Process Performance
A comparison between the performance of the Lurgi dry ash and the BGL gasifier is given in Table 5-5.
The much lower steam and somewhat lower oxygen consumption of the slagging gasifier result in a much higher syngas production per unit of coal intake and a much lower yield of pyrolysis products compared with the dry bottom unit. Further, the C02 content of the gas is lower and the methane content in the gas is halved.
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Table 5-5 Comparative Performance of Lurgi Dry Ash, BGL, and Ruhr 100 Gasifiers |
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Raw Gas Composition (Dry) |
Dry Ash Gasifier |
Slagging Gasifier |
Ruhr 100 90 Bar Carb. Gas |
Ruhr 100 90 Bar Clear Gas |
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C02, mol% |
30.89 |
3.46 |
29.52 |
35.47 |
|
CO, mol% |
15.18 |
54.96 |
18.15 |
17.20 |
|
H2, mol% |
42.15 |
31.54 |
35.11 |
39.13 |
|
CH4, mol% |
8.64 |
4.54 |
15.78 |
7.93 |
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CnHm, mol% |
0.79 |
0.48 |
1.02 |
0.04 |
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N2, mol% |
0.68 |
3.35 |
0.35 |
0.19 |
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H2S + COS, mol% |
1.31 |
1.31 |
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NH3, mol% |
0.36 |
0.36 |
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Feed components per |
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1000Nm3 CO+H2 |
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Coal maf, kg |
750 |
520 |
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Steam, kg |
1930 |
200 |
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Oxygen, Nm3 |
280 |
230 |
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kg pyrolysis |
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products/1000kg coal |
81 |
19 |
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Source: Supp 1990; Lohmann and Langhoff 1982 |
As mentioned above, the BGL gasifier has found a commercial application in waste gasification at the SVZ Schwarze Pumpe plant near Dresden in Germany. A 3.6m diameter BGL gasifier is fed with a mixed fuel of various wastes and coal. During test operation the unit has gasified a mixture of 25% hard coal, 45% refuse derived fuel (RDF) pellets, 10% plastic waste, 10% wood, and 10% tar sludge pellets.
During the performance test the following production and consumption figures were achieved (Greil etal. 2002):
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Mixed Fuel (ar) |
30 |
t/h |
|
Specific oxygen consumption |
<0.2 |
Nm3/Nm3 dry syngas |
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Gasification agent ratio steam/oxygen |
<1.0 |
kg/Nm3 dry syngas |
|
Raw syngas (dry) |
31,500 |
Nm3/h |
Gasification pressure is 25 bar. The ash content of the feed is discharged as a glassy frit. Analytical tests have demonstrated the nonleachability of the slag, and that disposal requirements, according to ТА Siedlungsabfall, class 1 (German waste regulations), have been met.