Phosphoric acid semi-water slurry air cooling system and method thereof

Abstract

The invention discloses a phosphoric acid semi-hydrated slurry air cooling system and a method thereof, and relates to the technical field of phosphoric acid preparation. Comprising a slurry circulating pump, a feed port of the slurry circulating pump is connected with a discharge port in the bottom of the side wall of a reaction tank, a discharge port of the slurry circulating pump is connected with a feed port in the top of the side wall of a slurry cooler, a discharge port in the bottom of the slurry cooler is connected with a feed port of the reaction tank, and an exhaust port in the top of the slurry cooler is connected with an air inlet in the lower portion of the side wall of a demister. And an exhaust port at the top of the demister is connected with an exhaust fan. Countercurrent contact between slurry and cold air is achieved through the slurry cooler, reaction slurry is rapidly cooled and returned to the reaction tank, the cooled gas is subjected to defoaming treatment through the demister, the safety risk is low, scaling substances in the slurry cooler are few, the cleaning workload is small, and the labor intensity is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of phosphoric acid preparation, and in particular to an air cooling system and method for a phosphoric acid semi-aqueous slurry. Background Art

[0002] In the production process of wet phosphoric acid, sulfuric acid and phosphate rock are usually used as raw materials. The crushed and ground phosphate rock reacts with sulfuric acid to undergo an acidolysis reaction to generate a semi-hydrated phosphate slurry (i.e., semi-water slurry) mixed with phosphoric acid and semi-hydrated calcium sulfate crystals. The semi-water slurry is filtered through a filter to separate the solid and liquid to obtain phosphoric acid and phosphogypsum. The acidolysis of phosphate rock is an exothermic reaction. As production continues, the temperature of the reaction slurry will tend to increase. The fluctuation of the reaction temperature will make the reaction process difficult to control. At this time, the slurry needs to be cooled. In the prior art, the slurry is generally pumped into a flash chamber for flash condensation. Due to the condensation effect, the production line capacity cannot be broken through. If the capacity is to be increased, a set of flash evaporation equipment needs to be built. The investment in the original process is large and the construction is difficult, and the construction period is long. Therefore, it is urgent to develop an air cooling system and method for semi-hydrated phosphoric acid slurry. Summary of the invention

[0003] The object of the present invention is to provide a phosphoric acid semi-aqueous slurry air cooling system and method thereof, so as to solve the problem of insufficient cooling efficiency of existing equipment.

[0004] In order to solve the above-mentioned technical problems, the present invention adopts the following technical scheme: a phosphoric acid semi-aqueous slurry air cooling system, characterized in that: it includes a slurry circulation pump, the slurry circulation pump feed port is connected to the bottom discharge port of the reaction tank side wall, the slurry circulation pump discharge port is connected to the top feed port of the slurry cooler side wall, the bottom discharge port of the slurry cooler is connected to the reaction tank feed port, the top exhaust port of the slurry cooler is connected to the lower air inlet of the demister side wall, and the top exhaust port of the demister is connected to the exhaust fan.

[0005] A further technical solution is that the slurry cooler is a hollow cylinder with an exhaust port on the top, a slurry discharge port on the bottom, a slurry feed port on the top of the side wall, an air inlet on the lower part of the side wall, and an L-shaped air inlet pipe connected to the air inlet.

[0006] A further technical solution is that the slurry cooler is provided with four inclined plates staggered along the height direction.

[0007] A further technical solution is that the demister is a hollow cylinder with an exhaust port on the top, a slurry outlet at the bottom, and an air inlet at the lower part of the side wall.

[0008] A further technical solution is that the height distance between the slurry feed port and the exhaust port is more than 1 m.

[0009] The present invention also discloses a method for air cooling a semi-aqueous phosphoric acid slurry, which is characterized by comprising the following steps:

[0010] S1. When the slurry temperature in the reaction tank reaches 102 °C, start the slurry circulation pump, pump the slurry in the reaction tank into the slurry cooler, and start the air extraction fan;

[0011] S2. After the slurry contacts the cold air countercurrently in the slurry cooler, it enters the reaction tank through a pipeline, and the temperature of the cooled slurry is 100 °C;

[0012] S3. The mixed gas at the exhaust port of the slurry cooler enters the demister, and the tail gas enters the washing system after passing through the air extraction fan;

[0013] S4. A small amount of slurry in the demister flows into the reaction tank automatically through a pipeline.

[0014] A further technical solution is that the slurry feed flow rate in the slurry cooler (3) in step S1 is 150 m 3 / h, and the air volume is 4000 Nm 3 / h.

[0015] Compared with the prior art, the beneficial effects of the present invention are: to provide a phosphoric acid semi-hydrate slurry air-cooling system and method with a simple process and convenient operation, realizing the countercurrent contact between the slurry and the cold air through the slurry cooler, quickly cooling the reaction slurry and returning it to the reaction tank, performing demisting treatment on the cooled gas through the demister, having a low safety risk, less scaling in the slurry cooler, less cleaning workload, and reducing labor intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention.

[0017] Among them, 1 - slurry circulation pump, 2 - reaction tank, 3 - slurry cooler, 4 - demister, 5 - air extraction fan, 6 - L-shaped intake pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] Figure 1 Shown is: a phosphoric acid semi-hydrate slurry air-cooling system, including a slurry circulation pump 1, the inlet of the slurry circulation pump 1 is connected to the bottom discharge port on the side wall of the reaction tank 2, the outlet of the slurry circulation pump 1 is connected to the top inlet of the slurry cooler 3 on the side wall, the bottom outlet of the slurry cooler 3 is connected to the inlet of the reaction tank 2, the top exhaust port of the slurry cooler 3 is connected to the lower intake port on the side wall of the demister 4, and the top exhaust port of the demister 4 is connected to the air extraction fan 5.

[0020] The slurry cooler 3 is a hollow cylinder with a diameter of φ1800mm and a height of 8500mm. An exhaust port is provided at the top, a slurry outlet is provided at the bottom, a slurry feed port is provided at the top of the side wall, and an air inlet is provided at the lower part of the side wall. The air inlet is connected to an L-shaped air inlet pipe 6. To prevent the slurry from being sucked into the gas phase pipe, the slurry feed port provided at the top of the side wall and the top exhaust port are kept at a space of 1m. Four inclined plates are staggered in the height direction of the slurry cooler 3. The vertical distance between each inclined plate is 0.8m, and the direction is inclined downward, which is convenient for heat exchange between the slurry and the cold air, and also reduces the airflow from carrying the slurry out.

[0021] The defoamer 4 is a hollow cylinder with a diameter of φ1200 mm and a height of 2500 mm. An exhaust port is provided at the top, a slurry outlet is provided at the bottom, and an air inlet is provided at the lower part of the side wall.

[0022] The method for cooling the slurry by the air cooling system comprises the following steps:

[0023] S1. When the slurry temperature in reaction tank 2 reaches 102°C, start the slurry circulation pump 1, pump the slurry in reaction tank 2 into the slurry cooler 3, and start the exhaust fan 5; the slurry feed flow rate is 150m 3 / h, air volume is 4000Nm 3 / h;

[0024] S2. The slurry enters the reaction tank 2 through the pipeline after contacting with the cold air countercurrent in the slurry cooler 3. The slurry temperature after cooling is 100°C;

[0025] S3. The mixed gas from the exhaust port of the slurry cooler 3 enters the demister 4, and the exhaust gas enters the washing system after passing through the exhaust fan;

[0026] S4. A small amount of slurry in the demister (4) flows into the reaction tank 2 through a pipeline.

[0027] Although the present invention is described herein with reference to a number of illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise numerous other modifications and implementations that fall within the scope of the present disclosure. More specifically, within the scope of the present disclosure, drawings, and claims, a variety of variations and modifications may be made to the components or layout. In addition to variations and modifications to the components or layout, other uses will be apparent to those skilled in the art.

Claims

1. A phosphoric acid semi-aqueous slurry air cooling system, characterized in that: The invention comprises a slurry circulation pump (1), wherein the feed port of the slurry circulation pump (1) is connected to the discharge port at the bottom of the side wall of the reaction tank (2), the discharge port of the slurry circulation pump (1) is connected to the feed port at the top of the side wall of the slurry cooler (3), the discharge port at the bottom of the slurry cooler (3) is connected to the feed port of the reaction tank (2), the exhaust port at the top of the slurry cooler (3) is connected to the air inlet at the bottom of the side wall of the demister (4), and the exhaust port at the top of the demister (4) is connected to the exhaust fan (5).

2. The phosphoric acid semi-aqueous slurry air cooling system according to claim 1, characterized in that: The slurry cooler (3) is a hollow cylinder with an exhaust port at the top and a slurry discharge port at the bottom. A slurry feed port is provided at the top of the side wall and an air inlet is provided at the lower part of the side wall. The air inlet is connected to an L-shaped air inlet pipe (6).

3. The phosphoric acid semi-aqueous slurry air cooling system according to claim 2, characterized in that: Four inclined plates are arranged in an alternating manner in the height direction in the slurry cooler (3).

4. The phosphoric acid semi-aqueous slurry air cooling system according to claim 1, characterized in that: The demister (4) is a hollow cylinder, with an exhaust port at the top, a slurry outlet at the bottom, and an air inlet at the lower part of the side wall.

5. The phosphoric acid semi-aqueous slurry air cooling system according to claim 2, characterized in that: The height distance between the slurry feed port and the exhaust port is more than 1m.

6. A method for air cooling a semi-aqueous phosphoric acid slurry, characterized in that The steps include: S1. When the slurry temperature in the reaction tank (2) reaches 102°C, start the slurry circulation pump (1), pump the slurry in the reaction tank (2) into the slurry cooler (3), and start the exhaust fan (5); S2. The slurry enters the reaction tank (2) through a pipeline after contacting with the cold air countercurrent in the slurry cooler (3). The slurry temperature after cooling is 100°C; S3. The mixed gas from the exhaust port of the slurry cooler (3) enters the demister (4), and the exhaust gas enters the washing system after passing through the exhaust fan; S4. A small amount of slurry in the demister (4) flows into the reaction tank (2) through a pipeline.

7. The method for air cooling a semi-aqueous phosphoric acid slurry according to claim 6, characterized in that: The slurry feed flow rate in the slurry cooler (3) in step S1 is 150m 3 / h, air volume is 4000Nm 3 / h.

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