Evaporation apparatus of special material

Abstract

An evaporation apparatus for use in the evaporation, concentration, and/or purification of solutions containing alkali metal hydroxides and alkali metal chlorides, which apparatus has a liquid receiving chamber for the solutions being processed, a flow-through heating zone containing heat transfer elements, a separation chamber for forming a liquid-vapor mixture of the solution being processed, passageways connecting said chambers and said zones, and baffle and distribution means positioned within said chambers, zones and/or passageways, the improvement which comprises forming at least a portion of those surfaces of the said heat transfer elements, chambers, zones, passageways, baffle and distribution means of said apparatus which are in contact with the solution of said alkali metal hydroxide and said alkali metal chloride at temperatures in excess of about 50.degree. C of a ferritic stainless steel having the following composition: Carbon Up to 0.01% by weight Manganese Up to 0.40% by weight Phosphorus Up to 0.02% by weight Sulfur Up to 0.02% by weight Silicon Up to 0.40% by weight Nitrogen Up to 0.015% by weight Copper Up to 0.20% by weight Nickel + copper Up to 0.50% by weight Chromium 25.0 to 27.5% by weight Molybdenum 0.75 to 1.50% by weight Iron Balance

Dependencies are inferred from the claim text.