WO2015083580A1 - 電気防食システム - Google Patents

電気防食システム Download PDF

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Publication number
WO2015083580A1
WO2015083580A1 PCT/JP2014/081073 JP2014081073W WO2015083580A1 WO 2015083580 A1 WO2015083580 A1 WO 2015083580A1 JP 2014081073 W JP2014081073 W JP 2014081073W WO 2015083580 A1 WO2015083580 A1 WO 2015083580A1
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WIPO (PCT)
Prior art keywords
anode electrode
cathodic protection
protection system
pipe
seawater
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.)
Ceased
Application number
PCT/JP2014/081073
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English (en)
French (fr)
Japanese (ja)
Inventor
大橋　健也
将宏 伊藤
千葉　由昌
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Hitachi Ltd
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Hitachi Ltd
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Publication date
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Priority to SG11201604516VA priority Critical patent/SG11201604516VA/en
Publication of WO2015083580A1 publication Critical patent/WO2015083580A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/04—Feed pretreatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/025—Reverse osmosis; Hyperfiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/10—Accessories; Auxiliary operations
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
    • C23F13/16—Electrodes characterised by the combination of the structure and the material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
    • C23F13/18—Means for supporting electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/04—Specific process operations in the feed stream; Feed pretreatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/26—Further operations combined with membrane separation processes
    • B01D2311/2649—Filtration
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08—Seawater, e.g. for desalination
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/08—Corrosion inhibition
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F2213/00—Aspects of inhibiting corrosion of metals by anodic or cathodic protection
    • C23F2213/30—Anodic or cathodic protection specially adapted for a specific object
    • C23F2213/32—Pipes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

Definitions

  • the present invention relates to an electro-corrosion protection system for metal pipes for water flow, and more particularly, to an electro-corrosion protection system of an external power source suitable for anti-corrosion of metal pipes for transferring seawater.
  • water includes “seawater”.
  • Seawater pumps are used not only for pumping seawater from the sea area and cooling the plant, but also as an injection system for extracting oil components by injecting seawater in oil fields into the oil bed.
  • development of a technique for desalinating seawater using a seawater desalination apparatus and using it for industrial use, agricultural use, daily beverage use, and the like is underway.
  • large-scale seawater desalination equipment using RO membranes requires a lot of metal piping, which affects the life of RO membranes and is reliable against corrosion of metal piping materials. (Corrosion resistance) is important.
  • Stainless steel is usually used as the metal piping material until the seawater is pumped and reaches the RO facility. What is widely used as a seawater-resistant material in pumps and seawater desalination equipment pipes is not SUS304, but SUS316 steel, which has the same austenitic steel and has improved corrosion resistance in seawater by addition of Mo. Duplex stainless steel is sometimes used in bell mouths and casings of seawater pumps. Further, in the seawater desalination system, a duplex stainless steel, for example, a highly corrosion resistant material such as S32750 is used for the piping that becomes higher pressure to perform reverse osmosis with the RO membrane.
  • a high-strength, high-corrosion-resistant material such as S32750 is also used for a pipe of a waste liquid portion concentrated in salt called downstream brine.
  • high-grade engineering plastics may be used in some cases.
  • metal piping materials for seawater pumps and seawater desalination devices
  • highly corrosion-resistant metals for the metal piping materials.
  • a super duplex stainless steel such as S32750 may be used in metal piping or brine that is at a higher pressure to perform reverse osmosis with an RO membrane.
  • using such an expensive metal is not preferable in terms of cost.
  • a method for preventing corrosion of the metal piping material a method using a sacrificial anode or a method based on cathodic protection using a cathode electrode can be considered in addition to using the above-described highly corrosion-resistant metal.
  • an anticorrosion method using an insoluble cathode electrode such as Pt (platinum) has been proposed. These methods are described, for example, in JP-A-11-092981 and JP-A-61-067782.
  • Patent Document 1 and Patent Document 2 uses an expensive insoluble platinum (Pt) electrode as an electrode, which is not preferable from the viewpoint of cost reduction.
  • one embodiment of the present invention provides An anti-corrosion system for suppressing corrosion of metal piping for water flow, It is sandwiched between two insulating gaskets interposed between the flanges connecting the joints of the pipe so as to be partially covered, and the part is exposed from the gasket so that water is contained inside the metal pipe.
  • An anode electrode for anticorrosion that constitutes a water contact surface in contact with A terminal for an anode electrode at least partially sandwiched by the gasket;
  • a direct current power source that is connected to the anode electrode and the pipe via the terminal and electric wiring, and flows a corrosion-proof current to a water passage portion of the pipe;
  • a first sealing member that seals between the flange portion and the gasket;
  • a cathodic protection system comprising: a second seal member that seals between the gasket and the terminal or between the anode electrode and the terminal.
  • a metal pipe in order to achieve the above object, a metal pipe, a rotary shaft provided inside the metal pipe, an impeller provided at a tip of the rotary shaft, and a motor for rotationally driving the rotary shaft and the impeller.
  • a seawater pump for pumping the water flow brought about by the above and guiding the inside of the metal pipe, Provided is a seawater pump, wherein the metal pipe is provided with the cathodic protection system.
  • An intake well for storing the taken-in seawater a filtered seawater tank for storing the seawater from the intake well that passes through the filter and filtered by the filter, and the filtered seawater from the filtered seawater tank
  • a power recovery turbine that recovers the salt-concentrated water separated by the reverse osmosis membrane module and discharges it to a concentrated water pipe;
  • the seawater desalination apparatus in which the intake well, the filter, the filtered seawater tank, the security filter, the reverse osmosis membrane module, the production water tank, the high pressure pump, and the power recovery turbine are connected by a metal pipe.
  • the metal pipe includes the
  • an anticorrosion system capable of realizing an improvement in corrosion resistance of metal piping materials such as a seawater pump and a seawater desalination apparatus at low cost and high efficiency.
  • a low-cost seawater pump and seawater desalination apparatus can be provided using the cathodic protection system according to the present invention.
  • FIG. 1st Embodiment of the cathodic protection system which concerns on this invention. It is a principle diagram of the cathodic protection system according to the present invention shown in FIG. It is a cross-sectional schematic diagram which shows an example of a deformation
  • the cathodic protection system according to the present invention can optionally include the following aspects.
  • the first and second sealing members are O-rings.
  • the anode electrode is ring-shaped, and the two gaskets are overlapped to form an annular groove covering the outer periphery and both side surfaces of the anode electrode on the inner periphery side, and the anode electrode The inner circumference forms the water contact surface.
  • the anode electrode is at least one of carbon, graphite, and ferrite.
  • the first seal member is provided between the first O-ring in the circumferential direction of the pipe disposed between one pipe and the corresponding gasket, and between the other pipe and the corresponding gasket.
  • the second seal member is composed of an O-ring in the terminal circumferential direction attached to the outer periphery of the terminal.
  • the elastic modulus increases in the order of the seal member, the gasket, the anode electrode, and the terminal.
  • the anode electrode is a carbon sheet.
  • the cross-sectional shape of the anode electrode is a triangle.
  • An organic adhesive is provided between the anode electrode and the gasket.
  • the gasket is a spiral insulating gasket, and the spiral insulating gasket also serves as the seal member.
  • the DC power source any one of a primary battery, a secondary battery, and a solar battery is used, the applied voltage is set to 1 V or more and less than 2 V, and the anode electrode is connected to the positive side of the DC power source.
  • An ammeter is provided between the anode electrode and the DC power supply or between the metal pipe and the DC power supply.
  • the water permeability of the anode electrode is 10% or less.
  • the DC power supply is provided outside the metal pipe.
  • FIG. 1 is a schematic cross-sectional view showing a first embodiment of the cathodic protection system according to the present invention.
  • the cathodic protection system 100 of the present invention includes two insulating gaskets 2 a and 2 b interposed between flange portions connecting joint portions of a metal pipe 6 that transfers seawater (not shown). And at least a part of the anode electrode 7 for anticorrosion, which is sandwiched so as to be covered by a part, and partly exposed from the gaskets 2a and 2b and constituting a water contact surface in contact with water inside the metal pipe 6.
  • the DC power source 9 the first seal member 4 (4 a and 4 b) that seals between the flange portion of the metal pipe 6 and the gaskets 2 a and 2 b, and the gap between the gaskets 2 a and 2 b and the terminal 1 are sealed. It comprises a second seal member 5, a.
  • the second sealing member has a mode of sealing between the anode 2 and the terminal 1 as well as a mode of sealing between the gaskets 2a and 2b and the terminal 1 as shown in FIG. Also good. The latter aspect will be described in detail later.
  • the gaskets 2a and 2b and the anode electrode 7 are both annular, and the two gaskets 2a and 2b are overlapped to form an annular groove covering the outer periphery and both side surfaces of the anode electrode 7 on the inner periphery thereof.
  • the inner periphery of the anode electrode 7 constitutes the water contact surface.
  • the shape and material of the first seal member 4 and the second seal member 5 are not particularly limited, but, for example, a rubber O-ring is suitable.
  • the first seal member 4 is disposed between the first O-ring 4a in the circumferential direction of the pipe disposed between one pipe and the corresponding gasket, and between the other pipe and the corresponding gasket.
  • the second O-ring 4b in the circumferential direction of the pipe is formed, and the second seal member is composed of an O-ring in the circumferential direction of the terminal attached to the outer periphery of the terminal 1.
  • a terminal 1 ′ is also provided on the metal pipe side, and is connected to the DC power source 9 through the electric wiring 10.
  • FIG. 2 is a principle diagram of the cathodic protection system according to the present invention shown in FIG.
  • the metal pipe 6 is connected to the negative side of the DC power supply 9.
  • the anode electrode 7 is connected to the positive side of the DC power supply 9, and current is supplied from the DC power supply 9 to the anode electrode 7.
  • electrons are supplied to the surface of the metal pipe 6 in contact with seawater, so that cations (positive ions) in the seawater are attracted, and the metal pipe 6 has its own metal cation by a corrosion reaction. Is suppressed from being released. Corrosion of the metal piping of the seawater pump or seawater desalination apparatus can be suppressed by using such means of cathodic protection.
  • the anode electrode 7 is held by the gaskets 2 a and 2 b so that at least a part of the anode electrode 7 is in contact with seawater flowing inside the metal pipe 6. Further, the anode electrode 7 applies a negative potential to the metal pipe 6 so that the metal pipe 6 has a lower potential than the natural immersion potential of the pipe material itself.
  • the material of the anode electrode 7 is required to have electrical continuity.
  • any of carbon, graphite, and ferrite is preferable from the viewpoint of cost.
  • the material of the anode electrode 7 is such that the metal eluted by the electrochemical dissolution by the electrical connection with the metal pipe 6 does not cause the RO membrane function of the seawater desalination apparatus to deteriorate. Preferably there is.
  • the water treatment agent used for the RO membrane and the metal eluted from the anode electrode combine to form a metal compound (for example, oxide, hydroxide, sulfate, Chloride), which are deposited on the surface of the RO membrane and cause clogging of the RO membrane, which may reduce the desalination performance.
  • a metal compound for example, oxide, hydroxide, sulfate, Chloride
  • carbon is more preferable as a material of the anode electrode 7 applied to the seawater desalination apparatus.
  • the seawater pump does not have the above-mentioned problem relating to the elution of the anode electrode, so the material of the anode electrode 7 is not particularly limited.
  • Platinum which is a non-soluble material, is often used for cathodic protection as an anode electrode.
  • it is an expensive material, and as an anticorrosion device for a seawater desalination device, it has a salt concentration effect if it adheres to the surface of the RO membrane. Unsuitable for lowering.
  • zinc or aluminum which is a base metal than the piping material, is effective as a sacrificial anode, but if it adheres to the surface of the RO membrane, it is unsuitable for reducing the salt concentration effect.
  • the potential of the metal piping material 6 becomes base, and cations are easily adsorbed. For this reason, the effect which catches the ion or ionic cluster substance which has the positive charge which brings the RO functional fall to the metal piping material 6 can be expected.
  • the present inventors have also confirmed the effect of suppressing the adhesion of bacteria that cause microbial corrosion.
  • the water permeability of the anode electrode 7 is preferably 10% or less.
  • the amount of thickness reduction becomes larger than when expensive platinum or the like is used.
  • the gaskets 2 a and 2 b are deformed, and there is a possibility that a gap is formed between the two gaskets 2 a and 2 b so that seawater flows out of the metal pipe 6.
  • the first seal member 4 and the second seal member 5 are used to suppress the deformation of the gaskets 2a and 2b due to the thinning of the anode electrode 7, thereby preventing seawater leakage. Below, the effect of the 1st sealing member 4 and the 2nd sealing member 5 is demonstrated.
  • FIG. 3 is a schematic cross-sectional view showing an example of deformation of the gasket when the anode electrode is thinned and the gasket is deformed. Note that the terminals are omitted.
  • the dotted line portion shows the anode electrode 7 and the gasket 2 before thinning
  • the solid line portion shows the anode electrode 7 'and the gasket 2' after thinning.
  • the anode electrode 7 gradually becomes thin when a current is supplied, and has a triangular shape.
  • the gasket is deformed as 2 '.
  • Seawater flowing in the metal pipe 6 is 10 atm or more, and when the gasket 2 is deformed as shown in FIG.
  • the seawater flowing in the metal pipe 6 leaks to the outside.
  • the deformation of the gasket 2 can be prevented, and the seawater flowing in the metal pipe 6 can be prevented. Can be prevented from leaking to the outside, and the efficiency of cathodic protection can be improved.
  • the first seal member 4 is connected to the flange 8. Since the seawater flow path that may occur in the gap between the gaskets 2 is blocked, leakage is suppressed. Further, the second seal member 5 suppresses leakage until the electrode of the anode electrode 7 disappears and corrosion of the lead of the terminal 1 proceeds.
  • the first seal member 4 and the second seal member 5 suppress the deformation of the gasket 2 due to the thinning of the anode electrode 7, the first seal member 4 and the second seal member 5 are inexpensive to the anode electrode 7. When the material is applied, the present invention can exert a greater effect.
  • the first seal member 4 and the second seal member 5, the gaskets 2a and 2b, the anode electrode 7, and the terminals 1 and 1 ' are in this order, and the Young against the mechanical action in the compression direction of the material. It is preferable to select the material so that the rate is high. By doing so, it is possible to remarkably suppress the reduction of the gasket sealing effect caused by the thinning that occurs with the passage of time of the anode electrode 7.
  • Table 1 shows the components of the cathodic protection system and preferred Young's modulus.
  • the anode electrode 7 is provided on the gaskets 2a and 2b, and the gaskets 2a and 2b are fixed by bolts that fix the flange portion of the metal pipe 6 (not shown).
  • the metal piping 6 can be electrically protected without obstructing the flow of seawater in the metal piping 6.
  • a corrosion phenomenon depending on the salt concentration occurs with the passage of time, and in particular, the flange part that is a pipe joint part and the surface texture and surface roughness are non-uniform. The corrosion rate increases at the weld.
  • the DC power supply 9 for generating a potential difference between the metal pipe 6 and the anode electrode 7 is not particularly limited, and may be any of a primary battery such as a dry battery, a secondary battery such as a lead battery or a lithium battery, a DC power supply, or a solar battery. Good. It is preferable that a potential difference of 1 V or more and less than 2 V can be applied. Since the natural electrode potential of the anode electrode 7 (carbon, graphite or ferrite) described above is +0.5 V and the natural electrode potential of the metal pipe 6 (stainless steel) is ⁇ 0.5 V, an anode reaction occurs. The minimum applied potential applied to the metal pipe 6 is 1V.
  • the ammeter 11 may be arranged in series with the DC power source 9. As the ammeter 11, an ammeter having an internal circuit with low resistance is used. The current value at this time is arbitrary, but 10 ⁇ A or more is desirable.
  • the range of the cathode that can have a potential difference is usually known as the Wagner length, which depends on the shape of the cathode, the flow rate of seawater, electrical conductivity, and temperature, but reaches several meters or more.
  • the Wagner length As described above, 1 V or more is suitable as the potential, and if it exceeds 2 V, hydrogen is generated by electrolysis of water, so that the potential application for increasing the Wagner length is limited.
  • the metal pipe 6 is not particularly limited, but stainless steel is preferable. Stainless steel is preferably SUS316L, S32101, or the like from the viewpoint of cost.
  • FIG. 4 is a schematic sectional view showing a second embodiment of the cathodic protection system according to the present invention.
  • FIG. 4 only half of the gaskets 401a and 401b, the anode electrode 402, the terminal 403, the first seal members 404a and 404b, and the second seal member 405 are shown, and the metal pipe, the terminal connected to the metal pipe, and the metal A direct current power source connected to each of the pipe and the anode electrode via electric wiring is omitted.
  • the second sealing member 405 seals between the anode electrode 402 and the terminal 403, and the shape of the anode electrode 402 is a portion different from that of the first embodiment.
  • the cross-sectional shape of the anode electrode 402 is triangular.
  • the anode current decreases as the thickness decreases with the increase of the corrosion prevention time. That is, by measuring (monitoring) the change in current over time using an electrode of this shape, it is possible to know how the anode electrode is consumed.
  • the anode electrode 402 continues its anticorrosion function, the anode electrode 402 functions as an anode, and the electrode material is eluted by the anode reaction.
  • the anode electrode 402 having a triangular cross section is thinned along with the elution, but since the thickness decreases from the bottom of the triangular cross section of the anode electrode 402 toward the apex, the bottom of the triangle gradually decreases. As a result, the water-saving area will decrease for a while. Therefore, even if the current density per unit area is the same, the anode current determined by the product of the water contact area and the current density decreases. This makes it possible to monitor the consumption of the anode electrode from changes in the anode current. Since other configurations are the same as those of the first embodiment, description thereof is omitted.
  • FIG. 5 is a schematic sectional view showing a third embodiment of the cathodic protection system according to the present invention.
  • FIG. 5 only half of the gaskets 501a and 501b, the anode electrode 502, the terminal 503, the first seal members 504a and 504b, and the second seal member 505 are shown, and the metal pipe, the terminal connected to the metal pipe, and the metal A direct current power source connected to each of the pipe and the anode electrode via electric wiring is omitted.
  • the second seal member 505 seals between the anode electrode 502 and the terminal 503, and an organic adhesive 506 is provided between the anode electrode 502 and the gaskets 501a and 501b.
  • organic adhesive there is no particular limitation on the organic adhesive, and for example, an epoxy adhesive can be used. Since other configurations are the same as those of the first embodiment, description thereof is omitted.
  • FIG. 6 is a schematic sectional view showing a fourth embodiment of the cathodic protection system according to the present invention.
  • FIG. 6 shows only half of the gasket 601, the anode electrode 602, and the terminal 603, with respect to the metal pipe, the terminal connected to the metal pipe, and the DC power source connected to each of the metal pipe and the anode electrode via electric wiring. Is omitted.
  • the gasket 601 is not an annular gasket but a spiral gasket.
  • the anode electrode 602 is covered with the spiral insulating gasket 601 at the center, and even if the anode electrode 602 is thinned, the sealing performance of the gasket 601 is maintained. That is, in this embodiment, the spiral gasket serves as the sealing member.
  • the spiral gasket has higher pressure resistance than the above-described annular gasket. Since other configurations are the same as those of the first embodiment, description thereof is omitted.
  • FIG. 7 is a schematic cross-sectional view showing an example of a seawater pump to which the cathodic protection system according to the present invention is applied.
  • a column pipe 201, a casing 202, a casing liner 203, and a bell mouth casing 204 are installed on the outer peripheral side of the seawater pump 200 as main members of the seawater pump 200. It is connected to.
  • a rotating shaft 206 is disposed on the axial center side of the seawater pump inside the column pipe 201, casing 202, casing liner 203, and bell mouth casing 204, and an impeller (impeller) is disposed on the distal end side of the rotating shaft 206. ) 208 is provided.
  • the seawater pump is provided with a motor for rotationally driving the rotary shaft 206 and the impeller 208, and the water flow produced by the rotary shaft 206 and the impeller 208 driven by the motor is shown in FIG. 7 becomes a water stream that moves to the top of the page, and is pumped.
  • the anode electrode 103 was disposed on the outer surface of the column pipe 201, and was fixed through the insulating sheet 111 while being electrically connected to the column pipe 201 by the conductive fixture 104.
  • An ammeter 112 is disposed on the side surface of the anode electrode 103.
  • the ammeter 112 is connected to the DC power supply device 113 by a cable 115.
  • the cable 115 has functions of signal transmission / reception and power supply.
  • the anode electrode 103 and the DC power supply unit 113 are shown large for easy viewing, but it is needless to say that the size is not limited.
  • the anode electrode 103 was installed via a flange structure so as to be in contact with seawater flowing on the inner surface of the column pipe 201 (not shown). At this time, the anode electrode 103 was disposed on the flange surface of the column pipe 201 for the purpose of not affecting the flow of water in the pump and for preventing the anode electrode 103 from falling off. In this case, the column pipe 201 and the anode electrode 103 were insulated.
  • FIG. 8 is a schematic cross-sectional view showing an example of a seawater desalination apparatus to which the cathodic protection system according to the present invention is applied.
  • the seawater desalination apparatus includes a seawater intake pump 300, a water intake well 301 for storing seawater, a two-layer filter 302, a filtered seawater tank 303, a safety filter 304, a high pressure pump 305, and a reverse osmosis membrane module.
  • 306 a power recovery turbine 307, a production water tank 308, a concentrated water pipe 309, and pipes 310, 311 and 312 are provided.
  • pumps 313 are provided at various locations for transferring seawater.
  • the cathodic protection system of the present invention is applied to each. Further, the high-pressure pump 305 and the pump 313 are applied with the cathodic protection system of the present invention on the inner surface in contact with seawater.
  • Metal piping is used in the piping section downstream from the high-pressure pump, and seawater flows at an internal pressure of 10 atmospheres or more.
  • corrosion phenomena that depend on the salt concentration occur over time, especially in the flanges that are pipe joints and in the welds where the surface texture and surface roughness are uneven, the corrosion rate is high. May develop.
  • the cathodic protection system of the present invention is suitable for metal piping.
  • RO membrane degradation reverse osmosis membrane module degradation
  • the cathodic protection system according to the present invention (Example 1) had no leak, and the leak test evaluation passed. Leakage also occurred in the anticorrosion system (Reference Examples 1 and 2) in which one of the seal members was omitted, and the leak test evaluation failed. Moreover, the comparative example 1 which abbreviate
  • Example 2 is a case where the cathodic protection system of the first embodiment of the present invention is used, and Comparative Example 2 is a result of simple immersion without using the cathodic protection according to the present invention.
  • the corrosion amount of Comparative Example 2 after 1000 hours is 8 times or more of the corrosion amount of Example 2, and it is confirmed that the corrosion of the metal pipe is remarkably suppressed by the cathodic protection system of the present invention. It was.
  • Example 3 is a case where the cathodic protection system of the first embodiment of the present invention is used, and Comparative Example 3 is a result of simple immersion without using the cathodic protection according to the present invention.
  • the corrosion amount of Comparative Example 3 after 1000 hours is more than five times the corrosion amount of Example 3, and it was confirmed that the corrosion of the metal piping is remarkably suppressed by the cathodic protection system of the present invention. It was.
  • Example 4 is a case where the cathodic protection system of the first embodiment of the present invention is used, and Comparative Example 4 is a result of simple immersion without using the cathodic protection according to the present invention.
  • the corrosion amount of Comparative Example 4 after 1000 hours is more than five times the corrosion amount of Example 4, and it is confirmed that the corrosion of the metal pipe is remarkably suppressed by the cathodic protection system of the present invention. It was.
  • an anticorrosion system capable of realizing an improvement in corrosion resistance of metal piping materials such as a seawater pump and a seawater desalination apparatus at low cost and high efficiency. And it was shown that a low-cost seawater pump and a seawater desalination apparatus can be provided using the cathodic protection system according to the present invention.
  • the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed.
  • the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described.
  • a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment.
  • Seawater pump 201 ... Column pipe, 202 ... Casing, 203 ... Casing liner, 204 ... Bellmouth casing, 205 ... Flange, 206 ... Rotating shaft, 208 ... Impeller (impeller), DESCRIPTION OF SYMBOLS 300 ... Intake pump, 301 ... Intake well, 302 ... Double layer filter, 303 ... Filtration seawater tank, 304 ... Security filter, 305 ... High pressure pump, 306 ... Reverse osmosis membrane module, 307 ... Power recovery turbine, 308 ... Production tank 309 ... concentrated water piping, 310, 311, 312 ... piping, 313 ... pump.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Nanotechnology (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Prevention Of Electric Corrosion (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
PCT/JP2014/081073 2013-12-04 2014-11-25 電気防食システム Ceased WO2015083580A1 (ja)

Priority Applications (1)

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SG11201604516VA SG11201604516VA (en) 2013-12-04 2014-11-25 Impressed current protect system

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JP2013-250698 2013-12-04
JP2013250698 2013-12-04

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017057464A (ja) * 2015-09-17 2017-03-23 株式会社日立製作所 電気防食システム及びそれを備えた海水淡水化プラント
CN108176228A (zh) * 2018-03-02 2018-06-19 秦皇岛天秦装备制造股份有限公司 一种防混合反渗透膜壳

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6766004B2 (ja) * 2017-04-06 2020-10-07 株式会社日立製作所 電気防食システム及びそれを備えた海水淡水化プラント

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4859714U (enExample) * 1971-11-11 1973-07-30
JPH1150278A (ja) * 1997-08-01 1999-02-23 Hitachi Zosen Tomioka Kikai Kk 配管電子防錆用電極
JPH1192981A (ja) * 1997-09-12 1999-04-06 Mitsubishi Materials Corp 配管フランジ間の隙間腐食に対する電気防食構造
WO2013179858A1 (ja) * 2012-05-28 2013-12-05 株式会社日立製作所 腐食抑制装置及びそれを備えた海水淡水化装置並びにポンプ装置
WO2014002814A1 (ja) * 2012-06-27 2014-01-03 株式会社日立製作所 海水淡水化装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4859714U (enExample) * 1971-11-11 1973-07-30
JPH1150278A (ja) * 1997-08-01 1999-02-23 Hitachi Zosen Tomioka Kikai Kk 配管電子防錆用電極
JPH1192981A (ja) * 1997-09-12 1999-04-06 Mitsubishi Materials Corp 配管フランジ間の隙間腐食に対する電気防食構造
WO2013179858A1 (ja) * 2012-05-28 2013-12-05 株式会社日立製作所 腐食抑制装置及びそれを備えた海水淡水化装置並びにポンプ装置
WO2014002814A1 (ja) * 2012-06-27 2014-01-03 株式会社日立製作所 海水淡水化装置

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017057464A (ja) * 2015-09-17 2017-03-23 株式会社日立製作所 電気防食システム及びそれを備えた海水淡水化プラント
CN108176228A (zh) * 2018-03-02 2018-06-19 秦皇岛天秦装备制造股份有限公司 一种防混合反渗透膜壳

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