JP4945878B2 - Hydrogen generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen generator for reforming a hydrocarbon fuel with water.
[0002]
[Prior art]
One method for producing hydrogen is a steam reforming method. This is a method of generating hydrogen by performing a steam reforming reaction between a natural gas, a hydrocarbon component such as 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 generated as a subcomponent, and therefore, a shift unit that causes a shift reaction between water and carbon monoxide is used in combination. In addition, when the steam reforming method is used as the hydrogen supply method for the polymer electrolyte fuel cell, a carbon monoxide oxidation method or a methanation method is further used after the shift section in order to further remove carbon monoxide. Provide a purification section.
[0003]
A catalyst corresponding to each reaction is provided in the reforming section, the shift section, and the purification section. Since each catalyst has a different reaction temperature, it is necessary to heat the catalyst to the reaction temperature in order to supply hydrogen stably. 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 transformation section and the purification section. Therefore, in the conventional hydrogen generator using the steam reforming method, the heat from the reforming unit, for example, the heat held in the reformed gas or the surplus heat of the heating unit provided in the reforming unit, And the structure which heats a purification | cleaning part sequentially is used in many cases.
[0004]
[Problems to be solved by the invention]
When the reaction part temperatures of the reforming part, the transformation part, and the purification part are not appropriate, hydrogen generation does not proceed effectively. For example, in the steam reforming method, water is supplied so that oxygen does not run short than an equivalent amount in which carbon atoms in the raw material react to form carbon dioxide. In order for the raw material and water to react, it is necessary that at least water exists in the state of water vapor. However, when the reforming section is at a low temperature, the reaction does not proceed even if water is supplied and stays in the apparatus. In addition, when the raw material and water are supplied after the reforming section is heated to a high temperature, there is a possibility that the catalytic body deteriorates due to heat during the heating process and the reactivity decreases. Therefore, it is necessary to supply the raw material and water at an appropriate temperature.
[0005]
Further, the gas downstream from the reforming section has a temperature higher than the heat resistance temperature of the shift section catalyst. When a gas having a temperature higher than the heat-resistant temperature is supplied, the catalyst is deteriorated and the characteristics are deteriorated. Therefore, it is necessary to cool from the reforming part to the transformation part. Further, it is an object of the hydrogen generator to sufficiently reduce the carbon monoxide concentration in the purification unit and supply hydrogen. However, it is cumbersome to measure the carbon monoxide concentration every time the device is started and to determine the start of hydrogen supply, so a simple and accurate method for detecting the normal operation state is desired. .
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, an operation method of the hydrogen generator of the present invention includes a raw material supply unit, a water supply unit, a reforming unit including a reforming catalyst body that causes the raw material and water to react, and the modified unit. A heating section for heating the porous catalyst body, a shift section having a shift catalyst body for reacting carbon monoxide and water, a gas vent path communicating the reforming section and the shift section, and the gas vent path a method of operating a first temperature detection unit and the hydrogen generating apparatus Ru comprising a, after starting the operation of the heating unit, the temperature detected by the first temperature detection unit reaches the predetermined lower limit value If the raw material supply section and the more the water supply unit reformer supply of the raw material and water started, the lower limit value, the der Rukoto wherein 100 ° C. or higher 400 ° C. or less.
[0008]
Further, the method for operating the hydrogen generator of the present invention, a gas vent route for communicating the shift converter and the reformer, a water inlet to the gas vent passage, the water inlet and said shift converter and a second temperature detection unit to the gas venting path between, so that the temperature detected by the second temperature detecting section is not scooped an upper limit value, to supply water from the water inlet Features.
[0009]
Moreover, as for the operating method of the hydrogen generator of this invention, it is desirable that the said upper limit is 500 to 250 degreeC. This is because if it is lower than this temperature, water accumulates on the downstream side and the catalyst deteriorates.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention solves the problems of conventional hydrogen generators, and controls the supply of raw materials, water, and air based on the gas temperatures from the reforming unit, the transformation unit, and the purification unit. A hydrogen apparatus capable of effectively operating a catalyst body and corresponding to a stable supply of hydrogen is provided. Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
(Embodiment 1)
FIG. 1 is a view showing a longitudinal section of an essential part of the hydrogen generator of the present invention. In FIG. 1, 1 is a reforming section provided with a reforming catalyst section 1a for a steam reforming reaction. For the reforming catalyst portion 1a, a catalyst prepared by preparing a white metal noble metal was used. 2 is a heating part of the reforming part, and in this configuration, a flame burner is used as a heating means. Reference numeral 3 denotes a shift section that stores the shift catalyst body 3a. As the shift catalyst body 3a, a catalyst containing at least copper as a component was used. Reference numeral 4 denotes a carbon monoxide purifying section, in which a white metal-based oxidation catalyst 4a is provided as a purifying catalyst. 5 is a raw material supply unit mainly composed of hydrocarbon for steam reforming reaction, 6 is a water supply unit, 7 is a gas ventilation path constituted by the reforming unit 1, the transformation unit 2 and the purification unit 3, Gas is flowed in the order of the reforming unit 1, the transformation unit 2, and the purification unit 3, and the purification unit 3 has an outlet. An air supply unit 8 supplies air to the gas ventilation path 7 between the transformation unit 2 and the purification unit 3. A first temperature detection unit 9 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 unit 3.
[0012]
Next, the operation of the apparatus when supplying hydrogen in the hydrogen generator of this embodiment will be described. The heating unit 2 is operated to heat the reforming catalyst body 1a of the reforming unit 1. A hydrocarbon component as a raw material is supplied from the raw material supply unit 5 and water is supplied from the water supply unit 6 to the reforming catalyst unit 2a to advance the steam reforming reaction. The first temperature detection unit 9 measures the gas temperature after the reforming unit 2, sets a lower limit for the temperature, and starts supplying raw material and water to the reforming unit 2 when the measured temperature exceeds the lower limit. To do. The gas after the reforming section is vented to the transformation section 3 through the gas vent path 7. The gas after the transformation unit 3 is vented to the purification unit 4 through the gas ventilation 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 transformation unit from the gas ventilation path 7 between the transformation unit 3 and the purification unit 4.
[0013]
The purpose of this hydrogen generator is to generate hydrogen stably. For that purpose, it is necessary to operate each reaction part of a reforming part, a transformation part, and a purification | cleaning part at appropriate temperature. In particular, the reforming part is a part for proceeding with the basic reaction of hydrogen generation, and the supply of raw materials and water and temperature control are important. Therefore, water is supplied so that oxygen does not run short than the equivalent amount that carbon atoms in the raw material react to form carbon dioxide.
[0014]
Further, in order for the raw material and water to react, it is necessary that at least the water exists in the state of water vapor. 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 exist sufficiently even if water is supplied, and water remains in the apparatus. If a large amount of water stays, there is a possibility of closing the gas ventilation path. 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 of the reforming section is effectively performed.
[0015]
Next, an example of the operation of the hydrogen generator in this embodiment will be shown. First, the operation when the apparatus is activated will be described. The heating unit was activated and heating of the reforming unit was started. By heating the reforming section reforming catalyst body by the heating section, the gas body in the reforming catalyst body undergoes volume expansion, and the heated gas body flows into the gas ventilation path. In the first temperature detection unit, the gas body temperature after the reforming unit reforming catalyst unit is measured. In the present embodiment, based on the measured gas temperature after the reforming unit 1 in the first temperature detection unit, the supply of the raw material and water to the reforming unit 1 is started when the temperature exceeds 100 ° C. .
[0016]
Using methane gas as a hydrocarbon component as a raw material, 2 mol or more of water was added to 1 mol of methane gas, and supplied to the reforming catalyst unit 1a of the reforming unit 1. In this embodiment, when the temperature of the first temperature detection part exceeds 100 ° C., the reforming catalyst part temperature is also 100 ° C. or higher, and it has been confirmed that the supplied water can be sufficiently evaporated. During the steady operation, the heating heat amount of the heating unit 2 was controlled so that the first temperature measurement unit temperature was about 700 ° C., and the steam reforming reaction was advanced.
[0017]
Before supplying the raw material and water, supply the inert gas such as nitrogen gas to the reforming section and start heating the reforming section, so that the reforming section catalyst body temperature can be grasped more accurately. Can do. Moreover, it can substitute for nitrogen gas etc. by using the gas body which starts raw material supply before water supply and vaporizes a raw material by heating. However, when only the raw material is sent to the reforming section, carbon deposition occurs due to the reforming section temperature, so it is necessary to supply water as quickly as possible.
[0018]
In addition, the gas temperature after the reforming unit is measured and used as a criterion for starting the supply of the raw material and water. However, the temperature of the reforming unit reforming catalyst unit may be directly measured and the temperature may be used as the criterion. In this embodiment, the first temperature detection unit temperature is 100 ° C., but it goes without saying that the temperature varies depending on the operating conditions such as the device configuration, the raw material type, the raw material and water supply ratio, and the like. Nor. Moreover, although air was supplied as a gas containing oxygen, it is not restricted to air if it is a gas containing oxygen. Moreover, although the flame burner was used as a heating part, if it is the structure which can heat a reforming catalyst, it will not restrict to this.
[0019]
(Embodiment 2)
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 the operation is substantially the same as that of the first embodiment. The description of the same part is omitted, and only the difference is described. The difference is that the water supply path 6a is provided in the gas ventilation path 7 between the reforming section 1 and the transformation section 3 from the water supply section 6, and the second temperature detection section is provided in the gas ventilation path 7 after the water supply path. This is the point.
[0020]
Next, the operation of this embodiment will be described. The operation is almost the same as in the first embodiment. The difference is that an upper limit value is provided for the temperature of the second temperature detection unit, and water is supplied from the water supply unit 6 to the gas ventilation path 7 between the reforming unit 1 and the shift unit 3 so as not to exceed the upper limit value. It is.
[0021]
In general, in the hydrogen generator, the temperature of the reforming section located upstream of the raw material flow is the highest, and the temperature of each reaction section decreases in the order of the conversion section and the purification section. Therefore, the transformation unit and the purification unit are sequentially heated by heat from the reforming unit, for example, heat held by the reformed gas or surplus heat of the heating unit provided in the reforming unit. However, since the optimum reaction temperature of each reaction part is different, it is necessary to finally control to a 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 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 with latent heat of evaporation and sensible heat, there is an advantage that the apparatus configuration necessary for cooling can be reduced as compared with the case where the gas temperature is cooled by air cooling. Moreover, since water is added to the reformed gas, the reactivity of the carbon monoxide and water shift reaction can be further improved.
[0022]
Next, an example of operation of the hydrogen generator in this embodiment will be described. A catalyst mainly composed of copper and zinc was used as the shift portion catalyst body. Since the heat-resistant temperature of this catalyst is 300 ° C., the upper limit value of the second temperature detection part temperature is set to 300 ° C. Since water is directly supplied to the gas after the reforming section, the temperature control responsiveness can be remarkably improved as compared with the temperature control configuration by air cooling. Moreover, the volume required for the temperature control configuration could be reduced to about 1/10.
[0023]
In the case of a catalyst body mainly composed of iron and chromium, the upper limit is 500 ° C. This upper limit value needs to be determined according to characteristics such as the type of catalyst body and heat resistance. Moreover, although the 2nd temperature detection part measured the temperature of the gas after a reforming part, it may measure the temperature of a shift part shift catalyst directly, and may supply water based on the temperature.
[0024]
(Embodiment 3)
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 the operation similar to that of the first embodiment is performed. The description of the same part will be omitted, and only the difference 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.
[0025]
Next, the operation of this embodiment will be described. When the apparatus 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 it is determined that the supply of hydrogen from the apparatus is started when the third temperature detection unit temperature exceeds the lower limit value.
[0026]
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 the hydrogen. The concentration of carbon monoxide in hydrogen can be measured with an analytical instrument using infrared rays. However, it is not preferable to measure the carbon monoxide concentration with an analytical instrument and determine the start-up state of the apparatus from the viewpoints of cost increase and enlargement of the apparatus.
[0027]
In the present invention, the gas temperature downstream of the purification unit is measured and a lower limit value is provided. When the temperature exceeds the lower limit value, the carbon monoxide concentration in the hydrogen gas to be supplied has decreased to a predetermined value or less, so-called normal. The present invention provides a configuration that is in an operating state and can supply hydrogen to an external device. Then, the display means that indicates the normal operation state, or the product gas discharge path that is opened during normal operation is provided in the product gas discharge unit, so that the fuel connection with the hydrogen gas supply device can be controlled safely. can do.
[0028]
Basically, when the purification unit is operated effectively, carbon monoxide can be reduced. The purifying property of the carbon monoxide of the catalyst body of the purifying part is temperature dependent. Therefore, the reduction status of carbon monoxide is judged from the gas temperature downstream of the purification unit. When a white metal catalyst is used as the catalyst of the purification unit, the carbon monoxide oxidation characteristics of the catalyst depend on the carbon monoxide concentration at the inlet, and the reactivity decreases when the carbon monoxide concentration is high. In addition, the amount of heat generated during the oxidation of carbon monoxide and hydrogen is basically determined by how much it has reacted with oxygen. When the carbon monoxide concentration at the inlet is high, the reactivity decreases, so the amount of heat generation decreases, and the gas temperature after the purification section does not rise very much.
[0029]
Next, when the shift reaction at the shift portion proceeds and the carbon monoxide concentration at the inlet is lowered, the reactivity is improved, and the gas temperature after the purification portion is increased. Since the temperature increase rate is substantially constant when the amount of air supplied to the purification unit is constant, the amount of decrease in carbon monoxide can be assumed by measuring the gas temperature. Therefore, a lower limit value is provided for the gas temperature after the purification unit, and it can be determined whether or not the operation state of the apparatus is normal based on the temperature.
[0030]
Next, an example of operation of the hydrogen generator in this embodiment will be described. A platinum catalyst was used as the purification catalyst in the purification section. In the apparatus configuration of the present embodiment, when the temperature of the third temperature measurement 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 startup state of the hydrogen generator can be determined with 100 ° C. as the lower limit. Note that the temperature of the gas after the purification section basically differs depending on the type of catalyst used, the use conditions of the catalyst, and the apparatus configuration, and therefore needs to be determined according to the conditions.
[0031]
Further, the same effect can be obtained by providing not only a catalyst having an oxidizing property in the purification unit catalyst but also a catalytic body exhibiting catalytic properties for methanating at least carbon monoxide, for example, a ruthenium catalyst in the purification unit. In this embodiment, methane is used as the hydrocarbon component of the raw material. However, natural gas, hydrocarbon components such as LPG, alcohols such as methanol, or naphtha components are generally used as raw materials for steam reforming. Can also be used.
[0032]
【Effect of the invention】
As described above, according to the configuration of the present invention, the reaction of the reforming section can be effectively advanced, and the situation where water stays in the apparatus can be prevented. In addition, the apparatus configuration required for cooling could be reduced, and the reactivity of the carbon monoxide and water shift reaction could be further improved.
[0033]
In addition, the reactivity of the reforming part at the start-up and the operability improvement of the metamorphic part at the steady state can be achieved with a relatively simple configuration.
[Brief description of the drawings]
FIG. 1 is a vertical cross-sectional view of a main part of a hydrogen generator according to a first embodiment of the present invention. FIG. 2 is a vertical cross section of a main part of a hydrogen generator according to a second embodiment of the present invention. FIG. 3 is a vertical sectional view of a hydrogen generator according to a third embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Reformation part 1a Reformation catalyst part 2 Heating part 3 Transformation part 3a Transformation catalyst body 4 Purification part 4a Purification catalyst body 5 Raw material supply part 6 Water supply part 7 Gas ventilation path 8 Air supply part 9 First temperature measurement part 10 1st Second temperature measurement unit 11 Third temperature measurement unit

Claims (3)

A raw material supply unit, a water supply unit, a reforming unit equipped with a reforming catalyst body that causes the raw material and water to react, a heating unit that heats the reforming catalyst body, and a reaction between carbon monoxide and water. a shift converter provided with the shifting catalyst body which, there by the reforming section and the gas vent path for communicating the shift converter, the first temperature detection unit and the method for operating the hydrogen generating apparatus Ru provided with said gas vent path When the temperature detected by the first temperature detection unit reaches a predetermined lower limit after starting the operation of the heating unit, the raw material is supplied from the raw material supply unit and the water supply unit to the reforming unit. and it starts supplying the water, the lower limit value, the method operating the hydrogen generating apparatus according to claim der Rukoto below 100 ° C. or higher 400 ° C.. A gas ventilation path communicating the reforming section and the transformation section; a water inlet in the gas ventilation path; a second temperature detection section in the gas ventilation path between the water inlet and the transformation section; wherein the as the temperature detected by the second temperature detecting section is not scooped the upper limit value, a method operating the hydrogen generating apparatus according to claim 1, wherein the supplying water from said water inlet. The method for operating a hydrogen generator according to claim 2 , wherein the upper limit value is 500 ° C or lower and 250 ° C or higher.

Images