Emission device for phosphoric acid production tail gas environment-friendly treatment

Abstract

The utility model discloses a discharge device for phosphoric acid production tail gas environment-friendly treatment, which is characterized in that an aeration spray pipe of an aeration tower is communicated with phosphoric acid through a first pump, the aeration spray pipe is provided with a plurality of downward phosphoric acid spray heads, a phosphoric acid recovery tank positioned below the aeration spray pipe is arranged in the aeration tower, and a convection spray pipe of a neutralization tower is communicated with alkali liquor through a second pump; the convection spray pipe is provided with a plurality of downward alkali spray heads, an air inlet of the neutralizing tower is lower than the convection spray pipe and is suitable for being communicated with a hydrogen sulfide discharge outlet in the top of the aeration tower, and the neutralizing tower is provided with a downcomer collecting tank lower than the air inlet of the neutralizing tower. Compared with the prior art, hydrogen sulfide is fully separated from produced phosphoric acid, accidental hydrogen sulfide pollution in other follow-up links is avoided, and phosphoric acid tail gas is subjected to environment-friendly treatment; hydrogen sulfide is fully separated from the produced phosphoric acid, so that the subsequent phosphoric acid sewage can be discharged up to the standard.

Description

Technical Field

[0001] The utility model relates to phosphoric acid production, in particular to an emission device for environmental protection treatment of tail gas in phosphoric acid production. Background Art

[0002] In phosphoric acid production, hydrogen sulfide (H 2 S) overflows from phosphoric acid. The enterprise's tail gas treatment device only has an alkali liquor tower to carry out alkali neutralization on the overflow gas.

[0003] However, in this kind of tail gas treatment device, hydrogen sulfide in phosphoric acid is not completely separated, making it difficult to ensure the up-to-standard discharge of subsequent sewage. Content of the Utility Model

[0004] The utility model aims to solve at least one of the above-mentioned technical problems, and provides an emission device for environmental protection treatment of tail gas in phosphoric acid production, which is convenient for fully precipitating hydrogen sulfide in phosphoric acid for alkali neutralization treatment, so that the tail gas and sewage meet the discharge standards.

[0005] To achieve the above purpose, the technical scheme adopted by the utility model is as follows:

[0006] An emission device for environmental protection treatment of tail gas in phosphoric acid production includes an aeration tower and a neutralization tower. The aeration tower includes a first tower body and an aeration spray pipe arranged in the first tower body. The aeration spray pipe is connected to phosphoric acid through a first pump. The aeration spray pipe is provided with a plurality of downward phosphoric acid spray heads. A phosphoric acid recovery tank is arranged in the aeration tower below the aeration spray pipe. The neutralization tower includes a second tower body and a convection spray pipe arranged in the second tower body. The convection spray pipe is connected to alkali liquor through a second pump. The convection spray pipe is provided with a plurality of downward alkali spray heads. The air inlet of the neutralization tower is lower than the convection spray pipe and is adapted to be connected to the hydrogen sulfide discharge port at the top of the aeration tower. The neutralization tower is provided with a liquid descending and collecting tank lower than its air inlet.

[0007] Compared with the prior art, the beneficial effects of this application include: hydrogen sulfide is fully separated from the produced phosphoric acid, avoiding accidental hydrogen sulfide pollution in subsequent other links, and the environmental protection treatment of phosphoric acid tail gas ensures the up-to-standard discharge of subsequent phosphoric acid sewage.

[0008] As an improvement of the above technical scheme, the phosphoric acid spray heads and the alkali spray heads are spiral spray heads, so as to be adapted to spray liquid on the spiral filaments of the spiral spray heads and form a spiral-wound and expanding spray liquid surface.

[0009] As an improvement of the above technical scheme, the aeration tower is provided with a first acrylic window suitable for observing the phosphoric acid spray heads, and the neutralization tower is provided with a second acrylic window suitable for observing the alkali spray heads, so as to observe the liquid dispersion and atomization state of the spiral spray heads.

[0010] As an improvement to the above technical solution, a first cyclone baffle is arranged above the aeration nozzle, and a second cyclone baffle is arranged above the convection nozzle. The first cyclone baffle and the second cyclone baffle both have a plurality of spiral flow channels distributed circumferentially, and the spiral flow channels are suitable for precipitating liquid when the fog and vapor flow centrifugally.

[0011] As an improvement to the above technical solution, the air inlet of the neutralization tower is connected to the hydrogen sulfide discharge port of the aeration tower through a direct current pipe, and a hydrogen sulfide auxiliary suction port is opened on the peripheral wall of the direct current pipe.

[0012] As an improvement to the above technical solution, at least two aeration towers are provided. The aeration nozzles of at least one aeration tower are connected to industrial-grade phosphoric acid, and the aeration nozzles of at least one aeration tower are connected to food-grade phosphoric acid; the hydrogen sulfide discharge port of the aeration tower for aerating industrial-grade phosphoric acid is suitable for being connected in series to the aeration tower for aerating food-grade phosphoric acid, or the hydrogen sulfide discharge ports of both the aeration tower for aerating industrial-grade phosphoric acid and the aeration tower for aerating food-grade phosphoric acid are connected in parallel.

[0013] As an improvement to the above technical solution, the aeration tower is provided with an air make-up inlet that is lower than the aeration nozzle and higher than the phosphoric acid recovery tank.

[0014] As an improvement to the above technical solution, the convection nozzle is connected to the liquid dropping collection tank through the second pump for circulating spraying. A discharge port is arranged at the lower end of the liquid dropping collection tank, and the convection nozzle is connected to the alkali liquid supply tank through the third pump.

[0015] As an improvement to the above technical solution, a plurality of the convection nozzles are distributed at intervals in the vertical direction in the neutralization tower.

[0016] As an improvement to the above technical solution, the neutralization tower is provided with an air distribution network that is higher than its air inlet, and a hydrogen sulfide emission space is defined between the liquid level of the liquid dropping collection tank and the air distribution network. Description of the Drawings

[0017] The following further details the specific embodiments of the present invention in conjunction with the drawings, where:

[0018] Figure 1 is a layout plan of the emission device for environmental protection treatment of phosphoric acid production tail gas in an embodiment of the present invention;

[0019] Figure 2 is Figure 1 a schematic structural diagram of the aeration nozzle / convection nozzle of the emission device for environmental protection treatment of phosphoric acid production tail gas;

[0020] Figure 3 is Figure 2 a schematic working diagram of the local structure of the aeration nozzle / convection nozzle;

[0021] Figure 4 For Figure 1 show a schematic diagram of the cyclone baffle structure of the emission device for the environmental protection treatment of the tail gas in phosphoric acid production.

[0022] The attached drawings are only one specific embodiment of the present invention, and the form and structure of this specific embodiment should not limit the expansion of other embodiments.

[0023] Aeration tower 100, first tower body 110, hydrogen sulfide discharge port 111, first acrylic window 112, air supplement inlet 113, aeration spray pipe 120, phosphoric acid spray head 121, phosphoric acid recovery tank 130, first cyclone baffle 140, first filter screen 150;

[0024] Neutralization tower 200, second tower body 210, second acrylic window 211, convection spray pipe 220, alkali spray head 221, falling liquid collection tank 230, discharge port 231, second cyclone baffle 240, second filter screen 250, air distribution grid 260;

[0025] First pump 310, second pump 320;

[0026] DC pipe 400, hydrogen sulfide auxiliary suction port 410. Specific embodiments

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the attached drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] Refer to Figure 1 、 Figure 2 , the present invention provides an emission device for the environmental protection treatment of the tail gas in phosphoric acid production, including an aeration tower 100 and a neutralization tower 200. The aeration tower 100 includes a first tower body 110 and an aeration spray pipe 120 arranged inside the first tower body 110. The aeration spray pipe 120 is connected to phosphoric acid through a first pump 310. The aeration spray pipe 120 is provided with a plurality of downward phosphoric acid spray heads 121. A phosphoric acid recovery tank 130 is arranged below the aeration spray pipe 120 inside the aeration tower 100. The neutralization tower 200 includes a second tower body 210 and a convection spray pipe 220 arranged inside the second tower body 210. The convection spray pipe 220 is connected to alkali solution through a second pump 320. The convection spray pipe 220 is provided with a plurality of downward alkali spray heads 221. The air inlet of the neutralization tower 200 is lower than the convection spray pipe 220 and is adapted to be connected to the hydrogen sulfide discharge port 111 at the top of the aeration tower 100. The neutralization tower 200 is provided with a falling liquid collection tank 230 lower than its air inlet.

[0029] It is understandable that the first pump 310 and the second pump 320 are water pumps, such as common centrifugal pumps, axial flow pumps, positive displacement pumps, vane pumps, etc.

[0030] Refer to Figure 1 , the operation process of the present utility model is as follows: The produced phosphoric acid is drawn and discharged by the first pump 310, and is atomized downward through the phosphoric acid nozzle 121 of the aeration spray pipe 120. The phosphoric acid input direction is V in11 、V in12 . During the process of the phosphoric acid bursting and diverging from the liquid state to the gaseous state, hydrogen sulfide therein is precipitated;

[0031] The phosphoric acid mist with precipitated hydrogen sulfide is settled and recovered. The phosphoric acid recovery direction is V out21 、V out22 . The precipitated hydrogen sulfide overflows upward from the aeration tower 100. The hydrogen sulfide overflow direction of the aeration tower 100 is V 31 、V 32 ;

[0032] In the neutralization tower 200, the alkali nozzle 221 of the convection spray pipe 220 sprays atomized alkali liquor downward. Refer to the V in41 direction. An alkali mist space is formed below the convection spray pipe 220. After the hydrogen sulfide overflowing from the aeration tower 100 is introduced into the neutralization tower 200, it convects upward and sinks into the alkali mist. The hydrogen sulfide reacts with the alkali to eliminate the hydrogen sulfide. The alkali liquor can be caustic soda, ammonia water, NaHCO 3 ;

[0033] Among them, according to the fugacity, buoyancy of the gas and the negative pressure formed by the gas elimination in the neutralization tower 200, the hydrogen sulfide in the aeration tower 100 effectively flows to the neutralization tower 200, and an air flow is formed from the aeration tower 100 to the neutralization tower 200. During the stable treatment of the tail gas (that is, during the continuous aeration and neutralization process), the air supply port at the lower end of the aeration tower 100 is opened to ensure the stable and continuous air flow. The mist in the aeration tower 100 plays a certain blocking effect, which is convenient for forming a small degree of negative pressure after eliminating hydrogen sulfide outward above the aeration spray pipe 120. This small degree of negative pressure is conducive to the precipitation of hydrogen sulfide from the phosphoric acid mist.

[0034] Compared with the prior art, the beneficial effects of the present application include: The produced phosphoric acid is fully separated from hydrogen sulfide, avoiding accidental hydrogen sulfide pollution in subsequent other links, and environmentally friendly treatment of phosphoric acid tail gas to ensure the up-to-standard discharge of subsequent phosphoric acid sewage.

[0035] Refer to Figures 1 to 3 , in some embodiments of the present utility model, the phosphoric acid nozzle 121 and the alkali nozzle 221 are spiral nozzles, which are adapted to the spiral filaments of the object liquid spraying spiral nozzles, and form a spiral-wound and expanding spray liquid surface. The phosphoric acid bursts out hydrogen sulfide upon impact, and the hydrogen sulfide is further fully precipitated in the divergent spray liquid surface / spray mist surface.

[0036] Reference Figure 1 In some embodiments of the present utility model, the aeration tower 100 is provided with a first acrylic window 112 suitable for observing the phosphoric acid nozzle 121, and the neutralization tower 200 is provided with a second acrylic window 211 suitable for observing the alkali nozzle 221, so as to observe the liquid dispersion and atomization state of the spiral nozzle, and adjust the power of the first pump 310 and the second pump 320, or adjust the speed control valve on the pipeline.

[0037] Reference Figure 1 、 Figure 4 In some embodiments of the present utility model, a first cyclone baffle 140 is arranged above the aeration nozzle pipe 120, and a second cyclone baffle 240 is arranged above the convection nozzle pipe 220. Both the first cyclone baffle 140 and the second cyclone baffle 240 are provided with a plurality of spiral flow channels distributed circumferentially. The spiral flow channels are suitable for precipitating liquid when the fog and vapor flow centrifugally. The liquefied phosphoric acid / alkali liquid / neutralization liquid flows along the cyclone separator to the inner wall of the tower, and then slides into the recovery tank / collection tank at the bottom of the tower.

[0038] Reference Figure 1 In some embodiments of the present utility model, the air inlet of the neutralization tower 200 is connected to the hydrogen sulfide discharge port 111 of the aeration tower 100 through a direct current pipe 400, as shown in directions V 32 、V 34 A hydrogen sulfide auxiliary suction port 410 is opened on the peripheral wall of the direct current pipe 400, as shown in direction V 33 The ready-made hydrogen sulfide captured in phosphoric acid production is suitable for being put into the neutralization tower 200 through the hydrogen sulfide auxiliary suction port 410. The direct current low-pressure effect of the direct current pipe 400 is suitable for providing suction power. In addition, the negative pressure formed by the degassing of the neutralization tower 200 also provides suction power.

[0039] Reference Figure 1 In some embodiments of the present utility model, at least two aeration towers 100 are provided. The aeration nozzle pipes 120 of at least one aeration tower 100 are connected to industrial-grade phosphoric acid, and the aeration nozzle pipes 120 of at least one aeration tower 100 are connected to food-grade phosphoric acid; the hydrogen sulfide discharge port 111 of the aeration tower 100 for aerating industrial-grade phosphoric acid is suitable for being connected in series to the aeration tower 100 for aerating food-grade phosphoric acid, or the hydrogen sulfide discharge ports 111 of both the aeration tower 100 for aerating industrial-grade phosphoric acid and the aeration tower 100 for aerating food-grade phosphoric acid are connected in parallel.

[0040] Reference Figure 1 In some embodiments of the present utility model, the air supplement inlet 113 lower than the aeration nozzle pipe 120 and higher than the phosphoric acid recovery tank 130 is arranged on the aeration tower 100 to prevent the tower from being deformed due to inter-tower interlocking negative pressure during aeration; when the aeration tower 100 is supplemented with air, the aeration nozzle pipe 120 stably sprays phosphoric acid with the power of the first pump 310 to form stable water mist and vapor.

[0041] Reference Figure 1 In some embodiments of the present utility model, the convection spray pipe 220 communicates with the liquid drainage collection tank 230 through the second pump 320, see direction V 51 for circulating spraying. A drain port 231 is provided at the lower end of the liquid drainage collection tank 230, and the convection spray pipe 220 communicates with the lye supply tank through the third pump, see direction V 52 . After each new supply of lye is used for a certain period of time, or when the pH value of the reused lye is lower than a certain value, the liquid drainage collection tank 230 discharges the old liquid, and the convection spray pipe 220 supplies new lye through the third pump

[0042] Preferably, the liquid drainage collection tank 230 is provided with a digital pH sensor. Based on the pH value displayed by the pH sensor, it is determined whether the liquid drainage collection tank 230 should discharge, and whether the convection spray pipe 220 should supply new lye. The pH sensor is a well-known sensor for measuring the pH value of a liquid. It is a sensor that detects the hydrogen ion concentration in the measured substance and converts it into a corresponding available output signal. It is usually composed of a chemical part and a signal transmission part, and is often used for industrial measurement of substances such as solutions and water

[0043] Reference Figure 1 Better, a plurality of convection spray pipes 220 are spaced along the vertical direction inside the neutralization tower 200, facilitating the reused lye to fully play the role of degassing and neutralization

[0044] Reference Figure 1 In some embodiments of the present utility model, a first filter screen 150 is provided between the phosphoric acid recovery tank 130 and the aeration spray pipe 120, and the slag that may be mixed in the original phosphoric acid can be filtered out, and the recovered phosphoric acid is cleaner

[0045] Reference Figure 1 Furthermore, the air inlet 113 is higher than the first filter screen 150 to prevent air dust from mixing into the phosphoric acid

[0046] Reference Figure 1 In some embodiments of the present utility model, the neutralization tower 200 is provided with an air equalizing net 260 higher than its air inlet. A hydrogen sulfide divergence space is defined between the liquid level of the liquid drainage collection tank 230 and the air equalizing net 260. The hydrogen sulfide after divergence and homogenization rushes upward to the mist below the convection spray pipe 220, and the hydrogen sulfide comes into full and effective contact with the lye mist sprayed by the convection spray pipe 220, effectively eliminating hydrogen sulfide

[0047] Reference Figure 1 In some embodiments of the present utility model, a second filter screen 250 is provided between the air inlet of the neutralization tower 200 and the liquid drainage collection tank 230

[0048] Reference Figure 1 In some embodiments of the present utility model, a sampling port is provided on the exhaust chimney of the neutralization tower 200

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the technical solutions of the present invention.

Claims

1. A discharge device for environmentally friendly treatment of tail gas from phosphoric acid production, characterized in that: include: an aeration tower, comprising a first tower body and an aeration nozzle disposed in the first tower body, the aeration nozzle being connected to phosphoric acid via a first pump, the aeration nozzle being provided with a plurality of downward phosphoric acid nozzles, and the aeration tower being provided with a phosphoric acid recovery tank located below the aeration nozzle; The neutralization tower comprises a second tower body and a convection nozzle arranged in the second tower body, the convection nozzle is connected to the alkali solution through a second pump, the convection nozzle is provided with a plurality of downward alkali nozzles, the air inlet of the neutralization tower is lower than the convection nozzle, and is suitable for connecting to the hydrogen sulfide discharge port at the top of the aeration tower, and the neutralization tower is provided with a downcomer collecting tank lower than its air inlet.

2. The discharge device for environmentally friendly treatment of tail gas from phosphoric acid production according to claim 1, characterized in that: The phosphoric acid nozzle and the alkali nozzle are spiral nozzles, which are suitable for spraying liquid on the spiral winding wires of the spiral nozzles to form a spirally wound and expanded liquid spraying surface.

3. The discharge device for environmentally friendly treatment of tail gas from phosphoric acid production according to claim 2, characterized in that: The aeration tower is provided with a first acrylic window suitable for observing the phosphoric acid nozzle, and the neutralization tower is provided with a second acrylic window suitable for observing the alkali nozzle, so as to observe the liquid dispersion and atomization state of the spiral nozzle.

4. The discharge device for environmentally friendly treatment of tail gas from phosphoric acid production according to claim 1, characterized in that: A first cyclone baffle is arranged above the aeration nozzle, and a second cyclone baffle is arranged above the convection nozzle. Both the first cyclone baffle and the second cyclone baffle have a plurality of spiral flow channels distributed along the circumference, and the spiral flow channels are suitable for precipitating liquid when mist flows centrifugally.

5. The discharge device for environmentally friendly treatment of tail gas from phosphoric acid production according to any one of claims 1 to 4, characterized in that: The air inlet of the neutralization tower is connected to the hydrogen sulfide discharge port of the aeration tower through a direct current pipe, and a hydrogen sulfide secondary suction port is provided on the peripheral wall of the direct current pipe.

6. The emission device for environmentally friendly treatment of tail gas from phosphoric acid production according to claim 5, characterized in that: At least two aeration towers are provided, the aeration nozzle of at least one aeration tower is connected to industrial-grade phosphoric acid, and the aeration nozzle of at least one aeration tower is connected to food-grade phosphoric acid; the hydrogen sulfide discharge port of the aeration tower aerating industrial-grade phosphoric acid is suitable for being connected in series with the aeration tower aerating food-grade phosphoric acid, or the hydrogen sulfide discharge ports of the aeration tower aerating industrial-grade phosphoric acid and the aeration tower aerating food-grade phosphoric acid are connected in parallel.

7. The emission device for environmentally friendly treatment of tail gas from phosphoric acid production according to claim 5, characterized in that: The aeration tower is provided with an air replenishing inlet which is lower than the aeration nozzle and higher than the phosphoric acid recovery tank.

8. The discharge device for environmentally friendly treatment of tail gas from phosphoric acid production according to any one of claims 1 to 4, characterized in that: The convection nozzle is connected to the downcomer collecting tank through the second pump for circulating spraying. A discharge port is provided at the lower end of the downcomer collecting tank, and the convection nozzle is connected to the alkali solution supply tank through the third pump.

9. The emission device for environmentally friendly treatment of tail gas from phosphoric acid production according to claim 8, characterized in that: A plurality of the convection nozzles are distributed in the neutralization tower at intervals along the vertical direction.

10. The emission device for environmentally friendly treatment of tail gas from phosphoric acid production according to any one of claims 1 to 4, characterized in that: The neutralization tower is provided with a gas-equalizing net higher than its gas inlet, and a hydrogen sulfide dispersing space is defined between the liquid surface of the downcomer collecting tank and the gas-equalizing net.

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