GB561908A - Electrical control of chemical apparatus - Google Patents

Abstract

561,908. Automatic control systems for chemical processes. AMERICAN CYANAMID CO. Oct. 2, 1942, No. 13870. Convention date, Nov. 26, 1941. [Class 38 (iv)] [Also in Group III] The ion removal capacity of a material is automatically maintained within definite limits by automatic control apparatus responsive to the pH of a fluid after passing over the material. The apparatus comprises reservoirs 70, 71 of alkali 80, 81 of acid and 90, 91 of water, piped as shown in Fig. 2 to containers 11, 21 for the material and comprising spring closed valves adapted to be opened electrically. The effluent from the containers 11, 21 may pass to glass- and reference-electrode cells 10, 20 for measuring its pH after passing downwardly through the material, or after passing upwardly when normally opened valves 156, 256 are electrically closed. The containers 11, 21 are preferably glass cylinders containing, or sintered, to a glass filter bed and hold a measured sample of resin. The apparatus comprises a normal pH recorder which is connected to the electrode cells in turn. It comprises a type-wheel for printing identity symbols on the record so that the progress of the ion removal value of each sample may be followed. An electric motor 100 drives cams 101, 111, 121 controlling the electromagnets of the valves to produce a given timed sequence of treatment of the samples and an electric motor 300 drives selector switches 301, 302, 303, the aforesaid type-wheel and cams closing switches 52, 62 in turn, each a short time after the selector switches have rendered the system responsive to a selected electrode cell. Cams 50, 60 operated by the recorder and responsive to the pH value measured close a switch 51, 61, one at a maximum value and the other at a minimum value so that the appropriate valves are actuated to change the electrolyte when the effluent reaches either pH value. The sequence provided by the arrangement described is : upward flow of water for 1 minute ; downward flow of water 20 minutes ; sodium hydroxide (I per cent) 30 minutes or until pH = 10.2; acid (.003N- two parts by weight H 2 SO 4' one part HCl) until pH = 4.2, followed by water for 20 minutes. Both samples are simultaneously regenerated by alkali or the apparatus may be modified to effect regeneration individually. More than two samples may be handled by an extended apparatus, indicating lamps show the treatment in progress in each container.