January 2019

Evonik Industries is expanding the capacity of one of its production plants.

During the manufacture of the products solvents are released. These solvents that are found in the waste gas of the production plant are to be recovered as far as possible and to be reduced from the waste gas before discharge to a further cleaning stage takes place.

For the solution to the problem posed by this task, Standardkessel Baumgarte GmbH is to supply a condensation plant based on the principle of direct condensation. A bath cooler unit was chosen that is designed for a condensation temperature of up to -20°C. The solvents are recovered 90% from the exhaust air and can be fed back to the production process. The residual solvent content in the clean gas meets the requirements for discharge to the further cleaning stage.

The condensation plant is a key unit for the new production plant, so that a high availability of the condensation plant is one of the most important requirements.

With the supply of the condensation plant and its integration into the process, Standardkessel Baumgarte GmbH will contribute to the successful increase in production.

The bath cooler is a direct contact device for intense heat and mass transfer.

The main design features of the bath cooler in detail are:

• Liquid as a cold accumulator bath, i.e. as a so-called liquid storage cooler.
• Introduction of the waste gas continuously via a gas distributor into the stored liquid. Gassing is carried out through a double perforated base plate, through which the gas flows.
• Intended pulsation on the double perforated base, hence avoidance of icing on the gas distributor.
• Rising gas bubbles convey liquid in their boundary layer from bottom to top. As a result, a forced circulation flow at the bath cooling wall is produced.
• Condensation of the solvents from the bubble column, i.e. from the gaseous phase through intense heat and mass transfer on the bubble boundary surface.
• Indirect cooling of the liquid bath (liquid storage cooler) by means of a heat exchange section immersed in the liquid, designed as a refrigerant evaporator.
• Collection of the accumulating condensate directly in the liquid bath.
• Filling-level controlled discharge of the condensate by means of a suitable liquid pump from a recirculation flow.

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