1. Introduction - Firenze University Press

1
opt(N
eTG
) k O2 K T
opt(N
eTG
)
k 1 R
kl
g , (10)
42
opt(N
eTG
In the (8) optimal compressor pressure ratio ( k ) is determined in the same way as for a
kl
classic gas turbine. Calculated optimal compressor pressure ratio values, due to generated electricity
from the turbine set are gathered in Table 2.
Table 2. The optimal compressor pressure ratio values, due to generated electricity from turbine set
Name Symbol Value
The oxygen recovery rate R, % 50 70 90
Optimal compressor pressure ratio k_ASUopt, -
for ASU
Optimal compressor pressure ratio
for TG
k_T Gopt, -
)
6.4 5.8 5.3
7.8 7.8 7.8
The optimal compressor pressure ratio values, due to the gross efficiency as well as for the
autonomous gas turbine depends on the optimal compressor pressure ratio values, due to electricity
opt(N
)
generated from the turbine set ( k
eTG ) and the gross efficiency of the electricity generation of
the unit ( elTG ). The relationship between these quantities is as follows:
opt(
eTG
)
k
opt(N ) 1
K
T
eTG k
1 elTG
, (11)
mK
1
delTG
Equation (11) was determined using (3), (5) and (7), with the condition 0
d
.
Figure 7 shows a graph of gross efficiency of electricity generation as a function of the compressor
pressure ratio for the two different oxygen recovery rates in the air separation unit (50% and 90%)
and for autonomous gas turbine.
Gross efficiency of gas turbine, %
40
36
32
28
24
20
16
12
8
4
0
-4
-8
-12
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Air compressor preassure ratio, -
Fig. 7. Gross efficiency of both units as a function of compressor pressure ratio for two different
oxygen recovery rate
k