EA021551B1 - Device for microwave heating of dielectric mediums - Google Patents

Abstract

The invention relates to microwave technology and can be used for heating different dielectric mediums, including ones for heating solidified oil products, in producing viscous oils and natural bitumens in places of extraction thereof, and also for non-mechanical removing icicles from roofs and repair of bitomen-containing moisture-proof coverings of buildings. A device comprises a magnetrone microwave oscillator, a transmitting line matched thereto and a radiator at its end, the transmitting line is made as a coaxial cable, the cable inlet is connected to a coaxial transfer, the inner conductor of which is connected to the microwave oscillator exciter, and the outer conductor to the oscillator body, the radiator is made as a stretch of rectangular metal waveguide, one end of which is cut at an angle to a wide wall and is closed by a dielectric plate fastened at the end providing sealing, the other end is closed by a metal plate perpendicular to the waveguide axis, wherein a hole is made in the waveguide wide wall, in the center of the hole the exciter is fixed at the coaxial cable end, the outer cable armature is connected to the waveguide. The device provides microwave heating of different dielectric mediums and enhancing effectiveness of action by an operative movement of the radiator over the surface of the medium being treated.

Description

The invention relates to microwave equipment and can be used for heating various dielectric media, including when heating frozen petroleum products, during the production of viscous oils and natural bitumen in places of their occurrence, as well as during non-mechanical removal of icicles from roofs of houses and repair of bitumen-containing waterproofing coatings of buildings .

Known devices for microwave heating of dielectric media in which electromagnetic energy from a microwave generator through a transmission line and the emitter is directed to the surface of the processed medium asphalt pavement (RF patent No. 2039145, 1993), liquids (RF patent No. 2087083, 1997 ), petroleum products in the tank (RF patent No. 2224387, 2004). The disadvantage of these devices is the fixed location of the emitter relative to the surface of the medium, not allowing, if necessary, to change the mode or zone of microwave exposure.

The closest in technical essence and the achieved result to the claimed device is a device for heating thickened and solidified oil products in railway tanks according to the patent of the Russian Federation No. 2224387, 2004. It contains a magnetron microwave generator connected to it by a rigid waveguide transmission line and a horn emitter located above the surface of the oily medium in a fixed position. The disadvantage of the prototype is a decrease in the heating rate with a decrease in the level of oil products in the tank, since the microwave power flux density at the surface decreases due to an increase in the distance from the emitter.

The technical problem solved in the present invention is to increase the efficiency of the device by quickly adjusting the position of the emitter relative to the surface of the dielectric medium, as well as expanding the functionality of the device.

The problem is solved in that in the known device containing a magnetron microwave generator, a transmission line matched with it and a radiator at its end, the transmission line is made in the form of a coaxial cable, the beginning of the cable is connected to a coaxial junction, the inner conductor of which is connected to the exciting pin of the microwave generator and the outer one with the generator housing, the emitter is made in the form of a segment of a rectangular metal waveguide, one end of which is cut at an angle to a wide wall and closed by a dielectric plate with astin, fixed at the end to ensure tightness, the other end is closed by a metal plate perpendicular to the axis of the waveguide, while a hole is made in the wide wall of the waveguide, in the center of which there is an exciting pin at the end of the coaxial cable, and the outer braid of the cable is connected to the waveguide.

A flexible coaxial cable with an emitter at the end provides more efficient heating of the medium by quickly moving the emitter along its surface, and a radiolucent dielectric plate hermetically mounted on the cut end allows it to work in a liquid medium, which is an advantage of the claimed device compared to the prototype.

In FIG. 1 shows a diagram of the device, in FIG. 2 - its location during the heating of solidified petroleum products in the tank, in FIG. 3 and 4 are variants of the arrangement of the device under microwave exposure to icicles hanging from the roof, in FIG. 5 - the location of the device on a bitumen-containing roof during its repair using microwave heating.

The device (Fig. 1) contains a magnetron microwave generator 1 with an exciting pin 2, which is connected to the inner conductor of the coaxial junction 3, which serves to coordinate the generator with coaxial cable 4. The flange 5 of the coaxial junction is mounted on the generator body. For the convenience of operation of the device, when replacing the generator or cable, there is a coaxial connector 6 mounted on the end of the coaxial transition, while its inner conductor 7 is connected to the inner conductor of the coaxial connector. A radiator 8 is fixed at the end of the cable, which is made in the form of a segment of a rectangular metal waveguide 9, one end of which 10 is cut at an angle to the wide wall 11 and is closed by a dielectric plate 12 fixed to the end to ensure tightness, the other end is closed by a metal plate 13 perpendicular to axis of the waveguide, while a hole 14 is made in the wide wall of the waveguide, in the center of which a driving pin 15 is fixed at the end of the coaxial cable, and its outer braid is connected to the waveguide.

The end of the waveguide, cut at an angle to a wide wall, adjacent to the boundary of the medium and covered by a radiolucent dielectric plate, provides the maximum passage of the electromagnetic wave from the waveguide into the dielectric medium. This is due to the fact that with such a cut of the end face, the electric field vector is in the plane of incidence of the wave. It is known that with such polarization there is a wave angle φ, measured from the normal to the surface - the so-called Brewster angle, (see, for example, Yu.V. Pimenov, V.I. Volman, A.D. Muravtsev. Technical electrodynamics. M., Radio and communications, 2000, p. 197), at which the reflection coefficient reaches a minimum, and almost all of the energy goes into the medium. To do this, the condition

where ε is the dielectric constant of the medium. Thus, depending on the parameters of the medium, the angle between the cut-off end of the waveguide and its wide wall should be [π / 2 - ageesto] (in radian measure).

- 1 021551

For oil-bearing rocks, the values of ε lie in the range of 2-4 (see, for example, Yu.V. Revizsky, VP Dyblenko. Investigation and justification of the oil recovery mechanism using physical methods, Chapter 4. M, Nedra-business center, 2002). Fresh ice has ε = 3 (see, for example, R. King, G. Smith. Antennas in material media. M., Mir, 1984, v. 1, p.201). Thus, the angle between the cut end of the waveguide and its wide wall should lie within 25-35 degrees.

The location of the device for microwave heating of the medium depends on its nature. For example, for the frozen petroleum products 16 in the reservoir 17 (Fig. 2), a flexible coaxial cable 4 with the emitter 8 at the end with the help of the bracket 18 can move over the entire surface of the medium. For ease of operation, a coaxial connector 19 is installed on the emitter. When the medium is diluted, the emitter can be immersed in the medium to a certain depth due to the sealed radiolucent plate 12, increasing its heating rate.

A flexible coaxial cable with a radiator at the end allows you to expand the device's capabilities for microwave heating of various environments. For example, the inventive device can be used for non-mechanical destruction of icicles hanging from the roofs of buildings. Microwave exposure is known to cause rapid ice melting. For example, at a microwave flux density of 80 kW / m2, exposure for 10 minutes leads to the melting of ice with a thickness of 15 cm (see Microwave heating of asphalt concrete pavements in the journal Science and Technology in the Road Industry, M, publishing house Roads, 1997, No. 2, pp. 28-29).

In FIG. Figures 3 and 4 show the arrangement of the device for microwave exposure to the icicle 20 hanging from the edge of the roof 21. The emitter 8 is mounted close to the icicle using the bracket 18, and the installation can be made both from the ground or from a special vehicle (Fig. 3), and from the roof of the building (Fig. 4). When the microwave generator is turned on, due to the directed radiation of electromagnetic waves, their absorption in an ice dielectric and conversion to heat, the icing melts and collapses.

When repairing bitumen-containing waterproofing coatings of buildings (Fig. 5) using the inventive device, the emitter 8 using the bracket 18 moves along the surface of the coating 22 deposited on the concrete panel 23. When the generator 1 is turned on, the panel heats up and the coating softens to eliminate shells, cracks and evaporation moisture.

Thus, the inventive device has a wide range of functionality that provides effective microwave heating of various dielectric media.

Claims (1)

CLAIM A device for microwave heating of dielectric media, containing a magnetron microwave generator, a transmission line matched to it and an emitter at its end, characterized in that the transmission line is made in the form of a coaxial cable, the beginning of the cable is connected to a coaxial junction, the inner conductor of which is connected to the microwave excitation pin generator, and the outer one with the generator housing, the emitter is made in the form of a segment of a rectangular metal waveguide, one end of which is cut at an angle to a wide wall and closed by a dielectric the other plate is closed with a metal plate perpendicular to the axis of the waveguide, while a hole is made in the wide wall of the waveguide, in the center of which there is an exciting pin at the end of the coaxial cable, and the outer braid of the cable is connected to the waveguide.