CN115121083A - Device and method for purifying and separating ammonia-containing tail gas in production process of carbonylation intermediate - Google Patents
Device and method for purifying and separating ammonia-containing tail gas in production process of carbonylation intermediate Download PDFInfo
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- CN115121083A CN115121083A CN202210824763.2A CN202210824763A CN115121083A CN 115121083 A CN115121083 A CN 115121083A CN 202210824763 A CN202210824763 A CN 202210824763A CN 115121083 A CN115121083 A CN 115121083A
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 423
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 193
- 230000006315 carbonylation Effects 0.000 title claims abstract description 61
- 238000005810 carbonylation reaction Methods 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 43
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims abstract description 154
- 239000001099 ammonium carbonate Substances 0.000 claims abstract description 154
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims abstract description 147
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims abstract description 147
- 238000000926 separation method Methods 0.000 claims abstract description 146
- 239000007788 liquid Substances 0.000 claims abstract description 130
- 239000007791 liquid phase Substances 0.000 claims abstract description 49
- 238000007906 compression Methods 0.000 claims abstract description 30
- 230000006835 compression Effects 0.000 claims abstract description 29
- 238000004064 recycling Methods 0.000 claims abstract description 3
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims description 80
- 238000003786 synthesis reaction Methods 0.000 claims description 37
- 230000015572 biosynthetic process Effects 0.000 claims description 34
- 238000009833 condensation Methods 0.000 claims description 31
- 230000005494 condensation Effects 0.000 claims description 31
- GWEHVDNNLFDJLR-UHFFFAOYSA-N Carbanilide Natural products C=1C=CC=CC=1NC(=O)NC1=CC=CC=C1 GWEHVDNNLFDJLR-UHFFFAOYSA-N 0.000 claims description 24
- 239000005416 organic matter Substances 0.000 claims description 23
- XKAFKUGMXFMRCC-UHFFFAOYSA-N 1,1-diphenylurea Chemical compound C=1C=CC=CC=1N(C(=O)N)C1=CC=CC=C1 XKAFKUGMXFMRCC-UHFFFAOYSA-N 0.000 claims description 19
- 239000012071 phase Substances 0.000 claims description 16
- 239000000945 filler Substances 0.000 claims description 15
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 13
- 239000011229 interlayer Substances 0.000 claims description 13
- 238000012856 packing Methods 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 239000004202 carbamide Substances 0.000 claims description 12
- 238000005507 spraying Methods 0.000 claims description 12
- 238000005192 partition Methods 0.000 claims description 10
- 235000012501 ammonium carbonate Nutrition 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 6
- 239000010410 layer Substances 0.000 claims description 5
- 239000007921 spray Substances 0.000 claims description 5
- AFBPFSWMIHJQDM-UHFFFAOYSA-N N-methylaniline Chemical compound CNC1=CC=CC=C1 AFBPFSWMIHJQDM-UHFFFAOYSA-N 0.000 claims description 4
- 238000003860 storage Methods 0.000 claims description 4
- 238000007751 thermal spraying Methods 0.000 claims description 4
- 239000001569 carbon dioxide Substances 0.000 claims description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000011084 recovery Methods 0.000 abstract description 16
- 238000000746 purification Methods 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 142
- 239000000047 product Substances 0.000 description 28
- 238000005406 washing Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000004140 cleaning Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 230000001376 precipitating effect Effects 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- YGYAWVDWMABLBF-UHFFFAOYSA-N Phosgene Chemical compound ClC(Cl)=O YGYAWVDWMABLBF-UHFFFAOYSA-N 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000012948 isocyanate Substances 0.000 description 2
- 150000002513 isocyanates Chemical class 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- KXDHJXZQYSOELW-UHFFFAOYSA-M Carbamate Chemical compound NC([O-])=O KXDHJXZQYSOELW-UHFFFAOYSA-M 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 238000006136 alcoholysis reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000000967 suction filtration Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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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 tail gas containing ammonia in a production process of a carbonylation intermediate, wherein the device sequentially comprises a gas-liquid separation unit, an ammonium bicarbonate trapping 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 trapping unit comprises an ammonium bicarbonate trapping 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 multistage separation unit, most 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 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 of easy blockage of a pipeline can be effectively solved, and the continuous and stable operation is realized for a long time.
Description
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 a carbonylation intermediate production process.
Background
Urea is a common product in the chemical industry, 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, the generated ammonia-containing tail gas needs to be separated and recovered, but because the characteristics of the urea such as easy moisture absorption, poor thermal stability and the like, ammonium bicarbonate can be carried in the ammonia gas, and the ammonium bicarbonate can be crystallized when being cooled, so that the tail gas pipeline is easily blocked, and the continuous production of the device is influenced.
At present, the industrial method for treating and recovering 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 heating the tail gas and then spraying water, so that the problem that the pipeline is blocked by ammonium bicarbonate in the spraying process can be avoided, but the process has high water consumption, and when the ammonia-containing gas phase contains an organic solvent, the problems that the ammonia water is unqualified or the pollutant discharged by the tail gas is not qualified and the like can be caused; the compression separation method is generally to liquefy ammonia gas to form liquid ammonia, but the method has low requirement on the inlet temperature of a compressor, is easy to cause the problem that ammonium bicarbonate blocks pipelines, and has high energy consumption.
For the application of urea in organic synthesis, such as the production of isocyanate by a non-phosgene method, the steps of urea carbonylation, alcoholysis, condensation, pyrolysis and the like are specifically 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, a solvent and ammonium bicarbonate are entrained, and effective components in ammonia-containing tail gas are separated and recovered, so that the method has an important influence on the stable production of the product.
CN 102001970A discloses a method for preparing diphenylurea by nitrogen gas stripping through direct reaction of urea and aniline, which 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 145-180 ℃, reacting at normal pressure for 2-6 h, stopping stirring after the reaction is finished, naturally cooling to crystallize, and carrying out suction filtration on a reaction crystallization product to obtain a crystalline diphenylurea product; the method mainly relates to the control of the preparation process of the diphenyl urea, and the subsequent treatment and recovery of ammonia-containing gas are not explicitly mentioned.
CN 110817900A discloses a separation device and a method for ammonia 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; the liquid ammonia product and the ammonium carbonate product are obtained through the steps of primary washing, secondary washing, pressurization, ammonia refining, organic matter separation, carbonization and filtration; the device has a complex structure and a plurality of operation steps, the treatment of ammonium bicarbonate possibly generated in the compression process is not clear, and the operation process is greatly influenced by organic components.
In conclusion, in the process of producing the carbonylation intermediate by the non-phosgene method, for the treatment of the tail gas containing ammonia, proper equipment and operation are required to be selected according to the composition of the tail gas, so that the high-efficiency 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 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, wherein the device is used for condensing and separating the ammonia-containing organic tail gas to obtain most of organic components through an ammonium bicarbonate trapping unit and a multistage separation unit, then separating out ammonium bicarbonate, and removing the rest of organic components through compression separation and tower separation, so that the separation and recovery of ammonia, organic components and ammonium bicarbonate in the tail gas from the synthesis of the carbonylation intermediate are realized, and the problem that a pipeline is easy to block can be effectively solved.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the invention provides a device for purifying and separating tail gas containing ammonia in a production process of a carbonylation intermediate, which sequentially comprises a gas-liquid separation unit, an ammonium bicarbonate trapping 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 trapping unit comprises an ammonium bicarbonate trap, 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 present invention, for the production of the carbonylation intermediate, particularly the intermediate for the production of isocyanates, for example, diphenyl urea, usually uses nitrogen-containing organic raw material, produces ammonia-containing tail gas after carbonylation, and based on the characteristics of the raw material, the tail gas also contains ammonium bicarbonate and organic components, the device of the invention is provided with a ammonium bicarbonate capturing unit and a multi-stage separation unit, wherein the ammonium bicarbonate capturing unit is arranged between the multi-stage separation units, most organic components are condensed and separated through a gas-liquid separation unit, ammonium bicarbonate is separated out through the structural design of an ammonium bicarbonate catcher, and the residual ammonia-containing gas is further separated out through compression separation and tower separation, so that the effective purification of the oxo-intermediate synthesis tail gas and the efficient recovery of ammonia, ammonium bicarbonate and organic components are realized, and the problem that the pipeline is easily blocked by ammonium bicarbonate is solved; the device has simple structure, can continuously and stably run for a long time, and has lower cost and high production efficiency.
The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.
As a preferred technical scheme of the invention, the ammonia-containing tail gas comes 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, wherein a gas phase outlet of the first condenser is connected to the second condenser, and a liquid phase outlet of the first condenser is connected to the carbonylation intermediate synthesis unit.
Preferably, the first condenser is a vertical condenser, the second condenser is a horizontal condenser, both the first condenser and the second condenser are shell-and-tube heat exchangers, and the ammonia-containing gas passes through a tube pass.
In the invention, the first condenser and the second condenser are used for cooling ammonia-containing gas at different temperature sections, so that different heat exchange media can be selected, for example, the first condenser is used for selecting heat conducting oil, and the second condenser is used for selecting circulating water.
Preferably, the first gas-liquid separator is a vertical tank, an outlet at the top of the first gas-liquid separator is connected with an inlet of the ammonium bicarbonate catcher, and an outlet at the bottom 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 being separated out in the pipeline in advance due to temperature reduction.
According to the preferred technical scheme, the ammonium bicarbonate catcher is a vertical heat exchanger, a U-shaped pipe is arranged in the ammonium bicarbonate catcher and serves 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.
Preferably, a partition plate is arranged in the middle of the ammonium bicarbonate trap along the longitudinal direction and extends to the bottom of the U-shaped pipe.
Preferably, the upper parts of the side surfaces of the ammonium bicarbonate catcher on the 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 is inclined downwards.
According to the invention, the horizontal or slightly-inclined lower baffle plate is arranged in the shell layer of the ammonium bicarbonate catcher, so that the ammonia-containing gas can be in full contact with the U-shaped pipe for heat exchange, and the crystallization is disturbed.
Preferably, an interlayer is arranged at the bottom of an upper end enclosure tube plate of the ammonium bicarbonate trap, a spraying hot medium inlet is formed in the side face of the interlayer, and a spraying port is formed in 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 spraying and washing, 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, such as one, two, three or four, and the ammonium bicarbonate traps are arranged in parallel and alternately operated when more than two ammonium bicarbonate traps are included.
In the invention, the ammonium bicarbonate catcher is used for catching ammonium bicarbonate during operation, the device is switched out to clean ammonium bicarbonate after operation is finished, a heat medium for cleaning ammonium bicarbonate can be steam or hot water and is uniformly sprayed on the U-shaped heat exchange tube, and the cleaning residual liquid is discharged from a boundary area to carry out 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 both vertical tanks, and the compressed ammonia-containing gas passes through the shell side 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 wire mesh corrugated packing.
Preferably, the top outlet of the ammonia separation tower is also connected with a tower top condenser, the bottom outlet of the ammonia separation tower is also connected with a tower kettle reboiler, and both the tower top condenser and the tower kettle reboiler are vertical heat exchangers.
Preferably, the overhead condenser obtains a liquid ammonia product, and the liquid ammonia product enters a liquid ammonia storage tank.
Preferably, the third gas-liquid separator is a vertical tank, an outlet at the top of the third gas-liquid separator is connected with an inlet at the lower part of the ammonia separation tower, and an outlet at the bottom of the third gas-liquid separator is connected with the carbonylation intermediate synthesis unit.
Preferably, the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator are connected to a confluence pipeline of the carbonylation intermediate synthesis unit, and a circulation pump is arranged on the confluence pipeline.
On the other hand, the invention provides a method for purifying and separating ammonia-containing tail gas in the production process of the carbonylation intermediate by adopting the device, which comprises the following steps:
(1) condensing the ammonia-containing tail gas, and then carrying out gas-liquid separation to obtain primary separated ammonia-containing tail gas and liquid-phase organic matters;
(2) carrying out ammonium bicarbonate capture 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 by thermal 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 (4) carrying out filler separation and gas-liquid separation on the tertiary ammonia-containing tail gas obtained in the step (3) to obtain purified gas and liquid-phase organic matter, and cooling the purified gas to obtain a liquid ammonia product.
As the preferred technical scheme of the invention, the source of the ammonia-containing tail gas in the step (1) comprises a production process of a carbonylation intermediate, preferably a process for producing N, N-diphenylurea by using urea and aniline as raw materials.
Preferably, the composition of the ammonia-containing tail gas in the step (1) comprises ammonia gas, ammonium bicarbonate, aniline, carbon dioxide and N-methylaniline.
Preferably, the temperature of the tail gas containing ammonia in the step (1) is 200 to 240 ℃, for example, 200 ℃, 205 ℃, 210 ℃, 215 ℃, 220 ℃, 225 ℃, 230 ℃, 235 ℃ or 240 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the condensation of step (1) comprises primary condensation and secondary condensation.
Preferably, the temperature of the ammonia-containing tail gas after the primary condensation is reduced to 100-140 ℃, for example, 100 ℃, 110 ℃, 120 ℃, 130 ℃ or 140 ℃, and the condensed liquid phase organic matter is returned to the production process of the carbonylation intermediate.
Preferably, the temperature of the ammonia-containing tail gas after the secondary condensation is reduced to 60-80 ℃, such as 60 ℃, 65 ℃, 70 ℃, 75 ℃ or 80 ℃, and the like, the liquid phase organic matter is continuously condensed, and the liquid phase organic matter is returned to the production process of the carbonylation intermediate after gas-liquid separation.
Preferably, the liquid phase organic matter separated after the condensation and the gas-liquid separation in step (1) accounts for 90 to 95% of the total amount of the liquid phase organic matter, for example, 90%, 91%, 92%, 93%, 94%, or 95%, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
In the invention, the condensation process comprises primary condensation and secondary condensation, wherein the liquid-phase organic matter obtained through the primary condensation accounts for 80-90% of the total amount of the liquid-phase organic matter, such as 80%, 82%, 85%, 88% or 90%, and the like, and the liquid-phase organic matter obtained through the secondary condensation and gas-liquid separation is liquefied once again, and the liquid-phase organic matter separated after the secondary condensation accounts for 90-95% of the total amount of the organic matter.
In a preferred embodiment of the present invention, the ammonium bicarbonate trapping in step (2) is performed in an ammonium bicarbonate trap.
Preferably, in the ammonium bicarbonate collection, the temperature of the primarily separated ammonia-containing tail gas is continuously reduced to below 40 ℃, for example, 40 ℃, 38 ℃, 35 ℃, 32 ℃, 30 ℃ or 25 ℃, and ammonium bicarbonate is precipitated on the U-shaped pipe in the ammonium bicarbonate collector.
Preferably, when the number of the ammonium bicarbonate traps comprises more than two, the operation is alternated.
Preferably, the thermal spraying in the step (2) is to perform spray rinsing by using a thermal medium to dissolve and remove precipitated ammonium bicarbonate.
Preferably, the heat medium comprises steam or hot water, and the removal time is not more than 0.5h, such as 0.5h, 0.45h, 0.4h, 0.35h, 0.3h, 0.25h, or 0.2h, and the like, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.
In the invention, the top of the ammonium bicarbonate catcher is provided with a hot medium spray, the hot medium is hot water or low-pressure steam, such as 80 ℃ hot water or 0.2MPaG steam, the ammonium bicarbonate has low melting point and is easy to dissolve in water, the ammonium bicarbonate can be rapidly decarburized in the system cutting stage of equipment, and the required time is short.
In a preferred embodiment of the present invention, the pressure of the secondary separated ammonia-containing off gas in 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, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable.
Preferably, the temperature of the ammonia-containing tail gas subjected to secondary separation after compression is increased, and gas-liquid separation is performed after cooling again.
Preferably, after the gas-liquid separation in the step (3), the liquid phase organic matter is returned to the production process of the carbonylation intermediate.
Preferably, the pressure of the ammonia-containing tail gas after the gas-liquid separation in the step (3) and three times of separation is 2.6 to 3.2MPaG, such as 2.6MPaG, 2.7MPaG, 2.8MPaG, 2.9MPaG, 3.0MPaG, 3.1MPaG, or 3.2MPaG, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
As a preferred technical scheme of the invention, the packing separation in the step (4) is carried out in an ammonia separation tower.
Preferably, the packing in the ammonia separation column comprises pall rings and/or wire mesh corrugated packing.
Preferably, the pressure for separating the packing 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, and the temperature is 60 to 70 ℃, such as 60 ℃, 62 ℃, 64 ℃, 66 ℃, 68 ℃ or 70 ℃, but not limited to the recited values, and other values not recited in the respective numerical ranges are also applicable.
Preferably, during the filler separation in the step (4), the ammonia-containing tail gas after the third separation is partially liquefied, the unliquefied gas phase leaves from the top of the tower, and the liquefied organic matter is heated in the tower kettle to be subjected to gas-liquid separation again.
Preferably, the purified gas in step (4) is cooled to 40-60 ℃ to obtain a liquid ammonia product, such as 40 ℃, 45 ℃, 50 ℃, 55 ℃ or 60 ℃, but not limited to the values listed, and other values not listed in the range of the values are also 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 matter separated in the steps (3) and (4) is decompressed to 0-0.5 MPaG, for example, 0MPaG, 0.1MPaG, 0.2MPaG, 0.3MPaG, 0.4MPaG or 0.5MPaG, and then mixed with the liquid phase organic matter separated in the step (1), and then transported to the carbonylation intermediate synthesis unit.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the device, through the arrangement of the ammonium bicarbonate trapping unit and the multistage separation unit, most organic components are condensed and separated through the gas-liquid separation unit, then ammonium bicarbonate is separated out through the structural design of the ammonium bicarbonate trapping unit, the residual ammonia-containing gas is further separated out through compression separation and tower separation, the effective purification of the synthetic tail gas of the carbonylation intermediate and the efficient recovery of ammonia, ammonium bicarbonate and the organic components are realized, the ammonium bicarbonate removal rate reaches more than 99.5%, the recovery rate of the organic components reaches more than 99.9%, and the purity of a liquid ammonia product reaches more than 99.9%;
(2) the device can effectively solve the problem that ammonium bicarbonate is easy to cause pipeline blockage, can continuously and stably run for more than 3000 hours, and has low equipment cost and high production efficiency.
Drawings
FIG. 1 is a schematic structural diagram of an apparatus for purifying and separating ammonia-containing tail gas in a carbonylation intermediate production process provided in example 1 of the present invention;
FIG. 2 is a schematic structural diagram of an ammonium bicarbonate trap provided in embodiment 1 of the present invention;
the device comprises a condenser, a condenser and a carbonylation intermediate synthesis unit, wherein the condenser comprises 1-a first condenser, 2-a second condenser, 3-a first gas-liquid separator, 4-an ammonium carbonate catcher, 41-a U-shaped pipe, 42-a clapboard, 43-a baffle plate, 44-an interlayer, 45-a spraying opening, 5-a compressor, 6-a cooler, 7-a second gas-liquid separator, 8-an ammonia separation tower, 9-a third gas-liquid separator and 10-a carbonylation intermediate synthesis unit.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.
The following are typical but non-limiting examples of the invention:
example 1:
the embodiment provides a device that contains ammonia tail gas clean-up separation in carbonylation intermediate production process, the structural schematic diagram of device is shown in fig. 1, includes gas-liquid separation unit, ammonium bicarbonate entrapment unit, compression separation unit and ammonia separation unit in proper order, the gas-liquid separation unit includes condenser and first vapour and liquid separator 3, ammonium bicarbonate entrapment unit includes ammonium bicarbonate trapper 4, the compression separation unit includes compressor 5 and second vapour and liquid separator 7, the ammonia separation unit includes ammonia knockout tower 8 and third vapour and liquid separator 9, the liquid phase exit linkage of first vapour and liquid separator 3, second vapour and liquid separator 7 and third vapour and liquid separator 9 is to same pipeline retrieval and utilization.
The ammonia-containing tail gas comes from a carbonylation intermediate synthesis unit 10, specifically an N, N-diphenylurea synthesis unit.
The condenser comprises a first condenser 1 and a second condenser 2, wherein a gas phase outlet of the first condenser 1 is connected to the second condenser 2, and a 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, both the first condenser and the second condenser are shell-and-tube heat exchangers, and the ammonia-containing gas passes through a tube pass.
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 structural diagram of the ammonium bicarbonate trap 4 is shown in fig. 2, the ammonium bicarbonate trap 4 is a vertical heat exchanger, a U-shaped pipe 41 is arranged inside the ammonium bicarbonate trap and serves 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 both arranged at the top of the ammonium bicarbonate trap 4.
A partition plate 42 is arranged in the middle of the ammonium bicarbonate catcher 4 along the longitudinal direction, and the partition plate 42 extends to the bottom of the U-shaped pipe 41; and the upper parts of the side surfaces of the ammonium bicarbonate catcher 4 at 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 an upper end socket tube plate of the ammonium carbonate trap 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 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 type compressor.
The compression and separation unit further comprises a cooler 6, the cooler 6 being arranged between the compressor 5 and the second gas-liquid separator 7.
The cooler 6 and the second gas-liquid separator 7 are both 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 the carbonylation intermediate synthesis unit 10.
The ammonia separation column 8 comprises a packed column 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 tower top condenser and the tower kettle reboiler are both vertical heat exchangers; and 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, an outlet at the top of the third gas-liquid separator 9 is connected with an inlet at the lower part of the ammonia separation tower 8, and an outlet at the bottom of the third gas-liquid separator 9 is connected with the carbonylation intermediate synthesis unit 10.
And 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 a circulating pump is arranged on the converging pipeline.
Example 2:
the embodiment provides a device that contains ammonia tail gas clean-up separation in carbonylation intermediate production process, the device includes gas-liquid separation unit, ammonium bicarbonate entrapment unit, compression separation unit and ammonia separation unit in proper order, the gas-liquid separation unit includes condenser and first vapour and liquid separator 3, ammonium bicarbonate entrapment unit includes ammonium bicarbonate trap 4, the compression separation unit includes compressor 5 and second vapour and liquid separator 7, the ammonia separation unit includes ammonia knockout tower 8 and third vapour and liquid separator 9, the liquid phase exit linkage of first vapour and liquid separator 3, second vapour and liquid separator 7 and third vapour and liquid separator 9 is to same pipeline retrieval and utilization.
The ammonia-containing tail gas comes from a carbonylation intermediate synthesis unit 10, specifically an N, N-diphenylurea synthesis unit.
The condenser comprises a first condenser 1 and a second condenser 2, wherein a gas phase outlet of the first condenser 1 is connected to the second condenser 2, and a 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, both the first condenser and the second condenser are shell-and-tube heat exchangers, and ammonia-containing gas passes through a tube pass.
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 trap 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 inside the ammonium bicarbonate catcher and serves 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 both arranged at the top of the ammonium bicarbonate catcher 4.
A partition plate 42 is arranged in the middle of the ammonium bicarbonate catcher 4 along the longitudinal direction, and the partition plate 42 extends to the bottom of the U-shaped pipe 41; and the upper parts of the side surfaces of the ammonium bicarbonate catcher 4 at 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 manner.
An interlayer 44 is arranged at the bottom of an upper end socket tube plate of the ammonium bicarbonate trap 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, the three traps are arranged in parallel and operate alternately.
The compressor 4 is a centrifugal compressor.
The compression and separation unit further comprises a cooler 6, the cooler 6 being arranged between the compressor 5 and the second gas-liquid separator 7.
The cooler 6 and the second gas-liquid separator 7 are both vertical tanks, and the compressed ammonia-containing gas passes through the shell side of the cooler 6.
The liquid phase outlet of the second gas-liquid separator 7 is connected to the 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 tower top condenser and the tower kettle reboiler are both vertical heat exchangers; and the condenser at the tower top 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, an outlet at the top of the third gas-liquid separator 9 is connected with an inlet at the lower part of the ammonia separation tower 8, and an outlet at the bottom 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 a production process of a carbonylation intermediate, which is carried out by adopting the device in the embodiment 1 and comprises the following steps:
(1) condensing ammonia-containing tail gas, and then carrying out gas-liquid separation on the ammonia-containing tail gas, wherein the source of the ammonia-containing tail gas is a process for producing N, N-diphenylurea by using urea and aniline as raw materials, and the ammonia-containing tail gas comprises 30 wt% of ammonia gas, 67 wt% of aniline and 100g/m of aniline 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 after gas-liquid separation, the condensed aniline accounts for 95 percent of the total aniline amount, and the condensed aniline returns to the production process of N, N-diphenylurea, and the primary separated ammonia-containing tail gas is obtained;
(2) enabling the primary separated ammonia-containing tail gas obtained in the step (1) to enter an ammonium bicarbonate trap 4 for ammonium bicarbonate trapping, continuously cooling the primary separated ammonia-containing tail gas to 38 ℃, and precipitating ammonium bicarbonate out of a U-shaped pipe 41 in the ammonium bicarbonate trap 4 to obtain secondary separated ammonia-containing tail gas; the ammonium bicarbonate product is subjected to spray rinsing by adopting steam, and the precipitated ammonium bicarbonate is dissolved and removed for 0.4 h;
(3) compressing the secondary separated ammonia-containing tail gas obtained in the step (2), wherein the pressure before compression is 0.1MPaG, raising the temperature of the secondary separated ammonia-containing tail gas after compression, cooling again, and then carrying out gas-liquid separation to obtain tertiary separated ammonia-containing tail gas and liquid phase aniline, wherein 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-diphenylurea after being decompressed to 0.3 MPaG;
(4) and (3) performing filler separation on the tertiary 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 pall ring, the pressure of the filler separation is 2.9MPaG, the temperature is 66 ℃, the tertiary ammonia-containing tail gas is partially liquefied, the unliquefied 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 and is subjected to 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 decompressed to 0.3 MPaG.
In the embodiment, the device and the method are adopted to purify and separate the ammonia-containing tail gas, according to the ammonium bicarbonate content and the aniline recovery amount in the residual tail gas in the step (2), the ammonium bicarbonate removal rate reaches 99.97%, the aniline recovery rate reaches 99.92%, the purity of a liquid ammonia product can reach 99.95%, and the continuous 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 a production process of a carbonylation intermediate, which is carried out by adopting the device in the embodiment 1 and comprises the following steps:
(1) condensing ammonia-containing tail gas, and then carrying out gas-liquid separation on the ammonia-containing tail gas, wherein the source of the ammonia-containing tail gas is a process for producing N, N-diphenylurea by using urea and aniline as raw materials, and the ammonia-containing tail gas comprises 35 wt% of ammonia gas, 60 wt% of aniline and 80g/m of aniline 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 percent of the total amount of aniline after gas-liquid separation and returns to the production process of N, N-diphenylurea to obtain the primary separated ammonia-containing tail gas;
(2) enabling the primary separated ammonia-containing tail gas obtained in the step (1) to enter an ammonium bicarbonate trap 4 for ammonium bicarbonate trapping, continuously cooling the primary separated ammonia-containing tail gas to 40 ℃, and precipitating ammonium bicarbonate out of a U-shaped pipe 41 in the ammonium bicarbonate trap 4 to obtain secondary separated ammonia-containing tail gas; the ammonium bicarbonate product is subjected to spray rinsing by adopting steam, and the precipitated ammonium bicarbonate is dissolved and removed for 0.5 h;
(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 again and then performing gas-liquid separation to obtain tertiary separated ammonia-containing tail gas and liquid phase aniline, wherein the pressure of the tertiary separated ammonia-containing tail gas is 3.0MPaG, and the aniline is returned to the production process of N, N-diphenylurea after being decompressed to 0.5 MPaG;
(4) and (3) performing filler separation on the tertiary 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 pall ring, the pressure of the filler separation is 3.0MPaG, the temperature is 70 ℃, the tertiary ammonia-containing tail gas is partially liquefied, the unliquefied 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 and is subjected to 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 decompressed to 0.5 MPaG.
In the embodiment, the device and the method are adopted to purify and separate the ammonia-containing tail gas, according to the ammonium bicarbonate content and the aniline recovery amount in the residual tail gas in the step (2), the ammonium bicarbonate removal rate reaches 99.92%, the aniline recovery rate reaches 99.94%, the purity of a liquid ammonia product can reach 99.93%, and the continuous stable operation time of the device reaches 3100 h.
Example 5:
the embodiment provides a method for purifying and separating ammonia-containing tail gas in a production process of a carbonylation intermediate, which is performed by using the device in embodiment 2 and comprises the following steps:
(1) condensing ammonia-containing tail gas, and then carrying out gas-liquid separation on the ammonia-containing tail gas, wherein the source of the ammonia-containing tail gas is a process for producing N, N-diphenylurea by using urea and aniline as raw materials, and the ammonia-containing tail gas comprises 40 wt% of ammonia gas, 57.5 wt% of aniline and 90g/m of aniline 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 percent of the total amount of aniline after gas-liquid separation and returns to the production process of N, N-diphenylurea to obtain the primary separated ammonia-containing tail gas;
(2) enabling the primary separated ammonia-containing tail gas obtained in the step (1) to enter an ammonium bicarbonate trap 4 for ammonium bicarbonate trapping, continuously cooling the primary separated ammonia-containing tail gas to 35 ℃, and precipitating ammonium bicarbonate out of a U-shaped pipe 41 in the ammonium bicarbonate trap 4 to obtain secondary separated ammonia-containing tail gas; the ammonium bicarbonate product is sprayed and washed by hot water at 80 ℃, and the precipitated ammonium bicarbonate is dissolved and removed for 0.3 h;
(3) compressing the secondary separated ammonia-containing tail gas obtained in the step (2), wherein the pressure before compression is 0.2MPaG, raising the temperature of the secondary separated ammonia-containing tail gas after compression, cooling again, and then carrying out gas-liquid separation to obtain tertiary separated ammonia-containing tail gas and liquid phase aniline, wherein the pressure of the tertiary separated ammonia-containing tail gas is 3.2MPaG, and the aniline is returned to the production process of N, N-diphenylurea after being decompressed to 0.1 MPaG;
(4) and (3) performing filler separation on the tertiary 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 a wire mesh corrugated filler, the pressure of the filler separation is 3.2MPaG, the temperature is 60 ℃, the tertiary ammonia-containing tail gas is partially liquefied, the unliquefied 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 and is subjected to 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-diphenylurea after being decompressed to 0.1 MPaG.
In the embodiment, the device and the method are adopted to purify and separate the ammonia-containing tail gas, according to the ammonium bicarbonate content and the aniline recovery amount in the residual tail gas in the step (2), the ammonium bicarbonate removal rate reaches 99.9%, the aniline recovery rate reaches 99.91%, the purity of a liquid ammonia product can reach 99.92%, and the continuous stable operation time of the device reaches 3200 h.
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 intermediate, which is similar to the apparatus in example 1 except that: the ammonium carbonate trap 4 is replaced by a conventional shell-and-tube heat exchanger.
The process is referred to the process in example 3, with the only difference that: and (3) carrying out heat exchange and cooling on the ammonia-containing tail gas separated in the step (2) by using a shell-and-tube heat exchanger to separate out ammonium bicarbonate.
In this comparative example, owing to not set up the ammonium bicarbonate trap, ammonium bicarbonate is appeared in conventional heat exchanger, causes the inside jam that piles up of heat exchanger easily, and is difficult to directly drip washing, and every operation a period of time needs to be suspended, unable long-time steady operation, and along with time lapse, the heat transfer effect reduces, is difficult to realize fully appearing of ammonium bicarbonate, influences follow-up separation process.
It can be seen from the above examples and comparative examples that, the device of the present invention, through the arrangement of the ammonium bicarbonate trapping unit and the multistage separation unit, firstly, through the gas-liquid separation unit, most of the organic components are condensed and separated, then, through the structural design of the ammonium bicarbonate trapping unit, ammonium bicarbonate is separated out, the remaining ammonia-containing gas is further separated out through compression separation and tower separation, thereby realizing the effective purification of the carbonylation intermediate synthesis tail gas and the efficient recovery of ammonia, ammonium bicarbonate and organic components, the ammonium bicarbonate removal rate reaches more than 99.5%, the recovery rate of the organic components reaches more than 99.9%, and the purity of the liquid ammonia product reaches more than 99.9%; the device can effectively solve the problem that ammonium bicarbonate easily causes pipeline blockage, can continuously and stably operate for more than 3000 hours, and has the advantages of low equipment cost and high production efficiency.
The present invention is illustrated by the above-described embodiments of the detailed apparatus and method of the present invention, but the present invention is not limited to the above-described detailed apparatus and method, i.e., it is not intended that the present invention be implemented by relying on the above-described detailed apparatus and method. It should be understood by those skilled in the art that any modifications, equivalent substitutions of the device of the present invention, additions of auxiliary devices, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. The device for purifying and separating the tail gas containing ammonia in the production process of the carbonylation intermediate is characterized by sequentially comprising a gas-liquid separation unit, an ammonium bicarbonate collecting 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 trapping unit comprises an ammonium bicarbonate trap, 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.
2. The device according to claim 1, wherein the ammonia-containing tail gas is from a carbonylation intermediate synthesis unit, preferably an N, N-diphenylurea synthesis unit;
preferably, the condenser comprises a first condenser and a second condenser, wherein a gas phase outlet of the first condenser is connected to the second condenser, and a liquid phase outlet of the first condenser is connected to the carbonylation intermediate synthesis unit;
preferably, the first condenser is a vertical condenser, the second condenser is a horizontal condenser, both the first condenser and the second condenser are shell-and-tube heat exchangers, and the ammonia-containing gas passes through a tube pass;
preferably, the first gas-liquid separator is a vertical tank, an outlet at the top of the first gas-liquid separator is connected with an inlet of the ammonium bicarbonate catcher, and an outlet at the bottom of the first gas-liquid separator is connected with the carbonylation intermediate synthesis unit.
3. The device according to claim 1 or 2, wherein the ammonium bicarbonate catcher is a vertical heat exchanger, a U-shaped pipe is arranged in the ammonium bicarbonate catcher and serves as a pipe pass, and a heat exchange medium passes through the pipe pass;
preferably, a partition plate is arranged in the middle of the ammonium bicarbonate catcher along the longitudinal direction and extends to the bottom of the U-shaped pipe;
preferably, the upper parts of the side surfaces of the ammonium bicarbonate catcher on the 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 a shell layer of the ammonium bicarbonate catcher, and the baffle plate is horizontally arranged or inclined downwards;
preferably, an interlayer is arranged at the bottom of an upper end socket tube plate of the ammonium bicarbonate trap, a spraying heat medium inlet is arranged on the side surface of the interlayer, and a spraying port is arranged at the bottom of the interlayer;
preferably, the number of the ammonium bicarbonate catcher is at least one, and when the number of the ammonium bicarbonate catchers is more than two, the ammonium bicarbonate catchers are arranged in parallel and run alternately.
4. The apparatus of any one of claims 1-3, wherein the compressor comprises a screw-type 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 both vertical tanks, and the compressed ammonia-containing gas passes through the shell side of the cooler;
preferably, the liquid phase outlet of the second gas-liquid separator is connected to a carbonylation intermediate synthesis unit.
5. The apparatus of any one of claims 1-4, wherein the ammonia separation column comprises a packed column, the packing comprising pall rings and/or wire mesh corrugated packing;
preferably, the top outlet of the ammonia separation tower is also connected with a tower top condenser, the bottom outlet of the ammonia separation tower is also connected with a tower kettle reboiler, and both the tower top condenser and the tower kettle reboiler are vertical heat exchangers;
preferably, the overhead condenser obtains a liquid ammonia product, and the liquid ammonia product enters a liquid ammonia storage tank;
preferably, the third gas-liquid separator is a vertical tank, an outlet at the top of the third gas-liquid separator is connected with an inlet at the lower part of the ammonia separation tower, and an outlet at the bottom of the third gas-liquid separator is connected with the carbonylation intermediate synthesis unit;
preferably, the first gas-liquid separator, the second gas-liquid separator and the third gas-liquid separator are connected to a confluence pipeline of the carbonylation intermediate synthesis unit, and a circulation pump is arranged on the confluence pipeline.
6. A method for purifying and separating ammonia-containing tail gas in the production process of an oxo intermediate by using the device of any one of claims 1 to 5, which is characterized by comprising the following steps:
(1) condensing the ammonia-containing tail gas, and then carrying out gas-liquid separation to obtain primary separated ammonia-containing tail gas and liquid-phase organic matters;
(2) carrying out ammonium carbonate capture on the primary separated ammonia-containing tail gas obtained in the step (1) to obtain secondary separated ammonia-containing tail gas and an ammonium carbonate product, wherein the ammonium carbonate product is removed by thermal 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 (4) carrying out filler separation and gas-liquid separation on the tertiary ammonia-containing tail gas obtained in the step (3) to obtain purified gas and liquid-phase organic matter, and cooling the purified gas to obtain a liquid ammonia product.
7. The method according to claim 6, wherein the source of the ammonia-containing tail gas in step (1) comprises a carbonylation intermediate production process, preferably a process for producing N, N-diphenylurea by using urea and aniline as raw materials;
preferably, the composition of the ammonia-containing tail gas in the step (1) comprises ammonia gas, ammonium bicarbonate, aniline, carbon dioxide and N-methylaniline;
preferably, the temperature of the ammonia-containing tail gas in the step (1) is 200-240 ℃;
preferably, the condensing of step (1) comprises a primary condensing and a secondary condensing;
preferably, the temperature of the ammonia-containing tail gas after primary condensation is reduced to 100-140 ℃, and the condensed liquid phase organic matter is 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 ℃, 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 the gas-liquid separation in the step (1), the separated liquid-phase organic matters account for 90-95% of the total amount of the liquid-phase organic matters.
8. The method according to claim 6 or 7, wherein the ammonium bicarbonate capture of step (2) is performed in an ammonium bicarbonate trap;
preferably, during ammonium bicarbonate capture, the primary separated ammonia-containing tail gas is continuously cooled to below 40 ℃, and ammonium bicarbonate is precipitated on a U-shaped pipe in the ammonium bicarbonate trap;
preferably, when the number of the ammonium bicarbonate traps comprises more than two, the ammonium bicarbonate traps alternately operate;
preferably, the thermal spraying in the step (2) is to perform spray rinsing by adopting a thermal medium to dissolve and remove precipitated ammonium bicarbonate;
preferably, the heat medium comprises steam or hot water, and the removal time is not more than 0.5 h.
9. The method according to any one of claims 6 to 8, wherein the pressure of the secondary separation ammonia-containing tail gas in the step (3) is 0.05 to 0.2 MPaG;
preferably, the temperature of the ammonia-containing tail gas subjected to secondary separation after compression is increased, and gas-liquid separation is performed after cooling is performed again;
preferably, after the gas-liquid separation in the step (3), the liquid phase organic matter returns to the production process of the carbonylation intermediate;
preferably, the pressure of the ammonia-containing tail gas subjected to the third separation after the gas-liquid separation in the step (3) is 2.6-3.2 MPaG.
10. The process of any one of claims 6-9, wherein the packing separation of 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 for separating the filler in the step (4) is 2.6-3.2 MPaG, and the temperature is 60-70 ℃;
preferably, when the filler is separated in the step (4), the ammonia-containing tail gas separated for the third time is partially liquefied, the unliquefied gas phase leaves from the top of the tower, and the liquefied organic matter is heated in the tower kettle to be subjected to gas-liquid separation again;
preferably, the purified gas in the step (4) is cooled to 40-60 ℃ to obtain a liquid ammonia product;
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 the steps (3) and (4) are decompressed to 0-0.5 MPaG, mixed with the liquid phase organic matters separated in the step (1), and conveyed to the carbonylation intermediate synthesis unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210824763.2A CN115121083B (en) | 2022-07-13 | 2022-07-13 | Device and method for purifying and separating ammonia-containing tail gas in carbonylation intermediate production process |
Applications Claiming Priority (1)
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| CN202210824763.2A CN115121083B (en) | 2022-07-13 | 2022-07-13 | Device and method for purifying and separating ammonia-containing tail gas in carbonylation intermediate production process |
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| CN115121083B (en) | 2024-03-01 |
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