SU1670316A1 - Chain curtain of rotary furnace - Google Patents

Abstract

The invention provides for the intensification of heat exchange, reduction of dust removal, buildup, and lining wear. The curtain chain contains free-hanging chains fixed at one end on the body, the suspension points of which are located along multiple helical lines. The hinge helix lines are made of 2-4 parallel rows of 4 chains, the average distance between which is 0.02-0.08 furnace diameter; chains are fastened along screw lines on longitudinal rows of plates 5 with a length of 0.05-0.2 in diameter of the furnace rigidly connected to the casing; plates 5 are displaced in adjacent rows along the circumference of the furnace diameter 0.003-0.015. 1 hp ff, 1 tabl, 2 ill.

Description

This invention relates to a technique for firing materials in rotary kilns, for example, in the cement industry.

The aim of the invention is to intensify heat exchange, reduce dust removal, buildup and lining wear.

Fig. 1 shows a scan of the chain curtain of a rotary kiln; Fig. 2 illustrates the attachment of chains on longitudinal rows of plates.

On the casing 1 of the rotary kiln, one end of a free-hanging chain 2 is fixed, the suspension points of which are located along a multiple helix 3, each of which is composed of two to four parallel rows 4, the distance between which along the arc of a circle is 0.02-0 , 08 of the furnace diameter D. In this case, the width of each run of the helix of the sample will be from (2-1) -0.020 0.02D to (4-1) -0.08D 0.240.

Chains 2 are fixed on longitudinal rows of metal plates 5 rigidly connected to housing 1. The length b of plates 5 is 0.05-0.2 D. Plates 5 in adjacent longitudinal rows along the length of the furnace are offset from the circumference by a distance of 0.003 -0,0150.

The inclination of the screw lines 3 weighed to the longitudinal axis of the furnace, mainly, 60 ° (30-65 °).

The number of screw connections can be constant or vary along the length of the furnace, depending on the changing properties of the dried and heated mixture. The most appropriate number of visits screw attachment 3-8.

The density of the sample can also vary widely: 2.5-14 m2 / m2. Adjusting the density of the sample is provided by changing the distance between adjacent chains 2 along the length of the guide helixes 3. by changing the number

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parallel rows 4 in one guide helix 3, by changing the number of chains 2 attached to one suspension point — one or two chains 2, with their alternation along the length of the screw guide.

For ease of attachment and the possibility of changing the attachment point when the hole is worn, the aperture of the plate 5 is provided with several apertures in which fastening fingers are inserted. chain link 2.

The chain curtain of the rotary kiln operates as follows.

The liquid flow raw material mixture is injected in bulk into a rotary kiln and, due to the inclination and rotation of the kiln, is moved to the discharge end, dried and heated and heated due to the heat moving towards the combustion products. As it dries, the physical state of the charge significantly changes from liquid at the loading end to the plastic in the middle part and granulated at the discharge end of the chain curtain.

The location of chains 2 along a multiple helix 3 in the direction of rotation of the furnace (the cold loading end of the helix 3 emerges first from the material layer increases the speed of transport of the charge, especially in the area of the plastic mixture, where a build-up on housing 1 and chains 2, large clod.

A limited number of visits of the screw line 3 of the hinge provides large channels for the passage of gases with reduced aerodynamic drag, laying chains 2 in the lower position on body 1 in the form of a uniform carpet without sills and tangles, which reduces abrasion of the granules by chains 2 and intensifies heat transfer to the material.

The implementation of each helix guide 3 hinge from two to four parallel rows 4 ensures the movement of the flow of heating gases not only along the helical wall of the channels formed by the descending chains 2, but also the filtration of a significant amount of gases through the helical wall of the hanging chains 2, as in this case, it has a sufficiently small aerodynamic resistance due to the large distance between the adjacent chains 2 along the screw while maintaining the total surface and density of the sample

chains 2 at the required high enough level.

When filtering gases in the transverse direction between adjacent screw channels formed by the hanging chains 2, the entire surface of the chains 2 (and not just its part facing the inside of the screw channels) is involved in the heat exchange with the gas flow, which intensifies the heat exchange. A decrease in the aerodynamic resistance of the hanging chains 2 in parallel screw rows 4 provides a more uniform velocity field in height with a decrease in the amount of gases passing 5 into the free space under the chains 2, which reduces the separation of particles from the layer, i.e. dust removal, improves dust collection on the surface of chains 2 at the charging end. The sufficiently high mobility of the fastener links of chains 2 with a sufficiently high weight of the sample due to two or four parallel rows of the water helical line 3 of the linkage prevents the formation of build-up along the line of fastening points and excludes the basis for the subsequent overgrowing of housing 1, jamming of chains 2, forming a wave-like movement of the material due to the unevenness of the resulting growth. When the distance between parallel rows of chains 2 in one helix 3 is less than 0.020, a build-up of drying mixture is formed, which is fixed at too close points of attachment. When the value of this distance is no more than 0.080, a large area along the arc of the circumference of the furnace body 1 between parallel rows 4 is not cleaned by sliding chains 2 and also a build-up between the rows is formed.

0 The width of each run of the helix 3 of several rows of 4 chains 2 is 0.02-0.240. With a smaller approach width, the weight of the sample increases excessively in the approach, which increases the number of

5 of gas passing under chains 2 with an increase in dust extraction, and reduces the amount of gases that are filtered through chains 2 with deterioration of washing of chains 2 and heat exchange. Poor cleaning by sliding chains 2 of the furnace surface across the approach width leads to the formation of a high build-up, the formation of a wave-like mode of movement of the material destabilizing the mode. With a greater width of entry is formed

5 an excessively wide build-up in chains x 2 (although smaller than in the previous case), the neighboring approaches of the helix 3 of the fastening of the chains 2 come too close together around the circumference, which leads to the ends of the chains 2 of one approach to the attachment points of another

call. This increases the resistance to the advancement of the material, contributes to the entanglement of the chains 2 and the deterioration of the cleaning of the housing 1 between passes.

Making plates 5 of a limited length equal to 0.05 0.20, in combination with their circumferential displacement by 0.003-0.0150, provides a more complete overlap of the cross section for the passage of gas through the screw wall of the hanging chains 2, improves their cleansing and heat transfer. from gases. In addition, it provides a more uniform movement of the material and shoveling it while passing through the fastening strip of the chains 2.

When the length of the fastening metal plates 5 is less than 0.05D, the mounting is complicated, the possibility of making several holes for attaching chains 2 is not provided, which eliminates the possibility of the weights of chains 2 to the adjacent hole when the hole is worn with an increase in the service life of the plate 5 curtains with deterioration of heat transfer and deterioration of dust collection in the loading area. When the length of the plates 5 is more than 0.2V, the possibility of sufficiently effective overlapping by chains 2 due to their displacement of the cross section for the passage of gases decreases, which impairs heat transfer and dust collection. In addition, excessive length of the plates 5 leads to the development of thermal deformations with the separation of the plates and the destruction of the concrete lining of the furnace

When the plates 5 are displaced around the circumference in adjacent islands less than 0.0030, it is not possible to reach the section over a relatively short section, which worsens washing of the chains with 2 gases and reduces the heat transfer intensity, increases dust removal. When offset more than 0.0105 also a sufficiently complete overlap of the cross sections with chains 2 is not achieved, as a result of which the efficiency of heat transfer is reduced. Rational displacement of G.TTYRTSY when its value is 0.008-0.010

The table shows examples that characterize the proposed chain veil in comparison with the known

In experiment 1 (base object), a multiple-screw connection of free-running chains was made; weighed on screw guide chains in one row of 8 test 2, the sample was made according to the prototype.

In experiments 3-7, the chain-curtain was made in accordance with the drawing, and in experiments 4-6, the design characteristics are within the proposed limits.

The chain curtain is made in a rotary kiln with a size of 5 x 185 m. Used for burning cement raw material mixture, prepared on the basis of belite sludge - waste of alumina production. The characteristic properties of this mixture are low humidity (32% versus 35-40% in traditional mixtures), which determines the reduced dusting ability of the loading section of the chain curtain and lowered heat of clinker formation (250 kcal / kg of clinker against 440 kcal / kg of clinker in traditional cement mixtures ) conditional

5 increased furnace productivity and the amount of material that was simultaneously in the chain curtain.

The data in the table confirm that “the use of the proposed chain curtain provides an increase in productivity, a reduction in specific fuel consumption, a decrease in dust and dust, an increase in the aerodynamic resistance of the furnace, an increase in activity

5 cement by stabilizing the process and improving heat treatment, reducing dust circulation

The advantages of the proposed veil in comparison with the prototype are as follows.

Fastening of free-running chains 2 arranged along a helix on separate longitudinal metal plates 5 reduces abrasive wear.

5 linings, since they limit the slip path of chain 2, if they are made a height greater than the height of the lining. If the height of the plates 5 is equal to the height of the lining (and the attachment points of the chains 2 are located in the linings of the linings), as the surface layer of the lining wears, a depression forms between the plates 5, in which the material granules are retained and subsequently the chains 2 slide along these granules,

5 as on the rollers, which eliminates the subsequent abrasion of the lining

When mounted on longitudinal plates 5, the surface of the carpet of hanging chains 2 is not strictly screw, as in prototype, but broken, which increases the practical surface of washing out of chains 2 with heating gases, facilitates the penetration of gas into the volume of helix 3 of several rows of 4 chains 2 i.e. intensification of heat transfer, dust collection, reduces aerodynamic drag.

The 3 attachment points located along the broken helix are easier to remove from adhering material by sliding chains 2

Making longitudinal plates 5 of limited length 0.05-0.20 in combination with their circumferential displacement of 0.003-0.015D provides a more complete overlap of the cross section for the passage of gas through the helical carpet of hanging chains 2, improves their flushing and heat transfer, in addition, Provides for more intensive material overturning when passing through the fastening strip of chains 2.

Each run is made of several rows of chains, which is so that, in order to intensify heat exchange, reduce dust loss, build up and wear of the lining, the chains are fixed on 0.05-0 long plates connected to the body, 2 furnace diameters offset in adjacent rows along the circumference of a distance

0 0.003-0.015 of its diameter.

Claims (2)

Invention Formula 2. The curtain chain according to claim 1, distinguished1. The chain curtain of the rotary kiln, due to the fact that the width of each approach containing loosely attached chains of several p on the casing attached to one end of a screw line, hanging chains are located between 0.02 and 0.24 diameters mounted on multiple screw furnaces. Material Editor T. Klyukina  FIG. 2 Compiled by L. Petrova Tehred M. Morgental / Fp.1 Proofreader T. Malets