A method for measuring the residence time distribution of particles in a fluidized bed based on digital image analysis

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jiamin Li ◽  
Xiaoping Chen ◽  
Jiliang Ma ◽  
Cai Liang
Keyword(s):  
Image Analysis ◽  
Fluidized Bed ◽  
Residence Time ◽  
Digital Image ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Digital Image Analysis ◽  
Color Space ◽  
The Difference ◽  
Accuracy And Repeatability

AbstractTraditional methods for measuring the residence time distribution (RTD) of particles in a fluidized bed are complex and time-consuming. To this regard, the present work proposes a new measurement method with remarkable efficiency based on digital image analysis. The dyed tracers are recognized in the images of the samples due to the difference of colors from bed materials. The HSV and the well-known RGB color space were employed to distinguish the tracers. By enhancing the Saturation and the Value in HSV and adjusting the gray range of images, the recognition error is effectively reduced. Then the pixels representing the tracers are distinguished, based on which the concentration of the tracers and RTD are measured. The efficiency, accuracy and repeatability of the method were validated by RTD measurements experiments. The method is also fit for distinguishing the target particles from multi-component systems consisting of particles of different colors.

Evaluation of membrane bioreactor performance via residence time distribution: effects of membrane configuration and mixing

2008 ◽  
Vol 57 (3) ◽  
pp. 353-359 ◽  
Author(s):  
Y. Wang ◽  
K. W. Ong ◽  
M. W. D. Brannock ◽  
G. L. Leslie
Keyword(s):  
Residence Time ◽  
Pilot Plant ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Hollow Fibre ◽  
Careful Consideration ◽  
Flat Sheet ◽  
Membrane Geometry ◽  
The Difference ◽  
The Republic

Unlike conventional wastewater treatment systems that have a single effluent discharge point, membrane bioreactors (MBR) may have multiple extraction points resulting from the location of the membrane element in the reactor. This leads to multiple residence time distributions for an MBR system. One method to characterise the mixing is based on the concept of residence time distribution (RTD). A set of RTDs were generated using the conservative tracer, lithium chloride, for pilot plant MBRs with capacity up to 300 m3/day. Flat sheet and hollow fibre pilot plant MBR systems were operated in parallel on primary effluent collected at the Bedok Water Reclamation Plant in the republic of Singapore. Analysis of the RTD profiles indicated that membrane geometry did not impact on the kinetic conversion associated with nitrification because both MBRs were in well mixed conditions. However, the energy required to achieve perfect mixing with a hollow fibre module MBR, as defined by the velocity gradient, was lower than that with a flat sheet module MBR. The implication is that energy input associated with reactor mixing will depend on the configuration of the membrane. The difference in energy requirements between flat sheets and hollow fibres is such that careful consideration should be given to membrane selection in larger municipal installations.

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