CN117619110A - Flue gas decarburization system and process for purifying natural gas - Google Patents
Flue gas decarburization system and process for purifying natural gas Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 118
- 239000003345 natural gas Substances 0.000 title claims abstract description 59
- 238000000034 method Methods 0.000 title claims abstract description 46
- 230000008569 process Effects 0.000 title claims abstract description 42
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 34
- 239000003546 flue gas Substances 0.000 title claims abstract description 34
- 238000005261 decarburization Methods 0.000 title claims abstract description 14
- 239000007789 gas Substances 0.000 claims abstract description 242
- 239000002253 acid Substances 0.000 claims abstract description 101
- 238000010521 absorption reaction Methods 0.000 claims abstract description 64
- 239000007788 liquid Substances 0.000 claims abstract description 61
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 58
- 230000008929 regeneration Effects 0.000 claims abstract description 42
- 238000011069 regeneration method Methods 0.000 claims abstract description 42
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 35
- 239000011593 sulfur Substances 0.000 claims abstract description 35
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 34
- 230000023556 desulfurization Effects 0.000 claims abstract description 34
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 29
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 29
- 238000011084 recovery Methods 0.000 claims abstract description 27
- 229910000037 hydrogen sulfide Inorganic materials 0.000 claims abstract description 20
- 239000002904 solvent Substances 0.000 claims abstract description 19
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 13
- 150000003568 thioethers Chemical class 0.000 claims abstract description 5
- 238000005262 decarbonization Methods 0.000 claims description 32
- 238000000746 purification Methods 0.000 claims description 17
- 239000000243 solution Substances 0.000 claims description 14
- 238000002485 combustion reaction Methods 0.000 claims description 12
- -1 alcohol amine Chemical class 0.000 claims description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- YQCIWBXEVYWRCW-UHFFFAOYSA-N methane;sulfane Chemical compound C.S YQCIWBXEVYWRCW-UHFFFAOYSA-N 0.000 claims description 6
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 5
- 150000001412 amines Chemical class 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 5
- CRVGTESFCCXCTH-UHFFFAOYSA-N methyl diethanolamine Chemical group OCCN(C)CCO CRVGTESFCCXCTH-UHFFFAOYSA-N 0.000 claims description 5
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 4
- GVGLGOZIDCSQPN-PVHGPHFFSA-N Heroin Chemical compound O([C@H]1[C@H](C=C[C@H]23)OC(C)=O)C4=C5[C@@]12CCN(C)[C@@H]3CC5=CC=C4OC(C)=O GVGLGOZIDCSQPN-PVHGPHFFSA-N 0.000 claims description 4
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 238000010791 quenching Methods 0.000 claims description 4
- 230000000171 quenching effect Effects 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 238000001704 evaporation Methods 0.000 claims description 3
- 230000008020 evaporation Effects 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 230000001172 regenerating effect Effects 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 2
- 230000009467 reduction Effects 0.000 claims description 2
- 150000003512 tertiary amines Chemical class 0.000 claims description 2
- 230000003009 desulfurizing effect Effects 0.000 claims 2
- 125000003277 amino group Chemical group 0.000 claims 1
- 238000009472 formulation Methods 0.000 claims 1
- 150000003335 secondary amines Chemical class 0.000 claims 1
- 229910052799 carbon Inorganic materials 0.000 abstract description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 12
- 239000006096 absorbing agent Substances 0.000 abstract 1
- 238000004064 recycling Methods 0.000 description 9
- 101000720907 Pseudomonas savastanoi pv. phaseolicola Ornithine carbamoyltransferase 1, anabolic Proteins 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007701 flash-distillation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 150000003141 primary amines Chemical class 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/40—Capture or disposal of greenhouse gases of CO2
Abstract
The invention discloses a flue gas decarburization system and a flue gas decarburization process for purifying natural gas, wherein the flue gas decarburization system comprises a natural gas desulfurization unit, a sulfur recovery unit, a tail gas treatment unit and an acid gas concentration unit; the tail gas treatment unit comprises a tail gas hydrogenation reactor, a tail gas absorption tower and a tail gas regeneration tower; the acid gas concentration unit comprises an acid gas absorption tower and an acid gas regeneration tower; the tail gas absorption tower removes carbon dioxide and a small amount of sulfides in the tail gas by using a full-stripping solvent, and then the rich liquid is regenerated to obtain a high-carbon sulfur ratio acid gas flow; the acid gas absorption tower removes hydrogen sulfide of high-carbon sulfur ratio acid gas by utilizing the selective absorption type desulfurization solvent to obtain high-concentration carbon dioxide gas flow. According to the invention, an original tail gas treatment unit is utilized, after the absorber is reformed, a full-stripping solvent is adopted to remove carbon dioxide and a small amount of hydrogen sulfide in sulfur recovery tail gas, a low-flow high-carbon-sulfur-ratio sour gas is obtained through regeneration, and then a sour gas concentration device is utilized to selectively absorb the sour gas to obtain a high-concentration carbon dioxide gas flow, so that decarburization treatment and high-efficiency carbon capture are completed.
Description
Technical Field
The invention relates to the technical field of natural gas purification, in particular to a flue gas decarbonization system and a flue gas decarbonization process for natural gas purification.
Background
The alcohol amine method is a mainstream technology of carbon capture of the flue gas after combustion at present, wherein a decarburization device mainly comprises an absorption unit, a regeneration unit and a heat exchange unit, and the conventional process flow is as follows: the flue gas is pretreated, dedusted and cooled, and then contacts with decarbonizing solution in an absorption tower to remove CO therein 2 The gas passes through the purification gas separator and then enters the discharge chimney. And (3) heating the rich amine liquid at the bottom of the decarburization absorption tower through heat exchange, and then, feeding the rich amine liquid into a regeneration tower to regenerate high-temperature desulfurization lean liquid, and cooling the lean liquid to the decarburization absorption tower for recycling. Cooling the acid gas obtained by the rich liquid regeneration, and then delivering the cooled acid gas to a subsequent dehydration and compression device for CO 2 Storing and utilizing.
For a natural gas purification plant, the flue gas is the exhaust gas after desulfurization, sulfur recovery and tail gas treatment. At present, the flue gas of the domestic natural gas purification plant is directly discharged after the tail gas is desulfurized and is not subjected to carbon capture. At present, for the decarbonization treatment of the flue gas after natural gas purification, the residual sulfide in the tail gas is further removed and recovered in a tail gas treatment unit, and then enters a decarbonization device for decarbonization treatment. For a natural gas purification plant with the scale of over 200 square meters per day, the flue gas flow is large and is 20000-40000 square meters per hour; the pressure is low, close to atmospheric pressure. Thus in order to ensure a higher CO 2 The removal rate needs higher solution circulation quantity, so that the scale and investment of a decarburization device are larger, and the carbon capturing economy is poorer.
In view of this, the present application is specifically proposed.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a flue gas decarbonization system and a flue gas decarbonization process for purifying natural gas, which are characterized in that the absorption process of an absorption tower in an original natural gas tail gas treatment unit is improved, most of carbon dioxide and a small amount of hydrogen sulfide in sulfur recovery tail gas are removed by adopting a full-stripping solvent, a small-flow high-carbon sulfur ratio acid gas is obtained through regeneration, and then the acid gas is selectively absorbed by utilizing an additionally added acid gas concentration unit to obtain a high-concentration carbon dioxide gas flow.
The invention is realized by the following technical scheme:
a decarbonization system for purifying natural gas comprises a natural gas desulfurization unit, a sulfur recovery unit, a tail gas treatment unit and an acid gas concentration unit which are connected in sequence;
the natural gas desulfurization unit comprises a natural gas absorption tower, a flash distillation tower, a regeneration tower, a purification gas separator, an acid gas separator, a lean-rich liquid heat exchanger, a lean liquid cooler, an acid gas air cooler and a lean liquid pump;
the sulfur recovery unit includes: a burner, a claus reactor, and a sulfur condenser;
the exhaust gas treatment unit includes: the device comprises a tail gas hydrogenation reactor, a tail gas quenching tower, a tail gas absorption tower, a tail gas regeneration tower, a purification gas separator, an acid gas separator, a lean-rich liquid heat exchanger, a lean liquid cooler, an acid gas air cooler, a lean liquid pump, a rich liquid pump and a tail gas incinerator;
the acid gas concentration unit includes: an acid gas absorption tower, an acid gas regeneration tower, a lean-rich liquid heat exchanger, a reboiler, an acid gas cooler, a lean liquid pump and a rich liquid pump;
the natural gas desulfurization unit adopts an alcohol amine method process or a derivative process thereof for desulfurization, and can adopt a multi-stage feeding and double-tower absorption mode;
the sulfur recovery unit adopts a conventional Claus process and a derivative process thereof, and adopts a two-stage or three-stage Claus reactor;
the tail gas treatment unit adopts a mode of combining a SCOT hydrogenation reduction absorption process or a derivative process thereof with an alcohol amine process or a derivative process thereof to realize removal of carbon dioxide and a small amount of sulfides in the tail gas and regeneration of a high-carbon sulfur ratio acid gas flow by rich liquor, and the tail gas treatment unit also adopts multistage feeding and double-tower absorption;
the acid gas concentration unit adopts an alcohol amine method process or a derivative process thereof to remove hydrogen sulfide in the high-carbon sulfur ratio acid gas flow to obtain a high-concentration carbon dioxide gas flow, and the acid gas concentration unit can adopt multi-stage feeding and double-tower absorption;
wherein, the gas outlet pipeline of the final stage claus reactor of the sulfur recovery unit is connected with the inlet pipeline of the tail gas hydrogenation reactor of the tail gas treatment unit;
an acid gas outlet pipeline of the tail gas regeneration tower of the tail gas treatment unit is connected with a gas inlet pipeline of an acid gas absorption tower in the acid gas concentration unit;
the gas outlet pipeline of the acid gas regeneration tower of the acid gas concentration unit is connected with the inlet pipeline of the combustion furnace of the sulfur recovery unit.
The invention also provides a decarbonization process for purifying natural gas, which comprises the following specific steps:
1) Introducing natural gas from the bottom of a natural gas absorption tower, carrying out countercurrent contact with desulfurization lean solution entering from the top of the natural gas absorption tower, dehydrating the gas discharged from the tower, and then entering a natural gas pipeline of a product for conveying; the rich liquid at the bottom of the natural gas absorption tower enters the top of a regeneration tower after passing through a flash evaporation tower and a lean-rich liquid heat exchanger, the high Wen Pinye at the bottom of the regeneration tower is pumped into the top of the absorption tower for recycling by a lean liquid pump after being cooled by the lean-rich liquid heat exchanger and a lean liquid cooler, and the acid gas generated by the regeneration tower enters a combustion furnace of a sulfur recovery unit after passing through an acid gas cooler and an acid gas separator;
2) The acid gas from the acid gas separator of the natural gas desulfurization unit enters a combustion furnace to be combusted to generate a Claus reaction, then enters a Claus reactor to further react, and hydrogen sulfide of more than 99% in the acid gas is converted into sulfur to obtain high Wen Yeliu, and enters a sulfur condenser to be cooled to obtain an industrial sulfur product, wherein the residual tail gas mainly contains nitrogen, carbon dioxide and a small amount of sulfide;
3) The tail gas from the Claus reactor of the sulfur recovery unit enters a tail gas hydrogenation reactor, sulfide in the tail gas is completely converted into hydrogen sulfide, then enters a tail gas quenching tower for cooling, then enters the bottom of a tail gas absorption tower for countercurrent contact with lean liquid entering from the top of the tail gas absorption tower, and the discharged gas mainly contains a small amount of carbon dioxide and trace hydrogen sulfide and then enters a tail gas incinerator for combustion and emission; the rich liquid at the bottom of the absorption tower is pumped into a lean-rich liquid heat exchanger through a rich liquid pump and then enters the top of a tail gas regeneration tower, the high Wen Pinye at the bottom of the tail gas regeneration tower is cooled by the lean-rich liquid heat exchanger and a lean liquid cooler and then enters the top of the tail gas absorption tower for recycling, and the sour gas flow with high carbon-sulfur ratio generated by the regeneration tower enters an sour gas concentration unit after passing through the sour gas cooler and the acid gas separator;
4) The regenerated acid gas flow with high carbon-sulfur ratio from the tail gas treatment unit enters the bottom of the acid gas absorption tower to be in countercurrent contact with lean liquid entering from the top of the acid gas absorption tower after being cooled, and the gas discharged from the tower is obtained into high-concentration carbon dioxide gas flow, enters the carbon dioxide pretreatment unit to be dehydrated and compressed, and decarburization and carbon capture are completed; the rich liquid at the bottom of the acid gas absorption tower enters the top of the regeneration tower after being pumped into the lean-rich liquid heat exchanger by the rich liquid pump, the high Wen Pinye at the bottom of the regeneration tower enters the top of the acid gas absorption tower for recycling after being cooled by the lean-rich liquid heat exchanger and the lean liquid cooler, and the acid gas generated by the regeneration tower returns to the inlet pipeline of the sulfur recovery unit combustion furnace after passing through the acid gas cooler and the acid gas separator for sulfur recovery.
The lean solution entering the tail gas absorption tower in the tail gas treatment unit is a full-stripping solvent, and comprises a primary amine type aqueous solution and a full-stripping formula solvent aqueous solution, wherein the molecules of the MEA (ethanolamine), DEA (diethanolamine) and the like at least contain one-NH 2 or-NH-; the lean solution entering the acid gas absorption tower in the acid gas concentration unit is a selective absorption solvent, and comprises MDEA (methyldiethanolamine) or tertiary amine without hydrogen atoms on amino, hindered amine and a formula solvent aqueous solution with selective removal of hydrogen sulfide.
According to the decarbonization system and process, the absorption tower in the existing tail gas treatment unit is reformed or newly built, the absorption tower is reformed or newly built into the plate tower with the tower plate number larger than 20 layers, meanwhile, the absorption process of the absorption tower is improved, most of carbon dioxide and a small amount of hydrogen sulfide in sulfur recovery tail gas are removed by adopting a full-stripping solvent, the low-flow high-carbon sulfur-ratio sour gas is obtained through regeneration, and then the sour gas is selectively absorbed by utilizing an additionally-added acid gas concentration unit to obtain high-concentration carbon dioxide gas flow, so that decarbonization and carbon capture are completed.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. according to the flue gas decarbonization system and the flue gas decarbonization process for purifying natural gas, provided by the embodiment of the invention, an original tail gas treatment unit is utilized, most of carbon dioxide and a small amount of hydrogen sulfide in sulfur recovery tail gas are removed by adopting a full-stripping solvent after an absorption tower is modified, a low-flow high-carbon-sulfur ratio sour gas is obtained through regeneration, and then a high-concentration carbon dioxide gas flow is obtained after the sour gas is selectively absorbed by an acid gas concentration device, so that decarbonization treatment and high-efficiency carbon capture are completed;
2. according to the flue gas decarbonization system and the flue gas decarbonization process for purifying the natural gas, a set of large-scale alcohol amine decarbonization device is not required to be newly built, and only a set of small acid gas concentration unit is required to be built and combined with the tail gas treatment unit for purifying the natural gas, so that carbon trapping of tail gas of an existing natural gas purification plant can be met;
3. the flue gas decarbonization system and the flue gas decarbonization process for purifying the natural gas provided by the embodiment of the invention have the advantages that the newly added acid gas concentration unit occupies small area, the process is simple, and the flue gas carbon capture construction investment can be greatly reduced.
Drawings
In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings that are needed in the examples will be briefly described below, it being understood that the following drawings only illustrate some examples of the present invention and therefore should not be considered as limiting the scope, and that other related drawings may be obtained from these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flow chart of a flue gas decarbonization process for purifying natural gas provided in embodiment 1 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent, and the description thereof is merely illustrative of the present invention and not intended to be limiting.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: no such specific details are necessary to practice the invention. In other instances, well-known materials or methods have not been described in detail in order to avoid obscuring the present invention.
Throughout the specification, references to "one embodiment," "an embodiment," "one example," or "an example" mean: a particular feature, structure, or characteristic described in connection with the embodiment or example is included within at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment," "in an example," or "in an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
In the description of the present invention, the terms "front," "back," "left," "right," "upper," "lower," "vertical," "horizontal," "high," "low," "inner," "outer," and the like indicate or imply a particular orientation of the device or element to be referred to, but are not intended to limit the scope of the invention.
Example 1
The decarbonization process for purifying natural gas provided by the embodiment of the invention is shown in fig. 1, and comprises the following specific steps:
1) Introducing natural gas from the bottom of a natural gas absorption tower, carrying out countercurrent contact with desulfurization lean solution entering from the top of the natural gas absorption tower, dehydrating the gas discharged from the tower, and then entering a natural gas pipeline of a product for conveying; the rich liquid at the bottom of the natural gas absorption tower enters the top of a regeneration tower after passing through a flash evaporation tower and a lean-rich liquid heat exchanger, the high Wen Pinye at the bottom of the regeneration tower is pumped into the top of the absorption tower for recycling by a lean liquid pump after being cooled by the lean-rich liquid heat exchanger and a lean liquid cooler, and the acid gas generated by the regeneration tower enters a combustion furnace of a sulfur recovery unit after passing through an acid gas cooler and an acid gas separator;
2) The acid gas from the acid gas separator of the natural gas desulfurization unit enters a combustion furnace to be combusted to generate a Claus reaction, then enters a Claus reactor to further react, and hydrogen sulfide of more than 99% in the acid gas is converted into sulfur to obtain high Wen Yeliu, and enters a sulfur condenser to be cooled to obtain an industrial sulfur product, wherein the residual tail gas mainly contains nitrogen, carbon dioxide and a small amount of sulfide;
3) The tail gas from the Claus reactor of the sulfur recovery unit enters a tail gas hydrogenation reactor, all sulfides in the tail gas are converted into hydrogen sulfide, then the hydrogen sulfide enters a tail gas quenching tower for cooling, then the hydrogen sulfide enters the bottom of a tail gas absorption tower to be in countercurrent contact with lean solution (MEA 30%) entering the top of the tail gas absorption tower, and the gas from the tower is completely dehydrated and mainly contains a small amount of carbon dioxide and trace hydrogen sulfide, and then the gas enters a tail gas incinerator for combustion emission; the rich liquid at the bottom of the absorption tower is pumped into a lean-rich liquid heat exchanger through a rich liquid pump and then enters the top of a tail gas regeneration tower, the high Wen Pinye at the bottom of the tail gas regeneration tower is cooled by the lean-rich liquid heat exchanger and a lean liquid cooler and then enters the top of the tail gas absorption tower for recycling, and the regenerated acid gas 1 with high carbon-sulfur ratio generated by the regeneration tower enters an acid gas concentration unit after passing through an acid gas cooler and an acid gas separator;
4) The regenerated acid gas 1 with high carbon-sulfur ratio from the tail gas treatment unit enters the bottom of the acid gas absorption tower after being cooled and is in countercurrent contact with lean solution (45% MDEA) entering the top of the acid gas absorption tower, the tail gas is concentrated by the gas from the tower to form a high-concentration carbon dioxide gas flow, and the high-concentration carbon dioxide gas flow enters the carbon dioxide pretreatment unit for dehydration and compression to finish decarburization and carbon capture; the rich liquid at the bottom of the acid gas absorption tower enters the top of the regeneration tower after being pumped into the lean-rich liquid heat exchanger by the rich liquid pump, the high Wen Pinye at the bottom of the regeneration tower enters the top of the acid gas absorption tower for recycling after being cooled by the lean-rich liquid heat exchanger and the lean liquid cooler, and the regenerated acid gas 2 generated by the regeneration tower returns to the inlet pipeline of the combustion furnace of the sulfur recovery unit after passing through the acid gas cooler and the acid gas separator for sulfur recovery.
Example 2
The conventional tail gas treatment device SOCT desulfurization + tail gas carbon capture route is as follows:
1) The same process of natural gas desulfurization and sulfur recovery as in the embodiment are adopted to obtain tail gas, and then a tail gas treatment device SOCT is adopted to carry out desulfurization to obtain desulfurized tail gas;
2) And introducing the desulfurization tail gas into an alcohol amine decarbonization device, discharging tower gas to obtain decarbonization tail gas, and regenerating rich liquid to obtain regenerated acid gas.
The process route of the invention provided in example 1 (step 3 and step 4 in example 1) and the conventional route of this example were used to desulphurize and decarbonize the tail gas with the same component content, the composition of the tail gas before entering the hydrogenation reactor was mainly H 2 S 2.22％、CO 2 26.73% of flow 12374Nm 3 And (h) entering a hydrogenation reactor and carrying out desulfurization and decarbonization on specific parametersAs shown in table 1 below.
TABLE 1 values of gas parameters at various stages in the tail gas treatment process
Example 3
The conventional tail gas treatment device SOCT desulfurization + tail gas carbon capture route is as follows:
1) The same process of natural gas desulfurization and sulfur recovery as in the embodiment are adopted to obtain tail gas, and then a tail gas treatment device SOCT is adopted to carry out desulfurization to obtain desulfurized tail gas;
2) Introducing the desulfurization tail gas into an alcohol amine decarbonization device, discharging tower gas to obtain decarbonization tail gas, and regenerating rich liquid to obtain regenerated acid gas which is high-concentration carbon dioxide gas flow.
The process route of the invention provided in example 1 (step 3 and step 4 in example 1) and the conventional route of this example were used to desulphurize and decarbonize the tail gas with the same component content, the composition of the tail gas before entering the hydrogenation reactor was mainly H 2 S 1.03％、CO 2 32.23%, flow 12403Nm 3 And/h, specific parameters after entering the hydrogenation reactor and carrying out desulfurization and decarbonization are shown in the following table 1.
TABLE 2 values of gas parameters at various stages in the tail gas treatment process
As can be seen from the data in tables 1 and 2, in order to obtain higher CO, the conventional SCOT desulfurization+amine decarburization process is adopted 2 The recycling rate and the recycling quantity of the decarbonization solution need to reach 100m 3 Above/h, the energy consumption and investment of the device are very large, and by adopting the process route of the invention, only the absorption tower in the SCOT process is slightly changedMaking and replacing the mixture into a full-stripping solvent, and concentrating the acid gas to indirectly obtain low-flow high-concentration CO 2 The circulation amount of the solution during concentration is only 30m 3 About/h, the treated acid gas amount is only 34% of the original decarbonizing tail gas amount, so that the construction investment and the operation cost of the device can be greatly reduced.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The flue gas decarburization system for purifying the natural gas is characterized by comprising a natural gas desulfurization unit, a sulfur recovery unit, a tail gas treatment unit and an acid gas concentration unit which are connected in sequence;
the natural gas desulfurization unit comprises a natural gas absorption tower, a flash evaporation tower and a regeneration tower;
the sulfur recovery unit comprises a combustion furnace and a Claus reactor;
the tail gas treatment unit comprises a tail gas hydrogenation reactor, a quenching tower, a tail gas absorption tower, a tail gas regeneration tower and a tail gas incinerator;
the acid gas concentration unit comprises an acid gas absorption tower and an acid gas regeneration tower;
in the tail gas treatment unit, a tail gas absorption tower removes carbon dioxide and a small amount of sulfides in the tail gas by using a full-stripping solvent, and then the tail gas is introduced into a tail gas regeneration tower rich liquor for regeneration to obtain a high carbon-sulfur ratio acid gas flow;
in the acid gas concentration unit, the acid gas absorption tower removes hydrogen sulfide in the high carbon-sulfur ratio acid gas flow by utilizing the selective absorption type desulfurization solvent to obtain a high-concentration carbon dioxide gas flow.
2. The flue gas decarbonizing system for natural gas purification according to claim 1, wherein the natural gas desulfurization unit further comprises a purification gas separator, an acid gas separator, a lean-rich liquid heat exchanger, a lean liquid cooler, an acid gas air cooler, and a lean liquid pump.
3. The flue gas decarbonizing system for natural gas purification according to claim 1, wherein the tail gas treatment unit further comprises a purification gas separator, an acid gas separator, a lean-rich liquid heat exchanger, a lean liquid cooler, an acid gas air cooler, a lean liquid pump, and a rich liquid pump.
4. A flue gas decarbonizing system for natural gas purification according to claim 1, wherein the acid gas concentrating unit comprises a lean-rich liquid heat exchanger, a reboiler, an acid gas cooler, a lean liquid pump, a rich liquid pump.
5. The flue gas decarbonization system for purifying natural gas according to claim 1, wherein the total stripping solvent is MEA (ethanolamine), DEA (diethanolamine) or an aqueous solution of primary secondary amine type or total stripping formulation solvent containing at least one-NH 2 or-NH-in the molecule.
6. A flue gas decarbonizing system for purifying natural gas according to claim 1, wherein the selective absorption type desulfurization solvent is MDEA (methyldiethanolamine), tertiary amine or hindered amine having no hydrogen atom on the amino group, or formulated solvent aqueous solution having selective removal of hydrogen sulfide.
7. A flue gas decarbonizing system for natural gas purification according to claim 1, wherein the gas outlet line of the final stage claus reactor of the sulfur recovery unit is connected to the inlet line of the tail gas hydrogenation reactor in the tail gas treatment unit; an acid gas outlet pipeline of the tail gas regeneration tower of the tail gas treatment unit is connected with a gas inlet pipeline of an acid gas absorption tower in the acid gas concentration unit; the gas outlet pipeline of the acid gas regeneration tower of the acid gas concentration unit is connected with the inlet pipeline of the combustion furnace of the sulfur recovery unit.
8. A flue gas decarbonizing system for purifying natural gas according to claim 3, wherein the natural gas desulfurization unit adopts an alcohol amine process or a derivative process thereof for desulfurization and decarbonizing.
9. A flue gas decarbonizing system for purifying natural gas according to claim 3, wherein the tail gas treatment unit adopts a SCOT hydrogenation reduction absorption process or a derivative process thereof and an alcohol amine process or a derivative process thereof for desulfurization and decarbonization.
10. A flue gas decarbonization process for natural gas purification, comprising the steps of:
1) Desulfurizing and decarbonizing natural gas: introducing natural gas into a natural gas desulfurization unit, absorbing hydrogen sulfide and carbon dioxide acid gas in the natural gas by utilizing a desulfurization solution, and then enriching the solution in a regeneration tower and heating to release the absorbed acid gas;
2) And (3) sulfur recovery: introducing the acid gas in the step 1) into a sulfur recovery unit, converting more than 99% of hydrogen sulfide in the acid gas into product sulfur through a Claus reaction, and remaining tail gas containing nitrogen, carbon dioxide and a small amount of sulfide;
3) Desulfurizing and decarbonizing tail gas: introducing the tail gas in the step 2) into a tail gas absorption tower, removing carbon dioxide and a small amount of sulfides in the tail gas by using a full-stripping solvent, and then regenerating rich liquid in a tail gas regeneration tower to obtain a high-carbon sulfur ratio acid gas flow;
4) Acid gas concentration: and (3) removing all hydrogen sulfide and a small part of carbon dioxide from the high-carbon sulfur ratio acid gas flow obtained in the step (3) in an acid gas concentration unit through a selective absorption desulfurization solvent in an acid gas absorption tower to obtain a high-concentration carbon dioxide gas flow, and completing the decarbonization of the natural gas purified flue gas.
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