| 摘要 |
PURPOSE:To enhance the quality of purified salt fed to a salt water purifying process by allowing an electrolyte to complicatedly flow to a group of evaporators in a concentrating process when caustic soda is manufactured by a diaphragm electrolytic method. CONSTITUTION:In a concentrating process an electrolyte is first fed to the 2nd evaporator V2, passed through the 4th, 3d and 1st evaporators V4, V3, V1 in order, and sent to a cooling and filtering process through flash tank F1. On the other hand, heating steam is introduced into heater E1 of evaporator V1, and steam generated from each evaporator is used as a heat source for the next evaporator (in the order of V2-V4). High purity NaCl deposited in evaporators V2, V4 is taken out of leg L4 of V4 as pure salt, and Na2SO4-contg. NaCl deposited in evaporators V1, V3 is taken out of leg L3 of V3 as impure salt, which is then freed of the Na2SO4 to obtain purified salt fed to a salt water purifying process. |
