A method for predicting the dodecamer content in a test asphalt molecule
By establishing a 12-molecule basic macroscopic property matrix and optimizing the calculation model, the gap in the prediction of the 12-molecule content of asphalt molecules in the existing technology has been filled, realizing rapid and accurate molecular dynamics simulation of asphalt and improving the accuracy of the simulation.
Patent Information
- Application Number
- CN202311486333.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-09
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2043-11-09
AI Technical Summary
Current technology has not been able to effectively predict the content of twelve molecules in asphalt molecules, resulting in insufficient accuracy in asphalt molecular dynamics simulation.
By establishing a 12-molecule basic macroscopic property matrix, drawing molecular structures using chemical engineering software, and combining the principles of normal distribution and Shannon entropy, the calculation model was optimized to determine the content of the 12 molecules, including the composition of saturated fractions, aromatic fractions, polar aromatic fractions, and asphaltenes.
This method enables rapid and accurate determination of the content of twelve molecules in asphalt molecules, saving experimental time and improving the accuracy of asphalt molecular dynamics simulation.
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Figure CN117524324B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of petroleum chemical industry, and particularly relates to a method for predicting the content of twelve molecules in a to-be-detected asphalt molecule. BACKGROUND
[0002] Asphalt is a highly complex material, mainly derived from the by-products of crude oil distillation, and is widely used as a binder for road pavement. In asphalt molecules, there are millions of different molecules, and the properties of an asphalt depend on the content of these polar or non-polar molecules, large or small molecules, and the properties of the asphalt determine the application of such asphalt in various aspects. Therefore, determining the content of polar or non-polar molecules, large or small molecules in asphalt molecules can predict and analyze the basic properties of asphalt. In the literature “Tian Wang, Qin Kang, Hu Yuanchong, et al. Research progress of petroleum molecular reconstruction technology [J]. Journal of Petroleum Science and Technology (Petroleum Processing), 2022, 38(02): 449-466”, the reconstruction method of petroleum molecules is introduced, including deterministic methods such as structure-oriented lumping method, structure unit coupling atom topological matrix method, and molecular homologous matrix method; and stochastic methods such as random reconstruction method, maximum information entropy method, and random reconstruction-maximum information entropy method. The basic idea of molecular reconstruction is to establish a bottom molecular library, introduce the macroscopic properties of the to-be-detected molecule as a constraint condition, optimize the solution of the objective function, and obtain the molecular composition under the optimal solution.
[0003] At present, the twelve-molecule model of asphalt can well characterize the basic properties of asphalt. Specifically, it is divided into saturated molecules (S): squalane (Squalane), hopane (Hopane); aromatic molecules (Ar): perhydrophenanthrene-naphthalene (PHPN), dioctylcyclohexane-naphthalene (DOCHN); polar aromatic molecules (R): quinolinohopane, thio-isorenieratane, benzobisbenzothiophene, pyridinohopane, trimethylbenzene-oxane; asphaltene (At): asphaltene-phenol, asphaltene-pyrrole, asphaltene-thiophene. The twelve-molecule model of asphalt is used for molecular dynamics simulation of asphalt properties, and good results are obtained. According to the macroscopic properties of a specific asphalt molecule, different asphalt molecules are formed by using different proportions of twelve molecules, and the proportion of twelve molecules can be used to accurately and quickly establish an asphalt molecule model, and then perform molecular dynamics simulation on the asphalt molecule. However, there is currently no method for predicting the content of twelve molecules in asphalt molecules. SUMMARY
[0004] In view of the blank of the prior art, the purpose of the present application is to establish a more accurate and conditional asphalt twelve-molecule model by predicting the content of each molecule in the asphalt twelve-molecule model, so that the asphalt molecules can be simulated more accurately.
[0005] The technical scheme of the present application is as follows: a method for predicting the content of twelve molecules in a to-be-tested asphalt molecule, specifically comprising the following steps:
[0006] According to the experimental test method, the content of four components in the to-be-tested asphalt molecule is determined, and the structure and basic properties of the twelve molecules are calculated and drawn according to the chemical software;
[0007] According to the twelve-molecule structure and basic properties of the to-be-tested asphalt molecule and the preset calculation model, the molecular content of the twelve molecules in the to-be-tested asphalt molecule is calculated;
[0008] The preset calculation model calculation process includes:
[0009] Construction of the twelve-molecule basic macroscopic property matrix; according to the twelve-molecule structure and basic properties, a twelve-molecule basic macroscopic property molecular library is established in the form of a matrix; the molecular structure of the twelve molecules is constructed and drawn by using software, and the drawn molecular structure of the twelve molecules is imported into the chemical software to calculate the basic macroscopic properties of the twelve molecules. The basic properties include molecular weight, boiling point, and the proportion of each element (C, H, S, N, O) in each molecule.
[0010] Relationship between the basic macroscopic properties of the twelve molecules and the properties of the to-be-tested asphalt molecule; the mapping relationship between the basic macroscopic properties of the twelve molecules and the macroscopic properties of the to-be-tested asphalt molecule is established by using the mixing rule;
[0011] Preliminary determination of the content of the twelve molecules; the sum of the squares of the differences between the macroscopic property test values of the to-be-tested asphalt molecule and the simulation values of the calculation model is taken as the objective function, the calculation model is continuously optimized for the content parameters of each component, and the preliminary content distribution of the twelve molecules is obtained;
[0012] Adjustment of the final molecular content; under certain constraints, the Shannon entropy principle is taken as the objective function to adjust and optimize the molecular content of the twelve molecules, and the final content distribution of the twelve molecules is obtained.
[0013] The twelve molecules include: saturated molecules S: squalane, hopane; aromatic molecules Ar: perhydrophenanthrene-naphthalene, dioctylcyclohexane-naphthalene; polar aromatic molecules R: quinoline amino hopane, thioisocyanopentane, benzodibenzothiophene, pyridine hopane, trimethylphenoxane; asphalt At: asphalt-phenol, asphalt-pyrrole, asphalt-thiophene.
[0014] The macroscopic physical properties of the asphalt molecules to be measured include molecular weight, boiling point, elemental content, and four-component content.
[0015] In the calculation model, first, the probability density of the boiling points of the twelve molecules is calculated using a normal distribution, and after normalization of the results, the initial twelve-molecule content is obtained, the calculation model simulation value includes the twelve-molecule simulation value, and the specific calculation formula is as follows:
[0016]
[0017]
[0018] wherein x j is the physical property value of the jth molecule conforming to the normal distribution, p j is the probability density of the jth molecule; sigma j and mu j respectively represent the standard deviation and mean value of the jth molecule; y j represents the mass fraction of the jth molecule after p j normalization; J represents twelve molecules; and the physical property value x is the boiling point value of the corresponding molecule.
[0019] The objective function is as follows:
[0020]
[0021] wherein obj is the objective function, I is the four components of asphalt, Y i exp is the actual test value of the four-component content of asphalt, Y i is the calculation simulation value of the four-component content of asphalt;
[0022] The mass fraction corresponding to the twelve molecules and the corresponding standard deviation and mean value are solved by the following objective function.
[0023] The objective function and the constraint condition are as follows:
[0024]
[0025]
[0026] P n = F(a)
[0027] In the formula, E represents the Shannon entropy, N is the number of twelve molecules, a i is the mass fraction of the ith molecule; P n is the actual measurement value of the property n of the asphalt molecule, F(x) represents the mixing rule of the property j, and a is the vector of the mass fraction a i .
[0028] Further, the macro-physical property determination method of the asphalt molecules to be measured is as follows: according to the petroleum and chemical industry standard-petroleum asphalt four-component determination method (NB / SH / T 0509-2010), the four-component (saturated component, aromatic component, resin, asphaltene) content of the asphalt to be measured is tested to obtain the content of the four components; the element content of the asphalt to be measured is tested by using the element analysis method to obtain the corresponding element content.
[0029] By the method for predicting the content of the twelve molecules in the asphalt molecules described in the present application, the related basic physical properties of the twelve molecules can be calculated by using the chemical software, all the obtained properties are sorted and summarized, the residual sum of squares of the actual measurement value and the simulation calculation value of the asphalt four-component content is taken as the objective function after introducing the normal distribution, the boiling point of the twelve molecules is calculated to obtain the preliminary distribution probability of the twelve molecules, and the corresponding mass fraction is obtained after normalization. Subsequently, the Shannon entropy criterion is taken as the objective function, the actual test value and the simulation calculation value of the element content of the asphalt are taken as the constraint condition, the mass fraction of the twelve molecules is further adjusted, and the composition content of the twelve molecules in the asphalt molecules to be measured is calculated after normalization of the result.
[0030] The present application has the following advantages: the method for predicting the content of the twelve molecules in the asphalt molecules to be measured gradually and accurately determines the content of the twelve molecules representing the asphalt molecules in the asphalt to be measured by taking the minimum deviation of the SARA content and the element content as the objective function through the normal distribution and the entropy maximum model on the premise that the SARA content and the element (C, N, O, H, S) content of the asphalt to be measured are known. Through the calculation model of the present application, the content of the twelve molecules in different asphalts to be measured can be quickly and accurately determined, and the first-order physical properties (such as density, viscosity, etc.) of the asphalt to be measured can be simulated more quickly, thereby saving the time and equipment loss of actual experiments. BRIEF DESCRIPTION OF DRAWINGS
[0031] Figure 1 It is the method flow chart for predicting the content of the twelve molecules in the asphalt molecules to be measured provided by the embodiment of the present application.
[0032] Figure 2 It is the four-component content value of the asphalt to be measured actually tested in the embodiment of the present application, and the simulation calculation value after the calculation model processing.
[0033] Figure 3 It is the simulation value of the mass fraction distribution of the twelve molecules in the asphalt to be measured in the embodiment of the present application.
[0034] Figure 4 It is the actual test value and the simulation value obtained by the calculation model of the element (C, N, O, H, S) content of the asphalt to be measured in the embodiment of the present application. Detailed Implementation
[0035] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0036] Figure 1 This is a flowchart of a method for predicting the content of twelve molecules in asphalt molecules according to an embodiment of the present invention. Figure 1 As shown, the entire prediction process includes: first, establishing a basic molecular library of twelve molecules that can represent asphalt molecules; based on the content of the four components of the asphalt to be tested, calculating the distribution probability of the twelve molecules by introducing a normal distribution, and obtaining the preliminary mass fraction of the twelve molecules after normalization; using the macroscopic properties of the asphalt to be tested as constraints, adjusting the mass fraction of the twelve molecules using the Shannon entropy criterion, and calculating the optimal mass fraction of the twelve molecules in the final asphalt molecules to be tested.
[0037] The following content explains the constructed computational models, mainly including the computational model for calculating the initial twelve molecular mass fraction, and the computational model for adjusting the molecular mass fraction using the Shannon entropy criterion.
[0038] First, chemical engineering software was used to calculate the physical properties of the twelve molecules. The obtained physical property values, including boiling point, molecular weight, and elemental composition of each molecule, were then organized and summarized. Using the boiling point of the twelve molecules as input, a normal distribution was introduced. The sum of the squares of the differences between the actual tested content values of the four components and the calculated simulated content values of the four components in the asphalt was used as the objective function. A genetic algorithm was used to optimize the objective function by minimizing it, while simultaneously optimizing the parameters of the normal distribution. After obtaining the minimum objective function, the probability density of the twelve molecules under the optimal parameters was obtained. After normalization, a preliminary mass fraction was obtained. The relevant formulas are as follows:
[0039]
[0040]
[0041] Where, x j Let p be the property value of the j-th molecule that follows a normal distribution. j Let σ be the probability density of the j-th molecule. j and μ j Let and represent the standard deviation and mean of the j-th molecule, respectively. In the formula, y j Indicates to perform p j The mass fraction of the j-th molecule after normalization. J represents twelve molecules.
[0042]
[0043] Wherein, obj is the objective function, I is the four components (saturates, aromatics, resins, asphaltenes) of asphalt, Y i exp is the actual test value of the four components of asphalt, Y i is the calculated simulation value of the four components of asphalt.
[0044] After the preliminary mass fraction of the twelve molecules obtained by the above calculation model, the mass fraction of the twelve molecules is taken as the input value, the Shannon entropy criterion is taken as the objective function, and the element composition of the asphalt to be tested is taken as the constraint condition. The maximum value of the Shannon entropy criterion is optimized under the condition of meeting the constraint condition, and the maximum value of the Shannon entropy criterion is obtained. The mass fraction of the twelve molecules under this condition is output, which is the optimal mass fraction of the twelve molecules. The formula involved is as follows:
[0045]
[0046]
[0047] P n =F(a)
[0048] In the formula, E represents the Shannon entropy, N is the number of twelve molecules, a i is the mass fraction of the i th molecule; P n is the actual measurement value of the property n of the asphalt molecule, F(x) represents the mixing rule of the property j, and a is the vector of the mass fraction a i .
[0049] Figure 2 is the four component content value actually tested in the asphalt to be tested in the embodiment of the application, and the simulation calculation value after the calculation model processing. As can be seen from the figure, the actual test values of the four components of the asphalt to be tested are 11.1, 33.2, 38.9 and 16.8%, respectively. The simulation calculation values of the four components of the asphalt to be tested obtained after calculation by the calculation model are 11.0, 33.2, 38.9 and 16.9%, respectively. The error is within ±1%, and the error range is small. Figure 3 is the simulation value of the mass fraction distribution of the twelve molecules in the asphalt to be tested in the embodiment of the application.
[0050] Figure 4 is the actual test value of the element (C, H, N, O, S) content of the asphalt to be tested in the embodiment of the application and the simulation value obtained by the calculation model. As can be seen from the figure, Figure 4 the element content calculated by the calculation model is very close to the actual test value of the asphalt to be tested, wherein the test values of C, H, N, O and S are 84.9, 8.99, 0.51, 0.8 and 5.56%, respectively. The actual test values of the elements of the asphalt to be tested are not much different. Combined with Figures 2-4Comprehensively considering, the calculation model for predicting the content of 12 molecules in the asphalt molecules designed and built in the application has relatively accurate calculation accuracy, and this also creates a good foundation for the molecular dynamics simulation of the asphalt molecules.
Claims
1. A method for predicting the content of twelve molecules in a sample of asphalt, characterized in that, Specifically comprising the following steps: According to the experimental test method, the content of the four components in the asphalt molecule to be tested is determined, and the twelve molecular structures and basic properties are calculated according to the chemical software; According to the twelve molecular structures and basic properties of the asphalt molecule to be tested and the preset calculation model, the molecular content of the twelve molecules in the asphalt molecule to be tested is calculated; The preset calculation model calculation process includes: Construction of the twelve molecular basic macroscopic property matrix; according to the twelve molecular structure and basic property, the basic macroscopic property molecular library of the twelve molecules is established in the form of a matrix; Obtaining the relationship between the twelve molecular basic macroscopic property and the property of the asphalt molecule to be tested; the mapping relationship between the basic macroscopic property of the twelve molecules and the macroscopic property of the asphalt molecule to be tested is established by using the mixing rule; Preliminary determination of the twelve molecular content; the sum of squares of the difference between the test value and the calculation model simulation value of the macroscopic property of the asphalt molecule to be tested is taken as the objective function, the calculation model is continuously optimized, and the preliminary content distribution of the twelve molecules is obtained; Adjustment of the final molecular content; under certain constraint conditions, the objective function is constructed by using the Shannon entropy criterion, the molecular content of the twelve molecules is adjusted and optimized, and the final content distribution of the twelve molecules is obtained; the macroscopic property of the asphalt molecule to be tested includes molecular weight, boiling point, element content and four component content; the calculation model simulation value includes the simulation value of the twelve molecules, and the relationship is as follows: wherein x j is the property value of the jth molecule conforming to a normal distribution, p j is the probability density of the jth molecule; σ j and μ j respectively represent the standard deviation and mean value of the jth molecule; y j represents the mass fraction of the jth molecule after p j normalization; J represents twelve molecules; the property value x is the boiling point value of the corresponding molecule; The objective function and the constraint condition are as follows: P n = F(a) where E represents the Shannon entropy, N is the number of dodecanes, a i is the mass fraction of the i-th molecule; P n is the actual measured value of the property n of the asphalt molecules, F(x) represents the mixing rule for the property j, a is the mass fraction a i is the vector of the mass fractions a.
2. The method for predicting the content of dodecamers in a sample of bitumen according to claim 1, characterized in that, The objective function is as follows: wherein obj is the objective function, I is the asphalt four-component, is the actual test value of the asphalt four-component content, Y i is the calculated simulation value of the asphalt four-component content; The preliminary mass fraction corresponding to the twelve molecules in the asphalt molecule to be tested and the corresponding standard deviation and mean value are solved by the above objective function.