JP2001354401A - Starting method of hydrogen generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustible gas to be supplied to a hydrogen generator having a reforming section, a shift section, and a purifying section, wherein a generated gas delivered from the purifying section at startup is supplied to a burner. Is used as effectively as possible, and the start-up time of the hydrogen generator is shortened while preventing the reforming catalyst from deteriorating due to a high temperature at start-up and deterioration in characteristics due to low temperature. SOLUTION: After a flame is formed by a burner with a fuel and a generated gas sent from a hydrogen generator by supplying a raw material, a fuel supply amount is reduced and stopped, and thereafter, a raw material supply amount and an air supply amount are reduced. Increase. When the temperature of the reforming catalyst is higher than a predetermined value, the supply amount of air or water is increased, and when the temperature is lower than the predetermined value, the supply amount of air or water is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to natural gas, LP
The present invention relates to a method for starting a hydrogen generator that uses a hydrocarbon-based material such as G, gasoline, naphtha, kerosene, and methanol as a main raw material and generates a hydrogen-rich gas to be supplied to a hydrogen-using device such as a fuel cell.

[0002]

2. Description of the Related Art In recent years, hydrogen has been attracting attention as a promising alternative energy source for fossil fuels. However, there are various problems with its production cost, storage and transportation, and in particular, it is generally used for civil use. It has not been. In order to realize the use of hydrogen at an early stage, the most effective means is to use the existing industrial infrastructure (infrastructure) and generate the required amount of hydrogen at the required place. For example, city gas is used as a raw material for small and medium-sized on-site fuel cells, and methanol is used as a raw material for fuel cell vehicles, and a steam reforming method using catalytic reaction, a partial oxidation method, or a combination of both is used. It is conceivable to generate hydrogen by an autothermal method or the like. However, since the reforming reaction proceeds at a high temperature, carbon monoxide (hereinafter, referred to as “CO”) and carbon dioxide are generated as by-products other than hydrogen. When supplying the generated hydrogen to the fuel cell,
In particular, in a polymer electrolyte fuel cell, CO which is a by-product poisons the electrode of the fuel cell and significantly degrades its performance. Therefore, it is necessary to reduce the concentration of CO contained in hydrogen to about 20 ppm. On the other hand, in addition to the reforming section that performs the reforming reaction, the hydrogen generator includes a shift section that performs a shift reaction downstream of the reforming section, and finally a CO purification that reduces the CO concentration to about 20 ppm. Set up the department. By controlling the catalyst of each part to a temperature having good activity, C
The O concentration is realized, and high-purity hydrogen can be supplied to the fuel cell.

Specifically, in order to reduce the CO concentration in the hydrogen gas from the hydrogen generator to 20 ppm or less, the temperature must be set to a temperature at which the reforming section, the shift section, and the purifying section sufficiently function. This temperature varies depending on the type of catalyst used, etc., but is generally about 700 ° C. in the reforming section, about 300 ° C. in the shift section, and about 200 ° C. in the purifying section. In order to control the temperature to be optimal for the catalyst in this way, a heating source such as a burner is installed near the reforming section that needs to be heated to the highest temperature. Then, the raw material gas supplied to the reforming section is heated when passing through the reforming section and becomes high in temperature. Therefore, the temperature of the shift section and the purification section is raised using the raw material gas. However, since the reforming section, the shift section, and the purifying section are filled with the catalyst, the heat capacity is large, and it takes a considerable time to raise the temperature and stabilize the temperature. Therefore, immediately after the start of the hydrogen generator,
The amount of combustion in the burner forming a flame by the fuel supply is increased as much as possible, and the time for raising the temperature of the reforming section is shortened.

[0004]

Here, even if the amount of heating in the burner is increased, the shift section and the purification section are not directly heated, so that the time required for raising the temperature of the reforming section and stabilizing it is greatly increased. Could not be shortened. In addition, the reforming catalyst in the reforming section has a relatively narrow temperature range showing good reactivity and is in a high temperature range, so if it exceeds a predetermined temperature, it will be close to the heat resistance limit of the catalyst and may cause thermal degradation. There is. Therefore, in order to achieve the start-up in the shortest possible time while effectively using the raw material gas and the fuel gas, it is necessary to increase the amount of heat transferred to the burner while increasing the amount of heat transfer to the shift section and the purification section, as well as the shift section and the purification section. It was necessary to control the temperature of the reforming catalyst while maintaining the heat transfer to the section as constant as possible. Therefore, in order to solve such a problem, the present invention realizes a stable start-up in a short time by effectively using a start-up generated gas flowing out of the hydrogen generator at the start-up, and realizes hydrogen with excellent operability and convenience. It is an object of the present invention to provide a method for starting a generator.

[0005]

According to the present invention, there is provided a burner having a raw material supply unit, a water supply unit, a fuel supply unit and an air supply unit, and a raw material supply unit and a water supply unit located near the burner. (A) supplying a raw material from the raw material supply unit to the reforming unit at start-up, and sending out the raw material from the hydrogen generation device. Guiding at least a part of the generated gas to the burner, and forming a flame in the burner with the fuel from the fuel supply unit, the air from the air supply unit, and the generated gas; A step of reducing the amount of fuel supplied from the unit to the burner to stop the supply of fuel, and forming a flame with the air and the produced gas. In the step (b), it is effective to reduce the amount of fuel supplied from the fuel supply unit and the amount of air supplied from the air supply unit. Further, in the step (b), after the supply of fuel is stopped by decreasing the amount of fuel supplied from the fuel supply unit, the amount of raw material supplied from the raw material supply unit and the amount of air supplied from the air supply unit are reduced. It is effective to increase.

In the step (b), it is effective to decrease the amount of fuel supplied from the fuel supply unit and increase the amount of raw material supplied from the raw material supply unit. In the step (b), it is effective to increase the raw material supply amount by an amount corresponding to the reduced fuel supply amount. In the step (b), it is effective to keep the temperature of the reforming catalyst constant.
The temperature of the reforming catalyst can be kept constant by adjusting the amount of air supplied from the air supply unit or by adjusting the amount of water supplied from the water supply unit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for starting a hydrogen generator according to the present invention will be described with reference to FIG. FIG.
It is a schematic structure figure of one embodiment of a hydrogen generator used for performing a starting method of the present invention. A raw material supply section 1 and a water supply section 2 are connected to a reforming section 3 having a reforming catalyst filled therein. The raw material supplied by the raw material supply unit 1 flows out of the reforming unit 3, flows into the conversion unit 4 filled with the shift catalyst, and the gas flowing out of the shift unit 4 flows into the purification unit 5 filled with the CO removal catalyst. I do. That is, the hydrogen generator shown in FIG. 1 includes not only the reforming section, but also a shift section and a purification section. Then, the gas flowing out of the purification unit 5 passes through the three-way valve 6 as product gas, and one is guided from the hydrogen generator to the fuel cell 7 and the other is directed to the burner 8 installed near the reforming unit 3. The flow path is formed.

The burner 8 is provided with a fuel supply section 9 and an air supply section 10 for supplying combustion air. The combustion gas in the burner 8 is exhausted from an exhaust port 11 provided in the reforming section 3. Here, the raw material and the fuel supplied from the raw material supply unit 1 and the fuel supply unit 9 are gaseous hydrocarbon fuels such as natural gas (city gas) or LPG, or liquid hydrocarbons such as gasoline, kerosene or methanol. Fuel. However, when a liquid fuel is used, a fuel vaporization unit is required. In this case, it is preferable to form a vaporizing unit using the heat of conduction from the reforming unit 3 and the burner 8 and the sensible heat in the combustion exhaust gas.

Further, in order to adjust the supply amounts of the raw material from the raw material supply unit 1, the fuel from the fuel supply unit 9 and the air from the air supply unit 1, a control method using, for example, a pump or a fan is used. Or a method of controlling with a valve installed on the downstream side such as a pump or a fan. However, in FIG. 1, the supply amount (flow rate)
The regulators are not specifically shown, but each supply is shown as having a flow regulator. In addition,
The arrows in FIG. 1 indicate the direction of flow of the raw material, fuel, reaction gas, and the like. Further, a temperature detector 12 for measuring the temperature of the reforming catalyst filled therein is installed in the reforming section 3, and the amount of air supplied from the air supply section 10 and the temperature supplied from the water supply section 2 according to the detected temperature. The air supply amount can be controlled. Here, as the temperature detector 12, for example, a thermocouple or a high-temperature thermistor can be used.

<< Embodiment 1 >> Embodiment 1 of the starting method of the present invention will be described using the hydrogen generator shown in FIG. In order to supply the generated gas (start-up generated gas) sent from the purification unit 5 to the burner 8 at startup,
The flow path of the three-way valve 6 is on the burner side. This is because at the time of startup, the catalyst in the hydrogen generator is not sufficiently activated, so that the CO concentration of the produced gas to be delivered is not sufficiently reduced and cannot be used for a fuel cell or the like. This is because it is used as a part of gas. First,
In a state where combustion air is supplied from the air supply unit 10 to the burner 8, fuel is supplied from the fuel supply unit 9 to form a flame in the burner 8 while performing an ignition operation with an ignition device (not shown). After confirming the stable state of the flame, the raw material supply unit 1
By supplying the raw material to the reforming unit 3, the fuel supplied from the fuel supply unit 9 and the raw material supplied from the raw material supply unit 1 in the burner 8 are combined with the reforming unit 3, the shift unit 4, and the purification unit 5. And the generated starting gas that has passed burns.

After that, by reducing the amount of fuel supplied from the fuel supply unit 1 and stopping the operation, the flame in the burner 8 is maintained only by the generated gas at the time of starting, that is, only by the supply of the raw material from the raw material supply unit 1. Then, the amount of the raw material supplied from the raw material supply unit 1 is increased, and the air supply unit 1 is adjusted in accordance with the amount of the raw material supplied.
By increasing the temperature of each part by increasing the air supply amount from 0, the hydrogen generator is started. Here, the reforming section 3 is directly heated by the flame in the burner 8, but the shift section 4 and the purifying section 5 use the gas heated in the reforming section 3 to increase the temperature.
The temperature rises by passing through the shift section 4 and the purification section 5.

The fuel supplied from the fuel supply unit 9 contributes to the heating of the reforming unit 3 but does not directly participate in the heating of the shift unit 4 and the purification unit 5. Since the raw material from the raw material supply unit 1 passes through the shift unit 4 and the purification unit 5 and is supplied to the burner 8 as a start-up generated gas, the temperature of the shift unit 4 and the purification unit 5 increases, and the heating of the reforming unit 3 is performed. Directly involved in Therefore, at the time of startup, as the combustible gas for combustion in the burner 8, fuel is not supplied from the fuel supply unit 9,
It is more effective to supply the starting gas generated by supplying the raw material from the raw material supply unit 1. In a state where the generated gas is supplied to the burner 8 at the time of starting, the amount of the combustible gas in the burner 8 is increased by increasing the raw material supply amount, and the air corresponding to the gas amount is supplied. The amount of heating can be increased, and at the same time, the amount of heat medium to the shift section 4 and the purification section 5 can be increased. As a result, in a hydrogen generator that generates 30 liters / min of hydrogen,
When the starting is performed with the total amount of the source gas and the fuel gas used being the same, the starting time (CO is 20 pp.
m or less) can be reduced to about ２.

Here, from the beginning of the start-up, the raw material supply unit 1
It is sufficient that only the raw material is supplied to form a flame in the burner 8 so that the temperature can be raised. However, N ₂ by the N ₂ purge at the end of the previous operation and N ₂ mixed during the operation stop were introduced into the hydrogen generator. Air is present. Therefore, the raw material supply unit 1
It takes a long time before the raw material supplied to the burner 8 reaches the burner 8 and a flame can be formed by the ignition operation. That is, after the start-up, the time when the flame is formed in the burner 8 and the heating of the reforming section 3 is started is delayed. In particular, since the internal flow passages of the purification unit 3, the shift unit 4, and the purification unit 5 have a considerably large volume, the flammable gas supplied from the inlet of the reforming unit 3 is sent out from the purification unit 5 outlet. The time is not constant. Furthermore, the startup product gas coming sent, or have non flammable gas (N ₂ or air) is mixed, such as by the purge. Therefore, in order to reliably form a flame, the ignition operation must be performed for a considerably long time before the combustible gas is delivered until all the non-combustible gas mixed in the hydrogen generator is delivered. .

Usually, an igniter is used as an ignition device in consideration of heat resistance and mass productivity. However, during ignition operation, a high voltage is applied so that noise is given to a surrounding control system, which may hinder control. There is. Therefore,
The ignition operation needs to be completed in as short a time as possible. Therefore, as described above, in the start-up method of the hydrogen generator of the present invention, at the start of start-up, a flame is first formed with the fuel from the fuel supply unit 9, and then the raw material from the raw material supply unit 1 is supplied. After a flame is formed by the start-up generated gas containing a large amount of raw material and the fuel, the amount of fuel supplied from the fuel supply unit 9 is reduced and the fuel supply unit 9 is stopped. The fuel supply unit 9
If the amount of air supplied from the air supply unit 10 is reduced in accordance with the amount of decrease in the amount of fuel supplied when the fuel supply from the burner 8 is stopped, appropriate air for combustible gas in the burner 8 can be provided. Since the amount can be ensured, good combustion exhaust gas and a stable combustion state can be always realized.

Second Embodiment Next, a second embodiment of the present invention will be described. In the second embodiment, in the starting method according to the first embodiment using the hydrogen generator shown in FIG. 1, the amount of raw material supplied is increased when the fuel supply from the fuel supply unit 9 is reduced and stopped. According to this, since the amount of combustible gas in the burner 8 does not change much, it is easy to maintain a good combustion state without changing the amount of air supplied from the air supply unit 10. Further, it is possible to prevent a decrease in the heating amount due to the stop of the fuel supply. When the supply amount of the fuel at the time of starting is large and the supply amount of the raw material is small, if the supply of the fuel is stopped and only the supply of the raw material is performed, the heating amount in the burner 8 is reduced significantly even temporarily. Therefore, there is a possibility that the temperature rise of the reforming section 3 becomes gentle or sometimes the temperature falls. On the other hand, by increasing the supply amount of the raw material when stopping the fuel supply, if the heating amount in the reforming unit 3 is maintained, the temperature rise in the reforming unit 3 can be maintained.

At this time, if the amount of raw material equivalent to the reduced amount of fuel is increased from the raw material supply unit 1 and supplied, the good combustion state can be achieved without changing the air supply amount from the air supply unit 10 at all. Can be maintained. In particular, when the same hydrocarbon-based material such as methane is used as the raw material and the fuel, the combustion with the burner 8 generates the stoichiometric air amount for the fuel from the fuel supply unit 9 and the supply of the raw material from the raw material supply unit 1 to generate hydrogen. The theoretical gas amount of the product gas delivered from the apparatus and supplied to the burner 8 becomes substantially equal. Therefore, if the same amount is set as the increase in the raw material supply amount in accordance with the decrease amount of the fuel, the fuel supply can be performed without changing the combustion state without changing the supply air amount from the air supply unit 10 at all. Can be stopped.

Third Embodiment Next, a third embodiment of the present invention will be described. In the third embodiment, in the starting method according to the first embodiment using the hydrogen generator shown in FIG. 1, the fuel from the fuel supply unit 9 is stopped, and the flame from the burner 8 is caused by the raw material from the raw material supply unit 1. When the reforming section 3 is heated to increase and stabilize the temperature of each section, the temperature of the reforming catalyst is monitored by the temperature detector 12, and if the reforming catalyst temperature is higher than a predetermined value, air Supply unit 1
The air supply amount is increased from 0, and if the air supply amount is smaller than a predetermined value, the air supply amount is decreased, and control is performed so that the reforming catalyst has a predetermined value. There is an appropriate temperature range for the reforming catalyst to perform a good reaction, and the lower the temperature, the lower the rate at which the reaction proceeds. Conversely, if the temperature is too high, the reaction will proceed but the catalyst may cause thermal degradation. Therefore, it is necessary to optimize the temperature of the reforming catalyst by some means.

Here, if the amount of air supplied from the air supply unit 10 is increased, the amount of air in the burner 8 increases. However, when the amount of combustion is equal to the amount of air, the flame temperature increases as the amount of air increases. As the temperature decreases, the amount of heat in the combustion exhaust gas increases, and the amount of heat brought out from the exhaust port 11 increases. Therefore, the amount of heating of the reforming section 3 decreases, and the temperature of the reforming catalyst decreases.
Conversely, if the amount of air is reduced, the flame temperature can be increased, so that the amount of heat in the combustion exhaust gas can be reduced and the amount of heat released from the exhaust port 11 can be reduced. To increase the temperature of the reforming catalyst. However, such a phenomenon is caused by burner 8
This does not hold when the amount of air present in the flammable gas is less than the stoichiometric amount of flammable gas (the amount of flammable gas that can perform combustion reaction without excess or deficiency). This is a condition that is not practically used because CO is discharged or a large amount of soot is added to the exhaust gas passage.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, in the starting method according to the third embodiment using the hydrogen generator shown in FIG. 1, the temperature control of the reforming catalyst is performed by the air supply unit 10.
This is performed not with air from the water but with water supplied from the water supply unit 2. The temperature of the reforming catalyst is monitored by the temperature detector 12, and if the temperature of the reforming catalyst is higher than a predetermined value, the amount of water supplied from the water supply unit 2 is increased. The temperature of the reforming catalyst is controlled to a predetermined value. If the supply amount of water is increased, the amount of water existing inside the reforming section 3 increases, and more heat is taken to evaporate the water, so that the amount of heat contributing to the temperature rise of the reforming catalyst decreases. As a result, the temperature of the reforming catalyst decreases. If the amount of supplied water is reduced, the temperature of the reforming catalyst rises for the opposite reason, so that the temperature of the reforming catalyst can be controlled to an appropriate temperature by controlling the amount of supplied water.

As a method other than the above, it is conceivable to reduce the supply amount of the raw material from the raw material supply unit 1 when the temperature of the reforming catalyst is higher than a predetermined value, and to increase the supply amount when the temperature is lower. However, changing the raw material changes the amount of heating and also changes the flow rate of the heat medium to the shift unit 4 and the purification unit 5. In addition, since the heat capacity of each part is large, if the flow rate of the fluid flowing inside changes, the heat state inside is easily affected greatly, and it tends to take time until the state becomes stable. In the above method, the heat medium flow rate is hardly changed, and the amount of heat received and the amount of heat received by the heating unit in the water are changed. Is what you can do.

[0021]

As described above, according to the present invention, in the configuration in which the generated gas sent from the hydrogen generator is supplied to the burner at the time of start-up, after the flame is formed by the fuel and the raw material, the fuel is stopped and only the raw material is used. By maintaining the flame and then increasing the supply of raw materials and the supply of air, the temperature of the entire hydrogen generator is raised quickly while using the supplied gas as effectively as possible, thereby shortening the startup time. . Further, when the supply of fuel is stopped in a state where a flame is formed in the burner by the supply of fuel and raw material, a stable combustion state is ensured. Further, when a flame is formed in the burner by the combustible gas sent from the hydrogen generator by the raw material supply, and the temperature of the reforming unit and the temperature of the conversion unit and the purification unit are increased and stabilized, the reforming catalyst is used. It is intended to realize a short-time startup while keeping the temperature within an appropriate temperature range.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a hydrogen generator used to carry out a starting method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw material supply part 2 Water supply part 3 Reforming part 4 Transformation part 5 Purification part 6 Three-way valve 7 Fuel cell 8 Burner 9 Fuel supply part 10 Air supply part 11 Exhaust port 12 Temperature detection part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Masataka Ozeki 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Takeshi Tomizawa 1006 Kadoma Kadoma Kadoma City, Osaka Prefecture Matsushita Electric Industrial F Terms (reference) 4G040 EA02 EA03 EA06 EB03 EB12 EB22 EB43 5H027 BA01 BA16 BA17 KK42 MM12

Claims (5)

[Claims] 1. A burner having a raw material supply unit, a water supply unit, a fuel supply unit and an air supply unit, and a reformer located near the burner and connected to the raw material supply unit and the water supply unit. And a method for starting a hydrogen generator comprising:
(A) supplying a raw material from the raw material supply unit to the reforming unit at the time of starting, guiding at least a part of a product gas delivered from the hydrogen generator to the burner, and supplying the fuel from the fuel supply unit and the air Forming a flame in the burner with the air from the supply unit and the product gas; and (b) stopping the supply of fuel by reducing the amount of fuel supply from the fuel supply unit to the burner, A method for starting a hydrogen generator, comprising a step of forming a flame with the generated gas. 2. The hydrogen generator according to claim 1, wherein in the step (b), the amount of fuel supplied from the fuel supply unit is reduced, and the amount of air supplied from the air supply unit is reduced. How to start. 3. In the step (b), after the fuel supply from the fuel supply unit is reduced to stop the fuel supply,
3. The method according to claim 1, wherein the amount of raw material supplied from the raw material supply unit and the amount of air supplied from the air supply unit are increased. 4. 4. The hydrogen generator according to claim 1, wherein in the step (b), the amount of fuel supplied from the fuel supply unit is reduced and the amount of raw material supplied from the raw material supply unit is increased. How to start. 5. The method according to claim 1, wherein in step (b), the temperature of the reforming catalyst is kept constant.