Environmental Engineering Reference
In-Depth Information
Fig. 13 Variation of
γ
with
Φ
/
Φ
LBO
for high air flow rate
175 LPM for different
premixing lengths (L
fuel
).
Shown method is capable to
detect LBO in high flow rate
(Chaudhari et al.
2013
)
premixing. The Reynolds numbers for which the technique is tested and discussed
above are low compared to the actual
fl
low condition in practical gas turbine system.
In order to check the ef
cacy of the current LBO detection technique in high
fl
ow
regime, experiments has been carried out where we used Q
air
= 175 LPM and
ow
rate is tested for all premixing lengths allowed by the design of premixing tube.
Figure
13
plots the variation of
fl
for equivalence ratio normalized by its value at
γ
LBO limit (i.e.,
/
Φ
LBO
) for all the allowable L
fuel
and with
fixed air
fl
ow rate (Q
air
)
Ф
175 LPM.
The trend obtained for
flow rate for different premixing lengths is quite
satisfactory and matches with the earlier observed trend of low
in high
fl
γ
fl
low rate. This
proves that the
flame color-based LBO detecting technique consistently works
satisfactorily over a wide range of
fl
ow rates.
All the experiments discussed above are carried out with fuel (LPG: 60 %
propane, 40 % butane). The proposed method works satisfactorily and can be
implemented with active control system for early detection of incipient LBO.
However, natural gas is a common fuel in practical gas turbine system. In order to
check the ef
fl
cacy of the proposed LBO predictor, methane is used as fuel. We
tested high
flow rate 200 LPM on 3 different premixing lengths. Figure
14
shows
the variation of
fl
reported over normalized equivalence ratio (i.e.,
/
Φ
LBO
). From
γ
Ф
the plot, it is observed that the
cantly drops near LBO and matches with the
earlier trend observed in LPG fuel. Moreover, the values of the metrics also match
closely for the two fuels. This proves that the proposed LBO detection technique
can satisfactorily monitor the proximity of LBO in con
signi
γ
guration of high
fl
flow with
methane fuel which is common con
guration used in practical gas turbine.
The previously discussed conventional LBO detecting techniques are highly
dependent on the extent of fuel/air premixing, and they need a sample length (N)to
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