TWI773979B - Ammonia purification apparatus and purification method - Google Patents

Abstract

The invention provides an ammonia purification apparatus and purification method, including a heating and pressurizing unit, a first distillation unit, a first condensation unit, a second distillation unit, a second condensation unit, a storage tank unit, and a recycling unit. Through the design of double distillation unit and double condensation unit, crude ammonia with a concentration of 17 ~ 23% can be used as a raw material, and the purified ammonia gas with a purity greater than 5N can be obtained. In addition, with the arrangement of the recycling unit, the waste ammonia produced by the second distillation unit can be re-introduced into the recycling unit, and can be reheated and pressurized to be introduced into the first distillation unit as a raw material for recycling, which can be avoided due to the shortcomings of high concentration waste ammonia that needs to be diluted with water, and also achieve the purpose of circular economy.

Description

Ammonia water purification device and purification method

The present invention relates to a purification device and a purification method, in particular to an ammonia water purification device and a purification method.

Gases, such as NH ₃ (ammonia) gas, are currently used in the processes of the electronics industry or the semiconductor industry. For the advanced process, the purity requirement of the gas has been changed from 4N (99.99%) to 5N (99.999%), even up to 6N5 (99.99995% or more. The current technology for purifying NH ₃ is to select ammonia concentration of 99% to 99.99%) The most commonly used liquid ammonia is two towers, the first tower removes water, and the second tower removes gases that are lighter than ammonia such as N ₂ , O ₂ , and CH ₄ ; or the first tower removes water. The root tower removes gas that is lighter than ammonia, and the second tower removes water. Since water is an impurity that is difficult to remove, molecular sieves will be connected to the distillation tower for water removal so that the water can be below the specification to meet the requirements of semiconductor gases. Require.

As can be seen from the foregoing description, the prior art _of purifying NH at present is to select liquid-phase ammonia water with an ammonia concentration of 99% to 99.99% as the feed. However, the concentration of crude ammonia water in the face of circular economy is only 17%~23%. If the two types of distillation columns mentioned in the previous paragraph are used but there is no circulation unit, the old parameters are 17~23% for the feed. The change is not applicable, and the column diameter of the old water removal distillation column is too small relative to the column diameter required for the purification of crude ammonia water, so it cannot be used in 17~23% feed, and the concentration of waste ammonia water cannot reach the legal level. The standard of discharge, if it is to be discharged, it needs to be diluted with a large amount of water, which will waste too much water resources.

In addition, due to the extremely high concentration of ammonia water in the current purification of high-purity ammonia (the concentration of liquid phase feed is between 99% and 99.99%), in order to make the gas phase of the product reach 5N5 or 6N5 or more, the amount of ammonia in the waste ammonia water is extremely high. The concentration of ammonia will greatly exceed the emission standard of regulations. Therefore, it cannot be directly discharged. It must be stored separately or dealt with by other environmental protection manufacturers or used for other purposes.

Therefore, the purpose of the present invention is to provide an ammonia water purification device for purifying the crude ammonia water with a concentration of 17% to 23 mole%.

Therefore, the ammonia water purification device of the present invention includes a heating and pressurizing unit, a first distillation unit, a first condensation unit, a second distillation unit, a second condensation unit, a storage tank unit, and a recycling unit.

The heating and pressurizing unit is used for heating and pressurizing the crude ammonia water to form relatively high pressure crude ammonia water.

The first distillation unit includes a first distillation unit in communication with the heating and pressurizing unit A distillation column, and a boiling heater for heating the first distillation column, the relatively high-pressure crude ammonia water can enter the first distillation column for distillation to obtain the first mixed gas and the first discharged liquid.

The first condensing unit is used for condensing the first mixed gas, and includes a first condenser communicated with the first distillation column, and a first re-condensor located downstream of the first condenser.

The second distillation unit distills the condensed liquid obtained after passing through the first recondenser to generate the second mixed gas and high-concentration waste ammonia liquid, and includes a second distillation column communicated with the first recondenser, and a reboiler for heating the second distillation column.

The second condensing unit is used for condensing the second mixed gas after the second distillation, and includes a second condenser communicated with the second distillation column, and a second condenser sequentially located downstream of the second condenser A recondenser, and a subcooler that receives the liquid ammonia condensed by the second recondenser and forms a subcooled liquid.

The storage tank unit includes a fine storage tank communicating with the subcooler for storing liquid ammonia after passing through the subcooler.

The recirculation unit includes a gas-liquid storage tank, a heater, and a pressurized pump respectively communicated with the first distillation column and the second distillation column. The high-concentration ammonia liquid of the second distillation column is discharged into the second distillation column. Gas-liquid storage tank, the heater is used for heating the liquid in the gas-liquid storage tank to increase the pressure, so that it has roughly the same value as the crude ammonia water in the first distillation column and has a saturated gas-liquid two-phase, and the liquid phase in the gas-liquid storage tank can be reintroduced into the first distillation column.

The effect of the present invention is: through the innovative purification concept and the combined design of the simple device in this case, it can be applied to purify the crude ammonia water with a concentration of 17% to 23 mole% discharged from a semiconductor factory, and high purity (purity up to 5N) can be obtained. The ammonia gas above), and the concentration of waste ammonia water produced in the first distillation process can be directly discharged in compliance with government regulations, or recycled back to the process, and at the same time, the benefits of circular economy can be achieved.

2: pressurization unit

21: barrel tank

22: Pressurized pump

23: Pipeline

24: Pressure control valve

25: Temperature control valve

3: The first distillation unit

31: The first distillation column

32: Boil Heaters

4: The first condensing unit

41: First condenser

42: First Recondenser

5: Second distillation unit

51: Second distillation column

52: Reboiler

6: The second condensing unit

61: Second condenser

62: Second Recondenser

63: Subcooler

7: Tank unit

71: Boutique Storage Tank

72: Pressure control device

721: Manometer

722: Pressure relief valve

8: Recirculation unit

81: Gas-liquid storage tank

82: Heater

83: Pressurized pump

9: Gas absorption tank

M: flow adjustment unit

M1~M5: Flow control valve

91~9: Steps

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: FIG. 1 is a schematic diagram of an embodiment of the ammonia water purification device of the present invention; and FIG. 2 is the implementation of the ammonia water purification device of the present invention. Example of the process flow chart of the purification of ammonia water.

The ammonia water purification device of the present invention is used for purifying crude ammonia water with a concentration of 17 mole% to 23 mole%, and can obtain an ammonia water purification device with an ammonia gas concentration of more than 5N. Wherein, the source of the aforementioned crude ammonia water with a concentration of 17% to 23 mole% can be the ammonia water discharged from the semiconductor factory after dilution.

Referring to FIG. 1, an embodiment of the ammonia water purification device of the present invention includes a heating and pressurizing unit 2, a first distillation unit 3, a first condensation unit 4, a second distillation unit 5, a second condensation unit 6, A storage tank unit 7, a recirculation unit 8, a gas absorption tank 9, and a flow adjustment unit M.

The heating and pressurizing unit 2 is used to heat and pressurize the crude ammonia water with a concentration of 17 to 23%, so that the crude ammonia water can be formed into a relatively high-pressure crude ammonia water with a pressure greater than that of the crude ammonia water. It includes a tank 21 for accommodating a heat medium, a pressurized pump 22, a pipeline 23 arranged in the tank 21 to be heated by the heat medium, a pressure control valve 24, and a temperature control valve 25. Crude ammonia water can be fed into the pipeline 23 via the pressurized pump 22 and into the first distillation column 31 . Through the pressure control valve 24, the pressure of the crude ammonia water entering the first distillation column 31 through the pipeline 23 can be controlled, and the temperature control valve 25 can be used to adjust the heat medium flow in the tank 21 to control the crude ammonia in the pipeline 23. The temperature of the ammonia water makes the crude ammonia water reach the expected thermodynamic state and then enters the first distillation unit.

The first distillation unit 3 includes a first distillation column 31 communicating with the barrel tank 21 and the pipeline 23 of the heating and pressurizing unit 2 , and a first distillation column 31 adjacent to the bottom of the first distillation column 31 for the first distillation column 31 Heated boil heater 32 .

The relatively high-pressure crude ammonia water after passing through the heating and pressurizing unit can enter the first distillation column 31 through the pipeline 23, and the ammonia water can be boiled by the boiling heater 32, and the saturated gas phase flows above the distillation column and flows from the top of the distillation column. The liquid condensed by the condensed gas flows to the bottom of the tower for distillation to obtain the first mixed gas and the first discharged liquid. Furthermore, this A distillation column 31 can also re-introduce the first discharge liquid obtained by reflux and with high temperature into the barrel tank 21 through the pipeline as a heat source for heating the crude ammonia water in the pipeline 23, thereby saving energy.

The first condensing unit 4 is used for condensing the first mixed gas discharged after the first distillation, and includes a first condenser 41 communicated with the first distillation column 31 , and a first condenser 41 downstream of the first condenser 41 . The first recondenser 42 .

The second distillation unit 5 is in communication with the first condensation unit 4 and the recirculation unit 8, and is used for the second distillation of the condensed liquid obtained after passing through the first recondenser 42. In detail, the second distillation unit 5 includes a second distillation column 51 in communication with the first recondenser 42 and the recirculation unit 8, and a second distillation column 51 adjacent to the bottom of the second distillation column 51 to provide the second distillation column 51. The reboiler 52 for heating the substance (ammonia) in the distillation column 51. The ammonia water (condensed liquid) flowing to the bottom of the second distillation column 51 is heated through the reboiler 52, and is distilled in the second distillation column 51 to generate a second mixed gas and a high-concentration waste ammonia liquid at the bottom of the column. Wherein, the second mixed gas will be discharged into the second condensing unit 6 , and the waste ammonia liquid can be introduced into the recycling unit 8 through pipelines.

Since the detailed structures of the aforementioned first and second distillation towers 31 and 51 are well known in the technical field, they will not be further described. In addition, in this embodiment, the first and second heaters 32 and 52 are illustrated by taking heat exchange pipes as an example, but not limited thereto.

The second condensation unit 6 is communicated with the second distillation unit 5 for receiving and condensing the second mixed gas obtained after the second distillation, including a The column 51 is connected to a second condenser 61 for receiving and condensing the second mixed gas, a second recondenser 62 located downstream of the second condenser 61 in sequence, and a subcooler 63, the second The recondenser 62 is used for recondensing the gas discharged after passing through the second condenser 61 , and the subcooler 63 is used for subcooling the liquid ammonia obtained after passing through the second recondenser 62 condensed.

The storage tank unit 7 includes a fine storage tank 71 communicating with the subcooler 63 for storing liquid ammonia passing through the subcooler 63, and a pressure control device 72, which may have a pressure control device 72 for A pressure gauge 721 and a pressure relief valve 722 for detecting the pressure of the fine storage tank 71 are provided. The liquid ammonia has gas/liquid two phases when stored in the fine-quality storage tank 71 , and the storage tank unit 7 can control the pressure of the fine-quality storage tank 71 through the pressure control device 72 to prevent the pressure from being too high.

The recirculation unit 8 includes a gas-liquid storage tank 81 , a heater 82 , and a pressurized pump 83 . The gas-liquid storage tank 81 is connected to the first distillation column 31 , the second distillation column 51 and the gas absorption tank 9 respectively. Connected, wherein, the liquid (waste ammonia liquid) condensed and refluxed in the second distillation column 51 can be introduced into the gas-liquid storage tank 81, and the heater 82 and the pressurized pump 83 are provided for heating and pressurizing the gas-liquid storage tank 81. The liquid has approximately the same pressure as the crude ammonia water in the first distillation column 31 and has a gas phase and a liquid phase at the same time, and the liquid phase in the gas-liquid storage tank 81 can be reintroduced into the first distillation column 31 for concentration. Purified distillation operation, and the gas phase in the gas-liquid storage tank 81 can be discharged to the gas absorption tank 9 . In addition, it should be noted that the heater 82 of the recirculation unit 8 may also communicate with the first distillation column 31, And the first discharge liquid with high temperature obtained by refluxing the first distillation column 31 is introduced into the heater 82 (heat exchanger) as a partial heat source.

The gas absorption tank 9 communicates with the first recondenser 42 , the second recondenser 62 , the fine product storage tank 71 , and the gas-liquid storage tank 81 respectively, and is used for absorbing from the first and second recondensers 42 , 62 , the high-quality storage tank 71, and the gas (NH ₃ , H ₂ , N ₂ , O ₂ , CH ₄ , etc.) discharged from the gas-liquid storage tank 81 , and adjust the pressure of each barrel to avoid the danger of excessive pressure in the barrel , and has the purpose of purification and industrial safety.

The flow adjustment unit M may correspond to at least any of the aforementioned first and second distillation units 3 and 5, first and second condensing units 4 and 6, storage tank unit 7, recirculation unit 8 and gas absorption tank 9, depending on requirements. One is to set a flow regulating valve for regulating gas or liquid according to pressure or temperature, so as to regulate and control the flow rate of discharged gas or liquid. In this embodiment, the flow regulating unit M has a flow regulating valve M1 corresponding to the first distillation column 31 and a flow regulating valve M1 arranged between the first condenser 41 and the first recondenser 42 respectively. The valve M2, the flow regulating valve M3 arranged between the first recondenser 42 and the second distillation column 51, the flow regulating valve M4 arranged between the second condenser 61 and the second recondenser 62 , and the flow regulating valve M5 disposed between the second recondenser 62 and the subcooler 63 to adjust the gas and liquid entering the first recondenser 42, the second recondenser 62, and the subcooler 63 flow. However, it should be noted that, in actual implementation, the setting position of the flow adjustment unit M is not limited to this, and these devices may have other devices that are not shown, such as buffer buckets. connected to maintain a stable pressure flow.

Referring to FIGS. 1 and 2 in conjunction, the method for purifying crude ammonia water by using the embodiment of the ammonia water purification device of the present invention will be described as follows.

First, step 91 is performed, and the crude ammonia aqueous solution with a concentration of 17-23 mole% is heated under pressure.

In detail, the step 91 is to adjust the flow rate of the crude ammonia aqueous solution with a pressure/temperature of about 1 bar/20°C and a concentration of 17-23 mole% in an external storage tank through a flow control valve and use the pressurized aid to adjust the flow rate. Pu 22 is pressurized so that it becomes a crude ammonia solution with a pressure of about 4.4 bar and enters the pipeline 23, and then the pipeline 23 in which the crude ammonia flows is heated by the heating medium of the barrel 21, so that the crude ammonia solution is heated. The temperature reaches about 30 °C, and relatively high pressure crude ammonia water is obtained. The purpose of this step is to avoid the generation and flow of saturated steam in the pipeline 23 .

Next, step 92 is performed, and the relatively high-pressure crude ammonia water is introduced into the first distillation unit 3 for first distillation.

In detail, the step 92 is to introduce the relatively high-pressure crude ammonia water into the first distillation column 31, and use the boiling heater 32 located at the bottom of the first distillation column 31 to carry out the liquid flow in the first distillation column. Boil to form saturated gas and liquid (waste ammonia water) in the boiling tank. The saturated gas flows upward, and the liquid is discharged or reused for energy by the flow control valve M1. In the first distillation column 31, the gas-liquid two-phase flow is reversed, the liquid flows down, and the gas flows up, and heat transfer, mass transfer and phase leveling are carried out at the same time. balance. Therefore, the first mixed gas after the first distillation is discharged from the top of the first distillation column 31 and enters the first condenser 41 through a pipeline, while other gases are condensed and refluxed to the first distillation column 31 .

It should be noted that, the ammonia concentration of the first discharge liquid (ie, ammonia water waste liquid) can be controlled by the amount of the first mixed gas discharged from the top of the first distillation column 31, so that the concentration of the first discharge liquid can be controlled. The ammonia concentration is directly discharged in accordance with the government discharge specification or re-referenced to the process cycle application, and the discharge amount of the first discharged liquid is adjusted by the flow regulating valve M2, so as to meet the quality conservation.

In some embodiments, the ammonia concentration of the first discharge liquid can be controlled to be no greater than government discharge specifications. In some embodiments, the ammonia concentration of the first discharge liquid can be controlled below the discharge limit of government regulations and can be discharged directly.

In addition, it should be noted that, because the first discharge liquid obtained after distillation through the first distillation column 31 has a relatively high temperature, therefore, the first discharge liquid is circulated and introduced into the heating and pressurizing unit 2 It can save energy and have economic value.

Next, step 93 is performed, and the first mixed gas is condensed by the first condensation unit 4 .

Step 93 is to condense the first mixed gas entering the first condenser 41 first. The saturated gas obtained after condensation will be discharged to the first recondenser 42 for recondensation through the pipeline, and the liquid obtained after condensation through the first condenser 41 can be obtained by The line returns to the first distillation column 31 again.

Next, the saturated gas passing through the first condenser 41 and entering the first recondenser 42 is recondensed to obtain a condensed liquid and an exhaust gas. Wherein, the saturated gas can pass through the flow regulating valve M2 to control the gas flow entering the first re-condenser 42 , and the condensed liquid can be controlled by the flow regulating valve M3 and introduced into the second distillation column 51 through the flow regulating valve M3 . The exhaust gas of the first recondenser 42 contains impurities such as N ₂ , O ₂ , H ₂ and CH ₄ , and very little H ₂ O, which can be introduced into the gas absorption tank 9 through a pipeline.

Then, step 94 is performed again, and the condensed liquid is subjected to a second distillation by the second distillation unit 5 .

In detail, in step 94, the condensed liquid entering the second distillation column 51 from the second recondenser 42 is heated into a gas phase by the reboiler 52 at the bottom of the second distillation column 51 and then condensed to form a gas phase. Gas-liquid two-phase to concentrate and purify ammonia. The condensed second mixed gas (gas phase) is discharged from the top of the second distillation column 51 and enters the second condenser 61 through the pipeline, and is condensed and refluxed to the liquid phase at the bottom of the second distillation column 51 Because of the low water content, the high-concentration waste ammonia liquid cannot be directly discharged. Therefore, the high-concentration waste ammonia liquid can be returned to the heating gas-liquid storage tank 81 of the recirculation unit 8 through the pipeline, and the heater 82 and the The pressurized pump 83 makes this high-concentration waste ammonia liquid become a saturated gas liquid in the barrel tank 81, and after having a temperature and pressure approximately similar to the relatively high-pressure crude ammonia water entering the first distillation column 31, the barrel tank can be replaced. The saturated liquid in 81 is introduced into the The first distillation column 31 is again subjected to circulating distillation.

It should be noted that the ammonia molar concentration of the waste ammonia liquid of the second distillation column 51 is much higher than the discharge value regulated by government regulations, especially when the concentration of feed ammonia varies between 17 and 23 mole%, the bottom of the distillation column discharges The concentration change of the waste ammonia water will be very large, and the amount of ammonia discharged from the top of each distillation tower will be difficult to control. The limit is that the ammonia concentration is 99mole%~99.99mole% as the purification feed. In addition, if the waste ammonia liquid of the second distillation column 51 does not pass through the recycling unit 8 and then enters the first distillation column 31, the purity of the obtained ammonia gas will be greatly changed due to the change of the feed concentration, and In operation, it is necessary to adjust the size of the exhaust gas from time to time, which is not achieved by the conventional ammonia water purification device. Therefore, the present invention can maintain the second distillation through the recirculation unit 8, and the feed concentration is 17-23 mole%. The ammonia gas from the top of the tower 51 can reach a purity of more than 5N.

In this embodiment, the condensed and refluxed liquid phase from the bottom of the second distillation column 51 is introduced into the gas-liquid storage tank 81, and then heated and pressurized to 4.4 bar/60° C. A distillation column 31 concentrates and purifies, and the ammonia concentration of the saturated gas in the gas-liquid storage tank 81 is more than 90 mole%, and it can enter the gas absorption tank unit 9 again.

Next, step 95 is performed, and the second mixed gas is condensed by the second condensation unit 6 to obtain purified liquid ammonia.

In step 95, the second mixed gas entering the second condenser 61 is firstly Condensate. The saturated gas obtained after condensation will be discharged to the second recondenser 62 for recondensation through the pipeline, and the liquid obtained after condensation through the second condenser 61 can be refluxed to the second distillation column 51 through the pipeline. .

Next, the saturated gas passing through the second condenser 61 and entering the second recondenser 62 is recondensed to obtain a liquid ammonia and an exhaust gas. Wherein, the saturated gas can control the flow rate entering the second recondenser 62 through the flow regulating valve M4, the gas discharged from the second recondenser 62 can be introduced into the gas absorption tank 9 through the pipeline, and the liquid ammonia can be The flow into the subcooler 63 is controlled via a flow regulating valve M5. The subcooler 63 receives the refined and subcooled liquid ammonia obtained after being condensed by the second recondenser 62 .

Finally, step 96 is performed to store the refined liquid ammonia.

In step 96 , the purified and subcooled liquid ammonia obtained after passing through the subcooler 63 is introduced into the high-quality storage tank 71 through a pipeline to form a low-pressure gas-liquid two-phase ammonia liquid for storage. In addition, the pressure of the boutique storage tank 71 can be further monitored and adjusted through the pressure control device 72 . When the high-quality storage tank 71 is affected by the temperature of the environment and causes the pressure to exceed the set value, the pressure can be released through the pressure relief valve 722, and the gaseous ammonia in the high-quality storage tank 71 is discharged to the gas absorption tank 9 through the pipeline, In order to maintain the pressure of the boutique storage tank 71 .

In addition, it should be noted that the water content of the second mixed gas discharged after the second distillation is extremely low, and the impurity gas in the second mixed gas contains such as N ₂ , H ₂ , O ₂ , CH ₄ , therefore, in order to improve the purity of the final ammonia gas, the second mixed gas can be further discharged and distilled in the second condensing unit 62 (for detailed steps, please refer to TW I413891). The exhaust gas from the exhaust distillation can be reintroduced into the gas absorption tank 9 . In addition, the barrel tank 71 can also perform adiabatic exhaust distillation for higher purity, and the exhausted ammonia gas can enter the gas absorption tank 9 through the pressure relief valve 722 . In addition, after the ammonia water in the gas absorption tank 9 reaches a certain amount, it can also be diluted with water to form liquid ammonia with a concentration of 17-23%, and then introduced into the first distillation column 31 for concentration and purification cycle.

The present invention passes through the composition design of double distillation towers (first, second distillation units 3, 5) and double condensation units (first and second condensation units 4, 6), therefore, the available concentration is 17 ~ 23 mole% of crude ammonia water is The raw material is purified to obtain ammonia with a purity greater than 5N, and the most creatively conceived recycling unit 8 in this case is used, so that the waste ammonia water of the second distillation column 51 can be re-introduced into the recycling unit 8, so that the reheating can reach the required level. At the same pressure, gas-liquid two-phase is formed in the barrel of unit 81, and the liquid phase is re-introduced into the first distillation column 31 as a raw material for recycling, which can avoid the disadvantage that high-concentration waste ammonia liquid needs to be diluted and discharged with water. In addition, by controlling the amount of mixed gas discharged from the first distillation unit 3, the ammonia concentration of the first discharged liquid can be controlled, so that the ammonia concentration of the first discharged liquid can be directly discharged in compliance with regulations without adding water for dilution. Furthermore, the present invention also utilizes the first discharge liquid obtained by refluxing the first distillation unit 3 to be circulated to the heating and pressurizing unit 2 and the recirculation unit 8 to serve as the heater of the heating and pressurizing unit 2. 23 and/or part of the heat source of the heater 82 of the recirculation unit 8 can be used to save energy and achieve cycle Therefore, the purpose of the present invention can indeed be achieved.

However, the above are only examples of the present invention, and should not limit the scope of implementation of the present invention. Any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the patent specification are still included in the scope of the present invention. within the scope of the invention patent.

2: pressurization unit

21: barrel tank

22: Pressure Pump

23: Pipeline

3: The first distillation unit

31: The first distillation column

32: Boil Heaters

4: The first condensing unit

41: First condenser

42: First Recondenser

5: Second distillation unit

51: Second distillation column

52: Reboiler

6: The second condensing unit

61: Second condenser

62: Second Recondenser

63: Subcooler

7: Tank unit

71: Boutique Storage Tank

72: Pressure control device

721: Manometer

722: Pressure relief valve

8: Recirculation unit

81: Gas-liquid storage tank

82: Heater

83: Pressurized pump

9: Gas absorption tank

M: flow adjustment unit

M1~M6: Flow control valve

Claims (10)

A kind of ammonia water purification device, is used for purifying the thick ammonia water that concentration is between 17～23 mole%, comprises: a heating and pressurizing unit, is used for this thick ammonia water heating and pressurizing to make this thick ammonia water form pressure is greater than the relative high pressure of this thick ammonia water Crude ammonia water; a first distillation unit, including a first distillation column communicated with the heating and pressurizing unit, and a boiling heater for heating the first distillation column, the first distillation column can be used for the relatively high pressure crude Ammonia water is distilled to obtain a first mixed gas and a first discharge liquid; a first condensation unit for condensing the first mixed gas, including a first condenser communicated with the first distillation column, and a first condenser located in the first A first recondenser downstream of the condenser; a second distillation unit for distilling the condensed liquid obtained after passing through the first recondenser to produce a second mixed gas and waste ammonia liquid, including a a second distillation column communicated with the first recondenser, and a reboiler for heating the second distillation column; a second condensing unit for condensing the second mixed gas, including a second distillation column communicated with the second distillation column a second condenser, and a second re-condenser sequentially located downstream of the second condenser, and a sub-cooler, the sub-cooler receives the liquid ammonia obtained after condensation by the second re-condenser and forms subcooled liquid; a storage tank unit including a fine storage tank in communication with the subcooler for storing liquid ammonia passing through the subcooler; and A recirculation unit, including a gas-liquid storage tank, a heater, and a pressurized pump respectively communicated with the first distillation column and the second distillation column, and the waste ammonia liquid of the second distillation column will be introduced into the gas-liquid The storage tank, the heater and the pressurized pump supply the liquid heating of the gas-liquid storage tank to increase the pressure, so that it has approximately the same pressure as the crude ammonia water in the first distillation column and has a saturated gas-liquid two-phase, And the liquid phase in the gas-liquid storage tank can be reintroduced into the first distillation column. The ammonia water purification device according to claim 1, further comprising a gas absorption tank communicating with the gas-liquid storage tank of the recycling unit for absorbing the ammonia gas discharged from the gas-liquid storage tank. The ammonia water purification device according to claim 2, wherein the fine product storage tank of the storage tank unit is communicated with the gas absorption tank, and the storage tank unit further includes a pressure control device for controlling the pressure of the fine product storage tank. The ammonia water purification device according to claim 2, wherein the gas absorption tank is also communicated with the first re-condenser, the second re-condenser, and the fine-quality storage tank for absorption from the first re-condenser, the second re-condenser Recondenser, and the gas discharged from the fine storage tank. The ammonia water purification device according to claim 1, wherein the heating and pressurizing unit comprises a barrel for accommodating a heat medium, a pressurized pump, and a barrel that is accommodated in the barrel and can be heated by the heat The first distillation unit is communicated with the barrel tank, and the first discharge liquid is discharged into the barrel tank and used as the heat medium. The ammonia water purification device according to claim 1, wherein the first distillation unit The first discharge liquid of 100 is in communication with the recirculation unit and serves as part of the heat source for the recirculation unit. A method for purifying ammonia water, comprising: introducing a crude ammonia solution with a concentration of 17 to 23 mole% into a first distillation unit after being heated and pressurized by a heating and pressurizing unit, and performing first distillation to obtain a first mixed gas and a first discharge liquid; use a first condensation unit to condense the first mixed gas to obtain a condensed liquid and a discharge gas; introduce the condensed liquid into a second distillation column for the second distillation to obtain a second Mix gas and waste ammonia liquid, and return the waste ammonia liquid to a gas-liquid storage tank of a recycling unit through a pipeline, and the liquid in the gas-liquid storage tank can be reintroduced into the first distillation tower, wherein the recycling unit It includes a gas-liquid storage tank, a heater and a pressurized pump, and the method also includes: using the heater and the pressurized pump of the recirculation unit to heat the liquid in the gas-liquid storage tank to increase the pressure, so that it has The same pressure as the crude ammonia water in the first distillation column is introduced into the first distillation column; the second mixed gas is introduced into a second condensing unit for condensation to obtain high-pressure subcooled refined liquid ammonia; and the Refined liquid ammonia is introduced into a fine storage tank for storage. The ammonia water purification method according to claim 7, further comprising: introducing the first discharge liquid into at least one of the heating and pressurizing unit or the recycling unit, and using it as a heat medium source. The ammonia water purification method as claimed in claim 7, wherein the ammonia water purification device further comprises a gas absorption tank respectively communicated with the gas-liquid storage tank, the first condensing unit, the second condensing unit, and the fine-quality storage tank. The purification method also includes introducing the gas discharged from any one of the gas-liquid storage tank, the first condensation unit, the second condensation unit, and the fine-quality storage tank into the gas absorption tank through a pipeline. The ammonia water purification method according to claim 9, further comprising: after diluting the ammonia water in the gas absorption tank to the same concentration as the crude ammonia water, introducing it into the heating and pressurizing unit through a pipeline.

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