Low-carbon cement production method for co-producing high-value chemicals

Abstract

The invention discloses a low-carbon cement production method for co-producing high-value chemicals, which adopts actual ingredients for cement production to produce cement clinker, fully considers the influence of impurity components in cement raw materials on follow-up synthesis, preheats the raw materials in a preheating separator I and a preheating separator II step by step, avoids advanced decomposition, and improves the production efficiency. The maximum in-situ reaction of in-situ CO2 and H2 is ensured, and harmful elements such as sulfur and chlorine are converted into the oxygen-enriched gas in advance and do not enter the subsequent synthesis step, so that the gas purification cost is reduced; a part of hydrogen is recycled, so that the problem that the conversion rate of the reverse water-gas shift reaction is relatively low is solved, CO2 is converted into carbon monoxide to the greatest extent, and subsequent synthesis of high-value chemicals is facilitated. According to the invention, low-carbon production of the cement clinker can be realized, CO2 generated by carbonate decomposition is completely converted into high-value chemicals, carbon emission in the cement industry can be reduced by more than 50%, gas and heat generated in each step are fully utilized, and utilization of resources and heat is realized to the greatest extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental engineering, and particularly relates to a low-carbon cement production method for co-producing high-value chemicals. Background Art

[0002] The cement industry, as the cornerstone of the construction industry, occupies a crucial position in the global economy. The energy consumption and chemical reactions during cement production release a large amount of CO2, which has a non-negligible impact on global warming. Different from other industries, the CO2 emissions in the cement industry are divided into direct carbon emissions (emissions from fossil fuel combustion and process emissions during cement production) and indirect carbon emissions (emissions generated from electricity consumption during cement production). For different types of cement, the proportion of fuel combustion and electricity carbon emissions in the total carbon emissions during cement production fluctuates little. Among them, the carbon emissions from fuel combustion account for about 30%, and the carbon emissions from electricity account for about 10%. The carbonate decomposition process is the main carbon emission source during cement production and also the main factor affecting the difference in carbon emissions of different cements. Currently, the main paths for carbon emission reduction in the cement industry include: 1. The ultimate energy efficiency improvement of existing process equipment; 2. Low-carbon cement technologies based on raw material substitution; 3. Fuel substitution for the coal combustion emissions problem in the calcination process; 4. Carbon capture, utilization, and storage (CCUS) for end-of-pipe treatment. However, due to the particularity of cement production, a large amount of CO2 will still be inevitably generated during the production process. Exploring economic and efficient CO2 emission reduction technologies is of great significance in the cement industry. If a cement production process for in-situ conversion and utilization of CO2 can be developed, the carbon emission reduction during cement production can be minimized to provide technical support for the cement industry to achieve carbon neutrality at an early date.

[0003] The effective integration of CO2 capture and conversion utilization (CCU) is another attractive strategy to reduce anthropogenic CO2 emissions while realizing the potential benefits of CO2 molecules. If the CO2 generated from carbonate decomposition during cement production can be catalytically converted and utilized, it will be an effective technology for the cement industry to achieve carbon peak and carbon emission reduction.

[0004] In 1968, Giardini et al. reported interesting observations on the reaction of CaCO3, MgCO3, and dolomite with pressurized H2 to produce hydrocarbons. Wang Zhengyi et al. also reported that CaCO3, as a CO2 source, could be directly converted into CH4 and C1-C3 hydrocarbons in an H2 atmosphere. The above reports indicate that the direct conversion and utilization of CO2 in carbonates is feasible. In an H2 atmosphere, the reduction of CO2 by carbonates not only avoids the capture, transportation, and storage of CO2 but also improves the overall energy efficiency by coupling two endothermic reactions within the same temperature window. However, the above studies only demonstrated the feasibility of carbonate hydrogenation and did not explore carbon emission reduction in combination with the cement process, nor did they introduce the use of the reduced CO2. It does not have the value of being applied and promoted in the cement industry.

[0005] Chinese Patent Publication No. CN118954980A discloses a method for hydrogen refining of bimetallic carbonate dolomite, and CN117446756A discloses a method for inducing low-temperature hydrogen refining of carbonate by mechanochemical pretreatment. These two inventions only involve the most basic chemical reactions and are not coupled with the cement production process. Chinese Patent Publication No. CN115895707A discloses a method and system for the high-value utilization of carbon dioxide decomposed from carbonate. This system is also not combined with the cement production process, does not consider the general raw meal in the cement industry, does not produce cement products, and introduces the CO2 decomposed from carbonate into the catalytic reaction bed, adding multiple additional devices. Chinese Patent Publication No. CN118908260A discloses a method and system for zero-carbon decomposition of carbonate hydrogenation reduction based on hydrogen combustion self-heating, CN118491466A discloses an in-situ hydrogen refining device for carbonate, CN113582208A discloses a method for producing syngas by hydrogen refining of carbonate for carbon dioxide emission reduction, and CN118387838A discloses a process for directly hydrogenating and decomposing and reducing carbonate catalyzed by iron-containing solid waste. These inventions also do not consider the general raw meal in the cement industry, do not produce cement products, and do not mention how to utilize the produced carbon monoxide. Moreover, CN118908260A uses hydrogen as fuel, wasting precious hydrogen resources, increasing the water vapor content in the products, and adding an extra burden to subsequent chemical synthesis. Chinese Patent Publication No. CN118831526A discloses a low-carbon production system and method for producing metal oxides and methanol from hydrogen-assisted carbonate, and CN117566775A discloses a method for hydrogen refining of magnesium carbonate to produce magnesium oxide and co-produce methanol. These two inventions mention using carbonate hydrogenation to prepare methane and carbon monoxide and reacting with excess hydrogen to synthesize methanol, but they do not consider the actual cement production process. Currently, the cost of hydrogen is relatively high, and using hydrogen to synthesize methanol has the problem of too high cost.

[0006] In summary, the existing cement industry still has the following problems in the catalytic conversion and utilization of CO2:

[0007] (1) A large amount of CO2 is generated during both coal combustion and carbonate decomposition in the cement industry. The existing solutions have not completely solved the problem of CO2 conversion and utilization;

[0008] (2) None of the existing solutions use the actual raw material batching of the cement process, and the types of carbonates used are relatively single;

[0009] (3) Most of the existing solutions do not mention how to utilize the generated carbon monoxide, or only mention using carbon monoxide to prepare methanol, with low added value of the product and waste of hydrogen resources;

[0010] (4) When using the existing solutions to synthesize high-value chemicals subsequently, due to the presence of harmful elements such as sulfur, chlorine, and fluorine in the cement raw meal, it will cause poisoning of the subsequent synthesis catalyst, so the purification cost of the product gas is relatively high;

[0011] (5) None of the existing technical solutions for carbonate hydrogenation are combined with the actual cement production process. Adopting the above relevant literature requires a complete transformation of the existing cement plants. Under the current background of the downturn in the cement industry, a practical carbonate hydrogenation conversion solution for the cement industry has not been proposed.

[0012] Therefore, with the gradual implementation of the dual-carbon policy, it is urgent to find a technical route suitable for CO2 emission reduction through catalytic conversion and utilization in the cement industry. Summary of the Invention

[0013] In view of the problems existing in the prior art, the present invention provides a low-carbon cement production method for co-producing high-value chemicals. By using this production method for in-situ hydrogenation of carbonates, the carbon dioxide in the carbonates can be converted and utilized, and finally high-value chemicals can be synthesized, significantly reducing carbon emissions during cement production. The existing cement production equipment can be transformed to maximize the utilization of heat and materials within the cement production system.

[0014] The present invention is implemented as follows. A cement production method for co-producing high-value chemicals includes the following steps:

[0015] First, an electrolytic water device is used to prepare hydrogen and oxygen; oxygen and air enter a mixed gas storage tank for mixing to form oxygen-rich air I. Oxygen-rich air I enters a grate cooler for preheating and is discharged from the middle section of the grate cooler to obtain oxygen-rich air II;

[0016] The raw meal enters a preheating and separating device I, exchanges heat and performs gas-solid separation with the tail gas V discharged from the rear section of the grate cooler. After the raw meal is preheated to a certain temperature, it enters a preheating and separating device II. The tail gas VII discharged from the preheating and separating device I enters a waste heat power generation device;

[0017] The oxygen-rich air II enters the preheating separator II and exchanges heat with the in-furnace raw material therein. After forming the preheated raw material, it enters the catalytic reaction device. The oxygen-rich air III discharged from the preheating separator II is divided into oxygen-rich air IV and oxygen-rich air V. Among them, the oxygen-rich air IV enters the rotary kiln, and the oxygen-rich air V enters the waste heat power generation device;

[0018] Hydrogen enters the heat exchange device I and exchanges heat with the mixed gas I in the discharge gas separator to form preheated hydrogen I; The preheated hydrogen I enters the hydrogen mixing device and is mixed with the preheated hydrogen II discharged from the heat exchange device II to obtain preheated hydrogen III at a certain temperature, and then enters the catalytic reaction device;

[0019] In the catalytic reaction device, the preheated raw material and the preheated hydrogen III move in the same direction and are fully mixed and reacted. The material-gas mixture enters the material-gas separator; The pre-calcined raw material after separation enters the rotary kiln, and the mixed gas I enters the heat exchange device I;

[0020] The mixed gas II discharged from the heat exchange device I enters the water removal and purification device. After being dewatered and purified, the mixed gas III enters the synthesis device. After being pressurized and heated, high-value chemicals and separated and recycled hydrogen are obtained by separation. The separated and recycled hydrogen enters the heat exchange device II;

[0021] Pulverized coal enters the rotary kiln and is mixed with the oxygen-rich air IV for combustion. The combustion heat is used for firing the pre-calcined raw material. After firing, the clinker enters the grate cooler for cooling to form the cooled clinker product; The tail gas I generated in the rotary kiln enters the heat exchange device II and exchanges heat with the separated and recycled hydrogen. The tail gas I is initially cooled to become the tail gas II, and then enters the waste heat power generation device; The separated and recycled hydrogen is heated up to become the preheated hydrogen II and enters the hydrogen mixing device;

[0022] The tail gas III discharged from the waste heat power generation device enters the dust removal, desulfurization and denitration purification device, and then forms pure tail gas; A part of the pure tail gas is discharged through the chimney, and the other part enters the section of the grate cooler far from the rotary kiln for preliminary preheating to form the tail gas V and enters the preheating separator I.

[0023] Preferably, the volume fraction of oxygen in the oxygen-rich air I is 28% - 45%; The temperature of the oxygen-rich air II is 580 - 600 °C, and the temperature of the tail gas V is 260 - 290 °C.

[0024] Preferably, the raw material is mixed with a reverse water gas shift reaction catalyst. The temperature of the raw material and catalyst mixture is 60 - 80 °C, and the particle size range is 10 - 100 μm; The mass of the catalyst accounts for 5% - 15% of the total mass of the mixture;

[0025] The main components of the catalyst are steel slag, carbide slag, manganese slag and other solid wastes, which are obtained after reduction at a certain temperature. Among them, the temperature is 450 °C - 650 °C, and the reduction time is 0.5 - 2 h.

[0026] Preferably, the preheating temperature of the raw meal exiting the first preheating separator is 110 - 170°C, and the temperature of the seventh tail gas exiting the first preheating separator is 110 - 170°C;

[0027] Preferably, the temperatures of the oxygen - enriched air three and the preheated raw meal exiting the second preheating separator are 390 - 450°C respectively; where the oxygen - enriched air three is a gas containing sulfur and chlorine - based pollutants.

[0028] Preferably, the temperature of the preheated hydrogen one exiting the first heat - exchange device is 550°C - 590°C, and the temperature of the preheated hydrogen two exiting the second heat - exchange device is 650 - 750°C.

[0029] Preferably, the reaction temperature in the catalytic reaction device is 550 - 750°C, the raw meal decomposition rate ≥ 95%, and the CO2 conversion rate ≥ 90%; the heating form of the catalytic reaction device is one or a combination of electric heating, microwave heating, and light - wave heating.

[0030] Preferably, the temperatures of the pre - decomposed raw meal and the first mixed gas exiting the outlet gas separator are 580 - 700°C; the first mixed gas mainly consists of water vapor, CO, CO2, and H2, where the water vapor concentration ≥ 15%, the ratio of CO to CO2 concentration is 9 - 20, and the ratio of CO to H2 concentration is 0.1 - 0.5; the temperature of the second mixed gas is 130 - 170°C; the water vapor concentration in the third mixed gas ≤ 5%, the ratio of CO to CO2 concentration is 9 - 20, and the ratio of CO to H2 concentration is 0.1 - 0.5.

[0031] Preferably, the pressure in the synthesis device is 0.1MPa - 1.5MPa, and the reaction temperature is 200 - 350°C; the high - value chemicals are alkanes, α - olefins, dimethyl carbonate, and lower alcohols.

[0032] Preferably, the temperature of the first tail gas is 1050 - 1200°C, the temperature of the separated and recycled hydrogen is 30 - 50°C; the temperature of the second tail gas is 380 - 460°C.

[0033] Preferably, the temperature of the third tail gas exiting the waste heat power generation device is 60 - 80°C; the electric energy generated by the waste heat power generation device goes to the electrolytic water device.

[0034] The advantages and positive effects of the present invention are:

[0035] (1) The present invention can achieve low - carbon production of cement clinker, completely convert the CO2 generated by carbonate decomposition into high - value chemicals, and can reduce the carbon emissions in the cement industry by more than 50%.

[0036] (2) The present invention couples cement production and chemical synthesis to produce high - value chemical products, fully utilizes the gases and heat generated in each step, and maximally realizes the utilization of resources and heat.

[0037] (3) The present invention uses the actual batching in cement production to produce cement clinker, fully considering the influence of impurity components in cement raw meal on subsequent synthesis. The raw meal is preheated step by step in the first and second preheating separators to avoid premature decomposition, ensuring the in-situ reaction of in-situ CO2 and H2 to the greatest extent. Harmful elements such as sulfur and chlorine are converted into oxygen-rich gas in the first preheating separator and the second preheating separator in advance and do not enter the subsequent synthesis steps, reducing the gas purification cost.

[0038] (4) The present invention combines with the existing cement production process, makes the most use of the existing equipment in the cement plant, can be reformed on the existing cement production line, and proposes a practical carbonate hydrogenation conversion scheme for the cement industry.

[0039] (5) The present invention recycles a part of hydrogen, solves the problem of low conversion rate of the reverse water gas shift reaction, and converts CO2 into carbon monoxide to the greatest extent, which is beneficial to the subsequent synthesis of high-value chemicals.

[0040] (6) The present invention uses solid waste such as steel slag as part of the reforming catalyst, which can realize the utilization of some solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flowchart of the low-carbon cement production method for co-producing high-value chemicals provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0044] Embodiment

[0045] The following elaborates in detail the specific working process of the present invention:

[0046] An embodiment of the present invention provides a cement production method for co-producing high-value chemicals. This production method is achieved through the following equipment: an electrolytic water device, a hydrogen storage tank, an oxygen storage tank, a flow meter, an air compressor, a grate cooler, a preheating separator, a catalytic reaction device, a material-gas separator, a rotary kiln, a heat exchange device, a water removal and purification separation device, a Fischer-Tropsch synthesis device, a separation device, a hydrogen mixing device, a waste heat power generation device, a purification device, a chimney, etc. In addition, it also includes some control systems, pipelines, valves, etc.

[0047] This production method includes the following steps:

[0048] First, use an electrolytic water device to prepare hydrogen and oxygen; the hydrogen enters the hydrogen storage tank, and the oxygen enters the oxygen storage tank; specifically, calculated based on the production of 1 kg of cement clinker (the same below), the electrolytic water device needs to produce 0.3 - 0.5 Nm 3 of oxygen and 0.7 - 1.0 Nm 3 of hydrogen.

[0049] The oxygen in the oxygen storage tank is introduced into the mixed gas storage tank through a flow meter, and air is introduced into the mixed gas storage tank through a compressor. The oxygen and air are mixed in the mixed gas storage tank to form oxygen-enriched air I, and the oxygen-enriched air I enters the grate cooler for preheating and is discharged from the middle section of the grate cooler to obtain preheated oxygen-enriched air II; specifically, the air intake is 1 - 1.3 Nm 3 .

[0050] The raw material and the tail gas V discharged from the rear section of the grate cooler enter the first preheating separator for heat exchange and gas-solid separation. After the raw material is preheated to a certain temperature, it enters the second preheating separator, and the tail gas VII discharged from the first preheating separator enters the waste heat power generation device; specifically, the mass of the raw material is 1.2 - 1.6 kg, and the amount of the tail gas IV entering the grate cooler is 0.3 - 0.5 Nm 3 .

[0051] It should be noted here that in the initial startup stage, the preheating of the entire system is mainly provided by the combustion of pulverized coal in the rotary kiln. The oxygen required for the combustion of pulverized coal is provided by normal-temperature oxygen-enriched air. The tail gas generated by the rotary kiln can enter the first preheating separator after entering the grate cooler and be heated and mixed with the oxygen-enriched air at the same time. This process can gradually heat the entire system to the temperature for feeding. After feeding, the clinker in the rotary kiln enters the grate cooler, and the system enters the stable operation stage.

[0052] The preheated oxygen-rich air II enters the preheating separator II and exchanges heat with the raw meal therein, preheating the raw meal to a certain temperature, enabling the volatile sulfides, chlorides, and fluorides in the raw meal to volatilize fully and enter the oxygen-rich air, forming preheated raw meal and then entering the catalytic reaction device. A part of the oxygen-rich air III discharged from the preheating separator II serves as oxygen-rich air V and enters the waste heat power generation device, and a part serves as oxygen-rich air IV and enters the rotary kiln; specifically, the volumes of oxygen-rich air IV and oxygen-rich air V are 0.5 - 0.7 Nm 3 and 0.9 - 1.1 Nm 3 .

[0053] The hydrogen in the hydrogen storage tank enters the heat exchange device I and exchanges heat with the mixed gas I in the discharge gas separator to preheat the hydrogen, forming preheated hydrogen I; it should be noted here that at the initial startup, the hydrogen pipeline valve before the heat exchange device I is closed, and hydrogen does not enter the system to participate in the reaction. When the system temperature gradually rises, the hydrogen valve is slowly opened to allow hydrogen to enter the heat exchange device I for heating to ensure the normal operation of the system. Subsequently, preheated hydrogen I enters the hydrogen mixing device and mixes with preheated hydrogen II discharged from the heat exchange device II to obtain preheated hydrogen III at a certain temperature; it should be noted here that at the initial startup, the flow rate of the rotary kiln tail gas is small and the temperature is low, so the heat exchange effect of the heat exchange device II is poor. Since there is no recycled hydrogen for separation and reuse at this time, the hydrogen at the outlet pipeline of the hydrogen storage tank is connected to the heat exchange device II, and there is a hydrogen valve on the pipeline to regulate the gas flow rate. Hydrogen can be circulated and heated in the system until the hydrogen valve entering the heat exchange device II is gradually closed after the rotary kiln is charged. Then, preheated hydrogen III enters the catalytic reaction device; specifically, the volumes of preheated hydrogen I and preheated hydrogen II are 0.8 - 1.0 Nm 3 and 0.2 - 0.4 Nm 3 .

[0054] In the catalytic reaction device, the preheated raw meal and preheated hydrogen III move in the same direction and are fully mixed and reacted, and the material-gas mixture enters the material-gas separator; the pre-calcined raw meal separated by the material-gas separator enters the rotary kiln, and the mixed gas I separated by the material-gas separator enters the heat exchange device I;

[0055] The mixed gas II cooled after leaving the heat exchange device I enters the water removal and purification device, and the mixed gas III after water removal and purification enters the synthesis device. After pressurization and heating, it enters the separation device to separate the target product high-value chemical and the separated and recycled hydrogen. The separated and recycled hydrogen is sent to the heat exchange device II for reuse;

[0056] Pulverized coal enters the burner of the rotary kiln through the coal feeding air and is mixed with the oxygen-enriched air that has been cooled down. The combustion heat causes the raw meal after pre-decomposition to be sintered. After sintering, the clinker enters the grate cooler for cooling, forming the cooled clinker product. The tail gas generated in the rotary kiln enters the heat exchange device II and exchanges heat with the separated and recycled hydrogen in the heat exchange device II. After the tail gas I is preliminarily cooled by heat exchange, it becomes the tail gas II, and the tail gas II enters the waste heat power generation device. The separated and recycled hydrogen in the heat exchange device II is heated up to become the preheated hydrogen II, and the preheated hydrogen II enters the hydrogen mixing device. Specifically, the amount of the separated and recycled hydrogen entering the heat exchange device II is 0.2 - 0.5 Nm 3 , and the amount of the tail gas I entering the heat exchange device II is 0.3 - 1.0 Nm 3 .

[0057] The tail gas III that has been cooled down after exiting the waste heat power generation device enters the dust removal, desulfurization, and denitrification purification device, and then forms the pure tail gas. A part of the pure tail gas is discharged to the outside through the chimney as the tail gas VI, and the other part enters the section of the grate cooler far from the rotary kiln for preliminary preheating as the tail gas IV. After forming the tail gas V at a certain temperature, it enters the preheating separator I for the preliminary preheating of the raw meal. Specifically, the volume of the tail gas III exiting the waste heat power generation device is 1.5 - 2.0 Nm 3 .

[0058] As a preferred embodiment, the volume fraction of oxygen in the oxygen-enriched air I is 28% - 45%, which ensures the efficient combustion of pulverized coal while reducing the total gas volume and heat loss. The temperature of the oxygen-enriched air II is 580 - 600 °C, and the temperature of the tail gas V is 260 - 290 °C.

[0059] As a preferred embodiment, the raw meal is mixed with the reverse water gas shift reaction catalyst. The temperature of the raw meal and catalyst mixture is 60 - 80 °C, and the particle size range is 10 - 100 μm, ensuring that it can be suspended in the reactor. The mass of the catalyst accounts for 5% - 15% of the total mass of the mixture, ensuring the catalytic effect without affecting the quality of the cement clinker.

[0060] As a preferred embodiment, the main components of the catalyst are solid wastes such as steel slag, carbide slag, and manganese slag. It is obtained after reduction at a certain temperature, where the temperature is 450 °C - 650 °C and the reduction time is 0.5 - 2 h, ensuring the full reduction and reconstruction of the active components in the catalyst.

[0061] As a preferred embodiment, the raw meal is preheated by the preheating separator I. The preheating temperature of the raw meal exiting the preheating separator I is 110 - 170 °C. The tail gas V exiting the grate cooler is cooled down after passing through the preheating separator I, and the temperature of the tail gas VII exiting the preheating separator I is 110 - 170 °C.

[0062] As a preferred embodiment, the temperatures of the oxygen-enriched air three exiting the preheating separator two and the preheated raw meal are 390 - 450 °C respectively; the oxygen-enriched air three is a gas containing sulfur and chlorine pollutants. The raw meal preheating temperature is controlled between the decomposition temperature of harmful elements and the carbonate decomposition temperature, ensuring that most of the harmful elements enter the gas and the carbonate hardly decomposes.

[0063] As a preferred embodiment, the temperature of the preheated hydrogen one exiting the heat exchange device one is 550 °C - 590 °C, and the temperature of the preheated hydrogen two exiting the heat exchange device two is 650 - 750 °C.

[0064] As a preferred embodiment, the reaction temperature in the catalytic reaction device is 550 - 750 °C, the raw meal decomposition rate ≥ 95%, and the CO2 conversion rate ≥ 90%; the heating form of the catalytic reaction device is one or a combination of electric heating, microwave heating, and light wave heating.

[0065] As a preferred embodiment, the temperatures of the pre-decomposed raw meal and the mixed gas one exiting the material outlet gas separator are 580 - 700 °C; the main components of the mixed gas one are water vapor, CO, CO2, and H2, where the water vapor concentration ≥ 15%, the ratio of CO to CO2 concentration is 9 - 20, and the ratio of CO to H2 concentration is 0.1 - 0.5; the temperature of the mixed gas two exiting the heat exchange device one is 130 - 170 °C; the water vapor concentration in the mixed gas three after being dewatered and purified by the water removal and purification device ≤ 5%, the ratio of CO to CO2 concentration is 9 - 20, and the ratio of CO to H2 concentration is 0.1 - 0.5.

[0066] As a preferred embodiment, the pressure in the synthesis device is 0.1 MPa - 1.5 MPa, and the reaction temperature is 200 - 350 °C; the high-value chemicals are alkanes, α-olefins, dimethyl carbonate, lower alcohols, etc.

[0067] As a preferred embodiment, the temperature of the tail gas one generated in the rotary kiln is 1050 - 1200 °C, the temperature of the separated and recycled hydrogen entering the heat exchange device two is 30 - 50 °C; the temperature of the tail gas two exiting the heat exchange device two is 380 - 460 °C.

[0068] As a preferred embodiment, the temperature of the tail gas three exiting the waste heat power generation device is 60 - 80 °C; the electric energy generated by the waste heat power generation device goes to the electrolytic water device.

[0069] As a preferred embodiment, the temperature of the cooled clinker exiting the grate cooler is 60 - 90 °C.

[0070] In summary, the present invention can convert and utilize carbon dioxide in carbonates and finally synthesize high-value chemicals, greatly reducing carbon emissions in the cement production process. It can be reformed using existing cement production equipment to maximize the utilization of heat and materials in the cement production system.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-carbon cement production method for co-producing high-value chemicals, characterized in that: It includes the following steps: First, use an electrolytic water device to prepare hydrogen and oxygen; oxygen and air enter a mixed gas storage tank to be mixed to form oxygen-rich air I, and oxygen-rich air I enters a grate cooler for preheating and is discharged from the middle section of the grate cooler to obtain oxygen-rich air II; Raw meal enters a preheater separator I, exchanges heat and performs gas-solid separation with tail gas V discharged from the rear section of the grate cooler. After the raw meal is preheated to a certain temperature, it enters a preheater separator II, and tail gas VII discharged from the preheater separator I enters a waste heat power generation device; Oxygen-rich air II enters the preheater separator II to exchange heat with the raw meal therein, forms preheated raw meal and then enters a catalytic reaction device. Oxygen-rich air III discharged from the preheater separator II is divided into oxygen-rich air IV and oxygen-rich air V. Among them, oxygen-rich air IV enters a rotary kiln, and oxygen-rich air V enters a waste heat power generation device; Hydrogen enters a heat exchange device I, exchanges heat with the mixed gas I of the discharge gas separator to form preheated hydrogen I; preheated hydrogen I enters a hydrogen mixing device, mixes with preheated hydrogen II discharged from a heat exchange device II to obtain preheated hydrogen III at a certain temperature, and then enters a catalytic reaction device; In the catalytic reaction device, the preheated raw meal and preheated hydrogen III move in the same direction, are fully mixed and react. The material-gas mixture enters a material-gas separator; the pre-calcined raw meal after separation enters a rotary kiln, and the mixed gas I enters a heat exchange device I; The mixed gas II discharged from the heat exchange device I enters a water removal and purification device. After being dewatered and purified, the mixed gas III enters a synthesis device. After being pressurized and heated, high-value chemicals and recycled hydrogen are separated. The recycled hydrogen enters a heat exchange device II; Coal powder enters a rotary kiln, mixes with oxygen-rich air IV and burns. The combustion heat is used for firing the pre-calcined raw meal. After firing, the clinker enters a grate cooler for cooling to form a cooled clinker product; tail gas I generated in the rotary kiln enters a heat exchange device II, exchanges heat with the recycled hydrogen, and tail gas I is preliminarily cooled to become tail gas II, and then enters a waste heat power generation device; the recycled hydrogen is heated up to become preheated hydrogen II and enters a hydrogen mixing device; Tail gas III discharged from the waste heat power generation device enters a dust removal, desulfurization and denitration purification device, and then forms pure tail gas; a part of the pure tail gas is discharged through a chimney, and the other part enters a section of the grate cooler far from the rotary kiln for preliminary preheating to form tail gas V and enters a preheater separator I.

2. The low-carbon cement production method for co-producing high-value chemicals according to claim 1, characterized in that, The volume fraction of oxygen in oxygen-rich air I is 28% - 45%; the temperature of oxygen-rich air II is 580 - 600 °C, and the temperature of tail gas V is 260 - 290 °C.

3. The low-carbon cement production method for co-producing high-value chemicals according to claim 1, characterized in that, The raw meal is mixed with a reverse water gas shift reaction catalyst. The temperature of the raw meal and catalyst mixture is 60 - 80 °C, and the particle size range is 10 - 100 μm; the mass of the catalyst accounts for 5% - 15% of the total mass of the mixture; The main components of the catalyst are steel slag, carbide slag, manganese slag and other solid wastes, which are obtained after reduction at a certain temperature, wherein the temperature is 450 °C - 650 °C, and the reduction time is from 0.5 to 2 h.

4. The method for producing low-carbon cement with co-production of high-value chemicals according to claim 1, characterized in that, The preheating temperature of the raw meal discharged from the preheater separator I is 110 - 170 °C, and the temperature of tail gas VII discharged from the preheater separator I is 110 - 170 °C; 5. The low-carbon cement production method for co-producing high-value chemicals according to claim 1, wherein, The temperatures of oxygen-rich air III and preheated raw meal discharged from the preheater separator II are 390 - 450 °C respectively; among them, oxygen-rich air III is a gas containing sulfur and chlorine pollutants.

6. The low-carbon cement production method for co-producing high-value chemicals according to claim 1, characterized in that, The temperature of the preheated hydrogen I exiting the heat exchange device I is 550°C to 590°C, and the temperature of the preheated hydrogen II exiting the heat exchange device II is 650 to 750°C.

7. The low-carbon cement production method for co-producing high-value chemicals according to claim 1, characterized in that, The reaction temperature in the catalytic reaction device is 550 to 750°C, the raw meal decomposition rate ≥ 95%, and the CO2 conversion rate ≥ 90%; the heating form of the catalytic reaction device is a combination of one or several of electric heating, microwave heating, and light wave heating.

8. The method for producing low-carbon cement with co-production of high-value chemicals according to claim 1, characterized in that, The temperature of the pre-decomposed raw meal and the mixed gas I in the outlet gas separator is 580 to 700°C; the main components of the mixed gas I are water vapor, CO, CO2, and H2, where the water vapor concentration ≥ 15%, the ratio of CO to CO2 concentration is 9 to 20, and the ratio of CO to H2 concentration is 0.1 to 0.5; the temperature of the mixed gas II is 130 to 170°C; the water vapor concentration in the mixed gas III ≤ 5%, the ratio of CO to CO2 concentration is 9 to 20, and the ratio of CO to H2 concentration is 0.1 to 0.

5.

9. The method for producing low-carbon cement with co-production of high-value chemicals according to claim 1, characterized in that, The pressure in the synthesis device is 0.1 MPa to 1.5 MPa, and the reaction temperature is 200 to 350°C; the high-value chemicals are alkanes, α-olefins, dimethyl carbonate, and lower alcohols.

10. The low-carbon cement production method for co-producing high-value chemicals according to claim 1, wherein, The temperature of the tail gas I is 1050 to 1200°C, and the temperature of the separated and recycled hydrogen is 30 to 50°C; the temperature of the tail gas II is 380 to 460°C.

11. The method for producing low-carbon cement with co-production of high-value chemicals according to claim 1, characterized in that, The temperature of the tail gas III exiting the waste heat power generation device is 60 to 80°C; the electric energy generated by the waste heat power generation device goes to the electrolytic water device.

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