CN116180103A - System for synthesizing green ammonia based on liquid air energy storage and high-temperature electrolysis - Google Patents
System for synthesizing green ammonia based on liquid air energy storage and high-temperature electrolysis Download PDFInfo
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 184
- 239000007788 liquid Substances 0.000 title claims abstract description 115
- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 101
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 91
- 238000004146 energy storage Methods 0.000 title claims abstract description 59
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 86
- 239000001257 hydrogen Substances 0.000 claims abstract description 62
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 62
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 58
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 55
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 55
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 40
- 238000000926 separation method Methods 0.000 claims abstract description 39
- 238000010248 power generation Methods 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 37
- 230000008569 process Effects 0.000 claims abstract description 31
- 238000006243 chemical reaction Methods 0.000 claims abstract description 30
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 29
- 150000002431 hydrogen Chemical class 0.000 claims abstract description 8
- 239000007787 solid Substances 0.000 claims description 33
- 238000003860 storage Methods 0.000 claims description 32
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 22
- 239000001301 oxygen Substances 0.000 claims description 22
- 229910052760 oxygen Inorganic materials 0.000 claims description 22
- 239000007789 gas Substances 0.000 claims description 13
- 238000001035 drying Methods 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
- 238000002309 gasification Methods 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 6
- 230000005611 electricity Effects 0.000 description 13
- 239000012736 aqueous medium Substances 0.000 description 11
- 238000004519 manufacturing process Methods 0.000 description 9
- 238000004891 communication Methods 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 8
- 230000009471 action Effects 0.000 description 5
- 238000012546 transfer Methods 0.000 description 5
- 238000013461 design Methods 0.000 description 4
- 238000005194 fractionation Methods 0.000 description 4
- 239000012528 membrane Substances 0.000 description 4
- 238000004064 recycling Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000004880 explosion Methods 0.000 description 3
- 230000010354 integration Effects 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000035899 viability Effects 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/02—Hydrogen or oxygen
- C25B1/04—Hydrogen or oxygen by electrolysis of water
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/04—Purification or separation of nitrogen
- C01B21/0405—Purification or separation processes
- C01B21/0433—Physical processing only
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/02—Preparation, purification or separation of ammonia
- C01C1/04—Preparation of ammonia by synthesis in the gas phase
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/60—Constructional parts of cells
- C25B9/65—Means for supplying current; Electrode connections; Electric inter-cell connections
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K27/00—Plants for converting heat or fluid energy into mechanical energy, not otherwise provided for
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B41/00—Pumping installations or systems specially adapted for elastic fluids
- F04B41/02—Pumping installations or systems specially adapted for elastic fluids having reservoirs
Abstract
The invention relates to a system for synthesizing green ammonia based on liquid air energy storage and high-temperature electrolysis, which comprises the following principles: the renewable energy power generation system is used for providing electric energy; the liquid air energy storage unit is used for receiving the electric power of the renewable energy power generation system to treat the outside air and storing the electric energy in the form of liquid air, and simultaneously converting the liquid air into a gaseous form and converting the energy in the process into electric energy; the air separation unit is connected with the liquid air energy storage unit and receives the liquid air from the liquid air energy storage unit for separation treatment to obtain nitrogen; the electrolysis unit receives the electric power of the renewable energy power generation system to carry out water electrolysis reaction to obtain hydrogen, and when the renewable energy power generation system is insufficient in power supply, the electrolysis unit is driven by the electric power generated by the liquid state conversion of the liquid air energy storage unit to continue the electrolysis reaction; the ammonia synthesis unit receives the nitrogen from the air separation unit and the hydrogen from the electrolysis unit to perform ammonia synthesis, and simultaneously recovers and transmits the heat generated in the reaction process to the electrolysis unit. The electric ammonia conversion efficiency of the invention is greatly improved.
Description
Technical Field
The invention relates to the technical field of green ammonia synthesis, in particular to a system for synthesizing green ammonia based on liquid air energy storage and high-temperature electrolysis.
Background
Currently, with the continuous decrease of photovoltaic and wind power costs, a production process of producing hydrogen by electrolysis based on renewable energy sources and further synthesizing green ammonia (ammonia synthesized by decomposing renewable energy sources by electrolysis of water, namely green ammonia) is becoming an increasingly viable option. However, the overall energy efficiency of the electricity-ammonia-electricity route is relatively low and economic viability is low compared to other chemical energy storage routes. The use of green ammonia for energy storage requires further efficiency improvements and lower production costs.
The conventional power ammonia transfer process consists of three main parts: water electrolysis device for generating H2 and N generation device 2 Air Separation Unit (ASU) or Pressure Swing Adsorption (PSA) unit, and use of N 2 And H 2 Production of NH 3 A Hapto (HB) synthesizer. The electrolyzer is the most critical unit of these, and currently there are three main electrolysis techniques: alkaline Electrolysis Cells (AEC), proton Exchange Membrane Electrolysis Cells (PEMEC) and solid oxide high temperature electrolysis cells (SOEC).
Because of the intermittent and fluctuating nature of renewable energy supplies, the electrical ammonia conversion process directly coupled with new energy cannot be operated continuously, and therefore large hydrogen storage tanks are often required to ensure the safety and reliability of subsequent processes. The current process flow mainly has the following problems.
(1) The electrolysis device and the haper synthesis device are independently operated, the capacity design of the electrolysis tank is usually larger than the capacity of the subsequent synthesis device in order to adapt to the fluctuation of renewable energy sources,causing an increase in investment costs; in addition, in order to ensure that the ammonia plant can be maintained to operate under a relatively stable load, the capacity design of the hydrogen storage tank needs to be correspondingly improved, but a large amount of H is stored at high pressure 2 There are potential safety hazards of leakage and explosion, and equipment price and maintenance cost are relatively high.
(2) The current green electricity ammonia conversion mostly adopts low-temperature electrolytic tanks (alkaline electrolytic tanks, proton exchange membrane electrolytic tanks and the like), the technology is mature, the following performance on new energy is good, and the fluctuation of the output of renewable energy sources can be better adapted. However, the low temperature electrolysis process is less efficient than high temperature electrolysis (solid oxide high temperature electrolysis cell); in addition, since the electrolysis device and the ammonia synthesis device often operate independently, no reasonable heat integration is performed, thereby causing further reduction in overall conversion efficiency of green electroconversion ammonia.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a system for synthesizing green ammonia based on liquid air energy storage and high-temperature electrolysis, which comprises the following components:
the renewable energy power generation system is used for providing electric energy;
the liquid air energy storage unit is communicated with the renewable energy power generation system, receives the electric power of the renewable energy power generation system to treat the outside air and store electric energy in the form of liquid air, and can convert the liquid air into a gaseous form and convert the energy in the process into electric energy;
the air separation unit is communicated with the liquid air energy storage unit and receives the liquid air from the liquid air energy storage unit for separation treatment to obtain nitrogen;
the electrolysis unit is electrically communicated with the renewable energy power generation system and the liquid air energy storage unit, receives the electric power of the renewable energy power generation system to perform water electrolysis reaction to obtain hydrogen, and when the power supply of the renewable energy power generation system is insufficient, the electrolysis unit is driven by the electric power generated by the liquid conversion of the liquid air energy storage unit to continue the electrolysis reaction;
and the ammonia synthesis unit is communicated with the air separation unit and the electrolysis unit, receives the nitrogen from the air separation unit and the hydrogen from the electrolysis unit to perform ammonia synthesis, and simultaneously recovers and transmits heat generated in the reaction process to the electrolysis unit.
In particular, through the liquid air energy storage unit, on the one hand, surplus electric quantity of the renewable energy power generation system can be received, the electric power is used for driving a machine to store liquid air for air treatment, and when the electric power is insufficient, the power conversion can be performed through the process of converting compressed air into gaseous air for power generation. More specifically, the hydrogen is obtained through the water electrolysis reaction through the arranged electrolysis unit to replace the design of the prior large-scale hydrogen storage tank, so that on one hand, the sufficient hydrogen supply can be ensured, on the other hand, the risks of leakage and explosion of high-pressure mass storage in the hydrogen storage link are reduced, and the equipment cost and the maintenance equipment cost are also reduced.
Further, the liquid air energy storage unit comprises a filtering and drying device, an air compressor, a cooling device and a liquid air storage tank which are sequentially communicated; the filtering and drying device is used for receiving outside air, and the liquid air storage tank is communicated with the air separation unit; outside air is firstly purified and dried through a filtering and drying device, then is sent into an air compressor for compression, the obtained high-pressure air is cooled in a cooling device and condensed into liquid air, and finally is sent into a liquid air storage tank for storage. Specifically, when the power of the renewable energy power generation system is excessive enough to load the electrolysis unit, part of the power can be used for providing power for devices such as an air compressor, the outside air is subjected to liquidation treatment, liquid air is stored, and the liquid air is stored in a liquid air storage tank; when the renewable energy power generation system is insufficient in electric power and cannot fully bear the electrolytic unit, the liquid air in the liquid air storage tank is converted into gaseous air to perform energy conversion, the energy is converted into power of a generator to drive the generator to generate electricity, and then the electricity is used for water electrolysis reaction performed by the electrolytic unit.
Further, the air separation unit comprises a high-pressure rectifying tower, an expansion valve and a low-pressure rectifying tower; the high-pressure rectifying tower is communicated with the liquid air energy storage unit, and the low-pressure rectifying tower is communicated with the ammonia synthesis unit; the liquid air from the liquid air energy storage unit is rectified through a high-pressure rectifying tower, then is sent into an expansion valve to be boosted, finally is sent into a low-pressure rectifying tower, and finally is fractionated to obtain nitrogen. It should be understood that the rectification fractionation is to separate the chemical products from various mixed gases by different boiling points, and specifically, the fractionation separation and recovery collection of oxygen in liquid air can be performed simultaneously in the rectification process.
Further, the ammonia synthesis unit comprises a first-stage reactor, a second-stage reactor and a third-stage reactor which are sequentially communicated; the first-stage reactor is communicated with the air separation unit and the electrolysis unit and respectively receives nitrogen and hydrogen from the air separation unit and the electrolysis unit to carry out nitrogen synthesis reaction; and the second-stage reactor and the third-stage reactor receive the mixed gas from the first-stage reactor and continue to carry out nitrogen synthesis reaction and mixed gas delivery. Specifically, ammonia synthesis is performed under conditions of high temperature and high pressure and a catalyst, and the reaction is exothermic. Specifically, the three reactors further increase the reaction time, so that the synthesis reaction can be more fully performed.
Further, the ammonia synthesis unit further comprises an ammonia separation device; the ammonia separation device is communicated with the third-stage reactor, receives the mixed gas after the synthesis reaction of the three reactors, and separates ammonia.
Further, a third water heat exchanger is arranged between the first-stage reactor and the second-stage reactor, a second water heat exchanger is arranged between the second-stage reactor and the third-stage reactor, and a first water heat exchanger is arranged at the outlet of the third-stage reactor; the first water heat exchanger, the second water heat exchanger and the third water heat exchanger are in heat exchange water communication, and the heat generated in the ammonia synthesis process is absorbed by the three water heat exchangers respectively and is transmitted in a circulating way. Specifically, through a plurality of heat exchangers that set up, absorb the conversion to the heat that releases in the ammonia synthesis process, aqueous medium is introduced from first level water heat exchanger heat, and first water heat exchanger, second water heat exchanger and third water heat exchanger are passed through in proper order, and the gradual absorption is at each level the reaction heat that produces in the reactor to carry out heat transfer through aqueous medium.
Further, the electrolysis unit comprises a solid oxide high-temperature electrolysis tank, an oxygen compressor and a hydrogen compressor; one end of the hydrogen compressor is connected with the solid oxide high-temperature electrolytic tank, and the other end of the hydrogen compressor is connected with the first-stage reactor; one end of the oxygen compressor is communicated with the solid oxide high-temperature electrolytic tank, and the other end of the oxygen compressor is communicated with the first-stage reactor. Specifically, the solid oxide high-temperature electrolytic tank is efficient and rapid in hydrogen production, and no hydrogen storage equipment is needed. More specifically, the solid oxide high-temperature electrolytic tank is subjected to hydrolysis reaction to obtain hydrogen and oxygen, the oxygen is recovered after being treated by an oxygen compressor, and the hydrogen enters a first-stage reactor after being treated by the hydrogen compressor and is subjected to synthesis reaction with nitrogen to generate ammonia.
Further, the electrolysis unit further comprises a fourth hydrothermal exchanger and a fifth hydrothermal exchanger; the fourth hydrothermal exchanger is arranged between the hydrogen compressor and the solid oxide high-temperature electrolytic tank, and the fifth hydrothermal exchanger is arranged between the oxygen compressor and the solid oxide high-temperature electrolytic tank; the fourth water heat exchanger is communicated with the heat exchange water in the third water heat exchanger, the fifth water heat exchanger is communicated with the heat exchange water in the fourth water heat exchanger, and the heat exchange water in the fifth water heat exchanger is communicated with the solid oxide high-temperature electrolytic tank. Specifically, the aqueous medium (heat exchange water) from the third water heat exchanger enters the fourth water heat exchanger to further absorb heat carried in hydrogen generated by the electrolysis reaction, then the aqueous medium continuously enters the fifth water heat exchanger and absorbs heat carried in oxygen generated by the electrolysis reaction, and then the aqueous medium enters the solid oxide high-temperature electrolytic tank, and the aqueous medium can enter in the form of water vapor when entering the solid oxide high-temperature electrolytic tank due to heat absorption by the five water heat exchangers. More specifically, the five hydrothermal exchangers are used for integrally utilizing the heat of the ammonia synthesis unit, so that the utilization of heat energy in the green ammonia synthesis process is further improved, and the overall conversion efficiency of the green electroconversion ammonia is further improved.
Further, the liquid air energy storage unit further comprises a power generation system; the power generation system comprises a gasification heating device, a high-pressure turbine, a medium-pressure turbine, a low-pressure turbine and a generator which are sequentially communicated; the gasification heating device is communicated with the liquid air storage tank, and the generator is communicated with the electrolysis unit. Specifically, after the liquid air stored in the liquid air storage tank is heated by the heating device, the liquid air is converted into power of the generator through the action of the three turbines to drive the generator to generate electricity, and the electricity is applied to the electrolysis unit, especially when the electricity of the renewable energy power generation system is insufficient to maintain chemical reaction in the electrolysis unit.
In summary, the system for synthesizing the green ammonia based on liquid air energy storage and high-temperature electrolysis has the beneficial effects that: in the invention, a hydrogen storage tank is eliminated, the capacity of the electrolysis unit can be properly reduced, and the electrolysis unit and the synthetic ammonia unit can be designed to have the same or close capacity and can operate under constant load; the system can continuously and uninterruptedly run so as to realize high-efficiency production and heat integration of the system level; compared with the conventional electroammonia process (the efficiency is about 50%), the overall efficiency of the invention can be improved to more than 80%, and the process energy efficiency is obviously improved.
The invention also provides a method for synthesizing green ammonia based on liquid air energy storage and high-temperature electrolysis, which is characterized by comprising the following steps:
firstly, storing liquid air, namely storing the outside air in a liquid air form after the outside air is treated;
secondly, preparing nitrogen, and fractionating liquid air to obtain nitrogen;
preparing hydrogen, preparing hydrogen while preparing nitrogen, generating electricity through possible renewable energy sources, and then electrolyzing water vapor by using a solid oxide high-temperature electrolytic tank to obtain hydrogen;
fourthly, ammonia is prepared, and the nitrogen and the hydrogen are subjected to a synthetic reaction to obtain ammonia;
and fifthly, recycling heat, and recycling heat generated in the ammonia synthesis reaction process to a hydrogen preparation link for use while preparing ammonia.
Specifically, the preparation method of the invention is based on liquid air energy storage and high-temperature electrolysis for synthesizing the green ammonia: on one hand, the solid oxide high-temperature electrolytic tank is used for preparing hydrogen, so that the condition that the efficiency of an alkaline electrolytic tank and a proton exchange membrane electrolytic tank is low in the traditional preparation method is avoided; on the other hand, the heat of the exothermic reaction in the ammonia preparation process is recycled to the hydrogen production process, so that the utilization rate of heat energy in the green ammonia synthesis process is further improved.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures.
FIG. 1 is a schematic diagram of the overall system architecture of the present invention;
FIG. 2 is a schematic diagram of a system embodying the present invention;
1. the device comprises a liquid air energy storage unit, an air separation unit, an electrolysis unit, an ammonia synthesis unit and a liquid air energy storage unit, wherein the liquid air energy storage unit, the air separation unit, the electrolysis unit and the ammonia synthesis unit are respectively arranged in sequence;
11. the device comprises a filter drying device, 12, an air compressor, 13, a cooling device, 14, a liquid air storage tank, 15, a gasification heating device, 16, a high-pressure turbine, 17, a medium-pressure turbine, 18, a low-pressure turbine, 19, a generator, 21, a high-pressure rectifying tower, 22, an expansion valve, 23, a low-pressure rectifying tower, 31, a solid oxide high-temperature electrolytic tank, 32, a fifth water heat exchanger, 33, a fourth water heat exchanger, 33, 34, an oxygen compressor, 35, a hydrogen compressor, 41, a first-stage synthesis reactor, 42, a third water heat exchanger, 43, a second-stage synthesis reactor, 44, a second water heat exchanger, 45, a third-stage synthesis reactor, 46, a first water heat exchanger, 47 and an ammonia separation device.
Detailed Description
The present invention will be described in further detail 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.
Referring to fig. 1-2, a system for synthesizing green ammonia based on liquid air energy storage and high temperature electrolysis disclosed by the invention comprises a renewable energy power generation system 5, a liquid air energy storage unit 1, an air separation unit 2, an electrolysis unit 3 and an ammonia synthesis unit 4; the liquid air energy storage unit 1 is electrically communicated with the renewable energy power generation system 5, receives the electric power of the renewable energy power generation system 5 to treat the outside air and store electric energy in the form of liquid air, and can convert the liquid air into a gaseous form and convert the energy in the process into electric energy; the air separation unit 2 is communicated with the liquid air energy storage unit 1 and receives the liquid air from the liquid air energy storage unit 1 for separation treatment to obtain nitrogen; the electrolysis unit 3 is electrically communicated with the renewable energy power generation system 5 and the liquid air energy storage unit 1, receives the electric power of the renewable energy power generation system 5 to perform water electrolysis reaction to obtain hydrogen, and when the renewable energy power generation system 5 is insufficient in power supply, the electrolysis unit is driven by the electric power generated by the liquid conversion gas of the liquid air energy storage unit 1 to continue the electrolysis reaction; the ammonia synthesis unit 4 is communicated with the air separation unit 2 and the electrolysis unit 3, receives the nitrogen from the air separation unit 2 and the hydrogen from the electrolysis unit 3 to perform ammonia synthesis, and simultaneously recovers and transmits the heat generated in the reaction process to the electrolysis unit 3.
In particular, by providing the liquid air energy storage unit 1, on the one hand, it is possible to receive the excess electric energy of the renewable energy power generation system 5, to use this electric power for driving the machine to store the liquid air for air treatment, and, when the electric power supply is insufficient, to perform power conversion for power generation by the process of converting the compressed air into gaseous air. More specifically, the hydrogen is obtained through the water electrolysis reaction through the arranged electrolysis unit 3 to replace the design of the prior large-scale hydrogen storage tank, so that on one hand, the sufficient hydrogen supply can be ensured, on the other hand, the risks of leakage and explosion of high-pressure mass storage in the hydrogen storage link are reduced, and the equipment cost and the maintenance equipment cost are also reduced.
Referring to fig. 2, the liquid air energy storage unit 2 includes a filter drying device 11, an air compressor 12, a cooling device 13 and a liquid air storage tank 14 which are sequentially connected; the filtering and drying device 11 is used for receiving external air, and the liquid air storage tank 14 is communicated with the air separation unit 2; outside air is firstly purified and dried by the filtering and drying device 11, then is sent to the air compressor 12 for compression, the obtained high-pressure air is cooled by the cooling device and condensed into liquid air, and finally is sent to the liquid air storage tank for storage. Specifically, when the power of the renewable energy power generation system is excessive enough to load the electrolysis unit, part of the power can be used for providing power for devices such as an air compressor, the outside air is subjected to liquidation treatment, liquid air is stored, and the liquid air is stored in a liquid air storage tank; when the renewable energy power generation system is insufficient in electric power and cannot fully bear the electrolytic unit, the liquid air in the liquid air storage tank is converted into gaseous air to perform energy conversion, the energy is converted into power of a generator to drive the generator to generate electricity, and then the electricity is used for water electrolysis reaction performed by the electrolytic unit.
Referring to fig. 2, the air separation unit 2 includes a high pressure rectifying tower 21, an expansion valve 22, and a low pressure rectifying tower 23; the high-pressure rectifying tower 21 is communicated with the liquid air energy storage unit 1, and the low-pressure rectifying tower 23 is communicated with the ammonia synthesis unit 4; wherein, the liquid air from the liquid air energy storage unit 1 is rectified by a high-pressure rectifying tower 21, then sent into an expansion valve 22 for boosting, finally sent into a low-pressure rectifying tower 23, and finally fractionated to obtain nitrogen. It should be understood that the rectification fractionation is to separate the chemical products from various mixed gases by different boiling points, and specifically, the fractionation separation and recovery collection of oxygen in liquid air can be performed simultaneously in the rectification process.
Referring to fig. 2, the ammonia synthesis unit 4 includes a first stage reactor 41, a second stage reactor 43 and a third stage reactor 45 which are sequentially connected to each other; the first stage reactor 41 is connected to the air separation unit 2 and the electrolysis unit 3, and receives nitrogen and hydrogen from both units to perform nitrogen synthesis reaction; the second stage reactor 43 and the third stage reactor 45 receive the mixed gas from the first stage reactor 41, and continue the nitrogen synthesis reaction and the mixed gas transfer. Specifically, ammonia synthesis is performed under conditions of high temperature and high pressure and a catalyst, and the reaction is exothermic. Specifically, the three reactors further increase the reaction time, so that the synthesis reaction can be more fully performed.
Referring to fig. 2, the ammonia synthesis unit 4 further comprises an ammonia separation device 47; the ammonia separation device 47 is disposed in communication with the third stage reactor 45, and receives the mixed gas after the synthesis reaction in the three reactors, and separates ammonia. It should be understood that the mixed gas contains a portion of unreacted hydrogen and oxygen and synthesized ammonia.
Referring to fig. 2, a third water heat exchanger 42 is disposed between the first stage reactor 41 and the second stage reactor 43, a second water heat exchanger 44 is disposed between the second stage reactor 43 and the third stage reactor 45, and a first water heat exchanger 46 is disposed at the outlet of the third stage reactor 45; the first water heat exchanger 46, the second water heat exchanger 44, and the third water heat exchanger 42 are disposed in heat exchange water communication, and the three water heat exchangers respectively absorb heat generated in the ammonia synthesis process and perform circulation transfer. Specifically, through a plurality of heat exchangers that set up, absorb the conversion to the heat that releases in the ammonia synthesis process, aqueous medium is introduced from first level water heat exchanger heat, and first water heat exchanger, second water heat exchanger and third water heat exchanger are passed through in proper order, and the gradual absorption is at each level the reaction heat that produces in the reactor to carry out heat transfer through aqueous medium.
Referring to fig. 2, the electrolysis unit 3 includes a solid oxide high temperature electrolysis tank 31, an oxygen compressor 34, and a hydrogen compressor 35; one end of the hydrogen compressor 35 is connected with the solid oxide high-temperature electrolytic tank 31, and the other end is connected with the first-stage reactor 41; the oxygen compressor 34 is provided with one end in communication with the solid oxide high temperature electrolytic tank 31 and the other end in communication with the first stage reactor 41. Specifically, the solid oxide high-temperature electrolytic tank is efficient and rapid in hydrogen production, and no hydrogen storage equipment is needed. More specifically, the solid oxide high-temperature electrolytic tank is subjected to hydrolysis reaction to obtain hydrogen and oxygen, the oxygen is recovered after being treated by an oxygen compressor, and the hydrogen enters a first-stage reactor after being treated by the hydrogen compressor and is subjected to synthesis reaction with nitrogen to generate ammonia.
Referring to fig. 2, the electrolysis unit 3 further includes a fourth hydrothermal exchanger 33 and a fifth hydrothermal exchanger 32; the fourth hydrothermal exchanger 33 is disposed between the hydrogen compressor 35 and the solid oxide high temperature electrolytic tank 31, and the fifth hydrothermal exchanger 32 is disposed between the oxygen compressor 34 and the solid oxide high temperature electrolytic tank 31; the fourth water heat exchanger 33 is disposed in heat exchange water communication with the third water heat exchanger 42, the fifth water heat exchanger 32 is disposed in heat exchange water communication with the fourth water heat exchanger 33, and the heat exchange water in the fifth water heat exchanger 32 is disposed in heat exchange water communication with the solid oxide high temperature electrolytic tank 31. Specifically, the aqueous medium (heat-exchanged water) from the third water heat exchanger 46 enters the fourth water heat exchanger 44 to further absorb heat carried in the hydrogen gas generated by the electrolysis reaction, then the aqueous medium continues to enter the fifth water heat exchanger 32 and absorbs heat carried in the oxygen gas generated by the electrolysis reaction, and then enters the solid oxide high temperature electrolytic tank 31, and since the aqueous medium absorbs heat by the five water heat exchangers, it can enter as water vapor when entering the solid oxide high temperature electrolytic tank 31. More specifically, the five hydrothermal exchangers are used for integrally utilizing the heat of the ammonia synthesis unit 4, so that the utilization of heat energy in the green ammonia synthesis process is further improved, and the overall conversion efficiency of the green electroconversion ammonia is further improved.
Referring to fig. 2, the liquid air energy storage unit 1 further includes a power generation system; the power generation system comprises a gasification heating device 15, a high-pressure turbine 16, a medium-pressure turbine 17, a low-pressure turbine 18 and a generator 19 which are sequentially communicated; the gasification heating device 15 is communicated with the liquid air storage tank 14, and the generator 19 is communicated with the electrolysis unit 2. Specifically, after the liquid air stored in the liquid air storage tank 14 is heated by the gasification heating device 15, the liquid air is converted into power of the generator 19 through the action of three turbines to drive the generator to generate electricity, and the electricity is applied to the electrolysis unit 2, especially when the electricity of the renewable energy power generation system 5 is insufficient to maintain the chemical reaction in the electrolysis unit 2.
In summary, the system for synthesizing the green ammonia based on liquid air energy storage and high-temperature electrolysis has the beneficial effects that: in the invention, a hydrogen storage tank is eliminated, the capacity of the electrolysis unit can be properly reduced, and the electrolysis unit and the synthetic ammonia unit can be designed to have the same or close capacity and can operate under constant load; the system can continuously and uninterruptedly run so as to realize high-efficiency production and heat integration of the system level; compared with the conventional electroammonia process (the efficiency is about 50%), the overall efficiency of the invention can be improved to more than 80%, and the process energy efficiency is obviously improved.
The invention discloses a method for synthesizing green ammonia based on liquid air energy storage and high-temperature electrolysis, which is characterized by comprising the following steps:
firstly, storing liquid air, namely storing the outside air in a liquid air form after the outside air is treated;
secondly, preparing nitrogen, and fractionating liquid air to obtain nitrogen;
preparing hydrogen, preparing hydrogen while preparing nitrogen, generating electricity through possible renewable energy sources, and then electrolyzing water vapor by using a solid oxide high-temperature electrolytic tank to obtain hydrogen;
fourthly, ammonia is prepared, and the nitrogen and the hydrogen are subjected to a synthetic reaction to obtain ammonia;
and fifthly, recycling heat, and recycling heat generated in the ammonia synthesis reaction process to a hydrogen preparation link for use while preparing ammonia.
Specifically, the preparation method of the invention is based on liquid air energy storage and high-temperature electrolysis for synthesizing the green ammonia: on one hand, the solid oxide high-temperature electrolytic tank is used for preparing hydrogen, so that the condition that the efficiency of an alkaline electrolytic tank and a proton exchange membrane electrolytic tank is low in the traditional preparation method is avoided; on the other hand, the heat of the exothermic reaction in the ammonia preparation process is recycled to the hydrogen production process, so that the utilization rate of heat energy in the green ammonia synthesis process is further improved.
It should be noted that in this document relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
Finally, it should be noted that: it is apparent that the above examples are only illustrative of the present invention and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.
Claims (9)
1. A system for synthesizing green ammonia based on liquid air energy storage and high temperature electrolysis, comprising:
the renewable energy power generation system is used for providing electric energy;
the liquid air energy storage unit is communicated with the renewable energy power generation system, receives the electric power of the renewable energy power generation system to treat the outside air and store electric energy in the form of liquid air, and can convert the liquid air into a gaseous form and convert the energy in the process into electric energy;
the air separation unit is communicated with the liquid air energy storage unit and receives the liquid air from the liquid air energy storage unit for separation treatment to obtain nitrogen;
the electrolysis unit is electrically communicated with the renewable energy power generation system and the liquid air energy storage unit, receives the electric power of the renewable energy power generation system to perform water electrolysis reaction to obtain hydrogen, and when the power supply of the renewable energy power generation system is insufficient, the electrolysis unit is driven by the electric power generated by the liquid conversion of the liquid air energy storage unit to continue the electrolysis reaction;
and the ammonia synthesis unit is communicated with the air separation unit and the electrolysis unit, receives the nitrogen from the air separation unit and the hydrogen from the electrolysis unit to perform ammonia synthesis, and simultaneously recovers and transmits heat generated in the reaction process to the electrolysis unit.
2. The system for synthesizing green ammonia based on liquid air energy storage and high-temperature electrolysis according to claim 1, wherein the liquid air energy storage unit comprises a filtering and drying device, an air compressor, a cooling device and a liquid air storage tank which are sequentially communicated; the filtering and drying device is used for receiving outside air, and the liquid air storage tank is communicated with the air separation unit.
3. The system for synthesizing green ammonia based on liquid air energy storage and high temperature electrolysis according to claim 1, wherein the air separation unit comprises a high pressure rectifying tower, an expansion valve and a low pressure rectifying tower; the high-pressure rectifying tower is communicated with the liquid air energy storage unit, and the low-pressure rectifying tower is communicated with the ammonia synthesis unit.
4. The system for synthesizing green ammonia based on liquid air energy storage and high temperature electrolysis according to claim 1, wherein the ammonia synthesis unit comprises a first-stage reactor, a second-stage reactor and a third-stage reactor which are sequentially communicated; the first-stage reactor is communicated with the air separation unit and the electrolysis unit and respectively receives nitrogen and hydrogen from the air separation unit and the electrolysis unit to carry out nitrogen synthesis reaction; and the second-stage reactor and the third-stage reactor receive the mixed gas from the first-stage reactor and continue to carry out nitrogen synthesis reaction and mixed gas delivery.
5. The system for synthesizing green ammonia based on liquid air energy storage and high temperature electrolysis according to claim 4, wherein the ammonia synthesis unit further comprises an ammonia separation device; the ammonia separation device is communicated with the third-stage reactor, receives the mixed gas after the synthesis reaction of the three reactors, and separates ammonia.
6. The system for synthesizing green ammonia based on liquid air energy storage and high temperature electrolysis according to claim 4 or 5, wherein a third water heat exchanger is arranged between the first stage reactor and the second stage reactor, a second water heat exchanger is arranged between the second stage reactor and the third stage reactor, and a first water heat exchanger is arranged at the outlet of the third stage reactor; the first water heat exchanger, the second water heat exchanger and the third water heat exchanger are communicated with each other by heat exchange water, and the heat generated in the ammonia synthesis process is absorbed by the three water heat exchangers respectively and is transferred in a circulating way.
7. The system for synthesizing green ammonia based on liquid air energy storage and high temperature electrolysis according to claim 6, wherein the electrolysis unit comprises a solid oxide high temperature electrolysis cell, an oxygen compressor and a hydrogen compressor; one end of the hydrogen compressor is connected with the solid oxide high-temperature electrolytic tank, and the other end of the hydrogen compressor is connected with the first-stage reactor; one end of the oxygen compressor is communicated with the solid oxide high-temperature electrolytic tank, and the other end of the oxygen compressor is communicated with the first-stage reactor.
8. The system for synthesizing green ammonia based on liquid air energy storage and high temperature electrolysis according to claim 7, wherein the electrolysis unit further comprises a fourth stage hydrothermal exchanger and a fifth stage hydrothermal exchanger; the fourth-stage hydrothermal exchanger is arranged between the hydrogen compressor and the solid oxide high-temperature electrolytic tank, and the fifth-stage hydrothermal exchanger is arranged between the oxygen compressor and the solid oxide high-temperature electrolytic tank; the fourth-stage water heat exchanger is communicated with the heat exchange water in the third water heat exchanger, the fifth-stage water heat exchanger is communicated with the heat exchange water in the fourth water heat exchanger, and the heat exchange water in the fifth water heat exchanger is communicated with the solid oxide high-temperature electrolytic tank.
9. The system for synthesizing ammonia based on liquid air energy storage and high temperature electrolysis according to claim 2, wherein the liquid air energy storage unit further comprises a power generation system; the power generation system comprises a gasification heating device, a high-pressure turbine, a medium-pressure turbine, a low-pressure turbine and a generator which are sequentially communicated; the gasification heating device is communicated with the liquid air storage tank, and the generator is communicated with the electrolysis unit.
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| CN117509671A (en) * | 2024-01-08 | 2024-02-06 | 华电曹妃甸重工装备有限公司 | System for dynamic synthesis of green ammonia by new energy hydrogen production and operation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117509671A (en) * | 2024-01-08 | 2024-02-06 | 华电曹妃甸重工装备有限公司 | System for dynamic synthesis of green ammonia by new energy hydrogen production and operation method thereof |
| CN117509671B (en) * | 2024-01-08 | 2024-03-22 | 华电曹妃甸重工装备有限公司 | System for dynamic synthesis of green ammonia by new energy hydrogen production and operation method thereof |
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