A vertical kiln and its combustion method

Abstract

The present invention relates to the technical field of refractory materials, and specifically relates to a vertical kiln and a combustion method. By adjusting the vertical kiln in the shape of a frustum with a smaller top and a larger bottom, similar to a chimney, to be composed of two frustum shapes, where one frustum is inverted above the other, that is, by inverting the existing preheating zone and increasing the volume to a certain extent, it is possible to increase the stock storage and extend the residence time in the preheating zone, making full use of the preheating of the furnace and reducing the heat consumption to a certain extent. By replacing the existing integral wall surface with a structure composed of three side walls and gaps, since gaps are provided between the three side walls, there is sufficient space to release stress when it expands due to heat, reducing the probability of overall deformation of the kiln. At the same time, the specific heat capacity of air is higher than that of bricks, enabling it to absorb more heat, thereby increasing the heat insulation effect to a certain extent.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, and specifically relates to a vertical kiln. Background Art

[0002] The shaft kiln is also known as a vertical kiln. As shown in, the existing shaft kilns are mostly chimney structures, which are frustum-shaped with a smaller upper part and a larger lower part. The top is the preheating zone, the middle is the high-temperature zone, and the bottom is the cooling zone. Due to the overall frustum-shaped structure, the raw materials usually stay in the preheating zone for 20 hours, which is too short. And if it is necessary to extend the residence time in the preheating zone, the height of the vertical kiln needs to be further increased, greatly increasing the cost. At the same time, as shown in, the existing kilns mostly use integral walls, and adjacent walls are connected by fillers. After changing from coal to natural gas as fuel, in order to improve the heat preservation effect, the overall thickness of the wall increases. As the wall thickens, the expansion coefficient also increases, and problems such as kiln wall deformation, fire leakage, gas leakage, and air leakage are likely to occur during long-term use. And when burning, natural gas and air are usually mixed and ignited in the combustion channel to form a flame. During transportation, part of the heat is absorbed by the kiln wall, and if the operation is improper, fire leakage and gas leakage are likely to occur. Figure 1 shown, the existing shaft kilns are mostly chimney structures, which are frustum-shaped with a smaller upper part and a larger lower part. The top is the preheating zone, the middle is the high-temperature zone, and the bottom is the cooling zone. Due to the overall frustum-shaped structure, the raw materials usually stay in the preheating zone for 20 hours, which is too short. And if it is necessary to extend the residence time in the preheating zone, the height of the vertical kiln needs to be further increased, greatly increasing the cost. At the same time, as shown in, the existing kilns mostly use integral walls, and adjacent walls are connected by fillers. After changing from coal to natural gas as fuel, in order to improve the heat preservation effect, the overall thickness of the wall increases. As the wall thickens, the expansion coefficient also increases, and problems such as kiln wall deformation, fire leakage, gas leakage, and air leakage are likely to occur during long-term use. And when burning, natural gas and air are usually mixed and ignited in the combustion channel to form a flame. During transportation, part of the heat is absorbed by the kiln wall, and if the operation is improper, fire leakage and gas leakage are likely to occur. Figure 4 shown, the existing kilns mostly use integral walls, and adjacent walls are connected by fillers. After changing from coal to natural gas as fuel, in order to improve the heat preservation effect, the overall thickness of the wall increases. As the wall thickens, the expansion coefficient also increases, and problems such as kiln wall deformation, fire leakage, gas leakage, and air leakage are likely to occur during long-term use. And when burning, natural gas and air are usually mixed and ignited in the combustion channel to form a flame. During transportation, part of the heat is absorbed by the kiln wall, and if the operation is improper, fire leakage and gas leakage are likely to occur.

[0003] And the combustion flame is input to the high-temperature zone through a high-pressure blower. Since the product shrinks greatly in the high-temperature zone and the ventilation condition is not ideal, it is difficult for the flame to flow smoothly upward. Coupled with the pressure of the high-pressure blower, the positive pressure in this area increases, and the flame moves towards the lower cooling zone, resulting in a slower cooling speed. When the material is discharged from the cooling zone during use, the temperature is still about 600 °C, which not only increases the working environment temperature but also causes a large amount of heat energy waste. Summary of the Invention

[0004] The present invention aims at the above problems and provides a vertical kiln.

[0005] The technical solution adopted is that a vertical kiln includes a furnace body, which is provided with a preheating zone, a high-temperature zone, and a cooling zone from top to bottom. The furnace body is composed of walls. The high-temperature zone and the cooling zone are frustum-shaped structures, and the upper part of the frustum is the small-end and the lower part of the frustum is the large-end. The wall is composed of multiple walls arranged side by side. Among them, the preheating zone is a frustum-shaped structure, and the upper part of the preheating zone is the large-end and the lower part of the preheating zone is the small-end. And the lower part of the preheating zone is communicated with the upper part of the high-temperature zone. A heat utilization device is arranged outside the furnace body of the kiln. The heat utilization device includes a blower and a wind guide pipe. And the blower guides the gas in the cooling zone into the high-temperature zone through the wind guide pipe. The furnace wall includes a first wall, a second wall, and a third wall. The first wall is close to the inner side of the vertical kiln, the third wall is close to the outer side of the vertical kiln, the second wall is located between the first wall and the third wall, and there are gaps between the second wall and the first wall and the third wall respectively.

[0006] Optionally, the heights of the preheating zone, the high-temperature zone, and the cooling zone are equal, and the heights of the preheating zone, the high-temperature zone, and the cooling zone are all 10 m.

[0007] Optionally, a combustion surface is further provided at the lower part of the preheating zone, and the combustion surface is in the shape of a frustum of a cone. The lower part of the combustion surface is the small-head end and is communicated with the upper part of the high-temperature zone. The height of the combustion surface is 2 m.

[0008] Furthermore, the size of the big-head end of the preheating zone is larger than that of the big-head end of the cooling zone, and the ratio is 4:3.

[0009] Optionally, the heights of the preheating zone, the high-temperature zone, and the cooling zone are all 10 m. A second connection terminal is provided at 8 m above the ground in the cooling zone, and a first connection terminal is provided at 19 m above the ground in the high-temperature zone. The air duct is communicated with the first connection terminal and the second connection terminal respectively.

[0010] Optionally, the outer periphery of the air duct is wrapped with a heat-insulating cotton layer.

[0011] Furthermore, a natural gas supply pipeline is also communicated with the high-temperature zone, and the connection part of the natural gas supply pipeline and the high-temperature zone is located below the combustion surface.

[0012] Optionally, there is a first gap between the second wall and the first wall, and a second gap between the second wall and the third wall. The first gaps in the left and right adjacent walls are communicated with each other, and the second gaps in the left and right adjacent walls are also communicated with each other. And in the upper and lower adjacent walls, the first gap and the second gap are arranged in a staggered manner.

[0013] Optionally, the wall body includes a first type of wall surface and a second type of wall surface. The sizes of the first wall, the second wall, and the third wall in the first type of wall surface are the same. The sizes of the first wall and the third wall in the second type of wall surface are the same, and the size of the second wall is smaller than those of the first wall and the third wall. The vertical projection of the first gap in the first type of wall surface is located outside the vertical projection of the first gap in the second type of wall surface, and the vertical projection of the second gap in the first type of wall surface is located outside the vertical projection of the second gap in the second type of wall surface.

[0014] The present invention also provides a combustion method applicable to a vertical kiln, including the following steps:

[0015] S. Inject air into the furnace from the conveying pipe in the cooling zone at the bottom of the furnace body;

[0016] S. Inject natural gas into the furnace from the natural gas supply pipeline in the middle of the furnace body;

[0017] S. Burn the mixture of natural gas and air in the high-temperature zone.

[0018] The beneficial effects of the present invention at least include one of the following;

[0019] 1. By adjusting the vertical kiln furnace in the shape of a frustum of a cone with a smaller upper part and a larger lower part, which resembles a chimney, to be composed of two frustum shapes, where one frustum is inverted above the other, that is, by inverting the existing preheating zone, and increasing the volume to a certain extent, it is possible to increase the stock storage and extend the residence time in the preheating zone, making full use of the preheating of the furnace and reducing heat consumption to a certain extent.

[0020] 2. At the same time, as the residence time of the stock in the preheating zone increases, the stock is preheated for sufficient time, slowly heating up and not easily cracking, and the shape of the stock is not easily damaged. Moreover, as the preheating time increases, the natural water, structural water, and crystal water in the stock are more easily discharged, so when entering the high-temperature zone, water vapor is not easily generated, thus ensuring a relatively high temperature in the high-temperature zone.

[0021] 3. By replacing the existing integral wall surface with a structure composed of three wall surfaces and gaps, since gaps are provided between the three wall surfaces, when it expands due to heat, there is sufficient space to release stress, reducing the probability of overall deformation of the kiln furnace. At the same time, the specific heat capacity of air is higher than that of bricks, enabling it to absorb more heat, thereby increasing the heat preservation effect to a certain extent.

[0022] 4. By using a fan to extract the hot air in the cooling zone and send it to the high-temperature zone, since the entire furnace body is ventilated from the bottom, the overall air flow rate at the bottom is relatively large. When it is introduced into the high-temperature zone, the product will not carry away the temperature, achieving heat utilization to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the structure of the existing vertical kiln furnace;

[0024] Figure 2 is a schematic diagram of the structure of a vertical kiln furnace;

[0025] Figure 3 is a schematic diagram of the natural gas supply pipeline and the vertical kiln furnace structure;

[0026] Figure 4 is a schematic diagram of the existing wall structure;

[0027] Figure 5 is a schematic diagram of the heat expansion prevention kiln wall structure;

[0028] Figure 6 is a schematic diagram of another heat expansion prevention kiln wall structure;

[0029] Figure 7 is a schematic diagram of the upper and lower layer structure of the heat expansion prevention kiln wall;

[0030] The markings in the figure are as follows: 1 is the furnace body, 2 is the cooling zone, 3 is the high-temperature zone, 4 is the preheating zone, 5 is the combustion surface, 6 is the blower, 7 is the first connection terminal, 8 is the second connection terminal, 9 is the gas transmission joint, 10 is the gas transmission pipe, 11 is the natural gas supply pipeline, 12 is the wall surface, 13 is the first wall, 14 is the second wall, 15 is the third wall, 16 is the first gap, 17 is the second gap, and 20 is the thermal insulation cotton. Specific Embodiment

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the protection scope of the present invention.

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention; terms such as "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, unless otherwise clearly specified and limited, the terms "installation", "connection" and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0033] As Figure 2 and Figure 3 shown, a vertical kiln includes a furnace body 1. The furnace body 1 is provided with a preheating zone 4, a high-temperature zone 3 and a cooling zone 2 from top to bottom. The furnace body 1 is composed of a wall. The high-temperature zone 3 and the cooling zone 2 are in a frustum structure, and the upper part of the frustum is the small-end and the lower part is the large-end. The wall is composed of a plurality of wall surfaces 12 arranged side by side. Among them, the preheating zone 4 is in a frustum structure, and the upper part of the preheating zone 4 is the large-end and the lower part is the small-end. And the lower part of the preheating zone 4 is communicated with the upper part of the high-temperature zone 3. A heat utilization device is arranged outside the furnace body of the furnace body 1. The heat utilization device includes a blower 6 and a wind guide pipe. And the blower 6 introduces the gas in the cooling zone 2 into the high-temperature zone 3 through the wind guide pipe. The furnace wall surface includes a first wall 13, a second wall 14 and a third wall 15. And the first wall 13 is close to the inner side of the vertical kiln, the third wall 15 is close to the outer side of the vertical kiln, the second wall 14 is located between the first wall 13 and the third wall 15, and there are gaps between the second wall 14 and the first wall 13 and the third wall 15 respectively.

[0034] The purpose of this design is to adjust the vertical kiln in the shape of a frustum with a smaller upper part and a larger lower part, like a chimney, into a structure composed of two frustum shapes, where one frustum is inverted above the other, that is, to invert the existing preheating zone, and to increase the volume to a certain extent, so as to increase the stock storage and extend the residence time in the preheating zone, making full use of the preheating of the furnace, and reducing the heat consumption to a certain extent. At the same time, as the residence time of the stock in the preheating zone increases, the stock is preheated for sufficient time, slowly heated up and is not easy to crack, the shape of the stock is not easy to be damaged, and as the preheating time increases, the natural water, structural water and crystal water in the stock are more easily discharged, so when entering the high-temperature zone, it is not easy to generate water vapor, thus ensuring a higher temperature in the high-temperature zone. By replacing the existing integral wall surface with a structure composed of three side walls and gaps, since gaps are provided between the three side walls, when it expands due to heat, there is enough space to release stress, reducing the probability of the overall deformation of the kiln. At the same time, the specific heat capacity of air is higher than that of bricks, so it can absorb more heat, thus increasing the heat preservation effect to a certain extent.

[0035] Taking the vertical kiln currently used by the applicant as an example, it has a cooling zone height of 10m, a high-temperature zone height of 10m and a preheating zone height of 10m, and the opening diameter of the preheating zone is 4m, the bottom diameter of the cooling zone is 3m, and the diameter of the middle combustion surface is 2m.

[0036] Taking a vertical kiln of the same height for comparison, the volume of the top preheating zone has increased by 3 - 4 times, and correspondingly, the raw materials that can be stored in the preheating zone have also increased by 3 - 4 times to a certain extent. The temperature at the combustion surface is close to 1450 degrees Celsius, and at this temperature, the stone does not agglomerate. The temperature gradually decreases upward in the preheating zone, and the temperature is around 100 degrees Celsius at the entrance of the top of the preheating zone.

[0037] Through comparative statistics, the residence time of the stock in the preheating zone of the existing vertical kiln is 20h. Due to the improvement in the structure in this embodiment, the diameter is increased, and the structure of an inverted frustum is adopted, so that the stock can stay in the preheating zone for up to 70h. As time increases, the preheating effect is fully improved.

[0038] It should be noted that the combustion surface referred to in this embodiment is not the actual combustion position, but is located above the combustion position. This area has a high temperature, and at the same time, the frustum structure is adopted. The lower part of the combustion surface is the small-head end and is connected to the upper part of the high-temperature zone, further reducing the port size of the preheating zone entering the high-temperature zone, making this area have heat accumulation, the temperature rises and is not easy to be lost.

[0039] Such as Figures 5 to 7As shown, there is a first gap 16 between the second wall 14 and the first wall 13, and a second gap 17 between the second wall 14 and the third wall 15. The first gaps 16 in the left and right adjacent walls 12 communicate with each other, and the second gaps 16 in the left and right adjacent walls 12 also communicate with each other. Among the upper and lower adjacent walls 12, the first gap 16 and the second gap 17 are arranged in a staggered manner.

[0040] In this way, the first gap and the second gap in the upper and lower walls are arranged in a staggered manner and do not communicate with each other, so that the kiln wall still maintains an integral connection relationship.

[0041] The specific way of the staggered arrangement is as Figure 5 shown. The wall body includes a first type of wall surface and a second type of wall surface, where Figure 3 for the first type of wall surface, the first wall 13, the second wall 14, and the third wall 15 have the same size. Among them, Figure 4 for the second type of wall surface, the first wall 13 and the third wall 15 have the same size, and the size of the second wall 14 is smaller than that of the first wall 13 and the third wall 15. In this way, the vertical projection of the first gap 16 in the first type of wall surface is located outside the vertical projection of the first gap 16 in the second type of wall surface, and the vertical projection of the second gap 17 in the first type of wall surface is located outside the vertical projection of the second gap 17 in the second type of wall surface.

[0042] When the first wall close to the inner side of the vertical kiln is heated and expands, the first gap provides sufficient space to cooperate with its expansion. Then the second wall is heated and expands, and finally the third wall. For the vertical kiln currently used by the applicant, the first gap and the second gap are 10 - 20 cm, usually 15 cm.

[0043] At the same time, it should be noted that during normal use, a filler is required to fill and connect between the wall surfaces. In this embodiment, the description of this is omitted, not that it is not used. It is just that the gap formed after filling and connecting is 10 - 20 cm.

[0044] It solves the problems that in order to improve the heat insulation effect of the existing kiln wall, the overall thickness of the wall surface increases, the wall surface thickens, and the expansion coefficient also increases. During long-term use, problems such as kiln wall deformation, fire leakage, air leakage, and air leakage are likely to occur. The specific heat capacity of air is higher than that of bricks, so that it can absorb more heat, thereby increasing the heat insulation effect to a certain extent.

[0045] At the same time, this embodiment also provides a combustion method for a vertical kiln, including the following steps:

[0046] S1. Inject air into the furnace from the delivery pipe 10 in the bottom cooling zone of the furnace body 1;

[0047] S2. Inject natural gas into the furnace from the natural gas supply pipeline 11 in the middle of the furnace body 1;

[0048] S3. The mixture of natural gas and air burns in the high-temperature zone 3.

[0049] Among them, the air inlet of the whole vertical kiln is arranged at the bottom and consists of a gas transmission joint and a gas transmission pipe. The gas transmission joint is communicated with the main gas transmission pipe, and the gas is introduced into the cooling zone through the gas transmission pipe.

[0050] Especially taking the vertical kiln currently in use in the application as an example, it has a cooling zone height of 10 m, a high-temperature zone height of 10 m, and a preheating zone height of 10 m. Then, a second connection terminal 8 is arranged at 8 m above the ground in the cooling zone 2, and a first connection terminal 7 is arranged at 19 m above the ground in the high-temperature zone 3. The air guide pipes are respectively communicated with the first connection terminal 7 and the second connection terminal 8.

[0051] In this way, the hot air at 8 m above the ground in the cooling zone is introduced into the high-temperature zone at 19 m above the ground, solving the problem of oxygen deficiency in this area. At the same time, the temperature of the discharged gas is between 400 °C and 450 °C. Since the area from 10 m to 19 m above the ground is the high-temperature zone, the lacking temperature is supplemented by the introduced gas.

[0052] It should be noted that the heat utilization referred to in this embodiment has multiple meanings, including waste heat utilization, heat efficiency improvement, and so on.

[0053] At the same time, the outer periphery of the air guide pipe is wrapped with a heat-insulating cotton layer 20.

[0054] The purpose of such a design is that by setting the heat-insulating cotton layer, the heat dissipated by the discharged gas can be further reduced, so as to conduct heat preservation.

[0055] A natural gas supply pipe 11 is also communicated with the high-temperature zone 3, and the connection part of the natural gas supply pipe 11 and the high-temperature zone 3 is located below the combustion surface 5.

[0056] The purpose of such a design is that by arranging multiple natural gas supply pipes on the high-temperature zone, since only natural gas is transported and no oxygen is transported, the natural gas will not burn in the pipeline due to the influence of high temperature. After entering the furnace body, affected by the upward flow of hot air, it will diffuse. At the same time, with the air introduced from the bottom air inlet, the air flow moves upward, and the oxygen in the air also moves upward, cooperating with the introduced natural gas for combustion, so as to increase the furnace temperature.

[0057] In this embodiment, mainly natural gas is introduced into the furnace body to improve combustion, and the gas in the cooling zone close to the high-temperature zone is introduced to the connection part between the high-temperature zone and the preheating zone, so that the overall temperature distribution in the high-temperature zone is uniform, realizing heat utilization.

[0058] Thus, the original combustion at the burner of the kiln wall is changed to that the entire high-temperature zone becomes a large combustion chamber for combustion and preheating of the combustion chamber. The overall combustion time is long and the combustion volume is increased.

[0059] After the above adjustments, the high-temperature operation at the discharge end of the vertical kiln is changed to low-temperature operation. At the same time, in some areas of Shanxi, China, an iron-sheet vertical kiln is used to raise the temperature to 1600 °C for raw material firing, with a gas consumption of 90 - 100 m³. However, when using the vertical kiln provided in this embodiment and selecting the same operating parameters and raw materials to be processed, only 45 m³ of natural gas is required for each ton of raw materials for processing, and the overall gas consumption is significantly reduced.

[0060] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A vertical kiln, comprising a furnace body (1). The furnace body (1) is provided with a preheating zone (4), a high-temperature zone (3), and a cooling zone (2) from top to bottom. The furnace body (1) is composed of a wall. The high-temperature zone (3) and the cooling zone (2) are in a frustum structure, and the upper part of the frustum is the small-end and the lower part of the frustum is the large-end. The wall is composed of a plurality of side-by-side arranged wall surfaces (12), and it is characterized in that: The preheating zone (4) has a frustum structure, with the upper part of the preheating zone (4) being the large-head end and the lower part being the small-head end. The lower part of the preheating zone (4) communicates with the upper part of the high-temperature zone (3). A heat utilization device is provided outside the furnace body (1) of the furnace. The heat utilization device includes a fan (6) and a wind guide pipe. The fan (6) introduces the gas in the cooling zone (2) into the high-temperature zone (3) through the wind guide pipe. The furnace wall surface includes a first wall surface (13), a second wall surface (14), and a third wall surface (15). The first wall surface (13) is close to the inner side of the vertical kiln. The third wall surface (15) is close to the outer side of the vertical kiln. The second wall surface (14) is located between the first wall surface (13) and the third wall surface (15), and there are gaps between the second wall surface (14) and the first wall surface (13) and the third wall surface (15) respectively.

2. The vertical kiln according to claim 1, characterized in that: The heights of the preheating zone (4), the high-temperature zone (3), and the cooling zone (2) are equal, and the heights of the preheating zone (4), the high-temperature zone (3), and the cooling zone (2) are all 10 m.

3. The vertical kiln according to claim 2, characterized in that: A combustion surface (5) is further provided at the lower part of the preheating zone (4). The combustion surface (5) has a frustum structure. The lower part of the combustion surface (5) is the small-head end and communicates with the upper part of the high-temperature zone (3). The height of the combustion surface (5) is 2 m.

4. The vertical kiln according to claim 3, characterized in that: The size of the large-head end of the preheating zone (4) is larger than that of the large-head end of the cooling zone (2), and the ratio is 4:

3.

5. A vertical kiln according to claim 4, characterized in that: The heights of the preheating zone (4), the high-temperature zone (3), and the cooling zone (2) are all 10 m. A second connection terminal (8) is provided at 8 m above the ground in the cooling zone (2), and a first connection terminal (7) is provided at 19 m above the ground in the high-temperature zone (3). The wind guide pipe communicates with the first connection terminal (7) and the second connection terminal (8) respectively.

6. The vertical kiln according to claim 5, wherein: The outer circumference of the wind guide pipe is wrapped with a heat-insulating cotton layer (20).

7. An upright kiln according to claim 6, characterized in that: A natural gas supply pipe (11) is also connected to the high-temperature zone (3), and the connection part of the natural gas supply pipe (11) and the high-temperature zone (3) is located below the combustion surface (5).

8. A vertical kiln according to claim 7, characterized in that: There is a first gap (16) between the second wall surface (14) and the first wall surface (13), and a second gap (17) between the second wall surface (14) and the third wall surface (15). The first gaps (16) in the left and right adjacent wall surfaces (12) communicate with each other, and the second gaps (17) in the left and right adjacent wall surfaces (12) also communicate with each other. In the upper and lower adjacent wall surfaces (12), the first gap (16) and the second gap (17) are arranged in a staggered manner.

9. The vertical kiln according to claim 8, wherein: The wall body includes a first type of wall surface and a second type of wall surface. The sizes of the first wall surface (13), the second wall surface (14), and the third wall surface (15) in the first type of wall surface are the same. The sizes of the first wall surface (13) and the third wall surface (15) in the second type of wall surface are the same, and the size of the second wall surface (14) is smaller than those of the first wall surface (13) and the third wall surface (15). The vertical projection of the first gap (16) in the first type of wall surface is located outside the vertical projection of the first gap (16) in the second type of wall surface. The vertical projection of the second gap (17) in the first type of wall surface is located outside the vertical projection of the second gap (17) in the second type of wall surface.

10. A combustion method using the vertical kiln according to any one of claims 1-9, comprising the following steps: S1. Inject air into the furnace from the conveying pipe (10) in the bottom cooling zone of the furnace body (1); S2. Inject natural gas into the furnace from the natural gas supply pipe (11) in the middle of the furnace body (1); S3. Burn the mixture of natural gas and air in the high-temperature zone (3).

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