Microwave sterilization system and process based on 433MHz solid-state microwave source

Abstract

The present invention relates to the field of microwave sterilization technology, and specifically to a microwave sterilization system and process flow based on a 433MHz solid-state microwave source. It includes a reduced pressure feeding chamber, a preheating chamber, several groups of microwave processing modules, an insulation box, a cooling chamber and a reduced pressure discharging chamber connected in sequence; the microwave processing module includes a heating cavity, and a group of microwave heating components are respectively provided at the upper and lower ends of the heating cavity, and the microwave heating component includes a microwave source at the end, the microwave source is connected to the bell mouth through a waveguide, and the lower end of the bell mouth is connected to the heating cavity through a microwave window; the microwave source is a 433MHz solid-state microwave source. The present invention adopts a solid-state microwave source with a frequency of 433MHz as the main function part of the microwave sterilization system, which not only fully utilizes the greater penetration depth of 433MHz microwaves, but also reduces the floor space, reduces the length of the waveguide, and improves the controllability and stability of the system, laying a foundation for the widespread application of microwave sterilization systems based on 433MHz solid-state microwave sources.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave sterilization, and in particular to a microwave sterilization system and process flow based on a 433 MHz solid-state microwave source. Background Art

[0002] With the acceleration of the pace of modern life, the sales of traditional canned foods have declined and the growth has been weak. Take-out foods have occupied a huge market with their high freshness, good palatability and high quality. Although take-out foods are of high quality, they have a short shelf life and are difficult to store; canned foods have the advantages of a long shelf life and safety. How to combine the advantages of the two and improve product quality while increasing shelf life is a problem that needs to be solved urgently.

[0003] Food processed by microwave heating technology has good quality and long shelf life, but there are also problems such as uniformity and repeatability. Most microwave heating equipment currently has a frequency of 915MHz and 2450MHz. Due to the short wavelength, there is a problem of small penetration depth. The advantages of microwaves with a frequency of 433MHz are long wavelength and large penetration depth, but due to the large volume of the microwave source of the traditional magnetron, 433MHz microwave sources are rarely used in actual applications. At the same time, there are few designs for the 433MHz heating cavity, and related research is scarce, mainly focusing on applications in the medical field. However, the power of the 433MHz microwave source used for microwave therapy is relatively small, generally tens of watts, while the microwave power used for microwave sterilization is generally in the kilowatt level, which is 2 orders of magnitude different. In addition, microwave sterilization must have a complete system design to ensure food safety, and each step requires precise calculations to achieve the sterilization effect. These aspects are not involved in the application of 433MHz microwaves in the medical field.

[0004] In terms of food sterilization, the existing microwave sterilization equipment uses magnetron as microwave source, and the poor frequency stability leads to unstable heat type, resulting in poor repeatability of heating effect. Solid-state source is highly controllable and has high frequency stability. It can provide real-time feedback and adjustment of frequency, power (forward / reverse), phase, etc. during equipment operation. 915MHz and 2450MHz equipment are difficult to scale up industrially due to their small applicable cavity size. The cavity design of 433MHz equipment itself is industrial-scale, which is conducive to industrial scale-up. This provides a huge market for the widespread application of microwave sterilization systems with 433MHz solid-state microwave sources. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the traditional 915MHz and 2450MHz microwave sterilization equipment has the problem of small penetration depth due to its short wavelength; and since the microwave source of the traditional magnetron is large in size, the 433MHz microwave source is also less in practical application.

[0006] To solve the above problems, the present invention adopts a solid-state microwave source with a frequency of 433 MHz as the main working part of the microwave sterilization system, which not only fully utilizes the greater penetration depth of 433 MHz microwaves, but also reduces the footprint, reduces the length of the waveguide, and improves the controllability and stability of the system, laying the foundation for the widespread application of microwave sterilization systems based on 433 MHz solid-state microwave sources.

[0007] To achieve the above object, the present invention is specifically implemented through the following technical solutions: a microwave sterilization system based on a 433MHz solid-state microwave source, comprising a reduced pressure feeding chamber, a preheating chamber, a plurality of groups of microwave processing modules, an insulation box, a cooling chamber and a reduced pressure discharging chamber connected in sequence; the microwave processing system is composed of a plurality of microwave processing modules, and the thermal type of each heating cavity can be different by design, and the temperature difference between hot and cold spots of the food to be sterilized can be minimized by passing through a plurality of heating cavities; the reduced pressure feeding chamber, the preheating chamber, the microwave processing module, the insulation box, the cooling chamber and the reduced pressure discharging chamber are all provided with independent guide rails, which are connected to their respective motors;

[0008] The microwave processing module includes a heating cavity with a guide rail inside. The material is sterilized by microwave in the cavity. A group of microwave heating components are respectively provided at the upper and lower ends of the heating cavity. The microwave heating components include a microwave source at the end. The microwave source is connected to the bell mouth through a waveguide. The lower end of the bell mouth is connected to the heating cavity through a microwave window. The microwave source is a 433MHz solid-state microwave source. The height of the heating cavity is less than 175mm (about a quarter wavelength) and the width is less than 692mm (about one wavelength). The heating in this near-field area can have better uniformity.

[0009] The preheating chamber, microwave treatment system, insulation box, and cooling chamber are each equipped with a circulating water pump. The chambers are filled with soft water, and the upper part is air. The doors connecting the chambers are opened above the water level; each part is equipped with an independent water circulation system to control the temperature. Between each chamber, a servo motor is used to lift the material rack out of the water, and the servo motor is used to put the material rack on the guide rail, and then a compressed air cylinder is used to push the material rack to the back box; this completes the transition between the two boxes.

[0010] The microwave frequency used in the present invention is 433MHz, which has a greater penetration depth and can be used to treat foods of greater thickness. However, the use of a 433MHz microwave source for microwave therapy and microwave sterilization is very different. When used for microwave therapy, the power is relatively small, generally tens of watts, while the microwave power used for microwave sterilization is generally in the kilowatt range, which is 2 orders of magnitude different. If the frequency stability is poor during food sterilization, it will lead to unstable thermal type and poor repeatability of heating effect, which will have a fatal impact on the sterilization effect. Therefore, there are still many structures that need to be adjusted and many technologies that need to be studied when applying a 433MHz microwave source in the field of microwave sterilization.

[0011] Moreover, microwave therapy is generally considered to be a superficial thermal therapy method, which mainly uses the thermal effect of microwaves to achieve the effect of anti-inflammatory treatment of postoperative wounds. Microwave sterilization uses the thermal effect and non-thermal effect of microwaves (also referred to as the biological effect of microwaves. The non-thermal biological effect of microwaves means that there is no obvious temperature rise inside the organism, but it can produce a strong biological response, causing various physiological, biochemical and functional changes in the organism, leading to the death of bacteria, and achieving the purpose of sterilization.)

[0012] The main non-thermal effect mechanisms are as follows:

[0013] (1) Microorganisms have a selective absorption of microwaves. The main ingredients of food, such as starch and protein, have a relatively low absorption rate for microwaves, and the food itself heats up slowly. However, the microorganisms in the food generally contain more water and have a larger dielectric loss factor, which makes them easily absorb microwave energy, causing their internal temperature to rise sharply and be killed.

[0014] (2) Reduce water activity and destroy the living environment of microorganisms.

[0015] (3) Impact on cell membrane: Under high-frequency microwave fields, the cell membrane with a capacitive structure will be electrically broken down and ruptured, but the temperature will not rise significantly; the cell membrane will be mechanically damaged, causing the intracellular substances to leak out, affecting the growth and reproduction of bacteria; the ion flow induced by the microwave electromagnetic field will affect the charge distribution near the cell membrane, affect the ion channel, cause the membrane barrier function to be lost, and produce membrane dysfunction, thereby interfering with or destroying the normal metabolic function of the cell, resulting in bacterial growth inhibition, cessation or death.

[0016] (4) The cell wall is broken, and substances such as proteins and nucleic acids will penetrate into the body, leading to the death of microorganisms. Changes in the cell membrane and cell wall have been proven by cell microstructure analysis. Under transmission electron microscopy, the bacterial cells are deformed after microwave treatment, the gap between the cell wall and the cell membrane widens, wrinkles appear on the surface of the cell wall and are partially blurred, the contents of the cytoplasm are uneven, and the water content is reduced to 40%.

[0017] (5) From a biological point of view, microwaves cause the hydrogen bonds in the DNA and RNA structures in cells to relax, break and recombine, inducing gene mutations, chromosome 143 aberrations, etc., thereby interrupting the normal reproduction ability of cells.

[0018] (6) The dipole molecules rotate and tend to be arranged in a linear manner in the interactive electric field, thereby causing changes in the secondary and tertiary structures of the protein, leading to the death of bacterial microorganisms.

[0019] Therefore, using a 433MHz microwave source for food sterilization is not as simple as just heating, and controlling the stability of the system is not only about solving the problem of uneven heating, but requires a complete system design. For example, the present invention uses a series of designs such as software simulation, M-2 simulants to perform thermal type simulation to determine the stability of the thermal type, determine the hot and cold spots after determining the thermal type, insert a temperature sensor at the cold spot to measure the lowest temperature and temperature curve, and then adopts a solid-state microwave source to control the size of the waveguide to 533.4mm*266.7mm, the upper plane size of the bell mouth to 533.4mm*266.7mm, the lower plane size to 1066.8mm*266.7mm, and the height to 400mm, and the heating cavity to control the height to 100mm, the length to 1300mm, and the width to 300mm, to obtain the following: Figure 9-11 From the electric field simulation diagram of the equipment shown (energy distribution simulation), it can be seen that the electric field distribution of a single microwave processing module is very uniform, so the thermal effect and non-thermal effect of its microwave action will be very uniform, and thus the sterilization effect of the entire system will be very uniform.

[0020] Furthermore, there are movable metal sheets on the left and right sides of the loading rack, and the metal sheets are at the same height as the microwave heating cavity, so as to indirectly adjust the width of the heating cavity, thereby achieving the effect of adjusting the magnetic field distribution, and then playing the role of electric field regulation.

[0021] The microwave window in each microwave processing module can be designed to have different sizes, and the spacing of the metal sheets can be adjusted for different foods to change the actual heating width of the heating cavity, thereby achieving the effect of adjusting the width of the heating cavity and making the microwave heating more uniform.

[0022] Furthermore, the decompression feeding chamber includes a feeding front door and a feeding rear door. The front feeding front door is connected to the outside and the decompression feeding chamber, and a high-pressure cylinder is arranged below the front feeding front door. The chamber body is connected to a pressurizing device, such as but not limited to a pressurizing cylinder, and the feeding rear door is connected to the decompression feeding chamber and the preheating chamber. The ship lock design can complete the continuous feeding process when the whole system is under high pressure, thereby ensuring the continuity of the system operation.

[0023] Furthermore, the front end of the preheating chamber is a feeding rear door, the top is a preheating chamber sealing cover, a preheating chamber sealing ring is provided at the connection with the chamber body, the chamber body is connected to the pressurizing equipment and the circulating water pump; the rear end is connected to the heating cavity of the microwave processing module at the front end through a pipeline; the design of the preheating chamber can reduce the temperature difference of microwave heating and reduce the unevenness of microwave heating. At the same time, the preheating temperature of this patent is less than or equal to 50°C, which basically does not change the quality of food.

[0024] Furthermore, the front end of the heat preservation box is connected to the heating cavity of the microwave processing module at the end through a pipeline, the top is a heat preservation box sealing cover, and a heat preservation box sealing ring is provided at the connection with the box body, the rear end is connected to the front end of the cooling chamber 5 through a pipeline, and the bottom is connected to the circulating water pump 7. The traditional thermal sterilization is adopted to make the microwave cold point achieve the required sterilization effect. The microwave sterilization and thermal sterilization are used together to reduce the thermal sterilization time and improve the food quality while meeting the sterilization requirements.

[0025] Furthermore, the front end of the cooling chamber is connected to the rear end of the heat preservation box through a pipeline, the top is a cooling chamber sealing cover, and a cooling chamber sealing ring is provided at the connection with the chamber body, and the rear end is connected to the decompression discharge chamber through the discharge front door of the decompression discharge chamber; the chamber body is connected to the pressurizing equipment and the circulating water pump. The function of the cooling chamber is to cool the product from high temperature to room temperature, and the product can be directly stored at room temperature or refrigerated after discharge.

[0026] Furthermore, the reduced pressure discharge chamber comprises a front discharge door and a rear discharge door, the rear discharge door at the rear end connects the outside with the reduced pressure discharge chamber, and a pressurizing device is arranged below the rear discharge door.

[0027] The reduced pressure feeding chamber and the reduced pressure discharging chamber adopt a reduced pressure ship lock design, which can complete the continuous discharging and feeding process when the whole system is under high pressure, thus ensuring the continuity of system operation.

[0028] Furthermore, the reduced pressure feeding chamber and the reduced pressure discharging chamber are in the shape of lying cylinders, and the front feeding door, the rear feeding door, the front discharging door and the rear discharging door are circular doors.

[0029] A microwave sterilization process based on a 433 MHz solid-state microwave source comprises the following steps:

[0030] (1) The decompression feeding chamber is depressurized through a valve, the front feeding door is opened, the material is placed on the loading rack, and the loading rack is fixed with a chain of the guide rail; the front feeding door is closed, and the decompression feeding chamber is pressurized by a pressurizing device; the rear feeding door is opened, the high-pressure cylinder is turned on, and the loading rack is pushed onto the guide rail of the preheating chamber;

[0031] (2) Set the preheating temperature of the preheating chamber to ≤50°C to preheat the material;

[0032] (3) Turn on the microwave source, set the sterilization temperature of the heating chamber and the incubator, and the material passes through each microwave processing module in turn and reaches the incubator for insulation treatment, achieving the sterilization target;

[0033] (4) The material enters the cooling chamber after passing through the insulation box and is quickly cooled to room temperature; the front door of the discharge is opened, and the loading rack enters the decompression discharge chamber, the decompression discharge chamber is depressurized through the valve, and the rear door of the discharge is opened to discharge the material; then the rear door of the discharge is closed, the decompression discharge chamber is pressurized, and the next round of discharge begins.

[0034] The beneficial effects of the present invention are:

[0035] (1) The microwave source of the present invention is a solid-state source. The solid-state source is highly controllable and has high frequency stability. It can provide real-time feedback and adjustment on the frequency, power (forward / reverse), phase, etc. during the operation of the equipment, thereby improving the uniformity of heating. It also occupies a small area and reduces the length of the waveguide. The frequency of the solid-state source is 433±15 MHz, and the microwave of this frequency corresponds to a wavelength of 669-717 mm. The microwave of this frequency has a greater penetration depth and can be used to process food of greater thickness. The height of the microwave heating cavity is less than 175 mm (approximately one quarter wavelength), and the width is less than 692 mm (approximately one wavelength), thereby achieving uniform heating.

[0036] (2) The decompression feeding chamber adopts a ship lock structure, which can complete the continuous discharging and feeding process when the system is under high pressure, ensuring the continuity of system operation. Traditional microwave sterilization can only process samples intermittently, for example, it must be heated to the preheating temperature of 90℃---heated to 120℃---cooled to room temperature 25℃, and the next batch of samples needs to be heated from 25℃ to 90℃. The processing of two batches of samples requires a complex heating and cooling process, which is not suitable for industrial production.

[0037] (3) Low preheating temperature. The water temperature of the preheating box is set to ≤50℃, which basically does not change the quality of food. The preheating temperature is lower than that of other patents.

[0038] (4) The microwave processing system is composed of multiple microwave processing modules (n≥1) connected together. The thermal type of each heating cavity is designed to be different. The temperature difference between hot and cold spots of the food to be sterilized can be minimized as much as possible by passing through multiple heating cavities. At the same time, different microwave window sizes are designed. Compared with a single microwave heating cavity, this multiple parallel connection method can improve the uniformity of heating and reduce the time of thermal sterilization.

[0039] (5) The width of the microwave heating cavity and the microwave window in each module are adjustable, and the uniformity can be improved by combining different sizes. The metal sheet on the loading rack can be adjusted for different foods to achieve the effect of adjusting the width of the heating cavity. The microwave distribution can also be changed by changing the size of the horn mouth to make the microwave heating more uniform.

[0040] (6) The preheating chamber, heating chamber, insulation box, and cooling chamber of the present invention all use independent water circulation systems, which do not require a heating and cooling process, making temperature control more precise, shortening processing time, and ensuring continuous operation of the system.

[0041] (7) The loading rack is provided with an electric field distribution regulator, which is made of metal and can adjust the electric field distribution in the microwave heating cavity to adjust the uniformity of microwave heating.

[0042] (8) The food carrier can carry n (n ≥ 1) rows of food at the same time, that is, it can carry n food in each horizontal direction. The microwave heating cavity design ensures that the microwave heating effect of the food in the same row is the same.

[0043] (9) The whole system can withstand a certain internal pressure (less than 3 atmospheres). The preheating chamber, heating chamber, insulation chamber, and cooling chamber are made of high temperature and pressure resistant metal materials with good airtightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0045] Figure 1 It is the overall structural diagram of the present invention.

[0046] Figure 2 It is a structural diagram of the microwave processing module.

[0047] Figure 3 is a top view of the microwave processing module.

[0048] Figure 4 It is a top view of the loading rack.

[0049] Figure 5 It is a schematic diagram of the structure of the reduced pressure feeding chamber and the preheating chamber.

[0050] Figure 6 It is a structural diagram of the thermal insulation box.

[0051] Figure 7 It is a schematic diagram of the structure of the cooling chamber and the pressure reducing discharge chamber.

[0052] Figure 8 It is a schematic diagram of the structure of a lying cylindrical decompression feeding chamber and a decompression discharging chamber.

[0053] Fig. 9 This is a simulation diagram of the electric field distribution in the XY direction.

[0054] Fig.10 This is a simulation diagram of the electric field distribution in the ZX direction.

[0055] Fig.11 This is a simulation diagram of the electric field distribution in the ZY direction.

[0056] In the figure, there are a reduced pressure feeding chamber 1, a feeding front door 11, a feeding rear door 12, a high-pressure cylinder 13, a preheating chamber 2, a preheating chamber sealing cover 21, a preheating chamber sealing ring 22, a microwave processing module 3, a heating cavity 31, a microwave source 32, a waveguide tube 33, a bell mouth 34, a microwave window 35, a loading rack 36, a metal sheet 37, an insulation box 4, an insulation box sealing cover 41, an insulation box sealing ring 42, a cooling chamber 5, a cooling chamber sealing cover 51, a cooling chamber sealing ring 52, a reduced pressure discharging chamber 6, a discharging front door 61, a discharging rear door 62, a circulating water pump 7, and a pressurizing device 8. Specific embodiments

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0058] Embodiment 1:

[0059] like Figure 1 As shown, a microwave sterilization system based on a 433MHz solid-state microwave source comprises a decompression feeding chamber 1, a preheating chamber 2, several groups of microwave processing modules 3, an insulation box 4, a cooling chamber 5 and a decompression discharging chamber 6 connected in sequence; the microwave processing system is composed of a plurality of microwave processing modules 3, and the thermal type of each heating chamber can be different by design, and the temperature difference between hot and cold spots of the food to be sterilized can be minimized by passing through a plurality of heating chambers; independent conveyor-type guide rails are arranged in the decompression feeding chamber 1, the preheating chamber 2, the microwave processing module 3, the insulation box 4, the cooling chamber 5 and the decompression discharging chamber 6, and are connected to respective motors, and the gap between the guide rails is smaller than the length of the material carrier, so that the material carrier can be transmitted between the guide rails, and further optimized so that the motor is connected to the control center and controlled by the control center, and can be opened uniformly or operated independently;

[0060] like Figure 2 and Figure 3 As shown, the microwave processing module 3 includes a heating cavity 31 with a guide rail inside, and the material is subjected to microwave sterilization in this cavity. A group of microwave heating components are respectively provided at the upper and lower ends of the heating cavity, and the microwave heating components include a microwave source 32 at the end, and the microwave source 32 is connected to the bell mouth 34 through a waveguide 33, and the lower end of the bell mouth is connected to the heating cavity 31 through a microwave window 35; the microwave source 32 is a 433MHz solid-state microwave source; the height of the heating cavity is less than 175mm (about a quarter wavelength), and the width is less than 692mm (about one wavelength), and heating in this near-field area can have better uniformity;

[0061] The preheating chamber 2, microwave treatment system 3, heat preservation box 4, and cooling chamber 5 are each equipped with a circulating water pump 7. The chambers are all filled with soft water, and the upper part is air. The doors connecting the chambers are opened above the water level; each part is equipped with an independent water circulation system to control the temperature. Between each chamber, a servo motor is used to lift the material rack out of the water, and the servo motor is used to put the material rack on the guide rail, and then a compressed air cylinder is used to push the material rack to the rear box; this completes the transition between the two boxes.

[0062] like Figure 4 As shown, there are movable metal sheets 37 on the left and right sides of the material carrier 36. The metal sheets are at the same height as the microwave heating cavity and play a role in regulating the electric field.

[0063] The microwave windows in each microwave processing module are designed to be of different sizes. The spacing between the metal sheets can be adjusted for different foods to change the actual heating width of the heating cavity, thereby achieving the effect of adjusting the width of the heating cavity and making microwave heating more uniform.

[0064] like Figure 5 As shown, the decompression feeding chamber 1 includes a feeding front door 11 and a feeding rear door 12. The front feeding front door 11 at the front end connects the outside with the decompression feeding chamber, and a high-pressure cylinder 13 is arranged below it. The chamber body is connected to a pressurizing device 8, such as but not limited to a pressurizing cylinder, and the rear feeding rear door 12 at the rear end connects the decompression feeding chamber with the preheating chamber 2. The ship lock design can complete the continuous feeding process when the whole system is under high pressure, thereby ensuring the continuity of the system operation.

[0065] The front end of the preheating chamber 2 is a feeding rear door 12, the top is a preheating chamber sealing cover 21, and a preheating chamber sealing ring 22 is provided at the connection with the chamber body. The chamber body is connected to the pressurizing device 8 and the circulating water pump 7; the rear end is connected to the heating cavity of the microwave processing module 3 at the front end through a pipeline; the design of the preheating chamber can reduce the temperature difference of microwave heating and reduce the unevenness of microwave heating. At the same time, the preheating temperature of this patent is less than or equal to 50°C, which basically does not change the quality of food.

[0066] like Figure 6 As shown, the front end of the heat preservation box 4 is connected to the heating cavity of the microwave processing module 3 at the end through a pipeline, the top is a heat preservation box sealing cover 41, and a heat preservation box sealing ring 42 is provided at the connection with the box body, the rear end is connected to the front end of the cooling chamber 5 through a pipeline, and the bottom is connected to the circulating water pump 7. By using traditional thermal sterilization, the microwave cold point reaches the required temperature for the sterilization effect, and microwave sterilization and thermal sterilization are used together to reduce the time of thermal sterilization, and improve the food quality while meeting the sterilization requirements.

[0067] like Figure 7As shown, the front end of the cooling chamber 5 is connected to the rear end of the heat preservation box through a pipeline, the top is a cooling chamber sealing cover 51, and a cooling chamber sealing ring 52 is provided at the connection with the chamber body, and the rear end is connected to the decompression discharge chamber 6 through the discharge front door 61 of the decompression discharge chamber; the chamber body is connected to the pressurizing device 8 and the circulating water pump 7. The function of the cooling chamber is to cool the product from high temperature to room temperature, and the product can be directly stored at room temperature or refrigerated after discharge.

[0068] The decompression discharge chamber 6 comprises a discharge front door 61 and a discharge rear door 62. The discharge rear door 62 at the rear end is connected with the outside and the decompression discharge chamber, and a pressurizing device 8 is arranged below the discharge rear door 62.

[0069] The reduced pressure feeding chamber and the reduced pressure discharging chamber adopt a reduced pressure ship lock design, which can complete the continuous discharging and feeding process when the whole system is under high pressure, thus ensuring the continuity of system operation.

[0070] Embodiment 2:

[0071] like Figure 8 As shown, the decompression feeding chamber 1 and the decompression discharging chamber 6 are in the shape of lying cylinders, and the feeding front door 11, the feeding rear door 12, the discharging front door 61 and the discharging rear door 62 are circular doors. The cylindrical box has better pressure resistance.

[0072] A microwave sterilization process based on a 433 MHz solid-state microwave source comprises the following steps:

[0073] (1) The decompression feeding chamber is depressurized through a valve, the front feeding door is opened, the material is placed on the loading rack, and the loading rack is fixed with a chain of the guide rail; the front feeding door is closed, and the decompression feeding chamber is pressurized by a pressurizing device; the rear feeding door is opened, the high-pressure cylinder is turned on, and the loading rack is pushed onto the guide rail of the preheating chamber;

[0074] (2) Set the preheating temperature of the preheating chamber to ≤50°C to preheat the material;

[0075] (3) Turn on the microwave source, set the sterilization temperature of the heating chamber and the incubator, and the material passes through each microwave processing module in turn and reaches the incubator for insulation treatment, achieving the sterilization target;

[0076] (4) The material enters the cooling chamber after passing through the insulation box and is quickly cooled to room temperature; the front door of the discharge is opened, and the loading rack enters the decompression discharge chamber, the decompression discharge chamber is depressurized through the valve, and the rear door of the discharge is opened to discharge the material; then the rear door of the discharge is closed, the decompression discharge chamber is pressurized, and the next round of discharge begins.

[0077] The whole system of the present invention can withstand a certain internal pressure (less than 3 atmospheres). The preheating chamber, heating chamber, heat preservation chamber and cooling chamber are made of high temperature and pressure resistant metal materials with good airtightness.

[0078] like Figure 9-11 As shown, XYZ represent the length, width and height of the heating chamber respectively.

[0079] From the electric field simulation diagram in the XY direction, it can be seen that the distribution of the electromagnetic field is concentrated in the central area of ​​the heating cavity, which can effectively avoid the edge heating phenomenon. There is no obvious cold spot area, the distribution is relatively uniform, and the energy is concentrated in the center of the heating cavity.

[0080] From the simulation diagram of the electric field distribution in the ZX direction, it can be seen that in the X direction, the electric field distribution in the vertical direction (Z direction) is in a symmetrical state, the electromagnetic field is concentrated in the middle of the heating cavity, and the electric field intensity in the middle of the heating cavity is large. The energy distribution is concentrated in the center.

[0081] From the electric field distribution simulation diagram in the ZY direction, it can be seen that in the Y direction, the electric field is symmetrically distributed with respect to the Y axis, the electromagnetic field is concentrated in the middle of the heating cavity, and the electric field intensity in the middle of the heating cavity is large. The energy distribution in the center of the heating cavity is the strongest.

[0082] In short, the electric field distribution in the three directions is symmetrical, which ensures the symmetry and concentration of energy distribution and maximizes the efficiency of energy conversion.

Claims

1. A process for a microwave sterilization system based on a 433MHz solid-state microwave source, characterized in that The following microwave sterilization system is adopted: it includes a reduced pressure feeding chamber, a preheating chamber, several groups of microwave processing modules, an insulation box, a cooling chamber and a reduced pressure discharging chamber connected in sequence; the reduced pressure feeding chamber, the preheating chamber, the microwave processing module, the insulation box, the cooling chamber and the reduced pressure discharging chamber are all provided with independent guide rails connected to their respective motors; the microwave processing module includes a heating cavity, and a group of microwave heating components are respectively provided at the upper and lower ends of the heating cavity, and the microwave heating components include a microwave source at the end, the microwave source is connected to the bell mouth through a waveguide, and the lower end of the bell mouth is connected to the heating cavity through a microwave window; the heat type of each heating cavity is different; the microwave source is a 433MHz solid-state microwave source; the preheating chamber, the microwave processing system The system, the insulation box and the cooling chamber are each provided with a circulating water pump, and the chambers are all filled with soft water; the left and right sides of the loading rack are movable metal sheets, and the metal sheets are at the same height as the microwave heating chamber; the decompression feeding chamber and the decompression discharging chamber adopt a decompression ship lock design; the decompression feeding chamber includes a feeding front door and a feeding rear door, the front feeding front door is connected to the outside world and the decompression feeding chamber, and a high-pressure cylinder is arranged below it, the chamber body is connected to the pressurizing equipment, and the rear feeding rear door is connected to the decompression feeding chamber and the preheating chamber; the decompression discharging chamber includes a discharging front door and a discharging rear door, the rear discharging rear door is connected to the outside world and the decompression discharging chamber, and a pressurizing equipment is arranged below it; the height of the heating chamber is less than 175mm, and the width is less than 692mm; The following steps are involved: (1) Adjust the spacing of the metal sheets according to different foods to change the actual heating width of the heating chamber; (2) The decompression feeding chamber is depressurized through a valve, the front feeding door is opened, the material is placed on the loading rack, and the loading rack is fixed with a chain of the guide rail; the front feeding door is closed, and the decompression feeding chamber is pressurized by a pressurizing device; the rear feeding door is opened, the high-pressure cylinder is opened, and the loading rack is pushed onto the guide rail of the preheating chamber; (3) Set the preheating temperature of the preheating chamber to ≤50°C to preheat the material; (4) Turn on the microwave source, set the sterilization temperature of the heating chamber and the incubator, and the material passes through each microwave processing module in turn and reaches the incubator for insulation treatment to achieve the sterilization goal; (5) After passing through the insulation box, the material enters the cooling chamber and is quickly cooled to room temperature; the front door of the discharge is opened, and the loading rack enters the decompression discharge chamber, the decompression discharge chamber is depressurized through the valve, and the rear door of the discharge is opened to discharge the material; then the rear door of the discharge is closed, the decompression discharge chamber is pressurized, and the next round of discharge begins.

2. The process according to claim 1, characterized in that: The front end of the preheating chamber is the feeding rear door, the top is the preheating chamber sealing cover, and a preheating chamber sealing ring is provided at the connection with the chamber body. The chamber body is connected to the pressurizing equipment and the circulating water pump; the rear end is connected to the heating cavity of the microwave processing module at the front end through a pipeline.

3. The process according to claim 1, characterized in that: The front end of the insulation box is connected to the heating cavity of the microwave processing module at the end through a pipe. The top is the insulation box sealing cover, and a insulation box sealing ring is provided at the connection with the box body. The rear end is connected to the front end of the cooling chamber through a pipe, and the bottom is connected to the circulating water pump.

4. The process according to claim 1, characterized in that: The front end of the cooling chamber is connected to the rear end of the insulation box through a pipeline. The top is a cooling chamber sealing cover, and a cooling chamber sealing ring is provided at the connection with the chamber body. The rear end is connected to the decompression discharge chamber through the discharge front door of the decompression discharge chamber; the chamber body is connected to the pressurizing equipment and the circulating water pump.

5. The process according to claim 1, characterized in that: The reduced pressure feeding chamber and the reduced pressure discharging chamber are in the shape of lying cylinders, and the front feeding door, the rear feeding door, the front discharging door and the rear discharging door are circular doors.

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