[ Objective] The research aimed to study pre-treatment effect of the domestic sewage by water-dropping aeration zeolite bed technology. [ Method] By water-dropping aeration manner, we conducted sewage reoxygenation. Z...[ Objective] The research aimed to study pre-treatment effect of the domestic sewage by water-dropping aeration zeolite bed technology. [ Method] By water-dropping aeration manner, we conducted sewage reoxygenation. Zeolite was used to replace traditional contact oxidization fill- er. We inspected oxygenation effect of the water-dropping aeration manner and removal efficiency of the pollutant in sewage after biological contact oxidation. [ Result] Under the experimental condition with water-dropping heights of 0.30, 0.45 and 0.60 m, average added values of the dissolved oxygen for raw water were respectively 2.4, 3.6 and 4.2 rag/l_ after water-dropping aeration. Under the situation with average HRT of 2 h, when COD, TN and TP of the influent were respectively 309.0 -464.0, 33.3 -95.0 and 4.0 -7.5 mg/L, their corresponding average removal rates were 47.25%, 46.39% and 40.75%. [ Conclusion] The research conducted useful attempt for high-efficiency and low-cost treatment of the domestic sewaqe in rural area.展开更多
A cold-model vertical multi-tube circulating fluidized bed evaporator was designed and built to conduct a visualization study on the pressure drop of a liquid–solid two-phase flow and the corresponding particle distr...A cold-model vertical multi-tube circulating fluidized bed evaporator was designed and built to conduct a visualization study on the pressure drop of a liquid–solid two-phase flow and the corresponding particle distribution.Water and polyformaldehyde particle(POM)were used as the liquid and solid phases,respectively.The effects of operating parameters such as the amount of added particles,circulating flow rate,and particle size were systematically investigated.The results showed that the addition of the particles increased the pressure drop in the vertical tube bundle.The maximum pressure drop ratios were 18.65%,21.15%,18.00%,and 21.15%within the experimental range of the amount of added particles for POM1,POM2,POM3,and POM4,respectively.The pressure drop ratio basically decreased with the increase in the circulating flow rate but fluctuated with the increase in the amount of added particles and particle size.The difference in pressure drop ratio decreased with the increase in the circulating flow rate.As the amount of added particles increased,the difference in pressure drop ratio fluctuated at low circulating flow rate but basically decreased at high circulating flow rate.The pressure drop in the vertical tube bundle accounted for about 70%of the overall pressure drop in the up-flow heating chamber and was the main component of the overall pressure within the experimental range.Three-dimensional phase diagrams were established to display the variation ranges of the pressure drop and pressure drop ratio in the vertical tube bundle corresponding to the operating parameters.The research results can provide some reference for the application of the fluidized bed heat transfer technology in the industry.展开更多
The rotating jet bed(RJB) has been developed by Zhejiang University of Technology,as a noveler type of gas-liquid mass-transfer unit than rotating zigzag bed(RZB).The rotor of RJB is composed of perforated concentric ...The rotating jet bed(RJB) has been developed by Zhejiang University of Technology,as a noveler type of gas-liquid mass-transfer unit than rotating zigzag bed(RZB).The rotor of RJB is composed of perforated concentric baffles fixed to a rotating disc.The top of the baffles is in the grooves of the stationary disc,preventing short cut of the gas.Experiments of total reflux distillation with RZB and two types of RJB were carried out with ethanol-water systems at atmospheric pressure.The two types of RJB are with rotor of mesh baffles and of shutter baffles,respectively.The results showed that the number of theoretical plates per meter of RJB,lower than that of RZB,increased with increasing rotational speed,and increased firstly and then decreased with increasing gas superficial F-factor.The maximum number of theoretical plates per meter is 40.7 for RJB with rotor of mesh baffles and 40.0 for RJB with rotor of shutter baffles.The specific pressure drop of RJB was far less than that of RZB.The gas phase film volumetric mass-transfer coefficients of RJB with rotor of mess baffles and shutter baffles were correlated with the Reynolds number,Grashof number and Schmidt number.The calculated value agreed well with the experimental value,and the average deviation was less than 15%.展开更多
Various river projects are underway in small rivers in Korea that typically have natural flows. However, recent findings have shown that damages could be aggravated by structures such as weirs and drop structures duri...Various river projects are underway in small rivers in Korea that typically have natural flows. However, recent findings have shown that damages could be aggravated by structures such as weirs and drop structures during flood incidents. Experimental studies for securing the stability of flood control for these artificial structures have been insufficient, and designs applying the existing domestic design standards would not be suitable for the steep flow sections such as the actual small rivers, possibly aggravating the damages. The present study involved hydraulic model experiments conducted in a laboratory to investigate the surrounding flow patterns according to the river bed slope at the downstream part of the weir model. Further, the scour characteristics in the apron section during the overflow of the structure were analyzed to determine the appropriateness of the apron length. Thus, as the upstream river bed slope gradually increased, the experimental scour length deviated more from the design criteria formula. The results suggest that both the formula suggested by the National Construction Research Institute and Bligh’s formula presented in the River Design Criteria are not suitable for steep-slope rivers, such as small rivers in Korea, because both formulas were proposed based on the seepage line distance and river bed materials without considering the slope of the river bed. Thus, in designing the apron and bed pitching of weirs and drop structures, the river bed slope, scour characteristics of weir overflow, and existing design factors should be comprehensively considered to devise a design formula appropriate for environment of the small rivers in Korea.展开更多
Flood damage has aggravated recently owing to artificial structures in high flow rare areas such as small rivers, which can lead to secondary damage. In this regard, studies are required to examine the conventional de...Flood damage has aggravated recently owing to artificial structures in high flow rare areas such as small rivers, which can lead to secondary damage. In this regard, studies are required to examine the conventional design criteria formulas to secure the stability of structures such as weirs and drop structures. Although studies on the stability of these structures have been conducted through small-scale experiments, few empirical studies have investigated the hydraulic phenomena occurring near actual artificial structures. In this study, we fabricated real-size models of weir and drop structure at the Andong River Experiment Center and investigated the flow patterns around the structures by applying the particle image velocimetry analysis technique with a flow tracker. We also measured the scour length in the waterspout section when the structures are overflowing, and compared it with the values calculated using the formula. Consequently, as the supply flow increases, the result is different from the value calculated using the formula given in the existing design standard, and it is judged to be inappropriate for a small stream area with high flow rate. Thus, it is necessary to consider the design factors such as energy gradient and the flow amount per unit width into weir and drop structure as well as the existing design factors in designing an apron section for a weir and drop structure.展开更多
基金Supported by Science and Technology Key Special Item of the National Water Body Pollution Control and Treatment, China(2010BAC68B02)
文摘[ Objective] The research aimed to study pre-treatment effect of the domestic sewage by water-dropping aeration zeolite bed technology. [ Method] By water-dropping aeration manner, we conducted sewage reoxygenation. Zeolite was used to replace traditional contact oxidization fill- er. We inspected oxygenation effect of the water-dropping aeration manner and removal efficiency of the pollutant in sewage after biological contact oxidation. [ Result] Under the experimental condition with water-dropping heights of 0.30, 0.45 and 0.60 m, average added values of the dissolved oxygen for raw water were respectively 2.4, 3.6 and 4.2 rag/l_ after water-dropping aeration. Under the situation with average HRT of 2 h, when COD, TN and TP of the influent were respectively 309.0 -464.0, 33.3 -95.0 and 4.0 -7.5 mg/L, their corresponding average removal rates were 47.25%, 46.39% and 40.75%. [ Conclusion] The research conducted useful attempt for high-efficiency and low-cost treatment of the domestic sewaqe in rural area.
基金supported by the open foundation of State Key Laboratory of Chemical Engineering (SKL-ChE-18B03)the Municipal Science and Technology Commission of Tianjin (No. 2009ZCKFGX01900)
文摘A cold-model vertical multi-tube circulating fluidized bed evaporator was designed and built to conduct a visualization study on the pressure drop of a liquid–solid two-phase flow and the corresponding particle distribution.Water and polyformaldehyde particle(POM)were used as the liquid and solid phases,respectively.The effects of operating parameters such as the amount of added particles,circulating flow rate,and particle size were systematically investigated.The results showed that the addition of the particles increased the pressure drop in the vertical tube bundle.The maximum pressure drop ratios were 18.65%,21.15%,18.00%,and 21.15%within the experimental range of the amount of added particles for POM1,POM2,POM3,and POM4,respectively.The pressure drop ratio basically decreased with the increase in the circulating flow rate but fluctuated with the increase in the amount of added particles and particle size.The difference in pressure drop ratio decreased with the increase in the circulating flow rate.As the amount of added particles increased,the difference in pressure drop ratio fluctuated at low circulating flow rate but basically decreased at high circulating flow rate.The pressure drop in the vertical tube bundle accounted for about 70%of the overall pressure drop in the up-flow heating chamber and was the main component of the overall pressure within the experimental range.Three-dimensional phase diagrams were established to display the variation ranges of the pressure drop and pressure drop ratio in the vertical tube bundle corresponding to the operating parameters.The research results can provide some reference for the application of the fluidized bed heat transfer technology in the industry.
文摘The rotating jet bed(RJB) has been developed by Zhejiang University of Technology,as a noveler type of gas-liquid mass-transfer unit than rotating zigzag bed(RZB).The rotor of RJB is composed of perforated concentric baffles fixed to a rotating disc.The top of the baffles is in the grooves of the stationary disc,preventing short cut of the gas.Experiments of total reflux distillation with RZB and two types of RJB were carried out with ethanol-water systems at atmospheric pressure.The two types of RJB are with rotor of mesh baffles and of shutter baffles,respectively.The results showed that the number of theoretical plates per meter of RJB,lower than that of RZB,increased with increasing rotational speed,and increased firstly and then decreased with increasing gas superficial F-factor.The maximum number of theoretical plates per meter is 40.7 for RJB with rotor of mesh baffles and 40.0 for RJB with rotor of shutter baffles.The specific pressure drop of RJB was far less than that of RZB.The gas phase film volumetric mass-transfer coefficients of RJB with rotor of mess baffles and shutter baffles were correlated with the Reynolds number,Grashof number and Schmidt number.The calculated value agreed well with the experimental value,and the average deviation was less than 15%.
文摘Various river projects are underway in small rivers in Korea that typically have natural flows. However, recent findings have shown that damages could be aggravated by structures such as weirs and drop structures during flood incidents. Experimental studies for securing the stability of flood control for these artificial structures have been insufficient, and designs applying the existing domestic design standards would not be suitable for the steep flow sections such as the actual small rivers, possibly aggravating the damages. The present study involved hydraulic model experiments conducted in a laboratory to investigate the surrounding flow patterns according to the river bed slope at the downstream part of the weir model. Further, the scour characteristics in the apron section during the overflow of the structure were analyzed to determine the appropriateness of the apron length. Thus, as the upstream river bed slope gradually increased, the experimental scour length deviated more from the design criteria formula. The results suggest that both the formula suggested by the National Construction Research Institute and Bligh’s formula presented in the River Design Criteria are not suitable for steep-slope rivers, such as small rivers in Korea, because both formulas were proposed based on the seepage line distance and river bed materials without considering the slope of the river bed. Thus, in designing the apron and bed pitching of weirs and drop structures, the river bed slope, scour characteristics of weir overflow, and existing design factors should be comprehensively considered to devise a design formula appropriate for environment of the small rivers in Korea.
文摘Flood damage has aggravated recently owing to artificial structures in high flow rare areas such as small rivers, which can lead to secondary damage. In this regard, studies are required to examine the conventional design criteria formulas to secure the stability of structures such as weirs and drop structures. Although studies on the stability of these structures have been conducted through small-scale experiments, few empirical studies have investigated the hydraulic phenomena occurring near actual artificial structures. In this study, we fabricated real-size models of weir and drop structure at the Andong River Experiment Center and investigated the flow patterns around the structures by applying the particle image velocimetry analysis technique with a flow tracker. We also measured the scour length in the waterspout section when the structures are overflowing, and compared it with the values calculated using the formula. Consequently, as the supply flow increases, the result is different from the value calculated using the formula given in the existing design standard, and it is judged to be inappropriate for a small stream area with high flow rate. Thus, it is necessary to consider the design factors such as energy gradient and the flow amount per unit width into weir and drop structure as well as the existing design factors in designing an apron section for a weir and drop structure.
