Acid mixing device for wet-process phosphoric acid

Abstract

The utility model discloses an acid mixing device for wet-process phosphoric acid, which relates to the technical field of chemical production equipment and comprises a mixing barrel, a first flange is arranged at the top of the mixing barrel, the top of the mixing barrel is sealed by the first flange, a sulfuric acid barrel is sleeved in the mixing barrel, the sulfuric acid barrel penetrates through the first flange to be mounted in the mixing barrel, and a plurality of acid outlet holes are formed in the sulfuric acid barrel; the side wall of the mixing barrel is connected with an acid return feeding pipe, and a discharging opening is formed in the bottom of the mixing barrel; the mixing cylinder is further connected with a smoke pipe, an inlet of the smoke pipe is led out from the top of the mixing cylinder, an outlet of the smoke pipe is led in from the bottom of the mixing cylinder, and a waterproof breathable film is arranged at the joint of the outlet of the smoke pipe and the mixing cylinder. Through the arrangement of the flue gas pipe, flue gas generated in the mixing cylinder during mixing enters the flue gas pipe and then enters the mixing cylinder for the second time, material loss is reduced, upward bubbles are formed in the mixing cylinder, the mixing effect of mixed acid is further enhanced, meanwhile, stirring generated by upward bubbles can accelerate heat dispersion, and the mixing efficiency is improved. The heat generated by the mixed acid is further dispersed.

Description

Technical Field

[0001] This utility model relates to the field of chemical production equipment technology, specifically to a mixed acid device for wet-process phosphoric acid. Background Technology

[0002] Phosphoric acid is an important chemical raw material, mainly used in the pharmaceutical, food, and fertilizer industries. Industrially, wet processing is commonly used to produce it, with sulfuric acid and phosphate rock as the main raw materials.

[0003] Phosphoric acid has a wide range of applications in agriculture, industry, food processing, and medicine. Among these, monoammonium phosphate (MAP), diammonium phosphate (DAP), and numerous compound fertilizers synthesized from MAP as an intermediate product are important uses of MAP, and its application in agricultural fertilizers has a long history. Industrially, MAP production is mainly divided into two methods: thermal and wet processes. Due to the severe environmental pollution caused by the thermal process, and the significant environmental pressure on enterprises, industrial MAP production now primarily uses the wet process. Sulfuric acid and phosphoric acid are the mainstream methods for preparing wet-process MAP.

[0004] In existing wet-process phosphoric acid plants, the current technology generally involves mixing concentrated sulfuric acid and phosphoric acid back acid once before directly entering the extraction process. Because a large amount of heat and flue gas are released during the mixing process, not only will material loss occur, but the released heat will also be directly transferred to the reaction tank, causing temperature fluctuations in the reaction tank and affecting the crystallization effect of the reaction tank. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a mixed acid device for wet phosphoric acid production.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] A wet-process phosphoric acid mixing device includes a mixing cylinder with a first flange at the top, which seals the top of the mixing cylinder. A sulfuric acid cylinder is installed inside the mixing cylinder, passing through the first flange. The sulfuric acid cylinder has several acid outlet holes. A return acid feed pipe is connected to the side wall of the mixing cylinder, and a discharge port is opened at the bottom of the mixing cylinder. A flue gas pipe is also connected to the mixing cylinder, with the flue gas inlet extending from the top of the mixing cylinder and the flue gas outlet extending from the bottom of the mixing cylinder. A waterproof and breathable membrane is provided at the connection between the flue gas outlet and the mixing cylinder, and the waterproof and breathable membrane is made of polytetrafluoroethylene material.

[0008] The sulfuric acid cylinder is provided with a second flange at the interface between the first flange and the sulfuric acid cylinder. The sulfuric acid cylinder passes through the first flange and is detachably fixed inside the mixing cylinder through the second flange.

[0009] Preferably, the sulfuric acid cylinder has acid outlet holes on both the cylinder wall and the bottom, and the acid return feed pipe is set at an angle.

[0010] The flue pipe is equipped with a pressure relief branch pipe, and a pressure relief valve is installed on the pressure relief branch pipe.

[0011] Preferably, a cooling pipe is provided around the mixing cylinder.

[0012] Both the mixing cylinder and the sulfuric acid cylinder are equipped with level gauges to ensure that the liquid levels in the mixing cylinder and the sulfuric acid cylinder are the same.

[0013] The beneficial effects of this utility model are:

[0014] This invention relates to a wet-process phosphoric acid mixing device that thoroughly mixes concentrated sulfuric acid and phosphoric acid before the mixed acid enters the reaction tank. During mixing, sulfur trioxide fumes generated in the mixing drum are discharged from the top and then enter the bottom of the mixing drum for secondary washing to recover sulfur trioxide, reducing material loss. The fumes form upward bubbles in the mixing drum, further enhancing the mixing effect of the mixed acid. At the same time, the agitation generated by the upward bubbles can accelerate heat dissipation. Combined with the cooling pipes installed around the mixing drum, the heat generated by the mixed acid is further dispersed, ensuring the extraction effect of the mixed acid in the reaction tank. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model;

[0016] Figure 2 This is a schematic diagram of the bottom of the sulfuric acid cylinder;

[0017] In the diagram, 1-mixing cylinder, 2-acid return feed pipe, 3-sulfuric acid cylinder, 4-acid outlet, 5-flue gas pipe, 6-pressure relief branch pipe, 7-pressure valve, 8-discharge port, 9-first flange, 10-second flange, 11-cooling pipe, 12-waterproof and breathable membrane. Detailed Implementation

[0018] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0019] See Figure 1-2 This utility model provides a technical solution:

[0020] A wet-process phosphoric acid mixing device includes a mixing cylinder 1, a sulfuric acid cylinder 3, and a flue gas pipe 5. A first flange 9 is provided at the top of the mixing cylinder 1, sealing the top of the mixing cylinder 1. The sulfuric acid cylinder 3 passes through the first flange 9 and is fitted inside the mixing cylinder 1. A second flange 10 is provided at the interface between the sulfuric acid cylinder 3 and the first flange 9, fixing the sulfuric acid cylinder 3 to the mixing cylinder 1. The sulfuric acid cylinder 3 has uniformly distributed acid outlet holes 4 on its wall and bottom. Concentrated sulfuric acid overflows from the acid outlet holes 4 and mixes with the phosphoric acid in the mixing cylinder 1. The inlet of the flue gas pipe 5 is connected to the top of the mixing cylinder 1, and the outlet is connected to the bottom of the mixing cylinder 1. A waterproof and breathable membrane 12 is provided at the connection between the outlet of the flue gas pipe 5 and the mixing cylinder 1. A pressure relief branch pipe 6 is provided on the flue gas pipe 5, and a pressure relief valve 7 is provided on the pressure relief branch pipe 6. When the pressure in the flue gas pipe 5 is too high, the pressure relief valve 7 opens to release the pressure. A discharge port 8 is opened at the bottom of the mixing cylinder 1, and a return acid feed pipe 2 is connected to the side wall of the mixing cylinder 1. The return acid feed pipe 2 is set at an angle, and a cooling pipe 11 is wrapped around the mixing cylinder 1 to cool it down. Both the mixing cylinder 1 and the sulfuric acid cylinder 3 are equipped with level gauges to ensure that the liquid levels in the two cylinders are the same.

[0021] In this embodiment, the waterproof and breathable membrane 12 is made of expanded polytetrafluoroethylene (e-PTFE) resistant to strong acids and breathable membrane, with a waterproof rating of IP67 / 68 and a temperature range of -200℃ to 260℃.

[0022] All flanges are fastened with bolts. Removing the second flange 10 allows the sulfuric acid cylinder 3 to be taken out of the mixing cylinder 1 for cleaning. Removing the first flange 9 and the second flange 10 allows for simultaneous cleaning of both the sulfuric acid cylinder 3 and the mixing cylinder 1. Alternatively, if the raw materials used are not prone to fouling, the flange connection can be selectively replaced with welding.

[0023] The acid return feed pipe 2 is set at an angle. When acid return (phosphoric acid) is fed, the acid return enters in a tangential manner, which can form a vortex fluid in the mixing cylinder 1. This can increase the contact area with concentrated sulfuric acid, enhance the mixing effect, and better remove the heat generated by the dilution of concentrated sulfuric acid. At the same time, it forms an impact force, making it difficult for sediment to form in the mixing cylinder 1.

[0024] During operation, the mixing of concentrated sulfuric acid and phosphoric acid in mixing cylinder 1 generates a large amount of heat, producing flue gas in mixing cylinder 1. This flue gas primarily contains sulfur trioxide. The flue gas enters flue gas pipe 5 from the top of mixing cylinder 1 and is then discharged through flue gas pipe 5 to the bottom of mixing cylinder 1. The flue gas is further washed by the mixed acid, absorbing the sulfur trioxide. Meanwhile, the flue gas entering from the bottom of mixing cylinder 1 forms upward-moving bubbles, stirring the mixed acid and enhancing the mixing effect of the two acids. This also helps to better remove the heat generated by the dilution of concentrated sulfuric acid. Simultaneously, to ensure the normal operating pressure of the entire device, a pressure relief branch pipe 6 is installed on flue gas pipe 5. When the pressure in the pipe exceeds the threshold of pressure valve 7, the pressure relief branch pipe 6 discharges gas from the device to reduce the device pressure and ensure operational safety. Once the normal pressure is restored, the pressure relief branch pipe 6 is closed.

[0025] In this embodiment, both the wall and bottom of the sulfuric acid cylinder 3 have acid outlet holes 4. The acid outlet holes 4 increase the diffusion area of ​​concentrated sulfuric acid and enhance the mixing effect. The acid outlet holes 4 at the bottom of the sulfuric acid cylinder 3 prevent dead zones from forming at the bottom. To ensure the mixing effect, level gauges are installed in both the mixing cylinder 1 and the sulfuric acid cylinder 3 to ensure that the liquid levels in the two cylinders are the same, preventing the formation of a level difference that could cause one acid to enter the other acid through the acid outlet hole 4 and cause a violent reaction on the surface of the other acid.

[0026] The above description is merely a preferred embodiment of this utility model. It should be understood that this utility model is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this utility model should be protected within the scope of the appended claims.

Claims

1. A mixed acid apparatus for wet-process phosphoric acid production, characterized in that: The system includes a mixing cylinder (1), a first flange (9) on the top of the mixing cylinder (1) sealing the top of the mixing cylinder (1), a sulfuric acid cylinder (3) inside the mixing cylinder (1) and the sulfuric acid cylinder (3) passing through the first flange (9) and installed inside the mixing cylinder (1), and a number of acid outlet holes (4) on the sulfuric acid cylinder (3); a return acid feed pipe (2) is connected to the side wall of the mixing cylinder (1), and a discharge port (8) is opened at the bottom of the mixing cylinder (1); a flue gas pipe (5) is also connected to the mixing cylinder (1), the inlet of the flue gas pipe (5) is connected from the top of the mixing cylinder (1), the outlet of the flue gas pipe (5) is connected from the bottom of the mixing cylinder (1), and a waterproof and breathable membrane (12) is provided at the connection between the outlet of the flue gas pipe (5) and the mixing cylinder (1).

2. The mixed acid apparatus for wet-process phosphoric acid production according to claim 1, characterized in that: A second flange (10) is provided at the interface between the sulfuric acid cylinder (3) and the first flange (9). The sulfuric acid cylinder (3) passes through the first flange (9) and is detachably fixed inside the mixing cylinder (1) through the second flange (10).

3. The mixed acid apparatus for wet-process phosphoric acid production according to claim 1, characterized in that: The sulfuric acid cylinder (3) has acid outlet holes (4) on both the cylinder wall and the bottom.

4. The mixed acid apparatus for wet-process phosphoric acid production according to claim 1, characterized in that: The acid return feed pipe (2) is set at an angle.

5. The mixed acid apparatus for wet-process phosphoric acid production according to claim 1, characterized in that: The flue pipe (5) is provided with a pressure relief branch pipe (6), and a pressure relief valve (7) is installed on the pressure relief branch pipe (6).

6. The mixed acid apparatus for wet-process phosphoric acid production according to claim 1, characterized in that: The mixing cylinder (1) is surrounded by a cooling pipe (11).

7. The mixed acid apparatus for wet-process phosphoric acid production according to claim 1, characterized in that: Both the mixing cylinder (1) and the sulfuric acid cylinder (3) are equipped with level gauges to ensure that the liquid levels in the mixing cylinder (1) and the sulfuric acid cylinder (3) are the same.

8. The mixed acid apparatus for wet-process phosphoric acid production according to claim 1, characterized in that: The waterproof and breathable membrane (12) is made of polytetrafluoroethylene.

Images