JP2008115430A - Hydrogen production apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce heat loss and improve energy efficiency by reducing an amount of heat exchange occurring when a supply gas is heated and an outlet gas is cooled. <P>SOLUTION: An apparatus for producing hydrogen, which has an electrolyte layer containing an electrolyte, a hydrogen pole that is installed on one side of the electrolyte layer and produces hydrogen by electrolyzing vapor, and an oxygen pole that is installed on the other side of the electrolyte layer and produces oxygen, comprises: an electrochemical cell 1 which is made from a ceramic; a supply line 15a for an inlet of a hydrogen pole, which supplies a supply gas containing vapor for the inlet of the hydrogen pole to the electrochemical cell 1; an outlet line 11a in a hydrogen pole side, which discharges an outlet gas 11 containing hydrogen in the electrochemical cell 1 at a hydrogen pole; a pressure regulation mechanism 3 which is installed in the supply line 15a for the inlet of the hydrogen pole and adjusts a pressure of the supply gas for the inlet of the hydrogen pole; a circulation gas absorption mechanism 2 which supplies a part of the outlet gas at the hydrogen pole to the supply line 15a for the inlet of the hydrogen pole or the pressure regulation mechanism 3, as a circulation gas; and a cooler 5 that produces hydrogen by separating surplus water from the outlet gas 11 at the hydrogen pole, which does not circulate as a circulation gas. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrogen production apparatus and method for producing hydrogen by electrolyzing water at a high temperature.

  As one vision of the future society, the realization of a hydrogen energy society using hydrogen as an energy medium is attracting attention, and several promising hydrogen production methods are considered. Among several hydrogen production methods, high-temperature steam electrolysis can produce hydrogen with high efficiency by electrolyzing water at a high temperature as compared with electrolysis of water at room temperature.

This high-temperature steam electrolysis is an energy-efficient hydrogen production method in which, for example, if water vapor is electrolyzed at a high temperature of about 900 ° C., the same hydrogen production amount can be obtained with about 30% less electric power than water electrolysis at room temperature. It is. Since the operating temperature matches the operating temperature of the high-temperature gas reactor and fast breeder reactor, if these reactors are used as heat sources, the raw material is water, so that hydrogen can be produced without exhausting any carbon dioxide. Therefore, it is very promising as a clean hydrogen production technology that does not emit CO ₂ .

  FIG. 5 is a configuration diagram showing a configuration of a conventional high-temperature steam electrolysis system (hydrogen electrode side).

  As shown in the figure, the raw material water 7 is heated by the heater 4 and evaporated to form water vapor, which is supplied to the hydrogen electrode of the electrochemical cell 1. The hydrogen electrode outlet gas 11 of the electrochemical cell 1 is cooled via the cooler 5. In the steam / water separator 41 existing downstream of the cooler 5, moisture is separated from the hydrogen electrode outlet gas 11 to become circulating water 14. This circulating water 14 is returned to the raw water 7 via the water circulation pump 6.

  The hydrogen gas from which moisture has been removed in the steam separator 41 is introduced into the hydrogen separator 42 to become product hydrogen 8. In this steam / water separator 41, a part of the hydrogen gas separated and introduced is returned to the raw water 7 as the circulating gas 12 for keeping the hydrogen electrode in a reducing atmosphere.

  The introduced circulating gas 12 is heated by the heater 4 together with the raw water 7 and supplied to the hydrogen electrode of the electrochemical cell 1 as the hydrogen electrode inlet supply gas 20. On the other hand, on the oxygen electrode side, an oxygen electrode supply gas 51 with a reduced oxygen partial pressure is supplied through an oxygen electrode supply line 51a, and after the oxygen rich gas generated in the electrochemical cell 1 is cooled, It is discharged out of the system via the oxygen electrode outlet line 52a.

  In the above-described hydrogen production by high-temperature steam electrolysis, the minimum unit is a cell. The cell basically has a three-layer structure in which an electrolyte is placed in the middle and an oxygen electrode (anode) and a hydrogen electrode (cathode) are arranged on both sides of the electrolyte layer. Electrons are given at the hydrogen electrode to decompose water vapor into oxygen ions and hydrogen. The decomposed oxygen ions permeate the electrolyte layer and release electrons at the oxygen electrode to generate oxygen. The electrolyte layer, oxygen electrode, and hydrogen electrode are made of ceramics to withstand use at high temperatures.

  Among these three-layer structures, the hydrogen electrode uses a cermet of an active metal and ceramics that have a catalytic action for the reaction of decomposing water vapor into oxygen ions and hydrogen. In order to maintain the activity of the hydrogen electrode (reaction activity for decomposing water vapor into oxygen ions and hydrogen), it is necessary to maintain a reducing atmosphere so as to suppress oxidation of the active metal. For this reason, it is desirable to mix hydrogen gas in addition to water vapor into the supply gas to the hydrogen electrode.

  As a hydrogen gas to be supplied to the hydrogen electrode in order to establish a closed system in which only water, electricity and heat are supplied to the high-temperature steam electrolysis system in order to maintain the reducing atmosphere so as to suppress oxidation of the active metal of the hydrogen electrode. A part of the hydrogen gas generated at the hydrogen electrode can be used.

  The components of the hydrogen electrode outlet gas are hydrogen and unreacted water vapor, and this temperature is the temperature of a heat source (500 to 900 ° C.) used for the electrolytic reaction. This hydrogen electrode outlet gas is cooled by heat exchange with the hydrogen electrode supply gas. The cooled hydrogen electrode outlet gas is supposed to circulate the hydrogen gas to the supply side to the hydrogen electrode via a gas circulator after the moisture is condensed and separated. It is assumed that the condensed water is also circulated to the supply side.

Moreover, the technique which operates a steam turbine with the heat | fever which hydrogen-rich steam etc. which are taken out from a high temperature steam electrolysis cell have been known (for example, refer patent document 1). Here, power is generated by operating a steam turbine with the heat of hydrogen-enriched steam and oxygen-enriched air taken out from the high-temperature steam electrolysis cell, and electrolysis is performed in the high-temperature steam electrolysis cell using the generated electricity, Hydrogen is obtained from hydrogen-enriched water vapor after heat is applied.
Japanese Patent Application Laid-Open No. 06-93481

  In the above-described conventional hydrogen production by high-temperature steam electrolysis, in order to maintain the activity of the hydrogen electrode (reaction activity for decomposing water vapor into oxygen ions and hydrogen), it is necessary to maintain a reducing atmosphere to suppress oxidation of the active metal. is there. For this reason, it is desirable to mix hydrogen gas in addition to water vapor into the gas supplied to the hydrogen electrode. As described above, in order to establish a closed system in which the supply to the high-temperature steam electrolysis system is produced only with water, electricity, and heat, it is necessary to suppress oxidation of the active metal of the hydrogen electrode. In order to suppress this oxidation and maintain a reducing atmosphere, a part of the hydrogen gas generated at the hydrogen electrode can be used as the hydrogen gas supplied to the hydrogen electrode. The components of the hydrogen electrode outlet gas are hydrogen and unreacted water vapor, and the temperature is an electrolysis reaction temperature (500 to 900 ° C.). It is assumed that the hydrogen electrode outlet gas is cooled by heat exchange with the hydrogen electrode supply gas, moisture is condensed and separated, and then the hydrogen gas is circulated to the supply side to the hydrogen electrode by a gas circulator. Condensed water is also circulated to the supply side.

  At this time, with heat exchange between the cooling of the hydrogen electrode outlet gas and the heating of the supply gas, heat loss occurs and there is a problem in reducing the energy efficiency required for hydrogen production. That is, the cooling device 5 cools the entire amount of the hydrogen electrode outlet gas, and the heating device 4 has a relatively large amount of heat exchange to heat the cooled circulating water and the circulating gas to the hydrogen electrode supply gas condition. There was a problem where the heat loss caused by.

  The present invention has been made in order to solve the above-mentioned problems, and can reduce the heat exchange amount of the heating of the supply gas and the cooling of the outlet gas, and can reduce the heat loss, so that the hydrogen production can improve the energy efficiency. An object is to provide an apparatus and a method thereof.

  In order to achieve the above object, in the hydrogen production apparatus of the present invention, an electrolyte layer containing an electrolyte, a hydrogen electrode provided on one surface of the electrolyte layer to electrolyze water vapor to produce hydrogen, and the other surface of the electrolyte layer An electrochemical cell that is provided and has an oxygen electrode for producing oxygen and is made of ceramics; a hydrogen electrode inlet supply line that supplies the electrochemical cell with a hydrogen electrode inlet supply gas containing water vapor; and the electrochemical cell A hydrogen electrode side outlet line for discharging the hydrogen electrode outlet gas containing hydrogen, a pressure adjusting mechanism for adjusting the pressure of the hydrogen electrode inlet supply gas interposed in the hydrogen electrode inlet supply line, and the hydrogen electrode inlet line or A circulation gas suction mechanism for sucking and supplying a part of the hydrogen electrode outlet gas to the pressure adjusting mechanism as a circulation gas, and a surplus from the hydrogen electrode outlet gas not circulated as the circulation gas A cooler for producing hydrogen by water cooling separation, is characterized in that it comprises a.

  In order to achieve the above object, in the hydrogen production apparatus of the present invention, an electrolyte layer containing an electrolyte, a hydrogen electrode provided on one surface of the electrolyte layer to produce hydrogen by electrolyzing water vapor, and the electrolyte layer An electrochemical cell made of ceramics and provided with an oxygen electrode for producing oxygen; an oxygen electrode inlet supply line for supplying an oxygen electrode inlet supply gas containing oxygen to the electrochemical cell; An oxygen electrode side outlet line for discharging the oxygen electrode outlet gas containing oxygen in the chemical cell; a pressure adjusting mechanism for adjusting the pressure of the oxygen electrode inlet supply gas interposed in the oxygen electrode inlet supply line; and the oxygen electrode inlet A circulating gas suction mechanism for sucking and supplying a part of the oxygen electrode outlet gas as a circulating gas to the line or the pressure adjusting mechanism, and the oxygen electrode outlet gas not circulating as the circulating gas. A cooler for producing oxygen by separating cooled excessive water, is characterized in that it comprises a.

  In order to achieve the above object, in the hydrogen production method of the present invention, hydrogen is produced by electrolyzing water vapor at a hydrogen electrode provided on one surface of an electrolyte layer containing an electrolyte constituting an electrochemical cell, Producing oxygen at an oxygen electrode provided on the other surface of the electrolyte layer, supplying a hydrogen electrode inlet supply gas containing water vapor to the electrochemical cell via a hydrogen electrode inlet supply line, and the electrochemical A step of discharging the hydrogen electrode outlet gas containing hydrogen of the cell through the hydrogen electrode side outlet line, and adjusting the pressure of the hydrogen electrode inlet supply gas interposed in the hydrogen electrode inlet supply line via a pressure adjusting mechanism. A pressure adjusting mechanism step, and a step of supplying a part of the hydrogen electrode outlet gas as a circulating gas to the hydrogen electrode inlet line or the pressure adjusting mechanism via a circulating gas suction mechanism. And-up, is characterized in that it comprises the steps of producing the cooled separated hydrogen through the cooler excessive water of the hydrogen electrode outlet gas does not circulate as the circulation gas.

  According to the hydrogen production apparatus and the method of the present invention, a part of the hydrogen electrode outlet gas is circulated to the hydrogen electrode supply side without cooling, and the hydrogen electrode outlet is provided on the suction side of an ejector using this supply gas as a drive source By partially branching and connecting the gas, the heat exchange amount for heating the supply gas and cooling the outlet gas can be reduced and the heat loss can be reduced, so that energy efficiency can be improved.

  Hereinafter, embodiments of a hydrogen production apparatus and method according to the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

  FIG. 1 is a configuration diagram showing a high-temperature steam electrolysis system (hydrogen electrode side) according to a first embodiment of the present invention.

  As shown in the figure, the raw material water 7 is heated by the heater 4 and evaporated to form water vapor, which is supplied to the hydrogen electrode of the electrochemical cell 1. The electrochemical cell 1 has a three-layer structure in which an electrolyte is placed in the middle and an oxygen electrode (anode) and a hydrogen electrode (cathode) are arranged on both surfaces of the electrolyte layer. Electrons are given at the hydrogen electrode to decompose water vapor into oxygen ions and hydrogen. The decomposed oxygen ions permeate the electrolyte layer and release electrons at the oxygen electrode to generate oxygen. The electrolyte layer, the oxygen electrode, and the hydrogen electrode are made of ceramics to withstand use at high temperatures.

  The hydrogen electrode outlet gas 11 containing hydrogen of the electrochemical cell 1 is introduced into the cooler 5 through the hydrogen electrode outlet line 11a. In this cooler 5, the hydrogen electrode outlet gas 11 is cooled, and moisture in the gas is condensed to become circulating water 14. This circulating water 14 is supplied by the water circulation pump 6 and merges with the raw water 7 to become raw water and circulating water 15. The raw water and the circulating water 15 are introduced into the heater 4 through the hydrogen electrode inlet line 15a. In the heater 4, the introduced raw water and circulating water 15 are heated and evaporated to become water vapor 16.

  The water vapor partially branched from the water vapor 16 is introduced into the circulating gas suction mechanism 2. The branched water vapor 16 becomes the circulation gas suction mechanism driving water vapor 17 and is used as a driving source. In the circulating gas suction mechanism 2, the steam 17 for driving the circulating gas suction mechanism is used as a driving source to suck a part of the hydrogen electrode outlet gas 11 as the circulating gas 12.

  In the present embodiment configured as described above, the sucked circulating gas 12 merges with the circulating gas suction mechanism driving steam 17 to become steam and the circulating gas 19 and is introduced into the pressure adjusting mechanism 3. In the pressure adjusting mechanism 3, the water vapor and the circulating gas 19 are pressure-adjusted together with the water vapor 18 at the outlet of the heater 4, and are supplied to the hydrogen electrode of the electrochemical cell 1 as the hydrogen electrode inlet supply gas 20. The pressure adjusting mechanism 3 has a function of adjusting the water vapor and the circulating gas 19 and the water vapor 18 at the outlet of the heater 4 to a predetermined pressure. Hydrogen-rich gas generated at the hydrogen electrode of the electrochemical cell 1 is obtained as the hydrogen electrode outlet gas 11. The gas obtained by separating the circulation gas 12 from the hydrogen electrode outlet gas 11 becomes the product hydrogen and the circulation water 13 and is cooled by the cooler 5, and the water is condensed and separated as the circulation water 14 to obtain the product hydrogen 8.

  According to the present embodiment, a part of the hydrogen electrode outlet gas 11 is branched without cooling, and a mixed gas of water vapor and hydrogen is supplied as a circulation gas to the hydrogen electrode inlet, thereby reducing the amount of circulating water, The amount of heat exchange between the cooler 5 at the hydrogen electrode outlet and the heater 4 at the hydrogen electrode inlet can be reduced.

  In the conventional cooler 5, the water vapor and hydrogen gas at the outlet of the hydrogen electrode are all cooled, and the circulating water and the circulating gas cooled in the heater 4 are heated to the hydrogen electrode supply gas condition. In contrast, by circulating a part of the hydrogen electrode outlet gas to the supply side to the hydrogen electrode without cooling, the heat exchange amount of heating of the supply gas and cooling of the outlet gas is reduced, and heat loss is greatly increased. Therefore, energy efficiency can be greatly improved.

  Further, since the heat exchange amount is small, the heat exchanger can be downsized, the gas circulator becomes unnecessary, and the device manufacturing cost can be reduced.

  The electrochemical cell 1 may be any one of the open-ended cylindrical electrolytic cell 1a shown in FIG. 2, the open-ended cylindrical electrolytic cell 1b shown in FIG. 3, and a flat plate (not shown) electrochemical cell. Can also be used.

  The open-ended cylindrical electrolytic cell 1a includes a hydrogen electrode A forming a cylindrical inner side with both ends open, a cylindrical oxygen electrode B provided outside the hydrogen electrode, and the hydrogen electrode and oxygen. And an electrolyte layer C including an electrolyte provided between the electrodes. Steam can be supplied from one end of the open-ended cylindrical electrolytic cell 1a to the hydrogen electrode, and hydrogen-rich gas can be obtained from the other end.

  The one-end open type cylindrical electrolytic cell 1b includes a hydrogen electrode A that forms a cylindrical inner side with one end closed and the other end opened, a cylindrical oxygen electrode B provided outside the hydrogen electrode, An electrolyte layer C including an electrolyte is provided between the hydrogen electrode and the oxygen electrode. Hydrogen rich gas can be obtained by supplying water vapor to the hydrogen electrode via a water vapor introducing tube.

  FIG. 4 is a configuration diagram showing the configuration of the high-temperature steam electrolysis system (hydrogen electrode side) according to the second embodiment of the present invention. In this figure, an ejector 30 is provided in place of the circulating gas suction mechanism 2 in FIG. 1, and the same or similar parts as in FIG.

  As shown in this figure, the raw material water 7 joins with the circulating water 14 separated by the hydrogen electrode outlet line 11a, and becomes the raw water and the circulating water 15. The raw water and circulating water 15 are heated by the heater 4 and evaporated to become water vapor 16. The circulating gas suction mechanism driving steam 17 partially branched from the steam 16 is introduced into an ejector 30 which is a kind of the circulating gas suction mechanism 2 shown in FIG. Here, the water vapor 17 for driving the circulating gas suction mechanism is used as a driving source, and a negative pressure is generated inside the ejector 30, whereby a part of the hydrogen electrode outlet gas 11 is sucked as the circulating gas 12. The suctioned circulating gas 12 and the circulating gas suction mechanism driving steam 17 are combined to form steam and the circulating gas 19 and introduced into the hydrogen electrode inlet supply gas merging portion 21.

  On the other hand, the steam 18 at the outlet of the heater 4 drops in pressure through an orifice 31 which is a kind of the pressure adjusting mechanism 3 shown in FIG. 1, reaches the hydrogen electrode inlet supply gas merging portion 21, and merges with the steam and the circulating gas 19. . By the action of the orifice 31 having an appropriate diameter, the pressure of the water vapor 18 at the outlet of the heater 4 is set to a pressure approximately equal to the pressure of the water vapor and the circulating gas 19.

  In the present embodiment configured as described above, the hydrogen-rich gas generated at the hydrogen electrode of the electrochemical cell 1 is obtained as the hydrogen electrode outlet gas 11. The gas obtained by separating the circulating gas 12 from the hydrogen electrode outlet gas 11 becomes product hydrogen and circulating water 13 and is cooled by the cooler 5. In this cooler 5, the product hydrogen and the moisture contained in the circulating water 13 are condensed and separated as the circulating water 14, and the product hydrogen 8 is obtained.

  According to the present embodiment, a part of the hydrogen electrode outlet gas 11 is branched without being cooled, and a mixed gas of water vapor and hydrogen is supplied as the circulation gas 12 to the hydrogen electrode inlet. An ejector 30 using a part of the gas supplied to the hydrogen electrode as a drive source is installed on the hydrogen electrode supply side. By branching and connecting a part of the hydrogen electrode outlet gas to the suction side of the ejector 30, the amount of circulating water via the cooler 5 can be significantly reduced. This reduction in the amount of circulating water greatly reduces the amount of heat exchange in the cooler 5 at the hydrogen electrode outlet and the heater 4 at the hydrogen electrode inlet, contributing to energy efficiency improvement and further reducing the device manufacturing cost. Can do.

  Moreover, in a unit in which a large number of electrochemical cells are integrated, a part having a large pressure loss such as the orifice 31 is inserted into the gas supply line to each cell, and the supply gas flow rate to each cell is made uniform. It can contribute to energy efficiency improvement.

  A high temperature steam electrolysis system according to a third embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 5, in the conventional example, an oxygen electrode supply gas 51 with a reduced oxygen partial pressure is supplied to the oxygen electrode side of the electrochemical cell 1. The oxygen-rich gas produced in the electrochemical cell 1 is discharged out of the system as the oxygen electrode outlet gas 52 after cooling.

  In the present embodiment, the oxygen electrode inlet supply gas 51 containing oxygen is supplied to the oxygen electrode of the electrochemical cell 1 through the oxygen electrode inlet supply line 51a. The oxygen electrode outlet of the electrochemical cell 1 is connected to an oxygen electrode side outlet line 52a for discharging the produced oxygen electrode outlet gas containing oxygen.

  The oxygen electrode inlet supply line 51a is provided with a pressure adjusting mechanism (not shown) having the same function as the pressure adjusting mechanism 3 shown in FIG. The pressure of the oxygen electrode inlet supply gas 51 is adjusted by this pressure adjustment mechanism. The oxygen electrode inlet line 51a or the pressure adjusting mechanism is provided with a circulating gas suction mechanism (not shown) having the same function as the circulating gas suction mechanism 2 shown in FIG. This circulating gas suction mechanism supplies a part of the oxygen electrode outlet gas 52 to the oxygen electrode inlet supply gas 51 as a circulating gas. In addition, a cooler (not shown) for separating the excess water from the non-circulating oxygen electrode outlet gas 52 to produce oxygen is provided.

  According to the present embodiment, the oxygen electrode inlet supply line 51a is also provided with a pressure adjusting mechanism and a circulating gas suction mechanism having the same functions as those provided in the hydrogen electrode inlet line 15a of FIG. Oxygen generated by high-temperature steam electrolysis in the cell 1 is also recovered as a product. As the supply gas on the oxygen electrode side, a gas whose oxygen partial pressure is adjusted with water vapor is used. Oxygen can be obtained as a product by removing moisture from the oxygen-rich oxygen electrode outlet gas having a high oxygen partial pressure.

  As described above, in addition to the effects of energy efficiency improvement and device manufacturing cost reduction shown in the hydrogen production apparatuses of the first and second embodiments, a system that can make oxygen a product and has a large cost merit. realizable.

  Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention by combining the embodiments of the present invention. it can.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the high temperature steam electrolysis system (hydrogen electrode side) of the 1st Embodiment of this invention. FIG. 2 is a structural diagram and a hydrogen production principle diagram showing the cylindrical electrolytic cell (both ends open type) of FIG. 1. FIG. 2 is a structural diagram and a hydrogen production principle diagram showing the cylindrical electrolytic cell (one-end open type) of FIG. 1. The block diagram which shows the structure of the high temperature steam electrolysis system (hydrogen electrode side) of the 2nd Embodiment of this invention. The block diagram which shows the structure of the conventional high temperature steam electrolysis system (hydrogen-electrode side).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electrochemical cell, 1a ... Cylindrical electrolytic cell of open both ends, 1b ... Cylindrical electrolytic cell of open one end, 2 ... Circulating gas suction mechanism, 3 ... Pressure adjustment mechanism, 4 ... Heater, 5 ... Cooler , 6 ... Water circulation pump, 7 ... Raw water, 8 ... Product hydrogen, 11 ... Hydrogen electrode outlet gas, 11a ... Hydrogen electrode outlet line, 12 ... Circulating gas, 13 ... Product hydrogen and circulating water, 14 ... Circulating water, 15 ... Raw material water and circulating water, 15a ... Hydrogen electrode inlet supply line, 16 ... Water vapor, 17 ... Water vapor for driving circulating gas suction mechanism, 18 ... Water vapor, 19 ... Water vapor and circulating gas, 20 ... Hydrogen electrode inlet supply gas, 21 ... Hydrogen Electrode inlet supply gas merging section, 30 ... Ejector (circulation gas suction mechanism), 31 ... Orifice (pressure adjustment mechanism), 41 ... Gas-water separator, 42 ... Hydrogen separator, 51 ... Oxygen electrode inlet supply gas, 51a ... Oxygen Pole inlet supply line, 5 ... oxygen electrode exit gas, 52a ... oxygen electrode outlet line.

Claims (11)

An electrolyte layer including an electrolyte, a hydrogen electrode that is provided on one surface of the electrolyte layer and that produces hydrogen by electrolyzing water vapor, and an oxygen electrode that is provided on the other surface of the electrolyte layer and that produces oxygen are manufactured from ceramics. An electrochemical cell,
A hydrogen electrode inlet supply line for supplying a hydrogen electrode inlet supply gas containing the water vapor to the electrochemical cell;
A hydrogen electrode outlet line for discharging the hydrogen electrode outlet gas containing the hydrogen of the electrochemical cell;
A pressure adjusting mechanism for adjusting the pressure of the hydrogen electrode inlet supply gas interposed in the hydrogen electrode inlet supply line;
A circulation gas suction mechanism for sucking and supplying a part of the hydrogen electrode outlet gas as a circulation gas to the hydrogen electrode inlet line or the pressure adjusting mechanism;
A cooler that cools and separates excess water from the hydrogen electrode outlet gas that does not circulate as this circulating gas, and produces hydrogen;
A hydrogen production apparatus comprising:   2. The hydrogen production apparatus according to claim 1, wherein the circulating gas suction mechanism circulates as the hydrogen electrode inlet supply gas without cooling the hydrogen electrode side outlet gas. An electrolyte layer containing an electrolyte, a hydrogen electrode that is provided on one surface of the electrolyte layer to produce hydrogen by electrolyzing water vapor, and an oxygen electrode that is provided on the other surface of the electrolyte layer to produce oxygen, are made of ceramics. An electrochemical cell,
An oxygen electrode inlet supply line for supplying an oxygen electrode inlet supply gas containing oxygen to the electrochemical cell;
An oxygen electrode outlet line for discharging the oxygen electrode outlet gas containing the oxygen of the electrochemical cell;
A pressure adjusting mechanism for adjusting the pressure of the oxygen electrode inlet supply gas interposed in the oxygen electrode inlet supply line;
A circulating gas suction mechanism for sucking and supplying a part of the oxygen electrode outlet gas as a circulating gas to the oxygen electrode inlet line or the pressure adjusting mechanism;
A cooler that cools and separates excess water from the oxygen electrode outlet gas that does not circulate as the circulating gas, and produces oxygen;
A hydrogen production apparatus comprising:   4. The hydrogen production apparatus according to claim 3, wherein the circulating gas suction mechanism circulates as the oxygen electrode inlet supply gas without cooling the oxygen electrode side outlet gas.   4. The hydrogen production apparatus according to claim 1, wherein the circulation gas suction mechanism uses, as a drive source, water vapor generated by heating raw water supplied to the hydrogen electrode.   4. The hydrogen production apparatus according to claim 1, wherein the circulating gas suction mechanism includes an ejector that uses heated steam as a drive source.   The hydrogen production apparatus according to claim 1, wherein the pressure adjusting mechanism includes an orifice for lowering pressure.   The electrochemical cell includes a hydrogen electrode forming a cylindrical inner side with both ends open, a cylindrical oxygen electrode provided outside the hydrogen electrode, and an electrolyte provided between the hydrogen electrode and the oxygen electrode. 4. The hydrogen production apparatus according to claim 1, wherein water vapor is supplied from one end of the cell to the hydrogen electrode and hydrogen rich gas is obtained from the other end.   The electrochemical cell includes a hydrogen electrode forming a cylindrical inner side with one end closed and the other end opened, a cylindrical oxygen electrode provided outside the hydrogen electrode, and a gap between the hydrogen electrode and the oxygen electrode. The hydrogen production apparatus according to claim 1, further comprising: an electrolyte layer that includes an electrolyte and a water vapor introduction pipe that supplies water vapor to the hydrogen electrode to obtain a hydrogen-rich gas.   The hydrogen production apparatus according to claim 1, wherein the electrochemical cell has a flat plate structure. Producing hydrogen by electrolyzing water vapor at a hydrogen electrode provided on one surface of an electrolyte layer containing an electrolyte constituting an electrochemical cell, and producing oxygen at an oxygen electrode provided on the other surface of the electrolyte layer; ,
Supplying a hydrogen electrode inlet supply gas containing the water vapor to the electrochemical cell via a hydrogen electrode inlet supply line;
Discharging a hydrogen electrode outlet gas containing the hydrogen of the electrochemical cell via a hydrogen electrode side outlet line;
A pressure adjusting mechanism step for adjusting the pressure of the hydrogen electrode inlet supply gas via the pressure adjusting mechanism interposed in the hydrogen electrode inlet supply line;
Supplying a part of the hydrogen electrode outlet gas as a circulating gas to the hydrogen electrode inlet line or the pressure adjusting mechanism via a circulating gas suction mechanism;
Cooling the hydrogen electrode outlet gas that does not circulate as this circulating gas through a cooler to separate excess water to produce hydrogen; and
A method for producing hydrogen, comprising:

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