Method, system and equipment for predicting flow accelerated corrosion distribution of bent pipe

Abstract

The invention relates to a method, a system and equipment for predicting flow accelerated corrosion distribution of a bent pipe. The method comprises the following steps: acquiring elbow pipe information and environment information for a to-be-predicted elbow pipe; establishing a geometric model of the bent pipe to be predicted according to the bent pipe information; according to the environment information, physical fields of the geometric model of the to-be-predicted elbow are simulated, the geometric model provided with physical fields is obtained, and the physical fields comprise a secondary current distribution physical field, a dilute material transfer physical field and a flow field physical field; and calculating the corrosion rate distribution of the bent pipe to be predicted according to the geometric model provided with the physical field. According to the method, the integration of chemical reaction, interface electrochemical reaction and mass transfer process of species is fully considered, the corrosion rate distribution of the bent pipe can be predicted more accurately, and theoretical basis and guidance are provided for accelerated corrosion and protection of pipeline flow.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion prediction, and in particular to a method, system and equipment for predicting the distribution of accelerated corrosion in curved pipe flow. Background Art

[0002] Flow-accelerated corrosion is corrosion caused by turbulent disturbance of fluids that do not contain solid particles or contain solid particles of lower concentration and smaller size. The flow of fluid in the pipeline accelerates the mass transfer process of near-wall species and destroys the protective corrosion product film formed on the inner surface of the pipeline, resulting in extremely destructive flow-accelerated corrosion in a carbon dioxide environment, which often causes premature failure of oil and gas pipelines. Especially in the weak links of pipelines such as elbows, the direction of fluid movement changes dramatically, resulting in more serious flow-accelerated corrosion at the elbows, and the flow-accelerated corrosion rates at different positions of the elbows are significantly different. Therefore, accurately predicting the distribution of flow-accelerated corrosion rates at different positions of the elbow is particularly important for flow-accelerated corrosion protection in oil and gas fields, and can provide necessary guarantees for the safe transportation of oil and gas pipelines.

[0003] At present, there are three methods for establishing a carbon dioxide corrosion prediction model, namely, an empirical model establishment method, a semi-empirical model establishment method, and a mechanism model establishment method. Among them, the empirical model relies on experiments and original data from oil and gas fields, and the corrosion prediction deviation for other working conditions outside the model establishment conditions is large. The semi-empirical model is difficult to be popularized in other environments because the interaction between the influencing factors involved in the corrosion process is very complex. Since each parameter used in the mechanism model has a clear physical meaning, the mechanism model can be modified and optimized to apply to a wider range of working conditions. In addition, only a small amount of experimental data is used to verify the accuracy and effectiveness of the model, so the use of the mechanism model greatly reduces the experimental cost. In contrast, corrosion prediction in harsh and complex oil and gas production environments prefers the mechanism model establishment method.

[0004] In addition, the current prediction methods for elbow corrosion under flow conditions, on the one hand, the established empirical or semi-empirical models strongly rely on a large amount of experimental data, and therefore have a narrow scope of application. Furthermore, the mass transfer of species near the wall can be determined by computational fluid dynamics methods to predict the erosion and wear distribution of three-dimensional elbows, but this method completely ignores the thermodynamics and kinetics involved in chemical and electrochemical reactions. Flow-accelerated corrosion prediction of three-dimensional geometric models of elbows is more in line with the actual working conditions of oil and gas pipeline transportation, but because the flow-accelerated corrosion prediction of three-dimensional elbow models is much more difficult than that of two-dimensional models, so far, there has been no real model for the prediction mechanism of three-dimensional elbow corrosion under flow conditions. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method, system and device for predicting the distribution of accelerated corrosion in curved pipe flow, so as to solve the above technical problem.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a method for predicting the distribution of accelerated corrosion in a curved pipe flow, comprising: obtaining curved pipe information and environmental information for the curved pipe to be predicted, wherein the curved pipe information is information describing the material and structure of the curved pipe to be predicted, and the environmental information is information describing the fluid environment in the curved pipe to be predicted; establishing a geometric model of the curved pipe to be predicted based on the curved pipe information; simulating the physical field of the geometric model of the curved pipe to be predicted based on the environmental information to obtain a geometric model with a physical field, wherein the physical field includes a secondary current distribution physical field, a dilute species transfer physical field and a flow field physical field, wherein the secondary current distribution physical field is used to characterize the distribution of current on the electrode surface, the dilute species transfer physical field is used to characterize the migration, diffusion and convection phenomena of the material in the curved pipe to be predicted, and the flow field physical field is used to characterize the flow of the fluid in the curved pipe to be predicted; and calculating the corrosion rate distribution of the curved pipe to be predicted based on the geometric model with a physical field.

[0007] The beneficial effects of the present invention are as follows: the present invention realizes simulation calculation of corrosion rate distribution of the bend to be predicted by establishing a geometric model of the bend to be predicted, and setting secondary current distribution physical field, dilute material transfer physical field and flow field physical field for the geometric model. The present invention fully considers the integration of chemical reaction, interfacial electrochemical reaction and species mass transfer process, and can more accurately predict the corrosion rate distribution of the bend, providing theoretical basis and guidance for pipeline flow accelerated corrosion and protection.

[0008] Based on the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, the corrosion rate distribution of the elbow to be predicted is calculated based on the geometric model provided with a physical field, including: obtaining the initial conditions of the geometric model provided with a physical field, the initial conditions are used to describe the initial state of the geometric model provided with a physical field; based on the initial conditions, performing multi-physical field coupling processing on each of the physical fields to calculate the current density distribution; and calculating the corrosion rate distribution of the elbow to be predicted based on the current density distribution.

[0010] Further, the initial conditions include the initial concentrations of each first substance, each of the first substances represents a substance participating in the chemical reaction involved in the flow-accelerated corrosion process in the elbow to be predicted, and the initial concentrations of each first substance are obtained in the following manner: determining the chemical reaction involved in the flow-accelerated corrosion process in the elbow to be predicted; calculating the equilibrium constants corresponding to each chemical reaction based on the environmental information; calculating the initial concentrations of each first substance based on the equilibrium constants corresponding to each chemical reaction and the equilibrium constant calculation formula corresponding to each chemical reaction.

[0011] Further, based on the initial conditions, performing multi-physical field coupling processing on each of the physical fields to calculate the current density distribution includes: based on the initial conditions, performing multi-physical field coupling processing on each of the physical fields, and calculating the current density distribution in combination with the first formula and the second formula;

[0012] The first formula is:

[0013]

[0014] Among them, u i is the electrical mobility of substance i, D i is the molecular diffusion coefficient of substance i, R is the universal gas constant, and T is the fluid temperature;

[0015] The second formula is:

[0016] i a / c =F∑ i z i N i ;

[0017] Among them, i a / c is the anode or cathode current density on the electrode surface, F is the Faraday constant, z i is the charge number of substance i, N i is the total flux of substance i.

[0018] Further, the corrosion rate distribution of the elbow to be predicted is calculated according to the current density distribution, including: according to the current density distribution, the corrosion rate of each position of the elbow to be predicted is calculated by a third formula, and the third formula is:

[0019]

[0020] Among them, V corr is the corrosion rate, M Fe is the molar mass of iron, n is the number of electrons transferred in the iron dissolution half-cell reaction, F is the Faraday constant, and p is Fe is the density of iron, i is the local current density;

[0021] According to the corrosion rates of various positions of the bend pipe to be predicted, the corrosion rate distribution of the bend pipe to be predicted is obtained.

[0022] Furthermore, the flow field physics is simulated in the following manner: calculating the Reynolds number in the bend to be predicted according to the environmental information; simulating the flow field physics using a turbulence model or a laminar model according to the Reynolds number in the bend to be predicted.

[0023] Furthermore, the description equation of the physical field of the dilute species transfer is the Nernst-Planck transport equation.

[0024] In order to solve the above technical problems, the present invention also proposes a prediction system for accelerated corrosion distribution in elbow flow, comprising:

[0025] An information acquisition module, used to acquire the bend information and environmental information of the bend to be predicted, wherein the bend information is information describing the material and structure of the bend to be predicted, and the environmental information is information describing the fluid environment in the bend to be predicted;

[0026] A model building module, used to build a geometric model of the bend to be predicted according to the bend information;

[0027] A physical field setting module, used to simulate the physical field of the geometric model of the bend to be predicted according to the environmental information, and obtain a geometric model provided with a physical field, wherein the physical field includes a secondary current distribution physical field, a dilute material transfer physical field and a flow field physical field, wherein the secondary current distribution physical field is used to characterize the distribution of the current on the electrode surface, the dilute material transfer physical field is used to characterize the migration, diffusion and convection phenomena of the material in the bend to be predicted, and the flow field physical field is used to characterize the flow of the fluid in the bend to be predicted;

[0028] The corrosion rate distribution calculation module is used to calculate the corrosion rate distribution of the elbow to be predicted according to the geometric model provided with the physical field.

[0029] In order to solve the above technical problems, the present invention also proposes an electronic device, including a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a method for predicting the distribution of accelerated corrosion in curved pipe flow as described above is implemented.

[0030] To solve the above technical problems, the present invention also proposes a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions are used to enable a computer to execute a method for predicting the distribution of accelerated corrosion in a curved pipe flow as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of a method for predicting the distribution of accelerated corrosion in elbow flow according to the present invention;

[0032] Figure 2 A schematic diagram of a geometric model of a method for predicting accelerated corrosion distribution in a curved pipe flow according to the present invention;

[0033] Figure 3 A corrosion rate distribution cloud diagram of a method for predicting accelerated corrosion distribution in a curved pipe flow according to the present invention;

[0034] Figure 4 A graph showing the change in corrosion rate of the outermost side of a bend along the flow direction of a method for predicting flow-accelerated corrosion distribution of a bend according to the present invention;

[0035] Figure 5 A graph showing the variation of the corrosion rate of the innermost side of a bend along the flow direction of a method for predicting the distribution of flow-accelerated corrosion in a bend according to the present invention;

[0036] Figure 6 A diagram showing changes in anode current density and cathode current density along the outermost side of a bend pipe according to a method for predicting flow accelerated corrosion distribution in a bend pipe of the present invention;

[0037] Figure 7 A diagram showing changes in anode current density and cathode current density along the innermost side of a bend pipe according to a method for predicting flow accelerated corrosion distribution in a bend pipe of the present invention;

[0038] Figure 8 This is a schematic diagram of a prediction system for accelerated corrosion distribution in curved pipe flow according to the present invention. DETAILED DESCRIPTION

[0039] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0040] like Figure 1As shown, this embodiment provides a method for predicting the distribution of flow-accelerated corrosion in a bend, comprising: S1, obtaining bend information and environmental information for the bend to be predicted, wherein the bend information is information describing the material and structure of the bend to be predicted, and the environmental information is information describing the fluid environment in the bend to be predicted; S2, establishing a geometric model of the bend to be predicted based on the bend information; S3, simulating the physical field of the geometric model of the bend to be predicted based on the environmental information to obtain a geometric model with a physical field, wherein the physical field includes a secondary current distribution physical field, a dilute species transfer physical field and a flow field physical field, wherein the secondary current distribution physical field is used to characterize the distribution of current on the electrode surface, the dilute species transfer physical field is used to characterize the migration, diffusion and convection phenomena of the material in the bend to be predicted, and the flow field physical field is used to characterize the flow of the fluid in the bend to be predicted; S4, calculating the corrosion rate distribution of the bend to be predicted based on the geometric model with a physical field.

[0041] The bend information is information describing the material and structure of the bend to be predicted. For example, the bend with prediction is a 90° bend, which consists of three parts: the straight pipe section before the bend, the bend section, and the straight pipe section after the bend. The inner diameter of the bend to be predicted is 50 mm, the curvature radius of the bend is 77 mm, the length of the straight pipe section before the bend is 1 m, the length of the straight pipe section after the bend is 0.5 m, and the material of the bend is carbon steel.

[0042] Environmental information is information describing the fluid environment in the elbow to be predicted. For example, the fluid in the elbow to be predicted is simulated formation water of an oil field saturated with CO2. The simulated formation water is mainly composed of Na + , K + , Ca 2+ Mg 2+ , Cl - 、SO4 2- and HCO3 - Composition, the fluid flow rate is 4m / s.

[0043] Through multi-physics simulation software, such as COMSOL Multiphysics simulation software, the geometric model of the pipe bend to be predicted is constructed, such as Figure 2 As shown, the physical field is set for the geometric model of the elbow to be predicted. According to the elbow parameters and environmental parameters, the parameters of the geometric model are set, including the elbow material properties; the conductivity, density, and dynamic viscosity of the electrolyte (simulated formation water saturated with carbon dioxide); the ambient temperature (temperature of the fluid in the elbow) and the pressure (pressure in the elbow), etc.

[0044] Optionally, in an embodiment, calculating the corrosion rate distribution of the elbow to be predicted based on the geometric model provided with a physical field includes: obtaining the initial conditions of the geometric model provided with a physical field, wherein the initial conditions are used to describe the initial state of the geometric model provided with a physical field; based on the initial conditions, performing multi-physical field coupling processing on each of the physical fields to calculate the current density distribution; and calculating the corrosion rate distribution of the elbow to be predicted based on the current density distribution.

[0045] Set the initial conditions and boundary conditions of the model, specifically: the end face of the straight pipe section before the bend is set as the turbulent inlet, the end face of the straight pipe section after the bend is set as the turbulent outlet, select the fluid flow as fully developed flow, consider gravity, and set the inlet velocity and initial concentration of each substance.

[0046] Multi-physics field coupling processing is performed on each of the physical fields, and the model is meshed using a free tetrahedral mesh. A parametric sweep is set to couple the variables in the dilute species transport, secondary current distribution, and flow field with a relative tolerance of 0.0001 for the steady-state solver. The corrosion rate distribution at different positions of the elbow is obtained by combining the first formula, the second formula, and the Nernst-Planck transport equation, such as Figure 3 shown.

[0047] Optionally, in an embodiment, the initial conditions include the initial concentrations of each first substance, each of the first substances represents a substance participating in a chemical reaction involved in the flow-accelerated corrosion process in the elbow to be predicted, and the initial concentrations of each first substance are obtained in the following manner: determining the chemical reactions involved in the flow-accelerated corrosion process in the elbow to be predicted; calculating the equilibrium constants corresponding to each chemical reaction based on the environmental information; and calculating the initial concentrations of each first substance based on the equilibrium constants corresponding to each chemical reaction and the equilibrium constant calculation formulas corresponding to each chemical reaction.

[0048] In the process of flow accelerated corrosion, the following chemical reactions are involved:

[0049] 1.

[0050] The equilibrium constant calculation formula for this reaction is:

[0051]

[0052] The empirical formula for calculating the equilibrium constant corresponding to this reaction is:

[0053] 2. The equilibrium constant calculation formula for this reaction is:

[0054] The empirical formula for calculating the equilibrium constant corresponding to this reaction is:

[0055] 3. The equilibrium constant calculation formula for this reaction is:

[0056] The empirical formula for calculating the equilibrium constant corresponding to this reaction is:

[0057]

[0058] 4. The equilibrium constant calculation formula for this reaction is:

[0059] The empirical formula for calculating the equilibrium constant corresponding to this reaction is:

[0060]

[0061] 5. The equilibrium constant calculation formula for this reaction is:

[0062] The empirical formula for calculating the equilibrium constant corresponding to this reaction is:

[0063]

[0064] In each empirical formula, T and Tf are both ambient temperatures, T f is the temperature in Fahrenheit and T is the temperature in Kelvin. s is the saturated vapor pressure of water (bar). In this embodiment, P s =1bar. I is the ionic strength, calculated as follows:

[0065]

[0066] Among them, m i represents the molar concentration of ions in formation water, z i Represents ionic charge.

[0067] In each equilibrium constant calculation formula, K sol , K hyd , K ca , K bi and K wa is the equilibrium constant of each reaction, a i is the activity of substance i, is the CO2 fugacity, c i is the concentration of substance i, is the partial pressure of CO2, Y +is the average ion activity coefficient in the electrolyte. φ is the fugacity coefficient, which is determined according to the following formula:

[0068] logφ=P(0.0031-1.4 / T);

[0069] Where P is pressure and T is ambient temperature.

[0070] Combined with the above formula, calculate the equilibrium concentration of each substance in the above chemical reaction as the initial concentration of the substance. Taking the ambient temperature as 60°C and the pressure as 1MPa as an example, the initial concentration of each first substance is: 1.35×10 -2 mol / L; 2.32×10 -5 mol / L; 5.84×10 -3 mol / L; 2.34×10 -7 mol / L; 2.71×10 -6 mol / L; is 6.43×10 -8 mol / L; pH value is 5.57.

[0071] Optionally, in an embodiment, performing multi-physical field coupling processing on each of the physical fields based on the initial conditions to calculate the current density distribution includes:

[0072] Based on the initial conditions, multi-physics field coupling processing is performed on each of the physical fields, and the current density distribution is calculated by combining the first formula and the second formula;

[0073] The first formula is:

[0074]

[0075] Among them, u i is the electrical mobility of substance i, D i is the molecular diffusion coefficient of substance i, R is the universal gas constant, and T is the fluid temperature;

[0076] The second formula is:

[0077] i a / c =F∑ i z i N i ;

[0078] Among them, i a / c is the anode or cathode current density on the electrode surface, F is the Faraday constant, z i is the charge number of substance i, Ni is the total flux of substance i.

[0079] The electrochemical reactions involved in the flow accelerated corrosion process include the following:

[0080] Fe→Fe 2+ +2e - ;

[0081] 2H + +2e - →H2;

[0082] 2H2CO3+2e - →H2+2HCO3 - ;

[0083] 2HCO3 - +2e - →H2+2CO3 2- ;

[0084] 2H2O+2e - →H2+2OH - .

[0085] The reaction rate of each electrochemical reaction is kinetically expressed by the Tafe1 equation as the anode current density (i a ) or cathode current density (i c ), see the following formula:

[0086]

[0087] Where, E is the surface potential of carbon steel (V), E rev is the reversible potential (V), b is the Tafel slope (V), i 0，a and i 0,c (A / cm 2 ) are the exchange current densities of the anodic reaction and the cathodic reaction, respectively.

[0088] The exchange current density of species at the steel / solution interface can be determined according to the following formula:

[0089]

[0090] Where i0 is the exchange current density, i 0,ref is the reference exchange current density, E a is the activation energy, T ref is the reference temperature. The electrochemical reaction parameters used to calculate the exchange current density are shown in Table 1.

[0091] Table 1 Electrochemical reaction parameters

[0092]

[0093]

[0094] During the carbon dioxide corrosion process, the anodic reaction current density and the cathodic reaction current density on the carbon steel surface should follow the charge balance equation:

[0095]

[0096] in, is the cathode current density of the hydrogen reduction reaction, is the cathode current density of the carbonic acid reduction reaction, It is HCO3 - The cathode current density of the reduction reaction, is the cathode current density of the H2O reduction reaction.

[0097] Optionally, in an embodiment, calculating the corrosion rate distribution of the elbow to be predicted according to the current density distribution includes:

[0098] According to the current density distribution, the corrosion rate of each position of the elbow to be predicted is calculated by a third formula, and the third formula is:

[0099]

[0100] Among them, V corr is the corrosion rate, M Fe is the molar mass of iron (kg / mol), n is the number of electron transfers in the iron dissolution half-cell reaction (n=2), F is the Faraday constant, ρ Fe is the density of iron (kg / m 3 ), i is the local current density;

[0101] According to the corrosion rates of various positions of the bend pipe to be predicted, the corrosion rate distribution of the bend pipe to be predicted is obtained.

[0102] In this embodiment, the expression of the third formula is:

[0103]

[0104] The corrosion rate is thus calculated in years and the consistency of the units is ensured.

[0105] Optionally, in an embodiment, the flow field physical field is simulated in the following manner: calculating the Reynolds number in the bend to be predicted based on the environmental information; simulating the flow field physical field using a turbulence model or a laminar model based on the Reynolds number in the bend to be predicted.

[0106] The formula for calculating the Reynolds number is:

[0107] Re = ρvd / μ;

[0108] Where, v is the flow velocity (m / s), ρ is the density (kg / m 3 ), d is the hydraulic diameter (m), μ is the viscosity of the fluid (Pa.s).

[0109] Specifically, when the Reynolds number is less than 2000, it is determined that the flow field physics field is described by a laminar model; when the Reynolds number is greater than 4000, it is determined that the flow field physics field is described by a turbulent model. In this embodiment, the turbulence model is a k-ε turbulence model. The velocity field in the bend to be predicted is obtained by simulating and calculating the fluid dynamics parameters in a steady-state form through the flow field physics field.

[0110] Optionally, in an embodiment, the description equation of the physical field of the dilute species transfer is the Nernst-Planck transport equation.

[0111] Specifically, the Nernst-Planck transport equation is:

[0112]

[0113] Among them, N i is the total flux of substance i, D i is the molecular diffusion coefficient of substance i (m 2 / s), c i is the concentration of substance i (mol·m -3 ), z i is the charge number of substance i, u i is the electrical mobility of substance i (mol·s·kg -1 ), F is the Faraday constant (96485C / mol), φ is the electric potential of the fluid (V), and v is the instantaneous velocity of the fluid (m / s).

[0114] like Figure 4 and Figure 5 As shown in the figure, the prediction results show that the corrosion rate is larger on the inner side of the elbow and smaller on the outer side of the elbow. The corrosion rate first decreases and then increases along the outermost side of the elbow, while it first increases and then decreases along the innermost side of the elbow. Figure 6 and Figure 7 As shown, the predicted anode current density and cathode current density first decrease and then increase along the outermost side of the elbow, while they first increase and then decrease along the innermost side of the elbow.

[0115] In summary, the present invention establishes a geometric model of the elbow to be predicted, and sets the secondary current distribution physical field, the dilute material transfer physical field and the flow field physical field for the geometric model to achieve the simulation calculation of the corrosion rate distribution of the elbow to be predicted. The present invention fully considers the comprehensive chemical reaction, interfacial electrochemical reaction and the mass transfer process of species, and can more accurately predict the corrosion rate distribution of the elbow, providing a theoretical basis and guidance for pipeline flow accelerated corrosion and protection.

[0116] Embodiment 2

[0117] like Figure 8 As shown, this embodiment provides a prediction system for accelerated corrosion distribution in curved pipe flow, including:

[0118] An information acquisition module, used to acquire the bend information and environmental information of the bend to be predicted, wherein the bend information is information describing the material and structure of the bend to be predicted, and the environmental information is information describing the fluid environment in the bend to be predicted;

[0119] A model building module, used to build a geometric model of the bend to be predicted according to the bend information;

[0120] A physical field setting module, used to simulate the physical field of the geometric model of the bend to be predicted according to the environmental information, and obtain a geometric model provided with a physical field, wherein the physical field includes a secondary current distribution physical field, a dilute material transfer physical field and a flow field physical field, wherein the secondary current distribution physical field is used to characterize the distribution of the current on the electrode surface, the dilute material transfer physical field is used to characterize the migration, diffusion and convection phenomena of the material in the bend to be predicted, and the flow field physical field is used to characterize the flow of the fluid in the bend to be predicted;

[0121] The corrosion rate distribution calculation module is used to calculate the corrosion rate distribution of the elbow to be predicted according to the geometric model provided with the physical field.

[0122] Optionally, in an embodiment, the corrosion rate distribution calculation module includes:

[0123] An initial setting unit, used for acquiring initial conditions of the geometric model provided with a physical field, wherein the initial conditions are used for describing an initial state of the geometric model provided with a physical field;

[0124] A current density calculation unit, used for performing multi-physical field coupling processing on each of the physical fields based on the initial conditions to calculate the current density distribution;

[0125] The corrosion rate calculation unit is used to calculate the corrosion rate distribution of the elbow to be predicted according to the current density distribution.

[0126] Optionally, in an embodiment, the initial conditions include the initial concentrations of each first substance, each of the first substances represents a substance participating in a chemical reaction involved in the flow-accelerated corrosion process in the elbow to be predicted, and the initial concentrations of each first substance are obtained in the following manner: determining the chemical reactions involved in the flow-accelerated corrosion process in the elbow to be predicted; calculating the equilibrium constants corresponding to each chemical reaction based on the environmental information; and calculating the initial concentrations of each first substance based on the equilibrium constants corresponding to each chemical reaction and the equilibrium constant calculation formulas corresponding to each chemical reaction.

[0127] Optionally, in an embodiment, the current density calculation unit includes: a current density calculation subunit, configured to perform multi-physical field coupling processing on each of the physical fields based on the initial conditions, and calculate the current density distribution in combination with the first formula and the second formula;

[0128] The first formula is:

[0129]

[0130] Among them, u i is the electrical mobility of substance i, D i is the molecular diffusion coefficient of substance i, R is the universal gas constant, and T is the fluid temperature;

[0131] The second formula is:

[0132] i a / c =F∑ i z i N i ;

[0133] Among them, i a / c is the anode or cathode current density on the electrode surface, F is the Faraday constant, z i is the charge number of substance i, N i is the total flux of substance i.

[0134] Optionally, in an embodiment, the corrosion rate calculation unit includes:

[0135] The corrosion rate calculation subunit is used to calculate the corrosion rate of each position of the elbow to be predicted according to the current density distribution by using a third formula, and the third formula is:

[0136]

[0137] Among them, V corr is the corrosion rate, M Fe is the molar mass of iron, n is the number of electron transfers in the iron dissolution half-cell reaction, F is the Faraday constant, ρ Fe is the density of iron, i is the local current density;

[0138] The distribution generation subunit is used to obtain the corrosion rate distribution of the bend pipe to be predicted according to the corrosion rates of various positions of the bend pipe to be predicted.

[0139] Optionally, in an embodiment, the flow field physical field is simulated in the following manner: calculating the Reynolds number in the bend to be predicted based on the environmental information; simulating the flow field physical field using a turbulence model or a laminar model based on the Reynolds number in the bend to be predicted.

[0140] Optionally, in an embodiment, the description equation of the physical field of the dilute species transfer is the Nernst-Planck transport equation.

[0141] Embodiment 3

[0142] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a method for predicting the distribution of accelerated corrosion in curved pipe flow as described in Embodiment 1 is implemented.

[0143] Embodiment 4

[0144] This embodiment provides a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions are used to enable a computer to execute a method for predicting accelerated corrosion distribution in curved pipe flow as described in the first embodiment.

[0145] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0146] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for predicting the distribution of accelerated corrosion in elbow flow, characterized in that: include: Acquire pipe bend information and environmental information for the pipe bend to be predicted, wherein the pipe bend information is information describing the material and structure of the pipe bend to be predicted, and the environmental information is information describing the fluid environment in the pipe bend to be predicted; According to the pipe bend information, a geometric model of the pipe bend to be predicted is established; According to the environmental information, the physical field of the geometric model of the bend to be predicted is simulated to obtain a geometric model provided with a physical field, wherein the physical field includes a secondary current distribution physical field, a dilute species transfer physical field and a flow field physical field, wherein the secondary current distribution physical field is used to characterize the distribution of the current on the electrode surface, the dilute species transfer physical field is used to characterize the migration, diffusion and convection phenomena of the substance in the bend to be predicted, and the flow field physical field is used to characterize the flow of the fluid in the bend to be predicted; The corrosion rate distribution of the elbow to be predicted is calculated according to the geometric model provided with the physical field.

2. The method for predicting the distribution of accelerated corrosion in elbow flow according to claim 1, characterized in that: The step of calculating the corrosion rate distribution of the elbow to be predicted according to the geometric model provided with the physical field comprises: Acquire initial conditions of the geometric model provided with a physical field, wherein the initial conditions are used to describe an initial state of the geometric model provided with a physical field; Based on the initial conditions, performing multi-physical field coupling processing on each of the physical fields to calculate the current density distribution; The corrosion rate distribution of the elbow to be predicted is calculated according to the current density distribution.

3. The method for predicting the distribution of accelerated corrosion in elbow flow according to claim 2, characterized in that: The initial conditions include initial concentrations of various first substances, each of which represents a substance participating in a chemical reaction involved in the flow accelerated corrosion process in the elbow to be predicted, and the initial concentrations of various first substances are obtained by: Determining the chemical reactions involved in the flow accelerated corrosion process to be predicted in the elbow; According to the environmental information, respectively calculate the equilibrium constant corresponding to each chemical reaction; The initial concentration of each first substance is calculated according to the equilibrium constant corresponding to each chemical reaction and the equilibrium constant calculation formula corresponding to each chemical reaction.

4. The method for predicting the distribution of accelerated corrosion in elbow flow according to claim 2, characterized in that: Based on the initial conditions, performing multi-physical field coupling processing on each of the physical fields to calculate the current density distribution includes: Based on the initial conditions, multi-physics field coupling processing is performed on each of the physical fields, and the current density distribution is calculated by combining the first formula and the second formula; The first formula is: Among them, u i is the electrical mobility of substance i, D i is the molecular diffusion coefficient of substance i, R is the universal gas constant, and T is the fluid temperature; The second formula is: i a / c =F∑ i z i N i ; Among them, i a / c is the anode or cathode current density on the electrode surface, F is the Faraday constant, z i is the charge number of substance i, N i is the total flux of substance i.

5. The method for predicting the distribution of accelerated corrosion in elbow flow according to claim 2, characterized in that: The step of calculating the corrosion rate distribution of the elbow to be predicted according to the current density distribution includes: According to the current density distribution, the corrosion rate of each position of the elbow to be predicted is calculated by a third formula, and the third formula is: Among them, V corr is the corrosion rate, M Fe is the molar mass of iron, n is the number of electron transfers in the iron dissolution half-cell reaction, F is the Faraday constant, ρ Fe is the density of iron, i is the local current density; According to the corrosion rates of various positions of the bend pipe to be predicted, the corrosion rate distribution of the bend pipe to be predicted is obtained.

6. The method for predicting the distribution of accelerated corrosion in elbow flow according to claim 1, characterized in that: The flow physics is simulated in the following way: Calculating the Reynolds number in the bend to be predicted according to the environmental information; According to the Reynolds number in the curved pipe to be predicted, the physical field of the flow field is simulated by using a turbulence model or a laminar flow model.

7. The method for predicting the distribution of accelerated corrosion in elbow flow according to claim 1, characterized in that: The description equation of the physical field of the dilute species transfer is the Nernst-Planck transport equation.

8. A prediction system for accelerated corrosion distribution in curved pipe flow, characterized in that: include: An information acquisition module, used to acquire the bend information and environmental information of the bend to be predicted, wherein the bend information is information describing the material and structure of the bend to be predicted, and the environmental information is information describing the fluid environment in the bend to be predicted; A model building module, used to build a geometric model of the bend to be predicted according to the bend information; A physical field setting module, used to simulate the physical field of the geometric model of the bend to be predicted according to the environmental information, and obtain a geometric model provided with a physical field, wherein the physical field includes a secondary current distribution physical field, a dilute material transfer physical field and a flow field physical field, wherein the secondary current distribution physical field is used to characterize the distribution of the current on the electrode surface, the dilute material transfer physical field is used to characterize the migration, diffusion and convection phenomena of the material in the bend to be predicted, and the flow field physical field is used to characterize the flow of the fluid in the bend to be predicted; The corrosion rate distribution calculation module is used to calculate the corrosion rate distribution of the elbow to be predicted according to the geometric model provided with the physical field.

9. An electronic device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a method for predicting the distribution of accelerated corrosion in elbow flow as claimed in any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium storing computer instructions, characterized in that: The computer instructions are used to enable a computer to execute a method for predicting the distribution of accelerated corrosion in curved pipe flow as described in any one of claims 1 to 7.

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