de - Beste verfügbare Techniken (BVT) - Umweltbundesamt

Chapter 2
2.3.7 Recovery/abatement of exhaust gases
[15, Köppke, 2000]; [31, European Commission, 2003], *019A,I*
Figure 2.6 gives an overview of the recovery/abatement techniques applied to exhaust gases.
Oxidisers include thermal and catalytic oxidation. The choice of a particular technique or a
particular combination of techniques depends on the contaminants present and especially on the
VOC concentration, flow and the variations in concentration and flow. Additionally, various
types of filters can be used to recover particulates.
Events of planned or emergency shutdowns may require back-up systems or modifications of
schedules and hours of operation.
Primary and secondary condensers (non-cryogenic) are directly attached to the reactors. If VOC
rich exhaust gases are treated by thermal oxidation, other streams can be used as the oxygen
source, e.g. VOC lean or odorous streams.
Thermal oxidisers and incinerators
In this document, the term “thermal oxidation” is used where applied to the gas phase, however,
where co-treatment of gas, liquids and/or solids is carried out, then “incineration” is used.
The gas collection system consists of the source enclosure, vents and pipes. The gas flowrate is
minimised by encasing the source as far as feasible. Explosion risks are controlled by the
installation of flammability detectors inside the collection system and by keeping the gas
mixture securely below the lower explosion limit (“LEL”, usually below 25 % LEL), above the
higher explosion limit or by inertisation.
Waste gas
containing
VOC and
possibly other
pollutants
Selection of
techniques or
combinations of
techniques based
on pollutant
concentration,
flow and the
variations in
concentration
and flow
Thermal
oxidiser
DeNO x
Particulate
removal
Other
pollutants,
no VOC Scrubber
Cryogenic
Condenser
Adsorber
Condenser
Waste gas
emission
Figure 2.6: Typically applied recovery/abatement techniques for exhaust gases on OFC sites
30 Dezember 2005 OFC_BREF
Scrubber
Scrubber