The addition of dispersed-phase nanoparticles in the liquid phase can enhance the gas-liquid transfer process as the suspended nanoparticles affect the transfer process inside the fluid through microdisturbance or mic...The addition of dispersed-phase nanoparticles in the liquid phase can enhance the gas-liquid transfer process as the suspended nanoparticles affect the transfer process inside the fluid through microdisturbance or micro-convection effects.In this article,a high-speed digital camera was used to visualize the bubble behavior of CO_(2) in pure water and nanofluids to examine the effects of CO_(2) gas flow rate,nanoparticle solid content and type on the bubble behavior in the fluids.The CO_(2) absorption performance in three water-based nanofluids were compared in a bubbler.And the mass transfer characteristics during CO_(2) bubble absorption and the reasons for the enhanced gas-liquid mass transfer effect of nanoparticles were analyzed.The results showed that the presence of nanoparticles affected the formation process of bubbles in the fluid,shortened the bubble detachment time,reduced the detachment diameter,effectively increased the gas-liquid contact area,and improved the bubbles detachment frequency.The system with MCM-41 corresponded to a higher overall mass transfer coefficient.Uncalined MCM-41 contained surfactant that enhanced foaming behavior in water.This prevented the transfer of CO_(2) to some extent,and the CO_(2) absorption by uncalined MCM-41/H_(2)O was 5.34%higher than that by pure water.Compared with SiO_(2) nanoparticles with the same particle size and the same composition,MCM-41 had a higher adsorption capacity and better hydrophilicity due to its larger specific surface area and rich porous structure,which was more favorable to accelerate the collision between nanoparticles and CO_(2) bubbles to cause micro-convection.Under the condition of 0.1%(mass)solid content,the enhancement of CO_(2) absorption process by MCM-41 nanoparticles was more significant and improved by 16.9%compared with pure water.展开更多
The traditional gas purification techniques such as wet gas desulfurization, with their advantages of large-scale implementation and maturity, have still been widely used. However, the main drawback of these technique...The traditional gas purification techniques such as wet gas desulfurization, with their advantages of large-scale implementation and maturity, have still been widely used. However, the main drawback of these techniques is the low transfer efficiency, which normally needs towers as tall as tens of meters to remove the pollutants. Therefore, new technologies which could enhance the mass transfer efficiency and are less energy-intensive are highly desirable. As a process intensification technology, high-gravity technology, which is carried out in a rotating packed bed(RPB), has recently demonstrated great potential for industrial applications due to its high mass transfer efficiency, energy-saving, and smaller volume. This consequently provides higher efficiency in toxic gas removal, and can significantly reduce the investment and operation costs. In this review, the mechanism,characteristics, recent developments, and the industry applications of high-gravity technologies in gas purifications, such as hydrogen sulfide, nitrogen oxide, carbon dioxide, sulfur dioxide, volatile organic compounds and nanoparticle removal are discussed, most of the demonstration projects and practical application examples in gas purification come from China. The perspective and prospective of this technology in gas purification and other fields are also briefly discussed.展开更多
The rotating packed bed （RPB） with split packing is a novel gas-liquid contactor, which intensifies the mass transfer processes controlled by gas-side resistance. To assess its efficacy, the mass transfer characteri...The rotating packed bed （RPB） with split packing is a novel gas-liquid contactor, which intensifies the mass transfer processes controlled by gas-side resistance. To assess its efficacy, the mass transfer characteristics with adjacent rings in counter-rotation and co-rotation modes in a split packing RPB were studied experimentally. The physical absorption system NH3-H2O was used for characterizing the gas volumetric mass transfer coeffi- cient （kyae） and the effective inteffacial area （ae） was determined by chemical absorption in the CO2-NaOH sys- tem. The variation in kyae and ae with the operating conditions is also investigated. The experimental results indicated that kyae and ae for counter-rotation of the adjacent packing rings in the split packing RPB were higher than those for co-rotation, and both counter-rotation and co-rotation of the split packing RPB were superior over conventional RPBs under the similar ooerating conditions.展开更多
In this study,the fluid flow and mixing process in an impinging stream-rotating packed bed(IS-RPB)is simulated by using a new three-dimensional computational fluid dynamics model.Specifically,the gaseliquid flow is si...In this study,the fluid flow and mixing process in an impinging stream-rotating packed bed(IS-RPB)is simulated by using a new three-dimensional computational fluid dynamics model.Specifically,the gaseliquid flow is simulated by the Euler-Euler model,the hydrodynamics of the reactor is predicted by the RNG k-εmethod,and the high-gravity environment is simulated by the sliding mesh model.The turbulent mass transfer process is characterized by the concentration variance c^(2) and its dissipation rateεc formulations,and therefore the turbulent mass diffusivity can be directly obtained.The simulated segregation index Xs is in agreement with our previous experimental results.The simulated results reveal that the fringe effect of IS can be offset by the end effect at the inner radius of RPB,so the investigation of the coupling mechanism between IS and RPB is critical to intensify the mixing process in IS-RPB.展开更多
Nitric oxide being a major gas pollutant has attracted much attention and various technologies have been developed to reduce NO emission to preserve the environment.Advanced persulfate oxidation technology is a workab...Nitric oxide being a major gas pollutant has attracted much attention and various technologies have been developed to reduce NO emission to preserve the environment.Advanced persulfate oxidation technology is a workable and effective choice for wet flue gas denitrification due to its high efficiency and green advantages.However,NO absorption rate is limited and affected by mass transfer limitation of NO and aqueous persulfate in traditional reactors.In this study,a rotating packed bed(RPB)was employed as a gas-liquid absorption device to elevate the NO removal efficiency(η_(NO))by aqueous persulfate((NH_(4))_(2)S_(2)O_(8))activated by ferrous ethylenediaminetetraacetate(Fe^(^(2+))-EDTA).The experimental results regarding the NO absorption were obtained by investigating the effect of various operating parameters on the removal efficiency of NO in RPB.Increasing the concentration of(NH_(4))_(2)S_(2)O_(8) and liquid-gas ratio could promoted the oxidation and absorption of NO while theη_(NO) decreased with the increase of the gas flow and NO concentration.In addition,improving the high gravity factor increased theη_(NO) and the total volumetric mass transfer coefficient(K_(G)α )which raise theη_(NO) up to more than 75%under the investigated system.These observations proved that the RPB can enhance the gas-liquid mass transfer process in NO absorption.The correlation formula between K_(G)α and the influencing factors was determined by regression calculation,which is used to guide the industrial scale-up application of the system in NO removal.The presence of O_(2) also had a negative effect on the NO removal process and through electron spin resonance spectrometer detection and product analysis,it was revealed that Fe^(2+)-EDTA activated(NH_(4))2S_(2)O_(8) to produce•SO_(4)^(-),•OH and•O_(2)^(-),played a leading role in the oxidation of NO,to produce NO_(3)^(-)as the final product.The obtained results demonstrated a good applicable potential of RPB/PS/Fe^(2+)-EDTA in the removal of NO from flue gases.展开更多
基金financial support from National Natural Science Foundation of China(22108263)Shanxi Province Basic Research Program Project(20210302124060)the 18th Graduate Student Technology Project of North University of China(20221824).
文摘The addition of dispersed-phase nanoparticles in the liquid phase can enhance the gas-liquid transfer process as the suspended nanoparticles affect the transfer process inside the fluid through microdisturbance or micro-convection effects.In this article,a high-speed digital camera was used to visualize the bubble behavior of CO_(2) in pure water and nanofluids to examine the effects of CO_(2) gas flow rate,nanoparticle solid content and type on the bubble behavior in the fluids.The CO_(2) absorption performance in three water-based nanofluids were compared in a bubbler.And the mass transfer characteristics during CO_(2) bubble absorption and the reasons for the enhanced gas-liquid mass transfer effect of nanoparticles were analyzed.The results showed that the presence of nanoparticles affected the formation process of bubbles in the fluid,shortened the bubble detachment time,reduced the detachment diameter,effectively increased the gas-liquid contact area,and improved the bubbles detachment frequency.The system with MCM-41 corresponded to a higher overall mass transfer coefficient.Uncalined MCM-41 contained surfactant that enhanced foaming behavior in water.This prevented the transfer of CO_(2) to some extent,and the CO_(2) absorption by uncalined MCM-41/H_(2)O was 5.34%higher than that by pure water.Compared with SiO_(2) nanoparticles with the same particle size and the same composition,MCM-41 had a higher adsorption capacity and better hydrophilicity due to its larger specific surface area and rich porous structure,which was more favorable to accelerate the collision between nanoparticles and CO_(2) bubbles to cause micro-convection.Under the condition of 0.1%(mass)solid content,the enhancement of CO_(2) absorption process by MCM-41 nanoparticles was more significant and improved by 16.9%compared with pure water.
基金Supported by the National Natural Science Foundation of China(U1610106)Shanxi Excellent Talent Science and Technology Innovation Project(201705D211011)+1 种基金Specialized Research Fund for Sanjin Scholars Program of Shanxi Province(201707)North University of China Fund for Distinguished Young Scholars(201701)
文摘The traditional gas purification techniques such as wet gas desulfurization, with their advantages of large-scale implementation and maturity, have still been widely used. However, the main drawback of these techniques is the low transfer efficiency, which normally needs towers as tall as tens of meters to remove the pollutants. Therefore, new technologies which could enhance the mass transfer efficiency and are less energy-intensive are highly desirable. As a process intensification technology, high-gravity technology, which is carried out in a rotating packed bed(RPB), has recently demonstrated great potential for industrial applications due to its high mass transfer efficiency, energy-saving, and smaller volume. This consequently provides higher efficiency in toxic gas removal, and can significantly reduce the investment and operation costs. In this review, the mechanism,characteristics, recent developments, and the industry applications of high-gravity technologies in gas purifications, such as hydrogen sulfide, nitrogen oxide, carbon dioxide, sulfur dioxide, volatile organic compounds and nanoparticle removal are discussed, most of the demonstration projects and practical application examples in gas purification come from China. The perspective and prospective of this technology in gas purification and other fields are also briefly discussed.
基金the National Natural Science Foundation of China(21376229,21206153)
文摘The rotating packed bed （RPB） with split packing is a novel gas-liquid contactor, which intensifies the mass transfer processes controlled by gas-side resistance. To assess its efficacy, the mass transfer characteristics with adjacent rings in counter-rotation and co-rotation modes in a split packing RPB were studied experimentally. The physical absorption system NH3-H2O was used for characterizing the gas volumetric mass transfer coeffi- cient （kyae） and the effective inteffacial area （ae） was determined by chemical absorption in the CO2-NaOH sys- tem. The variation in kyae and ae with the operating conditions is also investigated. The experimental results indicated that kyae and ae for counter-rotation of the adjacent packing rings in the split packing RPB were higher than those for co-rotation, and both counter-rotation and co-rotation of the split packing RPB were superior over conventional RPBs under the similar ooerating conditions.
基金supported by the National Natural Science Foundation of China (22208328, 22378370 and 22108261)Fundamental Research Program of Shanxi Province(20210302124618)
文摘In this study,the fluid flow and mixing process in an impinging stream-rotating packed bed(IS-RPB)is simulated by using a new three-dimensional computational fluid dynamics model.Specifically,the gaseliquid flow is simulated by the Euler-Euler model,the hydrodynamics of the reactor is predicted by the RNG k-εmethod,and the high-gravity environment is simulated by the sliding mesh model.The turbulent mass transfer process is characterized by the concentration variance c^(2) and its dissipation rateεc formulations,and therefore the turbulent mass diffusivity can be directly obtained.The simulated segregation index Xs is in agreement with our previous experimental results.The simulated results reveal that the fringe effect of IS can be offset by the end effect at the inner radius of RPB,so the investigation of the coupling mechanism between IS and RPB is critical to intensify the mixing process in IS-RPB.
基金the National Natural Science Foundation of China International (Regional)Cooperation and Exchange Project (Grant No.21961160740)the Shanxi Province Applied Basic Research Program (Grant No.201901D111178)2021 Shanxi Postgraduate Innovation Project (Grant No.2021Y601).
文摘Nitric oxide being a major gas pollutant has attracted much attention and various technologies have been developed to reduce NO emission to preserve the environment.Advanced persulfate oxidation technology is a workable and effective choice for wet flue gas denitrification due to its high efficiency and green advantages.However,NO absorption rate is limited and affected by mass transfer limitation of NO and aqueous persulfate in traditional reactors.In this study,a rotating packed bed(RPB)was employed as a gas-liquid absorption device to elevate the NO removal efficiency(η_(NO))by aqueous persulfate((NH_(4))_(2)S_(2)O_(8))activated by ferrous ethylenediaminetetraacetate(Fe^(^(2+))-EDTA).The experimental results regarding the NO absorption were obtained by investigating the effect of various operating parameters on the removal efficiency of NO in RPB.Increasing the concentration of(NH_(4))_(2)S_(2)O_(8) and liquid-gas ratio could promoted the oxidation and absorption of NO while theη_(NO) decreased with the increase of the gas flow and NO concentration.In addition,improving the high gravity factor increased theη_(NO) and the total volumetric mass transfer coefficient(K_(G)α )which raise theη_(NO) up to more than 75%under the investigated system.These observations proved that the RPB can enhance the gas-liquid mass transfer process in NO absorption.The correlation formula between K_(G)α and the influencing factors was determined by regression calculation,which is used to guide the industrial scale-up application of the system in NO removal.The presence of O_(2) also had a negative effect on the NO removal process and through electron spin resonance spectrometer detection and product analysis,it was revealed that Fe^(2+)-EDTA activated(NH_(4))2S_(2)O_(8) to produce•SO_(4)^(-),•OH and•O_(2)^(-),played a leading role in the oxidation of NO,to produce NO_(3)^(-)as the final product.The obtained results demonstrated a good applicable potential of RPB/PS/Fe^(2+)-EDTA in the removal of NO from flue gases.
