CN117432492A - SCV flue gas carbon capture power circulation system and process based on LNG cold energy - Google Patents
SCV flue gas carbon capture power circulation system and process based on LNG cold energy Download PDFInfo
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 249
- 239000003546 flue gas Substances 0.000 title claims abstract description 247
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 88
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 29
- 239000003949 liquefied natural gas Substances 0.000 claims abstract description 74
- 238000010248 power generation Methods 0.000 claims abstract description 43
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 36
- 238000002309 gasification Methods 0.000 claims abstract description 33
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 18
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 18
- 238000000926 separation method Methods 0.000 claims abstract description 15
- 230000008016 vaporization Effects 0.000 claims abstract description 15
- 239000007789 gas Substances 0.000 claims abstract description 11
- 239000006200 vaporizer Substances 0.000 claims abstract description 11
- 238000009833 condensation Methods 0.000 claims abstract description 9
- 230000005494 condensation Effects 0.000 claims abstract description 9
- 238000007906 compression Methods 0.000 claims abstract description 7
- 230000006835 compression Effects 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 230000018044 dehydration Effects 0.000 claims abstract description 7
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 7
- 239000002912 waste gas Substances 0.000 claims abstract description 7
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 194
- 238000005261 decarburization Methods 0.000 claims description 41
- 239000002737 fuel gas Substances 0.000 claims description 23
- 239000007788 liquid Substances 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 17
- 239000003345 natural gas Substances 0.000 claims description 15
- 239000000779 smoke Substances 0.000 claims description 14
- 239000007791 liquid phase Substances 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 238000002485 combustion reaction Methods 0.000 claims description 12
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 8
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 8
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 claims description 8
- 239000012530 fluid Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 239000001282 iso-butane Substances 0.000 claims description 4
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 claims description 4
- 239000001294 propane Substances 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 125000004122 cyclic group Chemical group 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 claims description 2
- 230000008020 evaporation Effects 0.000 claims description 2
- 239000001301 oxygen Substances 0.000 claims description 2
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- 229920006395 saturated elastomer Polymers 0.000 claims description 2
- 238000005191 phase separation Methods 0.000 claims 1
- 238000009834 vaporization Methods 0.000 abstract description 7
- 238000005265 energy consumption Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 239000013535 sea water Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- QUWBSOKSBWAQER-UHFFFAOYSA-N [C].O=C=O Chemical compound [C].O=C=O QUWBSOKSBWAQER-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
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- 238000005262 decarbonization Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
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Abstract
The invention belongs to the fields of liquefied natural gas cold energy utilization and carbon dioxide capture, and particularly discloses an SCV flue gas carbon capture power circulation system and process based on LNG cold energy. For low carbon operation of an LNG receiving or LNG vaporization station containing an SCV vaporizer. The system comprises an LNG gasification unit, an SCV flue gas carbon capture unit, an LNG cold energy power cycle unit and an exhaust gas expansion power generation unit. In the SCV flue gas carbon capture unit, the flue gas is subjected to the technical processes of dehydration, cooling, primary compression, cooling, secondary compression, precooling, condensation and separation in sequence. In the LNG cold energy power cycle unit, the mixed working medium passes through the organic Rankine cycle process of two-stage expansion. In the waste gas expansion power generation unit, decarbonized flue gas passes through a two-stage direct expansion power generation process. According to the invention, the carbon emission of LNG gasification links by using the SCV gasifier is reduced, and the LNG cold energy utilization rate is improved.
Description
Technical Field
The invention belongs to the fields of liquefied natural gas cold energy utilization and carbon dioxide capture, and particularly relates to an SCV flue gas carbon capture power circulation system and process based on LNG cold energy.
Background
Carbon Capture and sequestration (Utilization and Storage, CCUS) technology is an important technology, wherein Carbon Capture is an important technical unit in CCUS technology, and Carbon dioxide Capture technologies include absorption, adsorption, membrane separation, cryogenic separation, etc., and cryogenic separation is to make use of differences in physical properties of components in feed gas, which is subjected to multiple compression and refrigeration to CO 2 Phase change occurs to become liquid, and carbon trapping is realized. The low-temperature separation method has the defects that refrigeration generates high energy consumption, but can utilize LNG cold energy to carry out low-temperature capture of carbon dioxide in an LNG receiving station.
LNG (Liquified Natural Gas) is liquefied natural gas, is low-temperature liquid at-162 ℃, contains huge cold energy resources, and has the theoretically available cold energy of 240 kW.h after heat exchange gasification of one ton of LNG. In LNG receiving and LNG vaporization stations, LNG vaporization mainly uses an open rack seawater vaporizer (ORV), an intermediate medium vaporizer (IFV), an air-temperature vaporizer (AAV), and a Submerged Combustion Vaporizer (SCV) for vaporization operation of LNG. Wherein the ORV and the IFV both adopt sea water for LNG gasification, and the AAV adopts air for LNG gasification. Because AAV has a low LNG throughput and neither ORV nor IFV can be used properly when the seawater temperature is low in winter, it is necessary to run SCV for LNG vaporization. The SCV uses natural gas combustion to generate heat to heat softened water in the water bath, and is further used for heating and gasifying LNG. In actual production, the temperature of the flue gas generated by the SCV gasifier is about 25-65 ℃, and the flue gas is always directly discharged into the air, so that energy waste is caused, and carbon emission of an LNG receiving station and an LNG gasification station is increased.
Disclosure of Invention
The invention aims to provide an SCV flue gas carbon capture power circulation system based on LNG cold energy, which effectively solves the problem of carbon emission increase caused by direct discharge of flue gas when an SCV gasifier is used currently.
In order to solve the technical problems, the invention adopts the following technical scheme:
the utility model provides a SCV flue gas carbon entrapment power circulation system based on LNG cold energy, includes LNG gasification unit, SCV flue gas carbon entrapment unit, LNG cold energy power circulation unit and waste gas expansion power generation unit, and low pressure LNG or high pressure LNG from LNG receiving station or LNG gasification station divide into three LNG tributaries through the tee bend, and first LNG tributaries get into LNG gasification unit, and after the second LNG tributaries got into LNG cold energy power circulation unit, get into SCV flue gas carbon entrapment unit after mixing with the third LNG tributaries in the LNG blender.
The LNG vaporization unit includes an SCV vaporizer.
The SCV flue gas carbon capture unit comprises a flue gas dryer, an SCV flue gas channel of a first heat exchanger, an SCV flue gas channel of a first flue gas compressor, an SCV flue gas channel of a second heat exchanger, an SCV flue gas channel of a second flue gas compressor, an SCV flue gas channel of a third heat exchanger, an SCV flue gas channel of a fourth heat exchanger and a gas-liquid separator which are connected in sequence, wherein the flue gas dryer is connected with a flue gas outlet of an SCV gasifier; the LNG passageway of fourth heat exchanger connects the export of LNG blender, the LNG blender includes two inlets, connects the LNG passageway and the third strand LNG tributary of fifth heat exchanger respectively, the second strand LNG tributary is connected to the LNG passageway entry of fifth heat exchanger.
The LNG cold energy power cycle unit adopts mixed working medium multistage expansion organic Rankine cycle and comprises a mixed working medium channel of a fifth heat exchanger, a first mixed working medium pump, a mixed working medium channel of the first heat exchanger, a first expansion generator set, a mixed working medium channel of a second heat exchanger and a second expansion generator set which are in cyclic connection.
The waste gas expansion power generation unit comprises a decarburization flue gas channel of a third heat exchanger, a third expansion power generation unit, a first air temperature type heater, a fourth expansion power generation unit and a second air temperature type heater which are sequentially connected, wherein the decarburization flue gas channel of the third heat exchanger is connected with a decarburization flue gas outlet of the gas-liquid separator.
And heat transfer mediums in the two channels of the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger and the fifth heat exchanger flow reversely.
The invention further aims to provide an SCV flue gas carbon capture power cycle process based on LNG cold energy, which effectively solves the problem of carbon emission increase caused by direct discharge of flue gas when an SCV gasifier is used currently.
The SCV flue gas carbon capture power circulation process based on LNG cold energy comprises the following processes based on the SCV flue gas carbon capture power circulation system described in the embodiment.
The low-pressure LNG or high-pressure LNG from the LNG receiving station or the LNG gasification station is divided into three LNG branches through a tee joint, the first LNG branch enters the LNG gasification unit, the second LNG branch enters the LNG cold energy power circulation unit and then enters the SCV flue gas carbon capture unit after being mixed with the third LNG branch in the LNG mixer.
(1) LNG gasification unit: the first LNG tributary enters the SCV vaporizer to be vaporized, and fuel gas from the LNG receiving station or the LNG vaporizing station enters the SCV vaporizer to be combusted to heat and vaporize the LNG.
Air from the external environment is pressurized to micro positive pressure, then enters an SCV gasifier to participate in combustion of fuel gas, LNG is gasified into natural gas, finally, the natural gas is conveyed to a user through a natural gas output pipeline, and the natural gas is suitable to enter a downstream output pipeline network at 15-25 ℃; flue gas generated by combustion of fuel gas in the SCV gasifier enters the SCV flue gas carbon capture unit.
(2) SCV flue gas carbon capture unit: the flue gas from the SCV gasifier firstly enters a flue gas dryer for dehydration, then enters an SCV flue gas channel of a first heat exchanger for heat exchange with mixed working medium in a mixed working medium channel of the first heat exchanger, the flue gas is cooled to-100 ℃ to-90 ℃, then enters a first flue gas compressor for pressurization to 310kPa, then enters an SCV flue gas channel of a second heat exchanger for heat exchange with mixed working medium in a mixed working medium channel of the second heat exchanger, the flue gas is cooled to-40 ℃ to-30 ℃, then enters a second flue gas compressor for pressurization to 930kPa, the secondarily pressurized flue gas enters an SCV flue gas channel of a third heat exchanger for heat exchange with decarburized flue gas in a decarburized flue gas channel of the third heat exchanger, the flue gas is cooled to-100 ℃ to-90 ℃, then enters an SCV flue gas channel of a fourth heat exchanger for heat exchange with LNG (liquefied natural gas) from an LNG (LNG) mixer, the flue gas is cooled to-135 ℃ to-130 ℃, partial liquefaction or condensation of carbon dioxide in the carbon dioxide is realized, finally enters a gas-liquid phase carbon dioxide separator for carbon-liquid separation, and the flue gas is separated into a carbon-liquid phase carbon-carbon dioxide separation and the flue gas is separated, and the flue gas is discharged into a flue gas and the flue gas is expanded.
(3) Exhaust gas expansion power generation unit: the low-temperature high-pressure decarburization flue gas from the SCV flue gas carbon capture unit firstly enters a decarburization flue gas channel of a third heat exchanger to exchange heat with flue gas in the SCV flue gas channel of the third heat exchanger, the decarburization flue gas is heated to 60-80 ℃, then enters a third expansion generating set to carry out expansion power generation, the decarburization flue gas is expanded to 310kPa, then enters a first air temperature type heater to carry out heating, the decarburization flue gas is heated to-5-0 ℃, then enters a fourth expansion generating set to carry out expansion power generation, the decarburization flue gas is expanded to atmospheric pressure, then enters a second air temperature type heater to carry out heating, and the decarburization flue gas is heated to not lower than 5 ℃ below the ambient temperature and finally is discharged into the atmosphere.
(4) LNG cold energy power cycle unit: the mixed working medium is cooled to-130 ℃ to-140 ℃ to be changed into liquid phase, then enters a first mixed working medium pump to be pressurized to 1300 kPa-1350 kPa, then enters the mixed working medium channel of the first heat exchanger to exchange heat with smoke in the SCV smoke channel of the first heat exchanger, the mixed working medium is heated to-20 ℃ to-15 ℃ (ensuring that no liquid phase is separated out after the mixed working medium is expanded), then enters the first expansion generator set to perform expansion power generation, the mixed working medium is expanded to 460kPa, then enters the mixed working medium channel of the second heat exchanger to exchange heat with smoke in the SCV smoke channel of the second heat exchanger, the mixed working medium is heated to-30 ℃ to-25 ℃, and finally enters the second expansion generator set to perform expansion power generation, and the mixed working medium is expanded to 150kPa to complete the cycle.
Further, the main components of the low-pressure LNG, the high-pressure LNG or the fuel gas from the LNG receiving station or the LNG gasifying station comprise methane, ethane, propane, isobutane, n-butane and nitrogen, the pressure of the low-pressure LNG is 6.0-7.0 MPa, the pressure of the high-pressure LNG is 10.0-11.0 MPa, the temperatures of the low-pressure LNG and the high-pressure LNG are 140 ℃ below zero to 155 ℃ below zero, the pressure of the fuel gas is 0.5-0.6 MPa, and the temperature of the fuel gas is 10-20 ℃.
Further, in the LNG gasification unit, the temperature of the air is less than 5 ℃, the air is pressurized to 116.15kPa by a blower, the main components of the flue gas comprise nitrogen, saturated steam, carbon dioxide and oxygen, the pressure of the flue gas is 116.15kPa, and the temperature of the flue gas is 25-65 ℃.
Further, in the SCV flue gas carbon capture unit, the flue gas is subjected to the technical processes of dehydration, cooling, primary compression, cooling, secondary compression, precooling, condensation and separation in sequence.
Further, in the LNG cold energy power cycle unit, the mixed working medium is subjected to a two-stage expansion organic Rankine cycle process of condensation, pressurization, evaporation, one-stage expansion, heating, two-stage expansion and condensation, and the components of the mixed working medium are methane and ethane, wherein the molar content of the methane is 20%, and the molar content of the ethane is 80%.
Further, in the exhaust gas expansion power generation unit, the decarbonized flue gas is subjected to a process flow of two-stage direct expansion power generation by heating, primary expansion, heating, secondary expansion and heating discharge in sequence.
The beneficial technical effects of the invention are as follows:
(1) The invention integrates LNG gasification, LNG cold energy power generation, SCV gasifier flue gas carbon capture and waste gas direct expansion power generation, fully utilizes LNG cold energy, SCV flue gas heat energy and waste gas (i.e. decarbonized flue gas) pressure energy, reduces system energy consumption and improves the systemAnd the efficiency is improved, carbon capture is realized, and carbon emission in the LNG gasification process is reduced.
(2) The invention greatly reduces the energy consumption of the flue gas carbon capture ring, reduces the carbon emission in the LNG gasification link by using the SCV gasifier, and improves the LNG cold energy utilization rate. The invention is suitable for the LNG receiving station or the LNG vaporizing station with the SCV vaporizer, and is beneficial to realizing the low-carbon operation of the LNG receiving station or the LNG vaporizing station.
Drawings
Fig. 1 is a schematic diagram of the system connection structure of the present invention.
In the figure: t-1-tee; SCV-1-submerged combustion gasifier (SCV); b-1-a blower; d-1, a flue gas dryer; h-1, a first heat exchanger; h-2-a second heat exchanger; h-3-a third heat exchanger; h-4-fourth heat exchanger; h-5-a fifth heat exchanger; c-1, a first flue gas compressor; c-2, a second flue gas compressor; p-1, a first mixed working medium pump; e-1, a first expansion generating set; e-2-a second expansion generating set; e-3-a third expansion generating set; e-4-a fourth expansion generating set; M-1-LNG mixer; s-1, a gas-liquid separator; a-1 is a first air temperature type heater; a-2-a second air temperature type heater;
in the figure: l1 to L6 are LNG streams; R1-R6 are mixed working medium material flows; f1 to F8 are flue gas streams; E1-E6 are decarbonized flue gas streams; NG is an export natural gas stream; air is an Air stream; fuel is a Fuel gas stream; water is a flue gas de-watering stream; c is a liquid carbon dioxide stream.
Detailed Description
Example 1: as shown in fig. 1, an SCV flue gas carbon capture power cycle system based on LNG cold energy includes the following equipment: the system comprises a tee T-1, an SCV gasifier SCV-1, a blower B-1, a flue gas dryer D-1, a first heat exchanger H-1, a second heat exchanger H-2, a third heat exchanger H-3, a fourth heat exchanger H-4, a fifth heat exchanger H-5, a first flue gas compressor C-1, a second flue gas compressor C-2, a gas-liquid separator S-1, a first mixed working medium pump P-1, a first expansion generator set E-1, a second expansion generator set E-2, a third expansion generator set E-3, a fourth expansion generator set E-4, a first air temperature type heater A-1, a second air temperature type heater A-2 and an LNG mixer M-1.
The heat transfer mediums in the two channels of the first heat exchanger H-1, the second heat exchanger H-2, the third heat exchanger H-3, the fourth heat exchanger H-4 and the fifth heat exchanger H-5 flow reversely.
The SCV flue gas carbon capture power circulation system based on LNG cold energy comprises an LNG gasification unit, an SCV flue gas carbon capture unit, an LNG cold energy power circulation unit and an exhaust gas expansion power generation unit, wherein low-pressure LNG or high-pressure LNG from an LNG receiving station or an LNG gasification station is divided into three LNG branches through a tee T-1, a first LNG branch L1 enters the LNG gasification unit, a second LNG branch L2 enters the LNG cold energy power circulation unit and then enters the SCV flue gas carbon capture unit after being mixed with a third LNG branch L3 in an LNG mixer M-1.
The LNG vaporization unit includes an SCV vaporizer SCV-1.
The SCV flue gas carbon capture unit comprises a flue gas dryer D-1, an SCV flue gas channel 1 of a first heat exchanger H-1, a first flue gas compressor C-1, an SCV flue gas channel 2 of a second heat exchanger H-2, a second flue gas compressor C-2, an SCV flue gas channel 3 of a third heat exchanger H-3, an SCV flue gas channel 4 of a fourth heat exchanger H-4 and a gas-liquid separator S-1 which are sequentially connected, wherein the flue gas dryer D-1 is connected with a flue gas outlet of an SCV gasifier SCV-1. The LNG channel 5 of the fourth heat exchanger H-4 is connected with the outlet of the LNG mixer M-1, the LNG mixer M-1 comprises two inlets, the LNG channel 6 and the third LNG tributary L3 of the fifth heat exchanger H-5 are respectively connected, and the inlet of the LNG channel 6 of the fifth heat exchanger H-5 is connected with the second LNG tributary L2.
The LNG cold energy power cycle unit adopts mixed working medium multistage expansion organic Rankine cycle and comprises a mixed working medium channel 7 of a fifth heat exchanger H-5, a first mixed working medium pump P-1, a mixed working medium channel 8 of the first heat exchanger H-1, a first expansion generator set E-1, a mixed working medium channel 9 of a second heat exchanger H-2 and a second expansion generator set E-2 which are in cyclic connection.
The waste gas expansion power generation unit comprises a decarburization flue gas channel 10 of a third heat exchanger H-3, a third expansion power generation unit E-3, a first air temperature type heater A-1, a fourth expansion power generation unit E-4 and a second air temperature type heater A-2 which are sequentially connected, wherein the decarburization flue gas channel 10 of the third heat exchanger H-3 is connected with a decarburization flue gas outlet of a gas-liquid separator S-1.
Example 2: as shown in fig. 1, an SCV flue gas carbon capture power cycle process based on LNG cold energy is based on the SCV flue gas carbon capture power cycle system described in example 1. The pressure of the high-pressure LNG from the LNG receiving station or the LNG vaporizing station is 10.1MPa, the temperature is-152.3 ℃, and the main components and the molar contents of the components of the high-pressure LNG are as follows: methane 90.8%, ethane 4.95%, propane 2.47%, isobutane 0.99%, n-butane 0.1% and nitrogen 0.61%.
The isentropic efficiency of the first flue gas compressor C-1, the second flue gas compressor C-2 and the blower B-1 is 85%, and the adiabatic efficiency of the first expansion generating set E-1, the second expansion generating set E-2, the third expansion generating set E-3, the fourth expansion generating set E-4 and the first mixed working medium pump P-1 is 80%. The method comprises the following technical processes:
(1) LNG gasification unit: after the high-pressure LNG (flow 294.1 t/h) is split by a tee joint, a first LNG tributary L1 (196.1 t/h) enters an SCV gasifier SCV-1 for gasification, fuel gas from an LNG receiving station or an LNG gasification station enters the SCV gasifier SCV-1 for combustion to heat and gasify the LNG, the pressure of the fuel gas is 601kPa, the temperature is 15 ℃, and the molar contents of main components and all components of the fuel gas are the same as the molar contents of the main components and all components of the high-pressure LNG. Air (101.3 kPa) at a temperature of 1 c from the external environment is pressurized to a micro positive pressure (116.15 kPa) by a blower B-1 before entering an SCV gasifier SCV-1 to participate in the combustion of fuel gas to gasify LNG into natural gas.
The gasified natural gas NG (24.09 ℃,9900 kPa) is conveyed to a user through a natural gas pipe network, the pressure of smoke generated by burning fuel gas in an SCV gasifier SCV-1 is 116.15kPa, the temperature is 26.36 ℃, and the smoke enters an SCV smoke carbon capture unit.
(2) SCV flue gas carbon capture unit: the flue gas (56296.3 kg/H) from the SCV gasifier SCV-1 firstly enters a flue gas dryer D-1 for dehydration, the dehydrated flue gas (55283.8 kg/H) enters a SCV flue gas channel 1 of the first heat exchanger H-1 for heat exchange with mixed working medium condensed and pressurized in an LNG cold energy power circulation unit in a mixed working medium channel 8 of the first heat exchanger H-1, the flue gas is cooled to-97.15 ℃, then enters a first flue gas compressor C-1 for pressurization to 310kPa, then enters a SCV flue gas channel 2 of the second heat exchanger H-2 for heat exchange with mixed working medium expanded in an LNG cold energy power circulation unit in a mixed working medium channel 9 of the second heat exchanger H-2, the flue gas is cooled to-36.19 ℃, then enters a second flue gas compressor C-2 for pressurization to 930kPa, the secondarily pressurized flue gas enters a SCV flue gas channel 3 of the third heat exchanger H-3 for decarbonization in a decarburization channel 10 of the third heat exchanger H-3, the flue gas enters a carbon dioxide liquid phase C-96 for heat exchange with a carbon dioxide liquid in a flue gas-4, and finally enters a carbon dioxide liquid phase C-4 to-4 for separation in the flue gas, and finally enters a carbon dioxide liquid-4 to realize the separation of the flue gas and the liquid phase-4 to realize the separation of the flue gas.
(3) Exhaust gas expansion power generation unit: the low-temperature high-pressure decarburization flue gas (-130 ℃,930kPa,48236.2 kg/H) from the SCV flue gas carbon capture unit firstly enters the decarburization flue gas channel 10 of the third heat exchanger H-3 to exchange heat with the flue gas secondarily pressurized in the SCV flue gas carbon capture unit in the SCV flue gas channel 3 of the third heat exchanger H-3, the decarburization flue gas is heated to 66.36 ℃ after the heat exchange, then enters the third expansion generator set E-3 to perform expansion power generation, the decarburization flue gas is expanded to 310kPa, then enters the first air temperature type heater A-1 to perform heating, the decarburization flue gas is heated to 0 ℃, then enters the fourth expansion generator set E-4 to perform expansion power generation, the decarburization flue gas is expanded to 101.3kPa, then enters the second air temperature type heater A-2 to perform heating, and the decarburization flue gas is heated to not lower than 5 ℃ below the ambient temperature and finally discharged into the atmosphere.
(4) LNG cold energy power cycle unit: the mixed working medium is cooled to-133.25 ℃ to become a liquid phase, then enters a first mixed working medium pump P-1 to be pressurized to 1300kPa, then enters a mixed working medium channel 8 of the first heat exchanger H-1 to exchange heat with flue gas dehydrated in an SCV flue gas carbon capture unit in the SCV flue gas channel 1 of the first heat exchanger H-1, the mixed working medium is heated to-15.89 ℃, then enters the first expansion power generator set E-1 to conduct expansion power generation, the mixed working medium is cooled to 460kPa, then enters the mixed working medium channel 9 of the second heat exchanger H-2 to be in contact with the SCV flue gas 2 of the second heat exchanger H-2 to conduct expansion power generation, then enters the mixed working medium channel 8 of the first heat exchanger H-1 to conduct heat exchange with flue gas dehydrated in the SCV flue gas carbon capture unit of the first heat exchanger H-1, and finally enters the mixed working medium to conduct expansion power generation after the mixed working medium is heated to the SCV flue gas carbon capture unit of the first heat in the SCV flue gas carbon capture unit of the first heat exchanger H-1, and finally enters the mixed working medium to conduct expansion power generation unit to conduct expansion power generation after the mixed working medium is heated to the SCV carbon capture unit of the SCV carbon and the SCV carbon.
In the embodiment, the energy consumption of the system is 688.2kW, the carbon capture amount of the system is 6959.2kg/h, the carbon capture rate is 95.63%, and the systemThe efficiency is 37.34%, and the LNG cold of the system is +.>The utilization rate is 62.75%.
Example 3: as shown in fig. 1, an SCV flue gas carbon capture power cycle process based on LNG cold energy is based on the SCV flue gas carbon capture power cycle system described in example 1. The pressure of the low-pressure LNG from the LNG receiving station or the LNG vaporizing station is 6.3MPa, the temperature is-155.0 ℃, and the low-pressure LNG comprises the following main components in molar content: methane 90.8%, ethane 4.95%, propane 2.47%, isobutane 0.99%, n-butane 0.1% and nitrogen 0.61%.
The isentropic efficiency of the first flue gas compressor C-1, the second flue gas compressor C-2 and the blower B-1 is 85%, and the adiabatic efficiency of the first expansion generating set E-1, the second expansion generating set E-2, the third expansion generating set E-3, the fourth expansion generating set E-4 and the first mixed working medium pump P-1 is 80%. The method comprises the following technical processes:
(1) LNG gasification unit: after the low-pressure LNG (flow 262.0 t/h) is split by a tee joint, a first LNG tributary L1 (178.5 t/h) enters an SCV gasifier SCV-1 for gasification, fuel gas from an LNG receiving station or an LNG gasification station enters the SCV gasifier SCV-1 for combustion to heat and gasify the LNG, the pressure of the fuel gas is 601kPa, the temperature is 15 ℃, and the molar contents of main components and all components of the fuel gas are the same as the molar contents of the main components and all components of the high-pressure LNG. Air (101.3 kPa) at a temperature of 1 c from the external environment is pressurized to a micro positive pressure (116.15 kPa) by a blower B-1 before entering an SCV gasifier SCV-1 to participate in the combustion of fuel gas to gasify LNG into natural gas.
The gasified natural gas NG (24.00 ℃,6100 kPa) is conveyed to a user through a natural gas pipe network, the pressure of smoke generated by burning fuel gas in an SCV gasifier SCV-1 is 116.15kPa, the temperature is 26.34 ℃, and the smoke enters an SCV smoke carbon capture unit.
(2) SCV flue gas carbon capture unit: the flue gas (55434.7 kg/H) from the SCV gasifier SCV-1 firstly enters a flue gas dryer D-1 for dehydration, the dehydrated flue gas (54438.4 kg/H) enters an SCV flue gas channel 1 of a first heat exchanger H-1 for heat exchange with mixed working fluid condensed and pressurized in an LNG cold energy power circulation unit in a mixed working fluid channel 8 of the first heat exchanger H-1, the flue gas is cooled to minus 96.55 ℃, then enters a first flue gas compressor C-1 for pressurization to 310kPa, then enters an SCV flue gas channel 2 of a second heat exchanger H-2 for heat exchange with mixed working fluid expanded in the LNG cold energy power circulation unit in a mixed working fluid channel 9 of the second heat exchanger H-2, the flue gas is cooled to minus 35.52 ℃, then enters a second flue gas compressor C-2 for pressurization to 930kPa, the flue gas after secondary pressurization enters an SCV flue gas channel 3 of a third heat exchanger H-3 to exchange heat with decarburization flue gas in a decarburization flue gas channel 10 of the third heat exchanger H-3, the flue gas is cooled to minus 96 ℃, then the SCV flue gas channel 4 entering a fourth heat exchanger H-4 exchanges heat with LNG (83.5 t/H,133.39 ℃) from an LNG mixer M-1 in an LNG channel 5 of the fourth heat exchanger H-4, the flue gas is cooled to minus 130 ℃, partial liquefaction of carbon dioxide in the flue gas is realized, finally, the flue gas enters a gas-liquid separator S-1 to realize gas-liquid separation, liquid phase in the flue gas is separated, carbon capture of the SCV flue gas is realized, and gas-phase decarburization flue gas after gas-liquid separation enters an exhaust gas expansion power generation unit.
(3) Exhaust gas expansion power generation unit: the low-temperature high-pressure decarburization flue gas (-130 ℃ and 930kPa,47449.9 kg/H) from the SCV flue gas carbon capture unit firstly enters a decarburization flue gas channel 10 of a third heat exchanger H-3 to exchange heat with the secondarily pressurized flue gas in the SCV flue gas carbon capture unit of the third heat exchanger H-3, the decarburization flue gas is heated to 67.74 ℃ after heat exchange, then enters a third expansion generator set E-3 to perform expansion power generation, the decarburization flue gas is expanded to 310kPa, then enters a first air temperature type heater A-1 to perform heating, the decarburization flue gas is heated to 0 ℃, then enters a fourth expansion generator set E-4 to perform expansion power generation, the decarburization flue gas is expanded to atmospheric pressure, then enters a second air temperature type heater A-2 to perform heating, and the decarburization flue gas is heated to not lower than 5 ℃ below the ambient temperature and finally is discharged into the atmosphere.
(4) LNG cold energy power cycle unit: the mixed working medium is cooled to-133.25 ℃ to become a liquid phase, then enters a first mixed working medium pump P-1 to be pressurized to 1300kPa, then enters a mixed working medium channel 8 of the first heat exchanger H-1 to exchange heat with flue gas dehydrated in an SCV flue gas carbon capture unit in the SCV flue gas channel 1 of the first heat exchanger H-1, the mixed working medium is heated to-15.89 ℃, then enters the first expansion generator set E-1 to be expanded to generate electricity, then enters a mixed working medium channel 9 of the second heat exchanger H-2 to be cooled to 460kPa to become a liquid phase, then enters a mixed working medium channel 9 of the second heat exchanger H-2 to be pressurized to 1300kPa, then enters a mixed working medium channel 8 of the first heat exchanger H-1 to exchange heat with flue gas dehydrated in an SCV flue gas carbon capture unit in the SCV flue gas carbon capture unit, and finally enters the mixed working medium to be heated to the SCV flue gas carbon capture unit of the first heat in the SCV flue gas carbon capture unit of the first heat exchanger H-1 to be heated to the second heat to the SCV carbon capture unit of the SCV carbon capture unit, and finally enters the SCV carbon capture unit to be heated to the SCV carbon capture unit of the SCV carbon.
In the embodiment, the energy consumption of the system is 684.9kW, the carbon capture amount of the system is 6851.9kg/h, the carbon capture rate is 95.63%, and the systemThe efficiency is 37.41%, and the LNG of the system is cold +.>The utilization rate is 63.06%.
It should be understood that the above description is not intended to limit the invention to the particular embodiments disclosed, but to limit the invention to the particular embodiments disclosed, and that the invention is not limited to the particular embodiments disclosed, but is intended to cover modifications, adaptations, additions and alternatives falling within the spirit and scope of the invention.
Claims (7)
1. The SCV flue gas carbon capture power circulation system based on LNG cold energy is characterized by comprising an LNG gasification unit, an SCV flue gas carbon capture unit, an LNG cold energy power circulation unit and an exhaust gas expansion power generation unit, wherein low-pressure LNG or high-pressure LNG from an LNG receiving station or an LNG gasification station is divided into three LNG branches through a tee joint, a first LNG branch enters the LNG gasification unit, a second LNG branch enters the LNG cold energy power circulation unit and then enters the SCV flue gas carbon capture unit after being mixed with a third LNG branch in an LNG mixer;
the LNG vaporizing unit comprises an SCV vaporizer;
the SCV flue gas carbon capture unit comprises a flue gas dryer, an SCV flue gas channel of a first heat exchanger, an SCV flue gas channel of a first flue gas compressor, an SCV flue gas channel of a second heat exchanger, an SCV flue gas channel of a second flue gas compressor, an SCV flue gas channel of a third heat exchanger, an SCV flue gas channel of a fourth heat exchanger and a gas-liquid separator which are connected in sequence, wherein the flue gas dryer is connected with a flue gas outlet of an SCV gasifier; the LNG channel of the fourth heat exchanger is connected with the outlet of the LNG mixer, the LNG mixer comprises two inlets, the LNG channel of the fifth heat exchanger and the third LNG tributary are respectively connected, and the LNG channel inlet of the fifth heat exchanger is connected with the second LNG tributary;
the LNG cold energy power cycle unit adopts mixed working medium multi-stage expansion organic Rankine cycle and comprises a mixed working medium channel of a fifth heat exchanger, a first mixed working medium pump, a mixed working medium channel of the first heat exchanger, a first expansion generator set, a mixed working medium channel of a second heat exchanger and a second expansion generator set which are in cyclic connection;
the waste gas expansion power generation unit comprises a decarburization flue gas channel of a third heat exchanger, a third expansion power generation unit, a first air temperature type heater, a fourth expansion power generation unit and a second air temperature type heater which are connected in sequence, wherein the decarburization flue gas channel of the third heat exchanger is connected with a decarburization flue gas outlet of a gas-liquid separator;
and heat transfer mediums in the two channels of the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger and the fifth heat exchanger flow reversely.
2. An SCV flue gas carbon capture power cycle process based on LNG cold energy, which is characterized by comprising the following processes based on the SCV flue gas carbon capture power cycle system of claim 1:
the low-pressure LNG or high-pressure LNG from the LNG receiving station or the LNG vaporizing station is divided into three LNG branches through a tee joint, the first LNG branch enters the LNG vaporizing unit, the second LNG branch enters the LNG cold energy power circulation unit and then is mixed with the third LNG branch in the LNG mixer, and then enters the SCV flue gas carbon capture unit;
b1, LNG gasification unit: the first LNG tributary enters an SCV gasifier for gasification, and fuel gas from an LNG receiving station or an LNG gasification station enters the SCV gasifier for combustion to heat and gasify LNG;
air from the external environment is pressurized to micro positive pressure, then enters an SCV gasifier to participate in combustion of fuel gas, LNG is gasified into natural gas, finally, the natural gas is conveyed to a user through a natural gas output pipeline, and flue gas generated by combustion of the fuel gas in the SCV gasifier enters an SCV flue gas carbon capture unit;
b2, SCV flue gas carbon capture unit: the flue gas from the SCV gasifier firstly enters a flue gas dryer for dehydration, then enters an SCV flue gas channel of a first heat exchanger for heat exchange with mixed working medium in a mixed working medium channel of the first heat exchanger, the flue gas is cooled to-100 ℃ to-90 ℃, then enters a first flue gas compressor for pressurization to 310kPa, then enters an SCV flue gas channel of a second heat exchanger for heat exchange with mixed working medium in a mixed working medium channel of the second heat exchanger, the flue gas is cooled to-40 ℃ to-30 ℃, then enters a second flue gas compressor for pressurization to 930kPa, the secondarily pressurized flue gas enters an SCV flue gas channel of a third heat exchanger for heat exchange with decarburized flue gas in a decarburized flue gas channel of the third heat exchanger, the flue gas is cooled to-100 ℃ to-90 ℃, then enters an SCV flue gas channel of a fourth heat exchanger for heat exchange with LNG (liquefied natural gas) from an LNG (LNG) mixer, the flue gas is cooled to-135 ℃ to-130 ℃, partial liquefaction or condensation of carbon dioxide in the carbon dioxide is realized, finally enters a gas-liquid phase carbon dioxide separator for carbon-liquid separation, and the flue gas is separated into a carbon-liquid phase carbon-liquid-separated and the flue gas is separated and then enters a flue gas-phase-separation unit for decarburized expansion;
b3, an exhaust gas expansion power generation unit: the low-temperature high-pressure decarburization flue gas from the SCV flue gas carbon capture unit firstly enters a decarburization flue gas channel of a third heat exchanger to exchange heat with flue gas in the SCV flue gas channel of the third heat exchanger, the decarburization flue gas is heated to 60-80 ℃, then enters a third expansion generating set to carry out expansion power generation, the decarburization flue gas is expanded to 310kPa, then enters a first air temperature type heater to carry out heating, the decarburization flue gas is heated to-5-0 ℃, then enters a fourth expansion generating set to carry out expansion power generation, the decarburization flue gas is expanded to atmospheric pressure, then enters a second air temperature type heater to carry out heating, and the decarburization flue gas is heated to not lower than 5 ℃ below the ambient temperature and finally is discharged into the atmosphere;
b4, LNG cold energy power cycle unit: the mixed working medium is cooled to-130 ℃ to-140 ℃ to be changed into liquid phase, then enters a first mixed working medium pump to be pressurized to 1300 kPa-1350 kPa, then enters the mixed working medium channel of the first heat exchanger to exchange heat with smoke in the SCV smoke channel of the first heat exchanger, the mixed working medium is heated to-20 ℃ to-15 ℃, then enters the first expansion power generator to perform expansion power generation, the mixed working medium is expanded to 460kPa, then enters the mixed working medium channel of the second heat exchanger to exchange heat with smoke in the SCV smoke channel of the second heat exchanger, and finally enters the second expansion power generator to perform expansion power generation, and the mixed working medium is expanded to 150kPa to complete circulation.
3. The LNG cold energy based SCV flue gas carbon capture power cycle process of claim 2, wherein the components of low-pressure LNG, high-pressure LNG or fuel gas from the LNG receiving station or LNG gasification station each include methane, ethane, propane, isobutane, n-butane and nitrogen, the pressure of the low-pressure LNG is 6.0MPa to 7.0MPa, the pressure of the high-pressure LNG is 10.0MPa to 11.0MPa, the temperature of each of the low-pressure LNG and the high-pressure LNG is-140 ℃ to-155 ℃, the pressure of the fuel gas is 0.5MPa to 0.6MPa, and the temperature of the fuel gas is 10 ℃ to 20 ℃.
4. An SCV flue gas carbon capture power cycle process based on LNG cold energy as claimed in claim 3 wherein in the LNG gasification unit the temperature of the air is less than 5 ℃, the air is pressurized by a blower to 116.15kPa, the components of the flue gas include nitrogen, saturated water vapour, carbon dioxide and oxygen, the pressure of the flue gas is 116.15kPa, the temperature of the flue gas is 25 ℃ to 65 ℃.
5. The LNG cold energy based SCV flue gas carbon capture power cycle process of claim 4, wherein in the SCV flue gas carbon capture unit, the flue gas is subjected to dehydration, cooling, primary compression, cooling, secondary compression, pre-cooling, condensation and separation processes sequentially.
6. The LNG cold energy based SCV flue gas carbon capture power cycle process of claim 5, wherein in the LNG cold energy power cycle unit, the mixed working fluid is subjected to a two-stage expansion organic rankine cycle process of condensation, pressurization, evaporation, primary expansion, heating, secondary expansion and condensation, and the components of the mixed working fluid are methane and ethane, wherein the molar content of methane is 20% and the molar content of ethane is 80%.
7. The LNG cold energy based SCV flue gas carbon capture power cycle process of claim 6, wherein in the exhaust gas expansion power generation unit, the decarbonized flue gas is subjected to a process flow of two-stage direct expansion power generation by heating, primary expansion, heating, secondary expansion, and heating discharge in sequence.
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