1. A construction method of a kiln top structure of a gas-fired lime shaft kiln is characterized by comprising the following steps:

obtaining a plurality of fan-shaped first precast blocks, wherein the thickness of each first precast block is 230mm for 170-;

obtaining at least two groups of prefabricated blocks, wherein each group of prefabricated blocks comprises two fan-shaped second prefabricated blocks, the thickness, the top arc length and the bottom arc length of each second prefabricated block are the same as those of the first prefabricated block, the weight of each second prefabricated block is smaller than that of the first prefabricated block and not smaller than 550kg, and a semicircular hole with the radius of 280 plus 320mm and used for forming a smoke outlet is formed in one adjacent side edge of each second prefabricated block;

respectively hoisting the plurality of first prefabricated blocks and the prefabricated blocks to the circumferential direction of a central chimney and lower than a feeding port of the central chimney, splicing the plurality of first prefabricated blocks and the prefabricated blocks at the top end of a kiln body of the gas-fired lime shaft kiln to form a frustum structure surrounding the circumferential direction of the central chimney, butting two semicircular holes of each group of prefabricated blocks to form a circular smoke outlet, and then binding and hooping by using steel belts;

and plugging one end of the central chimney extending out of the frustum structure and higher than the feed inlet.

2. The construction method according to claim 1,

the step of splicing the plurality of first precast blocks and the precast blocks to form a frustum structure surrounding the circumference of the central chimney comprises the following steps: the smoke outlet is made symmetrical along the axis of the central chimney.

3. The construction method according to claim 2, wherein the number of the first precast blocks is four, the number of the precast blocks is two, and the step of hoisting the plurality of first precast blocks and the precast blocks to the circumferential direction of the central chimney respectively comprises: and sequentially hoisting and enclosing the first precast blocks, the precast block, the two first precast blocks and the precast block in the circumferential direction of the central chimney.

4. The construction method according to claim 2, further comprising: after the steel band is tightly bound and hooped, a heat-resistant steel pipe is arranged in the smoke exhaust port.

5. The construction method as claimed in claim 1, wherein the first precast block and the second precast block are each made by:

mixing the raw materials, pouring, vibrating, molding, curing at room temperature, and baking at 150 ℃ for 20-28h to obtain the product;

wherein the raw materials comprise: mixing a material, a water reducing agent and water, wherein the addition amount of the water reducing agent is 0.10-0.25 wt% of the mixture, and the addition amount of the water is 5.0-6.5 wt% of the mixture;

the mixed material comprises 75-90 wt% of high-alumina bauxite clinker, 3-15 wt% of kyanite fine powder, 1-10 wt% of alumina micro powder, 0-10 wt% of aluminate cement and 1-5 wt% of silicon-aluminum gel.

6. The construction method according to claim 1, further comprising embedding a hoisting piece in each of the first precast block and the second precast block, wherein the hoisting pieces are symmetrically arranged along a center connecting line of a top arc length and a bottom arc length, and the hoisting pieces are located at 2/3 of the length of the center connecting line and are offset from one end close to the top arc length.

7. The kiln top structure of the gas-fired lime shaft kiln is characterized by comprising a central chimney and a frustum structure, wherein the central chimney is provided with a feed inlet and a material door for sealing the feed inlet, the feed inlet is positioned outside the frustum structure, the end part of one end, extending out of the frustum structure, of the central chimney is sealed, the frustum structure is arranged at the top end of a kiln body of the gas-fired lime shaft kiln and surrounds the central chimney, and the frustum structure is provided with at least two smoke outlets for outputting smoke;

the frustum structure is obtained by splicing a plurality of fan-shaped first precast blocks and at least two groups of precast blocks, the thickness of the first precast blocks is 230mm, the top arc length is 600mm and 650mm, the bottom arc length is 1300 mm and 1400mm, and the weight is more than 550kg and not more than 650 kg;

the prefabricated blocks comprise two fan-shaped second prefabricated blocks, the thickness, the top arc length and the bottom arc length of the second prefabricated blocks are the same as those of the first prefabricated blocks, the weight of the second prefabricated blocks is smaller than that of the first prefabricated blocks and not smaller than 550kg, semicircular holes with the radius of 280-320mm for forming the smoke exhaust port are formed in the adjacent side edges of the two second prefabricated blocks, and the two semicircular holes of each group of prefabricated blocks are in butt joint to form the circular smoke exhaust port.

8. The kiln top structure of a gas-fired lime shaft kiln as recited in claim 7, wherein the at least two smoke outlets are arranged indirectly and equidistantly along the circumference of the frustum structure.

9. The kiln top structure of the gas-fired lime shaft kiln as recited in claim 7, wherein the number of the smoke discharge ports is two, and the two smoke discharge ports are symmetrically arranged along the axis of the central chimney.

10. The kiln top structure of the gas-fired lime shaft kiln according to claim 7, wherein the first precast block and the second precast block are provided with hanging pieces, wherein the hanging pieces are symmetrically arranged along a central connecting line of the top arc length and the bottom arc length, and the hanging pieces are positioned at 2/3 of the length of the central connecting line and are offset from one end close to the top arc length.

Background

The gas-burnt lime shaft kiln belongs to a kiln in metallurgical industry, is one of the present lime calcination thermal equipment, belongs to a straight cylinder type kiln, adopts 10 peripheral sleeve type burners which are respectively arranged in an upper row and a lower row, takes blast furnace gas, converter gas and other gases as fuels to produce active lime, has the advantages of low-heat value gas availability, over 8 years of kiln life, small investment and short construction period, and is one of the main kiln types for lime production in ferrous metallurgy industry. The gas-fired lime shaft kiln uses coal gas as fuel and is matched with a combustion-supporting air process, a large amount of hot flue gas is generated in the production process, the temperature of the hot flue gas of the kiln top structure of the gas-fired lime shaft kiln reaches more than 650 ℃, and the hot flue gas contains a large amount of coarse-particle dust, the kiln top structure of the gas-fired lime shaft kiln is subjected to mechanical scouring of high-temperature dust-containing flue gas for a long time and mechanical vibration in the charging process, and the thermal expansion hot flue gas of the kiln top structure of the gas-fired lime shaft kiln easily escapes, so that the kiln top structure of the gas-fired lime shaft kiln emits dust and burns and damages mechanical and electrical equipment of the kiln top structure of the gas-fired lime shaft kiln.

In order to protect kiln top structure equipment and process airflow control of the gas-fired lime shaft kiln, a combined frustum prefabricated block is mostly adopted in the kiln top structure of the existing gas-fired lime shaft kiln, as shown in fig. 1 and fig. 2, a frustum structure 110 is formed by enclosing 6 combined prefabricated pieces 111 with single piece weight of about 800kg, the outer side of the frustum structure 110 is limited by supporting outer legs 120 to move, a central chimney 100 for guiding flue gas made of heat-resistant steel is arranged in the center of the frustum structure 110, so that the hot flue gas is intensively guided and discharged from the central chimney, in the practical use process, the arrangement mode is found to easily cause the prefabricated pieces to be cracked and damaged, a gap 150 of more than 50mm is extruded between the prefabricated pieces and the central chimney, the hot flue gas containing dust is ejected from the kiln top structure 10a of the gas-fired lime shaft kiln to cause high-temperature roasting and deformation damage to the equipment arranged on the kiln top structure 10a of the gas-fired lime shaft kiln, meanwhile, hot smoke is easy to escape and fly away instantly when feeding.

Disclosure of Invention

It is an object of embodiments of the present application to provide a roof structure of a gas-fired lime shaft kiln and a construction method thereof, which can improve at least one of the above-mentioned technical problems.

In a first aspect, an embodiment of the present application provides a construction method for a kiln top structure of a gas-fired lime shaft kiln, which includes the following steps:

obtaining a plurality of fan-shaped first precast blocks, wherein the thickness of the first precast blocks is 170-.

And obtaining at least two groups of prefabricated blocks, wherein each group of prefabricated blocks comprises two fan-shaped second prefabricated blocks, the thickness, the top arc length and the bottom arc length of each second prefabricated block are the same as those of the first prefabricated block, the weight of each second prefabricated block is smaller than that of the first prefabricated block and not smaller than 550kg, and semicircular holes with the radius of 280-320mm for forming a smoke outlet are formed in one adjacent side edge of each second prefabricated block.

The method comprises the following steps of hoisting a plurality of first prefabricated blocks and prefabricated blocks to the circumferential direction of a central chimney and to be lower than a feeding port of the central chimney respectively, splicing the plurality of first prefabricated blocks and the plurality of prefabricated blocks at the top end of a kiln body of the gas-calcined lime shaft kiln to form a frustum structure surrounding the circumferential direction of the central chimney, butting two semicircular holes of each group of prefabricated blocks to form a circular smoke exhaust port, and then binding and hooping by adopting steel belts. The central chimney is blocked and extends out of the frustum structure and is higher than one end of the feed inlet.

In the above-mentioned realization process, at first, adopt specific radius's semicircle orifice and set up in the specific mode of setting of the side of second prefabricated section, combine the cooperation of specific thickness, top arc length, bottom arc length and weight, not only can smoothly discharge fume, even on the frustum structure had the basis of exhaust port, also can avoid the decline of the intensity of frustum structure simultaneously, avoid first prefabricated section and second prefabricated section to be damaged in the in-service use process and influence the gas tightness. Secondly, the smoke outlet is moved downwards to the frustum structure after construction is completed, and the smoke outlet and the feeding port are arranged in a staggered mode, so that hot smoke is prevented from escaping and flying dust instantly when the feeding port is opened, the kiln top structure of the gas-calcined lime shaft kiln is low in temperature, equipment outside the kiln top structure of the gas-calcined lime shaft kiln is protected from being roasted for a long time at high temperature, expansion and outward extrusion of a central chimney are avoided, and the frustum structure is stable and tightly attached to the central chimney. Finally, the hot smoke is led out from the frustum structure at the low position, and the cross-sectional area of the frustum structure is larger than that of the central chimney, so that the high position of the central chimney is ensured to be in a negative pressure state when the charging opening is opened, stone added from the charging opening cannot be in reverse flowing contact with the smoke below, and the hot smoke is further prevented from escaping and floating dust instantly when charging.

That is, the installation mode can make the kiln top structure of the gas-calcined lime shaft kiln under the condition of being in high-temperature hot flue gas, can prolong the service life of refractory materials of the kiln top structure of the gas-calcined lime shaft kiln, ensures that the kiln top structure of the gas-calcined lime shaft kiln does not leak dust, and ensures that equipment installed on the kiln top structure of the gas-calcined lime shaft kiln runs stably.

In a second aspect, the embodiment of the application provides a kiln crown structure of a gas-fired lime shaft kiln, the kiln crown structure of the gas-fired lime shaft kiln comprises a central chimney and a frustum structure, the central chimney is provided with a feed inlet and a material door for sealing the feed inlet, the feed inlet is positioned outside the frustum structure, the end part of one end of the frustum structure, extending out of the central chimney, is sealed, the frustum structure is arranged on the top end of a kiln body of the gas-fired lime shaft kiln and is enclosed in the central chimney, and the frustum structure is provided with at least two smoke exhaust ports for outputting smoke.

The frustum structure is formed by splicing a plurality of fan-shaped first precast blocks and at least two groups of precast blocks, wherein the thickness of the first precast blocks is 230mm, the top arc length is 650mm, the bottom arc length is 1300 mm and 1400mm, and the weight is larger than 550kg and not more than 650 kg.

The prefabricated block comprises two fan-shaped second prefabricated blocks, the thickness, the top arc length and the bottom arc length of the second prefabricated block are the same as those of the first prefabricated block, the weight of the second prefabricated block is smaller than that of the first prefabricated block and is not smaller than 550kg, semicircular holes which form the smoke exhaust port and have the radius of 280 plus 320mm are formed in one side edge of each of the two adjacent second prefabricated blocks, and the two semicircular holes of each group of prefabricated blocks are butted to form a circular smoke exhaust port.

In the implementation process, the smoke outlet for outputting smoke is moved downwards to the frustum structure, so that the projection position of the feeding port and the smoke outlet are arranged in a staggered mode, hot smoke is prevented from escaping and flying dust instantly when the material door is opened, meanwhile, the temperature of the kiln top structure of the gas-calcined lime shaft kiln is low, equipment outside the kiln top structure of the gas-calcined lime shaft kiln is protected from being roasted for a long time by high temperature, the expansion and outward extrusion of a central chimney are avoided, and the frustum structure is stable and tightly attached to the central chimney tightly. Meanwhile, hot smoke is led out from the frustum structure at a low position, and the cross-sectional area of the frustum structure is larger than that of the central chimney, so that the high position of the central chimney is ensured to be in a negative pressure state when the charging opening is opened, stone added from the charging opening cannot be in reverse flowing contact with smoke below, and the hot smoke is further prevented from escaping and floating dust instantly when charging.

Meanwhile, the semicircular holes with specific radius and the arrangement mode of the semicircular holes arranged on the side edge of the second precast block are combined with the specific thickness, the top arc length, the bottom arc length and the weight, so that the strength of the frustum structure can be prevented from being reduced on the basis that the frustum structure has a smoke exhaust port, and the influence on air tightness caused by the fact that the first precast block and the second precast block are damaged in the actual use process is avoided.

In conclusion, the kiln top structure of the gas-calcined lime shaft kiln can prolong the service life of refractory materials of the kiln top structure of the gas-calcined lime shaft kiln under the condition of high-temperature hot flue gas, avoid leakage and dust emission and simultaneously ensure the stable operation of equipment installed on the kiln top structure of the gas-calcined lime shaft kiln.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

FIG. 1 is a schematic sectional view of a roof structure 10a of a gas-fired lime shaft kiln after use;

FIG. 2 is a top view of the crown structure 10a of the gas-fired lime shaft kiln after use;

FIG. 3 is a schematic sectional view of a crown structure 10b of the gas-fired lime shaft kiln;

FIG. 4 is a top view of a crown structure 10b of the gas-fired lime shaft kiln;

fig. 5 is a top view of a second preform block.

Icon: 10 a-a kiln top structure of a gas-fired lime shaft kiln; 10 b-a kiln top structure of a gas-burning lime shaft kiln; 100-central chimney; 110-frustum structure; 111-a preform; 113-a first preform block; 114-prefabricated chunks; 115-a second preform block; 1151-top arc length; 1153-bottom arc length; 1155-side; 1156-semicircular holes; 116-a sling; 117-smoke outlet; 120-support outer leg; 130-a feed inlet; 131-a bin gate; 140-a kiln body; 150-gap.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

The terms "first," "second," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

The kiln top structure 10a of the gas-calcined lime shaft kiln shown in figure 1 is adopted, wherein the arrow direction is the smoke exhaust direction, in the process of conducting the concentrated drainage and the outward discharge of hot smoke from the central chimney 100 by adopting the kiln top structure 10a of the gas-calcined lime shaft kiln, the applicant finds that, on one hand, the kiln top structure 10a of the gas-fired lime shaft kiln has certain process defects, the central chimney 100 is fed and drawn with flue gas, the temperature of hot flue gas is higher, at 350-650 ℃, the temperature is about 700 ℃ when the kiln conditions are abnormal, the central chimney 100 is heated and expanded due to high temperature, the expansion stress extrudes the peripheral prefabricated member 111 refractory outwards to cause the prefabricated member 111 to be cracked and damaged, and a gap 150 shown in fig. 2 is extruded between the central chimney 100 and the gas-fired lime shaft kiln top structure 10a, so that hot flue gas containing dust is ejected from the gas-fired lime shaft kiln top structure 10a, and deformation and damage are caused by high-temperature roasting on the gas-fired lime shaft kiln top structure 10a equipment. On the other hand, the charging is carried out from the side of the central chimney 100 of the kiln top structure 10a of the gas-fired lime shaft kiln, and the hot flue gas is often caused to instantly escape from the charging hole 130 due to the opening of the charging door 131 of the central chimney 100 during the charging.

In view of this, the present application is hereby presented.

A construction method of a kiln top structure of a gas-fired lime shaft kiln comprises the following steps:

and S1, obtaining a plurality of fan-shaped first precast blocks.

The thickness of the first precast block is 170-230mm, the top arc length is 600-650mm, the bottom arc length is 1300-1400mm, and the weight is larger than 550kg and not larger than 650 kg.

The number of the first prefabricated section may be two, three, five, etc., and is not limited herein.

And S2, obtaining at least two groups of prefabricated blocks.

The number of the prefabricated blocks can be two or three, etc., and is not limited herein.

Wherein, every group prefabricated section piece includes the second prefabricated section of fan-shaped, and the thickness, top arc length, the bottom arc length homogeneous phase of second prefabricated section and first prefabricated section are convenient for splice and form the frustum structure, guarantee the intensity of frustum structure simultaneously.

Any side edge of the second prefabricated block is provided with a semicircular hole which forms a smoke exhaust port and has a radius of 280-320mm, the weight of the second prefabricated block is smaller than that of the first prefabricated block and is not smaller than 550kg, namely, the semicircular hole is formed in the second prefabricated block, so that the weight of the second prefabricated block is smaller than that of the first prefabricated block, the semicircular hole is formed in the side edge, the semicircular hole with the specific radius and the specific size of the second prefabricated block are matched with each other, and the strength of the second prefabricated block and the strength of the spliced frustum structure are effectively prevented from being influenced.

Compared with the existing weight of 800kg, the first precast block and the second precast block with specific weights are more beneficial to hoisting, and the construction difficulty is reduced.

In order to improve the stability of the frustum structure, optionally, each set of prefabricated blocks includes two second prefabricated blocks, and a semicircular hole with a radius of 280 and 320mm for forming a smoke exhaust port is formed in one adjacent side edge of each second prefabricated block. Under the condition, the step of splicing the plurality of first precast blocks and the precast blocks to form the frustum structure surrounding the circumference of the central chimney comprises the following steps of: two semicircular holes of two second prefabricated blocks of each group of prefabricated blocks are butted to form a circular hole as a smoke exhaust port, namely, the smoke exhaust port at the moment is a circular smoke exhaust port with the radius of 300 mm.

It should be noted that, the first precast block and the second precast block are made of the same material, so as to ensure the strength of the frustum structure.

Optionally, the first precast block and the second precast block are both manufactured by the following method:

mixing the raw materials, pouring, vibrating, molding, curing at room temperature, and baking at 150 ℃ for 20-28h to obtain the product.

Wherein, the mixing can be performed by stirring, for example, stirring for 5-10min to uniformly mix the raw materials, the pouring vibration molding can be performed by pouring the mixed raw materials into a mold, and then pouring vibration molding is performed on a vibration table or by means of a vibration rod, which is not limited herein, and the room temperature curing includes: and curing the prefabricated block subjected to vibration molding and the mold for 24 hours at room temperature, demolding, and curing for 24 hours at room temperature.

The raw materials comprise: mixing materials, a water reducing agent and water.

Wherein the addition amount of the water reducing agent is 0.10-0.25 wt% of the mixture, and the addition amount of the water is 5.0-6.5 wt% of the mixture; the mixed material comprises 75-90 wt% of bauxite chamotte, 3-15 wt% of kyanite fine powder, 1-10 wt% of alumina micro powder, 0-10 wt% of aluminate cement and 1-5 wt% of silicon-aluminum gel. The raw materials are reasonable in proportion, and meanwhile, the obtained first prefabricated block and the second prefabricated block are high in strength and good in heat insulation effect by combining a specific preparation process.

Because the first precast block and the second precast block are installed in the actual installation process in a hoisting mode, optionally, the construction method further comprises embedding hoisting pieces in the first precast block and the second precast block respectively, wherein the hoisting pieces are symmetrically arranged along a central connecting line of the top arc length and the bottom arc length, and the hoisting pieces are located at 2/3 of the length of the central connecting line and are offset to one end close to the top arc length. The position is convenient for hoist and mount, and the stability of first prefabricated section with the second prefabricated section in the hoist and mount process also can be guaranteed simultaneously to the aforesaid, improves the precision of installation back concatenation, guarantees that the leakproofness is good.

S3, hoisting the plurality of first prefabricated blocks and the plurality of prefabricated blocks to the circumferential direction of the central chimney and to be lower than the feeding port of the central chimney respectively, splicing the plurality of first prefabricated blocks and the plurality of prefabricated blocks at the top end of the kiln body of the gas-fired lime shaft kiln to form a frustum structure surrounding the circumferential direction of the central chimney, butting two semicircular holes of each group of prefabricated blocks to form a circular smoke exhaust port, and then binding and hooping by adopting steel belts.

Optionally, the step of splicing the plurality of first precast blocks and the plurality of precast blocks to form a frustum structure surrounding the circumference of the central chimney includes: the at least two smoke outlets are indirectly arranged along the circumferential direction of the frustum structure at equal intervals, so that the frustum structure can be stressed uniformly, and the stability of the frustum structure is improved.

Optionally, the step of splicing the plurality of first precast blocks and the plurality of precast blocks to form a frustum structure surrounding the circumference of the central chimney includes: the smoke outlet is symmetrical along the axis of the central chimney, so that the smoke discharging efficiency is good.

Optionally, when the number of the first precast blocks is four, the number of the precast blocks is two, and each precast block includes two second precast blocks, the step of hoisting the plurality of first precast blocks and the plurality of precast blocks to the circumferential direction of the central chimney respectively includes: hoisting and enclosing in the circumferential direction of a central chimney in sequence according to the modes of two first precast blocks, one precast block, two first precast blocks and one precast block, then adopting a steel belt to enclose and tie tightly, ensuring that the frustum structure is stably arranged at the top end of the kiln body and connected with the central chimney so as to seal the top end of the kiln body and discharge hot flue gas along a preset flue gas port.

Wherein, the steel belt can adopt a flat steel belt with the width of 150 mm.

In order to avoid that the hot smoke may affect the expansion of the semicircular section of the second precast block due to the high heat of the hot smoke, the construction method optionally further comprises: after the steel band is tightly bound and hooped, a heat-resistant steel pipe is arranged in the circular smoke exhaust port.

S4, blocking one end of the central chimney, which extends out of the frustum structure and is higher than the feed inlet. So that the hot smoke can only be discharged from the smoke outlet.

The structure of the top of the gas-fired lime shaft kiln and the construction method thereof will be described in further detail with reference to examples.

Example 1

Referring to fig. 3 and 4, a kiln top structure 10b of a gas-fired lime shaft kiln includes a central chimney 100 and a frustum structure 110.

The central chimney 100 is provided with a feed inlet 130 and a material door 131 for sealing the feed inlet 130, the feed inlet 130 is positioned outside the frustum structure 110, the end part of the central chimney 100 extending out of one end of the frustum structure 110 is sealed, and the frustum structure 110 is arranged at the top end of a kiln body 140 of the gas-fired lime shaft kiln and is surrounded on the central chimney 100.

Optionally, the kiln top structure 10b of the gas-fired lime shaft kiln comprises a supporting outer leg 120, the supporting outer leg 120 is arranged around the outer edge of the top end of the kiln body 140, the top end of the frustum structure 110 is arranged around and delivered to the outer wall of the central chimney 100, the bottom end of the frustum structure 110 is connected with the top end of the kiln body 140 and is located on the inner side of the supporting outer leg 120, and the supporting outer leg 120 is matched with the central chimney 100 to limit the movement of the frustum structure 110.

The frustum structure 110 is provided with a smoke exhaust 117, wherein the direction of the arrow shown in fig. 3 is a smoke exhaust direction.

Wherein the number of the smoke discharge openings 117 is at least two, such as two, three or four, and the like, wherein all the smoke discharge openings 117 are arranged at equal intervals along the circumferential direction of the frustum structure 110. In this embodiment, the number of the smoke discharge ports 117 is two, and the two smoke discharge ports 117 are symmetrically arranged along the axis of the central chimney 100.

Optionally, a heat-resistant steel pipe is installed in each smoke outlet 117, and the radius of the inner wall of the heat-resistant steel pipe is 285 mm.

The frustum structure 110 is formed by splicing a plurality of fan-shaped first precast blocks 113, specifically, two, three or four precast blocks 113, and at least two groups, specifically, two groups, three groups or the like of precast blocks 114, where each group of precast blocks 114 includes two second precast blocks 115.

In this embodiment, the frustum structure 110 is formed by splicing four fan-shaped first prefabricated blocks 113 and two prefabricated blocks 114.

Referring to fig. 4 and 5, the first prefabricated section 113 has a thickness of 200mm, a top arc length 1151 of 600mm, a bottom arc length 1153 of 1400mm, and a weight of 600 kg. Each set of precast blocks 114 includes two second precast blocks 115, and each second precast block 115 has the same thickness, top arc length 1151 and bottom arc length 1153 as the first precast block 113, that is, the frustum structure 110 is formed by splicing four equally-divided first precast blocks 113 and four second precast blocks 115. Wherein, one side 1155 of two adjacent second precast blocks 115 of each set of precast blocks 114 is provided with a semicircular hole 1156 with a radius of 280-320mm, for example 300mm, and the two semicircular holes 1156 of the two second precast blocks 115 are butted to form a circular smoke outlet 117.

The first precast block 113 and the second precast block 115 are made of the same material, and the first precast block 113 and the second precast block 115 are both made by the following method:

the raw materials are stirred and mixed uniformly, after pouring and vibration forming, the prefabricated block after vibration forming and a mould are maintained for 24 hours at room temperature, then demoulding is carried out, maintenance is carried out for 24 hours at room temperature, and then baking is carried out for 24 hours at the temperature of 100 plus materials and 150 degrees to obtain the finished product.

Wherein, the raw materials include: the water reducer is added in an amount of 0.2 wt% of the mixture, and the water is added in an amount of 5.5 wt% of the mixture. The mixed material comprises 80 wt% of bauxite chamotte, 10 wt% of kyanite fine powder, 5 wt% of alumina micro powder, 3 wt% of aluminate cement and 2 wt% of silica-alumina gel according to mass percentage.

Optionally, each of the first prefabricated block 113 and the second prefabricated block 115 is provided with a sling 116, wherein the sling 116 is symmetrically arranged along a central connecting line of a top arc length 1151 and a bottom arc length 1153 of the corresponding first prefabricated block 113 or the corresponding second prefabricated block 115, and the sling 116 is located at 2/3 of the central connecting line and is offset from one end close to the top arc length 1151.

Specifically, hoist and mount piece 116 includes the hexagonal nut of the M20 of two symmetry settings to and a length is the 20 mm's of diameter round steel of 100mm, and the one end pre-buried first prefabricated section 113 or the second prefabricated section 115 that correspond of two hexagonal nuts, the other end of two hexagonal nuts respectively with the round steel welding.

After the kiln top structure 10a of the gas-calcined lime shaft kiln provided by the embodiment is used for 6 months, although the temperature is experienced when the kiln conditions are abnormal during the trial period, no gap 150 is formed between the frustum structure 110 of the kiln top structure 10a of the gas-calcined lime shaft kiln and the central chimney 100, and the air tightness of the connection is good and is better than that of the scheme shown in fig. 1.

The embodiment also provides a construction method of the kiln top structure 10a of the gas-fired lime shaft kiln, which comprises the following steps:

(1) the method comprises the steps of removing fillers and gravels at the top end of a kiln body 140 of the gas-fired lime shaft kiln, completely exposing a central chimney 100, arranging a supporting outer leg 120 at the top end of the kiln body 140 and enabling the supporting outer leg 120 to surround the outer edge of the top end of the kiln body 140.

(2) Four first precast blocks 113 and two precast blocks 114 in a fan shape are obtained, each precast block 114 including two second precast blocks 115. Sequentially hoisting and enclosing the two first precast blocks 113, the precast block 114, the two first precast blocks 113 and the precast block 114 in the circumferential direction of the central chimney 100, butting two semicircular holes 1156 of the two precast blocks of each precast block 114 to form a circular smoke outlet 117, and then enclosing and hooping by adopting a flat steel band with the width of 150mm to ensure that the frustum structure 110 is stably arranged at the top end of the kiln body 140 and connected with the central chimney 100 so as to seal the top end of the kiln body 140 and discharge hot smoke along the preset smoke outlet 117.

(3) A heat-resistant steel pipe is arranged in the circular hole, and one end of the central chimney 100, which extends out of the frustum structure 110 and is higher than the feed inlet 130, is blocked.

The construction method provided by the application is simple, the kiln top structure of the gas-calcined lime shaft kiln obtained by construction is good in sealing performance, and the frustum structure and the chimney are tightly attached; the hot flue gas is led out through the low-position frustum structure, so that when the charging opening is opened, the high position of the central chimney where the charging opening is positioned is in a negative pressure state, and the stone and the hot flue gas are not in reverse flowing contact any more; meanwhile, hot flue gas is led out from the frustum structure instead, so that the temperature of the kiln top structure of the gas-fired lime shaft kiln is lower, and equipment outside the kiln top structure of the gas-fired lime shaft kiln is protected from being roasted at high temperature for a long time; the service life of the kiln top structure of the gas-calcined lime shaft kiln under high-temperature hot flue gas is prolonged, the kiln top structure of the gas-calcined lime shaft kiln is guaranteed not to leak dust, and stable production operation of equipment installed on the kiln top structure of the gas-calcined lime shaft kiln is guaranteed.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.