Porous materials present significant advantages for absorbing radioactive isotopes in nuclear waste streams.To improve absorption efficiency in nuclear waste treatment,a thorough understanding of the diffusion-advecti...Porous materials present significant advantages for absorbing radioactive isotopes in nuclear waste streams.To improve absorption efficiency in nuclear waste treatment,a thorough understanding of the diffusion-advection process within porous structures is essential for material design.In this study,we present advancements in the volumetric lattice Boltzmann method(VLBM)for modeling and simulating pore-scale diffusion-advection of radioactive isotopes within geopolymer porous structures.These structures are created using the phase field method(PFM)to precisely control pore architectures.In our VLBM approach,we introduce a concentration field of an isotope seamlessly coupled with the velocity field and solve it by the time evolution of its particle population function.To address the computational intensity inherent in the coupled lattice Boltzmann equations for velocity and concentration fields,we implement graphics processing unit(GPU)parallelization.Validation of the developed model involves examining the flow and diffusion fields in porous structures.Remarkably,good agreement is observed for both the velocity field from VLBM and multiphysics object-oriented simulation environment(MOOSE),and the concentration field from VLBM and the finite difference method(FDM).Furthermore,we investigate the effects of background flow,species diffusivity,and porosity on the diffusion-advection behavior by varying the background flow velocity,diffusion coefficient,and pore volume fraction,respectively.Notably,all three parameters exert an influence on the diffusion-advection process.Increased background flow and diffusivity markedly accelerate the process due to increased advection intensity and enhanced diffusion capability,respectively.Conversely,increasing the porosity has a less significant effect,causing a slight slowdown of the diffusion-advection process due to the expanded pore volume.This comprehensive parametric study provides valuable insights into the kinetics of isotope uptake in porous structures,facilitating the de展开更多
Spraying test were conducted twice before steel slabs were put into the furnace and the effects of the oxidation resistance coating were investigated and verified. By comparing the change of slab weight, rolling force...Spraying test were conducted twice before steel slabs were put into the furnace and the effects of the oxidation resistance coating were investigated and verified. By comparing the change of slab weight, rolling force of the roughing mill ＆ finishing mill, thickness of oxide film on the surface slabs by an XL-30 SEM and acid pickling speed of slabs with and without coating,it was found that the oxidization waste in the furnace decreased by 40 percent with the use of the coating and the corresponding yield capacity could increase by 0.2 percent at least. Besides, the thickness of oxide scale film on hot roiled products was reduced by 1.44 micrometers and the acid pickling time was shortened by 6s with the coating technology, while the total rolling force of RM ＆ FM did not changed. Furthermore, the application prospect of this technology was also discussed in this paper.展开更多
Rapid development has led to a tremendous increase in the volume of solid waste produced in rural China.The annual amount of solid waste produced from Chinese rural areas is approximately 110 million tons.Many small-s...Rapid development has led to a tremendous increase in the volume of solid waste produced in rural China.The annual amount of solid waste produced from Chinese rural areas is approximately 110 million tons.Many small-scale solid waste incinerators have been built in Chinese rural areas.It was speculated that the emissions and potential risks of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs,commonly known as dioxins)and polychlorinated naphthalenes(PCNs)from these incinerators could be serious.A preliminary case investigation on PCDD/F and PCN emissions from a small-scale waste incinerator was performed.The stack gas samples were collected using auto isokinetic sampling techniques and PCDD/F and PCN congeners were identified and quantified by high resolution gas chromatography combined with high resolution mass spectrometry.Concentrations and toxic equivalents of PCDD/Fs emitted from the small-scale waste incinerator were 153 ngm^-3 and 5.6 ng TEQ m^-3,respectively,which was much higher than the regulatory level for municipal solid waste incinerators permitted in China and the European Union Directive.PCNs have similar toxicological effects with PCDD/Fs,and the relative potency factors(RPFs)of some PCN congeners(dioxin-like PCNs)to 2,3,7,8-tetrachlorinated dibenzo-p-dioxin(TCDD)were previously proposed to evaluate the dioxin-like toxicity of PCNs.The mass concentrations of PCNs and dioxin-like PCNs from the small-scale solid incinerator were 2927 ngm^-3 and 1137 ngm^-3,much higher than that of dioxins.However,much less attention has been paid to the small-scale incinerators compared with municipal solid waste incinerators.Here,we proposed that there should be a growing need to focus on the emissions and potential risks of dioxins and dioxin-like pollutants from these small-scale waste incinerators in rural China.展开更多
In the production(as co-fuel or alone)of solid refuse fuel(SRF),knowledge about the characteristics of the raw materials is required for an ecofriendly and effective combustion process.SRFs are commonly produced by dr...In the production(as co-fuel or alone)of solid refuse fuel(SRF),knowledge about the characteristics of the raw materials is required for an ecofriendly and effective combustion process.SRFs are commonly produced by drying combustible waste and removing incombustible matter,resulting in a higher combustibility as compared to the original waste.However,the characteristics of SRFs may highly vary depending on where and from which materials they were produced.Thus,we investigated the characteristics of various SRFs using thermogravimetric analysis(TGA).As a TGA sample is commonly small,on the scale of milligrams,and,unlike homogeneous fuels,SRFs are heterogeneous,individual SRF samples analysed with this method may not represent the bulk material,and sample properties may vary significantly between batches.Therefore,we further performed combustion experiments using a small-scale combustor and sample sizes from 1 to 10 g.To optimise SRF combustor design and determine the SRF characteristics,proximate,elemental,heating value,TG,and differential thermogravimetric analyses were conducted,and weight losses and gas concentrations at different temperatures were measured upon combustion.The lower heating values of the three analysed SRFs were 20,976,16,873,and 19,762 kJ/kg,and their Cl contents were 0.89,0.95,and 1.27 wt.%(legal criterion[Cl]<2.0 wt.%).TGA and small combustor experiments showed that complete weight loss was achieved below 500°C.However,CO was detected until 620°C.展开更多
基金supported as part of the Center for Hierarchical Waste Form Materials,an Energy Frontier Research Center funded by the U.S.Department of Energy,Office of Science,Basic Energy Sciences under Award No.DE-SC0016574.
文摘Porous materials present significant advantages for absorbing radioactive isotopes in nuclear waste streams.To improve absorption efficiency in nuclear waste treatment,a thorough understanding of the diffusion-advection process within porous structures is essential for material design.In this study,we present advancements in the volumetric lattice Boltzmann method(VLBM)for modeling and simulating pore-scale diffusion-advection of radioactive isotopes within geopolymer porous structures.These structures are created using the phase field method(PFM)to precisely control pore architectures.In our VLBM approach,we introduce a concentration field of an isotope seamlessly coupled with the velocity field and solve it by the time evolution of its particle population function.To address the computational intensity inherent in the coupled lattice Boltzmann equations for velocity and concentration fields,we implement graphics processing unit(GPU)parallelization.Validation of the developed model involves examining the flow and diffusion fields in porous structures.Remarkably,good agreement is observed for both the velocity field from VLBM and multiphysics object-oriented simulation environment(MOOSE),and the concentration field from VLBM and the finite difference method(FDM).Furthermore,we investigate the effects of background flow,species diffusivity,and porosity on the diffusion-advection behavior by varying the background flow velocity,diffusion coefficient,and pore volume fraction,respectively.Notably,all three parameters exert an influence on the diffusion-advection process.Increased background flow and diffusivity markedly accelerate the process due to increased advection intensity and enhanced diffusion capability,respectively.Conversely,increasing the porosity has a less significant effect,causing a slight slowdown of the diffusion-advection process due to the expanded pore volume.This comprehensive parametric study provides valuable insights into the kinetics of isotope uptake in porous structures,facilitating the de
文摘Spraying test were conducted twice before steel slabs were put into the furnace and the effects of the oxidation resistance coating were investigated and verified. By comparing the change of slab weight, rolling force of the roughing mill ＆ finishing mill, thickness of oxide film on the surface slabs by an XL-30 SEM and acid pickling speed of slabs with and without coating,it was found that the oxidization waste in the furnace decreased by 40 percent with the use of the coating and the corresponding yield capacity could increase by 0.2 percent at least. Besides, the thickness of oxide scale film on hot roiled products was reduced by 1.44 micrometers and the acid pickling time was shortened by 6s with the coating technology, while the total rolling force of RM ＆ FM did not changed. Furthermore, the application prospect of this technology was also discussed in this paper.
基金We gratefully acknowledge support from the National 973 program(2015CB453100)the National Natural Science Foundation of China(21777172)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB14020102)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2016038).
文摘Rapid development has led to a tremendous increase in the volume of solid waste produced in rural China.The annual amount of solid waste produced from Chinese rural areas is approximately 110 million tons.Many small-scale solid waste incinerators have been built in Chinese rural areas.It was speculated that the emissions and potential risks of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs,commonly known as dioxins)and polychlorinated naphthalenes(PCNs)from these incinerators could be serious.A preliminary case investigation on PCDD/F and PCN emissions from a small-scale waste incinerator was performed.The stack gas samples were collected using auto isokinetic sampling techniques and PCDD/F and PCN congeners were identified and quantified by high resolution gas chromatography combined with high resolution mass spectrometry.Concentrations and toxic equivalents of PCDD/Fs emitted from the small-scale waste incinerator were 153 ngm^-3 and 5.6 ng TEQ m^-3,respectively,which was much higher than the regulatory level for municipal solid waste incinerators permitted in China and the European Union Directive.PCNs have similar toxicological effects with PCDD/Fs,and the relative potency factors(RPFs)of some PCN congeners(dioxin-like PCNs)to 2,3,7,8-tetrachlorinated dibenzo-p-dioxin(TCDD)were previously proposed to evaluate the dioxin-like toxicity of PCNs.The mass concentrations of PCNs and dioxin-like PCNs from the small-scale solid incinerator were 2927 ngm^-3 and 1137 ngm^-3,much higher than that of dioxins.However,much less attention has been paid to the small-scale incinerators compared with municipal solid waste incinerators.Here,we proposed that there should be a growing need to focus on the emissions and potential risks of dioxins and dioxin-like pollutants from these small-scale waste incinerators in rural China.
基金supported by the Korea Environment Industry&Technology Institute(KEITI)through a Public Technology Program based on the Environmental Policy Program funded by the Korea Ministry of Environment(MOE)[Grant number:2016000710008].
文摘In the production(as co-fuel or alone)of solid refuse fuel(SRF),knowledge about the characteristics of the raw materials is required for an ecofriendly and effective combustion process.SRFs are commonly produced by drying combustible waste and removing incombustible matter,resulting in a higher combustibility as compared to the original waste.However,the characteristics of SRFs may highly vary depending on where and from which materials they were produced.Thus,we investigated the characteristics of various SRFs using thermogravimetric analysis(TGA).As a TGA sample is commonly small,on the scale of milligrams,and,unlike homogeneous fuels,SRFs are heterogeneous,individual SRF samples analysed with this method may not represent the bulk material,and sample properties may vary significantly between batches.Therefore,we further performed combustion experiments using a small-scale combustor and sample sizes from 1 to 10 g.To optimise SRF combustor design and determine the SRF characteristics,proximate,elemental,heating value,TG,and differential thermogravimetric analyses were conducted,and weight losses and gas concentrations at different temperatures were measured upon combustion.The lower heating values of the three analysed SRFs were 20,976,16,873,and 19,762 kJ/kg,and their Cl contents were 0.89,0.95,and 1.27 wt.%(legal criterion[Cl]<2.0 wt.%).TGA and small combustor experiments showed that complete weight loss was achieved below 500°C.However,CO was detected until 620°C.
