de - Beste verfügbare Techniken (BVT) - Umweltbundesamt

6.2 Process intensification
Description
Chapter 6
Most OFCs are manufactured in batch stirred vessels, which are used for blending, reaction and
separation (eg crystallisation, liquid-liquid extraction). Such technology has the benefit of being
well understood and highly flexible. However, as described in Section 6.1, performance is often
suboptimal. Even when mixing in stirred vessels is optimised, fundamental limitations on their
performance (e.g. rate of mixing and heat transfer) can still mean loss of performance on scale
up (see Section 6.1).
Moving from batch to small scale, continuous, intensified reactor technologies has the potential
to make step changes in environmental performance. A wide range of such Process
Intensification (PI) technologies is available for single and multiphase processes, including:
• static mixer reactors
• ejectors
• combined chemical reactor-heat-exchangers (HEX reactors)
• spinning disk reactors
• oscillatory flow reactors
• ‘higee’ technology.
PI technologies are complementary to microreactor technologies (Section 4.1.4.6), and can be
applied where larger production rates are required (10 – 10000 tonnes per year) and the
‘numbering up’ philosophy for microreactors becomes impractical.
Achieved environmental benefits
These will vary from application to application, but typical examples of environmental benefits
from the application of PI are:
• 99 % reduction in impurity levels in a hydrosilylation process resulting in a more valuable
product whilst reducing excess reagents by around 20 % and removing requirements for an
additional solvent
• >70 % reduction in energy usage (typical figure for a range of processes studied – achieved
through substantial reduction in the time spent mixing and the ability to integrate heat)
• >99 % reduction in reactor volume for potentially hazardous processes, leading to
inherently safe operations.
Maximum environmental benefits can be achieved through combination of PI with green
chemistry (Section 4.1.1), solvent selection (Section 4.1.3), and alternative synthesis and
reaction conditions (Section 4.1.4).
Cross-media effects
Wahrscheinlich keine.
Operational data
Some additional development time may be needed for an intensified, continuous process, and
care is needed with start up and shut down procedures. Once operating under steady state
conditions, such technologies will provide reliable processes, with minimal manual
interventions required and batch to batch variability avoided.
OFC_BREF Dezember 2005 397