Raschig Rings for Regenerative Thermal Oxidizers

Regenerative thermal oxidizers (RTO) are widely employed by chemical, petrochemical and pharmaceutical plants to effectively destroy volatile organic compounds (VOCs) and harmful air pollutants. Most RTO systems utilize Christy Fill honeycombs or T-99 ceramic media beds to capture waste heat generated by combustion while preheating combustion air for efficiency.

RTO stands for Reversible Thermal Oxidation process, and involves the reversible separation of phenols and cresols using fractional distillation. In the past, these chemicals were separated through batch distillation using tall columns which consumed both time and energy to operate. To increase yield and purity of his products, Dr. Fritz Raschig sought an efficient method of dividing them. His initial attempt involved filling a distillation column with wine bottlenecks; however these proved problematic with column performance due to shattering glass necks shattering throughout.

Raschig rings have quickly become one of the most widely-used random packing materials for distillation. These tubular pieces shaped like saddles with ridged surfaces provide additional surface area for mixing and interaction between condensed material and vapor, creating moderate amounts of theoretical plates while having low hold-up pressure loss, making these rings ideal for distilling viscous materials without flooding issues or clogging issues.

The present invention concerns a regenerative thermal oxidizer system comprising three separate heat transfer columns 16, 18 and 20 that are in fluid flow communication with a combustion chamber 12. A contaminated vapor stream first passes through the first column where it undergoes preheating through heat exchange with hot combusted steam before being diverted to the second one for cooling by heat exchange with hot combusted steam from column one.