber opposite said atomizer means, at least a portion of said end wall being formed by said flexible membrane.