A carbon-negative cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution

Abstract

This invention pertains to the field of negative carbon cement production and discloses a negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution. The system includes a solid waste-based adsorbent preparation module, a cement production module, and a calcium recycling carbon capture module. The calcium recycling carbon capture module has its reactor inlet connected to the outlet of the solid waste-based adsorbent preparation module, and its reactor inlet connected to the exhaust outlet of the rotary kiln unit. Furthermore, the calcium recycling carbon capture module is connected to the batching silo of the cement raw material batching unit via its discharge port. By integrating these modules, this invention constructs a closed-loop recycling system centered on the recycling of multi-source solid waste calcium-based CO2 adsorbents and the resource-based reuse of deactivated calcium-based adsorbents, encompassing "adsorbent preparation – carbon capture – adsorbent regeneration – deactivated calcium-based adsorbent substitution for cement raw materials," significantly reducing carbon emissions throughout the entire lifecycle of negative carbon cement production.

Description

Technical Field

[0001] This utility model belongs to the field of negative carbon cement production technology, and more specifically, relates to a negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution. Background Technology

[0002] The cement industry is a key source of global carbon emissions, accounting for approximately 5% of total global CO2 emissions. As a major cement producer and consumer, my country's annual CO2 emissions exceed 700 million tons, facing immense pressure to reduce emissions. In accordance with the Paris Agreement's goal of net-zero emissions by 2050, the cement industry urgently needs to significantly increase its emission reduction efforts. However, currently, CO2 emissions per ton of cement clinker are still as high as approximately 860 kg, far exceeding the low-carbon target (520 kg / t). Although existing technologies such as solid waste feedstock substitution, fuel substitution, and CCUS (carbon capture, storage, and utilization) have been applied, they still generally face bottlenecks such as high costs, insufficient carbon reduction depth, and poor system continuity.

[0003] Among existing emission reduction pathways, solid waste substitution technology mainly refers to partially replacing traditional limestone raw materials with industrial waste such as carbide slag, steel slag, and fly ash. This reduces process emissions by decreasing CO2 generated during carbonate decomposition. This type of technology utilizes the existing calcium content in solid waste to avoid partial limestone calcination, achieving direct emission reduction in a single production run. On the other hand, CCUS technology focuses on capturing and storing CO2 in kiln tail gas. Calcium cycling (Ca-Looping) technology uses calcium oxide-based adsorbents to capture CO2 during the carbonization-calcination cycle, while amine absorption technology relies on organic amine solutions for chemical adsorption of CO2. Both can significantly reduce direct emissions during cement production.

[0004] While solid waste substitution and CCUS technology each have certain emission reduction effects, they are still partial decarbonization methods, and their overall life-cycle carbon emission levels remain high, making it impossible to achieve carbon-negative cement production. Solid waste substitution only achieves emission reduction in the single raw material stage and does not establish a mechanism for multiple CO2 captures through adsorbent cycles, thus limiting its overall carbon reduction potential. CCUS technology, especially the amine method, suffers from high regeneration energy consumption and solvent degradation issues. Calcium-based adsorbents also deactivate after multiple cycles, and traditional disposal methods often discard them, failing to utilize their residual calcium source value and causing secondary solid waste emissions, resulting in a still high overall system carbon footprint. Therefore, the existing technological architecture suffers from process fragmentation, lack of material closure, and a lack of multi-cycle carbon recycling mechanisms, making it difficult to achieve deep decarbonization and unable to support the production target of carbon-negative cement. Utility Model Content

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this utility model provides a negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution. Its purpose is to integrate a solid waste-based adsorbent preparation module, a cement production module, and a calcium recycling carbon capture module to construct a closed-loop recycling system centered on the recycling of multi-source solid waste calcium-based CO2 adsorbents and the resource-based reuse of deactivated calcium-based adsorbents. This system comprises "adsorbent preparation - carbon capture - adsorbent regeneration - deactivated calcium-based adsorbent substitution for cement raw materials," thereby solving the technical challenges of carbon emissions throughout the entire lifecycle of negative carbon cement production.

[0006] To achieve the above objectives, in one aspect of this utility model, a negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution is provided, including a solid waste-based adsorbent preparation module, a cement production module, and a calcium recycling carbon capture module. The cement production module includes a cement raw material batching unit, a cement raw material grinding module, a clinker calcination module, and a cement grinding module connected in sequence; the clinker calcination module includes a rotary kiln unit. The calcium circulating carbon capture module has its reactor feed port connected to the discharge port of the solid waste-based adsorbent preparation module, and its reactor air inlet connected to the exhaust port of the rotary kiln unit; and the calcium circulating carbon capture module is connected to the batching silo of the cement raw material batching unit through its discharge port.

[0007] Preferably, the reactor of the calcium circulating carbon capture module is in the form of a circulating fluidized bed, a fixed bed, or a moving bed device.

[0008] Preferably, the reactor of the calcium circulating carbon capture module is in the form of a circulating fluidized bed device, comprising a carbonation reactor and a regeneration reactor; the feeding port of the carbonation reactor is connected to the discharge port of the solid waste-based adsorbent preparation module, and its air inlet is connected to the exhaust outlet of the rotary kiln unit; and the carbonation reactor and the regeneration reactor are connected by a conveying pipeline to form a circulation path, and the regeneration reactor is connected to the batching silo of the cement raw material batching unit through a discharge port.

[0009] Preferably, a heat exchanger is also provided between the rotary kiln unit and the calcium circulating carbon capture module.

[0010] Preferably, the tail gas outlet of the carbonation reactor is also equipped with a CO2 sensor.

[0011] Preferably, control valves are provided at the discharge port of the solid waste-based adsorbent preparation module, the exhaust port of the rotary kiln unit, and the unloading port of the calcium circulating carbon capture module.

[0012] Preferably, a calcium-based adsorbent storage chamber is provided between the calcium recycling carbon capture module and the cement raw material batching unit.

[0013] Preferably, the clinker calcination module further includes a humidification tower unit, which is connected to the grinding unit in the cement raw material grinding module.

[0014] In summary, compared with the prior art, the above-described technical solution conceived by this utility model has the following main technical advantages: 1. This utility model integrates a solid waste-based adsorbent preparation module, a cement production module, and a calcium recycling carbon capture module. The calcium recycling carbon capture module is connected to the discharge port of the solid waste-based adsorbent preparation module and to the exhaust port of the rotary kiln unit. Simultaneously, the calcium recycling carbon capture module is connected to the cement raw material batching unit through the discharge port. This constructs a closed-loop recycling system with the recycling capture of multi-source solid waste calcium-based CO2 adsorbents and the resource-based reuse of deactivated calcium-based adsorbents as its core, consisting of "adsorbent preparation—carbon capture—adsorbent regeneration—deactivated calcium-based adsorbent replacement of cement raw materials." Through the high synergy between material flow and carbon flow, it can not only significantly reduce the carbon emissions of cement throughout its entire life cycle and promote the overall process of negative carbonization, but also realize the resource utilization of deactivated calcium-based adsorbents as alternative raw materials, avoiding secondary pollution of solid waste, which is in line with the principles of circular economy. Furthermore, the carbon capture unit is highly integrated into the main cement production process, improving carbon capture efficiency while ensuring the coordination and operational stability of the production system.

[0015] 2. The reactor in the calcium cycle carbon capture module of this utility model is preferably in the form of a dual fluidized bed device, which includes a carbonation reactor and a regeneration reactor. The carbonation and calcination processes are completed by means of two reactions, respectively, to achieve the efficient operation of the closed-loop circulation system, thereby improving the carbon capture efficiency.

[0016] 3. Preferably, a heat exchanger is provided between the rotary kiln unit and the calcium circulating carbon capture module in this utility model. The waste heat of the rotary kiln tail exhaust gas is transferred to the calcium circulating carbon capture module through the heat exchanger as a heat source for absorption / desorption regeneration, thereby reducing the energy consumption of the system operation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the composition and structure of the negative carbon cement production system based on the cyclic capture of multi-source solid waste calcium-based CO2 adsorbent and the replacement of cement raw materials with deactivated calcium-based adsorbent. Figure 2 This is a schematic diagram of the composition and structure of the negative carbon cement production system in Embodiment 2 of this utility model.

[0018] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Cement raw material batching unit, 2-Cement raw material grinding module, 3-Solid waste-based adsorbent preparation module, 4-Clinker calcination module, 5-Calcium circulating carbon capture module, 6-Cement grinding module. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model. Furthermore, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0020] To address the aforementioned issues, this invention proposes a carbon-negative cement production system. Based on traditional cement production processes, this system integrates a calcium-based adsorbent carbon dioxide recycling and capture unit prepared from multi-source solid waste. This unit treats carbon dioxide emissions from cement rotary kilns and reuses the deactivated adsorbent as a substitute raw material in cement production, achieving a high degree of synergy between carbon capture and the cement production system.

[0021] This invention provides a negative carbon cement production system based on the cyclic capture of multi-source solid waste calcium-based CO2 adsorbents and the replacement of cement raw materials with deactivated calcium-based adsorbents. For example... Figure 1 As shown, the system includes a solid waste-based adsorbent preparation module 3, a cement production module, and a calcium circulating carbon capture module 5. The cement production module includes a cement raw material batching unit 1, a cement raw material grinding module 2, a clinker calcination module 4, and a cement grinding module 6 connected in sequence. The clinker calcination module includes a rotary kiln unit. A calcium circulating carbon capture module is introduced, with its feed port connected to the discharge port of the solid waste-based adsorbent preparation module and its air inlet connected to the exhaust port of the rotary kiln unit. The calcium circulating carbon capture module is connected to the batching bin of the cement raw material batching unit through a discharge port.

[0022] Therefore, the system first uses a solid waste-based adsorbent preparation module to co-prepare calcium-based CO2 adsorbent from multiple solid waste sources. The prepared calcium-based CO2 adsorbent is then introduced into a calcium-based circulating carbon capture module, where it is used for subsequent circulating capture of CO2 from cement kiln exhaust gas. Additionally, carbon-containing gas generated by the rotary kiln unit of the clinker calcination module is introduced into the calcium-based circulating carbon capture module through the exhaust outlet of the rotary kiln unit. This carbon-containing gas participates in the subsequent carbonization reaction process within the calcium-based circulating carbon capture module. Then, the calcium-based CO2 adsorbent from the solid waste-based adsorbent preparation module is circulated with the carbon-containing gas from the rotary kiln unit through the calcium-based circulating carbon capture module to undergo a carbonization / calcination reaction until a deactivated calcium-based adsorbent is formed. Finally, the calcium-based circulating carbon capture module is connected to a cement raw material batching unit, allowing the deactivated calcium-based adsorbent to be reused as a substitute raw material in cement raw material batching. This closed-loop process, through a closed-loop cycle system of "adsorbent preparation - carbon capture - adsorbent regeneration - deactivated calcium-based adsorbent replacement of cement raw materials," achieves a high degree of synergy between material flow and carbon flow. This not only significantly reduces carbon emissions throughout the entire life cycle of cement and promotes the overall process towards negative carbonization, but also enables the resource utilization of deactivated calcium-based adsorbents as alternative raw materials, avoiding secondary pollution from solid waste. Furthermore, it highly integrates the carbon capture unit into the main cement production process, improving carbon capture efficiency while ensuring the coordination and operational stability of the production system.

[0023] Multi-source solid waste specifically refers to industrial solid wastes rich in calcium. These originate from various industrial production processes, and include typical solid wastes with high calcium content such as carbide slag, white mud, fly ash, and steel slag.

[0024] In this invention, the solid waste-based adsorbent preparation module includes an adsorbent powder preparation and modification module, an adsorbent forming module, and an adsorbent calcination module connected in sequence. Specifically: The adsorbent powder batching and modification module includes a mixer and a physicochemical co-activation unit (e.g., a dry ball mill, an alkali metal salt low-temperature thermal activation module), which is used to use industrial solid wastes such as carbide slag, steel slag, and fly ash as raw materials, and to meter and mix them according to a preset ratio by a mixer (e.g., a jaw crusher).

[0025] The adsorbent forming module includes a roller briquetting machine and a cutting machine, which are used to feed the mixture into the roller briquetting machine via a belt conveyor to form an adsorbent precursor with a certain mechanical strength.

[0026] The adsorbent calcination module includes an activation furnace, which is used to activate and calcine the adsorbent at 800-900℃ using a rotary activation furnace, ultimately obtaining a granular calcium-based CO2 adsorbent with high CO2 adsorption activity and good wear resistance.

[0027] In this utility model, the cement production module includes a cement raw meal batching unit, a cement raw meal grinding module, a clinker calcination module, and a cement grinding module connected in sequence, specifically: In the raw material batching unit of cement, during the raw material batching stage, the system uses a quantitative feeder to add a certain proportion of deactivated calcium-based adsorbent into the raw materials, which are then fed into the raw material silo along with conventional raw materials such as limestone, clay, and iron powder. The quantitative feeding system and electronic belt scale are used to achieve precise batching.

[0028] The cement raw meal grinding module uses a vertical mill or a ball mill for combined grinding. The residue of the raw meal on an 80μm square hole sieve after grinding is controlled to be less than 12%. The raw meal is then transported to a homogenization silo via an air chute and a bucket elevator for continuous homogenization, forming modified raw meal with uniform chemical composition.

[0029] The clinker calcination module transports modified raw meal to the rotary kiln system for calcination. Specifically, the clinker calcination module includes a rotary kiln, a cooler, and a clinker silo. In a high-temperature environment, the modified raw meal undergoes mineral phase deformation to produce clinker, while simultaneously generating kiln tail gas (i.e., carbon-containing gas) with a high concentration of CO2.

[0030] The cement grinding module is used to co-grind the cement clinker produced by the clinker calcination module with an appropriate amount of gypsum and admixtures (such as fly ash and slag). Specifically, this module uses grinding equipment such as ball mills or roller presses for final grinding, strictly controlling the specific surface area and particle size distribution of the finished cement product to ensure it meets the strength grade requirements.

[0031] In this invention, the system also integrates a calcium circulation carbon capture module, which is deeply coupled with the rotary kiln system.

[0032] Specifically, the reactor for the calcium circulating carbon capture module can also adopt one or more combinations of circulating fluidized bed, fixed bed, moving bed, and rotary bed devices to achieve thermal parameter matching and material transfer coupling with the rotary kiln system. A dual fluidized bed system uses two connected fluidized beds for carbonation capture and calcination regeneration respectively, with circulating adsorbent transported through pipelines to improve carbon capture efficiency and is more suitable for large-scale continuous production. A fixed bed or moving bed series system achieves adsorption and regeneration operations through multiple reactor combinations and valve switching, offering operational flexibility and adaptability to small- to medium-scale operations or fluctuating gas volumes. A rotary reactor adopts a rotary kiln structure, where the adsorbent undergoes reactions in different temperature zones within the rotating cylinder, featuring a compact structure suitable for space-constrained retrofit projects. The preferred circulating fluidized bed or moving bed process of this invention has significant advantages in system integration, compatibility with cement kiln thermal regimes, heat and mass transfer efficiency, and stability during large-scale operation, especially facilitating deep coupling with the main cement production system at the material and energy levels.

[0033] Preferably, the calcium circulating carbon capture module includes a carbonation reactor and a regeneration reactor, which are connected in a circular flow path through a conveying pipeline. The carbonation reactor is connected to the discharge port of the solid waste-based adsorbent preparation module and to the exhaust port of the rotary kiln unit through a high-temperature resistant sealed pipeline. It is used to carry out a circulating carbonation / calcination reaction between the calcium-based CO2 adsorbent from the solid waste-based adsorbent preparation module and the carbon-containing gas from the rotary kiln unit through the carbonation reactor and the regeneration reactor until a deactivated calcium-based adsorbent is formed. The carbonation reactor is connected to the regeneration reactor through a discharge port, and the regeneration reactor is connected to the cement raw material batching unit through a discharge port. It is used to transfer the deactivated calcium-based adsorbent to the cement raw material batching unit to replace part of the cement raw material.

[0034] Preferably, the tail gas outlet of the carbonation reactor is also equipped with a CO2 sensor, which is connected to the control module. When the CO2 sensor is not used, the operation of the calcium cycle carbon capture module can be preset. When the CO2 sensor is introduced, the control module obtains the CO2 concentration information in the reactor of the calcium cycle carbon capture module to coordinate with other modules to precisely control the cement production process.

[0035] Preferably, a heat exchanger is also provided between the rotary kiln unit and the calcium circulating carbon capture module to introduce the waste heat of the rotary kiln tail exhaust gas as a heat source for absorption / desorption regeneration.

[0036] Inside the carbonation reactor, the high-carbon waste gas comes into full contact with the calcium-based adsorbent in the carbonation reactor or the calcium-based adsorbent returned from the regeneration reactor. The adsorbent reacts with CO2 through chemical adsorption to generate calcium carbonate, thus achieving efficient capture of CO2 from the high-carbon waste gas.

[0037] Specifically: A CO2 sensor detects that the CO2 concentration in the carbonation reactor exceeds 15-20%, indicating adsorption saturation. The calcium-based adsorbent is then fed into the regeneration reactor via a discharge valve and conveying pipeline at the bottom of the reactor. The regeneration reactor operates at a temperature controlled between 900 and 1000 degrees Celsius. Waste heat from the rotary kiln tail gas is introduced via a heat exchanger as the heat source for adsorption / desorption regeneration. The calcium-based adsorbent is calcined and decomposed at high temperature, releasing high-purity CO2 (the decomposition reaction of calcium carbonate). This high-purity CO2 is then transported via a gas collection pipeline to a CO2 storage tank or a subsequent utilization system. The regenerated adsorbent is returned to the carbonation reactor to continue participating in the capture process (the carbonation reaction of calcium oxide), forming a circular loop. This process utilizes the waste heat from the cement kiln exhaust gas and the high-temperature environment of the system, significantly reducing regeneration energy consumption and improving system energy efficiency.

[0038] As the number of cycles increases, once the CO2 concentration in the carbonation reactor reaches a preset value as detected by the CO2 sensor, it is determined that the adsorbent has gradually become deactivated due to sintering, wear, and other reasons. The system then sends the deactivated calcium-based adsorbent to the raw material silo of the cement production unit in the cement raw material batching unit through a dedicated discharge valve and conveying pipeline at the bottom of the regeneration reactor, where it is reused as a calcium substitute. The main components of the deactivated calcium-based adsorbent are calcium oxide and a small amount of inert substances. It can partially replace limestone in the raw materials, directly reducing emissions during the carbonate decomposition process, while simultaneously achieving full-scale and high-value utilization of industrial solid waste.

[0039] Preferably, the clinker calcination module also includes a humidification tower, which is connected to the grinding unit in the cement raw meal grinding module, to increase the humidity of dust during raw meal grinding, thereby achieving purification treatment of the raw meal. In this invention, a negative carbon cement production system based on the cyclic capture of multi-source solid waste calcium-based CO2 adsorbent and the replacement of cement raw materials with deactivated calcium-based adsorbent is provided. The system includes a control module for coordinating the above modules to regulate carbon emissions in the cement production process, thereby achieving system-level carbon balance or even negative carbon emissions.

[0040] Preferably, the discharge port of the solid waste-based adsorbent preparation module, the exhaust port of the rotary kiln unit, and the unloading port of the calcium circulating carbon capture module are all equipped with control valves. The control valves are all connected to the control module so as to coordinate and regulate each link of the cement production process through the central control system.

[0041] Preferably, a calcium-based adsorbent storage chamber is also provided between the calcium cycle carbon capture module and the cement raw material batching unit for temporarily storing deactivated calcium-based adsorbent from the calcium cycle carbon capture module. Furthermore, the calcium-based adsorbent storage chamber is connected to the intelligent control module or the quantitative proportioning module of the cement raw material batching unit to achieve precise replacement of the cement raw material with the deactivated calcium-based adsorbent.

[0042] Preferably, the control module includes a carbon emission quantification module and a raw material batching control module. The carbon emission quantification module is used to obtain the CO2 emission equivalent generated by each module (wherein, the CO2 emission equivalent generated by each module is calculated based on the energy consumption of each module, but the clinker calcination module obtains it through CO2 concentration detection; for example, the CO2 emission equivalent generated by each module is calculated based on the energy consumption of each module. If the module uses a kWh of electricity, it will generate b CO2 emission equivalents). The total CO2 emission equivalent of the entire cement production process is obtained by summing the CO2 emission equivalents. Then, the replacement ratio of deactivated calcium-based adsorbent is calculated based on the total CO2 emission equivalents and fed back to the raw material batching control module. The raw material batching control module is used to transport the deactivated calcium-based adsorbent to the batching bin of the cement raw material batching unit and use it to replace the raw materials of cement production according to the replacement ratio of the deactivated calcium-based adsorbent for proportioned reuse. Specifically, to determine the substitution ratio of deactivated calcium-based adsorbents in raw materials, the carbon emissions of the entire cement production lifecycle, including raw material mining, transportation, adsorbent preparation, cement production, CO2 capture, product utilization, and waste disposal, are quantified. This yields the CO2 emission equivalent for the entire cement production process. Then, based on this total emission equivalent and the total carbon capture capacity of the adsorbent, the substitution ratio of deactivated calcium-based adsorbents is calculated and fed back to the raw material batching control unit. For example, assuming the total emission equivalent is X tons of CO2, and each ton of adsorbent can capture a cumulative amount of Y tons of CO2 before deactivation, the substitution ratio of deactivated calcium-based adsorbents is X / Y. The quantification of carbon emissions for each module is performed using OpenLCA, Simapro, and Gabi software.

[0043] Preferably, the control module further includes a raw material batching optimization module, used to compare the replacement ratio of deactivated calcium-based adsorbent with a preset ratio. If the replacement ratio of deactivated calcium-based adsorbent is less than the preset ratio, the replacement ratio of deactivated calcium-based adsorbent is adjusted to the preset ratio. The preset ratio is the ratio of the total CO2 emission equivalent during the production of negative carbon cement to the total carbon capture capacity of the adsorbent. The preset ratio is equal to X / Y. When the preset ratio is equal to the replacement ratio, the system has zero carbon emissions. When the preset ratio is greater than the replacement ratio, the system has negative carbon emissions.

[0044] Alternatively, a preferred approach involves combining techno-economic analysis to assess the combined impact of different substitution ratios on the incremental costs of cement production raw materials, energy consumption, and operator depreciation, as well as the revenue from solid waste disposal and carbon trading. This multi-objective optimization aims to maximize carbon reduction benefits and ultimately achieve system-level carbon balance or even negative carbon production. Specifically, the control module may also include a raw material batching optimization module to adjust the substitution ratio of deactivated calcium-based adsorbent to a preset ratio. This preset ratio is the ratio of the total CO2 emission equivalent to the total carbon capture capacity of the adsorbent. The total carbon capture capacity of the adsorbent is the sum of the cost increment and solid waste disposal revenue per unit of adsorbent carbon capture capacity, subtracted from the carbon trading revenue. The value obtained when the result is zero is used.

[0045] The above-mentioned application of the negative carbon cement production system based on the cyclic capture of multi-source solid waste calcium-based CO2 adsorbents and the replacement of cement raw materials with deactivated calcium-based adsorbents includes the following steps: (1) Prepare calcium-based CO2 adsorbent from multi-source solid waste through the solid waste-based adsorbent preparation module, and then introduce the calcium-based CO2 adsorbent into the calcium cycle carbon capture module; and produce cement through the cement production module, and introduce the carbon-containing gas generated through the rotary kiln unit of the clinker calcination module into the calcium cycle carbon capture module through the tail gas outlet of the rotary kiln unit. (2) The calcium-based CO2 adsorbent is subjected to a cyclic carbonation / calcination reaction with carbon-containing gas through a calcium-cycle carbon capture module until a deactivated calcium-based adsorbent is formed; (3) Then, the deactivated calcium-based adsorbent is transported to the cement raw material batching unit through the control module to replace the raw materials for cement production and reuse them in proportion, thus completing the closed-loop cycle of cement production.

[0046] Preferably, the proportion of multi-source solid waste is consistent with the proportion of raw materials in cement production. By utilizing the consistency of components, the deactivated adsorbent is used as a "standardized substitute material", which simplifies the batching calculation, stabilizes the chemical composition of raw materials, and improves the reliability and efficiency of the entire co-processing process.

[0047] Preferably, in step (3), the deactivated calcium-based adsorbent is then transported to the cement raw material batching unit by the control module to replace the raw materials for cement production and reused in proportion. Specifically, the CO2 emission equivalent generated by each module is obtained by the control unit, and the CO2 emission equivalent of the entire cement production process is obtained. The replacement ratio of the deactivated calcium-based adsorbent is calculated based on this total emission equivalent, and then the deactivated calcium-based adsorbent is replaced with the raw materials for cement production in proportion according to the amount of the deactivated calcium-based adsorbent replacement ratio and reused in proportion.

[0048] Furthermore, the replacement ratio of deactivated calcium-based adsorbent is also adjusted according to a preset ratio; when the preset ratio is customizable, the preset ratio is greater than or equal to the replacement ratio of deactivated calcium-based adsorbent, or the preset ratio is determined by subtracting the carbon trading revenue from the sum of the cost increment brought by the total carbon capture capacity per unit of adsorbent and the solid waste disposal revenue, and taking the positive value.

[0049] The present invention will now be described in further detail with reference to the accompanying drawings.

[0050] Example 1: A carbon-negative cement production system includes: a cement raw meal batching unit 1, a solid waste-based adsorbent preparation module 3, a cement raw meal grinding module 2, a clinker calcination module 4, a cement grinding module 6, and a calcium recycling carbon capture module 5. Specifically: The solid waste-based adsorbent preparation module 3 includes a batching silo, a mixer, a molding device, and an activation furnace. The outlet of the batching silo is connected to the inlet of the mixer, the outlet of the mixer is connected to the inlet of the molding device, and the outlet of the molding device is connected to the inlet of the activation furnace. The molding device is a double-roll briquetting machine, and the activation furnace is a rotary activation furnace.

[0051] The cement raw material batching unit 1 pre-processes raw materials such as limestone, clay, and sandstone, including crushing equipment, screening equipment, a pre-homogenization stockpile, and batching bins connected in sequence. The crushing equipment is a jaw crusher, the screening equipment is a vibrating screen, the pre-homogenization stockpile is equipped with a stacker-reclaimer, and the batching bins are equipped with a quantitative feeder.

[0052] Cement raw meal grinding unit 2 includes grinding equipment, a raw meal homogenization silo, and a feeding and metering unit. The discharge port of the metering feeder is connected to the inlet of the grinding equipment, and the discharge port of the grinding equipment is connected to the inlet of the homogenization silo. The grinding equipment is a vertical mill.

[0053] The clinker calcination module 4 includes a rotary kiln, a cooler, and a clinker silo.

[0054] The cement grinding module 6 includes a cement mill and a finished product silo.

[0055] The calcium circulating carbon capture module 5 includes a dual-circulation fluidized bed reactor and conveying pipelines. The dual-circulation fluidized bed reactor comprises a carbonation reactor and a regeneration reactor. The outlet of the carbonation reactor is connected to the regeneration reactor via a first conveying pipeline, and the outlet of the regeneration reactor is connected to the inlet of the carbonation reactor via a second conveying pipeline, forming a circulation path for the dual-circulation fluidized bed reactor. The inlet of the carbonation reactor is connected to the exhaust gas outlet of the rotary kiln via a high-temperature resistant pipeline, and the discharge port of the deactivated calcium-based adsorbent in the regeneration reactor is connected to the feed port of the quantitative feeder in the cement raw material batching unit 1.

[0056] The applications of this system specifically include: In module 3 of the solid waste-based adsorbent preparation, carbide slag (mainly composed of Ca(OH)2 and CaCO3, with a CaO mass fraction ≥91% and no loss on ignition) and high-calcium fly ash (CaO mass fraction approximately 22.7%) are used as the main raw materials, and are proportioned at a CaO to Al2O3+SiO2 mass ratio of 75:25. To improve the cycle stability and mechanical strength of the adsorbent, a small amount of high-alumina cement with Al2O3 contents of 50% and 80% is added to the proportion, adjusting the mass fractions of CaO, SiO2, and Al2O3 in the final system to 75%, 12.5%, and 12.5%, respectively. After the raw materials are transported to the plant's storage yard, they are initially crushed by a jaw crusher using a loader according to the proportion, controlling the particle size of the crushed material to be no greater than 5mm. The crushed material is then conveyed to the batching silo by a bucket elevator, which is equipped with a quantitative feeder and belt scale to achieve precise metering and proportion control of the material. The material is then conveyed by a belt conveyor to a mixer, and then pre-treated in a dry ball mill to increase its specific surface area and reactivity. The ball-milled powder is then fed into a roller briquetting mill, where it is shaped into wet strips of specified specifications (60-150 μm in diameter). After drying at 75℃ for 12 hours, it is cut into cylindrical particles approximately 100 μm in length. The shaped particles are then conveyed to a rotary activation furnace and calcined at 850℃ for 1 hour to complete the activation process, yielding granular calcium-based adsorbents with high mechanical strength (compressive strength ≥70N) and excellent CO2 cyclic adsorption performance. The activated calcium-based adsorbents are cooled and then transferred to a calcium-based adsorbent storage silo for later use.

[0057] The cement raw meal batching unit 1 is basically the same as the current cement production system's processing system, mainly consisting of crushing equipment, screening equipment, a pre-homogenization stockpile, and batching bins connected in sequence. The crushing equipment preferably uses a jaw crusher for preliminary crushing of raw materials such as limestone, clay, and sandstone, controlling the output particle size to be no greater than 50mm. The screening equipment uses a vibrating screen to remove oversized particles and impurities, ensuring that the feed particle size for subsequent processes does not exceed 25mm. The pre-homogenization stockpile is equipped with a stacker-reclaimer, which uses a "flat-laying direct-reclaiming" operation mode to pre-homogenize the screened qualified materials, achieving preliminary homogenization and stabilization of the material's chemical composition. The pre-treated material is then transported by belt conveyor to the subsequent batching bin for raw meal preparation.

[0058] In the batching silo, the calcium-based adsorbent, discharged from the calcium circulating carbon capture module 5 and completely deactivated after approximately 20 carbonation-regeneration cycles (with an adsorption capacity less than 20% of the initial value), whose main components are CaO and inert substances, is quantitatively transported to the batching silo via a dedicated conveying pipeline. A quantitative feeder precisely batches the deactivated calcium-based adsorbent, limestone, clay, sandstone, and iron powder, among other conventional raw materials, according to this ratio. The batch is fed into a vertical mill for co-grinding, controlling the grinding fineness to ensure that the residue on an 80μm square-hole sieve is less than 12%. The ground raw material is then conveyed via an air chute and bucket elevator to a homogenization silo for continuous homogenization, ultimately obtaining a modified raw material with a uniform and stable chemical composition (fluctuations in key components such as CaO, SiO2, Al2O3, and Fe2O3 less than ±0.5%).

[0059] In clinker calcination module 4, the homogenized modified raw meal is continuously and stably fed into a five-stage cyclone preheater system via a closed belt conveyor system. Within this system, the raw meal undergoes counter-current heat exchange with the high-temperature hot airflow from the rotary kiln, passing sequentially through preheating units C5 to C1. The material temperature gradually increases to 800-900℃, and some carbonate decomposition occurs. Subsequently, the material enters the decomposition furnace, where, at approximately 880℃ and in an oxygen-rich environment, most of the carbonates (approximately 90%-95%) rapidly decompose to generate calcium oxide and CO2. The decomposed material then enters the rotary kiln, where solid-phase reaction and liquid-phase sintering occur at approximately 1450℃, ultimately forming cement clinker with calcium silicate as the main mineral. The high-temperature kiln tail gas generated during this calcination process (temperature approximately 300-350℃, CO2 volume concentration 20%-30%, and also containing small amounts of SO2 and NO)... x The components (such as CO2, CO2, CO2, CO2, CO2) are discharged from the outlet of the final preheater and transported to the integrated adsorption-desorption unit at the back end through a specially designed high-temperature and corrosion-resistant sealed pipeline system to achieve efficient CO2 capture and adsorbent recycling.

[0060] The calcium-cycle carbon capture module 5, as the core component for CO2 capture and adsorbent recycling, is deeply coupled with the cement rotary kiln system. This embodiment employs a dual-circulating fluidized bed reactor system, mainly comprising a carbonation reactor and a regeneration reactor. Kiln tail gas is conveyed to the bottom of the carbonation reactor, where the operating temperature is controlled between 650℃ and 700℃. Simultaneously, highly active adsorbent from the regeneration reactor is continuously fed into the carbonation reactor via a conveying system. Inside the reactor, the adsorbent particles fully fluidize and countercurrently contact the kiln tail gas, undergoing a carbonation reaction: CaO + CO2 → CaCO3, thereby efficiently capturing CO2 from the exhaust gas. The purified flue gas, after capture, is discharged from the top of the reactor, with its CO2 concentration reduced to below 1%. This purified flue gas is then treated by subsequent dust removal, desulfurization, and denitrification processes to meet emission standards. Pilot-scale operation data shows that, under a CO2 flow rate of 150 kg / h, the CO2 concentration at the system outlet is below 1% for the first 2 hours, with a CO2 capture rate approaching 100%; after 4 hours of operation, the capture rate still remains at 92.82%. Based on the comprehensive experimental results, controlling the carbonation reaction time to 2-3 hours ensures continuous and efficient CO2 removal, with a capture rate consistently above 98%. The calcium carbonate formed after adsorption saturation accumulates at the bottom of the carbonation reactor and is fed into the regeneration reactor via a high-temperature pneumatic conveying pipeline through a high-temperature discharge valve and corresponding control system. The operating temperature of the regeneration reactor is strictly controlled between 900°C and 1000°C. The required heat is mainly provided by the high-temperature waste gas introduced into the rotary kiln system through a waste heat utilization pipeline, serving as the main heat source for the regeneration reaction and significantly reducing the system's regeneration energy consumption. Under high-temperature conditions, the adsorbent undergoes a calcination decomposition reaction CaCO3 → CaO + CO2, releasing high-purity CO2 gas (concentration not less than 95%). After being discharged from the top of the regeneration reactor, the gas enters the CO2 purification and resource utilization unit, where it can be compressed, liquefied, stored, or used in chemical processes. The regenerated and activated adsorbent is returned to the carbonation reactor via a discharge and conveying system at the bottom of the regeneration reactor, re-participating in the CO2 capture process and forming an adsorbent recycling loop. After approximately 15 to 20 carbonation-regeneration cycles, the cumulative adsorption capacity reaches 4.47 g CO2 / g adsorbent, after which its activity significantly declines, typically falling below 20% of the initial adsorption capacity, at which point it is considered deactivated. When the adsorbent has been recycled approximately 20 times, its adsorption capacity declines to a critical point (below 0.20 g CO2 / g adsorbent). The system quantitatively discharges this deactivated calcium-based adsorbent through a dedicated discharge valve at the bottom of the regeneration reactor. This deactivated adsorbent is then conveyed via pneumatic pipeline to the raw material silo of the raw material preparation and homogenization unit, where it replaces part of the limestone as a calcium-based raw material, re-entering the raw material preparation cycle, ultimately achieving full-scale and high-value utilization of industrial solid waste within the system.

[0061] Cement grinding module 6 includes a cement mill and a finished product silo. Cement clinker discharged from the grate cooler of the clinker calcination subsystem is conveyed into the clinker inlet of the cement mill. Simultaneously, a predetermined amount of gypsum and admixtures are added to the cement mill according to a preset ratio via quantitative feeding devices below their respective batching silos. The cement mill is preferably a ball mill or a vertical mill, which jointly grinds the clinker, gypsum, and admixtures. By adjusting the grinding process parameters, the specific surface area of ​​the finished cement is controlled to be around 350 m². 2 / kg to 400m 2 The cement concentration is between [value] kg / kg, and the residue on an 80μm square-hole sieve is no more than 4%. The ground cement is then conveyed to a cement silo for storage. The silo is equipped with a packaging machine or bulk shipping system for the final shipment of the cement products.

[0062] The proportion of deactivated calcium-based adsorbent replacing raw materials can be dynamically adjusted according to the system's required carbon emission reduction target. This embodiment aims to achieve a 90% reduction in carbon dioxide emissions during the clinker calcination stage. Based on material balance and adsorption-regeneration cycle characteristic analysis, the replacement amount of deactivated calcium-based adsorbent is determined to be 66.9 kg / t of finished cement. This value comprehensively considers the typical deactivation characteristics of the adsorbent after approximately 20 cycles (adsorption capacity less than 0.20 g CO2 / g adsorbent), its calcium substitution efficiency in the raw materials, and the actual CO2 capture efficiency of the entire carbonation-regeneration unit for kiln tail exhaust gas.

[0063] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the protection scope of this utility model and its equivalents, this utility model also intends to include these modifications and variations. The above-described embodiments are merely preferred embodiments given to fully illustrate this utility model, and their protection scope is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on this utility model are all within the protection scope of this utility model.

Claims

1. A negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution, characterized in that, Includes a solid waste-based adsorbent preparation module, a cement production module, and a calcium recycling carbon capture module; The cement production module includes a cement raw material batching unit, a cement raw material grinding module, a clinker calcination module, and a cement grinding module connected in sequence; the clinker calcination module includes a rotary kiln unit. The calcium circulating carbon capture module has its reactor feed port connected to the discharge port of the solid waste-based adsorbent preparation module, and its reactor air inlet connected to the exhaust port of the rotary kiln unit; and the calcium circulating carbon capture module is connected to the batching silo of the cement raw material batching unit through its discharge port.

2. The negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution according to claim 1, characterized in that, The reactor of the calcium circulating carbon capture module adopts a circulating fluidized bed, fixed bed, or moving bed device.

3. The negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution according to claim 1, characterized in that, The reactor of the calcium circulating carbon capture module adopts a circulating fluidized bed device, which includes a carbonation reactor and a regeneration reactor. The feeding port of the carbonation reactor is connected to the discharge port of the solid waste-based adsorbent preparation module, and its air inlet is connected to the tail gas outlet of the rotary kiln unit. The carbonation reactor and the regeneration reactor are connected by a conveying pipeline to form a circulation path, and the regeneration reactor is connected to the batching silo of the cement raw material batching unit through a discharge port.

4. The negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution according to claim 1, characterized in that, A heat exchanger is also provided between the rotary kiln unit and the calcium circulating carbon capture module.

5. The negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution according to claim 3, characterized in that, The tail gas outlet of the carbonation reactor is also equipped with a CO2 sensor.

6. The negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution according to claim 1, characterized in that, The discharge port of the solid waste-based adsorbent preparation module, the exhaust port of the rotary kiln unit, and the unloading port of the calcium circulating carbon capture module are all equipped with control valves.

7. The negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution according to claim 1, characterized in that, A calcium-based adsorbent storage chamber is also provided between the calcium cycle carbon capture module and the cement raw material batching unit.

8. The negative carbon cement production system based on solid waste calcium recycling carbon capture and cement raw material substitution according to claim 1, characterized in that, The clinker calcination module also includes a humidification tower unit, which is connected to the grinding unit in the cement raw material grinding module.

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