Process for recovery of ammonia

Abstract

The present invention provides a method for recovering ammonia, the method comprising: a step S1 for providing a mixed gas comprising ammonia; a step S2 for dissolving ammonia in water; a step S3 for degassing the ammonia water in which ammonia is dissolved, thereby separating the water from the ammonia gas; and a step (S4) for purifying the removed ammonia.

Description

Technical Field

[0001] The present disclosure relates to a method for recovering ammonia from a mixed gas. More specifically, the present disclosure relates to a method for recovering ammonia, which comprises recovering ammonia from a mixed gas containing various substances (NH 3 , H 2 S, CO 2 , H 2 O, etc.) and recover high-purity ammonia of 90% or more, and also prevent the formation of solid salts during the recovery process, thereby having a high ammonia recovery efficiency. Background Art

[0002] Ammonia has the chemical formula NH 3 A compound of nitrogen and hydrogen. Since ammonia boils at -33.34°C (-28.012°F) at 1 atmosphere of pressure, liquid ammonia may need to be stored at high pressure or cryogenic temperatures.

[0003] One of the commercial uses of ammonia may be as a process gas in the manufacture of semiconductor materials. For example, ammonia may be used for epitaxial deposition of semiconductor materials in a process known as metal-organic chemical vapor deposition (MOCVD).

[0004] Of the many gases used in making LEDs using MOCVD, ammonia is probably the most expensive substance, probably due in part to the high purity required of the ammonia process gas. Since ammonia requires high flow rates during the nitride crystal growth process, even trace amounts of impurities in the gas can result in a significant number of undesired atoms being included in the device. For example, when water (H2O) is present in the ammonia gas, the amount of impurities in the gas can be increased. 2 O) or oxygen (O 2 ) molecules, oxygen atoms may be included in the crystal structure of LED devices even at trace concentrations exceeding a few parts per billion (ppb). Therefore, modern LEDs can usually be made using ammonia containing 1 ppb or less of water or oxygen.

[0005] Ammonia can also be used in chemical reactions, one of which is as a NOx reducing agent in selective catalytic reduction (SCR). SCR technology can be used as a technology for removing NOx generated by combustion facilities such as power plants (which are stationary sources) or mobile sources such as cars. In this case, urea water can be used as a reducing agent, and since urea water can be decomposed at high temperatures and can become ammonia, which can then react with NOx, this can be the same technology.

[0006] Recently, as environmental issues increase, SCR facilities for removing NOx increase, and thus, the amount of ammonia used also increases, so that a technology for supplying a large amount of high-purity ammonia may be necessary.

[0007] Technologies for synthesizing and separating ammonia can generally include synthesizing H from natural gas 2 , react with nitrogen separated by air separation unit (ASU) to synthesize NH 3 In most cases, the difference in boiling points between ammonia, hydrogen and nitrogen can be used for separation.

[0008] However, the present disclosure may focus primarily on recovering NH generated in high concentrations in the middle of industrial processes. 3 Since it is difficult to directly recover ammonia in the prior art, ammonia may be burned at high temperature and may be used as heat energy. However, the present disclosure may provide a method and apparatus for selectively separating ammonia from an intermediate substance of a process containing various substances.

[0009] In addition to ammonia, H 2 S, CO 2 , H 2 O etc. as intermediate substances, and in particular, H 2 S and CO 2 It is highly reactive with ammonia, making H 2 S and CO 2 When cooling at room temperature, salts can form, which can lead to a reduction in the diameter of the pipeline. For this reason, in order to selectively separate ammonia, it may be necessary to control the boiling point difference and also the generation of solid salts.

[0010] In addition, due to the NH 3 , H 2 S, CO 2 As a substance with high solubility in water, techniques for selective separation may be necessary. 3 It can be dissolved in water up to about 30%, but H 2 The solubility of S may be relatively low, at 3 g / L, and CO 2 The solubility of NH4+ can be 1.3 g / L, and this solubility difference can be used to recover high-purity NH4+. 3 .

[0011] [Prior art]

[0012] [Patent References]

[0013] (Cited Document 1) Korean Patent Publication No. 1925612 Summary of the invention

[0014] Technical issues

[0015] One aspect of the present disclosure is to provide a method for removing impurities other than ammonia from a mixed gas and recovering high-purity ammonia.

[0016] Technical Solution

[0017] One aspect of the present disclosure provides an ammonia recovery unit comprising:

[0018] A mixed gas cooler 1, an ammonia absorption tower 2, an absorption liquid supply pump 3, an absorption liquid cooler 4, an absorption liquid degassing tower 5, a cooler 6 of the degassing tower, a reboiler 7 of the degassing tower, a cooler 8 on the upper end and the rear end of the degassing tower, a cooler 9 on the lower end and the rear end of the degassing tower, a first ammonia purification tower 10, a cooler 11 of the first ammonia purification tower, a reboiler 12 of the first ammonia purification tower, a second ammonia purification tower 13, a cooler 14 of the second ammonia purification tower, and a reboiler 15 of the second ammonia purification tower.

[0019] Another aspect of the present disclosure provides a method for recovering ammonia, which includes: an operation S1 of providing a mixed gas containing ammonia; an operation S2 of dissolving ammonia in water; an operation S3 of degassing the ammonia water containing dissolved ammonia to separate water and ammonia gas from each other; and an operation S4 of purifying the degassed ammonia.

[0020] Beneficial Effects

[0021] According to one aspect of the present disclosure, a method for efficiently recovering high-concentration ammonia by efficiently removing hydrogen sulfide and carbon dioxide from a mixed gas may be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A diagram showing the components of an ammonia recovery device according to the present disclosure and the connection relationship therebetween;

[0023] Figure 2 1 is a diagram illustrating a method for recovering ammonia, showing the flow of fluid streams ([A] to [S]) occurring during the implementation of the method for recovering ammonia according to the present disclosure. DETAILED DESCRIPTION

[0024] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the embodiments of the present disclosure may be modified in various other forms, and the scope of the present disclosure is not limited to the embodiments described below. In addition, embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the relevant art.

[0025] According to one aspect of the present disclosure, an ammonia recovery device including the following facilities may be provided:

[0026] A mixed gas cooler 1, an ammonia absorption tower 2, an absorption liquid supply pump 3, an absorption liquid cooler 4, an absorption liquid degassing tower 5, a cooler 6 of the degassing tower, a reboiler 7 of the degassing tower, a cooler 8 on the upper end and the rear end of the degassing tower, a cooler 9 on the lower end and the rear end of the degassing tower, a first ammonia purification tower 10, a cooler 11 of the first ammonia purification tower, a reboiler 12 of the first ammonia purification tower, a second ammonia purification tower 13, a cooler 14 of the second ammonia purification tower, and a reboiler 15 of the second ammonia purification tower.

[0027] According to another aspect of the present disclosure, a method for recovering ammonia includes: step S1 of providing a mixed gas containing ammonia; step S2 of dissolving ammonia in water; step S3 of degassing the ammonia water in which ammonia is dissolved to separate water and ammonia gas from each other; and step S4 of purifying the degassed ammonia.

[0028] In the following, please refer to Figure 1 and Figure 2 Each step of the method of the present disclosure is described in more detail.

[0029] In step S1, a mixed gas containing ammonia may be provided. The mixed gas may be cooled by a mixed gas cooler 1 to allow the ammonia to be more easily dissolved in water in the following step S2.

[0030] For example, the mixed gas may be cooled to 5°C to 80°C, more preferably 10°C to 40°C.

[0031] 80° C. or higher may mean that the process temperature is used as it is without heat exchange, and when cooled to a temperature lower than 5° C., solid salt may be generated, which may cause difficulty in operation.

[0032] Step S2 may be a step of cooling and absorbing ammonia with water in the ammonia absorption tower 2 and producing ammonia water, and may include supplying water to the mixed gas and recovering the ammonia contained in the mixed gas. This ammonia recovery may be a method commonly used in the prior art, and ammonia water may be produced by absorbing ammonia by spraying a large amount of water to the mixed gas. For example, by spraying water to the mixed gas, the mixed gas may be separated into water that absorbs ammonia and residual gas that is insoluble in water. In this case, it may be preferred to spray water countercurrently to the flow of the mixed gas.

[0033] High-concentration ammonia can be recovered from the aqueous ammonia produced by step S2, and if desired, a portion of the aqueous ammonia produced can be separated and used as an absorbent to remove acid gas from COG.

[0034] Since the dissolution reaction of ammonia in water may be an exothermic reaction (when dissolved in water at 25° C., enthalpy change ΔH°=−30.50 kJ / mol), cooling water may be supplied through the absorption liquid cooler 4 in step S2 .

[0035] More specifically, the temperature of the sprayed water may be 5°C to 45°C, and more preferably 10°C to 40°C.

[0036] When the water temperature is lower than 5°C, cooling water may need to be generated by a facility such as a refrigerator, which may increase the required electricity cost. On the other hand, when the water temperature exceeds 45°C, the gas solubility may decrease as the temperature increases, so that the amount of ammonia absorbed into the water may decrease.

[0037] In step S2, in addition to ammonia, hydrogen sulfide (H 2 S) and carbon dioxide (CO 2 ) can be dissolved, and hydrogen sulfide can have a solubility of 3 g / L and carbon dioxide has a solubility of 1.3 g / L (which is a trace amount) compared to ammonia which can be dissolved at 30% at room temperature, and therefore, the material can be purified in a subsequent distillation tower to remove impurity gases, and high-purity ammonia can be recovered.

[0038] The ammonia water produced in step S2 can be recycled to the lower end of the ammonia absorption tower 2, and the impurity gases such as hydrogen sulfide (H2S) dissolved in the water that has not been sprayed can be recycled to the lower end of the ammonia absorption tower 2. 2 S) and carbon dioxide (CO 2 ) can be separated from the ammonia gas and can be discharged or captured through the upper end of the ammonia absorption tower 2.

[0039] In step S2, hydrogen sulfide (H 2 S) and carbon dioxide (CO 2 ) can be separated from the ammonia gas at 99% or more of the initial impurity gas flow rate in step S1, and can be discharged or captured at the upper end of the ammonia absorption tower 2.

[0040] Step S3 may be a step of stripping ammonia gas from the aqueous ammonia produced in step S2 through the absorption liquid degassing tower 5, and may be performed using the difference in boiling points between ammonia and water.

[0041] In step S3, the ammonia water may be vaporized by heating through the reboiler 7 of the degassing tower, and the vaporized ammonia water may be recooled by the cooler 6 of the degassing tower. In this case, due to the difference in boiling points between ammonia and water, degassing may occur while water is liquefied and recovered to the lower part.

[0042] In order to perform step S3, the internal temperature of the absorption liquid degassing tower 5 may be 100°C to 200°C, more specifically, 110°C to 170°C.

[0043] When the internal temperature of the absorption liquid degassing tower is lower than 100° C., there may be a problem that dissolved ammonia may not be sufficiently recovered, and in this case, when ammonia remains in the recycled fluid, the absorption capacity may be reduced, which may affect the absorption tower. On the other hand, when the internal temperature of the absorption liquid degassing tower 5 exceeds 200° C., both ammonia and water may be vaporized, which may cause a problem that the degassing tower may not be able to perform the function of recovering and separating ammonia from the solution.

[0044] In addition, in this case, the pressure in the absorption liquid degassing tower 5 may be 1 kg / cm 2 Up to 20kg / cm 2 , and more specifically, 6kg / cm 2 Up to 10kg / cm 2 .

[0045] When the internal pressure of the absorption liquid degassing tower is less than 1kg / cm 2 When the internal pressure exceeds 20 kg / cm2, as described above, water may also be vaporized due to the high internal temperature of the absorption liquid degassing tower 5, and the degassing tower may not be able to perform the function of recovering and separating ammonia from the solution. On the other hand, when the internal pressure exceeds 20 kg / cm2, the absorption liquid degassing tower 5 may be degassing. 2 When the temperature is too high, the ammonia may need to be recovered and the energy cost may increase.

[0046] The removed ammonia may be captured at the upper end of the absorption liquid degassing tower 5, may be cooled by the cooler 8 at the upper end and rear end of the degassing tower, and may be provided to the first ammonia purification tower 10. The ammonia may be cooled to 20° C. to 50° C. by the cooler 8 at the upper end and rear end of the degassing tower.

[0047] Water from which ammonia has been degassed can be recovered from the lower end of the absorbing liquid degassing tower 5, can be cooled by the cooler 9 on the lower and rear ends of the degassing tower, can be provided to the ammonia absorption tower 2, and can be reused for absorbing ammonia in step S2.

[0048] Step S4 may be a step of purifying the removed ammonia, and impurity gases such as residual carbon dioxide, hydrogen sulfide and / or water vapor may be removed by step S4.

[0049] Step S4 is not limited to any specific example, as long as the method can separate the residual impurity gas from ammonia. For example, step S4 can be performed by membrane method, temperature swing adsorption, pressure swing adsorption, temperature swing pressure swing adsorption or distillation, and more preferably by distillation.

[0050] More specifically, when step S4 is performed by distillation, the input ammonia gas may be separated from residual impurity gases such as carbon dioxide, hydrogen sulfide, and water vapor by gas-liquid equilibrium at a specific temperature and pressure.

[0051] When step S4 is performed by distillation, the step may be performed by a purification tower, and a cooler may be provided on the upper end of the purification tower, a reboiler may be provided on the lower end, and a filler may be loaded therein.

[0052] In the purification tower, a gas-liquid equilibrium of ammonia may be formed at each stage formed by the filler, and in this case, ammonia gas and residual impurity gas may be separated from each other by the difference in boiling point and volatility of the mixed gas.

[0053] Step S4 can be performed through a plurality of steps.

[0054] More specifically, step S4 may include a primary purification step of removing residual carbon dioxide and sulfur dioxide gas from the ammonia gas degassed in step S3, and a secondary purification step of removing water or water vapor from the ammonia gas subjected to the primary purification step.

[0055] The primary purification step may include removing residual carbon dioxide and hydrogen sulfide using distillation, and the primary purification step may be performed by the first ammonia purification tower 10 .

[0056] More specifically, the primary purification step may further include a step of cooling the input ammonia gas; a step of removing gaseous residual impurity gas; and a step of reheating the ammonia gas from which the residual impurity gas has been removed, and the steps may be performed intermittently or continuously.

[0057] When the primary purification step is performed by distillation, the first ammonia purification tower 10 may further include a first ammonia purification tower cooler 11 and a first ammonia purification tower reboiler 12 .

[0058] The step of cooling the input ammonia gas may be performed by the cooler 11 of the first ammonia purification tower. The cooler 11 of the first ammonia purification tower may separate the ammonia gas from the input gas by sending the ammonia gas to the lower end of the first ammonia purification tower 10.

[0059] In addition, the step of reheating the ammonia gas from which the residual impurity gas has been removed may be performed by the reboiler 12 of the first ammonia purification tower. The reboiler 12 of the first ammonia purification tower may be performed by heating the ammonia gas to a temperature of 100 °C. 2 and H 2 S is sent to the upper part of the first ammonia purification tower 10 to convert CO 2 and H 2 S is separated from the input gas.

[0060] When the primary purification step is performed, the ammonia gas may be cooled to 0°C to 5°C, and more preferably to 0°C to 3°C, by the cooler 11 of the first ammonia purification tower.

[0061] When the temperature of the ammonia gas cooled by the cooler 11 of the first ammonia purification tower is lower than 0°C, there may be a problem that a large amount of energy may be consumed in the cooling process, which may increase the process cost, while on the other hand, when the temperature exceeds 5°C, the ammonia is not sufficiently cooled, so that there may be a problem that the amount of ammonia recovered to the lower end portion may be reduced.

[0062] In addition, when the primary purification step is performed by distillation, the pressure in the first ammonia purification tower 10 may be 1 kg / cm 2 Up to 20kg / cm 2 , and more specifically, 3kg / cm 2 Up to 10kg / cm 2 .

[0063] When the pressure in the first ammonia purification tower 10 is less than 1 kg / cm 2 When the pressure exceeds 20 kg / cm 2 When the distillation column is heated to 400 ℃ and the temperature is kept at 400 ℃, a large amount of energy may be required to reboil the lower end portion of the distillation column, which may reduce the economic efficiency.

[0064] The ammonia gas may be heated to 6° C. to 10° C. by the reboiler 12 of the first ammonia purification tower.

[0065] In the process that the input ammonia gas is cooled by the cooler 11 of the first ammonia purification tower and heated by the reboiler 12 of the first ammonia purification tower, ammonia having a relatively high boiling point can be recovered from the lower end of the first ammonia purification tower 10, and impurity gases having a relatively low boiling point such as CO 2 and H 2 S may be separated and removed in a gaseous state at the upper end of the first ammonia purification tower 10 .

[0066] The ammonia gas recovered from the first ammonia purification tower 10 may be input to the second ammonia purification tower to undergo a secondary purification step. Water or water vapor remaining in the ammonia gas may be removed through the secondary purification step.

[0067] The secondary purification step is not limited to any specific example as long as the method can separate water remaining in the ammonia gas, but more preferably, the step can be performed by distillation.

[0068] More specifically, the secondary purification step may further include a step of cooling the input ammonia gas; a step of removing liquid residual water; and a step of reheating the ammonia gas from which the residual water has been removed, and the steps may be performed intermittently or continuously.

[0069] When the secondary purification step is performed by distillation, the second ammonia purification tower 13 may further include a second ammonia purification tower cooler 14 and a second ammonia purification tower reboiler 15 .

[0070] Therefore, the step of cooling the input ammonia gas can be performed by the cooler 14 of the second ammonia purification tower. The cooler 14 of the second ammonia purification tower can separate residual water or water vapor from the input gas of the second ammonia purification tower 13 by sending water or water vapor to the lower end of the second ammonia purification tower 13.

[0071] In addition, the step of reheating the ammonia gas may be performed by the reboiler 15 of the second ammonia purification tower. The reboiler 15 of the second ammonia purification tower may separate the ammonia gas from the input gas of the second ammonia purification tower 13 by sending the ammonia gas to the upper end of the second ammonia purification tower 13.

[0072] When the secondary purification step is performed, the ammonia gas may be cooled to -35°C to 0°C, and more preferably to -10°C to -3°C, by the cooler 14 of the second ammonia purification tower.

[0073] When the temperature of the ammonia gas cooled by the cooler 14 of the second ammonia purification tower is lower than -35°C, the cooling process may consume a large amount of energy, which increases the process cost, and the water may be excessively cooled, so that ice may be formed, which may clog the pipeline. On the other hand, when the temperature exceeds 0°C, cooling may not be performed sufficiently to separate water from ammonia, so that impurities in the lower end portion may not be sufficiently removed, and thus ammonia of sufficient purity may not be recovered.

[0074] In addition, when the secondary purification step is performed by distillation, the pressure in the second ammonia purification tower 13 may be 1 kg / cm 2 Up to 20kg / cm 2 , and more specifically, 3kg / cm 2 Up to 10kg / cm 2 .

[0075] When the pressure in the second ammonia purification tower 13 is less than 1 kg / cm 2 When the pressure exceeds 20 kg / cm2, the separation ratio from impurities other than ammonia may be low and the ammonia purity may decrease, which may be problematic. 2 When the distillation column is heated to 400 ℃ and the temperature is kept at 400 ℃, a large amount of energy may be required to reboil the lower end portion of the distillation column, which may reduce the economic efficiency.

[0076] The temperature of the ammonia gas may be increased to 50° C. to 100° C., and more preferably to 55° C. to 70° C., by the reboiler 15 of the second ammonia purification column.

[0077] In the process that the input ammonia gas is cooled by the cooler 14 of the second ammonia purification tower and heated by the reboiler 15 of the second ammonia purification tower, ammonia with a relatively low boiling point can be recovered from the upper end of the second ammonia purification tower 13, and water with a relatively high boiling point can be separated and removed from the lower end of the second ammonia purification tower 13.

[0078] The ammonia gas purified through the secondary purification step may be cooled by the cooler 14 of the first ammonia purification tower, and may be recovered and stored.

[0079] The purity of ammonia purified, recovered, and stored in one embodiment of the present disclosure may be 99.0% or higher, more preferably 99.9% or higher, and even more preferably 99.99% or higher.

[0080] Embodiments of the invention

[0081] <Implementation Plan>

[0082] Hereinafter, embodiments of the present disclosure will be described. However, the embodiments of the present disclosure may be modified in various forms, and the scope of the present disclosure is not limited to the embodiments described below.

[0083] Figure 1 The figure shows the components of the ammonia recovery device according to the present disclosure and the connection relationship therebetween.

[0084] Figure 2 1 is a diagram illustrating a method for recovering ammonia, showing the flow of fluid streams ([A] to [S]) occurring during the implementation of the method for recovering ammonia according to the present disclosure.

[0085] Tables 1 and 2 below list Figure 2 The temperatures and pressures of the various fluid flows in the flow charts in FIG. 1 and FIG. 2, and the components and contents of the gases determined in the various flows. The flows A to S in Tables 1 and 2 may correspond to Figure 2 [A] to [S] in the table.

[0086] [Table 1]

[0087]

[0088] [Table 2]

[0089]

[0090] Reference Figure 1 , Figure 2 , Table 1 and Table 2, a step S1 is performed in which a mixed gas containing ammonia is pre-cooled by a mixed gas cooler 1 and supplied to an ammonia absorption tower 2.

[0091] In the ammonia absorption tower 2, step S2 is performed in which water supplied via the absorption liquid supply pump 3 is cooled by the absorption liquid cooler 4 and supplied to the ammonia absorption tower 2 to absorb ammonia.

[0092] In step S2, it can be determined that most of the carbon dioxide and sulfur dioxide are separated into the stream [D] without being dissolved in the water.

[0093] In the ammonia absorption tower 2, the water absorbing ammonia (ie, aqueous ammonia) is supplied to the absorption liquid degassing tower 5, and a step S3 of degassing ammonia gas from the aqueous ammonia is performed.

[0094] In this case, the water liquefied by the cooler 6 of the degassing tower is cooled by coolers on the lower and rear ends of the degassing tower and is supplied back to the ammonia absorption tower 2 and reused in step S2.

[0095] The removed ammonia gas is recooled through the coolers 8 at the upper and rear ends of the degassing tower, and is supplied to the first ammonia purification tower 10, and is subjected to the primary purification step of step S4.

[0096] The primary purification step is carried out by distillation and thus it is ensured that the carbon dioxide and sulphur dioxide gases partially dissolved in the water are separated into the stream [M] in step S2.

[0097] The ammonia gas having undergone the primary purification step is supplied to the second ammonia purification tower 13 and undergoes a secondary purification step.

[0098] A secondary purification step is carried out by distillation and it is thus determined that the residual water is partially separated into the stream [P].

[0099] It was confirmed that the ammonia purified through the S1 to S4 steps was recovered into the stream [O], and it was also confirmed that the purity of the ammonia was 99.99% or more.

[0100] It was determined that in the input mixed gas, carbon dioxide was removed at 99.8% (3284.1 kg / hour) of the input flow rate (3289.9 kg / hour), and sulfur dioxide was separated and removed to stream [4] in step S2 at 99.3% (1749.0 kg / hour) of the input flow rate (1760.8 kg / hour).

[0101] Therefore, in the case of the method of the present disclosure, it can be determined that 99% or more of carbon dioxide and sulfur dioxide in the input mixed gas are separated and removed in step S2, so that the possibility of carbon dioxide and sulfur dioxide forming salts in subsequent steps and causing pipeline contraction is significantly reduced.

[0102] [reference numerals]

[0103] 1: Mixed gas cooler

[0104] 2: Ammonia absorption tower

[0105] 3: Absorption liquid supply pump

[0106] 4: Absorption Liquid Cooler

[0107] 5: Absorption liquid degassing tower

[0108] 6: Cooler of degassing tower

[0109] 7: Reboiler of degassing tower

[0110] 8: Coolers at the upper and rear ends of the degassing tower

[0111] 9: Coolers at the lower and rear ends of the degassing tower

[0112] 10: The first ammonia purification tower

[0113] 11: Cooler of the first ammonia purification tower

[0114] 12: Reboiler of the first ammonia purification tower

[0115] 13: Second ammonia purification tower

[0116] 14: Cooler of the second ammonia purification tower

[0117] 15: Reboiler of the second ammonia purification tower

Claims

1. A method for recovering ammonia, the method comprising: include: Step S1 of providing a mixed gas containing ammonia; Step S2 of dissolving ammonia in water; Step S3 of degassing the ammonia water in which ammonia is dissolved to separate water and ammonia gas from each other; as well as The removed ammonia is subjected to purification step S4. 2 . The method according to claim 1 , wherein the step S1 further comprises the step of cooling the provided mixed gas to 5° C. to 80° C.

3. The method according to claim 1, wherein step S2 is performed by spraying water countercurrently to the flow of the mixed gas.

4. The method according to claim 3, wherein the temperature of the sprayed water is 5°C to 45°C. The method according to claim 1 , wherein the step S4 comprises a primary purification step and a secondary purification step.

6. The method according to claim 5, wherein the first purification step further comprises include: The step of cooling the ammonia gas; a step of removing residual impurity gases in a gaseous state; as well as A step of reheating the ammonia gas from which the residual impurity gas is removed.

7. The method according to claim 6, wherein during the primary purification step, the temperature is between 0°C and 5°C and the temperature is between 1 kg / cm 2 Up to 20kg / cm 2 The step of cooling the added ammonia gas is carried out under a pressure of .

8. The method according to claim 5, wherein the secondary purification step further comprises include: The step of cooling the ammonia gas; a step for removing liquid residue; as well as The ammonia gas from which the residues have been removed is subjected to a step of reheating.

9. The process according to claim 8, wherein the secondary purification step is carried out at a temperature of -35°C to 0°C and a pressure of 1 bar to 20 bar.

10. An ammonia recovery device, include: A mixed gas cooler (1), an ammonia absorption tower (2), an absorption liquid supply pump (3), an absorption liquid cooler (4), an absorption liquid degassing tower (5), a cooler (6) of the degassing tower, a reboiler (7) of the degassing tower, a cooler (8) at the upper end and the rear end of the degassing tower, a cooler (9) at the lower end and the rear end of the degassing tower, a first ammonia purification tower (10), a cooler (11) of the first ammonia purification tower, a reboiler (12) of the first ammonia purification tower, a second ammonia purification tower (13), a cooler (14) of the second ammonia purification tower, and a reboiler (15) of the second ammonia purification tower.

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