Environmental Engineering Reference
In-Depth Information
tages: it can be applied most easily from the viewpoint of devices in a laboratory
environment and nozzle clogging caused by the carbonizing of the fuel through an
oxygen-free thermal decomposition in the high temperature air rarely occurs. In any
case, the spraying pressure exerts a wide influence upon the diameter of liquid
particles to be obtained.
With the purposes of easily controlling the spraying pressure and of obtaining
a stable pressure, a method of accumulating the pressure to an accumulator was
adopted in the present experiment. The accumulator was used instead of a pressure
tank, filled with kerosene, and was pressurized by a high pressure air tank arranged
on top of the accumulator. By adopting this pressurizing method, the time required
for accumulating pressure using a device such as a pressurizing pump can be
eliminated, and the necessary stable pressure can be obtained by simply controlling
the opening of the regulator.
The nozzle is inserted in the hole on the right side facing the furnace to be
measured. It may take a little longer, because the capping of the hole arranged on
the furnace is tightly closed because it would be dangerous if the hole opened during
the course of raising the temperature. Then the pressure of the spraying device is
raised to the level of experimental conditions, and immediately after sliding the
nozzle to secure it in the spraying position in the furnace, the valve is opened to
start measuring without delay. Great care should be taken in this procedure.
2.4.1.2.4 Measurement of Flame
For investigating the characteristics of the flame, a digital camera was fixed in front
of the furnace on a tripod to take photographs of the flame. To eliminate any
background luminescence, it was necessary that the physical relationship between
the furnace and the camera should be fixed during testing. However, this practice
was not carried out in the present experiment.
The photographs of the flame were taken at intervals of 50˚C in the combustible
temperature range from 1100 to 250˚C. However, since some time was required for
inserting the nozzle and diluting the air, the temperature fell slightly during these
operations. Therefore, the in-furnace temperature was raised to 1200˚C to carry out
such measuring practices in time, and then the measuring was done. The falling rate
of the in-furnace temperature changed with every experiment due to such factors as
the warming-up state of the furnace. Therefore, in the present experiment, the
warming-up operation of the furnace to be measured was fully carried out before
measuring.
Further, the in-furnace wall surface was designed to be covered by a thick heat-
insulating material, so that the wall temperature was the same as the diluted air
temperature. Therefore, it was assured that there would be no influence caused by
the dispersion of the wall temperature, when measuring the flame in the process of
its self-cooling.
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