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BCU 460, BCU 465 · Edition 11.19
36
Low NOx mode (flameless operation)
5 Low NO
x
mode (flameless operation)
Low NOx mode leads to a significant reduction in ther-
mal NO
x
formation in ON/OFF-controlled high-velocity
burners.
5 .1 System structure and function
The system consists of a burner BIC..M with system
components tailored to the application. The system
components make it possible to operate the burner in
two operating modes: conventional Flame mode at low
furnace temperatures and Low NO
x
mode with flame-
less combustion at high furnace temperatures.
VAD
BIC..M
IC 40 + BVH
M
VAS..L
VMV
DG
BCU 465..D2
PZL
Process Control (PCC)
AKT
STM
A burner BIC..M in conjunction with a burner control
unit BCU..D2 is required for safe burner operation in
Low NO
x
mode.
The gas and air for Flame mode and Low NO
x
mode are sup-
plied via the same connections. The gas pressure upstream
of the burner is adjusted using a pressure regulator (e.g.
VAD). The gas volume is set using a fine-adjusting valve
(e.g. VMV). The air volume for the operating modes is set by
adjusting the butterfly valve (e.g. BVH). The air pressure is
monitored on each burner by a pressure switch to check the
functioning of the butterfly valve.
In addition, air/gas ratio
monitoring for the zone or the furnace is required since
the air pressure switch is not sufficient for use as a low air
pressure protection device .
The menox
®
burner BIC..M has a special mixing unit
whose geometric design ensures reliable ignition and
a stable flame while also making sure that the flame-
less combustion process is transferred to the furnace
chamber.
In Flameless mode, the inflammable gas/air mixture
must be prevented from igniting prematurely in the
ceramic combustion chamber each time the burner is
switched on. The flow velocity at the burner nozzle must
be adequately high to prevent the danger of flashback in-
to the combustion chamber. Burners BIC..M are tailored
to the appropriate capacity and combined with tapered
ceramic tubes (TSC..M).
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