Coal-fired power plants are considered a major source of fine particle emissions in China.Aimed to improve the removal efficiency of fine particles during the limestone-gypsum wet flue gas desulfurization(WFGD) proces...Coal-fired power plants are considered a major source of fine particle emissions in China.Aimed to improve the removal efficiency of fine particles during the limestone-gypsum wet flue gas desulfurization(WFGD) process, a novel technology using chemical agglomeration to abate the emission of fine particles is presented herein. The relationship between fine particle emission and the proportion of fine particles in the desulfurization slurry was studied.Additionally, the influence of chemical agglomeration on fine particle size distribution, both in the flue gas and slurry was experimentally investigated. When chemical agglomeration agents were added to the desulfurization slurry, the fine particle removal performance as well as the effects of the operation parameters was also explored via the simulated experimental facility.The results revealed that the fine particles in both the desulfurization slurry and flue gas were significantly enlarged after the addition of the agglomeration agents. This was more marked in the submicron particles. Thus, the proportion of fine particles(< 10 μm) in the slurry decreased from 31.1% to 22.6%. An increase in the desulfurization slurry temperature and liquid-to-gas ratio aided the reduction in fine particle emission. Moreover, the addition of an agglomeration agent in the slurry did not affect the desulfurization efficiency of the desulfurization tower and even promoted the WFGD process. Thus, the proposed chemical agglomeration technique reduced the fine particle emission of the WFGD system by ～30%, while a desulfurization efficiency >90% was maintained.展开更多
Selective catalytic reduction(SCR) denitration may increase the emission of NH4+and NH3.The removal and transformation characteristics of ammonium sulfate aerosols and ammonia slip during the wet flue gas desulfurizat...Selective catalytic reduction(SCR) denitration may increase the emission of NH4+and NH3.The removal and transformation characteristics of ammonium sulfate aerosols and ammonia slip during the wet flue gas desulfurization(WFGD) process, as well as the effect of desulfurization parameters, were investigated in an experimental system equipped with a simulated SCR flue gas generation system and a limestone-based WFGD system.The results indicate that the ammonium sulfate aerosols and ammonia slip in the flue gas from SCR can be partly removed by slurry scrubbing, while the entrainment and evaporation of desulfurization slurry with accumulated NH4+will generate new ammoniumcontaining particles and gaseous ammonia.The ammonium-containing particles formed by desulfurization are not only derived from the entrainment of slurry droplets, but also from the re-condensation of gaseous ammonia generated by slurry evaporation.Therefore,even if the concentration of NH4+in the desulfurization slurry is quite low, a high level of NH4+was still contained in the fine particles at the outlet of the scrubber.When the accumulated NH4+in the desulfurization slurry was high enough, the WFGD system promoted the conversion of NH3 to NH4+and increased the additional emission of primary NH4+aerosols.With the decline of the liquid/gas ratio and flue gas temperature, the removal efficiency of ammonia sulfate aerosols increased, and the NH4+emitted from entrainment and evaporation of the desulfurization slurry decreased.In addition, the volatile ammonia concentration after the WFGD system was reduced with the decrease of the NH4+concentration and p H values of the slurry.展开更多
Turbulent agglomeration is a promising pretreatment technology for improving the removal of fine particles in industrial flue gas,which can improve the particle removal effect of dust removal equipment safely and econ...Turbulent agglomeration is a promising pretreatment technology for improving the removal of fine particles in industrial flue gas,which can improve the particle removal effect of dust removal equipment safely and economically.However,due to the complexity of turbulence mechanisms,the relationship between turbulent flow fields and the agglomeration of fine particles is not known with precision,resulting a weak promotion effect for particle removal with this pretreatment technology.In this work,three kinds of turbulent agglomerators were constructed to investigate the agglomeration and removal characteristics of fine particles under different turbulent flow fields.The results demonstrated that the turbulent agglomerator with small-scale and three-dimensional vortexes in the flow field had the best effect in improving the agglomeration and removal of fine particles.Two kinds of agglomeration modes in turbulent agglomeration were proposed,one being agglomeration between fine particles in the vortex area,and the other the capture of fine particles by coarse particles.Furthermore,the motion trajectory,relative velocity and residence time of fine particles of different sizes in different flow fields were calculated by numerical simulation to investigate the interaction mechanism of particle agglomeration and turbulent flow fields.The results showed that a flow field with smallscale and three-dimensional vortexes can reduce the Stokes number(StK) and the relative velocity of particles of different sizes,and extend their residence time in a turbulent flow field,so as to obtain a better agglomeration effect for fine particles.展开更多
The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition beha...The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition behavior and SO2 poisoning over V2 O5-MoO3/TiO2 catalysts modified with CeO2 and SiO2 were investigated.By the means of characterization analysis,it was found that the addition of SiO2 into VMo/Ti-Ce had an impact on the interaction existed between catalyst surface atoms and NH4 HSO4.Temperatureprogrammed methods and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)experiments indicated that the doping of SiO2 promoted the decomposition of deposited NH4 HSO4 on VMo/Ti-Ce catalyst surface by reducing the thermal stability of NH4 HSO4 and enhancing the NH4 HSO4 reactivity with NO in low temperature.And this improvement may be the reason for the better catalytic activity than VMo/Ti-Ce in the case of NH4 HSO4 deposition.Accompanied with cerium sulfate species generated over catalyst surface,the conversion of SO2 to SO3 was inhibited in SiCe mixed catalyst.The addition of SiO2 could promote the decomposition of cerium sulfate,which may be a potential strategy to enhance the resistance of SO2 poisoning over CeO2-modifed catalysts.展开更多
Particulate matter emissions from ammonia-based wet flue gas desulfurization(AmmoniaWFGD)systems are composed of a filterable particulate matter and a condensable particulate matter(CPM)portion.However,the CPM part ha...Particulate matter emissions from ammonia-based wet flue gas desulfurization(AmmoniaWFGD)systems are composed of a filterable particulate matter and a condensable particulate matter(CPM)portion.However,the CPM part has been ignored for a long time,which results in an underestim ation of the aerosol problems caused by Ammonia-WFGD systems.In our research,the characteristics of the CPM that emits from an Ammonia-WFGD system are investigated experimentally for the first time,with the US Environmental Protection Agency Method 202 employed as the primary measurement.The influences of some essential desulfurizing parameters are evaluated based on the experimental data.The results show that CPM contributes about 68.8%to the total particulate matter emission.CPM consists mainly of ammonium sulfates/sulfites,with the organic part accounting for less than 4%.CPM is mostly in the submicron fraction,about 71.1%of which originates from the NH3-H2O-SO2 reactions.The appropriate adjustments for the parameters of the flue gas and the desulfurizing solution can inhibit CPM formation to different extents.This indicates that the parameter optimizations are promising in solving CPM emission problems in Ammonia-WFGD systems,in which the pH adjustment alone can abate CPM emission by around 49%.The opposite variations of the parameters need attention because they can cause tremendous CPM emission increase.展开更多
The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent（MBS） for COcapture consisting of polyethylenimine and one of the foll...The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent（MBS） for COcapture consisting of polyethylenimine and one of the following supports: SBA-15（2-D structure）, TUD-1（3-D sponge-like structure） and fumed silica HS-5（3-D disordered structure）. Effects of the supports regarding pore structures and pore properties, the PEI loading amount as well as the sorption temperature were examined. Furthermore, polyethylene glycol（PEG） was introduced as an additive into the sorbents and its effect was investigated at different PEI loadings and sorption temperatures. The results suggest that the pore properties of MBS（after PEI loading） play a more important role in the COsorption capacity, rather than those of the supports alone.MBS with 3D pore structure exhibits higher COsorption capacity and amine efficiency than those with 2D-structured support. Among the sorbents studied, fumed silica（HS-5） based MBS showed the highest COsorption capacity in the temperature range of 30-95 °C, probably due to its unique interstitial pores formed by the aggregation of polymer-loaded SiOparticles. It was found that the temperature dependence is directly related to the PEI surface coverage layers. The more PEI surface coverage layers, the higher diffusion barrier for COand the stronger temperature dependence of COcapacity. 3D MBS exceeds 2D MBS at the same PEI coverage layers due to lower diffusion barrier. Adding PEG can significantly enhance the COsorption capacity and improve amine efficiency of all MBS, most likely by alleviating the diffusion barrier within PEI bulk layers through the inter-molecular interaction between PEI and PEG.展开更多
The relationship between the fine particles emitted after desulfurization and gypsum crystals in the desulfurization slurry was investigated,and the crystallization characteristics varying with the operation parameter...The relationship between the fine particles emitted after desulfurization and gypsum crystals in the desulfurization slurry was investigated,and the crystallization characteristics varying with the operation parameters and compositions of the desulfurization slurry were discussed.The results showed that the fine particles generated during the desulfurization process were closely related to the crystal characteristics in the desulfurization slurry by comparison of their morphology and elements. With the higher proportion of fine crystals in the desulfurization slurry,the number concentration of fine particles after desulfurization was increased and their particle sizes were smaller,indicating that the optimization of gypsum crystallization was beneficial for the reduction of the fine particle emission. The lower p H value and an optimal temperature of the desulfurization slurry were beneficial to restrain the generation of fine crystals in the desulfurization slurry. In addition,the higher concentrations of the Fe3＋ions and the F- ions in the desulfurization slurry both promoted the generation of fine crystals with corresponding change of the morphology and the effect of the Fe3＋ ions was more obvious.With the application of the desulfurization synergist additive,it was beneficial for the inhibition of fine crystals while the thinner crystals were generated.展开更多
Inflammatory responses of nucleus pulposus(NP)can induce imbalanced anabolism and catabolism of extracellular matrix,and the cytosolic dsDNA accumulation and STING-NF-κB pathway activation found in NP inflammation ar...Inflammatory responses of nucleus pulposus(NP)can induce imbalanced anabolism and catabolism of extracellular matrix,and the cytosolic dsDNA accumulation and STING-NF-κB pathway activation found in NP inflammation are considered as fairly important cause of intervertebral disc(IVD)degeneration.Herein,we constructed a siSTING delivery hydrogel of aldehyde hyaluronic acid(HA-CHO)and poly(amidoamine)PAMAM/siRNA complex to intervene the abnormal STING signal for IVD degeneration treatment,where the formation of dynamic Schiff base bonds in the system(siSTING@HPgel)was able to overcome the shortcomings such as low cellular uptake,short half-life,and rapid degradation of siRNA-based strategy.PAMAM not only formed complexes with siRNA to promote siRNA transfection,but also served as dynamic crosslinker to construct hydrogel,and the injectable and self-healing hydrogel efficiently and steadily silenced STING expression in NP cells.Finally,the siSTING@HPgel significantly eased IVD inflammation and slowed IVD degeneration by prolonging STING knockdown in puncture-induced IVD degeneration rat model,revealing that STING pathway was a therapeutic target for IVD degeneration and such novel hydrogel had great potential for being applied to many other diseases for gene delivery.展开更多
基金supported by the National Key Research and Development Program of China (No. 2016YFB0600602)
文摘Coal-fired power plants are considered a major source of fine particle emissions in China.Aimed to improve the removal efficiency of fine particles during the limestone-gypsum wet flue gas desulfurization(WFGD) process, a novel technology using chemical agglomeration to abate the emission of fine particles is presented herein. The relationship between fine particle emission and the proportion of fine particles in the desulfurization slurry was studied.Additionally, the influence of chemical agglomeration on fine particle size distribution, both in the flue gas and slurry was experimentally investigated. When chemical agglomeration agents were added to the desulfurization slurry, the fine particle removal performance as well as the effects of the operation parameters was also explored via the simulated experimental facility.The results revealed that the fine particles in both the desulfurization slurry and flue gas were significantly enlarged after the addition of the agglomeration agents. This was more marked in the submicron particles. Thus, the proportion of fine particles(< 10 μm) in the slurry decreased from 31.1% to 22.6%. An increase in the desulfurization slurry temperature and liquid-to-gas ratio aided the reduction in fine particle emission. Moreover, the addition of an agglomeration agent in the slurry did not affect the desulfurization efficiency of the desulfurization tower and even promoted the WFGD process. Thus, the proposed chemical agglomeration technique reduced the fine particle emission of the WFGD system by ～30%, while a desulfurization efficiency >90% was maintained.
基金supported by the National Natural Science Foundation of China(Nos.51576039 and 51576039).
文摘Selective catalytic reduction(SCR) denitration may increase the emission of NH4+and NH3.The removal and transformation characteristics of ammonium sulfate aerosols and ammonia slip during the wet flue gas desulfurization(WFGD) process, as well as the effect of desulfurization parameters, were investigated in an experimental system equipped with a simulated SCR flue gas generation system and a limestone-based WFGD system.The results indicate that the ammonium sulfate aerosols and ammonia slip in the flue gas from SCR can be partly removed by slurry scrubbing, while the entrainment and evaporation of desulfurization slurry with accumulated NH4+will generate new ammoniumcontaining particles and gaseous ammonia.The ammonium-containing particles formed by desulfurization are not only derived from the entrainment of slurry droplets, but also from the re-condensation of gaseous ammonia generated by slurry evaporation.Therefore,even if the concentration of NH4+in the desulfurization slurry is quite low, a high level of NH4+was still contained in the fine particles at the outlet of the scrubber.When the accumulated NH4+in the desulfurization slurry was high enough, the WFGD system promoted the conversion of NH3 to NH4+and increased the additional emission of primary NH4+aerosols.With the decline of the liquid/gas ratio and flue gas temperature, the removal efficiency of ammonia sulfate aerosols increased, and the NH4+emitted from entrainment and evaporation of the desulfurization slurry decreased.In addition, the volatile ammonia concentration after the WFGD system was reduced with the decrease of the NH4+concentration and p H values of the slurry.
基金supported by the National Key Research and Development Program of China (No.2016YFB0600602)the National Natural Science Foundation of China (No.51806107)the Scientific Research Foundation of Graduate School of Southeast University (No.3203009749).
文摘Turbulent agglomeration is a promising pretreatment technology for improving the removal of fine particles in industrial flue gas,which can improve the particle removal effect of dust removal equipment safely and economically.However,due to the complexity of turbulence mechanisms,the relationship between turbulent flow fields and the agglomeration of fine particles is not known with precision,resulting a weak promotion effect for particle removal with this pretreatment technology.In this work,three kinds of turbulent agglomerators were constructed to investigate the agglomeration and removal characteristics of fine particles under different turbulent flow fields.The results demonstrated that the turbulent agglomerator with small-scale and three-dimensional vortexes in the flow field had the best effect in improving the agglomeration and removal of fine particles.Two kinds of agglomeration modes in turbulent agglomeration were proposed,one being agglomeration between fine particles in the vortex area,and the other the capture of fine particles by coarse particles.Furthermore,the motion trajectory,relative velocity and residence time of fine particles of different sizes in different flow fields were calculated by numerical simulation to investigate the interaction mechanism of particle agglomeration and turbulent flow fields.The results showed that a flow field with smallscale and three-dimensional vortexes can reduce the Stokes number(StK) and the relative velocity of particles of different sizes,and extend their residence time in a turbulent flow field,so as to obtain a better agglomeration effect for fine particles.
基金supported by the National Natural Science Foundation of China(No.51576039)
文摘The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition behavior and SO2 poisoning over V2 O5-MoO3/TiO2 catalysts modified with CeO2 and SiO2 were investigated.By the means of characterization analysis,it was found that the addition of SiO2 into VMo/Ti-Ce had an impact on the interaction existed between catalyst surface atoms and NH4 HSO4.Temperatureprogrammed methods and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)experiments indicated that the doping of SiO2 promoted the decomposition of deposited NH4 HSO4 on VMo/Ti-Ce catalyst surface by reducing the thermal stability of NH4 HSO4 and enhancing the NH4 HSO4 reactivity with NO in low temperature.And this improvement may be the reason for the better catalytic activity than VMo/Ti-Ce in the case of NH4 HSO4 deposition.Accompanied with cerium sulfate species generated over catalyst surface,the conversion of SO2 to SO3 was inhibited in SiCe mixed catalyst.The addition of SiO2 could promote the decomposition of cerium sulfate,which may be a potential strategy to enhance the resistance of SO2 poisoning over CeO2-modifed catalysts.
基金supported by the National Key Research and Development Program of China(No.2016YFC0203703)the National Natural Science Foundation of China(Nos.51576039,51806107 and 21276049)+1 种基金the Scientific Research Foundation of Graduate School of Southeast University(No.YBJJ1610)the Research Innovation Program for College Graduates of Jiangsu Province(No.KYLX16_0283)。
文摘Particulate matter emissions from ammonia-based wet flue gas desulfurization(AmmoniaWFGD)systems are composed of a filterable particulate matter and a condensable particulate matter(CPM)portion.However,the CPM part has been ignored for a long time,which results in an underestim ation of the aerosol problems caused by Ammonia-WFGD systems.In our research,the characteristics of the CPM that emits from an Ammonia-WFGD system are investigated experimentally for the first time,with the US Environmental Protection Agency Method 202 employed as the primary measurement.The influences of some essential desulfurizing parameters are evaluated based on the experimental data.The results show that CPM contributes about 68.8%to the total particulate matter emission.CPM consists mainly of ammonium sulfates/sulfites,with the organic part accounting for less than 4%.CPM is mostly in the submicron fraction,about 71.1%of which originates from the NH3-H2O-SO2 reactions.The appropriate adjustments for the parameters of the flue gas and the desulfurizing solution can inhibit CPM formation to different extents.This indicates that the parameter optimizations are promising in solving CPM emission problems in Ammonia-WFGD systems,in which the pH adjustment alone can abate CPM emission by around 49%.The opposite variations of the parameters need attention because they can cause tremendous CPM emission increase.
基金the support of this work at Penn State by the U.S.Department of Energy,National Energy Technology Laboratorythe financial support by the China Scholarship Council,the Natural Science Foundation of China(No.51176034)the Open Fund of Key Laboratory of Coal-Based CO2 Capture and Geological Storage of Jiangsu Province(2016A05)
文摘The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent（MBS） for COcapture consisting of polyethylenimine and one of the following supports: SBA-15（2-D structure）, TUD-1（3-D sponge-like structure） and fumed silica HS-5（3-D disordered structure）. Effects of the supports regarding pore structures and pore properties, the PEI loading amount as well as the sorption temperature were examined. Furthermore, polyethylene glycol（PEG） was introduced as an additive into the sorbents and its effect was investigated at different PEI loadings and sorption temperatures. The results suggest that the pore properties of MBS（after PEI loading） play a more important role in the COsorption capacity, rather than those of the supports alone.MBS with 3D pore structure exhibits higher COsorption capacity and amine efficiency than those with 2D-structured support. Among the sorbents studied, fumed silica（HS-5） based MBS showed the highest COsorption capacity in the temperature range of 30-95 °C, probably due to its unique interstitial pores formed by the aggregation of polymer-loaded SiOparticles. It was found that the temperature dependence is directly related to the PEI surface coverage layers. The more PEI surface coverage layers, the higher diffusion barrier for COand the stronger temperature dependence of COcapacity. 3D MBS exceeds 2D MBS at the same PEI coverage layers due to lower diffusion barrier. Adding PEG can significantly enhance the COsorption capacity and improve amine efficiency of all MBS, most likely by alleviating the diffusion barrier within PEI bulk layers through the inter-molecular interaction between PEI and PEG.
基金supported by the National Natural Science Foundation of China(No.21276049)the National Basic Research Program of China(973 Program)(No.2013CB228505)the Science and Technology Support Program of Jiangsu(No.BE2014856) for their financial support
文摘The relationship between the fine particles emitted after desulfurization and gypsum crystals in the desulfurization slurry was investigated,and the crystallization characteristics varying with the operation parameters and compositions of the desulfurization slurry were discussed.The results showed that the fine particles generated during the desulfurization process were closely related to the crystal characteristics in the desulfurization slurry by comparison of their morphology and elements. With the higher proportion of fine crystals in the desulfurization slurry,the number concentration of fine particles after desulfurization was increased and their particle sizes were smaller,indicating that the optimization of gypsum crystallization was beneficial for the reduction of the fine particle emission. The lower p H value and an optimal temperature of the desulfurization slurry were beneficial to restrain the generation of fine crystals in the desulfurization slurry. In addition,the higher concentrations of the Fe3＋ions and the F- ions in the desulfurization slurry both promoted the generation of fine crystals with corresponding change of the morphology and the effect of the Fe3＋ ions was more obvious.With the application of the desulfurization synergist additive,it was beneficial for the inhibition of fine crystals while the thinner crystals were generated.
基金The study was sponsored by National Natural Science Foundation of China(81672150,51903050)Zhejiang medical and health science and technology project(2018KY117,2019ZD041)+1 种基金Natural Science Foundation of Zhejiang Province of China(LQ20H160053)New talent in medical field of Zhejiang Province,and the fundamental research funds for the central universities(2019QNA7027).
文摘Inflammatory responses of nucleus pulposus(NP)can induce imbalanced anabolism and catabolism of extracellular matrix,and the cytosolic dsDNA accumulation and STING-NF-κB pathway activation found in NP inflammation are considered as fairly important cause of intervertebral disc(IVD)degeneration.Herein,we constructed a siSTING delivery hydrogel of aldehyde hyaluronic acid(HA-CHO)and poly(amidoamine)PAMAM/siRNA complex to intervene the abnormal STING signal for IVD degeneration treatment,where the formation of dynamic Schiff base bonds in the system(siSTING@HPgel)was able to overcome the shortcomings such as low cellular uptake,short half-life,and rapid degradation of siRNA-based strategy.PAMAM not only formed complexes with siRNA to promote siRNA transfection,but also served as dynamic crosslinker to construct hydrogel,and the injectable and self-healing hydrogel efficiently and steadily silenced STING expression in NP cells.Finally,the siSTING@HPgel significantly eased IVD inflammation and slowed IVD degeneration by prolonging STING knockdown in puncture-induced IVD degeneration rat model,revealing that STING pathway was a therapeutic target for IVD degeneration and such novel hydrogel had great potential for being applied to many other diseases for gene delivery.
