CN106658803B - Heating device capable of adjusting microwave energy distribution - Google Patents

Abstract

The invention relates to the technical field of food processing, and discloses a heating device capable of adjusting microwave energy distribution. The device comprises a microwave generator and a waveguide system, wherein the microwave generator is connected with the waveguide system, microwaves are transmitted to a microwave heating cavity through the waveguide system, a horn mouth of the waveguide system is communicated with a box-type oscillating cavity through a first flange, the box-type oscillating cavity is communicated with the microwave heating cavity through a second flange, an communicating part is sealed by engineering plastics, microwaves diffused through the horn mouth form a stable set microwave mode in the box-type oscillating cavity, and the height of the box-type oscillating cavity is not less than half wavelength of the set microwaves. According to the invention, the microwave regulator is arranged in the waveguide system, so that the energy distribution in the microwave heating cavity is changed, and different parts of food are heated in a targeted manner.

Description

A heating device with adjustable microwave energy distribution

technical field

The invention belongs to the new technology field of food processing, and in particular relates to a heating device capable of adjusting microwave energy distribution.

Background technique

Microwave refers to electromagnetic waves with a frequency range between 300MHz and 300GHz. Microwave has been widely used in modern radar and communication technology. In addition to being used in communications, the heating properties of microwaves on dielectric materials make them a new technology for food thermal processing. The traditional thermal processing method is to heat the packaged food in hot water or steam at 121.1°C for 60-90 minutes in a high-temperature sterilizer to inactivate spoilage pathogenic bacteria and ensure the safety of the food. safety. During the heat treatment process, along with the inactivation of pathogenic bacteria, the nutritional and sensory qualities of food are reduced due to heat. In theory, increasing the sterilization temperature and reducing the heating time can improve the quality of food while ensuring the lethality of microorganisms. However, the traditional hot water or steam heating methods use the temperature difference from the outside to the inside as the power to transfer heat, which is limited. Due to the low heat transfer coefficient of food, this method heats unevenly and takes a long time. Therefore, it is difficult for traditional thermal processing methods to greatly improve food quality while ensuring food safety. With the acceleration of the pace of modern life, traditional processed food can no longer meet people's demand for high-quality and convenient food. Therefore, various new science and technology are tried to be applied to the food field to produce safe, high-quality and long-term products. Among them, microwave heating technology is regarded as the most promising heating technology for industrialization.

Although microwave heating technology has been widely used in household microwave ovens, it has not been promoted so far due to limitations in technology and equipment in industrial sterilization. There are still many technical difficulties in the industrial application of microwave sterilization technology, such as uneven heating and unfixed cold spot position.

Contents of the invention

The invention provides a heating device capable of adjusting microwave energy distribution, which solves the problem of uneven microwave heating.

The present invention can be realized through the following technical solutions:

A heating device with adjustable microwave energy distribution, including a microwave generator and a waveguide system, the microwave generator is connected to the waveguide system, and the microwave is transmitted to the microwave heating cavity through the waveguide system, and the bell mouth of the waveguide system passes through the first method The flange communicates with the box-type oscillation cavity, which is connected to the microwave heating cavity through the second flange, and the connecting part is sealed with engineering plastics, and the microwave diffused by the bell mouth forms a stable microwave in the box-type oscillation cavity. A microwave mode is set, and the height of the box-type oscillating cavity is not less than half the wavelength of the set microwave.

Further, a box-type oscillation cavity is connected above and below the microwave heating cavity, and then the waveguide system and the microwave generator are connected through the box-type oscillation cavity.

Further, a microwave regulator is arranged inside the box-type oscillation cavity, and the microwave regulator adjusts the regional distribution of the heating degree in the microwave heating cavity by adjusting the distribution of microwave energy.

Further, the microwave regulator is arranged above the corresponding area in the microwave heating chamber where heating intensity needs to be enhanced.

Further, the microwave regulator is detachably fixed in the box-type oscillating cavity near the interface of the microwave heating cavity.

Further, the microwave regulator is made of metal or engineering plastics.

Further, the microwave regulator is set in different sizes and shapes according to different foods to be heated, so as to adjust the distribution of microwave energy, centrally heat the foods to be heated, and promote heating uniformity.

Further, the microwave regulator adopts a metal round tube or a square plastic rod.

The beneficial technical effects of the present invention are:

By arranging a box-type oscillating cavity behind the bell mouth of the waveguide system and a microwave regulator in the box-type oscillating cavity, the energy distribution inside the microwave heating cavity is changed, so that different parts of the food are heated in a targeted manner.

Description of drawings

Fig. 1 is a block diagram of the overall structure of the present invention;

Fig. 2 is a schematic diagram of the structure of the heating cavity of the present invention;

Fig. 3 is a schematic structural view of the food loading device of the present invention;

Fig. 4 is a schematic diagram of the three-dimensional structure of the microwave heating chamber of the present invention;

Fig. 5 is a schematic side view of a microwave heating chamber of the present invention;

Fig. 6 is a three-dimensional structural schematic diagram of the bell mouth and the oscillation chamber of the present invention;

Among them, 1-preheating chamber, 2-microwave heating chamber, 3-constant temperature sterilization chamber, 4-cooling chamber, 5-first water outlet, 6-first water inlet, 7-second water outlet, 8-second Water inlet, 9-third water outlet, 10-third water inlet, 11-first water pump, 12-first heat exchanger, 13-second water pump, 14-second heat exchanger, 15-third water pump , 16-the third heat exchanger, 17-food carrier, 18-servo motor lifting flat push device, 19-horizontal chain device, 20-first vertical chain device, 21-second vertical chain device, 22-axon, 23-metal shielding plate, 24-chain, 25-horn mouth, 26-cassette oscillator, 27-microwave regulator, 28-waveguide system.

Detailed ways

The specific implementation manner of the present invention will be described in detail below in conjunction with the accompanying drawings and preferred embodiments.

As shown in Fig. 1, the overall structure schematic diagram of the present invention. An intelligent microwave heating device, including a microwave generator, a waveguide system, a heating cavity, a food loading device and an intelligent microwave system. Packaged food is rapidly heated and sterilized. The frequency of the microwave source is between 890-940MHz and 2400-2500MHz, and the frequency fluctuation is less than 2MHz.

As shown in FIG. 2 , the heating chamber is divided into four parts: a preheating chamber 1 , multiple microwave heating chambers 2 , a constant temperature sterilization chamber 3 and a cooling chamber 4 . The whole cavity is made of stainless steel. These four parts are filled with water of different temperatures, and the packaged food passes through these four parts sequentially in the water through the food loading device. These four parts have independent water circulation systems, and the water temperature of each part can be set according to needs. Each part is equipped with a temperature monitoring point, and the external heat exchanger is equipped to adjust the water temperature in real time, and the internal pressure of the system can be set according to the water temperature, from 0 to 0.3MPa.

The preheating chamber and the first microwave heating chamber are separated by the first partition, and the constant temperature sterilization chamber and the cooling chamber are separated by the second partition. The first partition and the second partition are fixed at the bottom of the cavity and are connected with the cavity. The tops are not in contact, and each microwave heating chamber communicates with the constant temperature sterilization chamber.

The preheating water inlet 5 is set at the lower part of the preheating chamber, and the preheating water outlet 6 is set at the upper part, and the preheating water inlet 5 and the preheating water outlet 6 are connected through the preheating water pump 11 and the preheating heat exchanger 12, and the water circulation system Use the preheating water pump 11 and the preheating heat exchanger 12 to complete the circulation of water in the preheating chamber and keep the water temperature stable; set the heating water inlet 7 at the bottom of the first microwave heating chamber, and set the heating water outlet 8 at the top of the constant temperature sterilization chamber. Between the heating water inlet 7 and the heating water outlet 8, the heating water pump 13 is connected to the heating heat exchanger 14, and the water circulation system utilizes the heating water pump 13 and the heating heat exchanger 14 to complete the circulation of water in the microwave heating chamber and the constant temperature sterilization chamber. Keep the water temperature stable; a cooling water inlet 9 is set at the lower part of the cooling chamber, and a cooling water outlet 10 is set at the upper part, and the cooling water pump 15 and the cooling heat exchanger 16 are connected between the cooling water inlet 9 and the cooling water outlet 10. 15 and the cooling heat exchanger 16 complete the circulation of water in the cooling cavity and keep the water temperature stable.

The preheating chamber uses a preheating heat exchanger to heat the water in it until it reaches the preheating temperature (generally 30-60 degrees), then puts the food in for preheating, and stands for a period of time (generally 15-40 minutes ) so that each part has a uniform initial temperature.

There are two symmetrical heating windows on the upper and lower sides of the microwave heating cavity. The microwave is transmitted from the microwave generator to the microwave heating cavity through the waveguide system 28. First, the microwave is divided into two parts by the horizontal power divider, and then each part is divided by the vertical power The distributor is divided into upper and lower parts, which enter the microwave heating cavity through the heating window of the microwave heating cavity from the upper and lower parts respectively. The heating window is sealed by engineering plastics to prevent the moisture in the microwave heating cavity from flowing out while the microwave enters. The food is heated by microwaves, and the temperature quickly rises to the target sterilization temperature (90 degrees to 125 degrees). The setting of each microwave heating cavity requires that the inner wall is smooth, the cavity window material is high pressure resistant, and the window size is adjustable.

Constant temperature sterilization chamber: After the food is heated by microwaves, it is kept in water at the temperature of heat sterilization for a certain period of time (generally 3-15 minutes) to achieve the expected sterilization effect, that is, the lethality of microorganisms.

The cooling chamber uses a cooling heat exchanger to heat the water in it until it reaches the cooling temperature (0-25 degrees), and quickly cools the food that has reached the sterilization effect in the cooling chamber, usually for 5-10 minutes.

The invention aims at industrialized production, and the food flow of the whole device is realized through the food loading device. The device adopts a non-conveyor belt design, and uses a specially designed food carrier to complete the heating process for N foods at a time, which can realize continuous operation. As shown in Figure 3, the food loading device includes a food carrier 17, a servo motor lifting and pushing device 18 arranged in the preheating chamber 1, a horizontal chain device 19 arranged in the microwave heating chamber 2, and a sterilizing device arranged in the constant temperature sterilization chamber 3. The movement directions of the chain device 20 and the cooling chain device 21 arranged in the cooling chamber 4, and the sterilization chain device 20 and the cooling chain device 21 are opposite.

As shown in FIG. 4 and FIG. 5 , in order to eliminate the influence of chains on microwave distribution, metal shielding plates 23 are provided along the length direction on both sides of each microwave heating chamber 2 . The metal shielding plate 23 is movably fixed on the bottom of the microwave heating cavity 2, not higher than the top of the microwave heating cavity. The chain of the horizontal chain device is arranged between the cavity on both sides of the microwave heating cavity and the metal shielding plate 23, and a plurality of axons 22 are arranged on both sides of the food carrier 17, and the food carrier is connected to the chain 24 through the axons 22, and the chain is provided with A plurality of notches, the axons pass through the notches above the metal shielding plate 23 and on the chain to detachably fix the food carrier.

Food flow is as follows in the whole device of the present invention:

Preheating chamber: firstly, put the food to be heated into the food carrier, then stack the food carriers one by one, put them into the preheating chamber for preheating; when the preheating time is up, the servo motor lifts the horizontal pushing device to Multiple food carriers stacked together are lifted, and then the long cylinder in the device is used to push the food carriers one by one through the first partition and enter the first microwave heating cavity, and put them on the horizontal chain device in the microwave heating cavity ;

Microwave heating chamber: The notch on the chain of the horizontal chain device is fixed with the axon of the food carrier, so that the chain drives the food carrier to move inside the cavity, and the general running speed is 2-10m/min; when the heating is completed, Driven by the chain, the food carrier reaches the junction of the last microwave heating chamber and the constant temperature sterilization chamber. At this time, the long cylinder of the horizontal chain device is used to push the food carrier to the sterilization chain device of the constant temperature sterilization chamber;

Constant temperature sterilization chamber: the food carrier falls on the chain of the sterilization chain device. Driven by the chain, it moves slowly inside the chamber; when the sterilization is completed, the food carrier moves to the junction of the constant temperature sterilization chamber and the cooling chamber. At this time, the food The carrier breaks away from the chain and falls on the lower plate, and the food carrier is lifted to the top of the second partition by using the cylinder installed under the plate in the sterilizing chain device, and then another cylinder is used to push the food carrier across the second partition to enter On the cooling chain device of the cooling chamber;

Cooling chamber: The food carrier falls on the chain of the cooling chain device. Driven by the chain, it moves slowly inside the chamber until it is cooled and moved out of the chamber, and finally the food is heated.

The operation of the whole system is controlled by the intelligent microwave system: including the power setting during operation, the moving speed of food, the opening and closing of valves, and the real-time monitoring of the temperature of each part. The continuity of the main controller MCU is monitored by the fault diagnosis module. The main controller MCU is connected with the microwave generator for controlling microwave power; the main controller MCU is connected with the preheating water pump, heating water pump and cooling water pump respectively for controlling the preheating chamber, multiple microwave heating chambers, constant temperature sterilization Water velocity in the chamber and cooling chamber;

The main controller MCU is connected to the preheating heat exchanger, the heating heat exchanger and the cooling heat exchanger respectively, and is used to control the water temperature of the preheating chamber, multiple microwave heating chambers, constant temperature sterilization chamber and cooling chamber;

The main controller MCU is connected with the servo motor of the servo motor lifting and pushing device, which is used to lift multiple food carriers stacked together one by one across the top of the first partition and push them into the horizontal chain device of the microwave heating chamber ; The main controller MCU is connected with the servo motor of the horizontal chain device, and is used to push the food carriers one by one into the sterilization chain device of the constant temperature sterilization chamber; the main controller MCU is connected with the servo motor of the sterilization chain device, and is used to push The food carriers are lifted one by one across the top of the second partition and pushed flatly into the cooling chain device of the cooling cavity. The main controller MCU is connected with the servo motor of the cooling chain device, and is used to move the food carriers out of the cooling cavity one by one.

The main controller MCU controls the water temperature to maintain the preheating temperature according to the feedback of the preheating temperature sensor set in the preheating chamber; the main controller MCU controls the water temperature to maintain the heating and sterilization temperature according to the feedback of the heating temperature sensor set in the constant temperature sterilization chamber ; The main controller MCU controls the water temperature to maintain the cooling temperature according to the feedback from the cooling temperature sensor arranged in the cooling cavity.

The main controller MCU controls the preheating time according to the feedback of the timer set in the preheating chamber;

The water flow velocity in the preheating chamber, the constant temperature sterilization chamber and one or more microwave heating chambers and cooling chambers is uniform; the moving speed of the food carrier in one or more microwave heating chambers, constant temperature sterilization chambers and cooling chambers is also uniform And set different moving speeds according to different foods.

The traditional bell mouth design is to disperse microwaves and guide them into the microwave heating cavity, and the bell mouth 25 is connected to the microwave heating cavity 2 through a flange. The design of the present invention is bell mouth-cassette vibration cavity, as shown in Figure 6, the bell mouth 25 communicates with the cassette vibration cavity 26 through the first flange, and the cassette vibration cavity 26 passes the second flange and the microwave heating cavity 2. Communication, the connection part is sealed with engineering plastics, and the microwave diffused by the bell mouth forms a stable design microwave mode in the box-type oscillation cavity 26, such as TE10, TE20, TE30, etc. The height of the box-type oscillation chamber 26 is not less than the half wavelength of the set microwave, the width is less than the distance between the metal shielding plates 23 in the microwave heating chamber 2, and the length is not greater than the length of the metal shielding plates 23 in the microwave heating chamber 2.

A microwave regulator 27 is arranged in the box-type oscillating chamber 26 , which regulates the microwave energy distribution inside the microwave heating chamber. It can be known from experiments that the material can be metal or engineering plastic, and the metal or plastic regulator can make the microwave energy be gathered directly under the regulator, thereby adjusting the energy distribution of the microwave. Due to the difference in size and thickness of the food itself, it will cause uneven heating inside the food during microwave heating. Therefore, microwave regulators of different sizes and shapes can be set according to different foods to adjust the distribution of microwave energy, such as metal round tubes and plastic round tubes. Or square plastic rods, etc., can increase the heating degree of the low temperature area, promote heating uniformity, thereby improving the quality of food heating.

The diameter range of the metal round tube is 5-100mm, the width range of the square plastic rod is 10-50mm, and the thickness range is 10-100mm.

The invention realizes the circulating flow of water in the cavity through the unique design of the heating cavity combined with the water pump and the heat exchanger, thereby improving the quality of food heating; with the help of the food loading device and the intelligent control system, the industrial application of microwave heating is realized; through the waveguide A box-type oscillating cavity is set behind the bell mouth of the system and a microwave regulator is set in the box-type oscillating cavity, which changes the energy distribution inside the microwave heating cavity, thereby heating different parts of the food in a targeted manner.

Although the specific implementations of the present invention have been described above, those skilled in the art should understand that these are only examples, and various changes or changes can be made to these implementations without departing from the principle and essence of the present invention. Modifications, therefore, the scope of protection of the invention is defined by the appended claims.

Claims (3)

1. A heating device capable of adjusting microwave energy distribution, comprising a microwave generator and a waveguide system, the microwave generator is connected to the waveguide system, and microwaves are transmitted to the microwave heating cavity through the waveguide system, characterized in that: the waveguide system The bell mouth communicates with the box-type oscillating cavity through the first flange, and the box-type oscillating cavity communicates with the microwave heating cavity through the second flange. A stable set microwave mode is formed in the oscillating cavity, and the height of the box-type oscillating cavity is not less than half the wavelength of the set microwave; A microwave regulator is arranged inside the box-type oscillating cavity, and the microwave regulator adjusts the regional distribution of the heating degree in the microwave heating cavity by adjusting the distribution of microwave energy; The microwave regulator is arranged above the area corresponding to the area where the heating intensity needs to be enhanced in the microwave heating chamber; the microwave regulator is made of metal or engineering plastic material; the microwave regulator is set to different sizes and sizes according to different foods to be heated. Different shapes, so as to adjust the distribution of microwave energy, centrally heat the food to be heated, and promote heating uniformity; The microwave regulator adopts a metal round tube or a square plastic rod; the diameter of the metal round tube is 5-100 mm, the width of the square plastic rod is 10-50 mm, and the thickness is 10-100 mm. 2. The heating device with adjustable microwave energy distribution according to claim 1, characterized in that: the microwave heating cavity is respectively connected with a box-type oscillation cavity above and below, and then the waveguide system and the microwave generator are connected through the box-type oscillation cavity device. 3 . The heating device with adjustable microwave energy distribution according to claim 1 , wherein the microwave regulator is detachably fixed in the box-type oscillating cavity near the interface of the microwave heating cavity. 4 .

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