Modularized multi-channel liquid chromatography system based on photoelectric feedback control and intelligent flow regulation method

Abstract

The invention discloses a modularized multi-channel liquid chromatography system based on photoelectric feedback control and an intelligent flow regulation method. The modularized multi-channel liquid chromatography system comprises a chromatographic column and an electric diverter valve assembly, the electric diverter valve assembly comprises a diverter valve controller, a motor, a coupler and a valve body, the motor drives the valve body to open and close through the coupler; a photoelectric switch is arranged close to the coupler; a separation blade is arranged on the motor rotating shaft; two branch pipelines are arranged on the valve body; the tail end of each branch pipeline is connected with a detector; a pressure regulating valve and a pressure sensor are arranged on one branch pipeline; one end of the chromatographic column is connected with the pump, and the other end of the chromatographic column is connected with the valve body through a main pipeline; and the diverter valve controller is connected with the photoelectric switch, the motor and the pressure regulating valve. The technical problem that a traditional liquid chromatography system only supports fixed-proportion shunting and cannot dynamically adjust the shunting amount to meet the real-time requirements of double detectors is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of analytical chemical instruments, and in particular relates to a modular multi-channel liquid chromatography system based on photoelectric feedback control and an intelligent flow regulation method. Background Art

[0002] Liquid chromatography (HPLC) is an analytical technique commonly used to separate and quantitatively analyze chemical components in solutions. Traditionally, ultraviolet detectors (UV) are widely used to detect ultraviolet absorbing substances in samples. However, when faced with some substances with no or weak ultraviolet absorption, or when the maximum wavelength of ultraviolet absorption overlaps with commonly used mobile phases (such as methanol, acetonitrile, etc.), the performance of the UV detector will drop significantly. To solve this problem, researchers began to add an evaporative light detector (ELSD) as a supplementary detector based on the UV detector. In liquid chromatography, the flow rate of the mobile phase usually flows to the UV detector at tens of milliliters per minute, while the ELSD only requires a flow rate of tens of microliters. There is a big difference in the flow requirements of the two. Therefore, how to effectively distribute the sample flow to the UV detector and the ELSD detector at the same time and ensure the stable operation of the system is a key technical problem in the liquid chromatography system. Summary of the Invention

[0003] The present invention provides a modular multi-channel liquid chromatography system and an intelligent flow regulation method based on photoelectric feedback control, which aims to solve the technical problem that traditional liquid chromatography systems only support fixed-ratio diversion in existing diversion devices and cannot dynamically adjust the diversion flow to match the real-time requirements of dual detectors.

[0004] A modular multi-channel liquid chromatography system based on photoelectric feedback control includes a chromatography column and an electric diverter valve assembly; the electric diverter valve assembly includes a motor, a coupling, a valve body, and a diverter valve controller connected in sequence; the motor drives the valve body to open and close via the coupling; a photoelectric switch is installed near the coupling; a baffle is provided on the motor shaft; the baffle is used to block or allow light to pass through the photoelectric switch to determine whether the valve is reset; two branch pipelines are provided on the valve body; a detector is connected to the end of each branch pipeline; a pressure regulating valve and a pressure sensor are provided on one branch pipeline;

[0005] One end of the chromatographic column is connected to the pump, and the other end of the chromatographic column is connected to the valve body through the main pipeline. The mobile phase separated by the chromatographic column is transported to each detector through the main pipeline and the valve body; the diverter valve controller is connected to the photoelectric switch, the motor and the pressure regulating valve to dynamically adjust the valve opening of the motor-driven valve body and the branch back pressure in the corresponding branch pipeline.

[0006] Preferably, the pump, pressure sensor and diverter valve controller are connected to the host respectively, and the host sets the instruction main flow Q 主 The pressure sensor feeds back the pressure signal to the host in real time, and the host then distributes it to the diverter valve controller.

[0007] Preferably, the photoelectric switch is a beam-type photoelectric switch, comprising a transmitter and a receiver, and generating an electrical signal by opening and closing the optical path between the transmitter and the receiver; the baffle is a metal sheet or plastic sheet fixed on the motor shaft, and the baffle moves synchronously with the movement of the motor shaft, blocking or allowing the light emitted by the transmitter to reach the receiver.

[0008] Preferably, the motor, valve body and photoelectric switch are all fixedly mounted on a mounting base.

[0009] Preferably, a sleeve is provided at the connection between the coupling and the valve stem of the valve body; the gap between the inner wall of the sleeve and the valve stem is ≤5 μm; two annular grooves are provided axially on the inner wall of the sleeve; a chemical corrosion-resistant annular ring is pressed into the annular groove, and the annular ring forms an interference fit with the valve stem surface of the valve body.

[0010] Preferably, the chromatographic column is connected to the pump via a high-pressure pipeline; the joints between the high-pressure pipeline, the pump and the chromatographic column are sealed without leakage.

[0011] Preferably, the coupling is an elastic coupling, and the axial compensation amount of the coupling is ≥0.2 mm.

[0012] This intelligent flow regulation method for a modular multi-channel liquid chromatography system based on photoelectric feedback control is characterized by comprising the following steps.

[0013] Step 1: System initialization and parameter setting: Parameters include main flow rate Q 主 , flow ratio of each branch, pressure threshold P max , initialize the pressure regulating valve.

[0014] Step 2: Photoelectric feedback system calibration: including calibration of the synchronization between the baffle and the motor shaft and calibration of the photoelectric switch signal.

[0015] Step 3: Closed-loop control logic verification: including dynamic response testing and abnormal state simulation.

[0016] Step 4: Coordinated control of flow and pressure during system operation. The specific control methods are as follows:

[0017] When the main flow rate Q 主 When the change is greater than 5%, adjust the valve opening in advance;

[0018] When the main flow rate Q 主 When the change is ≤5%, establish the pressure regulation priority level:

[0019] If the pressure deviation of any branch pipeline is greater than 10%, the pump power supply will be cut off immediately, the pressure regulating valve will be opened and an alarm will be sounded;

[0020] When the pressure deviation of the branch pipeline is between 5% and 10%, the opening of the pressure regulating valve on the corresponding branch pipeline should be adjusted first to return the pressure to the set value;

[0021] When the pressure deviation of any branch pipeline is less than 5%, the host sends instructions to the diverter valve controller according to the preset flow ratio; at the same time, the diverter valve controller dynamically adjusts the motor speed through the PID algorithm to control the valve opening to achieve flow distribution.

[0022] Step 5: Data closed-loop verification and traffic prediction value optimization.

[0023] Preferably, the specific method for calibrating the synchronization between the baffle and the motor shaft in step 2 is: calibrating the position of the motor shaft using a micrometer, rotating the shaft to 0°, 90°, and 180°, and recording the change in the photoelectric switch signal;

[0024] The specific method of photoelectric switch signal calibration is: within the full range of valve travel, record the photoelectric switch signal intensity with a step length of 10% of the opening, draw a signal-opening curve, and require the linearity error to be less than 1%.

[0025] Preferably, the dynamic response test in the closed-loop control logic verification of step 3 is: the time from the issuance of the command to the valve being in place is less than 50ms, and the flow rate change slope meets the expected value;

[0026] The abnormal state simulation is as follows: disconnecting the power supply of the photoelectric switch to verify whether the system can trigger the fault protection and switch to the backup control mode within the designed time;

[0027] The mechanical sticking test involves applying resistance to the valve stem to check whether the motor torque protection function is working properly.

[0028] Compared with the prior art, the present invention has the following beneficial effects.

[0029] 1. The system of the present invention can adjust the pump flow and diversion ratio in real time through the host automatic control, which simplifies the operation steps, improves the automation level of the system, and reduces manual intervention; at the same time, the automatic diversion valve assembly realizes the precise distribution of micro-liter flow through high-precision motor drive and feedback control, and cooperates with the pressure regulating valve to suppress interference. The collaboration between the two depends on real-time data interaction (flow, pressure, valve opening) and intelligent algorithms (PID), which ultimately solves the synchronization and accuracy problems when high and low flow detectors are connected in parallel. The valve body is based on the Q provided by the host. 主 And valve upstream pressure P 前, adjusting the valve opening θ in real time to ensure that the flow in each branch pipeline is accurate to the set value (such as 50μL / min). The pressure regulating valve is located at the rear end of the branch pipeline and offsets pump pulsation or column pressure fluctuations by adjusting the back pressure to prevent the diversion ratio from drifting.

[0030] 2. The block multi-channel liquid chromatography system and intelligent flow regulation method of the present invention utilize valve control flow distribution and combine different detection technologies (UV and ELSD detection technology) to achieve accurate analysis of multiple substances. While improving the accuracy of liquid chromatography detection, the system solves the challenges brought by the difference in flow demand, enables the sample to reach the UV detector and ELSD detector at the same time, and solves the problem of the difference in flow demand between the two while ensuring the accuracy of analysis. It has high technical innovation and broad application prospects.

[0031] The present invention will be further described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the electric diverter valve assembly in the present invention.

[0033] Figure 2 Schematic diagram of the structure of the modular multi-channel liquid chromatography system of the present invention.

[0034] Figure 3 This is a control flow chart of the modular multi-channel liquid chromatography system of the present invention.

[0035] 1 - Motor, 2 - Photoelectric switch, 3 - Baffle, 4 - Coupling, 5 - Sleeve, 6 - Valve body, 7 - Mounting seat, 8 - Main pipeline, 9 - Branch pipeline, 10 - Pump, 11 - Pressure sensor, 12 - Chromatographic column, 13 - Detector, 15 - Pressure regulating valve, 16 - Main unit, 17 - High-pressure pipeline. DETAILED DESCRIPTION

[0036] like Figure 1-3As shown, this modular multi-channel liquid chromatography system based on photoelectric feedback control includes a chromatographic column 12 and an electric diverter valve assembly; the electric diverter valve assembly includes a motor 1, a coupling 4, a valve body 6 and a diverter valve controller connected in sequence; the inner wall of the valve body 6 is coated with DLC, and the surface roughness Ra ≤ 0.1 μm; the motor 1 drives the valve body 6 to open and close through the coupling 4; a photoelectric switch 2 is installed near the coupling 4; a baffle 3 is provided on the rotating shaft of the motor 1, which moves synchronously with the rotating shaft of the motor 1; the baffle 3 is used to block or allow light to pass through the photoelectric switch, and judge Whether the valve is reset (closed); motor 1 serves as an actuator, receives the driving signal (such as step pulse, PWM wave) of the diverter valve controller, drives the valve stem to move through the coupling 4, and directly controls the valve opening; the diverter valve controller serves as the control core, and generates a motor driving instruction according to the difference between the target opening and the actual opening feedback from the photoelectric switch to form a closed-loop control; the control process of the diverter valve controller is: target opening setting → diverter valve controller calculates the motor driving amount → motor rotation → valve stem displacement → photoelectric switch detects the actual opening → feedback to the diverter valve controller → corrects the driving amount until the error approaches zero.

[0037] Two branch lines 9 are provided on the valve body 6; a detector 13 is connected to the end of each branch line 9; and a pressure regulating valve 15 and a pressure sensor 11 are provided on one branch line 9. In this embodiment, one branch line 9 is a UV liquid inlet line, and the detector 13 provided at the end of the UV liquid inlet line is a UV detector. The other branch line 9 is an ELSD liquid inlet line, and the detector 13 provided at the end of the ELSD liquid inlet line is an ELSD detector. The pressure regulating valve 15 is provided on the UV liquid inlet line near the UV detector. The pressure sensor 11 is provided on the UV liquid inlet line, near the outlet of the valve body 6, with a sampling frequency of ≥10 Hz to ensure dynamic response. The pressure sensor 11 monitors the outlet pressure of the valve body 6 in real time.

[0038] One end of the chromatographic column 12 is connected to the pump 10, and the other end of the chromatographic column 12 is connected to the inlet end of the valve body 6 through the main pipeline 8. The mobile phase separated by the chromatographic column 12 is transported to each detector 13 through the main pipeline 8 and the valve body 6; the diverter valve controller is respectively connected to the photoelectric switch 2, the motor 1 and the pressure regulating valve 15, and dynamically adjusts the valve opening of the valve body 6 driven by the motor 1 and the branch back pressure in the corresponding branch pipeline 9. The pump 10 is connected to the host 16 through a communication interface (such as RS-232 or Ethernet), and the host 16 sets the instruction main flow Q 主 , and sent to the pump 10, thereby controlling the working state of the pump 10; the pressure sensor 11 diverter valve controller is also connected to the host 16, and the host 16 sets the instruction main flow Q 主At the same time, the pressure sensor 11 feeds back the real-time pressure signal to the host 16, which is then distributed to the diverter valve controller by the host 16.

[0039] The host 16 is based on the valve front pressure P 前 Dynamically adjust the speed or stroke of the pump 10 to maintain the system pressure stable. The diverter valve controller is based on the real-time data of the pressure sensor feedback provided by the host 16, combined with the UV demand flow Q UV , calculate the valve opening θ and flow distribution; if the flow fluctuation of the pump 10 exceeds the threshold, the diverter valve controller triggers the diverter valve dynamic compensation and adjusts the back pressure of the pressure regulating valve 15 at the same time.

[0040] In this embodiment, the photoelectric switch 2 is a through-beam photoelectric switch, comprising a transmitter and a receiver. It generates an electrical signal by opening and closing the optical path between the transmitter (infrared LED) and the receiver (phototransistor). The baffle 3 is a metal or plastic sheet fixed to the rotating shaft of the motor 1. It moves synchronously with the movement of the motor 1, blocking or allowing light from the transmitter to reach the receiver. The initial position of the baffle 3 corresponds to the fully closed valve state (0% opening); the range of movement of the baffle 3 must cover the full valve opening stroke (e.g., 0 to 10 mm).

[0041] Of course, in other embodiments, the photoelectric switch 2 can also be a reflective switch. The working principle of a reflective switch is to detect the presence of an object by emitting light and receiving light reflected from the object's surface. This type of sensor is generally composed of a light source (such as an LED) and a light receiver (such as a photodiode or phototransistor). The baffle 3 can block or reflect light. When the baffle 3 approaches or passes through the reflective switch, its behavior affects the reflection of light, thereby triggering a response from the sensor.

[0042] In this embodiment, the motor 1, valve body 6 and photoelectric switch 2 are all fixedly mounted on the mounting base 7; the mounting base 7 is used to fix various components of the liquid chromatography system to ensure the stability of the equipment and the convenience of operation.

[0043] In this embodiment, a sleeve 5 is positioned at the connection between the coupling 4 and the valve stem of the valve body 6. Sleeve 5 utilizes a multi-layer titanium alloy bellows structure, boasting an axial stiffness of >500 N / mm and a radial flexibility of 0.1 mm / N, achieving vibration attenuation exceeding 40 dB. A clearance of ≤5 μm is maintained between the inner wall of sleeve 5 and the valve stem. Two annular grooves are axially defined on the inner wall of sleeve 5, with a spacing typically 5 to 10 mm, designed to meet sealing requirements. A chemically corrosion-resistant annular ring, made of fluororubber or perfluoroether, is pressed into the grooves, forming an interference fit with the surface of the valve stem of the valve body 6. The compression ratio of the annular ring is approximately 15% to 30%. The first seal (upstream): The annular ring near the fluid side primarily prevents axial leakage of high-pressure mobile phases (such as methanol and acetonitrile) along the valve stem. The second seal (downstream): The annular ring near the motor 1 side serves as a redundant barrier, preventing small amounts of leaking liquid from entering the coupling 4 or motor 1. When the valve stem moves linearly, the annular ring maintains contact pressure with the valve stem through elastic deformation. Even if there are micron-level scratches or wear on the valve stem surface, it can still maintain sealing, providing a dynamic seal compensation mechanism. Sleeve 5 has three threaded holes, and countersunk screws are used to fix sleeve 5 to the valve stem and ensure a certain degree of coaxiality.

[0044] In this embodiment, the chromatographic column 12 is connected to the pump 10 via a high-pressure pipeline 17 ; the high-pressure pipeline 17 has a high-pressure tolerance of ≥40 MPa, and the joints between the high-pressure pipeline 17 and the pump 10 and the chromatographic column 12 are sealed without leakage.

[0045] In this embodiment, the coupling 4 is an elastic coupling with an axial compensation of ≥0.2 mm. If there is a slight deviation between the motor 1 and the valve body 6 (such as axial offset caused by thermal expansion), the flexible structure of the coupling 4 can be adaptively adjusted to avoid additional stress on the bearing.

[0046] In this embodiment, the diverter valve controller is usually fixed on the mounting base 7 or on an adjacent rack, and is connected to the motor 1 and the photoelectric switch 2 via a short cable to reduce signal delay.

[0047] In this embodiment, the working principle of each component is as follows: the pump 10 serves as the mobile phase driving force source of the system, is located at the front end of the chromatographic column 12, is connected to the inlet of the chromatographic column 12 through the high-pressure pipeline 17, and works in conjunction with the valve body 6, the pressure regulating valve 15) and the main unit 16. Its core function is to provide a stable flow and pressure basis for the diverter valve, and to achieve precise diversion and synchronous analysis of high and low flow detectors through real-time data interaction. The pump 10 maintains a stable main flow (such as 30mL / min) and pre-valve pressure (such as 8MPa).

[0048] The diverter valve controller works in conjunction with the photoelectric switch 2 to determine the valve opening by monitoring the position of the valve body 6 in real time. The photoelectric switch 2 is installed near the coupling 4 to detect its movement. The baffle 3 follows the movement of the motor 1's shaft, blocking or allowing light to pass through the photoelectric switch 2. This feedback provides the diverter valve controller with valve position information, which then controls the opening and closing of the valve body 6. Based on the valve body 6 position data fed back by the photoelectric switch 2, the diverter valve controller controls the motor 1 to drive the coupling 4, which in turn drives the valve body 6 to open and close. The motor 1, through the coupling 4, drives the valve to regulate flow and backpressure.

[0049] The diverter valve controller adjusts the flow distribution of the branch pipeline 9 on the valve body 6 according to the needs of the system. The valve body 6 selects different branch pipelines under the control of the diverter valve controller, thereby adjusting the flow direction or flow of the mobile phase.

[0050] Pressure regulating valves 15 are provided in some branch lines 9 to adjust the pressure of the fluid. By adjusting the back pressure (e.g., 2 MPa), pump pulsation or column pressure fluctuations are offset to prevent diversion ratio drift.

[0051] Pressure sensor 11 monitors the real-time pressure of branch line 9. This real-time data is fed back to host computer 16, which analyzes it and transmits instructions to the diverter valve controller to adjust the opening of the valve driven by motor 1, thereby dynamically adjusting the flow rate and pressure to ensure stable operation of the liquid chromatography system.

[0052] In this embodiment, the baffle 3 is wedge-shaped or V-shaped, and the nonlinear profile design makes the output signal of the photoelectric switch and the valve opening have a linear relationship.

[0053] The system of this embodiment is also provided with a fault response mechanism, which includes overvoltage protection and flow abnormality processing;

[0054] Overpressure protection: If the pressure before the valve P 前 When the pressure exceeds the threshold (such as 40MPa), the pump automatically slows down or stops, and the diverter valve closes.

[0055] Flow abnormality processing: When UV demand flow Q UV When the deviation is greater than 5%, the system self-check is triggered and the valve opening is recalibrated or blocked.

[0056] In this embodiment, coupling 4 connects the motor shaft to the valve stem of valve body 6. The coupling 4 and the valve stem are connected by a mechanism (e.g., threaded drive, gears, etc.) to convert the motor's rotational motion into linear motion of the valve stem. Coupling 4 can be a rigid coupling (e.g., a flange coupling) that requires strict alignment and is suitable for high-precision applications, or a flexible coupling (e.g., a plum blossom coupling) that allows for some deviation and absorbs vibration and is suitable for general industrial applications.

[0057] This intelligent flow regulation method for a modular multi-channel liquid chromatography system based on photoelectric feedback control is characterized by:

[0058] Step 1: System initialization and parameter setting, including: detecting the alignment of the transmitter and receiver optical paths of the photoelectric switch 2 and the initial signal stability (fluctuation <1%); confirming the initial position of the motor 1 (fully closed / fully open), and verifying the initial signal state by blocking the photoelectric switch 2 with the baffle 3; initializing the pressure regulating valve 15 (the pressure regulating valve 15 sets the initial opening based on the pipeline characteristic curve, such as fully open or 30%-50% opening according to the preset pressure); checking the sealing of the high-pressure pipeline 17 (helium mass spectrometer leak rate <1×10 -7 Pa·m 3 / s) and input setting parameters to the host 16; Design parameters include main flow Q 主 , flow ratio of each branch (such as Q1:Q2), pressure threshold P max .

[0059] Step 2: Photoelectric feedback system calibration: including calibration of the synchronization between the baffle 3 and the shaft of the motor 1 and calibration of the signal of the photoelectric switch 2;

[0060] The specific method for calibrating the synchronization between the baffle 3 and the shaft of the motor 1 is as follows: use a micrometer ruler (resolution ≤ 0.01mm) to calibrate the shaft position of the motor 1, rotate the shaft to 0°, 90°, and 180°, and record the signal changes of the photoelectric switch 2; requirements: the corresponding error between the valve stem angle and the photoelectric switch signal is ≤ 0.05°, and the displacement repeatability error of the baffle 3 is < ±0.1°.

[0061] The specific method for calibrating the signal of photoelectric switch 2 is the signal stability test: within the full stroke range of the valve (0-100% opening), record the photoelectric switch signal intensity (such as voltage value) in steps of 10% of the opening, and draw a signal-opening curve. The linearity error is required to be less than 1% (if nonlinear, a software compensation algorithm needs to be introduced).

[0062] Step 3: Closed-loop control logic verification: including dynamic response testing and abnormal state simulation;

[0063] Dynamic response test: the time from the command to the valve is less than 50ms, and the flow rate change slope meets the expected value (such as linearity R 2 >0.99, R 2 It is a commonly used statistic in regression analysis and is usually used to measure the linear fit of data in regression analysis);

[0064] The abnormal state simulation is as follows: disconnecting the power supply of photoelectric switch 2 to verify whether the system can trigger fault protection within 100ms and switch to the backup control mode.

[0065] The mechanical sticking test is to apply 5N resistance to the valve stem to check whether the torque protection function of motor 1 is working properly.

[0066] Step 4: Coordinated control of flow and pressure during system operation. The specific control methods are as follows:

[0067] When the main flow rate Q 主 When the change is greater than 5%, adjust the opening of the valve body 6 in advance;

[0068] When the main flow rate Q 主 When the change is ≤5%, establish the pressure regulation priority level:

[0069] If the pressure deviation of any branch pipeline 9 is greater than 10%, the power supply of the pump 10 will be immediately cut off, and the pressure regulating valve 15 will be opened and an alarm will be issued;

[0070] When the pressure deviation of the branch line 9 is between 5% and 10%, the opening of the pressure regulating valve 15 on the corresponding branch line 9 is adjusted first to return the pressure to the set value; among them, pressure regulation takes priority over flow distribution to avoid flow drift caused by pressure fluctuations.

[0071] When the pressure deviation of any branch pipeline 9 is less than 5%, the host 16 sends a command to the diverter valve controller according to the preset flow ratio (e.g., Q1:Q2=3:2); at the same time, the diverter valve controller dynamically adjusts the speed of the motor 1 through the PID algorithm to control the valve opening to achieve flow distribution;

[0072] In step 4, the method for the diverter valve controller to dynamically adjust the speed of motor 1 through the PID algorithm is as follows: a PID (proportional-integral-differential) control algorithm is introduced into the diverter valve controller to further optimize the adjustment of the valve opening and back pressure; at this time, the PID control algorithm will achieve precise control of the target flow and pressure by continuously adjusting the valve opening.

[0073] Step 5: Data closed-loop verification and self-optimization, as follows:

[0074] Flow distribution accuracy verification: After each adjustment is completed, the accuracy is verified by integrating the flow;

[0075] Verification of relative standard deviation (RSD): SPC control chart was used to analyze long-term flow data and outliers were removed. SPC control chart was used to analyze long-term flow data and RSD was less than 1.2% after removing outliers.

[0076] The calculation formula is:

[0077] The optimization of flow prediction values is specifically as follows: applying machine learning to optimize flow prediction, using an offline training nonlinear model, with the input parameters being pump speed, valve opening, and pressure, and the output being the flow prediction value; using 80% training data and 20% test data, the flow prediction error is <3%.

[0078] The above embodiments are not exhaustive of specific implementation methods, and there may be other embodiments. The above embodiments are intended to illustrate the present invention rather than to limit the scope of protection of the present invention. All applications derived from simple variations of the present invention fall within the scope of protection of the present invention.

Claims

1. A modular multi-channel liquid chromatography system based on photoelectric feedback control, characterized in that: The invention comprises a chromatographic column (12) and an electric diverter valve assembly; the electric diverter valve assembly comprises a motor (1), a coupling (4), a valve body (6) and a diverter valve controller connected in sequence; the motor (1) drives the valve body (6) to open and close via the coupling (4); a photoelectric switch (2) is installed near the coupling (4); a baffle (3) is provided on the rotating shaft of the motor (1); the baffle (3) is used to block or allow light to pass through the photoelectric switch (2) to determine whether the valve is reset; two branch pipes (9) are provided on the valve body (6); a detector (13) is connected to the end of each branch pipe (9); a pressure regulating valve (15) and a pressure sensor (11) are provided on one branch pipe (9); One end of the chromatographic column (12) is connected to the pump (10), and the other end of the chromatographic column (12) is connected to the valve body (6) through the main pipeline (8). The mobile phase separated by the chromatographic column (12) is transported to each detector (13) through the main pipeline (8) and the valve body (6); the diverter valve controller is connected to the photoelectric switch (2), the motor (1) and the pressure regulating valve (15), and dynamically adjusts the valve opening of the valve body (6) driven by the motor (1) and the branch back pressure in the corresponding branch pipeline (9).

2. The modular multi-channel liquid chromatography system based on photoelectric feedback control according to claim 1, characterized in that: The pump (10), pressure sensor (11) and diverter valve controller are respectively connected to a host (16), and the host (16) sets the instruction main flow Q 主 The pressure sensor (11) feeds back the pressure signal to the host (16) in real time, and the host (16) distributes the pressure signal to the diverter valve controller.

3. The modular multi-channel liquid chromatography system based on photoelectric feedback control according to claim 1, characterized in that: The photoelectric switch (2) is a beam-type photoelectric switch, comprising a transmitter and a receiver, and generates an electrical signal by opening and closing the optical path between the transmitter and the receiver; the baffle (3) is a metal sheet or a plastic sheet fixed on the rotating shaft of the motor (1), and the baffle (3) moves synchronously with the movement of the rotating shaft of the motor (1), thereby blocking or allowing the light emitted by the transmitter to reach the receiver.

4. The modular multi-channel liquid chromatography system based on photoelectric feedback control according to claim 1, characterized in that: The motor (1), valve body (6) and photoelectric switch (2) are all fixedly mounted on a mounting base (7).

5. The modular multi-channel liquid chromatography system based on photoelectric feedback control according to claim 1, characterized in that: A sleeve (5) is sleeved at the connection between the coupling (4) and the valve stem of the valve body (6); a gap between the inner wall of the sleeve (5) and the valve stem is ≤5μm; two annular grooves are axially arranged on the inner wall of the sleeve (5); a chemical corrosion-resistant annular ring is pressed into the annular groove, and the annular ring forms an interference fit with the valve stem surface of the valve body (6).

6. The modular multi-channel liquid chromatography system based on photoelectric feedback control according to claim 1, characterized in that: The chromatographic column (12) is connected to the pump (10) via a high-pressure pipeline (17); the joints between the high-pressure pipeline (17), the pump (10) and the chromatographic column (12) are sealed without leakage.

7. The modular multi-channel liquid chromatography system based on photoelectric feedback control according to claim 1, characterized in that: The coupling (4) is an elastic coupling, and the axial compensation amount of the coupling (4) is ≥0.2 mm.

8. An intelligent flow regulation method for a modular multi-channel liquid chromatography system based on photoelectric feedback control according to any one of claims 1 to 7, characterized in that: Step 1: System initialization and parameter setting: Parameters include main flow rate Q 主 , flow ratio of each branch, pressure threshold P max , initializing the pressure regulating valve (15); Step 2: Calibration of the photoelectric feedback system: including calibration of the synchronization between the baffle (3) and the rotating shaft of the motor (1) and calibration of the signal of the photoelectric switch (2); Step 3: Closed-loop control logic verification: including dynamic response testing and abnormal state simulation; Step 4: Coordinated control of flow and pressure during system operation. The specific control methods are as follows: When the main flow rate Q 主 When the change is greater than 5%, the opening of the valve body (6) is adjusted in advance; When the main flow rate Q 主 When the change is ≤5%, establish the pressure regulation priority level: If the pressure deviation of any branch pipeline (9) is greater than 10%, the power supply of the pump (10) is immediately cut off, the pressure regulating valve (15) is opened and an alarm is sounded; When the pressure deviation of the branch pipeline (9) is between 5% and 10%, the opening of the pressure regulating valve (15) on the corresponding branch pipeline (9) is preferentially adjusted to return the pressure to the set value; When the pressure deviation of any branch pipeline (9) is less than 5%, the host (16) sends a command to the diverter valve controller according to the preset flow ratio; at the same time, the diverter valve controller dynamically adjusts the speed of the motor (1) through the PID algorithm to control the valve opening to achieve flow distribution; Step 5: Data closed-loop verification and traffic prediction value optimization.

9. The intelligent flow rate regulation method for a modular multi-channel liquid chromatography system based on photoelectric feedback control according to claim 8, characterized in that: The specific method for calibrating the synchronization between the baffle (3) and the rotating shaft of the motor (1) in step 2 is as follows: using a micrometer to calibrate the rotating shaft position of the motor (1), rotating the rotating shaft of the motor (1) to 0°, 90°, and 180°, and recording the signal change of the photoelectric switch (2); The specific method of photoelectric switch (2) signal calibration is: within the full range of valve travel, record the photoelectric switch signal intensity with 10% of the opening as a step, draw a signal-opening curve, and require the linearity error to be less than 1%.

10. The intelligent flow rate regulation method for a modular multi-channel liquid chromatography system based on photoelectric feedback control according to claim 8, characterized in that: The dynamic response test in the closed-loop control logic verification of step 3 is as follows: the time from the issuance of the command to the valve being in place is less than 50ms, and the flow rate change slope meets the expected value; The abnormal state simulation is as follows: disconnecting the power supply of the photoelectric switch (2) to verify whether the system can trigger the fault protection and switch to the backup control mode within the designed time; The mechanical sticking test is to apply resistance to the valve stem to check whether the torque protection function of the motor (1) is working properly.

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