MANUFACTURE OF ANHYDROUS CAUSTIC SODA FROM AQUEOUS CAUSTIC SODA SOLUTION

摘要

PURPOSE:To manufacture anhydrous NaOH with high thermal efficiency by concentrating an aqueous NaOH soln. to a predetermined concn. with a liq. film rising type concentrator and feeding the concd. soln. into a liq. film falling type concentrator from the top in the tangential direction together with the resulting steam to heat dehydrate the soln. CONSTITUTION:An aqueous NaOH soln. of =45% concn. is fed 4 into liq. film rising type concentrator 1 from the bottom and allowed to rise in concentrator 1. By supplying 2 high pressure steam of =8kg/cm2, a mixture of the soln. concd. to =55% concn. and steam is taken out of top 5. This mixture is fed into whirling chamber 7 of liq. film falling type concentrator 6 in the tangential direction, and a heat medium of 350-500 deg.C is introduced 8 from a lower portion of concentrator 6 and discharged 9 from an upper portion. A mixture of fused NaOH concd. to anhydrous NaOH in concentrator 6 and steam is then sent to vapor-liq. separator 11 through discharge pipe 10 to exhaust 12 the steam, and the fused NaOH is taken out of product taking-out pipe 13.