The development and validation of a system model for a countercurrent cascading rotary dryer

Journal Article · Sat Jan 01 04:00:00 EST 2000 · Drying Technology

DOI:https://doi.org/10.1080/07373930008917695· OSTI ID:20082155

Cao, W F; Langrish, T A.G.

An overall system model for a countercurrent rotary dryer has been developed with the ultimate aim of assessing controller pairings in these dryers. This model is based on heat and mass balances within dryer regions combined with two subsidiary models, one describing the equipment (which determines particle transport and heat transfer) and the other describing the behavior of the material (the drying kinetics). Six partial differential equations have been set up to evaluate six state variables: solids moisture content, solids temperature, gas humidity, gas temperature, solids holdup and gas holdup as functions of time and rotary dryer length. A control-volume method has been used to reduce the six partial differential equations with respect to time and the length of the rotary dryer to six ordinary differential equations in time. The drying model has been implemented in the SPEEDUP flowsheeting package (with FORTRAN subroutines). The model has been validated by fifteen experiments in a pilot scale countercurrent-flow rotary dryer (0.2m in diameter and 2m in length) using sorghum grain. The average discrepancy for the outlet solids moisture content between the simulation and the experiment is 6.4%. Also, the drying model predicts the outlet solids temperature with an average discrepancy of {minus}5.2%.

• Research Organization: Univ. of Sydney, New South Wales (AU)
• OSTI ID: 20082155
• Journal Information: Drying Technology, Journal Name: Drying Technology Journal Issue: 1-2 Vol. 18; ISSN DRTEDQ; ISSN 0737-3937
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
COUNTERFLOW SYSTEMS
DESIGN
DRYERS
HEAT TRANSFER
MASS TRANSFER
MATHEMATICAL MODELS
MOISTURE
PARAMETRIC ANALYSIS
PARTICULATES
VALIDATION