Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting i...Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting in severe ecological and environmental challenges.In response to this issue,this study pro-poses a novel approach for filling coal mine goafs using cementitious materials prepared by coal-based solid wastes mineralized with CO_(2)(15%in concentration).The CO_(2) sequestration capacities of individual solid wastes are ranked as follows:carbide slag(CS)>red mud(RM)>fly ash(FA).The performance of filling material prepared from composite solid waste(FA-CS-RM)mineralized with CO_(2) meets the filling requirements of goaf.The filling material(F60C20R20)obtained by CO_(2) mineralization was 14.9 MPa in maximum compressive strength,increasing by 32.2%compared to the non-mineralized material.The prepared filling material exhibits excellent CO_(2) sequestration capacity(i.e.,14.4 kg·t^(−1) in maximum amount of CO_(2) sequestration).According to the analysis of carbon sequestration potential,in China,the annual production of FA,CS,and RM is approximately 899,30,and 107 Mt,respectively in the year of 2023.The utilization of FA,CS,and RM individually can achieve carbon emission reductions of 3.42,10.78,and 0.61 Mt,respectively.The composite solid waste(FA-CS-RM)mineralized with CO_(2) can achieve 1.23 Mt in carbon emissions reduction.Additionally,taking Yellow River Basin of China as a case study,the total volume of underground space in coal mine goafs from 2016 to 2030 is estimated at 8.16 Gm3,indicating that this technology can sequester 0.18 Gt of CO_(2).This approach offers a promising solution for large-scale flue gas CO_(2) sequestration,recycling coal-based solid wastes,and remediating coal mine goafs,contributing to green utilization of coal and the emission reduction of carbon.展开更多
The natural gas(NG)reforming is currently one of the low-cost methods for hydrogen production.However,the mixture of H2 and CO_(2) in the produced gas inevitably includes CO_(2) and necessitates the costly CO_(2) sepa...The natural gas(NG)reforming is currently one of the low-cost methods for hydrogen production.However,the mixture of H2 and CO_(2) in the produced gas inevitably includes CO_(2) and necessitates the costly CO_(2) separation.In this work,a novel double chemical looping involving both combustion(CLC)and sorption-enhanced reforming(SE-CLR)was proposed towards the co-production of H2 and CO(CLC-SECLRHC)in two separated streams.CLC provides reactant CO_(2) and energy to feed SECLRHC,which generates hydrogen in a higher purity,as well as the calcium cycle to generate CO in a higher purity.Techno-economic assessment of the proposed system was conducted to evaluate its efficiency and economic competitiveness.Studies revealed that the optimal molar ratios of oxygen carrier(OC)/NG and steam/NG for reforming were recommended to be 1.7 and 1.0,respectively.The heat integration within CLC and SECLRHC units can be achieved by circulating hot OCs.The desired temperatures of fuel reactor(FR)and reforming reactor(RR)should be 850C and 600C,respectively.The heat coupling between CLC and SECLRHC units can be realized via a jacket-type reactor,and the NG split ratio for reforming and combustion was 0.53:0.47.Under the optimal conditions,the H2 purity,the H2 yield and the CH4 conversion efficiency were 98.76%,2.31 mol mol-1 and 97.96%,respectively.The carbon and hydrogen utilization efficiency respectively were 58.60% and 72.45%in terms of the total hydrogen in both steam and NG.The exergy efficiency of the overall process reached 70.28%.In terms of the conventional plant capacity(75 × 103 t y^(-1))and current raw materials price(2500$t^(-1)),the payback period can be 6.2 years and the IRR would be 11.5,demonstrating an economically feasible and risk resistant capability.展开更多
China is the largest coke producer and consumer.There is a pressing need to address the high emissions of air pollutants and carbon dioxide associated with traditional coking production.As the nation pursues a transit...China is the largest coke producer and consumer.There is a pressing need to address the high emissions of air pollutants and carbon dioxide associated with traditional coking production.As the nation pursues a transition towards carbon neutrality,expanding supply chains for coking plants to produce hydrogen,methanol,and other green alternatives has garnered significant attention.However,the relative advantages of these strategies have remained uncertain.In this study,we integrate a life cycle assessmenteconomic analysis-scenario analysis model to evaluate various coke oven gas(COG)utilization routes(COGtM:COG-to-methanol,COGtLNG:COG-to-liquefied natural gas,COGtSA:COG-to-synthetic ammonia,and COGtH:COG-to-hydrogen).The results indicate that COGtSA emerges as the preferred option for balancing environmental and economic benefits.Meanwhile,COGtM demonstrates economic viability but is associated with higher environmental impacts.Despite being recognized as a significant strategic direction under carbon neutrality initiatives,COGtH faces economic feasibility and risk resilience limitations.COGtLNG encounters both financial and environmental challenges,necessitating strategic development from an energy security perspective.The projected coking capacity is anticipated to experience a slight increase in the mid-term yet a significant decline in the long term,influenced by steel production capacity.In potential future markets,COGtM is estimated to potentially capture a maximum market share of 16e34%in the methanol market.Furthermore,against the backdrop of continuously expanding potential demand for hydrogen,COGtH holds advantages as a transitional solution,but in the long run,it can only meet a small portion of the market.COGtSA can meet 7e14%of market demand and emerges as the most viable pathway from the viewpoint of balancing environmental and economic aspects and covering future markets.展开更多
基金supported by the National Natural Science Foundation of China(U21A20321 and 22378241)Research Project Supported by Shanxi Scholarship Council of China(2024-015).
文摘Coal is an essential component of global energy;however,the processes of coal mining and utilization produce significant amounts of coal mine goafs,accompanied by coal-based solid wastes and emitted CO_(2),resulting in severe ecological and environmental challenges.In response to this issue,this study pro-poses a novel approach for filling coal mine goafs using cementitious materials prepared by coal-based solid wastes mineralized with CO_(2)(15%in concentration).The CO_(2) sequestration capacities of individual solid wastes are ranked as follows:carbide slag(CS)>red mud(RM)>fly ash(FA).The performance of filling material prepared from composite solid waste(FA-CS-RM)mineralized with CO_(2) meets the filling requirements of goaf.The filling material(F60C20R20)obtained by CO_(2) mineralization was 14.9 MPa in maximum compressive strength,increasing by 32.2%compared to the non-mineralized material.The prepared filling material exhibits excellent CO_(2) sequestration capacity(i.e.,14.4 kg·t^(−1) in maximum amount of CO_(2) sequestration).According to the analysis of carbon sequestration potential,in China,the annual production of FA,CS,and RM is approximately 899,30,and 107 Mt,respectively in the year of 2023.The utilization of FA,CS,and RM individually can achieve carbon emission reductions of 3.42,10.78,and 0.61 Mt,respectively.The composite solid waste(FA-CS-RM)mineralized with CO_(2) can achieve 1.23 Mt in carbon emissions reduction.Additionally,taking Yellow River Basin of China as a case study,the total volume of underground space in coal mine goafs from 2016 to 2030 is estimated at 8.16 Gm3,indicating that this technology can sequester 0.18 Gt of CO_(2).This approach offers a promising solution for large-scale flue gas CO_(2) sequestration,recycling coal-based solid wastes,and remediating coal mine goafs,contributing to green utilization of coal and the emission reduction of carbon.
基金supported by National Natural Science Foundation of China(U1810205)The authors would also like to thank the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20220003)Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2021L002)for their support.
文摘The natural gas(NG)reforming is currently one of the low-cost methods for hydrogen production.However,the mixture of H2 and CO_(2) in the produced gas inevitably includes CO_(2) and necessitates the costly CO_(2) separation.In this work,a novel double chemical looping involving both combustion(CLC)and sorption-enhanced reforming(SE-CLR)was proposed towards the co-production of H2 and CO(CLC-SECLRHC)in two separated streams.CLC provides reactant CO_(2) and energy to feed SECLRHC,which generates hydrogen in a higher purity,as well as the calcium cycle to generate CO in a higher purity.Techno-economic assessment of the proposed system was conducted to evaluate its efficiency and economic competitiveness.Studies revealed that the optimal molar ratios of oxygen carrier(OC)/NG and steam/NG for reforming were recommended to be 1.7 and 1.0,respectively.The heat integration within CLC and SECLRHC units can be achieved by circulating hot OCs.The desired temperatures of fuel reactor(FR)and reforming reactor(RR)should be 850C and 600C,respectively.The heat coupling between CLC and SECLRHC units can be realized via a jacket-type reactor,and the NG split ratio for reforming and combustion was 0.53:0.47.Under the optimal conditions,the H2 purity,the H2 yield and the CH4 conversion efficiency were 98.76%,2.31 mol mol-1 and 97.96%,respectively.The carbon and hydrogen utilization efficiency respectively were 58.60% and 72.45%in terms of the total hydrogen in both steam and NG.The exergy efficiency of the overall process reached 70.28%.In terms of the conventional plant capacity(75 × 103 t y^(-1))and current raw materials price(2500$t^(-1)),the payback period can be 6.2 years and the IRR would be 11.5,demonstrating an economically feasible and risk resistant capability.
基金financially supported by the Science and Technology Strategic Research Special Project of Shanxi Province(202204031401048)the Fundamental Research Program of Shanxi Province(202103021223027)+2 种基金the National Natural Science Foundation of China(72025401)the Ordos-Tsinghua Innovative&Collaborative Research Program in Carbon NeutralityFund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20220003)for their support。
文摘China is the largest coke producer and consumer.There is a pressing need to address the high emissions of air pollutants and carbon dioxide associated with traditional coking production.As the nation pursues a transition towards carbon neutrality,expanding supply chains for coking plants to produce hydrogen,methanol,and other green alternatives has garnered significant attention.However,the relative advantages of these strategies have remained uncertain.In this study,we integrate a life cycle assessmenteconomic analysis-scenario analysis model to evaluate various coke oven gas(COG)utilization routes(COGtM:COG-to-methanol,COGtLNG:COG-to-liquefied natural gas,COGtSA:COG-to-synthetic ammonia,and COGtH:COG-to-hydrogen).The results indicate that COGtSA emerges as the preferred option for balancing environmental and economic benefits.Meanwhile,COGtM demonstrates economic viability but is associated with higher environmental impacts.Despite being recognized as a significant strategic direction under carbon neutrality initiatives,COGtH faces economic feasibility and risk resilience limitations.COGtLNG encounters both financial and environmental challenges,necessitating strategic development from an energy security perspective.The projected coking capacity is anticipated to experience a slight increase in the mid-term yet a significant decline in the long term,influenced by steel production capacity.In potential future markets,COGtM is estimated to potentially capture a maximum market share of 16e34%in the methanol market.Furthermore,against the backdrop of continuously expanding potential demand for hydrogen,COGtH holds advantages as a transitional solution,but in the long run,it can only meet a small portion of the market.COGtSA can meet 7e14%of market demand and emerges as the most viable pathway from the viewpoint of balancing environmental and economic aspects and covering future markets.
