A method for predicting the carbon-hydrogen ratio of oil products from average boiling point and specific gravity

Abstract

The present invention discloses a method for predicting the carbon-hydrogen ratio of oil products based on average boiling point and specific gravity. The method comprises the following steps: using a temperature parameter derived from the average boiling point and a density parameter derived from the specific gravity to regress and establish a formula for estimating the carbon-hydrogen ratio of a petroleum fraction; modifying the regression formula to obtain a carbon-hydrogen ratio model for the petroleum fraction; performing a goodness-of-fit test on the model; and establishing a method for estimating the carbon-hydrogen ratio of the petroleum fraction. The estimation method provided by the present invention establishes a carbon-hydrogen ratio estimation model for the petroleum fraction, predicts unknown carbon-hydrogen ratio properties of the petroleum fraction, and provides highly accurate estimation results. The method is applicable to fields such as oil product carbon-hydrogen ratio estimation, process simulation and optimization calculations, and device product quality inspection.

Description

Technical Field

[0001] The present invention is applicable to the fields of chemical engineering calculation, chemical design, and chemical production, and particularly relates to a method for estimating the carbon-to-hydrogen ratio of petroleum fractions. The calculated carbon-to-hydrogen ratio is an important property for characterizing the composition of petroleum products. This property is mainly used in petrochemical production, process simulation, and simulation calculation. Background Art

[0002] The carbon-hydrogen ratio of petroleum fractions is a basic property of petroleum substances. The carbon-hydrogen ratio is used to characterize the composition of petroleum fractions or the type of hydrocarbons. Based on experimental data, the American Petroleum Institute (API) manual provides a nomogram for estimating certain difficult-to-measure properties from easily measurable properties such as density, boiling point, and Reiter vapor pressure. From an application point of view, the average boiling point and density of petroleum fractions are the two most commonly used and easiest to obtain properties. In order to facilitate computer applications, researchers have proposed mathematical correlation expressions corresponding to the above nomograms. Riazi et al. conducted in-depth research on the estimation of the carbon-hydrogen ratio of petroleum fractions and proposed multiple correlation formulas for estimating the CH ratio from the two properties of average boiling point and density. The specific expression is:

[0003] CH=3.4707[exp(0.01485Tb+16.94SG-0.012492TbSG)]Tb -2.2725 SG -6.798

[0004] CH = 8.7743 × 10 -10 [exp(0.007176Tb+30.06242SG-0.00735TbSG)]Tb -0.98445 SG -18.2753

[0005] However, the estimated correlation formula given by Riazi et al. cannot cover the application range of the Winn nomogram in the API manual, and as the boiling point of the distillate increases, the calculated carbon-hydrogen ratio will increase sharply (>30) and lose its physical meaning.

[0006] The carbon-to-hydrogen ratio of petroleum fractions is widely used in petroleum refining engineering calculations and is therefore essential in petroleum-related chemical design, production, and scientific research. The reliability of the carbon-to-hydrogen ratio of petroleum fractions largely determines the reliability of petroleum refining engineering calculations and process simulations.

[0007] During oil production, real-time monitoring of oil properties is the most direct way to ensure production safety and maintain oil quality stability. While much measured crude oil data exists for the complex composition of petroleum fractions, it remains insufficient compared to the variety of oils used in industry and research. With the advancement of production and scientific research, petroleum fractions with unmeasured carbon-to-hydrogen ratios are often encountered, requiring estimation.

[0008] Early methods for estimating the C / H ratio of petroleum fractions mostly relied on simple mathematical models. While these methods were simple and easy to use, they lacked sufficient raw data, resulting in crude regression methods and the lack of interaction between variables. Estimating the C / H ratio of petroleum fractions relied solely on empirical methods based on weighted summation of variables. This was highly empirical, and different estimation formulas had varying scopes of application. This resulted in low precision and accuracy for some petroleum fractions. Currently, existing C / H ratio estimation models still exhibit significant errors in their calculations, making them difficult to meet practical estimation needs given the increasing variety of oils. To overcome these shortcomings, a simpler and more accurate C / H ratio estimation model is needed. The proposed new method surpasses previous methods in that it yields more accurate C / H ratio estimates, is simple and clear, and has a wide range of applicability.

[0009] Therefore, to solve the above problems, the present invention provides a method for predicting the carbon-hydrogen ratio properties of oil products based on average boiling point and specific gravity. Based on the idea of ​​multiple linear regression of the QSPR model, the regression equation is solved using the standard differential evolution algorithm and the quasi-Newton method to obtain a theoretical model for predicting the carbon-hydrogen ratio of petroleum fractions. This model is easy to use, has accurate prediction calculations, and has a wide range of applications. It is not limited by the increase in the boiling point of the fraction and is an innovative invention in this field. Summary of the Invention

[0010] In light of this, the present invention provides a method for predicting the C / H ratio of oil products from their average boiling point and specific gravity. This method uses analytical fitting based on the physical properties of petroleum fractions, namely their specific gravity and average boiling point, to establish a C / H ratio estimation model for pure substances and petroleum fractions. This method can be used to predict unknown C / H ratios of petroleum fractions, resulting in a simpler estimation process and unique results.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A method for predicting the carbon-hydrogen ratio of oil products based on average boiling point and specific gravity comprises the following steps:

[0013] S1, the average boiling point estimated from the distillation curve is used as the temperature parameter, and the specific gravity is measured or estimated as the density parameter.

[0014] S2, establish the correlation equation for estimating the carbon-hydrogen ratio of petroleum fractions through regression;

[0015] S3. Collect experimental data, obtain the regression equation of the average boiling point and specific gravity against the carbon-hydrogen ratio, and get the carbon-hydrogen ratio estimation model;

[0016] S4. Use the iterative method to solve the corrected estimated value;

[0017] S5. Model goodness-of-fit test;

[0018] S6. Establish an estimation method for the carbon-hydrogen ratio of petroleum fractions.

[0019] Preferably, in step S1 for establishing the carbon-hydrogen ratio prediction formula of petroleum fractions, first, the temperature parameter correlation formula obtained from the average boiling point and the density parameter correlation formula obtained from the specific gravity are as follows:

[0020] (1) The temperature parameter correlation formula obtained from the average boiling point:

[0021] When 80 < T < 120 °F,

[0022] T B = 0.3145481T - 0.0002288668T 2 + 7.861313×10 -8 T 3 + 5.389785×10 -11 T 4

[0023] (2) The density parameter correlation formula obtained from the specific gravity:

[0024] When 0.65 < SG < 1.08,

[0025] G = -1817.526SG + 1759.23SG 2 - 959.6614SG 3 - 207.2923SG 4 + 3.739379SG 5 .

[0026] Preferably, in step S3 for establishing the carbon-hydrogen ratio estimation formula of petroleum fractions, the established carbon-hydrogen ratio estimation correlation formula is as follows:

[0027] (1) Obtain the iterative variable:

[0028] A = 0.001148822G + 0.8672727

[0029] B = 0.02975209G - 29.85887

[0030] C = -3.271484G + T B + 396.371

[0031] D = -1.16741G + 272.5885

[0032] (2) Iteration process:

[0033] Take the value of X = 16.0 - 0.03T B -0.08G

[0034] As the initial value,

[0035] If

[0036] ΔX = (-2BX - 3AX 2 - D) / (-AX 2 - BX 2 - DX + C) > 0.001,

[0037] Then X = X - ΔX, repeat this step;

[0038] If ΔX = (-2BX - 3AX 2 - D) / (-AX 2 - BX 2 - DX + C) < 0.001,

[0039] Then X is the result. This result can be verified.

[0040] In the formula: T is the average boiling point of the petroleum fraction, in °F; SG is the specific gravity of the petroleum fraction, 60°F / 60°F; T B is the temperature parameter obtained by correlating the average boiling point of the petroleum fraction, in °F; G is the density parameter obtained by correlating the specific gravity of the petroleum fraction, 60°F / 60°F.

[0041] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​G=-1817.526SG+1759.23SG 2 -959.6614SG 3 -207.2923SG 4 +3.739379SG 5

[0048] (3) Obtain the iteration variable:

[0049] A=0.001148822G+0.8672727

[0050] B=0.02975209G-29.85887

[0051] C=-3.271484G+T B +396.371

[0052] D=-1.16741G+272.5885

[0053] (4) Iterative process:

[0054] Value X = 16.0-0.03T B -0.08G

[0055] As the initial value,

[0056] like

[0057] ΔX=(-2BX-3AX 2 -D) / (-AX 2 -BX 2 -DX+C)>0.001,

[0058] Then X = X - ΔX, repeat this step;

[0059] If ΔX=(-2BX-3AX 2 -D) / (-AX 2 -BX 2 -DX+C)<0.001,

[0060] Then X is the result. This result can be tested.

[0061] Where: T is the average boiling point of the petroleum fraction, in °F; SG is the specific gravity of the petroleum fraction, 60°F / 60°F; T B is the temperature parameter of the petroleum fraction related to the average boiling point, the unit is ℉; G is the density parameter of the petroleum fraction related to the specific gravity, 60℉ / 60℉.

[0062] Preferably, the estimation model in step S3 uses the idea of ​​multiple linear regression to establish a quantitative functional relationship between the two structural parameters and the carbon-hydrogen ratio, thereby obtaining a theoretical model for predicting the carbon-hydrogen ratio of petroleum fractions.

[0063] Preferably, in step S3, a regression equation is established based on the actual oil physical property data.

[0064] Preferably, in step S3, the regression equation is solved using a standard differential evolution algorithm and a quasi-Newton method to obtain a theoretical model for predicting the carbon-hydrogen ratio of petroleum fractions.

[0065] Preferably, in step S4, an iterative method is used to solve the revised estimated value, and the optimal value is solved in an iterative manner in combination with the idea of ​​multiple linear regression of the pure component QSPR model.

[0066] When taking the initial value of the carbon-hydrogen ratio, the method of proportional correlation with the parameters of the average boiling point and specific gravity after fitting correction is adopted.

[0067] CH0=16-0.03MeABP-0.08SG

[0068] The iterative relationship is as follows:

[0069] ΔCH=k1-k2+1.17G-272.59=0

[0070] k1=(0.06G-59.72)×(16-0.03T B -0.08G)

[0071] k2=(0.003G+2.61)×(16-0.03T B -0.08G) 2

[0072] Where k1 and k2 are parameter variables obtained from known variables.

[0073] The iteration criterion is:

[0074]

[0075] When the iteration criterion ΔCH < 0.001, the iteration is stopped. By simplifying, the calculation formula of the carbon-hydrogen ratio can be obtained as follows:

[0076]

[0077] The applicable range of this method is: average boiling point 336.48K-866.48K, specific gravity 0.65-1.08.

[0078] Preferably, in step S5, the specific implementation of the model goodness test is as follows:

[0079] This method is compared with the experimental data of the carbon-hydrogen ratio of petroleum fractions in the literature to determine the estimation accuracy and estimation range of the prediction model; this method predicts the carbon-hydrogen ratio physical properties of actual oil products that do not participate in the regression model to test the estimation accuracy and prediction ability of the model.

[0080] Compared with the prior art, the present invention has the following beneficial effects:

[0081] The present invention proposes a method for predicting the carbon-hydrogen ratio properties of oil products by using average boiling point and specific gravity. The method is easy to use, simple in form, has easy-to-obtain parameters, a wide range of applications, a simple and clear model, does not require complex network training of pure components, and has low algorithm complexity. It is particularly suitable for situations where the amount of data is small and training is difficult. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0083] Figure 1 This is a flow chart of a method for predicting the carbon-hydrogen ratio of oil products based on average boiling point and specific gravity according to the present invention;

[0084] Figure 2 This is a flow chart for estimating the carbon-hydrogen ratio of oil products based on average boiling point and specific gravity;

[0085] Figure 3 A comparison chart of the new carbon-hydrogen ratio model of the present invention, the estimated values ​​of the Riazi model and the actual values ​​of the oil products;

[0086] Figure 4 This is a diagonal error diagram of the new carbon-hydrogen ratio model of the present invention and the actual value of the oil product. DETAILED DESCRIPTION

[0087] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0088] Example 1:

[0089] Example 1 of the present invention discloses a method for predicting the carbon-hydrogen ratio of oil products based on average boiling point and specific gravity, and the technical solution adopted is as follows:

[0090] Validation of a prediction method for the carbon-hydrogen ratio of oil products

[0091] For example, consider an oil product used in a vacuum process. Its specific gravity is 0.8924, and its average boiling point is 269.53°C. The actual carbon-to-hydrogen ratio is 7.38. The estimated calculation is as follows:

[0092] (1) The specific gravity of the oil is between 0.65 and 1.08, and the average boiling point is between 336.48K and 866.48K. This method can be used to estimate the oil. First, convert the temperature unit:

[0093] MeABP R =1.8MeABP-459.67=517.15°F

[0094] (2) The temperature parameter correlation formula obtained from the average boiling point and the density parameter correlation formula obtained from the specific gravity are:

[0095] T B =0.3145MeABP R -0.0002289MeABP R 2 +7.861×10 -8 MeABP R 3 +

[0096] 5.390×10 -11 MeABP R 4 -4.165×10 -14 MeABP R 5 -19.15=95.50

[0097] G=-908.765SG+879.615SG 2 -479.83SG 3 +103.645SG 4 +1.87SG 5 +421.545=73.71

[0098] Where MeABP is the mean boiling point of the petroleum fraction, in °F; SG is the specific gravity of the petroleum fraction, 60°F / 60°F; T B is the temperature parameter of the petroleum fraction related to the average boiling point, the unit is ℉; G is the density parameter of the petroleum fraction related to the specific gravity, 60℉ / 60℉.

[0099] (3) Enter the iterative process and calculate the initial value and correlation coefficient required for iteration. As follows:

[0100] CH0=16-0.03T B -0.08G=7.24

[0101] A=0.0011*G+0.86=0.95

[0102] B=0.03G-29.85=-27.67

[0103] C=-3.27G+T B +396.37=250.71

[0104] D=1.17G+272.59=186.53

[0105] Start the iterative process, and the iterative criterion obtained by the first calculation is:

[0106]

[0107] get

[0108]

[0109] The second calculation results in the iterative criterion:

[0110]

[0111] get

[0112]

[0113] The third calculation results in the iterative criterion:

[0114]

[0115] get

[0116]

[0117] And so on. When the iteration criterion ΔCH < 0.001, the iteration is stopped. By simplifying, the calculation formula of the aniline point can be obtained, where n represents the number of iterations. The calculation formula is:

[0118]

[0119] Where CH represents the predicted carbon-hydrogen ratio, and n represents the number of iterations. Compared to the measured value of 7.38, the relative error of this method is 0.33%. Similarly, the measured and estimated values ​​for 10 other real oil products can be verified. The error analysis results are shown in the following table:

[0120] Table 1 Relative error between the estimated value of the new carbon-hydrogen ratio model of the present invention and the actual value of diesel oil

[0121]

[0122] Table 2 Relative error between the new model estimated value of carbon-hydrogen ratio and the actual value of Tarim oil products

[0123]

[0124] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0125] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for predicting the carbon-hydrogen ratio of oil products from average boiling point and specific gravity, characterized in that: It includes the following steps: S1. Taking the average boiling point in the oil product as the temperature parameter, measure or estimate the specific gravity as the density parameter. S2. Establish the estimation correlation formula of the carbon-hydrogen ratio of petroleum fractions through regression. S3. According to the existing experimental data, the regression equation of the average boiling point and specific gravity on the carbon-hydrogen ratio, obtain the carbon-hydrogen ratio estimation model. S4. Use the iterative method to solve the corrected estimated value. S5. Model goodness-of-fit test. S6. Establish the estimation method of the carbon-hydrogen ratio of petroleum fractions. The temperature parameter correlation formula obtained from the average boiling point and the density parameter correlation formula obtained from the specific gravity in step S1 are as follows: (1) The temperature parameter correlation formula obtained from the average boiling point: When 80 < T < 120 ℉ (2) The density parameter correlation formula obtained from the specific gravity: When 0.65 < SG < 1.08 ； The estimation model in step S3 is as follows: (1) Obtain the iterative variable: (2) Iterative process: Take the value as the initial value. If ， but , repeat this step; like , but For the result; The result can be tested. Where: T is the average boiling point of the petroleum fraction, in °F; SG is the specific gravity of the petroleum fraction, 60°F / 60°F; is the temperature parameter of the petroleum fraction related to the average boiling point, in °F; G is the density parameter of the petroleum fraction related to the specific gravity, 60°F / 60°F; Among them, when taking the initial value of the carbon-hydrogen ratio, a method proportional to the parameters of the average boiling point and specific gravity after fitting and correction is adopted. The iterative relation formula is as follows: in k 1 ，k 2 is the parameter variable obtained from the known variables. The iterative criterion is: When the iteration criterion When , the iteration stops; by simplifying, the calculation formula of the carbon-hydrogen ratio can be obtained as follows: At this time, CH obtained is the carbon-hydrogen ratio. The applicable range of this method: the average boiling point is 336.48K - 866.48K, and the specific gravity is 0.65 - 1.

08.

2. The method for estimating the carbon-hydrogen ratio of petroleum fractions according to claim 1, characterized in that: The estimation model in step S3 uses the idea of multiple linear regression to establish the quantitative functional relationship between the two structural parameters of the average boiling point and specific gravity and the carbon-hydrogen ratio, and obtains the theoretical model for predicting the carbon-hydrogen ratio of petroleum fractions.

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