RU2351862C1 - Electric furnace for burning of vermiculite concentrates - Google Patents

Abstract

FIELD: heating; construction.

SUBSTANCE: electric furnace for burning of vermiculite concentrates comprises flat pans made of fire-resistant material and installed relative to each other at an angle that provides for raw material pouring in process of burning from one to the other, equipped with electric heaters located on pans surface. Besides pans are equipped with covers with detachable elements fixed at the bottom. At that detachable elements create bulges that form ribbed surface of covers. Electric heaters are arranged in the form of tapes, are installed on rib and under covers on pans surfaces in longitudinal manner so that spaces between neighboring heaters create longitudinal chambers.

EFFECT: increased efficiency with provision of more complete burning and swelling of vermiculite.

3 dwg

Description

The invention relates to the field of building materials, and in particular to technological equipment for the production of expanded vermiculite.

Known furnace for firing vermiculite (RF patent No. 47082, 08/10/2005, B.I. No. 22), made in the form of flat baking sheets of refractory material, installed in relation to each other at an angle that provides the pouring of raw materials in the firing process from one to another, the baking sheets are equipped with electric heaters located on them.

The specified furnace has the following disadvantage. On each of the baking sheets, the movement of vermiculite particles occurs with acceleration, so the particle velocity increases from zero in the upper part of the pan to the maximum value in the lower part. Due to the increase in speed, the particles overcome each subsequent section of the pan with a speed greater than the previous one. But the thermal field created by the temperature radiation of electric heaters is the same in any section of the pan. Consequently, its effect on vermiculite particles due to the ever-increasing speed of their movement in each subsequent section is less effective than in each previous one. Full expansion of vermiculite in it can be achieved only with a stream of vermiculite with a low volume concentration, which limits the productivity of the furnace. With an increase in the volume concentration of particles in the flow, vermiculite particles are more and more thermally insulating (shading) each other and there is not enough time for full firing and expansion. Therefore, many of them, when leaving the furnace, remain under-inflated.

The technical result of the invention is to increase the productivity of the furnace by increasing the concentration of particles in the stream of vermiculite with the provision of its more complete firing and expansion.

The specified technical result is achieved in that the electric furnace for roasting vermiculite concentrates, made in the form of flat baking sheets of piece refractory material (for example, of refractory bricks), installed at an angle to each other, ensuring that the raw material is poured from one to another and equipped with electric heaters located on them, additionally contains covers with removable elements mounted on baking sheets and forming heating modules with them, and electrical heaters in them are made in the form of tapes. The removable elements mounted on the bottom covers are fireproof (heat resistant) and are installed so that each element protrudes above the surface of the cover, and together they form a continuous ribbed bottom surface of the covers, which together with the surfaces of the baking sheets form closed spaces of the heating modules. In the process of particle movement, due to the surface roughness of the piece of refractory material and the joints between them, most of the particles repeatedly bounce off the surface and hit the ribbed bottom surface of the covers. At any given time, in the confined space of the modules, many thousands of particles are simultaneously in a state of jump. Part of the particles, striking against protruding removable elements fixed below the covers and located transversely to the direction of flow of vermiculite, bounce off of them, lose momentum and speed, which leads to a loss of momentum and speed when they collide with other particles, and ultimately , to reduce the flow rate of vermiculite in general. This in turn leads to an increase in the time of movement of vermiculite grains in the temperature field of the heating modules and the duration of firing. Electric heaters, made in the form of ribbons and mounted on a rib, are placed longitudinally under the covers on the surfaces of the baking sheets so that the distance between the heaters and the removable elements of the covers is minimal, and the spaces between adjacent heaters are longitudinal chambers for the movement of vermiculite particles with heaters uniform in height temperature field. Vertical installation of ribbon heaters on the edge provides the same temperature effect on all particles, no matter where in the enclosed space of the module, both on the surface of the pan and in isolation from the surface at the moments of jumps.

Thus, in an electric furnace for firing vermiculite concentrates, due to covers with a ribbed bottom surface formed by removable elements located transversely to the direction of flow of vermiculite, a decrease in the speed of individual particles and the flow rate of vermiculite as a whole, which leads to an increase in the duration of firing and as a result, to full expansion of vermiculite at a higher concentration of particles in the vermiculite stream, and the longitudinal installation on the edge of electric heaters, made in the form of tapes, in which a temperature field uniform in height of the heaters is provided in the chambers formed by adjacent heaters, it allows to increase the concentration of particles in the vermiculite stream and, therefore, to increase the productivity of the furnace.

Figure 1 shows a schematic diagram of an electric furnace for firing vermiculite concentrates, figure 2 shows a longitudinal section of a heating module, figure 3 shows a cross section of a heating module.

An electric furnace for roasting vermiculite concentrates (Fig. 1) consists of a frame 1 and inclined heating modules 2, on the surfaces of which are made of piece refractory material, electric heaters 3 are mounted, fixed with insulators 4. The heating modules are placed on the frame at an angle to each other to a friend for pouring vermiculite in the firing process from one to another and equipped with covers 5.

The heating modules (Fig. 2) consist of baking sheets 6 with surfaces of piece refractory material 7, on which electric heaters 3 are installed in the longitudinal direction, forming firing chambers 8 and covers 5, containing removable elements 9 forming a ribbed bottom surface. Electric heaters 3, made in the form of a ribbon of metal with high electrical resistance, are installed with a step a on the rib, height h (Fig. 3) and placed under the covers 5 on the surfaces of the baking sheets 6 in the longitudinal direction so that the spaces between adjacent heaters 3 are a longitudinal chamber 8 for firing during the movement of particles of vermiculite.

An electric furnace for firing vermiculite concentrates (figure 1) works as follows. When a vermiculite concentrate is supplied (shown by an arrow), its particles under the influence of gravity move along the hot surfaces of the baking sheets in the enclosed spaces of the heating modules 2 and are poured from one module to another. The particles of the concentrate, in the process of movement in the longitudinal firing chambers 8 between adjacent heaters 3 (Fig. 3), are exposed to high-temperature radiation from the surfaces of the heaters, swell and, passing sequentially through the three heating modules, exit the furnace in the form of finished expanded vermiculite (shown by arrow figure 1).

Since the surfaces of the baking sheets 6 (FIG. 2) are laid out of piece refractory material 7, for example, of refractory bricks, during the movement, due to the roughness of their surfaces and the joints between them, most of the particles repeatedly bounce off the surface and hit the surface of the removable elements 9 covers 5. At any moment in the confined space of the heating modules, many thousands of particles are simultaneously in a state of jumping. When the particles hit the surface of the removable elements 9, their momentum (the product of the velocity and the mass of the particle) decreases significantly, and the particle velocity not only decreases numerically, but also changes direction, in some cases to the opposite, hitting neighboring particles and changing their momentum and speed. Thus, the presence of removable elements 9 on the covers 5 ultimately leads to a decrease in the flow rate of vermiculite as a whole, which increases the residence time of vermiculite in the heating modules and leads to an increase in the duration of the firing process.

Due to the increased time spent by particles in the confined spaces of the heating modules and the thickness of the layer of vermiculite flow, the productivity of the furnace increases while maintaining complete dehydration and expansion of vermiculite.

Claims (1)

An electric furnace for roasting vermiculite concentrates, containing flat baking sheets made of refractory material and installed with respect to each other at an angle that feeds the raw material during the firing process from one to another, equipped with electric heaters located on the surface of the baking sheets, characterized in that the baking sheets equipped with lids with removable elements fixed to the bottom, and removable elements form protrusions forming a ribbed surface of the lids, and electric heaters and made in the form of tapes, mounted on a rib and placed longitudinally under the covers on the surfaces of the baking sheets so that the spaces between adjacent heaters form longitudinal chambers.

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