WO2018142615A1

WO2018142615A1 - Electrochemical system and chromium recovery method for electrochemical system

Info

Publication number: WO2018142615A1
Application number: PCT/JP2017/004231
Authority: WO
Inventors: 健太郎松永; 亀田　常治; 吉野　正人; 憲和長田
Original assignee: 株式会社東芝
Priority date: 2017-02-06
Filing date: 2017-02-06
Publication date: 2018-08-09
Also published as: JP6833876B2; JPWO2018142615A1

Abstract

An electrochemical system according to an embodiment has at least one electrochemical cell, a supply line, a heating part, and a chromium recovery unit. The electrochemical cell has an electrolyte layer of a solid oxide, and an oxygen electrode and a hydrogen electrode which are respectively disposed on both sides of the electrolyte layer. The supply line has at least a portion composed of a metal which includes chromium, and supplies a gas to the oxygen electrode of the at least one electrochemical cell. The heating part is disposed on the supply line and heats the gas. The chromium recovery unit is disposed between the heating part on the supply line and the electrochemical cell, and recovers chromium oxides from the gas.

Description

Electrochemical system and chromium recovery method for electrochemical system

Embodiments of the present invention relate to an electrochemical system and a chromium recovery method of the electrochemical system.

A solid oxide type electrochemical cell uses a solid oxide having oxygen ion conductivity at a relatively high temperature (eg, 600 to 1000 ° C.) as an electrolyte, and is a fuel cell (solid electrolyte fuel cell: SOFC) or an electrolytic cell. It operates as (solid oxide electrolytic cell: SOEC). The SOFC reacts a reducing agent (such as hydrogen or hydrocarbon) with an oxidizing agent (such as oxygen) through an electrolyte, and extracts the reaction energy as electricity. SOEC electrolyzes high-temperature water vapor to obtain hydrogen and oxygen.

When the electrochemical cell is operated for a long period, its characteristics are preferably stable over time. One of the causes of the deterioration of characteristics over time is chromium poisoning of the oxygen electrode. Chromium is generally contained in metal constituent materials such as gas pipes and separators, and becomes an oxide at high temperatures. The chromium oxide is separated from the metal constituent material, contacts the oxygen electrode, reacts with the constituent material, and is deposited on the oxygen electrode. This deposit may inhibit the reaction at the oxygen electrode.

Japanese Patent No. 5959635 Japanese Patent No. 5266930 Japanese Patent No. 559995

The problem to be solved by the present invention is to provide an electrochemical system and a method for recovering chromium of the electrochemical system, in which characteristic deterioration 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 a solid oxide electrolyte layer and an oxygen electrode and a hydrogen electrode arranged on both sides thereof. The supply line is made of a metal containing at least part of chromium, and supplies gas to the oxygen electrode of the at least one electrochemical cell. The heating unit is disposed on the supply line and heats the gas. The chromium recovery unit is disposed between the heating unit on the supply line and the electrochemical cell, and recovers chromium oxide in the gas.

According to the present invention, it is possible to reduce characteristic deterioration caused by chromium.

FIG. 1 is a block diagram showing a solid oxide electrochemical system according to the first embodiment. 1 is a schematic diagram illustrating a configuration of an electrochemical cell stack 10. FIG. 4 is a plan view showing details of a cell unit 11 of the electrochemical cell stack 10. FIG. 2 is an exploded cross-sectional view showing details of a cell unit 11 of an electrochemical cell stack 10. FIG. 2 is a cross-sectional view schematically illustrating an example of a chromium recovery unit 20. FIG. It is a perspective view showing typically an example of chromium recovery unit 20a. It is a block diagram showing the solid oxide type electrochemical system which concerns on 2nd Embodiment.

(First embodiment)
FIG. 1 is a block diagram showing a solid oxide electrochemical system according to the first embodiment.
The solid oxide electrochemical system includes an electrochemical cell stack 10, a chromium recovery unit 20,

heat exchangers

30a and 30b, and an external power source 40.

FIG. 2 is a schematic diagram 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. 3A shows a state in which a separator 16b, an insulating sheet 17, and a current collector 18b described later are excluded from the cell unit 11. FIG.

The solid oxide electrochemical system performs power generation or electrolysis using the hydrogen electrode gas G10 and the oxygen electrode gas G20, and discharges the hydrogen electrode waste gas G11 and the oxygen electrode waste gas G21. The cell unit 11 has a through hole H through which these gases pass. 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.

During power generation, a reducing gas (such as hydrogen or hydrocarbon) and an oxidizing gas (such as oxygen) are used as the hydrogen electrode gas G10 and the oxygen electrode gas G20. At this time, the hydrogen electrode waste gas G11 contains unreacted reducing gas and water vapor generated by the power generation reaction. The oxygen electrode waste gas G21 contains an unreacted oxidizing gas.

During electrolysis, water vapor is used as 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 necessary. The hydrogen electrode waste gas G11 includes unreacted water vapor and hydrogen gas generated by electrolysis. The oxygen electrode 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., as will be described later, the hydrogen electrode gas G10 and the oxygen electrode gas G20 are heated by a heating mechanism (

heat exchangers

30a, 30b, etc.). Then, it is supplied to the electrochemical cell stack 10. Therefore, members such as a supply line (piping) and a heating mechanism for the high-temperature hydrogen electrode gas G10 and the oxygen electrode gas G20 are made of a metal material (metal containing chromium, for example, stainless steel) having excellent oxidation resistance at high temperatures. It is customary to form. A chromium oxide layer having a certain thickness is formed on the surface of the member, and further oxidation (corrosion) is prevented.
In addition, the heating mechanism of the hydrogen electrode gas G10 is not shown for easy understanding.

The electrochemical cell stack 10 includes a cell unit 11,

bus bars

12a and 12b, and

end plates

13a and 13b. A plurality of cell units 11 are stacked, and

bus bars

12a and 12b and

end plates

13a and 13b are arranged above and below them.

The cell unit 11 includes a solid oxide 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 the plurality of solid oxide electrochemical cells 15 during power generation and supplying current during electrolysis.

End plates

13 a and 13 b

fix bus bars

12 a and 12 b above and below a plurality of solid oxide electrochemical cells 15. As a result, electrical connection and gas sealing in the entire electrochemical cell stack 10 are ensured.

The solid oxide electrochemical cell 15 is a unit cell that functions as an SOFC or SOEC, and a plurality of the solid oxide electrochemical cells 15 are used in order to increase the output. The solid oxide electrochemical cell 15 includes a hydrogen electrode 151, an electrolyte layer 152, and an oxygen electrode 153. An oxygen electrode 153 and a hydrogen electrode 151 are disposed on both sides of the solid oxide electrolyte layer 152.
Electricity is generated by supplying a reducing gas and an oxidizing gas to the hydrogen electrode 151 and the oxygen electrode 153 of the solid oxide electrochemical cell 15, respectively. Alternatively, water vapor is supplied to the hydrogen electrode 151 for electrolysis.

The hydrogen electrode 151 includes particles of a hydrogen electrode catalytic metal and oxygen ion conductive oxide particles. As a hydrogen electrode catalyst metal, metal oxides, such as metals, such as nickel, silver, or platinum, nickel oxide, or cobalt oxide, are mentioned, for example. The oxygen ion conductive oxide is a ceramic, for example, a ceria-based oxide such as samaria-stabilized ceria (SDC) or gadolinia-stabilized ceria (GDC), or a zirconia-based oxide such as yttria-stabilized zirconia (YSZ). Can be mentioned. As the oxygen ion conductive oxide, a solid oxide of the electrolyte layer 152 described later may be used.

The electrolyte layer 152 is a solid oxide layer having electronic insulation and oxygen ion conductivity. Examples of the solid oxide include stabilized zirconia, perovskite oxide, and ceria (CeO ₂ ) -based electrolyte solid solution.
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 oxide include LaSrGaMg oxide, LaSrGaMgCo oxide, and LaSrGaMgCoFe oxide. As the ceria-based electrolyte solid solution, a solid solution in which Sm ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , or the like is dissolved in a material containing CeO ₂ can be given.

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

The oxygen electrode 153 is made of a material that can efficiently dissociate oxygen and has electron conductivity. Examples of the material include lanthanum, strontium, manganese (LaSrMn) -based perovskite oxide (LSM), LaSrCo oxide (LSC), LaSrCoFe oxide (LSCF), LaSrFe oxide (LSF), LaSrMnCo oxide (LSMCoCo oxide). ), 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 An oxide (BSFC), a YSrFeCo oxide (YLFC), a YCuCoFe oxide (YCCF), or a YBaCu oxide (YBC) can be used.
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, or the like. Furthermore, components such as Pt, Ru, Au, Ag, and Pd may be added to the oxygen electrode 153, for example.

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

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

The hydrogen electrode gas G10 and the hydrogen electrode exhaust gas G11 flow into and out of the groove 162 from the pair of upper and lower through holes H in FIG. 3A. The hydrogen electrode gas G <b> 10 is supplied from one of these through holes H to the hydrogen electrode 151 through the groove 162. The reacted hydrogen electrode gas (hydrogen electrode exhaust gas) G11 passes through the groove 162 and is discharged from the other through hole H.

The oxygen electrode gas G20 and the oxygen electrode exhaust gas G21 flow into and out of the groove 163 from the pair of left and right through holes H in FIG. 3A. The oxygen electrode gas G <b> 20 is supplied from one of these through holes H to the oxygen electrode 153 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.

Current collectors

18a and 18b electrically connect hydrogen electrode 151 and oxygen electrode 153 to corresponding separators 16a and 16b, respectively.

As described above, members such as a gas supply line (piping) and a heating mechanism are formed of a metal containing chromium, and are protected from corrosion at high temperatures by the chromium oxide layer.
However, this oxide may leave the member and move by the oxygen electrode gas G20. That is, a part of the chromium oxide is sublimated (in a gaseous state) or broken into a fine powder and scattered (in a solid state). Thus, there is a possibility that the chromium oxide released from the member reaches the oxygen electrode 153, reacts and precipitates, and inhibits the reaction at the oxygen electrode 153.

FIG. 4 is a cross-sectional view schematically illustrating an example of the chromium recovery unit 20.
The chromium recovery unit 20 is disposed 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 includes 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 blocks the inside from the outside.
The gas supply port 22 and the gas discharge port 23 are gas outlets for supplying and discharging the oxygen electrode gas G <b> 20 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 in the outer shell 21 (the area of the absorption layer 26). 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 partitions. 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.

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

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

At this time, the vapor pressure P1 of the oxide C1 is equal to or lower than the vapor pressure P2 of the compound C2 formed by the reaction of the chromium oxide in the oxidizing electrode gas G10 with the oxygen electrode 153 (P1 ≦ P2). If the vapor pressure is 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 accumulated in the absorption layer 26 finally, but is accumulated in the oxygen electrode 153 of the electrochemical cell stack 10.

The magnitude relationship between the vapor pressures may be the result of comparing the vapor pressure at the same temperature with the generated oxide C1 and the compound C2 being different, or the generated oxide C1 and the compound C2 being the same, You may achieve by making the temperature of the absorption layer 26 lower than the oxygen electrode 153.

As the substance M, the following materials (1) and (2) can be used.
(1) Metal or metal oxide containing manganese As the substance M, for example, manganese alone, manganese chromium steel, ferromanganese manganese iron ferrite, or the like can be used.
(2) Oxide Material Used for Oxygen Electrode 153 Substance 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.
Among these, materials containing Mn, LSM, LSMCo, LSMCr, LCM, GSM, PCaM, and PSM are preferable, and LSM is particularly preferable. Chromium precipitation can be accelerated | stimulated because manganese contained in the substance M reacts 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, the necessity of applying a temperature difference (for example, 50 to 100 ° C.) to the chromium recovery unit 20 (oxygen electrode 153) and the electrochemical cell stack 10 (absorption layer 26) increases. 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 probability of contact with chromium oxide (vapor or fine powder) in the oxygen electrode gas G20. For example, the porous absorption layer 26 can be formed by applying or molding an oxide material powder.

The electrode 27 is a conductor disposed on the absorption layer 26, and applies a negative potential from the external power supply 40 to the absorption layer 26. By making the absorption layer 26 have a negative potential, absorption of chromium can be promoted. The electrode 27 has air permeability (for example, a mesh shape or a porous shape) 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 20 a includes a base 28, an insulating layer 25, an absorption layer 26, and an electrode 27. The base 28 is made of a material having conductivity and heat resistance (for example, a metal such as stainless steel) and has a plurality of through holes 29. An insulating layer 25, an absorption layer 26, and an electrode 27 are stacked 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 of the chromium recovery unit 20, detailed description thereof is 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 the gas G20 to the chromium recovery unit 20, and is disposed 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. The temperature of the absorption layer 26 is lowered to some extent (for example, by making it lower than the operating temperature of the oxygen electrode 153, it becomes possible to effectively recover chromium. On the other hand, if the temperature is too high, the chromium that has reacted once detaches and the absorption of chromium does not proceed.

By providing a certain temperature difference between the chromium recovery unit 20 (absorption layer 26) and the electrochemical cell stack 10 (oxygen electrode 153), efficient recovery of chromium in the chromium recovery unit 20 and in the electrochemical cell stack 10 are achieved. It is 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 electrochemical cell 15). That is, the temperature of a part of the absorption layer 26 is allowed to be equal to or higher than the temperature of the oxygen electrode 153.

The heat exchanger 30 b heats the gas G <b> 20 exhausted from the chromium recovery unit 20 and supplies it to the electrochemical cell stack 10. The heat exchanger 30b is disposed between the chromium recovery unit 20 and the electrochemical cell 10 on the gas G20 supply line, and functions as a second heating unit that heats the gas G20. By using the heat exchanger 30b, it becomes easier to provide an appropriate temperature difference between the chromium recovery unit 20 and the electrochemical cell stack 10.
In addition, when this temperature difference does not matter so much, the heat exchanger 30b may be omitted.

In the above, the

heat exchangers

30a and 30b are heating the gas G20 using the exhaust gas G21. The gas G20 may be heated using the gas G11 instead of the exhaust gas G21 or together with the exhaust gas G21. Alternatively, one or both of the

heat exchangers

30a and 30b may be replaced with a heater to heat the gas G20 with electricity.

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

In this embodiment, the chromium recovery unit 20 absorbs 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 operation can be efficiently performed over a long period.

(Second Embodiment)
FIG. 6 is a block diagram showing a solid oxide electrochemical system according to the second embodiment.
The same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
The solid oxide 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 20 a has a configuration corresponding to the electrochemical cell stack 10. That is, the chromium recovery unit 20a includes a cell unit 11,

bus bars

12a and 12b, and

end plates

13a and 13b. The cell unit 11 includes a solid oxide electrochemical cell (single cell) 15a, separators 16a and 16b, an insulating sheet 17, and

current collectors

18a and 18b. The solid oxide electrochemical cell 15a includes 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, such as 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.
Among these, materials containing Mn, LSM, LSMCo, LSMCr, LCM, GSM, PCaM, and PSM are preferable, and LSM is particularly preferable. When manganese reacts with Cr, absorption of chromium can be promoted.

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

Here, the electrochemical cell stack used as the chromium recovery unit 20a is preferably operated as a fuel cell. Adsorption of chromium in the gas G20 to the oxygen electrode 153a can be promoted by the voltage accompanying the power generation.
For this reason, reducing gas (gas G10) is supplied to the hydrogen electrode 151a of the chromium recovery unit 20a. As a result, combined with the supply of the oxidizing gas (gas G20) to the oxygen electrode 153a, the chromium recovery unit 20a generates power.

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

As in 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 providing a certain temperature difference between the chromium recovery unit 20 (oxygen electrode 153a) and the electrochemical cell stack 10 (oxygen electrode 153), efficient recovery of chromium in the chromium recovery unit 20 and in the electrochemical cell stack 10 are achieved. It is 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 make an appropriate temperature difference between the chromium recovery unit 20a and the electrochemical cell stack 10.
In addition, when 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 efficiently operated.

According to this embodiment, the chromium recovery unit 20a absorbs 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 operation can be efficiently performed over a long period.

Although several 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 forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims

At least one electrochemical cell having a solid oxide electrolyte layer and an oxygen electrode and a hydrogen electrode respectively disposed on both sides thereof;
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 disposed on the supply line for heating the gas;
A chromium recovery unit disposed between the heating unit on the supply line and the electrochemical cell, and recovering chromium oxide in the gas;
An electrochemical system comprising:
The chromium recovery unit is
A member having a predetermined surface;
An oxide having a vapor pressure equal to or lower than that of the compound formed on the predetermined surface and reacting with the chromium oxide in the gas to react with the oxygen electrode and the chromium oxide. The electrochemical system of claim 1, comprising:
An electrode disposed on the layer of material;
A power source for applying a voltage to the electrode;
The electrochemical system according to claim 2, further comprising:
The electrochemical system according to claim 2, wherein a temperature of the predetermined surface is lower than an operating temperature of the electrochemical cell.
The chromium recovery unit is
A second electrolyte layer of solid oxide, and at least one second electrochemical cell having a second oxygen electrode and a second hydrogen electrode respectively disposed on both sides thereof,
The second oxygen electrode absorbs chromium oxide in the gas;
The electrochemical system according to claim 1.
The second electrochemical cell is an electrochemical cell whose characteristics as a fuel cell or an electrolysis cell are lower than those of the electrochemical cell.
The electrochemical system according to claim 5.
At least one electrochemical cell having a solid oxide electrolyte layer and an oxygen electrode and a hydrogen electrode respectively disposed on both sides thereof;
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 chromium recovery method for an electrochemical system, which is disposed on the supply line and includes a heating unit that heats the gas.
The chromium recovery method of the electrochemical system which collect | recovers the chromium oxide in the said gas between the said heating part on the said supply line, and the said electrochemical cell.