A cascade kiln for automatically controlling the flow rate of combustion fumes

Abstract

The application discloses a step kiln capable of automatically controlling the flow rate of combustion flue gas and belongs to the technical field of kilns. The step kiln capable of automatically controlling the flow rate of combustion flue gas comprises a kiln body, wherein the kiln body is provided with a furnace cavity extending along a first direction in a length direction, the kiln body comprises a flue gas discharging area, a preheating area and a firing area which are sequentially arranged and communicated along the first direction, and the furnace cavity of the firing area, the furnace cavity of the preheating area and the furnace cavity of the flue gas discharging area sequentially increase in cross-sectional area. The application can automatically reduce the flow rate of combustion flue gas, is favorable for reducing the power performance requirement of a flue gas fan, saves energy, and solves the problems of excessive negative pressure of the flue gas discharging area and the preheating area, excessive positive pressure of the firing area, large cross-sectional temperature difference, increased energy consumption, easy cracking of a green body, low heat utilization rate and the like in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of kiln technology, and specifically relates to a stepped kiln with automatic control of combustion flue gas flow rate. Background Technology

[0002] Horizontal kilns (such as roller kilns and tunnel kilns) are structurally and functionally divided into a flue gas exhaust zone (used to exhaust combustion gases from the kiln), a preheating zone, a firing zone, and a cooling zone (subdivided into rapid cooling, slow cooling, and tail cooling zones). Along their length, they are formed by several modular frame units (e.g., 2.1 meters per section) creating a continuous firing channel. In existing kiln structures, the outer width and inner height of the flue gas exhaust zone are smaller than those of the preheating and firing zones. The preheating zone, the intermediate firing zone, and the high firing zone have roughly the same outer width, inner width, and inner height. This design not only reduces the thickness of the insulation layer in the low-temperature flue gas exhaust zone, decreasing material usage and lowering costs, but also maintains a relatively uniform channel area across the kiln's different zones.

[0003] When the kiln exceeds a certain length, a high-pressure, high-flow exhaust fan must be selected. Only by forcefully drawing out the exhaust gas can the pressure generated by the flue gas inside the kiln be balanced. This results in a situation where the negative pressure in the exhaust zone and preheating zone is very high, and the positive pressure in the firing zone is particularly high.

[0004] Excessive negative pressure can cause the following problems: ① The burner flame is immediately drawn towards the kiln head by the exhaust fan after being ejected, preventing the flame from reaching the center of the kiln, resulting in a large temperature difference across the kiln and a decrease in the firing quality of the ceramic products; ② Severe air leakage (i.e., indoor air flowing into the kiln from the kiln body holes or gaps) in the kiln's roller holes, observation holes, etc., will cause temperature differences, increase fuel consumption, and raise costs; ③ High temperature at the kiln head makes the ceramic blanks prone to cracking; ④ High exhaust temperature leads to high energy consumption; ⑤ High flue gas velocity and short heat exchange time with the ceramic blanks result in low heat utilization rate.

[0005] Excessive positive pressure can cause the following problems: ① Severe flame leakage from the kiln's roller holes, observation holes, and other openings (i.e., flames leaking out from the kiln's holes or gaps), leading to increased fuel consumption; ② High flame jet resistance from the burners, resulting in a large temperature difference across the kiln's cross-section; ③ Excessive heat dissipation from the walls, increasing energy consumption. Summary of the Invention

[0006] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a stepped kiln with automatic control of the combustion flue gas velocity, which can automatically reduce the velocity of the combustion flue gas, thereby reducing the power performance requirements of the exhaust fan, saving energy, and solving serious problems in the prior art such as excessive negative pressure in the exhaust and preheating zones, excessive positive pressure in the firing zone, and the resulting large cross-sectional temperature difference, increased energy consumption, easy cracking of the green body, and low heat utilization rate.

[0007] According to an embodiment of the present invention, a stepped kiln for automatically controlling the combustion flue gas velocity includes a kiln body, the kiln body having a furnace cavity extending along a first direction in the length direction, the kiln body including a flue gas exhaust zone, a preheating zone and a firing zone arranged sequentially and connected along the first direction, the furnace cavity of the firing zone, the furnace cavity of the preheating zone and the furnace cavity of the flue gas exhaust zone increasing in cross-sectional area sequentially.

[0008] The stepped kiln with automatic control of combustion flue gas velocity according to embodiments of the present invention has at least the following beneficial effects: When the kiln body is in operation, the combustion flue gas in the furnace cavity flows from the firing zone to the exhaust zone, and the flue gas volume increases cumulatively along the firing zone to the preheating zone. Therefore, by changing the size of the cross-sectional area of ​​the kiln body, the cross-sectional areas of the firing zone, the preheating zone, and the exhaust zone are gradually increased in sequence, so that the kiln cavity of the kiln body increases in a stepped manner from the firing zone to the exhaust zone, thereby automatically reducing the flue gas velocity in the kiln body, resulting in a small positive pressure in the firing zone and a small negative pressure in the preheating zone and the exhaust zone. This leads to a small exhaust fan power, a small cross-sectional temperature difference in the furnace cavity, good heat exchange effect, saving electricity and fuel, and making the green body less prone to cracking.

[0009] In some embodiments of the present invention, the firing zone includes a medium-temperature firing zone and a high-temperature firing zone, and the preheating zone, the medium-temperature firing zone and the high-temperature firing zone are arranged sequentially and connected along a first direction.

[0010] In some embodiments of the present invention, the furnace cavity of the high-temperature firing zone, the furnace cavity of the medium-temperature firing zone, and the furnace cavity of the preheating zone increase in cross-sectional area sequentially.

[0011] In some embodiments of the present invention, the furnace cavity of the high-temperature firing zone, the furnace cavity of the medium-temperature firing zone, the furnace cavity of the preheating zone, and the furnace cavity of the flue gas exhaust zone increase in size sequentially in terms of inner width.

[0012] In some embodiments of the present invention, the furnace cavity of the high-temperature firing zone, the furnace cavity of the medium-temperature firing zone, the furnace cavity of the preheating zone, and the furnace cavity of the flue gas zone increase in size sequentially in an arithmetic progression.

[0013] In some embodiments of the present invention, the kiln walls on opposite sides of the high-temperature firing zone are of equal thickness, the kiln walls on opposite sides of the medium-temperature firing zone are of equal thickness, the kiln walls on opposite sides of the preheating zone are of equal thickness, and the kiln walls on opposite sides of the flue gas exhaust zone are of equal thickness.

[0014] In some embodiments of the present invention, the furnace cavity of the high-temperature firing zone, the furnace cavity of the medium-temperature firing zone, the furnace cavity of the preheating zone, and the furnace cavity of the flue gas exhaust zone increase in height sequentially.

[0015] In some embodiments of the present invention, the furnace cavity of the high-temperature firing zone, the furnace cavity of the medium-temperature firing zone, the furnace cavity of the preheating zone, and the furnace cavity of the flue gas exhaust zone increase in size by a factor of two in succession.

[0016] In some embodiments of the present invention, the kiln body has a kiln roof and a kiln bottom. The kiln roof includes a first refractory layer, and the kiln bottom includes a second refractory layer. The thickness of the kiln roof in the high-temperature firing zone, the kiln roof in the medium-temperature firing zone, the kiln roof in the preheating zone, and the kiln roof in the flue gas zone increases sequentially in multiples of the number of the first refractory layers. The thickness of the kiln bottom in the high-temperature firing zone, the kiln bottom in the medium-temperature firing zone, the kiln bottom in the preheating zone, and the kiln bottom in the flue gas zone increases sequentially in multiples of the number of the second refractory layers.

[0017] In some embodiments of the present invention, the cross-sectional area of ​​the intermediate firing zone is 1.18 to 1.21 times or greater than the cross-sectional area of ​​the high firing zone, the cross-sectional area of ​​the preheating zone is 1.46 to 1.52 times or greater than the cross-sectional area of ​​the high firing zone, and the cross-sectional area of ​​the exhaust zone is 1.87 to 1.94 times or greater than the cross-sectional area of ​​the high firing zone.

[0018] In some embodiments of the present invention, the smoke exhaust zone, the preheating zone, the intermediate firing zone, and the high firing zone are equal in outer width.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0021] Figure 1 This is a simplified diagram of the internal structure of the stepped kiln with automatic control of combustion flue gas velocity provided in the embodiments of the present invention, viewed from a top-down angle.

[0022] Figure 2 This is a simplified internal structure diagram of the stepped kiln with automatic control of combustion flue gas velocity provided in the embodiments of the present invention, viewed from a side angle.

[0023] Figure 3 This is a schematic diagram of the internal structure of the exhaust zone in the stepped kiln with automatic control of combustion flue gas velocity provided in the embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the internal structure of the preheating zone in the stepped kiln with automatic control of combustion flue gas velocity provided in the embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the internal structure of the firing medium-temperature zone in the stepped kiln with automatic control of combustion flue gas flow rate provided in the embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the internal structure of the high-temperature firing zone in a stepped kiln with automatically controlled combustion flue gas velocity provided in an embodiment of the present invention.

[0027] The following markings are shown in the attached diagram: 110, smoke exhaust zone; 120, preheating zone; 130, medium-temperature firing zone; 140, high-temperature firing zone; 210, furnace cavity; 220, kiln roof refractory insulation layer; 230, kiln bottom refractory insulation layer; 240, side wall refractory insulation layer; 250, roller holes. Detailed Implementation

[0028] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0029] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0030] In the description of this invention, the use of terms such as "a number" means one or more, with "more than" meaning two or more. Terms like "greater than," "less than," and "exceeding" are understood to exclude the stated number, while terms like "above," "below," and "within" are understood to include the stated number. The use of terms like "first," "second," and "third" is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, the number of indicated technical features, or the sequential relationship between indicated technical features.

[0031] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0032] Reference Figures 1 to 6 The following are several embodiments of the stepped kiln with automatic control of combustion flue gas velocity according to the present invention.

[0033] Ceramics are sintered in the high-temperature environment of a kiln. With continuous improvements and upgrades in ceramic processing formulas and kiln structure technology, the firing cycle (the time from when the ceramic body enters the kiln to when it exits) is becoming shorter, and the output per production line is increasing. To ensure output, regardless of the kiln's length, the firing cycle for the same type of ceramic is relatively fixed. Taking ceramic tiles as an example, the shortest firing cycle for polished tiles is currently 14 minutes. Whether using a 50m long kiln or a 500m long kiln, the firing time for polished tiles is 14 minutes. Therefore, with kilns of the same length and internal width, the output of ceramics increases exponentially due to the shortened firing cycle.

[0034] Under normal kiln operation, exhaust fans are needed to balance the pressure inside the kiln; that is, the amount of combustion gas produced must be matched by the amount of combustion gas discharged. When ceramic production increases, ceramic manufacturers typically use exhaust fans with high pressure and large flow rates. However, this can lead to very high negative pressure in the exhaust and preheating zones, and extremely high positive pressure in the firing zone. This results in the following problems: large temperature differences across the kiln cross-sections, decreased quality of finished ceramic products, severe air and fire leakage, increased energy consumption, and higher ceramic production costs.

[0035] Based on the above-mentioned technical problems, the present invention provides a stepped kiln with automatic control of combustion flue gas velocity, which can automatically reduce the velocity of combustion flue gas, which is beneficial to reducing the power performance requirements of the exhaust fan, saving energy, and solving the serious technical problems in the prior art such as excessive negative pressure in the exhaust zone and preheating zone, excessive positive pressure in the firing zone, and the resulting large cross-sectional temperature difference, increased energy consumption, easy cracking of the green body, and low heat utilization rate.

[0036] like Figures 1 to 6 As shown, the cascade kiln with automatic control of combustion flue gas velocity provided in this embodiment has a first direction, a second direction, and a third direction, wherein the first direction, the second direction, and the third direction are perpendicular to each other. In this embodiment, it is assumed that the first direction is the front-to-back direction, the second direction is the left-to-right direction, and the third direction is the up-down direction.

[0037] The structure of a stepped kiln with automatically controlled combustion flue gas velocity includes a kiln body extending along a first direction. The kiln body is hollow, forming a furnace cavity 210. The furnace cavity 210 extends along the first direction and penetrates opposite sides of the kiln body along the first direction, allowing ceramic blanks to enter and exit the furnace cavity 210 along the first direction. The kiln body is a roller kiln. The kiln body has a kiln roof, a kiln bottom, and kiln walls. Kiln walls are located on opposite sides of the kiln roof, and the kiln roof, kiln bottom, and side kiln walls together form the furnace cavity 210.

[0038] The kiln body structure includes a flue gas exhaust zone 110, a preheating zone 120, a firing zone, and a cooling zone. The flue gas exhaust zone 110, preheating zone 120, firing zone, and cooling zone are arranged sequentially along a first direction and are interconnected. It is understood that each of the flue gas exhaust zone 110, preheating zone 120, firing zone, and cooling zone has a corresponding furnace cavity 210. The kiln head is located at the end of the flue gas exhaust zone 110 furthest from the preheating zone 120, and the kiln tail is located at the end of the cooling zone furthest from the firing zone.

[0039] The cross-sectional areas of the furnace cavity 210 in the firing zone, the furnace cavity 210 in the preheating zone 120, and the furnace cavity 210 in the flue gas exhaust zone 110 increase sequentially. Specifically, the cross-sectional area of ​​the furnace cavity 210 in the flue gas exhaust zone 110 is larger than that in the preheating zone 120, and the cross-sectional area of ​​the furnace cavity 210 in the preheating zone 120 is larger than that in the firing zone 210.

[0040] Understandably, the ceramic blank enters from the kiln head and passes through the flue gas zone 110, the preheating zone 120, and the firing zone in sequence. During this process, the temperature of the ceramic blank increases from low to high. After the ceramic blank reaches the highest temperature zone and completes sintering and vitrification, it will continue to move along the first direction and enter the cooling zone to complete the cooling process, so that the finished ceramic product can achieve the required function after it comes out of the kiln tail.

[0041] To achieve cooling and energy conservation, the combustion flue gas within the furnace cavity 210 flows from the firing zone to the exhaust zone 110 under the suction of the exhaust fan, and is extracted at the kiln head. Furthermore, as the combustion flue gas flows from the firing zone to the preheating zone 120 and the exhaust zone 110, it continuously transfers heat to the ceramic blanks, causing the blanks' temperature to gradually rise while the flue gas's temperature continuously decreases. The combustion flue gas is then exhausted outside the kiln under suction and undergoes centralized desulfurization, denitrification, and dust removal treatment before being released into the atmosphere after meeting emission standards. Inside the kiln, the flow direction of the combustion flue gas is opposite to the direction of the blanks' movement.

[0042] Because the firing zone is equipped with burners, it generates a certain amount of combustion flue gas. The preheating zone 120 is also equipped with burners, generating a similar amount of combustion flue gas. Therefore, the amount of combustion flue gas extracted from the kiln head gradually increases from the firing zone to the preheating zone 120. This means the combustion flue gas is least abundant in the firing zone and continuously mixes with combustion products from other areas (preheating zone 120) as it flows towards the kiln head, causing the amount of combustion flue gas to continuously increase until it reaches its maximum at the kiln head. When the cross-sectional areas of the exhaust zone 110, preheating zone 120, and firing zone are essentially the same, the cumulative flue gas volume in the preheating zone 120 results in a higher flue gas velocity than in the firing zone, leading to a pressure imbalance within the kiln.

[0043] Based on this, the stepped kiln with automatic control of combustion flue gas velocity in this embodiment breaks away from the influence of traditional thinking. According to the kiln body structure, the gradual accumulation of flue gas volume along the length of the kiln body, and the combustion characteristics, the cross-sectional area of ​​the corresponding furnace cavity 210 in each region of the kiln body is changed. The cross-sectional area of ​​the firing zone, the preheating zone 120, and the exhaust zone 110 gradually increases in sequence, so that the furnace cavity 210 of the kiln body increases in a stepped manner from the firing zone to the exhaust zone 110. This automatically reduces the flue gas velocity in the kiln body, resulting in a small positive pressure in the firing zone and a small negative pressure in the preheating zone 120 and the exhaust zone 110. This achieves the goal of automatically controlling the flow rate of combustion flue gas to be smaller, reducing the power of the exhaust fan, resulting in a small cross-sectional temperature difference in the furnace cavity 210, good heat exchange effect, saving electricity and fuel, and making the green body less prone to cracking.

[0044] In this embodiment, the firing zone structure includes a medium-temperature firing zone 130 and a high-temperature firing zone 140. The preheating zone 120, the medium-temperature firing zone 130, and the high-temperature firing zone 140 are sequentially arranged along a first direction and are interconnected. The furnace cavity 210 of the high-temperature firing zone 140, the furnace cavity 210 of the medium-temperature firing zone 130, and the furnace cavity 210 of the preheating zone 120 increase in cross-sectional area sequentially.

[0045] Since burners are installed in the intermediate firing zone 130 and the high firing zone 140 respectively, each producing a certain amount of combustion flue gas, the amount of combustion flue gas in the intermediate firing zone 130 is greater than that in the high firing zone 140. By designing the cross-sectional area of ​​the furnace cavity 210 in the intermediate firing zone 130 to be larger than that in the high firing zone 140 but smaller than that in the preheating zone 120, the flue gas velocity within the kiln body decreases. This significantly reduces the positive pressure in both the high firing zone 140 and the intermediate firing zone 130, thus preventing problems such as severe flame leakage leading to increased fuel consumption by the burners, large flame jet resistance leading to large cross-sectional temperature differences, and excessive heat dissipation from the side walls leading to increased energy consumption. This achieves low heat dissipation. The purpose is to save energy; on the other hand, it significantly reduces the negative pressure in the preheating zone 120 and the exhaust zone 110. With low negative pressure in the preheating zone 120 and the exhaust zone 110, the burner flame can be directly sprayed into the middle of the kiln, reducing the cross-sectional temperature difference of the furnace cavity 210 and improving the firing quality of the ceramic products. At the same time, it can reduce the air leakage of the roller holes 250, observation holes and other holes, save fuel, and avoid the problems of ceramic blanks being prone to cracking due to high kiln head temperature and increased energy consumption due to high exhaust temperature. Moreover, it reduces the flue gas velocity, prolongs the heat exchange time between the flue gas and the ceramic blank, and improves the heat utilization rate.

[0046] In this embodiment, as Figures 1 to 6As shown, the furnace cavity 210 of the high-temperature firing zone 140, the furnace cavity 210 of the medium-temperature firing zone 130, the furnace cavity 210 of the preheating zone 120, and the furnace cavity 210 of the exhaust zone 110 increase in inner width sequentially. Moreover, the furnace cavity 210 of the high-temperature firing zone 140, the furnace cavity 210 of the medium-temperature firing zone 130, the furnace cavity 210 of the preheating zone 120, and the furnace cavity 210 of the exhaust zone 110 increase in inner height sequentially.

[0047] It is understandable that the furnace cavity 210 of the kiln body has an inner width and an inner height. The inner width is the distance between the two kiln walls on opposite sides, and the inner height is the distance between the kiln top and the kiln bottom. The cross-sectional area of ​​the furnace cavity 210 is equal to the product of the inner width and the inner height.

[0048] The inner width of the high-temperature firing zone 140 is set as x0, and the inner height as y0; the inner width of the medium-temperature firing zone 130 is set as x1, and the inner height as y1; the inner width of the preheating zone 120 is set as x2, and the inner height as y2; the inner width of the exhaust zone 110 is set as x3, and the inner height as y3. Wherein, x3 > x2 > x1 > x0, and y3 > y2 > y1 > y0.

[0049] Based on the different temperatures in each area of ​​the kiln body, the inner height and inner width of the high-temperature firing zone 140, the medium-temperature firing zone 130, the preheating zone 120, and the smoke exhaust zone 110 are gradually increased, thereby forming multiple stepped furnace cavities 210.

[0050] In some examples, the furnace cavity 210 of the high-temperature firing zone 140, the furnace cavity 210 of the medium-temperature firing zone 130, the furnace cavity 210 of the preheating zone 120, and the furnace cavity 210 of the flue gas exhaust zone 110 increase in internal width sequentially in an arithmetic progression. Of course, it is not impossible that the furnace cavity 210 of the high-temperature firing zone 140, the furnace cavity 210 of the medium-temperature firing zone 130, the furnace cavity 210 of the preheating zone 120, and the furnace cavity 210 of the flue gas exhaust zone 110 increase in internal width sequentially in a non-arithmetic progression.

[0051] In a specific example, the kiln walls on opposite sides of the high-temperature firing zone 140 have equal thickness, the kiln walls on opposite sides of the medium-temperature firing zone 130 have equal thickness, the kiln walls on opposite sides of the preheating zone 120 have equal thickness, and the kiln walls on opposite sides of the exhaust zone 110 have equal thickness. It is understood that when the inner width of the furnace cavity 210 changes in the high-temperature firing zone 140, the medium-temperature firing zone 130, the preheating zone 120, and the exhaust zone 110, the thickness of the kiln walls on opposite sides changes simultaneously. This avoids the problem of excessive heat dissipation, poor heat preservation, and increased manufacturing costs of the kiln body due to one side's kiln wall being too thick and the other side's being too thin.

[0052] Of course, there are some differences in the thickness of the kiln walls on both sides of the high-temperature firing zone 140, the medium-temperature firing zone 130, the preheating zone 120, and the smoke exhaust zone 110. The walls at higher temperatures are thicker, while the walls at lower temperatures are thinner.

[0053] In some examples, the furnace cavity 210 of the high-temperature firing zone 140, the furnace cavity 210 of the medium-temperature firing zone 130, the furnace cavity 210 of the preheating zone 120, and the furnace cavity 210 of the flue gas exhaust zone 110 increase in internal height in a sequentially multiple manner. Of course, it is not excluded that the furnace cavity 210 of the high-temperature firing zone 140, the furnace cavity 210 of the medium-temperature firing zone 130, the furnace cavity 210 of the preheating zone 120, and the furnace cavity 210 of the flue gas exhaust zone 110 increase in internal height in a non-multiple manner.

[0054] In a specific example, the kiln roof thickness of the high-temperature firing zone 140, the kiln roof thickness of the medium-temperature firing zone 130, the kiln roof thickness of the preheating zone 120, and the kiln roof thickness of the flue gas zone 110 increase sequentially. In addition, the kiln bottom thickness of the high-temperature firing zone 140, the kiln bottom thickness of the medium-temperature firing zone 130, the kiln bottom thickness of the preheating zone 120, and the kiln bottom thickness of the flue gas zone 110 increase sequentially.

[0055] The kiln top includes the first refractory layer, and the kiln bottom includes the second refractory layer.

[0056] The kiln roof thickness of the high-temperature firing zone 140, the kiln roof thickness of the medium-temperature firing zone 130, the kiln roof thickness of the preheating zone 120, and the kiln roof thickness of the flue gas zone 110 increase in multiples according to the number of first refractory layers.

[0057] The kiln bottom thicknesses of the high-temperature firing zone 140, the medium-temperature firing zone 130, the preheating zone 120, and the flue gas zone 110 increase in multiples according to the number of second refractory layers.

[0058] It is understandable that the kiln body has sidewall refractory insulation layers 240 on opposite sides, a kiln roof refractory insulation layer 220 on the top, and a kiln bottom refractory insulation layer 230 on the bottom. The kiln roof refractory insulation layer 220 is the first refractory layer, and the kiln bottom refractory insulation layer 230 is the second refractory layer. The structure of the sidewall refractory insulation layer 240 includes insulation cotton board, and both the kiln roof refractory insulation layer 220 and the kiln bottom refractory insulation layer 230 include refractory insulating bricks; that is, both the first and second refractory layers are made of refractory insulating bricks. Generally, the insulation cotton board is 50mm thick, the refractory insulating bricks are 64mm to 65mm thick, and the mortar joints between the refractory insulating bricks are 1mm to 2mm thick.

[0059] Therefore, taking the inner width and inner height of the high-temperature firing zone 140 as a benchmark, and setting the inner width of the high-temperature firing zone 140 as x0 and the inner height as y0, with units of meters (m), the sidewall thickness of the intermediate-temperature firing zone 130, preheating zone 120, and exhaust zone 110 can be reduced by 50 mm, and the thickness of the kiln top and bottom of the intermediate-temperature firing zone 130, preheating zone 120, and exhaust zone 110 can be reduced by multiples of 66 mm. Then, the inner width of the intermediate-temperature firing zone 130 is x1 = x0 + 0.1, and the inner height is y1 = y0 + 0.132; the inner width of the preheating zone 120 is x2 = x0 + 0.2, and the inner height is y2 = y0 + 0.33; and the inner width of the exhaust zone 110 is x3 = x0 + 0.3, and the inner height is y3 = y0 + 0.396.

[0060] It is understandable that the cross-sectional area of ​​the furnace cavity 210 is the product of its inner width and inner height. After obtaining the inner width and inner height dimensions of the high-temperature firing zone 140, the medium-temperature firing zone 130, the preheating zone 120, and the smoke exhaust zone 110, the corresponding cross-sectional area can be calculated.

[0061] Taking a common flat-top roller kiln with an inner width of 2m and 3m as an example, the dimensions of each area of ​​the kiln body are designed according to the aforementioned variations in inner width and inner height (since the invention of this embodiment does not involve the cooling zone, the cooling zone is ignored), as detailed in Tables 1 and 2 below. It can be understood that in existing kiln structures, the inner height of the exhaust zone 110 is less than the inner height of the preheating zone 120, and the inner width of the exhaust zone 110 is slightly greater than the inner width of the preheating zone 120. The inner width and inner height of the preheating zone 120, the medium-temperature firing zone 130, and the high-temperature firing zone 140 are the same.

[0062] Table 1 is as follows:

[0063]

[0064] Table 2 details are as follows:

[0065]

[0066] From the above, we can conclude that in Example 1, taking the high-temperature firing zone 140 as a reference, the thickness of the kiln walls on both sides of the intermediate-temperature firing zone 130 is reduced by 50mm, which means one insulation board is removed from each side, resulting in a total reduction of 100mm in the thickness of the kiln walls on both sides. The total thickness of the kiln top and bottom of the intermediate-temperature firing zone 130 is reduced by 132mm, which means two refractory insulation bricks are removed from each side, making the cross-sectional area of ​​the intermediate-temperature firing zone 130 120.75% of the cross-sectional area of ​​the high-temperature firing zone 140. The thickness of the kiln walls on both sides of the preheating zone 120 is reduced by 100mm, which means two insulation boards are removed from each side, resulting in a total reduction of 200mm in the thickness of the kiln walls on both sides. The total thickness of the kiln top and bottom of the preheating zone 120 is reduced by 330mm, which means five refractory insulation bricks are removed from each side, making the cross-sectional area of ​​the preheating zone 120 151.25% of the cross-sectional area of ​​the high-temperature firing zone 140. The thickness of the kiln walls on both sides of the flue gas zone 110 is reduced by 150mm, which means three insulation boards are reduced on each side, resulting in a total reduction of 300mm in the thickness of the kiln walls on both sides. The total thickness of the kiln top and bottom of the flue gas zone 110 is reduced by 396mm, which means a total reduction of six refractory insulation bricks, making the cross-sectional area of ​​the flue gas zone 110 193.83% of the cross-sectional area of ​​the high-temperature firing zone 140.

[0067] In Example 2, also using the high-temperature firing zone 140 as a reference, the thickness of the kiln walls on both sides of the intermediate-temperature firing zone 130 is reduced by 50 mm each, resulting in a total reduction of 100 mm in the thickness of the kiln walls on both sides. The total thickness of the kiln top and bottom of the intermediate-temperature firing zone 130 is reduced by 132 mm, making the cross-sectional area of ​​the intermediate-temperature firing zone 130 118.83% of the cross-sectional area of ​​the high-temperature firing zone 140. Similarly, the thickness of the kiln walls on both sides of the preheating zone 120 is reduced by 100 mm each, resulting in a total reduction of 200 mm in the thickness of the kiln walls on both sides. The total thickness of the kiln top and bottom of the preheating zone 120 is reduced by 330 mm, making the cross-sectional area of ​​the preheating zone 120 146.67% of the cross-sectional area of ​​the high-temperature firing zone 140. The kiln walls on both sides of the flue gas zone 110 are reduced by 150mm respectively, resulting in a total reduction of 300mm in the thickness of the kiln walls on both sides. The total thickness of the kiln top and bottom of the flue gas zone 110 is reduced by 396mm, making the cross-sectional area of ​​the flue gas zone 110 187.22% of the cross-sectional area of ​​the high-temperature firing zone 140.

[0068] Therefore, the inner width dimensions of the firing intermediate temperature zone 130, preheating zone 120, and smoke exhaust zone 110 all increase sequentially in an arithmetic progression, with a tolerance of 100mm. The inner height dimensions of the firing intermediate temperature zone 130, preheating zone 120, and smoke exhaust zone 110 all increase sequentially in multiples. Specifically, the inner height dimension of the firing intermediate temperature zone 130 increases by the total thickness of two refractory insulating bricks, the inner height dimension of the preheating zone 120 increases by the total thickness of five refractory insulating bricks, and the inner height dimension of the smoke exhaust zone 110 increases by the total thickness of six refractory insulating bricks. In other words, the smoke exhaust zone 110, preheating zone 120, and firing intermediate temperature zone 130 increase in multiples according to the number of refractory insulating bricks.

[0069] By reducing the number of refractory insulating bricks on the kiln roof in the vertical direction, the thickness of the kiln roof in the high-temperature firing zone 140, the medium-temperature firing zone 130, the preheating zone 120, and the flue gas exhaust zone 110 is increased sequentially by multiples, while ensuring that the temperature of each area of ​​the kiln body meets the working requirements.

[0070] By reducing the number of refractory insulating bricks at the bottom of the kiln in the vertical direction, the thickness of the kiln bottom in the high-temperature firing zone 140, the medium-temperature firing zone 130, the preheating zone 120, and the flue gas zone 110 is increased sequentially by multiples, while ensuring that the temperature of each area of ​​the kiln body meets the working requirements.

[0071] By reducing the number of refractory insulation cotton boards installed in the left and right directions of the kiln walls, the thickness of the kiln walls on both sides of the high-temperature firing zone 140, the medium-temperature firing zone 130, the preheating zone 120, and the exhaust zone 110 is increased sequentially in an arithmetic progression.

[0072] This design makes it easy to manufacture the various areas of the kiln body and adjust their internal width and height dimensions.

[0073] It is understandable that when the total thickness of the kiln top and bottom is reduced by the sum of the thicknesses of an even number of refractory and insulating bricks, the same number of refractory and insulating bricks can be reduced for both the kiln top and bottom. When the total thickness of the kiln top and bottom is reduced by the sum of the thicknesses of an odd number of refractory and insulating bricks, the number of refractory and insulating bricks reduced for the kiln top can be greater than the number of refractory and insulating bricks reduced for the kiln bottom.

[0074] Without changing the existing dimensions (inner width and inner height) of the high-temperature firing zone 140, the cross-sectional area of ​​the intermediate-temperature firing zone 130 can be set to 1.18 to 1.21 times the cross-sectional area of ​​the high-temperature firing zone 140, the cross-sectional area of ​​the preheating zone 120 can be set to 1.46 to 1.52 times the cross-sectional area of ​​the high-temperature firing zone 140, and the cross-sectional area of ​​the smoke exhaust zone 110 can be set to 1.87 to 1.94 times the cross-sectional area of ​​the high-temperature firing zone 140. Preferably, relative to the high-temperature firing zone 140, the cross-sectional areas of the medium-temperature firing zone 130, the preheating zone 120, and the exhaust zone 110 are increased by 0.2 times, 0.5 times, and 1 time, respectively. Under the same conditions of output, temperature, and kiln pressure, the kiln flue gas velocity in the exhaust zone 110 can be reduced by 50%, and the power of the exhaust fan can be reduced by 50%, saving a lot of electricity. Moreover, the heat exchange time between the flue gas and the green body is increased, making the heat transfer more complete, which is conducive to improving the firing quality of the ceramic products. In addition, the temperature of the flue gas flowing to the kiln head decreases, making the ceramic green body less prone to cracking, thereby reducing the scrap rate.

[0075] Moreover, with appropriate material selection and scientific configuration, theoretical calculations and actual tests show that after the corresponding refractory insulation layer of the kiln body is thinned according to the above dimensions, the surface temperature of the kiln body is comparable to that of kilns in the prior art.

[0076] Furthermore, in other embodiments, the cross-sectional area of ​​the intermediate firing zone 130 is 1.21 times larger than that of the high firing zone 140, the cross-sectional area of ​​the preheating zone 120 is 1.52 times larger than that of the high firing zone 140, and the cross-sectional area of ​​the exhaust zone 110 is 1.94 times larger than that of the high firing zone 140.

[0077] Of course, it is possible to increase the inner width of the furnace cavity 210 in the high-temperature zone 140, the furnace cavity 210 in the medium-temperature zone 130, the furnace cavity 210 in the preheating zone 120, and the furnace cavity 210 in the smoke exhaust zone 110 sequentially, while keeping the inner height unchanged; or, to increase the inner height of the furnace cavity 210 in the high-temperature zone 140, the furnace cavity 210 in the medium-temperature zone 130, the furnace cavity 210 in the preheating zone 120, and the furnace cavity 210 in the smoke exhaust zone 110 sequentially, while keeping the inner width unchanged.

[0078] In this embodiment, the smoke exhaust zone 110, the preheating zone 120, the medium-temperature firing zone 130, and the high-temperature firing zone 140 are equal in outer width.

[0079] It is understandable that in existing kilns, the exhaust zone 110 is narrower than the preheating zone 120, meaning that the outer width of the exhaust zone 110 is smaller than that of the preheating zone 120. This results in the frame columns at the junction between the exhaust zone 110 and the preheating zone 120 being misaligned. Therefore, after the kiln is heated, the temperature of the metal frame will also increase by tens of degrees or even higher, causing the kiln body to expand and undergo a certain displacement. This can easily cause the frame of the exhaust zone 110 to be squeezed and deformed.

[0080] So, if Figures 3 to 6 As shown, in this embodiment, by setting the outer width dimensions of the smoke exhaust zone 110, the preheating zone 120, the firing medium-temperature zone 130, and the firing high-temperature zone 140 to be equal, that is, their outer width dimensions are all L, where the value of L can be set according to the actual situation, that is, changed to the same width of the kiln body, so that the frame columns of the smoke exhaust zone 110, the preheating zone 120, the firing medium-temperature zone 130, and the firing high-temperature zone 140 are on the same straight line, the above-mentioned frame deformation problem can be avoided.

[0081] Although the increased outer width of the exhaust zone 110 slightly increases the length of the rollers, frame steel, and refractory materials, the thinning of the refractory insulation layer in the intermediate firing zone 130 and the preheating zone 120, along with the shortening of the hooks, saves costs; overall, the cost still decreases. If the power of the exhaust fan is reduced, the cost of the cascade kiln with automatic control of the combustion flue gas velocity in this embodiment will further decrease.

[0082] In addition, the smoke exhaust zone 110, preheating zone 120, medium-temperature firing zone 130 and high-temperature firing zone 140 have the same outer width and height, and the same shape will be more harmonious and beautiful.

[0083] In this embodiment, the outer height and width dimensions of the frame of each region of the kiln body are consistent, making the outer surface of the refractory insulation layer flush. Then, according to the different operating temperatures of each region of the kiln body, the refractory insulation layer is thinned sequentially in the firing medium temperature zone 130, the preheating zone 120, and the smoke exhaust zone 110. This is equivalent to the inner height and inner width dimensions of the firing high temperature zone 140, the firing medium temperature zone 130, the preheating zone 120, and the smoke exhaust zone 110 being gradually increased sequentially, forming multiple stepped furnace cavities 210. This increases the cross-sectional area of ​​the internal channels of the firing medium temperature zone 130, the preheating zone 120, and the smoke exhaust zone 110 (that is, the cross-sectional area of ​​the furnace cavity 210 is increased).

[0084] The length of the flue gas exhaust zone 110 accounts for 8% to 12% of the total kiln length, the length of the preheating zone 120 accounts for 10% to 15% of the total kiln length, the length of the medium-temperature firing zone 130 accounts for 10% to 15% of the total kiln length, and the length of the high-temperature firing zone 140 accounts for 18% to 25% of the total kiln length.

[0085] The stepped kiln with automatic control of combustion flue gas flow rate in this embodiment can greatly reduce flue gas resistance. If it is necessary to slow down the flow of flue gas, it can be achieved by setting and adjusting the baffle plate (top), the fire wall (bottom of the kiln), or the suction force of the exhaust fan.

[0086] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A stepped kiln with automatic control of combustion flue gas velocity, characterized in that, The furnace includes a kiln body, which has a furnace cavity extending along a first direction in its length direction. The kiln body includes a smoke exhaust zone, a preheating zone, and a firing zone that are arranged sequentially and connected along the first direction. The furnace cavity of the firing zone, the furnace cavity of the preheating zone, and the furnace cavity of the smoke exhaust zone increase in cross-sectional area sequentially. The firing zone includes a medium-temperature firing zone and a high-temperature firing zone, and the preheating zone, the medium-temperature firing zone, and the high-temperature firing zone are arranged sequentially and connected along a first direction; Furthermore, the cross-sectional area of ​​the furnace cavity in the high-temperature firing zone, the furnace cavity in the medium-temperature firing zone, and the furnace cavity in the preheating zone increases sequentially. The kiln body has a kiln roof and a kiln bottom. The kiln roof includes a first refractory layer, and the kiln bottom includes a second refractory layer. The thickness of the kiln roof in the high-temperature firing zone, the kiln roof in the medium-temperature firing zone, the kiln roof in the preheating zone, and the kiln roof in the flue gas zone increases sequentially in multiples of the number of first refractory layers. The thickness of the kiln bottom in the high-temperature firing zone, the kiln bottom in the medium-temperature firing zone, the kiln bottom in the preheating zone, and the kiln bottom in the flue gas zone increases sequentially in multiples of the number of second refractory layers. The cross-sectional area of ​​the intermediate firing zone is 1.18 to 1.21 times that of the high firing zone, the cross-sectional area of ​​the preheating zone is 1.46 to 1.52 times that of the high firing zone, and the cross-sectional area of ​​the exhaust zone is 1.87 to 1.94 times that of the high firing zone.

2. The stepped kiln with automatic control of combustion flue gas velocity according to claim 1, characterized in that, The furnace cavity of the high-temperature firing zone, the furnace cavity of the medium-temperature firing zone, the furnace cavity of the preheating zone, and the furnace cavity of the flue gas exhaust zone increase in size sequentially.

3. The stepped kiln with automatic control of combustion flue gas velocity according to claim 2, characterized in that, The furnace cavities of the high-temperature firing zone, the medium-temperature firing zone, the preheating zone, and the exhaust zone increase in width sequentially according to an arithmetic progression.

4. The stepped kiln with automatic control of combustion flue gas velocity according to claim 3, characterized in that, The kiln walls on opposite sides of the high-temperature firing zone have equal thickness, the kiln walls on opposite sides of the medium-temperature firing zone have equal thickness, the kiln walls on opposite sides of the preheating zone have equal thickness, and the kiln walls on opposite sides of the flue gas zone have equal thickness.

5. The stepped kiln with automatic control of combustion flue gas velocity according to any one of claims 1 to 4, characterized in that, The furnace cavity of the high-temperature firing zone, the furnace cavity of the medium-temperature firing zone, the furnace cavity of the preheating zone, and the furnace cavity of the flue gas exhaust zone increase in height sequentially.

6. The stepped kiln with automatic control of combustion flue gas velocity according to claim 5, characterized in that, The furnace cavity of the high-temperature firing zone, the furnace cavity of the medium-temperature firing zone, the furnace cavity of the preheating zone, and the furnace cavity of the flue gas exhaust zone increase in size by a factor of two in successive multiples.

7. The stepped kiln with automatic control of combustion flue gas velocity according to claim 1, characterized in that, The smoke exhaust zone, the preheating zone, the intermediate firing zone, and the high firing zone are equal in outer width.

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