JP3544953B2 - Waste treatment method and gasification and melting equipment - Google Patents

Description

ガス化効率の最も高い組合せは、Ｎｏ．１の組合せであるが酸素消費量が多いのでコスト高である。酸素消費量、次に水蒸気消費量を少なくする順に、ガス化効率が低下するが、コストも低くなる。本発明において使用される酸素は、高純度のものでも良く、また酸素富化膜を使用して得られる低純度のものでも良い。Ｎｏ．９の空気と空気の組合せは、従来の焼却炉の燃焼空気として公知であるが、流動層炉の水平断面を円形とした本発明においては、炉内周辺部上方に設けられる傾斜壁の下方投影面積が、流動層炉の水平断面を矩形とする場合の傾斜壁の下方投影面積より大きいので、周辺流動化ガスの流量を増大し、従って、酸素供給量を増大できるので、ガス化効率を向上させることができる。
【００１４】
好ましくは、本発明の方法は、流動化ガスが炉底中央部と炉底周辺部の間の炉底中間部から炉内へ供給される中間流動化ガスを更に含む。中間流動化ガスの質量速度は、中央流動化ガスの質量速度と周辺流動化ガスの質量速度の間にある。中間流動化ガスは、水蒸気と空気の混合気体、及び空気の２種の気体の内の１つである。それ故、中央流動化ガス、中間流動化ガス、及び周辺流動化ガスの組合せは、１８通りとなるが、酸素含有量は、炉の中心部から周辺部へ順に増加することが好都合であり、好適な組合せは、第２表の１５通りである。
【００１５】
【表２】

第２表の組合せにおいて、どれを選定するかは、ガス化効率を重視するか、経済性を重視するかにより、決められる。第２表の組合せの内、ガス化効率の最も高い組合せは、Ｎｏ．１の組合せであるが、酸素消費量が多いのでコスト高である。酸素消費量、次に水蒸気消費量を少なくする順に、ガス化効率が低下するが、コストも低くなる。第１表及び第２表において使用される酸素は、高純度のものでも良く、また酸素富化膜を使用して得られる低純度のものでも良い。
【００１６】
流動層炉が大型となる場合、中間流動化ガスは、炉底中央部と炉底周辺部の間に設けた複数の同心状の中間部から供給される複数の流動化ガスであることが好ましい。この場合、流動化ガスの酸素濃度は、炉中央部において最も低く、周辺部に近づくに従ってより高くするのが好適である。
【００１７】
本発明の方法において、好ましくは、流動層炉へ供給される流動化ガスは、可燃物の燃焼に必要な理論燃焼空気量の３０％以下の空気量を含む。流動層炉の炉底周辺部付近から不燃物が取出され、分級され、得られた砂が流動層炉内へ戻される。流動層炉で生成された可燃ガス及び微粒子が熔融燃焼炉で１３００℃以上で高温燃焼され、灰分が熔融される。熔融燃焼炉からの排ガスによりガスタービンが駆動される。流動層炉内の圧力は、用途に応じて大気圧以下又は大気圧以上に維持される。可燃物は、廃棄物、石炭、その他である。
【００１８】
本発明は、また流動層炉において可燃物がガス化される装置を提供する。本発明の装置において、流動層炉は、水平断面がほぼ円形の側壁、炉内底部に配置される流動化ガス分散機構、流動化ガス分散機構の外周に配置される不燃物取出口、流動化ガス分散機構の中央部付近から炉内へ流動化ガスを垂直方向上方へ流動するように供給する中央供給手段、流動化ガス分散機構の周辺部から炉内へ流動化ガスを垂直方向上方へ流動するように供給する周辺供給手段、周辺供給手段から垂直方向上方へ流動する流動化ガスを炉中央部へ転向させる傾斜壁、及び傾斜壁の上方に配置されるフリーボードを含み、中央供給手段は、質量速度が比較的小さく、酸素濃度が比較的低い流動化ガスを供給し、周辺供給手段は、質量速度が比較的大きく、酸素濃度が比較的高い流動化ガスを供給する。
【００１９】
本発明の装置においては、流動化ガス分散機構の中央部と周辺部の間のリング状中間部から炉内へ流動化ガスを垂直方向上方へ供給する中間供給手段が設けられる。中間供給手段は、中央供給手段と周辺供給手段から供給される流動化ガスの質量速度の中間の質量速度、及び中央供給手段と周辺供給手段から供給される流動化ガスの酸素濃度の中間の酸素濃度の流動化ガスを供給する。周辺供給手段は、リング状の供給ボックスにより形成されることができる。可燃物入口が流動層炉の上方に配置され、可燃物入口は、可燃物を中央供給手段の上方へ落下させ、流動化ガス分散機構は、中央部よりも周辺部が低く形成されることができる。
【００２０】
不燃物取出口は、分散機構の外周に配置されるリング部分とリング状部分から下方へ向かって縮小する円錐状部分を有することができる。不燃物取出口は、直列に配列される定量排出器、第１シール用スイング弁、スイングカット弁、及び第２シール用スイング弁を有することができる。
【００２１】
本発明の装置は、流動層炉において発生された可燃ガス及び微粒子を高温燃焼させ灰分を熔融させる熔融燃焼炉を含むことができる。熔融燃焼炉は、ほぼ垂直方向の軸線を有する円筒形一次燃焼室、円筒形一次燃焼室へ前記流動層炉で発生された可燃ガス及び微粒子を軸線のまわりに旋回するように供給する可燃ガス入口、円筒形一次燃焼室に連通される二次燃焼室、二次燃焼室の下方部分に設けられ熔融灰分を排出可能な排出口を有する。熔融燃焼炉の二次燃焼室の排ガスが、廃熱ボイラ及び空気予熱器導入され、廃熱が回収される。熔融燃焼炉の二次燃焼室の排ガスによりガスタービンを駆動させることができる。排ガスは、集塵器に導入され塵埃が除去された後に大気中へ放出されることができる。熔融燃焼炉の二次燃焼室の排ガスは、廃熱ボイラ及び空気予熱器導入され、廃熱が回収され得る。熔融燃焼炉の二次燃焼室の排ガスによりガスタービンを駆動させることができる。排ガスは、集塵器に導入され塵埃が除去された後に大気中へ放出される。
【００２２】
【作用】
本発明のガス化装置は、流動層炉の循環流により熱が拡散されるので、高負荷とすることができ、炉を小型にすることができる。
本発明においては、流動層炉が少量の空気で燃焼を維持できるので、流動層炉を低空気比低温度（４５０〜６５０℃）とし、発熱を最小限に抑えて、ゆるやかに燃焼させることにより、可燃分を多量に含む均質な生成ガスを得ることができ、ガス、タール、チャーの可燃分の大部分を次段の熔融燃焼炉において利用できる。
本発明においては、流動層炉の循環流により大きな不燃物も容易に排出できる。また、不燃物中の鉄、アルミが、未酸化の有価物として利用できる。
本発明の方法又は装置においては、流動層炉の水平断面がほぼ円形にされるから、炉を耐圧構造とし、流動層炉を大気圧以上の加圧状態とし、炉内へ供給される可燃物から生成される可燃ガスの圧力を高圧とすることが容易である。高圧の可燃ガスは、高効率で運転できるガスタービンやボイラ・ガスタービン複合プラント用の燃料として使用可能であり、それ故、そのようなプラントにおいて可燃ガスを使用することにより、可燃物からのエネルギ回収の効率を向上できる。本発明の方法又は装置において、ごみ処理を主体とする場合は、臭気や有害燃焼ガスが流動層炉から漏れるのを防止するため、炉内圧を大気圧以下とすることが好ましいが、この場合にも流動層炉の水平断面が円形であることにより、炉壁は、容易に外圧に耐えることができる。
【００２３】
本発明においては、流動層炉へ供給される中央流動化ガスの質量速度が、周辺流動化ガスの質量速度より小にされ、炉内周辺部上方における流動化ガスの上向き流が炉の中央部へ向うように転向され、それによって、流動媒体の沈降拡散する移動層が炉の中央部に形成されると共に、炉内周辺部に流動媒体が活発に流動化している流動層が形成される。炉内へ供給された可燃物は、移動層の下部から流動層へ及び流動層頂部から移動層へ、流動媒体と共に循環する間に可燃ガスにガス化される。可燃物は、最初に、炉中央の下降する移動層の中で、主として揮発分が流動媒体（一般的には、硅砂を使用）の熱によりガス化される。そして、移動層を形成する中央流動化ガスの酸素含有量が、小さため、移動層内で生じた可燃ガスは、ほとんど燃焼されずに中央流動化ガスと共にフリーボードへ上昇され、発熱量の高い良質の生成ガスとなる。
【００２４】
移動層において揮発分が失われ加熱された可燃物、即ち、固定炭素（チャー）やタール分等は、次に流動層内へ循環され、流動層内の比較的酸素含有量の多い周辺流動化ガスと接触し燃焼され、燃焼ガス及び灰分に変わると共に炉内を４５０〜６５０℃に維持する燃焼熱を発生する。この燃焼熱により流動媒体が加熱され、加熱された流動媒体が炉周辺部上方で炉中央部へ転向され移動層内を下降することにより移動層内の温度を揮発分のガス化に必要な温度に維持する。可燃物が投入される炉中央部ほど低酸素状態であるので、高い可燃分を有する生成ガスを発生することができる。また、可燃物中の金属が不燃物取出口から未酸化の有価物として回収することができる。
【００２５】
本発明においては、流動層炉において生成されたガス及び灰分その他の微粒子を熔融燃焼炉において燃焼させる場合、生成ガスが高可燃分を含むので、加熱用燃料を必要とすることなく、熔融炉内を１３００℃以上の高温にすることができ、熔融炉内で灰分を充分熔融させることができる。熔融した灰は、熔融炉から取り出し水冷等の周知の方法により容易に固化させ得る。それ故、灰分の体積は、著しく減少され、また灰分中の有害金属は、固化されるので、灰分は、埋め立て処理可能な形態となる。本発明のその他の作用は、特許請求の範囲及び図面を参照する実施例の説明から明らかにされる。
【００２６】
【実施例】
以下、本発明の実施例を図面を参照して説明するが、本発明は、これらに限定されるものではなく、特許請求の範囲によって定義されるものである。また、図１から図１４において、同一の符号が付された部材は、同一部材又は対応する部材であり、各図面の説明において、重複した説明は、省略される。
【００２７】
図１は、本発明のガス化方法を実施する第１実施例のガス化装置の主要部の図解的な縦断面図、図２は、図１のガス化装置の図解的な水平断面図である。図１に示されるガス化装置において、流動層炉２内へ炉底に配置される流動化ガス分散機構１０６を介し供給される流動化ガスは、炉底中央部４付近から炉内へ上向き流として供給される中央流動化ガス７及び炉底周辺部３から炉内へ上向き流として供給される周辺流動化ガス８から成る。
【００２８】
第１表に示すように、中央流動化ガス７は、水蒸気、水蒸気と空気の混合気体、及び空気の３種の気体の内の１つであり、周辺流動化ガス８は、酸素、酸素と空気の混合気体、及び空気の３種の気体の内の１つである。中央流動化ガスの酸素含有量は、周辺流動化ガスの酸素含有量以下とされる。流動化ガス全体の空気量が、可燃物１１の燃焼に必要な理論燃焼空気量の３０％以下とされ、炉内は、還元雰囲気とされる。
【００２９】
中央流動化ガス７の質量速度は、周辺流動化ガス８の質量速度より小にされ、炉内周辺部上方における流動化ガスの上向き流がデフレクタ６により炉の中央部へ向うように転向される。それによって、炉の中央部に流動媒体（一般的には硅砂を使用）が沈降拡散する移動層９が形成されると共に炉内周辺部に流動媒体が活発に流動化している流動層１０が形成される。流動媒体は、矢印１１８で示すように、炉周辺部の流動層１０を上昇し、次にデフレクタ６により転向され、移動層９の上方へ流入し、移動層９中を下降し、次に矢印１１２で示すように、ガス分散機構１０６に沿って移動し、流動層１０の下方へ流入することにより、流動層１０と移動層９の中を矢印１１８及び１１２で示すように循環する。
【００３０】
可燃物供給口１０４から移動層９の上部へ供給された可燃物１１は、流動媒体と共に移動層９中を下降する間に、流動媒体の持つ熱により加熱され、主として揮発分がガス化される。移動層９には、酸素が無いか少ないため、ガス化された揮発分から成る生成ガスは燃焼されないで、移動層９中を矢印１１６のように抜ける。それ故、移動層９は、ガス化ゾーンＧを形成する。フリーボード１０２へ移動した生成ガスは、矢印１２０で示すように上昇し、ガス出口１０８から生成ガス２９として排出される。
【００３１】
移動層９でガス化されない、主としてチャー（固定炭素分）やタール１１４は、移動層９の下部から、流動媒体と共に矢印１１２で示すように炉内周辺部の流動層１０の下部へ移動し、比較的酸素含有量の多い周辺流動化ガス８により燃焼され、部分酸化される。流動層１０は、可燃物の酸化ゾーンＳを形成する。流動層１０内において、流動媒体は、流動層内の燃焼熱により加熱され高温となる。高温になった流動媒体は、矢印１１８で示すように、傾斜壁６により反転され、移動層９へ移り、再びガス化の熱源となる。流動層１０の温度は、４５０〜６５０℃に維持され、抑制された燃焼反応が継続するようにされる。
【００３２】
図１及び図２に示すガス化炉１によれば、流動層炉２にガス化ゾーンＧと酸化ゾーンＳが形成され、流動媒体が両ゾーンにおいて熱伝達媒体となることにより、ガス化ゾーンＧにおいて、発熱量の高い良質の可燃ガスが生成され、酸化ゾーンＳにおいては、ガス化困難なチャーやタール１１４を効率良く燃焼させることができる。それ故、可燃物のガス化効率を向上させることができ、良質の可燃ガスを生成することができる。
【００３３】
図２に示される流動層炉２の水平断面において、ガス化ゾーンＧを形成する移動層９は、炉中心部において円形であり、酸化ゾーンＳを形成する流動層１０は、移動層９のまわりにリング状に形成される。流動層１０の外周にリング状の不燃物排出口５が配置される。ガス化炉１を円筒形とすることにより、高い炉内圧を容易に支持することができる。ガス化炉自体により炉内圧を受ける構造に代えて、ガス化炉の外部に別途圧力容器（図示しない）を設けることができる。
【００３４】
図３は、本発明のガス化方法を実施する第２実施例のガス化装置の主要部の図解的な縦断面図、図４は、図３のガス化装置の図解的な水平断面図である。図３に示される第２実施例のガス化装置において、流動化ガスは、中央流動化ガス７及び周辺流動化ガス８に加え、炉底中央部と炉底周辺部の間の炉底中間部から炉内へ供給される中間流動化ガス７’を含む。中間流動化ガス７’の質量速度は、中央流動化ガス７の質量速度と周辺流動化ガス８の質量速度の間に選定される。中間流動化ガスは、水蒸気、水蒸気及び空気の混合気体、又は空気の３種の気体の内のいずれか１つである。
【００３５】
図３のガス化装置において、図１のガス化装置の場合と同様に、中央流動化ガス７は、水蒸気、水蒸気と空気の混合気体、及び空気の３種の気体の内の１つであり、周辺流動化ガス８は、酸素、酸素と空気の混合気体、及び空気の３種の気体の内の１つである。中間流動化ガスの酸素含有量は、中央流動化ガスの酸素含有量と周辺流動化ガスの酸素含有量の間に選定される。それ故、流動化ガスの好適な組合せは、第２表の１５通りである。各組合せにおいて、流動層炉の中央部から周辺部へ拡がっていくにつれて、酸素供給量が増加することが重要である。流動化ガス全体の空気量が、可燃物１１の燃焼に必要な理論燃焼空気量の３０％以下とされ、炉内は、還元雰囲気とされる。
【００３６】
図１のガス化装置の場合と同様に、図３のガス化装置において、炉の中央部に流動媒体が沈降する移動層９が形成され、炉の周辺部に流動媒体が上昇する流動層１０が形成される。流動媒体が、矢印１１２及び１１８で示すように移動層及び流動層を通り循環する。移動層９と流動層１０の間においては、流動媒体が、主として横方向に拡散する中間層９’が形成される。移動層９及び中間層９’がガス化ゾーンＧを形成し、流動層１０が酸化ゾーンＳを形成する。
【００３７】
移動層９の上部へ投入された可燃物１１は、流動媒体と共に移動層９中を下降する間に加熱され、その揮発分がガス化する。移動層９中でガス化されなかったチャー及びタール並びに一部の揮発分は、流動媒体と一緒に中間層９’及び流動層１０へ移動し、部分的にガス化し部分的に燃焼される。中間層９’でガス化されない主としてチャー及びタールは、流動媒体と共に、炉周辺部の流動層１０内へ移動し、比較的酸素含有量の多い周辺流動化ガス８中で燃焼される。流動媒体は、流動層１０中で加熱され、移動層９へ循環し、移動層９中の可燃物を加熱する。中間層の酸素濃度については、可燃物の種類（揮発分が多いか、チャー、タール分が多いか）等により、酸素濃度を低くしてガス化を主体にするか、酸素濃度を高くして酸化燃焼を主体にするかが選定される。
【００３８】
図４に示す流動層炉の水平断面おいて、ガス化ゾーンを形成する移動層９は、炉中心部において円形であり、その外周に沿って中間流動化ガス７’により形成される中間ゾーン９’があり、酸化ゾーンを形成する流動層１０は、中間ゾーン９’のまわりにリング状に形成される。流動層１０の外周にリング状の不燃物排出口５が配置される。ガス化炉１を円筒形とすることにより、高い炉内圧を容易に支持することができる。炉内圧は、ガス化炉自体で受けるか、またはガス化炉の外部に別途圧力容器を設けてそれにより受けることができる。
【００３９】
図５は、本発明の第３実施例のガス化装置の図解的な垂直断面図である。図５のガス化装置１において、ごみ等の可燃物からなるガス化原料１１は、ダブルダンパー１２、圧縮フィーダ１３、及び給塵フィーダ１４により、ガス化装置１の流動層炉２へ供給される。圧縮フィーダ１３は、ガス化原料をプラグ状に圧縮し、これにより炉内圧がシールされる。プラグ状に圧縮されたごみは、図示しないほぐし器によりばらばらにされ、給塵フィーダ１４により炉内へ送られる。
【００４０】
図５のガス化装置において、中央流動化ガス７及び周辺流動化ガス８は、図１の実施例と同様に供給され、それ故、図１の実施例と同様に、流動層炉２に還元雰囲気のガス化ゾーンと酸化ゾーンが形成される。流動媒体が両ゾーンにおいて熱伝達媒体となり、ガス化ゾーンにおいて、発熱量の高い良質の可燃ガスが生成され、また酸化ゾーンにおいて、ガス化困難なチャーやタール１１４が効率良く燃焼され、高いガス化効率と良質の可燃ガスが得られる。図５の実施例において、ダブルダンパ１２とガス化炉１のフリーボード１０２に連通するルーツブロア１５が設けられ、ごみの圧縮が不十分な場合に炉内から圧縮フィーダを通りダブルダンパ１２へリークするガスを炉内へ戻す。好ましくは、ルーツブロア１５は、ダブルダンパ１２の上段部分が大気圧になるように、適当な量の空気及びガスをダブルダンパ１２から吸引し炉内へ戻す。
【００４１】
図５のガス化装置において、流動層炉２から不燃物を排出するため、不燃物排出口５、円錐形シュート１６、定量排出器１７、シール用第１スイング弁１８、スイングカット弁１９、シール用第２スイング弁２０、トロンメル付き排出器２３が、順に配置され、次のように作動される。
【００４２】
（１）シール用第１スイング弁１８が開にされ、第２スイング弁２０が閉にされて炉内圧が第２スイング弁２０でシールされる状態において、定量排出器１７が運転され、流動媒体の砂を含む不燃物が、円錐形シュート１６内からスイングカット弁１９へ排出される。（２）スイングカット弁１９が所定量の不燃物を受けると、定量排出器１７がＯＦＦされ、第１スイング弁１８が閉にされて炉内圧が第１スイング弁１８でシールされる。そして排出弁２２が開にされスイングカット弁１９内が大気圧に戻される。次に第２スイング弁２０が完全に開にされ、そしてスイングカット弁１９が開にされることにより、不燃物がトロンメル付き連続排出器２３へ排出される。（３）第２スイング弁２０が完全に閉にされた後に、均圧弁２１が開にされ、第１スイング弁１８の内部と円錐形シュート１６の内部が均圧にされてから、第１スイング弁１８が開にされ、最初の工程（１）へ戻る。これらの工程（１）〜（３）は、自動的に繰り返し運転される。
【００４３】
トロンメル付き連続排出器２３は、連続運転され、大きな不燃物２７をトロンメルにより系外へ排出し、砂と小さな不燃物を砂循環エレベータ２４により輸送し、分級器２５により微細な不燃物２８を除去した後、砂は、ロックホッパ２６を介しガス化炉１へ戻される。このような不燃物排出機構は、２台のスイング弁が不燃物を受けずに圧力シール機能だけ有するので、第１及び第２スイング弁１８、２０のシール部における不燃物の噛込みを避けることができる。炉内圧が若干負圧でよい場合は、シール機能は不要である。
【００４４】
図６は、本発明の第４実施例のガス化装置の図解的な垂直断面図である。図６のガス化装置において、ガス化原料１１の供給とそれに関係する炉内圧のシールは、図５の不燃物の排出のための機構と同様に、スイングカット弁１９、１９’及びシール用第１及び第２スイング弁１８の組合せを使用して行われる。圧縮フィーダ１３は、除かれている。図６の実施例において、炉内から第１スイング弁１８内へ漏れたガスは、排出弁２２及びブロア（図示しない）を介し、炉内へ戻される。また、第１スイング弁１８を完全に閉じた後に均圧弁２１が開とされ、スイングカット弁１９内の圧力が炉内圧と同じにされる。
【００４５】
図７は、本発明のガス化装置により製造される生成ガスの精製工程の１例を示すフロー図である。図７の精製工程において、ガス化装置１へガス化原料１１及び流動化ガス７、８がガス化炉１へ供給される。ガス化装置１において生成された可燃生成ガスは、廃熱ボイラ３１で熱が回収され冷却されて、サイクロン分離器３２へ送られ、固形分３７、３８が分離される。その後、生成ガスは、水洗浄塔３３において水により洗浄され冷却され、アルカリ洗浄塔３４において硫化水素を除去され、その後、ガスホルダー３５に貯留される。サイクロン分離器３２で分離された固形分の内の未反応チャー３７は、ガス化装置１へ戻され、残りの固形分３８は、系外へ排出される。図５の実施例と同様に、ガス化装置１から排出された不燃物の内、大きな不燃物２７は、系外へ排出され、砂は、ガス化装置１へ戻される。洗浄塔３３、３４から出る廃水は、廃水処理器３６へ導入され、無害化処理される。
【００４６】
図８は、ガス化装置１において発生した可燃生成ガス及び微粒子が、熔融燃焼炉４１に導入されて高温燃焼され、灰が熔融される工程の１例を示すフロー図である。図８の工程において、ガス化装置１で製造された可燃分の多い生成ガスが、熔融燃焼炉４１へ導入される。熔融燃焼炉４１には、酸素、酸素と空気の混合気体、又は空気が吹き込まれ、生成ガス及び微粒子が１３００℃以上で燃焼され、灰が熔融され、またダイオキシン、ＰＣＢ等の有害物質が分解される。熔融燃焼炉４１で熔融された灰４４は、急冷されスラグとされ減量化される。熔融燃焼炉４１で発生した燃焼排気ガスは、スクラバー４２で急冷され、ダイオキシンの再合成が防止される。スクラバー４１で急冷された排気ガスは、フィルター４３において更に塵埃３８が除去され、排気塔５５から大気へ排出される。
【００４７】
図９は、本発明の第５実施例のガス化及び熔融燃焼装置の垂直断面斜視図である。図９において、ガス化装置１は、図１の実施例とほぼ同一であるが、ガス出口１０８は、熔融燃焼炉４１の可燃ガス入口１４２に連通されている。熔融燃焼炉４１は、ほぼ垂直方向の軸線を有する円筒形一次燃焼室１４０、及び水平方向に傾斜する二次燃焼室１５０を含む。流動層炉２で発生された可燃ガス１２０及び微粒子は、可燃ガス入口１４２を介し一次燃焼室１４０へその軸線のまわりに旋回するように供給される。
【００４８】
一次燃焼室１４０は、上端に始動バーナを備えると共に、燃焼用空気を軸線のまわりに旋回するように供給する複数の空気ノズル１３４を備える。二次燃焼室１５０は、一次燃焼室１４０とその下端で連通されると共に、二次燃焼室の下方部分に配置され熔融灰分を排出可能な排出口１５２、排出口１５２の上方に配置される排気口１５４、一次燃焼室と連通する部分の付近に配置される助燃バーナ１３６、及び燃焼用空気を供給する空気ノズル１３４を備える。排気口１５４は、輻射板１６２を備え、輻射により排気口１５４から失われる熱量を減少させている。
【００４９】
図１０は、廃熱ボイラ及びタービンと組み合わせて使用される本発明の実施例の流動層ガス化及び熔融燃焼装置の配置図である。図１０において、ガス化装置１は、排出器２３から排出された大きな不燃物２７及び分級器２５から排出された微細な不燃物２８を一緒に搬送するコンベヤ１７２を具備する。流動層炉２の下部から不燃物を取り出す円錐形シュート１６のまわりに空気ジャケット１８５が配置され、高温の抜き出し砂により空気ジャケット１８５内の空気が加熱される。補助燃料Ｆが、熔融燃焼炉４１の一次及び二次燃焼室１４０、１５０へ供給される。熔融燃焼炉４１の排出口１５２から排出される熔融状態の灰４４は、水室１７８に受け入れられ急冷されて、スラグ１７６として排出される。
【００５０】
図１０において、熔融燃焼炉４１から排出される燃焼ガスは、廃熱ボイラ３１、エコノマイザ１８３、空気予熱器１８６、集塵器４３、誘引通風機５４を経て大気へ排出される。空気予熱器１８６から出た燃焼ガスは、集塵器４３に入る前に、消石灰等の中和剤Ｎを添加される。水Ｗがエコノマイザ１８３へ供給され、予熱された後、ボイラ３１で加熱されて蒸気にされ、蒸気タービンＳＴを駆動する。空気Ａが空気予熱器１８６へ供給され、加熱された後、空気ジャケット１８５で更に加熱され、空気管１８４を介し、熔融燃焼炉４１、及び必要に応じてフリーボード１０２へ供給される。
【００５１】
廃熱ボイラ３１、エコノマイザ１８３、及び空気予熱器１８６の底部に溜まる微粒子１８０、１９０は、砂循環エレベータ２４で分級器２５へ搬送され微細な不燃物２８が除去され、流動層炉２へ戻される。フィルター４３において分離される飛灰３８は、高温で揮散したＮａ、Ｋなどのアルカリ金属塩を含むので、処理器１９４において薬品により処理される。
【００５２】
図１０の装置においては、流動層炉２の燃焼が低空気比による低温部分燃焼とされ、流動層温度が４５０℃〜６５０℃に維持されることにより、高熱量の可燃ガスを発生させることができる。また、低空気比により還元雰囲気で燃焼が行われるので、不燃物中に鉄、アルミが未酸化の有価物として得られる。流動層炉２で発生された高熱量の可燃ガス及びチャーは、熔融燃焼炉４１において、１３００℃以上の高温燃焼することができ、灰を熔融させ、ダイオキシンを分解させることができる。
【００５３】
図１１は、ガス冷却室２８０と組み合わせて使用される本発明の実施例の流動層ガス化及び熔融燃焼装置の配置図である。図１１において、ガス化装置１、熔融燃焼炉４１、水室１７８、集塵器４３、誘引通風機５４等は、図１０と同様である。図１１においては、廃熱ボイラに代えて、ガス冷却器２８０、独立空気予熱器１８８が設けられ、熔融燃焼炉４１から高温燃焼排ガスを耐火断熱被覆された高温ダクト２７８を介してガス冷却器２８０に導入する。ガス冷却器２８０において、燃焼ガスは、微細水噴霧により、瞬時に減温され、ダイオキシンの再合成が防止される。高温ダクト２７８の排ガス流速は、５ｍ／秒以下の低速とされる。ガス冷却器２８０の上部に温水発生器２８３が配置される。空気予熱器１８８で加熱された空気がガス化炉１のフリーボード１０２及び熔融燃焼炉４１へ供給される。
【００５４】
図１２は、廃熱ボイラ３１及び反応塔３１０と組み合わせて使用される本発明の実施例の流動層ガス化及び熔融燃焼装置の配置図である。図１２において、ガス化装置１、熔融燃焼炉４１、水室１７８、廃熱ボイラ３１、蒸気タービンＳＴ、エコノマイザ１８３、空気予熱器１８６、集塵器４３、誘因通風機５４等は、図１０と同様である。図１２においては、廃熱ボイラ３１とエコノマイザ１８３の間に、反応塔３１０、スーパーヒータ加熱燃焼器３２０が配置される。反応塔３１０において、消石灰スラリー等の中和剤Ｎが燃焼排ガスに添加され、ＨＣｌが除去される。反応塔３１０から排出される固体微粒子３１２は、廃熱ボイラ３１から排出される固体微粒子１８０と一緒に砂循環エレベータ２４により分級器２５へ送られる。加熱燃焼器３２０において、未燃焼ガス及び補助燃料Ｆを燃焼させ、蒸気温度を５００℃程度に上げる。図１２の装置においては、蒸気が高温高圧であることと、空気比が小さく排ガスの持ち出し顕熱が小さいことにより、発電効率を約３０％とすることができる。
【００５５】
図１３は、本発明の実施例のガス化コジェネレーション型の流動層ガス化及び熔融燃焼装置の配置図である。図１３において、ガス化装置１、熔融燃焼炉４１、水室１７８、廃熱ボイラ３１、集塵器４３、誘引通風機５４等は、図１０の装置と同様である。図１３においては、廃熱ボイラ３１と集塵器４３の間に反応塔３１０が配置され、反応塔３１０において、消石灰スラリー等の中和剤Ｎが燃焼排ガスに添加され、ＨＣｌが除去される。反応塔３１０の排ガスが、集塵器４３を経てガスタービン４２０で使用される。ガスタービン４２０においては、空気Ａが圧縮機Ｃにより圧縮され燃焼器ＣＣに供給され、燃焼器ＣＣにおいて燃料Ｆが燃焼され、この燃焼ガス及び圧縮機４１０で圧縮されて燃焼器ＣＣへ供給され排ガスが、タービンＴの作動流体となる。ガスタービン４２０の排気ガスは、スーパーヒータ４３０、節炭器４４０、及び空気予熱器４５０を順に通過され、誘因通風機５４により大気へ放出される。廃熱ボイラ３１において発生された蒸気が、スーパーヒータ４３０において、ガスタービン４２０の排気ガスにより加熱され、蒸気タービンＳＴへ供給される。
【００５６】
図１４は、本発明の実施例の加圧ガス化複合発電型の流動層ガス化及び熔融燃焼方法の工程を示すフロー図である。加圧型のガス化炉１で生成された高温高圧の生成ガス２９は、廃熱ボイラ３１’へ導入され、蒸気を発生させると共にそれ自体は冷却される。廃熱ボイラを出た生成ガスは、２分され、一方が熔融燃焼炉４１へ他方が中和剤Ｎを添加されＨＣｌが中和されて集塵器４３’へ導入される。集塵器４３’において、温度低下により固化した生成ガス中の低融点物質が、生成ガスから分離されて熔融燃焼炉４１へ送られ、熔融される。低融点物質が除去された生成ガスが、ガスタービンＧＴにおいて燃料ガスとして利用される。ガスタービンＧＴの排気ガスは、スーパーヒータＳＨ、エコノマイザＥＣｏで熱交換され、その後、排ガス処理器５１０で処理され、大気中へ放出される。熔融燃焼炉４１の排気ガスは、熱交換器ＥＸ、集塵器４３を経て、排ガス処理器５１０へ導入される。熔融炉から排出された熔融灰４４は、急冷しスラグにされる。集塵器４３から排出された固形分３８は、処理器１９４において薬品処理される。
【００５７】
図１４の工程によれば、廃棄物から生成されたガスが、ＨＣｌ及び固形分が除去された後、燃料として使用されるから、ガスタービンを腐食させるることがなく、また、ＨＣｌが除去されているので、ガスタービン排気ガスにより高温の蒸気を発生させることができる。
【００５８】
【発明の効果】
（１）本発明のガス化装置は、流動層炉の循環流により熱が拡散されるので、高負荷とすることができ、炉を小型にすることができる。
【００５９】
（２）本発明においては、流動層炉が少量の空気で燃焼を維持できるので、流動層炉を低空気比低温度（４５０〜６５０℃）とし、発熱を最小限に抑えて、ゆるやかに燃焼させることにより、可燃分を多量に含む均質な生成ガスを得ることができ、ガス、タール、チャーの可燃分の大部分を次段の熔融燃焼炉において利用できる。
【００６０】
（３）本発明においては、流動層炉の循環流により大きな不燃物も容易に排出できる。また、不燃物中の鉄、アルミが、未酸化の有価物として利用できる。
【００６１】
（４）本発明によれば、ごみ処理を無害化し、高いエネルギ利用率を有する方法又は設備が提供される。
【図面の簡単な説明】
【図１】本発明の第１実施例のガス化装置の主要部の図解的な垂直断面図。
【図２】図１のガス化装置の流動層炉の図解的な水平断面図。
【図３】本発明の第２実施例のガス化装置の主要部の図解的な垂直断面図。
【図４】図２のガス化装置の流動層炉の図解的な水平断面図。
【図５】本発明の第３実施例のガス化装置の図解的な垂直断面図。
【図６】本発明の第４実施例のガス化装置の図解的な垂直断面図。
【図７】生成ガスの精製工程の１例を示すフロー図。
【図８】灰が熔融される工程の１例を示すフロー図。
【図９】本発明の第５実施例のガス化及び熔融燃焼装置の図解的な垂直断面斜視図。
【図１０】廃熱ボイラ及びタービンと組み合わせて使用される本発明の実施例の流動層ガス化及び熔融燃焼装置の配置図。
【図１１】ガス冷却室と組み合わせて使用される本発明の実施例の流動層ガス化及び熔融燃焼装置の配置図。
【図１２】廃熱ボイラ及び反応塔と組み合わせて使用される本発明の実施例の流動層ガス化及び熔融燃焼装置の配置図。
【図１３】本発明のガス化コジェネレーション型の実施例の流動層ガス化及び熔融燃焼装置の配置図。
【図１４】本発明の加圧ガス化複合発電型の実施例の流動層ガス化及び熔融燃焼方法の工程を示すフロー図。
【符号の説明】
１；ガス化装置、２；流動層炉、３；炉底周辺部、４；炉底中央部、５；不燃物排出口、６；傾斜壁、７；中央流動化ガス、７’；中間流動化ガス、８；周辺流動化ガス、９；移動層、９’；中間層、１０；流動層、１１；ガス化原料（可燃物）、１２；ダブルダンパー、１３；圧縮フィーダ、１４；給塵フィーダ、１５；ルーツブロア、１６；円錐形シュート、１７；定量排出器、１８、２０；スイング弁、１９、１９’；スイングカット弁、２２；排出弁、２３；トロンメル付き連続排出器、２４；砂循環エレベータ、２５；分級器、２７、２８；不燃物、２９；生成ガス、３１、３１’；廃熱ボイラ、３２；サイクロン分離機、３６；廃水処理器、３７；未反応チャー、３８；固形分、４１；熔融燃焼炉、４３、４３’；集塵器、４４；熔融灰、５４；誘引通風機、５５；排気塔、１０２；フリーボード、１０４；可燃物供給口、１０６；ガス分散機構、１０８；ガス出口、１１４；チャー・タール、１３４；助燃バーナ、１４０；一次燃焼室、１４２；可燃ガス入口、１５０；二次燃焼室、１６２；輻射板、１７６；スラグ、１７８；水室、１８３；エコノマイザ、１８５；空気ジャケット、１８６、１８８；空気予熱器、１９４、５１０；処理器、２８０；ガス冷却器、３１０；反応塔、３２０；スーパーヒータ加熱燃焼器、４２０；ガスタービン、Ａ；空気、Ｃ；圧縮機、ＣＣ；燃焼器、ＥＣｏ；エコノマイザ、Ｆ；補助燃料、Ｇ；ガス化ゾーン、Ｎ；中和剤、Ｓ；酸化ゾーン、ＳＨ；スーパーヒータ、ＳＴ；蒸気タービン、Ｔ；タービン、Ｗ；水。[0001]
[Industrial applications]
The present invention relates to a method and an apparatus for gasifying combustibles in a fluidized-bed furnace and burning the generated combustible gas and fine particles at a high temperature in a melting and burning furnace to melt ash.
[0002]
[Prior art]
2. Description of the Related Art In recent years, it has been desired to incinerate a large amount of municipal waste and waste plastics and other wastes to reduce the amount thereof, and to effectively utilize the heat of incineration. Since waste incineration ash usually contains harmful heavy metals, it is necessary to take measures such as solidifying heavy metal components in order to treat incineration ash by landfill. In order to cope with these problems, a method and apparatus for burning solids have been proposed in Japanese Patent Publication No. 62-35004. In the combustion method disclosed in this publication, a solid material is pyrolyzed in a fluidized bed pyrolysis furnace, and pyrolysis products, that is, combustible gas and particles are introduced into a cyclone combustion furnace. In the cyclone combustion furnace, flammable components are burned with high load by pressurized air, and ash collides with the wall surface due to the swirling flow and melts and flows down the wall surface. .
[0003]
In the method disclosed in Japanese Patent Publication No. 62-35004, a high gasification efficiency is obtained because the entire fluidized bed is in an active fluidized state and a large amount of unreacted combustibles are scattered out of the furnace along with the generated gas. There were disadvantages such as not being able to. Conventionally, as a gasification raw material that can be used in a fluidized bed furnace, coal or the like has been powdered coal having a particle size of 0.5 to 3 mm, and waste has been crushed to several tens of mm. If it is larger than this, fluidization will be hindered, and if it is smaller than this, it will not be completely gasified and will fly out of the furnace as unreacted combustibles along with the generated gas. Therefore, in conventional fluidized bed furnaces, it is indispensable to crush and size using a pulverizer or the like in advance as a pretreatment before charging the gasification raw material into the furnace, and do not fall within a predetermined particle size range. Gasification feedstock was not available and yields had to be sacrificed to some extent.
[0004]
In order to solve the above-mentioned problems, a fluidized-bed gasification method and a fluidized-bed gasification furnace disclosed in Japanese Patent Application Laid-Open No. 2-147692 have been proposed. In the fluidized-bed gasification method disclosed in this publication, the horizontal cross section of the furnace is rectangular, and the mass velocity of the fluidizing gas ejected upward from the center of the furnace bottom into the furnace is increased from two side edges of the furnace bottom. The mass velocity of the fluidizing gas to be supplied is made smaller, the upward flow of the fluidizing gas is diverted to the central part of the furnace above the bottom edge of the furnace, and a moving bed is formed in the central part of the furnace where the fluidized medium sinks, Fluidized beds in which the fluidized medium is actively fluidized are formed on both side edges of the furnace, and combustibles are supplied to the moving bed. The fluidizing gas is a mixture of air and steam or a mixture of oxygen and steam, and the fluidizing medium is quartz sand.
[0005]
However, the method disclosed in Japanese Patent Application Laid-Open No. 2-147692 has the following disadvantages. That is, (1) In the entire moving bed and the fluidized bed, a gasification endothermic reaction and a combustion reaction occur simultaneously, and volatile components that are easily gasified are gasified and burned at the same time, and fixed carbon (char) and tar components that are difficult to gasify And the like are scattered outside the furnace as unreacted substances with the produced gas, and high gasification efficiency cannot be obtained. (2) When the produced gas is burned and used in a combined steam and gas turbine power plant, it is necessary to use a pressurized fluidized bed furnace. Have difficulty. The preferred gasifier internal pressure is determined by the product gas application. When used as a general combustion gas, the pressure may be about several thousand mmAq. ² The above is necessary, and when used as a fuel for high-efficiency gasification combined cycle power generation, more than ten ² The above is appropriate.
[0006]
Regarding waste treatment such as municipal solid waste, reduction of the amount of combustible waste by combustion still plays an important role, and accompanying this, in recent years, measures against dioxins, detoxification of dust, and improvement of energy recovery efficiency For example, the need for environmentally friendly waste treatment technology is increasing. The amount of incineration of municipal solid waste in Japan is about 100,000 tons / day, and the total energy of municipal solid waste corresponds to about 4% of the power consumption of Japan. At present, the energy utilization rate of municipal solid waste is only about 10%. However, if the utilization rate can be increased, the consumption of fossil fuel will be reduced accordingly, which can contribute to the prevention of global warming.
[0007]
However, current incineration systems include the following problems. That is, (1) there is a problem of corrosion due to HCl, and the power generation efficiency cannot be increased. {Circle around (2)} Pollution prevention equipment for HCl, NOx, SOx, mercury, dioxin and the like has become complicated, and costs and space have increased. (3) Installation of melting facilities for incinerated ash is increasing due to the strengthening of laws and regulations, land shortage at the final disposal site, etc. Therefore, construction of separate facilities is required, and large amounts of electricity etc. are consumed. I have. (4) Expensive equipment is required to remove dioxin. (5) It is difficult to recover valuable metals.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems of the prior art, and to efficiently generate combustible gas containing a large amount of combustibles from municipal waste, waste such as waste plastic, and combustibles such as coal. Another object of the present invention is to provide a processing method and a gasification and melting apparatus capable of melting combustion ash by the self-calorific value of the generated combustible gas. In the present invention, the generated gas supplied to the melting furnace has a sufficient amount of heat to generate a high temperature of 1300 ° C. or more by its own heat, and is made to be a homogeneous gas containing char and tar. The incombustibles are discharged from the gasifier without any trouble. Another object of the present invention is to provide a gasification method and apparatus capable of extracting and recovering valuable metals in waste from a fluidized bed furnace in a reducing atmosphere without oxidizing the valuable metals. Further objects of the present invention will become apparent in the description of embodiments with reference to the drawings.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the gasification and melting device of the present invention is a device that melts ash after gasification of waste, and in a device that melts ash, a fluidized medium composed of a fluidized medium rising in a furnace and a fluidized medium settling. Equipped with a fluidized bed furnace having a circulating flow, the waste is gasified to generate gas and char, the temperature of the fluidized bed in which the fluidized medium rises is maintained at 450 to 650 ° C, and the suppressed combustion reaction continues. And a melting furnace for supplying the gas and the char from the fluidized bed furnace to melt ash.
The gasification and melting device of the present invention is a device that melts ash after gasifying waste, supplies air as a fluidizing gas into the furnace, and has a relatively large mass velocity of the fluidizing gas and the mass velocity. A fluidized bed furnace having a circulating flow of fluidized medium formed by a relatively small fluidizing gas, wherein the waste is gasified to produce gas and char and fluidized by the relatively high mass velocity fluidizing gas. The temperature of the fluidized bed was maintained at 450 ° C. to 650 ° C., and the suppressed combustion reaction was continued, and a melting furnace was provided for supplying the gas and the char from the furnace and melting the ash. It is characterized by the following.
The fluid medium is raised by a fluidizing gas having a relatively high mass velocity.
The circulating flow of the fluidized medium comprising the rising fluidized medium and the settling fluidized medium is formed by a fluidized gas having a relatively large mass velocity and a fluidized gas having a relatively small mass velocity.
Air is supplied as fluidizing gas into the fluidized bed furnace.
The gasification and melting device of the present invention is a device that melts ash after gasifying waste, and includes a fluidized bed furnace having a circulating flow of a fluidized medium composed of a fluidized medium rising and a fluidized medium settled in the furnace. Gasification of the waste to produce gas and char, the temperature of the fluidized bed in which the fluidized medium rises is maintained at 450 ° C. to 650 ° C., and a part of the generated char is fluidized bed in which the fluidized medium rises And a melting furnace for melting the ash by supplying the gas and the char from the fluidized bed furnace.
The gasification and melting device of the present invention is a device that melts ash after gasifying waste, supplies air as a fluidizing gas into the furnace, and has a relatively large mass velocity of the fluidizing gas and the mass velocity. A fluidized bed furnace having a circulating flow of fluidized medium formed by a relatively small fluidizing gas, wherein the waste is gasified to produce gas and char and fluidized by the relatively high mass velocity fluidizing gas. The temperature of the fluidized bed is maintained at 450 ° C. to 650 ° C., and a part of the generated char is burned in a fluidized bed fluidized by a fluidizing gas having a relatively high mass velocity. And a melting furnace for supplying the char and melting the ash.
The fluid medium is raised by a fluidizing gas having a relatively high mass velocity.
The circulating flow of the fluidized medium comprising the rising fluidized medium and the settling fluidized medium is formed by a fluidized gas having a relatively large mass velocity and a fluidized gas having a relatively small mass velocity.
Air is supplied as fluidizing gas into the fluidized bed furnace.
The waste is municipal waste or waste plastic.
The melting furnace was provided with a nozzle for supplying oxygen or a mixed gas of oxygen and air.
The gas and char supplied from the fluidized bed furnace are burned at 1300 ° C. or more in the melting furnace.
The fluidized bed furnace was at a low air ratio.
The air amount of the entire fluidized gas supplied into the fluidized bed furnace is set to 30% or less of the theoretical combustion air amount.
A plurality of fluidizing gas supply means for supplying a fluidizing gas into the fluidized bed furnace are provided.
The method for treating waste according to the present invention is a method for melting ash after gasifying waste, in a fluidized-bed furnace having a circulating flow of a fluidized medium consisting of a fluidized medium rising in a furnace and a fluidized medium settling. The waste is supplied and gasified to generate gas and char, and the temperature of the fluidized bed where the fluidized medium rises is maintained at 450 ° C. to 650 ° C. so that the suppressed combustion reaction is continued, The gas and the char are supplied from a bed furnace to a melting furnace to melt ash.
The waste disposal method of the present invention is a method of melting ash after gasifying waste, in which air is supplied as a fluidizing gas into the furnace, and the fluidizing gas having a relatively large mass velocity and the mass velocity are supplied. The waste is supplied to a fluidized bed furnace having a circulating flow of a fluidized medium formed by a relatively small fluidizing gas, gasified to produce gas and char, and fluidized by a fluidizing gas having a relatively high mass velocity. Maintaining the temperature of the fluidized bed at 450 ° C. to 650 ° C. so that the suppressed combustion reaction is continued, and supplying the gas and the char from the fluidized bed furnace to the melting furnace to melt the ash. It is characterized by.
The fluid medium is raised by a fluidizing gas having a relatively high mass velocity.
The circulating flow of the fluidized medium comprising the rising fluidized medium and the settling fluidized medium is formed by a fluidized gas having a relatively large mass velocity and a fluidized gas having a relatively small mass velocity.
The method for treating waste according to the present invention is a method for melting ash after gasifying waste, in a fluidized-bed furnace having a circulating flow of a fluidized medium consisting of a fluidized medium rising in a furnace and a fluidized medium settling. The waste is supplied, gasified to generate gas and char, the temperature of the fluidized bed where the fluidized medium rises is maintained at 450 ° C. to 650 ° C., and a part of the generated char is fluidized with the fluidized medium rising. The gas and the char are supplied from a fluidized bed furnace to a melting furnace to melt ash.
The waste disposal method of the present invention is a method of melting ash after gasifying waste, in which air is supplied as a fluidizing gas into the furnace, and the fluidizing gas having a relatively large mass velocity and the mass velocity are supplied. The waste is supplied to a fluidized bed furnace having a circulating flow of a fluidized medium formed by a relatively small fluidizing gas, gasified to produce gas and char, and fluidized by a fluidizing gas having a relatively high mass velocity. The temperature of the fluidized bed to be maintained is maintained at 450 ° C. to 650 ° C., and a part of the produced char is burned in a fluidized bed fluidized by a fluidizing gas having a relatively high mass velocity. The gas and the char are supplied to a melting furnace to melt ash.
The fluid medium is raised by a fluidizing gas having a relatively high mass velocity.
The circulating flow of the fluidized medium comprising the rising fluidized medium and the settling fluidized medium is formed by a fluidized gas having a relatively large mass velocity and a fluidized gas having a relatively small mass velocity.
The waste is municipal waste or waste plastic.
Oxygen or a mixed gas of oxygen and air is supplied to the melting furnace.
The gas and char supplied from the fluidized bed furnace are burned at 1300 ° C. or more in the melting furnace.
The fluidized bed furnace was at a low air ratio.
The air amount of the entire fluidized gas supplied into the fluidized bed furnace is set to 30% or less of the theoretical combustion air amount.
A fluidized gas is supplied into the fluidized bed furnace by a plurality of fluidized gas supply means.
The waste gasifier of the present invention is a gasifier for gasifying waste, wherein the gasifier is a fluidized bed furnace having a circular horizontal cross section, and the fluidized bed furnace is a central part of the furnace. And a peripheral fluidizing gas supply means for forming a fluidized bed in which the fluidized medium rises at the periphery of the furnace, wherein the fluidized medium is provided with a fluidized bed. And forming a circulating flow through the fluidized bed, supplying the waste to the fluidized bed furnace to gasify, and the fluidized bed furnace is configured to discharge the incombustibles contained in the waste and the incombustibles discharging the fluidized medium. A discharge port is provided, and a valve is provided for sealing the internal pressure of the fluidized-bed furnace when discharging the incombustibles contained in the waste and the fluid medium, and the discharged incombustibles and the fluid medium are separated and separated. The fluidized medium may be returned to the fluidized bed furnace.
[0010]
The waste gasification method of the present invention is a method of gasifying waste in a fluidized bed furnace, in which the horizontal section of the fluidized bed furnace is circular, and a fluidized medium settles in the fluidized bed furnace at the center. Forming a moving bed and a fluidized bed in which a fluidized medium rises at the periphery of the furnace, forming the fluidized medium through the moving bed and the fluidized bed to form a circulating flow of the fluidized medium, and transferring the waste to the fluidized bed furnace. The fluidized medium is discharged from the bottom of the fluidized bed furnace while sealing the internal pressure, and the incombustible material and the fluidized medium contained in the waste are discharged. Is returned to the fluidized bed furnace.
[0011]
In the present invention, combustibles are gasified into combustible gas in a fluidized bed furnace. In the method of the present invention, the horizontal section of the fluidized-bed furnace is made substantially circular, and the fluidizing gas supplied to the fluidized-bed furnace is supplied from the vicinity of the central part of the furnace bottom to the central fluidizing gas and the periphery of the furnace bottom. And the mass velocity of the central fluidizing gas is made smaller than the mass velocity of the peripheral fluidizing gas, and the upward flow of the fluidizing gas above the peripheral part in the furnace Is turned by the inclined wall toward the center of the furnace, thereby forming a moving bed in which the flowing medium (typically using silica sand) settles and diffuses in the center of the furnace and flows around the furnace. A fluidized bed in which the medium is actively fluidized is formed, and the flammable gas supplied into the furnace is circulated with the flammable gas while circulating with the fluidized medium from the bottom of the moving bed to the fluidized bed and from the top of the fluidized bed to the moving bed. And the oxygen content of the central fluidizing gas is Or less oxygen content of sides fluidizing gas, the temperature of the fluidized bed is maintained at 450 to 650 ° C..
[0012]
In the present invention, the central fluidizing gas is one of three gases: steam, a mixture of steam and air, and air. In addition, the peripheral fluidizing gas is one of three types of gas: oxygen, a mixed gas of oxygen and air, and air. Therefore, there are nine combinations of central fluidizing gas and peripheral fluidizing gas, as shown in Table 1. Which combination is selected depends on whether importance is placed on gasification efficiency or economy.
[0013]
[Table 1]

The combination with the highest gasification efficiency is No. Although the combination is 1, the cost is high because of the large amount of oxygen consumption. The order of decreasing oxygen consumption and then steam consumption decreases gasification efficiency, but also reduces cost. The oxygen used in the present invention may be of high purity or of low purity obtained using an oxygen-enriched membrane. No. The combination of air and air of No. 9 is known as combustion air of a conventional incinerator. However, in the present invention in which the horizontal section of the fluidized bed furnace is circular, the downward projection of the inclined wall provided above the peripheral portion in the furnace is performed. Since the area is larger than the downward projected area of the inclined wall when the horizontal cross section of the fluidized bed furnace is rectangular, the flow rate of the peripheral fluidizing gas can be increased, and therefore the oxygen supply amount can be increased, so that the gasification efficiency is improved. Can be done.
[0014]
Preferably, the method of the present invention further includes an intermediate fluidizing gas in which the fluidizing gas is supplied into the furnace from a middle portion of the bottom between the central portion and the peripheral portion of the bottom. The mass velocity of the intermediate fluidization gas is between the mass velocity of the central fluidization gas and that of the peripheral fluidization gas. The intermediate fluidizing gas is one of two types of gas: a mixture of steam and air, and air. Therefore, the number of combinations of the central fluidizing gas, the intermediate fluidizing gas, and the peripheral fluidizing gas is 18, and it is advantageous that the oxygen content increases in order from the central portion of the furnace to the peripheral portion, Preferred combinations are shown in Table 15 below.
[0015]
[Table 2]

Which one of the combinations in Table 2 is selected depends on whether importance is placed on gasification efficiency or economic efficiency. Of the combinations in Table 2, the combination with the highest gasification efficiency is No. Although the combination is 1, the cost is high because of the large amount of oxygen consumption. The order of decreasing oxygen consumption and then steam consumption decreases gasification efficiency, but also reduces cost. The oxygen used in Tables 1 and 2 may be of high purity or of low purity obtained using an oxygen-enriched membrane.
[0016]
When the fluidized bed furnace is large, the intermediate fluidizing gas is preferably a plurality of fluidizing gases supplied from a plurality of concentric intermediate portions provided between the central portion of the furnace bottom and the peripheral portion of the furnace bottom. . In this case, it is preferable that the oxygen concentration of the fluidizing gas be the lowest in the central part of the furnace and be higher as approaching the peripheral part.
[0017]
In the method of the present invention, preferably, the fluidizing gas supplied to the fluidized bed furnace contains an air amount of 30% or less of the theoretical combustion air amount required for combustion of combustibles. Incombustibles are taken out from the vicinity of the bottom of the fluidized bed furnace, classified, and the obtained sand is returned into the fluidized bed furnace. The combustible gas and fine particles generated in the fluidized bed furnace are burned at a high temperature of 1300 ° C. or more in the melting and burning furnace, and the ash is melted. The gas turbine is driven by the exhaust gas from the melting and burning furnace. The pressure in the fluidized bed furnace is maintained at or below atmospheric pressure or above atmospheric pressure depending on the application. Combustibles are waste, coal, and others.
[0018]
The present invention also provides an apparatus in which combustibles are gasified in a fluidized bed furnace. In the apparatus of the present invention, the fluidized bed furnace has a side wall having a substantially circular horizontal cross section, a fluidizing gas dispersion mechanism arranged at the bottom of the furnace, an incombustible material outlet arranged at an outer periphery of the fluidizing gas dispersion mechanism, and fluidization. Central supply means for supplying fluidized gas to flow vertically upward into the furnace from near the center of the gas dispersion mechanism, and flowing fluidized gas vertically upward into the furnace from the periphery of the fluidized gas dispersion mechanism. Peripheral supply means for supplying a fluidized gas flowing vertically upward from the peripheral supply means to the furnace central portion, and a free board disposed above the inclined wall, the central supply means comprising: The fluidizing gas having a relatively low mass velocity and a relatively low oxygen concentration is supplied, and the peripheral supply means supplies the fluidizing gas having a relatively high mass velocity and a relatively high oxygen concentration.
[0019]
In the apparatus of the present invention, there is provided an intermediate supply means for supplying the fluidized gas vertically upward into the furnace from the ring-shaped intermediate portion between the central portion and the peripheral portion of the fluidized gas dispersion mechanism. The intermediate supply means has a mass velocity intermediate between the mass velocities of the fluidizing gas supplied from the central supply means and the peripheral supply means, and an oxygen concentration intermediate between the oxygen concentrations of the fluidizing gas supplied from the central supply means and the peripheral supply means. Supply a concentration of fluidizing gas. The peripheral supply means can be formed by a ring-shaped supply box. The combustible material inlet is disposed above the fluidized bed furnace, the combustible material inlet drops the combustible material above the central supply means, and the fluidized gas dispersion mechanism is formed to be lower at the peripheral portion than at the central portion. it can.
[0020]
The incombustible material outlet may have a ring portion disposed on the outer periphery of the dispersing mechanism and a conical portion that decreases downward from the ring-shaped portion. The noncombustible material outlet may include a fixed amount discharger, a first seal swing valve, a swing cut valve, and a second seal swing valve arranged in series.
[0021]
The apparatus of the present invention may include a melting and burning furnace that burns combustible gas and fine particles generated in a fluidized bed furnace at a high temperature to melt ash. The melting and burning furnace has a cylindrical primary combustion chamber having a substantially vertical axis, and a combustible gas inlet for supplying the combustible gas and fine particles generated in the fluidized bed furnace to the cylindrical primary combustion chamber in a swirling manner around the axis. A secondary combustion chamber communicated with the cylindrical primary combustion chamber; and a discharge port provided at a lower portion of the secondary combustion chamber and capable of discharging molten ash. Exhaust gas from the secondary combustion chamber of the melting and burning furnace is introduced into a waste heat boiler and an air preheater, and waste heat is recovered. The gas turbine can be driven by the exhaust gas from the secondary combustion chamber of the melting combustion furnace. The exhaust gas can be released to the atmosphere after being introduced into the dust collector and the dust is removed. Exhaust gas from the secondary combustion chamber of the melting and burning furnace is introduced into a waste heat boiler and an air preheater, and waste heat can be recovered. The gas turbine can be driven by the exhaust gas from the secondary combustion chamber of the melting combustion furnace. The exhaust gas is introduced into the dust collector, and is discharged into the atmosphere after dust is removed.
[0022]
[Action]
In the gasifier of the present invention, heat is diffused by the circulating flow of the fluidized-bed furnace, so that the load can be increased and the furnace can be downsized.
In the present invention, since the fluidized-bed furnace can maintain combustion with a small amount of air, the fluidized-bed furnace has a low air ratio and low temperature (450 to 650 ° C.), minimizes heat generation, and performs gradual combustion. As a result, a homogeneous product gas containing a large amount of combustibles can be obtained, and most of the combustibles of gas, tar, and char can be used in the next melting and burning furnace.
In the present invention, large incombustibles can be easily discharged by the circulating flow of the fluidized bed furnace. In addition, iron and aluminum in incombustibles can be used as unoxidized valuables.
In the method or apparatus of the present invention, the horizontal cross section of the fluidized bed furnace is made substantially circular, so that the furnace has a pressure-resistant structure, the fluidized bed furnace is pressurized above atmospheric pressure, and the combustible material supplied into the furnace is It is easy to make the pressure of the combustible gas generated from high pressure high. High-pressure flammable gas can be used as fuel for gas turbines and boiler / gas turbine combined plants that can operate with high efficiency, and therefore, by using flammable gas in such plants, energy from combustibles can be reduced. Recovery efficiency can be improved. In the method or the apparatus of the present invention, when mainly treating refuse, in order to prevent odor and harmful combustion gas from leaking from the fluidized bed furnace, it is preferable that the furnace pressure is equal to or lower than the atmospheric pressure. Since the horizontal cross section of the fluidized bed furnace is circular, the furnace wall can easily withstand external pressure.
[0023]
In the present invention, the mass velocity of the central fluidizing gas supplied to the fluidized bed furnace is made smaller than the mass velocity of the peripheral fluidizing gas, and the upward flow of the fluidizing gas above the peripheral part in the furnace is changed to the central part of the furnace. As a result, a moving bed in which the flowing medium is settled and diffused is formed in the center of the furnace, and a fluidized bed in which the flowing medium is actively fluidized is formed in the periphery of the furnace. The combustibles supplied into the furnace are gasified into combustible gas while circulating with the fluidized medium from the lower part of the moving bed to the fluidized bed and from the top of the fluidized bed to the moving bed. The combustibles are first gasified in the descending moving bed in the center of the furnace, mainly by the volatiles due to the heat of the flowing medium (typically using silica sand). And, since the oxygen content of the central fluidizing gas forming the moving bed is small, the combustible gas generated in the moving bed is hardly burned and rises to the freeboard together with the central fluidizing gas, and the calorific value is high. It becomes a high quality product gas.
[0024]
The combustibles, which have lost volatiles and are heated in the moving bed, that is, fixed carbon (char) and tar, are then circulated into the fluidized bed, and peripheral fluidization with a relatively high oxygen content in the fluidized bed. The gas is burned in contact with the gas, converted into combustion gas and ash, and generates combustion heat that maintains the inside of the furnace at 450 to 650 ° C. The fluidized medium is heated by the heat of combustion, and the heated fluidized medium is turned to the central part of the furnace above the peripheral part of the furnace and descends in the moving bed, thereby lowering the temperature in the moving bed to a temperature required for gasification of volatile matter. To maintain. Since the center of the furnace where the combustibles are charged is in a low oxygen state, a product gas having a high combustible content can be generated. In addition, the metals in the combustibles can be recovered from the incombustibles outlet as unoxidized valuables.
[0025]
In the present invention, when the gas, ash, and other fine particles generated in the fluidized bed furnace are burned in the melting and burning furnace, the generated gas contains a high flammable content, so that no heating fuel is required, and the inside of the melting furnace is not required. Can be raised to a high temperature of 1300 ° C. or more, and the ash can be sufficiently melted in the melting furnace. The molten ash can be easily taken out of the melting furnace and solidified by a known method such as water cooling. Thus, the ash volume is significantly reduced and the harmful metals in the ash are solidified, leaving the ash in a landfillable form. Other effects of the present invention will be apparent from the claims and the description of the embodiments with reference to the drawings.
[0026]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto, but is defined by the claims. In addition, in FIGS. 1 to 14, members denoted by the same reference numerals are the same members or corresponding members, and redundant description is omitted in the description of each drawing.
[0027]
FIG. 1 is a schematic longitudinal sectional view of a main part of a gasifier of a first embodiment for carrying out the gasification method of the present invention, and FIG. 2 is a schematic horizontal sectional view of the gasifier of FIG. is there. In the gasifier shown in FIG. 1, the fluidizing gas supplied into the fluidized bed furnace 2 through the fluidizing gas dispersing mechanism 106 arranged at the furnace bottom flows upward from the vicinity of the center 4 of the furnace bottom into the furnace. And a peripheral fluidizing gas 8 supplied as an upward flow from the furnace bottom peripheral portion 3 into the furnace.
[0028]
As shown in Table 1, the central fluidizing gas 7 is one of three types of gas: steam, a mixed gas of steam and air, and air, and the peripheral fluidizing gas 8 is oxygen, oxygen and A mixture of air and one of three types of air. The oxygen content of the central fluidizing gas is less than or equal to the oxygen content of the peripheral fluidizing gas. The air amount of the entire fluidizing gas is set to 30% or less of the theoretical combustion air amount necessary for combustion of the combustibles 11, and the inside of the furnace is set to a reducing atmosphere.
[0029]
The mass velocity of the central fluidizing gas 7 is less than the mass velocity of the peripheral fluidizing gas 8 and the upward flow of the fluidizing gas above the perimeter in the furnace is diverted by the deflector 6 to the central part of the furnace. . As a result, a moving bed 9 in which the fluidized medium (usually silica sand) is settled and diffused is formed in the center of the furnace, and a fluidized bed 10 in which the fluidized medium is actively fluidized is formed in the periphery of the furnace. Is done. The fluidized medium rises in the fluidized bed 10 around the furnace, as shown by the arrow 118, is then turned by the deflector 6, flows above the moving bed 9, descends in the moving bed 9, and then moves down the arrow. As shown by 112, it moves along the gas dispersion mechanism 106 and flows below the fluidized bed 10 to circulate through the fluidized bed 10 and the moving bed 9 as shown by arrows 118 and 112.
[0030]
The combustible material 11 supplied from the combustible material supply port 104 to the upper part of the moving bed 9 is heated by the heat of the flowing medium while descending in the moving bed 9 together with the flowing medium, and mainly the volatile matter is gasified. . Since there is no or little oxygen in the moving bed 9, the generated gas composed of the gasified volatiles is not burned and passes through the moving bed 9 as indicated by an arrow 116. Therefore, the moving bed 9 forms the gasification zone G. The product gas that has moved to the free board 102 rises as indicated by an arrow 120 and is discharged from the gas outlet 108 as the product gas 29.
[0031]
Mainly char (fixed carbon content) and tar 114 which are not gasified in the moving bed 9 move from the lower part of the moving bed 9 to the lower part of the fluidized bed 10 in the peripheral part of the furnace together with the fluidized medium as shown by an arrow 112, It is burned by the peripheral fluidizing gas 8 having a relatively high oxygen content and is partially oxidized. The fluidized bed 10 forms an oxidation zone S for combustibles. In the fluidized bed 10, the fluidized medium is heated by combustion heat in the fluidized bed to a high temperature. The high temperature fluid medium is inverted by the inclined wall 6 as shown by an arrow 118, moves to the moving bed 9, and becomes a heat source for gasification again. The temperature of the fluidized bed 10 is maintained at 450 to 650 ° C. so that the suppressed combustion reaction continues.
[0032]
According to the gasification furnace 1 shown in FIGS. 1 and 2, the gasification zone G and the oxidation zone S are formed in the fluidized bed furnace 2, and the fluidized medium serves as a heat transfer medium in both zones. , A high-quality combustible gas having a high calorific value is generated, and in the oxidation zone S, char and tar 114 that are difficult to gasify can be efficiently burned. Therefore, the gasification efficiency of combustibles can be improved, and high-quality combustible gas can be generated.
[0033]
In the horizontal section of the fluidized bed furnace 2 shown in FIG. 2, the moving bed 9 forming the gasification zone G is circular at the center of the furnace, and the fluidized bed 10 forming the oxidation zone S is formed around the moving bed 9. It is formed in a ring shape. A ring-shaped incombustible substance discharge port 5 is arranged on the outer periphery of the fluidized bed 10. By making the gasification furnace 1 cylindrical, a high furnace pressure can be easily supported. A pressure vessel (not shown) can be separately provided outside the gasification furnace, instead of the structure in which the gasification furnace itself receives the internal pressure of the gasification furnace.
[0034]
FIG. 3 is a schematic vertical sectional view of a main part of a gasifier of a second embodiment for carrying out the gasification method of the present invention, and FIG. 4 is a schematic horizontal sectional view of the gasifier of FIG. is there. In the gasifier of the second embodiment shown in FIG. 3, the fluidizing gas includes a central fluidizing gas 7 and a peripheral fluidizing gas 8, and a middle portion of the furnace bottom between the central portion of the furnace bottom and the peripheral portion of the furnace bottom. And an intermediate fluidizing gas 7 'supplied into the furnace from the furnace. The mass velocity of the intermediate fluidizing gas 7 ′ is chosen between the mass velocity of the central fluidizing gas 7 and the peripheral fluidizing gas 8. The intermediate fluidizing gas is any one of three types of gas: steam, a mixture of steam and air, or air.
[0035]
In the gasifier of FIG. 3, as in the case of the gasifier of FIG. 1, the central fluidizing gas 7 is one of three gases: steam, a mixture of steam and air, and air. The peripheral fluidizing gas 8 is one of three gases: oxygen, a mixed gas of oxygen and air, and air. The oxygen content of the intermediate fluidizing gas is selected between the oxygen content of the central fluidizing gas and the oxygen content of the peripheral fluidizing gas. Therefore, the preferred combinations of the fluidizing gases are 15 in Table 2. In each combination, it is important that the oxygen supply increases as it extends from the center to the periphery of the fluidized bed furnace. The air amount of the entire fluidizing gas is set to 30% or less of the theoretical combustion air amount necessary for combustion of the combustibles 11, and the inside of the furnace is set to a reducing atmosphere.
[0036]
As in the case of the gasifier of FIG. 1, in the gasifier of FIG. 3, a moving bed 9 in which a flowing medium settles is formed in the center of the furnace, and a moving bed 10 in which the flowing medium rises in the periphery of the furnace. Is formed. A fluidized medium circulates through the moving and fluidized beds as indicated by arrows 112 and 118. Between the moving bed 9 and the fluidized bed 10, an intermediate layer 9 'is formed in which the fluidized medium mainly diffuses in the lateral direction. The moving bed 9 and the intermediate layer 9 ′ form a gasification zone G, and the fluidized bed 10 forms an oxidation zone S.
[0037]
The combustible material 11 introduced into the upper part of the moving bed 9 is heated while descending in the moving bed 9 together with the fluidized medium, and the volatile matter is gasified. The char and tar and some volatiles that have not been gasified in the moving bed 9 move to the intermediate layer 9 ′ and the fluidized bed 10 together with the fluidized medium, and are partially gasified and partially burned. Mainly char and tar not gasified in the intermediate layer 9 ′ move into the fluidized bed 10 around the furnace together with the fluidized medium, and are burned in the peripheral fluidized gas 8 having a relatively high oxygen content. The fluidized medium is heated in the fluidized bed 10 and circulates to the moving bed 9 to heat the combustibles in the moving bed 9. Regarding the oxygen concentration of the intermediate layer, depending on the type of combustibles (whether there is a lot of volatile matter, or a lot of char and tar), etc., lower the oxygen concentration and mainly gasify, or increase the oxygen concentration. Whether oxidative combustion is the main component is selected.
[0038]
In the horizontal section of the fluidized-bed furnace shown in FIG. 4, the moving bed 9 forming the gasification zone is circular at the center of the furnace, and has an intermediate zone 9 formed by the intermediate fluidized gas 7 'along the outer periphery thereof. And the fluidized bed 10 forming the oxidation zone is formed in a ring around the intermediate zone 9 '. A ring-shaped incombustible substance discharge port 5 is arranged on the outer periphery of the fluidized bed 10. By making the gasification furnace 1 cylindrical, a high furnace pressure can be easily supported. The furnace pressure can be received by the gasifier itself or by providing a separate pressure vessel outside the gasifier.
[0039]
FIG. 5 is a schematic vertical sectional view of a gasifier according to a third embodiment of the present invention. In the gasifier 1 of FIG. 5, the gasification raw material 11 made of combustibles such as refuse is supplied to the fluidized bed furnace 2 of the gasifier 1 by the double damper 12, the compression feeder 13, and the dust feeder 14. . The compression feeder 13 compresses the gasified raw material into a plug shape, thereby sealing the furnace pressure. The dust compressed in a plug shape is separated by a loosening device (not shown) and sent to the furnace by a dust feeder 14.
[0040]
In the gasifier of FIG. 5, the central fluidizing gas 7 and the peripheral fluidizing gas 8 are supplied in the same manner as in the embodiment of FIG. 1, and therefore are reduced to the fluidized bed furnace 2 in the same manner as in the embodiment of FIG. An atmosphere gasification zone and an oxidation zone are formed. The fluidized medium serves as a heat transfer medium in both zones, and in the gasification zone, high-quality combustible gas with a high calorific value is generated. In the oxidation zone, char and tar 114, which are difficult to gasify, are efficiently burned, resulting in high gasification. Efficiency and high quality combustible gas can be obtained. In the embodiment of FIG. 5, a roots blower 15 communicating with the double damper 12 and the free board 102 of the gasification furnace 1 is provided, and when the compression of dust is insufficient, the dust leaks from the furnace through the compression feeder to the double damper 12. Return the gas into the furnace. Preferably, the roots blower 15 sucks an appropriate amount of air and gas from the double damper 12 and returns it into the furnace so that the upper part of the double damper 12 is at atmospheric pressure.
[0041]
In the gasifier of FIG. 5, in order to discharge incombustibles from the fluidized-bed furnace 2, the incombustibles discharge port 5, the conical chute 16, the fixed-quantity discharger 17, the first swing valve for sealing 18, the swing cut valve 19, and the seal are used. The second swing valve for use 20 and the discharger with trommel 23 are arranged in order, and are operated as follows.
[0042]
(1) When the first swing valve 18 for sealing is opened, the second swing valve 20 is closed, and the furnace pressure is sealed by the second swing valve 20, the constant-rate discharger 17 is operated and the fluid medium is discharged. Is discharged from the conical chute 16 to the swing cut valve 19. (2) When the swing cut valve 19 receives a predetermined amount of incombustible material, the fixed amount discharger 17 is turned off, the first swing valve 18 is closed, and the furnace pressure is sealed by the first swing valve 18. Then, the discharge valve 22 is opened, and the inside of the swing cut valve 19 is returned to the atmospheric pressure. Next, the second swing valve 20 is completely opened, and the swing cut valve 19 is opened, so that incombustibles are discharged to the continuous discharger 23 with trommel. (3) After the second swing valve 20 is completely closed, the equalizing valve 21 is opened, and the inside of the first swing valve 18 and the inside of the conical chute 16 are equalized. The valve 18 is opened and returns to the first step (1). These steps (1) to (3) are automatically and repeatedly operated.
[0043]
The continuous discharger 23 with trommel is operated continuously, discharges large incombustibles 27 out of the system by trommel, transports sand and small incombustibles by the sand circulation elevator 24, and removes fine incombustibles 28 by the classifier 25. After that, the sand is returned to the gasification furnace 1 via the lock hopper 26. In such an incombustible discharge mechanism, since the two swing valves have only a pressure sealing function without receiving incombustibles, it is necessary to avoid the incombustibles from being caught in the seal portions of the first and second swing valves 18 and 20. Can be. When the furnace pressure may be slightly negative, the sealing function is unnecessary.
[0044]
FIG. 6 is a schematic vertical sectional view of a gasifier according to a fourth embodiment of the present invention. In the gasifier of FIG. 6, the supply of the gasification raw material 11 and the sealing of the furnace pressure related thereto are performed in the same manner as the mechanism for discharging the non-combustible material shown in FIG. This is performed using a combination of the first and second swing valves 18. The compression feeder 13 has been removed. In the embodiment of FIG. 6, gas leaking from the furnace into the first swing valve 18 is returned to the furnace via the discharge valve 22 and a blower (not shown). After the first swing valve 18 is completely closed, the pressure equalizing valve 21 is opened, and the pressure in the swing cut valve 19 is made equal to the furnace internal pressure.
[0045]
FIG. 7 is a flowchart showing an example of the purification process of the product gas produced by the gasifier of the present invention. In the refining process of FIG. 7, the gasification raw material 11 and the fluidizing gases 7 and 8 are supplied to the gasification apparatus 1. The combustible gas generated in the gasifier 1 recovers heat in the waste heat boiler 31, is cooled, and is sent to the cyclone separator 32, where solids 37 and 38 are separated. Thereafter, the generated gas is washed and cooled by water in the water washing tower 33, and hydrogen sulfide is removed in the alkali washing tower 34, and then stored in the gas holder 35. The unreacted char 37 in the solids separated by the cyclone separator 32 is returned to the gasifier 1, and the remaining solids 38 are discharged out of the system. As in the embodiment of FIG. 5, of the non-combustibles discharged from the gasifier 1, large non-combustibles 27 are discharged out of the system, and sand is returned to the gasifier 1. The wastewater discharged from the washing towers 33 and 34 is introduced into a wastewater treatment device 36 and is treated for detoxification.
[0046]
FIG. 8 is a flowchart showing an example of a process in which the combustible product gas and the fine particles generated in the gasifier 1 are introduced into the melting and burning furnace 41 and are burned at a high temperature to melt the ash. In the process of FIG. 8, the product gas having a high flammability produced by the gasifier 1 is introduced into the melting and burning furnace 41. Oxygen, a mixed gas of oxygen and air, or air is blown into the melting and burning furnace 41, the generated gas and fine particles are burned at 1300 ° C. or more, ash is melted, and harmful substances such as dioxin and PCB are decomposed. You. The ash 44 melted in the melting and burning furnace 41 is quenched, turned into slag, and reduced in weight. The combustion exhaust gas generated in the melting and burning furnace 41 is quenched by a scrubber 42 to prevent re-synthesis of dioxin. The exhaust gas quenched by the scrubber 41 is further filtered to remove the dust 38 and discharged from the exhaust tower 55 to the atmosphere.
[0047]
FIG. 9 is a vertical sectional perspective view of a gasification and melting and burning apparatus according to a fifth embodiment of the present invention. 9, the gasifier 1 is almost the same as the embodiment of FIG. 1, but the gas outlet 108 is connected to the combustible gas inlet 142 of the melting and burning furnace 41. The melt-burning furnace 41 includes a cylindrical primary combustion chamber 140 having a substantially vertical axis, and a secondary combustion chamber 150 inclined horizontally. The combustible gas 120 and fine particles generated in the fluidized bed furnace 2 are supplied to the primary combustion chamber 140 via the combustible gas inlet 142 so as to swirl around its axis.
[0048]
The primary combustion chamber 140 includes a starter burner at an upper end and a plurality of air nozzles 134 that supply combustion air in a swirling manner about an axis. The secondary combustion chamber 150 communicates with the primary combustion chamber 140 at the lower end thereof, and is disposed at a lower portion of the secondary combustion chamber and capable of discharging the molten ash, and an exhaust port disposed above the discharge port 152. An opening 154, an auxiliary burner 136 disposed near a portion communicating with the primary combustion chamber, and an air nozzle 134 for supplying combustion air are provided. The exhaust port 154 includes a radiation plate 162 to reduce the amount of heat lost from the exhaust port 154 due to radiation.
[0049]
FIG. 10 is a layout view of a fluidized bed gasification and melting and combustion apparatus according to an embodiment of the present invention used in combination with a waste heat boiler and a turbine. In FIG. 10, the gasifier 1 includes a conveyor 172 that conveys the large incombustibles 27 discharged from the discharger 23 and the fine noncombustibles 28 discharged from the classifier 25 together. An air jacket 185 is arranged around the conical chute 16 for taking out incombustibles from the lower part of the fluidized-bed furnace 2, and the air in the air jacket 185 is heated by hot extraction sand. The auxiliary fuel F is supplied to the primary and secondary combustion chambers 140 and 150 of the melting and burning furnace 41. The molten ash 44 discharged from the discharge port 152 of the melting and burning furnace 41 is received in the water chamber 178, rapidly cooled, and discharged as slag 176.
[0050]
In FIG. 10, the combustion gas discharged from the melting and burning furnace 41 is discharged to the atmosphere via the waste heat boiler 31, the economizer 183, the air preheater 186, the dust collector 43, and the induction ventilator 54. The combustion gas discharged from the air preheater 186 is added with a neutralizing agent N such as slaked lime before entering the dust collector 43. After the water W is supplied to the economizer 183 and preheated, the water W is heated by the boiler 31 and turned into steam, and drives the steam turbine ST. After the air A is supplied to the air preheater 186 and heated, the air A is further heated in the air jacket 185 and supplied to the melting and burning furnace 41 and, if necessary, the free board 102 via the air pipe 184.
[0051]
The fine particles 180 and 190 collected at the bottom of the waste heat boiler 31, the economizer 183, and the air preheater 186 are conveyed to the classifier 25 by the sand circulation elevator 24 to remove fine incombustibles 28, and returned to the fluidized bed furnace 2. . The fly ash 38 separated in the filter 43 contains alkali metal salts such as Na and K volatilized at a high temperature, and is thus treated by a chemical in the processor 194.
[0052]
In the apparatus of FIG. 10, the combustion in the fluidized-bed furnace 2 is a low-temperature partial combustion at a low air ratio, and a high-calorie combustible gas can be generated by maintaining the fluidized-bed temperature at 450 ° C. to 650 ° C. it can. In addition, since combustion is performed in a reducing atmosphere at a low air ratio, iron and aluminum are obtained as non-oxidized valuables in non-combustibles. The high-calorie combustible gas and char generated in the fluidized bed furnace 2 can be burned at a high temperature of 1300 ° C. or more in the melting and burning furnace 41 to melt ash and decompose dioxin.
[0053]
FIG. 11 is a layout diagram of a fluidized bed gasification and melting and combustion apparatus according to an embodiment of the present invention used in combination with the gas cooling chamber 280. 11, the gasifier 1, the melting and burning furnace 41, the water chamber 178, the dust collector 43, the induction ventilator 54, and the like are the same as those in FIG. In FIG. 11, a gas cooler 280 and an independent air preheater 188 are provided in place of the waste heat boiler, and the gas cooler 280 is supplied from the melting and burning furnace 41 through a high-temperature duct 278 covered with refractory and heat-insulating material. To be introduced. In the gas cooler 280, the combustion gas is instantaneously cooled by the fine water spray to prevent re-synthesis of dioxin. The exhaust gas flow velocity of the high-temperature duct 278 is set to a low speed of 5 m / sec or less. A hot water generator 283 is arranged above the gas cooler 280. The air heated by the air preheater 188 is supplied to the free board 102 of the gasification furnace 1 and the melting and burning furnace 41.
[0054]
FIG. 12 is a layout diagram of a fluidized bed gasification and melting and burning apparatus according to an embodiment of the present invention used in combination with the waste heat boiler 31 and the reaction tower 310. 12, the gasifier 1, the melting and burning furnace 41, the water chamber 178, the waste heat boiler 31, the steam turbine ST, the economizer 183, the air preheater 186, the dust collector 43, the inducing fan 54, and the like are the same as FIG. The same is true. In FIG. 12, a reaction tower 310 and a superheater heating combustor 320 are disposed between the waste heat boiler 31 and the economizer 183. In the reaction tower 310, a neutralizing agent N such as slaked lime slurry is added to the combustion exhaust gas to remove HCl. The solid fine particles 312 discharged from the reaction tower 310 are sent to the classifier 25 by the sand circulation elevator 24 together with the solid fine particles 180 discharged from the waste heat boiler 31. In the heating combustor 320, the unburned gas and the auxiliary fuel F are burned, and the steam temperature is raised to about 500 ° C. In the apparatus shown in FIG. 12, the power generation efficiency can be about 30% because the steam has a high temperature and a high pressure and the air ratio is small and the sensible heat taken out of the exhaust gas is small.
[0055]
FIG. 13 is a layout view of a gasification cogeneration type fluidized bed gasification and fusion combustion apparatus according to an embodiment of the present invention. 13, a gasifier 1, a melting and burning furnace 41, a water chamber 178, a waste heat boiler 31, a dust collector 43, an induction fan 54, and the like are the same as those in FIG. In FIG. 13, a reaction tower 310 is disposed between the waste heat boiler 31 and the dust collector 43. In the reaction tower 310, a neutralizing agent N such as slaked lime slurry is added to the combustion exhaust gas to remove HCl. The exhaust gas from the reaction tower 310 is used in the gas turbine 420 via the dust collector 43. In the gas turbine 420, the air A is compressed by the compressor C and supplied to the combustor CC, and the fuel F is combusted in the combustor CC. Is the working fluid of the turbine T. The exhaust gas of the gas turbine 420 passes through the superheater 430, the economizer 440, and the air preheater 450 in this order, and is discharged to the atmosphere by the induction ventilator 54. The steam generated in the waste heat boiler 31 is heated by the exhaust gas of the gas turbine 420 in the super heater 430 and supplied to the steam turbine ST.
[0056]
FIG. 14 is a flow chart showing the steps of the fluidized bed gasification and melt combustion method of the combined pressurized gasification power generation type of the embodiment of the present invention. The high-temperature and high-pressure generated gas 29 generated in the pressurized gasification furnace 1 is introduced into a waste heat boiler 31 ′, which generates steam and is itself cooled. The product gas exiting the waste heat boiler is divided into two parts, one of which is added to the melting and burning furnace 41 and the other is added with the neutralizing agent N to neutralize HCl and is introduced into the dust collector 43 '. In the dust collector 43 ', the low-melting substance in the product gas solidified by the temperature drop is separated from the product gas, sent to the melting and burning furnace 41, and melted. The product gas from which the low melting point material has been removed is used as a fuel gas in the gas turbine GT. Exhaust gas of the gas turbine GT is heat-exchanged by a super heater SH and an economizer ECo, and then processed by an exhaust gas processor 510 to be released into the atmosphere. The exhaust gas from the melting and burning furnace 41 is introduced into an exhaust gas processor 510 via a heat exchanger EX and a dust collector 43. The molten ash 44 discharged from the melting furnace is rapidly cooled into slag. The solid matter 38 discharged from the dust collector 43 is subjected to chemical treatment in a processor 194.
[0057]
According to the process of FIG. 14, the gas generated from the waste is used as a fuel after the HCl and solids are removed, so that the gas turbine is not corroded and the HCl is removed. Therefore, high-temperature steam can be generated by the gas turbine exhaust gas.
[0058]
【The invention's effect】
(1) In the gasifier of the present invention, heat is diffused by the circulating flow of the fluidized-bed furnace, so that the load can be increased and the furnace can be downsized.
[0059]
(2) In the present invention, since the fluidized-bed furnace can maintain combustion with a small amount of air, the fluidized-bed furnace is set to a low air ratio and low temperature (450 to 650 ° C.) to minimize heat generation and slowly burn. By doing so, a homogeneous product gas containing a large amount of flammable components can be obtained, and most of the flammable components of gas, tar, and char can be used in the next-stage fusion combustion furnace.
[0060]
(3) In the present invention, large incombustibles can be easily discharged by the circulating flow of the fluidized bed furnace. In addition, iron and aluminum in incombustibles can be used as unoxidized valuables.
[0061]
(4) According to the present invention, there is provided a method or equipment which makes garbage disposal harmless and has a high energy utilization rate.
[Brief description of the drawings]
FIG. 1 is a schematic vertical sectional view of a main part of a gasifier according to a first embodiment of the present invention.
FIG. 2 is a schematic horizontal sectional view of a fluidized bed furnace of the gasifier of FIG.
FIG. 3 is a schematic vertical sectional view of a main part of a gasifier according to a second embodiment of the present invention.
FIG. 4 is a schematic horizontal sectional view of a fluidized bed furnace of the gasifier of FIG. 2;
FIG. 5 is a schematic vertical sectional view of a gasifier according to a third embodiment of the present invention.
FIG. 6 is a schematic vertical sectional view of a gasifier according to a fourth embodiment of the present invention.
FIG. 7 is a flowchart showing an example of a purification process of a product gas.
FIG. 8 is a flowchart showing an example of a process in which ash is melted.
FIG. 9 is a schematic vertical sectional perspective view of a gasification and melting and burning apparatus according to a fifth embodiment of the present invention.
FIG. 10 is a layout diagram of a fluidized bed gasification and melting and combustion apparatus according to an embodiment of the present invention used in combination with a waste heat boiler and a turbine.
FIG. 11 is a layout view of a fluidized bed gasification and melting and combustion apparatus according to an embodiment of the present invention used in combination with a gas cooling chamber.
FIG. 12 is a layout view of a fluidized bed gasification and melting and combustion apparatus according to an embodiment of the present invention used in combination with a waste heat boiler and a reaction tower.
FIG. 13 is a layout diagram of a fluidized bed gasification and fusion combustion apparatus according to a gasification cogeneration type embodiment of the present invention.
FIG. 14 is a flow chart showing the steps of a fluidized bed gasification and melt combustion method according to an embodiment of the combined pressurized gasification power generation type of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1; Gasification apparatus, 2; Fluidized bed furnace, 3; Furnace bottom peripheral part, 4; Furnace bottom central part, 5; Noncombustible material discharge port, 6; Inclined wall, 7; Central fluidizing gas, 7 '; Gasification gas, 8; Peripheral fluidization gas, 9; Moving bed, 9 '; Intermediate layer, 10; Fluidized bed, 11; Gasification raw material (combustible material), 12; Double damper, 13; Compression feeder, 14; Feeder, 15; Roots blower, 16; Conical chute, 17; Constant discharger, 18, 20; Swing valve, 19, 19 '; Swing cut valve, 22; Discharge valve, 23; Continuous discharger with trommel, 24; Recirculation elevator, 25; Classifier, 27, 28; Noncombustible, 29; Product gas, 31, 31 '; Waste heat boiler, 32; Cyclone separator, 36; Wastewater treatment unit, 37; Unreacted char, 38; Min, 41; melting and burning furnace, 43, 43 '; dust collector, 44; melting Induction ventilator, 55; Exhaust tower, 102; Free board, 104; Combustible material supply port, 106; Gas dispersion mechanism, 108; Gas outlet, 114; Char tar, 134; Combustion burner, 140; Primary combustion Combustion gas inlet, 150; Secondary combustion chamber, 162; Radiant plate, 176; Slag, 178; Water chamber, 183; Economizer, 185; Air jacket, 186, 188; Air preheater, 194, 510; Processor, 280; Gas cooler, 310; Reaction tower, 320; Super heater heating combustor, 420; Gas turbine, A; Air, C; Compressor, CC; Combustor, Eco; Economizer, F: Auxiliary fuel, G: gasification zone, N: neutralizer, S: oxidation zone, SH: super heater, ST: steam turbine, T: turbine, W: water.

Claims (30)

After gasifying the waste, in the device that melts the ash,
A fluidized bed furnace having a circulating flow of a fluidized medium consisting of a fluidized medium rising and a fluidized medium settling down, wherein the waste is gasified to generate gas and char, and the temperature of the fluidized bed at which the fluidized medium rises Is maintained at 450 ° C. to 650 ° C. so that the suppressed combustion reaction is continued,
A gasification and melting apparatus comprising a melting furnace for supplying the gas and the char from the fluidized bed furnace to melt ash. After gasifying the waste, in the device that melts the ash,
A fluidized bed furnace having a circulating flow of a fluidized medium formed by a fluidizing gas having a relatively high mass velocity and a fluidizing gas having a relatively low mass velocity by supplying air as a fluidizing gas into the furnace; The material is gasified to generate gas and char, and the temperature of the fluidized bed fluidized by the fluidizing gas having a relatively high mass velocity is maintained at 450 ° C. to 650 ° C. so that the suppressed combustion reaction is continued. West,
A gasification and melting apparatus comprising a melting furnace for supplying the gas and the char from the fluidized bed furnace to melt ash. The gasification and melting apparatus according to claim 1, wherein the fluid medium is raised by a fluidizing gas having a relatively high mass velocity. The circulating flow of the fluid medium comprising the rising fluid medium and the settling fluid medium is formed by a fluidizing gas having a relatively high mass velocity and a fluidizing gas having a relatively low mass velocity. 2. A gasification and melting apparatus according to claim 1. 5. The gasification and melting apparatus according to claim 1, wherein air is supplied as a fluidizing gas into the fluidized bed furnace. After gasifying the waste, in the device that melts the ash,
A fluidized bed furnace having a circulating flow of a fluidized medium consisting of a fluidized medium rising and a fluidized medium settling down, wherein the waste is gasified to generate gas and char, and the temperature of the fluidized bed at which the fluidized medium rises Is maintained at 450 ° C. to 650 ° C., and a part of the produced char is burned in a fluidized bed in which a fluidized medium rises.
A gasification and melting apparatus comprising a melting furnace for supplying the gas and the char from the fluidized bed furnace to melt ash. After gasifying the waste, in the device that melts the ash,
A fluidized bed furnace having a circulating flow of a fluidized medium formed by a fluidizing gas having a relatively high mass velocity and a fluidizing gas having a relatively low mass velocity by supplying air as a fluidizing gas into the furnace; The material is gasified to produce gas and char, the temperature of the fluidized bed fluidized by the fluidizing gas having a relatively high mass velocity is maintained at 450 ° C. to 650 ° C., and a part of the produced char is mass-velocated. Combustion in a fluidized bed fluidized by a relatively large fluidizing gas of
A gasification and melting apparatus comprising a melting furnace for supplying the gas and the char from the fluidized bed furnace to melt ash. The gasification and melting apparatus according to claim 6, wherein the fluid medium is raised by a fluidizing gas having a relatively high mass velocity. 7. The circulating flow of a fluidized medium comprising a rising fluidized medium and a settling fluidized medium is formed by a fluidized gas having a relatively large mass velocity and a fluidized gas having a relatively small mass velocity. 2. A gasification and melting apparatus according to claim 1. 10. The gasification and melting apparatus according to claim 6, wherein air is supplied as a fluidizing gas into the fluidized bed furnace. The gasification and melting apparatus according to any one of claims 1 to 10, wherein the waste is municipal waste or waste plastic. The gasification and melting apparatus according to any one of claims 1 to 11, wherein the melting furnace includes a nozzle for supplying oxygen or a mixed gas of oxygen and air. The gasification and melting apparatus according to any one of claims 1 to 12, wherein the gas and the char supplied from the fluidized bed furnace are burned at 1300 ° C or more in the melting furnace. The gasification and melting apparatus according to any one of claims 1 to 13, wherein the fluidized bed furnace has a low air ratio. The gasification and melting according to any one of claims 1 to 14, wherein an air amount of the entire fluidized gas supplied into the fluidized bed furnace is set to 30% or less of a theoretical combustion air amount. apparatus. The gasification and melting apparatus according to any one of claims 1 to 15, wherein a plurality of fluidizing gas supply means for supplying a fluidizing gas into the fluidized bed furnace are provided. In the method of melting ash after gasifying waste,
The waste is supplied to a fluidized bed furnace having a circulating flow of a fluidized medium consisting of a fluidized medium rising in the furnace and a fluidized medium settling, and the waste is gasified to produce gas and char. Maintaining the temperature between 450 ° C. and 650 ° C. so that the suppressed combustion reaction is continued;
A method for treating waste, comprising supplying said gas and said char from said fluidized bed furnace to a melting furnace to melt ash. In the method of melting ash after gasifying waste,
Air is supplied as a fluidizing gas into the furnace, and the waste is put into a fluidized bed furnace having a circulating flow of a fluidizing medium formed by a fluidizing gas having a relatively large mass velocity and a fluidizing gas having a relatively small mass velocity. The gas is supplied and gasified to generate gas and char, and the temperature of the fluidized bed fluidized by the fluidizing gas having a relatively high mass velocity is maintained at 450 ° C. to 650 ° C., and the suppressed combustion reaction is continued. Like
A method for treating waste, comprising supplying said gas and said char from said fluidized bed furnace to a melting furnace to melt ash. 18. The method of claim 17, wherein the fluid medium is raised by a fluidizing gas having a relatively high mass velocity. The circulating flow of the flowing medium comprising the rising flowing medium and the settling flowing medium is formed by a fluidizing gas having a relatively high mass velocity and a fluidizing gas having a relatively low mass velocity. The waste disposal method described in 1. In the method of melting ash after gasifying waste,
The waste is supplied to a fluidized bed furnace having a circulating flow of a fluidized medium consisting of a fluidized medium rising in the furnace and a fluidized medium settling, and the waste is gasified to produce gas and char. Maintaining the temperature between 450 ° C. and 650 ° C., burning part of the produced char in a fluidized bed in which the fluidized medium rises,
A method for treating waste, comprising supplying said gas and said char from said fluidized bed furnace to a melting furnace to melt ash. In the method of melting ash after gasifying waste,
Air is supplied as a fluidizing gas into the furnace, and the waste is put into a fluidized bed furnace having a circulating flow of a fluidizing medium formed by a fluidizing gas having a relatively large mass velocity and a fluidizing gas having a relatively small mass velocity. The gas is supplied and gasified to produce gas and char, the temperature of the fluidized bed fluidized by the fluidizing gas having a relatively high mass velocity is maintained at 450 ° C. to 650 ° C., and a part of the produced char is mass-produced. Combustion in a fluidized bed fluidized by a relatively high velocity fluidizing gas,
A method for treating waste, comprising supplying said gas and said char from said fluidized bed furnace to a melting furnace to melt ash. 22. The method of claim 21, wherein the fluid medium is raised by a fluidizing gas having a relatively high mass velocity. 22. The circulating flow of a fluid medium comprising a rising fluid medium and a falling fluid medium is formed by a fluidizing gas having a relatively high mass velocity and a fluidizing gas having a relatively low mass velocity. The waste disposal method described in 1. The waste treatment method according to any one of claims 17 to 24, wherein the waste is municipal waste or waste plastic. The method according to any one of claims 17 to 25, wherein oxygen or a mixed gas of oxygen and air is supplied to the melting furnace. The method for treating waste according to any one of claims 17 to 26, wherein the gas and the char supplied from the fluidized bed furnace are burned at 1300 ° C or higher in the melting furnace. The method for treating waste according to any one of claims 17 to 27, wherein the fluidized bed furnace has a low air ratio. The waste treatment according to any one of claims 17 to 28, wherein the air amount of the entire fluidized gas supplied into the fluidized bed furnace is set to 30% or less of the theoretical combustion air amount. Method. The method for treating waste according to any one of claims 17 to 29, wherein the fluidized gas is supplied into the fluidized bed furnace by a plurality of fluidized gas supply units.

Images