TW201912235A - Gas treatment method and apparatus for ammonia-contained gas - Google Patents

Abstract

A method and apparatus for treating an ammonia-contained waste gas, the method includes steps of: providing a mixed gas flow containing ammonia; introducing the mixed gas flow into an aqueous solution to form a pretreated gas flow and ammonia-rich aqueous solution; introducing the pretreated gas flow into a phosphoric acid solution that is reacted with the pretreated gas flow to form an ammonium-phosphate-rich mixture; respectively providing a recovery and a recycle treatment process for the ammonia-rich aqueous solution and the ammonium-phosphate-rich mixture; and then introducing the ammonium-phosphate-poor solution which is treated into the waste gas treatment units for recycling.

Description

 Ammonia-containing exhaust gas treatment method and device  

The present invention relates to an ammonia-containing waste gas treatment method and apparatus, and more particularly to a two-stage treatment method and apparatus for removing ammonia-containing waste gas.

With the influence of the greenhouse effect, countries around the world have paid attention to carbon dioxide emissions. In order to reduce the carbon dioxide content in the exhaust gas, the chemical absorption method captures carbon dioxide as the most commonly used carbon capture method. The process requires chemical absorption to capture carbon, and after regeneration, carbon dioxide is stored in various environments in various ways (for example, abandoned oil fields). The medium or underground salt water layer can reduce the amount of carbon dioxide in the exhaust gas discharged. The current chemical method captures carbon dioxide mainly by using carbon dioxide in a flue gas using alkaline, ammonia, an alcoholic amine aqueous solution, or an ionic solution. Although the carbon capture technology of alcohol amine chemical absorption liquid is used, the long history technology is mature, but it has high energy consumption for regeneration, high chemical price, easy deterioration of alcohol amine during use, high corrosivity and environmental concerns. Higher disadvantages, and because the alcohol amine chemical absorption liquid will react with the sulfide in the gas, it is necessary to carry out deep desulfurization procedures before carbon capture, and also increase the cost of carbon capture and limit the applicability. Relatively speaking, ammonia has the advantages of stable chemical properties, low price, low energy consumption for regeneration, and no known environmental concerns. Another gas containing SOx sulfide can also be desulfurized with ammonia water to form ammonium sulfate. Ammonium sulfate can be recycled as fertilizer. However, technically, it is necessary to face the problems caused by the high volatility of ammonia, and it is necessary to establish a cost-effective process technology.

However, the above-mentioned conventional ammonia water absorption method still has the following problems in practical use. The use of ammonia water to absorb carbon dioxide in the flue gas causes ammonia gas in the exhaust gas, and the human body has an odor threshold of about 5 ppm for ammonia gas. More than 5 ppm of the human body will feel the special odor of ammonia, and when the ammonia concentration is higher than about 20 ppm and it may cause irritation of the eyes, or even the respiratory tract. Therefore, when the concentration of ammonia in the flue gas emitted is too high, it will cause environmental problems. Among the current ammonia water capture technologies, ALSTOM's chilled-NH ₃ process is a process technology with large-scale industrial performance; its method is characterized by a low-temperature absorption process (absorption tower temperature of about 0 ° C to 10 ° C) To reduce ammonia emissions, but the investment cost of low-temperature process and subsequent operating costs are expensive, thus hindering industrial use. Therefore, many institutions in the world have developed normal-temperature ammonia water-carrying process technology; however, the results of the Australian test workshop show that high ammonia volatility will result in high ammonia concentration in the tail gas after carbon capture, and the tail gas must be further purified to meet environmental protection. The high cost, that is, the ammonia water capture method needs to establish a cost-effective exhaust gas purification technology.

Therefore, it is necessary to provide an ammonia-containing exhaust gas treatment method and device to solve the problems of the conventional technology.

The main object of the present invention is to provide a method and a device for purifying ammonia-containing exhaust gas, which utilizes two stages to remove ammonia gas contained in the exhaust gas, so as to reduce the ammonia gas content contained in the exhaust gas, thereby improving air quality and complying with environmental regulations.

A secondary object of the present invention is to provide an ammonia-containing waste gas treatment method and apparatus, which utilizes an aqueous solution to absorb a portion of the ammonia gas content in the exhaust gas, and then absorbs the ammonium phosphate solution to reduce the ammonia gas content contained in the exhaust gas. In turn, the ammonia-containing exhaust gas treatment efficiency is improved.

A secondary object of the present invention is to provide an ammonia-containing waste gas treatment method and apparatus, which utilizes an aqueous solution to first absorb most of the ammonia gas in the tail gas after carbon capture, and then absorb the residual ammonia gas in the exhaust gas by using an aqueous solution of ammonium phosphate. Remove and achieve an environmentally friendly and efficient method.

In order to achieve the above object, an embodiment of the present invention provides an ammonia-containing exhaust gas treatment method comprising the steps of: (a) providing a mixed gas containing ammonia; (b) mixing the mixed gas with Contact with the aqueous solution, the ammonia in the mixed gas is absorbed by the aqueous solution to form an aqueous ammonia solution and a pretreatment gas, and the ammonia aqueous solution is subjected to a recovery treatment procedure, and the aqueous solution after removing the ammonia is returned to reabsorb the ammonia in the exhaust gas. (c) contacting the pretreatment gas with a mixed solution of monophosphate, reacting the phosphoric acid mixture with the pretreatment gas to form an ammonium monophosphate rich solution; (d) performing a recovery treatment procedure on the ammonium phosphate rich solution, Removing a portion of the ammonia in the ammonium phosphate rich liquid to obtain an ammonium monophosphate recovery liquid; and (e) introducing the ammonium phosphate recovery liquid back into the pretreatment gas formed in the step (b), and absorbing the ammonium phosphate recovery liquid The ammonia in the pretreatment gas of step (c) is formed to form an ammonia water absorption liquid for recycling.

In one embodiment of the invention, the aqueous solution absorbs one of the mixed gases at an operating temperature of from 0 °C to 60 °C.

In an embodiment of the invention, the phosphoric acid mixture absorbs the mixed gas at an operating temperature of 10 ° C to 100 ° C.

In an embodiment of the present invention, the ammonium phosphate rich liquid comprises H ₃ PO ₄ , (NH ₄ )H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ and (NH ₄ ) ₃ PO ₄ , and the total of the above compounds The weight accounts for 5% to 40% of the total weight of the ammonium phosphate recovery liquid.

In an embodiment of the present invention, after the step (d), the NH ₃ /H ₃ PO ₄ molar ratio in the ammonium phosphate recovery liquid is less than 1.4, and after the step (c), the ammonium phosphate rich The NH ₃ /H ₃ PO ₄ molar ratio in the liquid is less than 1.8.

In an embodiment of the present invention, an ammonia-containing exhaust gas treatment device is provided, comprising: a first processing unit for accommodating an aqueous solution and a mixed gas, wherein the mixed gas contains at least ammonia, wherein the aqueous solution and the mixture The gas reacts to form an aqueous ammonia solution and a pretreatment gas, and the aqueous ammonia solution is led out through a first outlet tube; a regeneration unit is configured to collect the extracted aqueous ammonia solution and treat the aqueous ammonia solution to produce a regeneration An aqueous solution and an ammonia gas, which is returned to the first processing unit via a first introduction tube; a second processing unit for containing the phosphoric acid mixture and the pretreatment gas, the pretreatment gas containing at least Ammonia, wherein the phosphoric acid mixture reacts with the pretreatment gas to form an ammonium monophosphate rich liquid, the ammonium phosphate rich liquid is discharged through a second outlet tube; and a recovery processing unit for collecting the extracted ammonium phosphate rich liquid And treating the ammonium phosphate rich liquid to produce an ammonium monophosphate recovery liquid and an ammonia gas, and the ammonium phosphate recovery liquid is guided back to the second inlet pipe Second processing unit.

In an embodiment of the invention, the regeneration unit and the recovery processing unit are respectively a distiller, and the first processing unit and the second processing unit are respectively a rinsing tower.

In one embodiment of the invention, the mixed gas is an ammonia containing gas treated via a carbon dioxide absorber.

In an embodiment of the invention, one of the first processing units has an operating temperature of 0 ° C to 60 ° C, and one of the second processing units has an operating temperature of 10 ° C to 100 ° C.

1‧‧‧ mixed gas

2‧‧‧Pretreatment gas

3‧‧‧Exhaust

11‧‧‧First Stage Purification Procedure

111‧‧‧ aqueous solution

112‧‧‧Ammonia-containing aqueous solution

12‧‧‧Second stage purification process

121‧‧‧phosphoric acid mixture

122‧‧‧Ammonium phosphate rich liquid

13‧‧‧Regeneration process

131‧‧‧Renewed aqueous solution

14‧‧‧Recycling procedures

141‧‧‧Ammonium phosphate recovery solution

41‧‧‧First Processing Unit

411‧‧‧ aqueous solution

412‧‧‧Ammonia-containing aqueous solution

413‧‧‧First outlet tube

414‧‧‧First duct

415‧‧‧First pump

42‧‧‧Second processing unit

421‧‧‧phosphoric acid mixture

422‧‧‧Ammonium phosphate rich liquid

423‧‧‧Second outlet tube

43‧‧‧Renewal unit

431‧‧‧Renewed aqueous solution

432‧‧‧First introduction tube

44‧‧‧Recycling unit

441‧‧‧Ammonium phosphate recovery solution

442‧‧‧Second introduction tube

45‧‧‧CO2 absorption tower

451‧‧‧Second duct

452‧‧‧Second pump

46‧‧‧ pure water storage tank

461‧‧‧ pure water pipe

47‧‧‧phosphoric acid storage tank

471‧‧‧phosphorus tube

Fig. 1 is a block diagram showing the flow of an ammonia-containing waste gas treatment method according to an embodiment of the present invention.

Fig. 2 is a graph showing the thermodynamic equilibrium characteristics of ammonia gas at different temperatures according to an embodiment of the present invention.

Figure 3 is a diagram showing the gas-liquid thermodynamic equilibrium of the NH ₃ -H ₃ PO ₄ -H ₂ O system of one embodiment of the present invention.

Fig. 4 is a schematic view showing an ammonia-containing exhaust gas treating apparatus according to an embodiment of the present invention.

The above and other objects, features and advantages of the present invention will become more <RTIgt; Furthermore, the directional terms mentioned in the present invention, such as upper, lower, top, bottom, front, rear, left, right, inner, outer, side, surrounding, central, horizontal, horizontal, vertical, longitudinal, axial, Radial, uppermost or lowermost, etc., only refer to the direction of the additional schema. Therefore, the directional terminology used is for the purpose of illustration and understanding of the invention.

Referring to FIG. 1 , an ammonia-containing exhaust gas treatment method according to an embodiment of the present invention mainly comprises the following steps: providing a mixed gas 1 containing ammonia; and introducing the mixed gas 1 into a first stage purification process In contact with an aqueous solution 111, the ammonia in the mixed gas 1 is absorbed by the aqueous solution 111 to form an aqueous ammonia containing solution 112 (also referred to as an aqueous ammonia rich solution) and a pretreatment gas (also referred to as pre-cleaning treatment). The gas 2 may be optionally introduced into a regeneration treatment program 13 to remove ammonia in the ammonia-containing aqueous solution 112 to obtain a regenerated aqueous solution 131. Alternatively, the regenerated aqueous solution 131 can be returned to the first stage purification program 11. The pretreatment gas 2 is contacted with the monophosphoric acid mixed solution 121 in a second stage purification process 12, and the phosphoric acid mixed solution 121 is reacted with the pretreatment gas to form an ammonium monophosphate rich liquid 122; the ammonium phosphate rich liquid is recovered. Processing the program 14 to remove a portion of the ammonia in the ammonium phosphate rich liquid 122 to obtain an ammonium monophosphate recovery liquid 141; and returning the ammonium phosphate recovery liquid 141 back to the untreated pretreatment gas 2 to make the ammonium phosphate The recovered liquid 141 absorbs the ammonia in the pretreatment gas 2 to form an aqueous ammonia absorbent for recycling. DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to Figures 1 through 2, respectively, detailing the implementation details of the various steps of an embodiment and the principles thereof.

Referring to FIG. 1, an ammonia-containing exhaust gas treatment method according to an embodiment of the present invention first provides a continuous mixed gas 1 containing ammonia. In this step, the mixed gas 1 may be an ammonia-containing gas treated through a carbon dioxide absorption tower. Preferably, the mixed gas 1 is exhaust gas after the carbon dioxide-containing gas generated by the iron-making hot air furnace exhaust gas or other process unit absorbs carbon dioxide through the ammonia water absorption liquid. The ammonia-containing gas usually contains 10,000 ppm to 50,000 ppm (5%) of ammonia gas.

Next, the ammonia-containing exhaust gas treatment method according to an embodiment of the present invention contacts the mixed gas 1 with an aqueous solution 111 to perform the first-stage purification process 11 to remove a part of the ammonia gas in the mixed gas 1. The ammonia in the mixed gas 1 is absorbed by the aqueous solution 111, so that the aqueous solution 111 absorbs ammonia gas to form an aqueous ammonia-containing solution 112, and the mixed gas 1 removes a part of the ammonia gas to form a pretreatment gas 2. Preferably, the ammonia gas portion removed by the mixed gas 1 accounts for 80 to 98% of the total ammonia content in the mixed gas 1 in terms of volume (or weight). The aqueous solution may be pure water or regenerated water containing ammonia after being regenerated. After the aqueous solution treatment, a part of the ammonia gas in the mixed gas 1 is dissolved in water to become an ammonium ion. In the present embodiment, the pretreatment gas 2 after the first stage purification process has been used, and the ammonia content in the pretreatment gas 2 can be initially reduced to 1000 to 5000 ppm; since the ammonia content is not required to be low, Therefore, the cleanliness required for the aqueous solution used is low (for example, the content of ammonium in the aqueous solution) and the operating temperature can be high, so that the operating cost can be reduced. It will be appreciated that for better processing efficiency, the first stage purification process can be operated at a low temperature operating condition to mitigate the problem of ammonia slip.

The ammonia-containing exhaust gas treatment method according to an embodiment of the present invention, after the first-stage purification process 11, is followed by a second-stage purification process 12 in which the pretreatment gas 2 is contacted with the monophosphoric acid mixed solution 121 to form the phosphoric acid mixed solution. 121 reacts with the pretreatment gas 2 to form an ammonium monophosphate rich liquid 122 (i.e., NH ₃ /H ₃ PO ₄ molar ratio is greater than 1.4). Thus, most of the ammonia gas in the treated pretreatment gas 2 reacts with the phosphoric acid mixed solution to form ammonium phosphate, and finally, the exhaust gas 3 after the treatment is discharged. In the present embodiment, after the first stage purification process 11 and the second stage purification process 12, the ammonia concentration in the exhaust gas can be reduced to less than 50 ppm. The phosphoric acid mixture 121 may be a solution of phosphoric acid and water, or a mixture of phosphoric acid, ammonium phosphate and water, for example, an aqueous phosphoric acid solution containing 5 to 40% by weight of phosphoric acid. Since phosphoric acid is a tri-protonic acid, a large number of hydrogen groups can be substituted by an ammonium group, so that a large amount of ammonia gas can be absorbed, and the produced ammonium phosphate rich liquid 122 has H ₃ PO ₄ and (NH ₄ )H ₂ PO. ₄ , (NH ₄ ) ₂ HPO ₄ and (NH ₄ ) ₃ PO ₄ and other ingredients can be used as fertilizer, can also be recycled and recycled. The ammonium phosphate rich liquid 122 contains, for example, 5 to 40% by weight of H ₃ PO ₄ in weight percent. Generally, the ratio of the original number of moles of NH ₃ and H ₃ PO ₄ in the solution is used as the absorption saturation index, and the ratio of the molar ratio of NH ₃ /H ₃ PO ₄ in the phosphoric acid mixture 141 is 1 to 1.4, and the NH in the ammonium phosphate rich solution 122 is NH. _{The 3} /H ₃ PO ₄ molar ratio is less than 1.8.

In the present embodiment, the absorbed ammonium phosphate rich liquid 122 is led to a further recovery treatment program 14 to further remove a portion of the ammonia in the ammonium phosphate rich liquid 122 to obtain an ammonium monophosphate recovery liquid 141. In the present embodiment, the phosphoric acid mixed solution 121 and the ammonium phosphate recovery liquid 141 are the same solution, and the contents of the ammonium are different only. In other embodiments, the phosphoric acid mixed solution 121 is a solution in which the ammonium phosphate recovery liquid 141 is further added with phosphoric acid to adjust the phosphoric acid content. In the present embodiment, the recovery processing program 14 may be to reduce ammonium in the ammonium phosphate rich liquid 122 to gaseous ammonia by using one water vapor, and remove a part of ammonia in the ammonium phosphate rich liquid 122, wherein the phosphoric acid mixed liquid the NH ₃ / H ₃ PO ₄ molar ratio of the number 141 is 1 to 1.4, the rich ammonium phosphate solution NH ₃ / H ₃ PO ₄ ratio of 122 moles of less than 1.8. In the present embodiment, the water vapor can be generated by heating the waste heat generated by the steelmaking hot blast stove or the coke oven, thereby reducing the operation cost. Other ways of removing ammonium from the ammonium phosphate rich liquid 122 are also contemplated.

In the present embodiment, the ammonium phosphate recovery liquid 141 after the recovery treatment can be finally returned to another untreated pretreatment gas 2, so that the ammonium phosphate recovery liquid absorbs the ammonia in the other pretreatment gas, thereby Forming an ammonia water absorbing liquid for recycling, for example, for treating exhaust gas generated by a steelmaking hot blast stove or a coke oven to absorb carbon dioxide, and the exhaust gas remaining after the exhaust gas is absorbed by carbon dioxide is provided at the beginning of the embodiment. Mixing gas 1.

As described above, in one embodiment, after the first stage purification process, the ammonia in the mixed gas 1 is absorbed by the aqueous solution 111 to form an aqueous ammonia containing solution 112, and the aqueous ammonia containing solution can be optionally introduced into a regeneration treatment program 13 In order to remove ammonia in the aqueous ammonia-containing solution 112, a regenerated aqueous solution 131 is obtained. In the present embodiment, the regeneration treatment program 13 may reduce the ammonium in the ammonia-containing aqueous solution 112 to gaseous ammonia by using one water vapor, and remove a part of the ammonia in the ammonia-containing aqueous solution 112. In the present embodiment, the water vapor can be generated by heating the waste heat generated in the production process (for example, waste heat generated by a steelmaking hot blast stove or a coke oven), so that the operation cost can be reduced. Other ways in which ammonia can be removed from the aqueous ammonia containing solution 112 are also contemplated.

Referring to Figure 2, it shows the thermodynamic equilibrium characteristics of ammonia at different temperatures. When the contact temperature of the aqueous solution with the ammonia gas is too high, the ammonia gas easily escapes from the aqueous solution, resulting in poor absorption efficiency. Therefore, in order to meet environmental protection requirements, in an embodiment, in the first stage purification process 11, the mixed gas 1 is contacted with the aqueous solution 111, and the operating temperature of one of the aqueous solutions 111 may be 0 ° C to 60 ° C, via lowering the aqueous solution. The cleanliness of 131 (that is, allowing higher ammonia concentration) and increasing the temperature of the purification program 11 can greatly reduce the operating cost, although the concentration of ammonia in the pretreatment gas 2 is increased; the ammonia in the pretreatment gas 2 can be further purified. 12 Remove to environmental requirements. It will be appreciated that when the first stage purification process 11 requires better ammonia removal efficiency, an additional source of energy may be applied to operate the aqueous solution 111 below room temperature.

Referring to Figure 3, it is shown that the gas-liquid thermodynamic equilibrium diagram of the NH ₃ -H ₃ PO ₄ -H ₂ O system is calculated according to thermodynamics. In this embodiment, 7 mole/L phosphoric acid is used. It can be understood from the drawing that the use of phosphoric acid to absorb ammonia gas can also have a desired purification effect at a high temperature without additional energy application to lower the operating temperature. Further, the first stage purification process 11 is performed first, and the aqueous solution 111 is used to absorb a portion of the ammonia gas. In the second stage purification process 12, a smaller amount of the aqueous ammonium phosphate solution can be used, thereby reducing the operation cost and the operational risk. The ammonium phosphate rich liquid 122 comprises H ₃ PO ₄ , (NH ₄ )H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ and (NH ₄ ) ₃ PO ₄ , and the preferred operating conditions are that the total weight of the above compound accounts for The ammonium phosphate recovery liquid 141 has a total weight of 5% to 40%. In order to have sufficient hydrogen group exchange with ammonium and have better operating efficiency, the NH ₃ /H ₃ PO ₄ molar ratio in the ammonium phosphate recovery liquid 141 is controlled to be less than 1.4 (also referred to as ammonium phosphate deficiency). liquid). And in order to maintain a better purification ability, the NH ₃ /H ₃ PO ₄ molar ratio in the ammonium phosphate rich liquid 122 is controlled to be less than 1.8.

Referring to FIG. 4, an ammonia-containing exhaust gas treatment device of the present invention comprises a first processing unit 41 for accommodating an aqueous solution and a mixed gas 1 containing at least ammonia, wherein the aqueous solution 411 After the immersion is contacted with the mixed gas 1, the aqueous solution 411 and the mixed gas 1 are reacted to absorb the ammonia gas in the mixed gas 1 to form an aqueous ammonia solution 412 and a pretreatment gas 2, and the aqueous ammonia solution is passed through a first An outlet tube 413 is derivable, and an ammonia-containing aqueous solution storage tank (not shown) may be selectively disposed in the apparatus to store the ammoniated aqueous solution 412 or directly sent to a regeneration unit 43 for collecting and exporting The aqueous ammonia solution 412 is treated to remove a portion of the ammonium ions to produce a regenerated aqueous solution 431 and an ammonia gas. The treated regenerated aqueous solution 431 is returned to the first via a first introduction tube 432. A processing unit 41. As such, the regeneration aqueous solution 431 can be recycled to the first treatment unit 41 to initially remove ammonia gas in the mixed gas 1. In this embodiment, a pure water storage tank 46 can be disposed to store pure water. When the purity of the regenerated aqueous solution 431 does not meet the demand, the pure water storage tank 46 delivers pure water through a pure water delivery pipe 461 to the regeneration. The aqueous solution 431 is used to increase the purity of the regenerated aqueous solution 431. To reduce operating costs, the first processing unit 41 is operable at room temperature (e.g., 20 ° C to 50 ° C).

The pretreatment gas 2 formed after the preliminary treatment of the mixed gas 1 is sent to a second processing unit 42 through a first conveying pipe, and a first pump is selectively disposed on the first conveying pipe to adjust the The pretreatment gas 2 enters the flow rate of the second treatment unit 42 for containing the phosphoric acid mixed solution 421 and the pretreatment gas 2, and the pretreatment gas 2 contains at least ammonia. In the present embodiment, the phosphoric acid mixture 421 rinses the pretreatment gas 2 to react the phosphoric acid mixture 421 and the pretreatment gas 2 to form a purification mixed gas and an ammonium monophosphate rich liquid 422, wherein the ammonium phosphate rich The liquid 422 absorbs the ammonia gas contained in the pretreatment gas 2, and the reacted ammonium phosphate rich liquid 422 is led out through a second outlet pipe 423, and the ammonium phosphate rich liquid storage tank can be selectively disposed in the apparatus (not The graph) is used to store the ammonium phosphate rich liquid 422 or directly to a recovery processing unit 44. The recovery processing unit 44 is configured to collect the extracted ammonium phosphate rich liquid 422 and process the ammonium phosphate rich liquid 422 to remove part of the ammonium ions to generate an ammonium monophosphate recovery liquid 441 and an ammonia gas, and the treated The ammonium phosphate recovery liquid 441 is led back to the second processing unit 42 via a second introduction tube 442. In this way, the ammonium phosphate recovery liquid 441 can be recycled to the second treatment unit 42 to remove the ammonia gas in the pretreatment gas 2 below a target value to become the purification mixed gas to meet environmental protection requirements.

In one embodiment, the regeneration unit 43 and the recovery processing unit 44 are each a distiller, and the regeneration unit 43 and the recovery processing unit 44 are the aqueous ammonia solution 412 and the ammonium phosphate rich solution 422 via water vapor. The ammonium removal in the formation forms the regenerated aqueous solution 431 and the ammonium phosphate recovery liquid 441. The water vapor can be generated by heating the waste heat generated in the production process (for example, waste heat generated by a steelmaking hot blast stove or a coke oven), which can reduce operating costs. The first processing unit 41 and the second processing unit 42 can each be a rinsing tower, such as a packed scrubber or a venturi scrubber. In this embodiment, preferred operating conditions are H ₃ PO ₄ , (NH ₄ )H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ and (NH ₄ ) ₃ PO ₄ are the total weight of the above compound in the ammonium phosphate. The total weight of the recovered liquid 441 is 5% to 40%. In the present embodiment, it may be provided with a storage tank 47 storing phosphoric acid, H ₃ PO ₄ accounted for when the overall weight of 441 was recovered ammonium phosphate of less than 5%, the phosphoric acid storage tank 47 via a delivery tube 471 conveyed to the phosphoric acid This ammonium phosphate recovery liquid 441. In order to have sufficient hydrogen radical exchange with ammonium and to have better operational efficiency, the NH ₃ /H ₃ PO ₄ molar ratio in the ammonium phosphate recovery liquid 441 is controlled to be less than 1.4. And in order to maintain a better purification ability, the NH ₃ /H ₃ PO ₄ molar ratio in the ammonium phosphate rich liquid 422 is controlled to be less than 1.8.

In one embodiment, the mixed gas 1 is an ammonia-containing gas that has been subjected to carbon capture by an ammonia absorption method via a carbon dioxide absorption tower 45, and is sent to the first processing unit 41 via a second transfer pipe 451. The second delivery tube can be equipped with a second pump 452 to deliver the mixed gas 1 into the first processing unit 41.

In one embodiment, one of the first processing units has an operating temperature of 0 ° C to 60 ° C and one of the second processing units has an operating temperature of 10 ° C to 100 ° C.

As described above, the ammonia-containing exhaust gas treatment method and apparatus of the present invention utilizes the two-stage removal of the ammonia gas contained in the exhaust gas, which can actually reduce the ammonia gas content contained in the exhaust gas, thereby improving the air quality and conforming to the conventional technology. Environmental protection regulations; and the ammonia-containing waste gas treatment method and device of the present invention utilizes an aqueous solution to absorb a part of the ammonia gas content in the exhaust gas first, and then absorbs the ammonium phosphate solution, in addition to reducing the ammonia gas content contained in the exhaust gas, Further improve the treatment efficiency of ammonia-containing exhaust gas and significantly reduce operating costs.

The present invention has been disclosed in its preferred embodiments, and is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

Claims (10)

 An ammonia-containing waste gas treatment method comprising the steps of: (a) providing a mixed gas containing ammonia; (b) contacting the mixed gas with an aqueous solution, so that ammonia in the mixed gas is absorbed by the aqueous solution; Forming an aqueous ammonia solution and a pretreatment gas; (c) contacting the pretreatment gas with the monophosphoric acid mixture, and reacting the phosphoric acid mixture with the pretreatment gas to form an ammonium monophosphate rich solution; (d) The ammonium phosphate rich liquid is subjected to a recovery treatment procedure to remove a part of the ammonia in the ammonium phosphate rich liquid to obtain an ammonium monophosphate recovery liquid; and (e) the ammonium phosphate recovery liquid is returned to the step (c) to make the ammonium phosphate The recovered liquid absorbs the ammonia in the pretreatment gas of the step (b).    The method for treating ammonia-containing waste gas according to claim 1, wherein after the step (b), the method further comprises: (b1) introducing the aqueous ammonia solution into a regeneration treatment program to remove ammonia in the aqueous ammonia solution; A regenerated aqueous solution is obtained.    The method for treating ammonia-containing waste gas according to claim 1, wherein in the step (b), the operating temperature of one of the aqueous solutions is from 0 ° C to 60 ° C.    The method for treating ammonia-containing waste gas according to claim 3, wherein the phosphoric acid mixture has an operating temperature of 10 ° C to 100 ° C.   The method for treating ammonia-containing waste gas according to claim 1, wherein in the step (c), the ammonium phosphate rich liquid comprises H ₃ PO ₄ , (NH ₄ )H ₂ PO ₄ , (NH ₄ ) ₂ HPO. ₄ and (NH ₄ ) ₃ PO ₄ , and the total weight of the above compound accounts for 5% to 40% of the total weight of the ammonium phosphate recovery liquid. The method for treating ammonia-containing waste gas according to claim 1, wherein after the step (d), the NH ₃ /H ₃ PO ₄ molar ratio in the ammonium phosphate recovery liquid is less than 1.4, and the step is performed ( After c), the NH ₃ /H ₃ PO ₄ molar ratio in the ammonium phosphate rich solution is less than 1.8.  An ammonia-containing exhaust gas treatment device comprising: a first processing unit for accommodating an aqueous solution and a mixed gas, wherein the mixed gas contains at least ammonia, wherein the aqueous solution and the mixed gas react to form an aqueous ammonia solution and a pre-form Processing a gas, the aqueous ammonia solution is led out through a first outlet tube; a regeneration unit for collecting the derived aqueous ammonia solution and treating the aqueous ammonia solution to produce a regeneration aqueous solution and an ammonia gas, the regeneration aqueous solution via a first introduction tube is led back to the first processing unit; a second processing unit is configured to accommodate the phosphoric acid mixed solution and the pretreatment gas, the pretreatment gas containing at least ammonia, wherein the phosphoric acid mixture and the pretreatment The treatment gas reacts to form an ammonium monophosphate rich liquid, and the ammonium phosphate rich liquid is led out through a second outlet tube; and a recovery processing unit for collecting the extracted ammonium phosphate rich liquid and treating the ammonium phosphate rich liquid to produce An ammonium monophosphate recovery solution and an ammonia gas, which is returned to the second processing unit via a second introduction tube.    The ammonia-containing waste gas treatment device according to claim 7, wherein the regeneration unit and the recovery treatment unit are each a distiller, and the first treatment unit and the second treatment unit are respectively a rinsing tower.    The ammonia-containing exhaust gas treatment device according to claim 7, wherein the mixed gas is an ammonia-containing gas treated through a carbon dioxide absorption tower.    The ammonia-containing exhaust gas treating apparatus according to claim 7, wherein an operating temperature of one of the first processing units is from 0 ° C to 60 ° C, and an operating temperature of one of the second processing units is from 10 ° C to 100 ° C.