Absorption device suitable for wet-process phosphoric acid production

Abstract

The invention relates to an absorption device suitable for wet-process phosphoric acid production, which comprises a gas and liquid inlet chamber, a gas-liquid mixing chamber and a gas-liquid separation tank, the gas and liquid inlet chamber is vertically cylindrical, the upper end of the gas and liquid inlet chamber is closed, the lower end of the gas and liquid inlet chamber is open, and the side wall of the gas and liquid inlet chamber is provided with a gas inlet pipe and a liquid inlet pipe which are communicated with the inside of the gas and liquid inlet chamber; the upper end and the lower end of the gas-liquid mixing chamber are open cylinders; the upper end surface of the gas-liquid separation tank is provided with an inlet pipe and a gas outlet pipe which are communicated with the interior of the gas-liquid separation tank; the lower end surface of the gas-liquid separation tank is provided with a liquid outlet pipe; the upper end of the gas-liquid mixing chamber is connected with the lower end of the gas-liquid inlet chamber, and the lower end of the gas-liquid mixing chamber is communicated with the inlet pipe; the device further comprises a partition plate and a spraying cup. The partition plate is in a flat plate shape and is arranged at the joint of the gas-liquid mixing chamber and the gas and liquid inlet chamber; a through-hole-shaped mounting hole is formed in the partition plate; the spray cup is a conical barrel with a large upper part and a small lower part and two open ends, and is clamped on the mounting hole in a penetrating manner, so that the flow velocity of gas-liquid mixed liquid is increased, and the scaling of the absorption device is reduced.

Description

Technical Field

[0001] The invention relates to a chemical production device, in particular to a device for absorbing tail gas, specifically to an absorption device suitable for wet-process phosphoric acid production. Background Art

[0002] Phosphoric acid is an important intermediate product in the phosphate fertilizer industry. It can be further processed to derive many types of phosphate fertilizers and industrial phosphates. At present, phosphoric acid is mainly produced by wet phosphoric acid, that is, phosphoric acid produced by decomposing phosphate rock with sulfuric acid. The production processes of wet phosphoric acid include dihydrate process, semi-hydrate process, semi-hydrate-dihydrate process and other processes. Among them, in the dihydrate process, the fluorine content in the tail gas escaping from the reaction tank is very small. However, in the semi-hydrate process and semi-hydrate-dihydrate process, due to different reaction conditions, the fluorine in the overflowed gas is mainly SiF 4 Therefore, the amount of fluorine released in the tail gas can usually reach 40% to 60% of the total fluorine in the phosphate rock, so it is absolutely necessary to absorb and utilize it.

[0003] At present, the tail gas absorption device mainly adopts the Venturi absorption device. The device is mainly composed of a contraction tube, a throat, a diffusion tube, etc. Among them, the contraction angle of the contraction tube is usually 15°~25°, and the diffusion angle of the diffusion tube is usually 5°~7°. The size of the entire Venturi absorption device is relatively long, resulting in greater resistance, and it is generally driven by gas. Due to the high dispersion of liquid and gas, a demisting device is often connected to the back of the Venturi absorption device. However, the amount of fluorine released in the wet phosphoric acid production process is large and the concentration is high, resulting in a large amount of silica gel precipitation, which makes the Venturi absorption device easily blocked by silica gel. Moreover, the Venturi absorption device is not easy to disassemble and clean, and the fluid resistance is large, which has an adverse effect on production.

[0004] Therefore, it is urgently needed to be improved in order to better meet production needs. Summary of the invention

[0005] The purpose of the present invention is to provide an absorption device suitable for wet phosphoric acid production in view of the shortcomings of the prior art, which can wash the tail gas of phosphoric acid production and absorb fluoride in the tail gas, reduce scaling of the absorption device and increase the operating rate.

[0006] The technical solution of the present invention is:

[0007] An absorption device suitable for wet-process phosphoric acid production, comprising an air inlet and liquid inlet chamber, a gas-liquid mixing chamber and a gas-liquid separation tank, wherein the air inlet and liquid inlet chamber is a vertical cylindrical chamber, the upper end of which is closed and the lower end is open, and the side wall of the chamber is provided with an air inlet pipe and a liquid inlet pipe communicating with the interior thereof; the gas-liquid mixing chamber is a cylindrical chamber with both upper and lower ends open; the gas-liquid separation tank is a circular tank, the upper end surface of which is provided with an inlet pipe and an air outlet pipe communicating with the interior thereof, and the lower end surface of the gas-liquid mixing chamber is provided with a liquid outlet pipe; the upper end of the gas-liquid mixing chamber is connected to the lower end of the air inlet and liquid inlet chamber, and the lower end of the gas-liquid mixing chamber is connected to the inlet pipe;

[0008] It also includes a partition plate and a spray cup; the partition plate is in the shape of a flat plate, arranged at the connection between the gas-liquid mixing chamber and the air and liquid inlet chamber, and closes the lower end of the air and liquid inlet chamber and the upper end of the gas-liquid mixing chamber; a through-hole-shaped mounting hole is provided on the partition plate; the spray cup is a conical cylinder with a larger upper part and a smaller lower part and open at both ends, and is penetrated and sealed and clamped on the mounting hole.

[0009] Furthermore, the cross section of the air and liquid inlet chamber is larger than the cross section of the gas-liquid mixing chamber; the ratio of the cross section area of ​​the gas-liquid mixing chamber to the area of ​​the lower port of the spray cup is 5 to 9:1.

[0010] Furthermore, an openable inspection and cleaning door is provided at the upper end of the air and liquid inlet chamber.

[0011] Furthermore, the ratio of the height of the gas-liquid mixing chamber to the height of the gas and liquid inlet chamber is 1 to 2:1.

[0012] Furthermore, the air inlet pipe is located at the upper part of the air inlet and liquid inlet chamber; and the liquid inlet pipe is located at the lower part of the air inlet and liquid inlet chamber.

[0013] Furthermore, the spray cup includes an upper section and a lower section; the upper section and the lower section are both conical cylindrical; the taper of the upper section is greater than the taper of the lower end; the connection between the upper section and the lower section is flush with the upper edge of the mounting hole; the height of the upper section is ≤ the distance between the liquid inlet pipe and the partition plate; the ratio of the height of the upper section to the height of the lower section is 1 to 4:1.

[0014] Furthermore, the mounting hole is a conical hole that is larger at the top and smaller at the bottom, and its taper is the same as that of the lower section, so that the lower section can fit tightly with the mounting hole; the mounting hole is located in the center of the partition plate.

[0015] Furthermore, it also includes a reinforcing plate; the reinforcing plate is in the shape of a flat plate, stacked on the partition plate, and provided with a through-hole-shaped opening; the size of the opening is adapted to the lower part of the upper section so that the upper section can be snapped onto the opening.

[0016] Furthermore, the inlet pipe extends into the interior of the gas-liquid separation tank, and the ratio of the length of the extending portion to its inner diameter is 1 to 2:1.

[0017] Furthermore, the ratio of the inner diameter of the air outlet pipe to the inner diameter of the air inlet pipe is 1:1.

[0018] Beneficial effects of the present invention:

[0019] The invention has reasonable design, simple structure, easy installation and maintenance, can increase the flow rate of gas-liquid mixture through the spray cup, and reduce pressure drop at the same time, wash the tail gas in the production of wet phosphoric acid, absorb fluoride in the tail gas, reduce scaling, and increase the operating rate. Moreover, the spray cup is easy to disassemble and clean, which fully meets the production needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention.

[0021] Among them, 1-liquid outlet pipe, 2-gas-liquid separation tank, 3-gas-liquid mixing chamber, 4-air and liquid inlet chamber, 5-liquid inlet pipe, 6-inspection and cleaning door, 7-air inlet pipe, 8-spray cup, 9-partition plate, 10-inlet pipe, 11-air outlet pipe, 12-reinforcement plate. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] like Figure 1 shown.

[0024] An absorption device suitable for wet-process phosphoric acid production comprises an air and liquid inlet chamber 4, a gas-liquid mixing chamber 3 and a gas-liquid separation tank 2.

[0025] The air inlet and liquid inlet chamber 4 is a vertical cylindrical shape, and its upper and lower ends are open, and an inspection and cleaning door 6 is set at its upper end to close the port. The inspection and cleaning door 6 is connected to the upper port of the air inlet and liquid inlet chamber 4 through a flange, which is convenient to open. At the same time, an air inlet pipe 7 is provided on the upper part of the side wall of the air inlet and liquid inlet chamber 4, and a liquid inlet pipe 5 is provided on the lower part of the side wall. The air inlet pipe 7 and the liquid inlet pipe 5 are both connected to the interior of the air inlet and liquid inlet chamber 4, and are respectively connected to the production line through flanges, so as to introduce the tail gas and absorption liquid from the boundary area into the air inlet and liquid inlet chamber respectively.

[0026] The gas-liquid mixing chamber 3 is a cylindrical shape with both upper and lower ends open, and its upper end is connected to the lower end of the air inlet and liquid inlet chamber 4 through a flange. The cross-section of the gas-liquid mixing chamber 3 is smaller than the cross-section of the air inlet and liquid inlet chamber 4, and a partition plate 9 is provided at the connection between the two. The partition plate 9 is in the shape of a flat plate, which closes the lower end of the air inlet and liquid inlet chamber 4 and the upper end of the gas-liquid mixing chamber 3. At the same time, a through-hole-shaped mounting hole is provided in the center position of the partition plate 9, and a spray cup 8 is provided on the mounting hole. Preferably, the ratio of the height of the gas-liquid mixing chamber to the height of the air inlet and liquid inlet chamber is 1 to 2:1.

[0027] The spray cup 8 is a tapered cylinder that is larger at the top and smaller at the bottom and open at both ends, including an upper section and a lower section. Both the upper section and the lower section are tapered cylinders. However, the taper of the upper section is greater than the taper of the lower end, and the ratio of the height of the upper section to the height of the lower section is 1 to 4:1. At the same time, the height of the upper section is ≤ the distance between the liquid inlet pipe and the partition plate. Preferably, the ratio of the cross-sectional area of ​​the gas-liquid mixing chamber to the area of ​​the lower port of the spray cup is 5 to 9:1.

[0028] The mounting hole is a tapered hole that is larger at the top and smaller at the bottom, and its taper is the same as that of the lower section, so that the lower section can fit tightly with the mounting hole, facilitating the sealing clamping of the spray cup 8 on the partition plate 9. Moreover, the connection between the upper section and the lower section is flush with the upper edge of the mounting hole, so that the upper end and the lower end of the spray cup 8 are respectively located in the gas and liquid inlet chamber 4 and the gas-liquid mixing chamber 3.

[0029] The gas-liquid separation tank 2 is in the shape of a circular tank, and its upper end face is provided with an inlet pipe 10 and an air outlet pipe 11 which are connected to the interior thereof, and its lower end face is a cone with a larger upper portion and a smaller lower portion, and a liquid outlet pipe 1 is provided at the lowest end. The inlet pipe 10 is connected and communicated with the upper end of the gas-liquid mixing chamber 3 through a flange, so that the mixed liquid in the gas-liquid mixing chamber flows into the gas-liquid separation tank for gas-liquid separation, and then the separated gas and liquid are discharged from the air outlet pipe and the liquid outlet pipe respectively. Preferably, the inlet pipe 10 extends into the interior of the gas-liquid separation tank, and the ratio of the length of the extended portion to its inner diameter is 1 to 2:1, to ensure that the mixed liquid can stably flow into the gas-liquid separation tank. At the same time, the ratio of the inner diameter of the air outlet pipe 11 to the inner diameter of the air inlet pipe 7 is 1:1, which meets production requirements.

[0030] Furthermore, a reinforcing plate 12 is included. The reinforcing plate 12 is in the shape of a flat plate, and its area is smaller than that of the partition plate 9, and its thickness is equivalent to that of the partition plate 9. A through-hole-shaped opening is provided in the center thereof, and the size of the opening is adapted to the lower portion of the upper section of the spray cup 8. The reinforcing plate 12 is stacked on the partition plate 9, and the upper section of the spray cup is clamped on the opening, thereby improving the stability of the spray cup.

[0031] The working process of the present invention is:

[0032] Exhaust gas from the boundary area (containing 7.5g / m 3 , temperature 70℃) enters the air inlet and liquid inlet chamber from the air inlet. The absorption liquid from the boundary zone (containing H 2 SiF 6 The tail gas and the absorption liquid are mixed, washed and absorbed in the gas and liquid inlet chamber. Then, the gas-liquid mixture flows into the gas-liquid mixing chamber through the spray cup, and is mixed, washed and absorbed again in the spray cup, and flows out of the spray cup at a gas flow rate of 30m / s. The gas-liquid mixture entering the gas-liquid mixing chamber continues to be mixed, washed and absorbed, and enters the gas-liquid separation tank through the inlet pipe of the gas-liquid separation tank. In the gas-liquid separation tank 2, the fluorine content of the tail gas is reduced to 0.3g / m 3 The temperature drops to 55°C and flows upward, out of the gas outlet pipe of the gas-liquid separation tank to the boundary area. 2 SiF 6 The mass concentration rises to 20% and flows downward, out of the liquid outlet pipe of the gas-liquid separation tank to the boundary area, and can be used to produce aluminum fluoride, sodium aluminofluoride, and anhydrous hydrogen fluoride, turning waste into treasure.

[0033] The air flow velocity of the bottom port of the spray cup of the present invention is generally 25m / s to 30m / s, and the air flow velocity of the throat of the existing Venturi absorption device is generally 18m / s to 38m / s, and the two are basically equivalent. However, the pressure drop of the present invention is 1765Pa to 1961Pa, which is lower than the pressure drop of the Venturi absorption device (2666Pa to 3332Pa), while the washing and absorption effects of the two are the same, both of which can reach 95% to 96%. Moreover, the air inlet and liquid inlet chamber of the present invention and the partition plate, the partition plate and the gas-liquid mixing chamber, and the gas-liquid mixing chamber and the gas-liquid separation tank are all flange-connected, which is easy to install and disassemble, and convenient for maintenance. At the same time, the spray cup and the partition plate are movably connected, which is easy to take out and clean, and convenient to use.

[0034] The operating effect of the present invention is shown in Table 1.

[0035] Table 1 Operation results of 1000 cubic meters / hour fluorine-containing tail gas

[0036] Imported exhaust gas volume Fluoride concentration Exhaust volume Fluoride concentration <![CDATA[1026m 3 / h]]> <![CDATA[7.5g / m 3 ]]> <![CDATA[981m 3 / h]]> <![CDATA[0.3g / m 3 ]]> Inlet absorption liquid volume Fluorosilicic acid concentration Outlet absorption liquid volume Fluorosilicic acid concentration 1539kg / h 19.4％ 1546kg / h 20％

[0037] The parts not involved in the present invention are the same as the prior art or can be implemented by using the prior art.

Claims

1. An absorption device suitable for wet-process phosphoric acid production, comprising a gas and liquid inlet chamber, a gas-liquid mixing chamber and a gas-liquid separation tank, characterized in that: The air inlet and liquid inlet chamber is a vertical cylindrical shape, the upper end of which is closed and the lower end is open, and the side wall thereof is provided with an air inlet pipe and a liquid inlet pipe which are connected with the interior thereof; the gas-liquid mixing chamber is a cylindrical shape with both upper and lower ends open; the gas-liquid separation tank is a circular tank shape, the upper end surface of which is provided with an inlet pipe and an air outlet pipe which are connected with the interior thereof, and the lower end surface of which is provided with a liquid outlet pipe; the upper end of the gas-liquid mixing chamber is connected with the lower end of the air inlet and liquid inlet chamber, and the lower end thereof is connected with the inlet pipe; It also includes a partition plate and a spray cup; the partition plate is in the shape of a flat plate, arranged at the connection between the gas-liquid mixing chamber and the air and liquid inlet chamber, and closes the lower end of the air and liquid inlet chamber and the upper end of the gas-liquid mixing chamber; a through-hole-shaped mounting hole is provided on the partition plate; the spray cup is a conical cylinder with a larger upper part and a smaller lower part and open at both ends, and is penetrated and sealed and clamped on the mounting hole.

2. The absorption device suitable for wet process phosphoric acid production according to claim 1, characterized in that: The cross section of the air and liquid inlet chamber is larger than the cross section of the gas-liquid mixing chamber; the ratio of the cross section area of ​​the gas-liquid mixing chamber to the area of ​​the lower port of the spray cup is 5 to 9:

1.

3. The absorption device suitable for wet process phosphoric acid production according to claim 1, characterized in that: An openable inspection and cleaning door is provided at the upper end of the air and liquid inlet chamber.

4. The absorption device suitable for wet process phosphoric acid production according to claim 1, characterized in that: The ratio of the height of the gas-liquid mixing chamber to the height of the gas-intake and liquid-intake chamber is 1 to 2:

1.

5. The absorption device suitable for wet process phosphoric acid production according to claim 1, characterized in that: The air inlet pipe is located at the upper part of the air inlet and liquid inlet chamber; the liquid inlet pipe is located at the lower part of the air inlet and liquid inlet chamber.

6. The absorption device suitable for wet process phosphoric acid production according to claim 1, characterized in that: The spray cup includes an upper section and a lower section; both the upper section and the lower section are conical cylindrical; the taper of the upper section is greater than the taper of the lower end; the connection between the upper section and the lower section is flush with the upper edge of the mounting hole; the height of the upper section is ≤ the distance between the liquid inlet pipe and the partition plate; the ratio of the height of the upper section to the height of the lower section is 1 to 4:

1.

7. The absorption device suitable for wet process phosphoric acid production according to claim 6, characterized in that: The mounting hole is a tapered hole that is larger at the top and smaller at the bottom, and its taper is the same as that of the lower section, so that the lower section can fit tightly with the mounting hole; the mounting hole is located in the center of the partition plate.

8. The absorption device suitable for wet process phosphoric acid production according to claim 6, characterized in that: It also includes a reinforcing plate; the reinforcing plate is in the shape of a flat plate, stacked on the partition plate, and provided with a through-hole-shaped opening; the size of the opening is adapted to the lower part of the upper section so that the upper section can be snapped onto the opening.

9. The absorption device suitable for wet process phosphoric acid production according to claim 1, characterized in that: The inlet pipe extends into the interior of the gas-liquid separation tank, and the ratio of the length of the extending portion to its inner diameter is 1 to 2:

1.

10. The absorption device suitable for wet process phosphoric acid production according to claim 1, characterized in that: The ratio of the inner diameter of the air outlet pipe to the inner diameter of the air inlet pipe is 1:1.

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