MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...

2.5x10 -4
2 /sec)
2.0
1.5
Rate (g/cm
1.0
0.5
0.0
0.0
2.5x10 -4
2 /sec)
2.0
1.5
Rate (g/cm
1.0
0.5
0.0
0.0
2.5x10 -4
2 /sec)
2.0
1.5
Rate (g/cm
1.0
0.5
0.0
a)
c)
e)
0.5 1.0
Gas Velocity (m/sec)
2.0
4.0
Total Pressure (atm)
6
8
Particle Size (mm)
1.5
6.0
10
2.5x10 -4
2 /sec)
2.0
1.5
Rate (g/cm
1.0
0.5
103
b)
0.0
0.00 0.05 0.10 0.15
Oxygen Partial Pressure (atm)
2.5x10 -4
2 /sec)
2.0
1.5
Rate (g/cm
1.0
0.5
0.0
0.0
2.5x10 -4
2 /sec)
2.0
1.5
Rate (g/cm
1.0
0.5
0.0
1000
d)
2.0 4.0
Total Pressure (atm)
1100 1200
Gas Temperature (K)
Figure 7.4. Comparison of the HP-CBK predictions of reaction rate with large coal
char particle data (Mathias, 1992) as a function of a) V g, b) P O2 (P tot = 0.85
atm), c) P tot (x O2 = 21%), d) P tot (P O2 = 0.18 atm), e) d p, f) T g.
Pulverized Char Drop-Tube Data
Monson (1992) conducted char oxidation experiments on a 70-μm Utah coal char
at total pressures of 1, 5, 10, and 15 atm. Chars were prepared in the HPCP furnace in a
nitrogen environment at atmospheric pressure, wall and gas temperatures of 1500 K, and
a residence time of 300 ms. In the char oxidation experiments, reactor temperatures were
f )
0.20
6.0
1300