JP6833876B2 - Electrochemical system and chromium recovery method for electrochemical system - Google Patents

Description

Embodiments of the present invention relate to electrochemical systems and methods of recovering chromium in electrochemical systems.

The solid oxide fuel cell uses a solid oxide having oxygen ion conductivity at a relatively high temperature (for example, 600 to 1000 ° C.) as an electrolyte, and uses a fuel cell (solid electrolyte fuel cell: SOFC) or an electrolytic cell. Operates as (Solid Oxide Electrolyte Cell: SOEC). SOFC reacts a reducing agent (hydrocarbon, hydrocarbon, etc.) with an oxidizing agent (oxygen, etc.) via an electrolyte, and extracts the reaction energy as electricity. SOEC electrolyzes hot steam to obtain hydrogen and oxygen.

When the electrochemical cell is operated for a long period of time, it is preferable that its characteristics are stable over time. Chromium poisoning of the oxygen electrode is one of the factors that cause the properties to deteriorate over time. Chromium is generally contained in metal constituent materials such as gas pipes and separators, and becomes an oxide at high temperatures. This chromium oxide separates from the metal constituent material and comes into contact with the oxygen electrode, reacts with the constituent material, and precipitates at the oxygen electrode. This precipitate may inhibit the reaction at the oxygen electrode.

Japanese Patent No. 5959635 Japanese Patent No. 5266930 Japanese Patent No. 5599956

An object to be solved by the present invention is to provide an electrochemical system and a method for recovering chromium in an electrochemical system in which deterioration of characteristics caused by chromium is reduced.

The electrochemical system according to the embodiment includes at least one electrochemical cell, a supply line, a heating unit, and a chromium recovery unit. The electrochemical cell has an electrolyte layer of a solid oxide and an oxygen electrode and a hydrogen electrode arranged on both sides thereof, respectively. The supply line is composed of at least a part of a metal containing chromium and supplies gas to the oxygen electrode of the at least one electrochemical cell. The heating unit is arranged on the supply line to heat the gas. The chromium recovery unit is arranged between the heating unit and the electrochemical cell on the supply line to recover the chromium oxide in the gas. The chromium recovery unit is arranged on the predetermined surface with a member having a predetermined surface, reacts with the chromium oxide in the gas, and is formed by reacting the oxygen electrode with the chromium oxide. It includes a layer of a material that forms an oxide having a vapor pressure equal to or less than that of a compound, an electrode arranged on the layer of the material, and a power source that applies a voltage to the electrode .

According to the present invention, it is possible to reduce the deterioration of characteristics caused by chrome.

FIG. 1 is a block diagram showing a solid oxide-type electrochemical system according to the first embodiment. It is a schematic diagram which shows the structure of an electrochemical cell stack 10. It is a top view which shows the detail of the cell unit 11 of the electrochemical cell stack 10. It is an exploded sectional view which shows the detail of the cell unit 11 of the electrochemical cell stack 10. It is sectional drawing which shows an example of the chromium recovery unit 20 schematically. It is a perspective view which shows an example of the chromium recovery unit 20a schematically. It is a block diagram which shows the solid oxide type electrochemical system which concerns on 2nd Embodiment.

(First Embodiment)
FIG. 1 is a block diagram showing a solid oxide-type electrochemical system according to the first embodiment.
The solid oxide fuel cell electrochemical system has an electrochemical cell stack 10, a chromium recovery unit 20, heat exchangers 30a and 30b, and an external power supply 40.

FIG. 2 is a schematic view showing the configuration of the electrochemical cell stack 10. 3A and 3B are a plan view and an exploded sectional view showing details of the cell unit 11 of the electrochemical cell stack 10, respectively. Note that FIG. 3A shows a state in which the separator 16b, the insulating sheet 17, and the current collector 18b, which will be described later, are excluded from the cell unit 11.

The solid oxide type electrochemical system uses hydrogen polar gas G10 and oxygen polar gas G20 to generate electricity or electrolyze, and discharges hydrogen polar waste gas G11 and oxygen polar waste gas G21. The cell unit 11 has a through hole H for passing these gases. Further, a hydrogen electrode gas supply line and an oxygen electrode gas supply line (pipe) are used to supply the hydrogen electrode gas G10 and the oxygen electrode gas G20 to the electrochemical cell stack 10, respectively.

At the time of power generation, a reducing gas (hydrogen, hydrocarbon, etc.) and an oxidizing gas (oxygen, etc.) are used for the hydrogen polar gas G10 and the oxygen polar gas G20. At this time, the hydrogen waste gas G11 contains an unreacted reducing gas and water vapor generated by the power generation reaction. The oxygen waste gas G21 contains an unreacted oxidizing gas.

At the time of electrolysis, water vapor is used for the hydrogen electrode gas G10. At this time, it is not always necessary to supply the oxygen electrode gas G20, but various gases (for example, air and oxygen) are supplied as the oxygen electrode gas G20 as needed. The hydrogen waste gas G11 contains unreacted water vapor and hydrogen gas produced by electrolysis. Oxygen waste gas G21 contains oxygen gas generated by electrolysis.

Since the electrochemical cell stack 10 normally operates at a high temperature of about 600 to 1000 ° C., the hydrogen electrode gas G10 and the oxygen electrode gas G20 are heated by a heating mechanism (heat exchangers 30a, 30b, etc.) as described later. After that, it is supplied to the electrochemical cell stack 10. Therefore, members such as the supply line (piping) of the high-temperature hydrogen electrode gas G10 and the oxygen electrode gas G20 and the heating mechanism are made of a metal material (metal containing chromium, for example, stainless steel) having excellent oxidation resistance at high temperature. It is usually formed. A chromium oxide layer having a constant thickness is formed on the surface of the member to prevent further oxidation (corrosion).
For the sake of clarity, the heating mechanism of the hydrogen electrode gas G10 is not shown.

The electrochemical cell stack 10 has a cell unit 11, bus bars 12a and 12b, and end plates 13a and 13b. A plurality of cell units 11 are laminated, and bus bars 12a and 12b and end plates 13a and 13b are arranged above and below the cell units 11.

The cell unit 11 has a solid oxide-type electrochemical cell (single cell) 15, separators 16a and 16b, an insulating sheet 17, and current collectors 18a and 18b, and performs power generation and electrolysis.

The bus bars 12a and 12b are conductive terminals for extracting electric power from a plurality of solid oxide-type electrochemical cells 15 at the time of power generation and supplying an electric current at the time of electrolysis.
The end plates 13a and 13b fix the bus bars 12a and 12b above and below the plurality of solid oxide-type electrochemical cells 15. As a result, an electrical connection and a gas seal are ensured throughout the electrochemical cell stack 10.

The solid oxide-type electrochemical cell 15 is a unit cell that functions as SOFC or SOEC, and a plurality of solid oxide-type electrochemical cells 15 are stacked and used for high output. The solid oxide-type electrochemical cell 15 has a hydrogen electrode 151, an electrolyte layer 152, and an oxygen electrode 153. An oxygen electrode 153 and a hydrogen electrode 151 are arranged on both sides of the solid oxide electrolyte layer 152, respectively.
Electricity is generated by supplying a reducing gas and an oxidizing gas to the hydrogen pole 151 and the oxygen pole 153 of the solid oxide-type electrochemical cell 15, respectively. Alternatively, steam is supplied to the hydrogen electrode 151 for electrolysis.

The hydrogen electrode 151 includes particles of a hydrogen electrode catalyst metal and particles of an oxygen ion conductive oxide. Examples of the hydrogen electrode catalyst metal include metals such as nickel, silver, and platinum, and metal oxides such as nickel oxide and cobalt oxide. Oxygen ion conductive oxides include ceramics, such as ceria-based oxides such as Samaria-stabilized ceria (SDC) or gadlinear-stabilized ceria (GDC), or zirconia-based oxides such as yttria-stabilized zirconia (YSZ). Can be mentioned. As the oxygen ion conductive oxide, the solid oxide of the electrolyte layer 152 described later may be used.

The electrolyte layer 152 is a layer of a solid oxide having electron insulation and oxygen ion conductivity. Examples of this solid oxide include stabilized zirconia, perovskite-type oxides, and _{solid solutions of ceria (CeO 2} ) -based electrolytes.
Stabilized zirconia is zirconia in which a stabilizer is dissolved in zirconia. As the stabilizer, for _{example, Y 2 O 3, Sc 2} O 3, Yb 2 O 3, Gd 2 O 3, Nd 2 O 3, CaO, MgO or the like can be mentioned. Examples of the perovskite-type oxide include LaSrGaMg oxide, LaSrGaMgCo oxide, and LaSrGaMgCoFe oxide. Examples of the ceria-based electrolyte solid solution include a solid solution obtained by dissolving _{Sm 2} O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , or La ₂ O ₃ in a material containing _{CeO 2.}

The electrolyte layer 152 has, for example, electron insulation and oxygen ion conductivity in the temperature range of 600 to 1000 ° C. Within this temperature range, oxygen ions can pass through the electrolyte layer 152.

The oxygen electrode 153 is made of a material capable of efficiently dissociating oxygen and having electron conductivity. Examples of this material include lanthanum strontium manganese (LaSrMn) -based perovskite oxide (LSM), LaSrCo oxide (LSC), LaSrCoFe oxide (LSCF), LaSrFe oxide (LSF), and LaSrMnCo oxide (LSMCo). ), LaSrMnCr Oxide (LSMCr), LaComn Oxide (LCM), LaSrCu Oxide (LSC), LaSrFeNi Oxide (LSFN), LaNiFe Oxide (LNF), LaBaCo Oxide (LBC), LaNiCo Oxide (LNC) , LaSrAlFe Oxide (LSAF), LaSrCoNiCu Oxide (LSCNC), LaSrFeNiCu Oxide (LSFNC), LaNi Oxide (LN), GdSrCo Oxide (GSC), GdSrMn Oxide (GSM), PrCaMn Oxide (PCaM), PrSrMn Oxide (PSM), PrBaCo Oxide (PBC), SmSrCo Oxide (SSC), NdSmCo Oxide (NSC), BiSrCaCu Oxide (BSCC), BaLaFeCo Oxide (BLFC), BaSrFeCo Oxide (BSFC), YSrFeCo Oxides (YLFC), YCuCoFe oxides (YCCF), or YBaCu oxides (YBC) can be mentioned.
The oxygen electrode 153 may be a mixture of these oxides. For example, it may be formed of LSM-YSZ, LSCF-SDC, LSCF-GDC, LSCF-YDC, LSCF-LDC, LSCF-CDC, LSM-ScSZ, LSM-SDC, LSM-GDC and the like. Further, components such as Pt, Ru, Au, Ag, and Pd may be added to the oxygen electrode 153.

The separators 16a and 16b are for blocking the solid oxide-type electrochemical cell 15 from the outside world, and are made of a metal having conductivity and heat resistance (for example, stainless steel).

The separator 16a has a recess 161, a groove 162, and a through hole H.
The solid oxide-type electrochemical cell 15 is housed in the recess 161. A plurality of grooves 162 are arranged in the recess 161 and the hydrogen electrode gas G10 flows in the vertical direction of FIG. 3A.
The separator 16b has a groove 163. A plurality of grooves 163 are arranged, and the oxygen electrode gas G20 flows in the left-right direction of FIG. 3A.

The hydrogen electrode gas G10 and the hydrogen electrode exhaust gas G11 flow in and out of the groove 162 from the pair of upper and lower through holes H in FIG. 3A. The hydrogen electrode gas G10 is supplied to the hydrogen electrode 151 from one of these through holes H through the groove 162. The reacted hydrogen electrode gas (hydrogen electrode exhaust gas) G11 is discharged from the other through hole H through the groove 162.

The oxygen electrode gas G20 and the oxygen electrode exhaust gas G21 flow in and out of the groove 163 from the pair of left and right through holes H in FIG. 3A. The oxygen electrode gas G20 is supplied to the oxygen electrode 153 from one of these through holes H through the groove 163. The reacted oxygen electrode gas (oxygen electrode exhaust gas) G21 is discharged from the other through hole H through the groove 163.

The insulating sheet 17 electrically insulates between the separators 16a and 16b.
The current collectors 18a and 18b electrically connect the hydrogen poles 151 and the oxygen poles 153 to the corresponding separators 16a and 16b, respectively.

As described above, members such as gas supply lines (piping) and heating mechanisms are made of a metal containing chromium, and are protected from corrosion at high temperatures by a chromium oxide layer.
However, this oxide may separate from the member and be moved by the oxygen pole gas G20. That is, a part of the chromium oxide sublimates (gas state) or breaks into fine powder and scatters (solid state). In this way, the chromium oxide released from the member may reach the oxygen electrode 153, react and precipitate, and inhibit the reaction at the oxygen electrode 153.

FIG. 4 is a cross-sectional view schematically showing an example of the chromium recovery unit 20.
The chromium recovery unit 20 is arranged between the heat exchanger 30a (heating unit) and the electrochemical cell stack 10, and recovers and fixes the chromium oxide in the oxygen electrode gas G20.
The chromium recovery unit 20 has an outer shell 21, a gas supply port 22, a gas discharge port 23, a partition wall 24, an insulating layer 25, an absorption layer 26, and an electrode 27.

The outer shell 21 and the partition wall 24 can be made of a material having conductivity and heat resistance (for example, metal).
The outer shell 21 shields the inside from the outside world.
The gas supply port 22 and the gas discharge port 23 are gas inlets and outlets for supplying and discharging the oxygen electrode gas G20 into the outer shell 21.
The partition wall 24 divides the inside of the outer shell 21 into a plurality of sections to increase the surface area (area of the absorption layer 26) inside the outer shell 21. The partition wall 24 corresponds to a member having a predetermined surface.
The partition wall 24 has a flow path 241 (for example, a through hole) for connecting adjacent compartments. As a result, the oxidizing gas supplied from the gas supply port 22 into the outer shell 21 passes through the plurality of compartments and is discharged from the gas discharge port 23.

An insulating layer 25, an absorbing layer 26, and an electrode 27 are formed on the surface of the partition wall 24. The insulating layer 25, the absorbing layer 26, and the electrode 27 can also be formed inside the outer shell 21.
The insulating layer 25 electrically insulates between the absorbing layer 26 and the partition wall 24 (and the outer shell 21). As will be described later, by keeping the absorption layer 26 at a negative potential, the absorption of chromium can be promoted.

The absorption layer 26 is a layer of the substance M that reacts with the chromium oxide in the oxide electrode gas G10 to produce the oxide C1. Chromium in the oxidizing gas reacts with the substance M in the absorption layer 26 to generate a stable oxide C1, so that chromium is adsorbed and fixed.

At this time, the vapor pressure P1 of the oxide C1 is equal to or less than the vapor pressure P2 of the compound C2 formed by the reaction of the chromium oxide in the oxide electrode gas G10 with the oxygen electrode 153 (P1 ≦ P2). If the vapor pressure has such a relationship, the chromium oxide in the gas G10 is accumulated in the absorption layer 26. If such a relationship is broken, the chromium oxide in the gas G10 is not finally accumulated in the absorption layer 26, but is accumulated in the oxygen electrode 153 of the electrochemical cell stack 10.

The magnitude relationship of this vapor pressure may be the result of comparing the vapor pressures at the same temperature because the produced oxides C1 and compound C2 are different, or the produced oxides C1 and compound C2 are the same and during operation. This may be achieved by lowering the temperature of the absorption layer 26 below the oxygen electrode 153.

The following materials (1) and (2) can be used as the substance M.
(1) As the manganese-containing metal or metal oxide substance M, for example, manganese alone, manganese chrome steel, ferromanganese manganese iron ferrite, or the like can be used.
(2) Oxide material used for oxygen electrode 153 Material M includes, for example, LSM, LSC, LSCF, LSF, LSMCo, LSMCr, LCM, LSC, LSFN, LNF, LBC, LNC, LSAF, LSCNC, LSFNC, LN , GSC, GSM, PCaM, PSM, PBC, SSC, NSC, BSCC, BLFC, BSFC, YLFC, YCCF, or YBC can be used.
Of these, materials containing Mn, LSM, LSMCo, LSMCr, LCM, GSM, PCaM, and PSM are preferable, and LSM is particularly preferable. Chromium precipitation can be promoted by reacting manganese contained in the substance M with Cr.

The constituent materials of the oxygen electrode 153 and the absorption layer 26 may be the same or different. In the case of the same material, as will be described later, there is an increasing need to provide a temperature difference (for example, 50 to 100 ° C.) between the chromium recovery unit 20 (oxygen electrode 153) and the electrochemical cell stack 10 (absorption layer 26). Even in the case of different materials, it is generally preferable that there is a certain temperature difference (for example, 50 to 100 ° C.).

The absorption layer 26 may be made porous to increase the contact probability with chromium oxide (vapor or fine powder) in the oxygen electrode gas G20. For example, a porous absorption layer 26 can be created by applying or molding a powder of an oxide material.

The electrode 27 is a conductor arranged on the absorption layer 26, and applies a negative potential from the external power source 40 to the absorption layer 26. By setting the absorption layer 26 to a negative potential, the absorption of chromium can be promoted. The electrode 27 is breathable (for example, mesh-like or porous) in order to bring the absorbing layer 26 into contact with the oxidizing gas.

FIG. 5 is a perspective view schematically showing another example of the chromium recovery unit 20a.
The chromium recovery unit 20a has a substrate 28, an insulating layer 25, an absorbing layer 26, and an electrode 27. The substrate 28 is made of a conductive and heat resistant material (eg, a metal such as stainless steel) and has a plurality of through holes 29. The insulating layer 25, the absorbing layer 26, and the electrode 27 are laminated in the through hole 29.
In the chromium recovery unit 20, the gas G20 meanders and flows, whereas in the chromium recovery unit 20a, the gas G20 flows linearly.

When the gas G20 passes through the through hole 29, the chromium in the gas G20 is absorbed by the absorption layer 26 and discharged to the outside.
Since the chromium absorption mechanism in the chromium recovery unit 20a is the same as that in the chromium recovery unit 20, detailed description thereof will be omitted.

The heat exchanger 30a heats the gas G20 using the high-temperature exhaust gas G21 discharged from the electrochemical cell stack 10 and supplies it to the chromium recovery unit 20, and is arranged on the supply line to heat the gas. Corresponds to the heating part.

At this time, the temperature of the heated gas G20 is set to be somewhat lower than the temperature in the electrochemical cell stack 10. By lowering the temperature of the absorption layer 26 to some extent (for example, lowering it below the operating temperature of the oxygen electrode 153, effective recovery of chromium is possible. Unless the temperature of the absorption layer 26 is raised to some extent, the reaction with chromium will occur. On the other hand, if the temperature is too high, the reacted chromium will be released once, and the absorption of chromium will not proceed.

By giving a certain temperature difference between the chromium recovery unit 20 (absorption layer 26) and the electrochemical cell stack 10 (oxygen electrode 153), efficient chromium recovery in the chromium recovery unit 20 and the electrochemical cell stack 10 can be performed. It becomes easy to achieve both efficient power generation (or electrolysis). This temperature difference is, for example, 50 to 100 ° C.

At this time, the average temperature of the absorption layer 26 (on the surface of the partition wall 24 and on the inner surface of the through hole 29) may be lower than the temperature of the oxygen electrode 153 (the operating temperature of the solid oxide-type electrochemical cell 15). That is, it is permissible that the temperature of a part of the absorption layer 26 is equal to or higher than the temperature of the oxygen electrode 153.

The heat exchanger 30b heats the gas G20 discharged from the chromium recovery unit 20 and supplies it to the electrochemical cell stack 10. The heat exchanger 30b is arranged between the chromium recovery unit 20 on the supply line of the gas G20 and the electrochemical cell 10, and functions as a second heating unit for heating the gas G20. By using the heat exchanger 30b, it becomes easier to give an appropriate temperature difference between the chromium recovery unit 20 and the electrochemical cell stack 10.
If this temperature difference is not a problem, the heat exchanger 30b may be omitted.

In the above, the heat exchangers 30a and 30b use the exhaust gas G21 to heat the gas G20. The gas G20 may be heated in place of the exhaust gas G21 or by using the gas G11 together with the exhaust gas G21. Further, one or both of the heat exchangers 30a and 30b may be replaced with heaters to electrically heat the gas G20.

The external power supply 40 applies a voltage between the electrode 27 of the chromium recovery unit 20 and the partition wall 24 (and the outer shell 21) to make the absorption layer 26 a negative potential. The absorption of chromium by the absorption layer 26 can be promoted.

In the present embodiment, the chromium recovery unit 20 absorbs the chromium oxide gas or fine powder generated from the piping of the oxygen electrode gas G20 and the surface of the heat exchanger 30a. As a result, deterioration of the characteristics of the electrochemical cell stack 10 can be suppressed, and efficient operation can be performed for a long period of time.

(Second Embodiment)
FIG. 6 is a block diagram showing a solid oxide-type electrochemical system according to the second embodiment.
The same configurations as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.
The solid oxide-type electrochemical system according to the second embodiment includes an electrochemical cell stack 10, a chromium recovery unit 20a, a heat exchanger 30a, a heater 50, and a controller 60.

The chromium recovery unit 20a has a configuration corresponding to the electrochemical cell stack 10. That is, the chromium recovery unit 20a has a cell unit 11, bus bars 12a and 12b, and end plates 13a and 13b. The cell unit 11 has a solid oxide-type electrochemical cell (single cell) 15a, separators 16a and 16b, an insulating sheet 17, and current collectors 18a and 18b. The solid oxide-type electrochemical cell 15a has a hydrogen electrode 151a, an electrolyte layer 152a, and an oxygen electrode 153a.

Chromium in the oxygen electrode gas G20 is adsorbed and fixed to the oxygen electrode 153a of the chromium recovery unit 20a.
The oxygen electrode 153a is an oxide material used for the oxygen electrode 153, for example, LSM, LSC, LSCF, LSF, LSMCo, LSMCr, LCM, LSC, LSFN, LNF, LBC, LNC, LSAF, LSCNC, LSFNC, LN, GSC. , GSM, PCaM, PSM, PBC, SSC, NSC, BSCC, BLFC, BSFC, YLFC, YCCF, or YBC can be used.
Of these, materials containing Mn, LSM, LSMCo, LSMCr, LCM, GSM, PCaM, and PSM are preferable, and LSM is particularly preferable. Manganese reacts with Cr to promote the absorption of chromium.

A used solid oxide-type electrochemical cell stack may be used for the chromium recovery unit 20a. That is, a solid oxide-type electrochemical cell stack having reduced SOFC or SOEC characteristics (due to factors other than chromium poisoning) can be used as the chromium recovery unit 20a.

Here, it is preferable that the electrochemical cell stack used as the chromium recovery unit 20a is operated as a fuel cell. The voltage associated with the power generation can promote the adsorption of chromium in the gas G20 to the oxygen electrode 153a.
Therefore, the reducing gas (gas G10) is supplied to the hydrogen electrode 151a of the chromium recovery unit 20a. As a result, the chromium recovery unit 20a generates electricity in combination with the supply of the oxidizing gas (gas G20) to the oxygen electrode 153a.

The controller 50 controls the overvoltage in the power generation reaction of the chromium recovery unit 20a. That is, the electric power generated by the chromium recovery unit 20a is appropriately supplied to or consumed in other places. By appropriately consuming the electric power generated by the chromium recovery unit 20a, the reaction in the chromium recovery unit 20a (oxygen electrode 153a), and eventually the absorption of chromium can be promoted. When the electric power generated by the chromium recovery unit 20a is stored in the chromium recovery unit 20a, the fuel cell reaction in the chromium recovery unit 20a is hindered.

Similar to the first embodiment, the heat exchanger 30a heats the gas G20 using the high temperature exhaust gas G21 discharged from the electrochemical cell stack 10 and supplies it to the chromium recovery unit 20. By giving a certain temperature difference between the chromium recovery unit 20 (oxygen pole 153a) and the electrochemical cell stack 10 (oxygen pole 153), efficient chromium recovery in the chromium recovery unit 20 and the electrochemical cell stack 10 can be performed. It becomes easy to achieve both efficient power generation (or electrolysis).

The heater 60 heats the gas G20 discharged from the chromium recovery unit 20a and supplies it to the electrochemical cell stack 10. By using the heater 60, it becomes easier to give an appropriate temperature difference between the chromium recovery unit 20a and the electrochemical cell stack 10.
If this temperature difference does not matter so much, the heater 60 may be omitted.
In the present embodiment, the electric power generated by the chromium recovery unit 20a is used for heating the gas G20 by the heater 60, and the system can be operated efficiently.

According to this embodiment, the chromium recovery unit 20a absorbs the chromium oxide gas or fine powder generated from the piping of the oxygen electrode gas G20 and the surface of the heat exchanger 30a. As a result, deterioration of the characteristics of the electrochemical cell stack 10 can be suppressed, and efficient operation can be performed for a long period of time.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

Claims (3)

An electrolyte layer of solid oxide and at least one electrochemical cell having oxygen and hydrogen poles located on either side of the electrolyte layer.
A supply line that is at least partially composed of a metal containing chromium and supplies gas to the oxygen electrode of the at least one electrochemical cell.
A heating unit arranged on the supply line and heating the gas,
A chromium recovery unit, which is arranged between the heating unit and the electrochemical cell on the supply line and recovers chromium oxide in the gas,
Equipped with
The chromium recovery unit
A member having a predetermined surface and
An oxide having a vapor pressure equal to or lower than that of a compound formed on the predetermined surface and reacting with the chromium oxide in the gas and reacting the oxygen electrode with the chromium oxide. With a layer of material that forms
Electrodes placed on the layer of material and
A power supply that applies voltage to the electrodes and
An electrochemical system equipped with. The temperature of the predetermined surface is electrochemical system of low claim 1 than the operating temperature of the electrochemical cell. An electrolyte layer of solid oxide and at least one electrochemical cell having oxygen and hydrogen poles located on either side of the electrolyte layer.
A supply line that is at least partially composed of a metal containing chromium and supplies gas to the oxygen electrode of the at least one electrochemical cell.
In a method for recovering chromium in an electrochemical system, which is arranged on the supply line and includes a heating unit for heating the gas.
Between the heating section and the electrochemical cell on the supply line,
A member having a predetermined surface and
An oxide having a vapor pressure equal to or lower than that of a compound formed on the predetermined surface and reacting with the chromium oxide in the gas and reacting the oxygen electrode with the chromium oxide. With a layer of material that forms
Electrodes placed on the layer of material and
A power supply that applies voltage to the electrodes and
By the chrome recovery unit equipped with
A method for recovering chromium in an electrochemical system for recovering chromium oxide in the gas.

Images