JPH0512565Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a gas combustion device that can be advantageously used in industrial furnaces and the like.

BACKGROUND ART Traditionally, gas combustion devices used in industrial furnaces, etc. have been using immersion tubes that are immersed in the liquid to be heated and used for heating the liquid, or heating radiator tubes that emit direct radiant heat from the radiator tubes. There is a radiant tube that heats the object to be heated, but it is difficult to achieve uniform gas combustion throughout the long radiator tube, and it is recommended to use a radiant tube with a small diameter to avoid local overheating. I couldn't do it.

In order to solve this problem, a combustion device is used in which a combustion catalyst is installed inside a small-diameter heat dissipation tube, and the object to be heated is heated by catalytic combustion of a combustible mixed gas. It is extremely effective in downsizing the entire device because it allows for a smaller diameter, is easy to assemble, and can be installed in a narrow space. However, in such a structure in which a combustion catalyst is provided within the heat dissipation tube, combustion tends to concentrate on the first stage catalyst, and therefore it is not possible to obtain a uniform temperature distribution on the surface of the heat dissipation tube. In addition, in order to avoid an abnormal rise in catalyst temperature, it is necessary to keep the air ratio of the mixed gas fed high and the theoretical flame temperature low, for example, at least 22 volumes of air per 1 volume of natural gas. Since a large amount of air is sent in compared to the required air capacity, exhaust loss is large, and the blower power required to send the large amount of air is large, which reduces operating efficiency and increases production costs. ing.

Therefore, in order to obtain a uniform temperature distribution over the entire heat dissipation tube, a combustion catalyst is supported directly on the inner peripheral surface of the heat dissipation tube, and a passage for the combustible mixed gas is formed inside the tube, thereby preventing abnormal rise in catalyst temperature. A configuration that avoids this is disclosed in patent application publication No. 59-501518.

Problems to be Solved by the Invention In the above-mentioned prior art disclosed in Patent Application Publication No. 59-501518, it is difficult to support the catalyst directly on the inner circumferential surface of the heat dissipation tube, which complicates the manufacturing process.
In addition, since the catalyst is directly affected by cooling outside the heat sink, it is difficult to control catalytic combustion, and therefore its use is limited to relatively stable temperatures outside the heat sink. will be subject to restrictions.

The purpose of this invention is to solve the above technical problems,
It is an object of the present invention to provide a gas combustion device that is easy to manufacture and can provide a uniform temperature distribution on the surface of a heat sink.

Means for Solving the Problems The present invention constitutes an air chamber and has an opening 4a in the end wall.
A blower 7 that supplies combustion air to the air chamber of the casing 4; A pilot burner 11 that is provided in the casing 4 and heats the combustion air in the casing 4; A heat dissipation tube 5 having a base end 5a to be connected, and a distal end 3a that enters the base end 5a of the heat dissipation tube 5, and between the outer circumferential surface of the distal end 3a and the inner circumferential surface of the proximal end 5a. a fuel supply pipe 3 having a gap 44 and passing through the casing 4 and supplying fuel gas made of natural gas; and a plurality of catalysts arranged at intervals in the axial direction of the heat dissipation pipe 5. Among the members A1 to A3, each catalyst member A1 to A3 is disposed coaxially within the heat dissipation tube 5 and contacts the inner circumferential surface of the heat dissipation tube 5, at least in the vicinity of the peripheral portion 26 close to the wall surface of the heat dissipation tube 5. A large number of through holes 20 are formed extending in the tube axis direction, and a flow area 2 is formed near the center of the tube axis.
3 and 27 are formed extending in the tube axis direction.
1, the outer diameter D ₁ of the base body 21 and the flow area 23,
The ratio D ₁ /D ₂ to the inner diameter D ₂ of 27 is selected to be approximately 1.2, and the base 21 has a cordierite honeycomb structure.
Activated alumina coated on the inner peripheral surface of the through hole 20 near the peripheral portion 26 of the base body 21; A catalyst 22 made of platinum or palladium and supported on the activated alumina, the catalyst being a catalyst for activated alumina. Such catalyst members A1 to A3 including a catalyst 22 with a ratio of about 0.5 to 3%, and a catalyst member A provided in the heat dissipation pipe 5 as a final stage.
4, this final stage catalyst member A4 is disposed coaxially within the heat dissipation tube 5, is formed with a large number of through holes uniformly distributed in the tube axis direction over the entire cross section, and is made of cordierite. The base body 21 has a high quality honeycomb structure, activated alumina is coated on the inner circumferential surface of all the through holes in the base body 21, and platinum or palladium is supported on the activated alumina and completely removes unburned gas from the combustion exhaust gas. Such a catalyst member A comprising a catalyst 22 to be combusted.
4. This is a gas combustion device characterized by comprising:

Effect According to the present invention, a plurality of through holes extending in the tube axis direction of the heat dissipation tube are formed at least near the inner peripheral surface of the heat dissipation tube, and a catalyst is supported in the through holes near the inner peripheral surface of the heat dissipation tube. catalyst members having a honeycomb structure are arranged in a heat radiation tube at intervals in the tube axis direction, a combustible mixed gas is passed through the heat radiation tube, and the flammable mixed gas is catalytically combusted by the catalyst member. By doing so, the combustion temperature of the catalyst member can be averaged, thereby making it possible to obtain as uniform a surface temperature distribution as possible over the entire heat dissipation tube. Furthermore, the manufacturing process of the heat dissipation tube is also simplified.

Embodiment FIG. 1 is a sectional view of an embodiment of the present invention.
Fuel gas of natural gas, which is city gas, is supplied from a pipe line 1 to a fuel supply pipe 3 via a solenoid valve 2.
The fuel supply pipe 3 is connected to a casing 4 that constitutes an air chamber.
The distal end portion 3a thereof is disposed facing the mixing chamber within the base end portion 5a of the heat dissipation tube 5. An opening 4a is provided in the left end wall of the casing 4 in FIG.
is formed. A gap 44 exists between the outer peripheral surface of the distal end portion 3a of the fuel supply pipe 3 and the inner peripheral surface of the base end portion 5a of the heat dissipation tube 5.

Combustion air from the blower 7 is supplied into the casing 4 from a conduit 9 via a solenoid valve 8 . The combustion air supplied into the casing 4 is supplied under pressure to the mixing chamber 6 through the opening 4a, and is premixed with the fuel gas. This combustible mixed gas is supplied under pressure to a flow path 10 in a heat dissipation pipe 5 connected to the casing 4 . Note that the casing 4 is provided with a pilot burner 11.
1 can heat the combustion air supplied from the casing 4 through the mixing chamber 6 into the heat sink 5.

In the middle of the flow path 10 of the heat dissipation tube 5, a plurality of (four in this embodiment) catalyst members A1 to A4 are arranged at intervals in the tube axis direction. The combustible mixed gas premixed in the mixing chamber 6 is transferred to the catalyst members A1 to A4.
catalytic combustion is carried out sequentially at the tip 5 of the heat dissipation tube 5.
released from b. A temperature detection element 12 is provided between the tip 5b of the heat dissipation tube 5 and the final stage catalyst member A4.
is provided and functions to detect the temperature of the combustion exhaust gas from the catalyst member A4. The output from temperature detection element 12 is given to control circuit 13 via line l1. Control circuit 1
3 controls the opening and closing operations of the electromagnetic valves 2 and 8 through lines 12 and 13 in response to the output from the temperature detection element 12, thereby controlling each combustion of the catalyst members A1 to A4 as described later. Temperature is regulated.
Note that the heat dissipation tube 5 has an elbow 14 as shown in FIG.
.about.19 may be connected in a meandering manner.

3 is a cross-sectional view of the catalyst member A1, FIG. 4 is a cross-sectional view taken along the cutting plane line - in FIG. 3, and FIG. 5 is an enlarged perspective view of the section in FIG. 3. The catalyst member A1 includes a honeycomb-shaped base 21
and a catalyst 22. The base body 21 is formed into a cylindrical shape and is arranged near the inner circumferential surface of the heat dissipation tube 5 coaxially therewith. Further, a catalyst 22 is supported in the large number of through holes 20, and when the combustible mixed gas flows through the catalyst 22, catalytic combustion occurs. On the other hand, the cavity 23 is arranged near the center of the tube axis, and does not burn the combustible mixed gas flowing through it.

Referring to FIG. 4, the radial thickness d of the base body 21 is selected depending on the inner diameter and temperature of the heat dissipation tube 5, but even if the cooling conditions of the outer circumferential surface 5d of the heat dissipation tube 5 change, the catalyst remains normal. To continue the combustion, the substrate 21
It is preferable to set the ratio between the cross-sectional area S1 of the center cavity 23 and the cross-sectional area S2 of the central cavity 23 to satisfy the relationship expressed by the first equation.

S1/S2≒( _D1 ) ²⁻ ( _D2 ) ² /( _D2 ) ² ≒1/2
...(1) Here, D ₁ is the outer diameter of the base 21, and D ₂ is the inner diameter of the base 21. As is clear from the first equation,
The inner diameter D ₂ of the cavity 23 of the base body 21 is relatively larger than the outer diameter D ₁ of the base body 21, and in order to satisfy the first equation, D ₁ /D ₂ is selected to correspond to about 1.2.

The base body 21 has a cordierite honeycomb structure, and the inner peripheral surface of the through hole 20 is coated with activated alumina. Platinum or palladium is used as the catalyst 22, and is supported on activated alumina within the through holes 20. When the combustible mixed gas flows through the through hole 20, it contacts the catalyst 22 and catalytically burns it. When using natural gas as fuel, the ratio of catalyst 22 to activated alumina is approximately 0.5.
Optimum catalytic combustion can be obtained by supporting the catalyst at ~3%.

Since the base body 21 constituting the catalyst member A1 has a honeycomb structure and is roughly cylindrical, combustion heat near the outer circumferential surface 21a of the base body 21 during catalytic combustion is directly transmitted to the heat dissipation tube 5. The combustion heat inside the base body 21 is transmitted to the combustion exhaust gas and radiated from the heat radiation pipe 5.
The combustion heat near the inner peripheral surface 21b is radiated to the combustible mixed gas flowing inside the cavity 23. Therefore, overheating of the entire base 21 can be prevented. Further, by catalytically burning only a part of the combustible mixed gas and letting the remaining part flow through the cavity 23, abnormal overheating of the catalyst member A1 can be prevented as much as possible, and the catalyst member Enables supply of flammable mixed gas to A2 and A3.

The other catalyst members A2 and A3 have the same configuration as the catalyst member A1. Also, the final stage catalyst member A4
Unlike the catalyst members A1 to A3, the through holes 20 are uniformly distributed over the entire cross section of the base body 21, and the catalyst 22 is supported on the inner peripheral surface of all these through holes 20, It plays the role of completely burning unburned gas contained in the combustion exhaust gas from the catalyst member A3.

Referring again to FIG. 1, the operation of the gas combustion device 24 according to the present invention will be described. Heat is generated in the region of the heat dissipation tube 5 surrounded by reference marks B and C, and it functions as a heating device. First, the solenoid valve 8 is opened to forcefully send combustion air from the blower 7 into the casing 4, and the pilot burner 11 is ignited. Combustion air heated by the pilot burner 11 is supplied under pressure through the heat radiation tube 5, thereby
The catalyst members A1 to A4 in the heat dissipation tube 5 are heated to a temperature at which a catalytic combustion reaction can occur. Catalyst member A1
The temperature rise of ~A4 can be read by the preset heating air supply time or by the temperature detection element 12 disposed on the downstream side of the final stage catalyst member A4.

Next, when the temperature of the catalyst member A1 rises to a temperature that allows a catalytic combustion reaction, for example, 300°C, the pilot burner 11 is extinguished and the control circuit 13 opens the solenoid valve 2 to mix the fuel gas with air. Send it to chamber 6. This combustible gas mixture first flows through the catalyst member A1. Since the catalyst member A1 has the cavity 23 formed in the central part as described above, only the mixed gas that has passed through the peripheral part, that is, the through hole 20 of the base body 21, is catalytically combusted.
The remaining mixed gas flows through the cavity 23 in an unburned state. The ratio of the mixed gas that is catalytically combusted and the mixed gas that is not catalytically combusted and flows through depends on the cross-sectional area ratio of the base body 21 and the cavity 23, and as described above, the D ₁ /D ₂ ratio is approximately By setting it to 1.2, the mixed gas catalytically combusted in the catalyst member A1 can be suppressed to less than about 1/3 of the total flow rate.
The heat generated by the catalytic combustion in the catalyst member A1 not only heats the catalyst member A1 but also raises the temperature of the mixed gas that has passed through the catalyst member A1.
The heat is transmitted to the wall and radiated. Also, catalyst member A1
Since the thickness d is relatively small, this heat dissipation is effective even near the inner peripheral surface where the temperature is most likely to rise, and overheating damage to the catalyst can be prevented. Furthermore, even if the outer circumferential surface 5d of the heat dissipation tube 5 is rapidly cooled, since the base body 21 around the catalyst member A1 has a honeycomb shape, the inner circumference will not cool down.
Therefore, there is no problem in continuing the catalytic combustion reaction.

The combustion gas from the catalyst member A1 is
While dissipating heat from the heat dissipation pipe 5 on the downstream side, the gas mixes with the unburned gas that has passed through the cavity 23, flows through the flow path 10, and flows into the next stage catalyst member A2. In the catalyst member A2, a part of the mixed gas is catalytically combusted in the same manner as in the catalyst member A1, and further flows into the next stage catalyst member A3 in the same manner. The unburned gas contained in the mixed gas from the catalyst member A3 is completely combusted here because the final stage catalyst member A4 does not have a cavity 23, and the combustion exhaust gas is released from the tip 5b of the heat dissipation tube 5. .
The temperature of the combustion exhaust gas is detected by the temperature detection element 12, and the control circuit 13 controls the opening and closing of the electromagnetic valves 2 and 8 so that the temperature remains constant. By controlling the mixing ratio of fuel gas and combustion air in this way, the catalyst members A1 to A4 are kept at a constant temperature suitable for catalytic combustion, and the surface temperature of the entire heat dissipation tube 5 is made uniform. can be achieved.

In addition, when mixing the fuel gas and the combustion air, the flow speeds of the fuel gas and the combustion air are increased in the mixing chamber 6 to maintain a stable flame state and to ensure that no flame exists. The control circuit 13 may set the mixing ratio of the fuel gas and combustion air to be fed to a certain degree. Furthermore, the area of the mixing chamber 6 in the tube axis direction is shortened so that the combustible mixed gas is supplied under pressure to the first catalyst member A1 while the fuel gas and combustion air remain in an incompletely mixed state. In this way, suppressing catalytic combustion in the catalyst member A1 is effective in making the surface temperature distribution of the entire heat dissipation tube 5 uniform.

By forming the relatively large cavity 23 in the center of the previous stage catalyst members A1 to A3 except for the final stage catalyst member A4, the catalyst member A1
~A3 overheating can be avoided, and operation at a low excess air ratio is possible. Moreover, since exhaust loss can be reduced by this, a gas combustion device 24 with high thermal efficiency can be obtained.

FIG. 6 shows a catalyst member A according to another embodiment of the present invention.
5, FIG. 7 is a sectional view taken along the section line - in FIG. 6, and FIG. 8 is an enlarged perspective view of the section in FIG. 6. 6 to 8 are similar to the configurations in FIGS. 3 to 5, and corresponding parts are given the same reference numerals. In this example, the seventh
As shown in the figure, the entire base 25 has a cylindrical honeycomb structure, and the catalyst 22 is supported in the through holes 20 only in the peripheral portion 26 of the base 25 near the wall surface of the heat dissipation tube 5. In this embodiment, the central region 27 along the axial direction of the base body 25 does not support the catalyst 22, so that the heat generated by catalytic combustion is transmitted to the external object to be heated through the heat dissipation tube 5. , will be transmitted to the mixed gas flowing through the central region 27. Therefore, overheating of the region 26 in which the catalyst 22 is supported is more effectively suppressed. Note that this catalyst member A5 is arranged in place of the first-stage catalyst members A1 to A3 in the above-mentioned embodiment, and as in the above-mentioned embodiment, the last-stage catalyst member has through holes throughout the base body 25. A catalyst 22 is supported within the catalyst 20.

FIG. 9 is a sectional view of still another embodiment of the present invention, and FIG. 10 is a diagram for explaining the operation of the bimetal 30. FIG. 9 is similar to the configuration of FIG. 3, and corresponding parts are given the same reference numerals. What should be noted is that there is a bimetal 30 as a heat-sensitive means and a valve 3 that opens and closes the cavity 23 by the bimetal 30 in the middle of the cavity 23 of the base 21 of the catalyst member A1.
1. Inside the cavity 23 of the base body 21 is a cylindrical body 3 that is in close contact with the inner circumferential surface 21b of the base body 21.
2 is installed. The inner wall 32a of the cylindrical body 32 has an L
A letter-shaped bracket 33 is fixed, and an endless annular bimetal 30 is attached to the tip of the bracket 33 via a fixing ring 34. A control valve 31 is integrally attached to the bimetal 30. The valve body 36 of the control valve 31 has a size capable of opening and closing the cavity 23, and automatically opens and closes the cavity 23 by contraction and expansion operations of the bimetal 30.
When the temperature of the catalyst member A1 is low, the bimetal 30 contracts and displaces as shown in FIG. 10. At this time, the valve rod 35 moves in the flow direction C of the mixed gas.
The valve element 36 closes the open end 32b of the cylindrical body 32, thereby blocking the cavity 23. Therefore, at low temperatures, all the mixed gas flows through the base body 21 and is catalytically burned. On the other hand, catalyst member A
When the temperature of 1 is high, the bimetal 30
0 is extended and displaced as shown in Figure 2. At this time, the valve rod 35 is positioned on the downstream side (9th position) in the flow direction C of the mixed gas.
(to the right in the figure), and the valve body 36 separates from the open end 32b of the cylindrical body 32. This makes the cavity 23
is in an open state, and a portion of the mixed gas flows through the cavity 23 without being combusted. In this way, the base 21
By controlling the amount of mixed gas flowing through the base body 21, the flow rate of the mixed gas that performs catalytic combustion within the base body 21 can be controlled, and overheating damage to the catalyst member A1 can be prevented as much as possible. I can do it. Furthermore, the configuration of the catalyst member A1 is the same for the other catalyst members A2 and A3. Therefore, depending on the temperature of the catalyst members A1 to A3, the control valve 3
By automatically performing the opening and closing operations of 1, the temperature of the catalyst members A1 to A3 can be adjusted to
Each can be controlled to automatically maintain a certain level. At the time of ignition of the gas combustion device 24 according to the present invention, the catalyst member A1 heated by the pilot burner can be limited to the catalyst member A1, and the catalyst member A1 can be efficiently heated in the order of A2 → A3. Gas combustion device 24
The responsiveness of the rising edge of is improved.

FIG. 11 is a sectional view of another embodiment of the present invention, and FIG. 12 is a diagram for explaining the operating state of the bimetal 37. FIG. 11 is similar to the configuration of FIG. 9, and corresponding parts are given the same reference numerals.
What should be noted is that a bimetal 37 as a heat-sensitive means and a control valve 38 are provided upstream of the bracket 33 in the mixed gas flow direction C (left side in FIG. 11). The bimetal 37 is integrally fixed to the bracket 33 by a fixing ring 34, and the valve body 39 is integrally attached to a valve stem 41 via a connecting rod 40. Valve body 3
9 has a hole 42 in its center that is approximately the same diameter or smaller than the cavity 23, the outer diameter of which is equal to or slightly smaller than the inner diameter of the discharge pipe 5, and the valve body 39 is It is movable within the heat dissipation tube 5 in the tube axis direction. Moreover, the bimetal 37 is the bimetal 3
It has a configuration that exhibits contraction and expansion modes opposite to zero. When the temperature of the catalyst member A1 is low, the bimetal 37 is expanded and displaced as shown in FIG. 12. This allows the mixed gas to flow through the cavity 23 and the base body 21 from the upstream side of the catalyst member A1 through the through hole 42 of the valve body 39. Further, when the catalyst member A1 is at a high temperature, the bimetal 37 contracts and changes as shown in FIG.
The control valve 38 is in a closed state, and the combustible mixed gas flows only within the cavity 23. Therefore, the ratio between the flow rate of the mixed gas passing through the cavity 23 and the flow rate of the mixed gas passing through the base body 21 is appropriately adjusted depending on the temperature of the catalyst member A1. This prevents the catalyst member A1 from overheating. This also applies to the catalyst members A2 and A3. In this way, the control valve 38 allows automatic combustion control. Further, by providing the control valve 31 shown in FIG. 9 and the control valve 38 shown in FIG. 11 at the same time, the entire heat dissipation pipe 5 can be made more uniform.

In the embodiments shown in FIGS. 9 and 11, bimetals 30 and 37 are used as the heat-sensitive means, but it is also possible to use a material that deforms depending on temperature, such as a shape memory alloy, or use other constructions. It may be.

The gas combustion device according to the present invention is not limited to industrial furnaces, but can be implemented in a wide range of technical fields such as boilers and heating devices.

Effects As described above, according to the present invention, a plurality of catalyst members are arranged in the axial direction of the heat dissipation tube, a combustible mixed gas flows through the heat dissipation tube, and the flammable mixed gas is converted by the catalyst members. By performing catalytic combustion, it is possible to obtain a uniform temperature distribution over the entire heat dissipation tube. Further, by making the catalyst member have a honeycomb structure, the manufacturing process of the heat dissipation tube is also simplified.
In particular, according to the present invention, as clearly shown in FIGS. 3, 4, 6, and 7, the base body 21 is in contact with the inner circumferential surface of the heat dissipation tube 5, and its outer diameter The ratio of D ₁ to the inner diameter D ₂ of the transmission areas 23 and 27 is D ₁ /
D ₂ is selected to be approximately 1.2, and this base 21 has a cordierite honeycomb structure, and the base 2
Activated alumina is coated on the inner peripheral surface of the through hole 20 near the peripheral part 26 near the wall surface of the heat dissipation tube 5 in No. 1, and a catalyst made of platinum or palladium is supported on the activated alumina. By setting the catalyst ratio to about 0.5 to 3%, the mixed gas catalytically combusted in each of the catalyst members A1 to A3 other than the final stage catalyst member A4 can be suppressed to less than about 1/3 of the total inserted flow rate. In this way, the temperature of the heat dissipation tube 5 along the tube axis direction can be made uniform.

Further, according to the present invention, the base end 5a of the heat dissipation tube 5 is connected to the opening 4a in the end wall of the casing 4, and combustion air is supplied to the air chamber of the casing 4 by the blower 7. A fuel supply pipe 3 that passes through the casing 4 supplies fuel gas made of natural gas, and the distal end 3a of the fuel supply pipe 3 enters the base end 5a of the heat dissipation pipe 5. Moreover, since there is a gap 44 between the outer circumferential surface of the distal end 3a and the inner circumferential surface of the proximal end 5a, the pilot Burner 11
The combustion air in the casing 4 can be supplied and heated in advance, and then fuel gas can be supplied to perform catalytic combustion. In this way, catalytic combustion can be performed immediately upon supply of fuel gas, and heating can be performed with uniform temperature distribution over the entire length of the heat radiation tube 5.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a perspective view of an embodiment of the invention, and Fig. 3 is a catalyst member A.
1, FIG. 4 is a sectional view taken along the section line - in FIG. 3, FIG. 5 is an enlarged perspective view of the section in FIG. 3, and FIG. 6 is a catalyst according to another embodiment of the present invention. A sectional view of member A5, FIG. 7 is a sectional view taken along the cutting plane line - in FIG. 6, FIG. 8 is an enlarged perspective view of the section in FIG. 6, and FIG. 9 is a further embodiment of the present invention. 10 is a cross-sectional view of the bimetal 30
FIG. 11 is a sectional view of another embodiment of the present invention, and FIG. 12 is a diagram for explaining the operating state of the bimetal 37. 5... Heat radiation tube, 12... Temperature detection element, 20...
...Through hole, 21, 25...Substrate, 22...Catalyst, 2
3...Cavity, 24...Gas combustion device, 30, 37
...bimetal, 31,38...control valve.

Claims (1)

[Claims for Utility Model Registration] A casing 4 constituting an air chamber and having an opening 4a in an end wall; a blower 7 that supplies combustion air to the air chamber of the casing 4; a pilot burner 11 that heats the combustion air inside; a heat radiation tube 5 having a base end 5a connected to the opening 4a of the casing 4; and a tip end 3a that enters the base end 5a of the heat radiation tube 5. , a fuel supply pipe 3 having a gap 44 between the outer circumferential surface of the distal end portion 3a and the inner circumferential surface of the proximal end portion 5a, passing through the inside of the casing 4, and supplying fuel gas made of natural gas. A plurality of catalyst members A1 to A3 are disposed at intervals in the tube axis direction of the heat dissipation tube 5, and each of the catalyst members A1 to A3 is disposed coaxially within the heat dissipation tube 5 and A large number of through holes 20 are formed in contact with the inner peripheral surface and extend in the tube axis direction at least near the peripheral portion 26 close to the wall surface of the heat dissipation tube 5, and a flow region 2 is formed near the center of the tube axis.
3 and 27 are formed extending in the tube axis direction.
1, and the outer diameter D ₁ of the base body 21 and the flow area 23,
The ratio D ₁ /D ₂ to the inner diameter D ₂ of 27 is selected to be approximately 1.2, and the base 21 has a cordierite honeycomb structure.
Activated alumina coated on the inner peripheral surface of the through hole 20 near the peripheral portion 26 of the base body 21; A catalyst 22 made of platinum or palladium and supported on the activated alumina, the catalyst being a catalyst for activated alumina. Such catalyst members A1 to A3 including a catalyst 22 with a ratio of about 0.5 to 3%, and a catalyst member A provided in the heat dissipation tube 5 as the final stage.
4, this final stage catalyst member A4 is disposed coaxially within the heat dissipation tube 5, is formed with a large number of through holes uniformly distributed in the tube axis direction over the entire cross section, and is made of cordierite. The base body 21 has a high-quality honeycomb structure, activated alumina is coated on the inner peripheral surface of all the through holes in the base body 21, and platinum or palladium is supported on the activated alumina and completely removes unburned gas from the combustion exhaust gas. Such a catalyst member A comprising a catalyst 22 to be combusted.
4. A gas combustion device characterized by comprising: