CN117869920A - Carbon dioxide collecting system of oxygen-enriched combustion boiler coupled with air separation device - Google Patents
Carbon dioxide collecting system of oxygen-enriched combustion boiler coupled with air separation device Download PDFInfo
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- CN117869920A CN117869920A CN202410037452.0A CN202410037452A CN117869920A CN 117869920 A CN117869920 A CN 117869920A CN 202410037452 A CN202410037452 A CN 202410037452A CN 117869920 A CN117869920 A CN 117869920A
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- inlet
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- flue gas
- carbon dioxide
- air separation
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 146
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 56
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 56
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 40
- 239000001301 oxygen Substances 0.000 title claims abstract description 40
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 40
- 238000000926 separation method Methods 0.000 title claims abstract description 32
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 17
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 99
- 239000003546 flue gas Substances 0.000 claims abstract description 99
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 36
- 235000011089 carbon dioxide Nutrition 0.000 claims abstract description 34
- 239000007788 liquid Substances 0.000 claims abstract description 25
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 11
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000002826 coolant Substances 0.000 claims description 28
- 238000000034 method Methods 0.000 claims description 15
- 239000007789 gas Substances 0.000 claims description 14
- 238000007906 compression Methods 0.000 claims description 13
- 239000000779 smoke Substances 0.000 claims description 6
- 230000006835 compression Effects 0.000 claims description 5
- 238000000605 extraction Methods 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims description 3
- 238000004064 recycling Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 abstract description 20
- 238000005265 energy consumption Methods 0.000 abstract description 11
- 230000008878 coupling Effects 0.000 abstract 1
- 238000010168 coupling process Methods 0.000 abstract 1
- 238000005859 coupling reaction Methods 0.000 abstract 1
- 238000001035 drying Methods 0.000 description 6
- 238000007789 sealing Methods 0.000 description 6
- 238000005057 refrigeration Methods 0.000 description 5
- 239000002918 waste heat Substances 0.000 description 5
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 description 4
- 239000012267 brine Substances 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 3
- 238000005086 pumping Methods 0.000 description 3
- 239000003507 refrigerant Substances 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 3
- 238000000859 sublimation Methods 0.000 description 3
- 230000008022 sublimation Effects 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000006477 desulfuration reaction Methods 0.000 description 2
- 230000023556 desulfurization Effects 0.000 description 2
- AFABGHUZZDYHJO-UHFFFAOYSA-N dimethyl butane Natural products CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000009972 noncorrosive effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/006—Layout of treatment plant
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04763—Start-up or control of the process; Details of the apparatus used
- F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
- F25J3/04975—Construction and layout of air fractionation equipments, e.g. valves, machines adapted for special use of the air fractionation unit, e.g. transportable devices by truck or small scale use
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Separation By Low-Temperature Treatments (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
The invention discloses a carbon dioxide collecting system of an oxygen-enriched combustion boiler coupled with an air separation device, which comprises a flue gas treatment device, a desublimator, a recooler, a liquefaction boosting chamber, a heat exchanger and other devices. The invention uses the low-temperature oxygen prepared by the air separation device to sublimate the carbon dioxide into the easy-to-store dry ice, and uses the dry ice to sublimate to obtain the easy-to-transport liquid carbon dioxide; meanwhile, condensed water is introduced to perform interstage cooling on the compressed air, and liquid oxygen and low-temperature nitrogen obtained by dry ice and rectification are used for reducing the temperature of the compressed air, so that the coupling between a boiler and an air separation device is realized, and the energy consumption of air separation equipment is reduced; in addition, oxygen for sublimating carbon dioxide is introduced into the refrigerating system, and the residual cold energy is utilized to realize external cooling.
Description
Technical Field
The invention relates to the technical field of industrial waste gas treatment, in particular to a carbon dioxide collecting system of an oxygen-enriched combustion boiler coupled with an air separation device.
Background
The high carbon dioxide collection cost becomes an important reason for restricting the large-scale application of the carbon dioxide collection technology. Therefore, reducing carbon dioxide collection costs has become an important research direction for low carbon production.
Compared with the traditional boiler, the oxygen-enriched combustion boiler takes the mixed gas of oxygen and carbon dioxide as a combustion improver, and compared with the traditional boiler, the carbon dioxide concentration in the tail gas is high, the existing patent mainly adopts a low-temperature desublimation/liquefaction method to collect carbon dioxide, but less technology of applying oxygen cooling capacity to a carbon dioxide collecting process is available. Patent 1-an oxygen-enriched combustion tail gas treatment system adopting a low-temperature desublimation method, which uses low-temperature nitrogen gas prepared by an air separation device to desublimate carbon dioxide into dry ice and place the dry ice into a sealing chamber, the dry ice sublimates in the sealing chamber to raise the pressure in the chamber, so that liquid carbon dioxide is obtained, but the sealing plate is opened and closed to cause leakage of the sealing chamber, so that the liquefaction rate of the carbon dioxide is reduced; in addition, the air separation device generally uses a compressor to compress air, and then uses refrigeration to liquefy the air, so that the energy consumption is high. Patent 2-a low-temperature carbon capture system based on dry ice melting cold energy recovery and a working method thereof are improved aiming at patent 1, low-temperature high-concentration brine, low-temperature refrigerant and isopentane with the temperature not higher than minus 80 ℃ are respectively utilized for drying, precooling and desublimation treatment of flue gas to obtain dry ice crystals, and dry ice sublimation is utilized in a sealed chamber to obtain liquid carbon dioxide, but the system has a complex structure, and high-concentration brine is easy to cause scaling corrosion of equipment.
Disclosure of Invention
The invention aims at providing a carbon dioxide collecting system of an oxycombustion boiler coupled with an air separation device aiming at the oxycombustion boiler.
The invention is realized by the following technical scheme:
a carbon dioxide collecting system of an oxygen-enriched combustion boiler coupled with an air separation device comprises a flue gas treatment device, a desublimator, a recooler, a liquefaction boosting chamber, a refrigerator and a heat exchanger;
the outlet of the flue gas treatment device is connected with the first inlet of the flue gas condenser; the outlet of the flue gas condenser is connected with the first inlet of the flue gas primary precooler; the first outlet of the first-stage flue gas precooler is connected with the first inlet of the second-stage flue gas precooler; the first outlet of the smoke secondary precooler is connected with the first inlet of the gas-water separator, and the second outlet of the smoke secondary precooler is connected with the third inlet of the smoke primary precooler; the first outlet of the gas-water separator is connected with the first inlet of the desublimation device, and the second outlet of the gas-water separator is connected with the second inlet of the flue gas condenser; the first outlet of the desublimation device is connected with the inlet of the solid-liquid separator, and the second outlet of the desublimation device is connected with the second inlet of the primary flue gas precooler through the air extraction equipment; the first outlet of the recooler is connected with the second inlet of the desublimator, and the second outlet is connected with the second inlet of the condenser; the first outlet of the solid-liquid separator is connected with the first inlet of the liquefaction boosting chamber through a one-way valve, and the second outlet of the solid-liquid separator is connected with the second inlet of the recooler; the second outlet of the liquefaction boosting chamber is converged into the main pipeline and is connected with the first inlet of the refrigerator; the first outlet of the heat exchanger is connected with the second inlet of the liquefaction boosting chamber through a branch, the first outlet of the heat exchanger is connected with the first inlet of the refrigerator through a main pipeline, and the second outlet of the heat exchanger is connected with the second inlet of the interstage cooler; the first outlet of the refrigerator is connected with the inlet of the air liquefier, and the second outlet of the refrigerator is connected with the first inlet of the recooler; the outlet of the air liquefier is connected with the inlet of the rectifying tower; the first outlet of the rectifying tower is connected with the second inlet of the refrigerator; the first inlet of the interstage cooler is connected with the outlet of the primary compressor, the first outlet is connected with the inlet of the secondary compressor, and the second outlet is connected with the feed water heater; the first outlet of the condenser is connected with the inlet of the evaporator, and the second outlet of the condenser is connected with the second inlet of the smoke secondary precooler.
The invention is further improved in that a valve is arranged on a branch line connecting the first outlet of the heat exchanger and the second inlet of the liquefaction boosting chamber.
The invention is further improved in that the liquefaction boosting chamber is used for storing dry ice to obtain liquid carbon dioxide.
A further improvement of the invention is that the one-way valve is used for the passage of dry ice and prevents the passage of gas.
The invention is further improved in that the solid-liquid separator is used for separating dry ice grains from the coolant, so as to realize collection and storage of carbon dioxide and recycling of the coolant.
The invention is further improved in that the recooler is used for realizing heat exchange between the low-temperature oxygen and the coolant to obtain the low-temperature coolant.
The invention is further improved in that the sublimator is used for realizing the mixed heat exchange of the flue gas and the low-temperature coolant.
The invention is further improved in that the primary flue gas precooler and the secondary flue gas precooler are used for realizing heat exchange between oxygen and flue gas.
The invention is further improved in that the refrigerator is used for cooling the compressed air, and the temperature of the compressed air is further reduced by utilizing the low-temperature nitrogen and liquid oxygen obtained in the rectification process.
A further improvement of the invention is that the inter-stage cooler uses condensed water to cool the compressed air, bringing the compression process close to isothermal compression.
The invention has at least the following beneficial technical effects:
the invention takes the oxygen-enriched combustion boiler as a target object, combines the operation characteristics of the boiler, is coupled with air separation equipment, adopts a low-temperature desublimation method to collect carbon dioxide, and has the following advantages:
first: the condensed water is used for carrying out interstage cooling on the compressed air, so that the compression process is close to isothermal compression, the energy consumption of the compressor is reduced, and meanwhile, the low-temperature nitrogen and liquid oxygen coldness are used for further cooling the compressed air, so that the refrigeration energy consumption of air separation equipment can be reduced;
second,: fully drying and pre-cooling the flue gas and a low-temperature coolant to exchange heat in a desublimation device, and de-sublimating carbon dioxide into dry ice to form slurry with dry ice grains, and sending non-condensable gas into a flue gas primary pre-cooler by an air extraction device to cool the flue gas, so as to fully utilize cold energy;
third,: the dry ice obtained through the solid-liquid separator enters the liquefaction boosting chamber through the one-way valve, liquid carbon dioxide is obtained by sublimation and self-boosting of the dry ice, the one-way valve can ensure good tightness of the boosting chamber, the liquefaction rate of the carbon dioxide is improved, and meanwhile, the compressed air branch is arranged, so that the dry ice can be heated by compressed air, and the liquefaction process is accelerated;
fourth,: the low-temperature oxygen reduces the temperature of the coolant in the recooler, and then the two-stage flue gas precooler absorbs the flue gas waste heat to reduce the flue gas temperature, so that the full utilization of oxygen cooling capacity is realized, and the flue gas waste heat is recovered to enable the oxygen to obtain a larger temperature rise, thereby facilitating the subsequent combustion utilization.
In summary, the invention provides a carbon dioxide collection system of an oxyfuel combustion boiler coupled with air separation equipment. The invention adopts the one-way valve to ensure the tightness of the boosting chamber, and simultaneously uses the condensed water to carry out interstage cooling on the compressed air, and uses the dry ice, the liquid oxygen obtained by rectification and the low-temperature nitrogen to reduce the temperature of the compressed air, thereby reducing the energy consumption of the air separation equipment and overcoming the problems of easy leakage of the sealing chamber and high energy consumption of the air separation equipment in the patent 1. The invention adopts the residual cold energy of cooling water and oxygen to carry out drying treatment on tail flue gas, and a low-temperature high-concentration brine drying system is not required to be assembled, thereby solving the problem of scale corrosion possibly existing in patent 2 and simplifying the system. In addition, the invention utilizes the residual cold energy of the oxygen to externally cool the flue gas, fully utilizes the cold energy of the oxygen, recovers the waste heat of the tail gas and improves the energy utilization rate.
Drawings
FIG. 1 is a block diagram of a carbon dioxide collection system of an oxycombustion boiler coupled with an air separation device according to the present invention.
Reference numerals illustrate:
1. a flue gas treatment device; 2. a flue gas condenser; 3. a flue gas primary precooler; 4. a secondary precooler for flue gas; 5. a gas-water separator; 6. a desublimation device; 7. a recooler; 8. a solid-liquid separator; 9. a one-way valve; 10. a liquefaction boost chamber; 11. a first stage compressor; 12. a secondary compressor; 13. a heat exchanger; 14. a refrigerator; 15. an air liquefier; 16. a rectifying tower; 17. an inter-stage cooler; 18. a feedwater heater; 19. a condenser; 20. an evaporator; 21. an air extraction device; 22. and (3) a valve.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.
As shown in fig. 1, the invention provides a carbon dioxide collecting system of an oxycombustion boiler coupled with an air separation device, which comprises the following steps,
step 1, an air separation device is the most main energy consumption process in the air compression process, and the exhaust steam condensate water of a steam turbine is utilized to perform interstage cooling on the compressed air, so that the compression process is close to an isothermal compression process, the power consumption of a compressor can be reduced, and meanwhile, the heat energy of the compressed air is recovered to heat the condensate water, so that the energy utilization rate is improved;
step 2, exchanging heat between liquid oxygen and low-temperature nitrogen obtained by rectification of an air separation device and compressed air, and reducing the temperature of the compressed air by utilizing partial cold energy of the liquid oxygen and the total cold energy of the nitrogen so as to reduce the refrigeration energy consumption required by the subsequent liquefied air;
step 3, when the temperature of oxygen to be used for cooling compressed air is increased to about minus 90 ℃, sending the oxygen into a recooler 7 to exchange heat with a coolant (such as isopentane) to reduce the temperature of the coolant to minus 80 ℃ or lower, then sending the oxygen into a condenser 19 to condense high-temperature refrigerant to realize external cooling, and finally sequentially passing through a flue gas secondary precooler 4 and a flue gas primary precooler 3 to exchange heat with tail flue gas to reduce the temperature of the flue gas, and simultaneously, increasing the temperature of the oxygen to facilitate the subsequent combustion and utilization;
step 4, after the tail flue gas is pretreated (including desulfurization and dust removal treatment), heat exchange and cooling are carried out on the tail flue gas and cooling water in a flue gas condenser 2, water vapor is condensed and discharged, primary drying of the flue gas is realized, then the flue gas is cooled step by step through a flue gas primary precooler 3 and a flue gas secondary precooler 4, water is further removed through a gas-water separator 5, finally the flue gas is led into a desublimator 6 to contact with a low-temperature coolant, carbon dioxide is sublimated in the coolant to form dry ice grains, non-condensed gas is pumped out by an air pumping device 21, and the flue gas is cooled by the flue gas primary precooler 3, so that full utilization of cold energy of the non-condensed gas is realized;
and 5, enabling the slurry discharged from the desublimation device 6 to flow into a solid-liquid separator 8, and enabling the separated dry ice grains to fall into a liquefaction boosting chamber 10 through a one-way valve 9. In particular, the sublimation of dry ice may be accelerated by the bypass introduction of a portion of compressed air. When the pressure and temperature of the carbon dioxide in the liquefaction boosting chamber 10 reach above the corresponding parameters of the three-phase point (0.52 MPa, 56.6 ℃ below zero), liquid carbon dioxide can be obtained, and the separated coolant is sent into the recooler 7 for cooling, so that recycling is realized.
The invention discloses a carbon dioxide collecting system of an oxyfuel combustion boiler coupled with an air separation device, which concretely comprises the following components:
an inter-stage cooler 17 for cooling the compressed air by using condensed water, so that the compression process approaches isothermal compression, and the compressor energy is reduced;
the heat exchanger 13 is used for cooling the compressed air by utilizing condensed water, so that the temperature of the air is reduced, and the subsequent liquefaction is facilitated;
the refrigerator 14 is used for cooling the compressed air, and the low-temperature nitrogen (about 180 ℃ below zero) and liquid oxygen obtained in the rectification process are utilized to further reduce the temperature of the compressed air and reduce the refrigeration energy consumption required in the air liquefaction process;
the flue gas condenser 2 is used for condensing water vapor in the flue gas, removing water in the flue gas and improving the carbon dioxide collection purity;
the flue gas primary precooler 3 and the flue gas secondary precooler 4 are used for realizing heat exchange between oxygen and flue gas, cooling the flue gas by utilizing the residual cold energy of the oxygen, and recovering the flue gas waste heat to heat the oxygen so as to facilitate the subsequent combustion and utilization;
a gas-water separator 5 for further separating and removing moisture in the flue gas;
the desublimator 6 is used for realizing the mixed heat exchange of the flue gas and a low-temperature coolant (the temperature is minus 80 ℃ and below), the carbon dioxide is sublimated in the coolant to form small ice crystals, and the non-condensing gas is pumped to the flue gas primary precooler 3 by the pumping equipment 21 to cool the flue gas;
the solid-liquid separator 8 is used for separating dry ice grains from the coolant to realize collection and storage of carbon dioxide and circulation regeneration of the coolant;
a recooler 7 for realizing heat exchange between the low-temperature oxygen (below-90 ℃) and the coolant to obtain a low-temperature coolant;
and a liquefaction pressurizing room 10 for storing dry ice to obtain liquid carbon dioxide. And (3) sublimating dry ice to raise the pressure in the closed chamber, and obtaining liquid carbon dioxide when the pressure and the temperature of the carbon dioxide reach the corresponding parameters (0.52 MPa, 56.6 ℃ below zero) of the triple point. In particular, part of the compressed air may be introduced through the bypass to heat the dry ice to accelerate the carbon dioxide liquefaction process.
The check valve 9 only allows dry ice to pass through, prevents gas from passing through, ensures the tightness of the liquefaction boosting chamber 10, and improves the carbon dioxide liquefaction rate.
As shown in fig. 1, the outlet of the flue gas treatment device 1 is connected with the first inlet of the flue gas condenser 2; the outlet of the flue gas condenser 2 is connected with the first inlet of the flue gas primary precooler 3; the first outlet of the first-stage flue gas precooler 3 is connected with the first inlet of the second-stage flue gas precooler 4; the first outlet of the flue gas secondary precooler 4 is connected with the first inlet of the gas-water separator 5, and the second outlet is connected with the third inlet of the flue gas primary precooler 3; the first outlet of the gas-water separator 5 is connected with the first inlet of the desublimation device 6, and the second outlet is connected with the second inlet of the flue gas condenser 2; the first outlet of the desublimation device 6 is connected with the inlet of the solid-liquid separator 8, and the second outlet is connected with the second inlet of the flue gas primary precooler 3 through the air extraction equipment 21; the first outlet of the recooler 7 is connected to the second inlet of the desublimator 6, and the second outlet is connected to the second inlet of the condenser 19; the first outlet of the solid-liquid separator 8 is connected with the first inlet of the liquefaction boosting chamber 10 through the one-way valve 9, and the second outlet is connected with the second inlet of the recooler 7; the second outlet of the liquefaction boost chamber 10 merges into the main pipeline and is connected with the first inlet of the refrigerator 14; the first outlet of the heat exchanger 13 is connected with the second inlet of the liquefaction boosting chamber 10 through a branch, is connected with the first inlet of the refrigerator 14 through a main pipeline, and is connected with the second inlet of the interstage cooler 17; the first outlet of the refrigerator 14 is connected with the inlet of the air liquefier 15, and the second outlet is connected with the first inlet of the recooler 7; the outlet of the air liquefier 15 is connected with the inlet of the rectifying tower 16; the first outlet of rectifying column 16 is connected to the second inlet of refrigerator 14; the first inlet of the inter-stage cooler 17 is connected with the outlet of the first-stage compressor 11, the first outlet is connected with the inlet of the second-stage compressor 12, and the second outlet is connected with the feed water heater 18; the first outlet of the condenser 19 is connected with the inlet of the evaporator 20, and the second outlet is connected with the second inlet of the flue gas secondary precooler 4.
The specific process of the invention is as follows:
1. air molecule system
The air molecule system comprises a first-stage compressor 11, a second-stage compressor 12, an inter-stage cooler 17, a heat exchanger 13, a refrigerator 14, an air liquefier 15 and a rectifying tower 16.
The primary compressor 11 increases the pressure and temperature of the air, and the condensed water is used for cooling the compressed air in the inter-stage cooler 17, so that the compression process is approximately isothermal compression, and the energy consumption of the compressor is reduced; the secondary compressor 12 then uses the condensed water to cool the compressed air in the heat exchanger 13 for subsequent liquefaction of the air. In particular, the compressed air can be pumped out by the valve 22 and sent into the liquefaction boosting chamber 10 through the branch for heating the dry ice in the liquefaction boosting chamber 10, accelerating the carbon dioxide liquefaction process, and the valve 22 can control the air flow of the branch according to the adjustment opening. And then the branch air and the main flow are mixed and sent into the refrigerator 14, and the low-temperature nitrogen and liquid oxygen exchange heat with the compressed air, so that the air temperature is reduced, the subsequent liquefaction is facilitated, and the refrigeration energy consumption is reduced. The nitrogen is discharged after being fully utilized, and the oxygen is fed into the recooler 7 after the temperature of the oxygen is raised to about 90 ℃ below zero. The air liquefier 15 liquefies the compressed air, and then sends the liquefied air into the rectifying tower 16 for separation, thereby obtaining low-temperature nitrogen and liquid oxygen.
2. De-sublimating subsystem
The desublimation subsystem comprises a flue gas condenser 2, a flue gas primary precooler 3, a flue gas secondary precooler 4, a gas-water separator 5, a recooler 7, a desublimation device 6, a solid-liquid separator 8 and a liquefaction boosting chamber 10.
The flue gas after desulfurization and dust removal is subjected to heat exchange with cooling water in a flue gas condenser 2, water vapor is condensed and discharged to finish pre-dehydration and drying, then the flue gas is subjected to heat exchange with oxygen in a flue gas primary precooler 3 and a flue gas secondary precooler 4, the temperature is reduced step by step, the water vapor is further condensed, and then the flue gas is further dried through a gas-water separator 5. In particular, the condensate water obtained in the gas-water separator 5 is introduced into the flue gas condenser 2 to condense the flue gas. The low-temperature oxygen exchanges heat with the coolant in the recooler 7, the low-temperature coolant at the outlet of the recooler 7 is introduced into the desublimator 6 to exchange heat with the dry flue gas at the outlet of the gas-water separator 5, carbon dioxide is condensed into dry ice grains in the coolant, the formed slurry is separated by the solid-liquid separator 8, the dry ice grains enter the liquefaction boosting chamber 10 through the one-way valve 9, and the coolant returns to the recooler 7 to cool and circularly work. In particular, the coolant should be selected from working media which are non-corrosive, low in solidifying point, low in carbon dioxide absorptivity and the like and meet the production requirements. The dry ice sublimates in the pressure-increasing chamber 10, and the pressure in the sealing chamber is increased to 0.52MPa or more, thereby obtaining liquid carbon dioxide. In particular, a compressed air stream may be fed into liquefaction boost chamber 10 through valve 22 to accelerate the liquefaction process, and the opening of valve 22 may vary with load. In particular, the check valve 9 allows only one-way passage of dry ice grains, and does not allow passage of gas, so that the air tightness of the pressure increasing chamber can be ensured. In particular, the non-condensing gas in the desublimation device 6 is pumped out by the pumping device 21 and is sent into the primary flue gas precooler 3 to cool the flue gas, so as to realize the full utilization of cold energy.
3. Oxygen residual cold utilization subsystem
The oxygen residual cold utilization subsystem comprises a condenser 19, a flue gas primary precooler 3 and a flue gas secondary precooler 4.
Oxygen at the outlet of the recooler 7 enters a condenser 19 to exchange heat with the refrigerant, so that the oxygen is condensed, and external cooling is realized; the oxygen at the outlet of the condenser 19 exchanges heat with the flue gas through a two-stage flue gas precooler to realize precooling of the flue gas, and the waste heat of the flue gas is recovered to raise the temperature of the oxygen so as to facilitate subsequent combustion and utilization.
While the invention has been described in detail in the foregoing general description and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.
Claims (10)
1. The carbon dioxide collecting system of the oxyfuel combustion boiler coupled with the air separation device is characterized by comprising a flue gas treatment device (1), a desublimator (6), a recooler (7), a liquefaction boosting chamber (10), a refrigerator (14) and a heat exchanger (13);
the outlet of the flue gas treatment device (1) is connected with the first inlet of the flue gas condenser (2); the outlet of the flue gas condenser (2) is connected with the first inlet of the flue gas primary precooler (3); the first outlet of the first-stage flue gas precooler (3) is connected with the first inlet of the second-stage flue gas precooler (4); the first outlet of the smoke secondary precooler (4) is connected with the first inlet of the gas-water separator (5), and the second outlet is connected with the third inlet of the smoke primary precooler (3); the first outlet of the gas-water separator (5) is connected with the first inlet of the desublimation device (6), and the second outlet is connected with the second inlet of the flue gas condenser (2); the first outlet of the desublimation device (6) is connected with the inlet of the solid-liquid separator (8), and the second outlet is connected with the second inlet of the flue gas primary precooler (3) through the air extraction equipment (21); the first outlet of the recooler (7) is connected with the second inlet of the desublimator (6), and the second outlet is connected with the second inlet of the condenser (19); the first outlet of the solid-liquid separator (8) is connected with the first inlet of the liquefaction boosting chamber (10) through a one-way valve (9), and the second outlet is connected with the second inlet of the recooler (7); the second outlet of the liquefaction boosting chamber (10) is converged into the main pipeline and is connected with the first inlet of the refrigerator (14); the first outlet of the heat exchanger (13) is connected with the second inlet of the liquefaction boosting chamber (10) through a branch, is connected with the first inlet of the refrigerator (14) through a main pipeline, and is connected with the second inlet of the interstage cooler (17); the first outlet of the refrigerator (14) is connected with the inlet of the air liquefier (15), and the second outlet is connected with the first inlet of the recooler (7); the outlet of the air liquefier (15) is connected with the inlet of the rectifying tower (16); the first outlet of the rectifying tower (16) is connected with the second inlet of the refrigerator (14); the first inlet of the inter-stage cooler (17) is connected with the outlet of the primary compressor (11), the first outlet is connected with the inlet of the secondary compressor (12), and the second outlet is connected with the feed water heater (18); the first outlet of the condenser (19) is connected with the inlet of the evaporator (20), and the second outlet is connected with the second inlet of the flue gas secondary precooler (4).
2. The carbon dioxide collection system of an oxycombustion boiler coupled with an air separation device according to claim 1, characterized in that a valve (22) is arranged in the branch where the first outlet of the heat exchanger (13) is connected to the second inlet of the liquefaction boosting chamber (10).
3. The carbon dioxide collection system of an oxycombustion boiler coupled with an air separation unit according to claim 1, wherein the liquefaction pressurization chamber (10) is used for storing dry ice to obtain liquid carbon dioxide.
4. A carbon dioxide collection system for an oxycombustion boiler coupled with an air separation unit according to claim 3, characterized by a one-way valve (9) for the passage of dry ice and preventing the passage of gases.
5. A carbon dioxide collecting system of an oxycombustion boiler coupled with an air separation device according to claim 3, wherein the solid-liquid separator (8) is used for separating dry ice crystal grains and coolant, so as to realize the collection, storage and recycling of the coolant.
6. The carbon dioxide collection system of an oxycombustion boiler coupled with an air separation unit according to claim 1, wherein the recooler (7) is configured to exchange heat between the cryogenic oxygen and the coolant to obtain the cryogenic coolant.
7. A carbon dioxide collection system of an oxycombustion boiler coupled with an air separation unit according to claim 1, characterized in that the desublimator (6) is adapted to realize a mixed heat exchange of flue gas with a low temperature coolant.
8. The carbon dioxide collection system of the oxy-combustion boiler coupled with the air separation device according to claim 1, wherein the primary flue gas precooler (3) and the secondary flue gas precooler (4) are used for realizing heat exchange between oxygen and flue gas.
9. A carbon dioxide collection system for an oxycombustion boiler coupled with an air separation unit according to claim 1, wherein the refrigerator (14) is configured to cool the compressed air and further reduce the temperature of the compressed air by utilizing the cryogenic nitrogen and liquid oxygen obtained from the rectification process.
10. An oxycombustion boiler carbon dioxide collection system coupled with an air separation plant according to claim 1, characterized in that the inter-stage cooler (17) uses condensed water to cool the compressed air, bringing the compression process close to isothermal compression.
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| CN202410037452.0A CN117869920A (en) | 2024-01-10 | 2024-01-10 | Carbon dioxide collecting system of oxygen-enriched combustion boiler coupled with air separation device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410037452.0A CN117869920A (en) | 2024-01-10 | 2024-01-10 | Carbon dioxide collecting system of oxygen-enriched combustion boiler coupled with air separation device |
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