Automatic control for polymerisation reaction by viscosity - using computer based system for steam heating and stirring

Plant for the condensation polymerisation of melted polyethylene terephthalate polyester has at least two reactors in series, each with regulators for steam pressure, a control device for automatically regulating the molar viscosity number of the polymer emerging, and (a) a computer plus device to accept analogue input signals, a device to produce analogue output signals, a real time planner in the computer, and a device to supply and store a program (b) devices to produce analogue input examples for each reactor and to represent steam pressure, inlet and outlet viscosity, inlet and outlet temperatures, (c) storage for these analogue input examples in the computer, (d) a central finisher/processor in the computer to process the input examples by reference to the program, (e) a regulator for ths viscosity number of the polyester within certain limits of the program with a device before and after each reactor to scan the viscosity and temperature of the polyester before and after reaction; a signalling device to fix/regulate each steam pressure regulator as an approximation to a desired value which is determined by (1) the current viscosity (as set by the computer; the viscosity and temperature) of fed polymer compared with the previous value and (2) the previous calculated desired value of steam pressure; constants for the proportional yield, integral and differential time, and desired viscosity number of the final polymer minus that in at least two previous measurements and with intervals between measurements and a current desired value for steam pressure, solving these relationships by the computer which then provides signals to cause reaction by the steam pressure controls, and (f) an alarm/synchronisation/interceptor to alarm the operator and (optionally) to signal the computer if its controlled reactor conditions pass beyond limits which are set by the program; also whenever an input signal is not received at the planned time in the central processing device. Close control of reaction to a final viscosity within 0.5% variation.