(190c) Material Selection for Packed Columns in the Chlorine Drying Stage of the Chlor-Alkali Process

The Chlor-alkali industry uses electrolytic processes to produce chlorine and caustic soda from aqueous sodium chloride solutions. Chlorine drying is one of the stages of chlorine processing which removes moisture from chlorine by using sulfuric acid. Two or more columns are employed in series for chlorine drying by counter-current contact of gas flow with acid flow in a packed column. For the latter, material selection is pivotal to the process design because even small traces of water in chlorine can be highly corrosive. Water content in chlorine and sulfuric acid drive the material selection, which in turn is dependent on each material’s chemical resistance, temperature rating, mechanical strength and cost. Design and economic considerations that lead to selecting materials for the column shell, internals and high capacity random packing are discussed in this paper. Quantitative comparisons of the different packing materials in terms of their hydraulic properties will be shown. This will be supported using select commercial application examples.