JP2725797B2 - Equipment for removing nitrogen oxides from exhaust gas - Google Patents
Equipment for removing nitrogen oxides from exhaust gasInfo
- Publication number
- JP2725797B2 JP2725797B2 JP63228950A JP22895088A JP2725797B2 JP 2725797 B2 JP2725797 B2 JP 2725797B2 JP 63228950 A JP63228950 A JP 63228950A JP 22895088 A JP22895088 A JP 22895088A JP 2725797 B2 JP2725797 B2 JP 2725797B2
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- signal
- flow rate
- nitrogen oxides
- amount
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims description 70
- 239000007789 gas Substances 0.000 title claims description 42
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 36
- 239000003054 catalyst Substances 0.000 claims description 23
- 229910021529 ammonia Inorganic materials 0.000 claims description 18
- 238000002347 injection Methods 0.000 claims description 17
- 239000007924 injection Substances 0.000 claims description 17
- 238000011144 upstream manufacturing Methods 0.000 claims description 14
- 230000001105 regulatory effect Effects 0.000 description 4
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、排ガス中の窒素酸化物除去装置における還
元剤制御装置に係り、特に排ガス中の窒素酸化物量が急
増した際にも好適な窒素酸化物除去が行なえるようにな
した排ガス中の窒素酸化物除去装置における還元剤制御
装置に関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reducing agent control device in a device for removing nitrogen oxides in exhaust gas, and more particularly to a nitrogen gas suitable for use when the amount of nitrogen oxides in exhaust gas is rapidly increased. The present invention relates to a reducing agent control device in a device for removing nitrogen oxides in exhaust gas, which is capable of removing oxides.
排ガス中の窒素酸化物除去装置における還元剤として
は、一般にアンモニア（NH3）が使用されるが、従来装
置を第２図に示す。第２図において、40は窒素酸化物
（NOx）を含有する未処理排ガス、41は排ガス40の通過
する通路、１、２、３、４は煙道41内に設置された窒素
酸化物還元用触媒層であり、排ガス上流側より１、２、
３、４の各触媒層が直列に４段配置されている。５は、
これら触媒層の上流側に設置されたアンモニア注入ノズ
ル装置、７は排ガス流量検出器、８は排ガス流量信号、
９は排ガス中のNOx濃度検出器、10はNOx濃度信号、11は
乗算器、12は総NOx量信号、13はNOx量に対するアンモニ
ア量のモル比設定器、14はモル比信号、15は乗算器、16
はNH3流量設定信号、17はNH3流量検出器、18はNH3流量
検出信号、19は演算器、20は偏差信号、22はNH3流量設
定信号の変化量を算出するための微分器、29はNH3流量
先行信号、30は演算器、31はNH3流量補正信号である。N
Ox濃度や排ガス流量の変化は、総NOx量信号12の変化と
なって乗算器15に入力され、NH3流量設定信号16を変化
させ、またその値の変化速度は微分器22で算出され、NH
3流量先行信号29となり演算器30よりNH3流量補正信号31
として演算器19に送られ、演算器19からNH3流量に対す
る偏差信号20がNH3流量調整弁21に送られ、上流側NH3配
管27、上流側NH3注入ノズル５から噴射されるNH3が制御
される。Ammonia (NH 3 ) is generally used as a reducing agent in a device for removing nitrogen oxides in exhaust gas. A conventional device is shown in FIG. In FIG. 2, 40 is an untreated exhaust gas containing nitrogen oxides (NOx), 41 is a passage through which the exhaust gas 40 passes, 1, 2, 3, and 4 are for reducing nitrogen oxides installed in the flue 41. The catalyst layer, from the exhaust gas upstream side 1, 2,
Three or four catalyst layers are arranged in four stages in series. 5 is
An ammonia injection nozzle device installed upstream of these catalyst layers, 7 is an exhaust gas flow detector, 8 is an exhaust gas flow signal,
9 is a NOx concentration detector in exhaust gas, 10 is a NOx concentration signal, 11 is a multiplier, 12 is a total NOx amount signal, 13 is a molar ratio setting device of ammonia amount to NOx amount, 14 is a molar ratio signal, and 15 is a multiplier. Bowl, 16
Is the NH 3 flow rate setting signal, 17 is the NH 3 flow rate detector, 18 is the NH 3 flow rate detection signal, 19 is the calculator, 20 is the deviation signal, and 22 is the differentiator for calculating the variation of the NH 3 flow rate setting signal. , 29 is an NH 3 flow rate advance signal, 30 is a calculator, and 31 is an NH 3 flow rate correction signal. N
Change of Ox concentration and flow rate of the flue gas, as a change in the total NOx amount signal 12 is inputted to the multiplier 15, to change the NH 3 flow rate setting signal 16, also the rate of change of the value is calculated by the differentiator 22, NH
(3) Flow rate advance signal (29) and NH ( 3) flow rate correction signal (31)
Sent to the arithmetic unit 19 as a computing unit 19 deviation signal 20 for the NH 3 flow rate is sent to the NH 3 flow rate regulating valve 21 from the upstream side NH 3 pipe 27, NH 3 is injected from the upstream side NH 3 injection nozzle 5 Is controlled.
定常運転状態ではNOx濃度９と未処理ガス量９の積、
すなわち総NOx量信号12に比例したNH3ガスを注入する。
そのときの触媒層各段におけるNH3ガス濃度は、左下の
グラフの実線で示すように、最終段の４段目触媒層４の
出口でNH3ガスはほぼ零となるようにし、脱硝装置で処
理された出口排ガス中にNH3ガスが残留して２次公害を
生じないようにしている。ところが、排ガス中のNOx濃
度や未処理排ガス量が急増した場合は、NH3注入ノズル
５からの注入量をそれに見合って増加しても、点線で示
すように排ガス中のNH3濃度は、３段目触媒層３の後部
では零となり、処理すべき排ガス中に未反応のNOxが残
る。この原因の詳細については充分には解明されてない
が、増加したNH3が上流側の触媒層１、２の触媒中に、
未反応のNH3として貯えられるのではないかと考えられ
る。In a steady operation state, the product of the NOx concentration 9 and the untreated gas amount 9,
That is, NH 3 gas proportional to the total NOx amount signal 12 is injected.
As shown by the solid line in the lower left graph, the NH 3 gas concentration at each stage of the catalyst layer at that time was adjusted so that the NH 3 gas became almost zero at the outlet of the fourth stage catalyst layer 4 in the final stage. NH 3 gas does not remain in the treated exhaust gas to prevent secondary pollution. However, when the NOx concentration in the exhaust gas and the untreated exhaust gas amount increase rapidly, even if the injection amount from the NH 3 injection nozzle 5 is correspondingly increased, the NH 3 concentration in the exhaust gas becomes 3 as shown by the dotted line. At the rear of the stage catalyst layer 3, the value becomes zero, and unreacted NOx remains in the exhaust gas to be treated. Although the details of this cause are not fully understood, the increased NH 3 is contained in the catalyst of the upstream catalyst layers 1 and 2.
It is thought that it may be stored as unreacted NH 3 .
上記したように、従来装置においては排ガス量や排ガ
ス中のNOx濃度の増加による負荷の急激な増加時には、N
Ox除去率の低下と、それに伴う未反応NOxガスの外気へ
の排出という問題があった。As described above, in the conventional apparatus, when the load suddenly increases due to an increase in the exhaust gas amount or the NOx concentration in the exhaust gas, the N
There has been a problem that the Ox removal rate is reduced and the unreacted NOx gas is discharged to the outside air.
上記した従来技術の課題は、排ガス通路に触媒層を上
流側から下流側に複数段配置し、上記触媒層の上流側排
ガス中にアンモニアを注入するノズルを設けた排ガス中
の窒素酸化物除去装置において、前記複数段の触媒層の
中間段に下流側アンモニア注入ノズルを設け、負荷上昇
時には上流側アンモニア注入ノズルからのアンモニア注
入量よりも下流側アンモニア注入ノズルからのアンモニ
ア注入量を先行して増加させる調整装置を設けたことを
特徴とする排ガス中の窒素酸化物除去装置によって解決
される。The above-mentioned problem of the prior art is that an apparatus for removing nitrogen oxides in exhaust gas is provided in which a catalyst layer is arranged in a plurality of stages from an upstream side to a downstream side in an exhaust gas passage, and a nozzle for injecting ammonia into the exhaust gas on the upstream side of the catalyst layer is provided. In the above, a downstream ammonia injection nozzle is provided at an intermediate stage of the plurality of catalyst layers, and when the load increases, the ammonia injection amount from the downstream ammonia injection nozzle is increased earlier than the ammonia injection amount from the upstream ammonia injection nozzle. The problem is solved by a device for removing nitrogen oxides in exhaust gas, which is provided with an adjusting device for causing the gas to flow.
第２図に示す従来技術では、負荷の急激な増加により
３段目以降でのNH3濃度はほぼ零となるが、本発明のご
とく負荷の急激な増加によりNH3濃度がほぼ零となる少
し上流、すなわち例えば第２図の２段目触媒層２と３段
目触媒層３の間に、負荷の急激な上昇時にNH3を注入す
る下流側注入ノズル６を配置することによって、残留NH
3の不足な補えるようになり、未処理ガスの排出、脱硝
率の低下がない。In the prior art shown in FIG. 2, the NH 3 concentration in the third and subsequent stages becomes almost zero due to a sudden increase in load, but the NH 3 concentration becomes almost zero due to a sudden increase in load as in the present invention. By arranging a downstream injection nozzle 6 for injecting NH 3 when the load suddenly rises upstream, that is, for example, between the second catalyst layer 2 and the third catalyst layer 3 in FIG.
The shortage of 3 can be compensated, and there is no emission of untreated gas and no reduction in the denitration rate.
本発明の実施例を第１図により説明する。第２図に示
した従来技術との相違点は、触媒層２と３の間に下流側
アンモニア注入ノズル６を設置し、NH3配管28を接続し
ている。また、乗算器15からの出力信号であるNH3流量
設定信号16は、演算器19と微分器22に送られるようにな
っている。微分器22からはNH3流量設定値変化信号23が
出力され、換算変換器24に入り、24からNH3補充信号25
が出力され、NH3補充調整弁26を制御するようになって
いる。一方、演算器19にはNH3流量検出信号18とNH3流量
設定信号16が入力され、両信号の差が演算され、偏差信
号20が19より発信され、NH3流量調整弁21の開度を制御
する。An embodiment of the present invention will be described with reference to FIG. The difference from the prior art shown in FIG. 2 is that a downstream ammonia injection nozzle 6 is installed between the catalyst layers 2 and 3, and an NH 3 pipe 28 is connected. Further, the NH 3 flow rate setting signal 16 which is an output signal from the multiplier 15 is sent to the calculator 19 and the differentiator 22. An NH 3 flow rate set value change signal 23 is output from the differentiator 22, enters the conversion converter 24, and receives an NH 3 replenishment signal 25 from the converter 24.
Is output to control the NH 3 replenishment regulating valve 26. On the other hand, the NH 3 flow rate detection signal 18 and the NH 3 flow rate setting signal 16 are input to the calculator 19, the difference between the two signals is calculated, a deviation signal 20 is transmitted from 19, and the opening degree of the NH 3 flow rate regulating valve 21 is Control.
排ガス流量、また排ガス中のNOx濃度が上昇して脱硝
装置の負荷が上昇したときは、下流側NH3配管28のNH3補
充調整26を信号25によって制御し、下流側NH3注入ノズ
ル６へのNH3量を増加させる。これにより、触媒層各段
におけるNH3ガス濃度は、第１図左下方の点線で示すよ
うになり、２段目触媒層２と３段目触媒層３の間にノズ
ル６からNH3量が追加され、３段目触媒層以降の下流側
のNH3量が増加され、NOxと反応して４段目触媒層出口に
おいては流出する排ガス中の残留NH3量はほぼ零にな
る。なお、第２図と重複する部分については、第２図の
説明で述べたので説明を省略する。When the exhaust gas flow rate and the NOx concentration in the exhaust gas increase and the load on the denitrification device increases, the NH 3 replenishment adjustment 26 of the downstream NH 3 pipe 28 is controlled by the signal 25 to the downstream NH 3 injection nozzle 6. Increase the amount of NH 3 . As a result, the NH 3 gas concentration in each stage of the catalyst layer becomes as shown by the dotted line in the lower left of FIG. 1, and the NH 3 amount is supplied from the nozzle 6 between the second stage catalyst layer 2 and the third stage catalyst layer 3. In addition, the amount of NH 3 on the downstream side after the third-stage catalyst layer is increased, and the amount of residual NH 3 in the exhaust gas flowing out at the outlet of the fourth-stage catalyst layer after reacting with NOx becomes almost zero. 2 are described in the description of FIG. 2, and the description is omitted.
本発明によれば、負荷の急激な増加時にも、脱硝装置
内のNH3の不足を生ずることなく、未処理のNOxガスを排
出することがないので、窒素酸化物除去率の低下を防ぐ
ことができる。According to the present invention, even when a sudden increase in load, without causing the shortage of NH 3 in the denitration apparatus, since there is no possible to discharge the untreated NOx gas, to prevent a reduction in nitrogen oxide removal rate Can be.
第１図は、本発明の実施例説明図、第２図は、従来技術
の説明図である。 １、２、３、４…脱硝装置内の触媒層、５…上流側アン
モニア注入ノズル、６…下流側アンモニア注入ノズル、
７…排ガス流量検出器、９…NOx濃度検出器、11…乗算
器、12…総NOx量信号、13…モル比設定器、15…乗算
器、16…NH3流量設定信号、17…NH3流量検出器、19…演
算器、20…偏差信号、21…NH3流量調整弁、22…微分
器、23…NH3流量設定値変化信号、24…換算変換器、25
…NH3補充信号、26…NH3補充調整弁、27…上流側NH3配
管、28…下流側NH3配管、40…未処理排ガス、41…排ガ
ス通路。FIG. 1 is an explanatory view of an embodiment of the present invention, and FIG. 2 is an explanatory view of a conventional technique. 1, 2, 3, 4 ... catalyst layer in denitration apparatus, 5 ... upstream ammonia injection nozzle, 6 ... downstream ammonia injection nozzle,
7 ... exhaust gas flow rate detector, 9 ... NOx concentration sensor, 11 ... multiplier, 12 ... total NOx amount signal, 13 ... molar ratio setter, 15 ... multiplier, 16 ... NH 3 flow rate setting signal, 17 ... NH 3 Flow rate detector, 19… Calculator, 20… Deviation signal, 21… NH 3 flow rate adjustment valve, 22… Differentiator, 23… NH 3 flow rate set value change signal, 24… Conversion converter, 25
… NH 3 replenishment signal, 26… NH 3 replenishment regulating valve, 27… upstream NH 3 pipe, 28… downstream NH 3 pipe, 40… untreated exhaust gas, 41… exhaust gas passage.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭59−225726（ＪＰ，Ａ) 特開 昭53−66868（ＪＰ，Ａ) 特公 昭60−44009（ＪＰ，Ｂ２) ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-225726 (JP, A) JP-A-53-66868 (JP, A) JP-B-60-44009 (JP, B2)
Claims (1)
複数段配置し、上記触媒層の上流側排ガス中にアンモニ
アを注入するノズルを設けた排ガス中の窒素酸化物除去
装置において、前記複数段の触媒層の中間段に下流側ア
ンモニア注入ノズルを設け、負荷上昇時には上流側アン
モニア注入ノズルからのアンモニア注入量よりも下流側
アンモニア注入ノズルからのアンモニア注入量を先行し
て増加させる調整装置を設けたことを特徴とする排ガス
中の窒素酸化物除去装置。An apparatus for removing nitrogen oxides in exhaust gas, comprising a plurality of catalyst layers arranged in an exhaust gas passage from an upstream side to a downstream side and a nozzle for injecting ammonia into the exhaust gas upstream of the catalyst layer. An adjustment device that has a downstream ammonia injection nozzle provided in an intermediate stage of a plurality of catalyst layers, and increases the amount of ammonia injected from the downstream ammonia injection nozzle earlier than the amount of ammonia injected from the upstream ammonia injection nozzle when the load increases. An apparatus for removing nitrogen oxides in exhaust gas, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63228950A JP2725797B2 (en) | 1988-09-13 | 1988-09-13 | Equipment for removing nitrogen oxides from exhaust gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63228950A JP2725797B2 (en) | 1988-09-13 | 1988-09-13 | Equipment for removing nitrogen oxides from exhaust gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0275325A JPH0275325A (en) | 1990-03-15 |
| JP2725797B2 true JP2725797B2 (en) | 1998-03-11 |
Family
ID=16884399
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63228950A Expired - Fee Related JP2725797B2 (en) | 1988-09-13 | 1988-09-13 | Equipment for removing nitrogen oxides from exhaust gas |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2725797B2 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59225726A (en) * | 1983-06-07 | 1984-12-18 | Babcock Hitachi Kk | Ammonia catalytic reductive denitration apparatus |
-
1988
- 1988-09-13 JP JP63228950A patent/JP2725797B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0275325A (en) | 1990-03-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |