Patent ID: 8163092

Claim:
A method for producing a concentrated HCl vapor from a super azeotropic aqueous solution of HCl, the method comprising the steps of: (a) introducing an aqueous feed to an evaporation chamber containing a mother liquor, said aqueous feed containing at least 10% sugar, on a weight basis, of sugar within said feed to sugar and water within said feed, and having an HCl concentration of at least 18%, by weight, said concentration defined by a relationship: C liq =100 ·A /( A+W ) wherein: C liq is said concentration by weight, expressed in %; A is a weight percent of HCl in said aqueous feed, and W is a weight percent of water in said aqueous feed; (b) directly contacting said mother liquor with a heat transfer fluid in a heat-laden state, to transfer heat from said fluid, whereby HCl is evaporated within said chamber, to produce the concentrated HCl vapor and to produce said mother liquor, said mother liquor including said heat transfer fluid in a heat-depleted state, with respect to said heat-laden state, and an HCl-depleted aqueous phase having a reduced concentration of HCl, with respect to said HCl concentration; (c) subjecting a first portion of said mother liquor to a liquid-liquid separation to produce a first aqueous liquid phase containing HCl, and a second liquid phase containing said heat transfer fluid in said heat-depleted state; (d) heating said heat transfer fluid in said heat-depleted state, to regenerate said heat transfer fluid in said heat-laden state, and (e) returning said heat transfer fluid in said heat-laden state to step (b), wherein associated with said evaporation chamber is a circulation loop, having a first end and a second end disposed in fluid communication with said evaporation chamber, wherein a second portion of said mother liquor, containing said HCl-depleted aqueous phase and said heat transfer fluid in said heat-depleted state, is circulated through said loop as a circulated mother liquor; and wherein said contacting of said mother liquor with said heat transfer fluid in said heat-laden state transpires within said circulation loop.