REVERSE ANNULUS COMBUSTION
Th
e 4748 is a unique low NOx, high effi
ciency single ended
radiant tube burner. Unlike conventional SERT burners,
combustion occurs in the annulus formed between the outer
radiant tube and the inner fl ue tube. Combustion gases then
turn 180° to reverse through the inner fl ue tube to the integral
high effi
ciency heat exchanger having a return gas fl ow path
to conventional SERT burners; hence the name Reverse Annulus
Single Ended Radiant Tube burner, or "RASERT."
The 4748 RASERT has a number of advantages over
conventional SERTs. Since the fl ame is in direct contact with
the inside surface of the radiant tube, heat is transferred to
the furnace more effi
ciently. The fl ame propagates outside the
combustion tube rather than inside, resulting in less thermal
stress on the combustion tube. RASERT is a patented design
(#6,321,743) of the Gas Technology Institute (GTI) developed in
collaboration with North American.
BURNER CAPACITY
The 4748-650 is available in one size. The minimum radiant
tube inside diameter for this burner is noted in Table 1 below.
Air capacities will be higher when starting the burner in a
cold environment. Air fl ow will decrease as fl ue gases and
tube temperatures increase. See page 3 for a detailed graph
showing fl ue gas oxygen levels
vs.
radiant tube temperature.
Furnace temperatures may cause slight variations in burner
capacity. Page 4 has further information on radiant tube sizing
.
Radiant
Tube
Burner
inside
diameter
designation
1 osi
4 osi
9 osi
16 osi
inches
4748-650
425
850
1300
1750
6.50 - 7.38
Air Capacity (scfh at 1650 F furnace temperature)
with burner air supply pressure of
Table 1
Table 1
—
Low NOx, CO and CO
2
emissions achieved by effi cient
staged combustion, and integral fl ue gas recirculation
—
Compatible with many existing control systems including
simple cross-connected regulator systems
—
Built-in air/fuel metering and gas limiting orifi ce valve mean
easier installation and commissioning
—
Direct spark ignition
THE 4748 RASERT
™
ADVANTAGE:
FLUE OUTLET
FUEL IN
COMBUSTION AIR IN
PRIMAR
Y AIR / FUEL
RETURNED FLUE PRODUCTS
ANNULAR COMBUSTION ZONE
SECONDARY AIR
Bulletin 4748
Page 2
Product Overview | Rasert™