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Heat and Mass Transfer

, Volume 54, Issue 3, pp 641–649 | Cite as

Effect of distributor on performance of a continuous fluidized bed dryer

  • D. Yogendrasasidhar
  • G. Srinivas
  • Y. Pydi Setty
Original
  • 133 Downloads

Abstract

Proper gas distribution is very important in fluidized bed drying in industrial practice. Improper distribution of gas may lead to non-idealities like channeling, short circuiting and accumulation which gives rise to non-uniform quality of dried product. Gas distribution depends on the distributor plate used. Gas distribution mainly depends on orifice diameter, number of orifices and opening area of the distributor plate. Small orifice diameter leads to clogging, and a large orifice diameter gives uneven distribution of gas. The present work involves experimental studies using different distributor plates and simulation studies using ASPEN PLUS steady state simulator. The effect of various parameters such as orifice diameter, number of orifices and the opening area of the distributor plate on the performance of fluidized bed dryer have been studied through simulation and experimentation. Simulations were carried out (i) with increasing air inlet temperature to study the characteristics of solid temperature and moisture in outlet (ii) with increasing orifice diameter and (iii) with increase in number orifices to study the solid outlet temperature profiles. It can be observed from the simulation that, an increase in orifice diameter and number orifices increases solid outlet temperature upto certain condition and then after there is no effect with further increase. Experiments were carried out with increasing opening area (3.4 to 42%) in the form of increasing orifice diameter keeping the number of orifices constant and increasing number of orifices of the distributor plate keeping the orifice diameter constant. It can be seen that the drying rate and solid outlet temperature increase upto certain condition and then after with further increase in the orifice diameter and number of orifices, the change in the drying rate and solid outlet temperature observed is little. The optimum values of orifice diameter and number of orifices from experimentation are found to be 5 mm and 60 (22% opening area).

List of symbols

Cp

Specific heat for (J/kg.K)

m

Mass flow rate of air (kg/s)

MR

Moisture ratio

Mi

Initial moisture content

Me

Equilibrium moisture content

Mt

Moisture content of solids with respect to time

r

Radius of particle (m)

t

Time (s)

Tgin

Gas inlet temperature (K)

Tgout

Gas outlet temperature (K)

Tsin

Solids inlet temperature (K)

Tsout

Solids outlet temperature (K)

V

Velocity of air (m/s)

Subscripts

e

Equilibrium

i

Initial

t

Time

gin

Gas in

gout

Gas out

sin

Solids in

sout

Solids out

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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  • D. Yogendrasasidhar
    • 1
  • G. Srinivas
    • 1
  • Y. Pydi Setty
    • 1
  1. 1.Department of Chemical EngineeringNational Institute of Technology WarangalWarangalIndia

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