Sedimentation tanks and clarifiers play a significant role in an active sludge system, and the efficiency of the whole system is closely related with the design and operation of the sedimentation tanks. This paper foc...Sedimentation tanks and clarifiers play a significant role in an active sludge system, and the efficiency of the whole system is closely related with the design and operation of the sedimentation tanks. This paper focuses on the sludge concentration in each cross-section of the sedimentation tank. We measured the sludge concentration to explore its distribution inside the tank, carried in-situ tests to research the fluid pattern and real operational rules of the sedimentation tank. We also used the computational fluid dynamics (CFD) software, PHOENICS 3.5, to simulate the solid-liquid two-phase fluid inside the tank and describe the sludge concentration distribution. The numerical results indicate obviously a sludge-water interface and a compression interface inside the sedimentation tank, a stratified sedimentary region with uniform concentration and a compression region with high concentration at the bottom of the tank. Although the simulated concentrations deviated slightly from those of in-situ tests, they were still acceptable for identifying the sludge interfaces and fluid pattern inside a sedimentation tank, which are important parameters for optimizing the tank size and improving the settling efficiency.展开更多
A test system was designed to study the parameters affecting the volumetric efficiency of a thick-material pump for coal slime.The parameters studied included solid concentration,the slenderness ratio of the suction c...A test system was designed to study the parameters affecting the volumetric efficiency of a thick-material pump for coal slime.The parameters studied included solid concentration,the slenderness ratio of the suction cylinder and the running speed of the hydraulic cylinder.In the experiment the concentrations of coal slime were 75.7%,76.3%,74.4%,73.5%,72.1%and 70.63%;the running speeds were 0.23,0.18,0.13,0.10 and 0.08 m/s;and the slenderness ratios of the suction cylinder were 1.63,2.26,2.88,3.50,4.13,4.78 and 5.38.The results show that the suction volumetric efficiency decreases gradually with an increase in material concentration.The critical concentration value is 72%;below 72%the suction volumetric efficiency is above 90%,otherwise it decreases rapidly.When the solid concentration reaches 76.3%,the suction volumetric efficiency is only 40%.When the running speed of the piston is less than or equal to 0.23 m/s,the suction volumetric efficiency increases with an increase in running speed.展开更多
基金the Key Subject Supporting Project of Shanghai Government (No. 042312067)
文摘Sedimentation tanks and clarifiers play a significant role in an active sludge system, and the efficiency of the whole system is closely related with the design and operation of the sedimentation tanks. This paper focuses on the sludge concentration in each cross-section of the sedimentation tank. We measured the sludge concentration to explore its distribution inside the tank, carried in-situ tests to research the fluid pattern and real operational rules of the sedimentation tank. We also used the computational fluid dynamics (CFD) software, PHOENICS 3.5, to simulate the solid-liquid two-phase fluid inside the tank and describe the sludge concentration distribution. The numerical results indicate obviously a sludge-water interface and a compression interface inside the sedimentation tank, a stratified sedimentary region with uniform concentration and a compression region with high concentration at the bottom of the tank. Although the simulated concentrations deviated slightly from those of in-situ tests, they were still acceptable for identifying the sludge interfaces and fluid pattern inside a sedimentation tank, which are important parameters for optimizing the tank size and improving the settling efficiency.
基金Projects 02C26211100499 supported by Science and Technology Corporation Innovation Fund of China 20020290011 by the Ph.D Program Fund
文摘A test system was designed to study the parameters affecting the volumetric efficiency of a thick-material pump for coal slime.The parameters studied included solid concentration,the slenderness ratio of the suction cylinder and the running speed of the hydraulic cylinder.In the experiment the concentrations of coal slime were 75.7%,76.3%,74.4%,73.5%,72.1%and 70.63%;the running speeds were 0.23,0.18,0.13,0.10 and 0.08 m/s;and the slenderness ratios of the suction cylinder were 1.63,2.26,2.88,3.50,4.13,4.78 and 5.38.The results show that the suction volumetric efficiency decreases gradually with an increase in material concentration.The critical concentration value is 72%;below 72%the suction volumetric efficiency is above 90%,otherwise it decreases rapidly.When the solid concentration reaches 76.3%,the suction volumetric efficiency is only 40%.When the running speed of the piston is less than or equal to 0.23 m/s,the suction volumetric efficiency increases with an increase in running speed.
