168
Exercise AA - Proportional temperature input with PID
control
Objective
To control the temperature of water exiting a coil passing through a heated water
bath in a process vessel, with PID control of a gear pump driving flow into the coil
and time proportional control of the bath temperature.
Overview
The temperatures within the process vessel and coil are monitored using
thermocouple type sensors. Process fluid is passed through the coil within the vessel
using a gear pump, which is controlled by a PID controller that monitors the
temperature of the process fluid leaving the coil. The water within the vessel is
heated by a heating element, and heat is transferred to the water within the coil. The
water is heated by a heating element which is controlled by a time proportional
controller that monitors the temperature of the water bath within the process vessel.
Equipment Required
PCT40 bench with small process vessel containing a heating coil.
Equipment set up
Ensure that the apparatus has been set up according to the Installation section. The
lid with heating coil should be in position on the small process vessel, with the coil
surrounding the heating element. The apparatus should be connected to a suitable
PC with the PCT40 software installed, using the grey USB cable supplied.
Fill the small process vessel with water:
Using a length of tubing with a quick release fitting at both ends, connect the solenoid
valve SOL 1 to one of the fittings on the side of the small process vessel. Ensure that
the other fitting on the side of the process vessel is not connected.
Close the drain valve on the process vessel.
Run the PCT40 software and select ‘Section 8: Temperature Control (indirect
heating)’.
In the software, switch on the valve SOL 1 using the switch on the software screen
and watch as the small process vessel fills with water.
Wait until the coil inside the vessel is fully covered with water, then switch off SOL 1.
Disconnect the tube from the small process vessel and SOL 1.
Take the long length of tube with a quick-release fitting at one end and a drain valve
at the other. Connect this end to the other side of the coil, and direct the opposite end
of the tube to drain. Fully open the drain valve.
Take a length of tubing with a quick release fitting at both ends. Connect SOL 1 to
the right hand connection on the gear pump.
Take a length of tubing with a quick release fitting on one end and a Guest push
fitting on the other. Connect the other gear pump connection to the coil.
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