JP7503913B2 - Denitrification equipment and boilers - Google Patents

Denitrification equipment and boilers Download PDF

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JP7503913B2
JP7503913B2 JP2020022814A JP2020022814A JP7503913B2 JP 7503913 B2 JP7503913 B2 JP 7503913B2 JP 2020022814 A JP2020022814 A JP 2020022814A JP 2020022814 A JP2020022814 A JP 2020022814A JP 7503913 B2 JP7503913 B2 JP 7503913B2
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reducing agent
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JP2021126619A5 (en
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幸宏 森本
心平 戸▲高▼
享平 櫻井
英雄 宮西
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Mitsubishi Heavy Industries Ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/74General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86Catalytic processes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/74General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86Catalytic processes
    • B01D53/90Injecting reactants
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22STEAM GENERATION
    • F22BMETHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00Component parts or details of steam boilers

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Description

本開示は、排ガスに含まれる窒素酸化物を除去する脱硝装置、脱硝装置を備えるボイラに関するものである。 This disclosure relates to a denitration device that removes nitrogen oxides from exhaust gas, and a boiler equipped with a denitration device.

石炭焚きボイラなどの大型のボイラは、中空形状をなして鉛直方向に設置される火炉を有し、火炉壁に複数の燃焼バーナが火炉の周方向に沿って配設される。ボイラは、火炉の鉛直方向上方に煙道が連結され、煙道に蒸気を生成するための熱交換器が配置される。燃焼バーナが火炉内に燃料と空気(酸化性ガス)との混合気を噴射することで火炎が形成され、燃焼ガスが生成されて煙道に流れる。熱交換器は、多数の伝熱管により構成され、燃焼ガスが多数の伝熱管内を流れる水や蒸気を加熱して過熱蒸気が生成される。 Large boilers, such as coal-fired boilers, have a hollow furnace that is installed vertically, and multiple combustion burners are arranged on the furnace wall along the circumferential direction of the furnace. The boiler is connected to a flue vertically above the furnace, and a heat exchanger for generating steam is arranged in the flue. The combustion burner injects a mixture of fuel and air (oxidizing gas) into the furnace to form a flame, and combustion gas is generated and flows into the flue. The heat exchanger is composed of many heat transfer tubes, and the combustion gas heats the water and steam flowing inside the many heat transfer tubes to generate superheated steam.

煙道は、ガスダクトが連結され、ガスダクトに脱硝装置が設けられる。熱交換器で過熱蒸気を生成した排ガスは、脱硝装置により窒素酸化物が除去される。脱硝装置は、排ガスに対してアンモニアなどの還元剤を供給し、排ガスと還元剤が触媒を通過するときに、窒素酸化物と還元剤との反応が促進され、排ガス中の窒素酸化物を除去する。 A gas duct is connected to the flue, and a denitration device is installed in the gas duct. The exhaust gas, which has produced superheated steam in the heat exchanger, has nitrogen oxides removed by the denitration device. The denitration device supplies a reducing agent such as ammonia to the exhaust gas, and when the exhaust gas and reducing agent pass through a catalyst, the reaction between the nitrogen oxides and the reducing agent is promoted, removing the nitrogen oxides in the exhaust gas.

このような脱硝装置としては、下記特許文献に記載されているものがある。特許文献1に記載された排煙脱硝装置は、触媒層の上流側に整流格子を設けることで、排ガスの流速部を均一にするものである。特許文献2に記載された脱硝装置は、アンモニア注入ノズルの上流側に整流板を設け、アンモニアを排ガス中に均一に分布させるものである。 Such denitration devices are described in the following patent documents. The flue gas denitration device described in Patent Document 1 is provided with a flow straightening grid upstream of a catalyst layer to make the flow velocity of the exhaust gas uniform. The denitration device described in Patent Document 2 is provided with a flow straightening plate upstream of an ammonia injection nozzle to distribute ammonia uniformly in the exhaust gas.

特開2004-255324号公報JP 2004-255324 A 特開平09-024246号公報Japanese Patent Application Laid-Open No. 09-024246

煙道を流れて脱硝装置に流入する排ガスは、含有する窒素酸化物の濃度にばらつきがある。燃焼バーナは、火炉内に燃料と空気との混合気を噴射することで燃焼し、上昇する燃焼ガス流を生成する。また、煙道は、ガス通路に熱交換器などがあり、また、途中で屈曲している。そのため、脱硝装置に流入する排ガスは、流入方向に直交する面内で窒素酸化物の濃度がばらつき、脱硝装置による脱硝性能に偏りが生じてしまう。従来、排ガスに含有する窒素酸化物の濃度に応じて還元剤の供給量を調整している。ところが、排ガスに含有する窒素酸化物の濃度は、流入方向に直交する面内でばらつくことから、排ガスに対する還元剤の供給量が少ない領域で、窒素酸化物を十分に除去することができない。一方で、排ガスに対する還元剤の供給量が多すぎる領域で、残留する還元剤が脱硝装置の下流側に流れ、硫黄酸化物と反応して硫安が生成され、排気ダクトを閉塞してしまうという課題がある。 The exhaust gas flowing through the flue and flowing into the denitration device has a variation in the concentration of nitrogen oxides contained therein. The combustion burner injects a mixture of fuel and air into the furnace to burn the mixture and generate an ascending combustion gas flow. In addition, the flue has a heat exchanger and the like in the gas passage and is bent along the way. Therefore, the exhaust gas flowing into the denitration device has a variation in the concentration of nitrogen oxides in a plane perpendicular to the inflow direction, which causes a bias in the denitration performance of the denitration device. Conventionally, the supply amount of the reducing agent is adjusted according to the concentration of nitrogen oxides contained in the exhaust gas. However, since the concentration of nitrogen oxides contained in the exhaust gas varies in a plane perpendicular to the inflow direction, nitrogen oxides cannot be sufficiently removed in an area where the supply amount of the reducing agent to the exhaust gas is small. On the other hand, in an area where the supply amount of the reducing agent to the exhaust gas is too large, the remaining reducing agent flows downstream of the denitration device and reacts with sulfur oxides to generate ammonium sulfate, which causes a problem of clogging the exhaust duct.

本開示は、上述した課題を解決するものであり、性能の向上を図る脱硝装置およびボイラを提供することを目的とする。 The present disclosure aims to solve the above-mentioned problems and provide a denitration device and boiler that improves performance.

上記の目的を達成するための本開示の脱硝装置は、ガス通路に設けられる選択還元型触媒と、前記ガス通路における前記選択還元型触媒よりガス流れ方向の上流側に設けられて前記ガス通路をガス流れ方向に直交する方向の複数の領域に区画する仕切板と、前記ガス通路における前記仕切板と前記選択還元型触媒との間に設けられて前記複数の領域を流れるガスの窒素酸化物濃度に応じた量の還元剤を供給する還元剤供給装置と、を備える。 The denitration device of the present disclosure for achieving the above object includes a selective catalytic reduction catalyst provided in a gas passage, a partition plate provided in the gas passage upstream of the selective catalytic reduction catalyst in the gas flow direction to divide the gas passage into a plurality of regions in a direction perpendicular to the gas flow direction, and a reducing agent supply device provided in the gas passage between the partition plate and the selective catalytic reduction catalyst to supply a reducing agent in an amount corresponding to the nitrogen oxide concentration of the gas flowing through the plurality of regions.

また、本開示のボイラは、鉛直方向に沿って設置される火炉と、前記火炉に配置される燃焼装置と、前記火炉における燃焼ガスの流れ方向の下流側に配置される煙道と、前記煙道に配置される熱交換器と、前記煙道における前記熱交換器より下流側に配置される前記脱硝装置と、を備える。 The boiler disclosed herein also includes a furnace installed vertically, a combustion device disposed in the furnace, a flue disposed downstream of the furnace in the flow direction of the combustion gas, a heat exchanger disposed in the flue, and the denitrification device disposed downstream of the heat exchanger in the flue.

本開示の脱硝装置およびボイラによれば、性能の向上を図ることができる。 The denitration device and boiler disclosed herein can improve performance.

図1は、第1実施形態のボイラを表す概略図である。FIG. 1 is a schematic diagram showing a boiler according to a first embodiment. 図2は、第1実施形態の脱硝装置を表す概略構成図である。FIG. 2 is a schematic diagram showing the configuration of the denitration device according to the first embodiment. 図3は、第1実施形態の脱硝装置の作用を表す概略図である。FIG. 3 is a schematic diagram showing the operation of the denitration device of the first embodiment. 図4は、第1仕切板の配置を表す斜視図である。FIG. 4 is a perspective view showing the arrangement of the first partition plate. 図5は、第2実施形態の脱硝装置を表す概略構成図である。FIG. 5 is a schematic diagram showing the configuration of a denitration device according to the second embodiment. 図6は、第2実施形態の脱硝装置を表す概略平面図である。FIG. 6 is a schematic plan view showing a denitration device according to the second embodiment. 図7は、第3実施形態の脱硝装置を表す概略正面図である。FIG. 7 is a schematic front view showing a denitration device according to the third embodiment. 図8は、第3実施形態の脱硝装置を表す概略平面図である。FIG. 8 is a schematic plan view showing a denitration device according to the third embodiment.

以下に図面を参照して、本開示の好適な実施形態を詳細に説明する。なお、この実施形態により本開示が限定されるものではなく、また、実施形態が複数ある場合には、各実施形態を組み合わせて構成するものも含むものである。また、実施形態における構成要素には、当業者が容易に想定できるもの、実質的に同一のもの、いわゆる均等の範囲のものが含まれる。 Below, a preferred embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the various embodiments. Furthermore, the components in the embodiments include those that a person skilled in the art would easily imagine, those that are substantially the same, and those that are within the so-called equivalent range.

[第1実施形態]
図1は、第1実施形態のボイラを表す概略図である。
[First embodiment]
FIG. 1 is a schematic diagram showing a boiler according to a first embodiment.

[ボイラの構成]
第1実施形態の石炭焚きボイラ10は、石炭(炭素含有固体燃料)を粉砕した微粉炭を微粉燃料として用い、微粉燃料を燃焼バーナにより燃焼させ、燃焼により発生した熱を給水や蒸気と熱交換して過熱蒸気を生成することが可能なボイラである。以降の説明で、上や上方とは鉛直方向上側を示し、下や下方とは鉛直方向下側を示す。
[Boiler configuration]
The coal-fired boiler 10 of the first embodiment is a boiler that uses pulverized coal made by pulverizing coal (carbon-containing solid fuel) as pulverized fuel, burns the pulverized fuel with a combustion burner, and is capable of exchanging heat generated by the combustion with feed water or steam to generate superheated steam. In the following description, up and above refer to the upper side in the vertical direction, and below and below refer to the lower side in the vertical direction.

第1実施形態において、図1に示すように、石炭焚きボイラ10は、火炉11と、燃焼装置12と、燃焼ガス通路13とを有する。火炉11は、四角筒の中空形状をなし、鉛直方向に沿って設置される。火炉11を構成する火炉壁(伝熱管)11aは、複数の蒸発管と、複数の蒸発管を接続するフィンとで構成され、微粉燃料の燃焼により発生した熱を給水や蒸気と熱交換することで、火炉壁の温度上昇を抑制する。 In the first embodiment, as shown in FIG. 1, a coal-fired boiler 10 has a furnace 11, a combustion device 12, and a combustion gas passage 13. The furnace 11 has a hollow rectangular cylinder shape and is installed along the vertical direction. The furnace wall (heat transfer tube) 11a that constitutes the furnace 11 is composed of multiple evaporation tubes and fins that connect the multiple evaporation tubes, and exchanges heat generated by the combustion of pulverized fuel with feed water and steam to suppress the temperature rise of the furnace wall.

燃焼装置12は、火炉壁11aの下部側に設けられる。燃焼装置12は、火炉壁11aに装着された複数の燃焼バーナ21,22,23,24,25を有する。燃焼バーナ21,22,23,24,25は、火炉11の周方向に沿って任意の間隔で配設されたものが1セットとして、鉛直方向に沿って複数段(本実施形態では、5段)配置される。但し、火炉11の形状、一つの段における燃焼バーナの数、燃焼バーナの段数は、この構成に限定されるものではない。 The combustion device 12 is provided on the lower side of the furnace wall 11a. The combustion device 12 has multiple combustion burners 21, 22, 23, 24, 25 attached to the furnace wall 11a. The combustion burners 21, 22, 23, 24, 25 are arranged at arbitrary intervals along the circumferential direction of the furnace 11 as one set, and are arranged in multiple stages (five stages in this embodiment) along the vertical direction. However, the shape of the furnace 11, the number of combustion burners in one stage, and the number of stages of combustion burners are not limited to this configuration.

燃焼バーナ21,22,23,24,25は、微粉炭供給管26,27,28,29,30を介して複数の粉砕機(ミル)31,32,33,34,35に連結される。粉砕機31,32,33,34,35は、図示しないが、例えば、ハウジング内に回転テーブルが駆動回転可能に支持され、回転テーブルの上方に複数のローラが回転テーブルの回転に連動して回転可能に支持されて構成される。石炭が複数のローラと回転テーブルとの間に投入されると、ここで所定の微粉炭の大きさに粉砕され、搬送用ガス(一次空気、酸化性ガス)により分級機に搬送されて所定のサイズ範囲内に分級される。所定のサイズ範囲内に分級された微粉燃料が微粉炭供給管26,27,28,29,30から燃焼バーナ21,22,23,24,25に供給される。 The combustion burners 21, 22, 23, 24, and 25 are connected to a plurality of pulverizers (mills) 31, 32, 33, 34, and 35 via pulverized coal supply pipes 26, 27, 28, 29, and 30. The pulverizers 31, 32, 33, 34, and 35 are, for example, configured such that a rotary table is supported in a housing so as to be driven and rotatable, and a plurality of rollers are supported above the rotary table so as to be rotatable in conjunction with the rotation of the rotary table, although not shown. When coal is fed between the plurality of rollers and the rotary table, it is pulverized to a predetermined pulverized coal size here, and is transported to a classifier by a carrier gas (primary air, oxidizing gas) and classified within a predetermined size range. The pulverized fuel classified within the predetermined size range is supplied to the combustion burners 21, 22, 23, 24, and 25 from the pulverized coal supply pipes 26, 27, 28, 29, and 30.

火炉11は、燃焼バーナ21,22,23,24,25の装着位置に風箱36が設けられ、風箱36に空気ダクト(風道)37の一端部が連結される。空気ダクト37は、他端部に押込通風機(FDF:Forced Draft Fan)38が連結される。火炉11は、燃焼バーナ21,22,23,24,25の装着位置より上方にアディショナル空気ポート39が設けられる。アディショナル空気ポート39に空気ダクト37から分岐したアディショナル空気ダクト40の端部が連結される。 The furnace 11 is provided with a wind box 36 at the mounting positions of the combustion burners 21, 22, 23, 24, and 25, and one end of an air duct (airway) 37 is connected to the wind box 36. The other end of the air duct 37 is connected to a forced draft fan (FDF: Forced Draft Fan) 38. The furnace 11 is provided with an additional air port 39 above the mounting positions of the combustion burners 21, 22, 23, 24, and 25. The end of an additional air duct 40 branching off from the air duct 37 is connected to the additional air port 39.

燃焼ガス通路13は、火炉11の鉛直方向の上部に連結される。燃焼ガス通路13は、燃焼ガスの熱を回収するための熱交換器として、過熱器51,52,53、再熱器54,55、節炭器56が設けられる。過熱器51,52,53、再熱器54,55、節炭器56は、火炉11での燃焼で発生した燃焼ガスと伝熱管を流通する給水や蒸気との間で熱交換を行う。 The combustion gas passage 13 is connected to the vertical upper part of the furnace 11. The combustion gas passage 13 is provided with superheaters 51, 52, 53, reheaters 54, 55, and economizer 56 as heat exchangers for recovering heat from the combustion gas. The superheaters 51, 52, 53, reheaters 54, 55, and economizer 56 exchange heat between the combustion gas generated by combustion in the furnace 11 and the feed water or steam flowing through the heat transfer tubes.

燃焼ガス通路13は、下流側に熱交換を行った燃焼ガスが排出される煙道41が連結される。煙道41は、空気ダクト37との間にエアヒータ(空気予熱器)42が設けられる。空気ダクト37を流れる空気は、煙道41を流れる燃焼ガスとの間で熱交換を行い、燃焼バーナ21,22,23,24,25に供給する燃焼用空気を昇温する。 The combustion gas passage 13 is connected to a flue 41 through which the combustion gas that has undergone heat exchange is discharged downstream. An air heater (air preheater) 42 is provided between the flue 41 and the air duct 37. The air flowing through the air duct 37 exchanges heat with the combustion gas flowing through the flue 41, and heats the combustion air supplied to the combustion burners 21, 22, 23, 24, and 25.

煙道14は、エアヒータ42より上流側の位置に脱硝装置43が設けられる。脱硝装置43は、アンモニア、尿素水等の窒素酸化物(NOx)を還元する作用を有する還元剤を煙道41内に供給する。還元剤が供給された燃焼ガスは、窒素酸化物と還元剤との反応が促進され、燃焼ガス中の窒素酸化物が除去、低減される。煙道41は、下流側にガスダクト44が連結される。ガスダクト44は、エアヒータ42より下流側の位置に電気集塵機などの集塵装置45、誘引通風機(IDF:Induced Draft Fan)46、脱硫装置47などが設けられ、下流端部に煙突48が設けられる。 The flue 14 is provided with a denitration device 43 at a position upstream of the air heater 42. The denitration device 43 supplies a reducing agent, such as ammonia or urea water, that has the effect of reducing nitrogen oxides (NOx), into the flue 41. The combustion gas to which the reducing agent is supplied promotes a reaction between the nitrogen oxides and the reducing agent, and the nitrogen oxides in the combustion gas are removed and reduced. A gas duct 44 is connected to the downstream side of the flue 41. The gas duct 44 is provided with a dust collector 45, such as an electric dust collector, an induced draft fan (IDF) 46, a desulfurization device 47, etc. at a position downstream of the air heater 42, and a chimney 48 is provided at the downstream end.

[ボイラの作用]
複数の粉砕機31,32,33,34,35が駆動すると、生成された微粉燃料が搬送用ガス(一次空気、酸化性ガス)と共に微粉炭供給管26,27,28,29,30を通して燃焼バーナ21,22,23,24,25に供給される。また、煙道14から排出された排ガスとエアヒータ42で熱交換することで加熱された燃焼用空気(酸化性ガス)は、空気ダクト37から風箱36を介して各燃焼バーナ21,22,23,24,25に供給される。すると、燃焼バーナ21,22,23,24,25は、微粉燃料と搬送用ガスとが混合した微粉燃料混合気を火炉11に吹き込むと共に、燃焼用空気を火炉11に吹き込む。このとき、微粉燃料混合気が着火することで火炎が形成される。火炉11内の下部で火炎が生じ、高温の燃焼ガスが上昇し、燃焼ガス通路13に排出される。
[Boiler operation]
When the multiple pulverizers 31, 32, 33, 34, 35 are driven, the generated pulverized fuel is supplied to the combustion burners 21, 22, 23, 24, 25 together with the carrier gas (primary air, oxidizing gas) through the pulverized coal supply pipes 26, 27, 28, 29, 30. In addition, the combustion air (oxidizing gas) heated by heat exchange with the exhaust gas discharged from the flue 14 in the air heater 42 is supplied to each of the combustion burners 21, 22, 23, 24, 25 from the air duct 37 through the wind box 36. Then, the combustion burners 21, 22, 23, 24, 25 blow the pulverized fuel mixture, which is a mixture of the pulverized fuel and the carrier gas, into the furnace 11, and also blow the combustion air into the furnace 11. At this time, the pulverized fuel mixture is ignited to form a flame. A flame is generated in the lower part of the furnace 11 , and high-temperature combustion gas rises and is discharged into the combustion gas passage 13 .

火炉11は、下部の領域Aにて、微粉燃料混合気と燃焼用空気(二次空気、酸化性ガス)とが燃焼して火炎が生じる。火炉11は、領域Aで空気の供給量が微粉炭の供給量に対して理論空気量未満となるように設定されることで、内部が還元雰囲気に保持される。すなわち、微粉炭の燃焼により発生した窒素酸化物(NOx)が火炉11の領域Bで還元され、アディショナル空気ポート39からアディショナル空気が追加供給されることで微粉炭の酸化燃焼が完結され、微粉炭の燃焼によるNOxの発生量が低減される。 In the furnace 11, a pulverized fuel mixture and combustion air (secondary air, oxidizing gas) combust in the lower region A to generate a flame. The furnace 11 maintains a reducing atmosphere inside by setting the amount of air supplied in region A to be less than the theoretical amount of air relative to the amount of pulverized coal supplied. In other words, nitrogen oxides (NOx) generated by the combustion of pulverized coal are reduced in region B of the furnace 11, and the oxidative combustion of the pulverized coal is completed by additionally supplying additional air from the additional air port 39, thereby reducing the amount of NOx generated by the combustion of pulverized coal.

火炉11内を上昇した燃焼ガスは、燃焼ガス通路13に配置される第2過熱器52、第3過熱器53、第1過熱器51、第2再熱器55、第1再熱器54、節炭器56で熱交換する。その後、燃焼ガスは、脱硝装置43により窒素酸化物が還元除去され、ガスダクト44に配置された集塵装置45で粒子状物質が除去され、脱硫装置47にて硫黄酸化物が除去された後、煙突48から大気中に排出される。 The combustion gas that rises inside the furnace 11 exchanges heat in the second superheater 52, the third superheater 53, the first superheater 51, the second reheater 55, the first reheater 54, and the economizer 56, which are arranged in the combustion gas passage 13. The combustion gas then has nitrogen oxides reduced and removed by the denitrification device 43, particulate matter removed by the dust collector 45 arranged in the gas duct 44, and sulfur oxides removed by the desulfurization device 47, before being discharged into the atmosphere from the chimney 48.

[脱硝装置の構成]
図2は、第1実施形態の脱硝装置を表す概略構成図、図3は、第1実施形態の脱硝装置の作用を表す概略図、図4は、第1仕切板の配置を表す斜視図である。
[Configuration of Denitrification Device]
FIG. 2 is a schematic diagram showing the configuration of the denitration device of the first embodiment, FIG. 3 is a schematic diagram showing the operation of the denitration device of the first embodiment, and FIG. 4 is a perspective view showing the arrangement of a first partition plate.

煙道(ガス通路)41は、第1水平煙道部41a、第1鉛直煙道部41b、第2水平煙道部41c、第2鉛直煙道部41d、第3水平煙道部(水平通路)41e、第3鉛直煙道部(鉛直通路)41fが連続して設けられて構成される。煙道41は、第1水平煙道部13aおよび第1鉛直煙道部13bに、過熱器51,52,53、再熱器54,55、節炭器56が配置される。また、煙道41は、第2鉛直煙道部41dから第3水平煙道部41eを介して第3鉛直煙道部41fにかけて脱硝装置43が配置される。 The flue (gas passage) 41 is configured by continuously arranging a first horizontal flue section 41a, a first vertical flue section 41b, a second horizontal flue section 41c, a second vertical flue section 41d, a third horizontal flue section (horizontal passage) 41e, and a third vertical flue section (vertical passage) 41f. The flue 41 has superheaters 51, 52, and 53, reheaters 54 and 55, and a coal economizer 56 arranged in the first horizontal flue section 13a and the first vertical flue section 13b. In addition, the flue 41 has a denitrification device 43 arranged from the second vertical flue section 41d through the third horizontal flue section 41e to the third vertical flue section 41f.

脱硝装置43は、選択還元型触媒61と、複数(本実施形態では、3個)の第1仕切板62,63,64と、還元剤供給装置65とを備える。 The denitrification device 43 includes a selective catalytic reduction catalyst 61, multiple (in this embodiment, three) first partition plates 62, 63, and 64, and a reducing agent supply device 65.

図2から図4に示すように、選択還元型触媒61は、脱硝触媒であって、煙道41の第3鉛直煙道部41fに設けられる。選択還元型触媒61は、排ガスに対してアンモニアや尿素水などの還元剤が供給されることで、還元剤が供給された排ガスを窒素酸化物と還元剤との反応を促進させ、窒素酸化物を還元し、排ガス中の窒素酸化物を除去、低減する。 As shown in Figures 2 to 4, the selective reduction catalyst 61 is a denitration catalyst and is provided in the third vertical flue section 41f of the flue 41. The selective reduction catalyst 61 is supplied with a reducing agent such as ammonia or urea water to the exhaust gas, and promotes a reaction between the nitrogen oxides and the reducing agent in the exhaust gas to which the reducing agent has been supplied, thereby reducing the nitrogen oxides and removing and reducing the nitrogen oxides in the exhaust gas.

第1仕切板62,63,64は、煙道41の第2鉛直煙道部41dと第3水平煙道部41eと第3鉛直煙道部41fにまたがって設けられる。第1仕切板62,63,64は、煙道41における選択還元型触媒61よりガス流れ方向の上流側に設けられる。第1仕切板62,63,64は、煙道41のガス通路をガス流れ方向に直交する幅方向の複数(本実施形態では、4個)の混合通路(領域)70a,70b,70c,70dに区画する。 The first partition plates 62, 63, 64 are provided across the second vertical flue section 41d, the third horizontal flue section 41e, and the third vertical flue section 41f of the flue 41. The first partition plates 62, 63, 64 are provided upstream of the selective reduction catalyst 61 in the flue 41 in the gas flow direction. The first partition plates 62, 63, 64 divide the gas passage of the flue 41 into multiple (four in this embodiment) mixing passages (regions) 70a, 70b, 70c, 70d in the width direction perpendicular to the gas flow direction.

混合通路70a,70b,70c,70dは、第2鉛直煙道部41dと第3水平煙道部41eと第3鉛直煙道部41fにて、ガス流れ方向に沿うと共に、幅方向に並行をなして配置される。ここで、幅方向とは、第3水平煙道部41eのガス流れ方向に直交する水平方向である。また、混合通路70a,70b,70c,70dは、ガス流れ方向の長さLが同じ寸法である。ここで、ガス流れ方向の長さLは、煙道41の中心の長さである。 The mixing passages 70a, 70b, 70c, and 70d are arranged in the second vertical flue section 41d, the third horizontal flue section 41e, and the third vertical flue section 41f along the gas flow direction and parallel to the width direction. Here, the width direction is the horizontal direction perpendicular to the gas flow direction of the third horizontal flue section 41e. In addition, the mixing passages 70a, 70b, 70c, and 70d have the same length L in the gas flow direction. Here, the length L in the gas flow direction is the length of the center of the flue 41.

混合通路70a,70b,70c,70dは、ガス流れ方向に直交する幅方向の長さW1,W2,W3,W4が同じ寸法である。混合通路70a,70b,70c,70dは、ガス流れ方向にて、幅方向の長さW1,W2,W3,W4は一定である。なお、幅方向の長さW1,W2,W3,W4を異なる寸法としてもよい。排ガスが混合通路70a,70b,70c,70dに到達したとき、排ガスは、幅方向で窒素酸化物の濃度にばらつきがある。そのため、混合通路70a,70b,70c,70dにおける幅方向の長さW1,W2,W3,W4は、ガスの窒素酸化物の濃度分布や煙道41のレイアウトなどに応じて適宜設定することが好ましい。 The mixing passages 70a, 70b, 70c, and 70d have the same widthwise lengths W1, W2, W3, and W4 perpendicular to the gas flow direction. The mixing passages 70a, 70b, 70c, and 70d have constant widthwise lengths W1, W2, W3, and W4 in the gas flow direction. The widthwise lengths W1, W2, W3, and W4 may be different. When the exhaust gas reaches the mixing passages 70a, 70b, 70c, and 70d, the exhaust gas has a variation in the nitrogen oxide concentration in the width direction. Therefore, it is preferable to appropriately set the widthwise lengths W1, W2, W3, and W4 of the mixing passages 70a, 70b, 70c, and 70d according to the concentration distribution of nitrogen oxide in the gas and the layout of the flue 41.

また、混合通路70a,70b,70c,70dは、ガス流れ方向の長さLがガス流れ方向に直交する幅方向の長さW1,W2,W3,W4より長い寸法である Further, the length L of the mixing passages 70a, 70b, 70c, and 70d in the gas flow direction is longer than the lengths W1, W2, W3, and W4 in the width direction perpendicular to the gas flow direction .

なお、第1仕切板62,63,64は、煙道41における第2鉛直煙道部41dと第3水平煙道部41eと第3鉛直煙道部41fの形状に合わせた形状としている。そのため、第2鉛直煙道部41dと第3水平煙道部41eと第3鉛直煙道部41fの形状が変われば、第1仕切板62,63,64形状も変わる。また、第1仕切板62,63,64は、第2鉛直煙道部41dと第3水平煙道部41eと第3鉛直煙道部41fにまたがっているが、第3鉛直煙道部41fだけに設けたり、第3水平煙道部41eと第3鉛直煙道部41fだけに設けたり、第3水平煙道部41eだけに設けたりしてもよい。更に、第1仕切板62,63,64の数は、3個に限らず、1個であったり、4個以上であったりしてもよい。 The first partition plates 62, 63, and 64 are shaped to match the shapes of the second vertical flue section 41d, the third horizontal flue section 41e, and the third vertical flue section 41f in the flue 41. Therefore, if the shapes of the second vertical flue section 41d, the third horizontal flue section 41e, and the third vertical flue section 41f change, the shapes of the first partition plates 62, 63, and 64 also change. In addition, the first partition plates 62, 63, and 64 straddle the second vertical flue section 41d, the third horizontal flue section 41e, and the third vertical flue section 41f, but they may be provided only in the third vertical flue section 41f, only in the third horizontal flue section 41e and the third vertical flue section 41f, or only in the third horizontal flue section 41e. Furthermore, the number of first partition plates 62, 63, 64 is not limited to three, but may be one, four or more.

還元剤供給装置65は、煙道41の第3鉛直煙道部41fであって、第1仕切板62,63,64と選択還元型触媒61との間に設けられる。すなわち、還元剤供給装置65は、第1仕切板62,63,64より下流側で、選択還元型触媒61より上流側に配置される。還元剤供給装置65は、アンモニアや尿素水などの窒素酸化物を還元する作用を有する還元剤を第3鉛直煙道部41fに供給する。 The reducing agent supplying device 65 is provided in the third vertical flue section 41f of the flue 41 between the first partition plates 62, 63, 64 and the selective reduction catalyst 61. That is, the reducing agent supplying device 65 is disposed downstream of the first partition plates 62, 63, 64 and upstream of the selective reduction catalyst 61. The reducing agent supplying device 65 supplies a reducing agent that has the effect of reducing nitrogen oxides, such as ammonia or urea water, to the third vertical flue section 41f.

還元剤供給装置65は、還元剤供給ポンプ71と、複数(本実施形態では、4個)の還元剤供給管72a,72b,72c,72dとを有する。還元剤供給管72a,72b,72c,72dは、第3鉛直煙道部41fに配置される。還元剤供給管72a,72b,72c,72dは、複数のノズル73a,73b,73c,73dが装着される。複数のノズル73a,73b,73c,73dは、ガス流れ方向の下流側に向けて配置するが、ガス流れ方向の上流側に向けて配置してもよい。還元剤供給管72a,72b,72c,72dは、端部に還元剤供給ポンプ71が連結される。 The reducing agent supply device 65 has a reducing agent supply pump 71 and multiple (four in this embodiment) reducing agent supply pipes 72a, 72b, 72c, 72d. The reducing agent supply pipes 72a, 72b, 72c, 72d are arranged in the third vertical flue section 41f. The reducing agent supply pipes 72a, 72b, 72c, 72d are fitted with multiple nozzles 73a, 73b, 73c, 73d. The multiple nozzles 73a, 73b, 73c, 73d are arranged facing the downstream side of the gas flow direction, but may be arranged facing the upstream side of the gas flow direction. The reducing agent supply pump 71 is connected to the end of the reducing agent supply pipes 72a, 72b, 72c, 72d.

還元剤供給管72a,72b,72c,72dおよびノズル73a,73b,73c,73dは、混合通路70a,70b,70c,70dに対応して配置される。還元剤供給装置65は、混合通路70a,70b,70c,70dの出口部に配置され、混合通路70a,70b,70c,70dから排出された排ガスに対して還元剤を供給し、選択還元型触媒61に流入する前の排ガスに還元剤を拡散させる。なお、還元剤としては、アンモニア水、気体のアンモニア、尿素水などを用いることができる。 The reducing agent supply pipes 72a, 72b, 72c, 72d and the nozzles 73a, 73b, 73c, 73d are arranged corresponding to the mixing passages 70a, 70b, 70c, 70d. The reducing agent supply device 65 is arranged at the outlet of the mixing passages 70a, 70b, 70c, 70d, supplies reducing agent to the exhaust gas discharged from the mixing passages 70a, 70b, 70c, 70d, and diffuses the reducing agent into the exhaust gas before it flows into the selective reduction catalyst 61. The reducing agent may be ammonia water, gaseous ammonia, urea water, or the like.

還元剤供給装置65は、制御装置66が接続される。制御装置66は、還元剤供給装置65を制御することで、混合通路70a,70b,70c,70dを流れる排ガスの窒素酸化物の濃度に応じた量の還元剤を供給する。この場合、混合通路70a,70b,70c,70dを流れる排ガスの窒素酸化物の濃度を、事前の実験、計測、推定などにより求めておくことが望ましい。また、混合通路70a,70b,70c,70dに排ガスの窒素酸化物の濃度を計測する計測器を設け、オンラインで窒素酸化物の濃度を計測してもよい。ここで、制御装置66は、排ガスの窒素酸化物のモル数と供給する還元剤のモル数が同じになる(モル比=1.0)ように、還元剤供給装置65が混合通路70a,70b,70c,70dに供給する還元剤の供給量を調整する。 The reducing agent supply device 65 is connected to a control device 66. The control device 66 controls the reducing agent supply device 65 to supply an amount of reducing agent according to the concentration of nitrogen oxides in the exhaust gas flowing through the mixing passages 70a, 70b, 70c, and 70d. In this case, it is desirable to obtain the concentration of nitrogen oxides in the exhaust gas flowing through the mixing passages 70a, 70b, 70c, and 70d in advance by experiments, measurements, estimations, etc. In addition, a measuring device for measuring the concentration of nitrogen oxides in the exhaust gas may be provided in the mixing passages 70a, 70b, 70c, and 70d, and the concentration of nitrogen oxides may be measured online. Here, the control device 66 adjusts the supply amount of reducing agent supplied by the reducing agent supply device 65 to the mixing passages 70a, 70b, 70c, and 70d so that the number of moles of nitrogen oxides in the exhaust gas and the number of moles of the reducing agent supplied are the same (molar ratio = 1.0) .

[脱硝装置の作用]
脱硝装置43において、図2および図3に示すように、煙道41を流れる排ガスは、第2鉛直煙道部41dを上昇した後、第3水平煙道部41eを水平方向に流れ、第3鉛直煙道部41fを下降する。このとき、排ガスは、第1仕切板62,63,64により幅方向に区画された4個の混合通路70a,70b,70c,70dに分配され、混合通路70a,70b,70c,70dを所定の長さLだけ流れる。
[Function of Denitrification Device]
2 and 3, in the denitration device 43, the flue gas flowing through the flue 41 ascends through the second vertical flue section 41d, then flows horizontally through the third horizontal flue section 41e, and descends through the third vertical flue section 41f. At this time, the flue gas is distributed to four mixing passages 70a, 70b, 70c, and 70d partitioned in the width direction by first partition plates 62, 63, and 64, and flows through the mixing passages 70a, 70b, 70c, and 70d for a predetermined length L.

煙道41を流れる排ガスは、燃焼ガス通路13で生成される燃焼ガス流の旋回流、煙道41に配置される熱交換器、煙道41の途中形状などにより、例えば、幅方向で排ガスに含有する窒素酸化物の濃度にばらつきがある。例えば、排ガスに含有する窒素酸化物の濃度C0(図3参照)は、混合通路70a,70b,70c,70dの上流側にて、幅方向における混合通路70a側で低く、混合通路70d側に行くほど高くなる。 The exhaust gas flowing through the flue 41 has a variation in the concentration of nitrogen oxides contained in the exhaust gas, for example, in the width direction, due to the swirling flow of the combustion gas flow generated in the combustion gas passage 13, the heat exchanger arranged in the flue 41, the shape of the flue 41, etc. For example, the concentration C0 of nitrogen oxides contained in the exhaust gas (see FIG. 3) is low on the mixing passage 70a side in the width direction upstream of the mixing passages 70a, 70b, 70c, and 70d, and increases toward the mixing passage 70d side.

煙道41の幅方向で窒素酸化物の濃度差がある排ガスは、混合通路70a,70b,70c,70dに流入し、混合通路70a,70b,70c,70dを所定の長さLだけ流れる間に混合される。そして、混合通路70a,70b,70c,70dを個別に流れた排ガスは、混合通路70a,70b,70c,70dの出口部で、窒素酸化物の濃度差がほぼ均一となる。すなわち、第1仕切板62,63,64が配置されていない幅の広い煙道では、排ガスが所定の長さLだけ流れても十分に混合されず、幅方向で窒素酸化物の濃度差が生じる。一方、第1仕切板62,63,64で区画された幅の狭い混合通路70a,70b,70c,70dでは、排ガスが所定の長さLだけ流れる間に十分に混合され、幅方向で窒素酸化物の濃度差が生じにくい。混合通路70a,70b,70c,70dをそれぞれ流れた排ガス同士を比較すると、排ガスに含有する窒素酸化物の濃度C1,C2,C3,C4(図3参照)に濃度差(C1<C2<C3<C4)がある。しかし、混合通路70a,70b,70c,70dを流れたそれぞれの排ガスだけを幅方向で比較すると、排ガスに含有する窒素酸化物の濃度C1,C2,C3,C4(図3参照)は、幅方向でほとんど濃度差がない。 The exhaust gas having a difference in nitrogen oxide concentration in the width direction of the flue 41 flows into the mixing passages 70a, 70b, 70c, 70d and is mixed while flowing through the mixing passages 70a, 70b, 70c, 70d for a predetermined length L. Then, the exhaust gas flowing through the mixing passages 70a, 70b, 70c, 70d individually has a substantially uniform difference in nitrogen oxide concentration at the outlet of the mixing passages 70a, 70b, 70c, 70d. That is, in a wide flue where the first partition plates 62, 63, 64 are not arranged, the exhaust gas is not sufficiently mixed even if it flows for the predetermined length L, and a difference in nitrogen oxide concentration occurs in the width direction. On the other hand, in the narrow mixing passages 70a, 70b, 70c, 70d partitioned by the first partition plates 62, 63, 64, the exhaust gas is sufficiently mixed while flowing for the predetermined length L, and a difference in nitrogen oxide concentration is unlikely to occur in the width direction. When the exhaust gases that have flowed through the mixing passages 70a, 70b, 70c, and 70d are compared, there is a difference in the concentrations C1, C2, C3, and C4 (see FIG. 3) of nitrogen oxides contained in the exhaust gases. However, when the exhaust gases that have flowed through the mixing passages 70a, 70b, 70c, and 70d are compared in the width direction, there is almost no difference in the concentrations C1, C2, C3, and C4 (see FIG. 3) of nitrogen oxides contained in the exhaust gases.

混合通路70a,70b,70c,70dを流れる排ガスは、第3鉛直煙道部41fに排出されると、還元剤供給装置65から還元剤が供給される。このとき、制御装置66は、還元剤供給装置65を制御することで、混合通路70a,70b,70c,70dを流れる排ガスに対して、含有する窒素酸化物の濃度に応じた量の還元剤を供給する。すなわち、混合通路70a,70b,70c,70dから排出されて窒素酸化物の濃度C1,C2,C3,C4が異なる排ガスに対して、還元剤供給管72a,72b,72c,72dのノズル73a,73b,73c,73dから異なる量の還元剤を噴射する。具体的には、混合通路70aから排出されて窒素酸化物の濃度が低い排ガスに対して還元剤供給管72aのノズル73aから最小量の還元剤を噴射する。一方、混合通路70dから排出されて窒素酸化物の濃度が高い排ガスに対して還元剤供給管72dのノズル73dから最大量の還元剤を噴射する。 When the exhaust gas flowing through the mixing passages 70a, 70b, 70c, and 70d is discharged into the third vertical flue section 41f, a reducing agent is supplied from the reducing agent supply device 65. At this time, the control device 66 controls the reducing agent supply device 65 to supply an amount of reducing agent corresponding to the concentration of nitrogen oxides contained in the exhaust gas flowing through the mixing passages 70a, 70b, 70c, and 70d. That is, different amounts of reducing agent are injected from the nozzles 73a, 73b, 73c, and 73d of the reducing agent supply pipes 72a, 72b, 72c, and 72d to exhaust gases discharged from the mixing passages 70a, 70b, 70c, and 70d and having different concentrations C1, C2, C3, and C4 of nitrogen oxides. Specifically, the minimum amount of reducing agent is injected from the nozzle 73a of the reducing agent supply pipe 72a to exhaust gas discharged from the mixing passage 70a and having a low concentration of nitrogen oxides. On the other hand, the maximum amount of reducing agent is injected from the nozzle 73d of the reducing agent supply pipe 72d into the exhaust gas discharged from the mixing passage 70d and having a high concentration of nitrogen oxides.

排ガスに対して還元剤供給装置65から還元剤が供給されると、排ガスは、還元剤が混合された状態で選択還元型触媒61に流入する。選択還元型触媒61は、排ガスの窒素酸化物と還元剤との反応を促進させ、窒素酸化物を還元し、排ガス中の窒素酸化物を除去、低減する。このとき、濃度C1,C2,C3,C4が異なる排ガスに対して、窒素酸化物の含有量に応じた量の還元剤が供給されてから選択還元型触媒61に流入するため、選択還元型触媒61により窒素酸化物が効率良く還元除去される。すなわち、排ガスに対する還元剤の供給量が少なく、窒素酸化物の除去が不十分になることが抑制される。また、排ガスに対する還元剤の供給量が多く、残った還元剤が硫黄酸化物と反応して硫安が生成することが抑制される。 When the reducing agent is supplied from the reducing agent supply device 65 to the exhaust gas, the exhaust gas flows into the selective reduction catalyst 61 in a state where the reducing agent is mixed therein. The selective reduction catalyst 61 promotes the reaction between the nitrogen oxides in the exhaust gas and the reducing agent, reduces the nitrogen oxides, and removes and reduces the nitrogen oxides in the exhaust gas. At this time, the reducing agent is supplied in an amount according to the nitrogen oxide content to the exhaust gas having different concentrations C1, C2, C3, and C4, and then the exhaust gas flows into the selective reduction catalyst 61, so that the selective reduction catalyst 61 efficiently reduces and removes the nitrogen oxides. That is, the amount of reducing agent supplied to the exhaust gas is small, which prevents the removal of the nitrogen oxides from becoming insufficient . In addition, the amount of reducing agent supplied to the exhaust gas is large, which prevents the remaining reducing agent from reacting with the sulfur oxides to generate ammonium sulfate.

[第2実施形態]
図5は、第2実施形態の脱硝装置を表す概略構成図、図6は、第2実施形態の脱硝装置を表す概略平面図である。なお、上述した第1実施形態と同様の機能を有する部材には、同一の符号を付して詳細な説明は省略する。
[Second embodiment]
Fig. 5 is a schematic configuration diagram showing a denitration device of the second embodiment, and Fig. 6 is a schematic plan view showing the denitration device of the second embodiment. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed description thereof will be omitted.

第2実施形態において、図5および図6に示すように、脱硝装置43Aは、選択還元型触媒61と、複数の第1仕切板62,63,64と、還元剤供給装置65と、混合促進装置81とを備える。ここで、選択還元型触媒61と第1仕切板62,63,64と還元剤供給装置65は、第1実施形態と同様であることから、詳細な説明は省略する。 In the second embodiment, as shown in Figs. 5 and 6, the denitration device 43A includes a selective reduction catalyst 61, a plurality of first partition plates 62, 63, and 64, a reducing agent supply device 65, and a mixing promotion device 81. Here, the selective reduction catalyst 61, the first partition plates 62, 63, and 64, and the reducing agent supply device 65 are the same as those in the first embodiment, so detailed description is omitted.

選択還元型触媒61は、煙道41の第3鉛直煙道部41fに設けられる。第1仕切板62,63,64は、煙道41の第2鉛直煙道部41dと第3水平煙道部41eと第3鉛直煙道部41fにまたがって設けられる。第1仕切板62,63,64は、煙道41における選択還元型触媒61よりガス流れ方向の上流側に設けられる。第1仕切板62,63,64は、煙道41のガス通路をガス流れ方向に直交する幅方向の4個の混合通路70a,70b,70c,70dに区画する。還元剤供給装置65は、煙道41の第3鉛直煙道部41fであって、第1仕切板62,63,64と選択還元型触媒61との間に設けられる。 The selective reduction catalyst 61 is provided in the third vertical flue section 41f of the flue 41. The first partition plates 62, 63, 64 are provided across the second vertical flue section 41d, the third horizontal flue section 41e, and the third vertical flue section 41f of the flue 41. The first partition plates 62, 63, 64 are provided upstream of the selective reduction catalyst 61 in the flue 41 in the gas flow direction. The first partition plates 62, 63, 64 divide the gas passage of the flue 41 into four mixing passages 70a, 70b, 70c, 70d in the width direction perpendicular to the gas flow direction. The reducing agent supply device 65 is provided in the third vertical flue section 41f of the flue 41 between the first partition plates 62, 63, 64 and the selective reduction catalyst 61.

混合促進装置81は、第1仕切板62,63,64により区画された4個の混合通路70a,70b,70c,70dにおけるガス流入部に設けられる。混合促進装置81は、複数(本実施例では、4個)の混合促進器81a,81b,81c,81dを有する。混合促進器81a,81b,81c,81dは、第1仕切板62,63,64により区画された4個の混合通路70a,70b,70c,70dにおけるガス流れ方向の上流側端部に配置される。つまり、混合促進器81a,81b,81c,81dは、第1仕切板62,63,64におけるガス流れ方向の上流側端部に挟まれた位置に配置される。 The mixing promotion device 81 is provided at the gas inlet portion of the four mixing passages 70a, 70b, 70c, and 70d partitioned by the first partition plates 62, 63, and 64. The mixing promotion device 81 has multiple (four in this embodiment) mixing promoters 81a, 81b, 81c, and 81d. The mixing promoters 81a, 81b, 81c, and 81d are arranged at the upstream ends of the four mixing passages 70a, 70b, 70c, and 70d partitioned by the first partition plates 62, 63, and 64 in the gas flow direction. In other words, the mixing promoters 81a, 81b, 81c, and 81d are arranged at positions sandwiched between the upstream ends of the first partition plates 62, 63, and 64 in the gas flow direction.

混合促進装置81(混合促進器81a,81b,81c,81d)は、例えば、旋回流発生装置であり、混合通路70a,70b,70c,70dに流入した排ガスに旋回力を付与する。混合通路70a,70b,70c,70dに流入した排ガスは、旋回力が付与されることで混合が促進され、窒素酸化物の濃度差がなくなり、幅方向や高さ方向における窒素酸化物の濃度が均一になる。 The mixing promotion device 81 (mixing promoters 81a, 81b, 81c, 81d) is, for example, a swirling flow generating device that imparts a swirling force to the exhaust gas that flows into the mixing passages 70a, 70b, 70c, 70d. The mixing of the exhaust gas that flows into the mixing passages 70a, 70b, 70c, 70d is promoted by the swirling force, eliminating the difference in nitrogen oxide concentration and making the nitrogen oxide concentration uniform in the width direction and height direction.

なお、混合促進装置81は、旋回流発生装置に限定されるものではない。例えば、排ガスが衝突する複数の抵抗板を設け、混合通路70a,70b,70c,70dに乱流を形成するものであってもよいし、その他の装置であってもよい。また、混合促進器81a,81b,81c,81dを混合通路70a,70b,70c,70dの上流側端部に配置したが、混合通路70a,70b,70c,70d内ではなく、混合通路70a,70b,70c,70dの直上流側に配置してもよい。 The mixing promoter 81 is not limited to a swirling flow generating device. For example, it may be a device that provides multiple resistance plates against which the exhaust gas collides to form turbulent flow in the mixing passages 70a, 70b, 70c, and 70d, or it may be another device. In addition, the mixing promoters 81a, 81b, 81c, and 81d are disposed at the upstream ends of the mixing passages 70a, 70b, 70c, and 70d, but they may also be disposed immediately upstream of the mixing passages 70a, 70b, 70c, and 70d, rather than within the mixing passages 70a, 70b, 70c, and 70d.

そのため、脱硝装置43Aにおいて、煙道41を流れる排ガスは、第2鉛直煙道部41dを上昇した後、第3水平煙道部41eを水平方向に流れ、第3鉛直煙道部41fを下降する。このとき、排ガスは、第1仕切板62,63,64により幅方向に区画された4個の混合通路70a,70b,70c,70dに分配される。そして、排ガスは、混合通路70a,70b,70c,70dに流入するとき、混合促進器81a,81b,81c,81dにより旋回力が付与されることで混合が促進され、混合通路70a,70b,70c,70dで窒素酸化物の濃度差が低減される。そして、混合通路70a,70b,70c,70dを所定の長さLだけ流れた排ガスは、混合通路70a,70b,70c,70dの出口部で、窒素酸化物の濃度差がほぼ均一となる。 Therefore, in the denitrification device 43A, the exhaust gas flowing through the flue 41 rises through the second vertical flue section 41d, then flows horizontally through the third horizontal flue section 41e, and then descends through the third vertical flue section 41f. At this time, the exhaust gas is distributed to four mixing passages 70a, 70b, 70c, and 70d, which are partitioned in the width direction by the first partition plates 62, 63, and 64. When the exhaust gas flows into the mixing passages 70a, 70b, 70c, and 70d, a swirling force is applied by the mixing promoters 81a, 81b, 81c, and 81d to promote mixing, and the concentration difference of nitrogen oxides is reduced in the mixing passages 70a, 70b, 70c, and 70d. Then, after the exhaust gas flows through the mixing passages 70a, 70b, 70c, and 70d for a predetermined length L, the concentration difference of nitrogen oxides becomes almost uniform at the outlets of the mixing passages 70a, 70b, 70c, and 70d.

混合通路70a,70b,70c,70dから第3鉛直煙道部41fに排出された排ガスに対して、還元剤供給装置65から還元剤が供給される。このとき、制御装置66は、還元剤供給装置65を制御することで、混合通路70a,70b,70c,70dを流れる排ガスに対して、含有する窒素酸化物の濃度に応じた量の還元剤を供給する。すると、排ガスは、還元剤が混合された状態で選択還元型触媒61に流入する。選択還元型触媒61は、排ガスの窒素酸化物と還元剤との反応を促進させ、窒素酸化物を還元し、排ガス中の窒素酸化物を除去、低減する。このとき、濃度が異なる排ガスに対して、窒素酸化物の含有量に応じた量の還元剤が供給されてから選択還元型触媒61に流入するため、選択還元型触媒61により窒素酸化物が効率良く還元除去される。 The reducing agent is supplied from the reducing agent supplying device 65 to the exhaust gas discharged from the mixing passages 70a, 70b, 70c, and 70d to the third vertical flue section 41f. At this time, the control device 66 controls the reducing agent supplying device 65 to supply the reducing agent in an amount corresponding to the concentration of nitrogen oxides contained in the exhaust gas flowing through the mixing passages 70a, 70b, 70c, and 70d. Then, the exhaust gas flows into the selective reduction catalyst 61 in a state where the reducing agent is mixed therein. The selective reduction catalyst 61 promotes the reaction between the nitrogen oxides in the exhaust gas and the reducing agent, reduces the nitrogen oxides, and removes and reduces the nitrogen oxides in the exhaust gas. At this time, the reducing agent is supplied in an amount corresponding to the nitrogen oxide content to the exhaust gas with different concentrations before it flows into the selective reduction catalyst 61, so that the selective reduction catalyst 61 efficiently reduces and removes the nitrogen oxides.

[第3実施形態]
図7は、第3実施形態の脱硝装置を表す概略正面図、図8は、第3実施形態の脱硝装置を表す概略平面図である。なお、上述した第1実施形態と同様の機能を有する部材には、同一の符号を付して詳細な説明は省略する。
[Third embodiment]
Fig. 7 is a schematic front view showing a denitration device of the third embodiment, and Fig. 8 is a schematic plan view showing the denitration device of the third embodiment. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed description thereof will be omitted.

第3実施形態において、図7および図8に示すように、脱硝装置43Bは、選択還元型触媒61と、複数(本実施形態では、3個)の第2仕切板91,92,93と、還元剤供給装置65とを備える。ここで、選択還元型触媒61と還元剤供給装置65は、第1実施形態と同様であることから、詳細な説明は省略する。 In the third embodiment, as shown in Figures 7 and 8, the denitration device 43B includes a selective reduction catalyst 61, a plurality of (three in this embodiment) second partition plates 91, 92, and 93, and a reducing agent supply device 65. Here, the selective reduction catalyst 61 and the reducing agent supply device 65 are similar to those in the first embodiment, and therefore detailed description thereof will be omitted.

選択還元型触媒61は、脱硝触媒であって、煙道41の第3鉛直煙道部41fに設けられる。 The selective reduction catalyst 61 is a denitrification catalyst and is provided in the third vertical flue section 41f of the flue 41.

第2仕切板91,92,93は、煙道41の第3鉛直煙道部41fに設けられる。第2仕切板91,92,93は、煙道41における選択還元型触媒61よりガス流れ方向の上流側に設けられる。第2仕切板91,92,93は、煙道41のガス通路をガス流れ方向に直交する奥行方向の複数(本実施形態では、4個)の混合通路(領域)94a,94b,94c,94dに区画する。 The second partition plates 91, 92, and 93 are provided in the third vertical flue section 41f of the flue 41. The second partition plates 91, 92, and 93 are provided upstream of the selective reduction catalyst 61 in the flue 41 in the gas flow direction. The second partition plates 91, 92, and 93 divide the gas passage of the flue 41 into multiple (four in this embodiment) mixing passages (regions) 94a, 94b, 94c, and 94d in the depth direction perpendicular to the gas flow direction.

混合通路94a,94b,94c,94dは、第3鉛直煙道部41fにて、ガス流れ方向に沿うと共に、奥行方向に並行をなして配置される。ここで、奥行方向とは、第3鉛直煙道部41fのガス流れ方向および幅方向に直交する水平方向(図7の左右方向)である。また、混合通路94a,94bは、ガス流れ方向の長さが同じ寸法であり、混合通路94c,94dにおけるガス流れ方向の長さ(鉛直方向の長さ)は、第3鉛直煙道部41fの天井部が傾斜によらず、煙道41のレイアウト、脱硝効率、要求性能などを考慮した適切な長さでよい。 The mixing passages 94a, 94b, 94c, and 94d are arranged in the third vertical flue section 41f along the gas flow direction and parallel to the depth direction. Here, the depth direction is the horizontal direction (left and right direction in FIG. 7) perpendicular to the gas flow direction and width direction of the third vertical flue section 41f. The mixing passages 94a and 94b have the same length in the gas flow direction, and the length in the gas flow direction (vertical length) of the mixing passages 94c and 94d may be an appropriate length taking into consideration the layout of the flue 41, the denitration efficiency, the required performance, and the like, regardless of the inclination of the ceiling part of the third vertical flue section 41f.

なお、第2仕切板91,92,93を煙道41における第3鉛直煙道部41fに設けたが、第2鉛直煙道部41dや第3水平煙道部41eに設けてもよい。 The second partition plates 91, 92, and 93 are provided in the third vertical flue section 41f of the flue 41, but they may also be provided in the second vertical flue section 41d or the third horizontal flue section 41e.

還元剤供給装置65は、煙道41の第3鉛直煙道部41fであって、仕切板91,92,93と選択還元型触媒61との間に設けられる。すなわち、還元剤供給装置65は、仕切板91,92,93より下流側で、選択還元型触媒61より上流側である。還元剤供給装置65は、アンモニアや尿素水などの窒素酸化物を還元する作用を有する還元剤を第3鉛直煙道部41fに供給する。 The reducing agent supplying device 65 is provided in the third vertical flue section 41f of the flue 41 between the partition plates 91, 92, 93 and the selective reduction catalyst 61. That is, the reducing agent supplying device 65 is downstream of the partition plates 91, 92, 93 and upstream of the selective reduction catalyst 61. The reducing agent supplying device 65 supplies a reducing agent that has the effect of reducing nitrogen oxides, such as ammonia or urea water, to the third vertical flue section 41f.

還元剤供給管72a,72b,72c,72dおよびノズル73a,73b,73c,73dは、混合通路94a,94b,94c,94dに対応して配置される。還元剤供給装置65は、混合通路94a,94b,94c,94dの出口部に配置され、混合通路94a,94b,94c,94dから排出された排ガスに対して還元剤を供給し、選択還元型触媒61に流入する前の排ガスに還元剤を拡散させる。 The reducing agent supply pipes 72a, 72b, 72c, and 72d and the nozzles 73a, 73b, 73c, and 73d are arranged corresponding to the mixing passages 94a, 94b, 94c, and 94d. The reducing agent supply device 65 is arranged at the outlet of the mixing passages 94a, 94b, 94c, and 94d, and supplies reducing agent to the exhaust gas discharged from the mixing passages 94a, 94b, 94c, and 94d, and diffuses the reducing agent into the exhaust gas before it flows into the selective reduction catalyst 61.

還元剤供給装置65は、制御装置66が接続される。制御装置66は、還元剤供給装置65を制御することで、混合通路94a,94b,94c,94dを流れる排ガスの窒素酸化物の濃度に応じた量の還元剤を供給する。ここで、制御装置66は、排ガスの窒素酸化物のモル数と供給する還元剤のモル数が同じになる(モル比=1.0)ように、還元剤供給装置65が混合通路94a,94b,94c,94dに供給する還元剤の供給量を調整する。 A control device 66 is connected to the reducing agent supply device 65. The control device 66 controls the reducing agent supply device 65 to supply an amount of reducing agent according to the concentration of nitrogen oxides in the exhaust gas flowing through the mixing passages 94a, 94b, 94c, and 94d. Here, the control device 66 adjusts the supply amount of reducing agent supplied by the reducing agent supply device 65 to the mixing passages 94a, 94b, 94c, and 94d so that the number of moles of nitrogen oxides in the exhaust gas and the number of moles of the reducing agent supplied are the same (molar ratio = 1.0).

そのため、脱硝装置43Bにおいて、煙道41を流れる排ガスは、第3鉛直煙道部41fを下降し、第2仕切板91,92,93により奥行方向に区画された4個の混合通路94a,94b,94c,94dに分配され、混合通路94a,94b,94c,94dを所定の長さだけ流れる。 Therefore, in the denitrification device 43B, the exhaust gas flowing through the flue 41 descends the third vertical flue section 41f, is distributed to four mixing passages 94a, 94b, 94c, and 94d partitioned in the depth direction by the second partition plates 91, 92, and 93, and flows through the mixing passages 94a, 94b, 94c, and 94d for a predetermined length.

煙道41の高さ(奥行)方向で窒素酸化物の濃度差がある排ガスは、混合通路94a,94b,94c,94dに流入し、混合通路94a,94b,94c,94dを所定の長さだけ流れる間に混合される。そして、混合通路94a,94b,94c,94dを個別に流れた排ガスは、混合通路94a,94b,94c,94dの出口部で、窒素酸化物の濃度差がほぼ均一となる。すなわち、混合通路94a,94b,94c,94dをそれぞれ流れた排ガス同士を比較すると、排ガスに含有する窒素酸化物の濃度に差がある。しかし、混合通路94a,94b,94c,94dを流れたそれぞれの排ガスだけを幅方向で比較すると、排ガスに含有する窒素酸化物の濃度は、奥行方向でほとんど濃度差がない。 Exhaust gas with a difference in nitrogen oxide concentration in the height (depth) direction of the flue 41 flows into the mixing passages 94a, 94b, 94c, and 94d, and is mixed while flowing through the mixing passages 94a, 94b, 94c, and 94d for a certain length. Then, the difference in nitrogen oxide concentration of the exhaust gas that flows through the mixing passages 94a, 94b, 94c, and 94d individually becomes almost uniform at the outlet of the mixing passages 94a, 94b, 94c, and 94d. In other words, when comparing the exhaust gases that flow through the mixing passages 94a, 94b, 94c, and 94d, respectively, there is a difference in the concentration of nitrogen oxide contained in the exhaust gas. However, when comparing only the exhaust gases that flow through the mixing passages 94a, 94b, 94c, and 94d in the width direction, there is almost no difference in the concentration of nitrogen oxide contained in the exhaust gas in the depth direction.

混合通路94a,94b,94c,94dを流れる排ガスは、第3鉛直煙道部41fに排出されると、還元剤供給装置65から還元剤が供給される。このとき、制御装置66は、還元剤供給装置65を制御することで、混合通路94a,94b,94c,94dを流れる排ガスに対して、含有する窒素酸化物の濃度に応じた量の還元剤を供給する。すなわち、混合通路94a,94b,94c,94dから排出されて窒素酸化物の濃度が異なる排ガスに対して、還元剤供給管72a,72b,72c,72dのノズル73a,73b,73c,73dから異なる量の還元剤を噴射する。具体的には、混合通路94aから排出されて窒素酸化物の濃度が低い排ガスに対して還元剤供給管72aのノズル73aから最小量の還元剤を噴射する。一方、混合通路70dから排出されて窒素酸化物の濃度が高い排ガスに対して還元剤供給管72dのノズル73dから最大量の還元剤を噴射する。 When the exhaust gas flowing through the mixing passages 94a, 94b, 94c, and 94d is discharged into the third vertical flue section 41f, a reducing agent is supplied from the reducing agent supply device 65. At this time, the control device 66 controls the reducing agent supply device 65 to supply an amount of reducing agent corresponding to the concentration of nitrogen oxides contained in the exhaust gas flowing through the mixing passages 94a, 94b, 94c, and 94d. That is, different amounts of reducing agent are injected from the nozzles 73a, 73b, 73c, and 73d of the reducing agent supply pipes 72a, 72b, 72c, and 72d to exhaust gases discharged from the mixing passages 94a, 94b, 94c, and 94d and having different concentrations of nitrogen oxides. Specifically, the minimum amount of reducing agent is injected from the nozzle 73a of the reducing agent supply pipe 72a to exhaust gas discharged from the mixing passage 94a and having a low concentration of nitrogen oxides. On the other hand, the maximum amount of reducing agent is injected from the nozzle 73d of the reducing agent supply pipe 72d into the exhaust gas discharged from the mixing passage 70d and having a high concentration of nitrogen oxides.

排ガスに対して還元剤供給装置65から還元剤が供給されると、排ガスは、還元剤が混合された状態で選択還元型触媒61に流入する。選択還元型触媒61は、排ガスの窒素酸化物と還元剤との反応を促進させ、窒素酸化物を還元し、排ガス中の窒素酸化物を除去、低減する。このとき、濃度が異なる排ガスに対して、窒素酸化物の含有量に応じた量の還元剤が供給されてから選択還元型触媒61に流入するため、選択還元型触媒61により窒素酸化物が効率良く還元除去される。 When a reducing agent is supplied to the exhaust gas from the reducing agent supply device 65, the exhaust gas flows into the selective reduction catalyst 61 with the reducing agent mixed in. The selective reduction catalyst 61 promotes the reaction between the nitrogen oxides in the exhaust gas and the reducing agent, reducing the nitrogen oxides, and removing and reducing the nitrogen oxides in the exhaust gas. At this time, an amount of reducing agent according to the nitrogen oxide content is supplied to exhaust gases with different concentrations before they flow into the selective reduction catalyst 61, so that the selective reduction catalyst 61 efficiently reduces and removes the nitrogen oxides.

[本実施形態の作用効果]
第1の態様に係る脱硝装置は、煙道(ガス通路)41に設けられる選択還元型触媒61と、煙道41における選択還元型触媒61よりガス流れ方向の上流側に設けられて煙道41をガス流れ方向に直交する方向の複数の混合通路(領域)70a,70b,70c,70d,94a,94b,94c,94dに区画する仕切板62,63,64,91,92,93と、煙道41における仕切板62,63,64,91,92,93と選択還元型触媒61との間に設けられて複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dを流れるガスの窒素酸化物濃度に応じた量の還元剤を供給する還元剤供給装置65とを備える。
[Effects of this embodiment]
The denitration device according to the first aspect includes a selective reduction catalyst 61 provided in a flue (gas passage) 41, partition plates 62, 63, 64, 91, 92, 93 provided in the flue 41 upstream of the selective reduction catalyst 61 in the gas flow direction and dividing the flue 41 into a plurality of mixing passages (regions) 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d in a direction perpendicular to the gas flow direction, and a reducing agent supplying device 65 provided between the partition plates 62, 63, 64, 91, 92, 93 in the flue 41 and the selective reduction catalyst 61 and supplies a reducing agent in an amount corresponding to the nitrogen oxide concentrations of gas flowing through the plurality of mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d.

第1の態様に係る脱硝装置は、煙道41に流れる排ガスは、仕切板62,63,64,91,92,93により区画された複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dを流れた後、還元剤供給装置65により混合通路70a,70b,70c,70d,94a,94b,94c,94dを流れるガスの窒素酸化物濃度に応じた量の還元剤が供給される。そのため、窒素酸化物濃度の高い排ガスに対しては、多量の還元剤が供給され、窒素酸化物濃度の低い排ガスに対しては、小量の還元剤が供給されることとなり、選択還元型触媒61は、排ガス中の窒素酸化物を効率良く還元除去することができ、性能の向上を図ることができる。すなわち、窒素酸化物濃度に応じた適量の還元剤を排ガスに供給するため、窒素酸化物を還元した後に残った還元剤が硫黄酸化物と反応して硫安が生成することが抑制される。そのため、硫安の除去作業などが不要となり、メンテナンスコストの増大を抑制することができる。 In the denitration device according to the first aspect, the exhaust gas flowing into the flue 41 flows through a plurality of mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d partitioned by partition plates 62, 63, 64, 91, 92, 93, and then the reducing agent supply device 65 supplies a reducing agent in an amount corresponding to the nitrogen oxide concentration of the gas flowing through the mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d. Therefore, a large amount of reducing agent is supplied to exhaust gas with a high nitrogen oxide concentration, and a small amount of reducing agent is supplied to exhaust gas with a low nitrogen oxide concentration, so that the selective reduction catalyst 61 can efficiently reduce and remove nitrogen oxides in the exhaust gas, thereby improving performance. In other words, since an appropriate amount of reducing agent corresponding to the nitrogen oxide concentration is supplied to the exhaust gas, the reducing agent remaining after reducing the nitrogen oxides is prevented from reacting with sulfur oxides to produce ammonium sulfate. This eliminates the need for ammonium sulfate removal, which helps prevent increases in maintenance costs.

第2の態様に係る脱硝装置は、仕切板は、煙道41を幅方向の複数の混合通路70a,70b,70c,70dに区画する第1仕切板62,63,64を有する。これにより、幅方向に窒素酸化物に濃度差がある排ガスを混合通路70a,70b,70c,70dごとに窒素酸化物に濃度を均一化することができる。 The denitration device according to the second embodiment has first partition plates 62, 63, and 64 that divide the flue 41 into multiple mixing passages 70a, 70b, 70c, and 70d in the width direction. This makes it possible to equalize the nitrogen oxide concentration in exhaust gas that has a difference in nitrogen oxide concentration in the width direction for each of the mixing passages 70a, 70b, 70c, and 70d.

第3の態様に係る脱硝装置は、仕切板は、煙道41を奥行方向の複数の混合通路94a,94b,94c,94dに区画する第2仕切板91,92,93を有する。これにより、奥行方向に窒素酸化物に濃度差がある排ガスを混合通路70a,70b,70c,70dごとに窒素酸化物に濃度を均一化することができる。 The denitration device according to the third aspect has second partition plates 91, 92, and 93 that divide the flue 41 into multiple mixing passages 94a, 94b, 94c, and 94d in the depth direction. This allows exhaust gas with a difference in nitrogen oxide concentration in the depth direction to have a uniform nitrogen oxide concentration for each mixing passage 70a, 70b, 70c, and 70d.

第4の態様に係る脱硝装置は、複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dは、ガス流れ方向の長さがガス流れ方向に直交する方向の長さより長い。これにより、窒素酸化物に濃度差がある排ガスを均一に混合するために、十分な長さの流路幅または流路面積に対する流路長さを十分に確保することができる混合通路70a,70b,70c,70d,94a,94b,94c,94dを確保することができる。 In the denitration device according to the fourth aspect, the length of the multiple mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d in the gas flow direction is longer than the length in the direction perpendicular to the gas flow direction. This makes it possible to ensure that the mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d have a sufficient flow path width or a sufficient flow path length relative to the flow path area in order to uniformly mix exhaust gases having different concentrations of nitrogen oxides.

第5の態様に係る脱硝装置は、複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dが隣接する方向の混合通路70a,70b,70c,70d,94a,94b,94c,94dの長さは、流れる排ガスの窒素酸化物濃度が低い混合通路70a,70b,70c,70d,94a,94b,94c,94dに比べて、流れる排ガスの窒素酸化物濃度が高い混合通路70a,70b,70c,70d,94a,94b,94c,94dが短い。これにより、十分な長さの混合通路70a,70b,70c,70d,94a,94b,94c,94dを設けることができ、複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dを流れる排ガスを適正に混合することができる。 In the denitrification device of the fifth aspect, the lengths of the multiple mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d in the direction in which they are adjacent are shorter in the mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d through which the exhaust gas flowing has a high nitrogen oxide concentration than in the mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d through which the exhaust gas flowing has a low nitrogen oxide concentration. This allows mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, and 94d to be provided with sufficient length, and allows the exhaust gas flowing through multiple mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, and 94d to be properly mixed.

第6の態様に係る脱硝装置は、複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dにおけるガス流入部に混合促進装置81が設けられる。これにより、混合促進装置81が混合通路70a,70b,70c,70d,94a,94b,94c,94dに流入した排ガスを混合することで、混合通路70a,70b,70c,70d,94a,94b,94c,94dを流れる排ガスの混合を促進し、窒素酸化物の濃度を適正に均一化することができる。 In the denitration device according to the sixth aspect, a mixing promotion device 81 is provided at the gas inlet portion of the multiple mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, and 94d. As a result, the mixing promotion device 81 mixes the exhaust gas flowing into the mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, and 94d, promoting the mixing of the exhaust gas flowing through the mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, and 94d, and appropriately homogenizing the concentration of nitrogen oxides.

第7の態様に係る脱硝装置は、煙道41は、第3水平煙道部(水平通路)41eと第3鉛直煙道部(鉛直通路)41fとを有し、選択還元型触媒61は、第3鉛直煙道部(鉛直通路)41fに設けられ、仕切板62,63,64,91,92,93は、少なくとも第3鉛直煙道部(鉛直通路)41fに設けられる。これにより、複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dを流れる排ガスにおける窒素酸化物濃度の均一化を図ることができると共に、仕切板62,63,64,91,92,93の簡素化を図ることができる。 In the denitration device according to the seventh aspect, the flue 41 has a third horizontal flue section (horizontal passage) 41e and a third vertical flue section (vertical passage) 41f, the selective reduction catalyst 61 is provided in the third vertical flue section (vertical passage) 41f, and the partition plates 62, 63, 64, 91, 92, and 93 are provided at least in the third vertical flue section (vertical passage) 41f. This makes it possible to homogenize the nitrogen oxide concentration in the exhaust gas flowing through the multiple mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, and 94d, and to simplify the partition plates 62, 63, 64, 91, 92, and 93.

第8の態様に係る脱硝装置は、仕切板62,63,64,91,92,93は、第3水平煙道部41eと第3鉛直煙道部41fにまたがって設けられる。これにより、複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dの流路長さを長く確保することができ、複数の混合通路70a,70b,70c,70d,94a,94b,94c,94dを流れる排ガスの混合を促進することができる。 In the denitration device according to the eighth aspect, the partition plates 62, 63, 64, 91, 92, and 93 are provided across the third horizontal flue section 41e and the third vertical flue section 41f. This ensures a long flow path length for the multiple mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, and 94d, and promotes the mixing of the exhaust gases flowing through the multiple mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, and 94d.

第9の態様に係るボイラは、鉛直方向に沿って設置される火炉11と、火炉11に配置される燃焼装置12と、火炉11における燃焼ガスの流れ方向の下流側に配置される煙道41と、煙道41に配置される熱交換器としての過熱器51,52,53、再熱器54,55、節炭器56と、煙道41における熱交換器より下流側に配置される脱硝装置43,43A,43Bとを備える。これにより、脱硝装置43,43A,43Bにて、窒素酸化物濃度に応じた適量の還元剤を排ガスに供給することとなり、選択還元型触媒61は、排ガス中の窒素酸化物を効率良く還元除去することができ、性能の向上を図ることができる。そして、窒素酸化物を還元した後に残った還元剤が硫黄酸化物と反応して硫安が生成することが抑制され、硫安の除去作業などが不要となり、メンテナンスコストの増大を抑制することができると共に、石炭焚きボイラ10の稼働効率の低下を抑制することができる。 The boiler according to the ninth aspect includes a furnace 11 installed vertically, a combustion device 12 arranged in the furnace 11, a flue 41 arranged downstream of the flow direction of the combustion gas in the furnace 11, superheaters 51, 52, 53, reheaters 54, 55, and a coal economizer 56 as heat exchangers arranged in the flue 41, and denitration devices 43, 43A, and 43B arranged downstream of the heat exchangers in the flue 41. As a result, the denitration devices 43, 43A, and 43B supply an appropriate amount of reducing agent according to the nitrogen oxide concentration to the exhaust gas, and the selective reduction catalyst 61 can efficiently reduce and remove nitrogen oxides in the exhaust gas, thereby improving performance. In addition, the reducing agent remaining after reducing the nitrogen oxides is prevented from reacting with sulfur oxides to generate ammonium sulfate, making it unnecessary to perform work to remove ammonium sulfate, thereby preventing an increase in maintenance costs and preventing a decrease in the operating efficiency of the coal-fired boiler 10.

なお、上述した実施形態では、仕切板62,63,64,91,92,93(混合通路70a,70b,70c,70d,94a,94b,94c,94d)と選択還元型触媒61との間に還元剤供給装置65を設けたが、この構成に限定されるものではない。例えば、混合通路70a,70b,70c,70d,94a,94b,94c,94dにおけるガス流れ方向の下流側端部(仕切板62,63,64,91,92,93におけるガス流れ方向の下流側端部で挟まれた位置)に還元剤供給装置65を設けてもよい。また、仕切板62,63,64,91,92,93(混合通路70a,70b,70c,70d,94a,94b,94c,94d)におけるガス流れ方向の下流側端部を選択還元型触媒61の流入部まで延出し、混合通路70a,70b,70c,70d,94a,94b,94c,94dにおけるガス流れ方向の下流側端部に還元剤供給装置65を設けてもよい。 In the above embodiment, the reducing agent supply device 65 is provided between the partition plates 62, 63, 64, 91, 92, 93 (mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d) and the selective reduction catalyst 61, but this configuration is not limited to this. For example, the reducing agent supply device 65 may be provided at the downstream end of the mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d in the gas flow direction (the position sandwiched between the downstream end of the partition plates 62, 63, 64, 91, 92, 93 in the gas flow direction). In addition, the downstream end of the gas flow direction in the partition plates 62, 63, 64, 91, 92, 93 (mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d) may be extended to the inlet of the selective reduction catalyst 61, and a reducing agent supply device 65 may be provided at the downstream end of the gas flow direction in the mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d.

また、上述した実施形態にて、仕切板62,63,64,91,92,93および混合通路70a,70b,70c,70d,94a,94b,94c,94dの数は、実施形態に限定されるものではなく、火炉11や煙道41などの形状や大きさなどにより適宜設定すればよいものである。 In addition, in the above-described embodiment, the number of partition plates 62, 63, 64, 91, 92, 93 and mixing passages 70a, 70b, 70c, 70d, 94a, 94b, 94c, 94d is not limited to the embodiment, and may be set appropriately depending on the shape and size of the furnace 11, the flue 41, etc.

また、上述した第1実施形態では、第1仕切板62,63,64により混合通路70a,70b,70c,70dを設け、第3実施形態では、第2仕切板91,92,93により混合通路94a,94b,94c,94dを設けたが、第1仕切板62,63,64と第2仕切板91,92,93により格子状の混合通路を設けてもよい In addition, in the first embodiment described above, mixing passages 70a, 70b, 70c, and 70d are provided by the first partition plates 62, 63, and 64, and in the third embodiment, mixing passages 94a, 94b, 94c, and 94d are provided by the second partition plates 91, 92, and 93, but a lattice-shaped mixing passage may also be provided by the first partition plates 62, 63, and 64 and the second partition plates 91, 92, and 93 .

10 石炭焚きボイラ(ボイラ)
11 火炉
12 燃焼装置
13 燃焼ガス通路
21,22,23,24,25 燃焼バーナ
41 煙道(ガス通路)
41a 第1水平煙道部
41b 第1鉛直煙道部
41c 第2水平煙道部
41d 第2鉛直煙道部
41e 第3水平煙道部(水平通路)
41f 第3鉛直煙道部(鉛直通路)
42 エアヒータ
43,43A,43B 脱硝装置
44 ガスダクト
51,52,53 過熱器
54,55 再熱器
56 節炭器
61 選択還元型触媒(脱硝触媒)
62,63,64 第1仕切板(仕切板)
65 還元剤供給装置
66 制御装置
70a,70b,70c,70d 混合通路(領域)
71 還元剤供給ポンプ
72a,72b,72c,72d 還元剤供給管
73a,73b,73c,73d ノズル
81 混合促進装置
81a,81b,81c,81d 混合促進器
91,92,93 第2仕切板(仕切板)
94a,94b,94c,94d 混合通路(領域)
10. Coal-fired boiler (boiler)
11 Furnace 12 Combustion device 13 Combustion gas passage 21, 22, 23, 24, 25 Combustion burner 41 Flue (gas passage)
41a First horizontal flue section 41b First vertical flue section 41c Second horizontal flue section 41d Second vertical flue section 41e Third horizontal flue section (horizontal passage)
41f Third vertical flue section (vertical passage)
42 Air heater 43, 43A, 43B Denitrification device 44 Gas duct 51, 52, 53 Superheater 54, 55 Reheater 56 Economizer 61 Selective reduction catalyst (denitrification catalyst)
62, 63, 64 First partition plate (partition plate)
65 Reducing agent supply device 66 Control device 70a, 70b, 70c, 70d Mixing passage (area)
71 Reducing agent supply pump 72a, 72b, 72c, 72d Reducing agent supply pipe 73a, 73b, 73c, 73d Nozzle 81 Mixing promotion device 81a, 81b, 81c, 81d Mixing promotion device 91, 92, 93 Second partition plate (partition plate)
94a, 94b, 94c, 94d Mixing passage (area)

Claims (8)

ガス通路に設けられる選択還元型触媒と、
前記ガス通路における前記選択還元型触媒よりガス流れ方向の上流側に設けられて前記ガス通路をガス流れ方向に直交する方向の複数の領域に区画する仕切板と、
前記ガス通路における前記仕切板と前記選択還元型触媒との間に設けられて前記複数の領域を流れるガスの窒素酸化物濃度に応じた量の還元剤を供給する還元剤供給装置と、
を備え、
前記複数の領域が隣接する方向の前記領域の長さは、流れるガスの窒素酸化物濃度が低い前記領域に比べて、流れるガスの窒素酸化物濃度が高い前記領域が短い、
脱硝装置。
A selective catalytic reduction catalyst provided in the gas passage;
a partition plate provided in the gas passage upstream of the selective catalytic reduction catalyst in a gas flow direction, the partition plate dividing the gas passage into a plurality of regions in a direction perpendicular to the gas flow direction;
a reducing agent supplying device provided in the gas passage between the partition plate and the selective catalytic reduction catalyst, for supplying a reducing agent in an amount corresponding to a nitrogen oxide concentration of the gas flowing through the plurality of regions;
Equipped with
a length of the regions in a direction in which the regions are adjacent to each other is shorter in the region where the nitrogen oxide concentration of the flowing gas is high than in the region where the nitrogen oxide concentration of the flowing gas is low;
Denitrification equipment.
前記仕切板は、前記ガス通路を幅方向の複数の領域に区画する第1仕切板を有する、
請求項1に記載の脱硝装置。
The partition plate includes a first partition plate that divides the gas passage into a plurality of regions in a width direction.
The denitration device according to claim 1.
前記複数の領域は、ガス流れ方向の長さがガス流れ方向に直交する方向の長さより長い、
請求項1または請求項2に記載の脱硝装置。
The length of the plurality of regions in the gas flow direction is longer than the length in the direction perpendicular to the gas flow direction.
The denitrification device according to claim 1 or 2.
前記複数の領域におけるガス流入部に混合促進装置が設けられる、
請求項1から請求項3のいずれか一項に記載の脱硝装置。
A mixing promotion device is provided at the gas inlet portion in the plurality of regions;
The denitration device according to any one of claims 1 to 3.
前記仕切板は、前記ガス通路を奥行方向の複数の領域に区画する第2仕切板を有する、
請求項1から請求項4のいずれか一項に記載の脱硝装置。
The partition plate includes a second partition plate that divides the gas passage into a plurality of regions in a depth direction.
The denitration device according to any one of claims 1 to 4.
前記ガス通路は、水平通路と、前記水平通路におけるガス流れ方向の下流側に連続する鉛直通路とを有し、前記選択還元型触媒は、前記鉛直通路に設けられ、前記仕切板は、少なくとも前記鉛直通路に設けられる、
請求項1から請求項5のいずれか一項に記載の脱硝装置。
the gas passage includes a horizontal passage and a vertical passage continuing to a downstream side of the horizontal passage in a gas flow direction, the selective catalytic reduction catalyst is provided in the vertical passage, and the partition plate is provided at least in the vertical passage.
The denitration device according to any one of claims 1 to 5.
前記仕切板は、前記水平通路と前記鉛直通路にまたがって設けられる、
請求項6に記載の脱硝装置。
The partition plate is provided across the horizontal passage and the vertical passage.
The denitration device according to claim 6.
鉛直方向に沿って設置される火炉と、
前記火炉に配置される燃焼装置と、
前記火炉における燃焼ガスの流れ方向の下流側に配置される煙道と、
前記煙道に配置される熱交換器と、
前記煙道における前記熱交換器より下流側に配置される請求項1から請求項7のいずれか一項に記載の脱硝装置と、
を備えるボイラ。
A furnace installed along a vertical direction;
A combustion device disposed in the furnace;
A flue is disposed downstream in a flow direction of the combustion gas in the furnace;
A heat exchanger disposed in the flue;
The denitration device according to any one of claims 1 to 7, which is disposed downstream of the heat exchanger in the flue;
A boiler equipped with
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JP2014094355A (en) 2012-11-09 2014-05-22 Mitsubishi Heavy Ind Ltd Exhaust gas denitrification system, and regeneration method and catalyst replacement method in exhaust gas denitrification device
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JP2009228918A (en) 2008-03-19 2009-10-08 Hitachi Ltd Control device and control method of boiler
JP2010048537A (en) 2008-08-25 2010-03-04 Babcock Hitachi Kk Flue-gas nox removal device
JP2014094355A (en) 2012-11-09 2014-05-22 Mitsubishi Heavy Ind Ltd Exhaust gas denitrification system, and regeneration method and catalyst replacement method in exhaust gas denitrification device
CN106984191A (en) 2017-03-29 2017-07-28 华电电力科学研究院 A kind of efficient hybrid system of reducing agent ammonia and its method of work for SCR denitrating flue gas

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