Agriculture Reference
In-Depth Information
Table 25. Gas analyses of the Coal-Vinasse test
Coal
only
Coal +
V
inasse
Gas constituent
As measured
(12.7% O
2
)
Corrected
to 6% O
2
As measured
(10.3% O
2
)
Corrected
to 6% O
2
CO
2
(%)
6.3
11.4
8.1
11.4
CO (ppm)
350
633
2234
3132
NO
x
(ppm)
472
853
471
660
SO
2
(ppm)
443
801
711
997
(a) Site of interest 1
(b) Site of interest 2
Figure 17. SEM scan of coal-vinasse agglomeration test.
presence of water or is absorbed by water. The same phenomenon was observed during coal-
PP pulp tests. The nitrogen content of vinasse was also very high, but the NO
x
emissions were
the same (on as measured basis) before and after the introduction of vinasse, but were found
lower in the latter case when corrected to 6% O
2
basis. This could be because N in biomass
behaves differently than N in coal as discussed previously.
5.4. Co-Firing of Pressed Pulp with Coal
Vinasse and raffinate agglomeration tests revealed that agglomeration occurred fairly
quickly and could be problematic in fluidized beds. Consequently, it was decided to perform
prolonged tests in which pressed pulp, having relatively lower alkali content, was co-fired
with coal to assess its behaviour in the bed. The test rig was operated at a typical bed
temperature of about 870°C for approximately 7 hours per day for 11 days to assess the
likelihood of agglomeration over a longer term when co-firing coal and pressed sugar beet
pulp. Before the co-firing tests with coal and pulp, the rig was fired with Thoresby coal for 3
days for comparison purposes and after replacement of the bed the remainder of the tests were
undertaken with a 50/50 blend of coal and pulp. Samples were removed from the bed on a
daily basis for SEM analysis. Results of SEM analysis of representative samples are given in
Table 26. There was no evidence of abnormal fluidized bed behaviour during these tests.
Moreover visual and microscopic examination exhibited no visible signs of
agglomeration, see for example Figure 18 which presents a magnified image (SEM scan) of
