Combustion Phenomena of High Temperature Air Combustion - High Temperature Air Combustion: From Energy Conservation to Pollution Reduction - page 130

furnace, the emission behavior of volatile matter can be simulated. Under such
variable factors as the types of coal, the temperature of combustion air, and the
oxygen content, the oxygen ratio, tests are conducted by means of sampling and

Exhaust gas

Filter

to Gas anal y zers

Coal feeder

in
out

N 2 Cooling water

Air Air

Cooling water

Sampling port

in
out

Natural gas

Sampling probe

Window
Water cooled section

Air+O 2

120mm

Thermocouple Thermocouple

2108mm

FIGURE 2.95 Outline of horizontal reaction furnace of pulverized coal of high temperature
and high oxygen content.

analysis of reacting particles and gases and by optical measurement of instantaneous
particle temperature.
Figure 2.96 52 shows the changes of generated gas concentration and the average
temperature of particles and the reaction ratio of volatile matter (VM) and fixed
carbon (FC) in the direction of the center of furnace under the test conditions: the
kind of coal (WT coal); the air temperature (1300 K); the oxygen ratio (0.8); and
the oxygen content (21%). This figure shows that pulverized coal, when injected
into the furnace, abruptly emits volatile matter and burns, and according to the
elevating particles temperature, O 2 is consumed and CO 2 , CO, and H 2 are generated.
As shown in this figure, as abrupt emission of volatile matter occurs under such
high temperature reaction as these test conditions, we assumed the following rate
constant model (2.28) for quantitative evaluation of emission rate of volatile matter
from the ratio of remaining volatile matter in reacting particles obtained by the first
sampling port.

x
t

= k (2.28)

where x is the reaction ratio of volatile matter, t is the time, and k is the reaction
rate constant.

E
RT p

−

kk =

0 exp

(2.29)