IN-LINE PH AND PION CONTROLLER

摘要

The location of a number of larger than two of pH or pIon sensors (3) for ionic composition control are distributed over the cross-sectional area of the process line. Each individual sensor signal is digitized and converted to its antilogarithm (28) and these antilogarithms are averaged to a control signal (29, 30) in the form of a binary word, for a binary reagent dispensing system (21, 11, 12, 13, 18, 19). Reagent (21) from this system is transported by a carrier liquid (23) and dispensed from orifices (4) distributed over the cross-section of the process line, downstream of the sensors (3). Upstream of the sensors (3), a backmixing passive mixer (2) homogenizes the process stream; downstream of the reagent orifices (4) a non-backmixing passive mixer (5) homogenizes process liquid plus reagent (21). This control section (28, 29) of the process line may be followed by a second, identical section (8, 9, 10) dispensing diluted reagent (25), while its averaged control signal (30) may also be fed back to the data processor (29) processing the control signal of the first section in order to optimize first section dispenser control. The data processors (29, 30) also multiply the composition signal with process stream flow rate as measured by a flowmeter (1), and shut off the system if flow rate drops below a minimum. A final section containing only distributed sensors (6) followed by a backmixing static mixer for final homogenization may replace or follow the second control section; averaged signal is used for the feedback optimization (28) of the control by the preceding section, and for final monitoring of the adjusted process.