Method for determining concentration of amine in desulfurized amine solution through near infrared spectrum, storage medium and equipment

Abstract

The invention provides a method for determining the concentration of amine in desulfurization amine liquid through near infrared spectroscopy, a storage medium and equipment, and the method comprises the following steps: adopting desulfurization amine liquid samples with different concentrations, determining the concentration of amine in the samples through a standard method, determining the near infrared spectroscopy of the samples, taking a 4000-6000 cm <-1 > spectrum interval as a characteristic spectrum area, and calculating the concentration of amine in the desulfurization amine liquid through a standard method. Carrying out second-order differential treatment on the characteristic spectrum region, correlating the absorbance of the obtained characteristic spectrum with the amine concentration measured by a standard method, carrying out regression analysis, establishing a correction model, then measuring the near infrared spectrum of a sample to be measured, carrying out second-order differential treatment on a spectrogram, and taking a 4000-6000 cm <-1 > spectrum region as the characteristic spectrum region; and substituting the absorbance of the characteristic spectrum region into the correction model to obtain the amine concentration of the to-be-detected sample. By adopting the method, the concentration of amine in the desulfurized amine liquid can be quickly predicted, the operation is simple, the analysis speed is high, the prediction is accurate, and the analysis operation environment can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical testing, and in particular relates to a method for measuring the concentration of amines in a desulfurization amine solution using near-infrared spectroscopy, a storage medium and a device. Background Art

[0002] With the development of oil refining technology, the desulfurization of refinery gas and petroleum products has become one of the key points of refining enterprises. Due to the continuous increase in the ratio of residual oil blending, the sulfur content of refinery gas has increased rapidly. Most refineries use the amine desulfurization hydrogen sulfide (H2S) process with better desulfurization effect. This process generally uses alcohol amine desulfurizers. During the production process, the amine concentration in the desulfurization liquid must have strict control indicators. Too low or too high will cause the sulfur content in the liquefied gas to be unqualified or the liquefied gas to be lost, so strict control and verification are required.

[0003] The desulfurization amine solution contains desulfurizer (such as methyldiethanolamine), water, sulfides such as hydrogen sulfide and ferrous sulfide, carbon dioxide, hydrocarbon gas, oil, heat-stable salt and solid debris. The sample is dirty and smelly, dark in color and complex in composition. The current common methods for determining the concentration of amines in desulfurization amine solution are oil non-aqueous titration method and chromatography. The former is troublesome to operate manually and takes a long time to analyze, which takes 1 hour. The latter is simpler to analyze, but N-methyldiethanolamine is an alkaline substance, and the chromatographic column is severely adsorbed, easily fails, and the analysis repeatability is poor.

[0004] In order to shorten the analysis time, improve the analysis efficiency and improve the analysis and detection environment, it is necessary to develop an analysis method for the amine concentration in the desulfurization amine solution. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present invention proposes a method for measuring the amine concentration in a desulfurization amine solution by near infrared spectroscopy, a storage medium and a device.

[0006] In a first aspect, the present invention provides a method for measuring the concentration of amines in a desulfurization amine solution by near infrared spectroscopy, comprising the following steps:

[0007] S1: Use different concentrations of desulfurization amine solution samples and determine the amine concentration of the samples using the standard method.

[0008] S2: measuring the near infrared spectra of the desulfurization amine solution samples of different concentrations in step S1, selecting characteristic spectral regions for second-order differential processing, and obtaining the absorbance of the desulfurization amine solution samples of different concentrations;

[0009] S3: Correlate the absorbance of the desulfurization amine solution samples of different concentrations obtained in step S2 with the amine concentrations of the desulfurization amine solution samples of different concentrations obtained in step S1, perform regression analysis, and establish a calibration model for the test amine concentration.

[0010] S4: measuring the near infrared spectrum of the sample to be tested, selecting the characteristic spectrum for second-order differential processing, and obtaining the absorbance of the sample to be tested;

[0011] S5: Substitute the absorbance of the sample to be tested in step S4 into the calibration model obtained in step S3 to obtain the amine concentration of the sample to be tested.

[0012] As a specific embodiment of the present invention, in step S1, the number of desulfurization amine solution samples of different concentrations is not less than 40, preferably not less than 50, more preferably, the number of samples is 50-600, and further preferably, 100-500.

[0013] As a specific embodiment of the present invention, in step S1, the mass fraction range of the amine concentration of the desulfurization amine solution sample is 10.00-50.00%, preferably 25.00-45.00%. More preferably, the amine concentration in the sample is evenly distributed within the possible range.

[0014] As a specific embodiment of the present invention, in step S1, the standard method is titration or chromatography, preferably titration.

[0015] As a specific embodiment of the present invention, in step S2 and step S4, measuring the near-infrared spectrum also includes the same measuring conditions, and the measuring conditions include sample temperature and ambient temperature; preferably, the sample temperature is 20-40°C.

[0016] According to the present invention, when measuring the near-infrared spectrum of the sample, a 0.5 mm quartz cuvette is preferably used, and the sample injection volume is preferably made to reach two-thirds of the volume of the vial. The cuvette containing the sample is sealed and the temperature of the sample is ensured to be the same each time it is measured.

[0017] As a specific embodiment of the present invention, in step S2 and step S4, the interval of the selected characteristic spectrum is 4000-6000cm -1 .

[0018] According to the present invention, if the wavelength range of the near-infrared spectrum is selected too small, the effective information of the oil product may be incomplete, affecting the adaptability of the model; if the wavelength is selected too large, a large amount of noise and invalid information may be introduced, interfering with the stability of the model.

[0019] As a specific implementation of the present invention, in step S2 and step S4, the second-order differential processing of the characteristic spectrum also includes vector normalization and mean centering processing independently.

[0020] As a specific implementation of the present invention, in step S3, the regression analysis includes regression analysis such as partial least squares (PLS), least squares method (CLS), principal component regression (PCR), inverse least squares (ILS) or robust partial least squares (RPLS); preferably partial least squares (PLS).

[0021] Exemplarily, the process of establishing a calibration model using partial least squares method is as follows:

[0022] When the PLS method is used to establish a correction model, the modeling is based on the Beer-Lambert law:

[0023] Y=XB+E,

[0024] In the formula,

[0025] Y—(m×n) absorbance matrix consisting of m samples and n wavelength points;

[0026] X—(m×1) concentration vector consisting of m samples and 1 component;

[0027] B—1 component, (1×n) sensitivity vector consisting of n wavelength points;

[0028] E—m×n absorbance residual matrix.

[0029] The number of wavelength points is the number of information recorded by the spectrometer within a set spectral range.

[0030] The general algorithm for building the calibration model is as follows:

[0031] 1. Perform mean centering on each element of the absorbance matrix Y (the absorbance of the characteristic spectral region obtained after second-order differential processing) and the concentration vector X, that is, subtract the average value of the corresponding data group (column vector) from all data; then perform vector normalization, that is, divide each vector component by the sum of all vector components.

[0032] 2. The normalized absorbance matrix Y and concentration vector X are decomposed into principal components:

[0033]

[0034]

[0035] In formula (1) and (2):

[0036] t k (m×1)—factor score of absorbance matrix, y-score;

[0037] v k (1×n)—factor loading of absorbance matrix, y-loading;

[0038] r k (m×1)—factor score of concentration vector, x-score;

[0039] q k (1×1)—is a number, the factor loading of the concentration vector, x-loading;

[0040] p—number of principal factors;

[0041] E Y —Absorbance matrix residual;

[0042] E X —Concentration vector residual.

[0043] In order to ensure that T obtained from Y can have a good linear relationship with R obtained from X, we can introduce information about R when Y is decomposed into T, or introduce information about T when X is decomposed into R. This can be achieved by exchanging iteration variables during iteration, that is, combining the above two decomposition processes into one, that is,

[0044] r k =b k t k (3)

[0045] b k (1×1)—r k and t k The regression coefficient

[0046] 3. Solve the characteristic vector and the number of main factors p

[0047] Ignoring the residual matrix E, according to equations (1) and (2), when p = 1, we have:

[0048] Y=tv t

[0049] Multiply t on the left t Get: v t =t t Y / t t t

[0050] Multiply the right side by v and we get: t = Yv / v t v

[0051] X=rq

[0052] Multiply left by r t So: q = r t X / r t r, divide both sides by q to get: r = X / q

[0053] [1] Find the weight vector w of the absorbance matrix,

[0054] Take a column of the concentration matrix X as the starting iteration value of r, replace t with r, and calculate the equation for w: Y = rw t The solution is:

[0055] t=Yw / w t w

[0056] [2] Normalized w:

[0057] [3] Find the factor score t of the absorbance matrix, and calculate t from the normalized w

[0058] Equation: Y = tw t The solution is: t = Yw / w t w

[0059] [4] Find the weight u of the concentration vector and use t instead of r to calculate u

[0060] The solution of the equation: X = tu is: u = t t X / t t t

[0061] Find the factor score r of the concentration vector, x-score, and calculate r from u

[0062] The solution of the equation: X = ru is: r = X / u

[0063] Then replace t with this r and return to step [1] to calculate w. t Calculate t 新 , and repeat the iterations until t converges (||t 新 -t 旧 ||≤10 6 ||t 新 ||) continues to the next step, otherwise returns to step [1].

[0064] Calculate the load vector v, y-loading of the absorbance matrix from the converged t

[0065] Equation: Y = tv t The solution is: v t =t t Y / t t t

[0066] Calculate the loading q value of the concentration vector from r, x-loading

[0067] The solution to the equation: X = rq is: q = r t X / r t r

[0068] From this, we can find r1, q1, t1, V1 corresponding to the first principal factor. t

[0069] Substitute into formula (3) to find b1:

[0070] The residual matrix E is calculated by formulas (1) and (2):

[0071] E X,1 =X-r1q1=X-b1t1q1 (4)

[0072] E Y,1 =Y-t1v (5)

[0073] E X,1 Instead of X, E Y,1 Substitute Y and return to step [1] to calculate the next component

[0074] r2,q2,t2, b2

[0075] Calculate E according to formula (4) and (5): X,2 、E Y,2 , and so on, find all the principal factors of X and Y.

[0076] The number of main factors was determined using the interaction test method.

[0077] The method of the invention is to determine the amine concentration of the sample to be tested by using the absorbance of the characteristic spectrum region of the near infrared spectrum of the sample to be tested.

[0078] The near infrared spectrum of the sample to be tested is measured under the same conditions as the modeling method of the present invention, and the spectrum of its characteristic spectrum area is subjected to second-order differential processing, and then the mean center combined vector normalization processing same as the modeling is performed to obtain the absorbance y of the sample to be tested. 待测 , the amine concentration x is determined by calibration mode 待测 , the steps are as follows:

[0079] [1] By y 待测 And the v stored during the calibration process k Calculate t k(待测)

[0080]

[0081] [2] From the obtained t k(待测) and b stored during the calibration process k Calculate r k(待测)

[0082] r k(待测) =b k t k(待测)

[0083] [3] From the obtained r k(待测) and q stored during the calibration process k, use formula (2) to calculate x 待测 .

[0084] In a second aspect, the present invention provides a computer-readable storage medium, wherein a computer program stored in the computer-readable storage medium can be executed by one or more processors to implement the method described in the first aspect.

[0085] In a third aspect, the present invention provides an electronic device comprising a memory and one or more processors, wherein the memory stores a computer program, and the memory and the one or more processors are communicatively connected to each other, and when the computer program is executed by the one or more processors, the method described in the first aspect is performed.

[0086] Compared with the prior art, the present invention has the following beneficial effects:

[0087] The method for measuring the amine concentration in the desulfurization amine solution by near infrared spectroscopy of the present invention relates the absorbance of the characteristic spectrum area of ​​the near infrared spectrum of the sample to the amine concentration of the sample measured by the standard method, establishes a correction model by multivariate regression analysis, and then predicts the amine concentration of the sample to be tested by the absorbance of the sample to be tested in the characteristic spectrum area by the correction model. The method is simple to operate, has a fast analysis speed, can greatly improve the analysis operation environment, and improves the analysis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 is the near infrared spectrum of the typical desulfurization amine solution of the present invention;

[0089] Figure 2 This is a correlation diagram of the near-infrared spectrum predicted values ​​of the amine concentrations of the samples in the validation set using the method of the present invention and the actual measured values ​​using the standard method in the examples of the present invention. DETAILED DESCRIPTION

[0090] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0091] The chemometrics software used in the embodiments of the present invention is the chemometrics software TQ Analyst. The instrument for near infrared spectroscopy is the AntarisⅡ near infrared spectrometer from Thermo Fisher.

[0092] Example

[0093] This embodiment provides a method for measuring the amine concentration in the desulfurization amine solution by near infrared spectroscopy, and the specific details are as follows:

[0094] S1: 289 desulfurization amine liquid samples were collected and their amine concentrations were determined by titration. 226 samples were taken as the calibration set, as shown in Table 1; the amine concentration distribution range was 26.17-43.61m%; the remaining 63 samples were used as the validation set, and the amine concentration distribution range was 27.84-44.72m%; the amine concentrations of the 226 calibration samples determined by titration formed a concentration vector X.

[0095] S2: measuring the near infrared spectra of 289 desulfurization amine solution samples in step S1;

[0096] Fill the sample of desulfurization amine solution to about two-thirds of the position and seal it with sealing film. Put it into the sample pool rack for transmission spectrum collection. The spectrum collection temperature is 25℃ and the collection range is 3500~10000cm -1 , repeated scanning 128 times, with a resolution of 8cm -1 , a total of 289 samples were collected; the near-infrared spectrum of a typical desulfurization amine solution is as follows Figure 1 shown.

[0097] Take 226 calibration samples in the characteristic interval 4000~6000cm -1 The near-infrared spectrum is processed by second-order differentiation, and then vector normalization and mean centering are performed to obtain the absorbance matrix Y.

[0098] S3: Correlate the absorbance matrix Y of the 226 calibration samples obtained in step S2 with the amine concentration vector X of the 226 calibration samples obtained in step S1 using PLS, perform regression analysis, and establish a calibration model for the test amine concentration;

[0099] The number of factors is 12, the root mean square error of the interactive validation is 0.89m%, and the correlation coefficient between the measured and predicted values ​​is 0.976.

[0100] S4: Perform near infrared spectroscopy on the 63 samples in the validation set. -1 The near-infrared spectrum is processed by second-order differentiation, mean centering and vector normalization to obtain the absorbance y of each sample;

[0101] S5: Substitute the absorbance y of the sample to be tested in step S4 into the calibration model obtained in step S3 to obtain a predicted value of the sample amine concentration.

[0102] The predicted values ​​of amine concentrations of validation set samples and the measured values ​​of the standard method are shown in Table 1. The correlation between the predicted values ​​and the measured values ​​of all validation set samples is shown in Figure 2 shown.

[0103] Table 1 Predicted values ​​of sample amine concentration and measured values ​​of standard method

[0104]

[0105]

[0106]

[0107] As can be seen from Table 1, the prediction results of the method of the present invention are moderately better than the measured values ​​of the standard method, the root mean square error of prediction (RMSEP) is 0.47m%, and the correlation coefficient is 0.989.

[0108] In summary, the method of the present invention for determining the amine concentration in the desulfurization amine solution by near-infrared spectroscopy relates the absorbance in the characteristic spectral region of the sample near-infrared spectrum to the amine concentration of the sample determined by the standard method, establishes a calibration model through multivariate regression analysis, and then predicts the amine concentration of the sample to be tested by the absorbance of the sample to be tested in the characteristic spectral region through the calibration model. The method is simple to operate, has a fast analysis speed, can greatly improve the analysis operation environment, and improves the analysis efficiency.

[0109] In addition, it should be understood that the method or system disclosed in the embodiments provided in the present application can also be implemented in other ways. The method or system embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the methods and devices according to the multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a computer program segment or a part of a computer program, and the module, computer program segment or a part of a computer program contains one or more computer programs for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings, and can actually be executed in parallel. They can also be executed in the opposite order sometimes, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs the specified function or action, or can be implemented with a combination of dedicated hardware and computer programs.

[0110] In the present application, the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, device or device including the elements; if there is a description of "first", "second", etc., it is only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the order of the indicated technical features. In addition, in the description of the present application, unless otherwise specified, the terms "multiple" and "multiple" mean at least two.

[0111] Finally, it should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "an example" or "some examples" 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 application. In this specification, the schematic representation of the above terms does 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.

[0112] Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary, and the contents described are only embodiments adopted for the convenience of understanding the present application, and are not intended to limit the present application. Any technician in the technical field to which the present application belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present application, but the scope of protection of the present application shall still be based on the scope defined in the attached claims.

Claims

1. A method for measuring the amine concentration in a desulfurization amine solution by near infrared spectroscopy, characterized in that: The following steps are involved: S1: Use different concentrations of desulfurization amine solution samples and determine the amine concentration of the samples using the standard method. S2: measuring the near infrared spectra of the desulfurization amine solution samples of different concentrations in step S1, selecting characteristic spectral regions for second-order differential processing, and obtaining the absorbance of the desulfurization amine solution samples of different concentrations; S3: Correlate the absorbance of the desulfurization amine solution samples of different concentrations obtained in step S2 with the amine concentrations of the desulfurization amine solution samples of different concentrations obtained in step S1, perform regression analysis, and establish a calibration model for determining amine concentrations. S4: measuring the near infrared spectrum of the sample to be tested, selecting the characteristic spectrum for second-order differential processing, and obtaining the absorbance of the sample to be tested; S5: Substitute the absorbance of the sample to be tested in step S4 into the calibration model obtained in step S3 to obtain the amine concentration of the sample to be tested.

2. The method according to claim 1, characterized in that In step S1, the number of desulfurization amine solution samples of different concentrations is not less than 40, preferably not less than 50, more preferably, the number of samples is 50-600, and further preferably, 100-500.

3. The method according to claim 1 or 2, characterized in that: In the step S1, the mass fraction range of the amine concentration of the desulfurization amine solution sample is 10.00 to 50.00%, preferably 25.00 to 45.00%.

4. The method according to any one of claims 1 to 3, characterized in that: In the step S1, the standard method is titration or chromatography, preferably titration.

5. The method according to any one of claims 1 to 4, characterized in that: The measurement conditions for measuring the near infrared spectrum in step S2 and step S4 are the same, and the measurement conditions include sample temperature and / or ambient temperature; preferably, the sample temperature is 20-40°C.

6. The method according to any one of claims 1 to 5, characterized in that: In step S2 and step S4, the range of the selected characteristic spectrum is 4000-6000cm -1 .

7. The method according to any one of claims 1 to 6, characterized in that: In step S2 and step S4, the second-order differential processing of the characteristic spectrum also includes vector normalization and mean centering processing independently.

8. The method according to any one of claims 1 to 7, characterized in that: In step S3, the regression analysis includes regression analysis as partial least squares method, least squares method, principal component regression, inverse least squares method or robust partial least squares method; preferably partial least squares method.

9. A computer-readable storage medium, characterized in that: The computer program stored in the computer-readable storage medium can be executed by one or more processors to implement the method according to any one of claims 1 to 8.

10. An electronic device, characterized in that: The method comprises a memory and one or more processors, wherein a computer program is stored in the memory, and the memory and the one or more processors are communicatively connected with each other, and when the computer program is executed by the one or more processors, the method as described in any one of claims 1 to 8 is executed.

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