Environmental Engineering Reference
In-Depth Information
This would result in greater influence upon the oxygen content in the furnace.
Therefore, the diameter of the hole for inserting the nozzle was made close to the
diameter of the nozzle. The gap was designed to be covered by a heat insulating
material by filling it in at the same time as the nozzle was inserted.
2.4.1.2 Experimental Method
2.4.1.2.1 Air Preheating
A heat exchanger of a high-speed switching type with a generative system was used
to heat the air and to generate the high temperature preheated air. The air preheating
method is as follows. First, the air is drawn in by a blower. The drawn-in air passes
through the directional control valve on the left side facing the furnace to be
measured (as shown in Figure 2.1 ) . It then passes through the heat reservoir in the
furnace to be measured, which by this time has become cooled. The air that has
passed through the heat reservoir in the furnace to be measured is then heated by
both the pilot burner and the heat-up burner.
The heated air enters the furnace on the right side as shown in the test section
of combustion chamber shown in Figure 2.1. Then, the heated air passes through
the cool heat reservoir on the right side as shown in the figure. At this time, the
valves of both the pilot burner and the heat-up burner are closed.
When the heated air passes through the heat reservoir, which is cool, a heat
exchange is carried out between the heated air and the heat reservoir, heating up the
cooled heat reservoir. After exchanging the heat, the air passes through the directional
control valve and then is discharged by the blower as waste gas. The above-mentioned
process is defined as half cycle, and this is carried out continuously for about 20 s.
After completing a half cycle, the directional control valve is switched to the
direction of the right side of the furnace. The supplied air passes through the heat
reservoir on the right side, which has already exchanged the heat to be heated, and
is further heated by both the pilot burner and the heat-up burner. The drawn-in air
is heated by exchanging the heat with the heat reservoir and by both the pilot burner
and the heat-up burner.
The heated air enters the furnace to be measured, and passes through the heat
reservoir to exchange the heat. The air having been heat-exchanged passes through
the directional control valve to be discharged. After completing this process, the
directional control valve is switched. This half cycle is carried out repeatedly to heat
the air.
Experimental conditions for carrying out tests are shown in Table 2.7 . The
expression of the oxygen content is as follows:
(
)
Air
Air + Nitrogen
Oxygen = 0.21
(
)
Here, Oxygen is the volumetric content of oxygen, Air is the volumetric flow
rate of air, and Nitrogen is the volumetric flow rate of nitrogen. In the present
 
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