A kind of iron phosphate drying rotary kiln

Abstract

The utility model relates to an iron phosphate drying rotary kiln, which belongs to the technical field of rotary kilns. The kiln body includes an inner cylinder, a buffer layer, an insulating layer, an outer cylinder and a connecting piece; the insulating layer is a cylindrical body made of a heat-insulating material, the outer side of the insulating layer contacts the outer cylinder, the inner side of the insulating layer contacts the buffer layer, and the inner side of the buffer layer contacts the inner cylinder; the connecting piece is connected to the inner wall of the outer cylinder, and the connecting piece passes through the layered structure inside the outer cylinder. The utility model can reduce system energy consumption, reduce the surface temperature of the kiln body, avoid cracking of the rotary kiln cylinder, and has no pollution to iron phosphate, thereby ensuring product quality.

Description

Technical Field

[0001] The utility model relates to the technical field of rotary kilns, in particular to an iron phosphate drying rotary kiln. Background Art

[0002] Iron phosphate is mainly used in the manufacture of lithium iron phosphate battery materials, catalysts and ceramics. The product has the characteristics of moderate specific surface area, narrow iron-phosphorus ratio range and good batch stability.

[0003] The iron phosphate rotary kiln equipment is used for the continuous dehydration of the crystal water and free water of iron phosphate powder. The iron phosphate dihydrate is directly fed into the rotary kiln, and the crystal water in the iron phosphate dihydrate is removed at high temperature to form iron phosphate powder. The heating temperature of the rotary kiln is 550-700℃, and the treatment time of each batch of iron phosphate in the rotary kiln is 2-5 hours.

[0004] The rotary kiln cylinder is usually made of heat-resistant and corrosion-resistant metal materials. In order to ensure production safety, it needs to be cooled by circulating cooling water, and the system has high energy consumption. For example, the application number is 202410093103.0, and the name is a lithium iron phosphate sintering preparation system using an electric atmosphere rotary kiln. It is equipped with multiple spray ports for connecting to the cooling water pipeline; during operation, the internal temperature of the kiln body is as high as 550-700°C, and the temperature of the outer wall is sprayed with cooling water, which is easy to cause cracks in the weld due to thermal expansion and contraction, and the service life is short. Utility Model Content

[0005] In order to solve the above technical problems, the utility model provides a rotary kiln for drying iron phosphate, the purpose of which is to change the structure of the rotary kiln for drying iron phosphate, reduce system energy consumption, reduce the surface temperature of the kiln body, reduce the probability of cracking of the rotary kiln cylinder, and have no pollution to the iron phosphate, thereby ensuring product quality.

[0006] In order to achieve the above purpose, the technical solution of the utility model is:

[0007] A ferric phosphate drying rotary kiln, the kiln body comprising an inner cylinder, a buffer layer, an insulation layer, an outer cylinder and connecting parts;

[0008] The insulation layer is a cylindrical body made of insulation material, the outer side of the insulation layer contacts the outer cylinder, the inner side of the insulation layer contacts the buffer layer, and the inner side of the buffer layer contacts the inner cylinder; the connecting piece is connected to the inner wall of the outer cylinder, and the connecting piece passes through the layered structure inside the outer cylinder.

[0009] The utility model changes a conventional metal rotary kiln into a structure in which a heat insulating layer is provided in the middle of a double-layer wall. The heat insulating layer isolates heat transfer. After being blocked by the heat insulating layer, the temperature of the outer cylinder body is reduced, and the use of cooling water can be reduced. When the thickness of the heat insulating layer is increased, cooling water circulation cooling is no longer required, thereby saving system energy consumption. In addition, because the temperature difference between the inner and outer sides of the inner cylinder body and the outer cylinder body is not large, the state of the inner wall of a single kiln body being high temperature and the outer wall being low temperature in the prior art is no longer there, the probability of expansion and cracking of the weld is small, and the service life is long.

[0010] The inner cylinder and the insulation material are different materials with different expansion coefficients. They cannot fit closely with each other under such a large temperature difference from room temperature to 700℃. Especially in the actual production process, there are still a lot of iron phosphate materials to be processed in the rotary kiln. The inner cylinder and the insulation layer will produce certain deformation, and the inner cylinder and the insulation material will produce mutual friction and extrusion, which will cause rapid wear of the inner cylinder and the insulation material and affect the service life of the rotary kiln. Setting a buffer layer can greatly reduce this mutual extrusion and friction state, effectively release deformation stress, further extend the service life, and still maintain the stability of the overall structure of the kiln after the kiln body is divided into multiple layers.

[0011] Furthermore, the heat insulating layer is divided into a heat insulating portion and a heat cutting portion along the radial direction of the kiln body, the heat cutting portion is in contact with the outer cylinder, and the heat insulating portion is located between the heat cutting portion and the buffer layer.

[0012] The flexural strength of the insulation part is ≥5MPa, and the compressive strength is ≥30MPa.

[0013] The utility model not only needs to consider the heat insulation performance, but also needs to consider the structural strength of the rotary kiln, and has certain requirements on the flexural strength and compressive strength of the insulation part. Therefore, the insulation part must have a certain strength, while the heat-cutting part has a moderate heat insulation performance.

[0014] Furthermore, the kiln body is divided into a heating section and a constant temperature section along its length direction.

[0015] The discharge end of the rotary kiln is heated by natural gas combustion, and the feed end is operated under negative pressure. In order to improve the balance of the rotary kiln's life and reduce production costs, it is divided into two sections according to working conditions, and different materials are used for production. The heating section (the end where natural gas is burned) requires stronger resistance to temperature shock, while the constant temperature section can use materials with relatively lower resistance to temperature shock, which is suitable for working conditions in different regions, improves the balance of the rotary kiln's life, and reduces equipment costs.

[0016] Furthermore, the insulation material of the heating section is mullite castable, and the insulation material of the constant temperature section is high-strength microporous insulation material; the heat-cutting part is a prefabricated heat-cutting block.

[0017] Furthermore, the thickness of the heat insulation part is 150 mm to 250 mm, the thickness of the heat blocking part is 30 mm to 50 mm, and the thickness of the buffer layer is 5 mm to 10 mm.

[0018] By specifically allocating the thickness of the insulation part and the heat-cutting part, the overall strength of the kiln body is ensured while the temperature of the outer cylinder is kept below 60°C. This makes the temperature of the outer cylinder meet production requirements, eliminates cooling water circulation, and further reduces equipment costs and production energy consumption. The thickness of the buffer layer enables stress release between the inner cylinder and the insulation layer.

[0019] Furthermore, the insulation layer includes a preform and a cast body, each cast body and preform includes an insulating part and a heat-cutting part, the preforms are connected in an array on the inner wall of the outer cylinder, and there is a cast body between every two adjacent preforms, and the cast body is respectively connected to the two preforms and the inner wall of the outer cylinder between the two preforms.

[0020] The preform and the cast body are made of the same material. The preform and the cast body distributed along the circumference of the kiln body are spaced apart to form a cylindrical insulation layer. The spaced apart preform and the cast body can facilitate the masonry of the rotary kiln. Compared with other masonry methods in the prior art, the construction is more convenient, and the connection between the masonry structure and the outer cylinder is tighter after construction.

[0021] Furthermore, the buffer layer is a layered structure formed by paving fiber materials.

[0022] The use temperature of the fiber material is higher than 700° C., and the material compression rate is 10% to 20%.

[0023] The inner cylinder and the insulation material are different materials with different expansion coefficients. They cannot fit closely with each other under such a large temperature difference from room temperature to 700℃. Especially in the actual production process, there are still a lot of iron phosphate materials to be processed in the rotary kiln. The inner cylinder and the insulation layer will produce certain deformation, and the inner cylinder and the insulation material will produce mutual friction and extrusion, which will cause rapid wear of the inner cylinder and the insulation material and affect the service life of the rotary kiln. Setting a buffer layer can greatly reduce this mutual extrusion and friction state, and can effectively release deformation stress. The 5mm to 10mm buffer layer can effectively compensate for the thermal expansion deformation of the inner cylinder from room temperature to 700℃.

[0024] Furthermore, the buffer layer is a cylinder made of aluminum silicate fiber paper.

[0025] The utility model preferably uses aluminum silicate fiber paper because aluminum silicate fiber paper also has the characteristics of low thermal conductivity, thermal conductivity (800°C) ≤ 0.05 (W / mk), high temperature shrinkage (1000°C, 24h) ≤ 3%, which is very suitable for use in the utility model to assist in heat insulation.

[0026] Furthermore, the connecting part includes anchor nails, screws and nuts. The preform is fixedly connected to the outer cylinder. The inner wall of the outer cylinder between two adjacent preforms is connected with anchor nails and screws. The screw passes through the inner cylinder and is connected with a nut. The entire anchor nail and the middle part of the screw are fixed by the casting body.

[0027] The anchor nails and screws connect the thermal insulation layer to the outer cylinder, and the screws are also used to connect to the inner cylinder.

[0028] Furthermore, the inner cylinder is a cylinder made of stainless steel.

[0029] Stainless steel has relatively stable physical and chemical properties at 700°C and does not react with iron phosphate, thus ensuring the normal production of iron phosphate and avoiding the introduction of impurities.

[0030] Through the above technical solution, the beneficial effects of the utility model are:

[0031] The utility model changes the conventional metal rotary kiln into a structure with a heat insulating layer in the middle of the double wall. The heat insulating layer blocks the heat transfer, so that the temperature of the outer cylinder is lower than 60°C, which can reduce or even eliminate the need for cooling water circulation cooling, saves system energy consumption, and reduces the probability of kiln cracking.

[0032] Compared with other masonry structures in the prior art, the special insulation layer structure of the utility model is more convenient to construct, and the connection between the masonry structure and the outer cylinder is tighter after construction.

[0033] The main purpose of the inner cylinder of the utility model is to separate the iron phosphate from the insulation layer to prevent the iron phosphate from being contaminated when the insulation layer contacts the iron phosphate. The inner cylinder made of stainless steel is still stable at a high temperature of 550°C to 700°C, will not contaminate the iron phosphate, and ensure product quality.

[0034] The utility model is provided with a buffer layer, and the buffer layer is provided between the heat insulating layer and the inner cylinder body, which can effectively eliminate structural stress and thermal stress, delay the wear of the inner cylinder body, and effectively protect the heat insulating layer, thereby extending the service life of the equipment.

[0035] The utility model changes the masonry structure and can reduce the production cost and production difficulty under the premise of meeting various parameter indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of the utility model;

[0037] Figure 2 yes Figure 1 AA section view;

[0038] Figure 3 yes Figure 2 Enlarged view of part B.

[0039] The numbers in the attached figure are: 1. Kiln head shrinkage; 2. Kiln tail shrinkage; 3. Inner cylinder; 4. Insulation layer; 5. Outer cylinder; 6. Connector; 7. Buffer layer; 8. Prefabricated body; 9. Casting body; 10. Insulation part; 11. Heat cut-off part; 12. Constant temperature section; 13. Heating section; 14. Anchor nail; 15. Screw; 16. Nut. DETAILED DESCRIPTION

[0040] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments:

[0041] like Figure 1 As shown, a ferrous phosphate drying rotary kiln includes a kiln body and a driving assembly, wherein the kiln body has a kiln head necking 1 and a kiln tail necking 2, and the kiln body includes an inner cylinder 3, an insulating layer 4 and an outer cylinder 5, wherein the inner cylinder 3 is a cylindrical body made of stainless steel, and the outer cylinder 5 is a cylindrical body made of steel plate or other metals, wherein the insulating layer 4 is located between the inner cylinder 3 and the outer cylinder 5, and the inner cylinder 3 and the outer cylinder 5 are connected by a connecting piece 6, and the connecting piece 6 runs through the layered structure between the inner cylinder 3 and the outer cylinder 5, and a buffer layer 7 is provided between the inner cylinder 3 and the insulating layer 4.

[0042] The buffer layer 7 is composed of one of the materials selected from aluminum silicate fiber paper, ceramic fiber paper, alumina fiber, silicon carbide fiber, rock wool, basalt, etc. Aluminum silicate fiber paper is also called high temperature resistant fiber paper, which is an industrial material with excellent performance. High-purity aluminum silicate fiber is the most preferred material. The aluminum silicate fiber is laid along the outer wall of the inner cylinder in a cylindrical shape. It is processed from high-purity aluminum silicate fiber and has the characteristics of low thermal conductivity, high temperature resistance, and flexibility. The thermal conductivity coefficient (800°C) is ≤0.05 (W / mk), and the high temperature shrinkage rate is (1000℃, 24h)≤3%, and the aluminum silicate fiber paper can produce a certain deformation when compressed, and even produce a certain relative slip state, which has a buffering effect on the thermal expansion of the inner cylinder, and is extremely suitable for use in the present utility model. Ceramic fiber paper or rock wool and other high temperature resistant materials that can produce a certain deformation can also be selected. The "certain" here specifically refers to the expansion amount that satisfies the time when the inner cylinder is heated from room temperature to 700℃, which is suitable for the thermal expansion deformation of the inner cylinder 3 and the insulation layer 4. The material compression rate is usually 10% to 20%.

[0043] like Figure 2 and Figure 3 As shown, the insulation layer 4 includes a preform 8 and a cast body 9, which are divided into several equal parts along the circumferential direction according to the diameter of the kiln body, each of which includes a preform 8 and a cast body 9, and the preform 8 and the cast body 9 are arranged at intervals to form a cylindrical insulation layer 4, and the preform 8 and the cast body 9 each include an insulation part 10 and a heat cut-off part 11, and the heat cut-off part 11 faces the outer cylinder 5, and the insulation part 10 faces the inner cylinder 3.

[0044] According to the working conditions of the rotary kiln, the kiln body is divided into a constant temperature section 12 and a heating section 13 along the length direction. The preform 8 and the casting body 9 of the heating section 13 are made of the same material, and the preform 8 and the casting body 9 of the constant temperature section 12 are made of the same material.

[0045] For the cast body: the heat insulation part 10 of the heating section 13 is made of mullite castable material, the heat insulation part 10 of the constant temperature section 12 is made of high-strength microporous heat insulation castable material, and the heat cut-off part 11 adopts a prefabricated heat cut-off block.

[0046] For the preforms: the preform 8 of the heating section 13 is a preform made by layered casting of mullite castable material and heat cut-off block, and the preform 8 of the constant temperature section 12 is a preform made by layered casting of high-strength microporous heat insulation castable material and heat cut-off block.

[0047] The mullite castable material: Al2O3 content ≥ 60wt%, volume density ≥ 2.3 (g / cm 3 ), flexural strength (1150℃×3h)≥10Mpa, compressive strength (1150℃×3h)≥60Mpa, thermal conductivity≤0.5W / mk(1000℃).

[0048] The high-strength microporous thermal insulation castable has an Al2O3 content of ≥ 45% by weight and a bulk density of ≥ 1.8 (g / cm 3 ), flexural strength (1150℃×3h)≥5Mpa, compressive strength (1150℃×3h)≥30Mpa, and thermal conductivity at an average of 0.026~0.015W / m·k (500℃).

[0049] The heat block casting material: SiO2 content 60wt% ~ 80wt%, volume density ≤ 0.6 (g / cm 3 ) The maximum operating temperature is ≥1100℃, the thermal conductivity (800℃) is ≤0.05 (W / mk), and the heat-insulating block is preferably a gradient heat-insulating material. The preparation method of the heat-insulating block comprises: (a) mixing lightweight mullite balls with a premix for 3min to 5min, and then adding water for wet mixing for 5min to 10min to obtain a slurry; (b) placing the slurry in a mold and vibrating it to obtain a block; and wet curing the block; wherein the preparation of the premix comprises: mixing alumina powder, silicon powder and a binder to obtain a premix.

[0050] The thickness of the masonry structure (prefabricated body and cast body) is 200mm-300mm, the thickness of the buffer layer 7 is 5mm-10mm, the thickness of the heat insulation part 10 is 150mm-250mm, and the thickness of the heat cut-off part 11 is 30mm-50mm.

[0051] Each of the preforms 8 is a cuboid or an isosceles trapezoid.

[0052] Each casting body 9 has a cross section of an isosceles trapezoid that is small inside and large outside.

[0053] The preform 8 is fixedly connected to the outer cylinder 5. Anchor nails 14 and screws 15 are connected to the inner wall of the outer cylinder 5 between two adjacent preforms 8. The screw 15 passes through the inner cylinder 3 and is connected to a nut 16. The entire anchor nail 14 and the middle part of the screw 15 are fixed by the casting body 9.

[0054] The screw rod 15 and the nut 16 jointly connect the outer cylinder 5 and the inner cylinder 3 .

[0055] The anchor nail 14, the screw rod 15 and the nut 16 are all made of stainless steel.

[0056] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Various modifications may be made to the technical solution of the present invention without violating the spirit of the present invention, that is, within the scope of disclosure.

Claims

1. A ferric phosphate drying rotary kiln, comprising a kiln body, characterized in that: The kiln body comprises an inner cylinder (3), a buffer layer (7), an insulation layer (4), an outer cylinder (5) and a connecting piece (6); The heat insulating layer (4) is a cylindrical body made of a heat insulating material, the outer side surface of the heat insulating layer (4) contacts the outer cylinder (5), the inner side surface of the heat insulating layer (4) contacts the buffer layer (7), and the inner side surface of the buffer layer (7) contacts the inner cylinder (3); the connecting piece (6) is connected to the inner wall of the outer cylinder (5), and the connecting piece (6) passes through the layered structure inside the outer cylinder (5).

2. The iron phosphate drying rotary kiln according to claim 1, characterized in that: The heat insulating layer (4) is divided into a heat insulating portion (10) and a heat cut-off portion (11) along the radial direction of the kiln body, the heat cut-off portion (11) is in contact with the outer cylinder, and the heat insulating portion (10) is located between the heat cut-off portion (11) and the buffer layer (7).

3. The iron phosphate drying rotary kiln according to claim 2, characterized in that: The kiln body is divided into a heating section (13) and a constant temperature section (12) along its length direction.

4. The iron phosphate drying rotary kiln according to claim 3, characterized in that: The material of the heat insulating part (10) of the heating section (13) is mullite castable, and the material of the heat insulating part (10) of the constant temperature section (12) is high-strength microporous heat insulating material; the heat cut-off part (11) is a prefabricated heat cut-off block.

5. The iron phosphate drying rotary kiln according to claim 4, characterized in that: The thickness of the heat insulating part (10) is 150 mm to 250 mm, the thickness of the heat blocking part (11) is 30 mm to 50 mm, and the thickness of the buffer layer is 5 mm to 10 mm.

6. The iron phosphate drying rotary kiln according to claim 1, characterized in that: The thermal insulation layer (4) comprises a preform (8) and a cast body (9); the preforms (8) are connected in an array on the inner wall of the outer cylinder (5); a cast body (9) is provided between every two adjacent preforms (8); and the cast body (9) is respectively connected to the two preforms (8) and the inner wall of the outer cylinder between the two preforms (8).

7. The iron phosphate drying rotary kiln according to claim 1, characterized in that: The buffer layer (7) is a layered structure formed by laying out fiber materials.

8. The iron phosphate drying rotary kiln according to claim 7, characterized in that: The buffer layer (7) is a cylindrical body made of aluminum silicate fiber paper.

9. The iron phosphate drying rotary kiln according to claim 1, characterized in that: The connecting member (6) comprises an anchoring nail (14), a screw rod (15) and a nut (16); the preform (8) is fixedly connected to the outer cylinder (5); the inner wall of the outer cylinder (5) between two adjacent preforms (8) is connected with the anchoring nail (14) and the screw rod (15); the screw rod (15) passes through the inner cylinder (3) and is connected with the nut (16); the entire anchoring nail (14) and the middle part of the screw rod (15) are fixed by the casting body (9).

10. The iron phosphate drying rotary kiln according to claim 1, characterized in that: The inner cylinder (3) is a cylinder made of stainless steel.

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