CN115121083B - Device and method for purifying and separating ammonia-containing tail gas in carbonylation intermediate production process - Google Patents

Device and method for purifying and separating ammonia-containing tail gas in carbonylation intermediate production process Download PDF

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Publication number
CN115121083B
CN115121083B CN202210824763.2A CN202210824763A CN115121083B CN 115121083 B CN115121083 B CN 115121083B CN 202210824763 A CN202210824763 A CN 202210824763A CN 115121083 B CN115121083 B CN 115121083B
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ammonia
gas
liquid
ammonium bicarbonate
separation
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CN115121083A (en
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李会泉
宋双田
王利国
米谦
郑征
贾中宝
陈家强
胡东平
贺鹏
薛尚龙
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Institute of Process Engineering of CAS
Shaanxi Coal and Chemical Technology Institute Co Ltd
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Institute of Process Engineering of CAS
Shaanxi Coal and Chemical Technology Institute Co Ltd
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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0033—Other features
    • B01D5/0036—Multiple-effect condensation; Fractional condensation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0033—Other features
    • B01D5/0054—General arrangements, e.g. flow sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0078—Condensation of vapours; Recovering volatile solvents by condensation characterised by auxiliary systems or arrangements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0078—Condensation of vapours; Recovering volatile solvents by condensation characterised by auxiliary systems or arrangements
    • B01D5/009—Collecting, removing and/or treatment of the condensate
    • 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

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention provides a device and a method for purifying and separating ammonia-containing tail gas in the production process of a carbonylation intermediate, wherein the device sequentially comprises a gas-liquid separation unit, an ammonium bicarbonate capturing unit, a compression separation unit and an ammonia separation unit, the gas-liquid separation unit comprises a condenser and a first gas-liquid separator, the ammonium bicarbonate capturing unit comprises an ammonium bicarbonate capturing device, the compression separation unit comprises a compressor and a second gas-liquid separator, the ammonia separation unit comprises an ammonia separation tower and a third gas-liquid separator, and liquid phase outlets of the first, second and third gas-liquid separators are connected to the same pipeline for recycling. According to the invention, through the arrangement of the ammonium bicarbonate trapping unit and the multi-stage separation unit, most of organic components are separated through the gas-liquid separation unit, ammonium bicarbonate is separated out through the ammonium bicarbonate trapping unit, and organic matters are separated through the modes of compression separation and tower separation, so that the purification of ammonia-containing tail gas and the efficient recovery of ammonia, ammonium bicarbonate and organic components are realized, meanwhile, the problem that a pipeline is easy to block can be effectively solved, and the continuous and stable operation can be realized for a long time.

Description

Device and method for purifying and separating ammonia-containing tail gas in carbonylation intermediate production process
Technical Field
The invention belongs to the technical field of organic synthesis and separation, and relates to a device and a method for purifying and separating ammonia-containing tail gas in the production process of a carbonylation intermediate.
Background
Urea is a common product in chemical industry, and can be used for preparing important chemicals such as carbamate, carbonic ester, diphenyl urea and the like, and because the urea structure contains carbonyl, the urea structure is generally used for carbonylation synthesis reaction, small molecular ammonia gas is often released in the reaction process, and the generated ammonia-containing tail gas needs to be separated and recovered, but because the urea has the characteristics of easy moisture absorption, poor thermal stability and the like, the ammonia gas is also clamped with ammonium bicarbonate, and the ammonium bicarbonate can be crystallized when meeting cold, so that a tail gas pipeline is easy to block, and the continuous production of a device is influenced.
At present, the industrial treatment and recovery method for ammonia-containing tail gas mainly comprises a water absorption method and a compression separation method, and ammonia water and liquid ammonia are respectively obtained, wherein the water absorption method generally adopts a mode of spraying water after tail gas is heated, so that the problem that ammonium bicarbonate blocks a pipeline in a spraying process, but the water consumption in the process is large, and when an ammonia-containing gas phase contains an organic solvent, the problems of unqualified ammonia water or unqualified tail gas emission pollutants and the like can be caused; the compression separation method is usually to liquefy ammonia gas to form liquid ammonia, but the method has lower requirement on the inlet temperature of a compressor, is easy to cause the problem that ammonium bicarbonate blocks a pipeline, and has higher energy consumption.
For the application of urea in organic synthesis, such as non-phosgene method for producing isocyanate, specifically, the steps of urea carbonylation, alcoholysis, condensation, pyrolysis and the like are adopted, wherein N, N-diphenyl urea (DPU) is an important intermediate in the method and is a product after urea carbonylation, a large amount of ammonia gas is generated in the process, and the ammonia gas is entrained with solvent and ammonium carbonate, so that the effective components in the ammonia-containing tail gas are separated and recovered, and the stable production of the product is greatly influenced.
CN 102001970a discloses a method for preparing diphenyl urea by directly reacting urea and aniline with nitrogen gas and stripping, the method comprises the steps of adding urea and aniline into a reaction kettle according to a certain molar ratio, stirring, introducing nitrogen gas to extract ammonia gas as a reaction byproduct, heating to a reaction temperature of 145-180 ℃, reacting at normal pressure, introducing nitrogen for 2-6 h, stopping stirring, naturally cooling and crystallizing after the reaction is finished, and carrying out suction filtration on the reaction crystallized product to obtain a crystalline diphenyl urea product; the method mainly relates to control of the preparation process of diphenyl urea, and the subsequent treatment and recovery of ammonia-containing gas are not explicitly mentioned.
CN 110817900a discloses a separation device and method of ammonia gas containing carbon dioxide and organic matters, the device comprises a first-stage washing tower, a first-stage washing tower cooler, a second-stage washing tower cooler, a compressor, a gas-liquid separation tank, an ammonia refining tower and a tower top condenser thereof, a reflux tank and a reboiler, a heat exchanger, an organic matter separation tower and a tower top condenser thereof, a reflux tank and a reboiler, a carbonization kettle and a filter; namely, liquid ammonia products and ammonium carbonate products are obtained through the steps of primary washing, secondary washing, pressurizing, ammonia refining, organic matter separation, carbonization and filtration; the device has a complex structure, various operation steps, no clear treatment of ammonium bicarbonate possibly generated in the compression process, and the operation process is greatly influenced by organic components.
In summary, in the process of producing the carbonylation intermediate by the non-phosgene method, for the treatment of the ammonia-containing tail gas, proper equipment and operation are required to be selected according to the composition of the tail gas, so that the efficient recovery of ammonia and organic components can be realized, and the problem of pipeline blockage can be avoided.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention aims to provide a device and a method for purifying and separating ammonia-containing tail gas in the production process of a carbonylation intermediate, the device is used for condensing and separating most of organic components from ammonia-containing organic tail gas through the arrangement of an ammonium bicarbonate capturing unit and a multi-stage separating unit, separating out ammonium bicarbonate, and removing the residual organic components through the modes of compression separation and tower separation, so that the separation and recovery of ammonia, organic components and ammonium bicarbonate in the synthesis tail gas of the carbonylation intermediate are realized, and meanwhile, the problem that a pipeline is easy to block can be effectively solved.
To achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the invention provides an ammonia-containing tail gas purifying and separating device in a carbonylation intermediate production process, which sequentially comprises a gas-liquid separation unit, an ammonium bicarbonate capturing unit, a compression separation unit and an ammonia separation unit, wherein the gas-liquid separation unit comprises a condenser and a first gas-liquid separator, the ammonium bicarbonate capturing unit comprises an ammonium bicarbonate capturing unit, the compression separation unit comprises a compressor and a second gas-liquid separator, the ammonia separation unit comprises an ammonia separation tower and a third gas-liquid separator, and liquid phase outlets of the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator are connected to the same pipeline for recycling.
In the invention, for the production process of the carbonylation intermediate, especially for producing the intermediate of isocyanate, such as diphenyl urea, generally, nitrogen-containing organic raw materials are used, ammonia-containing tail gas is generated after the carbonylation reaction, and then the tail gas also contains ammonium carbonate and organic components based on the characteristics of the raw materials, so the device is provided with an ammonium carbonate trapping unit and a multi-stage separation unit, wherein the ammonium carbonate trapping unit is arranged between the multi-stage separation units, namely, most of the organic components are condensed and separated through a gas-liquid separation unit, ammonium carbonate is separated out through the structural design of an ammonium carbonate trap, and the rest of ammonia-containing gas is further separated out through a compression separation and tower separation mode, so that the effective purification of the synthesis tail gas of the carbonylation intermediate and the efficient recovery of ammonia, ammonium carbonate and organic components are realized, and meanwhile, the problem that the ammonium carbonate is easy to cause pipeline blockage is solved; the device has the advantages of simple structure, continuous and stable operation for a long time, lower cost and high production efficiency.
The following technical scheme is a preferred technical scheme of the invention, but is not a limitation of the technical scheme provided by the invention, and the technical purpose and beneficial effects of the invention can be better achieved and realized through the following technical scheme.
As a preferred technical scheme of the invention, the ammonia-containing tail gas is from a carbonylation intermediate synthesis unit, preferably an N, N-diphenyl urea synthesis unit.
Preferably, the condenser comprises a first condenser and a second condenser, the gas phase outlet of the first condenser being connected to the second condenser and the liquid phase outlet of the first condenser being connected to the carbonylation intermediate synthesis unit.
Preferably, the first condenser is a vertical condenser, the second condenser is a horizontal condenser, and the two condensers are shell-and-tube heat exchangers and are arranged on the ammonia-containing gas tube side.
In the invention, the first condenser and the second condenser are used for cooling ammonia-containing gas with different temperature sections, so that different heat exchange media can be selected, for example, the first condenser selects heat conduction oil, and the second condenser selects circulating water.
Preferably, the first gas-liquid separator is a vertical tank, the top outlet of the first gas-liquid separator is connected with the inlet of the ammonium bicarbonate catcher, and the bottom liquid phase outlet of the first gas-liquid separator is connected with the carbonylation intermediate synthesis unit.
In the invention, the top gas phase pipeline of the first gas-liquid separator can be provided with heat tracing, for example, low-pressure steam is selected so as to avoid ammonium bicarbonate from precipitating in the pipeline in advance due to temperature reduction.
As the preferable technical scheme of the invention, the ammonium bicarbonate catcher is a vertical heat exchanger, a U-shaped pipe is arranged in the vertical heat exchanger to serve as a pipe pass, a heat exchange medium passes through the pipe pass, and an inlet and an outlet of the heat exchange medium are all arranged at the top of the ammonium bicarbonate catcher.
Preferably, a partition plate is arranged in the middle of the ammonium bicarbonate catcher along the longitudinal direction, and the partition plate extends to the bottom of the U-shaped pipe.
Preferably, the side surfaces of the ammonium bicarbonate traps at two sides of the partition plate are respectively provided with an ammonia-containing gas inlet and an ammonia-containing gas outlet.
Preferably, a baffle plate is arranged in the shell layer of the ammonium bicarbonate catcher, and the baffle plate is horizontally arranged or inclined downwards.
In the invention, a horizontal or slightly inclined lower baffle plate is arranged in the shell layer of the ammonium bicarbonate catcher, which is favorable for fully contacting and exchanging heat between ammonia-containing gas and the U-shaped pipe and disturbing crystallization.
Preferably, an interlayer is arranged at the bottom of the tube plate of the upper end enclosure of the ammonium bicarbonate catcher, a spraying heat medium inlet is arranged on the side face of the interlayer, and a spraying port is arranged at the bottom of the interlayer.
In the invention, the bottom of the ammonium bicarbonate catcher is provided with a discharge port for discharging the cleaning liquid after spray flushing, and the side surface of the lower part of the ammonium bicarbonate catcher is also provided with a liquid level port for controlling the liquid level of the cleaning liquid.
Preferably, the number of the ammonium bicarbonate traps is at least one, for example, one, two, three or four, and when the ammonium bicarbonate traps comprise more than two ammonium bicarbonate traps, the ammonium bicarbonate traps are arranged in parallel and alternately operate.
In the invention, the ammonium bicarbonate catcher is used for catching ammonium bicarbonate when in operation, the cutting device is used for cleaning ammonium bicarbonate after the operation is finished, a heating medium for cleaning ammonium bicarbonate can be steam or hot water and is uniformly sprayed on the U-shaped heat exchange tube, and a residual liquid cleaning outlet area is used for sewage treatment and ammonium bicarbonate recovery.
As a preferred embodiment of the present invention, the compressor includes a screw compressor.
Preferably, the compression separation unit further comprises a cooler disposed between the compressor and the second gas-liquid separator.
Preferably, the cooler and the second gas-liquid separator are vertical tanks, and the compressed ammonia-containing gas passes through the shell pass of the cooler.
Preferably, the liquid phase outlet of the second gas-liquid separator is connected to a carbonylation intermediate synthesis unit.
As a preferred technical scheme of the invention, the ammonia separation tower comprises a packed tower, and the packing comprises pall rings and/or silk screen corrugated packing.
Preferably, the top outlet of the ammonia separation tower is also connected with a tower top condenser, the bottom outlet is also connected with a tower kettle reboiler, and the top outlet and the bottom outlet are both vertical heat exchangers.
Preferably, the overhead condenser yields a liquid ammonia product that enters a liquid ammonia storage tank.
Preferably, the third gas-liquid separator is a vertical tank, the top outlet of the third gas-liquid separator is connected with the lower inlet of the ammonia separation tower, and the bottom liquid phase outlet of the third gas-liquid separator is connected with the carbonylation intermediate synthesis unit.
Preferably, a circulating pump is arranged on a converging pipeline of the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator, which is connected to the carbonylation intermediate synthesis unit.
In another aspect, the invention provides a method for purifying and separating ammonia-containing tail gas in the process of producing an intermediate by carbonylation by adopting the device, which comprises the following steps:
(1) Condensing the ammonia-containing tail gas and then performing gas-liquid separation to obtain primary separated ammonia-containing tail gas and liquid-phase organic matters;
(2) Carrying out ammonium bicarbonate trapping on the primary separated ammonia-containing tail gas obtained in the step (1) to obtain secondary separated ammonia-containing tail gas and an ammonium bicarbonate product, wherein the ammonium bicarbonate product is removed through hot spraying;
(3) Compressing and gas-liquid separating the secondary separated ammonia-containing tail gas obtained in the step (2) to obtain tertiary separated ammonia-containing tail gas and liquid-phase organic matters;
(4) And (3) carrying out filler separation and gas-liquid separation on the tertiary separated ammonia-containing tail gas obtained in the step (3) to obtain purified gas and liquid-phase organic matters, and cooling the purified gas to obtain a liquid ammonia product.
As a preferred technical scheme of the invention, the source of the ammonia-containing tail gas in the step (1) comprises a carbonylation intermediate production process, preferably a process for producing N, N-diphenyl urea by taking urea and aniline as raw materials.
Preferably, the ammonia-containing tail gas of step (1) comprises ammonia, ammonium bicarbonate, aniline, carbon dioxide and N-methylaniline.
Preferably, the temperature of the ammonia-containing tail gas in step (1) is 200 to 240 ℃, for example 200 ℃, 205 ℃, 210 ℃, 215 ℃, 220 ℃, 225 ℃, 230 ℃, 235 ℃, 240 ℃ or the like, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the condensing of step (1) comprises a primary condensing and a secondary condensing.
Preferably, the temperature of the ammonia-containing tail gas after the primary condensation is reduced to 100-140 ℃, such as 100 ℃, 110 ℃, 120 ℃, 130 ℃ or 140 ℃, and the like, and the condensed liquid-phase organic matters are returned to the production process of the carbonylation intermediate.
Preferably, the temperature of the ammonia-containing tail gas after secondary condensation is reduced to 60-80 ℃, such as 60 ℃, 65 ℃, 70 ℃, 75 ℃ or 80 ℃, and the like, liquid-phase organic matters are continuously condensed, and the liquid-phase organic matters are returned to the production process of the carbonylation intermediate after gas-liquid separation.
Preferably, after the condensation and gas-liquid separation in step (1), the liquid phase organic matter separated is 90 to 95%, for example 90%, 91%, 92%, 93%, 94% or 95% of the total liquid phase organic matter, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In the invention, the condensation process comprises primary condensation and secondary condensation, wherein liquid-phase organic matters obtained through the primary condensation account for 80-90%, such as 80%, 82%, 85%, 88% or 90% of the total amount of the liquid-phase organic matters, and part of the liquid-phase organic matters separated after the secondary condensation and gas-liquid separation are liquefied again, and the liquid-phase organic matters obtained through the secondary condensation account for 90-95% of the total amount of the organic matters.
As a preferred technical scheme of the invention, the ammonium bicarbonate capturing in the step (2) is performed in an ammonium bicarbonate capturing device.
Preferably, when the ammonium bicarbonate is trapped, the ammonia-containing tail gas separated for the first time is continuously cooled to below 40 ℃, such as 40 ℃, 38 ℃, 35 ℃, 32 ℃, 30 ℃ or 25 ℃, and the like, and the ammonium bicarbonate is separated out on a U-shaped pipe in the ammonium bicarbonate trap.
Preferably, when the number of ammonium bicarbonate traps includes more than two, the operation is alternated.
Preferably, the thermal spraying in the step (2) is spraying and flushing by adopting a thermal medium, and the precipitated ammonium bicarbonate is dissolved and removed.
Preferably, the heat medium comprises steam or hot water for a removal time of not more than 0.5h, such as 0.5h, 0.45h, 0.4h, 0.35h, 0.3h, 0.25h or 0.2h, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In the invention, the top of the ammonium bicarbonate catcher is provided with the heat medium spray, the heat medium is hot water or low-pressure steam, such as 80 ℃ hot water or 0.2MPaG steam, the melting point of ammonium bicarbonate is low and the ammonium bicarbonate is easy to dissolve in water, and the ammonium bicarbonate can be rapidly decarbonized in the system cutting stage of equipment, so that the required time is short.
In a preferred embodiment of the present invention, the pressure of the secondary separation ammonia-containing tail gas in the step (3) is 0.05 to 0.2MPaG, for example, 0.05MPaG, 0.08MPaG, 0.1MPaG, 0.12MPaG, 0.15MPaG, 0.18MPaG or 0.2MPaG, etc., but the secondary separation ammonia-containing tail gas is not limited to the above-mentioned values, and other non-mentioned values in the above-mentioned value range are similarly applicable.
Preferably, the temperature of the secondary separation ammonia-containing tail gas after compression is increased, and the gas-liquid separation after cooling is performed again.
Preferably, after the gas-liquid separation in the step (3), the liquid-phase organic matters return to the production process of the carbonylation intermediate.
Preferably, the pressure of the ammonia-containing tail gas after the gas-liquid separation in step (3) is 2.6 to 3.2MPaG, for example, 2.6MPaG, 2.7MPaG, 2.8MPaG, 2.9MPaG, 3.0MPaG, 3.1MPaG or 3.2MPaG, etc., but is not limited to the recited values, and other non-recited values within the range of the values are equally applicable.
As a preferred embodiment of the present invention, the separation of the filler in the step (4) is performed in an ammonia separation column.
Preferably, the packing in the ammonia separation column comprises pall rings and/or wire mesh corrugated packing.
Preferably, the pressure of the separation of the filler in step (4) is 2.6 to 3.2MPaG, such as 2.6MPaG, 2.7MPaG, 2.8MPaG, 2.9MPaG, 3.0MPaG, 3.1MPaG or 3.2MPaG, etc., and the temperature is 60 to 70 ℃, such as 60 ℃, 62 ℃, 64 ℃, 66 ℃, 68 ℃ or 70 ℃, etc., but not limited to the recited values, other non-recited values within the respective numerical ranges are equally applicable.
Preferably, in the step (4), the filler is separated, the ammonia-containing tail gas is partially liquefied in three times, the non-liquefied gas phase leaves from the top of the tower, and the liquefied organic matters are heated by the tower kettle to perform gas-liquid separation again.
Preferably, the purified gas in step (4) is cooled to 40-60 ℃ to obtain a liquid ammonia product, for example, 40 ℃,45 ℃, 50 ℃, 55 ℃, 60 ℃ or the like, but the purified gas is not limited to the recited values, and other non-recited values within the range of the recited values are equally applicable.
Preferably, after the gas-liquid separation in the step (4), the gas phase returns to the ammonia separation tower, and the liquid phase organic matter returns to the production process of the carbonylation intermediate.
Preferably, the liquid phase organic matters separated in step (3) and step (4) are depressurized to 0 to 0.5MPaG, for example, 0MPaG, 0.1MPaG, 0.2MPaG, 0.3MPaG, 0.4MPaG or 0.5MPaG, etc., and then mixed with the liquid phase organic matters separated in step (1) and sent to the carbonylation intermediate synthesis unit.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the device, most organic components are condensed and separated through the gas-liquid separation unit, then the ammonium carbonate is separated out through the structural design of the ammonium carbonate catcher, and the rest ammonia-containing gas is further separated out through the compression separation and tower separation mode, so that the effective purification of the synthesis tail gas of the carbonylation intermediate and the efficient recovery of ammonia, ammonium carbonate and organic components are realized, the removal rate of the ammonium carbonate is more than 99.5%, the recovery rate of the organic components is more than 99.9%, and the purity of a liquid ammonia product is more than 99.9%;
(2) The device can effectively solve the problem that ammonium bicarbonate is easy to cause pipeline blockage, continuous and stable operation can reach more than 3000 hours, equipment cost is low, and production efficiency is high.
Drawings
Fig. 1 is a schematic structural diagram of an apparatus for purifying and separating ammonia-containing tail gas in the process of producing an intermediate for carbonylation according to embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of the structure of the ammonium bicarbonate catcher provided in embodiment 1 of the present invention;
the device comprises a first condenser, a second condenser, a first gas-liquid separator, a 4-ammonium bicarbonate catcher, a 41-U-shaped pipe, a 42-baffle plate, a 43-baffle plate, a 44-interlayer, a 45-spraying port, a 5-compressor, a 6-cooler, a second gas-liquid separator, an 8-ammonia separating tower, a third gas-liquid separator and a 10-carbonylation intermediate synthesis unit.
Detailed Description
For better illustrating the present invention, the technical scheme of the present invention is convenient to understand, and the present invention is further described in detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.
The following are exemplary but non-limiting examples of the invention:
example 1:
the embodiment provides a device for purifying and separating ammonia-containing tail gas in the production process of a carbonylation intermediate, the structure schematic diagram of the device is shown in fig. 1, the device sequentially comprises a gas-liquid separation unit, an ammonium bicarbonate capturing unit, a compression separation unit and an ammonia separation unit, the gas-liquid separation unit comprises a condenser and a first gas-liquid separator 3, the ammonium bicarbonate capturing unit comprises an ammonium bicarbonate capturing unit 4, the compression separation unit comprises a compressor 5 and a second gas-liquid separator 7, the ammonia separation unit comprises an ammonia separation tower 8 and a third gas-liquid separator 9, and liquid phase outlets of the first gas-liquid separator 3, the second gas-liquid separator 7 and the third gas-liquid separator 9 are connected to the same pipeline for recycling.
The ammonia-containing tail gas comes from a carbonylation intermediate synthesis unit 10, in particular an N, N-diphenyl urea synthesis unit.
The condenser comprises a first condenser 1 and a second condenser 2, the gas phase outlet of the first condenser 1 is connected to the second condenser 2, and the liquid phase outlet of the first condenser 1 is connected to the carbonylation intermediate synthesis unit 10.
The first condenser 1 is a vertical condenser, the second condenser 2 is a horizontal condenser, and both the two condensers are shell-and-tube heat exchangers and are arranged on the ammonia-containing gas pipe side.
The first gas-liquid separator 3 is a vertical tank, the top outlet of the first gas-liquid separator 3 is connected with the inlet of the ammonium bicarbonate catcher 4, and the bottom liquid phase outlet of the first gas-liquid separator 3 is connected with the carbonylation intermediate synthesis unit 10.
The schematic structure of the ammonium bicarbonate catcher 4 is shown in fig. 2, the ammonium bicarbonate catcher 4 is a vertical heat exchanger, a U-shaped tube 41 is arranged in the vertical heat exchanger to serve as a tube pass, a heat exchange medium passes through the tube pass, and an inlet and an outlet of the heat exchange medium are arranged at the top of the ammonium bicarbonate catcher 4.
A partition plate 42 is longitudinally arranged in the middle of the ammonium bicarbonate catcher 4, and the partition plate 42 extends to the bottom of the U-shaped pipe 41; the side surfaces of the ammonium bicarbonate catcher 4 on the two sides of the partition plate 42 are respectively provided with an ammonia-containing gas inlet and an ammonia-containing gas outlet.
A baffle plate 43 is arranged in the shell layer of the ammonium bicarbonate catcher 4, and the baffle plate 43 is horizontally arranged.
An interlayer 44 is arranged at the bottom of the upper end socket tube plate of the ammonium bicarbonate catcher 4, a spraying heat medium inlet is arranged on the side surface of the interlayer 44, and a spraying port 45 is arranged at the bottom of the interlayer 44; the thermal medium vapor.
The number of the ammonium bicarbonate traps 4 is two, and the two traps are arranged in parallel and run alternately.
The compressor 4 is a screw compressor.
The compression separation unit further comprises a cooler 6, which cooler 6 is arranged between the compressor 5 and the second gas-liquid separator 7.
The cooler 6 and the second gas-liquid separator 7 are vertical tanks, and the compressed ammonia-containing gas passes through the shell pass of the cooler 6.
The liquid phase outlet of the second gas-liquid separator 7 is connected to a carbonylation intermediate synthesis unit 10.
The ammonia separation column 8 comprises a packed column, the packing comprising pall rings.
The top outlet of the ammonia separation tower 8 is also connected with a tower top condenser, the bottom outlet is also connected with a tower kettle reboiler, and the top outlet and the bottom outlet are both vertical heat exchangers; the tower top condenser obtains a liquid ammonia product, and the liquid ammonia product enters a liquid ammonia storage tank.
The third gas-liquid separator 9 is a vertical tank, the top outlet of the third gas-liquid separator 9 is connected with the lower inlet of the ammonia separation tower 8, and the bottom liquid phase outlet of the third gas-liquid separator 9 is connected with the carbonylation intermediate synthesis unit 10.
The first gas-liquid separator 3, the second gas-liquid separator 7 and the third gas-liquid separator 9 are connected to a converging pipeline of the carbonylation intermediate synthesis unit 10 and are provided with a circulating pump.
Example 2:
the embodiment provides an ammonia-containing tail gas purifying and separating device in a carbonylation intermediate production process, which sequentially comprises a gas-liquid separation unit, an ammonium bicarbonate capturing unit, a compression separation unit and an ammonia separation unit, wherein the gas-liquid separation unit comprises a condenser and a first gas-liquid separator 3, the ammonium bicarbonate capturing unit comprises an ammonium bicarbonate capturing unit 4, the compression separation unit comprises a compressor 5 and a second gas-liquid separator 7, the ammonia separation unit comprises an ammonia separation tower 8 and a third gas-liquid separator 9, and liquid phase outlets of the first gas-liquid separator 3, the second gas-liquid separator 7 and the third gas-liquid separator 9 are connected to the same pipeline for recycling.
The ammonia-containing tail gas comes from a carbonylation intermediate synthesis unit 10, in particular an N, N-diphenyl urea synthesis unit.
The condenser comprises a first condenser 1 and a second condenser 2, the gas phase outlet of the first condenser 1 is connected to the second condenser 2, and the liquid phase outlet of the first condenser 1 is connected to the carbonylation intermediate synthesis unit 10.
The first condenser 1 is a vertical condenser, the second condenser 2 is a horizontal condenser, and both the two condensers are shell-and-tube heat exchangers and are arranged on the ammonia-containing gas pipe side.
The first gas-liquid separator 3 is a vertical tank, the top outlet of the first gas-liquid separator 3 is connected with the inlet of the ammonium bicarbonate catcher 4, and the bottom liquid phase outlet of the first gas-liquid separator 3 is connected with the carbonylation intermediate synthesis unit 10.
The ammonium bicarbonate catcher 4 is a vertical heat exchanger, a U-shaped pipe 41 is arranged in the vertical heat exchanger to serve as a pipe pass, a heat exchange medium passes through the pipe pass, and an inlet and an outlet of the heat exchange medium are arranged at the top of the ammonium bicarbonate catcher 4.
A partition plate 42 is longitudinally arranged in the middle of the ammonium bicarbonate catcher 4, and the partition plate 42 extends to the bottom of the U-shaped pipe 41; the side surfaces of the ammonium bicarbonate catcher 4 on the two sides of the partition plate 42 are respectively provided with an ammonia-containing gas inlet and an ammonia-containing gas outlet.
A baffle plate 43 is arranged in the shell layer of the ammonium bicarbonate catcher 4, and the baffle plate 43 is arranged in a downward inclined mode.
An interlayer 44 is arranged at the bottom of the upper end socket tube plate of the ammonium bicarbonate catcher 4, a spraying heat medium inlet is arranged on the side surface of the interlayer 44, and a spraying port 45 is arranged at the bottom of the interlayer 44; the heat medium is hot water.
The number of the ammonium bicarbonate traps 4 is three, and the ammonium bicarbonate traps are arranged in parallel and run alternately.
The compressor 4 is a centrifugal compressor.
The compression separation unit further comprises a cooler 6, which cooler 6 is arranged between the compressor 5 and the second gas-liquid separator 7.
The cooler 6 and the second gas-liquid separator 7 are vertical tanks, and the compressed ammonia-containing gas passes through the shell pass of the cooler 6.
The liquid phase outlet of the second gas-liquid separator 7 is connected to a carbonylation intermediate synthesis unit 10.
The ammonia separation column 8 comprises a packed column, the packing comprising wire mesh corrugated packing.
The top outlet of the ammonia separation tower 8 is also connected with a tower top condenser, the bottom outlet is also connected with a tower kettle reboiler, and the top outlet and the bottom outlet are both vertical heat exchangers; the tower top condenser obtains a liquid ammonia product, and the liquid ammonia product enters a liquid ammonia storage tank.
The third gas-liquid separator 9 is a vertical tank, the top outlet of the third gas-liquid separator 9 is connected with the lower inlet of the ammonia separation tower 8, and the bottom liquid phase outlet of the third gas-liquid separator 9 is connected with the carbonylation intermediate synthesis unit 10.
Example 3:
the embodiment provides a method for purifying and separating ammonia-containing tail gas in the production process of a carbonylation intermediate, which is carried out by adopting the device in embodiment 1 and comprises the following steps:
(1) Condensing the ammonia-containing tail gas to separate gas from liquid, wherein the ammonia-containing tail gas is fromThe process for producing N, N-diphenyl urea by using urea and aniline as raw materials comprises the following steps of 30wt% of ammonia gas, 67wt% of aniline and 100g/m 3 The temperature of the ammonia-containing tail gas is 235 ℃, the condensation comprises primary condensation and secondary condensation, the temperature of the ammonia-containing tail gas after the primary condensation is reduced to 120 ℃, the temperature of the ammonia-containing tail gas after the secondary condensation is reduced to 60 ℃, and the condensed aniline accounts for 95% of the total aniline through gas-liquid separation and returns to the production process of N, N-diphenyl urea to obtain primary separated ammonia-containing tail gas;
(2) The primary separated ammonia-containing tail gas obtained in the step (1) enters an ammonia carbonate catcher 4 to carry out ammonia carbonate catching, the primary separated ammonia-containing tail gas is continuously cooled to 38 ℃, and ammonia carbonate is separated out on a U-shaped pipe 41 in the ammonia carbonate catcher 4, and secondary separated ammonia-containing tail gas is obtained; the ammonium bicarbonate product is sprayed and washed by steam, and the precipitated ammonium bicarbonate is dissolved and removed for 0.4h;
(3) Compressing the secondary separated ammonia-containing tail gas obtained in the step (2), wherein the pressure before compression is 0.1MPaG, the temperature of the secondary separated ammonia-containing tail gas after compression is increased, cooling is carried out again, and then gas-liquid separation is carried out, so that tertiary separated ammonia-containing tail gas and liquid-phase aniline are obtained, the pressure of the tertiary separated ammonia-containing tail gas is 2.6MPaG, and the aniline is returned to the production process of N, N-diphenyl urea after being decompressed to 0.3 MPaG;
(4) And (3) carrying out filler separation on the tertiary separated ammonia-containing tail gas obtained in the step (3) by adopting an ammonia separation tower 8, wherein filler in the ammonia separation tower 8 is pall ring, the pressure of filler separation is 2.9MPaG, the temperature is 66 ℃, the tertiary separated ammonia-containing tail gas is partially liquefied, the non-liquefied gas phase leaves from the top of the tower, the obtained purified gas is cooled to 40 ℃ to obtain a liquid ammonia product, the liquefied aniline is heated by a tower kettle to carry out gas-liquid separation again, the gas phase returns to the ammonia separation tower 8, and the liquid-phase aniline returns to the production process of N, N-diphenyl urea after being depressurized to 0.3 MPaG.
In the embodiment, the device and the method are adopted to purify and separate the ammonia-containing tail gas, the removal rate of the ammonium carbonate reaches 99.97%, the recovery rate of the aniline reaches 99.92%, the purity of the liquid ammonia product can reach 99.95% according to the content of the ammonium carbonate and the recovery amount of the aniline in the residual tail gas in the step (2), and the continuous and stable operation time of the device reaches 3000 hours.
Example 4:
the embodiment provides a method for purifying and separating ammonia-containing tail gas in the production process of a carbonylation intermediate, which is carried out by adopting the device in embodiment 1 and comprises the following steps:
(1) Condensing ammonia-containing tail gas, and separating gas from liquid, wherein the ammonia-containing tail gas is obtained from the process of producing N, N-diphenyl urea by taking urea and aniline as raw materials, and comprises 35wt% of ammonia gas, 60wt% of aniline and 80g/m 3 The temperature of the ammonia-containing tail gas is 240 ℃, the condensation comprises primary condensation and secondary condensation, the temperature of the ammonia-containing tail gas after the primary condensation is reduced to 140 ℃, the temperature of the ammonia-containing tail gas after the secondary condensation is reduced to 80 ℃, and condensed aniline accounts for 90% of the total aniline through gas-liquid separation and returns to the production process of N, N-diphenyl urea to obtain primary separated ammonia-containing tail gas;
(2) The primary separated ammonia-containing tail gas obtained in the step (1) enters an ammonia carbonate catcher 4 to carry out ammonia carbonate catching, the primary separated ammonia-containing tail gas is continuously cooled to 40 ℃, and ammonia carbonate is separated out on a U-shaped pipe 41 in the ammonia carbonate catcher 4, and secondary separated ammonia-containing tail gas is obtained; the ammonium bicarbonate product is sprayed and washed by steam, and the precipitated ammonium bicarbonate is dissolved and removed for 0.5h;
(3) Compressing the secondary separated ammonia-containing tail gas obtained in the step (2), wherein the pressure before compression is 0.05MPaG, the temperature of the secondary separated ammonia-containing tail gas after compression is increased, cooling is carried out again, and then gas-liquid separation is carried out, so that tertiary separated ammonia-containing tail gas and liquid-phase aniline are obtained, the pressure of the tertiary separated ammonia-containing tail gas is 3.0MPaG, and the aniline returns to the production process of N, N-diphenyl urea after being decompressed to 0.5 MPaG;
(4) And (3) carrying out filler separation on the tertiary separated ammonia-containing tail gas obtained in the step (3) by adopting an ammonia separation tower 8, wherein filler in the ammonia separation tower 8 is pall ring, the pressure of filler separation is 3.0MPaG, the temperature is 70 ℃, the tertiary separated ammonia-containing tail gas is partially liquefied, the non-liquefied gas phase leaves from the top of the tower, the obtained purified gas is cooled to 50 ℃ to obtain a liquid ammonia product, the liquefied aniline is heated by a tower kettle to carry out gas-liquid separation again, the gas phase returns to the ammonia separation tower 8, and the liquid phase aniline returns to the production process of N, N-diphenyl urea after being depressurized to 0.5 MPaG.
In the embodiment, the device and the method are adopted to purify and separate the ammonia-containing tail gas, the removal rate of the ammonium carbonate reaches 99.92%, the recovery rate of the aniline reaches 99.94%, the purity of the liquid ammonia product can reach 99.93% according to the content of the ammonium carbonate and the recovery amount of the aniline in the residual tail gas in the step (2), and the continuous and stable operation time of the device reaches 3100h.
Example 5:
the embodiment provides a method for purifying and separating ammonia-containing tail gas in the production process of a carbonylation intermediate, which is carried out by adopting the device in embodiment 2 and comprises the following steps:
(1) Condensing ammonia-containing tail gas from the process of producing N, N-diphenyl urea with urea and aniline as material, wherein the ammonia-containing tail gas comprises ammonia 40wt%, aniline 57.5wt% and ammonia 90g/m 3 The temperature of the ammonia-containing tail gas is 200 ℃, the condensation comprises primary condensation and secondary condensation, the temperature of the ammonia-containing tail gas after the primary condensation is reduced to 100 ℃, the temperature of the ammonia-containing tail gas after the secondary condensation is reduced to 70 ℃, and condensed aniline accounts for 92% of the total aniline through gas-liquid separation and returns to the production process of N, N-diphenyl urea to obtain primary separated ammonia-containing tail gas;
(2) The primary separated ammonia-containing tail gas obtained in the step (1) enters an ammonia carbonate catcher 4 for ammonia carbonate catching, the primary separated ammonia-containing tail gas is continuously cooled to 35 ℃, and ammonia carbonate is separated out on a U-shaped pipe 41 in the ammonia carbonate catcher 4, and secondary separated ammonia-containing tail gas is obtained; spraying and flushing the ammonium bicarbonate product by adopting hot water at 80 ℃, and dissolving and removing the precipitated ammonium bicarbonate for 0.3h;
(3) Compressing the secondary separated ammonia-containing tail gas obtained in the step (2), wherein the pressure before compression is 0.2MPaG, the temperature of the secondary separated ammonia-containing tail gas after compression is increased, cooling is carried out again, and then gas-liquid separation is carried out, so that tertiary separated ammonia-containing tail gas and liquid-phase aniline are obtained, the pressure of the tertiary separated ammonia-containing tail gas is 3.2MPaG, and the aniline returns to the production process of N, N-diphenyl urea after being decompressed to 0.1 MPaG;
(4) And (3) carrying out filler separation on the tertiary separated ammonia-containing tail gas obtained in the step (3) by adopting an ammonia separation tower 8, wherein the filler in the ammonia separation tower 8 is silk screen corrugated filler, the pressure of filler separation is 3.2MPaG, the temperature is 60 ℃, the tertiary separated ammonia-containing tail gas is partially liquefied, the non-liquefied gas phase leaves from the top of the tower, the obtained purified gas is cooled to 60 ℃ to obtain a liquid ammonia product, the liquefied aniline is heated by a tower kettle to carry out gas-liquid separation again, the gas phase returns to the ammonia separation tower 8, and the liquid phase aniline returns to the production process of N, N-diphenyl urea after being depressurized to 0.1 MPaG.
In the embodiment, the device and the method are adopted to purify and separate the ammonia-containing tail gas, the removal rate of the ammonium carbonate reaches 99.9%, the recovery rate of the aniline reaches 99.91%, the purity of the liquid ammonia product can reach 99.92% according to the content of the ammonium carbonate and the recovery amount of the aniline in the residual tail gas in the step (2), and the continuous and stable operation time of the device reaches 3200h.
Comparative example 1:
this comparative example provides an apparatus and a method for purifying and separating ammonia-containing tail gas in the production process of carbonylation intermediates, the apparatus is different from the apparatus in example 1 only in that: the ammonium bicarbonate trap 4 is replaced with a conventional shell-and-tube heat exchanger.
The method is described with reference to the method in example 3, with the only difference that: and (3) carrying out heat exchange and cooling on the ammonia-containing tail gas subjected to primary separation in the step (2) by adopting a shell-and-tube heat exchanger, and separating out ammonium bicarbonate.
In this comparative example, because no ammonium bicarbonate catcher is provided, ammonium bicarbonate is precipitated in the conventional heat exchanger, and is easy to cause accumulation and blockage inside the heat exchanger, and is difficult to directly rinse, and each time the operation needs to be suspended, the long-time stable operation cannot be performed, and the heat exchange effect is reduced over time, and the full precipitation of ammonium bicarbonate is difficult to realize, so that the subsequent separation process is influenced.
According to the device, through the arrangement of the ammonium bicarbonate capturing unit and the multistage separation unit, most of organic components are condensed and separated through the gas-liquid separation unit, ammonium bicarbonate is separated out through the structural design of the ammonium bicarbonate capturing unit, and the rest ammonia-containing gas is further separated out through the compression separation and tower separation modes, so that the effective purification of the tail gas generated by synthesizing the carbonylation intermediates and the efficient recovery of ammonia, ammonium bicarbonate and organic components are realized, the removal rate of the ammonium bicarbonate is up to more than 99.5%, the recovery rate of the organic components is up to more than 99.9%, and the purity of a liquid ammonia product is up to more than 99.9%; the device can effectively solve the problem that ammonium bicarbonate is easy to cause pipeline blockage, continuous and stable operation can reach more than 3000 hours, equipment cost is lower, and production efficiency is high.
The present invention is described in detail by the above embodiments, but the present invention is not limited to the above detailed devices and methods, i.e., it does not mean that the present invention must be implemented by the above detailed devices and methods. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions for the apparatus of the present invention, addition of auxiliary apparatus, selection of specific modes, etc., are within the scope of the present invention and the scope of the disclosure.

Claims (41)

1. The device for purifying and separating the ammonia-containing tail gas in the production process of the carbonylation intermediate is characterized by sequentially comprising a gas-liquid separation unit, an ammonium bicarbonate capturing unit, a compression separation unit and an ammonia separation unit; the ammonia separation unit comprises an ammonia separation tower and a third gas-liquid separator, and liquid phase outlets of the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator are connected to the same pipeline for recycling;
the ammonium bicarbonate catcher is a vertical heat exchanger, a U-shaped pipe is arranged in the vertical heat exchanger to serve as a tube pass, and a heat exchange medium passes through the tube pass; the middle part of the ammonium bicarbonate catcher is longitudinally provided with a baffle plate, the baffle plate extends to the bottom of the U-shaped pipe, and the side surfaces of the ammonium bicarbonate catcher on two sides of the baffle plate are respectively provided with an ammonia-containing gas inlet and an ammonia-containing gas outlet; a baffle plate is arranged in the shell layer of the ammonium bicarbonate catcher, and the baffle plate is horizontally arranged or is inclined downwards; the bottom of the tube plate of the upper end enclosure of the ammonium bicarbonate catcher is provided with an interlayer, the side surface of the interlayer is provided with a spraying heat medium inlet, and the bottom of the interlayer is provided with a spraying opening.
2. The apparatus according to claim 1, wherein the ammonia-containing tail gas is from a carbonylation intermediate synthesis unit.
3. The apparatus according to claim 2, wherein the ammonia-containing tail gas is from an N, N-diphenyl urea synthesis unit.
4. The apparatus according to claim 2, wherein the condenser comprises a first condenser and a second condenser, the gas phase outlet of the first condenser being connected to the second condenser and the liquid phase outlet of the first condenser being connected to the carbonylation intermediate synthesis unit.
5. The apparatus of claim 4, wherein the first condenser is a vertical condenser and the second condenser is a horizontal condenser, both of which are shell-and-tube heat exchangers, and wherein the ammonia-containing gas passes through a tube pass.
6. The apparatus according to claim 2, wherein the first gas-liquid separator is a vertical tank, a top outlet of the first gas-liquid separator is connected to an inlet of an ammonium bicarbonate trap, and a bottom liquid phase outlet of the first gas-liquid separator is connected to a carbonylation intermediate synthesis unit.
7. The apparatus of claim 1, wherein at least one of the ammonium bicarbonate traps is provided, and when the ammonium bicarbonate traps include two or more ammonium bicarbonate traps, the ammonium bicarbonate traps are arranged in parallel and alternately operate.
8. The apparatus of claim 1, wherein the compressor comprises a screw compressor.
9. The apparatus of claim 1, wherein the compression separation unit further comprises a cooler disposed between the compressor and the second gas-liquid separator.
10. The apparatus of claim 9, wherein the cooler and the second gas-liquid separator are vertical tanks, and the compressed ammonia-containing gas passes through a shell side of the cooler.
11. The apparatus according to claim 2, wherein the liquid phase outlet of the second gas-liquid separator is connected to a carbonylation intermediate synthesis unit.
12. The apparatus of claim 1, wherein the ammonia separation column comprises a packed column, the packing in the packed column comprising pall rings and/or wire mesh corrugated packing.
13. The apparatus of claim 1, wherein the top outlet of the ammonia separation column is further connected with a top condenser and the bottom outlet is further connected with a bottom reboiler, both of which are vertical heat exchangers.
14. The apparatus of claim 13, wherein the overhead condenser receives a liquid ammonia product that enters a liquid ammonia storage tank.
15. The apparatus according to claim 2, wherein the third gas-liquid separator is a vertical tank, a top outlet of the third gas-liquid separator is connected to a lower inlet of the ammonia separation column, and a bottom liquid phase outlet of the third gas-liquid separator is connected to the carbonylation intermediate synthesis unit.
16. The apparatus according to claim 2, wherein a circulation pump is provided on a merging line of the first, second and third gas-liquid separators connected to the carbonylation intermediate synthesis unit.
17. A process for the purification and separation of ammonia-containing tail gas in the production of an intermediate for carbonylation using an apparatus according to any one of claims 1 to 16, comprising the steps of:
(1) Condensing the ammonia-containing tail gas and then performing gas-liquid separation to obtain primary separated ammonia-containing tail gas and liquid-phase organic matters;
(2) Carrying out ammonium bicarbonate trapping on the primary separated ammonia-containing tail gas obtained in the step (1) to obtain secondary separated ammonia-containing tail gas and an ammonium bicarbonate product, wherein the ammonium bicarbonate product is removed through hot spraying;
(3) Compressing and gas-liquid separating the secondary separated ammonia-containing tail gas obtained in the step (2) to obtain tertiary separated ammonia-containing tail gas and liquid-phase organic matters;
(4) And (3) carrying out filler separation and gas-liquid separation on the tertiary separated ammonia-containing tail gas obtained in the step (3) to obtain purified gas and liquid-phase organic matters, and cooling the purified gas to obtain a liquid ammonia product.
18. The process of claim 17, wherein the source of ammonia-containing tail gas of step (1) comprises a carbonylation intermediate production process.
19. The method of claim 18, wherein the source of ammonia-containing tail gas of step (1) is a process for producing N, N-diphenyl urea starting from urea and aniline.
20. The method of claim 17, wherein the ammonia-containing tail gas of step (1) comprises ammonia, ammonium bicarbonate, aniline, carbon dioxide, and N-methylaniline.
21. The method of claim 17, wherein the ammonia-containing tail gas of step (1) has a temperature of 200 to 240 ℃.
22. The method of claim 17, wherein the condensing of step (1) comprises primary condensing and secondary condensing.
23. A process according to claim 22 wherein the temperature of the ammonia-containing tail gas after the primary condensation is reduced to 100 to 140 ℃ and the condensed liquid phase organics are returned to the carbonylation intermediate production.
24. The method according to claim 22, wherein the temperature of the ammonia-containing tail gas after the secondary condensation is reduced to 60-80 ℃, the liquid-phase organic matter continues to condense, and the liquid-phase organic matter returns to the production process of the carbonylation intermediate after gas-liquid separation.
25. The method of claim 17, wherein after the condensing and gas-liquid separation in step (1), the separated liquid phase organic matter accounts for 90-95% of the total amount of the liquid phase organic matter.
26. The method of claim 17, wherein the ammonium bicarbonate capture of step (2) is performed in an ammonium bicarbonate capture.
27. The method of claim 26, wherein the primary separated ammonia-containing tail gas is cooled to below 40 ℃ during the ammonium bicarbonate capture, and the ammonium bicarbonate is precipitated on a U-shaped tube in the ammonium bicarbonate capture.
28. The method of claim 26, wherein the ammonium bicarbonate traps are operated alternately when the number includes more than two.
29. The method of claim 17, wherein the thermal spraying in step (2) is a spray rinsing with a thermal medium to dissolve and remove precipitated ammonium carbonate.
30. The method of claim 29, wherein the thermal medium comprises steam or hot water for a removal time of no more than 0.5 hours.
31. The method of claim 17, wherein the pressure of the secondary separated ammonia-containing tail gas of step (3) is from 0.05 to 0.2MPaG.
32. The method according to claim 17, wherein the temperature of the secondary separation ammonia-containing tail gas after compression is raised and the gas-liquid separation after cooling is performed again.
33. The process of claim 17 wherein after said gas-liquid separation of step (3), liquid phase organics are returned to the process for the carbonylation of intermediates.
34. The method according to claim 17, wherein the pressure of the tertiary separation ammonia-containing tail gas after the gas-liquid separation in step (3) is 2.6 to 3.2MPaG.
35. The method of claim 17, wherein the separation of the packing in step (4) is performed in an ammonia separation column.
36. The method of claim 35, wherein the packing within the ammonia separation column comprises pall rings and/or wire mesh corrugated packing.
37. The process of claim 17, wherein the packing separation in step (4) is carried out at a pressure of 2.6 to 3.2MPaG and a temperature of 60 to 70 ℃.
38. The method according to claim 17, wherein in the step (4), the filler is separated, the ammonia-containing tail gas is partially liquefied in three times, the non-liquefied gas phase leaves from the top of the tower, and the liquefied organic matter is heated by the tower bottom to perform gas-liquid separation again.
39. The method of claim 17, wherein the purified gas of step (4) is cooled to 40-60 ℃ to produce a liquid ammonia product.
40. The process of claim 35 wherein after said gas-liquid separation in step (4), the gas phase is returned to the ammonia separation column and the liquid phase organics are returned to the carbonylation intermediate production process.
41. The process according to claim 17, wherein the liquid phase organics separated in step (3) and step (4) are reduced in pressure to 0 to 0.5mpa g and then mixed with the liquid phase organics separated in step (1) and fed to the carbonylation intermediate synthesis unit.
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