RECOVERING METHOD FOR HEAT ENERGY IN PRODUCTION STAGE FOR CAUSTIC SODA BY DIAPHRAGM ELECTROLYSIS

摘要

PURPOSE:To improve heat recovery rate with low equipment costs by using the steam of reduced pressure obtained from wet gaseous chlorine and/or wet gaseous hydrogen generated by electrolysis as heat sources for heating of refined salt water after compressing and heating said steam. CONSTITUTION:In a process for production of caustic soda by diaphragm electrolysis, the wet gaseous chlorine generated in an electrolytic cell 2 heats the refined salt water from a salt water refining device 1 in a heat exchanger 4. The wet gaseous hydrogen generated at the same instant generates steam of reduced pressure in an evaporator 11. The resultant steam of reduced pressure is sucked into a turbo blower 13, where the steam is pressurized and heated. The pressurized and heated steam heats the refined salt water in a heat exchanger 10 and is fed into the cell 2; at the same time, the steam itself condenses and returns to the evaporator 11. The above-mentioned heat exchanger 10 has a higher over-all coefft. of heat transfer for the purpose of using the steam contg. no uncondensed gases and contributes to a considerable reduction in equipment costs.