SI9800119A - Induction heated cell for thermal and chemothermal processing of metals in fluidized bed - Google Patents

Abstract

The construction of an induction heated cell for thermal and chemothermal processing of metals in fluidised bed is described, which consists of a unit for the preparation of the charge (1), a SF generator (2), a mixing battery for gases (3), a SF inductive heated reactor for heating up to the austenitising temperature of 1320 degrees Centigrade or temperatures of chemothermal processing, which is made from steel of W.No. 2.4864 DIN type with a diameter between 150 and 1500 mm (4), an infra-red heated reactor for hardening and releasing in the fluidised bed from steel W. No. 1.4864 with a diameter between 150 and 1500 mm (5), a processor unit for control (6), a reservoir for hardening in oil, polymere solution, salt water etc. (7), an N2 (8) dust undercooling chamber and a bell for the transportation of the charge in protective atmosphere (9). Given are the basic parameters for the production of an induction heated cell for thermal and chemothermal processing of metals in fluidised bed.

Description

INDUCTION HEATED CELL FOR HEAT AND CHEMOTHERMICAL METAL TREATMENT

The subject of the invention is an induction heated cell for thermal and chemothermal treatment of metals in a fluidized bed, which consists of a unit for the preparation of a cartridge, an inductively heated reactor for heating to austenitization temperature of 1320 ° C or temperatures of chemothermal treatments, an infrared heated quenching reactor and a tempering reactor layers, oil hardening tank, polymer solution, salt water and bells to transfer the cartridge in a protective atmosphere.

FIELD OF THE INVENTION

The invention relates to the field of thermal and chemothermal treatment of metals and relates to the use of an induction heated vortex layer for thermal and chemothermal treatment of metals.

A technical problem

The furnaces for thermal and chemothermal treatment of metals in the fluidized bed used today are heated electrically or gas, and the reactor is walled with refractory bricks. For furnaces of this type, the major problem is to reach temperatures above 1200 ° C, which reduces their usefulness. Furnaces with refractory brick construction, which are very sensitive to heat shocks, must be maintained at a temperature of between 600 and 700 ° C, even when they are not in operation, which greatly impairs their energy balance.

In the thermal and chemothermal treatment of metals in the induction-heated fluidized bed, a technique is used whereby, by means of medium frequency (SF) induction, heat is generated in the reacto wall, which is transmitted through convection and radiation to a layer of dry, spaced apart particles. They behave in the same way as a liquid, and the individual particles are microscopically separated by gas motion. Retort made of steel W. Nr. 2.4851 DIN and in which the vortex layer is inductively heated, and by blowing air or gas N _{2 the} conditions for vortex formation are established. By introducing different gases (H ₂ , CO, NH ₃ ...), we create different atmospheres that allow different chemothermal heat treatments to be carried out in the same retort. The use of an induction heated reactor, which is thermally insulated with an inductor-embedded thermo-concrete and an A1 ₂ O _3- based insulation material, enables the swirling layer to be heated rapidly to a temperature of 1320 ° C. Since the thermal insulation of the reacto is no longer used in the construction of refractory bricks, the thermal inertia of the furnace has also been greatly reduced. All this increases its flexibility. However, the energy savings are also greatly increased, the reactor no longer needs to be maintained at temperature, no more heat shock problems.

The state of the art

Typically, thermal or chemothermal treatment of metals is carried out in atmospheric furnaces, salt baths, vacuum furnaces, and in the electrically resisting or gas heated fluidized bed. Both atmospheric furnaces and salt baths are used strictly for specific thermal or thermochemical treatment operations only. The problem with these furnaces is their inflexibility, poor energy efficiency, poor surface of heat treated metal pieces, and the processes themselves are mostly environmentally unfriendly. As a result, in the last decade, the development of these processes has focused on the area of vacuum heat treatment, which is very demanding for investment, and on the refinement of the furnace with a fluidized bed. In the area of the fluidized bed furnace for thermal and chemothermal treatment, the development is driven by the electrically resisting and gas heating of the fluidized bed, but this does not give the fluidized bed furnace sufficient flexibility. For conventional fluidized bed furnaces, reaching temperatures above 1200 ° C is very difficult.

Description of solution to a technical problem with implementation examples

Based on theoretical calculations and assumptions, a SF induction heated cell for thermal and chemothermal treatment of metals in a fluidized bed (hereinafter referred to as the cell) is shown in Figs. 1 is an induction heated semicircle SF cell for the thermal and chemothermal treatment of metals in a fluidized bed according to the invention in orthogonal projection, FIG. 2 SF induction heated cell in a line for thermal and chemothermal treatment of metals in a fluidized bed according to the invention in an orthogonal projection consisting of a cartridge preparation unit (1), a SF generator (2), a gas mixer battery (3), a SF inductive heated reactor for heating to austenitization temperature of 1320 ° C or chemothermal treatment temperature, made of W. W. Nr. 2.4851 DIN (4), Infrared heated tempering and tempering reactor in a fluidized bed of steel W. Nr. 1.4864 DIN (5), Processor control units (6), Oil hardening tanks, polymer solution, brine, etc. (7), N ₂ steam chambers (8), and cartridges to transfer the cartridge in a protective atmosphere ( 9). The cell architecture may be in the form of a semicircle, as shown in the orthogonal projection in FIG. 1, or in the line in FIG. 2. The cell may contain all the above components (complete design) or only the individual 'components required for a specific type of thermal or chemothermal treatment. Transport between individual components in a cell and cell loading is manual, semi-automatic or automatic. The particles swirling in reactor (4) and (5) are from A1 ₂ O ₃ and are larger than 75 pm. Induction heating, we simultaneously exploit the law of induction - the Lenz law and the Joule heat. A water-cooled inductor, through which alternating current flows, produces an alternating magnetic field. According to Lenz's law, a voltage is induced in all electrical conductors located in an alternating magnetic field, which drives the induced currents through that conductor. In their circulation, these induced currents excite Foucault currents, and in the conductor the Joule heat is released. In the given case, the Joule heat is used to heat the reactor wall, the heat is transferred from the reactor wall to a fluidized bed, which by convection and radiation warms the insert to the desired temperature. By choosing the appropriate frequency, in our case between 50 Hz and 50 kHz (NF to SF), we ensure that the inlet depth of the induced currents is limited to the reactor wall. This prevents unwanted uncontrolled heating of the cartridge by induction.

Example

Test cartridge made of test steel for C 55 DIN improvement is prepared on the cartridge preparation unit (1). Using a bell to transfer the cartridge in a protective atmosphere (9), it is embedded in a vortex layer at ambient temperature. In this way, the burned cartridge in a prototype SF inductively heated reactor for heating to austenitization temperature with a working volume of φ 165x590mm (4) is heated at a heating rate of up to 30 ° C / min and more at 835 ° C. The temperature uniformity across the working space of the prototype reactor φ165 x 590mm is ± 5 ° C. The heat transfer coefficient achieved is in a 300 W / m ° C prototype reactor with a fluidized bed. After holding the cartridge at austenitization temperature (approx. 10 min), transfer the cartridge by means of a transfer bell for transferring the cartridge in a protective atmosphere (9) to a tempering tank in oil, polymer solubility, salt water, etc. (7) and cooled to 50-60 ° C in a controlled manner. This is followed by the transfer and loading of the cartridge into an infrared heated reactor for failure in a fluidized bed (5), where it is heated to the temperature of failure. After holding the cartridge at a freezing temperature, transfer the cartridge to transfer the cartridge in a protective atmosphere (9) to the tempering tank in oil, polymer solution, salt water, etc. (7) and cooled to 2530 ° C in a controlled manner.

Test bores and measurements of mechanical and metallographic properties of heat-treated test specimens of steel for C 55 DIN improvement in a prototype cell with a fluidized bed confirm that the prototype SF induction-heated cell for thermal and chemothermal treatment of metals in the fluidized bed successfully satisfies the requirements for thermal and chemothermal treatment of metals (in our case steel to improve C 55 DIN). The test also confirmed the assumption that using a neutral gas (N ₂ with an O ₂ content of less than 10 ppm) that is used to swirl when heated to different tempering temperatures or to remain at the tempering temperature (in our case min at 900 ° C ), offers satisfactory carbon protection. By upgrading the appropriate gas battery and steering, it is possible to achieve all types of atmospheres for chemothermal heat treatment of metals.

Functional testing of SF induction-heated cells for thermal and chemothermal treatment of metals in the fluidized bed confirmed the usefulness and flexibility of the process, the economy of the process in energy as well as in material sense, and the process itself does not pollute the environment.

Claims (1)

PATENT APPLICATION Induction-heated cell for thermal and chemothermal treatment of metals in a fluidized bed, characterized in that it consists of a cartridge preparation unit (1), SF generatoi (2), a gas mixer battery (3), an SF inductively heated reactor for heating to temperature austenitization of 1320 ° C or the temperature of chemothermal treatments made of W. Nr steel. 2.4851 DIN 150 to 1500 mm diameter (4), infrared heated quenching and quenching reactor in a whirlpool steel W. Nr. DIN 1.4864 with diameter 150 to 1500 mm (5), processor units for control (6), oil hardening tank, polymer solution, salt water, etc. (7), chiller chambers in parallels N ₂ (8), and bells for transfer of the cartridge in a protective atmosphere (9).