JP2008078334A - Thermoelectric device - Google Patents
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- JP2008078334A JP2008078334A JP2006255000A JP2006255000A JP2008078334A JP 2008078334 A JP2008078334 A JP 2008078334A JP 2006255000 A JP2006255000 A JP 2006255000A JP 2006255000 A JP2006255000 A JP 2006255000A JP 2008078334 A JP2008078334 A JP 2008078334A
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 119
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- 229910052712 strontium Inorganic materials 0.000 claims abstract description 25
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052788 barium Inorganic materials 0.000 claims abstract description 17
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- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims abstract description 9
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 6
- 239000010941 cobalt Substances 0.000 claims abstract description 6
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 6
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- -1 iron oxide compound Chemical class 0.000 claims description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 19
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 17
- 239000002737 fuel gas Substances 0.000 claims description 16
- 229930195733 hydrocarbon Natural products 0.000 claims description 13
- 150000002430 hydrocarbons Chemical class 0.000 claims description 13
- 239000001257 hydrogen Substances 0.000 claims description 12
- 229910052739 hydrogen Inorganic materials 0.000 claims description 12
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- 239000004215 Carbon black (E152) Substances 0.000 claims description 9
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- 230000007547 defect Effects 0.000 claims description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 claims description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 4
- 239000001569 carbon dioxide Substances 0.000 claims description 4
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 4
- 229910000428 cobalt oxide Inorganic materials 0.000 claims description 4
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- 238000009826 distribution Methods 0.000 claims description 4
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- 239000003792 electrolyte Substances 0.000 claims description 4
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- 229910000480 nickel oxide Inorganic materials 0.000 claims description 4
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 3
- 229910052772 Samarium Inorganic materials 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 3
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 claims description 3
- 239000003502 gasoline Substances 0.000 claims description 3
- 150000002431 hydrogen Chemical class 0.000 claims description 3
- 229910052746 lanthanum Inorganic materials 0.000 claims description 3
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 3
- 239000003345 natural gas Substances 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 3
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 3
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 claims description 3
- 229910052706 scandium Inorganic materials 0.000 claims description 3
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 claims description 3
- 229910052727 yttrium Inorganic materials 0.000 claims description 3
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims description 3
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims 1
- 239000002918 waste heat Substances 0.000 abstract description 13
- 150000002500 ions Chemical class 0.000 abstract description 9
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- 239000004020 conductor Substances 0.000 description 5
- 239000010416 ion conductor Substances 0.000 description 5
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 229910010293 ceramic material Inorganic materials 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
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- 229910052751 metal Inorganic materials 0.000 description 3
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
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- 229910001385 heavy metal Inorganic materials 0.000 description 2
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- 230000001590 oxidative effect Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910002909 Bi-Te Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
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- 230000005611 electricity Effects 0.000 description 1
- BDAGIHXWWSANSR-NJFSPNSNSA-N hydroxyformaldehyde Chemical compound O[14CH]=O BDAGIHXWWSANSR-NJFSPNSNSA-N 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
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- Fuel Cell (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
Description
本発明は、熱電材料、熱電変換素子、及び多層熱電変換システムに関するものであり、更に詳しくは、イオン伝導性及び熱電変換機能を有する酸化物材料、該材料を用いた電極としての利用と電極における化学反応場での直接的な廃熱回収を可能とする熱電変換素子、及び該素子を用いたガス流通構造に、高温燃料ガスを流通させ、素子上の加熱並びに発熱反応による温度差で熱電変換発電を可能にする多層熱電変換システムに関するものである。本発明は、高温ガス中の水素又は炭化水素種等の熱電変換素子上での酸素イオン伝導反応による燃料電池発電と、高温ガスからの電力の形成により、化学反応場での直接的かつ複合的な発電を行うことを可能とする熱電変換素子、及びそれを利用した熱電変換発電システムを提供するものである。 The present invention relates to a thermoelectric material, a thermoelectric conversion element, and a multilayer thermoelectric conversion system, and more specifically, an oxide material having ion conductivity and a thermoelectric conversion function, use as an electrode using the material, and an electrode. Thermoelectric conversion element that enables direct recovery of waste heat in a chemical reaction field, and high-temperature fuel gas in a gas distribution structure using the element, and thermoelectric conversion by temperature difference due to heating and exothermic reaction on the element The present invention relates to a multilayer thermoelectric conversion system that enables power generation. The present invention is directed to a direct and complex in a chemical reaction field by generating power from a fuel cell by an oxygen ion conduction reaction on a thermoelectric conversion element such as hydrogen or a hydrocarbon species in a high-temperature gas and forming power from the high-temperature gas. The present invention provides a thermoelectric conversion element that makes it possible to generate electric power and a thermoelectric conversion power generation system using the thermoelectric conversion element.
廃熱を利用する熱電発電技術は、燃焼を含めた化学反応にともなって拡散する熱エネルギーを、利用可能な電力として回収する技術として注目されている。更に、熱電発電は、材料固有の温度差による熱起電力（ゼーベック係数）を利用するシステムであり、タービンのような可動部が無いため、静かで故障がしにくい、といったメリットもある。例えば、２００ｔ／日のゴミ焼却炉では、燃焼廃熱として、６００−１１００℃の温度差が利用でき、廃熱としては、１０ＭＷものエネルギーが棄てられている。 Thermoelectric power generation technology that uses waste heat is attracting attention as a technology that recovers thermal energy that diffuses with chemical reactions including combustion as usable power. Furthermore, thermoelectric power generation is a system that uses a thermoelectromotive force (Seebeck coefficient) due to a temperature difference specific to a material, and has a merit that it is quiet and difficult to break down because there is no moving part such as a turbine. For example, in a 200 ton / day garbage incinerator, a temperature difference of 600-1100 ° C. can be used as combustion waste heat, and as much as 10 MW of energy is discarded as waste heat.
一方、生活に身近な自動車等でも、２００−７００℃の廃熱エネルギーが放出され、１０ｋＷほどのエネルギーが利用されずに棄てられている。これらの廃熱エネルギーを、１％でも熱電変換技術により回収できれば、エネルギーの有効利用、しいては二酸化炭素の排出削減といったエネルギー・環境において重要な技術となる。廃熱エネルギー回収技術での問題には、放出される熱エネルギーには波があり、また、徐々に、いろんな場所から放出されるため、エネルギー密度が小さく、回収するためには、多くの面積が必要となるといった問題もある。 On the other hand, waste heat energy of 200-700 ° C. is released even in automobiles familiar to daily life, and about 10 kW of energy is discarded without being used. If even 1% of these waste heat energy can be recovered by thermoelectric conversion technology, it will become an important technology in energy and environment, such as effective use of energy and reduction of carbon dioxide emissions. The problem with waste heat energy recovery technology is that there is a wave in the released heat energy, and since it is gradually released from various places, the energy density is low, and a large area is required for recovery. There is also a problem that it is necessary.
しかしながら、熱起電力の大きな熱電素子では、１℃の温度差であっても熱起電力は生じるため、それらを可能な限り回収し、電力へ変換すれば、小さな温度差や変動の大きな熱エネルギーにおいても、エネルギー回収の意義は大きい。更に、ポジティブな利用としては、化学反応をともなう反応器、例えば、燃料電池等では、反応量の増加にともない発熱量も増加するため、それらの反応場直下で熱電変換が可能となれば、密度の高い熱エネルギーが利用でき、熱拡散にともなうエネルギー放出といった回収の問題も少なくなる。 However, thermoelectric elements with a large thermoelectromotive force generate thermoelectromotive force even at a temperature difference of 1 ° C. Therefore, if they are recovered as much as possible and converted to electric power, thermal energy with a small temperature difference and large fluctuations is obtained. However, the significance of energy recovery is great. Furthermore, as a positive use, in a reactor with a chemical reaction, such as a fuel cell, the calorific value increases as the reaction amount increases, so if thermoelectric conversion is possible directly under the reaction field, the density is increased. High heat energy can be used, and the recovery problems such as energy release due to thermal diffusion are reduced.
一方、このような反応場直下で熱電変換によりエネルギーを回収する場合、材料の安定性といった他の問題の解決も必要となる。一般的に、熱電変換性能が高いＢｉ−Ｔｅ等の重金属の材料では、高温かつ酸化雰囲気では材料が酸化され、熱電変換特性も低下する。また、重金属を加熱することにより、重元素の拡散等の外部環境への影響も問題となる。一方、性能的には金属系材料より劣るが、熱安定性といった面からは、酸化雰囲気で安定な酸化物系の熱電変換材料も研究が進んでいる。特に、セラミック系の材料では、モジュール化により、１０００℃レベルの高温で数Ｗクラスの発電に成功した例もある。 On the other hand, when energy is recovered by thermoelectric conversion directly under such a reaction field, it is necessary to solve other problems such as material stability. In general, in a heavy metal material such as Bi-Te having high thermoelectric conversion performance, the material is oxidized at a high temperature in an oxidizing atmosphere, and the thermoelectric conversion characteristics are also deteriorated. In addition, when the heavy metal is heated, the influence on the external environment such as diffusion of heavy elements becomes a problem. On the other hand, although the performance is inferior to that of metal-based materials, research is also progressing on oxide-based thermoelectric conversion materials that are stable in an oxidizing atmosphere in terms of thermal stability. In particular, with ceramic materials, there have been examples of successful generation of several W classes at a high temperature of 1000 ° C. by modularization.
熱電発電を考える上で、従来の技術では、温度差の形成される雰囲気に熱電変換素子を配置して、熱移動にともなう温度差での熱電発電素子単独での発電の利用が主である（特許文献１）。一方、今後の燃料電池等の普及にともない、特に、多燃量利用及び総合エネルギー変換効率の高い固体酸化物電解質型燃料電池（ＳＯＦＣ）等の利用が進むと、システム運用の面から、発電にともなう熱の利用が重要となってくる。現在考えられるシステムでは、廃熱を利用し、温水を作り、暖房や冷房等へ展開することが考えられているが、電力需要と排出される熱エネルギーのバランスが、今後問題となってくる。 In consideration of thermoelectric power generation, in the conventional technology, thermoelectric conversion elements are arranged in an atmosphere where a temperature difference is formed, and the main use of the power generation by the thermoelectric power generation element alone at the temperature difference caused by heat transfer ( Patent Document 1). On the other hand, with the widespread use of fuel cells and the like in the future, especially when the use of solid oxide electrolyte fuel cells (SOFC) with high fuel consumption and high overall energy conversion efficiency is advanced, from the viewpoint of system operation, power generation Use of the accompanying heat becomes important. In the currently conceivable system, it is considered to use waste heat, create hot water, and deploy it to heating and cooling. However, the balance between power demand and discharged thermal energy will become a problem in the future.
特に、発電温度が８００−１０００℃近くの高い温度を利用するＳＯＦＣでは、熱エネルギーの有効利用が重要となってくる。これらの解決の一つの手段として、熱電素子による電力への変換とそのエネルギーの、バッテリー等への蓄電利用があるが、従来技術では、それを、発熱の大きなセルや配管付近へ熱電素子を配置し、電力変換を行うといった、単純なそれぞれの部品の組合せによって設計することが考えられる。 In particular, in an SOFC that uses a high power generation temperature close to 800-1000 ° C., effective use of thermal energy becomes important. One means of solving these problems is the conversion of electric power into thermoelectric elements and the storage of that energy in batteries, etc. In the prior art, thermoelectric elements are placed near cells or pipes that generate large amounts of heat. However, it is conceivable to design by simple combinations of parts such as power conversion.
しかしながら、エネルギー効率の高いＳＯＦＣといえども、電極中での燃料やイオン伝導の物質拡散にともなうエネルギーロスをともない、供給される燃料の化学エネルギーを十分に利用するには、いろいろな問題があって難しい。それらのエネルギーロスによる発熱は、発電を行うセル界面で最も高く、システムでの熱エネルギーからの直接的な電力エネルギーの回収において、最適なサイトは、セルもしくは電極界面である。 However, even with an energy efficient SOFC, there are various problems in fully utilizing the chemical energy of the supplied fuel, with the energy loss associated with the diffusion of fuel and ion-conducting materials in the electrode. difficult. Heat generation due to such energy loss is the highest at the cell interface where power is generated, and the optimal site for the recovery of electric power energy directly from the thermal energy in the system is the cell or electrode interface.
このようなエネルギーロスによる発熱をともなう化学反応場直下に、熱電変換素子を配置できれば、水素、炭化水素等の化学エネルギーからの燃料電池反応による電力エネルギーへの変換が向上することが期待できる（特許文献２）。そのために、従来の廃熱を利用する電力エネルギー回収技術の一つの手段である熱電変換材料が重要となる。更に、ＳＯＦＣは、大規模な発電システムだけではなく、家電、自動及び家庭用分散電源等の種々のマーケットに向けて研究も進んでおり、そのようなコンパクトでかつ高出力が必要とされる場合、単位あたりの燃料から多くのトータル電力エネルギーを得る新しい発電システムは重要な技術である。 If a thermoelectric conversion element can be placed directly under a chemical reaction field that generates heat due to such energy loss, it can be expected that conversion of chemical energy such as hydrogen and hydrocarbons into electric energy by fuel cell reaction will be improved (patent) Reference 2). For this purpose, a thermoelectric conversion material, which is one means of conventional power energy recovery technology using waste heat, is important. In addition, SOFC is being researched not only for large-scale power generation systems, but also for various markets such as home appliances, automatic and home-use distributed power supplies, etc. When such a compact and high output is required A new power generation system that obtains a lot of total energy from fuel per unit is an important technology.
燃料電池のようなセル反応場直下で熱エネルギーを回収する機能を付与する手段として、（１）従来の燃料電池電極に既存の熱電素子を貼付ける、もしくは、（２）燃料電池に利用可能な電極でかつ熱電起電力の大きな材料を利用する、等が考えられる。前者は、作製は容易であるが、燃料電池の電極と高温で利用可能な酸化物熱電素子では、熱膨張率の違い等により、十分な接合構造が形成できない問題があり、また、スペース的にも、燃料電池セルに比べて数倍もの熱電素子を配置することで容積が大きくなり、コンパクトなモジュール製造において問題となる。更に、セル界面での固体拡散等による燃料電池電極の活性低下等の問題も上げられる。 As a means for providing a function of recovering thermal energy directly under a cell reaction field such as a fuel cell, (1) pasting an existing thermoelectric element on a conventional fuel cell electrode, or (2) usable for a fuel cell It is conceivable to use an electrode and a material having a large thermoelectric power. The former is easy to manufacture, but there is a problem that a sufficient junction structure cannot be formed due to the difference in thermal expansion coefficient between the electrode of the fuel cell and the oxide thermoelectric element that can be used at a high temperature. However, the arrangement of thermoelectric elements several times as many as the fuel cells increases the volume, which is a problem in the production of compact modules. Furthermore, problems such as a decrease in the activity of the fuel cell electrode due to solid diffusion at the cell interface are raised.
一方、後者については、従来は検討されてはいないが、ＳＯＦＣ電極材料で重要となる酸素イオン伝導性が高い材料として、熱電変換酸化物材料のような電子伝導性に準ずるようなキャリア特性を持つ酸化物材料が研究されており、ＳＯＦＣの研究においては、注目されている。特に、低温でのＳＯＦＣ発電では、空気極での酸素のイオン化とその電極中の酸素イオンの伝導速度が重要であり、一般的には、低温ほどそれらが低下するため、発電電力が低くなるため、低温で酸素イオン伝導性が速い材料が要求されている。 On the other hand, although the latter has not been studied in the past, it has a carrier characteristic that conforms to the electron conductivity like a thermoelectric conversion oxide material as a material having high oxygen ion conductivity that is important for SOFC electrode materials. Oxide materials have been studied and are attracting attention in SOFC research. In particular, in SOFC power generation at low temperatures, the ionization of oxygen at the air electrode and the conduction speed of oxygen ions in the electrodes are important. Generally, the lower the temperature, the lower the generated power, and the lower the generated power. There is a demand for a material having a high oxygen ion conductivity at a low temperature.
一方、熱電酸化物材料では、電気的にはキャリア数が大きく、金属並みに電気が流れるが、キャリアの移動速度が遅く、そのために、温度差でのキャリア分布の偏りが大きくなり、熱起電力が高くなる材料が主なものである。従来の酸素イオン伝導体では、酸素イオン伝導性材料は、キャリア移動が結晶中の酸素イオン伝導のため、キャリアの移動速度が遅く、熱起電力は、数ｍＶオーダーで大きいが、熱電材料に比べると数桁電気伝導性が低い材料が多い。 On the other hand, in the thermoelectric oxide material, the number of carriers is electrically large, and electricity flows like a metal, but the carrier moving speed is slow, so that the bias of the carrier distribution due to the temperature difference becomes large, and the thermoelectromotive force. The main material is a material that increases. In the conventional oxygen ion conductor, the oxygen ion conductive material has a low carrier movement speed because the carrier movement is oxygen ion conduction in the crystal, and the thermoelectromotive force is large on the order of several mV, but compared with the thermoelectric material. Many materials have low electrical conductivity.
しかるに、燃料電池電極として検討されている層状酸化鉄系材料では、酸素イオン伝導性が低温でも速く、キャリア伝導性が高い（抵抗が低い）ことが知られており、その中でも、上述の特定の酸化鉄系化合物のような組成の結晶性化合物は、“高速イオン伝導体”材料として注目されている。このような高速イオン伝導体では、温度条件によって、従来の酸素イオン伝導体に比べて、低い抵抗を持つとともに、酸素イオン伝導キャリアといった制限されたポンピング伝導のため、比較的高い熱起電力も得られることが期待できる。 However, it is known that the layered iron oxide-based material being studied as a fuel cell electrode has a high oxygen ion conductivity even at a low temperature and a high carrier conductivity (low resistance). Crystalline compounds having a composition such as iron oxide compounds are attracting attention as “fast ion conductor” materials. Such fast ion conductors have a lower resistance than conventional oxygen ion conductors due to temperature conditions, and also have a relatively high thermoelectromotive force due to limited pumping conduction such as oxygen ion conduction carriers. Can be expected.
このような酸素イオン伝導体でかつ熱電変換機能を有する酸化物材料を、例えば、ＳＯＦＣのような酸化物系の燃料電池の電極として利用すれば、従来の燃料電池反応とともに、電極での発熱を利用する熱電変換機能も付加することができ、上記の化学反応場での直接的な廃熱回収も可能となることが考えられる。これらの技術的課題を実現するためには、イオン伝導性材料及び熱電変換機能を有する材料を開発し、水素や炭化水素等の高温燃料が流通し、材料上に温度差を形成する構造を造ることが必要となると考えられる。 If such an oxygen ion conductor and an oxide material having a thermoelectric conversion function are used as an electrode of an oxide fuel cell such as SOFC, for example, heat generation at the electrode is generated together with the conventional fuel cell reaction. It is conceivable that a thermoelectric conversion function to be used can also be added, and direct waste heat recovery in the above chemical reaction field is also possible. In order to realize these technical issues, we develop ion conductive materials and materials with thermoelectric conversion function, and create structures that allow high-temperature fuels such as hydrogen and hydrocarbons to flow and form temperature differences on the materials. It is considered necessary.
このような状況の中で、本発明者らは、上記従来技術に鑑みて、上述のような問題を解決することが可能で、燃料電池のようなセル反応場直下で熱エネルギーを回収することができる新しい材料及び構造の熱電素子を開発することを目標として鋭意研究を積み重ねた結果、イオン伝導性かつ熱電変換機能を有する材料の開発、該材料上に温度差を形成する構造を造ることに成功し、本発明を完成するに至った。 Under such circumstances, the present inventors can solve the above-mentioned problems in view of the above prior art, and recover thermal energy directly under a cell reaction field such as a fuel cell. As a result of intensive research with the goal of developing a new material and structure thermoelectric element that can be used, the development of a material that has ion conductivity and a thermoelectric conversion function, and a structure that forms a temperature difference on the material The present invention has been completed successfully.
本発明は、イオン伝導性かつ熱電変換機能を有する熱電材料、該材料を用いた熱電変換素子、及び、これにガス流通が可能な構造を付与した、高温燃料ガスを流通させ、素子上の加熱並びに発熱反応による温度差で熱電変換発電へ利用することが可能な多層熱電変換システムを提供することを目的とするものである。 The present invention relates to a thermoelectric material having an ion conductivity and a thermoelectric conversion function, a thermoelectric conversion element using the material, and a high-temperature fuel gas provided with a structure capable of gas distribution, and heating on the element. It is another object of the present invention to provide a multilayer thermoelectric conversion system that can be used for thermoelectric power generation with a temperature difference caused by an exothermic reaction.
上記課題を解決するための本発明は、以下の技術的手段から構成される。
（１）鉄、コバルト、ニッケル、バリウム及びストロンチウムから構成される結晶性酸化物で、ＡＦｅ１−ｙＢｙＯ３又はＡ４Ｆｅ６−ｘＢｘＯ１３の（Ａ＝Ｓｒ，ＢａもしくはＳｒ：Ｂａ＝１：１，Ｂ＝Ｃｏ，Ｎｉ，ｘ＝０．０−０．８）の組成を有し、熱電起電力を発現する熱電材料。
（２）上記組成の結晶性化合物で、結晶学的に層状結晶構造を有する酸化鉄系化合物からなる、前記（１）記載の熱電材料。
（３）酸素欠陥の形成により、酸素イオン伝導性を有する、前記（１）記載の熱電材料。
（４）円筒状又は棒状に成形し、高温ガスを円筒状の内側又は棒状の片側へあて、円筒状の外側もしくは棒状の他の片方を低温のガスで冷却し、材料間へ温度差を形成したときに、電圧が生じる、前記（１）記載の熱電材料。
（５）単結晶もしくは多結晶のセラミックスとして上記形状を付与した、前記（４）記載の熱電材料。
（６）前記（１）から（５）のいずれかに記載の熱電材料の層と、イオン伝導性又は電子伝導性を発現する酸化物セラミックスの層を多層に形成した多層熱電変換素子。
（７）熱電材料の内側に、酸化セリウム、酸化ジルコニウム、酸化ニッケル、酸化コバルト、酸化鉄、酸化マンガン、及びそれらに、ランタン、サマリウム、ガドリニウム、イットリウム、スカンジウム、ストロンチウム、バリウム、カルシウムのいずれかの金属元素が１．０−２０．０ｍｏｌ％含まれ、イオン伝導性又は電子伝導性を発現する酸化物セラミックの層を１０−１００μｍの厚さで１層又は２層形成した、前記（６）記載の多層熱電変換素子。
（８）上記熱電材料の酸素欠陥及び酸素イオン伝導性を利用して、大気中の酸素を取り込み、内側の酸化物セラミックス層の電解質もしくは電極を利用して、燃料ガスとの電気化学反応による発電を行う、前記（７）記載の多層熱電変換素子。
（９）上記熱電材料の内側に形成した酸化物セラミックス層が、燃料ガスとの化学反応により発熱し、温度差を向上させ、熱電変換での熱起電力を向上させる、前記（７）記載の多層熱電変換素子。
（１０）上記燃料ガスが、水素又は炭化水素である、前記（８）又は（９）記載の多層熱電変換素子。
（１１）前記（６）から（１０）のいずれかに記載の多層熱電変換素子を用いて形成したガス流通構造に、高温燃料ガスを流通させ、素子上の加熱量並びに発熱反応による温度差で熱電変換発電を行う多層熱電変換システム。
（１２）高温ガスとして、加熱した水素、又は炭化水素、酸素、窒素、二酸化炭素、一酸化炭素、もしくはガソリン、軽油、アルコール、もしくは天然ガスを燃焼させた排気ガスを利用する、前記（１１）記載の多層熱電変換システム。
The present invention for solving the above-described problems comprises the following technical means.
(1) iron, cobalt, nickel, crystalline oxide composed of barium and strontium, the AFe 1-y B y O 3 or A 4 Fe 6-x B x O 13 (A = Sr, Ba or Sr : Ba = 1: 1, B = Co, Ni, x = 0.0-0.8), and a thermoelectric material that develops thermoelectric power.
(2) The thermoelectric material according to (1), wherein the thermoelectric material is a crystalline compound having the above-described composition and comprising an iron oxide compound having a layered crystal structure crystallographically.
(3) The thermoelectric material according to (1), wherein the thermoelectric material has oxygen ion conductivity due to formation of oxygen defects.
(4) Molded into a cylinder or rod, hot gas is applied to the inside of the cylinder or one side of the rod, and the other side of the cylinder or the other side of the rod is cooled with a low temperature gas to form a temperature difference between the materials. The thermoelectric material according to the above (1), in which voltage is generated when
(5) The thermoelectric material according to (4), wherein the shape is given as a single crystal or polycrystalline ceramic.
(6) A multilayer thermoelectric conversion element in which the thermoelectric material layer according to any one of (1) to (5) above and a layer of oxide ceramics exhibiting ionic conductivity or electronic conductivity are formed in multiple layers.
(7) Inside the thermoelectric material, any one of cerium oxide, zirconium oxide, nickel oxide, cobalt oxide, iron oxide, manganese oxide, and lanthanum, samarium, gadolinium, yttrium, scandium, strontium, barium, calcium The said (6) description which formed the layer of the oxide ceramic which contains 1.0-20.0 mol% of metal elements, and expresses ion conductivity or electronic conductivity with the thickness of 10-100 micrometers. Multilayer thermoelectric conversion element.
(8) Utilizing oxygen defects and oxygen ion conductivity of the thermoelectric material, taking in oxygen in the atmosphere, and using the electrolyte or electrode of the inner oxide ceramic layer to generate power by electrochemical reaction with fuel gas The multilayer thermoelectric conversion element according to (7), wherein:
(9) The oxide ceramic layer formed inside the thermoelectric material generates heat due to a chemical reaction with the fuel gas, improves a temperature difference, and improves a thermoelectromotive force in thermoelectric conversion. Multi-layer thermoelectric conversion element.
(10) The multilayer thermoelectric conversion element according to (8) or (9), wherein the fuel gas is hydrogen or hydrocarbon.
(11) A high-temperature fuel gas is circulated through the gas circulation structure formed using the multilayer thermoelectric conversion element according to any one of (6) to (10) above, and the temperature difference due to the heating amount and exothermic reaction on the element. A multilayer thermoelectric conversion system that performs thermoelectric power generation.
(12) As the high-temperature gas, heated hydrogen, or exhaust gas obtained by burning hydrocarbon, oxygen, nitrogen, carbon dioxide, carbon monoxide, gasoline, light oil, alcohol, or natural gas is used (11) The multilayer thermoelectric conversion system described.
次に、本発明について更に詳細に説明する。
本発明は、鉄、コバルト、ニッケル、バリウム及びストロンチウムから構成される結晶性酸化物で、ＡＦｅ１−ｙＢｙＯ３又はＡ４Ｆｅ６−ｘＢｘＯ１３の（Ａ＝Ｓｒ，ＢａもしくはＳｒ：Ｂａ＝１：１，Ｂ＝Ｃｏ，Ｎｉ，ｘ＝０．０−０．８）の組成を有し、熱電起電力を発現する熱電材料の点に特徴を有するものである。
Next, the present invention will be described in more detail.
The present invention is a crystalline oxide composed of iron, cobalt, nickel, barium and strontium, and is composed of AFe 1-y B y O 3 or A 4 Fe 6-x B x O 13 (A = Sr, Ba or Sr: Ba = 1: 1, B = Co, Ni, x = 0.0-0.8), and is characterized by a thermoelectric material that develops thermoelectric power.
本発明では、上記組成の結晶性化合物で、結晶学的に層状結晶構造を有する酸化鉄系化合物からなること、酸素欠陥の形成により、酸素イオン伝導性を有すること、円筒状又は棒状に成形し、高温ガスを円筒状の内側又は棒状の片側へあて、円筒状の外側もしくは棒状の他の片方を低温のガスで冷却し、材料間へ温度差を形成したときに、電圧が生じること、単結晶もしくは多結晶のセラミックスとして上記形状を付与したこと、を好ましい実施の態様としている。 In the present invention, the crystalline compound is composed of an iron oxide compound having a layered crystal structure crystallographically, has oxygen ion conductivity by forming oxygen defects, and is formed into a cylindrical shape or a rod shape. When a high temperature gas is applied to the inside of the cylinder or one side of the rod and the other side of the cylinder or the other of the rod is cooled with a low temperature gas to form a temperature difference between the materials, a voltage is generated. A preferred embodiment is that the above shape is imparted as a crystalline or polycrystalline ceramic.
また、本発明は、上記の熱電材料の層と、イオン伝導性又は電子伝導性を発現する酸化物セラミックスの層を多層に形成した多層熱電変換素子の点に特徴を有するものである。本発明では、熱電材料の内側に、酸化セリウム、酸化ジルコニウム、酸化ニッケル、酸化コバルト、酸化鉄、酸化マンガン、及びそれらに、ランタン、サマリウム、ガドリニウム、イットリウム、スカンジウム、ストロンチウム、バリウム、カルシウムのいずれかの金属元素が１．０−２０．０ｍｏｌ％含まれ、イオン伝導性又は電子伝導性を発現する酸化物セラミックの層を１０−１００μｍの厚さで１層又は２層形成したこと、を好ましい実施の態様としている。 Further, the present invention is characterized by a multilayer thermoelectric conversion element in which a layer of the thermoelectric material described above and a layer of oxide ceramics exhibiting ionic conductivity or electron conductivity are formed in multiple layers. In the present invention, inside the thermoelectric material, any one of cerium oxide, zirconium oxide, nickel oxide, cobalt oxide, iron oxide, manganese oxide, and lanthanum, samarium, gadolinium, yttrium, scandium, strontium, barium, calcium 1 to 20.0 mol% of the metal element, and an oxide ceramic layer that expresses ionic conductivity or electronic conductivity is formed in a thickness of 10 to 100 μm in one or two layers. It is as an aspect.
また、本発明では、上記熱電材料の酸素欠陥及び酸素イオン伝導性を利用して、大気中の酸素を取り込み、内側の酸化物セラミックス層の電解質もしくは電極を利用して、燃料ガスとの電気化学反応による発電を行うこと、上記熱電材料の内側に形成した酸化物セラミックス層が、燃料ガスとの化学反応により発熱し、温度差を向上させ、熱電変換での熱起電力を向上させること、上記燃料ガスが、水素又は炭化水素であること、を好ましい実施の態様としている。 In the present invention, oxygen in the atmosphere is taken in by utilizing oxygen defects and oxygen ion conductivity of the thermoelectric material, and an electrolyte or electrode of the inner oxide ceramic layer is used to perform electrochemical reaction with fuel gas. Performing power generation by reaction, the oxide ceramic layer formed inside the thermoelectric material generates heat due to a chemical reaction with the fuel gas, improves the temperature difference, and improves the thermoelectromotive force in thermoelectric conversion, A preferred embodiment is that the fuel gas is hydrogen or hydrocarbon.
更に、本発明は、上記の多層熱電変換素子を用いて形成したガス流通構造に、高温燃料ガスを流通させ、素子上の加熱量並びに発熱反応による温度差で熱電変換発電を行う多層熱電変換システムの点に特徴を有するものである。本発明では、高温ガスとして、加熱した水素、又は炭化水素、酸素、窒素、二酸化炭素、一酸化炭素、もしくはガソリン、軽油、アルコール、もしくは天然ガスを燃焼させた排気ガスを利用すること、を好ましい実施の態様としている。 Furthermore, the present invention provides a multilayer thermoelectric conversion system in which a high-temperature fuel gas is circulated through a gas circulation structure formed using the multilayer thermoelectric conversion element, and thermoelectric conversion power generation is performed with a temperature difference due to the heating amount and exothermic reaction on the element. It is characterized by the following points. In the present invention, it is preferable to use heated hydrogen or exhaust gas obtained by burning hydrocarbon, oxygen, nitrogen, carbon dioxide, carbon monoxide, gasoline, light oil, alcohol, or natural gas as the high-temperature gas. This is an embodiment.
本発明では、鉄、コバルト、ニッケル、バリウム及びストロンチウムから構成される結晶性酸化物で、ＡＦｅ１−ｙＢｙＯ３又はＡ４Ｆｅ６−ｘＢｘＯ１３の（Ａ＝Ｓｒ，ＢａもしくはＳｒ：Ｂａ＝１：１，Ｂ＝Ｃｏ，Ｎｉ，ｘ＝０．０−０．８）の組成を有し、熱電起電力を発現する熱電材料をモル比で所定量混合し、例えば、ボールミル等で２４時間程度乾式混合し、約１０００℃で６時間焼成し、更に、２４時間程度乾式粉砕混合後、約１２００℃で４時間程度焼成し、Ａ４Ｆｅ６−ｘＢｘＯ１３（Ａ＝Ｓｒ，ＢａもしくはＳｒ：Ｂａ＝１：１，Ｂ＝Ｃｏ，Ｎｉ，ｘ＝０．０−０．８）の組成及び結晶相の材料を合成することで、酸素欠陥構造を形成しやすい層状のペロブスカイト型結晶相を有する熱電材料を得ることができる。 In the present invention, iron, cobalt, nickel, crystalline oxide composed of barium and strontium, (A = Sr the AFe 1-y B y O 3 or A 4 Fe 6-x B x O 13, Ba or Sr: Ba = 1: 1, B = Co, Ni, x = 0.0-0.8), and a predetermined amount of a thermoelectric material that expresses thermoelectric power is mixed in a molar ratio. For example, a ball mill Etc. for about 24 hours, and calcined at about 1000 ° C. for 6 hours. After further dry grinding and mixing for about 24 hours, calcined at about 1200 ° C. for about 4 hours, A 4 Fe 6-x B x O 13 (A = Sr, Ba or Sr: Ba = 1: 1, B = Co, Ni, x = 0.0-0.8) by synthesizing a material having a composition and a crystal phase, a layer shape in which an oxygen defect structure is easily formed A thermoelectric material having a perovskite crystal phase It can be.
上記方法により合成した材料を、例えば、約１２００℃で４時間程度焼成した材料は、ｘ＝０．０−０．８の範囲の全てにおいて、１００−８００℃にて２００μＶ／Ｋ以上の大きな熱起電力と導電性（＜１０ Ｏｈｍ ｃｍ以下）を示し、熱電素子としての機能を有している。ｘ＝０．３、Ａ＝Ｓｒ，Ｂ＝Ｃｏの熱電特性は、図４に示されるように、２００−８００℃で２２０〜３４０μＶ／Ｋの熱起電力、４００−８００℃で１．０ｓ／ｃｍ（１ Ｏｈｍ ｃｍ）の導電率であった。 The material synthesized by the above method is, for example, a material obtained by firing at about 1200 ° C. for about 4 hours, and has a large heat of 200 μV / K or more at 100-800 ° C. in the entire range of x = 0.0-0.8. It exhibits electromotive force and conductivity (<10 Ohm cm or less) and has a function as a thermoelectric element. As shown in FIG. 4, the thermoelectric characteristics of x = 0.3, A = Sr, B = Co are as follows: the thermoelectromotive force of 220 to 340 μV / K at 200 to 800 ° C., 1.0 s / at 400 to 800 ° C. The conductivity was cm (1 Ohm cm).
上記熱電材料を、例えば、セルロース系バインダーと水で混練し、例えば、内径１０ｍｍ、外径２０ｍｍ等の円筒状の形状に押出せる口金より押出、乾燥、脱脂後、１２００℃程度で焼成することにより、円筒型セラミック熱電変換素子を製造することができる。これらの具体的な構成は、製品の種類、大きさ等に応じて任意に選択し、設計することができる。 By kneading the thermoelectric material with, for example, a cellulose-based binder and water, and extruding, drying, and degreasing from a die that can be extruded into a cylindrical shape such as an inner diameter of 10 mm and an outer diameter of 20 mm, and firing at about 1200 ° C. A cylindrical ceramic thermoelectric conversion element can be manufactured. These specific configurations can be arbitrarily selected and designed according to the type, size, etc. of the product.
次に、多層構造を有する円筒型熱電素子の製造例について説明する。まず、上述の熱電材料を、上記円筒型セラミック熱電変換素子の製造例と同様にして円筒状に成形し、焼成して、熱電変換セラミック材料層を形成する。次に、イオン電導性材料を有機系バインダーに分散し、テープ状に成形したもの（セラミック材料２）を筒状に形成し、次に、上記熱電材料をイソプロパノール等に分散して製造したセラミックペーストを上記円筒の表面に貼付けた後、これらを、上述の円筒型熱電素子の内側に固定し、焼成して、多層熱電変換素子を製造する。 Next, an example of manufacturing a cylindrical thermoelectric element having a multilayer structure will be described. First, the thermoelectric material described above is formed into a cylindrical shape and fired to form a thermoelectric conversion ceramic material layer in the same manner as in the manufacturing example of the cylindrical ceramic thermoelectric conversion element. Next, a ceramic paste produced by dispersing an ion conductive material in an organic binder, forming a tape shape (ceramic material 2) into a cylindrical shape, and then dispersing the thermoelectric material in isopropanol or the like. Are affixed to the surface of the cylinder and then fixed to the inside of the cylindrical thermoelectric element described above and fired to produce a multilayer thermoelectric conversion element.
本発明により、リアクター層、及び熱電材料層を形成した円筒型熱電素子を作製し、提供することができる。本発明では、酸素イオン伝導機能及び熱電変換機能を併せもつ、電極及び熱電変換材料として利用することが可能な熱電変換素子を構築することができる。本発明の酸化物材料を、例えば、酸化物系の燃料電池の電極として利用することで、燃料電池反応とともに、電極での発熱を利用する熱電変換機能を付加して、上記電極における化学反応場での直接的な廃熱回収が可能となり、例えば、水素、炭化水素等の化学エネルギーからの燃料電池反応による電力エネルギーへの変換、回収により、エネルギー利用効率の高い燃料電池の構築及び利用が実現可能となる。 According to the present invention, a cylindrical thermoelectric element in which a reactor layer and a thermoelectric material layer are formed can be produced and provided. In the present invention, a thermoelectric conversion element having both an oxygen ion conduction function and a thermoelectric conversion function and usable as an electrode and a thermoelectric conversion material can be constructed. The oxide material of the present invention is used, for example, as an electrode of an oxide-based fuel cell, thereby adding a thermoelectric conversion function that utilizes heat generated by the electrode together with the fuel cell reaction, and a chemical reaction field in the electrode. For example, it is possible to construct and use fuel cells with high energy use efficiency by converting and recovering chemical energy such as hydrogen and hydrocarbons into electric energy by fuel cell reaction. It becomes possible.
本発明では、鉄、コバルト、ニッケル、バリウム及びストロンチウムから構成される結晶性酸化物で、ＡＦｅ１−ｙＢｙＯ３又はＡ４Ｆｅ６−ｘＢｘＯ１３の（Ａ＝Ｓｒ，ＢａもしくはＳｒ：Ｂａ＝１：１，Ｂ＝Ｃｏ，Ｎｉ，ｘ＝０．０−０．８）の組成を有し、熱電起電力を発現する熱電材料を使用することが重要であり、材料の混合、焼成の方法及び手段、それらの条件等については特に制限されるものではなく、任意に設計及び設定することができる。また、熱電材料に構造を付与するための、押出成形、セラミック材料の組成、調製方法及び手段、テープ成形、ペーストの組成、調製方法及び手段、ペーストによる貼付方法及び手段、焼成方法、手段及び条件、多層の形状及び構造等についても、製品の使用目的に応じて任意に設計、設定することができる。 In the present invention, iron, cobalt, nickel, crystalline oxide composed of barium and strontium, (A = Sr the AFe 1-y B y O 3 or A 4 Fe 6-x B x O 13, Ba or It is important to use a thermoelectric material having a composition of Sr: Ba = 1: 1, B = Co, Ni, x = 0.0−0.8) and expressing a thermoelectric power, and mixing of the materials The firing method and means, conditions thereof and the like are not particularly limited, and can be arbitrarily designed and set. Also, extrusion, ceramic material composition, preparation method and means, tape forming, paste composition, preparation method and means, paste application method and means, firing method, means and conditions for imparting a structure to the thermoelectric material The multilayer shape and structure can be arbitrarily designed and set according to the intended use of the product.
本発明は、上述の材料組成を変え、イオン伝導性を有する結晶性酸化鉄系材料を合成し、電気特性及び熱電特性を発現する熱電材料を提供し、そして、既存のセラミック部材の製造に用いられる、押出成形、加圧成形、テープ成形、ディップコーティング並びに塗布コーティング等を利用して、例えば、図１及び図２に具体的に示されるような手法により、多層構造を持つ熱電素子を製造し、更に、ガス流通が可能な構造を付与し、高温燃料ガスを流通させ、素子上の加熱並びに発熱反応による温度差での熱電変換発電への利用を可能とするものである。更に、本発明は、上述の多層熱電変換素子の構造により、高温ガス中の水素又は炭化水素種の素子上での酸素イオン伝導を介する反応による、燃料電池発電時の熱電発電への利用と、高温ガスからの電力の形成による、化学反応場での直接的かつ複合的な発電を行うことができる熱電発電素子への利用を、実現可能とするものである。 The present invention provides a thermoelectric material that changes the above-described material composition, synthesizes a crystalline iron oxide-based material having ionic conductivity, and exhibits electrical and thermoelectric properties, and is used for manufacturing an existing ceramic member. A thermoelectric element having a multilayer structure is manufactured by, for example, a technique specifically shown in FIGS. 1 and 2 by using extrusion molding, pressure molding, tape molding, dip coating and coating coating. Furthermore, a structure capable of gas circulation is provided, and high-temperature fuel gas is circulated so that it can be used for thermoelectric conversion power generation with a temperature difference due to heating and exothermic reaction on the element. Furthermore, the present invention uses the multilayer thermoelectric conversion element described above for use in thermoelectric power generation during fuel cell power generation by reaction via oxygen ion conduction on a hydrogen or hydrocarbon species element in a high-temperature gas; The present invention makes it possible to realize use in a thermoelectric power generation element capable of performing direct and combined power generation in a chemical reaction field by forming electric power from high-temperature gas.
本発明により、次のような効果が奏される。
（１）イオン伝導性かつ熱電変換機能を有する新しい熱電材料を提供することができる。
（２）上記熱電材料を用いて作製した多層構造をもつ熱電素子を提供することができる。
（３）上記熱電素子にガス流通が可能な構造を付与し、高温燃料ガスを流通させ、素子上の加熱量並びに発熱反応による温度差で熱電変換発電を可能とする多層構造を有する熱電変換発電システムを提供することができる。
（４）本発明の熱電素子を利用することにより、高温ガスからの電力の形成により、化学反応場での直接的かつ複合的な発電を行うことができる熱電発電素子を構築し、提供することができる。
（５）例えば、燃焼排ガス中の炭化水素や一酸化炭素を原料として、本発明の熱電素子上における電気化学反応での電力エネルギーの回収、及び熱電変換での電力エネルギー及び相互を合わせた高効率な電力エネルギーの回収ができる。
（６）これらの熱電材料を用い、高温ガスをともなう廃エネルギー等の回収が可能なデバイスの製造が可能となる。
（７）微小な回収エネルギーの蓄積により、トータルな化学エネルギーの変換効率の向上に利用できる。
The present invention has the following effects.
(1) A new thermoelectric material having ion conductivity and a thermoelectric conversion function can be provided.
(2) A thermoelectric element having a multilayer structure manufactured using the thermoelectric material can be provided.
(3) Thermoelectric conversion power generation having a multilayer structure in which a structure capable of gas flow is imparted to the thermoelectric element, high temperature fuel gas is circulated, and thermoelectric power generation is possible by a temperature difference due to heating amount and exothermic reaction on the element. A system can be provided.
(4) By using the thermoelectric element of the present invention, a thermoelectric power generation element capable of performing direct and combined power generation in a chemical reaction field by forming electric power from high-temperature gas is provided and provided. Can do.
(5) For example, using hydrocarbons and carbon monoxide in combustion exhaust gas as raw materials, recovery of power energy in electrochemical reaction on the thermoelectric element of the present invention, and high efficiency combining power energy and mutual in thermoelectric conversion Power energy can be recovered.
(6) Using these thermoelectric materials, it is possible to manufacture a device capable of recovering waste energy accompanied by high-temperature gas.
(7) Accumulation of minute recovered energy can be used to improve total chemical energy conversion efficiency.
以下、実施例により本発明を具体的に説明するが、本発明は、これらの実施例によって何ら限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples.
（１）熱電材料の合成
燃料電池等の電極材料として利用可能な材料、特に、空気中より酸素イオンを材料中へ取り込める酸素欠陥をもつ結晶性の酸化鉄系材料について、更に、温度差により熱起電力を発現する材料の探索を目的として、酸化鉄、酸化コバルト、炭酸ストロンチウム、炭酸バリウム又は酸化ニッケルを、ＡＦｅ１−ｙＢｙＯ３又はＡ４Ｆｅ６−ｘＢｘＯ１３の（Ａ＝Ｓｒ，ＢａもしくはＳｒ：Ｂａ＝１：１，Ｂ＝Ｃｏ，Ｎｉ，ｘ＝０．０−０．８）のモル比で所定量混合し、ボールミルにて２４時間乾式混合し、１０００℃で６時間焼成し、更に、２４時間乾式粉砕混合後、１２００℃で４時間焼成し、Ａ４Ｆｅ６−ｘＢｘＯ１３の（Ａ＝Ｓｒ，ＢａもしくはＳｒ：Ｂａ＝１：１，Ｂ＝Ｃｏ，Ｎｉ，ｘ＝０．０−０．８）の組成及び結晶相の材料を合成した。得られた材料の一例について、図３のように、Ｘ線回折にて、酸素欠陥構造を形成しやすい層状のペロブスカイト型結晶相であることを確認した。また、ｘ＝０．０−０．８について、同様な結晶性構造の単一相が得られた。
(1) Synthesis of thermoelectric materials Materials that can be used as electrode materials for fuel cells, especially crystalline iron oxide materials that have oxygen defects that allow oxygen ions to be taken into the material from the air. for the purpose of searching for materials that expresses an electromotive force, iron oxide, cobalt oxide, strontium carbonate, barium carbonate or nickel oxide, AFe 1-y B y O 3 or a 4 Fe 6-x B x of O 13 (a = Sr, Ba or Sr: Ba = 1: 1, B = Co, Ni, x = 0.0-0.8), and a predetermined amount of the mixture is mixed by dry mixing in a ball mill for 24 hours. Baking for 6 hours, followed by 24 hours of dry pulverization and mixing, followed by baking at 1200 ° C. for 4 hours, and A 4 Fe 6-x B x O 13 (A = Sr, Ba or Sr: Ba = 1: 1, B = Co, Ni, x = 0.0 The composition and crystalline phase materials 0.8) were synthesized. An example of the obtained material was confirmed by X-ray diffraction to be a layered perovskite crystal phase that easily forms an oxygen defect structure as shown in FIG. Moreover, the single phase of the same crystalline structure was obtained about x = 0.0-0.8.
（２）熱電素子の作製
上記（１）で合成した試料を、５ｘ５ｘ２０ｍｍの棒状に成形し、１２００℃で４時間焼成した結果、ｘ＝０．０−０．８についての全てで、１００−８００℃にて２００μＶ／Ｋ以上の大きな熱起電力と導電性（＜１０ Ｏｈｍ ｃｍ以下）が確認され、熱電素子として機能することが分かった。図４に、ｘ＝０．３、Ａ＝Ｓｒ，Ｂ＝Ｃｏでの熱電特性（熱起電力と導電率）の温度変化を示す。
(2) Production of thermoelectric element The sample synthesized in the above (1) was formed into a 5 × 5 × 20 mm rod shape and baked at 1200 ° C. for 4 hours. A large thermoelectromotive force of 200 μV / K or more and electrical conductivity (<10 Ohm cm or less) were confirmed at 0 ° C., and it was found to function as a thermoelectric element. FIG. 4 shows temperature changes in thermoelectric characteristics (thermoelectromotive force and conductivity) at x = 0.3, A = Sr, and B = Co.
上記（１）で得られた材料を、セルロース系バインダーと水で混練し、内径１０ｍｍ、外径２０ｍｍの円筒状の形状に押出せる口金より押出、乾燥、脱脂後、１２００℃で焼成して円筒型セラミック熱電変換素子を作製した。得られた熱電酸化物素子の写真を図５に示す。得られた熱電変換素子は、部分的に孔のある多孔質のセラミックで、本手法及び材料により容易に円筒状の熱電セラミック素子を製造し得た。 The material obtained in (1) above is kneaded with a cellulose binder and water, extruded from a die that can be extruded into a cylindrical shape having an inner diameter of 10 mm and an outer diameter of 20 mm, dried and degreased, and then fired at 1200 ° C. to form a cylinder Type ceramic thermoelectric conversion element was produced. A photograph of the obtained thermoelectric oxide element is shown in FIG. The obtained thermoelectric conversion element was a porous ceramic with a partial pore, and a cylindrical thermoelectric ceramic element could be easily manufactured by this method and material.
（３）多層構造の円筒形熱電素子の製造
次に、図２の多層熱電変換素子製造法のような方法で、多層構造の円筒形熱電素子を製造した。上記（１）の材料を上記（２）と同様に、円筒状に成形し、焼成して円筒状セラミック熱電変換素子を作製した。得られた熱電素子の内側に、低温作動用燃料電池にて利用されるイオン伝導性材料である、Ｃｅ０．９Ｇｄ０．１Ｏ（市販 阿南化成製ＣＧＯ１０／９０）を１０−２０ｖｏｌ％ポリブチラール系有機系バインダーに分散し、テープ状にしたものを筒状にし、これを、上記（１）の材料を３０−４０ｖｏｌ％のイソプロパノールに分散し、製造したセラミックペーストにて同様に貼付け、減圧乾燥機中１５０℃で２時間乾燥後、１−２℃／ｍｉｎで１２００℃で２４時間焼成することにより多層熱電変換素子を製造した。これにより、本材料と本手法により、図６に示すような、リアクター層を有する多層熱電素子を製造し得た。
(3) Manufacture of Multilayer Cylindrical Thermoelectric Element Next, a multi-layered cylindrical thermoelectric element was manufactured by a method such as the multilayer thermoelectric conversion element manufacturing method of FIG. The material (1) was formed into a cylindrical shape and fired in the same manner as (2) above to produce a cylindrical ceramic thermoelectric conversion element. Inside the obtained thermoelectric element, Ce0.9Gd0.1O (commercially available Anan Kasei CGO10 / 90), which is an ion conductive material used in a low-temperature operating fuel cell, is 10-20 vol% polybutyral organic system. Dispersed in a binder and formed into a cylindrical shape, this was dispersed in 30-40 vol% isopropanol of the material of the above (1) and pasted in the same manner with the produced ceramic paste. A multilayer thermoelectric conversion element was manufactured by drying at 1200 ° C. for 24 hours at 1-2 ° C./min after drying at 2 ° C. for 2 hours. Thereby, the multilayer thermoelectric element which has a reactor layer as shown in FIG. 6 with this material and this method could be manufactured.
以上詳述したように、本発明は、熱電材料、熱電変換素子、及び多層熱電変換システムに係るものであり、本発明により、リアクター構造を有する熱電材料、特に、ガス反応に利用可能な円筒状の熱電素子を製造し、提供することができる。この技術を利用することにより、水素、炭化水素を含む原料又は燃焼ガスを熱電素子に流通させることにより、廃熱による熱電変換発電とともに、燃料電池反応による発熱による素子上の温度差により、熱起電力を生じ、廃熱エネルギーと化学エネルギーを同時に回収可能な、高効率かつ高度集積によるコンパクトな熱電素子の製造が可能となる。また、それらの素子を利用するモジュールにより、これまで回収できなかったエネルギーを有効に利用できるようになるため、新しいエネルギー回収ユニット等の開発が可能となる。 As described above in detail, the present invention relates to a thermoelectric material, a thermoelectric conversion element, and a multilayer thermoelectric conversion system. According to the present invention, a thermoelectric material having a reactor structure, particularly a cylindrical shape that can be used for a gas reaction. The thermoelectric element can be manufactured and provided. By using this technology, hydrogen, hydrocarbon-containing raw materials or combustion gases are circulated through the thermoelectric elements, so that heat generation is caused not only by thermoelectric conversion power generation due to waste heat but also by temperature differences on the elements due to heat generated by the fuel cell reaction. It is possible to produce a compact thermoelectric element with high efficiency and high integration that can generate electric power and simultaneously recover waste heat energy and chemical energy. In addition, the modules that use these elements can effectively use energy that could not be recovered so far, so that a new energy recovery unit or the like can be developed.
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