U.S. patent application number 16/638211 was filed with the patent office on 2020-11-19 for oxygen-enriched burner and method for heating using oxygen-enriched burner.
The applicant listed for this patent is TAIYO NIPPON SANSO CORPORATION. Invention is credited to Yoshiyuki HAGIHARA, Takeshi SAITO, Naoki SEINO, Masashi YAMAGUCHI, Yasuyuki YAMAMOTO.
Application Number | 20200363059 16/638211 |
Document ID | / |
Family ID | 1000005016075 |
Filed Date | 2020-11-19 |
United States Patent
Application |
20200363059 |
Kind Code |
A1 |
SAITO; Takeshi ; et
al. |
November 19, 2020 |
OXYGEN-ENRICHED BURNER AND METHOD FOR HEATING USING OXYGEN-ENRICHED
BURNER
Abstract
An object of the present invention is to provide an
oxygen-enriched burner which can change any oscillation period and
uniformly heat an object to be heated with an excellent heat
transfer efficiency when heating the object to be heated while
moving the flame with self-induced oscillation, and a method for
heating using an oxygen enriched burner, and the present invention
provides an oxygen-enriched burner including a center fluid
ejection outlet and a peripheral fluid ejection outlet provided
around the center fluid ejection outlet, a pair of openings are
provided at opposite positions on side walls of a fluid ejection
flow path of the center fluid ejection outlet, a pair of the
openings are communicated with each other by a communication
portion, an interval between a pair of side walls downstream of the
openings in the fluid ejection flow path is gradually expanded
toward the downstream side, and the communication portion includes
a first communication pipe and the second communication pipe each
having a first end connected to a pair of the openings, and at
least one communication element connected to second ends of the
first communication pipe and the second communication pipe and
communicating the first communication pipe and the second
communication pipe.
Inventors: |
SAITO; Takeshi; (Tokyo,
JP) ; YAMAMOTO; Yasuyuki; (Tokyo, JP) ;
YAMAGUCHI; Masashi; (Tokyo, JP) ; HAGIHARA;
Yoshiyuki; (Tokyo, JP) ; SEINO; Naoki; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TAIYO NIPPON SANSO CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
1000005016075 |
Appl. No.: |
16/638211 |
Filed: |
July 26, 2018 |
PCT Filed: |
July 26, 2018 |
PCT NO: |
PCT/JP2018/028072 |
371 Date: |
February 11, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23D 14/22 20130101;
F23L 2900/07005 20130101; F23L 3/00 20130101; C21B 11/00 20130101;
F23D 2200/00 20130101; F23L 7/007 20130101; F23D 14/58 20130101;
F23D 14/56 20130101; F23D 14/84 20130101 |
International
Class: |
F23D 14/84 20060101
F23D014/84; F23L 7/00 20060101 F23L007/00; F23D 14/58 20060101
F23D014/58; F23D 14/56 20060101 F23D014/56; F23L 3/00 20060101
F23L003/00; F23D 14/22 20060101 F23D014/22; C21B 11/00 20060101
C21B011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2017 |
JP |
2017-165631 |
Claims
1. An oxygen-enriched burner which is configured to eject an
oxygen-enriched air or a fuel gas from a plurality of fluid
ejection outlets provided at the tip surface and burns them,
wherein a plurality of the fluid ejection outlets include a center
fluid ejection outlet and a peripheral fluid ejection outlet, a
pair of openings are provided at opposite positions on side walls
of a fluid ejection flow path of the center fluid ejection outlet,
a pair of the openings are communicated with a communication
portion, an interval between a pair of the side walls downstream of
the opening in the fluid ejection flow path is gradually expanded
toward the downstream side, the peripheral fluid ejection outlet is
provided around the center fluid ejection outlet, the communication
portion includes a first communication pipe and a second
communication pipe each having a first end connected to a pair of
the openings, and at least one communication element connected to a
second end of the first communication pipe and the second
communication pipe and communicating the first communication pipe
and the second communication pipe.
2. The oxygen-enriched burner according to claim 1, wherein a
plurality of the communication elements are provided in parallel
between the first communication pipe and the second communication
pipe.
3. The oxygen-enriched burner according to claim 2, wherein at
least one of an inner diameter and a length of a plurality of the
communication elements is different.
4. The oxygen-enriched burner according to claim 1, wherein the
first communication pipe, the second communication pipe, and the
communication element are detachably connected.
5. The oxygen-enriched burner according to claim 1, wherein the
communication portion includes an on-off valve provided between the
first communication pipe and the communication element and between
the second communication pipe and the communication element.
6. A method for heating using an oxygen-enriched burner, wherein an
object to be heated is heated using the oxygen-enriched burner
according to claim 1 while causing the fluid ejected from the
center fluid ejection outlet to the self-induced oscillation in an
expansion direction of the fluid ejection flow path,
7. The method for heating using an oxygen-enriched burner according
to claim 6, wherein a period of the self-induced oscillation of the
fluid ejected from the center fluid ejection outlet is 30 seconds
or less.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an oxygen-enriched burner
and a method for heating using an oxygen-enriched burner.
DESCRIPTION OF RELATED ART
[0002] A ladle and a tundish, which are furnaces (containers) that
receive pig iron (molten metal) used in iron producing process, are
preheated using a flame formed by a burner to prevent damage to
refractories (refractory bricks, and the like) in the furnace due
to rapid heating. The flame of the burner used for such
applications is required to have high heat transfer efficiency and
to be able to heat uniformly an object to be heated.
[0003] As a method for increasing a heat transfer efficiency of the
burner, for example, a method for increasing the flame temperature
by using an oxygen-enriched air as an oxidizing agent has been
adopted. However, in a conventional burner, since the flame has a
linear shape, there is a tendency to locally heat one point of the
object to be heated, and uniform heating is difficult.
[0004] On the other hand, Patent Documents 1 and 2 disclose a
method capable of performing uniform heating while moving a flame
by using a self-induced oscillating phenomenon of a jet flow and
maintaining high heat transfer efficiency. The burners disclosed in
Patent Documents 1 and 2 employ a nozzle structure that applies the
self-induced oscillating phenomenon in which a jet flow
periodically changes without requiring an external driving force.
Thereby, since a flame direction can be changed periodically, it
becomes possible to perform uniform heating, maintaining high heat
transfer efficiency. As a result, the burners disclosed in Patent
Documents 1 and 2 can uniformly heat over a wide range as compared
with conventional radiant tube burners and the like, and for
example, the burners are suitably used for preheating such as the
tundish.
PRIOR ART DOCUMENTS
Patent Literature
[0005] Patent Document 1: Japanese Unexamined Patent Application,
First Publication No. 2005-113200
[0006] Patent Document 2: Japanese Unexamined Patent Application,
First Publication No. 2013-079753
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0007] The characteristics of the burners performing the
self-induced oscillation disclosed in Patent Documents 1 and 2 can
be controlled by the oscillation period of the jet flow. When an
ejection velocity of a center fluid ejected from a center fluid
ejection outlet of the burner is the same, and the oscillation
period is short, fluid mixing is promoted, convection heat transfer
is enhanced, and uniform heat transfer distribution can be
obtained. On the other hand, when the oscillation period is long,
the combustion is slow, and the radiant heat transfer is enhanced,
and a long flame can be obtained. In order to control the
oscillation period while keeping the ejection velocity constant,
the flow of the fluid in a connection pipe provided for generating
the self-induced oscillation may be controlled. An arbitrary
oscillation period can be obtained by appropriately selecting the
length of the connection pipe.
[0008] However, in the burners disclosed in Patent Documents 1 and
2, since the oscillation period in the flow rate of the center
fluid is fixed, the combustion characteristic cannot be changed.
For example, a method of making the connection pipe removable is
also conceivable. However, for example, when the oscillation period
is controlled using a flexible cable as the connection pipe, it is
necessary to increase the cable length in order to increase the
oscillation period, which causes a problem that the apparatus
becomes complicated. In addition, when the frequency is changed
while the burner is operated, the connection pipe needs to be
exchanged in the combustion state, which may cause danger in
handling the connection pipe in which the fluid has flowed into the
inside.
[0009] The present invention has been made in view of the above
problems, and an object of the present invention is to provide an
oxygen-enriched burner which can change any oscillation period with
a simple operation and uniformly heat an object to be heated with
an excellent heat transfer efficiency when heating the object to be
heated while moving the flame with the self-induced oscillation,
and a method for heating using an oxygen enriched burner.
Means to Solve the Problem
[0010] In order to solve the problems, the present invention
provides the following oxygen-enriched burners and methods for
heating using an oxygen-enriched burner.
[0011] (1) An oxygen-enriched burner which is configured to eject
an oxygen-enriched air or a fuel gas from a plurality of fluid
ejection outlets provided at the tip surface and burns them,
[0012] wherein a plurality of the fluid ejection outlets include a
center fluid ejection outlet and a peripheral fluid ejection
outlet,
[0013] a pair of openings are provided at opposite positions on
side walls of a fluid ejection flow path of the center fluid
ejection outlet,
[0014] a pair of the openings are communicated with a communication
portion,
[0015] an interval between a pair of the side walls downstream of
the opening in the fluid ejection flow path is gradually expanded
toward the downstream side,
[0016] the peripheral fluid ejection outlet is provided around the
center fluid ejection outlet,
[0017] the communication portion includes a first communication
pipe and a second communication pipe each having a first end
connected to a pair of the openings, and at least one communication
element connected to a second end of the first communication pipe
and the second communication pipe and communicating the first
communication pipe and the second communication pipe.
[0018] (2) The oxygen-enriched burner according to (1), wherein a
plurality of the communication elements are provided in parallel
between the first communication pipe and the second communication
pipe.
[0019] (3) The oxygen-enriched burner according to (2), wherein at
least one of an inner diameter and a length of a plurality of the
communication elements is different.
[0020] (4) The oxygen-enriched burner according to any one of (1)
to (3), wherein the first communication pipe, the second
communication pipe, and the communication element are detachably
connected.
[0021] (5) The oxygen-enriched burner according to any one of (1)
to (4), wherein the communication portion includes an on-off valve
provided between the first communication pipe and the communication
element and between the second communication pipe and the
communication element.
[0022] (6) A method for heating using an oxygen-enriched burner,
wherein an object to be heated is heated using the oxygen-enriched
burner according to any one of (1) to (5) while causing the fluid
ejected from the center fluid ejection outlet to the self-induced
oscillation in an expansion direction of the fluid ejection flow
path,
[0023] (7) The method for heating using an oxygen-enriched burner
according to (6), wherein a period of the self-induced oscillation
of the fluid ejected from the center fluid ejection outlet is 30
seconds or less.
Effects of the Invention
[0024] As explained above, the oxygen-enriched burner according to
the present invention is an oxygen-enriched burner which moves a
flame by the self-induced oscillation, wherein the communication
portion which communicates a pair of the openings provided on the
side walls of the fluid ejection flow path of the center fluid
ejection outlet includes the communication element which
communicates the first communication pipe and the second
communication pipe. Thereby, the oxygen-enriched burner according
to the present invention can change and control to any oscillation
period with a simple operation. Therefore, during the operation of
the oxygen-enriched burner, it is possible to change the combustion
characteristics with a simple switching operation and to heat the
object to be heated uniformly with excellent heat transfer
efficiency. Furthermore, by ejecting the oxygen-enriched air from
the peripheral fluid ejection outlet toward the fuel gas ejected
from the center fluid ejection outlet, the combustion efficiency is
improved, and the amount of NOx emissions can be effectively
suppressed.
[0025] A heating method using an oxygen-enriched burner according
to the present invention is a heating method using the
oxygen-enriched burner according to the present invention. For this
reason, as described above, the oscillation period of the flame due
to the self-induced oscillation can be changed by a simple
operation as necessary, and the object to be heated can be
uniformly heated with excellent heat transfer efficiency.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a diagram schematically showing an oxygen-enriched
burner according to an embodiment of the present invention, and is
a plan view showing an example of a positional relationship between
a center fluid ejection outlet and a peripheral fluid ejection
outlet.
[0027] FIG. 2 is a diagram schematically showing an oxygen-enriched
burner according to an embodiment of the present invention, and is
a cross-sectional view of the burner taken along line A-A shown in
FIG. 1.
[0028] FIG. 3 is a diagram schematically showing an oxygen-enriched
burner according to an embodiment of the present invention, and
FIGS. 3A and 3B are conceptual diagrams showing a oscillation state
of an ejection direction of a center fluid in the burner shown in
FIGS. 1 and 2.
[0029] FIG. 4 is a diagram schematically showing an oxygen-enriched
burner and a method for heating using an oxygen-enriched burner in
Examples, and FIGS. 4A and 4B are schematic diagrams showing an
example of a positional relationship between a burner and a
thermocouple.
[0030] FIG. 5 is a diagram schematically showing an oxygen-enriched
burner and a heating method using an oxygen-enriched burner in
Examples 1 and 2, and is a graph showing a temperature distribution
in a furnace with respect to a distance from a burner axis.
[0031] FIG. 6 is a diagram schematically showing an oxygen-enriched
burner and a method for heating an oxygen-enriched burner in
Examples, and FIGS. 6A and 6B are schematic diagrams showing an
example of a positional relationship between a burner and a
heatsink member.
[0032] FIG. 7 is a diagram schematically showing an oxygen-enriched
burner and a method for heating an oxygen-enriched burner in
Example 3 and 4, and FIGS. 6A and 6B are schematic diagrams showing
an example of a positional relationship between a distance from a
tip surface of a burner and an amount of heat transferred.
[0033] FIG. 8 is a diagram schematically showing an oxygen-enriched
burner and a method for heating an oxygen-enriched burner in
Example 5, and is a graph showing a relationship between a
self-induced oscillation period and an amount of NOx emission.
DETAILED DESCRIPTION OF THE INVENTION
[0034] Hereinafter, an oxygen-enriched burner and a method for
heating using an oxygen-enriched burner which is an embodiment
according to the present invention will be described with reference
to figures as appropriate.
[0035] In the drawings used in the following description, in order
to make the features easy to understand, the features may be
enlarged for the sake of convenience, and the dimensional ratio of
each component may be limited to the same as the actual one. In
addition, the materials and the like exemplified in the following
description are merely examples, and the present invention is not
necessarily limited to them, and can be appropriately changed and
implemented without changing the gist of the invention.
[0036] <Burner>
[0037] Hereinafter, the structure and a method for combusting of an
oxygen-enriched burner according to the present invention will be
described in detail.
[0038] [Structure of Burner]
[0039] FIGS. 1 to 3 are diagrams for explaining a structure of an
oxygen-enriched burner 1 (hereinafter sometimes abbreviated as
burner 1) according to an embodiment of the present invention. FIG.
1 is a plan view showing an example of a positional relationship
between a center fluid ejection outlet and a peripheral fluid
ejection outlet. FIG. 2 is a sectional view (cross-sectional view)
taken along line A-A shown in FIG. 1. FIG. 3 is a conceptual
diagram showing oscillation states of an ejection direction of a
fluid in the burner 1 according to one embodiment of the present
invention. Moreover, FIGS. 1 to 3 are schematic diagrams showing an
arrangement relationship and a size of each fluid ejection outlet
and opening, and the like, and some of the detailed parts such as a
tube wall as a nozzle are omitted.
[0040] As shown in FIGS. 1 to 3, the burner 1 according to the
present embodiment ejects at least one of a fuel gas G1 and an
oxygen-enriched air G2 from a plurality of fluid ejection outlets
provided at the tip surface of the burner 1, and burns them.
[0041] Specifically, the burner 1 of the present embodiment
includes a plurality of fluid ejection outlets including a center
fluid ejection outlet 2, and a peripheral fluid ejection outlet
3.
[0042] A pair of opening 62a and 62b are provided at opposing
positions on side walls 61 which form a fluid ejection flow path 6
that forms the center fluid ejection outlet 2. A pair of the
openings 62a and 62b are communicated with each other by a
communication portion 7.
[0043] Further, a distance between a pair of the side walls 63a and
63b forming the fluid ejection flow path 6 on the downstream side
of the opening 62a and 62b is gradually expanded toward the
downstream side. That is, when the burner 1 is viewed from above,
the fluid ejection flow path 6 on the downstream side of the
opening 62a, 62b has a fan shape. Moreover, the peripheral fluid
ejection outlet 3 is arranged around the center fluid ejection
outlet 2.
[0044] In the burner 1 of the present embodiment, the fuel gas G1
or the oxygen-enriched air G2 is ejected from the center fluid
ejection outlet 2 and the peripheral fluid ejection outlet 3,
respectively, but any gas may be ejected from which ejection
port.
[0045] In the burner 1 of the present embodiment, the fuel gas G1
is ejected from the center fluid ejection outlet 2, and the
oxygen-enriched air G2 is ejected from the peripheral fluid
ejection outlet 3.
[0046] The center fluid ejection outlet 2 is an opening (nozzle)
that ejects the fuel gas G1 when the fuel gas G1 is supplied to the
fluid ejection flow path 6. As will be described later, since the
cross section of the fluid ejection flow path 6 in the direction
orthogonal to the flow direction of the fluid is substantially
rectangular, the shape of the center fluid ejection outlet 2 is
rectangular.
[0047] A center fluid supply line (not shown) is connected to an
inlet 6a of the fluid ejection flow path 6. Thereby, the fuel gas
G1 can be introduced into the fluid ejection flow path 6, and the
fuel gas G1 is ejected from the center fluid ejection outlet 2.
[0048] As described above, the cross section of the fluid ejection
flow path 6 in the direction orthogonal to the flow direction of
the fluid (gas) is substantially rectangular. Side surfaces of the
substantial rectangular are formed by a pair of the side walls 61
and 61 described above. The side walls 61 and 61 are provided with
a pair of the openings 62a and 62b so as to face each other.
Further, as shown in FIG. 2, a pair of the openings 62a and 62b are
communicated by a communication portion 7.
[0049] As described above, the side surfaces of the fluid ejection
flow path 6 located downstream of the opening 62a and 62b are
formed by a pair of the side walls 63a and 63b. An interval of a
pair of the side walls 63a, 63b is gradually expanded toward the
downstream. The cross section of the fluid ejection flow path 6
along the flow direction of the fluid (gas) located downstream of
the openings 62a and 62b has a fan shape. That is, the side
surfaces of the fluid ejection flow path 6 positioned downstream of
the openings 62a and 62b are formed by a pair of the side walls 63a
and 63b arranged in a substantially V shape.
[0050] On the other hand, the fluid ejection flow path 6 positioned
on the upstream side of a pair of the openings 62a and 62b is
formed as a rectangular tube-shaped flow path 64 in which the
opposed side walls 61 and 61 extend substantially in parallel. The
shape of the cross section along the flow direction of the fluid
(gas) is substantially rectangular.
[0051] The burner 1 of the present embodiment has a pair of the
openings 62a and 62b arranged opposite to each other on a pair of
the side walls 61 and 61 forming a fluid ejection flow path 6, and
a pair of the openings 62a and 62b are communicated with each other
through the communication portion 7. Thereby, the so-called
flip-flop nozzle self-induced oscillation can be generated in the
fuel gas G1 ejected from the center fluid ejection outlet 2.
[0052] That is, as shown in FIGS. 3A and 3B, when the fluid (fuel
gas G1) flowing through the flow path 64 of the fluid ejection flow
path 6 passes between a pair of the openings 62a and 62b and flows
between a pair of the side walls 63a and 63b arranged in a
fan-shaped cross section, the fluid is ejected from the center
fluid ejection outlet 2 while self-induced oscillation so as to
alternately contact one side wall 63a and the other side wall 63b.
In FIG. 1, an arrow R in FIG. 1 means a self-induced oscillating
direction of the fluid.
[0053] The amplitude and frequency of the fluid due to the
self-induced oscillation vary according to various conditions such
as the dimensions of the opening 62a and 62b, a air of the side
walls 63a and 63b, and the communication portion 7, and the flow
velocity of the fluid.
[0054] In the oxygen-enriched burner 1 according to the present
embodiment, the fluid ejected from the center fluid ejection outlet
2 is oscillated at a desired angle and frequency within certain
ranges by setting the dimensions and the number of installed
communication elements 73 in the communication portion 7. That is,
according to the oxygen-enriched burner of the present embodiment,
the fluid ejected from the center fluid ejection outlet 2 can be
oscillated at a desired angle and frequency within certain ranges
with a simple configuration and a simple operation.
[0055] Hereinafter, the communication portion 7 which is one of the
characteristic parts of the oxygen-enriched burner 1 of the present
embodiment will be described.
[0056] The communication portion 7 includes a first communication
pipe 71 and a second communication pipe 72 each having a first end
71a, 72a connected to a pair of the openings 62a, 62b, and at least
one tubular communication element 73 connected to a second end 71b,
72b of the first communication pipe 71 and the second communication
pipe 72 and communicating the first communication pipe 71 and the
second communication pipe 72.
[0057] That is, the communication portion 7 includes the first
communication pipe 71, the second communication pipe 72, and a
plurality of the communication elements 73. The first end 71a of
the first communication pipe 71 is connected to the opening 62a and
the second other end 71b is connected to the communication element
73. The first end 72a of the second communication pipe 72 is
connected to the opening 62b, and the second end 72b is connected
to the communication element 73.
[0058] In FIG. 2, the communication portion 7 includes the first
communication pipe 71, the second communication pipe 72, and three
communication elements 73 connected in parallel between the first
communication pipe 71 and the second communication pipe 72. That
is, as shown in FIG. 2, the first communication pipe 71 has three
second ends 71b, 71b, 71b. Similarly, the second communication pipe
72 also has three second ends 72b, 72b, 72b. The second ends 71b,
71b, 71b of the first communication pipe 71 communicate with the
second ends 72b, 72b, 72b of the second communication pipe 72
through three communication elements 73 (73A, 73B, 73C). That is,
the three communication elements 73 (73A, 73B, 73C) are arranged in
parallel to the first communication pipe 71 and the second
communication pipe 72.
[0059] In the oxygen-enriched burner 1 of the present embodiment,
self-induced oscillation is generated by a flip-flop nozzle by
communicating a pair of the openings 62a and 62b with the
communication portion 7.
[0060] The communication portion 7 in the oxygen-enriched burner 1
of the present embodiment further includes an on-off valve 74
provided between the first communication pipe 71 and the
communication element 73, and an on-off valve 74 provided between
the second communication pipe 72 and the communication element 73.
That is, the on-off valve 74 is connected to each of one ends 73a,
73a, 73a and the other ends 73b, 73b, 73b of communication elements
73A, 73B, and 73C.
[0061] Since the burner 1 of the present embodiment includes the
on-off valve 74, it is possible to select only any communication
element among the communication elements 73A, 73B, and 73C. Of
course, by operating the on-off valve 74, all the communication
elements 73A, 73B, 73C can be used simultaneously or all can be
stopped.
[0062] In the burner 1 of the present embodiment, the flow rate and
flow velocity of the fluid flowing through each communication
element can be set to different values by changing the inner
diameters and lengths (full lengths) of a plurality of the
communication elements 73A, 73B, and 73C. That is, by operating the
on-off valve 74 and selecting an arbitrary communication element,
the flow rate and flow velocity of the fluid in the communication
portion 7 can be adjusted, and the self-induced oscillation period
can be set to an arbitrary period. The longer the communication
element 73 is, the longer the self-induced oscillation period of
the fluid ejected from the center fluid ejection outlet 2 is. The
smaller the inner diameter of the communication element 73, the
longer the self-induced oscillation period.
[0063] The flow rate and flow velocity of the fluid in the
communication element 73 can also be changed by providing a baffle
plate or the like in the communication element 73.
[0064] The relationship between a length len of the communication
element, which is made dimensionless by the diameter or the
equivalent diameter (when the channel cross section is not
circular) D of the fluid ejection flow path 6 and a cross section S
of the communication element 73, and a oscillation frequency
(Strouhal number) St, which is made dimensionless by the diameter
or the equivalent diameter D and the ejection velocity U of the
center fluid, is expressed by the expression {len=k1/St (k:
proportional constant)}, and is linear. hat is, the relationship
between the length len of the communication element and the
frequency St is also expressed by the expression {1/St=D/(tU) (t:
oscillation period)}. However, the diameter or the equivalent
diameter D of the fluid ejection flow path 6 and the ejection
velocity U of the center fluid are determined. For this reason, it
is possible to change the oscillation period t by using
communication elements 73 having different communication element
lengths len.
[0065] As shown in FIG. 2, when the cross section of the fluid
ejection flow path 6 in the direction orthogonal to the flow
direction of the fluid is rectangular, the interval between the
side walls 61 and 61 located on the upstream side with respect to a
pair of the openings 62a and 62b can be the equivalent diameter
D.
[0066] The oxygen-enriched burner 1 of the present embodiment
includes the communication elements 73A, 73B, and 73C having
different specifications, and the oscillation period t can be
easily changed by arbitrarily selecting them.
[0067] In the oxygen-enriched burner 1 of the present embodiment,
the first communication pipe 71 and the communication element 73
may be detachably connected, or the second communication pipe 72
and the communication element 73 may be detachably connected. The
communication element 73 may be detachably connected to the on-off
valve 74. By detachably attaching the communication element 73 to
the first communication pipe 71 and the second communication pipe
72 (or the on-off valve 74), it is possible to easily replace the
communicating element 73 with a communicating element which can
obtain a flow rate and a flow velocity of the fluid according to
the characteristics of an object to be heated.
[0068] Various methods can be employed to make the communication
element 73 attachable to and detachable from the first
communication pipe 71 and the second communication pipe 72 (or the
on-off valve 74). For example, both ends of the communication
element 73 and the first communication pipe 71 and the second
communication pipe 72 may be sealed with an O-ring. A screwing
structure may be provided at both ends of the communication element
73 and the first communication pipe 71 and the second communication
pipe 72.
[0069] The opening angle of a pair of the side walls 63 in the
fluid ejection flow path 6, that is, the opening angle a (see FIG.
2) of the center fluid ejection outlet 2 is not particularly
limited, and may be set in consideration of a desired opening angle
of the flame. However, from the viewpoint of stably generating
oscillation in the ejection direction of the fluid and realizing
uniform heating, the angle is preferably 90.degree. or less.
[0070] In FIG. 2, the communication portion includes three
communication elements 73a, 73b, and 73c, but is not limited
thereto. For example, the number of the communication elements 73
may be one or two, or four or more communication elements 73 may be
provided.
[0071] Moreover, in the burner 1 of the present embodiment, the
ejection amount of the center fluid (the fuel gas G1) ejected from
the center fluid ejection outlet 2 and the ejection amount of the
peripheral fluid (the oxygen-enriched air G1) ejected from the
peripheral fluid ejection outlet 3 are preferably individually
controllable. For example, a flow rate control device may be
provided in the line that is connected to each ejection outlet and
supplies each fluid.
[0072] As shown in FIG. 1, the peripheral fluid ejection outlet 3
is arranged around the center fluid ejection outlet 2 so as to
surround the center fluid ejection outlet 2.
[0073] A peripheral fluid supply line (not shown) is connected to
the peripheral fluid ejection outlet 3. With the introduction of
the oxygen-enriched air G2, the peripheral fluid ejection outlet 3
becomes opening (nozzle) to eject gas.
[0074] Here, "the peripheral fluid ejection outlet 3 is arranged
around the center fluid ejection outlet 2" in the present
embodiment means that the peripheral fluid ejection outlet 3 is
arranged so as to surround the center fluid ejection outlet 2, and
that the center fluid ejection outlet 2 and the peripheral fluid
ejection outlet 3 are arranged at adjacent positions.
[0075] By arranging the peripheral fluid ejection outlet 3 around
the center fluid ejection outlet 2, the oxygen-enriched air G2 can
be ejected from a position adjacent to the position at which the
fuel gas G1 is ejected.
[0076] In the oxygen-enriched burner of present embodiment, the
peripheral fluid ejection outlet 3 is arranged so as to surround
the center fluid ejection outlet 2, so that the center fluid
ejected from the center fluid ejection outlet 2 (the fuel gas G1)
and the peripheral fluid (the oxygen-enriched air G2) ejected from
the peripheral fluid ejection outlet 3 are effectively mixed. In
addition, since the fluid is ejected from the peripheral fluid
ejection outlet 3 to the outer periphery of the flame, the
reduction region is spread, and the effect of improving the
combustion efficiency when forming the flame is obtained.
[0077] The shape of the peripheral fluid ejection outlet 3 may be a
rectangular shape or a circular shape arranged so as to surround
the center fluid ejection outlet 2. Further, the peripheral fluid
ejection outlet 3 may be configured to surround the center fluid
ejection outlet 2 with a plurality of openings (holes).
[0078] [Method for Combusting Burner]
[0079] Next, a method for combusting the oxygen-enriched burner 1
of the present embodiment will be described.
[0080] In the burner 1 of the present embodiment, the center fluid
ejected from the center fluid ejection outlet 2 is the fuel gas G1,
the peripheral fluid ejected from the peripheral fluid ejection
outlet 3 is the oxygen-enriched air G2, and a flame is formed in an
ejection direction of the fuel gas G1.
[0081] Examples of the fuel gas G1 include natural gas (LNG), but
liquid fuel such as heavy oil may be used.
[0082] Further, as the oxygen-enriched air G2, for example, a mixed
gas of oxygen and air in which the oxygen concentration is
increased as much as possible can be exemplified. Instead of the
air, for example, nitrogen gas, carbon dioxide gas, exhaust gas, or
the like can be used and mixed with oxygen. Moreover, as oxygen
used for the mixed gas, industrial pure oxygen may be used.
[0083] When combusting the burner 1 of the present embodiment, the
fuel gas G1 is ejected from the center fluid ejection outlet 2
while alternately and periodically changing the ejection direction
by the self-induced oscillation (see FIGS. 3A and 3B). At this
time, the oxygen-enriched air G2 (peripheral fluid) is ejected
toward the fuel gas G2 ejected from the center fluid ejection
outlet 2 at a periodically changing angle from the peripheral fluid
ejection outlet 3 so as to wrap the fuel gas G1 and contributes to
the formation of the flame.
[0084] As the oxygen-enriched air G2 is ejected toward the fuel gas
G1, the combustion efficiency is improved, and the amount of NOx
emission can be effectively suppressed. Moreover, the heat transfer
efficiency by the flame improves and it becomes possible to heat
the object to be heated uniformly.
[0085] Moreover, the switching period (oscillation period t) of the
ejection direction of the fuel gas G1 by the self-induced
oscillation is not particularly limited. What is necessary is just
to set the switching period suitably in a range which can be heated
uniformly with the excellent heat-transfer efficiency also in the
position away from the center axis of the burner. As described
later, the oscillation period t for obtaining such an effect is
preferably set to oscillation period t=30 seconds or less.
[0086] The oxygen-enriched burner 1 of the present embodiment is a
burner that oscillates the flame by the self-induced oscillation,
and includes the communication portion 7. Therefore, the
oscillation period t of the fluid ejected from the center fluid
ejection outlet 2 can be arbitrarily changed and controlled. As a
result, when the oxygen-enriched burner 1 is operated, the
combustion characteristic can be changed by a simple switching
operation, and the object to be heated can be uniformly heated with
excellent heat transfer efficiency.
[0087] <Method for Heating Using Oxygen-Enriched Burner>
[0088] The method for heating according to the present invention is
a method for heating an object to be heated, such as a tundish
while the oxygen-enriched burner 1 is used to cause the
self-induced oscillation of the fluid ejected from the center fluid
ejection outlet 2 in the expanding direction of the fluid ejection
flow path 6. Since the method for heating of the present invention
is a method for heating an object to be heated using the
oxygen-enriched burner 1 described above, when heating the object
to be heated by the flame that oscillates with the self-induced
oscillation, the object to be heated can be uniformly heated with
excellent heat transfer efficiency while changing the oscillation
period t of the self-induced oscillation of the fluid ejected from
the center fluid ejection outlet 2.
[0089] The object to be heated in the method for heating of the
present invention is not particularly limited. As one embodiment, a
ladle and a tundish (not shown), or the like that receives pig iron
used in the steel making process described above can be given.
[0090] The method for heating of the present embodiment is a method
for heating an object to be heated such as a ladle or a tundish
using the burner 1, wherein the oscillation period t of the fluid
ejected from the center fluid ejection outlet 2 can be arbitrarily
changed and controlled. Thereby, when the burner 1 is operated, the
combustion characteristic can be changed by a simple switching
operation, and the object to be heated can be uniformly heated with
excellent heat transfer efficiency.
[0091] In the method for heating of the present embodiment, the
period of the self-induced oscillation (oscillation period t) of
the fluid ejected from the center fluid ejection outlet 2 is not
particularly limited and can be set as appropriate in consideration
of the characteristics of the object to be heated. Since various
objects to be heated can be uniformly heated over a wide area, the
oscillation period t=30 seconds or less is preferable.
[0092] Note that the object to be heated by the method for heating
using the burner 1 of the present embodiment is not limited to a
ladle or a tundish used in the steel making process. For example,
in the case of heating various objects to be heated that require
high temperature and uniform heating, the present invention can be
applied without any limitation.
[0093] <Effects>
[0094] As explained above, the oxygen-enriched burner of the
present embodiment includes the center fluid ejection outlet 2 and
the peripheral fluid ejection outlet 3 provided around the center
fluid ejection outlet 2, a pair of the openings 62a, 62b are
provided at opposite positions on the side walls 61, 61 of the
fluid ejection flow path 6 of the center fluid ejection outlet 2, a
pair of the openings 62a, 62b are communicated with each other by
the communication portion 7, the first communication pipe 71 and
the second communication pipe 72 each having the first end 71a, 72a
connected to a pair of the openings 62a, 62b, and at least one
communication element 73 connected to the second ends 71b, 72b of
the first communication pipe 71 and the second communication pipe
72 and communicating the first communication pipe 71 and the second
communication pipe 72.
[0095] Thus, in the oxygen-enriched burner 1 that oscillates the
flame by the self-induced oscillation, the communication portion 7
that communicates a pair of the openings 62a and 62b includes the
communication element 73 that communicates the first communication
pipe 71 and the second communication pipe 72. Thereby, it can
change and control to arbitrary oscillation periods with a simple
structure and a simple operation. Therefore, when the
oxygen-enriched burner 1 is operated, the combustion
characteristics can be changed by a simple switching operation, and
the object to be heated can be uniformly heated with excellent heat
transfer efficiency.
[0096] Furthermore, since the center fluid ejection outlet 2 and
the peripheral fluid ejection outlet 3 are provided, the
oxygen-enriched air G2 can be ejected toward the fuel gas G1. As a
result, the combustion efficiency can be improved, and the amount
of NOx emission can be effectively suppressed.
[0097] Moreover, the method for heating using an oxygen-enriched
burner of the present embodiment is a method for heating using the
oxygen-enriched burner 1 described above. For this reason, similar
to the oxygen-enriched burner 1, the oscillation period t of the
flame caused by the self-induced oscillation can be changed by a
simple operation as necessary. Furthermore, the object to be heated
can be uniformly heated with excellent heat transfer
efficiency.
EXAMPLES
[0098] Hereinafter, the oxygen-enriched burner and the method for
heating using a burner according to the present invention will be
described in more detail with reference to Examples, but the
present invention is not limited to the following Example, and can
be appropriately modified and implemented without changing the gist
of the invention.
[0099] <Burner Specifications and Operating Conditions>
[0100] In the Examples, as shown in FIGS. 1 to 3, a self-induced
oscillation type oxygen-enriched burner 1, which includes the first
communication pipe 71 and the second communication pipe 72 each
having the first end 71a, 72a connected to a pair of the openings
62a, 62b, and three communication element 73a, 73b, 73c connected
to the second ends 71b, 72b of the first communication pipe 71 and
the second communication pipe 72 and communicating the first
communication pipe 71 and the second communication pipe 72, was
prepared. Using the prepared burner 1, a combustion test was
performed under the following conditions.
[0101] In the Examples, the opening angle a of the center fluid
ejection outlet 2 of the burner 1 shown in FIG. 2 was adjusted to
30.degree..
[0102] In the Examples, propane gas was used as the fuel gas G1,
and a gas having an oxygen enrichment rate of 40% was used as the
oxygen-enriched air G2. The fuel gas G1 was flowed to the center
fluid ejection outlet 2 and the oxygen-enriched air G2 was flowed
to the peripheral fluid ejection outlet 3 to form a flame.
[0103] Burner operation conditions were as follows: the flow rate
of the fuel gas G1 (propane gas) was 13 Nm.sup.3/h, the flow rate
of the oxygen-enriched air G2 was 170 Nm.sup.3/h, and combustion
was performed at an oxygen ratio of 1.05. Moreover, the oxygen
ratio refers to the proportion of oxygen when the amount of oxygen
necessary for complete combustion of the fuel gas was 1.
[0104] Further, in the Examples, the burner 1 was combusted in a
test furnace (not shown), and the communication element 73 was
switched during combustion, thereby changing the oscillation period
t of the fuel gas G1 due to the self-induced oscillation in the
center fluid ejection outlet 2. After reaching a steady state,
measurement was performed for each evaluation items described in
the following Examples.
[0105] In Example, the possibility of changing the oscillation
period t by switching the communication element 73 described below
was also evaluated. At this time, the equivalent diameter D of the
fluid ejection flow path 6 was 10 mm, and the ejection velocity U
of the fuel gas ejection G1 was adjusted to 40 m/s.
Examples 1 and 2
[0106] In Examples 1 and 2, the temperature distribution in the
combustion furnace when the oxygen-enriched burner 1 was combusted
by the self-induced oscillation and the communication period 73 was
changed by switching the communication element 73 was evaluated
using thermocouples. FIGS. 4A and 4B are schematic diagrams showing
the positional relationship between the burner 1 and the
thermocouples in the Examples 1 and 2.
[0107] In Examples 1 and 2, a plurality of the thermocouples were
arranged along the expanding direction of the liquid election flow
path 6 at positions 500 mm forward from the tip surface of the
burner 1, as shown in FIG. 4B, and 300 mm below the center axis in
the height direction of the burner 1 as shown in FIG. 4B.
[0108] In Examples 1 and 2, the evaluation was performed using the
communication elements C1 and C2 having a communication element
length len and 1/St (St: frequency) shown in Table 1 below.
[0109] As described above, the relationship between the length len
of the communication element and 1/St is expressed by the equation
{len=k1/St (k: proportional constant)} and the equation
{1/St=D/(tU) (t: oscillation period)}. Therefore, in the Examples 1
and 2, the diameter or the equivalent diameter D of the fluid
ejection flow path 6 and the ejection velocity U of the center
fluid were determined in advance, and the oscillation period t was
changed by using communication elements having different
communication element lengths len shown in Table 1 below.
TABLE-US-00001 TABLE 1 Length len of Oscillation Communication
Communication period Element Element (mm) 1/St t (sec.) Example 1
C1 800 400 0.1 Example 2 C2 4000 4000 1 Example 3 C3 20000 20000
5
[0110] In Examples 1 and 2, the temperature when the self-induced
oscillation combust was generated and the steady state was reached
was measured by each thermocouple in the test apparatus shown in
FIGS. 4A and 4B.
[0111] The distance from the center axis in the self-induced
oscillation direction of the burner 1, that is, the gas ejection
direction when the self-induced oscillation is not performed is the
distance from the center axis of the burner is 0 [mm]. The
relationship between the amplitude of the gas ejection direction
during the self-induced oscillation and the furnace temperature,
that is, the relationship between the position of the thermocouples
and the furnace temperature is shown in the graph of FIG. 5 as data
representing the temperature distribution in the furnace.
[0112] In the graph of FIG. 5, Example 1 is a measurement result in
oscillation period t=0.1 second (see Table 1), and Example 2 is a
measurement result in oscillation period t =1 second (see Table 1).
As shown in FIG. 5, it can be understood that Example 1 with a
short oscillation period t had a flat (uniform) temperature
distribution compared to Example 2.
[0113] From the evaluation results in Examples 1 and 2, it is
confirmed that the oscillation period t could be switched by
changing the length of the communication element 73, and the
temperature distribution could be changed by changing the
oscillation period t, that is, the heating characteristics were
changed.
[0114] It is clear that by using the oxygen-enriched burner
according to the Examples, any combust state could be obtained by
switching the communication element during the burner operation and
changing the oscillation period t.
Examples 3 and 4
[0115] In Examples 3 and 4, the change in the flame length in the
oxygen-enriched burner that was combusted with the self-induced
oscillation, and the change in the heat transfer characteristics
associated therewith were evaluated.
[0116] FIGS. 6A and 6B are schematic views showing the positional
relationship between the burner 1 and the thermocouples in the
Examples 3 and 4.
[0117] As shown in FIG. 6A, a plurality of heatsink members were
arranged along the ejection direction of the combust gas from the
center fluid ejection outlet 2, that is, the flame formation
direction at positions 300 mm below the center axis in the height
direction of the burner 1.
[0118] In the Examples 3 and 4, the self-induced oscillation
combustion was generated in the test apparatus shown in FIGS. 6A
and 6B, and the heat transfer efficiency to the heatsink members in
a steady state was measured. At this time, the temperature of the
heatsink members was confirmed by measuring the surface temperature
using a thermocouple (not shown).
[0119] The relationship between the distance from the tip surface
of the burner 1 to the heatsink member and the amount of heat
transferred is shown in the graph of FIG. 7 as data representing
the amount of heat transferred distribution in the furnace.
[0120] In the graph of FIG. 7, Example 3 is a measurement result in
the same oscillation period t=0.1 second (see Table 1) as Example
1, and Example 4 is a measurement result in the same oscillation
period t=1 second as in Example 2 (For the length len of the
communication element, 1/St, and oscillation period tin Example 3,
see communication element C3 in Table 1).
[0121] As shown in FIG. 7, it can be understood that the slow
combustion was promoted in Example 4 having a longer oscillation
period t than that in Example 3 than Example 3, the radiant heat
transfer was enhanced, and the heat transfer efficiency was higher.
In addition, it is revealed that the flame length was longer in
Example 4, and a higher amount of heat transferred distribution was
obtained even farther from the tip surface of the burner 1.
Example 5
[0122] In Example 5, a combustion test with the self-induced
oscillation using the burner 1 was performed under the same
conditions as in Example 1, and NOx emission characteristics were
evaluated except that the oscillation period t was changed at a
plurality of periods (0.1 second, 0.5 second, 1 second, and 5
seconds) shown in the graph of FIG. 8.
[0123] The graph of FIG. 8 shows the relationship between the
oscillation period t and the amount of NOx emission in the Example
5.
[0124] As shown in FIG. 8, in Example 5, it is confirmed that the
NOx emission amount decreased as the oscillation period t
increased. This is thought to be because the fuel gas and the
oxygen-enriched air were slightly mixed with each other and became
a slowly combust state, and the reduction region was formed, so
that the amount of NOx emission was suppressed.
[0125] From the results of the Examples described above, it is
clear that the oscillation period can be changed and controlled
arbitrarily with a simple configuration and a simple operation in
the oxygen-enriched burner according to the Examples. It is also
clear that the combustion characteristics can be changed by a
simple switching operation during the burner operation.
Furthermore, it is also clear that the object to be heated can be
uniformly heated with excellent heat transfer efficiency, and the
amount of NOx emission can be effectively suppressed.
INDUSTRIAL APPLICABILITY
[0126] The oxygen-enriched burner and the method for heating using
an oxygen-enriched burner according to the present invention are
preferably used for preheating a tundish used for storing and
transporting the molten iron or the molten steel in the steel
producing or iron producing processes. Furthermore, The
oxygen-enriched burner and the method for heating using an
oxygen-enriched burner according to the present invention are very
suitable for various applications in which object to be heated is
heated using a burner.
EXPLANATION OF REFERENCE NUMERAL
[0127] 1 burner
[0128] 2 center fluid ejection outlet
[0129] 3 peripheral fluid ejection outlet
[0130] 6 fluid ejection flow path [0131] 6a introduction port
[0132] 61 (a pair of) side walls [0133] 62a, 62b (a pair of)
openings [0134] 63a one side wall [0135] 63b the other side wall
[0136] 64 (rectangular tube-shaped) flow path
[0137] 7 communication pipe [0138] 71 first communication pipe
[0139] 72 second communication pipe [0140] 71a, 72a first ends of
first and second communication pipes [0141] 71b, 72b second ends of
first and second communication pipes [0142] 73, 73A, 73B, 73C
communication element [0143] 74 on-off valve
[0144] G1 fuel gas
[0145] G2 oxygen-enriched air
[0146] D corresponding diameter of center fluid flow path
* * * * *