SU1645799A1 - Chain curtain of rotary furnace - Google Patents

Abstract

The invention relates to the design of a chain curtain of a rotary kiln and provides a reduction in fuel consumption and dust emission, improving product quality and kiln performance. The chain curtain of the rotary kiln 1 contains a section 2 of the flowable state of the charge, section 3 in the flexible state of the charge, guides screw 4, free-hanging single chains 5 and twin chains 6. In this case, in section 3 in the plastic mixture, the number of visits of the screw guide 4 the weight of chains 5, 6 is in the range of 0.9-1.3 times the ratio of the circumference of the furnace 1 and the length of chains 5 and 6, in section 2 of the fluid mixture at a length of 0.2-0.9 steps of the helical guide and weight of the chains 5 performed with double the number of visits, and ca circuits 5 in this area is the total weight of 0,05-0,26 chain curtain. 1 h. the item f-ly, 3 ill., 2 tab. Ј Os 4 SP VI th

Description

figure 1

The invention relates to a technique for heat treating materials in rotary kilns equipped with chain heat exchangers, and can be used in cement metallurgy, in the building materials industry.

The purpose of the invention is to reduce fuel consumption and pulverization, improving product quality and furnace performance.

FIG. 1 shows a sweep of a rotary kiln with a chain curtain; in fig. 2 - the same, cross section; Fig. 3 shows a section of a screw guide for fastening chains.

On the housing of the rotary kiln 1, in section 2 of the flowable state of the charge and on section 3, in the plastic state of the dried mixture, screw guide plates 4 are installed, on which free-hanging chains 5 fixed by one end are mounted. Batch the number of visits of the screw guides 4 of the sample is 0.9-1.3 ratio of the circumference of the inner surface of the furnace 1 and the length q of the chain 5; in the section 2 of the fluid mixture, the number of visits of the synth guides 4 of the sample 4 was performed. In section 3 of the plastic mixture, single and double chains 5 and 6 alternate along the length of the screw guides 4. Distance A between the suspension points of chains 5 and 6 along the length of the screw guides 4 equals 0.9-2 heights of the 5 chain link 5. Step Hb of the screw guides 4 of the hinge is 2-2.9 lengths of the chain 5. The length of 1C chains 5 is 0.3-0.9 of the diameter of the furnace D. The length w of section 2 of the liquid-fluid mixture with a double number of screw directions 4 is 0.20-0.9 steps Hb of the screw guide 4 of the hinge.

The mass of chains 5 in this area Och 0.05 - 0.26 of the total mass of the chain curtain 00ts.

The chain curtain works as follows.

The fluid flow charge is charged in bulk in a rotary kiln 1 with a chain curtain. As the drying progresses, the charge passes from the liquid (section 2) to the plastic (section 3) state, turns into large lumps, which then crack and crush on the subsequent sections of the chain veil, forming granules and partially grains. Some of the small fractions are taken up by the flow of heating gases and carried to the charging end.

A significant amount of dust sticks to the chains 5 moistened with a film of the charge in section 2 of a fluid mixture. The length of the section 2 flowable charge (0.20 - 0.9) Hv

ensures the overlap of the cross section of the furnace 1, excluding the possibility of dusty gases passing without the intersection of the chains 5 along the helical guide 4. Mass of chains 5 O (0.05 - 0.26) QOU ensures the density of the charge in section 2 of the fluid mixture at which Efficient heat exchange and trapping of dust from the surface of chains 5 moistened with a mixture film. The alternating single and remote circuits 5 and 6 on the section 3 in the flexible mixture provide for a sufficiently large specific pressure of the double chains 6 on the housing, which allows the housing to be cleaned of adhering charge, preventing build-up without excessively increasing the density of the suspension in this section 3, limiting transporting capacity of chains 5 and 6. The suspension points of the helix-adjacent chains 5 and 6 are located at a distance of 0.9-2 of the height of the link of chains 5 and 6, which ensures sufficient mobility of the chains 5 and 6 in the mount and its self-cleaning without turning the chains 5 and 6 around the fixing finger and forming the coil. Helical guide pitch

u l D,. about

But - here- (where p is the angle of the helical guide 4 to the longitudinal axis of the furnace 1; D is the diameter of the furnace 1, equal to 2 - 2.9 lengths of chains 5 and 6). provides a rational arrangement of chains 5 and b in a lower position on the body without forming shaft of chains 5 and 6 and balls, while maintaining a satisfactory transporting capacity for clods in a highly flexible mixture.

Running on the section 3 in the plastic mixture of the number of helix inlets of hanging up chains 5 and 6 within 0.9 - 1.3, the ratio of the circumference of the inner surface of the furnace 1 and the length of the chains 5 and b ensures an approximate equality of the length of the arc of a circle between adjacent screw guides 4 hangings of chains 5 and 6 and lengths of chains 5 and 6. Therefore chains 5 and 6, moving as the furnace 1 rotates into the lower position and placed on the surface of the housing, and then sliding along this surface, clean the housing well between the screw n directing 4 pendants from the stuck in the plastic mixture without leaving untreated dead zones (in the case of a too small number of visits of the suspension for a given length of chains 5 and 6, and not creating a shaft of chains 5 and 6 when laying them on the adjacent screw guide 4 ( in the case of too many visits for a given length of chains 5 and G). The length of chains 5 and 6 and,

Respectively, the ratio of the length of chains 5 and 6 to the diameter of the furnace 1 in section 3 in the explosive state of the mixture is chosen depending on the design of the furnace 1, its formation, the properties of the charge, the presence of a reserve for heat exchanger smoke exhausters, etc. to provide intensive heat exchange, a rational level of paleunos from the furnace 1, the formation of the particle size distribution of the dried mixture, uniform material advancement, moderate aerodynamic resistance of the chain zone. With the selected length of chains 5 and 6, the number of visits of the screw guide 4 in section 3 in the electroplastic mixture depends on the ratio of the circumference of the furnace 1 to the length of chains 5 and 6. When this ratio is less than 0.9, the number of visits of the screw guide 4 turns out to be excessively small accordingly, the length of the arc between adjacent screw guides 4 is excessively long. As a result, near the screw guides 4, the casing and the guides 4 are not effectively cleaned from growth, which leads to overgrowth of the drying zone, restriction of transport performance, overflow of the charge through the loading board, destabilization of movement and heat treatment of the material. When this ratio is more than 1.3, the number of visits of the screw guide 4 is excessively large, respectively, the length of the arc between the screw guide 4 neighbors is excessively small, chains 5 and 6, having a longer length, are laid on the adjacent guide 4 and chains 5 and 6 fixed on the adjacent guide 4. As a result, the lateral surfaces of the guides 4 are poorly cleaned, entanglement of chains 5 and 6 may occur, the shaft of chains 5 and 6 on the casing increases, which leads to clogging of the drying zone, entanglement of chains 5 and 6, bun reduce movement of the material, reduce the campaign of the furnace unit. The best results when the ratio is 0.95-1.05. In section 2 of the flowable charge at a length of 0.20-0.9 steps of the screw guide 4, the sample was made with twice the number of visits.

The increase in the number of visits in this area 2 is caused by the need to improve the overlap of the cross section of the furnace 1 with chains 5 to improve the trapping, intensifying heat exchange by covering the surfaces of the chains 5 with a fluid mixture film. The doubled number of visits compared with the subsequent in the course of material movement section 3 in the optic plastic mixture provides the most uniform material advancement in the transition section, since between each two screw guides 4 in this area 2 additional guides 4 are symmetrically placed, and there are no jolts material flow to the next section 3. This is facilitated by the convergence of the velocities of the fluid and in the plastic mixture at the junction of sections 2 -3, since 2 heel well flowable material creates more resistance to its displacement, less than multistart headstock

5 section 3 of a poorly displaced material in a plastic material. At section 2 of a fluid mixture with a doubled number of entries of a free-hanging helical curtain less than 0.20 pitch of a helical guide 0 of a hinge, the cross section of the furnace 1 is not covered by a carpet of chains 5 on a screw guide 4, the gas flow is not filtered through the carpet, but passes along the path of least resistance through

5, the uncovered part of the section is as if parallel to the carpet of chains 5. This worsens dust collection and heat transfer. When the length of this section 2 is greater than 0.9 steps of the screw guide 4 in the upper position of the points of suspension, there is provided an almost complete overlap of the cross section of the furnace 1 with chains 5 along the entire length of the screw guide 4. However, section 2 with an increased number of visits also takes

5 areas in the plastic mixture, which impedes the movement of the material, contributes to the overgrowth, destabilization of the movement and heat treatment of the material.

The mass of chains 5 in section 2 of the liquid of which the state of the charge with an increased number of visits of the helical guide 4 amounts to 0.05-0.26 of the total mass of the chain curtain. With a smaller share of chains 5 in this area 2, there is not enough effective dust collection on chains 5 moistened with film and heat transfer efficiency decreases. With a larger share of chains 5 in this area 2, part of the sample with an increased number of visits is found in section 3 that is poorly transported in This plastic material, which limits productivity, leads to charge overflow through the loading board, and destabilizes the process. In addition, aerodynamic drag may increase due to the need to maintain a high density of the sample in this area 2.

In section 3 of the plastic material, the sample is made of alternating along the length of single and double freestanding chains 5 and 6. This ensures, while maintaining a moderate density, to achieve a high pressure force of the double chains 6 on the case, which improves the condition of cleaning the case from adhering charge. In addition, with a rational small number of visits of the screw guide 4, this allows to achieve the required weight of the hinge without overly close proximity of the screw guide 4 chains 5 and 6 that are adjacent to the length of the screw guide, which could limit their mobility at the attachment points and facilitate overgrowth.

The distance between adjacent points of attachment along the helical guide 4 is 0.9-2 of the height of chain link 5 and 6. With a smaller relative distance of chain 5 and b in the attachment points, they have insufficient mobility, which causes overgrowth at the attachment points and jamming of the chains 5 and 6. At a greater distance, it is possible for the chain link 5 and 6 to scroll around the securing pin, which can lead to tangles. The most rational distance is 1.2-1.5 link heights.

The pitch of the screw guides 4 of the hinge is 2-2.9 times the length of chains 5 and 6. The length of chain 5 and 5 is chosen from the condition of heat exchange, pulverization, aerodynamic resistance to achieve the required density of overhang, overlap of the cross section of the furnace 1, the specific pressure of chains 5 and 6 on the build-up that forms on the housing. The longer the chains 5 and b, the greater the longitudinal pitch of the screw guides 4, hinges, i.e., the smaller the angle of rotation of the screw guides 4 to the longitudinal axis in order to avoid the mass concentration of the chains 5 and 6 on the short section of the furnace 1, causing the formation of a shaft chains 5 and b of tangles that violate the movement of the material, leading to its regrinding. When the pitch of the screw guides 4 weights less than 2 chain lengths 5 and b, because of the large angle of rotation of the screw guides 4, coils of chains 5 and 6 are formed, which impairs heat transfer, disrupts the material transport in a plastic state, increases the dustiness, destabilizes the mode. When the pitch of the screw guides 4 is more than 2.9 of the lengths of chains 5 and 6, due to a decrease in the angle of rotation of the screw guides 4, the transportation of lumps in the plastic mixture worsens, the specific pressure of chains 5 and 6 on the body decreases and, accordingly, it is cleaned of naps. To maintain a rational relationship between the pitch of the screw guides 4 hinges and the length of chains 5 and 6, if necessary, to significantly increase the length

chains 5 and b to achieve the required mass of the chain heat exchanger without excessively reducing the angle of rotation of the screw guides 4 at which the

transportation of lumps, it is possible to increase the diameter of the furnace body 1 in the drying zone.

PRI me R. The proposed chain curtain of the rotary kiln for sintering the alumina containing charge, which is prone to build-up in the drying phase, is made on a rotary kiln 1 with a size of 5x185 m, having a slope of 3% and a rotation frequency of 2 rpm.

5The test results of the furnace unit

with different characteristics of the chain veil are given in table. 1. In experiment 1, a 3-way free-hanging chain-curtain was adopted along the entire length of the sections of flowable and

0 plastic charge, which is the basic object. In experiments 2-7, the proposed chain-curtain was tested, and in experiments 3-6, the structural characteristics of the curtain were within the limits specified. Wherein

5 in experiment 6, the diameter of the drying zone of the furnace 1 in section 3 in the electroplastic state of the charge was increased to 5.6 m.

The data table. Figure 1 shows the advantages of the proposed device and the optimality of the claimed range of changes in design characteristics.

The proposed dual chains 6 provide a sufficiently high specific pressure on the body and its effective cleaning.

5 on a larger surface than a small size known fastener elements. A hinge tightness and the avoidance of the formation of a shaft of chains 5 and b, which impede the transportation of material,

0 is achieved by correspondingly alternating along the length of the screw guides 4 of the dual and single chains 5 and 6.

Thus, the proposed dual chains 6 alternating with single

5 chains 5, as compared with chains equipped with auxiliary elements, provide a reduction in the specific consumption of chains by 20% over the course of a campaign, a -1% increase in productivity, a decrease in

0 fuel consumption by 1.3%.

The operational indicators of the compared options during the 6-month operation are given in Table. 2

The introduction of the proposed device

5 provides an increase in the productivity of the furnace by 2-3.5%. reduction in fuel consumption by 1.5–3%, dust removal by 20–30%, an increase in extraction of alumina from oil by 0.7–1.5 abs.%, an increase in the proportion of guardianship with a required degree of heat treatment, characterized by an increase in the proportion of required moisture capacity of 15-25%.

Claims (2)

1. A chain curtain of a rotary kiln, mainly for sintering the alumina-containing charge, containing free-hanging chains, the suspension points of which are located along a multiple-thread helical guide, made with twice the number of entries in the liquid state of the charge compared to the section in a flexible state in which the hitch is made with reinforcing elements, characterized in that, in order to reduce fuel consumption and dust removal, to improve product quality and the productivity of the furnace 1, the length of the section of the fluid state of the charge is 0.2-0.9 degrees of the pitch of the helical guide; the weight of the chains in this section is 0.05-0.26 the total mass of the chain curtain, and the number of visits of the screw guide linkage of the chains at the site in the ecoplastic mixture is 0.9-1.3 times the ratio of the circumference of the inner surface of the furnace and chain length. 2. The curtain of claim 1, characterized in that the amplifying elements at the site in the zoplastic state of the charge are made in the form of double chains alternating along the length of the screw guide with single chains, and the pitch of the screw guide hinges is 2 -2.9 chain lengths. Test the proposed device Table 1 Continued tabl, 1 table 2 FIG. 2 3