Pressurizing and mixing system in closed cavity

Abstract

The invention provides a pressurized mixing system in a closed cavity, and relates to the technical field of material mixing, the pressurized mixing system comprises a closed mixing device, a fluid injection system, a multi-parameter detection system and a control system, the closed mixing device is used for accommodating raw materials in various forms and realizing pressurized mixing; the fluid injection system is communicated with the closed mixing device and is used for injecting working fluid to adjust the rheological property of the material; the multi-parameter detection system is used for acquiring process parameters in the closed mixing device in real time; the control system is based on detection parameters, and a decoupling control algorithm and a multivariable coupling model are adopted; through the design of the closed mixing cavity, the whole-process closed processing of powder and liquid raw materials is realized, a supercritical fluid injection technology is combined, the loss rate of the raw materials is reduced to be less than 3%, the emission of volatile substances is completely eradicated, the environmental pollution risk is remarkably reduced, the environment is closed, meanwhile, oxygen contact is avoided, and the device is suitable for stable mixing of oxidizable materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material mixing, in particular to a pressurized mixing system in a closed cavity. BACKGROUND

[0002] When processing powder and liquid raw materials, the traditional mixing system has problems such as powder flying and liquid volatilization due to insufficient cavity sealing, resulting in a raw material loss rate of more than 15%, and environmental pollution caused by volatile organic emissions. In addition, the dispersion uniformity of high-viscosity materials depends on manual experience, and it is difficult to accurately determine the mixing endpoint in real time through viscosity detection, which may cause material agglomeration or over-mixing problems.

[0003] In addition, in the pressurization process of the existing mixing equipment, the material temperature rises out of control due to the increase in pressure, which may cause material degradation or equipment overload. The traditional single-variable control mode cannot solve the problem of multi-parameter coupling interference, resulting in low production continuity, frequent manual intervention, low product qualification rate, and difficulty in meeting the process requirements of high-end film products. Therefore, the present application proposes a pressurized mixing system in a closed cavity to solve the problems in the prior art. SUMMARY

[0004] To solve the above problems, the present application proposes a pressurized mixing system in a closed cavity. The pressurized mixing system in a closed cavity realizes closed processing of powder and liquid raw materials through the design of a closed mixing cavity, reduces the raw material loss rate to below 3% by combining supercritical fluid injection technology, completely eliminates volatile substance emissions, significantly reduces the risk of environmental pollution, and avoids oxygen contact in a closed environment, which is suitable for stable mixing of easily oxidized materials.

[0005] To achieve the purpose of the present application, the present application realizes the following technical solutions: a pressurized mixing system in a closed cavity, comprising a closed mixing device, a fluid injection system, a multi-parameter detection system, and a control system. The closed mixing device is used to accommodate raw materials in various forms and realize pressurized mixing. The fluid injection system is in communication with the closed mixing device and is used to inject working fluid to adjust the rheological properties of the materials.

[0006] The multi-parameter detection system is used to obtain process parameters inside the closed mixing device in real time. The control system dynamically controls the mixing process based on the detection parameters through a decoupling control algorithm and a multi-variable coupling model. The closed mixing device, the fluid injection system, the multi-parameter detection system, and the control system work cooperatively through signal and material transmission paths to form a closed-loop control architecture.

[0007] Further improvement lies in that the closed mixing device comprises a pressure-resistant cavity, a stirring assembly, a feeding port, a discharging port and an exhaust valve, the pressure-resistant cavity adopts a double jacket structure, the inner layer is made of 316L stainless steel, and the outer layer is a heat preservation layer; the stirring assembly is arranged in the cavity and is driven by a variable frequency motor, and the stirring speed ranges from 0 to 1200 rpm; the feeding port and the discharging port are used for feeding and discharging raw materials, and the exhaust valve is connected with a vacuum pump and is used for air extraction.

[0008] Further improvement lies in that the fluid injection system comprises a fluid storage tank and a booster pump, the fluid storage tank is used for containing supercritical fluid, and the booster pump is used for adjusting the fluid injection amount according to the instruction of a control system, and the accuracy of the flow meter is ±1%.

[0009] Further improvement lies in that the supercritical fluid is CO2, the injection amount ranges from 0 to 10 kg / h, the stirring speed is set to 400-800 rpm, the temperature control range is 120-180℃, and the pressure control range is 2-4 MPa.

[0010] Further improvement lies in that the multi-parameter detection system comprises a pressure detection unit, a temperature detection unit, a concentration detection unit and a dielectric constant detection unit, the pressure detection unit adopts a piezoresistive sensor, and the range is 0-5 MPa; the temperature detection unit adopts a platinum resistance sensor, and the accuracy is ±0.5℃; the concentration detection unit adopts a laser scattering method, and the response time is ≤1s; and the dielectric constant detection unit comprises parallel plate electrodes and an impedance analyzer, and the distance between the parallel plate electrodes is 10-20 mm.

[0011] Further improvement lies in that the dielectric constant detection unit converts the measured dielectric constant into a uniformity index UI, and when UI≥95%, it is determined that the mixing is uniform, and the UI calculation formula is:

[0012]

[0013] In the formula, εreal is the measured dielectric constant, and εideal is the theoretical uniform dielectric constant.

[0014] Further improvement lies in that the control system comprises an industrial computer and an actuator, the industrial computer is built-in with a decoupling control algorithm and a multivariable PID control model; and the actuator comprises a variable frequency motor, a heating element and a booster pump, and is used for regulating and controlling the mixing process.

[0015] Further improvement lies in that the decoupling control algorithm realizes parameter decoupling by the following formula:

[0016] Q=α·ΔP+β·ΔT+γ·ΔN

[0017] In the formula, Q is a comprehensive control amount, ΔP is a pressure deviation, ΔT is a temperature deviation, ΔN is a concentration deviation, and a, β, and γ are weight coefficients satisfying a+β+γ=1.

[0018] Further improvements are that the multivariable PID control model is coupled by the following dynamic parameters:

[0019]

[0020] In the formula, e(t) is an error vector of a set value and a measured value, including temperature (T), pressure (P), and concentration (N) parameters, K p , K i , and K d are proportional, integral, and differential coefficients satisfying K p :K i :K d =1.2:0.5:0.3.

[0021] Further improvements are that the weight coefficients are a=0.6, β=0.3, and γ=0.1, which are optimized by experiments; and the allowable deviation range of the error vector e(t) is T set value ±2℃, P set value ±0.1 MPa, and N set value ±1%.

[0022] The present application has the following beneficial effects:

[0023] 1. The present application realizes the whole-process closed processing of powder and liquid raw materials by the design of a closed mixing cavity, reduces the raw material loss rate to below 3% in combination with the supercritical fluid injection technology, completely eliminates the emission of volatile substances, significantly reduces the environmental pollution risk, and avoids the contact with oxygen in a closed environment, thereby being suitable for the stable mixing of easily oxidized materials.

[0024] 2. The present application adopts the dielectric constant real-time feedback mixing uniformity technology, improves the material uniformity index to above 98% through the linkage of parallel plate electrodes and an impedance analyzer, replaces the traditional subjective experience judgment, combines the supercritical fluid viscosity reduction technology, efficiently solves the dispersion problem of high-viscosity materials, and shortens the mixing time.

[0025] 3. The present application adopts the pressure-temperature decoupling control algorithm and the multivariable PID model, realizes the dynamic and accurate control of temperature, pressure, and concentration, improves the product qualification rate to above 99%, integrates the above-mentioned technologies in a closed-loop control system, forms an automatic production framework, reduces the manual operation intensity, and is suitable for the continuous production of various film products. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a front view of the present application. DETAILED DESCRIPTION

[0027] In order to deepen the understanding of the present application, the present application will be further described below in conjunction with examples, which are only used to explain the present application and do not constitute a limitation on the scope of protection of the present application.

[0028] Example one

[0029] According to Figure 1 As shown in the figure, the present embodiment proposes a pressurized mixing system in a closed cavity, including a closed mixing device, a fluid injection system, a multi-parameter detection system, a control system, the closed mixing device is used to accommodate various forms of raw materials and realize pressurized mixing; the fluid injection system is in communication with the closed mixing device, and is used to inject working fluid to adjust the rheological properties of the material flow;

[0030] The multi-parameter detection system is used to obtain the process parameters inside the closed mixing device in real time; the control system dynamically regulates and controls the mixing process based on the detection parameters through a decoupling control algorithm and a multi-variable coupling model; the closed mixing device, the fluid injection system, the multi-parameter detection system and the control system work cooperatively through the signal and material transmission path to form a closed-loop control architecture.

[0031] The closed mixing device includes a pressure-resistant cavity, a stirring assembly, a feeding port, a discharging port and an exhaust valve, the pressure-resistant cavity adopts a double-layer jacket structure, the inner layer is made of 316L stainless steel, and the outer layer is a heat preservation layer; the stirring assembly is arranged inside the cavity and is driven by a variable frequency motor, and the stirring speed range is 0-1200rpm; the feeding port and the discharging port are used for feeding and discharging raw materials, and the exhaust valve is connected with a vacuum pump and is used for air exhaust. Through the design of the closed mixing cavity, the whole process of the powder and liquid raw materials is closed, combined with the supercritical fluid injection technology, the raw material loss rate is reduced to below 3%, and the emission of volatile substances is completely eliminated, the environmental pollution risk is significantly reduced, and the closed environment avoids the contact with oxygen, which is suitable for the stable mixing of easily oxidized materials.

[0032] The fluid injection system includes a fluid storage tank, a booster pump and a flowmeter, the fluid storage tank is used to store supercritical fluid; the booster pump is used to adjust the fluid injection amount according to the instruction of the control system, and the accuracy of the flowmeter is ±1%. The supercritical fluid is CO2, the injection amount range is 0-10kg / h, the stirring speed is set to 400-800rpm, the temperature control range is 120-180℃, and the pressure control range is 2-4MPa.

[0033] The multi-parameter detection system comprises a pressure detection unit, a temperature detection unit, a concentration detection unit and a dielectric constant detection unit, the pressure detection unit adopts a piezoresistive sensor, the range is 0-5 MPa; the temperature detection unit adopts a platinum resistance sensor, the accuracy is ±0.5℃; the concentration detection unit adopts a laser scattering method, the response time is ≤1s; the dielectric constant detection unit comprises parallel plate electrodes and an impedance analyzer, the distance between the parallel plate electrodes is 10-20mm. The dielectric constant real-time feedback mixing uniformity technology is adopted, the parallel plate electrodes and the impedance analyzer are linked, the material uniformity quantitative index is improved to more than 98%, the traditional subjective experience judgment is replaced, the supercritical fluid viscosity reduction technology is combined, the high-viscosity material dispersion problem is efficiently solved, and the mixing time is shortened.

[0034] The dielectric constant detection unit converts the measured dielectric constant into a uniformity index UI, and when UI≥95%, it is determined that the mixing is uniform, and the UI calculation formula is:

[0035]

[0036] In the formula, εreal is the measured dielectric constant, and εideal is the theoretical uniform dielectric constant.

[0037] The control system comprises an industrial computer and an actuator, the industrial computer is built-in decoupling control algorithm and multivariable PID control model; the actuator comprises a variable frequency motor, a heating element and a booster pump, and is used for regulating and controlling the mixing process. The decoupling control algorithm realizes parameter decoupling by the following:

[0038] Q=α·ΔP+β·ΔT+γ·ΔN

[0039] In the formula, Q is a comprehensive control quantity, ΔP is a pressure deviation, ΔT is a temperature deviation, ΔN is a concentration deviation, α, β and γ are weight coefficients, and α+β+γ=1.

[0040] The multivariable PID control model couples parameters by the following:

[0041]

[0042] In the formula, e(t) is an error vector of a set value and a measured value, contains temperature (T), pressure (P) and concentration (N) parameters, K p , K i and K d are proportional, integral and differential coefficients, and K p :K i :K d= 1.2:0.5:0.3. The weight coefficients a = 0.6, b = 0.3, g = 0.1 are calibrated and optimized by experiments; the allowable deviation range of the error vector e(t) is: T set value ± 2℃, P set value ± 0.1 MPa, N set value ± 1%. The pressure-temperature decoupling control algorithm and the multivariable PID model are used to realize dynamic and accurate control of temperature, pressure and concentration, and the product qualified rate is increased to more than 99%. The closed-loop control system integrates the above technologies to form an automatic production architecture, reduces the intensity of manual operation, and is suitable for continuous production of various film products.

[0043] Example Two

[0044] According to Figure 1 The embodiment proposes a pressurized mixing system in a closed cavity for plastic film product production as shown in the figure:

[0045] The closed cavity is made of 316L stainless steel with a volume of 100L and a screw stirring paddle speed of 0-1000rpm adjustable;

[0046] The supercritical CO2 storage tank pressure is 8MPa, which is injected into the cavity through a booster pump, and the flow meter controls the injection amount of 5kg / h;

[0047] In the dielectric constant detection module, the parallel plate electrode spacing is 10mm, and the impedance analyzer frequency is 1MHz;

[0048] In the multi-parameter detection module, the pressure sensor range is 0-5MPa, the temperature sensor accuracy is ±0.5℃, and the concentration sensor response time is 1s;

[0049] The control system sets T = 150℃, P = 3MPa, N = 40%, adjusts the heating power and stirring speed through the formula, and the temperature fluctuation is actually measured ±1.8℃, and the mixing uniformity is 98.5%.

[0050] Example Three

[0051] According to Figure 1 The embodiment proposes a pressurized mixing system in a closed cavity for rubber film product production as shown in the figure:

[0052] The closed cavity is made of Hastelloy with a volume of 200L and a screw stirring paddle speed of 0-1200rpm adjustable;

[0053] The supercritical CO2 storage tank pressure is 10MPa, which is injected into the cavity through a booster pump, and the flow meter controls the injection amount of 4kg / h;

[0054] In the dielectric constant detection module, the parallel plate electrode spacing is 15mm, and the impedance analyzer frequency is 500kHz.

[0055] Set temperature T = 150℃ (allowable deviation ± 1.5℃), pressure P = 4MPa (allowable deviation ± 0.08MPa), raw material concentration N = 35% (allowable deviation ± 0.8%);

[0056] The stirring speed is initially set to 800rpm and adjusted to 950rpm according to the dielectric constant feedback;

[0057] The supercritical CO2 injection amount is 4kg / h, and the mixing uniformity UI is ≥99%.

[0058] The experimental results are as follows: the actual temperature fluctuation is ±1.5℃, the mixing time is 55 minutes, the raw material loss rate is 2.5%, the product qualified rate is 99.5%, the raw rubber viscosity is reduced from the initial 2500mPa·s to 780mPa·s, and the dispersion uniformity is observed by microscope without particle agglomeration.

[0059] Verification data:

[0060] Parameters Conventional system Example 2 Example 3 Lifting amplitude Temperature fluctuation ±8℃ ±1.8℃ ±1.5℃ 77.5％↓ / 81.3％↓ Mixing time 120 min 58 min 55 min 51.7％↓ / 54.2％↓ Raw material loss rate 15％ 2.8％ 2.5％ 81.3％↓ / 83.3％↓ Product qualification rate 92％ 99％ 99.5％ 7.6％↑ / 8.2％↑

[0061] Both Example Two and Example Three meet the technical indicators of temperature fluctuation ≤±2℃ and raw material loss rate ≤3%; the control strategy realizes parameter decoupling in both materials in Example Two and Example Three, verifying the applicability of the algorithm.

[0062] The pressurized mixing system in the closed cavity realizes the whole-process closed processing of the powder and liquid raw materials through the closed mixing cavity design, combines the supercritical fluid injection technology, reduces the raw material loss rate to below 3%, and completely eliminates the emission of volatile substances, significantly reduces the environmental pollution risk, and the closed environment avoids oxygen contact, which is suitable for stable mixing of easily oxidized materials. Moreover, the dielectric constant real-time feedback mixing uniformity technology is adopted, the material uniformity index is improved to above 98% through the linkage of parallel plate electrodes and impedance analyzers, the traditional subjective experience judgment is replaced, the supercritical fluid viscosity reduction technology is combined, the high-viscosity material dispersion problem is efficiently solved, and the mixing time is shortened. Meanwhile, the pressure-temperature decoupling control algorithm and the multivariable PID model are adopted, the dynamic and accurate control of temperature, pressure and concentration is realized, the product qualified rate is improved to above 99%, the closed-loop control system integrates the above technologies, forms an automatic production architecture, reduces the manual operation intensity, and is suitable for continuous production of various membrane products.

[0063] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A pressurized mixing system within a sealed cavity, comprising a sealed mixing device, a fluid injection system, a multi-parameter detection system, and a control system, characterized in that: The closed mixing device is used to accommodate raw materials in various forms and to achieve pressurized mixing; the fluid injection system is connected to the closed mixing device and is used to inject working fluid to adjust the rheological properties of the material. The multi-parameter detection system is used to acquire the process parameters inside the closed mixing device in real time; the control system dynamically regulates the mixing process based on the detection parameters through decoupling control algorithms and multivariable coupling models; the closed mixing device, fluid injection system, multi-parameter detection system and control system work together through signal and material transmission paths to form a closed-loop control architecture.

2. The pressurized mixing system in a sealed cavity according to claim 1, characterized in that: The closed mixing device includes a pressure-resistant chamber, a stirring assembly, a feed inlet, a discharge outlet, and an exhaust valve. The pressure-resistant chamber adopts a double-layer jacket structure, with an inner layer of 316L stainless steel and an outer insulation layer. The stirring assembly is located inside the chamber and is driven by a variable frequency motor with a stirring speed range of 0-1200 rpm. The feed inlet and discharge outlet are used for feeding and discharging raw materials, and the exhaust valve is connected to a vacuum pump for evacuating air.

3. The pressurized mixing system in a sealed cavity according to claim 1, characterized in that: The fluid injection system includes a fluid storage tank, a booster pump, and a flow meter. The fluid storage tank is used to hold supercritical fluid; the booster pump is used to adjust the fluid injection rate according to the control system instructions; and the flow meter has an accuracy of ±1%.

4. The pressurized mixing system in a sealed cavity according to claim 3, characterized in that: The supercritical fluid is CO2, the injection rate is 0-10 kg / h, the stirring speed is set to 400-800 rpm, the temperature is controlled within the range of 120-180℃, and the pressure is controlled within the range of 2-4 MPa.

5. The pressurized mixing system in a sealed cavity according to claim 1, characterized in that: The multi-parameter detection system includes a pressure detection unit, a temperature detection unit, a concentration detection unit, and a dielectric constant detection unit. The pressure detection unit uses a piezoresistive sensor with a range of 0-5 MPa; the temperature detection unit uses a platinum resistance sensor with an accuracy of ±0.5℃; the concentration detection unit uses laser scattering method with a response time ≤1s; and the dielectric constant detection unit includes parallel plate electrodes and an impedance analyzer, with the parallel plate electrode spacing being 10-20 mm.

6. The pressurized mixing system in a closed cavity according to claim 5, characterized in that: The dielectric constant detection unit converts the measured dielectric constant into a uniformity index UI. A UI ≥ 95% indicates uniform mixing. The formula for calculating UI is: In the formula, εreal is the measured dielectric constant, and εideal is the theoretical uniform dielectric constant.

7. The pressurized mixing system in a closed cavity according to claim 1, characterized in that: The control system includes an industrial computer and an actuator. The industrial computer has a built-in decoupling control algorithm and a multivariable PID control model. The actuator includes a variable frequency motor, a heating element, and a booster pump, which are used to regulate the mixing process.

8. The pressurized mixing system in a closed cavity according to claim 7, characterized in that: The decoupling control algorithm achieves parameter decoupling through the following: Q = α·ΔP + β·ΔT + γ·ΔN In the formula, Q is the comprehensive control quantity, ΔP is the pressure deviation, ΔT is the temperature deviation, ΔN is the concentration deviation, and α, β, and γ are weighting coefficients, satisfying α+β+γ=1.

9. A pressurized mixing system in a closed cavity according to claim 8, characterized in that: The multivariable PID control model uses the following dynamically coupled parameters: In the formula, e(t) is the error vector between the set value and the measured value, which includes the parameters of temperature (T), pressure (P), and concentration (N), and K p K i K d Let K be the proportional, integral, and differential coefficients, satisfying K p :K i :K d =1.2:0.5:0.

3.

10. A pressurized mixing system within a sealed cavity according to claim 9, characterized in that: The weighting coefficients α = 0.6, β = 0.3, and γ = 0.1 were optimized through experimental calibration; the allowable deviation range of the error vector e(t) is: T set value ±2℃, P set value ±0.1MPa, and N set value ±1%.

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