JP3564040B2 - Exhaust heat recovery equipment in melting furnace - Google Patents

Exhaust heat recovery equipment in melting furnace Download PDF

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JP3564040B2
JP3564040B2 JP2000125690A JP2000125690A JP3564040B2 JP 3564040 B2 JP3564040 B2 JP 3564040B2 JP 2000125690 A JP2000125690 A JP 2000125690A JP 2000125690 A JP2000125690 A JP 2000125690A JP 3564040 B2 JP3564040 B2 JP 3564040B2
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combustion
cylinder
combustion air
combustion chamber
exhaust gas
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JP2001304524A (en
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仁 秋山
知彦 平尾
聡 吉本
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株式会社タクマ
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【0001】
【発明の属する技術分野】
本発明は、例えばごみ焼却炉から排出される焼却残渣や飛灰、或いは下水汚泥や破砕不燃物等の被溶融物を溶融処理する溶融炉を備えた溶融処理設備に用いられるものであり、溶融炉から排出された排ガスを二次燃焼する二次燃焼塔としての機能と、高温の排ガスから熱回収する空気予熱器としての機能を併せ持つ溶融炉に於ける排熱回収装置に関するものである。
【0002】
【従来の技術】
近年、ごみ焼却炉から排出される焼却残渣や飛灰(以下被溶融物と云う)の減容化及び無害化を図る為、被溶融物の溶融固化処理法が注目され、現実に実用に供されている。何故なら、被溶融物は溶融固化することにより、その容積を1/2〜1/3に減らすことができると共に、物理的・化学的に安定して重金属等の有害物質の溶出防止やダイオキシン類の完全分解が可能になるうえ、コンクリートフィラー材、路盤材、ブロック等としての再利用や最終埋立処分場の延命等が可能になるからである。
【0003】
而して、前記被溶融物の溶融固化処理方法には、アーク溶融炉やプラズマアーク炉、電気抵抗炉等の電気式溶融炉を使用し、電気エネルギーによって被溶融物を溶融した後、これを水冷若しくは空冷により固化する方法と、表面溶融炉や旋回溶融炉、コークスベッド炉等の燃焼式溶融炉を使用し、灯油や天然ガス等の化石燃料の燃焼エネルギーによって被溶融物を溶融した後、これを水冷若しくは空冷により固化する方法とが多く利用されて居り、被溶融物の溶融処理設備に発電設備が併置されている場合には、前者の電気エネルギーを用いる方法が、又、発電設備が併置されていない場合には、後者の燃焼エネルギーを用いる方法が夫々多く採用されている。
【0004】
図5は表面溶融炉を用いた被溶融物の溶融処理設備の一例を示す概略系統図であり、図5に於いて、40は表面溶融炉、41は高温煙道、42は二次燃焼塔、43は二次燃焼用空気吹込みノズル、44は二次燃焼用空気供給管、45は二次燃焼用空気送風機、46はガス冷却用送風機、47は空気予熱器、48は表面溶融炉用バーナ62への燃焼用空気供給管、49は押込み送風機、50はガス冷却装置、51は冷却水、52は活性炭、消石灰及び助剤の供給管、53は集塵装置、54は飛灰搬出コンベヤ、55は触媒脱硝塔、56は誘引通風機、57は煙突である。
【0005】
前記表面溶融炉40は、灯油や天然ガス等の化石燃料の燃焼熱を熱源とするものであり、炉内に4方向から被溶融物が供給されて傾斜状の溶融面を形成する4面式構造若しくは炉内に対面2方向から被溶融物が供給されて傾斜状の溶融面を形成する対面式構造となっている。
即ち、表面溶融炉40は、図1に示す如く、炉本体58と、炉本体58廻りの4方向若しくは対面2方向に設けたホッパ59と、各ホッパ59に被溶融物Wを分配投入する被溶融物分配供給装置60と、各ホッパ59に投入された被溶融物Wを炉内へ供給する被溶融物押出し装置61と、炉内の被溶融物Wを表面側から加熱溶融する1台若しくは複数台のバーナ62と、溶融スラグを排出するスラグタップ63と、スラグタップ63から流下した溶融スラグを水砕(若しくは空冷)して排出する水封式スラグコンベヤ64(若しくは空冷式スラグコンベヤ)等から構成されており、当該表面溶融炉40には高温煙道41を介して二次燃焼塔42及び空気予熱器47等が順次接続されている。
【0006】
前記二次燃焼塔42は、内部に二次燃焼室Sを有する円筒状の耐火物構造となっており、二次燃焼塔42の下部位置には二次燃焼室S内に旋回を与える二次燃焼用空気吹込みノズル43が設けられている。
又、空気予熱器47は、図6に示す如く、直径の異なる鋼板製の内筒65及び外筒66を同心円上に配設して成る二重円筒構造となっており、内筒65の内部を高温の排ガスGが流れることによって内筒65と外筒66の間を流れるバーナ62用の燃焼用空気Aを加熱するようになっている。この空気予熱器47は、温度上昇により生じる内筒65と外筒66との間の熱膨張を伸縮継手67により吸収するようになっている。
【0007】
而して、前記溶融処理設備に於いて、被溶融物分配供給装置60により各ホッパ59内に分配投入された焼却残渣等の被溶融物Wは、被溶融物押出し装置61により炉本体58内へ順次送り込まれ、表面がスラグタップ63を中心にして略すり鉢状の傾斜面となった状態で炉底に堆積され、バーナ62の燃焼熱によって表面側から順次加熱・溶融されてフィルム状の溶融スラグとなる。この溶融スラグは、すり鉢状の傾斜面を流下してスラグタップ63から水封式スラグコンベヤ64上へ落下し、冷却水により冷却固化されて水砕スラグとなった後、水封式スラグコンベヤ64により排出されて行く。
【0008】
一方、炉本体58内の高温の燃焼排ガスGは、溶融スラグと共にスラグタップ63から排出され、高温煙道41を通って二次燃焼塔42内に送り込まれる。二次燃焼塔42内に送り込まれた燃焼排ガスGは、二次燃焼用空気吹込みノズル43から二次燃焼室S内に吹き込まれる二次燃焼用空気A′により二次燃焼室S内に於いて二次燃焼される。これにより、排ガスG中に含まれる未燃ガスは、二次燃焼室S内に於いて十分な滞留時間と温度をもって完全燃焼される。
そして、完全燃焼された排ガスGは、引き続き空気予熱器47に入り、ここで押込み送風機49から空気予熱器47へ送り込まれたバーナ62用の燃焼用空気Aを約350℃まで加熱した後、ガス冷却装置50、集塵装置53、触媒脱硝塔55、誘引通風機56及び煙突57を経てクリーンガスとなって大気中に放出される。
【0009】
【発明が解決しようとする課題】
ところで、上述した溶融処理設備のように二次燃焼塔42と空気予熱器47を別個の装置として設置している場合には次の▲1▼〜▲4▼のような問題がある。
▲1▼ 二次燃焼塔42は排ガスG中の未燃ガスを完全燃焼させる為に十分な大きさが必要であり、又、空気予熱器47も排ガスGからの熱回収を行う為に十分な伝熱面積が必要であり、二次燃焼塔42及び空気予熱器47は何れも大きな装置となる。その結果、二次燃焼塔42と空気予熱器47を別個に設置する為のスペースが必然的に大きなものとなり、建築コストや設備コストが増大すると云う問題がある。
▲2▼ 空気予熱器47の内筒65が排ガスGと直接接触する為、内筒65の内周面温度が内筒65材質の最高使用温度以下となるように排ガスGの温度を650℃付近まで下げる必要がある。しかし、二次燃焼塔42の出口付近の排ガス温度が900℃近くある為、排ガスGを冷却する為に空気予熱器47の手前で冷却空気若しくは冷却水を吹き込まなければならず、排ガスGの排出量が増加すると云う問題がある。
▲3▼ 二次燃焼塔42では排ガスGを850℃以上の高温で十分な滞留時間をもって完全燃焼することによりダイオキシン類を分解するが、空気予熱器47では内筒65と外筒66との間を流れる燃焼用空気Aの温度により、内筒65の内周面付近を流れる排ガスGの境界層でダイオキシン類が再合成され易い温度域(300℃付近)を作ってしまうと云う問題がある。
▲4▼ 表面溶融炉40から排出される排ガスGは被溶融物Wの性状等によっては排ガスG中に含まれるHClが数千ppmと高く、更に空気予熱器47の内筒65の内周面に溶融塩類を主とした溶融ダストが付着する為、空気予熱器47の内筒65の内周面に腐食を引き起こすと云う問題がある。
【0010】
本発明は、このような問題点に鑑みて為されたものであり、その目的は用途の異なる別個の装置として設置していた二次燃焼塔と空気予熱器を一体化して設備のコンパクト化及びコスト低減を図ると共に、ダイオキシン類の再合成防止や排ガスによる腐食防止を可能とした溶融炉に於ける排熱回収装置を提供することにある。
【0011】
【課題を解決するための手段】
上記目的を達成するため、本発明の請求項1の発明は、溶融炉から排出された排ガス中の未燃ガスを完全燃焼させると共に、この排ガスから熱回収して燃焼用空気を加熱するようにした溶融炉に於ける排熱回収装置で於いて、当該排熱回収装置は、溶融炉からの排ガスが送り込まれる二次燃焼室を形成する内筒と、内筒の外側に配設されてその外周面との間に燃焼用空気が通過する環状の予熱通路を形成する外筒とから成り、排ガス中の未燃ガスを二次燃焼室内に於いて二次燃焼用空気により二次燃焼させて完全燃焼させると共に、予熱通路内を通過する燃焼用空気を二次燃焼室内の高温の排ガスにより内筒を通して加熱するようにした溶融炉に於ける排熱回収装置であって、二次燃焼室を形成する内筒を、金属製の円筒の内周面に耐食性及び熱伝導性に優れた耐火物を内張りして成る内筒とすると共に、二次燃焼室の上流側位置に二次燃焼用空気吹込みノズルを設け、当該二次燃焼用空気吹込みノズルから内筒の内周面に沿ってその接線方向に二次燃焼用空気を吹き込んで二次燃焼室内に旋回流を形成するようにしたことを発明の基本構成とするものである。
【0012】
本発明の請求項2の発明は、溶融炉から排出された排ガス中の未燃ガスを完全燃焼させると共に、この排ガスから熱回収して燃焼用空気を加熱するようにした溶融炉に於ける排熱回収装置で於いて、当該排熱回収装置は、溶融炉からの排ガスが送り込まれる二次燃焼室を形成する内筒と、内筒の外側に配設されてその外周面との間に燃焼用空気が通過する環状の予熱通路を形成する外筒とから成り、排ガス中の未燃ガスを二次燃焼室内に於いて二次燃焼用空気により二次燃焼させて完全燃焼させると共に、予熱通路内を通過する燃焼用空気を二次燃焼室内の高温の排ガスにより内筒を通して加熱するようにした溶融炉に於ける排熱回収装置であって、二次燃焼室を形成する内筒を多孔質性の耐火物により円筒状に形成し、予熱通路内を通過する燃焼用空気を耐火物からの熱伝導により加熱すると共に、予熱通路内の燃焼用空気の一部が二次燃焼用空気として多孔質性の耐火物の孔から二次燃焼室内へ流れ込むようにしたことを発明の基本構成とするものである。
【0013】
本発明の請求項3の発明は、二次燃焼室の上流側位置に二次燃焼用空気吹込みノズルを設け、当該二次燃焼用空気吹込みノズルから内筒の内周面に沿ってその接線方向に二次燃焼用空気を吹き込んで二次燃焼室内に旋回流を形成するようにしたものである。
【0014】
本発明の請求項4の発明は、二次燃焼室を形成する内筒を多孔質性の耐火物により円筒状に形成し、予熱通路内を通過する燃焼用空気を耐火物からの熱伝導により加熱すると共に、予熱通路内の燃焼用空気の一部が二次燃焼用空気として多孔質性の耐火物の孔から二次燃焼室内へ流れ込むようにしたことに特徴がある。
【0016】
前記排熱回収装置1は、表面溶融炉2から高温煙道10を通って来た高温の燃焼排ガスG中の未燃ガスを完全燃焼させると共に、この排ガスGから熱回収してバーナ7用の燃焼用空気A(若しくはバーナ7用の燃焼用空気A及び二次燃焼用空気A′の両方)を加熱するものであり、従来の二次燃焼塔としての機能と空気予熱器としての機能を併せ持つものである。
【0017】
即ち、排熱回収装置1は、高温煙道10を通って来た高温の燃焼排ガスGが送り込まれる横断面形状が円形の二次燃焼室Sを形成する内筒24と、内筒24の外周面との間にバーナ7用の燃焼用空気Aが通過する環状の予熱通路S′を形成する外筒25と、二次燃焼室S内に二次燃焼用空気A′を吹き込む二次燃焼用空気吹込みノズル11等から成り、排ガスG中の未燃ガスを二次燃焼室S内に於いて二次燃焼用空気A′により二次燃焼させて完全燃焼させると共に、予熱通路S′内のバーナ7用の燃焼用空気Aを二次燃焼室S内の排ガスGにより内筒24を通して加熱するようにしたものである。
【0018】
具体的には、前記内筒24は、図2に示す如く、鋼板製の円筒24aの内周面に耐食性及び熱伝導性に優れた耐火物26を内張りすることにより形成されている。この耐火物26には、HCl等の腐食性ガスやNaCl、KCl等の溶融塩を主とした付着ダストに対して耐食性を有し、且つ熱伝導性に優れたキャスタブル耐火物等の不定形耐火物や耐火れんが等の定形耐火物が使用されている。
【0019】
前記外筒25は、図2に示す如く、鋼板材により内筒24よりも大径の円筒状に形成されており、内筒24の外周囲に同心円上に配置されて内筒24の外周面との間にバーナ7用の燃焼用空気Aが通過する環状の予熱通路S′を形成するものである。
この外筒25の下端部側には予熱通路S′へ新鮮な燃焼用空気Aを供給する入口27が形成されており、当該入口27は燃焼用空気供給管14を介して押込み送風機15に接続されている。又、外筒25の上端部側には予熱通路S′内で加熱された燃焼用空気Aが流出する出口28が形成されており、当該出口28は燃焼用空気供給管14を介してバーナ7に接続されている。
【0020】
前記内筒24及び外筒25は、その上端部同士が気密状に接続されていると共に、その下端部同士が伸縮継手29を介して気密状に接続されており、温度上昇によって内筒24と外筒25との間に生じる熱膨張を伸縮継手29により吸収する構造となっている。
【0021】
前記二次燃焼用空気吹込みノズル11は、図2及び図3に示す如く、二次燃焼室Sの上流側位置(図2の下方側位置)の数箇所に設けられており、内筒24の内周面に沿ってその接線方向に二次燃焼用空気A′を吹き込んで二次燃焼室S内に旋回流を形成できるようになっている。この二次燃焼用空気吹込みノズル11は、二次燃焼用空気供給管12を介して押込み送風機15に接続されている。
【0022】
そして、前記排熱回収装置1は、その上流側端部(図2の下方側端部)が表面溶融炉2から排出された高温の燃焼排ガスGが流れる高温煙道10に連通状に接続されていると共に、その下流側端部(図2の上方側端部)が冷却装置16に連通状に接続されており、高温煙道10から送られて来た排ガスGを二次燃焼室S内に於いて二次燃焼用空気A′により二次燃焼させてからガス冷却装置16内へ送ると共に、予熱通路S′内を流れるバーナ7用の燃焼用空気Aを加熱するようになっている。
【0023】
次に、上述した排熱回収装置1を備えた溶融処理設備を用いて焼却残渣等の被溶融物Wを溶融処理する場合について説明する。
ごみ焼却炉から排出された焼却残渣等の被溶融物Wは、被溶融物分配供給装置5により各ホッパ4内に分配投入された後、被溶融物押出し装置6により溶融炉本体3内へ順次送り込まれ、表面がスラグタップ8を中心にして略すり鉢状の傾斜面となった状態で炉底に堆積される。
【0024】
炉底に堆積した被溶融物Wは、バーナ7からの燃焼火炎によって1300℃〜1400℃の高温に加熱され、表面側から順次溶融されてフィルム状の溶融スラグとなる。この溶融スラグは、すり鉢状の傾斜面を流下してスラグタップ8から水封式スラグコンベヤ9上へ落下し、冷却水により冷却固化されて水砕スラグとなった後、水封式スラグコンベヤ9により排出されて行く。
【0025】
尚、溶融スラグが傾斜面を流下することによって、傾斜面には次々に新しい被溶融物Wが露出することになり、この露出した新しい被溶融物Wはバーナ7からの燃焼火炎によって順次フィルム状に溶融されて行く。
又、溶融の進行に伴って溶融した傾斜面が後退すると、被溶融物押出し装置6が作動してホッパ4内の新しい被溶融物Wを炉内へ押し込んで行く。これによって、被溶融物W層の溶融した傾斜面は、被溶融物Wの安息角又は安息角に近い角度に維持される。その結果、フィルム状に溶融した溶融スラグは、容易に傾斜面を流下し、直ぐに新しい被溶融物Wが露出することになり、溶融処理が迅速に行われる。
【0026】
一方、炉本体3内で発生した高温の燃焼排ガスGは、溶融スラグと一緒にスラグタップ8から排出され、高温煙道10を通って排熱回収装置1に送り込まれ、ここで二次燃焼されると共に熱回収が行われる。
即ち、排熱回収装置1の二次燃焼室S内に送り込まれた燃焼排ガスGは、二次燃焼用空気吹込みノズル11から二次燃焼室S内に吹き込まれる二次燃焼用空気A′により二次燃焼室S内に於いて二次燃焼される。このとき、二次燃焼用空気吹込みノズル11から内筒24の内周面に沿ってその接線方向に二次燃焼用空気A′を吹き込んで二次燃焼室S内に旋回流を形成するようにしている為、排ガスG中に含まれる未燃ガスは二次燃焼室S内に於いて十分な滞留時間と温度をもって攪拌・燃焼される。その結果、表面溶融炉2から排出される排ガスG中の未燃ガスは完全燃焼されることになる。
又、排熱回収装置1の予熱通路S′内には、押込み送風機15及び燃焼用空気供給管14から新鮮な燃焼用空気A(温度:約20℃)が送り込まれている。この予熱通路S′内を流れる燃焼用空気Aは、内筒24を形成する耐火物26からの熱伝導により約350℃に加熱された後、燃焼用空気供給管14を通ってバーナ7へ供給されて燃焼に利用される。
【0027】
そして、排熱回収装置1の二次燃焼室S内で二次燃焼された後の排ガスGは、引き続きガス冷却装置16へ送られ、ここで冷却水17の噴射によって200℃以下に減温された後、集塵装置19、触媒脱硝塔21、誘引通風機22及び煙突23を経てクリーンガスとなって大気中に放出される。
【0028】
このように、前記排熱回収装置1は、二次燃焼塔としての機能と空気予熱器としての機能を併せ持つ為、図5に示す従来の溶融処理設備のように用途の異なる二次燃焼塔と空気予熱器を別個に設置すると云うこともなく、設置スペースを半減できて建設コストや設備コストの大幅な削減を図れる。
又、排熱回収装置1は、内筒24が金属製の円筒24aの内周面に耐火物26を内張りすることにより形成されている為、二次燃焼室S内を流れる高温・高腐食性の排ガスGやダストが金属部材である円筒24aに直接接触すると云うことがなく、内筒24の腐食を防止することができる。然も、耐火物26を内張りすることによって、従来の空気予熱器のように排ガスGの温度を内筒材質の最高使用温度以下となるように下げる必要もなく、高温排ガスGからの熱回収が可能になると共に、空気予熱器の手前で冷却空気を吹き込む必要もなくなり、排ガスGの排出量が増大すると云うこともない。
更に、排熱回収装置1は、内筒24の内周面に内張りした耐火物26からの熱伝導により予熱通路S′内を通過するバーナ7の燃焼用空気Aを加熱するようにしている為、排ガスGと接触する耐火物26の表面温度が著しく低下することがない。その結果、内筒24の内周面付近を流れる排ガスG中にダイオキシン類の再合成し易い温度域(300℃付近)を作ることがなくなり、ダイオキシン類対策としての効果が得られる。
【0029】
図4は本発明の他の実施の形態に係る排熱回収装置1の概略断面図を示すものであり、当該排熱回収装置1は、高温煙道10を通って来た高温の燃焼排ガスGが送り込まれる二次燃焼室Sを形成する内筒24と、内筒24の外周面との間にバーナ7用の燃焼用空気Aが通過する環状の予熱通路S′を形成する外筒25等から成り、二次燃焼室Sを形成する内筒24を多孔質性の耐火物26′により円筒状に形成し、予熱通路S′内を通過するバーナ7用の燃焼用空気Aを耐火物26′からの熱伝導により加熱すると共に、予熱通路S′内の燃焼用空気Aの一部が二次燃焼空気A′として多孔質性の耐火物26′の孔から二次燃焼室S内へ流れ込むようになっている。
【0030】
前記内筒24は、多孔質性のブロック状の耐火物26′を円筒状に積み上げることにより形成されており、各耐火物26′は複数の鋼材製のフック30を介して外筒25に支持されている。即ち、各耐火物26′は、鋼材製のフック30の一端を各耐火物26′に夫々埋設すると共に、フック30の他端を外筒25の内周面に溶接等により固着することにより、外筒25に支持されている。この耐火物26′には、熱伝導性に優れていると共に予熱通路S′内を流れる燃焼用空気Aの一部が二次燃焼室S内へ流れ込むことができる耐火物26′が使用されている。
【0031】
前記外筒25は、鋼板材により内筒24よりも大径の円筒状に形成されており、内筒24の外周囲に同心円上に配置されて内筒24の外周面との間にバーナ7用の燃焼用空気Aが通過する環状の予熱通路S′を形成するものである。
この外筒25の下端部側には予熱通路S′へ新鮮な燃焼用空気Aを供給する入口27が形成されており、当該入口27は燃焼用空気A供給管14を介して押込み送風機15に接続されている。又、外筒25の上端部側には予熱通路S′内で加熱された燃焼用空気Aが流出する出口28が形成されており、当該出口28は燃焼用空気供給管14を介してバーナ7に接続されている。
【0032】
そして、前記内筒24及び外筒25は、その上端部同士が気密状に接続されていると共に、その下端部同士が伸縮継手29を介して気密状に接続されており、温度上昇によって内筒24と外筒25との間に生じる熱膨張を伸縮継手29により吸収する構造となっている。
尚、図4に於いて、31は燃焼用空気供給管14に介設したダンパ、32は燃焼用空気供給管14内を流れる燃焼用空気Aの温度や流量が所定の値になるようにダンパ31を制御する制御器である。
【0033】
而して、この排熱回収装置1に於いては、高温煙道10を通って排熱回収装置1の二次燃焼室S内に送り込まれた燃焼排ガスGの熱が内筒24を形成する耐火物26′に伝達され、耐火物26′からの熱伝導により予熱通路S′内を流れる燃焼用空気Aが約350℃に加熱される。この加熱された燃焼用空気Aは、燃焼用空気供給管14を通ってバーナ7へ供給されて燃焼に利用される。
又、予熱通路S′内の燃焼用空気Aの一部は、多孔質性の耐火物26′の孔から二次燃焼室S内へ流れ込み、二次燃焼用空気A′として使用される。これによって、二次燃焼室S内の燃焼排ガスGは、前記二次燃焼用空気A′により二次燃焼室S内に於いて二次燃焼され、排ガスG中に含まれる未燃ガスが二次燃焼室S内に於いて完全燃焼される。完全燃焼された排ガスGは、引き続きガス冷却装置16へ送られ、ここで冷却水17の噴射によって200℃以下に減温された後、集塵装置19、触媒脱硝塔21、誘引通風機22及び煙突23を経てクリーンガスとなって大気中に放出される。
【0034】
この排熱回収装置1は、上述した図2に示す排熱回収装置1と同様の作用効果を奏することができる。然も、この排熱回収装置1は、予熱通路S′内を流れるバーナ7用の燃焼用空気Aの一部が二次燃焼用空気A′として内筒24を形成する多孔質性の耐火物26′の孔を通って内筒24の内周面から二次燃焼室S内へ流れ込む為、内筒24内周面へのダストの付着を防止することができる。
【0035】
【発明の効果】
上述の通り、本発明の請求項1の排熱回収装置は、二次燃焼室を形成する内筒の周囲に外筒を配置して内筒と外筒との間に燃焼用空気が通過する環状の予熱通路を形成し、排ガス中の未燃ガスを二次燃焼室内に於いて二次燃焼用空気により二次燃焼させて完全燃焼させると共に、予熱通路内を通過する燃焼用空気を二次燃焼室内の高温の排ガスにより内筒を通して加熱するようにしている。即ち、本発明の排熱回収装置は、二次燃焼塔としての機能と空気予熱器としての機能を併せ持つ為、従来の溶融処理設備のように用途の異なる二次燃焼塔と空気予熱器を別個に設置すると云うこともなく、設置スペースを半減できて建設コストや設備コストの大幅な削減を図れる。
【0036】
また、本発明の請求項1の排熱回収装置は、上記効果に加えて更に次のような効果を奏することができる。即ち、排熱回収装置は、内筒が金属製の円筒の内周面に耐火物を内張りすることにより形成されている為、二次燃焼室内を流れる高温・高腐食性の排ガスやダストが金属部材である円筒に直接接触すると云うことがなく、内筒の腐食を防止することができる。又、耐火物を内張りすることによって、従来の空気予熱器のように排ガスの温度を内筒材質の最高使用温度以下となるように下げる必要もなく、高温排ガスからの熱回収が可能になると共に、従来の空気予熱器のように空気予熱器の手前で冷却空気を吹き込む必要もなくなり、排ガスの排出量が増大すると云うこともない。更に、内筒の内周面に内張りした耐火物からの熱伝導により予熱通路内を通過する燃焼用空気を加熱するようにしている為、排ガスと接触する耐火物の表面温度が著しく低下すると云うことがない。その結果、内筒の内周面付近を流れる排ガス中にダイオキシン類の再合成し易い温度域を作ることがなくなり、ダイオキシン類対策としての効果が得られる。そのうえ、二次燃焼室の上流側位置に二次燃焼用空気吹込みノズルを設け、当該二次燃焼用空気吹込みノズルから内筒の内周面に沿ってその接線方向に二次燃焼用空気を吹き込んで二次燃焼室内に旋回流を形成するようにしている為、排ガス中に含まれる未燃ガスは二次燃焼室内に於いて十分な滞留時間と温度をもって攪拌・燃焼される。その結果、表面溶融炉から排出される排ガス中の未燃ガスは完全燃焼されることになる。
加えて、本発明の請求項2の排熱回収装置は、内筒を多孔質性の耐火物により円筒状に形成し、予熱通路内を通過する燃焼用空気を耐火物からの熱伝導により加熱すると共に、予熱通路内の燃焼用空気の一部が二次燃焼用空気として多孔質性の耐火物の孔から二次燃焼室内へ流れ込むようにしている為、請求項1の排熱回収装置と同様の作用効果を奏することができるうえ、内筒内周面へのダストの付着を防止することができる。
また、請求項3の発明では、二次燃焼室の上流側位置に二次燃焼用空気吹込みノズルを設け、当該二次燃焼用空気吹込みノズルから内筒の内周面に沿ってその接線方向に二次燃焼用空気を吹き込んで二次燃焼室内に旋回流を形成するようにしている為、排ガス中に含まれる未燃ガスは二次燃焼室内に於いて十分な滞留時間と温度をもって攪拌・燃焼される。その結果、表面溶融炉から排出される排ガス中の未燃ガスは完全燃焼されることになる。
【図面の簡単な説明】
【図1】本発明の実施の形態に係る排熱回収装置を用いた溶融処理設備の概略系統図である。
【図2】本発明の実施の形態に係る排熱回収装置の概略縦断面図である。
【図3】同じく排熱回収装置の概略横断面図である。
【図4】本発明の他の実施の形態に係る排熱回収装置の概略縦断面図である。
【図5】表面溶融炉を用いた従来の溶融処理設備の概略系統図である。
【図6】従来の溶融処理設備に用いる空気予熱器の概略縦断面図である。
【符号の簡単な説明】
1は排熱回収装置、2は表面溶融炉、11は二次燃焼用吹込みノズル、24は内筒、24aは円筒、25は外筒、26・26′は耐火物、Gは排ガス、Sは二次燃焼室、S′は予熱通路、Aは燃焼用空気、A′は二次燃焼用空気。
[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is used in a melting treatment facility provided with a melting furnace for melting a substance to be melted such as incineration residue and fly ash discharged from a refuse incinerator or sewage sludge or crushed incombustible material. The present invention relates to an exhaust heat recovery device in a melting furnace having both a function as a secondary combustion tower for secondary combustion of exhaust gas discharged from a furnace and a function as an air preheater for recovering heat from high-temperature exhaust gas.
[0002]
[Prior art]
In recent years, in order to reduce the volume and harmlessness of incineration residues and fly ash (hereinafter referred to as “melted material”) discharged from refuse incinerators, a method of melting and solidifying the material to be melted has attracted attention, and it has actually been put to practical use. Have been. This is because by melting and solidifying the material to be melted, its volume can be reduced to 1/2 to 1/3, and it is physically and chemically stable to prevent elution of harmful substances such as heavy metals and dioxins. This makes it possible to completely disassemble, reuse as concrete filler materials, roadbed materials, blocks, etc., extend the life of the final landfill site, etc.
[0003]
Thus, in the method of melting and solidifying the material to be melted, an electric melting furnace such as an arc melting furnace, a plasma arc furnace, or an electric resistance furnace is used, and the material to be melted is melted by electric energy. Using a method of solidifying by water cooling or air cooling and a surface melting furnace, a swirling melting furnace, a combustion type melting furnace such as a coke bed furnace, and melting the material to be melted by the combustion energy of fossil fuel such as kerosene or natural gas, The method of solidifying this by water cooling or air cooling is often used, and when the power generation equipment is installed in the melting treatment facility for the material to be melted, the former method using electric energy, When not juxtaposed, the latter method using combustion energy is often adopted.
[0004]
FIG. 5 is a schematic system diagram showing an example of a melting treatment facility for a material to be melted using a surface melting furnace. In FIG. 5, reference numeral 40 denotes a surface melting furnace, 41 denotes a high-temperature flue, and 42 denotes a secondary combustion tower. , 43 is a secondary combustion air blowing nozzle, 44 is a secondary combustion air supply pipe, 45 is a secondary combustion air blower, 46 is a gas cooling blower, 47 is an air preheater, and 48 is a surface melting furnace. A combustion air supply pipe to the burner 62, 49 is a push-in blower, 50 is a gas cooling device, 51 is cooling water, 52 is a supply pipe for activated carbon, slaked lime and auxiliary, 53 is a dust collector, 54 is a fly ash conveyer. Reference numeral 55 denotes a catalytic denitration tower, reference numeral 56 denotes an induction ventilator, and reference numeral 57 denotes a chimney.
[0005]
The surface melting furnace 40 uses combustion heat of fossil fuel such as kerosene or natural gas as a heat source, and is provided with a material to be melted from four directions into the furnace to form a four-sided molten surface. The structure or the furnace has a face-to-face structure in which a material to be melted is supplied from two facing directions to form an inclined molten surface.
That is, as shown in FIG. 1, the surface melting furnace 40 includes a furnace body 58, hoppers 59 provided in four directions or two facing directions around the furnace body 58, and a material W to be distributed and charged into each hopper 59. A melt distributing / supplying device 60, a melt extruding device 61 for supplying the melt W supplied to each hopper 59 into the furnace, and one unit for heating and melting the melt W in the furnace from the front side or A plurality of burners 62, a slag tap 63 for discharging molten slag, a water-sealed slag conveyor 64 (or air-cooled slag conveyor) for granulating (or air cooling) and discharging molten slag flowing down from the slag tap 63, and the like. , And a secondary combustion tower 42 and an air preheater 47 are sequentially connected to the surface melting furnace 40 via a high-temperature flue 41.
[0006]
The secondary combustion tower 42 has a cylindrical refractory structure having a secondary combustion chamber S therein, and a secondary revolving section that gives a swirl into the secondary combustion chamber S is provided at a lower position of the secondary combustion tower 42. A combustion air blowing nozzle 43 is provided.
As shown in FIG. 6, the air preheater 47 has a double cylindrical structure in which an inner cylinder 65 and an outer cylinder 66 made of steel plates having different diameters are arranged concentrically. When the high temperature exhaust gas G flows, the combustion air A for the burner 62 flowing between the inner cylinder 65 and the outer cylinder 66 is heated. This air preheater 47 absorbs the thermal expansion between the inner cylinder 65 and the outer cylinder 66 caused by the temperature rise by the expansion joint 67.
[0007]
Thus, in the melting processing equipment, the melted material W such as incineration residues distributed and injected into the respective hoppers 59 by the melted material distribution and supply device 60 is moved into the furnace body 58 by the melted material extruding device 61. And is deposited on the furnace bottom in a state where the surface becomes a substantially mortar-shaped inclined surface centering on the slag tap 63, and is sequentially heated and melted from the surface side by the combustion heat of the burner 62, thereby melting the film. It becomes slag. The molten slag flows down a mortar-shaped inclined surface, falls from a slag tap 63 onto a water-sealed slag conveyor 64, is cooled and solidified by cooling water to form granulated slag, and then is cooled by a water-sealed slag conveyor 64. It is discharged by.
[0008]
On the other hand, the high-temperature combustion exhaust gas G in the furnace main body 58 is discharged from the slag tap 63 together with the molten slag, and is sent into the secondary combustion tower 42 through the high-temperature flue 41. The combustion exhaust gas G sent into the secondary combustion tower 42 is injected into the secondary combustion chamber S by the secondary combustion air A ′ blown into the secondary combustion chamber S from the secondary combustion air injection nozzle 43. Secondary combustion. Thereby, the unburned gas contained in the exhaust gas G is completely burned in the secondary combustion chamber S with a sufficient residence time and temperature.
The exhaust gas G that has been completely burned continues to enter the air preheater 47, where the combustion air A for the burner 62 sent from the forced blower 49 to the air preheater 47 is heated to about 350 ° C. After passing through the cooling device 50, the dust collecting device 53, the catalytic denitration tower 55, the draft ventilator 56 and the chimney 57, it is released as clean gas into the atmosphere.
[0009]
[Problems to be solved by the invention]
By the way, when the secondary combustion tower 42 and the air preheater 47 are installed as separate devices as in the above-mentioned melting processing equipment, there are the following problems (1) to (4).
{Circle around (1)} The secondary combustion tower 42 needs to have a sufficient size to completely burn unburned gas in the exhaust gas G, and the air preheater 47 also has a sufficient size to recover heat from the exhaust gas G. A heat transfer area is required, and the secondary combustion tower 42 and the air preheater 47 are both large devices. As a result, a space for separately installing the secondary combustion tower 42 and the air preheater 47 is inevitably large, and there is a problem that construction costs and equipment costs increase.
{Circle around (2)} Since the inner cylinder 65 of the air preheater 47 comes into direct contact with the exhaust gas G, the temperature of the exhaust gas G is set to around 650 ° C. so that the inner peripheral surface temperature of the inner cylinder 65 becomes lower than the maximum use temperature of the material of the inner cylinder 65. Need to be lowered to However, since the temperature of the exhaust gas near the outlet of the secondary combustion tower 42 is close to 900 ° C., cooling air or cooling water must be blown before the air preheater 47 to cool the exhaust gas G. The problem is that the amount increases.
{Circle around (3)} The secondary combustion tower 42 decomposes dioxins by completely burning the exhaust gas G at a high temperature of 850 ° C. or higher with a sufficient residence time, while the air preheater 47 degrades the dioxin between the inner cylinder 65 and the outer cylinder 66. However, there is a problem that a temperature range (around 300 ° C.) where dioxins are easily re-synthesized in the boundary layer of the exhaust gas G flowing near the inner peripheral surface of the inner cylinder 65 due to the temperature of the combustion air A flowing through the inner cylinder 65.
{Circle around (4)} In the exhaust gas G discharged from the surface melting furnace 40, HCl contained in the exhaust gas G is as high as several thousand ppm depending on the properties of the material to be melted W, and the inner peripheral surface of the inner cylinder 65 of the air preheater 47. Therefore, there is a problem that corrosion dust is caused on the inner peripheral surface of the inner cylinder 65 of the air preheater 47 because the molten dust mainly containing the molten salts adheres to the inner surface.
[0010]
The present invention has been made in view of such a problem, and its purpose is to integrate a secondary combustion tower and an air preheater that are installed as separate devices having different applications, thereby reducing the size of the equipment and reducing the size of the equipment. It is an object of the present invention to provide an exhaust heat recovery device in a melting furnace, which can reduce costs, prevent resynthesis of dioxins, and prevent corrosion due to exhaust gas.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present invention is to completely burn unburned gas in exhaust gas discharged from a melting furnace and to recover heat from the exhaust gas to heat combustion air. Heat recovery equipment in a molten furnaceIn the exhaust heat recovery device, combustion air is provided between an inner cylinder that forms a secondary combustion chamber into which exhaust gas from a melting furnace is fed and an outer peripheral surface of the inner cylinder that is disposed outside the inner cylinder. And an outer cylinder forming an annular preheating passage that passes therethrough.The unburned gas in the exhaust gas is subjected to secondary combustion in the secondary combustion chamber with secondary combustion air to complete combustion, and passes through the preheating passage. Heat recovery device in a melting furnace in which the combustion air to be heated is heated by the high temperature exhaust gas in the secondary combustion chamber through the inner cylinder, wherein the inner cylinder forming the secondary combustion chamber is formed of a metal cylinder. The inner cylinder is made of a refractory having excellent corrosion resistance and heat conductivity on the inner peripheral surface, and an air injection nozzle for secondary combustion is provided at a position upstream of the secondary combustion chamber to provide secondary combustion. Secondary combustion along the inner peripheral surface of the inner cylinder from the air blowing nozzle It is to that so as to form a swirling flow in the secondary combustion chamber by blowing air and the basic structure of the invention.
[0012]
The invention of claim 2 of the present inventionIn the exhaust heat recovery device in the melting furnace in which the unburned gas in the exhaust gas discharged from the melting furnace is completely burned and heat is recovered from the exhaust gas to heat the combustion air, The recovery device includes an inner cylinder forming a secondary combustion chamber into which exhaust gas from the melting furnace is fed, and an annular preheating passage through which combustion air passes between the inner cylinder and an outer peripheral surface of the inner cylinder. The secondary combustion chamber comprises an outer cylinder that forms unburned gas. The unburned gas in the exhaust gas is subjected to secondary combustion in the secondary combustion chamber with secondary combustion air to complete combustion, and the combustion air passing through the preheating passage is subjected to secondary combustion. An exhaust heat recovery device in a melting furnace in which a high temperature exhaust gas in a combustion chamber heats through an inner cylinder, wherein an inner cylinder forming a secondary combustion chamber is formed in a cylindrical shape from a porous refractory. The combustion air passing through the preheating passage from the refractory The basic structure of the invention is to heat by conduction and to allow a part of the combustion air in the preheating passage to flow into the secondary combustion chamber from the porous refractory hole as the secondary combustion air. It is.
[0013]
The invention of claim 3 of the present invention provides:A secondary combustion air blowing nozzle is provided at an upstream position of the secondary combustion chamber, and secondary combustion air is blown from the secondary combustion air blowing nozzle along the inner peripheral surface of the inner cylinder in a tangential direction thereof. Thus, a swirling flow is formed in the secondary combustion chamber.
[0014]
According to the invention of claim 4 of the present invention, the inner cylinder forming the secondary combustion chamber is formed in a cylindrical shape by a porous refractory, and the combustion air passing through the preheating passage is transferred by heat conduction from the refractory. In addition to the heating, a part of the combustion air in the preheating passage flows as secondary combustion air from the porous refractory hole into the secondary combustion chamber.
[0016]
The exhaust heat recovery apparatus 1 completely burns the unburned gas in the high-temperature combustion exhaust gas G that has passed through the high-temperature flue 10 from the surface melting furnace 2, and recovers heat from the exhaust gas G for the burner 7. It heats the combustion air A (or both the combustion air A for the burner 7 and the secondary combustion air A ') and has both a function as a conventional secondary combustion tower and a function as an air preheater. Things.
[0017]
That is, the exhaust heat recovery device 1 includes an inner cylinder 24 that forms a secondary combustion chamber S having a circular cross-sectional shape into which the high-temperature flue gas G that has passed through the high-temperature flue 10 is sent, and an outer periphery of the inner cylinder 24. An outer cylinder 25 that forms an annular preheating passage S ′ through which combustion air A for the burner 7 passes between the outer combustion surface A and the secondary combustion chamber B that blows the secondary combustion air A ′ into the secondary combustion chamber S The secondary combustion chamber S includes an air injection nozzle 11 and the like, and the unburned gas in the exhaust gas G is secondary-combusted by the secondary combustion air A 'in the secondary combustion chamber S and completely burned. The combustion air A for the burner 7 is heated by the exhaust gas G in the secondary combustion chamber S through the inner cylinder 24.
[0018]
Specifically, as shown in FIG. 2, the inner cylinder 24 is formed by lining a refractory 26 having excellent corrosion resistance and heat conductivity on the inner peripheral surface of a steel plate cylinder 24a. The refractory 26 has corrosion resistance to corrosive gas such as HCl and adhered dust mainly including molten salts such as NaCl and KCl, and has excellent thermal conductivity. And refractory bricks and other fixed refractories are used.
[0019]
As shown in FIG. 2, the outer cylinder 25 is formed of a steel plate into a cylindrical shape having a larger diameter than the inner cylinder 24, and is disposed concentrically around the outer periphery of the inner cylinder 24 to form an outer peripheral surface of the inner cylinder 24. And an annular preheating passage S 'through which the combustion air A for the burner 7 passes.
An inlet 27 for supplying fresh combustion air A to the preheating passage S 'is formed at the lower end of the outer cylinder 25, and the inlet 27 is connected to the push-in blower 15 via the combustion air supply pipe 14. Have been. An outlet 28 through which the combustion air A heated in the preheating passage S 'flows out is formed at the upper end of the outer cylinder 25, and the outlet 28 is connected to the burner 7 through the combustion air supply pipe 14. It is connected to the.
[0020]
The upper end of the inner cylinder 24 and the outer cylinder 25 are connected in an airtight manner, and the lower ends thereof are connected in an airtight manner via an expansion joint 29. The expansion joint 29 absorbs thermal expansion generated between the outer cylinder 25 and the outer cylinder 25.
[0021]
As shown in FIGS. 2 and 3, the secondary combustion air blowing nozzle 11 is provided at several positions upstream of the secondary combustion chamber S (lower position in FIG. 2). The secondary combustion air A 'is blown in the tangential direction along the inner peripheral surface of the secondary combustion chamber to form a swirling flow in the secondary combustion chamber S. The secondary combustion air blowing nozzle 11 is connected to a forced air blower 15 via a secondary combustion air supply pipe 12.
[0022]
The exhaust heat recovery device 1 has an upstream end (lower end in FIG. 2) connected to a high-temperature flue 10 through which high-temperature combustion exhaust gas G discharged from the surface melting furnace 2 flows. The downstream end (upper end in FIG. 2) is connected to the cooling device 16 so as to communicate with the exhaust gas G sent from the high-temperature flue 10 in the secondary combustion chamber S. After the secondary combustion by the secondary combustion air A ', the air is sent into the gas cooling device 16 and the combustion air A for the burner 7 flowing in the preheating passage S' is heated.
[0023]
Next, a case in which the material to be melted W such as incineration residues is melted using the melting processing equipment provided with the above-described exhaust heat recovery device 1 will be described.
The molten material W such as incineration residue discharged from the refuse incinerator is distributed and charged into each hopper 4 by the molten material distributing and supplying device 5, and then sequentially into the melting furnace main body 3 by the molten material extruding device 6. It is fed and deposited on the furnace bottom in a state where the surface is a substantially mortar-shaped inclined surface centering on the slag tap 8.
[0024]
The material to be melted W deposited on the furnace bottom is heated to a high temperature of 1300 ° C. to 1400 ° C. by the combustion flame from the burner 7 and is sequentially melted from the surface side to become a film-like molten slag. The molten slag flows down the mortar-shaped inclined surface, falls from the slag tap 8 onto the water-sealed slag conveyor 9, is cooled and solidified by the cooling water to form granulated slag, and then becomes the water-sealed slag conveyor 9. It is discharged by.
[0025]
As the molten slag flows down the inclined surface, new molten materials W are successively exposed on the inclined surface, and the exposed new molten materials W are successively formed into films by the combustion flame from the burner 7. Going to be melted.
When the melted inclined surface recedes with the progress of melting, the molten material extruding device 6 operates to push the new molten material W in the hopper 4 into the furnace. As a result, the melted inclined surface of the material W layer is maintained at an angle of repose or an angle close to the angle of repose of the material W to be melted. As a result, the molten slag that has been melted in the form of a film easily flows down the inclined surface, so that a new material to be melted W is immediately exposed, and the melting process is rapidly performed.
[0026]
On the other hand, the high-temperature combustion exhaust gas G generated in the furnace main body 3 is discharged from the slag tap 8 together with the molten slag, is sent to the exhaust heat recovery device 1 through the high-temperature flue 10, and is subjected to secondary combustion therein. As well as heat recovery.
That is, the combustion exhaust gas G sent into the secondary combustion chamber S of the exhaust heat recovery device 1 is generated by the secondary combustion air A ′ blown into the secondary combustion chamber S from the secondary combustion air blowing nozzle 11. Secondary combustion is performed in the secondary combustion chamber S. At this time, the secondary combustion air A 'is blown from the secondary combustion air blowing nozzle 11 along the inner peripheral surface of the inner cylinder 24 in the tangential direction to form a swirl flow in the secondary combustion chamber S. Therefore, the unburned gas contained in the exhaust gas G is stirred and burned in the secondary combustion chamber S with a sufficient residence time and temperature. As a result, the unburned gas in the exhaust gas G discharged from the surface melting furnace 2 is completely burned.
In addition, fresh combustion air A (temperature: about 20 ° C.) is fed into the preheating passage S ′ of the exhaust heat recovery device 1 from the forced air blower 15 and the combustion air supply pipe 14. The combustion air A flowing in the preheating passage S ′ is heated to about 350 ° C. by heat conduction from the refractory 26 forming the inner cylinder 24, and then supplied to the burner 7 through the combustion air supply pipe 14. It is used for combustion.
[0027]
Then, the exhaust gas G after the secondary combustion in the secondary combustion chamber S of the exhaust heat recovery device 1 is continuously sent to the gas cooling device 16, where the temperature is reduced to 200 ° C. or less by injection of the cooling water 17. After that, the gas passes through the dust collecting device 19, the catalytic denitration tower 21, the induction ventilator 22, and the chimney 23 and is released as clean gas into the atmosphere.
[0028]
As described above, the exhaust heat recovery device 1 has both a function as a secondary combustion tower and a function as an air preheater. Without separately installing the air preheater, the installation space can be halved and the construction cost and equipment cost can be significantly reduced.
Further, in the exhaust heat recovery device 1, since the inner cylinder 24 is formed by lining the refractory 26 on the inner peripheral surface of the metal cylinder 24 a, the high temperature and high corrosiveness flowing in the secondary combustion chamber S The exhaust gas G or dust does not directly contact the cylinder 24a, which is a metal member, so that corrosion of the inner cylinder 24 can be prevented. Needless to say, by lining the refractory material 26, there is no need to lower the temperature of the exhaust gas G to be lower than the maximum operating temperature of the inner cylinder material unlike the conventional air preheater. At the same time, it is not necessary to blow cooling air before the air preheater, and the amount of exhaust gas G discharged does not increase.
Further, the exhaust heat recovery device 1 heats the combustion air A of the burner 7 passing through the preheating passage S 'by heat conduction from the refractory 26 lining the inner peripheral surface of the inner cylinder 24. In addition, the surface temperature of the refractory 26 in contact with the exhaust gas G does not drop significantly. As a result, a temperature range (around 300 ° C.) where dioxins are easily re-synthesized is not created in the exhaust gas G flowing near the inner peripheral surface of the inner cylinder 24, and an effect as a measure against dioxins is obtained.
[0029]
FIG. 4 is a schematic cross-sectional view of an exhaust heat recovery apparatus 1 according to another embodiment of the present invention. The exhaust heat recovery apparatus 1 includes a high-temperature flue gas G that has passed through a high-temperature flue 10. And the like, which forms an annular preheating passage S 'through which combustion air A for the burner 7 passes between the inner cylinder 24 forming the secondary combustion chamber S into which the air is sent, and the outer peripheral surface of the inner cylinder 24. The inner cylinder 24 forming the secondary combustion chamber S is formed in a cylindrical shape by a porous refractory 26 ', and the combustion air A for the burner 7 passing through the preheating passage S' is refractory 26 ′, And a part of the combustion air A in the preheating passage S ′ flows into the secondary combustion chamber S from the hole of the porous refractory 26 ′ as the secondary combustion air A ′. It has become.
[0030]
The inner cylinder 24 is formed by stacking porous block-shaped refractories 26 'in a cylindrical shape, and each refractory 26' is supported by the outer cylinder 25 via a plurality of hooks 30 made of steel. Have been. That is, each refractory 26 ′ is formed by embedding one end of a steel hook 30 in each refractory 26 ′ and fixing the other end of the hook 30 to the inner peripheral surface of the outer cylinder 25 by welding or the like. It is supported by the outer cylinder 25. As the refractory 26 ', a refractory 26' having excellent heat conductivity and capable of allowing a part of the combustion air A flowing in the preheating passage S 'to flow into the secondary combustion chamber S is used. I have.
[0031]
The outer cylinder 25 is formed of a steel plate into a cylindrical shape having a larger diameter than the inner cylinder 24, is disposed concentrically around the outer periphery of the inner cylinder 24, and is disposed between the outer cylinder 25 and the outer peripheral surface of the inner cylinder 24. To form an annular preheating passage S 'through which the combustion air A passes.
An inlet 27 for supplying fresh combustion air A to the preheating passage S 'is formed at the lower end of the outer cylinder 25. The inlet 27 is connected to the push-in blower 15 through the combustion air A supply pipe 14. It is connected. An outlet 28 through which the combustion air A heated in the preheating passage S 'flows out is formed at the upper end of the outer cylinder 25, and the outlet 28 is connected to the burner 7 through the combustion air supply pipe 14. It is connected to the.
[0032]
The upper end of the inner cylinder 24 and the outer cylinder 25 are connected in an airtight manner, and the lower ends thereof are connected in an airtight manner via an expansion joint 29. The expansion joint 29 absorbs the thermal expansion generated between the outer cylinder 24 and the outer cylinder 25.
In FIG. 4, reference numeral 31 denotes a damper interposed in the combustion air supply pipe 14, and 32 denotes a damper so that the temperature and the flow rate of the combustion air A flowing in the combustion air supply pipe 14 become predetermined values. 31 is a controller that controls 31.
[0033]
Thus, in the exhaust heat recovery device 1, the heat of the combustion exhaust gas G sent into the secondary combustion chamber S of the exhaust heat recovery device 1 through the high-temperature flue 10 forms the inner cylinder 24. The combustion air A transmitted to the refractory 26 'and flowing in the preheating passage S' by heat conduction from the refractory 26 'is heated to about 350C. The heated combustion air A is supplied to the burner 7 through the combustion air supply pipe 14 and used for combustion.
A part of the combustion air A in the preheating passage S 'flows into the secondary combustion chamber S from the hole of the porous refractory 26', and is used as the secondary combustion air A '. As a result, the combustion exhaust gas G in the secondary combustion chamber S is subjected to secondary combustion in the secondary combustion chamber S by the secondary combustion air A ', and the unburned gas contained in the exhaust gas G is converted to the secondary combustion air. It is completely burned in the combustion chamber S. The exhaust gas G that has been completely burned is continuously sent to the gas cooling device 16, where the temperature of the exhaust gas G is reduced to 200 ° C. or less by injection of the cooling water 17, and then the dust collecting device 19, the catalytic denitration tower 21, the induction draft fan 22, It is released as clean gas through the chimney 23 into the atmosphere.
[0034]
The exhaust heat recovery device 1 can achieve the same operation and effect as the exhaust heat recovery device 1 shown in FIG. 2 described above. Naturally, the exhaust heat recovery apparatus 1 is a porous refractory in which a part of the combustion air A for the burner 7 flowing in the preheating passage S 'forms the inner cylinder 24 as the secondary combustion air A'. Since the gas flows from the inner peripheral surface of the inner cylinder 24 into the secondary combustion chamber S through the hole 26 ', dust can be prevented from adhering to the inner peripheral surface of the inner cylinder 24.
[0035]
【The invention's effect】
As described above, in the exhaust heat recovery apparatus of the first aspect of the present invention, the outer cylinder is disposed around the inner cylinder forming the secondary combustion chamber, and the combustion air passes between the inner cylinder and the outer cylinder. An annular preheating passage is formed, and the unburned gas in the exhaust gas is subjected to secondary combustion in the secondary combustion chamber with the secondary combustion air to complete combustion, and the combustion air passing through the preheating passage is subjected to secondary combustion. The hot exhaust gas in the combustion chamber is heated through the inner cylinder. That is, since the exhaust heat recovery device of the present invention has both the function as a secondary combustion tower and the function as an air preheater, the secondary combustion tower and the air preheater, which have different uses like conventional melting processing equipment, are separated. The installation space can be halved, and construction costs and equipment costs can be greatly reduced.
[0036]
Further, claim 1 of the present inventionThe exhaust heat recovery device of the present invention has the following effects in addition to the above effects.That is, the exhaust heat recovery device isSince the inner cylinder is formed by lining a refractory material on the inner peripheral surface of a metal cylinder, high-temperature and highly corrosive exhaust gas and dust flowing in the secondary combustion chamber come into direct contact with the metal cylinder. Without saying, corrosion of the inner cylinder can be prevented. Also, by lining the refractory, it is not necessary to lower the temperature of the exhaust gas to be lower than the maximum operating temperature of the inner cylinder material unlike a conventional air preheater, and heat recovery from high-temperature exhaust gas becomes possible. Further, unlike the conventional air preheater, there is no need to blow cooling air before the air preheater, and the amount of exhaust gas discharged does not increase. Furthermore, since the combustion air passing through the preheating passage is heated by heat conduction from the refractory lining the inner peripheral surface of the inner cylinder, the surface temperature of the refractory in contact with the exhaust gas is significantly reduced. Nothing. As a result, a temperature range in which dioxins are easily re-synthesized is not generated in exhaust gas flowing near the inner peripheral surface of the inner cylinder, and an effect as a measure against dioxins can be obtained.Besides,A secondary combustion air blowing nozzle is provided at an upstream position of the secondary combustion chamber, and secondary combustion air is blown from the secondary combustion air blowing nozzle along the inner peripheral surface of the inner cylinder in a tangential direction thereof. As a result, a swirling flow is formed in the secondary combustion chamber, so that the unburned gas contained in the exhaust gas is stirred and burned in the secondary combustion chamber with a sufficient residence time and temperature. As a result, the unburned gas in the exhaust gas discharged from the surface melting furnace is completely burned.
In addition, claim 2 of the present inventionIn the exhaust heat recovery device, the inner cylinder is formed in a cylindrical shape with a porous refractory, and the combustion air passing through the preheating passage is heated by heat conduction from the refractory, and the combustion air in the preheating passage is heated. Because part of the air flows into the secondary combustion chamber through the porous refractory holes as secondary combustion air,Claim 1The same operation and effect as those of the exhaust heat recovery device can be obtained, and the adhesion of dust to the inner peripheral surface of the inner cylinder can be prevented.
In the invention of claim 3,A secondary combustion air blowing nozzle is provided at an upstream position of the secondary combustion chamber, and secondary combustion air is blown from the secondary combustion air blowing nozzle along the inner peripheral surface of the inner cylinder in a tangential direction thereof. As a result, a swirling flow is formed in the secondary combustion chamber, so that the unburned gas contained in the exhaust gas is stirred and burned in the secondary combustion chamber with a sufficient residence time and temperature. As a result, the unburned gas in the exhaust gas discharged from the surface melting furnace is completely burned.
[Brief description of the drawings]
FIG. 1 is a schematic system diagram of a melting processing facility using an exhaust heat recovery device according to an embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of the exhaust heat recovery device according to the embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view of the exhaust heat recovery device.
FIG. 4 is a schematic longitudinal sectional view of an exhaust heat recovery device according to another embodiment of the present invention.
FIG. 5 is a schematic system diagram of a conventional melting processing facility using a surface melting furnace.
FIG. 6 is a schematic longitudinal sectional view of an air preheater used in a conventional melting processing facility.
[Brief description of reference numerals]
1 is an exhaust heat recovery device, 2 is a surface melting furnace, 11 is a secondary combustion blowing nozzle, 24 is an inner cylinder, 24a is a cylinder, 25 is an outer cylinder, 26 and 26 'are refractories, G is exhaust gas, S Is a secondary combustion chamber, S 'is a preheating passage, A is combustion air, and A' is secondary combustion air.

Claims (3)

  1. 溶融炉から排出された排ガス中の未燃ガスを完全燃焼させると共に、この排ガスから熱回収して燃焼用空気を加熱するようにした溶融炉に於ける排熱回収装置で於いて、当該排熱回収装置は、溶融炉からの排ガスが送り込まれる二次燃焼室を形成する内筒と、内筒の外側に配設されてその外周面との間に燃焼用空気が通過する環状の予熱通路を形成する外筒とから成り、排ガス中の未燃ガスを二次燃焼室内に於いて二次燃焼用空気により二次燃焼させて完全燃焼させると共に、予熱通路内を通過する燃焼用空気を二次燃焼室内の高温の排ガスにより内筒を通して加熱するようにした溶融炉に於ける排熱回収装置であって、二次燃焼室を形成する内筒を、金属製の円筒の内周面に耐食性及び熱伝導性に優れた耐火物を内張りして成る内筒とすると共に、二次燃焼室の上流側位置に二次燃焼用空気吹込みノズルを設け、当該二次燃焼用空気吹込みノズルから内筒の内周面に沿ってその接線方向に二次燃焼用空気を吹き込んで二次燃焼室内に旋回流を形成するようにしたことを特徴とする溶融炉に於ける排熱回収装置。The unburned gas in exhaust gas discharged from the melting furnace causes complete combustion, at exhaust heat recovery device in the melting furnace so as to heat the combustion air by heat recovery from the exhaust gas, the exhaust heat The recovery device includes an inner cylinder forming a secondary combustion chamber into which exhaust gas from the melting furnace is fed, and an annular preheating passage through which combustion air passes between the inner cylinder and an outer peripheral surface of the inner cylinder. The secondary combustion chamber comprises an outer cylinder that forms unburned gas. The unburned gas in the exhaust gas is subjected to secondary combustion in the secondary combustion chamber with secondary combustion air to complete combustion, and the combustion air passing through the preheating passage is subjected to secondary combustion. An exhaust heat recovery device in a melting furnace in which a high temperature exhaust gas in a combustion chamber heats through an inner cylinder, wherein an inner cylinder forming a secondary combustion chamber is provided with corrosion resistance and an inner peripheral surface of a metal cylinder. Inner cylinder lined with refractory with excellent thermal conductivity In both cases, a secondary combustion air injection nozzle is provided at an upstream position of the secondary combustion chamber, and the secondary combustion air is injected from the secondary combustion air injection nozzle in the tangential direction along the inner peripheral surface of the inner cylinder. Exhaust heat to form a swirl flow in the secondary combustion chamber .
  2. 溶融炉から排出された排ガス中の未燃ガスを完全燃焼させると共に、この排ガスから熱回収して燃焼用空気を加熱するようにした溶融炉に於ける排熱回収装置で於いて、当該排熱回収装置は、溶融炉からの排ガスが送り込まれる二次燃焼室を形成する内筒と、内筒の外側に配設されてその外周面との間に燃焼用空気が通過する環状の予熱通路を形成する外筒とから成り、排ガス中の未燃ガスを二次燃焼室内に於いて二次燃焼用空気により二次燃焼させて完全燃焼させると共に、予熱通路内を通過する燃焼用空気を二次燃焼室内の高温の排ガスにより内筒を通して加熱するようにした溶融炉に於ける排熱回収装置であって、二次燃焼室を形成する内筒を多孔質性の耐火物により円筒状に形成し、予熱通路内を通過する燃焼用空気を耐火物からの熱伝導により加熱すると共に、予熱通路内の燃焼用空気の一部が二次燃焼用空気として多孔質性の耐火物の孔から二次燃焼室内へ流れ込むようにしたことを特徴とする溶融炉に於ける排熱回収装置。The unburned gas in exhaust gas discharged from the melting furnace causes complete combustion, at exhaust heat recovery device in the melting furnace so as to heat the combustion air by heat recovery from the exhaust gas, the exhaust heat The recovery device includes an inner cylinder forming a secondary combustion chamber into which exhaust gas from the melting furnace is fed, and an annular preheating passage through which combustion air passes between the inner cylinder and an outer peripheral surface of the inner cylinder. The secondary combustion chamber comprises an outer cylinder that forms unburned gas. The unburned gas in the exhaust gas is subjected to secondary combustion in the secondary combustion chamber with secondary combustion air to complete combustion, and the combustion air passing through the preheating passage is subjected to secondary combustion. An exhaust heat recovery device in a melting furnace in which a high temperature exhaust gas in a combustion chamber heats through an inner cylinder, wherein an inner cylinder forming a secondary combustion chamber is formed in a cylindrical shape from a porous refractory. The combustion air passing through the preheating passage from the refractory While heating by conduction, at a melting furnace, characterized in that as part of the combustion air in the preheating passage flows from the pores of the porous refractory as secondary combustion air into the secondary combustion chamber Waste heat recovery equipment.
  3. 二次燃焼室の上流側位置に二次燃焼用空気吹込みノズルを設け、当該二次燃焼用空気吹込みノズルから内筒の内周面に沿ってその接線方向に二次燃焼用空気を吹き込んで二次燃焼室内に旋回流を形成するようにしたことを特徴とする請求項2に記載の溶融炉に於ける排熱回収装置。 A secondary combustion air blowing nozzle is provided at an upstream position of the secondary combustion chamber, and secondary combustion air is blown from the secondary combustion air blowing nozzle along the inner peripheral surface of the inner cylinder in a tangential direction thereof. 3. The exhaust heat recovery device in a melting furnace according to claim 2, wherein a swirling flow is formed in the secondary combustion chamber .
JP2000125690A 2000-04-26 2000-04-26 Exhaust heat recovery equipment in melting furnace Expired - Fee Related JP3564040B2 (en)

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KR101875751B1 (en) 2017-11-02 2018-08-02 주식회사 이화정공 Manufacturing device for glass beads

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KR101118169B1 (en) * 2011-08-29 2012-03-16 주식회사 제이텍 Air preheater for smelting furnace
KR101118170B1 (en) * 2011-08-29 2012-03-16 주식회사 제이텍 Smelting furnace fiting one-type combustion chamber and air preheater
US9618203B2 (en) * 2012-09-26 2017-04-11 L'Air Liquide Société Anonyme Pour L'Étude Et L'Eploitation Des Procedes Georges Claude Method and system for heat recovery from products of combustion and charge heating installation including the same

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