RU92720U1 - CHAIN FOR CHAIN PURPOSE OF ROTARY FURNACE - Google Patents

Abstract

A chain for a chain curtain of a rotary kiln, containing round or oval links with an internal curved surface in cross section and a stiffener on the outer end surface of the link along its perimeter, characterized in that the stiffener is made of a flat radial ring symmetrically to the axis of the link, while the intersection of the planes of the rib and the links are made at right angles without external angular radii, the internal radii of the transition to the end surface of the link are 3-6 mm, and the thickness of the rib and the total height of the body of the link with the rib avny 0.2-0.5 and 1-2 respectively link width in a projection onto its cross-sectional plane.

Description

The utility model relates to heat exchangers for equipment for the production of cement, lime and other binders, namely, to chain curtains of rotary kilns.

Chain curtains have gained predominance as the most effective intra-furnace heat exchangers in the wet method of cement production. They are hung in the furnace according to design schemes for the development of the heat transfer surface between hot gases and raw materials and to help move the raw materials through the furnace, to intensify the processes of heating, drying and decarbonization of sludge during the firing of cement clinker and other products. Chain curtains perform not only the heat transfer function, but also affect the formation and collection of dust, mixing and movement of material and gases, the stability of the lining of the furnace and the formation of accretions in the chain zone. As the main heat engineering element of chain curtains, heat exchange chains to a large extent determine the operational and economic efficiency of the latter, which depends mainly on the size of the outer surface of a unit of length and mass of the chain, based on which the diameter and shape of the chain link are selected. This takes into account both the adhesive-cohesive properties of the used sludge, that is, its possible sticking to chains and critical viscosity, as well as the ability to break pieces and improve the formation of granules, to destruction and abrasion of the calcined material, as well as the type of heat transfer in a specific area of the chain curtain - convective or regenerative.

In the building materials industry, welded and cast chains consisting of oval or round links having a round or D-shaped cross section are used in the heat exchange chain curtains. Also known are chains of oval and round links with section sections in the form of ovals, ellipses, eights, triangles, polygons (GOST 13237-67; SU 330321, 12/27/1966; SU 450947, 03/12/1973; E.I. Khodorov, Cement kiln industry, Stroyizdat, Leningrad, 1968, p. 59-61; O.A. Nesvizhsky, Durability of wearing parts of cement equipment, Engineering, Moscow, 1968, p. 179-193; V.I.Satarin and others. Cement industry for abroad, Gosstroyizdat, M., p. 113; US 3427801, 02/18/1969; GB 1100831, 01/24/1968; EAPO 010711, 03/31/2008).

Known chains of welded links of a round or oval shape with a round or oval section of the links do not fulfill their technological purpose in furnaces efficiently enough, they are quickly destroyed in the environment of the sludge due to abrasive wear of the links and in the places of welding and oxidation of the chain material. Such chains are also not rational for self-cleaning from sludge and preventing the formation of sludge rings. Cast chains are more durable in case of articulated abrasion and abrasive action of the fired material, but they slightly exceed the welded ones in terms of heat and mass transfer in the process of changes in the rheology of raw materials in the furnace zones of drying, heating and decarbonization. The thermodynamics of heat transfer by the mass of links from their surface, as well as the dependence of the calculated efficiency of the chains for the formation of granules on their specific surface, determine the minimum values of the heat exchange surfaces of the chains in the case of sections of the links in the form of a circle or oval, which forces to increase the calculated density of the chain curtain. All of these chain designs do not allow sufficient intensification of heat and mass transfer processes, which prevents the expansion of the chain curtains to the hot end of the furnace.

In its technical essence, the prototype analogue closest to the utility model is a chain for a chain heat exchange curtain of a rotary kiln, containing round or oval links with an internal curved surface in cross section and a wavy stiffener on the outer end surface of the link along its perimeter (EAPO 010711, 03/31/2008).

Although this chain, as shown by the practice of operating in the heating and decarbonization zones of large-diameter furnaces, is more durable, it also has the main drawback of the known chains: the inability to increase the heat transfer coefficient without a significant increase in the size and mass of the links. At the same time, the design of the link in the part of the corrugated rib does not have sufficient adaptability for the industrial production of such chains.

The objective of the utility model is to develop a new, more technologically advanced circuit design with improved thermal performance with the optimal ratio “heat transfer surface - mass of the chain link” for each of the chain links.

This problem is solved in that in a chain for a chain heat exchange curtain of a rotary furnace containing round and oval links with an internal curved surface in cross section and a stiffener on the outer end surface of the link along its perimeter, the stiffener is made with a flat radial ring symmetrically to the axis of the link, This intersection of the planes of the rib and the link is made at right angles without external angular radii, the internal radii of the transition to the end surface of the link are 3-6 mm, and the thickness of the rib and the total height the body of a link with an edge is equal to 0.2-0.5 and 1-2 of the width of the link in the projection of its cross section onto the plane.

The essence of the utility model is illustrated by drawings, in which:

figure 1 schematically shows a fragment of a chain in the embodiment with round links;

figure 2 is a fragment of a chain in the embodiment with oval links;

figure 3 - a single round link (plan view);

figure 4 - a single oval link (plan view);

figure 5 is a section aa in figure 3 and 4;

Fig.6 is a section bB in Fig.1 and 2;

Fig.7 is a view In section aa in Fig.5.

The chain consists of links of a round 1 or oval 2 shape, the inner surfaces 3 of which are made curved. On the external end surfaces 4 along the perimeter of the links, a stiffener 5 is made with a flat radial ring symmetrical to the axis of the links, the intersections of the planes of which are made at right angles without external angular radii, the internal radii of the transition to the end surface of the link are 3-6 mm, and the thickness of the rib and the overall height the body of a link with an edge is equal to 0.2-0.5 and 1-2 of the width of the link in the projection of its cross section onto the plane.

The ratios of the sizes of the elements of round or oval links (D, L, B, H, R, h, t) are given in Tables 1 and 2, respectively. In the indicated intervals of the relations, the sizes of the links for the chains of the corresponding technological zones of the furnaces are selected.

Table 1 Round links D AT N R h t 2 ... 5 V one 1 ... 2 V 0.5 D 0.4 ... 0.6 V 0.2 ... 0.5 V table 2 Oval links L AT N R h t 2 ... 5 V one 1 ... 2 V 0.5 D 0.4 ... 0.6 V 0.2 ... 0.5 V

A chain with sections of links made in accordance with this utility model has practically the same contact resistance with the known chains at the joints of the links, provided that the masses and sizes of the joint of their individual links are equal. However, the geometric shape and design of the section of the link, the presence of a radially located flat annular stiffener along the outer surface of the links, crossed at right angles to the plane of which significantly (not less than 30%) increase the heat exchange surface of the chain, significantly intensify regenerative heat transfer in the gas system flow - chain curtain - material ", optimizing the entire firing process and reducing heat consumption in the furnace. Due to the design of the link, there are multidirectional forces of breaking and separating the sludge film adhering to the chain in the zones of its drying and heating, which contributes to the quick self-cleaning of the chains in front of the decarbonization zone, reducing the possibility of ring formation in the furnace and excessive deformation of the material granules.

A more developed heat transfer surface of the proposed chains when manufacturing them from alloys with high heat resistance allows you to advance the chain curtain into the heat-stressed sections of the hot end of the furnace with gas flow temperatures up to 1200 ° C, use these chains as universal in all technological zones of a rotary kiln in the production of cement, lime and other binders.

Claims (1)

A chain for a chain curtain of a rotary kiln containing round or oval links with an internal curved surface in cross section and a stiffener on the outer end surface of the link along its perimeter, characterized in that the stiffener is made of a flat radial ring symmetrically to the axis of the link, while the intersection of the planes of the rib and the links are made at right angles without external angular radii, the internal radii of the transition to the end surface of the link are 3-6 mm, and the thickness of the rib and the total height of the body of the link with the rib avny 0.2-0.5 and 1-2 respectively link width in a projection onto its cross-sectional plane.