CN103868881A - Method for test of wax content in asphalt - Google Patents

Abstract

The invention discloses a method for test of wax content in asphalt, the method is as follows: testing a near infrared spectrum of a to-be-tested asphalt sample; performing second-order differential of the near infrared spectrum of the to-be-tested asphalt sample, and then performing normalization processing; by use of near infrared spectrums in a pre-established near infrared spectral database of multiple asphalt samples and the near infrared spectrum of the normalized to-be-tested asphalt sample, calculating a fitting spectrum of the to-be-tested asphalt sample, wherein each near infrared spectrum in the database of the multiple asphalt samples is corresponding to each asphalt wax content of each asphalt sample; calculating a fitting degree of the to-be-tested asphalt sample according to the near infrared spectrum and the fitting spectrum of the normalized to-be-tested asphalt sample; and comparing the fitting degree with a preset threshold value, in the case of the fitting degree being not less than the threshold value, calculating the wax content of the to-be-tested asphalt sample according to the asphalt wax content corresponding to the near infrared spectrum in the database of the asphalt samples involved in the calculating of the fitting spectrum. By use of the method, the wax content in asphalt can be rapidly and accurately tested.

Description

Measure the method for wax content in asphalt

Technical field

The present invention relates to a kind of method of measuring wax content in asphalt, particularly, relate to a kind of method of utilizing near infrared ray wax content in asphalt.

Background technology

Wax content is larger to the performance impact of pitch, and the pavement performance such as the extensibility of the wax in petroleum bitumen to pitch, adhesiveness, thermal stability has utmost point adverse influence, and therefore wax content is one of important technical indicator of bi tumenf orr oad.

SH/T0425 has recorded the standard method of measuring wax content in asphalt, the method is that the distillate oil after asphalt sample cracking distillation is dissolved in to ether alcohol mixed solvent, cooling wax of separating out at-20 DEG C is filtered, filter wax petroleum ether dissolution, steam again solvent dry, obtain wax content thereby weigh.But this method complicated and time consumption and contaminated environment.

Near-infrared spectrum technique has and can many character measure simultaneously and be applicable to the features such as online nondestructive analysis, has been applied to more and more the fields such as petrochemical industry, agricultural and pharmacy at present, especially aspect process analysis procedure analysis, is bringing into play positive irreplaceable effect.But these technology all need to adopt chemometrics method to set up calibration model, and the calibration model of building has the specific scope of application, needs constantly calibration model to be carried out to expanding and updating.Setting up the multivariate calibration methods that quantitative correction model is conventional is offset minimum binary method (PLS), artificial neural network (ANN) or support vector machine (SVM) etc., also needs, according to concrete application, spectrum is carried out to the operation such as preferably of pre-service and spectrum range.Because selected parameter is many, multivariate calibration methods is compared with the reason such as indigestibility and grasp, the foundation of model needs trained professional to complete conventionally, this becomes the bottleneck problem that this technology of restriction is extensively promoted the use of, and a lot of near-infrared analyzers are all because calibration model is safeguarded its due effect of can not bringing into play not in time.

Summary of the invention

The object of this invention is to provide a kind of method of measuring wax content in asphalt, to solve above-mentioned the problems of the prior art.

To achieve these goals, the invention provides a kind of method of measuring wax content in asphalt, the method comprises: the near infrared spectrum of measuring pitch sample to be measured; The near infrared spectrum of pitch sample to be measured is carried out to second-order differential, then carry out normalized; The near infrared spectrum of the near infrared spectrum in the near infrared spectrum data storehouse of multiple pitch samples that utilization is set up in advance and the pitch sample to be measured after normalization calculates the matching spectrum of pitch sample to be measured, and the near infrared spectrum separately of the multiple pitch samples in database is corresponding with pitch wax content separately; Calculate the degree of fitting of pitch sample to be measured according to the near infrared spectrum of the pitch sample to be measured after normalization and matching spectrum; And by degree of fitting and default threshold value comparison, in the situation that degree of fitting is not less than threshold value, calculate the wax content of pitch sample to be measured according to the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating that has participated in matching spectrum in database.

By the near infrared spectrum data storehouse of multiple pitch samples of setting up in advance and through second-order differential process and normalization after the near infrared spectrum of pitch sample to be measured obtain matching spectrum, carry out digital simulation degree according to the near infrared spectrum of the pitch sample to be measured after matching spectrum and normalization, by the comparison of this degree of fitting and threshold value, in the situation that degree of fitting is not less than threshold value, calculate the wax content of pitch sample to be measured according to the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating that has participated in matching spectrum in database.The method is without setting up calibration model, simple to operate, and user does not need to grasp more professional knowledge just can measure pitch wax content to be measured quickly and accurately.

Other features and advantages of the present invention are described in detail the embodiment part subsequently.

Brief description of the drawings

Accompanying drawing is to be used to provide a further understanding of the present invention, and forms a part for instructions, is used from explanation the present invention, but is not construed as limiting the invention with embodiment one below.In the accompanying drawings:

Fig. 1 is according to the process flow diagram of the method for the mensuration wax content in asphalt of the embodiment of the present invention; And

Fig. 2 is the pitch sample to be measured near infrared spectrum after measured and the schematic diagram that contrasts of matching spectrum according to the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is elaborated.Should be understood that, embodiment described herein only, for description and interpretation the present invention, is not limited to the present invention.

Fig. 1 is according to the process flow diagram of the method for the mensuration wax content in asphalt of the embodiment of the present invention.

As shown in Figure 1, the method comprises:

S100, measures the near infrared spectrum of pitch sample to be measured;

S102, carries out second-order differential to the near infrared spectrum of pitch sample to be measured, then carries out normalized;

S104, the near infrared spectrum of the near infrared spectrum in the near infrared spectrum data storehouse of multiple pitch samples that utilization is set up in advance and the pitch sample to be measured after normalization calculates the matching spectrum of pitch sample to be measured, and the near infrared spectrum separately of the multiple pitch samples in database is corresponding with pitch wax content separately;

S106, calculates the degree of fitting of pitch sample to be measured according to the near infrared spectrum of the pitch sample to be measured after normalization and matching spectrum; And

S108, by degree of fitting and default threshold value comparison, in the situation that degree of fitting is not less than threshold value, calculates the wax content of pitch sample to be measured according to the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating that has participated in matching spectrum in database.

By the near infrared spectrum data storehouse of multiple pitch samples of setting up in advance and through second-order differential process and normalization after the near infrared spectrum of pitch sample to be measured obtain matching spectrum, carry out digital simulation degree according to the near infrared spectrum of the pitch sample to be measured after matching spectrum and normalization, by the comparison of this degree of fitting and threshold value, in the situation that degree of fitting is not less than threshold value, calculate the wax content of pitch sample to be measured according to the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating that has participated in matching spectrum in database.The method is without setting up calibration model, simple to operate, and user does not need to grasp more professional knowledge just can measure pitch wax content to be measured quickly and accurately.

In the present embodiment, step S104 comprises:

S1042, according to the near infrared spectrum near infrared spectrum and the database of the pitch sample to be measured after normalization, the fitting coefficient of the near infrared spectrum in computational data storehouse;

S1044, is normalized and obtains normalization fitting coefficient the non-zero fitting coefficient in fitting coefficient;

S1046, according to the near infrared spectrum digital simulation spectrum in normalization fitting coefficient and database.

In step S1042, utilize nonnegativity restrictions least square method according to the near infrared spectrum digital simulation coefficient near infrared spectrum and the database of the pitch sample to be measured after normalization.For example,, according to following formula digital simulation coefficient:

$x=\underset{i=1}{\overset{k}{\mathrm{\Σ}}}{a}_i{v}_i---\left(1\right),$

And meet following objective function:

$\min \left|\right|x-\underset{i=1}{\overset{k}{\mathrm{\Σ}}}{a}_i{v}_i\left|\right|,$ Constraint condition (s.t.): a _i>=0,

X is the near infrared spectrum of the pitch sample to be measured after normalization, v _ifor i near infrared spectrum in database, k is the quantity of the near infrared spectrum in database, a _ifor i the fitting coefficient that near infrared spectrum is corresponding in database.

the near infrared spectrum that represents the pitch sample to be measured after normalization with

the minimum value of the absolute value of the difference between (near infrared spectrum of the pitch sample to be measured calculating).

In step S1044, according to following formula, the non-zero fitting coefficient in fitting coefficient is normalized and obtains normalization fitting coefficient:

$b_i=\frac{{a^{\′}}_i}{\underset{i=1}{\overset{g}{\mathrm{\Σ}}}{a^{\′}}_i}---\left(2\right),$

Wherein b _ifor normalization fitting coefficient, a ' _ifor having the non-zero fitting coefficient of i near infrared spectrum in the near infrared spectrum of non-zero fitting coefficient in database, g is the quantity in database with the near infrared spectrum of non-zero fitting coefficient.

In step S1046, according to following formula digital simulation spectrum:

$\hat{x}=\underset{i=1}{\overset{g}{\mathrm{\Σ}}}{b}_i{v}_i---\left(3\right),$

Wherein

for matching spectrum, v _ifor the individual near infrared spectrum with non-zero fitting coefficient of the i in database.

In step S106, according to following formula digital simulation degree:

$s=0.001/\sqrt{\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{({\hat{x}}_j-x_j)}^2/(m-1)}---\left(4\right),$

Wherein s is degree of fitting, x _jfor the absorbance of j the wavelength points of near infrared spectrum of the pitch sample to be measured after normalization, for the absorbance of j wavelength points of matching spectrum, m is that wavelength is counted.

In the present embodiment, step S108 comprises:

S1082, by degree of fitting and default threshold value comparison, if degree of fitting is not less than threshold value, goes to step S1084, otherwise finishes;

S1084, calculates the wax content of pitch sample to be measured according to the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating that has participated in matching spectrum in database.Wherein calculate the wax content of pitch sample to be measured according to following formula:

$\hat{y}=\underset{i=1}{\overset{g}{\mathrm{\Σ}}}{b}_i{q}_i---\left(5\right),$

Wherein

for the wax content of the pitch sample to be measured that calculates, q _ifor having participated in the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating of matching spectrum in database.

In the present embodiment, by the spectral range of near infrared spectrum of pitch sample to be measured of carrying out second-order differential at 4000～7000cm ^-1between.

In the present embodiment, can set up in advance by following step the database of the near infrared spectrum that comprises multiple pitch samples:

Collect multiple representative pitch samples;

Measure the near infrared spectrum of each sample, and use standard method (for example, SH/T0425 of the prior art) to measure the wax content of each sample;

The near infrared spectrum of each sample is carried out to second-order differential, then carry out normalized;

Near infrared spectrum by each sample after normalized and its wax content corresponding database of setting up the near infrared spectrum that comprises multiple pitch samples one by one of measuring with standard method.

Wherein, the quantity of multiple representative pitch samples can be 150.The spectral range of the near infrared spectrum of each representative pitch sample can be at 4000～7000cm ^-1between.

In the present embodiment, can determine predetermined threshold value according to following step:

Choose a crude oil sample, the near infrared spectrum of three these crude oil sample of replication;

According to formula: $\mathrm{sr}=0.001/\sqrt{\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{\left({x^{\′}}_j\right)}^2/(m-1)}---\left(6\right)$

Calculate pseudo-degree of fitting (sr) value, get maximum sr value and be multiplied by coefficient 0.75 and be threshold value.Wherein x ' _jfor the absorbance of j the wavelength points of near infrared spectrum of crude oil sample, m is that wavelength is counted.The spectral range of the near infrared spectrum of this crude oil sample can be at 4000～7000cm ^-1between.

Illustrate according to the method for the mensuration wax content in asphalt of the embodiment of the present invention, particularly in the mode of example below:

Collecting 150 representative pitch samples uses said method to set up the database of the near infrared spectrum that comprises multiple pitch samples.

Choose a crude oil sample, measure the near infrared spectrum of three these crude oil sample, calculate pseudo-degree of fitting (sr) value according to formula (6), get maximum sr value and be multiplied by coefficient 0.75 and be threshold value s _v.In this example, s _vcan be for example 2.35.

Choose 10 pitch samples to be measured, according to step S100 to S104 digital simulation spectrum, the quantity wherein in database with the near infrared spectrum of non-zero fitting coefficient is 9, sees table 1.

Table 1

Sequence number	Near infrared spectrum numbering in database	Fitting coefficient
			1	0019	0.3304
2	0022	0.1208
			3	0062	0.0096
4	0067	0.1046
			5	0075	0.1336
6	0102	0.2086
			7	0110	0.0281
8	0103	0.0622
			9	0150	0.0018

Fig. 2 is the pitch sample to be measured near infrared spectrum after measured and the schematic diagram that contrasts of matching spectrum according to the embodiment of the present invention.As shown in Figure 2, near infrared spectrum after measured almost overlaps completely with the matching spectrum calculating.Hence one can see that, can be by the near infrared spectrum of matching pitch sample to be measured well of 9 near infrared spectrums in above-mentioned database.Wherein, calculate the degree of fitting of above-mentioned 10 pitch samples to be measured according to formula (4), the degree of fitting of these 10 pitch samples to be measured is as shown in table 2.

Table 2

Sequence number	Degree of fitting
		1	5.51
2	12.31
		3	11.13
4	6.45
		5	7.37
6	8.73
		7	7.54
8	6.47
		9	10.08
10	8.90

Known according to table 2, the degree of fitting of these 10 pitch samples to be measured is all greater than threshold value s _v, pitch sample to be measured has obtained good matching.Then can calculate according to formula (5) wax content of pitch sample to be measured.The comparing result of the wax content data that the method for the mensuration wax content in asphalt of 10 pitch sample evidence embodiment of the present invention to be measured is measured and the measured data of SH/T0425 method is in table 3.

Table 3

Sequence number	Predicted value, quality %	Measured value, quality %	Deviation, quality %
				1	2.06	2.04	0.02
2	2.40	2.40	0
				3	2.79	3.02	-0.23
4	1.93	2.02	-0.09
				5	1.49	1.46	0.03
6	1.03	1.30	-0.27
				7	1.25	1.38	-0.13
8	0.67	0.63	0.04
				9	2.03	1.93	0.1
10	2.36	2.40	-0.04

Data are as shown in Table 3 known, can Accurate Determining pitch wax content according to the method for the mensuration wax content in asphalt of the embodiment of the present invention.

Can find out from above-described embodiment, by the near infrared spectrum data storehouse of multiple pitch samples of setting up in advance and through second-order differential process and normalization after the near infrared spectrum of pitch sample to be measured obtain matching spectrum, by the near infrared spectrum digital simulation degree of the pitch sample to be measured after matching spectrum and normalization, by the comparison of this degree of fitting and threshold value, in the situation that degree of fitting is not less than threshold value, calculate the wax content of pitch sample to be measured according to the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating that has participated in matching spectrum in database.The method is without setting up calibration model, simple to operate, and user does not need to grasp more professional knowledge just can measure pitch wax content to be measured quickly and accurately.

Below describe by reference to the accompanying drawings the preferred embodiment of the present invention in detail; but; the present invention is not limited to the detail in above-mentioned embodiment; within the scope of technical conceive of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.

It should be noted that in addition each the concrete technical characterictic described in above-mentioned embodiment, in reconcilable situation, can combine by any suitable mode.For fear of unnecessary repetition, the present invention is to the explanation no longer separately of various possible array modes.

In addition, also can carry out combination in any between various embodiment of the present invention, as long as it is without prejudice to thought of the present invention, it should be considered as content disclosed in this invention equally.

Claims (8)

1. a method of measuring wax content in asphalt, the method comprises:

Measure the near infrared spectrum of pitch sample to be measured;

The near infrared spectrum of described pitch sample to be measured is carried out to second-order differential, then carry out normalized;

The near infrared spectrum of the near infrared spectrum in the near infrared spectrum data storehouse of multiple pitch samples that utilization is set up in advance and the pitch sample to be measured after normalization, calculate the matching spectrum of described pitch sample to be measured, the near infrared spectrum separately of the multiple pitch samples in described database is corresponding with pitch wax content separately;

According to the near infrared spectrum of the pitch sample to be measured after described normalization and described matching spectrum, calculate the degree of fitting of described pitch sample to be measured; And

By described degree of fitting and default threshold value comparison, in the situation that described degree of fitting is not less than described threshold value, calculate the wax content of described pitch sample to be measured according to the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating that has participated in described matching spectrum in described database.

2. method according to claim 1, wherein, the matching spectrum that calculates described pitch sample to be measured comprises:

According to the near infrared spectrum in the near infrared spectrum of the pitch sample to be measured after described normalization and described database, calculate the fitting coefficient of the near infrared spectrum in described database;

Non-zero fitting coefficient in described fitting coefficient is normalized and obtains normalization fitting coefficient;

According to the near infrared spectrum in described normalization fitting coefficient and described database, calculate described matching spectrum.

3. method according to claim 2, wherein, utilizes nonnegativity restrictions least square method to calculate described fitting coefficient according to the near infrared spectrum in the near infrared spectrum of the pitch sample to be measured after described normalization and described database.

4. according to the method described in any one claim in claim 2-3, wherein, according to following formula, the non-zero fitting coefficient in described fitting coefficient is normalized and obtains normalization fitting coefficient:

$b_i=\frac{{a^{\′}}_i}{\underset{i=1}{\overset{g}{\mathrm{\Σ}}}{a^{\′}}_i},$

Wherein b _ifor normalization fitting coefficient, a ' _ifor having the non-zero fitting coefficient of i near infrared spectrum in the near infrared spectrum of non-zero fitting coefficient in described database, g is the quantity in described database with the near infrared spectrum of non-zero fitting coefficient.

5. method according to claim 4, wherein, calculate described matching spectrum according to following formula:

$\hat{x}=\underset{i=1}{\overset{g}{\mathrm{\Σ}}}{b}_i{v}_i,$

Wherein

for described matching spectrum, v _ifor the individual near infrared spectrum with non-zero fitting coefficient of the i in described database.

6. according to the method described in any one claim in claim 1-3, wherein, calculate described degree of fitting according to following formula:

$s=0.001/\sqrt{\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{({\hat{x}}_j-x_j)}^2/(m-1)},$

Wherein s is described degree of fitting, x _jfor the absorbance of j the wavelength points of near infrared spectrum of the pitch sample to be measured after described normalization,

for the absorbance of j wavelength points of described matching spectrum, m is that wavelength is counted.

7. method according to claim 4, wherein, calculate the wax content of described pitch sample to be measured according to following formula:

$\hat{y}=\underset{i=1}{\overset{g}{\mathrm{\Σ}}}{b}_i{q}_i,$

Wherein

for the wax content of the pitch sample described to be measured that calculates, q _ifor having participated in the corresponding pitch wax content of near infrared spectrum of pitch sample of calculating of described matching spectrum in described database.

8. according to the method described in any one claim in claim 1-3, wherein, by the spectral range of near infrared spectrum of pitch sample described to be measured of carrying out second-order differential at 4000～7000cm ^-1between.

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