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Characterization of hydrodynamics an...

Fotovat, Farzam.

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Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass./
作者:	Fotovat, Farzam.
面頁冊數:	195 p.
附註:	Source: Dissertation Abstracts International, Volume: 75-12(E), Section: B.
Contained By:	Dissertation Abstracts International75-12B(E).
標題:	Chemical engineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3582673
ISBN:	9781321209976

Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass.
Fotovat, Farzam.

Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass. - 195 p.

Source: Dissertation Abstracts International, Volume: 75-12(E), Section: B.

Thesis (Ph.D.)--Ecole Polytechnique, Montreal (Canada), 2014.

This item must not be sold to any third party vendors.

This thesis focuses on the characterization of hydrodynamics and mixing phenomena in fluidized beds containing mixtures of sand and irregular biomass particles. The first objective of this study is understanding the effect of the large biomass particles on the bubbling characteristics and gas distribution pattern of sand fluidized beds. The second objective is the characterization of mixing/segregation of biomass and sand particles under fluidization conditions.

ISBN: 9781321209976Subjects--Topical Terms:

560457
Chemical engineering.

Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass.
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100 1 $a Fotovat, Farzam. $3 3177105
245 1 0 $a Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass.
300 $a 195 p.
500 $a Source: Dissertation Abstracts International, Volume: 75-12(E), Section: B.
500 $a Advisers: Jamal Chaouki; Jeffrey M. Bergthorson.
502 $a Thesis (Ph.D.)--Ecole Polytechnique, Montreal (Canada), 2014.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a This thesis focuses on the characterization of hydrodynamics and mixing phenomena in fluidized beds containing mixtures of sand and irregular biomass particles. The first objective of this study is understanding the effect of the large biomass particles on the bubbling characteristics and gas distribution pattern of sand fluidized beds. The second objective is the characterization of mixing/segregation of biomass and sand particles under fluidization conditions.
520 $a A variety of experimental techniques are employed to study the behavior of two constituting phases of a fluidized bed, i.e., dilute (bubble) and dense (emulsion) phases. Exploring the characteristic fluidization velocities of sand-biomass mixtures unveils that the onset of bubbling in these systems occurs at a higher gas velocity compared to that of the initial fluidization velocity (Uif). The initial bubbling velocity (Uib), the final fluidization velocity ( Uff), and the transition gas velocity from bubbling to turbulent regime (Uc) rise by increasing the fraction of biomass in the mixture. Statistical analysis of the pressure signal at top of the bed reveals that increasing the biomass load hinders the evolution of bubbles at a low gas velocity (U<0.6 m/s), while at high velocities, the bubbling trend of beds containing different fractions of biomass is comparable. The addition of biomass particles to a bed of sand leads to an increase in the mean voidage of the bed; however, the voidage of each phase remains unaffected. It is observed that large biomass particles trigger a break-up of the bubbles, which results in boosting bubbling frequency. The fraction of bubbles at the center of the bed increases with the load of biomass. At the wall region, however, it starts to decrease by adding 2% wt. biomass to pure sand and then increases with the further addition of biomass.
520 $a The Radioactive Particle Tracking (RPT) technique is implemented in the second section of this work to study the motion and distribution of biomass particles at U=0.36 m/s and U=0.64 m/s. In this regard, an active biomass particle is tracked for a long period of time and its instantaneous position is recorded. The acquired data is then processed to achieve the time-averaged concentration profile of biomass particles. This profile represents the segregation of biomass particles, which tend to accumulate in the upper levels of the bed. Changes in the fraction of biomass with increasing gas velocity are inferred from the local changes of the time-averaged pressure drop values at the top of the bed. To determine the parameters affecting the movement and segregation of biomass particles, their circulatory motion is also scrutinized using the RPT data. The circulation of biomass is impeded when the load of biomass rises at U=0.36 m/s, resulting in a more pronounced segregation of sand and biomass. The opposite trend is observed at U=0.64 m/s. This prompts a more uniform distribution of particles along the bed and brings about a higher degree of mixing. The average rise velocity of biomass is 0.2 times the bubble velocity, regardless of the biomass load or fluidization velocity. A one-dimensional model is proposed to predict the volume fraction of biomass along the bed. Some of the terms of this model are linked to the fluidizing behavior of biomass particles as deduced from the RPT findings.
520 $a The fluidization of sand and cylindrical biomass particles is also simulated using the BARRACUDA CPFD software, which is based on the Lagrangian-Eulerian approach. Simulation and experimental results are compared in order to evaluate the capability of the numerical approach to predict the bubbling characteristics of the sand-biomass mixture for systems differing in composition and fluidization velocity.
520 $a The last part of this thesis is devoted to the separation of the main components of the shredded bulky waste. A step-wise process has been developed based on the elutriation and density segregation techniques. After removal of the light and interwoven species of the shredded waste by elutriation, the nonelutriated materials are further separated into two successive fluidization columns. Polypropylene and glass beads are introduced as the fluidization media in these columns in order to make density segregation of the target and not-target components possible. Hence, undesirable combustible matters and hard plastic are separated as the overflow of the first and second fluidization steps. A second elutriation column is also devised to separate and recover fiber and soft plastic. To determine optimal operating conditions, several influential parameters, such as the elutriation velocity and time, the size and density of the fluidization media, and the initial configuration of the feedstock and bed material, are explored. The kinetics of segregation is also derived for both fluidization steps. (Abstract shortened by UMI.).
590 $a School code: 1105.
650 4 $a Chemical engineering. $3 560457
650 4 $a Alternative Energy. $3 1035473
650 4 $a Energy. $3 876794
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710 2 $a Ecole Polytechnique, Montreal (Canada). $b Genie Chimique. $3 3169940
773 0 $t Dissertation Abstracts International $g 75-12B(E).
790 $a 1105
791 $a Ph.D.
792 $a 2014
793 $a English
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