A method and system for automatic control of liquid level in a multiphase continuous flow reactor

Abstract

This application relates to an automatic liquid level control method and system for a multiphase continuous flow reactor, applicable to scenarios where the gas phase and liquid phase flow continuously simultaneously without the need for a liquid level sensor. The method includes: acquiring the equivalent gas inlet flow rate, reactor temperature, and gas phase outlet pressure; when preset identification conditions are met, controlling the electronic pressure controller on the gas outlet side to briefly close within a preset acquisition time, acquiring a first pressure value and a second pressure value during the closure process, and calculating the pressure change; based on the acquisition time, the equivalent gas inlet flow rate, temperature, and pressure change, calculating the equivalent gas phase volume between the reactor liquid surface and the gas phase outlet according to the gas state relationship, and establishing a reference volume using the initial identification result; periodically calculating the current equivalent gas phase volume in the operation control cycle, comparing it with the reference volume to obtain the deviation, and adjusting the liquid pump flow rate when the deviation exceeds a threshold to bring the equivalent gas phase volume back to the allowable fluctuation range, thereby achieving automatic liquid level stabilization.

Description

Technical Field

[0001] This application relates to the field of chemical reactor control technology, and in particular to an automatic liquid level control method and system for a multiphase continuous flow reactor. Background Technology

[0002] In continuous flow reaction systems, especially in reaction processes involving gaseous, liquid, and solid phase feedstocks, the presence of solid particles in the system and their dynamic changes in deposition state with reaction conditions lead to continuous fluctuations in the liquid reflux rate, making it difficult to maintain a stable reactor liquid level.

[0003] Traditional control methods rely on manual real-time monitoring or direct measurement using liquid level sensors to adjust the liquid pump flow rate and achieve stable liquid levels. However, in special operating conditions where the reactor is exposed to external light, magnetic fields, etc., the physical presence of liquid level sensors can interfere with the reaction environment or prevent their installation, leading to control failure. Furthermore, the simultaneous flow of gas and liquid phases in multiphase continuous flow processes makes it impossible to reliably obtain liquid level height using conventional sensors, further complicating automatic control.

[0004] With the increasing demand for industrial automation, there is an urgent need for an automatic control mechanism that does not rely on direct measurement of liquid level by liquid level sensors, but indirectly calculates the liquid level state based solely on gas phase flow parameters, in order to solve the technical bottleneck of liquid level stability in special scenarios. Summary of the Invention

[0005] The purpose of this application is to provide an automatic liquid level control method and system for a multiphase continuous flow reactor, which solves the problem that liquid level sensors cannot be installed or interfere with the reaction environment under special operating conditions, and realizes automatic liquid level stability control without relying on direct measurement.

[0006] The proposed solution is as follows:

[0007] According to a first aspect of the embodiments of this application, an automatic liquid level control method for a multiphase continuous flow reactor is provided, applicable to scenarios where the gas phase and liquid phase are simultaneously in continuous flow and the liquid level height is not directly measured using a liquid level sensor, comprising: S1. Obtain the equivalent flow rate of gas inlet, the temperature inside the reactor, and the pressure information at the gas outlet. S2. When the preset identification conditions are met, the electronic pressure controller on the gas outlet side is closed within the preset acquisition time t, causing a pressure change in the gas phase space inside the reactor. The first pressure value P1 is acquired at the first preset moment after the closing action begins, and the second pressure value P2 is acquired at the second preset moment before the preset acquisition time t ends and the reactor is reopened. The pressure change ΔP within the preset acquisition time t is calculated based on the first pressure value P1 and the second pressure value P2. S3. Based on the preset acquisition time t, the equivalent gas inlet flow rate A, the temperature T and pressure change ΔP inside the reactor, calculate the equivalent gas volume V between the reactor liquid surface and the gas phase outlet under actual operating conditions according to the gas state relation equation. g ; S4. Use the equivalent gas volume obtained from the initial identification under the target state as the reference volume V. g0 ; S5. Enter the operation control loop, periodically execute steps S2 to S3 to obtain the gas phase equivalent volume V for the current period n. gn Calculate V gn With V g0 The deviation between the two is monitored, and the liquid pump flow rate is adjusted when the deviation exceeds a preset deviation threshold, so that V gn Back to V g0 Within the corresponding allowable fluctuation range, the liquid level can be automatically stabilized.

[0008] Preferably, the identification conditions include: The liquid level in the reactor remains stable for a preset duration, and turning off the electronic pressure controller within a preset sampling duration t will not affect the continuity of the reaction process.

[0009] Preferably, the equivalent gas volume V between the reactor liquid surface and the gas phase outlet under actual operating conditions is calculated according to the gas state equation. g ,include: Calculate the equivalent volume of gas entering the reactor within the preset data acquisition time t under actual operating conditions: ΔV=At; Where A represents the equivalent gas intake flow rate under actual operating conditions; Calculate the pressure change ΔP within the data acquisition time t: ΔP = P2 - P1; When the system is in a relatively steady state, ΔP = f(ΔV, T1, P1); Wherein, T1 represents the actual operating temperature at the first preset time; In the ideal gas state, ΔP = P1ΔV / V g Then V g =P1ΔV / ΔP; In a non-ideal gas state, P2T1 / P1T2=Z2(V g +ΔV) / Z1V g Then V g =ΔV×Z2P1T2 / (Z1P2T1-Z2P1T2); Where Z1 represents the gas compressibility factor corresponding to temperature T1 and pressure P1; Z2 represents the gas compressibility factor corresponding to temperature T2 and pressure P2; and T2 represents the actual operating temperature at the second preset time.

[0010] Preferably, the deviation threshold is V gn Relative to V g0 The percentage threshold is set, and the allowable fluctuation range is ±5% to ±10%.

[0011] Preferably, when V gn Below V g0 When the lower limit threshold is reached, control the liquid pump to stop adjusting for a longer period to reduce the upward trend of the liquid level. When V gn Higher than V g0 When the upper limit threshold is reached, the liquid pump is controlled to increase the flow rate within the adjustment time to improve the liquid level recovery speed; The duration of the adjustment is within a preset collection interval; The sampling interval is set according to the changes in the degree of liquid level deviation.

[0012] Preferably, the adjustment of the liquid pump is a graded adjustment strategy, including: When V gn With V g0 No adjustment is made if the deviation between them does not exceed the preset deviation threshold; When V gn With V g0 When the deviation exceeds the preset deviation threshold, different adjustment amounts are output according to the deviation amplitude.

[0013] Preferably, the minimum interval between two adjacent liquid pump adjustment actions is limited by the first timer and the second timer to form a preset control cycle, so that only one two-point differential sampling and ΔP calculation are triggered in each control cycle.

[0014] Preferably, the control loop employs a two-stage strategy of benchmark learning and bias correction, including: The first cycle establishes a baseline volume V. g0 ; Subsequent cycles are based on the gas phase equivalent volume V of the current period n. gn With the reference volume V g0 Adjust the deviation accordingly.

[0015] According to a second aspect of the embodiments of this application, an automatic liquid level control system for a multiphase continuous flow reactor is provided, comprising: Mass flow controllers, liquid pumps, reactors, electronic pressure controllers, thermocouples, and PLC controllers; The reactor is connected to a mass flow controller, a liquid pump, and an electronic pressure controller; The temperature measuring thermocouple is installed inside the reactor to collect the temperature value inside the reactor; The electronic pressure controller is used to collect pressure information from the gas outlet side; The PLC controller is connected to a mass flow controller, a liquid pump, an electronic pressure controller, and a temperature measuring thermocouple; Gas enters from the mass flow controller, passes through the reactor, and exits from the electronic pressure controller; The liquid enters from the liquid pump, passes through the reactor, and flows out from the tail end of the reactor; The PLC controller is used to execute the automatic liquid level control method for a multiphase continuous flow reactor as described in any of the above.

[0016] Preferably, a filter device is provided at the bottom of the reactor to retain solid substances inside the reactor.

[0017] The technical solution provided in this application may include the following beneficial effects: This application provides an automatic liquid level control method and system for a multiphase continuous flow reactor. By acquiring gas phase parameters, calculating the equivalent gas phase volume, and adjusting the liquid pump flow rate based on the deviation, the automatic liquid level stabilization is achieved. This solves the problem that liquid level sensors cannot be installed or interfere with the reaction environment under special operating conditions, and realizes automatic liquid level stabilization control without relying on direct measurement.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] Figure 1 This is a schematic flowchart of an automatic liquid level control method for a multiphase continuous flow reactor provided in one embodiment of this application; Figure 2 This is a schematic diagram of the structure of an automatic liquid level control system for a multiphase continuous flow reactor provided in one embodiment of this application.

[0021] Figure reference numerals: mass flow controller-1; liquid pump-2; reactor-3; electronic pressure controller-4; temperature measuring thermocouple-5; PLC controller-6; filtration device-7. Detailed Implementation

[0022] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0023] An automatic liquid level control method for a multiphase continuous flow reactor is provided, applicable to scenarios where the gas and liquid phases flow continuously simultaneously and without the use of a liquid level sensor for direct measurement of the liquid level height. (Refer to...) Figure 1 ,include: S1. Obtain the equivalent flow rate of gas inlet, the temperature inside the reactor, and the pressure information at the gas outlet. S2. When the preset identification conditions are met, the electronic pressure controller on the gas outlet side is closed within the preset acquisition time t, causing a pressure change in the gas phase space inside the reactor. The first pressure value P1 is acquired at the first preset moment after the closing action begins, and the second pressure value P2 is acquired at the second preset moment before the preset acquisition time t ends and the reactor is reopened. The pressure change ΔP within the preset acquisition time t is calculated based on the first pressure value P1 and the second pressure value P2. S3. Based on the preset acquisition time t, the equivalent gas inlet flow rate A, the temperature T and pressure change ΔP inside the reactor, calculate the equivalent gas volume V between the reactor liquid surface and the gas phase outlet under actual operating conditions according to the gas state relation equation. g ; S4. Use the equivalent gas volume obtained from the initial identification under the target state as the reference volume V. g0 ; S5. Enter the operation control loop, periodically execute steps S2 to S3 to obtain the gas phase equivalent volume V for the current period n. gn Calculate V gn With V g0 The deviation between the two is monitored, and the liquid pump flow rate is adjusted when the deviation exceeds a preset deviation threshold, so that V gn Back to V g0 Within the corresponding allowable fluctuation range, the liquid level can be automatically stabilized.

[0024] It should be noted that: Multiphase continuous flow reactor: refers to a device used for continuous multiphase (e.g., gas phase, liquid phase, solid phase) reactions. Its characteristics are that reactants can continuously enter and products can continuously flow out, so as to achieve efficient chemical transformation or physical process.

[0025] Electronic pressure controller on the gas outlet side: This refers to a device installed at the gas phase outlet of the reactor. Its function is to precisely control or regulate the pressure at the gas phase outlet and to briefly close or open it according to instructions for pressure measurement or system identification. In atmospheric pressure reactions, this device can also be adjusted to a solenoid shut-off valve and a pressure transmitter to achieve the same effect.

[0026] Preset identification conditions: The identification calculation V is triggered only when the reactor is in steady-state operation, the pressure and temperature meet the stability criteria, the inlet flow feedback is effective and the system is not overpressured, the actuator is fault-free, and a short-term shutdown of the gas outlet does not cause a significant change in the liquid level. g .

[0027] Preset acquisition duration t: refers to the specific length of time the electronic pressure controller remains in the off state during pressure change measurement. This duration is an important parameter for calculating the equivalent gas volume.

[0028] Equivalent gas inlet flow rate A: This refers to the gas flow rate entering the reactor under standard conditions (e.g., standard temperature and standard pressure), usually expressed as volumetric flow rate. This flow rate value is an important basis for calculating the amount of gas entering the reactor.

[0029] The temperature inside the reactor refers to the actual temperature of the gas or liquid phase inside the reactor. This temperature is a key parameter in the gas state equation when calculating the equivalent volume of the gas phase.

[0030] Pressure change ΔP: refers to the difference in pressure rise in the gas phase space inside the reactor due to the continuous entry of gas into the reactor within a preset sampling time t. This difference is an important indicator reflecting the volume change of the gas phase space.

[0031] Gas phase equivalent volume V g This refers to the equivalent volume occupied by the gas phase space between the liquid surface and the gas phase outlet in the reactor. Changes in this volume directly reflect changes in the liquid level height within the reactor.

[0032] Reference volume V g0 This refers to the equivalent gas volume determined by an identification method during the system's initial stable operation or under specific calibration conditions. This volume serves as a reference standard for subsequent liquid level control.

[0033] Preset deviation threshold: refers to the current gas phase equivalent volume V gn With reference volume V g0 The maximum allowable deviation range between V and V. gn With V g0 When the deviation exceeds this range, the system will trigger an adjustment action.

[0034] Liquid pump flow rate: refers to the output flow rate of the liquid pump that controls the liquid entering the reactor. By adjusting this flow rate, the liquid level in the reactor can be changed, thereby achieving liquid level stability.

[0035] This embodiment provides an automatic liquid level control method for a multiphase continuous flow reactor, the specific implementation of which is as follows: First, in step S1, it is necessary to obtain the standard gas inlet flow rate, the temperature inside the reactor, and the pressure information at the gas outlet. This information can be obtained through a mass flow controller, a thermocouple, and an electronic pressure controller.

[0036] Secondly, in step S2, when the preset identification conditions are met, the electronic pressure controller on the gas outlet side is closed within a preset acquisition time t, so that an observable pressure change is formed in the gas phase space inside the reactor. The first pressure value P1 is acquired at the first preset moment after the closing action begins, and the second pressure value P2 is acquired at the second preset moment before the preset acquisition time t ends and the reactor reopens. The pressure change ΔP = P2 - P1 is calculated.

[0037] Next, in step S3, based on the preset acquisition time t, the standard gas inlet flow rate A, the temperature T and pressure change ΔP inside the reactor, the equivalent gas volume V between the reactor liquid surface and the gas phase outlet is calculated according to the gas state relation equation. g This calculation process can be completed by a PLC controller, which substitutes various parameters into the gas state equation for solution.

[0038] Then, in step S4, the gas phase equivalent volume obtained from the first identification is used as the reference volume V. g0。 The reference volume V g0 It can be set to a fixed value and will not be updated or adjusted during system operation.

[0039] Finally, in step S5, the system enters the operation control loop, periodically executing steps S2 to S3 above to obtain the gas phase equivalent volume V for the current period n. gn Then, calculate V. gn With V g0 The deviation between the two is monitored, and the liquid pump flow rate is adjusted when the deviation exceeds a preset deviation threshold, so that V gn Back to V g0 Within the corresponding allowable fluctuation range, the liquid level can be automatically stabilized.

[0040] This embodiment indirectly calculates the equivalent gas volume between the reactor liquid surface and the gas phase outlet by utilizing the pressure change generated when the gas phase outlet is briefly closed, instead of directly measuring the liquid level using a level sensor. The change in this equivalent gas volume directly reflects the change in liquid level within the reactor. By using the initially identified volume as a baseline and periodically calculating the deviation between the current volume and the baseline volume during subsequent operation, and adjusting the liquid pump flow rate based on the deviation, this method effectively solves the problem of unstable liquid level control and the unsuitability of installing level sensors in gas-liquid-solid multiphase reactors. Thus, it achieves automatic and stable control of the liquid level in a multiphase continuous flow reactor, avoiding manual intervention and improving automation and production efficiency.

[0041] Specifically, the identification criteria include: The liquid level in the reactor remains stable for a preset duration, and turning off the electronic pressure controller within a preset sampling duration t will not affect the continuity of the reaction process.

[0042] The identification conditions are designed to ensure that the calculation of the gas-phase equivalent volume is performed when the system is in a suitable state, thereby improving measurement accuracy and maintaining the stability of the reaction process. When performing gas-phase equivalent volume identification, it is first necessary to manually determine whether the liquid level in the reactor remains stable within a preset duration. This "preset duration" refers to a sufficiently long period of time to confirm that the liquid level does not fluctuate or change significantly, typically V. g The variation within the intervals between tests is no greater than 10%, thus ensuring that the gas phase volume remains relatively constant during pressure measurements. Liquid level stability can be assessed by monitoring historical liquid level control data, the stability of the liquid pump flow rate, or the equivalent gas phase volume V. gn With reference volume V g0 This is achieved through the deviation trend. For example, if V has been trending upwards over a certain period of time... gn With V g0 If the deviation is always within the allowable fluctuation range, the liquid level can be considered stable.

[0043] Furthermore, the identification condition requires that shutting down the electronic pressure controller within the preset acquisition duration t will not affect the continuity of the reaction process. This means that while the electronic pressure controller will be temporarily shut down during the acquisition of pressure change ΔP, the duration t must be carefully set to ensure that it does not cause any substantial interference to the normal operation of the continuous flow reactor. For example, this duration t should be short enough to avoid excessive pressure accumulation in the reactor, reactant retention, or obstruction of product discharge, thereby maintaining the continuous inflow and outflow of reactants and the smooth progress of the reaction process. The preset acquisition duration t can be determined experimentally or through simulation calculations based on the specific dimensions of the reactor, gas flow rate, reaction kinetics, and the requirements for process continuity; it is typically several seconds to tens of seconds.

[0044] Through the above technical solution, when performing gas phase equivalent volume identification, the system can ensure that the liquid level in the reactor remains stable for a preset duration, thereby avoiding the loss of gas phase equivalent volume V due to liquid level fluctuations. g The problem of inaccurate calculations is addressed. Simultaneously, by limiting the preset acquisition time 't' of shutting down the electronic pressure controller, the continuity of the reaction process is not affected, effectively avoiding interference with the normal operation of the continuous flow reactor during identification, thus ensuring the stability of the reaction process and the consistency of product quality. This enables the automatic level control method to achieve precise and undisturbed control of the liquid level in the continuous flow reactor without relying on a level sensor, while ensuring measurement accuracy, thereby improving the system's reliability and applicability.

[0045] Specifically, the equivalent gas volume V between the reactor liquid surface and the gas phase outlet is calculated according to the gas state equation. g ,include: Calculate the equivalent volume of gas entering the reactor within the preset data acquisition time t under actual operating conditions: ΔV=At; Calculate the pressure change ΔP within the data acquisition time t: ΔP = P2 - P1; When the system is in a relatively steady state, ΔP = f(ΔV, T1, P1); Wherein, T1 represents the actual operating temperature at the first preset time; In the ideal gas state, ΔP = P1ΔV / V g Then V g =P1ΔV / ΔP; In a non-ideal gas state, P2T1 / P1T2=Z2(V g +ΔV) / Z1V g Then V g =ΔV×Z2P1T2 / (Z1P2T1-Z2P1T2); Where Z1 represents the gas compressibility factor corresponding to temperature T1 and pressure P1; Z2 represents the gas compressibility factor corresponding to temperature T2 and pressure P2; and T2 represents the actual operating temperature at the second preset time.

[0046] It should be noted that when T1=T2, V g =ΔV×Z2P1 / (Z1P2-Z2P1; Furthermore, when Z1 = Z2, V g =ΔV×Z2P1 / (Z1P2-Z2P1)can be simplified to V g =P1ΔV / ΔP.

[0047] When multiple gases are present, the equation of state for a mixed gas can also be used for calculation, which will not be elaborated here.

[0048] Through the detailed calculation steps described above, this application provides a method for accurately and reliably calculating the equivalent gas volume V between the reactor liquid surface and the gas phase outlet. g The method clarifies the process from the standard gas inlet flow rate A, the preset acquisition time t, the reactor temperature T, and the pressure change ΔP to the final equivalent gas phase volume V. g The complete derivation process includes the calculation of the standard gas volume, the conversion of gaseous substance amounts, the standardization of temperature units, and the precise application of the gas state equation. This explicit calculation method, based on physical laws, effectively avoids errors introduced by unclear calculation methods or improper parameter handling, ensuring the accurate calculation of the gas-phase equivalent volume V. g The calculation results exhibit high accuracy and repeatability. Therefore, in the operational control loop, the gas-phase equivalent volume V for the current period n can be determined more accurately. gn With reference volume V g0 The deviation between these parameters allows for more precise and timely adjustment of the liquid pump flow rate, significantly improving the accuracy and stability of automatic liquid level control in multiphase continuous flow reactors, and ensuring the continuity and efficiency of the reaction process.

[0049] In practice, the deviation threshold is V. gn Relative to V g0 The percentage threshold is set, and the allowable fluctuation range is ±5% to ±10%.

[0050] In this embodiment, the system does not determine whether adjustment is needed based on a fixed volume difference value, but rather based on V. gn With V g0 The relative proportion between them triggers the control action. For example, when V gn With V g0 The difference divided by V g0When the obtained percentage exceeds a preset value, the liquid level is considered to have deviated from the allowable range. This percentage-based threshold setting method allows the sensitivity of the liquid level control to adapt to the actual size of the gas phase space within the reactor, maintaining relatively consistent control accuracy and response characteristics regardless of changes in reactor size or operating conditions. Furthermore, this application defines the allowable fluctuation range as ±5% to ±10%. This range provides guidance for the acceptable level fluctuation amplitude in actual system operation. For example, the percentage threshold can be set to a specific value within this range, such as ±5%, ±7%, or ±10%, depending on specific process requirements and the need for level stability. A smaller percentage threshold means stricter level control, requiring more frequent adjustments to maintain the liquid level within a narrower range; while a larger percentage threshold allows for greater level fluctuations, potentially reducing adjustment frequency and lowering the burden on the control system. This flexible setting method allows this approach to better adapt to the varying level control accuracy requirements of different processes.

[0051] In the automatic level control process of a multiphase continuous flow reactor, the equivalent gas volume V is periodically acquired. gn and with reference volume V g0 When comparing the two, if the deviation exceeds the preset threshold, the flow rate of the liquid pump can be adjusted. However, if there is a lack of a fine adjustment strategy, the liquid level recovery speed may be slow, or the liquid level may not be effectively and timely adjusted to the target range when the liquid level deviates significantly, affecting the stability and continuity of the reaction process.

[0052] Based on this, when V gn Higher than V g0 When the upper limit threshold is reached, the liquid pump is controlled to increase the flow rate within the adjustment time to improve the liquid level recovery speed; The duration of the adjustment is within a preset collection interval; The sampling interval is set according to the changes in the degree of liquid level deviation.

[0053] Specifically, when the system detects the gas phase equivalent volume V of the current period n gn Less than the reference volume V g0 When the lower limit is reached, it indicates that the liquid level in the reactor is higher than the expected value, and there is a trend of the liquid level continuing to rise.

[0054] To suppress this upward trend, the PLC controller sends a command to the liquid pump to pause operation for a set adjustment period. By temporarily stopping the liquid pump's inflow, the further rise in liquid level can be effectively slowed or prevented, providing the system with buffer time to restore balance, or allowing the liquid in the reactor to flow out naturally, thus gradually lowering the liquid level back to the target range.

[0055] Conversely, when the system detects the gas phase equivalent volume V of the current period n... gn Greater than the reference volume V g0 When the upper limit is reached, it indicates that the liquid level in the reactor is lower than the desired value, and liquid needs to be replenished quickly to raise the liquid level.

[0056] At this point, the PLC controller will control the liquid pump to operate at a flow rate higher than the normal operating rate within a set adjustment period. By increasing the liquid pump flow rate, more liquid can be rapidly injected into the reactor, thereby accelerating the rise of the liquid level and allowing it to return to the reference volume V more quickly. g0 Within the corresponding allowable fluctuation range, ensure the continuity and stability of the reaction process. The increased flow rate can be a preset fixed increment, or it can be increased proportionally according to the magnitude of the deviation.

[0057] It should be noted that the adjustment time is set within the preset collection interval; the collection interval is set according to the change in the degree of liquid level deviation.

[0058] Through the above technical solution, this application provides a differentiated adjustment strategy for the direction of liquid level deviation, that is, when the equivalent gas volume V gn Below the reference volume V g0 When V reaches the lower threshold, the liquid pump is stopped for a period of time to suppress the rise in liquid level; while when V gn Higher than V g0 When the upper limit threshold is reached, the liquid pump flow rate is increased within the adjustment period to accelerate liquid level recovery.

[0059] Therefore, this application can effectively avoid the problems of slow liquid level recovery or over-adjustment, significantly improve the accuracy and stability of liquid level control, and ensure that the multiphase continuous flow reactor can maintain efficient and continuous operation under various operating conditions.

[0060] Furthermore, the liquid pump is regulated using a graded regulation strategy, including: When V gn With V g0 No adjustment is made if the deviation between them does not exceed the preset deviation threshold; When V gn With V g0 When the deviation exceeds the preset deviation threshold, different adjustment amounts are output according to the deviation amplitude.

[0061] The graded adjustment strategy refers to adjusting the liquid level based on the level deviation (i.e., V). gn With V g0The adjustment action is divided into different levels or ranges based on the magnitude of the deviation (between the two values), and a corresponding adjustment intensity or mode is set for each level. This strategy aims to enable the liquid level control system to respond to liquid level changes more precisely and intelligently, avoiding over- or under-adjustment problems that may arise from a single adjustment mode. For example, multiple deviation thresholds can be set, dividing the deviation range into multiple levels such as "small deviation," "medium deviation," and "large deviation," with each level corresponding to a different liquid pump flow rate adjustment amount or adjustment duration.

[0062] When V gn With V g0 When the deviation between the parameters is within a preset allowable fluctuation range (i.e., does not exceed a preset deviation threshold), the system does not trigger the liquid pump's adjustment action. This technical feature defines a "no-adjustment region" or "dead zone." This effectively avoids frequent adjustments due to small, normal system fluctuations, thereby reducing liquid pump wear, lowering control system energy consumption, and preventing unnecessary system oscillations introduced by overly sensitive adjustments, thus improving control stability and reliability.

[0063] When V gn With V g0 When the deviation exceeds a preset deviation threshold, the system determines the adjustment amount of the liquid pump based on the actual magnitude of the deviation (i.e., the deviation amplitude). This technical feature is the core embodiment of the graded adjustment strategy. Specifically, the larger the deviation amplitude, the larger the system output adjustment amount to correct the liquid level more quickly; conversely, the smaller the deviation amplitude, the smaller the system output adjustment amount to avoid over-adjustment. For example, multiple graded thresholds can be set. When the deviation is within the first threshold range, the liquid pump flow rate increases or decreases by a small amount; when the deviation is within the second, larger threshold range, the liquid pump flow rate increases or decreases by a larger amount. This graded response mechanism allows the system to provide appropriate adjustment force according to actual needs, thereby achieving rapid and stable liquid level recovery.

[0064] By employing a graded control strategy, this application significantly improves the precision and robustness of automatic level control in multiphase continuous flow reactors. When the equivalent gas volume V... gn With reference volume V g0When the deviation is within the allowable fluctuation range, the system does not adjust, effectively avoiding frequent adjustments caused by small fluctuations. This reduces energy consumption of the control system and wear on the actuators, and suppresses system oscillations that may be caused by overly sensitive adjustments, ensuring the stability of the reaction process. When the deviation exceeds a preset threshold, the system can output different adjustment amounts according to the actual magnitude of the deviation. This means that for smaller deviations, the system will apply gentle adjustments to avoid overshoot; for larger deviations, the system will apply stronger adjustments to accelerate the liquid level recovery speed and effectively cope with sudden disturbances. This refined, graded adjustment mechanism allows the liquid level to return to the target range more quickly and smoothly, significantly improving the accuracy and response efficiency of liquid level control, thereby ensuring the stability of the continuous flow reaction process and the consistency of product quality.

[0065] It should be noted that the minimum interval between two adjacent liquid pump adjustment actions is limited by the first timer and the second timer to form a preset control cycle, so that only one two-point differential sampling and ΔP calculation are triggered in each control cycle.

[0066] Specifically, the first timer is a hardware or software module used for precise timing and event triggering. At the hardware level, it can be a timer / counter module within a microcontroller; at the software level, it can be a timing service provided by the operating system or a custom timing function. Its main function is to provide a precise time reference to ensure accurate recording of the pressure values ​​P1 and P2 within the reactor at the first preset time after the electronic pressure controller's shutdown action begins and at the second preset time before reopening after the shutdown continues for a preset sampling duration t. This precise timing control is crucial for obtaining accurate pressure changes ΔP, because pressure changes are a dynamic process, and any deviation in sampling timing can introduce measurement errors. For example, the first timer can be configured to initiate a timing sequence after the electronic pressure controller's shutdown command is issued. When the timing reaches the first preset time, an analog-to-digital converter (ADC) is triggered to sample the signal from the pressure sensor, and the result is stored as P1. Subsequently, the timing continues, and when the second preset time is reached, the ADC is triggered again to sample, and the result is stored as P2.

[0067] The sampling window is a time interval that defines the time range for collecting pressure values ​​P1 and P2 during pressure measurement. It ensures that pressure sampling occurs within the effective period when the electronic pressure controller is off, i.e., after observable pressure changes begin to form in the gas phase space and before the electronic pressure controller reopens. This helps eliminate transient noise or non-steady-state effects that may exist during sampling, thereby improving the reliability of pressure measurement data. The starting point of the sampling window can be set to a short time delay after the electronic pressure controller begins to close, allowing the system to reach a relatively stable closed state. The ending point of the sampling window is set before the electronic pressure controller reopens. Both the first and second preset times fall within this sampling window.

[0068] The first preset time point refers to the specific time point used to collect the first pressure value P1 after the electronic pressure controller begins its shut-off action; the second preset time point refers to the specific time point used to collect the second pressure value P2 after the electronic pressure controller remains shut off until the preset collection duration t ends and before it reopens. Both times are preset by the system. The selection of these two times directly affects the accuracy of the pressure change ΔP. The first preset time point should be selected after gas begins to accumulate in the gas phase space and an observable pressure change occurs, but not too late, so as not to miss the initial state. The second preset time point should be selected when the preset collection duration t is about to end, to fully reflect the pressure rise caused by gas accumulation, while avoiding the transient effects caused by the electronic pressure controller reopening. These times can be optimized and determined through experiments or simulations based on the reactor volume, gas flow rate, response speed of the electronic pressure controller, and the required measurement accuracy. For example, the first preset time point can be set to 100 milliseconds after the shut-off action begins, and the second preset time point can be set to the preset collection duration t minus 100 milliseconds, with the preset collection duration t being 200 milliseconds.

[0069] Two-point differential sampling is a method to obtain the change in pressure by collecting data at two different time points and calculating the difference between them. In this method, it is used to directly calculate the pressure change ΔP = P2 - P1 by collecting pressure data at a first preset time point P1 and at a second preset time point P2. This method effectively filters out common-mode noise and slowly changing drift in the system because these factors typically do not change much between the two sampling points and can be canceled out by subtraction, thus improving the measurement accuracy of ΔP. The PLC controller receives the P1 and P2 data recorded by the first timer at the first and second preset times, and then performs a simple subtraction operation to obtain ΔP.

[0070] The second timer is another hardware or software module used for timing and controlling time intervals. Its main function is to limit the minimum interval between two consecutive liquid pump adjustment actions. This prevents the control system from adjusting the liquid pump too frequently, thereby avoiding system oscillation, over-adjustment, and wear on the liquid pump and related actuators. Simultaneously, it provides sufficient response time for the system, allowing the effect of each adjustment to be fully realized and preventing the next adjustment from being performed before the effect is apparent. The second timer can be configured to start timing after each liquid pump adjustment action is completed. Even if the liquid level deviation exceeds the threshold again before the preset minimum interval time is reached, the system will not immediately trigger the next adjustment. Only after the minimum interval time is reached will the system allow the next adjustment judgment and execution.

[0071] A preset control cycle refers to the time interval defined by the second timer, encompassing a complete liquid level identification (two-point differential sampling and ΔP calculation) and possible liquid pump adjustment actions. By setting a preset control cycle, the system can complete liquid level identification and necessary adjustments within a stable time frame, ensuring the orderliness and stability of the control process. It balances the timeliness of control and the stability of the system, avoiding unnecessary frequent operations. The preset control cycle is typically defined by the minimum interval time set by the second timer. Within this cycle, the system executes a complete liquid level identification process (including steps S2 and S3) and determines whether to adjust the liquid pump based on the identification result.

[0072] Within each preset control cycle, only one two-point differential sampling and ΔP calculation is triggered, meaning only steps S2 and S3 are executed once, and only one acquisition of pressures P1 and P2 and one calculation of ΔP are performed. This mechanism aims to optimize system resource utilization and reduce unnecessary computational burden. Since liquid level changes typically have a certain inertia, excessively frequent pressure sampling and volume calculations may not significantly improve control accuracy. For mechanical actuators like peristaltic pumps, frequent start-stop cycles or drastic speed changes can significantly reduce the lifespan of hoses and rollers. This interval ensures the system has sufficient time to respond to the previous adjustment, avoiding over-adjustment ("water hammer effect"), and greatly improving system stability and equipment lifespan.

[0073] By introducing a first timer and two-point differential sampling technology, the acquisition timing of pressures P1 and P2 can be precisely controlled, effectively filtering out measurement noise and drift, thereby improving the measurement accuracy of pressure change ΔP and consequently making the calculation of the gas-phase equivalent volume Vg more accurate. Simultaneously, by using a second timer to limit the minimum interval between two adjacent liquid pump adjustment actions and forming a preset control cycle, it is ensured that two-point differential sampling and ΔP calculation are triggered only once within each control cycle. This not only avoids system oscillations and actuator wear caused by frequent adjustments but also optimizes the utilization of computational resources, improving the operating efficiency and stability of the control system. This precise sampling mechanism combined with reasonable control cycle management enables the automatic level control method to achieve more stable and efficient level control without using a level sensor, effectively improving the reactor's operational reliability and process control accuracy.

[0074] It should be noted that the control loop employs a two-stage strategy of benchmark learning and bias correction, including: The first cycle establishes a baseline volume V. g0 ; Subsequent cycles are based on the gas phase equivalent volume V of the current period n. gn With the reference volume V g0 Adjust the deviation accordingly.

[0075] This control loop strategy aims to optimize the robustness and accuracy of automatic level control. The "reference learning" phase focuses on establishing a reliable level reference point, while the "deviation correction" phase maintains the level continuously and dynamically based on this reference point. This phased design allows the system to better adapt to actual operating conditions and avoids control deviations caused by a single fixed reference.

[0076] Specifically, during system startup or reinitialization, the system enters the "initial loop" phase. In this phase, the system executes steps S1 to S4 of the method described above, which involves a series of measurements and calculations to obtain an initial gas-phase equivalent volume V. g To ensure V g0 The accuracy and stability of the value can be ensured by performing multiple measurements and taking the average, or by calculating V after confirming that the internal conditions of the reactor (such as temperature, pressure, and inlet flow rate) have reached a stable state. g Set as the reference volume V g0 This process ensures that subsequent controls have a reliable starting reference.

[0077] In the reference volume V g0After establishment, the system enters the "subsequent loop" phase, which is the operation control loop. During this phase, the system periodically executes steps S2 and S3 of the above method to calculate the gas-phase equivalent volume V for the current period n. gn Then, the system will calculate V. gn With the established reference volume V g0 The difference between them. When this deviation exceeds the preset allowable fluctuation range or deviation threshold, the system will adjust the flow rate of the liquid pump accordingly based on the direction and magnitude of the deviation, such as increasing or decreasing the flow rate of the liquid pump, to prompt V gn Returning to V g0 Within the corresponding allowable fluctuation range, the liquid level can be automatically stabilized.

[0078] By employing a two-stage strategy of benchmark learning and bias correction, this application can effectively solve the problem of the benchmark volume V obtained in the initial identification. g0 Potential initial inaccuracies may exist. During the "first cycle," the system ensures the baseline volume V through a dedicated setup process. g0 The accuracy and representativeness of this data provide a solid foundation for subsequent level control. The deviation correction mechanism in the "subsequent cycle" can then be based on this reliable reference V. g0 For the current gas phase equivalent volume V gn Real-time monitoring and adjustment enable precise and stable control of the reactor liquid level. This strategy not only improves the robustness of the liquid level control, making it less susceptible to fluctuations in initial conditions, but also ensures high-precision maintenance of the liquid level during long-term operation through continuous deviation correction, significantly enhancing the stability and reliability of the multiphase continuous flow reactor.

[0079] Example 2 Figure 2 This is a schematic diagram of the structure of an automatic liquid level control system for a multiphase continuous flow reactor according to an embodiment of this application, with reference to... Figure 2 An automatic level control system for a multiphase continuous flow reactor includes: Mass flow controller 1, liquid pump 2, reactor 3, electronic pressure controller 4, temperature measuring thermocouple 5, and PLC controller 6; Reactor 3 is connected to mass flow controller 1, liquid pump 2 and electronic pressure controller 4; The temperature measuring thermocouple 5 is installed inside the reactor 3 to collect the temperature value inside the reactor 3; Electronic pressure controller 4 is used to collect pressure information on the gas outlet side; PLC controller 6 is connected to mass flow controller 1, liquid pump 2, electronic pressure controller 4 and temperature measuring thermocouple 5; Gas enters from mass flow controller 1, passes through reactor 3, and flows out from electronic pressure controller 4; The liquid enters from liquid pump 2, passes through reactor 3, and flows out from the tail end of reactor 3; PLC controller 6 is used to execute the automatic liquid level control method for the multiphase continuous flow reactor as described in the above embodiments.

[0080] This system avoids reliance on level sensors by combining an electronic pressure controller 4 with a temperature-measuring thermocouple 5 in a collaborative manner, and executing indirect liquid level calculation logic based on gas phase pressure changes through a PLC controller 6. Specifically, under preset identification conditions, the PLC controller 6 briefly shuts down the electronic pressure controller 4, creating observable pressure changes in the gas phase space inside the reactor 3, and collects the pressure values ​​at the start and end of the shutdown to calculate the pressure change. Combining the standard gas inlet flow rate, reactor temperature, and preset acquisition duration, the PLC controller 6 derives the equivalent gas phase volume between the reactor liquid surface and the gas phase outlet based on the gas state equation. The initially identified equivalent gas phase volume serves as a reference volume. During subsequent operation, the current equivalent gas phase volume is periodically acquired and compared with the reference volume. When the deviation exceeds a preset threshold, the liquid pump flow rate is adjusted to maintain the liquid level within a stable range. This ingenious technical concept utilizes the dynamic characteristics of the gas phase space to indirectly characterize liquid level changes, achieving automatic and stable control of the liquid level in a multiphase reactor without the need for a level sensor.

[0081] In a multiphase continuous flow reactor, solid substances may be generated during the reaction process. If these solid substances are not dealt with in time, they may cause blockage inside the reactor, affecting the continuous flow of fluid and thus interfering with the accuracy of automatic level control and the stability of the reaction.

[0082] In this regard, this application further proposes that a filter device 7 is provided at the bottom of the reactor to retain solid matter inside the reactor.

[0083] The filter device 7 is a device for separating solid particles from a fluid. Its function is to effectively trap solid substances generated during the reaction process, preventing them from flowing out with the liquid or accumulating in key areas inside the reactor. Specifically, the filter device 7 can take various forms. For example, it can be a filter screen with a specific pore size, such as a stainless steel filter screen, whose pore size can be customized according to the particle size distribution of the reaction products to ensure effective trapping of solids without significantly increasing fluid resistance; or it can be a porous medium, such as a sintered metal filter element, ceramic filter element, or fiber filter element. These media typically have high porosity and a large specific surface area, enabling them to capture smaller particles and provide a finer filtration effect.

[0084] Placing the filter device 7 at the bottom of the reactor 3 is an effective strategy that utilizes gravity. In a multiphase continuous flow reactor, solid particles naturally settle to the bottom under gravity; therefore, placing the filter device at the bottom allows for the concentrated treatment of the settled solids. Simultaneously, the bottom of the reactor 3 is typically where the liquid flows out; filtration at this location ensures the purity of the outflowing liquid.

[0085] By retaining solid matter inside reactor 3, solid blockage of the liquid outlet or downstream pipeline can be avoided, maintaining smooth continuous flow and preventing solid matter from entering downstream equipment, thereby ensuring the stable operation of the entire reaction system.

[0086] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0087] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means at least two.

[0088] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0089] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0090] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0091] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0092] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0093] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0094] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An automatic liquid level control method for a multiphase continuous flow reactor, applicable to scenarios where the gas and liquid phases flow continuously simultaneously and without the use of a liquid level sensor for direct measurement of the liquid level height, characterized in that... include: S1. Obtain the equivalent flow rate of gas inlet, the temperature inside the reactor, and the pressure information at the gas outlet. S2. When the preset identification conditions are met, the electronic pressure controller on the gas outlet side is closed within the preset acquisition time t, causing a pressure change in the gas phase space inside the reactor. The first pressure value P1 is acquired at the first preset moment after the closing action begins, and the second pressure value P2 is acquired at the second preset moment before the preset acquisition time t ends and the reactor is reopened. The pressure change ΔP within the preset acquisition time t is calculated based on the first pressure value P1 and the second pressure value P2. S3. Based on the preset acquisition time t, the equivalent gas inlet flow rate A, the temperature T and pressure change ΔP inside the reactor, calculate the equivalent gas volume V between the reactor liquid surface and the gas phase outlet under actual operating conditions according to the gas state relation equation. g ; S4. Use the equivalent gas volume obtained from the initial identification under the target state as the reference volume V. g0 ; S5. Enter the operation control loop, periodically execute steps S2 to S3 to obtain the gas phase equivalent volume V for the current period n. gn Calculate V gn With V g0 The deviation between the two is monitored, and the liquid pump flow rate is adjusted when the deviation exceeds a preset deviation threshold, so that V gn Back to V g0 Within the corresponding allowable fluctuation range, the liquid level can be automatically stabilized.

2. The method according to claim 1, characterized in that, The identification conditions include: The liquid level in the reactor remains stable for a preset duration, and turning off the electronic pressure controller within a preset sampling duration t will not affect the continuity of the reaction process.

3. The method according to claim 1, characterized in that, Calculate the equivalent gas volume V between the reactor liquid surface and the gas phase outlet under actual operating conditions using the gas state equation. g ,include: Calculate the equivalent volume of gas entering the reactor within the preset data acquisition time t under actual operating conditions: ΔV=At; Calculate the pressure change ΔP within the data acquisition time t: ΔP = P2 - P1; When the system is in a relatively steady state, ΔP = f(ΔV, T1, P1); Wherein, T1 represents the actual operating temperature at the first preset time; In the ideal gas state, ΔP = P1ΔV / V g Then V g =P1ΔV / ΔP; In a non-ideal gas state, P2T1 / P1T2=Z2(V g +ΔV) / Z1V g Then V g =ΔV×Z2P1T2 / (Z1P2T1-Z2P1T2); Where Z1 represents the gas compressibility factor corresponding to temperature T1 and pressure P1; Z2 represents the gas compressibility factor corresponding to temperature T2 and pressure P2; and T2 represents the actual operating temperature at the second preset time.

4. The method according to claim 1, characterized in that, The deviation threshold is V gn Relative to V g0 The percentage threshold is set, and the allowable fluctuation range is ±5% to ±10%.

5. The method according to claim 4, characterized in that, When V gn Below V g0 When the lower limit threshold is reached, control the liquid pump to stop adjusting for a longer period to reduce the upward trend of the liquid level; When V gn Higher than V g0 When the upper limit threshold is reached, the liquid pump is controlled to increase the flow rate within the adjustment time to improve the liquid level recovery speed; The duration of the adjustment is within a preset collection interval; The sampling interval is set according to the changes in the degree of liquid level deviation.

6. The method according to claim 5, characterized in that, The liquid pump is regulated using a graded regulation strategy, including: When V gn With V g0 No adjustment is made if the deviation between them does not exceed the preset deviation threshold; When V gn With V g0 When the deviation exceeds the preset deviation threshold, different adjustment amounts are output according to the deviation amplitude.

7. The method according to claim 1, characterized in that, The minimum interval between two adjacent liquid pump adjustment actions is limited by the first timer and the second timer to form a preset control cycle, so that only one two-point differential sampling and ΔP calculation are triggered in each control cycle.

8. The method according to claim 1, characterized in that, The control loop employs a two-stage strategy of benchmark learning and bias correction, including: The first cycle establishes a baseline volume V. g0 ; Subsequent cycles are based on the gas phase equivalent volume V of the current period n. gn With the reference volume V g0 Adjust the deviation accordingly.

9. An automatic liquid level control system for a multiphase continuous flow reactor, characterized in that, include: Mass flow controllers, liquid pumps, reactors, electronic pressure controllers, thermocouples, and PLC controllers; The reactor is connected to a mass flow controller, a liquid pump, and an electronic pressure controller; The temperature measuring thermocouple is installed inside the reactor to collect the temperature value inside the reactor; The electronic pressure controller is used to collect pressure information from the gas outlet side; The PLC controller is connected to a mass flow controller, a liquid pump, an electronic pressure controller, and a temperature measuring thermocouple; Gas enters from the mass flow controller, passes through the reactor, and exits from the electronic pressure controller; The liquid enters from the liquid pump, passes through the reactor, and flows out from the tail end of the reactor; The PLC controller is used to execute the automatic liquid level control method for a multiphase continuous flow reactor as described in any one of claims 1-8.

10. The system according to claim 9, characterized in that, The reactor is equipped with a filter at the bottom to trap solid substances inside the reactor.

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