System and method for producing low-carbon cement by utilizing photovoltaic power generation hydrogen production

Abstract

The invention discloses a system and method for producing low-carbon cement through photovoltaic power generation hydrogen production. The system comprises a photovoltaic power generation system, a water electrolysis hydrogen production system, a raw material grinding system, a rotary kiln calcination system, a cement grinding system and a carbon resource utilization device. The photovoltaic system provides a clean power supply for the electrolysis device, and a solid oxide electrolytic tank is adopted to efficiently prepare hydrogen at high temperature; hydrogen is input into the rotary kiln through a multi-point injection and oxygen combustion-supporting structure to serve as unique fuel, and zero carbon emission in the cement calcination process is achieved; carbon dioxide in tail gas of the system is purified and then synthesized into methanol together with hydrogen, and an energy-carbon cycle closed-loop path is constructed; linkage optimization of photovoltaic output, electrolytic load, calcination heat intensity and carbon conversion efficiency is realized through a multi-stage waste heat recovery and intelligent control system; the method has the remarkable advantages in the aspects of improving the energy utilization efficiency, reducing carbon emission and promoting resource collaboration and intelligent control, and is suitable for construction of a novel green cement industrial platform.

Description

Technical Field

[0001] The present invention relates to the technical field of low-carbon cement production, and specifically to a system and method for producing low-carbon cement by using hydrogen production from photovoltaic power generation. Background Art

[0002] According to the current domestic cement production status, cement production is one of the main sources of global carbon emissions, accounting for about 8% of global anthropogenic carbon dioxide emissions, and its carbon emissions are quite huge; the traditional cement production process is "three grinding and one burning", that is, grinding raw materials, grinding coal powder, burning clinker, and grinding cement. The rotary kiln uses the heat generated by burning fossil fuels (such as coal and natural gas) to burn the ground raw materials to prepare clinker. The prepared clinker is proportioned with materials such as fly ash and gypsum, and then ground to finally form cement; the large use of coal powder as the calcination fuel not only has high carbon emissions, but also is difficult to achieve dynamic energy consumption control, restricting the development of green manufacturing. The industry has carried out various technical explorations, including directions such as hydrogen energy replacing coal, photovoltaic power supply, carbon capture and resource utilization.

[0003] Patent publication number CN117069401A discloses a zero-carbon cement production device and production method based on hydrogen energy utilization. Its technical solution includes: using a hydrogen production system to generate hydrogen to replace part of the coal powder fuel supplied to the rotary kiln system, and recovering carbon dioxide by-product gas through a methanol synthesis system; the advantages of this solution are: on the premise of not significantly transforming the existing cement production line, the use of coal is reduced, and partial carbon emissions reduction is achieved. However, its hydrogen is only an auxiliary fuel with a proportion of 5%-30%, and it still cannot get rid of the dependence on coal powder, and the carbon emissions reduction range is limited; moreover, the hydrogen raw material used in this system is obtained by methanol reforming, and there is still an indirect emission problem of fossil energy. Patent publication number CN218915948U discloses a system for achieving zero-carbon emissions in a cement plant by using renewable green hydrogen. This system uses photovoltaic or wind energy as the energy source, produces hydrogen and oxygen by electrolyzing water, supplies hydrogen to the cement rotary kiln for combustion, and at the same time captures carbon dioxide in the tail gas and synthesizes methanol with hydrogen to achieve carbon resource utilization. However, this solution does not deeply optimize the energy scheduling strategy between each subsystem. For example, there is a lack of a coordination mechanism between photovoltaic output, electrolysis load, and hydrogen heating load, and it is difficult to adapt to the energy efficiency stability problem caused by the fluctuation of renewable energy, resulting in the need to improve the system operation efficiency.

[0004] Patent Publication No. CN115961294A discloses a carbon-based chemical product preparation system and method with zero carbon emissions. Hydrogen is generated by an electrolyzed water hydrogen production system driven by renewable energy power generation. Then, carbon dioxide in the carbon-containing flue gas is captured and reacted with hydrogen or water under electrocatalytic / thermal catalytic conditions to synthesize carbon-based chemical products such as methanol and ethanol. This existing technology is mainly applied to the general platform structure of carbon-emitting industries such as chemical industry, electric power, and iron and steel. Its system construction is not customized for the production chain characteristics of the cement industry and has the following technical limitations: It is not applicable to the key links in the cement production process, such as raw material grinding, rotary kiln calcination, cement grinding, etc., which are not included in the overall energy scheduling and carbon resource recovery mechanism. Similarly, Patent Publication Nos. CN117563407A, CN116478014A, and CN117175679A also have the above problems. In summary, although existing technologies have attempted to introduce hydrogen energy and renewable energy into the cement production field to achieve a certain degree of carbon emission reduction or carbon cycle, the following technical problems have not been effectively solved: Traditional hydrogen substitution for coal combustion technology still adopts a partial substitution scheme and cannot achieve zero carbonization of the fuel in the rotary kiln; renewable energy systems such as photovoltaics have large fluctuations; the carbon dioxide resource utilization path is single, and a multi-functional energy closed-loop system coupled with hydrogen energy has not been formed; the utilization efficiency of waste heat and surplus energy is not high, and the cascade utilization of energy and the energy closed-loop at the production line level have not been fully realized.

[0005] Therefore, there is an urgent need for an integrated technical solution that integrates photovoltaic hydrogen production, intelligent joint regulation, full hydrogen substitution combustion, carbon dioxide resource recycling, and multi-stage energy recovery, which can not only achieve zero carbon emissions in the entire process of the rotary kiln but also have excellent energy efficiency regulation capabilities to adapt to the trend of green cement manufacturing dominated by new energy. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the existing defects and provide a low-carbon cement production system and method using photovoltaic power generation to produce hydrogen. By constructing a comprehensive system that integrates photovoltaic power generation, high-efficiency SOEC electrolysis, hydrogen partition combustion, carbon dioxide methanol synthesis, and intelligent control, a complete "energy-carbon linkage closed-loop" is formed. This system not only realizes the zero pulverized coal and zero carbon emission fuel substitution in the rotary kiln calcination process but also drives the electrolytic cell through tail gas waste heat to produce high-purity hydrogen and oxygen, significantly improving the energy utilization efficiency and effectively solving the problems in the background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: A system and method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen, including a system for producing low-carbon cement by using photovoltaic power generation to produce hydrogen. The system is composed of a photovoltaic power generation system, an electrolytic water hydrogen production system, a raw material grinding system, a rotary kiln calcination system, and a cement grinding system. The photovoltaic power generation system includes photovoltaic panels, an inverter, and a storage battery. The photovoltaic panels are installed on the rain shelter of the cement system. The rain shelter mainly provides rain protection for the equipment or key components on the cement production line. It is replaced with photovoltaic panels to convert solar energy into electrical energy and realize the utilization of clean energy. The electrical energy collected by the photovoltaic panels is converted by the inverter and stored in the storage battery. The electrolytic water hydrogen production system includes an electrolytic cell, a hydrogen gas storage tank, and an oxygen gas storage tank. The electrolytic cell is connected to the hydrogen gas storage tank and the oxygen gas storage tank respectively. The water in the electrolytic cell is electrolyzed by the electricity in the storage battery to produce hydrogen and oxygen, which are stored in the hydrogen gas storage tank and the oxygen gas storage tank respectively. The raw material grinding system includes a raw material bin 1, a raw material vertical mill, a dust collector 1, a raw material finished product bin, and a chimney 1. The discharge port of the raw material bin 1 is connected to the feed port of the raw material vertical mill. The discharge port of the raw material vertical mill is connected to the dust collector 1. The discharge port of the dust collector 1 is connected to the raw material finished product bin. The dust outlet of the dust collector 1 is connected to the chimney 1. The main function of the raw material vertical mill is to grind the raw material with a particle size ≤50mm into a powdery material of about 80μm. The rotary kiln calcination system includes a cyclone preheater, a rotary kiln, a grate cooler, a dust collector 2, a chimney 2, and a clinker finished product bin. The raw material finished product bin is connected to the feed port of the rotary kiln through the cyclone preheater. The fuel inlet of the rotary kiln is connected to the hydrogen gas storage tank. The discharge port of the rotary kiln is connected to the feed port of the grate cooler. The cyclone preheater is connected to the chimney 2 through the dust collector 2. The discharge port of the grate cooler and the discharge port of the dust collector 2 are connected to the clinker finished product bin. The main function of the rotary kiln calcination system is to form clinker by heating, calcining, and cooling the powdery raw material finished product of 80μm after grinding, which can be used as one of the cement raw materials. The cement grinding system includes a raw material bin 2, a cement vertical mill, a dust collector 3, and a finished product bin. The feed port of the raw material bin 2 is connected to the cement batching system. The discharge port of the raw material bin 2 is connected to the feed port of the cement vertical mill. The cement vertical mill is connected to the finished product bin through the dust collector 3. The main function of the cement grinding system is to mix the clinker with materials such as fly ash and gypsum, and grind them into a finished product with a specific surface area of 3300-3800 cm² / g by a vertical mill, which is the cement. The method includes the following steps: Step 1: Use the photovoltaic panels installed on the rain shelter of the cement production line to collect solar energy and convert it into direct current electricity through an inverter. The direct current electricity is used for the electrolytic water hydrogen production system; Step 2: The electrolytic water hydrogen production system electrolyzes water to generate hydrogen and oxygen. The hydrogen is stored in the hydrogen gas storage tank for standby, and the oxygen in the oxygen gas storage tank is used for subsequent combustion support or sale; Step 3: Feed the hydrogen gas as the sole fuel into the rotary kiln instead of pulverized coal, and conduct efficient combustion through a multi-point injection combustion structure to realize the process of calcining raw meal into clinker; Step 4: In Step 2, convey the remaining hydrogen gas generated and the carbon dioxide generated in the rotary kiln calcination system to the methanol synthesis system for reaction to produce green methanol for sale or in-plant use; Step 5: Mix the clinker obtained from the rotary kiln calcination system with fly ash and gypsum auxiliary materials in proportion, and send them into the cement grinding system for grinding to the target specific surface area to obtain the cement finished product; Step 6: Conduct hierarchical heat exchange on the waste heat of the rotary kiln calcination system and the electrolyzed water system through a multi-stage waste heat recovery system, and respectively use it for electrolytic cell heating, plant heating or energy supply for other low-temperature process sections; Step 7: Adopt an intelligent control system to dynamically and jointly adjust the photovoltaic power generation, electrolysis load, hydrogen gas flow rate, calcination temperature and methanol synthesis efficiency in Steps 1 to 6 to achieve the optimization of the thermal-electric-carbon linkage balance.

[0008] Furthermore, the feed inlet of Raw Material Bin 1 is connected with a batching system. The batching system includes a limestone bin, an iron ore tailings bin and a clay bin. The discharge outlets of the limestone bin, the iron ore tailings bin and the clay bin are respectively connected with the feed inlet of Raw Material Bin 1 through conveyors.

[0009] Furthermore, the electrolytic cell is a solid oxide electrolytic cell. The working temperature of the solid oxide electrolytic cell is 600°C - 850°C. Yttria-stabilized zirconia is used as the solid electrolyte, Ni-YSZ is used as the cathode, and La 1-x Sr x MnO 3 is used as the anode. At high temperature, water vapor is electrolyzed to generate hydrogen gas and oxygen gas; the exhaust temperature of the rotary kiln tail gas is generally 300 - 450°C, and it can reach 600 - 850°C after heat exchange; the stable working range of the solid oxide electrolytic cell is exactly 600 - 850°C, which is naturally matched with the system heat source and does not require additional energy consumption for heating. The high-temperature heating of the electrolytic cell is through heat exchange with the waste heat of the rotary kiln calcination system tail gas to provide working heat energy for the electrolyzed water hydrogen production system. This solid oxide electrolytic cell uses reaction heat to assist in decomposing water, has the lowest power consumption, and produces high-purity hydrogen gas and oxygen gas. The electrolysis efficiency is significantly higher than that of the normal-temperature electrolysis method, is suitable for the waste heat temperature range of the rotary kiln tail gas, and this material system has a mature process, fast response, and can adapt to intermittent power input, and has good industrial adaptability and popularization.

[0010] Further, the hydrogen storage tank is sent into the methanol synthesis system after being treated by a gas dryer. The carbon dioxide discharged from the rotary kiln tail gas is treated and then sent into the methanol synthesis system together with the hydrogen treated by the gas dryer in the hydrogen storage tank. The methanol synthesis system includes a mixing and compression unit, a catalytic reaction unit, a condensation and separation unit, and a recycling unit. The mixing and compression unit is used to mix hydrogen and carbon dioxide at a molar ratio of 3:1 and compress it to 5-10 MPa; the catalytic reaction unit is a fixed bed reactor filled with a Cu / ZnO / Al 2 O 3 heterogeneous catalyst, and a catalytic synthesis reaction is carried out under the conditions of 250°C and 7 MPa; the condensation and separation unit is used to cool the reaction products to below 30°C to precipitate methanol liquid and separate it from the unreacted gas; the recycling unit is used to send the unreacted gas back to the mixing and compression unit for cyclic reaction.

[0011] Further, the carbon dioxide passes through a particle filter to remove dust particles, and then passes through an alkali liquor scrubbing tower to remove NO x 、SO 2 acid gases; finally, it passes through a drying tower to remove water vapor; after purification, carbon dioxide gas with a concentration of more than 80% is obtained.

[0012] Further, the mixing and compression unit is equipped with an automatic proportional regulating valve and a pressure control feedback system for dynamically adjusting the flow ratio of hydrogen and carbon dioxide to match the reaction load.

[0013] Further, the condensation and separation unit includes a cooling heat exchanger and a methanol collection tank, and the unreacted gas is cooled and then separated by a gas-liquid separator and discharged into the circulation loop.

[0014] Further, the electrolytic water hydrogen production system is connected to multiple hydrogen injection nozzles, and the injection nozzles are longitudinally distributed along the rotary kiln; the electrolytic water hydrogen production system has multiple oxygen injection nozzles to provide auxiliary oxygen to the periphery of the hydrogen injection nozzles or the central cavity of the rotary kiln; the control unit is used to monitor the temperature distribution of each section of the rotary kiln in real time and adjust the hydrogen injection flow rate and oxygen supply ratio of each nozzle group to achieve controllable temperature zoning and optimized combustion efficiency; this system is applicable to the low-carbon calcination scenario using hydrogen as the sole fuel for the rotary kiln, effectively avoiding the risks of local overheating and deflagration.

[0015] The control unit includes a temperature acquisition module, a PID control module, and a flow control module. The control logic includes feedback adjustment of the hydrogen / oxygen ratio and opening sequence according to different temperature zones. This intelligent control system is used to achieve energy-carbon resource coordinated regulation and operation optimization under the fluctuations of photovoltaic power output, electrolytic load, rotary kiln heat supply, carbon dioxide production, etc.

[0016] By setting multiple hydrogen injection ports on the rotary kiln shell and introducing auxiliary oxygen, multi-region independent heating and efficient mixed combustion are achieved, significantly optimizing the temperature distribution, enhancing the uniformity and stability of the calcination process, and effectively avoiding the risks of local overheating and deflagration caused by traditional centralized injection. At the same time, the oxygen-assisted method improves the combustion efficiency and flame coverage of hydrogen, ensuring an efficient, controllable, and zero-carbon emission calcination process without relying on fossil fuels, and having good system safety and low-carbon collaborative application value.

[0017] Furthermore, the feed inlet of the second raw material silo is connected to a cement batching system, which includes a clinker finished product silo, a fly ash silo, and a gypsum silo. The discharge outlets of the clinker finished product silo, the fly ash silo, and the gypsum silo are respectively connected to the feed inlet of the second raw material silo.

[0018] Furthermore, the hot air inlets of the vertical raw material mill and the vertical cement mill are respectively connected to the high-temperature tail gas generated by the rotary kiln calcination system through hot air pipelines; the waste heat is introduced into the vertical mill system through waste heat conduits as its hot air source to promote the drying and transportation of raw meal and cement powder. This hot air recovery path not only reduces the overall energy consumption but also enhances the energy closed-loop coupling effect of the system, further improving energy efficiency.

[0019] Compared with the prior art, the beneficial effects of the present invention are: Using this technology, "two grinding and one burning", that is, grinding raw meal, burning clinker, and grinding cement, can be achieved, and the coal powder grinding link can be cancelled; through photovoltaic power generation to produce green electricity and using electrolyzed water to generate hydrogen, the fuel of the rotary kiln equipment is changed from coal powder to hydrogen energy, and zero carbon emissions of fuel combustion in this link can be directly achieved; at the same time, due to the cancellation of the coal powder grinding link, carbon emissions in this link can be directly eliminated, thus achieving the goal of low-carbon cement production.

[0020] 2. By constructing an energy system based on photovoltaic power generation and centered on high-temperature electrolyzed water hydrogen production, for the first time, the entire process of rotary kiln calcination is completely replaced with hydrogen as the sole heat source, getting rid of the dependence on fossil fuels in the traditional cement production process; in the traditional process, coal powder calcination not only has a high carbon emission intensity but also has problems such as inflexible combustion regulation and local overheating. In contrast, the present invention uses high-purity hydrogen as fuel and achieves uniform combustion with the assistance of multi-point nozzles and oxygen, significantly reducing the risks of carbon emissions and heat loss; canceling the coal grinding link can further reduce carbon emissions, equipment maintenance, and dust pollution, promoting the development of the cement industry towards the direction of zero-carbon fuel substitution from the system structure.

[0021] 3. The core technical path lies in achieving the full-chain energy synergy and carbon resource coupling closed-loop from solar energy collection to hydrogen production, rotary kiln combustion, carbon dioxide recovery, methanol synthesis, and waste heat reuse of tail gas. Among them, the heat source of the SOEC high-temperature electrolysis module directly comes from the rotary kiln tail gas, and through heat exchange, a hydrogen production method without additional heating is realized. The vertical mill system also uses the tail gas as the hot air source, improving the energy closed-loop level. After carbon dioxide capture, it is further used for methanol synthesis, which not only reduces greenhouse gas emissions but also produces high-value products, realizing the conversion and utilization of carbon resources. The entire system constitutes a complete cycle from energy input to heat-carbon conversion and then to material output, significantly improving the comprehensive energy utilization efficiency and environmental friendliness.

[0022] 4. In the calcination process, the present invention proposes a collaborative heating scheme of multi-point hydrogen injection and annular oxygen assistance, combined with an intelligent temperature control module, to achieve independent regulation and dynamic adjustment of each temperature zone of the rotary kiln. Compared with the traditional centralized combustion method, this structure significantly reduces the risks of local overheating and flame instability, improving the combustion uniformity and system safety. Brief Description of the Drawings

[0023] Figure 1 is a schematic diagram of the system of the present invention; Figure 2 is a schematic diagram of the methanol synthesis system of the present invention.

[0024] In the figure: 1 limestone silo, 2 iron ore tailings silo, 3 clay silo, 4 raw material silo 1, 5 raw meal vertical mill, 6 dust collector 1, 7 raw meal finished product silo, 8 cyclone preheater, 9 chimney 1, 10 inverter, 11 photovoltaic panel, 12 rotary kiln, 13 electrolytic cell, 14 hydrogen gas storage tank, 15 oxygen gas storage tank, 16 grate cooler, 17 dust collector 2, 18 chimney 2, 19 clinker finished product silo, 20 fly ash silo, 21 gypsum silo, 22 raw material silo 2, 23 cement vertical mill, 24 dust collector 3, 25 finished product silo. Detailed Embodiments

[0025] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. Embodiment 1

[0026] Please refer to Figure 1-2, the present invention provides a technical solution: a system and method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen, including a system for producing low-carbon cement by using photovoltaic power generation to produce hydrogen. The system consists of a photovoltaic power generation system, a water electrolysis hydrogen production system, a raw material grinding system, a rotary kiln calcination system, and a cement grinding system. The photovoltaic power generation system consists of a photovoltaic panel 11, an inverter 10, and a storage battery installed on the rain shelter of the cement system. After collecting solar energy, the photovoltaic panel 11 converts the electric energy through the inverter 10 and stores it in the storage battery; the water electrolysis hydrogen production system consists of an electrolysis water tank 13, a hydrogen gas storage tank 14, and an oxygen gas storage tank 15. After the electrolysis water tank 13 is powered on, water is decomposed into hydrogen and oxygen, which are respectively stored in the hydrogen gas storage tank 14 and the oxygen gas storage tank 15; the raw material grinding system includes a raw material bin 1 4, a raw material vertical mill 5, a dust collector 1 6, a raw material finished product bin 7, and a chimney 1 9. The raw materials are ground by the raw material vertical mill 5 from the raw material bin 1 4 and then processed by the dust collector 1 6, and finally stored in the raw material finished product bin 7, and the dust is discharged through the chimney 1 9; the rotary kiln calcination system consists of a cyclone preheater 8, a rotary kiln 12, a grate cooler 16, a dust collector 2 17, a chimney 2 18, and a clinker finished product bin 19. The raw material is preheated by the cyclone preheater 8 and then enters the rotary kiln 12 for calcination. The required fuel is hydrogen, which is supplied by the hydrogen gas storage tank 14. The produced clinker is cooled by the grate cooler 16 and then enters the clinker finished product bin 19; the flue gas is discharged from the chimney 2 18 after being processed by the dust collector 2 17; the cement grinding system consists of a raw material bin 2 22, a cement vertical mill 23, a dust collector 3 24, and a finished product bin 25. The clinker is mixed with fly ash, gypsum, etc. and ground to obtain a cement finished product with a specific surface area of 3300-3800 cm² / g; the method includes seven steps, which are: solar energy collection and power supply, water electrolysis hydrogen production, hydrogen fuel calcination, hydrogen and carbon dioxide to produce methanol, finished cement production, waste heat multi-stage recovery, and intelligent control joint adjustment.

[0027] In this embodiment, by replacing the traditional rain shelter material with the photovoltaic panel 11, it converts solar energy into electric energy, stores it through the inverter 10 and the storage battery, and supplies power to the electrolysis water tank 13 for the water electrolysis reaction to produce high-purity hydrogen and oxygen; hydrogen is used as the only fuel for the rotary kiln 12 and enters the calcination zone through a multi-point injection combustion system to achieve efficient and uniform combustion. The raw material is converted into clinker through the high-temperature reaction of the rotary kiln 12, cooled by the grate cooler 16 and stored in the clinker finished product bin 19; the by-product oxygen is used for combustion support or sold externally; the waste heat is used for electrolytic cell heating and plant energy supply through heat exchange to improve energy efficiency; at the same time, the hydrogen-rich gas generated by electrolysis and the carbon dioxide in the calcination tail gas are jointly sent to the methanol synthesis device to produce green methanol, forming an energy-carbon coupling closed loop; in addition, the intelligent control system monitors the parameters of each process node in real time, dynamically adjusts the photovoltaic power output, electrolysis load, hydrogen flow rate, and combustion temperature, and realizes the linkage of heat-electricity-carbon balance.

[0028] Compared with the traditional cement production method, this system eliminates the coal powder preparation and combustion links, achieving complete decarbonization in the calcination process; uses high-temperature electrolysis technology to improve the electrolysis efficiency, and effectively utilizes the waste heat of the rotary kiln tail gas as the electrolysis heat source, significantly reducing energy consumption; the intelligent control system ensures the coordinated operation of each link, improving the energy conversion efficiency and the recycling rate of carbon resources; the system can achieve clean energy drive and low-carbon emissions throughout the cement production process, promoting the industry's development towards green manufacturing.

[0029] In the above solution, the photovoltaic panels 11 can also be installed on the rooftops of other buildings in the factory area to further expand the area of clean energy utilization; the electrolysis water tank 13 can be replaced with an alkaline electrolysis cell or a proton exchange membrane system. Although the power consumption is relatively high, the equipment structure is simpler and is suitable for small and medium-sized scenarios.

[0030] In a possible implementation manner, the feed inlet of the first raw material bin 4 is connected with a batching system. The batching system includes a limestone bin 1, an iron ore tailings bin 2, and a clay bin 3. The discharge outlets of the limestone bin 1, the iron ore tailings bin 2, and the clay bin 3 are respectively connected to the feed inlet of the first raw material bin 4 through conveyors.

[0031] This implementation manner adds a dedicated batching system at the front end of the raw meal grinding system for pre-mixing and conveying the main raw materials required for cement production, namely limestone, iron ore tailings, and clay; the limestone bin 1, the iron ore tailings bin 2, and the clay bin 3 serve as raw material storage units, and an automatic discharging device is arranged below them. Different proportions of raw materials are respectively conveyed into the first raw material bin 4 through conveyors to complete unified feeding, and then sent to the raw meal vertical mill 5 for grinding treatment; this batching system can achieve continuous and stable material supply, and ensure that the proportions of various raw materials meet the preset process requirements by controlling the discharging rate and sequence.

[0032] By setting up a dedicated batching system, this implementation manner significantly improves the accuracy and automation level of raw material supply, effectively avoiding the proportion error and stability problems caused by manual batching; at the same time, using conveyors for automatic feeding can reduce material loss and dust pollution, improving the overall operation efficiency; especially using iron ore tailings as raw materials not only realizes the resource utilization of solid waste, but also reduces the raw material cost and improves the environmental friendliness and resource utilization rate of the system; in addition, this batching system is highly matched with the downstream vertical mill system, ensuring the continuous and stable operation of the subsequent grinding process and helping to improve the overall operation efficiency of the cement production line.

[0033] In the above solution, the discharging structures of the limestone silo 1, the iron ore tailings silo 2, and the clay silo 3 can adopt various methods such as vibrating feeders, screw conveyors, or gravity chute pipes to adapt to the physical properties and process requirements of different raw materials; in terms of conveying equipment, belt conveyors, pneumatic conveying, or chain plate conveying devices can also be used according to the layout of the production line to enhance the flexible deployment ability; in some areas with limited resources, the iron ore tailings can also be replaced with other rich iron slag or high-iron ore powder to achieve a functionally equivalent raw material substitution; to improve the batching accuracy, the system can also integrate weighing sensors and proportional control systems, and set the flow ratio of different materials through the PLC program to achieve a more accurate intelligent batching control.

[0034] In a possible implementation, the electrolysis water tank 13 is a solid oxide electrolyzer. The operating temperature of the solid oxide electrolyzer is 600°C - 850°C. Yttria-stabilized zirconia is used as the solid electrolyte, Ni-YSZ is used as the cathode, and La 1 - X Sr x MnO 3 is used as the anode. Under high-temperature conditions, water vapor is electrolyzed to generate hydrogen and oxygen; the exhaust temperature of the rotary kiln is generally 300°C - 450°C, and it can reach 600°C - 850°C after heat exchange. Its temperature range matches that of the electrolyzer. The high-temperature heat supply of the electrolysis water tank 13 is achieved by heat exchange with the waste heat of the rotary kiln calcination system tail gas, providing working heat energy for the electrolytic water hydrogen production system.

[0035] In this implementation, a solid oxide electrolyzer (SOEC) is used as the core device for electrolytic water hydrogen production. This electrolyzer utilizes the reaction that occurs at the interface between water vapor and the solid electrolyte at high temperature to generate hydrogen and oxygen; the core material system of SOEC includes a Ni-YSZ composite cathode, a YSZ ceramic electrolyte layer, and La 1 - X Sr x MnO 3 anode, which can operate stably in the range of 600°C - 850°C; since the exhaust gas temperature of the rotary kiln 12 is 300°C - 450°C and can reach the temperature range required by SOEC after being heated by an efficient heat exchange structure, there is no need for additional heating energy to maintain the temperature of the electrolyzer; the system introduces the waste heat energy of the rotary kiln tail gas into the electrolyzer through a heat exchanger to achieve the recovery and utilization of heat energy, and at the same time drives the high-temperature electrolysis reaction of water vapor, outputs high-purity hydrogen for cement calcination, and the by-product oxygen can be used for combustion support or sold externally in industry.

[0036] The SOEC module includes: the electrolyzer main body, which is composed of a multi-layer series structure, and each electrolysis unit adopts the following material configuration: Cathode: Made of Ni-YSZ composite material, with the mass fraction of YSZ (yttria-stabilized zirconia) being 50%, the particle size of nickel powder being 1 - 3 μm, and the composite structure electrode layer is obtained by co-firing. It has good electron-oxygen ion dual conductivity and porous structure, which is beneficial for the reaction of water vapor on the electrode surface to generate hydrogen; Electrolyte layer: Made of YSZ (yttria-stabilized zirconia) ceramic sheet, with a thickness of 50 - 100 μm, having high oxygen ion mobility and stable working performance in the temperature range of 600 - 850 °C; Anode: Using La 0.8 Sr 0.2 MnO 3 as the main material, preparing perovskite-type conductive ceramics, coating on the other side of the electrolyte and forming a dense layer through high-temperature sintering, which is used for oxygen ions to release electrons to form oxygen; Heating and thermal coupling structure: The electrolytic cell module is equipped with an independent heat preservation shell, which exchanges heat with the flue gas at the tail end of the cement rotary kiln through the heat exchanger coil at the lower part of the shell. After heat exchange, the internal temperature of the SOEC is maintained in the range of 720 °C - 780 °C, and no external electric heating is required; Photovoltaic power supply system interface: In this embodiment, the SOEC module is connected to the output end of the photovoltaic inverter through the DC bus, adopting a dynamic voltage stabilization control strategy. When the photovoltaic sunlight is strong and the power generation is high, it conducts maximum power point tracking (MPPT) power supply to drive the SOEC system to carry out efficient water vapor electrolysis; Steam input and gas production output path: The water source is the recycled water in the factory, which is heated to 250 °C through a multi-stage evaporation heating system and then input into the SOEC module; The hydrogen product is directly introduced into the hydrogen storage tank 14 and used for the rotary kiln calcination fuel system; The by-product oxygen enters the oxygen storage tank 15 after dehydration and can be used for the rotary kiln combustion support system or sold externally.

[0037] Operating continuously for 48 hours under the above structure, the average hydrogen production rate of the SOEC module is 0.36 Nm³ / h, the average hydrogen production per kilowatt of photovoltaic electric energy is 0.03 Nm³, the hydrogen production efficiency reaches 82%, which is about 30% higher than that of normal temperature electrolysis, and the system stability is good.

[0038] Compared with the traditional alkaline electrolytic cell (AEC) or proton exchange membrane electrolysis system (PEM), the solid oxide electrolytic cell (SOEC) system adopted in the present invention has higher thermal energy adaptability and energy conversion efficiency; its high-temperature operation characteristics enable it to make full use of the waste heat of the tail gas generated in the cement production process, reduce the overall energy consumption of the system, and at the same time achieve high-purity hydrogen output, which is more suitable for industrial-grade hydrogen calcination requirements, and has the advantages of high long-term operation stability, low equipment corrosion risk, and low operation and maintenance cost.

[0039] In practical applications, the SOEC module can adopt a single-cell series or multi-group parallel structure, and can be flexibly configured according to the hydrogen production scale. If the waste gas heat on-site is insufficient, it can also be supplemented with electric heating or a high-temperature heat storage system to stabilize the operating temperature of the SOEC. The electrolyte material can be replaced with other ceramic materials with high oxygen ion conductivity, such as GDC (gadolinium-doped ceria) or LSGM (lanthanum strontium molybdate oxide doped with strontium) to improve the conductivity. In terms of the power supply interface, the SOEC can also be connected to other renewable energy power sources such as wind energy and geothermal energy to achieve multi-energy coupled input. At the same time, the system can also be extended to a modular structure, which is convenient for distributed deployment or integration with cement production lines of different capacities, improving the system adaptability and flexible deployment ability.

[0040] In a possible implementation manner, the hydrogen storage tank 14 is sent to the methanol synthesis system after being processed by the gas dryer, and the carbon dioxide discharged from the tail gas of the rotary kiln 12 is processed and then sent to the methanol synthesis system together with the hydrogen processed by the gas dryer. The methanol synthesis system includes a mixing and compression unit, a catalytic reaction unit, a condensation and separation unit, and a recycling unit. The mixing and compression unit is used to mix hydrogen and carbon dioxide at a molar ratio of 3:1 and compress it to 5-10 MPa. The catalytic reaction unit is a fixed-bed reactor filled with Cu / ZnO / Al 2 O 3 multiphase catalyst, and a catalytic synthesis reaction is carried out under the conditions of 250°C and 7 MPa. The condensation and separation unit cools the product to below 30°C to precipitate methanol. The recycling unit is used to send the unreacted gas back to the mixing and compression unit for recycling.

[0041] In this embodiment, hydrogen is sourced from a solid oxide electrolysis cell (SOEC), and carbon dioxide is sourced from the tail gas of the rotary kiln calcination. The two are catalytically reacted to synthesize methanol, realizing an integrated path of "carbon capture-conversion-utilization".

[0042] I. Raw material gas acquisition and pretreatment: Hydrogen source: High-purity hydrogen is continuously produced by the SOEC system, with a hydrogen purity greater than 99.99%. After being processed by the gas dryer, it is sent to the methanol synthesis system. Carbon dioxide source: A branch is set on the tail gas exhaust pipeline of the rotary kiln 12 and pretreated through the following devices: Particle filter: Remove dust particles; Alkali scrubbing tower: Remove NO x 、SO 2 and other acidic gases; Drying tower: Remove water vapor; Carbon dioxide gas with a concentration of more than 80% is obtained after purification.

[0043] II. Mixing and pressurization: Hydrogen and carbon dioxide gases are mixed at a molar ratio of 3:1 and enter a three-stage compression system through a gas mixing device. After being pressurized to 7.0 MPa and preheated to 180 °C, they enter the reactor.

[0044] III. Catalytic reaction section: The mixed gas is introduced into a fixed-bed catalytic reactor filled with Cu / ZnO / Al 2 O 3 catalyst (particle size 2 - 3 mm, bulk density 0.8 g / cm³). The reaction conditions are set as follows: Reaction temperature: 250 °C; reaction pressure: 7.0 MPa; residence time: about 1.5 seconds; Under these conditions, the conversion rates of hydrogen and carbon dioxide are stable. The methanol production rate is 0.45 kg / h, and the by-product water vapor enters the condensation section along with the gas stream.

[0045] IV. Product cooling and separation: The reaction tail gas is cooled to 25 °C by a shell-and-tube cooler and enters a gas-liquid separator and then a collection tank. The liquid component is methanol with a purity ≥ 98% and trace amounts of water. After distillation, pure methanol products are collected; the main components of the unreacted gas are hydrogen, carbon dioxide, and trace amounts of carbon monoxide, which are compressed and returned to the gas mixing section for recycling.

[0046] V. Intelligent control and energy coordination: The system is equipped with a temperature-pressure dual-feedback control system to adjust the feed ratio, reaction temperature, and recycle flow rate. At the same time, it conducts data docking with the photovoltaic power generation, electrolytic hydrogen production, and rotary kiln temperature control modules of the main system to achieve multi-source joint regulation.

[0047] VI. Implementation effects: The system operates continuously for 72 hours. The methanol yield of the system is 38%, and the hydrogen utilization rate is about 85%. It realizes partial sequestration and utilization of carbon dioxide in the cement production process and converts green hydrogen into high-value-added chemicals, with good energy efficiency and economic potential; In this embodiment, the hydrogen heating system is used to replace the traditional coal powder or natural gas heating method to build a clean, safe, and low-carbon calcination heat source path.

[0048] I. Structural configuration of the hydrogen injection and oxygen assistance device: Rotary kiln body: The used rotary kiln has a diameter of 3.5 m and a length of 58 m, and the inner lining of the cylinder is refractory material; Nozzle arrangement method: 9 groups of hydrogen injection - oxygen assistance nozzle groups are arranged along the length direction of the kiln body, with a spacing of 6 m; Each group of nozzles includes 1 central hydrogen nozzle and 3 - 4 annular oxygen nozzles, forming a coaxial circulating flow structure; The nozzle is made of 625 alloy material, with a temperature resistance of up to 1100 °C, and is equipped with a water-cooled sleeve. Injection angle and layout: The inclination angle of the central hydrogen injection port is 20° - 30°, facing the material propulsion direction. The annular oxygen injection ports are arranged around the main nozzle to form a locally oxygen-rich mixing zone.

[0049] II. Parameter settings of the gas supply system: Hydrogen source: Continuously supplied by the SOEC system, with a pressure of 0.8 MPa and a purity greater than 99.99%, and supplied to each nozzle through a branched pressure-stabilizing pipeline. Oxygen source: Part is the by-product oxygen of the SOEC, and part is supplied by the low-pressure liquid oxygen system. The oxygen injection pressure is 0.5 MPa. Mixing ratio and injection speed: The designed hydrogen / oxygen volume ratio for each group of nozzles is controlled at 2:13:1, and the injection speeds are 6090 m / s and 45 - 70 m / s respectively.

[0050] III. Control and safety system: All nozzle groups are jointly controlled by the PLC control module. Temperature control probes are respectively set 2 meters before and after the nozzle to collect the temperature of the inner wall of the cylinder in real time. The control program dynamically adjusts the hydrogen and oxygen injection flow rates according to the set temperatures of each section to achieve precise control of each temperature zone. At the same time, a hydrogen leakage monitor and a combustion stability analysis module are provided to ensure the safety of high-temperature operation.

[0051] IV. Operating effect: Under the operation of this system, the temperature difference in the rotary kiln temperature zone is controlled within ±20 °C, the main temperature section in the calcination zone is maintained at 1450 ± 10 °C, the crystal form distribution of the clinker is uniform, and the activity index is increased to more than 60%; compared with the traditional pulverized coal combustion method, the unit thermal efficiency is increased by about 18%, the direct carbon dioxide emission of the system is reduced by more than 90%, the zero-carbon calcination goal under continuous operation conditions is achieved, and the lining loss in the high-temperature zone is significantly reduced.

[0052] In terms of catalysts, heterogeneous catalysts with different activity ratios can be selected according to the methanol yield and stability requirements, such as Cu / ZnO / Cr 2 O 3 etc., to optimize the reaction path and extend the service life; the mixed compression unit can be designed as a mixed configuration of centrifugal compression and screw compression to adapt to the volatility of different gas sources; in the condensation and separation link, the pre-stage heat exchange and secondary cooling processes can be added to improve the liquid methanol separation efficiency; in the circulation recovery system, a gas component analysis module can also be added to achieve on-demand adjustment of the circulation ratio and process optimization; this system can also be modularly integrated into cement lines of different scales or other industrial carbon dioxide emission sources to achieve cross-industry carbon resource coupling utilization.

[0053] Carbon dioxide passes through a particulate filter to remove dust particles, and then through an alkaline solution scrubbing tower to remove NO x , SO 2 acid gases. Finally, water vapor is removed through a drying tower, and carbon dioxide gas with a concentration of more than 80% is obtained after purification.

[0054] This embodiment conducts multi-stage purification treatment on the carbon dioxide in the tail gas of the rotary kiln 12; First, the tail gas enters the particulate filter, which adopts a high-efficiency filter element structure and can remove large particulate dust carried in the tail gas to prevent it from causing wear and blockage to subsequent equipment; Then, the tail gas enters the alkaline solution scrubbing tower, and through sufficient contact and reaction with the alkaline solution (such as NaOH, Ca(OH) 2 solution), NO x (nitrogen oxides) and SO 2 (sulfur dioxide) and other acid gas impurities are removed; Subsequently, the tail gas passes through a drying tower, usually filled with silica gel or molecular sieve materials, to further adsorb water vapor and reduce humidity; After the above three treatments, finally, dry and clean carbon dioxide gas with a purity of more than 80% is obtained, which can be safely and stably sent into the methanol synthesis system to participate in the reaction.

[0055] This embodiment effectively improves the purity and stability of carbon dioxide gas through a three-stage purification process, providing ideal raw material conditions for subsequent methanol synthesis; The particulate filter improves the durability and operation safety of the system, the alkaline solution scrubbing significantly reduces the content of acid impurities, prevents catalyst poisoning, and also reduces the corrosiveness of the tail gas; The use of the drying tower reduces the water content in the gas and avoids the adverse effects of water vapor on the reaction process; The entire treatment system is designed compactly and operates stably, which helps to improve the operation efficiency and product quality of the entire energy-carbon coupling system.

[0056] In a possible embodiment, the mixing and compression unit is provided with an automatic proportional regulating valve and a pressure control feedback system for dynamically adjusting the flow ratio of hydrogen to carbon dioxide to match the reaction load.

[0057] This embodiment introduces an intelligent control device in the mixing and compression unit of the methanol synthesis system, including an automatic proportional regulating valve and a pressure control feedback module; Before hydrogen and carbon dioxide gases enter the mixing chamber, they are respectively monitored by flow meters, and their values are uploaded to the central control system in real time; The system automatically adjusts the opening degrees of the two regulating valves according to the set molar ratio (usually 3:1) and the current intake pressure requirement of the methanol reactor to ensure efficient mixing of the gases in the set ratio; At the same time, the pressure feedback system can monitor the output pressure of the compression unit in real time. Once a pressure drop or overpressure signal is detected, it immediately adjusts the operating frequency of the compressor and the state of the regulating valve to ensure that the entire system operates under the best working conditions, improving the synthesis efficiency and reaction stability.

[0058] By introducing an automatic adjustment mechanism, this embodiment effectively solves the problems existing in traditional manual proportioning, such as gas ratio fluctuations and unstable reaction loads; its adaptive adjustment ability not only improves the raw material utilization efficiency, but also significantly enhances the response ability and reliability of the reaction system; under the drive of renewable energy (such as photovoltaic power generation fluctuations), this feedback system can achieve rapid matching adjustment to avoid a decline in reaction efficiency or safety risks; in addition, this system helps to extend the catalyst life, ensure the stable production of methanol, and further improve the overall economy of the system.

[0059] In terms of the selection of the control system, a PLC module or an industrial embedded controller can be used for proportional control and signal feedback analysis, or it can be extended to an optimized control system based on model predictive control (MPC) to enhance the dynamic response and system prediction ability; the type of control valve can be an electric control valve, a pneumatic diaphragm valve or a proportional solenoid valve, and components with appropriate execution speed and control accuracy are selected according to different working conditions; in addition, this system is also applicable to the proportional control of other synthetic reaction gases, such as for the H 2 / N 2 mixing and other scenarios, and has strong versatility and portability.

[0060] In a possible embodiment, the condensation separation unit includes a cooling heat exchanger and a methanol collection tank, and the unreacted gas is cooled and then separated by a gas-liquid separator and discharged into the circulation loop.

[0061] This embodiment optimizes the treatment process of the tail gas after the reaction of the methanol synthesis system; the mixed gas generated by the catalytic reaction first enters the cooling heat exchanger, which exchanges heat with cooling water or other refrigerants to cool the mixed gas to below 25°C, so that the generated methanol is converted from a gaseous state to a liquid state; the cooled gas-liquid mixture flows through the gas-liquid separator, where effective separation of the gas phase and the liquid phase is achieved, and the liquid methanol is introduced into a special methanol collection tank for temporary storage and subsequent purification treatment; the unreacted gas components (mainly hydrogen and carbon dioxide) are introduced into the circulation loop, recompressed and enter the mixed compression unit to participate in a new round of synthesis reaction.

[0062] Through the above condensation separation structure, this embodiment significantly improves the methanol separation efficiency and recovery rate; the cooling heat exchanger ensures that the reaction gas can reach the temperature required for methanol condensation in a short time, effectively precipitating the liquid product; while the gas-liquid separator efficiently separates the gas and liquid phases, ensuring the normal operation of the subsequent recovery system; the setting of the circulation loop not only saves the unreacted raw materials, improves the raw material utilization rate, but also stabilizes the reaction feed composition and maintains the efficient operation state of the system; in addition, this structure is compact in design, stable in operation, and easy to maintain, and is suitable for the requirements of continuous industrial production.

[0063] In a possible implementation, the electrolytic water hydrogen production system is connected to multiple hydrogen injection ports, which are longitudinally distributed along the rotary kiln 12; the system also includes multiple oxygen injection ports to provide auxiliary oxygen around the hydrogen injection ports or into the central cavity of the rotary kiln 12; the control unit is used to monitor the temperature distribution of each section of the rotary kiln in real time and adjust the hydrogen injection flow rate and oxygen supply ratio of each nozzle group to achieve controllable temperature zoning and optimized combustion efficiency; it is applicable to the low-carbon calcination scenario where hydrogen is used as the sole fuel for the rotary kiln, effectively avoiding the risks of local overheating and deflagration.

[0064] In this implementation, multiple hydrogen injection ports are arranged on the body structure of the rotary kiln 12, evenly distributed along the axial direction of the kiln body, and multiple annular oxygen injection ports are arranged in cooperation to achieve multi-region heat supply and oxygen-enriched combustion support; hydrogen and oxygen form local combustion fields in different nozzle combinations, and the system obtains real-time temperature feedback of each area in the kiln through the built-in temperature acquisition module and inputs it into the PID control module for dynamic analysis; the control module adjusts the hydrogen injection flow rate and oxygen ratio of each nozzle according to the set temperature distribution map to ensure the formation of a uniform temperature gradient in the rotary kiln, avoid damage to the furnace lining caused by local high temperature or the deflagration risk brought by too high hydrogen concentration, and improve the overall calcination stability and thermal efficiency.

[0065] This implementation realizes a multi-point, zoned, and intelligent heat supply mode of hydrogen in the rotary kiln, breaks through the limitations of the traditional centralized combustion method, and significantly improves the internal heat field distribution of the kiln; the annular oxygen-supplying structure strengthens the hydrogen combustion reaction rate and flame coverage ability to ensure efficient combustion in a low-carbon fuel environment; by jointly adjusting the combustion parameters in real time through the intelligent control system, it can effectively adapt to the fluctuations of photovoltaic power output, electrolysis load, and calcination load, ensuring continuous and stable production; the system has good thermal control response ability and safety redundancy mechanism, greatly reducing the risk of high-temperature deflagration, enhancing operation safety, and supporting the realization of zero-carbon fuel replacement for the rotary kiln.

[0066] The form of the hydrogen nozzle can be a direct injection type, a diffusion type, or a double-layer nozzle combination according to the diameter of the rotary kiln and process requirements. The oxygen injection port can also choose a central axial injection port or a swirl injection port structure to strengthen the gas mixing effect; in addition to the PID logic, the control module can also introduce fuzzy control or artificial neural network algorithms for dynamic parameter prediction and adjustment to further improve the intelligent level of the system; temperature acquisition can jointly construct a higher-resolution temperature control model through multiple methods such as infrared temperature measurement and thermocouple arrays; this combustion system is also applicable to other high-temperature combustion equipment, such as metallurgical heating furnaces or waste incinerators, to promote the application of low-carbon fuels.

[0067] In a possible implementation, the feed inlet of the second raw material bin 22 is connected to a cement batching system, and the cement batching system includes a clinker finished product bin 19, a fly ash bin 20, and a gypsum bin 21. The discharge outlets of the clinker finished product bin 19, the fly ash bin 20, and the gypsum bin 21 are respectively connected to the feed inlet of the second raw material bin 22.

[0068] In this embodiment, an independent cement batching system is provided at the front end of the cement grinding system, which is used to uniformly convey three main raw materials, namely clinker, fly ash and gypsum, to the second raw material bin 22 in accordance with a set ratio for subsequent grinding treatment by the cement vertical mill 23; the clinker is stored in the clinker finished product bin 19, and the fly ash and gypsum are provided by the fly ash bin 20 and the gypsum bin 21 respectively. A metering feeding device (such as a screw feeder or a vibrating feeder) is provided at the discharge port of each bin and is connected to the second raw material bin 22 through a conveyor; the system can control the raw material ratio and flow rate through the PLC to achieve automatic proportioning, ensure the stability of the raw material composition entering the vertical mill, and meet the product quality standards.

[0069] By setting up a standardized cement batching system, the accuracy and consistency of raw material proportioning can be greatly improved, and the influence of raw material ratio fluctuations caused by manual operation on product performance can be avoided; the independent bin design improves the efficiency of raw material storage and transportation, and is convenient for process adjustment and maintenance management; this system supports flexible adjustment of the proportioning strategy to meet the production requirements of cements with different grades, strengths and uses, and enhances product diversity; the linkage between the equipment configuration and the automatic control system can improve the grinding efficiency and product uniformity, and contribute to the large-scale and stable production of high-quality and low-carbon cement.

[0070] The raw material conveying path can adopt a belt conveyor, pneumatic conveying or chain bucket elevator according to the plant layout to improve the layout flexibility of the system; if it is necessary to expand production capacity or change the cement variety, auxiliary raw material bins such as slag bins and pozzolanic ash bins can also be added, and different proportioning models can be set through programs to meet the needs of new products; flow meters and weighing sensors can be equipped on the discharge devices of each raw material bin to achieve closed-loop automatic control; if there is no fly ash resource, power plant slag, desulfurized gypsum, etc. can also be used as functionally equivalent alternative materials to expand the range of raw material sources and improve the resource utilization efficiency.

[0071] In a possible embodiment, the hot air inlets of the raw material vertical mill 5 and the cement vertical mill 23 are respectively connected to the high-temperature tail gas generated by the rotary kiln 12 calcination system through hot air pipelines; the tail gas is introduced into the vertical mill system through the waste heat conduit as its hot air source, which is used to promote the drying and conveying of the raw material and cement powder. This hot air recovery path not only reduces the overall energy consumption, but also enhances the energy closed-loop coupling effect of the system and further improves the energy efficiency.

[0072] This embodiment makes full use of the waste heat energy of the exhaust gas discharged during the high-temperature calcination process of the rotary kiln 12, and designs a hot air duct to introduce it into the hot air inlets of the raw material vertical mill 5 and the cement vertical mill 23 as the drying heat source required for the grinding process. The exhaust gas is generally in the range of 300-450 °C and has good drying capacity. After entering the vertical mill system, it is mixed with the material to be ground, so that the powder completes the dehydration treatment before or during the grinding process, improving the grinding efficiency and the control ability of the specific surface area of the product. The exhaust gas is treated by a dust removal device before being introduced into the vertical mill to avoid particle pollution and ensure the stable operation of production.

[0073] Through this hot air recovery structure, this embodiment realizes the cascade utilization of the heat energy of the rotary kiln, improves the energy use efficiency, reduces the demand for auxiliary heat sources, and saves fuel and operating costs. While the grinding efficiency is improved, the fluidity of the powder is also enhanced, which helps to improve the stability of the vertical mill system. The integrated energy recovery system has a high degree of automation, reduces energy waste, and promotes the closed-loop operation of heat energy. After being coupled with systems such as photovoltaic-hydrogen production-calcination, it forms a complete thermal-electric-carbon synergy path, helping to build a green and low-carbon manufacturing platform.

[0074] The exhaust gas hot air system can design heat exchangers or intermediate heat storage devices according to different gas components and grinding process requirements to avoid adverse effects on the powder caused by excessive temperature. The hot air duct can be equipped with a multi-channel control system to achieve independent temperature adjustment of the raw material and cement systems and automatically adjust the hot air flow according to the moisture content of the material. When the heat of the exhaust gas is insufficient, an electric heating or gas boiler system can also be used as a supplementary heat source. If a higher drying efficiency is required for the vertical mill system, a staged drying section or a mixed air system can be added to achieve a multi-stage heat utilization structure and further improve the overall heat efficiency and system stability.

[0075] The present invention proposes a low-carbon cement production system that integrates photovoltaic power generation, high-temperature electrolysis, hydrogen combustion, carbon resource utilization, and intelligent control, with significant technological innovation and system synergy advantages. By using photovoltaic power generation as a clean energy source to drive a solid oxide electrolyzer cell (SOEC) to efficiently produce hydrogen with the assistance of the waste heat of the rotary kiln tail gas, the complete substitution of pulverized coal in cement production is achieved, and a zero-carbon calcination path without fossil fuel participation is constructed. The combination of multi-point hydrogen injection and a ring-shaped oxygen-assisted combustion structure with an intelligent temperature control system improves the uniformity and combustion efficiency of the rotary kiln thermal field, ensuring system safety and thermal control accuracy. At the same time, the hydrogen produced by electrolysis and the carbon dioxide by-product gas of the rotary kiln are sent to the methanol synthesis system after multi-stage purification to produce green methanol, promoting the conversion of carbon resources into high-value-added products and forming an energy-carbon closed loop. The supporting intelligent interlocking mechanism realizes dynamic regulation of links such as power generation, hydrogen production, heat supply, and reaction, effectively coping with the volatility of renewable energy and improving system stability and energy efficiency. The overall system has made breakthroughs in aspects such as cascaded energy utilization, raw material resource diversification, and process flow cleaning, with broad industrial adaptability and promotion value, and is a leading-edge integrated technical solution for guiding the green and low-carbon transformation of the cement industry.

[0076] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Without departing from the spirit and scope of the present invention, various changes and modifications can be made to the present invention, and these changes and modifications all fall within the scope of the present invention claimed.

Claims

1. A method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen, characterized in that: A system for producing low-carbon cement by using photovoltaic power generation to produce hydrogen is provided. The system comprises a photovoltaic power generation system, a water electrolysis hydrogen generation system, a raw material grinding system, a rotary kiln calcining system, and a cement grinding system. The photovoltaic power generation system comprises a photovoltaic panel (11), an inverter (10), and a storage battery. The photovoltaic panel (11) is installed on a rainproof canopy of the cement system. The water electrolysis hydrogen generation system comprises an electrolytic cell (13), a hydrogen gas storage tank (14), and an oxygen gas storage tank (15). The electrolytic cell (13) is connected to the hydrogen gas storage tank (14) and the oxygen gas storage tank (15). 4) is connected to an oxygen storage tank (15), the raw material grinding system comprises a raw material bin (4), a raw material vertical mill (5), a dust collector (6), a raw material finished product bin (7) and a chimney (9), the discharge port of the raw material bin (4) is connected to the feed port of the raw material vertical mill (5), the discharge port of the raw material vertical mill (5) is connected to the dust collector (6), the discharge port of the dust collector (6) is connected to the raw material finished product bin (7), the dust outlet of the dust collector (6) is connected to the chimney (9), and the rotary kiln calcining system comprises The invention comprises a cyclone preheater (8), a rotary kiln (12), a grate cooler (16), a second dust collector (17), a second chimney (18) and a clinker finished product warehouse (19). The raw material finished product warehouse (7) is connected to the feed port of the rotary kiln (12) through the cyclone preheater (8). The fuel inlet of the rotary kiln (12) is connected to the hydrogen gas storage tank (14). The discharge port of the rotary kiln (12) is connected to the feed port of the grate cooler (16). The cyclone preheater (8) is connected to the second chimney (18) through the second dust collector (17). The grate cooler ( The discharge port of the raw material bin (16) and the discharge port of the second dust collector (17) are connected to the clinker finished product bin (19), the cement grinding system comprises the second raw material bin (22), the cement vertical mill (23), the third dust collector (24) and the finished product bin (25), the feed port of the second raw material bin (22) is connected to the cement batching system, the discharge port of the second raw material bin (22) is connected to the feed port of the cement vertical mill (23), the cement vertical mill (23) is connected to the finished product bin (25) via the third dust collector (24), and the method comprises the following steps: Step 1: using a photovoltaic panel (11) installed on the rainproof canopy of the cement production line to collect solar energy, and converting it into direct current power through an inverter (10), and the direct current power is used for the water electrolysis hydrogen production system; Step 2: The water electrolysis hydrogen production system electrolyzes water to generate hydrogen and oxygen, wherein the hydrogen is stored in the hydrogen storage tank (14) for standby use, and the oxygen in the oxygen storage tank (15) is used for subsequent calcination and combustion or for sale; Step 3: introducing the hydrogen into the rotary kiln (12) as the only fuel instead of coal powder, and performing efficient combustion through a multi-point combustion structure to achieve a process of calcining raw materials to produce clinker; Step 4: The remaining hydrogen produced in step 2 and the carbon dioxide produced in the rotary kiln calcination system are transported to the methanol synthesis system for reaction to generate green methanol for sale or in-plant use; Step 5: Mix the clinker obtained from the rotary kiln calcination system with fly ash and gypsum auxiliary materials in proportion, and send them into the cement grinding system for grinding to the target specific surface area to obtain a cement product; Step 6: The waste heat from the rotary kiln calcining system and the water electrolysis system is subjected to graded heat exchange through a multi-stage waste heat recovery system, and is used for heating the electrolytic cell, heating the plant area, or for energy supply to other low-temperature process sections; Step 7: Use an intelligent control system to dynamically coordinate the photovoltaic power generation, electrolysis load, hydrogen flow, calcination temperature and methanol synthesis efficiency in steps 1 to 6 to achieve heat-electricity-carbon linkage balance optimization.

2. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 1, characterized in that: The feed inlet of the raw material bin (4) is connected to a batching system, the batching system comprising a limestone bin (1), an iron ore tailings bin (2) and a clay bin (3), and the discharge ports of the limestone bin (1), the iron ore tailings bin (2) and the clay bin (3) are respectively connected to the feed inlet of the raw material bin (4) via conveyors.

3. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 1, characterized in that: The electrolytic cell (13) is a solid oxide electrolytic cell, the operating temperature of the solid oxide electrolytic cell is 600°C-850°C, yttria-stabilized zirconia is used as a solid electrolyte, Ni-YSZ is used as a cathode, and La 1-x Sr x MnO3 is used as the anode, and water vapor is electrolyzed at high temperature to generate hydrogen and oxygen; the high temperature heat of the electrolytic cell (13) is exchanged with the waste heat of the tail gas of the rotary kiln calcining system to provide working heat energy for the water electrolysis hydrogen production system.

4. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 1, characterized in that: The hydrogen storage tank (14) is sent into the methanol synthesis system after being treated by the gas dryer. The carbon dioxide discharged from the tail gas of the rotary kiln (12) is treated and the hydrogen in the hydrogen storage tank (14) is sent into the methanol synthesis system. The methanol synthesis system comprises a mixing compression unit, a catalytic reaction unit, a condensation separation unit and a circulation recovery unit. The mixing compression unit is used to mix hydrogen and carbon dioxide in a molar ratio of 3:1 and compress them to 5-10 MPa; the catalytic reaction unit is a fixed bed reactor filled with a Cu / ZnO / Al2O3 multiphase catalyst, and performs a catalytic synthesis reaction under the conditions of 250°C and 7 MPa; the condensation separation unit is used to cool the reaction product to below 30°C, so that methanol liquid is precipitated and separated from the unreacted gas; the circulation recovery unit is used to return the unreacted gas to the mixing compression unit for circulation reaction.

5. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 4, characterized in that: The carbon dioxide passes through a particle filter to remove dust particles, and then passes through an alkaline washing tower to remove NO x , SO2 acidic gas; finally, water vapor is removed through a drying tower; after purification, carbon dioxide gas with a concentration of more than 80% is obtained.

6. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 4, characterized in that: The mixing compression unit is equipped with an automatic proportional control valve and a pressure control feedback system to dynamically adjust the flow ratio of hydrogen and carbon dioxide to match the reaction load.

7. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 4, characterized in that: The condensation separation unit includes a cooling heat exchanger and a methanol collection tank. The unreacted gas is cooled, separated by a gas-liquid separator, and then discharged into a circulation loop.

8. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 1, characterized in that: The water electrolysis hydrogen production system is connected to a plurality of hydrogen injection ports, which are distributed longitudinally along the rotary kiln (12); the water electrolysis hydrogen production system is provided with a plurality of oxygen injection ports, which provide auxiliary oxygen around the hydrogen injection ports or to the central cavity of the rotary kiln (12).

9. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 1, characterized in that: The feed inlet of the second raw material bin (22) is connected to a cement batching system, the cement batching system comprising a clinker finished product bin (19), a fly ash bin (20) and a gypsum bin (21), and the discharge ports of the clinker finished product bin (19), the fly ash bin (20) and the gypsum bin (21) are respectively connected to the feed inlet of the second raw material bin (22).

10. The method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen according to claim 1, characterized in that: The hot air inlets of the material vertical mill (5) and the cement vertical mill (23) are respectively connected to the high-temperature tail gas generated by the calcining system of the rotary kiln (12) through hot air ducts.

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