Temperature control system for decocting and concentrating oyster enzymatic hydrolysate

Abstract

The application discloses a temperature control system for a boiling and concentrating process of oyster enzymatic hydrolysate, and belongs to the technical field of temperature control, and specifically comprises: inputting container parameters, material parameters and temperature control benchmarks; determining power proportion according to the parameters and controlling the heating of the bottom and the side wall heating element group, wherein the side wall heating element group is vertically divided into multiple heating sub-zones with independent control power; in the heating process, the ultrasonic transceiving unit is used to obtain the sound wave attenuation coefficient and sound wave propagation speed of each depth position, and local temperature values are collected simultaneously; the boiling sub-region type of the detection depth position near the bottom heated surface is determined in the pre-labeled boiling state determination graph; when an excessive boiling state is detected, the power of the corresponding side wall heating sub-zone is reduced and the total power of the bottom heating is increased; when the temperature deviation of each depth position from the benchmark is less than the threshold value within the maintenance time length, the heating power is turned off. The application can actively intervene in power distribution in the transition boiling critical stage, and maintain temperature control accuracy.

Description

Technical Field

[0001] This invention relates to the field of temperature control technology, and specifically to a temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate. Background Technology

[0002] Oyster enzymatic hydrolysate is an important intermediate product in the deep processing of oysters, and its boiling and concentration process is a key step affecting the quality of the final product. The core of boiling and concentration lies in the precise control of the material temperature inside the container. If the temperature is too low, the concentration efficiency will be insufficient, while if the temperature is too high, it will easily cause local overheating, leading to denaturation and inactivation of the active ingredients in the hydrolysate. In industrial-scale production, boiling and concentration containers typically use a combination of bottom and sidewall heating. By adjusting the input power of each heating element, the temperature distribution at different depths within the container is controlled, allowing the material to be concentrated within a preset temperature range.

[0003] In existing technologies, temperature control during the boiling and concentration process often employs a closed-loop feedback regulation method based on temperature sensors. Contact temperature sensors are installed at various depths within the container to collect local temperature values ​​in real time and compare them with the target temperature. The power output of the heating element is adjusted based on the temperature deviation. To further improve the response speed of temperature control, some solutions introduce container thermal inertia compensation or feedforward control strategies to adjust the heating power in advance to cope with changes in the thermal properties of the material as the concentration process progresses. Regarding boiling state monitoring, existing research has used ultrasound to detect the bubble content in the liquid to determine the intensity of boiling. Changes in the sound wave attenuation coefficient distinguish between the liquid phase and the gas-liquid two-phase region, providing auxiliary judgment for temperature control.

[0004] However, temperature sensor-based regulation relies on temperature deviations to adjust power only after they occur, failing to intervene in advance at the critical stage of boiling transition. Oyster hydrolysate contains high levels of protein and salt, resulting in significantly different boiling heat transfer characteristics compared to pure water. During concentration, the bottom heating surface easily transitions from nucleus boiling to film boiling via a brief transitional boiling phase. Over-boiling is a dangerous precursor to a sharp decline in heat transfer efficiency. Once film boiling begins, the heating surface is covered by a film of gas, preventing effective heat transfer to the material. The surface temperature rises sharply while the overall material temperature drops, completely disrupting the temperature control baseline. Current technology lacks methods for identifying this critical over-boiling stage and corresponding heating power zoning intervention methods, failing to proactively adjust the power distribution between the bottom and sidewall heating element groups before the boiling state deteriorates. Summary of the Invention

[0005] The purpose of this invention is to provide a temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate, and to solve the following technical problems:

[0006] Existing technologies lack the means to identify the critical state of excessive boiling during the boiling and concentration of oyster enzymatic hydrolysate, and cannot actively adjust the power distribution relationship between the bottom and side wall heating element groups before the boiling state deteriorates, which makes the temperature control benchmark easy to be destroyed.

[0007] The objective of this invention can be achieved through the following technical solutions: A temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate includes: The parameter input module is used to input the container parameters of the boiling and concentration container, the material parameters of the oyster enzymatic hydrolysate to be concentrated, and the temperature control benchmark for the concentration stage. The heating control module is used to determine a preset initial power ratio based on material parameters and container parameters, and control the bottom heating element group and the side wall heating element group to heat at the preset initial power ratio. The side wall heating element group is divided into multiple heating zones with independent control power in the vertical direction. The data acquisition module is used to acquire the sound wave attenuation coefficient and sound wave propagation speed at multiple depth locations through the ultrasonic transceiver unit during the heating process, and at the same time acquire the local temperature value at each depth location. The state determination module is used to determine the type of boiling sub-region where the detection depth position within a preset distance range of the bottom heated surface is located, based on the sound wave attenuation coefficient and the sound wave propagation speed, in a pre-calibrated boiling state determination diagram. The intervention control module is used to reduce the input power of the heating zone corresponding to a certain detection depth position and increase the total input power of the bottom heating element group when a certain detection depth position falls into the transition boiling sub-region. The termination judgment module is used to turn off the power to the bottom heating element group and the side wall heating element group when the deviation between the local temperature value at each depth position and the temperature control reference is less than the temperature deviation threshold within the preset temperature maintenance time.

[0008] As a further aspect of the present invention: the specific process of determining the preset initial power ratio based on material parameters and container parameters in the heating control module is as follows: Extract the initial protein concentration and initial salinity values ​​from the material parameters, and extract the container inner diameter and container wall thickness values ​​from the container parameters. Input the container inner diameter and container wall thickness values ​​into the container thermal response calculation program to obtain the heat flux density ratio between the bottom heating surface and the side heating surface of the boiling and concentration container. Input the initial protein concentration and initial salinity values ​​into the oyster hydrolysate thermophysical property reference table to obtain the hydrolysate thermal conductivity and specific heat capacity. Input the heat flux density ratio, hydrolysate thermal conductivity, and specific heat capacity into the power distribution calculation program. The power distribution calculation program outputs the power distribution ratio between the bottom heating element group and the side wall heating element group. Use the power distribution ratio as the preset initial power ratio.

[0009] As a further aspect of the present invention: the specific process by which the sidewall heating element group is divided into multiple independently controllable heating zones in the vertical direction in the heating control module is as follows: The temperature response delay at each depth position is obtained. The depth position where the difference in temperature response delay between adjacent depth positions exceeds a preset delay difference threshold is marked as a delay jump position. The delay jump position is used as the boundary position of adjacent heating zones in the vertical direction. Heating zones are divided along the vertical direction, and each heating zone covers a different temperature response delay range. Each heating zone consists of an independent electric heating element group and a power regulator. The midpoint of the height range of each heating zone is recorded as the zone depth position. The depth position of each zone is associated with the heating zone number and stored.

[0010] As a further aspect of the present invention: the specific process by which the ultrasonic transceiver unit acquires the sound wave attenuation coefficient and sound wave propagation speed at multiple depth locations in the data acquisition module is as follows: The ultrasonic transceiver unit contains multiple ultrasonic transceiver unit groups. The installation height of each ultrasonic transceiver unit group is aligned with the height center of each heating zone of the side wall heating element group. The ultrasonic transceiver unit group is controlled to transmit sweep frequency signals and synchronously receive transmitted waveforms. The sound wave attenuation coefficient is calculated based on the amplitude ratio of the received waveform to the transmitted waveform, and the sound wave propagation speed is calculated based on the phase difference between the received waveform and the transmitted waveform and the transmission distance, thus obtaining the sound wave attenuation coefficient and sound wave propagation speed at each depth position.

[0011] As a further aspect of the present invention, the specific process of the state determination module is as follows: Under different initial protein concentrations and initial salinities, heating is controlled and the acoustic attenuation coefficient and acoustic propagation velocity at the detection depth are acquired simultaneously. Boiling state is identified and labeled. The acoustic attenuation coefficient and acoustic propagation velocity at the same moment are associated with the state label as calibration data points. The data points are grouped according to the state label. The minimum and maximum values ​​of the acoustic attenuation coefficient and acoustic propagation velocity of each group are taken as the attenuation boundary and velocity boundary of the corresponding state. A planar coordinate system is established with the acoustic attenuation coefficient as the first coordinate axis and the acoustic propagation velocity as the second coordinate axis. The rectangular area enclosed by each state boundary is marked as the corresponding boiling sub-region, forming a boiling state determination map. The acoustic attenuation coefficient and acoustic propagation velocity at the real-time detection depth position are used as parameter point coordinates to locate the position of the parameter point coordinates in the boiling state determination map, and the sub-region type where the parameter point coordinates are located is determined as the boiling sub-region type where the detection depth position is located.

[0012] As a further aspect of the present invention: the specific process of reducing the input power of the heating zone corresponding to the detection depth position and increasing the total input power of the bottom heating element group in the intervention control module is as follows: The detection depth position entering the transition boiling sub-region is compared with the partition depth positions of each heating zone in the sidewall heating element group. The heating zones with overlapping partition depth positions are identified as the heating zones to be adjusted. The local temperature value sequence within a preset backtracking time before entering the transition boiling sub-region is extracted from the detection depth position. The temperature change slope of the local temperature value sequence is calculated. The temperature change slope is compared with a preset slope threshold group to determine the sidewall power reduction ratio. The current input power value of the heating zone to be adjusted is multiplied by the sidewall power reduction ratio to obtain the power reduction amount and is executed. The power reduction amount is divided by the current total input power value of the bottom heating element group to obtain the power compensation ratio. The power compensation ratio is multiplied by a preset compensation amplification factor to obtain the bottom power increase ratio. The current total input power value of the bottom heating element group is multiplied by the bottom power increase ratio to obtain the power increase amount and is executed.

[0013] As a further aspect of the present invention: in the intervention control module, the specific process of multiplying the current total input power value of the bottom heating element group by the bottom power increase ratio to obtain the power increase amount and then executing the increase is as follows: Continue to acquire the acoustic attenuation coefficient and acoustic propagation velocity at the detection depth location and map them to the boiling state determination map. Record the sub-region type where the parameter point coordinates are located. When the parameter point coordinates enter the nucleate boiling sub-region from the transition boiling sub-region and the number of consecutive sampling stops reaches the preset stable number, calculate the temperature fluctuation standard deviation of the local temperature value sequence at the detection depth location during the stop period. Compare the temperature fluctuation standard deviation with the preset standard deviation threshold group to determine the partition power recovery ratio and the bottom power recovery ratio. The input power of the heating zone to be adjusted is gradually restored to the value before it was reduced, and the total input power of the bottom heating element group is gradually restored to the value before it was increased. The restoration step size is determined by the power restoration ratio of the zone and the power restoration ratio of the bottom zone, respectively.

[0014] As a further aspect of the present invention, the specific process of the termination judgment module is as follows: Obtain the local temperature value sequence at each depth location within the preset temperature maintenance time, calculate the absolute value of the deviation between the local temperature value at each depth location and the corresponding target temperature value in the temperature control benchmark, and determine whether the intervention operation of reducing the input power of the heating zone and increasing the total input power of the bottom heating element group in the intervention control module has been performed when the absolute value of the deviation at all depth locations is less than the temperature deviation threshold within the preset temperature maintenance time. When no intervention operation has been performed, the power supply to the bottom heating element group and the side wall heating element group is turned off. When an intervention operation has been performed, the local temperature value sequence at each depth position after the most recent intervention operation is extracted and the standard deviation is calculated. When the standard deviation of all depth positions is less than the preset standard deviation threshold, the power supply to the bottom heating element group and the side wall heating element group is turned off.

[0015] The beneficial effects of this invention are: This invention acquires the acoustic attenuation coefficient and acoustic propagation velocity at multiple depths within a boiling and concentration vessel using an ultrasonic transceiver unit. Utilizing a pre-calibrated boiling state determination map, it identifies the type of boiling sub-region near the detection depth near the bottom heating surface in real time, enabling timely identification during the critical stage of over-boiling, where heat transfer efficiency drops sharply. When the acoustic parameters at the detection depth fall into the transitional boiling sub-region, the system automatically reduces the input power of the corresponding sidewall heating zone while simultaneously increasing the total input power of the bottom heating element group. By altering the heat flow distribution structure within the vessel, it actively intervenes in the boiling state evolution path, pulling the heating surface back to the nucleus boiling range before film boiling forms. The power adjustment is dynamically determined based on the slope of the local temperature change before the detection depth enters the transitional boiling sub-region, ensuring the intervention intensity matches the deterioration trend of the boiling state and avoiding excessive intervention that could disrupt the concentration process. The entire temperature control process revolves around the boiling state determination map, transforming the traditional passive feedback adjustment of temperature deviation into active power redistribution based on boiling phase critical identification, thus maintaining the deviation between the local temperature value at each depth location and the temperature control reference within a preset range. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the modules of the present invention. Detailed Implementation

[0018] 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.

[0019] Please see Figure 1 As shown, the present invention relates to a temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate, comprising: The parameter input module is used to input the container parameters of the boiling and concentration container, the material parameters of the oyster enzymatic hydrolysate to be concentrated, and the temperature control benchmark for the concentration stage. The heating control module is used to determine a preset initial power ratio based on material parameters and container parameters, and control the bottom heating element group and the side wall heating element group to heat at the preset initial power ratio. The side wall heating element group is divided into multiple heating zones with independent control power in the vertical direction. The data acquisition module is used to acquire the sound wave attenuation coefficient and sound wave propagation speed at multiple depth locations through the ultrasonic transceiver unit during the heating process, and at the same time acquire the local temperature value at each depth location. The state determination module is used to determine the type of boiling sub-region where the detection depth position within a preset distance range of the bottom heated surface is located, based on the sound wave attenuation coefficient and the sound wave propagation speed, in a pre-calibrated boiling state determination diagram. The intervention control module is used to reduce the input power of the heating zone corresponding to a certain detection depth position and increase the total input power of the bottom heating element group when a certain detection depth position falls into the transition boiling sub-region. The termination judgment module is used to turn off the power to the bottom heating element group and the side wall heating element group when the deviation between the local temperature value at each depth position and the temperature control reference is less than the temperature deviation threshold within the preset temperature maintenance time.

[0020] In a preferred embodiment of the present invention, the specific process of determining the preset initial power ratio based on material parameters and container parameters in the heating control module is as follows: First, extract the initial protein concentration and initial salinity values ​​from the material parameters. For example, the initial protein concentration of a batch of oyster hydrolysate is 5%, and the initial salinity is 2%. Then, extract the container inner diameter and container wall thickness values ​​from the container parameters. For example, the container inner diameter is 1200 mm, and the container wall thickness is 8 mm.

[0021] The container's inner diameter and wall thickness are input into a container thermal response calculation program. Based on the container's geometry and material thermal conductivity, the program establishes heat transfer models for the container's bottom and sidewalls. It then calculates the time required for both the bottom and sidewall heated surfaces to reach a preset temperature rise under a unit heating power input, thus obtaining the heat flux density ratio between the bottom and sidewall heated surfaces. This heat flux density ratio reflects the difference in the ability of the two heating elements to transfer heat to the material. For example, when the container bottom is thicker than the sidewalls, the heat flux density at the bottom is lower than that at the sidewalls, resulting in a heat flux density ratio less than 1. This means that more power needs to be allocated to the bottom to achieve synchronous heating with the sidewalls.

[0022] Simultaneously, the initial protein concentration value of 5% and the initial salinity value of 2% were entered into a pre-established thermophysical property comparison table for oyster enzymatic hydrolysate. This comparison table was compiled by conducting thermophysical property tests on oyster enzymatic hydrolysate samples with different combinations of protein concentration and salinity, recording the thermal conductivity and specific heat capacity of the hydrolysate under each concentration and salinity combination. For example, the enzymatic hydrolysate with a concentration of 5% and a salinity of 2% corresponds to a thermal conductivity of 0.55 W / m Kelvin and a specific heat capacity of 3.8 kJ / kg Kelvin.

[0023] Input the heat flux density ratio, thermal conductivity (0.55), and specific heat capacity (3.8) into the power distribution calculation program. Based on the principle of heat balance in heat transfer, and assuming the target heating rates of the bottom and sidewall heating elements are consistent, the program calculates the ratio of the required input power to the bottom heating element group and the sidewall heating element group, outputting a power distribution ratio, for example, 1:0.7, which is used as the preset initial power ratio. This preset initial power ratio is used to establish a reasonable power distribution relationship during the heating start-up phase, ensuring that the material temperature at each depth within the container approaches the temperature control reference at a coordinated rate.

[0024] In another preferred embodiment of the present invention, the specific process of dividing the sidewall heating element group into multiple independently controllable heating zones in the vertical direction in the heating control module is as follows: First, the temperature response delay at each depth is obtained. The temperature response delay refers to the time, measured in seconds, required for the local temperature at a given depth to rise from its initial temperature to a fixed temperature increase after a unit step heating power is applied to the material at that depth. The delay is obtained as follows: a calibration solution with the same initial protein concentration and salinity as the material to be concentrated is injected into the container. A step power is applied individually to each independently adjustable heating section of the bottom heating element group and the side wall heating element group. The temperature rise curve is recorded using contact temperature sensors at each depth. The number of seconds required for the temperature to rise by 10 degrees Celsius is read from the curve as the temperature response delay at that depth for that heating section.

[0025] Next, the delay amounts corresponding to different heights of the heating segments at each depth location and the sidewall heating element assembly are summarized to form a vertical temperature response delay distribution. Then, the delay difference between adjacent depth locations is calculated. For example, the delay at a depth of 500 mm is 12 seconds, and the delay at a depth of 600 mm is 18 seconds, with a difference of 6 seconds. Depth locations where the difference exceeds a preset delay difference threshold are marked as delay jump locations. The preset delay difference threshold is 1.5 times the arithmetic mean of the delay differences between all adjacent depth locations. A delay jump location means that there is a significant difference in the response speed to heating power between the upper and lower regions at that location, typically at an interface where the material flow state or the degree of local phase change within the container changes.

[0026] The heating zones are divided vertically by using the delay transition position as the boundary between adjacent heating zones. For example, if a delay transition position is at a depth of 550 mm, then the area above this position is one heating zone and the area below it is another heating zone. Each heating zone covers a different temperature response delay range.

[0027] Each heating zone consists of an independent heating element group and a power regulator. The heating element group is a resistance wire embedded in the side wall of the container. After receiving control commands, the power regulator adjusts the input power of the resistance wire. The midpoint of the height range of each heating zone is recorded as the zone depth position. For example, if a zone ranges from 400 mm to 550 mm, the midpoint of the height range is 475 mm. This value is the zone depth position. The zone depth position of 475 mm is associated with the heating zone number, such as zone 3, and stored for subsequent intervention control module calls.

[0028] By dividing the heating zones by delaying the transition position, the material temperature response characteristics within each zone are made nearly uniform. Subsequent power adjustments are then executed uniformly across the entire zone, improving the specificity of temperature control.

[0029] In another preferred embodiment of the present invention, the specific process of acquiring the sound wave attenuation coefficient and sound wave propagation speed at multiple depth positions through the ultrasonic transceiver unit in the data acquisition module is as follows: The ultrasonic transceiver unit comprises multiple sets of ultrasonic transceiver unit groups, each consisting of one ultrasonic transmitting terminal and one ultrasonic receiving terminal. The ultrasonic transmitting and receiving terminals are installed opposite each other on opposite sides of the same height layer of the sidewall of the boiling and concentrating vessel, with their installation positions ensuring the transmission path passes through the center of the horizontal cross-section of that height layer. The installation height of each ultrasonic transceiver unit group is aligned with the height center of each heating zone of the sidewall heating element group. For example, if the height center of zone 3 is at a depth of 475 mm, then the corresponding ultrasonic transceiver unit group will also be installed at a depth of 475 mm.

[0030] During the heating process, each group of ultrasonic transceiver units is controlled to sequentially transmit swept-frequency signals from the bottom layer to the top layer and simultaneously receive transmitted waveforms. The center frequency range of the swept-frequency signals is selected within the frequency range where ultrasound is sensitive to gas-liquid two-phase media, for example, a center frequency of 1 MHz to 5 MHz. The transmitted ultrasonic pulses pass through the oyster enzymatic hydrolysate inside the container and are received by the receiving terminal on the opposite side. The transmission and reception times of each group of ultrasonic transceiver units are staggered, and a fixed time interval is set between the transmission start times of adjacent groups, for example, 200 milliseconds, to avoid signal crosstalk between different groups.

[0031] Compared to the original transmitted waveform, the transmitted waveform recorded by the receiving terminal shows amplitude attenuation and phase shift. The acoustic attenuation coefficient reflects the degree of energy loss of ultrasound waves as they pass through materials, while the acoustic propagation speed reflects how fast the ultrasound waves propagate within the material. Both parameters are highly sensitive to the content and distribution of bubbles within the material. When the material is in a pure liquid phase, the acoustic attenuation coefficient is low and the propagation speed is high. When a large number of bubbles appear in the material, the sound waves are scattered and reflected at the gas-liquid interface, increasing the attenuation coefficient and decreasing the propagation speed.

[0032] The sound wave attenuation coefficient is calculated as follows: Extract the initial amplitude from the received waveform and the corresponding transmitted amplitude from the transmitted waveform. Calculate the ratio of the received amplitude to the transmitted amplitude. Take the logarithm of this ratio to base 10, multiply by 20, and take the positive value to obtain the sound wave attenuation coefficient, measured in decibels (dB). For example, if the transmitted amplitude is 10 volts and the received amplitude is 0.5 volts, the ratio is 0.05. Taking the logarithm and multiplying by 20 yields a sound wave attenuation coefficient of 26 dB. The sound wave propagation speed is calculated as follows: Extract the arrival time of the initial wave from the received waveform and the transmission time from the transmitted waveform. Calculate the time difference between the two, i.e., the propagation time of the sound wave in the material. Divide the straight-line distance between the transmitting and receiving terminals by the propagation time to obtain the sound wave propagation speed, measured in meters per second (m / s). For example, if the transmission distance is 0.8 meters and the propagation time is 5.3 x 10^-5 seconds, the propagation speed is approximately 1509 m / s.

[0033] Each ultrasonic transceiver unit group completes one transmission and reception cycle in each sampling period, for example, 2 seconds. Each sampling period obtains a set of sound wave attenuation coefficients and sound wave propagation speeds at that depth location. Multiple consecutive sampling periods form a sequence of sound wave attenuation coefficients and sound wave propagation speeds, which are then used by the status determination module.

[0034] In another preferred embodiment of the present invention, the specific process of the state determination module is as follows: The calibration of the boiling state determination chart needs to be completed before formal production. Multiple batches of calibration samples are sequentially injected into the boiling and concentration vessel, each batch having a different combination of initial protein concentration and initial salinity values. For example, the first batch of calibration samples has an initial protein concentration of 3% and an initial salinity of 1.5%. The second batch has an initial protein concentration of 5% and an initial salinity of 2%. The third batch has an initial protein concentration of 7% and an initial salinity of 2.5%. The injection volume of each batch of calibration samples is the same as that of a normal production batch.

[0035] Each batch of calibration samples is heated, with the bottom heating element group and side wall heating element group controlling the power output to gradually increase, causing the calibration samples to gradually enter a boiling state from room temperature, and then gradually increasing the intensity of boiling until film boiling occurs. Throughout the heating process, the acoustic attenuation coefficient and acoustic propagation velocity at the detection depth are simultaneously acquired by an ultrasonic transceiver unit group installed within a preset distance range above the bottom heated surface, for example, 10 mm to 30 mm above the heated surface.

[0036] Simultaneously, continuous imaging of the detection depth position is achieved through an observation window installed on the side wall of the boiling and concentration vessel, at a frame rate of, for example, 60 frames per second. The operator observes the bubble morphology and liquid film coverage of the heated surface frame by frame, labeling the state according to classical criteria of boiling heat transfer. The criterion for nucleate boiling is the presence of isolated bubble nucleation points on the heated surface, with bubbles periodically forming and detaching, and the heated surface consistently wetted by liquid. The criterion for over-boiling is the merging of some bubbles to form gas masses, with intermittent liquid film rupture occurring in localized areas of the heated surface. The criterion for film boiling is that the heated surface is continuously covered by a gas film, preventing liquid contact with the heated surface. Each frame of the image is labeled with a state tag indicating either nucleate boiling, transitional boiling, or film boiling.

[0037] The sound wave attenuation coefficient and sound wave propagation speed at the same sampling moment are associated with the corresponding state label to form a calibration data point. For example, if the sound wave attenuation coefficient is 18 dB and the sound wave propagation speed is 1450 m / s at a certain moment, and the boiling state of the corresponding image frame is the nucleus boiling state, then the calibration data point is recorded as 18 dB, 1450 m / s, and nucleus boiling state.

[0038] All calibration data points for all calibration samples under different heating powers were collected and divided into three groups according to their state labels. In the nucleus boiling state group, the minimum and maximum acoustic attenuation coefficients (8 dB and 22 dB) were taken as the nucleus boiling attenuation boundaries, and the minimum and maximum acoustic propagation speeds (1380 m / s and 1520 m / s) were taken as the nucleus boiling velocity boundaries. In the transition boiling state group, the minimum and maximum acoustic attenuation coefficients (20 dB and 35 dB) were taken as the transition boiling attenuation boundaries, and the minimum and maximum acoustic propagation speeds (1200 m / s and 1400 m / s) were taken as the transition boiling velocity boundaries. In the film boiling state group, the minimum and maximum acoustic attenuation coefficients (33 dB and 50 dB) were taken as the film boiling attenuation boundaries, and the minimum and maximum acoustic propagation speeds (800 m / s and 1220 m / s) were taken as the film boiling velocity boundaries.

[0039] A planar coordinate system is established with the sound wave attenuation coefficient as the abscissa and the sound wave propagation speed as the ordinate. The rectangular region bounded by the nucleus boiling attenuation boundary (8 dB to 22 dB) and the nucleus boiling velocity boundary (1380 m / s to 1520 m / s) is designated as the nucleus boiling sub-region. The rectangular region bounded by the transition boiling attenuation boundary (20 dB to 35 dB) and the transition boiling velocity boundary (1200 m / s to 1400 m / s) is designated as the transition boiling sub-region. The rectangular region bounded by the film boiling attenuation boundary (33 dB to 50 dB) and the film boiling velocity boundary (800 m / s to 1220 m / s) is designated as the film boiling sub-region. These three sub-regions together constitute the boiling state determination diagram.

[0040] During the real-time concentration process, the acoustic attenuation coefficient and acoustic propagation speed at the detection depth position acquired in real time by the ultrasonic transceiver unit are used as parameter point coordinates. For example, if the acoustic attenuation coefficient is 28 dB and the acoustic propagation speed is 1280 m / s, the position of the parameter point coordinates in the boiling state determination map is located. If the coordinates fall within the transition boiling sub-region, the boiling sub-region type where the detection depth position is currently located is determined to be the transition boiling sub-region, and the result is output to the intervention control module.

[0041] In another preferred embodiment of the present invention, the specific process of reducing the input power of the heating zone corresponding to the detection depth position and increasing the total input power of the bottom heating element group in the intervention control module is as follows: When the state determination module outputs a detection depth position that enters the transition boiling sub-region, the intervention control module first compares this detection depth position with the partition depth positions of each heating zone in the sidewall heating element group. The partition depth position is the midpoint of the height range of each heating zone; for example, the partition depth position of heating zone 3 is 475 mm, and the partition depth position of heating zone 4 is 625 mm. The detection depth position comes from the ultrasonic transceiver unit group within a preset distance range of the bottom heated surface, such as 20 mm above the heated surface. If the detection depth position is 478 mm, it is closest to the partition depth position of heating zone 3 (475 mm), and the two are considered to coincide, thus determining heating zone 3 as the heating zone to be adjusted.

[0042] Next, the local temperature value sequence at the detection depth location within a preset backtracking time before entering the transition boiling sub-region is extracted from the data stored in the data acquisition module. The preset backtracking time is 30 seconds, meaning that the local temperature values ​​are extracted within 30 seconds before the current judgment time. If the sampling period is 2 seconds, the local temperature value sequence contains 15 temperature data points. The temperature change slope of this sequence is calculated. The temperature change slope is obtained by linearly fitting the sequence using the least squares method, reflecting the rate of temperature rise at that location before entering the transition boiling state. For example, if the temperature values ​​of a certain sequence are successively 98.2 degrees Celsius, 98.5 degrees Celsius, 98.9 degrees Celsius to 102.5 degrees Celsius, the fitted slope is 0.14 degrees Celsius per second.

[0043] The calculated temperature change slope is compared with a preset slope threshold set. The preset slope threshold set consists of multiple slope ranges determined based on statistical analysis of historical batch data. For example, the slope range is divided into three intervals: a low slope range of 0°C to 0.1°C per second, a medium slope range of 0.1°C to 0.2°C per second, and a high slope range of over 0.2°C per second. Each interval corresponds to a sidewall power reduction percentage: 10% for the low slope range, 15% for the medium slope range, and 20% for the high slope range. A larger temperature change slope indicates a faster temperature buildup on the heated surface, increasing the risk of transitional boiling deteriorating into film boiling. Therefore, a greater reduction in the power of the sidewall heating zone is needed to decrease local heating intensity. In the example above, the slope is 0.14°C per second, falling within the medium slope range, and the determined sidewall power reduction percentage is 15%.

[0044] Obtain the current input power value of the heating zone to be adjusted. For example, if the current input power of heating zone 3 is 8 kW, multiply it by 15% to get a power reduction of 1.2 kW. Control the power regulator of this heating zone to reduce the input power by 1.2 kW, and the reduced power is 6.8 kW.

[0045] Then, calculate the power increase of the bottom heating element group. Obtain the current total input power value of the bottom heating element group, for example, 20 kW. Divide the power reduction of 1.2 kW by the total bottom input power of 20 kW to obtain a power compensation ratio of 0.06. Multiply the power compensation ratio by the preset compensation amplification factor, which is 1.5, to obtain a bottom power increase ratio of 0.09. Multiply the current total input power value of the bottom heating element group of 20 kW by 0.09 to obtain a power increase of 1.8 kW, and control the bottom heating element group to increase the total input power to 21.8 kW. The purpose of a compensation amplification factor greater than 1 is not only to fully compensate for the heat reduction of the sidewalls, but also to additionally increase the bottom heat input to form stronger bubble disturbance at the bottom of the container, prompting the heated surface to quickly recover from the transition boiling state to the nucleation boiling state.

[0046] In the next sampling cycle after the power adjustment is completed, the intervention control module continues to acquire the acoustic attenuation coefficient and acoustic propagation velocity at the detection depth location through the data acquisition module, and maps them to the boiling state determination map, recording the sub-region type where the parameter point coordinates are located. If the parameter point coordinates are still in the transition boiling sub-region, the current power allocation state remains unchanged. When the parameter point coordinates move from the transition boiling sub-region to the nucleus boiling sub-region, the number of consecutive samplings in the nucleus boiling sub-region is counted. This is done once per sampling cycle. If the number of consecutive samplings reaches the preset stable number (e.g., 10 times, meaning the parameter point is in the nucleus boiling sub-region for 10 consecutive sampling cycles, totaling 20 seconds), the boiling state is considered to have stabilized and recovered, and the power recovery operation can be initiated.

[0047] Before initiating power recovery, the local temperature value sequence at the detection depth location within these 10 sampling periods is extracted, and the standard deviation of the temperature fluctuation in this sequence is calculated. The standard deviation of temperature fluctuation reflects the uniformity of the temperature field after recovery; the smaller the standard deviation, the more stable the temperature. The calculated standard deviation of temperature fluctuation is compared with a preset standard deviation threshold group, which is divided into three intervals, for example: low fluctuation interval (0°C to 0.5°C), medium fluctuation interval (0.5°C to 1.0°C), and high fluctuation interval (above 1.0°C). Each interval corresponds to a set of partition power recovery ratios and bottom power recovery ratios. The low fluctuation interval corresponds to a partition power recovery ratio of 5% per step and a bottom power recovery ratio of 4% per step. The medium fluctuation interval corresponds to a partition power recovery ratio of 3% per step and a bottom power recovery ratio of 2.5% per step. The high fluctuation interval corresponds to a partition power recovery ratio of 2% per step and a bottom power recovery ratio of 1.5% per step. The greater the temperature fluctuation, the slower the recovery step size, to avoid repeated boiling states caused by excessively rapid recovery. Assuming the standard deviation of temperature fluctuation is 0.6 degrees Celsius, falling within the medium fluctuation range, the power recovery ratio for the partition is determined to be 3% per step, and the power recovery ratio for the bottom is 2.5% per step.

[0048] The recovery process employs a cycle-by-cycle step-by-step approach. In each sampling cycle, the input power of the heating zone to be adjusted increases by the zone power recovery ratio, while the total input power of the bottom heating element group decreases by the bottom power recovery ratio. For example, if the power of the heating zone to be adjusted is reduced to 6.8 kW and the power before reduction is 8 kW, each increment is 3% of the current power, recovering to 8 kW after several steps. Simultaneously, the bottom heating element group decreases, recovering from an increased 21.8 kW to 20 kW. The recovery step size is dynamically determined by the aforementioned ratios until both return to their pre-intervention values, at which point the recovery operation ends.

[0049] In another preferred embodiment of the present invention, the specific process of the termination determination module is as follows: As the concentration process progresses into its later stages, the local temperature values ​​at each depth gradually approach the target temperature value set by the temperature control benchmark. For example, the temperature control benchmark specifies that the target temperature at each depth is 105 degrees Celsius during the later stages of concentration. The termination determination module acquires a sequence of local temperature values ​​at each depth within a preset temperature maintenance duration during each sampling cycle. The preset temperature maintenance duration is 180 seconds, meaning that the temperature at each depth must remain stable near the target temperature for 180 consecutive seconds.

[0050] For each depth location, the temperature sequence of that location within the last 180 seconds is compared one by one with the target temperature of 105 degrees Celsius. The absolute value of the deviation between the temperature value of each sampling point and 105 degrees Celsius is calculated. For example, the temperature values ​​at depth location 475 mm within the last 180 seconds are 105.1 degrees Celsius, 105.3 degrees Celsius, and 104.9 degrees Celsius, with absolute deviation values ​​of 0.1 degrees Celsius, 0.3 degrees Celsius, and 0.1 degrees Celsius, respectively. If the absolute value of the deviation of all sampling points at all depth locations within these 180 seconds is less than the temperature deviation threshold (which is set to 0.5 degrees Celsius), then proceed to the next step of the judgment.

[0051] At this point, it is determined whether a power intervention operation was performed by the intervention control module during the concentration process. This determination is based on the intervention event marker record. If no intervention event marker is found in the record, it indicates that the boiling state throughout the concentration process remained in the nucleate boiling sub-region, without over-boiling, and the temperature control was stable. In this case, the power to the bottom heating element group and the side wall heating element group is directly turned off, and the concentration process ends.

[0052] If the logs show an intervention event marker, it indicates that over-boiling occurred during the concentration process and power intervention was implemented. Further verification of the temperature field recovery quality after intervention is needed. Extract the local temperature value sequence for each depth location within the last 180 seconds after the most recent intervention, and calculate the standard deviation of the temperature sequence for each depth location. For example, the standard deviation of the temperature sequence within 180 seconds at a depth of 475 mm is 0.2 degrees Celsius, and the standard deviation at a depth of 625 mm is 0.3 degrees Celsius. When the standard deviation of all depth locations is less than a preset standard deviation threshold (0.4 degrees Celsius), it indicates that the temperature field is sufficiently uniform and stable, with no residual thermal stress disturbances, and the boiling state has been completely restored. At this point, the power to the bottom heating element group and the side wall heating element group is turned off, and the concentration process ends. If the standard deviation at any depth location exceeds the preset standard deviation threshold, the current power state is maintained and the monitoring time is extended until the condition is met.

[0053] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate, characterized in that, include: The parameter input module is used to input the container parameters of the boiling and concentration container, the material parameters of the oyster enzymatic hydrolysate to be concentrated, and the temperature control benchmark for the concentration stage. The heating control module is used to determine a preset initial power ratio based on material parameters and container parameters, and control the bottom heating element group and the side wall heating element group to heat at the preset initial power ratio. The side wall heating element group is divided into multiple heating zones with independent control power in the vertical direction. The data acquisition module is used to acquire the sound wave attenuation coefficient and sound wave propagation speed at multiple depth locations through the ultrasonic transceiver unit during the heating process, and at the same time acquire the local temperature value at each depth location. The state determination module is used to determine the type of boiling sub-region where the detection depth position within a preset distance range of the bottom heated surface is located, based on the sound wave attenuation coefficient and the sound wave propagation speed, in a pre-calibrated boiling state determination diagram. The intervention control module is used to reduce the input power of the heating zone corresponding to a certain detection depth position and increase the total input power of the bottom heating element group when a certain detection depth position falls into the transition boiling sub-region. The termination judgment module is used to turn off the power to the bottom heating element group and the side wall heating element group when the deviation between the local temperature value at each depth position and the temperature control reference is less than the temperature deviation threshold within the preset temperature maintenance time.

2. The temperature control system for the oyster enzymatic hydrolysate boiling and concentration process according to claim 1, characterized in that, In the heating control module, the specific process of determining the preset initial power ratio based on material parameters and container parameters is as follows: Extract the initial protein concentration and initial salinity values ​​from the material parameters, and extract the container inner diameter and container wall thickness values ​​from the container parameters. Input the container inner diameter and container wall thickness values ​​into the container thermal response calculation program to obtain the heat flux density ratio between the bottom heating surface and the side heating surface of the boiling and concentration container. Input the initial protein concentration and initial salinity values ​​into the oyster hydrolysate thermophysical property reference table to obtain the hydrolysate thermal conductivity and specific heat capacity. Input the heat flux density ratio, hydrolysate thermal conductivity, and specific heat capacity into the power distribution calculation program. The power distribution calculation program outputs the power distribution ratio between the bottom heating element group and the side wall heating element group. Use the power distribution ratio as the preset initial power ratio.

3. The temperature control system for the oyster enzymatic hydrolysate boiling and concentration process according to claim 2, characterized in that, In the heating control module, the specific process of dividing the sidewall heating element group into multiple independently controllable heating zones in the vertical direction is as follows: The temperature response delay at each depth position is obtained. The depth position where the difference in temperature response delay between adjacent depth positions exceeds a preset delay difference threshold is marked as a delay jump position. The delay jump position is used as the boundary position of adjacent heating zones in the vertical direction. Heating zones are divided along the vertical direction, and each heating zone covers a different temperature response delay range. Each heating zone consists of an independent electric heating element group and a power regulator. The midpoint of the height range of each heating zone is recorded as the zone depth position. The depth position of each zone is associated with the heating zone number and stored.

4. The temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate according to claim 1, characterized in that, In the data acquisition module, the specific process of obtaining the sound wave attenuation coefficient and sound wave propagation speed at multiple depth positions through the ultrasonic transceiver unit is as follows: The ultrasonic transceiver unit contains multiple ultrasonic transceiver unit groups. The installation height of each ultrasonic transceiver unit group is aligned with the height center of each heating zone of the side wall heating element group. The ultrasonic transceiver unit group is controlled to transmit sweep frequency signals and synchronously receive transmitted waveforms. The sound wave attenuation coefficient is calculated based on the amplitude ratio of the received waveform to the transmitted waveform, and the sound wave propagation speed is calculated based on the phase difference between the received waveform and the transmitted waveform and the transmission distance, thus obtaining the sound wave attenuation coefficient and sound wave propagation speed at each depth position.

5. The temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate according to claim 1, characterized in that, The specific process of the state determination module is as follows: Under different initial protein concentrations and initial salinities, heating is controlled and the acoustic attenuation coefficient and acoustic propagation velocity at the detection depth are acquired simultaneously. Boiling state is identified and labeled. The acoustic attenuation coefficient and acoustic propagation velocity at the same moment are associated with the state label as calibration data points. The data points are grouped according to the state label. The minimum and maximum values ​​of the acoustic attenuation coefficient and acoustic propagation velocity of each group are taken as the attenuation boundary and velocity boundary of the corresponding state. A planar coordinate system is established with the acoustic attenuation coefficient as the first coordinate axis and the acoustic propagation velocity as the second coordinate axis. The rectangular area enclosed by each state boundary is marked as the corresponding boiling sub-region, forming a boiling state determination map. The acoustic attenuation coefficient and acoustic propagation velocity at the real-time detection depth position are used as parameter point coordinates to locate the position of the parameter point coordinates in the boiling state determination map, and the sub-region type where the parameter point coordinates are located is determined as the boiling sub-region type where the detection depth position is located.

6. The temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate according to claim 1, characterized in that, In the intervention control module, the specific process of reducing the input power of the heating zone corresponding to the detection depth position and increasing the total input power of the bottom heating element group is as follows: The detection depth position entering the transition boiling sub-region is compared with the partition depth positions of each heating zone in the sidewall heating element group. The heating zones with overlapping partition depth positions are identified as the heating zones to be adjusted. The local temperature value sequence within a preset backtracking time before entering the transition boiling sub-region is extracted from the detection depth position. The temperature change slope of the local temperature value sequence is calculated. The temperature change slope is compared with a preset slope threshold group to determine the sidewall power reduction ratio. The current input power value of the heating zone to be adjusted is multiplied by the sidewall power reduction ratio to obtain the power reduction amount and is executed. The power reduction amount is divided by the current total input power value of the bottom heating element group to obtain the power compensation ratio. The power compensation ratio is multiplied by a preset compensation amplification factor to obtain the bottom power increase ratio. The current total input power value of the bottom heating element group is multiplied by the bottom power increase ratio to obtain the power increase amount and is executed.

7. The temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate according to claim 6, characterized in that, In the intervention control module, the specific process of multiplying the current total input power value of the bottom heating element group by the bottom power increase ratio to obtain the power increase amount and then executing the increase is as follows: Continue to acquire the acoustic attenuation coefficient and acoustic propagation velocity at the detection depth location and map them to the boiling state determination map. Record the sub-region type where the parameter point coordinates are located. When the parameter point coordinates enter the nucleate boiling sub-region from the transition boiling sub-region and the number of consecutive sampling stops reaches the preset stable number, calculate the temperature fluctuation standard deviation of the local temperature value sequence at the detection depth location during the stop period. Compare the temperature fluctuation standard deviation with the preset standard deviation threshold group to determine the partition power recovery ratio and the bottom power recovery ratio. The input power of the heating zone to be adjusted is gradually restored to the value before it was reduced, and the total input power of the bottom heating element group is gradually restored to the value before it was increased. The restoration step size is determined by the power restoration ratio of the zone and the power restoration ratio of the bottom zone, respectively.

8. The temperature control system for the boiling and concentration process of oyster enzymatic hydrolysate according to claim 1, characterized in that, The specific process of the termination judgment module is as follows: Obtain the local temperature value sequence at each depth location within the preset temperature maintenance time, calculate the absolute value of the deviation between the local temperature value at each depth location and the corresponding target temperature value in the temperature control benchmark, and determine whether the intervention operation of reducing the input power of the heating zone and increasing the total input power of the bottom heating element group in the intervention control module has been performed when the absolute value of the deviation at all depth locations is less than the temperature deviation threshold within the preset temperature maintenance time. When no intervention operation has been performed, the power supply to the bottom heating element group and the side wall heating element group is turned off. When an intervention operation has been performed, the local temperature value sequence at each depth position after the most recent intervention operation is extracted and the standard deviation is calculated. When the standard deviation of all depth positions is less than the preset standard deviation threshold, the power supply to the bottom heating element group and the side wall heating element group is turned off.

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