Process for the production of chlorine dioxide

Claim 1

A process for the production of chlorine dioxide, chlorine, and an alkali metal salt which comprises: (A) separately feeding an alkali metal chlorate solution and a strong acid solution selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid and mixtures thereof into an integral forced circulation crystallizing reaction evaporator comprising, in vertical disposition: (a) an upper reaction crystallizing evaporation chamber having a substantially vertically disposed cylindrical partition which divides at least the lower portion of the reaction crystallizing evaporation chamber into a first and second substantially concentric cylindrical sections; (b) a heat exchange chamber comprising a multiplicity of vertically disposed tubular elements for transmission of fluids through said heat exchange chamber; and (c) a lower pump chamber, having an intake section and a discharge section and having a pump means disposed therein to provide forced circulation of liquid between the intake and discharge sections; (B) mixing the solutions therein and circulating the resultant reaction mixture, in response to the pump means, in sequence, from the discharge section of the lower pump chamber, upwardly through a first portion of the tubular elements, through the first cylindrical section of the upper reaction crystallizing evaporation chamber, over the cylindrical partition; downwardly through a second portion of tubular elements into the intake section and discharge section of the lower pump chamber; (C) maintaining the reaction mixture in sufficient volume to at least partially fill the evaporation chamber and provide a vapor-liquid separation space in the upper region thereof; (D) withdrawing an aqueous slurry of alkali metal salt of said acid from the circulating reaction mixture; (E) withdrawing chlorine dioxide, chlorine, and water vapor from the vapor liquid separation space of the upper reaction crystallizing evaporation chamber.