CN117071019A - High-temperature oxidation resistant lifting method for main valve rod of in-service steam turbine - Google Patents
High-temperature oxidation resistant lifting method for main valve rod of in-service steam turbine Download PDFInfo
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- CN117071019A CN117071019A CN202311061838.7A CN202311061838A CN117071019A CN 117071019 A CN117071019 A CN 117071019A CN 202311061838 A CN202311061838 A CN 202311061838A CN 117071019 A CN117071019 A CN 117071019A
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- 230000003647 oxidation Effects 0.000 title claims abstract description 41
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000005269 aluminizing Methods 0.000 claims abstract description 30
- 238000004140 cleaning Methods 0.000 claims abstract description 30
- 238000009713 electroplating Methods 0.000 claims abstract description 17
- 239000011248 coating agent Substances 0.000 claims abstract description 15
- 238000000576 coating method Methods 0.000 claims abstract description 15
- 150000007524 organic acids Chemical class 0.000 claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000005498 polishing Methods 0.000 claims abstract description 11
- 230000009467 reduction Effects 0.000 claims abstract description 11
- 239000000956 alloy Substances 0.000 claims abstract description 9
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 8
- 238000005406 washing Methods 0.000 claims abstract description 8
- 229910003310 Ni-Al Inorganic materials 0.000 claims abstract description 7
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 239000012459 cleaning agent Substances 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 8
- 238000005260 corrosion Methods 0.000 claims description 7
- 230000007797 corrosion Effects 0.000 claims description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 6
- AEMRFAOFKBGASW-UHFFFAOYSA-N Glycolic acid Chemical compound OCC(O)=O AEMRFAOFKBGASW-UHFFFAOYSA-N 0.000 claims description 6
- 239000003638 chemical reducing agent Substances 0.000 claims description 6
- 239000003112 inhibitor Substances 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 4
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 3
- 229910021529 ammonia Inorganic materials 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 3
- 238000005496 tempering Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 abstract description 6
- 238000010297 mechanical methods and process Methods 0.000 abstract description 4
- 238000007747 plating Methods 0.000 abstract description 4
- 238000001035 drying Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 11
- 230000008569 process Effects 0.000 description 6
- 239000000565 sealant Substances 0.000 description 5
- 230000000903 blocking effect Effects 0.000 description 4
- 238000011010 flushing procedure Methods 0.000 description 3
- 244000137852 Petrea volubilis Species 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910000943 NiAl Inorganic materials 0.000 description 1
- NPXOKRUENSOPAO-UHFFFAOYSA-N Raney nickel Chemical compound [Al].[Ni] NPXOKRUENSOPAO-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 238000010285 flame spraying Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000005488 sandblasting Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
-
- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/18—Solid state diffusion of only metal elements or silicon into metallic material surfaces using liquids, e.g. salt baths, liquid suspensions
- C23C10/20—Solid state diffusion of only metal elements or silicon into metallic material surfaces using liquids, e.g. salt baths, liquid suspensions only one element being diffused
- C23C10/24—Salt bath containing the element to be diffused
-
- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
- C23C10/34—Embedding in a powder mixture, i.e. pack cementation
- C23C10/36—Embedding in a powder mixture, i.e. pack cementation only one element being diffused
- C23C10/48—Aluminising
-
- 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
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/04—Cleaning or pickling metallic material with solutions or molten salts with acid solutions using inhibitors
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/34—Pretreatment of metallic surfaces to be electroplated
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/48—After-treatment of electroplated surfaces
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrochemistry (AREA)
- Mechanical Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Abstract
The invention discloses a high-temperature oxidation resistance lifting method for a main valve rod of an in-service steam turbine, which comprises the steps of disassembling the valve rod of the steam turbine, cleaning the oxide skin on the surface of the valve rod by adopting an organic acid cleaning liquid, taking out the valve rod after most of the oxide skin is dissolved, washing the valve rod by using alkaline water, and drying by using cold air; then, polishing the valve rod by adopting a mechanical method, and cleaning up oxide skin on the surface of the valve rod; measuring the outer diameter of the valve rod, and determining the outer diameter reduction amount of the valve rod; electroplating Ni on the valve rod by adopting a brush plating method, and performing size compensation on the valve rod; finally, aluminizing the Ni-plated area to form Ni-Al alloy coating in the high temperature oxidation part of the valve rod. The invention is easy to realize, can prepare the Ni-Al alloy coating with strong high-temperature oxidation resistance and good wear resistance on the valve rod of the main steam valve of the in-service steam turbine, can compensate the fit clearance between the valve rod and the valve sleeve, and ensures the size fit requirement of the valve rod and the valve sleeve.
Description
Technical Field
The invention belongs to the technical field of high-temperature oxidation of materials, and particularly relates to a method for improving high-temperature oxidation resistance of a main valve rod of an in-service steam turbine.
Background
The high-medium pressure main valve and the valve regulating valve are protection devices for a thermal power or nuclear power unit steam turbine to rapidly cut off steam inlet of the steam turbine and realize shutdown, and the rapid switching of the protection devices is a key measure for preventing safety accidents such as galloping, shafting fracture, steam turbine scrapping and the like of the steam turbine due to overspeed. The problem of opening Guan Kase of the high and medium pressure main valve and the valve is a potential safety hazard for important prevention of a thermal power plant at present, and the generation and the falling of oxide skin on the surface of a material are one of main reasons for causing the blocking of the high and medium pressure main valve and the valve.
At present, during overhaul of the unit, the surface oxide skin of the valve seat, the valve disc sealing surface, the valve rod, the valve sleeve and other parts is cleaned in a sand paper polishing or lathe processing mode, but the valve rod and the valve sleeve have fit clearance requirements, and if the valve rod and the valve sleeve are polished improperly, the valve rod is scrapped. For the main valve rod of the in-service steam turbine, on one hand, the problem of oxide leather blocking needs to be solved, on the other hand, the high-temperature oxidation resistance of the material is improved, and on the other hand, the size compensation needs to be performed on the material loss of the valve rod caused by high-temperature oxidation.
The preparation of the high-temperature oxidation resistant coating is an effective means for improving the high-temperature oxidation resistant capability of the valve rod, and NiCr-Cr prepared by a supersonic flame spraying process at present 3 C 2 The coating has been applied in the thermal power field, and the process is mostly used for treating new valve rods made of high-grade alloy materials of ultra-supercritical units. The preparation process of the coating has more severe requirements, is not matched with a low-grade alloy valve rod used for a main valve of a supercritical unit and a subcritical unit, and is not suitable for repairing in-service valve rods. The aluminizing is another method for improving the high-temperature oxidation resistance of the material, the process requirement for preparing the coating is lower, but the size compensation effect of the coating is effective, and the coating is not suitable for repairing the valve rod of the in-service steam turbine.
Disclosure of Invention
The invention aims to solve the technical problems of the prior art, and provides a method for improving the high-temperature oxidation resistance of a main valve rod of an in-service steam turbine, which improves the high-temperature oxidation resistance of the main valve rod of the in-service steam turbine and compensates the size of the material loss of the valve rod caused by high-temperature oxidation.
The invention adopts the following technical scheme:
a method for improving the high-temperature oxidation resistance of the valve rod of a main valve of an in-service steam turbine comprises the steps of cleaning the surface of the valve rod of the steam turbine by adopting an organic acid cleaning solution, and then flushing the valve rod by using alkaline water; polishing the surface of the cleaned turbine valve rod; electroplating Ni on the valve rod of the steam turbine according to the reduction of the outer diameter of the valve rod of the steam turbine; and (3) aluminizing the Ni electroplated area of the valve rod of the steam turbine to form the Ni-Al alloy coating.
Specifically, the organic acid cleaning solution comprises, by mass, 4% -8% of a chemical cleaning agent, 0.3% -0.5% of a corrosion inhibitor and 0.1% -0.3% of a reducing agent.
Further, the chemical cleaning agent is one of citric acid, EDTA or glycolic acid.
Specifically, the temperature for cleaning the surface of the valve rod of the steam turbine by adopting the organic acid cleaning solution is 85-95 ℃.
Specifically, the concentration of alkaline water was 1%.
Further, the alkaline water is NaOH and Na 2 CO 3 Or ammonia.
Specifically, the surface of the valve rod of the steam turbine is polished by a mechanical method.
Specifically, ni is electroplated on the matching part of the valve rod and the valve sleeve of the steam turbine.
Further, the thickness of the electroplated Ni layer is 1/4 of the reduction of the outer diameter of the valve rod of the steam turbine.
Specifically, the aluminizing mode is slurry aluminizing or powder embedding aluminizing, and the aluminizing temperature is the lower limit of the tempering temperature of the valve rod material of the steam turbine.
Compared with the prior art, the invention has at least the following beneficial effects:
the method for improving the high-temperature oxidation resistance of the main valve rod of the in-service steam turbine is simple to operate and easy to realize. The valve rod can carry out size compensation on the material loss of the valve rod caused by high-temperature oxidation while improving the high-temperature oxidation resistance of the valve rod.
Further, the organic acid cleaning liquid comprises, by mass, 4% -8% of chemical cleaning agents, 0.3% -0.5% of corrosion inhibitors and 0.1% -0.3% of reducing agents, so that the cleaning effect of the organic acid cleaning liquid on oxide skin on the surface of a valve rod can be effectively ensured, and corrosion of a substrate can be controlled.
Furthermore, the temperature for cleaning the surface of the valve rod of the steam turbine by adopting the organic acid cleaning liquid is 85-95 ℃, so that the cleaning capability of the organic acid can be effectively ensured.
Furthermore, after the valve rod is chemically cleaned, the concentration of alkaline water used for flushing is 1%, so that the residual organic acid on the surface of the valve rod can be effectively neutralized.
Further, polishing the surface of the turbine valve rod after chemical cleaning to completely remove the oxide remained on the surface of the valve rod, thereby ensuring the binding force between the electroplated Ni layer and the substrate.
Further, the thickness of the electroplated Ni layer is 1/4 of the reduction of the outer diameter of the valve rod of the steam turbine, so that the outer diameter of the valve rod after aluminizing treatment is ensured to be restored to the original outer diameter.
Furthermore, the valve rod is subjected to aluminizing treatment after Ni is electroplated, so that a high-hardness and high-oxidation-resistance NiAl coating can be formed on the surface of the valve rod, and the valve rod has excellent wear resistance and high-temperature oxidation resistance.
In conclusion, the invention has simple operation and easy realization, and on the basis of improving the high-temperature oxidation resistance of the valve rod, the size compensation is carried out on the material loss of the valve rod caused by high-temperature oxidation.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is a schematic flow chart of the present invention.
Detailed Description
The following description of the present invention will be made clearly and fully, and it is apparent that the embodiments described are some, but not all, of the embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the present invention, all embodiments and preferred methods of implementation mentioned herein may be combined with each other to form new solutions, unless otherwise specified.
In the present invention, all technical features mentioned herein and preferred features may be combined with each other to form new technical solutions, unless otherwise specified.
In the present invention, the percentage (%) or parts refer to weight percentage or parts by weight relative to the composition unless otherwise specified.
In the present invention, the components or preferred components thereof may be combined with each other to form a new technical solution, unless otherwise specified.
In the present invention, unless otherwise indicated, the numerical ranges "a-b" represent shorthand representations of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6-22" means that all real numbers between "6-22" have been listed throughout, and "6-22" is only a shorthand representation of a combination of these values.
The "range" disclosed herein may take the form of a lower limit and an upper limit, which may be one or more lower limits and one or more upper limits, respectively.
In the present invention, the term "and/or" as used herein refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
In the present invention, each reaction or operation step may be performed sequentially or sequentially unless otherwise indicated. Preferably, the reaction processes herein are performed sequentially.
Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, any method or material similar or equivalent to those described may be used in the present invention.
The invention provides a high-temperature oxidation resistance lifting method for a main valve rod of an in-service steam turbine, which comprises the steps of disassembling the valve rod of the steam turbine, cleaning the oxide skin on the surface of the valve rod by adopting an organic acid cleaning liquid, taking out the valve rod after most of the oxide skin is dissolved, washing the valve rod by using alkaline water, and drying by using cold air; then, polishing the valve rod by adopting a mechanical method, and cleaning up oxide skin on the surface of the valve rod; measuring the outer diameter of the valve rod, and determining the outer diameter reduction amount of the valve rod; electroplating Ni on the valve rod by adopting a brush plating method, and performing size compensation on the valve rod; finally, aluminizing the Ni-plated area to form Ni-Al alloy coating in the high temperature oxidation part of the valve rod. The invention is easy to realize, can prepare the Ni-Al alloy coating with strong high-temperature oxidation resistance and good wear resistance on the valve rod of the main steam valve of the in-service steam turbine, can compensate the fit clearance between the valve rod and the valve sleeve, and ensures the size fit requirement of the valve rod and the valve sleeve.
Referring to fig. 1, the method for improving the high-temperature oxidation resistance of the valve rod of the main valve of the in-service steam turbine comprises the following steps:
s1, chemically cleaning oxide skin on the surface of a valve rod;
after the steam turbine valve rod with the problem of oxide scale blocking is disassembled, the steam turbine valve rod is placed into a cleaning tank, an organic acid cleaning solution is used for cleaning oxide scale on the surface of the valve rod, after most of the oxide scale is dissolved, the valve rod is taken out and is washed by low-concentration alkaline water, tap water is used for washing, and cold air is dried.
The cleaning agent comprises, by mass, 4% -8% of a chemical cleaning agent, 0.3% -0.5% of a corrosion inhibitor and 0.1% -0.3% of a reducing agent.
The chemical cleaning agent used for cleaning the valve rod is one of citric acid, EDTA or glycolic acid, and the cleaning agent also contains corrosion inhibitor and reducing agent (Fe is avoided in the cleaning process) 3+ The production of (2) the temperature of the cleaning agent is controlled between 85 and 95 ℃.
After the oxide skin on the surface of the valve rod is chemically cleaned, the flushing water adopted is alkaline solution with the concentration of 1 percent, and the alkaline solution is NaOH and Na 2 CO 3 Or ammonia.
S2, mechanically polishing;
and (3) polishing the valve rod by adopting a mechanical method (sand blasting or sand paper polishing), and cleaning up the residual oxide skin on the surface of the valve rod.
S3, size weighing;
and measuring the outer diameter of the valve rod by adopting a vernier caliper, and determining the outer diameter reduction amount of the valve rod.
S4, electroplating;
and electroplating Ni on the matching part of the valve rod and the valve sleeve by adopting an electroplating method, wherein the thickness of the electroplated Ni layer is controlled to be 1/4 of the reduction of the outer diameter of the valve rod.
The electroplating of the valve rod is performed in a brush plating or local electroplating mode, for example, local electroplating is adopted, and the area which is not subjected to electroplating needs to be protected by sealant before the valve rod is immersed into the electroplating liquid.
S5, aluminizing.
Aluminizing the electroplated Ni area of the matching part of the valve rod and the valve sleeve to form a Ni-Al alloy coating at the part of the valve rod, which is easy to oxidize at high temperature.
The local aluminizing of the valve rod Ni electroplating area is carried out in a slurry aluminizing or powder embedding aluminizing mode, the aluminizing temperature needs to be controlled at the lower limit of the tempering temperature of the valve rod material, if embedding aluminizing is adopted, a specific fixture needs to be processed to wrap the part to be subjected to local aluminizing, and the part not subjected to aluminizing needs to be coated with high-temperature resistant sealant for protection.
The invention relates to a method for improving the high-temperature oxidation resistance of a main valve rod of an in-service steam turbine, which is also suitable for the high-temperature oxidation resistance treatment of steam circulation components such as a regulating valve, a valve sleeve, a valve disc and the like of the steam turbine.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Examples
Firstly, dismantling a valve rod of a steam turbine with the problem of oxide scale blocking of a subcritical thermal power generating unit, putting the valve rod into a washing tank with a heating function, adopting a citric acid detergent (4% -8% of citric acid +0.3% -0.5% of corrosion inhibitor +0.1% -0.3% of reducing agent), washing oxide scale on the surface of the valve rod at 90 ℃, taking out the valve rod after most of the oxide scale is dissolved, performing alkaline neutralization washing by using 1% NaOH, washing by using tap water, and drying by cold air;
polishing the valve rod by adopting 800# abrasive paper, and cleaning up residual oxide skin on the surface of the valve rod; measuring the outer diameter of the valve rod by adopting a vernier caliper, referring to the standard size of the part, and determining the reduction amount of the outer diameter of the valve rod;
electroplating Ni on the matching part of the valve rod and the valve sleeve by adopting a solution and brush plating process, wherein the change of the outer diameter and the size of the valve rod is monitored in the electroplating process, when the thickness of an electroplated Ni layer reaches about 1/4 of the reduction of the outer diameter of the valve rod, the electroplating is stopped, and after the electroplating, the valve rod is required to be washed by water and dried by cold air;
finally, the Ni-electroplated part is subjected to powder embedding aluminizing, the part to be subjected to local aluminizing is firstly wrapped by adopting a fixture wrap, and the wrap is filled with an aluminizing agent (Al 2 O 3 ：Al：NH 4 Cl=70:20:10), coating high-temperature resistant sealant on the part which is not subjected to aluminizing for protection, after the sealant is dried, putting the valve rod into a vacuum furnace (650 ℃) for aluminizing, 8 hours later, cooling the valve rod along with the furnace to room temperature, taking out, removing a clamp sheath, removing the aluminizing agent and the high-temperature sealant on the surface of the valve rod, and polishing the surface of the valve rod by using 1000# abrasive paper.
In summary, the method for improving the high-temperature oxidation resistance of the valve rod of the main valve of the in-service steam turbine is simple to operate and easy to realize, and size compensation is performed on the material loss of the valve rod caused by high-temperature oxidation on the basis of improving the high-temperature oxidation resistance of the valve rod. .
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. A method for improving the high-temperature oxidation resistance of a main valve rod of an in-service steam turbine is characterized in that an organic acid cleaning solution is adopted to clean the surface of the valve rod of the steam turbine, and then alkaline water is used for washing; polishing the surface of the cleaned turbine valve rod; electroplating Ni on the valve rod of the steam turbine according to the reduction of the outer diameter of the valve rod of the steam turbine; and (3) aluminizing the Ni electroplated area of the valve rod of the steam turbine to form the Ni-Al alloy coating.
2. The method for improving the high-temperature oxidation resistance of the main valve rod of the in-service steam turbine according to claim 1, wherein the organic acid cleaning solution comprises, by mass, 4% -8% of a chemical cleaning agent, 0.3% -0.5% of a corrosion inhibitor and 0.1% -0.3% of a reducing agent.
3. The in-service steam turbine main valve stem high temperature oxidation resistance improvement method according to claim 2, wherein the chemical cleaning agent is one of citric acid, EDTA or glycolic acid.
4. The method for improving the high-temperature oxidation resistance of a main valve rod of an in-service steam turbine according to claim 1, wherein the temperature for cleaning the surface of the valve rod of the steam turbine by adopting an organic acid cleaning solution is 85-95 ℃.
5. The in-service steam turbine main valve stem high temperature oxidation resistance promotion method according to claim 1, wherein the concentration of alkaline water is 1%.
6. The method for improving the high-temperature oxidation resistance of the main valve rod of the in-service steam turbine according to claim 5, wherein the alkaline water is NaOH or Na 2 CO 3 Or ammonia.
7. The in-service steam turbine main valve stem high temperature oxidation resistant lifting method according to claim 1, wherein the surface of the steam turbine valve stem is polished mechanically.
8. The method for improving the high-temperature oxidation resistance of a main valve rod of an in-service steam turbine according to claim 1, wherein the matched part of the valve rod and the valve sleeve of the steam turbine is electroplated with Ni.
9. The in-service turbine main valve stem high temperature oxidation resistance promotion method according to claim 8, wherein the thickness of the electroplated Ni layer is 1/4 of the reduction of the turbine valve stem outer diameter.
10. The method for improving the high-temperature oxidation resistance of a main valve rod of an in-service steam turbine according to claim 1, wherein the aluminizing mode is slurry aluminizing or powder embedding aluminizing, and the aluminizing temperature is the lower limit of the tempering temperature of the valve rod material of the steam turbine.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311061838.7A CN117071019A (en) | 2023-08-22 | 2023-08-22 | High-temperature oxidation resistant lifting method for main valve rod of in-service steam turbine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311061838.7A CN117071019A (en) | 2023-08-22 | 2023-08-22 | High-temperature oxidation resistant lifting method for main valve rod of in-service steam turbine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117071019A true CN117071019A (en) | 2023-11-17 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311061838.7A Pending CN117071019A (en) | 2023-08-22 | 2023-08-22 | High-temperature oxidation resistant lifting method for main valve rod of in-service steam turbine |
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| Country | Link |
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| CN (1) | CN117071019A (en) |
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2023
- 2023-08-22 CN CN202311061838.7A patent/CN117071019A/en active Pending
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