RU2301507C2 - Inductive-conductive liquid heater - Google Patents

Abstract

FIELD: electric engineering, possible use for heating technological liquids, and also heat carrier for electric heating and drinking water.

SUBSTANCE: inductive-conductive liquid heater contains transformer with ferromagnetic core with primary winding and secondary winding positioned on rods, secondary winding being the heating chamber, made hollow with input and output branch pipes for passage of liquid being heated, in which through channels are present with electro-conductive walls, in each one of which with a gap a transformer core rod is mounted, while heating chamber is divided on identical parts based on number of transformer core rods, while aforementioned input and output branch pipes and through channel with transformer core rod mounted in it are positioned on each side of heating chamber.

EFFECT: decreased material costs, increased heat productivity, even electric phase load and improved energy characteristics (efficiency and cosφ), and also even movement of liquid stream, lowering amount of salt precipitation on well walls and increasing lifetime, expanded functional capabilities of heater due to simultaneous heating of two or more liquids.

2 cl, 1 dwg

Description

The invention relates to electrical engineering and can be used to heat process fluids, as well as a coolant for electric heating and drinking water.

Induction fluid heaters have been known for a long time, for example, “a vessel that uses the iron core of a transformer for inductive conductive heating of a liquid” (German patent No. 329131 with priority dated January 22, 1918), which has not received practical application due to the large specific material consumption and low coefficient conversion of electricity into heat (efficiency) and power factor (cosφ).

However, the indisputable advantages of low-frequency (50, 60 Hz) induction fluid heaters in relation to modern requirements of electrical safety and fire safety in comparison with resistive heaters (heating elements) and electrode (for water) have led to increased interest in new designs of induction heaters. These include, for example, an inductive-conductive electric fluid heater (according to the application of France No. 2565059, MKI Н05В 6/10), which makes it possible to use the design and manufacturing technology of traditional three-phase transformers containing a lined core with a primary winding connected to the network and a secondary winding made in the form of a short-circuited coil of electrically conductive tubes in which there is a liquid heated due to heating losses from short-circuit currents of the secondary winding.

The disadvantages of this electric heater include a limited power factor due to the increased magnetic flux scattering associated with a multi-turn secondary winding; uneven heating of the electrically conductive tubes over the cross section, leading to local overheating and steady vaporization, causing intense salt deposition, and a decrease in the cross section of the pipeline; increased hydrodynamic resistance of the heating tubes of the coil and increased power losses on the fluid circulation.

Known inductive conductive fluid heater with an improved power factor (US patent No. 4602140, MKI N05B 6/10, NKI 219-10.51), containing a transformer with a multi-rod ferromagnetic core, the rods of which are wound primary winding connected to an alternating current network. The secondary winding, inductively connected to the primary winding through the core, is a single-turn system of straight tubes of electrically conductive material extending outside the core rods perpendicular to them and parallel to the turns of the primary winding, and electrically conductive non-magnetic plates electrically closed at the ends. This system of tubes heated by induction currents is a heat exchanger (heating chamber) in which the coolant is heated.

The disadvantages of this heater include a small heat transfer surface, which causes increased specific surface heat loads, causing scale formation in the tubes, and increased energy loss on the coolant circulation.

The closest in technical essence to the proposed one is the inductive-conductive fluid heater adopted as a prototype (certificate for utility model RU No. 21709 U1, 7 Н05В 6/10), containing a transformer with a ferromagnetic core with a primary winding and a secondary winding located on the rods, which is a chamber heating up. The heating chamber is made hollow with inlet and outlet nozzles for passing a heated fluid, in which there are through channels with electrically conductive walls, each of which has a transformer rod with a gap. The heating chamber is equipped with jumpers forming closed electrically conductive circuits.

The disadvantages of the prototype include:

increased material consumption due to the large surface of the shell of the heating chamber, made of electrically conductive material and covering all the rods of the transformer;

uneven heat release in the walls of the heating chamber due to the different current density in the walls of the chamber, leading to a decrease in the heat output of the device;

uneven electrical load of the phases of the device due to electrical asymmetry of the heating chamber, causing a decrease in energy indicators (efficiency and cos φ) of the entire heater;

non-uniform movement of the fluid flow, which contributes to overheating of the peripheral zones of the heating chamber and enhancing salt deposits on the walls of the chamber, i.e. decrease in service life;

limited functionality, as simultaneous heating of two or more liquids is excluded.

The objective of the invention is the creation of an inductive conductive fluid heater with reduced material consumption, increased heat output, increased energy performance (efficiency and cos φ), increased service life, extended functionality.

This object is achieved in that in an inductive-conductive heater, which contains a transformer with a ferromagnetic core and primary winding and secondary winding located on the rods, which is a heating chamber, made hollow with inlet and outlet nozzles for the heated fluid, in which there are through channels with electrically conductive the walls, in each of which a transformer rod is installed, the heating chamber is divided into identical parts according to the number of transformer rods, and these the inlet and outlet pipes and the through channel with the transformer rod installed in it are located in each part of the heating chamber.

Also, each part of the heating chamber can be equipped with electrically conductive closed circuits installed inside it.

The drawing shows the proposed inductive-conductive fluid heater using an example of a three-phase transformer, which contains a lined ferromagnetic core 1 with primary winding 1 located on the core rods connected to the network.

The secondary winding of the transformer is a heating chamber, which is made in the form of three (according to the number of core rods) cylindrical hollow parts 3 with input 4 and output 5 pipes for the passage of the heated fluid, each part has a through vertical channel 6 with electrically conductive walls 7, in which with a gap core rod 1 is installed. Between the surfaces of the walls 7 and the primary winding 2 there are air gaps.

Each part 3 is made of sheet material, while the cylindrical electrically conductive walls 7 of the through channels 6, the lower 8 and upper 9 end bases, forming integrity and impermeability to the heated fluid of the volume of the chamber part 3 (for example, by welding), can be made of different thicknesses and from different materials.

Each part 3 of the heating chamber can be provided with closed conductive circuits of various sizes and shapes, for example in the form of a cylinder 10 installed inside each part 3.

Inductive conductive fluid heater operates as follows. After filling the parts 3 of the chamber with a heated fluid, the primary winding 2 is connected to an AC network and magnetic fluxes are created in the rods of the core 1 of the transformer. Under the influence of these flows (time-varying) in the walls 7 of the channels 6, as well as the circuits formed by the cylinders 10, currents are induced, causing heating of the parts 3 of the chamber. In the lower 8 and upper 9 bases of parts 3 of the chamber, a system of secondary currents is induced, which causes additional heat generation and corresponding heating (bottom and top) of the liquid in parts 3 of the chamber.

The technical effect of the proposed inductive-conductive electric fluid heater in comparison with the prototype is as follows:

the material consumption of the inductive-conductive heater is reduced due to a decrease in the outer surface of the heating chamber;

uniform heat dissipation is provided in the walls of the heating chamber in connection with ensuring equal current density in the walls of the chamber due to the cylindrical design of each part of the heating chamber, leading to an increase in the heat output of the device;

a uniform electrical load of the phases of the device is ensured due to the electrical symmetry of each part of the heating chamber relative to the phases of the supply voltage, which increases the energy performance (efficiency and cos φ) of the entire heater as a whole;

uniform movement of the fluid flow in each part of the heating chamber is ensured in connection with the provision of the same hydrodynamic resistance in different sections of the fluid flow, leading to a constant velocity of the fluid flow, which reduces salt deposits on the walls of the chamber and increases the service life;

expand the functionality of the heater due to the simultaneous heating of two or more liquids.

Claims (2)

1. Inductive conductive fluid heater containing a transformer with a ferromagnetic core located on the core rods of the primary winding and the secondary winding, which is a heating chamber, made hollow with inlet and outlet pipes for the passage of the heated fluid, in which there are through channels with electrically conductive walls, each of which a transformer core rod is installed with a gap, characterized in that the heating chamber is divided into identical parts according to the number of core rods chnika transformer, said inlet and outlet and a through channel with the rod mounted therein transformer core disposed in each portion of the heating chamber. 2. The inductive-conductive fluid heater according to claim 1, characterized in that each part of the heating chamber is equipped with electrically conductive closed circuits installed inside it.