The effect of operating conditions on the residence time distribution and axial dispersion coefficient of a cohesive powder in a rotary kiln

2017 ◽  
Vol 158 ◽  
pp. 50-57 ◽  
Author(s):  
Ingrid J. Paredes ◽  
Bereket Yohannes ◽  
Heather Emady ◽  
Benjamin J. Glasser ◽  
William G. Borghard ◽  
...  
Keyword(s):  
Residence Time ◽  
Rotary Kiln ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Dispersion Coefficient ◽  
Operating Conditions ◽  
Axial Dispersion ◽  
Axial Dispersion Coefficient ◽  
Cohesive Powder

scholarly journals Residence time distribution and flow pattern modeling of oilseeds in a pilot screw press

OCL ◽  
2020 ◽  
Vol 27 ◽  
pp. 65
Author(s):  
Laurine Bogaert ◽  
Houcine Mhemdi ◽  
Eugène Vorobiev
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Rotation Speed ◽  
Screw Press ◽  
Operating Conditions ◽  
Axial Dispersion ◽  
Experimental Methodology ◽  
Theoretical Approaches ◽  
The Press

Mechanical expression is widely applied for oil recovery from oilseeds using continuous screw presses. Despite significant recent advances in the field of press design and automation, it remains difficult to predict the press performances based on the theoretical approaches, and more experimental investigations are needed to clarify and characterize the seeds flow and expression behavior in the press. Residence Time Distribution (RTD) is a frequently used tool in chemical engineering to characterize the material flow by simple tracer tests. In this paper, we explore the feasibility of using RTD for the screw presses, in order to check the flow patterns homogeneity and identify the possible deviations depending on the press geometry and the operating conditions. Both theoretical modeling and experimental investigation are conducted for two different screw press designs (Reinartz and Olexa), and at the different rotation speeds. An original and reliable experimental methodology was developed by using erucic acid as tracer in the form of pulse injection and gas chromatography as detection method. Experimental results coupled with statistical calculations showed the influence of the screw geometry and the rotation speed on the seeds flow inside the press. The matter displacement was much faster and the experimental residence time was very close to the theoretical one indicating more homogeneity and less dispersion in the Olexa arrangement in comparison to the Reinartz arrangement. The higher variance observed at lower rotation speed (2.4 rpm) suggested the presence of flow defects like mixing and axial dispersion in the press. To complete the experimental work, axial dispersion model was applied, and allowed obtaining the valuable information, such as axial dispersion degree and distribution functions. Obtained results can be very useful to predict the performance of existing screw presses and design more efficient industrial equipments.

Measurement of the residence time distribution of a cohesive powder in a flighted rotary kiln

2018 ◽  
Vol 191 ◽  
pp. 56-66 ◽  
Author(s):  
Ingrid J. Paredes ◽  
Bereket Yohannes ◽  
Heather N. Emady ◽  
Fernando J. Muzzio ◽  
Al Maglio ◽  
...  
Keyword(s):  
Residence Time ◽  
Rotary Kiln ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Cohesive Powder

scholarly journals Optimization of a Continuous Hybrid Impeller Mixer via Computational Fluid Dynamics

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
N. Othman ◽  
S. K. Kamarudin ◽  
M. S. Takriff ◽  
M. I. Rosli ◽  
E. M. F. Engku Chik ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Operating Conditions ◽  
Impeller Speed ◽  
Transient Condition ◽  
Experimental Investigations ◽  
Rushton Turbine

This paper presents the preliminary steps required for conducting experiments to obtain the optimal operating conditions of a hybrid impeller mixer and to determine the residence time distribution (RTD) using computational fluid dynamics (CFD). In this paper, impeller speed and clearance parameters are examined. The hybrid impeller mixer consists of a single Rushton turbine mounted above a single pitched blade turbine (PBT). Four impeller speeds, 50, 100, 150, and 200 rpm, and four impeller clearances, 25, 50, 75, and 100 mm, were the operation variables used in this study. CFD was utilized to initially screen the parameter ranges to reduce the number of actual experiments needed. Afterward, the residence time distribution (RTD) was determined using the respective parameters. Finally, the Fluent-predicted RTD and the experimentally measured RTD were compared. The CFD investigations revealed that an impeller speed of 50 rpm and an impeller clearance of 25 mm were not viable for experimental investigations and were thus eliminated from further analyses. The determination of RTD using ak-εturbulence model was performed using CFD techniques. The multiple reference frame (MRF) was implemented and a steady state was initially achieved followed by a transient condition for RTD determination.

Sign in / Sign up

Export Citation Format

Share Document