Environmental Engineering Reference
In-Depth Information
Solid concentration measurements were performed with the standard IFRF solid
sampling probe. This technique requires measurements of both the mass of solid
collected in the filter (msolid,amb) and the dry volumetric flow rate (
V
gas,amb,dry
):
m
V
m
V
T
T
(
)
solid, flame
solid, amb
amb
C
=
=
1
−
X
solid
HO
2
gas, flame
gas, amb, dry
flame
where:
m
solid,flame
mass of the sampled solid in the flame
V
gas,amb,dry
dry volume of gas sampled in the flame at ambient temperature
T
amb
ambient temperature during the measurements
T
flame
flame temperature at the measured point
For every measured point:
T
flame
the measured in-flame temperature (
T
flame
~1600 K)
X
H
2
O
calculated from the measured gas composition (
X
H
2
O
~0.17)
T
amb
25˚C
The solid concentration measurements show a peak of 305 mg/m
3
at the coal
jet center line. These measurements were used to perform the analysis of the total
radiance measurements, as will be further discussed. The solid concentration in the
flue gas must be calculated in mg/ to enable comparison with legislation; the
formula to calculate the solid concentration in mg/
m
3
m
3
is as follows:
T
[
]
=
[
]
3
3
flame
C
mg m
C
mg m
soot
N
meas
273 15
.
m
3
The flue gas solid concentration was found around 1327 mg/ . In the HFO
flame the solid particle in the flue gas was estimated to be about 2400 mg/ . The
lower value in the coal flame may be explained considering the low ash content of
the coal and insufficient atomization in the HTAC98 trial.
m
3
2.5.3.4.7 Total Radiative Heat Flux
Figure 2.113
shows the total radiative heat flux for all four fuels, NG, LFO, HFO,
and coal. The heat flux profiles are very flat for all four fuels examined.
The heat flux values for the coal flame vary between 350 and 390 kW/m
2
and
the profile is very similar to that of the oil flame. The lower heat fluxes for light
fuel oil had already been discussed in the HTAC98 report.
The measured heat fluxes are high compared with the value in the normal com-
bustion system (~250 kW/m
2
for coal combustion and 150 kW/m
2
for NG combustion).
Enhancement in the heat fluxes characteristic of the high temperature air combustion
was observed in the coal flame as well but not in the same magnitude as in the NG
flame. The higher heat fluxes measured in the coal flames compared to the NG flame
are due to the presence of solid/soot particles. However, the radiative heat fluxes
measured in the coal flame were not much higher than in the NG flame (as it can be
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