the coking properties of coal at elevated pressures. - Argonne ...

components of the limestone bed of run 2481 changed as follows: CaO decreased by 1
dilution to 37% by the coal ash; SO3 increased to 28% by adsorption; and Na20
increased to 7.7% of the bed. Si02, A1203, Fez03 and MgO remained constant
throughout the run after the initial eight hours.
The concentrations of alumina and silica remain constant during the run
indicating that the aluminosilicate clay particles leave the bed during combustion.
On the other hand, the calcium oxide and sodium oxide which largely originate from
the organic structure of the lignite are free to react with the SO2 and bed material
increasing their concentration.
OXIDE A
Si02 10.76
A1203 11.70
FeO 4.82
MgO 5.71
CaO 18.11
Na20 12.70
so3 34.45
TABLE 3. CHEMICAL ANALYSIS DATA FOR FIGURE 1 TO 11.
WT. %
OXIDE H I
B
12.45
11.20
0.55
1 .I4
32.86
3.99
37.25
Si02 15.50 19.66
A1203 10.28 0.15
FeO 0.75 0.37
MgO 3.84 0.09
CaO 40.45 53.36
Na20 1.91 1.74
so3 21.49 24.39
C D
8.22 12.16
18.94 8.94
6.94 3.02
11.86 5.73
12.63 12.83
10.14 17.97
30.80 38.27
E F G
31 .EO 47.80 48.32
19.13 10.03 10.61
13.14 9.95 9.48
10.27 4.44 6.26
19.82 20.28 20.29
2.04 6.11 3.73
3.39 0.43 0.52
J K L M
12.39 1.81 0.89 31.50
5.13 5.91 1.87 8.20
1.15 0.32 81.69 0.56
0.93 0.17 0.91 0.00
44.23 39.58 13.55 44.19
0.78 0.40 0.00 2.76
35.37 51.66 6.33 11.89
CONCLUSIONS I
Agglomeration of the bed material can be manifested in many different ways
depending on the chemical composition of the bed. The elements which have a ma-
jor effect are sodium, calcium and sulfur which react with the bed material possibly
forming possibly a molten phase. This phase causes other ash constituents to ad-
here to the bed particles. As this phenomenon reoccurs many times, agglomeration
becomes more severe.
REFERENCE
1. Goblirsch, G.M., Vander Molen, R.H., and Hajicek, D.R., AFBC Testing of
North Dakota Lignite, Sixth International Fluidized Bed Conference, Atlanta,
Georgia, April, 1980.
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