Environmental Engineering Reference
In-Depth Information
15.11
Amine scrubber plant (Copyright: Fraunhofer IWES).
amine solution in the absorption column in cross-flow. Unlike in pure
physical absorption, there is no flash column. The loaded absorption
chemical is regenerated in the desorption column, for which heat is needed.
Depending on the manufacturer and thus the used amine solution,
temperatures from 106 to 160
C are required in the desorption column
(flow temperatures before heat introduction have to be increased in each
case) [11, 12, 17, 20]. The product gas, which is saturated with moisture from
absorption, must be dried in a subsequent (normally adsorption) process.
Controllability in the range 50-100% (compared to nominal load) is
possible [11]. One technology provider reports controllabilities in the range
25-100% (compared to nominal load) [41].
Figure 15.10 describes the chemical absorption process (using organic
solvents) and an amine scrubber plant is shown in Fig. 15.11.
The electricity demand varies from 0.06 to 0.17 kWh
el
/m
n
3
related to raw
biogas [12, 19]. One plant manufacturer currently reaches warranty values
for electricity consumption of 0.09 kWh
el
/m
n
3
(for a methane concentration
of 65% in the raw biogas) and 0.11 kWh
el
/m
n
3
(for a methane concentration
of 55% in raw biogas) - both values correspond to product gas pressures of
50-150mbar and desorption temperatures of 135-145
8
C [17]. Another plant
manufacturer reports an electricity consumption of 0.17 kWh
el
/m
n
3
raw gas
for product gas pressures of 2.5 bar and water temperatures for the
desorption process in the range 120-130
8
C [12]. The heat demand for the
desorption process can vary from 0.4 to 0.8 kWh
th
/m
n
3
raw biogas [19]. One
plant manufacturer currently reaches warranty values for heat consumption
of 0.45 kWh
th
/m
n
3
(for a methane concentration of 65% in raw biogas) and
0.58 kWh
th
/m
n
3
(methane concentration of 55% raw biogas) and desorption
8
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