Intelligent control system of NMP tail gas treatment device

Abstract

The application relates to the technical field of intelligent control of industrial waste gas treatment, and discloses an intelligent control system of an NMP tail gas treatment device; the intelligent control system adopts a three-level architecture of a perception layer, a control layer and an execution layer, and realizes full-process quantitative closed-loop linkage control by locking two core control indexes; the perception layer is arranged with detection sensors matched with the two core control indexes; the control layer is an industrial intelligent controller, which is internally provided with four core mathematical control models coupled and linked; and the execution layer comprises a deep-cooling condensation execution unit and a spraying absorption execution unit; the application guarantees removal efficiency from the source by stabilizing dry gasification effect under the working condition state, accurately regulates and controls the dry gasification control standard through a quantitative model, solves the defect that the condensation effect optimization in the prior art cannot fundamentally solve the liquid droplet entrainment problem, lays a solid foundation for NMP removal efficiency standard, and stabilizes NMP removal efficiency to meet environmental protection requirements; the dry gasification is used as a pre-constraint, and the removal efficiency control standard is accurately regulated and controlled.

Description

Technical Field

[0001] This invention relates to the field of intelligent control technology for industrial waste gas treatment, specifically to an intelligent control system for an NMP exhaust gas treatment device. Background Technology

[0002] N-Methylpyrrolidone (NMP) is a commonly used industrial solvent in industries such as lithium battery coating and electronic insulation material production. Its exhaust gas emissions must be strictly purified to 1 mg / m³. 3 The following measures are taken to meet stringent environmental protection requirements. In existing technologies, the mainstream treatment process for NMP exhaust gas is a combination of condensation and multi-stage spray absorption. Related patents primarily focus on optimizing the condensation, absorption, and recovery structure of NMP exhaust gas. Several patents related to this technology have been published, such as the new patent CN 220026531 U (an NMP production exhaust gas treatment device), invention patent CN202310378572.2 (a high-efficiency recovery device containing NMP exhaust gas), and invention patent application CN121624063A (an integrated NMP recovery system and working method combining double-sided coating and drying oven), etc. All of these patents optimize the condensation, absorption, and recovery structure of NMP exhaust gas, attempting to improve condensation efficiency and absorption efficiency.

[0003] However, existing technologies have core technical defects, failing to address the key issues of quantitative control and intelligent linkage in NMP exhaust gas treatment: First, there is no quantitative dry gasification control standard for condensation, and the problem of droplet entrainment remains unresolved. Manual adjustment of condensation temperature and cooling capacity lacks clear guidelines, resulting in the entrainment of tiny droplets in the exhaust gas entering the spray tower. Droplet-state NMP cannot be dissolved and removed through spraying, becoming the core cause of decreased NMP removal efficiency. Second, spray absorption parameters rely on manual adjustment, and there is no quantitative closed-loop control for NMP removal efficiency. It is impossible to dynamically match optimal parameters based on real-time exhaust gas conditions, easily leading to emission concentration fluctuations between 11-19 mg / m³. 3 The situation is much higher than 1 mg / m³. 3 The standards are as follows: First, there is no intelligent linkage between the condensation and spray absorption units, resulting in a disconnect in the entire process control. The two units operate independently, and the detection data of the condensation and dry gasification effect is not used as the input condition for adjusting the spray absorption parameters, which leads to a large fluctuation in the overall NMP removal efficiency. Second, there is no dedicated intelligent control system, and manual operation leads to high energy consumption and large errors. In order to ensure compliance, parameters are often over-adjusted, resulting in energy consumption and material waste. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent control system for an NMP exhaust gas treatment device to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an intelligent control system for an NMP exhaust gas treatment device, wherein the NMP exhaust gas treatment device includes a cryogenic refrigerant unit, a cryogenic refrigerator, a gas-liquid separator, a surface cooler + demister, a three-stage spray tower, a fan, a circulating liquid pump, and a self-priming pump, characterized in that the intelligent control system adopts a three-level architecture of a sensing layer, a control layer, and an execution layer, and locks two core control indicators to achieve full-process quantitative closed-loop linkage control; The two core control indicators include: Cryogenic condensation and dry gasification control indicators: the dew point of the exhaust gas at the outlet of the gas-liquid separator (i.e., the inlet of the spray tower) is ≤10℃ and the content of micro-droplets is ≤0.01mg / m³. 3 ; NMP removal efficiency control target: The NMP removal efficiency of the tail gas at the outlet of the three-stage spray tower is ≥99.99%, corresponding to an NMP content of ≤1mg / m³ in the tail gas. 3 It is suitable for operating conditions with an inlet NMP concentration of 250-350 ppm; The sensing layer is equipped with detection sensors that match the two core control indicators. The acquisition frequency is 2 seconds / time. These sensors are used to collect data on exhaust gas flow rate, exhaust gas inlet and outlet NMP concentration, cryogenic refrigerator inlet and outlet temperature, gas-liquid separator outlet dew point and micro-droplet content, spray tower empty tower gas velocity, circulating liquid total flow rate, spray tower inlet and outlet gas temperature, and tower bottom liquid level, and transmit the data to the control layer. The control layer is an industrial intelligent controller, which has four core mathematical control models that are coupled and linked: a cryogenic condensation temperature regulation model, a cryogenic refrigerant unit cooling capacity regulation model, an NMP removal efficiency core model, and a spray parameter comprehensive regulation model. It takes the achievement of dry gasification control indicators as a prerequisite constraint and the achievement of NMP removal efficiency control indicators as the final goal, calculates the optimal operating parameters and outputs control commands. The execution layer includes a cryogenic condensation execution unit and a spray absorption execution unit, with a response time of ≤1s. The cryogenic condensation execution unit is used to adjust the condensation temperature, cooling capacity, and condensate discharge, while the spray absorption execution unit is used to adjust the fan frequency, circulating liquid pump frequency, and chilled water flow rate, accurately executing the control layer commands.

[0006] Preferably, the detection sensor of the sensing layer specifically includes: Supporting sensors for dry gasification indicators: dew point sensor at gas-liquid separator outlet, online micro-droplet detector, cryogenic refrigerator outlet temperature sensor, and condensate level sensor for gas-liquid separator. Sensors supporting the removal efficiency indicators: NMP concentration sensor at the spray tower inlet, NMP concentration sensor at the spray tower outlet, air velocity sensor in the spray tower empty tower, total flow rate sensor of circulating liquid, air temperature sensor at the spray tower inlet and outlet, and liquid level sensor at the bottom of the three-stage spray tower.

[0007] Preferably, the calculation formula for the cryogenic condensation temperature regulation model is as follows: Tc = Td - K1·lg(Cd / Cd0) - K2·(Q tail / 2000) In the formula: Tc is the target condensing temperature at the outlet of the cryogenic refrigerator, in °C; Td is the dew point threshold of the dry vaporization index, taken as 10 °C; Cd is the droplet content threshold of the dry vaporization index, taken as 0.01 mg / m³. 3 Cd0 is the baseline value for droplet concentration, and the device is calibrated to 0.1 mg / m³. 3 Q represents the real-time exhaust gas flow rate, in meters per second (m³). 3 / h; K1 is the droplet-condensation temperature coupling coefficient, calibrated to 8.5; K2 is the flow rate-condensation temperature correction coefficient, calibrated to 2.3.

[0008] Preferably, the calculation formula for the cooling capacity adjustment model of the cryogenic refrigerant unit is as follows: Q_cold = K3·(T_tail - T_c)·Q_tail·C In the formula: Qcold is the target cooling capacity of the cryogenic refrigerant unit, in kJ / h; Ttailin is the inlet exhaust gas temperature of the cryogenic refrigerator, in °C, collected by the sensing layer; K3 is the cooling efficiency correction coefficient, calibrated to 1.12; C is the isobaric specific heat capacity of the NMP exhaust gas, calibrated to 1.05 kJ / (m2). 3 ·℃).

[0009] Preferably, the control layer has built-in pre-constraint logic: when the control index of cryogenic condensation dry gasification fails to meet the standard, the NMP removal efficiency regulation model is locked, the cryogenic condensation dry gasification regulation model is started first, and the control logic of the spray absorption unit is unlocked after the dry gasification index meets the standard.

[0010] Preferably, the NMP removal efficiency core model only takes effect when the dry gasification index meets the standard, and its calculation formula is as follows: η = 1 - (K4·U1.2·C0.8) / (L1.5·(Tin - Tout)0.9) In the formula: η is the NMP removal efficiency, with a target threshold of ≥99.99%; U is the empty gas velocity of the spray tower, in m / s, ranging from 6.94 to 13.89 m / s; C is the NMP concentration of the circulating liquid in the first-stage spray tower, in %, ranging from 0 to 90%; L is the spray density, i.e., the total flow rate of the circulating liquid, in kg / h, ranging from 911 to 1823 kg / h; Tin / Tout are the inlet / outlet temperatures of the spray tower, with control targets of 13℃ / 10℃ respectively; K4 is the gas-liquid mass transfer coefficient after dry gasification meets the standard, calibrated to 0.023.

[0011] Preferably, the integrated spray parameter adjustment model includes a fan frequency adjustment sub-model and a circulating liquid pump frequency adjustment sub-model: Fan frequency: fJ = ​​fJ0·(U·S / Q tail stem)·K5 Circulating pump frequency: fP = fP0·(L / ∑Qp0)·K6 In the formula: fJ and fP are the real-time operating frequencies of the fan and circulating liquid pump, respectively, in Hz, with the rated frequency both taken as 50Hz; S is the cross-sectional area of ​​the spray tower, calibrated to 0.085m². 2 Qtail is the real-time flow rate of the tail gas after dry gasification, in m2. 3 / h, collected by the sensing layer; ∑Qp0 is the sum of the rated flow rates of the three circulating liquid pumps, calibrated to 2733kg / h; K5 and K6 are the flow rate correction coefficients for the fan and circulating liquid pump, respectively, calibrated to 0.98 and 0.95.

[0012] Preferably, the execution elements of the execution layer specifically include: Supporting components for dry gasification indicators: frequency converter for cooling capacity of cryogenic refrigerant unit, temperature regulating valve for cryogenic refrigerator, and electric valve for condensate discharge from gas-liquid separator. The components supporting the removal efficiency indicators are: fan frequency converter, three-stage circulating liquid pump frequency converter, chilled water flow electric regulating valve, and spray tower feed self-priming pump.

[0013] Preferably, the control layer also has a built-in closed-loop correction logic: the perception layer collects data of the two core control indicators in real time. If the NMP removal efficiency control indicator does not meet the standard, the frequency of the blower and circulating liquid pump is dynamically adjusted through the spray parameter comprehensive adjustment model until the removal efficiency is ≥99.99%, provided that the dry gasification indicator meets the standard.

[0014] Preferably, the control layer also has built-in auxiliary control logic: when the liquid level in the bottom of the three-stage spray tower is lower than 50mm, a quantitative feeding program is started to replenish the liquid level to 550mm; when a shutdown command is received, the shutdown process is executed in sequence as follows: stop the intake of exhaust gas → continue to run the cryogenic unit for 2 minutes → blower supply air for 5 minutes → shut down the spray unit → shut down the cryogenic unit → automatically drain the liquid.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention ensures stable and compliant NMP removal efficiency from the source by achieving consistent dry gasification performance under operating conditions. It addresses the shortcomings of existing technologies that optimize condensation but fail to fundamentally resolve droplet entrainment issues through precise control of dry gasification using a quantitative model. This lays a solid foundation for achieving NMP removal efficiency standards, ensuring stable NMP removal efficiency that meets environmental requirements. By using dry gasification as a pre-existing constraint and precisely controlling the removal efficiency, the invention guarantees that the NMP content in the exhaust gas is ≤1 mg / m³. 3 The compliance rate is 100%, solving the problem of emission concentration fluctuations and the inability to meet the 1mg / m³ standard in existing technologies. 3 The pain points of the industry due to stringent standards.

[0016] This invention employs a cryogenic-spray intelligent linkage system, ensuring seamless control throughout the entire process. It achieves dynamic linkage between the cryogenic condensation and dry gasification effect and the spray absorption parameters, overcoming the shortcomings of existing technologies where two units operate independently and control is disconnected. It can adjust spray parameters in real time based on fluctuations in the dry gasification effect, ensuring stable overall removal efficiency. The system is simple, reliable, highly industrially applicable, and energy-saving: it eliminates redundant measuring points, models, and actuators, resulting in a simple system structure, low equipment modification costs, convenient operation and maintenance, and adaptability to actual industrial operating needs. Furthermore, it optimizes operating parameters through a quantitative model, avoiding energy waste caused by excessive manual adjustments. Attached Figure Description

[0017] Figure 1 The system architecture diagram of the intelligent control system of the NMP exhaust gas treatment device provided by the present invention is shown.

[0018] Figure 2 This is a framework diagram of NMP exhaust gas treatment provided by the present invention.

[0019] Figure 3 The present invention provides a flowchart for NMP exhaust gas treatment. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figures 1-3 As shown, an intelligent control system for an NMP exhaust gas treatment device is disclosed. The NMP exhaust gas treatment device includes a cryogenic refrigerant unit, a cryogenic refrigerator, a gas-liquid separator, a surface cooler + demister, a three-stage spray tower, a fan, a circulating liquid pump, and a self-priming pump. The intelligent control system is characterized by adopting a three-level architecture of perception layer, control layer, and execution layer, and locking two core control indicators to achieve full-process quantitative closed-loop linkage control. The two core control indicators include: Cryogenic condensation and dry gasification control indicators: the dew point of the exhaust gas at the outlet of the gas-liquid separator (i.e., the inlet of the spray tower) is ≤10℃ and the content of micro-droplets is ≤0.01mg / m³. 3 ; NMP removal efficiency control target: The NMP removal efficiency of the tail gas at the outlet of the three-stage spray tower is ≥99.99%, corresponding to an NMP content of ≤1mg / m³ in the tail gas. 3 It is suitable for operating conditions with an inlet NMP concentration of 250~350ppm; The sensing layer is equipped with detection sensors that match the two core control indicators. The acquisition frequency is 2 seconds / time. These sensors are used to collect data on exhaust gas flow rate, exhaust gas inlet and outlet NMP concentration, cryogenic refrigerator inlet and outlet temperature, gas-liquid separator outlet dew point and micro-droplet content, spray tower empty tower gas velocity, circulating liquid total flow rate, spray tower inlet and outlet gas temperature, and tower bottom liquid level, and transmit the data to the control layer. The control layer is an industrial intelligent controller, which has four core mathematical control models that are coupled and linked: a cryogenic condensation temperature regulation model, a cryogenic refrigerant unit cooling capacity regulation model, an NMP removal efficiency core model, and a spray parameter comprehensive regulation model. It takes the achievement of dry gasification control indicators as a prerequisite constraint and the achievement of NMP removal efficiency control indicators as the final goal, calculates the optimal operating parameters and outputs control commands. The execution layer includes a cryogenic condensation execution unit and a spray absorption execution unit, with a response time of ≤1s. The cryogenic condensation execution unit is used to adjust the condensation temperature, cooling capacity, and condensate discharge, while the spray absorption execution unit is used to adjust the fan frequency, circulating liquid pump frequency, and chilled water flow rate, accurately executing the control layer commands.

[0022] The detection sensors in the perception layer specifically include: Supporting sensors for dry gasification indicators: dew point sensor at gas-liquid separator outlet, online micro-droplet detector, cryogenic refrigerator outlet temperature sensor, and condensate level sensor for gas-liquid separator. Sensors supporting the removal efficiency indicators: NMP concentration sensor at the spray tower inlet, NMP concentration sensor at the spray tower outlet, air velocity sensor in the spray tower empty tower, total flow rate sensor of circulating liquid, air temperature sensor at the spray tower inlet and outlet, and liquid level sensor at the bottom of the three-stage spray tower.

[0023] The calculation formula for the cryogenic condensation temperature regulation model is as follows: Tc = Td - K1·lg(Cd / Cd0) - K2·(Q tail / 2000) In the formula: Tc is the target condensing temperature at the outlet of the cryogenic refrigerator, in °C; Td is the dew point threshold of the dry vaporization index, taken as 10 °C; Cd is the droplet content threshold of the dry vaporization index, taken as 0.01 mg / m³. 3 Cd0 is the baseline value for droplet concentration, and the device is calibrated to 0.1 mg / m³. 3 Q represents the real-time exhaust gas flow rate, in meters per second (m³). 3 / h; K1 is the droplet-condensation temperature coupling coefficient, calibrated to 8.5; K2 is the flow rate-condensation temperature correction coefficient, calibrated to 2.3.

[0024] The calculation formula for the cooling capacity adjustment model of cryogenic refrigerant units is as follows: Q_cold = K3·(T_tail - T_c)·Q_tail·C In the formula: Qcold is the target cooling capacity of the cryogenic refrigerant unit, in kJ / h; Ttailin is the inlet exhaust gas temperature of the cryogenic refrigerator, in °C, collected by the sensing layer; K3 is the cooling efficiency correction coefficient, calibrated to 1.12; C is the isobaric specific heat capacity of the NMP exhaust gas, calibrated to 1.05 kJ / (m2). 3 ·℃).

[0025] The control layer has built-in pre-constraint logic: when the control index of cryogenic condensation dry gasification fails to meet the standard, the NMP removal efficiency regulation model is locked, the cryogenic condensation dry gasification regulation model is started first, and the control logic of the spray absorption unit is unlocked after the dry gasification index meets the standard.

[0026] The NMP removal efficiency core model only takes effect when the dry gasification index meets the standard, and its calculation formula is as follows: η = 1 - (K4·U1.2·C0.8) / (L1.5·(Tin - Tout)0.9) In the formula: η is the NMP removal efficiency, with a target threshold of ≥99.99%; U is the empty gas velocity of the spray tower, in m / s, ranging from 6.94 to 13.89 m / s; C is the NMP concentration of the circulating liquid in the first-stage spray tower, in %, ranging from 0 to 90%; L is the spray density, i.e., the total flow rate of the circulating liquid, in kg / h, ranging from 911 to 1823 kg / h; Tin / Tout are the inlet / outlet temperatures of the spray tower, with control targets of 13℃ / 10℃ respectively; K4 is the gas-liquid mass transfer coefficient after dry gasification meets the standard, calibrated to 0.023.

[0027] The integrated spray parameter regulation model includes a fan frequency regulation sub-model and a circulating liquid pump frequency regulation sub-model: Fan frequency: fJ = ​​fJ0·(U·S / Q tail stem)·K5 Circulating pump frequency: fP = fP0·(L / ∑Qp0)·K6 In the formula: fJ and fP are the real-time operating frequencies of the fan and circulating liquid pump, respectively, in Hz, with the rated frequency both taken as 50Hz; S is the cross-sectional area of ​​the spray tower, calibrated to 0.085m². 2 Qtail is the real-time flow rate of the tail gas after dry gasification, in m2. 3 / h, collected by the sensing layer; ∑Qp0 is the sum of the rated flow rates of the three circulating liquid pumps, calibrated to 2733kg / h; K5 and K6 are the flow rate correction coefficients for the fan and circulating liquid pump, respectively, calibrated to 0.98 and 0.95.

[0028] The execution elements of the execution layer specifically include: Supporting components for dry gasification indicators: frequency converter for cooling capacity of cryogenic refrigerant unit, temperature regulating valve for cryogenic refrigerator, and electric valve for condensate discharge from gas-liquid separator. The components supporting the removal efficiency indicators are: fan frequency converter, three-stage circulating liquid pump frequency converter, chilled water flow electric regulating valve, and spray tower feed self-priming pump.

[0029] The control layer also has a built-in closed-loop correction logic: the perception layer collects data on the two core control indicators in real time. If the NMP removal efficiency control indicator does not meet the standard, the frequency of the blower and circulating liquid pump is dynamically adjusted through the spray parameter comprehensive adjustment model, provided that the dry gasification indicator meets the standard, until the removal efficiency is ≥99.99%.

[0030] The control layer also has built-in auxiliary control logic: when the liquid level in the bottom of the three-stage spray tower is lower than 50mm, the quantitative feeding program is started to replenish the liquid level to 550mm; when a shutdown command is received, the shutdown process is executed in sequence: stop the exhaust gas intake → continue running the cryogenic unit for 2 minutes → blower supply air for 5 minutes → shut down the spray unit → shut down the cryogenic unit → automatically drain the liquid.

[0031] Example 1 Intelligent control implementation under basic operating conditions: Basic operating conditions for NMP tail gas treatment in industries such as lithium battery coating and electronic insulation material production. Specific parameters are: real-time flow rate of NMP tail gas at the inlet of the cryogenic cooler Q tail = 2000 cubic meters / hour, inlet tail gas temperature T tail in = 25℃, inlet NMP tail gas concentration 300ppm, ambient temperature 20℃; no operating condition fluctuations, initial value of the bottom liquid level of the tower is 0, and the initial NMP concentration of the circulating liquid is 0.

[0032] A tail gas flow sensor, a temperature sensor, and an NMP concentration sensor are installed at the inlet of the cryogenic refrigerator; a dew point sensor and a micro-droplet online detector are installed at the outlet of the gas-liquid separator; a temperature sensor and an empty tower gas velocity sensor are installed at the inlet and outlet of the three-stage spray tower, and a liquid level sensor is installed at the bottom of the spray tower; a flow sensor and an NMP concentration sensor are installed in the circulating liquid pipeline; all sensors are sampled at a frequency of 2 seconds / time, and the measurement accuracy meets the requirements for industrial waste gas treatment and detection, and the data can be transmitted to the control layer in real time.

[0033] The cryogenic refrigerant unit is equipped with a cooling capacity inverter; the cryogenic refrigerant outlet is equipped with a temperature regulating valve; and the bottom of the gas-liquid separator is equipped with a condensate discharge electric valve. The fan and the three-stage circulating liquid pump are each equipped with a frequency inverter; the refrigerant pipeline is equipped with an electric flow regulating valve; and the three-stage spray tower feed pipeline is equipped with a self-priming pump and an electric control valve. All actuators have a response time of ≤1s and can receive electrical signal commands from the control layer to complete parameter adjustment.

[0034] Electrically connect the industrial intelligent controller (PLC / DCS) to the sensing layer and execution layer, and import the cryogenic condensation dry gasification control model group (condensation temperature adjustment model, refrigeration capacity adjustment model) and NMP removal efficiency control model group (removal efficiency core model, spray parameter comprehensive adjustment model) of this invention; enter the above basic calibration parameters and core control thresholds; complete the equipment self-test, and reset all actuators to the off state; start the feed self-priming pump to replenish water to the bottom of the three-stage spray tower to the target liquid level of 550mm; start the cryogenic refrigerant unit and the low-temperature water generator unit to the preheating standby state.

[0035] The sensing layer collects operating condition data at the inlet of the cryogenic refrigerator and transmits it to the control layer. The control layer determines that the initial dew point at the outlet of the gas-liquid separator is 50℃ and the micro-droplet content is 0.05mg / m³. 3 If the dry gasification control indicators are not met, the cryogenic condensation dry gasification regulation model group will be activated.

[0036] The control layer uses Td=50℃, Cd=0.01mg / m3, Q tail=2000m3 / h, and substitutes them into the condensation temperature regulation model (1) to calculate Tc=56.2℃.

[0037] The control layer T tail is -50℃, Cd=0.01mg / m3, Q tail=2000m3 / h. Substituting these into the refrigeration capacity adjustment model (2), the target refrigeration capacity of the cryogenic refrigerant unit is calculated to be Q cold=-72902.4kJ / h, with the negative sign indicating refrigeration.

[0038] The control layer sends an electrical signal command to the execution layer: the frequency converter of the cryogenic refrigerant unit is adjusted to the corresponding power, outputting a cooling capacity of 72902.4 kJ / h; the opening of the cryogenic refrigerator temperature regulating valve is adjusted to 60%, cooling the exhaust gas to 56.2℃; since the condensate level in the gas-liquid separator tank has not risen significantly, the condensate discharge procedure is not initiated for the time being. 30 seconds after adjustment, the sensing layer feeds back the outlet data of the gas-liquid separator tank: dew point 48℃, micro-droplet content 0.008 mg / m³. 3 This meets the dry gasification control targets. The control layer sends a command to the execution layer to open the inlet valve from the gas-liquid separator to the three-stage spray tower, sending the dry gasified waste gas into the spray absorption unit.

[0039] After receiving the dry gasification compliance signal, the control layer unlocks the NMP removal efficiency control model group and substitutes the operating data after dry gasification into the NMP removal efficiency core model (3). With η≥99.9% as a constraint, the target empty tower gas velocity u=10.42m / s, the target spray density L=1519kg / h, and the target NMP concentration C=40% of the circulating liquid in the first-stage spray tower were obtained through iterative calculation and optimization. Substituting u=10.42m / s into the fan frequency regulation model (4), the calculated (after dry gasification, the tail gas flow rate does not change significantly) yields: f≈82.0Hz. The rated upper limit of the wind turbine frequency converter is 50Hz, which is adjusted to 45Hz according to the actual equipment adaptability, and the actual empty tower air velocity is accurately matched to 10.42m / s; Substituting L=1519kg / h into the circulating liquid pump frequency adjustment model (5), we calculate fp≈29.2Hz. The control layer evenly distributes 29.2Hz to the three-stage circulating liquid pumps, adjusts the frequency of each pump to 29Hz, and precisely controls the total flow rate of the circulating liquid to 1519kg / h, ensuring that the spray density meets the standard. The sensing layer collects the initial air temperature of the spray tower as 22℃, which deviates from the target value by 13℃. The control layer sends a command to the electric regulating valve of chilled water flow, adjusting the opening to 80% and the chilled water flow to 3780kg / h, cooling the air temperature of the spray tower to 13℃, and simultaneously controlling the air temperature at 10℃. The sensing layer detects that the initial NMP concentration of the circulating liquid in the first-stage spray tower is 0. The control layer issues an instruction according to the target value of 40% to add new NMP liquid to the tower bottom through a metering pump until the concentration reaches 40%, at which point the addition stops.

[0040] The sensing layer collects core indicator data every 2 seconds and transmits it to the control layer; the dew point at the outlet of the gas-liquid separator is 48–49℃, and the concentration of minute droplets is 0.007–0.008 mg / m³. 3 (Dry gasification continues to meet standards), the empty tower gas velocity of the spray tower is 10.42±0.02m / s, the circulating liquid flow rate is 1519±5kg / h, the spray tower inlet temperature is 13±0.1℃, and the outlet temperature is 10±0.1℃; The control layer calculates the removal efficiency in real time based on the NMP concentrations at the inlet and outlet of the spray tower: η = 99.95%; The system ran continuously and stably for 8 hours without any parameters exceeding the standard. The core indicators are as follows: ① Dry gasification indicators: dew point 48~49℃, micro-droplets 0.007~0.008mg / m³ 3 ① The compliance rate is 100%; ② NMP removal efficiency: 99.94%~99.95%, and the NMP content at the exhaust gas outlet is 0.7~0.8 mg / m³. 3 The concentration was below 1 mg / m3, achieving a compliance rate of 100%. Inlet NMP concentration 300ppm, exhaust gas flow rate 2000m³ / h 3 Under the basic operating conditions of / h, the system completed 72 hours of continuous uninterrupted operation verification. No human intervention was required throughout the entire process, and core indicators remained consistently within acceptable limits with no parameters exceeding the acceptable range. The dew point remained stable at 48–49℃, and the micro-droplet concentration remained stable at 0.007–0.008 mg / m³. 3, no fluctuation, compliance rate 100%; the overall η is stably maintained at 99.94%~99.95%, and the NMP content at the tail gas outlet is stably maintained at 0.7~0.8mg / m 3 , no excess, compliance rate 100%; the fan frequency is 45Hz, the single circulating liquid pump frequency is 29Hz, the chilled water flow rate is 3780kg / h, no adjustment is made throughout the process, and the equipment has no faults.

[0041] Embodiment 2 On the basis of the above embodiment, intelligent linkage control under tail gas flow fluctuation conditions: the speed of the lithium battery coating production line is increased, and the NMP tail gas flow rises to 2200m 3 / h, the inlet temperature rises to 27℃, in the initial state, the dew point at the outlet of the gas-liquid separation tank rises to 13℃, and the micro-droplet content is 0.012mg / m 3 , and the NMP removal efficiency drops to 99.7%.

[0042] After the perception layer detects the fluctuation, the control layer locks the removal efficiency regulation model, and prioritizes adjusting the dry gasification index: the new target condensing temperature Tc=9.4℃ is calculated, the target refrigeration capacity is increased to 44131.2kJ / h, the execution layer increases the power of the chiller unit by 15%, opens the condensate discharge valve for 2s to discharge liquid, and the dry gasification index meets the standard again after 25s. After unlocking the removal efficiency model, the spraying parameters are recalculated, the fan frequency is adjusted to 42Hz, the single circulating liquid pump frequency is adjusted to 31Hz, the chilled water flow rate is increased to 4100kg / h, the system returns to stability after 60s, the NMP removal efficiency rises back to 99.91%~99.93%, and the NMP content at the tail gas outlet is 0.8~0.9mg / m 3 , no excess occurs throughout the process.

[0043] On the basis of the above embodiment, the intelligent control implementation under the molecular sieve drying test condition can also be carried out: This embodiment is a special working condition for the molecular sieve drying test supporting NMP tail gas treatment, which is applicable to industrial scenarios with higher requirements for tail gas dryness, and the additional parameters on the basis of the basic working condition of Embodiment 1 are: A molecular sieve drying tube (diameter 32mm) is installed at the outlet of the three-stage spray tower, and the test target is to precisely control the dew point of the tail gas at the outlet of the drying tube to 50℃; the dry gasification control index, the NMP removal efficiency control index and other basic calibration parameters are consistent with those in Embodiment 1.

[0044] The deep cooling condensation dry gasification control is completed according to the steps of Embodiment 1, so that the dew point at the outlet of the gas-liquid separation tank is 48℃, and the micro-droplet content is 0.008mg / m 3 , and the dry gasification control index meets the standard.

[0045] The control layer activates the molecular sieve drying tube dew point linkage control module, which links the target dew point value of 50℃ at the outlet of the drying tube with the target condensation temperature of the cryogenic condenser, and finely adjusts the target condensation temperature at the outlet of the cryogenic refrigerator from 56.2℃ to 56.5℃ to ensure that the dew point of the exhaust gas at the outlet of the spray tower matches the requirements of the drying test.

[0046] The control layer adjusts the fan frequency to precisely control the gas velocity inside the molecular sieve drying tube to 10.42 m / s, which is consistent with the gas velocity in the empty tower of the spray tower; dew point sensors are installed at the inlet and outlet of the drying tube to collect drying effect data in real time and transmit it to the control layer.

[0047] The spray absorption unit was operated according to the optimal operating parameters of Example 1, maintaining an empty tower gas velocity of 10.42 m / s, a spray density of 1519 kg / h, an inlet temperature of 13°C and an outlet temperature of 10°C, and a circulating liquid NMP concentration of 40%, to ensure that the NMP removal efficiency control indicators were stably met.

[0048] Based on real-time dew point data at the inlet and outlet of the drying pipe, the control layer adjusts the cooling capacity slightly through the cryogenic refrigerant unit to precisely control the dew point at the outlet of the drying pipe at 50±0.5℃. After the system has been running stably for 1 hour, multiple sampling and testing are conducted at the inlet and outlet of the drying pipe and the outlet of the spray tower in accordance with industrial waste gas sampling standards.

[0049] The control indicators for dry gasification at the outlet of the gas-liquid separator and the NMP removal efficiency at the outlet of the spray tower were consistent with those in Example 1, achieving a 100% compliance rate. The dew point at the outlet of the molecular sieve drying tube was precisely controlled between 49.5 and 50.5°C, and the NMP content in the tail gas after drying was reduced to 0.4–5 mg / m³. 3 The NMP removal efficiency was increased to 99.97%–99.98%. The relative error of the sampling and detection data is ≤ ±0.05 mg / m³. 3 .

[0050] Example 3 Based on the above embodiments, intelligent control implementation under conditions of fluctuating inlet NMP concentration is also included: This experiment was divided into two sub-conditions: the lower concentration limit condition (250 ppm) and the upper concentration limit condition (350 ppm). Based on the basic steady-state condition of Example 1, only the initial concentration of NMP exhaust gas at the inlet of the cryogenic refrigerator was changed. The remaining basic parameters were: exhaust gas flow rate 2000 m³ / h. 3 / h, inlet exhaust gas temperature 25℃, ambient temperature 20℃ remain constant; The core control thresholds are consistent with those in Example 1. Dry vaporization parameters (dew point ≤ 50℃, micro-droplets ≤ 0.01 mg / m³) 3 NMP removal efficiency ≥99.96% (corresponding to NMP content in exhaust gas ≤1mg / m³) 3Simultaneously, under the basic operating condition of a concentration of 300ppm, a 72-hour long-term continuous operation verification was completed, and the model basis for fan frequency correction and cooling capacity numerical definition in Example 1 was supplemented.

[0051] The sensing layer collects initial operating condition data and transmits it to the control layer, determining that the initial dew point at the outlet of the gas-liquid separator is 50℃ and the micro-droplet content is 0.05mg / m³. 3 The dry gasification index was not met, so the dry gasification control model group was activated. The control layer was set to Td=50℃ and Cd=0.01mg / m³. 3 Q tail = 2000m 3 Substituting / h into the condensing temperature regulation model (1), the target condensing temperature Tc = 56.2℃ was calculated; with T_tail = 25℃, Tc = 56.2℃, and Q_tail = 2000m 3 Substituting / h into the cooling capacity adjustment model (2), the target cooling capacity Q_cooling = -72902.4kJ / h is calculated (the negative sign indicates that the refrigeration unit performs refrigeration operation on the exhaust gas, the absolute value of the cooling capacity is 72902.4kJ / h, which is unrelated to the exhaust gas concentration and is only determined by the flow rate and temperature); the execution layer adjusts according to the command: the cooling capacity output of the cryogenic refrigerant unit is 72902.4kJ / h, the opening degree of the cryogenic refrigerator temperature regulating valve is 60%, and the sensing layer feeds back the data after 30s: dew point 48℃, micro-droplet content 0.007mg / m 3 The dry gasification indicators meet the standards, and the waste gas is sent into the spray absorption unit.

[0052] After receiving the dry gasification compliance signal, the control layer unlocks the removal efficiency control model group, substitutes the inlet NMP concentration of 250ppm and the working condition data after dry gasification into the core model of removal efficiency (3), and uses η≥99.96% as a constraint to iteratively calculate and optimize the target parameters, the target empty tower gas velocity u=11.2m / s, the target spray density L=1420kg / h, and the target value of NMP concentration of the circulating liquid in the first-stage spray tower C=35%; Substituting u=11.2m / s into model (4), the theoretical fan frequency fJ≈88.5Hz was calculated. Combined with the rated upper limit of 50Hz for the fan, the fan frequency-tower air velocity linear coupling correction model was used to adjust the actual fan frequency to 47Hz, and the actual tower air velocity was accurately matched to 11.2m / s. Substituting L=1420kg / h into model (5), we calculate fP≈27.3Hz, which is evenly distributed to the three-stage circulating liquid pump. The frequency of each pump is adjusted to 27Hz, and the total flow rate of the circulating liquid is precisely controlled to 1420kg / h. With the chilled water flow regulating valve opened at 75%, the inlet air temperature of the spray tower was cooled to 13℃ and the outlet air temperature to 10℃; new NMP solution was added through a metering pump to adjust the circulating liquid concentration to 35%.

[0053] The system operated continuously and stably for 4 hours, with the sensing layer collecting data in real time every 2 seconds. Key performance indicators met the following standards: dew point 48–49℃, and micro-droplet concentration 0.006–0.007 mg / m³. 3 The compliance rate was 100%; η = 99.97%~99.98%, and the NMP content at the exhaust outlet was 0.5~0.6 mg / m³. 3 Not higher than 1 mg / m 3 The compliance rate was 100%.

[0054] The sensing layer collects initial operating condition data and determines the initial dew point at the outlet of the gas-liquid separator to be 50℃ and the micro-droplet content to be 0.05mg / m³. 3 The dry gasification index was not met, so the dry gasification control model group was activated. The dry gasification control parameters were completely consistent with the lower limit concentration condition. The control layer calculated the target condensing temperature Tc = 56.2℃ and the target cooling capacity Q_cooling = -72902.4kJ / h. 30 seconds after the execution layer adjusted, the sensing layer reported a dew point of 48℃ and a micro-droplet content of 0.008mg / m³. 3 The dry gasification indicators meet the standards.

[0055] The control layer unlocks the removal efficiency regulation model group, and substitutes the inlet NMP concentration of 350ppm and the working condition data after dry gasification into the model (3). With η≥99.96% as a constraint, the target parameters are obtained by iterative calculation and optimization. The target empty tower gas velocity u=9.8m / s, the target spray density L=1600kg / h, and the target value of the NMP concentration of the circulating liquid in the first-stage spray tower C=45%; Substituting u=9.8m / s into model (4), the theoretical wind turbine frequency fJ≈77.2Hz was calculated. After correction according to the model, the actual frequency was adjusted to 43Hz to accurately match the target empty tower air velocity of 9.8m / s. Substituting L=1600kg / h into model (5), we calculate fP≈30.8Hz, which is evenly distributed to the three-stage circulating liquid pump. The frequency of each pump is adjusted to 31Hz, and the total flow rate of the circulating liquid is precisely controlled to 1600kg / h.

[0056] With the chilled water flow regulating valve opened at 85%, the inlet air temperature of the spray tower was cooled to 13℃ and the outlet air temperature to 10℃; new NMP solution was added through a metering pump to adjust the circulating liquid concentration to 45%.

[0057] The system ran continuously and stably for 4 hours, with the perception layer collecting data every 2 seconds in real time to monitor the compliance of key indicators. Dew point 48–49℃, droplet density 0.007–0.008 mg / m³ 3 The compliance rate was 100%; η = 99.96%~99.97%, and the NMP content at the exhaust outlet was 0.9~1.0 mg / m³. 3 Not higher than 1 mg / m 3The compliance rate was 100%.

[0058] Working Principle: This intelligent control system is built upon an NMP exhaust gas treatment device based on cryogenic condensation and three-stage spray absorption. It adopts a three-tiered architecture of "sensing layer - control layer - execution layer." The core is to lock in two key control indicators as the basis for full-process control. The control layer incorporates a coupled control model based on these two key indicators. The three layers work together to achieve intelligent operation of the device. The sensing layer is the core control indicator detection unit, equipped with sensors directly related to the two core control indicators, collecting data at a frequency of 2 seconds per acquisition to ensure data accuracy and simple detection logic, providing reliable input to the control layer. The control layer is the core control indicator coupled calculation unit, incorporating four basic mathematical control models. These models are coupled and linked, using the achievement of dry gasification control indicators as a prerequisite constraint and the achievement of NMP removal efficiency control indicators as the ultimate goal, quantifying and calculating operating parameters and outputting instructions. The execution layer is the core control indicator precision execution unit, configured with actuators directly related to the two core control indicators, with a response time ≤1 second, ensuring accurate implementation of control commands.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An intelligent control system for an NMP exhaust gas treatment device, the NMP exhaust gas treatment device comprising a cryogenic refrigerant unit, a cryogenic refrigerator, a gas-liquid separator, a surface cooler + demister, a three-stage spray tower, a fan, a circulating liquid pump, and a self-priming pump, characterized in that, The intelligent control system adopts a three-level architecture of perception layer, control layer and execution layer, and locks two core control indicators to achieve full-process quantitative closed-loop linkage control; The two core control indicators include: Cryogenic condensation and dry gasification control indicators: the dew point of the exhaust gas at the outlet of the gas-liquid separator (i.e., the inlet of the spray tower) is ≤10℃ and the content of micro-droplets is ≤0.01mg / m³. 3 ; NMP removal efficiency control target: The NMP removal efficiency of the tail gas at the outlet of the three-stage spray tower is ≥99.99%, corresponding to an NMP content of ≤1mg / m³ in the tail gas. 3 It is suitable for operating conditions with an inlet NMP concentration of 250-350 ppm; The sensing layer is equipped with detection sensors that match the two core control indicators. The acquisition frequency is 2 seconds / time. These sensors are used to collect data on exhaust gas flow rate, exhaust gas inlet and outlet NMP concentration, cryogenic refrigerator inlet and outlet temperature, gas-liquid separator outlet dew point and micro-droplet content, spray tower empty tower gas velocity, circulating liquid total flow rate, spray tower inlet and outlet gas temperature, and tower bottom liquid level, and transmit the data to the control layer. The control layer is an industrial intelligent controller, which has four core mathematical control models that are coupled and linked: a cryogenic condensation temperature regulation model, a cryogenic refrigerant unit cooling capacity regulation model, an NMP removal efficiency core model, and a spray parameter comprehensive regulation model. It takes the achievement of dry gasification control indicators as a prerequisite constraint and the achievement of NMP removal efficiency control indicators as the final goal, calculates the optimal operating parameters and outputs control commands. The execution layer includes a cryogenic condensation execution unit and a spray absorption execution unit, with a response time of ≤1s. The cryogenic condensation execution unit is used to adjust the condensation temperature, cooling capacity, and condensate discharge, while the spray absorption execution unit is used to adjust the fan frequency, circulating liquid pump frequency, and chilled water flow rate, accurately executing the control layer commands.

2. The intelligent control system of the NMP exhaust gas treatment device according to claim 1, characterized in that, The detection sensors in the sensing layer specifically include: Supporting sensors for dry gasification indicators: dew point sensor at gas-liquid separator outlet, online micro-droplet detector, cryogenic refrigerator outlet temperature sensor, and condensate level sensor for gas-liquid separator. Sensors supporting the removal efficiency indicators: NMP concentration sensor at the spray tower inlet, NMP concentration sensor at the spray tower outlet, air velocity sensor in the spray tower empty tower, total flow rate sensor of circulating liquid, air temperature sensor at the spray tower inlet and outlet, and liquid level sensor at the bottom of the three-stage spray tower.

3. The intelligent control system for an NMP exhaust gas treatment device according to claim 1, characterized in that, The calculation formula for the cryogenic condensation temperature regulation model is as follows: Tc = Td - K1·lg(Cd / Cd0) - K2·(Q tail / 2000) In the formula: Tc is the target condensing temperature at the outlet of the cryogenic refrigerator, in °C; Td is the dew point threshold of the dry vaporization index, taken as 10 °C; Cd is the droplet content threshold of the dry vaporization index, taken as 0.01 mg / m³. 3 Cd0 is the baseline value for droplet concentration, and the device is calibrated to 0.1 mg / m³. 3 Q represents the real-time exhaust gas flow rate, in meters per second (m³). 3 / h; K1 is the droplet-condensation temperature coupling coefficient, calibrated to 8.5; K2 is the flow rate-condensation temperature correction coefficient, calibrated to 2.

3.

4. The intelligent control system of the NMP exhaust gas treatment device according to claim 3, characterized in that, The calculation formula for the cooling capacity adjustment model of the cryogenic refrigerant unit is as follows: Q_cold = K3·(T_tail - T_c)·Q_tail·C In the formula: Qcold is the target cooling capacity of the cryogenic refrigerant unit, in kJ / h; Ttailin is the inlet exhaust gas temperature of the cryogenic refrigerator, in °C, collected by the sensing layer; K3 is the cooling efficiency correction coefficient, calibrated to 1.12; C is the isobaric specific heat capacity of the NMP exhaust gas, calibrated to 1.05 kJ / (m2). 3 ·℃).

5. The intelligent control system of the NMP exhaust gas treatment device according to claim 1, characterized in that, The control layer has built-in pre-constraint logic: when the control index of cryogenic condensation dry gasification fails to meet the standard, the NMP removal efficiency regulation model is locked, the cryogenic condensation dry gasification regulation model is started first, and the control logic of the spray absorption unit is unlocked only after the dry gasification index meets the standard.

6. The intelligent control system of the NMP exhaust gas treatment device according to claim 5, characterized in that, The NMP removal efficiency core model only takes effect when the dry gasification index meets the standard, and its calculation formula is as follows: η = 1 - (K4·U1.2·C0.8) / (L1.5·(Tin - Tout)0.9) In the formula: η is the NMP removal efficiency, with a target threshold of ≥99.99%; U is the empty gas velocity of the spray tower, in m / s, ranging from 6.94 to 13.89 m / s; C is the NMP concentration of the circulating liquid in the first-stage spray tower, in %, ranging from 0 to 90%; L is the spray density, i.e., the total flow rate of the circulating liquid, in kg / h, ranging from 911 to 1823 kg / h; Tin / Tout are the inlet / outlet temperatures of the spray tower, with control targets of 13℃ / 10℃ respectively; K4 is the gas-liquid mass transfer coefficient after dry gasification meets the standard, calibrated to 0.

023.

7. The intelligent control system of the NMP exhaust gas treatment device according to claim 6, characterized in that, The comprehensive spray parameter adjustment model includes a fan frequency adjustment sub-model and a circulating liquid pump frequency adjustment sub-model: Fan frequency: fJ = ​​fJ0·(U·S / Q tail stem)·K5 Circulating pump frequency: fP = fP0·(L / ∑Qp0)·K6 In the formula: fJ and fP are the real-time operating frequencies of the fan and circulating liquid pump, respectively, in Hz, with the rated frequency both taken as 50Hz; S is the cross-sectional area of ​​the spray tower, calibrated to 0.085m². 2 Qtail is the real-time flow rate of the tail gas after dry gasification, in m2. 3 / h, collected by the sensing layer; ∑Qp0 is the sum of the rated flow rates of the three circulating liquid pumps, calibrated to 2733kg / h; K5 and K6 are the flow rate correction coefficients for the fan and circulating liquid pump, respectively, calibrated to 0.98 and 0.

95.

8. The intelligent control system of the NMP exhaust gas treatment device according to claim 1, characterized in that, The execution elements of the execution layer specifically include: Supporting components for dry gasification indicators: frequency converter for cooling capacity of cryogenic refrigerant unit, temperature regulating valve for cryogenic refrigerator, and electric valve for condensate discharge from gas-liquid separator. The components supporting the removal efficiency indicators are: fan frequency converter, three-stage circulating liquid pump frequency converter, chilled water flow electric regulating valve, and spray tower feed self-priming pump.

9. The intelligent control system of the NMP exhaust gas treatment device according to claim 1, characterized in that, The control layer also has a built-in closed-loop correction logic: the perception layer collects data on the two core control indicators in real time. If the NMP removal efficiency control indicator does not meet the standard, the frequency of the blower and circulating liquid pump is dynamically adjusted through the spray parameter comprehensive adjustment model, provided that the dry gasification indicator meets the standard, until the removal efficiency is ≥99.99%.

10. The intelligent control system of the NMP exhaust gas treatment device according to claim 1, characterized in that, The control layer also has built-in auxiliary control logic: when the liquid level in the bottom of the three-stage spray tower is lower than 50mm, a quantitative feeding program is started to replenish the liquid level to 550mm; when a shutdown command is received, the shutdown process is executed in sequence as follows: stop the exhaust gas intake → continue running the cryogenic unit for 2 minutes → blower supply air for 5 minutes → shut down the spray unit → shut down the cryogenic unit → automatically drain the liquid.

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