CN116046745A - Spectrum processing method and device for gas Raman spectrum - Google Patents
Spectrum processing method and device for gas Raman spectrum Download PDFInfo
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Abstract
The invention provides a spectrum processing method and device of gas Raman spectrum, wherein the method comprises the following steps: acquiring a basic background spectrum; carrying out Raman spectrum detection on the sample gas to obtain an original spectrum of the sample gas; correcting the basic background spectrum to obtain a sample gas background spectrum; obtaining a sample gas initial spectrum according to the sample gas initial spectrum and the sample gas background spectrum; performing baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas; and carrying out normalization treatment on the sample gas correction spectrum to obtain a sample gas Raman spectrum after spectrum treatment. The method provided by the invention can overcome the influence of the change of detection conditions, obviously improve the Raman spectrum accuracy, improve the characteristics of the Raman spectrum peaks of each component of the mixed sample gas and lay a good foundation for the follow-up quantitative analysis of the mixed gas composition.
Description
Technical Field
The invention relates to the technical field of chemometry, in particular to a spectrum processing method of gas Raman spectrum and a spectrum processing device of gas Raman spectrum.
Background
The laser Raman spectrum technology is a molecular structure characterization technology based on Raman scattering effect, can realize nondestructive rapid analysis of samples, has a simple structure, low maintenance cost and simple and convenient operation, and is widely applied to the fields of oil refining, chemical industry, pharmacy and the like.
In order to enhance the intensity of raman signals, researchers at home and abroad propose various schemes such as multiple reflection of excitation light, increase of laser power, artificial pressurization of sample gas, increase of collection angle of raman scattered light and the like. However, the raw raman spectrum actually detected is not only related to the composition of the mixed gas, but also related to many external interference factors (such as the sample gas pressure, the laser power, etc.). It is difficult to ensure that these parameters are constant during online application. In addition, the metal material of the sampling cell and the like can generate corresponding Raman spectrum under the action of laser, and the Raman spectrum is also called as 'background spectrum'. How to eliminate the influence of these interference factors on the spectrum is important, and it directly affects the repeatability and accuracy of the subsequent online analyzer.
Disclosure of Invention
Aiming at the technical problems that interference factors cannot be eliminated and the accuracy of Raman spectrum detection is affected in the prior art, the invention provides a spectrum processing method of gas Raman spectrum and a spectrum processing device of gas Raman spectrum.
To achieve the above object, a first aspect of the present invention provides a spectrum processing method of gas raman spectrum, comprising the steps of: acquiring a basic background spectrum; carrying out Raman spectrum detection on the sample gas to obtain an original spectrum of the sample gas; correcting the basic background spectrum to obtain a sample gas background spectrum; obtaining a sample gas initial spectrum according to the sample gas initial spectrum and the sample gas background spectrum; performing baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas; and carrying out normalization treatment on the sample gas correction spectrum to obtain a sample gas Raman spectrum after spectrum treatment.
Further, the acquiring the basic background spectrum includes: carrying out Raman spectrum detection on background gas to obtain an original spectrum, wherein the background gas comprises air or nitrogen; and removing Raman peaks corresponding to the background gas in the original spectrum to obtain the basic background spectrum.
Further, the correcting the basic background spectrum to obtain a sample gas background spectrum includes: determining a predicted composition of the sample gas; selecting a plurality of reference spectrum regions from the basic background spectrum according to the predicted component, wherein the reference spectrum regions do not comprise Raman peaks of the predicted component; and carrying out sample gas regression on the light intensity of the basic background spectrum in the reference spectrum region and the light intensity of the original sample gas spectrum in the reference spectrum region to obtain the sample gas background spectrum.
Further, the reference spectrum region does not include a raman peak of the predicted component and a degree of change in light intensity between any two of the plurality of reference spectrum regions is greater than a set value.
Further, the degree of light intensity variation between any two reference spectrum regions is obtained by:
wherein C is the light intensity variation, L 1 And L 2 The average light intensity of the two reference spectral regions is calculated.
Further, the performing baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas includes: acquiring a spectrum baseline; and removing the spectrum baseline from the initial spectrum of the sample gas to obtain the sample gas correction spectrum.
Further, the acquiring a spectrum baseline includes: dividing the initial spectrum of the sample gas into a plurality of sections according to the spectrum shape of the initial spectrum of the sample gas; fitting a base line of each section of sample gas initial spectrum by adopting a fitting algorithm corresponding to the spectrum shape of each section of sample gas initial spectrum; the spectrum baseline is obtained according to the baseline of the initial spectrum of each section of sample gas.
Further, the fitting algorithm comprises an iterative filtering algorithm or a polynomial iterative algorithm.
Further, the normalizing the sample gas correction spectrum includes: determining the common components of sample gas and detection gas, wherein the detection gas and the sample gas are continuously collected in the production process; determining a characteristic peak height of the common component in the sample gas correction spectrum; determining the sample gas Raman spectrum according to the sample gas correction spectrum and the characteristic peak height:
wherein N (v) is a sample gas Raman spectrum, S (v) is a sample gas correction spectrum, and P i Is the characteristic peak height.
A second aspect of the present invention provides a spectrum processing apparatus for gas raman spectroscopy, the spectrum processing apparatus comprising: an acquisition unit for acquiring a basic background spectrum; carrying out Raman spectrum detection on the sample gas to obtain an original spectrum of the sample gas; the correction unit is used for correcting the basic background spectrum to obtain a sample gas background spectrum; the background removing unit is used for obtaining a sample gas initial spectrum according to the sample gas initial spectrum and the sample gas background spectrum; the correction unit is used for carrying out baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas; and the normalization processing unit is used for carrying out normalization processing on the sample gas correction spectrum to obtain a sample gas Raman spectrum after spectrum processing.
Through the technical scheme provided by the invention, the invention has at least the following technical effects:
according to the spectrum processing method of the gas Raman spectrum, a basic background spectrum is acquired firstly, then the basic background spectrum is corrected to obtain a sample gas background spectrum, then Raman spectrum detection is carried out on sample gas to obtain a sample gas original spectrum, the sample gas background spectrum is subtracted from the sample gas original spectrum to obtain a sample gas initial spectrum, baseline correction is carried out on the sample gas initial spectrum to obtain a sample gas correction spectrum, and normalization processing is carried out on the sample gas correction spectrum to obtain a sample gas Raman spectrum after spectrum processing. The method provided by the invention can overcome the influence of the change of the detection condition, obviously improve the Raman spectrum accuracy, improve the characteristics of the Raman spectrum peaks of each component of the mixed sample gas and lay a good foundation for the follow-up quantitative analysis of the mixed gas composition.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain, without limitation, the embodiments of the invention. In the drawings:
FIG. 1 is a flowchart of a spectrum processing method of gas Raman spectrum provided by an embodiment of the invention;
fig. 2 is a schematic diagram of a gas raman spectrum test platform used in a spectrum processing method of gas raman spectrum according to an embodiment of the present invention;
FIG. 3 shows background spectrum and N in a spectrum processing method of gas Raman spectrum according to an embodiment of the invention 2 A schematic representation of the spectrum;
FIG. 4 is a schematic diagram of an original spectrum and a basic background spectrum of a sample gas in a spectrum processing method of a gas Raman spectrum according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a partial amplification of a reference spectrum region in a spectrum processing method of gas Raman spectrum according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a correspondence between the light intensity of the original spectrum of the sample gas in the reference spectrum region and the light intensity of the basic background spectrum in the reference spectrum region in the spectrum processing method of the gas Raman spectrum provided by the embodiment of the invention;
FIG. 7 is a schematic diagram of a background spectrum of a sample gas in a method for processing a spectrum of a gas Raman spectrum according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of an initial spectrum of a sample gas in a method for processing a spectrum of a gas Raman spectrum according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a partial amplification of an initial spectrum of a sample gas in a method for processing a spectrum of a gas Raman spectrum according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of a spectrum baseline in a spectrum processing method of gas Raman spectrum according to an embodiment of the present invention;
FIG. 11 is a schematic diagram of a sample gas calibration spectrum in a method for processing a gas Raman spectrum according to an embodiment of the present invention;
FIG. 12 is a schematic diagram of a sample gas Raman spectrum in a method for processing a gas Raman spectrum according to an embodiment of the present invention;
FIG. 13 is a schematic diagram of a partial amplification of a sample gas Raman spectrum in a method for processing a spectrum of a gas Raman spectrum according to an embodiment of the present invention;
fig. 14 is a schematic diagram of a spectrum processing apparatus for gas raman spectroscopy according to an embodiment of the present invention.
Detailed Description
The following describes the detailed implementation of the embodiments of the present invention with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
In the present invention, unless otherwise indicated, terms of orientation such as "upper, lower, top, bottom" are used generally with respect to the orientation shown in the drawings or with respect to the positional relationship of the various components with respect to one another in the vertical, vertical or gravitational directions.
The ethylene cracking furnace is a production device of important basic organic chemical raw materials such as ethylene, propylene, butadiene and the like, and the material analysis of the ethylene cracking furnace is very important. The gas phase material (pyrolysis gas) at the outlet contains H 2 、CH 4 、C 2 H 6 、C 2 H 4 、C 3 H 8 、C 3 H 6 And (3) light components. The content of the components in the pyrolysis gas is measured, so that the pyrolysis depth of the pyrolysis furnace and the distribution condition of pyrolysis products can be known, and the optimization of technological parameters is guided. In the prior art, components of pyrolysis gas are analyzed by Raman spectrum, pure Ar or other inert gases are introduced into a closed sampling tube, and the inert gases have no Raman response, so that the spectrum obtained by detection is a background spectrum; and for the sample gas to be detected, the original spectrum is firstly detected, and then the background spectrum is subtracted, so that the effective Raman spectrum can be obtained. However, the background spectrum is not constant. Experiments show that: the background spectrum is related to the laser power, the sample pressure temperature, etc. In continuous online applications, there are significant limitations to the above-described methods.
In addition, gas raman spectroscopy is ubiquitous in terms of spectral baseline drift up and down, with the magnitude of the baseline drift being related to a number of external interfering factors (such as laser power, integration time, sample gas pressure and temperature, etc.), and the magnitude of the baseline drift being different throughout the spectrum. These external disturbances directly affect the heights and peak areas of the raman characteristic peaks of the components. In order to improve the repeatability of the subsequent raman quantitative analysis, the original raman is required to be pretreated, so that the pretreated spectrum is not basically influenced by the measurement conditions, but only related to the composition content of the mixed gas.
For the above problems, the method for processing the gas raman spectrum provided by the invention mainly comprises the following steps: dynamic correction and subtraction of background spectrum, raman spectrum baseline correction and normalization. By the method provided by the invention, the influence of measurement condition fluctuation on the Raman spectrum of the gas can be basically eliminated, and the accuracy of the Raman spectrum is obviously improved.
The invention will be described in detail below with reference to the drawings in connection with embodiments.
Referring to fig. 1, an embodiment of the present invention provides a method for processing a gas raman spectrum, which includes the following steps: s101: acquiring a basic background spectrum;
further, the acquiring the basic background spectrum includes: carrying out Raman spectrum detection on background gas to obtain an original spectrum, wherein the background gas comprises air or nitrogen; and removing Raman peaks corresponding to the background gas in the original spectrum to obtain the basic background spectrum.
In particular, in embodiments of the invention, air or pure N 2 Introducing into a sampling tube, detecting to obtain an original spectrum, and subtracting air or N in the original spectrum 2 Raman peak, thereby obtaining basic background spectrum B 0(v) 。
By the method provided by the invention, the air or N which is easy to obtain 2 Detecting, and deducting air or pure N from the original spectrum 2 The Raman peak of the spectrum can obtain the basic background spectrum, and the convenience of acquiring the basic background spectrum is improved.
S102: carrying out Raman spectrum detection on the sample gas to obtain an original spectrum of the sample gas;
s103: correcting the basic background spectrum to obtain a sample gas background spectrum;
further, the correcting the basic background spectrum to obtain a sample gas background spectrum includes: determining a predicted composition of the sample gas; selecting a plurality of reference spectrum regions from the basic background spectrum according to the predicted component, wherein the reference spectrum regions do not comprise Raman peaks of the predicted component; and carrying out sample gas regression on the light intensity of the basic background spectrum in the reference spectrum region and the light intensity of the original sample gas spectrum in the reference spectrum region to obtain the sample gas background spectrum.
Further, the reference spectrum region does not include a raman peak of the predicted component and a degree of change in light intensity between any two of the plurality of reference spectrum regions is greater than a set value.
Further, the degree of light intensity variation between any two reference spectrum regions is obtained by:
wherein C is the light intensity variation, L 1 And L 2 The average light intensity of the two reference spectral regions is calculated.
Specifically, in the embodiment of the present invention, the predicted composition of the sample gas is predicted first in order to ensure the basic background spectrum B 0 (v) Reliability of correction in the basic background spectrum B 0 (v) The reference spectrum region does not comprise a Raman peak of a predicted component, and the light intensity variation degree between any two reference spectrum regions in the plurality of reference spectrum regions is larger (larger than a set value). In the basic background spectrum B 0 (v) The light intensity in the reference spectrum region is taken as an input vector, the light intensity of the original spectrum I (v) of the sample gas in the reference spectrum region is taken as an output vector, the gain K and the intercept B are obtained through linear regression, and the background spectrum B (v) =KB of the sample gas is obtained 0 (v)+b。
S104: obtaining a sample gas initial spectrum according to the sample gas initial spectrum and the sample gas background spectrum;
specifically, in the embodiment of the present invention, the sample gas background spectrum B (v) is subtracted from the sample gas original spectrum I (v) to obtain the sample gas original spectrum a (v), i.e., a (v) =i (v) -B (v).
S105: performing baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas;
further, the performing baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas includes: acquiring a spectrum baseline; and removing the spectrum baseline from the initial spectrum of the sample gas to obtain the sample gas correction spectrum.
Further, the acquiring a spectrum baseline includes: dividing the initial spectrum of the sample gas into a plurality of sections according to the spectrum shape of the initial spectrum of the sample gas; fitting a base line of each section of sample gas initial spectrum by adopting a fitting algorithm corresponding to the spectrum shape of each section of sample gas initial spectrum; the spectrum baseline is obtained according to the baseline of the initial spectrum of each section of sample gas.
Further, the fitting algorithm comprises an iterative filtering algorithm or a polynomial iterative algorithm.
Specifically, in the embodiment of the invention, the spectrum shape of the sample gas initial spectrum A (v) is obtained, the sample gas initial spectrum A (v) is divided into a plurality of sections according to the spectrum shape of the sample gas initial spectrum A (v), the peak half width is narrower and is divided into one section, and the peak half width is wider and is divided into one section. And fitting the base line by adopting an iterative filtering algorithm on the section with the narrower peak half-width, fitting the base line by adopting a polynomial iterative algorithm on the section with the wider peak half-width, and combining the two sections of base lines to obtain the spectrum base line BL (v). The spectrum baseline BL (v) is subtracted from the sample gas initial spectrum a (v) to obtain a sample gas corrected spectrum S (v), i.e., S (v) =a (v) -BL (v).
S106: and carrying out normalization treatment on the sample gas correction spectrum to obtain a sample gas Raman spectrum after spectrum treatment.
Further, the normalizing the sample gas correction spectrum includes: determining the common components of sample gas and detection gas, wherein the detection gas and the sample gas are continuously collected in the production process; determining a characteristic peak height of the common component in the sample gas correction spectrum; determining the sample gas Raman spectrum according to the sample gas correction spectrum and the characteristic peak height:
wherein N (v) is a sample gas Raman spectrum, S (v) is a sample gas correction spectrum, and P i Is the characteristic peak height.
Specifically, in the embodiment of the invention, the common components contained in a plurality of samples (sample gas and detection gas) continuously collected in the production process are determined, the peak heights of characteristic peaks of the common components in the sample gas correction spectra of the plurality of samples are determined, and one common component with a higher peak height, such as the component with the highest peak height, or the component with the second highest peak height, is selected. Determining the peak height of the common component as a characteristic peak height P in a sample gas correction spectrum S (v) i Let N (v) =s (v)/P i Obtaining the final processed sample gas Raman spectrum N (v).
The spectrum processing method of the gas Raman spectrum can overcome the influence of the change of detection conditions, obviously improve the Raman spectrum accuracy, improve the characteristics of the Raman spectrum peaks of each component of the mixed sample gas and lay a good foundation for the follow-up quantitative analysis of the mixed gas composition.
The method provided by the invention is not only suitable for Raman spectrum treatment of pyrolysis gas, but also suitable for Raman spectrum treatment of other gases.
Example 1
Referring to fig. 2, fig. 2 is a schematic diagram of a gas raman spectrum testing platform used in the present invention. The main optical components are: lasers, optical fibers (excitation and collection fibers), raman probes, and fiber spectrometers. The laser is a laser with a center wavelength of 532 nm; the Raman probe is a 532nm optical fiber probe; the optical fiber spectrometer is a TEC refrigeration optical fiber spectrometer.
The measurement process of the system is as follows: intermittently or continuously introducing the sample gas into the sampling tube; the laser emits monochromatic laser, the monochromatic laser is conducted to the Raman probe through the excitation optical fiber, the Raman probe irradiates a sample after focusing, and the generated Raman scattered light is collected by the Raman probe and then is conducted back to the optical fiber spectrometer through the collection optical fiber; the Raman scattered light is subjected to grating light splitting, photoelectric detection and analog-to-digital conversion by the optical fiber spectrometer to be converted into a spectrum digital signal, and the spectrum digital signal is transmitted to a PC by the optical fiber spectrometer to be analyzed by Raman spectrum analysis software.
The background spectrum is mainly caused by the laser excitation of the stainless steel inner cavity in the Raman detection pool, and is irrelevant to the composition of the sample gas. Because inert gases such as Ar gas and the like have no Raman signal, the inert gases can be introduced into a sampling tube in advance, the original spectrum of the inert gases is obtained by using the gas Raman spectrum testing platform, and linear interpolation is carried out in the whole Raman displacement range, so that the basic background spectrum is obtained. In addition, air or N may be used 2 Introducing gas into a sampling tube, and detecting to obtain an original spectrum by using the gas Raman spectrum test platform; due to N 2 Gas and O 2 The gas Raman peak is single peak, which is respectively at 2331 cm and 1556cm -1 These 2 peaks in the original spectrum can be subtracted. N (N) 2 The original spectrum of (2) is shown in solid lines in FIG. 3, which still contains a small amount of sample tube residue O 2 Qi, deduct N 2 With O 2 Basic background spectrum B obtained after the peak 0 (v) As indicated by the dashed lines in fig. 3.
Carrying out Raman spectrum detection on sample gas of ethylene pyrolysis gas to obtain an original spectrum I (v) of the sample gas;
sample gas raw spectrum I (v) and basic background spectrum B of sample gas 0 (v) As shown in fig. 4. In combination with the predicted component spectrum peaks possibly contained in the pyrolysis gas, in the basic background spectrum B 0 (v) A plurality of reference spectrum regions are selected, the reference spectrum regions do not comprise Raman peaks of predicted components, the light intensity variation degree between any two reference spectrum regions in the plurality of reference spectrum regions is larger, please refer to fig. 5, the reference spectrum regions in fig. 5 are [ 440-490, 650-700 ]]cm -1 Is a region of (a) in the above-mentioned region(s). For the spectrum of the pyrolysis gas, the stray spectrum is not in contact with the basic background spectrum B under the influence of the measurement conditions 0 (v) Completely identical, but spectrally identical.
For a certain ethylene cracking experimental process, 80 cracking gas Raman spectra are continuously collected (the sampling period is 70 s). Specific procedures are described in detail below using the original spectrum I (v) of sample gas 50 as an example. The main components of the sample gas are as follows: 10.09% H 2 、22.65％CH 4 、3.62％C 2 H 6 、43.46％C 2 H 4 、0.35％C 3 H 8 、11.54％C 3 H 6 。
Please refer to fig. 6, in order to obtain a basic background spectrum B 0 (v) The light intensity in the reference spectrum region is taken as an input vector, the light intensity of the original spectrum I (v) of the sample gas in the reference spectrum region is taken as an output vector, the gain K and the intercept B obtained by linear regression are 0.9152 and 91.5565 respectively, and the sample gas background spectrum B (v) =KB of the sample gas shown in fig. 7 is obtained 0 (v)+b。
Referring to fig. 8 and 9, the sample gas background spectrum B (v) is subtracted from the sample gas original spectrum I (v) to obtain a sample gas original spectrum a (v), i.e., a (v) =i (v) -B (v).
By subtracting the background spectrum of the sample gas contained in the original spectrum of the sample gas, the spectral shape is significantly improved, except that there is some drift in the bottom of its spectrum (also referred to as "baseline drift"). A segmented baseline correction is therefore employed for the initial spectrum of the sample gas.
Dividing the sample gas initial spectrum A (v) into 300-2200 and 2201-3100 cm according to the spectrum shape of the sample gas initial spectrum A (v) -1 And (5) multiple sections. For the 1 st spectral band, the half width of the filtering window is 200cm -1 Fitting a baseline by adopting an iterative S-G filtering algorithm; for the 2 nd spectral band, the baseline is fitted by using a polynomial iterative algorithm, and the order of the polynomial is 1 st order. The final fit resulted in a spectrum baseline BL (v) as shown by the dashed line in fig. 10, and the baseline corrected sample gas spectrum was S (v) =a (v) -BL (v) as shown in fig. 11.
Determining the common components contained in a plurality of samples continuously collected in the production process, determining the peak heights of characteristic peaks of the common components in sample gas correction spectrums of the plurality of samples, selecting one common component with higher peak height, and selecting H in the embodiment 2 In the sample gas correction spectrum S (v), H is 2 As the characteristic peak height P i . Let N (v) =s (v)/P i The final processed sample gas raman spectrum N (v) was obtained as shown in fig. 12.
In FIG. 12 at 1345cm -1 Is 4.1944. As shown in FIG. 13, the partial magnification of the Raman spectrum of the sample gas is 22002250cm -1 The standard deviation of the spectrum is 0.0022, which reflects the mean of the noise levels. For the ethylene raman peak, its signal to noise ratio is 4.1944/(3×0.0022) =700:1; for H 2 Peak with signal-to-noise ratio of 1.0/(3×0.0022) =150:1, it can be seen that the raman signal is stronger H for pure components 2 And C 2 H 4 The theoretical detection limit of the isoolefin component is close to 0.07 percent.
Referring to fig. 14, a second aspect of the present invention provides a spectrum processing apparatus for gas raman spectroscopy, the spectrum processing apparatus for gas raman spectroscopy comprising: an acquisition unit for acquiring a basic background spectrum; carrying out Raman spectrum detection on the sample gas to obtain an original spectrum of the sample gas; the correction unit is used for correcting the basic background spectrum to obtain a sample gas background spectrum; the background removing unit is used for obtaining a sample gas initial spectrum according to the sample gas initial spectrum and the sample gas background spectrum; the correction unit is used for carrying out baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas; and the normalization processing unit is used for carrying out normalization processing on the sample gas correction spectrum to obtain a sample gas Raman spectrum after spectrum processing.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
Claims (10)
1. A method of spectral processing of gas raman spectroscopy, the method comprising:
acquiring a basic background spectrum;
carrying out Raman spectrum detection on the sample gas to obtain an original spectrum of the sample gas;
correcting the basic background spectrum to obtain a sample gas background spectrum;
obtaining a sample gas initial spectrum according to the sample gas initial spectrum and the sample gas background spectrum;
performing baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas;
and carrying out normalization treatment on the sample gas correction spectrum to obtain a sample gas Raman spectrum after spectrum treatment.
2. The method of claim 1, wherein the acquiring a primary background spectrum comprises:
carrying out Raman spectrum detection on background gas to obtain an original spectrum, wherein the background gas comprises air or nitrogen;
and removing Raman peaks corresponding to the background gas in the original spectrum to obtain the basic background spectrum.
3. The method of claim 2, wherein said modifying the basic background spectrum to obtain a sample gas background spectrum comprises:
determining a predicted composition of the sample gas;
selecting a plurality of reference spectrum regions from the basic background spectrum according to the predicted component, wherein the reference spectrum regions do not comprise Raman peaks of the predicted component;
and carrying out sample gas regression on the light intensity of the basic background spectrum in the reference spectrum region and the light intensity of the original sample gas spectrum in the reference spectrum region to obtain the sample gas background spectrum.
4. A method according to claim 3, wherein the reference spectral region does not include a raman peak of the predicted component and the degree of intensity variation between any two of the plurality of reference spectral regions is greater than a set point.
5. The method according to claim 4, wherein the degree of intensity variation between any two reference spectral regions is obtained by:
wherein C is the light intensity variation, L 1 And L 2 The average light intensity of the two reference spectral regions is calculated.
6. The method of claim 5, wherein said baseline correcting said initial sample gas spectrum to obtain a sample gas corrected spectrum comprises:
acquiring a spectrum baseline;
and removing the spectrum baseline from the initial spectrum of the sample gas to obtain the sample gas correction spectrum.
7. The method of claim 6, wherein the obtaining a spectral baseline comprises:
dividing the initial spectrum of the sample gas into a plurality of sections according to the spectrum shape of the initial spectrum of the sample gas;
fitting a base line of each section of sample gas initial spectrum by adopting a fitting algorithm corresponding to the spectrum shape of each section of sample gas initial spectrum;
the spectrum baseline is obtained according to the baseline of the initial spectrum of each section of sample gas.
8. The method of claim 7, wherein the fitting algorithm comprises an iterative filtering algorithm or a polynomial iterative algorithm.
9. The method of claim 8, wherein normalizing the sample gas correction spectrum comprises:
determining the common components of sample gas and detection gas, wherein the detection gas and the sample gas are continuously collected in the production process;
determining a characteristic peak height of the common component in the sample gas correction spectrum;
determining the sample gas Raman spectrum according to the sample gas correction spectrum and the characteristic peak height:
wherein N (v) is a sample gas Raman spectrum, S (v) is a sample gas correction spectrum, and P i Is the characteristic peak height.
10. A spectrum processing apparatus for gas raman spectroscopy, the spectrum processing apparatus comprising:
an acquisition unit for acquiring a basic background spectrum; carrying out Raman spectrum detection on the sample gas to obtain an original spectrum of the sample gas;
the correction unit is used for correcting the basic background spectrum to obtain a sample gas background spectrum;
the background removing unit is used for obtaining a sample gas initial spectrum according to the sample gas initial spectrum and the sample gas background spectrum;
the correction unit is used for carrying out baseline correction on the initial spectrum of the sample gas to obtain a corrected spectrum of the sample gas;
and the normalization processing unit is used for carrying out normalization processing on the sample gas correction spectrum to obtain a sample gas Raman spectrum after spectrum processing.
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