In
the production of purified terephthalic acid (PTA), the acetic
acid solvent dehydration system is a typical heterogeneous azeotropic
distillation system. In this work, a rigorous process simulation of
the complete industrial acetic acid solvent dehydration process is
conducted. To achieve both the bottom- and top-product specifications,
remove the accumulated p-xylene (PX), and recycle
the methyl acetate (MA) despite feed flow rate disturbances, a suitable
control strategy of this complete system is proposed. The control
strategy requires only a side draw and organic reflux to control the
tray temperatures of the dehydration column, the bottom heating steam
to control the tray temperature of the PX purification column, and
top-product reflux to control the tray temperature of the entrainer
recovery column; this strategy can be easily implemented in industry
for wider applications. From dynamic simulation and analysis, the
control strategy can maintain the product purities, overcome the drawback
of the PX imbalance, achieve the transition to the desired operation
more quickly, and better maintain the stability of the overall solvent
dehydration system under a disturbance in the upper-zone feed streams.