JP2004293840A - Combustion control method of fire grate garbage incinerator - Google Patents

Combustion control method of fire grate garbage incinerator Download PDF

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JP2004293840A
JP2004293840A JP2003084307A JP2003084307A JP2004293840A JP 2004293840 A JP2004293840 A JP 2004293840A JP 2003084307 A JP2003084307 A JP 2003084307A JP 2003084307 A JP2003084307 A JP 2003084307A JP 2004293840 A JP2004293840 A JP 2004293840A
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gas
combustion
exhaust gas
concentration
measuring
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Satoshi Fujii
聡 藤井
Manabu Kuroda
学 黒田
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JFE Engineering Corp
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JFE Engineering Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion control method of a fire grate garbage incinerator and the garbage incinerator capable of realizing the stable combustion of garbage on a grate even when the combustion is performed under a low air ratio, and reducing the CO concentration and NOx concentration in exhaust gas. <P>SOLUTION: The supply amounts of the air and the exhaust gas supplied into a gas mixing chamber as the air for secondary combustion, are adjusted on the basis of the difference between a gas temperature in the combustion chamber and a gas temperature in the gas mixing chamber, the oxygen concentration, the CO concentration and the NOx concentration in the exhaust gas. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、火格子式のごみ焼却炉の運転制御方法及びごみ焼却炉に関する。
【０００２】
【従来の技術】
一般に火格子式ごみ焼却炉の燃焼用空気としては、火格子下から供給される一次燃焼用空気と炉内に直接供給される二次燃焼用空気とに分けることができる。これらの燃焼用空気量の制御、及び、火格子の送り速度の調整を行うことでごみの安定燃焼を実現し、排ガス中のダイオキシン類や窒素酸化物の発生量の抑制、熱回収効率の向上を図っている。
【０００３】
前記炉内に供給される一次燃焼用空気と二次燃焼用空気の合計量は、ごみの燃焼に必要な理論空気量の１．７倍程度（空気比）であり、ごみの燃焼に対して燃焼用空気が過剰な状態で操業されている。これは、投入されるごみの発熱量に変動が大きいためである。このため、空気過剰な状態で燃焼された排ガスからの熱回収となるため、ボイラでの熱回収が効率的に行われないといった問題があった。また、ごみの燃焼によって発生する排ガス量が多くなるため、ごみ焼却プラントの下工程設備にある排ガス処理装置、誘引ブロワ等の設備も排ガス量に対応して大型の設備を必要としていた。
【０００４】
一方、最近では、ダイオキシン類の発生量を抑えるために、燃焼排ガスを高温化させることで完全燃焼させる技術として、供給する燃焼用空気量を減らし、過剰な空気を減らすことで排ガス温度を高温化する方法が用いられている。さらに、供給する燃焼用空気量を減らすことにより、排出される排ガス量が少なくなるため、下工程の排ガス処理設備等の負荷が低減できるとしている（例えば、特許文献１参照）。
【０００５】
しかし、燃料がごみであるため、燃焼用空気量が少ないと、ごみの乾燥、燃焼、灰化までの燃焼プロセスを安定に維持することが困難となる。このため、一次燃焼用空気に酸素を富化し燃焼用空気の酸素濃度を高くする方法や、炉から排出された排ガスを再度炉内に戻し循環させる方法で燃焼を安定化させる方法がある（例えば、特許文献２参照）。
【０００６】
また、他の方法として、燃焼に必要な燃焼用空気の量を減らし、下工程設備の負荷を軽減し、熱回収効率を向上させるために、昇温した高温空気をごみが燃焼している表面上に供給することで、燃焼用空気の合計量を減らし空気比１．３程度で完全燃焼を実現させようとする方法もある（例えば、特許文献３参照）。
【０００７】
【特許文献１】
特開平１０−３３２１２０号公報
【０００８】
【特許文献２】
特開２００２−２６７１３２号公報
【０００９】
【特許文献３】
特開２０００−１９９６２０号公報
【００１０】
【発明が解決しようとする課題】
ここで、空気比が低い状態で完全燃焼を実現させるために、酸素富化、排ガス循環、高温空気燃焼等の方法を用いる必要がある。しかし、火格子上のごみの発熱量は一定でないために、空気比が低い状態で完全燃焼を実現させることは非常に困難である。
【００１１】
本発明は上記問題点を解決するためになされたもので、低空気比下で燃焼を行う場合においても火格子上のごみの安定燃焼を実現でき、排ガス中のＣＯ濃度、ＮＯｘ濃度を低減することが可能な火格子式ごみ焼却炉の燃焼制御方法及びごみ焼却炉を提供することを目的とする。
【００１２】
【課題を解決するための手段】
本発明者らは、低空気比下で燃焼を行う場合においても火格子上のごみの安定燃焼を実現でき、排ガス中のＣＯ濃度、ＮＯｘ濃度を低減できるごみ焼却炉の燃焼制御方法について検討を行った。ここで、前記低空気比下で燃焼を行う場合とは、ごみの燃焼に必要な理論空気量に対して、１．２倍程度から１．５倍程度、通常は１．３倍程度の空気量でごみの固形分及び排ガス中の未燃成分の完全燃焼を行う場合をいう。
【００１３】
図１は、実際のごみ焼却炉において、燃焼室内のガス温度とガス混合室内のガス温度との差に対するボイラ出口における排ガス中のＣＯ濃度の特性を調べた結果を示した図である。図１に示すように、燃焼室内のガス温度とガス混合室内のガス温度との差が図中Ａの領域であれば、排ガス中のＣＯ濃度は低くなり、さらに、排ガス中の未燃成分が少なく、ダイオキシン類等の発生量も少ない状態となる。また、図中Ｂの領域では、ガス混合室内のガス温度が燃焼室内のガス温度よりも高く、ＣＯ濃度は高く、さらに、排ガス中の未燃成分が多く、ダイオキシン類の発生量も多い状態となる。図中Ｃの領域では、ガス混合室内のガス温度が燃焼室内のガス温度よりも低く、排ガス中の未燃成分は少ないが、残っている未燃成分がガス混合室内のガス温度が低いため完全燃焼が十分に行われずダイオキシン類の発生量が増加する可能性がある。
【００１４】
また、図２は、排ガス中のＯ２ 濃度と、排ガス中のＣＯ濃度、及び、ガス混合室内ガス温度との特性を調べた結果を示した図である。図２に示すように、排ガス中のＯ２ 濃度とＣＯ濃度の特性から、低空気比運転ではない従来の燃焼（図中白抜き部分）では、燃焼用空気量が過剰なため、排ガス中の酸素濃度が高く、燃焼に必要な酸素があってもガス混合室内のガス温度が低下するため、排ガス中の未燃成分が完全燃焼できない状態となり、排ガス中のＣＯ濃度が高くなる。それに対し、低空気比運転下（図中塗潰し部分）では、排ガス中の未燃成分が従来の燃焼よりも多く、燃焼に必要な酸素量が不足するため、排ガス中のＣＯ濃度及びガス混合室内ガス温度とも高くなる。
【００１５】
また、図３は、炉から排出された排ガスと空気とを混合した二次燃焼用空気中の酸素濃度と、排ガス中のＮＯｘ濃度との特性を調べた結果を示した図である。図３に示すように、排ガスを混合しない二次燃焼用空気（酸素濃度が２１％）に比べ、排ガスを混合した二次燃焼用空気を供給することで排ガス中のＮＯｘ濃度を低減できることがわかる（図中Ｄ）。
【００１６】
低空気比下で運転すると、ごみから発生する未燃成分は多くなる。このため、ごみ層表面から発生する未燃成分をごみ層上部で燃焼させ、残りの未燃成分は二次燃焼用空気によってガス混合室内にて完全燃焼させてから炉外に排出させるようにする。なお、低空気比運転を行うために、二次燃焼用空気においても従来の１／４程度の供給量としているため、ごみ層上部で排ガス中の未燃成分を極力燃焼させ、残りの未燃成分をガス混合室内で完全燃焼させる状態とすることが好ましい。
【００１７】
そのためには、燃焼室内ガス温度はガス混合室内ガス温度よりも同程度もしくは高い状態とする必要があり、このような状態とすることで図１に示すように、炉から排出されるＣＯ濃度が低くなる（図１中Ａの領域）。逆に、ガス混合室内ガス温度が、燃焼室内ガス温度よりも高い状態となると（図１中Ｂの領域）、ごみ層上部で未燃成分が燃焼しきれず、ガス混合室内での未燃成分の燃焼負荷が上がり、ガス混合室内で燃焼しきれない未燃成分が排出されることとなり排ガス中のＣＯ濃度が高くなる。一方、ガス混合室内ガス温度が、燃焼室内ガス温度よりも低い状態では、燃焼室内で未燃成分がすべて燃焼してしまうため、ガス混合室内での未燃成分が少なくガス混合室内のガス温度が低くなる（図１中Ｃの領域）。
【００１８】
本発明は以上のような検討に基づきなされたもので、以下のような特徴を有する火格子式ごみ焼却炉の燃焼制御方法及びごみ焼却炉である。
［１］火格子式ごみ焼却炉の燃焼制御方法であって、燃焼室内のガス温度とガス混合室内のガス温度との差、及び、排ガス中の酸素濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を調整することを特徴とする火格子式ごみ焼却炉の燃焼制御方法。
［２］火格子式ごみ焼却炉の燃焼制御方法であって、燃焼室内のガス温度とガス混合室内のガス温度との差、排ガス中の酸素濃度、及び、排ガス中のＣＯ濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を調整することを特徴とする火格子式ごみ焼却炉の燃焼制御方法。
［３］火格子式ごみ焼却炉の燃焼制御方法であって、燃焼室内のガス温度とガス混合室内のガス温度との差、排ガス中の酸素濃度、排ガス中のＣＯ濃度、及び、排ガス中のＮＯｘ濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を調整することを特徴とする火格子式ごみ焼却炉の燃焼制御方法。
［４］燃焼室内のガス温度を計測する手段と、ガス混合室内のガス温度を計測する手段と、排ガス中の酸素濃度を計測する手段と、前記燃焼室内のガス温度を計測する手段により計測された燃焼室内ガス温度と前記ガス混合室内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、及び、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置とを備えたことを特徴とする火格子式ごみ焼却炉。
［５］燃焼室内のガス温度を計測する手段と、ガス混合室内のガス温度を計測する手段と、排ガス中の酸素濃度を計測する手段と、排ガス中のＣＯ濃度を計測する手段と、前記燃焼室内のガス温度を計測する手段により計測された燃焼室内ガス温度と前記ガス混合室内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度、及び、前記排ガス中のＣＯ濃度を計測する手段により計測されたＣＯ濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置とを備えたことを特徴とする火格子式ごみ焼却炉。
［６］燃焼室内のガス温度を計測する手段と、ガス混合室内のガス温度を計測する手段と、排ガス中の酸素濃度を計測する手段と、排ガス中のＣＯ濃度を計測する手段と、排ガス中のＮＯｘ濃度を計測する手段と、前記燃焼室内のガス温度を計測する手段により計測された燃焼室内ガス温度と前記ガス混合室内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度、前記排ガス中のＣＯ濃度を計測する手段により計測されたＣＯ濃度、及び、前記排ガス中のＮＯｘ濃度を計測する手段により計測されたＮＯｘ濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置とを備えたことを特徴とする火格子式ごみ焼却炉。
【００１９】
【発明の実施の形態】
図４は、本発明に係るごみ焼却炉の一実施形態を示す概略構成図である。
【００２０】
図４に示すごみ焼却炉は、火格子４を有する全連型（２４時間連続運転）の火格子式ごみ焼却炉であり、ホッパ１、燃焼室２、燃焼室２の出口側に設けられたガス混合室３、ガス混合室３の下流側に設置されたボイラ７を備えている。
【００２１】
クレーンでホッパ１に投入されたごみは、給塵装置５によって燃焼室２内の火格子４上に送り込まれる。火格子４は往復運動し、その往復運動によってごみの撹拌および移動が行われる。火格子４下をごみ搬送方向に４つの領域に分割した風箱（上流側からＮｏ．１，Ｎｏ．２，Ｎｏ．３，Ｎｏ．４）から燃焼室２内に一次燃焼用空気が供給される。燃焼室２内に供給された火格子上のごみは、火格子４上を移動しながら、火格子４下から供給される一次燃焼用空気によって、乾燥、燃焼、後燃焼が行われ灰となり、灰落下口６より外部に排出される。
【００２２】
一次燃焼用空気は、一次燃焼用空気ブロア８により各風箱を介して火格子４の下から燃焼室２内に供給される。また、各風箱に供給される一次燃焼用空気の量は、各風箱に一次燃焼用空気を供給する各配管に設けられた火格子下一次燃焼用空気ダンパ９ａ，９ｂ，９ｃ，９ｄにより調整される。なお、図４に示した例では、火格子４の下をごみ搬送方向に対し４つの風箱（Ｎｏ．１からＮｏ．４）で分割して一次燃焼用空気を供給する構成としているが、ごみ焼却炉の規模及び目的に応じて適宜変更可能であり４つの風箱の場合に限られるものではないことは言うまでもない。
【００２３】
また、燃焼室２内の火格子４上のごみが燃焼している表面上には、灯油等の燃料を燃焼させることによって加熱した高温空気とボイラ７出口から排出される排ガスを混合した空気が供給され、ごみ層から発生した未燃ガスを燃焼させる。
【００２４】
さらに、ガス混合室３内には、二次燃焼用空気ブロア１０からの二次燃焼用空気と、ボイラ７出口から排出される排ガスが供給され、燃焼室２内で燃焼しきれなかった燃焼排ガス中の未燃ガスを完全燃焼させる。ガス混合室３内で二次燃焼させた後の燃焼排ガスは、下流側のボイラ７で熱エネルギーを回収された後に外部に排出される。
【００２５】
ここで、燃焼室２内には図４に示すように中間天井１７を設けることが好ましい。中間天井１７を燃焼室内に設けることにより、燃焼室内のガスを火格子４の上流側のごみ乾燥過程で発生した可燃性ガスと下流側の後燃焼過程で発生した燃焼排ガスに２分して排出することができる。この２分して排出したガスをガス混合室３で再合流させることにより、ガス混合室３内でのガスの攪拌混合がさらに促進され、ガス混合室３内での燃焼がより安定化し、燃焼過程におけるダイオキシン類の発生のさらなる抑制、ごみ未燃の発生防止を図ることができる。なお、中間天井１７を有さないごみ焼却炉においても本発明が適用でいることは言うまでもない。
【００２６】
上記構成のごみ焼却炉において、本発明にかかるごみ焼却炉の第一の実施形態は、燃焼室２内のガス温度を計測する手段と、ガス混合室３内のガス温度を計測する手段と、排ガス中の酸素濃度を計測する手段と、前記燃焼室２内のガス温度を計測する手段により計測された燃焼室２内ガス温度と前記ガス混合室３内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、及び、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置１１とを備えたものである。
【００２７】
ここで、前記燃焼室２内のガス温度を計測する手段としては、例えば、燃焼室２内に設置された燃焼室内ガス温度計１２を用いることができる。また、前記ガス混合室３内のガス温度を計測する手段としては、例えば、ガス混合室３内に設置されたガス混合室内ガス温度計１３を用いることができる。また、前記排ガス中の酸素濃度を計測する手段としては、例えば、ボイラ７出口に設置された酸素濃度計１４を用いることができる。
【００２８】
前記燃焼制御装置１１は、前記燃焼室内ガス温度計１２により計測された燃焼室内ガス温度と前記ガス混合室内ガス温度計１３により計測されたガス混合室内ガス温度と前記酸素濃度計１４により計測された排ガス中酸素濃度とを取り込む手段と、前記燃焼室内ガス温度とガス混合室内ガス温度とを比較する手段と、前記燃焼室内ガス温度とガス混合室内ガス温度との比較結果及び排ガス中酸素濃度に基づいて二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する手段とを備えている。なお、燃焼制御装置１１には例えばコンピュータを使用することができる。
【００２９】
前記二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量の制御は、図２に示すように、ガス混合室内ガス温度が高い状態では、排ガス中の酸素濃度が低く、酸素不足により、ＣＯ濃度が高くなる。このため、ガス混合室内ガス温度が燃焼室内ガス温度よりも高い状態や酸素濃度が低い状態では、二次燃焼用空気中の空気の割合を増やして、ＣＯ等の未燃成分を燃焼させてその発生を抑制する。
【００３０】
具体的な調整方法としては、ガス混合室３内ガス温度が燃焼室２内ガス温度よりも高い場合に、二次燃焼用空気中の空気の割合を増やし、ガス混合室３内での二次燃焼用空気中の酸素濃度を高くし、ＣＯの発生を抑える。もしくは、ガス混合室３内の酸素濃度が低い状態の場合にＣＯ濃度が高くなるので、ガス混合室３内での二次燃焼用空気中の酸素濃度を高くする。この二次燃焼用空気中の空気割合の制御は、例えば、以下の表１に示すようなファジィルールを計算機上に構築し、燃焼制御装置１１内に組み込むことにより行うことができる。前記ファジィルールは、例えばｍｉｎ−ｍａｘ法、シングルトン法などを用い、後件部の二次燃焼用空気中の空気割合を決定する。
【００３１】
【表１】

Figure 2004293840
【００３２】
また、本発明にかかるごみ焼却炉の第二の実施形態は、燃焼室２内のガス温度を計測する手段と、ガス混合室３内のガス温度を計測する手段と、排ガス中の酸素濃度を計測する手段と、排ガス中のＣＯ濃度を計測する手段と、前記燃焼室２内のガス温度を計測する手段により計測された燃焼室２内ガス温度と前記ガス混合室３内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度、及び、前記排ガス中のＣＯ濃度を計測する手段により計測されたＣＯ濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置１１とを備えたものである。
【００３３】
ここで、前記燃焼室２内のガス温度を計測する手段としては、例えば、燃焼室２内に設置された燃焼室内ガス温度計１２を用いることができる。また、前記ガス混合室３内のガス温度を計測する手段としては、例えば、ガス混合室３内に設置されたガス混合室内ガス温度計１３を用いることができる。また、前記排ガス中の酸素濃度を計測する手段としては、例えば、ボイラ７出口に設置された酸素濃度計１４を用いることができる。また、前記排ガス中のＣＯ濃度を計測する手段としては、例えば、ボイラ７出口に設置されたＣＯ濃度計１５を用いることができる。
【００３４】
前記燃焼制御装置１１は、前記燃焼室内ガス温度計１２により計測された燃焼室内ガス温度と前記ガス混合室内ガス温度計１３により計測されたガス混合室内ガス温度と前記酸素濃度計１４により計測された排ガス中酸素濃度と前記ＣＯ濃度計１５により計測された排ガス中ＣＯ濃度とを取り込む手段と、前記燃焼室内ガス温度とガス混合室内ガス温度とを比較する手段と、前記燃焼室内ガス温度とガス混合室内ガス温度との比較結果、排ガス中の酸素濃度、及び、排ガス中ＣＯ濃度に基づいて二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する手段とを備えている。なお、燃焼制御装置１１には例えばコンピュータを使用することができる。
【００３５】
前記二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量の制御は、図２に示すように、ガス混合室内ガス温度が高い状態では、排ガス中の酸素濃度が低く、酸素不足により、ＣＯ濃度が高くなる。このため、ガス混合室内ガス温度が燃焼室内ガス温度よりも高い状態や酸素濃度が低い状態、もしくはＣＯ濃度が高い状態では、二次燃焼用空気中の空気の割合を増やして、ＣＯ等の未燃成分を燃焼させてその発生を抑制する。
【００３６】
具体的な調整方法としては、上述の第一の実施形態で示したファジィルールに加え、排ガス中のＣＯ濃度を直接計測し、排ガス中のＣＯ濃度が高いときに、二次燃焼用空気中の排ガス分を減らして空気を増やし、酸素濃度を高くし、ＣＯ濃度を低減するように調整する。同様に、二次燃焼用空気中の空気割合の制御は、以下の表２に示すようなファジィルールを計算機上に構築し、燃焼制御装置１１内に組み込むことにより行うことができる。前記ファジィルールは、例えばｍｉｎ−ｍａｘ法、シングルトン法などを用い、後件部の二次燃焼用空気中の空気割合を決定する。
【００３７】
【表２】
Figure 2004293840
【００３８】
また、本発明にかかるごみ焼却炉の第三の実施形態は、燃焼室２内のガス温度を計測する手段と、ガス混合室３内のガス温度を計測する手段と、排ガス中の酸素濃度を計測する手段と、排ガス中のＣＯ濃度を計測する手段と、排ガス中のＮＯｘ濃度を計測する手段と、前記燃焼室２内のガス温度を計測する手段により計測された燃焼室２内ガス温度と前記ガス混合室３内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度、前記排ガス中のＣＯ濃度を計測する手段により計測されたＣＯ濃度、及び、前記排ガス中のＮＯｘ濃度を計測する手段により計測されたＮＯｘ濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置１１とを備えたものである。
【００３９】
ここで、前記燃焼室２内のガス温度を計測する手段としては、例えば、燃焼室２内に設置された燃焼室内ガス温度計１２を用いることができる。また、前記ガス混合室３内のガス温度を計測する手段としては、例えば、ガス混合室３内に設置されたガス混合室内ガス温度計１３を用いることができる。また、前記排ガス中の酸素濃度を計測する手段としては、例えば、ボイラ７出口に設置された酸素濃度計１４を用いることができる。また、前記排ガス中のＣＯ濃度を計測する手段としては、例えば、ボイラ７出口に設置されたＣＯ濃度計１５を用いることができる。また、前記排ガス中のＮＯｘ濃度を計測する手段としては、例えば、ボイラ７出口に設置されたＮＯｘ濃度計１６を用いることができる。
【００４０】
前記燃焼制御装置１１は、前記燃焼室内ガス温度計１２により計測された燃焼室内ガス温度と前記ガス混合室内ガス温度計１３により計測されたガス混合室内ガス温度と前記酸素濃度計１４により計測された排ガス中酸素濃度と前記ＣＯ濃度計１５により計測された排ガス中ＣＯ濃度と前記ＮＯｘ濃度計１６により計測された排ガス中ＮＯｘ濃度とを取り込む手段と、前記燃焼室内ガス温度とガス混合室内ガス温度とを比較する手段と、前記燃焼室内ガス温度とガス混合室内ガス温度との比較結果、排ガス中の酸素濃度、排ガス中ＣＯ濃度、及び、排ガス中ＮＯｘ濃度に基づいて二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する手段とを備えている。なお、燃焼制御装置１１には例えばコンピュータを使用することができる。
【００４１】
前記二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量の制御は、図２に示すように、ガス混合室内ガス温度が高い状態では、排ガス中の酸素濃度が低く、酸素不足により、ＣＯ濃度が高くなる。このため、ガス混合室内ガス温度が燃焼室内ガス温度よりも高い状態や酸素濃度が低い状態、もしくはＣＯ濃度が高い状態では、二次燃焼用空気中の空気の割合を増やして、ＣＯ等の未燃成分を燃焼させてその発生を抑制する。また、図３に示すように、二次燃焼用空気中の空気の割合を減らせば、排ガス中のＮＯｘ濃度を低減することができるため、二次燃焼用空気流の空気の割合を排ガス温度や成分に基づいて総合的に調整することで、排ガス中のＣＯ、ＮＯｘ濃度を同時に低減することができる。
【００４２】
具体的な調整方法としては、上述の第二の実施形態で示したファジィルールに加え、排ガス中のＮＯｘ濃度を計測し、ＮＯｘ濃度が高く、ＣＯ濃度が低ければ、二次燃焼用空気中の空気量の割合を減らして酸素濃度を低くし、ＮＯｘ濃度を低減するファジィルールを追加する。同様に、二次燃焼用空気中の空気割合の制御は、以下の表３に示すようなファジィルールを計算機上に構築し、燃焼制御装置１１内に組み込むことにより行うことができる。前記ファジィルールは、例えばｍｉｎ−ｍａｘ法、シングルトン法などを用い、後件部の二次燃焼用空気中の空気割合を決定する。
【００４３】
【表３】
Figure 2004293840
【００４４】
【発明の効果】
以上説明したように本発明によれば、低空気比下で燃焼を行う場合においても火格子上のごみの安定燃焼を実現でき、排ガス中のＣＯ濃度、ＮＯｘ濃度を低減することが可能な火格子式ごみ焼却炉の燃焼制御方法及びごみ焼却炉が提供される。
【図面の簡単な説明】
【図１】実際のごみ焼却炉において、燃焼室内のガス温度とガス混合室内のガス温度との差に対するボイラ出口における排ガス中のＣＯ濃度の特性を調べた結果を示した図である。
【図２】排ガス中のＯ２ 濃度と、排ガス中のＣＯ濃度、及び、ガス混合室内ガス温度との特性を調べた結果を示した図である。
【図３】炉から排出された排ガスと空気とを混合した二次燃焼用空気中の酸素濃度と、排ガス中のＮＯｘ濃度との特性を調べた結果を示した図である。
【図４】本発明に係るごみ焼却炉の一実施形態を示す概略構成図である。
【符号の説明】
１ ホッパ
２ 燃焼室
３ ガス混合室
４ 火格子
５ 給塵装置
６ 灰落下口
７ ボイラ
８ 一次燃焼用空気ブロア
９ａ，９ｂ，９ｃ，９ｄ 火格子下一次燃焼用空気ダンパ
１０ 二次燃焼用空気ブロア
１１ 燃焼制御装置
１２ 燃焼室内ガス温度計
１３ ガス混合室内ガス温度計
１４ 酸素濃度計
１５ ＣＯ濃度計
１６ ＮＯｘ濃度計
１７ 中間天井[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a grate-type incinerator operation control method and an incinerator.
[0002]
[Prior art]
Generally, air for combustion in a grate-type incinerator can be divided into primary combustion air supplied from below the grate and secondary combustion air supplied directly into the furnace. By controlling the amount of combustion air and adjusting the feed rate of the grate, stable combustion of garbage is realized, the amount of dioxins and nitrogen oxides in exhaust gas is reduced, and the efficiency of heat recovery is improved. I am planning.
[0003]
The total amount of the primary combustion air and the secondary combustion air supplied into the furnace is about 1.7 times (air ratio) the theoretical air amount required for refuse combustion, and Operating with excess combustion air. This is because the calorific value of the input garbage varies greatly. For this reason, heat is recovered from exhaust gas burned in an excess air state, and there is a problem that heat recovery in the boiler is not performed efficiently. In addition, since the amount of exhaust gas generated by the combustion of the refuse increases, the facilities such as the exhaust gas treatment device and the induction blower in the downstream process equipment of the refuse incineration plant also require large-scale equipment corresponding to the amount of the exhaust gas.
[0004]
On the other hand, recently, in order to suppress the generation of dioxins, as a technology to complete combustion by raising the combustion exhaust gas, the amount of combustion air to be supplied is reduced and the temperature of the exhaust gas is raised by reducing excess air. Is used. Furthermore, since the amount of combustion air to be supplied is reduced by reducing the amount of combustion air to be supplied, the amount of exhaust gas discharged is reduced, so that the load on an exhaust gas treatment facility or the like in a downstream process can be reduced (for example, see Patent Document 1).
[0005]
However, since the fuel is refuse, if the amount of combustion air is small, it becomes difficult to stably maintain a combustion process from drying, burning, and incineration of the refuse. For this reason, there are a method of enriching oxygen in the primary combustion air to increase the oxygen concentration of the combustion air, and a method of stabilizing combustion by a method of returning exhaust gas discharged from the furnace to the furnace again and circulating it (for example, , Patent Document 2).
[0006]
Another method is to reduce the amount of combustion air required for combustion, reduce the load on downstream equipment, and improve the heat recovery efficiency. There is also a method in which the total amount of combustion air is reduced to achieve complete combustion at an air ratio of about 1.3 by supplying the air above (for example, see Patent Document 3).
[0007]
[Patent Document 1]
JP-A-10-332120
[Patent Document 2]
JP 2002-267132 A
[Patent Document 3]
Japanese Patent Application Laid-Open No. 2000-199620
[Problems to be solved by the invention]
Here, in order to realize complete combustion at a low air ratio, it is necessary to use a method such as oxygen enrichment, exhaust gas circulation, and high-temperature air combustion. However, since the calorific value of the refuse on the grate is not constant, it is very difficult to realize complete combustion at a low air ratio.
[0011]
The present invention has been made to solve the above problems, and can realize stable combustion of refuse on a grate even when performing combustion under a low air ratio, and reduce CO concentration and NOx concentration in exhaust gas. It is an object of the present invention to provide a grate-type incinerator combustion control method and a refuse incinerator capable of performing the above.
[0012]
[Means for Solving the Problems]
The present inventors have studied a combustion control method for a refuse incinerator that can realize stable combustion of refuse on a grate and reduce CO and NOx concentrations in exhaust gas even when combustion is performed at a low air ratio. went. Here, the case where the combustion is performed under the low air ratio means that the air is about 1.2 to 1.5 times, usually about 1.3 times, the theoretical amount of air required for refuse combustion. It refers to the case where the solid content of the refuse and the unburned components in the exhaust gas are completely burned by the amount.
[0013]
FIG. 1 is a diagram showing the results of examining the characteristics of the CO concentration in the exhaust gas at the boiler outlet with respect to the difference between the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber in an actual refuse incinerator. As shown in FIG. 1, if the difference between the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber is in the region A in the figure, the CO concentration in the exhaust gas is low, and the unburned component in the exhaust gas is low. Thus, the amount of dioxins generated is small. In the region B in the figure, the gas temperature in the gas mixing chamber is higher than the gas temperature in the combustion chamber, the CO concentration is high, the amount of unburned components in the exhaust gas is large, and the amount of dioxins generated is large. Become. In the region C in the figure, the gas temperature in the gas mixing chamber is lower than the gas temperature in the combustion chamber, and the unburned components in the exhaust gas are small, but the remaining unburned components are low because the gas temperature in the gas mixing chamber is low. There is a possibility that the amount of dioxins generated increases due to insufficient combustion.
[0014]
FIG. 2 is a diagram showing the results of examining the characteristics of the O 2 concentration in the exhaust gas, the CO concentration in the exhaust gas, and the gas temperature in the gas mixing chamber. As shown in FIG. 2, from the characteristics of the O 2 concentration and the CO concentration in the exhaust gas, in the conventional combustion that is not operated at a low air ratio (open area in the figure), the amount of combustion air is excessive, Even if the oxygen concentration is high and there is oxygen required for combustion, the gas temperature in the gas mixing chamber decreases, so that the unburned components in the exhaust gas cannot be completely burned, and the CO concentration in the exhaust gas increases. On the other hand, under the low air ratio operation (the painted area in the figure), the unburned components in the exhaust gas are larger than in the conventional combustion, and the amount of oxygen required for combustion is insufficient, so the CO concentration in the exhaust gas and the gas mixing chamber The gas temperature also increases.
[0015]
FIG. 3 is a graph showing the results of examining the characteristics of the oxygen concentration in the secondary combustion air obtained by mixing the exhaust gas discharged from the furnace with the air, and the NOx concentration in the exhaust gas. As shown in FIG. 3, it can be seen that the NOx concentration in the exhaust gas can be reduced by supplying the secondary combustion air mixed with the exhaust gas as compared with the secondary combustion air without mixing the exhaust gas (oxygen concentration is 21%). (D in the figure).
[0016]
When operated at a low air ratio, the unburned components generated from the refuse increase. Therefore, the unburned components generated from the surface of the refuse layer are burned in the upper portion of the refuse layer, and the remaining unburned components are completely burned in the gas mixing chamber by the secondary combustion air and then discharged out of the furnace. . In order to perform the low air ratio operation, the supply amount of the secondary combustion air is also reduced to about 1/4 of the conventional supply amount. Preferably, the components are completely burned in the gas mixing chamber.
[0017]
For this purpose, the temperature of the gas in the combustion chamber must be equal to or higher than the temperature of the gas in the gas mixing chamber. In such a state, the CO concentration discharged from the furnace is reduced as shown in FIG. (A in FIG. 1). Conversely, when the gas temperature in the gas mixing chamber becomes higher than the gas temperature in the combustion chamber (area B in FIG. 1), the unburned components cannot be completely burned in the upper part of the refuse layer, and The combustion load increases, and unburned components that cannot be completely burned in the gas mixing chamber are discharged, and the CO concentration in the exhaust gas increases. On the other hand, when the gas temperature in the gas mixing chamber is lower than the gas temperature in the combustion chamber, all unburned components are burned in the combustion chamber. (Area C in FIG. 1).
[0018]
The present invention has been made based on the above study, and is a combustion control method and a refuse incinerator for a grate refuse incinerator having the following features.
[1] A combustion control method for a grate-type refuse incinerator, which is used as secondary combustion air based on a difference between a gas temperature in a combustion chamber and a gas temperature in a gas mixing chamber and an oxygen concentration in exhaust gas. A combustion control method for a grate-type refuse incinerator, characterized by adjusting supply amounts of air and exhaust gas supplied into a gas mixing chamber.
[2] A combustion control method for a grate-type incinerator, comprising: a difference between a gas temperature in a combustion chamber and a gas temperature in a gas mixing chamber; an oxygen concentration in exhaust gas; and a CO concentration in exhaust gas. A combustion control method for a grate-type incinerator, comprising adjusting the supply amounts of air and exhaust gas supplied into a gas mixing chamber as secondary combustion air.
[3] A combustion control method for a grate-type incinerator, comprising: a difference between a gas temperature in a combustion chamber and a gas temperature in a gas mixing chamber; an oxygen concentration in exhaust gas; a CO concentration in exhaust gas; A combustion control method for a grate refuse incinerator, comprising: adjusting supply amounts of air and exhaust gas supplied into a gas mixing chamber as secondary combustion air based on a NOx concentration.
[4] Measured by means for measuring the gas temperature in the combustion chamber, means for measuring the gas temperature in the gas mixing chamber, means for measuring the oxygen concentration in the exhaust gas, and means for measuring the gas temperature in the combustion chamber. The difference between the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber measured by the means for measuring the gas temperature in the gas mixing chamber, and the oxygen concentration measured by the means for measuring the oxygen concentration in the exhaust gas. A grate-type incinerator, comprising: a combustion control device for controlling supply amounts of air and exhaust gas supplied to the gas mixing chamber as secondary combustion air.
[5] means for measuring the gas temperature in the combustion chamber, means for measuring the gas temperature in the gas mixing chamber, means for measuring the oxygen concentration in the exhaust gas, means for measuring the CO concentration in the exhaust gas, and The difference between the gas temperature in the combustion chamber measured by the means for measuring the gas temperature in the chamber and the gas temperature in the gas mixing chamber measured by the means for measuring the gas temperature in the gas mixing chamber, and the oxygen concentration in the exhaust gas are measured. Based on the oxygen concentration measured by the means, and the CO concentration measured by the means for measuring the CO concentration in the exhaust gas, the supply amounts of the air and the exhaust gas supplied into the gas mixing chamber as the secondary combustion air are determined. A grate-type incinerator, comprising: a combustion control device for controlling.
[6] means for measuring the gas temperature in the combustion chamber, means for measuring the gas temperature in the gas mixing chamber, means for measuring the oxygen concentration in the exhaust gas, means for measuring the CO concentration in the exhaust gas, and Means for measuring the NOx concentration of the gas in the combustion chamber and the gas temperature in the combustion chamber measured by the means for measuring the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber measured by the means for measuring the gas temperature in the gas mixing chamber. The difference, the oxygen concentration measured by the means for measuring the oxygen concentration in the exhaust gas, the CO concentration measured by the means for measuring the CO concentration in the exhaust gas, and the NO concentration measured by the means for measuring the NOx concentration in the exhaust gas A combustion control device that controls the supply amount of air and exhaust gas supplied into the gas mixing chamber as secondary combustion air based on the determined NOx concentration. Child-type refuse incinerator.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 4 is a schematic configuration diagram showing one embodiment of the refuse incinerator according to the present invention.
[0020]
The refuse incinerator shown in FIG. 4 is a continuous (24 hours continuous operation) grate type refuse incinerator having a grate 4 and is provided on the hopper 1, the combustion chamber 2, and the exit side of the combustion chamber 2. A gas mixing chamber 3 and a boiler 7 installed downstream of the gas mixing chamber 3 are provided.
[0021]
The dust put into the hopper 1 by the crane is sent to the grate 4 in the combustion chamber 2 by the dust supply device 5. The grate 4 reciprocates, and the agitating and moving of the refuse are performed by the reciprocating motion. Air for primary combustion is supplied into the combustion chamber 2 from a wind box (No. 1, No. 2, No. 3, No. 4 from the upstream side) divided below the grate 4 into four regions in the dust transport direction. You. The refuse on the grate supplied into the combustion chamber 2 is dried, burned, and post-combusted by the primary combustion air supplied from below the grate 4 while moving on the grate 4 to form ash. It is discharged to the outside from the ash drop 6.
[0022]
The primary combustion air is supplied into the combustion chamber 2 from below the grate 4 through each wind box by the primary combustion air blower 8. The amount of primary combustion air supplied to each wind box is determined by primary-combustion air dampers 9a, 9b, 9c, 9d below the grate provided in each pipe for supplying the primary combustion air to each wind box. Adjusted. In the example shown in FIG. 4, the primary combustion air is supplied by dividing the area under the grate 4 with four wind boxes (No. 1 to No. 4) in the dust transport direction. Needless to say, it can be appropriately changed according to the scale and purpose of the refuse incinerator and is not limited to the case of four wind boxes.
[0023]
On the surface of the grate 4 in the combustion chamber 2 where the refuse is burning, air mixed with high-temperature air heated by burning fuel such as kerosene and exhaust gas discharged from the outlet of the boiler 7 is provided. The supplied unburned gas generated from the refuse layer is burned.
[0024]
Further, the secondary combustion air from the secondary combustion air blower 10 and the exhaust gas discharged from the outlet of the boiler 7 are supplied into the gas mixing chamber 3, and the combustion exhaust gas that cannot be completely burned in the combustion chamber 2 is supplied. Completely burn the unburned gas inside. The combustion exhaust gas after the secondary combustion in the gas mixing chamber 3 is discharged outside after the thermal energy is recovered by the downstream boiler 7.
[0025]
Here, it is preferable to provide an intermediate ceiling 17 in the combustion chamber 2 as shown in FIG. By providing the intermediate ceiling 17 in the combustion chamber, the gas in the combustion chamber is divided into two parts, a combustible gas generated in a dust drying process on the upstream side of the grate 4 and a combustion exhaust gas generated in a post-combustion process on the downstream side. can do. By recombining the gas discharged after being divided into two in the gas mixing chamber 3, the stirring and mixing of the gas in the gas mixing chamber 3 is further promoted, the combustion in the gas mixing chamber 3 is further stabilized, and the combustion is performed. It is possible to further suppress the generation of dioxins in the process and prevent the generation of unburned waste. Needless to say, the present invention is also applied to a refuse incinerator having no intermediate ceiling 17.
[0026]
In the refuse incinerator having the above configuration, the first embodiment of the refuse incinerator according to the present invention includes a unit for measuring a gas temperature in the combustion chamber 2, a unit for measuring a gas temperature in the gas mixing chamber 3, Measured by means for measuring the oxygen concentration in the exhaust gas, means for measuring the gas temperature in the combustion chamber 2 measured by the means for measuring the gas temperature in the combustion chamber 2 and means for measuring the gas temperature in the gas mixing chamber 3. Supply of air and exhaust gas supplied into the gas mixing chamber as secondary combustion air based on the difference between the gas temperature in the gas mixing chamber and the oxygen concentration measured by the means for measuring the oxygen concentration in the exhaust gas. And a combustion control device 11 for controlling the amount.
[0027]
Here, as a means for measuring the gas temperature in the combustion chamber 2, for example, a combustion chamber gas thermometer 12 installed in the combustion chamber 2 can be used. As a means for measuring the gas temperature in the gas mixing chamber 3, for example, a gas thermometer 13 installed in the gas mixing chamber 3 can be used. As a means for measuring the oxygen concentration in the exhaust gas, for example, an oxygen concentration meter 14 installed at the outlet of the boiler 7 can be used.
[0028]
The combustion control device 11 measures the gas temperature in the combustion chamber measured by the gas thermometer 12 in the combustion chamber, the gas temperature in the gas mixing chamber measured by the gas thermometer 13 in the gas mixing chamber, and the gas concentration measured by the oxygen concentration meter 14. Means for taking in the oxygen concentration in the exhaust gas, means for comparing the gas temperature in the combustion chamber with the gas temperature in the gas mixing chamber, a comparison result between the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber, and based on the oxygen concentration in the exhaust gas. Means for controlling the supply amount of air and exhaust gas supplied into the gas mixing chamber as secondary combustion air. Note that a computer can be used as the combustion control device 11, for example.
[0029]
As shown in FIG. 2, the control of the supply amounts of the air and the exhaust gas supplied to the gas mixing chamber as the secondary combustion air is such that when the gas temperature in the gas mixing chamber is high, the oxygen concentration in the exhaust gas is low, Due to the shortage, the CO concentration increases. Therefore, when the gas temperature in the gas mixing chamber is higher than the gas temperature in the combustion chamber or the oxygen concentration is low, the proportion of air in the secondary combustion air is increased to burn unburned components such as CO. Suppress the occurrence.
[0030]
As a specific adjustment method, when the gas temperature in the gas mixing chamber 3 is higher than the gas temperature in the combustion chamber 2, the proportion of air in the secondary combustion air is increased, and the secondary air in the gas mixing chamber 3 is increased. The oxygen concentration in the combustion air is increased to suppress the generation of CO. Alternatively, when the oxygen concentration in the gas mixing chamber 3 is low, the CO concentration increases, so that the oxygen concentration in the secondary combustion air in the gas mixing chamber 3 is increased. The control of the air ratio in the secondary combustion air can be performed, for example, by constructing a fuzzy rule as shown in Table 1 below on a computer and incorporating the fuzzy rule into the combustion control device 11. The fuzzy rule uses the min-max method, the singleton method, or the like, for example, to determine the air ratio in the secondary combustion air in the consequent part.
[0031]
[Table 1]
Figure 2004293840
[0032]
Further, the second embodiment of the refuse incinerator according to the present invention has a means for measuring the gas temperature in the combustion chamber 2, a means for measuring the gas temperature in the gas mixing chamber 3, and an oxygen concentration in the exhaust gas. Means for measuring, means for measuring the CO concentration in the exhaust gas, and means for measuring the gas temperature in the combustion chamber 2 and the gas temperature in the gas mixing chamber 3 measured by the means for measuring the gas temperature in the combustion chamber 2 The gas temperature in the gas mixing chamber measured by the means for measuring, the oxygen concentration measured by the means for measuring the oxygen concentration in the exhaust gas, and the CO concentration measured by the means for measuring the CO concentration in the exhaust gas. And a combustion control device 11 for controlling the supply amount of air and exhaust gas supplied into the gas mixing chamber as secondary combustion air based on the above.
[0033]
Here, as a means for measuring the gas temperature in the combustion chamber 2, for example, a combustion chamber gas thermometer 12 installed in the combustion chamber 2 can be used. As a means for measuring the gas temperature in the gas mixing chamber 3, for example, a gas thermometer 13 installed in the gas mixing chamber 3 can be used. As a means for measuring the oxygen concentration in the exhaust gas, for example, an oxygen concentration meter 14 installed at the outlet of the boiler 7 can be used. As a means for measuring the CO concentration in the exhaust gas, for example, a CO concentration meter 15 installed at the outlet of the boiler 7 can be used.
[0034]
The combustion control device 11 measures the gas temperature in the combustion chamber measured by the gas thermometer 12 in the combustion chamber, the gas temperature in the gas mixing chamber measured by the gas thermometer 13 in the gas mixing chamber, and the gas concentration measured by the oxygen concentration meter 14. Means for taking in the oxygen concentration in the exhaust gas and the CO concentration in the exhaust gas measured by the CO concentration meter 15; means for comparing the gas temperature in the combustion chamber with the gas temperature in the gas mixing chamber; Means for controlling the supply amount of air and exhaust gas supplied to the gas mixing chamber as secondary combustion air based on the comparison result with the indoor gas temperature, the oxygen concentration in the exhaust gas, and the CO concentration in the exhaust gas. I have. Note that a computer can be used as the combustion control device 11, for example.
[0035]
As shown in FIG. 2, the control of the supply amounts of the air and the exhaust gas supplied to the gas mixing chamber as the secondary combustion air is such that when the gas temperature in the gas mixing chamber is high, the oxygen concentration in the exhaust gas is low, Due to the shortage, the CO concentration increases. For this reason, when the gas temperature in the gas mixing chamber is higher than the gas temperature in the combustion chamber, the oxygen concentration is low, or the CO concentration is high, the proportion of air in the secondary combustion air is increased, and Combustion of the fuel component suppresses its generation.
[0036]
As a specific adjustment method, in addition to the fuzzy rule shown in the first embodiment, the CO concentration in the exhaust gas is directly measured, and when the CO concentration in the exhaust gas is high, the CO concentration in the secondary combustion air is Adjust so as to reduce the amount of exhaust gas, increase air, increase the oxygen concentration, and reduce the CO concentration. Similarly, the control of the air ratio in the secondary combustion air can be performed by constructing a fuzzy rule as shown in Table 2 below on a computer and incorporating it in the combustion control device 11. The fuzzy rule uses the min-max method, the singleton method, or the like, for example, to determine the air ratio in the secondary combustion air in the consequent part.
[0037]
[Table 2]
Figure 2004293840
[0038]
Further, the third embodiment of the refuse incinerator according to the present invention has a means for measuring the gas temperature in the combustion chamber 2, a means for measuring the gas temperature in the gas mixing chamber 3, and a method for measuring the oxygen concentration in the exhaust gas. Means for measuring, means for measuring the CO concentration in the exhaust gas, means for measuring the NOx concentration in the exhaust gas, and the gas temperature in the combustion chamber 2 measured by the means for measuring the gas temperature in the combustion chamber 2. The difference from the gas temperature in the gas mixing chamber measured by the means for measuring the gas temperature in the gas mixing chamber 3, the oxygen concentration measured by the means for measuring the oxygen concentration in the exhaust gas, and the CO concentration in the exhaust gas Based on the CO concentration measured by the measuring means and the NOx concentration measured by the NOx concentration in the exhaust gas, supply of air and exhaust gas supplied to the gas mixing chamber as secondary combustion air is performed. It is obtained by a combustion control device 11 for controlling the amount.
[0039]
Here, as a means for measuring the gas temperature in the combustion chamber 2, for example, a combustion chamber gas thermometer 12 installed in the combustion chamber 2 can be used. As a means for measuring the gas temperature in the gas mixing chamber 3, for example, a gas thermometer 13 installed in the gas mixing chamber 3 can be used. As a means for measuring the oxygen concentration in the exhaust gas, for example, an oxygen concentration meter 14 installed at the outlet of the boiler 7 can be used. As a means for measuring the CO concentration in the exhaust gas, for example, a CO concentration meter 15 installed at the outlet of the boiler 7 can be used. As a means for measuring the NOx concentration in the exhaust gas, for example, a NOx concentration meter 16 installed at the outlet of the boiler 7 can be used.
[0040]
The combustion control device 11 measures the gas temperature in the combustion chamber measured by the gas thermometer 12 in the combustion chamber, the gas temperature in the gas mixing chamber measured by the gas thermometer 13 in the gas mixing chamber, and the gas concentration measured by the oxygen concentration meter 14. Means for taking in the oxygen concentration in the exhaust gas, the CO concentration in the exhaust gas measured by the CO concentration meter 15 and the NOx concentration in the exhaust gas measured by the NOx concentration meter 16, the gas temperature in the combustion chamber, the gas temperature in the gas mixing chamber, Means for comparing the temperature of the gas in the combustion chamber with the temperature of the gas in the gas mixing chamber, and based on the oxygen concentration in the exhaust gas, the CO concentration in the exhaust gas, and the NOx concentration in the exhaust gas, mix the gas as the secondary combustion air. Means for controlling the supply amounts of air and exhaust gas supplied into the room. Note that a computer can be used as the combustion control device 11, for example.
[0041]
As shown in FIG. 2, the control of the supply amounts of the air and the exhaust gas supplied to the gas mixing chamber as the secondary combustion air is such that when the gas temperature in the gas mixing chamber is high, the oxygen concentration in the exhaust gas is low, Due to the shortage, the CO concentration increases. Therefore, when the gas temperature in the gas mixing chamber is higher than the gas temperature in the combustion chamber, the oxygen concentration is low, or the CO concentration is high, the proportion of air in the secondary combustion air is increased to reduce Combustion of the fuel component suppresses its generation. In addition, as shown in FIG. 3, if the proportion of air in the secondary combustion air is reduced, the NOx concentration in the exhaust gas can be reduced. By comprehensively adjusting based on the components, the concentrations of CO and NOx in the exhaust gas can be reduced at the same time.
[0042]
As a specific adjustment method, in addition to the fuzzy rule shown in the above-described second embodiment, the NOx concentration in the exhaust gas is measured, and if the NOx concentration is high and the CO concentration is low, the NOx concentration in the secondary combustion air is measured. A fuzzy rule is added to reduce the oxygen concentration by reducing the proportion of the air amount and reduce the NOx concentration. Similarly, the control of the air ratio in the secondary combustion air can be performed by constructing a fuzzy rule as shown in Table 3 below on a computer and incorporating it in the combustion control device 11. The fuzzy rule uses the min-max method, the singleton method, or the like, for example, to determine the air ratio in the secondary combustion air in the consequent part.
[0043]
[Table 3]
Figure 2004293840
[0044]
【The invention's effect】
As described above, according to the present invention, even when combustion is performed at a low air ratio, stable combustion of refuse on the grate can be realized, and the CO concentration and the NOx concentration in the exhaust gas can be reduced. Provided are a combustion control method for a grid-type waste incinerator and a waste incinerator.
[Brief description of the drawings]
FIG. 1 is a diagram showing the results of examining the characteristics of the CO concentration in exhaust gas at the boiler outlet with respect to the difference between the gas temperature in a combustion chamber and the gas temperature in a gas mixing chamber in an actual refuse incinerator.
FIG. 2 is a diagram showing the results of examining characteristics of O 2 concentration in exhaust gas, CO concentration in exhaust gas, and gas temperature in a gas mixing chamber.
FIG. 3 is a diagram showing the results of examining the characteristics of the oxygen concentration in secondary combustion air obtained by mixing exhaust gas and air discharged from a furnace and the NOx concentration in exhaust gas.
FIG. 4 is a schematic configuration diagram showing an embodiment of a refuse incinerator according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hopper 2 Combustion chamber 3 Gas mixing chamber 4 Grate 5 Dust supply device 6 Ash fall port 7 Boiler 8 Primary combustion air blowers 9a, 9b, 9c, 9d Primary combustion air damper 10 below grate 10 Secondary combustion air blower 11 Combustion control device 12 Gas thermometer in combustion chamber 13 Gas thermometer in gas mixing chamber 14 Oxygen concentration meter 15 CO concentration meter 16 NOx concentration meter 17 Intermediate ceiling

Claims (6)

火格子式ごみ焼却炉の燃焼制御方法であって、
燃焼室内のガス温度とガス混合室内のガス温度との差、及び、排ガス中の酸素濃度に基づいて、
二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を調整することを特徴とする火格子式ごみ焼却炉の燃焼制御方法。A combustion control method for a grate-type incinerator,
Based on the difference between the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber, and the oxygen concentration in the exhaust gas,
A combustion control method for a grate-type incinerator, comprising adjusting the supply amounts of air and exhaust gas supplied into a gas mixing chamber as secondary combustion air. 火格子式ごみ焼却炉の燃焼制御方法であって、
燃焼室内のガス温度とガス混合室内のガス温度との差、排ガス中の酸素濃度、及び、排ガス中のＣＯ濃度に基づいて、
二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を調整することを特徴とする火格子式ごみ焼却炉の燃焼制御方法。A combustion control method for a grate-type incinerator,
Based on the difference between the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber, the oxygen concentration in the exhaust gas, and the CO concentration in the exhaust gas,
A combustion control method for a grate-type incinerator, comprising adjusting the supply amounts of air and exhaust gas supplied into a gas mixing chamber as secondary combustion air. 火格子式ごみ焼却炉の燃焼制御方法であって、
燃焼室内のガス温度とガス混合室内のガス温度との差、排ガス中の酸素濃度、排ガス中のＣＯ濃度、及び、排ガス中のＮＯｘ濃度に基づいて、
二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を調整することを特徴とする火格子式ごみ焼却炉の燃焼制御方法。A combustion control method for a grate-type incinerator,
Based on the difference between the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber, the oxygen concentration in the exhaust gas, the CO concentration in the exhaust gas, and the NOx concentration in the exhaust gas,
A combustion control method for a grate-type incinerator, comprising adjusting the supply amounts of air and exhaust gas supplied into a gas mixing chamber as secondary combustion air. 燃焼室内のガス温度を計測する手段と、
ガス混合室内のガス温度を計測する手段と、
排ガス中の酸素濃度を計測する手段と、
前記燃焼室内のガス温度を計測する手段により計測された燃焼室内ガス温度と前記ガス混合室内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、及び、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置とを備えたことを特徴とする火格子式ごみ焼却炉。Means for measuring the gas temperature in the combustion chamber;
Means for measuring the gas temperature in the gas mixing chamber;
Means for measuring the oxygen concentration in the exhaust gas;
The difference between the gas temperature in the combustion chamber measured by the means for measuring the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber measured by the means for measuring the gas temperature in the gas mixing chamber; and the oxygen in the exhaust gas. A fire control device for controlling the supply amount of air and exhaust gas supplied to the gas mixing chamber as secondary combustion air based on the oxygen concentration measured by the concentration measuring means. Grid type incinerator. 燃焼室内のガス温度を計測する手段と、
ガス混合室内のガス温度を計測する手段と、
排ガス中の酸素濃度を計測する手段と、
排ガス中のＣＯ濃度を計測する手段と、
前記燃焼室内のガス温度を計測する手段により計測された燃焼室内ガス温度と前記ガス混合室内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度、及び、前記排ガス中のＣＯ濃度を計測する手段により計測されたＣＯ濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置とを備えたことを特徴とする火格子式ごみ焼却炉。Means for measuring the gas temperature in the combustion chamber;
Means for measuring the gas temperature in the gas mixing chamber;
Means for measuring the oxygen concentration in the exhaust gas;
Means for measuring the CO concentration in the exhaust gas;
The difference between the gas temperature in the combustion chamber measured by the means for measuring the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber measured by the means for measuring the gas temperature in the gas mixing chamber, the oxygen concentration in the exhaust gas. Supply of air and exhaust gas supplied into the gas mixing chamber as secondary combustion air based on the oxygen concentration measured by the measuring means and the CO concentration measured by the CO concentration in the exhaust gas; A grate-type incinerator comprising a combustion control device for controlling the amount. 燃焼室内のガス温度を計測する手段と、
ガス混合室内のガス温度を計測する手段と、
排ガス中の酸素濃度を計測する手段と、
排ガス中のＣＯ濃度を計測する手段と、
排ガス中のＮＯｘ濃度を計測する手段と、
前記燃焼室内のガス温度を計測する手段により計測された燃焼室内ガス温度と前記ガス混合室内のガス温度を計測する手段により計測されたガス混合室内ガス温度との差、前記排ガス中の酸素濃度を計測する手段により計測された酸素濃度、前記排ガス中のＣＯ濃度を計測する手段により計測されたＣＯ濃度、及び、前記排ガス中のＮＯｘ濃度を計測する手段により計測されたＮＯｘ濃度に基づいて、二次燃焼用空気としてガス混合室内に供給される空気と排ガスの供給量を制御する燃焼制御装置とを備えたことを特徴とする火格子式ごみ焼却炉。Means for measuring the gas temperature in the combustion chamber;
Means for measuring the gas temperature in the gas mixing chamber;
Means for measuring the oxygen concentration in the exhaust gas;
Means for measuring the CO concentration in the exhaust gas;
Means for measuring the NOx concentration in the exhaust gas;
The difference between the gas temperature in the combustion chamber measured by the means for measuring the gas temperature in the combustion chamber and the gas temperature in the gas mixing chamber measured by the means for measuring the gas temperature in the gas mixing chamber, the oxygen concentration in the exhaust gas. Based on the oxygen concentration measured by the measuring means, the CO concentration measured by the means for measuring the CO concentration in the exhaust gas, and the NOx concentration measured by the NOx concentration in the exhaust gas. A grate-type incinerator, comprising: a combustion control device that controls supply amounts of air and exhaust gas supplied to a gas mixing chamber as next combustion air.
JP2003084307A 2003-03-26 2003-03-26 Combustion control method of fire grate garbage incinerator Pending JP2004293840A (en)

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006292264A (en) * 2005-04-08 2006-10-26 Mitsubishi Heavy Ind Ltd Method and system for waste combustion treatment
JP2009243765A (en) * 2008-03-31 2009-10-22 Mitsui Eng & Shipbuild Co Ltd Combustion control method, and waste treatment device
CN102721068A (en) * 2012-07-11 2012-10-10 光大环保科技发展（北京）有限公司 Method for controlling air supply system of water-cooling reciprocating multistage hydraulic mechanical grate furnace
CN104334971A (en) * 2012-03-29 2015-02-04 日立造船株式会社 Combustion driving method in incinerator
CN104990083A (en) * 2015-08-07 2015-10-21 浙江伟明环保股份有限公司 Life garbage and garbage leachate biogas and sludge mixing combustion incinerator
CN104334971B (en) * 2012-03-29 2016-11-30 日立造船株式会社 The burning method of operation of incinerator
CN104748129B (en) * 2013-12-30 2017-10-24 川崎重工业株式会社 Grate type incinerator
CN109099434A (en) * 2018-07-23 2018-12-28 深圳市能源环保有限公司 Low-nitrogen combustion control method for garbage incinerator
CN115681993A (en) * 2022-11-12 2023-02-03 江苏大鸿环保设备有限公司 High-temperature combustion-supporting air distribution system of hazardous waste garbage incinerator and use method thereof

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006292264A (en) * 2005-04-08 2006-10-26 Mitsubishi Heavy Ind Ltd Method and system for waste combustion treatment
JP2009243765A (en) * 2008-03-31 2009-10-22 Mitsui Eng & Shipbuild Co Ltd Combustion control method, and waste treatment device
CN104334971A (en) * 2012-03-29 2015-02-04 日立造船株式会社 Combustion driving method in incinerator
CN104334971B (en) * 2012-03-29 2016-11-30 日立造船株式会社 The burning method of operation of incinerator
CN102721068A (en) * 2012-07-11 2012-10-10 光大环保科技发展（北京）有限公司 Method for controlling air supply system of water-cooling reciprocating multistage hydraulic mechanical grate furnace
CN102721068B (en) * 2012-07-11 2016-06-08 光大环保科技发展（北京）有限公司 A kind of control method of water-cooled reciprocating-type multi-stage hydraulic mechanical grate furnace air feed system
CN104748129B (en) * 2013-12-30 2017-10-24 川崎重工业株式会社 Grate type incinerator
CN104990083A (en) * 2015-08-07 2015-10-21 浙江伟明环保股份有限公司 Life garbage and garbage leachate biogas and sludge mixing combustion incinerator
CN109099434A (en) * 2018-07-23 2018-12-28 深圳市能源环保有限公司 Low-nitrogen combustion control method for garbage incinerator
CN115681993A (en) * 2022-11-12 2023-02-03 江苏大鸿环保设备有限公司 High-temperature combustion-supporting air distribution system of hazardous waste garbage incinerator and use method thereof
CN115681993B (en) * 2022-11-12 2023-08-04 江苏大鸿环保设备有限公司 High-temperature combustion-supporting air distribution system of hazardous waste incinerator and application method thereof

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