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Sizing of Packed Towers in Acid Plants

PACKING DESCRIPTIONS

The highly corrosive nature of sulfuric acid has restricted the materials that can be used economically in acid plants to ceramics.  In the pioneering days of the industry, quartz rock or crushed brick were often used in packed towers.  In due course these packings, which are very inefficient, were replaced by ceramic Raschig rings and by grid tile.  The author has had personal experience with a situation where one tower with quartz rock was still found to be in operation while the others were filled with three inch cross-partition rings.   Ceramic Pall Rings were also used in early days, but soon ceramic saddles became the industry standard.  Originally 1.5" saddles were used, followed later by 2" saddles, and finally by 3" saddles.  Recently, CECEBE introduced the HP^TM Saddle Packing, which has more open structure and, therefore, has a much lower pressure drop with greater capacity.  It is made of much stronger porcelain which has less tendency to form chips.  Structured Ceramic Packing and Wave Packing have been introduced by other suppliers and design techniques need to be disclosed for these new packings.  Surprisingly, the actual performance of the standard 3" saddle in a large tower also remains to be firmed up.

Physical Factors

By: Gordon M. Cameron (CECEBE Technologies) and Ian Chang (NORAM Engineering)