Influence of Flow Development Time on the Residence Time Distribution and Flow Pattern in a Scale Model of a Water Treatment Plant Clearwell

2008 ◽  
Author(s):  
Xiaoli Yu ◽  
K. A. Mazurek ◽  
G. Putz ◽  
C. Albers
Keyword(s):  
Water Treatment ◽  
Flow Pattern ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Development Time ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Scale Model ◽  
Flow Development

Physical and computational modelling of residence and flow development time in a large municipal disinfection clearwell

2010 ◽  
Vol 37 (6) ◽  
pp. 931-940 ◽  
Author(s):  
Xiaoli Yu ◽  
Kerry Anne Mazurek ◽  
Gordon Putz ◽  
Cory Albers
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Development Time ◽  
Transient Flow ◽  
Treatment Plant ◽  
Operating Conditions ◽  
Scale Model ◽  
Tracer Studies ◽  
Flow Development

In this study, a two-dimensional, depth-averaged computational model (River2DMix) was used to predict the flow pattern and residence time distribution for flow through the Calgary Glenmore Water Treatment Plant northeast clearwell. Results are compared to those from flow visualization and tracer studies in a 1 : 19 scale model of the clearwell, as well as tracer studies conducted at the plant. Tests were carried out for three flow rates that ranged from minimum to maximum operating conditions. A key observation in the physical model was that it was necessary to let the flow fully develop before starting a tracer test to determine the residence time distribution. This flow development time to achieve steady-state results was approximately 10.5 h at the minimum flow rate tested. Results also show that it was unnecessary to model the structural columns either in the simulation or the scale model for developed flow in this clearwell, although for undeveloped or transient flow conditions the columns were important to consider.

Application of computational fluid dynamics (CFD) to ozone contactor optimization

2006 ◽  
Vol 6 (4) ◽  
pp. 9-16 ◽  
Author(s):  
J. Li ◽  
J. Zhang ◽  
J. Miao ◽  
J. Ma ◽  
W. Dong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Treatment ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Original Design ◽  
Computational Fluid Dynamics Cfd ◽  
Ozone Contactor

Many approaches have been used to model the performance and efficiency of ozone contactors based on some assumptions to characterize the backmixing in fluids. Recently, computational fluid dynamics (CFD) technique has been proposed to simulate and optimize ozone contactors by calculating residence time distribution of fluid. To improve the ozone contactor performance of Bijianshan Water Treatment Plant in Shenzhen in South China, CFD was used for simulation and development of new optimization measures. Results showed that the low depth/length ratio of the contactor chambers in the original design resulted in short circuiting and backmixing, with the T10/HRT being only 0.40. Installation of guide plates substantially reduced short circuiting and backmixing with a much higher T10/HRT (0.66), increased by 73% compared with the original design.

Residence time distribution analysis as related to the effective contact time

1999 ◽  
Vol 26 (2) ◽  
pp. 135-144 ◽  
Author(s):  
L E Liem ◽  
S J Stanley ◽  
Daniel W Smith
Keyword(s):  
Water Treatment ◽  
Residence Time ◽  
Time Distribution ◽  
Contact Time ◽  
Residence Time Distribution ◽  
Relative Concentration ◽  
Poor Performance ◽  
Distribution Analysis ◽  
Component Design ◽  
Effective Contact

Sixteen full-scale tracer studies were completed at two water treatment plants to assess disinfection performance under the concentration-time (CT) concept. The step residence time distribution (F RTD) was developed for each case. The value of the effective contact time, t10, in the CT concept was then obtained. For reservoirs without baffles, the t10 values were found to be much smaller than the expected values, indicating poor performance under the CT concept. Several models were used to interpret the F RTD characteristics, but the results were unsatisfactory. The standard jet model was then applied and was able to match the field data F RTD curve up to the relative concentration c/co [Formula: see text] 0.2. This showed that the momentum causing jet was responsible for the rapid movement of water through the system causing small t10 values. The work shows the importance of the momentum causing jet in reservoirs, and that in addition to traditional criteria it should be considered in the evaluation of water treatment component design. Other models that are commonly used to predict the t10 value should be applied carefully as a result of this jet effect.Key words: tracer study, F RTD, t10, CT concept, jet, water treatment component design.

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