Power station boiler blending combustion biomass fuel coupling chemical looping combustion system and method

Abstract

The invention relates to the technical field of biomass fuel, in particular to a power station boiler blending combustion biomass fuel coupling chemical looping combustion system and method.The power station boiler blending combustion biomass fuel coupling chemical looping combustion system comprises a water electrolysis device, the water electrolysis device is connected with a fuel reactor and a second gas mixer, and the fuel reactor is connected with an air reactor; the first gas mixer is connected with the air reactor; a boiler body; the biomass crusher is connected with the boiler body, and the biomass crusher is connected with the air reactor; the boiler body is connected with the first gas mixer, oxygen generated by electrolyzing water through a renewable energy source can serve as a chemical product to be recycled; and the biomass can also be mixed with air to form oxygen-enriched over fire air, so that the combustion efficiency of the boiler during mixed combustion of the biomass is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass fuels, and in particular to a system and method for co-firing biomass fuels in a power plant boiler coupled with chemical-looping combustion. Background Art

[0002] Under the urgent situation of global energy transformation and environmental protection, the upgrade of power plant boiler combustion technology is extremely urgent. For a long time, traditional power plant boilers have highly relied on fossil fuels. This mode not only accelerates the consumption of non-renewable resources but also causes a series of severe environmental problems. During the combustion process, a large amount of pollutants such as carbon dioxide, nitrogen oxides, and particulate matter are discharged into the atmosphere, posing a serious threat to global climate stability and air quality, and exacerbating environmental problems such as the greenhouse effect and acid rain.

[0003] As a green and renewable energy source, biomass fuels provide a new path to solve the energy and environmental dilemmas. It has a wide range of sources, including agricultural and forestry waste, energy crops, etc. Compared with fossil fuels, biomass fuels have a lower carbon content and can almost achieve net-zero carbon dioxide emissions during the combustion process, which is of great significance for reducing carbon emissions and mitigating climate change. However, there are inherent defects in the direct combustion of biomass fuels, with poor combustion efficiency and large losses during the energy conversion and utilization process, which limit its large-scale and efficient application.

[0004] As an emerging combustion method, chemical-looping combustion technology has attracted much attention in recent years. This technology realizes the separated combustion of fuel and air by means of the cyclic flow of oxygen carriers between the fuel reactor and the air reactor. This unique mechanism greatly improves the combustion efficiency and effectively reduces the generation of nitrogen oxides, demonstrating excellent energy-saving and emission-reduction potential.

[0005] Although biomass fuels and chemical-looping combustion technology each have obvious advantages, the current systems and methods for efficiently coupling the two in power plant boilers are still in the exploration stage, lacking mature and reliable technical solutions to fully exploit the synergistic potential.

[0006] Therefore, a system and method for co-firing biomass fuels in a power plant boiler coupled with chemical-looping combustion are proposed. Through innovative system design and method optimization, it aims to achieve the efficient and clean combustion of biomass fuels in power plant boilers, comprehensively improve energy utilization efficiency, significantly reduce pollutant emissions, and promote the power plant boiler combustion technology to make great strides towards the green and sustainable direction. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is: how to efficiently couple biomass fuels with chemical-looping combustion technology in a power plant boiler.

[0008] The above technical problems are solved by the following technical solutions: The present invention provides a power plant boiler co-firing biomass fuel coupled with chemical looping combustion system, including,

[0009] An electrolyzer, a fuel reactor and a second gas mixer are connected to the electrolyzer, and an air reactor is connected to the fuel reactor;

[0010] A first gas mixer, the first gas mixer is connected to the air reactor;

[0011] A boiler body;

[0012] A biomass crusher, the biomass crusher is connected to the boiler body, and the biomass crusher is connected to the air reactor;

[0013] The boiler body is connected to the first gas mixer.

[0014] In a preferred embodiment of the power plant boiler co-firing biomass fuel coupled with chemical looping combustion system of the present invention: An oxygen storage tank and a hydrogen storage tank are further included;

[0015] The oxygen storage tank and the hydrogen storage tank are connected to the electrolyzer;

[0016] The oxygen storage tank is used to store the generated oxygen;

[0017] The hydrogen storage tank is used to store the generated hydrogen.

[0018] In a preferred embodiment of the power plant boiler co-firing biomass fuel coupled with chemical looping combustion system of the present invention: A biomass nozzle, a pulverized coal nozzle and an overfire air nozzle are sequentially arranged on the boiler body from bottom to top;

[0019] The biomass nozzle is connected to the biomass crusher;

[0020] The second gas mixer is connected to the overfire air nozzle.

[0021] In a preferred embodiment of the power plant boiler co-firing biomass fuel coupled with chemical looping combustion system of the present invention: A condenser is connected to the fuel reactor, and a water storage tank is connected to the condenser.

[0022] In a preferred embodiment of the power plant boiler co-firing biomass fuel coupled with chemical looping combustion system of the present invention: A first induced draft fan and a first forced draft fan are provided on the first gas mixer;

[0023] The first induced draft fan is connected to the boiler body.

[0024] In a preferred embodiment of the system for co-firing biomass fuel and coupling chemical-looping combustion in a power station boiler according to the present invention: an air preheater is provided on the boiler body, and a second air blower is connected to the air preheater.

[0025] In a preferred embodiment of the system for co-firing biomass fuel and coupling chemical-looping combustion in a power station boiler according to the present invention: a dust collector is connected to the air preheater, a second induced draft fan is connected to the dust collector, and the dust collector is connected to a chimney through the second induced draft fan.

[0026] The present invention also provides a method for co-firing biomass fuel and coupling chemical-looping combustion in a power station boiler, which is applied to the system for co-firing biomass fuel and coupling chemical-looping combustion in a power station boiler, and includes,

[0027] Electrolyzing water through an electrolyzer.

[0028] Feeding the products generated by electrolyzing water into a fuel reactor and a second gas mixer respectively.

[0029] Using the high-temperature flue gas and air mixture in the flue to transport the biomass fuel powder generated by the biomass crusher to the biomass nozzle.

[0030] The second air blower feeds primary air, secondary air and overfire air into the air preheater for preheating.

[0031] The flue gas generated by the combustion of the boiler body can be discharged after dust removal in the dust collector, passing through the induced draft fan and the chimney.

[0032] In a preferred embodiment of the method for co-firing biomass fuel and coupling chemical-looping combustion in a power station boiler according to the present invention: hydrogen in the hydrogen storage tank is fed into the fuel reactor for reaction, reducing the oxide carrier to a metal carrier and generating water, while the metal carrier in the air reactor undergoes an oxidation reaction with air to generate metal oxides and release a large amount of heat.

[0033] Part of the oxygen in the oxygen storage tank is collected as a chemical product, and the other part is mixed with air in the second gas mixer to obtain oxygen-enriched overfire air, which is finally fed into the furnace through the overfire air nozzle for combustion.

[0034] In a preferred embodiment of the method for co-firing biomass fuel and coupling chemical-looping combustion in a power station boiler according to the present invention: using the first induced draft fan to introduce the high-temperature flue gas in the flue into the first gas mixer to mix with the air fed by the first air blower, and the formed two-medium mixed gas is fed into the air reactor for heat exchange, and using the large amount of heat released in chemical-looping combustion to preheat the two-medium mixed gas.

[0035] Using the preheated two-medium mixed gas, the biomass fuel powder generated by the biomass crusher is transported to the biomass nozzle in a direct blowing manner.

[0036] The beneficial effects of the present invention are as follows: The oxygen generated by electrolyzing water using renewable energy can not only be reused as a chemical product, but also be mixed with air to form oxygen-enriched burnout air, thereby improving the boiler combustion efficiency during co-firing of biomass. The energy that cannot be consumed generated by renewable energy is stored as hydrogen through electrolyzing water, and then the energy is released through chemical-looping combustion, which only produces water and no other pollutants. Moreover, compared with traditional hydrogen combustion for energy release, chemical-looping combustion has higher safety. The flue gas and external air are used to form a two-medium drying gas, which is preheated by releasing heat through the chemical-looping combustion system, and then the biomass powder is transported and dried, and the flow rate and temperature of the drying gas can be flexibly adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present invention and do not limit the present invention.

[0038] Figure 1 It shows a schematic diagram of the overall structure of a power plant boiler co-firing biomass fuel coupled with a chemical-looping combustion system.

[0039] In the figure: 1. Electrolyzer; 2. Oxygen storage tank; 3. Hydrogen storage tank; 4. Air reactor; 5. Fuel reactor; 6. First induced draft fan; 7. First forced draft fan; 8. First gas mixer; 9. Biomass crusher; 10. Condenser; 11. Water storage tank; 12. Second gas mixer; 13. Biomass nozzle; 14. Pulverized coal nozzle; 15. Burnout air nozzle; 16. Second forced draft fan; 17. Air preheater; 18. Dust collector; 19. Second induced draft fan; 20. Chimney; 21. Boiler body. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below in conjunction with the specific embodiments and the drawings.

[0041] The terms used in the present invention are those general terms that are currently widely used in the art in consideration of the functions of the present invention, but these terms can change according to the intentions of those of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms can be selected by the applicant, and in this case, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but based on the meanings of the terms and the overall description of the present invention.

[0042] Refer to Figure 1, this embodiment provides a power plant boiler co-firing biomass fuel coupled with chemical looping combustion system, including,

[0043] An electrolyzer 1, a fuel reactor 5 and a second gas mixer 12 are connected to the electrolyzer 1, and an air reactor 4 is connected to the fuel reactor 5;

[0044] A first gas mixer 8, the first gas mixer 8 is connected to the air reactor 4;

[0045] A boiler body 21;

[0046] A biomass crusher 9, the biomass crusher 9 is connected to the boiler body 21, and the biomass crusher 9 is connected to the air reactor 4;

[0047] The boiler body 21 is connected to the first gas mixer 8.

[0048] It also includes an oxygen storage tank 2 and a hydrogen storage tank 3;

[0049] The oxygen storage tank 2 and the hydrogen storage tank 3 are connected to the electrolyzer 1;

[0050] The oxygen storage tank 2 is used to store the generated oxygen;

[0051] The hydrogen storage tank 3 is used to store the generated hydrogen.

[0052] The boiler body 21 is successively provided with a biomass nozzle 13, a pulverized coal nozzle 14, and an overfire air nozzle 15 from bottom to top;

[0053] The biomass nozzle 13 is connected to the biomass crusher 9;

[0054] The second gas mixer 12 is connected to the overfire air nozzle 15.

[0055] A condenser 10 is connected to the fuel reactor 5, and a water storage tank 11 is connected to the condenser 10.

[0056] The first gas mixer 8 is provided with a first induced draft fan 6 and a first forced draft fan 7;

[0057] The first induced draft fan 6 is connected to the boiler body 21.

[0058] The boiler body 21 is provided with an air preheater 17, and a second forced draft fan 16 is connected to the air preheater 17.

[0059] A dust collector 18 is connected to the air preheater 17, a second induced draft fan 19 is connected to the dust collector 18, and the dust collector 18 is connected to a chimney 20 through the second induced draft fan 19.

[0060] In the present invention, redundant power generation generated by renewable energy power generation that cannot be absorbed by the power grid is used to carry out the electrolysis reaction in the electrolysis water device 1, and the generated oxygen and hydrogen are respectively introduced into the oxygen storage device 2 and the hydrogen storage device 3 for storage. The oxygen storage device 2 is connected to the second gas mixer 12, and after being mixed with the burnout air, oxygen-enriched burnout air is obtained, and then is sent into the furnace through the burnout air nozzle 15 for combustion. The hydrogen storage device 3 is connected to the fuel reactor 5, the generated water is introduced into the condenser 10 for condensation, and the finally obtained water is collected in the water storage tank 11. The outlets of the first induced draft fan 6 and the first forced draft fan 7 are both connected to the first gas mixer 8, and the high-temperature flue gas and the outside air are respectively introduced into the first gas mixer 8 for mixing; the outlet of the first gas mixer 8 is connected to the air reactor 4, and a large amount of heat released by the chemical looping combustion reaction is used to preheat the mixed gas, and then the mixed gas is used to transport the biomass powder generated by the biomass crusher 9 to the biomass nozzle 13 and finally enter the furnace for combustion. In the main combustion zone, the biomass nozzle 13 is arranged below the pulverized coal nozzle 14 to increase the residence time of biomass combustion and avoid clogging the downstream flue gas desulfurization equipment, etc. The second forced draft fan 16 sends the primary air, secondary air and burnout air into the air preheater 17 for preheating. The flue gas generated by the combustion of the boiler body 21 can be discharged after dust removal in the dust collector 18, through the second induced draft fan 19 and the chimney 20.

[0061] Referring to Figure 1 , this embodiment provides a method for co-firing biomass fuel and coupling chemical looping combustion in a power station boiler, which is applied to a system for co-firing biomass fuel and coupling chemical looping combustion in a power station boiler, including

[0062] Carry out electrolysis of water through the electrolysis water device 1; use the redundant power generation of wind power generation and photovoltaic power generation to carry out electrolysis of water in the electrolysis water device 1, and the generated oxygen and hydrogen are respectively stored in the oxygen storage device 2 and the hydrogen storage device 3.

[0063] Respectively introduce the products generated by electrolysis of water into the fuel reactor 5 and the second gas mixer 12;

[0064] The hydrogen in the hydrogen storage device 3 is introduced into the fuel reactor 5 for reaction, reducing the oxide carrier to a metal carrier and generating water, while the metal carrier in the air reactor 4 undergoes an oxidation reaction with air to generate metal oxides and release a large amount of heat;

[0065] Part of the water generated in the fuel reactor 5 is introduced into the condenser 10 for condensation, and the obtained water is collected in the water storage tank 11;

[0066] Use the high-temperature flue gas and air mixed gas in the flue to transport the biomass fuel powder generated by the biomass crusher 9 to the biomass nozzle 13;

[0067] The high-temperature flue gas in the flue is introduced into the first gas mixer 8 by the first induced draft fan 6 and mixed with the air sent by the first forced draft fan 7. The formed two-medium mixed gas is sent to the air reactor 4 for heat exchange, and a large amount of heat released in chemical-looping combustion is used to preheat the two-medium mixed gas.

[0068] Using the preheated two-medium mixed gas, the biomass fuel powder produced by the biomass crusher 9 is transported to the biomass nozzle 13 in a direct-blowing manner. During this period, the high-temperature two-medium mixed gas can dry the biomass fuel.

[0069] Part of the oxygen in the oxygen storage tank 2 is collected as a chemical product, and the other part is mixed with air in the second gas mixer 12 to obtain oxygen-rich burnout air, which is finally sent into the furnace through the burnout air nozzle 15 for combustion.

[0070] The second forced draft fan 16 sends primary air, secondary air, and burnout air into the air preheater 17 for preheating.

[0071] The flue gas generated by the combustion of the boiler body 21 can be dust-removed in the dust collector 18 and then discharged through the second induced draft fan 19 and the chimney 20.

[0072] Beneficial effects:

[0073] Using the furnace flue gas and external air to form a two-medium drying gas, preheating through the heat released by the chemical-looping combustion system, and then transporting and drying the biomass powder, the flow rate and temperature of the drying gas can be flexibly adjusted.

[0074] The oxygen concentration of the two-medium mixed gas coupled with the furnace flue gas is lower than that of air, which can avoid the occurrence of biomass deflagration in the pipe.

[0075] The biomass fuel nozzle is arranged at the lowest-layer burner, which can increase the residence time of the biomass fuel, enable components such as fibers to be fully burned, and avoid blocking subsequent desulfurization and other equipment.

[0076] The water generated by chemical-looping combustion can be collected by condensation to obtain a large amount of high-purity condensed water, which is used as boiler make-up water.

[0077] When the biomass feed changes or the moisture content of the biomass material fluctuates greatly, the characteristics of the two-medium drying gas can be used for dynamic adjustment to enable the system to operate stably.

[0078] The oxygen generated by electrolyzing water using renewable energy can not only be reused as a chemical product; it can also be mixed with air to form oxygen-rich burnout air, thereby improving the boiler combustion efficiency during biomass co-combustion.

[0079] The energy that cannot be consumed generated by renewable energy is stored as hydrogen through electrolyzed water, and then the energy is released through chemical-looping combustion, which only produces water and no other pollutants; moreover, compared with traditional hydrogen combustion for energy release, chemical-looping combustion has higher safety.

[0080] Finally, it should be noted that the methods and devices described in detail above are only examples, and those skilled in the art can modify these examples in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A power plant boiler mixed with biomass fuel coupled chemical chain combustion system, characterized by: include, A water electrolysis device (1), wherein the water electrolysis device (1) is connected to a fuel reactor (5) and a second gas mixer (12), and the fuel reactor (5) is connected to an air reactor (4); A first gas mixer (8), the first gas mixer (8) being connected to the air reactor (4); Boiler body (21); A biomass crusher (9), wherein the biomass crusher (9) is connected to a boiler body (21), and the biomass crusher (9) is connected to an air reactor (4); The boiler body (21) is connected to the first gas mixer (8).

2. The power plant boiler biomass fuel coupled chemical chaining combustion system according to claim 1 is characterized by: Also includes an oxygen storage tank (2) and a hydrogen storage tank (3); The oxygen storage tank (2) and the hydrogen storage tank (3) are connected to the water electrolysis device (1); The oxygen storage device (2) is used to store the generated oxygen; The hydrogen storage tank (3) is used to store the generated hydrogen.

3. The power plant boiler biomass fuel coupled chemical chaining combustion system according to claim 2 is characterized by: The boiler body (21) is provided with a biomass nozzle (13), a pulverized coal nozzle (14), and a burnout air nozzle (15) in sequence from bottom to top; The biomass nozzle (13) is connected to the biomass crusher (9); The second gas mixer (12) is connected to the overfire air nozzle (15).

4. The power plant boiler biomass fuel coupled chemical chaining combustion system according to claim 3 is characterized by: The fuel reactor (5) is connected to a condenser (10), and the condenser (10) is connected to a water storage tank (11).

5. The power plant boiler biomass fuel coupled chemical chaining combustion system according to claim 4 is characterized by: The first gas mixer (8) is provided with a first induced draft fan (6) and a first blower fan (7); The first induced draft fan (6) is connected to the boiler body (21).

6. The power station boiler biomass fuel coupled chemical chaining combustion system according to claim 5 is characterized by: The boiler body (21) is provided with an air preheater (17), and the air preheater (17) is connected to a second air blower (16).

7. The power station boiler biomass fuel coupled chemical chaining combustion system according to claim 6 is characterized by: The air preheater (17) is connected to a dust collector (18), the dust collector (18) is connected to a second induced draft fan (19), and the dust collector (18) is connected to a chimney (20) via the second induced draft fan (19).

8. A method for coupling chemical chain combustion of biomass fuels to power plant boilers, applied to the power plant boiler coupling chemical chain combustion system of biomass fuels to power plant boilers according to claim 7, characterized in that: include, Electrolyzing water using a water electrolysis device (1); The products generated by electrolysis of water are respectively introduced into the fuel reactor (5) and the second gas mixer (12); The biomass fuel powder produced by the biomass crusher (9) is transported to the biomass nozzle (13) by using the high-temperature flue gas and air mixed gas in the flue; The second blower (16) passes the primary air, the secondary air and the burnt-out air into the air preheater (17) for preheating; The flue gas generated by the combustion of the boiler body (21) can be dedusted in the dust collector (18) and then discharged through the induced draft fan (19) and the chimney (20).

9. The method for coupling chemical chaining combustion with biomass fuel in power plant boilers according to claim 8, characterized in that: The hydrogen in the hydrogen storage tank (3) is introduced into the fuel reactor (5) for reaction, reducing the oxide carrier to a metal carrier to generate water, while the metal carrier in the air reactor (4) undergoes an oxidation reaction with the air to generate metal oxides and release a large amount of heat; Part of the oxygen in the oxygen storage tank (2) is collected as a chemical product, and the other part is mixed with air in the second gas mixer (12) to obtain oxygen-enriched burnout air, which is finally sent into the furnace through the burnout air nozzle (15) for combustion.

10. The method for coupling chemical chaining combustion with biomass fuel in power plant boilers according to claim 8 or 9, characterized in that: The high-temperature flue gas in the flue is introduced into the first gas mixer (8) by the first induced draft fan (6) to be mixed with the air sent in by the first blower (7), and the resulting two-medium mixed gas is sent to the air reactor (4) for heat exchange, and the large amount of heat released in the chemical chain combustion is used to preheat the two-medium mixed gas; The preheated two-medium mixed gas is used to transport the biomass fuel powder produced by the biomass crusher (9) to the biomass nozzle (13) in a direct blowing manner.

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