Agriculture Reference
In-Depth Information
Table 11. Emissions comparison from Coal and Coal-PP blends
NO
x
(mg/Nm
3
at 6% O
2
)
SO
2
(mg/Nm
3
at 6% O
2
)
Thoresby coal
1600 - 1800
2500 - 2750
70/30 blend
1200 - 1600
1600 - 2400
60/40 blend
1200 - 1500
1000 - 1500
50/50 blend
1200 - 1500
500 - 1000
A comprehensive discussion on the emissions from the combustion sugar industry by-
products is given in the following paragraphs.
Emissions data for NO
x
and SO
2
for coal-pulp blends is summarised in Table 11. The
normalised NO
x
emissions at 6% O
2
for coal-pulp blends are compared with those for coal
alone in Figure 4. NO
x
emissions for blends are only 12 - 22% lower than those for coal
although “as received” nitrogen content of pulp (0.14%) is considerably lower as compared to
1.62% for the coal. However, the dry matter contribution of pulp in the blends is very low as
compared to coal. Thus coal nitrogen plays a dominant role in the formation of NO
x
due to its
higher mass contribution. Nitrogen conversion for the blends is between 26% and 32% which
is almost the same as that for coal as mentioned previously. As emissions of NO
x
for blends
are lower than coal a further benefit of co-firing pressed pulp should be a reduction in NO
x
emissions.
Emissions of SO
2
in mg/Nm
3
corrected to 6% O
2
for coal and coal-pressed pulp blends
are shown in Figure 5. The figure shows that SO
2
emissions for blends are lower than those
for coal. Although the data is scattered nevertheless it is clear that the emissions decrease with
increase in proportion of pressed pulp in blend. Based on the sulphur content of the blends,
most of the data corresponds to a sulphur conversion of 40% - 60%, 26% - 40% and 14% -
27% for 70/30, 60/40 and 50/50 coal-PP blends, respectively, see Figure 6.
3000
2500
2000
Thoresby coal
60/40 coal/PP
50/50 coal/PP
70/30 Coal/PP
1500
1000
500
0
700
740
780
820
860
900
940
Bed Temperature (
⁰
C)
Figure 5. Comparison of SO
2
emissions from coal and coal-PP blends
.
