EA015523B1 - Device for microwave heating of liquid dielectric mediums - Google Patents

Abstract

The invention relates to microwave equipment and can be used for heating of various liquid dielectric mediums, including warming up of stiff oil products, extracting viscous oil and natural bitumens in situ. The device comprises microwave generator, matched transmission line and radiator, wherein the transmission line is made in the form of coaxial cable in the end of which the radiator in the form of asymmetrical vibrator with coaxial dielectric case is fixed; sending end of the cable is connected with a coaxial transducer, the internal conductor thereof is connected to a feed probe of the microwave generator, and the external conductor - with the generator frame. The flexible coaxial cable with the radiator on the end ensures functioning of the device at a significant depth, and the protective dielectric case allows to work in liquid medium. The coaxial transducer provides the matching of the generator with the cable. The asymmetrical vibrator with the sizes chosen according to the frequency of the generator and dielectric parameters of the medium, is the radiator connected with the medium, so it provides radiation of all input electromagnetic energy.

Description

(57) The invention relates to microwave technology and can be used to heat various dielectric media, including when heating frozen petroleum products, when producing viscous oils and natural bitumen in their places. The device contains a microwave generator, a transmission line and a radiator matched with it, characterized in that the transmission line is made in the form of a coaxial cable, at the end of which a radiator is mounted on its inner conductor in the form of an asymmetric vibrator matched to the medium with a coaxial dielectric casing, the beginning of the cable is connected with a coaxial junction, the inner conductor of which is connected to the exciting pin of the microwave generator, and the outer one to the generator housing. A flexible coaxial cable with a radiator at the end allows the device to work at a considerable depth, and the protective dielectric skin x allows you to work in a liquid environment. A coaxial junction ensures that the generator matches the cable. An asymmetric vibrator with dimensions selected in accordance with the frequency of the generator and the dielectric parameters of the medium is a radiator consistent with the medium and thereby provides radiation of all the electromagnetic energy supplied to it.

015523 B1

The invention relates to microwave technology and can be used for heating various dielectric media, including when heating frozen petroleum products, as well as in the production of viscous oils and natural bitumen in their places.

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 medium being processed - bitumen pavement (RF patent No. 2039145, 1993), liquids (RF patent No. 2087083, 1997 g) or petroleum products in the tank (RF patent No. 2224387, 2004). The disadvantage of these devices is the limited depth of heating of the medium, due to the fact that the emitter is located above its surface.

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 microwave generator (for example, magnetron) connected to it by a rigid waveguide line transmission and horn emitter located above the surface of the oily medium. With this arrangement of the emitter and the fixed operating frequency of the generator, the penetration depth of electromagnetic waves into the medium is determined by its dielectric constant and the dielectric loss tangent and, therefore, does not depend on the characteristics of the device. As a result of this, microwave heating of the medium occurs only in its near-surface layer; considerable time is required for heating the deep layers, which is a disadvantage of the device. Another disadvantage is that due to reflections of the electromagnetic wave from the boundary of the medium and side radiation, the microwave energy does not completely transfer to the dielectric medium through the gap between the radiator and the boundary. Thus, the efficiency of the device (i.e., the conversion of microwave energy into heat) could be higher if the microwave energy completely transferred to the medium.

The technical problem solved in the present invention is the possibility of microwave heating in the depth (i.e. in volume, and not on the surface) of the dielectric medium, which ensures maximum efficiency of the device. The problem is solved in that in the known device containing a microwave generator, a transmission line and a radiator matched with it, the transmission line is made in the form of a coaxial cable, at the end of which a radiator is mounted on its inner conductor in the form of an asymmetric vibrator matched to the medium with a coaxial dielectric casing, 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 to the generator housing.

A flexible coaxial cable with a radiator at the end ensures the operation of the device at a considerable depth, and a protective dielectric casing allows you to work in a liquid medium, which is an advantage of the claimed device compared to the prototype. A coaxial junction ensures that the generator matches the cable. An asymmetric vibrator with dimensions selected in accordance with the frequency of the generator and the dielectric parameters of the medium is a radiator consistent with the medium and thereby provides radiation of all the electromagnetic energy supplied to it.

In FIG. 1 shows a diagram of a device; in FIG. 2 - its location when working in a liquid medium; in FIG. 3 - location when working in a well in a solid medium; in FIG. 4 - dependence of temperature in an oil-containing medium on the time of microwave exposure, measured during operation of the device’s layout.

The device (Fig. 1) contains a microwave generator (for example, a magnetron) 1 with an exciting pin 2, which is connected to the inner conductor of the coaxial transition 3, which serves to coordinate the generator with the coaxial cable 4. The flange 5 of the coaxial transition is mounted on the generator body. For ease of operation of the device, when replacing the generator or cable, there is a coaxial connector 6 fixed at the end of the coaxial transition, while its inner conductor 7 is connected to the inner conductor of the coaxial connector. At the end of the coaxial cable, an emitter in the form of an asymmetric vibrator is formed on its inner conductor, formed by the outer conductor of the coaxial 8 and the nozzle 9, connected to the inner conductor of the coaxial and separated from the outer conductor by an insulating washer 10. To protect the emitter from exposure to a processed medium, such as liquid petroleum products, serves as a coaxial dielectric casing 11.

To match the emitter with the medium, the length of the nozzle of an asymmetric vibrator should be a quarter of the length of the electromagnetic wave in the medium, which depends on the dielectric parameters of the medium and the frequency of the generator. For example, the dielectric constant of solid oil-bearing rocks lie in the range of 2-4 (see, for example, Revizsky Yu.V., Dyblenko VP Research and justification of the oil recovery mechanism using physical methods, Chap. 4. M., “ Non-Business Center ”, 2002). Therefore, when the frequency of the microwave generator is 2450 MHz, allocated according to the current “Table of the distribution of radio frequency bands”, approved by the RF State Commission for Radio Frequencies for industrial and domestic use, the nozzle length should be 15-20 mm.

The location of the device for microwave heating of the medium depends on its nature.

For example, for a viscous thick medium 12 in the tank 13 (Fig. 2), the cable 4 with the emitter 9 and the casing 11 at the end is immersed in the medium to the required depth, which can increase as the medium warms up.

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For dense oil-bearing rocks 14 (Fig. 3), in which oil is produced through various wells, including vertical and inclined sections 15, a flexible cable 4 can be introduced into the well so that the emitter is in the desired oil-containing layer 16. When using modern coaxial cables, the immersion depth of the emitter can be several tens of meters.

When working in oily solid rocks, the device provides fast and efficient microwave heating. This is confirmed by the test results of the device layout in a sample of oily sandstone. In FIG. Figure 4 shows the temperature dependence of the time of microwave exposure at a distance of 0.2 m from the emitter at a generator power of 600 W and a frequency of 2450 MHz. The rate of heating the rock was up to 10 deg / min, and oil evolution began after a 5-minute exposure, since at a temperature of 50 ° C the viscosity of the oil decreases tenfold (see, for example, Ruzin L.M., Chuprov I.F. Technological principles for the development of deposits of abnormally viscous oils and bitumen, Chapter 1. Ukhta, USTU, 2007)

Claims (1)

A device for microwave heating of dielectric media containing a microwave generator, a transmission line and an emitter, characterized in that the transmission line is made in the form of a coaxial cable immersed in the medium, at the end of which an emitter is mounted on its inner conductor in the form of an asymmetric vibrator with coaxial dielectric casing, the beginning of the cable is connected to a coaxial junction, the inner conductor of which is connected to the excitation pin of the microwave generator, and the outer one is connected to the generator housing.