Fluidized beds enable good solids mixing,high rates of heat and mass transfer,and large throughputs,but there remain issues related to fluidization quality and scale-up.In this work I review modification techniques fo...Fluidized beds enable good solids mixing,high rates of heat and mass transfer,and large throughputs,but there remain issues related to fluidization quality and scale-up.In this work I review modification techniques for fluidized beds from the perspective of the principles of process intensification(PI),that is,effective bubbling suppression and elutriation control.These techniques are further refined into(1)design factors,e.g.modifying the bed configuration,or the application of internal and external forces,and(2)operational factors,including altering the particle properties(e.g.size,density,surface area)and fluidizing gas properties(e.g.density,viscosity,or velocity).As far as two proposed PI principles are concerned,our review suggests that it ought to be possible to gain improvements of between 2 and 4 times over conventional fluidized bed designs by the application of these techniques.展开更多
[ Objectlve] The research aimed to study treatment effect of the pesticide wastewater by the composite process of biological active car- bon filter-fluid bed. [Method] The composite process of biological active carbon...[ Objectlve] The research aimed to study treatment effect of the pesticide wastewater by the composite process of biological active car- bon filter-fluid bed. [Method] The composite process of biological active carbon filter- fluid bed was applied to treat the mixed pesticide wastewater. The removal efficiencies of CODcr, BODs, NH3-N, SS and the influence factors were investigated. [ Result] The composite process had good treatment efficiency for pesticide wastewater. After running stably, the average removal rates of CODc,, BODs, NH3-N and SS were re- spectively 91.6%, 96.2%, 90.2% and 87.5%. All indices reached the third level cdteda specified in Comprehensive Standard of the Sewage Dis- charge （DB12/356-2008）. [ Conclusionl The whole system operates reliably and simply, and provides a stable, convenient and economical solu- tion for deep treatment of the mixed pesticide wastewater.展开更多
In this study the effect of initial parameters such as inlet gas temperature, initial particles temperature and gas velocity on temperature changes of solid particles and outlet gas temperature in a fluidized bed drye...In this study the effect of initial parameters such as inlet gas temperature, initial particles temperature and gas velocity on temperature changes of solid particles and outlet gas temperature in a fluidized bed dryer was studied. For testing, an experimental setup was established. With combination of air and Colza seeds belonging to D groups of the Geldart classification (Geldart, 1986) fluidization regime was carried out. With five test series with maintaining the inlet gas temperature, solid particle temperature and outlet gas temperature during time were carefully measured. To analyze these data by using regression analysis to predict solid particle and outlet gas temperature, 2 correlations on initial pa-rameters were presented. The result has shown that temperature gradients in the beginning of fluidization, is very high and therefore the exponential functions in the regression model is used to predict the temperature changes.展开更多
A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and...A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.展开更多
In order to research the changing process of the pollution from the formation of Nansihu Lake, this study determined the isotope age and depositional rate and analyzed the organic geo-chem...In order to research the changing process of the pollution from the formation of Nansihu Lake, this study determined the isotope age and depositional rate and analyzed the organic geo-chemical quotas and heavy metal quotas of two sedimentary profiles of Weishan and Dushan lakes. Research results showed that from the formation of Nansihu Lake, the change of the pollution could be divided into four phrases. At the early phrase of the formation, the organic matters of the lake mainly derived from the exotic matters and had a close relation to the effect on the water and sands from the Huanghe (Yellow) River. At the middle and late phrases of the development, the endogenous matters of the lake became the main and stable source of the organic matters. The overflow of the Huanghe River, the excavation of the Grand Canal and the cut of trees caused the changes of the historic pollution. In recent 20 years, the modern industrial pollution from the organic matters and heavy metals has an increasingly heavy tendency.展开更多
文摘Fluidized beds enable good solids mixing,high rates of heat and mass transfer,and large throughputs,but there remain issues related to fluidization quality and scale-up.In this work I review modification techniques for fluidized beds from the perspective of the principles of process intensification(PI),that is,effective bubbling suppression and elutriation control.These techniques are further refined into(1)design factors,e.g.modifying the bed configuration,or the application of internal and external forces,and(2)operational factors,including altering the particle properties(e.g.size,density,surface area)and fluidizing gas properties(e.g.density,viscosity,or velocity).As far as two proposed PI principles are concerned,our review suggests that it ought to be possible to gain improvements of between 2 and 4 times over conventional fluidized bed designs by the application of these techniques.
基金Supported by Science Technology Key Special Item of the National Water Pollution Control and Treatment,China(2008ZX07314001)
文摘[ Objectlve] The research aimed to study treatment effect of the pesticide wastewater by the composite process of biological active car- bon filter-fluid bed. [Method] The composite process of biological active carbon filter- fluid bed was applied to treat the mixed pesticide wastewater. The removal efficiencies of CODcr, BODs, NH3-N, SS and the influence factors were investigated. [ Result] The composite process had good treatment efficiency for pesticide wastewater. After running stably, the average removal rates of CODc,, BODs, NH3-N and SS were re- spectively 91.6%, 96.2%, 90.2% and 87.5%. All indices reached the third level cdteda specified in Comprehensive Standard of the Sewage Dis- charge （DB12/356-2008）. [ Conclusionl The whole system operates reliably and simply, and provides a stable, convenient and economical solu- tion for deep treatment of the mixed pesticide wastewater.
文摘In this study the effect of initial parameters such as inlet gas temperature, initial particles temperature and gas velocity on temperature changes of solid particles and outlet gas temperature in a fluidized bed dryer was studied. For testing, an experimental setup was established. With combination of air and Colza seeds belonging to D groups of the Geldart classification (Geldart, 1986) fluidization regime was carried out. With five test series with maintaining the inlet gas temperature, solid particle temperature and outlet gas temperature during time were carefully measured. To analyze these data by using regression analysis to predict solid particle and outlet gas temperature, 2 correlations on initial pa-rameters were presented. The result has shown that temperature gradients in the beginning of fluidization, is very high and therefore the exponential functions in the regression model is used to predict the temperature changes.
基金Project supported by the National Natural Science Foundation of China(No. 50278036)the Natural Science Foundation of Guangdong Province (No. 04105951)
文摘A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.
文摘In order to research the changing process of the pollution from the formation of Nansihu Lake, this study determined the isotope age and depositional rate and analyzed the organic geo-chemical quotas and heavy metal quotas of two sedimentary profiles of Weishan and Dushan lakes. Research results showed that from the formation of Nansihu Lake, the change of the pollution could be divided into four phrases. At the early phrase of the formation, the organic matters of the lake mainly derived from the exotic matters and had a close relation to the effect on the water and sands from the Huanghe (Yellow) River. At the middle and late phrases of the development, the endogenous matters of the lake became the main and stable source of the organic matters. The overflow of the Huanghe River, the excavation of the Grand Canal and the cut of trees caused the changes of the historic pollution. In recent 20 years, the modern industrial pollution from the organic matters and heavy metals has an increasingly heavy tendency.
