Improvements in or relating to the control of processes of which the rate of variation of the essential factor with respect to time varies with time

摘要

554,145. Controlling filtering processes. NORTHERN ALUMINIUM CO., Ltd., and HORSBURGH, W. W. Feb. 7, 1942, No. 1640. [Class 46] [Also in Groups XXIX, III and XXVIII] A device for use in controlling a process in which the rate of variation of an essential factor varies with time, comprises two elements moved at right angles to one another one at constant velocity and the other at a velocity varying with the rate of variation of the essential factor, a member moved by the elements, and means actuated by a change in the direction of movement of said member for exerting control or giving a signal. Examples of processes to which the invention is applicable are those comprising mass action, filtration or distillation, and those in which one function is asymptotic to another. The apparatus shown with the parts in their initial positions comprises blocks 2, 4 and a member 1 which is pivotally connected to the blocks and is also slidable with respect to the block 4. During filtration, the block 4 is moved to the left by a cord 7, drum 8a, and clockwork, and the member 2 is raised by a rod 6 connected to a float in the filtrate receiving chamber, thus causing a weighted block 12 to be raised, pawls 15 on the block slipping over ratchet teeth on a bar 17 pivoted to a counterbalanced lever 19. When the delivery rate of the filtrate falls off, the direction of movement of the member 1 is reversed, the bar 17 is moved down, a trigger 21 is moved, and the weighted bell crank lever 24 swings the bar 17 to operate a valve 29, or other means, e.g. an electric relay, to cause a signal to be given or filtration to be stopped.