Device for improving fluorine recovery rate in wet-process phosphoric acid concentration process

Abstract

The utility model relates to the technical field of wet-process phosphoric acid concentration production equipment, in particular to a device for improving the fluorine recovery rate in the wet-process phosphoric acid concentration process, which comprises a demister, a first washing tower connected to one end of the demister, a second washing tower connected to one end of the first washing tower, and a heat exchanger connected to one end of the second washing tower. The bottom end of the heat exchanger is connected with a condensation water tank, one side of the top of the condensation water tank is connected with a gas exhaust pipe, the other side of the top of the condensation water tank is provided with a liquid inlet pipe, and one side of the bottom of the condensation water tank is connected with a condensation water pipe. According to the device for improving the fluorine recovery rate in the wet-process phosphoric acid concentration process, the problems of fluorine escape and loss in the wet-process phosphoric acid concentration process are effectively solved through optimization design and integration of key components. According to the device, a series structure of the demister, the first washing tower, the second washing tower and the heat exchanger is utilized, so that multi-stage washing and efficient recovery of fluorine-containing gas are realized.

Description

Technical Field

[0001] The utility model relates to the technical field of wet-process phosphoric acid concentration production equipment, in particular to a device for improving the fluorine recovery rate in the wet-process phosphoric acid concentration process. Background Art

[0002] The wet-process phosphoric acid concentration process typically uses a sulfuric acid-based dihydrate process. This process produces dilute phosphoric acid with a concentration of approximately 26% and contains approximately 2% fluorine. To achieve a higher concentration, the dilute phosphoric acid undergoes aging and clarification, with the top portion of the clear acid then being sent to a concentration unit. During this concentration process, the phosphoric acid is indirectly heated by steam through a heat exchanger, causing the circulating phosphoric acid to continuously evaporate and dehydrate, ultimately concentrating to a concentration of approximately 48%. During the concentration process, fluorine in the acid will escape to varying degrees as the water vapor escapes, entering the fluorine-containing gas scrubbing system.

[0003] Despite scrubbing and absorption, approximately 5% of the fluorine remains unabsorbed and remains in the scrubbed gas, entering the atmospheric condenser. During the condensation process, it is condensed and liquefied by the circulating cooling water. This not only increases the circulating water temperature, necessitating additional air cooling at a circulating water station, but also partially releases the fluorine in the water back into the atmosphere with the cooling air during the cooling process, resulting in fluorine loss, reduced fluorine recovery yield, and adversely impacting the surrounding environment. Therefore, effectively reducing fluorine leakage and loss and improving fluorine recovery efficiency have become urgent challenges in the wet-process phosphoric acid concentration production process. Utility Model Content

[0004] The purpose of the utility model is to provide a device for improving the fluorine recovery rate in the wet-process phosphoric acid concentration process, so as to solve the problem proposed in the above-mentioned background art that the circulating water temperature rises and needs to be sent to a circulating water station for air cooling. In addition, during the cooling process, part of the fluorine in the water will be released back into the atmosphere with the cooling air, resulting in fluorine loss, reducing the fluorine recovery yield, and having an adverse impact on the surrounding environment.

[0005] To achieve the above-mentioned objectives, the present invention provides a device for improving the fluorine recovery rate in the wet-process phosphoric acid concentration process, comprising a demister, one end of the demister being connected to a first scrubbing tower, one end of the first scrubbing tower being connected to a second scrubbing tower, one end of the second scrubbing tower being connected to a heat exchanger, the bottom end of the heat exchanger being connected to a condensate tank, one side of the top of the condensate tank being connected to a gas exhaust pipe, the other side of the top of the condensate tank being provided with a liquid inlet pipe, and one side of the bottom of the condensate tank being connected to a condensate pipe.

[0006] Preferably, the gas exhaust pipe is connected to a vacuum pump, and the condensate water pipe is installed with a condensate water pump.

[0007] Preferably, an upper tube plate is installed above the interior of the heat exchanger, and a lower tube plate is installed below the interior of the heat exchanger. A plurality of heat exchange tubes are installed between the upper tube plate and the lower tube plate. A heat exchange space is provided between the upper tube plate and the lower tube plate. The upper side of the heat exchange space is connected to a water outlet pipe, and the lower side of the heat exchange space is connected to a water inlet pipe.

[0008] Preferably, a plurality of through holes are opened on the surfaces of the upper tube plate and the lower tube plate, and the upper and lower ends of the heat exchange tubes are connected to the through holes.

[0009] Preferably, the liquid inlet pipe is inserted into the condensation water tank, the end of the liquid inlet pipe is lower than the end of the gas exhaust pipe, and a guide plate is obliquely provided inside the gas exhaust pipe.

[0010] Preferably, the through holes are arranged evenly.

[0011] Preferably, a slag discharge pipe is connected to one side of the bottom of the condensation water tank, and a sealing cover is installed on the outside of the slag discharge pipe.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] This device, designed to improve fluorine recovery during wet-process phosphoric acid concentration, effectively addresses the issue of fluorine leakage and loss during the process by optimizing its design and integrating key components. The device utilizes a series configuration of a demister, a primary scrubber, a secondary scrubber, and a heat exchanger to achieve multi-stage scrubbing and efficient recovery of fluorine-containing gases.

[0014] In particular, the condensate tank located after the heat exchanger, through the ingenious design of the liquid inlet pipe, gas outlet pipe, and guide plate, not only improves condensation efficiency but also effectively prevents the re-escape of fluorine. Furthermore, the coordinated use of the vacuum pump and condensate pump further enhances the system's fluorine recovery rate. Overall, this device significantly improves the efficiency of phosphoric acid concentration and the recovery rate of fluorine, reduces pollution to the surrounding environment, and has significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0016] Figure 2 This is a schematic structural diagram of the heat exchanger in the present utility model;

[0017] Figure 3 This is a schematic diagram of the structure of the condensation water tank in the utility model;

[0018] Figure 4 This is a structural diagram of the upper tube plate in the utility model;

[0019] The meaning of each number in the figure is:

[0020] 1. Defoamer; 2. First scrubber; 3. Second scrubber; 4. Heat exchanger; 41. Upper tube sheet; 411. Through hole; 42. Heat exchange tube; 43. Lower tube sheet; 44. Water outlet pipe; 45. Water inlet pipe; 5. Condensate tank; 51. Liquid inlet pipe; 52. Guide plate; 53. Gas discharge pipe; 54. Condensate pipe; 55. Slag discharge pipe; 6. Condensate pump; 7. Vacuum pump. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] The utility model provides a device for improving the fluorine recovery rate in the wet-process phosphoric acid concentration process. Figure 1-Figure 4 As shown, it includes a demister 1, one end of which is connected to a first scrubber 2, one end of which is connected to a second scrubber 3, one end of which is connected to a heat exchanger 4, the bottom end of which is connected to a condensate tank 5, one side of the top of which is connected to a gas discharge pipe 53, the other side of which is provided with a liquid inlet pipe 51, and the bottom side of which is connected to a condensate pipe 54. The device first uses the demister 1 to effectively remove foam and impurities in the fluorine-containing tail gas, and then performs multi-stage scrubbing of the fluorine-containing gas through the first scrubber 2 and the second scrubber 3 connected in series, significantly improving the fluorine absorption efficiency.

[0023] The treated fluorine-containing tail gas indirectly exchanges heat with circulating cooling water in heat exchanger 4, where it is further condensed into fluorine-containing water, which enters condensate tank 5. A gas discharge pipe 53, connected to one side of condensate tank 5, works in conjunction with a vacuum pump 7 to remove non-condensable gases from the fluorine-containing water. A condensate pipe 54, connected to the other side, is driven by a condensate pump and transports the fluorine-containing water to the phosphoric acid filtration system for recovery. This design significantly improves fluorine recovery and utilization, effectively solving the problem of fluorine escape and loss during the wet-process phosphoric acid concentration process, while also reducing pollution to the surrounding environment, demonstrating significant economic and environmental benefits.

[0024] Specifically, an upper tube sheet 41 is installed above the interior of the heat exchanger 4, and a lower tube sheet 43 is installed below the interior of the heat exchanger 4. Several heat exchange tubes 42 are installed between the upper and lower tube sheets 41, 43. A heat exchange space is provided between the upper and lower tube sheets 41, 43. An outlet pipe 44 is connected to the upper side of the heat exchange space, and an inlet pipe 45 is connected to the lower side of the heat exchange space. This design not only increases the heat exchange area and improves heat exchange efficiency, but also, through the rational arrangement of the inlet and outlet pipes 45, achieves smooth circulation of cooling water, helps maintain the stable operation of the heat exchanger 4, and thereby reduces steam consumption. Fluorine-containing exhaust gas enters the heat exchange tubes 42 in the tube path. The cooling water flows through the inlet and outlet pipes, indirectly exchanging heat with the fluorine-containing gas in the heat exchange tubes 42.

[0025] Furthermore, the surfaces of the upper tube sheet 41 and the lower tube sheet 43 are provided with a number of through holes 411, to which the upper and lower ends of the heat exchange tubes 42 are connected. This uniform arrangement not only ensures the secure installation of the heat exchange tubes 42, but also optimizes the flow path of the fluid within the heat exchanger 4, reduces flow resistance, and further improves heat exchange efficiency.

[0026] Furthermore, the liquid inlet pipe 51 and the gas exhaust pipe 53 of the condensation water tank 5 are both inserted into the condensation water tank 5, and the end of the liquid inlet pipe 51 is lower than the end of the gas exhaust pipe 53. The fluorine-containing water containing non-condensable gas enters the condensation water tank 5 from the liquid inlet pipe 51. The fluorine-containing water accumulates in the condensation water tank 5 under the action of gravity, and the non-condensable gas is discharged from the gas exhaust pipe 53 under the action of the vacuum pump 7. A guide plate 52 is obliquely arranged inside the gas exhaust pipe 53. The guide plate 52 is staggered and arranged obliquely upward to further block the droplets in the non-condensable gas and reduce the discharge of droplets with the non-condensable gas.

[0027] Furthermore, the through holes 411 are evenly arranged, which is not only beautiful but also more importantly optimizes the distribution of the fluid in the heat exchanger 4, reduces dead angles and eddy currents, and thus improves the heat exchange efficiency and the overall performance of the device.

[0028] Furthermore, a slag discharge pipe 55 is connected to one side of the bottom of the condensate tank 5, and a sealing cover is installed on the outside of the slag discharge pipe 55. When a certain amount of impurities and dirt accumulates in the condensate tank 5, the sealing cover can be opened and the slag discharge pipe 55 can be used to promptly discharge the impurities and dirt, thereby maintaining the cleanliness and efficient operation of the condensate tank 5. This design not only extends the service life of the equipment, but also improves the stability and maintenance convenience of the system.

[0029] During use, the present invention's device for improving fluorine recovery during wet-process phosphoric acid concentration begins by introducing fluorine-containing tail gas into a demister 1. The demister 1 effectively removes foam and impurities from the tail gas, ensuring smooth subsequent processing. The defoamed tail gas then enters a first scrubber 2, where the fluorine-containing gas undergoes initial contact and scrubbing with a scrubbing solution, partially absorbing the fluorine. Subsequently, the tail gas enters a second scrubber 3 for deeper scrubbing, further improving fluorine absorption efficiency. This dual-stage scrubber process significantly reduces the fluorine content in the tail gas.

[0030] After washing, the small amount of fluorine-containing tail gas enters heat exchanger 4. Heat exchanger 4 is equipped with an upper tube sheet 41, a lower tube sheet 43, and several heat exchange tubes 42, forming a highly efficient heat exchange space. Cooling water enters the lower portion of the heat exchange space through an inlet pipe 45, absorbs heat, and is discharged through an outlet pipe 44, thus achieving cooling water recycling. Within this heat exchange space, the fluorine-containing tail gas indirectly exchanges heat with the cooling water outside the heat exchange tubes 42. Part of the gas and the fluorine-containing part condenses into fluorine-containing water, which, along with some non-condensable gases, enters the condensate tank 5.

[0031] The upper and lower ends of the heat exchange tube 42 are firmly connected through the through holes 411 on the upper tube plate 41 and the lower tube plate 43. This uniform arrangement design optimizes the flow path of the fluid in the heat exchanger 4, reduces flow resistance, and improves heat exchange efficiency.

[0032] In the condensate tank 5, fluorine-containing water and non-condensable gas enter from the liquid inlet pipe 51, and are separated from the fluorine-containing water and the non-condensable gas in the condensate tank 5. The fluorine-containing water is sent to the phosphoric acid filtration system for recovery through the condensate pipe 54 and the condensate pump 6. The non-condensable gas enters the gas exhaust pipe 53 and is promptly emptied under the action of the vacuum pump 7.

[0033] A slag discharge pipe 55 is connected to one side of the bottom of the condensate tank 5. When a certain amount of impurities and dirt accumulates in the condensate tank 5, the slag discharge pipe 55 can be promptly discharged by opening the sealing cover, thereby keeping the condensate tank 5 clean and operating efficiently. This design not only extends the service life of the equipment, but also improves the stability of the system and the ease of maintenance.

[0034] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for improving the fluorine recovery rate in the wet-process phosphoric acid concentration process, comprising a demister (1), characterized in that: One end of the demister (1) is connected to a first washing tower (2), one end of the first washing tower (2) is connected to a second washing tower (3), one end of the second washing tower (3) is connected to a heat exchanger (4), the bottom end of the heat exchanger (4) is connected to a condensation water tank (5), one side of the top of the condensation water tank (5) is connected to a gas discharge pipe (53), the other side of the top of the condensation water tank (5) is provided with a liquid inlet pipe (51), and one side of the bottom of the condensation water tank (5) is connected to a condensation water pipe (54).

2. The device for improving fluorine recovery in the wet-process phosphoric acid concentration process according to claim 1, characterized in that: The gas exhaust pipe (53) is connected to a vacuum pump (7), and the condensate water pipe (54) is installed with a condensate water pump (6).

3. The device for improving fluorine recovery in the wet-process phosphoric acid concentration process according to claim 1, characterized in that: An upper tube plate (41) is installed above the interior of the heat exchanger (4), and a lower tube plate (43) is installed below the interior of the heat exchanger (4). A plurality of heat exchange tubes (42) are installed between the upper tube plate (41) and the lower tube plate (43). A heat exchange space is provided between the upper tube plate (41) and the lower tube plate (43). An outlet pipe (44) is connected to the upper side of the heat exchange space, and an inlet pipe (45) is connected to the lower side of the heat exchange space.

4. The device for improving fluorine recovery in the wet-process phosphoric acid concentration process according to claim 3, characterized in that: A plurality of through holes (411) are provided on the surfaces of the upper tube plate (41) and the lower tube plate (43), and the upper and lower ends of the heat exchange tube (42) are connected to the through holes (411).

5. The device for improving fluorine recovery in the wet-process phosphoric acid concentration process according to claim 1, characterized in that: The liquid inlet pipe (51) is inserted into the condensation water tank (5), the end of the liquid inlet pipe (51) is lower than the end of the gas discharge pipe (53), and a guide plate (52) is obliquely provided inside the gas discharge pipe (53).

6. The device for improving fluorine recovery in the wet-process phosphoric acid concentration process according to claim 4, characterized in that: The through holes (411) are arranged evenly.

7. The device for improving fluorine recovery in the wet-process phosphoric acid concentration process according to claim 1, characterized in that: A slag discharge pipe (55) is connected to one side of the bottom of the condensation water tank (5), and a sealing cover is installed on the outside of the slag discharge pipe (55).

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