PURPOSE: To maintain the concn. of a slurry in a crystallizer almost constant and carry out stable operation by detecting the concn. of NaOH in a soln. supplied to the crystallizer and controlling the supply of a refrigerant under specific conditions in direct contact of the soln. and refrigerant.
CONSTITUTION: A soln. of NaOH is supplied from pipe 1 to crystallizer 2, and a slurry of NaOH hydrate formed is taken out from pipe 8. On the other hand, a liquefied refrigerant is supplied from pipe 5 to crystallizer 2 through tank 3 and flow controller 4. The gasified refrigerant is passed through compressor 6, liquefied by condenser 7, and recycled. At this time, the concn. of NaOH in the soln. supplied is detected and converted into a temp. of the soln. in crystallizer 2 corresponding to the desired value of the slurry concn. in the crystallizer, and the supply of the refrigerant is controlled so that the temp. is attained
KOIKE MASAYUKI
OKAMOTO NORIAKI
MIYASHITA MASAICHI
MATSUI ETSUROU
ISHIKAWAJIMA HARIMA HEAVY IND