Catalytic reaction heater

Abstract

A catalytic reaction heater includes a plurality of catalytic reacting sections for generating a high-temperature gas based on a catalytic reaction of fuel and oxygen, and a plurality of heat exchanging sections for increasing the temperature of a circulating heating medium based on heat exchange between the heating medium and the gas. The catalytic reacting sections and the heat exchanging sections are alternately and serially disposed along a flowing direction of the gas. A supply amount of the fuel and oxygen supplied into an upstream end catalytic reacting section is set to a value exceeding a maximum consumable level in this upstream end catalytic reacting section.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a catalytic reaction heater that utilizes a catalytic reaction to obtain heat energy for increasing the temperature of a heating medium.

The catalytic reaction heater includes a catalytic reacting section whose reaction temperature must be controlled so as not to exceed a predetermined temperature level (for example, a heat resisting temperature of the catalyst). The reaction temperature of the catalytic reacting section becomes higher when an excess air ratio (i.e. a ratio of an actually supplied air amount to a theoretically required air amount for complete combustion) approaches to 1. Accordingly, controlling the reaction temperature of the catalytic reacting section is feasible by adjusting the excess air ratio.

Furthermore, to control the temperature of a reacting system, there is a conventional arrangement consisting of a plurality of separated catalytic reacting sections assembled with a plurality of heat exchangers interposed between these separated catalytic reacting sections (for example, refer to Japanese Patent Application Laid-open No. 3-181338).

However, according to the above-described excess air ratio control method, the excess air ratio must be maintained at a higher value exceeding 1 to suppress the reaction temperature to a low level. A large-scale air supplying section will be required.

On the other hand, according to the latter catalytic reaction heater, it is impossible to control the temperature at a catalytic reacting section disposed at the upstream end (hereinafter, referred to as “upstream end catalytic reacting section”) and accordingly there is the possibility that the upstream end catalytic reacting section may cause an excessive amount of catalytic reaction which possibly induces thermal runaway and as a result may damage the catalyst.

SUMMARY OF THE INVENTION

In view of the above-described problems, the present invention has an object to provide a catalytic reaction heater capable of downsizing an air supplying section as well as suppressing the thermal runaway and eliminating damage of the catalyst.

In order to accomplish the above and other related objects, the present invention provides a first catalytic reaction heater including a plurality of catalytic reacting sections for generating a high-temperature gas based on a catalytic reaction of fuel and oxygen, and a plurality of heat exchanging sections for increasing the temperature of a circulating heating medium based on heat exchange between the heating medium and the gas, wherein the catalytic reacting sections and the heat exchanging sections are alternately and serially disposed along a flowing direction of the gas, and a supply amount of the fuel and oxygen supplied into an upstream end catalytic reacting section is set to a value exceeding a maximum consumable level in the upstream end catalytic reacting section.

According to the first catalytic reaction heater of the present invention, the upstream end catalytic reacting section receives an excessive amount of fuel and oxygen. Only a part of the supplied fuel reacts with the oxygen in the upstream end catalytic reacting section. The residual fuel and oxygen, as a non-reacted gas, pass through the upstream end catalytic reacting section. The reaction heat generated in the upstream end catalytic reacting section is consumed as temperature increasing energy used for increasing the temperature of the non-reacted gas. Therefore, the reaction temperature at the upstream end catalytic reacting section is lower than a theoretical combustion temperature attainable when all of the supplied fuel is completely consumed through the catalytic reaction in the upstream end catalytic reacting section.

Furthermore, all of the gas having passed through the upstream end catalytic reacting section is cooled by a succeeding heat exchanging section and is introduced into a next downstream catalytic reacting section. Then, the reaction heat generated in the next downstream catalytic reacting section is consumed as temperature increasing energy used for increasing the temperature of a cooled gas. Thus, the next downstream catalytic reacting section causes a catalytic reaction at a low temperature.

Accordingly, even if the oxygen amount supplied to the upstream end catalytic reacting section is set to be closer to the theoretical air-fuel ratio, the reaction temperature rise at each catalytic reacting section is small. In other words, there is no necessity of increasing the excess air ratio to a higher value exceeding 1 to suppress the reaction temperature to a low temperature. The air supplying section can be downsized. Furthermore, each catalytic reacting section can suppress its reaction temperature to a predetermined lower temperature. Therefore, the first catalytic reaction heater suppresses the thermal runaway and accordingly prevents the catalyst from being damaged.

Furthermore, to accomplish the above and other related objects, the present invention provides a second catalytic reaction heater including a plurality of catalytic reacting section for generating a high-temperature gas based on a catalytic reaction of fuel and oxygen, and a plurality of heat exchanging sections for increasing the temperature of a circulating heating medium based on heat exchange between the heating medium and the gas, wherein the catalytic reacting sections and the heat exchanging sections are alternately and serially disposed along a flowing direction of the gas, the fuel is supplied separately to each of the plurality of catalytic reacting sections, and all of the supplied oxygen is introduced into an upstream end catalytic reacting section.

According to the second catalytic reaction heater of the present invention, the fuel is separately supplied to each catalytic reacting section. Therefore, even if the oxygen amount supplied to the upstream end catalytic reacting section set to be closer to the theoretical air-fuel ratio, the excess air ratio of each catalytic reacting section can be set to a higher value exceeding 1. Each catalytic reacting section can suppress its reaction temperature to a predetermined lower temperature. Therefore, the second catalytic reaction heater realizes a downsizing of the air supplying section. Furthermore, the second catalytic reaction heater suppresses thermal runaway and accordingly prevents the catalyst from being damaged.

Furthermore, to accomplish the above and other related objects, the present invention provides a third catalytic reaction heater including a plurality of catalytic reacting section for generating a high-temperature gas based on a catalytic reaction of fuel and oxygen, and a plurality of heat exchanging sections for increasing the temperature of a circulating heating medium based on heat exchange between the heating medium and the gas, wherein the catalytic reacting sections and the heat exchanging sections are alternately and serially disposed along a flowing direction of the gas, the oxygen is supplied separately to each of the plurality of catalytic reacting sections, and all of the supplied fuel is introduced into an upstream end catalytic reacting section.

According to the third catalytic reaction heater of the present invention, the oxygen is separately supplied to each catalytic reacting section. Therefore, the third catalytic reaction heater can reduce the excess air ratio to a lower value smaller than 1 so as to suppress the reaction amount in each catalytic reacting section. Furthermore, the third catalytic reaction heater can release the reaction heat to the non-reacted fuel. Each catalytic reacting section can suppress its reaction temperature to a predetermined lower temperature. Therefore, the third catalytic reaction heater realizes downsizing of the air supplying section. Furthermore, the third catalytic reaction heater suppresses thermal runaway and accordingly prevents the catalyst from being damaged.

Furthermore, in any one of the above-described first to third catalytic reaction heaters of the present invention, it is preferable that one of the catalytic reacting sections and one of the heat exchanging sections are serially disposed in one casing so as to constitute each one of a plurality of units connected to each other. According to this arrangement, assembling the manufactured components is easy. Changing the reaction amount is easily feasible by changing the total number of units to be combined.

Furthermore, in any one of the above-described first to third catalytic reaction heaters of the present invention, it is preferable that a temperature sensor detecting the temperature of the gas is disposed at a downstream side of the heat exchanging section, and at least one of a supply amount of the oxygen and a circulation amount of the heating medium is adjusted based on a signal of the temperature sensor so that the temperature of the gas becomes equal to or lower than a pre-designated temperature. According to this arrangement, the reaction temperature of each catalytic reacting section can be surely suppressed to a predetermined lower temperature by adjusting the gas temperature.

Furthermore, in any one of the above-described first to third catalytic reaction heaters of the present invention, the supply amount of the fuel and oxygen supplied into the catalytic reacting sections is set in such a manner that the supplied fuel is completely consumed upon accomplishment of the catalytic reaction in a downstream end catalytic reacting section. According to this arrangement, all of the non-reacted fuel is completely consumed when the downstream end catalytic reacting section has accomplished the catalytic reaction. Therefore, the catalytic reaction heater does not discharge the non-reacted fuel to the outside.

Furthermore, in any one of the above-described first to third catalytic reaction heaters of the present invention, the fuel is hydrogen. According to this arrangement, higher reactivity of the hydrogen is usable. The catalytic reaction heater can perform a warm-up operation based on a self-sustaining reaction at a low temperature. Furthermore, the catalytic reaction heater is preferably applicable, for example, to a warm-up heating source for a fuel battery system using hydrogen fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description which is to be read in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with a first embodiment of the present invention;

FIG. 2 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with a second embodiment of the present invention;

FIG. 3 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with a third embodiment of the present invention;

FIG. 4 is a schematic view showing one of units shown in FIG. 3;

FIG. 5 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with a fourth embodiment of the present invention; and

FIG. 6 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with a fifth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be explained hereinafter with reference to attached drawings.

First Embodiment

Hereinafter, a first embodiment of the present invention will be explained with reference to FIG. 1. FIG. 1 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with the first embodiment of the present invention.

In FIG. 1, a casing 10 has a gas passage in which a gas flows. An upstream end portion of this gas passage is a gas mixing portion 11 for mixing fuel and air. A fuel supplying section 20 supplies fuel into the gas mixing portion 11. An air supplying section 30 supplies air into the gas mixing portion 11. The fuel used in this embodiment is hydrogen that possesses excellent reactivity.

Two catalytic reacting sections 41 and 42, provided in the gas passage, respectively causes a catalytic reaction of a mixed gas consisting the supplied fuel and the supplied air (i.e. oxygen) to generate a high-temperature gas. Two heat exchanging sections 51 and 52, provided in the gas passage, respectively cause heat exchange between a heating medium and the high-temperature gas generated in respective catalytic reacting sections 41 and 42. Two catalytic reacting sections 41 and 42 and two heat exchanging sections 51 and 52 are alternately and serially disposed along a flowing direction of the mixed gas. More specifically, a first catalytic reacting section 41 is disposed at a downstream side of the gas mixing portion 11. A first heat exchanging section 51 is disposed at a downstream side of the first catalytic reacting section 41. A second catalytic reacting section 42 is disposed at a downstream side of the first heat exchanging section 51. And, a second heat exchanging section 52 is disposed at a downstream side of the second catalytic reacting section 42. In this manner, the first catalytic reacting section 41, the first heat exchanging section 51, the second catalytic reacting section 42, and the second heat exchanging section 52 are sequentially disposed in this order from the upstream to the downstream along the flowing direction of the mixed gas.

Each of the first catalytic reacting section 41 and the second catalytic reacting section 42 has numerous holes for allowing the mixed gas to pass through an oxide catalyst containing Pt (i.e. platinum), Pd (i.e. palladium), or other noble metals or metallic oxides having excellent reaction activity at low temperatures which are carried by a ceramic monolith.

Each of the first heat exchanging section 51 and the second heat exchanging section 52 is a fin tube type heat exchanger that includes numerous multilayered tubes and interposing fins. The mixed gas flows outside respective tubes, while a heating medium, such as cooling water, flows inside the tubes.

A cooling water path 60, connected to the first heat exchanging section 51 and the second heat exchanging section 52, is provided with a circulating pump 61 and a fuel battery 62 which are serially arranged. The circulating pump 61 has a function of circulating the cooling water. The fuel battery 62 is disposed at a downstream side of the circulating pump 61 to receive the heated cooling water. In other words, the thermal energy conveyed by the heated cooling water is used to warm up the fuel battery 62. The fuel battery 62 generates electric energy based on a chemical reaction between hydrogen and oxygen.

The catalytic reaction heater includes a control section 70 for various controls. The control section 70 generates control signals which are fed to the fuel supplying section 20, the air supplying section 30, and the circulating pump 61, respectively.

The catalytic reaction heater, having the above-described arrangement, operates in the following manner.

First, in response to a startup operation of the catalytic reaction heater, the control section 70 sends control signals to the fuel supplying section 20, the air supplying section 30, and the circulating pump 61 to start their operations.

The fuel supplying section 20 supplies fuel to the gas mixing portion 11, while the air supplying section 30 supplies air to the gas mixing portion 11. The supplied hydrogen and the supplied air are mixed in the gas mixing portion 11. The mixed gas is supplied from the gas mixing portion 11 into the first catalytic reacting section 41. The first catalytic reacting section 41 causes a catalytic reaction to heat the mixed gas. The first catalytic reacting section 41 thus outputs a high-temperature gas.

In this case, a total amount of the fuel and air supplied to the gas mixing portion 11 is set to a level exceeding a maximum amount to be consumed through the catalytic reaction in the first catalytic reacting section 41. In other words, a spatial velocity (hereinafter, referred to as ‘SV’) is set to such a higher value that the combustion reaction of the mixed gas cannot be fully accomplished in the first catalytic reacting section 41.

In the case that such a higher SV value is set, only a part of the supplied fuel reacts with the oxygen in the first catalytic reacting section 41. The residual fuel and oxygen, as a non-reacted gas, pass through the first catalytic reacting section 41. The reaction heat generated in the first catalytic reacting section 41 is consumed as temperature increasing energy used for increasing the temperature of the non-reacted gas. The reaction temperature in the first catalytic reacting section 41 is lower than a theoretical combustion temperature attainable when all of the supplied fuel is consumed through the catalytic reaction in the first catalytic reacting section 41. Accordingly, the reaction temperature in the first catalytic reacting section 41 can be suppressed within a predetermined upper limit temperature (for example, a heat resisting temperature of the catalyst accommodated in the first catalytic reacting section 41) by adequately setting the SV value.

All of the gas having passed through the first catalytic reacting section 41 (i.e. both the non-reacted gas and the reacted gas) is then introduced into the first heat exchanging section 51 and is cooled by the cooling water through heat exchange between the heated gas and the cooling water. Then, the gas flows into the second catalytic reacting section 42.

In the second catalytic reacting section 42, the non-reacted gas causes a catalytic reaction to produce a high-temperature gas. Then, the reaction heat generated in the second catalytic reacting section 42 is consumed as temperature increasing energy used for increasing the temperature of the reacted gas having been cooled in the first heat exchanging section 51. Therefore, the reaction temperature in the second catalytic reacting section 42 can be suppressed to a lower level. Accordingly, the reaction temperature in the second catalytic reacting section 42 can be suppressed within a predetermined upper limit temperature (for example, a heat resisting temperature of the catalyst accommodated in the second catalytic reacting section 42) by adequately setting the SV value. In this case, the total amount of the fuel and air supplied to the gas mixing portion 11 is set to a level where all of the supplied fuel is completely consumed upon accomplishment of the catalytic reaction in the second catalytic reacting section 42.

All of the gas (i.e. reacted gas) having passed through the second catalytic reacting section 42 is then introduced into the second heat exchanging section 52 and is cooled by the cooling water through heat exchange between the heated gas and the cooling water. Then, the gas is discharged out of the casing 10. On the other hand, the cooling water has a higher temperature as a result of heat exchange with the heated gas. The circulating pump 61 forcibly circulates the cooling water in the cooling water path 60. Thus, the fuel battery 70 is heated (i.e. warmed up) by the circulating high-temperature cooling water.

According to the above-described first embodiment, even if the air amount supplied to the first catalytic reacting section 41 is set to a value closer to a theoretical air-fuel ratio, it is possible to suppress the reaction temperature rise in respective catalytic reacting sections 41 and 42. Namely, there is no necessity of increasing the excess air ratio to a higher value exceeding 1. Accordingly, the first embodiment can realize a downsizing of the air supplying section 30. Furthermore, each of the catalytic reacting sections 41 and 42 can suppress its reaction temperature to a predetermined lower temperature. Therefore, the first embodiment suppresses thermal runaway and accordingly prevents the catalyst from being damaged.

Furthermore, the first embodiment sets the total amount of the fuel and air supplied to the gas mixing portion 11 to a level where all of the supplied fuel is consumed thoroughly upon completion of the catalytic reaction in the second catalytic reacting section 42. Thus, the first embodiment can prevent the non-reacted fuel from being discharged out of the heater.

Second Embodiment

Next, a second embodiment of the present invention will be explained with reference to FIG. 2. This embodiment is different from the first embodiment in that a temperature sensor 71 is provided. FIG. 2 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with the second embodiment of the present invention. The components identical or equivalent to those disclosed in the first embodiment are denoted by the same reference numerals and will not be explained hereinafter.

In FIG. 2, the temperature sensor 71 is disposed at a downstream side of the first heat exchanging section 51 and at an upstream side of the second catalytic reacting section 42. The temperature sensor 71 is connected to the control section 70. Furthermore, the temperature sensor 71 outputs an electric signal representing the temperature of the gas having passed through the first heat exchanging section 51. The electric signal generated from the temperature sensor 71 is sent to the control section 70.

According to the above-described arrangement of the second embodiment, the control section 70 makes a judgment based on the signal obtained from the temperature sensor 71 as to whether or not the temperature of the gas having passed through the first heat exchanging section 51 is equal to or higher than a pre-designated temperature. Then, based on the judgment result, the control section 70 controls the operation of the circulating pump 61 so as to adjust the cooling water amount flowing in the cooling water path 60 in such a manner that the temperature of the gas having passed through the first heat exchanging section 51 is equalized with the pre-designated temperature or less. Alternatively, it is possible for the control section 70 to control the supply amount of the oxygen based on the judgment result in such a manner that the temperature of the gas having passed through the first heat exchanging section 51 is equalized with the pre-designated temperature or less.

Accordingly, the second embodiment can stabilize the temperature of the gas flowing into the second catalytic reacting section 42. Thus, the second embodiment can surely suppress the reaction temperature in the second catalytic reacting section 42 to a predetermined lower temperature.

The reaction heat generated in the first catalytic reacting section 41 is consumed as temperature increasing energy used for increasing the temperature of the non-reacted gas. Therefore, the consumed amount of the temperature increasing energy for the non-reacted gas will change in accordance with increase or decrease of the air amount supplied into the first catalytic reacting section 41. This will result in a temperature change of the gas passing through the first catalytic reacting section 41 and also a temperature change of the gas passing through the first heat exchanging section 51. Accordingly, controlling the air amount supplied into the first catalytic reacting section 41 based on the temperature of the gas having passed through the first heat exchanging section 51 can bring the same effects as those of the above-described embodiment. Furthermore, controlling the cooling water amount flowing in the cooling water path 60 in addition to the air amount supplied into the first catalytic reacting section 41 based on the temperature of the gas having passed through the first heat exchanging section 51 can also bring the same effects as those of the above-described embodiment.

Third Embodiment

Next, a third embodiment of the present invention will be explained with reference to FIGS. 3 and 4. The first embodiment is characterized in that one catalytic reacting section and one heat exchanging section temperature are serially disposed and integrated as one unit. FIG. 3 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with the third embodiment of the present invention. FIG. 4 is a schematic view showing one of the units shown in FIG. 3. The components identical or equivalent to those disclosed in the first and second embodiments are denoted by the same reference numerals and will not be explained hereinafter.

As shown in FIG. 4, a single casing 81 accommodates a single catalytic reacting section 82 and a single heat exchanging section 83 which are serially disposed so as to cooperatively constitute one unit 80. As shown in FIG. 3, the catalytic reaction heater according to the third embodiment includes a plurality of units 80 (e.g. three units 80) which are serially connected. The cooling water path (i.e. water jacket) 60 is provided so as to surround the outer periphery of these units 80. According to the arrangement of the third embodiment, assembling the manufactured components is easy. Changing the reaction amount is easily feasible by changing the total number of units to be combined.

The arrangement of the third embodiment is preferably applicable to the above-described first or second embodiment or to any other embodiment described in the following description.

Fourth Embodiment

Next, a fourth embodiment of the present invention will be explained with reference to FIG. 5. The fourth embodiment is characterized in that the fuel is separately and independently supplied into each catalytic reacting section. FIG. 5 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with the fourth embodiment of the present invention. The components identical or equivalent to those disclosed in the first to third embodiments are denoted by the same reference numerals and will not be explained hereinafter.

As shown in FIG. 5, a fuel supply path introducing the fuel from the fuel supplying section 20 is branched or bifurcated into two pathways; i.e. one pathway having a first outlet 21 opened to the upstream side of the first catalytic reacting section 41, and the other pathway having a second outlet 22 opened to the downstream side of the first heat exchanging section 51 and to the upstream side of the second catalytic reacting section 42.

According to the above-described arrangement, the fuel supplied from the fuel supplying section 20 is separately and independently introduced into respective catalytic reacting sections 41 and 42. On the other hand, all of the air supplied from the air supplying section 30 is introduced via the gas mixing portion 11 into the first catalytic reacting section 41. The entire air amount supplied from the air supplying section 30 is set so as to attain a theoretical air-fuel ratio in relation to the entire fuel amount supplied from the fuel supplying section 20.

The fourth embodiment can adopt the arrangement shown in FIG. 4. Namely, one of the catalytic reacting sections 41 and 42 and one of the heat exchanging sections 51 and 52 which are serially disposed are integrated into one casing so as to constitute each one of a plurality of units connected to each other.

Furthermore, like the second embodiment, the fourth embodiment includes the temperature sensor 71 detecting the temperature of the gas is disposed at a downstream side of the heat exchanging section 51. And, the control section 70 adjusts at least one of a supply amount of the oxygen and a circulation amount of the heating medium based on a signal of the temperature sensor 71 so that the temperature of the gas becomes equal to or lower than a pre-designated temperature.

Moreover, the supply amount of the fuel and oxygen supplied into the catalytic reacting sections 41 and 42 is set in such a manner that the supplied fuel is completely consumed upon accomplishment of the catalytic reaction in a downstream end catalytic reacting section 42. Preferably, the fuel is hydrogen.

As described above, the fourth embodiment can limit the reaction amount in the first catalytic reacting section 41 by separately and independently supplying the fuel into respective catalytic reacting sections 41 and 42. Namely, setting the excess air ratio to a higher value exceeding 1 enables the first catalytic reacting section 41 to reduce the reaction amount without increasing the SV value in the first catalytic reacting section 41 and accordingly suppress the reaction temperature to a predetermined lower temperature. Moreover, the fourth embodiment supplies all of the gas into the second catalytic reacting section 42, which surely prevents the non-reacted fuel from leaking out of the catalytic reaction heater.

Fifth Embodiment

Next, a fifth embodiment of the present invention will be explained with reference to FIG. 6. The fifth embodiment is characterized in that the air is separately and independently supplied into each catalytic reacting section. FIG. 6 is a schematic view showing an overall arrangement of a catalytic reaction heater in accordance with the fifth embodiment of the present invention. The components identical or equivalent to those disclosed in the first to fourth embodiments are denoted by the same reference numerals and will not be explained hereinafter.

As shown in FIG. 6, the catalytic reaction heater of this embodiment includes a bypass air path 31 having one end opened to the gas mixing portion 11 and the other end opened to downstream side of the first heat exchanging section 51 and to the upstream side of the second catalytic reacting section 42.

According to the above-described arrangement, the air supplied from the air supplying section 30 to the gas mixing portion 11 is introduced into the first catalytic reacting section 41. And, a part of the air supplied to the gas mixing portion 11 is introduced via the bypass air path 31 into the second catalytic reacting section 42 by bypassing both the first catalytic reacting section 41 and the first heat exchanging section 51. The entire air amount supplied from the air supplying section 30 is set so as to attain a theoretical air-fuel ratio in relation to the entire fuel amount supplied from the fuel supplying section 20.

The fifth embodiment can adopt the arrangement shown in FIG. 4. Namely, one of the catalytic reacting sections 41 and 42 and one of the heat exchanging sections 51 and 52 which are serially disposed are integrated into one casing so as to constitute each one of a plurality of units connected to each other.

Furthermore, like the second embodiment, the fifth embodiment includes the temperature sensor 71 detecting the temperature of the gas is disposed at a downstream side of the heat exchanging section 51. And, the control section 70 adjusts at least one of a supply amount of the oxygen and a circulation amount of the heating medium based on a signal of the temperature sensor 71 so that the temperature of the gas becomes equal to or lower than a pre-designated temperature.

Moreover, the supply amount of the fuel and oxygen supplied into the catalytic reacting sections 41 and 42 is set in such a manner that the supplied fuel is completely consumed upon accomplishment of the catalytic reaction in a downstream end catalytic reacting section 42. Preferably, the fuel is hydrogen.

As described above, the fifth embodiment can reduce the excess air ratio in the first catalytic reacting section 41 to a lower value smaller than 1 by separately and independently supplying the air into respective catalytic reacting sections 41 and 42, thereby suppressing the reaction amount in the first catalytic reacting section 41. Furthermore, by releasing the reaction heat to the non-reacted hydrogen, the fifth embodiment decreases the reaction temperature of the first catalytic reacting section 41 to a predetermined lower temperature. Moreover, the fifth embodiment supplies all of the gas into the second catalytic reacting section 42, which surely prevents the non-reacted fuel from leaking out of the catalytic reaction heater.

Other Embodiments

The above-described embodiments of the present invention disclose two or three sets of the catalytic reacting sections and the heat exchanging sections. However, it is possible to provide four or more sets of the catalytic reacting sections and the heat exchanging sections which are alternately and serially disposed along the flowing direction of the gas.

Furthermore, it is possible to lower the temperature of the gas flowing into the second catalytic reacting section 42 by enlarging the heat transfer surface of the first heat exchanging section 51. According to this arrangement, in suppressing the reaction temperature in the second catalytic reacting section 42 to a predetermined lower temperature, it becomes possible to set a large temperature rise obtainable in the second catalytic reacting section 42. In other words, it becomes possible to set a large reaction amount in the second or succeeding catalytic reacting section. As a result, the total number of required catalytic reacting sections can be reduced.

Furthermore, increasing the cooling water amount in the cooling water path 60 is effective in suppressing the temperature of the gas flowing into the second catalytic reacting section 42. According to this arrangement, in suppressing the reaction temperature in the second catalytic reacting section 42 to a predetermined lower temperature, it becomes possible to set a large temperature rise obtainable in the second catalytic reacting section 42.

Furthermore, controlling the cooling water amount flowing in the cooling water path 60 is effective in adjusting the temperature of the gas flowing into the second catalytic reacting section 42. Hence, in a case that the reaction amount decreases due to deterioration of the catalyst, reducing the cooling water amount is effective in avoiding excessive decrease in the temperature of the second catalytic reacting section 42 and accordingly in maintaining the second catalytic reacting section 42 at an activated temperature.

Claims

1. A catalytic reaction heater comprising: a plurality of catalytic reacting sections for generating a high-temperature gas based on a catalytic reaction of fuel and oxygen; and a plurality of heat exchanging sections for increasing the temperature of a circulating heating medium based on heat exchange between said heating medium and said gas, wherein said catalytic reacting sections and said heat exchanging sections are alternately and serially disposed along a flowing direction of said gas, and a supply amount of said fuel and oxygen supplied into an upstream end catalytic reacting section is set to a value exceeding a maximum consumable level in said upstream end catalytic reacting section.

2. The catalytic reaction heater in accordance with claim 1, wherein one of said catalytic reacting sections and one of said heat exchanging sections are serially disposed in one casing so as to constitute each one of a plurality of units connected to each other.

3. The catalytic reaction heater in accordance with claim 1, wherein a temperature sensor detecting the temperature of said gas is disposed at a downstream side of said heat exchanging section, and at least one of a supply amount of said oxygen and a circulation amount of said heating medium is adjusted based on a signal of said temperature sensor so that the temperature of said gas becomes equal to or lower than a pre-designated temperature.

4. The catalytic reaction heater in accordance with claim 1, wherein the supply amount of said fuel and oxygen supplied into said catalytic reacting sections is set in such a manner that the supplied fuel is completely consumed upon accomplishment of the catalytic reaction in a downstream end catalytic reacting section.

5. The catalytic reaction heater in accordance with claim 1, wherein said fuel is hydrogen.

6. A catalytic reaction heater comprising: a plurality of catalytic reacting section for generating a high-temperature gas based on a catalytic reaction of fuel and oxygen; and a plurality of heat exchanging sections for increasing the temperature of a circulating heating medium based on heat exchange between said heating medium and said gas, wherein said catalytic reacting sections and said heat exchanging sections are alternately and serially disposed along a flowing direction of said gas, said fuel is supplied separately to each of said plurality of catalytic reacting sections, and all of said supplied oxygen is introduced into an upstream end catalytic reacting section.

7. The catalytic reaction heater in accordance with claim 6, wherein one of said catalytic reacting sections and one of said heat exchanging sections are serially disposed in one casing so as to constitute each one of a plurality of units connected to each other.

8. The catalytic reaction heater in accordance with claim 6, wherein a temperature sensor detecting the temperature of said gas is disposed at a downstream side of said heat exchanging section, and at least one of a supply amount of said oxygen and a circulation amount of said heating medium is adjusted based on a signal of said temperature sensor so that the temperature of said gas becomes equal to or lower than a pre-designated temperature.

9. The catalytic reaction heater in accordance with claim 6, wherein a supply amount of said fuel and oxygen supplied into said catalytic reacting sections is set in such a manner that the supplied fuel is completely consumed upon accomplishment of the catalytic reaction in a downstream end catalytic reacting section.

10. The catalytic reaction heater in accordance with claim 6, wherein said fuel is hydrogen.

11. A catalytic reaction heater comprising: a plurality of catalytic reacting section for generating a high-temperature gas based on a catalytic reaction of fuel and oxygen; and a plurality of heat exchanging sections for increasing the temperature of a circulating heating medium based on heat exchange between said heating medium and said gas, wherein said catalytic reacting sections and said heat exchanging sections are alternately and serially disposed along a flowing direction of said gas, said oxygen is supplied separately to each of said plurality of catalytic reacting sections, and all of said supplied fuel is introduced into an upstream end catalytic reacting section.

12. The catalytic reaction heater in accordance with claim 11, wherein one of said catalytic reacting sections and one of said heat exchanging sections are serially disposed in one casing so as to constitute each one of a plurality of units connected to each other.

13. The catalytic reaction heater in accordance with claim 11, wherein a temperature sensor detecting the temperature of said gas is disposed at a downstream side of said heat exchanging section, and at least one of a supply amount of said oxygen and a circulation amount of said heating medium is adjusted based on a signal of said temperature sensor so that the temperature of said gas becomes equal to or lower than a pre-designated temperature.

14. The catalytic reaction heater in accordance with claim 11, wherein a supply amount of said fuel and oxygen supplied into said catalytic reacting sections is set in such a manner that the supplied fuel is completely consumed upon accomplishment of the catalytic reaction in a downstream end catalytic reacting section.

15. The catalytic reaction heater in accordance with claim 11, wherein said fuel is hydrogen.