Vacuum systems for extractive distillation

Extractive distillation methods are applied in the chemical and petrochemical industries as well as in general process engineering. Distillation takes place in distillation columns under optimum operating temperatures for processing and with this method under vacuum conditions. These processing techniques are also applied for the extraction of ultra-pure aromatic compounds such as, e.g., benzene from pressure-refined coking plant benzene.

Solvents of high polarity are used for the selective separation of aromatic and non-aromatic compounds dependent on the process. These solvents play an essential role in these process flows. Formylmorpholine (NFM) is used for this process and also as operating fluid for liquid ring vacuum pumps.


Vacuum systems are required in steel plants, coking plants, refineries, and re-distillation plants for the extraction and compression of various hydrocarbons such as aromatic compounds, naphthenes, olefins or paraffins. As a result of the debenzolisation of fuels, benzene is the finished product left in the distillation column. Whenever environmentally hazardous exhaust gases such as hydrocarbons or pollutants like sulphur, hydrogen sulphide occur in processing plants, such methods have to be used or added subsequently.


HERMETIC-Pumpen has supplied a total of 18 vacuum systems for these extractive distillation plants around the world since 1982. Further projects are in progress.

The vacuum systems are heated electrically and insulated and fitted with two HERMETIC vacuum pumps each and two HERMETIC canned motor circulation centrifugal pumps each. Components with an extraction capacity from 50 to 300 m³/h have been supplied so far, complete with canned motor drives as well as two major installations with an extraction capacity of 2000 m³/h and single mechanical seals. The extraction and compression pressures range from 50 mbar (abs) to 1200 mbar (abs).

Machines and equipment from HERMETIC are in use in India, Thailand, Poland, Taiwan, China, The Netherlands, Belgium, Hungary, Brazil, Saudi Arabia and Germany of course.

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