Efficient purification absorption tower for fluorine-containing tail gas in wet-process phosphoric acid process

Abstract

The utility model relates to the technical field of phosphoric acid processing equipment, in particular to an efficient purification absorption tower for fluorine-containing tail gas in a wet-process phosphoric acid process, which comprises a tower body, a plurality of baffles and a rotary spray head are mounted in the tower body, and a defluorination tail gas discharge port, a fluorine-containing tail gas connecting pipe, a circulating water connecting pipe and an overflow pipe are arranged on the outer wall of the tower body. The baffles are arranged at different heights in the tower and distributed in a staggered mode. The other rotary spray headers except the rotary spray header at the topmost part are mounted at the lower part; and the defluorination tail gas discharge port is formed in the top of the tower body. According to the efficient purification absorption tower for the fluorine-containing tail gas in the wet-process phosphoric acid process, at least two baffles are arranged in the tower, the retention time of the fluorine-containing tail gas from the tower bottom to the tower top is prolonged, and the absorption efficiency of the absorption tower can be improved. Under the condition of water pressure, the whole rotary spray header can rotate, and spray liquid in all directions of the whole tower and the baffle without dead angles in the rotating process, so that the contact area of the spray liquid and the fluorine-containing tail body is enlarged, and the contact time of the spray liquid and the fluorine-containing tail body is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of phosphoric acid processing equipment, and specifically, to a high-efficiency purification absorption tower for fluorine-containing tail gas in a wet-process phosphoric acid process. Background Art

[0002] Phosphoric acid is a key raw material for preparing products such as new energy batteries, fertilizers, and feeds. Currently, phosphoric acid production processes are mainly divided into two types: wet process and thermal process. Among them, the wet-process phosphoric acid process has become the mainstream phosphoric acid production process in China due to its advantages such as simple operation process and wider applicability. During the production of phosphoric acid by the wet-process phosphoric acid process, the tail gas emitted during reaction processes such as ore decomposition, phosphoric acid concentration, and defluorination process contains a certain amount of fluorine. If the fluorine-containing tail gas is not treated, it will pollute the environment and endanger human health. Moreover, China is rich in fluorite resources, and the fluorite reserves account for 1 / 3 of the world's total reserves, ranking first in the world in terms of fluorite reserves.

[0003] However, fluorite is a non-renewable resource. Currently, China implements a license system for fluorite exports. And with the country's increasing emphasis on environmental protection, the shrinking of fluorine resources, and the expansion of anhydrous hydrogen fluoride production capacity, the efficient recovery and utilization of fluorine resources in wet-process phosphoric acid will become increasingly important. It is necessary to recover all fluorine resources as much as possible to minimize environmental pollution. Treating and absorbing the fluorine-containing tail gas can obtain fluosilicic acid, which can be used to prepare products such as hydrogen fluoride for high-value utilization. Traditional wet-process phosphoric acid tail gas scrubbers all use empty tower spraying, with low tail gas absorption efficiency, incomplete absorption, and certain limitations. Moreover, the wet-process phosphoric acid tail gas scrubbing contains HF and SiF4, and a certain amount of silica gel may form and adhere to the tower interior over a long time. If not treated in time, it will block the pipeline. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a high-efficiency purification absorption tower for fluorine-containing tail gas in a wet-process phosphoric acid process, so as to solve the problems in the above background art that traditional wet-process phosphoric acid tail gas scrubbers all use empty tower spraying, with low tail gas absorption efficiency, incomplete absorption, and certain limitations.

[0005] To achieve the above purpose, the utility model provides a high-efficiency purification absorption tower for fluorine-containing tail gas in a wet-process phosphoric acid process, including a tower body. A number of baffles and rotary spray heads are installed inside the tower body. The outer wall of the tower body is provided with a defluorinated tail gas discharge port, a fluorine-containing tail gas connection pipe, a circulating water connection pipe, and an overflow pipe. The baffles are arranged at different heights in the tower and are staggeredly distributed; except for the rotary spray head at the topmost part, the remaining rotary spray heads are installed below the baffles; the defluorinated tail gas discharge port is arranged at the top of the tower body; the fluorine-containing tail gas connection pipe and the circulating water connection pipe are at the lower part of the tower body, and the fluorine-containing tail gas connection pipe is higher than the liquid level inside the tower body, and a pump is installed on the circulating water connection pipe.

[0006] The baffle is made of 2205 duplex stainless steel, 316 stainless steel or 321 stainless steel, and is in a fan shape with a fan angle of 240°.

[0007] Preferably, there are at least two baffles, and the baffles are arranged staggeredly from top to bottom, so that the vertical channel in the tower is in a serpentine structure, and the ratio of the distance between two plates to the tower diameter is between 1:3 and 1:1.

[0008] Preferably, the topmost rotating spray head is located directly below the defluorinated tail gas discharge port, the bottommost rotating spray head is located directly below the bottommost baffle, and the height of the rotating spray heads other than the topmost and bottommost ones is located in the middle between the upper and lower baffles.

[0009] Preferably, the upper and lower parts of the rotating spray head are hemispheres, and the middle part is a cylinder, and the water pressure of the rotating spray head nozzle is between 0.8 MPa and 2 MPa.

[0010] Preferably, the opening ratio of the opening part of the upper and lower hemispheres is between 30% and 60%, and the ratio of the hole diameter to the cross-sectional diameter of the spray head is between 1:20 and 1:30; the opening ratio of the middle cylinder is between 50% and 70%, and the ratio of the hole diameter to the cross-sectional diameter of the spray head is between 1:10 and 1:20; the included angle between the opening part of the middle cylinder protruding from the surface is between 20° and 60°, and the ratio of the length of the protruding part to the straight cross-section of the spray head is between 1:10 and 1:4, and all the holes are evenly distributed.

[0011] Preferably, the height of the fluorine-containing tail gas connecting pipe is higher than that of the overflow pipe, and the bottom height of the circulating water connecting pipe is lower than that of the overflow pipe.

[0012] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0013] In the high-efficiency purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process, at least two baffles are arranged in the tower, and the baffles are distributed in a staggered manner, so that the residence time of the fluorine-containing tail gas from the bottom of the tower to the top of the tower increases, and the residence time of the spray liquid increases, which can increase the absorption efficiency of the fluorine-containing tail gas.

[0014] Each hole in the middle part of the rotating spray head has a hollow semi-cylindrical protruding surface with a certain angle. Under the condition of water pressure, the entire spray head will rotate, and the upper and lower surfaces of the spray head are hemispheres, which will spray the whole tower and all directions of the baffle without dead angles during the rotation process, improving the contact area and time between the spray liquid and the fluorine-containing tail gas, so as to solve the problems of incomplete absorption and low absorption efficiency of the absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process. And the spray head has a certain water pressure, which can better avoid the agglomeration of the baffle or the silica gel in the tower. Description of the Drawings

[0015] Figure 1 is a schematic diagram of the overall structure of the present utility model;

[0016] Figure 2 is a schematic diagram of the structure of the baffle in the present utility model;

[0017] Figure 3 is a top-down schematic diagram of the top of the rotating spray head in the present utility model;

[0018] Figure 4 is a side schematic diagram of the middle part of the rotating spray head in the present utility model;

[0019] The meanings of each label in the figure are as follows:

[0020] 1. Tower body; 2. Defluorinated tail gas discharge port; 3. Baffle; 4. Rotating spray head; 41. Hemisphere; 42. Cylinder; 5. Fluorine-containing tail gas connecting pipe; 6. Overflow pipe; 7. Circulating water connecting pipe; 8. Pump. Specific embodiments

[0021] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0022] The present utility model provides an efficient purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process, as Figures 1 - 4As shown in the figure, it includes a tower body 1, in which several baffles 3 and rotating spray heads 4 are installed. On the outer wall of the tower body 1, there are a defluorinated tail gas discharge port 2, a fluorine-containing tail gas connecting pipe 5, a circulating water connecting pipe 7, and an overflow pipe 6. The baffles 3 are arranged at different heights in the tower and are staggeredly distributed; except for the rotating spray head 4 at the topmost part, the other rotating spray heads 4 are installed below the baffles 3; the defluorinated tail gas discharge port 2 is arranged at the top of the tower body 1; the fluorine-containing tail gas connecting pipe 5 and the circulating water connecting pipe 7 are at the lower part of the tower body 1, and the fluorine-containing tail gas connecting pipe 5 is higher than the liquid level inside the tower body 1, which can prevent liquid backflow. Through ingenious design, this device can effectively increase the residence time of the fluorine-containing tail gas in the tower, improve the absorption efficiency, and ensure the long-term stable operation of the device. The tower body 1, as the main part of the whole device, provides a space for the fluorine-containing tail gas to contact and react with the absorption liquid. There are at least two baffles 3, which are staggeredly distributed at different heights in the tower. The presence of the baffles increases the residence time of the tail gas, enabling the tail gas to contact and react more fully with the absorption liquid. At the same time, the ratio of the height of the baffle to the tower diameter is between 1:2 and 1:1, providing a suitable position for the installation of the rotating spray head 4. Except for the first rotating spray head 4, the others are installed below the baffle 3. The rotating spray head 4 can rotate under a certain water pressure, thereby increasing the contact area and time between the sprayed liquid and the fluorine-containing tail gas, and improving the absorption efficiency. At the same time, the spray head has a certain water pressure, which helps to avoid caking of the baffle or the silica gel inside the tower. The defluorinated tail gas discharge connection port 2 ensures that the tail gas can pass through the whole tower and makes full use of the effective height of the tower for absorption. The fluorine-containing tail gas connecting pipe 5 and the circulating water connecting pipe 7 are respectively used to connect the fluorine-containing tail gas source and the circulating water source. The fluorine-containing tail gas connecting pipe is higher than the liquid level inside the tower to prevent liquid backflow. A pump 8 is installed on the circulating water connecting pipe 7 for the circulating flow of water.

[0023] In this embodiment, the baffle 3 is made of 2205 duplex stainless steel, 316 stainless steel or 321 stainless steel, and its shape is fan-shaped, with a fan angle of 240°, which ensures the passage of air flow, and the use of stainless steel ensures good corrosion resistance.

[0024] Specifically, there are at least two baffles 3, and the baffles 3 from top to bottom are staggeredly separated, so that the vertical channel inside the tower body 1 is in a serpentine structure, and the distance between the two plates is between 1:3 and 1:1 of the tower diameter, ensuring a certain installation position for the rotating spray head 4.

[0025] Furthermore, the topmost rotating spray head 4 is located directly below the defluorinated tail gas discharge port 2, the bottommost rotating spray head 4 is located directly below the bottommost baffle 3, and the height of the rotating spray heads 4 other than the topmost and bottommost ones is located in the middle between the upper and lower baffles 3.

[0026] Furthermore, the upper and lower parts of the rotary spray head 4 are hemispheres 41, and the middle part is a cylinder 42. The water pressure of the nozzles of the rotary spray head 4 is between 0.8 MPa and 2 MPa.

[0027] Furthermore, the opening ratio of the opening part of the upper and lower hemispheres 41 is between 30% and 60%, and the ratio of the hole diameter to the cross-sectional diameter of the spray head is between 1:20 and 1:30; the opening ratio of the middle cylinder 42 is between 50% and 70%, and the ratio of the hole diameter to the cross-sectional diameter of the spray head is between 1:10 and 1:20; the included angle between the protruding surface of the opening part of the middle cylinder 42 is between 20° and 60°, and the ratio of the length of the protruding part to the straight cross-section of the spray head is between 1:10 and 1:4. All the holes are evenly distributed.

[0028] Furthermore, the height of the fluorine-containing tail gas connecting pipe 5 is higher than that of the overflow pipe 6, and the bottom height of the circulating water connecting pipe 7 is lower than that of the overflow pipe 6.

[0029] When the high-efficiency purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process of the present utility model is in use, first, the fluorine-containing tail gas enters the tower body 1 through the fluorine-containing tail gas connecting pipe 5. Due to the designed height of the fluorine-containing tail gas connecting pipe 5 being higher than the liquid level in the tower, the backflow of liquid is effectively prevented. After entering the tower body, the fluorine-containing gas forms a serpentine flow path under the guidance of the baffle 3 and rises from the bottom of the tower to the top. At least two baffles 3 are provided and are staggered at different heights in the tower. Such a design increases the residence time of the tail gas in the tower, enabling the tail gas to come into contact and react with the absorption liquid more fully.

[0030] Meanwhile, the rotary spray head 4 rotates under a certain water pressure and evenly sprays the absorption liquid into the tower. The ingenious design of the rotary spray head 4, including the upper and lower parts being hemispheres and the middle part being a cylinder, as well as the specific opening ratio and hole diameter ratio, enables the sprayed liquid to cover every position in the entire tower, further increasing the contact area and time between the sprayed liquid and the fluorine-containing tail gas and improving the absorption efficiency. In addition, the water pressure of the spray head helps to avoid caking of the baffle or the silica gel in the tower.

[0031] During the rising process of the fluorine-containing gas, it passes through each position sprayed by the baffle and the rotary spray head, and the fluorine in the gas reacts with the absorption liquid and is gradually absorbed. Finally, the tail gas after sufficient absorption is discharged out of the tower through the defluorinated tail gas discharge connection port 2. Since the residence time of the tail gas in the tower is effectively extended and the contact area between the tail gas and the absorption liquid is fully ensured during the whole process, this device can achieve the high-efficiency purification of fluorine-containing tail gas.

[0032] The foregoing has shown and described the basic principles, main features and advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present utility model and are not used to limit the present utility model. Without departing from the spirit and scope of the present utility model, the present utility model will have various changes and improvements, and these changes and improvements all fall within the scope of the present utility model claimed. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents.

Claims

1. An efficient purification absorption tower for fluorine-containing tail gas in a wet-process phosphoric acid process, comprising a tower body (1), characterized in that: A number of baffles (3) and rotary spray heads (4) are installed inside the tower body (1). The outer wall of the tower body (1) is provided with a defluorination tail gas discharge port (2), a fluorine-containing tail gas connecting pipe (5), a circulating water connecting pipe (7), and an overflow pipe (6). The baffles (3) are arranged at different heights in the tower and are staggeredly distributed; except for the rotary spray head (4) at the topmost part, the remaining rotary spray heads (4) are installed below the baffles (3); the defluorination tail gas discharge port (2) is arranged at the top of the tower body (1); the fluorine-containing tail gas connecting pipe (5) and the circulating water connecting pipe (7) are at the lower part of the tower body (1), and the fluorine-containing tail gas connecting pipe (5) is higher than the liquid level inside the tower body (1), and a pump (8) is installed on the circulating water connecting pipe (7).

2. The high-efficiency purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process according to claim 1, wherein: The baffle (3) is made of stainless steel plate, and its shape is fan-shaped, and the fan angle is 240°.

3. The high-efficiency purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process according to claim 1, wherein: There are at least two baffles (3), and the baffles (3) from top to bottom are staggeredly arranged separately, so that the vertical channel inside the tower body (1) is a serpentine structure, and the ratio of the distance between two plates to the tower diameter is between 1:3 and 1:

1.

4. The high-efficiency purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process according to claim 1, characterized in that: The rotary spray head (4) at the topmost part is located directly below the defluorination tail gas discharge port (2), the rotary spray head (4) at the bottommost part is located directly below the bottommost baffle (3), and the height of the rotary spray heads (4) other than the topmost and bottommost ones is located in the middle between the upper and lower baffles (3).

5. The high-efficiency purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process according to claim 1, characterized in that: The upper and lower parts of the rotary spray head (4) are hemispheres (41), and the middle part is a cylinder (42). The water pressure of the nozzles of the rotary spray head (4) is between 0.8 MPa and 2 MPa.

6. The high-efficiency purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process according to claim 5, characterized in that: The opening ratio of the opening parts of the upper and lower hemispheres (41) is between 30% and 60%, and the ratio of the hole diameter to the cross-sectional diameter of the spray head is between 1:20 and 1:30; the opening ratio of the middle cylinder (42) is between 50% and 70%, and the ratio of the hole diameter to the cross-sectional diameter of the spray head is between 1:10 and 1:20; the included angle of the opening part of the middle cylinder (42) protruding from the surface is between 20° and 60°, and the length of the protruding part to the direct cross-section of the spray head is between 1:10 and 1:4, and all the holes are evenly distributed.

7. The high-efficiency purification absorption tower for fluorine-containing tail gas in the wet-process phosphoric acid process according to claim 1, wherein: The height of the fluorine-containing tail gas connecting pipe (5) is higher than the height of the overflow pipe (6), and the bottom height of the circulating water connecting pipe (7) is lower than the height of the overflow pipe (6).

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