Hydrogen energy-based oxygen-enriched combustion low-carbonization system for coal-fired power plants

Abstract

The utility model relates to hydrogen energy carbon reduction technology field, and disclose a kind of coal-fired power plant oxygen-enriched combustion low carbonization system based on hydrogen energy, the system includes: combustion power generating unit and electrolytic water unit, the electrolytic water unit is used to deliver oxygen to coal-fired power plant;The system further includes: carbon dioxide capture unit, heat exchange unit, methanation unit, methane cracking unit and renewable energy power generating unit, the carbon dioxide capture unit is used to capture carbon dioxide in combustion power generating unit tail gas, the methanation unit is used to carry out methanation reaction to generate methane and water with carbon dioxide and hydrogen, the methane cracking unit is used to generate green graphite or carbon black such as carbon element and hydrogen with methane cracking reaction, and the renewable energy power generating unit is used to deliver renewable energy power generating unit's electric power to system.The utility model solves the problem of carbon dioxide capture and processing of combustion tail gas, realizes carbon element resource utilization, oxygen element recycling effect.

Description

Technical Field

[0001] This utility model belongs to the field of hydrogen energy carbon reduction technology, specifically relating to a hydrogen-based oxygen-enriched combustion low-carbon system for coal-fired power plants. Background Technology

[0002] As the "ballast" of my country's power supply, coal-fired power plants are facing increasingly important trends in energy efficiency improvement and low-carbon transformation under the backdrop of energy transition and dual-carbon goals. Oxygen-enriched combustion has become an effective control method to improve combustion efficiency and reduce emissions of combustible and toxic gases. Oxygen-enriched combustion refers to combustion using oxygen-containing gas with a higher oxygen content than air (20.947%). Oxygen is typically obtained from the air using air separation units, increasing system energy consumption and costs. Furthermore, the large amount of carbon dioxide emitted in the exhaust gas from oxygen-enriched combustion is a major source of carbon emissions from coal-fired power plants. Therefore, efficiently and cost-effectively solving the problems of oxygen source and carbon dioxide capture and treatment in oxygen-enriched combustion has become a key core technology for upgrading coal-fired power plants. Utility Model Content

[0003] To address the shortcomings of existing technologies, this utility model provides a hydrogen-based oxygen-enriched combustion low-carbon system for coal-fired power plants. By utilizing renewable energy electricity and off-peak electricity from coal-fired power plants to electrolyze water, hydrogen and oxygen are produced. The oxygen is fed to the combustion and power generation unit of the coal-fired power plant, and the exhaust gas is captured by a carbon dioxide capture unit and subsequently processed for resource recovery. This solves the problems of oxygen source and carbon dioxide capture and treatment of combustion exhaust gas in oxygen-enriched combustion, and achieves the effects of carbon resource utilization and hydrogen and oxygen recycling.

[0004] To achieve the aforementioned goals of carbon resource utilization and oxygen recycling, this utility model provides the following technical solution: a hydrogen-based oxygen-enriched combustion low-carbon system for coal-fired power plants, the system comprising: a combustion power generation unit and a water electrolysis unit, wherein the oxygen outlet of the water electrolysis unit is connected to the oxygen inlet of the coal-fired power plant via an oxygen pipeline, and the power output terminal of the combustion power generation unit is connected to the power input terminal of the water electrolysis unit; the combustion power generation unit supplies power to the water electrolysis unit, and the water electrolysis unit supplies oxygen to the combustion power generation unit;

[0005] The system further includes a carbon dioxide capture unit and a heat exchange unit. The exhaust gas inlet of the heat exchange unit is connected to the exhaust gas outlet of the combustion power generation unit through a first power plant combustion exhaust gas pipeline, and the exhaust gas outlet of the heat exchange unit is connected to the exhaust gas inlet of the carbon dioxide capture unit through a second power plant combustion exhaust gas pipeline. The steam outlet of the heat exchange unit is connected to the heat working fluid inlet of the water electrolysis unit through a steam pipeline.

[0006] Furthermore, the system also includes: a methanation unit, wherein the carbon dioxide inlet of the methanation unit is connected to the carbon dioxide outlet of the carbon dioxide capture unit via a carbon dioxide pipeline; the water vapor outlet of the methanation unit is connected to the water vapor inlet of the heat exchange unit via a first water vapor pipeline; and the hydrogen inlet of the methanation unit is connected to the hydrogen outlet of the water electrolysis unit via a second hydrogen pipeline.

[0007] Furthermore, the system further includes: a methane cracking unit, wherein the methane inlet of the methane cracking unit is connected to the methane outlet of the methanation unit via a methane pipeline, and the hydrogen outlet of the methane cracking unit is connected to the hydrogen inlet of the methanation unit via a first hydrogen pipeline; and the heat exchange unit's working fluid outlet is connected to the working fluid inlet of the methane cracking unit via a heat pipeline.

[0008] Furthermore, the system also includes a renewable energy power generation unit, the power output terminal of which is connected to the power input terminal of the water electrolysis unit.

[0009] Furthermore, the combustion power generation unit includes a boiler combustion module and a steam power generation module. The oxygen pipeline is connected to the oxygen inlet of the boiler combustion module, the first power plant combustion exhaust gas pipeline is connected to the exhaust gas outlet of the boiler combustion module, and the steam inlet of the steam power generation module is connected to the steam outlet of the boiler combustion module.

[0010] Furthermore, the carbon dioxide capture unit includes an absorption tower and a regeneration tower connected to the top of the absorption tower, and the second power plant combustion exhaust gas pipeline is connected to the bottom of the absorption tower.

[0011] A circulating pump is connected to the corresponding inlet and outlet of the absorption tower and the regeneration tower through pipelines, and is used to realize the circulation of the absorbent between the absorption tower and the regeneration tower.

[0012] The carbon dioxide capture unit further includes a heat exchanger and a compressor. The carbon dioxide inlet of the heat exchanger is connected to the carbon dioxide outlet of the regeneration tower, and the carbon dioxide outlet of the heat exchanger is connected to the compressor.

[0013] Furthermore, the methanation unit includes a methanation reactor and a PSA pressure swing adsorption device. The carbon dioxide pipeline and the second hydrogen pipeline are both connected to the corresponding inlets of the methanation reactor. The inlet of the PSA pressure swing adsorption device is connected to the product outlet of the methanation reactor. The corresponding outlets of the PSA pressure swing adsorption device are connected to the methane pipeline and the first water vapor pipeline.

[0014] Furthermore, the methane cracking unit includes a high-temperature reactor and a cyclone separator, wherein the methane inlet of the high-temperature reactor is connected to a methane pipeline, and the carbon material outlet of the high-temperature reactor is connected to the cyclone separator.

[0015] Furthermore, the methane cracking unit also includes a bag filter, the inlet of which is connected to the exhaust gas outlet of the cyclone separator.

[0016] Compared with existing technologies, this utility model provides a hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants, which has the following beneficial effects:

[0017] First, this utility model solves the problems of oxygen source and carbon dioxide treatment in oxygen-enriched combustion of coal-fired power plants, eliminating the need for additional air separation equipment and realizing the clean transformation of traditional coal-fired power plants, resulting in significant economic and environmental benefits.

[0018] Secondly, this new process enables the stepwise decomposition of carbon dioxide consumption in biomass or off-peak electricity, producing carbon black or other elemental carbon and oxygen, which conforms to the principle of atom economy and realizes the resource utilization of carbon dioxide in coal-fired power plant tail gas and the co-production of high-value-added carbon products. Furthermore, the three sub-reactions can also reuse the heat carried by the tail gas and the heat released by the methanation reaction through heat exchange, reducing overall energy efficiency. Attached Figure Description

[0019] Figure 1 is a simplified composition diagram of an oxygen-enriched combustion low-carbon system for a hydrogen-powered coal-fired power plant.

[0020] Figure 2 shows the composition of a hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants.

[0021] Figure 3 shows the composition of the combustion power generation unit in a hydrogen-based oxygen-enriched combustion low-carbon system for coal-fired power plants.

[0022] Figure 4 shows the composition of the carbon dioxide capture unit in the oxygen-enriched combustion low-carbonization system of a hydrogen-based coal-fired power plant.

[0023] Figure 5 shows the composition of the methanation unit in a hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants.

[0024] Figure 6 shows the composition of the methane cracking unit in a hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants.

[0025] In the diagram: 1. Combustion power generation unit; 2. Carbon dioxide capture unit; 3. Methanation unit; 4. Methane cracking unit; 5. Water electrolysis unit; 6. Renewable energy power generation unit; 7. Heat exchange unit; 11. Boiler combustion module; 12. Steam power generation module; 21. Absorption tower; 22. Regeneration tower; 23. Circulating pump; 24. Heat exchanger; 25. Compressor; 31. Reactor; 32. PSA pressure swing adsorption device; 41. High-temperature reactor; 42. Cyclone separator; 43. Bag filter; 101. Combustion exhaust gas pipeline of the first power plant; 102. Combustion exhaust gas pipeline of the second power plant; 103. Carbon dioxide pipeline; 201. Methane pipeline; 301. First hydrogen pipeline; 302. Second hydrogen pipeline; 501. First steam pipeline; 502. Second steam pipeline; 701. 1. Heating pipelines; 801. Oxygen pipelines. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] A hydrogen-based oxygen-enriched combustion low-carbon system for coal-fired power plants, as shown in Figure 1, includes a combustion power generation unit 1 and a water electrolysis unit 5. The oxygen outlet of the water electrolysis unit 5 is connected to the oxygen inlet of the coal-fired power plant 1 via an oxygen pipeline 801. The power output terminal of the combustion power generation unit 1 is connected to the power input terminal of the water electrolysis unit 5. The combustion power generation unit 1 supplies power to the water electrolysis unit 5, and the water electrolysis unit 5 supplies oxygen to the combustion power generation unit 1. The main component of the water electrolysis unit 5, the electrolyzer, can be a technologically mature alkaline electrolyzer or a PEM electrolyzer, with the PEM electrolyzer being the optimal choice. This is because it has better adaptability to fluctuations in renewable energy and meets the requirements for pure water as a raw material.

[0028] The system further includes a carbon dioxide capture unit 2 and a heat exchange unit 7. The exhaust gas inlet of the heat exchange unit 7 is connected to the exhaust gas outlet of the combustion power generation unit 1 through a first power plant combustion exhaust gas pipeline 101, and the exhaust gas outlet of the heat exchange unit 7 is connected to the exhaust gas inlet of the carbon dioxide capture unit 2 through a second power plant combustion exhaust gas pipeline 102. The steam outlet of the heat exchange unit 7 is connected to the working fluid inlet of the water electrolysis unit 5 through a steam pipeline.

[0029] As a preferred embodiment, referring to Figure 2, the system further includes: a methanation unit.

[0030] 3 and methane cracking unit 4, wherein the carbon dioxide inlet of the methanation unit 3 is connected to the carbon dioxide outlet of the carbon dioxide capture unit 2 through carbon dioxide pipeline 103; the steam outlet of the methanation unit 3 is connected to the steam inlet of the heat exchange unit 7 through a first steam pipeline 501; and the hydrogen inlet of the methanation unit 3 is connected to the hydrogen outlet of the water electrolysis unit 5 through a second hydrogen pipeline 302.

[0031] The methane inlet of the methane cracking unit 4 is connected to the methane outlet of the methanation unit 3 via a methane pipeline 201, and the hydrogen outlet of the methane cracking unit 4 is connected to the hydrogen inlet of the methanation unit 3 via a first hydrogen pipeline 301; furthermore, the heat exchange unit 7 is connected to the heat exchange unit 4 via a heat exchange pipeline 701, for supplying heat to the methane cracking unit 4 through the heat exchange unit 7.

[0032] As a preferred embodiment, please refer to Figure 1. The system further includes a renewable energy power generation unit 6, the power output terminal of which is connected to the power input terminal of the water electrolysis unit 5, for supplying power from the renewable energy power generation unit 6 to the water electrolysis unit 5. The renewable energy power generation unit 6 adopts mature wind power generation or photovoltaic power generation technology, taking into account the characteristics of local resources.

[0033] As a preferred embodiment, please refer to Figure 3. The combustion power generation unit 1 includes a boiler combustion module 11 and a steam power generation module 12. The oxygen pipeline 801 is connected to the oxygen inlet of the boiler combustion module 11. The first power plant combustion exhaust gas pipeline 101 is connected to the exhaust gas outlet of the boiler combustion module 11. The steam inlet of the steam power generation module 12 is connected to the steam outlet of the boiler combustion module 11. The water electrolysis unit 5 electrolyzes to produce hydrogen and oxygen. Waste heat is recovered by the heat exchange unit 7 and enters the pipeline. The waste heat temperature is generally in the range of 60-90℃. Oxygen enters the boiler combustion module 11 through the pipeline, and oxygen-enriched combustion produces a large amount of high-temperature steam (16-30MPa, 540-600℃), which enters the steam power generation module 12 to generate electricity. Hydrogen enters the methanation unit 3 through the pipeline.

[0034] As a preferred embodiment, please refer to Figure 4. The carbon dioxide capture unit 2 includes: an absorption tower 21 and a regeneration tower 22 connected to the top of the absorption tower 21. The second power plant combustion exhaust gas pipeline 102 is connected to the bottom of the absorption tower.

[0035] A circulation pump 23 is connected to the absorption tower 21 and the regeneration tower 22 via pipelines to realize the circulation of the absorbent between the absorption tower 21 and the regeneration tower 22.

[0036] The oxygen-enriched combustion exhaust gas from the steam power generation module 12 is typically maintained at 300-500℃, with a carbon dioxide concentration between 70% and 90%. It first recovers heat through heat exchange unit 7, then enters the absorption tower 21 in the carbon dioxide capture unit 2, where it comes into countercurrent contact with the lean amine solution, absorbing the carbon dioxide. Once saturated with carbon dioxide, the lean amine solution becomes rich amine solution and enters the regeneration tower 22. Inside the regeneration tower 22, the system is heated and depressurized to release carbon dioxide. The carbon dioxide is then discharged through heat exchanger 24 and compressor 25 into the methanation unit 3. The regenerated lean amine solution, after the release of carbon dioxide, is driven by circulation pump 23 from the bottom of the regeneration tower to the top of the absorption tower, forming a continuous circulation throughout the system.

[0037] The carbon dioxide capture unit 2 further includes a heat exchanger 24 and a compressor 25. The carbon dioxide inlet of the heat exchanger 24 is connected to the carbon dioxide outlet of the regeneration tower 22, and the carbon dioxide outlet of the heat exchanger 24 is connected to the compressor 25, which is used to compress carbon dioxide and input it into the methanation unit 3 through the carbon dioxide pipeline.

[0038] As a preferred embodiment, referring to Figure 5, the methanation unit 3 includes: a methanation reactor 31 and a PSA pressure swing adsorption device 32. The carbon dioxide pipeline 103 and the second hydrogen pipeline 302 are both connected to the corresponding inlets of the methanation reactor 31. The inlet of the PSA pressure swing adsorption device 32 is connected to the product outlet of the methanation reactor 31 and is used to remove the methane produced by the methanation reactor 31. The corresponding outlets of the PSA pressure swing adsorption device 32 are all connected to the methane pipeline 201 and the first water vapor pipeline 501.

[0039] Hydrogen and carbon dioxide enter reactor 31 of methanation unit 3, where a methanation reaction occurs under the action of a catalyst to synthesize methane and water vapor. After heat recovery and exchange in heat exchange unit 7, the methane enters PSA adsorption unit 32 to separate high-purity methane. The separated water enters the water electrolysis unit as a feedstock for water electrolysis.

[0040] As a preferred embodiment, please refer to Figure 6. The methane cracking unit 3 includes: a high-temperature reactor 41, a cyclone separator 42, and a bag filter 43. The methane inlet of the high-temperature reactor 41 is connected to the methane pipeline 201, and the carbon material outlet of the high-temperature reactor 41 is connected to the cyclone separator 42 for separating the carbon material from the reaction tail gas. The inlet of the bag filter 43 is connected to the tail gas outlet of the cyclone separator 42 for further separating the carbon material obtained by the high-temperature reactor 41.

[0041] Methane enters the high-temperature reactor 41 in the methane cracking unit 4 at a temperature of 1000-1200℃. To reduce side reactions, the residence time of methane in the high-temperature reactor 41 is typically 0.1-0.5 seconds, allowing it to pass through rapidly and form high-temperature dust-laden gas. This high-temperature dust-laden gas exits the high-temperature reactor 41 and enters the cyclone separator 42, where coarse carbon black is separated and collected. The remaining gas enters a bag filter, where fine carbon black is intercepted by the filter bags. The final carbon black product is cooled and packaged. The filtered gas is then recirculated through pipelines to the reactor 31 in the methanation unit 3.

[0042] The operating principle of this invention is as follows: The renewable energy power generation unit uses wind or photovoltaic power to generate electricity, which is then distributed to the water electrolysis unit via a power transmission and distribution device. The water electrolysis unit undergoes an electrolysis reaction, producing oxygen at the anode, which is then transported through pipelines to the coal-fired power plant combustion power generation unit. Hydrogen is produced at the cathode and transported through pipelines to the methanation unit. The coal-fired power plant combustion power generation unit undergoes oxygen-enriched combustion, producing combustion exhaust gas rich in carbon dioxide, which passes through a carbon dioxide capture unit. The carbon dioxide is captured, purified, and released as pure carbon dioxide, which then passes through the methanation unit. In the methanation unit, carbon dioxide and hydrogen undergo a methanation reaction to produce methane and water, releasing heat. The methane then passes through a methane cracking unit, where it undergoes a methane cracking reaction to produce green graphite or carbon black and other carbon elements, as well as hydrogen. The hydrogen is returned to the methanation unit. The water produced in the methanation reaction has its heat recovered by a heat exchange unit and passes through the water electrolysis unit as a raw material for water electrolysis.

[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, the phrase "comprising one..." The definition of a particular element does not preclude the presence of other identical elements in a process, method, article, or apparatus that includes the element.

[0044] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants, characterized in that: The system includes a combustion power generation unit (1) and an electrolysis water unit (5). The oxygen outlet of the electrolysis water unit (5) is connected to the oxygen inlet of the coal-fired power plant through an oxygen pipeline (801). The power output terminal of the combustion power generation unit (1) is connected to the power input terminal of the electrolysis water unit (5). The system further includes a carbon dioxide capture unit (2) and a heat exchange unit (7). The exhaust gas inlet of the heat exchange unit (7) is connected to the exhaust gas outlet of the combustion power generation unit (1) through a first power plant combustion exhaust gas pipeline (101). The exhaust gas outlet of the heat exchange unit (7) is connected to the exhaust gas inlet of the carbon dioxide capture unit (2) through a second power plant combustion exhaust gas pipeline (102). The steam outlet of the heat exchange unit (7) is connected to the heat working medium inlet of the water electrolysis unit (5) through a steam pipeline.

2. The hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants according to claim 1, characterized in that: The system further includes: a methanation unit (3), wherein the carbon dioxide inlet of the methanation unit (3) is connected to the carbon dioxide outlet of the carbon dioxide capture unit (2) through a carbon dioxide pipeline (103); the water vapor outlet of the methanation unit (3) is connected to the water vapor inlet of the heat exchange unit (7) through a first water vapor pipeline (501); and the hydrogen inlet of the methanation unit (3) is connected to the hydrogen outlet of the water electrolysis unit (5) through a second hydrogen pipeline (302).

3. The hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants according to claim 2, characterized in that: The system further includes: a methane cracking unit (4), the methane inlet of the methane cracking unit (4) is connected to the methane outlet of the methanation unit (3) through a methane pipeline (201), the hydrogen outlet of the methane cracking unit (4) is connected to the hydrogen inlet of the methanation unit (3) through a first hydrogen pipeline (301); the heat exchange unit (7) heat working fluid outlet is connected to the heat working fluid inlet of the methane cracking unit (4) through a heat pipeline (701).

4. The hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants according to claim 2, characterized in that: The system also includes a renewable energy power generation unit (6), the power output terminal of which is connected to the power input terminal of the water electrolysis unit (5).

5. The hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants according to claim 1, characterized in that: The combustion power generation unit (1) includes a boiler combustion module (11) and a steam power generation module (12). The oxygen pipeline (801) is connected to the oxygen inlet of the boiler combustion module (11), the first power plant combustion exhaust pipeline (101) is connected to the exhaust outlet of the boiler combustion module (11), and the steam inlet of the steam power generation module (12) is connected to the steam outlet of the boiler combustion module (11).

6. The hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants according to claim 1, characterized in that: The carbon dioxide capture unit (2) includes: an absorption tower (21) and a regeneration tower (22) connected to the top of the absorption tower (21), and the second power plant combustion exhaust pipe (102) is connected to the bottom of the absorption tower; The circulating pump (23) is connected to the absorption tower (21) and the regeneration tower (22) through pipelines, with corresponding inlet and outlet connections; The carbon dioxide capture unit (2) further includes a heat exchanger (24) and a compressor (25). The carbon dioxide inlet of the heat exchanger (24) is connected to the carbon dioxide outlet of the regeneration tower (22), and the carbon dioxide outlet of the heat exchanger (24) is connected to the compressor (25).

7. The hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants according to claim 2, characterized in that: The methanation unit (3) includes a methanation reactor (31) and a PSA pressure swing adsorption device (32). The carbon dioxide pipeline (103) and the second hydrogen pipeline (302) are connected to the corresponding inlets of the methanation reactor (31). The inlet of the PSA pressure swing adsorption device (32) is connected to the product outlet of the methanation reactor (31). The corresponding outlets of the PSA pressure swing adsorption device (32) are connected to the methane pipeline (201) and the first water vapor pipeline (501).

8. The hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants according to claim 3, characterized in that: The methane cracking unit (4) includes a high-temperature reactor (41) and a cyclone separator (42). The methane inlet of the high-temperature reactor (41) is connected to the methane pipeline (201), and the carbon material outlet of the high-temperature reactor (41) is connected to the cyclone separator (42).

9. The hydrogen-based oxygen-enriched combustion low-carbonization system for coal-fired power plants according to claim 8, characterized in that: The methane cracking unit (4) further includes a bag filter (43), the inlet of which is connected to the tail gas outlet of the cyclone separator (42).

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