Anti-surge control system and method for dynamic safety margin of MVR steam compressor

Abstract

The invention discloses an MVR steam compressor dynamic safety margin anti-surge control system and method, and relates to the technical field of fluid machinery safety control, and the system comprises a sensor group, an anti-surge valve and a controller, or further comprises a human-computer interaction interface. The method comprises the following steps of parameter acquisition, boundary calculation, margin adjustment, control line generation and prevention and control execution. Surge generation can be predicted and intervened, efficient and safe operation of the compressor is guaranteed, the method is matched with the operation characteristics of the MVR system, a control strategy can be automatically adjusted, operation is convenient, and maintenance is visual.

Description

Technical Field

[0001] This invention relates to the field of fluid machinery safety control technology, specifically to a dynamic safety margin anti-surge control system and method for MVR steam compressors. Background Technology

[0002] MVR evaporation systems, as an energy-saving and environmentally friendly evaporation and concentration process, are widely used in industrial production fields such as chemical, food, and pharmaceutical industries. They are the mainstream high-efficiency concentration equipment in the industry. The steam compressor is the core power component of the MVR evaporation system, and its operating status directly affects the continuity of the entire system's operation and the equipment's service life. Surge is a common unstable flow fault during the operation of a steam compressor. When surge occurs, the internal gas flow and pressure will experience severe periodic fluctuations, leading to strong vibrations in the unit. Long-term or severe surge can directly cause structural damage to the unit, such as seal damage, bearing burnout, or even rotor breakage, affecting the normal progress of the production process. Industrial production has strict requirements for the safe and stable operation of steam compressors.

[0003] Traditional surge control methods mainly include the "fixed margin method" and the "single-parameter limit control method." The fixed margin method avoids surge by setting a fixed control line far from the surge boundary. However, while this method offers high safety, it forces the compressor to operate in an inefficient range for extended periods, leading to a significant increase in operating energy consumption. The single-parameter control method typically monitors only a single parameter, such as outlet pressure, and takes protective action when it exceeds a set upper limit. This method is reactive and cannot prevent the instantaneous impact of surge on the unit. Therefore, in MVR evaporation systems, due to frequent changes in process parameters such as feed flow rate, concentration, and temperature, the operating point of the compressor fluctuates significantly. Existing anti-surge control technologies for steam compressors fail to achieve adaptive adjustment of safety margins, relying solely on fixed parameter execution control. This fails to adapt to the fluctuating process parameters of MVR systems, easily leading to untimely or overly conservative control. Furthermore, existing technologies lack a tiered early warning mechanism, with early warning actions disconnected from formal anti-surge control, failing to form a progressive protection logic and lacking forward-looking adjustment capabilities. Valve opening control lacks precise adjustment basis, easily triggering secondary disturbances in the MVR evaporation system. The steam compressor's anti-interference capability is weak, and the protection process has gaps. Simultaneously, a complete protection system is not constructed by combining opening limits and interlocking protection, resulting in delayed control response, poor adaptability to operating conditions, and an inability to provide continuous and comprehensive anti-surge protection for MVR steam compressors, making it difficult to meet the control requirements of actual production. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a dynamic safety margin anti-surge control system and method for MVR steam compressors that can predict and intervene in surge occurrence, ensure efficient and safe operation of the compressor, adapt to the operating characteristics of MVR system and automatically adjust control strategy, and is convenient to operate and intuitive to maintain.

[0005] The technical solution adopted by the present invention to solve its technical problem is as follows: a dynamic safety margin anti-surge control system for MVR steam compressors, comprising: a sensor group, an anti-surge valve, and a controller; The sensor group includes a flow sensor, a pressure sensor, a temperature sensor, and a speed sensor, which detect the compressor's operating parameters in real time and transmit them to the controller. The anti-surge valve is installed on the return pipeline from the compressor outlet to the inlet and is equipped with an opening feedback component. The opening feedback component transmits the real-time opening signal back to the controller, forming an opening closed-loop regulation circuit. The controller is electrically connected to the sensor group and the anti-surge valve, and the controller is a hardware module with data parsing, calculation and processing and instruction output.

[0006] Preferably, the MVR steam compressor dynamic safety margin anti-surge control system further includes a human-machine interface.

[0007] Preferably, the human-machine interface is an interactive component that establishes an electrical connection with the controller, displays the operating condition point, surge boundary line, anti-surge control line, dynamic safety margin, and early warning information in real time, and is equipped with a manual intervention interface. The manual intervention interface is used to switch between automatic and manual control modes, and allows manual adjustment of the anti-surge valve opening, compressor speed, and control parameters to achieve manual intervention in anti-surge regulation.

[0008] The technical solution adopted by this invention to further solve its technical problem is as follows: A dynamic safety margin anti-surge control method for MVR steam compressors, comprising the following steps: S1. Parameter Acquisition: Real-time acquisition of compressor operating parameters to determine real-time operating condition point, and transmission of the acquired operating parameters to the controller in the form of digital signals; S2, Boundary Calculation: After receiving the compressor's operating parameters, the controller calculates the surge boundary line at the current speed in real time based on the compressor's design performance data, and stores the surge boundary line data in the controller. S3, Margin Adjustment: After receiving the compressor's operating parameters, the controller sets a dynamic safety margin and adaptively adjusts it according to the compressor's stable operating condition and the trend of operating parameter changes, thereby enhancing the compressor's anti-interference capability and storing the adjusted dynamic safety margin data in the controller. S4. Control line generation: The controller calls the surge boundary line data and the adjusted dynamic safety margin data, calculates the anti-surge control line and the real-time operating pressure ratio of the compressor under the current working condition, and then stores the calculation results in the controller. S5. Anti-surge control execution: The controller calls the anti-surge control line data and the real-time operating pressure ratio data of the compressor. First, it calculates the distance between the real-time operating point and the anti-surge control line and performs a warning operation. At the same time, it continuously compares the real-time operating pressure ratio with the anti-surge control line numerically. When the real-time operating pressure ratio is greater than or equal to the anti-surge control line, the controller determines that it has entered the anti-surge trigger state, outputs an anti-surge control action signal, calculates the adjustment opening of the anti-surge valve and controls the action of the anti-surge valve. At the same time, it reduces the speed of the compressor to perform anti-surge control.

[0009] The inventive concept of the method of the present invention is: By collecting the operating parameters of the compressor in real time and transmitting them to the controller, the controller internally stores a compressor surge boundary model, a dynamic safety margin adjustment logic, and an anti-surge control algorithm, which are used to execute the above steps, complete the calculation of the surge boundary line, the adaptive adjustment of the dynamic safety margin, and output in real time the control command for the anti-surge valve. According to the real-time operating state and stability of the compressor, dynamically adjust the safety margin SM between the anti-surge control line and the surge boundary line, and perform forward-looking adjustment based on the deviation between the operating point and the dynamic control line and its change trend. When the system runs stably, a smaller safety margin is adopted to allow the compressor to operate in the high-efficiency area closer to the surge boundary. When the system detects disturbances or rapid changes in working conditions, the safety margin is automatically increased to provide a larger buffer space in advance and enhance the anti-interference ability of the system. The control action adopts an algorithm combining proportional and derivative actions. According to the deviation between the real-time pressure ratio and the dynamic control line and its change rate, the opening of the anti-surge valve is adjusted, making the adjustment process fast and gentle, avoiding violent valve actions from causing secondary disturbances to the system, and keeping the control logic always in line with the real-time operating state of the compressor. In addition, the system also sets up a multi-level warning mechanism to give an early warning when the operating point is close to the control line, providing an intervention window for operators or the upper-level control system.

[0010] Preferably, in step S1, the operating parameters of the compressor are collected by a sensor group supporting the compressor. The sensor group detects in real time the inlet volume flow, inlet pressure, outlet pressure, speed, inlet temperature, and outlet temperature of the compressor. The collected operating parameters of the compressor are converted into digital signals through analog-to-digital conversion and transmitted to the controller.

[0011] Preferably, in step S2, the surge boundary line is generated by fitting with a surge boundary line fitting formula, which characterizes the corresponding relationship between the inlet volume flow and the pressure ratio. The surge boundary line fitting formula is: π surge =aQactual 2 +bQ actual +c, where π surge Q is the surge boundary pressure ratio. actual denoted as the inlet volumetric flow rate, and a, b, and c are fitting coefficients determined by fitting the compressor's factory performance data.

[0012] Preferably, in step S3, When the compressor is running in steady state, the controller sets the dynamic safety margin to the basic safety margin. The basic safety margin is the reference safety margin for the compressor's steady-state operation, with a value range of 5% to 8%. It is determined jointly by the compressor's factory performance data and the process characteristics of the MVR system and is pre-stored in the controller. When the rate of change of inlet volumetric flow rate or outlet pressure exceeds the preset threshold, the controller will adjust the dynamic safety margin to a high safety margin, with a value range of 10-15%. The preset threshold is the critical judgment value of the rate of change of inlet volumetric flow rate and outlet pressure, which is determined by the process fluctuation characteristics of the MVR system and the historical data of compressor operation stability, and is pre-stored in the controller. The high safety margin is jointly determined by the compressor's anti-disturbance capability and the system's safety protection requirements, and is also pre-stored in the controller. When the operating conditions return to stability and the duration reaches the preset stabilization time, the controller gradually reduces the dynamic safety margin at a fixed decay rate until it returns to the basic safety margin value. The preset stabilization time is the duration for determining the duration of the operating conditions returning to a steady state. It is determined by the process adjustment cycle of the MVR system and the dynamic response characteristics of the compressor and is stored in the controller.

[0013] Preferably, in step S4, the controller calculates the real-time operating pressure ratio of the compressor using the real-time operating pressure ratio calculation formula, calculates the anti-surge control line pressure ratio using the anti-surge control line calculation formula, and fits the anti-surge control line to obtain the anti-surge control line. The formula for calculating the real-time operating pressure ratio is: π actual =P out / P in , where π actual To achieve real-time operation of the pressure ratio, P out P is the compressor outlet pressure. in This refers to the compressor inlet pressure. The formula for calculating the anti-surge control line is: π control =π surge ×(1-SM), where π control To prevent surge, the control line voltage ratio is used; SM represents the dynamic safety margin; π surge The surge boundary pressure ratio.

[0014] Preferably, in step S5, the controller pre-stores a first warning threshold and a second warning threshold. Both thresholds are determined jointly by the compressor surge boundary characteristics and the system response speed, and the value of the second warning threshold is less than the first warning threshold. The controller calculates the distance between the real-time operating point and the anti-surge control line using the warning distance calculation formula: D=π control -π actual Where D is the distance between the real-time operating point and the anti-surge control line, and π actual To achieve real-time operating pressure ratio, π control To prevent surge, the controller controls the line voltage ratio. When the distance is greater than or equal to the first warning threshold, the controller does not output a warning signal and the anti-surge valve does not perform an opening action. When the distance is less than the first warning threshold, the controller outputs a low-level warning signal. When the distance is less than the second warning threshold and continues to decrease, the controller outputs a high-level warning signal and controls the anti-surge valve to open to a preset initial opening. The preset initial opening is a fixed opening value pre-stored by the controller and is determined by the compressor's minimum backflow characteristics.

[0015] Preferably, in step S5, after the controller determines that it has entered the anti-surge trigger state, it calculates the adjustment opening of the anti-surge valve using a proportional-derivative control algorithm, which is: ΔV=K p ×(π control -π actual )+K d ×d(π control -π actual ) / dt, where ΔV is the opening increment of the anti-surge valve, and K p K is the proportional adjustment coefficient. d K is the differential adjustment coefficient. p K d All were determined through on-site compressor characteristic tests, π actual To achieve real-time operating pressure ratio, π control To prevent surge, the line voltage ratio is controlled, where d is the differential operator and t is the time variable.

[0016] Preferably, in step S5, the anti-surge valve is set with a fixed maximum opening limit value, which is determined by the compressor inlet temperature protection limit value and the system reflux characteristics. When the valve opening reaches the maximum opening limit value and the operating condition has not left the danger zone, the controller outputs an emergency shutdown interlock command for the compressor.

[0017] The beneficial effects of the dynamic safety margin anti-surge control system and method for MVR steam compressors of the present invention are as follows: (1) This invention collects compressor operating parameters in real time and transmits them to the controller. The controller calculates the surge boundary line and dynamically adjusts the safety margin. It determines the safety margin value based on the stable state of the operating condition and the trend of parameter changes. Then, it generates the anti-surge control line for the corresponding operating condition by combining the surge boundary line. The dynamic matching control benchmark is built based on the real-time operating data. (2) By synchronously executing the early warning operation and pressure ratio comparison, the present invention ensures that the control logic always matches the real-time operating state of the compressor, and constructs an anti-surge control basic logic that is compatible with the operating characteristics of the MVR system. It can automatically adjust the control strategy according to the complex process changes of the MVR system, and has high adaptability and robustness to different operating conditions, achieving a balance between safety and efficiency, and expanding the stable operating range of the compressor. (3) This invention achieves proactive surge prevention by progressively linking graded early warning and anti-surge trigger control, relying on forward-looking adjustment. First, graded early warning and corresponding valve position actions are executed based on the distance between the operating point and the anti-surge control line. Then, after triggering the anti-surge state, the valve opening is determined by calculation and a smooth control action is executed to avoid secondary disturbances in the MVR evaporation system. Combined with the opening limit and emergency shutdown interlock, a complete protection link is formed to enhance the compressor's anti-interference capability. Based on the changing trend of operating parameters, prediction and early intervention are carried out, realizing the transformation from "passive response to surge" to "proactive prevention of surge", which significantly reduces the risk of surge and the mechanical impact on the unit. (4) This invention has strong adaptability to operating conditions through adaptive adjustment of dynamic safety margin, which can adapt to the complex process changes of MVR evaporation system. Under the premise of ensuring absolute safety, it maximizes the expansion of the stable working range of the compressor, improves operating efficiency, and reduces system energy consumption. Relying on the closed-loop collaboration of sensor group, controller, anti-surge valve and human-machine interface, it integrates early warning prediction, valve position adjustment, multi-level protection and manual intervention into a coherent execution system. Through the manual intervention interface, it can realize flexible switching between automatic control and manual regulation. Through the human-machine interface, it realizes status visualization, ensures the continuity and protection integrity of the entire anti-surge control process, and intuitively displays key information such as operating point, boundary line and safety margin through the human-machine interface, which greatly improves the convenience of system operation and the intuitiveness of maintenance. In summary, this invention achieves intelligent and adaptive anti-surge control by introducing a dynamic safety margin and predictive composite control strategy, thus solving the problems of difficulty in balancing safety and economy, poor adaptability, and lag in traditional anti-surge control. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the structure of an embodiment of the MVR steam compressor dynamic safety margin anti-surge control system of the present invention (in the figure, FI, PI, TI are the inlet flow rate, inlet pressure, and inlet temperature, PT, TT are the outlet pressure and outlet temperature, and SI is the compressor speed). Figure 2 This is a flowchart of an embodiment of the dynamic safety margin anti-surge control method for MVR steam compressors of the present invention; Figure 3 This is a flowchart illustrating the adaptive adjustment of the dynamic safety margin in an embodiment of the MVR steam compressor anti-surge control method of the present invention (SM in the figure). base Based on the basic safety margin, SM high For a high safety margin, T stable (Preset stabilization time); Figure 4 This is a schematic diagram of the compressor performance curve and anti-surge control principle in an embodiment of the MVR steam compressor dynamic safety margin anti-surge control method of the present invention; Figure 5 This is a flowchart illustrating the anti-surge control process in an embodiment of the dynamic safety margin anti-surge control method for MVR steam compressors of the present invention. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0020] Embodiment of the dynamic safety margin anti-surge control system for MVR steam compressor of the present invention: like Figure 1 As shown, the MVR steam compressor dynamic safety margin anti-surge control system includes: a sensor group, an anti-surge valve, a controller, and a human-machine interface; The sensor group includes a flow sensor, a pressure sensor, a temperature sensor, and a speed sensor, which detect the compressor's operating parameters in real time and transmit them to the controller. The anti-surge valve is a regulating valve, installed on the return pipeline from the compressor outlet to the inlet, and equipped with an opening feedback component. The opening feedback component transmits the real-time opening signal back to the controller, forming an opening closed-loop regulation circuit. The controller is electrically connected to the sensor group and the anti-surge valve respectively. The controller is a hardware module with data parsing, calculation and processing and instruction output. It can be a dedicated anti-surge controller or integrated into a distributed control system or a programmable logic controller. The human-machine interface is an interactive component that establishes an electrical connection with the controller. It displays the operating condition points, surge boundary line, anti-surge control line, dynamic safety margin, and early warning information in real time. The human-machine interface is also equipped with a manual intervention interface.

[0021] Example 1 of the dynamic safety margin anti-surge control method for MVR steam compressors of the present invention: like Figure 2 As shown, it includes the following steps: S1. Parameter Acquisition: In the continuous steady-state production scenario of MVR evaporation and concentration of saline wastewater in the chemical industry, the entire process is in a stable operating state with constant feed, stable evaporation, and continuous discharge. The steam compressor is not disturbed by external processes and always maintains a uniform and stable operating state. The chemical saline wastewater MVR evaporation system maintains a continuous and uninterrupted production state. The sensor group equipped with the steam compressor continuously collects the compressor's inlet volumetric flow rate, inlet pressure, outlet pressure, speed, inlet temperature, and outlet temperature. After analog-to-digital conversion, all collected operating parameters are stably transmitted to the controller in the form of digital signals, providing complete, accurate, and continuous raw data support. This ensures the accuracy and reliability of the entire anti-surge control process from the data acquisition source.

[0022] S2. Boundary Calculation: After receiving all operating parameters transmitted by the sensor group, the controller calculates the surge boundary line corresponding to the current speed in real time based on the design performance data of the steam compressor, using the surge boundary line fitting formula. The surge boundary line fitting formula is: π surge =aQ actual 2 +bQ actual +c, where π surge Q is the surge boundary pressure ratio. actual The inlet volumetric flow rate is represented by a, b, and c, which are fitting coefficients determined by fitting the compressor's factory performance data. The calculated surge boundary line data is stored in the controller's internal storage unit to ensure rapid retrieval later, allowing the generation of the anti-surge control benchmark to have accurate equipment performance basis and conform to the compressor's own operating characteristics.

[0023] S3. Safety Margin Adjustment: The controller comprehensively analyzes and determines the stable state of all received operating parameters, confirming that the compressor is in steady-state operation. The dynamic safety margin is set to a basic safety margin determined by the compressor's factory performance data and the MVR system's process characteristics. This basic safety margin is 6%. At this point, the rate of change of both the inlet volumetric flow rate and the outlet pressure does not exceed a preset threshold. The preset threshold is the critical judgment value for the rate of change of both the inlet volumetric flow rate and the outlet pressure, determined by the MVR system's process fluctuation characteristics and the compressor's historical operating stability data, and is pre-stored in the controller. If the standard deviation of any parameter exceeds the threshold, or if a feedforward disturbance signal is received from the process system, the system is determined to enter dynamic operating condition. The safety margin is immediately increased to a high safety margin of 12%. Upon entering dynamic operating condition, a timer is started. If the stable conditions are continuously met for a preset duration (120 seconds), the dynamic safety margin is gradually reduced at a fixed decay rate of 0.5% every 10 seconds until it returns to the basic safety margin value. Figure 3 As shown, after the controller completes the adaptive adjustment of the dynamic safety margin, it stores the data internally. By setting the safety margin to match the steady-state operating conditions, it enhances the compressor's anti-interference capability and enables precise matching between the compressor's operating state and the control logic.

[0024] S4. Control Line Generation: The controller calls the stored surge boundary line data and the adjusted dynamic safety margin data, and sequentially calculates the corresponding parameters using the real-time operating pressure ratio calculation formula and the anti-surge control line calculation formula to obtain the real-time operating pressure ratio and anti-surge control line under the current operating condition. The real-time operating pressure ratio calculation formula is: π actual =P out / P in , where π actual To achieve real-time operating pressure ratio, P out P is the compressor outlet pressure. in The compressor inlet pressure; its anti-surge control line calculation formula is: π control =π surge ×(1-SM), where π control To prevent surge, the control line voltage ratio is used; SM represents the dynamic safety margin; π surge The surge boundary pressure ratio is calculated; the two calculation results are simultaneously stored in the controller to form a dynamic anti-surge control benchmark that is fully adapted to the current steady-state operating conditions, providing a unified judgment standard for subsequent early warning and prevention operations.

[0025] S5. Prevention and Control Execution: The controller pre-stores a first warning threshold and a second warning threshold. Both thresholds are determined jointly by the compressor surge boundary characteristics and the system response speed. The first warning threshold is set to 5% × π. surge The second warning threshold is set at 2% × π surgeThe second warning threshold value is less than the first warning threshold; the controller calls the anti-surge control line and real-time operating pressure ratio data, and calculates the distance between the operating point and the anti-surge control line using the warning distance calculation formula: D=π control -π actual Where D is the distance between the real-time operating point and the anti-surge control line, and π actual To achieve real-time operating pressure ratio, π control To prevent surge, control the line voltage ratio; such as Figure 4 As shown, the judgment interval is greater than or equal to 5% × π of the first warning threshold. surge It does not output any warning signals and the anti-surge valve does not perform any opening action. At the same time, it continuously compares the real-time operating pressure ratio with the anti-surge control line to confirm that the real-time operating pressure ratio has not reached the anti-surge trigger condition. In addition, the anti-surge valve is set with a fixed maximum opening limit of 70%. This maximum opening limit is determined by the compressor inlet temperature protection limit and the system reflux characteristics. It is used to prevent excessive reflux from causing the compressor inlet temperature to be too high. The compressor continues to maintain a stable operating state. The entire control process achieves disturbance-free steady-state protection and effectively ensures that the MVR evaporation system can continuously and stably complete the salt wastewater concentration operation.

[0026] In summary, for the steady-state production scenario of MVR evaporation and concentration of chemical saline wastewater, the system relies on a sensor array to collect and transmit operational data, perform boundary calculations, and adaptively set safety margins based on operating conditions. This generates a control benchmark suitable for steady-state operation. Through graded early warning judgment and continuous prevention and control comparison, the system achieves stable protection without disturbance throughout the process, keeping the steam compressor in a stable operating state. This provides reliable anti-surge protection for the continuous steady-state production of the MVR evaporation system, ensuring the continuous and stable progress of the production process.

[0027] Example 2 of the dynamic safety margin anti-surge control method for MVR steam compressors of the present invention: like Figure 2 As shown, it includes the following steps: S1. Parameter Acquisition: In the process disturbance and variable operating condition scenario of the MVR evaporation system for syrup concentration in the food processing industry, the feed concentration and feed flow rate may suddenly fluctuate due to the adjustment of the production formula. The operating condition of the steam compressor changes rapidly and is in a non-steady-state disturbance operating state. Due to the sudden change in feed parameters caused by the adjustment of the production process, the sensor group equipped with the steam compressor collects the compressor's inlet volumetric flow rate, inlet pressure, outlet pressure, speed, inlet temperature and outlet temperature in real time. After the collected operating parameters are processed by analog-to-digital conversion, they are continuously transmitted to the controller in the form of digital signals. This quickly captures all the core data of the operating condition change, providing real-time, comprehensive and synchronous data support for dynamic anti-surge control, ensuring that the control action can keep up with the rhythm of the operating condition change and make a rapid response.

[0028] S2. Boundary Calculation: After receiving all operating parameters transmitted by the sensor group, the controller calculates the surge boundary line corresponding to the current speed in real time based on the design performance data of the steam compressor, using the surge boundary line fitting formula. The surge boundary line fitting formula is: π surge =aQ actual 2 +bQ actual +c; Store the calculated surge boundary line data into the controller's internal storage unit, quickly update the core boundary data to adapt to rapidly changing control requirements, ensure the real-time performance and accuracy of the anti-surge control benchmark, and prevent deviations from actual operating conditions.

[0029] S3. Margin Adjustment: The controller has a preset threshold, which is the critical judgment value between the rate of change of inlet volumetric flow rate and the rate of change of outlet pressure. It is determined by the process fluctuation characteristics of the MVR system and historical data on compressor operating stability. The controller performs comprehensive analysis and stability judgment on all received operating parameters, continuously calculates the standard deviation of inlet volumetric flow rate and real-time operating pressure ratio within the most recent 30 seconds. If the standard deviation of any parameter exceeds the steady-state threshold, or if a feedforward disturbance signal from the process system is received, such as a large movement of the evaporator feed valve, the controller determines that the compressor has entered a rapidly changing operating mode and dynamically adjusts the control mechanism. The full margin adjustment is a high safety margin determined jointly by the compressor's disturbance rejection capability and system safety protection requirements. The high safety margin is 12%, and data is stored. After the subsequent operating conditions return to stability and the duration reaches the preset stabilization time, the controller gradually reduces the dynamic safety margin at a fixed decay rate of 0.5% every 10 seconds until it returns to the basic safety margin, which is 6%. The preset stabilization time is the duration for determining the steady state of the operating conditions, which is 120 seconds. This time is determined by the MVR system's process adjustment cycle and the compressor's dynamic response characteristics and is pre-stored in the controller. Figure 3 As shown, by increasing the safety margin to reserve sufficient protective buffer space for the compressor, the equipment's ability to resist process disturbances is greatly enhanced.

[0030] S4. Control Line Generation: The controller calls the stored surge boundary line data and adjusted high-level safety margin data, and completes parameter calculations using the real-time operating pressure ratio calculation formula and the anti-surge control line calculation formula. It generates and stores the real-time operating pressure ratio and anti-surge control line adapted to the current variable operating conditions, quickly constructing a dynamic control benchmark that fits the current disturbance conditions. This ensures that the early warning and prevention judgment criteria always match the real-time operating status. The real-time operating pressure ratio calculation formula is: π actual =P out / P in The formula for calculating the anti-surge control line is: π control =π surge×(1-SM).

[0031] S5. Prevention and Control Execution: The controller pre-stores a first warning threshold and a second warning threshold. Both thresholds are determined jointly by the compressor surge boundary characteristics and the system response speed. The first warning threshold is set to 5% × π. surge The second warning threshold is set at 2% × π surge The second warning threshold value is less than the first warning threshold; the controller calls the anti-surge control line and real-time operating pressure ratio data, and calculates the distance between the operating point and the anti-surge control line using the warning distance calculation formula: D=π control -π actual ;like Figure 4 As shown, the system first determines that the spacing is less than the first warning threshold and outputs a low-level warning signal. Based on the reserved manual intervention interface, the control mode can be switched and intervention can be carried out according to the actual situation. When the spacing is subsequently detected to be continuously decreasing and less than the second warning threshold, a high-level warning signal is output and the anti-surge valve is controlled to open at a preset initial opening degree determined by the minimum backflow characteristics of the compressor. After continuous comparison, it is determined that the real-time operating pressure ratio has reached the anti-surge trigger condition. Figure 5 As shown, the system immediately enters the anti-surge trigger state. The proportional-derivative control algorithm calculates the anti-surge valve opening and controls the valve's smooth operation to avoid secondary disturbances to the MVR evaporation system. The proportional-derivative control algorithm is: ΔV = K p ×(π control -π actual )+K d ×d(π control -π actual ) / dt, where ΔV is the opening increment of the anti-surge valve, and K p K is the proportional adjustment coefficient. d K is the differential adjustment coefficient. p K d All were determined through on-site compressor characteristic tests, π actual To achieve real-time operating pressure ratio, π control To prevent surge, the control line voltage ratio is set, where d is the differential operator and t is the time variable. Simultaneously, the compressor speed is reduced, and the valve opening is monitored in real time during operation. The anti-surge valve has a fixed maximum opening limit of 70%, determined by the compressor inlet temperature protection limit and the system reflux characteristics. When the valve opening reaches the maximum limit and the operating condition is not out of the danger zone, the controller outputs an emergency compressor stop interlock command to quickly pull the compressor back to a safe operating range. These operations fully realize progressive anti-surge protection under varying operating conditions, forming a complete protection chain from early warning and prediction to proactive control, effectively avoiding the adverse effects of surge faults on the compressor equipment and the syrup concentration production process.

[0032] In summary, for MVR evaporation systems used for food syrup concentration under varying operating conditions, this system collects and transmits operational data and performs boundary calculations in real time. It dynamically adjusts the safety margin based on operating condition fluctuations, generates control benchmarks adapted to the disturbance conditions, and sequentially executes tiered early warning and progressive prevention and control actions. Combined with valve position adjustment and speed control, it achieves full-process protection, quickly restoring the steam compressor to a safe operating range. This constructs a complete and coherent anti-surge protection system, effectively mitigating equipment operation risks caused by operating condition fluctuations.

Claims

1. A dynamic safety margin anti-surge control system for an MVR steam compressor, characterized in that, include: Sensor assembly, anti-surge valve, and controller; The sensor group includes a flow sensor, a pressure sensor, a temperature sensor, and a speed sensor, which detect the compressor's operating parameters in real time and transmit them to the controller. The anti-surge valve is installed on the return pipeline from the compressor outlet to the inlet, and is equipped with an opening feedback component. The opening feedback component transmits the real-time opening signal back to the controller, forming an opening closed-loop regulation circuit. The controller is electrically connected to the sensor group and the anti-surge valve, and the controller is a hardware module with data parsing, calculation and processing and instruction output.

2. The MVR steam compressor dynamic safety margin anti-surge control system according to claim 1, characterized in that, Also includes: Human-machine interface; the human-machine interface is an interactive component that establishes an electrical connection with the controller, and displays the operating condition point, surge boundary line, anti-surge control line, dynamic safety margin and early warning information in real time, and the human-machine interface is equipped with a manual intervention interface.

3. A dynamic safety margin anti-surge control method for an MVR steam compressor applicable to the system described in claim 1 or 2, characterized in that, Includes the following steps: S1. Parameter Acquisition: Real-time acquisition of compressor operating parameters to determine real-time operating condition point, and transmission of the acquired operating parameters to the controller in the form of digital signals; S2, Boundary Calculation: After receiving the compressor's operating parameters, the controller calculates the surge boundary line at the current speed in real time based on the compressor's design performance data, and stores the surge boundary line data in the controller. S3, Margin Adjustment: After receiving the compressor's operating parameters, the controller sets a dynamic safety margin and adaptively adjusts it according to the compressor's stable operating condition and the trend of operating parameter changes. The adjusted dynamic safety margin data is then stored in the controller. S4. Control line generation: The controller calls the surge boundary line data and the adjusted dynamic safety margin data to calculate the anti-surge control line and the real-time operating pressure ratio of the compressor under the current operating conditions, and then stores the calculation results in the controller. S5. Prevention and Control Execution: The controller calls the anti-surge control line data and the compressor's real-time operating pressure ratio data. First, it calculates the distance between the real-time operating point and the anti-surge control line and executes an early warning operation. At the same time, it continuously compares the real-time operating pressure ratio with the anti-surge control line. When the real-time operating pressure ratio is greater than or equal to the anti-surge control line, the controller determines that it has entered the anti-surge trigger state, outputs the anti-surge control action signal, calculates the adjustment opening of the anti-surge valve and controls the anti-surge valve to act, and at the same time reduces the compressor speed to perform anti-surge control.

4. The dynamic safety margin anti-surge control method for MVR steam compressors according to claim 3, characterized in that, In step S1, the compressor's operating parameters are collected by the sensor group that is equipped with the compressor. The sensor group detects the compressor's inlet volume flow rate, inlet pressure, outlet pressure, speed, inlet temperature and outlet temperature in real time. The collected compressor operating parameters are converted from analog to digital and then transmitted to the controller as digital signals.

5. The dynamic safety margin anti-surge control method for MVR steam compressors according to claim 3 or 4, characterized in that, In step S2, the surge boundary line is generated by fitting a surge boundary line fitting formula, which characterizes the relationship between the inlet volumetric flow rate and the pressure ratio. The surge boundary line fitting formula is: π surge =aQ actual 2 +bQ actual +c, where π surge Q is the surge boundary pressure ratio. actual denoted as the inlet volumetric flow rate, and a, b, and c are fitting coefficients determined by fitting the compressor's factory performance data.

6. The dynamic safety margin anti-surge control method for MVR steam compressors according to any one of claims 3 to 5, characterized in that, In step S3, When the compressor is running in steady state, the controller sets the dynamic safety margin to the basic safety margin. The basic safety margin is the reference safety margin for the compressor's steady-state operation, with a value range of 5% to 8%. It is determined jointly by the compressor's factory performance data and the process characteristics of the MVR system and is pre-stored in the controller. When the rate of change of inlet volumetric flow rate or outlet pressure exceeds a preset threshold, the controller will adjust the dynamic safety margin to a high safety margin, with a value range of 10% to 15%. The preset threshold is the critical judgment value of the rate of change of inlet volume flow rate and the rate of change of outlet pressure. It is determined by the process fluctuation characteristics of the MVR system and the historical data of compressor operation stability, and is pre-stored in the controller. The high safety margin is jointly determined by the compressor's anti-disturbance capability and the system's safety protection requirements, and is also pre-stored in the controller. When the operating conditions return to stability and the duration reaches the preset stabilization time, the controller gradually reduces the dynamic safety margin at a fixed decay rate until it returns to the basic safety margin value. The preset stabilization time is the duration for determining the duration of the operating conditions returning to a steady state. It is determined by the process adjustment cycle of the MVR system and the dynamic response characteristics of the compressor and is stored in the controller.

7. The dynamic safety margin anti-surge control method for MVR steam compressors according to any one of claims 3 to 6, characterized in that, In step S4, the controller calculates the real-time operating pressure ratio of the compressor using the real-time operating pressure ratio calculation formula, calculates the anti-surge control line pressure ratio using the anti-surge control line calculation formula, and fits the anti-surge control line to obtain the anti-surge control line. The formula for calculating the real-time operating pressure ratio is: π actual =P out / P in , where π actual To achieve real-time operation of the pressure ratio, P out P is the compressor outlet pressure. in This refers to the compressor inlet pressure. The formula for calculating the anti-surge control line is: π control =π surge ×(1-SM), where π control To prevent surge, the control line voltage ratio is used; SM represents the dynamic safety margin; π surge The surge boundary pressure ratio.

8. The dynamic safety margin anti-surge control method for MVR steam compressors according to any one of claims 3 to 7, characterized in that, In step S5, the controller pre-stores a first warning threshold and a second warning threshold. Both types of thresholds are determined by the compressor surge boundary characteristics and the system response speed. The value of the second warning threshold is less than that of the first warning threshold. The controller calculates the distance between the real-time operating point and the anti-surge control line using the early warning distance calculation formula: D = π control -π actual Where D is the distance between the real-time operating point and the anti-surge control line, and π actual To achieve real-time operating pressure ratio, π control To prevent surge, the control line voltage ratio is adjusted. When the distance is greater than or equal to the first warning threshold, the controller does not output a warning signal and the anti-surge valve does not open. When the distance is less than the first warning threshold, the controller outputs a low-level warning signal. When the distance is less than the second warning threshold and continues to decrease, the controller outputs an advanced warning signal and controls the anti-surge valve to open to a preset initial opening degree. The preset initial opening degree is a fixed opening degree value stored in the controller and is determined by the compressor's minimum backflow flow characteristics.

9. The dynamic safety margin anti-surge control method for MVR steam compressors according to any one of claims 3 to 8, characterized in that, In step S5, after the controller determines that it has entered the anti-surge trigger state, it calculates the adjustment opening of the anti-surge valve using a proportional-derivative control algorithm. The proportional-derivative control algorithm is: ΔV=K p ×(π control -π actual )+K d ×d(π control -π actual ) / dt, where ΔV is the opening increment of the anti-surge valve, and K p K is the proportional adjustment coefficient. d K is the differential adjustment coefficient. p K d All were determined through on-site compressor characteristic tests, π actual To achieve real-time operating pressure ratio, π control To prevent surge, the line voltage ratio is controlled, where d is the differential operator and t is the time variable.

10. The dynamic safety margin anti-surge control method for MVR steam compressors according to any one of claims 3 to 9, characterized in that, In step S5, the anti-surge valve is set with a fixed maximum opening limit value, which is determined by the compressor inlet temperature protection limit and the system backflow characteristics. When the valve opening reaches the maximum opening limit value and the operating conditions have not left the danger zone, the controller outputs an emergency shutdown interlock command for the compressor.

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