Mathematical modelling of climbing film evaporators.
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Date
2001
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Abstract
Climbing film evaporators are in widespread use in the South African sugar industry, with
the vast majority of the local sugar mills currently utilising these evaporators as first effect
vessels in multiple effect evaporator sets. However, it is generally considered that the
performance of these evaporators has not been maximised, and that improvements could
be achieved by proper optimisation of the operating parameters. Unfortunately, very little
comprehensive design information has been published in the literature. owing to the
complexity of the heat transfer and hydrodynamic interactions in the evaporator tube.
Attempts at performance improvement have been hampered by the lack of any theory to
explain fully the effects of the operating parameters and physical properties of the feed
liquor on the performance of the evaporator.
In this study. a mathematical model of the climbing film evaporator system was developed
in order to assess the effects of changing operating conditions on evaporator performance,
based on as solid a theoretical foundation as cunendy possible. The model was tested
against experimental data from a pilot plant climbing film evaporator and this
experimental data was used to enhance the accuracy of the model by means of process
identification.
Because of the complexity of the model and the extensive computational time required for
its solution, a simplified evaporator model was also developed, based on Iinearisation of
the system of ordinary differential equations describing the climbing film evaporator
system. This simplified model was used to predict trends in evaporator behaviour under
various operating conditions.
Description
Thesis (M.Sc.Eng.)-University of Natal, Durban, 2001.
Keywords
Evaporators., Evaporators--Mathematical models., Sugar--Manufacture and refining., Theses--Chemical engineering.