I.R.I.S. FLAME MONITORING SYSTEM P522 - Manual (Page 16)

IRIS MODEL P522 APPLICATION MANUAL
Page 16
SETUP AND ADJUSTMENT
PROCEDURES
Multiburner applications require the most care in
adjustments to ensure proper flame out operation
under worst-case conditions (refer to previous sec-
tion MULTIBURNER REQUIREMENTS).
These same procedures can be followed for single-
burner applications, even though the adjustment re-
finements described here may not be necessary.
There are two, basic worst-case conditions in a
multiburner installation:
One is the initial light off of other burners
after the first burner has been established
(particularly if the established burner, or
burners, has a flame envelope that over-
laps the trial burner sighting). If there is a
flame out or ignition failure of this burner
(or its igniter) during this startup sequence,
the flame monitor must detect this condi-
tion – meaning that it must discriminate
between the lack of flame and the back-
ground flame of the established burner.
This would represent “flame discrimina-
tion under low fire conditions.”
Second would be when the fired unit is in
a high fire condition (i.e., all burners are
firing at maximum rate, when suddenly
one burner flames out – possibly because
of a clogged oil gun or some other type of
fuel disruption). This is also a dangerous
condition, particularly for two- to four-
burner installations. The flame monitor
must detect this flamed out burner so the
fuel valve (safety shutoff valve) supply-
ing this burner will close. This means that
the flame OFF threshold for this flame
monitor must be set above the signal level
produced by the other burners that are in a
high-fire condition.
SIGHTING ADJUSTMENT
Before making definitive settings (i.e., establishing
the set points) for flame ON/OFF, you must opti-
mize the sighting of the viewing head. This can be
done if a swivel joint is used at the end of the sight
pipe and the diameter of the sight pipe is large enough
to allow a range of angles to be viewed (see section
ANGLE OF VIEW OF VIEWING HEAD).
As a general rule, the sighting of the S506 viewing
head is more likely to be “line-of-sight” than the S512
infrared flicker viewing head, which will read flame
signals bouncing off the side of the sight pipe and
other “reflectors.” Sometimes, the reading with the
IR detectors can be greater with a reflective signal
than the direct line of sight. The UV viewing head,
on the other hand, will have to be aimed at the part
of flame having the highest concentration of UV
which is usually at the root of the flame (at the throat
of the burner) and in a very narrow range.
The angle of view of the S506 is somewhat wider
than the S512 or S509, but this does not offset the
fact that the UV radiation present is very narrow.
This is not true, however, for low NOx gas burners;
the UV is usually much less in intensity with this
type of burner, and spreads out in front of the burner,
getting readings from all over the furnace when many
burners are on. This is particularly true when fuel
gas recirculation is used.
Another factor to consider when aiming the viewing
heads is the load condition of the boiler. The flames
from a burner can be radically varied at different
loads – one of the reasons for trying to select a sight-
ing that will minimize the changing flame at differ-
ent loads. If the flame front moves farther away at
higher loads, then a sighting parallel to the burner
axis will be best. A large-diameter sight pipe with a
swivel mount is recommended for all installations
on large, multiburner boilers. (Refer to Figure 20.)
INITIAL SETUP
A. The initial settings for the P522 signal
processor should be as follows:
1. F.F.R.T. (Time Delay Off) to 3 SEC.
2. GAIN SET to 25.
3. TIME DELAY ON to 0.
4. FLAME ON to 200.
5. FLAME OFF to 100.