PuK - Process Technology & Components 2024

Compressors and Systems
Biogas backfeed
Biogas Backfeed in Leoben
Ralf Deichelmann
The best-known Austrian beer
brand on the global stage is Gösser
Bräu, owned by Brau Union Österreich
AG. And the brewery, located
in Leoben, Styria, has traditions
that date back more than 1000
years. In 1860, the brewer Max Kober
breathed new life into the brewery,
which had been started by the
nuns of Göss and later abandoned.
Nowadays, the green portion of the
logo also signifies the company's
commitment to a climate-friendly
business policy. Gösser is pulling out
all the stops to reduce its fossil fuel
consumption in production, procurement
and delivery. As well as rolling
out a large solar installation and
lever aging waste heat during the
brewing process, tapping into its own
biogas is one pillar of the company's
sustainability strategy.
In fact, the biogas supply is a joint project
between Brau Union, the energy
supplier Energienetze Steiermark
and the compressor specialist BAUER
KOMPRESSOREN. The biogas used in
the production process is extracted
from the brewery's spent grains, the
residue from the brewing process, in
Brau Union's own bio gas plant and
then transferred to “Energienetze
Steiermark” (Styrian Energy Networks),
which then converts the raw
gas into ready-to-use, compressed
and purified biomethane.
To ensure it is usable down the line,
the freshly extracted raw gas must
first be treated. It undergoes a process
called amine scrubbing, which
removes unwanted by-products from
the raw gas.
Fig. 1: The Gösser brewery uses biogas compressed by BAUER
Typical uses include to remove carbon
dioxide, hydrogen sulphide and
other acid gases from gas mixtures.
Amine scrubbing is based on the
chemisorption principle, which paves
the way for high purities, even at relatively
low pressures. The gas is only
under a few millibars of pressure
when it enters the feed system. Prior
to compression, the quality of the
processed biomethane is measured
with a gas analyser to determine the
methane content and its accompanying
substances and thus comply with
the benchmark values specified in
the relevant standards.
Fig. 2: Biogas recompressor station from BAUER KOMPRESSOREN as a containerised
solution for outdoor use
Two technically different compressor
systems were planned because
the power is fed into different grids
according to demand. And this is
where the cutting-edge compressor
technolo gy of natural gas and biogas
specialist BAUER KOMPRESSOREN
comes into play. The first of the two
systems uses a CNK9-55 water-cooled
screw compressor, which is designed
to deliver high capacity at low pres-
86 PROCESS TECHNOLOGY & COMPONENTS 2024