A method for the preparation of anhydrous sodium sulfate from viskosekoagulierbaedern

摘要

PICT:1038175/C1/1 Anhydrous Na2SO4 is recovered from a viscose coagulation bath by cooling the coagulation bath in a crystallizer by expansion under vacuum, allowing the water vapour produced to pass into an absorber in which it undergoes exothermic reaction with CH2SO4, passing the hot acid into a heat exchanger to which is supplied sodium sulphate decahydrate originating in the vacuum crystallizer, and thus dehydrating the hydrous salt. Additional heat from a separate source may be supplied to the heat exchanger. A viscose coagulation bath enters vacuum evaporator or crystallizer 1 by conduit 2 and is withdrawn therefrom, cooled and containing Na2SO410H2O, by conduit 3 opening into the casing of heat exchanger 4. Water vapour from 1 is withdrawn by conduit 5 into absorber 6 where it condenses and is absorbed by sulphuric acid introduced by conduit 7. Sulphuric acid is continuously cycled in the circuit consisting of absorber 6, pump 8, serpentine 9 of exchanger 4 and conduit 7. Concentrated H2SO4, e.g. at 66 DEG Bae, is introduced into the circuit by conduit 10 connected to conduit 7 and dilute acid may be removed by conduit 11 as necessary. Sodium sulphate entering as the decahydrate into exchanger 4 is dehydrated therein and withdrawn by conduit 12. Steam is removed from 4 by conduit 13 and condensed elsewhere. Additional heat if required may be supplied to 4 by means of auxiliary serpentine 15.