JP3813835B2

JP3813835B2 - Water recovery system from combustion exhaust gas

Info

Publication number: JP3813835B2
Application number: JP2001149659A
Authority: JP
Inventors: 宏和高橋; 知彦宮本; 信幸穂刈; 森原　　淳; 真一稲毛
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2001-05-18
Filing date: 2001-05-18
Publication date: 2006-08-23
Anticipated expiration: 2021-05-18
Also published as: JP2002338973A

Description

【０００１】
【発明の属する技術分野】
本発明は、重質油を超臨界水中に溶解して軽質化し、軽質化燃料と超臨界水の混合燃料を燃焼するシステムの、燃焼排ガス中に含まれる水分の回収システムに関するものである。
【０００２】
【従来の技術】
超臨界水に重質油を溶解し、重質油を軽質化して燃料ガス、軽質油に転換する技術は周知である。特開２０００−１０９８５０号公報には、重質油を超臨界水で軽質化して高効率発電をする技術が提案されている。この方式では、水の臨界点（２２．１ＭＰａ、３７４℃）以上の温度、圧力で水に重質油を溶解して軽質化する。軽質油および超臨界水は減圧、冷却され、油水分離工程で燃料ガス、軽質油および水に分離される。これにより、重質油は燃料ガス、軽質油は高効率発電燃料として使うことができる。この方式では、油水分離工程で分離した水にはアルカリ等の添加物や還元性のアンモニア、シアン化物、硫化水素が含まれており、これらの化合物を処理するために水を系外へ抜き出すようにしている。
【０００３】
一方、重質油を超臨界水で軽質化し、燃料と水を分離せずに燃焼器へ導くシステムがある。この方式においては燃料と水の減圧、冷却、分離工程を必要としないため、燃料の減圧、冷却にともなうエネルギー損失がない。また、重質油と水の混合燃料は燃焼するため、燃料中の硫黄や微量金属分は酸化し、環境装置で処理しやすくなる。
【０００４】
【発明が解決しようとする課題】
燃料とともに水分も燃焼器へ導く方式では、水を多量に使用する。水の使用量を減らすためには、燃焼排ガスから温水を回収するのが有効である。
【０００５】
本発明の課題は、重質油を超臨界水で軽質化し、混合したまま燃焼するシステムにおいて、燃焼排ガスから回収した温水中に吸収されている硫黄酸化物や金属酸化物等の不純物を分離、除去し、再度超臨界水反応器に戻して重質油の軽質化に利用することのできるシステムを提供することにある。
【０００６】
【課題を解決するための手段】
すなわち、本発明は、重質油を超臨界水で軽質燃料化し、得られた改質燃料で発電するシステムにおいて、不純物除去後の超臨界水を、前記軽質燃料化の工程で使用される超臨界水の一部として回収・再利用することを特徴とするものである。
【０００７】
その具体的一例は、燃焼排ガスを冷却し凝縮水を回収する冷却工程、回収した凝縮水を貯留しアルカリまたは酸化剤を添加する調整工程、調整された凝縮水を加圧、加熱し超臨界水反応させる反応工程、反応工程からの超臨界水中の不純物を分離除去する捕捉工程から構成される。
【０００８】
一般に重質油を超臨界処理し、得られた改質燃料で高効率発電を達成するシステムは、超臨界水と重質油を反応させる改質反応部、重質油中の不純物を分離する分離部、改質燃料を燃焼し、発電する燃焼器一体型のガスタービン、ガスタービンから排出される燃焼排ガスの熱回収部、燃焼排ガス中のＮＯ_X、ＳＯ_X、塵を除去する環境対策部から構成される。
【０００９】
冷却工程では間接冷却法により、燃焼排ガスを冷媒で冷却し、凝縮水を得る。冷媒には海水、工業用水、クーリングタワー水等が利用できるが、好ましくはシステム内にある低温流体、例えば重質油、超臨界水用の給水、熱回収部に供給する給水等を用いるとよい。冷却工程での温度は９０〜５０℃、好ましくは５０〜６０℃程度とする。
【００１０】
冷却工程はＮＯ_X、ＳＯ_X、塵を除去する環境対策部の後流、すなわち燃焼排ガス温度の最も低い部分に設置し、燃焼排ガスと冷媒を間接接触させて、燃焼排ガス中の水分を凝縮させる。環境対策部の後流に該冷却工程を設置することは、燃焼排ガス中のＮＯ_X、ＳＯ_X、塵が極めて低いレベルにまで除去されており、冷却工程での凝縮水中にＮＯ_X、ＳＯ_Xの溶け込みが少ない、すなわち装置の腐食が軽減できること、塵の混入によるポンプ類の磨耗軽減を図ることにある。
【００１１】
冷却工程で回収された凝縮水は調整工程に送る。調整工程は凝縮水を貯留するタンク、凝縮水中の硫黄分（Ｓ分）、炭素分（Ｃ）を測定する測定器、アルカリ（ＮａＯＨ、ＫＯＨ）および酸化剤（Ｈ₂Ｏ₂）を供給する添加装置から構成される。凝縮水中には微量のＳ化合物（硫酸塩、ジチオン酸）が存在し、凝縮水をそのまま加熱し高温・高圧水にすると材料の腐食が早まる。そこで、凝縮水中のＳ分を測定し、その量に見合ったアルカリ（ＮａＯＨ、ＫＯＨ）を等モル以上好ましくは1〜2倍モル添加し、腐食性の少ないＮａ₂ＳＯ₄、Ｋ₂ＳＯ₄等にする。アルカリは理論上前記反応式に示される理論量を添加すればよいが、反応効率を考慮して、最大２倍モルの供給とする。また、Ｃ分を測定し、ＣとＳのモル量に対しＨ₂Ｏ₂を（２Ｈ₂Ｏ₂＝２Ｈ₂Ｏ+Ｏ₂、すなわちＯ₂が１モルとは２モルのＨ₂Ｏ₂）２倍モル以上、好ましくは２〜４倍モル添加しＣ分をＣＯ₂ガスに転換して、加熱、高温化時に反応管内で起こるＣの析出を防止する。またＳ化合物はＳＯ₂或いはＳＯ₄に転換して、アルカリ金属と反応させる。
【００１２】
調整工程からの凝縮水はポンプで水の臨界圧以上に加圧、好ましくは２２〜２５ＭＰａに加圧し、反応工程に送る。反応工程は熱回収器内に設置された伝熱管で構成され、伝熱管内に送られた添加剤含有凝縮水は該伝熱管内で３７４℃以上、好ましくは３８０〜４１０℃に加熱され、超臨界水となる。また、アルカリ添加物はＳ分と反応し、反応でＮａ₂ＳＯ₄になり、Ｃ分はＣＯ₂となる。これらの化合物は超臨界水に溶解された状態で存在させるため、伝熱管内温度は３７４〜４１０℃に保つ。反応工程で反応させた超臨界水は次の捕捉工程に送る。
【００１３】
捕捉工程は伝熱管と開口接続した捕捉管で構成される。捕捉管内には石灰石（ＣａＣＯ₃）、ドロマイト（ＭｇＯ、ＣａＣＯ₃からなる物質）等を充填し、少なくとも反応工程の温度よりも捕捉管温度を高くする、好ましくは４１０℃〜５００℃とする。捕捉管内では充填された石灰石と不純物を溶解した超臨界水が接触することで、不純物は石灰石表面上に析出、あるいは反応して石灰石に捕捉される。これにより不純物を殆ど含まない超臨界水が得られ、該超臨界水は重質油の改質化反応に再度利用できるので、廃水として系外に放出する必要がなくなる。
【００１４】
なお、凝縮水中に極微量の重金属分が存在する場合にも、本方式は適用可能である。
【００１５】
凝縮水中の微量金属分は殆どが酸化金属の形態で存在しており、凝縮水と共にポンプで送られた酸化金属分は捕捉工程で、充填剤である石灰石と反応しＣａＯ・Ｖ₂Ｏ₅、ＣａＯ・Ｎａ₂Ｏ・Ｖ₂Ｏ₅として石灰石上に固着するので、超臨界水とは分離される。
【００１６】
このように、重質油を超臨界水で軽質化し、混合したまま燃焼するシステムにおいて、燃焼排ガスから回収した温水中に吸収されている硫黄酸化物や金属酸化物等の不純物を分離、除去し、再度超臨界水反応器に戻して重質油の軽質化に利用することができ、水の使用量を減らすことができる。また、廃水を系外に放出する必要がなく、廃水処理も不要となる。
【００１７】
【発明の実施の形態】
（実施例１）
以下、図面1を用いて本発明の実施形態を説明する。
【００１８】
図1は重質油を超臨界処理して改質燃料を製造し、得られた改質燃料をガスタービン用燃焼器で燃焼、燃焼ガスでガスタービンを駆動する発電システムである。ガスタービンからの燃焼排ガスは熱回収器で熱エネルギを回収され、脱硝、脱硫、脱塵等の環境装置で浄化される。その後、冷却工程で冷却され、燃焼排ガス中の水分は凝縮、分離回収される。分離回収された凝縮水にはアルカリとＨ₂Ｏ₂を添加後、ポンプで加圧し反応器、捕捉器で加熱、水の臨界点以上の温度、圧力で反応させ、凝縮水中の不純物を捕捉、得られた超臨界水で重質油を改質するシステムである。
【００１９】
重質油改質工程1には超臨界水と重質油を供給し、超臨界水による加水分解作用により重質油を軽質化する。超臨界水はバルブ２４を介して２５ＭＰａ、４５０℃で重質油改質工程に供給する。一方、重質油は配管２０を介して冷却工程１４内の熱交換器２９に供給し、燃焼排ガスと間接熱交換させ、重質油を加熱すると共に燃焼排ガスを冷却し燃焼排ガス中の水分を凝縮させ凝縮水にする。熱交換器２９で加熱された重質油は供給管２１を介して重質油改質工程に供給され、該重質油改質工程で３８０℃、２５ＭＰａで改質される。改質ガスおよび超臨界水は金属分分離工程２で加熱され４２０℃、２５ＭＰａで金属分を分離され、燃焼器３で燃焼される。燃焼ガスはガスタービン４を駆動した後、５４０℃、１気圧程度で熱回収器５に入る。熱回収器５には通常の蒸気発生器と本発明になる反応工程１２、捕捉工程１３が挿入されており、燃焼ガスとの間接熱交換により熱を回収する。熱回収器５を出た燃焼排ガスは環境装置６でＳＯｘ、ＮＯｘ、塵を除去され、冷却工程１４に至る。冷却工程１４で得られた凝縮水は排水管２８により、凝縮水タンク３０に貯留する。貯留された凝縮水は測定器８によりＳ分、Ｎ分、Ｃ分を測定され、その量を求められる。計測したＳ分のモル数に対し１．５倍モルのＮａＯＨをアルカリ添加装置９により凝縮水タンク３０に供給する。また、Ｓ分のモル数とＣ分のモル数を加算したモル数の３倍モルのＨ₂Ｏ₂を酸化剤添加装置１０により凝縮水タンク３０に供給する。なお、添加するアルカリは、ＮａＯＨ以外に凝縮水中の不純物処理に対して同様の働きをするＫＯＨでもよい。
【００２０】
これら測定器８、アルカリ添加装置９、酸化剤添加装置１０および凝縮水タンク３０から構成される調整工程７からの凝縮水は加圧ポンプ１１で２５ＭＰaに加圧され、熱回収器５内に設置した反応工程１２に送られる。反応工程１２では凝縮水が３８０℃にまで加熱され、水が超臨界水となる。また、添加物であるＨ₂Ｏ₂はＨ₂Ｏと１／２Ｏ₂となり、Ｏ₂は超臨界水に溶解したＣ分と反応しＣＯ₂に、Ｓ分はＳＯ₂になる。さらにＳＯ₂は添加物のＮａＯＨと反応してＮａ₂ＳＯ₄となる。これらの物質はいずれも３７４℃〜４１０℃の範囲では超臨界水に完全溶解している。反応工程を出た物質は捕捉工程１３に導入する。捕捉工程１３には充填剤供給管２７から石灰石等の充填剤を充填しておく。また、反応工程から流入する流体の温度を４３０℃程度まで高める。これにより超臨界水に溶解していたＮａ₂ＳＯ₄、ＳＯ₄等のＳ化合物は石灰石表面に析出、さらには石灰石と反応してＣａＳＯ₄となり石灰石に固定される。該工程で不純物を除去された超臨界水は排出管２２、圧力調節弁２５、戻し管２３を経て重質油改質工程１に戻し、再利用する。
【００２１】
本実施例では重質油を超臨界水処理した改質燃料を燃焼した際に回収した凝縮水を調整工程７、加圧ポンプ１１、反応工程１２、捕捉工程１３および圧力調節弁２５からなる構成で凝縮水中の不純物除去を実施した。その結果は下記である。
ケース１
凝縮水：Ｓ分３モル、Ｃ分４．２モル
ＮａＯＨ添加量：４．５モル
Ｈ₂Ｏ₂添加量：１０．８モル
反応工程：温度３８０℃、圧力２５ＭＰａ
捕捉工程：温度４３０℃、圧力２５ＭＰａ、石灰石を充填
圧力調節弁２５から排出した超臨界水のＳ分０．０３モル、Ｃ分０．００２モル
ケース２
凝縮水：Ｓ分３モル、Ｃ分４．２モル
ＫＯＨ添加量：４．５モル
Ｈ₂Ｏ₂添加量：１０．８モル
反応工程：温度３８０℃、圧力２５ＭＰａ
捕捉工程：温度４３０℃、圧力２５ＭＰａ、石灰石を充填
圧力調節弁２５から排出した超臨界水のＳ分０．０３モル、Ｃ分０．００２モル
ケース３
凝縮水：Ｓ分３モル、Ｃ分４．２モル
ＮａＯＨ添加量：３モル
Ｈ₂Ｏ₂添加量：１０．８モル
反応工程：温度３８０℃、圧力２５ＭＰａ
捕捉工程：温度４３０℃、圧力２５ＭＰａ、石灰石を充填
圧力調節弁２５から排出した超臨界水のＳ分０．０５モル、Ｃ分０．００２モル
（実施例２）
本実施例では最終的に大気放出する排ガス中の白煙防止と熱交換器５からの燃焼排ガスの冷却効果を高めるために構成されたもので、図２を用いて説明する。
【００２２】
燃焼排ガスは熱回収器５、排ガス加熱器１０８により温度を下げた後、冷却工程１４に供給される。冷却工程１４ではスプレー装置１０４から後述する吸収液１１３が噴射され、燃焼排ガス中に含まれた水分が冷却され、硫黄酸化物および窒素酸化物を含んだ凝縮水１０６になる。さらに燃焼排ガスはミスト捕集機１０７によりミストを除去した後、排ガス加熱器１０８で加熱して白煙を生じないようにする。凝縮水１０６の一部はポンプ１０５で加圧され、ｐＨ調整機１０３でｐＨを調整された後、吸収液１１３としてスプレー装置１０４に供給される。凝縮水の他方は調整工程７に送られる。
【００２３】
スプレー装置１０４は水を微細な液滴として噴霧する装置であり、例えばスプレーノズルを燃焼排ガスの流れ方向に対して垂直な面に複数個設置する構成とする。スプレー塔での気液接触により、燃焼排ガスの温度が低下し、気体として存在する燃焼排ガス中の水分は凝縮して液体となる。また、燃焼排ガス中のＳＯ₂はｐＨ調整された吸収液に吸収される。吸収を促進し、燃焼排ガスからの脱硫効率を向上させるために、燃焼排ガス中のＳＯ₂を液中に吸収させる反応を促進する。気相中のＳＯ₂を液中に吸収する反応を促進するために、吸収液のｐＨは３.８以上とする。
【００２４】
一方、調整工程７、反応工程１２で硫黄酸化物を完全酸化するためにＨ₂Ｏ₂を添加するが、その添加量を下げるために冷却工程１４で硫黄酸化物を空気中の酸素と反応させて硫酸にする。吸収液のｐＨが２〜４においては完全に酸化されていない硫黄酸化物であるジチオン酸の生成が最大になり、ｐＨが６．０以上ではジチオン酸は生成しなかった。これらのことから吸収液のｐＨは６．０以上に調整した。吸収液に用いるｐＨ調整剤は、消灰石や生石灰、苛性ソーダを使用する。
【００２５】
吸収液のｐＨの調節は、凝縮水１０６のｐＨをｐＨ計測器１０１で調べ、ｐＨが６．０以上になるように、ｐＨ調整剤供給コントローラ１０２からｐＨ供給機１０３へｐＨ調整剤を供給するように制御する。吸収液の硫黄および窒素化合物濃度の調節システムは、ｐＨ調整と同様に、硫黄、窒素化合物計測器１１４で調べ、一定濃度以上になった場合、補給水コントローラ１１５からｐＨ調整機１０３へ補給水を供給し、ｐＨを６．０以上にするように制御する。凝縮水１０６の量の調節は、液面計１１９で液面を検知し、液面コントローラ１１８でバルブ１１７を開閉し、凝縮水量を一定に保つよう制御する。
【００２６】
本実施例では燃焼排ガスから凝縮水を回収する熱交換器５、排ガス加熱器１０８、冷却工程７、スプレー装置１０４、ミスト捕集機１０７、ｐＨ調整機１０３およびポンプ１０５からなる構成で凝縮水中の不純物除去を実施した。その結果は下記である。
ケース１
燃焼排ガス１０９中Ｓ分：７０ｐｐｍ
燃焼排ガス１０９温度：１６０℃
スプレー装置１０４中の水のｐＨ：１１．４
吸収液１１３温度：４０℃
吸収液１１３ｐＨ：１１．３
ｐＨ調整剤：ＮａＯＨ
凝縮水１０６中ジチオン酸濃度：０．５ｐｐｍ
排ガス加熱器１０８中のＳ分：３０ｐｐｍ
排ガス加熱器１０８中の排ガス温度：９０℃
ケース２
燃焼排ガス１０９中Ｓ分：７０ｐｐｍ
燃焼排ガス１０９温度：１３０℃
スプレー装置１０４中の水のｐＨ：１１．４
吸収液１１３温度：４０℃
吸収液１１３ｐＨ：１１．３
ｐＨ調整剤：ＮａＯＨ
凝縮水中１０６ジチオン酸濃度：０．７ｐｐｍ
排ガス加熱器１０８中のＳ分：２０ｐｐｍ
排ガス加熱器１０８中の排ガス温度：９０℃
この実施例２によれば、ガスタービンの燃焼排ガスから水を効率よく回収し、しかもガスタービンから排気された燃焼排ガスが白煙を生じないという効果がある。
（実施例３）
本実施例では調整工程７の調整剤を適量供給し、反応工程１２の配管の腐食速度を低下するために構成されるもので、図３を用いて説明する。硫黄酸化物（Ｓ₂Ｏ₃ ^2-、ＳＯ₃ ^2-、Ｓ₂Ｏ₆ ^2-）、ＴＯＣ、ＣＯＤを測定する測定器８、ｐＨ調整剤供給機９、酸化剤供給機１０および凝縮水タンク３２からなる構成で凝縮水Ｈ₂Ｏ₂供給量を適正にすることにより、反応器の腐食を押さえることができる。
【００２７】
調整工程７では、ｐＨ調整と酸化されうる物質を分析し、凝縮水３０に添加剤と酸化剤を添加する。硫黄濃度と炭素濃度の計測のため、凝縮水３０は撹拌機３１で撹拌して凝縮水タンク３２から採取する。凝縮水タンク３２では撹拌機３１で凝縮水を撹拌して水溶液濃度を均一にする。凝縮水タンク３０に貯留された凝縮水中の硫黄分を測定する硫黄酸化物測定器１３２ではチオ硫酸、亜硫酸、ジチオン酸等酸化され得る硫黄酸化物濃度をイオンクロマトグラフ法で測定する。各イオン種が酸化して硫酸になった場合のｐＨの変化を計算し、反応終了後にｐＨが７から１２になるようｐＨ調整剤の供給量を濃度調整コントローラ１３１で調節し、凝縮水タンク３２に供給する。また、各イオン種に対する酸化に必要なＨ₂Ｏ₂の量を計算する。
【００２８】
炭素分を測定する測定器８では、全有機炭素（ＴＯＣ）を測定する。ＴＯＣ測定器１３３でＴＯＣを測定する場合には過酸化水素供給量を、ＴＯＣを酸化するための酸素量に対して２倍から３倍当量のＨ₂Ｏ₂量を計算する。
【００２９】
炭素以外の元素を酸化するための酸素供給量を決めるには化学的酸素要求量（ＣＯＤ）を用いる。ただし、ＣＯＤの測定では理論的に必要な酸素量より小さい値になる。ＣＯＤの測定にはＣＯＤ測定器１３４を用いる。亜硫酸やジチオン酸のＣＯＤを測定すると、実際に酸化するために必要な酸素量の１／８および１／４の値になる。そこで、ＣＯＤ値から硫黄酸化物を完全に酸化するために必要な量の酸素量を減じた分のＨ₂Ｏ₂量の２から３倍当量を計算する。
【００３０】
硫黄酸化物、ＴＯＣ、ＣＯＤから計算したＨ₂Ｏ₂量を濃度調整コントローラ１３１で調整し、酸化剤添加装置１０で凝縮水供給管１３５に供給する。
【００３１】
本実施例では凝縮水中の不純物をジチオン酸、有機物、金属イオンとし、ＳＵＳ３１６の配管を用い、４５０℃、２５ＭＰａで酸化剤にＨ₂Ｏ₂、ｐＨ調整剤にＮａＯＨを用いて酸化した。原液中の各成分の濃度と処理後の液中の各成分濃度、腐食速度および孔食の有無を表１に示す。
【００３２】
【表１】

【００３３】
この実施例３によれば、硫酸を含む凝縮水を超臨界水酸化した場合にも孔食を生じさせることなく、凝縮水中の不純物を完全に酸化することができる。
（実施例４）
本実施例では重質油と超臨界水の混合燃料を燃焼した後の水を回収、再利用するために添加するＨ₂Ｏ₂量を低減するために構成されるもので、図１を用いて説明する。
【００３４】
重質油を燃焼して、燃焼排ガスから不純物を採取した場合には、燃焼排ガスから回収した凝縮水１０６中に硫酸、亜硫酸、硝酸、亜硝酸、Ｖ₂Ｏ₅、金属酸化物等が存在する。これらは、超臨界水中で塩を生成しやすく、捕捉工程１３で分離除去が容易である。
【００３５】
従来の構成を示す概略図を図４に示す。この方式は、タンク３２１からポンプ３２２を用いて加圧し、熱交換器３２３で加熱して超臨界状態にする。超臨界反応器３２４で酸素源と反応して抽出器３２５で冷却、減圧して気液分離器３２７でガス成分を取り出し、さらに排水分離器３２８で軽質油と水に分離する。分離した水中にはＮＨ₃、Ｈ₂Ｓ、シアン化物およびナトリウム、カリウム、バナジウムイオン等の金属が水中に溶け込む。また、油分が水中に残るためＣＯＤ、ＴＯＣが高くなる。
【００３６】
表２に従来工程排水と本実施例の凝縮水性状を示す。
【００３７】
【表２】

【００３８】
この実施例４によれば、凝縮水から処理しやすい含有成分を処理して、凝縮水中の不純物を完全に酸化する事ができる。
（実施例５）
本実施例では最終的に大気放出する燃焼排ガス中の水分を回収し白煙発生を防止するために構成するものである。さらには、水回収率を上げることにより、発電効率を上げるために構成するもので、図２を用いて説明する。
【００３９】
燃焼排ガスは熱回収器５、排ガス加熱器１０８により温度を下げた後、冷却工程１４に供給される。冷却工程１４ではスプレー装置１０４から吸収液１１３が噴射され、排ガス中に含まれた水分が冷却され、硫黄酸化物および窒素酸化物を含んだ凝縮水１０６になる。さらに燃焼排ガスはミスト捕集機１０７によりミストを除去した後、排ガス加熱器１０８で加熱して白煙を生じないようにする。
【００４０】
冷却工程１４において燃焼排ガス１０９から回収した凝縮水の水回収条件が与える影響について述べる。水回収条件の変化により、発電効率に与える影響因子としては、ａ）圧損の変化（冷却工程１４の有無による圧力比の変化）、ｂ）熱回収下限温度（燃焼排ガス管１１０中のガス温度）、ｃ）補給水温度および量（水回収時の潜熱回収による予熱効果）がある。表３に水回収条件とその影響についてまとめる。
【００４１】
【表３】

【００４２】
本実施例により水回収率を１００％にすることで、発電効率を０．２％高くできる。さらに、補給水量も低減できる。また、従来は白煙発生防止のために燃焼排ガス温度を高くしていたが、水を回収して露点が下がるので、系外へ排出する燃焼排ガス温度を下げることができる。
【００４３】
【発明の効果】
本発明によれば、重質油を超臨界水で軽質化し、混合したまま燃焼するシステムにおいて、燃焼排ガスから回収した温水中に吸収されている硫黄酸化物や金属酸化物等の不純物を分離、除去し、再度超臨界水反応器に戻して重質油の軽質化に利用することができ、水の使用量を減らすことができる。
【図面の簡単な説明】
【図１】本発明の一実施形態の構成を示す概略図である。
【図２】本発明の冷却工程の実施形態例を示す図である。
【図３】本発明の調整工程の実施形態例を示す図である。
【図４】従来の構成を示す概略図である。
【符号の説明】
1…重質油改質工程、2…金属分分離工程、3…燃焼器、4…ガスタービン、5…熱回収器、6…環境装置、7…調整工程、8…測定器、9…アルカリ添加装置、10…酸化剤添加装置、11…加圧ポンプ、12…反応工程、13…捕捉工程、14…冷却工程、15…重質油供給ポンプ、20…配管、21…供給管、22…排出管、23…戻し管、24…バルブ、25…圧力調節弁、26…充填剤排出管、27…充填剤供給管、28…排出配管、29…熱交換器、30…凝縮水タンク、31…撹拌機、32…凝縮水タンク、101…pH計測器、102…ｐＨ調整剤供給コントローラ、103…ｐH調整機、104…スプレー装置、105…凝縮水戻しポンプ、106…凝縮水、107…ミスト捕集機、108…排ガス加熱器、109…燃焼排ガス、110…燃焼排ガス管、111…燃焼排ガス、112…重質油熱交換配管、113…吸収液、114…硫黄分、窒素分計測機、115…補給水供給コントローラ、116…凝縮水の一部、117…バルブ、118…液面コントローラ、119…液面計、131…濃度調整コントローラ、132…硫黄酸化物測定器、133…ＴＯＣ測定器、134…ＣＯＤ測定器、135…凝縮水供給管、321…タンク、322…ポンプ、323…熱交換器、324…超臨界反応器、325…抽出器、326…減圧弁、327…気液分離器、328…排水分離器、329…塩分離器、331…ポンプ（水の供給手段）、332…コンプレッサ（酸素源の供給手段）、333…スクリーン工程、334…加圧浮上工程、335…生物処理工程、336…凝集沈殿処理工程、337…砂ろ過工程。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a system for recovering moisture contained in combustion exhaust gas in a system in which heavy oil is dissolved and lightened in supercritical water to burn a mixed fuel of lightened fuel and supercritical water.
[0002]
[Prior art]
The technology of dissolving heavy oil in supercritical water, lightening the heavy oil and converting it to fuel gas and light oil is well known. Japanese Patent Application Laid-Open No. 2000-109850 proposes a technique for lightening heavy oil with supercritical water for high-efficiency power generation. In this system, heavy oil is dissolved in water at a temperature and pressure higher than the critical point of water (22.1 MPa, 374 ° C.) and lightened. Light oil and supercritical water are decompressed and cooled, and separated into fuel gas, light oil and water in an oil-water separation process. As a result, heavy oil can be used as fuel gas, and light oil can be used as highly efficient power generation fuel. In this method, the water separated in the oil / water separation step contains additives such as alkali, reducing ammonia, cyanide, and hydrogen sulfide, and water is taken out of the system to treat these compounds. I have to.
[0003]
On the other hand, there is a system that lightens heavy oil with supercritical water and guides it to the combustor without separating fuel and water. Since this method does not require depressurization, cooling and separation steps of fuel and water, there is no energy loss associated with depressurization and cooling of the fuel. In addition, since the fuel mixture of heavy oil and water burns, sulfur and trace metal components in the fuel are oxidized and are easily treated by an environmental device.
[0004]
[Problems to be solved by the invention]
In a system that introduces moisture together with fuel to the combustor, a large amount of water is used. In order to reduce the amount of water used, it is effective to recover hot water from the combustion exhaust gas.
[0005]
The problem of the present invention is to separate impurities such as sulfur oxides and metal oxides absorbed in warm water recovered from combustion exhaust gas in a system in which heavy oil is lightened with supercritical water and burned while mixed. It is to provide a system that can be removed and returned to the supercritical water reactor and used for lightening heavy oil.
[0006]
[Means for Solving the Problems]
That is, the present invention provides a system for converting heavy oil into light fuel with supercritical water and generating power with the resulting reformed fuel, and supercritical water after impurities removal is used in the light fuel process. It is characterized by being recovered and reused as part of critical water.
[0007]
Specific examples are a cooling process for cooling combustion exhaust gas and collecting condensed water, an adjustment process for storing the collected condensed water and adding an alkali or an oxidizing agent, and pressurizing and heating the adjusted condensed water to supercritical water. The reaction step comprises a reaction step, and a capture step for separating and removing impurities in supercritical water from the reaction step.
[0008]
In general, the system that achieves high-efficiency power generation with supercritical processing of heavy oil and the resulting reformed fuel separates the impurities in the heavy oil and the reforming reaction section that reacts the supercritical water and heavy oil. Separation unit, combustor-integrated gas turbine that burns reformed fuel to generate electricity, heat recovery unit of combustion exhaust gas discharged from the gas turbine, environmental countermeasure unit that removes NO _x , SO _x , and dust in the combustion exhaust gas Consists of
[0009]
In the cooling step, the flue gas is cooled with a refrigerant by an indirect cooling method to obtain condensed water. Seawater, industrial water, cooling tower water, and the like can be used as the refrigerant. Preferably, low-temperature fluid in the system, for example, heavy oil, supercritical water feed water, feed water supplied to the heat recovery unit, or the like may be used. The temperature in the cooling step is 90 to 50 ° C, preferably about 50 to 60 ° C.
[0010]
The cooling process is installed in the downstream of the environmental measures section that removes NO _x , SO _x , and dust, that is, at the lowest part of the combustion exhaust gas temperature, and the combustion exhaust gas and the refrigerant are brought into indirect contact to condense the moisture in the combustion exhaust gas. . The installation of the cooling process in the downstream of the environmental measures section removes NO _x , SO _x , and dust in the combustion exhaust gas to an extremely low level, and NO _x , SO _x in the condensed water in the cooling process. The purpose of this is to reduce the wear of pumps due to dust contamination.
[0011]
The condensed water collected in the cooling process is sent to the adjustment process. The adjustment process is a tank for storing condensed water, a measuring device for measuring sulfur content (S content) and carbon content (C) in the condensed water, addition of supplying alkali (NaOH, KOH) and oxidizing agent (H ₂ O ₂ ). Consists of devices. Trace amounts of S compounds (sulfate, dithionic acid) are present in the condensed water, and if the condensed water is heated as it is to produce high temperature / high pressure water, the corrosion of the material is accelerated. Accordingly, the S content in the condensed water is measured, and an alkali (NaOH, KOH) corresponding to the amount is added in an equimolar amount or more, preferably 1 to 2 moles, so that Na ₂ SO ₄ , K ₂ SO _4, etc. with less corrosivity To. The alkali may be theoretically added in the theoretical amount shown in the above reaction formula, but in consideration of the reaction efficiency, it is supplied at a maximum of 2 times mole. Further, C content is measured, and H ₂ O ₂ is added to the molar amount of C and S (2H ₂ O ₂ = 2H ₂ O + O ₂ , that is, 1 mol of O ₂ is 2 mol of H ₂ O ₂ ). Addition of 2 moles or more, preferably 2 to 4 moles, converts C to CO ₂ gas to prevent precipitation of C that occurs in the reaction tube when heated and heated. The S compound is converted to SO ₂ or SO ₄ and reacted with an alkali metal.
[0012]
The condensed water from the adjustment step is pressurized to a pressure higher than the critical pressure of water by a pump, preferably 22 to 25 MPa, and sent to the reaction step. The reaction step is composed of a heat transfer tube installed in the heat recovery unit, and the additive-containing condensed water sent into the heat transfer tube is heated to 374 ° C. or higher, preferably 380 to 410 ° C. in the heat transfer tube. It becomes critical water. Further, the alkali additive reacts with the S component, and the reaction becomes Na ₂ SO ₄ , and the C component becomes CO ₂ . Since these compounds are present in a state dissolved in supercritical water, the temperature in the heat transfer tube is maintained at 374 to 410 ° C. The supercritical water reacted in the reaction step is sent to the next capture step.
[0013]
The trapping process is composed of a trap tube that is open-connected to the heat transfer tube. The trap tube is filled with limestone (CaCO ₃ ), dolomite (substance made of MgO, CaCO ₃ ), etc., and at least the trap tube temperature is set higher than the temperature of the reaction step, preferably 410 ° C. to 500 ° C. In the trapping tube, the filled limestone and the supercritical water in which the impurities are dissolved come into contact with each other, so that the impurities are deposited on the surface of the limestone or are reacted and trapped in the limestone. As a result, supercritical water containing almost no impurities can be obtained, and the supercritical water can be reused for the reforming reaction of heavy oil, so that it is not necessary to discharge it as waste water out of the system.
[0014]
Note that this method can also be applied when a very small amount of heavy metal is present in the condensed water.
[0015]
Most of the trace metal content in the condensed water exists in the form of metal oxide, and the metal oxide content pumped with the condensed water reacts with the limestone which is the filler in the trapping process, and CaO · V ₂ O ₅ , since fixed on limestone as _{_{CaO · Na 2 O · V 2}} O 5, and supercritical water are separated.
[0016]
In this way, in a system where heavy oil is lightened with supercritical water and burned while mixed, impurities such as sulfur oxides and metal oxides absorbed in warm water recovered from combustion exhaust gas are separated and removed. It can be returned to the supercritical water reactor again and used for lightening heavy oil, and the amount of water used can be reduced. Further, it is not necessary to discharge waste water out of the system, and waste water treatment is not necessary.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
[0018]
Fig. 1 shows a power generation system in which heavy oil is supercritically processed to produce reformed fuel, the resulting reformed fuel is burned in a gas turbine combustor, and the gas turbine is driven with combustion gas. The combustion exhaust gas from the gas turbine recovers thermal energy by a heat recovery device and is purified by an environmental device such as denitration, desulfurization, and dust removal. Then, it cools by a cooling process and the water | moisture content in combustion exhaust gas is condensed and isolate | separated and collected. After adding alkali and H ₂ O ₂ to the separated and recovered condensed water, pressurize it with a pump, heat it with a reactor and a trap, react it at a temperature and pressure above the critical point of water, and trap impurities in the condensed water. It is a system for reforming heavy oil with the obtained supercritical water.
[0019]
In the heavy oil reforming step 1, supercritical water and heavy oil are supplied, and the heavy oil is lightened by hydrolysis with supercritical water. Supercritical water is supplied to the heavy oil reforming process at 25 MPa and 450 ° C. through the valve 24. On the other hand, the heavy oil is supplied to the heat exchanger 29 in the cooling process 14 through the pipe 20 and indirectly heat-exchanged with the combustion exhaust gas, thereby heating the heavy oil and cooling the combustion exhaust gas to remove moisture in the combustion exhaust gas. Condensate into condensed water. The heavy oil heated by the heat exchanger 29 is supplied to the heavy oil reforming process through the supply pipe 21, and is reformed at 380 ° C. and 25 MPa in the heavy oil reforming process. The reformed gas and supercritical water are heated in the metal content separation step 2, the metal content is separated at 420 ° C. and 25 MPa, and burned in the combustor 3. The combustion gas drives the gas turbine 4 and then enters the heat recovery unit 5 at about 540 ° C. and about 1 atm. The heat recovery unit 5 is inserted with a normal steam generator and the reaction step 12 and the capture step 13 according to the present invention, and recovers heat by indirect heat exchange with the combustion gas. The combustion exhaust gas that has exited the heat recovery device 5 is subjected to removal of SOx, NOx, and dust by the environmental device 6, and reaches the cooling step 14. The condensed water obtained in the cooling step 14 is stored in the condensed water tank 30 through the drain pipe 28. The stored condensed water is measured by the measuring device 8 for S, N and C, and the amount is obtained. 1.5 times mole of NaOH is supplied to the condensed water tank 30 by the alkali addition device 9 with respect to the measured mole number of S. Further, H ₂ O ₂ of 3 times the number of moles obtained by adding the number of moles of S and the number of moles of C is supplied to the condensed water tank 30 by the oxidant addition device 10. In addition, the alkali to add may be KOH which performs the same function with respect to the impurity treatment in condensed water other than NaOH.
[0020]
Condensed water from the adjusting step 7 constituted by the measuring device 8, the alkali adding device 9, the oxidizing agent adding device 10 and the condensed water tank 30 is pressurized to 25 MPa by the pressure pump 11 and installed in the heat recovery device 5. Sent to the reaction step 12. In the reaction step 12, the condensed water is heated to 380 ° C., and the water becomes supercritical water. Further, H ₂ O _{2 as} an additive becomes H ₂ O and 1 / 2O ₂ , O ₂ reacts with C component dissolved in supercritical water and becomes CO ₂ , and S component becomes SO ₂ . Further, SO ₂ reacts with the additive NaOH to become Na ₂ SO ₄ . All of these substances are completely dissolved in supercritical water in the range of 374 ° C to 410 ° C. The substance that has left the reaction step is introduced into the capture step 13. In the capturing step 13, a filler such as limestone is filled from the filler supply pipe 27. Further, the temperature of the fluid flowing from the reaction process is increased to about 430 ° C. As a result, S compounds such as Na ₂ SO ₄ and SO ₄ dissolved in the supercritical water precipitate on the surface of the limestone, and further react with the limestone to become CaSO _{4 and} are fixed to the limestone. The supercritical water from which impurities have been removed in this step is returned to the heavy oil reforming step 1 through the discharge pipe 22, the pressure control valve 25, and the return pipe 23 and reused.
[0021]
In this embodiment, the condensed water recovered when the reformed fuel obtained by treating the heavy oil with the supercritical water is burned is composed of the adjusting step 7, the pressurizing pump 11, the reaction step 12, the trapping step 13, and the pressure control valve 25. Then, impurities in the condensed water were removed. The results are as follows.
Case 1
Condensed water: S component 3 mol, C component 4.2 mol NaOH addition amount: 4.5 mol H ₂ O ₂ addition amount: 10.8 mol Reaction process: temperature 380 ° C., pressure 25 MPa
Capturing step: temperature 430 ° C., pressure 25 MPa, limestone discharged from the filling pressure control valve 25 S content 0.03 mol, C content 0.002 mol Case 2
Condensed water: S component 3 mol, C component 4.2 mol KOH addition amount: 4.5 mol H ₂ O ₂ addition amount: 10.8 mol Reaction process: temperature 380 ° C., pressure 25 MPa
Capturing step: temperature 430 ° C., pressure 25 MPa, supercritical water discharged from limestone filling pressure control valve 25 S component 0.03 mol, C component 0.002 mol Case 3
Condensed water: S component 3 mol, C component 4.2 mol NaOH addition amount: 3 mol H ₂ O ₂ addition amount: 10.8 mol Reaction process: temperature 380 ° C., pressure 25 MPa
Capture step: temperature 430 ° C., pressure 25 MPa, limestone discharged from the filling pressure control valve 25 S component 0.05 mol, C component 0.002 mol (Example 2)
This embodiment is configured to prevent white smoke in the exhaust gas finally released into the atmosphere and to enhance the cooling effect of the combustion exhaust gas from the heat exchanger 5, and will be described with reference to FIG.
[0022]
The combustion exhaust gas is supplied to the cooling step 14 after the temperature is lowered by the heat recovery device 5 and the exhaust gas heater 108. In the cooling step 14, an absorbing liquid 113 to be described later is injected from the spray device 104, moisture contained in the combustion exhaust gas is cooled, and condensed water 106 containing sulfur oxides and nitrogen oxides is obtained. Further, after removing the mist from the combustion exhaust gas by the mist collector 107, the combustion exhaust gas is heated by the exhaust gas heater 108 so as not to generate white smoke. A part of the condensed water 106 is pressurized by the pump 105, pH is adjusted by the pH adjuster 103, and then supplied to the spray device 104 as the absorbing liquid 113. The other of the condensed water is sent to the adjustment step 7.
[0023]
The spray device 104 is a device that sprays water as fine droplets. For example, a plurality of spray nozzles are installed on a surface perpendicular to the flow direction of the combustion exhaust gas. Due to the gas-liquid contact in the spray tower, the temperature of the combustion exhaust gas is lowered, and the moisture in the combustion exhaust gas present as a gas is condensed into a liquid. Further, SO ₂ in the combustion exhaust gas is absorbed by the absorption liquid adjusted in pH. In order to promote the absorption and improve the efficiency of desulfurization from the combustion exhaust gas, the reaction of absorbing SO ₂ in the combustion exhaust gas into the liquid is promoted. In order to promote the reaction of absorbing SO ₂ in the gas phase into the liquid, the pH of the absorbing liquid is set to 3.8 or higher.
[0024]
On the other hand, H ₂ O ₂ is added in order to completely oxidize the sulfur oxide in the adjustment step 7 and the reaction step 12, but in order to reduce the addition amount, the sulfur oxide is reacted with oxygen in the air in the cooling step 14. To make sulfuric acid. When the pH of the absorbing solution was 2 to 4, the production of dithionic acid, which is a sulfur oxide that was not completely oxidized, was maximized, and dithionic acid was not produced when the pH was 6.0 or higher. Therefore, the pH of the absorbing solution was adjusted to 6.0 or higher. As the pH adjuster used in the absorbent, slaked stone, quicklime, or caustic soda is used.
[0025]
The pH of the absorbing solution is adjusted by checking the pH of the condensed water 106 with the pH meter 101 and supplying the pH adjuster from the pH adjuster supply controller 102 to the pH supplier 103 so that the pH is 6.0 or higher. To control. The adjustment system of the sulfur and nitrogen compound concentration of the absorption liquid is examined by the sulfur and nitrogen compound measuring instrument 114 in the same manner as the pH adjustment. When the concentration exceeds a certain level, the makeup water controller 115 supplies the makeup water to the pH adjuster 103. Supply and control so that pH is 6.0 or more. The amount of condensed water 106 is adjusted by detecting the liquid level with the liquid level gauge 119 and opening and closing the valve 117 with the liquid level controller 118 so as to keep the amount of condensed water constant.
[0026]
In the present embodiment, the heat exchanger 5 that collects condensed water from the combustion exhaust gas, the exhaust gas heater 108, the cooling process 7, the spray device 104, the mist collector 107, the pH adjuster 103, and the pump 105 are configured to contain the condensed water. Impurity removal was performed. The results are as follows.
Case 1
S content in combustion exhaust gas 109: 70ppm
Combustion exhaust gas 109 temperature: 160 ° C
PH of water in spray device 104: 11.4
Absorption liquid 113 temperature: 40 ° C
Absorbent 113 pH: 11.3
pH adjuster: NaOH
Dithionic acid concentration in condensed water 106: 0.5 ppm
S content in exhaust gas heater 108: 30 ppm
Exhaust gas temperature in the exhaust gas heater 108: 90 ° C
Case 2
S content in combustion exhaust gas 109: 70ppm
Combustion exhaust gas 109 temperature: 130 ° C
PH of water in spray device 104: 11.4
Absorption liquid 113 temperature: 40 ° C
Absorbent 113 pH: 11.3
pH adjuster: NaOH
Condensed water 106 dithionic acid concentration: 0.7ppm
S content in the exhaust gas heater 108: 20 ppm
Exhaust gas temperature in the exhaust gas heater 108: 90 ° C
According to the second embodiment, there is an effect that water is efficiently recovered from the combustion exhaust gas of the gas turbine, and the combustion exhaust gas exhausted from the gas turbine does not generate white smoke.
Example 3
This embodiment is configured to supply an appropriate amount of the adjusting agent in the adjusting step 7 and reduce the corrosion rate of the piping in the reaction step 12, and will be described with reference to FIG. Measuring instrument 8 for measuring sulfur oxide (S ₂ O ₃ ²⁻ , SO ₃ ²⁻ , S ₂ O ₆ ²⁻ ), TOC, COD, pH adjuster supplier 9, oxidizer supplier 10 and condensed water tank Corrosion of the reactor can be suppressed by adjusting the supply amount of the condensed water H ₂ O ₂ with a configuration of 32.
[0027]
In the adjustment step 7, the substance that can be oxidized with pH adjustment is analyzed, and an additive and an oxidizing agent are added to the condensed water 30. In order to measure the sulfur concentration and the carbon concentration, the condensed water 30 is agitated by the agitator 31 and collected from the condensed water tank 32. In the condensed water tank 32, the condensed water is stirred by the stirrer 31 to make the aqueous solution concentration uniform. The sulfur oxide measuring device 132 that measures the sulfur content in the condensed water stored in the condensed water tank 30 measures the concentration of sulfur oxide that can be oxidized, such as thiosulfuric acid, sulfurous acid, and dithionic acid, by ion chromatography. The change in pH when each ionic species is oxidized to sulfuric acid is calculated, and the supply amount of the pH adjusting agent is adjusted by the concentration controller 131 so that the pH becomes 7 to 12 after the reaction is completed. To supply. In addition, the amount of H ₂ O ₂ required for oxidation for each ionic species is calculated.
[0028]
The measuring device 8 that measures carbon content measures total organic carbon (TOC). When TOC is measured by the TOC measuring device 133, the hydrogen peroxide supply amount is calculated as an amount of H ₂ O ₂ equivalent to ₂ to 3 times the oxygen amount for oxidizing TOC.
[0029]
Chemical oxygen demand (COD) is used to determine the amount of oxygen supplied to oxidize elements other than carbon. However, the COD measurement is smaller than the theoretically required oxygen amount. A COD measuring device 134 is used for measuring COD. When the COD of sulfurous acid or dithionic acid is measured, the values are 1/8 and 1/4 of the amount of oxygen necessary for actual oxidation. Therefore, the equivalent of 2 to 3 times the amount of H ₂ O ₂ obtained by subtracting the amount of oxygen necessary to completely oxidize the sulfur oxide from the COD value is calculated.
[0030]
The amount of H ₂ O ₂ calculated from sulfur oxide, TOC, and COD is adjusted by the concentration controller 131 and supplied to the condensed water supply pipe 135 by the oxidant addition device 10.
[0031]
In this example, the impurities in the condensed water were dithionic acid, organic matter, and metal ions, and SUS316 piping was used and oxidized at 450 ° C. and 25 MPa using H ₂ O _{2 as} an oxidizing agent and NaOH as a pH adjusting agent. Table 1 shows the concentration of each component in the stock solution, the concentration of each component in the solution after treatment, the corrosion rate, and the presence or absence of pitting corrosion.
[0032]
[Table 1]

[0033]
According to the third embodiment, impurities in the condensed water can be completely oxidized without causing pitting corrosion even when the condensed water containing sulfuric acid is supercritically hydroxylated.
Example 4
This embodiment is configured to reduce the amount of H ₂ O ₂ added to recover and reuse the water after burning the mixed fuel of heavy oil and supercritical water. I will explain.
[0034]
When heavy oil is burned and impurities are collected from the combustion exhaust gas, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, V ₂ O ₅ , metal oxides, etc. are present in the condensed water 106 recovered from the combustion exhaust gas. . These easily form a salt in supercritical water, and can be easily separated and removed in the capturing step 13.
[0035]
A schematic diagram showing a conventional configuration is shown in FIG. In this method, pressure is applied from a tank 321 using a pump 322 and heated by a heat exchanger 323 to be in a supercritical state. It reacts with the oxygen source in the supercritical reactor 324, is cooled and decompressed in the extractor 325, takes out the gas component in the gas-liquid separator 327, and further separated into light oil and water in the drain separator 328. In the separated water, NH ₃ , H ₂ S, cyanide and metals such as sodium, potassium and vanadium ions dissolve in the water. Moreover, since oil remains in water, COD and TOC increase.
[0036]
Table 2 shows the conventional process waste water and the condensed water state of this example.
[0037]
[Table 2]

[0038]
According to the fourth embodiment, it is possible to completely oxidize impurities in the condensed water by treating the easily contained components from the condensed water.
(Example 5)
This embodiment is configured to recover moisture in the combustion exhaust gas that is finally released into the atmosphere and prevent white smoke from being generated. Furthermore, it is configured to increase the power generation efficiency by increasing the water recovery rate, and will be described with reference to FIG.
[0039]
The combustion exhaust gas is supplied to the cooling step 14 after the temperature is lowered by the heat recovery device 5 and the exhaust gas heater 108. In the cooling step 14, the absorbing liquid 113 is jetted from the spray device 104, the moisture contained in the exhaust gas is cooled, and becomes condensed water 106 containing sulfur oxides and nitrogen oxides. Further, after removing the mist from the combustion exhaust gas by the mist collector 107, the combustion exhaust gas is heated by the exhaust gas heater 108 so as not to generate white smoke.
[0040]
The influence of the water recovery conditions for the condensed water recovered from the combustion exhaust gas 109 in the cooling step 14 will be described. Factors affecting the power generation efficiency due to changes in water recovery conditions include: a) change in pressure loss (change in pressure ratio depending on the presence or absence of the cooling step 14), b) heat recovery lower limit temperature (gas temperature in the combustion exhaust pipe 110) C) makeup water temperature and amount (preheating effect by latent heat recovery at the time of water recovery). Table 3 summarizes the water recovery conditions and their effects.
[0041]
[Table 3]

[0042]
By setting the water recovery rate to 100% according to this embodiment, the power generation efficiency can be increased by 0.2%. Furthermore, the amount of makeup water can be reduced. Conventionally, the combustion exhaust gas temperature is raised to prevent the generation of white smoke, but the temperature of the combustion exhaust gas discharged out of the system can be lowered because water is recovered and the dew point is lowered.
[0043]
【The invention's effect】
According to the present invention, in a system in which heavy oil is lightened with supercritical water and burned while mixed, impurities such as sulfur oxides and metal oxides absorbed in warm water recovered from combustion exhaust gas are separated, It can be removed and returned to the supercritical water reactor again to be used for lightening heavy oil, and the amount of water used can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present invention.
FIG. 2 is a diagram showing an embodiment example of a cooling process of the present invention.
FIG. 3 is a diagram showing an embodiment example of an adjustment process of the present invention.
FIG. 4 is a schematic diagram showing a conventional configuration.
[Explanation of symbols]
1 ... Heavy oil reforming process, 2 ... Metal component separation process, 3 ... Combustor, 4 ... Gas turbine, 5 ... Heat recovery device, 6 ... Environmental equipment, 7 ... Adjustment process, 8 ... Measuring instrument, 9 ... Alkali Addition device, 10 ... oxidizer addition device, 11 ... pressurization pump, 12 ... reaction step, 13 ... capture step, 14 ... cooling step, 15 ... heavy oil supply pump, 20 ... piping, 21 ... supply tube, 22 ... Discharge pipe, 23 ... return pipe, 24 ... valve, 25 ... pressure regulating valve, 26 ... filler discharge pipe, 27 ... filler supply pipe, 28 ... discharge pipe, 29 ... heat exchanger, 30 ... condensate tank, 31 ... Stirrer, 32 ... Condensed water tank, 101 ... pH meter, 102 ... pH adjuster supply controller, 103 ... pH adjuster, 104 ... Spray device, 105 ... Condensed water return pump, 106 ... Condensed water, 107 ... Mist Collector, 108 ... Exhaust gas heater, 109 ... Combustion exhaust gas, 110 ... Combustion exhaust gas pipe, 111 ... Combustion exhaust gas, 112 ... Heavy oil heat exchange piping, 113 ... Absorbing liquid, 114 ... Sulfur and nitrogen content measuring machine, 11 5 ... makeup water supply controller, 116 ... part of condensed water, 117 ... valve, 118 ... liquid level controller, 119 ... liquid level gauge, 131 ... concentration controller, 132 ... sulfur oxide measuring device, 133 ... TOC measuring device , 134 ... COD measuring device, 135 ... condensate supply pipe, 321 ... tank, 322 ... pump, 323 ... heat exchanger, 324 ... supercritical reactor, 325 ... extractor, 326 ... pressure reducing valve, 327 ... gas-liquid separation , 328 ... Waste water separator, 329 ... Salt separator, 331 ... Pump (water supply means), 332 ... Compressor (oxygen source supply means), 333 ... Screen process, 334 ... Pressure flotation process, 335 ... Biology Treatment step, 336 ... coagulation sedimentation treatment step, 337 ... sand filtration step.

Claims

In a system that converts heavy oil into light fuel with supercritical water and generates electricity using the resulting reformed fuel, a cooling process that cools the flue gas and collects condensed water, stores the collected condensed water, and adds an alkali or oxidizer A process for adjusting the condensed water under pressure, heating and reacting with supercritical water, and a trapping process for separating and removing impurities in the supercritical water from the reaction process. A system for recovering water from combustion exhaust gas, wherein water is recovered and reused as part of supercritical water used in the light fuel conversion step.

The water recovery system from combustion exhaust gas according to claim 1, wherein one kind of coolant used in the cooling step is heavy oil.

The water recovery system from combustion exhaust gas according to claim 1, wherein the alkali added to the adjustment step is either NaOH or KOH, and the oxidizing agent is H ₂ O ₂ .

4. The system for recovering water from combustion exhaust gas according to claim 3, wherein the amount of alkali added is determined by measuring the S concentration of condensed water discharged from the cooling step to be 1 to 2 moles of the S concentration.

In claim 3, the amount of oxidant added is determined by measuring the S concentration and C concentration of condensed water discharged from the cooling step, and is 2 to 4 times the total number of moles from the combustion exhaust gas. Water recovery system.

4. The system for recovering water from combustion exhaust gas according to claim 3, wherein the pH of the condensed water discharged from the cooling step is measured and the amount of alkali added is adjusted.

4. The system for recovering water from combustion exhaust gas according to claim 3, wherein COD in the condensed water is measured and the amount of oxidant added is 8 to 32 times equivalent to the COD value.

The water recovery system from combustion exhaust gas according to any one of claims 1 to 7, wherein in the capturing step, limestone is filled as a filler.

The combustion according to any one of claims 1 to 8, wherein the cooling step is provided with a spray device for injecting a pH-adjusted absorption liquid and absorbing the SO ₂ in the combustion exhaust gas into the absorption liquid. Water recovery system from exhaust gas.

The water recovery system from combustion exhaust gas according to any one of claims 1 to 9, wherein a step of reacting sulfur oxides with oxygen in the air to form sulfuric acid is added to the cooling step.

The water recovery system from combustion exhaust gas according to any one of claims 1 to 10, wherein a concentration adjustment controller for adjusting the concentration of the supply amount of the pH adjusting agent is attached to the adjustment step.

The water recovery system from combustion exhaust gas according to any one of claims 1 to 11, further comprising a step of heating the exhaust gas again after removing the mist in the combustion exhaust gas cooled in the cooling step. .