JP2001199702A - Apparatus for hydrogen generation, method of operation thereof and fuel cell system using the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that it takes long time before the temperature of the catalyst in a cleaning section reaches the active temperature since condensed water accumulates in a pass way and heat is required for vaporizing the accumulated condensed water when the operation is stopped in a short time after the start of the operation and thereafter the operation is restarted in a hydrogen generation apparatus comprising a reforming section, a degeneration section and the cleaning section. SOLUTION: A discharging port for the condensed water is formed in the pass way of the generated gas, and the condensed water is discharged from the port. Further, the open motion of the shut-off valve is limited in a specific time to prevent the discharge of hydrogen gas in the middle way of the generation. The motion of the shut-off valve is synchronized with the operation for the purge inside the pass way for the generated gas by an inert gas, which is performed before start-up, so that the condensed water in the pass way is surely discharged through the pushing out to the discharging port for the condensed water with high pressure in the purge before start-up. The effluent which is discharged from the discharging port for the condensed water is led to a recovery section for condensed water recovered from the discharge gas of a polymer electrolyte type fuel cell, and the effluent is recovered without draining outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to natural gas, LP
The present invention relates to a device that generates hydrogen to be supplied to a hydrogen utilization device such as a fuel cell, using a hydrocarbon-based substance such as G, gasoline, naphtha, kerosene, and methanol, water and air as raw materials.

[0002]

2. Description of the Related Art Hydrogen has attracted attention as one of the promising energy sources to replace fossil fuels, but it is necessary to improve social infrastructure such as hydrogen pipelines for its effective use. One way is to use natural gas,
In addition, a method of generating hydrogen by reforming the fuel at a place where hydrogen is needed by utilizing the already established transportation and transportation infrastructure such as fossil fuel and alcohol is being studied.

For example, various on-site power generators for small and medium-scale applications include natural gas (city gas) reforming technology for fuel cells and methanol reforming technology for fuel cells for automobile power sources. Proposed in form. In order to generate hydrogen by reforming these raw materials, a catalytic reaction at a high temperature is used, and typical methods include a steam reforming method and an autothermal method using partial oxidation in combination.

However, since the reforming reaction proceeds at a high temperature, along with hydrogen as a product, carbon monoxide (hereinafter referred to as CO) and carbon dioxide (hereinafter referred to as CO2) are produced as by-products from the reaction equilibrium. . When applying the generated hydrogen to a fuel cell, especially in a polymer electrolyte fuel cell, the by-product CO poisons the electrode of the fuel cell and significantly degrades its performance. Need to be kept. Therefore, it is common to employ a method of adding a shift reaction section and a CO purification section downstream of the reforming reaction section to reduce the CO concentration to several tens of ppm. In this series of reactions, the C concentration of about 10% generated in the reforming section
O is reduced to about 1% in the shift section, and further reduced to several tens ppm in the CO purification section, and supplied to the fuel cell.

[0005]

A hydrogen generator for supplying hydrogen to a fuel cell, particularly a polymer electrolyte fuel cell, comprises a reforming reaction, a shift reaction,
It is common to go through a purification reaction. The general catalyst temperature in each reaction is 650 to 750 ° C. in the reforming section, 200 to 350 ° C. in the denaturing section, and 100 to 200 ° C. in the purifying section. Since it cannot be reduced to tens of ppm, it cannot be connected to a fuel cell.

Accordingly, the start-up time of the fuel cell is limited by the rise time of the catalyst temperature in the purifying section. In the denaturing section, the catalyst reaches the activation temperature by the waste heat after the end of the reforming reaction, and starts the reaction. Further, the CO purifying section reaches the activation temperature by the waste heat after the end of the denaturation reaction and starts the reaction. However, in this configuration, depending on the operation method, condensed water during the generation of hydrogen gas may accumulate in the passage, and the rise time of the catalyst temperature may be delayed.

For example, when the operation is stopped for a short time after the start of operation, when the temperatures of the reforming section and the purifying section are not sufficiently increased, the gas reformed in the reforming section (hereinafter referred to as reformed gas). ), And then the gas modified in the modification section (hereinafter, referred to as
Water (denatured gas) is condensed and condensed water accumulates in the lower part of the purification unit. When the operation is restarted in that state, since heat is required to evaporate the accumulated condensed water, it takes a long time to raise the temperature of the purification catalyst to the activation temperature.

The present invention has been made in view of these points, and has as its object to reduce the time required to reach the catalyst activation temperature of the purifying section.

[0009]

In order to solve the above-mentioned problems, a hydrogen generator of the present invention has 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 having a medium, a shift section having a shift catalyst for reacting carbon monoxide with water, a shift section having a shift catalytic body for oxidizing carbon monoxide, and passing through the shift section. A hydrogen generation apparatus including a product gas discharge unit that discharges product gas, and a gas ventilation path that communicates the raw material supply unit, the reforming unit, the shift unit, the purification unit, and the product gas discharge unit. Wherein a condensed water discharge port is provided in at least one of the reforming section, the reforming section, the purification section, the generated gas discharge section, and the gas ventilation path.

At this time, it is effective to provide an on-off valve at the condensed water discharge port.

It is desirable that the opening / closing valve of the condensed water discharge port be opened for a certain period of time at the time of startup.

Further, it is effective to synchronize the start of the purge operation due to the injection of the inert gas and the opening operation of the on-off valve of the condensed water discharge port before starting.

Further, the present invention is a fuel cell system using a polymer electrolyte fuel cell that uses hydrogen gas generated by a hydrogen generator and an oxidizing gas as fuel, wherein the polymer electrolyte fuel cell is used. A water recovery unit for recovering water from discharged exhaust gas is provided, and discharged water discharged from a condensed water discharge port provided in the hydrogen generator is introduced into the water recovery unit. Thus, the water discharged from the fuel cell is collected without dripping to the outside. At this time, by providing the condensed water discharge port of the hydrogen generator above the water recovery unit, the flow of water is generated by gravity, and the water can be easily recovered to the water recovery unit.

[0014]

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a schematic configuration of the hydrogen generator of the present embodiment. Reference numeral 1 denotes a reforming section in which ruthenium is used as a reforming catalyst and which is loaded with alumina supported on alumina; 2 is a metamorphic section in which platinum is supported on CeO ₂ as a conversion catalyst; and 3 is a CO purification catalyst. As a mixture of platinum-ruthenium supported on alumina and filled with C
O purification unit. The carrier for supporting the catalyst can be appropriately selected from granules, pellets, honeycombs, and the like, and the material can be appropriately selected from ceramics, heat-resistant metals, and the like. Reference numeral 4 denotes a fuel supply unit, which uses a gaseous hydrocarbon fuel such as natural gas (city gas) or LPG or a liquid hydrocarbon fuel such as gasoline, kerosene, or methanol. Reference numeral 5 denotes a water supply section, 6 denotes a steam generation section, 7 denotes a steam supply section A to the reforming section, and 8 denotes a steam supply section B to the denaturation section. A heating unit 9 heats the catalyst of the reforming unit 1 and the steam generating unit 6. 10 is a purge gas supply unit using an inert gas,
Before starting, the combustible gas in the hydrogen generation path is purged.
Reference numeral 11 denotes a purifying air supply unit to the purifying unit 3, 12 a condensed water discharge port provided below the purifying unit, and 13 denotes a generated hydrogen rich gas outlet.

The operation at the time of startup will be described below. Heating unit 9
Thereby, the reforming section 1 and the steam generating section 6 are heated. After heating the reforming section 1 to a predetermined level, supply of fuel from the fuel supply section 4 to the reforming section 1 and supply of water from the water supply section 5 to the steam generation section 6 are started. Part of the steam generated by the steam generator 6 is supplied to the steam supply unit 7 and part of the steam is supplied to the steam supply unit 8. The steam supplied from the steam supply section 7 to the reforming section 1 and the fuel supplied from the fuel supply section 4 are mixed, reach the reforming catalyst section, and the reforming reaction is started. The reformed gas is mixed with the steam supplied from the steam supply unit 8 and reaches the denaturation unit for performing a denaturation reaction. The modified gas is mixed with the air supplied from the purification air supply unit 11, reaches the purification unit 3, is purified, becomes a hydrogen-rich gas, and is discharged from the generated hydrogen-rich gas outlet 13.

In the above configuration, for example, when the operation is stopped in a short time after the start of the operation, the temperatures of the reforming section and the purifying section are not sufficiently increased, so that the reformed gas and the moisture of the modified gas are condensed. As condensed water, for example, accumulates in the lower part of the purification unit. If the operation is restarted in this state, since heat is required to evaporate the accumulated condensed water, it takes a long time to raise the temperature of the purification catalyst to the activation temperature. In order to prevent this, in the present embodiment, a condensed water discharge port 12 is provided to discharge the condensed water.

(Embodiment 2) A second embodiment of the present invention will be described with reference to FIG.

FIG. 2 shows a schematic configuration of the hydrogen generator of the present embodiment. In the present embodiment, an opening / closing valve is provided at the condensed water discharge port 12 in addition to the first embodiment, so that the opening / closing operation can be easily performed.

(Embodiment 3) In a third embodiment of the present invention, in the second embodiment, the opening / closing valve is opened for a certain period of time at the start of operation and at the start of restart. The prescribed time is defined by measuring the time from the start of the opening operation or by defining the temperature based on temperature information at an appropriate position for judging the presence or absence of condensed water near the condensed water discharge port 12. There is. Accordingly, it is possible to prevent the on-off valve from being opened and the hydrogen-rich gas being generated being discharged even though the condensed water has disappeared.

(Embodiment 4) In a fourth embodiment of the present invention, in the second embodiment, before the start, the purge operation is started by injecting an inert gas and the opening / closing operation of the opening / closing valve of the condensed water outlet is performed. To synchronize. That is, the on-off valve is opened when the purge operation starts, and the on-off valve is closed when the purge operation ends. This ensures that before starting operation and restarting operation,
The condensed water in the passage can be pushed out and discharged to the condensed water discharge port at a high pressure by the purge operation.

(Embodiment 5) A fifth embodiment of the present invention will be described with reference to FIG. 14 is a polymer electrolyte fuel cell, 1
5 is an oxidizing gas supply unit, 16 is a condensed water recovery tank, 17
Is a condenser. The heating section 9 heats the reforming section 1 and the steam generating section 6. After heating the reforming unit 1 to a predetermined level,
The supply of fuel from the fuel supply unit 4 to the reforming unit 1 and the supply of water from the water supply unit 5 to the steam generation unit 6 are started. Part of the steam generated by the steam generator 6 is supplied to the steam supply unit 7 and part of the steam is supplied to the steam supply unit 8. The steam supplied from the steam supply unit 7 to the reforming unit 1 and the fuel supplied from the fuel supply unit 4 are mixed, reach the reforming catalyst unit, and undergo a reforming reaction. The reformed gas is mixed with the steam supplied from the steam supply unit 8, and reaches the shift unit for performing the shift reaction.

The metamorphic gas is mixed with the air supplied from the purified air supply unit 11, reaches the purification unit 3, is purified, becomes a hydrogen-rich gas, and is discharged from the generated hydrogen-rich gas outlet 13. Using the generated hydrogen-rich gas and the oxidizing gas supplied from the oxidizing gas supply unit 15, power generation is performed in the polymer electrolyte fuel cell 14, and the polymer electrolyte fuel cell 1
The gas discharged from 4 is condensed with water by a condenser 17 and collected by a condensed water collecting unit 16. In this configuration, the condensed water discharged from the condensed water discharge port 12 is introduced into the condensed water recovery tank 16. As a result, the discharged water can be collected without dripping to the outside. At this time, the condensed water discharge port 12 is configured to be higher than the condensed water recovery unit 16. Thereby, a flow of water is generated by gravity, and condensed water is easily collected.

[0024]

The effects of the present invention will be described below.

1. By providing a condensed water discharge port in at least one of the reforming section, the shift section, the purification section, the generated gas discharge section or the gas ventilation path, the operation is stopped in a short time after the start of the operation, and then restarted. Condensed water that accumulates in the passage at times or the like can be drained, and the time required to reach the catalyst activation temperature of the purification unit, that is, the startup time of the fuel cell can be reduced.

2. By providing an on-off valve at the condensed water discharge port, the on-off operation can be easily performed.

3. By defining the opening operation of the on-off valve as a fixed time at the start of operation and at the start of re-operation, even if condensed water is exhausted, the on-off valve is left open and the gas being generated is discharged. Can be prevented.

4. The operation of the on-off valve is synchronized with the purge operation in the generation path of the generated gas by the inert gas performed before the start of the operation and before the restart of the operation, so that the high pressure by the purge operation can be surely obtained before the start of the operation and the restart of the operation , The condensed water in the path can be pushed out to the condensed water discharge port and discharged.

5. By introducing the discharged water discharged from the condensed water discharge port into the condensed water collecting section recovered from the gas discharged from the polymer electrolyte fuel cell, the discharged water can be collected without dripping to the outside. At this time, by forming the condensed water discharge port on the upper side of the condensed water recovery section, the flow of water is generated by gravity, and the water can be easily collected in the condensed water recovery section.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a hydrogen generator according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a hydrogen generator according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a fuel cell system according to a fifth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reforming part 2 Metamorphic part 3 CO purification part 4 Fuel supply part 5 Water supply part 6 Steam generation part 7 Steam supply part A 8 Steam supply part B 9 Heating part 10 Purge gas supply part 11 Purified air supply part 12 Condensed water discharge port 13 Hydrogen-rich gas generation outlet 14 Polymer electrolyte fuel cell 15 Oxidant gas supply section 16 Condensed water recovery section 17 Condenser

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Chinori Aso 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Kunihiro Ukai 1006 Odaka Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co. (72) Inventor Akira Maenishi 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Kiyoshi Taguchi 1006 Odaka, Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. EA03 EA06 EA07 EB41 EB43 EB45 5H026 AA06 5H027 AA06 BA01 BA17 MM12

Claims (5)

[Claims] 1. A raw material supply unit, a water supply unit, an air supply unit, a reforming unit including a reforming catalyst for reacting the raw material with water, and a conversion unit for reacting carbon monoxide with water. A shift section provided with a catalyst, a purification section provided with a purification catalyst for oxidizing carbon monoxide, a product gas discharge section discharging the product gas passing through the purification section, the raw material supply section and the reforming section. A hydrogen gas generator that includes a gas passage that communicates with a gas generator, a gas converter, a purifier, and a generated gas discharge unit. A hydrogen generator, wherein a condensed water discharge port is provided in at least one of the section and the gas ventilation path. 2. The hydrogen generator according to claim 1, wherein an on-off valve is provided at the condensed water discharge port. 3. The method for operating a hydrogen generator according to claim 2, wherein the opening / closing valve of the condensed water discharge port is opened for a certain period of time upon startup. 4. The method for operating a hydrogen generator according to claim 2, wherein the purge operation start by injecting an inert gas and the opening operation of the on-off valve of the condensed water discharge port are synchronized before starting. . 5. A fuel cell system using a polymer electrolyte fuel cell using a hydrogen gas generated by the hydrogen generator according to claim 1 and an oxidant gas as fuel,
A water recovery unit for recovering water from exhaust gas discharged by the polymer electrolyte fuel cell is provided, and discharged water discharged from a condensed water discharge port provided in the hydrogen generator is introduced into the water recovery unit. And fuel cell system.