A system and method for producing low-carbon cement using photovoltaic electricity to produce hydrogen

Abstract

The application discloses a kind of hydrogen production low-carbon cement system and method using photovoltaic power generation, the system includes photovoltaic power generation system, electrolytic water hydrogen production system, raw material grinding system, rotary kiln calcination system, cement grinding system and carbon resource utilization device;Photovoltaic system provides clean power for electrolytic device, and hydrogen is efficiently prepared at high temperature using solid oxide electrolytic cell;Hydrogen is input into rotary kiln as the only fuel by multi-point injection and oxygen combustion-supporting structure, realizing zero carbon emission of cement calcination process;Carbon dioxide in system tail gas is synthesized into methanol after purification together with hydrogen, and energy-carbon cycle closed loop path is constructed;Through multistage waste heat recovery and intelligent control system, the linkage optimization of photovoltaic output, electrolysis load, calcination heat intensity and carbon conversion efficiency is realized;The application has significant advantages in improving energy utilization efficiency, reducing carbon emission, promoting resource coordination and intelligent control, and is suitable for the construction of new green cement industrial platform.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of low-carbon cement production, in particular to a system and method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen. BACKGROUND

[0002] According to the current status of cement production in China, cement production is one of the main sources of global carbon emissions, accounting for about 8% of global anthropogenic carbon dioxide emissions, and the 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, a 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, and the prepared clinker is mixed with fly ash, gypsum and other materials, and then ground to form cement; the large use of coal powder as calcination fuel not only has high carbon emissions, but also is difficult to realize dynamic energy consumption control, thereby restricting the development of green manufacturing. Various technologies have been explored in the industry, including hydrogen energy replacing coal, photovoltaic power supply, carbon capture and resource utilization.

[0003] Patent No. CN117069401A discloses a zero-carbon emission cement production device and method based on hydrogen energy utilization, which 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 the carbon dioxide byproduct gas through a methanol synthesis system; the advantages of this scheme are: without greatly modifying the existing cement production line, the use of coal is reduced, and partial carbon emission reduction is achieved. However, the 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 emission reduction range is limited; and the hydrogen used in the system is obtained by methanol reforming, and there is still an indirect emission problem of fossil energy. Patent No. CN218915948U discloses a system for realizing zero-carbon emission of a cement plant by using renewable green hydrogen, which uses photovoltaic or wind energy as the energy source, produces hydrogen and oxygen by electrolyzing water, supplies hydrogen to the cement rotary kiln for burning, and captures carbon dioxide in the tail gas and synthesizes methanol with hydrogen to realize carbon resource utilization. However, the energy scheduling strategy between the sub-systems is not optimized, for example, there is a lack of coordination mechanism between photovoltaic output and electrolysis load, and hydrogen supply load, which makes it difficult to adapt to the energy efficiency stability problem caused by renewable energy fluctuation, resulting in the need to improve the system operation efficiency.

[0004] Patent publication CN115961294A discloses a zero-carbon emission carbon-based chemical product preparation system and method. Hydrogen is produced by renewable energy power generation driving water electrolysis system, and carbon dioxide in carbon-containing flue gas is captured. Hydrogen or water reacts under electrocatalysis / thermal catalysis conditions to synthesize carbon-based chemical products such as methanol and ethanol. The existing technology is mainly applied to general platform type structures of carbon emission industries such as chemical industry, power industry and steel industry. The system construction is not customized designed for the production chain characteristics of the cement industry. There are 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 and cement grinding. Patent publication numbers CN117563407A, CN116478014A and CN117175679A also have the above problems.

[0005] In summary, although the prior art attempts to introduce hydrogen energy and renewable energy into the field of cement production to achieve a certain degree of carbon reduction or carbon cycle, the following technical problems have not been effectively solved:

[0006] The traditional hydrogen replacement coal technology still adopts a partial replacement scheme, which cannot achieve zero carbonization of the rotary kiln. The photovoltaic renewable energy system has large fluctuation. The carbon dioxide resourceization path is single, and a multi-functional energy closed-loop system coupled with hydrogen energy has not been formed. The waste heat and surplus energy utilization efficiency is not high, and the energy cascade utilization and production line energy closed loop have not been fully realized.

[0007] Therefore, an integrated technical solution is needed that combines photovoltaic hydrogen production, intelligent commissioning, hydrogen full replacement combustion, carbon dioxide resource recycling and multi-stage energy recovery. It can not only achieve zero carbon emission of the rotary kiln full process, but also has excellent energy efficiency regulation capability, and adapts to the new energy dominated green cement manufacturing trend. SUMMARY

[0008] The technical problem to be solved by the present application is to overcome the existing defects and provide a low-carbon cement production system and method using photovoltaic power generation to produce hydrogen. A comprehensive system integrating photovoltaic power generation, SOEC high-efficiency electrolysis, hydrogen partition combustion, carbon dioxide methanol synthesis and intelligent control is constructed to form a complete "energy-carbon linkage closed loop". The system not only realizes zero coal powder and zero carbon emission fuel replacement in the rotary kiln calcination process, but also drives the electrolytic cell by tail gas waste heat and produces high-purity hydrogen and oxygen, significantly improving energy utilization efficiency, and effectively solving the problems in the background technology.

[0009] To achieve the above object, the present application provides the following technical scheme: a system and method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen, comprising a system for producing low-carbon cement by using photovoltaic power generation to produce hydrogen, which is composed 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 comprises photovoltaic panels, an inverter and a storage battery; the photovoltaic panels are installed on a rain shelter of the cement system; the rain shelter is mainly used for rain protection of equipment or key components on the cement production line; the photovoltaic panels are replaced by photovoltaic panels to convert solar energy into electric energy and realize clean energy utilization; the electric energy collected by the photovoltaic panels is converted into direct current electric energy by the inverter and stored in the storage battery; the water electrolysis hydrogen production system comprises an electrolytic cell, a hydrogen storage tank and an oxygen storage tank; the electrolytic cell is connected with the hydrogen storage tank and the oxygen storage tank respectively; water in the electrolytic cell is electrolyzed by electric energy in the storage battery to generate hydrogen and oxygen which are stored in the hydrogen storage tank and the oxygen storage tank respectively; the raw material grinding system is composed of a raw material bin one, a raw material vertical mill, a dust collector one, a raw material finished product bin and a chimney one; the discharge port of the raw material bin one is connected with the feed port of the raw material vertical mill; the discharge port of the raw material vertical mill is connected with the dust collector one; the discharge port of the dust collector one is connected with the raw material finished product bin; and the dust outlet of the dust collector one is connected with the chimney one; the main function of the raw material vertical mill is to grind raw material with a particle size of ≤50 mm into powdery material with a size of about 80 μm; the rotary kiln calcination system comprises a cyclone preheater, a rotary kiln, a grate cooler, a dust collector two, a chimney two and a clinker finished product bin; the raw material finished product bin is connected with the feed port of the rotary kiln through the cyclone preheater; the fuel inlet of the rotary kiln is connected with the hydrogen storage tank; the discharge port of the rotary kiln is connected with the feed port of the grate cooler; the cyclone preheater is connected with the chimney two through the dust collector two; and the discharge port of the grate cooler and the discharge port of the dust collector two are connected with 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 with a size of 80 μm, which can be used as a kind of cement raw material; and the cement grinding system comprises a raw material bin two, a cement vertical mill, a dust collector three and a finished product bin; the feed port of the raw material bin two is connected with a cement batching system; the discharge port of the raw material bin two is connected with the feed port of the cement vertical mill; and the cement vertical mill is connected with the finished product bin through the dust collector three; the main function of the cement grinding system is to proportion and grind clinker, fly ash, gypsum and other materials to the finished product with a specific surface area of 3300-3800 cm² / g, which is cement; and the method comprises the following steps:

[0010] Step one: collecting solar energy by using photovoltaic panels arranged on the rain shelter of the cement production line and converting the solar energy into direct current electric energy by using an inverter; and the direct current electric energy is used for the water electrolysis hydrogen production system;

[0011] Step two: electrolyzing water by using the water electrolysis hydrogen production system to generate hydrogen and oxygen; the hydrogen is stored in a hydrogen storage tank for standby use; and the oxygen is stored in an oxygen storage tank for subsequent calcination combustion or sale;

[0012] Step three: hydrogen gas instead of coal powder is used as the only fuel into the rotary kiln, and high-efficiency combustion is realized through a multi-point combustion structure to realize the process of generating clinker by calcining raw materials;

[0013] Step four: the residual hydrogen gas generated in step two and the carbon dioxide generated in the rotary kiln calcining system are transported to the methanol synthesis system for reaction to generate green methanol for sale or in-plant use;

[0014] Step five: the clinker obtained from the rotary kiln calcining system is mixed with fly ash and gypsum auxiliary materials in a certain proportion and sent to the cement grinding system for grinding to the target specific surface area to obtain cement finished products;

[0015] Step six: the waste heat of the rotary kiln calcining system and the electrolysis water system is exchanged through a multi-stage waste heat recovery system, and is used for heating the electrolytic cell, heating the plant, or supplying energy to other low-temperature process sections;

[0016] Step seven: the intelligent control system is used to dynamically adjust the photovoltaic power generation, electrolysis load, hydrogen flow, calcination temperature, and methanol synthesis efficiency in steps one to six to realize the balance optimization of heat-electricity-carbon linkage.

[0017] Further, the feeding port of the raw material bin one is connected with a batching system, the batching system includes a limestone bin, an iron ore tailings bin and a clay bin, and the discharge ports of the limestone bin, the iron ore tailings bin and the clay bin are connected with the feeding port of the raw material bin one through conveyors.

[0018] Further, the electrolytic cell is a solid oxide electrolytic cell, the working temperature of the solid oxide electrolytic cell is 600-850℃, yttria-stabilized zirconia is used as the solid electrolyte, Ni-YSZ is used as the cathode, La 1-x SrxMnO3 is used as the anode, and hydrogen and oxygen are generated by electrolyzing water vapor at high temperature; the rotary kiln tail gas temperature is generally 300-450℃, and can reach 600-850℃ after heat exchange; the stable working interval of the solid oxide electrolytic cell is exactly 600-850℃, which is naturally matched with the system heat source, and no additional heating energy is needed; the high-temperature heating of the electrolytic cell is realized by heat exchange with the rotary kiln calcining system tail gas waste heat to provide working heat energy for the water electrolysis hydrogen production system; the solid oxide electrolytic cell uses reaction heat to assist water decomposition, has the lowest power consumption, and produces high-purity hydrogen and oxygen, and the electrolysis efficiency is significantly higher than that of the normal temperature electrolysis method, is suitable for the rotary kiln tail gas waste heat temperature zone, and the material system has mature process, fast response, and good industrial adaptability and popularization.

[0019] Further, the hydrogen storage tank is connected to a gas dryer, and the carbon dioxide discharged from the rotary kiln is connected to the hydrogen storage tank via the gas dryer. The mixed compression unit is used to mix hydrogen and carbon dioxide at a molar ratio of 3:1 and compress them to 5-10 MPa. The catalytic reaction unit is a fixed bed reactor filled with Cu / ZnO / Al2O3 heterogeneous catalyst, and the catalytic synthesis reaction is carried out at 250°C and 7 MPa. The condensation separation unit is used to cool the reaction products to below 30°C to separate the unreacted gas from the methanol liquid. The recycling unit is used to recycle the unreacted gas to the mixed compression unit for recycling reaction.

[0020] Further, the carbon dioxide is filtered through a particle filter to remove dust particles, then washed through an alkali washing tower to remove NOx and SO2 acidic gases, and finally dried through a drying tower to remove water vapor. After purification, a carbon dioxide gas with a concentration of more than 80% is obtained.

[0021] Further, the mixed compression unit is provided 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.

[0022] Further, the condensation separation unit includes a cooling heat exchanger and a methanol collection tank. The unreacted gas is cooled and separated by a gas-liquid separator before being discharged into the recycling loop.

[0023] Further, the electrolytic water hydrogen production system is connected to multiple hydrogen injection ports, which are distributed along the longitudinal direction of the rotary kiln. The electrolytic water hydrogen production system is also connected to multiple oxygen injection ports, which provide auxiliary oxygen around the hydrogen injection ports or in the central cavity of the rotary kiln. A 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 temperature zoning control and combustion efficiency optimization. This system is suitable for low-carbon calcination scenarios where hydrogen is the only fuel for the rotary kiln, effectively avoiding the risk of local overheating and deflagration.

[0024] The preparation unit includes a temperature acquisition module, a PID control module, and a flow control module. The control logic includes adjusting the hydrogen / oxygen ratio and opening sequence based on feedback from different temperature zones. This intelligent control system is used to achieve energy-carbon resource coordinated regulation and operation optimization under fluctuating conditions such as photovoltaic output, electrolysis load, rotary kiln heating, and carbon dioxide production.

[0025] By setting multiple hydrogen injection ports on the rotary kiln cylinder and introducing auxiliary oxygen, multi-region independent heating and efficient mixing combustion are realized, the temperature distribution is significantly optimized, the uniformity and stability of the calcination process are improved, and the risk of local overheating and deflagration caused by traditional centralized injection is effectively avoided; at the same time, the oxygen-assisted mode improves the combustion efficiency and flame coverage of hydrogen, ensuring efficient, controllable and zero-carbon emission calcination process without relying on fossil fuels, and has good system safety and low-carbon collaborative application value.

[0026] Further, the feed inlet of the second raw material bin is connected with a cement batching system, the cement batching system includes a clinker finished product bin, a fly ash bin and a gypsum bin, and the discharge outlets of the clinker finished product bin, the fly ash bin and the gypsum bin are respectively connected with the feed inlet of the second raw material bin.

[0027] Further, the hot air inlets of the raw material vertical mill and the cement vertical mill are respectively connected with the high-temperature tail gas generated by the rotary kiln calcination system through hot air pipelines; the high-temperature tail gas is introduced into the vertical mill system through a waste heat conduit as a hot air source for promoting the drying and conveying of raw materials 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.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] By using this technology, "two grinding and one burning" can be realized, i.e., grinding raw materials, burning clinker and grinding cement, and the coal powder grinding link can be cancelled; green electricity is generated by photovoltaic power generation, hydrogen is generated by electrolysis of water, and the fuel of the rotary kiln equipment is changed from coal powder to hydrogen energy, which can directly realize zero carbon emission of fuel combustion in this link; at the same time, due to the cancellation of the coal powder grinding link, carbon emission in this link can be directly eliminated, thereby achieving the purpose of low-carbon cement production.

[0030] 2. By constructing an energy system based on photovoltaic power generation and high-temperature water electrolysis hydrogen production, the rotary kiln calcination process is completely replaced by hydrogen instead of coal powder as the only heat source for the first time, which breaks the dependence on fossil fuels in the traditional cement production process; in the traditional process, coal powder calcination not only has high carbon emission intensity, but also has the problems of inflexible combustion adjustment and local overheating; compared with the prior art, high-purity hydrogen is used as fuel, and uniform combustion is realized under the cooperation of multiple-point nozzle oxygen assistance, which significantly reduces the risk of carbon emission and heat loss; the cancellation of the coal grinding link can further reduce carbon emission, equipment maintenance and dust pollution, and promote the development of the cement industry towards zero-carbon fuel replacement from the system structure.

[0031] 3、The core technology path is to realize the whole-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 tail gas waste heat reuse; wherein, the heat source of the SOEC high temperature electrolysis module is directly derived from the rotary kiln tail gas, and the hydrogen production mode without additional heating is realized through heat exchange; the vertical mill system also uses the tail gas as the hot air source, which improves the energy closed loop level; the captured carbon dioxide is further used for synthesizing methanol, which not only reduces greenhouse gas emissions, but also generates high value-added products, realizing the transformation and utilization of carbon resources; the whole system constitutes a complete cycle from energy input to heat-carbon conversion to material output, significantly improving the energy comprehensive utilization efficiency and environmental friendliness.

[0032] 4、In the calcination link, the application proposes a multi-point hydrogen injection and annular oxygen assisting heating scheme, combined with an intelligent temperature control module, to realize independent regulation and dynamic adjustment of each section of the rotary kiln; compared with the traditional centralized combustion mode, the structure greatly reduces the risk of local overheating and unstable flame, improves the combustion uniformity and system safety. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 The figure is a schematic diagram of the system of the application;

[0034] Fig. 2 The figure is a schematic diagram of the methanol synthesis system of the application.

[0035] In the figure: 1 limestone warehouse, 2 iron ore tailings warehouse, 3 clay warehouse, 4 raw material warehouse I, 5 raw material vertical mill, 6 dust collector I, 7 raw material finished product warehouse, 8 cyclone preheater, 9 chimney I, 10 inverter, 11 photovoltaic panel, 12 rotary kiln, 13 electrolytic cell, 14 hydrogen storage tank, 15 oxygen storage tank, 16 grate cooler, 17 dust collector II, 18 chimney II, 19 clinker finished product warehouse, 20 fly ash warehouse, 21 gypsum warehouse, 22 raw material warehouse II, 23 cement vertical mill, 24 dust collector III, 25 finished product warehouse. DETAILED DESCRIPTION

[0036] In the description of the application, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the application. Example one

[0037] Please refer to Figs. 1-2The application provides a technical scheme: a system and method for producing low-carbon cement by using photovoltaic power generation to produce hydrogen, comprising a system for producing low-carbon cement by using photovoltaic power generation to produce hydrogen, which is composed 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 is composed of photovoltaic panels 11 installed on a rainproof shed of the cement system, an inverter 10 and a storage battery; the photovoltaic panels 11 collect solar energy, convert the electric energy through the inverter 10 and store the electric energy in the storage battery; the water electrolysis hydrogen production system is composed of a water electrolysis tank 13, a hydrogen storage tank 14 and an oxygen storage tank 15; the water electrolysis tank 13 decomposes water into hydrogen and oxygen after being electrified, and the hydrogen and the oxygen are stored in the hydrogen storage tank 14 and the oxygen storage tank 15 respectively; 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; raw materials are ground through the raw material vertical mill 5 from the raw material bin 4, treated through the dust collector 6 and finally stored in the raw material finished product bin 7, and dust is discharged through the chimney 9; the rotary kiln calcination system is composed of a cyclone preheater 8, a rotary kiln 12, a grate cooler 16, a dust collector 17, a chimney 18 and a clinker finished product bin 19; raw materials are preheated through the cyclone preheater 8 and then enter the rotary kiln 12 for calcination, the required fuel is hydrogen supplied by the hydrogen storage tank 14, and the produced clinker is cooled through the grate cooler 16 and then enters the clinker finished product bin 19; flue gas is treated through the dust collector 17 and then discharged from the chimney 18; the cement grinding system is composed of a raw material bin 22, a cement vertical mill 23, a dust collector 24 and a finished product bin 25; clinker, fly ash and gypsum are mixed and then ground to produce cement products with a specific surface area of 3300-3800 cm² / g; the method comprises seven steps in sequence: solar energy collection and power supply, water electrolysis hydrogen production, hydrogen fuel calcination, hydrogen and carbon dioxide for methanol production, finished cement production, multi-stage waste heat recovery and intelligent control joint debugging.

[0038] In this embodiment, the photovoltaic panels 11 replace the conventional rainproof shed materials, solar energy is converted into electric energy, the electric energy is stored in the storage battery through the inverter 10 and then used to supply the water electrolysis tank 13 for water electrolysis reaction to produce high-purity hydrogen and oxygen; hydrogen is used as the only fuel of the rotary kiln 12, enters the calcination zone through a multi-point fuel injection system to realize efficient and uniform combustion, raw materials are converted into clinker through high-temperature reaction in the rotary kiln 12, are cooled through the grate cooler 16 and are stored in the clinker finished product bin 19; by-product oxygen is used for combustion support or sold externally; waste heat is used for electrolytic cell heating and plant power supply through heat exchange to improve energy efficiency; meanwhile, hydrogen produced by electrolysis and carbon dioxide in the calcination tail gas are jointly sent into a methanol synthesis device to generate green methanol, forming an energy-carbon coupling closed loop; in addition, an intelligent control system monitors parameters of each process node in real time, dynamically adjusts photovoltaic output, electrolysis load, hydrogen flow and combustion temperature, and realizes heat-electricity-carbon balance linkage.

[0039] Compared with the traditional cement production method, the system cancels the coal powder preparation and combustion link, realizes complete decarburization in the calcination process, improves the electrolysis efficiency by using high-temperature electrolysis technology, and effectively utilizes the rotary kiln tail gas waste heat as an electrolysis heat source, thereby significantly reducing energy consumption. The intelligent control system ensures the collaborative operation of each link, improves the energy conversion efficiency and the recycling rate of carbon resources, and realizes clean energy driving and low carbon emission in the whole process of cement production, thereby promoting the development of the industry towards green manufacturing.

[0040] In the above scheme, the photovoltaic panel 11 can also be installed on the top surface of other buildings in the factory area, further expanding the clean energy utilization area; the electrolytic water pool 13 can be replaced by an alkaline electrolytic cell or a proton exchange membrane system, although the power consumption is relatively high, but the equipment structure is simpler, suitable for small and medium-sized scenes.

[0041] In a possible implementation, the raw material bin one 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, and the discharge ports of the limestone bin 1, the iron ore tailings bin 2 and the clay bin 3 are respectively connected with the feeding port of the raw material bin one 4 through conveyors.

[0042] This embodiment adds a special batching system at the front end of the raw material grinding system, which is used for pre-proportioning and conveying the main raw materials such as limestone, iron ore tailings and clay required for cement production; the limestone bin 1, the iron ore tailings bin 2 and the clay bin 3 serve as raw material storage units, and automatic discharge devices are arranged below them, and conveyors are used to convey different proportions of raw materials into the raw material bin one 4 respectively to complete unified feeding, and then the raw materials are sent into the raw material vertical mill 5 for grinding treatment; this batching system can realize continuous and stable material supply, and through controlling the discharge rate and sequence, it can ensure that the proportion of each type of raw material meets the preset process requirements.

[0043] By setting a special batching system, this embodiment significantly improves the accuracy and automation level of raw material supply, effectively avoiding the proportioning error and stability problem caused by manual proportioning; at the same time, using the conveyor for automatic feeding can reduce material loss and dust pollution, and improve the overall operation efficiency; in particular, using iron ore tailings as raw materials not only realizes the resource utilization of solid waste, but also reduces the cost of raw materials, and improves the environmental friendliness and resource utilization rate of the system; in addition, the batching system is highly matched with the downstream vertical mill system, which ensures the continuous and stable operation of the subsequent grinding process, and helps to improve the overall operation efficiency of the cement production line.

[0044] In the above scheme, the discharge structures of limestone bin 1, iron ore tailings bin 2, and clay bin 3 can adopt various methods such as vibrating feeders, screw conveyors, or gravity sliding pipes to adapt to the physical characteristics and process requirements of different raw materials. In terms of conveying equipment, belt conveyors, pneumatic conveyors, or chain conveyor devices can be adopted according to the production line layout to improve the flexibility of deployment. In some resource-constrained areas, iron ore tailings can also be replaced with other rich iron slag or high-iron ore powder to achieve 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 PLC programs to achieve higher precision intelligent batching control.

[0045] In one possible implementation, the water electrolysis cell 13 is a solid oxide electrolysis cell, with an operating temperature of 600℃-850℃, using yttrium-stabilized zirconium oxide as the solid electrolyte, Ni-YSZ as the cathode, and La1- X SrxMnO3 serves as the anode, electrolyzing water vapor to generate hydrogen and oxygen under high-temperature conditions. The exhaust temperature of the rotary kiln is generally between 300℃ and 450℃, but can reach 600℃ to 850℃ after heat exchange. Its temperature range matches that of the electrolysis cell. The high-temperature heating of the water electrolysis cell 13 provides working heat energy for the water electrolysis hydrogen production system by exchanging heat with the waste heat of the exhaust gas from the rotary kiln calcination system.

[0046] This embodiment uses a solid oxide electrolyzer (SOEC) as the core device for hydrogen production through water electrolysis. This electrolyzer utilizes the reaction between water vapor and the solid electrolyte interface at high temperature to generate hydrogen and oxygen. The core material system of the SOEC includes a Ni-YSZ composite cathode, a YSZ ceramic electrolyte layer, and La1- X The SrxMnO3 anode can operate stably in the range of 600℃-850℃. Since the exhaust gas temperature of the rotary kiln 12 is between 300℃ and 450℃, it can reach the temperature range required by SOEC after being heated by the efficient heat exchange structure. Therefore, no additional heating energy is required to maintain the temperature of the electrolytic cell. The system introduces the heat energy of the rotary kiln exhaust gas into the electrolytic cell through the heat exchanger to realize the recovery and utilization of heat energy. At the same time, it 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 or sold industrially.

[0047] The SOEC module includes: an electrolytic cell body, composed of a multi-layer series structure, with each electrolysis unit using the following material configuration:

[0048] Cathode: A Ni-YSZ composite material is used, with YSZ (yttrium-stabilized zirconium oxide) having a mass fraction of 50% and nickel powder having a particle size of 1-3 μm. The composite structure electrode layer is prepared by co-firing and has good electron-oxygen ion dual conductivity and porous structure, which is conducive to the reaction of water vapor on the electrode surface to generate hydrogen.

[0049] Electrolyte layer: YSZ (yttria-stabilized zirconia) ceramic sheet with a thickness of 50-100 μm, high oxygen ion mobility, stable performance in the temperature range of 600-850°C;

[0050] Anode: La 0.8 Sr 0.2 MnO3 as the main material, prepare perovskite conductive ceramic, coated on the other side of the electrolyte and sintered at high temperature to form a dense layer, used for oxygen ion electron emission to form oxygen;

[0051] Heating and thermal coupling structure: The electrolysis cell module is provided with an independent heat preservation shell, and the cement rotary kiln tail gas passes through the heat exchanger coil at the lower part of the shell to exchange heat. After heat exchange, the internal temperature of the SOEC is maintained in the range of 720°C-780°C, without the need for external electric heating.

[0052] Photovoltaic power supply system interface: In this embodiment, the SOEC module is connected to the output end of the photovoltaic inverter through a direct current bus, and a dynamic voltage stabilization control strategy is adopted. When the photovoltaic solar radiation is strong and the power generation is high, the maximum power point tracking (MPPT) power supply is carried out to drive the SOEC system to carry out efficient water vapor electrolysis.

[0053] Steam input and gas output path:

[0054] The water source is recycled water in the plant, which is heated to 250°C by a multi-stage evaporation heating system and then input into the SOEC module;

[0055] The hydrogen product is directly introduced into the hydrogen storage tank 14 and used for the rotary kiln calcination fuel system;

[0056] The byproduct oxygen is dehydrated and then enters the oxygen storage tank 15, which can be used for the rotary kiln combustion support system or sold externally.

[0057] Under the above structure, the SOEC module has an average hydrogen production rate of 0.36 Nm³ / h, an average hydrogen production of 0.03 Nm³ per kilowatt of photovoltaic power, a hydrogen production efficiency of 82%, an increase of about 30% compared with normal temperature electrolysis, and good system stability.

[0058] Compared with traditional alkaline electrolysis cells (AEC) or proton exchange membrane electrolysis systems (PEM), the solid oxide electrolysis cell (SOEC) system adopted in the present application has higher thermal energy adaptability and energy conversion efficiency; its high temperature operation characteristic enables it to fully utilize the tail gas waste heat generated in the cement production process, reduces the overall energy consumption of the system, simultaneously realizes high-purity hydrogen output, is more suitable for industrial-grade hydrogen calcination demand, and has the advantages of long-term operation stability, low equipment corrosion risk, and low operation and maintenance cost.

[0059] In practical applications, the SOEC module can adopt a single-cell series or multi-group parallel structure, and be flexibly configured according to the hydrogen production scale; if the heat of the tail gas is insufficient, electric heating or a high-temperature heat storage system can also be used to stabilize the SOEC operating temperature; the electrolyte material can be replaced by other ceramic materials with high oxygen ion conductivity, such as GDC (gadolinium-doped ceria) or LSGM (strontium-doped lanthanum strontium molybdenum oxide) to improve the conductivity; in terms of power supply interface, the SOEC can also be connected to wind power, geothermal energy and other renewable energy power sources to realize multi-energy coupling 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, and improves the system adaptability and flexible deployment capability.

[0060] In one possible implementation, the hydrogen gas tank 14 is sent to the methanol synthesis system after being treated by the gas dryer, and the carbon dioxide discharged from the rotary kiln 12 is sent to the methanol synthesis system after being treated, together with the hydrogen treated 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 the hydrogen and the carbon dioxide at a molar ratio of 3:1 and compress them to 5-10 MPa; the catalytic reaction unit is a fixed bed reactor, which is internally filled with Cu / ZnO / Al2O3 heterogeneous catalyst, and performs catalytic synthesis reaction under the condition of 250°C and 7 MPa; the condensation and separation unit cools the product to below 30°C to precipitate methanol; and the recycling unit is used to send the unreacted gas back to the mixing and compression unit for recycling.

[0061] In this embodiment, the hydrogen is derived from a solid oxide electrolysis cell (SOEC), and the carbon dioxide is derived from the rotary kiln calcination tail gas, both of which are synthesized into methanol after catalytic reaction, realizing an integrated path of "carbon capture-conversion-utilization".

[0062] I. Raw gas acquisition and pretreatment:

[0063] Hydrogen source: high-purity hydrogen continuously produced by the SOEC system, with a purity of more than 99.99%, which is sent to the methanol synthesis system after being treated by the gas dryer;

[0064] Carbon dioxide source: a branch is set on the rotary kiln 12 exhaust pipeline, which is pretreated by the following devices: particle filter: removes dust particles;

[0065] Alkaline washing tower: removes NOx, SO2 and other acidic gases;

[0066] Drying tower: removes water vapor; after purification, carbon dioxide gas with a concentration of more than 80% is obtained.

[0067] II. Mixing and pressurization:

[0068] Hydrogen and carbon dioxide gas are mixed at a molar ratio of 3:1, enter the three-stage compression system through the gas mixing device, pressurized to 7.0 MPa, and preheated to 180°C before entering the reactor.

[0069] III. Catalytic reaction section:

[0070] The mixed gas enters the fixed-bed catalytic reactor, which is filled with Cu / ZnO / Al2O3 catalyst (particle size 2-3 mm, bulk density 0.8 g / cm³) inside. The reaction conditions are set as:

[0071] Reaction temperature: 250°C; reaction pressure: 7.0 MPa; residence time: about 1.5 seconds;

[0072] Under these conditions, the conversion rate of hydrogen and carbon dioxide is stable, the methanol generation rate is 0.45 kg / h, and the byproduct steam enters the condensation section with the gas stream.

[0073] IV. Product cooling and separation:

[0074] The reaction tail gas is cooled to 25°C by the shell cooler and enters the collection tank through the gas-liquid separator. The liquid components are methanol with purity ≥98% and a small amount of water, which are collected after distillation to obtain pure methanol product. The main components of the unreacted gas are hydrogen, carbon dioxide and a small amount of carbon monoxide, which are compressed and returned to the gas mixing section for recycling.

[0075] V. Intelligent control and energy synergy:

[0076] The system is equipped with a temperature-pressure double feedback control system to adjust the feed ratio, reaction temperature and circulation flow rate, and is connected with the photovoltaic power generation, electrolytic hydrogen production and rotary kiln temperature control modules of the main system to realize multi-source joint debugging.

[0077] VI. Implementation effect:

[0078] The system has been continuously running for 72 hours, with a methanol yield of 38% and a hydrogen utilization rate of about 85%. It realizes the partial sequestration and utilization of carbon dioxide in the cement production process, and converts green hydrogen into high-value chemicals, with good energy efficiency and economic potential.

[0079] In this embodiment, the hydrogen heating system is used to replace the traditional coal or natural gas heating method, and a clean, safe and low-carbon calcination heat source path is constructed.

[0080] I. Configuration of hydrogen injection and oxygen assisting device:

[0081] Rotary kiln body: the rotary kiln used has a diameter of 3.5 m and a length of 58 m, with a lining of refractory material inside the cylinder.

[0082] Nozzle arrangement: Nine sets of hydrogen-oxygen injection nozzles are set along the length of the kiln body, with a spacing of 6m;

[0083] Each group of nozzles includes one central hydrogen nozzle and three to four annular oxygen nozzles, forming a coaxial circulation structure.

[0084] The nozzle is made of 625 alloy material, which can withstand temperatures up to 1100℃, and is equipped with a water-cooling jacket.

[0085] Injection angle and layout: The central hydrogen injection port is tilted at an angle of 20°-30°, facing the direction of material propulsion;

[0086] The annular oxygen nozzles are arranged around the main nozzle to form a localized oxygen-rich mixing zone.

[0087] II. Gas supply system parameter settings:

[0088] Hydrogen source: continuously supplied by the SOEC system at a pressure of 0.8 MPa with a purity greater than 99.99%, and supplied to each nozzle through branch pressure-stabilizing pipelines;

[0089] Oxygen source: partly by-product oxygen from SOEC, and partly supplied by a low-pressure liquid oxygen system; oxygen injection pressure is 0.5 MPa.

[0090] Mixing ratio and injection speed: The hydrogen / oxygen volume ratio of each group of nozzles is controlled at 2:13:1, and the injection speeds are 6090 m / s and 45-70 m / s, respectively.

[0091] III. Control and Safety Systems:

[0092] All nozzle groups are controlled by a PLC control module;

[0093] Temperature control probes are set 2 meters before and after the nozzle to collect the temperature of the inner wall of the cylinder in real time.

[0094] The control program dynamically adjusts the hydrogen and oxygen injection flow rates according to the temperature settings of each segment, thereby achieving precise control of each temperature zone.

[0095] It is also equipped with a hydrogen leak detector and a combustion stability analysis module to ensure safe operation at high temperatures.

[0096] IV. Operational Results:

[0097] Under the operation of this system, the temperature difference in the rotary kiln temperature zone is controlled within ±20℃, the main temperature section of the calcination zone is maintained at 1450±10℃, the clinker crystal distribution is uniform, and the activity index is increased to over 60%. Compared with the traditional pulverized coal combustion method, the unit thermal efficiency is increased by about 18%, the direct carbon dioxide emissions of the system are reduced by more than 90%, the zero-carbon calcination target under continuous operation conditions is achieved, and the furnace lining wear in the high-temperature zone is significantly reduced.

[0098] In terms of catalysts, different multi-phase catalysts with different activity ratios can be selected according to the methanol yield and stability requirements, such as Cu / ZnO / Cr2O3, 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, a front-stage heat exchange and secondary cooling process can be added to improve the separation efficiency of liquid methanol; in the recycling system, a gas component analysis module can also be added to realize on-demand adjustment of the recycling ratio and process optimization; the system can also be modularly integrated into different scale cement lines or other industrial carbon dioxide emission sources to realize cross-industry carbon resource coupling utilization.

[0099] The carbon dioxide passes through a particle filter to remove dust particles, then passes through an alkali washing tower to remove NOx and SO2 acidic gases, and finally passes through a drying tower to remove water vapor, and after purification, carbon dioxide gas with a concentration of more than 80% is obtained.

[0100] This embodiment performs multi-stage purification treatment on the carbon dioxide in the tail gas of the rotary kiln 12; first, the tail gas enters the particle filter, which adopts a high-efficiency filter core structure, capable of removing large particles of dust carried in the tail gas, preventing it from causing wear and blockage to subsequent equipment; then, the tail gas enters the alkali washing tower, and through sufficient contact reaction with alkaline solution (such as NaOH, Ca(OH)2 solution), removes acidic gas impurities such as NOx (nitrogen oxides) and SO2 (sulfur dioxide) therein; subsequently, the tail gas passes through the drying tower, usually filled with silica gel or molecular sieve material, further adsorbing water vapor to reduce humidity; after the above three treatments, dry and clean carbon dioxide gas with a purity of more than 80% is finally obtained, which can be safely and stably sent into the methanol synthesis system to participate in the reaction.

[0101] 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 particle filter improves the durability and operational safety of the system, the alkali washing significantly reduces the content of acidic impurities, preventing catalyst poisoning, and also reduces the corrosiveness of the tail gas; the use of the drying tower reduces the water content in the gas, avoiding the adverse effects of water vapor on the reaction process; the entire treatment system is compact in design and stable in operation, which helps to improve the operational efficiency and product quality of the entire carbon coupling system.

[0102] In one possible implementation, the mixed compression unit is provided with an automatic proportioning valve and a pressure control feedback system for dynamically adjusting the flow ratio of hydrogen and carbon dioxide to match the reaction load.

[0103] The embodiment introduces an intelligent control device in the mixed compression unit of the methanol synthesis system, including an automatic proportional regulating valve and a pressure control feedback module; the hydrogen and carbon dioxide gas are monitored by flow meters before entering the mixing cavity, and the values are uploaded to the central control system in real time; the system automatically adjusts the opening of the two regulating valves according to the set molar ratio (usually 3:1) and the current gas inlet pressure requirement of the methanol reactor, to ensure efficient mixing of the gas according to the set ratio; at the same time, the pressure feedback system can monitor the output pressure of the compression unit in real time, and immediately adjust the compressor operating frequency and the regulating valve state once the pressure drop or overpressure signal is detected, to ensure that the entire system operates under optimal conditions, improving synthesis efficiency and reaction stability.

[0104] By introducing an automatic adjusting mechanism, the embodiment effectively solves the problems of gas ratio fluctuation and unstable reaction load in traditional manual proportioning; its self-adaptive adjusting capability not only improves the raw material utilization efficiency, but also significantly enhances the response capability and reliability of the reaction system; under the driving of renewable energy (such as photovoltaic power fluctuation), the feedback system can realize rapid matching adjustment to avoid reaction efficiency decline or safety risk; in addition, the system helps to prolong the catalyst life, ensure the stability of methanol production, and further improve the overall economy of the system.

[0105] In the selection of the control system, PLC modules or industrial embedded controllers can be used for proportional control and signal feedback analysis, or an optimization control system based on model predictive control (MPC) can be extended to improve dynamic response and system prediction capability; the regulating valve type can be an electric regulating valve, a pneumatic diaphragm valve or a proportional electromagnetic valve, and components with adaptive execution speed and control precision are selected according to different working conditions; in addition, the system is also suitable for proportion control of other synthesis reaction gases, such as H2 / N2 mixing for ammonia synthesis, and has strong universality and portability.

[0106] In one possible embodiment, the condensation separation unit includes a cooling heat exchanger and a methanol collection tank, and the unreacted gas is discharged into the circulation loop after being separated by a gas-liquid separator after cooling.

[0107] The embodiment optimizes the treatment process of the tail gas of the methanol synthesis system after reaction; the mixed gas generated by the catalytic reaction first enters the cooling heat exchanger, which cools the mixed gas to below 25°C through heat exchange with cooling water or other refrigerants, so that the methanol generated is converted from gas to liquid; the gas-liquid mixture after cooling flows through a gas-liquid separator, where the gas phase and the liquid phase are effectively separated, and the liquid methanol is guided into a dedicated methanol collection tank for temporary storage and subsequent purification treatment; the unreacted gas components (mainly hydrogen and carbon dioxide) are guided into the circulation loop, re-compressed and entered into the mixed compression unit to participate in a new round of synthesis reaction.

[0108] By the above condensing separation structure, the methanol separation efficiency and recovery rate are significantly improved; the cooling heat exchanger ensures that the reaction gas can reach the temperature required for methanol condensation in a short time, effectively precipitating liquid products; and the gas-liquid separator efficiently separates the gas-liquid two-phase, ensuring the normal operation of the subsequent recovery system; the setting of the circulation loop not only saves unconverted raw materials, improves the utilization rate of raw materials, but also stabilizes the composition of the reaction feed, maintaining the high-efficiency operation state of the system; in addition, the structure is compact in design, stable in operation, easy to maintain, and suitable for continuous industrial production requirements.

[0109] In one possible implementation, the water electrolysis hydrogen production system is connected to multiple hydrogen injection ports, which are distributed longitudinally along the rotary kiln 12; the system also includes multiple oxygen injection ports to provide auxiliary oxygen around the hydrogen injection ports or in the central cavity of the rotary kiln 12; a 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 optimize combustion efficiency; it is suitable for low-carbon calcination scenarios where hydrogen is used as the only fuel for the rotary kiln, effectively avoiding the risk of local overheating and deflagration.

[0110] This implementation arranges multiple hydrogen injection ports on the rotary kiln 12 body structure, uniformly distributed along the kiln body axis, and cooperates with multiple annular oxygen injection ports to achieve multi-zone heating and oxygen-enriched combustion; hydrogen and oxygen form a local combustion field in different nozzle groups, and the system obtains real-time temperature feedback from each region 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 diagram to ensure the formation of uniform temperature gradient in the rotary kiln, avoid the risk of deflagration caused by local high temperature or excessive hydrogen concentration, and improve the overall calcination stability and thermal efficiency.

[0111] This implementation realizes a multi-point, zoned, and intelligent heating mode of hydrogen in the rotary kiln, breaks through the limitations of traditional centralized combustion, and significantly improves the heat distribution in the kiln; the annular oxygen-assisted structure enhances the hydrogen combustion reaction rate and flame coverage capacity, ensuring efficient combustion in a low-carbon fuel environment; the intelligent control system adjusts the combustion parameters in real time, effectively adapting to fluctuations in photovoltaic output, electrolysis load, and calcination load, and ensuring continuous and stable production; the system has good thermal control response capability and safety redundancy mechanism, significantly reduces the risk of high-temperature deflagration, enhances operational safety, and supports the realization of zero-carbon fuel replacement for rotary kilns.

[0112] The hydrogen nozzle form can adopt a straight injection type, a diffusion type or a double-layer nozzle combination according to the diameter of the rotary kiln and the process requirements, and the oxygen nozzle can also select a central axial nozzle or a cyclone nozzle 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 algorithm for dynamic parameter prediction and adjustment, further improving the intelligent level of the system; temperature collection can be cooperatively constructed by multiple ways such as infrared temperature measurement and thermocouple array to build a higher resolution temperature control model; the combustion system is also applicable to other high-temperature combustion equipment such as metallurgical heating furnaces or waste incinerators, to realize the popularization and application of low-carbon fuels.

[0113] In one possible implementation, the feed inlet of the second raw material bin 22 is connected with a cement proportioning system, which includes a clinker finished product bin 19, a fly ash bin 20 and a gypsum bin 21, and the discharge outlets of the clinker finished product bin 19, the fly ash bin 20 and the gypsum bin 21 are respectively connected with the feed inlet of the second raw material bin 22.

[0114] This implementation sets an independent cement proportioning system at the front end of the cement grinding system, which is used to uniformly deliver the three main raw materials, i.e. clinker, fly ash and gypsum, according to the set proportion to the second raw material bin 22 for subsequent cement vertical mill 23 for grinding treatment; the clinker is stored in the clinker finished product bin 19, the fly ash and the gypsum are respectively provided by the fly ash bin 20 and the gypsum bin 21, and each bin discharge outlet is provided with a quantitative feeding device (such as a screw feeder or a vibrating feeder) and is connected with the second raw material bin 22 through a conveyor; the system can control the raw material proportion and flow through PLC to realize automatic proportioning, ensure the stability of the raw material composition entering the vertical mill, and meet the product quality standards.

[0115] By setting a standardized cement proportioning system, the accuracy and consistency of the raw material proportioning can be greatly improved, and the product performance can be affected by the fluctuation of the raw material proportion caused by manual operation; the independent bin design improves the raw material storage and transportation efficiency, and facilitates process adjustment and maintenance management; the system supports flexible adjustment of the proportioning strategy to meet the cement production needs of different grades, strengths and purposes, and enhances product diversity; the linkage of equipment configuration and automatic control system can improve the grinding efficiency and product uniformity, and help realize the large-scale stable production of high-quality low-carbon cement.

[0116] The raw material conveying path can adopt a belt conveyor, pneumatic conveying or chain bucket elevator according to the plant layout, and the lifting system is flexible; if the capacity needs to be expanded or the cement variety needs to be changed, auxiliary raw material bins such as slag bin and volcanic ash bin can also be added, and different proportioning models can be set through the program to adapt to new product demands; the discharge device of each raw material bin can be equipped with a flowmeter and a weighing sensor to realize closed-loop automatic control; if there is no fly ash resource, power plant slag, desulfurization gypsum and other functionally equivalent alternative materials can also be used to expand the raw material source range and improve the resource utilization efficiency.

[0117] In a possible implementation, 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 calcination system of the rotary kiln 12 through hot air pipelines; the tail gas is introduced into the vertical mill system through a waste heat conduit as a hot air source for promoting the drying and conveying of the raw material and the 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 the energy efficiency.

[0118] This implementation fully utilizes the tail gas heat energy discharged by the rotary kiln 12 during high-temperature calcination, and designs a hot air conduit to introduce it into the hot air inlets of the raw material vertical mill 5 and the cement vertical mill 23 as a drying heat source required for the grinding process. The tail gas generally ranges from 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 grinding, improving the grinding efficiency and the control ability of the specific surface area of the product. The tail gas is treated by a dust removal device before being introduced into the vertical mill to avoid particle pollution and ensure stable production operation.

[0119] Through this hot air recovery structure, this implementation realizes the step-by-step utilization of the heat energy of the rotary kiln, improves the energy use efficiency, reduces the demand for auxiliary heat sources, saves fuel and operating costs, and improves the grinding efficiency while enhancing the flowability of the powder, 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 closed-loop operation of heat energy. When coupled with a photovoltaic-hydrogen-calcination system, it forms a complete thermal-electric-carbon collaborative path, helping to build a green and low-carbon manufacturing platform.

[0120] The tail gas hot air system can design a heat exchanger or an intermediate heat storage device according to different gas compositions and grinding process requirements to avoid adverse effects of excessively high temperature on the powder. The hot air conduit can be provided with a multi-channel control system to realize 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 tail gas is insufficient, an electric heating or gas boiler system can be used as a supplementary heat source. If the vertical mill system needs to achieve higher drying efficiency, a staged drying section or a mixed air system can be added to realize a multi-stage heat utilization structure, further improving the overall thermal efficiency and system stability.

[0121] The application proposes a low-carbon cement production system integrating photovoltaic power generation, high-temperature electrolysis, hydrogen combustion, carbon resourceization and intelligent control, which has significant technical innovation and system synergy advantages; by taking photovoltaic power generation as a clean energy source, solid oxide electrolysis cell (SOEC) is driven to produce hydrogen efficiently under the assistance of rotary kiln tail gas waste heat, realizing the complete replacement of coal powder in cement production and building a zero-carbon calcination path without fossil fuel participation; the combination of multi-point hydrogen injection and annular oxygen-assisted combustion structure with an intelligent temperature control system improves the uniformity and combustion efficiency of the rotary kiln heat field, ensuring system safety and thermal control precision; at the same time, the hydrogen produced by electrolysis and the carbon dioxide by-product gas from the rotary kiln are sent to the methanol synthesis system after multi-stage purification to generate green methanol, promoting the conversion of carbon resources to high-value-added products and forming an energy-carbon closed loop; the matching intelligent joint control mechanism realizes dynamic adjustment of power generation, hydrogen production, heat supply and reaction links, effectively coping with the volatility of renewable energy, improving system stability and energy efficiency; the overall system has made breakthroughs in energy cascade utilization, raw material resource diversification and clean process flow, has wide industrial adaptability and promotion value, and is a leading integrated technology solution leading the green and low-carbon transformation of the cement industry.

[0122] The basic principles, main features and advantages of the application are shown and described above, and the application has various changes and improvements without departing from the spirit and scope of the application, which fall within the scope of the application.

Claims

1. A method for producing low-carbon cement by hydrogen production using photovoltaic power generation, characterized by: The application relates to a low-carbon cement production system using photovoltaic power generation and hydrogen production, which is composed 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 comprises photovoltaic panels (11), an inverter (10) and a storage battery, the photovoltaic panels (11) are installed on a rainproof shed of the cement system, the water electrolysis hydrogen production system comprises an electrolytic cell (13), a hydrogen storage tank (14) and an oxygen storage tank (15), the electrolytic cell (13) is connected with the hydrogen storage tank (14) and the oxygen storage tank (15) respectively, 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 with the feeding port of the raw material vertical mill (5), the discharge port of the raw material vertical mill (5) is connected with the dust collector (6), the discharge port of the dust collector (6) is connected with the raw material finished product bin (7), and the dust outlet of the dust collector (6) is connected with the chimney (9), the rotary kiln calcination system comprises a cyclone preheater (8), a rotary kiln (12), a grate cooler (16), a dust collector (17), a chimney (18) and a clinker finished product bin (19), the raw material finished product bin (7) is connected with the feeding port of the rotary kiln (12) through the cyclone preheater (8), the fuel inlet of the rotary kiln (12) is connected with the hydrogen storage tank (14), the discharge port of the rotary kiln (12) is connected with the feeding port of the grate cooler (16), the cyclone preheater (8) is connected with the chimney (18) through the dust collector (17), and the discharge port of the grate cooler (16) and the discharge port of the dust collector (17) are connected with the clinker finished product bin (19), the cement grinding system comprises a raw material bin (22), a cement vertical mill (23), a dust collector (24) and a finished product bin (25), the feeding port of the raw material bin (22) is connected with a cement batching system, the discharge port of the raw material bin (22) is connected with the feeding port of the cement vertical mill (23), and the cement vertical mill (23) is connected with the finished product bin (25) through the dust collector (24), the electrolytic cell (13) is a solid oxide electrolytic cell, the working temperature of the solid oxide electrolytic cell is 600-850 DEG C, yttrium-stabilized zirconia is used as the solid electrolyte, Ni-YSZ is used as the cathode, and La 1-x SrxMnO3 is used as the anode, and water vapor is electrolyzed to generate hydrogen and oxygen at high temperature. The high-temperature heat supply of the electrolytic cell (13) is provided by heat exchange with the tail gas waste heat of the rotary kiln calcination system, thereby providing working heat energy for the water electrolysis hydrogen production system; the SOEC module comprises: an electrolytic cell main body composed of a multi-layer series structure, each electrolytic unit adopts the following material configuration: Cathode: a Ni-YSZ composite material is used, the mass fraction of YSZ (yttria-stabilized zirconia) is 50%, the particle size of nickel powder is 1-3 μm, and the composite structure electrode layer is prepared by co-firing, which has good electron-oxygen ion double conductivity and porous structure, and is beneficial to the reaction of water vapor on the electrode surface to generate hydrogen; Electrolyte layer: YSZ (yttria-stabilized zirconia) ceramic sheet is used, which has high oxygen ion mobility and stable working performance in the temperature range of 600-850°C; Anode: La 0.8 Sr 0.2 MnO3 as the main material, to prepare perovskite conductive ceramic, coated on the other side of the electrolyte and high temperature sintering to form a dense layer, for oxygen ion release electron oxygen; Heating and thermal coupling structure: the electrolytic cell module is provided with an independent heat preservation shell, and the tail end flue gas of the cement rotary kiln passes through the heat exchanger coil at the lower part of the shell for heat exchange, and the internal temperature of the SOEC is maintained in the range of 720-780°C after heat exchange, without the need for external electric heating; Photovoltaic power supply system interface: the SOEC module is connected to the output end of the photovoltaic inverter through a direct current bus, and a dynamic voltage stabilization control strategy is adopted to perform maximum power point tracking (MPPT) power supply when the sunlight is strong and the power generation capacity is high, thereby driving the SOEC system to carry out efficient water vapor electrolysis; The hydrogen storage tank (14) is sent to the methanol synthesis system after being treated by a gas dryer, the carbon dioxide discharged from the rotary kiln (12) is sent to the methanol synthesis system after being treated, and the hydrogen in the hydrogen storage tank (14) treated by the gas dryer is sent to the methanol synthesis system, the methanol synthesis system comprises a mixing and compression unit, a catalytic reaction unit, a condensation and separation unit and a circulation and recovery unit, the mixing and compression unit is used for mixing hydrogen and carbon dioxide at a molar ratio of 3:1 and compressing to 5-10 MPa; the catalytic reaction unit is a fixed bed reactor filled with Cu / ZnO / Al2O3 heterogeneous catalyst, and the catalytic synthesis reaction is carried out under the condition of 250°C and 7 MPa; the condensation and separation unit is used for cooling the reaction product to below 30°C, so that methanol liquid is separated from unreacted gas; and the circulation and recovery unit is used for recycling the unreacted gas to the mixing and compression unit for circulation reaction; The method comprises the following steps: Step one: solar energy is collected by the photovoltaic panel (11) arranged on the rainproof shed of the cement production line, and converted into direct current electric energy by the inverter (10), and the direct current electric energy is used for the water electrolysis hydrogen production system; Step two: the water electrolysis hydrogen production system electrolyzes water to generate hydrogen and oxygen, the hydrogen is stored in the hydrogen storage tank (14) for standby, and the oxygen is stored in the oxygen storage tank (15) for subsequent calcination combustion or sale; Step three: the hydrogen is used as the only fuel instead of coal powder and introduced into the rotary kiln (12) through a multi-point fuel injection structure for efficient combustion, thereby realizing the process of calcining raw materials to generate clinker; Step four: the remaining hydrogen generated in step two and the carbon dioxide generated in the rotary kiln calcination system are transported to the methanol synthesis system for reaction to generate green methanol for sale or use in the factory. Step five: mix the clinker obtained from the rotary kiln calcination system with fly ash and gypsum according to the proportion, and send it into the cement grinding system to grind to the target specific surface area to obtain the cement product; Step six: the waste heat from the rotary kiln calcination system and the electrolytic water system is exchanged through a multi-stage waste heat recovery system, and is used for heating the electrolytic cell, heating the plant area or other low-temperature process section; Step seven: use an intelligent control system to dynamically adjust the photovoltaic power generation, electrolytic load, hydrogen flow, calcination temperature and methanol synthesis efficiency in steps one to six, to realize the balance optimization of heat-electricity-carbon linkage.

2. The method for producing low-carbon cement by hydrogen production using photovoltaic power generation according to claim 1, characterized in that: The feeding port of the raw material bin one (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), and the discharge ports of the limestone bin (1), the iron ore tailings bin (2) and the clay bin (3) are respectively connected with the feeding port of the raw material bin one (4) through conveyors.

3. The method for producing low-carbon cement by hydrogen production using photovoltaic power generation according to claim 1, characterized in that: The carbon dioxide passes through a particle filter to remove dust particles, then passes through an alkali washing tower to remove NOx and SO2 acidic gases, and finally passes through a drying tower to remove water vapor; after purification, carbon dioxide gas with a concentration of more than 80% is obtained.

4. The method for producing low-carbon cement by hydrogen production using photovoltaic power generation according to claim 3, characterized in that: The mixed compression unit is provided 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.

5. The method for producing low-carbon cement by hydrogen production using photovoltaic power generation according to claim 1, characterized in that: The condensation separation unit includes a cooling heat exchanger and a methanol collection tank, and the unreacted gas is separated by a gas-liquid separator after cooling and then discharged into the circulation loop.

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

7. The method for producing low-carbon cement by hydrogen production using photovoltaic power generation according to claim 1, characterized in that: The feeding port of the raw material bin two (22) is connected with a cement batching system, the cement batching system includes a clinker product bin (19), a fly ash bin (20) and a gypsum bin (21), and the discharge ports of the clinker product bin (19), the fly ash bin (20) and the gypsum bin (21) are respectively connected with the feeding port of the raw material bin two (22).

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

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