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CN-122016728-A - For capturing CO2Phase separation point detection method and detection system for two-phase absorbent

CN122016728ACN 122016728 ACN122016728 ACN 122016728ACN-122016728-A

Abstract

The invention particularly relates to a method and a system for detecting a split-phase point of a two-phase absorbent for capturing CO 2 , and belongs to the technical field of carbon dioxide capturing. The method comprises the steps of controlling the temperature of an absorbent in a phase separator, irradiating with laser with specific wavelength, receiving forward scattered light within the range of 0.1-0.29 degrees by using a linear array CMOS sensor and converting the forward scattered light into an electric signal to obtain a light intensity sequence I (T), introducing CO 2 to perform absorption-standing circulation, calculating a light intensity relative attenuation rate R (T), monitoring whether the light intensity relative attenuation rate R (T) is continuously lower than a threshold value R_th for reaching a time T_hold, automatically judging a phase separation point, and recording the load of CO 2 . The system comprises corresponding optical detection, signal processing and control analysis modules, realizes objective, real-time and high-precision detection of the split-phase points, and solves the problems of large subjective error, insufficient sensitivity or difficult on-line of the traditional macroscopic method and the traditional instrument method.

Inventors

  • WANG HUANJUN
  • TANG ZHIGANG
  • GUO DONGFANG
  • GUO DONG
  • SUN BEIQI
  • Ben Guoxun
  • LIU LIANBO

Assignees

  • 中国华能集团清洁能源技术研究院有限公司
  • 清华大学

Dates

Publication Date
20260512
Application Date
20260313

Claims (10)

  1. 1. The two-phase absorbent split-phase point detection method for capturing CO 2 is characterized by comprising the following steps of: S1, placing a two-phase absorbent solution to be detected in a transparent phase-splitting reactor, and controlling the temperature of the reactor at a set value; S2, vertically irradiating the absorbent solution in the phase-splitting reactor by adopting a laser light source with the wavelength ranging from 340 nm to 1020 nm; S3, receiving forward scattered light signals generated by the irradiated solution within a scattering angle range of 0.1-0.29 degrees by using a linear array CMOS photoelectric sensor; s4, converting the forward scattered light signal into an electric signal, and obtaining a sequence I (t) of light intensity changing along with time after real-time processing; s5, introducing CO 2 gas into the split-phase reactor for absorption, and alternately performing a circulation process of gas absorption and solution standing; s6, calculating a real-time relative attenuation rate R (T) of the light intensity sequence I (T) relative to the initial baseline light intensity I 0 , monitoring whether the R (T) is continuously lower than a preset attenuation rate threshold value R_th for a preset duration time T_hold, judging that a phase separation point occurs when the condition is met, and recording the CO 2 accumulated absorption load corresponding to the moment.
  2. 2. The method according to claim 1, wherein the step S6 specifically includes: (1) Before introducing CO 2 gas, collecting and calculating the average light intensity of the absorbent solution in a homogeneous stable phase, and taking the average light intensity as the initial baseline light intensity I 0 ; (2) Setting the attenuation rate threshold R_th and the preset duration time T_hold; (3) During CO 2 absorption, R (t) =i (t)/I 0 is calculated in real time; (4) When R (t) is less than or equal to R_th, starting or accumulating timing; (5) When the accumulated timing time reaches T_hold, it is determined that the split phase point occurs.
  3. 3. The detection method according to claim 2, wherein the decay rate threshold r_th is 5% to 20%.
  4. 4. The method according to claim 1 or 2, wherein the wavelength of the laser light source is 650 nm or 980 nm.
  5. 5. The method of claim 1, wherein the two-phase absorbent is a Diethylenetriamine (DETA) -sulfolane-water system.
  6. 6. The method according to claim 5, wherein the mass concentration of diethylenetriamine in the absorbent is not less than 1%, and the mass concentration of sulfolane is not less than 5%.
  7. 7. A detection system for implementing the phase separation point detection method according to any one of claims 1 to 6, characterized by comprising: The optical detection unit comprises a light source module for emitting laser with the wavelength ranging from 340 nm to 1020 nm, a transparent split-phase reactor for containing absorbent solution and controlling the temperature, and a linear array CMOS sensor for accurately receiving forward scattered light with the scattering angle ranging from 0.1 DEG to 0.29 DEG; the signal processing unit is used for conditioning, analog-to-digital converting and collecting the signals output by the sensor; A control and analysis unit configured to execute the split-phase point determination algorithm according to claim 1 or 2, and output a determination result.
  8. 8. The detection system according to claim 7, wherein the light source module is a semiconductor laser diode with a wavelength of 650 nm or 980 nm.
  9. 9. The detection system according to claim 7, wherein the number of pixels of the linear array CMOS sensor is 50 to 500, and the single pixel size of the front filter array is not more than 200 μm by 200 μm.
  10. 10. The system of claim 7, wherein the control and analysis unit is a host computer equipped with dedicated analysis software for displaying light intensity curves in real time, executing a decision algorithm, and recording split phase point data.

Description

Two-phase absorbent split-phase point detection method and detection system for capturing CO 2 Technical Field The invention belongs to the technical field of carbon dioxide trapping, and particularly relates to a method and a system for detecting a split-phase point of a two-phase absorbent for trapping CO 2. Background Currently, liquid-liquid two-phase absorbers are of great interest for their potential in reducing the energy consumption of CO 2 capture and regeneration. The absorbent is generally composed of active amine, phase splitting agent and auxiliary agent, and phase separation occurs after CO 2 is absorbed or heated, so that lean and rich two phases are formed, and efficient enrichment and low-energy regeneration of CO 2 are realized. However, accurately identifying the phase separation starting point is critical to understanding the phase separation mechanism and optimizing the absorption process. At present, an experimental method for observing whether layering occurs or not through naked eyes after introducing CO 2 into a bubbling reaction device and standing is generally adopted for researching a phase separation process of a liquid-liquid two-phase absorbent. The method has the obvious defects of strong subjectivity and poor reproducibility due to complete dependence on experience judgment of experimental staff, is essentially endpoint detection, cannot be dynamically monitored in real time, cannot reflect dynamic evolution of a phase separation process, and has low sensitivity and obvious hysteresis. Aiming at disperse phase detection, the existing instrument analysis method has specific limitations when being applied to a liquid-liquid two-phase absorbent dynamic phase separation process, and is difficult to meet the requirements that although a light reflection method can identify a phase interface, signals of the light reflection method are extremely sensitive to the phase interface which is dynamically formed and continuously changed, severe fluctuation and interference are easy to generate, stability is poor, the light reflection method is not suitable for monitoring a chaotic state at the initial stage of interface generation in real time, sensitivity of an electric characteristic measurement method is insufficient, phase separation initiation cannot be responded in time, a nephelometry method is easy to be interfered by incident light intensity drift and residual micro bubbles or particle impurities in a solution, signal to noise ratio is low, and a spectrophotometry method generally needs to add specific color development or reaction reagents, so that chemical balance of a system per se can be changed, and secondary pollution exists. Therefore, a method for objectively, sensitively, real-time and in-situ detecting the phase separation starting point of a liquid-liquid two-phase absorbent is needed in the art, so as to overcome the defects of subjective observation errors and the existing instrument method in the aspect of dynamic and microscopic detection, and provide a reliable analysis tool for the development and application of the two-phase absorbent. Disclosure of Invention Accordingly, the primary object of the present invention is to overcome the defects of the prior art, and to provide a method and a system for detecting the split-phase point of a two-phase absorbent for capturing CO 2, which can realize objective, high-sensitivity and real-time online detection of the split-phase starting point of a liquid-liquid two-phase absorbent in the process of absorbing CO 2, so as to replace the subjective judgment depending on human eyes, and overcome the problems of low sensitivity, large interference or non-in-situ in the dynamic split-phase detection of the existing instrument method. The invention has the core that the characteristic attenuation of the forward small-angle Mie scattered light signal along with the phase separation is established as a detection physical quantity, and a set of detection system integrating specific light path design, signal processing and quantitative judgment algorithm is constructed, so that the objective, high-sensitivity and real-time on-line judgment of the phase separation point is realized. In order to achieve the above purpose, the technical scheme of the invention is as follows: In a first aspect, the invention discloses a method for detecting a split-phase point of a two-phase absorbent for capturing CO 2, which is characterized in that an absorbent solution is irradiated by laser with specific wavelength, a forward small-angle scattered light signal is collected, and fluctuation characteristics of the signal intensity are analyzed in real time, so that the split-phase point is quantitatively judged. The method specifically comprises the following steps: S1, placing a two-phase absorbent solution to be detected in a transparent phase-splitting reactor, and controlling the temperature of the reactor at a set value; S2, vertically irradiat