JP3655014B2 - Boiler feed pipe corrosion prevention film forming device - Google Patents

Boiler feed pipe corrosion prevention film forming device Download PDF

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Publication number
JP3655014B2
JP3655014B2 JP19458196A JP19458196A JP3655014B2 JP 3655014 B2 JP3655014 B2 JP 3655014B2 JP 19458196 A JP19458196 A JP 19458196A JP 19458196 A JP19458196 A JP 19458196A JP 3655014 B2 JP3655014 B2 JP 3655014B2
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boiler
oxygen gas
feed pipe
boiler water
flow rate
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JPH1038211A (en
Inventor
明良 林
淳 河内
則典 松田
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Energy Support Corp
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Energy Support Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
    • F16L58/02—Protection of pipes or pipe fittings against corrosion or incrustation by means of internal or external coatings
    • F16L58/04—Coatings characterised by the materials used
    • F16L58/08—Coatings characterised by the materials used by metal

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば汽力発電プラントにおいて、ボイラへボイラ水を供給するボイラ給水管の内面に酸化鉄の腐食防止皮膜を形成するボイラ給水管の腐食防止皮膜形成装置に関するものである。
【０００２】
【従来の技術】
従来、ボイラ給水管の腐食防止皮膜形成装置を構成するボイラ給水管の途中には、酸素ガス供給管を介して酸素ボンベが接続されている。酸素ガス供給管の途中にはコントロールバルブが設けられ、このコントロールバルブの開度に対応して酸素ボンベからボイラ給水管内に酸素ガスが圧送される。この酸素ガスがボイラ水給水管内に圧送されることにより、ボイラ給水管内面に酸化鉄の腐食防止皮膜が形成される。
【０００３】
前記コントロールバルブはコントローラにより駆動制御される。コントローラはボイラ給水管を流動するボイラ水の流量に基づき基準となる開度量を所定条件に基づき算出する。そして、その算出された基準となる開度量が所望の補正値に基づいて補正され、最終的な目標開度量となる。コントローラは算出した目標開度量となるようにコントロールバルブを駆動制御する。前記目標開度量を算出する際に使用される補正値は、酸素ガス供給管を流動する酸素ガスの流量（ボイラ給水管内に注入される酸素ガス量）及びボイラ水中の溶存酸素濃度に基づいて算出される。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記腐食防止皮膜形成装置においては、次のような問題があった。
【０００５】
ボイラ給水管内の圧力変動により、ボイラ給水管内の圧力が高くなった際には、その圧力が抵抗となって酸素ガスが注入しにくくなる。この場合、酸素ガスの流量が低下することから、コントローラはコントロールバルブの開度量を大きくして、酸素ガスの注入量を増加させる。
【０００６】
例えば、図３（ｂ）のグラフに示すように、ボイラ水の流量が１８００ｍ3 ／ｈで、溶存酸素濃度が０．１ｐｐｍあったとする（同図のα範囲）。この場合、所定の計算式により規定酸素注入量は２．１リットル／ｍｉｎとなる。従って、コントローラは酸素ガスの注入量が２．１リットル／ｍｉｎとなるようにコントロールバルブを駆動制御する。
【０００７】
また、次のルーチンで検出されたボイラ水の流量が、前回ルーチンと同じ流量の１８００ｍ3 ／ｈであったとする。そして、ボイラ給水管内の圧力変動により、前回制御時（前回ルーチン）よりもボイラ給水管内の圧力が３ｋｇ／ｃｍ2 上昇したとする（同図のβ範囲）。このとき、コントローラはボイラ給水管内に圧力変動が発生しても、ボイラ水の流量が変化しないことからコントロールバルブの基準となる開度量を前回ルーチン時と同開度量に保持する。前記ボイラ給水管内の圧力の上昇に伴い、ボイラ給水管内への酸素ガスの注入量が減少する。
【０００８】
すなわち、ボイラ給水管内の圧力が上昇するにつれ、同ボイラ給水管内に酸素ガスが注入されにくくなる。従って、酸素ガス流量及び溶存酸素濃度の値もそれに伴い減少することから、コントローラはボイラ水中の溶存酸素濃度が所定濃度となるようにコントロールバルブの開度量を増大させる。また、ボイラ給水管内の圧力が下降するにつれ、同ボイラ給水管内に酸素ガスが注入されやすくなる。従って、酸素ガス流量及び溶存酸素濃度の値もそれに伴い増加することから、コントローラはボイラ水中の溶存酸素濃度が所定濃度となるようにコントロールバルブの開度量を減少させる（同図のγ範囲）。
【０００９】
しかし、溶存酸素濃度及び酸素ガスの流量に基づき、基準となる開度量を補正するのでは最適な酸素ガス注入量を決定するまでに長い時間ｔ１，ｔ２を必要とする。すなわち、コントローラは酸素ガスの流量と溶存酸素濃度との値に基づいてコントロールバルブの開度量を補正していることから、ボイラ給水管の圧力が変化してもボイラ水の流量が変化しない場合や、大幅にボイラ給水管の圧力が変化した場合には、コントローラは規定酸素注入量の酸素をボイラ給水管内に注入するまで長時間要していた。
【００１０】
この場合、ボイラ水内の溶存酸素濃度に長時間ばらつきが生じることから、ボイラ給水管及びボイラに悪影響を与えるとともに、効率良くボイラ給水管内面に酸化防止被膜を形成することができないという問題があった。
【００１１】
本発明は、上記問題を解消するためになされたものであって、その目的は、ボイラ水の流量、圧力が変化しても素早く溶存酸素濃度を規定溶存酸素濃度にすることが可能なボイラ給水管の腐食防止皮膜形成装置を提供することにある。
【００１２】
【課題を解決するための手段】
上記目的を達成するために、請求項１に記載の発明では、ボイラへボイラ水を供給するボイラ給水管に酸素ガス供給手段から酸素ガスを注入し、当該ボイラ給水管内面に酸化鉄の腐食防止皮膜を形成する腐食防止皮膜形成装置において、前記酸素ガス供給手段からボイラ給水管内に注入される一定圧力に保持された酸素ガスの量を調整するための酸素ガス流量調整弁と、前記ボイラ給水管内を流動するボイラ水の流量に基づき、前記酸素ガス流量調整弁の基準となる開度量を決定する基準開度量決定手段と、前記基準開度量決定手段により決定された基準開度量を、ボイラ給水管内の圧力とボイラ水中に溶存する酸素の濃度とに基づき、前記酸素ガス流量調整弁の最適開度量に補正する補正手段と、前記補正手段により補正された最適開度量となるように、前記酸素ガス流量調整弁を駆動制御する制御手段とを備えたことをその要旨とする。
【００１３】
（作用）
従って、請求項１に記載の発明においては、まず、ボイラ給水管内を流動するボイラ水の流量に基づき、基準開度量決定手段により基準開度量が決定される。次に、補正手段により前記基準開度量が最適開度量に補正される。そして、補正された最適開度量となるように、制御手段により酸素ガス流量調整弁が駆動制御される。
【００１４】
【発明の実施の形態】
以下、本発明を具体化した一実施形態を図面に基づいて説明する。
図１に示すように、ポンプ１１とボイラ１２との間はボイラ給水管１３により連結されている。ポンプ１１の駆動に伴い、ボイラ給水管１３からボイラ１２へボイラ水が供給される。ボイラ給水管１３には、同ボイラ給水管１３を流動するボイラ水の流量を計測するためのボイラ水流量計１４が接続されている。また、ボイラ給水管１３には同ボイラ給水管１３内の圧力を測定するための圧力計１５が接続されている。
【００１５】
また、ボイラ給水管１３にはボイラ水に溶存する酸素の濃度を測定するための濃度計１６が接続されている。前記圧力計１５と濃度計１６との間におけるボイラ給水管１３の部位には、酸素供給管１７を介して酸素ボンベ１８が接続されている。なお、酸素ボンベ１８の圧力は変化せず、一定に保持される。酸素供給管１７には酸素ガス流量調整弁としてのコントロールバルブ１９が接続されている。また、コントロールバルブ１９よりも上流側における酸素供給管１７の部位には、酸素供給管１７を流動する酸素の流量を測定する酸素流量計２０が接続されている。さらに、酸素供給管１７のボイラ給水管１３への接続部位には、ボイラ水の逆流を防止する開閉弁２１と逆止弁２２が設けられている。
【００１６】
次に本実施の形態における電気的構成について説明する。
基準開度量決定手段、補正手段、制御手段としてのコントローラＣには、前記ボイラ水流量計１４、酸素流量計２０、圧力計１５、濃度計１６、コントロールバルブ１９、開閉弁２１が接続されている。コントローラＣは各計器から個々に測定信号を入力し、その測定結果に基づきコントロールバルブ１９の開度量を決定する。
【００１７】
次に、コントローラＣが実行する制御内容を図２のフローチャートに従って説明する。
ステップ１０１においては、ボイラ水流量計１４から測定値（ボイラ給水管１３を流動するボイラ水の流量）を入力する。次のステップ１０２においては、入力したボイラ水の流量からコントロールバルブ１９の基準開度量を算出する。ステップ１０３に前記ステップ１０２にて算出した基準開度量となるようにコントロールバルブ１９を開放駆動する。続くステップ１０４においては、開閉弁２１を開放し、ボイラ給水管１３内に酸素を供給する。
【００１８】
次のステップ１０５においては、酸素流量計２０及び濃度計１６からそれぞれ測定値（酸素供給管１７を流動する酸素ガスの流量、ボイラ水に溶存する溶存酸素濃度）を入力する。次のステップ１０６においては、入力した測定値に基づき、コントロールバルブ１９の開度量を補正するための第１の補正値を算出する。次のステップ１０７においては、圧力計１５から測定値（ボイラ給水管１３内の圧力）を入力する。
【００１９】
ステップ１０８においては、前回のルーチンで測定された圧力値と今回のルーチンで測定された圧力値との差を算出する。ステップ１０９においては、算出した圧力差に基づき、コントロールバルブ１９の開度量を補正するための第２の補正値を算出する。ステップ１１０においては算出した２つの補正値に基づき、前記ステップ１０２において算出した基準開度量を補正する。ステップ１１１においては、補正した開度量を目標開度量とし、その目標開度量となるようにコントロールバルブ１９を駆動制御する。そして、再度ステップ１０１に戻って以降の処理を繰り返す。
【００２０】
次に、本実施の形態における作用について説明する。
ボイラ給水管１３をボイラ水が流動すると、当該ボイラ給水管１３を流動するボイラ水の流量に基づき、コントロールバルブ１９及び開閉弁２１が所定量開放される。これにより、酸素ボンベ１８から酸素供給管１７を介してボイラ給水管１３に酸素ガスが供給される。ボイラ給水管１３に供給された酸素ガスはボイラ水に溶解される。そして、酸素ガスを溶存するボイラ水中の酸素濃度値及び酸素供給管１７を流動する酸素流量値に基づき、コントロールバルブ１９の目標開度量を決定するために使用される第１の補正値が算出される。
【００２１】
また、これと同時にボイラ給水管１３内の圧力変動に基づき、コントロールバルブ１９の目標開度量を決定するために使用される第２の補正値が算出される。この両補正値に基づきコントロールバルブ１９の開度量が適正値に補正される。
【００２２】
従って、例えば、ボイラ水の流量が１８００ｍ3 ／ｈで、ボイラ水中の溶存酸素濃度が０．１ｐｐｍある場合、所定の計算式により注入量は２．１リットル／ｍｉｎとなる。コントローラＣは酸素ガスの注入量が２．１リットル／ｍｉｎとなるようにコントロールバルブ１９を駆動制御する。そして、次のルーチンで検出されたボイラ水の流量が、前回ルーチンと同じ流量の１８００ｍ3 ／ｈであったとする。一方、ボイラ給水管１３内の圧力は前回ルーチンよりも３ｋｇ／ｃｍ2 高い６ｋｇ／ｃｍ2 であるとする。
【００２３】
本実施の形態では、ボイラ水の流量が変化していないにもかかわらず、ボイラ給水管１３内の圧力が３ｋｇ／ｃｍ2 上昇していることを圧力計１５からの検出値にてコントローラＣが検知し、コントロールバルブ１９の開度量に補正を加え、前回ルーチンよりも開度量を増大させる。これにより、ボイラ給水管１３の圧力が高く、酸素ガスがボイラ給水管１３内に注入されにくい状態となっても、コントロールバルブ１９の開度量が増大されることから、素早くボイラ給水管１３に規定量の酸素を供給することができる。
【００２４】
以上詳述したように、本実施の形態では、ボイラ給水管１３を流動するボイラ水の流量に基づき決定される基準開度量を補正するためのデータとして、ボイラ水中の溶存酸素濃度、酸素ガスの流量、ボイラ給水管１３内の圧力を使用した。これにより、ボイラ給水管１３の圧力が高く、酸素ガスがボイラ給水管１３内に注入されにくい状態となっても、コントロールバルブ１９の開度量が増大されることから、素早くボイラ給水管１３に規定量の酸素を供給することができる。
【００２５】
その結果、図３（ａ）のグラフに示すように、ボイラ給水管１３内の圧力の増減を補正要因に加えることにより、ボイラ給水管１３内に注入される酸素ガスの注入量を素速く規定量に補正でき、短時間ｔ１’（＜ｔ１）、ｔ２’（＜ｔ２）にて、その対応が図られる。これにより、ボイラ水内の溶存酸素濃度にばらつきが生じるのを防止でき、ひいては効率良くボイラ給水管１３内面に腐食防止皮膜を形成することができるとともに、ボイラ１２に与える悪影響を減少できる。
【００２６】
また、前回ルーチンで計測されたボイラ給水管１３内の圧力値と、今回ルーチンで計測されたボイラ給水管１３内の圧力値との圧力差に基づき、基準開度量を補正更新できるようにした。これにより、ボイラ給水管１３内の圧力変動を考慮した酸素ガス注入量が的確に判断され、ボイラ水中の溶存酸素濃度の変動に対し、素早く安定化できる。
【００２７】
なお、本発明は次のように実施してもよい。
（１）上記実施形態では、制御手段としてのコントローラＣは前回ルーチンにて計測されたボイラ給水管１３内の圧力と、今回ルーチンで計測されたボイラ給水管１３内の圧力との差に基づき、酸素ガス量調整手段としてのコントロールバルブ１９の目標開度量を算出するための補正値（第２の補正値）を算出するようにした。
【００２８】
これに対し、事前にボイラ給水管１３内の圧力に対する補正値を予め設定しておき、今回のルーチンで計測されたボイラ給水管１３内の圧力に基づき、酸素ガス量調整手段としてのコントロールバルブ１９の基準開度量を補正するようにしてもよい。この場合、例えば、計測された圧力値に所定の係数を積算したものを補正値としてもよい。
【００２９】
（２）基準開度量を補正するために必要なデータはボイラ給水管１３内の圧力と、ボイラ水中の溶存酸素濃度だけとしてもよい。
（３）基準開度量を補正するために必要なデータはボイラ給水管１３内の圧力と、酸素供給管１７を流動する酸素ガスの流量だけとしてもよい。
【００３０】
【発明の効果】
請求項１に記載の発明によれば、ボイラ給水管内の圧力が変動しても、素早く適量の酸素ガスをボイラ給水管内に効率良く供給することができる。その結果、効率よくボイラ給水管内面に腐食防止皮膜を形成することができるとともに、ボイラへの悪影響を減少できる。
【図面の簡単な説明】
【図１】本発明を具体化した一実施形態における概略的な回路図。
【図２】コントローラの制御内容を示すフローチャート。
【図３】（ａ）は本実施の形態におけるボイラ水流量、ボイラ給水管内の圧力、酸素ガス流量の関係を記すグラフ。（ｂ）は従来技術におけるボイラ水流量、ボイラ給水管内の圧力、酸素ガス流量の関係を記すグラフ。
【符号の説明】
１２…ボイラ、１３…ボイラ給水管、１８…酸素ガス供給手段としての酸素ボンベ、１９…酸素ガス量調整弁としてのコントロールバルブ、１５…圧力計測手段としての圧力計、Ｃ…基準開度量決定手段、補正手段、制御手段としてのコントローラ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a corrosion prevention film forming apparatus for a boiler water pipe that forms a corrosion prevention film for iron oxide on the inner surface of a boiler water supply pipe that supplies boiler water to a boiler, for example, in a steam power plant.
[0002]
[Prior art]
Conventionally, an oxygen cylinder is connected to an intermediate portion of a boiler water supply pipe constituting a corrosion prevention film forming apparatus for a boiler water supply pipe via an oxygen gas supply pipe. A control valve is provided in the middle of the oxygen gas supply pipe, and oxygen gas is pumped from the oxygen cylinder into the boiler water supply pipe in accordance with the opening of the control valve. When this oxygen gas is pumped into the boiler water supply pipe, a corrosion prevention film of iron oxide is formed on the inner surface of the boiler water supply pipe.
[0003]
The control valve is driven and controlled by a controller. The controller calculates a reference opening amount based on a predetermined condition based on the flow rate of boiler water flowing through the boiler feed pipe. Then, the calculated reference opening amount is corrected based on a desired correction value, and becomes the final target opening amount. The controller drives and controls the control valve so as to achieve the calculated target opening amount. The correction value used when calculating the target opening amount is calculated based on the flow rate of oxygen gas flowing through the oxygen gas supply pipe (the amount of oxygen gas injected into the boiler feed pipe) and the dissolved oxygen concentration in the boiler water. Is done.
[0004]
[Problems to be solved by the invention]
However, the corrosion prevention film forming apparatus has the following problems.
[0005]
When the pressure in the boiler water supply pipe becomes high due to the pressure fluctuation in the boiler water supply pipe, the pressure becomes resistance and it is difficult to inject oxygen gas. In this case, since the flow rate of oxygen gas decreases, the controller increases the opening amount of the control valve to increase the injection amount of oxygen gas.
[0006]
For example, as shown in the graph of FIG. 3B, it is assumed that the flow rate of boiler water is 1800 m 3 / h and the dissolved oxygen concentration is 0.1 ppm (α range in FIG. 3). In this case, the prescribed oxygen injection amount is 2.1 liters / min according to a predetermined calculation formula. Therefore, the controller drives and controls the control valve so that the injection amount of oxygen gas is 2.1 liter / min.
[0007]
Further, it is assumed that the flow rate of boiler water detected in the next routine is 1800 m 3 / h, which is the same flow rate as in the previous routine. Then, it is assumed that the pressure in the boiler water supply pipe has increased by 3 kg / cm 2 from the previous control (previous routine) due to the pressure fluctuation in the boiler water supply pipe (β range in the figure). At this time, since the flow rate of the boiler water does not change even if the pressure fluctuation occurs in the boiler feed pipe, the controller holds the opening amount as a reference of the control valve at the same opening amount as that in the previous routine. As the pressure in the boiler feed pipe increases, the amount of oxygen gas injected into the boiler feed pipe decreases.
[0008]
That is, as the pressure in the boiler feed pipe rises, oxygen gas is less likely to be injected into the boiler feed pipe. Accordingly, since the oxygen gas flow rate and the dissolved oxygen concentration value also decrease accordingly, the controller increases the opening amount of the control valve so that the dissolved oxygen concentration in the boiler water becomes a predetermined concentration. Further, as the pressure in the boiler feed pipe decreases, oxygen gas is easily injected into the boiler feed pipe. Accordingly, since the oxygen gas flow rate and the dissolved oxygen concentration value increase accordingly, the controller decreases the opening amount of the control valve so that the dissolved oxygen concentration in the boiler water becomes a predetermined concentration (γ range in the figure).
[0009]
However, in order to correct the reference opening amount based on the dissolved oxygen concentration and the flow rate of oxygen gas, it takes a long time t1 and t2 to determine the optimum oxygen gas injection amount. That is, since the controller corrects the opening amount of the control valve based on the values of the oxygen gas flow rate and the dissolved oxygen concentration, the flow rate of the boiler water does not change even if the pressure of the boiler feed pipe changes. When the pressure in the boiler water supply pipe has changed significantly, the controller took a long time to inject the specified oxygen injection amount into the boiler water supply pipe.
[0010]
In this case, since the dissolved oxygen concentration in the boiler water varies for a long time, there is a problem that the boiler feed pipe and the boiler are adversely affected and an antioxidant coating cannot be efficiently formed on the inner surface of the boiler feed pipe. It was.
[0011]
The present invention has been made in order to solve the above problems, and its purpose is to provide boiler feed water that can quickly bring the dissolved oxygen concentration to the specified dissolved oxygen concentration even if the flow rate and pressure of the boiler water change. An object of the present invention is to provide an apparatus for forming a corrosion prevention film on a pipe.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, oxygen gas is injected from an oxygen gas supply means into a boiler water supply pipe for supplying boiler water to a boiler, and iron oxide corrosion prevention is performed on the inner surface of the boiler supply pipe. In the corrosion prevention film forming apparatus for forming a film, an oxygen gas flow rate adjusting valve for adjusting the amount of oxygen gas held at a constant pressure injected into the boiler feed pipe from the oxygen gas supply means, and in the boiler feed pipe A reference opening amount determining means for determining an opening amount serving as a reference of the oxygen gas flow rate adjusting valve based on a flow rate of boiler water flowing through the boiler, and a reference opening amount determined by the reference opening amount determining means in the boiler feed pipe based of the pressure and concentration of oxygen dissolved in boiler water, and correcting means for correcting the optimal opening degree of the oxygen gas flow rate adjusting valve, the optimum opening amount corrected by the correction means So as to, as its gist in that a control means for driving and controlling the oxygen gas flow rate adjusting valve.
[0013]
(Function)
Therefore, in the first aspect of the invention, first, the reference opening amount determining means is determined by the reference opening amount determining means based on the flow rate of the boiler water flowing in the boiler feed pipe. Next, the reference opening amount is corrected to the optimum opening amount by the correcting means. Then, the oxygen gas flow rate adjustment valve is driven and controlled by the control means so that the corrected optimum opening amount is obtained.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, the pump 11 and the boiler 12 are connected by a boiler feed pipe 13. As the pump 11 is driven, boiler water is supplied from the boiler feed pipe 13 to the boiler 12. Connected to the boiler feed pipe 13 is a boiler water flow meter 14 for measuring the flow rate of boiler water flowing through the boiler feed pipe 13. Further, a pressure gauge 15 for measuring the pressure in the boiler water supply pipe 13 is connected to the boiler water supply pipe 13.
[0015]
The boiler feed pipe 13 is connected with a concentration meter 16 for measuring the concentration of oxygen dissolved in the boiler water. An oxygen cylinder 18 is connected to a portion of the boiler water supply pipe 13 between the pressure gauge 15 and the concentration meter 16 via an oxygen supply pipe 17. Note that the pressure of the oxygen cylinder 18 does not change and is kept constant. A control valve 19 as an oxygen gas flow rate adjustment valve is connected to the oxygen supply pipe 17. An oxygen flow meter 20 for measuring the flow rate of oxygen flowing through the oxygen supply pipe 17 is connected to a portion of the oxygen supply pipe 17 upstream of the control valve 19. Furthermore, an opening / closing valve 21 and a check valve 22 for preventing the backflow of boiler water are provided at a site where the oxygen supply pipe 17 is connected to the boiler water supply pipe 13.
[0016]
Next, the electrical configuration in the present embodiment will be described.
The boiler water flow meter 14, the oxygen flow meter 20, the pressure meter 15, the concentration meter 16, the control valve 19, and the opening / closing valve 21 are connected to the controller C as the reference opening amount determination means, the correction means, and the control means. . The controller C individually inputs measurement signals from each instrument, and determines the opening degree of the control valve 19 based on the measurement results.
[0017]
Next, the control contents executed by the controller C will be described with reference to the flowchart of FIG.
In step 101, a measured value (a flow rate of boiler water flowing through the boiler feed pipe 13) is input from the boiler water flow meter 14. In the next step 102, the reference opening amount of the control valve 19 is calculated from the input boiler water flow rate. In step 103, the control valve 19 is driven to open so that the reference opening amount calculated in step 102 is obtained. In subsequent step 104, it opens the opening and closing valve 21, supplying oxygen to the boiler feed water pipe 13.
[0018]
In the next step 105, measured values (the flow rate of oxygen gas flowing through the oxygen supply pipe 17, the dissolved oxygen concentration dissolved in boiler water) are input from the oxygen flow meter 20 and the concentration meter 16, respectively. In the next step 106, a first correction value for correcting the opening degree of the control valve 19 is calculated based on the input measurement value. In the next step 107, a measured value (pressure in the boiler feed pipe 13) is input from the pressure gauge 15.
[0019]
In step 108, the difference between the pressure value measured in the previous routine and the pressure value measured in the current routine is calculated. In step 109, a second correction value for correcting the opening degree of the control valve 19 is calculated based on the calculated pressure difference. In step 110, the reference opening degree calculated in step 102 is corrected based on the two correction values calculated. In step 111, the corrected opening amount is set as the target opening amount, and the control valve 19 is driven and controlled so as to be the target opening amount. And it returns to step 101 again and repeats subsequent processes.
[0020]
Next, the operation in the present embodiment will be described.
When boiler water flows through the boiler feed pipe 13, a predetermined amount of the control valve 19 and the on-off valve 21 are opened based on the flow rate of the boiler water flowing through the boiler feed pipe 13. Thus, oxygen gas is supplied from the oxygen cylinder 18 to the boiler feed pipe 13 through the oxygen supply pipe 17. The oxygen gas supplied to the boiler feed pipe 13 is dissolved in the boiler water. Then, based on the oxygen concentration value in the boiler water in which the oxygen gas is dissolved and the oxygen flow rate value flowing in the oxygen supply pipe 17, the first correction value used to determine the target opening amount of the control valve 19 is calculated. The
[0021]
At the same time, a second correction value used for determining the target opening degree of the control valve 19 is calculated based on the pressure fluctuation in the boiler feed pipe 13. Based on these correction values, the opening amount of the control valve 19 is corrected to an appropriate value.
[0022]
Therefore, for example, when the flow rate of boiler water is 1800 m 3 / h and the dissolved oxygen concentration in boiler water is 0.1 ppm, the injection amount is 2.1 liters / min according to a predetermined calculation formula. The controller C drives and controls the control valve 19 so that the oxygen gas injection rate is 2.1 liters / min. Then, it is assumed that the flow rate of boiler water detected in the next routine is 1800 m 3 / h, which is the same flow rate as in the previous routine. On the other hand, it is assumed that the pressure in the boiler feed pipe 13 is 6 kg / cm 2 which is 3 kg / cm 2 higher than the previous routine.
[0023]
In the present embodiment, the controller C uses the detected value from the pressure gauge 15 to detect that the pressure in the boiler water supply pipe 13 has increased by 3 kg / cm 2 even though the flow rate of the boiler water has not changed. It detects and corrects the opening degree of the control valve 19 to increase the opening degree as compared with the previous routine. Thereby, even if the pressure of the boiler feed pipe 13 is high and oxygen gas is hardly injected into the boiler feed pipe 13, the opening amount of the control valve 19 is increased, and thus the boiler feed pipe 13 is quickly defined. An amount of oxygen can be supplied.
[0024]
As described in detail above, in the present embodiment, the dissolved oxygen concentration in the boiler water and the oxygen gas are used as data for correcting the reference opening amount determined based on the flow rate of the boiler water flowing through the boiler feed pipe 13. The flow rate and the pressure in the boiler feed pipe 13 were used. Thereby, even if the pressure of the boiler feed pipe 13 is high and oxygen gas is hardly injected into the boiler feed pipe 13, the opening amount of the control valve 19 is increased, and thus the boiler feed pipe 13 is quickly defined. An amount of oxygen can be supplied.
[0025]
As a result, as shown in the graph of FIG. 3 (a), the amount of oxygen gas injected into the boiler feed pipe 13 is quickly defined by adding the increase or decrease in the pressure in the boiler feed pipe 13 to the correction factor. The amount can be corrected and the correspondence can be achieved in a short time t1 ′ (<t1) and t2 ′ (<t2). As a result, it is possible to prevent the dissolved oxygen concentration in the boiler water from varying, and as a result, it is possible to efficiently form a corrosion prevention film on the inner surface of the boiler feed pipe 13 and to reduce the adverse effects on the boiler 12.
[0026]
Further, the reference opening amount can be corrected and updated based on the pressure difference between the pressure value in the boiler feed pipe 13 measured in the previous routine and the pressure value in the boiler feed pipe 13 measured in the current routine. Thereby, the oxygen gas injection amount in consideration of the pressure fluctuation in the boiler feed pipe 13 is accurately determined, and can be quickly stabilized against the fluctuation of the dissolved oxygen concentration in the boiler water.
[0027]
In addition, you may implement this invention as follows.
(1) In the above embodiment, the controller C as the control means is based on the difference between the pressure in the boiler feed pipe 13 measured in the previous routine and the pressure in the boiler feed pipe 13 measured in the current routine. A correction value (second correction value) for calculating the target opening degree of the control valve 19 as the oxygen gas amount adjusting means is calculated.
[0028]
On the other hand, a correction value for the pressure in the boiler feed pipe 13 is set in advance, and the control valve 19 as an oxygen gas amount adjusting means is based on the pressure in the boiler feed pipe 13 measured in this routine. The reference opening amount may be corrected. In this case, for example, a value obtained by adding a predetermined coefficient to the measured pressure value may be used as the correction value.
[0029]
(2) The data necessary for correcting the reference opening amount may be only the pressure in the boiler feed pipe 13 and the dissolved oxygen concentration in the boiler water.
(3) The data necessary for correcting the reference opening amount may be only the pressure in the boiler feed pipe 13 and the flow rate of oxygen gas flowing through the oxygen supply pipe 17.
[0030]
【The invention's effect】
According to the first aspect of the present invention, an appropriate amount of oxygen gas can be quickly and efficiently supplied into the boiler water supply pipe even if the pressure in the boiler water supply pipe fluctuates. As a result, it is possible to efficiently form a corrosion prevention film on the inner surface of the boiler water supply pipe and to reduce adverse effects on the boiler.
[Brief description of the drawings]
FIG. 1 is a schematic circuit diagram in an embodiment embodying the present invention.
FIG. 2 is a flowchart showing control contents of a controller.
FIG. 3A is a graph showing the relationship between the boiler water flow rate, the pressure in the boiler feed pipe, and the oxygen gas flow rate in the present embodiment. (B) is a graph showing the relationship between the boiler water flow rate, the pressure in the boiler feed pipe, and the oxygen gas flow rate in the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 12 ... Boiler, 13 ... Boiler feed pipe, 18 ... Oxygen cylinder as oxygen gas supply means, 19 ... Control valve as oxygen gas amount adjustment valve, 15 ... Pressure gauge as pressure measurement means, C ... Reference | standard opening amount determination means , Controller as correction means, control means.

Claims (1)

ボイラへボイラ水を供給するボイラ給水管に酸素ガス供給手段から酸素ガスを注入し、当該ボイラ給水管内面に酸化鉄の腐食防止皮膜を形成する腐食防止皮膜形成装置において、
前記酸素ガス供給手段からボイラ給水管内に注入される一定圧力に保持された酸素ガスの量を調整するための酸素ガス流量調整弁と、
前記ボイラ給水管内を流動するボイラ水の流量に基づき、前記酸素ガス流量調整弁の基準となる開度量を決定する基準開度量決定手段と、
前記基準開度量決定手段により決定された基準開度量を、ボイラ給水管内の圧力とボイラ水中に溶存する酸素の濃度とに基づき、前記酸素ガス流量調整弁の最適開度量に補正する補正手段と、
前記補正手段により補正された最適開度量となるように、前記酸素ガス流量調整弁を駆動制御する制御手段と
を備えたボイラ給水管の腐食防止皮膜形成装置。In a corrosion prevention film forming apparatus for injecting oxygen gas from an oxygen gas supply means into a boiler water supply pipe that supplies boiler water to a boiler, and forming an iron oxide corrosion prevention film on the inner surface of the boiler water supply pipe,
An oxygen gas flow rate adjustment valve for adjusting the amount of oxygen gas held at a constant pressure injected into the boiler feed pipe from the oxygen gas supply means;
A reference opening amount determining means for determining an opening amount serving as a reference of the oxygen gas flow rate adjustment valve based on a flow rate of boiler water flowing in the boiler feed pipe;
Correction means for correcting the reference opening amount determined by the reference opening amount determining means to the optimum opening amount of the oxygen gas flow rate adjustment valve based on the pressure in the boiler feed pipe and the concentration of oxygen dissolved in the boiler water;
An apparatus for forming a corrosion prevention film on a boiler water supply pipe, comprising: control means for drivingly controlling the oxygen gas flow rate adjusting valve so as to obtain an optimum opening amount corrected by the correction means.
JP19458196A 1996-07-24 1996-07-24 Boiler feed pipe corrosion prevention film forming device Expired - Fee Related JP3655014B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP19458196A JP3655014B2 (en) 1996-07-24 1996-07-24 Boiler feed pipe corrosion prevention film forming device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP19458196A JP3655014B2 (en) 1996-07-24 1996-07-24 Boiler feed pipe corrosion prevention film forming device

Publications (2)

Publication Number Publication Date
JPH1038211A JPH1038211A (en) 1998-02-13
JP3655014B2 true JP3655014B2 (en) 2005-06-02

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108341543A (en) * 2018-03-01 2018-07-31 北京自由华程环保技术有限公司 A kind of water purification system and its application method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002081614A (en) * 2000-09-07 2002-03-22 Babcock Hitachi Kk Device and method for injecting oxygen into boiler

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108341543A (en) * 2018-03-01 2018-07-31 北京自由华程环保技术有限公司 A kind of water purification system and its application method

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