JP2008254942A - Hydrogen production method and hydrogen production system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen production method by which the production of hydrogen can be carried out stably and efficiently. <P>SOLUTION: The hydrogen production method includes: a fuel reforming step of generating a hydrogen-containing reformed gas by an endothermic reaction from an elemental hydrogen-containing fuel; a step of generating heat for power generation and the endothermic reaction using the reformed gas and an oxidizing agent; a shift reaction step of converting carbon monoxide and steam in the reformed gas to hydrogen and carbon dioxide; a hydrogen separation step of separating hydrogen from a gas containing the hydrogen and the carbon dioxide by the shift reaction step; a hydrogen storage step of storing the hydrogen separated in the hydrogen separation step; a hydrogen storage quantity detection step of detecting the storage quantity of the hydrogen stored; and a step of monitoring a detected value by the hydrogen storage quantity detection step, wherein when the detected value decreases below a predetermined value, the supply quantity of the oxidizing agent is decreased and the supply quantity of the fuel is increased, and when the detected value of the hydrogen storage quantity detection means increases to the predetermined value, the supply quantity of the oxidizing agent is increased and the supply quantity of the fuel is decreased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrogen production method and a hydrogen production system for producing hydrogen from a fuel containing hydrogen element.

  A configuration of a conventional hydrogen production system will be described. FIG. 4 is a block diagram showing a configuration example of a conventional hydrogen production system. The hydrogen production system shown in FIG. 4 is a system for producing hydrogen from natural gas.

  As shown in FIG. 4, the hydrogen production system includes a desulfurizer 2, a steam generator 9, a reformer 3, a CO shift converter 4, a hydrogen separator 53, and a hydrogen reservoir 59. is there. The steam generator 9 is provided with a steam generator burner 10 and connected to a makeup water pump 7 for supplying makeup water 6. The reformer 3 is provided with a reformer starting burner 11 and a reformer burner 19. The hydrogen storage 59 is provided with a hydrogen storage amount detector 60, a control unit 65, and a hydrogen supply facility 63. The hydrogen supply facility 63 is connected to the hydrogen consuming means 64 through a hydrogen gas supply pipe.

  A pipe for supplying natural gas 1 to the hydrogen production system from the outside is branched into three. One of the three branch pipes is connected to the desulfurizer 2 via a shutoff valve 69 and a flow control valve 74. One of the other two is connected to the steam generator burner 10 via the shut-off valve 75 and the flow control valve 18. The remaining one is connected to the reformer starting burner 11 via the shut-off valve 13 and the flow control valve 15.

  The natural gas 34 whose flow rate is controlled by the flow rate control valve 74 is supplied to the desulfurizer 2. Natural gas 70 whose flow rate is controlled by the flow rate control valve 18 is supplied to the steam generator burner 10. The natural gas 32 whose flow rate is controlled by the flow rate control valve 15 is supplied to the reformer starting burner 11.

  Further, an air supply blower 12 for supplying air 14 necessary for combustion to various burners is provided, and an air supply pipe connected to the air supply blower 12 is branched into three. One of the three branch pipes is connected to the steam generator burner 10 via the shut-off valve 76 and the flow control valve 20. One of the other two is connected to the reformer starting burner 11 via the shutoff valve 17 and the flow control valve 78. The remaining one is connected to the reformer burner 19 via a shut-off valve 77 and a flow rate control valve 73.

  The air 72 whose flow rate is controlled by the flow rate control valve 73 is supplied to the reformer burner 19. The air 33 whose flow rate is controlled by the flow rate control valve 78 is supplied to the reformer starting burner 11. The air 71 whose flow rate is controlled by the flow rate control valve 20 is supplied to the steam generator burner 10.

  Each of the steam generator burner 10, the reformer starting burner 11, and the reformer burner 19 discharges exhaust gases 30, 29, and 31 due to combustion.

  A steam supply pipe extending from the steam generator 9 is connected to a gas pipe connected between the desulfurizer 2 and the reformer 3. A shutoff valve 8 and a flow control valve 28 are provided in the water vapor supply pipe. Steam 5 is mixed with the desulfurized natural gas 24 supplied from the desulfurizer 24, and the mixed gas 23 is introduced into the reformer 3.

  The reformer 3 and the CO shift converter 4 are connected by a gas pipe, and the reformed gas 22 supplied from the reformer 3 is introduced into the CO shift converter 4 through the gas pipe.

  The hydrogen separator 53 is connected to the CO shift converter 4 through a gas pipe, and is connected to the reformer burner 19 through a gas discharge pipe. The reformed gas 21 with the carbon monoxide concentration reduced to 1% or less is supplied from the CO shift converter 4 to the hydrogen separator 53 through the gas pipe. The exhaust gas 54 from the hydrogen separator 53 is supplied to the reformer burner 19 through the gas discharge pipe.

  The hydrogen separator 53 and the hydrogen storage 59 are connected by a gas pipe, and the hydrogen gas 58 supplied from the hydrogen separator 53 is introduced into the hydrogen storage 59 through the gas pipe.

  The control unit 65 is connected to each of the shutoff valves 69, 75, 13, 8, 77, 17, and 76 and the flow control valves 74, 18, 15, 28, 73, 78, and 20 via signal lines not shown in the figure. Connected to each. Further, the steam generator burner 10, the reformer starting burner 11, and the reformer burner 19 are connected to each other via signal lines not shown in the drawing. The control unit 65 is provided with a CPU (Central Processing Unit) (not shown) that executes predetermined processing according to a program, and a memory (not shown) for storing the program. The control unit 65 monitors the hydrogen storage amount detector 60 and transmits a control signal to the shutoff valve and the flow rate control valve according to the hydrogen storage amount. Further, an activation control signal, which is a signal for instructing activation, or a stop control signal for instructing combustion stop is transmitted to each burner according to the hydrogen storage amount. Further, it is connected to the reformer 3 via a signal line not shown in the figure, and the temperature of the reformer 3 is monitored.

  Note that a programmable logic controller (PLC) may be used instead of the CPU in the control unit 65.

  Next, a control method of the conventional hydrogen production system shown in FIG. 4 will be described.

  When the control unit 65 receives from the hydrogen storage amount detector 60 a detection signal indicating that the hydrogen storage amount of the hydrogen storage 59 has decreased to a predetermined value, the control unit 65 causes the shut-off valves 13 and 17 to open the valves. A control signal is transmitted, and an activation control signal is transmitted to the reformer activation burner 11. When the shutoff valves 13 and 17 are opened according to the control signal, the natural gas 32 and the air 33 are supplied to the reformer starting burner 11, and when the reformer starting burner 11 is started by the start control signal, the natural gas 32 is Start burning. The reformer 3 is heated by combustion of the reformer starting burner 11. The supply amounts of the natural gas 32 and the air 33 to the reformer starting burner 11 are controlled by the flow control valves 15 and 78 so as to have predetermined values set in advance.

  When the control unit 65 receives the detection signal from the hydrogen storage amount detector 60, the control unit 65 transmits a control signal for opening the valves to the shutoff valves 75 and 76, and sends an activation control signal to the steam generator 9. Send. When the shut-off valves 75 and 76 are opened according to the control signal, the natural gas 70 and the air 71 are supplied to the steam generator burner 10, and the steam generator 9 is started by the start control signal. Then, makeup water 6 is supplied from the makeup water pump 7 to the steam generator 9. In the steam generator 9, the steam 5 is generated from the makeup water 7 by the combustion of the natural gas 70.

  When the reformer 3 rises to a predetermined temperature, the control unit 65 transmits a control signal for opening the valve to the shutoff valve 69 and causes the shutoff valves 13 and 17 to close the valve. A control signal is transmitted, and a stop signal is transmitted to the reformer activation burner 11. When the shutoff valve 69 is opened according to the control signal, the natural gas 34 is supplied to the desulfurizer 2. When the shutoff valves 13 and 17 are closed according to the control signal, the supply of the natural gas 32 and the air 33 to the reformer starting burner 11 is stopped, and the reformer starting burner 11 is combusted according to the stop control signal. Stop.

  The supply amount of the natural gas 34 supplied to the desulfurizer 2 is controlled based on the relationship that the opening amount of the flow control valve 74 is increased as the value of the hydrogen storage amount detected by the hydrogen storage amount detector 60 is smaller. The part 65 is determined by setting the opening degree of the flow control valve 74 to a value corresponding to the hydrogen storage amount. As the opening degree of the flow control valve 74 is increased, the supply amount of the natural gas 34 is increased.

  In the desulfurizer 2, the sulfur content in the natural gas 1 is adsorbed and the sulfur content is removed from the natural gas 1. The sulfur content is contained in a odorant such as mercaptan in the natural gas 1 and causes deterioration of the reforming catalyst of the reformer 3. The desulfurized natural gas 24 desulfurized by the desulfurizer 2 is mixed with the water vapor 5 and then supplied to the reformer 3 as a mixed gas 23 of water vapor and desulfurized natural gas.

  The supply amount of the water vapor 5 mixed with the desulfurized natural gas 24 is a relationship between the supply amount of the natural gas 34 and the supply amount of the water vapor 5 so as to have a predetermined steam carbon ratio in accordance with the reaction of the formula (1) described later. That is, the relationship between the opening degree of the flow rate control valve 74 and the opening degree of the flow rate control valve 28 is obtained in advance, and the controller 65 sets the opening degree of the flow rate control valve 28 based on the relationship, thereby supplying the natural gas 34. The predetermined steam carbon ratio is determined according to the amount.

  In addition, the control unit 65 transmits a control signal for opening the valve to the shut-off valve 77 and transmits an activation control signal to the reformer burner 19. When the shut-off valve 77 is opened according to the control signal, the air 72 is supplied to the reformer burner 19. Exhaust gas 54 is supplied from the hydrogen separator 53 to the reformer burner 19. The reformer burner 19 starts combustion of the exhaust gas 54 and the air 72 by the activation control signal.

  The supply amount of the air 72 of the reformer burner 19 is a relationship between the supply amount of the natural gas 34 and the supply amount of the air 72 so that a predetermined air-fuel ratio is obtained, that is, the opening degree of the flow control valve 74 and the flow control valve 73. Based on the relationship between the opening degrees, the control unit 65 sets the opening degree of the flow rate control valve 73 so that the air / fuel ratio is determined to correspond to the supply amount of the natural gas 34.

  In the reformer 3, a steam reforming reaction of hydrocarbons contained in the natural gas 1 is performed by the action of a reforming catalyst such as a filled nickel catalyst or ruthenium catalyst, and carbon monoxide and hydrogen as main components. The reformed gas 22 containing is produced | generated. Here, the steam reforming reaction of methane, which is the main component of the natural gas 1, is expressed by the following equation (1).

(Methane steam reforming reaction)
CH ₄ + H ₂ O → CO + 3H ₂ (1)
The steam reforming reaction of hydrocarbon such as the steam reforming reaction of methane shown in the equation (1) is an endothermic reaction, and a reaction necessary from the outside of the reformer 3 to efficiently generate hydrogen. It is necessary to supply heat and maintain the temperature of the reformer 3 at 700 to 750 ° C. For this reason, the reaction gas necessary for the steam reforming reaction is supplied to the reformer 3 by burning the exhaust gas 54 and the air 72 in the reformer burner 19. The reformed gas 22 containing carbon monoxide, hydrogen, unreacted steam, methane, carbon dioxide and the like generated in the reformer 3 is supplied to the CO shift converter 4 filled with a shift catalyst such as a copper-zinc catalyst. Supplied.

  In the CO shift converter 4, the carbon monoxide concentration of the reformed gas 22 is reduced to 1% or less by performing an aqueous shift reaction represented by the following equation (2), which is an exothermic reaction, by the action of the shift catalyst.

(Water-based shift reaction)
CO + H ₂ O → CO ₂ + H ₂ (2)
The reformed gas 21 generated by the CO shift converter 4 and having the carbon monoxide concentration reduced to 1% or less is supplied to the hydrogen separator 53.

  The hydrogen separator 53 separates hydrogen (high purity hydrogen) 58 in the reformed gas 21. The hydrogen separator 53 may be one that separates the hydrogen 58 in the reformed gas 21 using a hydrogen separation membrane such as a palladium membrane, and the reformed gas using PSA (Pressure Swing Adsorption). The hydrogen 58 may be separated by removing the impurities in 21 and purifying. When separating the hydrogen 58 in the reformed gas 21 by the hydrogen separator 53, the reformed gas 21 is boosted using a boosting means (not shown) as necessary in order to perform efficient hydrogen separation. .

  The hydrogen 58 separated by the hydrogen separator 53 is supplied to the hydrogen reservoir 59 and stored therein. The hydrogen storage 59 may be a hydrogen storage unit using a hydrogen storage alloy having a storage pressure of less than 1 MPa, or may be a high-pressure storage unit having a storage pressure of about 40 MPa. In storing the hydrogen 58 in the hydrogen storage 59, the pressure of the hydrogen 58 is increased using a pressure increasing means (not shown) as necessary. The amount of hydrogen 58 stored in the hydrogen storage 59 is monitored by the hydrogen storage detector 60 detecting it. The hydrogen storage amount detector 60 may be, for example, a weight detection unit that detects the weight of the stored hydrogen 58, or may be a pressure detection unit that detects the pressure of the stored hydrogen 58.

  The hydrogen 58 stored in the hydrogen reservoir 59 is a hydrogen supply facility 63 such as a dispenser (when the hydrogen 58 is stored at a low pressure) or a high-pressure dispenser (when hydrogen is stored at a high pressure) as hydrogen supply means, if necessary. To the hydrogen consuming means 64 such as a fuel cell vehicle and a stationary fuel cell.

  On the other hand, the exhaust gas 54 after the hydrogen 58 is separated from the reformed gas 21 by the hydrogen separator 53 is discharged from the hydrogen separator 53. Since the exhaust gas 54 contains hydrogen that has not been separated by the hydrogen separator 53, the exhaust gas 54 is supplied to the reformer burner 19 to burn the exhaust gas 54 with the air 72 as described above. Thus, reaction heat necessary for the steam reforming reaction of natural gas in the reformer 3 is supplied to the reformer 3.

An example of a hydrogen production system is disclosed in Non-Patent Document 1.
Tetsuya Mori, Efforts for Hydrogen Utilization Society: Osaka Gas, Clean Energy, May 2003, pp. 22-26 (2003)

  Problems of the hydrogen production method by the conventional hydrogen production system shown in FIG. 4 will be described. In order to clarify the problem, the procedure for producing hydrogen will be described below again.

  In the conventional control method of the hydrogen production system, when the hydrogen storage amount detector 60 detects that the hydrogen storage amount of the hydrogen storage 59 has decreased to a predetermined value, the reformer start burner 11 is supplied with natural gas. The reformer 3 is heated by supplying and burning 32 and air 33, and the steam 5 is generated by the steam generator 9 by supplying and burning the natural gas 70 and air 71 to the steam generator burner 10. .

  When the reformer 3 reaches a predetermined temperature, the supply of the natural gas 32 and the air 33 to the reformer starting burner 11 is stopped, the combustion of the reformer starting burner 11 is stopped, and the desulfurizer 2 is stopped. Of the natural gas 34 is started, and hydrogen and carbon monoxide are generated by the steam reforming reaction of the natural gas 1 in the reformer 3. Hydrogen and carbon dioxide are generated by supplying the reformed gas 22 containing hydrogen and carbon monoxide generated in the reformer 3 to the CO shift converter 4 and reacting carbon monoxide and steam in the reformed gas 22 with each other. Let

  The reformed gas 21 having the carbon monoxide concentration reduced to 1% or less by the CO shift converter 4 is supplied to the hydrogen separator 53 to separate the hydrogen 58. The hydrogen 58 separated by the hydrogen separator 53 is stored in the hydrogen reservoir 59. The exhaust gas 54 containing hydrogen, methane and the like is supplied to the reformer burner 19 and burned with air 72 in the reformer burner 19 to reform the reaction heat necessary for the steam reforming reaction of the natural gas 1. Used to supply the vessel 3.

  On the other hand, when the hydrogen storage amount detector 60 detects that the hydrogen storage amount of the hydrogen storage device 59 has increased to a predetermined value, the supply of the natural gas 34 to the desulfurizer 2 is stopped and the water vapor generator The supply of the natural gas 70 and the air 71 to the burner 10 is stopped, the production of hydrogen in the reformer 3 and the generation of water vapor in the water vapor generator 9 are stopped, and the storage of the hydrogen 58 in the hydrogen storage 59 is finished.

  In the conventional control method of the hydrogen production system, it is necessary to perform steam generation in the steam generator 9 and hydrogen production in the reformer 3 in accordance with the hydrogen storage amount of the hydrogen storage 59. When the amount of hydrogen used per unit time is small, steam generation and stoppage in the steam generator 9 and hydrogen production and stoppage in the reformer 3 are frequently repeated in a short time. In this case, every time the stopped hydrogen production system is started, a large amount of energy is expended for increasing the temperature of the steam generator 9 and the reformer 3. Thus, when the operation rate of the hydrogen production system is low, there is a problem that energy for heat generation is consumed every time the system is started, and the energy consumption is large.

  The present invention has been made to solve the above-described problems of the prior art, and provides a hydrogen production method and a hydrogen production system capable of stably and efficiently producing hydrogen. For the purpose.

To achieve the above object, the hydrogen production method of the present invention comprises:
A fuel reforming step of generating a reformed gas containing hydrogen from a fuel containing elemental hydrogen by an endothermic reaction;
Generating heat for power generation and endothermic reaction using the reformed gas and oxidant;
A shift reaction step of converting carbon monoxide and water vapor in the reformed gas into hydrogen and carbon dioxide;
A hydrogen separation step of separating hydrogen from a gas containing hydrogen and carbon dioxide by a shift reaction step;
A hydrogen storage step for storing hydrogen separated in the hydrogen separation step;
A hydrogen storage amount detection step for detecting the amount of stored hydrogen; and
When the detection value by the hydrogen storage amount detection step is monitored and the detection value decreases below a predetermined value, the supply amount of fuel is increased while decreasing the supply amount of oxidant, and the detection value of the hydrogen storage amount detection means is When increasing to a predetermined value, increasing the supply of oxidant and decreasing the supply of fuel;
It is what has.

  In the present invention, when the amount of stored hydrogen decreases below a predetermined value, the amount of oxidant supplied is reduced and the amount of fuel supplied is increased to generate hydrogen necessary for power generation of the fuel cell. It is possible to generate the hydrogen required for storage at the same time while generating power from the fuel cell at the specified temperature and output, and when the hydrogen storage amount reaches the specified value, the supply amount of oxidant By increasing the amount of fuel and decreasing the amount of fuel supplied, the hydrogen required for power generation by the fuel cell is generated and the power generation by the fuel cell is continued at the specified temperature and output, while the generation of the hydrogen required for storage is stopped simultaneously. Is possible. In the present invention, it is not necessary to provide a burner for generating heat necessary for the reaction in the fuel reforming process.

Moreover, the hydrogen production system of the present invention for achieving the above object is
A fuel reforming means for generating a reformed gas containing hydrogen from the fuel by an endothermic reaction when a fuel containing hydrogen element is supplied;
A fuel cell that generates heat for power generation and endothermic reaction using a reformed gas and an oxidant; and
When the reformed gas is supplied, a shift reaction means for converting carbon monoxide and water vapor in the reformed gas into hydrogen and carbon dioxide,
A hydrogen separation means for separating hydrogen from an exhaust gas containing hydrogen and carbon dioxide by a shift reaction means;
Hydrogen storage means for storing hydrogen separated by the hydrogen separation means;
A hydrogen storage amount detection means for detecting a storage amount of hydrogen stored in the hydrogen storage means;
When the detection value by the hydrogen storage amount detection means is monitored and the detection value decreases below a predetermined value, the supply amount of fuel is increased while decreasing the supply amount of the oxidant, and the detection value increases to the predetermined value. A controller that increases the amount of oxidant supplied and decreases the amount of fuel supplied;
It is the structure which has.

  According to the present invention, when it is not necessary to store hydrogen, only hydrogen used for power generation of the fuel cell is generated, and hydrogen necessary for storage is not generated. There is no need to repeatedly start and stop the production system, and the hydrogen production system can be operated stably and efficiently.

  The hydrogen production system of the present invention generates hydrogen to be stored and hydrogen to be used for power generation, and is provided with a fuel cell that continuously generates power at a predetermined temperature and output, according to the remaining amount of hydrogen stored, The oxidant supply amount and the fuel supply amount are changed, and the generation of hydrogen to be stored is controlled while power generation by the fuel cell is continued at a predetermined temperature and output. Examples of the present invention will be described below.

  The hydrogen production system of the present embodiment performs hydrogen production and generates power using a solid oxide fuel cell.

  The configuration of the hydrogen production system of this example will be described. FIG. 1 is a block diagram illustrating a configuration example of the hydrogen production system according to the present embodiment. In addition, about the structure similar to the past, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  As shown in FIG. 1, the hydrogen production system of the present embodiment corresponds to a desulfurizer 2, a reformer 3 corresponding to a fuel reforming unit, a CO shift converter 4 corresponding to a shift reaction unit, and a fuel cell. The solid oxide fuel cell 38, the air preheater 61, the hydrogen separator 53 corresponding to the hydrogen separation means, and the hydrogen storage 59 corresponding to the hydrogen storage means.

  The solid oxide fuel cell 38 has a fuel electrode 35, a solid oxide electrolyte 36 and an oxidant electrode 37. An output adjusting device 48 for adjusting the output to the load 49 is connected to the solid oxide fuel cell 38.

  The air preheater 61 is provided with an air preheater burner 62. Further, the air supply blower 12 and the air supply pipe are connected. The air supply pipe is provided with a flow rate control valve 43 for controlling the flow rate of the air supplied to the air preheater 61.

  The hydrogen storage device 59 is provided with a hydrogen storage amount detector 60 corresponding to a hydrogen storage amount detection means, a control unit 70, and a hydrogen supply facility 63. The hydrogen supply facility 63 is connected to the hydrogen consuming means 64 through a hydrogen gas supply pipe.

  Next, connection of piping provided between apparatuses will be described.

  A gas supply pipe provided with a flow rate control valve 27 is connected to the desulfurizer 2, and the natural gas 1 is supplied to the desulfurizer 2 from the outside through the gas supply pipe. The desulfurizer 2 is connected to the reformer 3 by gas piping.

  The reformer 3 and the CO shift converter 4 are connected by a reformed gas supply pipe, and a shutoff valve 79 and a flow control valve 47 are provided in the reformed gas supply pipe. The reformed gas 22 supplied from the reformer 3 is introduced into the CO shift converter 4 through the gas supply pipe. In the reformed gas supply pipe, the pipe is branched between the reformer 3 and the shutoff valve 79, and the branched pipe is connected to the fuel electrode 35. Thereby, the reformed gas 22 from the reformer 3 is supplied to the fuel electrode 35.

  The CO shift converter 4 and the hydrogen separator 53 are connected by a gas pipe, and the reformed gas 21 whose carbon monoxide concentration is reduced to 1% or less is transferred from the CO shift converter 4 to the hydrogen separator 53 through the gas pipe. Supplied. The hydrogen separator 53 and the hydrogen storage 59 are connected by a gas pipe, and the hydrogen 58 supplied from the hydrogen separator 53 is introduced into the hydrogen storage 59 through the gas pipe.

  The fuel electrode 35 and the air preheater burner 62 are connected by a gas discharge pipe for supplying the exhaust gas 42 of the fuel electrode 35 to the air preheater burner 62. Further, the gas discharge pipe is branched in the middle, and the branched pipe is connected to the gas pipe connecting the desulfurizer 2 and the reformer 3 via the flow rate control valve 40. The desulfurized natural gas 24 supplied from the desulfurizer 2 and the exhaust gas 41 supplied from the fuel electrode 35 are mixed, and the mixed gas 23 is introduced into the reformer 3.

  The hydrogen separator 53 and the air preheater burner 62 are connected by a gas discharge pipe for supplying the exhaust gas 54 of the hydrogen separator 53 to the air preheater burner 62. The oxidant electrode 37 and the air preheater burner 62 are connected by a gas discharge pipe for supplying the exhaust gas 44 of the oxidant electrode 37 to the air preheater burner 62. The air preheater 61 and the oxidant electrode 37 are connected by an air supply pipe for supplying air 39 serving as an oxidant to the oxidant electrode 37.

  Next, the solid oxide fuel cell 38 will be described in detail. For the sake of explanation, FIG. 1 shows that the solid electrolyte fuel cell 38 is constituted by a set of single cells each including a fuel electrode 35, a solid oxide electrolyte 36, and an oxidant electrode 37. The solid oxide fuel cell 38 has a stack structure in which a plurality of the single cells are stacked.

A metal oxide electrode catalyst is used for the oxidant electrode 37. In the oxidant electrode 37, oxygen in the air 39 supplied from the air preheater 61 reacts with electrons by the oxidant electrode reaction shown in the following formula (3) by the action of the metal oxide electrode catalyst and is oxidized. It changes to a product ion (O ²⁻ ).

(Oxidant electrode reaction)
(1/2) O ₂ + 2e ⁻ → O ²⁻ (3)
The oxide ions generated at the oxidant electrode 37 move inside the solid oxide electrolyte 36 such as stabilized zirconia (YSZ) and reach the fuel electrode 35. In the fuel electrode 35, oxide ions are supplied to the fuel electrode 35 by the reaction shown in the following equations (4) and (5) by the action of a metal electrode catalyst such as nickel-YSZ cermet, ruthenium-YSZ cermet, etc. It reacts with hydrogen and carbon monoxide in the hydrogen-rich reformed gas 22 to be generated, and steam or carbon dioxide and electrons are generated.

(Fuel electrode reaction)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (4)
CO + O ²⁻ → CO ₂ + 2e ⁻ (5)
Electrons generated at the fuel electrode 35 move through an external circuit (not shown) and reach the oxidant electrode 37. The electrons that have reached the oxidant electrode 37 react with oxygen by the oxidant electrode reaction shown in the equation (3). In the process that the electrons move through the external circuit, electric power can be taken out as the fuel cell DC output 50.

  The fuel cell direct current output 50 obtained by the power generation of the solid oxide fuel cell 38 is subjected to voltage conversion and direct current to alternating current conversion by the output adjusting device 48 in accordance with the load 49, and then the transmission end alternating current output 51. To the load 49. In the present embodiment, the output adjustment device 48 performs conversion from direct current to alternating current. However, the output adjustment device 48 may perform only voltage conversion and supply the power transmission end direct current output to the load 49.

  The power generation temperature of the solid oxide fuel cell 38 is generally 800 to 1000 ° C., and the temperature in the range is maintained by heat generation due to the cell reaction. For this reason, the high-temperature exhaust heat of the solid oxide fuel cell 38 is used as the reaction heat of the hydrocarbon steam reforming reaction in the reformer 3. Thereby, the temperature of the reformer 3 can be maintained at 700 to 750 ° C.

  Summarizing equations (3) and (4), and summing equations (3) and (5), the cell reaction of the solid oxide fuel cell 38 is shown in the following equation (6) from “hydrogen and oxygen”. It is expressed as “reverse reaction of electrolysis of water to produce water vapor” and “reaction for generating carbon dioxide from carbon monoxide and oxygen” shown in the following formula (7).

(Battery reaction)
H ₂ + (1/2) O ₂ → H ₂ O (6)
CO + (1/2) O ₂ → CO ₂ (7)
As described above, a part of the exhaust gas 42 containing the steam generated by the cell reaction at the fuel electrode 35 is discharged to supply the steam necessary for the steam reforming reaction of hydrocarbons in the reformer 3. The gas 41 is mixed with the desulfurized natural gas 24, and the mixed gas 23 is supplied to the reformer 3. Since the remainder of the exhaust gas 42 contains unreacted hydrogen and unreacted carbon monoxide, it is supplied to the air preheater burner 62 together with the exhaust gas 44 from the oxidant electrode 37 as the exhaust gas 45.

  Next, the air preheater burner 62 will be described.

  The air preheater burner 62 burns the exhaust gases 45 and 44 from the solid oxide fuel cell 38 and the exhaust gas 54 from the hydrogen separator 53 to generate heat. The generated heat is used for preheating air 39 to be supplied to the oxidant electrode 37 by exchanging heat with the air 14 supplied from the air supply blower 12 to the air preheater 61. The exhaust gas 80 resulting from the combustion in the air preheater burner 62 can be used for hot water supply, heating, a heat source for cooling by an absorption refrigerator, and the like.

  Next, the control unit 70 will be described.

  The control unit 70 is connected to each of the shutoff valve 79 and the flow rate control valves 27, 40, 47, and 43 via signal lines not shown in the drawing. Further, it is connected to the air preheater burner 62 through a signal line not shown. The control unit 70 is provided with a CPU (not shown) that executes predetermined processing according to a program and a memory (not shown) for storing the program. Note that a PLC may be used instead of the CPU.

  The control unit 70 monitors the detection value of the hydrogen storage amount detector 60. When the detection value decreases below a predetermined value, the control unit 70 decreases the oxidant supply amount and increases the fuel supply amount. Further, when the detection value of the hydrogen storage amount detector 60 increases to a predetermined value, the supply amount of the oxidant is increased and the supply amount of the fuel is decreased. The supply amount of the oxidant is controlled by the opening degree of the flow control valve 43. Increasing the opening degree of the flow control valve 43 increases the supply amount of the oxidant, and decreasing the opening degree decreases the supply amount of the oxidant. The fuel supply amount is controlled by the opening degree of the flow control valve 27. Increasing the opening degree of the flow control valve 27 increases the amount of fuel supplied, and decreasing the opening degree decreases the amount of fuel supplied. Furthermore, the opening degree of the flow control valves 40 and 47 is controlled corresponding to the hydrogen storage amount.

  Since the desulfurizer 2, the reformer 3, the CO shift converter 4, the hydrogen separator 53, and the hydrogen storage 59 have the same configuration as the conventional one, detailed description thereof will be omitted.

  Next, a control method for the hydrogen production system of this embodiment will be described.

  The hydrogen storage amount detector 60 detects the storage amount of the hydrogen 58 stored in the hydrogen storage 59, and monitors whether the detected value becomes smaller than a predetermined value. Hydrogen 58 stored in the hydrogen reservoir 59 is supplied to a hydrogen consuming means 64 such as a fuel cell vehicle and a stationary fuel cell via a hydrogen supply facility 63 such as a dispenser or a high pressure dispenser corresponding to the hydrogen supply means. To be supplied.

  When the storage amount decreases due to the consumption of hydrogen and the detection value of the hydrogen storage amount detector 60 becomes smaller than a predetermined value, the control unit 70 adjusts the opening degree of the flow control valve 27. In other words, the supply amount of the natural gas 1 is determined based on the relationship between the battery current of the fuel cell DC output 50 and the storage amount of hydrogen and the opening degree of the flow control valve 27. It is determined by setting it to a value commensurate with the current and the amount of hydrogen stored. Here, when the hydrogen storage amount decreases due to the consumption of hydrogen and the detection value of the hydrogen storage amount detector 60 becomes smaller than a predetermined value, the control unit 70 sets the opening degree of the flow control valve 27 to the battery current and the hydrogen storage amount. By setting to a value commensurate with the above, the opening degree of the flow control valve 27 is increased, and the supply amount of the natural gas 1 supplied to the desulfurizer 2 is increased. At that time, the control unit 70 may decrease the opening degree of the flow control valve 27 in inverse proportion to the hydrogen storage amount, or the control unit 70 may increase the opening degree of the flow control valve 27 by a predetermined ratio. Good. Further, when the hydrogen storage amount increases and the detection value of the hydrogen storage amount detector 60 increases to a predetermined value, the control unit 70 sets the opening of the flow control valve 27 to a value commensurate with the battery current, The opening degree of the flow control valve 27 is reduced, and the supply amount of the natural gas 1 supplied to the desulfurizer 2 is reduced.

  Further, the control unit 70 increases the supply amount of the natural gas 1 supplied to the desulfurizer 2 when the hydrogen storage amount decreases due to the consumption of hydrogen and the detection value of the hydrogen storage amount detector 60 becomes smaller than a predetermined value. In order to generate hydrogen necessary for storage, the opening degree of the flow control valves 40, 47, 43 is adjusted. Details of the control of each flow control valve will be described in each operation part.

  The desulfurizer 2 adsorbs the sulfur content in the supplied natural gas 1 and removes the sulfur content from the natural gas 1. The sulfur content is contained in a odorant such as mercaptan in the natural gas 1 and causes deterioration of the reforming catalyst of the reformer 3 and the electrode catalyst at the fuel electrode 35 of the solid oxide fuel cell 38.

  The desulfurized natural gas 24 desulfurized in the desulfurizer 2 is mixed with the exhaust gas 41 containing water vapor generated by the cell reaction in the solid oxide fuel cell 38, and the mixed gas 23 of the water vapor and desulfurized natural gas 24 is reformed. Is supplied to the vessel 3. The supply amount of the exhaust gas 41 is the relationship between the supply amount of the natural gas 1 and the supply amount of the exhaust gas 41 so that the predetermined steam carbon ratio conforms to the reaction of the equation (1), that is, the opening degree of the flow control valve 27. And the opening degree of the flow rate control valve 40 are obtained in advance, and the control unit 70 sets the opening degree of the flow rate control valve 40 based on the relationship, whereby predetermined steam corresponding to the supply amount of the natural gas 1 is set. The carbon ratio is determined.

  The reformer 3 is maintained at 700 to 750 ° C. by high-temperature exhaust heat from the solid oxide fuel cell 38 and is included in the natural gas 1 by the action of a reforming catalyst such as a filled nickel catalyst or ruthenium catalyst. Hydrocarbon steam reforming reaction is performed to produce reformed gas 22 containing carbon monoxide and hydrogen as main components. This is because the steam reforming reaction of hydrocarbons such as the steam reforming reaction of methane shown in the formula (1) is an endothermic reaction, and the temperature of the reformer 3 is maintained at 700 to 750 ° C. efficiently. This is because hydrogen is generated.

  When the hydrogen storage amount decreases due to the consumption of hydrogen and the detection value of the hydrogen storage amount detector 60 becomes smaller than a predetermined value, the control unit 70 opens the shut-off valve 79 and the reformed gas generated in the reformer 3 A part is supplied as the reformed gas 25 to the fuel electrode 35 of the solid oxide fuel cell 38, and the rest is supplied to the CO shift converter 4. The supply amount of the reformed gas 26 to the CO shift converter 4 is based on the relationship between the hydrogen storage amount and the opening degree of the flow control valve 47, and the control unit 70 changes the opening degree of the flow control valve 47 to the hydrogen storage amount. It is determined by setting it to an appropriate value. At that time, the control unit 70 may decrease the opening degree of the flow control valve 27 in inverse proportion to the hydrogen storage amount, or the control unit 70 may set the opening degree of the flow control valve 27 to a predetermined value. Good. As the opening degree of the flow control valve 47 is larger, the supply amount of the reformed gas 26 is increased. When the hydrogen storage amount increases and the detection value of the hydrogen storage amount detector 60 increases to a predetermined value, the control unit 70 closes the shut-off valve 79 and the reformed gas generated in the reformer 3 is reformed gas. 25 are all supplied to the fuel electrode 35 of the solid oxide fuel cell 38.

  Here, the operation of the solid oxide fuel cell 38 will be described.

  A part of the air 14 taken in using the air supply blower 12 is supplied as the air 39 to the oxidant electrode 37 of the solid oxide fuel cell 38. The supply amount of the air 39 increases the supply amount of the air 39 as the direct current of the fuel cell DC output 50 of the solid oxide fuel cell 38 increases, and the supply amount of the reformed gas 26 to the CO shift converter 4 increases. Based on the relationship of reducing the supply amount of the air 39, in other words, based on the direct current of the fuel cell DC output 50 and the relationship between the opening degree of the flow rate control valve 47 and the opening degree of the flow rate control valve 43, the control unit 70 determines the flow rate. It is determined by setting the opening degree of the control valve 43 to a value commensurate with the DC current of the fuel cell DC output 50 and the supply amount of the reformed gas 26. If the direct current of the fuel cell DC output 50 is constant, the controller 70 changes the opening of the flow control valve 43 based on the relationship between the opening of the flow control valve 47 and the opening of the flow control valve 43. The supply amount of the air 39 is determined by setting the value corresponding to the supply amount of the quality gas 26.

In the solid oxide fuel cell 38, as described above, the oxygen in the air 39 reacts with the electrons by the reaction shown in the equation (3) by the action of the metal oxide electrode catalyst, and oxide ions (O ^{2 -} changes to). The oxide ions move inside the solid oxide electrolyte 36 and reach the fuel electrode 35. In the fuel electrode 35, the oxide ions react with hydrogen and carbon monoxide by the reaction shown in the equations (4) and (5) by the action of the metal-based electrode catalyst, and water vapor or carbon dioxide and electrons are generated. .

  Electrons generated at the fuel electrode 35 travel through an external circuit and reach the oxidant electrode 37. The electrons that have reached the oxidant electrode 37 react with oxygen by the oxidant electrode reaction shown in the equation (3). In the process of moving the electrons through the external circuit, power is taken out as the fuel cell DC output 50. The fuel cell DC output 50 is supplied to the load 49 as a power transmission end AC output 51 after voltage conversion and DC to AC conversion are performed by the output adjustment device 48 in accordance with the load 49.

  The power generation temperature of the solid oxide fuel cell 38 is generally 800 to 1000 ° C., and the power generation temperature is maintained by the heat generated by the cell reaction. Therefore, the high-temperature exhaust heat of the solid oxide fuel cell 38 can be used as the reaction heat of the hydrocarbon steam reforming reaction in the reformer 3 as described above.

  Water vapor is generated by the reaction of the expression (6) that summarizes the expressions (3) and (4), and carbon dioxide is generated by the reaction of the expression (7) that combines the expressions (3) and (5). A part of the generated exhaust gas 42 containing water vapor is mixed with the desulfurized natural gas 24 as the exhaust gas 41, and the mixed gas 23 is supplied to the reformer 3. The remainder of the exhaust gas 42 is supplied to the air preheater burner 62 as exhaust gas 45.

  On the other hand, the reformed gas 26 supplied from the reformer 3 is supplied to the CO shift converter 4 filled with a shift catalyst such as a copper-zinc catalyst, and is an exothermic reaction by the action of the shift catalyst (2) The aqueous shift reaction shown in FIG. Thereby, the carbon monoxide concentration of the reformed gas 26 is reduced to 1% or less. When the reformed gas 21 whose carbon monoxide concentration is reduced to 1% or less by the CO shift converter 4 is supplied to the hydrogen separator 53, the hydrogen separator 53 converts the hydrogen (high purity hydrogen) 58 in the reformed gas 21. To separate. The hydrogen separator 53 may be one that separates the hydrogen 58 in the reformed gas 21 using a hydrogen separation membrane such as a palladium membrane, and removes impurities in the reformed gas 21 using PSA for purification. Thus, the hydrogen 58 may be separated. When separating the hydrogen 58 in the reformed gas 21 by the hydrogen separator 53, the reformed gas 21 is boosted using a boosting means (not shown) as necessary in order to perform efficient hydrogen separation. .

  The hydrogen 58 separated by the hydrogen separator 53 is supplied to the hydrogen reservoir 59 and stored therein. The hydrogen storage 59 may be a hydrogen storage unit using a hydrogen storage alloy having a storage pressure of less than 1 MPa, or may be a high-pressure storage unit having a storage pressure of about 40 MPa. In storing the hydrogen 58 in the hydrogen storage 59, the pressure of the hydrogen 58 is increased using a pressure increasing means (not shown) as necessary.

  Further, since the exhaust gas 54 from which the hydrogen 58 has been separated from the reformed gas 21 by the hydrogen separator 53 contains hydrogen that has not been separated by the hydrogen separator 53, air is discharged together with the exhaust gases 44 and 45 as described above. It is supplied to the preheater burner 62. The air preheater burner 62 generates heat by burning the hydrogen in the exhaust gas 54 with the exhaust gases 44 and 45. The generated heat is heat exchanged with the air 14 by the air preheater 61, so that the air 39 to be supplied to the oxidant electrode 37 is warmed.

  In the hydrogen production system shown in FIG. 1, hydrogen is generated by the aqueous shift reaction shown in the formula (2) by reacting carbon monoxide in the reformed gas 26 with water vapor. Although the CO shift converter 4 is provided, the CO shift converter 4 is not necessarily provided and may be omitted if a decrease in the amount of hydrogen generation is allowed. When the CO shift converter 4 is omitted, the reformed gas 26 for the CO shift converter may be supplied to the hydrogen separator 53 as it is.

  In the hydrogen production system of the present embodiment, it is possible to store hydrogen in the hydrogen storage 59 at the same time as the power generation at a predetermined output by the solid oxide fuel cell 38 is continued. This is due to the following control.

  When the hydrogen storage amount detector 60 detects that the storage amount of the hydrogen storage 59 has decreased to a predetermined value, the oxidant electrode 37 of the solid oxide fuel cell 38 is controlled by controlling the opening degree of the flow control valve 43. The amount of supply of the natural gas 1 to the desulfurizer 2 is increased by controlling the opening amount of the flow control valve 27 while reducing the amount of supply of air 39 to the fuel cell, and used for power generation of the solid oxide fuel cell 38 The reformer 3 generates more hydrogen and carbon monoxide than the required amount.

  Further, the reformed gas 22 containing excess hydrogen and carbon monoxide generated in the reformer 3 is supplied to the CO shift converter 4 as the reformed gas 26 for the CO shift converter by opening the shut-off valve 79. Subsequently, carbon monoxide in the reformed gas 26 is reacted with water vapor to generate carbon dioxide and hydrogen, and the carbon monoxide concentration is reduced to 1% or less. The reformed gas 21 whose carbon monoxide concentration has been reduced to 1% or less by the reaction in the CO shift converter 4 is supplied to the hydrogen separator 53 to separate the hydrogen 58, and the hydrogen 58 is stored in the hydrogen reservoir 59. .

  When the supply amount of the natural gas 1 is increased, the endothermic amount due to the steam reforming reaction of the natural gas in the reformer 3 is increased. However, since the supply amount of the air 39 is decreased, the solid oxide fuel cell using the air 39 is reduced. The cooling of 38 is suppressed. As a result, the steam reforming reaction of the natural gas 1 corresponding to the increase in the supply amount of the exhaust heat of the solid oxide fuel cell 38 that has been discarded together with the exhaust gas 45 by the cooling by the air 39 until then. It can be used as heat of reaction. As a result, even if the supply amount of the natural gas 1 is increased, the reaction temperature of the solid oxide fuel cell 38 and the reformer 3 is prevented from decreasing, and the power generation performance of the solid oxide fuel cell 38 is decreased. There is nothing.

  Next, in the hydrogen production system of the present embodiment, a control method when the hydrogen storage amount returns to a predetermined value will be briefly described.

  When the hydrogen storage amount detector 60 detects that the storage amount of the hydrogen storage 59 has increased to a predetermined value, the oxidant electrode 37 of the solid oxide fuel cell 38 is controlled by controlling the opening of the flow control valve 43. The amount of supply of the natural gas 1 to the desulfurizer 2 is decreased by increasing the supply amount of the air 39 and controlling the opening degree of the flow control valve 27, and used for power generation of the solid oxide fuel cell 38. The amount of hydrogen and carbon monoxide to be generated is generated by the reformer 3. Further, the supply of the reformed gas 26 to the CO shift converter 4 is stopped by closing the shutoff valve 79, and the storage of the hydrogen 58 in the hydrogen storage 59 is stopped.

  When the supply amount of the natural gas 1 is decreased, the endothermic amount due to the steam reforming reaction of the natural gas in the reformer 3 is decreased. However, since the supply amount of the air 39 is increased, the solid oxide fuel by the air 39 is increased. Cooling of the battery 38 is promoted, and the exhaust heat of the solid oxide fuel cell 38 that has been used for the steam reforming reaction of the natural gas 1 can be released to the outside together with the exhaust gas 44. As a result, even if the supply amount of the natural gas 1 is reduced, the reaction temperature of the solid oxide fuel cell 38 and the reformer 3 is prevented from rising, and the reformer 3 and the solid oxide fuel cell 38 are It will not cause any degradation, nor will it reduce the lifetime or reliability of the system.

  In general, the oxygen utilization rate at the oxidant electrode 37 of the solid oxide fuel cell 38 is 20%, and most of the air 39 is used for cooling the solid oxide fuel cell 38. For this reason, even if the supply amount of the natural gas 1 as the fuel is increased or decreased, the supply amount of the air 39 is increased or decreased to maintain the reaction temperature of the solid oxide fuel cell 38 within a predetermined temperature range. The reaction heat required for the steam reforming reaction of the gas 1 can be ensured.

  In this embodiment, the reformed gas is supplied to the CO shift converter 4 from the fuel electrode 35 instead of the reformer 3.

  FIG. 2 is a block diagram showing an example of the configuration of the hydrogen production system of this embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 2, the hydrogen production system of the present embodiment does not include a pipe for supplying the reformed gas 26 from the reformer 3 to the CO shift converter 4 in the hydrogen production system shown in FIG. 1. Further, the pipe to which the exhaust gas 42 from the fuel electrode 35 is supplied is branched into three. Two of them are the same as the hydrogen production system shown in FIG. The remaining one is connected to the CO shift converter 4. By this piping, the exhaust gas 65 obtained by diverting the exhaust gas 42 from the fuel electrode 35 is supplied to the CO shift converter 4.

  A part of the exhaust gas 42 containing steam generated by the cell reaction in the fuel electrode 35 of the solid oxide fuel cell 38 is used to supply steam necessary for the steam reforming reaction of hydrocarbons in the reformer 3. The exhaust gas 41 is recycled to the reformer 3 and mixed with the desulfurized natural gas 24 to generate a mixed gas 23 of steam and desulfurized natural gas. The generated mixed gas 23 of steam and desulfurized natural gas is the reformer. 3 is supplied. The remainder is supplied to the air preheater burner 62 as the exhaust gas 45 for the air preheater burner or supplied to the CO shift converter 4 as the exhaust gas 65 for the CO shift converter.

  A shutoff valve 82 is provided in a pipe connecting the fuel electrode 35 and the air preheater burner 62, and a shutoff valve 81 is provided in a pipe connecting the fuel electrode 35 and the CO shift converter 4. The shut-off valves 81 and 82 are connected to the control unit 70 via a signal line (not shown), and open and close according to a control signal from the control unit 70.

  Next, with reference to FIG. 2, the control method of the hydrogen production system of a present Example is demonstrated.

  As described above, the hydrogen production system of this embodiment differs from the hydrogen production system shown in FIG. 1 in place of the reformed gas 26 supplied from the reformer 3 as the reformed gas for the CO shift converter. The difference is that the exhaust gas 65 from the fuel electrode 35 of the solid oxide fuel cell fuel 38 is used. The description will focus on the differences from the first embodiment.

  When the hydrogen storage amount detector 60 detects that the hydrogen storage amount of the hydrogen storage 59 has increased to a predetermined value, the cutoff valve 81 is closed and the cutoff valve 82 is opened by a control signal from the control unit 70. Thereby, the exhaust gas 45 is supplied to the air preheater burner 62. On the other hand, when the hydrogen storage amount detector 60 detects that the hydrogen storage amount of the hydrogen storage 59 has decreased to a predetermined value, the shut-off valve 81 is opened by the control signal from the control unit 70, and the shut-off valve 82 is close. As a result, the exhaust gas 65 is supplied to the CO shift converter 4.

  In the CO shift converter 4, the carbon monoxide concentration of the exhaust gas 65 is reduced to 1% or less by performing the aqueous shift reaction shown in the equation (2). The exhaust gas 66 with the carbon monoxide concentration reduced to 1% or less is supplied to the hydrogen separator 53, and the hydrogen separator 53 separates the hydrogen 58 from the exhaust gas 66. Since the exhaust gas 54 after the hydrogen 58 is separated from the exhaust gas 66 by the hydrogen separator 53 contains hydrogen that has not been separated by the hydrogen separator 53, the exhaust gas 54 is supplied to the air preheater burner 62.

  In the air preheater 61, when the hydrogen storage amount detector 60 detects that the hydrogen storage amount of the hydrogen storage device 59 has increased to a predetermined value, the exhaust gas 45 and the exhaust gas 44 are supplied to the air preheater burner 62. The air 39 is preheated by supplying and burning, and exchanging heat with the air 14 supplied to the air preheater 61. On the other hand, when the hydrogen storage amount detector 60 detects that the hydrogen storage amount of the hydrogen storage device 59 has decreased to a predetermined value, the exhaust gas 54 and the exhaust gas 44 are supplied to the air preheater burner 62 for combustion. The air 39 is preheated by exchanging heat with the air 14 supplied to the air preheater 61.

  In the hydrogen production system shown in FIG. 2, carbon monoxide in the exhaust gas 65 is reacted with water vapor to generate hydrogen by the aqueous shift reaction shown in the formula (2). Although the shift converter 4 is provided, the CO shift converter 4 is not necessarily provided and may be omitted if a reduction in the amount of hydrogen generation is allowed. When the CO shift converter 4 is omitted, the exhaust gas 65 may be supplied to the hydrogen separator 53 as it is.

  Also in the hydrogen production system of the present embodiment, it is possible to store hydrogen in the hydrogen storage 59 at the same time as the power generation at a predetermined output by the solid oxide fuel cell 38 is continued. That is, when the hydrogen storage amount detector 60 detects that the storage amount of the hydrogen storage device 59 has decreased to a predetermined value, the solid oxide fuel cell 38 is controlled by controlling the opening degree of the flow control valve 43. The amount of air 39 supplied to the oxidizer electrode 37 is decreased, and the amount of natural gas 1 supplied to the desulfurizer 2 is increased by controlling the opening degree of the flow control valve 27, so that the solid oxide fuel cell The reformer 3 generates more hydrogen and carbon monoxide than the amount used for generating 38 electric power.

  Further, the exhaust gas 42 containing excess hydrogen and carbon monoxide generated in the reformer 3 is supplied to the CO shift converter 4 as the exhaust gas 65 by opening the shut-off valve 81, and the solid oxide form for the CO shift converter Carbon monoxide and hydrogen are generated by reacting carbon monoxide in the fuel cell anode discharge gas 65 with water vapor, and the carbon monoxide concentration is reduced to 1% or less.

  When the exhaust gas 66 with the carbon monoxide concentration reduced to 1% or less generated by the CO shift converter 4 is supplied to the hydrogen separator 53, hydrogen 58 is separated from the exhaust gas 66, and this hydrogen 58 is stored in the hydrogen storage. Stored in vessel 59. When the supply amount of the natural gas 1 is increased, the endothermic amount due to the steam reforming reaction of the natural gas in the reformer 3 is increased. However, since the supply amount of the air 39 is decreased, the solid oxide fuel cell using the air 39 is reduced. The cooling of the gas 38 is suppressed, and the exhaust heat of the solid oxide fuel cell 38 that has been discarded together with the exhaust gas 44 by the cooling by the air 39 until then is supplied to the reformer 3 by the amount of the natural gas 1 corresponding to the increased supply amount. It can be used as heat of reaction for steam reforming reaction. As a result, even if the supply amount of the natural gas 1 is increased, the reaction temperature of the solid oxide fuel cell 38 and the reformer 3 is lowered, and the power generation performance of the solid oxide fuel cell 38 can be prevented from being lowered. .

  On the other hand, when the hydrogen storage amount detector 60 detects that the storage amount of the hydrogen storage device 59 has increased to a predetermined value, the solid oxide fuel cell 38 is controlled by controlling the opening degree of the flow control valve 43. The amount of the air 39 supplied to the oxidizer electrode 37 is increased, and the amount of the natural gas 1 supplied to the desulfurizer 2 is decreased by controlling the opening degree of the flow rate control valve 27, so that the solid oxide fuel cell The reformer 3 generates hydrogen and carbon monoxide in an amount to be used for power generation of 38.

  Further, by closing the shut-off valve 81, the supply of the exhaust gas 65 to the CO shift converter 4 is stopped, and the storage of the hydrogen 58 in the hydrogen reservoir 59 is stopped. When the supply amount of the natural gas 1 is decreased, the endothermic amount due to the steam reforming reaction of the natural gas in the reformer 3 is decreased. However, since the supply amount of the air 39 is increased, the solid oxide fuel cell using the air 39 is increased. 38 is accelerated, and the exhaust heat of the solid oxide fuel cell 38 that has been used for the steam reforming reaction of the natural gas 1 in the reformer 3 is released to the outside together with the exhaust gas 44. As a result, even if the supply amount of the natural gas 1 is reduced, the reaction temperature of the solid oxide fuel cell 38 and the reformer 3 is prevented from rising, and the reformer 3 and the solid oxide fuel cell 38 are It will not cause any degradation, nor will it reduce the lifetime or reliability of the system.

  In general, the oxygen utilization rate at the oxidant electrode 37 of the solid oxide fuel cell 38 is 20%, and most of the air 39 is used for cooling the solid oxide fuel cell 38. For this reason, even if the supply amount of the natural gas 1 as the fuel is increased or decreased, the supply amount of the air 39 is increased or decreased to maintain the reaction temperature of the solid oxide fuel cell 38 within a predetermined temperature range. The reaction heat required for the steam reforming reaction of the gas 1 can be ensured.

  In this example, the reformer 3 provided in Examples 1 and 2 is omitted, and a mixed gas of water vapor and desulfurized natural gas is supplied to the fuel electrode of the solid oxide fuel cell as it is, and the natural gas is supplied to the fuel electrode. A steam reforming reaction of hydrocarbons contained in the gas is performed.

  FIG. 3 is a block diagram showing a configuration example of the hydrogen production system according to the present embodiment. The same components as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, in the hydrogen production system of the present embodiment, the reformer 3 of the hydrogen production system shown in FIG. 2 is not provided, and the mixed gas 23 including the exhaust gas 68 and the desulfurized natural gas 24 is used. The supply pipe is connected to the fuel electrode 35.

  Next, with reference to FIG. 3, the control method of the hydrogen production system of a present Example is demonstrated.

  As described above, the hydrogen production system of this embodiment is different from the hydrogen production system shown in FIG. 2 in that the reformer 3 is not provided, and the mixed gas 23 of steam and desulfurized natural gas is used as it is as a solid oxide. The difference is that the fuel is supplied to the fuel electrode 35 of the fuel cell 38 and the fuel electrode 35 performs a steam reforming reaction of hydrocarbons contained in the natural gas 1. Differences from the second embodiment will be mainly described.

  As described above, the mixed gas 23 of water vapor and desulfurized natural gas is supplied to the fuel electrode 35 of the solid oxide fuel cell 38. In the fuel electrode 35 of the solid oxide fuel cell 38, a steam reforming reaction of hydrocarbons (mainly methane) contained in the natural gas 1 is performed by the action of the fuel electrode catalyst, and hydrogen and carbon monoxide are generated. . Hydrogen and carbon monoxide generated in the fuel electrode 35 are consumed on the spot by the fuel electrode reaction shown in the equations (3) and (4), and the solid oxide fuel cell 38 generates power. Since the hydrocarbon steam reforming reaction is an endothermic reaction, the heat generated by the solid oxide fuel cell 38 is used as the reaction heat necessary for the hydrocarbon steam reforming reaction.

  The power generation temperature of the solid oxide fuel cell 38 is generally 800 to 1000 ° C., and the power generation temperature is maintained by the heat generated by the cell reaction. Therefore, the heat generated by the solid oxide fuel cell 38 can be used as the reaction heat of the hydrocarbon steam reforming reaction at the fuel electrode 35 as described above. The steam necessary for the steam reforming reaction is to recycle the exhaust gas 68 containing the steam generated by the fuel electrode reaction shown in the formula (3) at the fuel electrode 35 of the solid oxide fuel cell 38 to the fuel electrode 35. Supplied by

  In the hydrogen production system shown in FIG. 3, carbon monoxide in the exhaust gas 65 is reacted with water vapor to generate hydrogen by the aqueous shift reaction shown in the formula (2). Although the shift converter 4 is provided, the CO shift converter 4 is not necessarily provided and may be omitted if a reduction in the amount of hydrogen generation is allowed. When the CO shift converter 4 is omitted, the exhaust gas 65 may be supplied to the hydrogen separator 53 as it is.

  In the hydrogen production system of the present embodiment, it is possible to store hydrogen in the hydrogen storage 59 at the same time as the power generation at a predetermined output by the solid oxide fuel cell 38 is continued. That is, when the hydrogen storage amount detector 60 detects that the storage amount of the hydrogen storage device 59 has decreased to a predetermined value, the solid oxide fuel cell 38 is controlled by controlling the opening degree of the flow control valve 43. The amount of air 39 supplied to the oxidizer electrode 37 is decreased, and the amount of natural gas 1 supplied to the desulfurizer 2 is increased by controlling the opening degree of the flow control valve 27, so that the solid oxide fuel cell More than the amount of hydrogen and carbon monoxide used for power generation 38 are generated at the fuel electrode 35 of the solid oxide fuel cell 38.

  Further, the exhaust gas 42 containing excess hydrogen and carbon monoxide generated at the fuel electrode 35 of the solid oxide fuel cell 38 is supplied to the CO shift converter 4 as the exhaust gas 65 by opening the shut-off valve 81 and discharged. Carbon monoxide and hydrogen are generated by reacting carbon monoxide in the gas 65 with water vapor, and the carbon monoxide concentration is reduced to 1% or less. The exhaust gas 66 generated by the CO shift converter 4 and having the carbon monoxide concentration reduced to 1% or less is supplied to the hydrogen separator 53, where hydrogen 58 is separated from the exhaust gas 66, and this hydrogen 58 is stored in the hydrogen storage. Stored in vessel 59. When the supply amount of the natural gas 1 is increased, the endothermic amount due to the steam reforming reaction of the natural gas in the fuel electrode 35 of the solid oxide fuel cell 38 is increased, but the supply amount of the air 39 is decreased. Of the solid oxide fuel cell 38 is suppressed by the natural gas 1, and the amount of exhaust heat of the solid oxide fuel cell 38 that has been discarded together with the exhaust gas 44 by the cooling of the air 39 until then is increased. It can be used as the heat of reaction for the steam reforming reaction. As a result, even if the supply amount of the natural gas 1 increases, the reaction temperature of the solid oxide fuel cell 38 does not decrease, and the power generation performance of the solid oxide fuel cell 38 does not decrease.

  On the other hand, when the hydrogen storage amount detector 60 detects that the storage amount of the hydrogen storage device 59 has increased to a predetermined value, the solid oxide fuel cell 38 is controlled by controlling the opening degree of the flow control valve 43. The amount of the air 39 supplied to the oxidizer electrode 37 is increased, and the amount of the natural gas 1 supplied to the desulfurizer 2 is decreased by controlling the opening degree of the flow rate control valve 27, so that the solid oxide fuel cell The amount of hydrogen and carbon monoxide used for power generation 38 is generated at the fuel electrode 35 of the solid oxide fuel cell 38.

  Further, by closing the shutoff valve 81, supply of the exhaust gas 65 generated at the fuel electrode 35 of the solid oxide fuel cell 38 to the CO shift converter 4 is stopped, and storage of the hydrogen 58 in the hydrogen storage 59 is stopped. . When the supply amount of the natural gas 1 is decreased, the endothermic amount due to the steam reforming reaction of the natural gas in the fuel electrode 35 of the solid oxide fuel cell 38 is decreased. However, the supply amount of the air 39 is increased, so that the air 39 is increased. Thus, the cooling of the solid oxide fuel cell 38 is promoted, and the exhaust heat of the solid oxide fuel cell 38 that has been used for the steam reforming reaction of the natural gas 1 is released to the outside together with the exhaust gas 44. As a result, even if the supply amount of the natural gas 1 is decreased, the reaction temperature of the solid oxide fuel cell 38 is prevented from rising, causing deterioration of the solid oxide fuel cell 38, system life and reliability. There will be no decline in sex.

  In general, the oxygen utilization rate at the oxidant electrode 37 of the solid oxide fuel cell 38 is 20%, and most of the air 39 is used for cooling the solid oxide fuel cell 38. For this reason, even if the supply amount of the natural gas 1 as the fuel is increased or decreased, the supply amount of the air 39 is increased or decreased to maintain the reaction temperature of the solid oxide fuel cell 38 within a predetermined temperature range. The reaction heat required for the steam reforming reaction of the gas 1 can be ensured.

  In the first to third embodiments, the solid oxide fuel cell 38 is used as the fuel cell. However, a molten carbonate fuel cell may be used instead of the solid oxide fuel cell 38. Good.

  Moreover, although the control part 70 was provided in the hydrogen storage 59, the installation place of the control part 70 is not limited to the hydrogen storage 59.

  The present invention is not limited to the above-described embodiment, and various modifications are of course added without departing from the spirit of the present invention.

It is a block diagram which shows one structural example of the hydrogen production system of Example 1 of this invention. It is a block diagram which shows one structural example of the hydrogen production system of Example 2 of this invention. It is a block diagram which shows one structural example of the hydrogen production system of Example 3 of this invention. It is a block diagram which shows the example of 1 structure of the conventional hydrogen production system.

Explanation of symbols

1, 32, 34, 70 Natural gas 2 Desulfurizer 3 Reformer 4 CO shift converter 5 Steam 6 Make-up water 7 Make-up water pump 8, 13, 17, 69, 75, 76, 77, 79, 81, 82 Shut-off valve DESCRIPTION OF SYMBOLS 9 Steam generator 10 Steam generator burner 11 Reformer starting burner 12 Air supply blower 14, 33, 39, 71, 72 Air 15, 18, 20, 27, 28, 40, 43, 47, 73, 74 , 78, 83 Flow control valve 19 Reformer burner 21, 22 Reformed gas 23 Mixed gas 24 Desulfurized natural gas 25 Reformed gas 26 Reformed gas 29, 30, 31, 41, 42, 44, 45, 54, 65 , 66, 68, 80 Exhaust gas 35 Fuel electrode 36 Solid oxide electrolyte 37 Oxidant electrode 38 Solid oxide fuel cell 48 Output regulator 49 Load 50 Fuel cell DC output 51 Transmission End AC output 53 hydrogen separator 58 hydrogen 59 hydrogen storage device 60 hydrogen storage quantity detector 61 the air preheater 62 air preheater burner 63 hydrogen supply equipment 64 hydrogen consuming means 65, 70 control unit

Claims (16)

A fuel reforming step of generating a reformed gas containing hydrogen from a fuel containing elemental hydrogen by an endothermic reaction;
Using the reformed gas and an oxidant to generate electricity and generate heat for the endothermic reaction;
A shift reaction step of converting carbon monoxide and water vapor in the reformed gas into hydrogen and carbon dioxide;
A hydrogen separation step of separating hydrogen from the hydrogen and gas containing carbon dioxide by the shift reaction step;
A hydrogen storage step for storing the hydrogen separated in the hydrogen separation step;
A hydrogen storage amount detection step for detecting a storage amount of the hydrogen to be stored;
The detection value by the hydrogen storage amount detection step is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is decreased and the supply amount of the fuel is increased by decreasing the supply amount of the oxidant. When the detected value of the means increases to a predetermined value, increasing the supply amount of the oxidant and decreasing the supply amount of the fuel;
A hydrogen production method comprising: A fuel reforming step of generating a reformed gas containing hydrogen from a fuel containing elemental hydrogen by an endothermic reaction;
Using the reformed gas and an oxidant to generate electricity and generate heat for the endothermic reaction;
A hydrogen separation step of separating hydrogen from the reformed gas;
A hydrogen storage step for storing the hydrogen separated in the hydrogen separation step;
A hydrogen storage amount detection step for detecting a storage amount of the hydrogen to be stored;
The detection value by the hydrogen storage amount detection step is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is decreased and the supply amount of the fuel is increased by decreasing the supply amount of the oxidant. When the detected value of the means increases to a predetermined value, increasing the supply amount of the oxidant and decreasing the supply amount of the fuel;
A hydrogen production method comprising: A fuel reforming step of generating a reformed gas containing hydrogen from a fuel containing elemental hydrogen by an endothermic reaction;
Using the reformed gas and an oxidant to generate heat and generate heat for the endothermic reaction, to generate a gas containing carbon monoxide and water vapor;
A shift reaction step of converting the carbon monoxide and the water vapor into hydrogen and carbon dioxide;
A hydrogen separation step of separating hydrogen from the hydrogen and gas containing carbon dioxide by the shift reaction step;
A hydrogen storage step for storing the hydrogen separated in the hydrogen separation step;
A hydrogen storage amount detection step for detecting a storage amount of the hydrogen to be stored;
The detection value by the hydrogen storage amount detection step is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is decreased and the supply amount of the fuel is increased by decreasing the supply amount of the oxidant. When the detected value of the means increases to a predetermined value, increasing the supply amount of the oxidant and decreasing the supply amount of the fuel;
A hydrogen production method comprising: A fuel reforming step of generating a reformed gas containing hydrogen from a fuel containing elemental hydrogen by an endothermic reaction;
Using the reformed gas and an oxidant to generate electricity and generate heat for the endothermic reaction to generate a gas containing hydrogen; and
A hydrogen separation step of separating hydrogen from the hydrogen-containing gas;
A hydrogen storage step for storing the hydrogen separated in the hydrogen separation step;
A hydrogen storage amount detection step for detecting a storage amount of the hydrogen to be stored;
The detection value by the hydrogen storage amount detection step is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is decreased and the supply amount of the fuel is increased by decreasing the supply amount of the oxidant. When the detected value of the means increases to a predetermined value, increasing the supply amount of the oxidant and decreasing the supply amount of the fuel;
A hydrogen production method comprising: Generating power using a fuel containing hydrogen element and an oxidant to generate a gas containing carbon monoxide and water vapor;
A shift reaction step of converting the carbon monoxide and water vapor of the gas containing carbon monoxide and water vapor into hydrogen and carbon dioxide;
A hydrogen separation step of separating hydrogen from the hydrogen and gas containing carbon dioxide by the shift reaction step;
A hydrogen storage step for storing the hydrogen separated in the hydrogen separation step;
A hydrogen storage amount detection step for detecting a storage amount of the hydrogen to be stored;
The detection value by the hydrogen storage amount detection step is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is decreased and the supply amount of the fuel is increased by decreasing the supply amount of the oxidant. When the detected value of the means increases to a predetermined value, increasing the supply amount of the oxidant and decreasing the supply amount of the fuel;
A hydrogen production method comprising: Generating electric power using a fuel containing hydrogen element and an oxidant to generate a gas containing hydrogen;
A hydrogen separation step of separating hydrogen from the hydrogen-containing gas;
A hydrogen storage step for storing the hydrogen separated in the hydrogen separation step;
A hydrogen storage amount detection step for detecting a storage amount of the hydrogen to be stored;
The detection value by the hydrogen storage amount detection step is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is decreased and the supply amount of the fuel is increased by decreasing the supply amount of the oxidant. When the detected value of the means increases to a predetermined value, increasing the supply amount of the oxidant and decreasing the supply amount of the fuel;
A hydrogen production method comprising: A hydrogen production method according to any one of claims 1 to 6,
A method for producing hydrogen, wherein the hydrogen storage amount detection means is a pressure detection means or a weight detection means. The hydrogen production method according to any one of claims 1 to 7,
A method for producing hydrogen, wherein the fuel cell is a solid oxide fuel cell or a molten carbonate fuel cell. A fuel reforming means for generating a reformed gas containing hydrogen from the fuel by an endothermic reaction when a fuel containing elemental hydrogen is supplied;
A fuel cell that generates electricity and generates heat for the endothermic reaction using the reformed gas and an oxidant;
When the reformed gas is supplied, shift reaction means for converting carbon monoxide and water vapor in the reformed gas into hydrogen and carbon dioxide;
Hydrogen separation means for separating hydrogen from the hydrogen and the exhaust gas containing carbon dioxide by the shift reaction means;
Hydrogen storage means for storing the hydrogen separated by the hydrogen separation means;
A hydrogen storage amount detection means for detecting a storage amount of the hydrogen stored in the hydrogen storage means;
The detection value by the hydrogen storage amount detection means is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is increased while the supply amount of the oxidant is decreased, and the detection value is A control unit that increases the supply amount of the oxidant and decreases the supply amount of the fuel,
A hydrogen production system. A fuel reforming means for generating a reformed gas containing hydrogen from the fuel by an endothermic reaction when a fuel containing elemental hydrogen is supplied;
A fuel cell that generates electricity and generates heat for the endothermic reaction using the reformed gas and an oxidant;
A hydrogen separation means for separating hydrogen in the reformed gas when the reformed gas is supplied;
Hydrogen storage means for storing the hydrogen separated by the hydrogen separation means;
A hydrogen storage amount detection means for detecting a storage amount of the hydrogen stored in the hydrogen storage means;
The detection value by the hydrogen storage amount detection means is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is increased while the supply amount of the oxidant is decreased, and the detection value is A control unit that increases the supply amount of the oxidant and decreases the supply amount of the fuel,
A hydrogen production system. A fuel reforming means for generating a reformed gas containing hydrogen from the fuel by an endothermic reaction when a fuel containing elemental hydrogen is supplied;
A fuel cell for generating power and generating heat for the endothermic reaction using the reformed gas and an oxidant to generate carbon monoxide and water vapor;
When an exhaust gas containing the carbon monoxide and the water vapor is supplied from the fuel cell, shift reaction means for converting the carbon monoxide and water vapor in the exhaust gas into hydrogen and carbon dioxide,
A hydrogen separation means for separating the hydrogen in the exhaust gas containing the hydrogen and the carbon dioxide by the shift reaction means;
Hydrogen storage means for storing the hydrogen separated by the hydrogen separation means;
A hydrogen storage amount detection means for detecting a storage amount of the hydrogen stored in the hydrogen storage means;
The detection value by the hydrogen storage amount detection means is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is increased while the supply amount of the oxidant is decreased, and the detection value is A control unit that increases the supply amount of the oxidant and decreases the supply amount of the fuel,
A hydrogen production system. A fuel reforming means for generating a reformed gas containing hydrogen from the fuel by an endothermic reaction when a fuel containing elemental hydrogen is supplied;
A fuel cell that generates heat and gas for generating heat and generating heat for the endothermic reaction using the reformed gas and an oxidant;
Hydrogen separation means for separating hydrogen in the exhaust gas when the exhaust gas containing the hydrogen is supplied from the fuel cell;
Hydrogen storage means for storing the hydrogen separated by the hydrogen separation means;
A hydrogen storage amount detection means for detecting a storage amount of the hydrogen stored in the hydrogen storage means;
The detection value by the hydrogen storage amount detection means is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is increased while the supply amount of the oxidant is decreased, and the detection value is A control unit that increases the supply amount of the oxidant and decreases the supply amount of the fuel,
A hydrogen production system. When a fuel containing an elemental hydrogen and an oxidant are supplied, a fuel cell that generates power using the fuel and the oxidant to generate a gas containing carbon monoxide and water vapor;
When an exhaust gas containing the carbon monoxide and the water vapor is supplied from the fuel cell, shift reaction means for converting the carbon monoxide and water vapor in the exhaust gas into hydrogen and carbon dioxide,
Hydrogen separation means for separating hydrogen from the exhaust gas containing hydrogen and carbon dioxide by the shift reaction means;
Hydrogen storage means for storing the hydrogen separated by the hydrogen separation means;
A hydrogen storage amount detection means for detecting a storage amount of the hydrogen stored in the hydrogen storage means;
The detection value by the hydrogen storage amount detection means is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is increased while the supply amount of the oxidant is decreased, and the detection value is A control unit that increases the supply amount of the oxidant and decreases the supply amount of the fuel,
A hydrogen production system. A fuel cell that, when supplied with a fuel containing hydrogen element and an oxidant, generates power using the fuel and the oxidant to generate a gas containing hydrogen;
Hydrogen separation means for separating hydrogen in the exhaust gas when the exhaust gas containing the hydrogen is supplied from the fuel cell;
Hydrogen storage means for storing the hydrogen separated by the hydrogen separation means;
A hydrogen storage amount detection means for detecting a storage amount of the hydrogen stored in the hydrogen storage means;
The detection value by the hydrogen storage amount detection means is monitored, and when the detection value decreases below a predetermined value, the supply amount of the fuel is increased while the supply amount of the oxidant is decreased, and the detection value is A control unit that increases the supply amount of the oxidant and decreases the supply amount of the fuel,
A hydrogen production system. The hydrogen production system according to any one of claims 9 to 14,
A hydrogen production system, wherein the hydrogen storage amount detection means is a pressure detection means or a weight detection means. The hydrogen production system according to any one of claims 9 to 15,
A hydrogen production system, wherein the fuel cell is a solid oxide fuel cell or a molten carbonate fuel cell.

Images