RU2807532C1 - Microwave milk pasteurizer - Google Patents

Abstract

FIELD: dairy industry.

SUBSTANCE: invention relates to equipment for milk pasteurization. A microwave milk pasteurizer contains connected sections of dual quasi-stationary toroidal resonators, joined by bases, each resonator is presented in the form of a torus of rectangular cross-section and a capacitor part formed by a parallel resonator base and a small base, with holes provided in them, located evenly around the circumferences so that the distance between holes of more than a quarter wavelength, through which radio-transparent milk pipes with a cross-section of less than two wave penetration depths are laid in the capacitor parts of the resonators of all sections, while waveguides with magnetrons are installed on the side surfaces of each resonator along the perimeter of the bases with a shift of 120 degrees, the emitters of which are directed to the capacitor parts through corresponding ceramic cylindrical mirrors located coaxially on the internal surfaces of the resonators, and in the open spaces of the outer resonators there are slowing non-ferromagnetic spiral devices through which radio-transparent milk pipelines are laid.

EFFECT: invention makes it possible to reduce the bacterial contamination of milk and thereby preserve its biological value.

1 cl, 7 dwg

Description

The invention relates to equipment for thermal processing of food products, in particular for pasteurization of milk.

Milk is pasteurized to destroy pathogenic microflora, reduce overall bacterial contamination, obtain desired organoleptic properties, viscosity, curd density, etc. Pasteurization involves purifying milk from pathogenic microorganisms (tuberculosis and brucellosis bacteria) at a temperature slightly lower than the boiling point. The basic properties of milk (consistency, taste, smell) remain virtually unchanged.

There are three ways to pasteurize milk [1]:

- the first method is long-term pasteurization, milk is heated to a temperature of 63-65°C and pasteurized for 30 minutes;

- the second method is short-term pasteurization, the milk is heated to a temperature of 72-75 ° C and pasteurized for 30-40 s;

- the third method is flash pasteurization, the milk is heated to a temperature of 85-90 ° C and pasteurized for 8-10 s. At this temperature, the taste and aroma of milk, physicochemical properties (gases evaporate, acidity decreases by 0.5-1°T), and the salt composition of casein change. Albumin protein is denatured already at 60-65°C. If the access of oxygen to the pasteurizer is limited, then vitamins are resistant to heat treatment [1].

The priority areas for improving and creating new pasteurization and cooling units are to reduce the energy intensity of heat exchange processes and minimize their geometric dimensions.

There are various designs of pasteurization and cooling units: capacitive (long-term pasteurization); plate (short-term pasteurization); tubular (flash pasteurization) [2].

1. Heating of milk in long-term pasteurization baths is carried out by hot water heated by steam directly in the jacket, and cooling by ice water distilled through the jacket. The steam consumption for pasteurization of 1000 kg of milk is 100-140 kg, which is 4.5-5 times more than in plate pasteurizers.

2. The plate heat exchanger has three sections: pasteurization, recovery and cooling. The hot product leaving the recovery section in the flow transfers heat to the incoming cold product. The hot product is partially cooled before entering the cooling section. The heating and cooling processes are carried out in a closed flow. Raw milk from the storage tank is pumped into the intermediate tank, from there it is pumped through the flow stabilizer to the regeneration section, where it is heated with pasteurized milk. Then the milk is fed under pressure into the pasteurization section, where it is heated with hot water to a temperature of 76-78°C and sent to a tubular soaker, and then to the regeneration section. [12]

Advantages of a plate pasteurizer: small overall dimensions (three times smaller than a tubular pasteurizer with equal productivity); ability to work with minimal thermal pressure; specific steam consumption is 2-3 times less than in tubular pasteurizers, and 4-5 times less than in capacitive heat exchangers.

3. Tubular pasteurizers are designed for processing milk in a stream at high speeds. There are one-, two- and four-section pasteurizers. A single-section steam-heated apparatus consists of a cylindrical body with thermal insulation and a closed steel casing. Inside the housing there is a tubular heat exchanger consisting of pipes connected in pairs and covers with rubber seals. They isolate the channels from each other, creating a coil. The first and last pipes of the heat exchanger are led out of the cylinder in the form of branch pipes with fittings for inlet and outlet of the processed milk. To automatically remove condensate from the annulus there is a condensate drain. The milk enters the heat exchanger through the pipe, passing through coil channels, and is heated by steam to a predetermined temperature. A temperature sensor with a temperature controller is installed at the milk outlet from the heat exchanger. Disadvantages: high metal consumption; large overall dimensions compared to a plate pasteurizer with equal productivity; lack of heat recovery section; inconvenience for sanitary processing [1,2].

4. The pasteurization-cooling unit UOM-IK is known, where in addition to the plate heat exchanger and dryer there is an infrared heating section. It consists of an anodized aluminum reflector and 16 quartz U-tubes, on which a nichrome spiral is wound. The tubes are connected to the network in parallel. The plate heat exchanger has a regeneration section and two cooling sections. Milk from the surge tank is sequentially supplied by pump to the regeneration, infrared heating and holding sections. After aging, pasteurized milk passes through a regeneration section, transferring heat to cold milk, and successively passes through cooling sections with water and brine. Advantages: small working capacity (three times less than a tubular pasteurizer with equal productivity) [2].

5. Milk pasteurizers with a capacity of 1000 l/h are known, the operation of which is based on the use of ultraviolet radiation. Its body contains a milk dispenser, gas-discharge lamps with pasteurization plates and a power supply. The milk is fed through the sprinkler valves in a thin layer onto the upper pasteurization plate, where it passes through an intense stream of UV rays. Then it flows to the lower plate, where it is re-irradiated by the lower irradiator. The power supply unit contains ballasts that ensure the operation of the irradiators [2].

It is also known that milk is disinfected with ultraviolet and infrared rays in a continuous flow at a layer thickness of 3-5 cm at a speed of 4-5 cm/s, with sequential irradiation for 20-50 minutes. [2].

A known installation contains a cavity resonator of a microwave generator, inside of which there is a radio-transparent sectioned drum in a cylindrical radio-transparent housing with a lid [3].

A microwave installation for pasteurization of mastitis milk is known [4], which contains horizontally arranged and connected sections, each of which is a cylindrical resonator connected in series with a flange and a cylindrical shell-and-tube heat exchanger with water inlet and outlet pipes. A cylindrical fluoroplastic distributor is coaxially installed inside the cylindrical resonator so that its cylindrical channels are connected to the heat exchanger tubes, the bases of which serve as the bases of the cylindrical resonator. The diameter of the cylindrical channels does not exceed two depths of penetration of the ultrahigh frequency electromagnetic field into mastitis milk. Magnetrons are installed on the side of each cylindrical resonator. The invention provides an increase in the biological value of mastitis milk.

Quasi-stationary toroidal resonators are known, the operating principle of which is based on the interaction of an electromagnetic oscillation with an electron flow. Their feature is a pronounced spatial separation of the electric and magnetic fields, which allows us to consider such resonators as connected lumped capacitances and inductances [5, p. 369].

Spiral decelerating systems are known [6, p. 18], an important feature of which is that the intensity of the electric field drops sharply with distance from the surface of the spiral, so the electric field strength is low. A non-ferromagnetic spiral inside a non-ferromagnetic cylinder for the centimeter wave range performs the function of a transient waveguide. If the diameter of a non-ferromagnetic wire is small compared to the diameter of the spiral, then it can be considered as an anisotropic cylinder, the conductivity of which is infinite in the direction of the spiral turns and equal to zero in the perpendicular direction [7, pp. 98-99]. This principle is incorporated in the designed multi-section microwave pasteurizer to ensure electromagnetic safety during continuous pumping of milk through quasi-stationary toroidal resonators.

The scientific and technical task is to develop a system that provides effective heat exchange processes to suppress the vital activity of vegetative forms of microorganisms in milk by exposure to a high-intensity electric field in the centimeter range (frequency 2450 MHz, wavelength 12.24 cm, wave penetration depth into milk 1.0-1.5 cm).

The purpose of this work is to develop a continuous-flow microwave milk pasteurizer that provides disinfection by exciting a high-intensity electric field in a quasi-stationary resonator.

The technical objective of the invention is to preserve the biological value of milk by reducing its bacterial contamination.

The technical result is achieved by the fact that the microwave milk pasteurizer contains connected sections of dual quasi-stationary toroidal resonators, joined by bases,

Moreover, each resonator is presented in the form of a torus of rectangular cross-section and a capacitor part formed by a parallel base of the resonator and a small base, with holes provided in them, with a diameter of less than a quarter of the wavelength, located evenly around the circles so that the distance between the holes is more than a quarter of the wavelength,

moreover, through these holes in the condenser parts of the resonators of all sections, radio-transparent milk pipelines are laid, with a cross-section of less than two wave penetration depths,

in this case, on the side surfaces of each resonator along the perimeter of the bases with a shift of 120 degrees, waveguides with air-cooled magnetrons are installed, the emitters of which are directed to the capacitor parts through corresponding ceramic cylindrical mirrors located coaxially on the internal surfaces of the resonators,

Moreover, in the open spaces of the outer resonators there are slowing non-ferromagnetic spiral devices made in the form of non-ferromagnetic cylinders without bases, with coaxially located non-ferromagnetic spirals with a constant pitch, less than a quarter of the wavelength, through which radio-transparent milk pipelines are laid.

Advantages of the developed installation:

- preservation of taste and consumer qualities of pasteurized milk;

- suppression of the proliferation of bacterial microflora;

- reduction of specific energy costs for pasteurization of milk;

- partial homogenization due to molecular friction during transportation through radiotransparent milk pipelines.

The essence of the invention is illustrated by drawings, which show:

- spatial image of a microwave milk pasteurizer, general view (Fig. 1);

- spatial image of a microwave milk pasteurizer, general cross-sectional view, with positions (Fig. 2);

- spatial image of a microwave milk pasteurizer, cut in half (Fig. 3);

- spatial image of a microwave milk pasteurizer, sectioned at an angle of 45 degrees (Fig. 4);

- spatial image of a quasi-stationary toroidal resonator (Fig. 5);

- spatial image of a ceramic cylindrical mirror (Fig. 6);

- spatial image of a slowing non-ferromagnetic spiral element (Fig. 7);

Microwave milk pasteurizer contains (Fig. 1-5):

- non-ferromagnetic quasi-stationary toroidal resonators 1, 2, 3, 4, 5, 6 corresponding sections;

- non-ferromagnetic cylinder 7 without bases in the last resonator 6;

- non-ferromagnetic spiral 8 in the last resonator;

- toroidal part 9 of a quasi-stationary toroidal resonator;

- capacitor part 10 of the resonator;

- base 11 of the resonator;

- small base 12 of the capacitor part 10 of the resonator;

- holes 13 of the radiotransparent milk pipeline;

- ceramic mirror 14 in the form of a cylinder;

- non-ferromagnetic cylinder 15 without bases in the first resonator 1;

- non-ferromagnetic spiral 16 in the first resonator;

- radiotransparent milk pipelines 17;

- waveguides with air-cooled magnetrons 18.

The microwave milk pasteurizer contains interconnected sections of dual quasi-stationary toroidal resonators (1-6) connected by bases.

Each resonator is presented in the form of a torus 9 of rectangular cross-section and a capacitor part 10 formed by a parallel base 11 of the resonator and a small base 12, where holes 13 are provided in them, with a diameter of less than a quarter of the wavelength, located evenly around the circles so that the distance between the holes is more than a quarter dynes of the wave. Through these holes in the capacitor parts of 10 resonators of all sections, radio-transparent milk pipelines are laid, 17 with a cross-section of less than two wave penetration depths.

Waveguides with air-cooled magnetrons 18 are installed on the side surfaces of each resonator along the perimeter of the bases with a shift of 120 degrees, the emitters of which are directed to the capacitor parts through corresponding ceramic cylindrical mirrors 14 located coaxially on the internal surfaces of the resonators.

In the first 1 and last 6 resonators, slowing non-ferromagnetic spiral devices are placed in their open spaces, in front of the small bases of the capacitor parts. Each device is made in the form of a non-ferromagnetic cylinder 15 with a coaxially located non-ferromagnetic spiral 16 with a constant pitch, less than a quarter of the wavelength, and a spiral diameter less than the diameter of the cylinder through which radio-transparent milk pipelines 17 are laid.

The progress of pasteurization of milk in a microwave pasteurizer occurs as follows.

A single technological line for flash pasteurization of milk contains, in front of the first section of resonators, an equalization tank with a milk pump and a manifold group of control valves for distributing milk through pipes, and behind the last section of resonators there is another equalization tank with a pump for pumping it into a plate milk cooler.

Milk is supplied to the microwave pasteurizer using a pump from the surge tank. To do this, turn on the pumps in front and behind the microwave pasteurizer, then the milk flows through radio-transparent milk lines 17 through a slowing non-ferromagnetic spiral device (15, 16). Thanks to this device, the intensity of the electric field formed by electromagnetic radiation from the resonator through the holes intended for laying radio-transparent milk pipelines drops sharply with distance from the surface of the spiral, so the electric field strength is insignificant. This device works as a transcendental waveguide, despite the fact that its dimensions are comparable (diameter and height of the non-ferromagnetic cylinder 15).

The designed multi-section microwave pasteurizer ensures electromagnetic safety during continuous pumping of milk in a radio-transparent milk pipeline 17 through quasi-stationary toroidal resonators (1-6), where holes 13 are provided in the bases less than a quarter of the wavelength. This is facilitated by a non-ferromagnetic spiral 16 with a constant pitch, less than a quarter of the wavelength. The small power flow of electromagnetic radiation from the holes 13 is damped due to the special design of the slow-down non-ferromagnetic spiral device (15, 16).

If there is milk in the radio wave pipelines 17, all microwave generators 18 should be turned on at a certain power.

When pumped through quasi-stationary toroidal resonators, milk is exposed to an electromagnetic field of ultrahigh frequency (EMF), heats up, and there is no heating between sections, i.e. pause, the temperature equalizes along the diameter of the milk pipeline, since depending on the fat content of the milk, the penetration depth of the wave is different. Repeated exposure to a high-intensity electric field after a pause ensures gentle heating of milk to a temperature of no more than 76-78°C. In this case, it is recommended to maintain a duty ratio of the technological process of less than 0.5, i.e. The duration of exposure to microwave emfs is less than the duration of the pause. This will preserve the basic properties of milk (consistency, taste, smell). The capacitor part of the quasi-stationary toroidal resonator provides a high electric field strength (1.5-2 kV/cm), sufficient for milk disinfection.

Pasteurized milk accumulates in a surge tank, from there it is pumped into a plate milk cooler, for example OM-1.

The number of generators and their power affect the productivity of the pasteurizer, while the power and productivity of the pumps must be matched with the specific power of the generators. Using a manifold group of control valves, you can change the flow of milk through the pipes and the number of pipes through which milk is pumped, therefore, you can regulate the specific power of the generator as the ratio of the power of the generator to the volume of milk in the resonator.

Information sources:

1. Pasteurization of milk. Pasteurization methods. Electronic resource. Access mode: promplace.ru> Articles> Pasteurization of milk. Date of access: 09/06/2022.

2. Technology and technology of milk processing. S.A. Bredikhin. Books and textbooks. Electronic resource. Access mode: obuchalka.org>>. Date of access: 09/07/2022.

3. Patent No. 2432764 of the Russian Federation, IPC A23S 3/07. Installation for heat treatment of liquids / Kirillov N.K., Novikova G.V., Kirillov N.K. Ponomarev A.N.; applicant and patent holder ChGSHA (RU). - No. 2010101205/13 (001600); application 01/15/2010. Bull. No. 28 dated November 10, 2011. - 12 s.

4. Patent No. 2708989 of the Russian Federation, IPC A23 L3/01. Microwave installation for pasteurization of mastitis milk / Novikova G.V., Tarakanov D.A., Shamin E.A., Mikhailova O.V., Belova M.V., Krainov Yu.E.; applicant and patent holder NSIEU (RU). - No. 2018139246; application 10/08/2018. Bull. No. 35 dated 12/12/19. - 13 s.

5. Strekalov A.V., Strekalov Yu.A. Electromagnetic fields and waves - M.: RIOR: INFRA-M, 2014. - 373 p.

6. Pchelnikov Yu.N., Sviridov V.T. Ultrahigh frequency electronics. - M.: Radio and communication, 1981. - 96 p.

7. Baskakov S.I. Electrodynamics and wave propagation. - M.: Energoizdat, 1992. - 208 p.

Claims (1)

A microwave pasteurizer of milk containing connected sections of dual quasi-stationary toroidal resonators, docked at the bases, with each resonator represented in the form of a torus of rectangular cross-section and a capacitor part formed by a parallel resonator base and a small base, with holes provided in them with a diameter of less than a quarter of the wavelength, located evenly around the circles so that the distance between the holes is more than a quarter of the wavelength, and through these holes in the condenser parts of the resonators of all sections, radio-transparent milk pipes are laid with a cross-section of less than two wave penetration depths, while they are installed on the side surfaces of each resonator along the perimeter of the bases with a shift of 120 degrees waveguides with air-cooled magnetrons, the emitters of which are directed to the capacitor parts through corresponding ceramic cylindrical mirrors located coaxially on the internal surfaces of the resonators, and in the open spaces of the outer resonators there are slowing non-ferromagnetic spiral devices made in the form of non-ferromagnetic cylinders without bases, with coaxially located non-ferromagnetic spirals with a constant step of less than a quarter of the wavelength, through which radio-transparent milk pipelines are laid.