Proceedings World Bioenergy 2010

into the adsorber (more information see table II), either
straightly or indirectly making a detour through a gas
heater. Within the adsorber, which is filled with the
adsorbent Diaion WA21J, adsorption of the gas takes
place. Not adsorbed gas leaves the adsorber and is
analyzed with regard to its composition and concentration
by an NDIR-analyzer (non-dispersive infrared).
Inside the adsorber, a tube bundle is placed providing
the possibility of water passing through. Water which is
let through the tubes can either be cold or warm. In this
way, the adsorbent is cooled or warmed indirectly. In
case of cooling, adsorption time is prolonged due to
Figure 2: Flow sheet of laboratory test rig
6 EXPERIMENTAL
TSA experiments focused on investigating the
process step of desorption. In order to desorb a saturated
adsorbent, it has to be heated up whereas for heating
different ways are available. On the one hand, heating
can be carried out directly, i.e. with preheated gas passing
through the adsorber. On the other hand, heating can be
done indirectly, i.e. by heat exchange with hot water. In
the course of the experiments three ways of desorption
were tested
• desorption by indirect heating with hot water
• desorption by indirect heating with hot water
and afterwards purging (with N 2)
• desorption by indirect heating with hot water
and simultaneous direct heating with purge gas
(N 2).
All TSA process experiments followed a certain
procedure. During the process step of adsorption a binary
gas mixture containing methane and carbon dioxide was
applied. Thereby, carbon dioxide and small amounts of
methane were adsorbed while methane passed through
and left the adsorber. Moreover, during the adsorption
step cold water was applied in order to prolong
adsorption time by dissipating heat deriving from the
actual adsorption process. At the moment when carbon
dioxide breakthrough occurred, application of the binary
gas mixture was stopped and the process was switched
from adsorption to desorption. During the process step of
desorption the adsorbent was heated up in one of the
ways mentioned above. The heating let to desorption of
the adsorbed carbon dioxide and methane. Desorption
was stopped when neither methane nor carbon dioxide
were detected in the gas analyzer placed after the
keeping the adsorbent at low temperatures by dissipating
adsorption heat. Warm water is applied for the process
step of desorption.
Table II: Adsorber dimensions
Height 1000 mm
Inner diameter 41,4 mm
Outer diameter 46 mm
Material Borosilicate glass
adsorber. After desorption, the adsorbent was cooled
down to ambient temperatures with cold water and then a
new cycle including adsorption, desorption and cooling
was carried out. One entire TSA process experiment
consisted of five cycles, each cycle including adsorption,
desorption and cooling.
In table III all test parameters are given.
Table III: Test parameters
Adsorption
Gas mixture 65% CH 4, 35% CO 2
Gas flow rate 2.2 Nl/min
Water temperature approx. 10°C
Desorption
Water temperature 75°C
Purge gas N 2
Purge gas temperature 75°C
Purge gas flow rate 25 Nl/min
7 RESULTS
Results obtained from the TSA process experiments
carried out in the laboratory test rig are described in the
subsections below.
Figures depicted in these subsections show only the
first cycle of each TSA process experiment. The
temperature illustrated in these figures presents the
temperature in the middle of the adsorber.
7.1 Desorption by indirect heating with hot water
Figure 3 shows the TSA process with desorption
carried out by indirect heating with hot water.
During the adsorption step the binary gas mixture fed
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