U.S. patent number 3,753,642 [Application Number 05/248,075] was granted by the patent office on 1973-08-21 for high-capacity liquified fuel gas burner.
This patent grant is currently assigned to Shell Oil Company. Invention is credited to Guy Lamoureux.
United States Patent |
3,753,642 |
Lamoureux |
August 21, 1973 |
HIGH-CAPACITY LIQUIFIED FUEL GAS BURNER
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.
Inventors: |
Lamoureux; Guy (Grand-Couronne,
FR) |
Assignee: |
Shell Oil Company (New York,
NY)
|
Family
ID: |
22937568 |
Appl.
No.: |
05/248,075 |
Filed: |
April 27, 1972 |
Current U.S.
Class: |
431/89; 239/563;
239/570 |
Current CPC
Class: |
F23D
11/26 (20130101) |
Current International
Class: |
F23D
11/26 (20060101); F23D 11/24 (20060101);
F23n () |
Field of
Search: |
;431/89 ;239/563,570
;137/630.14 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dority, Jr.; Carroll B.
Claims
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 shut-off 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.
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.
Description
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 15 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 acting against 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.
A control rod 70 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 50a 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 70b 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 cap-shaped 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 displaced 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.sub.1 (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 92a 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.sub.2, 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
continue against the action of the two springs 80 and 94, until the
pressure reaches a maximum of p.sub.3 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 selection 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.
* * * * *