SU711328A1 - Rotary furnace heat-exchange device - Google Patents

Description

The invention relates to the refractory and building industries, namely, rotary kilns for firing of bulk materials.

A known rotary kiln, comprising a casing, in which metal elements for heat exchange are installed, made of several radially arranged T-shaped parts, and a tube 1 concentric with the drum.

The disadvantages of such a furnace are high pulverization and insignificant heat exchange, since the bulk of hot gases with dust passes along the furnace, without meeting metal elements for heat exchange or material in their way.

The closest in technical essence and the achieved result to the invention is a heat-exchanging device of a rotary kiln containing metallic elements fixed on the inner surface of the housing at equal distances from each other, displaced relative to each other along the generatrix of the housing. Metal elements are made in the form of trapezoid blades attached at an angle of 15-26 both

bases to the inner surface of the furnace 2.

The disadvantage of the known device is an insignificant overhead jHOCTb heat transfer from hot gases to the material, and a sufficiently free passage of hot gases through the cells, something leads to a large gap and reduces the efficiency

heat exchange.

The purpose of the invention is the reduction of dust removal and the intensification of heat transfer.

This goal is achieved by

that in the heat exchange device of the rotary kiln containing metal elements mounted on the inner surface of the housing at equal distances from each other, displaced relative to each other along the forming body, the metal elements are made of channels, facing each other by shelves and connected in the center by a solid plate, placed in a plane, perpendicular to the axis of the furnace, each element being provided with a central part extending along the diameter of the furnace and peripheral parts

a length of 0.3-0.7 central lengths, set at an angle of 150-165 to the central part towards the BtemeHHH furnace, and provided with a divider located on the outer side of each peripheral part facing the rotation of the furnace. In a rotary kiln of this design, hot gases with dust collide with solid plates of metal elements, to that part of the gas flow that passes through the plates, is twisted into the internal space of the elements behind the plates due to vacuum. In this case, the dust is retained by the seams of the seam ler and picked up by the material cast in metal elements. Since the dust remains in the metal elements, there is an intensification of heat exchange between the dust heated to the temperature of hot gases, n. I peresypayu1schms materials. During the operation of the rotating furnace, the material being processed is captured by one of the peripheral parts of the metal element. Upon further rotation of the furnace, the angle of inclination of the peripheral part to the horizon reaches the angle of repose of the material and the material moves to the central part of the element, the angle of inclination of which to the horizon in a given period of time is less than the angle of repose. As a result, material is delayed in the central part of the element, i.e. in the zone of the most intensive heat exchange, for the time between the beginning of the posting of material in the central part from the peripheral part of the element and the moment the central part reaches the angle of inclination equal to the angle of repose of the material. The selected limits of the relative position angles and the ratio of the lengths of the peripheral and central parts of the metal element ensure the maximum delay of the material being processed in the zone of the most intensive heat exchange. If the angle between the peripheral and central parts of the element exceeds 165, or the length of the peripheral part is less than 0.3 of the central part, then the shape of the entire element will approach the direct and material delays in the central part of the element will not occur. if the specified angle is less than 150 °, an overflow will occur, pouring material into the inner space of the element at the junction of the peripheral and central parts and emptying the material from the element, which will increase the dustiness. When the length of the peripheral part is exceeded 0.7, the length of the central part of the element is the relative length of the central part and, consequently, the delay time of the material in it decreases, which will reduce the intensity of heat exchange. The dividers mounted on the outer side of each of the peripheral parts prevent the material from being gripped by the outer side of the element and thereby dusting. The essence of the invention is illustrated in the drawings, in which FIG. 1 shows a rotary kiln, a cross section; in fig. 2 — cold end of the rotary kiln / longitudinal section; in fig. 3 is a cross section of a metal element for heat exchange. A rotary kiln is proposed 1a and comprises a metal body 1 lined with refractory material from the inside. In the cold end of the housing, metallic elements 2 for heat exchange are made of heat-resistant steel. Each element 2 is made in the form of two channels 3, facing each other by shelves and connected in the center by a continuous plate 4, which is installed in the cross-sectional plane of the furnace. Each of the elements 2 comprises a straight central part 5 extending along the diameter of the body 1, as well as two peripheral parts 6 and one connected to the body 1. 7, which are set at an angle with. 150 ° to the central part 5 in the direction of rotation of the furnace. The length of each of the peripheral parts 6 and 7 is 0.5 of the length of the central part 5. The ria to the outer side of each of the peripheral parts 6 and 7, facing the rotation of the furnace, is the divider 8, made in the form of two plates of heat-resistant steel welded under angle to each other. Items 2 are installed at equal distances from each other along the length of the furnace and are displaced relative to each other along the generatrix of the housing 1 in such a way that together they completely overlap the cross section of the furnace housing 1, the rotation of the furnace works as follows, turning the furnace on the processed bulk material gradually moving to the hot end of the furnace. The metal element 2 captures the material with the peripheral part 6, which passes through the layer of material. The divider 8 prevents the material from delaying on the outside of the element 2, and the material is captured only by the internal cavity of the element, formed by the channels 3 and the plate 4. As the furnace rotates further, the angle of the peripheral

part 6 to the horizon, reaches the height of the repose of the material and the material moves to the central part 5 of element 2. In this part, the material is held until it reaches an inclination angle equal to the angle of repose of the material, after which the material from the central part 5 enters into and out of the peripheral portion 7 onto a layer of material in the furnace. The peripheral portion 7 enters the material layer and the process repeats.

During the operation of the furnace, a part of the hot gas flow and dust, moving the degos to the cold end of the furnace, collides with the solid plates 4, and the flow part, the envelope of the channels 3, is closed into the inner space of the element 2 on the reverse side. The dust contained in the stream 3 is contained by the shelves of channels 3 and picked up by the material passing along the elements 2. The cooled- and dust-free gases are removed from the furnace to the heat recovery system and electrostatic precipitators.

The use of the invention makes it possible to increase the productivity of the rotary kiln during the heat treatment of bulk materials, such as magnesite or dolomite, due to a significant reduction in pulverization and intensification of heat exchange. In addition to the intensification of heat transfer, it is possible to improve the quality of firing of the material and reduce the specific fuel consumption compared to the known furnaces. Further, reducing the dust from the furnace makes it possible to reduce the emission of dust into the atmosphere, since the efficiency of the gas cleaning system is greatly increased.

Claims (2)

1. Authors certificate of the USSR. 101603V Cl. F 27 B 7/16, 1952. 2. USSR author's certificate 5 383985, class F 27 B 7/16, 1971 (prototype). Gaze yawning stream - - .J