Hydrocarbon water dew point measuring method and system based on OCT scanning cold mirror

Abstract

The invention discloses a hydrocarbon water dew point measurement method and system based on an OCT scanning cold mirror, which is applied to the technical field of hydrocarbon water dew point measurement and comprises the following steps: acquiring a dew point condensation image on a cooling mirror surface under OCT scanning; calculating the chromaticity of the dew point condensation image according to a CIEL * a * b * chromatic aberration formula, identifying a hydrocarbon water dew point, and training a hydrocarbon water dew point identification model based on an artificial neural network; and inputting a to-be-measured dew point condensation image to the hydrocarbon water dew point identification model to obtain a hydrocarbon water dew point identification result, and measuring the current dew point temperature. According to the method, on the basis of the color difference between the water dew point condensation film and the hydrocarbon dew point condensation film formed on the cooling mirror surface under OCT scanning, the chromaticity of the dew point condensation image is calculated and the hydrocarbon water dew point is identified by further adopting a CIEL * a * b * color difference formula, so that the hydrocarbon water dew point identification and measurement precision is effectively improved, and the subjectivity is eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrocarbon water dew point measurement, and in particular to a hydrocarbon water dew point measurement method and system based on an OCT scanning cold mirror. Background Art

[0002] Liquefied natural gas (LNG) is a high-quality, clean and efficient energy source. It is a liquid substance formed by purifying gaseous natural gas and cooling it to -162°C in a cryogenic device. The dew point of natural gas is divided into water dew point and hydrocarbon dew point, which is an important indicator to control the generation of liquid substances during the storage and transportation of natural gas.

[0003] In the prior art, infrared absorption spectroscopy is usually used to distinguish hydrocarbon dew point from water dew point, but this method is difficult to distinguish, especially when the hydrocarbon dew point condenses first, it is particularly easy to cover the water dew point, causing measurement errors; at the same time, when the hydrocarbon dew point and the water dew point coexist, it is also difficult to distinguish, and the cost of related equipment is very high. Some also use high-definition cameras to take pictures for identification, but this method has very high requirements on the pixels of the camera, and the camera is particularly susceptible to contamination. When dust or oil mist adheres to the lens, it will cause measurement difficulties. The method of using gas chromatography to measure the components in natural gas and then calculating the hydrocarbon dew point through mathematical calculations not only has poor real-time measurement, but also has large errors due to the use of mathematical calculation methods.

[0004] Therefore, how to provide a hydrocarbon water dew point measurement method and system based on an OCT scanning cold mirror that can quickly and accurately distinguish and measure hydrocarbon water dew point is a problem that those skilled in the art urgently need to solve. Summary of the invention

[0005] In view of this, the present invention proposes a hydrocarbon water dew point measurement method and system based on OCT scanning cold mirror.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for measuring hydrocarbon water dew point based on an OCT scanning cold mirror, comprising:

[0008] Step (1): obtaining a dew point condensation image on the cooling mirror under OCT scanning;

[0009] Step (2): Calculate the chromaticity of the dew point condensation image according to the CIEL*a*b* color difference formula, identify the hydrocarbon water dew point, and train a hydrocarbon water dew point recognition model based on an artificial neural network;

[0010] Step (3): input the dew point condensation image to be measured into the hydrocarbon water dew point recognition model, obtain the hydrocarbon water dew point recognition result, and measure the current dew point temperature.

[0011] Optionally, in step (1), the incident angle of the OCT scan is set to 45-60 degrees.

[0012] Optionally, in step (1), OCT scanning uses infrared light with a central wavelength of 1060 nm as the scanning light source.

[0013] Optionally, in step (1), the cooling mirror is gold-plated copper.

[0014] Optionally, in step (2), the CIEL*a*b* color difference formula is as follows:

[0015] ΔE*=(ΔL* 2 +Δa* 2 +Δb* 2 ) 1 / 2 ;

[0016] L*=116(Y / Y 0 ) 1 / 3 -16;

[0017] a*=500[(X / X 0 ) 1 / 3 -(Y / Y 0 ) 1 / 3 ];

[0018] b*=200[(Y / Y 0 ) 1 / 3 -(Z / Z 0 ) 1 / 3 ];

[0019] Among them, L* is the psychological brightness; a* and b* are the psychological chromaticity; X, Y, and Z are the three stimulus values ​​of the object; X 0 , Y 0 , Z 0 It is the tristimulus value of CIE standard illuminant.

[0020] Optionally, in step (3), the current dew point temperature is measured by a high-precision platinum resistor.

[0021] Optionally, the method further includes: after measuring the current dew point temperature, dissipating heat through a three-stage Peltier heat exchanger and a radiator.

[0022] The present invention also provides a hydrocarbon water dew point measurement system based on an OCT scanning cold mirror using the hydrocarbon water dew point measurement method based on an OCT scanning cold mirror, comprising:

[0023] Image acquisition module: used to obtain the dew point condensation image on the cooling mirror under OCT scanning;

[0024] Model training module: used to calculate the chromaticity of the dew point condensation image according to the CIEL*a*b* color difference formula, identify the hydrocarbon water dew point, and train the hydrocarbon water dew point recognition model based on artificial neural network;

[0025] Temperature measurement module: used to input the dew point condensation image to be measured into the hydrocarbon water dew point recognition model, obtain the hydrocarbon water dew point recognition result, and measure the current dew point temperature.

[0026] It can be seen from the above technical solutions that, compared with the prior art, the present invention proposes a hydrocarbon water dew point measurement method and system based on an OCT scanning cold mirror. Based on the color difference between the water dew point condensation film and the hydrocarbon dew point condensation film formed on the cooling mirror surface under OCT scanning, and further using the CIEL*a*b* color difference formula to calculate the chromaticity of the dew point condensation image, the hydrocarbon water dew point is identified, the hydrocarbon water dew point identification measurement accuracy is improved, and subjectivity is eliminated. An artificial neural network is used to train a hydrocarbon water dew point identification model based on hydrocarbon water dew point chromaticity difference, further improving the identification measurement efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 It is a schematic diagram of the method flow of the present invention.

[0029] Figure 2 It is a schematic diagram of the water dew point condensation film of the present invention.

[0030] Figure 3 It is a schematic diagram of the hydrocarbon dew point condensation film of the present invention.

[0031] Figure 4 It is a schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] Embodiment 1 of the present invention discloses a method for measuring hydrocarbon water dew point based on an OCT scanning cold mirror, such as Figure 1 As shown, including:

[0035] Step (1): Obtain a dew point condensation image on the cooling mirror under OCT scanning; OCT scanning cold mirror is a good non-destructive testing method. During the measurement process, the hydrocarbon water dew point can be distinguished based on the color difference of the condensation film formed on the mirror surface. The detector does not need to directly contact the sample, so it is not easily contaminated, reducing the amount of maintenance during use.

[0036] There is a large color difference between the water dew point condensation film and the hydrocarbon dew point condensation film formed on the cooling mirror under OCT scanning. Specifically, due to the heavy hydrocarbon component, it condenses on the mirror to form a colorful film, which is very different from water condensation under OCT scanning. Figure 2 As shown; hydrocarbon dew point condensation film, such as Figure 3 shown.

[0037] According to the analytical expression of Seidel aberration, the first-order imaging formula is obtained from the Taylor decomposition of trigonometric functions, as follows:

[0038]

[0039] Among them, θ is the incident angle. It is easy to see that the larger the incident angle, the greater the influence of sinθ on the second term and the subsequent terms of the first-order imaging formula. That is, the larger the incident angle, the more it deviates from the first-order perfect imaging. In addition, according to Snell's law n 1 sinθ 1 =n 2 sinθ 2 , the larger the incident angle, the larger the refraction angle and scattering range. Therefore, it can be concluded that: the larger the incident angle, the larger the aberration / chromatic aberration, and the higher the accuracy of the present invention in identifying the hydrocarbon water dew point based on chromatic aberration. Based on this, while taking into account the convenience of building the optical path system, the incident angle of the OCT scan of the present invention is set to 45-60 degrees, and further set to 55 degrees.

[0040] Since the larger the bandwidth of the scanning light source, the better the depth resolution, that is, the higher the accuracy of the present invention in identifying the hydrocarbon water dew point based on chromatic aberration, based on this, after fully considering the absorption characteristics of water in the infrared band, the OCT scanning of the present invention adopts infrared light with a central wavelength of 1060nm as the scanning light source (light in this band is not easily absorbed by water and is suitable for observing water dew point and hydrocarbon dew point).

[0041] The cooling mirror is gold-plated copper.

[0042] Step (2): Calculate the chromaticity of the dew point condensation image according to the CIEL*a*b* color difference formula, identify the hydrocarbon water dew point, and train a hydrocarbon water dew point recognition model based on an artificial neural network;

[0043] In order to further eliminate the subjectivity of hydrocarbon water dew point identification based on the color difference between the water dew point condensation film and the hydrocarbon dew point condensation film under OCT scanning, the chromaticity of the dew point condensation image is calculated according to the CIEL*a*b* color difference formula, and the hydrocarbon water dew point is identified based on the chromaticity of the dew point condensation image, further improving the measurement accuracy of hydrocarbon water dew point identification. At the same time, in order to further improve the efficiency and accuracy of identification measurement, an artificial neural network is used to train the hydrocarbon water dew point identification model based on the hydrocarbon water dew point chromaticity difference.

[0044] The CIEL*a*b* color difference formula is as follows:

[0045] ΔE*=(ΔL* 2 +Δa* 2 +Δb* 2 ) 1 / 2 ;

[0046] L*=116(Y / Y 0 ) 1 / 3 -16;

[0047] a*=500[(X / X 0 ) 1 / 3 -(Y / Y 0 ) 1 / 3 ];

[0048] b*=200[(Y / Y 0 ) 1 / 3 -(Z / Z 0 ) 1 / 3 ];

[0049] Among them, L* is the psychological brightness; a* and b* are the psychological chromaticity; X, Y, and Z are the three stimulus values ​​of the object; X 0 , Y 0 , Z 0 is the tristimulus value of the CIE standard illuminant; X / X 0 、Y / Y 0 、Z / Z 0 >0.008856.

[0050] Step (3): input the dew point condensation image to be measured into the hydrocarbon water dew point recognition model, obtain the hydrocarbon water dew point recognition result, and measure the current dew point temperature.

[0051] The current dew point temperature is measured by a high-precision platinum resistor, and after measuring the current dew point temperature, heat is dissipated through a three-stage Peltier heat exchanger and a radiator.

[0052] Embodiment 2:

[0053] Embodiment 2 of the present invention discloses a hydrocarbon water dew point measurement system based on an OCT scanning cold mirror using the hydrocarbon water dew point measurement method based on an OCT scanning cold mirror described in Embodiment 1, comprising:

[0054] Image acquisition module: used to obtain the dew point condensation image on the cooling mirror under OCT scanning;

[0055] Model training module: used to calculate the chromaticity of the dew point condensation image according to the CIEL*a*b* color difference formula, identify the hydrocarbon water dew point, and train the hydrocarbon water dew point recognition model based on artificial neural network;

[0056] Temperature measurement module: used to input the dew point condensation image to be measured into the hydrocarbon water dew point recognition model, obtain the hydrocarbon water dew point recognition result, and measure the current dew point temperature.

[0057] The embodiment of the present invention discloses a hydrocarbon water dew point measurement method and system based on an OCT scanning cold mirror. Based on the color difference between the water dew point condensation film and the hydrocarbon dew point condensation film formed on the cooling mirror surface under OCT scanning, the chromaticity of the dew point condensation image is calculated by further using the CIEL*a*b* color difference formula to identify the hydrocarbon water dew point, improve the hydrocarbon water dew point identification measurement accuracy, eliminate subjectivity, and use an artificial neural network to train a hydrocarbon water dew point identification model based on the hydrocarbon water dew point chromaticity difference, further improving the identification measurement efficiency and accuracy.

[0058] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0059] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for measuring hydrocarbon water dew point based on OCT scanning chilled mirror, It is characterized in that include: Step (1): obtaining a dew point condensation image on the cooling mirror under OCT scanning; Step (2): calculating the chromaticity of the dew point condensation image according to the CIEL*a*b* color difference formula, identifying the hydrocarbon water dew point, and training a hydrocarbon water dew point recognition model based on an artificial neural network; Step (3): input the dew point condensation image to be measured into the hydrocarbon-water dew point recognition model, obtain the hydrocarbon-water dew point recognition result, and measure the current dew point temperature.

2. The hydrocarbon water dew point measurement method based on OCT scanning cold mirror according to claim 1, It is characterized in that In step (1), the incident angle of the OCT scan is set to 45-60 degrees.

3. The hydrocarbon water dew point measurement method based on OCT scanning cold mirror according to claim 1, It is characterized in that In step (1), the OCT scanning uses infrared light with a central wavelength of 1060 nm as the scanning light source.

4. The hydrocarbon water dew point measurement method based on OCT scanning cold mirror according to claim 1, It is characterized in that In step (1), the cooling mirror is gold-plated copper.

5. The hydrocarbon water dew point measurement method based on OCT scanning cold mirror according to claim 1, It is characterized in that In step (2), the CIEL*a*b* color difference formula is as follows: ΔE*=(ΔL* 2 +Δa* 2 +Δb* 2 ) 1 / 2 ; L*=116(Y / Y 0 ) 1 / 3 -16; a*=500[(X / X 0 ) 1 / 3 -(Y / Y 0 ) 1 / 3 ]; b*=200[(Y / Y 0 ) 1 / 3 -(Z / Z 0 ) 1 / 3 ]; Among them, L* is the psychological brightness; a* and b* are the psychological chromaticity; X, Y, and Z are the three stimulus values ​​of the object; X 0 , Y 0 , Z 0 It is the tristimulus value of CIE standard illuminant.

6. The hydrocarbon water dew point measurement method based on OCT scanning cold mirror according to claim 1, It is characterized in that In step (3), the current dew point temperature is measured by a high-precision platinum resistor.

7. The hydrocarbon water dew point measurement method based on OCT scanning cold mirror according to claim 1, It is characterized in that Also includes: After measuring the current dew point temperature, heat is dissipated through a three-stage Peltier heat exchanger and a radiator.

8. A hydrocarbon water dew point measurement system based on an OCT scanning cold mirror using the hydrocarbon water dew point measurement method based on an OCT scanning cold mirror according to any one of claims 1 to 4, It is characterized in that include: Image acquisition module: used to obtain the dew point condensation image on the cooling mirror under OCT scanning; Model training module: used to calculate the chromaticity of the dew point condensation image according to the CIEL*a*b* color difference formula, identify the hydrocarbon water dew point, and train the hydrocarbon water dew point identification model based on the artificial neural network; Temperature measurement module: used to input the dew point condensation image to be measured into the hydrocarbon-water dew point recognition model, obtain the hydrocarbon-water dew point recognition result, and measure the current dew point temperature.

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