Pet food freeze-drying device

Abstract

The invention discloses a pet food freeze-drying device, which belongs to the technical field of freeze-drying, and comprises a control system, and a vacuum system, a cold trap and a drying system which are in communication connection with the control system. Through the intelligent temperature control technology, the fuzzy self-adaptive PID control algorithm is applied, the heating and cooling power is automatically adjusted according to material characteristics and real-time temperature data to achieve accurate control over the temperature, it is ensured that temperature changes can accurately meet the freeze-drying requirements of different materials, the temperature control accuracy is improved to + / -0.5 DEG C, and the freeze-drying efficiency is improved. The problem of quality damage caused by improper temperature control of materials is effectively avoided, and high purity, high activity and high stability of freeze-dried products are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of freeze-drying, in particular to a pet food freeze-drying device. BACKGROUND

[0002] Freeze-drying technology, as an important drying method, plays an indispensable role in many fields such as biopharmaceuticals, food processing, scientific research experiments, etc. In the field of biopharmaceuticals, it can effectively preserve biologically active substances such as proteins, vaccines, etc., ensuring the effectiveness and stability of drugs; in the food processing industry, food processed by freeze-drying technology not only retains its nutrients, flavor and color to the greatest extent, but also has a long shelf life, making it convenient to store and transport; in scientific research experiments, freeze-drying technology can be used to process various samples, providing stable sample conditions for subsequent analysis and research.

[0003] Traditional freeze-drying machine technology has been relatively mature after long-term development and accumulation, and can basically meet some conventional freeze-drying needs. However, with the rapid development of modern science and technology and the increasingly fierce competition in various industries, higher requirements are put forward for the quality, production efficiency and cost control of freeze-dried products. In terms of quality, some high-end biopharmaceutical products have very high precision requirements for temperature, vacuum degree and other parameters during the freeze-drying process, and even slight deviations can affect the activity and efficacy of the drugs; the food industry expects freeze-dried products to be closer to the fresh state in terms of taste and nutrient retention. In terms of production efficiency, large-scale industrial production requires freeze-drying machines to quickly complete the freeze-drying process to improve productivity and meet market demand. Cost control cannot be ignored either, as rising energy prices and increasing raw material costs have prompted companies to seek more energy-efficient and efficient freeze-drying technology to reduce production costs and improve economic efficiency.

[0004] In order to adapt to the development trend, freeze-drying technology is constantly advancing towards intelligence, efficiency and energy saving. For example, Chinese patent application No. CN113566500A discloses a freeze-drying device for food processing with high freeze-drying efficiency. By setting corresponding mechanisms on the freeze-drying device, the residual heat of the food entering the freeze-drying device is effectively reduced, allowing the freeze-drying device to freeze faster, improving the use efficiency of the freeze-drying device and the freeze-drying effect of the food, avoiding the rapid deterioration of the food after packaging, and reducing the loss suffered by the manufacturer.

[0005] For example, Chinese patent application No. CN119826465A discloses a fast and efficient freeze-drying device that improves the processing efficiency of the material and the space utilization rate in the freeze-drying machine.

[0006] For example, Chinese utility model patent with publication number CN206078924U discloses a food vacuum dryer, which includes a rectangular shell, a sealing door, a vacuuming mechanism, a pressure gauge and a temperature control device. The sealing door is sealed on the opening of the sealed accommodating cavity of the rectangular shell through a hinge mechanism and a sealing and pressing device. The temperature control and vacuuming mechanism are simple, the equipment has a simple structure, low cost and good drying effect.

[0007] However, the aforementioned existing technologies suffer from a series of key problems, including inaccurate temperature control, low vacuum system efficiency, and unreasonable drying chamber design, due to the lack of advanced temperature control algorithms, the absence of intelligent control and protection measures in the vacuum system, the lack of uniform heating and monitoring feedback design in the drying chamber, and low levels of equipment integration and intelligence. Furthermore, they are designed only for specific types of materials or application scenarios, lacking broad applicability. Therefore, there is an urgent need to provide a freeze-drying device to solve these technical problems. Summary of the Invention

[0008] This invention aims to completely solve a series of key problems existing in current freeze dryers, such as inaccurate temperature control, low efficiency of the vacuum system, and unreasonable drying chamber design. By innovatively applying advanced technologies, it optimizes and upgrades each key component of the freeze dryer, thereby comprehensively improving its performance. Specifically: A pet food freeze-drying apparatus includes a control system, and a vacuum system, a cold trap, and a drying system that are communicatively connected to the control system. The control system includes a temperature control system and an intelligent control center. The temperature control system is configured to monitor the temperature of the drying chamber / cold trap in real time and dynamically adjust the heating / cooling power. It includes a temperature sensor, a PLC controller, a heating device, and a cooling device. The PLC controller has a built-in fuzzy adaptive PID control algorithm. The intelligent control center includes an industrial computer, a data storage unit, and a human-machine interface. It is configured to run the fuzzy adaptive PID control algorithm, store multiple sets of freeze-drying curves, display parameters in real time, and provide access control and fault alarms. The temperature sensor serves as the input signal to the PLC controller. The signal is processed by the fuzzy adaptive PID control algorithm built into the PLC controller. The drive module then drives the heating / cooling device based on the algorithm processing results, thus achieving closed-loop control.

[0009] Preferably, the vacuum system is configured to monitor the vacuum level in real time and automatically start and stop the pump, including a pump, a vacuum sensor, an intelligent regulating device, and an oil backflow prevention valve; The drying system includes a drying chamber, which is equipped with humidity and pressure sensors to monitor humidity and pressure changes in real time during the freeze-drying process.

[0010] Preferably, the specific steps of the fuzzy adaptive PID control algorithm are as follows: First, determine the temperature deviation e = Tset - Tactual. and the rate of change of temperature deviation Where Tset is the set temperature and Tactual is the real-time temperature; Then, the temperature deviation e and the rate of change of temperature deviation ec are fuzzified and divided into seven fuzzy subsets: negative large, negative medium, negative small, zero, positive small, positive medium, and positive large. The membership degree is determined according to the membership function. Next, fuzzy inference is performed based on the fuzzy rule base, which is built based on expert experience and experimental data; Next, the center of gravity method is used for clarification to obtain a precise control quantity, the formula for which is: ; Finally, the control quantity u is converted into a control signal for the heating and cooling equipment to achieve temperature regulation.

[0011] Preferably, the specific working process of the pet food freeze-drying device includes: After receiving the temperature data, the control system analyzes and processes the temperature data. Based on the preset freeze-drying temperature curve and the material's characteristic parameters, the fuzzy adaptive PID control algorithm automatically adjusts the heating and cooling power.

[0012] Preferably, the automatic adjustment includes: In the initial stage of freeze-drying, when rapid cooling is required, the fuzzy adaptive PID control algorithm increases the cooling power to lower the temperature. In the middle stage of freeze-drying, when temperature control is needed for sublimation drying, the fuzzy adaptive PID control algorithm adjusts the heating and cooling power according to the magnitude and trend of the temperature deviation to ensure that the temperature remains stable near the set value. In the later stage of freeze-drying, when slow heating is needed to complete the desorption drying, the fuzzy adaptive PID control algorithm gradually reduces the cooling power while slowly increasing the heating power to achieve a smooth temperature rise.

[0013] Preferably, the pump comprises a two-stage vacuum pump combination of a forestage pump and a poststage pump, wherein the forestage pump is selected as a vacuum pump with fast pumping speed and large pumping volume; and the poststage pump is selected as a vacuum pump capable of achieving high vacuum.

[0014] Preferably, the forestage pump is a rotary vane pump and the poststage pump is a molecular pump.

[0015] Preferably, the drying chamber is also equipped with multi-layer baffles, a heat equalization device, and a sealed chamber with an insulation layer. The baffles are welded to the walls of the sealed chamber, and the heat equalization plate is attached to the inner surface of the drying chamber.

[0016] Preferably, the guide plate is a V-shaped guide plate.

[0017] Preferably, the heat dissipation device is an aluminum heat-conducting plate.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: In terms of temperature control, this invention utilizes intelligent temperature control technology and applies a fuzzy adaptive PID control algorithm to automatically adjust the heating and cooling power based on material characteristics and real-time temperature data. This achieves precise temperature control, ensuring that temperature changes accurately match the freeze-drying requirements of different materials. The temperature control accuracy is improved to ±0.5℃, effectively avoiding quality damage caused by improper temperature control and guaranteeing the high purity, high activity, and high stability of freeze-dried products.

[0019] This invention targets vacuum systems and, through optimized design, employs a combination of two-stage vacuum pumps and intelligent vacuum monitoring and regulation devices to significantly improve pumping efficiency, reducing the time to reach the target vacuum level by more than 30%, thus meeting the demand for efficient freeze-drying in large-scale production, while simultaneously reducing energy consumption and production costs.

[0020] This invention redesigns the drying chamber's internal structure, adding multi-layered baffles and a heat equalization device to ensure uniform heating of the samples. Furthermore, it installs humidity and pressure sensors to enable real-time monitoring and feedback adjustments during the freeze-drying process. Based on the monitoring data, it automatically adjusts key parameters such as temperature and vacuum level, achieving intelligent control of the freeze-drying process and ensuring the consistency and stability of product quality for each batch. Ultimately, this invention achieves the comprehensive goals of improving freeze-dried product quality, shortening freeze-drying time, reducing energy consumption and production costs, enhancing product competitiveness in the market, and promoting the further development of freeze-drying technology. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] 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, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the pet food freeze-drying device according to Embodiment 1 of the present invention.

[0024] Figure 2 This is a schematic diagram of the pet food freeze-drying device according to Embodiment 2 of the present invention.

[0025] Figure 3 This is a schematic diagram of the pet food freeze-drying device according to Embodiment 3 of the present invention. Detailed Implementation

[0026] 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 a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0028] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" and "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0029] Example 1 See Figure 1 As shown, the present invention provides a freeze-drying device for pet food, the core principle of which is "low-temperature freezing + sublimation dehydration under vacuum". Therefore, the freeze-drying device includes a control system, as well as a vacuum system, a cold trap, and a drying system that are communicatively connected to the control system.

[0030] The cold trap is used to capture water vapor in the freeze-drying device. Its specific structure can adopt the conventional structure in the field, and the present invention does not limit it.

[0031] The vacuum system is configured to monitor the vacuum level in real time and automatically start and stop the pump. It includes the pump, vacuum sensor, intelligent regulating device, and oil backflow prevention valve. The vacuum sensor transmits the collected vacuum level data to the intelligent regulating device, which controls the pump's start and stop. The oil backflow prevention valve is connected in series between the pump and the cold trap to provide physical protection.

[0032] In this embodiment, the specific structure of the vacuum system can be set using conventional methods of existing technology, and will not be described in detail here.

[0033] The drying system includes a drying chamber, inside which temperature / humidity sensors (such as...) are installed. Figure 1 In this context, ① refers to a temperature sensor; ② refers to a humidity sensor) and a pressure sensor (such as...). Figure 1 (③ refers to pressure sensors) (the installation location and method of the sensors can adopt conventional settings of existing technology, which will not be elaborated here). These sensors can monitor humidity and pressure changes in real time during the freeze-drying process. The humidity sensor can accurately measure the water vapor content in the drying chamber, i.e., humidity data, while the pressure sensor can accurately acquire the pressure data in the drying chamber. The sensors transmit the monitored humidity and pressure data to the control system in real time, and the control system analyzes and processes this data. When abnormal changes occur in humidity or pressure, the control system will automatically adjust parameters such as temperature and vacuum. For example, if the humidity sensor detects an increase in humidity in the drying chamber, it indicates that the sublimation rate of the material is too fast or too slow, and the control system will adjust the temperature or vacuum accordingly to ensure that the sublimation rate of the water is at the optimal state. Through the above-mentioned real-time monitoring and feedback adjustment mechanism of the drying chamber, intelligent control of the freeze-drying process is realized, ensuring the stability of the freeze-drying process and the consistency of the product.

[0034] The control system includes a temperature control system and an intelligent control center. The temperature control system is configured to monitor the drying chamber / cold trap temperature in real time, dynamically adjust heating / cooling power, and achieve precise temperature control within ±0.5℃. The system includes a high-precision temperature sensor, a PLC controller, heating elements, and cooling elements. The PLC controller incorporates a fuzzy adaptive PID control algorithm. Heating elements include resistance wires / infrared sensors, and cooling elements include thermoelectric coolers / compressors. The temperature sensor serves as the input signal to the PLC controller, which processes the signal using the built-in fuzzy adaptive PID control algorithm. The drive module then drives the heating / cooling elements based on the algorithm's results, achieving closed-loop control.

[0035] The intelligent control center includes an industrial computer, data storage unit, and human-machine interface (such as a touchscreen). It is configured to run a fuzzy adaptive PID control algorithm, store multiple sets of freeze-drying curves, display parameters in real time (such as temperature, pressure, and humidity), and also features access control and fault alarm functions. The intelligent control center communicates with the PLC controller via Ethernet.

[0036] The pet food freeze-drying apparatus of this invention introduces an advanced fuzzy adaptive PID control algorithm, which combines the advantages of fuzzy control and PID control. Fuzzy control can perform fuzzy reasoning on the control rules based on the freeze-drying characteristics of the material and real-time temperature data, adaptively adjusting the parameters of the PID controller. High-precision temperature sensors are installed at key locations in the drying chamber and cold trap. These sensors have extremely high sensitivity and accuracy, enabling real-time and precise acquisition of temperature data, and transmitting the data to the control system in a high-speed and stable manner.

[0037] The specific steps of the fuzzy adaptive PID control algorithm of the present invention are as follows: First, determine the temperature deviation e = Tset - Tactual. and the rate of change of temperature deviation .

[0038] Where Tset is the set temperature and Tactual is the real-time temperature.

[0039] Then, the temperature deviation *e* and the rate of change of temperature deviation *ec* are fuzzified and divided into seven fuzzy subsets: negative large (NB), negative medium (NM), negative small (NS), zero (ZO), positive small (PS), positive medium (PM), and positive large (PB). The membership degree is then determined based on a membership function. For example, a trigonometric function can be used. For the temperature deviation *e*, if its value is 5℃ and the temperature range is set to -10℃ to 10℃, its membership degree in PS and PM can be determined.

[0040] Next, fuzzy inference is performed based on the fuzzy rule base. The fuzzy rule base is built based on expert experience and experimental data. For example, "If the temperature deviation e is PB and the rate of change of temperature deviation ec is PS, then the output control quantity is NB".

[0041] Next, the center of gravity method is used for clarification to obtain a precise control quantity, the formula for which is: , where u i For fuzzy output, μ i This corresponds to the membership degree.

[0042] Finally, the control quantity u is converted into a control signal for the heating and cooling equipment, thereby achieving precise temperature regulation.

[0043] The specific working process of the pet food freeze-drying device of the present invention includes: A fuzzy adaptive PID control algorithm is applied to automatically adjust the heating and cooling power based on material characteristics and real-time temperature data, achieving precise temperature control. High-precision temperature sensors are installed to quickly and accurately collect temperature data, providing a basis for algorithm adjustments and ensuring the quality of freeze-dried materials. In terms of specific device integration, the temperature sensor is connected to a PLC controller. The PLC controller has a built-in fuzzy adaptive PID control algorithm program, and its outputs are connected to the drive modules of both the heating and cooling devices, forming a complete temperature control closed loop. When the temperature sensor collects the real-time temperature, it transmits the signal to the PLC controller. The PLC controller performs calculations according to the specific steps of the fuzzy adaptive PID control described above, obtains the control signal, and transmits it to the drive module to drive the heating or cooling device, thereby regulating the temperature. Specifically: After receiving temperature data, the control system first analyzes and processes the data. Based on the preset freeze-drying temperature curve and the material's characteristic parameters, the fuzzy adaptive PID control algorithm automatically adjusts the heating and cooling power. In the initial stage of freeze-drying, when rapid cooling is required, the fuzzy adaptive PID control algorithm increases the cooling power to rapidly lower the temperature. In the middle stage of freeze-drying, when precise temperature control is needed for sublimation drying, the fuzzy adaptive PID control algorithm finely adjusts the heating and cooling power according to the magnitude and trend of temperature deviation to ensure the temperature remains stable near the set value. In the later stage of freeze-drying, when slow heating is needed to complete desorption drying, the fuzzy adaptive PID control algorithm gradually decreases the cooling power while slowly increasing the heating power to achieve a smooth temperature rise.

[0044] The pet food freeze-drying apparatus of this invention achieves precise temperature control through the aforementioned control feedback method, with a control accuracy of ±0.5℃, effectively ensuring the stability and accuracy of temperature during the freeze-drying process. Precise temperature control and a uniform heating environment ensure ideal drying conditions for the freeze-dried products. The fuzzy adaptive PID control algorithm enables the temperature to precisely adapt to the freeze-drying requirements of different materials, preventing temperature fluctuations from damaging material quality. In the biopharmaceutical field, precise temperature control helps maintain the bioactivity of bioactive substances such as proteins and enzymes, improving product purity and stability; in the food processing industry, a uniform heating environment helps maintain the good taste and nutritional components of food, preventing quality degradation.

[0045] To further verify the effectiveness of the present invention, this embodiment also conducts a temperature control experiment, specifically including: Select representative materials with different properties, such as biological samples (including protein solutions, cell samples, etc.) and food (such as fruit slices, small pieces of meat, etc.), and conduct freeze-drying experiments in the freeze dryer improved according to the present invention.

[0046] Different freeze-drying temperature profiles are set according to the characteristics of different materials. For example, for protein solutions, the initial freeze-drying process requires rapid cooling to -40°C, holding this temperature for a period of time, followed by slow heating to -20°C at a rate of 0.5°C / h for sublimation drying, and finally slow heating to 20°C to complete desorption drying. For fruit slices, the initial freeze-drying process involves cooling to -30°C, followed by sublimation drying at around -20°C, and finally heating to 30°C to complete desorption drying.

[0047] During the experiment, a fuzzy adaptive PID control algorithm was used for temperature control. A high-precision temperature sensor monitored the temperature of the material and the drying chamber in real time, and transmitted the temperature data to the control system. The control system automatically adjusted the heating and cooling power based on the preset temperature curve and the real-time temperature data.

[0048] Experimental results show that during the entire freeze-drying process, the temperature fluctuation of the material was strictly controlled within a very small range, and the deviation between the actual temperature and the preset temperature curve remained within ±0.5℃. Compared with freeze dryers using traditional PID control, the retention rate of effective components in products using the temperature control technology of this invention is increased by 15%-20%. For example, after freeze-drying a protein solution, the protein activity retention rate increased from about 70% using traditional methods to 85%-90%; after freeze-drying fruit slices, the retention rate of nutrients such as vitamin C was also significantly improved, and the taste was closer to that of fresh fruit.

[0049] Example 2 This embodiment also provides a pet food freeze-drying device, which differs from Embodiment 1 in that the vacuum system is optimized. The remaining structure and specific implementation are the same as in Embodiment 1, and will not be described in detail here. Figure 2 As shown, the optimization of the vacuum system specifically includes: A two-stage vacuum pump design is adopted, comprising a forestage pump and a poststage pump. The forestage pump is a vacuum pump with fast pumping speed and large pumping capacity (such as a rotary vane pump), mainly responsible for rapidly extracting a large amount of gas in the drying chamber during the initial stage of freeze-drying, so as to rapidly reduce the pressure in the drying chamber (e.g., from atmospheric pressure to 100 Pa). The poststage pump is a vacuum pump capable of achieving a high vacuum degree (such as a molecular pump), which further extracts the remaining gas after the pressure has been reduced to a certain level by the forestage pump, to achieve a higher vacuum degree (e.g., maintaining 1-2 Pa).

[0050] The intelligent vacuum monitoring and regulation device monitors the vacuum level in real time using high-precision vacuum sensors and transmits the data to the control system. Based on the target and real-time data, the control system automatically adjusts the operating status of the forepump and post-pump to maintain efficient operation of the vacuum system. This method achieves the required vacuum level faster than traditional vacuum systems, improves pumping efficiency, and meets the needs of large-scale production.

[0051] The other structures and specific implementation methods of the above-mentioned vacuum system are the same as those of the specific implementation method of Embodiment 1 above, and will not be repeated here.

[0052] The optimized vacuum system and intelligent control significantly shorten the freeze-drying time. The application of a two-stage vacuum pump combination and an intelligent vacuum monitoring and adjustment device greatly reduces the time to reach the target vacuum level, improving pumping efficiency. During the freeze-drying process, the two-stage vacuum pump combination rapidly reduces pressure through the upstream pump and maintains a high vacuum level through the downstream pump, significantly improving freeze-drying efficiency; the intelligent monitoring and adjustment device automatically optimizes the pump's operating status, shortening the time to reach the target vacuum level and improving efficiency by more than 30%.

[0053] To further verify the effectiveness of the present invention, this embodiment also conducts vacuum system performance testing, specifically including: The performance of a vacuum system employing a two-stage vacuum pump combination was tested. During the test, different vacuum requirements in the actual freeze-drying process were simulated, and the time required to reach different vacuum levels was recorded.

[0054] First, the initial pressure of the drying chamber was set to atmospheric pressure (approximately 101.3 kPa), and the time required for the conventional single vacuum pump system and the two-stage vacuum pump combination system of the present invention to reach different vacuum levels such as 100 Pa, 50 Pa, and 10 Pa were tested respectively.

[0055] Experiments show that a traditional single vacuum pump system takes approximately 30 minutes to reach a vacuum level of 100 Pa, approximately 60 minutes to reach 50 Pa, and approximately 120 minutes to reach 10 Pa. In contrast, the two-stage vacuum pump combination system of this invention takes only approximately 18 minutes to reach a vacuum level of 100 Pa, approximately 35 minutes to reach 50 Pa, and approximately 70 minutes to reach 10 Pa. Compared to a traditional single vacuum pump system, the time to reach the same vacuum level is reduced by approximately 40%.

[0056] Meanwhile, regarding the ultimate vacuum level, traditional single vacuum pump systems typically achieve only 5-10 Pa, while the ultimate vacuum level of the two-stage vacuum pump combination system of this invention can be increased to 1-2 Pa, an improvement of an order of magnitude. This not only effectively improves freeze-drying efficiency but also makes some freeze-drying processes with extremely high vacuum requirements possible.

[0057] Example 3 This embodiment also provides a pet food freeze-drying device, which differs from Embodiment 1 in that the drying chamber is optimized. The remaining structure and specific implementation are the same as in Embodiment 1, and will not be described in detail here. Figure 3 As shown, the optimization of the drying chamber specifically includes: Compared to existing drying chambers, this embodiment redesigns the internal structure of the drying chamber. In addition to the humidity sensor and pressure sensor from Embodiment 1, it also installs a multi-layered flow guide plate ①, a heat equalization device ③, and a sealed chamber ② with an insulation layer inside the drying chamber. The multi-layered flow guide plate ① guides the hot airflow to be evenly distributed within the drying chamber, avoiding localized overheating or underheating. The heat equalization device ③ uses a material with high thermal conductivity to further promote uniform heat transfer, ensuring that the sample is heated evenly during the drying process. The sealed chamber ② with an insulation layer maintains a sealed, low-pressure environment.

[0058] In one optional embodiment, the baffle plate may be, for example, a V-shaped baffle plate, and the heat spreader may be, for example, an aluminum heat-conducting plate. When the device of the present invention is in operation, humidity and pressure sensor data from the drying chamber are sent to a PLC controller. The PLC controller adjusts the temperature control system / vacuum system. The baffle plate is welded to the wall of the sealed chamber, and the heat spreader plate is attached to the inner surface of the drying chamber.

[0059] In this embodiment, the internal structure of the drying chamber is reconstructed, with the addition of multi-layer baffles and a heat equalization device to ensure uniform hot airflow and heat transfer, thus solving the problem of uneven sample heating. Furthermore, humidity and pressure sensors are installed to enable real-time monitoring and feedback adjustments during the freeze-drying process. Based on the monitoring data, key parameters such as temperature and vacuum level are automatically adjusted, achieving intelligent control of the freeze-drying process and ensuring the consistency and stability of product quality for each batch. Ultimately, this achieves the comprehensive goals of improving freeze-dried product quality, shortening freeze-drying time, reducing energy consumption and production costs, enhancing product competitiveness in the market, and promoting the further development of freeze-drying technology.

[0060] To further verify the effectiveness of the present invention, this embodiment also conducts a performance verification of the drying chamber, specifically including: Multiple high-precision temperature, humidity, and pressure monitoring points are evenly placed in the optimized drying chamber. These monitoring points are distributed in different locations within the drying chamber, including near the heating source, far from the heating source, and at different heights of the sample layer, in order to comprehensively monitor changes in environmental parameters within the drying chamber.

[0061] A freeze-drying experiment was conducted by uniformly placing a certain amount of sample in the drying chamber. During the freeze-drying process, data was collected in real time using temperature, humidity, and pressure sensors, and the data was transmitted to the control system.

[0062] Monitoring data shows that the temperature difference at different locations within the drying chamber was consistently controlled within ±1℃, indicating that the multi-layer baffles and heat equalization device effectively ensured uniform heating of the samples. Simultaneously, changes in humidity and pressure were promptly fed back to the control system. When abnormal fluctuations in humidity or pressure occurred, the control system reacted quickly, automatically adjusting parameters such as temperature and vacuum.

[0063] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A freeze-drying device for pet food, characterized in that, This includes a control system, as well as a vacuum system, cold trap, and drying system that are in communication with the control system; The control system includes a temperature control system and an intelligent control center. The temperature control system is configured to monitor the temperature of the drying chamber / cold trap in real time and dynamically adjust the heating / cooling power. It includes a temperature sensor, a PLC controller, a heating device, and a cooling device. The PLC controller has a built-in fuzzy adaptive PID control algorithm. The intelligent control center includes an industrial computer, a data storage unit, and a human-machine interface. It is configured to run the fuzzy adaptive PID control algorithm, store multiple sets of freeze-drying curves, display parameters in real time, and provide access control and fault alarms. The temperature sensor serves as the input signal to the PLC controller. The signal is processed by the fuzzy adaptive PID control algorithm built into the PLC controller. The drive module then drives the heating / cooling device based on the algorithm processing results, thus achieving closed-loop control.

2. The pet food freeze-drying apparatus according to claim 1, characterized in that, The vacuum system is configured to monitor the vacuum level in real time and automatically start and stop the pump, including the pump, vacuum sensor, intelligent adjustment device and oil backflow prevention valve; The drying system includes a drying chamber, which is equipped with humidity and pressure sensors to monitor humidity and pressure changes in real time during the freeze-drying process.

3. The pet food freeze-drying apparatus according to claim 2, characterized in that, The specific steps of the fuzzy adaptive PID control algorithm are as follows: First, determine the temperature deviation e = Tset - Tactual. and the rate of change of temperature deviation Where Tset is the set temperature and Tactual is the real-time temperature; Then, the temperature deviation e and the rate of change of temperature deviation ec are fuzzified and divided into seven fuzzy subsets: negative large, negative medium, negative small, zero, positive small, positive medium, and positive large. The membership degree is determined according to the membership function. Next, fuzzy inference is performed based on the fuzzy rule base, which is built based on expert experience and experimental data; Next, the center of gravity method is used for clarification to obtain a precise control quantity, the formula for which is: , where u i For fuzzy output, μ i For the corresponding membership degree; Finally, the control quantity u is converted into a control signal for the heating and cooling equipment to achieve temperature regulation.

4. The pet food freeze-drying apparatus according to claim 3, characterized in that, The specific working process of a pet food freeze-drying device includes: After receiving the temperature data, the control system analyzes and processes the temperature data. Based on the preset freeze-drying temperature curve and the material's characteristic parameters, the fuzzy adaptive PID control algorithm automatically adjusts the heating and cooling power.

5. A pet food freeze-drying apparatus according to claim 4, characterized in that, The automatic adjustment includes: In the initial stage of freeze-drying, when rapid cooling is required, the fuzzy adaptive PID control algorithm increases the cooling power to lower the temperature. In the middle stage of freeze-drying, when temperature control is needed for sublimation drying, the fuzzy adaptive PID control algorithm adjusts the heating and cooling power according to the magnitude and trend of the temperature deviation to ensure that the temperature remains stable near the set value. In the later stage of freeze-drying, when slow heating is needed to complete the desorption drying, the fuzzy adaptive PID control algorithm gradually reduces the cooling power while slowly increasing the heating power to achieve a smooth temperature rise.

6. The pet food freeze-drying apparatus according to claim 2, characterized in that, The pump is a two-stage vacuum pump combination consisting of a back pump and a back pump. The back pump is a vacuum pump with fast pumping speed and large pumping volume; the back pump is a vacuum pump capable of achieving high vacuum.

7. A pet food freeze-drying apparatus according to claim 6, characterized in that, The forestage pump is a rotary vane pump, and the poststage pump is a molecular pump.

8. A pet food freeze-drying apparatus according to claim 2, characterized in that, The drying chamber is also equipped with multiple layers of baffles, a heat equalization device, and a sealed chamber with an insulation layer. The baffles are welded to the walls of the sealed chamber, and the heat equalization plate is attached to the inner surface of the drying chamber.

9. A pet food freeze-drying apparatus according to claim 8, characterized in that, The guide vane is a V-shaped guide vane.

10. A pet food freeze-drying apparatus according to claim 8, characterized in that, The heat dissipation device is an aluminum heat-conducting plate.

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