System and method for producing cement clinker by coupling oxygen-enriched combustion with green energy

Abstract

The invention relates to the technical field of cement manufacturing, and provides a system for producing cement clinker by coupling oxygen-enriched combustion with green energy. The system comprises a clinker sintering system, a high-temperature fan, a heat exchanger I, a dust collector, a raw material gas purification system, a circulating fan, a water removal device, a heat exchanger II, a sealing system, an air compressor device, a pulverized coal conveying system, an ash removal system, a conveying fan, an oxygen and gas production system, a raw material drying system, a coal mill drying system and a clinker warehouse. The clinker firing system comprises a grate cooler, a rotary kiln, a kiln head burner, a kiln head cover, a smoke chamber, a decomposing furnace, a kiln tail burner, preheaters at all levels and a pressure reamer; the feed gas purification system comprises an absorption tower, an SCR device, a heat exchanger III, a pressure swing adsorption device, an exhaust fan, a hot air device, a regeneration tower and a sulfur recovery device. The method has the effect of reducing the oxygen production cost and the denitration cost in the cement production process.

Description

Technical Field

[0001] The present application relates to the technical field of cement manufacturing, and in particular to a system and method for producing cement clinker by coupling oxygen-enriched combustion with green energy. Background Art

[0002] Environmental pollution and energy shortages are driving the world to accelerate its transition to low-carbon and clean energy. In this context, the Integrated Energy System (IES) with multi-energy complementarity and multi-source synergy optimization has become a key research area to solve the contradiction between energy supply and demand and improve energy conversion efficiency.

[0003] The cement industry is one of the main sources of global carbon emissions, accounting for 7%-8% of global carbon emissions. Among them, about 9% of carbon emissions come from purchased electricity, while thermal power accounts for 71% of the power supply in the domestic power structure. With increasingly stringent policies and regulations, the pressure on carbon reduction faced by the cement industry continues to increase. Therefore, it has become a trend to use renewable energy to replace part of the purchased electricity to reduce carbon emissions.

[0004] Carbon capture, utilization and storage (CCUS) technology is regarded as a key technical approach for global emission reduction actions, especially in the cement industry. At present, mainstream carbon capture technologies are mainly divided into three categories: capture before combustion, during combustion (oxygen-enriched combustion) and after combustion. Oxygen-enriched combustion carbon capture technology involves using a mixture of high-concentration oxygen and carbon dioxide to replace air, and react with fuels such as pulverized coal in the kiln. Oxygen is usually obtained through industrial-grade air separation units, while carbon dioxide is recovered from the flue gas emitted by the kiln through flue gas circulation. Through continuous carbon dioxide circulation, the concentration of carbon dioxide in the flue gas gradually increases. Oxygen-enriched combustion has many advantages over air combustion, such as increasing flame temperature and heating efficiency, as well as reducing smoke exhaust and heat loss. However, oxygen-enriched combustion requires the creation of a high-oxygen environment, which leads to high oxygen production costs and a large amount of electricity consumption.

[0005] In practical applications, power-to-gas technology is divided into two types: power-to-hydrogen and power-to-methane. Power-to-hydrogen is the pre-reaction of power-to-methane. The basic principle of power-to-hydrogen is to produce hydrogen and oxygen by electrolysis of water. Although the storage and transmission of hydrogen produced by water electrolysis are difficult, the unit energy density of methane is four times that of hydrogen, and it is easy to store and transmit, so the power-to-methane method is usually adopted. Power-to-methane is based on the electrolysis of hydrogen, using carbon dioxide and hydrogen to react under high temperature and high pressure to generate methane. The power-to-gas device consumes a lot of electricity during operation. As an important energy coupling device in IES, the large amount of high-purity oxygen produced during its operation has not been fully utilized.

[0006] At present, the oxygen-enriched combustion carbon capture technology used in the cement industry faces the problems of low efficiency, high system investment and operating costs. There are still deficiencies in terms of process layout, oxygen production costs, development of applicable equipment, and measures to prevent air leakage. In addition, the traditional denitrification method in the industry uses ammonia water, which brings the risk of ammonia escape. Therefore, it is urgent to explore a denitrification technology suitable for use under the conditions of high CO2 partial pressure of oxygen-enriched combustion flue gas. In order to reduce carbon emissions from cement plants, it is urgent to establish a comprehensive energy system that can achieve multiple energy complementarity and multi-source coordinated optimization. Summary of the invention

[0007] In order to reduce the oxygen production cost and denitrification cost in the cement production process, the present application provides a system for producing cement clinker by coupling oxygen-enriched combustion with green energy.

[0008] In the first aspect, the present application provides a system for producing cement clinker by coupling oxygen-enriched combustion with green energy, which adopts the following technical solution: A system for producing cement clinker by coupling oxygen-enriched combustion with green energy, comprising the following systems or devices connected by pipelines: Clinker burning system, high temperature fan, heat exchanger 1, dust collector, raw gas purification system, circulating fan, water removal device, heat exchanger 2, sealing system, air compressor device, coal powder conveying system, ash cleaning system, conveying fan, oxygen and gas production system, raw material drying system, coal mill drying system, clinker storage; The clinker burning system comprises a grate cooler, a rotary kiln, a kiln head burner, a kiln head hood, a smoke chamber, a decomposition furnace, a kiln tail burner, preheaters at various levels and a pressure reamer; wherein the grate cooler is divided into three cooling zones, namely, a first cooling zone, a second cooling zone and a third cooling zone connected in sequence; the preheaters at various levels are divided into first to fifth stage preheaters, and the first stage preheater to the fifth stage preheater are connected in sequence; The pressure reamer is connected to the connecting pipe between the second-stage preheater and the first-stage preheater, the fifth-stage preheater is connected to the decomposition furnace, and the kiln tail burner is arranged on the decomposition furnace; the decomposition furnace is connected to the smoke chamber, the smoke chamber is connected to one end of the rotary kiln, and the other end of the rotary kiln is connected to the kiln head cover and the first cooling zone; the kiln head burner is arranged on the kiln head cover, and the kiln head cover connects the first cooling zone and the decomposition furnace; The first stage preheater, the high temperature fan, the first heat exchanger, the dust collector and the circulating fan are connected in sequence, the dust collector is respectively connected to the raw gas purification system and the circulating fan, the circulating fan is respectively connected to the dehydration device and the chimney, the dehydration device is respectively connected to the second heat exchanger, the sealing system, the first cooling zone and the second cooling zone; The second heat exchanger is respectively connected to the air compressor device, the conveying fan and the pulverized coal conveying system, the air compressor device is connected to the ash cleaning system, the conveying fan is respectively connected to the kiln head burner and the kiln tail burner; the pulverized coal conveying system is respectively connected to the kiln head burner and the kiln tail burner; the second cooling zone is connected to the connecting pipeline between the decomposition furnace and the fifth stage preheater, and the third cooling zone is respectively connected to the raw material drying system and the coal mill drying system; The raw gas purification system includes an absorption tower, an SCR device, a heat exchanger 3, a pressure swing adsorption device, an exhaust fan, a hot air device, a regeneration tower and a sulfur recovery device; The oxygen and gas production system comprises a wind-photovoltaic power generation system, a CH4 storage tank, a methanation device, an electric-to-gas device, an oxygen storage tank and an oxygen production device. The wind-photovoltaic power generation system is respectively connected to the electric-to-gas device, the methanation device and the oxygen production device. The oxygen production device is respectively connected to the oxygen storage tank and the kiln head burner, the kiln tail burner and the first cooling zone. The oxygen storage tank is respectively connected to the kiln head burner, the kiln tail burner and the first cooling zone; the electric-to-gas device is respectively connected to the oxygen storage tank, the methanation device, the kiln head burner, the kiln tail burner, the CH4 storage tank and the raw gas purification system. The CH4 storage tank is connected to the kiln tail burner, the SCR device, the hot air device and the smoke chamber outlet. The outlet of the decomposition furnace is provided with a flue gas analysis device, which is used to calculate the nitrogen oxide content and CaO content at the outlet of the decomposition furnace. A methane denitrifier is provided at the outlet of the smoke chamber.

[0009] By adopting the above technical solutions, the wind-photovoltaic power generation system, together with the external power grid, provides the required electricity for the oxygen production device and the power-to-gas device. The oxygen and gas production system can achieve effective scheduling of peak and valley periods and the intensity of wind and solar resources by flexibly adjusting the output plan and energy distribution of each device. In this process, wind and photovoltaic power generation are given priority.

[0010] The O2 produced by the oxygen production device is stored in the oxygen storage tank or directly transported to the kiln head burner, kiln tail burner, and the first cooling zone of the grate cooler for use. The power-to-gas device electrolyzes water to generate O2 and H2, of which O2 is stored in the oxygen storage tank or directly transported to the kiln head burner, kiln tail burner, and the first cooling zone of the grate cooler for use. H2 and high-concentration CO2 from the raw gas purification system enter the methanation device, and a methanation reaction occurs under the action of the catalyst to generate CH4, which is stored in the CH4 storage tank.

[0011] The function of the oxygen storage tank is to realize the use of oxygen across time periods. When the output power of the wind and photovoltaic power generation systems is high, the electricity they provide is used for the oxygen generator and the power-to-gas device. Part of the oxygen produced is used in the burner and cooling area, and the rest is stored in the oxygen storage tank. On the contrary, when the output power of the wind-photovoltaic power generation system is low and cannot meet the system's demand for oxygen-rich operation, the oxygen storage tank will supplement the oxygen difference. If there is still a shortage, the external power grid will intervene to supplement the power supply to produce oxygen.

[0012] The CH4 storage tank allows methane to be used in different time spans. The methane in the tank has four uses: one part is used as auxiliary fuel to stably supply the kiln tail burner to reduce the system's demand for coal powder (at this time, methane is mainly used for combustion and provides heat); another part is used as a reducing agent and transported to the methane denitrifier at the smoke chamber outlet to remove most of the nitrogen oxides (at this time, methane is mainly used to remove nitrogen oxides); another part is used as a reducing agent and sent to the SCR device to remove the remaining nitrogen oxides to avoid methane catalyst poisoning (at this time, methane is also mainly used to remove nitrogen oxides); the last part of methane is sent to the hot air device for combustion to provide heat energy.

[0013] The flue gas analysis device at the outlet of the decomposition furnace can calculate and obtain three indicators of nitrogen oxide content, CaO content and CO content at the outlet of the decomposition furnace and transmit them to the processor. The kiln tail burner and methane denitrification device are coordinated and feedback-regulated by the processor (the methane denitrification device adjusts the flow rate of methane introduced, and the kiln tail burner adjusts the flow rate of coal powder and methane introduced).

[0014] When the flue gas analysis device detects an increase in the concentration of nitrogen oxides, the methane denitrifier will increase the injection of methane, thereby reducing the concentration of nitrogen oxides in the flue gas. Once the concentration of nitrogen oxides drops to a certain threshold and stabilizes, the methane denitrifier will maintain the current injection amount unchanged. At the same time, it is necessary to adjust the flow rate of pulverized coal and methane in the kiln tail burner to optimize the CaO content and ensure that it is as high as possible (this reflects the decomposition efficiency of the raw meal), while reducing the CO content to increase the burnout rate of the fuel. If a decrease in the CaO content is detected, it indicates that the heat supply is insufficient. At this time, the flow rate of pulverized coal and methane in the kiln tail burner should be increased to supplement the heat, but this may also cause a slight increase in the concentration of nitrogen oxides. If the CO content increases, it means that the fuel is not completely burned, and the oxygen supply needs to be increased. In summary, the goal is to find a balance between three key parameters: reduce the concentration of nitrogen oxides as much as possible, increase the CaO content, and reduce the CO content.

[0015] This solution can significantly reduce the investment and operating costs of carbon dioxide purification equipment by increasing the dry basis concentration of carbon dioxide (CO2) in the circulating gas to more than 80%. In the temperature range of 1050-1100℃, the high CO2 partial pressure in the flue gas helps to improve the denitrification efficiency of methane (CH4). The system combines the high CO2 partial pressure and temperature characteristics of the smoke chamber outlet of the oxyfuel carbon capture production line, introduces CH4 at the smoke chamber outlet to remove most of the nitrogen oxides (NOx), and sets up a selective catalytic reduction (SCR) device in the subsequent process to use CH4 for secondary denitrification to prevent methane catalyst poisoning. In addition, the system uses wind power and photovoltaic power generation as renewable green energy, effectively reducing the operating costs of the oxygen generator, power-to-gas device and methanation device.

[0016] As a key energy conversion device in the integrated energy system (IES), the power-to-gas device fully utilizes the high-purity oxygen produced during operation, which not only broadens the source of oxygen but also further reduces the cost of oxygen production. The system uses part of the high-concentration CO2 as the reaction raw material of the methanation device, and the generated methane (CH4) is used as both the fuel of the cement burning system and the denitrification reducing agent, realizing the carbon cycle within the system, thereby reducing coal consumption and denitrification costs.

[0017] Preferably, the sealing system includes a kiln head sealing device, a kiln tail sealing device and improved inspection doors, valves, holes and covers at various locations in the system; the sealing system also includes a piping system connecting various sealing points.

[0018] Preferably, the kiln head sealing device adopts a double-layer fish scale sealing structure.

[0019] Preferably, the kiln head sealing device includes a friction ring, a sealing cover and a plurality of sealing sheets, the friction ring is arranged on the outer side wall of the rotary kiln, and the sealing cover is connected to the kiln head cover; each of the sealing sheets is stacked into a double-layer fish-scale annular cover body, one end of the annular cover body is pressed on the friction ring, and the other end is fixed on the sealing cover, and each of the sealing sheets, the friction ring and the sealing cover enclose an isolation chamber; wherein, the sealing cover is provided with a circulating gas inlet 1, a circulating gas inlet 2 and a circulating gas outlet.

[0020] Preferably, the kiln tail sealing device adopts a double-layer sealing structure of compression sealing and fish scale sealing.

[0021] Preferably, the kiln tail sealing device includes a compression seal fixed end, a compression seal rotating end, an isolation cover, a plurality of fish scales and a contact ring, the contact parts of the compression seal fixed end and the compression seal rotating end form a friction pair, constituting a compression seal structure; the isolation cover is arranged on the side wall of the smoke chamber, each of the fish scales is stacked into a fish scale-shaped annular cover body, and one end is fixed on the isolation cover, and the other end is pressed on the contact ring, and the contact ring is arranged on the compression seal rotating end, and the isolation cover, the fish scales, the contact ring, the compression seal fixed end and the compression seal rotating end together form a sealing cavity.

[0022] Preferably, the dust collector adopts a high-box shed structure, including a shell, a shed, a pulse cleaning device, a double-layer inspection door and an air lock valve. The shed is a closed structure and is arranged on the upper part of the shell. A plurality of double-layer inspection doors are arranged on the shed, and a closed partition cavity is formed in the middle of the double-layer inspection door. The air lock valve is provided at the lower part of the shell.

[0023] Preferably, the cleaning system includes an air cannon, a pulse cleaning device and a pipeline system connecting various cleaning points.

[0024] In the second aspect, the present application also provides a method for producing cement clinker by coupling oxygen-enriched combustion with green energy, which adopts the following technical solution: A method for producing cement clinker by using the above-mentioned system of oxygen-enriched combustion coupled with green energy comprises the following steps: S1, the raw material is input into the connecting pipes of the first stage preheater and the second stage preheater through a pressure reamer, and heat exchange is carried out with the circulating gas rich in high concentration of CO2 in the pipeline, and then enters the first stage preheater with the circulating gas; S2, the raw meal in the circulating gas is collected by the first stage preheater and enters the connecting pipe between the third stage preheater and the second stage preheater, and then enters the second stage preheater after heat exchange with the circulating gas therein. The raw meal successively exchanges heat with the circulating gas in the second to fourth stage preheaters and then enters the decomposition furnace; S3. After pre-decomposition in the decomposition furnace, the raw material enters the fifth-stage preheater, is collected by the fifth-stage preheater, and then enters the smoke chamber, and then enters the rotary kiln. After being burned into clinker in the rotary kiln, it enters the grate cooler for cooling. After being cooled to the required temperature, it is stored in the clinker warehouse.

[0025] By adopting the above technical solution, the raw meal is input into the system through the pressure reamer, and heat is exchanged with the circulating gas rich in high concentration of CO2 at the connecting pipe from the second stage preheater to the first stage preheater, and then flows into the first stage preheater with the circulating gas. When the pressure reamer is working, the inside is filled with raw meal, and the spiral blades push the raw meal into the system, effectively isolating the air in the form of a material seal. The raw meal in the circulating gas is collected in the first stage preheater, and then enters the connecting pipe between the third stage preheater and the second stage preheater, where it is heat exchanged with the circulating gas again, and then flows into the second stage preheater.

[0026] After continuous heat exchange with the circulating gas in the second to fourth stage preheaters, the raw meal finally enters the calciner, where it is pre-calcined. The pre-calcined raw meal enters the fifth stage preheater, and after being collected, it enters the smoke chamber, and then enters the rotary kiln. After being burned into clinker in the rotary kiln, the clinker enters the first cooling zone of the grate cooler. The clinker passes through the first, second, and third cooling zones of the grate cooler in turn, and after being cooled to the required temperature, it finally enters the clinker warehouse for storage.

[0027] In summary, the present application includes at least one of the following beneficial technical effects: (1) This scheme uses wind power and solar photovoltaic power generation as renewable green energy, effectively reducing the operating costs of oxygen production, power-to-gas and methanation equipment. The power-to-gas equipment is the core energy conversion equipment in the integrated energy system (IES). The high-purity oxygen produced during its operation is fully utilized, which not only increases the supply source of oxygen, but also further reduces the cost of oxygen production. Green electricity converts part of the high-concentration carbon dioxide into the reaction raw materials of the power-to-gas equipment, which not only reduces the cost of carbon sequestration, but also the methane (CH4) produced can be used as fuel and denitrification agent for the cement burning system, realizing the carbon cycle within the system, thereby reducing coal consumption and denitrification costs.

[0028] (2) This solution not only solves the problems of insufficient adaptation of equipment and serious air leakage in the cement industry's oxygen-enriched combustion, but also reduces the system's operating costs by utilizing renewable energy. It also converts and stores renewable energy during peak output periods and provides energy during power shortage periods, thereby improving the system's renewable energy absorption capacity and operational regulation capabilities, while taking into account both carbon reduction effects and operational benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of a system for producing cement clinker in an embodiment of the present application; Figure 2 is a process flow chart of a clinker burning system in an embodiment of the present application; Figure 3 is a process flow chart of a raw gas purification system in an embodiment of the present application; Figure 4It is a structural schematic diagram of a kiln head sealing device in an embodiment of the present application; Figure 5 It is a structural schematic diagram of the kiln tail sealing device in the embodiment of the present application; Figure 6 This is a front view of the dust collector in the embodiment of the present application; Figure 7 is a side view of a dust collector in an embodiment of the present application; Figure 8 It is a structural schematic diagram of the kiln tail burner in the embodiment of the present application.

[0030] Figure numerals: 1. Clinker burning system; 2. High temperature fan; 3. Heat exchanger 1; 4. Dust collector; 5. Raw gas purification system; 6. Circulation fan; 7. Water removal device; 8. Heat exchanger 2; 9. Sealing system; 10. Air compressor device; 11. Coal powder conveying system; 12. Ash cleaning system; 13. Conveying fan; 14. Oxygen and gas production system; 15. Raw material drying system; 16. Coal mill drying system; 17. Clinker storage; 18. Grate cooler; 19. Rotary kiln; 20, kiln head burner; 21, kiln head cover; 22, smoke chamber; 23, decomposition furnace; 24, kiln tail burner; 25, preheaters at all levels; 26, pressure reamer; 27, first cooling zone; 28, second cooling zone; 29, third cooling zone; 30, first stage preheater; 31, second stage preheater; 32, third stage preheater; 33, fourth stage preheater; 34, fifth stage preheater; 35, absorption tower; 36, SCR device; 37 , heat exchanger three; 38, pressure swing adsorption device; 39, oxygen production device; 40, hot air device; 41, regeneration tower; 42, sulfur recovery device; 43, wind-photovoltaic power generation system; 44, CH4 storage tank; 45, methanation device; 46, power-to-gas device; 47, oxygen storage tank; 48, kiln head sealing device; 49, kiln tail sealing device; 50, friction ring; 51, sealing cover; 52, sealing sheet; 53, isolation chamber; 54, circulating gas inlet one; 5 5. Circulating gas inlet 2; 56. Circulating gas outlet; 57. Compression seal fixed end; 58. Compression seal rotating end; 59. Isolation cover; 60. Fish scale; 61. Contact ring; 62. Sealing chamber; 63. Shell; 64. Leaning house; 65. Pulse cleaning device; 66. Double-layer inspection door; 67. Air lock valve; 68. Circulating gas inlet 3; 69. Partition chamber; 70. Friction pair; 71. Flue gas analysis device; 72. Methane denitrifier; 73. Chimney. DETAILED DESCRIPTION

[0031] The technical solution of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. The present application can be embodied in many different forms and is not limited to the embodiments described here.

[0032] In the description of the present application, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics represented in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics represented can be combined in any one or more embodiments or examples in a suitable manner.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0034] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection; it can also be a detachable connection; or integrated; it can also be a mechanical connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0035] Some embodiments of the present application are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples shown in the present application.

[0036] The present application embodiment discloses a system for producing cement clinker by coupling oxygen-enriched combustion with green energy. Figure 1 and Figure 2 The system for producing cement clinker includes the following systems or devices connected by pipelines: clinker burning system 1, high-temperature fan 2, heat exchanger 1 3, dust collector 4, raw gas purification system 5, circulating fan 6, water removal device 7, heat exchanger 2 8, sealing system 9, air compressor device 10, coal powder conveying system 11, ash cleaning system 12, conveying fan 13, oxygen and gas production system 14, raw material drying system 15, coal mill drying system 16, clinker storage 17.

[0037] Specifically, the clinker burning system 1 includes a grate cooler 18, a rotary kiln 19, a kiln head burner 20, a kiln head hood 21, a smoke chamber 22, a decomposition furnace 23, a kiln tail burner 24, preheaters 25 at various levels and a pressure reamer 26; wherein the grate cooler 18 is divided into three cooling zones, namely a first cooling zone 27, a second cooling zone 28 and a third cooling zone 29 which are connected in sequence; the preheaters 25 at various levels are divided into first to fifth stage preheaters 34, and the first stage preheaters 30 to the fifth stage preheaters 34 are connected in sequence.

[0038] The pressure reamer 26 connects the connecting pipe between the second-stage preheater 31 and the first-stage preheater 30, the fifth-stage preheater 34 is connected to the decomposition furnace 23, and the kiln tail burner 24 is installed on the decomposition furnace 23; the decomposition furnace 23 is connected to the smoke chamber 22, the smoke chamber 22 is connected to one end of the rotary kiln 19, and the other end of the rotary kiln 19 is connected to the kiln head hood 21 and the first cooling zone 27; the kiln head burner 20 is installed on the kiln head hood 21, and the kiln head hood 21 connects the first cooling zone 27 and the decomposition furnace 23.

[0039] The first-stage preheater 30, the high-temperature fan 2, the heat exchanger 1 3, the dust collector 4 and the circulating fan 6 are connected in sequence, the dust collector 4 is respectively connected to the raw gas purification system 5 and the circulating fan 6, the circulating fan 6 is respectively connected to the dehydration device 7 and the chimney 73, the dehydration device 7 is respectively connected to the heat exchanger 2 8, the sealing system 9, the first cooling zone 27 and the second cooling zone 28.

[0040] The heat exchanger 2 8 is respectively connected to the air compressor device 10, the conveying fan 13 and the coal powder conveying system 11, the air compressor device 10 is connected to the ash cleaning system 12, and the conveying fan 13 is respectively connected to the kiln head burner 20 and the kiln tail burner 24; the coal powder conveying system 11 is respectively connected to the kiln head burner 20 and the kiln tail burner 24; the second cooling zone 28 is connected to the connecting pipeline between the decomposition furnace 23 and the fifth stage preheater 34, and the third cooling zone 29 is respectively connected to the raw material drying system 15 and the coal mill drying system 16.

[0041] Combination Figure 3The raw gas purification system 5 includes an absorption tower 35, an SCR device 36, a heat exchanger 37, a pressure swing adsorption device 38, an exhaust fan, a hot air device 40, a regeneration tower 41 and a sulfur recovery device 42. The oxygen and gas production system 14 includes a wind-photovoltaic power generation system 43, a CH4 storage tank 44, a methanation device 45, an electric-to-gas device 46, an oxygen storage tank 47 and an oxygen production device 39. The wind-photovoltaic power generation system 43 is respectively connected to the electric-to-gas device 46, the methanation device 45 and the oxygen production device 39. The oxygen production device 39 is respectively connected to the oxygen storage tank 47 and the kiln head burner 20, the kiln tail burner 24, and the first cooling zone 27. The oxygen storage tank 47 is respectively connected to the kiln head burner 20, the kiln tail burner 24 and the first cooling zone 27; the electric-to-gas device 46 is respectively connected to the oxygen storage tank 47, the methanation device 45, the kiln head burner 20, the kiln tail burner 24, the first cooling zone 27, the CH4 storage tank 44 and the raw gas purification system 5, and the CH4 storage tank 44 is connected to the kiln tail burner 24, the SCR device 36, the hot air device 40 and the smoke chamber 22 outlet. A flue gas analysis device 71 is fixedly installed at the outlet of the decomposition furnace 23 , and the flue gas analysis device 71 is used to calculate the nitrogen oxide content and CaO content at the outlet of the decomposition furnace 23 . A methane denitrifier 72 is also installed at the outlet of the smoke chamber 22 .

[0042] Reference Figure 4 and Figure 5 , the sealing system 9 includes a kiln head sealing device 48, a kiln tail sealing device 49 and improved inspection doors, valves, holes and covers at various locations of the system; the sealing system 9 also includes a pipeline system connecting various sealing points. In this embodiment, the kiln head sealing device 48 adopts a double-layer fish scale sealing structure, including a friction ring 50, a sealing cover 51 and a plurality of sealing sheets 52. The friction ring 50 is fixed on the outer wall of the rotary kiln 19, and the sealing cover 51 is fixed on the kiln head cover 21; each sealing sheet 52 is stacked into a double-layer fish scale annular cover body, one end of the annular cover body is pressed on the friction ring 50, and the other end is fixed on the sealing cover 51. Each sealing sheet 52, the friction ring 50 and the sealing cover 51 enclose an isolation chamber 53; wherein, the sealing cover 51 is provided with a circulating gas inlet 1 54, a circulating gas inlet 2 55 and a circulating gas outlet 56.

[0043] The kiln tail sealing device 49 adopts a double-layer sealing structure of compression sealing and fish scale sealing, including a compression sealing fixed end 57, a compression sealing rotating end 58, an isolation cover 59, a plurality of fish scales 60 and a contact ring 61. The contact portion of the compression sealing fixed end 57 and the compression sealing rotating end 58 forms a friction pair 70, constituting a compression sealing structure; the isolation cover 59 is fixed on the side wall of the smoke chamber 22, and each fish scale 60 is stacked into a fish scale-shaped annular cover body, and one end is fixed on the isolation cover 59, and the other end is pressed on the contact ring 61, and the contact ring 61 is fixed on the compression sealing rotating end 58, and the isolation cover 59, the fish scale 60, the contact ring 61, the compression sealing fixed end 57 and the compression sealing rotating end 58 together enclose a sealing cavity 62.

[0044] In addition, refer to Figure 6 and Figure 7 The dust collector 4 adopts a high box shed 64 structure, including a shell 63, a shed 64, a pulse cleaning device 65, a double-layer inspection door 66 and a wind lock valve 67. The shed 64 is a closed structure and is fixed to the upper part of the shell 63. A plurality of double-layer inspection doors 66 are installed on the shed 64. A closed partition chamber 69 is formed in the middle of the double-layer inspection door 66. A wind lock valve 67 is provided at the lower part of the shell 63. The cleaning system 12 includes an air cannon, a pulse cleaning device 65 and a pipeline system connecting various cleaning points.

[0045] The implementation principle of the system for producing cement clinker by coupling oxygen-enriched combustion with green energy in the embodiment of the present application is as follows: the wind-photovoltaic power generation system 43, together with the external power grid, provides the required power for the oxygen production device 39 and the power-to-gas device 46. The oxygen production and gas production system 14 achieves effective scheduling of peak and valley periods and the intensity of wind and solar resources by flexibly adjusting the output plan and energy allocation of each device. In this process, wind power and photovoltaic power generation are preferentially used.

[0046] The O2 produced by the oxygen production device 39 enters the oxygen storage tank 47 for storage or is directly transported to the kiln head burner 20, the kiln tail burner 24, and the first cooling zone 27 of the grate cooler 18 for use. The power-to-gas device 46 electrolyzes water to generate O2 and H2, of which O2 enters the oxygen storage tank 47 for storage or is directly transported to the kiln head burner 20, the kiln tail burner 24, and the first cooling zone 27 of the grate cooler 18 for use. H2 and high-concentration CO2 from the raw gas purification system 5 enter the methanation device 45, and a methanation reaction occurs under the action of a catalyst to generate CH4, which enters the CH4 storage tank 44 for storage.

[0047] The function of the oxygen storage tank 47 is to realize the use of oxygen across time periods. When the output power of the wind power and photovoltaic power generation systems is high, the electricity they provide is used for the oxygen production device 39 and the power-to-gas device 46, and part of the oxygen produced is used for the burner and the cooling area, and the rest is stored in the oxygen storage tank 47. On the contrary, when the output power of the wind-photovoltaic power generation system 43 is low and cannot meet the system's demand for oxygen-enriched operation, the oxygen storage tank 47 will supplement the oxygen difference. If there is still a shortage, the external power grid will intervene to supplement the power supply to produce oxygen.

[0048] The CH4 storage tank 44 allows methane to be used in different time spans. The methane in the tank has four uses: one part is used as auxiliary fuel to stably supply the kiln tail burner 24 to reduce the system's demand for coal powder (at this time, methane is mainly used for combustion and provides heat); another part is used as a reducing agent and is transported to the methane denitrifier 72 at the outlet of the smoke chamber 22 to remove most of the nitrogen oxides (at this time, methane is mainly used to remove nitrogen oxides); another part is used as a reducing agent and is sent to the SCR device 36 to remove the remaining nitrogen oxides to avoid poisoning of the methane catalyst (at this time, methane is also mainly used to remove nitrogen oxides); the last part of the methane is sent to the hot air device 40 for combustion to provide heat energy.

[0049] The flue gas analysis device 71 at the outlet of the decomposition furnace 23 can calculate and obtain the nitrogen oxide content, CaO content, and CO content at the outlet of the decomposition furnace 23. The three indicators are transmitted to the processor. The kiln tail burner 24 and the methane denitrifier 72 are coordinated and feedback-regulated by the processor (the methane denitrifier 72 adjusts the flow rate of methane introduced, and the kiln tail burner 24 adjusts the flow rate of coal powder and methane introduced).

[0050] When the flue gas analysis device 71 detects an increase in the concentration of nitrogen oxides, the methane denitrifier 72 will increase the injection amount of methane, thereby reducing the concentration of nitrogen oxides in the flue gas. Once the concentration of nitrogen oxides drops to a certain threshold and stabilizes, the methane denitrifier 72 will maintain the current injection amount unchanged. At the same time, it is necessary to adjust the flow of pulverized coal and methane in the kiln tail burner 24 to optimize the CaO content and ensure that it is as high as possible (this reflects the decomposition efficiency of the raw material), while reducing the CO content to increase the burnout rate of the fuel. If a decrease in the CaO content is detected, it indicates that the heat supply is insufficient. At this time, the flow of pulverized coal and methane in the kiln tail burner 24 should be increased to supplement the heat, but this may also cause a slight increase in the concentration of nitrogen oxides. If the CO content increases, it means that the fuel is not completely burned, and the oxygen supply needs to be increased. In summary, the goal is to find a balance between the three key parameters: reduce the concentration of nitrogen oxides as much as possible, increase the CaO content, and reduce the CO content.

[0051] This solution can significantly reduce the investment and operating costs of carbon dioxide purification equipment by increasing the dry basis concentration of carbon dioxide (CO2) in the circulating gas to more than 80%. In the temperature range of 1050-1100°C, the high CO2 partial pressure in the flue gas helps to improve the denitrification efficiency of methane (CH4). The system combines the high CO2 partial pressure and temperature characteristics of the smoke chamber 22 outlet of the oxygen-enriched combustion carbon capture production line, introduces CH4 at the smoke chamber 22 outlet to remove most of the nitrogen oxides (NOx), and sets a selective catalytic reduction (SCR) device in the subsequent process to use CH4 for secondary denitrification to prevent methane catalyst poisoning. In addition, the system uses wind power and photovoltaic power generation as renewable green energy, which effectively reduces the operating costs of the oxygen production device 39, the power-to-gas device 46 and the methanation device 45.

[0052] As a key energy conversion device in the integrated energy system (IES), the power-to-gas device 46 fully utilizes the high-purity oxygen generated during operation, which not only broadens the source of oxygen but also further reduces the cost of oxygen production. The system uses part of the high-concentration CO2 as the reaction raw material of the methanogenization device 45, and the generated methane (CH4) is used as both a fuel for the cement burning system and a denitrification reducing agent, realizing the carbon cycle within the system, thereby reducing coal consumption and denitrification costs.

[0053] Based on the above embodiment, the present application also provides a method for producing cement clinker by using the above oxygen-enriched combustion coupled with green energy, including the following steps: S1, the raw material is input into the connecting pipe of the first stage preheater 30 and the second stage preheater 31 through the pressure reamer 26, and heat exchange is carried out with the circulating gas rich in high concentration of CO2 in the pipeline, and enters the first stage preheater 30 with the circulating gas; S2, the raw meal in the circulating gas is collected by the first stage preheater 30 and enters the connecting pipe between the third stage preheater 32 and the second stage preheater 31, and enters the second stage preheater 31 after heat exchange with the circulating gas therein, and the raw meal successively exchanges heat with the circulating gas in the second to fourth stage preheaters and enters the decomposition furnace 23; S3, the raw material is pre-decomposed in the decomposition furnace 23 and then enters the fifth-stage preheater 34. After being collected by the fifth-stage preheater 34, it enters the smoke chamber 22, and then enters the rotary kiln 19. After being burned into clinker in the rotary kiln 19, it enters the grate cooler 18 for cooling. After being cooled to the required temperature, it enters the clinker storage 17 for storage.

[0054] The raw meal is input into the system through the pressure reamer 26, and heat exchanged with the circulating gas rich in high concentration of CO2 at the connecting pipe from the second stage preheater 31 to the first stage preheater 30, and then flowed into the first stage preheater 30 with the circulating gas. When the pressure reamer 26 is working, the inside is filled with raw meal, and the spiral blades push the raw meal into the system, effectively isolating the air in the form of a material seal. The raw meal in the circulating gas is collected in the first stage preheater 30, and then enters the connecting pipe between the third stage preheater 32 and the second stage preheater 31, where it heat exchanges with the circulating gas again, and then flows into the second stage preheater 31.

[0055] After continuous heat exchange with the circulating gas in the second-stage preheater 31 to the fourth-stage preheater 33, the raw material finally enters the decomposition furnace 23, where it is pre-decomposed. The pre-decomposed raw material enters the fifth-stage preheater 34, and after being collected, enters the smoke chamber 22, and then enters the rotary kiln 19. After being burned into clinker in the rotary kiln 19, the clinker enters the first cooling zone 27 of the grate cooler 18. The clinker passes through the first, second, and third cooling zones 29 of the grate cooler 18 in sequence, and after being cooled to the required temperature, it finally enters the clinker warehouse 17 for storage.

[0056] The circulating gas containing high concentration of carbon dioxide is output from the first stage preheater 30 when the temperature reaches 250-300℃, and is transported to the heat exchanger 3 through the high temperature fan 2 for cooling treatment. After cooling, the gas temperature drops to 160-180℃, and then it is dedusted by the dust collector 4 to ensure that the dust concentration is less than 10mg / m³. Part of the treated gas is sent to the raw gas purification system 5, and the other part re-enters the process through the circulating fan 6.

[0057] In the raw gas purification system 5, the circulating gas first passes through the absorption tower 35, where the activated carbon absorbs the sulfide in the circulating gas. Subsequently, the treated circulating gas is evenly mixed with CH4 from the methane (CH4) storage tank and then enters the selective catalytic reduction (SCR) device. The SCR device 36 is equipped with a CH4 catalyst, which exhibits a high catalytic efficiency at a temperature of about 500°C. In order to reach the required temperature, the SCR device 36 is heated by the flue gas discharged from the activated carbon regeneration tower 41 and electric heating, and the electricity required for electric heating comes from the wind power and photovoltaic power generation system.

[0058] Under the action of CH4 catalyst, the mixed gas of circulating gas and CH4 catalytically reduces all nitrogen oxides. After that, the gas enters the heat exchanger through the fan for cooling, and in the process, steam is generated for use. The flue gas after cooling is then passed through the pressure swing adsorption device 38 to remove part of the nitrogen (N2), and then enters the methanation device 45 through the fan.

[0059] The circulating gas treated by the circulating fan 6 has a carbon dioxide (CO2) dry basis concentration of more than 80%, and its flow is divided into two paths: the circulating gas in the first path continues to be recycled after some moisture is removed by the dehydration device 7; the circulating gas in the second path will enter the chimney 73 for discharge when needed, and remain closed during non-discharge periods.

[0060] After being treated by the dehydration device 7, the circulating gas temperature drops to 75-80°C, and then is divided into four paths. First, a part of the circulating gas is cooled to room temperature through the heat exchanger 2 8, and then supplied to the air compressor device 10, the conveying fan 13 and the coal powder conveying system 11 respectively. The second part of the circulating gas is directly conveyed to the sealing system 9. The third part is mixed with the high-concentration oxygen from the oxygen and gas production system 14 and enters the first cooling zone 27 of the grate cooler 18. The last part flows to the second cooling zone 28 of the grate cooler 18.

[0061] The compressed circulating gas processed by the air compressor device 10 is used as the air source of the dust cleaning system 12. The circulating gas after the conveying fan 13 is divided into two branches: one is mixed with the high-concentration oxygen from the oxygen production system 14 and then transported to the kiln tail burner 24; the other is also mixed with the high-concentration oxygen and then transported to the kiln head burner 20 as primary air. By adjusting the ratio of circulating gas to high-concentration oxygen, different states of combustion flames can be achieved.

[0062] The pulverized coal conveying system 11 uses circulating gas to pneumatically convey pulverized coal to the kiln tail burner 24 and the kiln head burner 20. The circulating gas entering the first cooling zone 27 of the grate cooler 18 exchanges heat with the clinker from the rotary kiln 19 and then enters the kiln head hood 21. The gas temperature in the kiln head hood 21 is between 950-1250°C, part of which returns to the rotary kiln 19 as secondary air, and the other part enters the decomposition furnace 23 as tertiary air. The circulating gas entering the second cooling zone 28 of the grate cooler 18 exchanges heat with the clinker from the first cooling zone 27, and the temperature drops to 400-500°C, and then enters the outlet of the decomposition furnace 23 for cooling and air replenishment. In the third cooling zone 29 of the grate cooler 18, the air exchanges heat with the clinker from the second cooling zone 28 to form hot air of 200-250°C, which is respectively sent to the raw material drying system 15 and the coal mill drying system 16.

[0063] Combination Figure 8In the oxygen-rich combustion process, since the raw meal is exposed to a high concentration of CO2 environment, in order to achieve the same decomposition rate as under air combustion conditions, the decomposition temperature of the raw meal in the decomposition furnace 23 needs to be increased by 80-100°C. In order to prevent the equipment from crusting, the decomposition furnace 23 is equipped with a kiln tail burner 24 with a pre-combustion chamber structure. The circulating gas carrying the coal powder first enters the pre-combustion chamber, where the oxygen excess coefficient in the pre-combustion chamber is maintained at 0.6. The coal powder is first gasified and pyrolyzed in the pre-combustion chamber, converted into combustible gases such as carbon monoxide, hydrogen and methane, and then these gases enter the decomposition furnace 23. A portion of the tertiary air is introduced, that is, the tertiary air is sprayed into the decomposition furnace 23 in an annular manner, which quickly surrounds and burns the combustible gas, effectively preventing the high-temperature crusting phenomenon on the side wall of the decomposition furnace 23.

[0064] In the kiln head sealing device 48, the circulating gas enters the isolation chamber 53 from the circulating gas inlet 1 54, and maintains a slight positive pressure of 5Pa in the isolation chamber 53. Part of the circulating gas enters the outside air through the gap of the sealing sheet 52, which prevents the outside air from entering the isolation chamber 53. The circulating gas entering from the circulating gas inlet 2 55 enters the cold air jacket to reduce the kiln head temperature, and then most of the gas is discharged through the circulating gas outlet 56, while a small part enters the system through the kiln head cover 21. In this way, the kiln head sealing device 48 effectively isolates the outside air and prevents it from entering the system.

[0065] As for the kiln tail sealing device 49, the rotating end of the compression seal rotates with the rotation of the rotary kiln 19, forming a double sealing structure of the fish scale sheet 60 and the friction pair 70. The circulating gas enters the sealing chamber 62 from the circulating gas inlet 3 68, and maintains a slight positive pressure of 5Pa in the sealing chamber 62. Part of the circulating gas passes through the gap of the sealing sheet 52 to enter the outside air, while the other part passes through the gap between the friction pair 70 of the compression seal structure to enter the smoke chamber 22. These measures ensure that the outside air cannot enter the sealing chamber 62, so that the kiln tail sealing device 49 successfully isolates the outside air and prevents it from entering the system.

[0066] The upper shed 64 of the dust collector 4 is designed as a closed structure to ensure that materials can only enter and exit through the double-layer inspection door 66 above the shed 64. The circulating air is introduced into the partition chamber 69 between the double-layer inspection doors 66 to maintain a slight positive pressure of 5Pa in the chamber. Due to the effect of the slight positive pressure, the outside air is effectively blocked and cannot enter the partition chamber 69, thereby protecting the dust collector 4 from the invasion of outside air. The lower part of the dust collector 4 is connected to the double-layer air lock valve 67, and the double-layer air lock valve 67 is connected to the connecting pipe between the third-stage preheater 32 and the second-stage preheater 31, which can effectively prevent the occurrence of air leakage problems. The cleaning gas used by the pulse cleaning device 65 comes from the circulating gas of the air compressor device 10, thereby preventing air from entering the system.

[0067] The wind-photovoltaic power generation system 43 and the external power grid jointly provide the required electric energy for the oxygen production device 39, the power-to-gas device 46 and the methanation device 45. By flexibly scheduling the output plan and energy allocation of each device, the oxygen and gas production system 14 can achieve low operating costs. Taking into account the peak and valley time periods as well as the wind energy and light intensity, the system will schedule the use of electric energy from the external power grid and the wind-photovoltaic power generation system 43, giving priority to the use of wind-photovoltaic power generation.

[0068] The oxygen (O2) produced by the oxygen production device 39 will be stored in the oxygen storage tank 47, or directly transported to the kiln head burner 20, the kiln tail burner 24, the hot air device 40 and the first cooling zone 27 of the grate cooler 18 for use. The power-to-gas device 46 produces oxygen and hydrogen (O2 and H2) by electrolyzing water, wherein the oxygen is also stored or directly transported to the above-mentioned burners and cooling zones. The hydrogen enters the methanation device 45 together with the high-concentration carbon dioxide (CO2) from the raw gas purification system 5, and a methanation reaction occurs under the action of a methane catalyst to generate methane (CH4), which is stored in the CH4 storage tank 44 (the reaction equation is: CO2+4H2→CH4+2H2O).

[0069] The oxygen storage tank 47 enables oxygen to be used across different time periods. When the wind power and photovoltaic power generation systems generate sufficient electricity, the generated electricity will drive the oxygen production equipment and the power-to-gas equipment to produce oxygen (O2). Part of the produced oxygen is transported to the kiln head burner 20, the kiln tail burner 24, the hot air device 40 and the first cooling zone 27 of the grate cooler 18 for use, while the excess oxygen is stored in the oxygen storage tank 47. On the contrary, when the wind power and photovoltaic power generation systems generate insufficient electricity to meet the system's oxygen-rich operation requirements, the oxygen in the oxygen storage tank 47 will be used to supplement the shortfall. If there is still an oxygen gap, the external power grid will be enabled to supplement the power supply and oxygen production.

[0070] The CH4 storage tank 44 ensures the use of methane (CH4) across time periods. A portion of the methane stored in the CH4 storage tank 44 is stably supplied to the kiln tail burner 24 as auxiliary fuel to reduce the consumption of coal powder; a portion is supplied to the hot air device 40 as fuel to provide heat; another portion is transported to the outlet of the smoke chamber 22 as a denitrification reducing agent to remove most of the nitrogen oxides; the remaining portion is transported to the selective catalytic reduction (SCR) device to remove secondary nitrogen oxides to prevent methane catalyst poisoning.

[0071] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A system for producing cement clinker by coupling oxygen-enriched combustion with green energy, characterized in that: A system or device including the following pipe connections: Clinker burning system (1), high temperature fan (2), heat exchanger 1 (3), dust collector (4), raw gas purification system (5), circulating fan (6), water removal device (7), heat exchanger 2 (8), sealing system (9), air compressor device (10), pulverized coal conveying system (11), ash cleaning system (12), conveying fan (13), oxygen and gas production system (14), raw material drying system (15), coal mill drying system (16), clinker storage (17); The clinker burning system (1) comprises a grate cooler (18), a rotary kiln (19), a kiln head burner (20), a kiln head cover (21), a smoke chamber (22), a decomposition furnace (23), a kiln tail burner (24), preheaters (25) of various stages and a pressure reamer (26); wherein the grate cooler (18) is divided into three cooling zones, namely a first cooling zone (27), a second cooling zone (28) and a third cooling zone (29) which are connected in sequence; the preheaters (25) of various stages are divided into first to fifth stage preheaters (34), and the first stage preheater (30) to the fifth stage preheater (34) are connected in sequence; The pressure reamer (26) is connected to the connecting pipe between the second-stage preheater (31) and the first-stage preheater (30); the fifth-stage preheater (34) is connected to the decomposition furnace (23); the kiln tail burner (24) is arranged on the decomposition furnace (23); the decomposition furnace (23) is connected to the smoke chamber (22); the smoke chamber (22) is connected to one end of the rotary kiln (19); the other end of the rotary kiln (19) is connected to the kiln head cover (21) and the first cooling zone (27); the kiln head burner (20) is arranged on the kiln head cover (21); the kiln head cover (21) is connected to the first cooling zone (27) and the decomposition furnace (23); The first-stage preheater (30), the high-temperature fan (2), the heat exchanger 1 (3), the dust collector (4) and the circulating fan (6) are connected in sequence; the dust collector (4) is respectively connected to the raw gas purification system (5) and the circulating fan (6); the circulating fan (6) is respectively connected to the water removal device (7) and the chimney (73); the water removal device (7) is respectively connected to the heat exchanger 2 (8), the sealing system (9), the first cooling zone (27) and the second cooling zone (28); The second heat exchanger (8) is respectively connected to the air compressor device (10), the conveying fan (13) and the pulverized coal conveying system (11); the air compressor device (10) is connected to the ash cleaning system (12); the conveying fan (13) is respectively connected to the kiln head burner (20) and the kiln tail burner (24); the pulverized coal conveying system (11) is respectively connected to the kiln head burner (20) and the kiln tail burner (24); the second cooling zone (28) is connected to the connecting pipeline between the decomposition furnace (23) and the fifth stage preheater (34); the third cooling zone (29) is respectively connected to the raw material drying system (15) and the coal mill drying system (16); The raw gas purification system (5) comprises an absorption tower (35), an SCR device (36), a heat exchanger (37), a pressure swing adsorption device (38), an exhaust fan, a hot air device (40), a regeneration tower (41) and a sulfur recovery device (42); The oxygen and gas production system (14) comprises a wind-photovoltaic power generation system (43), a CH4 storage tank (44), a methanation device (45), an electric-to-gas device (46), an oxygen storage tank (47) and an oxygen production device (39); the wind-photovoltaic power generation system (43) is respectively connected to the electric-to-gas device (46), the methanation device (45) and the oxygen production device (39); the oxygen production device (39) is respectively connected to the oxygen storage tank (47) and the kiln head burner (20), the kiln tail burner (24) and the first cooling zone (27); The oxygen storage tank (47) is respectively connected to the kiln head burner (20), the kiln tail burner (24) and the first cooling zone (27); the electric-to-gas device (46) is respectively connected to the oxygen storage tank (47), the methanation device (45), the kiln head burner (20), the kiln tail burner (24), the CH4 storage tank (44) and the raw gas purification system (5); the CH4 storage tank (44) is connected to the kiln tail burner (24), the SCR device (36), the hot air device (40) and the outlet of the smoke chamber (22); The outlet of the decomposition furnace (23) is provided with a flue gas analysis device (71), and the flue gas analysis device (71) is used to calculate the nitrogen oxide content and CaO content at the outlet of the decomposition furnace (23). A methane denitrifier (72) is provided at the outlet of the smoke chamber (22).

2. The system for producing cement clinker by coupling oxygen-enriched combustion with green energy according to claim 1 is characterized in that: The sealing system (9) includes a kiln head sealing device (48), a kiln tail sealing device (49) and improved inspection doors, valves, holes and covers at various locations in the system; the sealing system (9) also includes a pipeline system connecting various sealing points.

3. The system for producing cement clinker by coupling oxygen-enriched combustion with green energy according to claim 2 is characterized in that: The kiln head sealing device (48) adopts a double-layer fish scale sealing structure.

4. The system for producing cement clinker by coupling oxygen-enriched combustion with green energy according to claim 3 is characterized in that: The kiln head sealing device (48) comprises a friction ring (50), a sealing cover (51) and a plurality of sealing sheets (52); the friction ring (50) is arranged on the outer side wall of the rotary kiln (19); the sealing cover (51) is connected to the kiln head cover (21); each of the sealing sheets (52) is stacked to form a double-layer fish scale-shaped annular cover body; one end of the annular cover body is pressed on the friction ring (50) and the other end is fixed on the sealing cover (51); each of the sealing sheets (52), the friction ring (50) and the sealing cover (51) enclose an isolation chamber (53); wherein the sealing cover (51) is provided with a first circulating gas inlet (54), a second circulating gas inlet (55) and a circulating gas outlet (56).

5. The system for producing cement clinker by coupling oxygen-enriched combustion with green energy according to claim 2, characterized in that: The kiln tail sealing device (49) adopts a double-layer sealing structure of compression sealing and fish scale sealing.

6. The system for producing cement clinker by coupling oxygen-enriched combustion with green energy according to claim 5, characterized in that: The kiln tail sealing device (49) comprises a compression seal fixed end (57), a compression seal rotating end (58), an isolation cover (59), a plurality of fish scales (60) and a contact ring (61); the contact parts of the compression seal fixed end (57) and the compression seal rotating end (58) form a friction pair (70) to constitute a compression seal structure; the isolation cover (59) is arranged on the side wall of the smoke chamber (22); each of the fish scales (60) is stacked into a fish scale-shaped annular cover body, and one end is fixed on the isolation cover (59) and the other end is pressed on the contact ring (61); the contact ring (61) is arranged on the compression seal rotating end (58); the isolation cover (59), the fish scales (60), the contact ring (61), the compression seal fixed end (57) and the compression seal rotating end (58) together form a sealing cavity (62).

7. The system for producing cement clinker by coupling oxygen-enriched combustion with green energy according to claim 1, characterized in that: The dust collector (4) adopts a high-box shed (64) structure, comprising a shell (63), a shed (64), a pulse dust cleaning device (65), a double-layer inspection door (66) and an air lock valve (67); the shed (64) is a closed structure and is arranged on the upper part of the shell (63); a plurality of double-layer inspection doors (66) are arranged on the shed (64); a closed partition chamber (69) is formed in the middle of the double-layer inspection doors (66); and the air lock valve (67) is arranged at the lower part of the shell (63).

8. The system for producing cement clinker by coupling oxygen-enriched combustion with green energy according to claim 7, characterized in that: The dust cleaning system (12) comprises an air cannon, a pulse dust cleaning device (65), and a pipeline system connecting various dust cleaning points.

9. A method for producing cement clinker by using the system of oxygen-enriched combustion coupled with green energy as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1, the raw material is input into the connecting pipe of the first stage preheater (30) and the second stage preheater (31) through the pressure reamer (26), and heat exchange is carried out with the circulating gas rich in high concentration of CO2 in the pipe, and then enters the first stage preheater (30) along with the circulating gas; S2, the raw meal in the circulating gas is collected by the first stage preheater (30) and enters the connecting pipe between the third stage preheater (32) and the second stage preheater (31), and then enters the second stage preheater (31) after heat exchange with the circulating gas therein. The raw meal then enters the decomposition furnace (23) after heat exchange with the circulating gas in the second to fourth stage preheaters in sequence; S3, the raw material is pre-decomposed in the decomposition furnace (23) and then enters the fifth-stage preheater (34). After being collected by the fifth-stage preheater (34), it enters the smoke chamber (22), and then enters the rotary kiln (19). After being burned into clinker in the rotary kiln (19), the raw material enters the grate cooler (18) for cooling. After being cooled to the required temperature, the raw material enters the clinker storage (17) for storage; The circulating gas containing high concentration of carbon dioxide is output from the first stage preheater (30) and transported to the first heat exchanger (3) through the high temperature fan (2) for cooling treatment; part of the treated gas is sent to the raw gas purification system (5), and the other part re-enters the process through the circulating fan (6); In the raw gas purification system (5), the circulating gas first passes through an absorption tower (35), and the absorption tower (35) absorbs sulfides in the circulating gas. The treated circulating gas is mixed with CH4 from a CH4 storage tank (44) and then enters a selective SCR device (36). The SCR device (36) is equipped with a CH4 catalyst. The SCR device (36) is heated by flue gas discharged from an activated carbon regeneration tower (41) and electric heating. The electricity required for the electric heating comes from a wind-photovoltaic power generation system (43). Under the action of the CH4 catalyst, the mixed gas of the circulating gas and CH4 catalytically reduces all nitrogen oxides; then, the gas enters the heat exchanger through the fan for cooling, and in the process, steam is generated for use; the flue gas after cooling is then passed through the pressure swing adsorption device (38) to remove part of the nitrogen, and then enters the methanation device (45) through the fan; The circulating gas processed by the circulating fan (6) flows in two paths: the circulating gas in the first path passes through the dehumidification device (7) to remove some moisture and then continues to be circulated; the circulating gas in the second path enters the chimney (73) for discharge when needed, and remains closed during non-discharge periods; After being processed by the water removal device (7), the circulating gas temperature drops and is divided into four paths: first, a part of the circulating gas is cooled to room temperature through the second heat exchanger (8), and then supplied to the air compressor device (10), the conveying fan (13) and the coal powder conveying system (11); the second part of the circulating gas is directly conveyed to the sealing system (9); the third part is mixed with the high-concentration oxygen from the oxygen and gas production system (14) and enters the first cooling zone (27) of the grate cooler (18); and the last part flows to the second cooling zone (28) of the grate cooler (18); The compressed circulating air processed by the air compressor device (10) is used as the air source of the dust cleaning system (12); the circulating air after the conveying fan (13) is divided into two branches: one branch is mixed with high-concentration oxygen from the oxygen production system (14) and then transported to the kiln tail burner (24); the other branch is also mixed with high-concentration oxygen and then transported as primary air to the kiln head burner (20); The pulverized coal conveying system (11) uses circulating gas to pneumatically convey the pulverized coal to the kiln tail burner (24) and the kiln head burner (20); the circulating gas entering the first cooling zone (27) of the grate cooler (18) exchanges heat with the clinker from the rotary kiln (19) and then enters the kiln head cover (21); a portion of the gas in the kiln head cover (21) returns to the rotary kiln (19) as secondary air, and the other portion enters the decomposition furnace (23) as tertiary air; the circulating gas entering the second cooling zone (28) of the grate cooler (18) exchanges heat with the clinker from the first cooling zone (27), and after the temperature drops, enters the outlet of the decomposition furnace (23) for cooling and air replenishment; in the third cooling zone (29) of the grate cooler (18), the air exchanges heat with the clinker from the second cooling zone (28) to form hot air, which is respectively sent to the raw material drying system (15) and the coal mill drying system (16); The wind-photovoltaic power generation system (43) and the external power grid jointly provide the required electric energy for the oxygen production device (39), the power-to-gas device (46) and the methanogenization device (45); By flexibly scheduling the output plan and energy allocation of each device, the oxygen and gas production system (14) can achieve low operating costs; taking into account the peak and valley periods as well as the wind energy and light intensity, the system will schedule the use of electricity from the external power grid and the wind-photovoltaic power generation system (43), giving priority to the use of wind-photovoltaic power generation; The oxygen produced by the oxygen production device (39) is stored in an oxygen storage tank (47) or directly transported to the kiln head burner (20), the kiln tail burner (24), the hot air device (40) and the first cooling zone (27) of the grate cooler (18) for use; the power-to-gas device (46) generates oxygen and hydrogen by electrolyzing water, wherein the oxygen is also stored or directly transported to the above-mentioned burner and cooling zone; the hydrogen enters the methanation device (45) together with the high-concentration carbon dioxide from the raw gas purification system (5), undergoes a methanation reaction under the action of a methane catalyst, generates methane, and is stored in the CH4 storage tank (44); The oxygen storage tank (47) enables oxygen to be used across different time periods. When the wind power and photovoltaic power generation systems generate sufficient electricity, the generated electricity will drive the oxygen production equipment and the power-to-gas equipment to produce oxygen; part of the produced oxygen is transported to the kiln head burner (20), the kiln tail burner (24), the hot air device (40) and the first cooling zone (27) of the grate cooler (18) for use, while the excess oxygen is stored in the oxygen storage tank (47); on the contrary, when the wind power and photovoltaic power generation systems generate insufficient electricity to meet the system's oxygen-rich operation requirements, the oxygen in the oxygen storage tank (47) will be used to supplement the shortfall; if there is still an oxygen gap, the external power grid will be enabled to supplement the power supply for oxygen production; The CH4 storage tank (44) ensures the use of methane across time periods. A portion of the methane stored in the CH4 storage tank (44) is stably supplied to the kiln tail burner (24) as auxiliary fuel to reduce the consumption of coal powder; a portion is supplied to the hot air device (40) as fuel to provide heat; another portion is transported to the outlet of the smoke chamber (22) as a denitrification reducing agent to remove most of the nitrogen oxides; and the remaining portion is transported to the selective SCR device (36) to remove secondary nitrogen oxides to prevent methane catalyst poisoning.

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