RU2118886C1 - Liquid pasteurization (sterilization) and microwave energy take-off apparatus - Google Patents

Abstract

FIELD: food-processing industry, medicine, may be used in radio engineering, in particular, pasteurization (sterilization) of liquid water-containing substances and preparations not adapted for prolonged high temperature heating actions. SUBSTANCE: apparatus has metal waveguide, whose one end is adapted for introducing microwave energy and other shirt-circuited end defines half-wave resonator. Resonator connection element is made in the form of resonant series circuit having syphon disposed in central part of wide waveguide wall and axially aligned relative to adjusting screw mounted in opposite wall of waveguide. Syphon is composed of axially aligned inner and outer pipes arranged in spaced relation between inner surface of outer blind end pipe and outer surface of inner pipe, and between inner pipe end and blind part of outer pipe. Such construction allows apparatus to be used as resonant microwave loading and antenna equivalent. EFFECT: wider operational capabilities, increased temperature gradient of liquid under treatment process and, as a result, improved quality of treated liquid. 2 cl, 1 dwg

Description

 The invention relates to the food industry, medicine, and also to radio engineering, and can be used in devices for pasteurization (sterilization) of liquid food products (for example, milk, beer, wine) and medicines, the water-containing substances of which do not allow prolonged high-temperature heating, and also in devices for resonant selection of microwave power (for example, in waveguide loads and equivalent antennas).

 A device for pasteurization (sterilization) of liquid food products with microwave energy, containing a metal waveguide of rectangular cross section, one end of which is designed to input microwave energy, the final coordinated load, a pipe made of radio-transparent material, collections, characterized in that the pipeline is removable, has circular cross section and passes through the wide walls of the waveguide, on the outer sides of which perpendicular to their plane hollow metal cylinders are strengthened for the passage of the pipeline in one of the transverse plane with the pipeline, a metal adjusting screw is introduced into the waveguide, and the pipeline with liquid, metal cylinders and the adjusting screw are a quasi-focused resonator, the final matched load is made in the form of a short-circuit piston, and a flow presence sensor is installed at the initial section of the pipeline.

The inner diameter of the pipeline d1 is 0.182a, the outer diameter of the pipeline d2 is equal to the inner diameter of the metal cylinders and is 0.202a, the diameter of the metal adjusting screw d3 is 0.164a, the pipeline and the adjusting screw are offset from the longitudinal axis of the waveguide by a distance l ₁ equal to 0, 19a, the distance from the axis of the pipeline to the short-circuit piston l ₂ is equal to 0.58a, where a is the size of the wide waveguide wall [1].

 The device according to the application [1] is the closest analog device and is selected as a prototype.

 The disadvantages of the prototype device is the low heating gradient. Performed in accordance with the claimed size ratios, the device according to the application [1] makes it possible to ensure the density of the applied microwave power of 100 W per 1 g of the processed liquid. Reducing the height of the waveguide (in order to reduce the volume of the fluid being processed in the pipeline between the wide walls of the waveguide) is limited by the possibility of high-frequency breakdown between the metal adjusting screw and the opposite wall of the waveguide, and reducing the diameter of the pipeline for the same purpose is limited by the fact that when the ratio of its diameter to it the length in the working area greater than or equal to 20, boiling up of the treated liquid occurs and, as a result, a rough mismatch of the quasi-concentrated resonator.

 The purpose of the invention is to increase the temperature gradient of the processed fluid and, as a consequence, to improve the quality of processing.

This goal is achieved by the fact that in the known device, in the center of the wide wall of the waveguide, a siphon is introduced containing an external (supply) plugged pipe and an internal (output) coaxial pipe, the gap width between them being 0.01λ _o , where λ _o is the wavelength at the resonant frequency; the outer diameter of the liquid column enclosed in the siphon and the minimum immersion depth of the siphon in the waveguide are determined by the minimum available volume of liquid at which the operating mode of the microwave energy source is not disturbed and at which the density of the applied microwave power is 100 W per 0.05 g of the processed material, which allows to increase the processing speed upon reaching a higher heating rate and, therefore, to improve the quality of processing; an adjusting screw with an end part diameter not less than the diameter of the liquid column in the siphon is inserted into the opposite wide wall of the waveguide coaxially with the siphon and form a series resonant circuit, which is the resonant diaphragm of the half-wave 1 / 2λ90 short-circuited resonator, where λ90 is the wavelength in the waveguide at the resonant frequency .

 Collapsible siphon simplifies the replacement of radiotransparent pipes and sanitary treatment, which ensures high quality of the processed fluid. The ability to provide electrical contact between the treated fluid and the waveguide completely eliminates spurious emissions from the heating chamber.

 The heating chamber of the device is made in the form of a combination of a half-wave resonator, one end of which is short-circuited, and a sequential oscillatory circuit, which is the resonant diaphragm of the resonator. The series circuit is formed by the inductance of the adjusting screw and a part of the siphon immersed in the waveguide, as well as by the capacitance between the end of the screw and the siphon on the opposite wide wall of the waveguide.

 In the proposed device, the value of KCBH ≤ 1.2 and the utilization of microwave energy is not less than 95%, which is no worse than the values of the same parameters provided by the prototype device, and the heating rate in the proposed device is 20 times higher.

 The combination of newly introduced structural and electrical features does not follow explicitly from the prior art, which allows us to conclude that the proposed device for pasteurization (sterilization) of liquid, as well as the selection of microwave power should be considered new and inventive.

 The drawing shows the proposed device for pasteurization (sterilization) of the liquid, as well as the selection of microwave power.

The device contains a metal short-circuited waveguide 1, one end of which is designed to input microwave power, a siphon 2 made of radiolucent material with a gap width between the inner surface of the outer pipe and the outer surface of the inner pipe equal to 0.01λ _o , the housing 3 is made of metal that allows contact with the processed fluid, for fastening the elements of the siphon, as well as the input and output of the processed fluid, an adjusting screw 4, with a diameter of the end part not less than the diameter of the liquid column in the siphon, coaxial with the siphon and aspolozhenny in the center of the broad wall of the waveguide.

The device operates as follows. The resonant frequency of the device is determined by a half-wave resonator 1 / 2λ ₉₀ short-circuited on one side and excited by a resonant diaphragm with active resistance formed by the inductance of the adjusting screw 4 and a part of the siphon 2 immersed in the waveguide 1 and the capacitance formed by the end of the adjusting screw and the end of the siphon on the opposite wall waveguide, as well as the active resistance of the processed fluid with a large attenuation coefficient located in the siphon. The resonant diaphragm is adjusted using the adjusting screw 4. The processed fluid is introduced into the housing 3, filled of metal that can be contacted with the treated fluid, enters the end of the siphon 2 through a gap equal to 0.01λo and, having absorbed almost all the power, is removed from the radiolucent tube from cameras. An insignificant part of the power not absorbed by the liquid, having excited the half-wave resonator, again falls on the resonant diaphragm, giving off the energy of the processed liquid.

 Resonance in a series circuit is characterized by the highest current value and the energy applied to the circuit completely falls on the active resistance. The geometric dimensions of the working area of the siphon provide a power flux density of 100 W per 0.05 g of the processed fluid, and the location of the circuit elements in the center of a wide degree of the waveguide ensures a uniform distribution of bias currents around the siphon perimeter.

 Due to the fact that the liquid being treated is electrically closed with the waveguide through the housing 3, microwave radiation is practically excluded.

 Thus, the proposed device is characterized by a high temperature gradient, processing speed, the quality of the resulting product; simplicity and low metal consumption of the design, great reliability and safety of service.

Sources of information
1. Application for the invention of the Russian Federation N 94004541/13 (004194) from 02/08/94; IPC 6 A 23 L 3/01, F 23 L 3/32; "Device for pasteurization (sterilization) of liquid food products with microwave energy", Chekrygina IM, Cherednichenko VP, Karlov AF, Nosovets AF

Claims (2)

 1. The device for pasteurization (sterilization) of the liquid, as well as the selection of microwave power, containing a metal waveguide of rectangular cross section, one end of which is designed to input microwave energy, an adjustment screw, characterized in that the other end of the waveguide is short-circuited and forms a half-wave resonator, a communication element which is a resonant series circuit consisting of a siphon mounted in the center of the wide wall of the waveguide coaxially with the adjusting screw located on the opposite wall of the wave ode, the siphon is formed of coaxial inner and outer tubes of radiotransparent anechoic material with a gap between the inner surface of the outer tube plugged and the outer surface of the inner tube, as well as between the end of the inner tube and the outer part plugged. 2. The device according to claim 1, characterized in that the width of the gap of arbitrary length between the inner surface of the outer muffled pipe and the outer surface of the inner pipe of the siphon, as well as between the end of the inner pipe and the muffled part of the outer, is 0.01 λ ₀ , where λ ₀ - the wavelength at the resonant frequency, the diameter of the liquid enclosed in the siphon between the inner walls of the outer pipe, and the immersion depth of the siphon are selected from the condition under which 0.05 g of the processed liquid falls on every 100 W of applied power, the diameter of the torus the central part of the adjusting screw is not less than the diameter of the liquid column in the siphon, and the cavity length is 1/2 λ ₀ , where λ ₀ is the wavelength in the waveguide at the resonant frequency.