JP2004298814A

JP2004298814A - Fluid mixing apparatus

Info

Publication number: JP2004298814A
Application number: JP2003097410A
Authority: JP
Inventors: Hiroshi Ishizaka; 浩石坂; Masaaki Ishioka; 正明石岡
Original assignee: Babcock Hitachi KK
Current assignee: Mitsubishi Power Ltd
Priority date: 2003-03-31
Filing date: 2003-03-31
Publication date: 2004-10-28
Anticipated expiration: 2023-03-31
Also published as: JP4086150B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid mixing apparatus having a simple and compact structure, permitting uniform dispersion of a fluid, such as a gas or a liquid and requiring no work for e.g. regulation of the flow rate. <P>SOLUTION: In a duct 1 of a rectangular cross section serving as a passage for a gas, there is provided a nozzle 2 for injection of a different gas or liquid. Mixing plates 4, 4 are protruded respectively from a pair of mutually opposing inside wall surfaces of the duct in the vicinity of the nozzle 2, and mixing plates 5 are protruded respectively from a pair of mutually opposing inside wall surfaces of the duct at positions downstream to the plates 4 on the side of the duct without the plates. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【産業上の利用分野】
本発明は、ボイラ、ゴミ焼却炉、ディーゼルやマイクロガスタービンなどの燃焼装置から排出される排ガス中の窒素酸化物（ＮＯｘ）を除去する脱硝装置におけるアンモニア供給装置などの流体混合装置に係わり、特に、簡易かつコンパクトな構造でアンモニアなどの気体供給源となるガスや液体を均一に分散できる流体混合装置に関するものである。また、本発明は、大量のガスに別種の微量ガスを均一に混ぜるための単なるガス混合器としても用いることができるものである。
【０００２】
【従来の技術】
従来技術の流体分散供給装置および混合器の公知例を図８、図９ならびに図１０に示す。図８は一般的な液体分散供給装置が組込まれた主流ガスが流れるダクトのガス流れ方向に沿った断面の鳥瞰図であり、図９、図１０は該液体分散供給装置の一部分の拡大図である。
【０００３】
本流体分散供給装置は、主流ガスが流れるダクト１と該ダクト１内に配置された分散ノズル２から構成され、ダクト１内に微量のガスまたは液体などの流体を分散ノズル２を通じて分散しようとするものである。このような流体分散供給装置は、燃焼排ガス中の窒素酸化物を処理する脱硝装置におけるアンモニア源の供給装置として利用されることが多い。その場合、アンモニア源としてアンモニア水が用いられることが多く、分散ノズル２からはアンモニア水がスプレされ、蒸発した後、アンモニアガスとして拡散することになる。
【０００４】
しかし、図８のように１個の分散ノズル２でアンモニア水をスプレしようとすると、その分散性が乏しく、排ガス中にアンモニア濃度分布が生じることになり、一般に分散ノズル２の下流側に設置される図示していない脱硝触媒での性能低下や処理ガスへのアンモニアリークなどの問題が発生する。分散ノズル２から図示していない脱硝触媒までの距離を長くすればアンモニア濃度分布をある程度均一化することはできるが、脱硝システム全体が大きなものとなってしまう。
【０００５】
この対策として、図９に示すように分散ノズル２を複数化する方法が採用される場合が多いが（例えば、特許文献１参照）、この場合、ダクト１内におけるガス偏流に合わせて各分散ノズル２からスプレされるアンモニア水量を調整する必要があり、また、ダクト１のサイズが小さい場合、物理的に分散ノズル２を複数配置できないこともある。
【０００６】
また、図１０に示すような四角錐の各平面に開口を設けた立体構造から成る混合器３を分散ノズル２の近傍あるいは下流側に設置することでもアンモニアの分散、混合を促進することができるが（例えば、特許文献２参照）立体構造の混合器３は一般に圧力損失が大きく、製作コストも高い。さらに、分散ノズル２からスプレする流体がガスの場合には、それほど問題にはならないが、アンモニア水や尿素水などの液体をスプレする場合には、それらの液体が蒸発完了する位置よりも下流側に混合器３を配置する必要があり、その混合器３から図示していない脱硝触媒の間にある程度の混合距離が必要であるため、アンモニアの均一化に要するダクトが長くなり、脱硝システム全体のコンパクト化を図ることが難しくなる。
【０００７】
【特許文献１】
特開平０８−１０３６２８号公報
【０００８】
【特許文献２】
特開平０９−０７５６７３号公報
【０００９】
【発明が解決しようとする課題】
上記従来技術は、主流ガスに微量のガス・液体などの流体を均一に分散供給する点について十分配慮されておらず、排ガス処理システム全体のコンパクト性が損なわれるとともに、システムが複雑化し、また流体圧力損失が増加し、さらに試運転調整作業が複雑化するなどの問題があった。
【００１０】
本発明の課題は、上記問題点を解消し、簡易かつコンパクトな構造でアンモニアなどのガスや液体などの流体を均一に分散でき、しかも流量調整などの作業が不要な流体混合装置を提供することにある。
【００１１】
【課題を解決するための手段】
上記本発明の課題は次の解決手段により解決される。
請求項１記載の発明は、ガスが流れる流路となる断面角型のダクト内に、前記ガスとは別種のガス及び／又は液体を注入するノズルを備えた流体混合装置において、ノズル近傍における一組の相対向するダクト内壁面に、ダクト内のガス流路内の一部を塞ぐようにそれぞれ混合板を内壁面から突出させ、さらに、前記混合板を設置していない側の一組の相対向するダクト内壁面の上記混合板よりも下流側の位置にも、ガス流路の一部を塞ぐように混合板を内壁面から突出させた流体混合装置である。
【００１２】
請求項２記載の発明は、ダクトの上流側と下流側の二段に設置する混合板をガス流れに直交する同一平面に投影した場合の開口率を２０％〜４５％の範囲になるように混合板の大きさを設定した請求項１に記載の流体混合装置である。
【００１３】
請求項３記載の発明は、ダクトのガス流れに直交する断面積Ａに対するノズルから上流側混合板までの距離ｈの割合ｈ／Ａを−０．４ｍ／ｍ^２（ノズルの上流側）〜０．６ｍ／ｍ^２（ノズルの下流側）の範囲に設置した請求項１ないし２に記載の流体混合装置である。
【００１４】
請求項４記載の発明は、ダクト断面積Ａに対する二段に設置する混合板同士の間隔ΔＨの割合ΔＨ／Ａを０．５ｍ／ｍ^２以下にした請求項１ないし３のいずれかに記載の流体混合装置である。
請求項５記載の発明は、断面角型ダクトのガス流れに直交する断面形状が長方形の場合に、一組の相対するダクト内面の短辺側に上流側混合板を設置し、一組の相対するダクト内面の長辺側に下流側混合板を設置した請求項１ないし４のいずれかに記載の流体混合装置である。
請求項６記載の発明は、ダクト内壁に設置する混合板を壁側からガス流れ上流側に向けて傾斜配置させた請求項１ないし５のいずれかに記載の流体混合装置である。
【００１５】
【作用】
請求項１記載の発明によれば、アンモニア水などのノズルから噴出される流体が届き難いダクト内壁面近傍で流体が吹抜けるのを阻止し、ノズル近傍に縮流を形成することによって異種流体の分散性を高め、さらに混合器の下流側に渦を積極的に発生させることにより、異種流体の混合性を向上させることができる。
【００１６】
また、請求項１記載の発明は、基本的に縮流を形成させるためにダクト内壁面の全周に混合板を設置する構造であり、高い混合性能を得るためには混合板の設置面における開口率を下げる必要がある。ただし、開口率を下げると混合板部分での流体の圧力損失を増大させることになるが、請求項１記載の発明は、上流側と下流側の二段に分け、それぞれの段において混合板の設置方向を変えているため、それぞれの段における開口率を上げることができ、流体の圧力損失を小さくすることが可能となる。
【００１７】
また、請求項１記載の発明によれば、基本的にノズルの下流側に混合板が配置されているが、混合板はすべてダクト内壁側に取付けられているため、ノズルからスプレされた、例えばアンモニア水液滴が直接混合板に衝突することもなく、蒸発不良などに起因するトラブルが生じる可能性がない。
【００１８】
請求項２記載の発明によれば、混合板をガス流れに直交する同一平面に投影した場合の開口率を２０％〜４５％の範囲になるように混合板の大きさを設定することで、異種の流体同士の高い混合率を大きな圧力損失がない状態で達成できる。
【００１９】
請求項３記載の発明によれば、ダクトのガス流れに直交する断面積Ａに対するノズルから上流側混合板までの距離ｈの割合ｈ／Ａを−０．４ｍ／ｍ^２（ノズルの上流側）〜０．６ｍ／ｍ^２（ノズルの下流側）の範囲に設置したことにより、異種の流体の混合性能を高めることができる。
【００２０】
請求項４記載の発明によれば、ダクト断面積Ａに対する二段に設置する混合板同士の間隔ΔＨの割合ΔＨ／Ａを０．５ｍ／ｍ^２以下にしたことにより、異種の流体の混合性能を高めることができる。
【００２１】
請求項５記載の発明によれば、断面角型ダクトのガス流れに直交する断面形状が長方形の場合に、一組の相対するダクト内面の短辺側に上流側混合板を設置し、一組の相対するダクト内面の長辺側に下流側混合板を設置したことにより、長辺側に上流側混合板を設置し、短辺側に下流側混合板を設置した場合に比較して、ノズル近傍において該ノズルから噴出される流体がダクト内壁面に届き易くなる。
【００２２】
請求項６記載の発明によれば、ダクト内壁に設置する混合板を壁側からガス流れ上流側に向けて傾斜配置させたことにより、混合板の上にダストが堆積することがなくなる。
【００２３】
【発明の実施の形態】
以下、本発明の実施例について図面を用いて説明する。
【００２４】
【実施例】
図１は本発明による一実施例であり、流体混合装置が組込まれた主流ガス流れＧが流れるダクト１のガス流れ方向に沿った断面の鳥瞰図を示したものである。図２は図１の実施例のダクトのガス流れ方向の断面図（図２（ａ））とガス流れＧの下流側から見た図２（ａ）のＡ−Ａ線矢視図（図２（ｂ））とＢ−Ｂ線矢視図（図２（ｃ））を示したものである。
【００２５】
矩形断面を有するダクト１のガス流れＧの上流側の混合板４が対向する壁面に対して垂直方向に向けて、該壁面から突出するように壁面全域に設けられている。また、上流側混合板４の下流側の前記混合板４が設けられていない対向する壁面に下流側混合板５が同じく壁面に垂直方向に向けて、該壁面から突出するように壁面全域に設けられている。分散ノズル２は一対の上流側混合板４と同一ダクト横断面域のダクト中心部に噴出口を持つように上流側混合板４のなす平面に沿う方向に管体が設けられている。
【００２６】
図３はダクト１のガス流れ方向に二段に設置する混合板４、５を同一平面に投影した場合のダクト１の開口率と、混合板４、５の下流側におけるアンモニア濃度変動率の関係及び混合板圧力損失（ｍｍＨ_２Ｏ）の関係を示したものである。図４はダクト断面積Ａに対する分散ノズル２から上流側混合板４までの距離ｈの割合ｈ／Ａと、アンモニア濃度変動率および混合板圧力損失の関係を示したものである。図５はダクト断面積Ａに対する二段に設置する混合板４、５同士の間隔ΔＨの割合ΔＨ／Ａと、アンモニア濃度変動率および混合板圧力損失の関係を示したものである。
【００２７】
なお、本発明のような流体混合装置は、燃焼排ガス中の窒素酸化物を処理する脱硝装置におけるアンモニア源の供給装置として利用されることが多いため、分散ノズル２からは流体としてアンモニア水がスプレされ、蒸発した後アンモニアガスとして拡散するものとして、以下本発明の実施例を説明する。
【００２８】
図１に示す実施例は、分散ノズル２近傍における一組の相対向するダクト１内壁の両面に、ガス流路の一部を塞ぐように上流側混合板４を壁から突出させ、さらに、上流側混合板４を設置していない側の一組の相対するダクト１内壁の両面の上流側混合板４よりも下流側の位置に、ガス流路の一部を塞ぐように下流側混合板５を壁から突出させた点で従来技術と異なる。
【００２９】
まず、本発明によるダクト１に配置される上流側混合板４および下流側混合板５は、アンモニアが届き難いダクト１の内壁近傍でのガスの吹抜けを阻止し、分散ノズル２近傍に縮流を形成することによってアンモニア水の分散性を高め、さらに上流側混合板４ならびに下流側混合板５の下流側に渦を積極的に発生させることにより蒸発後のアンモニアガスの混合性を向上させることができる。
【００３０】
また、上流側混合板４および下流側混合板５は全てダクト１の内壁側に取付けられているため、分散ノズル２からスプレされたアンモニア水液滴が直接混合板４、５に衝突することもなく、蒸発不良などに起因するトラブルが生じる可能性がない。
【００３１】
また、上流側混合板４および下流側混合板５は、基本的に縮流を形成させるためにダクト１の内壁全周に混合板を設置する構造であり、混合板設置面におけるダクト開口率を下げることで高い混合性能を得ることが可能である。しかし、前記開口率を下げすぎると混合板４、５の圧力損失を増大させることになる。図３にダクト１のガス流れ方向に二段に設置する混合板４、５を同一平面に投影した場合のダクト開口率と、混合板４、５の下流側におけるアンモニア濃度変動率の関係を示す。アンモニア濃度変動率とは、アンモニア平均濃度に対するアンモニア濃度の標準偏差の割合を表した値である。ダクト開口率を下げるとアンモニア濃度変動率を低減できるが、混合板の圧力損失が増大することが分かる。特にダクト開口率２０％以下での増加が激しい。一般に分散ノズル２の下流側に設置される図示していない脱硝触媒設置部でのガスの脱硝性能に影響を及ぼさないアンモニア濃度変動率の許容値は３０％以下であるとされているため、アンモニア濃度変動率と混合板４、５による圧力損失を考慮したダクト開口率の適正範囲は、２０％〜４５％である。
【００３２】
また、本発明における実施例においては、上流側混合板４と下流側混合板５の設置位置によってもアンモニアの混合性は影響を受ける。図４に上流側混合板４と下流側混合板５の間隔を固定した場合のダクト断面積Ａに対する分散ノズル２から上流側混合板４までの距離ｈの割合ｈ／Ａと、アンモニア濃度変動率および混合板圧力損失の関係を示す。ｈ／Ａの値は混合板圧力損失に対してはほとんど影響していないが、アンモニア濃度変動率に対しては０近傍が望ましいことが分かる。許容変動率を３０％以下とすれば、ｈ／Ａの適正範囲は−０．４〜０．６ｍ／ｍ^２となる。
【００３３】
図５にはダクト断面積Ａに対する上下段の混合板同士の間隔ΔＨの割合ΔＨ／Ａと、アンモニア濃度変動率および混合板圧力損失の関係を示す。本条件では、いずれのΔＨ／Ａにおいてもアンモニア濃度変動率は３０％以下であるが、ΔＨ／Ａ以外の条件が変われば３０％を超える場合も出てくると考えられるため、ΔＨ／Ａの適正範囲は、アンモニア濃度変動率の低下が始まる０．５ｍ／ｍ^２以下である。また、混合板圧力損失に対する影響は小さいため、圧力損失の面からの制約条件はない。
【００３４】
なお、ΔＨ／Ａ＝０は上流側混合板４と下流側混合板５を一体化した場合の結果を示すことになるが、アンモニア濃度変動率は、ほぼ同程度であるのに対して、混合板圧力損失が高くなっていることが分かる。このことからも混合板４、５を上流側と下流側に二段に分けた場合により効果的であることが分かる。
【００３５】
なお、図１に示した実施例では長方形断面を有するダクト１の短辺側に上流側混合板４を、長辺側に下流側混合板５を設置しているが、分散ノズル２近傍においてアンモニアが届き難く、ガスの吹抜けが発生しやすいダクト１の短辺側に上流側混合板４を設置することで、本実施例の効果を最大限に得ることができる。
【００３６】
【他の実施例】
図６に示す他の実施例は、混合板４、５をダクト１内壁側から斜め下に伸びるように傾斜させた点で図１に示した実施例と異なる。排ガス中にダストを含む場合に有効な手段であり、上流側混合板４および下流側混合板５の上にダストが堆積することがない。堆積ダストの落下による分散ノズル２の閉塞などのトラブルを防止することができる。
【００３７】
図７に示す実施例は、混合板４、５の先端部とダクト壁面の間に水平板を取付け、ガス流れのよどみ部をなくした点で図６に示した実施例と異なる。ガス流れに不安定なよどみ部が存在することで混合板４、５の振動が生じやすい場合に有効な手段である。
【００３８】
【発明の効果】
請求項１記載の発明によれば、簡易かつコンパクトな構造で圧力損失を増加させることなく、主流ガスに微量のガスあるは液体などの流体を均一に分散供給できる流体混合装置を提供することが可能となる。
請求項２記載の発明によれば、請求項１記載の発明の効果に加えて、異種の流体同士の高い混合率を大きな圧力損失がない状態で達成できる。
【００３９】
請求項３記載の発明によれば、請求項１又は２記載の発明の効果に加えて、さらに異種の流体の混合性能を高めることができる。
【００４０】
請求項４記載の発明によれば、請求項１ないし３のいずれかに記載の発明の効果に加えて、さらに異種の流体の混合性能を高めることができる。
【００４１】
請求項５記載の発明によれば、請求項１ないし４のいずれかに記載の発明の効果に加えて、ノズル近傍において該ノズルから噴出される流体がダクト内壁面に届き易くなり、さらに異種の流体の混合性能を高めることができる。
請求項６記載の発明によれば、請求項１ないし５のいずれかに記載の発明の効果に加えて、混合板の上にダストが堆積することがなくなる。堆積ダストの落下による分散ノズル２の閉塞などのトラブルを防止することができる。
【図面の簡単な説明】
【図１】本発明の一実施例の流体混合装置が組込まれた主流ガスが流れるダクトのガス流れ方向に沿った断面の鳥瞰図を示したものである。
【図２】図１のダクトのガス流れ方向の断面図（図２（ａ））とガス流れＧの下流側から見た図２（ａ）のＡ−Ａ線矢視図（図２（ｂ））とＢ−Ｂ線矢視図（図２（ｃ））を示したものである。
【図３】図１の実施例において二段に設置する混合板を同一平面に投影した場合のダクト開口率と、混合板の下流側におけるアンモニア濃度変動率及び混合板圧力損失の関係を示したものである。
【図４】図１の実施例においてダクト断面積Ａに対する分散ノズルから上流側混合板までの距離ｈの割合ｈ／Ａと、アンモニア濃度変動率および混合板圧力損失の関係を示したものである。
【図５】図１の実施例においてダクト断面積Ａに対する二段に設置する混合板同士の間隔ΔＨの割合ΔＨ／Ａと、アンモニア濃度変動率および混合板圧力損失の関係を示したものである。
【図６】本発明の他の実施例においてダクトの対向壁面にそれぞれ設置する一対の上流側混合板と下流側混合板をダクト内壁側から上流側に傾斜させた場合のガス流れＧの方向に沿った断面を見た図（図６（ａ））と図６（ａ）のＡ−Ａ線矢視図（図６（ｂ））を示したものである。
【図７】本発明の他の実施例におけるダクトのガス流れ方向の断面を見た図（図７（ａ））と図７（ａ）のＡ−Ａ線矢視図（図７（ｂ））である。
【図８】従来技術の流体混合装置が組込まれた主流ガスが流れるダクトのガス流れ方向に沿った断面の鳥瞰図を示したものである。
【図９】図８の分散ノズルを４個に増設した従来技術を示したものである。
【図１０】図８もしくは図９の分散ノズルの下流側に一般的な立体構造から成る混合器を設けた従来技術を示したものである。
【符号の説明】
１ダクト２分散ノズル
３混合器４上流側の混合板
５下流側混合板
Ｇガス流れ[0001]
[Industrial applications]
The present invention relates to a fluid mixing device such as an ammonia supply device in a denitration device for removing nitrogen oxides (NOx) in exhaust gas discharged from a combustion device such as a boiler, a waste incinerator, a diesel or a micro gas turbine, and in particular, More specifically, the present invention relates to a fluid mixing apparatus that can uniformly disperse a gas or liquid serving as a gas supply source such as ammonia with a simple and compact structure. Further, the present invention can be used as a simple gas mixer for uniformly mixing a large amount of gas with another kind of trace gas.
[0002]
[Prior art]
FIGS. 8, 9 and 10 show known examples of a fluid dispersion supply device and a mixer of the prior art. FIG. 8 is a bird's-eye view of a cross section along a gas flow direction of a duct in which a mainstream gas flows in which a general liquid dispersion supply device is incorporated, and FIGS. 9 and 10 are enlarged views of a part of the liquid dispersion supply device. .
[0003]
The fluid dispersion and supply device includes a duct 1 through which a mainstream gas flows, and a dispersion nozzle 2 disposed in the duct 1, and attempts to disperse a small amount of fluid such as gas or liquid through the dispersion nozzle 2 in the duct 1. Things. Such a fluid dispersion supply device is often used as a supply device of an ammonia source in a denitration device for treating nitrogen oxides in combustion exhaust gas. In that case, ammonia water is often used as an ammonia source, and the ammonia water is sprayed from the dispersing nozzle 2, evaporates, and then diffuses as ammonia gas.
[0004]
However, as shown in FIG. 8, when spraying ammonia water with one dispersing nozzle 2, the dispersibility is poor and an ammonia concentration distribution is generated in the exhaust gas. However, problems such as deterioration in performance of a denitration catalyst (not shown) and leakage of ammonia to the processing gas occur. If the distance from the dispersion nozzle 2 to the denitration catalyst (not shown) is increased, the ammonia concentration distribution can be made uniform to some extent, but the entire denitration system becomes large.
[0005]
As a countermeasure, a method of using a plurality of dispersion nozzles 2 is often adopted as shown in FIG. 9 (for example, see Patent Document 1). In this case, each dispersion nozzle 2 is adjusted according to the gas drift in the duct 1. It is necessary to adjust the amount of ammonia water sprayed from step 2, and when the size of the duct 1 is small, a plurality of dispersion nozzles 2 may not be physically arranged.
[0006]
Also, the dispersing and mixing of ammonia can be promoted by installing a mixer 3 having a three-dimensional structure having openings in each plane of a quadrangular pyramid as shown in FIG. 10 near or downstream of the dispersing nozzle 2. However, the mixer 3 having a three-dimensional structure generally has a large pressure loss and a high manufacturing cost. Further, when the fluid sprayed from the dispersion nozzle 2 is a gas, this is not so problematic. However, when spraying liquids such as ammonia water and urea water, the liquid downstream of the position where the evaporation of the liquid is completed It is necessary to arrange the mixer 3 in the mixer, and a certain mixing distance is required between the mixer 3 and a denitration catalyst (not shown). It becomes difficult to achieve compactness.
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 08-103628
[Patent Document 2]
Japanese Patent Application Laid-Open No. 09-075673
[Problems to be solved by the invention]
The above-mentioned prior art does not sufficiently take into consideration the point of uniformly distributing and supplying a small amount of fluid such as gas or liquid to the mainstream gas, which impairs the compactness of the entire exhaust gas treatment system, complicates the system, There have been problems such as an increase in pressure loss, and further complicating the trial operation adjustment work.
[0010]
It is an object of the present invention to provide a fluid mixing device that solves the above-mentioned problems, and can uniformly disperse a fluid such as a gas such as ammonia or a liquid with a simple and compact structure, and does not require an operation such as a flow rate adjustment. It is in.
[0011]
[Means for Solving the Problems]
The object of the present invention is solved by the following means.
According to a first aspect of the present invention, there is provided a fluid mixing device including a nozzle for injecting a gas and / or a liquid different from the gas in a duct having a rectangular cross section serving as a flow path of the gas. A pair of opposing inner walls of the duct, each of which protrudes a mixing plate from the inner wall so as to close a part of the gas flow path in the duct, and further, a pair of relative sides on which the mixing plate is not installed A fluid mixing device in which a mixing plate is protruded from an inner wall surface at a position downstream of the mixing plate on a facing inner wall surface of the duct so as to block a part of the gas flow path.
[0012]
According to the second aspect of the present invention, the opening ratio when the mixing plates installed at the two stages on the upstream side and the downstream side of the duct are projected on the same plane orthogonal to the gas flow is in the range of 20% to 45%. The fluid mixing device according to claim 1, wherein a size of the mixing plate is set.
[0013]
According to a third aspect of the present invention, the ratio h / A of the distance h from the nozzle to the upstream mixing plate with respect to the cross-sectional area A orthogonal to the gas flow in the duct is -0.4 m / m ² (upstream of the nozzle) to 0. The fluid mixing device according to claim 1, wherein the fluid mixing device is installed in a range of 0.6 m / m ² (downstream of the nozzle).
[0014]
According to a fourth aspect of the present invention, the ratio ΔH / A of the interval ΔH between the mixing plates installed in two stages with respect to the duct cross-sectional area A is set to 0.5 m / m ² or less. It is a fluid mixing device.
According to a fifth aspect of the present invention, when the cross-sectional shape orthogonal to the gas flow of the rectangular cross-section duct is rectangular, an upstream-side mixing plate is installed on the short side of a pair of opposed inner surfaces of the duct, and The fluid mixing device according to any one of claims 1 to 4, wherein a downstream mixing plate is provided on a long side of the inner surface of the duct.
The invention according to claim 6 is the fluid mixing device according to any one of claims 1 to 5, wherein the mixing plate installed on the inner wall of the duct is arranged to be inclined from the wall side toward the upstream side of the gas flow.
[0015]
[Action]
According to the first aspect of the present invention, it is possible to prevent a fluid such as ammonia water from ejecting from a nozzle near the inner wall surface of the duct, which is difficult to reach, to prevent the fluid from flowing through, and to form a condensed flow near the nozzle to thereby prevent the heterogeneous fluid from flowing. By increasing the dispersibility and positively generating a vortex downstream of the mixer, the mixing property of different kinds of fluids can be improved.
[0016]
The invention according to claim 1 has a structure in which a mixing plate is installed on the entire circumference of the inner wall surface of the duct in order to form a contraction flow. It is necessary to lower the aperture ratio. However, lowering the aperture ratio increases the pressure loss of the fluid at the mixing plate portion. However, the invention according to claim 1 is divided into two stages, an upstream side and a downstream side, and the mixing plate is disposed in each stage. Since the installation direction is changed, the aperture ratio in each stage can be increased, and the pressure loss of the fluid can be reduced.
[0017]
According to the first aspect of the present invention, the mixing plate is basically disposed downstream of the nozzle. However, since all the mixing plates are attached to the inner wall of the duct, the mixing plate is sprayed from the nozzle. Ammonia water droplets do not directly collide with the mixing plate, and there is no possibility that troubles due to poor evaporation or the like will occur.
[0018]
According to the second aspect of the invention, the size of the mixing plate is set such that the aperture ratio when the mixing plate is projected on the same plane orthogonal to the gas flow is in the range of 20% to 45%. A high mixing ratio between different kinds of fluids can be achieved without a large pressure loss.
[0019]
According to the third aspect of the present invention, the ratio h / A of the distance h from the nozzle to the upstream mixing plate with respect to the cross-sectional area A orthogonal to the gas flow in the duct is -0.4 m / m ² (upstream of the nozzle). By installing in the range of 0.6 m / m ² (downstream of the nozzle), the mixing performance of different kinds of fluids can be improved.
[0020]
According to the fourth aspect of the present invention, the ratio ΔH / A of the interval ΔH between the mixing plates installed in two stages with respect to the duct cross-sectional area A is set to 0.5 m / m ² or less, so that the mixing performance of different kinds of fluids is improved. Can be increased.
[0021]
According to the fifth aspect of the present invention, when the cross-sectional shape orthogonal to the gas flow of the rectangular cross-section duct is rectangular, the upstream-side mixing plate is installed on the short side of the pair of opposed inner surfaces of the duct. By installing the downstream mixing plate on the long side of the inner surface of the opposing duct, the upstream mixing plate is installed on the long side and the downstream mixing plate is installed on the short side. In the vicinity, the fluid ejected from the nozzle easily reaches the inner wall surface of the duct.
[0022]
According to the sixth aspect of the present invention, since the mixing plate installed on the inner wall of the duct is inclined from the wall side toward the upstream side of the gas flow, dust does not accumulate on the mixing plate.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
【Example】
FIG. 1 is an embodiment according to the present invention, and shows a bird's-eye view of a cross section along a gas flow direction of a duct 1 in which a mainstream gas flow G in which a fluid mixing device is incorporated flows. FIG. 2 is a cross-sectional view of the duct of the embodiment of FIG. 1 in the gas flow direction (FIG. 2A) and a view taken along the line AA of FIG. 2A viewed from the downstream side of the gas flow G (FIG. (B)) and a view taken along the line BB (FIG. 2 (c)).
[0025]
The mixing plate 4 on the upstream side of the gas flow G of the duct 1 having a rectangular cross section is provided on the entire wall surface so as to protrude from the wall surface in a direction perpendicular to the wall surface facing the gas flow G. Further, a downstream mixing plate 5 is provided on the opposite wall surface on which the mixing plate 4 is not provided downstream of the upstream mixing plate 4 so as to extend in a direction perpendicular to the wall surface and also from the wall surface so as to protrude from the wall surface. Have been. The dispersion nozzle 2 is provided with a pipe in a direction along a plane formed by the upstream mixing plate 4 so as to have an ejection port at the center of the duct in the same duct cross-sectional area as the pair of upstream mixing plates 4.
[0026]
FIG. 3 shows the relationship between the opening ratio of the duct 1 when the mixing plates 4 and 5 installed in two stages in the gas flow direction of the duct 1 are projected on the same plane and the ammonia concentration fluctuation rate on the downstream side of the mixing plates 4 and 5. And the pressure loss of the mixing plate (mmH ₂ O). FIG. 4 shows the relationship between the ratio h / A of the distance h from the dispersion nozzle 2 to the upstream mixing plate 4 with respect to the duct cross-sectional area A, and the ammonia concentration fluctuation rate and the mixing plate pressure loss. FIG. 5 shows the relationship between the ratio ΔH / A of the interval ΔH between the mixing plates 4 and 5 installed in two stages with respect to the duct cross-sectional area A, the ammonia concentration variation rate, and the pressure loss of the mixing plate.
[0027]
In addition, since the fluid mixing device as in the present invention is often used as an ammonia source supply device in a denitration device for treating nitrogen oxides in combustion exhaust gas, ammonia water is sprayed from the dispersion nozzle 2 as a fluid. An example of the present invention will be described below assuming that the gas is evaporated and then diffused as ammonia gas.
[0028]
In the embodiment shown in FIG. 1, an upstream mixing plate 4 is protruded from both sides of a pair of opposed ducts 1 near the dispersion nozzle 2 so as to block a part of a gas flow path. The downstream mixing plate 5 is provided at a position downstream of the upstream mixing plate 4 on both inner surfaces of the pair of opposed ducts 1 on which the side mixing plate 4 is not installed so as to block a part of the gas flow path. Is different from the prior art in that it protrudes from the wall.
[0029]
First, the upstream-side mixing plate 4 and the downstream-side mixing plate 5 arranged in the duct 1 according to the present invention prevent gas from flowing through near the inner wall of the duct 1 where ammonia does not easily reach, and reduce the flow near the dispersion nozzle 2. It is possible to improve the dispersibility of the ammonia water by forming, and to improve the mixing property of the ammonia gas after evaporation by positively generating a vortex downstream of the upstream mixing plate 4 and the downstream mixing plate 5. it can.
[0030]
Further, since the upstream mixing plate 4 and the downstream mixing plate 5 are all mounted on the inner wall side of the duct 1, the ammonia water droplets sprayed from the dispersion nozzle 2 may directly collide with the mixing plates 4, 5. And there is no possibility that troubles due to poor evaporation or the like will occur.
[0031]
The upstream side mixing plate 4 and the downstream side mixing plate 5 have a structure in which a mixing plate is basically provided around the entire inner wall of the duct 1 in order to form a contraction flow. By lowering the value, it is possible to obtain high mixing performance. However, if the opening ratio is too low, the pressure loss of the mixing plates 4 and 5 will increase. FIG. 3 shows the relationship between the duct opening ratio when the mixing plates 4 and 5 installed in two stages in the gas flow direction of the duct 1 are projected on the same plane, and the ammonia concentration fluctuation rate on the downstream side of the mixing plates 4 and 5. . The ammonia concentration change rate is a value representing the ratio of the standard deviation of the ammonia concentration to the average ammonia concentration. It can be seen that reducing the duct opening ratio can reduce the ammonia concentration fluctuation rate, but increases the pressure loss of the mixing plate. In particular, the increase is sharp at a duct opening ratio of 20% or less. Generally, the allowable value of the ammonia concentration fluctuation rate which does not affect the denitration performance of the gas in the denitration catalyst installation section (not shown) installed downstream of the dispersion nozzle 2 is assumed to be 30% or less. An appropriate range of the duct opening ratio in consideration of the concentration fluctuation rate and the pressure loss due to the mixing plates 4 and 5 is 20% to 45%.
[0032]
In the embodiment of the present invention, the installation position of the upstream mixing plate 4 and the downstream mixing plate 5 also affects the mixing property of ammonia. FIG. 4 shows the ratio h / A of the distance h from the dispersion nozzle 2 to the upstream mixing plate 4 with respect to the cross-sectional area A of the duct when the distance between the upstream mixing plate 4 and the downstream mixing plate 5 is fixed, and the ammonia concentration fluctuation rate. And the relationship between the pressure loss of the mixing plate and the mixing plate. It can be seen that the value of h / A has little effect on the pressure loss of the mixing plate, but it is desirable that the value of h / A is close to 0 for the ammonia concentration fluctuation rate. If the allowable variation rate is 30% or less, the appropriate range of h / A is −0.4 to 0.6 m / m ² .
[0033]
FIG. 5 shows the relationship between the ratio ΔH / A of the interval ΔH between the upper and lower mixing plates to the duct cross-sectional area A, the ammonia concentration variation rate, and the mixing plate pressure loss. Under these conditions, the ammonia concentration fluctuation rate is 30% or less for any ΔH / A. However, if the conditions other than ΔH / A change, the ammonia concentration fluctuation rate may exceed 30%. An appropriate range is 0.5 m / m ² or less at which the ammonia concentration variation rate starts to decrease. In addition, since the influence on the pressure loss of the mixing plate is small, there are no restrictions on the pressure loss.
[0034]
Note that ΔH / A = 0 indicates the result when the upstream mixing plate 4 and the downstream mixing plate 5 are integrated, but the ammonia concentration fluctuation rate is almost the same, It can be seen that the plate pressure loss is high. From this, it can be seen that it is more effective when the mixing plates 4 and 5 are divided into two stages on the upstream side and the downstream side.
[0035]
In the embodiment shown in FIG. 1, the upstream side mixing plate 4 is installed on the short side of the duct 1 having a rectangular cross section, and the downstream side mixing plate 5 is installed on the long side. By installing the upstream mixing plate 4 on the short side of the duct 1 where the gas does not easily reach and gas blow-through is likely to occur, the effect of this embodiment can be obtained to the maximum.
[0036]
[Other embodiments]
The other embodiment shown in FIG. 6 differs from the embodiment shown in FIG. 1 in that the mixing plates 4, 5 are inclined so as to extend obliquely downward from the inner wall side of the duct 1. This is an effective means when dust is contained in the exhaust gas, and dust does not accumulate on the upstream mixing plate 4 and the downstream mixing plate 5. It is possible to prevent troubles such as clogging of the dispersion nozzle 2 due to falling of accumulated dust.
[0037]
The embodiment shown in FIG. 7 is different from the embodiment shown in FIG. 6 in that a horizontal plate is attached between the distal end portions of the mixing plates 4 and 5 and the duct wall surface, and a gas flow stagnation portion is eliminated. This is an effective means when the vibration of the mixing plates 4 and 5 is likely to occur due to the presence of an unstable stagnation portion in the gas flow.
[0038]
【The invention's effect】
According to the first aspect of the present invention, it is possible to provide a fluid mixing device capable of uniformly distributing and supplying a small amount of gas or a liquid such as a liquid to a mainstream gas without increasing pressure loss with a simple and compact structure. It becomes possible.
According to the second aspect of the invention, in addition to the effects of the first aspect, a high mixing ratio between different kinds of fluids can be achieved without a large pressure loss.
[0039]
According to the third aspect of the invention, in addition to the effects of the first or second aspect of the invention, the mixing performance of different types of fluids can be further improved.
[0040]
According to the invention set forth in claim 4, in addition to the effects of the invention set forth in any one of claims 1 to 3, it is possible to further enhance the mixing performance of different kinds of fluids.
[0041]
According to the invention described in claim 5, in addition to the effect of the invention described in any one of claims 1 to 4, the fluid ejected from the nozzle in the vicinity of the nozzle can easily reach the inner wall surface of the duct, and further different types of fluid can be obtained. Fluid mixing performance can be improved.
According to the invention of claim 6, in addition to the effect of the invention of any of claims 1 to 5, dust does not accumulate on the mixing plate. It is possible to prevent troubles such as clogging of the dispersion nozzle 2 due to falling of accumulated dust.
[Brief description of the drawings]
FIG. 1 is a bird's-eye view of a cross section along a gas flow direction of a duct through which a mainstream gas flows, in which a fluid mixing device according to an embodiment of the present invention is incorporated.
FIG. 2 is a cross-sectional view of the duct in FIG. 1 in the gas flow direction (FIG. 2A) and a view taken along the line AA of FIG. 2A viewed from the downstream side of the gas flow G (FIG. )) And BB line arrow view (FIG. 2 (c)).
FIG. 3 shows the relationship between the duct opening ratio, the ammonia concentration fluctuation rate downstream of the mixing plate, and the mixing plate pressure loss when the mixing plates installed in two stages are projected on the same plane in the embodiment of FIG. Things.
FIG. 4 shows the relationship between the ratio h / A of the distance h from the dispersion nozzle to the upstream mixing plate with respect to the duct cross-sectional area A in the embodiment of FIG. 1, and the ammonia concentration fluctuation rate and the mixing plate pressure loss. .
FIG. 5 shows the relationship between the ratio ΔH / A of the interval ΔH between the mixing plates installed in two stages with respect to the cross-sectional area A of the duct in the embodiment of FIG. 1, the ammonia concentration fluctuation rate, and the pressure loss of the mixing plate. .
FIG. 6 is a view showing a gas flow G when a pair of an upstream mixing plate and a downstream mixing plate respectively installed on opposed wall surfaces of a duct are inclined from the inner wall side of the duct to the upstream side in another embodiment of the present invention. FIG. 6A is a view of a cross section taken along the line (FIG. 6A) and FIG. 6A is a view taken along line AA of FIG. 6A (FIG. 6B).
7 is a view (FIG. 7 (a)) of a cross section of a duct in a gas flow direction according to another embodiment of the present invention and a view taken along line AA of FIG. 7 (a) (FIG. 7 (b)). ).
FIG. 8 is a bird's-eye view of a cross section along a gas flow direction of a duct through which a mainstream gas flows, into which a fluid mixing device of the related art is incorporated.
FIG. 9 shows a conventional technique in which the number of dispersion nozzles of FIG. 8 is increased to four.
FIG. 10 shows a conventional technique in which a mixer having a general three-dimensional structure is provided downstream of the dispersion nozzle of FIG. 8 or 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Duct 2 Dispersion nozzle 3 Mixer 4 Upstream mixing plate 5 Downstream mixing plate G Gas flow

Claims

In a fluid mixing device provided with a nozzle for injecting a gas and / or liquid of a different type from the gas in a duct having a rectangular cross section serving as a flow path of a gas,
On a pair of opposed duct inner wall surfaces in the vicinity of the nozzle, each mixing plate is projected from the inner wall surface so as to block a part of the gas flow path in the duct, and further, on the side where the mixing plate is not installed. A fluid mixing device, wherein a mixing plate protrudes from an inner wall surface of a pair of opposed duct inner wall surfaces at a position downstream of the mixing plate so as to block a part of a gas flow path.

The size of the mixing plate was set so that the opening ratio when the mixing plates installed at the two stages of the upstream and downstream sides of the duct were projected on the same plane orthogonal to the gas flow was in the range of 20% to 45%. The fluid mixing device according to claim 1, wherein:

From the nozzle to the cross-sectional area A perpendicular to the gas flow duct (upstream of nozzle) -0.4m / ^{m 2} the percentage h / A of the distance h to the upstream mixing plate ~0.6m / ^{m 2} (nozzle 3. The fluid mixing device according to claim 1, wherein the fluid mixing device is in a range of (downstream side).

The fluid mixing device according to any one of claims 1 to 3, wherein a ratio ΔH / A of an interval ΔH between the mixing plates provided in two stages with respect to the duct cross-sectional area A is set to 0.5 m / m ² or less. .

When the cross-sectional shape orthogonal to the gas flow of the rectangular cross-section duct is rectangular, an upstream mixing plate is installed on the short side of the pair of opposing duct inner surfaces, and on the long side of the pair of opposing duct inner surfaces. The fluid mixing device according to any one of claims 1 to 4, wherein a downstream mixing plate is provided.

The fluid mixing device according to any one of claims 1 to 5, wherein the mixing plate installed on the inner wall of the duct is inclined from the wall toward the upstream of the gas flow.