A food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system

Abstract

This utility model discloses a comprehensive utilization system for food-grade diammonium hydrogen phosphate tail gas. The diammonium hydrogen phosphate tail gas enters the tail gas treatment device through the tail gas inlet pipe. The ammonia in the diammonium hydrogen phosphate tail gas is sprayed by food-grade concentrated phosphoric acid in the spray mechanism. The concentrated phosphoric acid and ammonia undergo an acid-base neutralization reaction. The reaction is rapid, and the large amount of heat released can remove the moisture in the concentrated phosphoric acid. After the tail gas enters the sleeve through the baffle mechanism, it is discharged through the tail gas outlet pipe. Clean water flows through the descaling mechanism to spray and descale the tail gas pipe at regular intervals. The concentrated phosphoric acid reacts with ammonia and flows back to the mixed acid storage tank. Part of the mixed acid storage tank is sprayed through the first external discharge pipe and the spray mechanism for recycling. The other part flows into the reaction vessel through the second external discharge pipe when the concentration of the mixed acid storage tank reaches pH 3.5 to continue to react with the ammonia introduced through the ammonia inlet pipe to generate diammonium hydrogen phosphate. The reaction reaches its endpoint at pH 8.

Description

Technical Field

[0001] This utility model belongs to the field of diammonium hydrogen phosphate preparation technology, specifically relating to a comprehensive utilization system for food-grade diammonium hydrogen phosphate tail gas. Background Technology

[0002] Treatment of diammonium phosphate (DAP) tail gas has always been a challenge in the production of industrial and food-grade DAP. The tail gas mainly contains unneutralized ammonia, which, when directly emitted, impacts the environment. Using hydrochloric acid absorption results in low-value ammonium chloride byproducts, increasing production costs. Using this method, ammonia consumption exceeds 300 kg / t per ton of product, and most current tail gas treatment methods require multiple stages of processing, are cumbersome, and cannot be widely applied in production. To reduce liquid ammonia consumption and minimize the environmental impact of liquid ammonia emissions, a method was developed that uses treated food-grade concentrated phosphoric acid to absorb liquid ammonia in the tail gas. When the concentration approaches the crystallization concentration, it is pumped into a reaction vessel to continue reacting with the ammonia gas introduced into the vessel. A dedicated spray absorption tail gas treatment system and an interlocking automated batching system were independently designed to achieve an ammonia concentration in the tail gas at the ppm level, meeting environmental protection requirements. The consumption per ton of product reaches close to the theoretical value of 258 kg / t, significantly reducing product costs. This method offers significant economic and environmental benefits, maximizing the comprehensive recycling of ammonia gas and turning waste into treasure. Utility Model Content

[0003] The purpose of this invention is to solve the problems of existing technology and provide a comprehensive utilization system for food-grade diammonium hydrogen phosphate tail gas. The diammonium hydrogen phosphate tail gas enters the tail gas treatment device through the tail gas inlet pipe. The ammonia in the diammonium hydrogen phosphate tail gas is sprayed by food-grade concentrated phosphoric acid in the spray mechanism. The concentrated phosphoric acid and ammonia undergo an acid-base neutralization reaction. The reaction is rapid, and the large amount of heat released can remove the moisture in the concentrated phosphoric acid. After passing through the baffle mechanism and the sleeve, the tail gas is discharged through the tail gas outlet pipe. Clean water flows through the descaling mechanism to spray and descale the tail gas pipe at regular intervals (removing ammonium phosphate crystals and other dirt around the pipe to prevent pipe blockage). The concentrated phosphoric acid reacts with ammonia and flows back to the mixed acid storage tank. Part of the mixed acid storage tank is sprayed through the first external discharge pipe and the spray mechanism for recycling. The other part flows into the reaction vessel through the second external discharge pipe when the concentration in the mixed acid storage tank reaches pH 3.5 to continue reacting with the ammonia introduced through the ammonia inlet pipe to generate diammonium phosphate. The reaction reaches its endpoint at pH 8.

[0004] This utility model is achieved through the following technical solution:

[0005] A comprehensive utilization system for food-grade diammonium hydrogen phosphate tail gas includes a tail gas treatment device, a mixed acid storage tank, and a reaction vessel. The tail gas treatment device is equipped with a spray mechanism, a baffle mechanism, and a descaling mechanism arranged sequentially from top to bottom. The descaling mechanism is connected to a clean water inlet pipe. A sleeve is installed outside the descaling mechanism, and a tail gas outlet pipe is installed inside the sleeve. An air inlet and a discharge outlet are respectively provided at the upper and lower ends of the tail gas treatment device. The lower part of the tail gas treatment device is connected to the mixed acid storage tank, and the discharge outlet is located inside the mixed acid storage tank. The mixed acid storage tank is equipped with a food-grade concentrated phosphoric acid inlet pipe, a first discharge pipe, and a second discharge pipe. The first discharge pipe is connected to the inlet end of the spray mechanism, and the second discharge pipe is connected to the reaction vessel. The reaction vessel is also equipped with an ammonia inlet pipe and an outlet pipe. The outlet pipe is connected to the tail gas inlet pipe and then to the air inlet.

[0006] Preferably, the spraying mechanism includes a first spraying disc, a spraying inlet pipe, and a second spraying disc. The spraying inlet pipe is connected to the first spraying disc and the second spraying disc. The first spraying disc is provided with a plurality of first nozzles, and the second spraying disc is provided with a plurality of second nozzles.

[0007] Preferably, the partition mechanism includes multiple downwardly arranged partitions, one end of which is connected to the inner wall of the exhaust gas treatment device, and a gap is provided between two adjacent partitions.

[0008] Preferably, the descaling mechanism includes a third spray plate and a plurality of third nozzles disposed at the lower end of the third spray plate.

[0009] Preferably, an exhaust fan is installed on the exhaust pipe.

[0010] Preferably, the mixed acid storage tank is equipped with a stirring device.

[0011] Preferably, the food-grade concentrated phosphoric acid inlet pipe is equipped with a food-grade concentrated phosphoric acid pump and a food-grade concentrated phosphoric acid storage tank.

[0012] Preferably, the clean water inlet pipe is equipped with a clean water pump and a clean water storage tank.

[0013] Preferably, the water inlet pipe, the food-grade concentrated phosphoric acid inlet pipe, the first outlet pipe, the second outlet pipe, the gas outlet pipe, and the exhaust gas inlet pipe are all equipped with feed valves.

[0014] Preferably, the mixed acid storage tank is equipped with a level gauge and a first pH meter, and the reaction vessel is equipped with a second pH meter.

[0015] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0016] I. This utility model provides a comprehensive utilization system for food-grade diammonium hydrogen phosphate tail gas. The diammonium hydrogen phosphate tail gas enters the tail gas treatment device through the tail gas inlet pipe. The ammonia in the diammonium hydrogen phosphate tail gas is sprayed by food-grade concentrated phosphoric acid in the spray mechanism. The concentrated phosphoric acid and ammonia undergo an acid-base neutralization reaction. The reaction is rapid, and the large amount of heat released can remove the moisture in the concentrated phosphoric acid. After the tail gas passes through the baffle mechanism and the sleeve, clean water flows through the descaling mechanism to spray and descale the tail gas pipeline at regular intervals (removing ammonium phosphate crystals and other dirt around the pipeline to prevent blockage. There is a backflow valve on the tail gas outlet pipe to prevent the clean water after spraying from being discharged with the tail gas outlet pipe). The concentrated phosphoric acid reacts with ammonia and flows back to the mixed acid storage tank. Part of the mixed acid storage tank is sprayed through the first external discharge pipe and the spray mechanism for recycling. The other part flows into the reaction vessel through the second external discharge pipe when the concentration in the mixed acid storage tank reaches pH 3.5 to continue reacting with the ammonia introduced through the ammonia inlet pipe to generate diammonium phosphate. The reaction reaches its endpoint at pH 8.

[0017] II. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system provided by this utility model has a first nozzle and a second nozzle in the spraying mechanism, one opening upward and the other opening downward, spraying alternately to make the spraying effect better.

[0018] III. The present invention provides a food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system, the setting of the baffle mechanism increases the spraying effect.

[0019] IV. The present invention provides a food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system, wherein a stirring device is installed on the mixed acid storage tank to prevent crystallization in the mixed acid storage tank.

[0020] V. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system provided by this utility model, with the setting of level gauge and feed valve, ensures that the liquid level in the mixed acid storage tank is maintained within a certain range.

[0021] VI. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system provided by this utility model has a first pH meter and a second pH meter for easy viewing of the pH value in the mixed acid storage tank and the reaction vessel. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of this utility model;

[0023] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of this utility model;

[0024] Figure 3 This is a schematic diagram of the spraying mechanism in this utility model;

[0025] Wherein: 100, exhaust gas treatment device; 110, spraying mechanism; 111, first spraying plate; 112, spraying inlet pipe; 113, second spraying plate; 114, first nozzle; 115, second nozzle; 120, baffle mechanism; 130, descaling mechanism; 131, third spraying plate; 132, third nozzle; 140, sleeve; 150, exhaust gas outlet pipe; 160, discharge port; 170, exhaust gas inlet pipe; 200, mixed acid storage tank; 210, first... External discharge pipe; 220, second external discharge pipe; 230, level gauge; 240, first pH meter; 300, reaction vessel; 310, ammonia inlet pipe; 320, gas outlet pipe; 330, second pH meter; 410, clean water inlet pipe; 420, clean water pump; 430, clean water storage tank; 510, food-grade concentrated phosphoric acid inlet pipe; 520, food-grade concentrated phosphoric acid pump; 530, food-grade concentrated phosphoric acid storage tank; 600, exhaust fan; 700, stirring device; 800, feed valve. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0027] Example 1

[0028] like Figure 1 As shown, a comprehensive utilization system for food-grade diammonium hydrogen phosphate tail gas includes a tail gas treatment device 100, a mixed acid storage tank 200, and a reaction vessel 300. The tail gas treatment device 100 has, from top to bottom, a spray mechanism 110, a baffle mechanism 120, and a descaling mechanism 130. The descaling mechanism 130 is connected to a clean water inlet pipe 410. A sleeve 140 is provided outside the descaling mechanism 130, and a tail gas outlet pipe 150 is provided inside the sleeve 140. The tail gas treatment device 100 has an air inlet and a discharge outlet 160 at its upper and lower ends, respectively. The lower part of the exhaust gas treatment device 100 is connected to the mixed acid storage tank 200, and the discharge port 160 is located inside the mixed acid storage tank 200. The mixed acid storage tank 200 is equipped with a food-grade concentrated phosphoric acid inlet pipe 510, a first exhaust pipe 210, and a second exhaust pipe 220. The first exhaust pipe 210 is connected to the feed end of the spray mechanism 110, and the second exhaust pipe 220 is connected to the reaction vessel 300. The reaction vessel 300 is also equipped with an ammonia inlet pipe 310 and an exhaust pipe 320. The exhaust pipe 320 is connected to the exhaust gas inlet pipe 170 and then to the air inlet. The first exhaust pipe 210 and the second exhaust pipe 220 are equipped with a transfer pump. This transfer pump is prior art and not the inventive point to be protected in this application; therefore, it will not be described in detail here.

[0029] Example 2

[0030] like Figure 2 and Figure 3As shown, a comprehensive utilization system for food-grade diammonium hydrogen phosphate tail gas includes a tail gas treatment device 100, a mixed acid storage tank 200, and a reaction vessel 300. The tail gas treatment device 100 has, from top to bottom, a spray mechanism 110, a baffle mechanism 120, and a descaling mechanism 130. The descaling mechanism 130 is connected to a clean water inlet pipe 410. A sleeve 140 is provided outside the descaling mechanism 130, and a tail gas outlet pipe 150 is provided inside the sleeve 140. The tail gas treatment device 100 has an air inlet and a discharge outlet 160 at its upper and lower ends, respectively. The lower part of the exhaust gas treatment device 100 is connected to the mixed acid storage tank 200, and the discharge port 160 is located inside the mixed acid storage tank 200. The mixed acid storage tank 200 is equipped with a food-grade concentrated phosphoric acid inlet pipe 510, a first exhaust pipe 210, and a second exhaust pipe 220. The first exhaust pipe 210 is connected to the feed end of the spray mechanism 110, and the second exhaust pipe 220 is connected to the reaction vessel 300. The reaction vessel 300 is also equipped with an ammonia inlet pipe 310 and an exhaust pipe 320. The exhaust pipe 320 is connected to the exhaust gas inlet pipe 170 and then to the air inlet. The first exhaust pipe 210 and the second exhaust pipe 220 are equipped with a transfer pump. This transfer pump is prior art and not the inventive point to be protected in this application; therefore, it will not be described in detail here.

[0031] The spraying mechanism 110 includes a first spray plate 111, a spray inlet pipe 112, and a second spray plate 113. The spray inlet pipe 112 is connected to the first spray plate 111 and the second spray plate 113. The first spray plate 111 is provided with a plurality of first nozzles 114, and the second spray plate 113 is provided with a plurality of second nozzles 115. The spray inlet pipe 112 is connected to a first outflow pipe 210. The first nozzles 114 open downwards, and the second nozzles 115 open upwards.

[0032] The partition mechanism 120 includes multiple downwardly arranged partitions, one end of which is connected to the inner wall of the exhaust gas treatment device 100, and a gap is provided between two adjacent partitions.

[0033] The descaling mechanism 130 includes a third spray plate 131 and a plurality of third nozzles 132 disposed at the lower end of the third spray plate 131. The upper end of the third spray plate 131 is connected to a clean water inlet pipe 410, and the third nozzles 132 open downwards.

[0034] An exhaust fan 600 is installed on the exhaust pipe 150.

[0035] The mixed acid storage tank 200 is equipped with a stirring device 700.

[0036] The food-grade concentrated phosphoric acid inlet pipe 510 is equipped with a food-grade concentrated phosphoric acid pump 520 and a food-grade concentrated phosphoric acid storage tank 530.

[0037] The clean water inlet pipe 410 is equipped with a clean water pump 420 and a clean water storage tank 430.

[0038] The water inlet pipe 410, the food-grade concentrated phosphoric acid inlet pipe 510, the first outlet pipe 210, the second outlet pipe 220, the gas outlet pipe 320, and the exhaust gas inlet pipe 170 are all equipped with feed valves 800.

[0039] The mixed acid storage tank 200 is equipped with a level gauge 230 and a first pH meter 240, and the reaction vessel 300 is equipped with a second pH meter 330.

[0040] Among them, the reaction vessel 300, exhaust fan 600, stirring device 700, food-grade concentrated phosphoric acid pump 520, food-grade concentrated phosphoric acid storage tank 530, clean water pump 420, clean water storage tank 430, feed valve 800, level gauge 230, first pH meter 240 and second pH meter 330 are all prior art and are not the inventive points to be protected in this application, and will not be described in detail here.

[0041] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0042] I. This utility model provides a comprehensive utilization system for food-grade diammonium hydrogen phosphate tail gas. The diammonium hydrogen phosphate tail gas enters the tail gas treatment device 100 through the tail gas inlet pipe 170. The ammonia gas in the diammonium hydrogen phosphate tail gas is sprayed by food-grade concentrated phosphoric acid in the spray mechanism 110. The concentrated phosphoric acid and ammonia gas undergo an acid-base neutralization reaction. The reaction is rapid, and the large amount of heat released can remove the moisture in the concentrated phosphoric acid. After passing through the baffle mechanism 120 and the sleeve 140, the tail gas flows through the descaling mechanism 130 to descale the tail gas (removing the ammonium hydrogen phosphate crystals around the pipe and its scale). To prevent dirt from clogging the pipes. A backflow valve is installed on the exhaust pipe 150 to prevent the clean water after spraying from being discharged through the exhaust pipe 150. Concentrated phosphoric acid reacts with ammonia and flows back to the mixed acid storage tank 200. Part of the mixed acid storage tank 200 is sprayed through the first external discharge pipe 210 and the spraying mechanism 110 for recycling. The other part, when the concentration in the mixed acid storage tank 200 reaches pH 3.5, flows through the second external discharge pipe 220 into the reaction vessel 300 to continue reacting with the ammonia gas introduced through the ammonia gas inlet pipe 310, generating diammonium phosphate. The reaction reaches its endpoint at pH 8.

[0043] II. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system provided by this utility model has a first nozzle 114 and a second nozzle 115 in the spraying mechanism 110, one opening upward and the other opening downward, spraying alternately to make the spraying effect better.

[0044] III. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system provided by this utility model has a baffle mechanism 120 that increases the spraying effect.

[0045] IV. The present invention provides a food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system, wherein a stirring device 700 is installed on the mixed acid storage tank 200 to prevent crystallization in the mixed acid storage tank 200.

[0046] V. The present invention provides a food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system. The liquid level gauge 230 and the feed valve 800 are set so that the liquid level in the mixed acid storage tank 200 is maintained within a certain range.

[0047] VI. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system provided by this utility model has a first pH meter 240 and a second pH meter 330 for easy viewing of the pH value in the mixed acid storage tank 200 and the reaction vessel 300.

[0048] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system, characterized in that: The system includes a tail gas treatment device (100), a mixed acid storage tank (200), and a reaction vessel (300). The tail gas treatment device (100) is equipped with, from top to bottom, a spray mechanism (110), a baffle mechanism (120), and a descaling mechanism (130). The descaling mechanism (130) is connected to a clean water inlet pipe (410). A sleeve (140) is provided outside the descaling mechanism (130), and a tail gas outlet pipe (150) is provided inside the sleeve (140). The tail gas treatment device (100) has an air inlet and a discharge outlet (160) at its upper and lower ends, respectively. The tail gas treatment device (100) contains... The lower part is connected to the mixed acid storage tank (200), and the discharge port (160) is located inside the mixed acid storage tank (200). The mixed acid storage tank (200) is equipped with a food-grade concentrated phosphoric acid inlet pipe (510), a first discharge pipe (210) and a second discharge pipe (220). The first discharge pipe (210) is connected to the feed end of the spraying mechanism (110), and the second discharge pipe (220) is connected to the reaction vessel (300). The reaction vessel (300) is also equipped with an ammonia inlet pipe (310) and an outlet pipe (320). The outlet pipe (320) is connected to the tail gas inlet pipe (170) and then to the inlet.

2. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system according to claim 1, characterized in that: The spraying mechanism (110) includes a first spraying plate (111), a spraying inlet pipe (112), and a second spraying plate (113). The spraying inlet pipe (112) is connected to the first spraying plate (111) and the second spraying plate (113). The first spraying plate (111) is provided with a plurality of first nozzles (114), and the second spraying plate (113) is provided with a plurality of second nozzles (115).

3. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system according to claim 1, characterized in that: The partition mechanism (120) includes multiple downwardly arranged partitions, one end of which is connected to the inner wall of the exhaust gas treatment device (100), and a gap is provided between two adjacent partitions.

4. The food-grade DPA off-gas comprehensive utilization system according to claim 1, characterized in that: The descaling mechanism (130) includes a third spray plate (131) and a plurality of third nozzles (132) disposed at the lower end of the third spray plate (131).

5. The food-grade DPA off-gas comprehensive utilization system according to claim 1, characterized in that: An exhaust fan (600) is installed on the exhaust pipe (150).

6. The food-grade DPA off-gas comprehensive utilization system according to claim 1, characterized in that: The mixed acid storage tank (200) is equipped with a stirring device (700).

7. The food-grade DPA off-gas comprehensive utilization system according to claim 1, characterized in that: The food-grade concentrated phosphoric acid inlet pipe (510) is equipped with a food-grade concentrated phosphoric acid pump (520) and a food-grade concentrated phosphoric acid storage tank (530).

8. The food-grade diammonium hydrogen phosphate tail gas comprehensive utilization system according to claim 1, characterized in that: The clean water inlet pipe (410) is equipped with a clean water pump (420) and a clean water storage tank (430).

9. The food-grade DPA off-gas comprehensive utilization system according to claim 1, characterized in that: Feed valves (800) are provided on the water inlet pipe (410), food-grade concentrated phosphoric acid inlet pipe (510), first outlet pipe (210), second outlet pipe (220), gas outlet pipe (320) and tail gas inlet pipe (170).

10. The food-grade DPA off-gas comprehensive utilization system according to claim 1, characterized in that: The mixed acid storage tank (200) is equipped with a level gauge (230) and a first pH meter (240), and the reaction vessel (300) is equipped with a second pH meter (330).

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