JP3415086B2 - Hydrogen generator - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hydrogen generator for reforming a hydrocarbon fuel with water.

[0002]

2. Description of the Related Art One of the methods for producing hydrogen is the steam reforming method. It is a method of producing hydrogen by causing a steam reforming reaction of a hydrocarbon component such as natural gas and LPG, an alcohol such as methanol, or an organic compound raw material such as a naphtha component and water in a reforming section provided with a reforming catalyst. . In this steam reforming reaction, carbon monoxide is produced as an accessory component, so a shift conversion section for shifting the reaction between water and carbon monoxide is also used. In addition, when using the steam reforming method as a hydrogen supply method for a polymer electrolyte fuel cell, in order to further remove carbon monoxide, a carbon monoxide oxidation method or a methanation method is further used after the shift conversion section. There will be a purification unit.

A catalyst corresponding to each reaction is provided in the reforming section, shift conversion section and purification section. Since the respective catalysts have different reaction temperatures, it is necessary to heat the catalysts to the reaction temperature in order to stably supply hydrogen. The reaction temperature is highest in the reforming section located upstream of the raw material flow, and the temperature decreases in the order of the shift conversion section and the purification section. Therefore, in the hydrogen generator using the conventional steam reforming method, the heat from the reforming unit, for example, the heat held by the reformed gas or the surplus heat of the heating unit provided in the reforming unit, is used. In addition, a configuration in which the purifying section is sequentially heated is often used.

[0004]

If the temperature of each reaction section of the reforming section, the shift conversion section and the purification section is not appropriate, hydrogen generation does not proceed effectively. For example, in the steam reforming method, water is supplied so that oxygen does not become less than the equivalent amount of carbon atoms in the raw material to react with each other to form carbon dioxide. In order for the raw material to react with water, it is necessary that at least water exists in the state of steam. However, when the temperature of the reforming section is low, the reaction does not proceed even when water is supplied and the reaction stays in the apparatus. Further, when the raw material and water are supplied after the reforming section is heated to a high temperature, the catalyst may deteriorate due to heat during the heating process and the reactivity may decrease. Therefore, it is necessary to supply the raw material and water at an appropriate temperature.

Further, the temperature of the gas downstream of the reforming section becomes higher than the heat resistant temperature of the shift section catalyst. If a gas with a temperature higher than the heat-resistant temperature is supplied, the catalyst will deteriorate and the characteristics will deteriorate.
It is necessary to cool from the reforming section to the shift conversion section. Further, it is the purpose of the hydrogen generator to sufficiently reduce the carbon monoxide concentration in the purifying unit and supply hydrogen. However, since it is complicated to measure the carbon monoxide concentration at each device start-up and determine the start of hydrogen supply, a simple and accurate method for detecting the normal operation state is desired. .

[0006]

In order to solve the above-mentioned problems, the hydrogen generator of the present invention comprises a raw material supply section, a water supply section, an air supply section, and a reforming catalyst for reacting the raw material with water. A reforming section provided with a medium; a heating section for heating the reforming catalyst body; a shift section having a shift catalyst body for reacting carbon monoxide with water; and a purification catalyst body for oxidizing carbon monoxide. The purifying unit provided, the generated gas discharging unit that discharges the generated gas that has passed through the purifying unit, the raw material supply unit, the reforming unit, the shift conversion unit, the purifying unit, and the generated gas discharging unit are in communication. In a hydrogen generator that supplies air from the air supply unit to the gas ventilation path that connects the shift conversion section and the purification section with a gas ventilation path as a constituent element, the reforming section and the shift conversion section communicate with each other. A first temperature detection unit is provided in the gas ventilation path, After starting the operation of the thermal unit, when the temperature of the first temperature detection unit reaches the predetermined lower limit value, when starting the supply of the raw material and water to the reformer together
And a gas ventilation path that connects the purification unit and the generated gas discharge unit.
The third temperature detector is arranged in the
The lower limit value is set in the
The above is characterized in that it is judged to be in a normal operation state .

At this time, the lower limit of the first temperature detector is 1
It is desirable that the temperature is from 00 ° C to 400 ° C. This is because when the temperature is higher than this temperature, carbon precipitation occurs.

[0008] In addition, a water inlet is provided in a gas passage that connects the reforming section and the shift section, and the water inlet is provided between the water inlet and the shift section.
Of a second temperature detector provided in the gas vent passage defines an upper limit to the temperature of the second temperature <br/> degree detecting unit, so that the temperature of the second temperature detecting section is not scooped the upper limit value In addition, water is supplied to the gas ventilation path.

At this time, it is desirable that the upper limit of the temperature of the second temperature detecting portion is 500 ° C. or less and 250 ° C. or more.
This is because if the temperature is lower than this temperature, water will be accumulated on the downstream side to deteriorate the catalyst.

[0010]

At this time, the lower limit of the temperature of the third detector is 1
It is desirable that the temperature is from 00 ° C to 500 ° C.

Further, it is characterized in that display means for indicating a normal operation state or a generated gas discharge path which is opened during a normal operation is provided in the generated gas discharge part.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention solves the problems of the conventional hydrogen generator, and supplies the raw materials, water and air based on the gas temperatures from the reforming section, shift conversion section and purification section. It is intended to provide a hydrogen device that can control and effectively operate the catalyst body in each reaction part and can stably supply hydrogen. Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing a vertical cross section of a main part of a hydrogen generator of the present invention. In FIG.
Reference numeral 1 is a reforming section provided with a reforming catalyst section 1a for steam reforming reaction. For the reforming catalyst section 1a, a catalyst prepared by preparing a white metal-based noble metal was used. Reference numeral 2 is a heating section of the reforming section, and in this configuration, a flame burner is used as the heating means. Reference numeral 3 denotes a shift conversion unit in which the shift conversion catalyst body 3a is housed. A catalyst containing at least copper as a component was used for the shift catalyst body 3a. Reference numeral 4 is a carbon monoxide purification unit, which is a white metal based oxidation catalyst 4a as a purification catalyst.
Is provided. Reference numeral 5 is a raw material supply section containing hydrocarbon as a main component for the steam reforming reaction, and 6 is a water supply section.
Is a gas ventilation path composed of the reforming section 1, the shift conversion section 2 and the purification section 3, and has a gas flow in the order of the reforming section 1, the shift conversion section 2 and the purification section 3, and has an outlet in the purification section 3. Further, 8 is an air supply unit that supplies air to the gas ventilation path 7 between the shift conversion unit 2 and the purification unit 3. Reference numeral 9 denotes a first temperature detection unit that detects the gas temperature after the reforming unit 1, and is provided in the gas ventilation path 7 between the reforming unit 1 and the shift conversion unit 3.

Next, in the hydrogen generator of this embodiment,
The operation of the apparatus when supplying hydrogen will be described. The heating unit 2 is operated to heat the reforming catalyst body 1a of the reforming unit 1. The raw material hydrocarbon component is supplied from the raw material supply unit 5, and the water is supplied to the water supply unit 6
Is supplied to the reforming catalyst section 2a from which the steam reforming reaction proceeds. The gas temperature after the reforming section 2 is measured by the first temperature detecting section 9 and a lower limit value is set for the temperature, and when the measured temperature exceeds the lower limit value, the supply of the raw material and water to the reforming section 2 is started. To do. The gas after the reforming section is vented to the shift conversion section 3 through the gas vent path 7. The gas after the metamorphic section 3 is vented to the purifying section 4 through the gas vent path 7. The gas after the purification unit 4 is supplied to the outside through the gas ventilation path 7. At this time, air is supplied from the air supply unit 8 to the gas after the conversion unit from the gas ventilation path 7 between the conversion unit 3 and the purification unit 4.

The purpose of this hydrogen generator is to stably generate hydrogen. For that purpose, it is necessary to operate each reaction section of the reforming section, the shift conversion section, and the purification section at an appropriate temperature. Particularly, the reforming section is a section that promotes the basic reaction of hydrogen generation, and it is important to control the supply amount of raw materials and water and the temperature. Therefore, water is supplied so that oxygen does not become less than the equivalent amount of carbon atoms in the raw material to react to form carbon dioxide.

Further, in order for the raw material and water to react with each other, it is necessary that at least water exists in the state of steam.
However, when the reforming section is at a low temperature immediately after the start of the apparatus, the reaction does not proceed because water does not sufficiently exist as steam even when water is supplied, and water remains in the apparatus. If a large amount of water is retained, the gas ventilation path may be blocked. Therefore, in the present invention, the gas temperature after the reforming section is measured, and the raw material and water are supplied based on the temperature. With this configuration, water is sufficiently evaporated and the reaction in the reforming section is effectively performed.

Next, an operation example of the hydrogen generator in the present embodiment will be shown. First, the operation at the time of starting the device will be described. The heating section was activated to start heating the reforming section. By heating the reforming part reforming catalyst body by the heating part, the gas body in the reforming catalyst body expands in volume, and the heated gas body flows into the gas ventilation path. The first temperature detecting section measures the temperature of the gas body after the reforming section and the reforming catalyst section. In the present embodiment, based on the gas temperature measurement value after the reforming unit 1 in the first temperature detecting unit, the temperature exceeds 100 ° C., so that the supply of the raw material and water to the reforming unit 1 is started. .

Methane gas was used as a hydrocarbon component as a raw material, and 2 mol or more of water was added to 1 mol of methane gas and the water was supplied to the reforming catalyst section 1a of the reforming section 1. In the present embodiment, when the temperature of the first temperature detection part exceeds 100 ° C., the temperature of the reforming catalyst part also becomes 100 ° C. or higher, and it was confirmed that the supplied water can be sufficiently evaporated. During the steady operation, the heating calorie of the heating unit 2 was controlled so that the temperature of the first temperature measuring unit was about 700 ° C., and the steam reforming reaction was allowed to proceed.

By supplying an inert gas such as nitrogen gas to the reforming section and starting heating of the reforming section before supplying the raw material and water, the temperature of the reforming section catalyst can be more accurately measured. You can figure it out. Also, start the raw material supply before the water supply,
By using a gas that vaporizes the raw material by heating, nitrogen gas or the like can be substituted. However, when only the raw materials are sent to the reforming section, carbon precipitation occurs due to the temperature of the reforming section, so that it is necessary to supply water as soon as possible.

Further, the gas temperature after the reforming section was measured and used as the criterion for starting the supply of the raw material and water, but the temperature of the reforming catalyst section for the reforming section was directly measured and the temperature was also used as the criterion. Good. In the present embodiment, the first temperature detection unit temperature is 100 ° C. as a reference, but it goes without saying that the temperature may also differ due to differences in operating conditions such as the device configuration, raw material species, and raw material / water supply ratio. Nor. Although air is supplied as a gas containing oxygen, the gas is not limited to air as long as it is a gas containing oxygen. Although the flame burner is used as the heating unit, the present invention is not limited to this as long as the reforming catalyst can be heated.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention. The configuration is almost the same as that of the first embodiment shown in FIG. 1, and an operation similar to that of the first embodiment is performed.
Descriptions of the same parts will be omitted, and only the differences will be described. The difference is that the water supply path 6a is provided between the water supply section 6 and the gas ventilation path 7 between the reforming section 1 and the shift conversion section 3, and
The second temperature detecting unit is provided in the gas ventilation path 7 after the water supply path.

Next, the operation of this embodiment will be described.
The operation is almost the same as that of the first embodiment. The difference is that an upper limit value is set for the second temperature detection unit temperature, and water is supplied from the water supply unit 6 to the gas ventilation path 7 between the reforming unit 1 and the shift conversion unit 3 so as not to exceed the upper limit value. Is.

In the hydrogen generator, the temperature of the reforming section located upstream of the raw material flow is generally highest, and the temperature of each reaction section is lowered in the order of the shift conversion section and the purification section. Therefore, heat from the reforming section,
For example, the shift section and the purification section are sequentially heated by the heat possessed by the reformed gas or the surplus heat of the heating section provided in the reforming section. However, since the optimum reaction temperature of each reaction part is different, it is necessary to finally control the temperature suitable for the catalytic reaction of each reaction part. In the present embodiment, a configuration is shown in which the gas temperature entering the shift conversion section is controlled, and water is supplied to the gas after the reforming section to control the gas temperature. By directly supplying water and cooling it by the latent heat of evaporation or sensible heat, there is an advantage that the device configuration required for cooling can be made smaller than in the case of cooling the gas temperature by air cooling. Further, since water is added to the reformed gas, the reactivity of the carbon monoxide / water conversion reaction can be further improved.

Next, an operation example of the hydrogen generator in the present embodiment will be shown. A catalyst containing copper and zinc as main components was used as the metamorphic catalyst. The heat resistant temperature of this catalyst is 30
Since it is 0 ° C., the upper limit of the second temperature detection unit temperature is set to 3
It was set to 00 ° C. Since water is directly supplied to the gas after the reforming section,
The responsiveness of temperature control could be improved significantly compared to the temperature control configuration by air cooling. Also, the volume required for the temperature control configuration could be reduced to about 1/10.

In the case of a catalyst body containing iron and chromium as main components, the upper limit is 500 ° C. It is necessary to determine this upper limit value depending on the type of catalyst and heat resistance. Further, the second temperature detection unit measures the temperature of the gas after the reforming unit, but may directly measure the temperature of the shift conversion catalyst and supply water based on the temperature.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention. The configuration is almost the same as that of the first embodiment shown in FIG. 1, and an operation similar to that of the first embodiment is performed. Description of the same parts will be omitted, and only the differences will be described. The difference is that the third temperature detection unit 11 is provided in the gas ventilation path 7 after the purification unit 4.
That is the point.

Next, the operation of this embodiment will be described.
When the device is activated, the same operation as in the first embodiment is performed. The difference is that a lower limit value is set for the third temperature detection unit temperature, and when the third temperature detection unit temperature exceeds the lower limit value, it is determined to start hydrogen supply from the device.

When the hydrogen generator of the present invention is used as a device for supplying hydrogen to a fuel cell, particularly a polymer electrolyte fuel cell, it is necessary to reduce and supply carbon monoxide in hydrogen. The concentration of carbon monoxide in hydrogen can be measured with an analytical instrument or the like using infrared rays. However, it is not preferable to measure the carbon monoxide concentration with an analytical instrument and judge the starting state of the device from the viewpoint of cost increase and size increase of the device.

In the present invention, the gas temperature downstream of the purifying unit is measured and a lower limit value is set, and the temperature exceeds the lower limit value, whereby the carbon monoxide concentration in the hydrogen gas to be supplied falls below a predetermined value. In the so-called normal operation state, hydrogen is supplied to an external device. Then, by providing a display means indicating the normal operation state or a generated gas discharge path which is opened during the normal operation in the generated gas discharge part, the fuel connection with the hydrogen gas supply target device can be safely controlled. can do.

Basically, when the purifying section is operated effectively, carbon monoxide can be reduced. The carbon monoxide purification performance of the catalyst body of the purification unit depends on temperature. Therefore, the state of carbon monoxide reduction is judged from the gas temperature downstream of the purification unit. When a white metal-based catalyst is used as the catalyst of the purification unit, the carbon monoxide oxidation characteristics of the catalyst depend on the inlet carbon monoxide concentration, and the reactivity decreases when the carbon monoxide concentration is high. Further, the amount of heat generated during the oxidation of carbon monoxide and hydrogen is basically determined by how much it reacts with oxygen. When the carbon monoxide concentration at the inlet is high, the reactivity decreases, so the amount of heat generated decreases and the gas temperature after the purification section does not rise so much.

Next, when the shift reaction in the shift conversion section progresses and the carbon monoxide concentration at the inlet becomes low, the reactivity is improved, and the gas temperature after the purification section rises. Since the rate of temperature increase is almost constant when the amount of air supplied to the purification unit is constant, the amount of decrease in carbon monoxide can be estimated by measuring the gas temperature. Therefore, it is possible to set a lower limit value for the gas temperature after the purifying unit and determine whether the operating state of the device is normal based on the lower limit value.

Next, an operation example of the hydrogen generator in the present embodiment will be shown. A platinum catalyst was used as the purification catalyst in the purification section. In the device configuration of the present embodiment, when the temperature of the third temperature measuring unit was 100 ° C. or higher, the carbon monoxide concentration in the gas after the purification unit could be stably reduced to 20 ppm or less. Therefore, it can be said that the starting state of the hydrogen generator can be determined with 100 ° C. as the lower limit value. The temperature of the gas after the purifying section basically differs depending on the type of catalyst used, the usage conditions of the catalyst, and the apparatus configuration, and therefore it must be determined in accordance with the conditions.

The same effect can be obtained by providing not only a catalyst having an oxidizing property but also a catalytic body having a catalytic property for methanating at least carbon monoxide, for example, a ruthenium catalyst, in the purifying part in the purifying part. It was Although methane is used as the hydrocarbon component of the raw material in the present embodiment, it is generally used as a raw material for steam reforming such as natural gas, hydrocarbon component such as LPG, alcohol such as methanol, or naphtha component. Can also be used.

[0035]

As described above, according to the configuration of the present invention, the reaction in the reforming section can be effectively advanced, and the situation in which water stays in the apparatus can be prevented. In addition, the device configuration required for cooling can be reduced, and the reactivity of the carbon monoxide / water conversion reaction can be further improved.

Further, it was possible to secure the reactivity of the reforming section at startup, improve the operability of the shift section at steady state, and determine the startup state of the hydrogen generator with a relatively simple structure.

[Brief description of drawings]

FIG. 1 is a view showing a vertical cross section of a main part of a hydrogen generator according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the essential parts of a hydrogen generator according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a hydrogen generator according to a third embodiment of the present invention.

[Explanation of symbols]

1 reformer 1a Reforming catalyst section 2 heating section 3 metamorphosis department 3a Metamorphic catalyst 4 Purification Department 4a Purification catalyst body 5 Raw material supply department 6 Water supply section 7 gas ventilation paths 8 Air supply section 9 First temperature measuring unit 10 Second temperature measuring unit 11 Third temperature measuring unit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kiyoshi Taguchi Kiyoshi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Toshiyuki Shono 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Koichiro Kitagawa No. 6-2 61, Imafuku Nishi, Joto-ku, Osaka City, Osaka Prefecture Matsushita Seiko Co., Ltd. (56) Reference JP-A-11-149931 (JP, A) JP-A-10-64570 ( JP, A) Patent 137281 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) C01B 3/38

Claims (6)

(57) [Claims] 1. A raw material supply section, a water supply section, an air supply section, a reforming section having a reforming catalyst body for reacting the raw material with water, and a heating section for heating the reforming catalyst body. A shift conversion section including a shift catalyst body for reacting carbon monoxide and water; a purification section including a purification catalyst body that oxidizes carbon monoxide; and a generated gas that discharges the generated gas that has passed through the purification section. A discharge part, a gas supply path that connects the raw material supply part, the reforming part, the shift conversion part, the purification part, and the generated gas discharge part are components, and the shift conversion part and the purification part are communicated with each other. In the hydrogen generator that supplies air from the air supply unit to the gas ventilation path, a first temperature detection unit is provided in the gas ventilation path that connects the reforming unit and the shift conversion unit, and the operation of the heating unit is performed. After starting, the temperature of the first temperature detection unit is predetermined When the lower limit value is reached, supply of raw material and water to the reforming section is started , and the purification section and raw
Third temperature detection in the gas vent passage that communicates with the product gas outlet
Section, and set the lower limit for the temperature of the third temperature detection section.
Therefore, when the temperature of the third temperature detection unit is above the lower limit value, normal
A hydrogen generator characterized by being judged to be in an operating state . 2. The hydrogen generator according to claim 1, wherein the lower limit value of the first temperature detection unit is 100 ° C. or higher and 400 ° C. or lower. 3. A water inlet in a gas vent passage communicating between the reforming section and the shift section, and a gas between the water inlet and the shift section.
A second temperature detector provided in the scan vent passage defines an upper limit to the temperature of the second temperature detector, so that the temperature of the second temperature detecting section is not scooped the upper limit value, the gas vent passage The hydrogen generator according to claim 1, wherein water is supplied to the hydrogen generator. 4. The upper limit of the temperature of the second temperature detector is 50.
4. The temperature is 0 ° C. or lower and 250 ° C. or higher.
The hydrogen generator described. 5. The hydrogen generator according to claim 1 , wherein the lower limit of the temperature of the third detector is 100 ° C. or higher and 500 ° C. or lower. Display means indicating that wherein a normal operating state or, claim 1 also <br/> 5, characterized in that a product gas discharge path to open during normal operation to generate gas discharge portion, The hydrogen generator described.