A heat exchange device and heat exchange method for heating aluminum hydroxide using waste heat of aluminum oxide

Abstract

The present invention discloses a heat exchange device and a heat exchange method for heating aluminum hydroxide by utilizing waste heat of aluminum oxide, and relates to the technical field of aluminum oxide roasting, comprising a shell, an outer cylinder is rotatably arranged in the shell, an intermediate cylinder is fixedly arranged in the outer cylinder, an inner cylinder is fixedly arranged in the intermediate cylinder, a first annular cavity is formed between the intermediate cylinder and the outer cylinder, a second annular cavity is formed between the inner cylinder and the intermediate cylinder, a first spiral blade is fixedly arranged in the first annular cavity, a second spiral blade is fixedly arranged in the second annular cavity, and the first spiral blade and the second spiral blade have opposite rotation directions. The present invention can utilize high-temperature aluminum oxide discharged from a cyclone separator to heat aluminum hydroxide, thereby realizing waste heat recovery, and can also utilize high-temperature gas discharged from the cyclone separator to heat aluminum hydroxide, thereby further improving the utilization rate of waste heat and reducing the energy consumption of the main furnace.

Description

Technical Field

[0001] The invention relates to the technical field of alumina roasting, and in particular to a heat exchange device and a heat exchange method for heating aluminum hydroxide using waste heat of alumina. Background Art

[0002] The production process of alumina mainly adopts the Bayer process, sintering process and hybrid process; in the Bayer process, the roasting process is an indispensable process in the production of alumina and is the last process in the entire alumina production. The main task of this production process is to calcine the aluminum hydroxide material with attached water from the decomposition or flat plate at a high temperature in the roasting furnace to remove the attached water and crystal water, thereby generating alumina whose physical and chemical properties meet the requirements of electrolysis;

[0003] For example, in the invention patent with the announcement number CN114754582A, a novel low-temperature roasting system and roasting process of an alumina roasting furnace are disclosed, which includes a roasting main furnace, a first preheating separator, a second preheating separator, a first cooling separator, a second cooling separator, a retention tank and an adjusting device; the material outlet of the second preheating separator is connected to the material inlet of the roasting main furnace through a pipeline, the material outlet of the roasting main furnace is connected to the material inlet of the first preheating separator, the flue gas outlet of the first preheating separator is connected to the flue gas inlet of the second preheating separator, a retention tank is provided at the lower part of the first preheating separator, and an adjusting device is provided at the outlet of the retention tank, the air of the first cooling separator enters the roasting main furnace, and the pipeline at the outlet of the retention tank is connected to the pipeline between the second cooling separator and the first cooling separator;

[0004] However, the alumina and high-temperature gas mixture discharged from the main furnace of the roasting furnace needs to be separated by a cyclone separator. After the alumina is separated by the cyclone separator, its temperature is still above 970°C, which can still reach the roasting temperature of aluminum hydroxide. In order to reduce the energy consumption of the main furnace, developing a heat exchange device that can utilize the waste heat of alumina to roast aluminum hydroxide is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a heat exchange device and a heat exchange method for heating aluminum hydroxide using waste heat from alumina. The high-temperature alumina discharged from a cyclone separator can be used to heat aluminum hydroxide, thereby realizing waste heat recovery. At the same time, the high-temperature gas discharged from the cyclone separator can also be used to heat aluminum hydroxide, further improving the utilization rate of waste heat and reducing the energy consumption of the main furnace.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a heat exchange device for heating aluminum hydroxide using waste heat of aluminum oxide, comprising a shell, an outer cylinder is rotatably arranged in the shell, an intermediate cylinder is fixedly arranged in the outer cylinder, an inner cylinder is fixedly arranged in the intermediate cylinder, the length of the intermediate cylinder is greater than the length of the outer cylinder and less than the length of the inner cylinder, a first annular cavity is formed between the intermediate cylinder and the outer cylinder, and a second annular cavity is formed between the inner cylinder and the intermediate cylinder, a first spiral blade is fixedly arranged in the first annular cavity, a second spiral blade is fixedly arranged in the second annular cavity, and the first spiral blade and the second spiral blade have opposite rotation directions, end ring plates are fixedly installed at both ends of the outer cylinder, the intermediate cylinder and the inner cylinder, the end ring plates are rotatably and sealingly connected to the inner wall of the shell, a first feed port that can be connected to the first annular cavity is opened on one side above the shell, the first feed port is connected to the discharge pipe of the cyclone separator through a pipeline, and the hot aluminum oxide can pass through the first feed port. A second feeding port communicating with the second feeding port is provided on the other side above the shell, and the second feeding port is connected with the main pipeline of the aluminum hydroxide feeding end through a branch pipe. The unheated aluminum hydroxide can enter the second feeding port through the second feeding port, and the aluminum hydroxide in the second feeding port is heated by the hot aluminum oxide in the first feeding port. A second discharging port communicating with the second feeding port is provided on one side below the shell, and a first discharging port communicating with the first feeding port is provided on the other side below the shell. Both ends of the inner cylinder are fixedly connected with extension cylinders, and the extension cylinder extends to the outside of the shell. Both ends of the shell are fixedly provided with rotating joints through a mounting frame. The extension cylinder is connected to the rotating end of the rotating joint, and a flange is installed at the fixed end of the rotating joint. The hot gas discharged from the cyclone separator can enter the inner cylinder through the rotating joint. A filling cylinder is fixedly provided in the inner cylinder through a plurality of connecting rods, and an insulating layer is coated on the inner wall surface of the shell.

[0007] Preferably, a motor is fixedly provided on the outer side of the shell, a large pulley is fixedly provided on the extension tube, a small pulley is fixedly provided on the driving end of the motor, and a belt transmission is used between the large pulley and the small pulley.

[0008] Preferably, the first feed port and the second feed port are both rectangular openings and are connected to a feed hopper on top, the upper end of the feed hopper is circular, and the lower end of the feed hopper is a rectangle that can match the feed port, and the first discharge port and the second discharge port are both connected to a guide hopper below, and an opening is provided on the lower outer side of the guide hopper.

[0009] Preferably, a branch pipe is separated from the main pipe connected to the aluminum hydroxide feeding end, and the branch pipe is connected to the second feed port in the heat exchange device. Part of the aluminum hydroxide can be separated from the main pipe connected to the aluminum hydroxide feeding end through the branch pipe, and the unheated aluminum hydroxide can enter the second annular cavity through the second feed port. The discharge pipe of the cyclone separator is connected to the first feed port in the heat exchange device, and the heated aluminum oxide can enter the first annular cavity through the first feed port. The aluminum hydroxide in the second annular cavity is heated by the heated aluminum oxide in the first annular cavity. The hot gas discharge end of the cyclone separator is connected to the rotary joint at one end of the heat exchange device through an air pipe. The hot gas discharged from the cyclone separator can enter the inner cylinder through the air pipe and the rotary joint to heat the inner cylinder. Finally, the hot gas is discharged through the rotary joint at the other end.

[0010] Preferably, the flow rate of aluminum hydroxide in the branch pipe accounts for 1% to 10% of the total output of the aluminum hydroxide feeding end, and the heat exchange time between the aluminum oxide and aluminum hydroxide in the heat exchange device is 5 minutes to 20 minutes.

[0011] Preferably, when hot air is not used to heat the inner cylinder, a heat-insulating material is filled in the inner cylinder and the extension cylinder is sealed, thereby reducing the dissipation of the temperature of the inner cylinder.

[0012] The present invention provides a heat exchange device and a heat exchange method for heating aluminum hydroxide using waste heat of aluminum oxide, which have the following beneficial effects: the present invention can respectively circulate aluminum oxide and aluminum hydroxide by setting a first annular cavity and a second annular cavity, and heat exchange is achieved by heating the aluminum hydroxide in the second annular cavity with the aluminum oxide in the first annular cavity, and at the same time, the heat exchange area of ​​aluminum oxide and aluminum hydroxide can be increased by the annular cavity to ensure sufficient heat exchange between the two. By having the materials in the first annular cavity and the second annular cavity flow in opposite directions, the inlet side of aluminum oxide can be close to the discharge side of aluminum hydroxide, thereby achieving efficient heat exchange; by connecting the air pipe to a rotary joint, high-temperature gas can be passed into the inner cylinder, and the aluminum hydroxide in the second annular cavity can be heated or kept warm through the inner cylinder; the present invention can utilize the high-temperature aluminum oxide discharged from the cyclone separator to heat the aluminum hydroxide, thereby realizing the recovery of waste heat, and at the same time, can utilize the high-temperature gas discharged from the cyclone separator to heat the aluminum hydroxide, thereby further improving the utilization rate of waste heat and reducing the energy consumption of the main furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A perspective view of the present invention;

[0014] Figure 2 It is the main view of the internal structure of the present invention;

[0015] Figure 3 The main view of the internal structure of the shell;

[0016] Figure 4 It is a three-dimensional diagram of the combination of the outer cylinder, the middle cylinder and the inner cylinder;

[0017] Figure 5 It is the internal structure diagram of the combination of outer cylinder, middle cylinder and inner cylinder;

[0018] Figure 6 It is a schematic diagram of the pipeline connection of the heat exchange method in the present invention.

[0019] In the figure: 1. shell; 2. outer cylinder; 3. intermediate cylinder; 4. inner cylinder; 5. first annular cavity; 6. second annular cavity; 7. first spiral blade; 8. second spiral blade; 9. end ring plate; 10. first feed port; 11. second feed port; 12. first discharge port; 13. second discharge port; 14. extension cylinder; 15. large pulley; 16. motor; 17. belt; 18. small pulley; 19. rotary joint; 20. filling cylinder; 21. connecting rod; 22. feed hopper; 23. guide hopper; 24. thermal insulation layer. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0021] See also Figure 1-Figure 5The present invention provides a technical solution: a heat exchange device for heating aluminum hydroxide using the waste heat of aluminum oxide, comprising a shell 1, an outer cylinder 2 is rotatably arranged in the shell 1, an intermediate cylinder 3 is fixedly arranged in the outer cylinder 2, an inner cylinder 4 is fixedly arranged in the intermediate cylinder 3, the length of the intermediate cylinder 3 is greater than the length of the outer cylinder 2 and less than the length of the inner cylinder 4, a first annular cavity 5 is formed between the intermediate cylinder 3 and the outer cylinder 2, and the first annular cavity 5 is used to flow aluminum oxide, a second annular cavity 6 is formed between the inner cylinder 4 and the intermediate cylinder 3, and the second annular cavity 6 is used to flow aluminum hydroxide, the intermediate cylinder 3 is a heat-conducting material, and the heat inside the first annular cavity 5 is heated by the heat transfer agent. The aluminum oxide in the first annular cavity 5 is used to heat the aluminum hydroxide in the second annular cavity 6 to achieve heat exchange. A first spiral blade 7 for pushing the internal aluminum oxide to move axially is fixedly arranged in the first annular cavity 5, and a second spiral blade 8 for pushing the internal aluminum hydroxide to move axially is fixedly arranged in the second annular cavity 6. The first spiral blade 7 and the second spiral blade 8 rotate in opposite directions. When the outer cylinder 2, the intermediate cylinder 3, and the inner cylinder 4 rotate at the same time, the materials in the first annular cavity 5 and the second annular cavity 6 can flow in opposite directions, so that the inlet side of the aluminum oxide can be close to the discharge side of the aluminum hydroxide, thereby achieving efficient heat exchange and enabling the discharge side to The temperature of the aluminum hydroxide discharged is higher. End ring plates 9 are fixedly installed at both ends of the outer cylinder 2, the middle cylinder 3, and the inner cylinder 4. The end ring plates 9 are rotated and sealed with the inner wall of the shell 1. A first feed port 10 that can be communicated with the first annular cavity 5 is opened on the upper side of the shell 1. Alumina can enter the first annular cavity 5 through the first feed port 10. A second feed port 11 that can be communicated with the second annular cavity 6 is opened on the other side of the upper side of the shell 1. Aluminum hydroxide can enter the second annular cavity 6 through the second feed port 11. A lower side of the shell 1 is opened that can be communicated with the second annular cavity 6 A second discharge port 13, the aluminum hydroxide in the second annular cavity 6 can be discharged through the second discharge port 13 after being heated, and a first discharge port 12 which can be communicated with the first annular cavity 5 is opened on the other side below the shell 1, and the aluminum oxide in the first annular cavity 5 after heat exchange can be discharged through the first discharge port 12, and both ends of the inner cylinder 4 are fixedly connected with extension cylinders 14, which extend to the outside of the shell 1, and a power source can be connected through the extension cylinder 14 to realize simultaneous rotation of the outer cylinder 2, the middle cylinder 3, and the inner cylinder 4, and the inner wall surface of the shell 1 is coated with a heat insulation layer 24 to improve the thermal insulation effect of the shell 1.

[0022] As an embodiment of the present invention, a motor 16 is fixedly provided on the outer side of the shell 1, a large pulley 15 is fixedly provided on the extension tube 14, a small pulley 18 is fixedly provided on the driving end of the motor 16, and a belt 17 is used to transmit power between the large pulley 15 and the small pulley 18.

[0023] As an embodiment of the present invention, both ends of the shell 1 are fixedly provided with a rotating joint 19 through a mounting frame, the extension tube 14 is connected to the rotating end of the rotating joint 19, a flange is installed at the fixed end of the rotating joint 19, the inner tube 4 is a heat-conducting material, and the air pipe can be connected through the flange of the rotating joint 19, so that high-temperature gas can be passed into the inner tube 4. Through the rotating joint 19, the high-temperature gas can flow into the inner tube 4 while the cylinder body rotates, and the aluminum hydroxide in the second annular cavity 6 is heated or kept warm through the inner tube 4.

[0024] As an embodiment of the present invention, a filling cylinder 20 is fixedly arranged in the inner cylinder 4 through multiple connecting rods 21. The filling cylinder 20 can form a high-temperature gas flow channel in the inner cylinder 4, reduce the flow dead corners of the high-temperature gas, and enable the high-temperature gas to be efficiently utilized.

[0025] As an embodiment of the present invention, the inner tube 4 is filled with insulation material and can seal the extension tube 14. When there is no high-temperature gas available on site, the temperature dissipation and heat dissipation can be reduced by filling the inner tube 4 with insulation material.

[0026] As an embodiment of the present invention, the first feed port 10 and the second feed port 11 are both rectangular openings and are connected to a feed hopper 22 at the top. The upper end of the feed hopper 22 is circular, and the lower end of the feed hopper 22 is a rectangle that can match the feed port. By designing the upper end of the feed hopper 22 to be circular, it is convenient to connect the pipeline. The rectangular feed port can increase the connecting area with the radial direction of the annular cavity, which is convenient for the material to enter the annular cavity. The first discharge port 12 and the second discharge port 13 are both connected to a guide hopper 23 below. The lower outer side of the guide hopper 23 is provided with an opening, and the material is discharged through the opening.

[0027] See also Figure 6 The present invention provides a technical solution: a heat exchange method for a heat exchange device that utilizes waste heat from alumina to heat aluminum hydroxide, wherein a branch pipe is separated from a main pipe connected to the aluminum hydroxide feeding end, the branch pipe is connected to a second feed port 11 in the heat exchange device, and a discharge pipe of a cyclone separator is connected to a first feed port 10 in the heat exchange device.

[0028] As an embodiment of the present invention, a branch pipe is separated from the main pipe connected to the aluminum hydroxide feeding end, the branch pipe is connected to the second feed port 11 in the heat exchange device, the discharge pipe of the cyclone separator is connected to the first feed port 10 in the heat exchange device, and the hot gas discharge end of the cyclone separator is connected to the rotary joint 19 on the heat exchange device using an air pipe.

[0029] As an embodiment of the present invention, the flow rate of aluminum hydroxide in the branch pipe accounts for 1% to 10% of the total output of the aluminum hydroxide feeding end, and the heat exchange time between alumina and aluminum hydroxide in the heat exchange device is 5 minutes to 20 minutes.

[0030] The high temperature resistant material, heat insulating material and heat conducting material are adaptively selected by the skilled person according to the working conditions of each part, and the material properties are well known in the art and will not be further described.

[0031] Through the personnel in this field, all the electrical components in this case are connected to their corresponding power supplies through wires, and a suitable controller should be selected according to the actual situation to meet the control requirements. The specific connection and control sequence should refer to the following working principle, and the electrical connection between the electrical components is completed in the order of working in sequence. The detailed connection means are well-known technologies in this field. The following mainly introduces the working principle and process, and no longer explains the electrical control.

[0032] The working principle and use process of the present invention are as follows: when in use, first start the motor 16 to rotate the outer cylinder 2, the middle cylinder 3, and the inner cylinder 4, and the aluminum oxide can enter the first annular cavity 5 through the first feed port 10. By controlling the flow rate of the aluminum oxide, its height in the first annular cavity 5 can be controlled. In order to facilitate the flow of aluminum oxide, a cavity should be left above the first annular cavity 5 to prevent the aluminum oxide from filling the first annular cavity 5. When the cylinder rotates, the aluminum oxide can be moved toward the first discharge port 12 through the first spiral blade 7. Aluminum hydroxide can enter the second annular cavity 6 through the second feed port 11. By controlling the flow rate of aluminum hydroxide, its height in the second annular cavity 6 can be controlled. In order to facilitate the flow of aluminum hydroxide, a cavity should be left above the second annular cavity 6 to prevent the aluminum oxide from filling the second annular cavity 6. At the same time, the gas discharged by the aluminum hydroxide can be stored in the cavity, and the aluminum hydroxide in the second annular cavity 6 is heated by the aluminum oxide in the first annular cavity 5. To achieve heat exchange, the annular cavity can also increase the heat exchange area of ​​alumina and aluminum hydroxide to ensure sufficient heat exchange between the two. The second spiral blade 8 can move the aluminum hydroxide toward the second discharge port 13, and the first spiral blade 7 and the second spiral blade 8 can make the aluminum oxide and aluminum hydroxide move at a uniform speed in the annular cavity. By changing the rotation speed of the cylinder, the material flow rate can be changed, thereby changing the heat exchange time. The first spiral blade 7 and the second spiral blade 8 rotate in opposite directions to make the materials in the first annular cavity 5 and the second annular cavity 6 flow in opposite directions, so that the inlet side of the aluminum oxide can be close to the discharge side of the aluminum hydroxide, thereby achieving efficient heat exchange. The flange of the rotary joint 19 can be used to connect the air pipe, so that high-temperature gas can be passed into the inner cylinder 4, and the aluminum hydroxide in the second annular cavity 6 can be heated or kept warm by the inner cylinder 4. Finally, the aluminum oxide after heat exchange is discharged through the guide hopper 23 and enters the cooling section.

[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A heat exchange device for heating aluminum hydroxide using the waste heat of aluminum oxide, characterized in that: The invention comprises a shell (1), an outer cylinder (2) is rotatably arranged in the shell (1), an intermediate cylinder (3) is fixedly arranged in the outer cylinder (2), an inner cylinder (4) is fixedly arranged in the intermediate cylinder (3), the length of the intermediate cylinder (3) is greater than the length of the outer cylinder (2) and less than the length of the inner cylinder (4), a first annular cavity (5) is formed between the intermediate cylinder (3) and the outer cylinder (2), a second annular cavity (6) is formed between the inner cylinder (4) and the intermediate cylinder (3), a first spiral blade (7) is fixedly arranged in the first annular cavity (5), a second spiral blade (8) is fixedly arranged in the second annular cavity (6), and the The first spiral blade (7) and the second spiral blade (8) rotate in opposite directions. End ring plates (9) are fixedly installed at both ends of the outer cylinder (2), the intermediate cylinder (3) and the inner cylinder (4). The end ring plates (9) are rotatably and hermetically connected to the inner wall of the shell (1). A first feed port (10) capable of communicating with the first annular cavity (5) is provided on one side above the shell (1). The first feed port (10) is connected to a discharge pipe of a cyclone separator through a pipeline. Aluminum oxide with heat can enter the first annular cavity (5) through the first feed port (10). The other side above the shell (1) A second feed port (11) capable of communicating with the second annular cavity (6) is provided, and the second feed port (11) is connected to the main pipeline of the aluminum hydroxide feeding end through a branch pipe. Unheated aluminum hydroxide can enter the second annular cavity (6) through the second feed port (11), and the aluminum hydroxide in the second annular cavity (6) is heated by the aluminum oxide with heat in the first annular cavity (5). A second discharge port (13) capable of communicating with the second annular cavity (6) is provided on one side below the shell (1), and a first discharge port (12) capable of communicating with the first annular cavity (5) is provided on the other side below the shell (1). Both ends of the inner cylinder (4) are fixedly connected with extension cylinders (14), the extension cylinder (14) extending to the outside of the shell (1), both ends of the shell (1) are fixedly provided with rotating joints (19) through mounting frames, the extension cylinder (14) is connected to the rotating end of the rotating joint (19), the fixed end of the rotating joint (19) is provided with a flange, and the hot air discharged from the cyclone separator can enter the inner cylinder (4) through the rotating joint (19), a filling cylinder (20) is fixedly provided in the inner cylinder (4) through a plurality of connecting rods (21), and the inner wall surface of the shell (1) is coated with a heat insulation layer (24).

2. A heat exchange device for heating aluminum hydroxide using waste heat of aluminum oxide according to claim 1, characterized in that: A motor (16) is fixedly arranged on the outside of the shell (1), a large pulley (15) is fixedly arranged on the extension tube (14), a small pulley (18) is fixedly arranged on the driving end of the motor (16), and a belt (17) is used to drive the large pulley (15) and the small pulley (18).

3. The heat exchange device for heating aluminum hydroxide using waste heat of aluminum oxide according to claim 1, characterized in that: The first feed port (10) and the second feed port (11) are both rectangular openings and are connected to a feed hopper (22) at the top, the upper end of the feed hopper (22) is circular, and the lower end of the feed hopper (22) is rectangular and can match the feed port, and the first discharge port (12) and the second discharge port (13) are both connected to a guide hopper (23) at the bottom, and an opening is provided on the lower outer side of the guide hopper (23).

4. A heat exchange method applied to the heat exchange device for heating aluminum hydroxide using the waste heat of aluminum oxide as claimed in claim 1, characterized in that: A branch pipe is separated from the main pipe connected to the aluminum hydroxide feeding end, and the branch pipe is connected to the second feed port in the heat exchange device. Part of the aluminum hydroxide can be separated from the main pipe connected to the aluminum hydroxide feeding end through the branch pipe, and the unheated aluminum hydroxide can enter the second annular cavity through the second feed port. The discharge pipe of the cyclone separator is connected to the first feed port in the heat exchange device, and the aluminum oxide with heat can enter the first annular cavity through the first feed port. The aluminum hydroxide in the second annular cavity is heated by the heated aluminum oxide in the first annular cavity. The hot gas discharge end of the cyclone separator is connected to the rotary joint at one end of the heat exchange device through an air pipe. The hot gas discharged from the cyclone separator can enter the inner cylinder through the air pipe and the rotary joint to heat the inner cylinder. Finally, the hot gas is discharged through the rotary joint at the other end.

5. The heat exchange method of a heat exchange device for heating aluminum hydroxide using waste heat of aluminum oxide according to claim 4, characterized in that: The flow rate of aluminum hydroxide in the branch pipe accounts for 1% to 10% of the total output of the aluminum hydroxide feeding end, and the heat exchange time between the aluminum oxide and aluminum hydroxide in the heat exchange device is 5 minutes to 20 minutes.

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