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Process technology for exhaust air purification

Exhaust air purification - separation of solvents
Evonik, Singapore

Exhaust air purification

Separation of solvents
Evonik, Singapore

Technical Data Reference Sheet


For high solvent concentrations in the waste gas from a production plant a suitable separation process is to be used for the separation of the solvents. As a function of the emitting process the waste gas contains, depending on the production step, different methanol and methyl methacrylate concentrations. The waste gas is to be cleaned to the required emission limit values. The solvents are to be recovered as a valuable resource. The solvents are then to be available in the liquid form for further use.



For recovery and separation of the solvents direct condensation in a liquid storage cooler is provided as a thermal separation process. The means of dissolving is the bath cooler - an item of direct-contact process equipment, in which the waste gas is brought into direct contact with the liquid bath. In this case it is a bubble column in which the evaporator package cools down the liquid to be found in the tank. The liquid corresponds to the composition of the condensate from the waste gas stream. The waste gas stream to be condensed is fed out via a gas distributor as a perforated plate, passed into the tank and conveyed through the liquid storage tank as a bubble column with the help of a fan. The waste gas containing solvent cools down in the bubble column to the temperature set in the storage tank which is below the dew point of the compounds. The condensate forming is collected directly in the liquid. The liquid storage cooler is kept constantly at the selected condensation temperature. The solvent concentration at the outlet from the system corresponds to the saturation concentration of the solvent used.


For more information, please see our reference sheet.

"The purification of waste gases and process gases is increasingly becoming a core issue in the design of plants due to the increasing environmental requirements. With our processes, we can not only clean the gases, but also make the ingredients available for recycling."

Annette Ziemann-Nöthe

Deputy Head of Exhaust Air and 
Exhaust Gas Cleaning

Technical Data

Number of Lines


Exhaust Air Flow

10 - 60 m³/h i. N.

Exhaust Air Temperature

min10 °C

max60 °C

Separation of


Condensation Temperature

min.-40 °C

max.-30 °C

Operating Pressure

abs.0,9 bar

Condensation Capacity

bis10,7 KW

Solvent Concentration Methanol

min.60 g/m³ i. N.

max.220 g/m³ i. N.

Solvent Concentration Methyl methacrylate

min.100 g/m³ i. N.

max.280 g/m³ i. N.

Control Range Volume Flow

0 - 100 %

Operating Mode




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