Showing papers on "Process variable published in 1972"

Constraint control system for optimizing performance of process units

Abstract: A control system which automatically optimizes the performance of a process unit by continuously scanning the important operating variables, measuring the deviation of these variables from a preselected target, identifying the instant limiting variable, calculating the change in a manipulated variable required to bring the most limiting variable to its target, adjusting the manipulated variable to make the calculated change, correcting operating conditions outside the control system to relieve the instant limit, and repeating the control process to identify a new limiting variable and to make changes needed to bring the new limiting variable to its target.

Optimising controller for process plants

Abstract: 1,262,711 Optimising control FOXBOROYOXALL Ltd April 9, 1970 [Jan 23, 1969], No3975/69 Heading G3R In a system for automatically maximising or minimising a process variable, a step change is made in the value of a controlling variable and, after a delay, the new magnitude of a controlled variable is stored and compared with its previous value so that the controlling variable is correctively adjusted in dependence on the difference, the step change being removed or retained as appropriate before the next control sequence In atransistorized control system, Fig 1, a multivibrator 6 periodically controls a logic circuit 5 so that an adjustable step signal is applied through a lead 14 to a control unit 9 to produce a step change in a variable MV controlling a process P After an interval sufficient for the change to become effective, logic circuit 5 operates switches in a measuring unit 2 so that the value of a dependent process variable CV, filtered and capacitively stored at 2, is compared with its previous value similarly stored The difference, stored at 3, is applied to control unit 9 to change the controlling variable by acorresponding amount in a corresponding sense A discriminator 4 determines whether the difference exceeds a predetermined adjustable value, in such sense as to approach the maximum or minimum value desired and, if so, prevents, through a line 17 or 18, removal of the step change until the improvement is insufficient or negative The step change is finally applied and removed alternately to maintain the system oscillating about the maximum or minimum Detailed circuits which include manually adjustable controls are described

A parameter adjustable regulator for a winding process

Abstract: A parameter imbedding method for simplified near-optimum design of a class of nonlinear systems is presented. It is applied to the design of a tension regulator system for a strip winding process. The feedback controller is continuously adjusted to follow a slowly varying process variable. Results of a simulation test for a particular steel-strip rolling mill are included.

Heating of a Thin Yarn on an Internally Heated Rotating Roll: Part I: Roll-Surface Temperature

Abstract: Heated, rotating rolls are commonly used for heat-treatment of fiber yarns. In such systems, the roll-surface tem perature is a critical process variable. In this paper, heat transfer from a rotating roll is analyzed, using the literature on heat transfer from rotating cylinders and disks. Equations are developed to relate the roll-surface temperature to other process variables. Comparison with some experimental measurements is also presented. These measurements show a significant nonuniformity of temperature on the roll surface.