Aluminum hydroxide electric calcination and water-rich waste heat comprehensive recovery device and use method thereof

Abstract

This invention belongs to the field of aluminum hydroxide roasting technology, specifically a device for the electric roasting of aluminum hydroxide and the comprehensive recovery of waste heat from water-rich environments, and its usage method. It mainly includes an electrically heated drying furnace for high-temperature drying of aluminum hydroxide and an electrically heated roasting furnace for roasting the dried aluminum hydroxide to obtain high-temperature alumina. The outlet of the electrically heated drying furnace is connected to a dust filter, which filters aluminum hydroxide powder from the water vapor discharged during the drying of aluminum hydroxide in the electrically heated drying furnace. The outlet of the electrically heated roasting furnace is connected to a high-temperature alumina waste heat recovery unit, which recovers the heat from the high-temperature alumina obtained by roasting aluminum hydroxide in the electrically heated roasting furnace. This invention uses electricity as a heat source, replacing traditional fossil fuels, and eliminating dust, SO2, and NO generated during combustion at the source. X These air pollutants significantly reduce the carbon emission intensity per unit of product.

Description

Technical Field

[0001] This invention belongs to the field of aluminum hydroxide roasting technology, specifically an aluminum hydroxide electric roasting and water-rich waste heat comprehensive recovery device and its usage method. Background Technology

[0002] The energy consumption level of alumina production directly affects the industry's economic benefits and carbon emission intensity. In the alumina production process, the aluminum hydroxide roasting process is one of the key energy-consuming steps, accounting for approximately 30% of the total energy consumption. Current roasting processes typically involve placing aluminum hydroxide with a moisture content of 5%–8% at approximately 1100°C. o The alumina is calcined at high temperature (C) to remove attached water and crystal water, and to achieve a crystal transformation of Al2O3, ultimately producing a finished alumina product that meets quality requirements.

[0003] Currently, the most commonly used aluminum hydroxide roasting furnaces in industry are gaseous suspension roasting furnaces, which typically use fossil fuels such as coal gas or natural gas and their derivatives as fuel. This process has the following problems in actual operation:

[0004] (1) The furnace equipment uses fossil fuels, resulting in high carbon emissions per unit of alumina product and a significant carbon footprint; at the same time, its combustion process is accompanied by dust, SO2 and NO. X The emission of air pollutants such as pollutants puts significant pressure on environmental governance, making it difficult to meet the current requirements for green and low-carbon development in the industry.

[0005] (2) The large amount of dust-laden wet steam generated during the roasting process lacks effective means of collection and reuse, and the latent heat of vaporization and water resources cannot be fully recovered, resulting in low system thermal efficiency and waste of resources.

[0006] (3) The degree of waste heat recovery and utilization of high-temperature flue gas is insufficient, and the level of energy cascade utilization is limited, resulting in a large space for energy saving and consumption reduction in the overall process.

[0007] Therefore, developing a novel roasting system that combines low emissions with efficient waste heat recovery is of great practical significance. Summary of the Invention

[0008] In view of the shortcomings of existing aluminum hydroxide roasting processes, which rely on fossil energy, have high carbon emission intensity, and fail to effectively recover water-rich waste heat, the purpose of this invention is to provide a low-energy-consumption, low-carbon aluminum hydroxide electric roasting and water-rich waste heat integrated recovery device and its usage method, so as to achieve a clean energy structure transformation and maximize the cascade utilization of energy.

[0009] The technical solution adopted in this invention is:

[0010] An integrated device for the electric roasting of aluminum hydroxide and the recovery of waste heat from water-rich processes includes: an aluminum hydroxide silo for quantitatively supplying aluminum hydroxide; an electric heating drying furnace for high-temperature drying of aluminum hydroxide; and an electric heating roasting furnace for roasting the dried aluminum hydroxide to obtain high-temperature alumina. The outlet of the electric heating drying furnace is connected to a dust filter, which filters aluminum hydroxide powder from the water vapor discharged during the drying of aluminum hydroxide in the electric heating drying furnace. The outlet of the electric heating roasting furnace is connected to a high-temperature alumina waste heat recovery unit, which recovers heat from the high-temperature alumina obtained by roasting aluminum hydroxide in the electric heating roasting furnace.

[0011] Furthermore, the aluminum hydroxide silo is a steel silo formed by a fixed connection between an upper cylindrical part and a lower conical part. The discharge port at the bottom of the aluminum hydroxide silo is connected to the feed port of the electric heating drying furnace in sequence through a star-shaped unloading valve and a weighing feeder.

[0012] Furthermore, the electric heating drying oven includes: a drying oven shell, a drying oven electric heating rod, and a drying oven fluidized steam nozzle; the drying oven shell is arranged at an incline, the drying oven electric heating rod is set on the top wall inside the drying oven shell, located inside the drying oven shell, an air distribution plate is provided on the bottom wall of the drying oven shell, and multiple drying oven fluidized steam nozzles communicating with the air distribution plate are provided on the bottom wall of the drying oven shell;

[0013] Furthermore, the air distribution plate includes: a plate body and multiple air caps, wherein the plate body is made of heat-resistant steel plate and a refractory material layer is cast on its surface; multiple air caps are densely arranged on the plate body; an air chamber is formed inside the plate body, and the air chamber is connected to the fluidized steam nozzle of the drying oven.

[0014] Furthermore, the electric heating drying oven includes: an inclined roasting furnace shell and roasting furnace electric heating rods disposed on the inner top wall of the roasting furnace shell;

[0015] Furthermore, the high-temperature alumina waste heat recovery device includes: a waste heat recovery device shell and a waste heat recovery device heat exchange coil. The waste heat recovery device heat exchange coil is spirally wound from bottom to top and embedded in the waste heat recovery device shell. The waste heat recovery device heat exchange coil uses water as the heat carrier and uses a counter-current heat exchange method to exchange heat with the high-temperature alumina located in the waste heat recovery device shell.

[0016] Furthermore, the dust filter includes: a dust filter housing, a metal filter cartridge, and a gravity flap valve. The dust filter housing has an air inlet, an air outlet, and a material outlet. The metal filter cartridge is fixedly installed inside the dust filter housing. A gravity flap valve is installed inside the material outlet of the dust filter housing.

[0017] Furthermore, the outlet of the dust filter is connected to a centrifugal compressor, which is used to pressurize the clean water vapor. The outlet of the centrifugal compressor is connected to the fluidized steam nozzle of the electric heating drying oven through a pressure reducing valve.

[0018] The method of using the above-mentioned device includes the following:

[0019] First, the hydrated aluminum hydroxide in the aluminum hydroxide silo is quantitatively transferred to an electrically heated drying oven. The aluminum hydroxide is then dried at high temperature (400-600°C) to remove adhering water and some of the water of crystallization, thus forming dried aluminum hydroxide. o C; Then, the dried aluminum hydroxide is discharged into an electrically heated calcining furnace for high-temperature decomposition to remove residual water of crystallization, generating high-temperature alumina. The calcination temperature is 600~1000℃. o C. The water vapor generated during the roasting process is discharged into the electric heating drying furnace; finally, the high-temperature alumina is discharged into the high-temperature alumina waste heat recovery unit to recover the heat in the high-temperature alumina; during the process, the dust-containing water vapor discharged from the electric heating drying furnace is purified by a dust fine filter, and the aluminum hydroxide dust captured by the dust fine filter is discharged back into the electric heating roasting furnace.

[0020] Furthermore, after being purified by the dust filter, the water vapor is pressurized to 0.4~0.8MPa by a centrifugal compressor to obtain pressurized steam. The pressurized steam is used for external supply or is returned to the electric heating drying oven as a fluidizing medium after being depressurized by a steam pressure reducing valve.

[0021] Compared with aluminum hydroxide roasting furnaces that use conventional fossil fuels, the present invention has the following advantages:

[0022] (1) This invention uses electricity as a heat source, replacing traditional fossil fuels, thus eliminating dust, SO2 and NO generated during combustion from the source. X It significantly reduces carbon emission intensity per unit of product by eliminating air pollutants such as carbon dioxide, which aligns with the "dual carbon" strategic goal.

[0023] (2) This invention effectively overcomes the technical defects of the traditional aluminum hydroxide “gas-solid” calcination system in terms of material and energy transmission, such as low heat transfer efficiency, significant transport pulsation, and poor system operation stability.

[0024] (3) This invention not only recovers the sensible heat of high-temperature alumina, but also comprehensively recovers and utilizes the high-temperature dust-laden wet steam generated during the roasting process, achieving "near-zero emissions" and resource reuse of latent heat of vaporization, water resources and material dust, and greatly improving the thermal efficiency of the system.

[0025] (4) The present invention uses low-pressure steam as the output form of waste heat recovery, which broadens the application scenarios and scope of thermal energy utilization.

[0026] (5) This invention breaks through the constraints of electricity price factors and can effectively adapt to "green electricity" resources such as solar energy and wind energy, providing a clean and sustainable process path for the alumina industry. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an aluminum hydroxide electric roasting and water-rich waste heat comprehensive recovery device according to the present invention.

[0028] In the diagram: 1. Aluminum hydroxide silo; 2. Rotary rotary valve; 3. Weighing feeder; 4. Electric heating drying oven; 5. Electric heating calcining oven; 6. High-temperature alumina waste heat recovery unit; 7. Dust filter; 8. Centrifugal compressor; 9. Steam pressure reducing valve;

[0029] 41. Drying oven outer shell; 42. Drying oven electric heating rod; 43. Drying oven fluidized steam nozzle;

[0030] 51. Roasting furnace outer shell; 52. Roasting furnace electric heating rod;

[0031] 61. Waste heat recovery unit casing; 62. Waste heat recovery unit heat exchange coil;

[0032] 71. Dust filter housing; 72. Metal filter cartridge; 73. Gravity flap valve. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute any limitation on the invention.

[0034] First, such as Figure 1 As shown, this invention provides an aluminum hydroxide electric roasting and water-rich waste heat comprehensive recovery device, comprising: an aluminum hydroxide silo 1, a rotary valve 2, a weighing feeder 3, an electric heating drying furnace 4, an electric heating roasting furnace 5, a high-temperature alumina waste heat recovery unit 6, a dust fine filter 7, a centrifugal compressor 8, and a steam pressure reducing valve 9, wherein:

[0035] The aluminum hydroxide silo 1 is used to store aluminum hydroxide with a moisture content of 5% to 8%. In this embodiment, the aluminum hydroxide silo 1 is a steel plate silo formed by a fixed connection between the upper cylindrical part and the lower conical part. The bottom of the aluminum hydroxide silo 1 is provided with a discharge port, and it is connected to the feed end of the weighing feeder 3 through a star-shaped discharge valve 2. That is, by using the cooperation of the star-shaped discharge valve 2 and the weighing feeder 3, the quantitative feeding function of aluminum hydroxide can be realized.

[0036] The feed inlet of the electric heating drying furnace 4 is connected to the discharge end of the weighing feeder 3, that is, the aluminum hydroxide containing water in the aluminum hydroxide silo 1 is discharged into the electric heating drying furnace 4. The electric heating drying furnace 4 is used to remove the surface water and part of the crystal water of aluminum hydroxide.

[0037] In this embodiment, the heating temperature inside the electric heating drying oven 4 is set to 400-600°C. o C, that is, by drying, the surface water and part of the crystal water of aluminum hydroxide are turned into water vapor, and the water vapor is discharged through the exhaust port located at the top of the electric heating drying furnace 4. The discharge port of the electric heating drying furnace 4 is connected to the electric heating calcining furnace 5, so that the dried aluminum hydroxide is discharged into the electric heating calcining furnace 5.

[0038] Furthermore, the electric heating drying furnace 4 is an atmospheric pressure furnace, which is inclined along the direction from the feed inlet to the discharge outlet. The inclination angle can be 5~15° to facilitate the flow of water-containing aluminum hydroxide entering from the weighing feeder 3. In this embodiment, the electric heating drying furnace 4 consists of a drying furnace shell 41, a drying furnace electric heating rod 42, and a drying furnace fluidizing steam nozzle 43.

[0039] Specifically, the outer shell 41 of the drying furnace consists of, from the outside to the inside, a steel plate, a calcium silicate board, and a refractory castable. The outer shell 41 has a feed inlet, a discharge outlet, and a steam exhaust outlet. Multiple electric heating rods 42 serve as the drying heat source and are evenly arranged on the top wall inside the outer shell 41. Inside the outer shell 41, an air distribution plate is provided on the bottom wall of the outer shell 41. At the same time, multiple fluidizing steam nozzles 43 connected to the air distribution plate are provided on the bottom wall of the outer shell 41 to further accelerate the fluidization and transport of the hydrated aluminum hydroxide in the furnace.

[0040] Furthermore, in this embodiment, the air distribution plate includes: a plate body and multiple air caps, wherein the plate body is made of heat-resistant steel plate and a refractory material layer is cast on its surface; multiple air caps are densely arranged on the plate body, and the air caps are preferably bell-shaped structures, but not limited thereto; an air chamber is formed inside the plate body, and the air chamber is connected to the fluidized steam nozzle 43 of the drying furnace; during operation, the gas enters the air chamber through the fluidized steam nozzle 43 of the drying furnace, and is then ejected at high speed through the side holes of the outer cover of each air cap to act on the bed material.

[0041] The feed inlet of the electric heating calcining furnace 5 is connected to the discharge outlet of the electric heating drying furnace 4. The aluminum hydroxide dried in the electric heating drying furnace 4 is then discharged into the electric heating calcining furnace 5. The electric heating calcining furnace 5 is used to remove all the water of crystallization from the aluminum hydroxide. In this embodiment, the heating temperature inside the electric heating calcining furnace 5 is set to 600~1000℃. o C, that is, by high-temperature roasting, all the crystal water in the dried aluminum hydroxide is converted into water vapor, and the water vapor is discharged through the exhaust port located at the top of the electric heating roasting furnace 5;

[0042] Preferably, during the roasting process, the aluminum hydroxide crystal water turns into steam, which can be introduced into the electrically heated drying oven 4 from the fluidized steam nozzle 43 of the drying oven.

[0043] The discharge port of the electric heating calcining furnace 5 is connected to the inlet of the high-temperature alumina waste heat recovery unit 6. This means that the material heated by the electric heating calcining furnace 5 reaches a temperature of 900°C. o The high-temperature alumina of C is discharged into the high-temperature alumina waste heat recovery unit 6;

[0044] Furthermore, the electric heating calcining furnace 5 is an atmospheric pressure furnace. The electric heating calcining furnace 5 is arranged at an inclination along the direction from the feed inlet to the discharge outlet, and the inclination angle can be 5~15° to facilitate the flow of alumina after calcination. In this embodiment, the electric heating calcining furnace 5 consists of a calcining furnace shell 51 and a calcining furnace electric heating rod 52;

[0045] Specifically, the outer shell 51 of the roasting furnace consists of a steel plate, a calcium silicate board and a refractory castable from the outside to the inside. The outer shell 51 of the roasting furnace has a feed inlet, a discharge outlet and a steam outlet. Multiple electric heating rods 52 of the roasting furnace are provided and evenly arranged on the top of the outer shell 51 of the roasting furnace, which serve as the heat source for roasting heating.

[0046] The inlet of the high-temperature alumina waste heat recovery unit 6 is connected to the outlet of the electric heating calcining furnace 5. It is used to recover the sensible heat of the high-temperature alumina; that is, the alumina temperatures entering and exiting the high-temperature alumina waste heat recovery unit 6 are 900°C and 900°C respectively. o C and 100 o C;

[0047] In this embodiment, the high-temperature alumina waste heat recovery unit 6 is composed of a waste heat recovery unit shell 61 and a waste heat recovery unit heat exchange coil 62.

[0048] Specifically, the outer shell 61 of the waste heat recovery unit, from the outside to the inside, consists of: a steel plate, a calcium silicate board, and a refractory castable. The heat exchange coil 62 of the waste heat recovery unit is spirally wound from bottom to top and embedded inside the outer shell 61. The heat exchange coil 62 exchanges heat counter-currently with the high-temperature alumina located inside the outer shell 61. Furthermore, the heat exchange coil 62 adopts a natural circulation principle and uses water as the heat recovery carrier. The structural form is a single-tube co-current spiral heat exchange coil. The inlet water temperature of the heat exchange coil 62 is 50℃, the steam outlet is saturated steam at 0.6MPa, and the design pressure of the heat exchange coil 62 is 1MPa.

[0049] The dust filter 7 is used to filter aluminum hydroxide dust in the water vapor discharged through the exhaust port of the electric heating drying furnace 4, and discharges the filtered aluminum hydroxide dust into the electric heating calcining furnace 5. That is, the air inlet of the dust filter 7 is connected to the exhaust port of the electric heating drying furnace 4, and the discharge port of the dust filter 7 is connected to the feed port of the electric heating calcining furnace 5.

[0050] In this embodiment, the dust filter 7 consists of a dust filter housing 71, a metal filter cartridge 72, and a gravity flap valve 73. Specifically, the dust filter housing 71 has an air inlet, an air outlet, and a discharge outlet. The metal filter cartridge 72 is fixedly installed inside the dust filter housing 71. The gravity flap valve 73 is installed inside the discharge outlet of the dust filter housing 71. That is, the metal filter cartridge 72 is used to filter and collect aluminum hydroxide dust in water vapor. The filtered aluminum hydroxide dust is discharged into the electric heating calcining furnace 5 through the gravity flap valve 73.

[0051] The outlet of the dust filter 7 is connected to the inlet of the centrifugal compressor 8. That is, the clean water vapor filtered by the dust filter 7 is pressurized by the centrifugal compressor 8 and then discharged from the outlet of the centrifugal compressor 8.

[0052] Furthermore, the pressurized steam can be depressurized through the steam pressure reducing valve 9 and sent back to the drying furnace fluidizing steam nozzle 43 of the electric heating drying furnace 4 for fluidizing the material inside the electric heating drying furnace 4.

[0053] In this embodiment, the centrifugal compressor 8 pressurizes the water vapor to superheated steam at 0.6 MPa. Two-thirds of the steam can then be supplied externally, while one-third of the steam can be depressurized by the steam pressure reducing valve 9 and sent back to the drying furnace fluidizing steam nozzle 43 of the electric heating drying furnace 4 for fluidization.

[0054] Secondly, the method of using the above-mentioned aluminum hydroxide electric roasting and water-rich waste heat comprehensive recovery device is as follows:

[0055] S1: Quantitative feeding;

[0056] Aluminum hydroxide with a moisture content of 5% to 8% is stored in aluminum hydroxide silo 1, and then quantitatively fed into the electric heating drying oven 4 through star-shaped discharge valve 2 and weighing feeder 3.

[0057] S2: Dry aluminum hydroxide using an electric heating drying oven 4;

[0058] Specifically, within the electrically heated drying furnace 4, the inclined arrangement of the furnace and the steam entering from the fluidized steam nozzle 43 cause aluminum hydroxide to flow from the inlet to the outlet. During this flow, it is heated by the electric heating rod 42 at the top of the furnace, maintaining the furnace temperature at 400-600°C. oC, so that the surface water and part of the crystal water of aluminum hydroxide are turned into water vapor, which is then discharged through the exhaust port at the top of the furnace.

[0059] S3; High-temperature roasting of 5 pairs of dried aluminum hydroxide in an electrically heated roasting furnace;

[0060] The aluminum hydroxide, dried in the electrically heated drying furnace 4, is discharged into the electrically heated calcining furnace 5. The inclined arrangement of the furnace allows the dried aluminum hydroxide to flow within it. During this flow, it is heated by the electric heating rods 5.2, maintaining the furnace temperature at 600-1000°C. o C. The aluminum hydroxide is calcined at high temperature to remove the remaining water of crystallization in the dried aluminum hydroxide. During the calcination process, the water of crystallization in the aluminum hydroxide is converted into water vapor and introduced into the electrically heated drying furnace 4.

[0061] S4: The sensible heat of the calcined high-temperature alumina is recovered using the high-temperature alumina waste heat recovery device 6.

[0062] The high-temperature alumina calcined in the electric heating calcining furnace 5 is discharged into the high-temperature alumina waste heat recovery unit 6 to recover sensible heat. In the high-temperature alumina waste heat recovery unit 6, water is supplied to exchange heat indirectly with the high-temperature alumina in a countercurrent manner through the spiral heat exchange coil 62, and the generated low-pressure steam is supplied externally.

[0063] S4: Exhaust gas treatment;

[0064] The steam discharged from the electric heating drying furnace 4 enters the dust filter 7 for dust removal and purification, and the collected aluminum hydroxide dust is returned to the electric heating roasting furnace 5 through the gravity flap valve 73. The centrifugal compressor 8 pressurizes the clean steam to 0.6MPa steam. Then, 2 / 3 of the steam is supplied externally, and 1 / 3 of the steam is sent back to the electric heating drying furnace 4 for fluidization after being depressurized by the steam pressure reducing valve 9.

[0065] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural or procedural modifications made based on the content of this specification, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A device for integrated recovery of waste heat from the electric roasting of aluminum hydroxide and the use of water-rich furnace, characterized in that, include: Aluminum hydroxide bin (1) for quantitatively supplying aluminum hydroxide, an electric heating drying furnace (4) for high-temperature drying of aluminum hydroxide, and an electric heating calcining furnace (5) for calcining the dried aluminum hydroxide to obtain high-temperature alumina. The outlet of the electric heating drying furnace (4) is connected to the dust filter (7), which is used to filter aluminum hydroxide powder in the water vapor discharged when aluminum hydroxide is dried by the electric heating drying furnace (4). The discharge port of the electric heating calcining furnace (5) is connected to the high-temperature alumina waste heat recovery device (6), which is used to recover the heat in the high-temperature alumina obtained by calcining aluminum hydroxide in the electric heating calcining furnace (5).

2. The aluminum hydroxide electro-calcination and water-rich waste heat recovery device according to claim 1, characterized in that: The aluminum hydroxide silo (1) is a steel plate silo formed by a fixed connection between the upper cylindrical part and the lower conical part. The discharge port at the bottom of the aluminum hydroxide silo (1) is connected to the feed port of the electric heating drying furnace (4) through the star-shaped unloading valve (2) and the weighing feeder (3) in sequence.

3. The aluminum hydroxide electro-calcination and water-rich waste heat recovery device according to claim 1, characterized in that: The electric heating drying oven (4) includes: a drying oven shell (41), a drying oven electric heating rod (42), and a drying oven fluidized steam nozzle (43). The outer shell (41) of the drying furnace is arranged at an angle. The electric heating rod (42) of the drying furnace is set on the top wall inside the outer shell (41) and located inside the outer shell (41). An air distribution plate is provided on the bottom wall of the outer shell (41), and multiple fluidized steam nozzles (43) of the drying furnace connected to the air distribution plate are provided on the bottom wall of the outer shell (41).

4. The aluminum hydroxide electro-calcination and water-rich waste heat recovery device according to claim 3, characterized in that: The air distribution plate includes: a plate body and multiple air caps. The plate body is made of heat-resistant steel plate and a refractory material layer is cast on its surface. The multiple air caps are densely arranged on the plate body. An air chamber is formed inside the plate body and the air chamber is connected to the fluidized steam nozzle (43) of the drying furnace.

5. The aluminum hydroxide electro-calcination and water-rich waste heat recovery device according to claim 1, characterized in that: The electric heating drying oven (5) includes: an inclined roasting furnace shell (51) and a roasting furnace electric heating rod (52) disposed on the inner top wall of the roasting furnace shell (51).

6. The device for integrated recovery of aluminum hydroxide electrocalcination and water-rich waste heat according to claim 1, characterized in that: The high-temperature alumina waste heat recovery unit (6) includes: a waste heat recovery unit shell (61) and a waste heat recovery unit heat exchange coil (62). The waste heat recovery unit heat exchange coil (62) is spirally wound from bottom to top and embedded in the waste heat recovery unit shell (61). The waste heat recovery unit heat exchange coil (62) uses water as the heat carrier and uses a countercurrent heat exchange method to exchange heat with the high-temperature alumina located in the waste heat recovery unit shell (61).

7. The aluminum hydroxide electro-calcination and water-rich waste heat recovery device according to claim 1, characterized in that: The dust filter (7) includes: a dust filter housing (71), a metal filter cartridge (72), and a gravity flap valve (73). The dust filter housing (71) has an air inlet, an air outlet, and a material outlet. The metal filter cartridge (72) is fixedly installed inside the dust filter housing (71). The gravity flap valve (73) is installed inside the material outlet of the dust filter housing (71).

8. The aluminum hydroxide electric roasting and water-rich waste heat comprehensive recovery device according to claim 7, characterized in that: The outlet of the dust filter (7) is connected to the centrifugal compressor (8), which is used to pressurize the clean water vapor. The outlet of the centrifugal compressor (8) is connected to the fluidized steam nozzle (43) of the electric heating drying oven (4) through the pressure reducing valve (9).

9. A method of using the aluminum hydroxide electric roasting and water-rich waste heat comprehensive recovery device as described in claim 1, characterized in that, Includes the following: First, the hydrated aluminum hydroxide in the aluminum hydroxide silo (1) is quantitatively transported to the electric heating drying furnace (4). After being dried at high temperature in the electric heating drying furnace (4), the attached water and some of the crystal water in the hydrated aluminum hydroxide are removed to form dried aluminum hydroxide. The drying temperature is 400~600℃. o C; Then, the dried aluminum hydroxide is discharged into an electrically heated calcining furnace (5) for high-temperature decomposition to remove residual water of crystallization, generating high-temperature alumina. The calcination temperature is 600~1000℃. o C, the steam generated during the roasting process is discharged into the electric heating drying oven (4); Finally, the high-temperature alumina is discharged into the high-temperature alumina waste heat recovery unit (6) to recover the heat in the high-temperature alumina; During the process, the dust-containing water vapor discharged from the electric heating drying furnace (4) is purified by the dust filter (7), and the aluminum hydroxide dust collected by the dust filter (7) is discharged back into the electric heating roasting furnace (5).

10. The method of using the aluminum hydroxide electric roasting and water-rich waste heat comprehensive recovery device according to claim 9, characterized in that, After being purified by the dust filter (7), the water vapor is pressurized to 0.4~0.8MPa by the centrifugal compressor (8) to obtain pressurized steam. The pressurized steam is used for external supply or is returned to the electric heating drying oven (4) as a fluidizing medium after being depressurized by the steam pressure reducing valve (9).

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