RU2267868C1 - Flowing inductive liquid heater - Google Patents

Abstract

FIELD: power engineering, possible use in construction of devices for electric heating of liquids.

SUBSTANCE: device has toroidal winding of inducer, applied to core, consisting of steel tubular coil pipe with applied winding of steel band. Magnetic duct, product duct and heating element of heater are combined, and core realizes their functions. To decrease specific metal consumption down to 2-2,5 kg/kWt during operation of inductive heater strong magnetic fields are used with strength 25-40 kA/m. coil pipe has coils of similar radius, and winding of steel band is tightly pressed to whole external surface of coil pipe, so that all ferromagnetic substance takes part in heat exhaustion, electric resistance of heater is decreased, and, as a result, its metal consumption. To prevent steel corrosion and to heat food liquids, thin-walled insert is used made of stainless steel, positioned in coil pipe tube. To improve heat exhaustion from heater core to liquid flowing along coil pipe, wire spiral is used of stainless steel, which is inserted into coil pipe tube, and is used to provide additional circulation of liquid.

EFFECT: higher efficiency.

3 cl, 2 dwg

Description

The invention relates to the electric power industry and can be used in devices for electric heating of liquids for livestock buildings, production workshops, liquid food processing enterprises, in the service sector, and in everyday life.

Known induction fluid heater (Yarovikov I.P. Calculation of induction heaters for livestock buildings // Mechanization and Electrification of Agriculture, No. 4, 1983) for heating floors and air in rooms, the casing of which contains steel water and gas pipes, inside of which a multicore winding of insulated wire. The principle of operation of the heater is that when the alternating current flows and due to the alternating magnetic field created by it, the pipe material is heated due to hysteresis and eddy current losses.

Also known is a flowing liquid water heater (Pat. 2101882 RF, IPC 7 N 05 V 6/10, F 24 H 1/10. Transformer type electric water heater / V.M. Kuzmin, A.V. Serikov, S.P. Bobrovsky / / Discoveries. Inventions. 1988. No. 1), which is a three-phase transformer-heater, the secondary windings of which are short-circuited and made of three steel pipes. The ends of the pipes are interconnected by electrically conductive disks, forming together with the outer shell of the transformer a sealed chamber, inside of which an inductor is located. Water, washing the transformer shell and passing through the pipes, heats up.

The closest (prototype) is a fluid flow heater (US 3414698 (GENERAL ELECTRIC COM) 03/03/1968), which is a multilayer tubular coil on which a toroidal coil of the inductor is superimposed. The water passing through the coil heats up. A disadvantage of the known devices is the large specific metal consumption (up to 10 and more kg / kW), significant scattering of magnetic fluxes and, as a consequence, large heat loss.

The aim of the invention is to reduce metal consumption, increase efficiency and reduce structural complexity. This goal is achieved by the fact that the proposed flow-through induction fluid heater 1) combines a magnetic circuit, a heating element and a product pipeline, the function of which is made from a steel pipe coil with tight-fitting coils with a winding superimposed on it from several layers of steel tape; 2) a region of strong magnetic fields with an intensity of 25-40 kA / m is used; 3) the turns of the coil are made of the same radius, as a result of which the entire volume of the ferromagnet is involved in the heat release; 4) a winding made of steel tape fits snugly to the entire outer surface of the coil, which reduces the electrical resistance of the heater.

A flow-through induction fluid heater is shown in FIG. 1 with a section along section AA — in FIG. 2. The heater consists of the winding of the inductor 1 and the core, which is a tubular coil 3 with a winding made of steel tape 2 attached to it. The coil is made with the same radius of turns from a steel pipe. The winding of steel tape is attracted to the surface of the coil using a spiral wire clamp 4, which is laid between the turns of the coil. A thin-walled liner 5 and a wire spiral 6 made of stainless steel are placed inside the coil pipe. The heater has a primary winding (inductor winding) made of insulated copper wire; the role of the secondary winding is played by a winding of steel tape and the wall of the steel pipe of the coil. Adjacent coil coils fit snugly together. A coil of steel tape of such a thickness is applied to the coil so that an electromagnetic wave reflected from the inner walls of the pipe does not adversely affect the power factor. A toroidal winding of the inductor is superimposed on this core, which makes it possible to concentrate the magnetic flux inside the toroid. As a result, scattering fluxes are significantly reduced and there is no negative impact of strong fields on staff. To prevent corrosion of the inner walls of the pipe, a thin-walled stainless steel liner tightly adjacent to the inner walls is placed in it. To increase the heat transfer coefficient and thermal efficiency, a stainless steel wire spiral is introduced into the pipe lumen, which leads to additional fluid circulation.

Such a constructive solution allows to reduce the metal consumption of the heater to 2-2.5 kg / kW and increase thermal efficiency to 98-99%.

According to the information available to the authors, the set of essential features guaranteeing the essence of the claimed invention is not known and it should not be obvious to the experts from the prior art that will allow us to conclude that the invention meets the criteria of "novelty" and "inventive step".

Flow induction fluid heater operates as follows. An alternating voltage is applied to the primary winding (inductor winding). The alternating magnetic flux created by the winding is closed in the heater core, consisting of a tubular coil and a winding superimposed on it from several layers of steel tape of such a thickness that a reflected electromagnetic wave does not occur, reducing the power factor of the heater. An alternating magnetic flux generates an induction current in the core, as a result of the passage of which the core is heated. Additional heating occurs as a result of magnetization reversal of the core material (hysteresis loss).

The winding of steel tape is tightly drawn to the surface of the coil with a spiral wire clamp, laid between the turns of the coil. The need for a snug fit of a winding of steel tape to the entire outer surface of the coil made of steel pipe is explained by the fact that the direction of the induction currents in adjacent turns in the area of their contact is opposite. This makes their passage difficult, as a result of which induction currents are closed through the winding layer of steel tape. If there is an air gap between the winding of the steel strip and the point of contact of adjacent turns of the coil, the induction current will pass in the area where the tape is adjacent to the turns of the coil, inside the winding of steel tape and inside the pipe of the coil, and in the area where the air gap is only inside steel tape windings. This increases the electrical resistance of the heater and, as a consequence, its metal consumption.

To prevent corrosion of steel and to be able to use a device for heating food liquids, a thin-walled stainless steel insert is placed inside the coil pipe. The core heats up and transfers heat to the fluid flowing through the coil. To improve heat transfer, a stainless steel wire spiral tightly adjacent to the inner wall is placed in the pipe lumen, which causes additional fluid circulation. The core of the heater performs the function of a magnetic circuit, a heating element and a product pipeline at the same time.

The advantage of the proposed induction fluid heater is as follows:

- small scattering of the magnetic flux, therefore, a higher efficiency and the absence of negative effects of strong magnetic fields on the body of people in the vicinity;

- due to the same radius of the coil turns and tight fit of the winding made of steel tape to the entire outer surface of the coil, the entire volume of the ferromagnet is involved in heat generation, which significantly reduces the metal consumption of the heater;

- the specific metal consumption decreases to 2-2.5 kg / kW as a result of combining the magnetic circuit, product pipeline and heating element and through the use of strong magnetic fields with a strength of 25-40 kA / m;

- high heat transfer from the core of the heater fluid flowing through the coil as a result of additional fluid circulation caused by a wire spiral placed in the lumen of the coil pipe;

- the absence of corrosion of steel and the possibility of heating and pasteurization of food liquids (water, juice, milk, etc.) as a result of using a stainless steel insert in the coil.

Claims (3)

1. Flowing induction fluid heater having a toroidal coil of an inductor superimposed on a core consisting of a steel tubular coil, characterized in that it uses a tubular coil with the same radius of tightly adjacent turns; a winding made of steel tape is laid on the coil tightly adjacent to the outer surface of the coil; To improve the heat transfer from the heater core of the fluid flowing along the coil, a wire spiral is used, introduced into the lumen of the coil pipe, leading to additional fluid circulation. 2. Flowing induction fluid heater according to claim 1, characterized in that in order to reduce its specific metal consumption to 2-2.5 kg / kW during operation, magnetic fields with a strength of 25-40 kA / m are used. 3. Flowing induction fluid heater according to claim 1, characterized in that it uses a thin-walled stainless steel insert placed in the coil pipe to prevent corrosion of steel and to heat food liquids.

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