RU2049298C1 - Water-cooled arch of electric arc furnace - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: water-cooled arch of electric arc furnace has coolant supply and discharge headers connected with tubular brackets whose upper and lower branches are located radially and their tops form concentric mounting seat where central part of arch is mounted. Tubular brackets are divided into separate sections; each section is made in form of profiled spring; vertical projection of coils of this spring corresponds to bracket. EFFECT: enhanced service stability of arch. 3 dwg

Description

 The invention relates to metallurgy, specifically to the design of water-cooled arches of melting furnaces.

Known for the arch of an electric arc furnace containing collectors inlet and outlet cooler and connecting tubular elements located radially [1]
The disadvantage of this design is the large number of welds, the tightness of which is often violated due to the large heat load and warpage of the tubular elements. Welding, tube replacement and other repair work require considerable time, which reduces the working time of the furnace and its corresponding productivity.

Known design of the arch, containing collectors of supply and removal of the cooler, connected to tubular brackets, the upper and lower branches of which are located radially, while their vertices form a concentric socket in which the central part of the arch is installed [2]
The disadvantages of this set are the following: a large number of welded sealed joints of the brackets with collectors imposes increased requirements for welded work and implies a greater degree of danger of violation of the sealing of welds and the failure of the set. In case of violation of the sealing of at least one weld, it is necessary to purge the cooling system and weld the resulting crack. This requires a significant amount of time, reduces the operating time of the furnace and thereby its performance.

 The purpose of the invention is to increase the operational stability of the arch and the productivity of the furnace.

 The goal is achieved in that in a water-cooled arch of an electric arc furnace containing cooler supply and exhaust manifolds connected to tubular brackets, the upper and lower branches of which are arranged radially, while their vertices form a concentric landing socket in which the central part of the arch is installed, according to the invention, tubular the arch brackets are divided into separate sections, each of which is made in the form of a profile spring, the vertical projection of the turns of which corresponds to the bracket.

The implementation of the arch in the form of a profile spring significantly reduces the number of sealed welds, and the implementation of the arch section is explained as follows. Upon cooling elements are cooling water is allowed to drain excess temperature above 60 ^{° C,} since it is due to deposition of salts on the inner wall of the pipe, its overgrowth passage section and the output of its failure. Therefore, a significant amount of water must flow through the bracket pipes at a higher speed, which is ensured by excess pressure at the inlet to the cooled element. The implementation of the brackets in the form of a single unbreakable spring leads to a very large hydraulic resistance and, accordingly, to the requirement of a very large inlet pressure. This will require increasing the thickness of the manifold pipe for supplying water and special equipment to increase the pressure of the water. Sectioning the brackets dramatically reduces the hydraulic resistance of the cooling system. In addition, in the case of burnout of the brackets with an unbreakable spring, it will be necessary to purge the entire system, which is also difficult, and with significant burnout and failure of at least one bracket, the entire arch will have to be changed. When dividing the brackets into sections, these shortcomings are eliminated, which has a positive effect on the operational durability of the arch and the productivity of the furnace.

 In FIG. 1 presents the arch, a vertical section; figure 2 is the same, a top view; figure 3 section of the arch, view from below.

 The water-cooled arch of the electric arc furnace contains tubular brackets 1 connected to the inlet collector 2 and the outlet manifold 3. The brackets 1 are open from the side of the working space and are arranged radially with a gap. The brackets 1 are divided into separate sections, each of which is made in the form of a profile spring. The tops of the turns-brackets are interconnected, and the upper branches of the brackets are rigidly connected to the supporting plate 4 of the strips superimposed on them 5. The shell 6 is rigidly connected to the supporting plates 4 of the scarves 7. The central part of the arch 8, made of refractory material, is installed in the seat 9. The vault contains a gas exhaust hole 10.

 The arch is made and works as follows.

 Two guide tubes are mounted vertically rigidly on the turntable. The diameters of the guide tubes are selected in accordance with the required bending radii of the brackets. The distance between the guide tubes determines the dimensions of the brackets. Around the turntable, a special stop is rigidly mounted. A pipe, for example, with a diameter of 76x12, material steel 20, is rigidly fixed at one end on a turntable near one of the guide pipes. Then it is heated, for example, with a gas burner at the bend and the table turns on. The pipe bends with the corresponding bending radius. By sequentially heating and bending the pipes, a spiral of the roof section is wound on the guide pipes. Then the wound section of tubular brackets is removed from the guide tubes of the turntable. The vertices of the turns of the brackets 1 are welded together, and the opposite sides adjacent to the inlet 2 and outlet 3 collectors are wedged around the perimeter of the arch to a predetermined gap, for example, 50-110 mm. On the assembly stand stack the rings of the collectors for supply and removal of the cooler. These rings are the basis of the entire vault and when it is installed on the furnace, they are connected to the suspension of the portal of the mechanism for lifting and turning the vault. A metal shell 6 is installed in the center of the circumference of the collectors at a certain height, which serves to accommodate the central refractory part of the arch 9. The upper collector 3 and the shell 6 are connected by radially mounted support plates 4, which can be made of separate metal sheets, profiles or pipes. Rigidly interconnected collector, shell and plates form a bearing frame of the arch. From below, water-cooled sections 1 are attached to the plates 4 with the help of strips 5, after which the ends of the pipes of each section are connected to the cooler supply and exhaust manifolds. After manufacturing, the arch is pressed, then the sections are made of refractory material.

 The tubular sections of the arch have virtually no welded joints in the hot zone, which increases their reliability and reduces the complexity of manufacturing. The absence of sharp turns of the water flow reduces the hydraulic resistance of the cooling system.

 Between the upper and lower radially arranged pipes, gaps are organized on the collector side. The size of the gaps around the perimeter of the arch is calculated from the condition of reliable retention of the packing and the skull without the use of slag holders, as well as the maximum possible reduction in heat loss during operation of the furnace.

 Reliable retention of the packing and the skull ensures a reduction in heat loss and increases the reliability of the arch, as it reduces the likelihood of burning through the arch when the charge is touched.

 The assembled vault is installed on the furnace and connected by pendants to the portal of the mechanism for lifting and turning the roof of the furnace. The collector 2 is connected to the workshop water supply system, and the collector 3 to the cooler drain system. Before filling the charge into the furnace, the arch is lifted and taken to the side. After filling, the arch turns towards the melting bath and lowers onto the furnace body.

 In case of burn-through of one of the brackets, the section in which it is disconnected from the water supply system and blown with air, after which the pipe is welded at the crack site. With significant destruction of the pipes, the entire section is removed and a new one is installed in its place.

 Since in this design the brackets serve only for cooling the arch and are not load-bearing elements, the resistance of the arch increases. Removing welding spots from the hot zone greatly reduces the chance of arch leakage. Performing a sectional arch allows in case of burn-in of one of the brackets to quickly eliminate the malfunction. All this allows you to significantly increase the durability of the arch and increase the productivity of the furnace.

Claims (1)

 WATER-COOLED ELECTRIC ARC FURNACE, containing cooler supply and exhaust manifolds connected to tubular brackets, the upper and lower branches of which are arranged radially, while their vertices form a concentric seat in which the central part of the arch is installed, characterized in that the tubular brackets are divided into separate sections, each of which is made in the form of a profile spring, the vertical projection of the turns of which corresponds to the bracket.

Images