Patent ID: 6508915
Filing Date: 2003-01-21
Classification: B01D,C01B,Y10S

Abstract:
A method for distilling a solution containing nitric acid, comprising the steps of:feeding a first portion of the solution to a distiller; detecting a liquid level of the solution in the distiller with a liquid level detector disposed in the distiller; detecting a physical state of the solution in the distiller with a state detector, the state detector including a temperature sensor, a concentration sensor and a specific gravity sensor; controlling the amount of solution in the distiller based on the liquid level and physical state detection results; heating the solution in the distiller thereby forming a distillation vapor and a gas containing nitric acid and mist; and condensing the distillation vapor to form a distillate of a concentrated nitric acid solution, wherein the condensing step comprises cooling the distillation vapor formed in the distiller using a second portion of the solution as cooling medium, and absorbing the nitric acid mist contained in the gas.