Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02713306 2012-04-11
COMBUSTION HEATER
TECHNICAL FIELD
[0001]
The present invention relates a combustion heater that combusts a premixed
gas of a fuel gas and combustion air.
BACKGROUND ART
[0002]
Conventionally, a radiant tube burner has been manufactured in which a
completely premixed gas of a fuel gas and combustion air is combusted in a
heat-resistant round tube (radiator tube) to thereby use the resulting flame
to cause the
radiator tube to be red hot. Such a burner is used as an elongated heat source
without
exposure of a flame in heating furnaces and heaters. Furthermore a combustion
burner
is known in which combustion gas is combusted in an inner tube and a direction
of flow
is varied by collision of a jet of combustion gas with a shield surface
disposed
orthogonally thereto to thereby extract heat from the radiator tube.
[0003]
In this type of combustion heater, since combustion is completed midway in
the radiator tube, disadvantages include the fact that it is difficult to
obtain a uniform
temperature distribution along the entire tube length, and the fact that a
large amount of
nitrogen oxides (NOx) is produced. In Patent Literature 1, a combustion heater
is
disclosed which includes a porous tube having an inner section acting as a
supply
passage for a premixed gas and, a radiator tube disposed coaxially to the
outer periphery
of the porous tube. A premixed gas is ejected radially from the porous tube
and forms
laminar flow. In a medium of the radiator tube and the porous tube, combustion
is
executed on a cylindrical surface between the radiator tube and the porous
tube on
which the rate of flow of the premixed gas balances the flame propagation
speed to
thereby obtain a higher uniform temperature on the whole of the radiator tube
and
facilitate high heat generation and low NOx production.
[Patent Literature 1] Japanese Patent Application, First Publication No. 6-
241419
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DISCLOSURE OF THE INVENTION
[Problem to be Solved by the Invention]
[0004]
However the conventional techniques above entail the following problems.
Since an inner tube disposed on an inner portion of the outer tube that forms
the radiator tube is extremely a high temperature by the combustion gas
flowing on an
outer periphery thereof, there is a chance that the temperature of uncombusted
gas
flowing in the inner tube becomes excessively high and the uncombusted gas
forms a
mixture gas of fuel and an oxidizing agent, thermal damage may be wreaked
result from
spontaneous ignition.
Furthermore residual deformation or the like may be caused by bending of the
inner tube by heat and therefore preferred combustion characteristics (heating
characteristics) may not be obtained.
[0005]
The present invention is proposed in view of the points above and has the
object of providing a combustion heater which suppresses excessive temperature
increase in an inner tube and which improves heating efficiency.
[Means for Solving the Problem]
[0006]
The present invention is configured in the manner below in order to achieve
the
above object.
According to an aspect of the present invention there is provided a combustion
heater
comprising an inner tube having a supply passage for combustion gas in an
inner portion, and
an outer tube disposed to provide a separated combustion space in an outer
periphery of the
inner tube, a hole part for ejecting the combustion gas being formed on a tube
wall of the
inner tube, a radiation promoting surface is disposed on an outer periphery of
the inner tube,
and a supporting member being provided further towards a distal end than the
hole part of the
inner tube and orientated in a direction perpendicular to an axial direction
of the inner tube,
wherein the supporting member is supported to freely displace in an axial
direction of the
outer tube.
Since the combustion heater according to the present invention promotes
emission of heat as radiant heat (heat emission) from the inner tube which is
heated and
undergoes temperature increase, excessive temperature increase in the inner
tube can be
suppressed. Furthermore since the outer tube is heated by radiant heat emitted
from
the inner tube, heating efficiency by the outer tube can be improved. When the
inner
tube has a low temperature, since the heat transfer amount resulting from
radiation is
small, almost no damage is caused due to heating of combustion gas
(uncombusted gas)
in the supply passage (heat transfer by radiant heat is proportional to the
fourth power of
the temperature).
[0007]
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The radiation promoting surface preferably adopts a configuration in which a
coated surface is provided on an outer peripheral surface of the inner tube.
In this manner, the present invention facilitates formation of a radiation
promoting surface by coating a radiation promoting material in the form of a
coating,
paint or the like on an outer peripheral surface of an inner tube.
[0008]
Furthermore in the present invention, a configuration is preferably adopts in
which a radiation promoting surface is provided on an inner peripheral surface
of the
outer tube.
In this manner, in the present invention, radiant heat from the inner tube
(radiation promoting surface) and radiant heat from the flame in the
combustion space
can be effectively absorbed by the outer tube to thereby further improve
heating
efficiency through the outer tube.
[0009]
In the above configuration, a configuration is preferably adopts in which a
radiation promoting surface is a coated layer provided on the inner peripheral
surface.
In this manner, the present invention facilitates formation of a radiation
promoting surface by coating a radiation promoting material in the form of a
coating,
paint or the like on an inner peripheral surface of the outer tube.
The radiation promoting surface may be configured by using the radiation
promoting material to form an inner tube and an outer tube other than the
coated layer.
The radiation promoting surface is preferably formed using a ceramic binder.
[0010]
The present invention preferably adopts a configuration in which a heat
transfer
member is provided to connect the inner tube and the outer tube in the
combustion
space and to transfer heat between the outer tube and the inner tube.
In this manner, in the present invention, since heat in the inner tube can be
transferred to the outer tube through the heat transfer member, excessive
temperature
increase in the inner tube can be suppressed and the heat efficiency through
the outer
tube can be improved.
[0011]
In the present invention, a configuration is preferably adopted in which the
outer peripheral surface of the inner tube has a first region in which a
distance to the
inner peripheral face of the outer tube is shortest, and a second region in
which the
distance is longer than the first region, and the hole part is disposed in the
first region
and forms a stagnation point for combustion gas on an inner peripheral surface
of the
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outer tube.
In this combustion heater, formation and maintenance of a stable flame is
facilitated (in other words, without causing cost increases) by igniting
(lighting)
combustion gas in the periphery of a stagnation point where the flow speed is
approximately zero. In the conventional example, a gas flow speed must be
increased
to form a stagnation point. Consequently a discharge route for combustion gas
cannot
be ensured completely maintained and there is the possibility that the flame
will extend
to the inner peripheral surface of the outer tube and that a flame will only
be formed on
both axial ends sides. In contrast, the present invention forms and retains a
stable
flame on an inner peripheral face of the outer tube facing a hole part by
providing a hole
part in the second region in which the distance to the inner peripheral face
of the outer
tube is short. Furthermore a discharge route for combustion gases can be
ensured
between the inner peripheral face of the outer tube and the second region
including the
region on the opposite side to the first region.
Furthermore in the present invention, since the flame is formed and retained
at
a stagnation point on the inner peripheral face of the outer tube, efficient
heating is
enabled through the outer tube.
[0012]
The inner tube is preferably disposed with an eccentric position to the outer
tube and preferably adopts a configuration in which the hole part is formed in
an outer
peripheral face positioned in an eccentric direction of the inner tube.
In this manner, the present invention easily forms the first region in which
the
distance between the inner peripheral face of the outer tube and the outer
peripheral face
of the inner tube is short.
When the inner tube is disposed in an eccentric position to the outer tube, a
configuration is preferably adopted in which a plurality of inner tubes is
disposed at an
interval in a peripheral direction about the axial center of the outer tube.
In this manner, in the present invention, a plurality of flames can be formed
and
retained at an interval in a peripheral direction with respect to the inner
peripheral face
of the outer tube, and thereby more efficient heating is possible.
Furthermore in the present invention, a configuration can be adopted in which
the inner tube and the outer tube are disposed concentrically.
[0013]
The present invention preferably adopts a configuration in which a supporting
member supports a distal end of the inner tube, that is cantilever supported
at a base end,
between the inner tube and the outer tube, and maintains an interval between
the outer
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peripheral surface of the inner tube and the inner peripheral surface of the
outer tube.
The supporting member may be tabular, or may be rod-shaped and suspended
between
the outer tube and the inner tube.
In this manner, in the present invention, it is possible to prevent production
of a
vibration in the distal end of the inner tube which results in loss of a fixed
interval
between the outer peripheral face of the inner tube and the inner peripheral
face of the
outer tube at a base end and a distal end and thereby ensure a fixed interval
between the
first region forming the hole part and the inner peripheral surface of the
outer tube.
Consequently, stagnation points can be continuously formed in a stable manner
and
thereby formation and maintenance of a stable and continuous flame is
possible.
[0014]
The present invention preferably adopts a configuration in which a stagnation
point formation member is provided facing the hole part along an axial
direction of the
combustion space to thereby form a stagnation point of combustion gases
ejected from
the hole part.
Thus in the combustion heater according to the present invention, formation
and maintenance of a stable flame is facilitated (in other words, without
causing cost
increases) by igniting (lighting) combustion gas in the periphery of a
stagnation point
formed on a surface of the stagnation point formation member and where the
flow speed
is approximately zero. In the conventional example, a high gas flow speed is
required
to form the stagnation point and consequently a discharge route for combustion
gas
cannot be maintained and there is the possibility that the flame will extend
to the inner
peripheral surface of the outer tube and that a flame will only be formed on
both axial
ends. In contrast, the present invention forms and retains a stable flame on
the surface
of the stagnation point formation member facing the hole part and a discharge
route for
exhaust gases can be maintained in a region in which the inner tube and the
stagnation
point formation member are not facing.
[0015]
A configuration is preferably adopted in which the stagnation point formation
member is disposed coaxially to the outer tube, and the inner tube includes a
plurality of
hole parts oriented toward the central axis and disposed around the central
axis.
In this manner, in the present invention, a stable flame and a stagnation
point
for combustion gases can be formed and maintained around the central axis of
the outer
tube and thereby enable heating of the outer tube while suppressing the
temperature
distribution.
[0016]
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In the present invention, a configuration is preferably adopted which includes
a
supporting member which supports a distal end of the stagnation point
formation
member and the inner tube, that is cantilever supported at a base end, with
the outer tube,
and maintains an interval between the outer peripheral surface of the inner
tube and the
stagnation point formation member, and the inner peripheral surface of the
outer tube.
The supporting member may be tabular, or may be rod-shaped and suspended
between
the outer tube and the inner tube.
In this manner, in the present invention, it is possible to prevent production
of a
vibration in the distal end of the inner tube and the stagnation point
formation member
which results in loss of a fixed interval between the outer peripheral face of
the
stagnation point formation member and the inner tube, and the inner peripheral
face of
the outer tube at a base end and distal end. A fixed interval can be ensured
between
the hole parts and the inner peripheral surface of the outer tube and the
stagnation point
formation member. Consequently, stagnation points can be continuously formed
in a
stable manner and thereby formation and maintenance of a stable and continuous
flame
is possible.
[0017]
In the present invention, a configuration is preferably adopted in which the
supporting member is disposed further towards the distal end than the hole
part
positioned furthest towards the distal end, and has a size which covers the
whole
combustion space.
In this manner, in the present invention, CO production resulting from
retention
and non-combustion of combustion gas in the low-temperature distal end of the
outer
tube can be avoided.
[0018]
The supporting plate preferably adopts a configuration of freely displacing in
an axial direction relative to the outer tube.
In this manner, in the present invention, even when there is a large
difference in
the amount of thermal expansion particularly in an axial direction because of
a
temperature difference between the inner tube and the outer tube, since the
supporting
plate displaces relative to the outer tube, deformation or the like of the
supporting plate
does not occur and an interval between the outer peripheral face of the inner
tube and
the inner peripheral face of the outer tube can be maintained.
[0019]
In the present invention, a configuration is preferably adopted in which a
second hole part for ejecting combustion gases is provided at a position
separated from
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the stagnation point in the inner tube.
In this manner, in the present invention, propagation of a flame, that is
formed
and retained at a stagnation point, is enable into the combustion gas ejected
from the
second hole part. Consequently, in the present invention, the pressure loss
resulting
from use of a porous body can be avoided. Furthermore since the introduced
amount
of heat can be increased without increasing the length of the inner tube and
the outer
tube, it is possible to prevent an increase in the size of the device
resulting for example
from increasing the length of the inner tube and outer tube. In the present
invention,
since pressure loss can be suppressed, application is possible to low-pressure
city gas
lines.
[0020]
The second hole part preferably adopts a configuration in which the second
hole part is disposed on both sides sandwiching the first region or is
disposed alternately
with the hole part along the first region, or a configuration in which the
second hole part
is disposed on both sides sandwiching a region facing the stagnation point
formation
member and is disposed alternately with the hole part along the facing region.
In this manner, the present invention enables formation and maintenance of a
flame and equal distribution of flame propagation of the flame.
[0021]
Furthermore the present invention preferably adopts a configuration in which
the supply passage in the inner tube is closed at the distal end.
In this manner, the present invention provides a small low-cost combustion
heater that supplies combustion gas from a base end and enables discharge of
exhaust
gases.
[Effects of the Invention]
[0022]
According to the combustion heater of the present invention, excessive
temperature increase in the inner tube is suppressed and heating efficiency
can be
improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023]
FIG IA is a front sectional view of a combustion heater 1 according to a first
embodiment.
FIG. 1B is a side sectional view of a combustion heater I according to a first
embodiment.
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FIG 2A is a plan view of the inner tube seen from a first region side.
FIG 2B is side sectional view of a combustion heater including an inner tube.
FIG 3A is a front sectional view of a combustion heater 1 according to a third
embodiment.
FIG 3B is a side sectional view of the combustion heater according to the
third
embodiment.
FIG 4 is a detailed view of the principal components of a combustion heater
according to a fourth embodiment.
FIG. 5 is a pattern diagram of an outer tube and inner tube according to a
fifth
embodiment.
FIG. 6A is a front sectional view of a combustion heater according to a sixth
embodiment.
FIG 6B is a side sectional view of the combustion heater according to the
sixth
embodiment.
FIG. 6C is an enlarged view of the principal components of the combustion
heater according to the sixth embodiment.
FIG 7A is a front sectional view of a combustion heater according to a seventh
embodiment.
FIG. 7B is a side sectional view of the combustion heater according to the
seventh embodiment.
FIG. 7C is an enlarged view of the principal components of the combustion
heater according to the seventh embodiment.
FIG. 7D is an enlarged view of the principal components of the combustion
heater according to the seventh embodiment.
FIG 8A is a front sectional view of a combustion heater according to an eighth
embodiment.
FIG 8B is a side sectional view of the combustion heater according to the
eighth embodiment.
FIG 8C is an enlarged view of the principal components of the combustion
heater according to the eighth embodiment.
FIG 9 is a detailed view of the principal components of a combustion heater
disposing the inner tube and the outer tube in a concentric orientation.
BEST MODES FOR CARRYING OUT THE INVENTION
[0024]
The aspects of the embodiments of a combustion heater according to the
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present invention will be described below making reference to FIG. 1 to FIG 8.
Since
each figure used in the description below depicts each member with a size
enabling
recognition thereof, suitable modification may be made to the dimensions of
each
member.
[0025]
(First Embodiment)
FIG. IA is a front sectional view of a combustion heater 1 according to a
first
embodiment and FIG 1 B is a side sectional view.
The combustion heater 1 schematically includes an outer tube 10 acting as a
radiation tube made from a heat-resistant metal and closed at a distal end,
and a
heat-resistant metal inner tube 20 cantilever-supported by a support means
(not shown)
at a base end (left side of FIG 1A), disposed in an inner portion of the outer
tube 10
and having a supply passage 21 for combustion gas G in an inner portion.
[0026]
A combustion gas G includes a premixed gas of fuel and air or a premixed gas
of fuel and an oxygen-containing gas. The fuel includes methane, propane or
the like.
Furthermore a liquid fuel may be used by providing a position for
prevaporization.
[0027]
The outer tube 10 has a round cylindrical shape with a bottom closed at a
distal
end and is connected at the base end with a discharge tube 11 which discharges
combusted gas. A radiation promotion layer (radiation promotion surface) 10B
for
promoting radiation is formed on the inner peripheral face IOA of the outer
tube 10.
The radiation promotion layer l OB will be described below.
[0028]
The inner tube 20 has a round cylindrical shape with a bottom closed at a
distal
end in the same manner as the outer tube 10 and is connected at the base end
with a
premixed gas supply mechanism (not shown) for supplying the combustion gas G
above.
For example, the whole premixed gas may be supplied with an air excess ratio
of 1.0 -
1.6.
The inner tube 20 is disposed eccentrically on an inner side of the outer tube
10
near the distal end to thereby form a combustion space 30 between the outer
peripheral
face 20A and the inner peripheral face I OA of the outer tube 10. A radiation
promotion
layer (radiation promotion surface) 20B is formed in the same manner as the
radiation
promotion layer 10B above on the outer peripheral surface 20A facing the
combustion
space 30 of the inner tube 20.
[0029]
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The radiation promotion layers IOB, 20B are formed by a coated layer coated
by thermal-spraying onto an inner peripheral surface 1OA or outer peripheral
surface
20A using a ceramic binder for example. The coated layer uses a material which
is
heat resistant to a temperature of approximately 800 C. Furthermore high
adhesion
and durability can be enabled by using thermal spraying to form the radiation
promotion
layers IOB, 20B.
[0030]
The outer peripheral surface 20A of the inner tube 20 has a first region 22 at
which a distance to the inner peripheral surface IOA of the outer tube 10 is
shortest, and
a second region 23 at which the distance is longer than the first region 22.
More
specifically, on the outer peripheral surface 20A, the first region (bus line)
22 which has
the shortest distance to the inner peripheral surface of 1OA of the outer tube
10 is
formed in an axial direction in an eccentric orientation in the inner tube 20
(in FIG 1,
refer to lower section of FIG 1B), and in other regions, the second region 23
is formed
which has a longer distance to the inner peripheral surface IOA than the first
region 22.
[0031]
In the first region 22, a plurality of hole parts 24 (five in this example)
spaced
at an interval along the first region 22 and positioned on the distal end of
the inner tube
20 pierce the tube wall along an axial direction. An ignition apparatus (not
shown) is
provided in proximity to a position facing the hole parts 24 of the outer tube
10.
The outer peripheral surface 20A disposed further towards the base end (left
side of FIG IA) than the region forming the hole parts 24 is a preheating
region P for
preheating the combustion gas G of the supply passage 21 using combusted gases
(flame).
[0032]
Next, the combustion operation in the combustion heater I will be described.
Combustion gas G supplied from the premix gas supply mechanism to the
supply passage 21 of the inner tube 20 is ejected from the hole part 24
towards the inner
peripheral surface 1 OA of the outer tube 10.
Since the hole part is provided to the first region 22 at which a distance to
the
inner peripheral surface 1OA of the outer tube 10, combustion gas G which is
ejected
from the hole part 24 collides with the inner peripheral surface I OA of the
outer tube 10,
forms a stagnation point S on the inner peripheral surface 1OA corresponding
to each
hole part 24, and is branched distribution along the inner peripheral surface
I OA at each
stagnation point S.
[0033]
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An ignition apparatus ignites the combustion gas G in proximity to a
stagnation
point S to thereby form a flame. The combustion gas G branching at a
stagnation point
S flows from the proximity to the first region 22 which has a small sectional
area into
the combustion space which is on the opposite side to the first region 22 and
has a large
sectional area. Further, as shown in FIG 1 B, a flame F is formed on both
sides of the
inner tube 20 of the combustion space 30.
Since the flow speed of the gas at the stagnation point S is zero at this
time, a
resulting flame is stably retained as a result of the circulating flow formed
in proximity
to the jet towards the stagnation point S.
[0034]
The combustion gas flows through the combustion space 30 and is discharged
from a discharge tube 11. However heat exchange with the combustion gas
(uncombusted gas) G occurs with the tube wall of the inner tube 20 in the
preheating
region P of the inner tube 20 in the section from the combustion space 30 to
the
discharge tube 11.
In this manner, the combustion gas G in the supply passage 21 is ejected from
the hole part 24 in a high-temperature pre-heated state and thereby increases
the
stability of the flame F. Thus even when the gas G is ejected into the
confined
combustion space 30, uncombusted components are not produced and stable
combustion is enabled.
[0035]
Although the inner tube 20 in particular reaches a high temperature as a
result
of the heat of the combustion gas and the heat of the flame F, since the
radiation
promotion layer 20B is provided on the outer peripheral surface 20A of the
inner tube
20, emission of heat (radiation) of radiant heat is promoted by increasing the
thermal
emissivity of the inner tube 20. On the other hand, since the radiation
promotion layer
10B is also provided on the inner peripheral surface 10A of the outer tube 10,
absorption of radiant heat from the flame F and radiant heat from the inner
tube 20 is
promoted.
[0036]
In the aspects of the present embodiments as described above, emission of heat
from the inner tube 20 as radiant heat is promoted by the radiation promotion
layer 20B
of the inner tube 20. Consequently excessive temperature increase of the inner
tube 20
can be suppressed and a large part of the heat in the inner tube 20 can be
used for
heating (preheating) of the combustion gas G in an inner section since the
radiation
capacity falls even at a low temperature thereby a heating characteristic is
maintained.
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Consequently, a preheating temperature for the combustion gas G can be
regulated by
regulating the structure (material, thickness, distribution and the like) of
the radiation
promotion layer 20B.
[0037]
The radiant heat enables heating of the outer tube 10 and improves the heating
efficiency through the outer tube 10. In particular, in the present
embodiment, since
the radiation promotion layer IOB is also provided on the inner peripheral
surface 1 OA
of the outer tube 10, the heat of the combustion space 30 is effectively
absorbed by the
outer tube 10 and the heating efficiency through the outer tube 10 is further
improved.
In the present embodiment, since combustion gas G is ejected from the hole
part 24 formed on the tube wall of the inner tube 20 and the flame F is
retained at the
stagnation point S, cost increases caused by provision of a porous tube can be
avoided
and formation of a stable flame can be facilitated even when varying a flow
amount.
In addition, in the present embodiment, merely increasing the number of holes
24
enables an increase in the combustion amount. Thus manufacturing costs for the
combustion heater 1 can be suppressed by use of few components and a simple
structure.
There is no need to considerably increase the supply pressure of the
combustion gas G
such as when using a porous tube, and application to low-pressure city gas
lines is
sufficiently enabled. Furthermore in the present embodiment, a stable flame F
can be
formed and retained in a simple manner and at a low cost by forming the outer
peripheral surface 20A of the inner tube 20 and the first region 22 which has
a short
distance to the inner peripheral surface 1OA of the outer tube 10 with a
simple
configuration in which the inner tube 20 is disposed eccentrically with
respect to the
outer tube 10.
[0038]
When a porous tube is used and the supply pressure of gas is increased, there
is
the possibility that the flame extends to the outer tube and will not be
maintained, and
that the discharge route for combusted gas will not be retained. However in
the
present embodiment, a sufficient discharge route is retained in the combustion
space 30
facing the region (second region) opposite to the first region 22.
[0039]
In the present embodiment, since a stagnation point S is formed on an inner
peripheral face IOA of the outer tube 10 and the flame F is maintained along
the inner
peripheral surface 10A, extraction of heat is not impeded such as when a tube-
shaped
flame is separated from the outer tube 10, and heating efficiency through the
outer tube
is improved.
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[0040]
(Second Embodiment)
Next, a second embodiment of the combustion heater 1 will be described
making reference to FIG 2.
In the figure, those components which are the same as the components of the
first embodiment shown in FIG 1 are denoted by the same reference numerals and
description thereof will not be repeated.
The point of difference of the second embodiment from the first embodiment is
that a second hole part for reducing gas pressure loss is provided separately
to the hole
part 24.
[0041]
FIG 2A is a plan view of the inner tube 20 seen from the first region 22 and
FIG. 2B is side sectional view of the combustion heater 1 including the inner
tube 20.
As shown in FIG 2A, in the tube wall of the inner tube 20, a hole part 24 is
provided in the first region 22 and in addition a second hole part 25 is
provided
alternating with the hole part 24 along the first region 22 on both sides
sandwiching the
first region 22.
As shown in FIG 2B, combustion gas G is ejected from the second hole part 25
towards a position separated from the stagnation point S.
The second hole part 25 is provided at a position of stable propagation of a
flame F formed at the stagnation point S in combustion gas G ejected from the
second
hole part 25.
In other respects, the configuration is the same as the first embodiment and
includes that the radiation promotion layer 20B is provided on the outer
peripheral
surface 20A of the inner tube 20 and that the radiation promotion layer l OB
is provided
on the inner peripheral surface IOA of the outer tube 10.
[0042]
In the combustion heater 1 having the above configuration, the same operation
and effect as the first embodiment is obtained and a flame F which is formed
and
maintained at a stagnation point S can be propagated in combustion gas G
ejected
expelled from the second hole part 25 to thereby facilitate of combustion gas
under an
increased flow rate. As a result, in the present embodiment, pressure loss
caused for
example by use of a porous body can be avoided. Furthermore the introduced
amount
of heat can be increased without increasing the length of the inner tube and
the outer
tube to increase the flow amount. As a result, it is possible to prevent an
increase in
the size of the device resulting for example from increasing the length of the
inner tube
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20 and outer tube 10. In the present invention, since pressure loss can be
suppressed,
application is possible to low-pressure city gas lines.
In the present embodiment, since the hole part 24 and the second hole part 25
are disposed alternately along the first region 22, and the second hole part
25 is
disposed on both sides sandwiching the first region 22, formation and
maintenance of a
flame F and flame propagation are produced in a stable state with an
substantially equal
distribution.
[0043]
(Third Embodiment)
Next, a third embodiment of the combustion heater 1 will be described making
reference to FIG 3.
In the figure, those components which are the same as the components of the
first embodiment shown in FIG. 1 are denoted by the same reference numerals
and
description thereof will not be repeated.
The point of difference of the third embodiment from the first embodiment
resides in the provision of a supporting plate on the distal end of the inner
tube 20.
[0044]
As shown in FIG 3A, a supporting plate (supporting member) 40 formed from
a heat-resistant metal or the like in a direction which is orthogonal to the
axial direction
is provided further towards a distal end than the hole part 24 of the inner
tube 20. As
shown in FIG. 3B, the supporting plate 40 is engaged and fixed to the outer
peripheral
surface 20A of the inner tube 20 by a through hole 40A and is supported to
freely
displace in an axial direction on the inner peripheral face 1 OA of the outer
tube 10 by an
outer peripheral surface 40B.
That is to say, the supporting plate 40 is integrally formed with the inner
tube
20 to have a dimension which enables closure of the whole combustion space 30
and is
provided to freely displace in an axial direction with reference to the outer
tube 10.
In other respects, the configuration is the same as the first embodiment and
includes the provision of the radiation promotion layer 20B on the outer
peripheral
surface 20A of the inner tube 20 and the provision of the radiation promotion
layer 1 OB
on the inner peripheral surface 1 OA of the outer tube 10 (however in the
partial enlarged
view shown in FIG 3A and in FIG. 3B, the radiation promotion layers IOB, 20B
are
omitted).
[0045]
In the combustion heater 1 having the above configuration, the same operation
and effect as the first embodiment is obtained, and since distal end side of
the inner tube
14
CA 02713306 2010-07-26
20 which is cantilever supported on a base end side is supported by the
supporting plate
40, a fixed interval can be maintained between the outer peripheral surface
20A of the
inner tube 20 (that is to say, the first region 22) and the inner peripheral
surface 1 OA of
the outer tube 10. Furthermore even when the high-temperature inner tube 20
undergoes thermal expansion by reason of a temperature difference between the
outer
tube 10 and the inner tube 20, deformation or bending can be prevented since
the
supporting plate 40 which is integrally formed with the inner tube 20 can
displace in an
axial direction relative to the inner peripheral surface l OA of the outer
tube 10.
[0046]
Combustion gas G which is ejected from the hole part 24 which is positioned
further towards a distal end side collides with the inner peripheral surface
10A of the
opposed outer tube 10, forms a stagnation point S on the inner peripheral
surface 1 OA at
each hole part 24, and branches along the inner peripheral surface IOA at the
stagnation
point S. However since the combustion space 30 which is opposed to the first
region
22 is closed by the supporting plate 40, combustion gas G which is branched
towards
the supporting plate 40 collides with the supporting plate 40 and then is
introduced into
the combustion space 30 facing the opposite side (second region 23) to the
first region
22. Consequently, ignition of the peripheral combustion gas G is facilitated
by a flame
which is retained at the stagnation point S.
[0047]
Further, in the present embodiment, since the combustion space 30 is
partitioned by the supporting plate 40, it is possible to avoid a situation in
which the
combustion gas G accumulates in an uncombusted state in the distal end portion
of the
outer tube 10 which has a relatively low temperature and results in production
of CO.
In the above embodiment, although the supporting member is configured as a
tabular supporting plate 40, the invention is not limited in this respect, and
for example,
it may employ a supporting member which includes a ring member supported to
freely
displace in an axial direction on the inner peripheral surface 10A of the
outer tube 10
and a rod member which connects the ring member and the inner tube 20.
[0048]
(Fourth Embodiment)
Next, a fourth embodiment which is a modification of the third embodiment
above will be described making reference to FIG 4.
In the figure, those components which are the same as the components of the
third embodiment shown in FIG 3 are denoted by the same reference numerals and
description thereof will not be repeated.
CA 02713306 2010-07-26
[0049]
As shown in FIG. 4, in the present embodiment, a supporting plate 41 is
respectively provided on the outer peripheral surface 20A of the outer tube 20
on both
sides in the direction of alignment of the hole parts 24 to sandwich the
stagnation point
S which corresponds to the hole part 24, and is further towards the base end
side than
the supporting plate 40. The supporting plate 41 has a dimension which closes
the
combustion space 30 facing the first region 22. More specifically, each
supporting
plate 41 does not close the whole of the combustion space 30 like the
supporting plate
40, but covers only the combustion space 30 in proximity to the first region
22 so that
combustion gas G ejected from the hole part 24 can flow into the combustion
space 30
on the opposite side, and be discharged from the discharge tube 11.
Furthermore each
supporting plate 41 protrudes from the tube wall of the inner tube 20 towards
the outer
tube 10 only on the periphery of the first region 22 so that the position of
the inner tube
20 is maintained with respect to the outer tube 10, and is formed in a fan
shape for
example supported on the inner peripheral surface 1 OA.
In other respects, the configuration is the same as the third embodiment and
includes the provision of the radiation promotion layer 20B on the outer
peripheral
surface 20A of the inner tube 20 and the provision of the radiation promotion
layer I OB
on the inner peripheral surface 1OA of the outer tube 10.
[0050]
In the combustion heater I having the above configuration, the same operation
and effect as the third embodiment is obtained, and combustion gas G ejected
from each
hole part 24 collides with the supporting plate 41 and then is introduced into
the
combustion space 30 facing the opposite side (second region 23) to the first
region 22.
Consequently, more effective ignition of the peripheral combustion gas G is
facilitated
by a flame which is retained at the stagnation point S.
[0051]
(Fifth Embodiment)
Next, a fifth embodiment of the combustion heater 1 will be described making
reference to FIG 5.
FIG 5 is a schematic view of an outer tube 10 and inner tube 20 according to a
fifth embodiment.
As shown in the figure, an inner tube 20 in the combustion heater 1 according
to the present embodiment is provided at an interval in a peripheral direction
about the
central axis of the outer tube 10 in the combustion space 30 in the outer tube
10. The
plurality of inner tubes 20 (in FIG 5, six are provided at an interval of 60
) is
16
CA 02713306 2010-07-26
respectively disposed in an eccentric orientation to the outer tube 10.
Furthermore in each inner tube 20, a plurality of hole parts 24 (not shown in
FIG. 5) is formed at an interval in an axial direction and is positioned in
the first region
22 at which the distance between the outer peripheral surface 20A and the
inner
peripheral surface 1 OA of the outer tube 10 is shortest.
In other respects, the configuration is the same as the first embodiment and
includes the provision of the radiation promotion layer 20B on the outer
peripheral
surface 20A of the inner tube 20 and the provision of the radiation promotion
layer 1 OB
on the inner peripheral surface l OA of the outer tube 10.
[0052]
In the combustion heater 1 having the above configuration, combustion gas G
is respectively ejected from (the hole parts of) the plurality of inner tubes
20 and a
stagnation point is formed on the inner peripheral surface 1OA of the outer
tube 10 to
thereby form a stable plurality of flames about the axis along the inner
peripheral
surface of the outer tube 10 by ignition of the combustion gas G.
Therefore in addition to obtaining the same operation and effect as the first
embodiment, the present embodiment enables heating of the outer tube 10 to a
higher
temperature.
[0053]
(Sixth Embodiment)
Next, a sixth embodiment of the combustion heater I will be described making
reference to FIG 6.
In the figure, those components which are the same as the components of the
first embodiment shown in FIG 1 are denoted by the same reference numerals and
description thereof will not be repeated.
Although all of the first to the fifth embodiments were configured by
formation
of a stagnation point S on the inner peripheral face IOA of the outer tube 10,
the sixth
embodiment will describe formation on the surface of a bluff body (stagnation
point and
circulating flow formation member).
[0054]
As shown in FIG. 6A, the combustion heater 1 according to the present
embodiment includes a plurality of inner tubes 20 and a bluff body (stagnation
point and
circulating flow formation member) 50 that are formed from a heat-resistant
metal, that
are cantilever supported by a supporting member (not shown) at a base end (the
left end
of FIG. 6A) in the combustion space 30 of the outer tube 10 and that is
provided with a
supply passage 21 for combustion gas G therein.
17
CA 02713306 2010-07-26
[0055]
As shown in FIG 6B, a plurality of inner tubes 20 is disposed at an interval
about the central axis of the outer tube 10 (in FIG 6, six are provided at an
interval of
60').
Each inner tube 20 includes a plurality of hole parts 24 (five in the figure)
radially provided in the tube wall at intervals along an axial direction at a
position
facing the bluff body 50 at the distal end and oriented towards the central
axis of the
outer tube 10.
[0056]
The axial line of the bluff body 50 is aligned with the central axis of the
outer
tube 10 and the circumference thereof is surrounded by inner tubes 20. A
concave
curve 50A formed about the axis of the inner tube 20 is formed in an axial
direction at a
position facing each inner tube 20 (hole part 24).
In other respects, the configuration including the provision of the radiation
promotion layer 20B on the outer peripheral surface 20A of the inner tube 20
and the
provision of the radiation promotion layer 10B on the inner peripheral surface
IOA of
the outer tube 10 (however in FIG 6B and in FIG. 6C, the radiation promotion
layers
l OB, 20B are omitted) is the same as the first embodiment.
[0057]
In the combustion heater 1 having the above configuration, as shown in FIG
6C, combustion gas G supplied to the supply passage 21 of the inner tube 20 is
ejected
from the respective hole parts 24 towards the concave curve 50A of the bluff
body 50.
The combustion gas G ejected from the hole parts 24 collides with the facing
concave curve 50A of the bluff body 50 and forms a stagnation point S on the
concave
curve 50A at each hole part 24 and branches along the concave curve 50A at the
stagnation point S.
[0058]
An ignition apparatus ignites the combustion gas G in proximity to the
stagnation points S to thereby a flame is formed and maintained at the
stagnation point
S. Since the flow speed of the gas at the stagnation point S at this time is
approximately zero, the flame formed by circular flow in the periphery of the
jet
towards stagnation point S is stably maintained at the stagnation point S.
The combustion gas G which has branched at the stagnation point S flows from
the proximity of the bluff body 50 which has a high gas pressure into the
combustion
space 30 of the inner peripheral surface 1OA side of the outer tube 10 which
is the
opposite side to the bluff body 50 with respect to the inner tube 20.
18
CA 02713306 2010-07-26
[0059]
The combustion gas flows into the combustion space 30 and is discharged from
the discharge tube 11. Heat exchange with the combustion gas (uncombusted gas)
G is
performed via the tube wall of the inner tube 20 in the preheating region P of
the inner
tube 20 midway from the combustion space 30 to the discharge tube 11.
In this manner, combustion gas G in the supply passage 21 which is preheated
to a high temperature is ejected from the hole part 24 in being preheated to a
high
temperature thereby increase the stability of the flame F. Therefore even when
ejected
into the confined combustion space 30, uncombusted components are not produced
and
stable combustion is enabled.
[0060]
In the present embodiment as described above, since combustion gas G is
ejected from the hole part 24 formed in the tube wall of the inner tube 20
towards the
concave curved 50A of the bluff body 50 and retains a flame F at the
stagnation point S,
cost increases for example caused by provision of a porous tube can be avoided
and
formation and retention of a stable flame F are facilitated even when varying
the flow
amount. In addition, in the present embodiment, merely increasing the number
of hole
parts 24 to increase of the combustion amount. Thus manufacturing costs for
the
combustion heater 1 can be suppressed by use of fewer components and a simple
structure. Further, there is no requirement for considerably increase of the
supply
pressure of the combustion gas G in contrast to use of a porous tube, and
therefore
application to low-pressure city gas lines is sufficiently enabled.
Furthermore, since the radiation promotion layer 20B is provided on the outer
peripheral surface 20A of each inner tube 20 and the radiation promotion layer
l OB is
also provided on the inner peripheral surface 1OA of the outer tube 10, the
heat of the
combustion space 30 can be effectively absorbed by the outer tube 10, and
heating
efficiency is further improved via the outer tube 10.
[0061]
(Seventh Embodiment)
Next, a seventh embodiment of the combustion heater 1 will be described
making reference to FIG. 7.
In the figure, those components which are the same as the components of the
sixth embodiment shown in the figure are denoted by the same reference
numerals and
description thereof will not be repeated.
The different point of difference between the seventh embodiment and the sixth
embodiment resides in the fact that a circular tube which is the same as the
inner tube
19
CA 02713306 2010-07-26
20 is disposed on the central axis of the outer tube 10.
[0062]
In other words, as shown by the partial enlarged view in FIG 7C, in the
present
embodiment, an inner tube (stagnation point formation member) 120 is axially
aligned
with central axis of the outer tube 10 and disposed with an interval with
respect to the
inner tube 20. The inner tube 120 is a round cylinder and is provided with a
bottom by
closure of a distal end. A premix gas supply mechanism (not shown) for
supplying
combustion gas G to the supply passage 121 in an inner portion is connected to
the base
end of the inner tube 20. A radiation promotion layer 120B which is similar to
the
radiation promotion layer 20B is provided on the outer peripheral surface 120A
of the
inner tube 120.
[0063]
The inner tube 120 includes hole parts 124 for ejecting combustion gas G
respectively formed at a position facing each inner tube 20 disposed on a
circumference
thereof. As shown in FIG 7D, as to the axial orientation, the hole parts 124
are formed
at a position facing the outer peripheral surface 20A and do not face the hole
parts 24
for each inner tube 20. In other words, the hole parts 24 of the inner tube 20
also face
the outer peripheral surface 120A and do not face the hole parts 124 of the
inner tube
120.
In other respects, the configuration is the same as the sixth embodiment and
includes the provision of the radiation promotion layer 20B on the outer
peripheral
surface 20A of the inner tube 20 and the provision of the radiation promotion
layer l OB
on the inner peripheral surface 10A of the outer tube 10 (however in FIG 7B,
the
radiation promotion layers 10B, 20B, 120B are omitted).
[0064]
In the combustion heater 1 having the above configuration, combustion gas G
supplied from the premixed gas supply mechanism to the supply passage 21 of
the inner
tube 20 is ejected from the respective hole parts 24 towards the outer
peripheral surface
120A of the inner tube 120. A stagnation point S for combustion gas G is
formed on
the outer peripheral surface 120A. Combustion gas G branches at the stagnation
point
S and flows along the outer peripheral surface 120A.
[0065]
On the other hand, combustion gas G supplied to the supply passage 121 of the
inner tube 120 is ejected from the respective hole parts 124 towards the outer
peripheral
surface 20A of the inner tube 20. A stagnation point S for combustion gas G is
formed
on the outer peripheral surface 20A, and combustion gas G branches at the
stagnation
CA 02713306 2010-07-26
point S and flows along the outer peripheral surface 20A. In other words, in
the
present embodiment, in addition to the inner tube 120, the inner tube 20 also
operates as
a stagnation point formation member.
[0066]
Ignition of the combustion gas G in proximity to the stagnation point S
enables
formation and retention of a flame at the stagnation point S. Since the flow
speed of
the gas at the stagnation point S at this time is zero, a resulting flame is
stably retained
at the stagnation point S.
The combustion gas G branching at the stagnation point S flows into the
combustion space 30 on the inner peripheral surface I OA of the outer tube 10
which has
a relatively low gas pressure. The combusted gas is discharged from the
discharge
tube 11.
[0067]
In the above embodiment, in addition to obtaining the same operation and
effect as the sixth embodiment, since combustion gas G is also ejected from
the inner
tube 120, more effective heating is enabled. Furthermore since a stagnation
point S is
also formed on the outer peripheral surface 20A of the inner tube 20 which is
disposed
on a circumference thereof and thereby forms and retains a flame, a stable
flame can be
formed and retained over a wide range.
The hole part 24 of the inner tube 20 and the hole part 124 of the inner tube
120 may be provided at a mutually opposed position. However provision is
preferred
at a mutually facing position on the outer peripheral surface 120A, 20A in
order to form
a more stable stagnation point S.
[0068]
(Eighth Embodiment)
Next, an eighth embodiment of the combustion heater 1 will be described
making reference to FIG 8.
In the figure, those components which are the same as the components of the
sixth embodiment shown in FIG. 6 are denoted by the same reference numerals
and
description thereof will not be repeated.
[0069]
As shown in FIG. 8B, in a present embodiment, a plurality of inner tubes 20 is
mutually disposed at an interval in a peripheral direction about the central
axis (in the
figure, six are provided at an interval of 60 ) without providing an inner
tube on the
central axis of the outer tube 10.
As shown by the partial enlarged view in FIG 8C, each inner tube 20 includes
21
CA 02713306 2010-07-26
respective hole parts 24 ejecting combustion gas G to a position facing the
adjacent
inner tube 20.
In the same manner as the seventh embodiment as shown above by the partially
enlarged view in FIG 7D, a position of the axial direction of the hole parts
24 is
preferably positioned alternately for adjacent inner tubes 20 so that ejected
combustion
gas G collides with an outer peripheral surface 20A of the adjacent inner tube
20.
In other respects, the configuration is the same as the sixth embodiment and
includes the provision of the radiation promotion layer 20B on the outer
peripheral
surface 20A of the inner tube 20 and the provision of the radiation promotion
layer l OB
on the inner peripheral surface 1OA of the outer tube 10 (however in FIG 8B,
the
radiation promotion layers l OB, 20B are omitted).
[0070]
In the combustion heater 1 having the above configuration, in addition to
obtaining the same operation and effect as the sixth embodiment, since a
stagnation
point S and a flame are formed at a more proximate position to the outer tube
10 that
acts as a heat radiation tube, heat extraction via the outer tube 10 is
facilitated and
heating efficiency can be improved.
[0071]
Although the preferred embodiments of the present invention have been
described above making reference to the attached figures, it is obvious that
the present
invention is not limited to the examples. The configuration or assembly of
each
constituent member described in the examples above are merely exemplary and
various
modifications are possible resulting from design requirements or the like
within a scope
which does not depart from the spirit of the present invention.
[0072]
For example, in the second embodiment, although a configuration was
described in which a second hole part 25 was provided in addition to the hole
part 24,
the invention is not limited in this respect, and a configuration of the inner
tube 20 is
possible with respect to the third to the eighth embodiments in which a second
hole part
25 is provided in addition to the hole part 24.
In the same manner, in the third embodiment, although a supporting plate 40
was provided on a distal end of the inner tube 20, the same operation and
effect as the
third embodiment may be enabled in the fourth to the eighth embodiments by a
configuration in which a supporting plate is provided on the distal end.
[0073]
In the embodiments above, a configuration was adopted in which a first region
22
CA 02713306 2010-07-26
22 having the shortest distance between the outer peripheral surface 20A and
the inner
peripheral surface IOA of the outer tube 10 was formed by disposing each inner
tube 20
in an eccentric orientation to the outer tube 10. However the invention is not
limited in
this regard and a concentric orientation is also possible.
[0074]
In the embodiments above, although a configuration was described in which a
radiation promotion layer was provided on both of the inner peripheral surface
1OA of
the outer tube 10 and the outer peripheral surface 20A of the inner tube 20,
the invention
is not limited in this regard and the radiation promotion layer may be
provided only on
the outer peripheral surface 20A of the inner tube 20.
In the embodiments above, a configuration was described in which the
radiation promoting surface was formed by the radiation promotion layers IOB,
20B
(120B). However in addition, the outer tube 10 and the inner tube 20, 120 may
be
configured by the material that forms the radiation promotion layers 10B, 20B,
120B
and the inner peripheral surface 1OA and the outer peripheral surface 20A,
120A may
themselves include a radiation promotion characteristic.
[0075]
In the embodiments above, a configuration was adopted in which the each
inner tube 20 was disposed eccentrically with respect to the outer tube 10.
However
the invention is not limited in this respect and for example, as shown in FIG
9, the inner
tube 20 that includes a hole part 24 disposed in a radial fashion and includes
a radiation
promotion layer 20B may be disposed concentrically to the outer tube 10 which
has the
radiation promotion layer l OB.
[Industrial Applicability]
[0076]
As described above, the combustion heater according to the present invention
enables suppression of excessive temperature increase in an inner tube and
improves
heating efficiency.
23
