Environmental Engineering Reference
In-Depth Information
Table 6 Scaled-up simulations based on increasing the coal feeding rate
Test no.
Input
Output
m
s
(kg/h)
m
coal
(g/h)
v
n2
(L
N
/h)
v
air
(L
N
/h)
Power
(W)
CO
2
,
FR
(vol. %)
O
2
,
FR
(vol. %)
O
2
,
AR
(vol. %)
Base case
9
256
186
1980
1591.4
62.67
0.69
4.95
Scale-up 1
18
512
372
3960
3182.8
62.67
0.69
4.95
Scale-up 2
27
768
558
5940
4774.2
62.67
0.69
4.95
Scale-up 3
36
1024
744
7920
6365.6
62.67
0.69
4.95
Scale-up 4
45
1280
930
9900
7957
62.67
0.69
4.95
unchanged for the scaled-up simulations. The total thermal power output and main
gas compositions for the
flue stream from the air reactor and the fuel reactor are
summarized in Table
6
. It can be seen that the total power output increases linearly
with increase in coal feeding; however, the
fl
flue stream composition remains steady
for all the scaled-up simulations. Considering the principles of energy and mass
balance on which ASPEN Plus modeling is based, linearity in the scaled-up results
is expected since nonlinear effects such as the energy losses at multiple locations are
inherently omitted in the modeling process.
fl
3.4 Simulations of CLOU Process Using Different Types
of Coal
It is also important to test the performance of a CLOU system for various types of
coal. Three different types of coal are used with the Cu
60
AlMg oxygen carrier:
bituminous Colombian coal
anthracite coal from El Bierzo, and
lignite coal from Teruel basin (Abad et al.
2012
). The selections of these coal
samples are based on the consideration of diversity in their volatile matter content
and carbon content since it is of great interest to investigate the performance of
CLOU process over a wide range of coal properties. Therefore, samples from three
different coal ranks, bituminous, anthracitic, and lignite are considered in this
modeling. The detailed properties of these coals are summarized in Table
7
.
Process simulations for various types of coal are conducted for different coal
feeding rates. The CO
2
concentration in the
“
El Cerrejon,
”
flue stream of the fuel reactor outlet and
the overall energy released are compared in Fig.
8
a, b, respectively. For all three
types of coal, the
fl
ue stream CO
2
concentrations and the power outputs increase
with the higher coal feeding rate as well as with the higher carbon content in the
coal. Since the carbon content of bituminous coal and anthracite coal is similar, the
results for these two types of coal show similar characteristics for the CO
2
con-
centration in the
fl
flue stream and in the overall power output. In contrast, lowest
CO
2
concentration in the
fl
flue stream and least power output are obtained for the
lignite coal due to its low carbon content. Overall, characteristics of the CO
2
fl
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