JPH07207474A - Controlled potential automatic control type electrical protection method using galvanic anode method - Google Patents
Controlled potential automatic control type electrical protection method using galvanic anode methodInfo
- Publication number
- JPH07207474A JPH07207474A JP6018847A JP1884794A JPH07207474A JP H07207474 A JPH07207474 A JP H07207474A JP 6018847 A JP6018847 A JP 6018847A JP 1884794 A JP1884794 A JP 1884794A JP H07207474 A JPH07207474 A JP H07207474A
- Authority
- JP
- Japan
- Prior art keywords
- potential
- transistor
- galvanic anode
- anticorrosion
- current
- 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.)
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Links
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- Prevention Of Electric Corrosion (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、流電陽極方式のカソー
ド防食法において、照合電極で測定された被防食体の電
位を流電陽極の電位より貴な範囲の任意の電位に常時一
定に保持する電位自動制御式電気防食法およびそのため
の簡便な定電位自動制御式電気防食装置に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in a cathodic protection method of a galvanic anode system, constantly sets the potential of an object to be corroded measured by a reference electrode to an arbitrary potential within a range nobler than the potential of the galvanic anode. The present invention relates to an electric potential-controlled electrocorrosion protection method for holding and a simple constant-potential automatically-controlled electrocorrosion protection device therefor.
【０００２】[0002]
【従来の技術】電気防食法は、海水中、河川水中や地中
等に設置された金属構造物や埋設管、あるいはコンクリ
ート中の鉄筋、さらに工業用水や有機・無機の液体に接
する化学装置等の腐食を防止する方法として利用され、
港湾、橋梁等のインフラストラクチュアや各分野の産業
での防食に大きな効果を挙げている。2. Description of the Related Art The cathodic protection method is used for metal structures and buried pipes installed in seawater, river water, underground, etc., steel bars in concrete, and chemical equipment in contact with industrial water and organic / inorganic liquids. Used as a method to prevent corrosion,
It is highly effective in preventing corrosion in infrastructure such as ports and bridges and in industries in each field.
【０００３】電気防食法においては、商用交流の整流電
源や電池等の外部電源と不溶性電極を用いてカソード電
流を被防食体に供給する外部電源方式と、マグネシウム
合金、アルミニウム合金または亜鉛合金等の卑電位の金
属製の流電陽極を被防食体に直結し、両者の電位差を利
用し被防食体に対するカソード電流を発生する流電陽極
方式とがある。いずれの方式においても、被防食体は、
その腐食が停止する防食電位まで分極するに必要な防食
電流を加えられることが重要である。環境の電気伝導
度、溶存酸素濃度、流速や温度等の条件の変化や被防食
体のエレクトロコーティングの進行状態等により、防食
電流の必要量が異なるので、防食電流はこれら条件に対
応して調節し、過不足のないようにするのが効果的かつ
経済的に防食するために肝要である。In the cathodic protection method, an external power supply method of supplying a cathode current to the object to be protected by using an external power supply such as a commercial AC rectification power supply or a battery and an insoluble electrode, and a magnesium alloy, an aluminum alloy or a zinc alloy. There is a galvanic anode system in which a metal galvanic anode having a base potential is directly connected to a body to be protected and a potential difference between the two is used to generate a cathode current to the body to be protected. In either method,
It is important to be able to apply the anticorrosion current necessary to polarize the corrosion potential to stop its corrosion. The required amount of anticorrosion current varies depending on changes in conditions such as environmental electrical conductivity, dissolved oxygen concentration, flow velocity and temperature, and the progress of electrocoating of the object to be protected, so the anticorrosion current is adjusted according to these conditions. However, it is essential to prevent excess and deficiency in order to prevent corrosion effectively and economically.
【０００４】しかし、最近、防食対象の拡大から、流電
陽極に被防食体を直結し、流電陽極の接地抵抗（接水抵
抗）の調節に基づく電流分布の変化により電位制御する
定電流式の防食法では、過防食により−１Ｖ（飽和カロ
メル電極基準、以下同様）以下にもなることがあり、水
素脆化の恐れのある高張力鋼やチタンの防食には適用で
きない。すなわち、高張力鋼に対しては−９５０ｍＶ、
チタンでは−７００ｍＶ以下にならないように、現用の
卑電位の流電陽極より遥かに貴な電位領域に調節する必
要が生じてきた。However, recently, due to the expansion of the object of corrosion protection, a constant current type in which a body to be protected is directly connected to the galvanic anode and the potential is controlled by changing the current distribution based on the adjustment of the ground resistance (water contact resistance) of the galvanic anode. In the anticorrosion method of No. 1, it may be less than -1 V (saturated calomel electrode standard, the same applies below) due to overcorrosion, and it cannot be applied to the anticorrosion of high-strength steel or titanium that may be subject to hydrogen embrittlement. That is, -950 mV for high strength steel,
With titanium, it has become necessary to adjust the potential to a much more noble potential region than the current base-current galvanic anode so that it does not fall below -700 mV.
【０００５】一方、耐食性の要求からステンレス鋼製の
淡水用タンクが使用されるようになっているが、装置の
構造的隙間や沈下した砂の下等が異物に覆われて溶存酸
素の供給が制限されるところでは、酸素濃度の低下で不
動態が破壊し、隙間腐食が生じることが多い。この隙間
腐食はステンレス鋼の電位を−０．３〜−０．５Ｖに保
持するカソード防食法で防食することができる。しか
し、主に外部電源方式の定電流カソード防食法が適用さ
れている現在では、用いる電源に制御性がないので、ス
テンレス鋼の活性／不動態の臨界電位を大きく超えて活
性電位領域まで分極し過防食状態で適用されている。こ
れらの過防食を防止するためには、上記の限界電位を超
えないように被防食体の電位を一定に保持する必要があ
り、電位の自動制御が必要となる。On the other hand, a tank for fresh water made of stainless steel has come to be used due to the requirement of corrosion resistance. However, the structural gap of the apparatus and the bottom of the sinking sand are covered with foreign matter to supply the dissolved oxygen. Where it is limited, the decrease in oxygen concentration often destroys the passivation, resulting in crevice corrosion. This crevice corrosion can be prevented by a cathodic protection method in which the potential of stainless steel is maintained at -0.3 to -0.5V. However, at present, when the constant current cathodic protection method of the external power supply method is mainly applied, there is no controllability in the power supply to be used, so that it polarizes far beyond the active / passive critical potential of stainless steel to the active potential region. It is applied in a state of over-corrosion protection. In order to prevent these over-corrosion prevention, it is necessary to keep the potential of the body to be protected constant so as not to exceed the above-mentioned limit potential, and automatic control of the potential is required.
【０００６】このため、外部電源法においては、電源と
して定電位装置を用い、照合電極で測定した被防食体の
電位が設定した防食電位や最卑安全電位になるように電
流を自動調節する。この電位の自動制御は外部電源法で
はよく用いられる方法であるが、流電陽極法では適用例
が見当たらない。これは、１個の流電陽極の電気容量が
あまり大きくないので分散して取り付けられる多数の陽
極に対し、外部電源法のように１個の陽極に集中して制
御することが困難であるためである。Therefore, in the external power source method, a constant potential device is used as a power source, and the current is automatically adjusted so that the potential of the anticorrosion object measured by the reference electrode becomes the set anticorrosion potential or the base most safe potential. This automatic control of potential is a method often used in the external power source method, but no application example is found in the galvanic anode method. This is because the electric capacity of one galvanic anode is not so large that it is difficult to concentrate on one anode like the external power supply method and control it with respect to a large number of anodes that are distributed and attached. Is.
【０００７】しかし、この外部電源による定電位法で
は、大容量の定電位装置は高価であり、大きな構造物の
防食にはあまり利用されておらず、またケーブルの事故
も多く経済的でないので、安価・確実な定電位装置の開
発が望まれていた。However, in this potentiostatic method using an external power source, a large-capacity potentiostatic device is expensive, is not often used for corrosion protection of large structures, and many cable accidents are not economical. It was desired to develop an inexpensive and reliable potentiostatic device.
【０００８】[0008]
【発明が解決しようとする課題】本発明は、これら従来
技術の課題を解決し、流電陽極方式のカソード防食にお
いて、照合電極で測定された被防食体の電位を設定電位
に常時一定に維持するように流電陽極からの防食電流を
調節する方式の電位自動制御式電気防食法、およびその
ための簡単な定電位自動制御装置を提供することを目的
とする。DISCLOSURE OF THE INVENTION The present invention has solved these problems of the prior art, and in cathodic protection of galvanic anode method, the potential of the corrosion-prevented body measured by the reference electrode is always kept constant at the set potential. It is an object of the present invention to provide a potential automatic control type galvanic protection method of adjusting the corrosion protection current from the galvanic anode as described above, and a simple constant potential automatic control device therefor.
【０００９】[0009]
【課題を解決するための手段】本発明者は、上記目的に
沿って鋭意検討の結果、流電陽極は本来“電気の塊”と
も言うべきものであって、溶解して電流を発生する性
質、すなわち換言すれば電源と対極が合体したものであ
ることに着目し、この流電陽極と被防食体とのガルバニ
対のカップル電流を自由に調節し、被防食体の電位が目
的の値に保持される最適電流に調節する方法において、
極めて小容量の別個の電源で駆動される電圧増幅器等を
利用して、電流を制御する方法を見出した。従って、外
部電源方式のように外部から電気エネルギーを持ち込む
必要が無いので、エネルギー輸送のための長いケーブル
が不要となり、外部電源方式の致命的欠点となったケー
ブルの経年損傷、絶縁不良等の事故の恐れのない簡単か
つ安定な電気防食装置を見出し、これを用いることによ
り安価、確実な定電位自動制御式電気防食法を確立し
た。Means for Solving the Problems The inventors of the present invention have made earnest studies in accordance with the above-mentioned object, and as a result, the galvanic anode should originally be called an "lump of electricity", and it has the property of melting and generating an electric current. In other words, paying attention to the fact that the power source and the counter electrode are combined, that is, the galvanic couple current between the galvanic anode and the corrosion-preventing body is freely adjusted, and the potential of the corrosion-preventing body becomes a target value. In the method of adjusting to the optimum current to be held,
We have found a method of controlling the current by using a voltage amplifier or the like driven by an extremely small capacity separate power supply. Therefore, unlike the external power supply system, there is no need to bring in electrical energy from the outside, so long cables for energy transportation are not required, and accidents such as aging cable damage and insulation failure, which were fatal drawbacks of the external power supply system. We have found a simple and stable cathodic protection device that does not have the risk of using, and by using it, we have established a cheap and reliable constant potential automatic control type cathodic protection method.
【００１０】すなわち、本発明の流電陽極方式定電位自
動制御式電気防食法は、バイポーラ型パワートランジス
タのコレクタとエミッタまたは電界効果型パワートラン
ジスタのドレインとソースにそれぞれ流電陽極と被防食
体とを接続し、照合電極で測定した被防食体の電位と設
定電位との差電圧を該トランジスタとは別個の電源で駆
動される電圧増幅器で増幅し、該電圧増幅器の出力をも
って該トランジスタのコレクタ電流またはドレイン電流
を調節することにより被防食体の電位を制御し、設定電
位に保持することを特徴とする。That is, in the galvanic anode type constant potential automatic control type galvanic protection method of the present invention, a galvanic anode and an anticorrosion body are respectively provided in the collector and emitter of a bipolar power transistor or the drain and source of a field effect power transistor. The difference voltage between the potential of the corrosion-prevented body measured by the reference electrode and the set potential is amplified by a voltage amplifier driven by a power source separate from the transistor, and the output of the voltage amplifier is used to collect the collector current of the transistor. Alternatively, it is characterized in that the potential of the corrosion-preventing body is controlled by adjusting the drain current and held at the set potential.
【００１１】また、本発明の定電位自動制御式電気防食
装置は、流電陽極と被防食体および該被防食体の電位を
測定する照合電極の３電極よりなり、該流電陽極と該被
防食体に接続されるパワートランジスタ、被防食体の目
的とする電位の値を設定する電位設定部、および測定さ
れる該被防食体の電位と設定電圧の差電圧を増幅し、も
って該トランジスタを制御する電圧増幅器を有し、該電
圧増幅器および電位設定部を駆動し、該トランジスタと
は異なる電源を備えることを特徴とする。The constant potential automatic control type anticorrosion device of the present invention comprises a galvanic anode, an object to be corroded, and three electrodes of a reference electrode for measuring the potential of the object to be corroded. A power transistor connected to the anticorrosion body, a potential setting section for setting a desired potential value of the anticorrosion body, and a voltage difference between the measured potential of the anticorrosion body and the set voltage are amplified, and thus the transistor is provided. It has a voltage amplifier for controlling, drives the voltage amplifier and the potential setting unit, and is provided with a power supply different from the transistor.
【００１２】以下、本発明を図面に基づいて具体的に説
明する。図１は、本発明の流電陽極方式定電位自動制御
式電気防食法に用いられる電気防食装置の一例を示す説
明図である。同図において、１は海洋構造物やステンレ
ス鋼製タンク等の被防食体、２はマグネシウム合金、ア
ルミニウム合金や亜鉛合金等の卑な電位の金属製の流電
陽極、３は被防食体１の電位を計測する例えば飽和カロ
メル電極、塩化銀電極のような照合電極、４は例えば水
道水等の環境を表わす。５は電流制御のための電流容量
の大きいパワートランジスタであり、６は演算増幅器の
ような電圧増幅器を示す。また、７は保持したい被防食
体１の電位（使用する照合電極基準の値）に対応する電
圧を設定する電位設定部である。８および８′は外界よ
りの電撃から電子回路を保護するためのダイオードやア
レスタ等の入力保護素子である。９は該トランジスタと
並列に流電陽極と被防食体との間に付加的に接続される
こともある電流分流用の固定抵抗である。The present invention will be specifically described below with reference to the drawings. FIG. 1 is an explanatory view showing an example of the galvanic protection apparatus used in the galvanic anode type constant potential automatic control type galvanic protection method of the present invention. In the figure, 1 is an object to be protected such as a marine structure or a tank made of stainless steel, 2 is a galvanic anode made of a metal having a base potential such as magnesium alloy, aluminum alloy or zinc alloy, 3 is an object to be protected 1. Reference electrodes 4 such as a saturated calomel electrode and a silver chloride electrode for measuring an electric potential represent an environment such as tap water. Reference numeral 5 is a power transistor having a large current capacity for current control, and 6 is a voltage amplifier such as an operational amplifier. Reference numeral 7 is a potential setting unit for setting a voltage corresponding to the potential of the corrosion-prevented body 1 to be held (reference electrode reference value to be used). Reference numerals 8 and 8'denotes input protection elements such as diodes and arresters for protecting electronic circuits from electric shock from the outside world. Reference numeral 9 is a fixed resistor for current shunting, which may be additionally connected in parallel with the transistor between the galvanic anode and the body to be protected.
【００１３】以下、例えば水道水中において、被防食体
１としてステンレス鋼製タンク、流電陽極２としてはマ
グネシウム系合金陽極（陽極電位：−１．５Ｖ）を用い
る例で、図１によって本発明の電気防食法の内容を説明
する。Hereinafter, for example, in tap water, a stainless steel tank is used as the body 1 to be protected and a magnesium alloy anode (anode potential: -1.5 V) is used as the galvanic anode 2. Explain the contents of the cathodic protection method.
【００１４】水道水４の中で流電陽極２からの防食電流
は被防食体１に流入し、外部回路で被防食体１から流電
陽極２に戻ろうとするが、外部回路にはパワートランジ
スタ５のコレクタ・エミッタ間の内部抵抗が介在するの
で、電流はこの内部抵抗で制御される。飽和カロメル電
極を始め塩化銀電極や亜鉛金属電極のような照合電極３
は被防食体１であるステンレス鋼製タンク内面の隙間部
に近付けて設置し、防食電流と水道水の高抵抗とで生じ
る電圧降下を計り込まないようにして測定したステンレ
ス鋼製タンクの電位に相当する電圧Ｅｐ（照合電極３と
被防食体１の電位の差の電圧）と、電位設定部７で設定
された被防食体１の目的電位の順に相当する電圧Ｅｓと
の二つの電位は、演算増幅器のような電圧増幅器６の差
動の入力端子に入力される。そして電圧Ｅｐは設定電圧
Ｅｓと比較され、その偏差Ｅｐ−Ｅｓは電圧増幅器６で
増幅され、その出力はパワートランジスタ５のベースま
たはゲートにフィードバックされ、トランジスタ５の内
部抵抗を変化させる。その結果、コレクタ・エミッタ間
またはドレイン・ソース間を流れる防食電流が変化し、
従って被防食体１の電位Ｅｐが変化する。この一連の変
化は、被防食体１の電位Ｅｐが設定電圧Ｅｓに等しくな
るまで続き、被防食体１の電位Ｅｐは目的の設定電位Ｅ
ｓに常時等しく一定に維持されることになる。In the tap water 4, the anticorrosion current from the galvanic anode 2 flows into the anticorrosion body 1 and tries to return from the anticorrosion body 1 to the galvanic anode 2 in an external circuit. Since the internal resistance between the collector and the emitter of 5 exists, the current is controlled by this internal resistance. Matching electrode 3 such as saturated calomel electrode, silver chloride electrode and zinc metal electrode
Is installed close to the gap on the inner surface of the stainless steel tank, which is the body to be protected 1, and is the potential of the stainless steel tank measured so as not to measure the voltage drop caused by the corrosion protection current and the high resistance of tap water. Two potentials, the corresponding voltage Ep (voltage of the potential difference between the reference electrode 3 and the corrosion-preventing body 1) and the voltage Es corresponding to the target potential of the corrosion-preventing body 1 set by the potential setting unit 7, It is input to the differential input terminal of the voltage amplifier 6 such as an operational amplifier. Then, the voltage Ep is compared with the set voltage Es, the deviation Ep-Es is amplified by the voltage amplifier 6, and the output is fed back to the base or gate of the power transistor 5 to change the internal resistance of the transistor 5. As a result, the anti-corrosion current flowing between collector-emitter or drain-source changes,
Therefore, the potential Ep of the body 1 to be protected changes. This series of changes continues until the potential Ep of the body 1 to be protected becomes equal to the set voltage Es, and the potential Ep of the body 1 to be protected is the target set potential E.
s will always be kept equal and constant.
【００１５】図１ではバイポーラ型のパワートランジス
タを例として図示したが、該トランジスタ５に電界効果
型パワートランジスタを使用するときには、該トランジ
スタ５のドレインとソースはそれぞれは流電陽極２と被
防食体１に接続され、ゲート電圧を調節してドレイン・
ソース間の電圧が制御される。In FIG. 1, a bipolar type power transistor is shown as an example, but when a field effect type power transistor is used as the transistor 5, the drain and source of the transistor 5 are the galvanic anode 2 and the body to be protected. It is connected to 1 and the drain voltage is adjusted by adjusting the gate voltage.
The voltage between the sources is controlled.
【００１６】上述のように、この電気防食法において
は、環境条件等が大幅に変化し防食電流が変動しても、
被防食体の電位は、流電陽極の陽極電位よりかなり貴な
広い電位領域において任意の目的の値に常に一定に保持
できる。As described above, in this cathodic protection method, even if the environmental conditions and the like change significantly and the anticorrosion current fluctuates,
The potential of the body to be protected can always be kept constant at any desired value in a wide potential range that is considerably nobler than the anode potential of the galvanic anode.
【００１７】さらに、この電気防食法においては、もう
一つの大きな特徴がある。それは、電流制御に使われる
パワートランジスタ５の電流は流電陽極２から供給され
るので、防食電流の大小に関係なく出力用のトランジス
タ５のための外部電源は一切必要なく、ベース電流（あ
るいはゲート電圧）を調節する偏差増幅回路を駆動する
ための極めて小容量の電源が必要となるのみで、小電力
でよいので電池駆動でも長期間この電気防食装置を作動
させ、連続的な電位制御が可能なことである。このよう
に電源が小容量・長寿命で、回路の部品数も図示のよう
に少ないので、乾電池の電源を含め全体の装置が極めて
小型にでき、水密構造にして土中や水中の流電陽極に密
接して取り付けることが可能で、これまで外部整流電源
を用いる自動制御式の電気防食法で故障の主因であった
長いケーブルが不要となり、事故のない自動制御式の電
気防食法が可能となった。Furthermore, this cathodic protection method has another major feature. Since the current of the power transistor 5 used for current control is supplied from the galvanic anode 2, an external power source for the output transistor 5 is not necessary regardless of the magnitude of the corrosion protection current, and the base current (or gate It requires only a very small capacity power supply to drive the deviation amplification circuit that adjusts the voltage), and since it requires only a small amount of power, it is possible to operate this cathodic protection device for a long period of time even when it is driven by a battery, allowing continuous potential control. That's right. In this way, the power supply has a small capacity and long life, and the number of parts of the circuit is small as shown in the figure, so the entire device including the power supply for the dry battery can be made extremely small, and it has a watertight structure, and a galvanic anode in the soil or water. It can be installed close to the cable, and the long cable that has been the main cause of failure in the automatic control type anticorrosion method that uses an external rectification power source is no longer necessary, enabling an automatic control type cathodic protection method without accident. became.
【００１８】また、この電位制御装置（電気防食装置）
は簡単で安価に提供できるので、大きな構造物の防食に
多数の流電陽極が使用されても経済的に自動制御式の電
気防食法が適用でき、防食効果の一段の向上が期待され
る。Further, this potential control device (cathodic protection device)
Since it can be provided easily and inexpensively, even if a large number of galvanic anodes are used for the corrosion protection of a large structure, the economically controlled automatic corrosion protection method can be applied, and further improvement of the corrosion protection effect is expected.
【００１９】この電気防食法では、電子回路を用いるの
で、野外で作動中落雷や漏洩等のサージ電流でトランジ
スタ等が破壊する恐れがあり、この破壊で被防食体１と
流電陽極２との接続が断たれることになって防食作用が
停止する。これを防止するため、入力保護素子８、８′
等で回路の保護を図るが、さらに安全性を高めるため、
図１に示すように、出力トランジスタ５と並列に固定抵
抗９を付加して接続することもできる。すなわち、この
防食法において定常状態で流れるであろうと予想される
電流（通常は初期電流の５０％程度）を流し得るような
値の固定抵抗９をトランジスタ５と並列に被防食体１と
流電陽極２との間に接続することにより、もしトランジ
スタ５が破壊・断線しても最小限の防食電流は確保でき
るようにするものである。また、固定抵抗９がトランジ
スタと並列になるので、サージ電流が加わったとき、ト
ランジスタ内を流れるサージ電流をバイパスしてトラン
ジスタの保護にも効果がある。防食電流は通常被防食体
のエレクトロコーティング等の進行により初期電流の約
５０％程度まで低下するので、これを目安に抵抗値が決
定される。In this cathodic protection method, since an electronic circuit is used, there is a risk that a transistor or the like is destroyed by a surge current such as lightning strike or leakage during operation in the field. The connection will be broken and the anticorrosion effect will stop. In order to prevent this, the input protection elements 8 and 8 '
Etc. to protect the circuit, but to further enhance safety,
As shown in FIG. 1, a fixed resistor 9 may be added and connected in parallel with the output transistor 5. That is, in this anticorrosion method, a fixed resistor 9 having a value capable of passing a current expected to flow in a steady state (usually about 50% of the initial current) is provided in parallel with the transistor 5 and the anticorrosion body 1 and the galvanic current. By connecting the anode 5 to the anode 2, even if the transistor 5 is broken or disconnected, a minimum anticorrosive current can be secured. Further, since the fixed resistor 9 is in parallel with the transistor, when a surge current is applied, the surge current flowing in the transistor is bypassed, which is effective for protecting the transistor. Since the anticorrosion current usually decreases to about 50% of the initial current due to the progress of electrocoating of the object to be protected, the resistance value is determined by using this as a guide.
【００２０】このようにして防食を開始すると、定常時
の電流以上に流れる初期の大きな電流は自動的にトラン
ジスタ内を経由してバイパスされ、被防食体１の電位が
一定になるように制御される。時間の経過と共に、トラ
ンジスタ内のバイパス電流は次第に減少し、定常状態で
は抵抗のみで必要な電流の大部分が供給される。この時
期以前にトランジスタ関連の故障があっても、上記の最
低電流は供給され、一応の防食効果は確保される。定常
状態到達後は電位の変動も少なくなり、トランジスタ５
を通過する電流は僅かになり、トランジスタ５の破壊に
よる断線があっても固定抵抗でほぼ必要な電流が供給さ
れるので、被防食体の電位は目的の値から大きく外れる
ことはなく、一応の防食効果は期待できる。When the anticorrosion is started in this way, a large initial electric current that exceeds the steady-state electric current is automatically bypassed via the inside of the transistor, and the potential of the anticorrosion object 1 is controlled to be constant. It With time, the bypass current in the transistor gradually decreases, and in the steady state, the resistor alone supplies most of the required current. Even if there is a transistor-related failure before this period, the above-mentioned minimum current is supplied and a temporary anticorrosion effect is secured. After the steady state is reached, the fluctuation of the potential is reduced and the transistor 5
The current passing through the circuit becomes small, and even if there is a disconnection due to the destruction of the transistor 5, the fixed resistor supplies almost the required current, so the potential of the body to be protected does not greatly deviate from the target value, and Anticorrosion effect can be expected.
【００２１】なお、このように並列抵抗の挿入によりト
ランジスタ５が取扱う電流がかなり減少するので、トラ
ンジスタ５の入力駆動電流が小さくて済み、これは電圧
増幅器６の出力の減少すなわち電源の乾電池の寿命延長
にも貢献する。しかし、トランジスタ５に並列に固定抵
抗９を挿入することは装置の安全性の向上に役立つ一
方、防食電流の調節範囲を狭めることになるので、大幅
な電流変化が生じる場合には、この固定抵抗９は使用し
ないほうが好ましい。Since the current handled by the transistor 5 is considerably reduced by inserting the parallel resistance in this way, the input drive current of the transistor 5 can be made small, which means that the output of the voltage amplifier 6 is reduced, that is, the life of the dry battery of the power supply. Also contribute to extension. However, while inserting the fixed resistor 9 in parallel with the transistor 5 helps improve the safety of the device, it also narrows the adjustment range of the anticorrosion current. Therefore, when a large current change occurs, this fixed resistor 9 is used. It is preferable not to use 9.
【００２２】流電陽極２の電流制御用のパワートランジ
スタ５の電源は流電陽極２自体が分担するが、電圧増幅
器６を含む偏差制御回路を駆動するため小容量の別個の
電源が必要である。電圧増幅器の所要電力は極めて少な
くて済むので、乾電池で十分長期の稼働が可能である
が、水中の流電陽極に近接して設置されるときは、電池
の交換が困難になるので、さらに長寿命の電源の開発が
望まれる。このため、電気防食法の構成要素である流電
陽極のエネルギーを利用する自給式の電源を用いた。The power source of the power transistor 5 for controlling the current of the galvanic anode 2 is shared by the galvanic anode 2 itself, but a small-capacity separate power source is required to drive the deviation control circuit including the voltage amplifier 6. . Since the voltage amplifier requires very little power, it can be operated for a long time with a dry battery, but when it is installed close to a galvanic anode in water, it becomes difficult to replace the battery, so it is even longer. Development of a power source with a long life is desired. Therefore, a self-contained power source that uses the energy of the galvanic anode, which is a component of the cathodic protection method, was used.
【００２３】図２は、本発明の流電陽極方式定電位自動
制御式電気防食法に用いられる防食装置の他の例を示す
説明図である。この電気防食装置において、被防食体１
の他に補助陰極１０を流電陽極の近傍の環境中に設置
し、流電陽極２と補助陰極１０とにスイッチング方式の
ＤＣ・ＤＣコンバータ１１の入力端子を接続し、流電陽
極２と補助陰極１０との間に流れる電流を該コンバータ
１１でスイッチングして交流に変換・昇圧後整流して偏
差制御回路を駆動するのに十分な電圧と電流容量を有す
る直流電源を得て、電圧増幅器６や電位設定部７を駆動
するようにするものである。補助陰極１０は有効電位差
が大きく取れるように鋼、チタンやステンレス鋼等が望
ましい。このようにして商用交流は乾電池も必要としな
い（但し、図中の１２に示すように該コンバータ１１を
スタートさせ安定に連続作動させるためのバックアップ
用の小容量の二次電池は必要となる）自給式の電源で、
流電陽極２が消耗し尽くすまで本発明の電気防食法はメ
ンテナンスフリーに実施できる。なお、該コンバータ１
１は流電陽極２と被防食体１との間に接続して使用して
も、前記と同様に増圧した直流電源が得られる。FIG. 2 is an explanatory view showing another example of the anticorrosion device used in the galvanic anode type constant potential automatic control type anticorrosion method of the present invention. In this cathodic protection device, the body to be protected 1
In addition, the auxiliary cathode 10 is installed in the environment near the galvanic anode, and the input terminals of the switching type DC / DC converter 11 are connected to the galvanic anode 2 and the auxiliary cathode 10 to connect the galvanic anode 2 and the auxiliary. The converter 11 switches the current flowing between it and the cathode 10 to convert it into an alternating current, boosts it, and rectifies it to obtain a DC power supply having a voltage and current capacity sufficient to drive the deviation control circuit, and to obtain a voltage amplifier 6 The potential setting unit 7 is driven. The auxiliary cathode 10 is preferably made of steel, titanium, stainless steel, or the like so that a large effective potential difference can be obtained. In this way, commercial AC does not require a dry battery (however, as shown by 12 in the figure, a small-capacity secondary battery for backup for starting the converter 11 for stable and continuous operation is required). With a self-contained power supply,
The cathodic protection method of the present invention can be performed maintenance-free until the galvanic anode 2 is exhausted. The converter 1
Even if 1 is used by connecting it between the galvanic anode 2 and the body 1 to be protected, a boosted DC power source can be obtained in the same manner as described above.
【００２４】以上、説明してきたように、流電陽極を用
いる本発明の電気防食法の適用により、被防食体の電位
は、防食電流が如何に変動しようとも、流電陽極の陽極
電位より貴な範囲の任意の設定した値に自動制御され
る。従って、高張力鋼に対しては−９５０ｍＶ、チタン
には−７００ｍＶに維持すればそれらの水素脆化が防止
され、オーステナイトステンレス鋼には−４５０±５０
ｍＶに保持して隙間腐食が効果的に防止され、幅広い材
料についてそれぞれ安全に防食の保持ができる。As described above, by applying the cathodic protection method of the present invention using a galvanic anode, the potential of the corrosion-prevented material is higher than the anode potential of the galvanic anode, no matter how the corrosion current changes. It is automatically controlled to any set value within the specified range. Therefore, hydrogen embrittlement is prevented by maintaining -950 mV for high-strength steel and -700 mV for titanium, and -450 ± 50 for austenitic stainless steel.
By maintaining it at mV, crevice corrosion can be effectively prevented, and a wide range of materials can be safely kept in anticorrosion.
【００２５】[0025]
【実施例】以下、実施例に基づいて本発明を具体的に説
明する。EXAMPLES The present invention will be specifically described below based on examples.
【００２６】実施例１ 図１の説明図に基づいて設計した電気防食装置を用い、
ステンレス鋼製の水道水貯槽の防食を試験した。電流制
御用のトランジスタにはＰ型のパワートランジスタを、
電圧増幅器には利得１００ｄｂの演算増幅器をそれぞれ
１個使用し、電圧増幅器の電源には乾電池を使用した。
流電陽極にはマグネシウム陽極、照合電極には飽和カロ
メル電極をそれぞれ用いた。なお、被防食体の電位の設
定値は、−４５０ｍＶ（飽和カロメル電極基準）とした
が、トランジスタには並列固定抵抗は用いなかった。試
験期間中における電流の概略の変化と制御電位の安定性
を図３に示す。 Example 1 Using an anticorrosion device designed based on the explanatory view of FIG.
A stainless steel tap water reservoir was tested for corrosion protection. A P-type power transistor is used as the current control transistor.
One operational amplifier with a gain of 100 db was used for each voltage amplifier, and a dry battery was used for the power source of the voltage amplifier.
A magnesium anode was used as the galvanic anode, and a saturated calomel electrode was used as the reference electrode. The set value of the potential of the body to be protected was -450 mV (based on saturated calomel electrode), but the parallel fixed resistance was not used for the transistor. FIG. 3 shows the approximate change in current and the stability of the control potential during the test period.
【００２７】同図に示されるように、極く初期には大き
な電流が流れたが、直ぐ低下し、その後はほぼ一定の値
を維持した。一方、貯槽の自然電位は−０．２Ｖ程度で
あったが、防食の開始と同時に電位は−０．４５Ｖに保
持され、試験の間の制御電位の値は設定値の±５ｍＶの
範囲に調節されていた。また、防食状態は良好であっ
た。As shown in the figure, a large current flowed at the very beginning, but immediately decreased, and thereafter maintained a substantially constant value. On the other hand, the natural potential of the storage tank was about -0.2V, but the potential was held at -0.45V at the same time as the start of corrosion prevention, and the value of the control potential during the test was adjusted to within ± 5 mV of the set value. It had been. The anticorrosion condition was good.
【００２８】実施例２ 電位の偏差制御回路の電源の長寿命化を図るため、流電
陽極のエネルギーを利用する図２の説明図に基づいて設
計した電気防食装置を用いた。 Example 2 In order to prolong the life of the power source of the potential deviation control circuit, the cathodic protection device designed based on the explanatory view of FIG. 2 utilizing the energy of the galvanic anode was used.
【００２９】すなわち、図２の電気防食装置において、
水道水を入れたステンレス鋼製貯槽中に設置したマグネ
シウム合金陽極の近傍にステンレス鋼板を設け、それと
流電陽極とをフライバック方式のＤＣ・ＤＣコンバータ
の入力側を接続した。出力側には約９Ｖの直流電圧が発
生し、電圧増幅器１個の偏差制御回路を十分駆動する電
力が得られた。That is, in the cathodic protection device of FIG.
A stainless steel plate was provided in the vicinity of a magnesium alloy anode installed in a stainless steel storage tank containing tap water, and the galvanic anode was connected to the input side of a flyback DC / DC converter. A DC voltage of about 9V was generated on the output side, and sufficient power to drive the deviation control circuit with one voltage amplifier was obtained.
【００３０】[0030]
【発明の効果】以上、説明したように、本発明に係る電
気防食法によって、１種類の陽極電位しか持たない流電
陽極を用いながらも簡単な電位制御装置（電気防食装
置）の使用により被防食体を任意の適正な単位に常時維
持することができるので、過防食による塗膜の剥離やス
テンレス鋼の隙間腐食を防止し、あるいは高張力鋼やチ
タン等の水素吸収を防止する限界電位に保持してそれら
材料の水素脆化を防ぐ等、種々の材料について幅広く条
件に対応して完全防食を可能ならしめることができる。As described above, according to the cathodic protection method of the present invention, it is possible to use a simple potential control device (cathodic protection device) while using a galvanic anode having only one kind of anode potential. Since the anticorrosion body can be maintained in any appropriate unit at all times, it has a limit potential that prevents peeling of the coating film due to overcorrosion or crevice corrosion of stainless steel, or hydrogen absorption of high-tensile steel or titanium. It is possible to completely prevent corrosion by keeping a wide range of conditions for various materials, such as holding them to prevent hydrogen embrittlement of those materials.
【図１】 本発明の電気防食法に用いられる電気防食装
置の一例を示す説明図。FIG. 1 is an explanatory view showing an example of a cathodic protection device used in the cathodic protection method of the present invention.
【図２】 本発明の電気防食法に用いられる電気防食装
置の他の例を示す説明図。FIG. 2 is an explanatory view showing another example of the cathodic protection device used in the cathodic protection method of the present invention.
【図３】 実施例１に置ける電位および電流密度の経時
変化を示すグラフ。FIG. 3 is a graph showing changes with time in potential and current density in Example 1.
１：被防食体、２：流電陽極、３：照合電極、４：環
境、５：トランジスタ、６：電圧増幅器、７：電位設定
部、８、８′：電子回路の入力保護素子、９：固定抵
抗、１０：補助陰極、１１：ＤＣ・ＤＣコンバータ、１
２：バックアップ電池、Ｅｐ：被防食体の電位、Ｅａ：
流電陽極の電位、Ｅｓ：設定電位。1: Corrosion protection body, 2: Galvanic anode, 3: Reference electrode, 4: Environment, 5: Transistor, 6: Voltage amplifier, 7: Potential setting section, 8 and 8 ': Input protection element of electronic circuit, 9: Fixed resistance, 10: auxiliary cathode, 11: DC / DC converter, 1
2: backup battery, Ep: potential of anticorrosion object, Ea:
Galvanic anode potential, Es: set potential.
Claims (5)
クタとエミッタまたは電界効果型パワートランジスタの
ドレインとソースにそれぞれ流電陽極と被防食体とを接
続し、照合電極で測定した被防食体の電位と設定電位と
の差電圧を該トランジスタとは別個の電源で駆動される
電圧増幅器で増幅し、該電圧増幅器の出力をもって該ト
ランジスタのコレクタ電流またはドレイン電流を調節す
ることにより被防食体の電位を制御し、設定電位に保持
することを特徴とする流電陽極方式定電位自動制御式電
気防食法。1. A galvanic anode and an anticorrosion body are connected to a collector and an emitter of a bipolar power transistor or a drain and a source of a field effect power transistor, respectively, and the potential of the anticorrosion measured by a reference electrode and a set potential. A voltage difference between the transistor and the transistor is amplified by a voltage amplifier driven by a power source separate from the transistor, and the output of the voltage amplifier is used to adjust the collector current or drain current of the transistor to control the potential of the body to be protected, A galvanic anode type constant potential automatic control type cathodic protection method, which is characterized by holding at a set potential.
流電陽極との間に固有抵抗を接続されている請求項１に
記載の電気防食法。2. The galvanic protection method according to claim 1, wherein a specific resistance is connected in parallel with the transistor between the body to be protected and the galvanic anode.
電位を測定する照合電極の３電極よりなり、該流電陽極
と該被防食体に接続されるパワートランジスタ、被防食
体の目的とする電位の値を設定する電位設定部、および
測定される該被防食体の電位と設定電圧の差電圧を増幅
し、もって該トランジスタを制御する電圧増幅器を有
し、該電圧増幅器および電位設定部を駆動し、該トラン
ジスタとは異なる電源を備えることを特徴とする定電位
自動制御式電気防食装置。3. A galvanic anode, an anticorrosion body, and a reference electrode for measuring the potential of the anticorrosion body, which are three electrodes, and are connected to the galvanic anode and the anticorrosion body. A potential setting unit that sets a value of a target potential, and a voltage amplifier that amplifies a difference voltage between the measured potential of the corrosion-prevented object and the set voltage and thus controls the transistor, the voltage amplifier and the potential A constant potential automatic control type anticorrosion device, which drives a setting unit and is provided with a power source different from the transistor.
流電陽極との間に固有抵抗が設けられている請求項３に
記載の電気防食装置。4. The cathodic protection device according to claim 3, wherein a specific resistance is provided in parallel with the transistor between the object to be protected and the galvanic anode.
動する電源が、流電陽極と該流電陽極の近傍に設けられ
た補助陰極、あるいは該流電陽極と該被防食体とに接続
されるスイッチング方式のＤＣ・ＤＣコンバータにより
増圧された直流電源である請求項３に記載の電気防食装
置。5. A power source for driving the voltage amplifier and the potential setting unit is connected to a galvanic anode and an auxiliary cathode provided in the vicinity of the galvanic anode, or the galvanic anode and the corrosion-protected body. The cathodic protection device according to claim 3, wherein the cathodic protection device is a DC power source boosted by a switching type DC / DC converter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06018847A JP3135776B2 (en) | 1994-01-20 | 1994-01-20 | Galvanic anode method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06018847A JP3135776B2 (en) | 1994-01-20 | 1994-01-20 | Galvanic anode method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07207474A true JPH07207474A (en) | 1995-08-08 |
| JP3135776B2 JP3135776B2 (en) | 2001-02-19 |
Family
ID=11982954
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06018847A Expired - Fee Related JP3135776B2 (en) | 1994-01-20 | 1994-01-20 | Galvanic anode method |
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| Country | Link |
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| JP (1) | JP3135776B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101260526A (en) * | 2008-03-10 | 2008-09-10 | 中国人民解放军海军装备技术研究所 | Composite electric potential coupling corrosion control technique |
| CN104674229A (en) * | 2015-03-06 | 2015-06-03 | 中国石化管道储运有限公司 | Intelligent remote monitoring and regulating system for cathode protection of underground pipelines |
| KR20170030849A (en) | 2015-09-10 | 2017-03-20 | 단국대학교 천안캠퍼스 산학협력단 | System and method for controlling corrosion-enabled power supply and light emitting apparatus using the same |
| CN107326367A (en) * | 2017-07-10 | 2017-11-07 | 中海石油(中国)有限公司 | In-service offshore platform tension type impressed current cathodic protection and monitoring device and method |
| JP2018125934A (en) * | 2017-01-31 | 2018-08-09 | ホシデン株式会社 | Non-contact power supply device |
-
1994
- 1994-01-20 JP JP06018847A patent/JP3135776B2/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101260526A (en) * | 2008-03-10 | 2008-09-10 | 中国人民解放军海军装备技术研究所 | Composite electric potential coupling corrosion control technique |
| CN104674229A (en) * | 2015-03-06 | 2015-06-03 | 中国石化管道储运有限公司 | Intelligent remote monitoring and regulating system for cathode protection of underground pipelines |
| KR20170030849A (en) | 2015-09-10 | 2017-03-20 | 단국대학교 천안캠퍼스 산학협력단 | System and method for controlling corrosion-enabled power supply and light emitting apparatus using the same |
| JP2018125934A (en) * | 2017-01-31 | 2018-08-09 | ホシデン株式会社 | Non-contact power supply device |
| CN107326367A (en) * | 2017-07-10 | 2017-11-07 | 中海石油(中国)有限公司 | In-service offshore platform tension type impressed current cathodic protection and monitoring device and method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3135776B2 (en) | 2001-02-19 |
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