An air locking and ash discharging device for an alumina calcination furnace flue gas heat exchanger

Abstract

This invention relates to an airlock ash removal device for a flue gas heat exchanger in an alumina calcining furnace. A diversion valve is installed at the bottom of the main ash removal pipe, with two discharge ports. Each discharge port is equipped with a branch ash removal pipe. The ash removal device also includes a first main water seal chamber, a second main water seal chamber, and an auxiliary water seal chamber. The bottom of each branch ash removal pipe passes through the top of its corresponding main water seal chamber and inserts into the water seal liquid within that chamber. The auxiliary water seal chamber contains a first auxiliary water seal pipe and a second auxiliary water seal pipe. The auxiliary water seal pipe includes a vertical section and a horizontal section connected to the upper end of the vertical section and communicating with the inner cavity of the corresponding main water seal chamber. The bottom of the vertical section extends into the water seal liquid in the auxiliary water seal chamber, and the height of the horizontal section is higher than the water seal liquid levels in both the auxiliary and main water seal chambers. Both the first and second main water seal chambers are equipped with drain ports. This invention solves the technical problem in the prior art where accumulated ash and water droplets at the heat exchanger easily cause blockage of the ash removal pipe.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery and utilization of flue gas in the alumina production process, and particularly to a lock-air ash removal device for a flue gas heat exchanger in an alumina calcining furnace. Background Technology

[0002] Currently, in the production process of alumina, calcination is the last step. The main task of this process is to calcine aluminum hydroxide with attached water and crystal water at high temperature in a calcination furnace to remove the attached water and crystal water, thereby producing an alumina product with the required physicochemical properties.

[0003] In actual production, the flue gas from the aluminum hydroxide roasting furnace is discharged by a fan at a temperature of around 160°C, resulting in a waste of energy resources and environmental pollution.

[0004] Currently, most alumina plants utilize indirect heat exchange equipment, such as flue gas heat exchangers, to recover waste heat from the calcination flue gas. After heat recovery, the flue gas temperature drops to around 110℃ before being discharged through the chimney. The calcination furnace flue gas has a high moisture content (approximately 40%), so the flue gas heat exchanger is located after the dust removal equipment. Currently, the dust content in the flue gas emitted by alumina plants is generally controlled at 5 mg / Nm³. 3 To ensure that there is no ash accumulation on the inner surface of the heat exchanger, a soot blowing device is usually installed on the flue gas heat exchanger. The blown-off ash is collected through the ash hopper at the bottom of the heat exchanger and discharged to the ground through the ash discharge pipe. The ash discharge pipe is equipped with an ash discharge valve, which serves to lock the air and discharge ash.

[0005] The problem with the existing technology is that the flue gas in the roasting furnace has a high moisture content (about 40%). In areas with low winter temperatures, the moisture in the flue gas is easy to condense into water. Water droplets and ash accumulation can easily cause blockage of the ash discharge pipe and improper closure of the ash discharge valve. Blockage of the ash discharge pipe will increase the workload of equipment maintenance, and improper closure of the ash discharge valve will lead to an increase in the air leakage coefficient of the equipment, increase the operating power of the fan, and cause energy waste. Summary of the Invention

[0006] The purpose of this invention is to provide an airlock ash removal device for the flue gas heat exchanger of an alumina calcining furnace, in order to solve the technical problem in the prior art where the combination of ash accumulation and water droplets at the heat exchanger easily causes blockage of the ash removal pipe.

[0007] The technical solution of the airlock ash removal device for the flue gas heat exchanger of an alumina calcining furnace in this invention is as follows:

[0008] A flue gas heat exchanger ash removal device for an alumina calcining furnace includes a flue gas heat exchanger with an air inlet at the front and an air outlet at the rear. An ash hopper is located at the bottom of the heat exchanger. Heat exchange tubes for heat exchange with the flue gas are installed inside the heat exchanger. A main ash removal pipe is connected to the bottom of the ash hopper. A diversion valve is located at the bottom of the main ash removal pipe, and the diversion valve has two discharge ports. Each discharge port is connected to a branch ash removal pipe. The ash removal device also includes a first main water seal chamber, a second main water seal chamber, and an auxiliary water seal chamber. The inner cavity of each main water seal chamber is used to fill with water seal fluid. The inner cavity of the water seal chamber is used to fill the auxiliary water seal chamber with water seal fluid. The bottom of each branch ash discharge pipe passes through the top of the corresponding main water seal chamber and is inserted into the corresponding main water seal chamber water seal fluid. The auxiliary water seal chamber is equipped with a first auxiliary water seal pipe and a second auxiliary water seal pipe. The auxiliary water seal pipe includes a vertical section and a horizontal section connected to the upper end of the vertical section and communicating with the inner cavity of the corresponding main water seal chamber. The bottom of the vertical section extends into the auxiliary water seal chamber water seal fluid, and the height of the horizontal section is higher than the liquid level of the auxiliary water seal chamber water seal fluid and the liquid level of the main water seal chamber water seal fluid. Both the first main water seal chamber and the second main water seal chamber are equipped with a drain outlet.

[0009] Furthermore, the ash removal device includes a dust removal water tank, which includes a top plate, a bottom plate, and a side plate connected between the top plate and the bottom plate. The tank cavity is divided into a left chamber and a right chamber by a longitudinal partition. The left chamber constitutes the auxiliary water seal chamber, and the right chamber is divided into a front chamber and a rear chamber by a transverse partition. The front chamber constitutes the first main water seal chamber, and the rear chamber constitutes the second main water seal chamber.

[0010] Furthermore, the first auxiliary water seal pipe and the second auxiliary water seal pipe are spaced apart, and the transverse sections of each auxiliary water seal pipe are fixedly connected to the front and rear ends of the longitudinal partition.

[0011] Furthermore, a water inlet is provided on the top plate of the water tank corresponding to the auxiliary water seal chamber.

[0012] Furthermore, an overflow port and a level gauge are provided on the side plate of the water tank corresponding to the auxiliary water seal chamber.

[0013] The beneficial effects of this application are as follows: In this invention, the two branch ash discharge pipes are referred to as the first branch ash discharge pipe and the second branch ash discharge pipe, respectively. The diversion valve can adjust the dust ratio of the first branch ash discharge pipe and the second branch ash discharge pipe, and can also realize the closure of the first branch ash discharge pipe and opening of the second branch ash discharge pipe, and the closure of the second branch ash discharge pipe and opening of the first branch ash discharge pipe. When efficient ash removal is required, the ash falling ratio of the first branch ash discharge pipe and the second branch ash discharge pipe can be 1:1. The dust falls into the first main water seal chamber and the second main water seal chamber respectively, and efficient ash removal is carried out simultaneously in the two main seal chambers. At the same time, since the flue gas heat exchanger is in a negative pressure environment, the water in the corresponding main water seal chamber will be drawn into the corresponding branch ash discharge pipe to form a water column. The negative pressure environment of the main water seal chamber also causes the vertical section of the auxiliary water seal pipe to draw water from the auxiliary water seal chamber to form a water column. This effectively reduces the height of the water column, thereby effectively reducing the required length of the main ash discharge pipe, which can be adapted to the use conditions when the ash hopper is in a low position. When one of the main water seal chambers needs to be cleaned, the corresponding branch ash discharge pipe is closed, and the drain port on the main water seal chamber is opened for sludge discharge. The other main water seal chamber can continue to work, and there will be no problem of dust not being handled due to the cleaning of the main water seal chamber. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of the coordination between the main water seal chamber and the auxiliary water seal chamber from a top-down perspective;

[0016] Figure 3 This is a schematic diagram showing the connection between the branch ash discharge pipe and the main water seal chamber from a side view.

[0017] In the diagram: 1. Flue gas heat exchanger; 2. Ash hopper; 3. Main ash discharge pipe; 4. Diversion valve; 5. Branch ash discharge pipe; 6. Water column; 7. Water tank top plate; 8. Water tank side plate; 9. Drain outlet; 10. Water tank bottom plate; 11. Longitudinal partition; 12. Vertical section; 13. Horizontal section; 14. First auxiliary water seal pipe; 15. Water inlet; 16. Overflow outlet; 17. Level gauge; 18. Dust removal water tank; 19. Horizontal partition; 20. Second auxiliary water seal pipe; 21. Auxiliary water seal chamber; 22. First main water seal chamber; 23. Second main water seal chamber; 24. Air inlet; 25. Air outlet. Detailed Implementation

[0018] 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 only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0021] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0022] A specific embodiment of the airlock ash removal device for the flue gas heat exchanger of an alumina calcining furnace in this invention is as follows: Figures 1-3 As shown,

[0023] It includes a flue gas heat exchanger 1 with an air inlet 24 at the front end and an air outlet 25 at the rear end. The flue gas heat exchanger 1 is equipped with heat exchange tubes for exchanging heat with the flue gas. When in use, the cooling medium (water) flows through the heat exchange tubes and exchanges heat with the flue gas through the tube walls.

[0024] The bottom of the flue gas heat exchanger 1 is equipped with an ash hopper 2, and the bottom of the ash hopper 2 is connected to the main ash discharge pipe 3. All of the above are existing technologies and will not be described in detail here.

[0025] The dust removal device in this invention also includes a dust removal water tank 18. The dust removal water tank 18 includes a water tank top plate 7, a water tank bottom plate 10, and a water tank side plate 8 connected between the water tank top plate 7 and the water tank bottom plate 10. The tank cavity of the dust removal water tank 18 is divided into a left side chamber and a right side chamber by a longitudinal partition 11. The left side chamber constitutes an auxiliary water seal chamber 21. The right side chamber is divided into a front side chamber and a rear side chamber by a transverse partition 19. The front side chamber constitutes a first main water seal chamber 22, and the rear side chamber constitutes a second main water seal chamber 23.

[0026] When in use, water needs to be filled into the auxiliary water seal chamber 21 and the main water seal chamber.

[0027] The auxiliary water seal chamber 21 is provided with a first auxiliary water seal pipe 14 and a second auxiliary water seal pipe 20 arranged at intervals. The first auxiliary water seal pipe 14 and the second auxiliary water seal pipe 20 have the same structure. The auxiliary water seal pipe includes a vertical section 12 and a transverse section 13 connected to the upper end of the vertical section 12 and communicating with the corresponding main water seal chamber cavity. The bottom of the vertical section 12 extends into the water seal fluid of the auxiliary water seal chamber 21, and the height of the transverse section 13 is higher than the liquid level of the water seal fluid in the auxiliary water seal chamber 21 and the liquid level of the water seal fluid in the main water seal chamber. In this embodiment, the transverse section 13 of each auxiliary water seal pipe is fixedly connected to the front and rear ends of the longitudinal partition 11. The transverse section 13 of the first auxiliary water seal pipe 14 is connected to the first main water seal chamber 22, and the transverse section 13 of the second auxiliary water seal pipe 20 is connected to the second main water seal chamber 23.

[0028] A water inlet 15 is provided on the top plate 7 of the water tank corresponding to the auxiliary water seal chamber 21, and an overflow port 16 and a level gauge 17 are provided on the side plate 8 of the water tank corresponding to the auxiliary water seal chamber 21.

[0029] In this embodiment, a diversion valve 4 is provided at the bottom of the main ash discharge pipe 3. The diversion valve 4 has two discharge ports, and each discharge port is provided with a branch ash discharge pipe 5. The bottom of each branch ash discharge pipe 5 passes through the top plate 7 of the water tank of the corresponding main water seal chamber and is inserted into the water seal liquid of the corresponding main water seal chamber to form a water column 6.

[0030] The two branch ash discharge pipes 5 are respectively referred to as the first branch ash discharge pipe 5 connected to the first main water seal chamber 22 and the second branch ash discharge pipe 5 connected to the second main water seal chamber 23. In this embodiment, the diversion valve 4 is a flap-type reversing valve, which can achieve the following functions: 1. Close the first branch ash discharge pipe 5 and open the second branch ash discharge pipe 5; 2. Close the second branch ash discharge pipe 5 and open the first branch ash discharge pipe 5; 3. Adjust the dust flow rate to the first branch ash discharge pipe 5 and the second branch ash discharge pipe 5 in any proportion. The diversion valve 4 is prior art, and its specific structure will not be described in detail here.

[0031] In this invention, the opening ratio of the diversion valve 4 is adjusted according to the water volume of the first main water seal chamber 22 and the second main water seal chamber 23 (the water volume determines the dust removal capacity). For example, in this embodiment, the water volume of the first main water seal chamber 22 and the second main water seal chamber 23 is the same, so the valve plate of the diversion valve 4 can be adjusted to the middle position, and the dust flow ratio diverted from the main ash discharge pipe 3 by the first ash discharge pipe 5 and the second ash discharge pipe 5 is 1:1. In other embodiments of this invention, when the water volume ratio of the first main water seal chamber and the second main water seal chamber 23 is 6:4, the valve plate of the diversion valve 4 can be adjusted so that the dust flow ratio diverted from the main ash discharge pipe 3 by the first ash discharge pipe 5 and the second ash discharge pipe 5 is 6:4, thereby enabling the first main water seal chamber 22 and the second main water seal chamber 23 to work simultaneously and remove dust efficiently.

[0032] Each main water seal chamber is also equipped with a water inlet.

[0033] When a main water seal chamber needs cleaning, the ash inlet of its corresponding branch ash discharge pipe 5 is closed. At this time, the other main water seal chamber continues to operate to ensure continuous ash removal. After the main water seal chamber is cleaned through the drain port 9, it is refilled with water, and the corresponding branch ash discharge pipe 5 is reopened to continue operation, ensuring the continuity of ash removal. In addition, since the flue gas heat exchanger 1 is connected upstream of the fan, the flue gas heat exchanger 1 is in a negative pressure environment. The water in the corresponding main water seal chamber is drawn into the corresponding branch ash discharge pipe 5 to form a water column 6. The negative pressure environment of the main water seal chamber also causes the vertical section 12 in the auxiliary water seal pipe to draw water from the auxiliary water seal chamber 21 to form a water column 6, effectively reducing the height of the water column 6, thereby effectively reducing the required length of the main ash discharge pipe 3, which can adapt to the operating conditions when the ash hopper 2 is in a low position.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A flue gas heat exchanger with airlock and ash removal device for an alumina calcining furnace, comprising a flue gas heat exchanger having an air inlet at the front end and an air outlet at the rear end, an ash hopper at the bottom of the flue gas heat exchanger, heat exchange tubes for exchanging heat with the flue gas inside the flue gas heat exchanger, and a main ash removal pipe connected to the bottom of the ash hopper, characterized in that: A diversion valve is installed at the bottom of the main ash discharge pipe. The diversion valve has two discharge ports, and each discharge port is equipped with a branch ash discharge pipe. The ash discharge device also includes a first main water seal chamber, a second main water seal chamber, and an auxiliary water seal chamber. The inner cavity of each main water seal chamber is used to fill the main water seal chamber water seal fluid, and the inner cavity of the auxiliary water seal chamber is used to fill the auxiliary water seal chamber water seal fluid. The bottom of each branch ash discharge pipe passes through the top of the corresponding main water seal chamber and is inserted into the corresponding main water seal chamber water seal fluid. The auxiliary water seal chamber is equipped with a first auxiliary water seal pipe and a second auxiliary water seal pipe. The auxiliary water seal pipe includes a vertical section and a horizontal section connected to the upper end of the vertical section and communicating with the inner cavity of the corresponding main water seal chamber. The bottom of the vertical section extends into the auxiliary water seal chamber water seal fluid, and the height of the horizontal section is higher than the liquid level of the auxiliary water seal chamber water seal fluid and the liquid level of the main water seal chamber water seal fluid. Both the first and second main water seal chambers are equipped with drain ports.

2. The airlock ash removal device for the flue gas heat exchanger of the alumina calcining furnace according to claim 1, characterized in that: The ash removal device includes a dust removal water tank, which includes a top plate, a bottom plate, and a side plate connected between the top plate and the bottom plate. The tank cavity is divided into a left chamber and a right chamber by a longitudinal partition. The left chamber constitutes the auxiliary water seal chamber, and the right chamber is divided into a front chamber and a rear chamber by a transverse partition. The front chamber constitutes the first main water seal chamber, and the rear chamber constitutes the second main water seal chamber.

3. The airlock ash removal device for the flue gas heat exchanger of the alumina calcining furnace according to claim 2, characterized in that: The first and second auxiliary water seal pipes are spaced apart, with the transverse sections of each auxiliary water seal pipe fixedly connected to the front and rear ends of the longitudinal partition.

4. The airlock ash removal device for the flue gas heat exchanger of the alumina calcining furnace according to claim 2, characterized in that: A water inlet is provided on the top plate of the water tank corresponding to the auxiliary water seal chamber.

5. The airlock ash removal device for the flue gas heat exchanger of the alumina calcining furnace according to claim 2, characterized in that: An overflow port and a level gauge are installed on the side plate of the water tank corresponding to the auxiliary water seal chamber.

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