SU854901A1 - Electric furnace for thermal treatment of high-fusible oxide material articles - Google Patents

Description

I

The invention relates to industrial building materials, in particular, equipment for the production of optical glass.

A high-temperature electric furnace is known with an oxide high-temperature heater made in the form of a vertically installed pipe with thickenings on the walls | .

The disadvantage of this furnace is low reliability and performance, as a result of the design features of the electric heater and the method of its installation in the furnace. At high temperatures, the tubular heater is deformed by its own weight, since the materials used for its manufacture, such as modified oxides of zirconium and hafnium, are characterized by a large specific gravity. Therefore, the weight of the upper thickened output of the electric heater. The body exceeds the maximum permissible mechanical load, by more

thin-walled central high-temperature part of the electric heater. In addition, GO; - not using the internal volume of the tubular electric heater as the hot space of the furnace, taking into account the specifics of the materials used, does not significantly increase the working chamber.

The closest technical solution to the invention

to the essence and the achieved result is an electric furnace dp of heat treatment of products from refractory materials, including a chamber, an oxide heater, made in the form of

IS constituting the working capacity of bodies with a flat radiating surface, electrodes, a starter trigger, and a thermal insulating housing | 2J.

The disadvantage of this design

I electric furnace is low productivity because the performance of high-temperature electric furnace depended on the working chamber.

which is determined by the dimensions of the heater. Increasing the size of the prefab to increase the performance of a known furnace leads to the desire of the heater, and consequently, to an increase in the forces holding it, which even more lowers the reliability of the furnace.

The purpose of the invention is to increase its reliability and performance.

The goal is achieved by the fact that the electric furnace for heat treatment of products made of refractory oxide materials, including a chamber, an oxide heater, made in the form of a working capacitive body with a flat radiating surface, electrodes, starting heater and heat insulating body, is equipped with movable supports for the oxide heater, placed on the bottom of the camera. .

C. The purpose of creating a temperature gradient inside the working tank is to provide autonomous regulators for the electrical supply of each body to an oxide heater separately,

And in order to create a temperature gradient inside the working tank with one electric power regulator and a series electrical connection of the oxide body heater bodies, the structure is made of oxide material with different electrical resistance.

The performance of this furnace is increased by increasing the dimensions of the heater, without reducing the reliability.

Testing an experimental model of a furnace with a working capacity of l, 5vlO cm%, made in accordance with the proposed technical solution, shows that after it has been continuously operating for several tens of hours at a temperature in the working capacity, the electric heater and the current-circulating solar cells are in good condition, whereas in the known construction, the contacting parts of the high-temperature heater and the current-carrying electrodes are usually destroyed. Thus, the use of movable supports in the proposed design provides increased reliability and productivity of the furnace. The specified supports are used to reduce frictional forces between the high temperature heater, the movable supports and the bottom lining.

it is advisable to perform, for example, in the form of rollers. .

FIG. 1 shows a schematic of an oven, section A-A in FIG. 2; Fig.2to same, section BB in Fig.1.

In the central part of the furnace is a resistive oxide heater, made in the form of two parallel mounted on the edge

plates 1 and 2 of zirconium dioxide modified with complex additions of calcium magnesium oxides and yttry in the amount of 13 mol%. In the kiln that was tested, the length of the plate was 235 mm, width 115 mm, thickness 25 mm. The figured cuts on the side of the plate, facing outward from the working chamber, reduce the effective cross-section of the plate by half compared with the area of the ends. and increase its bending stiffness. To improve contact with electrodes}, the ends of zirconia plates are impregnated with an electrically conductive composition based on yttrium chromite and monovalent copper chromite. The distance in the furnace between the planes of the plates is 110 mm. To the ends of the plates, which are current-carrying

Claims (1)

0 part of the electric heater, the electrodes 3, pryukaty, made in the form of plates with a thickness of 15 mm and an area of 25x115 mm from solid solutions of yttrium chromite and chromite monovalent copper. The electrodes 3 are pressed to the heater by moving in a horizontal direction water-cooled metal refrigerators 4 connected to a pressure spring mechanism 5, which is located outside of the furnace body 6. The plates 1 and 2 lower edge are supported each by two moving supports 7, made in the form of rollers 10 mm and a length of 30 mm from a material similar to the material of electric heaters. The supports are located 1/4 the length of the heater to the center from its ends and lie on the bottom high-temperature lining 8 made of calcium zirconate in the form of two monolithic blocks separated by an air gap of 5 mm and bar 9 of magnesium oxide. Top and sides of the heater it is protected by a high-temperature lining based on calcium zirconate, which does not have direct contact with the heater plates. The inner space of the working container from the side of refrigerators and electrodes is protected by inserts 10, made in the form of rectangular blocks of zirconium oxide, which rest on the bottom lining and do not come into contact with the electric heater plates. The start-up electric heater is made in the form of two sections of siliconizer heaters 11 connected in parallel, which are located on the side, the surface of the plate between the lined heat-insulating furnace body and the high-temperature lining surrounding the high-temperature oxide heater on the side of the plates. The metal structure of the furnace 6 and the lightweight heat insulating lining 12 is a layer of kaolin wool 13 with a thickness of 40 mm. The proposed furnace model has the external dimensions of a lined case mm, the dimensions of the working capacity are 100x100x150 mm. The power of silicon heaters is 16 k; W. The output power of the oxide electric heater is at a temperature in the working chamber of 2000 ± 25 ° С 12.6 kW. The furnace works as follows. The starting electric heater is turned on and, by adjusting the electrical power, the oxide heater is heated to a speed of up to 5 K / min. At this temperature, the oxide heater material becomes sufficiently conductive. After preheating, electrodes 3 are supplied with electric power of the industrial frequency with an adjustable current. When electric current passes through the heater, it is heated to the required temperature. In the process of heating, it is necessary that the rate of temperature change in the working capacity of the furnace does not exceed 5 deg / min, in order to avoid damaging internal mechanical stresses due to uneven heating, Starting heaters are turned off at the moment of self-heating of the high-temperature oxide electric heater. In addition, they can be used as a heat supply to increase the efficiency of heating the working chamber at low currents of oxide electric heaters. The furnace shutdown is carried out in the reverse sequence Dp in order to create a temperature 016 gradient with one power regulator and the series connection of the heater plates (bodies), the plates {body are made of oxide material with different electrical characteristics. The need to develop furnaces with a temperature gradient can be associated, for example, with growing crystals from melts of refractory materials or as a result of recrystallization. When processing low-temperature materials, one-sided heating of the furnace can be used. However, a DNP of refractory materials with a small constant temperature gradient in a one-way heating furnace is not enough. The use of a heater made in the form of two bodies forming a working chamber with independent temperature control to a lesser extent guarantees the stability of the furnace temperature difference than the use of a heater made in the form of two bodies of material with different electrical resistance connected in series to one power source. Increased productivity is associated not only with an increase in the working chamber, but also with an increase in the reliability of the furnace, which leads to a reduction in the time for its maintenance, repair and replacement of the previously used elements, and provides significant savings due to the long-term use of expensive products made of scarce materials. . Thus, as can be seen from the comparative test results, the design of the furnace increases its reliability and performance, increasing the reliability of the furnace makes it possible to expect an annual economic effect only by reducing the consumption of high-temperature sour electric heaters and electrode materials during the operation of one furnace for a year at least 12 -Rub, Claim 1. The electric furnace for heat treatment of the refractory oxide materials, including the chamber, oxide heater, made in the form Referring working capacity zluchayuschey bodies with the flat surface electrodes.