JP2011102658A - Method of recovering sensible heat from exhaust gas generated from metallurgical furnace and method of cooling exhaust gas generated from metallurgical furnace - Google Patents

Method of recovering sensible heat from exhaust gas generated from metallurgical furnace and method of cooling exhaust gas generated from metallurgical furnace Download PDF

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JP2011102658A
JP2011102658A JP2009256865A JP2009256865A JP2011102658A JP 2011102658 A JP2011102658 A JP 2011102658A JP 2009256865 A JP2009256865 A JP 2009256865A JP 2009256865 A JP2009256865 A JP 2009256865A JP 2011102658 A JP2011102658 A JP 2011102658A
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exhaust gas
reaction
metallurgical furnace
carbon dioxide
steam
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JP2011102658A5 (en
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Katsuhiko Takagi
克彦 高木
Hitoshi Saima
等 斉間
Hiroshi Kishimoto
啓 岸本
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JFE Steel Corp
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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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/30—Technologies for a more efficient combustion or heat usage
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
    • Y02P10/143—Reduction of greenhouse gas [GHG] emissions of methane [CH4]
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

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  • Manufacture Of Iron (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of indirectly and efficiently recovering sensible heat from a high-temperature exhaust gas of about 800°C or more generated from a metallurgical furnace such as a converter furnace, a smelting reduction furnace and an electric furnace, and efficiently cooling the high-temperature exhaust gas by the endothermic chemical reaction. <P>SOLUTION: Any one or more of endothermic chemical reactions of steam-reforming reaction for reforming a reducing agent by steam, a carbon dioxide gas reforming reaction for reforming the reducing agent by carbon dioxide, and a thermal decomposition reaction for thermally decomposing the reducing agent, are induced in a heat exchange tube disposed in an exhaust gas duct of the metallurgical furnace with or without a catalyst while applying the high-temperature exhaust gas discharged from the metallurgical furnace as a heat source, thus the reaction product is carburetted, and the high-temperature exhaust gas is cooled. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、製鉄設備、特に、転炉や溶融還元炉のような冶金炉から発生する高温排ガスの顕熱を、吸熱化学反応を利用して回収する冶金炉発生排ガスからの顕熱回収方法と、上記吸熱化学反応を利用して高温排ガスを冷却する冶金炉発生排ガスの冷却方法に関するものである。   The present invention relates to a method for recovering sensible heat from a metallurgical furnace-generated exhaust gas that recovers sensible heat of a high-temperature exhaust gas generated from a metallurgical furnace such as a converter or a smelting reduction furnace using an endothermic chemical reaction. The present invention relates to a method for cooling a metallurgical furnace-generated exhaust gas that cools a high-temperature exhaust gas using the endothermic chemical reaction.

近年、地球環境を保護し、地球温暖化を防止するために、炭酸ガス排出量の削減が重要な課題となっている。特に、製鉄所における炭酸ガス排出量の削減は、企業の存続にも関わる最も重要な課題となっている。従来から、そのための各種研究がなされてきたが、本格的な炭酸ガスの削減技術は、未だ確立されていないのが実情である。   In recent years, reducing carbon dioxide emissions has become an important issue in order to protect the global environment and prevent global warming. In particular, reducing carbon dioxide emissions at steelworks has become the most important issue related to the survival of companies. Various studies have been made for this purpose, but the actual situation is that a full-scale carbon dioxide reduction technology has not yet been established.

製鉄所では、転炉や溶融還元炉、電気炉などの冶金炉から、多量の炭酸ガスを含む高温の排ガスが発生している。これらの排ガスには、炭酸ガスの他に、一酸化炭素や水素なども多量に含まれているため、製鉄所内の各種設備を稼動させるエネルギー源として活用されている。また、こうした高温排ガスの顕熱を利用するという観点から、ボイラーに供給して低圧の水蒸気を発生させることで、廃熱を回収することが一般的に行われている。しかし、製鉄所での低圧水蒸気の利用価値は低く、むしろ高温の排ガスをそのまま化学的に活用する技術の開発が望まれている。   In steelworks, high-temperature exhaust gas containing a large amount of carbon dioxide gas is generated from metallurgical furnaces such as converters, smelting reduction furnaces, and electric furnaces. Since these exhaust gases contain a large amount of carbon monoxide and hydrogen in addition to carbon dioxide, they are used as an energy source for operating various facilities in the steelworks. Further, from the viewpoint of utilizing the sensible heat of such high-temperature exhaust gas, it is generally performed to recover waste heat by supplying it to a boiler and generating low-pressure steam. However, the utility value of low-pressure steam at steelworks is low, and rather, development of a technology for chemically utilizing high-temperature exhaust gas as it is is desired.

メタンなどの各種炭化水素やメタノール、ジメチルエーテルなどの含酸素化合物等は、炭酸ガスや水蒸気と反応して一酸化炭素や水素に改質されることが知られている。この反応を利用した廃熱回収技術として、例えば、特許文献１には、転炉等の精錬設備から発生する二酸化炭素や水蒸気を含む高温の排ガス中に、炭化水素を含む気体および／または液体を供給して、例えば、下記（１）式のような改質反応を起こさせ、排ガス中の一酸化炭素と水素の増量を図ることにより、排ガスの潜熱を増大させる「増熱」技術が開示されている。
記
ＣＨ４＋ＣＯ２ → ２ＣＯ＋２Ｈ２ ・・・（１） It is known that various hydrocarbons such as methane and oxygen-containing compounds such as methanol and dimethyl ether react with carbon dioxide gas or steam to be reformed to carbon monoxide or hydrogen. As a waste heat recovery technique using this reaction, for example, Patent Document 1 discloses a gas and / or liquid containing hydrocarbons in high-temperature exhaust gas containing carbon dioxide and water vapor generated from a refining facility such as a converter. A “heat increase” technology is disclosed that increases the latent heat of exhaust gas by supplying and causing a reforming reaction such as the following formula (1) to increase the amount of carbon monoxide and hydrogen in the exhaust gas. ing.
CH 4 + CO 2 → 2CO + 2H 2 (1)

また、特許文献２には、転炉から排出されるガスの温度が６００℃以上である位置において石炭を供給し、排ガスと石炭とを対向接触させ、下記（２）式の改質反応を起こさせることによって、一酸化炭素を生成させ、排ガスの増熱を図る技術が開示されている。
記
ＣＯ２＋Ｃ → ２ＣＯ ・・・（２） In Patent Document 2, coal is supplied at a position where the temperature of the gas discharged from the converter is 600 ° C. or higher, the exhaust gas and the coal are brought into contact with each other, and a reforming reaction of the following formula (2) is caused. Thus, a technique for generating carbon monoxide and increasing the heat of exhaust gas is disclosed.
CO 2 + C → 2CO (2)

また、特許文献３には、燃焼炉や内燃機関などの燃焼装置の排気系統に、下記（３）式または（４）式で示されるジメチルエーテル改質反応を起こさせる触媒を充填した熱交換器を設置し、ジメチルエーテルを改質することによって、廃熱回収を行う技術が開示されている。
記
ＣＨ３ＯＣＨ３＋３Ｈ２Ｏ → ６Ｈ２＋２ＣＯ２ ・・・（３）
ＣＨ３ＯＣＨ３＋ＣＯ２ → ３Ｈ２＋３ＣＯ ・・・（４） Patent Document 3 discloses a heat exchanger in which an exhaust system of a combustion apparatus such as a combustion furnace or an internal combustion engine is filled with a catalyst that causes a dimethyl ether reforming reaction represented by the following formula (3) or (4). A technique for recovering waste heat by installing and modifying dimethyl ether is disclosed.
Notation CH 3 OCH 3 + 3H 2 O → 6H 2 + 2CO 2 (3)
CH 3 OCH 3 + CO 2 → 3H 2 + 3CO (4)

特開２０００−２１２６１５号公報JP 2000-212615 A 特開平０５−１１７６６８号公報JP 05-117668 A 特開２００６−０４６３１９号公報JP 2006-046319 A

しかしながら、特許文献１および２に開示されている顕熱回収技術は、排ガス設備内で直接的に改質反応を行う方法であり、熱交換器内で吸熱反応を起こさせて間接的に顕熱回収する方法に比べて、冶金炉の操業条件に左右され易く、自由度に乏しいという欠点がある。また、特許文献３の廃熱回収技術は、熱交換器内で改質反応を行い、間接的に顕熱回収する方法ではあるが、ジメチルエーテル改質反応は、燃焼排ガスのように４００℃前後の温度の排ガスに適応できる技術であり、冶金炉排ガスのように約８００℃以上の高温排ガスには適応できないという問題がある。   However, the sensible heat recovery techniques disclosed in Patent Documents 1 and 2 are methods in which a reforming reaction is directly performed in the exhaust gas facility, and an sensible heat is indirectly generated by causing an endothermic reaction in the heat exchanger. Compared to the method of recovery, there is a drawback that it is easily influenced by the operating conditions of the metallurgical furnace and the degree of freedom is poor. Further, the waste heat recovery technology of Patent Document 3 is a method of performing a reforming reaction in a heat exchanger and indirectly recovering sensible heat, but the dimethyl ether reforming reaction is performed at around 400 ° C. like combustion exhaust gas. This is a technology that can be applied to exhaust gas at a temperature, and there is a problem that it cannot be applied to high-temperature exhaust gas of about 800 ° C. or higher like metallurgical furnace exhaust gas.

上述したように、従来の転炉や溶融還元炉、電気炉などの冶金炉から発生する８００℃程度以上の高温排ガスから顕熱を回収する技術は、排ガス設備内で直接的に改質反応を行っているため、冶金炉の操業条件に左右され、自由度に乏しかったり、あるいは、排ガスダクト内に設置した熱交換器内で間接的に改質反応を行うため、４００℃前後の排ガスにしか適応できなかったりするという問題点を抱えていた。   As described above, the technology for recovering sensible heat from high-temperature exhaust gas of about 800 ° C. or higher generated from metallurgical furnaces such as conventional converters, smelting reduction furnaces, and electric furnaces directly performs the reforming reaction in the exhaust gas equipment. Therefore, the degree of freedom depends on the operating conditions of the metallurgical furnace, or the reforming reaction is indirectly carried out in the heat exchanger installed in the exhaust gas duct, so that only the exhaust gas at around 400 ° C is used. I had the problem of being unable to adapt.

そこで、本発明の目的は、転炉や溶融還元炉、電気炉などの冶金炉から発生する８００℃程度以上の高温排ガスを熱源として熱交換器内で吸熱化学反応を起こさせることにより、冶金炉の操業条件に左右されることなく、高温排ガスの顕熱を間接的に効率よく回収すると共に、上記吸熱化学反応により高温排ガスを効率よく冷却する方法を提案することにある。   Accordingly, an object of the present invention is to cause an endothermic chemical reaction in a heat exchanger by using a high-temperature exhaust gas of about 800 ° C. or higher generated from a metallurgical furnace such as a converter, a smelting reduction furnace, or an electric furnace as a heat source. The present invention proposes a method for efficiently recovering sensible heat of high-temperature exhaust gas indirectly and efficiently cooling the high-temperature exhaust gas by the endothermic chemical reaction without being influenced by the above operating conditions.

従来技術が抱える上述した問題点を克服し、冶金炉から発生する高温排ガスの顕熱を間接的に効率よく回収する本発明は、
冶金炉から排出される高温の排ガスを熱源として、冶金炉の排ガスダクト内に設置された熱交換チューブ内で還元剤を吸熱化学反応させて、その反応生成物を増熱することを特徴とする冶金炉発生排ガスからの顕熱回収方法である。 The present invention, which overcomes the above-mentioned problems of the prior art and indirectly efficiently recovers the sensible heat of the high temperature exhaust gas generated from the metallurgical furnace,
Using the high-temperature exhaust gas discharged from the metallurgical furnace as a heat source, the reductant is subjected to an endothermic chemical reaction in a heat exchange tube installed in the exhaust gas duct of the metallurgical furnace to increase the temperature of the reaction product. This is a method for recovering sensible heat from exhaust gas generated from a metallurgical furnace.

本発明の顕熱回収方法における上記吸熱化学反応は、還元剤を水蒸気で改質する水蒸気改質反応、還元剤を炭酸ガスで改質する炭酸ガス改質反応および還元剤を熱分解する熱分解反応のいずれか１以上の反応であることを特徴とする。   The endothermic chemical reaction in the sensible heat recovery method of the present invention includes a steam reforming reaction in which the reducing agent is reformed with steam, a carbon dioxide reforming reaction in which the reducing agent is reformed with carbon dioxide, and a thermal decomposition in which the reducing agent is thermally decomposed. It is characterized by being any one or more of the reactions.

また、本発明の顕熱回収方法は、上記水蒸気改質反応に、排ガスダクトの蒸気管から発生した水蒸気を用いることを特徴とする。   The sensible heat recovery method of the present invention is characterized in that water vapor generated from a steam pipe of an exhaust gas duct is used for the steam reforming reaction.

また、本発明の顕熱回収方法は、上記炭酸ガス改質反応に、冶金炉から発生する排ガス中の炭酸ガスを用いることを特徴とする。   The sensible heat recovery method of the present invention is characterized in that carbon dioxide in exhaust gas generated from a metallurgical furnace is used for the carbon dioxide reforming reaction.

また、本発明の顕熱回収方法は、上記熱交換チューブとして、転炉排ガス処理設備に設けられた接触ボイラーを用いることを特徴とする。   The sensible heat recovery method of the present invention is characterized in that a contact boiler provided in a converter exhaust gas treatment facility is used as the heat exchange tube.

また、本発明の顕熱回収方法は、上記吸熱化学反応を、固定床触媒の存在下で行うことを特徴とする。   The sensible heat recovery method of the present invention is characterized in that the endothermic chemical reaction is performed in the presence of a fixed bed catalyst.

また、本発明の顕熱回収方法は、上記固定床触媒が、転炉ダストを含む成型物であることを特徴とする。   The sensible heat recovery method of the present invention is characterized in that the fixed bed catalyst is a molded article containing converter dust.

また、本発明は、冶金炉から排出される高温の排ガスを熱源として、冶金炉の排ガスダクト内に設置された熱交換チューブ内で還元剤を吸熱化学反応させることにより、上記高温の排ガスを冷却することを特徴とする冶金炉発生排ガスの冷却方法を提案する。   Further, the present invention cools the high-temperature exhaust gas by causing the reducing agent to undergo an endothermic chemical reaction in a heat exchange tube installed in the exhaust gas duct of the metallurgical furnace using the high-temperature exhaust gas discharged from the metallurgical furnace as a heat source. We propose a method for cooling the exhaust gas generated from a metallurgical furnace.

本発明の冷却方法における上記吸熱化学反応は、還元剤を水蒸気で改質する水蒸気改質反応であり、上記水蒸気として排ガスダクトの蒸気管から発生した水蒸気を用いることを特徴とする。   The endothermic chemical reaction in the cooling method of the present invention is a steam reforming reaction in which a reducing agent is reformed with steam, and steam generated from a steam pipe of an exhaust gas duct is used as the steam.

また、本発明の冷却方法における上記吸熱化学反応は、還元剤を炭酸ガスで改質する炭酸ガス改質反応であり、上記炭酸ガスとして冶金炉から発生する排ガス中の炭酸ガスを用いることを特徴とする。   Further, the endothermic chemical reaction in the cooling method of the present invention is a carbon dioxide reforming reaction in which a reducing agent is reformed with carbon dioxide, and carbon dioxide in exhaust gas generated from a metallurgical furnace is used as the carbon dioxide. And

また、本発明の冷却方法は、上記熱交換チューブとして、転炉排ガス処理設備に設けられた接触ボイラーを用いることを特徴とする。   The cooling method of the present invention is characterized in that a contact boiler provided in a converter exhaust gas treatment facility is used as the heat exchange tube.

（１）本発明によれば、冶金炉から排出される高温の排ガスを熱源として、排ガスダクト内に設置された熱交換チューブ内で還元剤に吸熱化学反応させて、その反応生成物の増熱を図ることによって、冶金炉の操業条件に左右されることなく、高温排ガスの顕熱を間接的に効率的に回収すると共に、上記高温排ガスを効率よく冷却することができる。
（２）また、本発明によれば、上記吸熱化学反応として、還元剤を水蒸気で改質する水蒸気改質反応、還元剤を炭酸ガスで改質する炭酸ガス改質反応および還元剤を熱分解する熱分解反応のいずれか１以上の反応を用いること、および、上記吸熱化学反応を固定床触媒の存在下において行わせること、さらに、上記固定床触蝶として転炉ダストを主成分とする成型物を用いることによって、より効率的に排ガスからの顕熱回収および排ガスの冷却を行うことができる。
（３）また、本発明によれば、還元剤の水蒸気改質反応に用いる水蒸気として、冶金炉に設置された排ガスダクトの蒸発管から発生した水蒸気を用いる、および／または、還元剤の炭酸ガス改質反応に用いる炭酸ガスとして、冶金炉から排出される排ガス中の炭酸ガスを用いることによって、より効率的に排ガスからの顕熱回収および排ガスの冷却を行うことができる。
（４）さらに、本発明では、上記吸熱化学反応に用いる還元剤として、天然ガス、液化石油ガス、メタン、エタン、軽質ナフサ、ラフイネート、メタノール、エタノールなどの化石資源系化合物の他、バイオエタノール、バイオディーゼルあるいはパーム油などの植物性油脂類などの非化石資源系有機化合物も用いることができるので、排ガスからの顕熱回収および排ガスの冷却を低コストで行うことができる。 (1) According to the present invention, the high temperature exhaust gas discharged from the metallurgical furnace is used as a heat source, and the reducing product is subjected to an endothermic chemical reaction in a heat exchange tube installed in the exhaust gas duct to increase the heat of the reaction product. As a result, the sensible heat of the high-temperature exhaust gas can be efficiently recovered indirectly and the high-temperature exhaust gas can be efficiently cooled without being influenced by the operating conditions of the metallurgical furnace.
(2) Further, according to the present invention, as the endothermic chemical reaction, a steam reforming reaction in which the reducing agent is reformed with steam, a carbon dioxide reforming reaction in which the reducing agent is reformed with carbon dioxide, and a reducing agent is thermally decomposed. Using any one or more of the pyrolysis reactions to be performed, and allowing the endothermic chemical reaction to be performed in the presence of a fixed bed catalyst, and further forming a converter dust as a main component as the fixed bed butterfly By using a thing, sensible heat recovery from exhaust gas and cooling of exhaust gas can be performed more efficiently.
(3) Further, according to the present invention, the steam generated from the evaporation pipe of the exhaust gas duct installed in the metallurgical furnace is used as the steam used for the steam reforming reaction of the reducing agent, and / or the carbon dioxide gas of the reducing agent By using carbon dioxide in the exhaust gas discharged from the metallurgical furnace as the carbon dioxide used for the reforming reaction, sensible heat recovery from the exhaust gas and cooling of the exhaust gas can be performed more efficiently.
(4) Furthermore, in the present invention, as a reducing agent used in the endothermic chemical reaction, bioethanol, natural gas, liquefied petroleum gas, methane, ethane, light naphtha, raffinate, methanol, ethanol, bioethanol, Since non-fossil resource-based organic compounds such as vegetable oils such as biodiesel or palm oil can be used, sensible heat recovery from exhaust gas and cooling of exhaust gas can be performed at low cost.

熱交換チューブを排ガスの流れる方向に対して垂直な方向に配設した本発明例を示した模式図である。It is the schematic diagram which showed the example of this invention which has arrange | positioned the heat exchange tube in the direction perpendicular | vertical with respect to the direction through which waste gas flows. 熱交換チューブを排ガスの流れる方向に対して平行な方向に配設した本発明例を示した模式図である。It is the schematic diagram which showed the example of this invention which has arrange | positioned the heat exchange tube in the direction parallel to the direction through which waste gas flows. メンブレンウォールから発生した水蒸気を、水蒸気改質反応の改質剤として用いる本発明例を示した模式図である。It is the schematic diagram which showed the example of this invention which uses the water vapor | steam generate | occur | produced from the membrane wall as a modifier of water vapor | steam reforming reaction. 冶金炉から発生した排出ガス中の炭酸ガスを、炭酸ガス改質反応の改質剤として用いる本発明例を示した模式図である。It is the schematic diagram which showed the example of this invention which uses the carbon dioxide in the exhaust gas generated from the metallurgical furnace as a modifier of a carbon dioxide reforming reaction.

本発明は、冶金炉から排出される８００℃以上、好ましくは１０００℃以上の高温の排ガスを熱源として、冶金炉に備えられた排ガスダクト内に設置された熱交換チューブ内で還元剤に吸熱化学反応させ、その反応生成物を増熱することによって、冶金炉の操業条件に左右されることなく、冶金炉発生排ガスから顕熱を効率的に回収する方法を提案するものである。   The present invention uses an exhaust gas having a high temperature of 800 ° C. or higher, preferably 1000 ° C. or higher discharged from a metallurgical furnace as a heat source, and the endothermic chemistry of the reducing agent in a heat exchange tube installed in an exhaust gas duct provided in the metallurgical furnace. The present invention proposes a method for efficiently recovering sensible heat from the exhaust gas generated in the metallurgical furnace without being influenced by the operating conditions of the metallurgical furnace by reacting and increasing the temperature of the reaction product.

転炉や溶融還元炉のような冶金炉は、回分式（バッチ式）プロセスであるため、排ガスの発生は間歇的であるばかりでなく、排ガスの成分組成や温度、流量が時間とともに大きく変動するのが特徴である。そのため、排ガス設備内で直接的に改質反応を行う従来の顕熱回収方法では、冶金炉の操業条件に起因した排ガス諸特性の変動によって、吸熱反応効率が大きく左右され、自由度に乏しいという欠点がある。   Since metallurgical furnaces such as converters and smelting reduction furnaces are batch-type processes, the generation of exhaust gas is not only intermittent, but the composition, temperature, and flow rate of exhaust gas greatly vary with time. Is the feature. Therefore, in the conventional sensible heat recovery method that directly performs the reforming reaction in the exhaust gas facility, the endothermic reaction efficiency is greatly influenced by the fluctuations in exhaust gas characteristics caused by the operating conditions of the metallurgical furnace, and the degree of freedom is poor. There are drawbacks.

また、転炉ＯＧ設備（転炉排ガス処理設備；Ｏｘｙｇｅｎ Ｃｏｎｖｅｒｔｅｒ Ｇａｓ Ｒｅｃｏｖｅｒｙ Ｓｙｓｔｅｍ）では、転炉排ガスの流量変動による転炉や排ガスダクト内の圧力変動を緩衝するために、炉頂部と排ガスダクトとの間に隙間を設けていることが多く、その隙間から排ガスダクト内に周囲の空気（酸素）が取り込まれる。その結果、吸熱反応させる還元剤（例えば、（１）式のＣＨ４）が燃焼してしまったり、爆発を起こしたりするおそれがある。 Moreover, in the converter OG equipment (converter exhaust gas treatment equipment; Oxygen Converter Gas Recovery System), in order to buffer the pressure fluctuation in the converter and the exhaust gas duct due to the flow fluctuation of the converter exhaust gas, In many cases, a gap is provided between them, and ambient air (oxygen) is taken into the exhaust gas duct from the gap. As a result, the reducing agent (for example, CH 4 of the formula (1)) that undergoes endothermic reaction may burn or explode.

そこで、上記のような冶金炉の操業条件の変動や転炉ＯＧ設備等の構造に起因した悪影響を受けることなく顕熱を効率よく回収するには、排ガスダクト内に設置した熱交換チューブ内で吸熱反応を行わせて間接的に顕熱を回収する方法（以下、「間接法」と称する）が有効であると考えられる。   Therefore, in order to efficiently recover sensible heat without being adversely affected by fluctuations in the operating conditions of the metallurgical furnace as described above or the structure of the converter OG equipment, etc., in a heat exchange tube installed in the exhaust gas duct A method of recovering sensible heat indirectly by causing an endothermic reaction (hereinafter referred to as “indirect method”) is considered effective.

ここで、間接法で顕熱回収に用いる熱交換チューブとしては、間接法が適用できればどのようなものでもよく、例えば、内径が１０〜２００ｍｍφ程度で、長さが１〜２０ｍ程度のステンレス等の金属製チューブからなるものを多数本連結したものが一般的に用いられているが、特に制限はない。チューブの形状は、上記のような直菅を、Ｕ字型の短管で連結した構造とするのが一般的であるが、コイル状など他の形状であってもよい。また、熱伝導を高めるため、チューブ外表面にフィン等を設けたものでもよい。   Here, the heat exchange tube used for the sensible heat recovery in the indirect method may be any tube as long as the indirect method can be applied, such as stainless steel having an inner diameter of about 10 to 200 mmφ and a length of about 1 to 20 m. A connection of many metal tubes is generally used, but there is no particular limitation. The shape of the tube is generally a structure in which the above-described straight rods are connected by a U-shaped short tube, but other shapes such as a coil shape may be used. Moreover, in order to improve heat conduction, what provided the fin etc. in the tube outer surface may be used.

また、転炉ＯＧ設備では、排ガスダクトの輻射部内に、接触ボイラーと呼ばれる水蒸気（スチーム）を発生させる熱交換チューブが配設されていることが多いが、この熱交換チューブを用いて間接法を実施してもよい。この場合、間接法を実施する熱交換チューブから水蒸気を得ることはできないが、接触ボイラーから発生する水蒸気量は、転炉ＯＧ設備全体で発生する水蒸気量の２０〜３０％程度でしかないため、水蒸気需給バランスを崩すほどのことはない。また、間接法によって、水蒸気よりも利用価値の高い可燃性ガスが得られるので、経済的でもある。   Moreover, in converter OG equipment, a heat exchange tube that generates water vapor (steam) called a contact boiler is often disposed in the radiant part of the exhaust gas duct. You may implement. In this case, water vapor cannot be obtained from the heat exchange tube that performs the indirect method, but the amount of water vapor generated from the contact boiler is only about 20 to 30% of the amount of water vapor generated in the entire converter OG facility. There is nothing to break the balance of water vapor supply and demand. In addition, the indirect method is also economical because a combustible gas having a higher utility value than water vapor can be obtained.

なお、熱交換チューブの設置向きは、図１のように、排ガスの流れに対して垂直となる向きであっても、図２のように、排ガスの流れと平行となる向きであってもよい。   The installation direction of the heat exchange tube may be a direction perpendicular to the flow of exhaust gas as shown in FIG. 1 or a direction parallel to the flow of exhaust gas as shown in FIG. .

次に、本発明の顕熱回収方法で用いる吸熱化学反応は、還元剤を水蒸気で改質する水蒸気改質反応、還元剤を炭酸ガスで改質する炭酸ガス改質反応および還元剤を熱分解する熱分解反応のいずれか１以上の反応を用いることができる。これらの反応は、何れも大きな吸熱反応であり、排ガスの顕熱を潜熱として吸収し、生成するガスを増熱することができる。   Next, the endothermic chemical reaction used in the sensible heat recovery method of the present invention includes a steam reforming reaction in which the reducing agent is reformed with steam, a carbon dioxide reforming reaction in which the reducing agent is reformed with carbon dioxide, and a thermal decomposition of the reducing agent. Any one or more of the pyrolysis reactions can be used. These reactions are all endothermic reactions, and can absorb the sensible heat of the exhaust gas as latent heat and increase the temperature of the generated gas.

上記吸熱化学反応のうち、水蒸気改質反応は、熱伝導率が高いことから好ましく用いることができる。また、炭酸ガス改質反応も増熱効果が高く、好ましく用いることができる。また、熱分解反応は、炭化水素を還元剤に用いる場合、煤が生成し易く熱伝導が悪化するため用いることには難があるが、メタノールのように分子内のＣとＯの原子比が１：１の還元剤であれば、ＣＯとＨ２を発生する吸熱化学反応となり、煤生成を伴わずに熱分解させることができる。 Among the endothermic chemical reactions, the steam reforming reaction can be preferably used because of its high thermal conductivity. Further, the carbon dioxide gas reforming reaction has a high heat increasing effect and can be preferably used. In addition, when a hydrocarbon is used as a reducing agent, the pyrolysis reaction is difficult to use because it tends to generate soot and deteriorates the heat conduction, but the atomic ratio of C and O in the molecule is similar to that of methanol. If it is a 1: 1 reducing agent, it becomes an endothermic chemical reaction which generates CO and H 2 and can be thermally decomposed without soot formation.

ここで、熱分解反応の場合、熱交換チューブに供給した還元剤自身が分解するため、還元剤は、酸化還元反応に関与していないことになる。しかしながら、炭酸ガスや水蒸気が共存すれば、並行して逆シフト反応やシフト反応も進行するため、炭酸ガスや水蒸気が還元されることとなる。例えば、メタノールの熱分解を吸熱化学反応とする場合であって、炭酸ガスがメタノールの１０容積％共存する場合、下記式の総括反応に示すように、炭酸ガスは一酸化炭素に還元されており、メタノールを還元剤と見做すことができる。
記
（メタノール熱分解反応）ＣＨ３ＯＨ → ＣＯ＋２Ｈ２
（逆シフト反応）２Ｈ２＋０．１ＣＯ２ → ０．１ＣＯ＋１．９Ｈ２＋０．１Ｈ２Ｏ
（総括反応）ＣＨ３ＯＨ＋０．１ＣＯ２ → １．１ＣＯ＋１．９Ｈ２＋０．１Ｈ２Ｏ Here, in the case of a thermal decomposition reaction, since the reducing agent itself supplied to the heat exchange tube is decomposed, the reducing agent is not involved in the oxidation-reduction reaction. However, if carbon dioxide gas and water vapor coexist, reverse shift reaction and shift reaction also proceed in parallel, so that carbon dioxide gas and water vapor are reduced. For example, when the thermal decomposition of methanol is an endothermic chemical reaction, and carbon dioxide gas coexists with 10% by volume of methanol, the carbon dioxide gas is reduced to carbon monoxide as shown in the general reaction of the following formula. Methanol can be regarded as a reducing agent.
(Methanol thermal decomposition reaction) CH 3 OH → CO + 2H 2
(Reverse shift reaction) 2H 2 + 0.1CO 2 → 0.1CO + 1.9H 2 + 0.1H 2 O
(Overall reaction) CH 3 OH + 0.1CO 2 → 1.1CO + 1.9H 2 + 0.1H 2 O

また、例えば、同じくメタノールの熱分解であって、水蒸気がメタノールの１０容積％共存する場合、下式の総括反応に示すように、水蒸気は水素に還元されており、メタノールを還元剤と見做すこともできる。
記
（メタノール熱分解反応）ＣＨ３ＯＨ → ＣＯ＋２Ｈ２
（シフト反応）ＣＯ＋０．１Ｈ２Ｏ → ０．９ＣＯ＋０．１ＣＯ２＋０．１Ｈ２
（総括反応）ＣＨ３ＯＨ＋０．１Ｈ２Ｏ → ０．９ＣＯ＋２．１Ｈ２＋０．１ＣＯ２
なお、上記逆シフトやシフト反応では、簡単のために反応が１００％右辺に進むものとして表したが、実際には温度やガス組成から求まる平衡組成になることは自明である。 Also, for example, in the case of the thermal decomposition of methanol, when water vapor coexists with 10% by volume of methanol, the water vapor is reduced to hydrogen as shown in the general reaction of the following formula, and methanol is regarded as a reducing agent. You can also
(Methanol thermal decomposition reaction) CH 3 OH → CO + 2H 2
(Shift reaction) CO + 0.1H 2 O → 0.9CO + 0.1CO 2 + 0.1H 2
(Overall reaction) CH 3 OH + 0.1H 2 O → 0.9CO + 2.1H 2 + 0.1CO 2
In the reverse shift or shift reaction, for the sake of simplicity, the reaction is shown as proceeding to the right side of 100%. However, it is obvious that the equilibrium composition is actually obtained from the temperature and gas composition.

また、上記吸熱化学反応は、単独で用いても、組み合わせて用いてもよく、たとえば、水蒸気改質反応、炭酸ガス改質反応および熱分解反応をそれぞれ単独で用いたり、あるいは、水蒸気改質反応と炭酸ガス改質反応、水蒸気改質反応と熱分解反応、炭酸ガス改質反応と熱分解反応とを組み合わせて用いたり、さらには、水蒸気改質反応と炭酸ガス改質反応と熱分解反応とを組み合わせて用いてもよい。   The endothermic chemical reaction may be used alone or in combination. For example, a steam reforming reaction, a carbon dioxide reforming reaction and a thermal decomposition reaction may be used alone, or a steam reforming reaction may be used. And carbon dioxide reforming reaction, steam reforming reaction and thermal decomposition reaction, carbon dioxide reforming reaction and thermal decomposition reaction in combination, or steam reforming reaction, carbon dioxide reforming reaction and thermal decomposition reaction, May be used in combination.

次に、本発明で用いられる上記吸熱化学反応の具体例を以下に示す。なお、括弧内の数字は、原料および生成物の低位燃焼熱である。
（ｉ）メタン水蒸気改質反応
ＣＨ４＋Ｈ２Ｏ（１９２ｋｃａｌ）→ＣＯ＋３Ｈ２（２４１ｋｃａｌ） ・・・（５）
（ｉｉ）メタン炭酸ガス改質反応
ＣＨ４＋ＣＯ２（１９２ｋｃａｌ）→２ＣＯ＋２Ｈ２（２５０ｋｃａｌ） ・・・（６）
（ｉｉｉ）１，３−プロピレングリコール炭酸ガス改質反応
Ｃ３Ｈ８Ｏ２＋ＣＯ２（４０２ｋｃａｌ）→４ＣＯ＋４Ｈ２（５００ｋｃａｌ）
・・・（７）
（ｉＶ）メタン水蒸気改質反応と炭酸ガス改質反応との組み合わせ
２ＣＨ４＋Ｈ２Ｏ＋ＣＯ２（３８４ｋｃａｌ）→３ＣＯ＋５Ｈ２（４９１ｋｃａｌ）
・・・（８）
（Ｖ）メタノール熱分解反応
ＣＨ３ＯＨ（１６２ｋｃａｌ）→ＣＯ＋２Ｈ２（１８３ｋｃａｌ） ・・・（９） Next, specific examples of the endothermic chemical reaction used in the present invention are shown below. The numbers in parentheses are the lower combustion heat of the raw materials and products.
(I) Methane steam reforming reaction CH 4 + H 2 O (192 kcal) → CO + 3H 2 (241 kcal) (5)
(Ii) Methane carbon dioxide reforming reaction CH 4 + CO 2 (192 kcal) → 2CO + 2H 2 (250 kcal) (6)
(Iii) 1,3-propylene glycol carbon dioxide gas reforming reaction C 3 H 8 O 2 + CO 2 (402 kcal) → 4CO + 4H 2 (500 kcal)
... (7)
(IV) Combination of methane steam reforming reaction and carbon dioxide reforming reaction 2CH 4 + H 2 O + CO 2 (384 kcal) → 3CO + 5H 2 (491 kcal)
... (8)
(V) Methanol thermal decomposition reaction CH 3 OH (162 kcal) → CO + 2H 2 (183 kcal) (9)

なお、ＣＯ，Ｈ２，ＣＯ２およびＨ２Ｏの間には、下記（１０）式で表される逆シフト平衡が存在し、Ｈ２によってＣＯ２がＣＯに還元される。通常、この反応は、平衡まで進むので、吸熱反応である逆シフト反応による増熱分も本発明の効果の一部となる。
（Ｖｉ）逆シフト反応
ＣＯ２＋Ｈ２（５８ｋｃａｌ）→ＣＯ＋Ｈ２Ｏ（６７ｋｃａｌ） ・・・（１０）
さらに、炭酸ガスとメタノールが共存する場合、上記（９）式と（１０）式の反応が進行するため、総括して以下の反応となる。
（Ｖｉｉ）炭酸ガス改質反応とメタノール熱分解反応との組み合わせ
ＣＨ３ＯＨ＋ＣＯ２（１６２ｋｃａｌ）→２ＣＯ＋Ｈ２＋Ｈ２Ｏ（１９３ｋｃａｌ）
・・・（１１）
なお、上記（１１）式では、Ｈ２Ｏが生成するため、メタノールの加水分解反応が進行する可能性があるが、加水分解反応は発熱反応であるため、本発明のような高温条件下では、加水分解反応は実質的に無視できる程度である。 Note that a reverse shift equilibrium represented by the following formula (10) exists between CO, H 2 , CO 2, and H 2 O, and CO 2 is reduced to CO by H 2 . Normally, this reaction proceeds to equilibrium, and therefore the heat increase due to the reverse shift reaction, which is an endothermic reaction, is part of the effect of the present invention.
(Vi) Reverse shift reaction CO 2 + H 2 (58 kcal) → CO + H 2 O (67 kcal) (10)
Further, when carbon dioxide gas and methanol coexist, the reactions of the above formulas (9) and (10) proceed, so the following reactions are summarized.
(Vii) Combination of carbon dioxide reforming reaction and methanol thermal decomposition reaction CH 3 OH + CO 2 (162 kcal) → 2CO + H 2 + H 2 O (193 kcal)
(11)
In the above formula (11), since H 2 O is generated, the hydrolysis reaction of methanol may proceed. However, since the hydrolysis reaction is an exothermic reaction, The hydrolysis reaction is virtually negligible.

次に、上記吸熱化学反応に用いる還元剤および改質剤について説明する。
吸熱化学反応に用いる還元剤としては、天然ガスや液化石油ガス、メタン、エタン、軽質ナフサ、ラフイネート、メタノール、エタノールなどの化石資源系化合物のほか、バイオエタノールやバイオディーゼル、パーム油などの植物性油脂類などの非化石資源系有機化合物を用いることができる。
これらの内、天然ガス、液化石油ガス、軽質ナフサ、メタノールは、安価で大量に入手できる点で好ましい。また、バイオエタノールなどのカーボンニュートラルな非化石資源系有機化合物を還元剤に用いる場合には、炭酸ガスの排出量削減効果が大きく、地球環境保護の点からは好ましい。また、廃パーム油など使用後の油脂類を還元剤に用いることは、排ガスの顕熱回収および冷却を低コストに実現できる点で好ましい。 Next, the reducing agent and modifier used for the endothermic chemical reaction will be described.
Reducing agents used in endothermic chemical reactions include natural gas, liquefied petroleum gas, methane, ethane, light naphtha, raffinate, methanol, ethanol, and other fossil resource compounds, and bioethanol, biodiesel, palm oil, and other plant Non-fossil resource-based organic compounds such as fats and oils can be used.
Of these, natural gas, liquefied petroleum gas, light naphtha, and methanol are preferable because they are inexpensive and can be obtained in large quantities. In addition, when a carbon neutral non-fossil resource-based organic compound such as bioethanol is used as the reducing agent, the carbon dioxide emission reduction effect is large, which is preferable from the viewpoint of protecting the global environment. Moreover, it is preferable to use oils and fats after use, such as waste palm oil, as a reducing agent because sensible heat recovery and cooling of exhaust gas can be realized at low cost.

なお、還元剤は、熱分解反応に用いる分子内のＣとＯの原子比が１：１の還元剤を除き、熱分解による煤生成を防止するため、室温〜３００℃の温度範囲で、好ましくは室温〜２００℃の温度範囲で後述する改質剤と接触させるのが好ましい。   The reducing agent is preferably used in a temperature range of room temperature to 300 ° C. in order to prevent soot formation due to thermal decomposition, except for the reducing agent having an atomic ratio of C and O in the molecule of 1: 1 used for the thermal decomposition reaction. Is preferably brought into contact with the modifying agent described later in the temperature range of room temperature to 200 ° C.

次に、上記吸熱化学反応に用いることのできる改質剤としては、水蒸気および／または炭酸ガスが挙げられる。
このうち、水蒸気改質反応の改質剤として水蒸気を用いる場合には、熱交換チューブ内に水（液体）の状態で供給し、水蒸気を発生させてもよいが、水の蒸発潜熱は大きいので、水蒸気の状態で供給するほうが熱効率の点からは好ましい。水蒸気の圧力は、高いほど熱効率が高くなるが、高圧水蒸気は、発電などに用いることのできる価値の高いものなので、圧力が数百ｋＰａ〜１ＭＰａ程度の低圧水蒸気を供給する方が、工場全体のエネルギー効率を向上する上では好ましい。 Next, examples of the modifier that can be used for the endothermic chemical reaction include water vapor and / or carbon dioxide.
Of these, when steam is used as a modifier for the steam reforming reaction, water (liquid) may be supplied into the heat exchange tube to generate steam, but the water has a large latent heat of vaporization. From the viewpoint of thermal efficiency, it is preferable to supply in the state of steam. The higher the steam pressure, the higher the thermal efficiency. However, high-pressure steam has a high value that can be used for power generation and so on. It is preferable for improving energy efficiency.

また、水蒸気改質反応の改質剤として水蒸気を用いる場合には、冶金炉の排ガスダクト内に設置された蒸気管から発生した水蒸気を改質剤の一部として用いることも好ましい。すなわち、冶金炉が、蒸発管から構成された排ガスダクト壁を備えている場合、上記蒸発管で発生した水蒸気を改質剤の一つとして熱交換チューブに供給して水蒸気改質反応を行わせてもよい。   In addition, when steam is used as a modifier for the steam reforming reaction, it is also preferable to use steam generated from a steam pipe installed in the exhaust gas duct of the metallurgical furnace as part of the modifier. That is, when the metallurgical furnace has an exhaust gas duct wall composed of an evaporation pipe, the steam generated in the evaporation pipe is supplied as one of the modifiers to the heat exchange tube to perform the steam reforming reaction. May be.

ここで、上記蒸発管から構成された排ガスダクト壁とは、ボイラーや焼却炉などに一般的に用いられている「メンブレンウォール」のことであって、ダクト壁の冷却と水蒸気発生による熱回収を行う排ガス設備の一つである。このメンブレンウォールは、転炉排ガスダクトなどで採用されていることが多い。そこで、このメンブレンウォールで発生した水蒸気を改質剤の一つとして用いることによって、他のプロセスで水蒸気を発生させたり、輸送したりする必要がなくなるので、熱効率をより高めることができる。なお、転炉ＯＧ設備の場合、メンブレンウォールから発生する水蒸気量は、転炉ＯＧ設備全体から発生する水蒸気量の７０〜８０％にも達するため、間接法で必要とする水蒸気にその一部を供給することに何ら問題はなく、例えば、図３に示すように、メンブレンウォールから発生する水蒸気の一部を、制御弁を介して必要量を供給するようにするのが好ましい。   Here, the exhaust gas duct wall composed of the above-mentioned evaporation pipe is a “membrane wall” generally used in boilers, incinerators, etc., and is used for cooling the duct wall and recovering heat by generating water vapor. It is one of the exhaust gas equipment to be performed. This membrane wall is often used in converter exhaust gas ducts and the like. Therefore, by using the water vapor generated in the membrane wall as one of the modifiers, it is not necessary to generate or transport the water vapor in another process, so that the thermal efficiency can be further improved. In the case of the converter OG facility, the amount of water vapor generated from the membrane wall reaches 70 to 80% of the amount of water vapor generated from the entire converter OG facility. There is no problem in the supply, and for example, as shown in FIG. 3, it is preferable to supply a necessary amount of a part of the water vapor generated from the membrane wall via the control valve.

また、本発明の顕熱回収方法で、炭酸ガス改質反応に用いる場合の炭酸ガスとしては、液化炭酸ガスなどの工業用高純度炭酸ガスを用いてもよいが、図４に示したように、冶金炉から発生する排ガス中の炭酸ガスを改質剤の一部として用いてもよい。すなわち、冶金炉から排出される排ガスには、通常、５〜３０容積％程度のＣＯ２が含まれるため、この排ガスを改質剤として利用することができる。排ガス中の他の成分は、一般的には、ＣＯが１０〜７０容積％、Ｎ２が１０〜５０容積％、Ｈ２が１〜１０容積％程度であり、その他に飽和水蒸気が含まれる。この水蒸気は、水蒸気改質反応の改質剤としても作用することは明らかであるが、水蒸気以外の他の共存ガスは、吸熱化学反応に何ら影響しないので、排ガスを処理することなく、そのまま改質剤として利用することができる。この場合、排ガスダクトで回収した転炉排ガスは既に冷却されていることから、集塵機以降のダクトから、あるいは、排ガスを一時的に貯留するガスホルダーからそのまま熱交換チューブに供給することができる。また、回収された排ガスの温度は、一般的に、５０〜１００℃程度であるが、後述するように、熱交換チューブで予熱することができるため、特別な予熱設備を設置する必要はない。 In addition, as the carbon dioxide gas used in the carbon dioxide reforming reaction in the sensible heat recovery method of the present invention, industrial high-purity carbon dioxide gas such as liquefied carbon dioxide gas may be used, as shown in FIG. Carbon dioxide gas in the exhaust gas generated from the metallurgical furnace may be used as part of the modifier. That is, since the exhaust gas discharged from the metallurgical furnace usually contains about 5 to 30% by volume of CO 2 , this exhaust gas can be used as a modifier. Other components in the exhaust gas is generally, CO 10-70 volume%, N 2 10 to 50% by volume, H 2 is about 1 to 10 volume%, and other saturated steam. It is clear that this steam also acts as a modifier for the steam reforming reaction, but other coexisting gases other than steam do not affect the endothermic chemical reaction at all, so the exhaust gas is not treated and it is modified as it is. It can be used as a quality agent. In this case, since the converter exhaust gas recovered by the exhaust gas duct has already been cooled, it can be directly supplied to the heat exchange tube from the duct after the dust collector or from the gas holder that temporarily stores the exhaust gas. Moreover, although the temperature of the collect | recovered exhaust gas is generally about 50-100 degreeC, since it can preheat with a heat exchange tube so that it may mention later, it is not necessary to install special preheating equipment.

なお、水蒸気や炭酸ガスなどの改質剤は、熱交換チューブ内で予熱後、還元剤と反応させるようにすれば、反応効率を高めることができるので好ましい。予熱温度は、１００〜６００℃程度が好ましく、１５０〜５００℃程度であればより好ましい。この点から、還元剤の添加位置は、熱交換チューブ内の流れ方向で、改質剤の添加位置よりも下流側とすれば、改質剤の予熱ゾーンを作ることができるので好ましい。   It should be noted that a modifier such as water vapor or carbon dioxide is preferably reacted with the reducing agent after preheating in the heat exchange tube, since the reaction efficiency can be increased. The preheating temperature is preferably about 100 to 600 ° C, more preferably about 150 to 500 ° C. From this point, it is preferable that the reducing agent addition position be downstream of the modifying agent addition position in the flow direction in the heat exchange tube, because a preheating zone for the modifying agent can be formed.

また、改質剤として水蒸気と炭酸ガスを複合供給し、２つの改質反応を同時に行わせる場合には、改質剤の供給位置よりも上流側にミキサーなどを設置して、水蒸気と炭酸ガスを混合してから熱交換チューブに供給するのが好ましい。   In the case where steam and carbon dioxide gas are supplied together as a modifier and two reforming reactions are performed simultaneously, a mixer or the like is installed upstream from the supply position of the modifier, and steam and carbon dioxide gas are installed. It is preferable to supply to the heat exchange tube after mixing.

なお、本発明の顕熱回収方法における吸熱化学反応は、触蝶を使用しない熱反応として行わせることもできるが、熱交換チューブ内に触媒を充填し、固定床触媒の存在下で、触媒反応として行わせることが好ましい。触媒反応とすることの利点は、反応速度が速くなり、還元剤の転化率を高くすることができることにある。触媒としては、Ｎｉ系やＦｅ系などの卑金属を担持した触媒の他、Ｐｔ系やＣｕ系などの貴金属を担持した触媒などを例示することができるが、特に限定されるものではない。触媒の形状は、熱交換チューブ内に充填するため、圧力損失の低い形状であることが好ましく、具体的には、粒状やペレット状、リング状、車輪状、ガトリングガン状などの形状の成型触媒やハニカム形状の触媒を挙げることができる。   The endothermic chemical reaction in the sensible heat recovery method of the present invention can be carried out as a thermal reaction without using a butterfly, but the catalyst reaction is carried out in the presence of a fixed bed catalyst by filling a catalyst in a heat exchange tube. It is preferable to carry out as follows. The advantage of the catalytic reaction is that the reaction rate is increased and the conversion rate of the reducing agent can be increased. Examples of the catalyst include, but are not limited to, a catalyst supporting a noble metal such as a Pt-based material or a Cu-based material in addition to a catalyst supporting a base metal such as a Ni-based material or Fe-based material. The shape of the catalyst is preferably a shape having a low pressure loss because it is filled in the heat exchange tube. Specifically, the catalyst has a shape such as a granular shape, a pellet shape, a ring shape, a wheel shape, or a gatling gun shape. And a honeycomb-shaped catalyst.

また、本発明では、転炉ダストを含む成型物を固定床触媒として用いることが好ましい。これは転炉ダストを主触媒成分とする触媒を担持した成型触媒である。転炉ダストは、微細な鉄粒子が主成分であり、吸熱反応、特に改質反応の主触媒成分として有効である。転炉ダストは、触媒担体に対する触媒成分の質量比である担持率で表して、５〜２０ｍａｓｓ％程度が適当であるが、これに限定されるものではない。また、ＮｉやＣｕなどの助触媒成分を添加してもよい。   Moreover, in this invention, it is preferable to use the molding containing a converter dust as a fixed bed catalyst. This is a molded catalyst carrying a catalyst having converter dust as a main catalyst component. Converter dust is mainly composed of fine iron particles and is effective as a main catalyst component for endothermic reactions, particularly reforming reactions. The converter dust is represented by a loading ratio, which is a mass ratio of the catalyst component to the catalyst carrier, and is preferably about 5 to 20 mass%, but is not limited thereto. Further, a promoter component such as Ni or Cu may be added.

また、触媒を用いる場合は、熱交換チューブ内の還元剤添加位置付近から触媒が充填されていれば良く、改質剤の予熱ゾーンには、触媒を充填する必要はない。しかし、予熱効率を高めることと、ガスとの混合をより高めるために、予熱ゾーンにセラミックボールなどを充填しておいてもよい。また、触媒を用いる場合であって、還元剤や改質剤にダストなどが含まれている場合は、触媒層の上部にアルミナボールなどを充填し、触媒のガード層を設けることが好ましい。   When a catalyst is used, it is sufficient that the catalyst is filled from the vicinity of the reducing agent addition position in the heat exchange tube, and it is not necessary to fill the catalyst in the preheating zone of the modifier. However, in order to increase the preheating efficiency and the mixing with the gas, the preheating zone may be filled with ceramic balls or the like. When a catalyst is used and the reducing agent or modifier contains dust, it is preferable to fill the upper part of the catalyst layer with alumina balls or the like and provide a guard layer for the catalyst.

次に、本発明における吸熱化学反応条件について説明する。
本発明で用いる吸熱化学反応は、分子数が増加する反応であるので、高圧で反応させるのは好ましくなく、微加圧から減圧下で反応させるのが好ましいが、ガス漏洩の検知の容易さなどから、０．５ＭＰａ以下の微加圧から常圧（約０．１ＭＰａ）程度の圧力下で反応させるのが好ましい。 Next, endothermic chemical reaction conditions in the present invention will be described.
Since the endothermic chemical reaction used in the present invention is a reaction in which the number of molecules increases, it is not preferable to carry out the reaction at a high pressure, and it is preferable to carry out the reaction from a slight pressure to a reduced pressure. Therefore, the reaction is preferably performed under a pressure of about 0.5 MPa or less to a normal pressure (about 0.1 MPa).

また、吸熱化学反応の反応温度は、用いる反応の種類や触媒の有無によって、最適温度域が異なる。例えば、天然ガスの水蒸気改質では、４００〜１５００℃程度の温度が好ましく、６００〜１３００℃程度の温度がより好ましい。また、天然ガスの炭酸ガス改質では、６００〜１８００℃程度の温度が好ましく、７００〜１６００℃程度の温度がより好ましい。また、熱分解反応では、４００〜１４００℃程度の温度が好ましく、５００〜１２００℃程度の温度がより好ましい。なお、一般に、還元剤の炭素鎖が長くなると、最適温度域は低くなり、同じ還元剤であれば、炭酸ガス改質よりも水蒸気改質の方が最適温度域は低くなる傾向にある。   The reaction temperature of the endothermic chemical reaction varies depending on the type of reaction used and the presence or absence of a catalyst. For example, in steam reforming of natural gas, a temperature of about 400 to 1500 ° C. is preferable, and a temperature of about 600 to 1300 ° C. is more preferable. In the carbon dioxide gas reforming of natural gas, a temperature of about 600 to 1800 ° C is preferable, and a temperature of about 700 to 1600 ° C is more preferable. In the thermal decomposition reaction, a temperature of about 400 to 1400 ° C is preferable, and a temperature of about 500 to 1200 ° C is more preferable. In general, the longer the carbon chain of the reducing agent, the lower the optimum temperature range. With the same reducing agent, the optimum temperature range tends to be lower in steam reforming than in carbon dioxide reforming.

また、熱交換チューブ内での原料ガス（還元剤、改質剤）の滞留時間は０．０１〜２０秒の範囲が好ましく、０．１〜１５秒であればより好ましく、０．５〜１０秒であればさらに好ましい。滞留時間が０．０１秒以上とすれば、未反応の還元剤が多くなることがなく、顕熱回収率が低下しない。一方、滞留時間が２０秒以下とすると、吸熱反応は十分に進行し、熱交換チューブが長くならないため、設備費が高価にならないばかりでなく、熱交換チューブ内の圧力損失も大きくならないため、改質剤などの反応原料を送風する動力費も高くならないからである。   The residence time of the source gas (reducing agent, modifier) in the heat exchange tube is preferably in the range of 0.01 to 20 seconds, more preferably 0.1 to 15 seconds, and 0.5 to 10 seconds. More preferred is seconds. If the residence time is 0.01 seconds or longer, the amount of unreacted reducing agent will not increase, and the sensible heat recovery rate will not decrease. On the other hand, if the residence time is 20 seconds or less, the endothermic reaction proceeds sufficiently and the heat exchange tube does not become long, so that not only the equipment cost becomes expensive, but also the pressure loss in the heat exchange tube does not become large. This is because the power cost for blowing the reaction raw material such as a quality agent does not increase.

なお、熱交換チューブ内への還元剤や改質剤などの吸熱反応原料の供給は、排ガスの流れる方向に対して併流であっても向流であってもよいが、向流の方が、反応効率が高まるので好ましい。   Note that the supply of the endothermic reaction raw materials such as the reducing agent and the modifier into the heat exchange tube may be cocurrent or countercurrent to the flow direction of the exhaust gas. This is preferable because the reaction efficiency increases.

上記のように、本発明の顕熱回収方法によれば、高温の排ガスを熱源として吸熱化学反応を効率よく行わせることができる。したがって、本発明の顕熱回収方法を行うことにより、高温の排ガスを効率よく冷却することも、また可能である。   As described above, according to the sensible heat recovery method of the present invention, an endothermic chemical reaction can be efficiently performed using high-temperature exhaust gas as a heat source. Therefore, it is also possible to efficiently cool the high-temperature exhaust gas by performing the sensible heat recovery method of the present invention.

転炉ＯＧ設備のボイラーで水蒸気を発生させて顕熱回収を行っている２５０ｔの上吹き転炉において、排ガスダクトの輻射部に設置された接触ボイラーを熱交換チューブとして用いて吸熱化学反応させ、下記発明例１〜５に示した一群の顕熱回収実験を行った。   In a 250 t top blow converter where steam is generated by the boiler of the converter OG equipment and sensible heat recovery is performed, an endothermic chemical reaction is performed using a contact boiler installed in the radiant part of the exhaust gas duct as a heat exchange tube, A group of sensible heat recovery experiments shown in the following Invention Examples 1 to 5 were conducted.

なお、転炉から排出される排ガスは、流量が１３２０００Ｎｍ３／ｈで、ガス組成がＣＯ：５３容積％、ＣＯ２：１５容積％、Ｈ２：９容積％、Ｎ２：２３容積％であった。また、吸熱化学反応を行っていない時の水蒸気発生量は、フード、下部ボイラーおよび上部ボイラーからの合計が９００ｔ／ｈ、接触ボイラーからは３００ｔ／ｈであり、接触ボイラーから発生する水蒸気は全体の２５％であった。また、吸熱化学反応を行っていない時の排ガス温度は、炉頂部付近で約１７００℃、接触ボイラー手前の位置で約９００℃、接触ボイラー直後の位置で約６００℃であった。 The exhaust gas discharged from the converter had a flow rate of 132000 Nm 3 / h and a gas composition of CO: 53% by volume, CO 2 : 15% by volume, H 2 : 9% by volume, and N 2 : 23% by volume. It was. In addition, the amount of water vapor generated when no endothermic chemical reaction is performed is 900 t / h in total from the hood, lower boiler and upper boiler, and 300 t / h from the contact boiler. 25%. Further, the exhaust gas temperature when the endothermic chemical reaction was not performed was about 1700 ° C. near the top of the furnace, about 900 ° C. at a position before the contact boiler, and about 600 ° C. immediately after the contact boiler.

また、熱交換チューブに用いた接触ボイラーの内径は、１００ｍｍφであり、１系列の伝熱面積が７８ｍ２の熱交換器が８系列設置されている（全伝熱面積は６２４ｍ２）。この８系列の熱交換器の全てに、天然ガスなどの還元剤と、水蒸気などの改質剤を同一流量で供給できるように配管や流量調節弁などを設置した。また、実験では、吸熱化学反応による顕熱回収後でも、接触ボイラー直後の排ガス温度が、吸熱化学反応を行っていない時と同様、約６００℃となるように還元剤と改質剤の流量を調節した。
なお、改質剤としての水蒸気は、図３に示すようにメンブレンウォールで構成されているフード、下部ボイラーおよび上部ボイラーから発生する水蒸気を供給するものとした。また、炭酸ガスとしては、液化炭酸ガスを気化器で気化させたものを供給した。また、熱交換チューブ内のガスの流れは、転炉排ガスに対して向流となるように還元剤と改質剤を供給した。反応圧力は常圧とした。 Moreover, the inner diameter of the contact boiler used for the heat exchange tube is 100 mmφ, and eight series of heat exchangers with one series of heat transfer area of 78 m 2 are installed (total heat transfer area is 624 m 2 ). In all of these 8 series heat exchangers, piping, flow control valves and the like were installed so that a reducing agent such as natural gas and a modifier such as water vapor could be supplied at the same flow rate. In addition, in the experiment, the flow rates of the reducing agent and the modifying agent are set so that the exhaust gas temperature immediately after the contact boiler is about 600 ° C. even after the sensible heat recovery by the endothermic chemical reaction, as in the case where the endothermic chemical reaction is not performed. Adjusted.
In addition, the water vapor | steam as a modifier shall supply the water vapor | steam which generate | occur | produces from the hood comprised by the membrane wall, a lower boiler, and an upper boiler as shown in FIG. Further, as the carbon dioxide gas, a gas obtained by vaporizing liquefied carbon dioxide gas with a vaporizer was supplied. Moreover, the reducing agent and the modifier were supplied so that the gas flow in the heat exchange tube was countercurrent to the converter exhaust gas. The reaction pressure was normal pressure.

〔発明例１〕
還元剤として、メタン９０容積％、エタン６容積％、プロパン３容積％、ブタン１容積％の組成からなる天然ガスを、また、改質剤として水蒸気を、図１に示すような排ガスの流れに対して垂直に設置した接触ボイラーに（熱交換チューブ）供給し、無触媒で水蒸気改質反応させて、吸熱化学反応による転炉排ガスの顕熱回収実験を行った。その結果を表１に示したが、８系列の接触ボイラーに供給した還元剤（天然ガス）および改質剤（水蒸気）は、全流量で表してそれぞれ５３００Ｎｍ３／ｈ、６．６ｔ／ｈとし、このときの接触ボイラー直後の排ガス温度は約６００℃とした。 [Invention Example 1]
As a reducing agent, natural gas having a composition of 90% by volume of methane, 6% by volume of ethane, 3% by volume of propane, and 1% by volume of butane and steam as a modifier are used in the exhaust gas flow shown in FIG. On the other hand, a sensible heat recovery experiment of converter exhaust gas by an endothermic chemical reaction was conducted by supplying (heat exchange tube) to a contact boiler installed vertically and causing a steam reforming reaction without a catalyst. The results are shown in Table 1. The reducing agent (natural gas) and the modifying agent (steam) supplied to the 8 series contact boilers are 5300 Nm 3 / h and 6.6 t / h, respectively, expressed in terms of the total flow rate. The exhaust gas temperature immediately after the contact boiler at this time was about 600 ° C.

また、水蒸気改質後に得られた反応生成ガスの温度は約７００℃で、その流量は２３８００Ｎｍ３／ｈであり、分析結果から求めた反応生成ガスの低位燃焼熱は２５９０ｋｃａｌ／Ｎｍ３であった。この結果から、上記吸熱反応によって、単位時間あたり６１．６Ｇｃａｌ／ｈの燃焼熱を持つガスが得られたことになる。一方、還元剤として供給した天然ガスの低位燃焼熱は９６７０ｋｃａｌ／Ｎｍ３であるので、天然ガスとして５１．３Ｇｃａｌ／ｈの燃焼熱を供給したことになる。したがって、本発明例における増熱率は２０．１％であり、この増熱分が、吸熱化学反応による転炉排ガスからの顕熱回収分に相当する。以上の結果から、間接法によっても高温排ガスの顕熱回収が安定して行えることが確認された。 The temperature of the reaction product gas obtained after steam reforming was about 700 ° C., the flow rate was 23800 Nm 3 / h, and the lower combustion heat of the reaction product gas obtained from the analysis results was 2590 kcal / Nm 3 . . From this result, a gas having a combustion heat of 61.6 Gcal / h per unit time was obtained by the endothermic reaction. On the other hand, since the lower combustion heat of the natural gas supplied as the reducing agent is 9670 kcal / Nm 3 , the combustion heat of 51.3 Gcal / h is supplied as the natural gas. Accordingly, the heat increase rate in the present invention example is 20.1%, and this heat increase corresponds to the sensible heat recovery from the converter exhaust gas by the endothermic chemical reaction. From the above results, it was confirmed that sensible heat recovery of high-temperature exhaust gas can be stably performed by the indirect method.

なお、水蒸気改質に使用した水蒸気６．６ｔ／ｈは、フード、下部ボイラーおよび上部ボイラーから発生する水蒸気の０．７％に過ぎず、水蒸気の需給バランスに何ら影響はなかった。また、生成ガス温度は約７００℃であるため、水蒸気を発生させることにより、生成ガスからのさらなる顕熱回収が可能である。   The steam 6.6 t / h used for steam reforming was only 0.7% of the steam generated from the hood, the lower boiler, and the upper boiler, and had no influence on the supply and demand balance of steam. Further, since the generated gas temperature is about 700 ° C., further sensible heat recovery from the generated gas is possible by generating water vapor.

〔発明例２〕
この発明例は、熱交換チューブ内に、市販のＮｉ系改質触媒（ズードケミー触媒（株）製 ＲｅｆｏｒＭａｘ３３０ＬＤＰ；Ｎｉ：１１ｍａｓｓ％含有）を充填し、図２に示すような転炉排ガスの流れと平行となる向きに設置した熱交換チューブを用いた以外は、発明例１と同様にして天然ガスの水蒸気改質反応による顕熱回収実験を行った例であり、結果を表１に併記した。表１から、無触媒である発明例１の場合よりも、天然ガス供給量を多くできるので、増熱率は低下するものの、顕熱回収量を増大できることがわかる。 [Invention Example 2]
In this example of the invention, a commercially available Ni-based reforming catalyst (ReforMax 330LDP manufactured by Zude Chemie Catalysts Co., Ltd .; containing Ni: 11% by mass) is filled in a heat exchange tube and parallel to the flow of the converter exhaust gas as shown in FIG. Except for using the heat exchange tube installed in the orientation, the sensible heat recovery experiment by natural gas steam reforming reaction was conducted in the same manner as in Example 1, and the results are also shown in Table 1. From Table 1, it can be seen that the amount of natural gas supplied can be increased as compared to the case of Invention Example 1 which is non-catalyst, so that the sensible heat recovery amount can be increased although the heat increase rate is decreased.

〔発明例３〕
この発明例は、吸熱化学反応として、無触媒下において天然ガスの炭酸ガス改質反応を行った例であり、改質剤として炭酸ガスを用いた以外は、実施例１と同様にして顕熱回収実験を行った。表１に併記して示したように、水蒸気改質に比べて、反応生成ガスの低位燃焼熱は低いが、還元剤である天然ガスの供給量が少なくても、増熱率を約３０％と高めることができる。 [Invention Example 3]
This example of the invention is an example in which a natural gas carbon dioxide reforming reaction was performed as an endothermic chemical reaction in the absence of a catalyst, and sensible heat was obtained in the same manner as in Example 1 except that carbon dioxide was used as a modifier. A recovery experiment was conducted. As shown together in Table 1, the lower combustion heat of the reaction product gas is lower than that of steam reforming, but the rate of increase in heat is about 30% even if the supply amount of natural gas as a reducing agent is small. And can be enhanced.

〔発明例４〕
この発明例は、改質剤として、水蒸気と炭酸ガスをモル比で１：１に混合したガスを用いた以外は、発明例１と同様にして、無触媒下における天然ガスの水蒸気・炭酸ガス改質反応による顕熱回収実験を行った例である。結果を表１に併記して示したように、発明例１と発明例３の中間的な結果となっており、混合改質剤を用いて複数の吸熱化学反応を組み合わせてもよいことが確認された。 [Invention Example 4]
This invention example is a natural gas water vapor / carbon dioxide gas under non-catalyst in the same manner as the invention example 1 except that a gas in which water vapor and carbon dioxide gas are mixed at a molar ratio of 1: 1 is used as a modifier. This is an example in which a sensible heat recovery experiment by a reforming reaction was conducted. As shown in Table 1, the results are intermediate between Invention Example 1 and Invention Example 3, and it is confirmed that a plurality of endothermic chemical reactions may be combined using a mixed modifier. It was done.

〔発明例５〕
この発明例は、吸熱化学反応として無触媒下におけるメタノールの熱分解反応を選択した例である。還元剤として工業用メタノール（低位燃焼熱５０６０ｋｃａｌ／ｋｇ）を用い、これを気化して供給したこと、および改質剤は供給しなかったこと以外は実施例１と同様にして顕熱回収実験を行った。結果を表１に併記して示したように、熱分解反応によっても顕熱回収が可能なことが確認された。なお、熱分解反応を用いた場合、増熱率は低めであるが、低位燃焼熱の高い反応生成ガスが得られることが特徴である。 [Invention Example 5]
In this example, a thermal decomposition reaction of methanol in the absence of a catalyst is selected as the endothermic chemical reaction. A sensible heat recovery experiment was conducted in the same manner as in Example 1 except that industrial methanol (low combustion heat 5060 kcal / kg) was used as the reducing agent, this was vaporized and supplied, and the modifier was not supplied. went. As the results are shown together in Table 1, it was confirmed that sensible heat recovery was possible even by a thermal decomposition reaction. In addition, when a thermal decomposition reaction is used, although the heat increase rate is low, it is the characteristics that the reaction product gas with a high low combustion heat is obtained.

Figure 2011102658
Figure 2011102658

実施例１と同じ、転炉ＯＧ設備のボイラーで水蒸気を発生させて顕熱回収を行っている２５０ｔの上吹き転炉において、排ガスダクトの輻射部に設置された接触ボイラーを熱交換チューブとして用いて吸熱化学反応させ、下記発明例６〜９に示した一群の顕熱回収実験を行った。   In the 250 t top blow converter where steam is generated by the boiler of the converter OG facility and the sensible heat is recovered as in the first embodiment, the contact boiler installed in the radiant part of the exhaust gas duct is used as the heat exchange tube. A group of sensible heat recovery experiments shown in the following Invention Examples 6 to 9 were conducted.

なお、転炉から排出される排ガスは、流量が１３２０００Ｎｍ３／ｈで、ガス組成がＣＯ：５３容積％、ＣＯ２：１５容積％、Ｈ２：９容積％、Ｎ２：２３容積％であった。また、吸熱反応を行っていない時の水蒸気発生量は、フード、下部ボイラーおよび上部ボイラーからの合計が９００ｔ／ｈ、接触ボイラーからは３００ｔ／ｈであり、接触ボイラーから発生する水蒸気は全体の２５％であった。また、吸熱化学反応を行っていない時の排ガス温度は、炉頂部付近で約１７００℃、接触ボイラー手前の位置で約９００℃、接触ボイラー直後の位置で約６００℃であった。 The exhaust gas discharged from the converter had a flow rate of 132000 Nm 3 / h and a gas composition of CO: 53% by volume, CO 2 : 15% by volume, H 2 : 9% by volume, and N 2 : 23% by volume. It was. In addition, when the endothermic reaction is not performed, the total amount of water vapor generated is 900 t / h from the hood, the lower boiler, and the upper boiler, and 300 t / h from the contact boiler. The total amount of water vapor generated from the contact boiler is 25 %Met. Further, the exhaust gas temperature when the endothermic chemical reaction was not performed was about 1700 ° C. near the top of the furnace, about 900 ° C. at a position before the contact boiler, and about 600 ° C. immediately after the contact boiler.

また、熱交換チューブに用いた接触ボイラーの内径は、１００ｍｍφであり、１系列の伝熱面積が７８ｍ２の熱交換器が８系列設置されている（全伝熱面積は６２４ｍ２）。この８系列の熱交換器の全てに、天然ガスなどの還元剤と、炭酸ガスなどの改質剤を同一流量で供給できるように配管や流量調節弁などを設置した。また、実験では、吸熱化学反応による顕熱回収後でも、接触ボイラー直後の排ガス温度が、吸熱化学反応を行っていない時と同様、約６００℃となるように還元剤と改質剤の流量を調節した。 Moreover, the inner diameter of the contact boiler used for the heat exchange tube is 100 mmφ, and eight series of heat exchangers with one series of heat transfer area of 78 m 2 are installed (total heat transfer area is 624 m 2 ). In all of these 8 series heat exchangers, piping and flow control valves were installed so that reducing agents such as natural gas and modifiers such as carbon dioxide could be supplied at the same flow rate. In addition, in the experiment, the flow rates of the reducing agent and the modifying agent are set so that the exhaust gas temperature immediately after the contact boiler is about 600 ° C. even after the sensible heat recovery by the endothermic chemical reaction, as in the case where the endothermic chemical reaction is not performed. Adjusted.

なお、改質剤としての炭酸ガスは、図４に示すように転炉排ガス中に含まれる炭酸ガスを用いた。転炉排ガスは、転炉ＯＧ設備のフレアとガスホルダーへの分岐点となる三方切替弁の上流側直近に枝分かれの配管と遮断弁、流量調節弁などを設置し、必要流量の排ガスが吸熱化学反応器となる接触ボイラーに供給できるようにした。なお、設置した枝分かれ配管近傍での転炉回収排ガスの温度は約５０℃であった。また、水蒸気は、メンブレンウォールで構成されているフード、下部ボイラーおよび上部ボイラーから発生する水蒸気を供給するものとした。熱交換チューブ内のガスの流れは、転炉排ガスに対して向流となるように還元剤と改質剤を供給した。反応圧力は常圧とした。   The carbon dioxide gas as the modifier was carbon dioxide contained in the converter exhaust gas as shown in FIG. For the converter exhaust gas, a branching pipe, a shut-off valve, a flow control valve, etc. are installed near the upstream side of the three-way switching valve that becomes the branch point to the flare and gas holder of the converter OG equipment. It was made possible to supply to a contact boiler as a reactor. Note that the temperature of the converter recovery exhaust gas in the vicinity of the installed branch pipe was about 50 ° C. In addition, water vapor is supplied from water generated from the hood, the lower boiler, and the upper boiler made of the membrane wall. The reducing agent and the modifier were supplied so that the gas flow in the heat exchange tube was countercurrent to the converter exhaust gas. The reaction pressure was normal pressure.

〔発明例６〕
還元剤として、メタン９０容積％、エタン６容積％、プロパン３容積％、ブタン１容積％の組成からなる天然ガスを、また、改質剤として転炉排ガスのみを、図１に示すような排ガスの流れに対して垂直に設置した接触ボイラー（熱交換チューブ）に供給し、無触媒で炭酸ガス改質反応させて、吸熱化学反応による転炉排ガスの顕熱回収実験を行った。その結果を表２に示したが、８系列の接触ボイラーに供給した還元剤（天然ガス）および転炉排ガスは、全流量で表してそれぞれ１８００Ｎｍ３／ｈおよび１５７００Ｎｍ３／ｈ（ＣＯ２換算で２３５０Ｎｍ３／ｈ）であり、そのときの接触ボイラー直後の排ガス温度は約６００℃であった。 [Invention Example 6]
As a reducing agent, a natural gas having a composition of 90% by volume of methane, 6% by volume of ethane, 3% by volume of propane, and 1% by volume of butane is used. Was supplied to a contact boiler (heat exchange tube) installed perpendicular to the flow of the gas, and carbon dioxide gas reforming reaction was carried out without a catalyst, and a sensible heat recovery experiment of converter exhaust gas by an endothermic chemical reaction was conducted. The results are shown in Table 2, and the reducing agent (natural gas) and converter exhaust gas supplied to the 8 series contact boilers are expressed in terms of total flow rates of 1800 Nm 3 / h and 15700 Nm 3 / h (in terms of CO 2) , respectively. 2350 Nm 3 / h), and the exhaust gas temperature immediately after the contact boiler was about 600 ° C.

また、炭酸ガス改質後に得られた反応生成ガスの温度は約７９０℃で、その流量は２１４００Ｎｍ３／ｈであり、分析結果から求めた生成ガスの低位燃焼熱は２３００ｋｃａｌ／Ｎｍ３であった。この結果から、上記吸熱化学反応によって、単位時間あたりでは４９．２Ｇｃａｌ／ｈの燃焼熱を持つガスが得られたことになる。一方、還元剤として供給した天然ガスの低位燃焼熱は９６７０ｋｃａｌ／Ｎｍ３であるので天然ガスとして１７．４Ｇｃａｌ／ｈの燃焼熱を、また、転炉排ガスの低位燃焼熱は１８３０ｋｃａｌ／Ｎｍ３であるので転炉排ガスとして２８．７Ｇｃａｌ／ｈの燃焼熱を供給したことになり、合計で４６．１Ｇｃａｌ／ｈの燃焼熱を供給したことになる。したがって、本発明例における増熱率は６．７％であり、この増熱分が、吸熱化学反応によって転炉排ガスから回収した顕熱に相当する。また、炭酸ガス改質後の反応生成ガス温度が約７９０℃であることから、この反応生成ガスを用いて水蒸気を発生させることにより、さらなる顕熱回収が可能なことは明らかである。 The temperature of the reaction product gas obtained after carbon dioxide reforming was about 790 ° C., the flow rate was 21400 Nm 3 / h, and the lower combustion heat of the product gas obtained from the analysis results was 2300 kcal / Nm 3 . . From this result, a gas having a combustion heat of 49.2 Gcal / h per unit time was obtained by the endothermic chemical reaction. On the other hand, since the lower combustion heat of natural gas supplied as a reducing agent is 9670 kcal / Nm 3 , combustion heat of 17.4 Gcal / h is obtained as natural gas, and lower combustion heat of converter exhaust gas is 1830 kcal / Nm 3 . Therefore, 28.7 Gcal / h of combustion heat was supplied as the converter exhaust gas, and a total of 46.1 Gcal / h of combustion heat was supplied. Therefore, the heat increase rate in the present invention example is 6.7%, and this heat increase corresponds to the sensible heat recovered from the converter exhaust gas by the endothermic chemical reaction. Moreover, since the reaction product gas temperature after carbon dioxide reforming is about 790 ° C., it is clear that further sensible heat recovery is possible by generating water vapor using this reaction product gas.

〔発明例７〕
この発明例は、改質剤として転炉排ガス中の炭酸ガスに加えて、水蒸気を複合添加した以外は、発明例６と同様にして、天然ガスの炭酸ガス改質反応・水蒸気改質によって顕熱回収を行った例である。結果を表２に併記して示したが、炭酸ガス単独で顕熱回収を行った発明例６よりも増熱率が高くなることが確認された。なお、水蒸気改質に使用した水蒸気は０．９ｔ／ｈであり、転炉ＯＧ設備のフード、下部・上部ボイラーから発生する水蒸気の０．１％に過ぎず、水蒸気の需給バランスに何ら影響はなかった。 [Invention Example 7]
This invention example is manifested by a carbon dioxide gas reforming reaction / steam reforming of natural gas in the same manner as in Invention Example 6 except that steam is added in combination with carbon dioxide in the converter exhaust gas as a modifier. This is an example of heat recovery. The results are shown together in Table 2, and it was confirmed that the heat increase rate was higher than that of Invention Example 6 in which sensible heat recovery was performed using carbon dioxide alone. The steam used for steam reforming is 0.9 t / h, which is only 0.1% of the steam generated from the hood of the converter OG facility and the lower and upper boilers, and has no effect on the supply and demand balance of steam. There wasn't.

〔発明例８〕
この実施例は、熱交換チューブ内に、市販のＮｉ系改質触媒（ズードケミー触媒（株）製 ＲｅｆｏｒＭａｘ３３０ＬＤＰ；Ｎｉ：１１ｍａｓｓ％含有）を充填し、図２に示すような転炉排ガスの流れと平行となる向きに設置した熱交換チューブを用いた以外は、発明例７と同様にして天然ガスの水蒸気改質反応による顕熱回収実験を行った例である。結果を表２に併記したが、無触媒である発明例７の場合よりも、天然ガス供給量を１０％強多く供給できるので、増熱率は低下するものの、回収顕熱量を増大できることがわかる。 [Invention Example 8]
In this example, a commercially available Ni-based reforming catalyst (ReforMax 330LDP manufactured by Zude Chemie Catalysts Co., Ltd .; containing Ni: 11% by mass) is filled in a heat exchange tube and parallel to the flow of the converter exhaust gas as shown in FIG. This is an example of conducting a sensible heat recovery experiment by a steam reforming reaction of natural gas in the same manner as in Invention Example 7 except that a heat exchange tube installed in the direction is used. Although the results are also shown in Table 2, it can be seen that since the natural gas supply amount can be supplied more than 10% more than in the case of the invention example 7 which is non-catalyst, the heat increase rate is decreased, but the recovered sensible heat amount can be increased. .

〔発明例９〕
この実施例は、還元剤（被分解物質）としてメタノール（低位燃焼熱５０６０ｋｃａｌ／ｋｇ）を用いたこと以外は、発明例６と同様にして、転炉排ガスからの顕熱回収実験を行った例である。結果を表２に併記したが、炭酸ガス改質反応以外に熱分解が進行するため、増熱率が５％と低いが、炭酸ガス改質反応と熱分解反応の組み合わせでも、排ガスからの顕熱回収が可能であることが確認された。 [Invention Example 9]
In this example, a sensible heat recovery experiment from converter exhaust gas was conducted in the same manner as Example 6 except that methanol (low combustion heat 5060 kcal / kg) was used as the reducing agent (decomposable substance). It is. The results are also shown in Table 2. Although thermal decomposition proceeds in addition to the carbon dioxide reforming reaction, the rate of increase in heat is as low as 5%. It was confirmed that heat recovery was possible.

Figure 2011102658
Figure 2011102658

本発明は、転炉の排ガスだけでなく、溶融還元炉や電気炉、非鉄精錬で用いられる各種炉などから発生する高温排ガスの顕熱回収技術および上記高温排ガスの冷却技術としても有用である。さらに、実施例の結果からわかるように、本発明によって得られる吸熱化学反応後の反応生成ガスは、Ｈ２／ＣＯ比が０．５〜４程度と広い範囲で変えることができるので、各種化学合成原料としても用いることができる。 The present invention is useful not only for converter exhaust gas but also for sensible heat recovery technology for high-temperature exhaust gas generated from smelting reduction furnaces, electric furnaces, various furnaces used in non-ferrous refining, and cooling technology for the high-temperature exhaust gas. Further, as can be seen from the results of the examples, the reaction product gas after the endothermic chemical reaction obtained by the present invention can be changed in a wide range of H 2 / CO ratio of about 0.5 to 4, so various chemicals can be used. It can also be used as a synthetic raw material.

Claims (11)

冶金炉から排出される高温の排ガスを熱源として、冶金炉の排ガスダクト内に設置された熱交換チューブ内で還元剤を吸熱化学反応させ、その反応生成物を増熱することを特徴とする冶金炉発生排ガスからの顕熱回収方法。 Metallurgical metallurgy characterized in that high-temperature exhaust gas discharged from the metallurgical furnace is used as a heat source, the reducing agent is subjected to an endothermic chemical reaction in a heat exchange tube installed in the exhaust gas duct of the metallurgical furnace, and the reaction product is heated. A method for recovering sensible heat from furnace exhaust gas. 上記吸熱化学反応は、還元剤を水蒸気で改質する水蒸気改質反応、還元剤を炭酸ガスで改質する炭酸ガス改質反応および還元剤を熱分解する熱分解反応のいずれか１以上の反応であることを特徴とする請求項１に記載の冶金炉発生排ガスからの顕熱回収方法。 The endothermic chemical reaction is one or more of a steam reforming reaction in which the reducing agent is reformed with steam, a carbon dioxide reforming reaction in which the reducing agent is reformed with carbon dioxide, and a thermal decomposition reaction in which the reducing agent is thermally decomposed. The method for recovering sensible heat from the exhaust gas generated in the metallurgical furnace according to claim 1, wherein: 上記水蒸気改質反応に、排ガスダクトの蒸気管から発生した水蒸気を用いることを特徴とする請求項２に記載の冶金炉発生排ガスからの顕熱回収方法。 The method for recovering sensible heat from a metallurgical furnace-generated exhaust gas according to claim 2, wherein steam generated from a steam pipe of an exhaust gas duct is used for the steam reforming reaction. 上記炭酸ガス改質反応に、冶金炉から発生する排ガス中の炭酸ガスを用いることを特徴とする請求項２に記載の冶金炉発生排ガスからの顕熱回収方法。 The method for recovering sensible heat from the exhaust gas generated from the metallurgical furnace according to claim 2, wherein carbon dioxide gas in the exhaust gas generated from the metallurgical furnace is used for the carbon dioxide reforming reaction. 上記熱交換チューブとして、転炉排ガス処理設備に設けられた接触ボイラーを用いることを特徴とする請求項１〜４のいずれか１項に記載の冶金炉発生排ガスからの顕熱回収方法。 The method for recovering sensible heat from a metallurgical furnace-generated exhaust gas according to any one of claims 1 to 4, wherein a contact boiler provided in a converter exhaust gas treatment facility is used as the heat exchange tube. 上記吸熱化学反応を、固定床触媒の存在下で行うことを特徴とする請求項１〜５のいずれか１項に記載の冶金炉発生排ガスからの顕熱回収方法。 The method for recovering sensible heat from a metallurgical furnace-generated exhaust gas according to any one of claims 1 to 5, wherein the endothermic chemical reaction is performed in the presence of a fixed bed catalyst. 上記固定床触媒が、転炉ダストを含む成型物であることを特徴とする請求項６に記載の冶金炉発生排ガスからの顕熱回収方法。 The method for recovering sensible heat from a metallurgical furnace-generated exhaust gas according to claim 6, wherein the fixed bed catalyst is a molded article containing converter dust. 冶金炉から排出される高温の排ガスを熱源として、冶金炉の排ガスダクト内に設置された熱交換チューブ内で還元剤を吸熱化学反応させることにより、上記高温の排ガスを冷却することを特徴とする冶金炉発生排ガスの冷却方法。 Using the high-temperature exhaust gas discharged from the metallurgical furnace as a heat source, the above-described high-temperature exhaust gas is cooled by causing an endothermic chemical reaction of the reducing agent in a heat exchange tube installed in the exhaust gas duct of the metallurgical furnace. Cooling method for exhaust gas generated from metallurgical furnace. 上記吸熱化学反応は、還元剤を水蒸気で改質する水蒸気改質反応であり、上記水蒸気として排ガスダクトの蒸気管から発生した水蒸気を用いることを特徴とする請求項８に記載の冶金炉発生排ガスの冷却方法。 9. The metallurgical furnace-generated exhaust gas according to claim 8, wherein the endothermic chemical reaction is a steam reforming reaction in which a reducing agent is reformed with steam, and steam generated from a steam pipe of an exhaust gas duct is used as the steam. Cooling method. 上記吸熱化学反応は、還元剤を炭酸ガスで改質する炭酸ガス改質反応であり、上記炭酸ガスとして冶金炉から発生する排ガス中の炭酸ガスを用いることを特徴とする請求項８に記載の冶金炉発生排ガスの冷却方法。 9. The endothermic chemical reaction is a carbon dioxide reforming reaction in which a reducing agent is reformed with carbon dioxide, and carbon dioxide in exhaust gas generated from a metallurgical furnace is used as the carbon dioxide. Cooling method for exhaust gas generated from metallurgical furnace. 上記熱交換チューブとして、転炉排ガス処理設備に設けられた接触ボイラーを用いることを特徴とする請求項８〜１０のいずれか１項に記載の冶金炉発生排ガスの冷却方法。 The method for cooling a metallurgical furnace-generated exhaust gas according to any one of claims 8 to 10, wherein a contact boiler provided in a converter exhaust gas treatment facility is used as the heat exchange tube.
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