GB695623A - Improvements in or relating to apparatus for removing temporary and permanent hardness from water by passing it througha bed of cation-exchange material - Google Patents

Abstract

695.623. Ion exchange treatment. FILTRATORS, Ltd., and STREATFIELD, E. L. April 11, 1950 [April 13, 19491. No. 9968/49. Class 46 [Also in Group XL(b)] In a cation exchange apparatus for softening water containing ammonia the treatment bed absorbs both hardness and ammonia while fresh but ammonia reappears in the effluent when the bed is aaproaching exhaustion, which is detected by continuously sampling the effluent, mixing it with Nessler reagent, intermittently delivering the mixture to a photoelectric device which differentially compares the colour with that of untreated water and produces an amplified signal operating a measuring instrument to indicate the effluent ammonia content arid/or a relay operating at a predetermined signal level to initiate regenerative treatment of the bed. Water is softened by passing it over a bed of cation exchange material such as a carbonaceous zeolite, and porous sampling pots positioned near the outflow of the bed, Fig. 1 (not shown), are connected through a pipe A4 and a needle valve A8 to a constant head reservoir A5, Fig. 2, having delivery pipes B<SP>1</SP> B<SP>2</SP>. Pipe B<SP>2</SP> conveys water through a needle valve L<SP>2</SP>, Fig. 5 (not shown), in a housing L to a light transmission cell K having optically plane glass endplates K<SP>1</SP> through which light passes from a lamp M and iris N<SP>1</SP> to a photocell. O<SP>1</SP>. Pipe B<SP>1</SP> conveys water through a needle valve. Fig. 4 (not shown), to a mixing chamber G containing a conical baffle H perforated at H', and a self starting syphon tube J which periodically discharges the contents to a second light transmission cell K through which light passes from the lamp M and iris N to a photocelil O. Nessler's reagent contained in a tank D is continuously dispensed through a constant-head reservoir containing a float operated valve, Fig. 3 (not shown), and a needle valve, Fig. 4 (not shown), to the mixing chamber and produces a coleration indicative of the ammonia content of the effluent and thus of the proximity of the bed to exhaustion. tion to the input of a twin triode neon stabilized amplifier (not shown), operating a milliammeter Q and a relay initiating an alarm or control system for automatically effecting the regeneration of the water treatment bed. A Chance no. O B1.O blue filter is desirably interposed between the light source and the transmission cells, and the apparatus is initially adjusted by the iris diaphragms N, N<SP>1</SP> for zero indication with the light transmission, cells respectively filled, with distilled water and distilled water containing the appropriate proportion of Nessler's reagent. Normally the indication is zero while the effluent is ammonia free, but the coloration due to ammonia present on approaching exhaustion of the bed unbalances the photocell outputs, deflects the milliammeter, and at a predetermined level operates the control relay to initiate regeneration. The automatic syphon is proportioned so that the interval between successive operations is sufficient for the completion of the test reaction. Specification 695,638, [Group XL(b)], is referred to.