CN103091265A - Analysis method for ingredients and mixing ratio of oil product and mixed oil by using terahertz spectroscopy - Google Patents

Abstract

The invention discloses an analysis method for ingredients and a mixing ratio of an oil product and mixed oil by using terahertz spectroscopy. The method comprises the following steps of: acquiring a terahertz frequency range, and solving a signal sn ( sequential number) (t) of nsi (nitrogen solubility index) (1THz) measured by a plurality of times which is changed along a measurement time; determining a time period t1- t2 of the mixed oil in the measurement time according to the signal sn (t); respectively solving oil product types in pipeline sequence transportation in the 0-t1 time and t2-tend time; carrying out least square fitting on an absorption coefficient alpha si (w) which corresponds to a measuring sequence appeared in the t1-t2 time in the terahertz frequency range, and solving respective volume percentages of two types of the oil products in the corresponding mixed oil. The two mixed oil products decided by the invention are stable and accurate in results and low in misjudgment rate. The mixing ratio obtained by the least square fitting and an actual mixing ratio have an average error which is 4.3%, and oil mixed regions in the oil product pipeline sequence transportation can be precisely cut and divided.

Description

Tera-hertz spectra is to the composition of product oil and contaminated product and the analytical approach of blending ratio

Technical field

The present invention relates to the analysis to product oil and contaminated product, particularly a kind of tera-hertz spectra is to the composition of product oil and contaminated product and the analytical approach of blending ratio.

Background technology

Product oil adopts the mode of batch transportation in pipeline is carried, namely in a pipeline, by certain batch and different types of oil product of order delivery.Due to the impact of the factors such as change in flow, viscosity differences, density and change caliber, in pipeline, the oil product of two kinds of adjacent conveyor can mix, and forms contaminated product.The two kind oil of the contaminated product that forms before physics and chemistry is different from mixing in nature, thereby can not use as qualified product oil.Contaminated product has not only caused the loss of product oil, produces economic loss, and has reduced the quality of oil product, causes security incident easily for industry and life.Therefore, must seek and a kind ofly can analyze and identify the kind of two kinds of oil products in miscella and the method for blending ratio, thereby the contaminated product district in pipeline in batch transportation is cut accurately and divides.

Traditional optical detection way is to utilize infrared spectrum technology to measure oil product at the absorption spectrum of near infrared, mid-infrared light spectral limit, and its detection time is long can't satisfy the online demand that detects of petroleum pipe line.Compare with infrared spectrum technology, the terahertz light spectral technology has superiority: at first, the typical pulse-widths of tera-hertz spectra is at picosecond magnitude, and temporal resolution is high; Secondly, the vibration of organic molecule, rotational energy level all are in terahertz wave band, therefore utilize tera-hertz spectra can obtain the more abundant chemical information of tested oil product, realize the feature identification of oil product; Again, Terahertz photon energy low (1THZ place be 4meV) can cause danger when THz wave is passed inflammable oil product; At last, tera-hertz spectra has very high time and spatial coherence, and signal to noise ratio (S/N ratio) is greater than 10 ⁴: 1.Do Fourier transform by the time domain waveform that Terahertz is detected gained and just can obtain frequency domain spectrum, and then obtain amplitude and the phase spectrum data of oil product, solve the optical signature parameters such as refractive index, absorption coefficient of tested oil product.According to the optical signature parameter of obtaining, tested oil product is analyzed and identified.

The inventor finds to exist at least in prior art following shortcoming and defect in realizing process of the present invention:

Existing terahertz time-domain spectroscopy analysis to product oil and miscella thereof is all in the situation that the kind of known oil product is carried out, can't complete ONLINE RECOGNITION and analysis to two kinds of unknown oil product miscellas of batch transportation in pipeline, the accurate information of contaminated product in pipeline can not be provided for the receiving station of pipeline batch transportation, this will reduce the quality of product oil, cause a large amount of wastes of product oil, bring certain economic loss.

Summary of the invention

The invention provides a kind of tera-hertz spectra to the composition of product oil and contaminated product and the analytical approach of blending ratio, realized the ONLINE RECOGNITION to two kinds of unknown oil product miscellas of batch transportation, improved the quality of product oil, reduced the loss of product oil in the pipeline batch transportation, this scheme is specially:

A kind of tera-hertz spectra said method comprising the steps of the composition of product oil and contaminated product and the analytical approach of blending ratio:

(1) obtain the Terahertz frequency range, and solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t);

(2) according to described signal s _n(t) determine the time period t that contaminated product occurs in Measuring Time ₁~ t ₂Ask at 0 ~ t respectively ₁In time and t ₂~ t _endProduct oil kind in time interior conduit batch transportation;

(3) in described Terahertz frequency range, to t ₁~ t ₂Absorption coefficient corresponding to measurement order that occurs in time _si(w) carry out least square fitting, find the solution in corresponding contaminated product two kinds of product oils percent by volume separately.

Describedly obtain the Terahertz frequency range, and solve the n that repeatedly measures _siThe signal that (1THz) changes with Measuring Time is specially:

1) obtain respectively by the terahertz time-domain waveform S (t) that fills the sample cuvette and the reference terahertz time-domain waveform R (t) that passes through the empty cuvette of same thickness, to pretreated time-domain signal s ' (t) and R ' (t) do Fourier transform, obtain the Fourier transform of sample signal

Fourier transform with reference signal

And both ratios are expressed as amplitude ρ (w) and phase place

The form of product;

2) by described amplitude ρ (w) and described phase place

Find the solution refractive index and the absorption coefficient of sample;

3) obtain the refractive index n of oil product when measuring for the i time _si(w) and absorption coefficient _siAnd extract the refractive index of oil product when measuring for the i time at the value n at 1THz frequency place (w), _si(1THz);

4) find the solution described absorption coefficient _si(w) coefficient of distinguish A _α, intercept out A _αChanging value is no more than the described Terahertz frequency range of preset value;

5) in described Terahertz frequency range, solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t).

Described pre-service is specially: intercept out the time-domain signal part before reflection peak arrives, and in the described time-domain signal part back zero padding that intercepts, obtain pretreated described time-domain signal s'(t) and R ' is (t).

Described in described Terahertz frequency range, solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t) be specially:

Utilize the measuring intervals of TIME of measuring order and terahertz time-domain spectroscopy instrument to solve Measuring Time, as transverse axis, take the refractive index amplitude as the longitudinal axis, set up cartesian coordinate system; Solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t).

Described according to described signal s _n(t) determine the time period t that contaminated product occurs in Measuring Time ₁~ t ₂Ask at 0 ~ t respectively ₁In time and t ₂~ t _endProduct oil kind in time interior conduit batch transportation is specially:

1) with described signal s _n(t) amplitude for the first time and last the initial time t that the initial time that changes greater than preset value arrives as contaminated product district in the pipeline batch transportation respectively occurs ₁With contaminated product end of extent moment t ₂

2) will be at 0 ~ t ₁Refractive index corresponding to measurement order that occurs in time is averaged, and obtains

Will be at t ₂~ t _endRefractive index corresponding to measurement order that occurs in time is averaged, and obtains

3) in described Terahertz frequency range, find the solution

With the residual values of four kinds of product oil refractive indexes, product oil corresponding to Minimum Residual difference is 0 ~ t ₁Product oil kind in time interior conduit batch transportation in like manner, is determined at t ₂~ t _endProduct oil kind in time interior conduit batch transportation.

Described to t ₁~ t ₂Absorption coefficient corresponding to measurement order that occurs in time _si(w) carry out least square fitting, find the solution in corresponding contaminated product two kinds of product oils separately percent by volume be specially:

α _si(w)=c _iα ₁(w)+d _iα ₂(w)，i＝1,2,3，...,n

N measures number of times, α for all that complete in the contaminated product district ₁(w) and α ₂(w) be respectively the absorption coefficient of two kinds of product oils that decision-making goes out, c _iAnd d _iBe respectively the percent by volume of the first product oil and the second product oil in the contaminated product of measuring for the i time.

The beneficial effect of technical scheme provided by the invention is: at first decision-making goes out two kinds of product oils that mix in contaminated product district's generation to this method according to refractive index; According to Beer-Lambert law, by least square fitting, solve two kinds of product oils volume ratio separately again.Through theoretical analysis and experimental verification, the result of go out by this method decision-making two kinds kinds of mixing oil products is stable accurately, False Rate is low, the blending ratio that goes out by least square fitting and actual mixture ratio example error average out to 4.3% can cut accurately and divide contaminated product district in the products pipeline sequential delivery.

Description of drawings

Fig. 1 is tera-hertz spectra provided by the invention to the process flow diagram of the analytical approach of the composition of product oil and contaminated product and blending ratio;

Fig. 2 is tera-hertz spectra provided by the invention to another process flow diagram of the analytical approach of the composition of product oil and contaminated product and blending ratio;

Fig. 3 is the online contaminated product district's identification based on terahertz time-domain spectroscopic technology provided by the invention and the system schematic of analyzing;

Fig. 4 is the reference waveform R (t) of product oil terahertz time-domain waveform s provided by the invention (t) and empty sample cell;

Fig. 5 is product oil refractive index n provided by the invention _s90(w), n _s93(w), n _s97(w) and n _{S-10 diesel oil}(w) curve;

Fig. 6 is the curve map of the coefficient of distinguish A α of 97# gasoline provided by the invention and 11 kinds of blending ratio contaminated products of-10 diesel oil;

Fig. 7 is provided by the invention according to A _αIntercept out the absorption coefficient curve distribution figure of 97# gasoline and 11 kinds of blending ratio contaminated products of-10 diesel oil in the frequency range of studying;

Fig. 8 is the 97# gasoline volume ratio curve that solves of least square fitting provided by the invention and the distribution plan of theoretical curve.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, embodiment of the present invention is described further in detail below in conjunction with accompanying drawing.

In order to realize the ONLINE RECOGNITION to two kinds of unknown oil product miscellas of batch transportation, improve the quality of product oil, reduce the loss of product oil in the pipeline batch transportation, referring to Fig. 1, the embodiment of the present invention provides a kind of tera-hertz spectra to the composition of product oil and contaminated product and the analytical approach of blending ratio, sees for details hereinafter to describe:

Embodiment 1

101: obtain the Terahertz frequency range, and solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t);

102: according to signal s _n(t) determine the time period t that contaminated product occurs in Measuring Time ₁~ t ₂Ask at 0 ~ t respectively ₁In time and t ₂~ t _endProduct oil kind in time interior conduit batch transportation;

103: in the Terahertz frequency range, to t ₁~ t ₂Absorption coefficient corresponding to measurement order that occurs in time _si(w) carry out least square fitting, find the solution in corresponding contaminated product two kinds of product oils percent by volume separately.

Further, step 101 is specially:

1) obtain respectively by the terahertz time-domain waveform S (t) that fills the sample cuvette and the reference terahertz time-domain waveform R (t) that passes through the empty cuvette of same thickness, again to pretreated signal s'(t) and R ' (t) do Fourier transform, obtain the Fourier transform of sample signal

Fourier transform with reference signal And both ratios are expressed as amplitude ρ (w) and phase place

The form of product;

2) by amplitude ρ (w) and phase place Find the solution refractive index and the absorption coefficient of sample;

3) obtain the refractive index n of oil product when measuring for the i time _si(w) and absorption coefficient _siAnd extract the refractive index of oil product when measuring for the i time at the value n at 1THz frequency place (w), _si(1THz);

4) find the solution absorption coefficient _si(w) coefficient of distinguish A _α, intercept out A _αChanging value is no more than the described Terahertz frequency range of preset value;

5) in the Terahertz frequency range, solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t).

Further, pre-service is specially: the time-domain signal part before intercepting out reflection peak and arriving, and in the described time-domain signal part back zero padding of intercepting, obtain pretreated described time-domain signal s ' (t) and R ' (t).

Further, in the Terahertz frequency range, solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t) be specially:

Utilize the measuring intervals of TIME of measuring order and terahertz time-domain spectroscopy instrument to solve Measuring Time, as transverse axis, take the refractive index amplitude as the longitudinal axis, set up cartesian coordinate system; Solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t).

Further, according to signal s _n(t) determine the time period t that contaminated product occurs in Measuring Time ₁~ t ₂Ask at 0 ~ t respectively ₁In time and t ₂~ t _endProduct oil kind in time interior conduit batch transportation is specially:

1) with signal s _n(t) amplitude for the first time and last the initial time t that the initial time that changes greater than preset value arrives as contaminated product district in the pipeline batch transportation respectively occurs ₁With contaminated product end of extent moment t ₂

2) will be at 0 ~ t ₁Refractive index corresponding to measurement order that occurs in time is averaged, and obtains

Will be at t ₂~ t _endRefractive index corresponding to measurement order that occurs in time is averaged, and obtains

3) in the Terahertz frequency range, find the solution

With the residual values of four kinds of product oil refractive indexes, product oil corresponding to Minimum Residual difference is 0 ~ t ₁Product oil kind in time interior conduit batch transportation in like manner, is determined at t ₂~ t _endProduct oil kind in time interior conduit batch transportation.

Further, to t ₁~ t ₂Absorption coefficient corresponding to measurement order that occurs in time _si(w) carry out least square fitting, find the solution in corresponding contaminated product two kinds of product oils separately percent by volume be specially:

α _si(w)=c _iα ₁(w)+d _iα ₂(w)，i＝1,2,3，...,n

N measures number of times, α for all that complete in the contaminated product district ₁(w) and α ₂(w) be respectively the absorption coefficient of two kinds of product oils that decision-making goes out, c _iAnd d _iBe respectively the percent by volume of the first product oil and the second product oil in the contaminated product of measuring for the i time.

Realized the composition of product oil and contaminated product and the analysis of blending ratio by above-mentioned steps 101-step 103, determined composition in the contaminated product and the ratio of every kind of oil.

Embodiment 2

The below describes tera-hertz spectra in detail to the composition of product oil and contaminated product and the analytical approach of blending ratio with four kinds of product oils (90#, 93#, 97# and-10 diesel oil) of batch transportation laboratory sample as miscella, referring to Fig. 2, sees for details hereinafter and describes:

201: get in pipeline four kinds of oil products of batch transportation appropriate, as laboratory sample, obtain respectively by the terahertz time-domain waveform S (t) that fills the sample cuvette, the reference terahertz time-domain waveform R (t) that passes through the empty cuvette of same thickness according to the terahertz time-domain spectroscopy instrument;

Referring to Fig. 3 and Fig. 4, record respectively the reference terahertz time-domain waveform R (t) of the empty cuvette of the terahertz time-domain waveform S (t) of the cuvette that appropriate four kinds of product oils (90#, 93#, 97# gasoline and-10 diesel oil) sample is housed and same thickness by the terahertz time-domain spectroscopy instrument.The quantity of product oil and type are set according to the needs in practical application, and the embodiment of the present invention does not limit this.

Wherein, the present embodiment cuvette used is the infrared quartz cuvette, and light path thickness is 10mm.The material of cuvette and light path thickness can be chosen according to the practical application needs, and the embodiment of the present invention does not limit this.

202: carry out pre-service to terahertz time-domain waveform S (t) with reference to terahertz time-domain waveform R (t), obtain pretreated time-domain signal s'(t) and R'(t);

This step is specially: intercept out the time-domain signal part before reflection peak arrives, and the time-domain signal part back zero padding that is intercepting, obtain pretreated time-domain signal s ' (t) and R ' (t), reflection peak is produced by the reflection of the quartz of infrared quartz cuvette.For example: in the terahertz time-domain waveform, intercepting is come from the measurement zero-time and is risen to quartzy little reflection peak arrival time domain waveform before, and then in time domain waveform end zero padding, it is 2048 points that the time domain waveform that intercepts out in the present embodiment is counted, zero padding to 8192 point.Can select different time domain waveforms to count according to practical application yet and count with zero padding, the embodiment of the present invention limit this.

203: to time-domain signal s'(t) and R'(t) do respectively Fourier transform, obtain the Fourier transform of sample signal Fourier transform with reference signal

Ratio both is expressed as amplitude ρ (w) and phase place

The form of product;

Be about to

Be expressed as amplitude ρ (w) and phase place The form of product is specially:

$\tilde{E}s\left(w\right)/{\tilde{E}}_r\left(w\right)=\mathrm{\ρ}\left(w\right)\·e^{-j.\mathrm{\φ}\left(w\right)}---\left(1\right)$

Amplitude ρ (w) and phase place

Expression formula be respectively:

$\mathrm{\&rho;}\left(w\right)=n_s\&CenterDot;{\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00002876662800031.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+1}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00002876662800031.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+n_s}\right)}^2\&CenterDot;e^{-\frac{k_s{w}_d}{c}}---\left(2\right)$

In formula (2) and (3), n _sBe the real refractive index of sample, n ₁Be the refractive index of the quartz of making cuvette, k _sBe the extinction coefficient of sample, w is angular frequency, and d is the thickness of the sample that in cuvette, THz wave is passed, and c is the light velocity in vacuum.

204: derive according to fresnel's law the solution formula that single Thickness Method is asked refractive index and absorption coefficient, utilize amplitude ρ (w) and phase place

Solve the refractive index n of sample _sA(w), n _sB(w), n _sC(w) and n _sD(w) and absorption coefficient _sA(w), α _sB(w), α _sC(w) and α _sD(w);

Referring to Fig. 5, refractive index n _s(w) and absorption coefficient _s(w) be respectively:

${\mathrm{\&alpha;}}_s\left(w\right)=\frac{2}{d}\ln \left[\frac{\mathrm{\&rho;}\left(w\right)\&CenterDot;{({\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00002876662800031.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+n_s\left(w\right))}^2}{n_s\left(w\right)\&CenterDot;{({\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00002876662800031.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+1)}^2}\right]---\left(5\right)$

205: on-the-spot in the pipeline batch transportation, with the terahertz time-domain spectroscopy instrument, the oil product of the conveying in pipeline is repeatedly measured online the refractive index n of the oil product when obtaining the i time measurement _si(w) and absorption coefficient _siAnd extract the refractive index of oil product when measuring for the i time at the value n at 1THz frequency place (w), _si(1THz);

206: find the solution absorption coefficient _si(w) coefficient of distinguish A _α, intercept out A _αChanging value is no more than the Terahertz frequency range of preset value;

$A_{\mathrm{\&alpha;}}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{{[p_i\left({\mathrm{\&omega;}}_j\right)-{\stackrel{\&OverBar;}{p}}_j]}^2}{n},$ j=0,1,2,3...N-1 （6）

$p_i=\frac{d{{\mathrm{\&alpha;}}^{\&prime;}}_{\mathrm{si}}\left(w\right)}{\mathrm{dw}},$ i=1,2,3...n （7）

${\stackrel{\&OverBar;}{p}}_j=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{p}_i\left({\mathrm{\&omega;}}_j\right)}{n},j=\mathrm{0,1,2,3}...N-1---\left(8\right)$

I represents to measure for the i time, and the measurement number of times of n for completing in the contaminated product district, j are the number of data points of the absorption coefficient that intercepts out, and N is all number of data points of the absorption coefficient that intercepts out, p _iBe the absorption coefficient measured for the i time to the first order derivative of w,

For the first order derivative curve of n bar absorption coefficient at w _jThe mean value of individual data point.

Can be clearly seen that coefficient of distinguish A referring to Fig. 6 _αValue and variation tendency, A _αBe worth littlely, curve more meets linear relationship, according to Beer-Lambert law, the absorption coefficient of liquid in theory with the linear relation of its concentration, intercept out and have optimum linear (A _αChanging value is no more than preset value) frequency part as the frequency range of research, the frequency range that the present embodiment intercepts out is 0.25-1.5THZ, the result that intercepts out as shown in Figure 7, frequency range is chosen according to the needs in practical application, the embodiment of the present invention does not limit this.

207: in the Terahertz frequency range, utilize the measuring intervals of TIME of measuring order and terahertz time-domain spectroscopy instrument to solve Measuring Time, as transverse axis, take the refractive index amplitude as the longitudinal axis, set up cartesian coordinate system, solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t);

Wherein, utilizing the measuring intervals of TIME of measuring order and terahertz time-domain spectroscopy instrument to solve Measuring Time is specially: it is 10 seconds that the present embodiment terahertz light spectrometer used is completed the one-shot measurement required time, the interval enters after 1 second next time and measures, to measure initial time as 0 moment, can solve Measuring Time.

208: with signal s _n(t) amplitude for the first time and last the initial time t that the initial time that changes greater than preset value arrives as contaminated product district in the pipeline batch transportation respectively occurs ₁With contaminated product end of extent moment t ₂, determine the time period t that contaminated product occurs in Measuring Time ₁~ t ₂

The time period that two kinds of oil that namely do not occur to mix occur in Measuring Time is 0 ~ t ₁And t ₂~ t _endPreset value is set according to the needs in practical application, describes take 0.0005 as example in the present embodiment.

209: will be at 0 ~ t ₁Refractive index corresponding to measurement order that occurs in time is averaged, and obtains

Will be at t ₂～t _endRefractive index corresponding to measurement order that occurs in time is averaged, and obtains

210: in the frequency range of intercepting, find the solution

With the residual values of four kinds of product oil refractive indexes, product oil corresponding to Minimum Residual difference is 0 ~ t ₁Product oil kind in time interior conduit batch transportation in like manner, is determined at t ₂~ t _endProduct oil kind in time interior conduit batch transportation;

Find the solution

Residual values with four kinds of product oils (90#, 93#, 97# and-10 diesel oil) refractive index is specially:

${\mathrm{\&sigma;}}_1=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\stackrel{\&OverBar;}{n}}_{{0-t}_1}\left(w_i\right)-n_{\mathrm{sA}}\left(w_i\right)]}^2---\left(9\right)$

${\mathrm{\&sigma;}}_2=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\stackrel{\&OverBar;}{n}}_{{0-t}_1}\left(w_i\right)-n_{\mathrm{sB}}\left(w_i\right)]}^2---\left(10\right)$

${\mathrm{\&sigma;}}_3=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\stackrel{\&OverBar;}{n}}_{{0-t}_1}\left(w_i\right)-n_{\mathrm{sC}}\left(w_i\right)]}^2---\left(11\right)$

${\mathrm{\&sigma;}}_4=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\stackrel{\&OverBar;}{n}}_{{0-t}_1}\left(w_i\right)-n_{\mathrm{sD}}\left(w_i\right)]}^2---\left(12\right)$

211: in the frequency range of intercepting, in conjunction with the absorption coefficient of two kinds of product oils, according to Beer-Lambert law, to t ₁~ t ₂Absorption coefficient corresponding to measurement order that occurs in time _si(w) carry out least square fitting, solve two kinds of product oil percent by volume c separately in corresponding contaminated product _iWith d _i

According to Beer-Lambert law, absorption coefficient and the concentration of non-scattering, non-polar liquid are linear, namely

α _si(w)=c _iα ₁(w)+d _iα ₂(w)，i=1,2,3，...,n （13）

In formula (13), α _si(w) be the absorption coefficient of measuring for the i time, n measures number of times, α for all that complete in the contaminated product district ₁(w) and α ₂(w) be respectively the absorption coefficient of two kinds of product oils that gone out by step 210 decision-making, c _iBe the percent by volume of the first product oil in the contaminated product of measuring at the i time, d _iIt is the percent by volume of the second product oil in the contaminated product of measuring for the i time.

The below verifies that with concrete experiment a kind of tera-hertz spectra that the embodiment of the present invention provides to the feasibility of the analytical approach of the composition of product oil and contaminated product and blending ratio, sees for details hereinafter and describes:

With four kinds of product oils (90#, 93#, 97# gasoline and-10 diesel oil) as laboratory sample, according to the refractive index of oil product in the pipeline that records in the pipeline batch transportation value at 1THz frequency place at every turn, mark off the time that contaminated product district in pipeline and single oil area occur on the Measuring Time section, in conjunction with the refractive index of oil product in four kinds of product oils (90#, 93#, 97# gasoline and-10 diesel oil) refractive index and the on-the-spot pipeline of batch transportation, determine two kinds of product oils that mix in contaminated product district's generation again; The oil product absorption coefficient in the on-the-spot contaminated product of the absorption coefficient of two kinds of product oils and pipeline batch transportation district, do least square fitting at last, analyze quantitatively the volume ratio of two kinds of product oils in the contaminated product district.Referring to Fig. 8, transverse axis is the volume ratio of 97# gasoline reality in contaminated product, the longitudinal axis is the measured value of 97# gasoline shared percent by volume in contaminated product, Real97 is that the theory of 97# gasoline different proportion is measured curve, Fitted97# is the measurement curve of 97# gasoline shared volume ratio in contaminated product, verify by experiment blending ratio and actual mixture ratio example error average out to 4.3%, can cut accurately and divide contaminated product district in the products pipeline sequential delivery, satisfy the needs in the practical application, verified the feasibility of this method.

The technician is appreciated that accompanying drawing is the schematic diagram of a preferred embodiment, and the invention described above embodiment sequence number does not represent the quality of embodiment just to description.

The above is only preferred embodiment of the present invention, and is in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, is equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (6)

1. a tera-hertz spectra to the composition of product oil and contaminated product and the analytical approach of blending ratio, is characterized in that, said method comprising the steps of:

(1) obtain the Terahertz frequency range, and solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t);

(2) according to described signal s _n(t) determine the time period t that contaminated product occurs in Measuring Time ₁~ t ₂Ask at 0 ~ t respectively ₁In time and t ₂~ t _endProduct oil kind in time interior conduit batch transportation;

(3) in described Terahertz frequency range, to t ₁~ t ₂Absorption coefficient corresponding to measurement order that occurs in time _si(w) carry out least square fitting, find the solution in corresponding contaminated product two kinds of product oils percent by volume separately.

2. a kind of tera-hertz spectra according to claim 1 to the composition of product oil and contaminated product and the analytical approach of blending ratio, is characterized in that, describedly obtains the Terahertz frequency range, and solves the n that repeatedly measures _siThe signal that (1THz) changes with Measuring Time is specially:

1) obtain respectively terahertz time-domain waveform S (t) by filling the sample cuvette and the reference terahertz time-domain waveform R (t) of the empty cuvette by same thickness, to pretreated time-domain signal s ' (t) and R ' (t) do the Fourier transform that obtains sample signal after Fourier transform Fourier transform with reference signal

And both ratios are expressed as amplitude ρ (w) and phase place

The form of product;

2) by described amplitude ρ (w) and described phase place

Find the solution refractive index and the absorption coefficient of sample;

3) obtain the refractive index n of oil product when measuring for the i time _siAnd extract the refractive index of oil product when measuring for the i time at the value n at 1THz frequency place (w) and absorption coefficient si (w), _si(1THz);

4) find the solution described absorption coefficient _si(w) coefficient of distinguish A _α, intercept out A _αChanging value is no more than the described Terahertz frequency range of preset value;

5) in described Terahertz frequency range, solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t).

3. a kind of tera-hertz spectra according to claim 2 to the composition of product oil and contaminated product and the analytical approach of blending ratio, is characterized in that, described pre-service is specially:

Intercept out the time-domain signal part before reflection peak arrives, and in the described time-domain signal part back zero padding that intercepts, obtain pretreated described time-domain signal s ' (t) and R'(t).

4. a kind of tera-hertz spectra according to claim 2 to the composition of product oil and contaminated product and the analytical approach of blending ratio, is characterized in that, and is described in described Terahertz frequency range, solves the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t) be specially:

Utilize the measuring intervals of TIME of measuring order and terahertz time-domain spectroscopy instrument to solve Measuring Time, as transverse axis, take the refractive index amplitude as the longitudinal axis, set up cartesian coordinate system; Solve the n that repeatedly measures _siThe signal s that (1THz) changes with Measuring Time _n(t).

5. a kind of tera-hertz spectra according to claim 1 to the composition of product oil and contaminated product and the analytical approach of blending ratio, is characterized in that, and is described according to described signal s _n(t) determine the time period t that contaminated product occurs in Measuring Time ₁~ t ₂Ask at 0 ~ t respectively ₁In time and t ₂~ t _endProduct oil kind in time interior conduit batch transportation is specially:

1) with described signal s _n(t) amplitude for the first time and last the initial time t that the initial time that changes greater than preset value arrives as contaminated product district in the pipeline batch transportation respectively occurs ₁With contaminated product end of extent moment t ₂

2) will be at 0 ~ t ₁Refractive index corresponding to measurement order that occurs in time is averaged, and obtains

Will be at t ₂~ t _endRefractive index corresponding to measurement order that occurs in time is averaged, and obtains

3) in described Terahertz frequency range, find the solution

With the residual values of four kinds of product oil refractive indexes, product oil corresponding to Minimum Residual difference is 0 ~ t ₁Product oil kind in time interior conduit batch transportation in like manner, is determined at t ₂~ t _endProduct oil kind in time interior conduit batch transportation.

6. a kind of tera-hertz spectra according to claim 1 to the composition of product oil and contaminated product and the analytical approach of blending ratio, is characterized in that, and is described to t ₁~ t ₂Absorption coefficient corresponding to measurement order that occurs in time _si(w) carry out least square fitting, find the solution in corresponding contaminated product two kinds of product oils separately percent by volume be specially:

α _si(w)=c _iα ₁(w)+d _iα ₂(w)，i＝1,2,3，...,n

N measures number of times, α for all that complete in the contaminated product district ₁(w) and α ₂(w) be respectively the absorption coefficient of two kinds of product oils that decision-making goes out, c _iAnd d _iBe respectively the percent by volume of the first product oil and the second product oil in the contaminated product of measuring for the i time.

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