WO2013185412A1 - 氨和二氧化碳混合气体的分离方法 - Google Patents

氨和二氧化碳混合气体的分离方法 Download PDF

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Publication number
WO2013185412A1
WO2013185412A1 PCT/CN2012/079416 CN2012079416W WO2013185412A1 WO 2013185412 A1 WO2013185412 A1 WO 2013185412A1 CN 2012079416 W CN2012079416 W CN 2012079416W WO 2013185412 A1 WO2013185412 A1 WO 2013185412A1
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Prior art keywords
ammonia
carbon dioxide
separation column
water
column
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PCT/CN2012/079416
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English (en)
French (fr)
Inventor
唐印
龚元德
刘朝慧
雷林
李旭初
宋国天
陈辉
孔杰
李忠云
Original Assignee
北京烨晶科技有限公司
四川金象赛瑞化工有限责任公司
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Publication of WO2013185412A1 publication Critical patent/WO2013185412A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/02—Preparation, purification or separation of ammonia
    • C01C1/12—Separation of ammonia from gases and vapours
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/002—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by condensation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/50—Carbon dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B01D2257/406—Ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/50—Carbon oxides
    • B01D2257/504—Carbon dioxide
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/40—Capture or disposal of greenhouse gases of CO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Definitions

  • the invention belongs to the field of gas separation, and particularly relates to a method for separating a mixed gas of ammonia and carbon dioxide.
  • FIG. 1 is a schematic illustration of an isobaric phase diagram of the system.
  • the three vertices of the triangle represent ammonia, carbon dioxide, and water, respectively called ammonia, carbon, and water.
  • Curve III is referred to as the liquid-phase top ridge line and represents the azeotrope.
  • the area at the upper left of curve III is called the I zone, which is the ammonia debris zone, and the zone at the lower right of curve III is called the zone II, the carbon dioxide fraction.
  • the dotted line IV is called a crystal line, and the right and upper sides are gas-liquid-solid three-phase coexistence areas.
  • the composition of the remaining liquid phase moves toward and finally reaches the liquidus top ridge line;
  • the ammonia carbon aqueous solution which is located in the II zone is steamed
  • the composition of the remaining liquid phase also shifts to and finally reaches the liquidus top ridge line;
  • the aqueous ammonia carbon solution which is composed on the liquid ridge line III is vaporized, gas phase and
  • the mass ratio of ammonia to carbon dioxide in the liquid phase is the same, that is, ammonia carbon separation cannot be performed. If the distillation is continued, the liquid phase composition moves along the liquid ridge line to the water angle until the liquid phase becomes pure water.
  • One of the methods includes: (1) sending the mixed gas to the ammonia separation column to remove the separated ammonia gas; (2) feeding the liquid containing ammonia gas, carbon dioxide, and water remaining after the step (1) a carbon dioxide separation tower for removing the separated carbon dioxide; (3) feeding the liquid containing ammonia gas, carbon dioxide and water remaining after the separation in step (2) to the analytical tower, and extracting the ammonia-containing gas, carbon dioxide and water vapor
  • the gas is returned to the ammonia separation column for separation.
  • the bottom operating temperature of the ammonia separation column is 60-170 ° C
  • the bottom operating temperature of the carbon dioxide separation column is 75-200 ° C
  • the operating pressure of the carbon dioxide separation column does not exceed Double the ammonia separation tower.
  • Cipheral Patent Document CN101862577A discloses a method for recovering carbon dioxide and liquid ammonia by using melamine tail gas, which comprises: (1) feeding an ammonia carbon mixture into an carbon dioxide separation tower as an aqueous solution, the bottom of the tower is indirectly heated by steam, and the top of the tower is separated and contained.
  • decarbonized ammonia water is obtained at the bottom of the tower;
  • the decarbonized ammonia water is introduced into the water separation tower, and is thoroughly analyzed by heating, and the analytical water obtained at the bottom of the tower is cooled and cooled, and sent to the above-mentioned trimeric atmosphere.
  • the amine production device is used as the absorption water of the ammonia-carbon mixed gas, and the analytical gas is obtained at the top of the column;
  • the above-mentioned analytical gas is finely dried in the ammonia purification tower, and pure ammonia gas is obtained from the top of the tower, and is separated from the bottom of the tower.
  • the aqueous ammonia solution containing carbon dioxide is returned to the carbon dioxide separation column.
  • the above-mentioned prior art method for separating ammonia carbon has a drawback in that the above method requires a large amount of steam to be heated in the carbon dioxide separation column, and the energy consumption is large.
  • the ammonia-carbon mixed gas is first absorbed by water and then sent to the carbon dioxide separation column as an aqueous solution, in order to promote the absorption of ammonia carbon, it is necessary to first consume energy to remove the heat of dissolution of ammonia gas and carbon dioxide, etc. After the ammonia carbon solution enters the carbon dioxide separation tower, it needs to consume energy again.
  • the carbon dioxide is distilled from the liquid phase, which further increases the energy consumption of the separation system, and P strives to lower the economic efficiency of the separation process.
  • the carbon dioxide separation tower requires a large amount of steam for heating, and the energy consumption is large, especially in the prior art, when the ammonia carbon mixed gas is first absorbed by water and then sent to the carbon dioxide separation tower as an aqueous solution.
  • the ammonia carbon mixed gas is first absorbed by water and then sent to the carbon dioxide separation tower as an aqueous solution.
  • it is necessary to first consume energy to remove the heat of dissolution of the ammonia gas and the carbon dioxide.
  • After the ammonia carbon aqueous solution enters the carbon dioxide separation tower it is necessary to consume energy to evaporate the carbon dioxide from the liquid phase, further increasing the separation.
  • the present invention provides a separation method for ammonia and carbon dioxide gas which can greatly reduce the amount of steam and thereby reduce the energy consumption of the system.
  • a method for separating a mixed gas of ammonia and carbon dioxide comprising:
  • step b the aqueous solution of ammonia carbon in step b is sent to a water separation column for desorption, most of the ammonia, carbon dioxide and a part of water in the aqueous solution of ammonia carbon are distilled off, and the remaining aqueous solution containing almost no ammonia and carbon dioxide from the water The bottom of the separation tower is separated;
  • step c The ammonia, carbon dioxide and water distilled in step c are sent to an ammonia separation column, and ammonia gas is separated from the top of the ammonia separation column.
  • the ammonia and carbon dioxide mixed gas is subjected to sectional compression, and the mixed gas is cooled by spraying a cooling liquid into the mixed gas between the stages.
  • a dilute aqueous solution of ammonia is separated from the side line of the water separation column, and the aqueous solution of diluted ammonia is used as a circulating aqueous solution in a carbon dioxide separation column.
  • the cooling liquid is an aqueous solution of dilute ammonia solution separated from a side line of the water separation column or an aqueous solution containing almost no ammonia and carbon dioxide separated from the bottom of the water separation column or a tower from the ammonia separation column.
  • the operating pressure of the carbon dioxide separation column is 15-25 bar, and the operating temperature of the column is 155-186 ° C.
  • the operating pressure of the carbon dioxide separation column is 18 bar, and the operating temperature of the column is 165-171 °C.
  • the ammonia separation column has an operating pressure of 2-18 bar, and the column operating temperature is 60-140 ° C.
  • the operating pressure of the ammonia separation column is 2-4 bar, and the operating temperature of the column is 60-85 °C.
  • the top of the water separation column is provided with a reflux condenser, which is an air cooler.
  • a circulation pump and a circulation cooler are disposed at a lower portion and/or a middle portion of the ammonia separation column.
  • the circulating cooler of the ammonia separation column is an air cooler.
  • An aqueous solution containing ammonia and carbon dioxide obtained from the bottom of the ammonia separation column is returned to the carbon dioxide separation column for use as a circulating aqueous solution.
  • An aqueous solution of dilute ammonia solution separated from the side line of the water separation column is fed from the middle and/or the lower portion of the carbon dioxide separation column.
  • An aqueous solution separated from the bottom of the water separation column is fed from the top of the carbon dioxide separation column.
  • the aqueous solution separated from the bottom of the water separation column is cooled and then fed from the top of the carbon dioxide separation column.
  • a method for separating a mixed gas of ammonia and carbon dioxide according to the present invention for a mixed gas of ammonia and carbon dioxide Compress one or more stages to raise the pressure to 15 ⁇ 25bar.
  • the conventional method is to first absorb the ammonia-carbon mixed gas with water to form an aqueous solution of ammonia carbon.
  • the aqueous ammonia carbon solution is then sent to a carbon separation column to separate the carbon dioxide, or sent to an ammonia separation column to separate the ammonia gas.
  • ammonia-carbon mixture When the ammonia-carbon mixture is absorbed by water, a large amount of heat of dissolution is not utilized, and a large amount of circulating cooling water is used to remove the heat of dissolution; and when the aqueous ammonia solution is sent to a carbon separation column to separate carbon dioxide, or sent to an ammonia separation column for separation. In the case of ammonia, a large amount of energy is consumed to heat the aqueous ammonia solution to desorb carbon dioxide or ammonia.
  • the invention compresses the ammonia carbon mixture gas to 15 ⁇ 25 bar and then sends it to the carbon separation tower to separate carbon dioxide.
  • the advantages are: in the carbon separation tower, the carbon dioxide is already in a gaseous state and does not need to be desorbed; the large amount of heat released when the gaseous ammonia is absorbed by the water is directly absorbed by the water or ammonia aqueous solution in the tower from the top to the bottom, thereby greatly reducing the amount of heat.
  • the steam consumption of the reboiler almost all of the electrical energy consumed by the compressor is converted into the internal energy ( ⁇ ) of the exhaust gas.
  • the compressed exhaust gas is equal to the exhaust gas before compression.
  • the electric energy that is, the electric energy consumed by the compressor is not lost, but is taken into the carbon separation tower and utilized.
  • a method for separating a mixed gas of ammonia and carbon dioxide according to the present invention wherein a mixed gas of ammonia and carbon dioxide is subjected to sectional compression, and the mixed gas is cooled by a spray cooling method between stages.
  • the sensible heat of the compressed gas is converted into latent heat, and the total enthalpy of the material remains unchanged, that is, the energy is not lost during the cooling process, and if the indirect cooling method is used, it is not only compressed. The enthalpy of the gas is reduced and additional energy is consumed to deliver the cooling medium.
  • a method for separating a mixed gas of ammonia and carbon dioxide according to the present invention wherein the carbon dioxide separation column has an operating pressure of 15 to 25 bar and an operating temperature of 160 to 190 °C.
  • the invention provides optimum operating conditions based on the isobaric phase diagrams of ammonia, carbon dioxide and water. Operation within the above pressure and temperature ranges can improve the separation efficiency of the carbon dioxide separation column and reduce the energy consumption of the operating system.
  • the operating pressure of the carbon dioxide separation column of the present invention is 15-25 bar. The pressure has a great influence on the shape of the ridge line in the ternary isobaric phase diagram of NH3 - C02 - H20.
  • the ratio to carbon dioxide is also larger, but when the pressure exceeds 25 bar and continues to rise, the tendency to shift to the left is getting smaller and smaller, so the operating pressure of the carbon dioxide separation column is preferably 15-25 bar.
  • the invention sets the operating temperature of the top of the carbon dioxide separation tower to control the ammonia content in the carbon dioxide gas to be lower than 50 pm
  • the operation pressure of the carbon dioxide separation column is 18 bar
  • the operating temperature of the bottom of the carbon dioxide separation column is 165 to 171 ° C
  • the operating temperature of the column top is 70 to 90 °C.
  • the CO2 separation column is operated at a pressure of 18 bar, it is operated in a suitable operating zone with a column temperature of approximately 165-171 °C. If the temperature is lower than 165 V, the liquid-phase ammonia-carbon ratio becomes smaller, the separation efficiency decreases, the carbon dioxide circulating in the system increases, and the energy consumption increases. If the temperature continues to rise from nrc, the ammonia content in the liquid phase rapidly decreases. The water content increases rapidly, but since the total amount of ammonia discharged from the bottom of the carbon dioxide separation column does not change, this means that the circulation amount of water is greatly increased, and thus the energy consumption is also greatly increased.
  • a method for separating a mixed gas of ammonia and carbon dioxide according to the present invention wherein the operating pressure of the ammonia separation column is 2 to 18 bar.
  • the operating temperature of the column is 60-140 ° C.
  • the mass of ammonia and carbon dioxide in the liquid phase is relatively small, the separation efficiency of the ammonia column is high, and the boiling point of the liquid phase and the melting point of ammonium amino citrate (crystal line IV) Maintaining an appropriate safety distance avoids the formation of agglomerates and affects operation. Therefore, the ammonia tower operates in this area, which is not only stable in operation but also low in energy consumption.
  • the aqueous solution separated from the bottom of the water separation column is used as a circulating aqueous solution in a carbon dioxide separation column, and is separated from the bottom of the water separation column
  • the resulting aqueous solution is fed from the upper portion of the carbon dioxide separation column because the purity of the water fed to the top of the carbon dioxide separation column is relatively high (e.g., its ammonia content should be 0.2%) so that the carbon dioxide gas is distilled from the top of the carbon dioxide separation column.
  • the ammonia content is 50 pm, and the aqueous solution separated from the bottom of the water separation column contains almost no ammonia, and is therefore suitable for use as circulating water at the top of the carbon dioxide separation column.
  • a method for separating a mixed gas of ammonia and carbon dioxide according to the present invention which is separated from a side line of the water separation column
  • the aqueous solution of diluted ammonia is used as a circulating aqueous solution in a carbon dioxide separation column, and the aqueous solution of diluted aqueous ammonia is fed from the middle and/or the lower portion of the carbon dioxide separation column.
  • all of the water required for the carbon separation column comes from the bottom of the water separation column.
  • the relatively high purity water added to the top of the carbon separation tower is from the bottom of the water separation tower, so that the ammonia content of the carbon dioxide distilled from the top of the carbon separation tower is 50 pm, and the water fed to the lower part of the carbon separation tower is
  • the ammonia produced from the side line of the water separation column contains a small amount of a dilute aqueous solution of dilute ammonia. Since this part of the water is about 70% to 90% of the water added to the carbon separation tower, after the side line of the water separation tower is produced, the load of the water separation tower is greatly reduced, and the energy consumption is greatly reduced.
  • Figure 1 shows the isobaric phase diagram of the ternary system of ammonia, carbon dioxide and water
  • FIG. 2 is a flow chart showing a method for separating a mixed gas of ammonia and carbon dioxide according to the present invention
  • Figure 3 is a flow chart showing a method for separating ammonia and carbon dioxide mixed gas when the operating pressure of the ammonia separation column of the present invention is 18 bar;
  • Figure 4 is a flow chart showing the separation process of the mixed gas of ammonia and carbon dioxide in the prior art.
  • FIG. 2 The process flow of the method for separating ammonia and carbon dioxide mixed gas described in this embodiment is shown in FIG. 2, and the separation method is as follows:
  • the melamine tail gas with a pressure of 4 bar is sent to the end of the exhaust gas compressor for compression.
  • the outlet pressure is 8.6 bar
  • the temperature is raised to 236 ° C
  • the temperature is sprayed into the diluted ammonia carbon solution produced by the side line of the water separation tower 5.
  • Drop to 140 ° C then send to the second section of the compressor 2 to continue compression, the gas is compressed to 18bar, 234 ° C.
  • the compressed gas is sent to the bottom of the carbon dioxide separation column 3, and the upper, middle and lower portions of the carbon dioxide separation column 3 are respectively fed with water from the bottom of the water separation column 5, and the diluted carbon ammonia produced from the side line of the water separation column 5.
  • the operating pressure of the carbon dioxide separation column 3 is 18 bar, the temperature at the top of the column is 70 to 90 ° C, the temperature of the column is 165 to 170 ° C; the carbon dioxide gas having an ammonia content of 50 ppm is discharged from the top of the carbon dioxide separation column 3, and the carbon carbon containing a small amount of carbon dioxide The aqueous solution is discharged from the bottom of the column.
  • the aqueous ammonia carbon solution containing a small amount of carbon dioxide discharged from the bottom of the carbon dioxide separation column 3 is sent to the water separation column 5 through the heat exchanger 8 and the heat exchanger 7.
  • a reboiler 9 is attached to the bottom of the water separation tower 5, and the antiseptic air enters the water separation tower 5 through the reboiler 9;
  • a reflux condenser 11 is disposed at the top of the water separation tower 5, and the reflux condenser 11 is an air cooler;
  • a side line production pump 6 is provided in the middle of the tower 5.
  • the operating pressure of the water separation column 5 is about 2 bar, the outlet temperature of the reflux condenser 11 is 68 to 74 ° C, and the temperature of the column is 117 to 121 °C.
  • the dilute aqueous ammonia solution produced by the side line of the water separation tower is sent to the carbon dioxide separation tower 3 and the outlet pipe of the exhaust gas compressor section 1; the water produced at the bottom is boosted by the booster pump 17, and the heat exchanger 10 and the cooler 12 are cooled. Thereafter, it is sent to the top of the carbon dioxide separation column 3 and the top of the inerting tower 23, and the cooler 12 is an air cooler, ammonia, A mixed gas of carbon dioxide and water is distilled off from the top of the water separation column.
  • a mixture of ammonia, carbon dioxide and water distilled from the top of the water separation column 5 is sent to the bottom of the ammonia separation column 16.
  • the circulating ammonia water is fed from the top of the ammonia separation column 16, and a reflux condenser 26 is attached to the top of the ammonia separation column 16, and a circulation pump 14 and a circulation cooler 13 are attached in the middle, and the circulation cooler 13 is an air cooler.
  • the operating pressure of the ammonia separation column 16 is 2 bar
  • the outlet temperature of the reflux condenser 26 is 48 to 53 ° C
  • the temperature of the column is 60 to 71 °C.
  • the concentrated aqueous ammonia solution produced at the bottom of the ammonia separation column 16 is sent to the carbon dioxide separation column 3 through the booster pump 15, the heat exchanger 10, and the heat exchanger 7, and the ammonia gas is separated from the top portion of the ammonia separation column 16.
  • FIG. 2 The process flow of the method for separating ammonia and carbon dioxide mixed gas described in this embodiment is shown in FIG. 2, and the separation method is as follows:
  • the melamine tail gas with a pressure of 4 bar is sent to the tail gas compressor for a period of 1 to be compressed.
  • the outlet pressure is 7.8 bar
  • the temperature is raised to 213 °C
  • the temperature is sprayed into the dilute ammonia solution produced by the side line of the water separation tower 5. Dropped to 140 ° C. Then send it to the second section of the compressor 2 and continue to compress, compressing the gas to 15 bar, 223 °C.
  • the compressed gas is sent to the bottom of the carbon dioxide separation column 3, and the upper, middle and lower portions of the carbon dioxide separation column 3 are respectively fed with water from the bottom of the water separation column 5, and the diluted carbon ammonia produced from the side line of the water separation column 5.
  • a reboiler 4 is attached to the bottom of the carbon dioxide separation column 3, and the antiseptic air enters the carbon dioxide separation column 3 through the reboiler 4.
  • the operating pressure of the carbon dioxide separation column 3 is 15 bar, the temperature at the top of the column is 70 80 ° C, and the temperature in the column is 155 to 161 °C.
  • Carbon dioxide gas having an ammonia content of 50 ppm is discharged from the top of the carbon dioxide separation column 3; an aqueous solution of ammonia carbon containing a small amount of carbon dioxide is discharged from the bottom of the column.
  • the aqueous solution of ammonia carbon containing a small amount of carbon dioxide discharged from the bottom of the carbon dioxide separation column 3 is sent to the water separation column 5 through the heat exchanger 8 and the heat exchanger 7.
  • a reboiler 9 is attached to the bottom of the water separation tower 5, and the antiseptic air enters the water separation tower 5 through the reboiler 9;
  • a reflux condenser 11 is disposed at the top of the water separation tower 5, and the reflux condenser 11 is an air cooler;
  • a side line production pump 6 is provided in the middle of the tower 5.
  • the operating pressure of the water separation column 5 is about 2 bar, the outlet temperature of the reflux condenser 11 is 68 to 74 ° C, and the temperature of the column is 117 to 121 °C.
  • the dilute aqueous solution of ammonia produced by the side line of the water separation tower 5 is sent to the carbon dioxide separation tower 3 and the outlet pipe of the exhaust gas compressor 1; the water produced at the bottom is boosted by the booster pump 17, and the heat exchanger 10 and the cooler 12 are cooled. Thereafter, they are sent to the top of the carbon dioxide separation column 3 and the top of the inerting column 23, the cooler 12 is an air cooler, and a mixed gas of ammonia, carbon dioxide and water is distilled off from the top of the water separation column 5.
  • a mixture of ammonia, carbon dioxide and water distilled from the top of the water separation column 5 is sent to the bottom of the ammonia separation column 16.
  • the circulating ammonia water is fed from the top of the ammonia separation column 16, and a reflux condenser 26 is attached to the top of the ammonia separation column 16, and a circulation pump 14 and a circulation cooler 13 are attached in the middle, and the circulation cooler 13 is an air cooler.
  • the operating pressure of the ammonia separation column 16 is 2 bar
  • the outlet temperature of the reflux condenser 26 is 48 to 53 ° C
  • the temperature of the column is 60 to 71 °C.
  • the concentrated aqueous ammonia solution produced at the bottom of the ammonia separation column 16 is sent to the carbon dioxide separation column 3 through the booster pump 15, the heat exchanger 10, and the heat exchanger 7, and the ammonia gas is separated from the top portion of the ammonia separation column 16.
  • FIG. 2 The process flow of the method for separating ammonia and carbon dioxide mixed gas described in this embodiment is shown in FIG. 2, and the separation method is as follows:
  • the melamine tail gas with a pressure of 4 bar is sent to the end of the exhaust gas compressor for compression.
  • the outlet pressure is lO. lbar, and the temperature is raised to 257 ° C.
  • After being sprayed into the dilute ammonia solution produced by the side line of the water separation tower 5 The temperature dropped to 140 °C. Then, it is sent to the second section of the compressor. 2 Continue to compress and compress the gas to 25 bar and 258 °C.
  • the compressed gas is sent to the bottom of the carbon dioxide separation column 3, and the upper, middle and lower portions of the carbon dioxide separation column 3 are respectively fed with water from the bottom of the water separation column 5, and the diluted carbon ammonia produced from the side line of the water separation column 5.
  • a reboiler 4 is attached to the bottom of the carbon dioxide separation column 3, and the antiseptic air enters the carbon dioxide separation column 3 through the reboiler 4.
  • the operating pressure of the carbon dioxide separation column 3 is 25 bar, and the temperature at the top of the tower is 80 90 °C, the temperature of the tower is 180 ⁇ 186 °C.
  • Carbon dioxide gas having an ammonia content of 50 ppm is discharged from the top of the carbon dioxide separation column 3; an aqueous solution of ammonia carbon containing a small amount of carbon dioxide is discharged from the bottom of the column.
  • the aqueous solution of ammonia carbon containing a small amount of carbon dioxide discharged from the bottom of the carbon dioxide separation column 3 is sent to the water separation column 5 through the heat exchanger 8 and the heat exchanger 7.
  • the bottom of the water separation tower 5 is provided with a reboiler 9, and the antiseptic air enters the water separation tower 5 through the reboiler 9.
  • a reflux condenser 11 is provided at the top of the water separation column 5, the reflux condenser 11 is an air cooler, and a side line production pump 6 is disposed at the center of the water separation tower 5.
  • the operating pressure of the water separation column 5 is about 2 bar, the outlet temperature of the reflux condenser 11 is 68 to 74 ° C, and the temperature of the column is 117 to 121 °C.
  • the dilute aqueous solution of ammonia produced by the side line of the water separation tower 5 is sent to the carbon dioxide separation tower 3 and the outlet pipe of the exhaust gas compressor 1; the water produced at the bottom is boosted by the booster pump 17, and the heat exchanger 10 and the cooler 12 are cooled. Thereafter, they are sent to the top of the carbon dioxide separation column 3 and the top of the inerting column 23, the cooler 12 is an air cooler, and a mixed gas of ammonia, carbon dioxide and water is distilled off from the top of the water separation column 5.
  • a mixture of ammonia, carbon dioxide and water distilled from the top of the water separation column 5 is sent to the bottom of the ammonia separation column 16.
  • the circulating ammonia water is fed from the top of the ammonia separation column 16, and a reflux condenser 26 is attached to the top of the ammonia separation column 16, and a circulation pump 14 and a circulation cooler 13 are attached in the middle, and the circulation cooler 13 is an air cooler.
  • the operating pressure of the ammonia separation column 16 is 2 bar
  • the outlet temperature of the reflux condenser 26 is 48 to 53 ° C
  • the temperature of the column is 60 to 71 °C.
  • the concentrated aqueous ammonia solution produced at the bottom of the ammonia separation column 16 is sent to the carbon dioxide separation column 3 through the booster pump 15, the heat exchanger 10, and the heat exchanger 7, and the ammonia gas is separated from the top portion of the ammonia separation column 16.
  • the melamine tail gas with a pressure of 4 bar is sent to the tail gas compressor for a period of 1 to be compressed.
  • the outlet pressure is 8.6 bar
  • the temperature is raised to 234 ° C
  • the temperature is sprayed into the diluted aqueous ammonia solution produced by the side line of the water separation tower 5. Dropped to 140 ° C. Then, it is sent to the second stage of the compressor. 2 Continue to compress and compress the gas to 18 bar and 234 °C.
  • the compressed gas is sent to the bottom of the carbon dioxide separation column 3, and the upper, middle and lower portions of the carbon dioxide separation column 3 are respectively fed with water from the bottom of the water separation column 5, and the diluted carbon ammonia produced from the side line of the water separation column 5.
  • a reboiler 4 is attached to the bottom of the carbon dioxide separation column 3, and the antiseptic air enters the carbon dioxide separation column 3 through the reboiler 4.
  • the operating pressure of the carbon dioxide separation column 3 is 18 bar, the temperature at the top of the column is 70 90 ° C, and the temperature in the column is 165 to 170 ° C.
  • Carbon dioxide gas having an ammonia content of 50 ppm is discharged from the top of the carbon dioxide separation column 3; an aqueous solution of ammonia carbon containing a small amount of carbon dioxide is discharged from the bottom of the column.
  • the aqueous solution of ammonia carbon containing a small amount of carbon dioxide discharged from the bottom of the carbon dioxide separation column 3 is sent to the water separation column 5 through the heat exchanger 8 and the heat exchanger 7.
  • the bottom of the water separation tower 5 is provided with a reboiler 9, and the antiseptic air enters the water separation tower 5 through the reboiler 9.
  • a reflux condenser 11 is provided at the top of the water separation column 5, the reflux condenser 11 is an air cooler, and a side line production pump 6 is disposed at the center of the water separation tower 5.
  • the operating pressure of the water separation column 5 is about 4 bar, the outlet temperature of the reflux condenser 11 is 85 to 95 ° C, and the temperature of the column is 138 to 143.5 °C.
  • the dilute aqueous solution of ammonia produced by the side line of the water separation tower 5 is sent to the carbon dioxide separation tower 3 and the outlet pipe of the exhaust gas compressor 1; the water produced at the bottom is boosted by the booster pump 17, and the heat exchanger 10 and the cooler 12 are cooled. Thereafter, they are sent to the top of the carbon separation column and the top of the inerting column 23, the cooler 12 is an air cooler, and a mixed gas of ammonia, carbon dioxide and water is distilled off from the top of the water separation column 5.
  • a mixture of ammonia, carbon dioxide and water distilled from the top of the water separation column 5 is sent to the bottom of the ammonia separation column 16.
  • the circulating ammonia water is fed from the top of the ammonia separation column 16, and a reflux condenser 26 is attached to the top of the ammonia separation column 16, and a circulation pump 14 and a circulation cooler 13 are attached in the middle, and the circulation cooler 13 is an air cooler.
  • the operating pressure of the ammonia separation column 16 is 4 bar
  • the outlet temperature of the reflux condenser 26 is 55 to 62 ° C
  • the temperature of the column is 75 to 85 ° C.
  • the concentrated aqueous ammonia solution produced at the bottom of the ammonia separation column 16 is sent to the carbon dioxide separation column 3 through the booster pump 15, the heat exchanger 10, and the heat exchanger 7, and the ammonia gas is separated from the top portion of the ammonia separation column 16.
  • Example 5 The process of the separation method of the mixed gas of ammonia and carbon dioxide described in this embodiment is shown in FIG. 3, and the operating pressures of the carbon separation tower, the water separation tower and the ammonia separation tower are both 18 bar, and the ammonia gas separated by the ammonia separation tower is used.
  • the ammonia gas condenser using water as a cooling medium is condensed into liquid ammonia. Methods as below:
  • the melamine tail gas with a pressure of 4 bar is sent to the tail gas compressor for a period of 1 to be compressed.
  • the outlet pressure is 8.6 bar
  • the temperature is raised to 234 ° C
  • the temperature is sprayed into the diluted aqueous ammonia solution produced by the side line of the water separation tower 5. Dropped to 140 ° C. Then, it is sent to the second stage of the compressor. 2 Continue to compress and compress the gas to 18 bar and 234 °C.
  • the compressed gas is sent to the bottom of the carbon dioxide separation column 3, and the upper, middle and lower portions of the carbon dioxide separation column 3 are respectively fed with water from the bottom of the water separation column 5, and the diluted carbon ammonia produced from the side line of the water separation column 5.
  • a reboiler 4 is attached to the bottom of the carbon dioxide separation column 3, and the antiseptic air enters the carbon dioxide separation column 3 through the reboiler 4.
  • the operating pressure of the carbon dioxide separation column 3 is 18 bar, the temperature at the top of the column is 70 90 ° C, and the temperature in the column is 165 to 170 ° C.
  • Carbon dioxide gas having an ammonia content of 50 ppm is discharged from the top of the carbon dioxide separation column 3; an aqueous solution of ammonia carbon containing a small amount of carbon dioxide is discharged from the bottom of the column.
  • the aqueous solution of ammonia carbon containing a small amount of carbon dioxide discharged from the bottom of the carbon dioxide separation column 3 is pumped by the pump 27, sent to the water separation column 5 via the heat exchanger 8 and the heat exchanger 7.
  • the bottom of the water separation tower 5 is provided with a reboiler 9, and the antiseptic air enters the water separation tower 5 through the reboiler 9.
  • the top of the water separation column 5 is provided with a reflux condenser 11, which is an air cooler, and a side line production pump 6 is disposed at the center of the water separation column 5.
  • the operating pressure of the water separation column 5 is about 18 bar, the outlet temperature of the reflux condenser 11 is 137 142 ° C, and the temperature of the column is 200 206 °C.
  • the dilute ammonia carbon aqueous solution collected on the side line of the water separation tower 5 is sent to the carbon dioxide separation tower 3 and the exhaust gas compressor section 1 outlet pipe; the water collected at the bottom is cooled by the pump 17, the heat exchanger 7 and the cooler 12, and sent to the respective The top of the carbon separation column 3 and the top of the idler column 23, the cooler 12 is an air cooler, and a mixed gas of ammonia, carbon dioxide and water is distilled off from the top of the water separation column 5.
  • a mixture of ammonia, carbon dioxide and water distilled from the top of the water separation column 5 is sent to the bottom of the ammonia separation column 16.
  • the circulating ammonia water is fed from the top of the ammonia separation column 16, and a reflux condenser 26 is attached to the top of the ammonia separation column 16, and a circulation pump 14 and a circulation cooler 13 are attached in the middle, and the circulation cooler 13 is an air cooler.
  • the operating pressure of the ammonia separation column 16 is 18 bar
  • the outlet temperature of the reflux condenser 26 is 42 to 45 ° C
  • the temperature of the column is 97 140 °C.
  • the concentrated aqueous ammonia solution produced at the bottom of the ammonia separation column 16 is sent to the carbon dioxide separation column 3 via the pump 15, and ammonia gas is separated from the top of the ammonia separation column 16.
  • the ammonia gas separated at the top of the ammonia separation column 16 enters the ammonia gas condenser 22, and the ammonia gas is condensed into liquid ammonia, and the inert gas which is not condensed is sent to the idler column 23.
  • the idling tower 23 is provided with a circulation pump 25 and a circulation chiller 24, and the makeup water and the circulating water are fed to the top of the lavatory tower 23.
  • the ammonia content after washing is 30 ppm of inert gas is discharged into the atmosphere from the top of the column, and the ammonia water at the bottom of the column is sent to the ammonia separation column 16.
  • the ammonia gas separated from the top of the ammonia separation column 16 in the embodiment 1-4 is sent to the screw compressor for compression, and the compressed ammonia gas enters the partial condenser 19 to cool to 44 to 46 ° C, and the condensed liquid is partially.
  • the inlet pipe is sent to and injected into a section, and the remaining liquid is sent to the ammonia separation column 16.
  • the gas from the partial condenser 19 enters the second stage of the screw compressor and continues to be compressed to 18 bar, and then enters the partial condenser 21 to cool to 45 to 47 ° C.
  • a part of the condensed liquid is sent to and injected into the inlet tube of the second section 20 of the screw compressor.
  • the remaining liquid is sent to the ammonia separation column 16.
  • the gas from the partial condenser 21 enters the ammonia condenser 22, the ammonia gas is condensed into liquid ammonia, and the uncondensed inert gas is sent to the idle scrubber 23.
  • the idling tower 23 is provided with a circulation pump 25 and a circulation chiller 24, and the makeup water and the circulating water are fed to the top of the lavatory tower 23. After the washing, the ammonia content of 30 ppm of the inert gas is discharged into the atmosphere from the top of the column, and the ammonia water at the bottom of the column is sent to the ammonia separation column.
  • the trimeric amine tail gas is compressed by means of two-stage compression. Alternatively, it may be compressed in a single stage or more than two stages.
  • the separation method described in the present invention is applicable not only to the trimeric amine tail gas, but also to ammonia, carbon dioxide and the ammonia gas and carbon dioxide mass ratio of any ratio between 0.5 and 1.5 and a water content of 15%. Separation of mixed gas of water. Comparative example
  • the separation method used in the comparative example is a conventional separation method of ammonia-carbon mixed gas, and the flow thereof is as shown in FIG. 4:
  • a melamine tail gas mixed gas having a pressure of 4 bar is first sent to a tail gas absorption tower for absorption by circulating water to form an aqueous ammonia carbon solution; the unabsorbed inert gas is vented.
  • the aqueous solution of ammonia carbon is sent to a carbon dioxide separation tower.
  • the operating pressure of the carbon dioxide separation column is 18 bar, the temperature at the top of the column is 70 to 90 ° C, and the temperature of the column is 165 to 170 ° C.
  • the carbon dioxide gas is separated from the top of the carbon separation column; an aqueous solution of ammonia carbon containing a small amount of carbon dioxide is taken from the bottom of the carbon separation tower.
  • the mixed gas of ammonia, carbon dioxide and water distilled in the step (3) is sent to the bottom of the ammonia separation column, and the circulating ammonia water is added to the top of the column.
  • the operating pressure of the ammonia tower is 2 bar
  • the temperature at the top of the column is 48-53 ° C
  • the temperature of the column is 66-71 ° C.
  • the ammonia gas is separated from the top of the ammonia separation column, and is obtained from the bottom of the ammonia separation tower.
  • the aqueous solution containing ammonia and carbon dioxide is pressurized by a booster pump and returned to the carbon dioxide separation column for use as a circulating aqueous solution.
  • the ammonia gas in the comparative example was compressed and condensed by the ammonia gas compression process in the example to obtain liquid ammonia.

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Abstract

一种氨和二氧化碳混合气体的分离方法，该方法首先对氨和二氧化碳混合气体进行压缩，使压力升至15-25bar后再送入二氧化碳分离塔（3），然后再依次进入水分离塔（5）和氨分离塔（16）；从水分离塔（5）的侧线分离出稀氨碳水溶液；将混合气体的压缩分为多段，段间冷却采用直接喷液冷却法；采用空冷器代替以循环冷却水为冷却介质的冷却器。

Description

氨和二氧化碳混合气体的分离方法
技术领域
本发明属于气体分离领域， 具体涉及氨和二氧化碳混合气体的分离方法。
背景技术
在合成尿素以及用尿素合成三聚氰胺的过程中会产生大量含氨、 二氧化碳的混合气 体， 为了进一步利用气体中的氨和二氧化碳， 通常要对气体进行分离。
氨、 二氧化碳、 水三元系统的相平衡关系十分复杂， 它不遵循拉烏尔定律， 只能用根 据实验数据作出的相图来表示。 附图一是一张该系统的等压相图的示意图。 三角形的三个 顶点分别代表氨、 二氧化碳和水， 分别称为氨角、 碳角、 水角。 曲线 III称为液相顶脊线， 代表共沸混合物。 曲线 III左上方的区域称为 I区即氨精榴区， 曲线 III右下方的区域称为 II 区即二氧化碳精榴区。 虚线 IV称为结晶线， 其右、 上方为气液固三相共存区。 当组成位于 I区的氨碳水溶液进行蒸镏时， 随着氨气的不断蒸出， 剩余液相的组成移向并最后到达液 相顶脊线； 当组成位于 II区的氨碳水溶液进行蒸镏时， 随着二氧化碳气的不断蒸出， 剩余 的液相的组成也移向并最后到达液相顶脊线； 对组成位于液相顶脊线 III上的氨碳水溶液进 行蒸镏， 气相和液相的氨与二氧化碳的质量比相同， 即无法进行氨碳分离。 若继续蒸镏， 则液相组成沿液相顶脊线向水角移动， 直至液相成为纯水为止。
已知的氨碳混合物的分离方法如 #释法（ dilution process )、 差压法（ pressure differential process )等， 都以上述氨、 二氧化碳、 水三元系统的等压相图为理论基础， 这些方法都包 括下列三个部分： 在相图的 I区操作的氨分离部分、 在相图的 II区操作的二氧化碳分离部 分、 在相图的液相顶脊线 III上操作的解吸部分（水分离部分）。 对于氨和二氧化碳的分离 次序， 当氨碳水溶液的组成位于相图的氨精镏区时， 则此混合物首先被引入氨分离区进行 分离， 如美国专利文献 US4163648公开了分离氨气和二氧化碳的方法， 其中一种方法包 括： （ 1 )将混合气体送入氨分离塔， 将分离出的氨气移出； （ 2 )将经步骤（ 1 分离后剩 余的含有氨气、 二氧化碳和水的液体送入二氧化碳分离塔， 将分离出的二氧化碳移出； ( 3 )将经步骤（2 )分离后剩余的含有氨气、 二氧化碳和水的液体送入解析塔， 将解析出 的含氨气、 二氧化碳和水蒸汽的气体再返回氨分离塔进行分离。 上述方法中， 氨分离塔的 底部操作温度为 60-170°C , 二氧化碳分离塔的底部操作温度为 75-200°C , 二氧化碳分离塔 的操作压力不超过氨分离塔的两倍。
除了上述首先进入氨分离区进行分离的工艺外， 若氨碳水溶液的组成位于相图的碳精 镏区时， 则此混合物首先被引入碳分离塔进行分离。 如中国专利文献 CN101862577A公开 了一种利用三聚氰胺尾气回收二氧化碳和液氨的方法， 包括： （ 1 )将氨碳混合物以水溶液 形式送入二氧化碳分离塔， 塔底用蒸汽间接加热， 塔顶分离出含有 5%水蒸气的二氧化碳 气体， 塔底得到脱碳氨水； （2 )将上述脱碳氨水进入水分离塔， 经加热彻底解析， 塔底得 到的解析水， 经冷却降温， 送往上述三聚氛胺生产装置用作氨碳混合气体的吸收水， 塔顶 得到解析气； （ 3 )将上述解析气在氨精镏塔内经精镏干燥， 从塔顶得到纯氨气体， 从塔底 分离出的含有二氧化碳的氨水溶液再返回二氧化碳分离塔。
但上述现有技术中氨碳分离的方法存在的缺陷在于， 上述方法在二氧化碳分离塔需要 耗费大量的蒸汽进行加热， 能耗较大。 尤其是对于现有技术中先将氨碳混合气体用水进行 吸收， 再以水溶液形式送入二氧化碳分离塔时， 为了促进氨碳的吸收， 需要先消耗能量将 氨气和二氧化碳的溶解热移出， 等氨碳水溶液进入二氧化碳分离塔后， 还需要再消耗能量 将二氧化碳从液相中蒸出来， 这就进一步增加了分离系统的能耗， P争低了分离工艺的经济 效益。
发明内容
为了解决现有技术中二氧化碳分离塔需要耗费大量的蒸汽进行加热， 能耗较大， 尤其 是对于现有技术中先将氨碳混合气体用水进行吸收， 再以水溶液形式送入二氧化碳分离塔 时， 为了促进氨碳混合气体的吸收， 需要先消耗能量将氨气和二氧化碳的溶解热移出， 等 氨碳水溶液进入二氧化碳分离塔后， 还需要再消耗能量将二氧化碳从液相中蒸出来， 进一 步增加分离系统能耗的问题。 本发明提供了一种能够大幅度降低蒸汽用量， 从而降低系统 能耗的氨和二氧化碳气体的分离方法。
本发明所述的氨和二氧化碳气体的分离方法的技术方案为：
一种氨和二氧化碳混合气体的分离方法， 包括：
a. 对氨和二氧化碳混合气体进行压缩， 使压力升至 15-25bar;
b. 将压缩后的气体送入二氧化碳分离塔， 向所述二氧化碳分离塔送入循环水溶液， 从所述二氧化碳分离塔的塔顶分离出二氧化碳气体， 从所述二氧化碳分离塔的塔底得到含 少量二氧化碳的氨碳水溶液；
c 将步骤 b中的氨碳水溶液送入水分离塔进行解吸， 所述氨碳水溶液中的大部分氨、 二氧化碳和一部分水被蒸出， 剩余的几乎不含氨和二氧化碳的水溶液从所述水分离塔的塔 底分离出来；
d. 将步骤 c中蒸出的氨、 二氧化碳和水送入氨分离塔， 从所述氨分离塔的塔顶分离出 氨气。
所述步骤 a中， 对氨和二氧化碳混合气体进行分段压缩， 并在段间向所述混合气体中 喷冷却液对所述混合气体进行冷却。
从所述水分离塔的侧线分离出稀氨碳水溶液， 所述稀氨碳水溶液用作二氧化碳分离塔 中的循环水溶液。
所述冷却液为从所述水分离塔的侧线分离出的稀氨碳水溶液或者从所述水分离塔的塔 底分离出的几乎不含氨和二氧化碳的水溶液或者从所述氨分离塔的塔底分离出的含氨、 二 氧化碳的水溶液。
所述二氧化碳分离塔的操作压力为 15-25bar, 塔釜操作温度为 155-186°C
所述二氧化碳分离塔的操作压力为 18bar, 塔釜操作温度为 165-171 °C
所述氨分离塔的操作压力为 2-18bar, 塔釜操作温度为 60-140°C
所述氨分离塔的操作压力为 2-4bar, 塔釜操作温度为 60-85 °C
所述水分离塔的顶部设置有回流冷凝器， 所述回流冷凝器为空冷器。
所述氨分离塔的下部和 /或中部设置有循环泵和循环冷却器。
所述氨分离塔的循环冷却器是空冷器。
从所述氨分离塔的塔底得到的含氨、 二氧化碳的水溶液返回所述二氧化碳分离塔用作 循环水溶液。
从所述水分离塔的侧线分离出的稀氨碳水溶液从所述二氧化碳分离塔的中部和 /或下 部送入。
从所述水分离塔的塔底分离出来的水溶液从所述二氧化碳分离塔的顶部送入。
从所述水分离塔的塔底分离出来的水溶液经冷却后再从所述二氧化碳分离塔的顶部送 入。
本发明所述的氨和二氧化碳混合气体的分离方法的优点在于：
( 1 )本发明所述的氨和二氧化碳混合气体的分离方法， 对氨和二氧化碳混合气体进行 一段或者多段压缩， 使压力升至 15~25bar。 传统方法是先用水吸收氨碳混合气体， 生成氨 碳水溶液。 然后将氨碳水溶液送入碳分离塔分离二氧化碳， 或送入氨分离塔分离氨气。 在 用水吸收氨碳混合气时， 大量溶解热不但得不到利用， 还要用大量循环冷却水将溶解热移 出； 而当氨碳水溶液送入碳分离塔分离二氧化碳， 或送入氨分离塔分离氨气时， 又要消耗 大量能量去加热氨碳水溶液， 以便将二氧化碳或氨解吸出来。
本发明将氨碳混合气压缩至 15~25bar后送入碳分离塔去分离二氧化碳。 其优点是： 在碳分离塔内， 二氧化碳已经是气态， 不需要解吸； 气态的氨被水吸收时放出的大量热量 直接被塔内自上而下流的水或氨碳水溶液吸收， 从而大大减少了再沸器的蒸汽耗量； 压缩 机所消耗的电能几乎全部转化为尾气的内能（焓） ， 压缩后的尾气与压缩前的尾气相比， 其焓的增加值约等于压缩机所消耗的电能， 即： 压缩机所消耗的电能并没有损失， 而是被 带入碳分离塔， 得到了利用。
( 2 )本发明所述的氨和二氧化碳混合气体的分离方法， 对氨和二氧化碳混合气体进行 分段压缩， 并在段间使用喷液冷却法对所述混合气体进行冷却。 与现有技术中惯用的间接 冷却法相比其优点在于， 压缩气体的显热转化为潜热， 物料的总焓值保持不变， 即降温过 程中能量没有损失， 若采用间接冷却法， 则不但压缩气体的焓值减少， 还要消耗额外的能 量来输送冷却介质。
( 3 )本发明所述的氨和二氧化碳混合气体的分离方法， 所述二氧化碳分离塔的操作压 力为 15-25bar, 操作温度为 160-190°C。 本发明以氨、 二氧化碳、 水的等压相图为依据， 给出了最佳的操作条件， 在上述压力和温度范围内操作可提高二氧化碳分离塔的分离效 率、 降低操作系统的能耗。 本发明设置二氧化碳分离塔的操作压力为 15-25bar。 压力对 NH3 - C02 - H20三元等压相图中顶脊线的形状影响较大， 压力越高顶脊线的下半段越向 左偏， 位于该处顶脊线上的液相的氨与二氧化碳的比值也越大， 但当压力超过 25bar继续 升高时， 向左偏的趋势越来越小， 所以二氧化碳分离塔的操作压力以 15-25bar为宜。
本发明设置二氧化碳分离塔塔顶的操作温度控制二氧化碳气体中氨的含量低于 50pm
此外， 本发明还进一步优选所述二氧化碳分离塔的操作压力为 18bar, 所述二氧化碳 分离塔塔底的操作温度为 165-171 °C , 塔顶的操作温度为 70-90°C。 当二氧化碳分离塔操作 压力为 18bar 时， 在适宜操作区内操作， 塔釜温度约在 165-171 °C之间。 若温度低于 165 V , 则液相氨碳比变小， 分离效率下降、 在系统中循环的二氧化碳增多， 能耗增大； 若温 度从 nrc继续升高， 液相中氨含量迅速减小、 水含量迅速增大， 但由于从二氧化碳分离 塔底部排出的氨的总量不变， 这意味着水的循环量大大增加， 因而能耗也大大增加。
( 4 )本发明所述的氨和二氧化碳混合气体的分离方法， 所述氨分离塔的操作压力为 2-18bar。 塔釜操作温度为 60-140°C , 在该范围内操作， 液相的氨与二氧化碳的质量比较 小， 氨塔的分离效率高， 且液相沸点与氨基曱酸铵的熔点 （结晶线 IV )保持适当的安全距 离， 可避免生成结.晶， 影响操作， 因此氨塔在该区域内操作， 不但操作稳定， 而且能耗 也较低。
( 5 )本发明所述的氨和二氧化碳混合气体的分离方法， 从所述水分离塔的塔底分离出 来的水溶液用作二氧化碳分离塔中的循环水溶液， 从所述水分离塔的塔底分离出来的水溶 液从所述二氧化碳分离塔的上部送入， 原因在于送入二氧化碳分离塔顶部的水的纯度要求 比较高 （如其氨含量应 0.2% ) , 以便使二氧化碳分离塔顶蒸出的二氧化碳气体中氨的含 量 50pm, 而从所述水分离塔的塔底分离出来的水溶液几乎不含氨， 因此适于用作二氧 化碳分离塔顶部的循环水。
( 6 )本发明所述的氨和二氧化碳混合气体的分离方法， 从所述水分离塔的侧线分离出 的稀氨碳水溶液用作二氧化碳分离塔中的循环水溶液， 所述稀氨碳水溶液从所述二氧化碳 分离塔的中部和 /或下部送入。 在传统的氨碳分离方法中， 碳分离塔所需的水全部来自水 分离塔塔底。 本发明只有加入碳分离塔顶部的纯度比较高的水来自水分离塔的底部， 以便 使碳分离塔顶蒸出的二氧化碳的氨含量 50pm, 而送入碳分离塔中、 下部的水， 则是来 自水分离塔侧线采出的氨含少量的稀氨碳水溶液。 由于这部分水约为加入碳分离塔的水的 70%~90%, 改由水分离塔侧线采出后， 水分离塔的负荷大大减轻、 能耗大大减少。
( 7 )本发明所述的氨和二氧化碳混合气体的分离方法， 水分离塔的回流冷凝器、 水分 离塔塔底采出液冷却器、 氨分离塔的循环冷却器等， 均采用空气冷却器， 在传统的氨碳分 离方法中， 当热流体需要冷却时， 一般均采用以循环冷却水为冷却介质的冷却器。 本发明 所述的方法中， 使循环冷却水的用量大大减少。
附图说明
为了使本发明所述的技术方案更加便于理解， 下面结合附图和具体实施方式对本发明 所述的技术方案做进一步的阐述。
图 1所示是氨、 二氧化碳、 水三元系统的等压相图；
图 2所示是本发明所述的氨和二氧化碳混合气体的分离方法的流程图；
图 3所示是本发明所述的氨分离塔操作压力为 18bar时氨和二氧化碳混合气体分离方 法的流程图；
图 4所示是现有技术中氨和二氧化碳混合气体的分离工艺流程图。
其中， 附图标记为：
1-压缩机一段； 2-压缩机二段； 3-二氧化碳分离塔； 4、 9-再沸器； 5-水分离塔； 6-侧 线采出泵； 7， 8， 10-换热器； 11， 26-回流冷凝器； 12-冷却器； 13， 24-循环冷却器； 14 , 25-循环泵； 15， 17, 27 -升压泵； 16-氨分离塔； 18-螺杆压缩机一段； 19， 21-分凝 器； 20-螺杆压缩机二段； 22-氨气冷凝器； 23-惰洗塔。
具体实施方式
实施例 1
本实施例中所述的氨和二氧化碳混合气体的分离方法的工艺流程如图 2所示， 所述的 分离方法为：
a.将压力为 4bar 的三聚氰胺尾气送入尾气压缩机一段 1 进行压缩， 一段出口压力为 8.6bar, 温度升至 236°C , 喷入由水分离塔 5侧线采出的稀氨碳水溶液后温度降至 140°C , 然后再送入压缩机二段 2继续压缩， 将气体压缩至 18bar、 234°C。
b.将压缩后的气体送入二氧化碳分离塔 3底部， 二氧化碳分离塔 3的上、 中、 下部分 别送入来自水分离塔 5塔底的水、 来自水分离塔 5侧线采出的稀氨碳水溶液和来自氨分离 塔 16底部的浓氨碳水溶液的混合液； 二氧化碳分离塔 3底部附有再沸器 4， 防腐空气经再 沸器 4进入二氧化碳分离塔 3。 二氧化碳分离塔 3的操作压力为 18bar, 塔顶温度 70~90 °C , 塔釜温度 165~170°C ; 氨含量 50ppm的二氧化碳气体从二氧化碳分离塔 3的塔顶排 出， 含少量二氧化碳的氨碳水溶液从塔底排出。
c 从二氧化碳分离塔 3塔底排出的含少量二氧化碳的氨碳水溶液经换热器 8和换热器 7后送入水分离塔 5。 水分离塔 5底部附有再沸器 9, 防腐空气经再沸器 9进入水分离塔 5; 水分离塔 5的顶部设置有回流冷凝器 11 , 所述回流冷凝器 11为空冷器； 水分离塔 5的中 部设置有侧线采出泵 6。 水分离塔 5的操作压力约为 2bar， 回流冷凝器 11出口温度 68~74 °C , 塔釜温度 117~121 °C。 水分离塔侧线采出的稀氨碳水溶液分别送往二氧化碳分离塔 3 和尾气压缩机一段 1的出口管； 底部采出的水经升压泵 17升压、 换热器 10和冷却器 12 冷却后分别送往二氧化碳分离塔 3顶部和惰洗塔 23顶部， 所述冷却器 12为空冷器， 氨、 二氧化碳和水的混合气体从水分离塔的顶部蒸出。
d. 水分离塔 5顶部蒸出的氨、 二氧化碳和水的混合气体送往氨分离塔 16底部。 从氨 分离塔 16顶部送入循环的氨水， 氨分离塔 16顶部附有回流冷凝器 26, 中部附有循环泵 14 和循环冷却器 13 , 所述循环冷却器 13为空冷器。 氨分离塔 16的操作压力为 2bar, 回流冷 凝器 26出口温度 48~53 °C , 塔釜温度 60~71 °C。 氨分离塔 16底部采出的浓氨碳水溶液经 升压泵 15、 换热器 10、 换热器 7后送入二氧化碳分离塔 3， 从所述氨分离塔 16的顶部分 离出氨气。
实施例 2
本实施例中所述的氨和二氧化碳混合气体的分离方法的工艺流程如图 2所示， 所述的 分离方法为：
a.将压力为 4bar 的三聚氰胺尾气送入尾气压缩机一段 1 进行压缩， 一段出口压力为 7.8bar, 温度升至 213 °C , 喷入由水分离塔 5侧线采出的稀氨碳水溶液后温度降至 140°C。 然后再送入压缩机二段 2继续压缩， 将气体压缩至 15bar、 223 °C。
b.将压缩后的气体送入二氧化碳分离塔 3底部， 二氧化碳分离塔 3的上、 中、 下部分 别送入来自水分离塔 5塔底的水、 来自水分离塔 5侧线采出的稀氨碳水溶液和来自氨分离 塔 16底部的浓氨碳水溶液的混合液。 二氧化碳分离塔 3底部附有再沸器 4， 防腐空气经再 沸器 4进入二氧化碳分离塔 3。 二氧化碳分离塔 3的操作压力为 15bar, 塔顶温度 70 80 °C , 塔釜温度 155~161 °C。 氨含量 50ppm 的二氧化碳气体从二氧化碳分离塔 3 塔顶排 出； 含少量二氧化碳的氨碳水溶液从塔底排出。
c 从二氧化碳分离塔 3塔底排出的含少量二氧化碳的氨碳水溶液经换热器 8和换热器 7后送入水分离塔 5。 水分离塔 5底部附有再沸器 9, 防腐空气经再沸器 9进入水分离塔 5; 水分离塔 5的顶部设置有回流冷凝器 11 , 所述回流冷凝器 11为空冷器； 水分离塔 5的中 部设置有侧线采出泵 6。 水分离塔 5的操作压力约为 2bar， 回流冷凝器 11出口温度 68~74 °C , 塔釜温度 117~121 °C。 水分离塔 5侧线采出的稀氨碳水溶液分别送往二氧化碳分离塔 3 和尾气压缩机一段 1出口管； 底部采出的水经升压泵 17升压、 换热器 10和冷却器 12冷却 后分别送往二氧化碳分离塔 3顶部和惰洗塔 23顶部， 所述冷却器 12为空冷器， 氨、 二氧 化碳和水的混合气体从水分离塔 5的顶部蒸出。
d. 水分离塔 5顶部蒸出的氨、 二氧化碳和水的混合气体送往氨分离塔 16底部。 从氨 分离塔 16顶部送入循环的氨水， 氨分离塔 16顶部附有回流冷凝器 26, 中部附有循环泵 14 和循环冷却器 13 , 所述循环冷却器 13为空冷器。 氨分离塔 16的操作压力为 2bar, 回流冷 凝器 26出口温度 48~53 °C , 塔釜温度 60~71 °C。 氨分离塔 16底部采出的浓氨碳水溶液经 升压泵 15、 换热器 10、 换热器 7后送入二氧化碳分离塔 3， 从所述氨分离塔 16的顶部分 离出氨气。
实施例 3
本实施例中所述的氨和二氧化碳混合气体的分离方法的工艺流程如图 2所示， 所述的 分离方法为：
a.将压力为 4bar 的三聚氰胺尾气送入尾气压缩机一段 1 进行压缩， 一段出口压力为 lO. lbar, 温度升至 257°C , 喷入由水分离塔 5侧线采出的稀氨碳水溶液后温度降至 140°C。 然后再送入压缩机二段 2继续压缩， 将气体压缩至 25bar、 258 °C。
b.将压缩后的气体送入二氧化碳分离塔 3底部， 二氧化碳分离塔 3的上、 中、 下部分 别送入来自水分离塔 5塔底的水、 来自水分离塔 5侧线采出的稀氨碳水溶液和来自氨分离 塔 16底部的浓氨碳水溶液的混合液。 二氧化碳分离塔 3底部附有再沸器 4， 防腐空气经再 沸器 4进入二氧化碳分离塔 3。 二氧化碳分离塔 3的操作压力为 25bar, 塔顶温度 80 90 °C , 塔釜温度 180~186°C。 氨含量 50ppm 的二氧化碳气体从二氧化碳分离塔 3 塔顶排 出； 含少量二氧化碳的氨碳水溶液从塔底排出。
c 从二氧化碳分离塔 3塔底排出的含少量二氧化碳的氨碳水溶液经换热器 8和换热器 7后送入水分离塔 5。 水分离塔 5底部附有再沸器 9, 防腐空气经再沸器 9进入水分离塔 5。 水分离塔 5的顶部设置有回流冷凝器 11 , 所述回流冷凝器 11为空冷器， 水分离塔 5的中 部设置有侧线采出泵 6。 水分离塔 5的操作压力约为 2bar， 回流冷凝器 11出口温度 68~74 °C , 塔釜温度 117~121 °C。 水分离塔 5侧线采出的稀氨碳水溶液分别送往二氧化碳分离塔 3 和尾气压缩机一段 1出口管； 底部采出的水经升压泵 17升压、 换热器 10和冷却器 12冷却 后分别送往二氧化碳分离塔 3顶部和惰洗塔 23顶部， 所述冷却器 12为空冷器， 氨、 二氧 化碳和水的混合气体从水分离塔 5的顶部蒸出。
d. 水分离塔 5顶部蒸出的氨、 二氧化碳和水的混合气体送往氨分离塔 16底部。 从氨 分离塔 16顶部送入循环的氨水， 氨分离塔 16顶部附有回流冷凝器 26, 中部附有循环泵 14 和循环冷却器 13 , 所述循环冷却器 13为空冷器。 氨分离塔 16的操作压力为 2bar, 回流冷 凝器 26出口温度 48~53 °C , 塔釜温度 60~71 °C。 氨分离塔 16底部采出的浓氨碳水溶液经 升压泵 15、 换热器 10、 换热器 7后送入二氧化碳分离塔 3， 从所述氨分离塔 16的顶部分 离出氨气。
实施例 4
本实施例中所述的氨和二氧化碳混合气体的分离方法的工艺流程如图 2 所示， 所 述的分离方法为：
a. 将压力为 4bar的三聚氰胺尾气送入尾气压缩机一段 1进行压缩， 一段出口压力为 8.6bar, 温度升至 234°C , 喷入由水分离塔 5侧线采出的稀氨碳水溶液后温度降至 140°C。 然后再送入压缩机二段 2继续压缩， 将气体压缩至 18bar、 234°C。
b.将压缩后的气体送入二氧化碳分离塔 3底部， 二氧化碳分离塔 3的上、 中、 下部分 别送入来自水分离塔 5塔底的水、 来自水分离塔 5侧线采出的稀氨碳水溶液和来自氨分离 塔 16底部的浓氨碳水溶液的混合液。 二氧化碳分离塔 3底部附有再沸器 4， 防腐空气经再 沸器 4 进入二氧化碳分离塔 3。 二氧化碳分离塔 3的操作压力为 18bar, 塔顶温度 70 90 °C , 塔釜温度 165~170°C。 氨含量 50ppm 的二氧化碳气体从二氧化碳分离塔 3 塔顶排 出； 含少量二氧化碳的氨碳水溶液从塔底排出。
c 从二氧化碳分离塔 3塔底排出的含少量二氧化碳的氨碳水溶液经换热器 8和换热器 7后送入水分离塔 5。 水分离塔 5底部附有再沸器 9, 防腐空气经再沸器 9进入水分离塔 5。 水分离塔 5的顶部设置有回流冷凝器 11 , 所述回流冷凝器 11为空冷器， 水分离塔 5的中 部设置有侧线采出泵 6。 水分离塔 5的操作压力约为 4bar， 回流冷凝器 11出口温度 85~95 °C , 塔釜温度 138~143.5 °C。 水分离塔 5侧线采出的稀氨碳水溶液分别送往二氧化碳分离 塔 3和尾气压缩机一段 1出口管； 底部采出的水经升压泵 17升压、 换热器 10和冷却器 12 冷却后分别送往碳分离塔顶部和惰洗塔 23顶部， 所述冷却器 12为空冷器， 氨、 二氧化碳 和水的混合气体从水分离塔 5的顶部蒸出。
d. 水分离塔 5顶部蒸出的氨、 二氧化碳和水的混合气体送往氨分离塔 16底部。 从氨 分离塔 16顶部送入循环的氨水， 氨分离塔 16顶部附有回流冷凝器 26, 中部附有循环泵 14 和循环冷却器 13 , 所述循环冷却器 13为空冷器。 氨分离塔 16的操作压力为 4bar, 回流冷 凝器 26出口温度 55~62°C , 塔釜温度 75~85 °C。 氨分离塔 16底部采出的浓氨碳水溶液经 升压泵 15、 换热器 10、 换热器 7后送入二氧化碳分离塔 3， 从所述氨分离塔 16的顶部分 离出氨气。
实施例 5 本实施例中所述的氨和二氧化碳混合气体的分离方法的工艺流程如图 3所示， 碳分离 塔、 水分离塔、 氨分离塔的操作压力均为 18bar, 氨分离塔分出的氨气用以水为冷却介质 的氨气冷凝器冷凝成液氨。 方法如下：
a. 将压力为 4bar的三聚氰胺尾气送入尾气压缩机一段 1进行压缩， 一段出口压力为 8.6bar, 温度升至 234°C , 喷入由水分离塔 5侧线采出的稀氨碳水溶液后温度降至 140°C。 然后再送入压缩机二段 2继续压缩， 将气体压缩至 18bar、 234°C。
b.将压缩后的气体送入二氧化碳分离塔 3底部， 二氧化碳分离塔 3的上、 中、 下部分 别送入来自水分离塔 5塔底的水、 来自水分离塔 5侧线采出的稀氨碳水溶液和来自氨分离 塔 16底部的浓氨碳水溶液的混合液。 二氧化碳分离塔 3底部附有再沸器 4， 防腐空气经再 沸器 4 进入二氧化碳分离塔 3。 二氧化碳分离塔 3的操作压力为 18bar, 塔顶温度 70 90 °C , 塔釜温度 165~170°C。 氨含量 50ppm 的二氧化碳气体从二氧化碳分离塔 3 塔顶排 出； 含少量二氧化碳的氨碳水溶液从塔底排出。
c 从二氧化碳分离塔 3塔底排出的含少量二氧化碳的氨碳水溶液由泵 27泵出， 经换 热器 8和换热器 7后送入水分离塔 5。 水分离塔 5底部附有再沸器 9, 防腐空气经再沸器 9 进入水分离塔 5。 水分离塔 5的顶部设置有回流冷凝器 11 , 所述回流冷凝器 11为空冷器， 水分离塔 5的中部设置有侧线采出泵 6。 水分离塔 5的操作压力约为 18bar， 回流冷凝器 11 出口温度 137 142 °C , 塔釜温度 200 206 °C。 水分离塔 5侧线采出的稀氨碳水溶液分别送 往二氧化碳分离塔 3和尾气压缩机一段 1出口管； 底部采出的水经泵 17、 换热器 7和冷却 器 12冷却后分别送往碳分离塔 3顶部和惰洗塔 23顶部， 所述冷却器 12为空冷器， 氨、 二 氧化碳和水的混合气体从水分离塔 5的顶部蒸出。
d. 水分离塔 5顶部蒸出的氨、 二氧化碳和水的混合气体送往氨分离塔 16底部。 从氨 分离塔 16顶部送入循环的氨水， 氨分离塔 16顶部附有回流冷凝器 26, 中部附有循环泵 14 和循环冷却器 13 , 所述循环冷却器 13为空冷器。 氨分离塔 16的操作压力为 18bar, 回流 冷凝器 26出口温度 42~45 °C , 塔釜温度 97 140 °C。 氨分离塔 16底部采出的浓氨碳水溶液 经泵 15送入二氧化碳分离塔 3， 从所述氨分离塔 16的顶部分离出氨气。
e. 氨分离塔 16的顶部分离出的氨气进入氨气冷凝器 22， 氨气被冷凝成液氨， 未被冷 凝的惰性气体送往惰洗塔 23。 惰洗塔 23附有循环泵 25和循环冷却器 24, 补充水和循环的 水送入惰洗塔 23 的顶部。 洗漆后的氨含量 30ppm的惰性气体由塔顶排入大气， 塔底的 氨水送往氨分离塔 16。
氨气的压缩
将实施例 1-4中氨分离塔 16顶部分离出的氨气送往螺杆压缩机一段 18进行压缩， 压 缩后的氨气进入分凝器 19 冷至 44~46°C , 冷凝下来的液体一部分送往并喷入一段的入口 管， 余下的液体送往氨分离塔 16。 分凝器 19出来的气体进入螺杆压缩机二段继续压缩至 18bar后进入分凝器 21冷至 45~47°C , 冷凝下来的液体一部分送往并喷入螺杆压缩机二段 20的入口管， 余下的液体送往氨分离塔 16。 由分凝器 21出来的气体进入氨气冷凝器 22, 氨气被冷凝成液氨， 未被冷凝的惰性气体送往惰洗塔 23。 惰洗塔 23附有循环泵 25和循环 冷却器 24， 补充水和循环的水送入惰洗塔 23的顶部。 洗漆后的氨含量 30ppm的惰性气 体由塔顶排入大气， 塔底的氨水送往氨分离塔。
上述实施例中均采用了两段压缩的方式对三聚氛胺尾气进行压缩， 作为可选择的实施 方式， 也可以采用单段或者两段以上的方式进行压缩。
还需要说明的是本发明中所述的分离方法不仅适用于三聚氛胺尾气， 也适用于氨气和 二氧化碳质量比为 0.5-1.5之间任一比值且水含量 15%的氨、 二氧化碳和水的混合气体的 分离。 比较例
比较例中采用的分离方法为传统的氨碳混合气体的分离方法， 其流程如图 4所示：
( 1 )将压力为 4bar的三聚氰胺尾气混合气体先送入尾气吸收塔用循环的水吸收， 生 成氨碳水溶液； 未被吸收的惰性气体放空。
( 2 )将所述氨碳水溶液送入二氧化碳分离塔， 二氧化碳分离塔的操作压力为 18bar, 塔顶温度 70~90°C , 塔釜温度 165~170°C。 二氧化碳气体从碳分离塔塔顶分出； 含少量二 氧化碳的氨碳水溶液从碳分离塔塔底采出。
( 3 )将分离出二氧化碳后的溶液送入水分离塔进行解吸， 所述水分离塔的操作压力约 为 2bar, 塔顶温度 68~74°C , 塔釜温度 117~121 °C。 所述氨碳水溶液中的大部分氨、 二氧 化碳和一部分水被蒸出， 剩余的几乎不含氨和二氧化碳的水溶液从所述水分离塔的塔底分 离出来， 所述水分离塔塔底的水溶液经升压泵升压后，一部分送入二氧化碳分离塔， 一部 分送往尾气吸收塔， 另一部分送往氨分离塔。
( 4 ) 将步骤（3 )中蒸出的氨、 二氧化碳和水的混合气体送入氨分离塔塔底， 塔顶加 入循环的氨水。 氨塔的操作压力为 2bar, 塔顶温度 48~53 °C , 塔釜温度 66~71 °C , 从所述 氨分离塔的塔顶分离出氨气， 从所述氨分离塔的塔底得到的含氨气、 二氧化碳的水溶液经 升压泵升压后返回二氧化碳分离塔用作循环水溶液。
利用实施例中的氨气压缩工艺对对比例中的氨气进行压缩、 冷凝， 得到液氨。
实施例与比较例的节能效果测试
为了证明本发明所述技术方案的节能效果， 现将实施例和比较例中每回收一吨液氨消 耗的蒸汽量、 电量和冷却水量进行了测定， 列于下表：
表 1 : 每回收 1吨液氨的能耗
Figure imgf000010_0001
采用比较例中的方法， 每回收一吨液氨需要消耗 6.5吨蒸汽， 明显大于本发明中所述 的氨碳分离方法所消耗的蒸汽量。
显然， 上述实施例仅仅是为清楚地说明所作的举例， 而并非对实施方式的限定。 对于 所属领域的普通技术人员来说， 在上述说明的基础上还可以做出其它不同形式的变化或变 动。 这里无需也无法对所有的实施方式予以穷举， 而由此所引伸出的显而易见的变化或变 动仍处于本发明创造的保护范围之中。

Claims

权 利 要 求 书
1. 一种氨和二氧化碳混合气体的分离方法， 包括：
a. 对氨和二氧化碳混合气体进行压缩， 使压力升至 15-25bar;
b. 将压缩后的气体送入二氧化碳分离塔， 向所述二氧化碳分离塔送入循环水溶液， 从所述二氧化碳分离塔的塔顶分离出二氧化碳气体， 从所述二氧化碳分离塔的塔底得到含 少量二氧化碳的氨碳水溶液；
c 将步骤 b中的氨碳水溶液送入水分离塔进行解吸， 所述氨碳水溶液中的大部分氨、 二氧化碳和一部分水被蒸出， 剩余的几乎不含氨和二氧化碳的水溶液从所述水分离塔的塔 底分离出来；
d. 将步骤 c中蒸出的氨、 二氧化碳和水送入氨分离塔， 从所述氨分离塔的塔顶分离出 氨气。
2. 根据权利要求 1所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 所述步骤 a 中， 对氨和二氧化碳混合气体进行分段压缩， 并在段间向所述混合气体中喷冷却液对所 述混合气体进行冷却。
3. 根据权利要求 1或 2所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 从所 述水分离塔的侧线分离出稀氨碳水溶液， 所述稀氨碳水溶液用作二氧化碳分离塔中的循环 水溶液。
4.根据权利要求 1-3 任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 所 述冷却液为从所述水分离塔的侧线分离出的稀氨碳水溶液或者从所述水分离塔的塔底分离 出的几乎不含氨和二氧化碳的水溶液或者从所述氨分离塔的塔底分离出的含氨、 二氧化碳 的水溶液。
5. 根据权利要求 1-4任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 所 述二氧化碳分离塔的操作压力为 15-25bar, 塔釜操作温度为 155-186°C
6. 根据权利要求 1-5任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 所 述二氧化碳分离塔的操作压力为 18bar, 塔釜操作温度为 165-171 °C
7. 根据权利要求 1-6任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 所 述氨分离塔的操作压力为 2-18bar, 塔釜操作温度为 60-140°C
8. 根据权利要求 7所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 所述氨分 离塔的操作压力为 2-4bar, 塔釜操作温度为 60-85 °C
9. 根据权利要求 1-8任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 所 述水分离塔的顶部设置有回流冷凝器， 所述回流冷凝器为空冷器。
10. 根据权利要求 1-9任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 所述氨分离塔的下部和 /或中部设置有循环泵和循环冷却器。
11. 根据权利要求 10所述的氨和二氧化碳混合气体的分离方法， 其特征在于，所述氨 分离塔的循环冷却器是空冷器。
12. 根据权利要求 1-11 任一所述的氨和二氧化碳混合气体的分离方法， 其特征在 于， 从所述氨分离塔的塔底得到的含氨、 二氧化碳的水溶液返回所述二氧化碳分离塔用 作循环水溶液。
13.根据权利要求 1-12任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 从所述水分离塔的侧线分离出的稀氨碳水溶液从所述二氧化碳分离塔的中部和 /或下部送 入。
14. 根据权利要求 1-13任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 从所述水分离塔的塔底分离出来的水溶液从所述二氧化碳分离塔的顶部送入。
15. 根据权利要求 1-14任一所述的氨和二氧化碳混合气体的分离方法， 其特征在于， 从所述水分离塔的塔底分离出来的水溶液经冷却后再从所述二氧化碳分离塔的顶部送入。
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