RU2792675C1 - Microwave-convective hop dryer with semi-cylindrical resonators and fluoroplastic comb guides - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: microwave-convective hop dryer with semi-cylindrical resonators and fluoroplastic comb guides comprises connected sections of equal-sized non-ferromagnetic resonators in the horizontal plane, made in the form of joined semi-cylinders (3, 15, 27) and prismatic bases of rectangular section (11, 23, 35). Equal-sized perforated PTFE comb guides (5, 17, 29) with combs directed towards the prismatic base (11, 23, 35) are rigidly installed into non-ferromagnetic cylinders (3, 15, 27), with a height that is a multiple of half the wavelength, the comb pitch of no more than two wave penetration depths and the comb thickness less than the pitch value. In non-ferromagnetic prismatic bases (11, 23, 35), dielectric mesh conveyors (12, 24, 36) are installed coaxially under perforated fluoroplastic comb guides (5, 17, 29) with a length equal to the length of the resonators, with electric drives located outside the resonators. Perforated ceramic concave mirrors (13, 25, 37) are rigidly fixed between the working and idle branches of the mesh conveyors (12, 24, 36), covering the area of the working branches of the corresponding conveyors (12, 24, 36). The bases of non-ferromagnetic resonators are represented by non-ferromagnetic end faces (6, 10, 18, 22, 30, 34) of perforated fluoroplastic comb guides (5, 17, 29), non-ferromagnetic segments (4, 9, 16, 21, 28, 33) above them and rectangular ends of prismatic bases (11, 23, 35). Non-ferromagnetic air ducts (14, 26, 38) are directed against the movement of raw materials under perforated ceramic mirrors (13, 25, 37) from the side of one end of each non-ferromagnetic resonator, and from the other end on the surfaces of non-ferromagnetic half-cylinders (3, 15, 27) air vents are installed – evanescent waveguides (8, 20, 32). A non-ferromagnetic loading container (2) is attached to the base of the non-ferromagnetic resonator of the first section, where a non-ferromagnetic grid loading conveyor (1) is installed at the level of the grid dielectric conveyor (12). A non-ferromagnetic receiving container (39) in the form of a truncated conical prism is attached to the base of the resonator of the last section, inside which a non-ferromagnetic cellular drum (40) is installed with a length equal to the width of the dielectric mesh conveyor (36). All mesh conveyors (12, 24, 36) are located on the same level. Air-cooled magnetrons (7, 19, 31) with waveguides are mounted on the surface of each non-ferromagnetic half-cylinder (3, 15, 27) with a helical shift.

EFFECT: preservation of consumer properties of dried disinfected hops.

1 cl, 9 dwg

Description

The invention relates to the field of agriculture and can be used in hop-growing farms for the gradual drying of freshly harvested hops in a continuous mode while maintaining consumer properties.

Known hop dryer XC-400, based on the convective method of heat supply [1]. Disadvantages: high energy costs; uneven coloring of the golden-green shade of crushed hop cones; lengthy drying process for freshly harvested hops.

Known microwave convective hop dryer with curved resonator surfaces containing ceramic mirrors [2, patent No. 2772987], [3, patent No. 2772992]. The disadvantage is the difficulty of matching the thickness of the hop layer with the penetration depth of the electromagnetic wave (2.5−3 cm) centimeter range, which leads to uneven dielectric heating of the hop.

The closest in technical essence is the well-known microwave convective continuous-flow hop dryer with a hemispherical resonator [4, patent No. 2770628]. Hemispherical non-ferromagnetic resonator is docked coaxially with the cylindrical part of the hop dryer, air ducts with an electric heater are attached to its side surface. The hemispherical resonator is divided into zones by ceramic perforated biconvex baffles. At the top of the resonator, air vents from each zone and a loading hopper are installed. A dielectric distributor is installed under the bunker.

The disadvantages are difficulties in step-by-step regulation of the rate of heating and drying of freshly harvested hops.

Therefore, the development of a continuous-flow hop dryer with sources of convective heat supply and microwave energy for selective exposure to an electromagnetic field of microwave frequency (EMSHF, 2450 MHz, wavelength 12.24 cm) andceramic mirrors,focusing the energy of electromagnetic radiation in the volume of raw materials, as well asfluoroplastic guides, increasing the uniformity of drying in thickness, relevant.

An analysis of known technical solutions has shown that a technical problem in this area is the need to expand the arsenal of tools used for the staged drying of freshly harvested hops in a continuous mode while maintaining consumer properties.

The main criteria for designing a hop dryer with microwave generators and electric air heaters are: acceleration of step-by-step uniform drying of freshly harvested hops; continuous-line mode of operation; providing different temperature conditions and different electric field strengths in the resonators; electromagnetic safety (without the use of a shielding case) when using air-cooled magnetrons.

The technical result of the invention is the preservation of consumer properties of dried disinfected hops.

To solve the technical problem and achieve the claimed technical result, the microwave convective hop dryer contains in the horizontal plane connected sections of equal-sized non-ferromagnetic resonators made in the form of joined half-cylinders and prismatic bases of rectangular cross section,

at the same time, perforated fluoroplastic comb guides of equal size are installed in non-ferromagnetic half-cylinders coaxially rigidly, with combs directed towards the prismatic base, with a height that is a multiple of half the wavelength, a comb pitch of not more than two wave penetration depths and a comb thickness significantly less than the pitch value,

moreover, in the non-ferromagnetic prismatic bases, coaxially, under the perforated fluoroplastic comb guides, dielectric mesh conveyors are installed, with a length equal to the length of the resonators, with electric drives located outside the resonators, and between the working and idle branches of the mesh conveyors, perforated ceramic concave mirrors are rigidly fixed, covering the area of the working branches of the corresponding conveyors ,

and the bases of non-ferromagnetic resonators are represented by non-ferromagnetic facings of the ends of perforated fluoroplastic comb guides, non-ferromagnetic segments above them and rectangular ends of prismatic bases,

at the same time, non-ferromagnetic air ducts are directed against the movement of raw materials under perforated ceramic mirrors from the side of one end of each non-ferromagnetic resonator, and from the side of the other end, on the surfaces of non-ferromagnetic half-cylinders, air vents - transcendental waveguides are installed,

moreover, a non-ferromagnetic loading container is attached to the base of the non-ferromagnetic resonator of the first section, where a non-ferromagnetic grid loading conveyor is installed at the level of the grid dielectric conveyor, and a non-ferromagnetic receiving container is attached to the base of the resonator of the last section in the form of a truncated conical prism, inside which a non-ferromagnetic cellular drum is installed, the length is equal to the width dielectric mesh conveyor,

in this case, all mesh conveyors are located at the same level, and air-cooled magnetrons with waveguides are installed on the surface of each non-ferromagnetic half-cylinder with a helical shift.

The use of microwave heating of the moving raw materials can significantly increase the productivity of the installation. But at the same time, the main disadvantages of these installations are the complexity of the shielding structures, the uneven cross-section of the raw material (the uneven heating in thickness) and electrical breakdowns at its high humidity. If the uniformity of heat release over the cross section is not achieved, then the temperature equalization occurs due to thermal conductivity, and then, in order not to overheat areas with a strong electric field, it will be necessary to reduce the power of the microwave generator and lengthen the drying time. As a result, the benefits of microwave heating are reduced. These shortcomings can be eliminated by using a metal-dielectric resonator as the basis of the drying chamber, i.e. using a fluoroplastic guide of a special design in a non-ferromagnetic resonator, for example, a fluoroplastic comb guide, which makes it possible to equalize the layer thickness in accordance with two depths of wave penetration into the hops (5-6 cm). The concentration of the energy of the electromagnetic field in the volume of the resonator and the reduction of radiation losses can be achieved by using a ceramic mirror with low dielectric losses. If a non-ferromagnetic resonator contains fluoroplastic and ceramic elements, then such a resonator is called metal-dielectric.

It is known that there are a large number of different types of surface wave transmission lines. The most widely used are metal-dielectric resonators containing dielectric plates or combs in non-ferromagnetic resonators of various designs. The nature of the distribution of surface electromagnetic waves along the dielectric comb is complex. The surface wave field above the PTFE comb guide has an exponentially decreasing character. In this case, the comb pitch is small compared to the wavelength (12.24 cm, 2450 MHz), and the tooth thickness is much less than the pitch [5, p. 98]. For the existence of a surface wave, it is necessary that the condition be fulfilled: the height of the fluoroplastic comb guide is a multiple of a quarter of the wavelength.

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

- spatial image of a microwave-convective hop dryer with semi-cylindrical resonators and perforated fluoroplastic comb guides, general view (Fig. 1);

- spatial image of a microwave-convective hop dryer with semi-cylindrical resonators and perforated fluoroplastic comb guides, a general view in the section of the fourth part (Fig. 2);

spatial image of a microwave-convective hop dryer with semi-cylindrical resonators and perforated fluoroplastic comb guides, a general view in section with positions (Fig. 3);

- spatial image of a microwave-convective hop dryer with semi-cylindrical resonators and perforated fluoroplastic comb guides, indicating the direction of movement of raw materials and air (Fig. 4);

- spatial image of a non-ferromagnetic resonator (Fig. 5);

- spatial image of the dielectric mesh conveyor (Fig. 6);

- spatial image of a fluoroplastic perforated comb guide with non-ferromagnetic end facings (Fig. 7);

- spatial image of a perforated concave ceramic mirror (Fig. 8);

- spatial image of a non-ferromagnetic cellular drum (Fig. 9);

Microwave convective hop dryer with semi-cylindrical resonators and fluoroplastic comb guides contains (Fig. 1−9):

- non-ferromagnetic mesh loading conveyor 1 with electric drive;

- loading capacity 2 of non-ferromagnetic material;

- non-ferromagnetic half-cylinders 3, 15, 27 of the corresponding sections of the hop dryer;

- non-ferromagnetic segments 4, 9, 16, 21, 28, 33 on the bases of non-ferromagnetic semi-cylinders of the respective sections of the hop dryer;

- perforated fluoroplastic comb guides 5, 17, 29 of the corresponding sections of the hop dryer;

- non-ferromagnetic facings 6, 10, 18, 22, 30, 34 of the end sides of the perforated fluoroplastic comb guides of the corresponding sections of the hop dryer;

- air-cooled magnetrons with waveguides 7, 19, 31 on the surfaces of the semi-cylinders of the corresponding sections of the hop dryer;

- non-ferromagnetic air vents - transcendental waveguides 8, 20, 32 on the surface of the semi-cylinders of the corresponding sections of the hop dryer;

- non-ferromagnetic prismatic bases of rectangular section 11, 23, 35 resonators of the corresponding sections of the hop dryer;

- dielectric mesh conveyors 12, 24, 36 with electric drives of the corresponding sections of the hop dryer;

- perforated concave ceramic mirrors 13, 25.37 of the corresponding sections of the hop dryer;

- non-ferromagnetic air ducts 14, 26, 38 with thermal electric guns of the corresponding sections of the hop dryer;

- non-ferromagnetic receiving capacity 39 in the form of a truncated conical prism;

- non-ferromagnetic cellular drum 4.

Microwave-convective hop dryer with semi-cylindrical resonators and fluoroplastic comb guides is assembled from sections (Fig. 1−9). Each resonator consists of a non-ferromagnetic half-cylinder (3, 15, 27) coupled to a non-ferromagnetic prismatic base of rectangular cross section (11, 23, 35). Each non-ferromagnetic resonator is presented as a half-cylinder, docked with a rectangular prismatic base. The ends of the resonators are closed with non-ferromagnetic segments and non-ferromagnetic facings of the ends of the comb guides. But, between the combs there are open spaces (slots for the movement of raw materials).

Perforated PTFE comb guides (5, 17, 29) are located in each non-ferromagnetic half-cylinder (3, 15, 27). Their end sides are lined with non-ferromagnetic material (6, 10, 18, 22, 30, 34).

In each non-ferromagnetic prismatic base (11, 23, 35) there are dielectric mesh conveyors (12, 24, 36) with electric drives located outside the dryer. Between the working and idle branches of each dielectric mesh conveyor there are perforated ceramic concave mirrors (13, 25, 37). Their width is equal to the diameter of the half-cylinder, and their length is equal to the length of the resonator. Non-ferromagnetic air ducts (14, 26, 38) from the corresponding heat guns are directed under perforated ceramic mirrors from one end of the resonator (opposite to the movement of raw materials), and from the other end of the resonator on the surface of the half-cylinder there are air outlets - transcendental waveguides (8, 20, 32).

A non-ferromagnetic receiving container (39) in the form of a truncated conical prism is attached to the end side of the resonator of the last section of the hop dryer. The number of sections depends on the required capacity of the hop dryer. Inside the receiving container 39 in the conical part, across the width of the mesh dielectric conveyor 36, there is a non-ferromagnetic cellular drum 40 for unloading dried hops.

Technological process of drying freshly harvested hops.

To implement an effective drying mode, the following control options are provided:

- rotational speeds of the corresponding electric motors of the conveyors (12, 24, 36) and the cellular drum (40);

- performance of fans and power of the corresponding heat guns (14, 26, 38);

- the volume of loading of raw materials into the resonator with a change in the speed of the electric motor of the loading conveyor 1;

- power of microwave generators (5, 15, 22);

- specific power of the generators, as the ratio of the power of the generators to the volume of loading of raw materials into the resonator.

A high electric field strength (1.8–6 kV/cm) in each non-ferromagnetic resonator is provided by the interference of concentrated coherent waves from perforated ceramic mirrors (13, 25, 37), which have a small value of the dielectric loss tangent, and due to the surface wave on perforated PTFE comb guides (5, 16, 29).

Turn on all electric heat guns (14, 26, 38) to the appropriate fan performance and heating element power.

Turn on the electric drives of the dielectric mesh conveyors in the following sequence: the last one (36), the middle one (24) and the first one (12), then the electric drive of the non-ferromagnetic mesh conveyor (1). Load freshly harvested hop cones into a non-ferromagnetic loading container 2. Wet raw material is moved using a non-ferromagnetic mesh conveyor 1 and distributed using a fluoroplastic comb guide 5. As soon as using a dielectric mesh conveyor 12, the raw material will move into the space between the perforated combs, the width of which is equal to two penetration depths waves, it is necessary to turn on the generator 7. Then, in the resonator 3, an electromagnetic field of ultrahigh frequency (EMSHF) is excited, the raw material is endogenously heated. Due to the interference of a surface wave from a fluoroplastic comb guide 5 and a concentrated wave from a ceramic mirror 13, an electric field of high intensity is excited in the resonator, sufficient to disinfect the raw material during its uniform endogenous heating. Surface moisture from the hop cones is removed by warm air entering through the perforated ceramic mirror 13 under the working branch of the dielectric mesh conveyor 12 from the non-ferromagnetic duct 14 connected to the corresponding heat gun. Humid air is removed through a non-ferromagnetic air vent-beyond waveguide 8.

Due to the fact that all mesh dielectric conveyors are located close to each other at the same level, the raw material enters the space between the perforated combs of the fluoroplastic guide 17 of the second non-ferromagnetic resonator 15. Drying of the raw material in the second non-ferromagnetic resonator, distributed in the space between the perforated fluoroplastic combs, occurs uniformly across the width, since the step between the combs is no more than two wave penetration depths. In this case, the circulation of warm air occurs through the air duct 26 and the air outlet 20.

Similarly, the process of drying raw materials continues in the subsequent non-ferromagnetic resonator 27. Dried in a gentle mode, hop cones from the PTFE perforated comb guide 29 with the help of a conveyor 36 fall into a non-ferromagnetic receiving container 39, from where, using a non-ferromagnetic cellular drum, it is unloaded into a container designed for transporting dry hops .

Such a hop dryer provides gradual removal of moisture from hop cones during the movement of raw materials by dielectric mesh conveyors (12, 24, 36) through non-ferromagnetic resonators (3, 15, 27). At the same time, hop cones are subjected to endogenous-convective heating, dried and disinfected due to the high electric field strength, i.e. there is a preservation of consumer characteristics and improvement of microbiological indicators.

In all resonators, the dose of exposure to EMSHF, temperature and pressure of the supplied air are controlled and regulated depending on the humidity and volume of the loaded hop by changing the power of the generators, heating elements and air flow, as well as changing the speed of the electric drives of the mesh conveyors. All elements of the control system are located in the control cabinet, and the electric motors are located outside the resonators.

Due to non-ferromagnetic containers (2, 39) and a non-ferromagnetic cellular drum for unloading hops, as well as due to non-ferromagnetic segments and non-ferromagnetic facings of the ends of fluoroplastic comb guides (6, 10, 18, 22, 30, 34), electromagnetic safety is ensured within acceptable standards. At the same time, the open spaces between the fluoroplastic combs (slots for moving raw materials) in the first and last resonators, with proper coordination with the wave penetration depth (no more than two wave penetration depths), limit electromagnetic radiation, since the field of the surface wave under the comb has an exponentially decreasing character. [5, p. 98].

Ceramic concave mirrors make it possible not only to concentrate the energy of the electromagnetic field, but also to reduce radiation losses through the open spaces between the combs [6].

Information sources:

1. Decree No. 738-r on approval of the Concept for the Development of Hop Growing in the Chuvash Republic for 2020-2025. [Electronic resource]. Access mode: km.cap.ru›doc/laws/2020/08/20/disposal-738-r.

2. Patent No. 2772987 RF, IPC C12C3/02; F26B3. Multicavity hop dryer with energy supply in an electromagnetic field / Prosviryakova M.V., Storchevoy V.F., Goryacheva N.G., Mikhailova O.V., Novikova G.V. / applicant and patent holder RGAU-MSHA named after K.A. Timiryazev (RU). No. 2021132821 dated 11/11/2021. Bull. No. 16 dated 05.30.2022.

3. Patent No. 2772992 RF, С12С3/02; F26B3. Hop dryer with toroidal and astroidal resonators with energy supply in an electromagnetic field / Prosviryakova M.V., Storchevoi V.F., Goryacheva N.G., Novikova G.V., Mikhailova O.V., Ziganshin B.G. / applicant and patent holder NGIEU (RU). No. 2021135280 dated 12/01/2021. Bull. No. 16 dated 05/30/2022.

4. Patent No. 2770628 RF, С12С3/02; F26B3. Microwave-convective continuous-flow hop dryer with a hemispherical resonator / Prosviryakova M.V., Storchevoy V.F., Goryacheva N.G., Novikova G.V., Mikhailova O.V., Ziganshin B.G. / applicant and patent holder NGIEU (RU). No. 2021136688 dated 12/13/2021. Bull. No. 11 dated 04/19/2022.

5. Baskakov S.I. Electrodynamics and wave propagation. Moscow: Higher school, 1992, 208 p.

6. Dielectric resonators. Edited by M.E. Ilchenko. M.: Radio communication, 1989. 328 p.

Claims (1)

Microwave-convective hop dryer with semi-cylindrical resonators and fluoroplastic comb guides, characterized in that it contains connected sections of equal-sized non-ferromagnetic resonators in the horizontal plane, made in the form of joined semi-cylinders and prismatic bases of rectangular cross section, while non-ferromagnetic semi-cylinders are coaxially rigidly mounted equal in size perforated fluoroplastic comb guides with combs directed towards the prismatic base, with a height that is a multiple of half the wavelength, the comb pitch is not more than two wave penetration depths and the comb thickness is less than the pitch, moreover, dielectric mesh conveyors are installed in non-ferromagnetic prismatic bases coaxially under the perforated fluoroplastic comb guides length equal to the length of the resonators, with electric drives located outside the resonators, and between the working and idle branches of the mesh conveyors perforated ceramic concave mirrors are rigidly fixed, covering the area of the working branches of the corresponding conveyors, and the bases of the non-ferromagnetic resonators are represented by non-ferromagnetic facings of the ends of the perforated fluoroplastic comb guides, non-ferromagnetic segments above them and rectangular ends of the prismatic bases, while the non-ferromagnetic air ducts are directed against the movement of raw materials under the perforated ceramic mirrors with side of one end of each non-ferromagnetic resonator, and from the side of the other end on the surfaces of non-ferromagnetic semi-cylinders, air vents are installed - transcendental waveguides, and a non-ferromagnetic loading container is attached to the base of the non-ferromagnetic resonator of the first section, where a non-ferromagnetic grid loading conveyor is installed at the level of the grid dielectric conveyor, and to the base of the resonator the last section is attached to a non-ferromagnetic receiving container in the form of a truncated of this conical prism, inside which a non-ferromagnetic cellular drum is installed with a length equal to the width of the dielectric mesh conveyor, while all mesh conveyors are located at the same level, and air-cooled magnetrons with waveguides are installed on the surface of each non-ferromagnetic half-cylinder with a helical shift.

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