CN112268827B - Thermal fatigue cracking resistant method for stainless steel hot molten salt pipeline of photo-thermal power station - Google Patents
Thermal fatigue cracking resistant method for stainless steel hot molten salt pipeline of photo-thermal power station Download PDFInfo
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- CN112268827B CN112268827B CN202011097760.0A CN202011097760A CN112268827B CN 112268827 B CN112268827 B CN 112268827B CN 202011097760 A CN202011097760 A CN 202011097760A CN 112268827 B CN112268827 B CN 112268827B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/60—Investigating resistance of materials, e.g. refractory materials, to rapid heat changes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/16—Investigating or analyzing materials by the use of thermal means by investigating thermal coefficient of expansion
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N3/04—Chucks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/20—Metals
- G01N33/204—Structure thereof, e.g. crystal structure
- G01N33/2045—Defects
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0057—Generation of the force using stresses due to heating, e.g. conductive heating, radiative heating
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0073—Fatigue
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/026—Specifications of the specimen
- G01N2203/0262—Shape of the specimen
- G01N2203/0274—Tubular or ring-shaped specimens
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0682—Spatial dimension, e.g. length, area, angle
Abstract
The invention discloses a method for resisting thermal fatigue cracking of a stainless steel thin-wall hot-melt salt pipeline of a photo-thermal power station, which comprises the following specific processes: 1) Obtaining the thermal fatigue cracking property and reason of the stainless steel hot molten salt pipeline of the photothermal power station through laboratory failure analysis, temperature difference and stress calculation and comprehensive analysis of a cracking sample; 2) The support of the hot-melt salt pipeline is reformed and comprises two guide frames, two H-shaped structural steel beams and four guard plates, wherein the two guard plates with 10mm-20mm axial gaps are arranged on the same side, the edges between the gaps are not welded with the pipeline, and the rest edges are welded with the pipeline; a gap of 5mm-10mm is reserved between the guide frame arranged on the same side and the H-shaped structural steel beam, and welding is not carried out. The method can reduce the axial expansion difference of the stainless steel hot molten salt pipeline, eliminate the cracking failure of the weak part of the pipeline, avoid the molten salt leakage of the photo-thermal power station in the operation and improve the safety of the photo-thermal power station.
Description
Technical Field
The invention belongs to the technical field of safety protection of new energy thermal pipelines, and particularly relates to a thermal fatigue cracking resistance method for a stainless steel hot molten salt pipeline of a photo-thermal power station.
Background
With the development of solar photo-thermal power generation technology, in recent years, a fused salt tower type photo-thermal power station gradually becomes a new power generation mode, a hot fused salt pipeline is a thin-wall pipeline made of TP347H stainless steel, working media in the pipeline are hot fused salt, the pressure of the working media is 0.04bar-40.73bar, the power station is started and stopped at least 1 time every day according to weather conditions, namely the wall temperature of the hot fused salt pipeline changes more than one week every day, the working media temperature of the pipeline in each day is the highest at noon and the lowest at night, and the lifting rate of the wall temperature of the pipeline is higher.
Because the linear expansion coefficient of the stainless steel material is larger than that of ferrite steel, the hot-melt salt pipeline frequently generates thermal fatigue cracking failure at the root of a fillet weld due to the axial expansion difference between the limiting support and the pipeline in operation, and the limiting supports on the hot-melt salt pipelines are welded with the outer wall of the pipeline by using four edges of a curved surface square protection plate.
At present, the treatment of stainless steel hot molten salt pipelines is only to replace pipe sections with cracking leakage, and the method is not an effective solution, fails to provide an effective solution from the cracking property and the cracking reason of the pipelines, needs to consume a large amount of manpower and material resources, has huge potential safety hazards, and is not beneficial to the long-term safe operation of a photo-thermal power station.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method for preventing thermal fatigue cracking of a stainless steel hot molten salt pipeline of a photo-thermal power station, which is used for eliminating cracking failure of a weak part of the pipeline, avoiding molten salt leakage in the running of the photo-thermal power station and improving the safety of the photo-thermal power station.
The invention is realized by adopting the following technical scheme:
a method for preventing thermal fatigue cracking of a stainless steel hot molten salt pipeline of a photo-thermal power station comprises the following steps:
1) The method comprises the steps of obtaining the material state, the cracking position, the crack trend, the cracking mechanism and the position relation of a limiting bracket of a fillet weld between a pipeline parent metal and the bracket through laboratory failure analysis of a cracking sample and a test, calculating the quantitative relation between the axial expansion difference between the pipeline and a bracket guard plate and the temperature difference and thermal expansion stress, and comprehensively analyzing the thermal fatigue cracking property and reason of the stainless steel hot molten salt pipeline of the photothermal power station;
2) Reform transform the support of hot melt salt pipeline, include: the device comprises two guide frames, two H-shaped structural steel beams and four guard plates;
each side of the hot-melt salt pipeline comprises a guide frame, an H-shaped structural steel beam and two guard plates, and the guide frames, the H-shaped structural steel beams and the two guard plates are symmetrically arranged on two sides of the hot-melt salt pipeline; an axial gap is left between the two guard plates on the same side, and the other 6 edges are welded with the hot-melt salt pipeline; one end of the guide frame is welded with the two corresponding guard plates, the H-shaped structural steel beam is clamped in a groove at one end of the guide frame, and a radial gap is reserved between the end part of the guide frame and the H-shaped structural steel beam.
The invention is further improved in that the pipeline cracking position is the root of a transverse fillet weld between the pipeline and the support guard plate.
A further improvement of the invention is that the cracking property of the pipe is thermal fatigue cracking.
The invention has the further improvement that the axial expansion difference delta l between the pipeline and the bracket protecting plate is calculated according to a formula of delta l = delta T lambda, wherein, delta T is the wall temperature difference between the pipeline and the bracket protecting plate and is in DEG C; lambda-coefficient of linear expansion of the pipeline and the stent panel, 1/deg.C.
The invention is further improved in thatΔTThe thermal expansion stress sigma between the pipeline and the bracket guard plate is calculated by the formula = (delta l/l) EΔTIn the formula, delta T is the axial expansion difference between the pipeline and the support guard plate, and is DEG C; l is axial length of the guard plate, mm, E is elastic modulus, MPa.
The invention is further improved in that the two guide frames and the four guard plates are made of the same stainless steel material as the pipeline.
The invention is further improved in that the axial gap between two guard plates arranged on the same side is between 10mm and 20 mm.
A further development of the invention is that the edges of the axial gap between the two cover plates are not welded to the pipe.
The invention is further improved in that a radial gap between the guide frame arranged on the same side and the H-shaped structural steel beam is between 5 and 10 mm.
The invention is further improved in that the radial clearance left between the guide frame and the H-shaped structural steel beam is not welded.
The invention has at least the following beneficial technical effects:
according to the invention, through laboratory failure analysis, temperature difference and thermal expansion stress calculation and comprehensive analysis of a cracking sample, the cracking position, property and reason of the stainless steel hot molten salt pipeline of the photothermal power station, and the quantitative relation between the axial expansion difference between the guard plates and the temperature difference and thermal expansion stress are mastered, and reference data are provided for solving the thermal fatigue cracking of the stainless steel hot molten salt pipeline.
The limiting support is structurally transformed, the axial expansion difference between the two support guard plates on the same side is absorbed through a proper amount of axial gaps between the two support guard plates, the radial expansion difference of the pipeline is absorbed through a proper amount of radial gaps between the guide frame and the H-shaped structural steel beam, the axial expansion difference of the stainless steel hot molten salt pipeline is reduced, the cracking failure of the weak part of the pipeline is eliminated, molten salt leakage in the operation of the photo-thermal power station is avoided, and the safety of the photo-thermal power station is improved.
Drawings
FIG. 1 is a schematic diagram of a limiting bracket structure of a reconstructed stainless steel hot molten salt pipeline cracking part of a photo-thermal power station;
fig. 2 is a schematic flow chart of the technical solution provided by the present invention.
Description of reference numerals: 1 is a hot-melt salt pipeline, 2 is a guide frame, 3 is a guard plate, and 4 is an H-shaped structural steel beam.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
as shown in FIG. 2, the method for resisting thermal fatigue cracking of the stainless steel hot molten salt pipeline of the photothermal power station provided by the invention specifically comprises the following steps:
1) The method comprises the steps of obtaining material states, cracking positions, crack trends, cracking mechanisms and position relations between the material states, the cracking positions, the crack trends and the position relations between the material states, the cracking mechanisms and the limiting supports of the fillet welds between a pipeline parent metal and the supports through laboratory failure analysis of cracking samples, obtaining parameters of the hot-melt salt pipeline from a real-time production database, wherein the parameters comprise materials, specifications, pipeline diagrams, working medium pressure, working medium temperature change curves, working medium flow, loads and the like, obtaining quantitative relations between axial expansion differences, temperature differences and thermal expansion stresses between the pipeline and support protection plates according to material mechanics calculation, and obtaining thermal fatigue cracking properties and reasons of the stainless steel hot-melt salt pipeline of the photo-thermal power station through comprehensive analysis.
Calculating the axial expansion difference delta l between the pipeline and the support guard plate according to a delta l = delta T lambda formula, wherein delta T is the wall temperature difference between the pipeline and the support guard plate, and the temperature is DEG C; lambda-coefficient of linear expansion of the pipe and the stent sheathing, 1/deg.C.
According to σΔTThe thermal expansion stress sigma between the pipeline and the bracket guard plate is calculated by a = (delta l/l) E formulaΔTIn the formula, delta T is the axial expansion difference between the pipeline and the bracket guard plate at DEG C; l is the axial length of the guard plate, mm, E is the elastic modulus, MPa.
2) Reform transform the support of hot melt salt pipeline, include: the device comprises two guide frames 2, two H-shaped structural steel beams 4 and four guard plates 3;
wherein, an axial gap is left between the two guard plates 3 on the same side, and the other 6 edges are welded with the hot-melt salt pipeline 1; 2 one ends of guide frame and two corresponding backplate 3 welding, H shaped structure girder steel 4 card are in 2 one end recesses of guide frame, leave radial clearance between the tip of guide frame 2 and the H shaped structure girder steel 4.
As shown in FIG. 1, the axial clearance between two guard plates 3 arranged on the same side is between 10mm and 20 mm; at the same time, the edges of the axial gap between the two shields 3 are not welded to the pipe.
The axial gap between the two guard plates can absorb the axial expansion difference caused by the temperature difference between the pipeline and the guard plates, so that the alternating thermal stress of the fillet weld part between the pipeline and the guard plates is greatly reduced;
as shown in fig. 1, a radial gap between the guide frame arranged on the same side and the H-shaped structural steel beam 4 is 5mm to 10mm, and meanwhile, the radial gap between the guide frame and the H-shaped structural steel beam 4 is not welded.
The radial clearance between the guide frame and the H-shaped structural steel beam 4 can absorb the radial expansion of the pipeline, and the pipeline is prevented from having no radial expansion space.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention, and such modifications and adaptations are intended to be within the scope of the invention.
Claims (5)
1. A method for preventing thermal fatigue cracking of a stainless steel hot molten salt pipeline of a photo-thermal power station is characterized by comprising the following steps:
1) The method comprises the following steps of (1) obtaining the material state, the cracking position, the crack trend, the cracking mechanism of a pipe parent metal and a fillet weld between the pipe parent metal and a bracket and the position relation of a limiting bracket through laboratory failure analysis of a cracking sample, calculating the quantitative relation between the axial expansion difference between the pipe and a bracket guard plate, the temperature difference and the thermal expansion stress, and comprehensively analyzing the thermal fatigue cracking property and reason of the stainless steel hot molten salt pipe of the photothermal power station;
2) Reform transform the support of hot melt salt pipeline, include: the steel plate comprises two guide frames (2), two H-shaped structural steel beams (4) and four guard plates (3);
each side of the hot-melt salt pipeline (1) comprises a guide frame (2), an H-shaped structural steel beam (4) and two guard plates (3) which are symmetrically arranged on two sides of the hot-melt salt pipeline (1); an axial gap is reserved between the two guard plates (3) on the same side, the other 6 edges are welded with the hot-melt salt pipeline (1), wherein the axial gap between the two guard plates (3) arranged on the same side is between 10mm and 20mm, and the edge of the axial gap between the two guard plates (3) is not welded with the pipeline; one end of the guide frame (2) is welded with the two corresponding guard plates (3), the H-shaped structural steel beam (4) is clamped in a groove at one end of the guide frame (2), a radial gap is reserved between the end part of the guide frame (2) and the H-shaped structural steel beam (4), the radial gap reserved between the guide frame and the H-shaped structural steel beam (4) which are arranged on the same side is between 5mm and 10mm, and the radial gap reserved between the guide frame and the H-shaped structural steel beam (4) is not welded.
2. The method for resisting thermal fatigue cracking of a stainless steel hot molten salt pipeline of a photothermal power station according to claim 1, wherein the cracking position of the pipeline is the root of a transverse fillet weld between the pipeline and a support guard plate.
3. The method for resisting thermal fatigue cracking of a stainless steel hot molten salt pipeline of an photothermal power station according to claim 1, wherein an axial expansion difference Δ l between the pipeline and the support guard plate is calculated according to a formula of Δ l = Δ T · λ, where Δ T is a wall temperature difference, ° c, between the pipeline and the support guard plate; lambda-coefficient of linear expansion of the pipe and the stent sheathing, 1/deg.C.
4. The method of claim 3 for resisting thermal fatigue cracking of stainless steel hot molten salt pipelines of photothermal power stations, wherein the method is based on sigmaΔTCalculating the thermal expansion stress sigma between the pipeline and the bracket guard plate by using a = (delta l/l) E formulaΔTIn the formula, delta l is the axial expansion difference between the pipeline and the support guard plate, DEG C; l is axial length of the guard plate, mm, E is elastic modulus, MPa.
5. The method for resisting thermal fatigue cracking of a stainless steel hot molten salt pipeline for a photothermal power station according to claim 1, wherein the two guide frames (2) and the four protecting plates (3) are made of the same stainless steel material as the pipeline.
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