Flue gas recycling device for aluminum hydroxide roasting furnace

Abstract

The utility model discloses a flue gas recycling device for an aluminum hydroxide roasting furnace, which solves the problem of low recycling rate of flue gas waste heat and slag charge of the aluminum hydroxide roasting furnace in the prior art. The dust collection device comprises a collection filter cartridge, a dust collection composite box body and a water heat exchanger, the water outlet end of the water heat exchanger is connected with a spraying mechanism arranged in the collection filter cartridge through a pumping mechanism, and a dust outlet of the collection filter cartridge is communicated to the dust collection composite box body. And a gas outlet of the collection filter cartridge is communicated to the water heat exchanger and the dust collection composite box body. The collecting and filtering cylinder is used for collecting and filtering smoke of the aluminum hydroxide roasting furnace, and the dust collecting composite box body is mainly used for collecting powder slag; the water heat exchanger is mainly used for absorbing waste heat in flue gas, the collection filter cartridge, the dust collection composite box body and the water heat exchanger are matched to complete full recovery and reutilization of useful solids and heat energy in the flue gas of the aluminum hydroxide roasting furnace, and waste of resources and energy is reduced.

Description

Technical Field

[0001] This utility model relates to the field of aluminum hydroxide roasting technology, and in particular to a flue gas recovery and reuse device. Background Technology

[0002] In alumina industrial production, the flue gas temperature from aluminum hydroxide roasting furnaces and sintering kilns reaches as high as 160–190°C. This flue gas not only carries away a large amount of heat, water, and some alumina, but also increases environmental impact. It is estimated that the heat loss from the flue gas from aluminum hydroxide roasting furnaces accounts for 65–70% of the total heat loss in the roasting process. For example, in an alumina plant with an annual production capacity of 1 million tons, the flue gas emission from the aluminum hydroxide roasting furnace is approximately 300,000 Nm³. 3 The flue gas contains approximately 46% water vapor by volume, amounting to about 100 t / h by mass. The latent heat of this water vapor alone exceeds 200 GJ / h. Additionally, the flue gas contains approximately 50 mg / Nm³ of... 3 The annual emission of alumina or aluminum hydroxide dust is approximately 130 tons. Currently, the total production capacity of alumina plants in China exceeds 40 million tons per year, and the flue gas from aluminum hydroxide roasting alone causes huge losses of heat, water, and alumina.

[0003] In the prior art, such as the waste heat recovery device for treating flue gas from an aluminum hydroxide roasting furnace disclosed in CN 113446862 A, the high-temperature flue gas undergoes heat exchange in a heat exchange device, and the water temperature for heat exchange can be 4-5°C higher than the water temperature before heat exchange. Although the above technical solution can save thermal energy during alumina production, the utilization rate of waste heat from the flue gas is not high, and the alumina in the flue gas cannot be fully recovered, which still results in a certain degree of waste of resources and energy. Utility Model Content

[0004] To address the shortcomings in the aforementioned background technology, this utility model proposes a device for recovering and reusing flue gas from an aluminum hydroxide roasting furnace, which solves the problem of low recovery and utilization rates of waste heat and slag from aluminum hydroxide roasting furnace flue gas in the prior art.

[0005] The technical solution of this utility model is implemented as follows: A device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace includes a collection filter cylinder, a dust collection composite box, and a water heat exchanger. The water outlet of the water heat exchanger is connected to a spraying mechanism installed inside the collection filter cylinder via a pumping mechanism. The dust outlet of the collection filter cylinder is connected to the dust collection composite box, and the gas outlet of the collection filter cylinder is connected to the water heat exchanger and the dust collection composite box.

[0006] In a further preferred embodiment, the collecting filter cylinder includes an insulated cylinder body, and a filter screen plate arranged in a spiral shape is provided on the inner wall of the insulated cylinder body. The flue gas is passed into the insulated cylinder body through a first pipe. A spraying mechanism is provided at the top of the insulated cylinder body. A gas outlet is provided at the upper part of the insulated cylinder body. A guide baffle is provided between the gas outlet and the spraying mechanism.

[0007] In a further preferred embodiment, the bottom of the heat insulation cylinder is provided with a first conical hopper, the outlet of which forms a dust outlet for collecting the filter cylinder; the dust outlet is connected to the dust collection composite box through a second pipe.

[0008] More preferably, the spraying mechanism includes a rotating nozzle disposed on the top of the heat insulation cylinder, the water inlet pipe of the rotating nozzle extending upward out of the heat insulation cylinder and connected to the pumping mechanism.

[0009] In a further preferred embodiment, the pumping mechanism includes a pump body disposed outside the water heat exchanger, the inlet of the pump body being connected to the outlet of the water heat exchanger, and the outlet of the pump body being connected to the inlet of the rotating nozzle via a pipe.

[0010] Further preferably, the dust collection composite box includes an outer heat-insulating cylinder and an inner heat-conducting cylinder disposed inside the outer heat-insulating cylinder. A spiral conveying shaft is rotatably disposed inside the inner heat-conducting cylinder. One end of the spiral conveying shaft passes through the inner heat-conducting cylinder and is connected to a motor disposed on the outer heat-insulating cylinder. A discharge pipe is connected to the discharge port of the inner heat-conducting cylinder, and the discharge pipe extends outward through the outer heat-insulating cylinder.

[0011] Further preferably, an annular cavity is provided between the outer heat insulation cylinder and the inner heat-conducting cylinder. The air inlet of the annular cavity is connected to the gas outlet of the collecting filter cylinder through a third pipe. A guide groove is provided at the bottom of the annular cavity, and the guide groove corresponds to the bottom outlet of the annular cavity. A temperature detector for detecting the temperature inside the annular cavity is provided on the outer heat insulation cylinder.

[0012] Further preferably, the water heat exchanger includes a water tank body for holding water, the water tank body is connected to the gas outlet of the collection filter cartridge through a fourth pipe, and the water tank body is equipped with a temperature sensor and a liquid level sensor for displaying the temperature of the water in the water tank body.

[0013] Further preferably, the side wall of the water tank body is provided with a water inlet and a water outlet, and the bottom of the water tank body is provided with a second conical slag discharge hopper, and the bottom of the second conical slag discharge hopper is provided with a slag discharge port and a flushing port.

[0014] The beneficial effects of this utility model are as follows: The collecting filter cylinder of this utility model is used to collect and filter the flue gas from the aluminum hydroxide calcining furnace, realizing the separation of powder slag and high-temperature gas; the dust collecting composite box is mainly used to collect powder slag, so that useful solids such as alumina in the powder slag can be reused; the water heat exchanger is mainly used to absorb the waste heat in the flue gas. The collecting filter cylinder, dust collecting composite box, and water heat exchanger work together to fully recover and reuse useful solids and heat energy in the flue gas of the aluminum hydroxide calcining furnace, reducing the waste of resources and energy. The collecting filter cylinder, dust collecting composite box, and water heat exchanger of this utility model are interconnected to form an internal heat energy circulation system, improving energy utilization efficiency and reducing energy loss.

[0015] This utility model features a spirally arranged filter screen and spray mechanism inside the heat insulation cylinder to improve the recovery efficiency of powder and slag. The dust collection composite box uses an outer heat insulation cylinder and an inner heat-conducting cylinder to dry the slurry inside the inner heat-conducting cylinder, thereby improving the recovery efficiency of the dried powder and slag and facilitating its reuse. This also improves the utilization rate of waste heat from the flue gas and slag in the aluminum hydroxide roasting furnace. Attached Figure Description

[0016] To more clearly illustrate the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0018] Figure 2 This is a schematic diagram of the internal structure of this utility model. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] like Figure 1As shown in Example 1, an aluminum hydroxide calcining furnace flue gas recovery and reuse device includes a collection filter cylinder 1, a dust collection composite box 2, and a water heat exchanger 3. The collection filter cylinder is used to collect and filter the flue gas from the aluminum hydroxide calcining furnace, achieving separation of powder and slag from the gas. The dust collection composite box 2 is mainly used to collect powder and slag, so that useful solids such as alumina in the powder and slag can be reused. The water heat exchanger is mainly used to absorb the waste heat in the flue gas. The collection filter cylinder 1, the dust collection composite box 2, and the water heat exchanger 3 work together to fully recover and reuse useful solids and heat energy in the flue gas from the aluminum hydroxide calcining furnace, reducing the waste of resources and energy. In this embodiment, the water outlet of the water heat exchanger 3 is connected to a spraying mechanism installed in the collection filter cylinder 1 through a pumping mechanism 4. The water medium in the water heat exchanger can be pumped to the spraying mechanism to spray the filter elements in the filter cylinder, reducing dust overflow and preventing dust accumulation on the filter elements, thereby improving the recovery rate of powder and slag. In this embodiment, the dust outlet 1-1 of the collecting filter cartridge 1 is connected to the dust collecting composite box 2 for centralized collection of dust and slag inside the collecting filter cartridge. The gas outlet 1-2 of the collecting filter cartridge 1 is connected to the water heat exchanger 3 and the dust collecting composite box 2; the high-temperature gas inside the collecting filter cartridge 1 enters the water heat exchanger 3, transferring heat energy to the water to heat the water and complete the waste heat recovery and utilization; the high-temperature gas inside the collecting filter cartridge 1 enters the dust collecting composite box 2 to dry the dust and slag inside the dust collecting composite box; the above-mentioned flue gas recovery and reuse device forms a heat energy cycle, improving energy utilization efficiency.

[0021] like Figure 2As shown, the collection filter cylinder 1 in this embodiment includes an insulated cylinder 101, which is made of heat-insulating material to reduce heat loss within the cylinder. The insulated cylinder 101 can be a cylindrical body, and its inner wall is provided with a spirally arranged filter screen 102. The filter screen 102 is inclined towards the bottom, allowing the solid powder portion of the flue gas passing through it to slide down to the first conical hopper 104 at the bottom of the insulated cylinder 101. The powder adhering to the filter screen can be washed away by a spray mechanism and flow into the first conical hopper, improving the recovery efficiency of the powder. In this embodiment, the flue gas is introduced into the insulated cylinder 101 through a first pipe 103. The first pipe can also be an insulated tube, used to transport the flue gas from the aluminum hydroxide roasting furnace to the insulated cylinder 101. The spray mechanism is located at the top inside the insulated cylinder 101, ensuring that the filter screen and the insulated cylinder wall are rinsed. The upper part of the heat-insulating cylinder 101 is provided with a gas outlet 1-2, which is used to discharge the filtered flue gas. To ensure that the filtered flue gas can smoothly enter the gas outlet and to prevent the flue gas from clogging the spray head of the spraying mechanism, a guide baffle 105 is provided between the gas outlet 1-2 and the spraying mechanism. The guide baffle can be inclined towards the gas outlet 1-2, and the guide baffle is provided with screen holes to ensure the normal spraying operation of the spraying mechanism.

[0022] In this embodiment, the bottom of the heat insulation cylinder 101 is provided with a first conical hopper 104. The first conical hopper 104 is provided to facilitate the collection of powder and slag. The outlet of the first conical hopper 104 forms the dust outlet 1-1 of the collection filter cylinder 1. The dust outlet 1-1 is connected to the dust collection composite box 2 through the second pipe 106. The dust and slag in the collection filter cylinder 1 enter the dust collection composite box 2 through the second pipe 106, thus completing the centralized and sustainable collection of dust and slag.

[0023] In this preferred embodiment, the spraying mechanism includes a rotary nozzle 107 mounted on the top of the insulation cylinder 101. The rotary nozzle can be an existing high-temperature resistant rotary nozzle to spray the filter screen and inner wall of the insulation cylinder 101, preventing dust accumulation. It should be noted that this spraying mechanism can be activated periodically. The water inlet pipe of the rotary nozzle 107 extends upwards from the insulation cylinder 101 and is connected to the pumping mechanism. The pumping mechanism 4 includes a pump body 108 disposed outside the water heat exchanger 3. The inlet of the pump body 108 is connected to the outlet of the water heat exchanger 3, and the outlet of the pump body 108 is connected to the inlet of the rotary nozzle 107 via a pipe. The working principle of the pumping mechanism is as follows: when the spraying mechanism needs to work, the pump body is started, and the pump body transports the water in the water heat exchanger to the rotary nozzle through the pipe to spray the filter screen and the inner wall of the heat insulation cylinder. After spraying, the slurry in the heat insulation cylinder enters the dust collection composite box, and after subsequent drying and other processes, the recovery of useful solids is completed.

[0024] Example 2, as Figure 2 As shown, an aluminum hydroxide calcination furnace flue gas recovery and reuse device, based on Example 1, is presented in this preferred embodiment. The dust collection composite box 2 includes an outer heat-insulating cylinder 201 and an inner heat-conducting cylinder 202 disposed within the outer heat-insulating cylinder 201. The outer heat-insulating cylinder 201 is made of heat-insulating material to reduce heat loss entering the outer heat-insulating cylinder 201, while the inner heat-conducting cylinder is made of a heat-conducting material for efficient heat transfer. The high-temperature hot gas entering the outer heat-insulating cylinder dries the slurry inside the inner heat-conducting cylinder, facilitating the recovery of useful solids. A spiral conveying shaft 203 is rotatably mounted inside the inner heat-conducting cylinder 202. The spiral conveying shaft 203 is rotatably mounted within the inner heat-conducting cylinder via bearings along the axial direction of the inner heat-conducting cylinder, and is used for stirring and conveying dust or slag. One end of the screw conveyor shaft 203 passes through the inner heat-conducting cylinder 202 and is connected to the motor 204 mounted on the outer heat-insulating cylinder 201; the motor provides the power for the rotation of the screw conveyor shaft; the discharge port of the inner heat-conducting cylinder 202 is connected to the discharge pipe 205, which extends outward through the outer heat-insulating cylinder 201; the dust or slag inside the inner heat-conducting cylinder is pushed to the discharge port by the screw conveyor shaft and discharged out of the cylinder through the discharge pipe for subsequent continuous collection and utilization.

[0025] In this preferred embodiment, an annular cavity 207 is provided between the outer heat-insulating cylinder 201 and the inner heat-conducting cylinder 202. High-temperature flue gas from the collection filter cylinder enters the annular cavity, forming an annular wrap around the inner heat-conducting cylinder, thus improving drying efficiency. The air inlet of the annular cavity 207 is connected to the gas outlet 1-2 of the collection filter cylinder 1 via a third pipe 206, enabling flue gas flow from the collection filter cylinder to the annular cavity. A guide groove 208 is provided at the bottom of the annular cavity 207, corresponding to the bottom outlet 209 of the annular cavity 207. Moisture carried by the flue gas entering the annular cavity will partially condense and liquefy upon encountering the inner heat-conducting cylinder. This moisture can then flow through the guide groove to the bottom outlet and exit, completing the partial recovery of moisture from the flue gas. To facilitate observation and detection of the temperature inside the annular cavity, a temperature detector 210 for detecting the temperature inside the annular cavity 207 is provided on the outer heat insulation cylinder 201; later, a flow valve can be installed on the third pipe to control the stability inside the annular cavity and realize the full utilization of the heat energy of the flue gas during the drying process.

[0026] In this preferred embodiment, the water heat exchanger 3 includes a water tank body 301 for holding water. The water tank body 301 is connected to the gas outlet 1-2 of the collection filter cylinder 1 via a fourth pipe 302. The high-temperature flue gas in the collection filter cylinder 1 directly enters the water tank body through the fourth pipe, where it contacts and exchanges heat with the water medium inside the water tank body, thus heating the water in the tank. To detect the stability and level of the water in the tank, the water tank body 301 is equipped with a temperature sensor and a level sensor. The heated water can be pumped back into the collection filter cylinder 1 for spray cleaning and dust reduction, and can also be connected to an external hot water device to fully utilize and circulate the waste heat of the flue gas. Preferably, in this embodiment, the side wall of the water tank body 301 is provided with an inlet 303 and an outlet 304 for water intake and drainage. The bottom of the water tank body 301 is provided with a second conical slag hopper 305 for secondary collection of slag. The bottom of the second conical slag hopper 305 is provided with a slag outlet and a flushing outlet. Dust or slag carried in the flue gas will be deposited at the second conical slag outlet during the heat exchange process, and then discharged through the slag outlet, thus completing the further collection of dust or slag in the flue gas; the flushing port is designed to flush the second conical slag outlet and prevent blockage.

[0027] The specific usage process is as follows: The flue gas in the aluminum hydroxide calcining furnace enters the insulated cylinder 101 and is filtered inside the insulated cylinder 101. The dust or slag in the flue gas enters the first conical hopper 104 and then enters the inner heat-conducting cylinder 202 of the dust collection composite box 2. Under the action of its spiral conveying shaft, the dust or slag is collected. The high-temperature gas containing a small amount of slag in the flue gas can be selectively introduced into the water heat exchanger 3 and / or the dust collection composite box. When entering the water heat exchanger, the water in the water tank is heated. When entering the outer insulated cylinder 201 of the dust collection composite box, the inner heat-conducting cylinder 202 is dried. The high-temperature gas containing a small amount of slag entering the water tank forms a deposit in the second conical slag discharge hopper at the bottom of the water tank body 301. It can be discharged through the slag discharge port later, completing the further collection of dust or slag in the flue gas.

[0028] When dust accumulates on the filter screen and inner wall of the insulation cylinder 101, the pumping mechanism is activated to pump water from the water heat exchanger 3 to the spraying mechanism to spray the filter screen and inner wall of the insulation cylinder 101. The resulting slurry enters the inner heat-conducting cylinder 202 of the dust collection composite box 2. At this time, the high-temperature gas containing a small amount of slag dries the slurry in the inner heat-conducting cylinder 202. Then, under the action of the screw conveyor shaft, the dust or slag is collected.

[0029] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace, characterized in that: It includes a collection filter cartridge (1), a dust collection composite box (2) and a water heat exchanger (3). The water outlet of the water heat exchanger (3) is connected to a spraying mechanism set inside the collection filter cartridge (1) via a pumping mechanism (4). The dust outlet (1-1) of the collection filter cartridge (1) is connected to the dust collection composite box (2), and the gas outlet (1-2) of the collection filter cartridge (1) is connected to the water heat exchanger (3) and the dust collection composite box (2).

2. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 1, characterized in that: The collection filter cylinder (1) includes an insulated cylinder (101), and a filter screen (102) arranged in a spiral shape is provided on the inner wall of the insulated cylinder (101). The flue gas is passed into the insulated cylinder (101) through the first pipe (103). The spraying mechanism is located at the top of the insulated cylinder (101). The upper part of the insulated cylinder (101) is provided with a gas outlet (1-2), and a guide baffle (105) is provided between the gas outlet (1-2) and the spraying mechanism.

3. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 2, characterized in that: The bottom of the heat insulation cylinder (101) is provided with a first conical hopper (104), and the outlet of the first conical hopper (104) forms the dust outlet (1-1) of the collection filter cylinder (1); the dust outlet (1-1) is connected to the dust collection composite box (2) through the second pipe (106).

4. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 2 or 3, characterized in that: The spraying mechanism includes a rotating nozzle (107) located on the top of the heat insulation cylinder (101). The water inlet pipe of the rotating nozzle (107) extends upward from the heat insulation cylinder (101) and is connected to the pumping mechanism.

5. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 4, characterized in that: The pumping mechanism includes a pump body (108) located outside the water heat exchanger (3). The inlet of the pump body (108) is connected to the outlet of the water heat exchanger (3), and the outlet of the pump body (108) is connected to the inlet of the rotary nozzle (107) via a pipe.

6. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 1 or 5, characterized in that: The dust collection composite box (2) includes an outer heat-insulating cylinder (201) and an inner heat-conducting cylinder (202) disposed inside the outer heat-insulating cylinder (201). A spiral conveying shaft (203) is rotatably disposed inside the inner heat-conducting cylinder (202). One end of the spiral conveying shaft (203) passes through the inner heat-conducting cylinder (202) and is connected to a motor (204) disposed on the outer heat-insulating cylinder (201). A discharge pipe (205) is connected to the discharge port of the inner heat-conducting cylinder (202). The discharge pipe (205) extends outward through the outer heat-insulating cylinder (201).

7. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 6, characterized in that: An annular cavity (207) is provided between the outer heat insulation cylinder (201) and the inner heat conduction cylinder (202). The air inlet of the annular cavity (207) is connected to the gas outlet (1-2) of the collection filter cylinder (1) through the third pipe (206). A guide groove (208) is provided at the bottom of the annular cavity (207), and the guide groove (208) corresponds to the bottom outlet (209) of the annular cavity (207).

8. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 7, characterized in that: The outer heat insulation cylinder (201) is equipped with a temperature detector (210) for detecting the temperature inside the annular cavity (207).

9. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 1, 7, or 8, characterized in that: The water heat exchanger (3) includes a water tank body (301) for holding water. The water tank body (301) is connected to the gas outlet (1-2) of the collection filter cylinder (1) through a fourth pipe (302). The water tank body (301) is equipped with a temperature sensor and a liquid level sensor.

10. The device for recovering and reusing flue gas from an aluminum hydroxide calcining furnace according to claim 9, characterized in that: The water tank body (301) has an inlet (303) and an outlet (304) on its side wall. The bottom of the water tank body (301) has a second conical slag hopper (305). The bottom of the second conical slag hopper (305) has a slag outlet and a flushing outlet.

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