Features

The EtO scrubbing system is based on absorption of ethylene oxide and its subsequent hydration to ethylene glycol. Reaction rate is a function of temperature in the presence of a catalyst, typically sulfuric acid. Energy consumption is minimal.

Contaminants Removed

• H2S , HCl , HF , HBr
• HCN ,HNO3 , NH3
• Formic acid , Chromic acid
• SO2 , Cl2, F2, Br2 , BCl3, BF3
• Formaldehyde , Ethylene compounds
• Soluble alcohols, acids
• VOCs And many others

Mechanism

The EtO scrubbing system is based on absorption of ethylene oxide and its subsequent hydration to ethylene glycol. Reaction rate is a function of temperature in the presence of a catalyst, typically sulfuric acid. Energy consumption is minimal. The final product of a system is an ethylene glycol solution containing a small amount of acid. In cases where no discharge can be tolerated, calcium hydroxide can be added to the solution to precipitate the acid as calcium sulfate, leaving a solution of 30 weight percent neutral ethylene glycol.

The heart of the system is a counter flow packed column where the initial absorption takes place. As shown in the diagram above, EtO gas enters at the bottom of the column, and flows upward through the packing while the scrubbing liquid flows downward by gravity. In the process, intimate mixing and absorption of the gas takes place. The liquid carries the absorbed gas into the reaction vessel or sump, which is designed to allow sufficient residence time for complete conversion of EtO to ethylene glycol.

In most installations, the size of the column is based on total gas rate to be handled and column height may vary with required efficiency. Most columns are quite high – 25 feet or more – with diameters from 4 to 12″. Height is seldom a problem, however, because outdoor installation (as shown above) or installation where the column projects through the roof, is perfectly feasible. Since the end product of the cycle is an ethylene glycol solution – common antifreeze – only minimal insulation will be required for a successful outdoor or semi-outdoor installation.

Advantages

• Can sustain highly corrosive atmosphere.
• Relatively low pressure drop.
• High mass transfer efficiency.
• Require relatively small space.

Applications

• Landfill and Biogas Contaminants
• Acid Fumes and gases
• Chemical Fumes and Odor
• Food Processing Odors
• Metal Finishing Fumes
• Steel Processing Fumes
• Wastewater treatment plant odors