UNIT AND METHOD FOR FLOW RATE CONTROL

摘要

PROBLEM TO BE SOLVED: To provide a unit for flow rate control which effectively sends a fluid from pipes having pumps respectively through a common main pipe under pressure, and a method therefor. SOLUTION: A mean flow rateαis calculated by dividing the total amountΣof fluids discharged from pipes 22-1 to 22-2 having pumps 14-1 to 14-1 respectively by the total number (n) of the pumps 14-1 to 14-4 in operation and when the absolute value of the subtraction outputγbetween the mean flow rateαand a set valueβexceeds a reference value (x) outputted from a control panel 19, a process held by an S/H (sample and hold circuit) for setting over the mean flow rateαagain as the set valueβis repeated and a smoothing circuit smoothes the set valueβwhich varies in steps corresponding to the mean flow rateα. PID (proportion.integration.differentiation) control circuits 20-1 and 20-2 control the opening degrees of valves 16-1 to 16-4 based on a pressure control signalβ' after smoothing.