RU2224195C2 - Shaft-type heat exchanger for rotary furnace - Google Patents

Abstract

FIELD: metallurgy; heat treatment of material before loading it to rotary surface. SUBSTANCE: proposed device has profiled shaft, solid walls, or solid and shutter-type walls, ceilings, loading and unloading units, heat- transfer agent supply cavities located above slope of repose of material and heat-transfer agent discharge cavities; at least one heat-transfer agent discharge cavity is formed by ceiling and solid wall and is located above slope of repose of material and heat-transfer agent discharge cavities are arranged in at least two vertical tiers. Housing of heat exchanger may be made in form of two trapezoidal members with common base; at least one discharge cavity is formed by ceiling, shutter-type wall and solid walls; heat-transfer agent supply and discharge cavities are located in staggered order by tiers; at least one heat-transfer agent supply cavity is provided with burner units for autonomous heating. EFFECT: enhanced operational reliability. 5 cl, 2 dwg

Description

 The invention relates to devices for heat treatment of material (lump, granular, briquetted or mixtures thereof) before loading it into a rotary kiln.

 Known shaft heat exchanger rotary kiln for heat treatment of granular and granular material, containing a vertical shaft, movable walls such as louvers, made on the selection side of the coolant, solid walls, the inlet and outlet of the coolant with uneven bottoms, loading and unloading devices, while the distribution channels of the duct the coolant supply are located above the slope of the material (Patent application RU 95116896/03 with priority from 10/04/95, F 27 D 1/00, B. "Inventions", 1997, 30, part 1, p. 115, publ. 10/27/97).

 In this heat exchanger, the coolant at all levels of its supply to the material layer enters from one side along the material, which leads to heterogeneity of the heat treatment of the material along the width of the layer. The execution of the heat exchanger single-branch along the material increases its main limiting dimensions, either the length of the supply and removal chambers of the heat carrier, or the height of the heat exchanger due to the need to organize a large number of tiers, and ultimately limits the amount of flue gases that can be passed through the heat exchanger. In addition, the heat exchanger casing is made rectangular, which leads to the need to install several pushers - unloaders in the unloading unit for the length of the supply and removal chambers corresponding to practical needs.

 Also known is a rotary kiln shaft heat exchanger for heat treatment of lump, granular or briquetted material, containing a vertical shaft, blinds-type walls made on the side of the heat carrier, the coolant supply cavity located above the level of natural slope of the material along the tiers of the heat exchanger in a checkerboard pattern, and the cavity heat transfer fluid, including the central cavity formed by two louvered walls. The shaft heat exchanger is made of a two-branch, with a trapezoidal body, a central cavity of the heat carrier in the form of a "Christmas tree". Its coolant supply cavity and / or unloading unit are equipped with burner devices (Patent RU 2145696 C1, publ. 02.20.2000, F 27 V 7/34).

 The louvre walls that form the central cavity of this heat exchanger are a complex metal structure operating in severe temperature conditions. As a result, the maximum permissible temperatures for the use of the device are limited, and its operational reliability at high temperatures is reduced. High-quality fuel combustion in the coolant supply cavities and / or unloading unit is hindered by flue gases coming into them from the furnace, which have a low oxygen content and inhibit combustion processes.

 The problem to which the invention is directed is to increase the operational reliability of a shaft heat exchanger, the permissible temperatures of heat treatment of materials in it, and reduce the cost of construction.

 The problem is solved due to the fact that the shaft heat exchanger of a rotary kiln for heat treatment of materials before being fed to a furnace containing a profiled shaft, solid or solid and louvered walls, arch floors, material loading and unloading units, coolant supply cavities located above the level of material slope , and the cavity for the removal of coolant, has at least one cavity for the removal of coolant, formed by a vault overlap and a solid wall and located above the level of natural ennogo repose of the material, thus removing the coolant cavity disposed in at least two tiers adjustment shaft.

 The described design of the heat exchanger removes temperature restrictions associated with the use of a gas exhaust system using louvered walls, provides the possibility of selecting gases having a higher temperature, which increases the permissible temperature of the heat treatment. Increased operational reliability and reduced cost of the heat exchanger.

 In addition, the heat exchanger housing is made in the form of two trapezoidal figures with a common base, which will simplify the design of the loading unit and increase the total working volume per unit area of the building occupied by the heat exchanger, in which the heat exchange of gases with the material is carried out, and therefore, to increase the efficiency of the heat exchanger in terms of the depth of heat recovery of exhaust gases.

 In the mine tiers, where the temperature of the sampled gases does not exceed the level required for the reliable operation of the metal structure, at least one sampling cavity is formed by vaulted overlap, louvred and continuous walls.

 The location of the coolant inlet and outlet cavities along the mine tiers in a checkerboard pattern will provide multidirectional movement of gases in the layer, which contributes to uniform heat treatment of the material.

 The supply of at least one coolant supply cavity with burner devices for autonomous heating makes it possible to increase the combustion temperature without gas contamination by the furnace gases, to minimize fuel underburning, and to improve the adjustable heat treatment process.

 The invention is illustrated by drawings, where figure 1 shows a General view of a shaft heat exchanger of a rotary kiln; figure 2 - its vertical section.

 The shaft heat exchanger includes a raw material loading unit 1, a profiled lined shaft 2 with solid walls 3, near which louvered walls 4 of heat-resistant shelves 5 are installed, and arch floors 6 installed in the central and lateral parts of the shaft 2, which form the required layer profile material 7, the supply system 8 and the removal of 9 gases, the unloading unit 10. The housing of the lined shaft 2 is made in the form of two trapezoidal figures with a common base.

 The raw material loading unit 1 is equipped with a loading funnel 11.

 The coolant (gas) supply system 8 includes the coolant supply ducts 12 and the coolant supply cavities — one central 13 formed by a vault 6, solid walls 3 of the shaft 2 and located above the level of natural slope of the material 7, and four side 14, 15, 16, 17 formed by vaulted ceilings 6 and walls 3 of the shaft 2, located above the level of natural slope of the material 7.

 The waste heat carrier (gas) removal system 9 includes coolant removal cavities - two central 18, 19 and four side 20, 21, 22 and 23, connected to the exhaust gas ducts 24.

 The cavity of the heat carrier 18-23 are located on the tiers of the heat exchanger in a checkerboard pattern.

 The Central cavity of the removal of the coolant 18, 19 is formed by vaulted ceilings 6 and solid walls 3 of the shaft 2.

 The lateral cavities of the coolant drain 20, 21 are formed by vaulted ceilings 6, the louvered walls 4, the solid walls of the shaft 2 and are located above the level of natural slope of the material 7. The lateral cavities of the heat carrier 22, 23 are formed by the vaulted ceilings 6, the solid walls 3 of the shaft 2 and are located above the level repose of material 7.

 The unloading unit of the material 10 is equipped with a pusher-unloader 25.

 The lower-level coolant supply cavities 14.15 are made with self-heating burners 26.

 Mine heat exchanger operates as follows.

 Raw material 7 is fed to the loading unit 1, from where it enters the working volume of the shaft heat exchanger, where it is heated with the accompanying technological processes (drying, calcination). At the exit of the hot material 7, the pusher-unloader 25 is fed into a rotary kiln.

 Gases entering the coolant supply cavity 13, 14, 15, 16, 17 are sucked away once, but in different directions, through the material layer 7.

 In the lower part of the heat exchanger, where the coolant supply cavities 14, 15 are located, the coolant is formed due to the combustion of natural gas by burners 26. Flue gases from the rotary kiln through the flues 12 enter the coolant supply cavities 13, 16, 17 and are sucked through the discharge unit 10.

 The exhaust gases are collected in the coolant removal cavities located in four tiers along the shaft height: on the fourth upper tier in the side cavities 22, 23, on the third tier in the central cavity 19, on the second tier in the side cavities 20, 21, on the first tier - in the central cavity 18. Then all the gases enter through the local flues into a common exhaust duct and are sent to the gas treatment.

 The described heat exchanger allows for the implementation of a four-tiered mine height selection of the coolant at elevated temperatures through the exhaust cavities of a simplified design, which increases the reliability of the device in question, reduces its cost and expands the technological capabilities of the unit, in particular, provides the possibility of smooth heating at the initial stage, required during heat treatment of wet briquetted or granular material.

Claims (5)

1. Shaft heat exchanger of a rotary kiln for heat treatment of material before feeding into the kiln, including a profiled shaft with solid or solid and louvered walls, vaulted floors, material loading and unloading units, coolant supply cavities located in staggered tiers of the heat exchanger above the level of material slope , and the cavity of the coolant, characterized in that at least one cavity of the coolant is formed by a vault overlap and solid walls and is located above the level of repose of the material, thus removing the coolant cavity disposed in at least two levels of height. 2. The shaft heat exchanger according to claim 1, characterized in that its body is made in the form of two trapezoidal figures with a common base. 3. A shaft heat exchanger according to any one of claims 1 and 2, characterized in that at least one outlet cavity is formed by a vault overlap, louvres and solid walls. 4. Shaft heat exchanger according to any one of claims 1 to 3, characterized in that the cavity of the heat transfer fluid are arranged in staggered tiers of the heat exchanger. 5. A shaft heat exchanger according to any one of claims 1 to 4, characterized in that at least one cavity for supplying the coolant is provided with burner devices for autonomous heating.

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