JP2005331204A - Exhaust gas denitration method in waste incinerator - Google Patents

Exhaust gas denitration method in waste incinerator Download PDF

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JP2005331204A
JP2005331204A JP2004151913A JP2004151913A JP2005331204A JP 2005331204 A JP2005331204 A JP 2005331204A JP 2004151913 A JP2004151913 A JP 2004151913A JP 2004151913 A JP2004151913 A JP 2004151913A JP 2005331204 A JP2005331204 A JP 2005331204A
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furnace
exhaust gas
reducing agent
rotary kiln
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Koji Sano
幸治 佐野
Shigeru Morishita
茂 森下
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Nippon Steel Corp
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Sumitomo Metal Industries Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To apply a conventional exhaust gas denitration method of a type wherein a reducing agent is sprayed into exhaust gas to a rotary kiln type rotary furnace. <P>SOLUTION: In this exhaust gas denitration method in the rotary kiln type rotary furnace, the reducing agent is sprayed to a position wherein interference with burner flame is reduced from the front face of a rotary kiln 1 into the furnace. Thereby, in the rotary kiln type rotary furnace, nitrogen oxide is reduction-reacted inside the furnace, and excellent denitration effect can be obtained about nitrogen oxide in the exhaust gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、ロータリーキルン型のたとえば廃棄物焼却炉において、炉内に尿素水又はアンモニア水等の還元剤を噴霧し、炉内にて窒素酸化物を還元させる脱硝方法に関するものである。   The present invention relates to a denitration method in which, in a rotary kiln type, for example, a waste incinerator, a reducing agent such as urea water or ammonia water is sprayed in the furnace and nitrogen oxides are reduced in the furnace.

廃棄物焼却炉にて雑芥、汚泥、廃油等の廃棄物を焼却する際には、窒素酸化物が発生するため、排ガス中の窒素酸化物を低減する必要が生じる。また、大気汚染防止法・ダイオキシン法といった大気関連法規には設備における排出ガス濃度が規制されており、その規制値を遵守する必要がある。   When waste such as garbage, sludge, and waste oil is incinerated in a waste incinerator, nitrogen oxides are generated, so that it is necessary to reduce nitrogen oxides in exhaust gas. In addition, air-related laws and regulations such as the Air Pollution Control Law and Dioxin Law regulate the exhaust gas concentration in equipment, and it is necessary to comply with those regulations.

この排ガス中の窒素酸化物を除去する方法として、
ａ）排ガス中に尿素水やアンモニア水等の還元剤を噴霧して窒素酸化物を還元除去する方法、
ｂ）窒素酸化物を還元除去するために還元触媒を充填した排ガス脱硝塔を設置する方法、ｃ）排ガス系に排ガス減温設備を設置し、排ガス温度を低下させて窒素酸化物の二次生成を抑制する方法、が挙げられる。 As a method of removing nitrogen oxides in this exhaust gas,
a) A method of reducing and removing nitrogen oxides by spraying a reducing agent such as urea water or ammonia water in exhaust gas,
b) Method of installing an exhaust gas denitration tower filled with a reduction catalyst to reduce and remove nitrogen oxides, c) Secondary exhaust gas nitrogen reduction by installing exhaust gas temperature reduction equipment in the exhaust gas system and lowering the exhaust gas temperature The method of suppressing this is mentioned.

これらの方法のうち、ａ）の技術としては、排ガス配管中に還元剤を噴霧する方法が一般的であるが、炉内に直接噴霧する事例もある。
炉内への噴霧例としては、流動床炉の炉内側面から尿素水やアンモニア水等の還元剤を噴霧することで、窒素酸化物を窒素ガスに還元除去する方法が提案されている。
特開平０５−３３２５２１号公報 Among these methods, the technique of a) is generally a method of spraying a reducing agent into the exhaust gas pipe, but there is also a case of spraying directly into the furnace.
As an example of spraying into the furnace, a method of reducing and removing nitrogen oxides into nitrogen gas by spraying a reducing agent such as urea water or ammonia water from the inner surface of the fluidized bed furnace has been proposed.
JP 05-332521 A

また、炉直後に噴霧する事例としては、セメントプラントのロータリーキルンにおいて、排ガスに対向してロータリーキルンの後端から尿素水やアンモニア水を噴霧することで、窒素酸化物を窒素ガスに還元処理する方法が提案されている。
特開平０９−２０６５５２号公報 As an example of spraying immediately after the furnace, in a rotary kiln of a cement plant, there is a method of reducing nitrogen oxides to nitrogen gas by spraying urea water or ammonia water from the rear end of the rotary kiln facing the exhaust gas. Proposed.
Japanese Patent Laid-Open No. 09-206552

ｂ）の技術としては、炉後段の排ガス系に脱硝塔を設置する方法が提案され、また、ｃ）の技術とあわせたものとして、電気集塵機の後段に脱硝塔、減温塔を設置し、水噴霧による温度調整後バグフィルターを設置する排ガス処理方法が提案されている。
特開２０００−８４５０９０号公報 特開２０００−２６２８５３号公報 As a technique of b), a method of installing a denitration tower in the exhaust gas system at the latter stage of the furnace is proposed, and as a technique in combination with the technique of c), a denitration tower and a temperature reducing tower are installed in the latter stage of the electrostatic precipitator, An exhaust gas treatment method in which a bag filter is installed after temperature adjustment by water spray has been proposed.
JP 2000-845090 A JP 2000-262853 A

しかしながら、ａ）の排ガス中に還元剤を噴霧する方法では、噴霧する還元剤溶液の水分によって排ガス中のダストが配管壁面に付着するという問題や、還元剤噴霧設備にダストが付着するという問題が発生する。   However, in the method of spraying the reducing agent into the exhaust gas of a), there is a problem that dust in the exhaust gas adheres to the pipe wall surface due to moisture of the reducing agent solution to be sprayed, and a problem that dust adheres to the reducing agent spraying equipment. Occur.

また、特許文献１に記載された炉内に還元剤を噴霧する技術は、流動床炉の様に炉壁面が固定されている場合は噴霧装置の設置が可能であるが、ロータリーキルン型の回転炉では、炉の回転により焼却対象物が噴霧装置と接触して噴霧装置に障害を与えるため、炉内壁面に噴霧装置を設置することは困難である。   The technique for spraying the reducing agent in the furnace described in Patent Document 1 can install a spray device when the furnace wall surface is fixed like a fluidized bed furnace, but a rotary kiln type rotary furnace. Then, since the incineration object contacts with the spraying device due to the rotation of the furnace and impedes the spraying device, it is difficult to install the spraying device on the inner wall surface of the furnace.

また、特許文献２に記載されたセメントプラントのロータリーキルンのように、炉内を通過する排ガスの流れ方向と焼却物の流れが反対の、対向流式のロータリーキルンの後端から炉内に向かって還元剤を吹き込む場合には、炉内を通過してきた飛灰の多い排ガスに対して還元剤を吹き込むことになるため、炉内からの飛灰により噴霧ノズルが閉塞し、また、還元剤の水分により排ガス配管の内壁に飛灰が付着するという問題が発生する。   Moreover, like the rotary kiln of the cement plant described in Patent Document 2, the flow direction of the exhaust gas passing through the furnace and the flow of the incinerated product are opposite, and the reduction is performed from the rear end of the counterflow rotary kiln toward the furnace. When the agent is blown in, the reducing agent is blown into the exhaust gas containing a lot of fly ash that has passed through the furnace, so the spray nozzle is blocked by the fly ash from the furnace, and the moisture of the reducing agent There arises a problem that fly ash adheres to the inner wall of the exhaust gas pipe.

また、ｂ）ｃ）の技術では、既存設備に脱硝塔や減温塔を設置する必要があり、大規模な排ガス配管のレイアウト変更や設備投資を要する等の問題が生じる。   In the technique of b) and c), it is necessary to install a denitration tower and a temperature reduction tower in the existing equipment, which causes problems such as a large layout change of exhaust gas piping and capital investment.

本発明が解決しようとする問題点は、排ガス中に還元剤を噴霧する方式の従来の排ガス脱硝方法をロータリーキルン型の回転炉に適用する場合には、（１）炉内壁面に噴霧装置を設置することができないという点、また、（２）炉の後端から還元剤を噴霧する場合には、炉体の長さによっては、還元剤と接触する排ガスの温度が８００℃未満になって良好な還元反応が得られず、また、還元剤溶液の水分によって排ガス中のダストが還元剤噴霧設備に付着するという点である。   Problems to be solved by the present invention are as follows. When applying a conventional exhaust gas denitration method of spraying a reducing agent in exhaust gas to a rotary kiln type rotary furnace, (1) installing a spray device on the inner wall of the furnace (2) When the reducing agent is sprayed from the rear end of the furnace, depending on the length of the furnace body, the temperature of the exhaust gas in contact with the reducing agent is preferably less than 800 ° C. The reduction reaction is not obtained, and the dust in the exhaust gas adheres to the reducing agent spraying equipment due to the moisture of the reducing agent solution.

前述のように、排ガス配管中に尿素水やアンモニア水等の還元剤を噴霧することで、下記化学式１に示したような還元反応をおこさせて、窒素酸化物を窒素ガスとなす排ガスの脱硝方法が一般的に実施されている。   As described above, denitration of exhaust gas in which nitrogen oxide is converted into nitrogen gas by causing a reduction reaction as shown in the following chemical formula 1 by spraying a reducing agent such as urea water or ammonia water into the exhaust gas pipe. The method is commonly practiced.

Figure 2005331204
Figure 2005331204

一方、尿素水やアンモニア水等の還元剤は、雰囲気温度が８００℃以上（〜１０００℃）で噴霧するのが還元反応性の点から望ましいことが一般に知られている。また、廃棄物処理法において、廃棄物焼却炉は炉内温度が８００℃以上で２秒以上滞留させる構造とする基準が設けられている。   On the other hand, it is generally known that a reducing agent such as urea water or ammonia water is preferably sprayed at an atmospheric temperature of 800 ° C. or higher (˜1000 ° C.) from the viewpoint of reduction reactivity. Further, in the waste treatment method, there is provided a standard in which the waste incinerator has a structure in which the temperature in the furnace is 800 ° C. or more and is retained for 2 seconds or more.

従って、ロータリーキルン型の廃棄物焼却炉のように還元剤の噴霧場所を炉内壁面に確保することが出来ない場合には、脱硝に際し、炉内を還元剤の反応場所として活用可能ではあるものの、雰囲気温度が８００℃〜１０００℃の温度域を狙って還元剤を噴霧する必要があるため、その噴霧位置が問題となる。   Therefore, when it is not possible to secure the spraying place of the reducing agent on the wall surface of the furnace as in the rotary kiln type waste incinerator, the inside of the furnace can be used as the reducing agent reaction place when denitrating, Since the reducing agent needs to be sprayed aiming at a temperature range of 800 ° C. to 1000 ° C., the spray position becomes a problem.

そして、その際、１）炉内に吹き込む還元剤の噴霧流がバーナ火炎と接触すると、下記化学式２に示したように、バーナ火炎により還元剤が燃焼して、逆に窒素酸化物が増加する。また、２）炉内に投入された焼却対象物に還元剤がかかって焼却対象物と共に還元剤が燃焼すると、排ガス中の窒素酸化物との還元能力をなくしてしまう。このようなことから、噴霧位置の選定は極めて重要である。   At that time, 1) When the spray flow of the reducing agent blown into the furnace comes into contact with the burner flame, as shown in the following chemical formula 2, the reducing agent burns by the burner flame, and conversely, nitrogen oxides increase. . Moreover, 2) When a reducing agent is applied to the incineration object put into the furnace and the reducing agent burns together with the incineration object, the ability to reduce nitrogen oxides in the exhaust gas is lost. For this reason, the selection of the spray position is extremely important.

Figure 2005331204
Figure 2005331204

本発明に係る回転炉における排ガス脱硝方法は、かかる観点に基づいてなされたものであり、
ロータリーキルン型の回転炉のように還元剤の噴霧場所を炉内壁面に確保することが出来ない場合であっても、炉内に噴霧する還元剤の反応性を良好ならしめ、脱硝塔の新設や排ガス配管のレイアウト変更を必要としないようにするため、
バーナ火炎との干渉を減じる位置に、
ロータリーキルンの前面から炉内に向けて還元剤を噴霧することを最も主要な特徴とし、本発明方法を適用する前記回転炉としては、操業中における炉内温度が８００℃以上である箇所を含む回転炉、たとえば廃棄物焼却炉などがある。 The exhaust gas denitration method in the rotary furnace according to the present invention is made based on this viewpoint,
Even if it is not possible to secure the spraying place of the reducing agent on the wall surface of the furnace as in the rotary kiln type rotary furnace, the reactivity of the reducing agent sprayed in the furnace is improved, and a new denitration tower is installed. In order not to change the layout of exhaust gas piping,
In a position that reduces interference with the burner flame,
The main feature is that the reducing agent is sprayed from the front of the rotary kiln into the furnace, and the rotary furnace to which the method of the present invention is applied includes a rotation including a place where the furnace temperature during operation is 800 ° C. or higher. There are furnaces, such as waste incinerators.

本発明において、バーナ火炎との干渉を減じる位置とは、還元剤を噴霧したことによる還元反応によって還元される窒素酸化物量が、噴霧した還元剤がバーナ火炎等に接触して燃焼することで生成される窒素酸化物量よりも多くなるように、還元剤を噴霧可能な位置を言い、この還元剤を噴霧する位置がバーナ設置位置より炉体の上方であれば、バーナ火炎との干渉を効果的に減じることができる。   In the present invention, the position where the interference with the burner flame is reduced is that the amount of nitrogen oxides reduced by the reduction reaction caused by spraying the reducing agent is generated when the sprayed reducing agent comes into contact with the burner flame and burns. This refers to the position where the reducing agent can be sprayed so that the amount of nitrogen oxide is increased. If the position where the reducing agent is sprayed is above the furnace body from the burner installation position, interference with the burner flame is effective. Can be reduced to

図５は還元剤として尿素水やアンモニア水を噴霧した場合に、還元された窒素酸化物量及び燃焼により酸化されて生成された窒素酸化物量と、還元剤の反応率を示したものである。たとえば還元剤として尿素水を使用した場合の還元反応は、太い実線で示したように、尿素水の反応率が上昇するほど生成される窒素酸化物量は多くなり、尿素水がバーナ火炎と全く接触しない場合（還元剤反応率が１００％）には、前記化学式１で示したように、尿素水１ｍｏｌに対して３／２ｍｏｌの窒素酸化物が生成される（図５中の●印）。   FIG. 5 shows the amount of reduced nitrogen oxides, the amount of nitrogen oxides produced by oxidation by combustion, and the reaction rate of the reducing agent when urea water or ammonia water is sprayed as the reducing agent. For example, when urea water is used as the reducing agent, as shown by the thick solid line, the amount of nitrogen oxide generated increases as the reaction rate of urea water increases, and urea water is completely in contact with the burner flame. When not performed (reducing agent reaction rate is 100%), as shown in the chemical formula 1, 3/2 mol of nitrogen oxides are generated with respect to 1 mol of urea water (circles in FIG. 5).

一方、噴霧された尿素水がバーナ火炎に接触して燃焼する場合の酸化反応は、太い破線で示したように、燃焼する尿素水量が多くなるほど生成される窒素酸化物量は多くなり、尿素水がバーナ火炎によって全て燃焼した場合（還元剤反応率が０％）には、前記化学式２で示したように、尿素水１ｍｏｌに対して２ｍｏｌの窒素酸化物が生成される（図５中の○印）。   On the other hand, in the oxidation reaction when the sprayed urea water is in contact with the burner flame and burned, as the amount of urea water to be burned increases, the amount of nitrogen oxide generated increases, When all of the fuel is burned by the burner flame (reducing agent reaction rate is 0%), as shown in the chemical formula 2, 2 mol of nitrogen oxides are generated with respect to 1 mol of urea water (marked with ○ in FIG. 5). ).

同様に、還元剤としてアンモニア水を使用した場合の結果も図５に示したが、アンモニア水を使用した場合の還元反応は、細い実線で示したように、アンモニア水の反応率が上昇するほど生成される窒素酸化物量は多くなり、アンモニア水がバーナ火炎と全く接触しない場合（還元剤反応率が１００％）には、下記化学式３で示すように、アンモニア水１ｍｏｌに対して７／８ｍｏｌの窒素酸化物が生成される（図５中の■印）。   Similarly, the results when ammonia water is used as the reducing agent are also shown in FIG. 5, but the reduction reaction when ammonia water is used increases the reaction rate of the ammonia water as shown by the thin solid line. When the amount of generated nitrogen oxides increases and ammonia water does not come into contact with the burner flame at all (reducing agent reaction rate is 100%), as shown by the following chemical formula 3, Nitrogen oxide is produced (marked with ■ in FIG. 5).

Figure 2005331204
Figure 2005331204

一方、噴霧されたアンモニア水がバーナ火炎に接触して燃焼する場合の酸化反応は、細い破線で示したように、燃焼するアンモニア水量が多くなるほど生成される窒素酸化物量は多くなり、アンモニア水がバーナ火炎によって全て燃焼した場合（還元剤反応率が０％）には、下記化学式４で示すように、アンモニア水１ｍｏｌに対して１ｍｏｌの窒素酸化物が生成される（図５中の□印）。   On the other hand, the oxidation reaction in the case where the sprayed ammonia water burns in contact with the burner flame, as shown by the thin broken line, the more the amount of ammonia water to be burned, the more nitrogen oxide is generated, When all are burned by the burner flame (reducing agent reaction rate is 0%), 1 mol of nitrogen oxide is generated per 1 mol of aqueous ammonia as indicated by the following chemical formula 4 (□ in FIG. 5). .

Figure 2005331204
Figure 2005331204

従って、還元剤の噴霧位置は、還元反応を示す前記実線と酸化反応を示す前記破線の交点が示す還元剤の反応率以上、たとえば還元剤が尿素水やアンモニア水の場合には５７．１％以上となる位置であれば、バーナの設置位置よりも上方でも下方から噴霧しても良く、また、バーナ先端より炉内側の位置でも炉外側の位置から噴霧しても良い。この還元剤の噴霧位置は、炉に対するバーナの設置位置によっても変化する。   Accordingly, the spray position of the reducing agent is not less than the reaction rate of the reducing agent indicated by the intersection of the solid line indicating the reduction reaction and the broken line indicating the oxidation reaction, for example, 57.1% when the reducing agent is urea water or ammonia water. As long as the position is as described above, spraying may be performed from above or below the burner installation position, or from the position inside the furnace or from the position outside the furnace from the burner tip. The spray position of the reducing agent also varies depending on the position of the burner installed with respect to the furnace.

すなわち、本発明に係る回転炉における排ガス脱硝方法では、吹き込む還元剤の噴霧流がバーナ火炎に可及的に直接接触しない様、ロータリーキルンの前面から炉内に向けて尿素水やアンモニア水などの還元剤を噴霧することにより、炉内にて前述の化学式１や化学式３で示した還元反応が起こり、たとえば廃棄物の炉内燃焼により発生した窒素酸化物に対して良好な脱硝効果を得ることができるようになる。また、噴霧設備（ノズル等）に対する飛灰の影響（ダスト付着）や熱影響を緩和できるメリットもある。   That is, in the exhaust gas denitration method in a rotary furnace according to the present invention, reduction of urea water, ammonia water, or the like from the front of the rotary kiln toward the furnace so that the spray flow of the reducing agent to be injected does not directly contact the burner flame as much as possible. By spraying the agent, the reduction reaction shown in Chemical Formula 1 or Chemical Formula 3 described above occurs in the furnace, and for example, a good denitration effect can be obtained for nitrogen oxides generated by combustion of waste in the furnace. become able to. In addition, there is an advantage that the influence (dust adhesion) and thermal influence of fly ash on the spray equipment (nozzle, etc.) can be reduced.

このように、本発明では、バーナ火炎との干渉を減じる位置に、ロータリーキルン型の回転炉のロータリーキルンの前面から炉内に向けて還元剤を噴霧することにより、炉内容積を還元剤の反応場所として最大限活用できるため、コンパクトな設備レイアウトが可能となり安価な設備にて排ガスの脱硝が可能となる。   As described above, in the present invention, the reducing agent is sprayed from the front surface of the rotary kiln of the rotary kiln type rotary kiln into the furnace at a position where interference with the burner flame is reduced, thereby reducing the reactor volume to the reaction site of the reducing agent. As a result, a compact facility layout is possible, and exhaust gas denitration is possible with inexpensive facilities.

本発明に係る回転炉における排ガス脱硝方法を適用する炉は、ロータリーキルン型であって、還元剤を噴霧する炉内の雰囲気温度が８００℃以上の炉であれば、並行流式であっても、対向流式であっても良い。   The furnace to which the exhaust gas denitration method in the rotary furnace according to the present invention is applied is a rotary kiln type, and if the atmospheric temperature in the furnace spraying the reducing agent is a furnace of 800 ° C. or higher, even if it is a parallel flow type, It may be a counter flow type.

本発明では、ロータリーキルン型の回転炉において、ロータリーキルンの前面から炉内のバーナ火炎との干渉を減じる位置に向けて尿素水又はアンモニア水等の還元剤を吹込むことにより、炉内にて窒素酸化物を還元反応させ、排ガス中の窒素酸化物について良好な脱硝効果を得ることができる。また、既存の設備に脱硝塔や減温塔を設置する必要がなくなり、大規模なレイアウト変更や設備投資を要する等の問題も回避できる。さらに、還元剤の噴霧設備（ノズル）の飛灰による閉塞も緩和され、設備の約３ヶ月間の長期運転も可能となる。   In the present invention, in a rotary kiln type rotary furnace, nitrogen oxides are oxidized in the furnace by blowing a reducing agent such as urea water or ammonia water from the front of the rotary kiln toward a position where interference with the burner flame in the furnace is reduced. A good denitration effect can be obtained with respect to nitrogen oxides in exhaust gas by subjecting the product to a reduction reaction. In addition, it is not necessary to install a denitration tower or a temperature reduction tower in the existing equipment, and problems such as a large-scale layout change and equipment investment can be avoided. Furthermore, the blockage of the reducing agent spraying equipment (nozzles) due to fly ash is alleviated, and the equipment can be operated for a long period of about three months.

以下、本発明を実施するための最良の形態について、図１〜図４を用いて説明する。
図１〜図４の例では、雑芥、汚泥、廃油等を焼却処理する並行流式のロータリーキルン型廃棄物焼却炉において、焼却炉から発生する排ガス中の窒素酸化物を除去する方法について説明する。 Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.
1-4, a method for removing nitrogen oxides in exhaust gas generated from an incinerator in a parallel-flow rotary kiln type waste incinerator that incinerates garbage, sludge, waste oil, and the like will be described. .

図１は本発明方法を実施する設備のフローを示した図で、１は炉内を通過する排ガスの流れ方向と焼却物の流れが並行の、並行流式のロータリーキルン、２は前記ロータリーキルン１の前面におけるたとえば軸中心位置に設けられたバーナ、３は前記ロータリーキルン１の前面から炉内に汚泥を供給すべく配置された汚泥供給シュート、４は廃熱ボイラー、５は乾式電気集塵機、６は誘引ファン、７は煙突を示す。なお、図１中の８は前記汚泥供給シュート３にピット９内の汚泥を供給する天井クレーンを示す。   FIG. 1 is a diagram showing a flow of equipment for carrying out the method of the present invention. 1 is a parallel flow type rotary kiln in which the flow direction of exhaust gas passing through the furnace and the flow of incineration are parallel, and 2 is the rotary kiln 1. For example, a burner provided at the axial center position on the front surface, 3 is a sludge supply chute arranged to supply sludge from the front surface of the rotary kiln 1 into the furnace, 4 is a waste heat boiler, 5 is a dry electrostatic precipitator, and 6 is an inducement A fan 7 indicates a chimney. 1 denotes an overhead crane for supplying the sludge in the pit 9 to the sludge supply chute 3.

前記構成の廃棄物焼却設備では、ロータリーキルン１の前面側に設けられた汚泥供給シュート３からロータリーキルン１内に投入された汚泥は、バーナ２の燃焼熱等によりロータリーキルン１内にて８００℃以上で焼却処理され、後端より排出される。   In the waste incinerator having the above-described configuration, the sludge introduced into the rotary kiln 1 from the sludge supply chute 3 provided on the front side of the rotary kiln 1 is incinerated at 800 ° C. or higher in the rotary kiln 1 by the combustion heat of the burner 2 or the like. It is processed and discharged from the rear end.

また、図１に示した例ではロータリーキルン１、廃熱ボイラー４、電気集塵機５間の距離が短く、かつ、排ガス温度は廃熱ボイラー４の前方では３００℃以下にまで低下しているため、尿素水やアンモニア水等の還元剤を噴霧脱硝する場所が制限される。   In the example shown in FIG. 1, the distance between the rotary kiln 1, the waste heat boiler 4 and the electric dust collector 5 is short, and the exhaust gas temperature is lowered to 300 ° C. or less in front of the waste heat boiler 4. The place where spraying denitration of a reducing agent such as water or ammonia water is limited.

試験的に、前述の先行技術文献２のように、ロータリーキルン１の後端にて下記の条件で尿素水を噴霧したところ、排ガス中の脱硝効果は確認できたものの（表１のケースｂ〜ｄ参照）、還元剤噴霧による水分が飛灰と結合し、２〜３日でロータリーキルン１の直後に設置している廃熱ボイラー４の伝熱管４ａに、図２に示したように、ダスト１０が付着成長して蒸気回収量が低下するという弊害を引き起こした（表１のケースｄ参照）。   As a test, when urea water was sprayed under the following conditions at the rear end of the rotary kiln 1 as in the above-mentioned prior art document 2, denitration effect in exhaust gas was confirmed (cases b to d in Table 1). As shown in FIG. 2, dust 10 is attached to the heat transfer pipe 4a of the waste heat boiler 4 that is installed immediately after the rotary kiln 1 in 2 to 3 days. Adhesive growth caused a negative effect that the steam recovery amount decreased (see case d in Table 1).

また、廃熱ボイラー４の後方にて尿素水等の還元剤を噴霧しても、排ガス温度が低いために窒素酸化物の良好な還元反応が得られなかった。更に、設備面では、新たに脱硝塔や減温塔を排ガス系に追加設置することは設備コストの増大を招き、コスト増となる。   Further, even when a reducing agent such as urea water was sprayed behind the waste heat boiler 4, a good reduction reaction of nitrogen oxides could not be obtained because the exhaust gas temperature was low. Furthermore, in terms of equipment, newly installing a denitration tower or a temperature reducing tower in the exhaust gas system increases the equipment cost and increases the cost.

（試験設備：図３参照）
１．並行流式のロータリーキルン：炉内径３．９ｍ
２．バーナ：ロータリーキルンの前面におけるほぼ軸心位置に設置（図４（ａ）のイメージ）。
３．還元剤噴霧ノズル：バーナの約１．０ｍ上方の位置より時計回りに４５°回転した位置。ノズル先端はバーナ先端より０．５ｍ炉外側の位置。 (Test equipment: see Fig. 3)
1. Parallel flow type rotary kiln: Furnace inner diameter 3.9m
2. Burner: Installed at approximately the axial center position on the front of the rotary kiln (image in FIG. 4A).
3. Reducing agent spray nozzle: A position rotated 45 ° clockwise from a position approximately 1.0 m above the burner. The nozzle tip is located 0.5m outside the burner tip.

（試験条件）
１．先ず、尿素水の吹き込みをしない状態で、排ガス量、温度、ＮＯｘ濃度を測定（ケースａ）。
２．次に、スプレー水量を５．０リットル／分、エアー圧力を３．０ｋｇ／ｍ2に調整した後、尿素水の送り量を１００％（ケースｂ）、６２．５％（ケースｃ）、３０％（ケースｄ）で吹き込み、排ガス量、温度、ＮＯｘ濃度を測定。 (Test conditions)
1. First, the amount of exhaust gas, temperature, and NOx concentration are measured without urea water being blown (case a).
2. Next, after adjusting the spray water amount to 5.0 liters / minute and the air pressure to 3.0 kg / m 2 , the feed amount of urea water is 100% (case b), 62.5% (case c), 30 % (Case d) and measure the amount of exhaust gas, temperature, and NOx concentration.

Figure 2005331204
Figure 2005331204

次に、本発明に係る排ガスの脱硝方法について説明する。
図１に示すようにロータリーキルン１の前面に、タンク１２内の尿素水やアンモニア水等の還元剤をロータリーキルン１内に噴霧する還元剤噴霧ノズル１１を設置し、かつ、バーナ２の火炎に可及的に直接触れないよう、尿素水等の還元剤の炉内への噴霧位置を調整することにより、ロータリーキルン１内での排ガス中窒素酸化物の脱硝反応を可能とした。 Next, the exhaust gas denitration method according to the present invention will be described.
As shown in FIG. 1, a reducing agent spray nozzle 11 for spraying a reducing agent such as urea water or ammonia water in a tank 12 into the rotary kiln 1 is installed on the front surface of the rotary kiln 1 and is possible for the flame of the burner 2. By adjusting the spray position of the reducing agent such as urea water into the furnace so as not to touch it directly, the denitration reaction of nitrogen oxides in the exhaust gas in the rotary kiln 1 was made possible.

図１に示した並行流式のロータリーキルン型廃棄物焼却炉では、還元剤を噴霧するロータリーキルン１の前端温度は６５０〜７８０℃、後端温度は８００〜１０００℃近くであるため、本発明方法によれば炉内で十分に還元反応を促進し、排ガス中の窒素酸化物を低減させることができる。すなわち、排ガス中で尿素水から発生するアンモニアガスにより前記化学式１に示す還元反応がおこり、窒素酸化物が窒素ガスとなる。   In the parallel flow type rotary kiln type waste incinerator shown in FIG. 1, the front end temperature of the rotary kiln 1 sprayed with the reducing agent is 650 to 780 ° C., and the rear end temperature is close to 800 to 1000 ° C. Therefore, the reduction reaction can be sufficiently promoted in the furnace, and nitrogen oxides in the exhaust gas can be reduced. That is, the ammonia gas generated from urea water in the exhaust gas undergoes the reduction reaction shown in the chemical formula 1, and nitrogen oxides become nitrogen gas.

本発明に係る排ガスの脱硝方法では、還元剤の噴霧をスプレー散水（液滴）状態まで悪化させると良好な脱硝効果が得られなかったことから、効率的に排ガス中の窒素酸化物を脱硝するためにはミスト状に還元剤を噴霧する必要があることが判明した。前述の試験と同じ設備を使用し、下記の条件でミスト状に還元剤を噴霧した場合の実験結果を下記表２に示すが、本発明方法（ケース２〜４）では、良好な脱硝効果が確認され、還元剤噴霧設備への影響もなく、約３ヶ月間の長期安定操業が可能であった。   In the exhaust gas denitration method according to the present invention, if the spraying of the reducing agent is deteriorated to a spray water spray (droplet) state, a good denitration effect cannot be obtained. Therefore, nitrogen oxides in the exhaust gas are efficiently denitrated. In order to achieve this, it has been found necessary to spray the reducing agent in the form of a mist. Table 2 below shows the experimental results when the reducing agent is sprayed in the mist form under the following conditions using the same equipment as in the above test. In the method of the present invention (cases 2 to 4), a good denitration effect is obtained. It was confirmed that long-term stable operation for about 3 months was possible without affecting the reducing agent spraying equipment.

（試験条件）
１．先ず、尿素水の吹き込みをしない状態で、排ガス量、温度、ＮＯｘ濃度を測定（ケース１）。
２．次に、スプレー水量を３．０リットル／分、エアー圧力を３．０ｋｇ／ｍ2に調整した後、尿素水ストロークを１００％（ケース２）、５０％（ケース３）、２５％（ケース４）で吹き込み、排ガス量、温度、ＮＯｘ濃度を測定。 (Test conditions)
1. First, the amount of exhaust gas, temperature, and NOx concentration are measured without urea water blowing (Case 1).
2. Next, after adjusting the spray water amount to 3.0 liters / minute and the air pressure to 3.0 kg / m 2 , the urea water stroke is adjusted to 100% (case 2), 50% (case 3), 25% (case 4). ) And measure the amount of exhaust gas, temperature, and NOx concentration.

Figure 2005331204
Figure 2005331204

しかしながら、バーナ火炎に尿素水等の還元剤が接触すると、前述の化学式２，４に示したように、バーナ火炎により還元剤自体が燃焼して、還元剤としての効果を発揮させることが出来ず、この結果、排ガス中の窒素酸化物濃度が低減せず、かえって逆効果として尿素水に含まれる窒素分により窒素酸化物濃度の上昇を誘発する。そこで、本発明では、バーナ火炎との干渉を減じる位置に、ロータリーキルン１の前面から炉内に向けて還元剤を噴霧するのである。   However, when a reducing agent such as urea water comes into contact with the burner flame, as shown in the above chemical formulas 2 and 4, the reducing agent itself burns by the burner flame, and the effect as the reducing agent cannot be exhibited. As a result, the concentration of nitrogen oxides in the exhaust gas is not reduced. On the contrary, an increase in the concentration of nitrogen oxides is induced by the nitrogen content contained in the urea water as an adverse effect. Therefore, in the present invention, the reducing agent is sprayed from the front surface of the rotary kiln 1 into the furnace at a position where interference with the burner flame is reduced.

下記表３は、還元剤噴霧ノズル９の設置位置を、高さ方向には、バーナ２の設置位置より１．０ｍ上方（ケース１）、０．５ｍ上方（ケース２）、軸心と同じ（ケース３）、０．５ｍ下方（ケース４）の位置に、また、軸心方向には、バーナ２の先端より０．５ｍ炉外側（ケースＡ）、同じ（ケースＢ）、０．５ｍ炉内側（ケースＣ）の位置となるように変化させ、濃度が１４．７％の尿素水を、吹き込み水量が３リットル／分、エアー圧力が３．０ｋｇ／ｍ2で噴霧した場合の脱硝率を実験した結果を示したものである。 Table 3 below shows the installation position of the reducing agent spray nozzle 9 in the height direction, 1.0 m above the installation position of the burner 2 (case 1), 0.5 m above (case 2), and the same axis ( Case 3), 0.5 m below (case 4), and in the axial direction 0.5 m outside the furnace (case A), the same (case B), 0.5 m inside the furnace from the tip of the burner 2 (Case C) was changed to the position of the experiment, and the denitration rate when the concentration of 14.7% urea water was sprayed at an injection water volume of 3 liters / minute and an air pressure of 3.0 kg / m 2 was tested. The results are shown.

Figure 2005331204
Figure 2005331204

この表３の結果より、この実験条件の場合には、図４（ａ）にハッチングで示した範囲から還元剤を噴霧した場合には脱硝効果が得られ、望ましくは、バーナ２よりも上方から還元剤を噴霧した場合には良好な脱硝効果が得られることが判明した。   From the results in Table 3, in the case of this experimental condition, when the reducing agent is sprayed from the range shown by hatching in FIG. 4A, a denitration effect is obtained, and preferably from above the burner 2. It has been found that when the reducing agent is sprayed, a good denitration effect can be obtained.

上記の例は単なる一例であり、本発明は上記の例に限らず、各請求項に記載された技術的思想の範囲内で、適宜実施の形態を変更しても良いことは言うまでもない。   The above example is merely an example, and the present invention is not limited to the above example, and it goes without saying that the embodiment may be appropriately changed within the scope of the technical idea described in each claim.

以上の本発明は、廃棄物焼却炉に限らず、操業中における炉内温度が８００℃以上である箇所を含む回転炉であれば適用できる。   The present invention described above is not limited to a waste incinerator, and can be applied to any rotary furnace including a portion where the furnace temperature during operation is 800 ° C. or higher.

本発明方法を実施する設備のフローを示した図である。It is the figure which showed the flow of the equipment which enforces this invention method. ロータリーキルンの後端部から還元剤を噴霧した場合の問題点を説明する図である。It is a figure explaining the problem at the time of spraying a reducing agent from the rear-end part of a rotary kiln. 試験に使用した設備の、バーナと還元剤噴霧ノズルの相対位置関係を示した図で、（ａ）は正面から見た図、（ｂ）は側面から見た図である。It is the figure which showed the relative positional relationship of the burner and reducing agent spray nozzle of the equipment used for the test, (a) is the figure seen from the front, (b) is the figure seen from the side. 試験に使用した設備の、バーナと還元剤噴霧ノズルの相対位置関係を示した図で、（ａ）は正面から見た図、（ｂ）は側面から見た図である。It is the figure which showed the relative positional relationship of the burner and reducing agent spray nozzle of the equipment used for the test, (a) is the figure seen from the front, (b) is the figure seen from the side. 還元剤として尿素水やアンモニア水を噴霧した場合に、還元された窒素酸化物量及び燃焼により酸化されて生成された窒素酸化物量と、還元剤の反応率を示した図である。When spraying urea water or ammonia water as a reducing agent, it is a figure showing the amount of nitrogen oxides reduced, the amount of nitrogen oxides produced by oxidation by combustion, and the reaction rate of the reducing agent.

符号の説明Explanation of symbols

１ ロータリーキルン
２ バーナ
１１ 還元剤噴霧ノズル
1 Rotary kiln 2 Burner 11 Reducing agent spray nozzle

Claims (3)

ロータリーキルン型の回転炉における排ガス脱硝方法であって、
バーナ火炎との干渉を減じる位置に、
ロータリーキルンの前面から炉内に向けて還元剤を噴霧することを特徴とする回転炉における排ガス脱硝方法。 An exhaust gas denitration method in a rotary kiln type rotary furnace,
In a position that reduces interference with the burner flame,
An exhaust gas denitration method in a rotary furnace, wherein a reducing agent is sprayed from the front of the rotary kiln into the furnace. 前記ロータリーキルン型の回転炉は、操業中における炉内温度が８００℃以上である箇所を含む回転炉であることを特徴とする請求項１に記載の回転炉における排ガス脱硝方法。   2. The exhaust gas denitration method for a rotary furnace according to claim 1, wherein the rotary kiln type rotary furnace is a rotary furnace including a portion where the furnace temperature during operation is 800 ° C. or higher. 前記還元剤を噴霧する位置が、バーナ設置位置より炉体の上方であることを特徴とする請求項１又は２に記載の回転炉における排ガス脱硝方法。
The exhaust gas denitration method in a rotary furnace according to claim 1 or 2, wherein the position where the reducing agent is sprayed is above the furnace body from the burner installation position.
JP2004151913A 2004-05-21 2004-05-21 Exhaust gas denitration method in waste incinerator Pending JP2005331204A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013120146A (en) * 2011-12-08 2013-06-17 Ngk Insulators Ltd Method for treating radioactive cesium contaminated materials
JP2014070785A (en) * 2012-09-28 2014-04-21 Nippon Steel & Sumikin Chemical Co Ltd Combustion furnace including denitrification device
JP2019070488A (en) * 2017-10-10 2019-05-09 日鉄ケミカル＆マテリアル株式会社 Combustion furnace with denitration device
CN111514726A (en) * 2019-02-02 2020-08-11 广东万引科技发展有限公司 Novel composite biomass denitration agent for dry-process cement kiln, use method of denitration agent and denitration system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013120146A (en) * 2011-12-08 2013-06-17 Ngk Insulators Ltd Method for treating radioactive cesium contaminated materials
JP2014070785A (en) * 2012-09-28 2014-04-21 Nippon Steel & Sumikin Chemical Co Ltd Combustion furnace including denitrification device
JP2019070488A (en) * 2017-10-10 2019-05-09 日鉄ケミカル＆マテリアル株式会社 Combustion furnace with denitration device
JP7320917B2 (en) 2017-10-10 2023-08-04 日鉄ケミカル＆マテリアル株式会社 Combustion furnace with denitration equipment
CN111514726A (en) * 2019-02-02 2020-08-11 广东万引科技发展有限公司 Novel composite biomass denitration agent for dry-process cement kiln, use method of denitration agent and denitration system
CN111514726B (en) * 2019-02-02 2024-01-26 广东万引科技发展有限公司 Novel composite biomass denitration agent for dry-method cement kiln, application method of novel composite biomass denitration agent and denitration system

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