Sterilization tank and sterilization method
Patent Information
- Application Number
- CN202511177849.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-11-14
Smart Images
Figure CN120939256A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biotechnology, and more particularly to a sterilization tank and sterilization method. Background Technology
[0002] Bio-based fiber pulps (such as bamboo / bagasse / straw, etc.) are widely used in the molding process of biodegradable tableware, environmentally friendly packaging, and disposable hygiene products. These products are intended for food contact or hygiene applications, requiring the physical sterilization of high-solids (typically medium to high viscosity) pulps before molding to simultaneously ensure microbial safety and maintain material performance (limiting fiber polymerization loss and avoiding chemical residues). Because the process tends to increase solids content to reduce drying energy consumption and improve molding efficiency, the pulp rheology exhibits high viscosity, easy agglomeration, and adhesion characteristics, leading to limited heat and mass transfer. This places higher demands on sterilization equipment and methods, requiring them to be "short-duration, highly efficient, and temperature-uniform."
[0003] Existing technologies mostly employ saturated steam jackets / direct injection and conventionally stirred sterilization tanks for heating and heat preservation, with some models supplemented by simple rotary or paddle stirring. Control is primarily based on internal temperature and pressure, supplemented by a few point temperature measurements. Under high-solids slurry conditions, increased viscosity leads to a significant decrease in the Reynolds number, causing flow to tend towards laminar flow. Internal convection is suppressed, and heat transfer is dominated by conduction between the wall and the slurry, easily leading to agglomeration and dead zones. When a temperature difference exists within the slurry, the instantaneous sterilization rate in the lowest temperature zone is significantly lower than that at the wall, resulting in a lag in the cumulative sterilization value within the same timeframe. To compensate for this lag, traditional solutions can only extend the holding time or increase the platform temperature, but both lead to fiber thermal degradation and a decrease in polymerization degree; if not extended, the sterilization value in the lowest temperature zone is difficult to meet the standard, resulting in insufficient sterilization.
[0004] Therefore, it is necessary to improve the existing sterilization technology to solve the problems of uneven heating and insufficient sterilization during the sterilization process. Summary of the Invention
[0005] The purpose of this invention is to provide a sterilization tank and sterilization method to solve the above-mentioned technical problems.
[0006] To achieve this objective, the present invention adopts the following technical solution: A sterilization method comprising the following steps: S1, the bio-based fiber pulp is degassed through a vacuum system, and the target sterilization value F0 and the fiber polymerization degree loss threshold are preset. S2, start the heating and homogenization mode, control the stirring roller to run at a preset small expansion amplitude and speed, so that the slurry is heated evenly at a heating slope of 2~4℃ / min, and monitor the temperature at multiple points in real time. If the temperature difference between any two points is >3℃, increase the microwave duty cycle and increase the expansion amplitude of the stirring roller with the first amplitude. S3, when the monitored lowest temperature point reaches 132~138℃, the high-temperature short-time sterilization stage begins, maintained for 25~45s, and the sterilization F-value is calculated in real time through integration. If the F-value does not reach F0 or the motor feedback torque suddenly increases by >15%, then: Increase the expansion amplitude of the stirring roller with the second amplitude, trigger the steam pulse mode, and increase the microwave power by 5% to 10%.
[0007] Optionally, the following steps may be included after step S3: S4. After the sterilization stage is completed, the high pressure stage is entered. The chamber pressure is maintained at 0.2~0.3 MPa and the stirring roller is fully deployed and circulated for 15~30s. At the same time, ATP rapid detection is performed through the interlock sampling port. If the detection fails, the high pressure maintenance time is automatically extended by 10~20s. S5, shut off the heat source and turn on the steam jacket cooling and inert micro-nano bubble injection system, control the slurry to drop to 85~90℃ with a temperature difference of ≤5℃ before discharge, trigger the automatic CIP / SIP cleaning program and generate an electronic batch record containing F-value curves, temperature and torque data.
[0008] Optionally, the setting rule for the target sterilization value F0 is: based on the safety standards for killing microorganisms and combined with the safety margin required by the target product, it is preferable to take F0≥8~12; The rule for setting the fiber polymerization degree loss threshold is as follows: based on the material property retention requirements of the slurry, the loss rate is limited to ≤5% by comparing the polymerization degree of the untreated slurry.
[0009] Optionally, the process of degassing the bio-based fiber slurry using a vacuum system is as follows: S11, the pretreated bio-based fiber slurry is introduced into the sterilization tank cavity through the delivery pipeline, and the vacuum is started to reduce the cavity pressure to -0.06 to -0.08 MPa. At the same time, the slurry is driven to form a low-speed circulation by slow stirring. S12, the temperature control system is activated simultaneously during the vacuuming process to maintain the cavity temperature in a constant range of 40-50°C, and the set vacuum-slow release cycle mode is used to further reduce residual microbubbles. S13. After the differential pressure ΔP measured by the differential pressure sensor at both ends of the cavity stabilizes, the bubble volume fraction ε is calculated, and online optical turbidity detection and slurry viscosity detection are triggered as consistency checks to determine whether the slurry has reached a fully degassed state. If so, the degassed process is stopped and the slurry is output; otherwise, the operation mode of extended vacuum and high shear low amplitude stirring is triggered.
[0010] Optionally, the process of calculating the bubble volume fraction ε is as follows: According to the apparent density of the slurry ρa=ΔP / (g·h), where g is the gravitational acceleration constant and h is the vertical height difference between the two ends of the cavity; Based on the known solid volume fraction φ and phase densities ρs and ρl, the bubble volume fraction is estimated using ε = 1 - ρa / [φ·ρs + (1 - φ)·ρl].
[0011] Optionally, the process of determining whether the slurry has reached a fully degassed state is as follows: Turbidity values are detected by online optical turbidity detection, and viscosity values are converted from motor feedback torque data. Combined with the calculated apparent density ρa, a trend curve of turbidity value - viscosity value - apparent density ρa is plotted with time t as the horizontal axis. If, under constant temperature conditions, the trend curves of turbidity value, viscosity value, and apparent density ρa tend to match, then it is determined that the state of sufficient degassing has been reached. If, under constant temperature conditions, the trends of the turbidity value, viscosity value, and apparent density ρa are different, or if the calculated bubble volume fraction ε is higher than the set threshold, then it is determined to be an insufficiently degassed state.
[0012] Optionally, the sterilization tank further includes: Microwave coupler is used for volumetric heating of the slurry interior; Steam jacket is used to conduct heat evenly to the walls of the sterilization tank; An ultrasonic transducer ring array is used to promote the breakup and homogeneous dispersion of bubbles inside the slurry through cavitation and acoustic flow.
[0013] Optionally, step S5 specifically includes: S51, after completing the high-pressure stage, first shut down the microwave coupler and ultrasonic transducer ring array, and gradually reduce the heat flow of the steam jacket until the heat source is completely shut off. S52, after the heat source is turned off, starts the steam jacket cooling cycle, controls the cooling medium to gradually reduce the slurry temperature at a cooling rate of ≤1.5℃ / min, and calculates the temperature difference between various points of the slurry in real time through multi-point temperature sensors. When the temperature difference is greater than 5℃, the stirring roller is automatically triggered to expand slightly to assist in temperature uniformity. S53, during the cooling cycle, the inert micro-nano bubble injection system is activated to dissolve nitrogen or carbon dioxide into the slurry at low pressure. The high specific surface area of the micro-nano bubbles is used to achieve rapid heat exchange of the slurry, while the displacement effect inhibits the damage of residual oxygen to the degree of fiber polymerization. S54, when the overall temperature of the slurry drops to 85~90℃ and the temperature difference at any point is ≤5℃, the automatic discharge mechanism is activated to discharge the slurry. During the discharge process, the CIP / SIP cleaning pipeline is pre-flushed. After completing the discharge and cleaning process, S55 automatically generates an electronic batch record. The record includes the F-value curve, temperature distribution data, and stirring torque curve of the entire sterilization process, and is uploaded to the factory database through the traceability information module.
[0014] The present invention also provides a sterilization tank for implementing the sterilization method described above, the sterilization tank comprising: The tank and the vacuum system connected to it are used for degassing bio-based fiber pulp. A steam jacket, installed on the outer wall of the tank, is used for uniform heating and cooling of the tank. Microwave couplers and ultrasonic transducer arrays are installed inside the tank. The stirring roller, located at the bottom of the tank, has an adjustable expansion range to achieve slurry mixing and temperature uniformity; Multiple temperature sensors and torque monitoring modules distributed inside the tank are used for process status monitoring; An inert micro / nano bubble injection system connected to the tank is used for cooling and inhibiting oxidative degradation of the slurry; An automatic feeding mechanism and a CIP / SIP cleaning system are used for material discharge and online cleaning.
[0015] Compared with existing technologies, this invention has the following advantages: First, the bio-based fiber slurry is degassed using a vacuum system, and a target sterilization value F0 and a fiber polymerization degree loss threshold are preset; a heating homogenization mode is activated, and the slurry is heated uniformly at a heating slope of 2-4℃ / min while the stirring roller operates at a small expansion amplitude and a preset speed, and the temperature at multiple points is monitored in real time. When the temperature difference between any two points is detected to be greater than 3℃, the microwave duty cycle is automatically increased and the expansion amplitude of the stirring roller is adjusted with the first amplitude to ensure heating uniformity; when the lowest temperature point rises to 132-138℃, a high-temperature short-time sterilization stage is entered and maintained for 25-45 seconds. Simultaneously, the sterilization F-value is calculated in real time. If the F-value does not reach the set target F0 during this process, or if the motor feedback torque suddenly increases by more than 15%, the agitator roller expansion amplitude is further increased by a second amplitude, triggering the steam pulse mode, and the microwave power is increased by 5% to 10% to ensure thorough sterilization and homogeneous slurry. This method can quickly achieve high-temperature short-time sterilization while ensuring uniform temperature distribution. During the sterilization process, the process parameters are corrected according to the real-time temperature difference and torque changes, thereby effectively avoiding cold spots and agglomeration in the slurry, ensuring that the sterilization F-value is stably up to standard, and reducing damage to the degree of fiber polymerization. This achieves rapid, uniform, and gentle high-efficiency sterilization of bio-based fiber slurry. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.
[0018] Figure 1 This is one of the flowcharts illustrating the sterilization method in this embodiment. Figure 2 This is the second schematic diagram of the sterilization method in this embodiment one; Figure 3 This is one of the front view structural schematic diagrams of the sterilization tank in this embodiment two; Figure 4 This is a cross-sectional schematic diagram of the sterilization tank in this embodiment 2. Detailed Implementation
[0019] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0020] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.
[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0022] Example 1: Combination Figure 1 and Figure 2 As shown, this embodiment of the invention provides a sterilization method, including the following steps: S1, the bio-based fiber slurry is degassed through a vacuum system to achieve a vacuum level of -0.06 to -0.08 MPa in the cavity, and the target sterilization value F0 and the fiber polymerization degree loss threshold are preset.
[0023] This treatment effectively removes dissolved gases and entrained air bubbles from the slurry, reducing the risk of localized overheating and uneven temperature distribution caused by bubble aggregation during subsequent heating. Simultaneously, pre-setting the target sterilization value F0 and the fiber polymerization degree loss threshold provides benchmark parameters for process control throughout the sterilization process.
[0024] S2, activate the heating and homogenization mode, control the stirring roller to run at a preset small expansion amplitude and speed, so that the slurry is heated evenly at a heating slope of 2~4℃ / min, and monitor the temperature at multiple points in real time. If the temperature difference between any two points is >3℃, increase the microwave duty cycle and increase the expansion amplitude of the stirring roller with the first amplitude.
[0025] It should be noted that during this process, multiple temperature monitoring points are set up in real time to detect local temperature differences. If the temperature difference between any two points exceeds 3°C, the microwave duty cycle is automatically adjusted and the expansion amplitude of the stirring roller is increased to further improve the fluidity and heat transfer uniformity of the slurry, ensuring that the slurry is heated evenly during the heating process and reducing the risk of premature deterioration of fiber polymerization.
[0026] S3, when the monitored lowest temperature point reaches 132~138℃, enter the high temperature short-time sterilization stage, maintain for 25~45s and calculate the sterilization F value in real time. If the F value does not reach F0 or the motor feedback torque suddenly increases by more than 15%, then: increase the expansion amplitude of the stirring roller with the second amplitude, trigger the steam pulse mode, and increase the microwave power by 5%~10%.
[0027] It should be noted that the system calculates the sterilization F-value in real time to ensure that the preset target sterilization intensity is achieved. When the F-value is detected to be below the set target F0, or when there is a sudden increase of more than 15% in the motor feedback torque, the system automatically responds by increasing the spread of the stirring rollers, triggering the steam pulse mode, and increasing the microwave power to improve the local heat transfer and flow state of the slurry. This step can achieve a reliable sterilization effect in a short time, while dynamically adjusting the process to ensure that the sterilization requirements are met while avoiding problems such as local agglomeration of the slurry or excessive fiber degradation.
[0028] S4. After completing the sterilization stage, it enters the high-pressure stage, maintaining the chamber pressure at 0.2~0.3MPa and performing a full-expansion cycle of the stirring roller for 15~30s. Simultaneously, ATP rapid testing is performed through the interlocked sampling port. If the test fails, the high-pressure maintenance time is automatically extended by 10~20s.
[0029] Rapid ATP testing is performed through interlocked sampling ports to instantly verify whether the sterilization effect meets the requirements. When the test fails, the system can automatically extend the high-pressure maintenance time by 10-20 seconds, thereby ensuring the stability and safety of the sterilization process. It provides an online quality monitoring and process compensation mechanism, which helps to improve the reliability of the sterilization process.
[0030] S5, shut off the heat source and turn on the steam jacket cooling and inert micro-nano bubble injection system, control the slurry to drop to 85~90℃ with a temperature difference of ≤5℃ before discharge, trigger the automatic CIP / SIP cleaning program and generate an electronic batch record containing F-value curves, temperature and torque data.
[0031] After completing the high-pressure stage, the system shuts off the heat source and activates the steam jacket's cooling function. Simultaneously, an inert micro-nano bubble injection system is introduced to accelerate the uniform cooling of the slurry and suppress potential oxidation reactions at high temperatures. Through process control, the slurry temperature is maintained at a uniform difference of ≤5℃ during cooling until it reaches 85~90℃ before discharge. An automatic CIP / SIP cleaning program is then triggered to ensure the equipment remains sterile and clean between batches. An electronic batch record is automatically generated, including F-value curves, temperature data, and torque records. This not only achieves rapid cooling and quality assurance before discharge but also provides traceable data support for the production process.
[0032] The working principle of this invention is as follows: First, the bio-based fiber slurry is degassed using a vacuum system, and a target sterilization value F0 and a fiber polymerization degree loss threshold are preset. Then, a heating homogenization mode is activated, and the slurry is heated uniformly at a rate of 2–4 °C / min while the stirring roller operates at a small expansion amplitude and a preset speed. Multiple temperature points are monitored in real time. When the temperature difference between any two points is detected to be greater than 3 °C, the microwave duty cycle is automatically increased, and the expansion amplitude of the stirring roller is adjusted to the first amplitude to ensure heating uniformity. When the lowest temperature point reaches 132–138 °C, a high-temperature short-time sterilization stage is initiated and maintained for 25–45 seconds, while real-time accumulation... The sterilization F-value is calculated. If the F-value does not reach the set target F0 during the process, or if the motor feedback torque suddenly increases by more than 15%, the agitator roller expansion amplitude is further increased by a second amplitude, triggering the steam pulse mode, and the microwave power is increased by 5% to 10% to ensure thorough sterilization and homogeneous slurry. This method can quickly achieve high-temperature short-time sterilization while ensuring uniform temperature distribution. During the sterilization process, the process parameters are adjusted according to the real-time temperature difference and torque changes, thereby effectively avoiding cold spots and agglomeration in the slurry, ensuring that the sterilization F-value is stably up to standard, and reducing damage to the degree of fiber polymerization. This achieves rapid, uniform, and gentle high-efficiency sterilization of bio-based fiber slurry.
[0033] In this embodiment, the setting rule for the target sterilization value F0 is: based on the safety standards for killing microorganisms and combined with the safety margin required by the target product, it is preferable to take F0≥8~12; this can ensure that while achieving sufficient sterilization effect, the problem of increased energy consumption or deterioration of material performance caused by excessive heat treatment is avoided.
[0034] The rule for setting the fiber polymerization degree loss threshold is as follows: based on the material property retention requirements of the slurry, the loss rate is limited to ≤5% by comparing the polymerization degree of untreated slurry. This ensures that the mechanical properties, forming properties, and application stability of the bio-based fiber slurry are not significantly affected while achieving effective sterilization.
[0035] In this embodiment, the process of degassing the bio-based fiber slurry using a vacuum system is specifically described as follows: S11, the pretreated bio-based fiber slurry is introduced into the sterilization tank cavity through the delivery pipeline, and the vacuum is activated to reduce the cavity pressure to -0.06 to -0.08 MPa. At the same time, slow stirring is used to drive the slurry to form a low-speed circulation to promote the release of free gas inside the slurry and interface bubbles.
[0036] It should be noted that the pretreated bio-based fiber slurry is introduced into the sterilization tank cavity through a delivery pipeline, and a vacuum is immediately initiated to reduce the cavity pressure to a negative pressure range of -0.06 to -0.08 MPa. This negative pressure environment effectively reduces the stability of dissolved gases within the slurry, making it easier for gases to precipitate from the liquid phase. Simultaneously, slow stirring creates a low-speed circulation, helping the slurry maintain a dynamic flow state, thus facilitating the desorption and release of internal free gases and interfacial bubbles adhering to the fiber surface, preventing localized bubble retention.
[0037] S12, during the vacuuming process, simultaneously activates the temperature control system to maintain the chamber temperature in a constant range of 40-50°C. By reducing the viscosity of the slurry, it accelerates the diffusion and escape of dissolved gases, and further reduces residual microbubbles by utilizing the set vacuum-slow release circulation mode.
[0038] The vacuuming process is combined with temperature control. By maintaining the chamber within a constant temperature range of 40–50°C, the viscosity of the slurry is moderately reduced, thereby improving the diffusion rate and escape efficiency of dissolved gases. Simultaneously, a vacuum-slow-release circulation mode is employed. This involves intermittently releasing some pressure during continuous vacuuming, followed by re-vacuuming. This periodic pressure change disturbs the slurry's microenvironment, gradually releasing residual microbubbles that are difficult to escape. This process ensures more thorough degassing and reduces the risk of microbubble accumulation in the slurry.
[0039] S13. After the differential pressure ΔP measured by the differential pressure sensor at both ends of the cavity stabilizes, the bubble volume fraction ε is calculated, and online optical turbidity detection and slurry viscosity detection are triggered as consistency checks to determine whether the slurry has reached a fully degassed state. If so, the degassed process is stopped and the slurry is output; otherwise, the operation mode of extended vacuum and high shear low amplitude stirring is triggered.
[0040] The pressure difference between the two ends of the cavity is detected by a differential pressure sensor inside the cavity. When the differential pressure ΔP tends to stabilize, the volume fraction of air bubbles ε inside the slurry can be calculated, and online optical turbidity detection and slurry viscosity detection are further triggered to verify the consistency of the degassing state. This multi-dimensional detection method can comprehensively evaluate the slurry degassing effect from three perspectives: macroscopic (ΔP stability), microscopic (turbidity change), and rheological properties (viscosity change). When the detection result shows that the slurry has reached a fully degassed state, the system automatically stops the degassing process and outputs the slurry; if the detection shows that there are still air bubbles that have not been completely removed, the extended vacuum process is triggered, combined with high shear and low amplitude stirring, to further break up and remove residual air bubbles, ensuring the homogeneity of the slurry and the stability of the subsequent sterilization and heating process.
[0041] In this embodiment, the process of calculating the bubble volume fraction ε is further explained as follows: According to the apparent density of the slurry ρa=ΔP / (g·h), where g is the gravitational acceleration constant and h is the vertical height difference between the two ends of the cavity; Based on the known solid volume fraction φ and phase densities ρs and ρl, the bubble volume fraction is estimated using ε = 1 - ρa / [φ·ρs + (1 - φ)·ρl].
[0042] It should be noted that the calculation of the bubble volume fraction ε is derived based on the change in the apparent density of the slurry. Specifically, the apparent density ρa of the slurry in the cavity can be converted from the pressure difference ΔP at both ends measured by the differential pressure sensor to ρa = ΔP / (g·h).
[0043] This method can indirectly reflect the influence of air bubbles in the slurry on the overall density through the static pressure difference of the liquid column. Given the solid volume fraction φ, fiber phase density ρs, and liquid phase density ρl of the slurry, the theoretical density can be calculated using a mixture density model and estimated using the formula ε = 1 - ρa / [φ·ρs + (1 - φ)·ρl]. This calculation method can effectively quantify the volume fraction of residual air bubbles in the slurry, thus providing an objective indicator for judging the degassing effect.
[0044] In this embodiment, the process of determining whether the slurry has reached a fully degassed state is further explained as follows: Turbidity values are detected by online optical turbidity detection, and viscosity values are converted from motor feedback torque data. Combined with the calculated apparent density ρa, a trend curve of turbidity value - viscosity value - apparent density ρa is plotted with time t as the horizontal axis. If, under constant temperature conditions, the trend curves of turbidity value, viscosity value, and apparent density ρa tend to match, then it is determined that the state of sufficient degassing has been reached. If, under constant temperature conditions, the trends of the turbidity value, viscosity value, and apparent density ρa are different, or if the calculated bubble volume fraction ε is higher than the set threshold, then it is determined to be an insufficiently degassed state.
[0045] It should be noted that the process of determining whether the slurry has reached a fully degassed state combines multi-dimensional detection results. Specifically, the system uses an online optical sensor to detect turbidity values in real time, converts motor feedback torque data into slurry viscosity values, and combines this with the calculated apparent density ρa to plot the changes of these three values over time as a trend curve.
[0046] When the slurry is under constant temperature conditions, if the trends of the three curves of turbidity, viscosity and apparent density tend to be consistent and the fluctuations tend to be stable, it indicates that the air bubbles inside the slurry have been basically removed and the slurry has reached a fully degassed state. Conversely, if there is obvious separation between the three curves, or if the air bubble volume fraction ε calculated by the formula is still higher than the preset threshold (such as 1%), it is determined to be an insufficiently degassed state.
[0047] This method improves the reliability of judgment by ensuring the consistency of trends of multiple parameters, thus avoiding misjudgments that may be caused by monitoring a single parameter.
[0048] In this embodiment, the sterilization tank further includes: Microwave couplers are used for volumetric heating of the slurry interior, shortening the heat transfer path and improving the heating rate and uniformity.
[0049] The steam jacket is used to conduct heat evenly to the walls of the sterilization tank, preventing overheating or cold spots in the slurry near the tank wall, thus complementing microwave heating.
[0050] An ultrasonic transducer ring array is used to promote the breakup and homogeneous dispersion of bubbles inside the slurry through cavitation and acoustic flow, further promoting the homogeneity of flow and the consistency of heat conduction within the slurry.
[0051] In this embodiment, step S5 specifically includes: S51, after completing the high-pressure stage, first shut down the microwave coupler and ultrasonic transducer array, and gradually reduce the heat flow of the steam jacket until the heat source is completely shut off, so as to ensure that the slurry temperature rise process is terminated and to avoid overheating.
[0052] By sequentially shutting off the microwave coupler and ultrasonic transducer array, and gradually reducing the heat flow of the steam jacket until the heat source is completely shut off, the slurry can be prevented from continuing to heat up, thus preventing additional loss of fiber polymerization due to overheating. Simultaneously, this operation helps establish stable initial cooling conditions, making the subsequent cooling process more controllable.
[0053] S52, after the heat source is turned off, starts the steam jacket cooling cycle, controls the cooling medium to gradually reduce the slurry temperature at a cooling rate of ≤1.5℃ / min, and calculates the temperature difference between various points of the slurry in real time through multi-point temperature sensors. When the temperature difference is greater than 5℃, the stirring roller is automatically triggered to expand slightly to assist in temperature uniformity.
[0054] It should be noted that controlled cooling of the slurry is achieved by activating the cooling cycle of the steam jacket. By limiting the cooling rate of the cooling medium to ≤1.5℃ / min, thermal stress caused by a sudden drop in temperature can be avoided, maintaining the stability of the slurry's performance. Simultaneously, multi-point temperature sensors monitor and calculate the temperature difference between different points in real time. When the temperature difference exceeds 5℃, the system automatically triggers a slight expansion of the stirring rollers to enhance the convective mixing within the slurry, thereby achieving a more uniform temperature distribution and improving the overall consistency of the cooling process.
[0055] S53, during the cooling cycle, activates the inert micro-nano bubble injection system to dissolve nitrogen or carbon dioxide into the slurry at low pressure. The high specific surface area of the micro-nano bubbles enables rapid heat exchange in the slurry, while the displacement effect inhibits the damage of residual oxygen to the degree of fiber polymerization.
[0056] It should be noted that an inert micro / nano bubble injection system was introduced, primarily to further enhance heat exchange efficiency and improve the chemical stability of the slurry during the cooling process. By dissolving nitrogen or carbon dioxide into the slurry under low pressure, the high specific surface area of the micro / nano bubbles promotes rapid heat transfer, accelerating the overall cooling process of the slurry. Simultaneously, the micro / nano bubbles can displace residual oxygen in the slurry during dissolution and diffusion, thereby reducing the adverse effects of oxidation on fiber polymerization and helping to maintain the slurry's performance.
[0057] S54 When the overall temperature of the slurry drops to 85~90℃ and the temperature difference at any point is ≤5℃, the automatic discharge mechanism is activated to discharge the slurry. During the discharge process, the CIP / SIP cleaning pipeline is pre-flushed to reduce the risk of residual contamination and improve cleaning efficiency.
[0058] Step S54 ensures the slurry is discharged under suitable conditions. Specifically, when the overall slurry temperature drops to 85-90°C and the temperature difference between any points does not exceed 5°C, the system automatically activates the discharge mechanism to discharge the slurry in an orderly manner. Simultaneously, the discharge process is linked to the pre-rinsing action of the CIP / SIP cleaning pipeline, enabling cleaning preparation to proceed while discharging, thereby reducing the risk of residual contamination and improving efficiency for subsequent thorough cleaning.
[0059] After completing the discharge and cleaning startup, the S55 automatically generates an electronic batch record. This record includes the F-value curve, temperature distribution data, and stirring torque curve for the entire sterilization process. This record is then uploaded to the factory database via a traceability module, enabling online verification and retention of batch quality. Uploading this record to the factory database through the traceability module not only serves as online verification of batch quality but also provides data support for process optimization and long-term quality management.
[0060] Example 2: Combination Figure 3 and Figure 4 As shown, the present invention also provides a sterilization tank for implementing the sterilization method as described in Example 1. The sterilization tank includes: The tank 10 and the vacuum system 20 connected thereto are used for degassing the bio-based fiber pulp. A steam jacket 70 is installed on the outer wall of the tank 10 and is used to uniformly heat and cool the tank 10. The microwave coupler and the ultrasonic transducer ring array are respectively installed inside the tank 10; A stirring roller 60 is located at the bottom of the tank 10 and has an adjustable expansion range to achieve slurry mixing and temperature uniformity. Multi-point temperature sensors 30 and torque monitoring modules distributed inside the tank 10 are used for process status monitoring; An inert micro-nano bubble injection system 40, connected to the tank 10, is used for cooling and inhibiting the oxidative degradation of the slurry; An automatic material discharge mechanism 50 and a CIP / SIP cleaning system 60 are used for material discharge and online cleaning.
[0061] The working principle of this invention is as follows: Pretreated bio-based fiber slurry is introduced into chamber 10 of the tank via a vacuum system and degassed to remove free gas and interfacial bubbles. Subsequently, a steam jacket provides uniform heating, and with the synergistic effect of a microwave coupler and an ultrasonic transducer array, the slurry heats up rapidly and uniformly. Simultaneously, an adjustable expansion roller drives the slurry to circulate fully, achieving mixing and temperature homogenization. Throughout the process, multiple temperature sensors and a torque monitoring module collect real-time operating data, providing a basis for process control and status assessment. After high-temperature sterilization, the steam jacket switches to cooling mode and activates an inert micro / nano bubble injection system to accelerate cooling and inhibit oxidative degradation of the slurry. When the slurry reaches the target discharge temperature and stabilizes, it is discharged via an automatic discharge mechanism. Simultaneously, a CIP / SIP cleaning system is triggered to complete online cleaning and regeneration preparation of the chamber, thus achieving a continuous, safe, and traceable sterilization and discharge process.
[0062] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A sterilization method, characterized in that, Includes the following steps: S1, the bio-based fiber pulp is degassed through a vacuum system, and the target sterilization value F0 and the fiber polymerization degree loss threshold are preset. S2, start the heating and homogenization mode, control the stirring roller to run at a preset small expansion amplitude and speed, so that the slurry is heated evenly at a heating slope of 2~4℃ / min, and monitor the temperature at multiple points in real time. If the temperature difference between any two points is >3℃, increase the microwave duty cycle and increase the expansion amplitude of the stirring roller with the first amplitude. S3, when the monitored lowest temperature point reaches 132~138℃, the high-temperature short-time sterilization stage begins, maintained for 25~45s, and the sterilization F-value is calculated in real time through integration. If the F-value does not reach F0 or the motor feedback torque suddenly increases by >15%, then: Increase the expansion amplitude of the stirring roller with the second amplitude, trigger the steam pulse mode, and increase the microwave power by 5% to 10%.
2. The sterilization method according to claim 1, characterized in that, Following step S3, the following steps are also included: S4. After the sterilization stage is completed, the high pressure stage is entered. The chamber pressure is maintained at 0.2~0.3 MPa and the stirring roller is fully deployed and circulated for 15~30s. At the same time, ATP rapid detection is performed through the interlock sampling port. If the detection fails, the high pressure maintenance time is automatically extended by 10~20s. S5, shut off the heat source and turn on the steam jacket cooling and inert micro-nano bubble injection system, control the slurry to drop to 85~90℃ with a temperature difference of ≤5℃ before discharge, trigger the automatic CIP / SIP cleaning program and generate an electronic batch record containing F-value curves, temperature and torque data.
3. The sterilization method according to claim 1, characterized in that, The setting rule for the target sterilization value F0 is as follows: based on the safety standards for killing microorganisms and combined with the safety margin required by the target product, F0 ≥ 8~12 is preferred. The rule for setting the fiber polymerization degree loss threshold is as follows: based on the material property retention requirements of the slurry, the loss rate is limited to ≤5% by comparing the polymerization degree of the untreated slurry.
4. The sterilization method according to claim 1, characterized in that, The process of degassing the bio-based fiber pulp using a vacuum system is as follows: S11, the pretreated bio-based fiber slurry is introduced into the sterilization tank cavity through the delivery pipeline, and the vacuum is started to reduce the cavity pressure to -0.06 to -0.08 MPa. At the same time, the slurry is driven to form a low-speed circulation by slow stirring. S12, the temperature control system is activated simultaneously during the vacuuming process to maintain the cavity temperature in a constant range of 40-50°C, and the set vacuum-slow release cycle mode is used to further reduce residual microbubbles. S13. After the differential pressure ΔP measured by the differential pressure sensor at both ends of the cavity stabilizes, the bubble volume fraction ε is calculated, and online optical turbidity detection and slurry viscosity detection are triggered as consistency checks to determine whether the slurry has reached a fully degassed state. If so, the degassed process is stopped and the slurry is output; otherwise, the operation mode of extended vacuum and high shear low amplitude stirring is triggered.
5. The sterilization method according to claim 4, characterized in that, The process for calculating the bubble volume fraction ε is as follows: According to the apparent density of the slurry ρa=ΔP / (g·h), where g is the gravitational acceleration constant and h is the vertical height difference between the two ends of the cavity; Based on the known solid volume fraction φ and phase densities ρs and ρl, the bubble volume fraction is estimated using ε = 1 - ρa / [φ·ρs + (1 - φ)·ρl].
6. The sterilization method according to claim 5, characterized in that, The process for determining whether the slurry has reached a fully degassed state is as follows: Turbidity values are detected by online optical turbidity detection, and viscosity values are converted from motor feedback torque data. Combined with the calculated apparent density ρa, a trend curve of turbidity value - viscosity value - apparent density ρa is plotted with time t as the horizontal axis. If, under constant temperature conditions, the trend curves of turbidity value, viscosity value, and apparent density ρa tend to match, then it is determined that the state of sufficient degassing has been reached. If, under constant temperature conditions, the trends of the turbidity value, viscosity value, and apparent density ρa are different, or if the calculated bubble volume fraction ε is higher than the set threshold, then it is determined to be an insufficiently degassed state.
7. The sterilization method according to claim 1, characterized in that, The sterilization tank also includes: Microwave coupler is used for volumetric heating of the slurry interior; Steam jacket is used to conduct heat evenly to the walls of the sterilization tank; An ultrasonic transducer ring array is used to promote the breakup and homogeneous dispersion of bubbles inside the slurry through cavitation and acoustic flow.
8. The sterilization method according to claim 7, characterized in that, Step S5 specifically includes: S51, after completing the high-pressure stage, first shut down the microwave coupler and ultrasonic transducer ring array, and gradually reduce the heat flow of the steam jacket until the heat source is completely shut off. S52, after the heat source is turned off, starts the steam jacket cooling cycle, controls the cooling medium to gradually reduce the slurry temperature at a cooling rate of ≤1.5℃ / min, and calculates the temperature difference between various points of the slurry in real time through multi-point temperature sensors. When the temperature difference is greater than 5℃, the stirring roller is automatically triggered to expand slightly to assist in temperature uniformity. S53, during the cooling cycle, the inert micro-nano bubble injection system is activated to dissolve nitrogen or carbon dioxide into the slurry at low pressure. The high specific surface area of the micro-nano bubbles is used to achieve rapid heat exchange of the slurry, while the displacement effect inhibits the damage of residual oxygen to the degree of fiber polymerization. S54, when the overall temperature of the slurry drops to 85~90℃ and the temperature difference at any point is ≤5℃, the automatic discharge mechanism is activated to discharge the slurry. During the discharge process, the CIP / SIP cleaning pipeline is pre-flushed. After completing the discharge and cleaning process, S55 automatically generates an electronic batch record. The record includes the F-value curve, temperature distribution data, and stirring torque curve of the entire sterilization process, and is uploaded to the factory database through the traceability information module.
9. A sterilization container, characterized in that, For implementing the sterilization method according to any one of claims 1 to 8, the sterilization tank comprises: The tank and the vacuum system connected to it are used for degassing bio-based fiber pulp. A steam jacket, installed on the outer wall of the tank, is used for uniform heating and cooling of the tank. Microwave couplers and ultrasonic transducer arrays are installed inside the tank. The stirring roller, located at the bottom of the tank, has an adjustable expansion range to achieve slurry mixing and temperature uniformity; Multiple temperature sensors and torque monitoring modules distributed inside the tank are used for process status monitoring; An inert micro / nano bubble injection system connected to the tank is used for cooling and inhibiting oxidative degradation of the slurry; An automatic feeding mechanism and a CIP / SIP cleaning system are used for material discharge and online cleaning.