Tail gas washing and separating device of wet-process phosphoric acid extraction tank

Abstract

The utility model belongs to the technical field of wet-process phosphoric acid extraction tank tail gas treatment, and particularly relates to a wet-process phosphoric acid extraction tank tail gas washing and separating device which comprises an extraction tank, a pipeline washer, a first washing tower and a tail gas fan, the upper end of the extraction tank is connected with a gas inlet of the pipeline washer, and the bottom side of the pipeline washer is connected with the first washing tower; the bottom end of the pipeline washer is connected with the first sedimentation pipe; the upper end of the first washing tower is connected with a tail gas fan through a tail gas pipeline; the bottom end of the tail gas pipeline is connected with a second settling pipe; and the first settling pipe, the second settling pipe and the first washing tower are respectively connected with the slag discharge pump through pipelines. The device is simple and novel in design, low in investment cost, capable of effectively separating and removing silica gel and other solid-phase substances separated out in the washing process of extraction tail gas, easy and convenient to maintain and capable of prolonging the operation cycle of the device.

Description

Technical Field

[0001] The utility model belongs to the technical field of tail gas treatment in a wet process phosphoric acid extraction tank, in particular to a tail gas washing and separation device in a wet process phosphoric acid extraction tank. Background Art

[0002] At present, large-scale wet phosphoric acid plants generally have problems such as short operation cycle of the exhaust fan of the extraction tank: 3-5 days, frequent shutdown for cleaning of the fan impeller, and maintenance. The main manifestations are fan vibration. In severe vibration, the vibration speed reaches 50mm / s, fan bearing damage, anchor bolts break, impeller lining rubber (vulcanized rubber) burst, impeller loosening and shaft head corrosion, and the fan casing and impeller are full of silica gel. The reason for analysis is that silica gel is enriched on the fan impeller, and the impeller imbalance causes fan vibration.

[0003] In order to solve the problem, from the perspective of equipment management, the fan impellers are frequently replaced, and great efforts are made in fan maintenance, inspection, and especially overall leveling and alignment, and the fan feet are reinforced; secondly, inspection and flushing holes and sewage outlets are opened on the casing, and it is stipulated that the fan impellers must be flushed regularly at the beginning of each shift, and the gas phase cross pipe must be flushed regularly every week; thirdly, impeller flushing water pipes are added to the casing. More and more flushing water pipes are added. Although continuous flushing of the impeller is achieved, the operating cycle is still only 5-7 days, which does not fundamentally solve the problem. Instead, it causes leakage of thin materials in the casing shaft hole, inspection hole and other parts, resulting in on-site environmental problems.

[0004] After the exhaust fan of the extraction tank was shut down, all areas of the extraction tank were seriously smoked, and choking fluorine- and sulfur-containing gases filled the device. The extraction tank was forced to stop adding materials or reduce load production, seriously affecting the production capacity of the device; in addition, the gas phase cross pipe and the Venturi spray device were particularly seriously hung with materials, the pipe wall was easily scaled, and the nozzle of the first washing tower was seriously blocked, which led to the blockage of the spray pipe. The continuous operation time of the extraction tank exhaust gas washing device was only about 30 days. The gas phase cross pipe had to be flushed and cleaned every week, and the entire exhaust gas washing system had to be stopped and cleaned once a month.

[0005] like Figure 1 As shown, it is a process flow chart of tail gas treatment of wet phosphoric acid extraction tank in the prior art. The fluorine-containing gas from the extraction tank 1 enters the venturi scrubber 2 for washing and then enters the first tail gas washing tower 3. The tail gas washed by the nozzle 31 of the first tail gas washing tower 3 is sucked by the fan 5 and sent to the second tail gas washing tower. The manifestation is that the silica gel of the extraction tail washing is seriously moved backward. The fundamental problem is still in the venturi scrubber 2 and the first washing tower 3, that is, the silica gel that should be washed and separated in the venturi scrubber 2 and the first washing tower 3 moves backward with the tail gas to the tail gas fan 5, and the tail gas fan 5 that sucks gas becomes a gas-gel mixture, which then causes problems with the tail gas fan 5.

[0006] (1) Since the top gas phase horizontal pipe of the venturi scrubber 2 is provided with a top spray 21, the sulfur-containing and fluorine-containing gas at about 85°C sucked out from the extraction tank 1 contacts with the washing water at about 30°C when it comes out of the extraction tank 1, and the temperature drops rapidly, and a large amount of silica gel is rapidly precipitated, blocking the gas phase horizontal pipe and the top spray 21;

[0007] (2) The gas phase horizontal pipe is arranged horizontally, which easily leads to scaling, and there is water accumulation at the bottom of the pipe, which further aggravates the precipitation of silica gel on the wall after contact with fluorine-containing gas at about 85°C;

[0008] (3) The Venturi scrubber 2 is arranged between the first scrubbing tower 3 and the extraction tank 1. The gas temperature is relatively high, and it is easy to form crystalline substances attached to the inner wall of the pipeline and the spray device. During the scrubbing process, the high-temperature gas flowing at a high speed and the scrubbing liquid are rapidly cooled when mixed, which aggravates the crystallization of silica gel, the Venturi spray device is hung with materials, the pipeline wall is easily scaled, and the gas channel is blocked, which affects the scrubbing efficiency and causes the silica gel to move to the first scrubbing tower 3;

[0009] (4) The solid phase washed by the venturi scrubber 2, including the washing water, enters the first washing tower 3 along with the gas, and the gas-liquid and gas-solid separation is achieved in the first washing tower 3. The solid phase and condensate entrained by the gas at the top outlet of the first washing tower 3 directly enter the exhaust fan 5 through the exhaust pipe 4;

[0010] (5) The solid phase washed by the Venturi scrubber 2, including the washing water, enters the first washing tower 3 in large quantities along with the gas. The washing liquid stays in the tower for too long, which aggravates the crystallization of silica gel and other substances. After the crystallized substances enter the spray system, they further clog the nozzles and spray pipes, eventually causing the entire spray system to be clogged, forming a vicious cycle. Utility Model Content

[0011] In view of the technical problems existing in the background technology, the utility model provides a tail gas washing and separation device for a wet phosphoric acid extraction tank.

[0012] In order to achieve the above purpose, the technical solution provided by the utility model is:

[0013] A tail gas washing and separation device for a wet phosphoric acid extraction tank comprises an extraction tank, a pipeline scrubber, a first washing tower and a tail gas fan, wherein the upper end of the extraction tank is connected to an air inlet of the pipeline scrubber, the air outlet on the bottom side of the pipeline scrubber is connected to the first washing tower, and the bottom end of the pipeline scrubber is connected to a first settling pipe; the upper end of the first washing tower is connected to the tail gas fan through a tail gas pipeline, and the bottom end of the tail gas pipeline is connected to a second settling pipe; the first settling pipe, the second settling pipe and the bottom end of the first washing tower are respectively connected to a slag discharge pump through pipelines, and solid slag is discharged into a slag discharge tank through the slag discharge pump.

[0014] Optionally, the pipeline scrubber includes a gas phase horizontal pipe and a washing vertical pipe, the gas phase horizontal pipe is arranged at the upper end of the extraction tank, and the gas phase horizontal pipe extends downwardly at an angle toward the washing vertical pipe, the air inlet of the gas phase horizontal pipe is connected to the extraction tank, and the bottom end of the washing vertical pipe is connected to the first sedimentation pipe.

[0015] Optionally, one end of the gas phase horizontal pipe is connected to a curved pipe, the bottom end of the curved pipe is connected to a washing vertical pipe, a vertically arranged first nozzle is arranged at the top of the curved pipe, the first nozzle extends into the curved pipe, a first nozzle is connected to the end of the first nozzle, and the first nozzle is used to spray the curved inner wall of the curved pipe.

[0016] Optionally, the vertical washing pipe is provided with a plurality of second spray pipes arranged transversely along the height direction, the second spray pipes extend into the vertical washing pipe, and the ends of the second spray pipes are connected with second spray heads.

[0017] Optionally, the angle between the gas phase horizontal tube and the horizontal plane is 5°.

[0018] Optionally, the first washing tower is provided with a plurality of transversely arranged third nozzles along the height direction, the third nozzles extend into the first washing tower, the ends of the third nozzles are connected to third nozzles, the spraying direction of the third nozzles at the upper end of the first washing tower is set upward, and the spraying direction of the third nozzles at the lower end of the first washing tower is set downward.

[0019] Optionally, an annular pipe is provided on the circumference of the first washing tower, a connecting branch pipe is provided at the bottom end of the annular pipe, the connecting branch pipe is connected to the elastic bellows, and the elastic bellows is connected to the connecting elbow; a transverse connecting flange pipe is provided on the outer wall of the first washing tower, one end of the third nozzle has a first mounting flange, and the first mounting flange is connected to the connecting elbow, a second mounting flange is also provided on the outer wall of the third nozzle, and the third nozzle is connected to the transverse connecting flange pipe through the second mounting flange.

[0020] Optionally, a circulating water outlet is provided at the bottom of the first washing tower, and the circulating water outlet is connected to the third nozzle through pipe one, and a circulating pump is provided on pipe one.

[0021] Optionally, a first slag discharge port is provided at the bottom end of the first settling pipe, and a second slag discharge port is provided at the bottom end of the second settling pipe; a discharge pipe for discharging silica gel and flushing water is provided at the bottom end of the exhaust fan.

[0022] Optionally, a water supply pipe is provided at the bottom end of the second sedimentation tube.

[0023] The utility model has the following advantages and beneficial effects:

[0024] The device has a simple and novel design and low investment cost. It can effectively separate and remove solid phases such as silica gel precipitated from the extraction tail gas during the washing process. It is easy to maintain and prolongs the operation cycle of the device.

[0025] (1) Use a pipe scrubber, add a pipe scrubber settling section, place it directly on the ground, integrate washing, settling and support, and discharge most of the silica gel in the pipe scrubber;

[0026] (2) The vertical pipe section of the pipeline scrubber is equipped with multiple spray devices, plus vertical spray at the elbow at the end of the gas phase horizontal pipe, forming a three-stage washing process. By increasing the spray density to wash the exhaust gas, it also plays a role in flushing the wall deposits in the pipeline;

[0027] (3) A settling section is added at the bottom of the pipeline scrubber. The settling section has a certain liquid level. The solid phase entrained by the gas has inertia in the straight pipe section. When the solid phase contacts the liquid surface, it is captured, and most of the solid phase washed by the through-pipe scrubber is separated from the gas;

[0028] (4) The solid phase and washing water washed by the modified gas phase horizontal pipe and through-pipe scrubber are separated for the first time in the first settling pipe of the through-pipe scrubber, and the gas-liquid and gas-solid separation is achieved for the second time in the first scrubber. The solid phase and condensate entrained by the gas at the top outlet of the first scrubber are separated for the third time at the bottom of the second settling pipe before entering the exhaust fan, which completely solves the problem of silica gel backward migration and extends the normal operation cycle of the exhaust fan from 3-7 days to about two years.

[0029] (5) The entire exhaust gas washing system does not have problems such as nozzles, pipe blockage, and washing tower wall hangings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A structural diagram of a tail gas washing and separation device for a wet phosphoric acid extraction tank provided in the prior art;

[0031] Figure 2 A structural diagram of the tail gas washing and separation device of the wet phosphoric acid extraction tank provided by the utility model;

[0032] Figure 3 The structural diagram of the gas phase horizontal pipe and the bent pipe provided by the utility model;

[0033] Figure 4 A structural diagram of the spray device on the first washing tower provided by the utility model;

[0034] Icons: 1-extraction tank, 2-gas phase horizontal pipe, 21-elbow pipe, 22-first nozzle, 221-first nozzle, 23-vertical connecting flange pipe, 3-washing vertical pipe, 31-gas outlet horizontal pipe, 32-second nozzle, 4-first settling pipe, 41-first slag discharge port, 42-pipeline two, 5-first washing tower, 51-annular pipe, 511-connecting branch pipe, 512-elastic bellows, 513-connecting elbow, 52-third nozzle, 521-first mounting flange, 522-second mounting flange, 523-third nozzle, 53-pipeline one, 54-circulation pump, 55-slag discharge pump, 56-horizontal connecting flange pipe, 57-circulation water outlet, 58-third slag discharge port, 6-exhaust pipeline, 7-second settling pipe, 71-second slag discharge port, 72-pipeline three, 73-water supply pipe, 8-exhaust fan. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example

[0038] like Figures 2 to 4 As shown, a tail gas washing and separation device for a wet phosphoric acid extraction tank comprises an extraction tank 1, a pipe scrubber, a first washing tower 5 and a tail gas fan 8, wherein the upper end of the extraction tank 1 is connected to the air inlet of the pipe scrubber, the air outlet on the bottom side of the pipe scrubber is connected to the first washing tower 5, and the bottom end of the pipe scrubber is connected to the first settling pipe 4; the upper end of the first washing tower 5 is connected to the tail gas fan 8 through a tail gas pipe 6, and the bottom end of the tail gas pipe 6 is connected to the second settling pipe 7; the first settling pipe 4, the second settling pipe 7 and the bottom end of the first washing tower 5 are respectively connected to a slag discharge pump 55 through pipes, and the solid slag is discharged into the slag discharge tank through the slag discharge pump 55. Specifically, the bottom end of the first sedimentation tube 4 has an outlet and is connected to the second pipe 42, the bottom end of the second sedimentation tube 7 has an outlet and is connected to the third pipe 72, the second pipe 42 and the third pipe 72 are both connected to the slag discharge pump 55, and the bottom end of the first washing tower 5 is provided with a third slag discharge port 58, and the third slag discharge port 58 is connected to the slag discharge pump 55 through a pipe, so that the slag deposited in the three stages can be discharged.

[0039] The device has a simple and novel design and low investment cost. It can effectively separate and remove solid phases such as silica gel precipitated from the extraction tail gas during the washing process. It is easy to maintain and prolongs the operation cycle of the device.

[0040] In the utility model, a pipe scrubber is utilized, and a first settling pipe 4 is added and placed directly on the ground. The first settling pipe 4 has a certain liquid level, and the solid phase entrained by the gas has inertia in the washing vertical pipe 3. When the solid phase contacts the liquid surface, it is captured, and most of the solid phase washed down by the pipe scrubber is separated from the gas. The utility model integrates washing, settling and supporting in one, and most of the silica gel materials in the pipe scrubber can be discharged, thereby reducing the content of silica gel materials entering the first washing tower 5, and preventing silica gel materials from entering the subsequent washing system, thereby fundamentally solving the problem of blockage of the spray system and improving the spray efficiency.

[0041] The modified gas phase horizontal pipe 2, the solid phase washed out by the through-pipe scrubber, and the washing water are separated for the first time in the first settling pipe 4 of the through-pipe scrubber, and the gas-liquid and gas-solid are separated for the second time in the first washing tower 5. The solid phase and condensate entrained in the gas at the top outlet of the first washing tower 5 are separated for the third time at the bottom of the second settling pipe 7 before entering the exhaust gas fan 8, which completely solves the problem of silica gel backward migration, and the normal operating cycle of the exhaust gas fan 8 is extended from 3-7 days to about two years.

[0042] Furthermore, the pipeline scrubber is changed to a polymer tube lined one, because the polymer tube is smooth and the solid phase precipitated in the gas is not easy to stick to the wall. The scrubber includes a gas phase horizontal tube 2 and a washing vertical tube 3. The gas phase horizontal tube 2 is arranged at the upper end of the extraction tank 1, and the gas phase horizontal tube 2 extends downwardly in the direction of the washing vertical tube 3 at an inclination angle of a°. The air inlet of the gas phase horizontal tube 2 is connected to the extraction tank 1, and the bottom end of the washing vertical tube 3 is connected to the first sedimentation tube 4. The gas phase horizontal tube 2 is inclined, and the spray device is cancelled on the gas phase horizontal tube 2, which can avoid a large amount of silica gel from cooling down rapidly and precipitating, thereby blocking the gas phase horizontal tube 2. To solve the problem of rapid cooling of the high-temperature gas coming out of the extraction tank 1, the gas phase horizontal tube 2 is arranged at a certain angle along the airflow direction to solve the problem of water accumulation in the gas phase horizontal tube 2, which aggravates the precipitation of silica gel and sticking to the wall after contact with the fluorine-containing gas at about 85°C.

[0043] Furthermore, one end of the gas phase horizontal pipe 2 is connected to the curved pipe 21, the bottom end of the curved pipe 21 is connected to the washing vertical pipe 3, a vertically arranged first nozzle 22 is arranged on the top of the curved pipe 21, a vertically connected flange pipe 23 is arranged on the top of the curved pipe 21, the first nozzle 22 extends into the curved pipe 21 through the vertical connecting flange pipe 23, the first nozzle 22 is connected to the vertical connecting flange pipe 23, and a first nozzle 221 is connected to the end of the first nozzle 22, the first nozzle 221 is used to spray the curved inner wall of the curved pipe 21, and can also spray and cool the gas inside the pipeline.

[0044] Furthermore, the washing vertical pipe 3 is provided with a plurality of transversely arranged second spray pipes 32 along the height direction. The second spray pipes 32 extend into the washing vertical pipe 3 , and the ends of the second spray pipes 32 are connected with second spray heads.

[0045] In the utility model, the nozzle can be changed into a rotating nozzle that sprays water at 120°, so as to solve the problems that the water cannot be spread, the washing angle is not enough, and the tower wall and the pipe wall cannot be washed. The three sections of the washing vertical pipe of the pipe scrubber are provided with multiple sets of spray devices, and the vertical spray at the end bend 21 of the gas phase horizontal pipe 2 is added to form a three-stage washing. By increasing the spray density to wash the tail gas, it plays the role of washing the wall materials in the pipe.

[0046] Furthermore, the angle a between the gas phase horizontal pipe 2 and the horizontal plane is 5°.

[0047] Furthermore, the first washing tower 5 is provided with a plurality of third spray pipes 52 arranged transversely along the height direction, the third spray pipes 52 extend into the first washing tower 5, and the third nozzle 523 is connected to the end of the third spray pipe 52, the spray direction of the third nozzle 523 at the upper end of the first washing tower 5 is set upward, and the spray direction of the third nozzle 523 at the lower end of the first washing tower 5 is set downward. Through the spray design with different spray directions, the spray efficiency can be improved while the inner wall of the first washing tower 5 is fully flushed to reduce the accumulation of materials on the inner wall of the tower. The entire tail gas washing system does not have problems such as nozzle and pipeline blockage and washing tower wall hanging materials.

[0048] Furthermore, the circumference of the first washing tower 5 is provided with an annular pipe 51, the bottom end of the annular pipe 51 is provided with a connecting branch pipe 511, the connecting branch pipe 511 is connected to an elastic bellows 512 (expansion joint), and the elastic bellows 512 is connected to a connecting elbow 513; the outer wall of the first washing tower 5 is provided with a transverse connecting flange pipe 56, one end of the third spray pipe 52 has a first mounting flange 521, and the first mounting flange 521 is connected to the connecting elbow 513, the outer wall of the third spray head 523 is also provided with a second mounting flange 522, and the third spray pipe 52 is connected to the transverse connecting flange pipe 56 through the second mounting flange 522. This connection structure makes it easy to realize the disassembly and assembly of the third spray pipe and the third spray head 523; the connection is made through the expansion joint to eliminate the influence of temperature changes and vibrations generated during system operation on the spray system.

[0049] Two sets of spray devices are arranged on the upper and lower layers of the first washing tower 5, and three third spray pipes 52 are evenly distributed in the circumferential direction on each layer. The third nozzles 523 of the upper and lower layers are staggered at 60 degrees to achieve spray washing without dead angles; the spray direction of the upper layer is upward, which prolongs the gas-liquid contact time and improves the washing effect. On the other hand, when the liquid sprays upward and falls back, part of it can clean the tower wall when it reaches the wall of the washing tower, reducing the crystallization of attachments on the tower wall into large particles and avoiding clogging of the nozzles; the three sets of spray devices on the lower layer are downward, and it is also necessary to ensure that the tower wall can be washed.

[0050] Furthermore, a circulating water outlet 57 is provided at the bottom of the first washing tower 5 , and the circulating water outlet 57 is connected to the third nozzle 52 through a pipe 1 53 , and a circulating pump 54 is provided on the pipe 1 53 , thereby realizing the circulating spraying operation of the exhaust gas in the first washing tower 5 .

[0051] Furthermore, a first slag discharge port 41 is provided at the bottom end of the first settling tube 4, and a second slag discharge port 71 is provided at the bottom end of the second settling tube 7, so that the slag discharge operation can be realized; a discharge pipe for discharging silica gel and flushing water is provided at the bottom end of the exhaust fan 8, so that the slag inside the exhaust fan 8 can be cleared.

[0052] Furthermore, a water supply pipe 73 is provided at the bottom end of the second settling tube 7. Since the material reaching the inside of the second settling tube 7 contains relatively less water, it enters through the water supply pipe 73 to form a slag-water mixture in the second settling tube 7, which is easier to be pumped away and discharged by the slag discharge pump 55.

[0053] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A tail gas washing and separation device for a wet phosphoric acid extraction tank, characterized in that : including extraction tank, pipeline scrubber, first scrubber and tail gas fan, The upper end of the extraction tank is connected to the air inlet of the pipeline scrubber, the air outlet on the bottom side of the pipeline scrubber is connected to the first washing tower, and the bottom end of the pipeline scrubber is connected to the first settling pipe; The upper end of the first washing tower is connected to the exhaust gas fan through an exhaust gas pipeline, and the bottom end of the exhaust gas pipeline is connected to the second settling pipe; The first settling pipe, the second settling pipe and the bottom end of the first washing tower are connected through pipelines and slag discharge pumps respectively.

2. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 1, characterized in that: The pipeline scrubber includes a gas phase horizontal pipe and a washing vertical pipe. The gas phase horizontal pipe is arranged at the upper end of the extraction tank and extends downwardly in an inclined direction toward the washing vertical pipe. The air inlet of the gas phase horizontal pipe is connected to the extraction tank, and the bottom end of the washing vertical pipe is connected to the first settling pipe.

3. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 2, characterized in that: One end of the gas phase horizontal pipe is connected to the curved pipe, the bottom end of the curved pipe is connected to the washing vertical pipe, a vertically arranged first nozzle is arranged on the top of the curved pipe, the first nozzle extends into the curved pipe, the end of the first nozzle is connected to a first nozzle, and the first nozzle is used to spray the curved inner wall of the curved pipe.

4. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 3, characterized in that: The vertical washing pipe is provided with a plurality of second spray pipes arranged transversely along the height direction. The second spray pipes extend into the vertical washing pipe, and the ends of the second spray pipes are connected with second spray heads.

5. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 3, characterized in that: The angle between the gas phase horizontal tube and the horizontal plane is 5°.

6. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 4, characterized in that: The first washing tower is provided with a plurality of transversely arranged third nozzles along the height direction, the third nozzles extend into the first washing tower, the ends of the third nozzles are connected with third nozzles, the spraying direction of the third nozzles at the upper end of the first washing tower is set upward, and the spraying direction of the third nozzles at the lower end of the first washing tower is set downward.

7. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 6, characterized in that: The circumference of the first washing tower is provided with an annular pipe, and the bottom end of the annular pipe is provided with a connecting branch pipe, the connecting branch pipe is connected to the elastic bellows, and the elastic bellows is connected to the connecting elbow; the outer wall of the first washing tower is provided with a transverse connecting flange pipe, one end of the third nozzle has a first mounting flange, and the first mounting flange is connected to the connecting elbow, the outer wall of the third nozzle is also provided with a second mounting flange, and the third nozzle is connected to the transverse connecting flange pipe through the second mounting flange.

8. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 1, characterized in that: A circulating water outlet is arranged at the bottom of the first washing tower, and the circulating water outlet is connected to the third spray pipe through a pipe 1, and a circulating pump is arranged on the pipe 1.

9. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 1, characterized in that: The bottom end of the first settling pipe is provided with a first slag discharge port, and the bottom end of the second settling pipe is provided with a second slag discharge port; the bottom end of the tail gas fan is provided with a discharge pipe for discharging silica gel and flushing water.

10. The tail gas washing and separation device of the wet phosphoric acid extraction tank according to claim 1, characterized in that: A water supply pipe is arranged at the bottom end of the second sedimentation pipe.

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