JP2000297903A - Catalytic combustion heat source equipment - Google Patents

Abstract

(57) [Problem] To provide a catalytic combustion type heat source device in which the preheating time of a catalyst required at the start of catalytic combustion is shortened and stability with respect to temperature controllability is improved. SOLUTION: A mixture inlet 4 provided in a combustion chamber 5 for supplying a mixture comprising fuel and air, and at least one of a platinum group metal and an oxide of Zr or Ce provided in the combustion chamber 5 Coating layer 1 composed of a carrier mainly composed of
1 is a catalyst body 6 formed on a substrate having a large number of communication holes
And a heat transfer portion 8 in contact with the outside of the combustion chamber 5 and an exhaust port 9 provided in the combustion chamber 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion type heat source device for heating, heating or drying by burning a gaseous fuel or a liquid fuel on a catalyst.

[0002]

2. Description of the Related Art Heat source devices utilizing catalytic combustion instead of electric heaters have been developed, and in recent years, some have been put to practical use as cordless devices such as steamers. Catalytic combustion is a combustion method in which fuel is brought into contact with and activated on the catalyst surface by the action of a catalyst, and is burned at a low temperature and without flame. The combustion-type heat source device has a configuration in which a catalyst body is brought into contact with a wall surface of a combustion chamber having a heat transfer section in order to make the combustion chamber compact and efficiently transmit reaction heat to the heat generation section. Further, the temperature control of the equipment is performed by changing the supply amount of the fuel gas. The catalyst used in such a catalytic combustion type heat source generally contains a platinum-group-based metal with high dispersion, mainly on activated alumina or the like, having a large specific surface area of about 100 g / m ² in order to suppress deterioration due to combustion. The support was used by coating and forming on a heat-resistant porous ceramic base material such as cordierite.

[0003]

Problems to be solved by the conventional catalytic combustion type heat source equipment as described above are to shorten the preheating time of the catalyst required to start catalytic combustion and to reduce the preheating temperature, that is, to reduce the preheating temperature. Low temperature activation. In order to start the combustion reaction on the catalyst, the temperature must be raised to the activation temperature or higher.However, a catalyst support having a high specific surface area such as activated alumina generally used as a support or a base material such as cordierite is used. When used, it took time to preheat the catalyst. This is because the conventional carrier / substrate adsorbs components in the environmental atmosphere such as moisture when not used, that is, when kept at room temperature, and it takes time to desorb the adsorbed components. In order to reduce the water absorption of the catalyst, it is necessary to reduce the specific surface area of the carrier or to form a layer of only platinum group metal to reduce the amount of water absorbed, etc., but sufficient activity and durability can be obtained. Did not. In addition, in order to maintain combustion without causing misfiring, etc. in controlling the temperature of the equipment, it is preferable that the temperature at which combustion is started on the catalyst be lowered, and improvement of the catalyst activity becomes an issue. I was

[0004]

In order to solve the above-mentioned problems, a catalytic combustion type heat source device according to the present invention comprises: a mixture inlet provided in a combustion chamber for supplying a mixture comprising fuel and air;
A catalyst body in which a catalyst coating layer composed of a carrier mainly composed of at least one of a platinum group metal and an oxide of Zr or Ce provided in a combustion chamber is formed on a substrate having a large number of communication holes; And a heat transfer portion contacting the outside of the combustion chamber, and an exhaust port provided in the combustion chamber. At this time, the base material is preferably an Al-containing ferrite-based metal, and the catalyst coating layer preferably contains 1 to 10% by weight of Al or Si oxide fine particles.

Further, the catalytic combustion type heat source equipment of the present invention comprises a mixture inlet provided in the combustion chamber for supplying a mixture comprising fuel and air, a platinum group metal provided in the combustion chamber,
a catalyst body in which a catalyst coating layer composed of a carrier mainly composed of at least one of r and Ce oxides is formed on a substrate having a large number of communication holes, and heat transfer in contact with the outside of a combustion chamber And an exhaust port provided in the combustion chamber, and at least one of V, Mo, W, a platinum group metal, and Zr, Ce, on the downstream side in the fuel supply direction of the catalyst coating layer.
A catalyst layer comprising at least one of Ti oxides is provided. At this time, it is preferable that the catalyst coating layer and the catalyst layer are provided so as to be laminated on the same base material.

[0006]

FIG. 1 is a sectional view of a main part of a first embodiment of the present invention. The fuel gas supplied from the fuel supply valve 1 is mixed with the air supplied from the air supply valve 2 in the mixing chamber 3, and supplied from the mixture inlet 4 to the catalyst 6 located in the combustion chamber 5. The air-fuel mixture is ignited by the ignition device 7 and forms a flame downstream of the catalyst body 6. When the temperature of the downstream side of the catalyst body 6 is raised to the activation temperature for fuel or higher by the flame, catalytic combustion starts from the downstream side of the catalyst body 6,
Next, the heat of combustion on the downstream side is transferred to the upstream side of the catalyst body 6, where catalytic combustion is started. The heat generated by the catalytic combustion is used as a heat source via a heat transfer section 8 in contact with the combustion chamber, and the exhaust gas is discharged to the outside via an exhaust port 9. In addition, temperature control of heat source equipment
This is performed by stopping the supply of fuel when the temperature exceeds a predetermined temperature by a temperature sensor 10 provided on the outer wall surface of the combustion chamber. Therefore, the supply stop is repeated by opening and closing the fuel supply valve 1.

In the present invention, a catalyst coating layer 11 composed mainly of a Zr or Ce oxide carrying a platinum group metal is formed on a heat-resistant metal substrate 12 on a catalyst body 6 functioning as a combustion catalyst. It is characterized by using. Zr of catalyst coating layer
A platinum group metal such as Pt is dispersed and supported on O ₂ , and functions as an active point of catalytic combustion. By using ZrO ₂ as a carrier of the platinum group metal, the platinum group metal is appropriately dispersed, the activity is increased, and at the same time, the aggregation is suppressed to promote a longer life. Further, the same effect can be obtained by using CeO
₂ and also when a composite oxide of Ce and Zr is used. In addition, since the specific surface area is smaller than that of activated alumina or the like, the amount of water adsorbed when not used is reduced, and the amount of heat required for evaporating water during preheating of the catalyst can be reduced. Therefore, the preheating time of the catalyst can be reduced, and the steady state catalytic combustion can be started more quickly.

Further, since the base material is made of a Fe ₂₀ Cr ₅ Al ferrite-based metal, the amount of water absorbed by the base material is almost ignored, and the combustion heat is transferred to the upstream side. Preheating time can be suppressed. At the same time, the effect of improving the carrier is more clearly exhibited. In reviewing the several stainless steel, Fe ₂₀ C
The r ₅ Al ferrite-based metal is excellent in heat resistance and oxidation resistance because an aluminum oxide film is formed on the surface by heating, and has relatively good adhesion to a catalyst, and is most preferable as a catalyst base material.

Further, in the present invention, the film strength of the catalyst coating layer containing Zr or Ce oxide as a main component containing a minimum amount of Al or Si oxide fine particles selected from the range of 1 to 10% by weight. This prevents the catalyst coating layer from peeling off due to long-term use.

Further, in the present invention, at least one of V, Mo, and W is used as in the laminated catalyst coating layer shown in FIG.
A catalyst layer composed of a platinum group metal and at least one of Zr, Ce and Ti oxides is a catalyst coating layer composed of at least one of a Zr or Ce oxide carrying a platinum group metal. Are provided on the downstream side with respect to the fuel supply direction. Zr, C with V, Mo, W added
The e and Ti oxide carriers, or their composite oxides, have the effect of improving the low-temperature activity for the oxidation of fuels having a carbon-carbon bond, such as butane, of a platinum group metal catalyst. Such an effect is particularly high among Pt metals.
Significant in the case of t. When V, Mo, and W are added, decomposition and sublimation occur with an increase in the use temperature, and deterioration is likely to occur. Therefore, in the present invention, the catalyst is provided downstream of the catalyst body that starts catalytic combustion, acts only at the start of combustion, and does not always come to the main combustion position (the position that indicates the highest temperature due to combustion) to reduce catalyst deterioration. ing. Although the portion to be laminated differs depending on the use conditions, in the present embodiment, the downstream side is 3 mm.
It was sufficient to stack to the extent.

[0011]

(Example 1) Metal honeycomb (material Fe ₂₀ C)
r ₅ Al steel, 400 cells / inch ² equivalent, wall thickness 0.0
90 g of ZrO ₂ powder, 40 g of water, 4 g of Pt dinitrodiammine salt aqueous solution, 4 g of Pt conversion, 20 wt% Al ₂
The impregnated washcoat slurry A obtained by adding 5 g of O ₃ sol as a solid content is dried, baked at 500 ° C.
A catalyst coating layer is formed by carrying 3 g / L equivalent,
Catalyst body 6 was obtained. Next, the catalyst body 6 obtained above was mounted on the catalytic combustion apparatus shown in FIG. In the combustion test, isobutane gas was used as the fuel, and the premixed gas supplied to the combustion chamber was an excess air ratio λ (the ratio of the actual supply air amount to the theoretical air amount) = 1.1 and the combustion amount was 60 kcal / h. In order to check the time to start catalytic combustion, a flame is formed at the downstream end of the catalyst body and preheated, the time from the start of catalytic combustion to the extinguishing of the flame `` flame extinguishing time '', and the entire surface glows red The time until the "burning start time" was examined. Further, after the fuel is stably burned for about 15 minutes, the fuel supply valve 1 is forcibly closed, and when the catalyst downstream temperature reaches a predetermined temperature, the fuel supply valve 1 is reopened. A certain "reburning start temperature" was examined. Further, as a combustion life test, a combustion amount of 80 kcal / h, an excess air ratio λ = 1.1
The catalytic combustion was performed under the conditions for 1000 hours.

(Example 2) Metal honeycomb (material Fe ₂₀
Cr ₅ Al steel, 400 cells / inch ² equivalent, wall thickness 0.0
90 g of CeO ₂ powder, 40 g of water, 4 g of Pt-dinitrodiammine salt aqueous solution, 4 g of Pt-equivalent, 20 wt% Al ₂
The impregnated washcoat slurry A ′ containing 5 g of O ₃ sol in solid content is dried, baked at 500 ° C.
A catalyst coating layer was formed by carrying t3 g / L equivalent, and catalyst body 6 was obtained. The same test as in Example 1 was performed by mounting the catalyst body 6 obtained above in the catalytic combustion apparatus shown in FIG.

(Embodiment 3) Metal honeycomb (material Fe ₂₀
Cr ₅ Al steel, 400 cells / inch ² equivalent, wall thickness 0.0
90 g of ZrO ₂ powder, 40 g of water, 4 g of an aqueous solution of Pt dinitrodiammine salt in terms of Pt, 4 g of 20 wt% Al 2
Wash coat slurry A containing 5 g of O3 sol in solid content is impregnated, dried and calcined at 500 ° C. to form Pt.
A catalyst coating layer was formed by carrying 3 g / L equivalent. Next, ZrO containing 5 wt% W fired at 500 ° C.
₂ powder 90 g, water 40 g, 4g of Pt dinitrodiammine salt solution in terms of Pt, the 20 wt% Al ₂ O ₃ sol made by adding 5g of solid content washcoat slurry B was impregnated with one end of the catalyst, the Pt The catalyst body 6 was obtained by carrying 0.5 g / L equivalent. The same test as in Example 1 was performed by mounting the catalyst body 6 obtained above on the catalytic combustion apparatus shown in FIG. 1 with the surface to which the washcoat slurry B was attached facing downstream.

(Comparative Example 1) Metal honeycomb (material Fe ₂₀
Cr ₅ Al steel, 400 cells / inch ² equivalent, wall thickness 0.0
5, 20φ, length 10) were prefired at 1000 ° C. for 1 hour, 90 g of γ-Al ₂ O ₃ powder, 100 g of water, 4 g of a Pt dinitrodiammine salt aqueous solution in terms of Pt, 20 wt%
The impregnated washcoat slurry C obtained by adding 5 g of Al ₂ O ₃ sol as a solid content is dried, baked at 500 ° C.,
A catalyst coating layer was formed by carrying Pt equivalent to 3 g / L, and a catalyst body 6 was obtained. The same test as in Example 1 was performed by mounting the catalyst body 6 obtained above in the catalytic combustion apparatus shown in FIG.

Comparative Example 2 Ceramic Honeycomb (Material)
Quality cordierite, 400 cells / inch^TwoEquivalent, wall thickness
0.15, 20φ, length 10) at 1000 ° C for 1 hour
Pre-fired ZrO _Two90g powder, 40g water, Pt gini
4 g of Pt equivalent, 20 wt%
Al_TwoO_ThreeWash co with 5 g of sol added as solid
Impregnated in the slurry A, dried and calcined at 500 ° C.
A catalyst coating layer is formed by supporting Pt equivalent to 3 g / L
Thus, a catalyst body 6 was obtained. The catalytic combustion device shown in FIG.
The same test as in Example 1 was performed with the obtained catalyst body 6 attached.
Was.

Comparative Example 3 Metal Honeycomb (Material Fe ₂₀
Cr ₅ Al steel, 400 cells / inch ² equivalent, wall thickness 0.0
90 g of ZrO ₂ powder, 40 g of water, 4 g of Pt dinitrodiammine salt aqueous solution, 4 g of Pt conversion, 20 wt% Al ₂
The impregnated washcoat slurry A obtained by adding 5 g of O ₃ sol as a solid content is dried, baked at 500 ° C.
A catalyst coating layer is formed by carrying 3 g / L equivalent,
A catalyst body was obtained. Further, one end of the catalyst body was impregnated with the washcoat slurry A, and Pt was supported at a rate of 0.5 g / L to obtain a catalyst body 6. The same test as in Example 1 was performed by mounting the catalyst body 6 obtained above in the catalytic combustion apparatus shown in FIG.

In Examples 1 to 3 and Comparative Examples 1 to 3, the flame formed at the downstream end of the catalyst body 6 activates the downstream portion of the catalyst, and the downstream side partially starts catalytic combustion to extinguish the flame. Table 1 shows the results obtained by examining the time “flame extinguishing time” and the time “combustion start time” until the combustion position is performed on the entire upstream surface of the catalyst.

[0018]

[Table 1]

In Example 1, the flame quenching time was shorter than in Comparative Example 1. This is because, as shown in FIG. 3, the use of the ZrO ₂ carrier slightly improves the low-temperature combustion activity of butane. Similar effects were observed with the CeO ₂ carrier of Example 2 and with the use of a composite of ZrO ₂ and CeO ₂ . Further, with respect to the combustion start time, in Example 1,
In the case of No. 2, it was significantly shortened as compared with the comparative example 1. As can be seen from the thermal desorption profile shown in FIG. 4, in the case of the ZrO ₂ carrier, the amount of desorbed water at the time of temperature elevation is extremely smaller than that of γ-Al ₂ O ₃ used in Comparative Example 2. Since the combustion start time includes the amount of heat for evaporating the adsorbed water, the high surface area Al
It is considered that ₂ O ₃ requires much time.

As is clear from the comparison between Example 1 and Comparative Example 2, the use of metal as the base material can further shorten the combustion start time. This is because the ceramic substrate itself also absorbs water, and the effect of the ZrO ₂ carrier was more clearly exhibited. Further, by using a metal base material, heat can be easily made uniform, so that a local increase in catalyst temperature due to combustion can be suppressed, so that a preheating operation can be performed with a higher combustion amount. Note that ZrO ₂ and CeO ₂
The amount of fine particles of Al ₂ O _3, which is a film forming aid, is 10 wt.
% Did not significantly affect the performance. Similar effects were obtained by using SiO ₂ fine particles.

Further, as can be seen from the comparison between Example 3 and Comparative Example 3, in Example 3, W / Zr
By providing the Pt supported on O ₂ in a stacked manner, the combustion start time was shortened as compared with a simple stack of Pt supported on ZrO 2. Further, the flame extinction time is also particularly shortened, and the effect of suppressing the generation of NOx due to the flame preheating is also exhibited. This is because, as shown in FIG. 5, the addition of W to ZrO ₂ significantly improves the isobutane oxidation activity of Pt. The same effect was considered to be related to the solid acidity of the carrier, and was also exhibited when Mo or V was added or when the same treatment was performed on CeO ₂ or TiO ₂ .

Next, Table 2 shows the results of examining the temperature at which combustion can be performed when fuel supply is stopped and re-supplied, ie, "reburning start temperature".

[0023]

[Table 2]

As is clear from Table 2, by adopting the catalyst configuration of the third embodiment, the recombustion start temperature is also greatly reduced, and the temperature control of the equipment can be performed with more margin. Can be.

In this example and the comparative example, the temperature change of the main combustion surface (upstream of the catalyst) during the combustion life test shows the same tendency.
It has been clarified that even when ZrO ₂ or CeO ₂ is used as a carrier, or when a stacked catalyst is used, the change in performance during steady combustion is not affected. FIG. 6A shows the change over time of the flame extinction time, and FIG. 6B shows the change over time of the combustion start time in Examples 1 and 3 and Comparative Example 1. Although the ZrO ₂ support had a smaller specific surface area than γ-Al ₂ O ₃ , it was possible to maintain a short preheating time. On the other hand, in Example 3, although a performance decrease was recognized from the beginning, it was possible to maintain a short flame quenching time even in comparison with Examples 1 and 2 and Comparative Examples 1 to 3. In the third embodiment, a catalyst layer composed of at least one of V, Mo, and W, a platinum group metal, and at least one of Zr, Ce, and Ti oxide is formed of a catalyst such as Pt / ZrO _2. Although the catalyst body 6 is provided by being laminated on the downstream side of the medium, the catalyst body 6 may be supported on a similar metal honeycomb or a heat-resistant fiber separately in the vicinity of the downstream side of the catalyst body 6 and used as the catalyst body.

[0026]

As is clear from the above description of the embodiment,
ADVANTAGE OF THE INVENTION According to this invention, the preheating time required for the start of catalytic combustion can be shortened greatly, and the stability with respect to temperature controllability can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a catalytic combustion device of the present invention.

FIG. 2 is a view showing a cross section of a laminated catalyst of the present invention.

FIG. 3 is a diagram showing the oxidation activity of the catalyst used in Example 1 and Comparative Example 1 of the present invention.

FIG. 4 is a graph showing a temperature-removed desorption profile of a catalyst used in one embodiment of the present invention after being left in air.

FIG. 5 is a diagram showing the oxidation activity of a catalyst used in Example 3 of the present invention.

FIG. 6 (a) is a diagram showing a change over time of a main combustion surface temperature with a combustion life time in Examples and Comparative Examples of the present invention. (B) A diagram showing a change over time in the combustion start time.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fuel supply valve 2 Air supply valve 3 Mixing chamber 4 Mixture inlet 7 Combustion chamber 6 Catalyst 7 Ignition device 8 Heat transfer part 9 Exhaust port 10 Temperature sensor 11 Catalyst coating layer 12 Heat resistant metal base material 13 V, Mo, W , A platinum group metal, and at least one of Zr, Ce, and Ti oxides

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshitaka Kawasaki 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. F term (reference) 3K065 TA13 TB09 TC05 TD04 TD05 TK02 TK04 TK06

Claims (5)

[Claims] 1. A mixture inlet provided in a combustion chamber for supplying a mixture comprising fuel and air, and at least one of a platinum group metal and an oxide of Zr or Ce provided in the combustion chamber. A catalyst body formed on a base material having a large number of communication holes formed by a catalyst coating layer composed of a carrier, a heat transfer unit brought into contact with the outside of the combustion chamber, and exhaust gas provided in the combustion chamber A catalytic combustion type heat source device comprising a mouth. 2. The catalytic combustion heat source device according to claim 1, wherein the base material is an Al-containing ferritic metal. 3. The catalytic combustion heat source device according to claim 1, wherein the catalyst coating layer contains 1 to 10% by weight of Al or Si oxide fine particles. 4. A mixture inlet provided in the combustion chamber for supplying a mixture comprising fuel and air, and at least one of a platinum group metal and an oxide of Zr or Ce provided in the combustion chamber. A catalyst body formed on a base material having a large number of communication holes formed by a catalyst coating layer composed of a carrier, a heat transfer unit brought into contact with the outside of the combustion chamber, and exhaust gas provided in the combustion chamber And at least one of V, Mo, and W, a platinum group metal, and at least one of Zr, Ce, and Ti oxide on the downstream side in the fuel supply direction of the catalyst coating layer. A catalytic combustion type heat source device comprising a catalyst layer to be provided. 5. The catalytic combustion type heat source device according to claim 4, wherein the catalyst coating layer and the catalyst layer are provided on the same base material.