METHOD FOR THE MEASUREMENT AND CONTROL OF DISSOLVED CHLORINE

1280272 Electro-chemical analysis CHLORINATION EQUIPMENT Ltd 30 Dec 1970 [23 April 1970] 19511/70 Heading G1N To determine the residual chlorine in effluent from a sterilizing plant the conductivity of the effluent is compared with that of the untreated water and the difference signal used to control the electrolytic generation of chlorine to provide equal residual in the untreated sample. The amplitude of the generater current to maintain equal conductivities, with a predetermined rate of fluid-flow, is a measure of the chlorine added in the sterilizing plant. As shown untreated water flows in line 1 and treated water in line 2. Both lines flow through a heat exchanger 5 to bring them to the same temperature and thence to respective cells 10, 11 and out at overflows 19. The electrodes are connected in a bridge circuit, Fig. 2 (not shown), to provide an output dependent on the difference in conductivities, and this signal is amplified to energize an electrolytic generator cell 24 providing chlorine on line 21 to mix with the untreated water. Hydrogen generated at electrode 23 is vented via line 26 and a liquid-level-balancing column 14. Modifications. The cells 10, 11 may be voltage generating instead of conductivity cells. The use of a reverse current possibly with a third electrode for electrolytic cleaning of electrodes is mentioned.