System and method for green hydrogen-green ammonia fuel calcined cement clinker

Abstract

The application discloses a system and method for calcining cement clinker by using green hydrogen and green ammonia fuel, which comprises a preheating subsystem, a calcining subsystem, a cooling subsystem, a distributed photovoltaic power station subsystem, a water electrolysis subsystem, an ammonia synthesis subsystem and a water-vapor separation subsystem. The distributed photovoltaic power station subsystem is connected with the water electrolysis subsystem to deliver electric energy, the water electrolysis subsystem is connected with the ammonia synthesis subsystem to deliver green hydrogen, and the green hydrogen is connected with the calcining subsystem and the cooling subsystem to deliver green oxygen as a combustion-supporting agent of a rotary kiln and cooling air of a grate cooler. The water-vapor separation subsystem is connected with the preheating subsystem and the water electrolysis subsystem to recover water and CO2 in hot flue gas. Oxygen generated by photovoltaic power generation and water electrolysis is used as a combustion-supporting agent of oxygen-rich combustion of the rotary kiln or cooling air of the grate cooler, and green hydrogen is used for synthesizing ammonia, and green hydrogen and / or green ammonia are introduced into a decomposition furnace to replace coal. The application can realize long-term steady-state operation of a sintering system, and the prepared CO2 has high purity.

Description

TECHNICAL FIELD

[0001] The present application relates to a system and method for calcining cement, in particular to a system and method for calcining cement clinker with green hydrogen-green ammonia fuel. BACKGROUND

[0002] Hydrogen energy, as a clean, efficient and sustainable secondary energy, can be obtained through various ways. Hydrogen energy can be easily coupled with electricity, heat and fuel, and together with electricity, it can establish a modern energy network, significantly increasing the flexibility of the power network. It is of great significance to carry out research on hydrogen energy to replace coal-fired cement clinker production technology for carbon emission reduction in the cement industry.

[0003] Currently, due to the limitations of preparation cost, economic benefit and hydrogen safety, it is not realistic to completely replace coal with hydrogen as fuel for cement kiln. Green hydrogen and nitrogen are used to synthesize green ammonia, which is an important way to prepare green ammonia. Compared with hydrogen, ammonia is safer in terms of explosion prevention; ammonia is easy to store and transport and has good explosion-proof characteristics; the infrastructure for ammonia is more complete. However, the low heating value of ammonia is slightly lower than that of traditional fuels (such as gasoline, diesel and ethanol), the minimum ignition energy required for combustion is higher, the flame propagation speed is slower, and nitrogen oxides are difficult to control.

[0004] In order to make the reaction of generating C3S more complete and obtain higher yield, the fuel burning in the rotary kiln should meet certain requirements: the flame temperature of fuel burning should reach 1600-1800℃; in order to maintain the high temperature of the material, the flame should have appropriate length. When hydrogen fuel is used for burning, although hydrogen fuel can burn more cleanly, the emission of NO x may increase. When hydrogen is burned, the flame is small and the flame radiation heat is low, which will interfere with the clinker burning process. When ammonia is burned, the laminar flame speed, self-ignition temperature and adiabatic flame temperature are all lower than those of hydrogen and methane, making it difficult to ignite, the oxidation process is mild, the combustion is unstable and the reaction activity is poor. The stability of the thermal system of the rotary kiln is the fundamental guarantee of the quality of clinker calcination. When hydrogen and ammonia are used as fuel for the rotary kiln, it may cause thermal fluctuations, and the proportion of coal used in the rotary kiln and the decomposing furnace is about 4:6, and the amount of coal used in the rotary kiln is less than that in the decomposing furnace.

[0005] Therefore, green hydrogen-green ammonia is preferred as fuel for the decomposing furnace to reduce the disturbance and fluctuation of the rotary kiln operating conditions. Through technology integration, process technology adjustment and thermal system optimization, the long-term steady-state operation of the firing system is ensured, and the proportion of coal use is reduced. SUMMARY

[0006] Purpose of the invention: The purpose of this invention is to provide a system for calcining cement clinker with green hydrogen-green ammonia fuel that can fully utilize the green hydrogen and oxygen generated by water electrolysis in cement plants, achieve a continuous supply of hydrogen for cement clinker calcination, and ensure the stability of the rotary kiln thermal regime.

[0007] A second objective of this invention is to provide a method for calcining cement clinker using the system described above.

[0008] Technical solution: The green hydrogen-green ammonia fuel calcination cement clinker system of the present invention includes a preheating subsystem, a calcination subsystem and a cooling subsystem, as well as a distributed photovoltaic power station subsystem, an electrolysis water subsystem, a synthetic ammonia subsystem and a water vapor separation subsystem;

[0009] The power supply outlet of the distributed photovoltaic power station subsystem is connected to the power supply inlet of the water electrolysis subsystem;

[0010] The water electrolysis subsystem includes a water electrolyzer, a hydrogen storage tank connected to the hydrogen outlet of the water electrolyzer, an oxygen storage tank connected to the oxygen outlet of the water electrolyzer, and a makeup water storage tank connected to the water inlet of the water electrolyzer; the oxygen storage tank is connected to the combustion aid inlet of the rotary kiln for oxygen-enriched combustion and the cooling air inlet of the fixed bed in the grate cooler; the hydrogen storage tank is connected to the hydrogen fuel inlet of the decomposition furnace and the hydrogen inlet of the ammonia synthesis subsystem.

[0011] The ammonia synthesis subsystem is also equipped with a nitrogen inlet and an ammonia outlet, and the ammonia outlet is connected to the ammonia fuel inlet of the decomposition furnace.

[0012] The flue gas inlet of the water vapor separation subsystem is connected to the flue gas outlet of the preheating subsystem, the liquid outlet is connected to the water inlet of the water electrolysis cell, and the flue gas outlet is connected to the inlet of the carbon dioxide storage tank.

[0013] The water vapor separation subsystem includes a water vapor separator connected to the flue gas outlet of the preheating subsystem, a condenser connected to the water vapor separator, a carbon dioxide storage tank inlet connected to the gas outlet of the condenser, and a condensate tank connected to the liquid outlet of the condenser; the condensate tank is connected to the water inlet of the water electrolysis cell.

[0014] The ammonia synthesis subsystem includes an ammonia synthesis tower. The hydrogen inlet of the ammonia synthesis tower is connected to the hydrogen storage tank of the water electrolysis subsystem, the nitrogen inlet is connected to the nitrogen pipeline, and the ammonia outlet is connected to the ammonia fuel inlet of the decomposition furnace.

[0015] The calcination subsystem includes a decomposition furnace, a first burner located at the bottom of the decomposition furnace, a second burner and a third burner located above the first burner, a rotary kiln, and a fourth burner located at the kiln head of the rotary kiln; the gas outlet of the hydrogen storage tank is connected to the gas inlet of the first burner and the hydrogen inlet of the ammonia synthesis subsystem, respectively.

[0016] The method for calcining cement clinker using the above-described system includes the following steps:

[0017] (A) The distributed photovoltaic power station subsystem inputs electrical energy into the water electrolysis subsystem. After water is electrolyzed, green hydrogen and oxygen are produced. The green hydrogen and nitrogen separated from the air are then introduced into the ammonia synthesis subsystem to produce green ammonia.

[0018] (B) Green hydrogen-green ammonia is introduced into the decomposition furnace to replace part or all of the fuel coal in the decomposition furnace, providing a heat source for the decomposition of raw materials; oxygen produced by electrolysis of water is used as an aid for oxygen-enriched combustion in the rotary kiln and as cooling air for the fixed bed in the grate cooler.

[0019] (C) The flue gas discharged from the raw material mill is purified and dust collected, and then separated into water vapor and CO2 by a water vapor separation system. The separated water vapor is condensed and returned to the electrolyzed water for recycling.

[0020] The green hydrogen and green ammonia are introduced into the lower part of the decomposition furnace individually or simultaneously.

[0021] When the green hydrogen and green ammonia replace 5% to 20% of the fuel coal in the decomposition furnace, they are introduced into the space between the upper part of the flue gas chamber constriction and the decomposition furnace; when the green hydrogen and green ammonia replace 20% to 100% of the fuel coal in the decomposition furnace, they are introduced into the air inlet of the tertiary air duct at the lower part of the decomposition furnace, which is level with or close to the upper area.

[0022] When green hydrogen and green ammonia replace the fuel coal in the decomposition furnace, hydrogen is set up with a separate burner; ammonia is set up with a separate burner or is blended into the fuel coal; preferably, swirl burners are used; the hydrogen burner is arranged below the ammonia burner or the ammonia-coal dual-fuel burner.

[0023] In this process, ammonia is co-fired into the fuel coal. The ammonia enters the decomposition furnace through the central airflow, while the pulverized coal enters the decomposition furnace through the annular nozzle. Air enters the decomposition furnace through the swirl blades to form a rotating airflow.

[0024] Of the oxygen produced by water electrolysis, 5% to 50% is used as an aid for oxygen-enriched combustion in the rotary kiln, and the remainder is used as cooling air for the grate cooler, which is introduced from the cooling air inlet of the fixed bed of the grate cooler.

[0025] The carbon dioxide concentration at the outlet of the water vapor separator is between 35 vol.% and 60 vol.%.

[0026] The photovoltaic power station for producing hydrogen through water electrolysis is a distributed photovoltaic power station located in or around a cement plant area where solar energy resources are abundant.

[0027] The electrolyzed water used to supply green hydrogen to the decomposition furnace is preferably powered by a distributed photovoltaic power station located in the cement plant area.

[0028] The electrolytic water used to provide green hydrogen for the synthesis of green ammonia is preferably powered by a distributed photovoltaic power station near the cement plant, which has abundant solar energy resources.

[0029] The distributed photovoltaic power stations located within the cement plant area are situated in open spaces, plant rooftops, water tanks, conveyor belts, and mines, with an installed capacity of 5-15MW. Preferably, the rooftops of gypsum storage sheds, raw coal storage sheds, pre-homogenization yards for mixed materials, and pre-homogenization yards for limestone are used.

[0030] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0031] 1. This invention utilizes the abundant solar energy resources of distributed photovoltaic power stations in and around cement plants, rationally configuring power supply according to the actual production conditions of the cement plant to achieve a stable supply of hydrogen produced through water electrolysis. Simultaneously, it economically and rationally utilizes the oxygen generated from water electrolysis on-site, using it as a combustion aid in the oxygen-enriched combustion of the rotary kiln or as cooling air in the grate cooler, thus improving the combustion process in the cement kiln and correspondingly reducing the system's heat consumption. Therefore, this invention maximizes the utilization of clean energy within the cement enterprise area, achieves a continuous supply of hydrogen for cement clinker calcination, and ensures the stability of the rotary kiln's thermal regime.

[0032] 2. Based on the actual conditions of photovoltaic power generation and cement plant sites, this invention allows green hydrogen or green ammonia to be introduced into the lower part of the decomposition furnace either alone or simultaneously to replace coal. Hydrogen-infused combustion in the decomposition furnace increases the flame combustion rate, accelerates the combustion process, reduces flue gas emissions, lowers CO and CO2 emissions, and increases water vapor generation. Ammonia combustion is difficult to ignite and has poor stability, resulting in low fuel combustion efficiency. When green hydrogen and green ammonia are introduced into the decomposition furnace simultaneously, the hydrogen promotes the ignition and combustion of ammonia, optimizing the ammonia combustion process. This operation is flexible and facilitates system adjustment and optimization.

[0033] 3. This invention rationally allocates the fuel ratio at the kiln tail and rationally sets up burners in the decomposition furnace. The calcination temperature of hydrogen and ammonia is adjusted through the burners, thereby controlling the combustion rate of the decomposition furnace. By adjusting key technical issues such as the control of hydrogen flame shape and flame temperature, and solving technical issues such as heat balance, the stable and long-term stable operation of the rotary kiln's thermal regime is achieved.

[0034] 4. This invention utilizes green hydrogen and green ammonia to replace the fuel in the decomposition furnace, effectively reducing fossil fuel consumption and improving energy efficiency. The flue gas consists almost entirely of CO2 and water vapor. The water vapor can be easily removed through dehydration to obtain a high concentration of CO2, significantly reducing the cost of carbon capture and providing the possibility for subsequent carbon dioxide replenishment and utilization. The water recovered from the system's condensation is used as a water source for water electrolysis, conserving resources.

[0035] 5. This invention economically and rationally maximizes the utilization of clean energy within the cement plant area, achieving a continuous supply of hydrogen for cement clinker calcination, thus providing significant social and economic benefits. The subsystems are rationally designed, providing a system for calcining cement clinker using green hydrogen-green ammonia fuel, characterized by good gas-solid contact, smooth material flow, and high thermal efficiency. Attached Figure Description

[0036] Fig. 1 This is a schematic diagram of the system structure of the present invention;

[0037] Fig. 2 This is a schematic diagram of the burner distribution in the air inlet or upper region of the tertiary air duct of the present invention.

[0038] Fig. 3 This is a schematic diagram of the decomposition furnace and various burners of the present invention. Detailed Implementation

[0039] The present invention will now be described in further detail.

[0040] Example 1

[0041] like Figs. 1-3 As shown, the system for calcining cement clinker using green hydrogen / green ammonia fuel of the present invention includes a first cyclone 1, a second cyclone 2, a third cyclone 3, a fourth cyclone 4, a fifth cyclone 5, a decomposition furnace 6, a rotary kiln 7, a grate cooler 8, a waste heat power generation system 9, a raw material mill 10, a high-temperature fan 11, a dust collector 12, a water vapor separator 13, a condenser 14, a carbon dioxide storage tank 15, a condensate tank 16, a distributed photovoltaic power station 17, a makeup water storage tank 18, a water electrolyzer 19, a hydrogen storage tank 20, an oxygen storage tank 21, and a synthetic ammonia tower 22. The first cyclone 1, the second cyclone 2, the third cyclone 3, the fourth cyclone 4, the waste heat power generation system 9, the raw material mill 10, the high-temperature fan 11, and the dust collector 12, from top to bottom, constitute a preheating subsystem to achieve four-stage heat exchange; the fifth cyclone 5, the decomposition furnace 6, and the first burner 601, the second burner 602, the third burner 603 installed on the decomposition furnace 6, the rotary kiln 7, and the fourth burner 604 installed at the kiln head of the rotary kiln constitute a calcination subsystem to achieve high-temperature calcination and gas-solid separation of the raw material after calcination; the grate cooler 8 constitutes a cooling subsystem to cool the calcined clinker.

[0042] The water electrolysis subsystem includes a water electrolyzer 19, a hydrogen storage tank 20, an oxygen storage tank 21, and a makeup water storage tank 18; the water vapor separation subsystem includes a water vapor separator 13, a condenser 14, a carbon dioxide storage tank 15, and a condensate tank 16. The ammonia synthesis subsystem includes an ammonia synthesis tower 22, in which green hydrogen is separated from nitrogen by air to synthesize green ammonia.

[0043] The connection relationships of the components in the system of this embodiment are as follows:

[0044] The gas inlet of the first cyclone 1 is connected to the gas outlet of the second cyclone 2 via a pipe; the gas outlet of the third cyclone 3 is connected to the gas inlet of the second cyclone 2 via a pipe, and the gas inlet of the third cyclone 3 is connected to the gas outlet of the fourth cyclone 4 via a pipe; the gas inlet of the fourth cyclone 4 is connected to the gas outlet of the fifth cyclone 5 via a pipe. The gas outlet of the decomposition furnace 6 is connected to the gas inlet of the fifth cyclone 5 via a pipe; the gas inlet of the decomposition furnace 6 is connected to the gas outlet of the fifth cyclone 5 via a pipe; the gas outlet of the first cyclone 1 is connected to the inlet of the waste heat power generation system 9; the outlet of the waste heat power generation system 9 is connected to the inlet of the raw material mill 10; the dust collector 12 is connected to both the raw material mill 10 and the water vapor separator 13; the outlet of the water vapor separator 13 is connected to the inlet of the condenser 14, the gas outlet of the condenser 14 is connected to the inlet of the carbon dioxide storage tank 15, and the condensate outlet of the condenser 14 is connected to the condensate tank 16; the condensate... The outlet of tank 16 is connected to the water inlet of water electrolysis cell 19; the power supply outlet of distributed photovoltaic power station 17 is connected to the power supply inlet of water electrolysis cell 19 to input electrical energy for water electrolysis; the gas outlet of water electrolysis cell 19 is connected to two parallel branches, which are respectively connected to hydrogen storage tank 20 and oxygen storage tank 21; the gas outlet of hydrogen storage tank 20 is connected to two parallel branches, which are respectively connected to the gas inlet of first burner 601 and the hydrogen inlet of ammonia synthesis tower 22; the gas outlet of oxygen storage tank 21 is connected to two parallel branches, which are respectively connected to the gas inlet of fourth burner 604 and the cooling air inlet of fixed bed in grate cooler 8. The nitrogen inlet of ammonia synthesis tower 22 is connected to the nitrogen pipeline of air separation, and the ammonia outlet of ammonia synthesis tower is connected to the ammonia fuel inlet of decomposition furnace 6.

[0045] When hydrogen is burned as fuel, the ambient temperature will be very high. Therefore, 2 to 4 first burners 601 can be configured, and 1 to 2 second burners 602 and third burners 603 can be configured. In this embodiment of the invention, the dust collector, cyclone separator, flap valve, and other equipment are all existing equipment, and their structures will not be described in detail. The dust collector can be an electrostatic precipitator or a bag filter, and the flap valve can be a weighted flap valve.

[0046] Another aspect of this invention provides a method for calcining cement clinker using green hydrogen / green ammonia fuel, which mainly includes the following steps:

[0047] (1) Cement raw materials are added to the preheating subsystem. After the preheating subsystem completes four-stage heat exchange, they enter the calcination subsystem for calcination. The calcined cement raw materials are then calcined in a rotary kiln and cooled to become cement clinker.

[0048] (2) The photovoltaic power station provides electrical energy for water electrolysis, and the water electrolysis device produces green hydrogen and oxygen; some of the green hydrogen and nitrogen separated from the air are used to prepare green ammonia in the ammonia synthesis tower;

[0049] (3) Green hydrogen-green ammonia is introduced separately into the lower part of the decomposition furnace to replace the fuel coal, or simultaneously into the decomposition furnace fuel to provide a heat source for the decomposition of raw materials; the oxygen generated by water electrolysis is used as an aid for oxygen-enriched combustion in the rotary kiln to enhance combustion in the kiln.

[0050] The system flue gas consists almost entirely of CO2 and water vapor. Water vapor is easily removed through dehydration to obtain a high concentration of CO2. Because a carbon dioxide atmosphere affects calcium carbonate decomposition, increasing the carbonate decomposition temperature by 50°C to 100°C and significantly increasing system heat consumption, the system flue gas is not recycled as cooling air for the grate cooler. Instead, the remaining oxygen from water electrolysis is used as cooling air for the grate cooler, entering through the fixed-bed cooling air inlet within the grate cooler. This portion of the flue gas is more easily used as secondary and tertiary air in the system. After heat exchange with the raw material, the flue gas enters the waste heat power generation system 9 through a pipe from the first cyclone separator 1 to recover heat, then enters the raw material mill 10 to dry the raw material. The flue gas discharged from the raw material mill 10 is purified by the dust collector 12. The water separated by the water vapor separator 13 is condensed by the condenser 14 and returned to the water electrolysis cell 19 for recycling. The water replenishment tank 18 replenishes a certain amount of water to the water electrolysis cell. The CO2 separated from the condenser 14 enters the carbon dioxide storage tank for later use. The preparation method of the present invention will be described in detail below with specific examples.

[0051] Currently, the vast majority of hydrogen is produced from fossil fuels, with a single alkaline electrolyzer producing approximately 1000~1500 Nm³ of hydrogen. 3 / h, unit power consumption is 4.2~4.6 kWh / Nm 3 The lower heating value of hydrogen is 2580 kJ / Nm³. 3 A 5000t / d clinker production line uses approximately 32t / h of raw coal with a raw coal content of 5500kcal / kg. Therefore, if pure hydrogen were to completely replace coal, approximately 60000 Nm³ of hydrogen would be required. 3 To produce hydrogen per hour, approximately 36,000 Nm³ of hydrogen is needed to replace coal at the entire kiln tail. 3 Hydrogen gas production is [amount] / h, with a byproduct of approximately 18,000 Nm³. 3 The oxygen production capacity is approximately 1 / h. Currently, most cement plants are existing production lines with limited space. Cement plants generate significant amounts of dust, including raw material dust, clinker dust, and cement dust. It is necessary to avoid areas with severe dust emissions, such as the rooftops of gypsum storage silos, raw coal storage sheds, pre-homogenization yards for mixed materials, and limestone pre-homogenization yards, and utilize rooftop photovoltaic power generation to produce renewable energy. A 5000t / d clinker production line typically has a photovoltaic power generation capacity of 2-5MW, and the hydrogen production from photovoltaic power generation within the plant area, such as gypsum storage silos, is approximately 500-1500 Nm³. 3 / h, oxygen production is approximately 250~750 Nm³ 3 The flue gas volume of a 5000t / d clinker production line is approximately 87800 Nm³ / h.3 / h, the primary air volume at the kiln head accounts for approximately 10% of the total air volume, which is 8800 Nm. 3 / h. Therefore, oxygen produced by electrolyzing water using photovoltaic power generation in the gypsum joint storage facility and other plant areas is supplied to the fourth burner 604. The oxygen, along with the primary air, enters the combustion chamber, enhancing combustion within the kiln and improving clinker quality and yield. Distributed rooftop photovoltaic power stations with installed capacities of 5-15MW are deployed in open spaces, factory rooftops, water tanks, conveyor belts, and mines within the cement plant area, producing approximately 1500-4500 Nm³ of hydrogen. 3 / h, oxygen production is approximately 750~2250 Nm³ 3 / h. At this time, the hydrogen produced by the water electrolysis device is introduced into the first burner 601, and the oxygen is supplied to the fourth burner 604. When a distributed photovoltaic power station with abundant solar energy resources around the cement plant is used to supply power to the water electrolysis cell 19, when green ammonia / green hydrogen replaces 20%~100% of the coal in the decomposition furnace, the air inlet of the tertiary air duct at the bottom of the decomposition furnace 6 is level with or slightly above the area. At this time, 50% of the oxygen produced by water electrolysis is supplied to the kiln head burner, and the remaining 50% of the oxygen replaces the cooling air of the grate cooler.

[0052] Cement raw materials with a moisture content of <0.5% and a particle size of 30-60μm are fed into the gas outlet pipe of the second cyclone separator 2. Under the influence of the airflow, they immediately disperse and suspend in the airflow, then enter the first cyclone separator 1, where they exchange heat with the hot gas. Using hydrogen as fuel reduces system pressure loss and heat loss carried away by the exhaust gas. When the overall moisture content of the raw material batch is high, the preheater outlet air temperature is maintained at 270-280℃. The dust-laden gas separated by the first cyclone separator 1 has its heat recovered by the waste heat power generation system 9, and then enters the dust collector 12 for further purification via a high-temperature fan 11. The dust concentration of the purified gas is ≤10mg / Nm³. 3 The water vapor in the flue gas is condensed by the water-vapor separator 13, and the recovered water is sent to the condensate tank 16. The water in the condensate tank 16 is then sent to the water electrolysis cell for recycling. The remaining tail gas is cooled by the condenser 14, and the carbon dioxide is liquefied at a medium pressure of 2.5 MPa and sent to the carbon dioxide storage tank 15.

[0053] After gas-material separation in the first cyclone 1, the powder material enters the gas outlet pipe of the third cyclone 3 through a flap valve and then enters the second cyclone 2 with the airflow, where it exchanges heat with the hot gas. After heat exchange, the material temperature is 320~420℃. After gas-material separation in the second cyclone 2, the powder material enters the gas outlet pipe of the fourth cyclone 4 through a flap valve and then enters the third cyclone 3 with the airflow, where it exchanges heat with the hot gas. After heat exchange, the material temperature is 430~530℃. After gas-material separation in the third cyclone 3, the powder material enters the gas outlet pipe of the fifth cyclone 5 through a flap valve and then enters the fourth cyclone 4 with the airflow. The raw powder material undergoes four stages of heat exchange—first cyclone 1, second cyclone 2, third cyclone 3, fourth cyclone 4, and the connecting pipes between the cyclones—and is thus fully preheated, with the material temperature after heat exchange being 530~620℃. The material is collected by the fourth cyclone separator 4 and enters the decomposition furnace 6 through a flap valve. The calcination temperature in the decomposition furnace 6 is 850~1000℃. The cement raw material after decomposition in the decomposition furnace 6 is carried by the airflow into the fifth cyclone separator 5 and then into the rotary kiln 7. After calcination into clinker, it is cooled by the grate cooler 8. After heat exchange, the material temperature is 70℃.

[0054] The flue gas exiting the preheater, after purification, enters the waste heat power generation system 9 to further utilize its heat. It then enters the raw material mill 10 to dry the raw materials. Using hydrogen as fuel, excessive moisture is generated in the flue gas, causing the dew point temperature to rise by about 20°C. Therefore, the waste heat power generation system at the kiln tail needs to be upgraded, and the inlet air temperature of the large bag filter at the kiln tail needs to be controlled above 90°C. After dust collection, the flue gas passes through a water-vapor separator, and the recovered water serves as 40%–70% of the water source for the electrolytic cell. Using green hydrogen and green ammonia as fuel in the clinker burning system reduces carbon dioxide emissions by 50% compared to using coal, which is of significant importance in reducing carbon emissions.

[0055] The low-carbon process for calcining cement clinker with green hydrogen-enriched oxygen, as described in this invention, achieves a system output of 5000 t / d. In this system, the concentrations of H2O and CO2 in the outlet gas of the first cyclone separator are higher than those in the traditional process. The outlet gas temperature and volume of the first exhaust gas subsystem are also lower than in the traditional process, controllable within 270±10℃. The system exhibits low heat consumption, a recovered CO2 concentration ≥60 vol.%, a CO2 capture rate ≥92 vol.%, and an SO2 concentration ≤10 mg / Nm³. 3 NO x Concentration ≤100mg / Nm 3 At the same time, it solves technical problems such as heat balance and environmental emissions, and achieves stable and long-term operation of the rotary kiln thermal system.

Claims

1. A system for calcining cement clinker using green hydrogen-green ammonia fuel, comprising a preheating subsystem, a calcination subsystem, and a cooling subsystem, characterized in that, It also includes a distributed photovoltaic power station subsystem, a water electrolysis subsystem, ammonia synthesis subsystem, and a water vapor separation subsystem; The power supply outlet of the distributed photovoltaic power station subsystem is connected to the power supply inlet of the water electrolysis subsystem; The water electrolysis subsystem includes a water electrolyzer (19), a hydrogen storage tank (20) connected to the hydrogen outlet of the water electrolyzer, an oxygen storage tank (21) connected to the oxygen outlet of the water electrolyzer, and a makeup water storage tank (18) connected to the water inlet of the water electrolyzer; the oxygen storage tank (21) is connected to the oxygen-enriched combustion aid inlet of the rotary kiln (7) and the cooling air inlet of the fixed bed in the grate cooler (8); the hydrogen storage tank (20) is connected to the hydrogen fuel inlet of the decomposition furnace (6) and the hydrogen inlet of the ammonia synthesis subsystem. The ammonia synthesis subsystem is also provided with a nitrogen inlet and an ammonia outlet, and the ammonia outlet is connected to the ammonia fuel inlet of the decomposition furnace (6). The flue gas inlet of the water vapor separation subsystem is connected to the flue gas outlet of the preheating subsystem, the liquid outlet is connected to the water inlet of the water electrolysis cell, and the flue gas outlet is connected to the inlet of the carbon dioxide storage tank.

2. The system for calcining cement clinker using green hydrogen-green ammonia fuel according to claim 1, characterized in that, The water vapor separation subsystem includes a water vapor separator (13) connected to the flue gas outlet of the preheating subsystem, a condenser (14) connected to the water vapor separator (13), a carbon dioxide storage tank (15) inlet connected to the gas outlet of the condenser (14), and a condensate tank (16) connected to the liquid outlet of the condenser (14); the condensate tank (16) is connected to the water inlet of the water electrolysis cell (19).

3. The system for calcining cement clinker using green hydrogen-green ammonia fuel according to claim 1, characterized in that, The ammonia synthesis subsystem includes an ammonia synthesis tower (22), the hydrogen inlet of which is connected to the hydrogen storage tank of the water electrolysis subsystem, the nitrogen inlet is connected to the nitrogen pipeline, and the ammonia outlet is connected to the ammonia fuel inlet of the decomposition furnace (6).

4. The system for calcining cement clinker using green hydrogen-green ammonia fuel according to claim 1, characterized in that, The calcination subsystem includes a decomposition furnace (6), a first burner (601) located at the bottom of the decomposition furnace (6), a second burner (602) and a third burner (603) located above the first burner (601), a rotary kiln (7), and a fourth burner (604) located at the kiln head of the rotary kiln (7); the gas outlet of the hydrogen storage tank (20) is connected to the gas inlet of the first burner (601) and the hydrogen inlet of the ammonia synthesis subsystem, respectively.

5. A method for calcining cement clinker using the system described in claim 1, characterized in that, Includes the following steps: (A) The distributed photovoltaic power station subsystem inputs electrical energy into the water electrolysis subsystem. After water is electrolyzed, green hydrogen and oxygen are produced. The green hydrogen and nitrogen separated from the air are then introduced into the ammonia synthesis subsystem to produce green ammonia. (B) Green hydrogen-green ammonia is introduced into the decomposition furnace (6) to replace part or all of the fuel coal in the decomposition furnace (6) and provide a heat source for the decomposition of raw materials; oxygen produced by electrolysis of water is used as an aid for oxygen-enriched combustion in the rotary kiln (7) and as cooling air for the fixed bed in the grate cooler (8). (C) The flue gas discharged from the raw material mill is purified and dust collected, and then separated into water vapor and CO2 by a water vapor separation system. The separated water vapor is condensed and returned to the electrolyzed water for recycling.

6. The method for calcining cement clinker according to claim 5, characterized in that, The green hydrogen / green ammonia is introduced into the lower part of the decomposition furnace (6) individually or simultaneously.

7. The method for calcining cement clinker according to claim 5, characterized in that, When the green hydrogen / green ammonia replaces 5% to 20% of the fuel coal in the decomposition furnace (6), the air is introduced between the upper part of the flue gas chamber constriction and the decomposition furnace (6); when the green hydrogen-green ammonia replaces 20% to 100% of the fuel coal in the decomposition furnace (6), the air is introduced into the tertiary air duct at the lower part of the decomposition furnace (6) at the same level or close to the upper area.

8. The method for calcining cement clinker according to claim 5, characterized in that, When the green hydrogen / green ammonia replaces the fuel coal in the decomposition furnace, hydrogen is set up with a separate burner, and ammonia is set up with a separate burner or blended into the fuel coal.

9. The method for calcining cement clinker according to claim 5, characterized in that, Ammonia is co-fired into the fuel coal. Ammonia enters the decomposition furnace (6) through the central airflow. Pulverized coal enters the decomposition furnace (6) through the annular nozzle. Air enters the decomposition furnace (6) through the swirl blades to form a rotating airflow.

10. The method for calcining cement clinker according to claim 5, characterized in that, 5% to 50% of the oxygen produced by electrolysis of water is used as an aid for oxygen-enriched combustion in the rotary kiln (7), and the remainder is used as cooling air for the grate cooler (8), which is introduced from the cooling air inlet of the fixed bed of the grate cooler (8).

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