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Model for continuous drying of solids in fluidized/spouted beds
Author(s) -
Viswanathan K.
Publication year - 1986
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450640113
Subject(s) - thermodynamics , moisture , humidity , bar (unit) , fluidized bed , water content , constant (computer programming) , fluidization , chemistry , mechanics , physics , meteorology , geotechnical engineering , geology , organic chemistry , computer science , programming language
A mathematical model is presented for predicting the dynamics of continuous drying of solids in fluidized and spouted beds (start‐up period). The outlet solids moisture content \documentclass[article]\pagestyle[empty]\begin[document]$ \bar Q $ \end[document] , the outlet humidity and the solids temperature are predicted as a function of time for both falling (internal diffusion controlled) and constant rate drying periods. It is shown that the initial moisture content of the solids in the bed, Q d , is a critical variable. Three characteristic types of dynamic behaviour are identified depending upon the value of Q d . For falling rate, a large Q d results in unacceptably high \documentclass[article]\pagestyle[empty]\begin[document]$ \bar Q $ \end[document] in the initial periods whereas a small Q d results in excessive temperature rise which may cause damage to solids. For constant rate, the responses of outlet humidity and solids temperature are independent of Q d . Analytical expressions are derived for the time required to reach steady state, the solids moisture content, and temperature at steady state. The model should also be useful for control of dryers.