Detection method and detection system for phase splitting point of two-phase absorbent for capturing CO2

Abstract

The invention particularly relates to a method and a system for detecting a phase splitting point of a two-phase absorbent for capturing CO2, and belongs to the technical field of carbon dioxide capturing. The method comprises the following steps: controlling the temperature of an absorbent in a phase splitter, and irradiating with laser with a specific wavelength; a linear array CMOS sensor is used for receiving forward scattered light in the range of 0.1-0.29 degrees and converting the forward scattered light into an electric signal, and a light intensity sequence I (t) is obtained; cO2 is introduced for absorption-standing circulation; by calculating the light intensity relative attenuation rate R (t) and monitoring whether the light intensity relative attenuation rate R (t) is continuously lower than the threshold value Rth for reaching the time Thold or not, the phase splitting point is automatically judged, and the CO2 load is recorded. The system comprises a corresponding optical detection module, a signal processing module and a control analysis module, objective, real-time and high-precision detection of phase splitting points is achieved, and the problems that a traditional naked eye method is large in subjective error, and an existing instrument method is insufficient in sensitivity or difficult to be online are solved.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide capture technology, specifically relating to a method and system for detecting the phase separation point of a two-phase absorbent used for capturing CO2. Background Technology

[0002] Currently, liquid-liquid two-phase absorbents are attracting significant attention due to their potential in reducing energy consumption during CO2 capture and regeneration. These absorbents typically consist of active amines, phase-separating agents, and additives. Upon absorbing CO2 or being heated, they undergo phase separation, forming lean and rich phases, thereby achieving efficient CO2 enrichment and low-energy regeneration. However, accurately identifying the phase separation initiation point is crucial for understanding the phase separation mechanism and optimizing the absorption process.

[0003] Currently, research on the phase separation process of liquid-liquid two-phase absorbents generally employs an experimental method of introducing CO2 into a bubbling reaction apparatus, allowing it to stand, and then visually observing whether stratification occurs. This method has significant drawbacks: it relies entirely on the experience and judgment of the experimenter, resulting in strong subjectivity and poor reproducibility; it is essentially an "endpoint detection" method, unable to monitor in real-time dynamics, and cannot reflect the dynamic evolution of the phase separation process; it also exhibits low sensitivity and significant hysteresis. Regarding the detection of the dispersed phase, existing instrumental analysis methods have specific limitations when applied to the dynamic phase separation process of liquid-liquid two-phase absorbents, failing to meet the requirements: while optical reflectance methods can identify phase interfaces, their signals are extremely sensitive to dynamically formed and constantly changing phase interfaces, easily generating violent fluctuations and interference, resulting in poor stability and unsuitability for real-time monitoring of the chaotic state at the initial stage of interface formation; electrical property measurement methods lack sufficient sensitivity and cannot respond promptly to the onset of phase separation; transmission turbidimetry is easily affected by incident light intensity drift, residual microbubbles or particulate impurities in the solution, resulting in a low signal-to-noise ratio; spectrophotometry usually requires the addition of specific colorimetric or reactive reagents, which may alter the chemical equilibrium of the system and cause secondary pollution.

[0004] Therefore, there is an urgent need in this field for a method that can objectively, sensitively, in real time, and in situ detect the phase separation initiation point of liquid-liquid two-phase absorbents, in order to overcome subjective observation errors and the shortcomings of existing instrument methods in dynamic and microscopic detection, and to provide a reliable analytical tool for the development and application of two-phase absorbents. Summary of the Invention

[0005] In view of this, the primary objective of the present invention is to overcome the defects of the prior art and provide a method and system for detecting the phase separation point of a two-phase absorbent for capturing CO2, so as to achieve objective, highly sensitive, real-time online detection of the phase separation initiation point of the liquid-liquid two-phase absorbent during CO2 absorption, thereby replacing the subjective judgment that relies on the human eye, and overcoming the problems of low sensitivity, large interference or non-in-situ in dynamic phase separation detection of existing instrument methods.

[0006] The core of this invention lies in establishing the characteristic attenuation of the forward small-angle Mie scattering light signal as a phase split as a detection physical quantity, and constructing a detection system that integrates specific optical path design, signal processing and quantization judgment algorithm, thereby realizing objective, high-sensitivity and real-time online determination of the phase split point.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] In a first aspect, this invention discloses a method for detecting the phase separation point of a two-phase absorbent for capturing CO2. The key lies in irradiating the absorbent solution with a laser of a specific wavelength, collecting its forward small-angle scattered light signal, and analyzing the fluctuation characteristics of the signal intensity in real time, thereby quantitatively determining the phase separation point. Specifically, it includes the following steps:

[0009] S1: Place the two-phase absorbent solution to be tested in a transparent phase-separated reactor and control the reactor temperature at the set value;

[0010] S2: The absorbent solution in the phase-separated reactor is vertically irradiated with a laser light source with a wavelength in the range of 340 nm to 1020 nm;

[0011] S3: Use a linear array CMOS photoelectric sensor to receive the forward scattered light signal generated by the irradiated solution within a scattering angle range of 0.1° to 0.29°;

[0012] S4: Convert the forward-scattered light signal into an electrical signal, and after real-time processing, obtain the sequence I(t) of light intensity changing with time;

[0013] S5: CO2 gas is introduced into the phase-separated reactor for absorption, and the gas absorption and solution settling are alternately cyclical.

[0014] S6: Based on the light intensity sequence I(t), calculate its real-time relative attenuation rate R(t) relative to the initial baseline light intensity I0; monitor whether R(t) is continuously lower than the preset attenuation rate threshold R_th for a preset duration T_hold; when the condition is met, determine that the phase break point has occurred, and record the cumulative CO2 absorption load corresponding to that moment.

[0015] Preferably, step S6 specifically includes:

[0016] (1) Before introducing CO2 gas, the average light intensity of the absorbent solution during the homogeneous stable period is collected and calculated as the initial baseline light intensity I0;

[0017] (2) Set the attenuation rate threshold R_th and the preset duration T_hold;

[0018] (3) During the CO2 absorption process, calculate R(t) = I(t) / I0 in real time;

[0019] (4) When R(t) ≤ R_th, start or accumulate the timing;

[0020] (5) When the cumulative timing time reaches T_hold, the phase break point is determined to have occurred.

[0021] Preferably, the attenuation rate threshold R_th is 5% to 20%. In some embodiments, the attenuation rate threshold R_th is 10%.

[0022] The laser source used in this invention has a wavelength range of 340–1020 nm. This wavelength range highly overlaps with the peak response range of CMOS photoelectric sensors (typically 400–1000 nm), ensuring efficient reception and conversion of scattered light signals, thereby achieving a high signal-to-noise ratio and improving detection sensitivity. Furthermore, this wavelength range covers a variety of mature, low-cost, and stable laser diode models, facilitating system integration and ensuring long-term operational reliability.

[0023] Preferably, the wavelength of the laser source is selected from 650 nm or 980 nm.

[0024] Preferably, the absorbent is a diethylenetriamine (DETA)-sulfolane-water system.

[0025] More preferably, the mass concentration of diethylenetriamine in the absorbent is not less than 1%, and the mass concentration of sulfolane is not less than 5%.

[0026] The core principle of the detection method of this invention is to detect the forward scattered light fluctuations caused by the generation of microdroplets. Therefore, it is applicable in principle to any liquid-liquid system that produces refractive index differences and micron-sized dispersed phases during phase separation. Although some embodiments focus on the DETA-sulfolane-water system, this method can be extended to other amines (such as MEA, MDEA) and phase-separating agents (alcohols, other sulfones) in a simple threshold calibration.

[0027] Secondly, the present invention provides a detection system for implementing the above-described method, the system being designed around high-sensitivity capture of forward-scattered light signals, comprising:

[0028] The optical detection unit includes: a light source module for emitting laser light with wavelengths in the range of 340 nm to 1020 nm; a transparent phase-separated reactor for holding and controlling the temperature of the absorbent solution; and a linear array CMOS sensor for accurately receiving forward-scattered light with a scattering angle of 0.1° to 0.29°.

[0029] The signal processing unit is used to condition, convert analog to digital and acquire the signal output by the sensor;

[0030] The control and analysis unit is configured to execute the aforementioned phase separation point determination algorithm and output the determination result.

[0031] Preferably, the light source module is a semiconductor laser diode with a wavelength of 650 nm or 980 nm.

[0032] Preferably, the linear CMOS sensor integrates 50 to 500 pixels, and the size of a single pixel in its front-end filter array is no greater than 200 μm × 200 μm.

[0033] Preferably, the control and analysis unit is a host computer with dedicated analysis software installed. The software is used to display the light intensity curve in real time, execute the determination algorithm, and record the phase separation point data.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The present invention uses instrument detection and quantification algorithms to completely replace subjective judgment by human eyes, eliminate human error, and the detection results have high repeatability and scientificity.

[0036] (2) Based on the principle of forward small-angle Mie scattering, this invention is extremely sensitive to micron-sized droplets generated in the early stage of phase separation, and can capture early signals before the formation of macroscopic phase interface, thus realizing the precise positioning of the phase separation starting point.

[0037] (3) This invention realizes continuous and dynamic monitoring of the entire process of CO2 absorption-phase separation, and can track the changes in the system state in real time. It is suitable for the evaluation of dynamic processes and process optimization. At the same time, for the diethylenetriamine-sulfolane-water system, the effective detection concentration range of the method is clarified, which improves the reliability and practical guidance value of the method.

[0038] (4) The detection system of the present invention has a compact structure, an integrated design of optical path and signal processing module, and efficient algorithm operation. It can be easily compatible with conventional bubbling absorption devices, has good practicality and application prospects, and helps to promote the standardization and engineering of two-phase absorbent research. Attached Figure Description

[0039] Figure 1 A is a schematic diagram of the overall structure of the detection system of the present invention, and B is a schematic diagram of the forward small-angle scattered light receiving principle in an embodiment of the present invention;

[0040] Figure 2 This is a flowchart of photoelectric signal conversion and preprocessing.

[0041] Figure 3This is a logic block diagram of the phase separation point determination algorithm of the present invention;

[0042] Figure 4 This is a schematic diagram of the light intensity attenuation curve and phase break point determination in Example 1;

[0043] Figure 5 This is a schematic diagram of the light intensity attenuation curve and phase break point determination in Example 1;

[0044] Figure 6 This is a schematic diagram of the light intensity attenuation curve and phase break point determination in Example 1;

[0045] Attached image description: Figure 1 1-Laser source (source module), 2-Incident laser beam, 3-Transparent phase-separating reactor (sample module), 4-Magnetic stirring and heating device, 5-Forward scattered light, 6-Linear array CMOS photoelectric sensor (photoelectric sensing module), 7-Signal processing circuit and data acquisition module (signal processing and acquisition module), 8-Host computer (control and analysis module), 9-CO2 gas inlet pipeline, 10-Temperature sensor, 11-Pressure sensor, 12-Sample solution. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0047] After reading the contents disclosed in this invention, those skilled in the art can make appropriate adjustments or substitutions to the process parameters of the methods and applications described in this invention without departing from the spirit and scope of this invention. Such obvious adjustments, substitutions or combinations should be included within the protection scope of this invention.

[0048] Unless otherwise specified, the materials, reagents, instruments and testing methods used in the following embodiments can be obtained commercially or prepared, operated and implemented with reference to conventional methods disclosed in the art.

[0049] It should be noted that all technical parameters described in this document as numerical ranges (such as temperature, ratio, time, content, etc.) should be understood as encompassing all possible sub-ranges and specific numerical points within that range, regardless of whether the specific numerical value or sub-range is explicitly listed. Unless otherwise specified, the technical terms used in this document have the meanings commonly understood by those skilled in the art.

[0050] Figure 1 A schematic diagram illustrating the structure and principle of the detection system of this invention is shown. Figure 1The phase breakpoint detection system provided by ZhongA is a complete measurement platform integrating optics, electronics, mechanics, and control units. These modules work collaboratively to automate the entire process from signal excitation, acquisition, processing to analysis and judgment. Its specific components are as follows:

[0051] The light source excitation section consists of a laser light source (1) and its driving circuit, specifically a 650 nm or 980 nm semiconductor laser. After collimation, the incident laser beam (2) forms a stable beam that is perpendicularly incident on the sample area.

[0052] Sample reaction and temperature control section: The core is a cylindrical transparent phase-separating reactor (3), made of optical glass or quartz to ensure high light transmittance in the measurement wavelength range. The reactor is placed on a magnetic stirring and heating device (4) to achieve precise temperature control (through an external circulating water bath) and uniform mixing of the solution. The reactor is connected to a CO2 gas inlet pipe (9), a temperature sensor (10), and a pressure sensor (11) to monitor and record the thermodynamic parameters of the absorption process.

[0053] Optical signal acquisition section: This is the key module of the present invention. It consists of a linear array CMOS photoelectric sensor (6) and its front optical components. The sensor is precisely fixed on a multi-dimensional adjustable displacement stage to ensure that it can be accurately aligned with the forward scattered light path from the sample.

[0054] Signal processing and system control section: including signal processing circuit and data acquisition module (7) and host computer (8). After the scattered light signal is converted into an electrical signal by the sensor, it is amplified, filtered and digitized in this module, and then transmitted to the host computer software through the communication interface for real-time display, storage and algorithm analysis.

[0055] The system workflow is as follows: laser irradiates the sample → generates forward scattered light → CMOS sensor receives the optical signal and converts it into an electrical signal → signal processing module performs conditioning and digitization → host computer software displays the light intensity curve in real time and runs the determination algorithm → outputs the phase separation point determination result and the corresponding CO2 load data.

[0056] Figure 1 The principle of the B-type optical design is to select and receive scattered light within a specific angular range of 0.1° to 0.29°, which is the core optical design for achieving high-sensitivity detection.

[0057] Light scattering process: such as Figure 1As shown in Figure B, when the incident laser beam (2) passes through the reactor containing the sample solution (12), the light interacts with the medium. When the system is homogeneous, the light is mainly weakly scattered by the bulk solution; when phase separation begins, a large number of micron-sized droplets are generated in the system. According to the Mie scattering theory, these droplets, which are comparable in size to the laser wavelength, strongly scatter the light, and the intensity distribution of the scattered light has a strong angle dependence.

[0058] Optimized design of the receiving angle: Most of the scattered energy is concentrated within the forward minimum angle. This invention, through precise geometric layout, enables the linear array CMOS sensor (receiver) to receive only forward scattered light with a scattering angle θ in the range of 0.1° to 0.29° (5). This design is based on two optimization considerations: first, maximizing the capture of forward scattered signals to improve the detection sensitivity of microdroplets; second, effectively avoiding extremely strong 0° direct transmitted light to prevent it from saturating or interfering with the sensor, ensuring that the system operates within the optimal range of dynamic range.

[0059] Geometric Implementation: This receiving angle range is achieved by precisely designing and adjusting the distance (D) between the "sample cell center and the receiver sensing surface" and the aperture (d) in front of the receiver, satisfying the following relationship. By mechanically adjusting and locking d and D, the receiving solid angle can be fixed to the desired range of 0.1°-0.29°.

[0060] Figure 2 This paper demonstrates the entire process of converting weak scattered light signals received by a CMOS sensor into clean digital signals suitable for intelligent analysis. This process is fundamental to the high-sensitivity detection achieved in this method and includes the following key steps:

[0061] (1) System Startup and Signal Conditioning (Analog Domain Processing): The process begins with "System Startup". The raw current signal output by the linear CMOS sensor is extremely weak and contains noise. First, it enters the "Signal Conditioning" module for analog filtering and amplification. This stage is accomplished using hardware circuits (such as a transimpedance amplifier with an RC filter network): the microampere-level current signal is amplified to a volt-level voltage signal to adapt to the range of the subsequent ADC. A low-pass filter is used, with the cutoff frequency set much higher than the frequency of the absorption process (such as 100 Hz) to filter out high-frequency circuit noise and ambient light interference, while retaining the low-frequency effective signal reflecting the phase separation process.

[0062] (2) Analog-to-Digital Conversion (ADC): The conditioned analog voltage signal is fed into the "Analog-to-Digital Conversion (ADC)" module. The signal is discretized at a fixed sampling frequency (e.g., 10 Hz) to obtain a discrete digital sequence S[n], where n is the sampling point index. This step converts the continuous physical signal into digital information that can be processed by a microprocessor.

[0063] (3) Digital filtering: To further improve the signal-to-noise ratio, S[n] is subjected to "digital filtering". A digital low-pass filter (such as a Butterworth or Chebyshev filter) implemented in software is usually used, and its cutoff frequency is dynamically set according to the phase (such as 1 Hz). This step outputs a clean signal sequence F[n], which retains the signal variation trend caused by the phase to the maximum extent, while suppressing residual random noise.

[0064] (4) Dynamic threshold calculation: This is the key to the algorithm's adaptability. The system calculates a dynamically changing decision threshold Th[n] in real time. The threshold calculation formula is:

[0065] BG[n] is the estimated mean of the current background signal (i.e. the signal when no phase split occurs), which is updated in real time by moving average; Offset is a fixed offset; K is the sensitivity coefficient (usually taken as 2 to 5). The larger the value of K, the stricter the judgment and the stronger the noise resistance, but the sensitivity will decrease slightly; σ[n] is the noise standard deviation estimate of the current sampling point.

[0066] This dynamic threshold can adapt to slow changes in ambient light or instrument baseline drift, ensuring stability of the determination under different experimental conditions.

[0067] (5) Preliminary event identification: Compare the processed real-time signal F[n] with the dynamic threshold Th[n] ("F[n] > Th[n]?").

[0068] If not, the current data is determined to be background noise, the system outputs a low level, and may use this data to update the background statistics.

[0069] If so, it is initially determined to be a valid event, and a high-level trigger signal is output to indicate that there may be a phase-dependent signal here.

[0070] (6) Post-processing: For the marked "valid events," the post-processing stage begins. This typically includes pulse width timing (measuring the duration of the over-threshold state) and communication reporting (packaging the event information and sending it to the host computer or recording module). The output of this stage is... Figure 3 The input to the advanced decision algorithm is shown.

[0071] Figure 3 This demonstrates the core algorithm logic for automatically and accurately determining the phase break start point based on the preprocessed signal. The algorithm avoids transient interference by monitoring the continuous trend of light intensity attenuation, ensuring the uniqueness and accuracy of the determination.

[0072] (1) Initialization and baseline calibration: After the algorithm starts measuring, it first performs initialization (count = 0, flag = false). count is used to accumulate suspected events, and flag indicates whether the phase point has been determined. Then, it enters the critical baseline light intensity calibration stage: Before introducing CO2 into the system, the system continuously collects N light intensity samples (e.g., N = 300, corresponding to 30 seconds), and calculates their arithmetic mean as the initial average light intensity I0. I0 represents the stable scattered light intensity benchmark of the absorber in a homogeneous, non-CO2-absorbed state.

[0073] (2) Real-time monitoring and attenuation calculation: After the ventilation timer starts at t=0, the system enters the real-time monitoring cycle. At each sampling time t, the current light intensity I(t) is collected, and the relative attenuation rate R(t) = I(t) / I0 is calculated. R(t) directly reflects the degree of light intensity attenuation caused by CO2 absorption and potential phase separation.

[0074] (3) Attenuation threshold judgment and counting: Compare R(t) with the preset attenuation rate threshold R_th (e.g., R_th = 10%) ("R(t) ≤ R_th?").

[0075] If not, it indicates that the attenuation is not significant and has not reached the suspected phase separation standard. The algorithm directly determines the "monitoring termination" condition (such as the total experimental time has expired). If it has not terminated, it returns to the loop start point.

[0076] If so, it indicates a significant decay, and the count of suspected events is incremented (count = count + 1).

[0077] (4) Anti-interference confirmation (continuous trend judgment): After increasing count, immediately judge "count ≥ M?", where M is the anti-interference confirmation threshold (e.g., M = 10). This step requires that the suspected event (R(t) ≤ R_th) must occur continuously or densely M times to be considered as a continuous trend rather than a random fluctuation. If count < M, then continue cyclical monitoring.

[0078] (5) Phase split point determination and recording: When the count reaches M for the first time, the algorithm checks "Is it confirmed for the first time? (flag == false?)".

[0079] If flag is false (first time), then the phase break point data is recorded: the phase break point time t_phase is calculated. Since count records the number of times the condition is continuously met, the actual start time of the phase break should be traced back to the beginning of this continuous trend, i.e., t_phase = t - (M-1) * Δt, where Δt is the sampling interval. Based on the cumulative CO2 absorption corresponding to time t_phase, the CO2 absorption load L_CO2 is calculated. Then, the determined flag (flag = true) is set to ensure that only the first phase break point is recorded throughout the entire experiment.

[0080] If the flag is already true (it has been checked), skip the recording step, only update the display and continue monitoring.

[0081] (6) Loop and Termination: After completing the above steps, determine "Test duration reached?" (or other termination conditions). If not reached, return to the starting point of the real-time monitoring loop and continue to collect data at the next moment; if reached, end the measurement and output the phase break point time t_phase and load L_CO2 and other results.

[0082] Example 1

[0083] Preparation of absorbent: Accurately weigh and prepare 200 mL of absorbent solution consisting of 20 wt% diethylenetriamine (DETA), 40 wt% sulfolane and 40 wt% water.

[0084] Experimental Procedure: The solution was added to the phase-separated reactor, the water bath temperature was set to 40°C, and the magnetic stirrer was turned on (300 rpm). The 650 nm laser source and detection system were started, and after the light intensity curve displayed on the host computer stabilized, baseline data for 300 seconds was recorded. Then, high-purity CO2 (99.99%) was introduced into the reactor at a constant flow rate (50 mL / min) for 5 minutes, followed by shutting off the gas supply and allowing it to stand for 15 minutes to wait for absorption equilibrium. This "gas-suspension" cycle was repeated.

[0085] Results and Judgments: See Figure 4 The system calculates R(t) in real time. During the experiment, the value of R(t) continuously decreased. When it fell below the 10% threshold, the system automatically determined the phase break point at t=148 min (indicated by the arrow), corresponding to a CO2 load of 0.40±0.01 mol / mol (three parallel tests).

[0086] Example 2

[0087] Preparation of absorbent: Prepare 200 mL of a solution containing 30 wt% DETA, 30 wt% sulfolane, and 40 wt% water.

[0088] Experimental procedure: The experiment was conducted at 80°C using a 650 nm laser, following the same steps as in Example 1.

[0089] Results and Judgments: See Figure 5 At higher temperatures, the phase separation process accelerates. The system determined phase separation at t=85 min, corresponding to a load of 0.62±0.02 mol / mol. The results show that the method of the present invention can still work reliably under high-temperature conditions, unaffected by possible enhanced solution convection or slight misting on the vessel walls.

[0090] Example 3

[0091] Preparation of absorbent: Prepare 200 mL of a solution consisting of 10 wt% DETA, 50 wt% sulfolane, and 40 wt% water.

[0092] Experimental procedure: The experiment was conducted at 40°C using a 980 nm near-infrared laser, following the same steps as in Example 1.

[0093] Results and Judgments: See Figure 6 Despite the low concentration of active amine and the weak phase separation signal, the system was still able to clearly capture the abrupt changes in the fluctuation index, determining the phase separation at t=172 min, corresponding to a load of 0.63±0.015 mol CO2 / mol. This demonstrates that the method still has high sensitivity for systems with low amine concentrations and is effective with near-infrared light sources.

[0094] Comparative Example

[0095] This comparative example utilizes visual observation and employs the exact same absorbent, apparatus, and CO2 introduction procedure as Example 1. During the experiment, three experienced researchers independently recorded, through the reactor observation window, the moment they perceived the appearance of a distinct phase interface and their estimated load L. obs1 L obs2 L obs3 .

[0096] Table 1. Results of phase separation point detection in this invention and comparative examples.

[0097]

[0098] As shown in Table 1, the visual observation method suffers from significant subjective differences and systematic lag (by the time macroscopic phase separation is observed, actual phase separation has already been underway for some time), with inter-individual deviations exceeding ±10%. In contrast, the method of this invention yields objective results with high repeatability (standard deviation <3%).

Claims

1. A method for detecting the phase separation point of a two-phase absorbent for capturing CO2, characterized in that, Includes the following steps: S1: Place the two-phase absorbent solution to be tested in a transparent phase-separated reactor and control the reactor temperature at the set value; S2: The absorbent solution in the phase-separated reactor is vertically irradiated with a laser light source with a wavelength in the range of 340 nm to 1020 nm; S3: Use a linear array CMOS photoelectric sensor to receive the forward scattered light signal generated by the irradiated solution within a scattering angle range of 0.1° to 0.29°; S4: Convert the forward-scattered light signal into an electrical signal, and after real-time processing, obtain the sequence I(t) of light intensity changing with time; S5: CO2 gas is introduced into the phase-separated reactor for absorption, and the gas absorption and solution settling are alternately cyclical. S6: Based on the light intensity sequence I(t), calculate its real-time relative attenuation rate R(t) relative to the initial baseline light intensity I0; monitor whether R(t) is continuously lower than the preset attenuation rate threshold R_th for a preset duration T_hold; when the condition is met, determine that the phase break point has occurred, and record the cumulative CO2 absorption load corresponding to that moment.

2. The detection method according to claim 1, characterized in that, Step S6 specifically includes: (1) Before introducing CO2 gas, the average light intensity of the absorbent solution during the homogeneous stable period is collected and calculated as the initial baseline light intensity I0; (2) Set the attenuation rate threshold R_th and the preset duration T_hold; (3) During the CO2 absorption process, calculate R(t) = I(t) / I0 in real time; (4) When R(t) ≤ R_th, start or accumulate the timing; (5) When the cumulative timing time reaches T_hold, the phase break point is determined to have occurred.

3. The detection method according to claim 2, characterized in that, The attenuation rate threshold R_th is between 5% and 20%.

4. The detection method according to claim 1 or 2, characterized in that, The wavelength of the laser source is 650 nm or 980 nm.

5. The detection method according to claim 1, characterized in that, The two-phase absorbent is a diethylenetriamine (DETA)-sulfolane-water system.

6. The detection method according to claim 5, characterized in that, 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. A detection system for implementing the phase separation point detection method according to any one of claims 1 to 6, characterized in that, include: The optical detection unit includes: a light source module for emitting laser light with wavelengths in the range of 340 nm to 1020 nm; a transparent phase-separated reactor for holding and controlling the temperature of the absorbent solution; and a linear array CMOS sensor for accurately receiving forward-scattered light with a scattering angle of 0.1° to 0.29°. The signal processing unit is used to condition, convert analog to digital and acquire the signal output by the sensor; The control and analysis unit is configured to execute the phase separation point determination algorithm as described in claim 1 or 2 and output the determination result.

8. The detection system according to claim 7, characterized in that, The light source module uses a semiconductor laser diode with a wavelength of 650 nm or 980 nm.

9. The detection system according to claim 7, characterized in that, The linear CMOS sensor integrates 50 to 500 pixels, and the size of a single pixel in its front-end filter array is no greater than 200 μm × 200 μm.

10. The detection system according to claim 7, characterized in that, The control and analysis unit is a host computer with dedicated analysis software installed. The software is used to display the light intensity curve in real time, execute the judgment algorithm, and record the phase separation point data.

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