JP3701526B2

JP3701526B2 - Method and apparatus for controlling flue gas desulfurization apparatus

Info

Publication number: JP3701526B2
Application number: JP30246499A
Authority: JP
Inventors: 剛大川
Original assignee: Babcock Hitachi KK
Current assignee: Mitsubishi Power Ltd
Priority date: 1999-10-25
Filing date: 1999-10-25
Publication date: 2005-09-28
Anticipated expiration: 2019-10-25
Also published as: JP2001120947A

Description

【０００１】
【発明の属する技術分野】
本発明は、ボイラ等の排ガス中に含まれる硫黄酸化物を低減する排煙脱硫装置に係わり、特に消泡剤設備を有する排煙脱硫装置と方法に関する。
【０００２】
【従来の技術】
排煙脱硫装置の概略系統図を図３に示す。ボイラ等から排出する排ガスは煙道に導かれて排煙脱硫装置の吸収塔３１内に入る。一方吸収塔３１内では吸収塔循環ポンプ３２から供給された石灰石等の吸収剤を含んだ吸収液がスプレノズル３３から噴霧され、前記排ガスと気液接触して、吸収液に排ガス中に含まれている硫黄酸化物が吸収されて、浄化された排ガスは煙突から排出される。
【０００３】
吸収塔３１には排ガス中に含まれている硫黄酸化物を吸収するのに必要な石灰石等のカルシウム化合物をスラリ化した吸収液が供給される。この吸収塔３１内の吸収液は石灰石の供給量により、吸収液ｐＨが制御されるが、吸収液は排ガス中の硫黄酸化物を吸収し、生成した亜硫酸カルシウムを酸化させて石膏とするために酸化空気ブロワにより酸化用空気が吸収液中に供給される。
【０００４】
吸収塔３１の下部又は別個に設けられた吸収液貯溜部３４には、硫黄酸化物を除去し、生成された石膏と吸収剤を含む吸収液が蓄えられている。また、吸収液貯溜部３４から排出した石膏を含む吸収液は吸収塔ブリードポンプ３５により石膏回収系３６を経由して一部は吸収塔３１に、他の部分は脱硫排水３８として排水処理系３７に送られる。
【０００５】
吸収液貯溜部３４に存在する石膏と吸収剤を含む吸収液を吸収塔循環ポンプ３２により循環し、吸収塔３１との気液接触により硫黄酸化物を除去するが、排ガス性状または吸収塔３１に供給される吸収剤中の不純成分（Ｍｇ等）により吸収液貯溜部３４に蓄えられている吸収液内には、泡が発生して異常上昇を起こすことがある。このため、前記吸収液貯溜部３４には消泡剤が消泡剤供給ポンプ２９により供給されている。
【０００６】
以上のような系統において、吸収塔３１に供給されている消泡剤は脱硫装置の吸収塔３１へ流入する排ガス条件（排ガス流量およびＳＯ_２濃度）の変化により制御される。図４に消泡剤供給量制御系統図を示す。すなわち、排ガス流量信号３と入口ＳＯ_２濃度信号２２を乗算器２３で掛け算して総ＳＯ_２量２４を算出し、これに基づき関数発生器２５により消泡剤供給量設定値２６を得て、これと実際の消泡剤供給量信号１２との偏差を比例積分を行う調節計２８で調節して消泡剤供給ポンプ２９を作動させる。
【０００７】
【発明が解決しようとする課題】
上記従来技術では、排ガスのガス性状（ＨＣｌ濃度など）の検出、吸収剤である石灰石の性状が把握できないことから吸収塔の吸収液貯溜部に蓄えられている保有液が異常上昇しない条件においても消泡剤を供給する必要があるとともに、消泡剤を過剰投入すると脱硫性能が低下するという問題があった。
【０００８】
本発明の課題は、吸収塔の吸収液貯溜部に蓄えられている吸収液の性状を算出することにより、最適な消泡剤の供給量を支援し、安定した排ガスの脱硫性能を得るとともに、脱硫装置の薬品消費量の低減を図ることである。
【０００９】
【課題を解決するための手段】
本発明の上記課題は、連続計測できない状態量（ガス性状、液性状）を計測しているプロセス量から推定し、これらの情報から消泡剤添加の支援を行うことにより達成できる。
【００１０】
すなわち、本発明は次の二つの発明からなる。
（１）ボイラ等の燃焼装置からの排ガスを導入する吸収塔と、該吸収塔内で脱硫剤であるカルシウム化合物のスラリを含む吸収液を排ガスと接触させて排ガス中の硫黄酸化物を吸収させ、排ガス中の硫黄酸化物を吸収した吸収液を溜める吸収液貯溜部と、該吸収液貯溜部に溜まった吸収液を吸収塔内に導き、再び排ガスと接触させる吸収液循環供給手段と、吸収液に消泡剤を添加する消泡剤添加手段とを備えた排煙脱硫装置において、燃焼装置で用いられる燃料量、燃焼装置から吸収塔に導入される排ガス流量、該排ガス中のＨＣｌ濃度、吸収液貯溜部内の吸収液液量、石灰石スラリ中のマグネシウム濃度、吸収液貯溜部から抜き出される吸収液溜部抜出流量、吸収塔内に供給される石灰石スラリ流量、吸収液貯溜部から石膏回収用脱水機への吸収液供給量、石膏回収用脱水機からの脱硫排水流量、及び吸収液への消泡剤供給量から吸収液貯溜部での液組成を計算する手段と、前記液組成計算手段から算出した排ガス中の硫黄酸化物を吸収した吸収液中のＣｌ濃度、Ｍｇ濃度および消泡剤濃度を算出する手段と、前記消泡剤濃度算出手段の算出結果に基づき吸収液への最適な消泡剤供給量を供給消泡剤添加手段により供給させる制御装置とを設けた排煙脱硫装置。
【００１１】
（２）ボイラ等の燃焼装置からの排ガスを吸収塔に導入し、該吸収塔内で脱硫剤である石灰石スラリを含む吸収液を排ガスと接触させて排ガス中の硫黄酸化物を吸収させて吸収液貯溜部に溜めて、吸収液貯溜部には消泡剤を添加し、該吸収液貯溜部の吸収液を吸収塔内に導き、再び排ガスと接触させる排煙脱硫方法において、
燃焼装置で用いられる燃料量、燃焼装置から吸収塔に導入される排ガス流量、該排ガス中のＨＣｌ濃度、吸収液貯溜部内の吸収液液量、石灰石スラリ中のマグネシウム濃度、吸収液貯溜部から抜き出される吸収液溜部抜出流量、吸収塔内に供給される石灰石スラリ流量、吸収液貯溜部から石膏回収用脱水機への吸収液供給量、石膏回収用脱水機からの脱硫排水流量、吸収液への消泡剤供給量から吸収液貯溜部での液組成を計算し、前記液組成の計算結果から算出した排ガス中の硫黄酸化物を吸収した吸収液中のＣｌ濃度、Ｍｇ濃度および消泡剤濃度を算出し、吸収液への消泡剤供給量を制御する排煙脱硫方法。
【００１２】
前記消泡剤の添加量を制御する方法には、消泡剤供給手段の起動停止も含まれる。
【００１３】
【作用】
本発明においては、脱硫装置に流入する排ガス性状および吸収液の性状により消泡剤の最適量を出力するとともに、消泡剤の要否により消泡剤供給ポンプを起動停止させる信号を出力する。それによって、吸収塔に蓄えられている吸収液の異常上昇を防止できるだけでなく、薬品消費量の低減が可能であるとともに過剰投入による脱硫性能の低下防止を図れる。
【００１４】
【発明の実施の形態】
本発明の実施の形態の排煙脱硫装置の消泡剤演算装置の制御系統図を図１に示し、この制御系統図は図３に示す排煙脱硫装置に適用されるものであり、ボイラ燃料量信号１と燃料性状信号２と排ガス流量信号３を排ガス性状演算器４により次の式（１）に従いＨＣｌ濃度５を算出する。ここでＨＣｌ濃度を選択する理由は、排ガス中のＨＣｌ濃度上昇により、脱硫装置内でのＣｌ⁻濃度が上昇し、これに従い、吸収液の泡が形成されやすくなるからである。
【００１５】

ここで、２２．４は理想気体の標準体積（リットル）、３５．５は塩素の分子量である。
【００１６】
排ガス流量信号３とブリードポンプ３５により吸収液貯溜部３４から抜出され、石膏回収系３６内にある石膏回収用脱水機に供給される吸収液の脱水機供給流量信号９と吸収塔レベル信号７と吸収剤スラリ流量信号８と予め測定された石灰石不純物中のＭｇ濃度割合信号１０と脱硫排水流量信号１１と消泡剤供給量信号１２と排ガス性状演算器４により算出した排ガス中のＨＣｌ濃度５を液性状演算器１３に入力し、液性状演算器１３で演算された脱硫装置内のＣｌ⁻濃度１４とＭｇ^２＋濃度１５と消泡剤濃度１６をそれぞれ式（２）、（３）、（４）に従って算出する。
【００１７】

【００１８】

【００１９】

ここで、ｔは演算周期である。
【００２０】
この算出した脱硫装置内のＣｌ⁻濃度１４とＭｇ^２＋濃度１５と消泡剤濃度１６と排ガス中のＨＣｌ濃度５と消泡剤供給流量信号１２から消泡剤演算装置１７により消泡剤の必要の要否の判断及び必要量の演算をするとともに、消泡剤供給量演算結果１８または消泡剤供給ポンプ起動指令１９、停止指令２０を制御装置２１に出力する。これにより、吸収塔に保有している吸収液の異常上昇が防止でき、薬品消費量の低減が図れるとともに過剰投入による脱硫性能の低下を防止することができる。
【００２１】
ここで脱硫装置内のＣｌ⁻濃度とＭｇ^２＋濃度を測定する理由は、脱硫装置の吸収液中のＣｌ⁻とＭｇ^２＋の濃度が上昇すると、泡が形成され、吸収液が異常上昇するためである。そのためＣｌ⁻とＭｇ^２＋の濃度は、脱硫装置内で抑えることができないため、消泡剤を投入して形成された泡を消す必要がある。
【００２２】
図２に本発明の実施の形態に係わる消泡剤供給量制御系統図を示す。
排ガス流量信号３と吸収塔入口ＳＯ_２濃度信号２２が乗算器２３で乗算され、得られた総ＳＯ_２量信号２４に基づき関数発生器２５で消泡剤供給量設定値信号２６を得る。この消泡剤供給量設定値に前記消泡剤供給量演算装置１７で得られた消泡剤供給量演算結果１８を加算器２７で加算し、得られた値と実際の消泡剤供給量との偏差を調節計２８で算出し、この偏差に基づき、比例積分により調整後の消泡剤供給量を決めて消泡剤供給ポンプ２９を作動させる。
【００２３】
こうして、脱硫装置内の液性状を計算し、消泡剤の過剰投入を防止でき、薬品消費量の低減が図れるとともに過剰投入による脱硫性能の低下を防止することができる。
【００２４】
上記した例では吸収塔に排ガスを導入し、スプレノズルなどで吸収液を排ガス中に噴霧する装置についての例を示したが、本発明の方法は排ガスの流れ方向や排ガスと吸収液の接触方式（濡れ壁式吸収装置等）に関係なくいずれの場合にも有効である。
【００２５】
【発明の効果】
本発明によれば、ボイラ燃料の変化および吸収剤である石灰石の性状変化に関係なく最適な消泡剤を供給できるので安定した脱硫装置の運転ができるだけでなく、薬品消費量の低減の効果がある。
【図面の簡単な説明】
【図１】本発明の実施の形態に係わる制御系統図である。
【図２】本発明の実施の形態に係わる消泡剤供給量制御系統図である。
【図３】本発明の実施の形態に係わる排煙脱硫装置の概略系統図である。
【図４】従来技術における消泡剤供給量制御系統図である。
【符号の説明】
１ボイラ燃料量信号２燃料性状信号
３排ガス流量信号４排ガス性状演算器
５ＨＣｌ濃度７吸収塔レベル信号
８吸収剤スラリ流量信号９脱水機供給流量信号
１０石灰石不純物中のＭｇ濃度割合信号１１脱硫排水流量信号
１２消泡剤供給量信号１３液性状演算器
１４脱硫装置内のＣｌ⁻濃度
１５脱硫装置内のＭｇ^２＋濃度１６消泡剤濃度
１７消泡剤演算装置
１８消泡剤供給量演算結果
１９消泡剤供給ポンプ起動指令
２０消泡剤供給ポンプ供給停止指令
２１制御装置
２２吸収塔入口ＳＯ_２濃度信号２３乗算器
２４総ＳＯ_２量信号２５関数発生器
２６消泡剤供給量設定値信号２７加算器
２８調節計２９消泡剤供給ポンプ
３１吸収塔３２吸収塔循環ポンプ
３３スプレノズル３４吸収液貯溜部
３５吸収塔ブリードポンプ３６石膏回収系
３７排水処理系３８脱硫排水[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flue gas desulfurization apparatus that reduces sulfur oxides contained in exhaust gas such as a boiler, and more particularly to a flue gas desulfurization apparatus and method having a defoaming agent facility.
[0002]
[Prior art]
A schematic system diagram of the flue gas desulfurization apparatus is shown in FIG. The exhaust gas discharged from the boiler or the like is guided to the flue and enters the absorption tower 31 of the flue gas desulfurization apparatus. On the other hand, in the absorption tower 31, an absorption liquid containing an absorbent such as limestone supplied from the absorption tower circulation pump 32 is sprayed from the spray nozzle 33, comes into gas-liquid contact with the exhaust gas, and is contained in the exhaust gas in the absorption liquid. The exhaust gas purified by absorbing the sulfur oxide is discharged from the chimney.
[0003]
The absorption tower 31 is supplied with an absorbent obtained by slurrying a calcium compound such as limestone necessary for absorbing sulfur oxides contained in the exhaust gas. The absorption liquid in the absorption tower 31 is controlled in pH by the supply amount of limestone, but the absorption liquid absorbs sulfur oxides in the exhaust gas and oxidizes the generated calcium sulfite to form gypsum. Oxidizing air is supplied into the absorbing solution by the oxidizing air blower.
[0004]
In the absorption liquid storage section 34 provided below or separately from the absorption tower 31, an absorption liquid containing the gypsum and absorbent generated by removing sulfur oxides is stored. Further, the absorption liquid containing gypsum discharged from the absorption liquid storage section 34 is partly supplied to the absorption tower 31 via the gypsum recovery system 36 by the absorption tower bleed pump 35, and the other part is the waste water treatment system 37 as desulfurization waste water 38. Sent to.
[0005]
The absorption liquid containing gypsum and the absorbent present in the absorption liquid storage section 34 is circulated by the absorption tower circulation pump 32 and sulfur oxide is removed by gas-liquid contact with the absorption tower 31. Bubbles may be generated in the absorbent stored in the absorbent reservoir 34 due to impure components (Mg, etc.) in the supplied absorbent, causing abnormal rise. For this reason, an antifoaming agent is supplied to the absorption liquid reservoir 34 by an antifoaming agent supply pump 29.
[0006]
In the system as described above, the antifoaming agent supplied to the absorption tower 31 is controlled by changes in exhaust gas conditions (exhaust gas flow rate and SO ₂ concentration) flowing into the absorption tower 31 of the desulfurization apparatus. FIG. 4 shows a defoamer supply amount control system diagram. That is, the exhaust gas flow rate signal 3 and the inlet SO ₂ concentration signal 22 are multiplied by a multiplier 23 to calculate a total SO ₂ amount 24. Based on this, an antifoaming agent supply amount setting value 26 is obtained by a function generator 25, The defoamer supply pump 29 is operated by adjusting the deviation between this and the actual defoamer supply signal 12 by a controller 28 that performs proportional integration.
[0007]
[Problems to be solved by the invention]
In the above prior art, since the gas properties (HCl concentration, etc.) of the exhaust gas cannot be detected and the properties of the limestone as the absorbent cannot be grasped, even in the condition that the retained liquid stored in the absorption liquid storage part of the absorption tower does not rise abnormally In addition to supplying an antifoaming agent, there was a problem that desulfurization performance deteriorated when the antifoaming agent was excessively added.
[0008]
The object of the present invention is to calculate the properties of the absorption liquid stored in the absorption liquid storage part of the absorption tower, thereby supporting the optimum amount of defoaming agent and obtaining a stable desulfurization performance of exhaust gas, This is to reduce the chemical consumption of the desulfurization equipment.
[0009]
[Means for Solving the Problems]
The above-mentioned problem of the present invention can be achieved by estimating the amount of state (gas property, liquid property) that cannot be continuously measured and assisting the addition of an antifoaming agent from these information.
[0010]
That is, the present invention comprises the following two inventions.
(1) An absorption tower for introducing exhaust gas from a combustion apparatus such as a boiler, and an absorption liquid containing a slurry of a calcium compound as a desulfurizing agent in the absorption tower are brought into contact with the exhaust gas to absorb sulfur oxide in the exhaust gas. An absorption liquid storage part for storing an absorption liquid that has absorbed sulfur oxide in the exhaust gas, an absorption liquid circulation supply means for introducing the absorption liquid stored in the absorption liquid storage part into the absorption tower, and bringing it into contact with the exhaust gas again; In a flue gas desulfurization apparatus equipped with a defoaming agent adding means for adding a defoaming agent to the liquid, the amount of fuel used in the combustion apparatus, the exhaust gas flow rate introduced into the absorption tower from the combustion apparatus, the HCl concentration in the exhaust gas, Absorption liquid volume in the absorption liquid reservoir, magnesium concentration in the limestone slurry, extraction liquid extraction flow rate extracted from the absorption liquid storage area, limestone slurry flow rate supplied into the absorption tower, gypsum from the absorption liquid storage area To collection dehydrator A means for calculating the liquid composition in the absorbent storage part from the amount of the absorbent supplied, the desulfurization drainage flow rate from the dehydrator for gypsum recovery, and the amount of defoamer supplied to the absorbent, and the exhaust gas calculated from the liquid composition calculator Means for calculating Cl concentration, Mg concentration and antifoaming agent concentration in the absorbing liquid that has absorbed sulfur oxide therein, and optimal defoaming agent supply to the absorbing liquid based on the calculation result of the antifoaming agent concentration calculating means A flue gas desulfurization apparatus provided with a control device for supplying the amount by a supply defoamer adding means.
[0011]
(2) An exhaust gas from a combustion apparatus such as a boiler is introduced into an absorption tower, and an absorption liquid containing a limestone slurry as a desulfurizing agent is brought into contact with the exhaust gas in the absorption tower to absorb and absorb sulfur oxide in the exhaust gas. In the exhaust gas desulfurization method in which the defoaming agent is added to the liquid storage part, the antifoaming agent is added to the liquid storage part, the absorption liquid in the absorption liquid storage part is guided into the absorption tower, and is again brought into contact with the exhaust gas.
The amount of fuel used in the combustion device, the exhaust gas flow rate introduced into the absorption tower from the combustion device, the HCl concentration in the exhaust gas, the amount of liquid absorption in the absorption liquid storage part, the magnesium concentration in the limestone slurry, and extracted from the absorption liquid storage part Extraction flow rate of absorption liquid reservoir, flow rate of limestone slurry supplied to absorption tower, supply amount of absorption liquid from absorption liquid storage unit to gypsum recovery dehydrator, desulfurization drainage flow rate from gypsum recovery dehydrator, absorption The liquid composition in the absorbing liquid reservoir is calculated from the defoaming agent supply amount to the liquid, and the Cl concentration, Mg concentration and quenching in the absorbing liquid absorbing the sulfur oxide in the exhaust gas calculated from the calculation result of the liquid composition are calculated. A flue gas desulfurization method that calculates the concentration of foaming agent and controls the amount of antifoaming agent supplied to the absorbent.
[0012]
The method of controlling the addition amount of the antifoaming agent includes starting and stopping of the antifoaming agent supply means.
[0013]
[Action]
In the present invention, the optimum amount of the antifoaming agent is output according to the properties of the exhaust gas flowing into the desulfurization apparatus and the properties of the absorbing solution, and a signal for starting and stopping the antifoaming agent supply pump is output depending on the necessity of the antifoaming agent. Thereby, not only the abnormal increase of the absorption liquid which is stored in the absorption tower can be prevented, thereby lowering prevention of desulfurization performance due to over-on as well as a possible reduction in chemical consumption.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a control system diagram of the defoaming agent computing device of the flue gas desulfurization apparatus according to the embodiment of the present invention. This control system diagram is applied to the flue gas desulfurization apparatus shown in FIG. The HCl signal 5 is calculated from the quantity signal 1, the fuel property signal 2 and the exhaust gas flow rate signal 3 by the exhaust gas property calculator 4 according to the following equation (1). The reason for selecting the HCl concentration is that the Cl ⁻ concentration in the desulfurization apparatus increases due to the increase in the HCl concentration in the exhaust gas, and bubbles of the absorbing liquid are easily formed accordingly.
[0015]

Here, 22.4 is the standard volume (liter) of ideal gas, and 35.5 is the molecular weight of chlorine.
[0016]
The dehydrator supply flow rate signal 9 and the absorption tower level signal 7 of the absorption liquid extracted from the absorption liquid reservoir 34 by the exhaust gas flow rate signal 3 and the bleed pump 35 and supplied to the gypsum recovery dehydrator in the gypsum recovery system 36. , An absorbent slurry flow rate signal 8, a pre-measured Mg concentration ratio signal 10 in limestone impurities, a desulfurization drainage flow rate signal 11, an antifoam supply amount signal 12, and an exhaust gas property calculator 4 to calculate an HCl concentration 5 in exhaust gas. Is input to the liquid property calculator 13, and the Cl ⁻ concentration 14, Mg ²⁺ concentration 15 and defoamer concentration 16 in the desulfurization apparatus calculated by the liquid property calculator 13 are expressed by the equations (2), (3), ( Calculate according to 4).
[0017]

[0018]

[0019]

Here, t is a calculation cycle.
[0020]
From the calculated Cl ⁻ concentration 14, Mg ²⁺ concentration 15, defoamer concentration 16, HCl concentration 5 in the exhaust gas, and defoamer supply flow rate signal 12, the defoamer computing device 17 needs the defoamer. as well as the calculation of the necessity of determination and the required amount of outputs antifoaming agent supply amount calculation result 18 or antifoaming agent supply pump start command 19, the stop command 20 to the control device 21. This can prevent an abnormal increase in the absorption liquid held in the absorption tower, reduce the chemical consumption, and prevent the desulfurization performance from being lowered due to excessive input.
[0021]
Here, the reason for measuring the Cl ⁻ concentration and the Mg ²⁺ concentration in the desulfurization apparatus is that when the concentration of Cl ⁻ and Mg ²⁺ in the absorption liquid of the desulfurization apparatus increases, bubbles are formed and the absorption liquid rises abnormally. is there. Therefore, since the concentration of Cl ⁻ and Mg ²⁺ cannot be suppressed in the desulfurization apparatus, it is necessary to eliminate the foam formed by introducing an antifoaming agent.
[0022]
FIG. 2 shows a defoamer supply amount control system diagram according to the embodiment of the present invention.
The exhaust gas flow rate signal 3 and the absorption tower inlet SO ₂ concentration signal 22 are multiplied by a multiplier 23, and a defoamer supply amount set value signal 26 is obtained by a function generator 25 based on the obtained total SO ₂ amount signal 24. The defoamer supply amount calculation result 18 obtained by the defoamer supply amount calculation device 17 is added to the defoamer supply amount set value by an adder 27, and the obtained value and the actual defoamer supply amount are added. Based on this deviation, the defoamer supply pump 29 is operated by determining the adjusted defoamer supply amount by proportional integration.
[0023]
In this way, the liquid property in the desulfurization apparatus can be calculated to prevent excessive injection of the antifoaming agent, and the chemical consumption can be reduced, and the deterioration of the desulfurization performance due to excessive injection can be prevented.
[0024]
In the above example, an example of an apparatus for introducing exhaust gas into an absorption tower and spraying the absorption liquid into the exhaust gas with a spray nozzle or the like has been shown. However, the method of the present invention is based on the flow direction of the exhaust gas and the contact method between the exhaust gas and the absorption liquid ( Regardless of the wet wall type absorption device etc.), it is effective in any case.
[0025]
【The invention's effect】
According to the present invention, the optimum defoaming agent can be supplied regardless of the change in boiler fuel and the change in the properties of limestone as an absorbent, so that not only stable desulfurization operation can be performed, but also the effect of reducing chemical consumption. is there.
[Brief description of the drawings]
FIG. 1 is a control system diagram according to an embodiment of the present invention.
FIG. 2 is a defoamer supply amount control system diagram according to the embodiment of the present invention.
FIG. 3 is a schematic system diagram of the flue gas desulfurization apparatus according to the embodiment of the present invention.
FIG. 4 is a defoamer supply amount control system diagram in the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Boiler fuel amount signal 2 Fuel property signal 3 Exhaust gas flow signal 4 Exhaust gas property calculator 5 HCl concentration 7 Absorber tower level signal 8 Absorbent slurry flow signal 9 Dehydrator supply flow signal 10 Mg concentration ratio signal in limestone impurities 11 Desulfurization drainage Flow rate signal 12 Defoamer supply amount signal 13 Liquid property calculator 14 Cl ^- concentration 15 in desulfurizer 15 Mg ²⁺ concentration in desulfurizer 16 Defoamer concentration 17 Defoamer calculator 18 Defoamer supply amount calculation result 19 Defoamer supply pump start command 20 Defoamer supply pump supply stop command 21 Controller 22 Absorption tower inlet SO ₂ concentration signal 23 Multiplier 24 Total SO ₂ amount signal 25 Function generator 26 Defoamer supply amount set value signal 27 Adder 28 Controller 29 Antifoam supply pump 31 Absorption tower 32 Absorption tower circulation pump 33 Spray nozzle 34 Absorbing liquid reservoir 35 Absorption tower bleed pump 36 gypsum recovery system 37 waste water treatment system 38 desulfurization effluent

Claims

An absorption tower for introducing exhaust gas from a combustion apparatus such as a boiler, and an absorption liquid containing a slurry of a calcium compound as a desulfurizing agent in the absorption tower is brought into contact with the exhaust gas to absorb sulfur oxides in the exhaust gas. An absorption liquid storage part for storing the absorption liquid that has absorbed the sulfur oxide, an absorption liquid circulation supply means for introducing the absorption liquid stored in the absorption liquid storage part into the absorption tower and making contact with the exhaust gas again, and an absorption liquid. In a flue gas desulfurization apparatus equipped with a defoaming agent adding means for adding a foaming agent,
The amount of fuel used in the combustion device, the exhaust gas flow rate introduced into the absorption tower from the combustion device, the HCl concentration in the exhaust gas, the amount of liquid absorption in the absorption liquid storage part, the magnesium concentration in the limestone slurry, and extracted from the absorption liquid storage part The flow rate of the absorption liquid reservoir extracted, the flow rate of limestone slurry supplied into the absorption tower, the amount of liquid supply from the absorption liquid storage unit to the gypsum recovery dehydrator, the desulfurization drainage flow rate from the gypsum recovery dehydrator, and Means for calculating the liquid composition in the absorbing liquid reservoir from the defoamer supply amount to the absorbing liquid, and the Cl concentration and the Mg concentration in the absorbing liquid that have absorbed the sulfur oxide in the exhaust gas calculated from the liquid composition calculating means. And a controller for calculating the defoamer concentration, and a controller for supplying the optimum defoamer supply amount to the absorbent by the supply defoamer addition unit based on the calculation result of the defoamer concentration calculator. Flue gas desulfurization characterized by Location.

Exhaust gas from a combustion apparatus such as a boiler is introduced into an absorption tower, and an absorption liquid containing a limestone slurry as a desulfurizing agent is contacted with the exhaust gas in the absorption tower to absorb sulfur oxide in the exhaust gas, thereby absorbing liquid storage In the flue gas desulfurization method, an antifoaming agent is added to the absorption liquid storage part, the absorption liquid in the absorption liquid storage part is guided into the absorption tower, and is again brought into contact with the exhaust gas.
The amount of fuel used in the combustion device, the exhaust gas flow rate introduced into the absorption tower from the combustion device, the HCl concentration in the exhaust gas, the amount of liquid absorption in the absorption liquid storage part, the magnesium concentration in the limestone slurry, and extracted from the absorption liquid storage part Extraction flow rate of absorption liquid reservoir, flow rate of limestone slurry supplied to absorption tower, supply amount of absorption liquid from absorption liquid storage unit to gypsum recovery dehydrator, desulfurization drainage flow rate from gypsum recovery dehydrator, absorption The liquid composition in the absorbing liquid reservoir is calculated from the defoaming agent supply amount to the liquid, and the Cl concentration, Mg concentration and quenching in the absorbing liquid absorbing the sulfur oxide in the exhaust gas calculated from the calculation result of the liquid composition are calculated. A flue gas desulfurization method characterized by calculating a foaming agent concentration and controlling a defoaming agent supply amount to an absorbing liquid.