A sulfuric acid feedstock stable delivery system and method

Abstract

The present application relates to sulfuric acid raw material conveying control technical field, disclose a kind of sulfuric acid raw material feeding stable conveying system and method, comprising: flow detection unit acquires the real-time flow data of conveying pipeline, wall temperature acquisition unit acquires the pipeline wall temperature data of heat tracing pipe section, adjusting control unit is calculated and exported drive frequency control instruction according to flow resistance inversion tendency, temperature space dispersion and transmission mechanical gap parameter, drive frequency control unit adjusts the output power of pumping mechanism according to drive frequency control instruction, the control gain of feedback loop is adjusted by the present application, the adjustment phase lag caused by sulfuric acid raw material crystallization and flow resistance nonlinear mutation is suppressed, the mechanical freedom degradation caused by transmission bearing wear is overcome, and the steady-state linearization high-precision convergence of feed flow is realized.

Description

Technical Field

[0001] This invention belongs to the field of sulfuric acid raw material conveying and control technology, and particularly relates to a stable conveying system and method for sulfuric acid raw material feeding. Background Technology

[0002] Current traditional solutions employ a closed-loop control system composed of a flow sensor and a frequency converter to maintain a stable feed flow rate. The frequency converter collects timing data from the flow sensor at the end of the pipeline and adjusts the output parameters of the electric drive frequency in real time to control the conveying power of the pumping mechanism. When handling liquid media with constant viscosity and simple composition, the control loop response lag remains within the allowable accuracy range, which is a common method in the industry. However, when the system is used to handle high-concentration sulfuric acid raw materials with high crystallization tendency and strong corrosiveness, it suffers from control instability. High-concentration sulfuric acid has thermosensitive crystallization physicochemical properties, and its... The viscous resistance of the flow undergoes a drastic nonlinear transition due to a decrease in local temperature or a sudden fluctuation in concentration. The sudden change in mass transfer impedance inside the pipeline directly affects the controlled feed, causing the pressure resistance wave inside the system to spread rapidly. Traditional control loops rely solely on the fact that the apparent flow rate deviates from the target value as a feedback source. The signal acquisition process has an unavoidable time phase lag. Before the controller can output an effective correction command, the change in medium flow resistance has already caused obvious flow pulsation, and may even lead to transient overpressure in the pipeline. Transient overpressure causes mechanical wear of valves or creates the risk of downstream material reaction ratio imbalance.

[0003] To mitigate the time-delay overshoot problem in the aforementioned control loop, industry practice typically involves using an external high-power heating jacket to maintain a constant temperature on the pipeline wall. Alternatively, the proportional gain constant of the controller can be linearly increased to accelerate the closed-loop response. However, external heating jackets cannot block the localized flow resistance backflow waves caused by frequent opening and closing of upstream process valves. Furthermore, increasing the feedback gain of the control loop amplifies electromagnetic noise and discrete numerical calculation errors within a fixed discrete sampling period, leading to high-frequency divergence in the control frequency command. This causes severe vibration of the conveying mechanism, resulting in integral saturation divergence failure of the controller. Hardware improvements such as external heating jackets cannot suppress sudden changes in fluid properties. The system instability caused by the change also presents technical bottlenecks at the control strategy level. For example, Chinese invention patent with authorization announcement number CN210171460U discloses a device for DCS-controlled multi-step regeneration of concentrated sulfuric acid and automatic acid addition. It combines the control system to collect flow and concentration signals to match the preset regeneration curve. However, the underlying logic is highly dependent on the static process curve under ideal flow conditions and conventional deviation feedback adjustment. When faced with the nonlinear crystallization process caused by local temperature fluctuations in the pipeline, the hysteresis response mechanism cannot reversely decouple the transient evolution of mass transfer impedance, cannot perform feedforward power compensation before the actual flow drop, is difficult to eliminate the phase delay of the adjustment loop, and is prone to loop integral saturation divergence when faced with transient pressure impacts in the flow field.

[0004] Therefore, the technical problem to be solved by this invention is how to use the native data of the controlled loop to decouple the fluid mass transfer impedance transition characteristics in reverse and complete the internal matrix calibration before the flow deviation occurs, thereby completing the adaptive in-situ calibration of the parameters of the adjustment gain matrix. Summary of the Invention

[0005] The present invention aims to solve the problem of using native data of controlled loops to decouple the fluid mass transfer impedance transition characteristics in reverse and to complete the internal matrix calibration before the flow deviation occurs, thereby achieving the adaptive in-situ calibration of the parameters of the adjustment gain matrix.

[0006] In this technical solution, a stable conveying system for sulfuric acid feedstock includes: The flow detection unit is used to collect real-time flow data of the delivery pipeline; The wall temperature acquisition unit is used to collect the pipe wall temperature data of the heat tracing pipe section; The regulating control unit connects the flow detection unit and the wall temperature acquisition unit. It is used to calculate and output drive frequency control commands based on real-time flow data and pipeline wall temperature data. The regulating control unit includes a flow resistance inversion section, a filter regulation section, and a transmission hysteresis compensation section. The flow resistance inversion section is used to compare the frequency command increment with the flow rate change rate to determine the trend of fluid mass transfer flow resistance. The filter adjustment section is used to calculate the temperature spatial dispersion based on the pipe wall temperature data, and when the temperature spatial dispersion is greater than the preset crystallization temperature threshold, the cutoff frequency of the low-pass filter parameter is reduced, and the proportional gain constant is increased according to the time downward trend of the pipe wall temperature data. The transmission lag compensation section is used to calculate the transmission mechanical clearance parameters when the response delay time between the drive frequency control command and the real-time flow data increases monotonically, and to superimpose a stepped frequency jump when outputting the drive frequency control command. The drive frequency control unit, connected to the adjustment control unit, is used to adjust the output power of the pumping mechanism according to the drive frequency control command.

[0007] Preferably, the regulating control unit also includes an integral suspension module, which suspends the integral accumulation of the regulating loop when a transient pressure shock occurs in the delivery pipeline, and completes steady-state deviation correction of the control loop according to the anti-saturation correction coefficient.

[0008] Preferably, the adjustment and control unit includes a temperature sampling cluster for multi-point settlement of pipeline wall temperature data; the temperature sampling cluster is arranged on multiple symmetrical temperature measurement points in the heat tracing pipe section to obtain real-time wall temperature, and the adjustment and control unit calculates the wall temperature variance between multiple symmetrical temperature measurement points, and uses the wall temperature variance as the temperature spatial dispersion.

[0009] Preferably, when determining the trend of change, the control unit separates the flow response phase lag and adjusts the incremental direction of the drive frequency control command to be monotonically opposite to the transient rate of change of the real-time flow data.

[0010] Preferably, the control unit records the response delay time of the drive frequency control command and real-time flow data, and when the response delay time monotonically increases with the cumulative running time, the rate of increase is used as the bearing wear index of the pumping mechanism, and a maintenance warning signal is output to the external system when the bearing wear index reaches a preset safety threshold.

[0011] Preferably, the cutoff frequency of the low-pass filter parameter is adjusted within the range of 0.1Hz to 5.0Hz; when the temperature space dispersion is not greater than the crystallization temperature threshold, the cutoff frequency is 4.5Hz; when the temperature space dispersion is greater than the crystallization temperature threshold, the control unit adjusts the cutoff frequency to 0.5Hz.

[0012] Preferably, the crystallization temperature threshold is pre-calibrated based on the crystallization characteristic curve of sulfuric acid at different ambient temperatures; the control unit uses the point of change in the cooling rate in the pipeline wall temperature data as the trigger limit of the crystallization temperature threshold.

[0013] Preferably, the adjustment control unit includes a transient distortion calibration sub-section for suppressing sudden abnormal interference flow resistance; the transient distortion calibration sub-section calculates the second-order difference between the feedback current data of the drive frequency control unit in the current control cycle and the values ​​of the two adjacent historical control cycles to generate a current distortion slope variable, and performs in-situ correction of the proportional gain constant of the flow deviation based on the current distortion slope variable and the rate of change of the temperature spatial dispersion.

[0014] Preferably, it also includes a safety pressure relief and return unit and a flushing unit connected to the delivery pipeline; when the integral suspension module suspends the integral accumulation of the adjustment circuit and the delivery pipeline is completely blocked, the safety pressure relief and return unit opens the safety return valve, limits the maximum output power of the proportional gain constant, and drives the flushing unit to inject alkali into the delivery pipeline.

[0015] A method for stabilizing the feeding and conveying of sulfuric acid feedstock, used to operate a sulfuric acid feedstock stabilizing and conveying system, comprising: Step S1: Collect real-time flow data of the delivery pipeline through the flow detection unit; Step S2: Collect pipe wall temperature data of the heat tracing pipe section through the wall temperature acquisition unit; Step S3: The control unit calculates and outputs a drive frequency control command based on real-time flow data and pipe wall temperature data. Step S4: The output power of the pumping mechanism is adjusted by the drive frequency control unit according to the drive frequency control command; wherein, the control unit calculates and outputs the drive frequency control command based on real-time flow data and pipeline wall temperature data. Step S5: By comparing the frequency command increment with the flow rate change rate in the flow resistance inversion section, the variation trend of fluid mass transfer flow resistance is determined. Step S6: The temperature spatial dispersion is calculated based on the pipe wall temperature data by the filtering adjustment section. When the temperature spatial dispersion is greater than the preset crystallization temperature threshold, the cutoff frequency of the low-pass filter parameter is reduced, and the proportional gain constant is increased according to the downward trend of the pipe wall temperature data over time. Step S7: Through the transmission lag compensation part, when the response delay time between the drive frequency control command and the real-time flow data increases monotonically, the transmission mechanical clearance parameter is calculated, and a step-like frequency jump is superimposed when the drive frequency control command is output.

[0016] Compared with existing technologies, the sulfuric acid raw material stable conveying system of the present invention has the following advantages: 1. In the stable feeding and conveying of sulfuric acid raw materials, the sliding window decoupling calculation is completed by adjusting the control unit to the feedback current sequence of the drive end and the static pressure parameters of the pipeline outlet. The influence of the static pressure transition in the pipeline is removed, and the current distortion characteristic value reflecting the intrinsic dynamic viscosity change of the medium is extracted. Based on this characteristic value, the in-situ nonlinear correction is applied to the flow deviation feedback adjustment gain term, so that the control loop parameters adapt to the evolution of material flow resistance. Under the condition of reducing the dependence on external sensors, the dependence of conventional feedback control on the terminal apparent flow drop is eliminated, and the adjustment phase lag caused by the sudden change in fluid viscosity is smoothed out, so as to achieve high-precision convergence of dynamic linearization of feed flow deviation under the entire flow range.

[0017] 2. By adjusting the built-in adaptive first-order low-pass dynamic filter matrix of the control unit, the cutoff frequency is kept monotonically positively correlated with the real-time flow data. High-frequency noise band interception is carried out on the current distortion slope variable of the differential calculation output to weaken the amplification effect of high-frequency numerical noise. Combined with the logic rack bounce compensation factor, dynamic bandwidth limitation is applied to the feedback adjustment gain term to forcibly control the maximum adjustment amplitude of a single step to not exceed 10% of the output value of the previous cycle. This avoids the instruction divergence defect caused by large-scale pulsation in multi-dimensional operating conditions. While ensuring the safe and stable operation of the controller, it also properly blocks the loop integral saturation divergence caused by channel obstruction.

[0018] 3. By collecting local temperature characteristic parameters of the pipe wall in the weak section of the heated pipe through the raw material crystallization monitoring node, the temperature spatial dispersion is obtained by the adjustment and control unit. When the temperature spatial dispersion crosses the preset critical crystallization barrier threshold, the cutoff frequency of the adaptive first-order low-pass dynamic filter matrix is ​​lowered in advance to shield the spike current noise caused by the initial stage of crystal nucleus agglomeration from the source. At the same time, according to the monotonically downward trend of temperature over time, the proportional gain constant in the feedback adjustment gain term is increased in advance to complete the feedforward power compensation of the electric drive frequency before the flow velocity deviates substantially, thereby changing the dynamic control response of the system to deal with local thermal drift and crystallization resistance accumulation. Attached Figure Description

[0019] Figure 1 This is a flowchart of the control steps of a stable feeding and conveying method for sulfuric acid raw materials according to the present invention; Figure 2 This is a hardware node structure diagram of a stable sulfuric acid feed conveying system according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0021] A stable conveying system for sulfuric acid feedstock includes: The flow detection unit is used to collect real-time flow data of the delivery pipeline; The wall temperature acquisition unit is used to collect the pipe wall temperature data of the heat tracing pipe section; The regulating control unit connects the flow detection unit and the wall temperature acquisition unit. It is used to calculate and output drive frequency control commands based on real-time flow data and pipeline wall temperature data. The regulating control unit includes a flow resistance inversion section, a filter regulation section, and a transmission hysteresis compensation section. The flow resistance inversion section is used to compare the frequency command increment with the flow rate change rate to determine the trend of fluid mass transfer flow resistance. The filter adjustment section is used to calculate the temperature spatial dispersion based on the pipe wall temperature data, and when the temperature spatial dispersion is greater than the preset crystallization temperature threshold, the cutoff frequency of the low-pass filter parameter is reduced, and the proportional gain constant is increased according to the time downward trend of the pipe wall temperature data. The transmission lag compensation section is used to calculate the transmission mechanical clearance parameters when the response delay time between the drive frequency control command and the real-time flow data increases monotonically, and to superimpose a stepped frequency jump when outputting the drive frequency control command. The drive frequency control unit, connected to the adjustment control unit, is used to adjust the output power of the pumping mechanism according to the drive frequency control command.

[0022] Preferably, the regulating control unit also includes an integral suspension module, which suspends the integral accumulation of the regulating loop when a transient pressure shock occurs in the delivery pipeline, and completes steady-state deviation correction of the control loop according to the anti-saturation correction coefficient.

[0023] Preferably, the adjustment and control unit includes a temperature sampling cluster for multi-point settlement of pipeline wall temperature data; the temperature sampling cluster is arranged on multiple symmetrical temperature measurement points in the heat tracing pipe section to obtain real-time wall temperature, and the adjustment and control unit calculates the wall temperature variance between multiple symmetrical temperature measurement points, and uses the wall temperature variance as the temperature spatial dispersion.

[0024] Preferably, when determining the trend of change, the control unit separates the flow response phase lag and adjusts the incremental direction of the drive frequency control command to be monotonically opposite to the transient rate of change of the real-time flow data.

[0025] Preferably, the control unit records the response delay time of the drive frequency control command and real-time flow data, and when the response delay time monotonically increases with the cumulative running time, the rate of increase is used as the bearing wear index of the pumping mechanism, and a maintenance warning signal is output to the external system when the bearing wear index reaches a preset safety threshold.

[0026] Preferably, the cutoff frequency of the low-pass filter parameter is adjusted within the range of 0.1Hz to 5.0Hz; when the temperature space dispersion is not greater than the crystallization temperature threshold, the cutoff frequency is 4.5Hz; when the temperature space dispersion is greater than the crystallization temperature threshold, the control unit adjusts the cutoff frequency to 0.5Hz.

[0027] Preferably, the crystallization temperature threshold is pre-calibrated based on the crystallization characteristic curve of sulfuric acid at different ambient temperatures; the control unit uses the point of change in the cooling rate in the pipeline wall temperature data as the trigger limit of the crystallization temperature threshold.

[0028] Preferably, the adjustment control unit includes a transient distortion calibration sub-section for suppressing sudden abnormal interference flow resistance; the transient distortion calibration sub-section calculates the second-order difference between the feedback current data of the drive frequency control unit in the current control cycle and the values ​​of the two adjacent historical control cycles to generate a current distortion slope variable, and performs in-situ correction of the proportional gain constant of the flow deviation based on the current distortion slope variable and the rate of change of the temperature spatial dispersion.

[0029] Preferably, it also includes a safety pressure relief and return unit and a flushing unit connected to the delivery pipeline; when the integral suspension module suspends the integral accumulation of the adjustment circuit and the delivery pipeline is completely blocked, the safety pressure relief and return unit opens the safety return valve, limits the maximum output power of the proportional gain constant, and drives the flushing unit to inject alkali into the delivery pipeline.

[0030] A method for stable feeding and conveying of sulfuric acid feedstock includes: Step S1: Collect real-time flow data of the delivery pipeline through the flow detection unit; Step S2: Collect pipe wall temperature data of the heat tracing pipe section through the wall temperature acquisition unit; Step S3: The control unit calculates and outputs a drive frequency control command based on real-time flow data and pipe wall temperature data. Step S4: The output power of the pumping mechanism is adjusted by the drive frequency control unit according to the drive frequency control command; wherein, the control unit calculates and outputs the drive frequency control command based on real-time flow data and pipeline wall temperature data. Step S5: By comparing the frequency command increment with the flow rate change rate in the flow resistance inversion section, the variation trend of fluid mass transfer flow resistance is determined. Step S6: The temperature spatial dispersion is calculated based on the pipe wall temperature data by the filtering adjustment section. When the temperature spatial dispersion is greater than the preset crystallization temperature threshold, the cutoff frequency of the low-pass filter parameter is reduced, and the proportional gain constant is increased according to the downward trend of the pipe wall temperature data over time. Step S7: Through the transmission lag compensation part, when the response delay time between the drive frequency control command and the real-time flow data increases monotonically, the transmission mechanical clearance parameter is calculated, and a step-like frequency jump is superimposed when the drive frequency control command is output.

[0031] Example 1: When the system faces uneven heating and alternating pressure conditions, and the sulfuric acid raw material inside the delivery pipeline experiences local dynamic viscosity changes due to fluctuations in external ambient temperature, as well as transient pressure backflow caused by the opening and closing of downstream batching valves, the flow detection unit collects real-time flow data from the delivery pipeline and sends it to the regulating control unit. Conventional control loops rely on the deviation between the real-time flow data and the set threshold as the basis for adjustment. This deviation accumulates after changes in flow resistance, causing the drive frequency control unit to receive commands at a time lag behind the moment of abrupt change in mass transfer flow resistance. This amplifies electromagnetic ambient noise and numerical calculation errors within the discrete sampling period, leading to control loop oscillation and integral saturation divergence. To eliminate the phase lag in the control loop caused by abrupt changes in flow resistance, the flow detection unit sends the collected real-time flow data to the regulating control unit. The flow resistance inversion part inside the regulating control unit synchronously acquires the frequency command increment within a 10ms timing control period. With real-time flow change rate In the calculation process, to compensate for the response phase difference caused by the rotational inertia of the pump hub, the flow resistance inversion part obtains... A timing advance compensation was performed to align it with the time axis reflecting the flow field response. Alignment, through this discrete-domain time alignment process, simplifies the complex dynamic impedance into a quasi-static flow impedance representation vector, thereby enabling the tracking of the medium viscosity trend via frequency command increments. With real-time flow change rate Calculating the ratio of discrete flow impedance characterization vectors Hagen-Poiseuille's law states that the flow rate of a viscous fluid in a pipeline is directly proportional to the pressure difference between the two ends and inversely proportional to the fluid's dynamic viscosity. The frequency increment of the pumping mechanism... Linearly correlated with changes in input pressure differential, instantaneous flow rate variation Characterizing the kinetic energy response velocity of the flow field, the control unit uses frequency command increments. With real-time flow change rate Discrete domain ratios are used to invert the fluid mass transfer impedance trend, and the control unit is adjusted using the formula. In-situ corrected flow deviation proportional gain constant ,in, The corrected proportional gain constant ranges from 1.5 to 12.0. It is a dimensionless proportional gain reference constant, determined by the initial steady-state calibration of the system; The second-order difference value of the feedback current data. This represents the rate of change of the spatial dispersion of temperature. This is the current distortion correction factor, with a value ranging from 0.05 to 0.15; The temperature compensation factor, ranging from 0.2 to 0.4, is used to adjust the control unit. The measured variables of the current control cycle are substituted into the formula to determine the dynamic adjustment of the proportional gain. This is done when the discrete flow impedance characterization vector... When the flow resistance exceeds the first safety range and increases monotonically, the proportional gain constant in the control loop is increased in the flow resistance inversion section to enhance the control output in the forward feedback stage and intercept the deviation of the pipeline flow rate. The flow resistance inversion section calculates the discrete flow resistance characterization vector. The formula is as follows: In actual calculations, to ensure absolute dimensional consistency and avoid division-to-zero overflow, the frequency instruction increment... With real-time flow change rate All values ​​were normalized before being substituted into the formula. Specifically, Divide by the full-range reference value of the drive frequency , Divide by the upper limit of the rated pump flow rate. This transforms the ratio term involved in the calculation into a dimensionless quantity reflecting the proportion of physical deviations. As a small regularization term to prevent the denominator from being zero, it, along with the normalized ratio term, possesses dimensionless properties, thus satisfying the dimensional homogeneity of algebraic operations. This is a discrete flow impedance characterization vector. The frequency command increment for the current control cycle. The instantaneous flow rate change rate for the current control cycle. This is a constant preset within the adjustment control unit, with a value of 0.000001.

[0032] The filtering and adjustment section inside the control unit acquires pipe wall temperature data collected by the wall temperature acquisition unit from multiple symmetrical temperature measurement points within the heat tracing pipe section. It calculates the variance of the wall temperature among these symmetrical measurement points to determine the temperature spatial dispersion. When the temperature spatial dispersion exceeds a preset crystallization temperature threshold, the filtering and adjustment section reduces the cutoff frequency in the low-pass filter parameters from 4.5Hz to 0.5Hz to attenuate high-frequency noise. It also increases the proportional gain constant in the adjustment loop based on the downward trend of the pipe wall temperature data over time. Simultaneously, the transmission hysteresis compensation section inside the control unit monitors the response delay time between the issuance of the drive frequency control command and the flow response generated by the flow detection unit. When the response delay time monotonically increases with accumulated operating time, the transmission hysteresis compensation section superimposes a step-like frequency jump in the same direction as the fluid flow velocity when outputting the drive frequency control command, based on the slope of the response delay time change. Specifically, the slope of the response delay time reflects the expansion of the mechanical dead zone caused by wear of the transmission bearing. The control unit has a pre-stored linear empirical model of the delay time and mechanical clearance. ,in, This is the converted mechanical displacement clearance. The response delay time is measured in real time. Given the inherent delay constant of the equipment in its initial, wear-free state, and based on the torque-frequency response characteristics of the pumping mechanism, the amplitude of the stepped frequency jump is... The minimum starting frequency increment required to overcome this displacement gap is set, and the calculation formula is as follows: ,in, As a pre-calibrated frequency-to-displacement conversion coefficient, when executing the drive frequency output, the controller directly adds this amplitude to the original calculated frequency. The step signal is used to compensate for the idle stroke of the transmission chain, forcing the pumping mechanism to skip the motion stagnation zone, correcting the reduction in mechanical freedom caused by transmission bearing wear and clearing local crystal nuclei deposition in the pipeline.

[0033] The flow detection unit, wall temperature acquisition unit, regulation control unit, and drive frequency control unit work together to regulate the sudden change in flow viscosity resistance caused by the thermosensitive characteristics of high-concentration sulfuric acid inside the pipeline. When the opening and closing of the feeding valve causes pressure backflow or local heat tracing failure, the integral suspension module inside the regulation control unit suspends the integral accumulation of the regulation loop when a transient pressure impact occurs in the delivery pipeline, so as to eliminate integral saturation divergence, maintain the flow deviation variation rate within ±2.67%, and the steady-state deviation convergence delay of the regulation loop is 6.4s, so that the feeding process of the downstream reactor remains in a continuous operating state.

[0034] Example 2: When the system is in the fluid feed control valve regulation physical test platform, and the sulfuric acid raw material inside the conveying pipeline undergoes a sudden change in dynamic viscosity nonlinearly, the maximum pumping flow rate of the metering and conveying unit is set to 50.0 m³ / h and the steady-state control accuracy is set to 0.5%. The sampling rate of the turbine flow meter is set to 100 Hz and the resolution is set to 0.01 m³ / h. The temperature measurement resolution of the wall thermocouple array is set to 0.05 ℃. In this way, non-electrical physical quantities at various points in the pipeline are obtained. The value of the timing control cycle depends on the mutual constraint between the real-time update requirements of data acquisition and processing and the discrete numerical calculation load of the microprocessor. When the bandwidth of the characteristic frequency of the flow field pulsation increases, in order to reduce sampling aliasing and maintain the cutoff frequency margin of the control loop, the value of the timing control cycle is tightened towards a lower value. When the dominant disturbance frequency of the flow field is 10 Hz, its normal median value is determined to be 10 ms, its absolute lower limit is determined to be 5 ms to correspond to the high-frequency pulsation condition, and its absolute upper limit is determined to be 20 ms to correspond to the low power consumption boundary of the steady flow state.

[0035] To verify the performance of the flow deviation variation rate controlled collaboratively by the flow resistance inversion section, filter adjustment section, and transmission hysteresis compensation section in controlling the flow deviation variation rate, under normal median operating conditions with a timing control period of 10ms and a low-pass filter cutoff frequency of 0.5Hz, the flow deviation variation rate of the control group without flow resistance adjustment increased to 12.45%, while the flow deviation variation rate of the test group with full-unit collaborative adjustment remained at 1.12%. The flow deviation variation rate of the first control group with partial missing flow resistance inversion section removed increased to 5.83%, and the flow deviation variation rate of the second control group with partial missing filter adjustment section and transmission hysteresis compensation section removed increased to 6.14%. When performing numerical boundary tests on the sequential control cycle, the flow deviation variation rate of the test sample group set at the absolute lower limit of 5ms was 0.88%, and the flow deviation variation rate of the test sample group set at the absolute upper limit of 20ms was 2.58%. However, when the sequential control cycle was increased to 25ms to form the first control group for exceeding the range, the flow deviation variation rate increased sharply to 15.62%. Similarly, when performing boundary tests on the low-pass filter cutoff frequency, the flow deviation variation rate of the test sample group set at the absolute upper limit of 5.0Hz was 2.31%, and the flow deviation variation rate of the test sample group set at the absolute lower limit of 0.1Hz was 1.45%. When the low-pass filter cutoff frequency was reduced to 0.05Hz to form the second control group for exceeding the range, the flow steady-state deviation convergence delay was lengthened from 6.4s under normal conditions to 38.5s.

[0036] After 100 hours of continuous operation testing, no local blockage occurred in the feed channel of the test sample group. The discrete flow impedance output by the flow resistance inversion part stably tracked the transient trend of the medium viscosity. The transmission lag compensation part offset the mechanical fit clearance by superimposing the step-like jump frequency in the drive frequency control command according to the change slope of the response delay time. The wear depth of the pump hub wall after disassembly was less than 0.02mm and the amount of crystallization on the inner wall of the flow channel remained below 0.05g / m². The material flow and control signal flow inside the fluid transport circuit maintained a steady-state balance under the discrete-time topology architecture, thereby limiting the flow fluctuation within the controlled range by the regulating circuit at the pipeline outlet.

[0037] Example 3: When the system faces a crystallization environment caused by the local heat exchange efficiency decay in the heat tracing pipe section, and the flow field stress impact induced by the downstream batching valve being shut off, the non-electric variable regulation loop at the pipeline outlet is at risk of control instability. Based on the nonlinear characteristics of the crystallization kinetics within the controlled fluid, a fixed temperature control threshold is difficult to match the local supersaturation changes at different flow rates. The resulting lag causes solid micronuclei to adhere to the surface of the feed channel, leading to localized agglomeration and obstruction in the pipeline. Furthermore, under the backlash of fluid kinetic energy generated by the batching cutoff waveform, the discrete integral term of the control loop experiences saturation overflow, thus lengthening the convergence delay for the system to return to a stable flow state. Before the process starts, the filter regulation section inside the control unit is adjusted to obtain the nominal concentration value of the controlled sulfuric acid medium at the working pressure, and a preset value is retrieved. The saturated crystallization temperature reference is used to calculate the dynamic crystallization control limit by monitoring the rate of change of local wall temperature in the heat tracing pipe section. The wall temperature acquisition unit periodically collects real-time temperature data of the symmetrical temperature measurement point cluster with an independent sampling window of 10ms. The adjustment and control unit calculates the first derivative of temperature of 5 consecutive sampling points to characterize the local cooling rate. When the first derivative of temperature monotonically crosses the critical decay slope of 0.15℃ / s, and the lowest local measured temperature in the symmetrical temperature measurement point cluster drops to the oversaturation trigger range of 3.2℃ higher than the saturated crystallization temperature reference, the filter adjustment part locks the current state and then triggers the adjustment of the low-pass filter parameters, switching the low-pass filter cutoff frequency from 4.5Hz to 0.5Hz in a step, thereby cutting off the peak noise current generated by the friction and collision of impurities in the solid-liquid two-phase flow on the power output side.

[0038] The flow detection unit monitors the real-time flow data of the controlled fluid, and the regulation and control unit calculates the instantaneous flow rate change within the current timing control cycle based on the real-time flow data. When the instantaneous flow rate changes When the following relationship is satisfied: Considering the turbine flow meter's sampling period is 10ms, the control unit internally divides the flow difference between two consecutive sampling periods by 10ms to obtain the initial rate of change. To achieve high sensitivity with nanosecond-level response, a preset backflush strength threshold is set. To achieve order-of-magnitude matching, the processing chip performs second-order interpolation on the flow rate change within 10ms using its internal clock, fitting it to a unit rate of change on the order of microseconds. This compensates for the phase lag in the sampling of the flow sensor's mechanical rotational inertia. A high-frequency pressure sensor with a sampling frequency of 10kHz and a measurement accuracy of 0.1% is installed at the pump outlet. The control unit acquires the pressure pulse sequence from the high-frequency pressure sensor. Utilizing the near-sound-speed transmission characteristics of pressure waves in the medium, the internal pressure distortion characteristics of the flow field are pre-captured before the flow rate drops. The high-frequency pressure variation is correlated in the time domain with the interpolated flow rate change data to calibrate the sampling discretization observation bias. This is achieved by mapping the apparent variation within 10 ms to a 1 μs time base and obtaining normalized eigenvalues, thus enabling the advanced capture of transient pressure recoil waves in pipelines under discrete sampling conditions. For real-time flow change rate, For absolute value operators, The preset recoil strength threshold is set to a value of [value missing]. Every microsecond, the integral suspension module inside the control unit sends a suspension command to the status register of the proportional-integral regulator, locking the integral accumulation term in the current timing control cycle to the historical value of the previous adjacent control cycle, thereby preventing integral increment saturation caused by a sudden increase in flow deviation.

[0039] Under the combined effect of adaptive dynamic crystallization control limit calculation and historical value locking of the state register, needle-like crystal deposits caused by local cold spots inside the feeding channel are suppressed. Furthermore, the control loop blocks integral saturation divergence when faced with transient pressure backlash caused by cutoff, keeping the flow deviation variation rate within ±2.67% of the conveying pipeline. The steady-state deviation convergence delay of the loop recovering from flow disturbance to a stable flow state is controlled within 6.4s, thereby maintaining stable material chemical reaction property data in the downstream reactor feeding process. The entire feeding and conveying system maintains continuous operation. When the system faces extreme conditions where the conveying pipeline is completely blocked and the integral suspension module suspends the integral accumulation of the regulating loop, the transient flow data input by the flow detection unit to the regulating control unit remains at zero for an extended period, and the transient static pressure parameter output by the friction-side pressure sensing array exceeds the preset safety upper limit threshold of 0.6MPa, determining that the feeding channel is completely blocked. The system then switches the protection state of the control state machine. Specifically, the protection track includes a series of cascaded operational logics: the state machine triggers integral suspension. The flag bit writes the preset minimum safety maintenance frequency to the output register. When the state machine detects that the pressure parameter along the flow exceeds 0.6MPa and the duration exceeds 3 control cycles, the protection track automatically jumps to the pressure relief return node and sends a switching level to the solenoid valve group through the I / O port. The regulating control unit sends a valve control command to the safety pressure relief return unit, driving it to open the safety return valve to guide the high-pressure fluid into the safety pressure relief circuit. At the same time, the forward control bus inside the control chip forcibly limits the maximum output power of the proportional gain constant to no more than 5% of the normal maximum power to suppress the inverter bridge current surge of the frequency converter. The regulating control unit also sends a drive level to the relay output terminal of the flushing unit, driving the active metering pump of the flushing unit to start and inject a sodium hydroxide alkaline solution with a nominal concentration of 15% into the delivery pipeline to complete the neutralization, dissolution, and washing of the crystallized agglomerates in the pipe. After the transient static pressure parameter along the flow drops back to the normal flushing pressure range of 0.1MPa and the duration reaches 300s, the regulating control unit shuts down the flushing unit and resets the proportional term gain of the main regulating circuit to restore the standby regulating state.

[0040] Example 4: Under the parameter calibration conditions before the first operation of the conveying pipeline, in order to establish the reference physical property data for subsequent flow resistance feedback control and filter adjustment, the inside of the feeding channel is placed in an initial state with no flow and the ambient temperature is constant at 20.0℃. The symmetrical temperature measurement point cluster of the wall temperature acquisition unit performs static multi-point temperature sampling on the concentrated sulfuric acid medium with a nominal concentration of 98% injected into the pipeline, and establishes the initial pipeline wall temperature reference to eliminate the local heat transfer differences in each channel. At the same time, sulfuric acid standard fluid with a known flow gradient is continuously injected into the conveying pipeline through an external calibration pump. The turbine flow meter of the flow detection unit obtains the corresponding pulse count sequence, and the adjustment control unit calculates the monotonic mapping slope between the pulse frequency and the actual volume flow rate. This monotonic mapping slope is written into the static random access memory of the control chip as the zero point correction amount of the flow sensor.

[0041] When the system faces discrete signal changes caused by mechanical wear of the pipeline inner wall and aging of the flow meter, the control unit retrieves the zero-point correction value of the flow sensor stored in the static random access memory within 10ms of each timing control cycle to apply linear bias calibration to the collected real-time flow data. When calculating the drive frequency control command, the transmission mechanical clearance parameter calculated by the time delay difference is introduced. The transmission lag compensation part increases the in-situ superimposed step jump frequency according to the transmission mechanical clearance parameter, shortening the control blind zone time caused by bearing wear in the physical pipeline to within 15.0ms, and clamping the steady-state pressure pulsation amplitude of the fluid at the feed channel outlet within the range of ±0.02MPa.

[0042] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A stable conveying system for sulfuric acid feedstock, characterized in that, include: The flow detection unit is used to collect real-time flow data of the delivery pipeline; The wall temperature acquisition unit is used to collect the pipe wall temperature data of the heat tracing pipe section; The regulating control unit connects the flow detection unit and the wall temperature acquisition unit. It is used to calculate and output drive frequency control commands based on real-time flow data and pipeline wall temperature data. The regulating control unit includes a flow resistance inversion section, a filter regulation section, and a transmission hysteresis compensation section. The flow resistance inversion section is used to compare the frequency command increment with the flow rate change rate to determine the trend of fluid mass transfer flow resistance. The filter adjustment section is used to calculate the temperature spatial dispersion based on the pipe wall temperature data, and when the temperature spatial dispersion is greater than the preset crystallization temperature threshold, the cutoff frequency of the low-pass filter parameter is reduced, and the proportional gain constant is increased according to the time downward trend of the pipe wall temperature data. The transmission lag compensation section is used to calculate the transmission mechanical clearance parameters when the response delay time between the drive frequency control command and the real-time flow data increases monotonically, and to superimpose a stepped frequency jump when outputting the drive frequency control command. The drive frequency control unit, connected to the adjustment control unit, is used to adjust the output power of the pumping mechanism according to the drive frequency control command.

2. The sulfuric acid feedstock stable conveying system according to claim 1, characterized in that, The regulating control unit also includes an integral suspension module. When a transient pressure shock occurs in the delivery pipeline, the integral suspension module suspends the integral accumulation of the regulating loop and corrects the steady-state deviation of the control loop according to the anti-saturation correction coefficient.

3. The sulfuric acid raw material feeding and stable conveying system according to claim 1, characterized in that, The regulating control unit includes a temperature sampling cluster for multi-point settlement of pipeline wall temperature data; the temperature sampling cluster is arranged on multiple symmetrical temperature measurement points in the heat tracing pipe section to obtain real-time wall temperature, and the regulating control unit calculates the wall temperature variance between multiple symmetrical temperature measurement points, using the wall temperature variance as the temperature spatial dispersion.

4. The sulfuric acid feedstock stable conveying system according to claim 1, characterized in that, When determining the trend of change, the control unit separates the phase lag of the flow response and adjusts the incremental direction of the drive frequency control command to be monotonically opposite to the transient rate of change of the real-time flow data.

5. The sulfuric acid feedstock stable conveying system according to claim 1, characterized in that, The control unit records the response delay time of the drive frequency control command and real-time flow data. When the response delay time monotonically increases with the cumulative running time, the rate of increase is used as the bearing wear index of the pumping mechanism. When the bearing wear index reaches the preset safety threshold, a maintenance warning signal is output to the external system.

6. The sulfuric acid feedstock stable conveying system according to claim 1, characterized in that, The cutoff frequency of the low-pass filter parameter can be adjusted from 0.1Hz to 5.0Hz; when the temperature space dispersion is not greater than the crystallization temperature threshold, the cutoff frequency is 4.5Hz; when the temperature space dispersion is greater than the crystallization temperature threshold, the control unit adjusts the cutoff frequency to 0.5Hz.

7. The sulfuric acid feedstock stable conveying system according to claim 1, characterized in that, The crystallization temperature threshold is pre-calibrated based on the crystallization characteristic curve of sulfuric acid at different ambient temperatures; the control unit uses the point of change in the cooling rate in the pipeline wall temperature data as the trigger limit of the crystallization temperature threshold.

8. The sulfuric acid feedstock stable conveying system according to claim 1, characterized in that, The control unit includes a transient distortion calibration sub-section for suppressing sudden abnormal interference flow resistance; the transient distortion calibration sub-section calculates the second difference between the feedback current data of the drive frequency control unit in the current control cycle and the values ​​of the two adjacent historical control cycles to generate a current distortion slope variable, and performs in-situ correction of the proportional gain constant of the flow deviation based on the current distortion slope variable and the rate of change of the temperature spatial dispersion.

9. A stable conveying system for sulfuric acid feedstock according to claim 2, characterized in that, It also includes a safety pressure relief and return unit and a flushing unit connected to the delivery pipeline; when the integral suspension module suspends the integral accumulation of the adjustment circuit and the delivery pipeline is completely blocked, the safety pressure relief and return unit opens the safety return valve, limits the maximum output power of the proportional gain constant, and drives the flushing unit to inject alkali into the delivery pipeline.

10. A method for stable conveying of sulfuric acid feedstock, used to operate the stable conveying system for sulfuric acid feedstock as described in claim 1, characterized in that, include: Step S1: Collect real-time flow data of the delivery pipeline through the flow detection unit; Step S2: Collect pipe wall temperature data of the heat tracing pipe section through the wall temperature acquisition unit; Step S3: The control unit calculates and outputs a drive frequency control command based on real-time flow data and pipe wall temperature data. Step S4: The output power of the pumping mechanism is adjusted by the drive frequency control unit according to the drive frequency control command; wherein, the control unit calculates and outputs the drive frequency control command based on real-time flow data and pipeline wall temperature data. Step S5: By comparing the frequency command increment with the flow rate change rate in the flow resistance inversion section, the variation trend of fluid mass transfer flow resistance is determined. Step S6: The temperature spatial dispersion is calculated based on the pipe wall temperature data by the filtering adjustment section. When the temperature spatial dispersion is greater than the preset crystallization temperature threshold, the cutoff frequency of the low-pass filter parameter is reduced, and the proportional gain constant is increased according to the downward trend of the pipe wall temperature data over time. Step S7: Through the transmission lag compensation part, when the response delay time between the drive frequency control command and the real-time flow data increases monotonically, the transmission mechanical clearance parameter is calculated, and a step-like frequency jump is superimposed when the drive frequency control command is output.

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