JP4479655B2 - Grate-type waste incinerator and its combustion control method - Google Patents

Description

【表２】

焼却炉内で廃棄物と熱分解によって発生する可燃性ガスを適正な酸素濃度や温度等の範囲内で燃焼させた場合に、ＣＯ、ＮＯｘ、ＤＸＮ（ダイオキシン類）等の有害物質の発生が最も抑制される。
表１において、二次燃焼領域１７出口近傍でのガス温度が高い場合（（１）の場合）は、燃焼室での燃焼が抑制され、その結果二次燃焼領域での燃焼が急激に行われるためガス温度が上昇していると考えられる。この場合、焼却炉から排出されるＣＯ濃度及びＤＸＮ濃度は減少するか変化が無いがＮＯｘ濃度は増加する。そのため、Ｑ３のみを調整する場合は、Ｑ３を増加させて燃焼室内への酸素の供給量を増加し、燃焼室内での燃焼を活発に行うようにして二次燃焼領域での燃焼を適正化させる。Ｑ４のみを調整する場合は、Ｑ４を減少させ、二次燃焼領域への酸素の供給量を減少させて二次燃焼領域での燃焼を適正に行うようにする。Ｑ３＋Ｑ４の合計値を調整する場合は、Ｑ３を増加させ、Ｑ４を減少させて、Ｑ３＋Ｑ４の合計値は増加させるか変化無しで燃焼室及び二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス中Ｏ₂濃度が高い場合（（２）の場合）は、焼却炉から排出されるＣＯ濃度及びＤＸＮ濃度は減少するか変化は無いが、ＮＯｘ濃度は増加する。そのため、Ｑ３のみを調整する場合は、Ｑ３を増加させて燃焼室内への酸素の供給量を増加し、燃焼室での燃焼を活発に行うようにして酸素の消費量を増加させる。Ｑ４のみを調整する場合は、Ｑ４を減少させ、二次燃焼領域への酸素の供給量を減少させて二次燃焼領域での燃焼を適正に行うようにする。Ｑ３＋Ｑ４の合計値を調整する場合は、Ｑ３を増加させ、Ｑ４を減少させて、Ｑ３＋Ｑ４の合計値は増加させるか変化無しで燃焼室及び二次燃焼領域での燃焼を適正に行うようにする。
反対に、二次燃焼領域１７出口近傍でのガス中Ｏ₂濃度が低い場合（（３）の場合）は、焼却炉から排出されるＮＯｘ濃度は減少するが、ＣＯ濃度及びＤＸＮ濃度は増加するか変化の無い状態となる。そのため、Ｑ３のみを調整する場合は、Ｑ３を減少させて燃焼室内での循環排ガスによる希釈割合を減らし、二次燃焼領域における酸素濃度を高める。Ｑ４のみを調整する場合は、Ｑ４を増加させ、二次燃焼領域への酸素の供給量を増やす。Ｑ３＋Ｑ４の合計値を調整する場合は、Ｑ３を減少させ、Ｑ４を増加させて、Ｑ３＋Ｑ４の合計値は増加させて燃焼室及び二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス中ＣＯ濃度が高い場合（（４）の場合）は、二次燃焼領域での燃焼が不十分であり、未燃焼の可燃性ガスが残存していると考えられる。そのため、Ｑ３のみを調整する場合は、Ｑ３を減少させて二次燃焼領域での温度を高めて燃焼を安定化させＣＯの排出を抑制する。Ｑ４のみを調整する場合は、Ｑ４を増加させて二次燃焼領域への酸素の供給量を増やし二次燃焼領域での燃焼を適正に行うようにする。Ｑ３＋Ｑ４の合計値は増加させて燃焼室及び二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス温度が低く、ガス中Ｏ₂濃度が高い場合（（５）の場合）は、攪拌用ガスの流量が過剰であるため、二次燃焼領域内の温度が低下し、燃焼が不安定になっていると考えられる。この場合、焼却炉から排出されるＣＯ濃度及びＤＸＮ濃度が増加する。そのため、Ｑ３は増加か変化無しで、Ｑ４を減少させ、二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス温度が低く、ガス中Ｏ₂濃度が低い場合（（６）の場合）は、二次燃焼領域内での燃焼が抑制され、ガス温度が低下していると考えられる。この場合、焼却炉から排出されるＣＯ濃度及びＤＸＮ濃度が増加する。そのため、Ｑ３を減少させ燃焼室での温度を高めて可燃性ガスの二次燃焼領域への流入量を増やし、Ｑ４を増加させて二次燃焼領域への酸素の供給量を増やし二次燃焼領域での燃焼を適正に行うようにする。Ｑ３＋Ｑ４の合計値は増加させるか変化無しで燃焼室及び二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス中ＣＯ濃度が高く、ガス温度が高い場合（（７）の場合）は、燃焼室での燃焼が不完全で、二次燃焼領域での燃焼が急激に行われるためガス温度が上昇しており、また、未燃焼の可燃性ガスが残存していると考えられる。この場合、焼却炉から排出されるＣＯ濃度及びＤＸＮ濃度が増加する。そのため、Ｑ３を増加させて燃焼室内の温度を低下させると共に、Ｑ４を増加させて二次燃焼領域の温度を低下させつつ二次燃焼領域への酸素の供給量を増やし二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス中ＣＯ濃度が高く、ガス温度が低い場合（（８）の場合）は、廃棄物の供給量が減って燃焼室内に吹き込む循環排ガスの流量が過剰になったため、炉内温度が低下し、燃焼が不安定になっていると考えられる。この場合、焼却炉から排出されるＣＯ濃度及びＤＸＮ濃度が増加する。そのため、Ｑ３を減少させて炉内温度を上昇させ燃焼を安定化させると共に、Ｑ４を増加させて二次燃焼領域への酸素の供給量を増やし二次燃焼領域での燃焼を適正に行うようにする。Ｑ３＋Ｑ４の合計値は増加させるか変化無しで燃焼室及び二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス中ＮＯｘ濃度が高く、ガス温度が高い場合（（９）の場合）は、燃焼室での燃焼が抑制され、その結果二次燃焼領域での燃焼が急激に行われるためガス温度が上昇し、ガス中ＮＯｘ濃度が増加していると考えられる。そのため、Ｑ３を増加させて燃焼室内の温度を低下させ、燃焼室での燃焼を抑制すると共に、Ｑ４を減少させ、二次燃焼領域への酸素の供給量を減少させて二次燃焼領域での燃焼を適正に行うようにする。Ｑ３＋Ｑ４の合計値は増加させるか変化無しで燃焼室及び二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス中ＮＯｘ濃度が低いが、ＣＯ濃度が高い場合（（１０）の場合）は、二次燃焼領域内での燃焼が不十分であり、未燃焼の可燃性ガスが残存していると考えられる。そのため、Ｑ３を減少させ燃焼室内での温度を高めて可燃性ガスの二次燃焼領域への流入量を増やし、Ｑ４を増加させて二次燃焼領域への酸素の供給量を増やし二次燃焼領域での燃焼を適正に行うようにする。Ｑ３＋Ｑ４の合計値は増加させて燃焼室及び二次燃焼領域での燃焼を適正に行うようにする。
二次燃焼領域１７出口近傍でのガス中ＮＯｘ濃度が低く、ＣＯ濃度も低い場合（（１１）の場合）は、炉内の燃焼が適正に行われている状態と考えられる。この場合は特に調節の必要は無くＱ３，Ｑ４，Ｑ３＋Ｑ４の合計値はそのままで維持する。
上記のように制御することにより、複雑な制御を行うことなく効果的に廃棄物焼却炉から排出されるＣＯ、ＮＯｘ、ＤＸＮ等の有害物質の量を低減することが可能となる。
また、表３には、実際の廃棄物焼却炉において、実施例としてＱ１：Ｑ２：Ｑ３：Ｑ４＝0.98：0.10：0.12：0.10、λ＝１．３０として廃棄物の燃焼を行った場合に、焼却炉から排出される排ガス中のＣＯ濃度、ＮＯｘ濃度、ＤＸＮ濃度を測定した結果を示す。なお、表３には、比較例１及び比較例２として、従来技術に係る廃棄物焼却炉において、火格子下から吹き込む燃焼用一次空気により供給される単位時間当りの酸素量ｒ１、主燃焼領域に吹き込む空気により供給される単位時間当りの酸素量ｒ２、後燃焼領域に吹き込む空気により供給される単位時間当りの酸素量ｒ３及びλ’＝ｒ１＋ｒ２＋ｒ３を表２に示すように設定した場合の焼却炉の炉出口から排出される排ガス中のＣＯ濃度、ＮＯｘ濃度、ＤＸＮ濃度を測定した結果を示す。
【表３】

表３に示すように、実施例では、低空気比燃焼（λ＝１．３０）が達成でき、ＣＯ、ＮＯｘ、ＤＸＮの発生が抑制されている。それに対し、比較例１では、低空気比燃焼が達成できず（λ’＝１．７）、またＮＯｘの発生量が多い。比較例２では、低空気比燃焼（λ’＝１．３）を行うと、ＮＯｘの発生量は低くなるが、ＣＯの発生が多い。これは、炉内の燃焼状態が不安定になり、可燃性ガスが未燃のままＣＯとして排出されており、さらに煤などの未燃分が発生し、これらによりダイオキシン類の発生量も高くなっていると考えられる。
また、高温ガス、循環排ガス及び攪拌用ガスの吹き込み流量の調整を焼却炉から排出される排ガス流量に対する比率を用いて行ってもよい。これにより、簡便に吹き込み流量の設定や調整を行うことができる。
なお、上述した廃棄物焼却炉が灰溶融炉を一体化した灰溶融炉一体型廃棄物焼却炉である場合、上述の循環排ガス及び／又は攪拌用ガスの全部又は一部を灰溶融炉の排ガスを使用するようにしてもよい。また、前記灰溶融炉が、キルンフードを備えたキルン式灰溶融炉である場合には、上述の高温ガス及び／又は攪拌用ガスの全部又は一部に前記キルンフードを介して誘引された該キルンフード内で加熱された空気を使用することもできる。灰溶融炉の排ガス又はキルンフード内で加熱された空気を用いることにより廃熱を有効に活用することができ、省エネルギー化を図ることが可能となる。
以上説明したように本発明によれば、廃棄物焼却炉において低空気比燃焼を行った場合においても燃焼の安定性が維持され、且つ、局所高温領域の発生が抑制され、ＣＯやＮＯｘ等の有害ガスの発生量が低減できる廃棄物焼却炉の燃焼制御方法及び廃棄物焼却炉が提供される。さらに、低空気比燃焼を行えるので焼却炉から排出される排ガス総量を大幅に低減でき、また、廃熱の回収効率を向上できる廃棄物焼却炉の燃焼制御方法及び廃棄物焼却炉が提供される。
【図面の簡単な説明】
【０００６】
【図１】本発明に係る廃棄物焼却炉の一実施形態を示す概略側断面図である。
【図２】本発明に係る排ガスに混合される空気量調節手段の概略構成の一例を示す図である。
【図３】従来技術に係る廃棄物焼却炉の一例を示す概略側断面図である。【Technical field】
[0001]
  The present invention relates to a combustion control method for a grate-type waste incinerator that incinerates general waste, industrial waste, waste such as sewage sludge, and a grate-type suitable for implementing such a combustion control method. Regarding waste incineration.
[Prior art]
[0002]
  Grate-type waste incinerators are widely used as incinerators for incinerating waste such as municipal waste. A schematic diagram of a representative one is shown in FIG. The waste 32 thrown into the hopper 31 is sent to the drying grate 33 through a chute, dried by air from below and radiant heat in the furnace, and heated to ignite. The waste 32 ignited and started to burn is sent to the combustion grate 34, pyrolyzed and gasified by the combustion air sent from below, and a part is burned. Further, the unburned matter in the waste is completely burned by the post-burning grate 35. The ash remaining after combustion is taken out from the main ash chute 36.
  Combustion is performed in the combustion chamber 37, secondary combustion is performed in the secondary combustion chamber 41, and the combustible gas is completely combusted. The exhaust gas from the secondary combustion chamber 41 is sent to the waste heat boiler 43, and after heat exchange, it is discharged to the outside through a temperature reducing tower, a bag filter, and the like.
  In such a grate-type waste incinerator, when waste is incinerated, it is difficult to keep the combustion state in the furnace constant because the waste consists of many substances with different properties. It is inevitable that the temperature in the chamber 37 and the concentration distribution of the combustion gas will be non-uniform in time and space.
  As a method for solving such a problem, Japanese Patent Application Laid-Open No. 11-2111044 (Patent Document 1) discloses a method in which high-temperature gas generated by a regenerative burner is blown into a main combustion chamber or a secondary combustion chamber of an incinerator. Is disclosed. This technique is intended to reduce unburned gas and harmful substances containing a large amount of CO and aromatic hydrocarbons in exhaust gas generated in an incinerator.
  Japanese Patent Laid-Open No. 11-270829 (Patent Document 2) describes in the combustion exhaust gas so that the CO concentration in the combustion exhaust gas generated in the waste incinerator becomes a preset value for dioxin reduction. CO value of O₂A method for controlling the grate speed, the amount of combustion air and the amount of air for cooling the furnace temperature of the incinerator based on the value and the in-furnace temperature of the incinerator is disclosed.
[Patent Document 1]
JP 11-2111044 A
[Patent Document 2]
JP-A-11-270829
DISCLOSURE OF THE INVENTION
[Problems to be Solved by the Invention]
[0003]
  Conventionally, in a waste incinerator, the ratio (air ratio) obtained by dividing the amount of air actually supplied into the furnace by the theoretical amount of air necessary for the combustion of waste is about 1.7 to 2.0. This is larger than 1.05 to 1.2 which is an air ratio necessary for combustion of a general fuel. The reason for this is that waste contains more non-combustible and non-homogeneous than other liquid fuels and gaseous fuels, so the efficiency of air utilization is low and a large amount of air is required for combustion. is there. However, as the air ratio increases, the amount of exhaust gas increases, and accordingly, a larger exhaust gas treatment facility is required.
  If the air ratio is reduced, the amount of exhaust gas is reduced and the exhaust gas treatment facility becomes compact. As a result, the entire waste incineration facility can be reduced in size and the equipment cost can be reduced. In addition, since the amount of chemicals for exhaust gas treatment can be reduced, the operating cost can be reduced. Furthermore, since the amount of heat that cannot be recovered and discarded to the atmosphere can be reduced, the heat recovery rate of the waste heat boiler can be improved, and the efficiency of waste power generation can be increased accordingly.
  As described above, although the advantage over the low air ratio combustion is great, there is a problem that the combustion becomes unstable in the low air ratio combustion. That is, when burned at a low air ratio, the combustion becomes unstable, the generation of CO increases, the flame temperature rises locally, NOx increases rapidly, a large amount of soot is generated, and clinker is generated However, there is a problem that the life of the refractory in the furnace is shortened due to a local high temperature. In the combustion techniques described in Patent Document 1 and Patent Document 2, it has been insufficient to solve such problems.
  Moreover, as air for cooling the furnace temperature, using only air or mixing the exhaust gas from the incinerator with the air introduces new air into the furnace, so the total amount of exhaust gas cannot be reduced. There is also.
  In addition, there are known methods for improving the stability of combustion and reducing unburned components in exhaust gas by applying preheated air or oxygen-enriched air. There is a problem in practical use.
  On the other hand, as typified by swirl combustion, a method of reducing the concentration of unburned matter in exhaust gas by devising the form of air blown into the furnace is generally applied, but improves the combustibility. This requires more air, requires a larger blower and exhaust gas treatment equipment, increases running costs and equipment costs, and increases the amount of heat carried by the exhaust gas (sensible heat), resulting in lower power generation efficiency. There is a problem.
  In addition, if exhaust gas is excessively blown into a region where the fuel concentration is low, such as a secondary combustion region, combustion may become unstable with a decrease in reactivity, causing misfire or an increase in unburned content in the exhaust gas. In particular, when the change in the waste quality is large, such a phenomenon appears to be amplified, which causes a problem in terms of pollution countermeasures.
  As described above, it is difficult to achieve both a reduction in pollution (a reduction in NOx, CO, etc.) and a reduction in cost with conventional combustion improvement means alone.
  The present invention has been made to solve the above problems, and even when low air ratio combustion is performed in a waste incinerator, the generation amount of harmful gases such as CO and NOx can be reduced, and further emitted from a chimney. It is an object of the present invention to provide a waste incinerator combustion control method and a waste incinerator capable of greatly reducing the total amount of exhaust gas.
[Means for Solving the Problems]
[0004]
  The features of the present invention for solving such problems are as follows.
[1].
  A combustion control method for a grate-type waste incinerator,
  The primary air A for combustion is blown into the combustion chamber from below the grate,
  Hot gas B is blown into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber,
  The circulating exhaust gas C containing at least a part of the exhaust gas discharged from the incinerator is blown above the hot gas B blowing position or downstream in the gas flow direction,
  Agitating gas D consisting of either air, circulating exhaust gas, or a mixed gas of air and circulating exhaust gas is blown into the secondary combustion region,
  The hot gas B has a temperature in the range of 300 to 600 ° C. and an oxygen concentration in the range of 5 to 18%.
[2].
  In the above [1],
  The circulating exhaust gas C consists only of exhaust gas discharged from the incinerator.
[3].
  In the above [1] or [2],
  For theoretical oxygen per unit time required for combustion of waste
  A ratio Q1 of oxygen amount per unit time supplied by the combustion primary air A;
  A ratio Q2 of the amount of oxygen per unit time supplied by the hot gas B;
  A ratio Q3 of oxygen amount per unit time supplied by the circulating exhaust gas C;
  The ratio Q4 of the amount of oxygen per unit time supplied by the stirring gas D satisfies the following expressions (1) and (2):
Q1: Q2: Q3: Q4 = 0.75-1.20: 0.05-0.20: 0.02-0.20: 0.02-0.25 (1)
1.2 ≦ Q1 + Q2 + Q3 + Q4 ≦ 1.5 (2).
[4].
  In the above [1] or [2],
  For theoretical oxygen per unit time required for combustion of waste
  A ratio Q1 of oxygen amount per unit time supplied by the combustion primary air A;
  A ratio Q2 of the amount of oxygen per unit time supplied by the hot gas B;
  A ratio Q3 of oxygen amount per unit time supplied by the circulating exhaust gas C;
  The ratio Q4 of the amount of oxygen per unit time supplied by the stirring gas D satisfies the following expressions (3) and (4):
Q1: Q2: Q3: Q4 = 0.75-1.1: 0.07-0.15: 0.02-0.15: 0.02-0.25 (3)
1.25 ≦ Q1 + Q2 + Q3 + Q4 ≦ 1.35 (4).
[5].
  In any one of the above [1] to [4]
  The hot gas B is blown in an arbitrary region between a height position not exceeding 50% of the combustion chamber height and from the combustion start region to the main combustion region in the combustion chamber in a blowing direction in a range from horizontal to downward 20 °. It is characterized by that.
[6].
  In any one of the above [1] to [4]
  Arbitrary region where the hot gas B extends from the height position within the range of 0.2 to 1.5 m vertically upward from the waste layer surface on the grate to the main combustion region from the combustion start region in the combustion chamber The air is blown in the blowing direction in a range from horizontal to downward 20 °.
[7].
  In any one of the above [1] to [4]
  The hot gas B is vertically downward 20 from a height position within a range of 0.2 to 2.5 m vertically upward from the grate surface to any region between the combustion start region and the main combustion region in the combustion chamber. It is characterized by being blown in the blowing direction in the range up to °°.
[8].
  In any one of the above [1] to [7]
  The high temperature gas B is blown into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber at a blowing rate of 10 times or more the superficial velocity in the furnace.
[9].
  In any one of [1] to [8] above,
  When the gas temperature is raised, the flow rate of the circulating exhaust gas C is reduced when the gas temperature is raised, and when the gas temperature is lowered, the stirring gas is used for the stirring. The flow rate of the gas D is adjusted so as to increase.
[10].
  In any one of the above [1] to [9]
  The stirring gas D is blown so that a swirling flow is formed in the secondary combustion region.
[11].
  In any one of the above [1] to [10]
  The flow rate of the hot gas B is adjusted so that the temperature of the primary combustion exhaust gas that has passed through the combustion start region or the main combustion region becomes higher than the temperature of the primary combustion exhaust gas that has passed through the post-combustion region.
[12].
  In any one of the above [1] to [11],
  Increasing the flow rate of the hot gas B when raising the temperature of the primary combustion exhaust gas so that the temperature of the primary combustion exhaust gas passing through the main combustion region and the post-combustion region is in the range of 800 to 1050 ° C., respectively At least one of reducing the flow rate of the circulating exhaust gas C, and at the time of lowering the primary combustion exhaust gas temperature, at least of reducing the flow rate of the hot gas B and increasing the flow rate of the circulating exhaust gas C. It is characterized by adjusting to do one.
[13].
  In any one of the above [1] to [11],
  When increasing the temperature of the primary combustion exhaust gas so that the temperature of the primary combustion exhaust gas passing through the main combustion region and the post-combustion region is in the range of 800 to 1050 ° C., respectively, the oxygen concentration of the hot gas B is increased. And at least one of increasing the temperature, and at the time of decreasing the primary combustion exhaust gas temperature, at least one of decreasing the oxygen concentration of the hot gas B and decreasing the temperature is performed. It is characterized by adjusting.
[14].
  Combustion primary air blowing means for blowing combustion primary air A into the combustion chamber from below the grate,
  High-temperature gas blowing means for blowing high-temperature gas B having a temperature in the range of 300 to 600 ° C. and an oxygen concentration in the range of 5 to 18% into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber. When,
  Circulating exhaust gas blowing means for blowing circulating exhaust gas C containing at least a part of the exhaust gas discharged from the incinerator above the hot gas B blowing position or downstream in the gas flow direction;
  Grate-type disposal characterized by comprising stirring gas blowing means for blowing a stirring gas D consisting of either air, circulating exhaust gas, or a mixed gas of air and circulating exhaust gas into the secondary combustion region It is a waste incinerator.
[15].
  In the above [14],
  The hot gas B blowing nozzle is provided at a height position not exceeding 50% of the height of the combustion chamber in a blowing direction in a range from horizontal to downward 20 °.
[16].
  In the above [14],
  The hot gas B blowing nozzle is provided at a height position within a range of 0.2 to 1.5 m vertically upward from the waste layer surface on the grate in a blowing direction ranging from horizontal to 20 ° downward. It is characterized by being.
[17].
  In the above [14],
  The hot gas B blowing nozzle is provided at a height position in the range of 0.2 to 2.5 m vertically upward from the grate surface in a blowing direction in the range of 20 ° downward from the horizontal. To do.
[18].
  In any one of the above [14] to [17]
  A stirring nozzle D is provided so that a swirling flow is formed in the secondary combustion region.
[19].
  In any one of [14] to [18] above,
  It is provided with means capable of adjusting the flow rate of the high temperature gas B so that the temperature of the primary combustion exhaust gas passing through the combustion start region or the main combustion region becomes higher than the temperature of the primary combustion exhaust gas passing through the post combustion region. And
[20].
  In any one of the above [14] to [19]
  Provided with means capable of adjusting the flow rate of the hot gas B and / or the circulating exhaust gas C so that the temperature of the primary combustion exhaust gas passing through the main combustion region and the post-combustion region is in the range of 800 to 1050 ° C., respectively. Features.
[21].
  In any one of the above [14] to [19]
  Provided with means capable of adjusting the oxygen concentration and / or gas temperature of the hot gas B so that the temperature of the primary combustion exhaust gas passing through the main combustion region and the post-combustion region is in the range of 800 to 1050 ° C., respectively. Features.
[0005]
  Hereinafter, an embodiment of the present invention will be described.
  FIG. 1 is a schematic sectional side view showing an embodiment of a waste incinerator 30 according to the present invention.
  A waste incinerator 30 shown in FIG. 1 includes a combustion chamber 3, a hopper 1 disposed on the upstream side (left side in FIG. 1) of the combustion chamber 3 for introducing waste 2 into the combustion chamber 3, This is a grate-type dual-flow furnace having a boiler 12 connected to the upper side of the downstream side of the combustion chamber 3 opposite to the hopper 1.
  At the bottom of the combustion chamber 3 is provided a grate (stoker) that burns the waste 2 while moving it. This grate is provided so as to incline so as to be lowered as the distance from the hopper 1 increases. The grate is formed with two steps and is divided into three parts. These three grates are called a dry grate 5, a combustion grate 6, and a post-combustion grate 7 from the side closer to the hopper 1. In the dry grate 5, the waste 2 is mainly dried and ignited. In the combustion grate 6, the waste 2 is mainly thermally decomposed and partially oxidized, and combustible gas is combusted. The combustion of the waste 2 in the combustion grate 6 is substantially completed. On the post-combustion grate 7, the remaining unburned matter in the waste 2 is completely burned. The combustion ash after complete combustion is discharged from the main ash chute 15.
  Below the dry grate 5, the combustion grate 6, and the post-combustion grate 7, wind boxes 8, 9, and 10 are provided, respectively. The combustion primary air supplied by the blower 13 is supplied to the wind boxes 8, 9, 10 through the combustion primary air supply pipe 16, and passes through the grate 5, 6, 7 in the combustion chamber 3. To be supplied. The primary air for combustion supplied from below the grate is used for drying and burning the waste 2 on the grate, and also has a grate cooling action and a waste agitation action.
  A secondary combustion region 17 of the waste heat boiler 12 is connected to the outlet of the combustion chamber 3 on the side opposite to the hopper 1. In the combustion chamber 3, a barrier (intermediate ceiling) 11 is provided in the vicinity of the outlet of the combustion chamber 3 for diverting the combustible gas generated from the waste and the combustion gas. The flow is divided into a main flue 20 and a sub flue 21. The combustible gas and the combustion gas divided into the main flue 20 and the sub flue 21 are led to the waste heat boiler 12 where they are mixed and stirred, and the secondary combustion region 17 which is a part of the waste heat boiler 12. The combustion exhaust gas generated by the secondary combustion is recovered by the waste heat boiler 12. After the heat recovery, the combustion exhaust gas discharged from the waste heat boiler 12 is sent to the first dust removing device 18 through the duct 14 where the fly ash contained in the combustion exhaust gas is recovered. The combustion exhaust gas after being dust-removed by the first dust removing device 18 is subjected to neutralization of acid gas by slaked lime and adsorption of dioxins by activated carbon, and is further sent to the second dust removing device 19, where activated carbon and the like are Collected. The combustion exhaust gas that has been dedusted and detoxified by the second dust removing device 19 is attracted by the induction fan 22 and discharged from the chimney 23 into the atmosphere. In addition, as said dust removal apparatuses 18 and 19, dust removal apparatuses, such as a bag filter system, a cyclone system, and an electrostatic dust collection system, can be used, for example.
  In such an apparatus configuration, the present invention blows primary combustion air into the combustion chamber from below the grate, and hot gas is blown into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber. While circulating exhaust gas containing at least a part of exhaust gas discharged from the furnace is blown above the hot gas blowing position or downstream in the gas flow direction, and within the air, circulating exhaust gas, or a mixed gas of air and circulating exhaust gas The combustion control of the waste incinerator is performed by blowing the stirring gas composed of any of the above into the secondary combustion region. In FIG. 1, a furnace having an intermediate ceiling 11 and having a grate inclined is illustrated. However, in the present invention, a furnace or grate having no intermediate ceiling is horizontally arranged. Needless to say, the present invention can also be applied to the furnace provided.
  [Blowing primary air for combustion]
  Here, as described above, the primary combustion air is provided at the lower part of each dry grate 5, combustion grate 6, and post-combustion grate 7 from the blower 13 through the primary air supply pipe 16 for combustion. After being supplied to the air boxes 8, 9, 10, the air is supplied into the combustion chamber 3 through the grate 5, 6, 7. The flow rate of the primary combustion air supplied into the combustion chamber 3 is adjusted by a flow rate control valve 24 provided in the primary combustion air supply pipe 16, and the flow rate supplied to each wind box is The flow rate is adjusted by flow control valves 24a, 24b, 24c, and 24d provided in the supply pipes 16a, 16b, 16c, and 16d, which are branched from the box. Further, the configuration of the wind box and the combustion primary air supply pipe for supplying the combustion primary air is not limited to the illustrated one, and may be appropriately selected depending on the scale, shape, application, etc. of the incinerator.
  [Blowing hot gas]
  The hot gas is blown into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber 3. This is because it is preferable for stabilizing the combustion that the high-temperature gas is blown into a region where a flame exists and a large amount of combustible gas exists. In the grate-type waste incinerator, the region where a large amount of combustible gas exists is from the combustion start region to the main combustion region.
  When the waste is incinerated, water evaporation occurs first, followed by thermal decomposition and partial oxidation reaction, and combustible gas begins to be generated. Here, the combustion start region is a region where combustion of waste starts and combustible gas begins to be generated by thermal decomposition and partial oxidation of the waste. The main combustion region is a region where waste is thermally decomposed, partially oxidized and burned, combustible gas is generated and burned with flame, and combustion with flame is completed (burning This is the area up to the cutting point. In the region after the burn-out point, a char combustion region (soot combustion region) in which solid unburned matter (char) in the waste is combusted is obtained. In the grate-type incinerator, the combustion start area is the upper space of the dry grate, and the main combustion area corresponds to the upper space of the combustion grate.
  By blowing high temperature gas from the combustion start region in the combustion chamber 3 into the main combustion region, a stagnation region or swirl region is formed immediately above the waste layer, and mixing and stirring of the combustible gas generated from the waste is promoted. Therefore, stable combustion is performed. As a result, generation of soot can be suppressed while suppressing generation of harmful substances such as CO, NOx, dioxins and the like. For this reason, the amount of air blown into the entire incinerator can be reduced, and low air ratio combustion can be performed.
  Further, since the high temperature gas is blown directly on the waste layer, it is heated by heat radiation and sensible heat from the high temperature gas, and thermal decomposition of the waste is promoted.
  Here, the temperature of the high-temperature gas blown from the gas blowing port 25 is preferably in the range of 300 to 600 ° C. When a gas of less than 300 ° C. is blown, the temperature in the furnace decreases, combustion becomes unstable, and CO increases. When gas exceeding 600 ° C. is blown, the generation of clinker in the furnace is promoted and there is no economic effect commensurate with high temperature. By setting the temperature of the hot gas in the range of 300 to 600 ° C., a hydrodynamically stable stagnation region is formed near the waste layer in the furnace, and stable combustion is performed. Moreover, it is preferable to use a high-temperature gas containing an oxygen concentration of about 5 to 18%. Thereby, the above-mentioned effect is exhibited more effectively, and the reduction of NOx and the reduction of CO are further promoted.
  As the high-temperature gas having the above gas temperature and oxygen concentration, it is preferable to use return exhaust gas or a mixed gas of return exhaust gas and air. Returned exhaust gas is a part of the exhaust gas discharged from the waste incinerator. Conventionally, returning the exhaust gas to the combustion chamber or the secondary combustion region can utilize the sensible heat or improve gas mixing in the combustion chamber. This is used to improve the combustion state.
  When the return exhaust gas satisfies a predetermined condition, the return exhaust gas may be blown into the furnace as it is, but the temperature of the return exhaust gas may be low and the oxygen concentration may be low. In this case, high-temperature combustion gas such as burner combustion gas or high-temperature air produced by a high-temperature air production apparatus or hot-air furnace is mixed with the return exhaust gas, and the inside of the furnace is formed as a high-temperature gas whose temperature and oxygen concentration satisfy predetermined conditions. Or the return exhaust gas may be heated and blown into the furnace.
  In addition, when the exhaust gas from the secondary combustion region is returned and used, if the return exhaust gas has a sufficiently high temperature and high oxygen concentration, the return exhaust gas is not provided without providing a high-temperature air production device or the like. May be used instead of hot air and mixed with air. Further, as long as the temperature and oxygen concentration of the return exhaust gas from the secondary combustion region satisfy predetermined conditions, the return exhaust gas may be directly blown into the furnace as a high temperature gas.
  As examples of the high-temperature air production apparatus, a heat storage burner, a recuperator, a mixture of air and oxygen with combustion gas from a combustion burner, an oxygen enriched burner, or the like can be used.
  Here, when the return exhaust gas and the high-temperature combustion gas or high-temperature air are mixed by the gas mixing device to prepare the high-temperature gas, the gas mixing device can be used as the ejector device 29. In this case, the high-temperature combustion gas or high-temperature air is guided to the ejector device 29, and this is used as a driving flow to mix while sucking the return exhaust gas and blow it into the combustion chamber 3. In this way, since a blower for deriving the return exhaust gas is not required, the configuration of the apparatus is simplified, and troubles due to dust or the like contained in the return exhaust gas can be reduced.
  In FIG. 1, the hot gas injection port 25 is provided above the dry grate 5 and the combustion grate 6 corresponding to the main combustion region from the combustion start region in the combustion chamber 3. Here, the thermal decomposition reaction of waste occurs at a temperature of about 200 ° C., and is almost completed when the temperature reaches about 400 ° C. Near the waste layer in the furnace by blowing high-temperature gas so that at least a pair of gas blowing ports face the region where the flammable gas is generated and the gas blowing direction is horizontal or downward. A stable combustion is performed by forming a stagnation region that is hydrodynamically stable. In the example shown in FIG. 1, since it corresponds to the rear part of the dry grate 5 and the front part of the combustion grate 6, a gas blowing port 25 is provided at these positions to blow high temperature gas. Depending on the composition and properties of the waste 2, the pyrolysis reaction may be completed at a higher temperature. In this case, a gas blowing port 25 is provided on the rear side (right side in the figure) from the position shown in FIG. 1. It is preferable. Note that the number of the gas inlets 25 or the shape of the outlets can be appropriately selected depending on the scale, shape, application, etc. of the incinerator.
  Further, as shown in FIG. 1, the gas inlet 25 is located at a height not exceeding 50% of the combustion chamber height in each region from the combustion start region to the main combustion region, more preferably 40% of the combustion chamber height. %, Specifically at a height within the range of 0.2 to 1.5 m vertically above the waste layer surface on the grate, or vertically above the grate surface. It is preferable to provide at least a pair of gas outlets facing each other at a height position in the range of 2 m to 2.5 m. As a result, the flame holding effect is exhibited by the high-temperature gas blown from the gas blow-in port 25 immediately above the waste layer in the combustion chamber, so that a high-temperature region (flame) can be established immediately above the waste layer in the furnace. . Therefore, the thermal decomposition of the waste is efficiently performed and the high temperature region is far from the ceiling, so that the degree of burning of the ceiling can be reduced. The combustion chamber height refers to the height of the space where main combustion is performed in each part of the grate, and the height from the grate to the combustion chamber ceiling.
  In FIG. 1, at least a pair of gas blowing ports 25 are provided facing both side surfaces of the combustion chamber 3, and high temperature gas is blown from here. Here, as described above, the gas blowing port 25 is preferably provided so that the gas blowing direction is horizontal or downward.
  The combustible gas generated from the waste usually flows upward. Therefore, if the hot gas blowing direction is upward, the flow of the combustible gas and the hot gas will have the velocity component in the same direction, the effect of blocking the gas flow will be reduced, and the effect of the hot gas blowing will be reduced. To do. On the other hand, if the direction in which the high temperature gas is blown is horizontal or downward, a stagnation region between the rising combustible gas and the high temperature gas is formed, and the substantial residence time of the gas here is increased, so that the combustible gas is increased. As the reaction amount increases, the flame is extended, so the amount of NOx generated decreases. In order to promote such an action, it is preferable to provide the gas blowing port downward. However, if the angle is set too much, the high temperature gas does not reach the entire width direction of the combustion chamber 3 and the local high temperature near the furnace wall. Regions are formed to promote clinker formation and furnace wall burnout. Therefore, it is particularly preferable that the angle is in a downward range of 10 to 20 °. In general, a factor that reduces harmful substances such as dioxins in combustion in an incinerator is said to be 3T. These are temperature, agitation (Turbulence), and residence time (Time). In particular, when high-temperature gas is blown at a high speed, a jet of high-temperature gas entrains the surrounding gas, so that agitation (Turbulence) and residence Time (Time) can be improved, and the space temperature in the incinerator can be made more uniform.
  The hot gas may be blown into the combustion chamber 3 only from one side surface of the combustion chamber 3. Furthermore, you may make it blow in from an intermediate | middle ceiling or a ceiling instead of from the side surface of the combustion chamber 3. FIG. However, in either case, care must be taken to prevent clinker formation and furnace material burning near the ceiling of the combustion chamber.
  Moreover, it is preferable that the high-temperature gas blown from the gas blow-in port 25 is blown into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber at a blow speed of at least 10 m / s. The reason why the blowing speed is 10 m / s or more is to ensure a relative speed of 10 times or more of the average superficial speed (about 1 m / s max) in the furnace. The high-temperature gas blowing rate is performed, for example, by adjusting the mixing ratio of the return exhaust gas.
  As a result, a stable stagnation region can be formed near the waste layer in the furnace, stable combustion is performed, and generation of soot is suppressed while suppressing generation of harmful substances such as CO, NOx, and dioxins. Can be suppressed. For this reason, the amount of air blown into the entire incinerator can be reduced, and low air ratio combustion can be performed.
  Also, the flow rate of the hot gas blown from a plurality of blow nozzles so that the temperature of the primary combustion exhaust gas that has passed through the combustion start region or the main combustion region is higher than the temperature of the primary combustion exhaust gas that has passed through the post-combustion region. Is preferably adjusted. Here, combustion in the combustion chamber of the incinerator is referred to as primary combustion, and the primary combustion exhaust gas that has passed through the combustion start region or the main combustion region refers to a gas that passes through the auxiliary flue 21 in FIG. The primary combustion exhaust gas that has passed through the post-combustion region refers to a gas that passes through the main flue 20 in FIG.
  Waste in the combustion start region or main combustion region by setting the combustion state so that the temperature of the primary combustion exhaust gas passing through the combustion start region or the main combustion region becomes higher than the temperature of the primary combustion exhaust gas passing through the post combustion region Is promoted, and the supply of combustible gas to the secondary combustion region is promoted. In addition, by reducing the temperature of the primary combustion exhaust gas that passes through the post-combustion region having a high oxygen content, it is possible to suppress rapid combustion in the primary combustion region or the secondary combustion region and reduce NOx.
  Here, it is preferable to adjust the temperature of the primary combustion exhaust gas that has passed through the combustion start region or the main combustion region and the temperature of the primary combustion exhaust gas that has passed through the post-combustion region to be within a range of 800 to 1050 ° C. . When the temperature of the primary combustion exhaust gas passing through the combustion start region or the main combustion region exceeds 1050 ° C., the generation of clinker in the furnace is promoted. Further, when the temperature of the primary combustion exhaust gas that has passed through the post-combustion region becomes less than 800 ° C., the temperature in the secondary combustion region decreases, combustion becomes insufficient, and CO increases.
  The primary combustion exhaustGas temperatureIs adjusted by adjusting the flow rate of the hot gas and / or circulating exhaust gas blown from a plurality of blow nozzles. When raising the temperature of the primary combustion exhaust gas that has passed through the combustion start region or the main combustion region, the temperature is adjusted by increasing the flow rate of the hot gas supplied to this region and decreasing the flow rate of the circulating exhaust gas. Further, when the temperature of the primary combustion exhaust gas is lowered, it is adjusted by decreasing the flow rate of the hot gas supplied to this region and increasing the flow rate of the circulating exhaust gas.
  The temperature adjustment of the primary combustion exhaust gas via the post-combustion region is performed in the same manner.
  The primary combustion exhaust gas temperature can also be adjusted by adjusting the oxygen concentration and / or gas temperature of the high-temperature gas blown from a plurality of blown nozzles. When the temperature of the primary combustion exhaust gas passing through the combustion start region or the main combustion region is increased, the temperature is adjusted by increasing the oxygen concentration of the high-temperature gas supplied to this region and increasing the gas temperature. When the temperature of the primary combustion exhaust gas is lowered, the temperature is adjusted by decreasing the oxygen concentration of the high-temperature gas supplied to this region and lowering the gas temperature.
  The temperature adjustment of the primary combustion exhaust gas via the post-combustion region is performed in the same manner.
  Here, it is preferable to adjust the oxygen concentration of the high-temperature gas blown from the plurality of blow nozzles installed in a range of 5 to 18%. This is to ensure the self-maintenance of combustion and the controllability of temperature control in the primary combustion region or the secondary combustion region.
  Moreover, it is preferable that the temperature of the hot gas blown from the plurality of blow nozzles installed is in the range of 300 to 600 ° C. When a gas of less than 300 ° C. is blown, the temperature in the furnace decreases, combustion becomes unstable, and CO increases. When gas exceeding 600 ° C. is blown, the generation of clinker in the furnace is promoted and there is no economic effect commensurate with high temperature. By setting the temperature of the hot gas in the range of 300 to 600 ° C., a hydrodynamically stable stagnation region is formed near the waste layer in the furnace, and stable combustion is performed.
  [Blowing of exhaust gas that contains at least part of the exhaust gas discharged from the incinerator]
  Circulating exhaust gas containing at least a part of exhaust gas or air discharged from the incinerator is blown above the hot gas blowing position in the combustion chamber 3 or downstream in the gas flow direction. In addition, the said gas flow direction downstream means the downstream with respect to the gas flow direction in a furnace. Moreover, the said gas means the combustible gas and combustion exhaust gas which mainly generate | occur | produce in a combustion chamber.
  Here, as the exhaust gas that includes at least a part of the exhaust gas discharged from the incinerator, as shown in FIG. 1, for example, the exhaust gas after being discharged from the incinerator 30 and passing through the first dust removing device 18. Part of the gas (gas temperature: about 150 to 200 ° C., oxygen concentration: about 4 to 8%) or part of the exhaust gas after passing through the second dust removing device 19 (gas Temperature: about 150 to 190 ° C., oxygen concentration: about 4 to 8%). The circulating exhaust gas may be the exhaust gas discharged from the incinerator 30 as it is or may be a mixture of air.
  When the air is mixed with the exhaust gas, the exhaust gas may be mixed while sucking it using an ejector using the mixed air as a driving flow, and may be blown into the rear combustion region in the combustion chamber 3. In this way, since a blower for extracting the exhaust gas is not necessary, the configuration of the apparatus is simplified, and troubles caused by corrosive gas contained in the exhaust gas can be reduced.
  Flame temperature above the combustion region or downstream in the gas flow direction stabilized by blowing high temperature gas in the combustion chamber 3 by blowing the circulating exhaust gas above the hot gas blowing position or downstream in the gas flow direction. And the generation of a high temperature region over a wide range is prevented, and the generation of NOx is more effectively suppressed. Further, by blowing in the circulating exhaust gas having a low oxygen concentration (about 4 to 8%), the region above the hot gas blowing position or the downstream side in the gas flow direction is brought close to the reducing atmosphere, and the generation of NOx is suppressed.
  Here, by blowing the circulating exhaust gas above the gas stagnation region or the gas flow direction downstream region formed by blowing the high temperature gas, the local high temperature region above the stagnation region or downstream in the gas flow direction By suppressing the generation, that is, averaging the temperature distribution and further promoting the agitation in the region, the oxygen concentration distribution can be averaged to achieve further low NOx reduction.
  Further, the circulating exhaust gas inlet 27 for blowing the circulating exhaust gas above the hot gas blowing position or the downstream region in the gas flow direction is located above the hot gas inlet 25 or downstream in the gas flow direction (directly above in the case of FIG. 1). It is preferable to install them at a distance of about 10% of the height of the combustion chamber. This is because the formation of the stable stagnation region and the suppression of the generation of the local high-temperature region are effectively performed to suppress the generation of NOx more significantly.
  However, the circulating exhaust gas inlet 27 and the high temperature gas inlet 25 may be an integrated inlet separated by a single partition. In this case, although the effect of suppressing the generation of NOx is slightly inferior to that in the above case, the construction cost can be reduced with the integrated blow-in port, and the space is advantageously secured.
  The circulation exhaust gas inlet 27 is intended to average the gas temperature distribution and oxygen concentration distribution above the gas stagnation region or downstream region in the gas flow direction formed by the high temperature gas injection. It is not necessary to provide at least a pair so that the gas blowing direction is horizontal or downward.
  [Blowing stirring gas]
  A stirring gas composed of either air, circulating exhaust gas, or a mixed gas of air and circulating exhaust gas is blown into the secondary combustion region.
  Here, it is preferable to install one or a plurality of the stirring gas blowing ports 31 so as to blow the gas in the direction in which the swirling flow is generated in the secondary combustion region 17. By swirling the gas into the secondary combustion region 17, the gas temperature and oxygen concentration distribution in the secondary combustion region 17 can be averaged, the occurrence of a local high temperature region can be suppressed, and further NOx reduction can be achieved. It becomes possible. Furthermore, since the mixing of the combustible component and oxygen is promoted, the stability of combustion is improved, and complete combustion can be achieved, so that it is possible to reduce CO.
  As shown in FIG. 1, the stirring gas includes only the combustion secondary air supplied by the blower 56, a part of the exhaust gas after passing through the first dust removing device 18, or the second dust removing device 19. Either the circulating exhaust gas extracted from a part of the exhaust gas after passing through the gas, or the gas obtained by mixing the secondary air for combustion and the circulating exhaust gas can be used.
  Here, it is preferable to adjust the flow rate of the circulating exhaust gas and / or the stirring gas so that the gas temperature in the secondary combustion region 17 is in the range of 800 to 1050 ° C. When the gas temperature in the secondary combustion region 17 is less than 800 ° C., combustion becomes insufficient and CO increases. Moreover, when the gas temperature in the secondary combustion area | region 17 exceeds 1050 degreeC, the production | generation of clinker in the secondary combustion area | region 17 will be promoted, and NOx will increase further.
  The gas temperature in the secondary combustion region 17 can be increased by reducing the flow rate of the circulating exhaust gas, and the gas temperature in the secondary combustion region 17 can be decreased by increasing the flow rate of the stirring gas. it can.
  Also,For the theoretical amount of oxygen per unit time required for combustion of wasteThe amount of oxygen per unit time supplied by the combustion primary air blown into the combustion chamber 3 from below the grateRatio ofQ1 and the amount of oxygen per unit time supplied by the high-temperature gas blown into any region between the combustion start region and the main combustion region in the combustion chamber 3Ratio ofQ2 and the amount of oxygen per unit time supplied by circulating exhaust gas blown above the hot gas blowing position or downstream in the gas flow directionRatio ofQ3 and the amount of oxygen per unit time supplied by the stirring gas blown into the secondary combustion regionRatio ofQ4 andBelowIt is preferable to blow in so as to satisfy the formulas (1) and (2), more preferably the following formulas (3) and (4).
Q1: Q2: Q3: Q4 = 0.75-1.20: 0.05-0.20: 0.02-0.20: 0.02-0.25 (1)
1.2 ≦ Q1 + Q2 + Q3 + Q4 ≦ 1.5 (2)
Q1: Q2: Q3: Q4 = 0.75-1.1: 0.07-0.15: 0.02-0.15: 0.02-0.25 (3)
1.25 ≦ Q1 + Q2 + Q3 + Q4 ≦ 1.35 (4)
  Here, the theoretical oxygen amount per unit time required for the combustion of the waste is the amount of oxygen required for the combustion per unit mass of the waste determined from the properties and components of the waste put into the combustion chamber. It is determined by the product (Nm3 / hr) of (Nm3 / kg) and the incineration rate (kg / hr) of waste in the incinerator. Q1 is the amount of oxygen per unit time supplied by the combustion primary air supplied from the grate 5, 6, 7 into the combustion chamber 3.Ratio ofIt is adjusted by increasing or decreasing the flow rate of the combustion primary air. Q2 is adjusted by increasing or decreasing the flow rate of the hot gas blown into an arbitrary region between the combustion start region in the combustion chamber 3 and the main combustion region. Q3 is adjusted by increasing or decreasing the flow rate of the circulating exhaust gas blown above the hot gas blowing position in the combustion chamber 3 or downstream in the gas flow direction. Q4 is adjusted by increasing or decreasing the flow rate of the stirring gas blown into the secondary combustion region.
  In the following, Q1 + Q2 + Q3 + Q4 is referred to as λ.
  By setting Q1, Q2, Q3, and Q4 in the range of the above equation, low oxygen ratio combustion (1.2 ≦ λ ≦ 1.5) (that is, low air ratio combustion) is performed in the waste incinerator. Even when it is performed, the generation amount of harmful gases such as CO and NOx can be reduced, and the total amount of exhaust gas discharged from the incinerator can be greatly reduced.
  The distribution ratio to achieve stable low air ratio combustion by suppressing the generation of unburned waste and harmful substances is as follows: Q1: Q2: Q3: Q4 = 0.98: 0.10: 0.12: 0.10, λ = 1.30 As a reference, Q1, Q2, Q3, and Q4 are adjusted within the above range with λ in the range of 1.2 to 1.5 based on the composition and properties of the waste put into the furnace.
  Specific examples of Q1, Q2, Q3, Q4, and λ will be described below.
Q1: Q2: Q3: Q4 = 0.98: 0.10: 0.12: 0.10, λ = 1.30
Q1: Q2: Q3: Q4 = 0.98: 0.12: 0.12: 0.08, λ = 1.30
Q1: Q2: Q3: Q4 = 0.98: 0.14: 0.12: 0.06, λ = 1.30
Q1: Q2: Q3: Q4 = 0.98: 0.10: 0.15: 0.12, λ = 1.35
Q1: Q2: Q3: Q4 = 0.98: 0.10: 0.13: 0.14, λ = 1.35
Q1: Q2: Q3: Q4 = 0.98: 0.10: 0.12: 0.15, λ = 1.35
Q1: Q2: Q3: Q4 = 1.05: 0.10: 0.09: 0.06, λ = 1.30
Q1: Q2: Q3: Q4 = 1.05: 0.10: 0.08: 0.07, λ = 1.30
Q1: Q2: Q3: Q4 = 1.05: 0.12: 0.10: 0.08, λ = 1.35
Q1: Q2: Q3: Q4 = 1.05: 0.12: 0.12: 0.06, λ = 1.35
Q1: Q2: Q3: Q4 = 1.05: 0.14: 0.13: 0.08, λ = 1.40
Q1: Q2: Q3: Q4 = 1.05: 0.14: 0.15: 0.06, λ = 1.40
Q1: Q2: Q3: Q4 = 1.10: 0.05: 0.10: 0.05, λ = 1.30
Q1: Q2: Q3: Q4 = 0.90: 0.10: 0.12: 0.18, λ = 1.30
Q1: Q2: Q3: Q4 = 0.90: 0.10: 0.15: 0.15, λ = 1.30
Q1: Q2: Q3: Q4 = 0.90: 0.12: 0.12: 0.16, λ = 1.30
Q1: Q2: Q3: Q4 = 0.90: 0.15: 0.12: 0.13, λ = 1.30
Q1: Q2: Q3: Q4 = 0.90: 0.12: 0.03: 0.25, λ = 1.30
Q1: Q2: Q3: Q4 = 0.90: 0.15: 0.15: 0.10, λ = 1.30
Q1: Q2: Q3: Q4 = 0.75: 0.15: 0.15: 0.25, λ = 1.30
Q1: Q2: Q3: Q4 = 0.78: 0.12: 0.15: 0.25, λ = 1.30
Q1: Q2: Q3: Q4 = 0.78: 0.15: 0.12: 0.25, λ = 1.30
Q1: Q2: Q3: Q4 = 0.78: 0.15: 0.15: 0.22, λ = 1.30
Q1: Q2: Q3: Q4 = 0.80: 0.10: 0.15: 0.25, λ = 1.30
Q1: Q2: Q3: Q4 = 0.80: 0.12: 0.13: 0.25, λ = 1.30
Q1: Q2: Q3: Q4 = 0.80: 0.15: 0.15: 0.20, λ = 1.30
  Hereinafter, the adjustment criteria for Q1, Q2, Q3, and Q4 will be described.
  [Q1 adjustment criteria]
  Q1 = 0.98 is the standard for drying and burning normal municipal waste and other waste. When burning waste with low ash content or low moisture, such as plastic, Q1 is set to 0.00. Reduce to around 75-0.9 and instead increase Q2.
  [Q2 adjustment criteria]
  To burn normal municipal waste, etc., based on Q2 = 0.1, waste with little ash and moisture, most combustible, such as plastic, or waste with a large volatile content In the case of burning, Q2 is increased. When Q2 is small, the above-described effect of blowing high-temperature gas cannot be obtained sufficiently. If Q2 is increased beyond the above range, low air ratio combustion cannot be achieved, fuel cost for generating high temperature gas increases, the temperature in the combustion chamber becomes excessive, and clinker is generated on the inner wall. NOx increases.
  [Q3, Q4 adjustment criteria]
  First, as standard operating standards for waste incinerators, Q1 and Q2 are determined based on the above standards in consideration of the composition and properties of the waste, and then standard values for Q3 and Q4 are set.
  Here, the combustion state in the combustion chamber is adjusted by adjusting the value of Q3, and the combustion state in the secondary combustion region is adjusted by adjusting the value of Q4. Q3 is adjusted within a range of 0.02 to 0.2 with Q3 = 0.12 as a reference. Q4 is adjusted within a range of 0.02 to 0.25 with Q4 = 0.18 as a reference. Q3 + Q4 is adjusted within a range of 0.15 to 0.4 with Q3 + Q4 = 0.3 as a reference.
  In actual operation of the waste incinerator, even if the operation is based on the standard operation standard, the combustion state in the incinerator may change and the amount of harmful substances in the exhaust gas emitted may fluctuate. Therefore, while maintaining the determined values of Q1 and Q2, adjust either Q3, Q4, or the sum of Q3 and Q4 based on the factors that monitor the situation in the waste incinerator To do. By adopting such a combustion control method, even if the combustion situation in the incinerator changes, it can be adjusted so that the combustion is performed stably, and finally harmful substances in the exhaust gas discharged from the waste incinerator The amount can be easily controlled, and the combustion control system of the incinerator can be simplified.
  Here, as a factor for monitoring the situation in the waste incinerator, for example, the gas temperature in the vicinity of the outlet of the secondary combustion region 17 where secondary combustion of the combustible gas and the combustion gas generated in the combustion chamber 3 is performed. , In gas O₂It is preferable to set one or more of the concentration, the CO concentration in the gas, and the NOx concentration in the gas. Specific combinations of the monitoring factors include, for example, (1) gas temperature, (2) O in gas₂Concentration, (3) Gas temperature and O in gas₂Concentration, (4) gas temperature and gas CO concentration, (5) gas NOx concentration and gas temperature, and (6) gas NOx concentration and gas CO concentration can be used.
  Further, the method of adjusting the Q3 is performed by adjusting the flow rate of the exhaust gas when the circulating exhaust gas blown into the post-combustion region in the combustion chamber 3 is composed only of exhaust gas discharged from the incinerator. In the case where the circulating exhaust gas is, for example, a mixed gas of exhaust gas discharged from an incinerator and air, the amount of air mixed can be adjusted.
  FIG. 2 shows an example of a schematic configuration of the adjusting means 26 when adjusting the amount of air mixed with the exhaust gas as a method of adjusting Q3. The adjusting means 26 shown in FIG. 2 extracts a part of the exhaust gas after passing through the first dust removing device 18 or a part of the exhaust gas after passing through the second dust removing device 19, and passes through the blower 52. It is provided in the middle of a pipe 28 for injecting the circulating exhaust gas from the circulating exhaust gas inlet 27 provided above the hot gas blowing position in the combustion chamber 3 or on the downstream side in the gas flow direction. The adjusting means 26 controls a gas mixing device 50 for mixing exhaust gas and air, an air supply pipe 51 for supplying air to the gas mixing device 50, and an amount of air supplied to the gas mixing device 50. An air amount control device 58.
  The air supply pipe 51 is provided with a blower 56 for taking in air and a flow rate adjusting valve 54 for adjusting the amount of air supplied to the gas mixing device 50. Further, the air amount control device 58 determines the amount of air to be mixed with the exhaust gas based on the measurement signal from the measuring means 59 for measuring the monitoring factor, and controls the flow rate adjusting valve 54 so as to be the amount of air. .
  When the circulating exhaust gas blown above the hot gas blowing position or downstream in the gas flow direction is composed only of the exhaust gas discharged from the incinerator, the opening degree of the damper provided in the middle of the pipe 28 is set. By controlling, the circulating exhaust gas flow rate is adjusted.
  Further, the method of adjusting the Q4 is performed by adjusting the flow rate of the air or the circulating exhaust gas when the stirring gas blown into the secondary combustion region consists of only air or only the circulating exhaust gas. When the agitation gas is a mixed gas of air and circulating exhaust gas, the mixing can be performed by adjusting the amount of air to be mixed or the amount of circulating exhaust gas.
  Tables 1 and 2 show an example of a method for adjusting the values of Q3, Q4 or the sum of Q3 and Q4 in an actual waste incinerator. It shows how to adjust the change in the amount of harmful substances in the exhaust gas when the monitoring factor fluctuates from the reference value, and Q3, Q4, or the sum of Q3 and Q4.
  The stirring gas is blown from the side wall in the vicinity of the inlet of the secondary combustion region 17 so as to form a swirling flow in a direction opposite to the atmosphere gas flow in the post-combustion region on a horizontal plane.
  Here, the gas temperature near the outlet of the secondary combustion region 17, which is a factor for monitoring the situation in the waste incinerator,₂Each reference value of the concentration, the CO concentration in the gas, and the NOx concentration in the gas, and the measuring means thereof are as shown below.
[Standard value]
Gas temperature: 950 ± 50 ° C
O in gas₂Concentration: 5.5 ± 0.5%
CO concentration in gas: 30ppm or less on average
              (Control so that instantaneous value does not exceed 100ppm)
NOx concentration in gas: 100ppm or less
[Measuring means]
Gas temperature: Temperature sensor (thermocouple, radiation thermometer)
O in gas₂Concentration: Oxygen concentration meter
CO concentration in gas: CO concentration meter
NOx concentration in gas: NOx concentration meter
[Table 1]

[Table 2]

  When combustible gas generated by waste and thermal decomposition in an incinerator is combusted within the range of appropriate oxygen concentration and temperature, the most harmful substances such as CO, NOx, DXN (dioxins) are generated. It is suppressed.
  In Table 1, when the gas temperature near the outlet of the secondary combustion region 17 is high (in the case of (1)), combustion in the combustion chamber is suppressed, and as a result, combustion in the secondary combustion region is rapidly performed. Therefore, it is considered that the gas temperature is rising. In this case, the CO concentration and DXN concentration discharged from the incinerator decrease or remain unchanged, but the NOx concentration increases. Therefore, when adjusting only Q3, the amount of oxygen supplied to the combustion chamber is increased by increasing Q3, and the combustion in the combustion chamber is actively performed to optimize the combustion in the secondary combustion region. . When adjusting only Q4, Q4 is decreased, the amount of oxygen supplied to the secondary combustion region is decreased, and combustion in the secondary combustion region is appropriately performed. When adjusting the total value of Q3 + Q4, Q3 is increased, Q4 is decreased, and the total value of Q3 + Q4 is increased or the combustion in the combustion chamber and the secondary combustion region is appropriately performed without change.
  O in gas near the outlet of the secondary combustion region 17₂When the concentration is high (in the case of (2)), the CO concentration and DXN concentration discharged from the incinerator are decreased or unchanged, but the NOx concentration is increased. Therefore, when adjusting only Q3, Q3 is increased to increase the supply amount of oxygen into the combustion chamber, and the consumption of oxygen is increased by actively performing combustion in the combustion chamber. When adjusting only Q4, Q4 is decreased, the amount of oxygen supplied to the secondary combustion region is decreased, and combustion in the secondary combustion region is appropriately performed. When adjusting the total value of Q3 + Q4, Q3 is increased, Q4 is decreased, and the total value of Q3 + Q4 is increased or the combustion in the combustion chamber and the secondary combustion region is appropriately performed without change.
  On the contrary, in the gas near the outlet of the secondary combustion region 17 O₂When the concentration is low (in the case of (3)), the NOx concentration discharged from the incinerator decreases, but the CO concentration and DXN concentration increase or remain unchanged. Therefore, when adjusting only Q3, Q3 is decreased, the dilution rate by the circulating exhaust gas in the combustion chamber is reduced, and the oxygen concentration in the secondary combustion region is increased. When adjusting only Q4, Q4 is increased and the supply amount of oxygen to the secondary combustion region is increased. When adjusting the total value of Q3 + Q4, Q3 is decreased, Q4 is increased, and the total value of Q3 + Q4 is increased so that combustion in the combustion chamber and the secondary combustion region is appropriately performed.
  When the CO concentration in the gas near the outlet of the secondary combustion region 17 is high (in the case of (4)), combustion in the secondary combustion region is insufficient, and unburned combustible gas remains. Conceivable. Therefore, when adjusting only Q3, Q3 is decreased, the temperature in the secondary combustion region is increased, combustion is stabilized, and CO emission is suppressed. When adjusting only Q4, Q4 is increased to increase the amount of oxygen supplied to the secondary combustion region so that combustion in the secondary combustion region is properly performed. The total value of Q3 + Q4 is increased so that combustion in the combustion chamber and the secondary combustion region is properly performed.
  The gas temperature near the outlet of the secondary combustion region 17 is low, and O in the gas₂When the concentration is high (in the case of (5)), the flow rate of the stirring gas is excessive, so that the temperature in the secondary combustion region is lowered and combustion is considered to be unstable. In this case, the CO concentration and DXN concentration discharged from the incinerator increase. Therefore, Q3 is increased or unchanged, Q4 is decreased, and combustion in the secondary combustion region is appropriately performed.
  The gas temperature near the outlet of the secondary combustion region 17 is low, and O in the gas₂When the concentration is low (in the case of (6)), it is considered that combustion in the secondary combustion region is suppressed and the gas temperature is lowered. In this case, the CO concentration and DXN concentration discharged from the incinerator increase. Therefore, Q3 is decreased to increase the temperature in the combustion chamber to increase the amount of inflow of combustible gas into the secondary combustion region, and Q4 is increased to increase the supply amount of oxygen to the secondary combustion region. Make sure to burn properly. The total value of Q3 + Q4 is increased or the combustion in the combustion chamber and the secondary combustion region is appropriately performed without changing.
  When the CO concentration in the gas near the outlet of the secondary combustion region 17 is high and the gas temperature is high (in the case of (7)), combustion in the combustion chamber is incomplete, and combustion in the secondary combustion region is abrupt. Since this is done, the gas temperature is increased, and it is considered that unburned combustible gas remains. In this case, the CO concentration and DXN concentration discharged from the incinerator increase. Therefore, Q3 is increased to lower the temperature in the combustion chamber, and Q4 is increased to lower the temperature of the secondary combustion region while increasing the amount of oxygen supplied to the secondary combustion region, and combustion in the secondary combustion region Make sure that you do it properly.
  When the CO concentration in the gas near the outlet of the secondary combustion region 17 is high and the gas temperature is low (in the case of (8)), the amount of waste gas supplied is reduced and the flow rate of circulating exhaust gas blown into the combustion chamber becomes excessive. For this reason, it is considered that the temperature in the furnace is lowered and combustion is unstable. In this case, the CO concentration and DXN concentration discharged from the incinerator increase. Therefore, Q3 is decreased to increase the furnace temperature and stabilize combustion, and Q4 is increased to increase the amount of oxygen supplied to the secondary combustion region so that combustion in the secondary combustion region is performed properly. To do. The total value of Q3 + Q4 is increased or the combustion in the combustion chamber and the secondary combustion region is appropriately performed without changing.
  When the NOx concentration in the gas near the outlet of the secondary combustion region 17 is high and the gas temperature is high (in the case of (9)), combustion in the combustion chamber is suppressed, and as a result, combustion in the secondary combustion region is abrupt. Therefore, it is considered that the gas temperature rises and the NOx concentration in the gas increases. For this reason, Q3 is increased to lower the temperature in the combustion chamber, the combustion in the combustion chamber is suppressed, Q4 is decreased, the amount of oxygen supplied to the secondary combustion region is decreased, and the secondary combustion region is reduced. Ensure proper combustion. The total value of Q3 + Q4 is increased or the combustion in the combustion chamber and the secondary combustion region is appropriately performed without changing.
  When the NOx concentration in the gas in the vicinity of the outlet of the secondary combustion region 17 is low but the CO concentration is high (in the case of (10)), combustion in the secondary combustion region is insufficient and unburned combustibility Gas is considered to remain. Therefore, Q3 is decreased to increase the temperature in the combustion chamber to increase the inflow amount of combustible gas into the secondary combustion region, and Q4 is increased to increase the supply amount of oxygen to the secondary combustion region. Make sure to burn properly. The total value of Q3 + Q4 is increased so that combustion in the combustion chamber and the secondary combustion region is properly performed.
  When the NOx concentration in the gas near the outlet of the secondary combustion region 17 is low and the CO concentration is low (in the case of (11)), it is considered that the combustion in the furnace is properly performed. In this case, there is no need for adjustment, and the total value of Q3, Q4, Q3 + Q4 is maintained as it is.
  By controlling as described above, it is possible to effectively reduce the amount of harmful substances such as CO, NOx, and DXN discharged from the waste incinerator without performing complicated control.
  Table 3 also shows that in an actual waste incinerator, waste was burned as Q1: Q2: Q3: Q4 = 0.98: 0.10: 0.12: 0.10 and λ = 1.30 as examples. The result of having measured CO density | concentration, NOx density | concentration, and DXN density | concentration in the waste gas discharged | emitted from an incinerator is shown. In Table 3, as Comparative Example 1 and Comparative Example 2, in the waste incinerator according to the prior art, the oxygen amount r1 per unit time supplied by the combustion primary air blown from under the grate, the main combustion region An incinerator in which the oxygen amount r2 per unit time supplied by air blown into the air, the oxygen amount r3 per unit time supplied by air blown into the post-combustion region, and λ ′ = r1 + r2 + r3 are set as shown in Table 2. The result of having measured CO density | concentration, NOx density | concentration, and DXN density | concentration in the waste gas discharged | emitted from the furnace exit of this is shown.
[Table 3]

  As shown in Table 3, in the example, low air ratio combustion (λ = 1.30) can be achieved, and generation of CO, NOx, and DXN is suppressed. On the other hand, in Comparative Example 1, low air ratio combustion cannot be achieved (λ ′ = 1.7), and the amount of NOx generated is large. In Comparative Example 2, when the low air ratio combustion (λ ′ = 1.3) is performed, the amount of NOx generated is reduced, but the generation of CO is large. This is because the combustion state in the furnace becomes unstable, the combustible gas is discharged as CO without being burned, and further unburned parts such as soot are generated, which also increases the amount of dioxins generated. It is thought that.
  Moreover, you may adjust the blowing flow volume of high temperature gas, circulating exhaust gas, and stirring gas using the ratio with respect to the exhaust gas flow volume discharged | emitted from an incinerator. Thereby, the setting and adjustment of a blowing flow volume can be performed simply.
  In addition, when the waste incinerator described above is an ash melting furnace integrated waste incinerator integrated with an ash melting furnace, all or part of the circulating exhaust gas and / or stirring gas described above is exhausted from the ash melting furnace. May be used. Further, when the ash melting furnace is a kiln type ash melting furnace equipped with a kiln hood, the high temperature gas and / or the stirring gas is attracted to all or a part of the kiln hood through the kiln hood. It is also possible to use air heated in a kiln hood. By using the exhaust gas of the ash melting furnace or the air heated in the kiln hood, waste heat can be used effectively, and energy saving can be achieved.
  As described above, according to the present invention, even when low air ratio combustion is performed in a waste incinerator, the stability of combustion is maintained, the occurrence of local high temperature regions is suppressed, and CO, NOx, etc. Disclosed are a waste incinerator combustion control method and a waste incinerator capable of reducing the amount of harmful gas generated. Furthermore, a combustion control method for a waste incinerator and a waste incinerator that can significantly reduce the total amount of exhaust gas discharged from the incinerator and improve the recovery efficiency of waste heat are provided because low air ratio combustion can be performed. .
[Brief description of the drawings]
[0006]
FIG. 1 is a schematic side sectional view showing an embodiment of a waste incinerator according to the present invention.
FIG. 2 is a diagram showing an example of a schematic configuration of air amount adjusting means mixed with exhaust gas according to the present invention.
FIG. 3 is a schematic sectional side view showing an example of a waste incinerator according to the prior art.

Claims (21)

A combustion control method for a grate-type waste incinerator,
The primary air A for combustion is blown into the combustion chamber from below the grate,
Hot gas B is blown into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber,
The circulating exhaust gas C containing at least a part of the exhaust gas discharged from the incinerator is blown above the hot gas B blowing position or downstream in the gas flow direction,
Agitating gas D consisting of either air, circulating exhaust gas, or a mixed gas of air and circulating exhaust gas is blown into the secondary combustion region,
The combustion control method for a waste incinerator, wherein the high-temperature gas B has a temperature in the range of 300 to 600 ° C and an oxygen concentration in the range of 5 to 18%.   2. The combustion control method for a waste incinerator according to claim 1, wherein the circulating exhaust gas C consists only of exhaust gas discharged from the incinerator. The ratio Q1 of the amount of oxygen per unit time supplied by the combustion primary air A to the theoretical amount of oxygen per unit time required for combustion of waste,
A ratio Q2 of the amount of oxygen per unit time supplied by the hot gas B;
A ratio Q3 of oxygen amount per unit time supplied by the circulating exhaust gas C;
The waste incineration according to claim 1 or 2, wherein the ratio Q4 of the amount of oxygen per unit time supplied by the stirring gas D satisfies the following expressions (1) and (2): Furnace combustion control method,
Q1: Q2: Q3: Q4 = 0.75-1.20: 0.05-0.20: 0.02-0.20: 0.02-0.25 (1)
1.2 ≦ Q1 + Q2 + Q3 + Q4 ≦ 1.5 (2). The ratio Q1 of the amount of oxygen per unit time supplied by the combustion primary air A to the theoretical amount of oxygen per unit time required for combustion of waste,
A ratio Q2 of the amount of oxygen per unit time supplied by the hot gas B;
A ratio Q3 of oxygen amount per unit time supplied by the circulating exhaust gas C;
The waste incineration according to claim 1 or 2, wherein the ratio Q4 of the amount of oxygen per unit time supplied by the stirring gas D satisfies the following expressions (3) and (4): Furnace combustion control method,
Q1: Q2: Q3: Q4 = 0.75-1.1: 0.07-0.15: 0.02-0.15: 0.02-0.25 (3)
1.25 ≦ Q1 + Q2 + Q3 + Q4 ≦ 1.35 (4). The hot gas B is blown in an arbitrary region between a height position not exceeding 50% of the combustion chamber height and from the combustion start region to the main combustion region in the combustion chamber in a blowing direction in a range from horizontal to downward 20 °. The combustion control method for a waste incinerator according to any one of claims 1 to 4, wherein the combustion control method is for a waste incinerator. Arbitrary region where the hot gas B extends from the height position within the range of 0.2 to 1.5 m vertically upward from the waste layer surface on the grate to the main combustion region from the combustion start region in the combustion chamber The combustion control method for a waste incinerator according to any one of claims 1 to 4, wherein the air is blown in a blowing direction in a range from horizontal to downward 20 °. The hot gas B is vertically downward 20 from a height position within a range of 0.2 to 2.5 m vertically upward from the grate surface to any region between the combustion start region and the main combustion region in the combustion chamber. The combustion control method for a waste incinerator according to any one of claims 1 to 4, wherein the blowing is performed in a blowing direction in a range of up to 0 °. The hot gas B is blown into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber at a blowing rate of 10 times or more the superficial velocity in the furnace. The combustion control method for a waste incinerator according to any one of claims 7 to 9. The gas temperature in the secondary combustion region is in the range of 800 to 1050 ° C.
  The flow rate of the circulating exhaust gas C is reduced when the gas temperature is raised, and the flow rate of the stirring gas D is adjusted when the gas temperature is lowered. The combustion control method for a waste incinerator according to any one of claims 8 to 9. The combustion control method for a waste incinerator according to any one of claims 1 to 9, wherein the stirring gas D is blown so that a swirling flow is formed in the secondary combustion region. 2. The flow rate of the hot gas B is adjusted so that the temperature of the primary combustion exhaust gas that has passed through the combustion start region or the main combustion region becomes higher than the temperature of the primary combustion exhaust gas that has passed through the post-combustion region. The combustion control method of a waste incinerator according to any one of claims 10 to 10. Increasing the flow rate of the hot gas B when raising the temperature of the primary combustion exhaust gas so that the temperature of the primary combustion exhaust gas passing through the main combustion region and the post-combustion region is in the range of 800 to 1050 ° C., respectively At least one of reducing the flow rate of the circulating exhaust gas C, and at the time of lowering the primary combustion exhaust gas temperature, at least of reducing the flow rate of the hot gas B and increasing the flow rate of the circulating exhaust gas C. It adjusts so that one may be performed, The combustion control method of the waste incinerator as described in any one of Claims 1 thru | or 11 characterized by the above-mentioned. When increasing the temperature of the primary combustion exhaust gas so that the temperature of the primary combustion exhaust gas passing through the main combustion region and the post-combustion region is in the range of 800 to 1050 ° C., respectively, the oxygen concentration of the hot gas B is increased. And at least one of increasing the temperature, and at the time of decreasing the primary combustion exhaust gas temperature, at least one of decreasing the oxygen concentration of the hot gas B and decreasing the temperature is performed. It adjusts, The combustion control method of the waste incinerator as described in any one of Claims 1 thru | or 11 characterized by the above-mentioned. Combustion primary air blowing means for blowing the combustion primary air A from below the grate into the combustion chamber;
High-temperature gas blowing means for blowing high-temperature gas B having a temperature in the range of 300 to 600 ° C. and an oxygen concentration in the range of 5 to 18% into an arbitrary region between the combustion start region and the main combustion region in the combustion chamber. When,
Circulating exhaust gas blowing means for blowing circulating exhaust gas C containing at least a part of the exhaust gas discharged from the incinerator above the hot gas B blowing position or downstream in the gas flow direction;
Grate-type disposal characterized by comprising stirring gas blowing means for blowing a stirring gas D consisting of either air, circulating exhaust gas, or a mixed gas of air and circulating exhaust gas into the secondary combustion region Incinerator. The fire nozzle according to claim 14, characterized in that the hot gas B blowing nozzle is provided at a height not exceeding 50% of the height of the combustion chamber in a blowing direction ranging from horizontal to 20 ° downward. Lattice waste incinerator. The hot gas B blowing nozzle is provided at a height position within a range of 0.2 to 1.5 m vertically upward from the waste layer surface on the grate in a blowing direction ranging from horizontal to 20 ° downward. The grate-type waste incinerator according to claim 14. The hot gas B blowing nozzle is provided at a height position in the range of 0.2 to 2.5 m vertically upward from the grate surface in a blowing direction in the range of 20 ° downward from the horizontal. The grate-type waste incinerator according to claim 14. The grate-type disposal according to any one of claims 14 to 17, wherein a nozzle for blowing a stirring gas D is provided so that a swirling flow is formed in the secondary combustion region. Incinerator. It is provided with means capable of adjusting the flow rate of the high temperature gas B so that the temperature of the primary combustion exhaust gas passing through the combustion start region or the main combustion region becomes higher than the temperature of the primary combustion exhaust gas passing through the post combustion region. The grate-type waste incinerator according to any one of claims 14 to 18. Provided with means capable of adjusting the flow rate of the hot gas B and / or the circulating exhaust gas C so that the temperature of the primary combustion exhaust gas passing through the main combustion region and the post-combustion region is in the range of 800 to 1050 ° C., respectively. The grate-type waste incinerator according to any one of claims 14 to 19, characterized in that Provided with means capable of adjusting the oxygen concentration and / or gas temperature of the hot gas B so that the temperature of the primary combustion exhaust gas passing through the main combustion region and the post-combustion region is in the range of 800 to 1050 ° C., respectively. The grate-type waste incinerator according to any one of claims 14 to 19, characterized in that

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