Cement kiln substitute fossil fuel CO2 reduction model and dynamic optimization method

Abstract

The invention discloses a cement kiln substitute fossil fuel CO2 reduction model and a dynamic optimization method, and the method comprises the steps: calculating the CO2 emission in a combustion stage when all fossil fuel participates in combustion, calculating the total CO2 emission of corresponding fuel after the fossil fuel is substituted in the combustion stage, determining the CO2 emission reduction in the combustion stage after the fossil fuel is substituted in the cement kiln, and determining the CO2 emission reduction in the combustion stage after the fossil fuel is substituted in the cement kiln. The carbon reduction amount is dynamically corrected by introducing the power generation amount change of waste heat power generation before and after fuel replacement, and a basic CO2 reduction model is established; the comprehensive cost is minimized by adjusting fuel types and substitution proportions, and an environment-friendly-economic dynamic optimization model is established; the model design logic is rigorous, it is ensured that the emission reduction result has traceability and authority, the application scene is clear, the method can be directly integrated to an existing cement kiln production line, the original production scale and core technology do not need to be changed, the technical transformation threshold of an enterprise is lowered, and the method has remarkable engineering popularization value.

Description

Technical Field

[0001] This invention relates to cement kiln fuel substitution technology, specifically to a model and dynamic optimization method for reducing CO2 emissions from replacing fossil fuels in cement kilns. Background Technology

[0002] As the global climate crisis continues to intensify, the international community is imposing increasingly stringent requirements on greenhouse gas emissions control. As the world's largest emitter of carbon, my country faces unprecedented challenges in carbon reduction. It must shoulder the responsibilities commensurate with its stage of development while simultaneously seeking a balance between economic growth and ecological protection. Carbon reduction has become a strategic issue concerning the country's sustainable development. Cement, as one of the world's basic building materials, is widely used. my country's cement production level ranks among the world's top, but the cement production process involves energy consumption and pollutant emissions, making it extremely challenging for the cement industry to achieve peak carbon emissions and carbon neutrality.

[0003] Cement kiln fuel substitution technologies, by using biomass and other alternatives to replace traditional fossil fuels, can effectively reduce fossil fuel consumption and thus achieve carbon emission reduction. This is one of the key technological directions to help the cement industry achieve its "dual carbon" goals. However, existing technologies lack precise mathematical models to quantify emission reduction effects, resulting in a lack of reliable data support for scenarios such as carbon emission trading and policy subsidies. For example, the report "Research and Application of Green and Low-Carbon Technology Innovation by Conch Cement" published on China Cement Network has verified the feasibility of a straw crushing and combustion system, but has not disclosed its emission reduction calculation logic. Another example is the Chinese patent "A Method for Deashing Biomass by Recycling Acetic Acid Lamination" (Publication No.: CN119371999A), which discloses a method including biomass deashing pretreatment steps, but does not link it to carbon emission calculations. Existing technologies remain in a state of flux in terms of quantifying carbon emission reduction. Summary of the Invention

[0004] To better predict CO2 (carbon dioxide) emission reduction before and after cement kilns replace fossil fuels, this invention provides a CO2 reduction model and dynamic optimization method for cement kilns replacing fossil fuels. It provides a mathematical model that accurately quantifies the CO2 emission reduction effect before and after fuel replacement, and adjusts the replacement ratio of different fuels in real time to respond to variable factors such as carbon price fluctuations, fuel price fluctuations, and changes in grid carbon factors. This provides cement enterprises with a quantifiable assessment of the CO2 emission reduction capacity and economic efficiency of different fuels under different replacement ratios, enabling dynamic optimal decision-making.

[0005] The objective of this invention is achieved as follows: A model and dynamic optimization method for reducing CO2 emissions from cement kilns as fossil fuel substitutes, characterized by the following steps: 1) Calculate the CO2 emissions during the combustion phase when all fossil fuels are used in combustion; 1.1 Conduct a component ratio analysis of fossil fuels to obtain the average lower heating value of fossil fuels; 1.2 Calculate the fossil fuel activity level based on the above average lower heating value, net consumption of fossil fuels, and combustion efficiency; 1.3 Calculate the CO2 emission factor of fossil fuels based on the carbon content per unit calorific value, the carbon oxidation rate of the fuel, and the ratio of the relative molecular masses of CO2 to C. 1.4 Based on the fossil fuel activity level and the CO2 emission factor of fossil fuels obtained in steps 1.2 and 1.3, determine the CO2 emissions of all fossil fuels during the combustion stage; 2) Calculate the CO2 emissions of the corresponding fuel during the combustion stage after replacing fossil fuels, using the method in step 1) to determine the CO2 emissions of the corresponding fuel during the combustion stage; 3) Determine the CO2 emission reduction after replacing fossil fuels with cement kilns based on the CO2 emissions of fossil fuels during the combustion stage obtained in steps 1) and 2) and the total CO2 emissions of the corresponding fuels during the combustion stage after replacing fossil fuels. 4) Following step 3), introduce the changes in power generation from waste heat before and after fuel substitution to dynamically correct carbon reduction and establish a basic CO2 reduction model; 5) Following step 4), introduce the environmental-economic weight coefficient to balance carbon emission targets and costs, and introduce fuel unit price, purchased electricity price and carbon trading price to calculate the comprehensive cost of fuel substitution schemes. Under constraints, minimize the comprehensive cost by adjusting fuel type and substitution ratio, and establish an environmental-economic dynamic optimization model. 6) Following the method in step 1), perform the following calculations: (1) Calculate the level of fossil fuel activity: (1) In the formula: fossil fuel The activity level is expressed in GJ; The lower heating value of fossil fuels is expressed in GJ / t. This represents the net consumption of fossil fuels, expressed in tons (t). The combustion efficiency of fossil fuels is expressed as % (%). Indicates the type of fossil fuel; (2) Calculate the CO2 emission factor of fossil fuels: (2) In the formula: The CO2 emission factor for fossil fuels is expressed in tCO2 / GJ. Carbon content per unit heat of fossil fuels, expressed in t / GJ; The carbon oxidation rate of fossil fuels, expressed as % This is the ratio of the relative molecular masses of CO2 to C. (3) Calculate the CO2 emissions during the combustion stage when all fossil fuels are involved in combustion: (3) In the formula: This represents the CO2 emissions from the combustion of all fossil fuels, expressed in tons of CO2 (tCO2). 7) Following the method in step 1), calculate the CO2 emissions of the corresponding fuel during the combustion stage after replacing fossil fuels: (1) Calculate the activity levels of different fuels at different substitution ratios: (4) In the formula: The activity level of fuel j at a substitution ratio k is expressed in GJ. The lower heating value of the fuel is expressed in GJ / t. The figure represents the net consumption of fossil fuels before replacement, expressed in tons (t). For the j-th type of fuel Substitution ratio; The optimal mass ratio for fuel; Here, represents the combustion efficiency of the fuel, expressed as %; j represents the type of fuel; and k represents the substitution ratio, expressed as %; (2) Calculate the CO2 emission factors of different fuels at different substitution ratios: (5) In the formula: is the CO2 emission factor of fuel j at a substitution ratio k, expressed in tCO2 / GJ; Carbon content per unit heat of fuel, expressed in t / GJ; The carbon oxidation rate of the fuel, expressed as % (3) Calculate the total CO2 emissions during the combustion stage when different fuels participate in combustion at different substitution ratios: (6) In the formula: The total CO2 emissions during the combustion stage when different fuels j participate in combustion at different substitution ratios k is expressed in tCO2. 8) Establish a basic quantitative model for CO2 emission reduction, the formula of which is as follows: (7) In the formula: △C is the total CO2 emission reduction before and after replacing all fossil fuels, in tCO2 / year; β is the grid carbon emission factor, in kgCO2 / kWh; This represents the change in waste heat power generation, expressed in kWh / year. 9) Establish an environmental protection-economic dynamic optimization model, the formula of which is as follows; (8) In the formula: M represents the combined benefit of carbon emission reduction and electricity consumption costs from replacing fossil fuels, expressed in yuan; α is the environmental-economic weighting coefficient. ; The price is for carbon trading, expressed in yuan / ton. Let be the unit cost of the j-th fuel, expressed in yuan / GJ (yuan / t). The on-grid electricity price for waste heat power generation is expressed in yuan / kWh. Constraints: (1) Perform thermal equilibrium constraints; (9) In the formula: To meet the minimum heat requirements for kiln production, the unit is GJ; (2) Apply substitution ratio constraints: (10) In the formula: This represents the minimum fuel substitution rate, expressed as a percentage (%). This represents the maximum percentage of fuel substitution, expressed as a percentage (%). (3) Implement combustion efficiency constraints: (11) In the formula: Let be the combustion efficiency of the j-th fuel, expressed in % . To determine the combustion efficiency of replacing all fossil fuels, expressed in %, a CO2 reduction model and an environmental-economic dynamic optimization model were established.

[0006] This invention constructs a CO2 reduction model for cement kilns after replacing fossil fuels. It incorporates changes in power generation for dynamic correction of emission reductions, effectively avoiding calculation errors and making the model's calculation results more closely reflect the actual production conditions of cement kilns, further improving data accuracy and achieving precise quantification of the CO2 emission reduction effect after replacement. Simultaneously, it constructs an environmental-economic dynamic optimization model that can adapt in real time to variable factors such as carbon price fluctuations, fuel price changes, and grid carbon factor adjustments, dynamically optimizing the blending ratio of different alternative fuels. This supports enterprises in quantitatively assessing the emission reduction potential, costs, and benefits of different replacement strategies, providing data-driven support for production decisions. Based on scientific calculation logic, it ensures the traceability and authority of emission reduction results, and has a clear application scenario. It can be directly integrated into existing cement kiln production lines without changing the original production scale and core processes, lowering the technological transformation threshold for enterprises and possessing significant engineering promotion value. Attached Figure Description

[0007] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0008] The specific embodiments of the present invention will be described in detail below. See also Figure 1 A CO2 reduction model and dynamic optimization method for replacing fossil fuels in cement kilns are proposed, applicable to all stages of cement kiln production lines before and after adopting alternative fuels. Under the premise that the scale and other conditions of the cement production line remain unchanged before and after adopting alternative fuels, the activity level of the fuel is calculated using the average lower heating value of the fuel and the net fuel consumption. Then, based on the CO2 emission factor corresponding to the fuel during the combustion stage, the CO2 emissions during the combustion stage before and after replacement are calculated, and the difference between the two is obtained. The change in power generation from waste heat before and after fuel replacement is introduced to dynamically correct the total CO2 emission reduction, establishing a basic CO2 reduction model. Simultaneously, an environmental-economic weight coefficient is introduced to balance carbon emission targets and costs, and the comprehensive cost of the fuel replacement scheme is calculated using fuel unit price, purchased electricity price, and carbon trading price. Under constraints, the comprehensive cost is minimized by adjusting the type and proportion of alternative fuels, establishing an environmental-economic dynamic optimization model.

[0009] This invention uses biomass fuel to partially replace fossil fuels in the combustion process. This replacement occurs only in the decomposition furnace, while all other operating conditions remain unchanged. The steps are as follows: 1) Calculate the CO2 emissions during the combustion phase when all fossil fuels are used in combustion; 1.1 Conduct a component ratio analysis of the fuel to obtain the average lower heating value of the fossil fuel, 101; 1.2 Based on the above average lower heating value, net fuel consumption, and combustion efficiency, calculate the fuel activity level 102; 1.3 Calculate the CO2 emission factor 103 of fossil fuels based on the carbon content per unit calorific value of fossil fuels, the carbon oxidation rate of fuels, and the ratio of the relative molecular masses of CO2 to C. 1.4 Based on the fossil fuel activity level and the fossil fuel CO2 emission factor obtained in steps 1.2 and 1.3, determine the CO2 emission amount of the corresponding fuel during the combustion stage 104; 2) Calculate the CO2 emissions of the corresponding fuel during the combustion stage after replacing fossil fuels. Use the method in step 1) to determine the CO2 emissions of the corresponding fuel during the combustion stage 105; 3) Based on the CO2 emissions of fossil fuels during the combustion stage obtained in steps 1) and 2), and the total CO2 emissions of the corresponding fuels during the combustion stage after replacing fossil fuels, determine the CO2 emission reduction of cement kilns after replacing fossil fuels by 106. 4) Following step 3), introduce the change in power generation from waste heat before and after fuel substitution to dynamically correct the carbon reduction and establish a basic CO2 reduction model 107. 5) Following step 4), introduce the environmental-economic weight coefficient to balance carbon emission targets and costs, and introduce fuel unit price, purchased electricity price and carbon trading price to calculate the comprehensive cost of fuel substitution schemes. Under constraints, minimize the comprehensive cost by adjusting fuel type and substitution ratio, and establish an environmental-economic dynamic optimization model 108. 6) Following the method in step 1), perform the following calculations: (1) Calculate the level of fossil fuel activity ; (1) In the formula: fossil fuel The activity level is expressed in GJ; The lower heating value of fossil fuels is expressed in GJ / t. This represents the net consumption of fossil fuels, expressed in tons (t). The combustion efficiency of fossil fuels is expressed as % (%). Indicates the type of fossil fuel.

[0010] (2) Calculate the CO2 emission factor of fossil fuels : (2) In the formula: The CO2 emission factor for fossil fuels is expressed in tCO2 / GJ. Carbon content per unit heat of fossil fuels, expressed in t / GJ; The carbon oxidation rate of fossil fuels, expressed as % This is the ratio of the relative molecular masses of CO2 to C.

[0011] (3) Calculate the CO2 emissions during the combustion stage when all fossil fuels are involved in combustion. : (3) In the formula: This represents the CO2 emissions from the combustion of all fossil fuels, expressed in tons of CO2 (tCO2).

[0012] 7) Following the method in step 1), calculate the CO2 emissions of the corresponding fuel during the combustion stage after replacing fossil fuels: (1) Calculate the activity level of different fuels at different substitution ratios. : (4) In the formula: For fuel j in the substitution ratio The activity level is expressed in GJ; The lower heating value of the fuel is expressed in GJ / t. The figure represents the net consumption of fossil fuels before replacement, expressed in tons (t). The k-th substitution ratio for the j-th fuel; The optimal mass ratio for fuel; ρ represents the combustion efficiency of the fuel, expressed as %; j represents the type of fuel; k represents the substitution ratio, expressed as %.

[0013] (2) Calculate the CO2 emission factor of different fuels under different substitution ratios. : (5) In the formula: is the CO2 emission factor of fuel j at a substitution ratio k, expressed in tCO2 / GJ; Carbon content per unit heat of fuel, expressed in t / GJ; The carbon oxidation rate of the fuel, expressed as % (3) Calculate the total CO2 emissions during the combustion stage when different fuels participate in combustion at different substitution ratios: (6) In the formula: This represents the total CO2 emissions during the combustion phase when different fuels j participate in combustion at different substitution ratios k, expressed in tCO2. Table 1 presents a comparative analysis of pulverized coal and biomass fuels in industrial applications, providing compositional analysis data and lower heating values ​​for pulverized coal and blended biomass fuels. Table 2 lists relevant technical parameters before and after fuel substitution in the precalciner, providing operational data for cement production lines and data related to biomass substitution, including precalciner coal consumption, biomass substitution ratio, optimal mass ratio, C content and oxidation rate of pulverized coal and biomass fuels, and combustion efficiency of pulverized coal and biomass fuels. Based on the data in Tables 1 and 2, the activity level and CO2 emission factor of the corresponding fuels before and after fossil fuel substitution can be calculated, as well as the CO2 emissions of the corresponding fuels during the combustion stage before and after fossil fuel substitution.

[0014] ; ; 8) Establish a basic CO2 emission reduction model, the formula of which is as follows: (7) In the formula: △C is the total CO2 emission reduction before and after replacing all fossil fuels, in tCO2 / year; β is the grid carbon emission factor, in kgCO2 / kWh; This represents the change in waste heat power generation, expressed in kWh / year.

[0015] Table 3 shows the relevant parameters for waste heat power generation, including grid carbon emission factors, annual increase in power generation, and annual operating hours. Based on Table 3, the total CO2 emission reduction during the combustion phase of the corresponding fuel after replacing fossil fuels can be calculated.

[0016] ; 9) Establish an environmental protection-economic dynamic optimization model, the formula of which is as follows: (8) In the formula: M represents the combined benefit of emission reduction and electricity consumption costs from replacing fossil fuels, expressed in yuan; α is the environmental-economic weighting coefficient. ; The price is for carbon trading, expressed in yuan / ton. Let be the unit cost of the j-th type of fuel, expressed in yuan / t (yuan / GJ). The on-grid electricity price for waste heat power generation is expressed in yuan / kWh. Wherein, α is the environmental-economic weighting coefficient, which is adjusted to respond in real time to carbon emission reduction policies (such as when carbon taxes are increased). or fluctuations in fuel prices (such as when biomass prices decrease). This invention focuses on emission reduction as its optimization objective, therefore a=0.6 is selected, and the optimization objective is 60% carbon reduction benefit + 40% cost increase; The coupling purpose is to adjust the power consumption of biomass pretreatment in a timely manner when it is high (such as crushing and drying wet straw). Weigh the additional electricity emissions against the emission reduction benefits of replacing coal; Table 4 provides data on carbon prices, biomass comprehensive costs, coal comprehensive costs, and grid-connected electricity prices in 2025, which can be used to calculate the comprehensive benefits of cement kilns replacing fossil fuels.

[0017] ; The constraints include: thermal balance constraints, substitution ratio constraints, and combustion efficiency constraints. (1) Perform thermal equilibrium constraints: (9) In the formula: To meet the minimum heat requirements for kiln production, the unit is GJ; (2) Apply substitution ratio constraints: (10) In formula (10): This represents the minimum fuel substitution rate, expressed as a percentage (%). This represents the maximum percentage of fuel substitution, expressed as a percentage (%). (3) Implement combustion efficiency constraints: (11) In the formula: Let be the combustion efficiency of the j-th fuel, expressed in % . The combustion efficiency of replacing all fossil fuels is expressed in % (%). The above constraints decouple fuel characteristics (calorific value), process limitations (efficiency), and blending ratios into independent constraint blocks, facilitating modular optimization. In this invention, biomass fuel replaces a portion of pulverized coal in the decomposition furnace for combustion, and the total calorific value of the fuel participating in combustion must not be less than the minimum heat requirement for the decomposition furnace; furthermore, the biomass fuel substitution rate cannot exceed 60% of the theoretical coal substitution limit for the decomposition furnace; simultaneously, the combustion efficiency of the fuel participating in combustion in the decomposition furnace must not be less than 90%, i.e., ≥90%.

[0018] Following the method in step 1), calculate the CO2 emissions during the combustion phase when all fossil fuels are involved in combustion:

[0019] (1) Calculate the activity level of pulverized coal fuel: ; (2) Calculate the CO2 emission factor of pulverized coal fuel: ; (3) Calculate the CO2 emissions of pulverized coal during the combustion stage: ; Following the method in step 1), calculate the CO2 emissions of the corresponding fuel during the combustion stage after replacing fossil fuels: (1) Calculate the activity level of different fuels at different substitution ratios. ; (1.1) Calculate the activity level of biomass fuel ; (1.2) Calculate the activity level of pulverized coal fuel ; (2) Calculate the CO2 emission factor of different fuels under different substitution ratios. ; (2.1) Calculate the CO2 emission factor of biomass fuel Since biomass fuel is considered a zero-carbon resource, therefore biomass fuel ; (2.2) Calculate the CO2 emission factor of pulverized coal fuel =26.37 / 1000×0.98×44 / 12=0.0947563t / GJ; (3) Calculate the total CO2 emissions of the corresponding fuel during the combustion stage after replacing fossil fuels. ; Calculate the total CO2 emission reduction before and after replacing fossil fuels: △C = (38.78104 - 27.14673) × 8160 + 0.5366 / 1000 × 1105.4 × 10000 = 100,868 tCO2 / a; Calculation results show that when biomass fuel replaces 30% of pulverized coal in the decomposition furnace system, the annual CO2 emission reduction is 100,900 tons of CO2, and the carbon reduction effect of biomass fuel replacing pulverized coal combustion is very significant.

[0020] Calculate the overall benefits of replacing fossil fuels, including emissions reductions and electricity costs: (1) Cost items: Increase in biomass costs = 290 × 5 × 0.3 × 1.9 × 3600 / 1000 × 8160 / 10000 = 24,279,264 yuan / year; Increase in coal costs = 650 × (-5 × 0.3 × 3600 / 1000) × 8160 / 10000 = (-2864.18) million yuan / year; Electricity cost increase = 0.6 × (-1105.4) = (-663.24) million yuan / year; (2) Revenue items: Carbon reduction benefit = 60.63 × (-10.0868) = (-611.5627) million yuan / year; (3) Calculate the comprehensive revenue after replacing 30% of coal powder with biomass fuel M = 0.6 × (-611.5627) + (1 - 0.6) × (2427.9264 + (-2864.18) + (-663.24)) = (-806.7351) million yuan / year; The calculation result is negative, indicating that the annual net income of the decomposition furnace after replacing 30% of the coal powder with biomass fuel is 6,961,950.4 yuan, which is very economically beneficial.

[0021] (4) Verify constraints: (4.1) Verify thermal equilibrium constraints: The total calorific value of the fuel participating in combustion in the decomposition furnace after co-firing biomass fuel = 18.4998 × 5 × 0.3 × 1.9 + 23.934 × 5 × 0.7 = 136.49343 MJ / s; The total calorific value of the fuel participating in combustion in the decomposition furnace during pulverized coal combustion is 23.934 × 5 = 119.67 MJ / s; 136.49343>119.67≥ This satisfies the thermal balance constraint; (4.2) Verify the substitution ratio constraint: 0 < 30% < 60%, satisfying the substitution ratio constraint; (4.3) Verify combustion efficiency constraints: (91%×0.3+95%×0.7)=93%>90%, which meets the combustion efficiency constraint; This environmental-economic dynamic optimization model can respond to changes in fuel prices in real time. If the price of biomass fuel rises sharply, the model will automatically reduce the replacement ratio. To maintain economic viability, and in response to policy changes, such as an increase in carbon tax, the environmental-economic weighting coefficient α can be increased to ensure emission reduction benefits. Finally, considering process technology, if optimization shows that combustion efficiency does not meet constraints, fuel pretreatment technology can be improved to increase combustion efficiency. Through this model, relevant enterprises can quantitatively assess the carbon emission reduction potential and economic viability of different blending strategies, achieving dynamic optimization decisions.

[0022] This invention constructs a CO2 reduction model for fossil fuel substitution in cement kilns, achieving for the first time a precise quantification of CO2 emission reduction effects after fossil fuel substitution, providing reliable data support for scenarios such as carbon emission trading and policy subsidies. An environmental-economic dynamic optimization model is established, capable of adapting in real-time to variable factors such as carbon price fluctuations, changes in the prices of alternative fuels and fossil fuels, and adjustments to grid carbon factors. It dynamically optimizes the substitution ratio of different alternative fuels, helping enterprises achieve production decisions that maximize economic benefits while meeting environmental requirements. The invention creatively introduces changes in power generation from waste heat before and after fuel substitution to dynamically correct CO2 emission reductions, effectively avoiding calculation errors caused by power generation fluctuations, making the calculation results more consistent with the actual production conditions of cement kilns, and further improving the accuracy of CO2 emission reduction data. It supports enterprises in quantitatively assessing the carbon emission reduction potential, cost input, and return on investment of different substitution strategies, providing a data-driven basis for production decisions. The logic is rigorous, based on scientific calculations of fuel activity levels and emission factors, ensuring the traceability and authority of CO2 emission reduction results. Based on a cement kiln production scale of 5000t / d, when the biomass replacement rate in the decomposition furnace reaches 30%, the annual emission reduction rate can reach 31.87%. The application scenario is clear, and it can be directly integrated into the existing cement kiln production line without changing the original production scale and core process, thus lowering the threshold for enterprise technological transformation and possessing significant engineering promotion value.

Claims

1. A CO2 reduction model and dynamic optimization method for cement kilns replacing fossil fuels, characterized by the following steps: 1) Calculate the CO2 emissions during the combustion phase when all fossil fuels are used in combustion; 1.1 Conduct a component ratio analysis of fossil fuels to obtain the average lower heating value of fossil fuels; 1.2 Calculate the fossil fuel activity level based on the above average lower heating value, net consumption of fossil fuels, and combustion efficiency; 1.3 Calculate the CO2 emission factor of fossil fuels based on the carbon content per unit calorific value, the carbon oxidation rate of the fuel, and the ratio of the relative molecular masses of CO2 to C. 1.4 Based on the fossil fuel activity level and the CO2 emission factor of fossil fuels obtained in steps 1.2 and 1.3, determine the CO2 emissions of all fossil fuels during the combustion stage; 2) Calculate the CO2 emissions of the corresponding fuel during the combustion stage after replacing fossil fuels, using the method in step 1) to determine the CO2 emissions of the corresponding fuel during the combustion stage; 3) Determine the CO2 emission reduction after replacing fossil fuels with cement kilns based on the CO2 emissions of fossil fuels during the combustion stage obtained in steps 1) and 2) and the total CO2 emissions of the corresponding fuels during the combustion stage after replacing fossil fuels. 4) Following step 3), introduce the changes in power generation from waste heat before and after fuel substitution to dynamically correct carbon reduction and establish a basic CO2 reduction model; 5) Following step 4), introduce the environmental-economic weight coefficient to balance carbon emission targets and costs, and introduce fuel unit price, purchased electricity price and carbon trading price to calculate the comprehensive cost of fuel substitution schemes. Under constraints, minimize the comprehensive cost by adjusting fuel type and substitution ratio, and establish an environmental-economic dynamic optimization model. 6) Following the method in step 1), perform the following calculations: (1) Calculate the level of fossil fuel activity: （1） In the formula: fossil fuel The activity level is expressed in GJ; The lower heating value of fossil fuels is expressed in GJ / t. This represents the net consumption of fossil fuels, expressed in tons (t). The combustion efficiency of fossil fuels is expressed as % (%). Indicates the type of fossil fuel; (2) Calculate the CO2 emission factor of fossil fuels: （2） In the formula: The CO2 emission factor for fossil fuels is expressed in tCO2 / GJ. Carbon content per unit heat of fossil fuels, expressed in t / GJ; The carbon oxidation rate of fossil fuels, expressed as % This is the ratio of the relative molecular masses of CO2 to C. (3) Calculate the CO2 emissions during the combustion stage when all fossil fuels are involved in combustion: （3） In the formula: CO2 emissions from the combustion of all fossil fuels, expressed in tons of CO2 (tCO2). 7) Following the method in step 1), calculate the CO2 emissions of the corresponding fuel during the combustion stage after replacing fossil fuels: (1) Calculate the activity levels of different fuels at different substitution ratios: (4) In the formula: The activity level of fuel j at a substitution ratio k is expressed in GJ. The lower heating value of the fuel is expressed in GJ / t. The net consumption of fossil fuels before replacement is expressed in tons (t). For the j-th type of fuel Substitution ratio; The optimal mass ratio for fuel; Here, represents the combustion efficiency of the fuel, expressed as %; j represents the type of fuel; and k represents the substitution ratio, expressed as %; 2) Calculate the CO2 emission factors for different fuels at different substitution ratios: (5) In the formula: is the CO2 emission factor of fuel j at a substitution ratio k, expressed in tCO2 / GJ; Carbon content per unit heat of fuel, expressed in t / GJ; The carbon oxidation rate of the fuel, expressed as % (3) Calculate the total CO2 emissions during the combustion stage when different fuels participate in combustion at different substitution ratios: （6） In the formula: The total CO2 emissions during the combustion stage when different fuels j participate in combustion at different substitution ratios k is expressed in tCO2. 8) Establish a basic CO2 emission reduction model, the formula of which is as follows: (7) In the formula: △C is the total CO2 emission reduction before and after replacing all fossil fuels, in tCO2 / year; β is the grid carbon emission factor, in kgCO2 / kWh; This represents the change in waste heat power generation, expressed in kWh / year. 9) Establish an environmental protection-economic dynamic optimization model, the formula of which is as follows; (8) In the formula: M represents the combined benefit of carbon emission reduction and electricity consumption costs from replacing fossil fuels, in yuan; α is the environmental-economic weighting coefficient. ; The price is for carbon trading, expressed in yuan / ton. Let be the unit cost of the j-th fuel, expressed in yuan / GJ (yuan / t). The on-grid electricity price for waste heat power generation is expressed in yuan / kWh. Constraints: (1) Perform thermal equilibrium constraints: (9) In the formula: To meet the minimum heat requirements for kiln production, the unit is GJ; (2) Apply substitution ratio constraints: （10） In the formula: This represents the minimum fuel substitution rate, expressed as a percentage (%). This represents the maximum percentage of fuel substitution, expressed as a percentage (%). (3) Implement combustion efficiency constraints: （11） In the formula: Let be the combustion efficiency of the j-th fuel, expressed in % . To determine the combustion efficiency of replacing all fossil fuels, expressed in %, a CO2 reduction model and an environmental-economic dynamic optimization model were established.

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