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A 15% aqueous ethanol feed is
pumped by a magnetic-drive centrifugal pump through an electrical heater into a
small glass flash vaporizer.
Power to the heater is supplied either by a
variable transformer, or by an industrial PID controller. The controller may be
interfaced via the RS232C port of an IBM compatible microcomputer, and the
computer used to set the controller parameters and to acquire the temperature
data. Copper-constantan thermocouples measure the liquid and vapor
temperatures. Glass heat exchangers receive the effluent liquid and vapor
streams.
In the steady state mode, students
set the feed rate and heater power (or controller set point) and then collect,
weigh and analyze distillate and bottoms samples when a steady state has been
achieved. (The feed can be a mixture of several species, e.g., water, methanol,
ethanol, acetone, and propanol).
In the dynamics mode, the students
set the feed rate and heater power, allow the vaporizer to come to steady
state, and then impose a step change in heater power or feed rate. Transient
temperature data are recorded manually or acquired by the computer.
In the control mode, the power to the heater is under
feedback control, using an industrial PID controller. A computer can be used to
set the controller parameters and to acquire the transient data.
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