Environmental Engineering Reference
In-Depth Information
Table 15.2 Solubility in cm
n
3
/(g bar) of selected gases at 258C in tetraethylene
glycol dimethyl ether (Genosorb
®
1753) [40]
CH
4
CO
2
H
2
S
NH
3
O
2
H
2
SO
2
0.2
3.1
21
14.6
0.2
0.03
280
Genosorb
®
scrubber plant (Copyright: Fraunhofer IWES).
15.9
condensation of water, which can be diverted from the system [13]. The
applied operation temperature in the absorption column is 10-20
C [13].
The design and operation of an organic solvent scrubber are comparable to
the water scrubber. As in the water scrubber, no precision desulphurization
is usually required. The product gas, dehydrated due to the hygroscopic
properties of the absorption agent and desulphurized, leaves the column at
its top. Depending on the target specifications of the product gas and the
composition of the raw gas, another precision desulphurization step can
follow and/or the product gas is dried by adsorption. As in water scrubbers,
the saturated washing solution is partly expanded in a flash column. The
desorbed gas is recirculated. To achieve reduced methane losses in the
system, two flash columns can also be used [14]. Complete desorption is
achieved by heat (approx. 40-80
8
C) and stripping air in the desorption
column [11, 14]. Current operation temperatures in desorption columns are
in the range 40
8
C and can be provided by heat uncoupling (heat
exchanger/cooling after compression and/or off-gas treatment) without any
external heat source [14]. Flow variations in the range 50-100% of the
nominal load are possible [11].
The electricity demand varies from 0.23 to 0.33 kWh
el
/m
n
3
raw biogas [11,
8
C-50
8
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