JP2002154805A - Reforming reaction apparatus and reforming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the starting-up time of a reforming reaction at the time of starting-up a reforming reaction apparatus for producing hydrogen by reforming a hydrocarbon based fuel. SOLUTION: A catalytic heater 28 formed by carrying an exothermic catalyst for promoting heat generation by the catalytic combustion on a heat generating body (electric heater), a honeycomb catalyst 30 on which mainly a partial oxidation reaction occurs and a honeycomb catalyst 32 on which mainly a self-heating reforming reaction occurs are arranged in the reforming reaction apparatus 24 for forming hydrogen by the reforming reaction by the supply of the fuel, air and steam, and the supply of the fuel, air and steam and the current to the catalytic heater 28 are controlled while detecting each catalyst outlet temperature with thermocouples 29, 31 and 33 by a control unit 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reforming reactor for producing hydrogen by reforming a hydrocarbon fuel (gasoline, light oil, methanol, CNG, naphtha, etc., hereinafter referred to as raw fuel) with a catalyst. The present invention relates to a reforming system including the control system, and more particularly to a technique that hastened the start of a reforming reaction.

[0002]

2. Description of the Related Art Conventional reforming reactors include, for example,
There is one shown in FIG.
No. 5). A reforming catalyst 11 for generating hydrogen by a catalytic reaction from a reaction fluid A containing an organic compound or carbon monoxide, and a heater unit 10 capable of generating heat by energization
Are arranged in the fluid flow path 12 to constitute a reforming reaction apparatus.

As an operation method at the time of startup, first, energization is started. Heating is performed until the heater unit 10 reaches a predetermined temperature, preferably a temperature required for the steam reforming reaction, partial oxidation reaction or decomposition reaction. The temperature required for the steam reforming reaction, the partial oxidation reaction or the decomposition reaction is 500 ° C. or higher, preferably 600 ° C. or higher. The temperature of the heater unit 10 itself may be measured, or the temperature may be raised by energizing for a predetermined energizing time to reach this temperature. After the temperature is raised to this temperature, the reaction fluid starts to flow.

[0004]

However, in the method of heating the heater unit 10 until it reaches the temperature required for the steam reforming reaction, the partial oxidation reaction or the decomposition reaction as in the above-mentioned conventional apparatus, the heater unit 10 is energized. Since the heating method is used only for heating, it takes a long time until the temperature of the heater unit 10 rises, and it takes time to generate hydrogen.
It takes time for the fuel cell that is supplied with hydrogen to generate power to start generating power. As a result, there is a problem that the startability of these vehicles equipped with a power train is extremely poor.

[0005] The present invention has been made in view of such conventional problems, and a reforming reaction apparatus in which the reforming reaction is promoted to reduce the time required for hydrogen generation, and a modification including a control system therefor. It aims to provide a quality system.

[0006]

For this reason, the invention according to claim 1 comprises a reforming catalyst that generates hydrogen from a hydrocarbon-based fuel by a catalytic reaction, and a heating element that generates heat when energized. In the reforming reaction apparatus described above, the exothermic catalyst for promoting an exothermic reaction with fuel is supported on the heating element.

According to the first aspect of the present invention, when the temperature of the exothermic catalyst rises due to the energization of the heating element, an exothermic reaction with the fuel (catalytic combustion) is promoted, and the temperature is increased only by energizing the heating element. Since the temperature rise of the reforming catalyst is accelerated, the temperature at which reforming is possible is reached in a short time, and the generation of reformed gas (hydrogen) can be accelerated.

Thus, for example, the startability of a vehicle equipped with a fuel cell using a reformed gas as a raw material can be improved. Further, the invention according to claim 2 provides, from the upstream side, an exothermic catalyst supported on the heating element, a reforming catalyst that mainly promotes a partial oxidation reaction, and a reforming catalyst that mainly promotes an autothermal reforming reaction. And the catalyst are provided separately.

According to the second aspect of the invention, each reaction (catalytic combustion, partial oxidation reaction,
Since the catalysts are separately arranged in ascending order of the start temperature of the autothermal reforming reaction), each reaction can be sequentially and effectively caused. The invention according to claim 3, wherein the reforming catalyst is integrally carried on the heating element together with the exothermic catalyst.

According to the third aspect of the present invention, by supporting two types of catalysts having a heat generating function and a reforming function integrally on the heat generating element, the number of parts can be reduced and the apparatus can be made compact. The invention according to claim 4 is characterized by comprising the reforming reaction device, and a control system that controls supply of fuel, air, and water and energization of the heating element.

By providing a reforming reaction device capable of accelerating the above-mentioned reforming reaction and controlling the supply of fuel, air and water and the energization of the heating element by a control system, a reforming system having excellent startability is provided. can get. According to a fifth aspect of the present invention, there is provided a second heating element which generates heat when energized and heats water to generate steam to be supplied to the reforming reactor.

According to the fifth aspect of the present invention, in a sufficiently warmed-up state, for example, steam can be generated only by exchanging water with the reformed gas from the reforming reactor. For example, it is difficult to generate steam under cold conditions where the reforming reaction cannot be started. Then, by applying power to the second heating element to generate heat, water can be heated to generate steam.

The invention according to claim 6 is characterized in that at the time of starting,
The amount of fuel, air and water supplied to the reforming reactor is controlled according to the temperature state of the catalyst. According to the invention according to claim 6, at the time of starting, the amounts of fuel, air and water supplied to the reforming reaction device are controlled in consideration of the occurrence state of each reaction according to the temperature state of the exothermic catalyst and the reforming catalyst. By doing so, the start time of the reforming reaction can be advanced as early as possible.

Further, according to a seventh aspect of the present invention, the heating element carrying the heat generating catalyst is energized, and after the heat generating catalyst reaches a first predetermined temperature, only the fuel and the air are subjected to the first air-fuel ratio. And supplying it to the reforming reactor. Claim 7
According to the invention according to the above, after the exothermic catalyst reaches the first predetermined temperature and becomes capable of promoting the exothermic reaction with the fuel, the fuel and the air are supplied to the reforming reactor to generate the heat. The temperature rise of the reforming catalyst can be accelerated by the heat generated by the catalyst.

Further, according to the present invention, after the supply of only the fuel and the air is started, after the reforming catalyst reaches a second predetermined temperature, the supply ratio of the fuel is increased, and the second air-fuel ratio is increased. It is characterized by the following. According to the invention according to claim 8, when the temperature of the reforming catalyst rises due to the promotion of the exothermic reaction with the fuel by the exothermic catalyst, and the temperature of the reforming catalyst reaches a temperature at which the exothermic reaction occurs, the fuel supply is performed. By increasing the ratio, the exothermic reaction by the reforming catalyst is promoted, and the temperature rise can be further accelerated.

According to a ninth aspect of the present invention, after the second heating element is energized to generate steam and the reforming catalyst reaches a third predetermined temperature, the fuel, air and steam are discharged. Are supplied at a predetermined ratio. According to the ninth aspect of the present invention, as described above, steam is generated by energizing the second heating element at the time of cooling such as at the time of starting, while the temperature of the reforming catalyst rises to supply steam. When the temperature reaches the temperature at which the reforming reaction occurs, the fuel, air, and steam are supplied at a predetermined ratio to start the reforming reaction, thereby quickly shifting to autothermal reforming, which is more efficient than partial oxidation. can do.

The invention according to claim 10 is the first invention.
Is a catalyst start temperature of the exothermic catalyst. According to the tenth aspect of the present invention, the first predetermined temperature at which the supply of fuel and air to the reforming reaction device is started is set as the catalytic combustion start temperature of the exothermic catalyst, so that the heat generated by catalytic combustion can be obtained quickly. Can be.

The invention according to claim 11 is the second invention, wherein
Is a temperature at which the partial oxidation reaction of the reforming catalyst starts. According to the eleventh aspect, by setting the second predetermined temperature at which the fuel supply ratio is increased to the partial oxidation reaction start temperature of the reforming catalyst, heat generation due to the partial oxidation reaction can be obtained quickly.

The invention according to claim 12 is the third invention.
Is the autothermal reforming reaction starting temperature of the reforming catalyst. According to the twelfth aspect, the third predetermined temperature at which the supply of steam in addition to fuel and air is started is set as the autothermal reforming reaction start temperature of the reforming catalyst. Reformed gas (hydrogen)
Generation can be started earlier.

The invention according to claim 13 is the first invention.
Is set to an air-fuel ratio suitable for catalytic combustion of the exothermic catalyst. According to the thirteenth aspect, by setting the first air-fuel ratio to, for example, a stoichiometric air-fuel ratio suitable for catalytic combustion of the exothermic catalyst, the temperature of catalytic combustion can be increased.

The invention according to claim 14 is the second invention.
Is set to an air-fuel ratio suitable for the partial oxidation reaction of the reforming catalyst. According to the fourteenth aspect of the present invention, the temperature of the partial oxidation reaction can be increased by setting the second air-fuel ratio to an air-fuel ratio suitable for the partial oxidation reaction of the reforming catalyst, for example, richer than the stoichiometric air-fuel ratio. it can.

The invention according to claim 15 is characterized in that a predetermined ratio of the fuel, air and water vapor is set to a value suitable for the autothermal reforming reaction of the reforming catalyst.
According to the invention according to claim 15, by setting the ratio of fuel, air, and water vapor to a value suitable for the autothermal reforming reaction of the reforming catalyst, the generation efficiency of the reformed gas by the autothermal reforming reaction Can be increased.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a reforming system provided with a reforming reaction device according to a first embodiment of the present invention. The fuel pump 20, the air pump 21, and the water pump 22 pump the fuel, the air, and the water while controlling the flow rate according to the rotation speed. The fuel and the air are supplied directly to the fuel vaporizer 23. The water pumped from the water pump 22 exchanges heat with the reformed gas generated by the reforming reaction device 24 connected to the downstream side of the fuel vaporizer 23 through the heat exchanger 25, and is used for starting and the like. At the time of cooling, the electromagnetic valve 27 is also heated by the electric heater 26 as the second heating element and becomes steam.
And is supplied to the fuel vaporizer 23.

After the warm-up, the fuel is vaporized in the fuel vaporizer 23 mainly by the calorific value of the steam, and the fuel is vaporized.
4 is supplied. The reforming reaction device 24 has a honeycomb-type catalyst heater 2 that carries an exothermic catalyst that generates heat by energization from the upstream side and promotes heat generation by catalytic combustion.
8. Thermocouple 2 for detecting outlet temperature of catalyst heater 28
9. Honeycomb catalyst 30 that mainly promotes partial oxidation reaction, thermocouple 31 that detects outlet temperature of honeycomb catalyst 30, Honeycomb catalyst 3 that mainly promotes autothermal reforming (ATR) reaction
2, a thermocouple 3 for detecting the outlet temperature of the honeycomb catalyst 32
3 are provided.

A thermocouple 34 for detecting the temperature of steam in the passage is provided in the steam passage just below the electric heater 26. Temperature signals detected by the thermocouples 29, 31, 33, and 34 are input to the control unit 35. Next, the operation of the reforming system configured as described above will be described.

In a sufficiently warmed-up state, the fuel vaporized in the fuel vaporizer 23 mixes with air and water vapor,
In the reforming reactor 24, mainly autothermal reforming (ATR)
The reformed gas (hydrogen) is generated by the honeycomb catalyst 32 that promotes the reaction. That is, a sufficient reformed gas can be obtained without performing special control by the control unit 35.

On the other hand, when the honeycomb catalyst 32 has not reached the reaction temperature of the autothermal reforming, such as at the time of starting, at the time of cooling,
The control unit 35 energizes the electric heater 26 to promote the generation of water vapor, and based on the temperature signals from the thermocouples 29, 31, 33, and 34, the catalyst heater 28 in the reforming reaction device 24. And control the supply of fuel, air and water.

Hereinafter, the control at the time of starting the reforming system will be described with time based on the time chart shown in FIG. The ignition switch is turned on (S
1) At the same time, the electric heater 26 and the catalyst heater 28 are energized (S2) to promote the generation of water vapor and to generate heat to increase the temperature of the catalyst heater 28.

The catalyst heater 2 detected by the thermocouple 29
When the outlet temperature of No. 8 reaches the first predetermined temperature T1,
It is determined that catalytic combustion by the exothermic catalyst of the catalyst heater 28 is possible (S3). Based on the determination, the fuel pump 20 and the air pump 21 are driven, and their rotational speeds are controlled to supply fuel and air at the stoichiometric air-fuel ratio (S4). Solenoid valve 27
Is kept in a valve-closed state with the power supply turned off, and no steam is supplied. Thereby, in the catalyst heater 28, catalytic combustion is caused by the mixture of the supplied fuel and air.
The reaction formula of catalytic combustion when isooctane is used as a fuel is shown below.

C ₈ H ₁₈ + 12.5O ₂ → 9H ₂ O + 8CO ₂ (Exothermic Reaction) When the outlet temperature of the honeycomb catalyst 30 detected by the thermocouple 31 reaches the second predetermined temperature T2 (> T1) ,
It is determined that the partial oxidation reaction in the honeycomb catalyst 30 is possible (S5). Based on the determination, the rotational speeds of the fuel pump 20 and the air pump 21 are controlled to increase the fuel supply ratio, and the fuel is supplied at a rich air-fuel ratio (S6). Thereby, the partial oxidation reaction is started by the honeycomb catalyst 30. Similarly, the reaction formula for partial oxidation when isooctane is used as the fuel is shown below.

C ₈ H ₁₈ + 8O ₂ → 9H ₂ + 8CO ₂ (exothermic reaction) Further, with the start of the partial oxidation reaction, the catalyst heater 2
8 is stopped. That is, since the heat generated by the catalyst heater 28 is used to accelerate the start of the partial oxidation reaction in the honeycomb catalyst 30, the power supply is stopped after the start of the partial oxidation reaction to save power consumption.

It is determined that the steam temperature detected by the thermocouple 34 has reached a temperature at which fuel vaporization can be performed (S
7). From this time, the amount of current supplied to the electric heater 26 is gradually reduced, and finally, the current supply is stopped. When the outlet temperature of the honeycomb catalyst 32 detected by the thermocouple 33 reaches the third predetermined temperature T3 (> T2), it is determined that the self-thermal reforming (ATR) by the honeycomb catalyst 32 is possible ( S8).

When the solenoid valve 27 is energized and opened,
The water pump 22 is driven to supply steam while controlling the rotation speed and the flow rate (S9). Thereby, the fuel is vaporized by the steam in the fuel vaporizer 23,
A self-thermal reforming reaction occurs in the honeycomb catalyst 32 to generate a reformed gas (hydrogen). Here, the reforming reaction when the fuel is isooctane is as in the steam reforming reaction described below, and the amount of heat required in the endothermic reaction is mainly based on the honeycomb catalyst 30 without externally supplying the same. Since it is covered by the heat generated by the partial oxidation, a self-thermal reforming reaction occurs.

C ₈ H ₁₈ + 16H ₂ O → 17H ₂ + 8CO ₂ (Endothermic Reaction) As described above, by promoting heat generation by the catalyst heater 28 supporting the exothermic catalyst, the honeycomb catalyst 30 starts the partial oxidation reaction. As a result, the honeycomb catalyst 32 which mainly promotes the autothermal reforming (ATR) can reach the predetermined temperature required for the reaction in a short time.

As a result, for example, the startability of a vehicle equipped with a fuel cell using the reformed gas (hydrogen) from the reforming reaction device as a raw material can be significantly improved. In the first embodiment, the catalysts are separated and arranged in the reforming reaction apparatus in order from the starting temperature of each reaction (catalytic reaction, partial oxidation reaction, autothermal reforming reaction) from the upstream side. Each reaction can be sequentially and effectively generated.

FIG. 3 shows a reforming system provided with a reforming reactor according to a second embodiment of the present invention. The reforming reaction device 41 according to the second embodiment includes a catalyst heater that supports an exothermic catalyst that promotes heat generation by catalytic combustion in the first embodiment, a honeycomb catalyst that mainly promotes partial oxidation, And a three-function integrated catalyst 42 (in which the exothermic catalyst and the reforming catalyst are supported on a common heating element), and a downstream thereof. 1 for detecting catalyst outlet temperature
And a plurality of thermocouples 43. Other configurations are the same as those of the first embodiment.

In the second embodiment, the temperature of each catalyst outlet is detected by each thermocouple 31, 33, 34 in the first embodiment.
Is detected in the same manner, and the same control is performed. That is, as shown in the time chart of FIG.
Above the predetermined temperature, catalytic combustion by the exothermic catalyst is started. When the exothermic reaction is accelerated by the catalytic combustion and becomes equal to or higher than the second predetermined temperature, a partial oxidation reaction is started. Catalyst 4
The energization of the heater built in 2 is stopped. When the temperature further rises to a third predetermined temperature or more due to the heat generated by the partial oxidation reaction, the supply of steam is started to generate a reformed gas by the self-thermal reforming reaction.

Therefore, the same effect as that of the first embodiment can be obtained, and the number of parts is reduced, and the size is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a reforming system including a reforming reaction device according to a first embodiment of the present invention.

FIG. 2 is a time chart showing control at the time of starting according to the first embodiment;

FIG. 3 is a diagram showing a configuration of a reforming system including a reforming reaction device according to a second embodiment of the present invention.

FIG. 4 is a time chart showing control at the time of starting according to the second embodiment;

FIG. 5 is a diagram showing a conventional example of a reforming reaction apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 20 fuel pump 21 air pump 22 water pump 24 reforming reaction device 26 electric heater 28 catalytic heater 29 thermocouple 30 honeycomb catalyst 31 thermocouple 32 honeycomb catalyst 33 thermocouple 34 thermocouple 35 control unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhiko Ishiwatari 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Inside Nissan Motor Co., Ltd. (72) Inventor Takashi Aoyama 2 Takara-cho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Nissan Motor Co., Ltd. Terms (reference) 4G040 EA02 EA03 EA06 EA07 EB03 EB12 EB13 EB18 EB23 EB41 EB43 4G140 EA02 EA03 EA06 EA07 EB03 EB12 EB13 EB18 EB23 EB41 EB43 5H027 AA02 BA01 KK42 MM12 MM21

Claims (15)

[Claims] 1. A reforming catalyst that generates hydrogen from a hydrocarbon fuel by a catalytic reaction, a heating element that generates heat when energized,
Wherein the exothermic catalyst for promoting an exothermic reaction with fuel is carried on the heating element. 2. An exothermic catalyst supported on the heating element, a reforming catalyst that mainly promotes a partial oxidation reaction, and a reforming catalyst that mainly promotes a self-thermal reforming reaction are: 2. The reforming reaction device according to claim 1, wherein the reforming reaction device is provided separately. 3. The reforming reaction apparatus according to claim 1, wherein the reforming catalyst is integrally carried on the heating element together with the exothermic catalyst. 4. A reforming reactor according to any one of claims 1 to 3, and a control system for controlling supply of fuel, air, and water and energization of the heating element. A reforming system, characterized in that: 5. The reforming system according to claim 4, further comprising a second heating element that generates heat when energized, heats water, and generates steam to be supplied to the reforming reaction device. 6. The reforming system according to claim 4, wherein the amount of fuel, air and water to be supplied to the reforming reaction device is controlled at the time of starting according to the temperature state of the catalyst. . 7. A heating element carrying said exothermic catalyst is energized, and after said exothermic catalyst reaches a first predetermined temperature, only fuel and air are supplied to said reforming reactor at a first air-fuel ratio. The reforming system according to claim 6, wherein: 8. After the supply of only the fuel and air is started, after the reforming catalyst reaches a second predetermined temperature, the fuel supply ratio is increased to a second air-fuel ratio. Item 8. A reforming system according to Item 7. 9. After the second heating element is energized to generate steam, and after the reforming catalyst reaches a third predetermined temperature, fuel, air and steam are supplied at a predetermined ratio. The reforming system according to any one of claims 6 to 8, wherein: 10. The reforming system according to claim 7, wherein the first predetermined temperature is a catalytic combustion start temperature of the exothermic catalyst. 11. The temperature according to claim 8, wherein the second predetermined temperature is a temperature at which a partial oxidation reaction of the reforming catalyst starts.
The reforming system according to claim 10. 12. The reforming system according to claim 9, wherein the third predetermined temperature is a temperature at which the reforming catalyst starts an autothermal reforming reaction. . 13. The reforming apparatus according to claim 7, wherein said first air-fuel ratio is set to an air-fuel ratio suitable for catalytic combustion of said exothermic catalyst. system. 14. The air-fuel ratio according to claim 8, wherein the second air-fuel ratio is set to an air-fuel ratio suitable for a partial oxidation reaction of the reforming catalyst. Reforming system. 15. The method according to claim 9, wherein the predetermined ratio of the fuel, air and steam is set to a value suitable for the autothermal reforming reaction of the reforming catalyst. A reforming system according to any one of the preceding claims.