Development of injection of reduction gas into the blast ... - klimazwei

3. Results of theoretical approach
For a first determination of penetration depth CFD calculations were carried out by
using the commercial FLUENT software. The calculated percentage of reducing
gas in the shaft for an injection velocity of about 170 m/s is shown in figure 6 as an
example. In a distance of 790 mm from the shaft wall the percentage of reducing
gas decreases to 50 %.
Figure 6: calculated percentage of reducing gas in the shaft
Table 2 shows the results of thermochemical equilibrium calculations for the
product gas formed by partial oxidation of natural gas with oxygen. The resulting
ratio between H2 and CO amounts approx. 2. The reducing gas contains about 5.6
% of total oxidised components CO2 and H2O.
set points:
reducing gas flow [Nm 3 /h) 2,400
reducing gas temperature [°C] 900
input:
natural gas flow [Nm 3 /h] 800
oyxgen flow [Nm 3 /h] 470
reducing gas composition:
H2 [Vol.-%] 61.7
CO [Vol.-%] 31.8
CO2 [Vol.-%] 1.5
CH4 [Vol.-%] 0.5
N2 [Vol.-%] 0.4
H2O [Vol.-%] 4.1
Table 2: results of thermochemical equilibrium calculations for the product gas
4. Operational results and obtained experience
After commissioning the 4 HGG at BF 1 a trial period of approx. 6,500 h was
started. The penetration depth of the injected hot reducing gas into the shaft was
measured by He-tracing experiments by using the natural He-content of the
injected natural gas (250 to 300 ppm). During reducing gas injection gas sampling
is done via 6 channel above burden probe at the top of the shaft (27.3 m above BF
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