SU1546503A2 - Cupola furnace - Google Patents

Abstract

The invention relates to devices for heating and thermally treating a metal and can be used in the metallurgical and other industries. The goal is to shorten the annealing cycle, increase the life of the muffle and save fuel. The essence of the invention is that the bell furnace is equipped with additional two pairs of burners mounted on the end walls of the bell, with the burner nozzles located in the center of the walls at a distance of 5.7-6.6 diameters from each other and their axes are directed to the muffle symmetrically the diverging path is m, the angle between the burners is 55-60 °, and the burners are set at an angle of 30-40 ° to the horizontal plane. 2 Il.

Description

The invention relates to devices for heating and thermally treating a metal and can be used in the metallurgical and other industries.

The aim of the invention is to reduce the annealing cycle, increase the life of the muffle and save fuel.

FIG. 1 shows a schematic of an oven; in fig. 2 shows section A-A in FIG. one.

The gas bell furnace consists of a stand 1, a heat-resistant rectangular muffle 2, a metal lined hood 3 forming a working chamber, a hearth made in the form of cast supports 4 under cage 5, between which heat-resistant bottom tubes 6 are laid, connected to the working chamber and located under Bottom injectors 7 for removal of combustion products. The cap 3 is equipped with burners 8 located along its side walls and two pairs of burners 9 located in the center of the end walls at a distance of 5.7-6.6 diameters of gas nozzles from one another and directed to the muffle 2 periphery trajectory m at an angle between them 55-60. The burners 8 and 9 are installed in the cap 3 at an angle of 30-40 to the horizontal plane.

Kolpakova oven works as follows.

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Metal bags are loaded onto the cast legs 4 of the stand 1 of the furnace and covered with a muffle 2. A cap 3 is placed on the muffle 2. Then, air is supplied to the injectors 7 under pressure and a vacuum is created in the bottom pipes 6. Burners 8 and 9 are ignited. Combustion products formed in the area of the burner are raised in the cavity between the muffle 2 and the heating cap 3 and due to the inclined mounting of the burners 8 and 9 provide a uniform flow around the outer walls of the muffle 2. This is also due to the fact that the product jets Combustion emanating from the burners 9, carry out an intensive flow around its end walls. The uniform flushing of the muffle 2 with the combustion products contributes to the identical transfer of heat by convection over its entire surface and, consequently, uniform temperature distribution on the surface of its walls, i.e. to reduce to a minimum the temperature difference along their length and height. Further, the combustion products under the action of the dilution created by the injectors 7 are directed into the bottom tubes 6 and are removed from the working chamber of the furnace, partially giving off the heat of the lower part of the charge 5. Under conditions of fairly uniform flow of the outer surfaces of the muffles 2 into the combustion products 2 It is transferred to the outer surface of the metal cage 5, ensuring its high-quality heating. At the same time, as shown by the results of tests on the aerodynamic model of a bell-type furnace, the uniformity of washing the muffles with combustion products is 2.5–3.0 times higher than that of the existing furnace, which leads to a reduction in the annealing time of the metal. The location on the end walls of the cap of two pairs of burners, the nozzles of which are placed at a distance of 5.7 to 6.6 diameters from one another in the center of the walls and directed to the muffle along symmetrically diverging towards its periphery by trajectories at an angle between them 55-60 ° , allows to provide additional heat supply to the end sections of the packages of the metal charge and thereby reduce the irregularity of its heating to a minimum

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The installation of furnace burners at an angle of 30-40 ° to the horizontal plane significantly improves the uniformity of the flow around the muffle surface with the flow of combustion products, as well as eliminates local overheating in the area of the burner while reducing fuel consumption.

At a distance between the burner nozzles located on the end walls of the cap, less than 5.7 diameters, the peripheral part of the end walls of the muffle is washed by the combustion products worse than the central part, which leads to uneven heating of the muffle and, as a result, the metal charge.

With the distance between the burner nozzles located on the end walls of the cap, more than 6.6 diameters, the central part of the end walls of the muffle is washed with burning products worse than the peripheral part, which also leads to uneven heating of the metal charge.

When the angle between the trajectories of the burner nozzles located on the end walls of the cap is less than 55 °, a local overheating of the surface of the central part of the end walls of the muffle is observed, which is accompanied by a decrease in its operational durability.

When the angle between the trajectories of the burner nozzles located on the end walls of the cap is more than 60 °, a significant part of the combustion products expires directly on the inner surface of the cap, the muffle wall mines, which significantly reduces the efficiency of fuel use in the furnace.

At an inclination angle of the burners to a horizontal plane of less than 30, the combustion products mainly wash the muffle surface in the area adjacent to the burner core, with the result that in the upper part of the charge underheating of the metal takes place and the operational durability of the muffle decreases significantly.

When the angle of inclination of the burners to the horizontal plane is more than 40 °, the combustion products mainly wash the upper part of the muffle, which leads to underheating of the metal in the lower part of the charge.

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FIG. one

Claims (1)

Bell furnace by ed. St. No. 546656, characterized in that, in order to shorten the annealing cycle, increase the service life of the muffle and save fuel, it is equipped with two more pairs of 15 burners mounted on the end walls of the hood, the burner nozzles being located symmetrically relative to the central axis of the furnace at a distance of 5.7-6.6 of their diameters relative to each other, and the axis of the burners are placed symmetrically relative to the longitudinal axis of the furnace at an angle of 55-60 ° to one another and at an angle of 30-40 ° to the horizontal plane.