JP3565607B2

JP3565607B2 - Method and apparatus for controlling amount of ammonia injection into denitration device

Info

Publication number: JP3565607B2
Application number: JP04463195A
Authority: JP
Inventors: 肇古林
Original assignee: Babcock Hitachi KK
Current assignee: Mitsubishi Power Ltd
Priority date: 1995-03-03
Filing date: 1995-03-03
Publication date: 2004-09-15
Anticipated expiration: 2019-09-15
Also published as: JPH08238416A

Description

【０００１】
【産業上の利用分野】
本発明は、脱硝装置へのアンモニア注入量制御方法および装置に係り、特に燃焼排ガス中の窒素酸化物を低減する脱硝装置へのアンモニア注入量制御方法および装置であって、燃焼装置の負荷変化時にも応答遅れの少ない脱硝装置へのアンモニア注入量制御方法および装置に関する。
【０００２】
【従来の技術】
排ガス中の窒素酸化物を除去する脱硝装置の系統を図４により、また脱硝装置へのアンモニア注入量制御についての従来の技術を図３に基づき説明する。
ガスタービン、燃焼装置等の排ガスを排出する装置から排出された排ガスは煙道１を通り脱硝触媒を内蔵した脱硝反応器２にてアンモニアガスと接触反応して排ガス中の窒素酸化物（以下ＮＯ_Ｘという）を除去された後、煙突３へと導かれる。一方、アンモニアガスはアンモニアガス母管４に設けられたアンモニアガス流量調節弁５で流量調節され、脱硝反応器２の上流に設けられたノズル６より注入される。
【０００３】
図３において、前記脱硝反応器２に注入する排ガスの流量信号７に脱硝反応器入口に設けられた入口ＮＯ_Ｘ濃度分析計８からの生ＮＯ_Ｘ濃度信号２５を乗算し、排ガス中のＮＯ_Ｘ総量を算出する。一方、入口ＮＯ_Ｘ濃度分析計８からのＮＯ_Ｘ濃度を排ガスの基準酸素含有率（通常は６％）時に換算したＯ_２換算後のＮＯ_Ｘ信号２６と脱硝反応器出口ＮＯｘ濃度設定信号発生器９の出力信号を演算器１０にて下記の（１）式の演算を行ない、出口ＮＯｘ濃度設定信号発生器９で設定した出口ＮＯｘ濃度値にするために必要な脱硝率を求め、これに相当する先行モル比信号１１ａに関数発生器１１で信号変換する。
【０００４】
【数１】

【０００５】
一方、脱硝反応器出口に設けられた出口ＮＯｘ濃度分析計１２からのＯ_２換算後のＮＯ_Ｘ濃度信号１２ａと脱硝反応器出口ＮＯｘ濃度設定値を減算器１３で比較し、偏差を比例積分器１４で比例積分動作させた後の信号１４ａ（モル比補正信号）で、加算器１５にて先に求めた先行モル比信号１１ａを修正し、修正モル比信号１５ａを求め、乗算器１６でＮＯ_Ｘ総量信号と乗算して要求アンモニア流量信号１６ａを求め、アンモニア流量発信器１７による実測アンモニア流量信号と減算器１８で比較し、偏差を比例積分器１９で比例積分動作し、アンモニアガス流量調節弁５でアンモニア注入量を制御する。
【０００６】
【発明が解決しようとする課題】
上記従来技術では、要求アンモニア流量信号を演算するために脱硝反応器入口に設けられたＮＯ_Ｘ分析計の信号を使用している。しかしながら、ＮＯ_Ｘ分析計はその測定原理上、分析計自身の応答遅れが約１分、排ガスサンプリング系統の遅れが約２分あり、合計で約３分程度の応答遅れがある。
【０００７】
したがって、燃焼装置などの排ガスを排出する装置の負荷変化等で反応器入口ＮＯ_Ｘ濃度が変化しても、変化時のＮＯ_Ｘ分析計からのＮＯ_Ｘ信号出力は約３分後に検出されることとなり、必要なアンモニアガス流量の注入も必要な注入タイミングからその時間だけ遅れる問題があった。
本発明の目的は、上記従来技術の問題点を解決し、ＮＯ_Ｘ分析計の応答遅れを補ない、必要なタイミングにて適切な量のアンモニアガスを注入することができる脱硝装置へのアンモニア注入量制御方法および装置を提供することにある。
【０００８】
【課題を解決するための手段】
上記目的を達成するため本願で特許請求する発明は以下のとおりである。
（１）排ガスを排出する装置からの被処理排ガス流量と脱硝装置入口ＮＯｘ濃度により入口総ＮＯｘ量を求め、出口ＮＯｘ濃度設定値と入口ＮＯｘ濃度により排ガスに対するアンモニアの先行モル比信号を求め、出口ＮＯｘ濃度設定値と検出値の偏差に基づいてモル比補正信号を求め、前記総ＮＯｘ量、先行モル比信号、モル比補正信号に基づき脱硝装置へのアンモニア注入量を制御する方法において、燃焼装置の負荷変化時には、排ガスを排出する装置の負荷量に基づいて仮りの入口ＮＯｘ濃度を算出し、この算出値を入口ＮＯｘ濃度検出値で補正し、補正後の入口ＮＯｘ濃度を使って前記入口総ＮＯｘ量および先行モル比信号を求めることを特徴とする燃焼装置の負荷変化時における脱硝装置へのアンモニア注入量制御方法。
（２）燃焼装置からの被処理排ガス流量と該排ガスの脱硝装置入口ＮＯｘ濃度とから入口総ＮＯｘ量を算出する手段と、脱硝装置の出口ＮＯｘ濃度設定値と入口ＮＯｘ濃度とに基づき排ガスに対する先行モル比信号を演算する手段と、出口ＮＯｘ濃度設定値と検出値の偏差に基づきモル比補正信号を算出する手段と、前記先行モル比信号とモル比補正信号と前記総ＮＯｘ量とから要求アンモニア流量信号を算出する手段と、この要求アンモニア流量信号とアンモニア流量検出値に基づきアンモニア流量調節弁を制御する手段とを備えた脱硝装置へのアンモニア注入量制御装置において、燃焼装置の負荷変化時には該負荷量に基づき仮りの入口ＮＯｘ濃度を算出し、この算出値を入口ＮＯｘ濃度検出値で補正して前記入口ＮＯｘ濃度とする手段と、燃焼装置の負荷安定時には入口ＮＯｘ濃度検出器からの検出値を前記入口ＮＯｘ濃度とするように切換える手段と、これら手段により得られた入口ＮＯｘ濃度に基づき先行モル比信号および入口総ＮＯｘ量を算出する手段とを設けたことを特徴とする脱硝装置へのアンモニア注入量制御装置。
【０００９】
【作用】
ガスタービン燃料流量信号のような燃焼装置の負荷信号から作成する脱硝反応器の模擬の入口ＮＯ_Ｘ濃度信号は、実機の運転結果に基づいて各負荷における脱硝装置入口ＮＯ_Ｘ濃度をあらかじめプログラム化して各負荷に応じて直ちに算出するようにしておくことにより、ＮＯ_Ｘ濃度分析計から求めるＮＯ_Ｘ濃度信号のように遅れの要素はない。しかし、プログラム値は固定のため、その時のガスタービン等の燃焼状態の違い等により微妙にＮＯ_Ｘ濃度が変化した場合、プログラム値と多少ずれる欠点がある。一方、ＮＯ_Ｘ分析計からのＮＯ_Ｘ濃度は前述した応答遅れはあるものの、計器誤差は分析計フルスケールの±１％程度以内であり正確なＮＯ_Ｘ値を検出可能である。
【００１０】
したがって、遅れのないプログラムＮＯ_Ｘ濃度信号値と遅れはあるが正確なＮＯ_Ｘ分析計からのＮＯ_Ｘ濃度信号値の差分をプログラム化して各負荷に応じて算出したＮＯ_Ｘ信号に加算すれば、実際のＮＯ_Ｘ濃度に近い信号を作成することができる。
【００１１】
【実施例】
本発明の実施例を図１により説明する。
燃料流量指令装置２０からの信号を受け関数発生器２４で脱硝反応器入口生ＮＯ_Ｘ濃度の仮信号２４ａをプログラムにより設定し、脱硝反応器入口ＮＯ_Ｘ濃度計８からの生ＮＯ_Ｘ濃度信号２５との偏差を減算器２１で求める。そしてこの偏差と前記したプログラム生ＮＯ_Ｘ濃度信号を加算器２３で加算し、最終的な入口生ＮＯ_Ｘ濃度信号とする。
【００１２】
また燃料流量指令器２０からの信号を受け、関数発生器２７で脱硝反応器入口Ｏ_２換算ＮＯ_Ｘ濃度仮信号２７ａをプログラムにより設定し、この信号を前記した生ＮＯ_Ｘ信号２５と同一の手法で減算器２１、加算器２３、Ｏ_２換算入口ＮＯ_Ｘ濃度信号２６を用いて最終的なＯ_２換算入口ＮＯ_Ｘ濃度信号を作成する。
なお、燃焼装置の負荷変化中は切替リレー２２をＸ２側に切替えて前記したようにプログラムＮＯ_Ｘ濃度信号と、入口ＮＯ_Ｘ濃度分析計８からの入口ＮＯ_Ｘ濃度信号を用いて最終的な入口ＮＯ_Ｘ濃度信号を作成するが、負荷が変化していない時は切替リレー２２をＸ１側に切替え、入口ＮＯ_Ｘ濃度分析計８からの生ＮＯ_Ｘ濃度信号２５、換算ＮＯ_Ｘ信号２６がそのまま最終的なそれぞれのＮＯ_Ｘ濃度信号となるようにする。
【００１３】
これは負荷変化していない時は脱硝反応器入口ＮＯ_Ｘ濃度の変化はほとんどなく、入口ＮＯ_Ｘ濃度分析計の応答遅れも制御上問題とはならないからである。そのため精度の高いＮＯ_Ｘ分析計からのＮＯ_Ｘ信号をそのまま使用するものである。
上記した実施例は、負荷変化時のＮＯ_Ｘ濃度の変化幅および変化率の大きいガスタービン用脱硝装置を主体にして記載したものであるが、ボイラ用脱硝装置においても負荷変化時のＮＯ_Ｘ分析計の応答遅れによるアンモニアガスの注入遅れは同じであり、これらについても同様の効果を得ることができる。
【００１４】
本実施例の効果について図２により説明する。負荷立上り時はＮＯ_Ｘ濃度分析計からのＮＯ_Ｘ濃度信号２８は約３分程度の応答遅れがあるが、プログラムＮＯ_Ｘ濃度信号２９は遅れがないため実際のＮＯ_Ｘ濃度値に近い値となる。
またプログラムＮＯ_Ｘ濃度信号２９では実際のＮＯ_Ｘ挙動に見られるオーバーシュート、アンダーシュート量のプログラムまでは設定困難であるが、プログラムＮＯ_Ｘ濃度信号２９に本信号と分析計からのＮＯ_Ｘ濃度信号２８の差分を加えた最終ＮＯ_Ｘ濃度信号３０はそれが可能となる。またガスタービンの場合、燃料流量指令（負荷）とＮＯ_Ｘ濃度の関係はリニアではなく、負荷上昇の過程でバーナ切替えがあり負荷上昇中に入口ＮＯ_Ｘ濃度がいったん大きく低下し、その後急上昇するが、このような急激なＮＯ_Ｘ挙動をＮＯ_Ｘ分析計だけで検出することは不可能であるが、燃料流量指令とバーナ切替えのタイミングは一定の関係がある。したがって、この燃料流量指令によりプログラムしたプログラムＮＯ_Ｘ濃度信号であればこのような急激なＮＯ_Ｘ濃度変化があっても遅れの要素なく、実際のＮＯ_Ｘ値に近い値を模擬することが可能となる。
【００１５】
【発明の効果】
本発明によれば、精度は高いが応答遅れがある分析計からのＮＯ_Ｘ信号と応答遅れはないが固定値であるため実際のＮＯ_Ｘ挙動とは多少のずれが生じるプログラムＮＯｘ濃度信号の両方の信号のメリットを取り入れることが可能となり、燃焼装置の負荷変化に即応して適切なアンモニア注入が実施でき、脱硝装置の性能を高く維持することができる。
【図面の簡単な説明】
【図１】
本発明の実施例を示すアンモニア注入量制御系統図。
【図２】実施例の効果を示す図。
【図３】従来技術になるアンモニア注入量制御系統図。
【図４】ガスタービン用脱硝装置の系統図。
【符号の説明】
１…煙道、２…脱硝反応器、３…煙突、４…アンモニアガス母管、５…アンモニアガス流量調節弁、６…ノズル、７…排ガス流量信号、８…入口ＮＯ_Ｘ濃度分析計、９…出口ＮＯｘ濃度設定信号発生器、１０…演算器、１１…関数発生器、１１ａ…先行モル比信号、１２…出口ＮＯｘ濃度分析計、１３…減算器、１４…比例積分器、１４ａ…モル比補正信号、１５…加算器、１５ａ…修正モル比信号、１６…乗算器、１６ａ…要求アンモニア流量信号、１７…アンモニア流量発信器、１７ａ…実測アンモニア流量信号、１８…減算器、１９…比例積分器、２０…燃料流量指令装置、２１…減算器、２２…切替リレー、２３…加算器、２４…関数発生器、２４ａ…入口生ＮＯ_Ｘ濃度仮信号、２５…入口生ＮＯ_Ｘ濃度信号、２６…Ｏ_２換算入口ＮＯ_Ｘ濃度信号、２７…関数発生器、２８…分析計からのＮＯ_Ｘ濃度信号、２９…プログラムＮＯ_Ｘ濃度信号、３０…最終ＮＯ_Ｘ濃度信号。[0001]
[Industrial applications]
The present invention relates to a method and a device for controlling the amount of ammonia injected into a denitration device, and more particularly to a method and a device for controlling the amount of ammonia injected to a denitration device for reducing nitrogen oxides in combustion exhaust gas. The present invention also relates to a method and an apparatus for controlling the amount of ammonia injected into a denitration apparatus having a small response delay.
[0002]
[Prior art]
A system of a denitration apparatus for removing nitrogen oxides in exhaust gas will be described with reference to FIG. 4 and a conventional technique for controlling the amount of ammonia injected into the denitration apparatus will be described with reference to FIG.
Exhaust gas discharged from a gas exhaust device such as a gas turbine or a combustion device passes through a flue 1 and comes into contact with and reacts with ammonia gas in a denitration reactor 2 having a built-in denitration catalyst to cause nitrogen oxide (hereinafter referred to as NO) in the exhaust gas. _X ) is led to the chimney 3. On the other hand, the flow rate of ammonia gas is controlled by an ammonia gas flow control valve 5 provided in the ammonia gas mother pipe 4, and is injected from a nozzle 6 provided upstream of the denitration reactor 2.
[0003]
3, by multiplying the raw NO _X concentration signal 25 from the inlet NO _X concentration analyzer 8, wherein provided in the flow rate signal 7 of the exhaust gas to be injected into the denitrification reactor 2 in the denitration reactor inlet, NO _X in the exhaust gas Calculate the total amount. On the other hand, a NO _X signal 26 converted into O _{2 by} converting the NO _X concentration from the inlet NO _X concentration analyzer 8 into a reference oxygen content (usually 6%) of the exhaust gas and a NO x concentration setting signal generator at the outlet of the denitration reactor The output signal of No. 9 is calculated by an arithmetic unit 10 according to the following equation (1), and the denitration rate required to obtain the outlet NOx concentration value set by the outlet NOx concentration setting signal generator 9 is obtained. The signal is converted by the function generator 11 into the preceding molar ratio signal 11a.
[0004]
(Equation 1)

[0005]
On the other hand, the NO _X concentration signal 12a and the denitration reactor outlet NOx concentration setting of O ₂ after conversion from the outlet NOx concentration analyzer 12 provided in the denitration reactor outlet compared by the subtracter 13, the deviation proportional integrator The adder 15 corrects the preceding molar ratio signal 11a previously obtained by the signal 14a (molar ratio correction signal) after performing the proportional integration operation in 14, obtains the corrected molar ratio signal 15a, _The required ammonia flow signal 16a is obtained by multiplying by the _X total amount signal, and the measured ammonia flow signal by the ammonia flow transmitter 17 is compared with the subtractor 18; the deviation is proportionally integrated by the proportional integrator 19; 5 controls the amount of injected ammonia.
[0006]
[Problems to be solved by the invention]
The above prior art, using the NO _X analyzer signal in the denitrification reactor inlet in order to calculate the required ammonia flow rate signal. However, NO _X analyzer on the measurement principle, the analyzer itself response delay of about 1 minute, there delay of exhaust gas sampling system is about 2 minutes, there is a response delay of the order of about 3 minutes in total.
[0007]
Accordingly, even after changing the reactor inlet NO _X concentration at a load change or the like of a device for discharging the exhaust gas, such as combustion equipment, NO _X signal output from the NO _X analyzer during changes to be detected after about 3 minutes Thus, there has been a problem that the injection of the required ammonia gas flow rate is delayed by the time from the required injection timing.
An object of the present invention shows the above-mentioned solution to the problems of the prior art, no complement the response delay of the NO _X analyzer, ammonia injection into a denitration apparatus that can inject an appropriate amount of ammonia gas at a necessary timing It is an object of the present invention to provide a quantity control method and apparatus.
[0008]
[Means for Solving the Problems]
The invention claimed in this application to achieve the above object is as follows.
(1) The total NOx amount at the inlet is obtained from the flow rate of the exhaust gas to be treated from the exhaust gas discharge device and the NOx concentration at the denitration apparatus, and the preceding molar ratio signal of ammonia to the exhaust gas is obtained from the outlet NOx concentration set value and the inlet NOx concentration. A method for determining a molar ratio correction signal based on a difference between a NOx concentration set value and a detected value, and controlling an amount of ammonia injected into a denitration device based on the total NOx amount, a preceding molar ratio signal, and a molar ratio correction signal, comprising: When the load changes, a temporary inlet NOx concentration is calculated based on the load of the exhaust gas discharging device, the calculated value is corrected by the detected inlet NOx concentration, and the corrected inlet NOx concentration is used by using the corrected inlet NOx concentration. A method of controlling the amount of ammonia injected into a denitration apparatus when a load of a combustion device changes, wherein a NOx amount and a preceding molar ratio signal are obtained.
(2) Means for calculating the total NOx amount at the inlet from the flow rate of the exhaust gas to be treated from the combustion device and the NOx concentration at the denitration device inlet of the exhaust gas; A means for calculating a molar ratio signal; a means for calculating a molar ratio correction signal based on a deviation between the set value of the outlet NOx concentration and the detected value; and a method for calculating the required ammonia from the preceding molar ratio signal, the molar ratio correction signal, and the total NOx amount. A control apparatus for controlling the amount of ammonia injected into a denitration apparatus, comprising: a means for calculating a flow rate signal; and means for controlling an ammonia flow rate control valve based on the required ammonia flow rate signal and the detected ammonia flow rate. A means for calculating a temporary inlet NOx concentration based on the load amount and correcting the calculated value with the detected inlet NOx concentration to obtain the inlet NOx concentration; Means for switching the detected value from the inlet NOx concentration detector to the inlet NOx concentration when the load of the combustion device is stabilized; and, based on the inlet NOx concentration obtained by these means, the leading mole ratio signal and the inlet total NOx amount are changed. A device for controlling the amount of ammonia injected into a denitration device, comprising: means for calculating.
[0009]
[Action]
Inlet NO _X density signals simulated denitration reactor made from the load signal of a combustion device, such as a gas turbine fuel flow signal is pre-programmed the denitrator inlet NO _X concentration at each load based on actual operating results By calculating immediately according to each load, there is no delay element unlike the NO _X concentration signal obtained from the NO _X concentration analyzer. However, the programmed value for the fixed, if subtly NO _X concentration by a difference or the like of the combustion state of the gas turbine or the like at that time has changed, there is some shift drawbacks as programmed value. On the other hand, although the NO _X concentration from the NO _X analyzer has the above-mentioned response delay, the instrument error is within ± 1% of the full scale of the analyzer, and an accurate NO _X value can be detected.
[0010]
Therefore, if there is a program NO _X density signal value and the delayed without delay but by adding to the NO _X signal calculated in accordance with each load by programmed differential of the NO _X density signal value from the exact NO _X analyzer, A signal close to the actual NO _X concentration can be created.
[0011]
【Example】
An embodiment of the present invention will be described with reference to FIG.
A function generator 24 receives a signal from the fuel flow rate command device 20, sets a temporary signal 24a of the raw NO _X concentration at the denitration reactor inlet by a program, and generates a raw NO _X concentration signal 25 from the NO _X concentration meter 8 at the denitration reactor. Is calculated by the subtractor 21. Then, the difference and the above-mentioned program raw NO _X concentration signal are added by the adder 23 to obtain a final entrance raw NO _X concentration signal.
[0012]
The receiving signals from the fuel flow rate command unit 20, the denitration reactor inlet O ₂ in terms NO _X concentration tentative signal 27a is set by the program with the function generator 27, the same procedure and raw NO _X signal 25 the signal mentioned above Then, a final O ₂ converted inlet NO _X concentration signal is created using the subtracter 21, the adder 23, and the O ₂ converted inlet NO _X concentration signal 26.
Note that the final inlet during a load change in the combustion device using a program NO _X density signals as described above by switching the switching relay 22 in the X2 side, the inlet NO _X concentration signal from the inlet NO _X concentration analyzer 8 The NO _X concentration signal is created, but when the load is not changed, the switching relay 22 is switched to the X1 side, and the raw NO _X concentration signal 25 and the converted NO _X signal 26 from the inlet NO _X concentration analyzer 8 are finally output. The respective NO _X concentration signals are set to be appropriate.
[0013]
This is hardly a change in the denitrification reactor inlet NO _X concentration when not in load changes, the response delay of the inlet NO _X concentration analyzer also because not a control problem. Therefore, the NO _X signal from the highly accurate NO _X analyzer is used as it is.
Embodiment described above, but are those described by the load changes when the concentration of NO _X variation and change rate larger gas turbine denitration apparatus mainly, also NO _X analysis during a load change in the denitration unit boiler The delay in injection of ammonia gas due to the response delay of the meter is the same, and the same effect can be obtained in these cases.
[0014]
The effect of this embodiment will be described with reference to FIG. When the load rises, the NO _X concentration signal 28 from the NO _X concentration analyzer has a response delay of about 3 minutes, but the program NO _X concentration signal 29 has no delay and therefore has a value close to the actual NO _X concentration value. .
The overshoot seen in the program NO _X in concentration signal 29 actually of the NO _X behavior, but until the undershoot amount of program is difficult settings, NO _X concentration signal from the signal and spectrometer program NO _X concentration signal 29 the final NO _X concentration signal 30 which the difference plus 28 becomes possible therewith. In the case of a gas turbine, the fuel flow command (load) and the relationship of the NO _X concentration is not linear, the inlet NO _X concentration during load increase has switched burner in the process of load increase is reduced temporarily increased, but then rapidly increased Although it is impossible to detect such a rapid NO _X behavior only with the NO _X analyzer, the fuel flow rate command and the timing of burner switching have a certain relationship. Therefore, if the program NO _X concentration signal programmed by the fuel flow rate command such without elements of delay even if abrupt NO _X concentration change, it is possible to simulate a close to the actual of the NO _X value value and Become.
[0015]
【The invention's effect】
According to the present invention, both the accuracy is high NO _X signal delayed response although not programmed NOx concentration signal is some deviation occurs between the actual of the NO _X behavior for a fixed value from the analyzer with a response delay , The appropriate ammonia injection can be performed in response to a change in the load of the combustion device, and the performance of the denitration device can be maintained at a high level.
[Brief description of the drawings]
FIG.
FIG. 2 is a diagram showing an ammonia injection amount control system according to an embodiment of the present invention.
FIG. 2 is a diagram showing the effect of the embodiment.
FIG. 3 is a diagram of an ammonia injection amount control system according to the related art.
FIG. 4 is a system diagram of a denitration device for a gas turbine.
[Explanation of symbols]
1 ... flue, 2 ... denitration reactor, 3 ... chimney, 4 ... ammonia gas main pipe, 5 ... ammonia gas flow rate control valve, 6 ... nozzle, 7 ... exhaust gas flow rate signal, 8 ... inlet NO _X concentration analyzer, 9 ... Outlet NOx concentration setting signal generator, 10 ... Calculator, 11 ... Function generator, 11a ... Preceding mole ratio signal, 12 ... Outlet NOx concentration analyzer, 13 ... Subtractor, 14 ... Proportional integrator, 14a ... Molar ratio Correction signal, 15: Adder, 15a: Modified molar ratio signal, 16: Multiplier, 16a: Required ammonia flow signal, 17: Ammonia flow transmitter, 17a: Actual measured ammonia flow signal, 18: Subtractor, 19: Proportional integration , 20 ... fuel flow command device, 21 ... subtractor, 22 ... switching relay, 23 ... adder, 24 ... function generator, 24a ... inlet raw NO _X concentration temporary signal, 25 ... inlet raw NO _X concentration signal, 26 ... _{O 2} in terms of the inlet NO _X concentration signal, 27: function generator, 28: NO _X concentration signal from analyzer, 29: program NO _X concentration signal, 30: final NO _X concentration signal.

Claims

The total NOx amount at the inlet is obtained from the flow rate of the exhaust gas to be processed from the exhaust gas discharge device and the NOx concentration at the denitration apparatus, and the preceding molar ratio signal of ammonia to the exhaust gas is obtained from the set NOx concentration value at the outlet and the NOx concentration at the inlet. A method for determining a molar ratio correction signal based on a deviation between the measured value and the detected value, and controlling an amount of ammonia injected into the denitration device based on the total NOx amount, the preceding molar ratio signal, and the molar ratio correction signal. In some cases, a provisional inlet NOx concentration is calculated based on the load of the exhaust gas discharge device, the calculated value is corrected with the detected inlet NOx concentration, and the corrected inlet NOx concentration is used to correct the inlet total NOx amount and A method for controlling the amount of ammonia injected into a denitration device when a load of a combustion device changes , wherein a preceding mole ratio signal is obtained.

Prior for the exhaust gas on the basis of means for calculating the inlet total amount of NO _X from the denitrator inlet concentration of NO _X to be treated exhaust gas flow rate and exhaust gas, and an outlet NOx concentration setting and the inlet concentration of NO _X denitration apparatus from the combustion device request from the means for calculating the molar ratio signal, means for calculating the molar ratio correction signal based on the deviation of the outlet NOx concentration set value and the detected value, the preceding molar ratio signal and the molar ratio correction signal and the total amount of NO _X In a device for controlling the amount of ammonia injected into a denitration apparatus comprising means for calculating an ammonia flow signal and means for controlling an ammonia flow control valve based on the required ammonia flow signal and the detected ammonia flow value, when the load of the combustion device changes, Means for calculating a provisional inlet NO _X concentration based on the load amount, correcting the calculated value with the detected inlet NO _X concentration to obtain the inlet NO _X concentration; And means for switching to said inlet NO _X concentration detected value from the load in a stable state inlet NO _X concentration detector of combustion apparatus, prior molar ratio signal and inlet total based on the inlet NO _X concentration obtained by these means A device for controlling the amount of ammonia injected into a denitration device, comprising: means for calculating a NO _X amount.