Composite lining structure for a rotary kiln

Abstract

The utility model discloses a composite lining structure of rotary kiln, and the rotary kiln has a cylinder, and the cylinder includes preheating zone cylinder, firing zone cylinder and cooling zone cylinder which are connected in sequence, the first pouring layer is built in the firing zone cylinder, and the refractory brick layer is built in the first pouring layer, the refractory felt is also laid between the firing zone cylinder and the first pouring layer, and the silicium calcium board is also laid between the refractory felt and the first pouring layer, the utility model has the beneficial effect that through the double setting of the first pouring layer and the refractory brick layer, the lining thickness is increased, the cylinder weight is reduced, and the working demand is satisfied.

Description

Technical Field

[0001] This utility model relates to the field of refractory material production and processing technology, and in particular to the composite lining structure of rotary kilns. Background Technology

[0002] Rotary kilns are a type of dynamic, continuous production kiln. Due to their high output, low cost, uniform and stable product firing quality, and environmental friendliness, they are very suitable for producing various high-temperature refractory raw materials.

[0003] For a long time, the refractory lining of rotary kilns has been constructed using a single type of refractory brick, with a lining thickness typically ≤230mm. Due to the high thermal conductivity of refractory bricks and the excessively thin lining, the heat dissipation temperature on the outer surface of the rotary kiln shell is excessively high, reaching as high as 360 degrees Celsius in the firing zone. The prolonged exposure of the rotary kiln's outer surface to this high-temperature environment has the following drawbacks: 1. This results in persistently high energy consumption per unit of product and enormous waste of resources; 2. The surface temperature of the outer cylinder in the firing zone reaches as high as 360 degrees Celsius, which reduces the strength of the steel cylinder and poses certain safety risks to the operation of the large kiln. 3. Due to environmental protection requirements, rotary kilns are generally built indoors, where the indoor temperature is high, especially in summer, and the kiln operators are often drenched in sweat, resulting in poor working conditions. 4. Due to the waste of energy, the firing cost of the products increased, reducing the company's profits; 5. Due to the waste of energy, the amount of pollutants emitted in the exhaust gas increases accordingly, which is detrimental to environmental protection.

[0004] In September 2020, the government introduced a dual-carbon policy. Under the dual pressure of national environmental protection policies and market competition, many manufacturers in the industry have made many beneficial explorations and attempts. Among them, two methods have been relatively successful: 1. As per the instruction manual Figure 1 As shown, the refractory brick lining is thickened, and a double-layer lining is constructed: first, a layer of lightweight insulating bricks 12 with a thickness of 80-150mm and a density of approximately 2.2Kg / m3 is laid on the cylinder 10; then, a layer of refractory bricks 13 with a thickness of 180-230mm is laid on top of the insulating bricks 12 for the working layer. The total lining thickness is increased to approximately 350mm, and the added insulation layer reduces the heat dissipation temperature of the outer cylinder in the firing zone to approximately 280 degrees Celsius, reducing the heat dissipation temperature by about 80 degrees Celsius, thus achieving a certain energy-saving effect.

[0005] However, since a rotary kiln is a dynamic rotating device with a certain load, not only is it required that the total weight of the lining cannot exceed a certain load, but the lining is also subjected to high shear and extrusion forces when rotating at high temperatures in the rotary kiln. Due to strength requirements, the density of lightweight insulating bricks cannot be lower than 2.0 kg / m3. Therefore, the energy-saving effect of this method is limited and there is no potential to be explored.

[0006] 2. As per the instruction manual Figure 2 As shown, the lining is constructed using a strip-combination method similar to that used in cement rotary kilns: the rotary kiln cylinder 10 is divided into several equal-width strips along its axial direction, typically the width of refractory bricks 22. Refractory bricks 22 and castable refractory 21 are then interleaved and combined, meaning adjacent lining strips consist of one strip of refractory bricks 22 and the other of castable refractory 21, with anchors 23 embedded within the castable refractory 21. This construction method can reduce the heat dissipation temperature of the outer cylinder surface corresponding to the castable refractory lining, and also has a certain energy-saving effect.

[0007] However, since the firing temperature of cement rotary kilns is relatively low (generally 1450 degrees Celsius), while the firing temperature of refractory rotary kilns is relatively high (generally 1650-1750 degrees Celsius), the 2520 alloy anchors embedded in the castable cannot withstand the high temperature of the refractory materials. Therefore, this method cannot be used for the firing zone of refractory rotary kilns, and the energy saving is limited. Thus, this method cannot be promoted for the lining of refractory rotary kilns.

[0008] For example, patent application number "CN202021166253.3" discloses "an energy-saving lining structure for a rotary kiln." Although it can reduce heat loss inside the kiln and lower the external temperature of the kiln to some extent, this structure is inconsistent with the appendix to the specification. Figure 2 Similarly, this is achieved by alternating precast bricks and castable refractory materials, but it also has its shortcomings. Summary of the Invention

[0009] The purpose of this invention is to provide a composite lining structure for rotary kilns, which reduces the weight of the rotary kilns while meeting their heat insulation requirements.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: The rotary kiln has a composite lining structure, and the rotary kiln has a cylinder, which includes a preheating zone cylinder, a firing zone cylinder and a cooling zone cylinder connected in sequence. The firing zone cylinder is lined with a first casting layer, and the first casting layer is lined with a refractory brick layer.

[0011] Preferably, a refractory felt is also laid between the firing belt cylinder and the first casting layer.

[0012] Preferably, a calcium silicate board is also laid between the refractory felt and the first casting layer.

[0013] Preferably, the firing belt cylinder is further provided with anchors.

[0014] Preferably, the thickness of the first casting layer is not less than 270 mm.

[0015] Preferably, the thickness of the refractory brick layer is not less than 230 mm.

[0016] Preferably, the preheating zone cylinder and the cooling zone cylinder have the same structure, and a second casting layer and a third casting layer are sequentially built inside the preheating zone cylinder and the cooling zone cylinder.

[0017] The beneficial effects of this utility model are as follows: 1. By using a dual design of the first casting layer and the refractory brick layer, the lining thickness is increased and the weight of the cylinder is reduced, thus meeting the operational requirements.

[0018] 2. Refractory felt and calcium silicate board are also laid between the firing zone cylinder and the first casting layer. These materials are not only lightweight, but also have extremely low thermal conductivity, which can greatly reduce heat loss.

[0019] 3. Two composite casting layers are sequentially built inside the preheating zone cylinder and the cooling zone cylinder, which can greatly reduce the loss of high temperature and lower the temperature on the outside of the cylinder. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a rotary kiln shell in the prior art; Figure 2 This is a schematic diagram of another rotary kiln shell in the prior art; Figure 3 This is a schematic diagram of the structure of the fired belt in this embodiment; Figure 4 for Figure 3 A magnified view of a section at point A in the middle; Figure 5 This is a schematic diagram of the preheating zone cylinder and the cooling zone cylinder in this embodiment.

[0021] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Detailed Implementation

[0022] The present invention will now be further described with reference to the accompanying drawings. Example

[0023] like Figure 3 and Figure 4As shown in the figure, the rotary kiln of this embodiment has a composite lining structure. The rotary kiln has a cylinder, which includes a preheating zone cylinder 20, a firing zone cylinder 10 and a cooling zone cylinder connected in sequence. During operation, the temperature inside the firing zone cylinder 10 is the highest, which can reach about 1750°C. The temperature of the preheating zone cylinder 20 and the cooling zone cylinder is lower, generally 120-150°C.

[0024] During the construction process, anchors 35 are first welded to the inner wall of the fired strip cylinder 10. Then, a layer of refractory felt 33 is laid along the inner wall of the fired strip cylinder 10 within the gaps between the anchors 35. The inner wall of the fired strip cylinder 10 and the refractory felt 33 are bonded together with special refractory mortar. Next, a layer of calcium silicate board 32 is bonded to the refractory felt 33 with special refractory mortar. Then, a waterproofing agent is applied to the calcium silicate board 32. The first casting layer 31 is then constructed, followed by a layer of refractory bricks 34. It should be noted that the height of the anchors 35 must not exceed the upper surface of the first casting layer 31.

[0025] By setting the anchor 35, it is equivalent to adding several support legs between the firing belt cylinder 10 and the first casting layer 31, which plays a supporting role for the first casting layer 31 and increases its strength.

[0026] In this embodiment, the thickness of the first casting layer 31 is not less than 270 mm, and the thickness of the refractory brick layer 34 is not less than 230 mm. This results in a total lining thickness of not less than 500 mm, and the total weight of the lining is not only not increased compared to the previous version, but is actually reduced. This is because the first casting layer 31 uses high-strength lightweight castable and incorporates a 150 mm thick refractory felt 33 and a calcium silicate board 32. These materials are not only lightweight but also have extremely low thermal conductivity.

[0027] The refractory felt 33 and calcium silicate board 32 have low thermal conductivity and significant heat insulation effect, but low strength. Therefore, anchors 35 are installed in the first cast layer 31. The mesh structure formed by the anchors 35 is sufficient to support the weight and stress of the first cast layer 31 without cracking or damage. Thus, the refractory felt 33 and calcium silicate board 32 only serve as filling and insulation, and do not need to support the first cast layer 31, extending its service life.

[0028] To ensure that the first casting layer 31 has sufficient strength and low shrinkage to support the pressure and shear force exerted on it by the refractory brick layer 34 and the kiln body at high temperatures, the first casting layer 31 should be ignited and heated to ensure sintering after construction. The sintering temperature is usually around 1500℃, and the baking time is about 7 days.

[0029] like Figure 5As shown, the preheating zone cylinder 20 and the cooling zone cylinder have the same structure, and both are internally constructed with a second casting layer 30 and a third casting layer 40 sequentially. The formulations and functions of the second casting layer 30 and the third casting layer 40 are different. The function of the second casting layer 30 is heat insulation, while the function of the third casting layer 40 is heat resistance and wear resistance. The second casting layer 30 is constructed first, and the third casting layer 40 is constructed after it dries. The formulations of both are existing conventional technologies, and will not be described in detail in this embodiment.

[0030] The traditional single refractory brick masonry has been replaced by double-layer composite castable masonry, which can reduce the maximum surface heat dissipation temperature of the outer cylinder of the preheating zone and cooling zone of the rotary kiln from the current 220℃ and 198℃ to below 120℃ and 150℃ respectively.

[0031] Preliminary estimates suggest that using this type of rotary kiln can save approximately 191 kg of standard coal per unit product. At the same time, by reducing the heat dissipation temperature of the outer cylinder of the rotary kiln, it not only improves the high-temperature working environment for employees but also reduces pollutant emissions in the exhaust gas.

[0032] This novel composite lining structure for rotary kilns using refractory materials fundamentally solves the defects and drawbacks of traditional masonry methods, offering significant economic and social benefits. Its masonry method is consistent with the existing method for "traditional single refractory brick or cast-in-place layer" masonry, and will not be detailed in this embodiment.

[0033] The above embodiments are not intended to limit the shape, material, structure, etc. of this utility model in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this utility model shall fall within the protection scope of this utility model.

[0034] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this utility model and to simplify 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 the scope of protection of this utility model.

[0035] If the terms "first" or "second" are used in this document to define the components, those skilled in the art should know that the use of "first" or "second" is merely for the convenience of describing this utility model and simplifying the description, and unless otherwise stated, the above terms have no special meaning.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A composite lining structure for a rotary kiln, the rotary kiln having a cylindrical body comprising a preheating zone cylindrical body, a firing zone cylindrical body, and a cooling zone cylindrical body connected in sequence, characterized in that, The firing zone cylinder is lined with a first casting layer, and the first casting layer is lined with a refractory brick layer.

2. The composite lining structure of the rotary kiln according to claim 1, characterized in that, A refractory felt is also laid between the firing belt cylinder and the first casting layer.

3. The composite lining structure of the rotary kiln according to claim 2, characterized in that, A calcium silicate board is also laid between the refractory felt and the first casting layer.

4. The composite lining structure of the rotary kiln according to claim 1, characterized in that, Anchors are also provided inside the firing belt cylinder.

5. The composite lining structure of the rotary kiln according to claim 1, characterized in that, The thickness of the first casting layer is not less than 270 mm.

6. The composite lining structure of the rotary kiln according to claim 1, characterized in that, The thickness of the refractory brick layer shall not be less than 230 mm.

7. The composite lining structure of the rotary kiln according to claim 1, characterized in that, The preheating zone cylinder and the cooling zone cylinder have the same structure, and a second casting layer and a third casting layer are sequentially built inside the preheating zone cylinder and the cooling zone cylinder.

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