GB1250158A - - Google Patents

Abstract

1,250,158. Concentration of liquors by evaporation. PARKSON INDUSTRIAL EQUIPMENT CO. Ltd. 11 Dec., 1968 [12 Dec., 1967], No. 56450/67. Heading B1B. [Also in Division G3] In a system in which liquid is continuously re-circulated at constant velocity through an evaporator and a separator which removes vapour, the pressure upstream of the evaporator automatically controls the rate of withdrawal of liquid from the system. As shown, a feed pump 1 supplies dilute liquor to an evaporator 2 from the output of which vapour is removed for supply to a condenser by a separator 3. More concentrated liquor is returned from separator 3 to evaporator 2 by a pump 5 and'the viscosity of this liquor is measured by a pressure detector 6 which produces a pneumatic signal for comparison at 7 with a signal representing desired viscosity. Any difference is effective to control a fluid-pressure servomotor 8 which then adjusts the speed of a pump 9 withdrawing concentrated liquor from the system until the desired concentration is restored. Pump 9 may not start until the concentration approaches the desired value. Pressure detector 6 may alternatively produce a voltage controlling the speed of pump 9, The level of concentrated liquor from separator 3 is maintained constant by a signal from a level detector 10 which controls a servomotor 1a adjusting the speed of feed pump.