EA010710B1 - Chain for chained curtain of calcining rotary kiln - Google Patents

Abstract

The invention relates to equipment for producing construction materials, namely to inner-furnace heat-exchange devices of calcining rotary kilns for producing cement, lime and other binders from high-moisture feedstock, namely to chained curtains with heat-exchange chains comprising round or oval links with outer side flat surfaces which are embodied wavy along links perimeter with radially directed wave crests, the crowns of wave crest on one link side surface correspond to wave troughs on its opposite side, the ratio of the link width measured in crowns of wave crest in its transversal section to the link width in its longitudinal section is 0.5…2.

Description

The invention relates to heat engineering equipment for the production of building materials, in particular to intrahepatic heat exchangers of kiln rotary kilns for the production of cement, lime and other binders from high-moisture raw materials.

The most common intrahepatic heat exchangers are chain curtains of various designs. The purpose of the chain curtains is to reduce the duration of the preparatory firing stages by intensifying heat exchange in the preparatory zones of the furnace, and also contribute to the partial sedimentation of dust from the dust and gas flow in the wet material section at the cold end of the furnace.

The economic efficiency of chain curtains directly depends on the operability of the chain, the main indicators of which are the size of the outer surface of a unit of its length and mass, based on which the diameter of the chain link and its shape are selected, and the adhesion-adhesion properties of the sludge are evaluated, i.e. sticking it to the chains and its critical viscosity, as well as the ability to destroy and abrasion of the granules.

For chain curtains in the domestic cement industry, mainly welded (less commonly cast) chains are used, consisting of round or oval links (GOST 13237-67), having a cross section in the form of various ovals (8I 330321, 27.12.1966, 8I 450947, 12.03.1973 ). In the foreign industry, both welded and cast chains with round or oval links are used in chain curtains, in which the cross section can be made, for example, elliptical, or in the form of a figure eight, or T-shaped (V.I. Satarin and others. Cement industry abroad, Gosstroyizdat, Moscow, 1963, p. 113, I8 3427801, 18.02.1969, CB 1100831, 01.24.1968).

Known chains of welded links of round or oval shape with their relatively low price do not efficiently perform their technological purpose in furnaces - their round (or oval) section limits the heat exchange surface, forcing to increase the calculated curtain density. At the same time, such chains are not rational from the point of view of self-cleaning of sludge and preventing the formation of sludge rings, and cast chains with an elliptical link form, although more durable with hinged abrasion of links, are slightly higher than the welded chains in terms of heat and mass transfer in all zones of rotary kilns, before total in the areas of drying, heating and decarbonization of raw materials. In addition, all these chain designs do not allow to intensify the heat and mass transfer processes associated with the further expansion of the chain curtain to the hot end of the furnace.

According to its technical essence, the analogue closest to the invention is that the prototype is a chain for a chain curtain of a rotary kiln containing round or oval links with external flat side surfaces (8I 687328, 03/31/1978).

This chain, as shown by the practice of their operation, especially in the areas of heating and decarbonization of large-diameter furnaces, has all the main disadvantages of the known chains: limited durability and the inability to increase the heat transfer coefficient without a significant increase in the size and weight of the links.

The objective of the invention is to develop new designs of chains with improved thermal performance with an optimal ratio of "heat exchange surface - unit weight" for each of the chain links.

This task is solved by the fact that in a chain for a chain curtain of a rotary kiln containing round or oval links with lateral flat surfaces, the latter along the perimeter of the links are wavy with radially directed wave crests, and the tops of the wave crests on one side surface of the link correspond to the wave troughs on its opposite side surface, while the ratio of the thickness of the link in the dimension along the tops of the crests of the waves in its cross section to the width of the link in its longitudinal section is 1: 0.5-2.

In the known technical solutions are not found these distinctive features in their entirety.

The invention is illustrated by drawings, in which:

in fig. 1 schematically depicts a fragment of a chain in the variant with round links;

in fig. 2 - a single circular link (plan view);

in fig. 3 is a section A-A in FIG. one;

in fig. 4 is a section BB in FIG. one;

in fig. 5 is a section B in FIG. 3;

in fig. 6 — chain fragment in the variant with oval links;

in fig. 7 - single oval link (plan view);

in fig. 8 - section GG in FIG. 7;

in fig. 9 is a section DD in FIG. 6;

in fig. 10 is a view E of a section of the HG in FIG. eight.

The chain consists of links of round 1 or oval 2 forms. The side surfaces 3 of each link are made wavy with radially directed ridges 4. In this case, the wave crests on one side surface of the link correspond to the cavities 5 on the opposite side surface, and the ratio of the thickness of the link B in measurement along the tops of the crests in its transverse cross section (Fig. 3, seche

- 1010710 A-A and FIG. 8, the section H-D) to the width of the link H in its longitudinal section (Fig. 4, section BB and Fig. 9, section DDD) is 1: 0.5-2. In the specified interval of relations, the sizes of the links for the chains of the corresponding technological zone of the furnace are selected. The ratios of the sizes of elements of round or oval links (I, B, H, K, L ₁ , L ₂ , g) are given respectively in Table. 1 and 2.

Table 1

Round links

£> AT n I B! l ₂ R 2 ... 55 one 0.5 ... 25 0.25 ... 1 V 0.25 ... 0.75 5 0.25 ... 0.75 5 0.1 ... 0.35

table 2

Oval links

s five n AT B) R G / 2 ..55 one 0.5 ... 2 5 0.25 ... 1 V 0.25 ... 0.75 V 0.25 ... 0.75 5 0.1 ... 0.3 in 0.1 ... 0.3 5

Although chains with known forms of links and chains with forms of links made in accordance with the invention, having equal dimensions, have almost the same contact wear resistance at the junction points of the links in the chain, however, the undulating configuration of the links allows to significantly increase their heat exchange surface (not less than 30%), which, by optimizing the burning of clinker, reduces heat loss and intensifies heat transfer from the gas flow to the material.

At the same time, the sludge film sticking to the chains is easier to separate from the surface of the links, because in the relief of the film (repeating the relief of the links), there are multidirectional forces of its breaking and separation from the links, which contributes to fast self-cleaning of the chains before the decarbonization zone and prevent excessive deformation of the material granules.

Thus, a more developed heat exchange surface of the proposed chains, using appropriate heat-resistant steels, allows moving the chain curtain to the heat-stressed parts of the hot end of the furnace with temperatures up to 1100-1200 ° С, which makes these chains universal for hanging in all technological zones of kilns.

Claims (1)

CLAIM A chain for a chain curtain of a kiln containing round or oval links with external lateral flat surfaces, characterized in that the lateral surfaces along the perimeter of the links are wave-like with radially directed wave crests, and the tops of the wave crests on one side surface of the link correspond to the troughs of the waves on the opposite side thereof lateral surface, the ratio of the thickness of the link in the measurement along the tops of the wave crests in its cross section to the width of the link in its longitudinal section is 0.5-2.