JP4128804B2

JP4128804B2 - Fuel reformer

Info

Publication number: JP4128804B2
Application number: JP2002161482A
Authority: JP
Inventors: 慶泉蘇
Original assignee: 荏原バラード株式会社
Priority date: 2002-02-05
Filing date: 2002-06-03
Publication date: 2008-07-30
Anticipated expiration: 2022-06-03
Also published as: JP2003300703A

Description

【０００１】
【発明の属する技術分野】
本発明は、炭化水素系燃料を改質して水素に富む改質ガスを製造する燃料改質器に関し、特に構造が比較的シンプルで製造コストが安価な一体型の燃料改質器に関する。また、本発明は、炭化水素系燃料として都市ガス、ＬＰＧや嫌気性消化ガス等の気体燃料や灯油やガソリン等の液体燃料等のような各種の炭化水素系燃料に対処できる、固体高分子型燃料電池に適した改質ガスを製造する一体型の燃料改質器に関する。
【０００２】
【従来の技術】
近年、地球環境の保全を背景に熱と電気とを併給できる燃料電池コージェネレーションシステムが開発されつつある。該システムでは天然ガス等の炭化水素系燃料を改質装置により水蒸気改質して水素に富む改質ガスを製造し、製造した改質ガスを燃料電池に供給して発電するようになっている。そこで、改質装置はシステム全体の経済性とエネルギー効率にとって重要な開発要素である。
【０００３】
一般に、燃料電池がリン酸型燃料電池の場合には、改質装置は、改質熱を供給する燃焼部、炭化水素を水蒸気との改質反応によって水素とＣＯに改質する改質部、並びに改質ガス中のＣＯを水蒸気との変成反応によって水素とＣＯ２に変成する変成部とを備えている。また、燃料電池が固体高分子型燃料電池の場合には、改質装置は、改質熱を供給する燃焼部、改質部、変成部、並びにＣＯ変成ガス中の残留ＣＯを酸素との選択的酸化反応により除去する選択酸化部とを備えている。改質装置のコンパクト化や熱効率向上を図るために、改質器の各構成部を一体化した一体型改質器が提案されており、例えば多重円筒式改質器や積層平板型改質器等が開示されている。
【０００４】
【発明が解決しようとする課題】
しかしながら、従来の多重円筒型改質器では、高温のバーナー燃焼部と、加熱が必要な高温吸熱反応を行う改質部と、冷却が必要な中低温放熱反応を行う変成反応部及び選択酸化部とが同軸の多重円筒体に配置されているので、構造がかなり複雑で製造コストが高くなるという課題があった。また、従来の多重円筒型改質器では、各部を区画する円筒状隔壁の長さと面積が大きく、且つ各部間における温度差が大きいことから、各部の連結部に発生する熱応力が大きく、また隔壁を通過する熱流が大きいという性質がある。そこで、各部の温度分布が互いに影響し合っていて温度制御が難しく、起動時間も長い等の課題がある。また、従来の積層平板型改質器についても、多重円筒型改質器と基本的に同様な課題を抱えている。
【０００５】
また、従来の改質装置では都市ガスや天然ガスのような気体燃料と、ガソリン、灯油、メタノール等の液体燃料の何れか一方に対処している。即ち、気体燃料に対しては気体燃料の予熱や水蒸気との混合機構が要求される。他方、液体燃料では、液体燃料の気化機構が必要となる。そこで、従来の改質装置では気体燃料用と液体燃料用とを別々に用意することで、顧客の需要に応えようとしていた。
【０００６】
しかし、気体燃料と液体燃料とは供給事業者が別系列であると共に、揮発油税のような課税に対しても異なる取扱いがされている。そこで、燃料電池の使用者においては、改質装置が気体燃料と液体燃料の何れにも対処できれば、経済環境の時々の変動に応じて最適な燃料を利用できるという利点がある。また、気体燃料用と液体燃料用の改質装置を別々に製造する場合に比較して、気体燃料と液体燃料の両方に適用できる改質装置を製造する場合には、量産効果により改質装置の製造コストが低下する可能性もある。
【０００７】
本発明は上記した課題を解決するもので、第１の目的は、構造が比較的シンプルで製造コストが安価な燃料改質器を提供することである。第２の目的は、熱応力の発生が少なくて耐久性に優れる燃料改質器を提供することである。第３の目的は、燃料改質器各部の最適温度分布の制御が容易で熱効率が高く、且つ起動時間も短い燃料改質器を提供することである。第４の目的は、気体燃料と液体燃料の両方を改質できる燃料改質器を提供することである。
【０００８】
【課題を解決するための手段】
第１の目的を達成する本発明の燃料改質器は、図１に示すように、燃料が燃焼する燃焼室５Ａと、該燃焼室５Ａの外周面側に設けられると共に、環状に改質触媒を充填した改質部７を有する高温ユニット２と、高温ユニット２と連結される側に設けられると共に、筒状又は環状に変成触媒を充填した変成部（２１、２６）と、高温ユニット２と連結される側とは反対側に設けられると共に、筒状又は環状に選択酸化触媒を充填した選択酸化部３６を有する中低温ユニット３と、高温ユニット２の改質部を通過した改質ガスを、中低温ユニット３の変成部側に供給する連結流通管１９と、連結流通管１９によって連結される高温ユニット２と中低温ユニット３を一体に収容する容器１３とを備えている。
【０００９】
燃焼室５Ａは、典型的にはバーナー４を内部に有し、該バーナー４で燃料を燃焼させる。さらに典型的には、該バーナー４は燃焼室５Ａの中心軸に備えられている。
このように構成された燃料改質器においては、高温ユニット２では、改質部７の温度が、例えば起動時の室温程度の状態から定常運転時の運転温度まで昇温する。中低温ユニット３では変成部（２１、２６）の温度が、起動時の室温程度の状態から定常運転時の変成部温度まで昇温し、選択酸化部３６の温度が、起動時の室温程度の状態から定常運転時の選択酸化部温度まで昇温する。このように定常状態での稼動温度によって、高温ユニット２と中低温ユニット３に区分して、連結流通管１９によって改質ガスを改質→変成→選択酸化という処理の流れに沿って流通するようにしていると共に、容器１３にて一体に収容しているので、構造が簡単で製造コストが安価になる。好ましくは、高温ユニット２と中低温ユニット３の軸線は共通とし、断面形状は円形若しくは長方形（正方形を含む）とすると、顧客の設置場所に合わせた形状の燃料改質器が提供される。特に、円形とするとガスの流れが一様となり、製造に必要な材料も少なくて済む。長方形、特に正方形とすると、設置が容易になる。
【００１０】
好ましくは、本発明の燃料改質器において、さらに、高温ユニット２及び中低温ユニット３の外壁と容器１３の内壁との間隙に形成された改質添加水流路４０と、該改質添加水流路４０の中低温ユニット３の高温ユニット２と連結される側とは反対側に設けられた改質添加水注入口４１とを備える構成とするとよい。このように構成すると、定常運転時には高温ユニット２及び中低温ユニット３の外壁を通じて、改質添加水流路４０を流れる改質添加水と改質ガスとの熱交換が行われ、熱効率が高まる。
【００１１】
好ましくは、さらに第４の目的を達成するために、本発明の燃料改質器において、さらに、高温ユニット２に改質原料を供給する改質原料供給路５０、改質添加水流路４０並びに改質原料供給路５０を互いに連通する混合室４４とを備える構成とすると、改質添加水流路４０にて過熱蒸気状態となった改質添加水を用いて、混合室４４内の改質原料に対して、改質部７での改質反応を円滑に行うための処理がなされる。即ち、改質原料が液体燃料の場合には燃料の気化が行われ、気体燃料の場合には燃料の予熱が行われる。
【００１２】
好ましくは、さらに第３及び第４の目的を達成するために、本発明の燃料改質器において、さらに、高温ユニット２に改質原料を供給する改質原料供給路５０と、中低温ユニット３を経由せず、高温ユニット２に直接改質添加水を供給する第２改質添加水流路４５と、改質添加水流路４０、改質原料供給路５０並びに第２改質添加水流路４５を互いに連通する混合室４４とを備える構成とするとよい。
【００１３】
このように構成された燃料改質器の起動時においては予熱用熱媒としての改質添加水を第２改質添加水流路４５より供給し、燃焼ガスとの熱交換により混合室４４にて、改質添加水の蒸気を発生させる。この発生した蒸気を改質添加水流路４０に逆流させることにより、中低温ユニット３を予熱して、中低温ユニット３の予熱に窒素ガスのような熱媒を用いることなく予熱することで、起動時間を短縮させる。また、中低温ユニット３を改質ガス導入前に予熱しておくことで、改質ガス導入時に中低温ユニット３の変成触媒層や選択酸化触媒層における水の結露を防ぎ、よって触媒寿命を向上させることができる。
また、燃料改質器の定常運転時において、改質添加水の総流量を変えることなく、改質添加水流路４０と第２改質添加水流路４５の各水量の比率を調整させるだけで、各部の温度を安定的に制御できる。
【００１４】
第３の目的を達成する本発明の燃料改質器は、さらに、高温ユニット２と中低温ユニット３との連結部間隙に設けられたバッフル板１８と、高温ユニット２と中低温ユニット３との対向面に設けられる熱交換部２４であって、高温ユニット２から中低温ユニット３に送られる改質ガスと改質添加水との熱交換を行う熱交換部２４とを備える構造とすると、熱交換部２４において高温ユニット２及び中低温ユニット３の外壁を通じて、改質添加水流路４０を流れる改質添加水と改質ガスとの熱交換が行われ、改質添加水を蒸発させて過熱すると共に、燃料改質器内部の温度分布が適切なものとなる。
【００１５】
第２及び第３の目的を達成する本発明の燃料改質器は、連結流通管１９が、該連結流通管１９の軸方向に伸縮する伸縮部材を有する構造とすると、起動時のような冷えた状態と定常運転時のように昇温した状態とで、高温ユニット２、中低温ユニット３並びに容器１３との間で生じる熱膨張による歪を連結流通管１９の伸縮によって吸収でき、起動／運転を繰り返しても熱応力の影響が少なくて済む。伸縮部材には、ベローズのように波形断面を有するものと、ダイヤフラムのように曲げ変形が容易な部材とが含まれる。さらに、伸縮部材の表面積は直管に比較すると広いため、管内を流れる改質ガスと管外を流れる改質添加水との熱交換が効率的に行える。
【００１６】
本発明の燃料改質器において、高温ユニット２は上側に配置され、中低温ユニット３は高温ユニット２の下側に配置されると、改質水添加流路が設けられている場合には、水から水蒸気への相変化と、水と水蒸気の比重の差と重力方向が一致して自然になる。また、本発明の燃料改質器において、高温ユニット２は下側に配置され、中低温ユニット３は高温ユニット２の上側に配置されると、例えば燃料改質器に対する水の供給や改質原料の供給に既設配管を利用する場合には、倒立取付けとすることで、燃料改質器の据付施工面で便利な場合もある。
【００１７】
好ましくは、本発明の燃料改質器において、変成部は、高温ユニット２側に設けられると共に、筒状又は環状に第１の変成触媒を充填した第１変成部２１と、選択酸化部３６側に設けられると共に、筒状又は環状に第２の変成触媒を充填した第２変成部２６とを有する構成とすると、変成部における温度分布が最適化されると共に、変成反応に伴う発熱の除熱が容易になる。また、定常運転時においては、第１変成部２１が第２変成部２６に比較して高温になるため、この定常時の温度にて変成反応が効率良く進行するように、第１の変成触媒と第２の変成触媒の組成を適切に選択できる。
【００１８】
好ましくは、本発明の燃料改質器において、例えば図７に示すように、さらに第２変成部２６は、中低温ユニット３の外壁と同軸に設けられた内円筒体２９と、中低温ユニット３の外壁と同軸であって、該内円筒体２９の外周側に設けられた中円筒体３０とを備え、内円筒体２９の内周面によって第１変成部２１を通過した改質ガスのガス導入流路３１を形成し、内円筒体２９の外周面と中円筒体３０の内周面によって第２変成部２６の触媒充填層２５を形成し、中円筒体３０の外周面と中低温ユニット３の内周面によってガス導出流路３２を形成する構成とするとよい。即ち、第１変成部２１を通過した改質ガスはガス導入流路３１を通過し、次に触媒充填層２５を通過し、さらにガス導出流路３２を通過して選択酸化部３６へ導かれる。
【００１９】
好ましくは、本発明の燃料改質器において、例えば図７に示すように、さらに第２変成部２６は、ガス導入流路３１と第２変成部２６の触媒充填層２５とを連通すると共に、内円筒体２９の選択酸化部３６側に設けられた第１の開口部３３と、第２変成部２６の触媒充填層２５とガス導出流路３２とを連通すると共に、中円筒体３０の第１変成部２１側に設けられた第２の開口部２８と備える構成とするとよい。即ち、第１変成部２１を通過した改質ガスは下向流でガス導入流路３１を通過し、第１の開口部３３で折り返して、上向流で触媒充填層２５を通過する。触媒充填層２５を出た改質ガスは、第２の開口部２８にて折り返して、下向流でガス導出流路３２を通過して選択酸化部３６へ導かれる。
【００２０】
好ましくは、本発明の燃料改質器において、例えば図１及び図７に示すように、変成部（２１、２６）と選択酸化部３６との間隙にバッフル板３８を設け、該バッフル板３８の中央開口部の内側に選択酸化用空気の導入口５８を配置すると、変成部にて変成された改質ガスと選択酸化用空気とが適切に混合されて、選択酸化部３６での選択酸化反応が効果的に進行する。
【００２１】
好ましくは、本発明の燃料改質器において、例えば図７に示すように、選択酸化部３６は、中心部近傍に変成部（２１、２６）から送られる改質ガスが通過しないように構成された筒体状中空部３６Ｂが設けている構成とすると、改質ガスの流れる量が多くなりがちな中心部近傍の流れが抑止されるので、選択酸化部３６の周縁部に改質ガスが均一に流れ、選択酸化反応が均一に進行する。そこで、選択酸化部３６で充填される選択酸化触媒の量が最適化されると共に、温度分布も最適化される。
【００２２】
好ましくは、本発明の燃料改質器において、例えば図８に示すように、中低温ユニット３は、高温ユニット２側に設けられると共に、筒状又は環状に第１の変成触媒を充填した第１変成部２１と、筒状又は環状に第２の変成触媒を充填した第２変成部２６Ａとを有する変成部（２１、２６Ａ）を備え、第２変成部２６Ａが選択酸化部３６Ａに対して同軸円筒状に位置する構成とすると、第２変成部２６Ａと選択酸化部３６Ａが同心円状に配置されて改質器全体がコンパクトになる。
【００２３】
好ましくは、本発明の燃料改質器において、例えば図８に示すように、第２変成部２６Ａは、中低温ユニット３の外壁と同軸に設けられた内円筒体２９Ａと、中低温ユニット３の外壁と同軸であって、内円筒体２９Ａの外周側に設けられた中円筒体３０Ａとを有している。そして、第２変成部２６Ａの触媒充填層２５Ａは、内円筒体２９Ａの外周面と中円筒体３０Ａの内周面によって形成された空間に設けられている。選択酸化部３６Ａの選択酸化触媒充填層３５Ａは、中円筒体３０Ａの外周面と中低温ユニット３の内周面によって形成された空間に設けられている。ガス導入流路３１Ａは、第１変成部２１と第２変成部２６Ａとの対向部に形成されたもので、第１変成部２１を通過した改質ガスを第２変成部２６Ａに流入させる。ガス導出流路３２Ａは、第２変成部２６Ａの底面側と、選択酸化部３６Ａの第１変成部２１対向部とを連絡する管路７０Ａとで形成され、第２変成部２６Ａを通過した改質ガスを選択酸化部３６Ａに送る。
【００２４】
このように構成された装置においては、第１変成部２１を通過した改質ガスはガス導入流路３１Ａを通過し、次に第２変成部２６Ａを通過し、さらにガス導出流路３２Ａを通過して選択酸化部３６Ａへ導かれる。また、選択酸化部３６Ａは第２変成部２６Ａを中心部として環状に位置しているので、改質ガスの流れる量が多くなりがちな改質器中心部近傍の流れが抑止され、選択酸化部３６Ａの周縁部に改質ガスが均一に流れ、選択酸化反応が均一に進行する。この結果、選択酸化部３６Ａに充填される選択酸化触媒の量が最適化されると共に、温度分布も最適化される。
【００２５】
好ましくは、本発明の燃料改質器において、例えば図８に示すように、さらに、第１変成部２１と第２変成部２６Ａとの対向部に設けられたバッフル板２７Ａを有し、ガス導入流路３１Ａは、バッフル板２７Ａ、中円筒体３０Ａの内周面、並びに内円筒体２９Ａの外周面によって形成される構成とするとよい。好ましくは、バッフル板２７Ａは円環状とし、円環の中心部にガス分散板３４Ａを設けると、第２変成部２６Ａに改質ガスが均一に流れ、変成反応が均一に進行する。
【００２６】
好ましくは、本発明の燃料改質器において、例えば図８に示すように、ガス導出流路３２Ａは、中円筒体３０Ａの底面３９、内円筒体２９の内周面、並びに内円筒体２９Ａの内周面と選択酸化部３６Ａとを連絡する管路７０Ａによって形成されると、コンパクトな形状の改質器に対して、ガス導出流路３２Ａが効果的に配置される。好ましくは、選択酸化用空気の導入口５８が、内円筒体２９の中円筒体３０Ａの底面３９側に位置する第１開口部３３Ａの内側に配置されると、変成部（２１、２６Ａ）にて変成された改質ガスと選択酸化用空気とが適切に混合されて、選択酸化部３６Ａでの選択酸化反応が効果的に進行する。
【００２７】
好ましくは、本発明の燃料改質器において、容器１３の外周に真空断熱層６０を備えると、改質器全体がコンパクトになると共に、高温ユニット２、中低温ユニット３、改質添加水流路４０を流れる改質添加水からの熱損失が少ないので、改質器の熱効率が向上する。好ましくは、真空断熱層６０を形成する壁面を反射率の高い材料、例えば銀メッキやアルミメッキにて形成すると、熱伝導に加えて熱ふく射も減少させることができる。
【００２８】
第３及び第４の目的を達成する本発明の燃料改質器は、例えば図１に示すように、燃料が燃焼する燃焼室５Ａと、該燃焼室５Ａの外周面側に設けられると共に、改質触媒を充填した改質部７を有する高温ユニット２と、高温ユニット２の改質部７を通過した改質ガスを変成する変成部（２１、２６）と、前記変成部で変成された改質ガスを選択酸化する選択酸化部３６を有する中低温ユニット３と、改質添加水が中低温ユニット３にて熱交換可能に配置されると共に、高温ユニット２に対して前記改質添加水を供給する改質添加水流路４０と、中低温ユニット３を経由せず、高温ユニット２に直接改質添加水を供給する第２改質添加水流路４５と、高温ユニット２に改質原料を供給する改質原料供給路５０と、改質添加水流路４０、第２改質添加水流路４５並びに改質原料供給路５０を互いに連通する混合室４４とを備えている。
【００２９】
このように構成された燃料改質器の起動時においては予熱用熱媒としての改質添加水を第２改質添加水流路４５より供給し、燃焼ガスとの熱交換により混合室４４にて、改質添加水の蒸気を発生させる。この発生した蒸気を改質添加水流路４０に逆流させることにより、中低温ユニット３を予熱して、中低温ユニット３の予熱に窒素ガスのような熱媒を用いることなく予熱することで、起動時間を短縮させる。また、中低温ユニット３を改質ガス導入前に予熱しておくことで、改質ガス導入時に中低温ユニット３の変成触媒層や選択酸化触媒層における水の結露を防ぎ、よって触媒寿命を向上させることができる。
また、燃料改質器の定常運転時において、改質添加水の総流量を変えることなく、改質添加水流路４０と第２改質添加水流路４５の各水量の比率を調整させるだけで、各部の温度を安定的に制御できる。
【００３０】
【発明の実施の形態】
以下、本発明による改質器の概略構成を示す断面図を用いて本発明の実施の形態を説明する。
図１は、本発明による燃料改質器の第１の実施形態を示す縦断面図である。図において、改質器１は高温ユニットとしての改質器上部２と、中低温ユニットとしての改質器下部３を備えている。改質器上部２は、燃料を燃焼させるバーナー４と、バーナー４と同軸に配置された燃焼円筒体５と、改質触媒充填層６を収容した円環体状の改質部７を有している。バーナー４は、燃焼円筒体５のほぼ中心軸上に設けられている。改質触媒充填層６に用いる改質触媒は、改質反応を促進するものであれば何でもよく、例えば触媒の種類としてＮｉ系改質触媒やＲｕ系改質触媒などが用いられる。また、改質触媒の形状として粒状、円柱状、ハニカム状やモノリス状などが挙げられる。なお、バーナー４の詳細に関する図示は省略している。
【００３１】
燃焼室５Ａは、燃焼円筒体５によって周壁が形成されている。燃焼円筒体５と改質部７との間隙には、燃焼ガス流路１０とバッフル板１１と出口１２が設けられている。隔壁１５は、燃焼ガス流路１０と改質ガス流路１６とを隔離するもので、耐熱性の高い金属材料等で形成されている。断熱材１４は、燃焼室５Ａと隔壁１５の間に設けられるもので、改質部７を出た改質ガスと燃焼ガスとの間の熱伝達を抑制する。バッフル板１１は、燃焼ガス流路１０での燃焼ガスの流れ分布を均一化させるもので、その構造は円環状で、多数の孔が形成されている。
【００３２】
改質器下部３は、第１変成触媒充填層２０を収容した円筒体状第１変成部２１と、第２変成触媒充填層２５を収容した円筒体状第２変成部２６と、選択酸化触媒充填層３５を収容した円筒体状選択酸化部３６とを備えている。第１変成触媒充填層２０に用いる第１変成触媒として、例えばＦｅ−Ｃｒ系の高温変成触媒やＰｔ系の中高温変成触媒などがある。第２変成触媒充填層２５に用いる第２変成触媒として、例えばＣｕ−Ｚｎ系低温変成触媒やＰｔ系低温変成触媒などがある。第１変成触媒充填層２０と第２変成触媒充填層２５に用いられる触媒の形状としては、粒状、円柱状、ハニカム状やモノリス状などが挙げられる。
【００３３】
選択酸化触媒充填層３５に用いる選択酸化触媒は、ＣＯに対する選択酸化性が高いものであれば何でもよく、例えばＰｔ系選択酸化触媒、Ｒｕ系選択酸化触媒やＰｔ−Ｒｕ系選択酸化触媒などがある。選択酸化触媒充填層３５に用いられる触媒の形状として粒状、円柱状、ハニカム状やモノリス状などが挙げられる。
【００３４】
連結流通管１９は、改質器上部２の底面１７と改質器下部３の上面２３を連結するもので、例えば連結流通管１９の軸方向に伸縮するコルゲート形伸縮管を用いる。ここで、改質器上部２は円筒状の筒体にて周縁が囲われており、底面１７は改質器上部２に対してバケツ状の底板状に設けられると共に、中央部には連結流通管１９に通じる開口部を有している。改質器下部３は円筒状の筒体にて周縁が囲われており、上面２３は改質器下部３に対して蓋状に設けられると共に、中央部には連結流通管１９に通じる開口部を有している。底面４３は改質器下部３に対してバケツ状の底板状に設けられると共に、中央部には改質ガス導出管５５に通じる開口部を有している。
【００３５】
連結流通管１９にコルゲート形伸縮管を用いる場合には、伸縮管の軸方向の変形によって改質器上部２と改質器下部３の熱伸縮を吸収可能なので、底面１７と上面２３には剛性の高い材料を用いても良い。また連結流通管１９の底面１７と上面２３に対する取付け位置は中央部に限らず、周縁部でもよく、また複数の連結流通管１９を底面１７と上面２３に設けても良い。連結流通管１９の管路部分に直管を用いる場合には、底面１７と上面２３の曲げ変形によって改質器上部２と改質器下部３の熱伸縮を吸収可能するために、連結流通管１９の底面１７と上面２３に対する取付け位置は中央部とすると共に、底面１７と上面２３には改質器上部２、改質器下部３の他の部分と同材質の鋼板を用いても良い。なお、底面１７と上面２３には、コルゲート成形を施せば、さらに曲げ変形が容易になり好ましい。このようにすると、連結流通管１９として伸縮性を有しない通常のパイプを用いることもできる。
【００３６】
容器１３は、連結流通管１９によって連結された改質器上部２と改質器下部３を一体に収容する円筒体で、底面には第１改質添加水注入口４１と改質ガス導出管５５が設けられている。容器１３は、円筒状の改質器上部２と改質器下部３に対して同軸に設けられる。断熱層６０は、容器１３の外周及び改質器上部２の上面に設けられるもので、用いる断熱層としては、例えば真空断熱層が好適である。ガス分散板２２は、改質下部上面２３と第１変成触媒充填層２０の間隙に形成された空間に設けられるもので、連結流通管１９から流れてくる改質ガスが均一に第１変成触媒充填層２０に流れるように多孔板が用いられる。ガス分散板３７は、第２変成触媒充填層２５の底面と選択酸化触媒充填層３５の間隙に形成された空間であって、円環状バッフル板３８の下方に設けられるもので、円環状バッフル板３８の中央開口部から流れてくる変成ガスが均一に選択酸化触媒充填層３５に流れるように多孔板が用いられる。
【００３７】
第１改質添加水流路４０は、改質器上部２の外壁及び改質器下部３の外壁と、容器１３の内壁との間隙に形成されるもので、ここでは改質器上部２と改質器下部３が容器１３と同軸に設けられた円筒であるため、断面円環状空間となっている。また、第１改質添加水流路４０は、パイプにて改質器上部２と改質器下部３を貫通すると共に、熱交換できる管材料にて形成されていてもよい。第１改質添加水注入口４１は、第１改質添加水流路４０の改質器下部３側の下端に設けられている。第１改質添加水注入流路６６は、流量調整弁６４と第１改質添加水注入口４１を経由して、第１改質添加水流路４０に改質添加水を供給する管路である。ドレン電磁弁６３は、起動時に開とされて第１改質添加水流路４０を改質添加水又は水蒸気が逆流することを可能とし、定常運転時には閉されて、第１改質添加水流路４０に供給された改質添加水が外部に洩れないようにする。
【００３８】
混合室４４は、改質器上部２の上端に設けられるもので、第１改質添加水流路４０、第２改質添加水流路４５、改質原料流路５０並びに改質部入口ガス流路８が連通しており、定常運転時には改質添加水と改質原料が供給されて、改質添加水と改質原料の混合されたガスを改質部７に送る。第２改質添加水流路４５は、混合室４４の上方に該混合室４４と連通されるように設けられているもので、例えば円環状をしている。第２改質添加水流路４５には、分散板４６と注入口４７が設けられ、第２改質添加水注入流路６７に設けられた流量調整弁６５を介して改質添加水が供給される。改質原料供給路としての改質原料流路５０は、第２改質添加水流路４５の下方であって、混合室４４に連通されるように設けられている円環状の流路である。改質原料流路５０は、分散板５１と注入口５２が設けられる管路である。
【００３９】
円環状バッフル板１８は、改質器上部底面１７と改質下部上面２３との間隙にが設けられている。バッフル板１８は、第１改質添加水流路４０の流れを邪魔して、連結流通管１９側に改質添加水の流れを導くことで、改質添加水の改質器上部底面１７と改質下部上面２３との熱交換を効率良くさせている。熱交換部２４は、改質器上部底面１７、改質下部上面２３、バッフル板１８並びに連結流通管１９によって形成される円環状の空間で、改質ガスと第１改質添加水との熱交換が行われる。
【００４０】
改質ガス導出管５５及び選択酸化用空気導入管５７は、改質器下部３の底面４３に二重管状に設けられている。選択酸化用空気導入口５８は、選択酸化用空気導入管５７の第２変成触媒充填層２５と選択酸化触媒充填層３５との間隙側に設けられた開口部で、円環状バッフル板３８の中央開口部の内側に設置される。電磁弁６２は、改質ガス導出管５５の改質ガス出口に設けられたもので、起動時には閉にされると共に、定常運転時には開にされる。
【００４１】
次に、本発明の燃料改質器の運転方法について説明する。図２は図１の装置における起動時の運転手順を説明する流れ図である。図３は図１の装置における起動時の予熱状態、図４は改質原料の供給開始状態、図５は第１改質添加水の供給開始状態を説明する縦断面図である。なお、図３乃至図５において、弁６２、６３、６４、６５が閉じているときは黒塗りとし、開いているときは白抜きとしている。
【００４２】
まず起動時における運転方法を説明すると、燃焼空気をバーナー４に送りバーナー４と燃焼円筒体５と燃焼ガス流路１０をプレパージして、点火装置を作動すると同時にバーナー燃料の供給を開始し、バーナー着火を行う（Ｓ１００）。バーナー着火が確認されたら、第２改質添加水注入口４７より起動時熱媒としての第２改質添加水を注入し始める（図３参照）。着火後高温の燃焼ガスが、燃焼円筒体５の底部で折り返し、燃焼ガス流路１０を通過しながら改質触媒充填層６を予熱すると共に、第２改質添加水流路４５と混合室４４を流過する起動時熱媒としての第２改質添加水を蒸発し過熱する。起動時には改質ガス出口の電磁弁６２を閉に、第１改質添加水流路のドレン電磁弁６３を開にしているので、発生した過熱蒸気が第１改質添加水流路４０を逆流し、改質器下部３を予熱する（Ｓ１０２）。このように改質器下部３を改質ガス導入前に導入改質ガスの露点以上に予熱しておくことで改質ガス導入時触媒層における水の凝縮を防ぎ、よって触媒寿命を向上させることができる。そして、改質触媒充填層６の入口温度が所定温度に到達したか判断し（Ｓ１０４）、所定温度に到達するまで改質器下部３の予熱を継続する。この改質触媒充填層６の入口温度に対する所定温度は、改質する燃料の種類によって異なるが、例えば４５０〜５５０℃の範囲が好ましい。
【００４３】
改質触媒充填層６の入口温度が所定温度に到達したら、改質ガス出口電磁弁６２を開に、第１改質添加水流路のドレン電磁弁６３を閉に切り替える（Ｓ１０６）。そして、燃料注入口５２と選択酸化用空気導入口５８より定格負荷時の３０〜５０％程度の改質原料としての燃料及び選択酸化用空気をそれぞれ供給し、燃料の改質を開始する（Ｓ１０８；図４参照）。
【００４４】
燃料の改質が始まると、後述のように変成反応及び選択酸化反応が発熱反応なので、第１変成触媒充填層２０と第２変成触媒充填層２５と選択酸化触媒充填層３５とが自らの反応発熱によって昇温する。そして、定常運転に移行するために律速となる触媒層の温度、例えば図１の装置においては、昇温に最も時間がかかる触媒層としての第２変成触媒充填層２５の入口温度が所定温度に到達したか判断する（Ｓ１１０）。第２変成触媒充填層２５の入口温度が所定温度に到達まで、第２改質添加水による燃料の改質を継続する。第２変成触媒充填層２５の入口温度に対する所定温度は、例えば第２変成触媒としてＣｕ−Ｚｎ系低温変成触媒を用いる場合には、１８０〜２２０℃の範囲が好ましい。
【００４５】
第２変成触媒充填層２５の入口温度が所定温度に到達したら、第１改質添加水注入口４１より第１改質添加水の注入を開始する（Ｓ１１２）と共に、燃料及び選択酸化用空気の導入量を定格流量まで徐々に増加させて、起動状態を終了して定常状態に移行する（図５参照）。また、改質ガス導出管５５の出口より排出された改質ガスをバーナー４に導き、バーナー燃料として利用することができる。本発明の燃料改質器の起動時の運転として、燃料改質器の各触媒充填層を予熱する工程を設けることにより、起動時間を短縮し起動性を改善することができる。また、本発明によれば改質器の予熱に改質添加水を熱媒として用い、従来品のように窒素等の熱媒を用いる必要がないため、燃料改質器を各所に分散配置する場合の熱媒確保が容易になる。
【００４６】
次に、本実施の形態における燃料改質器の定常運転時における運転状態を説明する。ここでは、第１改質添加水、第２改質添加水並びに改質原料が改質器上部２や改質器下部３の各部で、どのような条件で処理されて行くかを、図１と図５を参照して説明する。第１改質添加水注入口４１より注入される第１改質添加水は、改質器下部３の内部を流れる改質ガスと対向流で第１改質添加水流路４０を流過する。第１改質添加水流路４０を流れる第１改質添加水は、選択酸化部３６、第２変成部２６及び第１変成部２１を冷却すると同時に蒸発し、熱交換部２４にて改質部７を出た高温の改質ガスによって過熱され、混合室４４に導かれる。燃料注入口５２より注入される改質原料は、灯油など液体燃料の場合には混合室４４にて第１改質添加水の過熱蒸気によって気化され、都市ガスなど気体燃料の場合には予熱される。ここで、混合室４４に入る第１改質添加水過熱蒸気の温度は、例えば４００〜６００℃の範囲にすることができるので、過熱蒸気は燃料の気化又は予熱の熱源として十分に高い能力を有する。
【００４７】
一方、第２改質添加水注入口４７より注入される第２改質添加水は、第２改質添加水流路４５を流過しながら燃焼ガスによって加熱されて蒸発し、混合室４４にて第２改質添加水及び改質原料の混合ガスと合流し、改質部入口ガス流路８を経て改質触媒充填層６に導かれる。
改質触媒充填層６において主に燃料の水蒸気改質反応が行われる。例えば改質原料がメタンの場合、次式による水蒸気改質反応が行われる。
ＣＨ_４＋Ｈ_２Ｏ→ＣＯ＋３Ｈ_２・・・（１）
【００４８】
炭化水素の水蒸気改質反応は吸熱反応なので、反応温度が高いほど炭化水素の改質率が高く反応速度も速い。しかし、温度をあまり高くすると改質器材料の耐熱仕様に対する要求が厳しくなり、また、改質器の放散熱増大などで熱効率が下がる傾向がある。そこで、改質触媒充填層６の温度分布をガスの流れ方向にて例えば５５０〜８００℃にし、改質原料の種類によって最適の温度分布をさらに限定することができる。また、反応にかかわる水蒸気の添加量は多い程改質率が高くなるが、水蒸気を発生するための熱量の増加で熱効率が低下するので、Ｓ／Ｃとして例えば２．２〜３．５の範囲が好適である。なお、改質触媒充填層６への改質反応熱の供給は、燃焼室５Ａでのバーナー燃料の燃焼熱を熱源として、燃焼円筒体５からの熱輻射と、燃焼ガス流路１０を流過する燃焼ガスからの熱伝達とによって行われる。
【００４９】
改質部７を出た改質ガスが熱交換部２４にて減温された後、第１変成部２１並びに第２変成部２６に導かれ、下式の変成反応が行われる。
ＣＯ＋Ｈ_２Ｏ→ＣＯ_２＋Ｈ_２・・・（２）
この変成反応は発熱反応なので、反応温度を低くすれば、有利な点として変成後の改質ガスのＣＯ濃度が低くなる点があり、不利な点として反応速度が遅くなる点がある。
【００５０】
そこで、本実施形態では比較的反応温度の高い第１変成部２１と、反応温度の低い第２変成部２６とを設け、第１変成部２１にて反応速度を早くし、第２変成部２６にて改質ガスのＣＯ濃度を低くすることで、総合的な変成反応の効率を高めている。第１変成触媒充填層２０の温度分布は、例えばガスの流れ方向にて５００〜２８０℃、好ましくは４５０〜３００℃にし、第２変成触媒充填層２５の温度分布は、例えばガスの流れ方向にて２８０〜１７０℃、好ましくは２５０〜１９０℃にするのがよい。各部における改質ガスのＣＯ濃度は、第１変成触媒充填層２０の入口で１０％程度、第２変成触媒充填層２５の入口で３〜５％程度、第２変成触媒充填層の出口で０．３〜１％程度である。このように各変成触媒充填層の温度分布を最適化して変成後改質ガス中の残留ＣＯ濃度を低くすると同時に、変成触媒全体の充填量を少なくし、改質器のコンパクト化と低コスト化を図ることができる。
【００５１】
第２変成部２６を出た改質ガスは選択酸化部３６に導かれ、選択酸化用空気導入口５８より導入された選択酸化用空気との間で下式のＣＯ選択酸化反応が行われる。
ＣＯ＋（１／２）Ｏ_２→ＣＯ_２・・・（３）
選択酸化用空気中の酸素は、反応式（３）により改質ガス中のＣＯを酸化して除去する他に、改質ガス中の水素をも酸化し消費するので、改質器の水素製造効率、即ち熱効率を高くする上で酸素と水素との酸化反応を抑制することが重要である。
【００５２】
本実施形態では、第２変成部２６と選択酸化部３６との空隙に円環状バッフル板３８を設け、バッフル板３８の中央開口部に選択酸化用空気導入口５８を配置することで改質ガスと選択酸化用空気とを均一混合させている。また、選択酸化触媒充填層３５の温度分布は、例えばガスの流れ方向にて２００〜１００℃、好ましくは１５０〜１１０℃にしている。選択酸化用空気の導入量は、選択酸化後改質ガスの残留ＣＯ濃度が例えば１００ｐｐｍ以下、好ましくは１０ｐｐｍ以下となるように決定すればよい。改質器の水素製造効率を高めるには、選択酸化用空気中の酸素と選択酸化部３６に導入される改質ガス中のＣＯとのモル比（Ｏ_２／ＣＯ）として、例えば１．２〜３．０の範囲が望ましく、１．２〜１．８の範囲がより望ましい。
【００５３】
このように選択酸化触媒充填層３５の温度分布を最適化することと、改質ガスと選択酸化用空気との混合をよくすることにより、選択酸化後改質ガスのＣＯ残留濃度を低減すると共に、水素の消費を抑制して改質器の熱効率を改善することができる。
【００５４】
なお、第１の実施形態では上述のように選択酸化部３６を１段としているが、選択酸化部３６を２段にして、例えば図１に示す選択酸化部３６の下方に第２の選択酸化部を設けてもよく、また、改質器７の下流に第２の選択酸化器を設けることもできる。
【００５５】
また、選択酸化部３６を出た選択酸化後改質ガスは改質ガス導出管５５の出口より得られるが、得られた改質ガスを燃料電池に供して発電することができる（燃料電池の詳細に関する図示は省略している）。一般に、炭化水素の改質ガスを燃料とする燃料電池発電の場合、改質ガス中の水素の７０〜８０％が消費され、残りの水素がアノードオフガスとして排出される。第１の実施形態によれば、燃料電池のアノードオフガスをバーナー燃料として用いることができる。
【００５６】
また、上記実施の形態においては、バーナー４において、定常運転時のバーナー燃料をアノードオフガスだけでまかなうアノードオフガス専焼方式か、又はアノードオフガスとあわせ補助燃料として改質原料を供給する混焼方式を用いる構成としてもよい。バーナー４による燃焼で発生した燃焼ガスは下向流で燃焼円筒体５を流過し、燃焼円筒体５の下方にて折り返して、上向流で燃焼ガス流路１０を流過し、バッフル板１１を経て燃焼ガス排出口１２より排出される。
【００５７】
図６は本発明の第２の実施の形態を説明する構成ブロック図である。ここでは、図１に示す燃料改質器の定常状態での運転に適するように、第１改質添加水流量制御部７０と第２改質添加水流量制御部７２が設けられている。第１改質添加水流量制御部７０は、入力計器として改質器上部２や改質器下部３の各部の温度を測定する熱電対のような温度計Ｔ１〜Ｔ５と、第１改質添加水流路４０を流れる第１改質添加水の流量を測定する第１流量計Ｆ１を有すると共に、流量調整弁６４に対して弁開度信号を送っている。改質器上部２には、混合室４４近傍での第１改質添加水の温度を測定する第１温度計Ｔ１や改質部７の温度を測定する第２温度計Ｔ２が設けられている。改質器下部３には、第１変成部２１の温度を測定する第３温度計Ｔ３、第２変成部２６の温度を測定する第４温度計Ｔ４、並びに選択酸化部３６の温度を測定する第５温度計Ｔ５が設けられている。
【００５８】
第２改質添加水流量制御部７２は、入力計器として第１改質添加水流路４０を流れる第１改質添加水の流量を測定する第１流量計Ｆ１、第２改質添加水流路４５を流れる第２改質添加水の流量を測定する第２流量計Ｆ２、改質原料流路５０を流れる改質原料の流量を測定する第３流量計Ｆ３を有すると共に、流量調整弁６５に対して弁開度信号を送っている。
【００５９】
第１改質添加水流量制御部７０は、改質器上部２や改質器下部３の各部の温度を、第１温度計Ｔ１〜第５温度計Ｔ５により測定し、各部に予め設定された設定温度よりも低下したときは、流量調整弁６４の弁を閉じて第１改質添加水流量を減少させる。すると、例えば第１変成部２１等の各部の温度が昇温して、第１改質添加水流量制御部７０によるフィードバック制御にて設定温度に維持される。第２改質添加水流量制御部７２は、例えば第３流量計Ｆ３の流量信号と改質原料の組成より、改質する改質原料中の炭素量を演算し、次に演算された炭素量に対して一定の比率をもつ改質添加水量を演算する（以下、改質添加水と改質原料中炭素とのモル比率を、「Ｓ／Ｃ」(Steam/Carbon)にて表す）。そして、第２改質添加水流量制御部７２は、演算された改質添加水量から第１流量計Ｆ１にて計測された第１改質添加水の水量を控除して、第２改質添加水として供給すべき水量を演算し、流量調整弁６５に対して弁開度信号を送って、第２流量計Ｆ２で測定する第２改質添加水の流量が演算された供給水量になるように制御する。
【００６０】
本実施の形態によれば、第２改質添加水流量制御部７２を設けているので、改質器の定常運転時において、改質添加水の総流量、即ちＳ／Ｃを変えることなく第１改質添加水と第２改質添加水との流量比率を調整することができる。そこで、第１改質添加水流量制御部７０により各部の温度を安定的に制御することができる。例えば、第１変成部２１の温度分布が何らかの原因で高温側にシフトした場合に、第１改質添加水流量制御部７０と第２改質添加水流量制御部７２を連携させて、第１改質添加水注入流路６６上の流量調整弁６４と第２改質添加水注入流路６７上の流量調整弁６５を操作して第２改質添加水の流量を適宜減らすと同時に、第１改質添加水の流量を増やすことにより、第１変成部２１の温度分布を適正の温度分布に戻すことができる。かくして各運転負荷における最適のＳ/Ｃを常に保持することで改質の熱効率を改善することができる。
【００６１】
次に、本発明による燃料改質器の第３の実施形態を説明する。図７は、第３の実施形態による燃料改質器の縦断面図である。なお、図７において、前記図１と同一又は対応する部材又は要素は、同一の符号を付し、重複する説明を省略する。
【００６２】
図において、内円筒体２９と中円筒体３０は、第２変成部２６の改質器下部３の外壁と同軸に設けられたもので、内円筒体２９が中心側、中円筒体３０が周縁側に設けられている。ガス導入流路３１は、内円筒体２９の中心側に形成される空間であって、内円筒体２９の第１変成部２１側の端部には円環状バッフル板２７の開口部が接続されている。第２変成触媒充填層２５は、内円筒体２９の周縁側と中円筒体３０の中心側の間に形成された空間で、第２変成触媒が充填されている。ガス導出流路３２は、中円筒体３０の周縁側と改質器下部３の外壁、並びに第１変成部２１と第２変成部２６との間隙に設置された円環状バッフル板２７と第２変成部の底面３９によって形成された空間である。ガス導入流路３１と第２変成触媒充填層２５とは、内円筒体２９の第１の開口部としての下端開口部３３によって連通されている。第２変成触媒充填層２５とガス導出流路３２とは、中円筒体３０の第２の開口部としての上端開口部２８によって連通されている。
【００６３】
このように構成された第２変成部２６においては、第１変成部２１を出た改質ガスは下向流でガス導入流路３１を通過して、内円筒体２９の下端開口部３３にて折り返し、上向流で第２変成触媒充填層２５を通過し、そして、第２変成触媒充填層２５を出た改質ガスは中円筒体３０の上端開口部２８にて折り返し、下向流でガス導出流路３２を通過し、選択酸化部３６へ導かれるようになっている。選択酸化部３６には、選択酸化部３６の中心部に改質ガスが通過できない円筒体状中空部３６Ｂが設けてある。円筒体状中空部３６Ｂを設けると、選択酸化部３６の触媒充填量及び温度分布が最適化される。かくして本実施形態にかかる燃料改質器の変成部及び選択酸化部における温度分布を最適化し、改質器の性能をさらに向上させることができる。
なお、本実施形態にかかる燃料改質器の運転方法については、前述した第１実施形態と同じなので、説明を省略する。
【００６４】
次に、本発明による燃料改質器の第４の実施形態を説明する。図８は、第４の実施形態による燃料改質器の縦断面図である。なお、図８において、前記図１と同一又は対応する部材又は要素は、同一の符号を付し、重複する説明を省略する。図において、中低温ユニット３には、筒状に第１の変成触媒を充填した第１変成部２１と、環状に第２の変成触媒を充填した第２変成部２６Ａと、第２変成部２６Ａの外周に沿って同軸円筒状に位置する選択酸化部３６Ａが設けられている。
【００６５】
第２変成部２６Ａには、中低温ユニット３の外壁と同軸に設けられた内円筒体２９Ａと、中低温ユニット３の外壁と同軸であって、内円筒体２９Ａの外周側に設けられた中円筒体３０Ａとが設けられている。第２変成部２６Ａの触媒充填層２５Ａは、第２変成触媒が収容される円環状の空間で、内円筒体２９Ａの外周面と中円筒体３０Ａの内周面によって形成されている。円環状バッフル板２７Ａは、第１変成部２１と第２変成部２６Ａとの間隙に設置されるもので、円環の中心部にガス分散板３４Ａが設けられている。
【００６６】
ガス導入流路３１Ａは、円環状バッフル板２７Ａ、選択酸化部３６Ａの内側に位置する中円筒体３０Ａの第１変成部２１側の内周面、並びに内円筒体２９の第１変成部２１側の外周面によって形成された空間で、第１変成部２１を通過した改質ガスを第２変成部２６Ａに導入する流路である。ガス導出流路３２Ａは、中円筒体３０Ａの底面４３側の内周面、第２変成部２６Ａの底面３９、内円筒体２９Ａの内周面、並びに選択酸化部３６Ａの第１変成部２１対向部とを連絡する管路７０Ａによって形成された空間で、第２変成部２６Ａを通過した改質ガスを選択酸化部３６Ａに導入する流路である。管路７０Ａは、内円筒体２９Ａの一端と接続され、中円筒体３０Ａを貫通する円形断面や矩形断面の筒体で、ガス導入流路３１Ａの流れを阻害しない程度の管径となっている。管路７０Ａは、ガス導入流路７１Ａ側に設けられた第２の開口部２８Ａを有している。第１の開口部３３Ａは、中円筒体３０Ａの底面３９側に位置する内円筒体２９の一端に設けられている。選択酸化用空気の導入口５８は、第１の開口部３３Ａの近傍に配置されており、好ましくは第１の開口部３３Ａの内側に若干挿入された態様で配置されているとよい。選択酸化用空気の導入口５８が第１の開口部３３Ａの近傍に設置されているので、第２変成部２６Ａにて変成された改質ガスと選択酸化用空気とが適切に混合されて、選択酸化部３６Ａでの選択酸化反応が効果的に進行する。
【００６７】
選択酸化部３６Ａは、中低温ユニット３の内周面と中円筒体３０Ａの外周面によって形成された選択酸化触媒充填層３５Ａを有しており、更にガス導入流路７１Ａとガス導出流路７２Ａが設けられている。ガス導入流路７１Ａは、中低温ユニット３の内周面、中円筒体３０の外周面、円環状バッフル板２７Ａによって形成される空間で、第２変成部２６Ａを通過した改質ガスを選択酸化触媒充填層３５Ａに導く。ガス分散板３７Ａは、ガスの流れを均質化するもので、ガス導入流路７１Ａに設けられている。ガス導出流路７２Ａは、中低温ユニット３の内周面、中円筒体３０Ａの外周面、第２変成部２６Ａの底面３９、中低温ユニット３の底面４３、並びに改質ガス導出管５５の内周面によって形成される空間で、選択酸化触媒充填層３５Ａを通過した改質ガスを改質ガス導出管５５に導く構成となっている。
【００６８】
このように構成された第２変成部２６Ａにおいては、第１変成部２１を通過した改質ガスは、下向流でガス導入流路３１Ａとガス分散板３４Ａを通過し、次に触媒充填層２５Ａを通過する。そして、第２変成触媒充填層２５Ａを通過した改質ガスは、第１の開口部３３Ａで折り返して、上向流でガス導出流路３２Ａを通過し、第２の開口部２８Ａを通過して、ガス導入流路７１Ａを経由して選択酸化部３６Ａへ導かれる。即ち、第２変成部２６Ａを通過した改質ガスは、ガス導入流路７１Ａとガス分散板３７Ａを通過し、次に選択酸化触媒充填層３５Ａを下向流で通過し、さらにガス導出流路７２Ａを通過して系外へ導かれる。
【００６９】
このように第２変成部２６Ａと選択酸化部３６Ａを同心円状に構成すると、改質ガスの流れる量が多くなりがちな中心部に第２変成部２６Ａが位置しているので、第２変成部２６Ａの外周縁部に位置する選択酸化部３６Ａに対して改質ガスが均一に流れ、選択酸化反応が均一に進行する。そこで、選択酸化部３６Ａに充填される選択酸化触媒の量が最適化されると共に、温度分布も最適化される。
【００７０】
なお、上記第１乃至第４実施の形態においては、高温ユニットとしての改質器上部２が上側に配置され、中低温ユニットとしての改質器下部３が下側に配置される燃料改質器を説明したが、本発明はこれに限定されるものではなく、燃料改質器を上下反転させて用いることもできる。
【００７１】
また、上記第１乃至第４実施の形態においては、改質器上部２と改質器下部３との連結部間隙に円環状バッフル板１８を設け、改質器上部２の底面、改質器下部３の上面、並びに連結流通管１９によって改質ガスと改質添加水との熱交換部２４を形成する場合を示しているが、本発明はこれに限定されるものではなく、要するに第１改質添加水を蒸発し過熱すると共に、各部の最適温度分布を達成することができればよい。
【００７２】
例えば、第１変成部２１の底面と第２変成部２６の上面とを連結流通管によって連結し、該連結部の間隙に円環状バッフル板を設ける構成とし、第１変成部２１の底面、第２変成部２６の上面、並びに連結流通管によって改質ガスと第１改質添加水との熱交換を行う第２の熱交換部を設けてもよい。さらに、第２変成部２６の底面と選択酸化部３６の上面とを連結流通管によって連結し、該連結部の間隙に円環状バッフル板を設ける構成とし、第２変成部２６の底面、選択酸化部３６の上面、並びに連結流通管によって改質ガスと第１改質添加水との熱交換を行う第３の熱交換部を設けることもできる。また、第３熱交換部を設ける場合には、第２変成部２６の底面と選択酸化部３６の上面とを連結した連結流通管の内側に、選択酸化用空気の導入口を設置することもできる。
【００７３】
【発明の効果】
本発明の燃料改質器によれば、燃料が燃焼する燃焼室と、該燃焼室の外周面側に設けられると共に、環状に改質触媒を充填した改質部を有する高温ユニットと、前記高温ユニットと連結される側に設けられると共に、筒状又は環状に変成触媒を充填した変成部と、前記高温ユニットと連結される側とは反対側に設けられると共に、筒状又は環状に選択酸化触媒を充填した選択酸化部を有する中低温ユニットを有する構造としているので、高温と低温の二つのユニットに大きく２分割されて組成されており、一体型の燃料改質器の構造を簡単化し、製造コストの低下と熱効率の向上を図ることができる。
また、本発明の燃料改質器によれば、高温ユニットの改質部を通過した改質ガスを、中低温ユニットの変成部側に供給する連結流通管と、当該連結流通管によって連結される前記高温ユニットと前記中低温ユニットを一体に収容する容器とを備えているので、熱応力の発生を著しく軽減し、燃料改質器の耐久性を向上させることができる。
【００７４】
また、本発明の燃料改質器によれば、さらに高温ユニット及び中低温ユニットの外壁と容器の内壁との間隙に形成された改質添加水流路と、高温ユニットに改質原料を供給する改質原料供給路と、改質添加水流路と改質原料供給路を互いに連通する混合室を設ける構成とすると、改質添加水流路と高温ユニット及び中低温ユニットとの熱交換によって改質添加水を改質ガスの顕熱で蒸発、過熱し、発生した改質添加水の高温過熱蒸気を用いて混合室にて気体燃料の場合燃料を予熱し、液体燃料の場合燃料を気化することができる。かくして本発明の燃料改質器を都市ガス、ＬＰＧや嫌気性消化ガス等の気体燃料にも、灯油やナフサ等の液体燃料にも適用することができる。
【００７５】
また、本発明の燃料改質器によれば、さらに高温ユニットに改質原料を供給する改質原料供給路と、中低温ユニットを経由せず、前記高温ユニットに直接改質添加水を供給する第２改質添加水流路と、改質添加水流路、前記改質原料供給路並びに前記第２改質添加水流路を互いに連通する混合室を設ける構成とすると、起動時間を大幅に短縮すると共に各反応部の温度制御を容易にすることができる。
【００７６】
また、本発明の燃料改質器によれば、前記中低温ユニットは、前記高温ユニット側に設けられると共に、筒状又は環状に第１の変成触媒を充填した第１変成部と、筒状又は環状に第２の変成触媒を充填した第２変成部とを有する変成部を備え、前記第２変成部が前記選択酸化部に対して同軸円筒状に位置する構成とすると、第２変成部と選択酸化部が同心円状に配置されて改質器全体がコンパクトになる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態の基本構成を示す縦断面図である。
【図２】図１の装置における起動時の運転手順を説明する流れ図である。
【図３】図１の装置における起動時の予熱状態を説明する縦断面図である。
【図４】図１の装置における改質原料の供給開始状態を説明する縦断面図である。
【図５】図１の装置における第１改質添加水の供給開始状態を説明する縦断面図である。
【図６】本発明の第２の実施の形態を説明する構成ブロック図である。
【図７】本発明の第３の実施の形態を示す縦断面図である。
【図８】本発明の第４の実施の形態を示す縦断面図である。
【符号の説明】
１改質器
２改質器上部（高温ユニット）
３改質器下部（中低温ユニット）
４バーナー
５燃焼円筒体
６改質触媒充填層
７改質部
８改質部入口ガス流路
１０燃焼ガス流路
１３容器
１４断熱材
１５隔壁
１６改質ガス流路
１７改質器上部底面
１８バッフル板
１９コルゲート形伸縮管（連結流通管）
２０第１変成触媒充填層
２１第１変成部
２４熱交換部
２５、２５Ａ第２変成触媒充填層
２６、２６Ａ第２変成部
２８、２８Ａ中円筒体上端開口部（第２の開口部）
２９、２９Ａ内円筒体
３０、３０Ａ中円筒体
３１、３１Ａガス導入流路
３２、３２Ａガス導出流路
３３、３３Ａ内円筒体下端開口部（第１の開口部）
３５、３５Ａ選択酸化触媒充填層
３６、３６Ａ選択酸化部
４０第１改質添加水流路（改質添加水流路）
４４混合室
４５第２改質添加水流路
５０燃料流路（改質原料供給路）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel reformer that reforms a hydrocarbon-based fuel to produce a reformed gas rich in hydrogen, and more particularly to an integrated fuel reformer that has a relatively simple structure and is inexpensive to manufacture. Further, the present invention is a solid polymer type capable of dealing with various hydrocarbon fuels such as gas fuels such as city gas, LPG and anaerobic digestion gas, and liquid fuels such as kerosene and gasoline as hydrocarbon fuels. The present invention relates to an integrated fuel reformer that produces reformed gas suitable for a fuel cell.
[0002]
[Prior art]
In recent years, fuel cell cogeneration systems that can supply both heat and electricity have been developed against the background of global environmental conservation. In this system, a hydrocarbon-based fuel such as natural gas is steam reformed by a reformer to produce a reformed gas rich in hydrogen, and the produced reformed gas is supplied to a fuel cell to generate power. . Therefore, the reformer is an important development factor for the economy and energy efficiency of the entire system.
[0003]
In general, when the fuel cell is a phosphoric acid fuel cell, the reformer includes a combustion unit that supplies reforming heat, a reforming unit that reforms hydrocarbon into hydrogen and CO by a reforming reaction with steam, In addition, there is provided a shift section that converts CO in the reformed gas into hydrogen and CO2 by a shift reaction with steam. When the fuel cell is a polymer electrolyte fuel cell, the reformer selects the combustion unit that supplies reforming heat, the reforming unit, the shift unit, and the residual CO in the CO shift gas as oxygen. And a selective oxidation part that is removed by a selective oxidation reaction. In order to reduce the size of the reformer and improve the thermal efficiency, an integrated reformer in which each component of the reformer is integrated has been proposed. For example, a multi-cylinder reformer or a laminated plate reformer is proposed. Etc. are disclosed.
[0004]
[Problems to be solved by the invention]
However, in the conventional multi-cylindrical reformer, a high-temperature burner combustion section, a reforming section that performs a high-temperature endothermic reaction that requires heating, a shift reaction section that performs a medium-to-low-temperature heat release reaction that requires cooling, and a selective oxidation section Are arranged in a coaxial multi-cylindrical body, there is a problem that the structure is considerably complicated and the manufacturing cost is high. Further, in the conventional multi-cylindrical reformer, the length and area of the cylindrical partition wall that divides each part is large and the temperature difference between the parts is large, so that the thermal stress generated at the connecting part of each part is large, and The heat flow that passes through the partition is large. Therefore, there are problems such as temperature distribution of each part affecting each other, temperature control is difficult, and startup time is long. The conventional laminated flat plate reformer also has basically the same problems as the multi-cylinder reformer.
[0005]
Further, the conventional reformer deals with either gaseous fuel such as city gas or natural gas and liquid fuel such as gasoline, kerosene, or methanol. That is, a gaseous fuel preheating and a mixing mechanism with water vapor are required for the gaseous fuel. On the other hand, liquid fuel requires a liquid fuel vaporization mechanism. Therefore, in the conventional reformer, gas fuel and liquid fuel are prepared separately to meet customer demand.
[0006]
However, gas fuels and liquid fuels are supplied by different suppliers and are handled differently for taxation such as volatile oil tax. Therefore, if the reformer can cope with both gaseous fuel and liquid fuel, there is an advantage that the fuel cell user can use the optimum fuel according to the change in the economic environment. In addition, in the case of manufacturing a reformer that can be applied to both gaseous fuel and liquid fuel, compared with the case of separately manufacturing the reformer for gaseous fuel and liquid fuel, the reformer is improved by mass production effect. There is also a possibility that the manufacturing cost of the product will decrease.
[0007]
The present invention solves the above-mentioned problems, and a first object is to provide a fuel reformer having a relatively simple structure and a low manufacturing cost. The second object is to provide a fuel reformer that is less likely to generate thermal stress and has excellent durability. A third object is to provide a fuel reformer that can easily control the optimum temperature distribution of each part of the fuel reformer, has high thermal efficiency, and has a short start-up time. A fourth object is to provide a fuel reformer that can reform both gaseous fuel and liquid fuel.
[0008]
[Means for Solving the Problems]
As shown in FIG. 1, the fuel reformer of the present invention that achieves the first object is provided with a combustion chamber 5A in which fuel is combusted, and an outer peripheral surface side of the combustion chamber 5A. A high-temperature unit 2 having a reforming section 7 filled with, a shift section (21, 26) that is provided on the side connected to the high-temperature unit 2 and is filled with a shift catalyst in a cylindrical or annular shape, A medium / low temperature unit 3 having a selective oxidation unit 36 which is provided on the side opposite to the connected side and is filled with a selective oxidation catalyst in a cylindrical or annular shape, and a reformed gas which has passed through the reforming unit of the high temperature unit 2 The connecting flow pipe 19 to be supplied to the transformation section side of the medium / low temperature unit 3, the high temperature unit 2 connected by the connection flow pipe 19, and the container 13 for housing the medium / low temperature unit 3 integrally are provided.
[0009]
The combustion chamber 5 A typically has a burner 4 inside, and fuel is burned by the burner 4. More typically, the burner 4 is provided on the central axis of the combustion chamber 5A.
In the fuel reformer configured as described above, in the high temperature unit 2, the temperature of the reforming unit 7 is raised from, for example, a state of about room temperature at the time of startup to an operating temperature at the time of steady operation. In the medium / low temperature unit 3, the temperature of the transformation section (21, 26) is raised from the state of room temperature at the time of startup to the temperature of the transformation section at the time of steady operation, and the temperature of the selective oxidation section 36 is about room temperature at the time of startup. The temperature is raised from the state to the selective oxidation part temperature during steady operation. As described above, the high temperature unit 2 and the medium / low temperature unit 3 are divided according to the operating temperature in the steady state, and the reformed gas is circulated along the process flow of reforming → transformation → selective oxidation by the connecting circulation pipe 19. In addition, since the container 13 integrally accommodates the structure, the structure is simple and the manufacturing cost is reduced. Preferably, the high temperature unit 2 and the medium / low temperature unit 3 have the same axis, and the cross-sectional shape is circular or rectangular (including a square), a fuel reformer having a shape that matches the installation location of the customer is provided. In particular, the circular flow provides a uniform gas flow and requires less material for manufacturing. If it is a rectangle, especially a square, installation becomes easy.
[0010]
Preferably, in the fuel reformer of the present invention, a reformed / added water channel 40 formed in a gap between the outer wall of the high temperature unit 2 and the medium / low temperature unit 3 and the inner wall of the container 13, and the reformed / added water channel It is good to set it as the structure provided with the reforming addition water inlet 41 provided in the opposite side to the side connected with the high temperature unit 2 of the 40 medium / low temperature unit 3. If comprised in this way, at the time of a steady operation, heat exchange with the reforming addition water and reformed gas which flow through the reforming addition water flow path 40 will be performed through the outer wall of the high temperature unit 2 and the medium-low temperature unit 3, and thermal efficiency will increase.
[0011]
Preferably, in order to achieve the fourth object, in the fuel reformer of the present invention, the reforming material supply channel 50, the reforming / addition water channel 40 and the reforming water channel 40 for supplying the reforming material to the high temperature unit 2 are further improved. If the raw material supply path 50 is provided with the mixing chamber 44 that communicates with each other, the reformed additive water in the superheated steam state in the reformed additive water flow path 40 is used as the reforming raw material in the mixing chamber 44. On the other hand, processing for smoothly performing the reforming reaction in the reforming unit 7 is performed. That is, when the reforming raw material is a liquid fuel, the fuel is vaporized, and when the reforming raw material is a gaseous fuel, the fuel is preheated.
[0012]
Preferably, in order to achieve the third and fourth objects, in the fuel reformer of the present invention, a reforming material supply path 50 for supplying the reforming material to the high temperature unit 2 and the medium / low temperature unit 3 are further provided. The second reformed / added water channel 45 for directly supplying the reformed / added water to the high-temperature unit 2 without passing through, the reformed / added water channel 40, the reforming raw material supply channel 50 and the second reformed / added water channel 45 are provided. The mixing chamber 44 may be configured to communicate with each other.
[0013]
When the fuel reformer configured as described above is started, reformed additive water as a preheating heat medium is supplied from the second reformed additive water channel 45 and is exchanged with the combustion gas in the mixing chamber 44. Generate steam for reforming addition water. The generated steam is caused to flow back into the reforming / addition water flow path 40, so that the medium / low temperature unit 3 is preheated and preheated without using a heat medium such as nitrogen gas to preheat the medium / low temperature unit 3. Reduce time. In addition, preheating the medium / low temperature unit 3 before introducing the reformed gas prevents water condensation in the shift catalyst layer and the selective oxidation catalyst layer of the medium / low temperature unit 3 when the reformed gas is introduced, thereby improving the catalyst life. Can be made.
Further, during the steady operation of the fuel reformer, without changing the total flow rate of the reformed additive water, the ratio of each water amount in the reformed additive water channel 40 and the second reformed additive water channel 45 is adjusted. The temperature of each part can be controlled stably.
[0014]
The fuel reformer of the present invention that achieves the third object further includes a baffle plate 18 provided in a gap between the high temperature unit 2 and the medium / low temperature unit 3, and the high temperature unit 2 and the medium / low temperature unit 3. When the heat exchange unit 24 is provided on the opposite surface and has a structure including a heat exchange unit 24 that performs heat exchange between the reformed gas sent from the high temperature unit 2 to the medium / low temperature unit 3 and the reformed additive water, In the exchange unit 24, heat exchange between the reformed additive water and the reformed gas flowing through the reformed additive water flow path 40 is performed through the outer walls of the high temperature unit 2 and the medium / low temperature unit 3, and the reformed additive water is evaporated and superheated. At the same time, the temperature distribution inside the fuel reformer becomes appropriate.
[0015]
In the fuel reformer of the present invention that achieves the second and third objects, when the connecting flow pipe 19 has a structure having an elastic member that expands and contracts in the axial direction of the connecting flow pipe 19, the fuel reformer cools at the time of startup. The strain caused by thermal expansion between the high temperature unit 2, the medium / low temperature unit 3, and the container 13 can be absorbed by expansion and contraction of the connecting flow pipe 19 between the heated state and the state in which the temperature is raised as in the steady operation. Even if is repeated, the influence of thermal stress can be reduced. The elastic member includes a member having a corrugated cross section such as a bellows and a member that can be easily bent and deformed such as a diaphragm. Furthermore, since the surface area of the expansion / contraction member is wider than that of the straight pipe, heat exchange between the reformed gas flowing inside the pipe and the reformed additive water flowing outside the pipe can be performed efficiently.
[0016]
In the fuel reformer of the present invention, when the high temperature unit 2 is disposed on the upper side and the medium / low temperature unit 3 is disposed on the lower side of the high temperature unit 2, when the reforming water addition flow path is provided, The phase change from water to water vapor, the difference in specific gravity between water and water vapor, and the direction of gravity become natural. Further, in the fuel reformer of the present invention, when the high temperature unit 2 is disposed on the lower side and the medium / low temperature unit 3 is disposed on the upper side of the high temperature unit 2, for example, water supply to the fuel reformer and reforming raw materials are performed. When existing pipes are used for the supply of fuel, it may be convenient in terms of installation of the fuel reformer by installing it upside down.
[0017]
Preferably, in the fuel reformer of the present invention, the shift section is provided on the high temperature unit 2 side, and the first shift section 21 filled with the first shift catalyst in a cylindrical or annular shape and the selective oxidation section 36 side. And having a second shift section 26 filled with a second shift catalyst in a cylindrical or annular shape, the temperature distribution in the shift section is optimized, and the heat generated by the shift reaction is removed. Becomes easier. In addition, during steady operation, the first shift section 21 is at a higher temperature than the second shift section 26. Therefore, the first shift catalyst is used so that the shift reaction proceeds efficiently at the steady temperature. And the composition of the second shift catalyst can be appropriately selected.
[0018]
Preferably, in the fuel reformer of the present invention, for example, as shown in FIG. 7, the second transformation section 26 further includes an inner cylindrical body 29 provided coaxially with the outer wall of the medium / low temperature unit 3, and the medium / low temperature unit 3. A reformed gas that is coaxial with the outer wall of the inner cylindrical body 29 and is provided on the outer peripheral side of the inner cylindrical body 29, and has passed through the first metamorphic portion 21 by the inner peripheral surface of the inner cylindrical body 29. The introduction flow path 31 is formed, and the catalyst filling layer 25 of the second shift section 26 is formed by the outer peripheral surface of the inner cylindrical body 29 and the inner peripheral surface of the intermediate cylindrical body 30, and the outer peripheral surface of the intermediate cylindrical body 30 and the medium / low temperature unit The gas outlet channel 32 may be formed by the inner peripheral surface 3. That is, the reformed gas that has passed through the first shift unit 21 passes through the gas introduction channel 31, then passes through the catalyst packed bed 25, and further passes through the gas outlet channel 32 and is guided to the selective oxidation unit 36. .
[0019]
Preferably, in the fuel reformer of the present invention, for example, as shown in FIG. 7, the second shift section 26 further communicates the gas introduction flow path 31 and the catalyst packed bed 25 of the second shift section 26, The first opening 33 provided on the selective oxidation part 36 side of the inner cylindrical body 29, the catalyst filling layer 25 of the second shift part 26, and the gas outlet passage 32 communicate with each other, and the first cylindrical part 30 of the middle cylindrical body 30 is connected. It is good to set it as the structure provided with the 2nd opening part 28 provided in the 1st transformation part 21 side. That is, the reformed gas that has passed through the first shift section 21 passes through the gas introduction flow path 31 in a downward flow, is folded back at the first opening 33, and passes through the catalyst packed bed 25 in an upward flow. The reformed gas that has exited the catalyst packed bed 25 is folded back at the second opening 28, passes through the gas outlet passage 32 in a downward flow, and is guided to the selective oxidation unit 36.
[0020]
Preferably, in the fuel reformer of the present invention, for example, as shown in FIGS. 1 and 7, a baffle plate 38 is provided in the gap between the transformation portion (21, 26) and the selective oxidation portion 36. When the selective oxidation air introduction port 58 is arranged inside the central opening, the reformed gas transformed in the transformation section and the selective oxidation air are appropriately mixed, and the selective oxidation reaction in the selective oxidation section 36 is performed. Progresses effectively.
[0021]
Preferably, in the fuel reformer of the present invention, as shown in FIG. 7, for example, the selective oxidation unit 36 is configured so that the reformed gas sent from the shift unit (21, 26) does not pass near the center. If the cylindrical hollow portion 36B is provided, the flow in the vicinity of the central portion where the amount of the reformed gas tends to increase is suppressed, so that the reformed gas is evenly distributed around the peripheral portion of the selective oxidation portion 36. The selective oxidation reaction proceeds uniformly. Therefore, the amount of the selective oxidation catalyst filled in the selective oxidation unit 36 is optimized, and the temperature distribution is also optimized.
[0022]
Preferably, in the fuel reformer of the present invention, for example, as shown in FIG. 8, the medium / low temperature unit 3 is provided on the high temperature unit 2 side, and is filled with the first shift catalyst in a cylindrical shape or an annular shape. A shift section (21, 26A) having a shift section 21 and a second shift section 26A filled with a second shift catalyst in a cylindrical or annular shape is provided, and the second shift section 26A is coaxial with the selective oxidation section 36A. If it is set as the structure located in a cylindrical shape, the 2nd shift part 26A and the selective oxidation part 36A will be arrange | positioned concentrically, and the whole reformer will become compact.
[0023]
Preferably, in the fuel reformer of the present invention, for example, as shown in FIG. 8, the second shift section 26 A includes an inner cylindrical body 29 A provided coaxially with the outer wall of the medium / low temperature unit 3, and the medium / low temperature unit 3. It has an inner cylindrical body 30A that is coaxial with the outer wall and provided on the outer peripheral side of the inner cylindrical body 29A. The catalyst filling layer 25A of the second shift section 26A is provided in a space formed by the outer peripheral surface of the inner cylindrical body 29A and the inner peripheral surface of the middle cylindrical body 30A. The selective oxidation catalyst packed layer 35 A of the selective oxidation unit 36 A is provided in a space formed by the outer peripheral surface of the intermediate cylindrical body 30 A and the inner peripheral surface of the intermediate / low temperature unit 3. The gas introduction flow path 31A is formed in the facing portion between the first shift portion 21 and the second shift portion 26A, and allows the reformed gas that has passed through the first shift portion 21 to flow into the second shift portion 26A. The gas lead-out flow path 32A is formed by a pipeline 70A that connects the bottom surface side of the second shift section 26A and the first shift section 21 facing portion of the selective oxidation section 36A, and the modified gas passage that has passed through the second shift section 26A. The quality gas is sent to the selective oxidation unit 36A.
[0024]
In the apparatus configured as described above, the reformed gas that has passed through the first shift section 21 passes through the gas introduction flow path 31A, then passes through the second shift section 26A, and further passes through the gas outlet flow path 32A. Then, it is guided to the selective oxidation unit 36A. Further, since the selective oxidation unit 36A is located in an annular shape with the second shift unit 26A as a central part, the flow in the vicinity of the reformer central part, which tends to increase the amount of reformed gas, is suppressed, and the selective oxidation part The reformed gas flows uniformly to the peripheral portion of 36A, and the selective oxidation reaction proceeds uniformly. As a result, the amount of the selective oxidation catalyst filled in the selective oxidation unit 36A is optimized, and the temperature distribution is also optimized.
[0025]
Preferably, the fuel reformer of the present invention further includes a baffle plate 27A provided at a facing portion between the first shift portion 21 and the second shift portion 26A, for example, as shown in FIG. The channel 31A may be formed by the baffle plate 27A, the inner circumferential surface of the middle cylindrical body 30A, and the outer circumferential surface of the inner cylindrical body 29A. Preferably, the baffle plate 27A has an annular shape, and when the gas dispersion plate 34A is provided at the center of the ring, the reformed gas uniformly flows through the second shift portion 26A, and the shift reaction proceeds uniformly.
[0026]
Preferably, in the fuel reformer of the present invention, as shown in FIG. 8, for example, the gas outlet flow path 32A includes the bottom surface 39 of the middle cylindrical body 30A, the inner peripheral surface of the inner cylindrical body 29, and the inner cylindrical body 29A. When formed by the pipe line 70A that connects the inner peripheral surface and the selective oxidation unit 36A, the gas outlet flow path 32A is effectively arranged with respect to the compact reformer. Preferably, when the selective oxidation air introduction port 58 is disposed inside the first opening 33A located on the bottom surface 39 side of the middle cylinder 30A of the inner cylinder 29, the metamorphic portion (21, 26A) is provided. The reformed gas thus transformed and the selective oxidation air are appropriately mixed, and the selective oxidation reaction in the selective oxidation unit 36A effectively proceeds.
[0027]
Preferably, in the fuel reformer of the present invention, when the vacuum heat insulating layer 60 is provided on the outer periphery of the container 13, the entire reformer becomes compact and the high temperature unit 2, the medium / low temperature unit 3, and the reformed addition water flow path 40 Since there is little heat loss from the reformed additive water flowing through the reformer, the thermal efficiency of the reformer is improved. Preferably, when the wall surface forming the vacuum heat insulating layer 60 is formed of a highly reflective material such as silver plating or aluminum plating, thermal radiation can be reduced in addition to heat conduction.
[0028]
The fuel reformer of the present invention that achieves the third and fourth objects is provided with a combustion chamber 5A in which fuel burns and an outer peripheral surface side of the combustion chamber 5A as shown in FIG. A high-temperature unit 2 having a reforming section 7 filled with a catalyst, a reforming section (21, 26) for transforming reformed gas that has passed through the reforming section 7 of the high-temperature unit 2, and a reforming section transformed by the transforming section. The medium / low temperature unit 3 having the selective oxidation unit 36 that selectively oxidizes the gas and the reformed additive water are arranged so that heat can be exchanged in the medium / low temperature unit 3, and the reformed additive water is supplied to the high temperature unit 2. The reforming / addition water channel 40 to be supplied, the second reforming / addition water channel 45 for supplying the reforming / addition water directly to the high temperature unit 2 without passing through the medium / low temperature unit 3, and the reforming raw material to be supplied to the high temperature unit 2 Reforming raw material supply channel 50, reforming addition water channel 40, second reforming And a mixing chamber 44 which communicates with each other hydrolytic passage 45 and the reforming material supply conduit 50.
[0029]
When the fuel reformer configured as described above is started, reformed additive water as a preheating heat medium is supplied from the second reformed additive water channel 45 and is exchanged with the combustion gas in the mixing chamber 44. Generate steam for reforming addition water. The generated steam is caused to flow back into the reforming / addition water flow path 40, so that the medium / low temperature unit 3 is preheated and preheated without using a heat medium such as nitrogen gas to preheat the medium / low temperature unit 3. Reduce time. In addition, preheating the medium / low temperature unit 3 before introducing the reformed gas prevents water condensation in the shift catalyst layer and the selective oxidation catalyst layer of the medium / low temperature unit 3 when the reformed gas is introduced, thereby improving the catalyst life. Can be made.
Further, during the steady operation of the fuel reformer, without changing the total flow rate of the reformed additive water, the ratio of each water amount in the reformed additive water channel 40 and the second reformed additive water channel 45 is adjusted. The temperature of each part can be controlled stably.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to cross-sectional views showing a schematic configuration of a reformer according to the present invention.
FIG. 1 is a longitudinal sectional view showing a first embodiment of a fuel reformer according to the present invention. In the figure, the reformer 1 includes a reformer upper part 2 as a high temperature unit and a reformer lower part 3 as a medium / low temperature unit. The reformer upper part 2 has a burner 4 for burning fuel, a combustion cylinder 5 arranged coaxially with the burner 4, and a torus-shaped reforming part 7 containing a reforming catalyst packed layer 6. ing. The burner 4 is provided substantially on the central axis of the combustion cylinder 5. The reforming catalyst used in the reforming catalyst packed layer 6 may be anything as long as it promotes the reforming reaction. For example, a Ni-based reforming catalyst or a Ru-based reforming catalyst is used as the type of catalyst. Examples of the shape of the reforming catalyst include a granular shape, a columnar shape, a honeycomb shape, and a monolith shape. In addition, the illustration regarding the detail of the burner 4 is abbreviate | omitted.
[0031]
The combustion chamber 5 A has a peripheral wall formed by the combustion cylinder 5. A combustion gas flow path 10, a baffle plate 11, and an outlet 12 are provided in the gap between the combustion cylinder 5 and the reforming unit 7. The partition wall 15 separates the combustion gas passage 10 and the reformed gas passage 16 and is formed of a metal material having high heat resistance. The heat insulating material 14 is provided between the combustion chamber 5 A and the partition wall 15, and suppresses heat transfer between the reformed gas exiting the reforming unit 7 and the combustion gas. The baffle plate 11 makes the flow distribution of the combustion gas in the combustion gas flow path 10 uniform, and its structure is annular and has a large number of holes.
[0032]
The reformer lower portion 3 includes a cylindrical first shift portion 21 that houses the first shift catalyst packed bed 20, a cylindrical second shift portion 26 that stores the second shift catalyst packed bed 25, and a selective oxidation catalyst. And a cylindrical selective oxidation unit 36 containing a packed bed 35. Examples of the first shift catalyst used in the first shift catalyst packed bed 20 include an Fe—Cr high temperature shift catalyst and a Pt medium high temperature shift catalyst. Examples of the second shift catalyst used for the second shift catalyst packed bed 25 include a Cu—Zn low temperature shift catalyst and a Pt low temperature shift catalyst. Examples of the shape of the catalyst used for the first shift catalyst packed bed 20 and the second shift catalyst packed bed 25 include a granular shape, a columnar shape, a honeycomb shape, and a monolith shape.
[0033]
The selective oxidation catalyst used for the selective oxidation catalyst packed bed 35 may be anything as long as it has a high selective oxidation property with respect to CO. Examples thereof include a Pt-based selective oxidation catalyst, a Ru-based selective oxidation catalyst, and a Pt-Ru-based selective oxidation catalyst. . Examples of the shape of the catalyst used for the selective oxidation catalyst packed layer 35 include a granular shape, a cylindrical shape, a honeycomb shape, and a monolith shape.
[0034]
The connecting flow pipe 19 connects the bottom surface 17 of the reformer upper part 2 and the upper surface 23 of the reformer lower part 3. For example, a corrugated expansion pipe that expands and contracts in the axial direction of the connection flow pipe 19 is used. Here, the reformer upper part 2 is surrounded by a cylindrical tube, and the bottom surface 17 is provided in a bucket-like bottom plate shape with respect to the reformer upper part 2, and is connected to the central part at the center. An opening leading to the tube 19 is provided. The reformer lower portion 3 is surrounded by a cylindrical tube, and the upper surface 23 is provided in a lid shape with respect to the reformer lower portion 3, and an opening communicating with the connecting flow pipe 19 is provided at the center portion. have. The bottom surface 43 is provided in a bucket-like bottom plate shape with respect to the reformer lower part 3, and has an opening that leads to the reformed gas outlet pipe 55 at the center.
[0035]
When a corrugated expansion / contraction tube is used for the connecting / circulating pipe 19, the bottom surface 17 and the top surface 23 are rigid because the heat expansion / contraction of the reformer upper portion 2 and the reformer lower portion 3 can be absorbed by the deformation of the expansion tube in the axial direction. High material may be used. Moreover, the attachment position with respect to the bottom face 17 and the upper surface 23 of the connection flow pipe 19 is not limited to the center portion, but may be a peripheral edge portion, and a plurality of connection flow pipes 19 may be provided on the bottom face 17 and the upper surface 23. When a straight pipe is used for the pipe portion of the connection flow pipe 19, the connection flow pipe can be absorbed in order to absorb the thermal expansion and contraction of the reformer upper part 2 and the reformer lower part 3 by bending deformation of the bottom surface 17 and the upper surface 23. 19 may be attached to the bottom surface 17 and the upper surface 23 at the center, and the bottom surface 17 and the upper surface 23 may be made of the same material as the other parts of the reformer upper part 2 and the reformer lower part 3. In addition, it is preferable that the bottom surface 17 and the top surface 23 are subjected to corrugation because bending deformation is further facilitated. If it does in this way, the normal pipe which does not have a stretching property can also be used as the connection distribution pipe 19.
[0036]
The container 13 is a cylindrical body that integrally accommodates the reformer upper part 2 and the reformer lower part 3 connected by the connecting flow pipe 19, and the first reformed additive water inlet 41 and the reformed gas outlet pipe are formed on the bottom surface. 55 is provided. The container 13 is provided coaxially with the cylindrical reformer upper part 2 and the reformer lower part 3. The heat insulating layer 60 is provided on the outer periphery of the container 13 and the upper surface of the reformer upper portion 2. As the heat insulating layer to be used, for example, a vacuum heat insulating layer is suitable. The gas dispersion plate 22 is provided in a space formed in the gap between the reforming lower upper surface 23 and the first shift catalyst packed bed 20, and the reformed gas flowing from the connecting flow pipe 19 is uniformly distributed to the first shift catalyst. A perforated plate is used so as to flow into the packed bed 20. The gas dispersion plate 37 is a space formed between the bottom surface of the second shift catalyst filling layer 25 and the selective oxidation catalyst filling layer 35 and is provided below the annular baffle plate 38. A perforated plate is used so that the modified gas flowing from the central opening of 38 flows uniformly into the selective oxidation catalyst packed bed 35.
[0037]
The first reforming addition water flow path 40 is formed in the gap between the outer wall of the reformer upper part 2 and the outer wall of the reformer lower part 3 and the inner wall of the container 13. Since the lower part 3 is a cylinder provided coaxially with the container 13, the section is an annular space. In addition, the first reformed / added water flow path 40 may be formed of a pipe material that penetrates the reformer upper part 2 and the reformer lower part 3 and can exchange heat with a pipe. The first reformed / added water inlet 41 is provided at the lower end of the first reformed / added water flow path 40 on the reformer lower part 3 side. The first reformed / added water injection channel 66 is a pipe that supplies the reformed / added water to the first reformed / added water channel 40 via the flow rate adjusting valve 64 and the first reformed / added water inlet 41. is there. The drain solenoid valve 63 is opened at the time of start-up to allow the reformed additive water or water vapor to flow back through the first reformed additive water channel 40 and is closed during steady operation to close the first reformed additive water channel 40. The reformed additive water supplied to the tank is prevented from leaking outside.
[0038]
The mixing chamber 44 is provided at the upper end of the reformer upper portion 2, and includes a first reforming / adding water channel 40, a second reforming / adding water channel 45, a reforming raw material channel 50, and a reforming unit inlet gas channel. 8 is in communication, and the reformed additive water and the reforming raw material are supplied during the steady operation, and the mixed gas of the reformed additive water and the reforming raw material is sent to the reforming unit 7. The second reformed / added water channel 45 is provided above the mixing chamber 44 so as to communicate with the mixing chamber 44, and has, for example, an annular shape. The second reformed / added water channel 45 is provided with a dispersion plate 46 and an inlet 47, and the reformed / added water is supplied via a flow rate adjusting valve 65 provided in the second reformed / added water inlet channel 67. The The reforming material channel 50 as a reforming material supply channel is an annular channel provided below the second reforming addition water channel 45 and communicating with the mixing chamber 44. The reforming raw material channel 50 is a pipe line in which the dispersion plate 51 and the injection port 52 are provided.
[0039]
The annular baffle plate 18 is provided in the gap between the reformer upper bottom surface 17 and the reforming lower upper surface 23. The baffle plate 18 obstructs the flow of the first reformed / added water flow path 40 and guides the flow of the reformed / added water to the connecting flow pipe 19 side. Heat exchange with the lower material upper surface 23 is made efficient. The heat exchange unit 24 is an annular space formed by the reformer upper bottom surface 17, the reforming lower top surface 23, the baffle plate 18, and the connecting flow pipe 19, and the heat of the reformed gas and the first reformed added water. Exchange is performed.
[0040]
The reformed gas outlet pipe 55 and the selective oxidation air introduction pipe 57 are provided in a double tube shape on the bottom surface 43 of the reformer lower part 3. The selective oxidation air introduction port 58 is an opening provided on the gap side between the second shift catalyst filling layer 25 and the selective oxidation catalyst filling layer 35 of the selective oxidation air introduction pipe 57 and is the center of the annular baffle plate 38. Installed inside the opening. The electromagnetic valve 62 is provided at the reformed gas outlet of the reformed gas outlet pipe 55, and is closed during startup and opened during steady operation.
[0041]
Next, the operation method of the fuel reformer of the present invention will be described. FIG. 2 is a flowchart for explaining an operation procedure at the time of start-up in the apparatus of FIG. 3 is a preheating state at the time of start-up in the apparatus of FIG. 1, FIG. 4 is a supply starting state of the reforming raw material, and FIG. 3 to 5, when the valves 62, 63, 64, 65 are closed, they are painted black, and when the valves 62, 63, 64, 65 are opened, they are outlined.
[0042]
First, an operation method at the time of start-up will be described. Combustion air is sent to the burner 4, the burner 4, the combustion cylinder 5 and the combustion gas flow path 10 are pre-purged, the ignition device is operated, and at the same time, supply of burner fuel is started. Ignition is performed (S100). When the burner ignition is confirmed, the second reformed additive water as the heating medium at the start is injected from the second reformed additive water inlet 47 (see FIG. 3). After ignition, the high-temperature combustion gas turns back at the bottom of the combustion cylinder 5 and preheats the reforming catalyst packed bed 6 while passing through the combustion gas flow path 10, and the second reformed addition water flow path 45 and the mixing chamber 44 are The second reformed additive water as a starting heat medium flowing through is evaporated and superheated. Since the electromagnetic valve 62 at the reformed gas outlet is closed and the drain electromagnetic valve 63 of the first reformed addition water flow path is opened at the time of startup, the generated superheated steam flows back through the first reformed addition water flow path 40, The reformer lower part 3 is preheated (S102). By preheating the reformer lower part 3 above the dew point of the introduced reformed gas before introducing the reformed gas in this way, water condensation in the catalyst layer at the time of reformed gas introduction is prevented, thereby improving the catalyst life. Can do. Then, it is determined whether the inlet temperature of the reforming catalyst packed bed 6 has reached a predetermined temperature (S104), and preheating of the reformer lower part 3 is continued until the predetermined temperature is reached. The predetermined temperature relative to the inlet temperature of the reforming catalyst packed bed 6 varies depending on the type of fuel to be reformed, but is preferably in the range of 450 to 550 ° C, for example.
[0043]
When the inlet temperature of the reforming catalyst packed bed 6 reaches a predetermined temperature, the reformed gas outlet electromagnetic valve 62 is opened and the drain electromagnetic valve 63 of the first reformed / added water channel is switched to closed (S106). Then, the fuel and the selective oxidation air that are about 30 to 50% of the reforming material at the rated load are supplied from the fuel inlet 52 and the selective oxidation air introduction port 58, respectively, and the reforming of the fuel is started (S108). ; See FIG.
[0044]
When the reforming of the fuel starts, the shift reaction and the selective oxidation reaction are exothermic reactions as will be described later, so that the first shift catalyst packed bed 20, the second shift catalyst packed bed 25, and the selective oxidation catalyst packed bed 35 react by themselves. The temperature rises due to heat generation. Then, the temperature of the catalyst layer that becomes the rate limiting for shifting to the steady operation, for example, in the apparatus of FIG. 1, the inlet temperature of the second shift catalyst packed bed 25 as the catalyst layer that takes the longest time to raise the temperature becomes a predetermined temperature. It is determined whether it has been reached (S110). The reforming of fuel by the second reforming addition water is continued until the inlet temperature of the second shift catalyst packed bed 25 reaches a predetermined temperature. The predetermined temperature with respect to the inlet temperature of the second shift catalyst packed bed 25 is preferably in the range of 180 to 220 ° C. when, for example, a Cu—Zn low temperature shift catalyst is used as the second shift catalyst.
[0045]
When the inlet temperature of the second modified catalyst packed bed 25 reaches a predetermined temperature, injection of the first reformed additive water is started from the first reformed additive water inlet 41 (S112), and the fuel and the selective oxidation air are supplied. The introduction amount is gradually increased to the rated flow rate, the start state is terminated, and the steady state is entered (see FIG. 5). Further, the reformed gas discharged from the outlet of the reformed gas outlet pipe 55 can be guided to the burner 4 and used as the burner fuel. By providing a step of preheating each catalyst packed bed of the fuel reformer as an operation at the start of the fuel reformer of the present invention, the start-up time can be shortened and the startability can be improved. Further, according to the present invention, the reforming water is used as a heat medium for preheating the reformer, and it is not necessary to use a heat medium such as nitrogen as in the conventional product. In this case, it is easy to secure the heat medium.
[0046]
Next, the operation state at the time of steady operation of the fuel reformer in the present embodiment will be described. Here, the conditions under which the first reforming additive water, the second reforming additive water, and the reforming raw material are processed in each part of the reformer upper part 2 and the reformer lower part 3 are shown in FIG. And with reference to FIG. The first reformed additive water injected from the first reformed additive water inlet 41 flows through the first reformed additive water channel 40 in a counter flow with the reformed gas flowing inside the reformer lower part 3. The first modified additive water flowing through the first modified additive water flow path 40 evaporates at the same time as the selective oxidation unit 36, the second modification unit 26, and the first modification unit 21 are cooled, and the heat exchange unit 24 reforms the modification unit. 7 is superheated by the high-temperature reformed gas that has exited 7, and led to the mixing chamber 44. The reforming raw material injected from the fuel inlet 52 is vaporized by the superheated steam of the first reforming additive water in the mixing chamber 44 in the case of liquid fuel such as kerosene, and is preheated in the case of gaseous fuel such as city gas. The Here, the temperature of the first reformed addition water superheated steam entering the mixing chamber 44 can be in the range of 400 to 600 ° C., for example, so that the superheated steam has a sufficiently high capacity as a heat source for fuel vaporization or preheating. Have.
[0047]
On the other hand, the second reformed additive water injected from the second reformed additive water inlet 47 evaporates by being heated by the combustion gas while flowing through the second reformed additive water passage 45. The gas is mixed with the mixed gas of the second reformed additive water and the reforming raw material, and guided to the reforming catalyst packed bed 6 through the reforming unit inlet gas flow path 8.
The steam reforming reaction of the fuel is mainly performed in the reforming catalyst packed bed 6. For example, when the reforming raw material is methane, a steam reforming reaction according to the following formula is performed.
CH ₄ + H ₂ O → CO + 3H ₂ ... (1)
[0048]
Since the steam reforming reaction of hydrocarbon is an endothermic reaction, the higher the reaction temperature, the higher the reforming rate of the hydrocarbon and the faster the reaction rate. However, if the temperature is too high, the requirements for the heat resistance specification of the reformer material become severe, and the thermal efficiency tends to decrease due to an increase in the heat dissipated in the reformer. Therefore, the temperature distribution of the reforming catalyst packed bed 6 is set to, for example, 550 to 800 ° C. in the gas flow direction, and the optimum temperature distribution can be further limited depending on the type of the reforming raw material. Further, the reforming rate increases as the amount of water vapor added for the reaction increases, but the heat efficiency decreases due to the increase in the amount of heat for generating water vapor, so the S / C is in the range of 2.2 to 3.5, for example. Is preferred. The reforming reaction heat supply to the reforming catalyst packed bed 6 is performed by using the heat of combustion of the burner fuel in the combustion chamber 5A as a heat source and flowing through the combustion cylinder 5 and the combustion gas passage 10. Heat transfer from the combustion gas.
[0049]
After the temperature of the reformed gas exiting the reforming unit 7 is reduced by the heat exchanging unit 24, the reformed gas is led to the first shift unit 21 and the second shift unit 26, and the shift reaction of the following formula is performed.
CO + H ₂ O → CO ₂ + H ₂ ... (2)
Since this modification reaction is exothermic, lowering the reaction temperature has an advantage that the CO concentration of the reformed gas after modification is lowered, and a disadvantage is that the reaction rate is lowered.
[0050]
Therefore, in the present embodiment, the first shift section 21 having a relatively high reaction temperature and the second shift section 26 having a low reaction temperature are provided, and the reaction speed is increased in the first shift section 21. By reducing the CO concentration of the reformed gas, the efficiency of the total transformation reaction is increased. The temperature distribution of the first shift catalyst packed bed 20 is, for example, 500 to 280 ° C., preferably 450 to 300 ° C. in the gas flow direction, and the temperature distribution of the second shift catalyst packed bed 25 is, for example, in the gas flow direction. 280 to 170 ° C, preferably 250 to 190 ° C. The CO concentration of the reformed gas in each part is about 10% at the inlet of the first shift catalyst packed bed 20, about 3 to 5% at the inlet of the second shift catalyst packed bed 25, and 0 at the outlet of the second shift catalyst packed bed 25. About 3 to 1%. In this way, the temperature distribution of each shift catalyst packed bed is optimized to reduce the residual CO concentration in the reformed gas after shift, and at the same time, the total amount of shift catalyst is reduced, making the reformer more compact and lower cost. Can be achieved.
[0051]
The reformed gas exiting the second shift unit 26 is guided to the selective oxidation unit 36, and the following selective CO oxidation reaction is performed with the selective oxidation air introduced from the selective oxidation air introduction port 58.
CO + (1/2) O ₂ → CO ₂ ... (3)
Oxygen in the air for selective oxidation not only oxidizes and removes CO in the reformed gas by reaction formula (3), but also oxidizes and consumes hydrogen in the reformed gas. In order to increase efficiency, that is, thermal efficiency, it is important to suppress the oxidation reaction between oxygen and hydrogen.
[0052]
In the present embodiment, an annular baffle plate 38 is provided in the gap between the second shift unit 26 and the selective oxidation unit 36, and the selective oxidation air introduction port 58 is disposed in the central opening of the baffle plate 38, thereby reforming gas. And air for selective oxidation are uniformly mixed. Moreover, the temperature distribution of the selective oxidation catalyst packed bed 35 is, for example, 200 to 100 ° C., preferably 150 to 110 ° C. in the gas flow direction. The amount of selective oxidation air introduced may be determined so that the residual CO concentration in the reformed gas after selective oxidation is, for example, 100 ppm or less, preferably 10 ppm or less. In order to increase the hydrogen production efficiency of the reformer, the molar ratio of oxygen in the selective oxidation air and CO in the reformed gas introduced into the selective oxidation unit 36 (O ₂ / CO) is, for example, preferably in the range of 1.2 to 3.0, more preferably in the range of 1.2 to 1.8.
[0053]
Thus, by optimizing the temperature distribution of the selective oxidation catalyst packed bed 35 and improving the mixing of the reformed gas and the selective oxidation air, the CO residual concentration of the reformed gas after selective oxidation is reduced. In addition, the heat efficiency of the reformer can be improved by suppressing the consumption of hydrogen.
[0054]
In the first embodiment, the selective oxidation unit 36 has one stage as described above. However, the selective oxidation unit 36 has two stages, for example, a second selective oxidation unit below the selective oxidation unit 36 shown in FIG. May be provided, and a second selective oxidizer may be provided downstream of the reformer 7.
[0055]
Further, the reformed gas after selective oxidation exiting the selective oxidation unit 36 is obtained from the outlet of the reformed gas outlet pipe 55, but the reformed gas obtained can be supplied to the fuel cell to generate power (of the fuel cell). The detailed illustration is omitted). Generally, in the case of fuel cell power generation using a hydrocarbon reformed gas as fuel, 70 to 80% of the hydrogen in the reformed gas is consumed, and the remaining hydrogen is discharged as an anode offgas. According to the first embodiment, the anode off gas of the fuel cell can be used as the burner fuel.
[0056]
In the above-described embodiment, the burner 4 is configured to use an anode off-gas exclusive combustion method in which the burner fuel during steady operation is provided only by the anode off-gas, or a mixed combustion method in which a reforming material is supplied as an auxiliary fuel together with the anode off-gas. It is good. Combustion gas generated by the combustion by the burner 4 flows down the combustion cylinder 5 in a downward flow, turns back below the combustion cylinder 5 and flows through the combustion gas flow path 10 in an upward flow, and a baffle plate. 11 and is discharged from the combustion gas discharge port 12.
[0057]
FIG. 6 is a block diagram illustrating the configuration of the second embodiment of the present invention. Here, a first reformed / added water flow rate control unit 70 and a second reformed / added water flow rate control unit 72 are provided so as to be suitable for the steady state operation of the fuel reformer shown in FIG. The first reforming addition water flow rate control unit 70 includes thermometers T1 to T5 such as thermocouples for measuring temperatures of the reformer upper part 2 and the reformer lower part 3 as input meters, and the first reforming addition While having the 1st flowmeter F1 which measures the flow volume of the 1st reforming addition water which flows through the water flow path 40, the valve opening degree signal is sent with respect to the flow volume adjustment valve 64. FIG. The reformer upper part 2 is provided with a first thermometer T1 for measuring the temperature of the first reformed additive water in the vicinity of the mixing chamber 44 and a second thermometer T2 for measuring the temperature of the reforming unit 7. . In the reformer lower part 3, a third thermometer T3 for measuring the temperature of the first shift unit 21, a fourth thermometer T4 for measuring the temperature of the second shift unit 26, and the temperature of the selective oxidation unit 36 are measured. A fifth thermometer T5 is provided.
[0058]
The second reformed / added water flow rate control unit 72 has a first flow meter F1 and a second reformed / added water channel 45 that measure the flow rate of the first reformed / added water flowing through the first reformed / added water channel 40 as input meters. A second flow meter F2 for measuring the flow rate of the second reformed additive water flowing through the second flow meter, and a third flow meter F3 for measuring the flow rate of the reformed raw material flowing through the reformed material flow channel 50. The valve opening signal is sent.
[0059]
The first reforming added water flow rate control unit 70 measures the temperature of each part of the reformer upper part 2 and the reformer lower part 3 with the first thermometer T1 to the fifth thermometer T5, and is preset in each part. When the temperature falls below the set temperature, the flow rate adjustment valve 64 is closed to reduce the first reforming addition water flow rate. Then, for example, the temperature of each part such as the first shift part 21 is raised and maintained at the set temperature by the feedback control by the first reformed / added water flow rate control part 70. The second reformed added water flow rate control unit 72 calculates the amount of carbon in the reforming material to be reformed, for example, from the flow rate signal of the third flow meter F3 and the composition of the reforming material, and then the calculated amount of carbon The amount of reformed added water having a certain ratio is calculated (hereinafter, the molar ratio between the reformed added water and the carbon in the reformed raw material is represented by “S / C” (Steam / Carbon)). Then, the second reforming addition water flow rate control unit 72 subtracts the amount of the first reforming addition water measured by the first flow meter F1 from the calculated reforming addition water amount to obtain the second reforming addition water flow. The amount of water to be supplied as water is calculated, and a valve opening signal is sent to the flow rate adjusting valve 65 so that the flow rate of the second reformed additive water measured by the second flow meter F2 becomes the calculated supply water amount. To control.
[0060]
According to the present embodiment, since the second reformed / added water flow rate control unit 72 is provided, the total reformed / added water flow rate, that is, the S / C is not changed during steady operation of the reformer. The flow rate ratio between the first modified additive water and the second modified additive water can be adjusted. Therefore, the temperature of each part can be stably controlled by the first reformed / added water flow rate controller 70. For example, when the temperature distribution of the first transformation unit 21 is shifted to a high temperature side for some reason, the first reforming / adding water flow rate control unit 70 and the second reforming / adding water flow rate control unit 72 are linked to each other. The flow rate adjusting valve 64 on the reforming / addition water injection flow channel 66 and the flow rate adjustment valve 65 on the second reforming / addition water injection channel 67 are operated to reduce the flow rate of the second reforming addition water as appropriate. By increasing the flow rate of the 1 reforming added water, the temperature distribution of the first shift section 21 can be returned to an appropriate temperature distribution. Thus, it is possible to improve the thermal efficiency of reforming by always maintaining the optimum S / C in each operating load.
[0061]
Next, a third embodiment of the fuel reformer according to the present invention will be described. FIG. 7 is a longitudinal sectional view of a fuel reformer according to the third embodiment. In FIG. 7, the same or corresponding members or elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.
[0062]
In the figure, an inner cylindrical body 29 and an intermediate cylindrical body 30 are provided coaxially with the outer wall of the reformer lower part 3 of the second transformation section 26, with the inner cylindrical body 29 being the center side and the intermediate cylindrical body 30 being the circumferential side. It is provided on the edge side. The gas introduction flow path 31 is a space formed on the center side of the inner cylindrical body 29, and an opening portion of the annular baffle plate 27 is connected to an end portion of the inner cylindrical body 29 on the first transformation portion 21 side. ing. The second shift catalyst packed bed 25 is a space formed between the peripheral side of the inner cylinder 29 and the center side of the middle cylinder 30 and is filled with the second shift catalyst. The gas outlet flow path 32 includes an annular baffle plate 27 and a second baffle plate 27 installed in the peripheral side of the middle cylindrical body 30 and the outer wall of the reformer lower part 3, and the gap between the first shift portion 21 and the second shift portion 26. This is a space formed by the bottom surface 39 of the metamorphic part. The gas introduction flow path 31 and the second shift catalyst packed bed 25 are communicated with each other by a lower end opening 33 serving as a first opening of the inner cylindrical body 29. The second shift catalyst packed bed 25 and the gas outlet passage 32 are communicated with each other by an upper end opening 28 serving as a second opening of the middle cylindrical body 30.
[0063]
In the second shift section 26 configured in this way, the reformed gas that has exited the first shift section 21 passes through the gas introduction flow path 31 in a downward flow and enters the lower end opening 33 of the inner cylindrical body 29. The reformed gas that has passed through the second shift catalyst packed bed 25 in an upward flow and then exited the second shift catalyst packed bed 25 is turned back at the upper end opening 28 of the middle cylindrical body 30 and flows downward. Then, the gas passes through the gas outlet channel 32 and is guided to the selective oxidation unit 36. The selective oxidation unit 36 is provided with a cylindrical hollow portion 36B through which the reformed gas cannot pass at the center of the selective oxidation unit 36. When the cylindrical hollow part 36B is provided, the catalyst filling amount and the temperature distribution of the selective oxidation part 36 are optimized. Thus, the temperature distribution in the shift part and the selective oxidation part of the fuel reformer according to the present embodiment can be optimized, and the performance of the reformer can be further improved.
Note that the operation method of the fuel reformer according to the present embodiment is the same as that of the first embodiment described above, and a description thereof will be omitted.
[0064]
Next, a fuel reformer according to a fourth embodiment of the present invention will be described. FIG. 8 is a longitudinal sectional view of a fuel reformer according to the fourth embodiment. In FIG. 8, members or elements that are the same as or correspond to those in FIG. 1 are given the same reference numerals, and redundant descriptions are omitted. In the figure, the medium / low temperature unit 3 includes a first shift portion 21 filled with a first shift catalyst in a cylindrical shape, a second shift portion 26A annularly charged with a second shift catalyst, and a second shift portion 26A. A selective oxidation section 36A is provided along the outer periphery of the cylinder.
[0065]
The second metamorphic portion 26A has an inner cylindrical body 29A provided coaxially with the outer wall of the medium / low temperature unit 3, and an inner cylindrical body 29A provided coaxially with the outer wall of the intermediate / low temperature unit 3 and provided on the outer peripheral side of the inner cylindrical body 29A. A cylindrical body 30A is provided. The catalyst filling layer 25A of the second shift section 26A is an annular space in which the second shift catalyst is accommodated, and is formed by the outer peripheral surface of the inner cylindrical body 29A and the inner peripheral surface of the middle cylindrical body 30A. The annular baffle plate 27A is installed in the gap between the first transformation portion 21 and the second transformation portion 26A, and a gas dispersion plate 34A is provided at the center of the ring.
[0066]
The gas introduction flow path 31A includes an annular baffle plate 27A, an inner circumferential surface on the first transformation portion 21 side of the middle cylindrical body 30A located inside the selective oxidation portion 36A, and a first transformation portion 21 side of the inner cylinder 29. This is a flow path for introducing the reformed gas that has passed through the first shift section 21 into the second shift section 26A in a space formed by the outer peripheral surface of the first shift section 21. The gas lead-out flow path 32A is opposed to the inner peripheral surface on the bottom surface 43 side of the intermediate cylindrical body 30A, the bottom surface 39 of the second shift section 26A, the inner peripheral surface of the inner cylinder body 29A, and the first shift section 21 of the selective oxidation section 36A. This is a flow path for introducing the reformed gas that has passed through the second shift section 26A into the selective oxidation section 36A in a space formed by the pipe line 70A that communicates with the section. The pipe line 70A is connected to one end of the inner cylindrical body 29A and is a cylindrical body having a circular cross section or a rectangular cross section that penetrates the middle cylindrical body 30A, and has a pipe diameter that does not hinder the flow of the gas introduction flow path 31A. . The pipe line 70A has a second opening 28A provided on the gas introduction flow path 71A side. The first opening 33A is provided at one end of the inner cylindrical body 29 located on the bottom surface 39 side of the middle cylindrical body 30A. The selective oxidation air introduction port 58 is disposed in the vicinity of the first opening 33A, and is preferably disposed in a state of being slightly inserted inside the first opening 33A. Since the selective oxidation air inlet 58 is installed in the vicinity of the first opening 33A, the reformed gas transformed in the second transformation section 26A and the selective oxidation air are appropriately mixed, The selective oxidation reaction in the selective oxidation unit 36A proceeds effectively.
[0067]
The selective oxidation unit 36A has a selective oxidation catalyst packed layer 35A formed by the inner peripheral surface of the medium / low temperature unit 3 and the outer peripheral surface of the middle cylindrical body 30A, and further includes a gas introduction channel 71A and a gas outlet channel 72A. Is provided. The gas introduction flow path 71A is a space formed by the inner peripheral surface of the medium / low temperature unit 3, the outer peripheral surface of the intermediate cylindrical body 30, and the annular baffle plate 27A, and selectively oxidizes the reformed gas that has passed through the second shift section 26A. It leads to the catalyst packed bed 35A. The gas dispersion plate 37A homogenizes the gas flow, and is provided in the gas introduction channel 71A. The gas lead-out flow path 72A is provided in the inner peripheral surface of the medium / low temperature unit 3, the outer peripheral surface of the intermediate cylindrical body 30A, the bottom surface 39 of the second shift section 26A, the bottom surface 43 of the medium / low temperature unit 3, and the reformed gas lead-out pipe 55. The reformed gas that has passed through the selective oxidation catalyst packed bed 35 A is guided to the reformed gas outlet pipe 55 in the space formed by the peripheral surface.
[0068]
In the second shift section 26A configured as described above, the reformed gas that has passed through the first shift section 21 passes through the gas introduction flow path 31A and the gas dispersion plate 34A in a downward flow, and then the catalyst packed bed. Pass 25A. Then, the reformed gas that has passed through the second shift catalyst packed bed 25A turns back at the first opening 33A, passes through the gas outlet passage 32A in an upward flow, and passes through the second opening 28A. Then, the gas is introduced to the selective oxidation unit 36A via the gas introduction channel 71A. That is, the reformed gas that has passed through the second shift section 26A passes through the gas introduction channel 71A and the gas dispersion plate 37A, then passes through the selective oxidation catalyst packed bed 35A in a downward flow, and further passes through the gas outlet channel. It is guided out of the system through 72A.
[0069]
When the second shift portion 26A and the selective oxidation portion 36A are configured concentrically as described above, the second shift portion 26A is located in the central portion where the amount of the reformed gas tends to increase. The reformed gas flows uniformly to the selective oxidation unit 36A located at the outer peripheral edge of 26A, and the selective oxidation reaction proceeds uniformly. Therefore, the amount of the selective oxidation catalyst filled in the selective oxidation unit 36A is optimized, and the temperature distribution is also optimized.
[0070]
In the first to fourth embodiments, the reformer upper part 2 as a high temperature unit is arranged on the upper side, and the reformer lower part 3 as a medium / low temperature unit is arranged on the lower side. However, the present invention is not limited to this, and the fuel reformer can be used upside down.
[0071]
In the first to fourth embodiments, the annular baffle plate 18 is provided in the gap between the reformer upper portion 2 and the reformer lower portion 3 so that the bottom surface of the reformer upper portion 2, the reformer Although the case where the heat exchange part 24 of the reformed gas and the reformed added water is formed by the upper surface of the lower part 3 and the connecting flow pipe 19 is shown, the present invention is not limited to this, and in short the first It suffices if the reformed additive water is evaporated and superheated and the optimum temperature distribution in each part can be achieved.
[0072]
For example, the bottom surface of the first metamorphic portion 21 is connected to the top surface of the second metamorphic portion 26 by a connecting flow pipe, and an annular baffle plate is provided in the gap between the coupling portions. You may provide the 2nd heat exchange part which performs heat exchange with reformed gas and the 1st reforming addition water by the upper surface of 2 shift part 26, and a connection distribution pipe. Further, the bottom surface of the second metamorphic portion 26 and the top surface of the selective oxidation portion 36 are connected by a connecting flow pipe, and an annular baffle plate is provided in the gap between the connection portions. A third heat exchanging unit that performs heat exchange between the reformed gas and the first reformed additive water can also be provided by the upper surface of the unit 36 and the connecting flow pipe. In the case where the third heat exchange unit is provided, an inlet for selective oxidation air may be installed inside the connecting flow pipe connecting the bottom surface of the second transformation unit 26 and the top surface of the selective oxidation unit 36. it can.
[0073]
【The invention's effect】
According to the fuel reformer of the present invention, a combustion chamber in which fuel is combusted, a high temperature unit provided on the outer peripheral surface side of the combustion chamber, and having a reforming section that is annularly filled with a reforming catalyst, and the high temperature Provided on the side connected to the unit, the shift portion filled with the shift catalyst cylindrically or annularly, and provided on the side opposite to the side connected to the high-temperature unit, and the selective oxidation catalyst cylindrically or annularly Because it has a structure with a medium and low temperature unit having a selective oxidation part filled with, it is divided into two parts of high temperature and low temperature, and the composition of the integrated fuel reformer is simplified and manufactured. Cost reduction and thermal efficiency can be improved.
Moreover, according to the fuel reformer of the present invention, the reformed gas that has passed through the reforming section of the high-temperature unit is connected to the connecting circulation pipe that supplies the reformed gas to the metamorphic section side of the medium-low temperature unit. Since the high-temperature unit and the container that integrally accommodates the medium-low temperature unit are provided, the generation of thermal stress can be remarkably reduced and the durability of the fuel reformer can be improved.
[0074]
Further, according to the fuel reformer of the present invention, the reformed / added water flow path formed in the gap between the outer wall of the high temperature unit and the medium / low temperature unit and the inner wall of the container, and the reformer for supplying the reforming raw material to the high temperature unit. When the mixing raw material supply path, the reforming / addition water flow path, and the reforming raw material supply path are connected to each other, the reforming / addition water is exchanged by heat exchange between the reforming / addition water path, the high temperature unit, and the medium / low temperature unit. Can be vaporized and superheated with the sensible heat of the reformed gas, and the high-temperature superheated steam of the reformed additive water generated can be used to preheat the fuel in the case of gaseous fuel and vaporize in the case of liquid fuel . Thus, the fuel reformer of the present invention can be applied to gas fuels such as city gas, LPG and anaerobic digestion gas, and liquid fuels such as kerosene and naphtha.
[0075]
Further, according to the fuel reformer of the present invention, the reforming material supply path for supplying the reforming material to the high temperature unit and the reforming addition water are directly supplied to the high temperature unit without passing through the medium / low temperature unit. When the second reformed / added water channel, the reformed / added water channel, the reforming raw material supply channel and the second reformed / added water channel are provided with a mixing chamber that communicates with each other, the start-up time is greatly shortened. Temperature control of each reaction part can be facilitated.
[0076]
Further, according to the fuel reformer of the present invention, the medium / low temperature unit is provided on the high temperature unit side, and has a first shift portion filled with the first shift catalyst in a cylindrical shape or an annular shape, A second shift section having a second shift section filled with a second shift catalyst in a ring, and the second shift section is positioned coaxially with respect to the selective oxidation section; The selective oxidation sections are arranged concentrically, and the entire reformer becomes compact.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a basic configuration of a first embodiment of the present invention.
FIG. 2 is a flowchart for explaining an operation procedure at the time of start-up in the apparatus of FIG.
FIG. 3 is a longitudinal sectional view for explaining a preheating state at the start-up in the apparatus of FIG.
4 is a longitudinal cross-sectional view illustrating a supply start state of a reforming raw material in the apparatus of FIG.
FIG. 5 is a longitudinal sectional view for explaining a supply start state of first reformed additive water in the apparatus of FIG. 1;
FIG. 6 is a configuration block diagram illustrating a second embodiment of the present invention.
FIG. 7 is a longitudinal sectional view showing a third embodiment of the present invention.
FIG. 8 is a longitudinal sectional view showing a fourth embodiment of the present invention.
[Explanation of symbols]
1 Reformer
2 Upper part of reformer (high temperature unit)
3 Lower part of reformer (medium / low temperature unit)
4 Burner
5 Combustion cylinder
6 Reformed catalyst packed bed
7 Modification section
8 Reformer inlet gas flow path
10 Combustion gas flow path
13 containers
14 Insulation
15 Bulkhead
16 Reformed gas flow path
17 Upper bottom of reformer
18 Baffle plate
19 Corrugated expansion and contraction pipe (connected distribution pipe)
20 First modified catalyst packed bed
21 First Transformation Department
24 Heat exchange section
25, 25A Second modified catalyst packed bed
26, 26A Second metamorphic part
28, 28A Middle cylinder upper end opening (second opening)
29, 29A inner cylinder
30, 30A Medium cylinder
31, 31A Gas introduction flow path
32, 32A Gas outlet channel
33, 33A Inner cylinder lower end opening (first opening)
35, 35A selective oxidation catalyst packed bed
36, 36A Selective oxidation part
40 1st reforming addition water channel (reforming addition water channel)
44 mixing chamber
45 Second modified additive water flow path
50 Fuel channel (reforming raw material supply channel)

Claims

A combustion chamber in which fuel is combusted, and a high temperature unit provided on the outer peripheral surface side of the combustion chamber and having a reforming section filled with a reforming catalyst in an annular shape;
Provided on the side connected to the high temperature unit, and is provided on the side opposite to the side connected to the high temperature unit and the shift portion filled with the shift catalyst in a cylindrical or annular shape, and is selected to be cylindrical or annular A medium to low temperature unit having a selective oxidation part filled with an oxidation catalyst;
A connected flow pipe for supplying the reformed gas that has passed through the reforming section of the high-temperature unit to the shift section side of the medium-low temperature unit;
A container that integrally accommodates the high temperature unit and the medium / low temperature unit connected by the connection flow pipe;
A reformed and added water flow path formed in a gap between the outer wall of the high temperature unit and the medium and low temperature unit and the inner wall of the container;
A reforming / adding water inlet provided on the side of the reforming / adding water channel opposite to the side connected to the high temperature unit of the medium / low temperature unit;
A reforming material supply path for supplying the reforming material to the high temperature unit;
A second reformed additive water flow path for supplying reformed additive water directly to the high temperature unit without passing through the medium / low temperature unit;
A mixing chamber in which the reforming / addition water channel, the reforming raw material supply channel, and the second reforming / addition water channel communicate with each other;
A fuel reformer comprising:

A baffle plate provided in a connecting portion gap between the high temperature unit and the medium / low temperature unit;
The heat exchange section provided on the opposing surface of the high temperature unit and the medium / low temperature unit, wherein the heat exchanges heat between the reformed gas sent from the high temperature unit to the medium / low temperature unit and the reformed additive water. With the exchange;
A fuel reformer according to claim 1 .

The connection flow pipe, the fuel reformer according to claim 1 or claim 2 characterized in that it has a telescoping member which expands and contracts in the axial direction of the connecting flow pipe.

The shift unit is provided on the high-temperature unit side, and is provided on the side of the selective oxidation unit and the first shift unit filled with the first shift catalyst in a cylindrical shape or an annular shape. The fuel reformer according to any one of claims 1 to 3 , further comprising a second shift section charged with the shift catalyst.

Further, the second metamorphic part is:
An inner cylindrical body provided coaxially with the outer wall of the medium-low temperature unit;
An intermediate cylinder that is coaxial with the outer wall of the medium-low temperature unit and is provided on the outer peripheral side of the inner cylinder;
And a gas introduction flow path for the reformed gas that has passed through the first metamorphic portion is formed by the inner peripheral surface of the inner cylindrical body; the outer peripheral surface of the inner cylindrical body and the inner peripheral surface of the middle cylindrical body 5. The fuel reformer according to claim 4 , wherein a catalyst packed bed of two metamorphic portions is formed; a gas outlet passage is formed by the outer peripheral surface of the middle cylindrical body and the inner peripheral surface of the medium-low temperature unit.

Further, the second metamorphic part is:
A first opening provided on the selective oxidation part side of the inner cylindrical body, and in communication with the gas introduction flow path and the catalyst packed bed of the second shift part;
A second opening provided on the side of the first transformation portion of the middle cylindrical body and in communication with the catalyst packed bed of the second transformation portion and the gas outlet passage;
A fuel reformer according to claim 5 .

The shift converter and a baffle plate disposed in a gap between the selective oxidation unit, of claims 1 to 6, characterized in that a inlet of inside air selective oxidation of the central opening of the baffle plate The fuel reformer according to any one of claims.

The selective oxidation unit, either of claims 1 to 7, characterized in that the tube-shaped hollow portion reformed gas is configured not to pass sent from the shift converter in the vicinity of the central portion is provided The fuel reformer according to claim 1.

The medium-low temperature unit is provided on the high-temperature unit side, and has a first shift portion filled with the first shift catalyst in a cylindrical shape or an annular shape, and a second shift shift that is filled with the second shift catalyst in a cylindrical shape or an annular shape. A metamorphic part having a part;
The fuel reformer according to any one of claims 1 to 3 , wherein the second metamorphic portion is positioned in a coaxial cylindrical shape with respect to the selective oxidation portion.

The second metamorphic portion includes an inner cylindrical body provided coaxially with the outer wall of the medium-low temperature unit, and an intermediate cylindrical body provided coaxially with the outer wall of the intermediate-low temperature unit and provided on the outer peripheral side of the inner cylindrical body. And having
A catalyst packed layer of the second shift section provided in a space formed by the outer peripheral surface of the inner cylindrical body and the inner peripheral surface of the middle cylindrical body;
A selective oxidation catalyst packed layer of the selective oxidation unit provided in a space formed by the outer peripheral surface of the intermediate cylindrical body and the inner peripheral surface of the medium-low temperature unit;
A gas introduction flow path formed at an opposing portion of the first shift section and the second shift section and allowing the reformed gas that has passed through the first shift section to flow into the second shift section;
A flow path connecting the bottom side of the second shift section and the first shift section facing portion of the selective oxidation section, and a gas outlet flow path for the reformed gas that has passed through the second shift section;
A fuel reformer according to claim 9 .

And a baffle plate provided at a facing portion between the first metamorphic portion and the second metamorphic portion;
The fuel reformer according to claim 10 , wherein the gas introduction flow path is formed by the baffle plate, an inner peripheral surface of the middle cylindrical body, and an outer peripheral surface of the inner cylindrical body.

Said gas outlet passage, claim 10 formed by a conduit communicating a bottom in said cylinder, an inner circumferential surface of the inner cylinder, and the inner peripheral surface of the inner cylindrical body and said selective oxidation unit The fuel reformer described in 1.

The fuel reformer according to any one of claims 1 to 12 , wherein a vacuum heat insulating layer is provided on an outer periphery of the container.

A combustion chamber in which fuel burns, and a high-temperature unit provided on the outer peripheral surface side of the combustion chamber and having a reforming section filled with a reforming catalyst;
A mid-low temperature unit having a reforming unit that transforms the reformed gas that has passed through the reforming unit of the high-temperature unit, and a selective oxidation unit that selectively oxidizes the reformed gas reformed in the transforming unit;
A reforming / addition water flow path in which the reforming / adding water is arranged so that heat exchange is possible in the medium / low temperature unit, and the reforming addition water is supplied to the high temperature unit;
A second reformed additive water flow path for supplying reformed additive water directly to the high temperature unit without passing through the medium / low temperature unit;
A reforming material supply path for supplying the reforming material to the high temperature unit;
A mixing chamber in which the reforming / addition water channel, the second reforming / addition water channel and the reforming material supply channel communicate with each other;
A fuel reformer comprising: