Abstract
10.5 lakh tonnes of caustic soda is produced in India based on the membrane cell technology. Though membrane cells require 700 KWh lesser electrical energy per tonne of caustic, they produce caustic of concentration 32-33 wt%, which has to be concentrated to 45-46 wt% to meet the needs of the consumers. Concentration is now being done by thermal evaporators. Every tonne of 32-33 wt% caustic requires 0.75 tonne of steam for concentration. 8 lakh tonnes of steam is being consumed per annum for this purpose. In the present paper an electrochemical concentrator is proposed to replace the thermal evaporators.