On-line monitoring method for solvent volatilization rate and fluidity of silicon steel coating liquid circulating system

Abstract

The invention discloses an online monitoring method for the solvent volatilization rate and fluidity of a silicon steel coating liquid circulation system. The method comprises the following steps: collecting the temperature of a coating liquid, the solvent vapor concentration of a gas space at the top of a circulation tank, the running power of a motor of a circulation pump and the circulation flow of the coating liquid in real time; the solvent volatilization rate and the coating liquid fluidity are calculated according to the collected data, the solvent loss amount in unit time is calculated through the solvent volatilization rate, and the starting frequency and duration of a solvent adding pump are controlled; setting an upper limit and a lower limit of viscosity, if the fluidity is greater than the upper limit, warning that the fluidity is poor; when the fluidity is lower than the lower limit, the solid content is low; and if the fluidity shows an irreversible continuous increasing trend, early warning is performed to prompt that the coating liquid is aged and needs to be replaced. According to the method, the defects of traditional coating liquid solvent volatilization rate and fluidity detection are overcome, key process data of the liquid solvent volatilization rate and fluidity are calculated through easily-detected parameters, and real-time sensing and accurate regulation and control of the state of the coating liquid in the circulation tank are achieved.

Description

Technical Field

[0002] This invention relates to the field of detection technology, and in particular to an online monitoring method for solvent evaporation rate and flowability of a silicon steel coating liquid circulation system. Background Technology

[0004] Monitoring the solvent evaporation rate and flowability of silicon steel coating liquid is of great significance in ensuring coating quality stability, optimizing production costs, ensuring production continuity, and achieving refined management.

[0005] Currently, the solvent evaporation rate of coating solutions cannot be monitored online. Typically, operators rely on periodically observing changes in the liquid level in the circulating tank and manually adding solvent based on experience. Alternatively, samples are periodically sent to a laboratory to measure changes in solid content and extrapolate the evaporation rate, resulting in significantly delayed data. This lack of data-driven approach to solvent addition, relying entirely on experience, leads to inaccurate dosages, solvent waste, and deviations of the coating solution composition from the process window, ultimately impacting product quality.

[0006] The fluidity of coating solutions also lacks online monitoring. Typically, offline viscosity cups (such as Ford cups) are used for periodic sampling and measurement, which is time-consuming and labor-intensive. Furthermore, the measurement results are greatly affected by human factors and cannot reflect the true fluidity status of the coating solution in the circulation pipeline. Offline fluidity (viscosity) measurements are infrequent and have poor representativeness, making it impossible to detect viscosity change trends in a timely manner and to provide early warnings of the risk of circulation pipeline blockage due to deteriorating fluidity. It also fails to predict the risk of fluidity loss due to aging, polymerization, or precipitation of the coating solution.

[0007] Therefore, all process adjustments to the coating liquid (solvent addition, temperature control, speed adjustment) are based on experience and offline data, which cannot form a closed-loop control, resulting in poor process stability. The risk of pump and pipeline blockage due to deterioration of flowability cannot be predicted. Because all process adjustments are open-loop, real-time feedback control based on the actual system status is impossible.

[0008] Monitoring solvent evaporation rate and flowability is crucial because both directly affect the uniformity and adhesion of the coating, which in turn influences the insulation performance of silicon steel and the magnetic properties of the final product. Current technology for managing coating liquid circulation tanks is inefficient and outdated. There is no online monitoring method for solvent evaporation rate; it relies entirely on operators periodically observing the liquid level and manually adding solvent based on experience, or on offline sampling and laboratory measurements of solid content to extrapolate the data. Similarly, coating liquid flowability (viscosity) is measured offline and manually, such as periodically using viscosity cups. Neither of these methods reflects the real-time dynamic changes in parameters during production, resulting in severely delayed data. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide an online monitoring method for solvent evaporation rate and flowability of silicon steel coating liquid circulation system. This method overcomes the defects of traditional coating liquid solvent evaporation rate and flowability detection, and calculates the key process data of liquid solvent evaporation rate and flowability through easily measurable parameters, so as to realize real-time perception and precise control of the coating liquid state in the circulation tank.

[0011] To solve the above-mentioned technical problems, the present invention provides an online monitoring method for solvent evaporation rate and flowability of a silicon steel coating liquid circulation system, comprising the following steps:

[0012] Step 1: Data acquisition. Real-time data acquisition includes coating liquid temperature T, solvent vapor concentration C in the top gas space of the circulation tank, circulation pump motor operating power P, and coating liquid circulation flow rate Q.

[0013] Step 2: Solvent evaporation rate calculation.

[0014] (1)

[0015] Where Rate_evap is the solvent evaporation rate, C_sat(T) is the solvent saturated vapor concentration at the current temperature T, which is calculated based on the solvent properties or obtained from a table, and K is the calibration coefficient, which is determined through experimental data;

[0016] Calculation of coating liquid flowability

[0017] μ=K_μ×(P / Q) (2)

[0018] Where μ is the apparent viscosity of the coating liquid, and K_μ is the viscosity calibration coefficient, which is obtained by measuring the actual viscosity μ_offline using an offline viscometer and then calibrating it using K_μ=μ_offline×Q / P;

[0019] Step 3: Solvent replenishment control. Integrate the solvent evaporation rate Rate_evap to calculate the solvent loss M_loss per unit time. Use this signal as a feedforward signal to control the start frequency and duration of the solvent addition pump, so as to achieve precise solvent replenishment.

[0020] Step 4: Monitoring and alarming the fluidity of the coating liquid. Set the upper limit μ_max and lower limit μ_min of viscosity. When μ > μ_max, an alarm will be triggered indicating poor fluidity, and the temperature regulation unit will be automatically activated to appropriately increase the temperature of the circulating tank. When μ < μ_min, an alarm will be triggered indicating that the solid content is too low.

[0021] Step 5: Trend Analysis and Early Warning. Record the apparent viscosity μ of the coating liquid over a long period of time. If μ shows an irreversible and continuous upward trend, an early warning will be issued indicating that the coating liquid is aging and needs to be replaced.

[0022] Furthermore, in step one, a temperature sensor is inserted into the coating liquid circulation tank to collect the coating liquid temperature T in real time; a PID photoionization sensor is installed in the gas space at the top of the circulation tank to collect the solvent vapor concentration C in real time; a power transmitter is installed in the power distribution circuit of the circulation pump motor to collect the motor operating power P in real time; and an electromagnetic flow meter is installed on the outlet pipe of the circulation pump to collect the circulation flow rate Q of the coating liquid in real time.

[0023] Furthermore, all collected data, solvent evaporation rate calculation data, coating liquid flowability calculation data, as well as trend analysis and alarm information are displayed through a human-machine interface, which also provides a manual intervention interface.

[0024] The present invention employs the above-mentioned technical solution for online monitoring of solvent evaporation rate and fluidity in a silicon steel coating liquid circulation system. Specifically, this method collects real-time data on coating liquid temperature, solvent vapor concentration in the top gas space of the circulation tank, circulation pump motor operating power, and coating liquid circulation flow rate. Based on the collected data, it calculates the solvent evaporation rate and coating liquid fluidity, using the solvent evaporation rate to calculate the solvent loss per unit time and control the start frequency and duration of the solvent addition pump. It sets upper and lower viscosity limits; if fluidity exceeds the upper limit, an alarm indicates poor fluidity, prompting an increase in the circulation tank temperature; if fluidity is below the lower limit, an alarm indicates low solids content; if fluidity shows an irreversible and continuous increasing trend, a warning is issued indicating that the coating liquid is aging and needs replacement. This method overcomes the shortcomings of traditional coating liquid solvent evaporation rate and fluidity detection methods, using easily measurable parameters to deduce key process data on solvent evaporation rate and fluidity, achieving real-time perception and precise control of the coating liquid state within the circulation tank. Attached Figure Description

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0027] Figure 1 This is a flowchart of the online monitoring method for solvent evaporation rate and flowability of the silicon steel coating liquid circulation system of the present invention. Detailed Implementation

[0029] Implementation, for example Figure 1 As shown, the online monitoring method for solvent evaporation rate and flowability of the silicon steel coating liquid circulation system of the present invention includes the following steps:

[0030] Step 1: Data acquisition. Real-time data acquisition includes coating liquid temperature T, solvent vapor concentration C in the top gas space of the circulation tank, circulation pump motor operating power P, and coating liquid circulation flow rate Q.

[0031] Step 2: Solvent evaporation rate calculation.

[0032] (1)

[0033] Where Rate_evap is the solvent evaporation rate, C_sat(T) is the solvent saturated vapor concentration at the current temperature T, which is calculated based on the solvent properties or obtained from a table, and K is the calibration coefficient, which is determined through experimental data;

[0034] Calculation of coating liquid flowability

[0035] μ=K_μ×(P / Q) (2)

[0036] Where μ is the apparent viscosity of the coating liquid, and K_μ is the viscosity calibration coefficient, which is obtained by measuring the actual viscosity μ_offline using an offline viscometer and then calibrating it using K_μ=μ_offline×Q / P;

[0037] Step 3: Solvent replenishment control. Integrate the solvent evaporation rate Rate_evap to calculate the solvent loss M_loss per unit time. Use this signal as a feedforward signal to control the start frequency and duration of the solvent addition pump, so as to achieve precise solvent replenishment.

[0038] Step 4: Monitoring and alarming the fluidity of the coating liquid. Set the upper limit μ_max and lower limit μ_min of viscosity. When μ > μ_max, an alarm will be triggered indicating poor fluidity, and the temperature regulation unit will be automatically activated to appropriately increase the temperature of the circulating tank. When μ < μ_min, an alarm will be triggered indicating that the solid content is too low.

[0039] Step 5: Trend Analysis and Early Warning. Record the apparent viscosity μ of the coating liquid over a long period of time. If μ shows an irreversible and continuous upward trend, an early warning will be issued indicating that the coating liquid is aging and needs to be replaced.

[0040] Preferably, in step one, a temperature sensor is inserted into the coating liquid circulation tank to collect the coating liquid temperature T in real time; a PID photoionization sensor is installed in the gas space at the top of the circulation tank to collect the solvent vapor concentration C in real time; a power transmitter is installed in the power distribution circuit of the circulation pump motor to collect the motor operating power P in real time; and an electromagnetic flow meter is installed on the outlet pipe of the circulation pump to collect the circulation flow rate Q of the coating liquid in real time.

[0041] Preferably, all collected data, solvent evaporation rate calculation data, coating liquid flowability calculation data, trend analysis and alarm information are displayed through a human-machine interface, and the human-machine interface provides a manual intervention interface.

[0042] This method employs "multi-sensor fusion estimation of evaporation rate + indirect viscosity measurement based on pump power + intelligent closed-loop control," which solves the core pain point of the inability to monitor solvent evaporation rate and coating liquid flowability online, and realizes real-time perception and precise control of the coating liquid state in the circulating tank.

[0043] This innovative method integrates easily measurable parameters such as temperature (T) and concentration (C) through a physical empirical model to estimate the solvent evaporation rate (Rate_evap), which is difficult to measure directly, in real time. This provides a unique data foundation for precise closed-loop control of solvent addition, solving a major industry pain point. Utilizing the intrinsic relationship between circulating pump power (P), flow rate (Q), and fluid viscosity (μ), calibration enables online, real-time, and indirect measurement of viscosity, a key flowability indicator, achieving low cost and high reliability. The real-time evaporation rate calculated using soft sensing is used as a feedforward signal, integrated, and directly controls the addition pump's operation, achieving precise control of "replenishing as needed, replenishing only what is lost," completely changing the experience-based manual mode. Simultaneously, long-term trend analysis of online viscosity data allows for early identification of performance degradation trends in coating solutions due to aging and polymerization, enabling a shift from preventative to predictive replacement and avoiding sudden failures.

[0044] This method ensures consistent coating quality and performance: the solvent evaporation rate directly affects the solids content and viscosity of the coating solution. Excessive evaporation leads to increased solids content and viscosity, causing the coating amount to deviate from the set value, resulting in an overly thick coating, cracking, and decreased adhesion; excessively slow evaporation may lead to poor coating drying; and fluidity directly affects the uniformity of the coating. Poor fluidity can cause defects such as streaks and orange peel in the coating, severely affecting the insulation quality and appearance of the silicon steel sheet.

[0045] Reduce production costs and minimize waste: Solvents are a crucial and expensive component in coating solutions. Real-time monitoring of evaporation rates can precisely guide the quantitative replenishment of solvent, avoiding waste caused by excessive addition based on experience, or waste of the coating solution due to insufficient replenishment.

[0046] Preventing production interruptions and equipment failures: A sharp decrease in fluidity (a sudden increase in viscosity) can lead to pipe blockages, excessive pump loads, or even pump seizures, causing unplanned downtime. Real-time monitoring can effectively provide early warnings of such risks.

[0047] Achieve precise closed-loop control of process parameters: Provide real-time and accurate feedback signals for temperature control, stirring speed control, and automatic solvent addition system of coating liquid, realizing a leap from "experience control" to "data-driven control".

Claims

1. A method for online monitoring of solvent evaporation rate and flowability in a silicon steel coating liquid circulation system, characterized in that... Includes the following steps: Step 1: Data acquisition. Real-time data acquisition includes coating liquid temperature T, solvent vapor concentration C in the top gas space of the circulation tank, circulation pump motor operating power P, and coating liquid circulation flow rate Q. Step 2: Solvent evaporation rate calculation. （1） Where Rate_evap is the solvent evaporation rate, C_sat(T) is the solvent saturated vapor concentration at the current temperature T, which is calculated based on the solvent properties or obtained from a table, and K is the calibration coefficient, which is determined through experimental data; Calculation of coating liquid flowability μ=K_μ×(P / Q) (2) Where μ is the apparent viscosity of the coating liquid, and K_μ is the viscosity calibration coefficient, which is obtained by measuring the actual viscosity μ_offline using an offline viscometer and then calibrating it using K_μ=μ_offline×Q / P; Step 3: Solvent replenishment control. Integrate the solvent evaporation rate Rate_evap to calculate the solvent loss M_loss per unit time. Use this signal as a feedforward signal to control the start frequency and duration of the solvent addition pump, so as to achieve precise solvent replenishment. Step 4: Monitoring and alarming the fluidity of the coating liquid. Set the upper limit μ_max and lower limit μ_min of viscosity. When μ > μ_max, an alarm will be triggered indicating poor fluidity, and the temperature regulation unit will be automatically activated to appropriately increase the temperature of the circulating tank. When μ < μ_min, an alarm will be triggered indicating that the solid content is too low. Step 5: Trend Analysis and Early Warning. Record the apparent viscosity μ of the coating liquid over a long period of time. If μ shows an irreversible and continuous upward trend, an early warning will be issued indicating that the coating liquid is aging and needs to be replaced.

2. The method for online monitoring of solvent evaporation rate and flowability of silicon steel coating liquid circulation system according to claim 1, characterized in that: In step one, a temperature sensor is inserted into the coating liquid circulation tank to collect the coating liquid temperature T in real time; a PID photoionization sensor is installed in the gas space at the top of the circulation tank to collect the solvent vapor concentration C in real time; a power transmitter is installed in the power distribution circuit of the circulation pump motor to collect the motor operating power P in real time; and an electromagnetic flow meter is installed on the outlet pipe of the circulation pump to collect the circulation flow rate Q of the coating liquid in real time.

3. The method for online monitoring of solvent evaporation rate and flowability of silicon steel coating liquid circulation system according to claim 1 or 2, characterized in that: All collected data, solvent evaporation rate calculation data, coating liquid flowability calculation data, trend analysis, and alarm information are displayed through a human-machine interface, which also provides a manual intervention interface.

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