Page 81 - Boiler plant and distribution system optimization manual

66 Boiler Plant and Distribution System Optimization Manual

on which is in use. The volume change, percent
CO or O , can be read in percent on a convenient
2
2
scale.

FINDING STACK LOSSES

By measuring the net stack temperature
(Stack temperature—combustion air tempera-
ture), combustion tables or slide rule (Figure 7.9)
can be used to determine flue gas losses.

Measuring Flue gas Oxygen on a
Continuous Basis
There are three common methods of measur-
ing oxygen in flue gas on a continuous basis. The
paramagnetic sensor, the wet electrochemical cell
Figure 7.7—Fyrite CO or O indicator and the zirconium oxide ceramic cell.
2
2
these gases. They are a very practical, simple,
rugged and economical approach to combus-
tion testing. Also, they are very
useful for backing-up the more
complex instruments which
may develop errors and faults
from time to time.
To operate the Fyrite O
2
and CO indicators, a flue gas
2
sample is extracted from an ap-
propriate point, using the hand
operated sampling assembly.
The rubber cap is placed over
a spring loaded plunger valve
which opens when pressure is
applied (Figure 7.8). The aspi-
rator rubber bulb is squeezed
about 18 times in succession to
clear the sampling apparatus,
insuring an undiluted flue gas
sample. When the plunger is
released, the flue gas sample is
trapped in the instrument.
The FYRITE is now invert-
ed twice, thoroughly mixing the
flue gas sample with the chem-
ical reagents which absorb of Figure 7.8—Use of the Fyrite illustrated for testing for carbon dioxide
either the O or CO , depending (CO ) and Oxygen (O )
2
2
2
2