U.S. patent application number 12/373562 was filed with the patent office on 2009-12-10 for two-fluid spray burner.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Akira Goto, Naohiko Matsuda, Keiichi Nakagawa, Shigeru Nojima, Katsuki Yagi.
Application Number | 20090305178 12/373562 |
Document ID | / |
Family ID | 39032960 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090305178 |
Kind Code |
A1 |
Nakagawa; Keiichi ; et
al. |
December 10, 2009 |
TWO-FLUID SPRAY BURNER
Abstract
An object of the present invention is to provide a two-fluid
spray burner in which liquid fuel can be stably supplied without
causing large fluctuation in flow rate of supplied liquid fuel even
when the flow rate of supplied liquid fuel is low. In a two-fluid
spray burner (11) which atomizes liquid fuel (24) with atomizing
air and burns the same, the burner includes: a liquid fuel tank
(19) including a cylindrical side portion (20) and a bottom portion
(21) provided at a lower end of the side portion (20), the liquid
fuel tank (19) storing liquid fuel (24) supplied from a liquid fuel
supply tube (25) and discharging the stored liquid fuel (24) from a
liquid fuel discharge hole (22) opened in the bottom portion (21)
below a liquid level (23) of the stored liquid fuel (24). The
liquid fuel (24) discharged from the liquid fuel discharge hole
(22) of the liquid fuel tank (19) is atomized with atomizing gas
(46) and is burned.
Inventors: |
Nakagawa; Keiichi;
(Hiroshima-shi, JP) ; Matsuda; Naohiko;
(Hiroshima-shi, JP) ; Nojima; Shigeru;
(Hiroshima-shi, JP) ; Yagi; Katsuki;
(Hiroshima-shi, JP) ; Goto; Akira; (Yokohama-shi,
JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
Tokyo
JP
NIPPON OIL CORPORATION
Tokyo
JP
|
Family ID: |
39032960 |
Appl. No.: |
12/373562 |
Filed: |
August 7, 2007 |
PCT Filed: |
August 7, 2007 |
PCT NO: |
PCT/JP2007/065401 |
371 Date: |
April 2, 2009 |
Current U.S.
Class: |
431/159 |
Current CPC
Class: |
F23D 11/404 20130101;
F23D 11/107 20130101 |
Class at
Publication: |
431/159 |
International
Class: |
F23D 11/00 20060101
F23D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 11, 2006 |
JP |
2006-219574 |
Claims
1. A two-fluid spray burner which atomizes liquid fuel with
atomizing gas and burns the atomized liquid fuel, the burner
comprising: a liquid fuel tank including: a cylindrical side
portion and a bottom portion provided at a lower end of the side
portion, the liquid fuel tank storing liquid fuel supplied from a
liquid fuel supply tube and discharging the stored liquid fuel from
one or a plurality of liquid fuel discharge holes opened in the
side or bottom portion at a position below a liquid level of the
stored liquid fuel, the burner characterized in that the liquid
fuel discharged from the liquid fuel discharge hole of the liquid
fuel tank is atomized with the atomizing gas and burned.
2. The two-fluid spray burner according to claim 1, characterized
in that the liquid fuel discharge holes are opened in the bottom
portion of the liquid fuel tank, the burner further comprising: a
cylindrical atomizing gas passage formed between the side portion
of the liquid fuel tank and an outer cylinder surrounding a
periphery of the side portion; and a two-fluid spray nozzle
provided at a lower end portion of the outer cylinder and including
a lower nozzle main body and an upper atomizing gas introduction
portion, the two-fluid spray nozzle having: a two-fluid converging
space portion formed under the liquid fuel discharge holes, in
central part of the nozzle main body and the atomizing gas
introduction portion; one or a plurality of spray holes formed in
the nozzle main body and leading to the two-fluid converging space
portion; and one or a plurality of grooves formed in the atomizing
gas introduction portion and allowing the two-fluid converging
space portion and the atomizing gas passage to communicate with
each other, the burner characterized in that the liquid fuel tank
is installed on the atomizing gas introduction portion, and the
liquid fuel which is discharged from the liquid fuel discharge
holes to flow into the two-fluid converging space portion converges
at the two-fluid converging space portion with the atomizing gas
which flows down the atomizing gas passage and flows through the
grooves at the atomizing gas introduction portion to be introduced
to the two-fluid converging space portion, and the liquid fuel is
then sprayed together with the atomizing gas from the spray
holes.
3. The two-fluid spray burner according to claim 2, further
comprising an undersurface of the bottom portion of the liquid fuel
tank formed as a tapered surface portion which is tapered, a top
surface of the atomizing gas introduction portion also formed as a
tapered surface portion which is tapered, and the liquid fuel tank
installed on the atomizing gas introduction portion with the
tapered surface portion of the liquid fuel tank abutted and fitted
to the tapered surface portion of the atomizing gas introduction
portion.
4. The two-fluid spray burner according to claim 1, characterized
in that the liquid fuel discharge holes are opened in the bottom
portion of the liquid fuel tank, the burner further comprising: a
cylindrical atomizing gas passage formed between the side portion
of the liquid fuel tank and an outer cylinder surrounding a
periphery of the side portion; and a two-fluid spray nozzle
provided at a lower end portion of the outer cylinder, the
two-fluid spray nozzle having: a two-fluid converging space portion
formed in central part under the liquid fuel discharge holes, and
one or a plurality of spray holes formed, leading to the two-fluid
converging space portion, the burner characterized in that the
undersurface of the bottom portion of the liquid fuel tank is
formed as a tapered surface portion which is tapered, the top
surface of the two-fluid spray nozzle is also formed as a tapered
surface portion which is tapered, the liquid fuel tank is installed
on the two-fluid spray nozzle with the tapered surface portion of
the liquid fuel tank abutted and fitted to the tapered surface
portion of the two-fluid spray nozzle, one or a plurality of
grooves are formed at the bottom portion of the liquid fuel tank,
the grooves allowing the atomizing gas passage and the two-fluid
converging space portion to communicate with each other, and the
liquid fuel discharged from the liquid fuel discharge holes to flow
into the two-fluid converging space portion converges at the
two-fluid converging space portion with the atomizing gas which
flows down the atomizing gas passage and then flows through the
grooves at the bottom portion of the liquid fuel tank to be
introduced to the two-fluid converging space portion, and the
liquid fuel is then sprayed together with the atomizing gas from
the spray holes.
5. The two-fluid spray burner according to claim 2, wherein the
two-fluid converging space portion has a circular shape in a top
view, and the grooves of the atomizing gas introduction portion or
the grooves of the bottom portion of the liquid fuel tank are
formed along tangent directions of a circumference of the two-fluid
converging space portion in the top view.
6. The two-fluid spray burner according to claim 2, wherein the
two-fluid converging space portion has a circular shape in a top
view, and the grooves of the atomizing gas introduction portion or
the grooves of the bottom portion of the liquid fuel tank are
formed along radial directions of the two-fluid converging space
portion in the top view.
7. The two-fluid spray burner according to claim 5, wherein the
plurality of grooves of the atomizing gas introduction portion or
the plurality of grooves of the bottom portion of the liquid fuel
tank are formed at positions rotationally symmetric around a
central axis of the two-fluid converging space portion.
8. The two-fluid spray burner according to claim 2, further
comprising: a press member pressing the liquid fuel tank downward,
characterized in that the bottom portion of the liquid fuel tank is
pressed against the atomizing air introduction portion of the
two-fluid spray nozzle to be brought into firm contact or the
bottom portion of the liquid fuel tank is pressed against the
two-fluid spray nozzle to be brought into firm contact.
9. The two-fluid spray burner according to claim 1, wherein the
liquid fuel discharge holes are opened in the bottom portion of the
liquid fuel tank, the burner characterized by further comprising: a
cylindrical first atomizing gas passage formed between the side
portion of the liquid fuel tank and an outer cylinder surrounding a
periphery of the side portion; and a two-fluid spray nozzle
provided at a lower end portion of the outer cylinder, the
two-fluid spray nozzle having: a two-fluid converging space portion
formed in center part under the liquid fuel discharge holes and one
or a plurality of spray holes formed, leading to the two-fluid
converging space portion, the burner characterized in that the top
surface of the two-fluid spray nozzle is formed as a tapered
surface portion which is tapered, the undersurface of the bottom
portion of the liquid fuel tank is formed as a tapered surface
portion which is tapered, a plurality of supporting portions
protrude on the side portion of the liquid fuel tank, and each
undersurface of the supporting portions is formed as a tapered
surface portion, the liquid fuel tank is installed on the two-fluid
spray nozzle with the tapered surface portions of the supporting
portions being abutted and fitted to the tapered surface portion of
the two-fluid spray nozzle, gap formed by the supporting portions
between the tapered surface portion of the liquid fuel tank and the
tapered surface portion of the two-fluid spray nozzle is a second
atomizing gas passage, and the liquid fuel discharged from the
liquid fuel discharge holes to flow into the two-fluid converging
space portion converges at the two-fluid converging space with the
atomizing gas which flows down the first atomizing gas passage,
passes through atomizing gas passage portions between the
supporting portions, and flows through the second atomizing gas
passage to be introduced to the two-fluid converging space portion
and is then sprayed together with the atomizing gas from the spray
holes.
10. The two-fluid spray burner according to claim 2, wherein the
two-fluid converging space portion is a reverse conical shape, and
the spray holes are formed at a vertex position of the reverse
conical space.
11. The two-fluid spray burner according to claim 2, further
comprising a cylindrical gas fuel passage formed between the outer
cylinder and a gas fuel supply tube surrounding a periphery of the
outer cylinder, the burner characterized in that gas fuel flows
down the gas fuel passage and is sprayed from a lower end of the
gas fuel passage to be burned.
12. The two-fluid spray burner according to claim 1, wherein an end
of the liquid fuel supply tube is in contact with an inner
peripheral surface of the side portion of the liquid fuel tank.
13. The two-fluid spray burner according to claim 4, wherein the
two-fluid converging space portion has a circular shape in a top
view, and the grooves of the atomizing gas introduction portion or
the grooves of the bottom portion of the liquid fuel tank are
formed along tangent directions of a circumference of the two-fluid
converging space portion in the top view.
14. The two-fluid spray burner according to claim 4, wherein the
two-fluid converging space portion has a circular shape in a top
view, and the grooves of the atomizing gas introduction portion or
the grooves of the bottom portion of the liquid fuel tank are
formed along radial directions of the two-fluid converging space
portion in the top view.
15. The two-fluid spray burner according to claim 13, wherein the
plurality of grooves of the atomizing gas introduction portion or
the plurality of grooves of the bottom portion of the liquid fuel
tank are formed at positions rotationally symmetric around a
central axis of the two-fluid converging space portion.
16. The two-fluid spray burner according to claim 6, wherein the
plurality of grooves of the atomizing gas introduction portion or
the plurality of grooves of the bottom portion of the liquid fuel
tank are formed at positions rotationally symmetric around a
central axis of the two-fluid converging space portion.
17. The two-fluid spray burner according to claim 13, wherein the
plurality of grooves of the atomizing gas introduction portion or
the plurality of grooves of the bottom portion of the liquid fuel
tank are formed at positions rotationally symmetric around a
central axis of the two-fluid converging space portion.
18. The two-fluid spray burner according to claim 4, further
comprising: a press member pressing the liquid fuel tank downward,
characterized in that the bottom portion of the liquid fuel tank is
pressed against the atomizing air introduction portion of the
two-fluid spray nozzle to be brought into firm contact or the
bottom portion of the liquid fuel tank is pressed against the
two-fluid spray nozzle to be brought into firm contact.
19. The two-fluid spray burner according to claim 4, wherein the
two-fluid converging space portion is a reverse conical shape, and
the spray holes are formed at a vertex position of the reverse
conical space.
20. The two-fluid spray burner according to claim 9, wherein the
two-fluid converging space portion is a reverse conical shape, and
the spray holes are formed at a vertex position of the reverse
conical space.
21. The two-fluid spray burner according to claim 4, further
comprising a cylindrical gas fuel passage formed between the outer
cylinder and a gas fuel supply tube surrounding a periphery of the
outer cylinder, the burner characterized in that gas fuel flows
down the gas fuel passage and is sprayed from a lower end of the
gas fuel passage to be burned.
22. The two-fluid spray burner according to claim 9, further
comprising a cylindrical gas fuel passage formed between the outer
cylinder and a gas fuel supply tube surrounding a periphery of the
outer cylinder, the burner characterized in that gas fuel flows
down the gas fuel passage and is sprayed from a lower end of the
gas fuel passage to be burned.
Description
TECHNICAL FIELD
[0001] The present invention relates to a two-fluid spray burner
which burns liquid fuel atomized with atomizing gas.
BACKGROUND ART
[0002] A two-fluid spray burner burns liquid fuel atomized with
atomizing gas and is used as a heat source of a reformer of a fuel
power generation system or the like, for example.
[0003] In a conventional two-fluid spray burner, liquid fuel is
supplied from a pump of a liquid fuel supply system through a
liquid fuel supply tube and discharged from an end of the liquid
fuel supply tube. The liquid fuel discharged from the liquid fuel
supply tube is mixed with atomizing air, so that the liquid fuel is
atomized and burned.
[0004] Patent Document 1: Japanese Patent Laid-open No.
2002-224592
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0005] However, the above-described conventional two-fluid spray
burner is designed on assumption that the liquid fuel is supplied
from the pump at a high flow rate. Accordingly, when the
conventional two-fluid spray burner is used in a state where flow
of supplied liquid fuel is low, the liquid fuel is intermittently
(in a vibrating manner) supplied from the pump, and the liquid fuel
is therefore intermittently discharged from an end 1A of a liquid
fuel supply tube 1 as illustrated in FIG. 14(a). Accordingly, as
illustrated in FIG. 14(b), the flow rate of supplied liquid fuel
greatly fluctuates. This prevents stable supply of liquid fuel and
makes it difficult to achieve stable combustion, thus generating
unburned exhaust gas or causing accidental fire.
[0006] One of the countermeasures to this problem is to increase
pump performances of the liquid fuel supply system so that fuel is
stably supplied even at a low flow rate. However, such a
countermeasure requires an expensive pump and increases costs of
the apparatus.
[0007] Accordingly, in the light of the aforementioned
circumstances, an object of the present invention is to provide a
two-fluid spray burner capable of stably supplying liquid fuel
without causing large fluctuations in flow rate of supplied liquid
fuel even when the flow rate of supplied liquid fuel is low.
Means for Solving the Problems
[0008] A two-fluid spray burner of a first invention to solve the
aforementioned problems is a two-fluid spray burner which atomizes
liquid fuel with atomizing gas and burns the atomized liquid fuel,
characterized by comprising:
[0009] a liquid fuel tank including: a cylindrical side portion and
a bottom portion provided at a lower end of the side portion, the
liquid fuel tank storing liquid fuel supplied from a liquid fuel
supply tube and discharging the stored liquid fuel from one or a
plurality of liquid fuel discharge holes opened in the side or
bottom portion at a position below a liquid level of the stored
liquid fuel, the burner characterized in that
[0010] the liquid fuel discharged from the liquid fuel discharge
hole of the liquid fuel tank is atomized with the atomizing gas and
burned.
[0011] A two-fluid spray burner of a second invention is the
two-fluid spray burner of the first invention characterized in that
the liquid fuel discharge holes are opened in the bottom portion of
the liquid fuel tank,
[0012] the burner characterized by further comprising:
[0013] a cylindrical atomizing gas passage formed between the side
portion of the liquid fuel tank and an outer cylinder surrounding a
periphery of the side portion; and
[0014] a two-fluid spray nozzle provided at a lower end portion of
the outer cylinder and including a lower nozzle main body and an
upper atomizing gas introduction portion, the two-fluid spray
nozzle having: [0015] a two-fluid converging space portion formed
under the liquid fuel discharge holes, in central part of the
nozzle main body and the atomizing gas introduction portion; [0016]
one or a plurality of spray holes formed in the nozzle main body
and leading to the two-fluid converging space portion; and [0017]
one or a plurality of grooves formed in the atomizing gas
introduction portion and allowing the two-fluid converging space
portion and the atomizing gas passage to communicate with each
other,
[0018] the burner characterized in that
[0019] the liquid fuel tank is installed on the atomizing gas
introduction portion, and
[0020] the liquid fuel which is discharged from the liquid fuel
discharge holes to flow into the two-fluid converging space portion
converges at the two-fluid converging space portion with the
atomizing gas which flows down the atomizing gas passage and flows
through the grooves at the atomizing gas introduction portion to be
introduced to the two-fluid converging space portion, and the
liquid fuel is then sprayed together with the atomizing gas from
the spray holes.
[0021] A two-fluid spray burner according to a third invention is
the two-fluid spray burner of the second invention characterized in
that
[0022] an undersurface of the bottom portion of the liquid fuel
tank is formed as a tapered surface portion which is tapered,
[0023] a top surface of the atomizing gas introduction portion is
also formed as a tapered surface portion which is tapered, and
[0024] the liquid fuel tank is installed on the atomizing gas
introduction portion with the tapered surface portion of the liquid
fuel tank abutted and fitted to the tapered surface portion of the
atomizing gas introduction portion.
[0025] A two-fluid spray burner of a fourth invention is the
two-fluid spray burner of the first invention characterized in that
the liquid fuel discharge holes are opened in the bottom portion of
the liquid fuel tank, the burner characterized by further
comprising:
[0026] a cylindrical atomizing gas passage formed between the side
portion of the liquid fuel tank and an outer cylinder surrounding a
periphery of the side portion; and
[0027] a two-fluid spray nozzle provided at a lower end portion of
the outer cylinder, the two-fluid spray nozzle having: [0028] a
two-fluid converging space portion formed in central part under the
liquid fuel discharge holes, and [0029] one or a plurality of spray
holes formed, leading to the two-fluid converging space
portion,
[0030] the burner characterized in that
[0031] the undersurface of the bottom portion of the liquid fuel
tank is formed as a tapered surface portion which is tapered,
[0032] the top surface of the two-fluid spray nozzle is also formed
as a tapered surface portion which is tapered,
[0033] the liquid fuel tank is installed on the two-fluid spray
nozzle with the tapered surface portion of the liquid fuel tank
abutted and fitted to the tapered surface portion of the two-fluid
spray nozzle,
[0034] one or a plurality of grooves are formed at the bottom
portion of the liquid fuel tank, the grooves allowing the atomizing
gas passage and the two-fluid converging space portion to
communicate with each other, and
[0035] the liquid fuel discharged from the liquid fuel discharge
holes to flow into the two-fluid converging space portion converges
at the two-fluid converging space portion with the atomizing gas
which flows down the atomizing gas passage and then flows through
the grooves at the bottom portion of the liquid fuel tank to be
introduced to the two-fluid converging space portion, and the
liquid fuel is then sprayed together with the atomizing gas from
the spray holes.
[0036] A two-fluid spray burner of a fifth invention is the
two-fluid spray burner of any one of the second to fourth
inventions characterized in that
[0037] the two-fluid converging space portion has a circular shape
in a top view, and
[0038] the grooves of the atomizing gas introduction portion or the
grooves of the bottom portion of the liquid fuel tank are formed
along tangent directions of a circumference of the two-fluid
converging space portion in the top view.
[0039] A two-fluid spray burner of the sixth invention is the
two-fluid spray burner according to any one of the second to fourth
inventions, characterized in that the two-fluid converging space
portion has a circular shape in a top view, and
[0040] the grooves of the atomizing gas introduction portion or the
grooves of the bottom portion of the liquid fuel tank are formed
along radial directions of the two-fluid converging space portion
in the top view.
[0041] A two-fluid spray burner of a seventh invention is the
two-fluid spray burner of the fifth or sixth invention
characterized in that the plurality of grooves of the atomizing gas
introduction portion or the plurality of grooves of the bottom
portion of the liquid fuel tank are formed at positions
rotationally symmetric around a central axis of the two-fluid
converging space portion.
[0042] A two-fluid spray burner of an eighth invention is the
two-fluid spray burner of any one of the second to seventh
inventions, the burner characterized by further comprising:
[0043] a press member pressing the liquid fuel tank downward, in
which
[0044] the bottom portion of the liquid fuel tank is pressed
against the atomizing air introduction portion of the two-fluid
spray nozzle to be brought into firm contact or
[0045] the bottom portion of the liquid fuel tank is pressed
against the two-fluid spray nozzle to be brought into firm
contact.
[0046] A two-fluid spray burner of a ninth invention is the
two-fluid spray burner of the first invention, characterized in
that
[0047] the liquid fuel discharge holes are opened in the bottom
portion of the liquid fuel tank,
[0048] the burner characterized by further comprising:
[0049] a cylindrical first atomizing gas passage formed between the
side portion of the liquid fuel tank and an outer cylinder
surrounding a periphery of the side portion; and
[0050] a two-fluid spray nozzle provided at a lower end portion of
the outer cylinder, the two-fluid spray nozzle having: [0051] a
two-fluid converging space portion formed in center part under the
liquid fuel discharge holes and [0052] one or a plurality of spray
holes formed, leading to the two-fluid converging space
portion,
[0053] the burner characterized in that
[0054] the top surface of the two-fluid spray nozzle is formed as a
tapered surface portion which is tapered,
[0055] the undersurface of the bottom portion of the liquid fuel
tank is formed as a tapered surface portion which is tapered,
[0056] a plurality of supporting portions protrude on the side
portion of the liquid fuel tank, and each undersurface of the
supporting portions is formed as a tapered surface portion,
[0057] the liquid fuel tank is installed on the two-fluid spray
nozzle with the tapered surface portions of the supporting portions
being abutted and fitted to the tapered surface portion of the
two-fluid spray nozzle,
[0058] gap formed by the supporting portions between the tapered
surface portion of the liquid fuel tank and the tapered surface
portion of the two-fluid spray nozzle is a second atomizing gas
passage, and
[0059] the liquid fuel discharged from the liquid fuel discharge
holes to flow into the two-fluid converging space portion converges
at the two-fluid converging space portion with the atomizing gas
which flows down the first atomizing gas passage, passes through
atomizing gas passage portions between the supporting portions, and
flows through the second atomizing gas passage to be introduced to
the two-fluid converging space portion and is then sprayed together
with the atomizing gas from the spray holes.
[0060] A two-fluid spray burner of a tenth invention is the
two-fluid spray burner of any one of the second to ninth inventions
characterized in that the two-fluid converging space portion is a
reverse conical shape, and the spray holes are formed at a vertex
position of the reverse conical space.
[0061] A two-fluid spray burner of an eleventh invention is the
two-fluid spray burner of any one of the second to tenth
inventions, the burner characterized by further comprising a
cylindrical gas fuel passage formed between the outer cylinder and
a gas fuel supply tube surrounding a periphery of the outer
cylinder,
[0062] the burner characterized in that gas fuel flows down the gas
fuel passage and is sprayed from a lower end of the gas fuel
passage to be burned.
[0063] A two-fluid spray burner of a twelfth invention is the
two-fluid spray burner according to any one of the first to
eleventh inventions, characterized in that an end of the liquid
fuel supply tube is in contact with an inner peripheral surface of
the side portion of the liquid fuel tank.
[0064] The two-fluid spray burner of any one of the first and
second inventions may further include the following
configurations.
[0065] The two-fluid spray burner of a first configuration is the
two-fluid spray burner of any one of the first and second
inventions, which sprays liquid fuel from the two-fluid spray
nozzle of a two-fluid sprayer to the combustion space under the
two-fluid spray nozzle and burns the same, the burner characterized
by further comprising:
[0066] a cylindrical combustion air passage formed between the
two-fluid sprayer and a burner outer cylinder surrounding a
periphery of the two-fluid sprayer;
[0067] a shielding plate separating the combustion air passage and
the combustion space; and
[0068] a combustion air hole provided on an outer periphery of the
shielding plate, characterized in that
[0069] the combustion air which flows down the combustion air
passage is blocked by the shielding plate, introduced to the outer
periphery of the shielding plate to be kept away from the fuel
spray nozzle, and flow through the combustion air hole into the
combustion space.
[0070] The two-fluid spray burner of a second configuration is the
two-fluid spray burner of the first configuration, characterized in
that
[0071] a cylinder extending downward from a undersurface of the
shielding plate for delaying supply of combustion air is provided
to form different cylindrical combustion air passage between the
cylinder and the burner outer cylinder, the different combustion
air passage leading to the combustion air hole, and
[0072] after passing through the combustion air hole, the
combustion air flows down the different combustion air passage and
flows into the combustion space from a lower end of the different
combustion air passage.
[0073] The two-fluid spray burner of a third configuration is the
two-fluid spray burner of the second configuration, characterized
in that
[0074] one or a plurality of cylinders extending downward from the
undersurface of the shielding plate for preventing stagnation are
provided within the cylinder for delaying supply of the combustion
air.
[0075] The two-fluid spray burner of a fourth configuration is the
two-fluid spray burner of any one of the first to third
configuration, characterized in that
[0076] in the shielding plate, a plurality of other combustion air
holes are formed in a position inside the combustion air hole.
EFFECT OF THE INVENTION
[0077] According to the two-fluid spray burner of the first
invention, the two-fluid spray burner is provided with the liquid
fuel tank which includes the cylindrical side portion and the
bottom portion provided at the lower end of the side portion. The
liquid fuel tank stores the liquid fuel supplied from the liquid
fuel supply tube and discharges the stored liquid fuel from the
liquid fuel discharge holes which are opened in the side or bottom
portion thereof, below the liquid level of the stored liquid fuel.
The liquid fuel discharged from the liquid fuel discharge holes of
the liquid fuel tank is atomized with the atomizing gas and is
burned. Accordingly, in the two-fluid spray burner thus configured,
even when the liquid fuel is intermittently supplied from the
liquid fuel supply tube to the liquid fuel tank, the liquid fuel
stored in the liquid fuel tank is continuously discharged from the
liquid fuel discharge holes of the liquid fuel tank. In other
words, even when the supply flow rate of a pump of a liquid fuel
supply system is low and the liquid fuel is intermittently supplied
from the liquid fuel supply tube to the liquid fuel tank, the
liquid level of the liquid fuel stored in the liquid fuel tank
fluctuates a little up and down to cause the flow rate of the
liquid fuel discharged from the liquid fuel discharge hole to
fluctuate a little. The flow rate of supplied liquid fuel does not
fluctuate much unlike the conventional one. The liquid fuel can be
therefore stably supplied even when the flow rate of supplied
liquid fuel is low, thus achieving stable combustion is facilitated
and the possibility of producing unburned exhaust gas and causing
accidental fire is eliminated.
[0078] According to the two-fluid spray burner of the second
invention, the liquid fuel which is discharged from the liquid fuel
discharge holes to flow into the two-fluid converging space portion
converges with the atomizing gas which flows down the atomizing gas
passage and passes through the grooves at the atomizing gas
introduction portion to be introduced into the two-fluid converging
space portion and is then sprayed together with the atomizing air
from the spray holes. Accordingly, in the two-fluid spray burner
thus configured, the liquid fuel is well mixed with the atomizing
air whose flow speed is increased at the grooves (with the
horizontal speed component increased), at the two-fluid converging
space portion and is then sprayed from the spray holes of the
two-fluid spray nozzle. Compared to the case of not providing the
two-fluid converging space portion and grooves, therefore, the
spread angle of the sprayed liquid fuel is larger, and the liquid
fuel is surely atomized, thus improving the combustion
characteristics.
[0079] According to the two-fluid spray burner of the third
invention, the liquid fuel tank is installed on the atomizing gas
introduction portion with the tapered surface portion of the liquid
fuel tank abutted and fitted to the tapered surface portion of the
atomizing gas introduction portion. It is therefore easy to align
the central axes of the liquid fuel tank and two-fluid spray
nozzle. Accordingly, the liquid fuel tank is installed at the
center, and it is possible to equalize the width of the atomizing
gas passage in the circumferential direction and equalize the flow
of the atomizing gas in the atomizing gas passage in a
circumferential direction. This makes it possible to secure
symmetric properties of the liquid fuel sprayed from the spray hole
of the two-fluid spray nozzle (or symmetric properties of the
flame).
[0080] According to the two-fluid spray burner of the fourth
invention, the liquid fuel discharged from the liquid fuel
discharge hole to flow into the two-fluid converging space portion
converges at the two-fluid converging space portion with the
atomizing gas which flows down the atomizing gas passage and the
flows through the grooves at the bottom portion of the fuel tank to
be introduced to the two-fluid converging space portion and is then
sprayed together with the atomizing gas through the spray holes.
Accordingly, in the two-fluid spray burner thus configured, the
liquid fuel is well mixed with the atomizing gas whose flow speed
increased at the grooves (with the horizontal speed component
increased), at the two-fluid converging space portion and then
sprayed through the spray holes. Compared to the case of not
providing the two-fluid converging space portion and grooves,
therefore, the spread angle of the liquid fuel is larger, and the
liquid fuel is surely atomized, thus improving the combustion
characteristics.
[0081] Furthermore, the liquid fuel tank is installed on the
two-fluid spray nozzle with the tapered surface portion of the
liquid fuel tank being abutted and fitted to the tapered surface
portion of the two-fluid spray nozzle. It is therefore easy to
align the central axes of the liquid fuel tank and two-fluid spray
nozzle. Accordingly, the liquid fuel tank is installed at the
center, and it is possible to equalize the width of the atomizing
gas passage in the circumferential direction and thus equalize the
flow of the atomizing gas in the atomizing gas passage in the
circumferential direction. It is therefore possible to secure the
symmetric properties of the liquid fuel sprayed from the spray
holes of the two-fluid spray nozzle (or symmetric properties of
flame).
[0082] According to the two-fluid spray burner of the fifth
invention, the grooves of the atomizing gas introduction portion or
the grooves of the bottom portion of the liquid fuel tank are
formed along tangent directions of the circumference of the
two-fluid converging space portion in a top view. Accordingly, the
atomizing gas is swirled and mixed with the liquid fuel at the
two-fluid converging space portion, and the liquid fuel and
atomizing gas are thus mixed more surely. The liquid fuel sprayed
through the spray hole of the two-fluid spray nozzle can be
therefore surely atomized, thus improving the combustion
characteristics of the liquid fuel.
[0083] According to the two-fluid spray burner of the sixth
invention, the grooves of the atomizing gas introduction portion or
the grooves of the bottom portion of the liquid fuel tank are
formed along the radial directions of the two-fluid converging
space portion in a top view. The atomizing gas therefore collides
with the liquid fuel at the two-fluid converging space portion to
be mixed with the liquid fuel, and the liquid fuel and atomizing
gas are more surely mixed. Accordingly, the liquid fuel sprayed
from the spray holes of the two-fluid spray nozzle can be atomized
more surely, thus further improving the combustion characteristics
of the liquid fuel.
[0084] According to the two-fluid spray burner of the seventh
invention, the plurality of grooves of the atomizing gas
introduction portion or the plurality of grooves of the bottom
portion of the liquid fuel tank are formed at positions
rotationally symmetric around the central axis of the two-fluid
converging space portion. Accordingly, the distribution of the
liquid fuel sprayed from the spray holes of the two-fluid spray
nozzle in the circumferential direction can be equalized, thus
improving the combustion characteristics of the liquid fuel.
[0085] According to the two-fluid spray burner of the eighth
invention, the two-fluid spray burner is provided with the press
member pressing the liquid fuel tank downward. The bottom portion
of the liquid fuel tank is thus pressed against the atomizing gas
introduction portion of the two-fluid spray nozzle to be brought
into firm contact, or the bottom portion of the liquid fuel tank is
thus pressed against the two-fluid spray nozzle to be brought into
firm contact. Accordingly, the undersurface of the bottom portion
of the fuel tank and the top surface of the atomizing gas
introduction portion are brought into firm contact. In other words
the tapered surface portion of the liquid fuel tank and the tapered
surface portion of the atomizing gas introduction portion or the
tapered surface portion of the liquid fuel tank and the tapered
surface portion of the two-fluid spray nozzle are brought into firm
contact, thus preventing formation of gap between these contact
surfaces. It is therefore possible to prevent the atomizing gas
from flowing through portions other than the grooves and allow the
effect of wide spraying by the grooves to be sufficiently
exerted.
[0086] According to a two-fluid spray burner of the ninth
invention, the liquid fuel discharged from the liquid fuel
discharge holes to flow into the two-fluid converging space portion
converges at the two-fluid converging space portion with the
atomizing gas which flows down the first atomizing gas passage,
passes through the atomizing gas passage portions between the
supporting portions, and then flows through the second atomizing
gas passage to be introduced to the two-fluid converging space
portion and is then sprayed together with the atomizing gas from
the spray holes. Accordingly, in the two-fluid spray burner thus
configured, the liquid fuel is mixed with the atomizing gas at the
two-fluid converging space portion and is then sprayed from the one
of plurality of spray holes of the two-fluid spray nozzle. Compared
to the case of not providing the two-fluid converging space
portion, therefore, the spread angle of the sprayed liquid fuel is
larger, and the liquid fuel is surely atomized, thus improving the
combustion characteristics.
[0087] According to the two-fluid spray burner of the tenth
invention, the two-fluid converging space portion is a reverse
conical shape, and the spray holes are formed at the vertex
position of the reverse conical space. Accordingly, the liquid fuel
and atomizing gas can be more surely mixed at the two-fluid
converging space portion. The liquid fuel sprayed from the spray
holes is more surely atomized, thus further improving the
combustion characteristics of the liquid fuel.
[0088] According to the two-fluid spray burner of the eleventh
invention, the two-fluid spray burner includes a cylindrical gas
fuel passage formed between the outer cylinder and the gas fuel
supply tube surrounding a periphery of the outer cylinder. The gas
fuel flows down the gas fuel passage and is then sprayed from the
lower end of the gas fuel passage to be burned. Accordingly, in the
two-fluid spray burner thus configured, the gas fuel sprayed from
the cylindrical gas fuel passage is uniform in the circumferential
direction. It is therefore possible to improve the combustion
characteristics, thus exerting a flame holding effect by the gas
fuel when the liquid fuel is supplied at a low flow rate, for
example.
[0089] According to the two-fluid spray burner of the twelfth
invention, the end portion of the liquid fuel supply tube is in
contact with the inner peripheral surface of the side potion of the
liquid fuel tank, so that the liquid fuel flows down the inner
peripheral surface even when the flow rate of the liquid fuel
discharged from the liquid fuel supply tube is low. It is therefore
possible to further stabilize the discharge of the liquid fuel from
the liquid fuel discharge hole. In other words, when the liquid
fuel falls in droplets, the liquid level of the liquid fuel stored
in the liquid fuel tank greatly fluctuates. In the case where the
liquid level is very low, there might be a case where the liquid
fuel discharge holes are temporarily exposed to stop the discharge
of the liquid fuel. However, allowing the liquid fuel to flow down
the inner peripheral surface of the liquid fuel tank can prevent
occurrence of such a disadvantage.
[0090] According to the two-fluid spray burner of the first
configuration, the combustion air flowing down the combustion air
passage is blocked by the shielding plate and then introduced to
the outer periphery of the shielding plate to be kept away from the
fuel spray nozzle. The combustion air then passes through the
combustion air hole and flows into the combustion space.
Accordingly, only a part of the combustion air is mixed at the
combustion space with the fuel sprayed from the fuel spray nozzle
and used for combustion of the fuel. The residual combustion air
further flows down and is mixed with combustion exhaust gas
produced by the combustion. It is therefore possible to achieve
proper mixture of the combustion air and fuel through one supply of
the combustion air (with one step) and produce a large amount of
combustion exhaust gas without exceedingly cooling flame. It is
possible to achieve a burner such as a two-fluid spray burner which
is capable of producing a large amount of combustion exhaust gas
with a simple configuration and does not generate unburned gas and
cause accidental fire.
[0091] Moreover, the combustion air is caused to flow into the
combustion space at the position away from the fuel spray nozzle by
the shielding plate. Accordingly, the position where a part of the
combustion air is supplied to fuel can be set downward away from
the shielding plate. The position of flame is also set downward
away from the shielding plate, thus preventing adherence of soot to
the undersurface of the shielding plate. A lot of soot sticking to
the undersurface of the shielding plate may cause disadvantages
such as clogging of the fuel spray nozzle due to the soot and
abnormal heating of the fuel spray due to the soot absorbing
radiation heat from flame. However, by preventing adherence of soot
to the undersurface of the shielding plate as described above, such
disadvantages can be prevented from occurring.
[0092] Moreover, according to the two-fluid spray burner of the
second mode, the cylinder extending downward from the undersurface
of the shielding plate for delaying supply of the combustion air is
provided, and the additional cylindrical combustion air passage
leading to the combustion air hole is formed between the cylinder
and the burner outer cylinder. The combustion air which flows
through the combustion air hole is thus allowed to flow down the
different combustion air passage and then flow into the combustion
space from the lower end of the combustion air passage. In this
configuration, it is therefore possible to delay supply of a part
of the combustion air to the fuel sprayed from the fuel spray
nozzle. In other words, the position where a part of the combustion
air is supplied to the fuel can be set downward away from the
shielding plate. Accordingly, the position of flame is set downward
away from the shielding plate, thus preventing adherence of soot to
the undersurface of the shielding plate. The operational effect of
setting the position where a part of the combustion air is supplied
to the fuel downward away from the shielding plate can be also
obtained by provision of only the shielding plate as described
above. However, as described in the second invention, by providing
the cylinder for delaying supply of the combustion air, the
position where a part of the combustion air is supplied to the fuel
can be more surely set downward away from the shielding plate.
[0093] In the aforementioned first configuration, when the
shielding plate cannot be made so large because of restriction on
size of the burner and the like and the distance between the fuel
spray nozzle and combustion air hole cannot be made long enough,
the amount of the part of the combustion air supplied to the fuel
is too much, and the flame could be excessively cooled. On the
contrary, by providing the cylinder for delaying supply of
combustion air like the second configuration, the position where
the part of the combustion air is supplied to the liquid fuel can
be set downward away from the shielding plate, and the part of the
combustion air supplied to the fuel can be reduced to a proper
amount. Accordingly, provision of the cylinder like the second
invention is effective in such a view. By providing the cylinder,
the shielding plate can be reduced in size, and the burner can be
miniaturized.
[0094] According to the two-fluid spray burner of the third
configuration, one or plurality of the cylinders extending downward
from the undersurface of the shielding plate for preventing
stagnation are provided within the cylinder for delaying supply of
combustion air. Accordingly, stagnation (convection) of the fuel
can be prevented from occurring near the undersurface of the
shielding plate by the cylinder for preventing stagnation. It is
therefore possible to prevent the fuel stagnating near the
undersurface of the shielding plate from catching fire and adhering
of soot to the undersurface of the shielding plate.
[0095] According to the two-fluid spray burner of the fourth
configuration, one or plurality of additional combustion air holes
are formed in the shielding plate portion inside the one or
plurality of combustion air holes, so that a part of the combustion
air flows through these additional combustion air holes.
Accordingly, such a flow of the combustion air can suppress
stagnation of the combustion air occurring near the undersurface of
the shielding plate, thus preventing adherence of soot to the
shielding plate. Moreover, the cool combustion air flows near the
fuel spray nozzle through the additional combustion air holes. It
is therefore possible to obtain a cooling effect, with the
combustion air, on the fuel spray nozzle which tends to be
excessively heated by radiation heat from flame.
BRIEF DESCRIPTION OF DRAWINGS
[0096] FIG. 1 is a longitudinal sectional view showing a structure
of a two-fluid spray burner according to Embodiment 1 of the
present invention.
[0097] FIG. 2 is a transverse sectional view taken along a line A-A
of FIG. 1.
[0098] FIG. 3 is a transverse sectional view taken along a line B-B
of FIG. 1.
[0099] FIG. 4(a) is an enlarged longitudinal sectional view showing
a two-fluid sprayer provided for the two-fluid spray burner of FIG.
1, and FIG. 4(b) is a transverse sectional view taken along a line
C-C of FIG. 4(a).
[0100] FIG. 5(a) is an enlarged longitudinal sectional view showing
lower part of the two-fluid sprayer, and FIG. 5(b) is a top view (a
view in the direction of arrows D of FIG. 5 (a)) showing a
two-fluid spray nozzle provided for the two-fluid sprayer.
[0101] FIG. 6(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 2 of the present invention, and FIG.
6(b) is a top view (a view in the direction of arrows E of FIG.
6(a)) showing a two-fluid spray nozzle provided for the two-fluid
sprayer.
[0102] FIG. 7(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 3 of the present invention, and FIG.
7(b) is a top view (a view in the direction of arrows F of FIG.
7(a)) showing a two-fluid spray nozzle provided for the two-fluid
sprayer.
[0103] FIG. 8(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 4 of the present invention (a
longitudinal section view taken along the G-G line of FIG. 8(b));
FIG. 8(b) is a bottom view (a view in the direction of an arrow H
of FIG. 8(a)) showing a liquid fuel tank provided for the two-fluid
sprayer; FIG. 8(c) is a view in the direction of an arrow I of FIG.
8(b); and FIG. 8(d) is a transverse sectional view taken along a
line J-J of FIG. 8(a).
[0104] FIG. 9(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 5 of the present invention (a
cross-sectional view taken along a line K-K of FIG. 9(b)); FIG.
9(b) is a bottom view (a view in the direction of an arrow L of
FIG. 9(a)) showing a liquid fuel tank provided for the two-fluid
sprayer; and FIG. 9(c) is a transverse sectional view taken along a
line M-M of FIG. 9(a).
[0105] FIG. 10(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 6 of the present invention. FIG.
10(b) is a transverse sectional view taken along a line L-L of FIG.
10(b).
[0106] FIG. 11 is a longitudinal sectional view showing
configuration of a two-fluid spray burner according to Embodiment 7
of the present invention.
[0107] FIG. 12 is a transverse sectional view taken along a line
M-M of FIG. 11.
[0108] FIG. 13 is a system diagram schematically showing a fuel
cell power generation system according to Embodiment 8 of the
present invention.
[0109] FIG. 14(a) is a view showing liquid fuel intermittently
discharged from an end of a liquid fuel supply tube in a
conventional two-fluid spray burner, and FIG. 14(b) is a view
showing great fluctuations in flow rate of supplied liquid fuel in
the conventional two-fluid spray burner.
EXPLANATION OF REFERENCE NUMERALS
[0110] 11, TWO-FLUID SPRAY BURNER; 12, TWO-FLUID SPRAYER; 13,
COMBUSTION SPACE; 14, GAS FUEL PASSAGE; 15, COMBUSTION AIR PASSAGE;
16, FIRST CYLINDER; 17, SECOND CYLINDER; 18, PLATE; 19, LIQUID FUEL
TANK; 20, SIDE PORTION, 20a, INNER PERIPHERAL SURFACE; 20b, OUTER
PERIPHERAL SURFACE; 21, BOTTOM PORTION; 21a, INNER SURFACE (TOP
SURFACE); 21b, OUTER SURFACE (UNDERSURFACE); 21b-1, OUTSIDE
PORTION; 21b-2, INSIDE PORTION; 22, LIQUID FUEL DISCHARGE HOLE; 23,
LIQUID LEVEL; 24, LIQUID FUEL; 24A, CONTOUR; 25, LIQUID FUEL SUPPLY
TUBE; 25A, END PORTION (BOTTOM END); 26, WASHER; 27, SPRAYER OUTER
CYLINDER; 27A, LOWER END PORTION; 27B, UPPER END PORTION; 28,
ATOMIZING AIR PASSAGE; 29, AIR INLET HOLE; 30, ATOMIZING AIR SUPPLY
TUBE; 30A, END PORTION; 31, CAP; 32, 33, THREAD PORTION; 31A, LOWER
PORTION; 31B, STEP PORTION; 34, O-RING; 35, WASHER; 36, COIL
SPRING; 37, ATOMIZING GAS INTRODUCTION PORTION; 37a, TOP SURFACE;
37b, INNER PERIPHERAL SURFACE; 38, TWO-FLUID SPRAY NOZZLE; 38a,
INNER SURFACE (TOP SURFACE); 39, NOZZLE BODY; 40, GROOVE; 41,
SPACE; 42 SPACE (RECESS); 43, TWO-FLUID CONVERGING SPACE PORTION;
44, SPRAY HOLE; 45, GAP; 46, ATOMIZING AIR; 47, GAS FUEL SUPPLY
TUBE; 48, BURNER OUTER CYLINDER; 48a, INNER PERIPHERAL SURFACE; 49,
GAS FUEL; 50, COMBUSTION AIR; 51, PROTRUSION; 52, COMBUSTION AIR
PASSAGE HOLE; 53, COMBUSTION AIR PASSAGE; 54, SPARK PLUG; 61,
GROOVE; 81, GROOVE; 91, SUPPORT PORTION; 91a, UNDERSURFACE; 91a-1,
OUTSIDE PORTION; 92, ATOMIZING AIR PASSAGE; 93, ATOMIZING AIR
PASSAGE PORTION; 101, COMBUSTION AIR PASSAGE HOLE; 111, REFORMER;
112, COMBUSTION FURNACE; 113 FUEL CELL
BEST MODES FOR CARRYING OUT THE INVENTION
[0111] Hereinafter, a description is given of embodiments of the
present invention with reference to the drawings.
Embodiment 1
[0112] FIG. 1 is a longitudinal sectional view showing a
configuration of a two-fluid spray burner according to Embodiment 1
of the present invention. FIG. 2 is a transverse sectional view
taken along a line A-A of FIG. 1. FIG. 3 is a transverse sectional
view taken along a line B-B of FIG. 1. FIG. 4(a) is an enlarged
longitudinal sectional view showing a two-fluid sprayer provided in
the two-fluid spray burner of FIG. 1, and FIG. 4(b) is a transverse
sectional view taken along a line C-C of FIG. 4(a). FIG. 5(a) is an
enlarged longitudinal sectional view showing lower part of the
two-fluid sprayer, and FIG. 5(b) is a top view (a view in the
direction of arrows D) showing a two-fluid spray nozzle provided
for the two-fluid sprayer.
[0113] Based on FIGS. 1 to 3, a schematic description is given of a
two-fluid spray burner 11 of Embodiment 1. The two-fluid spray
burner 11 includes a burner outer cylinder 48. Within the burner
outer cylinder 48, a two-fluid sprayer 12 is placed in upper
central part, and a combustion space 13 is under the two-fluid
sprayer 12. A gas fuel supply passage 14 is formed around the
two-fluid sprayer 12, and around the gas fuel supply passage 14, a
combustion air supply passage 15 is formed. The combustion air
supply passage 15 and combustion space 13 are partitioned with a
plate 18 as a shielding plate. On an undersurface of the plate 18,
a first cylinder 16 as a cylinder for delaying supply of combustion
air and a second cylinder 17 as a cylinder for preventing
stagnation are provided.
[0114] Based on FIGS. 4 and 5, a description is given of a
configuration of the two-fluid sprayer 12 in detail. Note that, the
two-fluid sprayer 12 sprays two fluids which are liquid fuel and
atomizing gas (atomizing air), in other words, atomizes the liquid
fuel with atomizing gas and sprays the same.
[0115] As shown in FIGS. 4 and 5, the two-fluid sprayer 12 has a
liquid fuel tank 19 built-in. The liquid fuel tank 19 has a
structure including a cylindrical side portion (a body portion) 20
and a bottom portion 21 provided at a bottom end of the side
portion 20. Within the liquid fuel tank 19, liquid fuel 24 for
burner combustion is stored, and a fine liquid fuel discharge hole
22 is opened at the center of the bottom portion 21 of the liquid
fuel tank 19. The liquid fuel discharge hole 22 is positioned below
a liquid level 23 of the liquid fuel 24 stored in the liquid fuel
tank 19.
[0116] Specifically, the liquid fuel 24 supplied from a liquid fuel
supply tube 25 is once stored in the liquid fuel tank 19. The
stored liquid fuel 24 is discharged from the liquid fuel tank 19
through the liquid fuel discharge hole 22 at the bottom. At this
time, height of the liquid level 23 of the liquid fuel 24 stored in
the liquid fuel tank 19 (height from an inner surface 21a of the
bottom portion 21 to the liquid level 23) is a height which
provides a liquid column head (described in detail later)
corresponding to a pressure loss of the liquid fuel 24 flowing
through the liquid fuel discharge hole 22. Examples of the liquid
fuel 24 for burner combustion can be kerosene, heavy oil, alcohol,
ether and the like.
[0117] In the liquid fuel supply tube 25, an end portion (a lower
end portion) 25A is inserted downward from an upper end of the
liquid fuel tank 19 into the liquid fuel tank 19 and is provided to
be positioned in central part of the liquid fuel tank 19 above the
liquid level 23. The base end of the liquid fuel supply tube 25 is
connected to a liquid fuel supply pump of an unillustrated liquid
fuel supply system.
[0118] As indicated by a dashed-dotted line in FIG. 5(a), the end
portion 25A of the liquid fuel supply tube 25 may be in contact
with an inner peripheral surface 20a of the side portion 20 of the
liquid fuel tank 19. When the liquid fuel 24 is supplied at a low
flow rate, the liquid fuel 24 drops in droplets as illustrated in
the drawing, if the end portion 25A of the liquid fuel supply tube
25 is spaced from the inner peripheral surface 20a of the liquid
fuel tank 19. On the other hand, the liquid fuel 24 flows down the
inner peripheral surface 20a, if the end portion 25A of the liquid
fuel supply tube 25 is in contact with the inner peripheral surface
20a of the liquid fuel tank 19.
[0119] The liquid fuel tank 19 is provided within the cylindrical
sprayer outer cylinder 27 in a concentric manner with the sprayer
outer cylinder 27. In the liquid fuel tank 19, cylindrical space
between the side portion 20 and sprayer outer cylinder 27 is an
atomizing air passage 28 serving as an atomizing air passage. In
the sprayer outer cylinder 27, an air inlet hole 29 is opened. The
air inlet hole 29 is connected to an end portion 30A of the
atomizing air supply tube 30. The base side of the atomizing air
supply tube 30 is connected to an air supply blower of an
unillustrated atomizing air supply system.
[0120] The two-fluid spray nozzle 38 is attached to a lower end
portion 27A of the sprayer outer cylinder 27 and positioned under
the liquid fuel tank 19. In other words, the two-fluid sprayer 12
is configured to include the liquid fuel tank 19, as a buffer for
reducing fluctuations in flow rate of supplied fuel liquid,
interposed between the liquid fuel supply tube 25 and two-fluid
spray nozzle 38. The two-fluid spray nozzle 38 includes a
disk-shaped nozzle body 39 and an atomizing air introduction
portion 37 formed on the nozzle body 39 as an atomizing gas
introduction portion. The two-fluid spray nozzle 38 is fixed to the
lower end portion 27A of the sprayer outer cylinder 27 by fixing
means such as welding, with the peripheral edge of the top surface
of the nozzle body 39 abutted on the lower end surface of the
sprayer outer cylinder 27 and with the atomizing air introduction
portion 37 fitted into the lower end portion 27A of the sprayer
outer cylinder 27.
[0121] The atomizing air introduction portion 37 is formed into a
ring-shape and includes a space 41 with a circular plan view (top
view) in the central part. The nozzle body 39 includes a reverse
conical space (recess) 42 in the central part and a fine spray hole
44 opened at the center (at a vertex position of the reverse
conical space 42). The space 41 of the atomizing air introduction
portion 37 is continuous to the space 42 of the nozzle body 39, and
the spaces 41 and 42 constitute a two-fluid converging space
portion 43. Specifically, the two-fluid converging space portion 43
has a tapered structure with a circular top view and a diameter
gradually reducing towards the spray hole 44. In the atomizing air
introduction portion 37, grooves (slits) 40 are formed at two
places in the circumference direction thereof. These grooves 40 are
swirling type and are extended in tangent directions of the
circumference of the two-fluid converging space portion 43 in a top
view. Moreover, the grooves 40 are formed at positions rotationally
symmetric (at equal intervals in the circumferential directions)
around a central axis of the two-fluid converging space portion 43
(a central axis of the spray hole 44 in the example of the
drawing).
[0122] On the other hand, the upper end portion 27B of the sprayer
outer cylinder 27 is closed with a cap 31 as a closing member to
prevent leak of the atomizing air from the inside of the sprayer
outer cylinder 27 to the outside. The cap 31 is attached to the
upper end portion 27B of the sprayer outer cylinder 27 by screwing
a thread portion 33 formed in an outer peripheral surface of a
lower portion 31A of the cap 31 to a thread portion 32 formed in an
inner peripheral surface of the upper end portion 27B of the
sprayer outer cylinder 27. Between a step portion 31B of the cap 31
and the upper end portion 27B of the sprayer outer cylinder 27, an
O ring 34 is interposed to reliably prevent leak of the atomizing
air. The end portion 25A of the liquid fuel supply tube 25
penetrates through the cap 31, passes through the inside of the
sprayer outer cylinder 27 (the inside of a coil spring 36), and
then inserted into the liquid fuel tank 19 through an upper end of
the liquid fuel tank 19.
[0123] Between a washer 35 provided on an undersurface of the cap
31 and a washer 26 provided on an upper end of the liquid fuel tank
19, the coil spring 36 as a press member is interposed. The coil
spring 36 presses the liquid fuel tank 19 downward to press an
outer surface (undersurface) 21b of the bottom portion 21 of the
liquid fuel tank 19 against the top surface 37a of the atomizing
air introduction portion 37. Accordingly, the outer surface
(undersurface) 21b of the bottom portion 21 and top surface 37a of
the two-fluid nozzle 38 (atomizing air introduction portion 37) in
contact with each other are firmly joined to each other, thus
preventing formation of gap between these contact surfaces 21b and
37a.
[0124] Between the washer 26 and liquid fuel supply tube 25, a gap
45 is provided, through which internal space of the liquid fuel
tank 19 and internal space of the sprayer outer cylinder 27 outside
of the liquid fuel tank 19 communicate with each other. In other
words, the upper end of the liquid fuel tank 19 is opened to the
internal space of the sprayer outer cylinder 27, and the internal
space of the liquid fuel tank 19 and the upper end portion
(upstream portion) of the atomizing air passage 28 communicate with
each other. Accordingly, pressure of atomizing air 46 flowing from
the air inlet hole 29 into the sprayer outer cylinder 27 and then
into the atomizing air passage 28 acts on the liquid level 23 of
the liquid fuel 24 stored in the liquid fuel tank 19.
[0125] In this two-fluid sprayer 12, when the liquid fuel 24 for
burner combustion which is fed from the liquid fuel supply pump
through the liquid fuel supply tube 25 is discharged from the end
portion 25A of the liquid fuel supply tube 25 (discharged
continuously in the case of comparatively high flow rate and
intermittently discharged in the case of comparatively low flow
rate as illustrated in FIG. 5(a)), the liquid fuel 24 is once
stored in the liquid fuel tank 19. The liquid fuel 24 stored in the
liquid fuel tank 19 is continuously discharged from the liquid fuel
discharge hole 22 of the bottom portion 21 of the liquid fuel tank
19 into the two-fluid converging space portion 43. In the case
where the liquid fuel is intermittently discharged from the end
portion 25A of the liquid fuel supply tube 25, a phenomenon is
repeated in which the liquid level 23 rises while the liquid fuel
24 is discharged from the end portion 25A of the liquid fuel supply
tube 25 and falls while the liquid fuel 24 is not discharged from
the end portion 25A of the liquid fuel supply tube 25. Though the
flow rate of the liquid fuel 24 discharged from the liquid fuel
discharge hole 22 varies according to such fluctuations in liquid
level, such variations in flow rate are much smaller than the
conventional variations in flow rate.
[0126] On the other hand, the atomizing air 46 fed from an air
supply pump through the atomizing air supply tube 30 flows into the
sprayer outer cylinder 27 through the air inlet hole 29 and flows
down the atomizing air passage 28 between the liquid fuel tank 19
and sprayer outer cylinder 27. Thereafter, the atomizing air 46
flows through the grooves 40 of the atomizing air introduction
portion 37 of the two-fluid spray nozzle 38 to increase flow rate
and is then introduced to the two-fluid converging space portion
43. The atomizing air 46 becomes swirling flow in the two-fluid
converging space portion 43 and converges with (is mixed with) the
liquid fuel 24 discharged from the liquid fuel discharge hole 22 of
the liquid fuel tank 19. The liquid fuel 24 is therefore well mixed
with the atomizing air 46 and is atomized with the atomizing air 46
to be sprayed together with the atomizing air 46 from the spray
hole 44 of the two-fluid spray nozzle 38 into a combustion space 13
(flame) for combustion. The initial ignition to the atomized liquid
fuel 24 is performed by a spark plug 54.
[0127] Herein, the liquid column head H of the liquid fuel 24
stored in the liquid fuel tank 19 is described in detail. The
liquid column head H can be calculated by the following equation
based on a pressure loss .DELTA.P (hole) of the liquid fuel 24
flowing through the liquid fuel discharge hole 22, a kinetic energy
E of the liquid fuel 24 discharged from the liquid fuel discharge
hole 22, and a pressure loss .DELTA.Pair of the atomizing air 49 at
the grooves 40.
Liquid Column Head H=Pressure Loss .DELTA.P (hole)+Kinetic Energy
E-Pressure Loss .DELTA.Pair
[0128] The kinetic energy E can be calculated by the following
equation based on flow velocity v of the liquid fuel 24 and density
.rho. of the liquid fuel 24.
Kinetic Energy=.rho.v.sup.2/2
[0129] Moreover, the height of the liquid level 23 of the liquid
fuel 24 stored in the liquid fuel tank 19 varies with the flow rate
of the liquid fuel 24 supplied to the liquid fuel tank 19 through
the liquid fuel supply tube 25. In other words, the liquid level 23
rises when the output of the fuel supply pump is controlled to
increase the flow rate of the liquid fuel 24 supplied and falls
when the flow rate of the liquid fuel 24 is reduced. Accordingly,
the liquid fuel tank 19 is configured to have a height
corresponding to changes in height of the liquid level 23 according
to a predetermined regulation range of the flow rate of the
supplied liquid fuel 24.
[0130] Moreover, the liquid fuel 24 is sprayed in a cone shape from
the spray hole 44 as illustrated in FIG. 5(a). The spread of the
spray (spray angle) is determined by a cross-sectional area of the
grooves 40 (or flow speed of the atomizing air 46 flowing through
the grooves 40), size of the spray hole 44 (or hole diameter), and
the like.
[0131] Next, a description is given of the configuration other than
the two-fluid sprayer 12 in detail. As shown in FIGS. 1 to 3, a
cylindrical gas fuel supply tube 47 is provided so as to surround
the periphery of the sprayer outer cylinder 27. The gas fuel supply
tube 47 is concentrically provided with the sprayer outer cylinder
27, and cylindrical space between the gas fuel supply tube 47 and
sprayer outer cylinder 27 is a gas fuel passage 14. Gas fuel 49 for
burner combustion supplied from a gas fuel supply system flows down
the gas fuel passage 14 to be sprayed from the lower end of the gas
fuel passage 14 into the combustion space 13 for combustion. The
liquid fuel 24 and the gas fuel 49 may be burned separately or
simultaneously. Examples of the gas fuel 49 for burner combustion
are methane, ethane, propane, butane, diethyl ether, and hydrogen.
Furthermore, in the case of using the two-fluid spray burner 11 as
a heat source of a reformer, the gas fuel 49 may be residual
reformed gas not used for power generation in a fuel cell and
returned to the two-fluid spray burner 11 (see FIG. 13).
[0132] The burner outer cylinder 48 is cylindrical and surrounds
the periphery of the gas fuel supply tube 47. The burner outer
cylinder 48 and gas fuel supply tube 47 are provided
concentrically, and cylindrical space between the burner outer
cylinder 48 and gas fuel supply tube 47 is a first combustion air
passage 15. Accordingly, the combustion air 50 supplied from an air
supply blower of the combustion air supply system flows down the
combustion air passage 15.
[0133] Between the lower end portion of the combustion air passage
15, that is a lower end portion of the gas fuel supply tube 47, and
the lower end portion of the burner outer cylinder 48, a plate 18
is provided. The plate 18 is a ring-shaped plate and separates the
combustion air passage 15 and combustion space 13. In the example
of the drawings, the plate 18 is provided at substantially the same
height as that of the two-fluid spray nozzle 38, but it is not
limited to this and may be provided at a position higher than that
of the two-fluid spray nozzle 38. However, if the plate 18 is
provided at a higher position, the first and second cylinders 16
and 17 need to be made longer than those of the example of the
drawing. Accordingly, providing the plate 18 at the same height as
that of the two-fluid spray nozzle 38 like the example of the
drawing costs the least, which is reasonable.
[0134] The inner peripheral surface of the plate 18 is fixed to the
outer peripheral surface of the gas fuel supply tube 47 by fixing
means such as welding. In the outer peripheral surface of the plate
18, a plurality of protrusions 51 (four protrusions in the example
of FIG. 2) are formed. End surfaces of the protrusions 51 are fixed
to the inner peripheral surface of the burner outer cylinder 48 by
fixing means such as welding. Accordingly, part between the gas
fuel supply tube 47 and the vicinity of the burner outer cylinder
48 is closed by the plate 18. However, on the outer periphery of
the plate 18, gaps are formed between the outer peripheral surface
of the plate 18 and the inner peripheral surface 48a of the burner
outer cylinder 48 by the protrusions 51. These gaps are combustion
air holes 52. In other words, the combustion air passage 15 and
combustion space 13 communicate with each other through these
combustion air holes 52.
[0135] Accordingly, after flowing down the combustion air passage
15, the combustion air 50 is blocked by the plate 18 to be
introduced to the outer peripheral side of the plate 18, which is
away from the two-fluid spray nozzle 38 (spray hole 44) and flows
through the combustion air holes 52 into the combustion space
13.
[0136] Moreover, the first cylinder 16 extending downward and the
second cylinder 17 extending downward, the second cylinder 17 being
provided inside the first cylinder 16, are fixed to the
undersurface of the plate 18 by fixing means such as welding. The
first cylinder 16 is located in a position inner to the combustion
air holes 52 and arranged concentrically with the burner outer
cylinder 48. The cylindrical space between the burner outer
cylinder 48 and the first cylinder 16 is a second combustion air
passage 53.
[0137] Accordingly, after flowing down the first combustion air
passage 15 and passing through the combustion air hole 52, the
combustion air 50 further flows down the second combustion air
passage 53. The combustion air 50 is discharged from the lower end
of the combustion air passage 53 and spreads over the combustion
space 13. Accordingly, a part of the combustion air 50 discharged
from the combustion air passage 53 (for example, about 30% of the
entire combustion air 50) is supplied to (mixed with) the liquid
fuel 24 sprayed from the two-fluid sprayer 12 (the two-fluid spray
nozzle 38) at a position downward away from the plate 18 and used
in combustion of the liquid fuel 24. The amount of the combustion
air 50 mixed with the liquid fuel 24 is set so that an average of
the air ratio is not more than 1.5, for example. The residual of
the combustion air 50 discharged from the combustion air passage 53
(for example, about 70% of the entire combustion air 50) further
flows down and is mixed with combustion exhaust gas produced by the
combustion, thus producing a large amount of combustion exhaust
gas.
[0138] The first cylinder 16 is installed for the purpose of
delaying supply of a part of the combustion air 50 to the atomized
liquid fuel 24, that is, supplying the combustion air 50 to the
atomized liquid fuel 24 at the position downward away from the
plate 18. Thus, the plate 18 is kept away of the flame and
prevented from being sooted. The length of the first cylinder 16,
that is the end position (bottom end) of the first cylinder 16 may
be properly set based on a relation with size of the plate 18
(distance between the spray hole 44 of the two-fluid spray nozzle
38 and the combustion air hole 52).
[0139] In other words, even without the first cylinder 16 but only
with the plate 18 and the combustion air hole 52 in the outer
periphery of the plate 18, a part of the combustion air 50 passed
through the combustion air hole 51 is supplied to the atomized
liquid fuel 24 at a position downward away from the plate 18. The
longer the distance between the spray hole 44 and the combustion
air hole 52 is, the farther, from the plate 18, the position where
the part of the combustion air 50 is supplied to the atomized
liquid fuel 24 is. If the plate 18 is increased in size to increase
the distance between the spray hole 44 and the combustion air hole
52, the two-fluid spray burner 11 is increased in diameter.
[0140] On the other hand, when the distance between the spray hole
44 and the combustion air hole 52 is limited by the limitation in
size of the two-fluid spray burner 11, the supply of the part of
the combustion air 50 to the atomized liquid fuel 24 cannot be
delayed enough in some cases only by providing the plate 18 and
combustion air hole 51. In such a case, provision of the first
cylinder 16 as illustrated in the drawing is very effective. In
this case, as the distance between the spray hole 44 and the
combustion air hole 52 is reduced, the first cylinder 16 is
extended downward. However, to prevent interference between the
first cylinder 16 and sprayed liquid fuel 24, the end (lower end)
of the first cylinder 16 needs to be positioned outside of (above)
a contour 24A of the sprayed liquid fuel 24. In other words, the
end (lower end) of the first cylinder 16 cannot be extended more
than the contour 24A of the sprayed liquid fuel 24.
[0141] If the distance between the spray hole 44 and the combustion
air hole 52 is reduced, the installation position of the first
cylinder 16 becomes closer to the spray hole 44, and the distance
between the plate 18 and contour 24A of the atomized liquid fuel 24
is reduced. The first cylinder 16 therefore cannot be made so long.
The distance between the spray hole 44 and the combustion air hole
52 and the length of the first cylinder 16 (including necessity of
the first cylinder 16) may be properly determined in view of such
restrictions.
[0142] The second cylinder 17 is positioned inside the first
cylinder 16 and is provided concentrically with the first cylinder
16. The second cylinder 17 is provided for the purpose of
preventing stagnation (convection) of the atomized liquid fuel 24
from occurring near the plate 18. Thus, the plate 18 is kept away
of the flame and prevented from being sooted. Accordingly, the
second cylinder 17 is extended downward as much as possible.
However, to prevent interference between the second cylinder 17 and
atomized liquid fuel 24, the end (lower end) of the second cylinder
17 needs to be positioned outside of (above) the contour 24A of the
atomized liquid fuel 24. In other words, the end (lower end) of the
second cylinder 17 also can only be extended to the contour 24A of
the atomized liquid fuel 24 at maximum.
[0143] For example, as shown in FIG. 1, length L2 between the end
(bottom end) of the two-fluid spray nozzle 38 (spray hole 44) and
the end (bottom end) of the second cylinder 17 needs to satisfy
0<L2<L1 tan .theta.. Herein, L1 is the distance between the
spray hole 44 of the two-fluid spray nozzle 38 and the second
cylinder 17, and .theta. is an angle between the contour 24A of the
sprayed liquid fuel 24 and the horizontal line thereof. The entire
length of the second cylinder 17 is L2 added to length between the
undersurface of the plate 18 and the end (lower end) of the
two-fluid spray nozzle 38 (spray hole 44). Such a condition is also
applied to length between the end (lower end) of the two-fluid
spray nozzle 38 (spray hole 44) and the end (lower end) of the
second cylinder 17 and the entire length of the first cylinder 16.
The distance between the spray hole 44 of the two-fluid spray
nozzle 38 and the second cylinder 16 is configured to be for
example, not less than 50 or 60 times the diameter of the spray
hole 44 (about 1 mm, for example).
[0144] As described above, the two-fluid spray burner 11 of present
Embodiment 1 is provided with the liquid fuel tank 19 which
includes the cylindrical side portion 20 and the bottom portion 21
provided at the lower end of the side portion 20 and stores the
liquid fuel 24 supplied from the liquid fuel supply tube 25. The
liquid fuel tank 19 is configured to allow the stored liquid fuel
24 to be discharged from the liquid fuel discharge hole 22, in the
bottom portion 21, which is opened below the liquid level of the
stored liquid fuel 24. The liquid fuel 24 discharged from the
liquid fuel discharge hole 22 of the liquid fuel tank 19 is
atomized with the atomizing air 46 and is burned. Accordingly, even
when the liquid fuel 24 is intermittently supplied from the liquid
fuel supply tube 24 to the liquid fuel tank 19, the liquid fuel
stored in the liquid fuel tank 19 is continuously discharged from
the liquid fuel discharge hole 22 of the liquid fuel tank 19. In
other words, even when the supply flow rate of the pump of the
liquid fuel supply system is reduced and the liquid fuel 24 is
intermittently supplied from the liquid fuel supply tube 25 to the
liquid fuel tank 19, the liquid level 23 of the liquid fuel 24
stored in the liquid fuel tank 19 fluctuates just a little up and
down and only causes the flow rate of the liquid fuel 24 discharged
from the liquid fuel discharge hole 22 to fluctuate a little. The
flow rate of supplied liquid fuel does not fluctuate as much as the
conventional one. It is therefore possible to stably supply the
liquid fuel 24 even if the flow rate of the liquid fuel supplied is
low, thus facilitating achievement of stable combustion and
eliminating the possibility of producing unburned exhausted gas and
causing accidental fire.
[0145] According to the two-fluid spray burner 11 of Embodiment 1,
the two-fluid spray burner 11 is configured so that the liquid fuel
22 discharged from the liquid fuel discharge hole 22 and flown into
the two-fluid converging space portion 43 converges with the
atomizing air flowing down the atomizing air passage 28 and flown
through the grooves 40 at the atomizing air introduction portion 37
to be introduced into the two-fluid converging space portion 43 and
then sprayed from the spray hole 44 together with the atomizing
air. Accordingly, the liquid fuel 24 is well mixed with the
atomizing air 46 with the flow speed increased at the grooves 40
(with the horizontal speed component increased) at the two-fluid
converging space portion 43 and then sprayed from the spray hole 44
of the two-fluid spray nozzle 38. Compared to the case of not
providing the two-fluid converging space portion 43 and grooves 40,
therefore, the spread angle of the liquid fuel 24 is larger, and
the liquid fuel 24 is surely atomized, so that the combustion
quality is improved.
[0146] According to the two-fluid spray burner 11 of Embodiment 1,
the grooves 40 of the atomizing air introduction portion 37 are
formed along the tangent directions of the circumference of the
two-fluid converging space portion 43 in a top view. Accordingly,
the atomizing air 46 is swirled and mixed with the liquid fuel 24
at the two-fluid converging space portion 43. The liquid fuel 24
and atomizing air 46 are therefore mixed more surely. The liquid
fuel 24 sprayed from the spray hole 44 of the two-fluid spray
nozzle 38 can be therefore more surely atomized, and the combustion
quality of the liquid fuel 24 can be further improved.
[0147] According to the two-fluid spray burner 11 of Embodiment 1,
the plurality of grooves 40 of the atomizing air introduction
portion 37 are formed at positions rotationally symmetric around
the central axis of the two-fluid converging space portion 43.
Accordingly, the circumferential distribution of the liquid fuel 24
sprayed from the spray hole 44 of the two-fluid spray nozzle 38 can
be equalized, and thus improving the combustion characteristics of
the liquid fuel 24.
[0148] Moreover, the two-fluid spray burner 11 of Embodiment 1 is
provided with the coil spring 36 pressing the liquid fuel tank 19
downward. The bottom portion 21 of the liquid fuel tank 19 is
therefore pressed against the atomizing air introduction portion 37
of the two-fluid spray nozzle 38 to be brought into firm contact.
Accordingly, the undersurface 21b of the bottom portion 21 of the
fuel tank 19 and the top surface 37a of the atomizing air
introduction portion 37 are firmly in contact to each other to
prevent gap between these contact surfaces 21b and 37a. It is
therefore possible to prevent the atomizing air 46 from flowing
into portion other than the grooves 40 and allow the effect of wide
spray by the grooves 40 to be sufficiently exerted.
[0149] Moreover, according to the two-fluid spray burner 11 of
Embodiment 1, the two-fluid converging space portion 43 is reversed
conical, and the spray hole 44 is formed at the vertex position of
the reverse conical space 43. Accordingly, the liquid fuel 24 and
atomizing air 46 can be surely mixed at the two-fluid converging
space portion 43. The liquid fuel 24 to be sprayed from the spray
hole 44 is more surely atomized, thus further improving the
combustion characteristics of the liquid fuel 24.
[0150] Moreover, according to the two-fluid spray burner 11 of
Embodiment 1, the two-fluid spray burner 11 is configured so that
the cylindrical gas fuel passage 14 is formed between the sprayer
outer cylinder 27 and the gas fuel supply tube 47 surrounding the
sprayer outer cylinder 27 and allows the gas fuel 49 to flow down
the gas fuel passage 14 to be sprayed from the lower end of the gas
fuel passage 14 and burned. Accordingly, the gas fuel 49 sprayed
from the cylindrical gas fuel passage 14 is circumferentially
uniform. It is therefore possible to improve the combustion
characteristics, thus achieving a flame holding effect by the gas
fuel 49 when the liquid fuel 24 is supplied at a low flow rate, for
example.
[0151] Moreover, in the two-fluid spray burner 11 of Embodiment 1,
in the case where the end portion 25A of the liquid fuel supply
tube 25 is in contact with the internal peripheral surface 20a of
the side potion 20 of the liquid fuel tank 19, the liquid fuel 24
flows down the internal peripheral surface 20a even when the flow
rate of the liquid fuel 24 discharged from the liquid fuel supply
tube 25 is low. It is therefore possible to achieve more stable
discharge of the liquid fuel 24 from the liquid fuel discharge hole
22. In other words, when the liquid fuel 24 falls in droplets, the
liquid level 23 of the liquid fuel 24 stored in the liquid fuel
tank 19 greatly fluctuates. In the case where the liquid level 23
is very low, it can be thought that the liquid fuel discharge hole
22 is temporarily exposed and discharge of the liquid fuel 24 is
stopped. However, allowing the liquid fuel 24 to flow down along
the inner peripheral surface 20a of the liquid fuel tank 19 can
prevent occurrence of such a disadvantage.
[0152] Furthermore, according to the two-fluid spray burner 11 of
Embodiment 1, the two-fluid spray burner 11 is configured so that
after flowing down the combustion air passage 15, the combustion
air 50 is blocked by the plate 18 and is introduced to the outer
peripheral side of the plate 18, away from the two-fluid spray
nozzle 38, to flow through the combustion air hole 52 into the
combustion space 13. Accordingly, only a part of the combustion air
50 is mixed with the liquid fuel 24 sprayed from the two-fluid
spray nozzle 38 at the combustion space 13 and used in combustion
of the liquid fuel 24, and the residual of the combustion air 50
further flows down and is mixed with the combustion exhausted gas
produced by the combustion. It is therefore possible to achieve
proper mixture of the combustion air 50 and liquid fuel 24 through
one supply of the combustion air (one step) and produce a large
amount of combustion exhaust gas without exceedingly cooling flame.
In other words, it is possible to achieve a burner such as a
two-fluid spray burner which is capable of producing a large amount
of combustion exhaust gas with a simple configuration and does not
cause generation of unburned gas and accidental fire.
[0153] Moreover, the combustion air 50 is caused by the plate 18 to
flow into the combustion space 13 at the position away from the
two-fluid spray nozzle 38. Accordingly, the position where a part
of the combustion air 50 is supplied to fuel can be set downward
away from the plate 18. The position of flame is therefore downward
away from the plate 18, thus preventing adherence of soot to the
undersurface of the plate 18. Although a lot of soot adhering to
the undersurface of the plate 18 may cause disadvantages such as
clogging of the two-fluid spray nozzle 38 due to the soot and
abnormal heating of the two-fluid sprayer 12 due to the soot
absorbing radiation heat from flame, by preventing soot from
sticking to the undersurface of the plate 18 as described above,
such disadvantages can be prevented from occurring.
[0154] Moreover, according to the two-fluid spray burner 11 of
Embodiment 1, the two-fluid spray burner 11 is configured so that
the first cylinder 16 extending downward from the undersurface of
the plate 18 for delaying supply of the combustion air is provided,
and the cylindrical combustion air passage 53 communicating with
the combustion air hole 52 is formed between the first cylinder 16
and the burner outer cylinder 48. The combustion air 50 passing
through the combustion air hole 52 is thus allowed to flow down the
combustion air passage 53 and then flow into the combustion space
13 from the lower end of the combustion air passage 53. It is
therefore possible to delay supply of a part of the combustion air
50 to the liquid fuel 24 sprayed from the two-fluid spray nozzle
38. In other words, the position where a part of the combustion air
50 is supplied to the liquid fuel 24 can be set downward away from
the plate 18. Accordingly, the position of flame is set downward
away from the plate 18, thus preventing soot from sticking to the
undersurface of the plate 18.
[0155] It is possible to obtain the operational effect of setting
the position where the part of the combustion air 50 is supplied to
the liquid fuel 24 downward away from the plate 18 by provision of
only the plate 18 as described above. However, as described in
Embodiment 1, by providing the first cylinder 16 for delaying
supply of the combustion air, the position where a part of the
combustion air 50 is supplied to the liquid fuel 24 can be more
surely set downward away from the plate 18.
[0156] Moreover, when the plate 18 cannot be made large so much
because of limitation on size of the two-fluid spray burner 11 and
the like, and the distance between the two-fluid spray nozzle 38
and combustion air hole 52 cannot be made long enough, the part of
the combustion air 50 supplied to the liquid fuel 24 becomes
excessive, and the flame may be excessively cooled. On the
contrary, by providing the first cylinder 16 for delaying supply of
combustion air as shown in Embodiment 1, not only the position
where the part of the combustion air 50 is supplied to the liquid
fuel 24 can be set downward away from the plate 18, but also the
amount of the part of the combustion air 50 supplied to the liquid
fuel 24 can be reduced to a proper amount. Accordingly, in such a
view, provision of the first cylinder 16 like Embodiment 1 is
effective. By providing the first cylinder 16, the plate 18 can be
reduced in size, and the two-fluid spray burner 11 can be
miniaturized.
[0157] Moreover, according to the two-fluid spray burner 11 of
Embodiment 1, the second cylinder 17 extending from the
undersurface of the plate 18 for preventing stagnation is provided
within the first cylinder 16 for delaying supply of combustion air.
Accordingly, stagnation (convection) of the liquid fuel 24 can be
prevented from occurring near the undersurface of the plate 18 by
the second cylinder 17 for preventing stagnation. It is therefore
possible to prevent the liquid fuel 24 stagnating near the
undersurface of the plate 18 from catching fire and soot from
sticking to the undersurface of the plate 18.
[0158] Moreover, according to the two-fluid spray burner 11 of
Embodiment 1, by surrounding flame with the burner outer cylinder
48, flame (the sprayed liquid fuel 24) and the combustion air 50
can be well mixed in the combustion space 13, thus improving the
combustion characteristics.
Embodiment 2
[0159] FIG. 6(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 2 of present invention, and FIG.
6(b) is a top view showing a two-fluid spray nozzle provided for
the two-fluid sprayer (a view in a direction of arrows E of FIG.
6(a)).
[0160] As shown in FIGS. 6(a) and 6(b), in a two-fluid spray nozzle
38 of a two-fluid sprayer 12 in Embodiment 2, grooves (slits) 61
are formed at four places in the circumference of the atomizing air
introduction portion 37. These grooves 61 are collision type. The
grooves 61 are individually extended in radial directions of the
two-fluid converging space portion 43 having a circular top view
and are formed at positions rotationally symmetric
(circumferentially at equal intervals) around the central axis of
the two-fluid converging space portion 43 (the central axis of the
spray hole 44 in the example of the drawing).
[0161] In the two-fluid sprayer 21, after flowing down the
atomizing air passage 28, the atomizing air 46 flows through the
grooves 61 of the atomizing air introduction portion 37 in the
two-fluid spray nozzle 38 to increase in flow speed and is
introduced into the two-fluid converging space portion 43. The
atomizing air 46 collides and converges (is mixed) with the liquid
fuel 24 discharged from the liquid fuel discharge hole 22 of the
liquid fuel tank 19 at the two-fluid converging space portion 43.
The liquid fuel 24 and atomizing air 46 are thus well mixed, and
the liquid fuel 24 is atomized with the atomizing air 46 and then
sprayed from the spray hole 44 of the two-fluid spray nozzle 38
together with the atomizing air 46 into the combustion space
13.
[0162] The configuration of the other parts of the two-fluid
sprayer 12 of FIG. 6 is the same as that of the two-fluid sprayer
12 of FIG. 4. The configuration of the parts other than the
two-fluid sprayer of the two-fluid spray burner of Embodiment 2 is
the same as that of the two-fluid spray burner 11 of FIGS. 1 to
3.
[0163] According to the two-fluid spray burner of Embodiment 2, the
following operational effects can be obtained, and in addition, the
same operational effects as those of the aforementioned Embodiment
1 can be obtained.
[0164] Specifically, according to the two-fluid spray burner of
Embodiment 2, by forming the grooves 61 of the atomizing gas
introduction portion 37 along the radial directions of the
two-fluid converging space portion 43 in the top view, the
atomizing air 46 collides with the liquid fuel 24 at the two-fluid
converging space portion 43 to be mixed with the liquid fuel 24.
Accordingly, the liquid fuel 24 and atomizing air 46 are more
surely mixed. The liquid fuel 24 sprayed from the spray hole 44 of
the two-fluid spray nozzle 38 can be atomized more surely, thus
further improving the combustion characteristics of the liquid fuel
24.
[0165] Furthermore, the plurality of grooves 61 of the atomizing
gas introduction portion 37 are formed at positions rotationally
symmetric around the central axis of the two-fluid converging space
portion 43. Accordingly, the distribution of the liquid fuel 24
sprayed from the spray hole 44 of the two-fluid spray nozzle 38 can
be uniformed in the circumferential direction, thus improving the
combustion characteristics of the liquid fuel 24.
Embodiment 3
[0166] FIG. 7 (a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 3 of present invention, and FIG.
7(b) is a top view showing a two-fluid spray nozzle provided for
the two-fluid sprayer (a view in a direction of an arrow F of FIG.
7(a))
[0167] As shown in FIG. 7, in the two-fluid sprayer 12 in
Embodiment 3, the inner surface (top surface) 21a of the bottom
portion 21 of the liquid fuel tank 19 is a tapered (reverse
conical) surface, and the fine liquid fuel discharge hole 22 is
formed at the center (at the vertex position of the reverse conical
tapered surface). In the outer surface (undersurface) 21b of the
bottom portion 21 of the liquid fuel tank 19, an outside portion
21b-1 composed of a tapered (reverse truncated conical) surface,
and an inside portion 21b-2 is composed of a circular horizontal
surface.
[0168] On the other hand, the atomizing air introduction portion 37
of the two-fluid spray nozzle 38 is formed in a ring-shape, and an
inner peripheral surface 37b thereof is composed of a tapered
(reverse truncated cone-shaped) surface. The liquid fuel tank 19 is
installed on the atomizing air introduction portion 37 with the
outside portion 21b-1 (tapered surface portion) of the undersurface
21b of the bottom portion 21 being abutted and fitted into the
inner peripheral surface 37b (tapered surface portion) of the
atomizing air introduction portion 37. In this case, the liquid
fuel tank 19 is pressed downward by the coil spring 36 (see FIG.
4), and the outside portion 21b-1 (tapered surface portion) of the
undersurface 21b of the bottom portion 21 of the liquid fuel tank
19 is therefore pressed against the inner peripheral surface 37b
(tapered surface portion) of the atomizing air introduction portion
37 for a tight close contact, thus preventing gap between these
contact surfaces 21b-1 and 37b.
[0169] The nozzle body 39 of the two-fluid spray nozzle 38 includes
a reverse conical space (recess) 42 formed in the central part, and
the fine spray hole 44 is formed at the center (at the vertex
position of the reverse conical space 42). The space 41 of the
atomizing air introduction portion 37 and the space 42 of the
nozzle body 39 are continuous to each other and constitute the
two-fluid converging space portion 43. In other words, the
two-fluid converging space portion 43 has a circular plan view (top
view) and has a tapered structure with the diameter thereof
gradually reduced towards the spray hole 44. In the atomizing air
introduction portion 37, the grooves (slits) 40 are formed at two
places in the circumference thereof. These grooves 40 are swirling
type like the grooves 40 of FIG. 5 and are extended in tangent
directions of the circumference of the two-fluid converging space
portion 43 in a top view. Moreover, the grooves 40 are formed at
positions rotationally symmetric around a central axis of the
two-fluid converging space portion 43 (circumferentially at equal
intervals). The grooves formed at the atomizing air introduction
portion 37 are not limited to the swirling type but may be
collision type like that of FIG. 6.
[0170] The configuration of the other parts of the two-fluid
sprayer 12 of FIG. 7 is the same in that of the two-fluid sprayer
12 of FIG. 4. The configuration of the parts other than the
two-fluid sprayer of the other part of the two-fluid spray burner
of Embodiment 3 is the same as that of the two-fluid spray burner
11 of FIGS. 1 to 3.
[0171] According to the two-fluid spray burner of Embodiment 3, the
following operational effects can be obtained, and in addition, the
same operational effects as those of the aforementioned Embodiments
1 and 2 can be obtained.
[0172] Specifically, according to the two-fluid spray burner of
Embodiment 3, the liquid fuel tank 19 is installed on the atomizing
gas introduction portion 37 with the tapered surface portion (the
outside portion 21b-1 of the undersurface 21b of the bottom portion
21) of the liquid fuel tank 19 being abutted and fitted to the
tapered surface portion (inner peripheral surface 37b) of the
atomizing gas introduction portion 37. It is therefore easy to
align the central axes of the liquid fuel tank 19 and two-fluid
spray nozzle 38. Accordingly, the liquid fuel tank 19 is installed
at the center. The width of the atomizing air passage 28 can be
therefore made uniform in circumferential direction, so that the
flow of the atomizing air 46 in the atomizing air passage 28 can be
made uniform in the circumferential direction. This makes it
possible to hold the symmetric properties of the liquid fuel 24 (or
symmetric properties of the flame) sprayed from the spray hole 44
of the two-fluid spray nozzle 38.
[0173] Moreover, according to the two-fluid spray burner of
Embodiment 3, by pressing the liquid fuel tank 19 downward by the
coil spring 36 (see FIG. 4), the bottom portion 21 of the liquid
fuel tank 19 is pressed against the atomizing air introduction
portion 37 of the two-fluid spray nozzle 38 to bring the tapered
surface portion (outside portion 21b-1) of the bottom portion 21 of
the fuel tank 19 and the tapered surface portion (inner peripheral
surface 37b) of the atomizing air introduction portion 37 into firm
contact, thus preventing gap between these contact surfaces 21b-1
and 37b. It is therefore possible to prevent the atomizing air 46
from flowing into portions other than the grooves 40, thus allowing
the effect of the wide spray by the grooves 40 to be sufficiently
exerted.
Embodiment 4
[0174] FIG. 8(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 4 of the present invention (a
longitudinal sectional view taken along a line G-G of FIG. 8(b));
FIG. 8(b) is a bottom view showing a liquid fuel tank provided for
the two-fluid sprayer (a view in a direction of an arrow H of FIG.
8(a)); FIG. 8(c) is a view in a direction of an arrow I of FIG.
8(b); and FIG. 8(d) is a transverse sectional view taken along a
line J-J of FIG. 8(a).
[0175] As shown in FIG. 8, in the two-fluid sprayer 12 of
Embodiment 4, the inner surface (top surface) 21a of the bottom
portion 21 of the liquid fuel tank 19 is composed of a tapered
(reverse conical) surface, and the fine liquid fuel discharge hole
22 is formed at the center (at the vertex position of the reverse
conical tapered surface). Moreover, in the outer surface
(undersurface) 21b of the bottom portion 21 of the liquid fuel tank
19, the outside portion 21b-1 is composed of a tapered (reverse
truncated cone-shaped) surface, and an inside portion 21b-2 is
composed of a circular horizontal surface.
[0176] On the other hand, the two-fluid spray nozzle 38 does not
include an atomizing air introduction portion (see FIG. 7) and is
integrally formed with the sprayer outer cylinder 27 at the lower
end of the sprayer outer cylinder 27 (a separate body may be fixed
by welding or the like). The two-fluid spray nozzle 38 has the
inner surface (top surface) 38a which is composed of a tapered
(reverse conical) surface. The liquid fuel tank 19 is installed on
the two-fluid spray nozzle 38 with the outside portion 21b-1
(tapered surface portion) of the undersurface 21b of the bottom
portion 21 being abutted and fitted to the inner surface 38a
(tapered surface portion) of the two-fluid spray nozzle 38. In this
case, the liquid fuel tank 19 is pressed downward by the coil
spring 36 (see FIG. 4), so that the outside portion 21b-1 (tapered
surface portion) of the undersurface 21b of the bottom portion 21
of the liquid fuel tank 19 is pressed against the inner surface 38a
(tapered surface portion) of the two-fluid spray nozzle 38 to be
brought into firm contact, thus preventing gap between these
contact surfaces 21b-1 and 38b.
[0177] A reverse conical space formed by the inner surface 38a of
the tapered structure in the central part of the two-fluid spray
nozzle 38 serves as the two-fluid converging space portion 43. The
fine spray hole 44 is formed at the center (the vertex position of
a reverse conical space 43) of the two-fluid converging space
portion 43 and communicates with the two-fluid converging space
portion 43. Specifically, the two-fluid converging space portion 43
has a circular plan view (top view) and has a tapered structure
with the diameter thereof gradually reduced towards the spray hole
44.
[0178] In the undersurface 21b side of the bottom portion 21 of the
liquid fuel tank 19, grooves (slits) 71 are formed at two places in
the circumference thereof. These grooves 71 are swirling type and
are extended in tangent directions of the circumference of the
two-fluid converging space portion 43 in a top view. Moreover, the
grooves 71 are formed at positions rotationally symmetric around a
central axis of the two-fluid converging space portion 43
(circumferentially at equal intervals).
[0179] Accordingly, after flowing down the atomizing air passage
28, the atomizing air 46 flows through the grooves 71 of the bottom
portion 21 of the liquid fuel tank 19 to increase in flow rate and
is then introduced to the two-fluid converging space portion 43.
The atomizing air 46 becomes swirling flow in the two-fluid
converging space portion 43 and converges (is mixed) with the
liquid fuel 24 discharged from the liquid fuel discharge hole 22 of
the liquid fuel tank 19. The liquid fuel 24 and atomizing air 46
are thus well mixed, and the liquid fuel 24 is atomized with the
atomizing air 46 and sprayed from the spray hole 44 of the
two-fluid spray nozzle 38 into a combustion space 13.
[0180] The configuration of the other parts of the two-fluid
sprayer 12 of FIG. 8 is the same as that of the two-fluid sprayer
12 of FIG. 4. The configuration of the parts other than the
two-fluid sprayer of the two-fluid spray burner of Embodiment 3 is
the same as that of the two-fluid spray burner 11 of FIGS. 1 to
3.
[0181] According to the two-fluid spray burner of Embodiment 3, the
following operational effects can be obtained, and in addition, the
same operational effects as those of the aforementioned Embodiment
1 can be obtained.
[0182] According to the two-fluid spray burner of Embodiment 4, the
two-fluid spray burner is configured so that the liquid fuel 24
which is discharged from the liquid fuel discharge hole 44 and
flows into the two-fluid converging space portion 43 converges at
the two-fluid converging space portion 43 with the atomizing air 46
flowing down the atomizing air passage 28 and then flowing through
the grooves 71 at the bottom portion 21 of the liquid fuel tank 19
to be introduced into the two-fluid converging space portion 43 and
then is sprayed from the spray hole 44 together with the atomizing
air 46. Accordingly, the liquid fuel 24 is well mixed with the
atomizing air 46 whose the flow rate is increased through the
grooves 71 (with the horizontal speed component increased) at the
two-fluid converging space portion 43 and then sprayed from the
spray hole 44. Accordingly, compared to the case of not providing
the two-fluid converging space portion 43 and grooves 71, the
spread angle of the sprayed liquid fuel 24 is larger, and the
liquid fuel 24 is surely atomized, thus improving the combustion
characteristics of the liquid fuel 24.
[0183] Furthermore, the liquid fuel tank 19 is installed on the
two-fluid spray nozzle 38 with the tapered surface portion (the
outside portion 21b-1 of the undersurface 21b of the bottom portion
21) of the liquid fuel tank 19 abutted and fitted to the tapered
surface portion (inner surface 38a) of the two-fluid spray nozzle
38. Thus, it is easy to align the central axes of the liquid fuel
tank 19 and two-fluid spray nozzle 38. Accordingly, the liquid fuel
tank 19 is installed at the center. The width of the atomizing air
passage 28 can be therefore made uniform in circumferential
direction, so that the flow of the atomizing air 46 in the
atomizing air passage 28 can be made uniform in the circumferential
direction. It is therefore possible to secure the symmetric
properties of the liquid fuel 24 (or symmetric properties of flame)
sprayed from the spray hole 44 of the two-fluid spray nozzle
38.
[0184] Moreover, the grooves 71 of the bottom portion 21 of the
liquid fuel tank 19 are formed along the tangent directions of the
circumference of the two-fluid converging space portion 43 in a top
view. Accordingly, the atomizing air 46 is swirled and mixed with
the liquid fuel 24 at the two-fluid converging space portion 43.
The liquid fuel 24 and atomizing air 46 are thus mixed more surely.
The liquid fuel 24 sprayed from the spray hole 44 of the two-fluid
spray nozzle 38 can be therefore surely atomized, thus improving
the combustion characteristics of the liquid fuel 24.
[0185] Moreover, the plurality of grooves 71 of the bottom portion
21 of the liquid fuel tank 19 are formed at positions rotationally
symmetric around the central axis of the two-fluid converging space
portion 43. Accordingly, the liquid fuel 24 sprayed from the spray
hole 44 of the two-fluid spray nozzle 38 is uniformly distributed
in the circumferential direction, thus improving the combustion
characteristics of the liquid fuel 24.
[0186] According to the two-fluid spray burner of Embodiment 4, by
pressing the liquid fuel tank 19 downward by the coil spring 36
(see FIG. 4), the bottom portion 21 of the liquid fuel tank 19 is
pressed against the two-fluid spray nozzle 38, so that the tapered
surface portion (outside portion 21b-1) of the bottom portion 21 of
the fuel tank 19 and the tapered surface portion (inner surface
38a) of the two-fluid spray nozzle 38 are brought into firm
contact, thus preventing gap between these contact surfaces 21b-1
and 38a. It is therefore possible to prevent the atomizing air 46
from flowing into portions other than the grooves 71, thus allowing
the effect of the wide spray by the grooves 71 to be sufficiently
exerted.
Embodiment 5
[0187] FIG. 9(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 5 (a longitudinal sectional view
taken along a line K-K of FIG. 9(b)); FIG. 9(b) is a bottom view
showing a liquid fuel tank provided for the two-fluid sprayer (a
view in a direction of an arrow L of FIG. 9(a)); and FIG. 9 (c) is
a transverse sectional view taken along a line M-M of FIG.
9(a).
[0188] As shown in FIG. 9, in the two-fluid sprayer 12 of
Embodiment 5, the inner surface (top surface) 21a of the bottom
portion 21 of the liquid fuel tank 19 is composed of a tapered
(reverse conical) surface, and the fine liquid fuel discharge hole
22 is formed at the center (at the vertex position of the reverse
conical tapered surface). Moreover, in the outer surface
(undersurface) 21b of the bottom portion 21 of the liquid fuel tank
19, the outside portion 21b-1 is composed of a tapered (reverse
truncated cone-shaped) surface, and an inside portion 21b-2 is
composed of a circular horizontal surface.
[0189] On the other hand, the two-fluid spray nozzle 38 does not
include an atomizing air introduction portion (see FIG. 7) and is
integrally formed with the sprayer outer cylinder 27 at the lower
end of the sprayer outer cylinder 27 (a separate body may be fixed
by welding or the like). The two-fluid spray nozzle 38 has the
inner surface (top surface) 38a which is composed of a tapered
(reverse conical) surface. The liquid fuel tank 19 is installed on
the two-fluid spray nozzle 38 with the outside portion 21b-1
(tapered surface portion) of the undersurface 21b of the bottom
portion 21 abutted and fitted to the inner surface 38a (tapered
surface portion) of the two-fluid spray nozzle 38. In this case,
the liquid fuel tank 19 is pressed downward by the coil spring 36
(see FIG. 4), so that the outside portion 21b-1 (tapered surface
portion) of the undersurface 21b of the bottom portion 21 of the
liquid fuel tank 19 is pressed against the inner surface 38a
(tapered surface portion) of the two-fluid spray nozzle 38 and
brought into firm contact, thus preventing gap between these
contact surfaces 21b-1 and 38b.
[0190] A reverse conical space formed by the inner surface 38a with
the tapered structure in the central part of the two-fluid spray
nozzle 38 serves as the two-fluid converging space portion 43. The
fine spray hole 44 is formed at the center (the vertex position of
the reverse conical space 43) of the two-fluid converging space
portion 43 and communicates with the two-fluid converging space
portion 43. Specifically, the two-fluid converging space portion 43
has a circular plan view (top view) and has a tapered structure
with the diameter thereof gradually reduced towards the spray hole
44.
[0191] In the undersurface 21b side of the bottom portion 21 of the
liquid fuel tank 19, grooves (slits) 81 are formed at four places
in the circumference thereof. These grooves 81 are the collision
type and are extended in radial directions of the two-fluid
converging space portion 43 in a top view and are formed at
positions rotationally symmetric around the central axis of the
two-fluid converging space portion 43 (circumferentially at equal
intervals).
[0192] After flowing down the atomizing air passage 28, the
atomizing air 46 flows through the grooves 81 at the bottom portion
21 of the liquid fuel tank 19 to increase in flow speed and then
introduced to the two-fluid converging space portion 43. The
atomizing air 46 collides and converges (is mixed) with the liquid
fuel 24 discharged from the liquid fuel discharge hole 22 of the
liquid fuel tank 19 at the two-fluid converging space portion 43.
The liquid fuel 24 and atomizing air 46 are thus well mixed, and
the liquid fuel 24 is atomized with the atomizing air 46 and then
sprayed from the spray hole 44 of the two-fluid spray nozzle 38
together with the atomizing air 46 into the combustion space
13.
[0193] The configuration of the other parts of the two-fluid
sprayer 12 of FIG. 9 is the same as that of the two-fluid sprayer
12 of FIG. 4. The configuration of the parts other than the
two-fluid sprayer of the two-fluid spray burner of Embodiment 5 is
the same as that of the two-fluid spray burner 11 of FIGS. 1 to
3.
[0194] According to the two-fluid spray burner of Embodiment 5, the
same operational effects as those of the aforementioned Embodiment
4 can be obtained, and in addition, the same operational effects as
those of the aforementioned Embodiment 1 can be obtained.
[0195] According to the two-fluid spray burner of Embodiment 5, the
two-fluid spray burner is configured so that the liquid fuel 24
which is discharged from the liquid fuel discharge hole 44 and
flows into the two-fluid converging space portion 43 converges at
the two-fluid converging space portion 43 with the atomizing air 46
which flows down the atomizing air passage 28 and then flows
through the grooves 81 at the bottom portion 21 of the liquid fuel
tank 19 and then is introduced into the two-fluid converging space
portion 43 to be sprayed from the spray hole 44 together with the
atomizing air 46. The liquid fuel 24 is therefore well mixed with
the atomizing air 46 with the flow rate increased through the
grooves 81 (with the horizontal speed component increased) at the
two-fluid converging space portion 43 and then sprayed from the
spray hole 44. Compared to the case of not providing the two-fluid
converging space portion 43 and grooves 81, the spread angle of the
sprayed liquid fuel 24 is larger, and the liquid fuel 24 is surely
atomized, thus improving the combustion characteristics of the
liquid fuel 24.
[0196] Furthermore, the liquid fuel tank 19 is installed on the
two-fluid spray nozzle 38 with the tapered surface portion (the
outside portion 21b-1 of the undersurface 21b of the bottom portion
21) of the liquid fuel tank 19 abutted and fitted in the tapered
surface portion (inner surface 38a) of the two-fluid spray nozzle
38, and it is therefore easy to align the central axes of the
liquid fuel tank 19 and two-fluid spray nozzle 38. Accordingly, the
liquid fuel tank 19 is installed at the center. The width of the
atomizing air passage 28 can be therefore made uniform in
circumferential direction, so that the flow of the atomizing air 46
in the atomizing air passage 28 can be made uniform in the
circumferential direction. It is therefore possible to secure the
symmetric properties of the liquid fuel 24 (or symmetric properties
of flame) sprayed from the spray hole 44 of the two-fluid spray
nozzle 38.
[0197] Moreover, the grooves 81 of the bottom portion 21 of the
liquid fuel tank 19 are formed along tangent directions of the
circumference of the two-fluid converging space portion 43 in a top
view. Accordingly, the atomizing air 46 is swirled and mixed with
the liquid fuel 24 at the two-fluid converging space portion 43,
and the liquid fuel 24 and atomizing air 46 are thus mixed more
surely. The liquid fuel 24 sprayed from the spray hole 44 of the
two-fluid spray nozzle 38 can be therefore surely atomized, thus
improving the combustion characteristics of the liquid fuel 24.
[0198] Moreover, the plurality of grooves 81 of the bottom portion
21 of the liquid fuel tank 19 are formed at positions rotationally
symmetric around the central axis of the two-fluid converging space
portion 43. Accordingly, the liquid fuel 24 sprayed from the spray
hole 44 of the two-fluid spray nozzle 38 can be uniformly
distributed in the circumferential direction, thus improving the
combustion characteristics of the liquid fuel 24.
[0199] In the two-fluid spray burner of Embodiment 4, by pressing
the liquid fuel tank 19 downward by the coil spring 36 (see FIG.
4), the bottom portion 21 of the liquid fuel tank 19 is pressed
against the two-fluid spray nozzle 38 to bring the tapered surface
portion (outside portion 21b-1) of the bottom portion 21 of the
fuel tank 19 and the tapered surface portion (inner surface 38a) of
the two-fluid spray nozzle 38 into firm contact, thus preventing
gap between these contact surfaces 21b-1 and 38a. It is therefore
possible to prevent the atomizing air 46 from flowing into portions
other than the grooves 81, thus allowing the effect of the wide
spray by the grooves 81 to be sufficiently exerted.
Embodiment 6
[0200] FIG. 10(a) is a longitudinal sectional view showing a
structure of lower part of a two-fluid sprayer in a two-fluid spray
burner according to Embodiment 6; and FIG. 10(b) is a transverse
sectional view taken along a line L-L of FIG. 10(a).
[0201] As shown in FIG. 10, in the two-fluid sprayer 12 of
Embodiment 6, the inner surface (top surface) 21a of the bottom
portion 21 of the liquid fuel tank 19 is composed of a tapered
(reverse conical) surface, and the fine liquid fuel discharge hole
22 is formed at the center (at the vertex position of the reverse
conical tapered surface). The outer surface (undersurface) 21b of
the bottom portion 21 of the liquid fuel tank 19 is composed of a
tapered (reverse truncated cone-shaped) surface. On the other hand,
the two-fluid spray nozzle 38 does not include an atomizing air
introduction portion (see FIG. 7) and is integrally formed with the
sprayer outer cylinder 27 at the lower end of the sprayer outer
cylinder 27 (a separate body may be fixed by welding or the like).
In the two-fluid spray nozzle 38, the inner surface (top surface)
38a is composed of a tapered (reverse conical) surface.
[0202] In the lower end portion of the outer peripheral surface 20b
of the side portion 20 of the liquid fuel tank 19, a plurality of
supporting portions 91 are provided in a protruding manner (four in
the example of the drawing). These supporting portions 91 are
provided at equal intervals in the circumferential direction of the
side portion 20. Outside portions 91a-1 of undersurfaces 91a are
individually composed of tapered surfaces which are sloped inward
along the inner surface 38a of the two-fluid spray nozzle 38. The
liquid fuel tank 19 is therefore supported with the outside
portions 91a-1 of the undersurfaces 91a of the supporting portions
91 abutted and fitted to the inner surface 38a of the two-fluid
spray nozzle 38. Accordingly, the tapered (reverse truncated
cone-shaped) gaps are secured between the outer surface 21a of the
bottom portion 21 of the liquid fuel tank 19 and the inner surface
38a of the two-fluid spray nozzle 38 and serve as atomizing air
passages 92. In other words, the first atomizing air passage 28
outside and the two-fluid converging space portion 43 inside
communicate with each other through the second atomizing air
passages 92.
[0203] The two-fluid converging space portion 43 is a reverse
conical space formed in the central part of the two-fluid spray
nozzle 38 by the inner surface 38a of a tapered structure. The fine
spray hole 44 is formed at the center of the two-fluid converging
space portion 43 (the vertex position of the reverse conical space
43) and communicates with the two-fluid converging space portion
43. Specifically, the two-fluid converging space portion 43 is
located under the liquid fuel discharge hole 22 and has a tapered
structure including a circular plan view (top view) with the
diameter thereof gradually reduced towards the spray hole 44.
[0204] After flowing down the atomizing air passage 28, the
atomizing air 46 passes through atomizing air passage portions 93
between the supporting portions 91 and flows through the atomizing
air passages 92 to be introduced to the two-fluid converging space
portion 43. The atomizing air 46 collides and converges (is mixed)
with the liquid fuel 24 discharged from the liquid fuel discharge
hole 22 of the liquid fuel tank 19 at the two-fluid converging
space portion 43. The liquid fuel 24 is atomized with the atomizing
air 46 and then sprayed from the spray hole 44 of the two-fluid
spray nozzle 38 together with the atomizing air 46 into the
combustion space 13.
[0205] The configuration of the other parts of the two-fluid
sprayer 12 of FIG. 10 is the same as that of the two-fluid sprayer
12 of FIG. 4. The configuration of the parts other than the
two-fluid sprayer of the two-fluid spray burner of Embodiment 6 is
the same as that of the two-fluid spray burner 11 of FIGS. 1 to
3.
[0206] According to the two-fluid spray burner of Embodiment 6, the
following operational effects can be obtained, and in addition, the
same operational effects as those of the aforementioned Embodiment
1 can be obtained.
[0207] Specifically, according to the two-fluid spray burner of
Embodiment 6, the liquid fuel 24 which is discharged from the
liquid fuel discharge hole 22 and flows into the two-fluid
converging space portion 43 converges at the two-fluid converging
space portion 43 with the atomizing air 46 which flows down the
first atomizing gas passage 28, through the atomizing air passage
portions 93 between the supporting portions 91, and through the
second atomizing air passage 92 to be introduced into the two-fluid
converging space portion 43 and is then sprayed from the spray hole
44 with the atomizing air 46. Accordingly, the liquid fuel 24 is
mixed with the atomizing air 46 at the two-fluid converging space
portion 43 and then sprayed from the spray hole 44 of the two-fluid
spray nozzle 38. Accordingly, compared to the case of not providing
the two-fluid converging space portion 43, the spread angle of the
sprayed liquid fuel 24 is larger, and the liquid fuel 24 is surely
atomized, thus improving the combustion characteristics of the
liquid fuel 24.
Embodiment 7
[0208] FIG. 11 is a longitudinal sectional view showing a structure
of a two-fluid spray burner according to Embodiment 7 of the
present invention; and FIG. 12 is a transverse sectional view taken
along a line M-M of FIG. 11.
[0209] As shown in FIGS. 11 and 12, in the two-fluid spray burner
of Embodiment 7, the plate 18 is a porous plate. Specifically, in
the ring-shaped plate 18, a plurality of combustion air holes 101
are formed. All of these combustion air holes 101 are provided
inside of the combustion air hole 52 (first cylinder 16).
Accordingly, after flowing down the combustion air passage 15, most
of the combustion air 50 passes through the combustion air hole 52
on the outer periphery of the plate 19, flows through the
combustion air passage 53 located outside of the first cylinder 16
and into the combustion space 13. Meanwhile, a part of the
combustion air 50 flows through the combustion air holes 101
located inside of the first cylinder 16 and into the combustion
space 13.
[0210] The configuration of the other parts of the two-fluid spray
burner 11 of FIGS. 11 and 12 is the same as that of the two-fluid
spray burner 11 of FIGS. 1 to 3.
[0211] According to the two-fluid spray burner of Embodiment 7, the
following operational effects can be obtained, and in addition, the
same operational effects as those of the aforementioned Embodiment
1 can be obtained.
[0212] Specifically, according to the two-fluid spray burner of
Embodiment 7, by forming the plurality of additional combustion air
holes 101 in the plate 18 position inside of the combustion air
hole 52, a part of the combustion air 50 flows through these
combustion air holes 101. Such a flow of the combustion air 50 can
suppress stagnation of the combustion air occurring near the
undersurface of the plate 18, thus reducing adherence of soot to
the plate 18. Moreover, the cool combustion air flows near the
two-fluid spray nozzle 38 through the other combustion air holes
101. It is therefore possible to obtain a cooling effect on the
two-fluid spray nozzle 38, with the combustion air, which tends to
be excessively heated by radiation heat from flame.
Embodiment 8
[0213] FIG. 13 is a system diagram schematically showing a fuel
cell power generation system according to Embodiment 8 of the
present invention. FIG. 13 shows an example of a case where the
two-fluid spray burner of any one of the aforementioned Embodiments
1 to 7 is used as a heat source for a reformer in the fuel cell
power generation system.
[0214] As shown in FIG. 13, a combustion furnace 112 is provided in
upper part of a reformer 111, and the two-fluid spray burner 11 of
any one of the aforementioned Embodiments 1 to 7 is inserted into
the combustion furnace 112 from above. The two-fluid spray burner
11 is connected to a liquid fuel supply system, an atomizing air
supply system, and a combustion air supply system which are not
shown. The details of the two-fluid spray burner 11 are described
above.
[0215] The reformer 111 is connected to an unillustrated raw
material supply system. The raw material supply system supplies, to
the reformer 111, water and reforming fuel which is raw material
for reforming such as methane gas or kerosene. In the reformer 111,
the reforming fuel is steam-reformed by using the large amount of
combustion exhaust gas produced by combustion at the two-fluid
spray burner 11, thus generating reforming gas (hydrogen rich
gas).
[0216] The reforming gas generated by the reformer 11 is supplied
to an anode side of a fuel cell 113 as fuel for power generation.
In the fuel cell 113, the reforming gas (hydrogen) supplied to the
anode side and air (oxygen) supplied to a cathode side are
electrochemically reacted for power generation. The residual
reforming gas not used in power generation at the fuel cell 113 is
returned to the two-fluid spray burner 11 and used as gas fuel for
burner combustion.
[0217] According to the fuel cell power generation system of
Embodiment 8, the heat source of the reformer 111 is any one of the
two-fluid spray burner 11 of the aforementioned Embodiments 1 to 7.
Accordingly, the two-fluid spray burner 11 exerting the excellent
effects as described above can provide, for the reformer 111, an
improvement in performance, reduction of the costs and the
like.
[0218] In the above description, the liquid fuel tank 19 includes
only one liquid fuel discharge hole 22, but is not limited to this.
The liquid fuel tank 19 may include a plurality of the liquid fuel
tank 22.
[0219] In the above description, the liquid fuel discharge hole is
provided in the bottom portion of the liquid fuel tank, but is not
limited to this. The liquid fuel discharge hole may be provided in
the side portion of the liquid fuel tank. Specifically, the liquid
fuel tank may be of any type if the liquid fuel tank includes a
cylindrical side portion and a bottom portion provided at the lower
end of the side portion and is configured to store the liquid fuel
supplied from the liquid fuel supply tube and discharge the stored
liquid fuel through the single or the plurality of liquid fuel
discharge holes which are opened below the liquid level of the
stored liquid fuel and which are located in the side or bottom
portion.
[0220] In the above description, the liquid fuel tank is provided
within the sprayer outer cylinder, but is not limited to this. For
example, it may be configured to provide the liquid fuel tank
outside of the sprayer outer cylinder and supply the liquid fuel
discharged from the liquid fuel discharge hole of the liquid fuel
tank, through a tube or the like, to the space where the liquid
fuel converges with the atomizing gas.
[0221] In the above description, the upper end of the liquid fuel
tank is opened to allow pressure of the atomizing air flown into
the atomizing air passage to act on the liquid level of the liquid
fuel stored in the liquid fuel tank, but is not limited to this. It
may be configured so that the upper end of the liquid fuel tank may
be opened to the atmosphere, for example. In other words, the
liquid fuel discharged from the liquid fuel supply tube is once
stored in the liquid fuel tank, and produce a liquid column head of
the liquid fuel by the pressure balance between the inside and
outside (two-fluid converging space portion) of the liquid fuel
tank. Thus, the stored liquid fuel is continuously discharged from
the liquid fuel discharge hole.
[0222] Moreover, in the above description, two swirling-type
grooves and four collision-type grooves are provided. But the
numbers of grooves are not limited to these and may be set proper
numbers. However, in order to secure a uniform spray of the
atomized liquid fuel in circumferential direction, it is desirable
that the number of grooves in swirling-type to be two or more and
collision-type grooves to be three or more.
[0223] As described above, the configuration (invention) of
providing the plate (shielding plate), first cylinder for delaying
supply of combustion air, second cylinder for preventing stagnation
and the like can be applied to not only the aforementioned
two-fluid spray burner which includes a two-fluid sprayer, as a
fuel spray, spraying liquid fuel and atomizing gas. It could also
be applied to a burner including a fuel spray spraying only liquid
fuel or a fuel spray spraying gas fuel.
[0224] Moreover, in the above description, the combustion air holes
are provided on the outer periphery of the plate (shielding plate)
by forming protrusions on the circumference of the plate (shielding
plate) but is not limited to this. The combustion air holes only
have to be provided on the outer periphery of the plate (shielding
plate) and may be provided on the outer periphery of the plate by
opening a hole in the periphery of the plate (shielding plate)
itself, for example.
[0225] In the above description, the plate (shielding plate) is a
horizontal plate but is not limited to this. The plate may be
inclined obliquely downward from the inside towards the outside.
For example, the plate 18 may be shaped in a truncated cone as
virtually indicated by a dashed-dotted line in FIG. 11. Such an
inclined plate can provide not only the function of keeping the
combustion air away from the fuel spray nozzle (two-fluid spray
nozzle 38) but also provide a function of delaying supply of
combustion air, which is similar to the function of the first
cylinder.
INDUSTRIAL AVAILABILITY
[0226] The present invention relates to a two-fluid spray burner
which burns liquid fuel atomized with atomizing gas and is usefully
applied to a two-fluid spray burner for a reformer of a fuel cell
power generation system which may be operated in a condition where
amount of liquid fuel supplied is small.
* * * * *