Honeywell C7015A manual Flame has been extinguished, Sighting Summary, 760-2306-5

RESPONSE TO HOT REFRACTORY

Although the infrared amplifier will not respond to steady radiation, as produced by hot refractory, be careful to protect the infrared detector from hot refractory radiation because of two possible conditions, shimmer and raa’iation saturation. a. Shimmer-Turbulent hot air, steam, smoke, or fuel spray in the combustion chamber can reflect, bend, or block the steady infrared radiation emitted by a hot refractory. These conditions can change the steady radiation from a hot refractory into a fluctuating radia- tion. If these fluctuations occur at the same frequency as that of a flickering flame, they will simulate flame and will hold in the flame relay after the actual burner

flame has been extinguished.

b. Radiation saturation--Steady hot refractory radiation can become strong enough to mask the fluctuating radiation of the flame. This is similar to the effect of holdingupacandleinfrontofthesun-thelightofthe sun is so strong that the candle light cannot be seen. If radiation saturation is extreme, the flame relay will drop out, and the system will shut down as though a flame failure has occurred.

Both of these problems will be minimized by aiming the detector at a portion of the refractory that is:

•as cool as possible.

•as far from the cell as possible.

•as small as possible reduce the field of view, see Figs.

2and3.

Refractory temperatures in the combustion chamber will vary with combustion chamber design but generally, the end wall of the chamber will be the hottest point. It will normally be best to aim the detector at the side wall of the refractory (Fig. 4), at a point above the refractory (Fig. 5), or at the floor of the combustion chamber (Fig. 6).

SIGHTING SUMMARY

When sighting the detector, two important factors to consider are: (1) proper sighting of the flame being detected (normally the pilot/main Rame junction), and (2) avoiding hot refractory sighting.

A typical sighting arrangement is shown in Fig. 4. The detector is aimed at the intersection of the pilot and main flames, and at a relatively cool side of the combustion chamber. The detector, in this case, would be located as close as possible to the burner to sight the maximum depth of the &me and reduce the effect of variations in the main flame pattern.

The detector can also be sighted from a point below and close to the burner with the line-of-sight above the refractory (Fig. 5).

The third method is to aim the detector from above the burner, sighting a portion of the refractory floor (Fig. 6). This type of application requires that the pilot flame be carefully sighted from the side. The detector should not be sighted over the shoulder of the pilot because the chances increase of sighting a pilot too small to satisfactorily light the main flame,

Theactualareaofhotrel?actorysightedshouldbeassmall as possible and consistent with proper sighting of the flame. Refer to Figs. 2 and 3 for methods of reducing the ama of hot refractory sighted.

C7015A

INSTALLATION

Fig. 4--C7015A infrared Flame Detector aimed at side wall of combustion chamber.

MAIN BURNER FLAME

- - - -

	_-	--
			I
\		AREA VIEWED BY C7015A ’ , ,
	I		‘Y
\
. .	I		_/-- _--
	‘, I	__-----	M245,

Fig. 5-C7015A Infrared Flame Detector aimed at a point above refractory.

				/ ,l‘-		DETECTOf3 VIEWS AREA
BURNER		/				--__I ABOVE THE REFRACTORY
FACEPLATE					I	&ii -
	/ /					/cd - -
I	--_				! // - ----‘n
cr
I	P;- +--/___ _.=’ i
i-1			i&
	-7
					PILOT AND MAIN FLAME
	\ \						. . . .
								1-J
		\ .			I		_/--
					I	_M--
				\			M305.3
					\L_----

Fig. 6-C7015A Infrared Flame Detector aimed at floor of combustion chamber.

	,	,‘P--__	--__
, / ,		I		--__
		I			-3.
				.’ 1

CENTER LINE

\REFRACTORY FLOOR

’\ AREA VIEWED BY C701

\\ I___------,,,

\L_---

760-2306-5