I. INTRODUCTION
The development of efficient, low polluting combustion
systems is a major goal of combustion
researchers and the manufacturers of combustion
equipment. To meet that goal, a good collaboration
of basic researchers and design engineers, with the
transfer of knowledge from theory and practice in
both directions is necessary. For the benefit of energy
resources and the environment, it is necessary that the
new combustion systems are accepted and used in the
industry. That requires, among other things, an
affordable price and it must be possible to operate
these systems without special expertise.
Nitric oxide could be ranked to the most relevant
pollutants, which is even emitted if 'clean gases' like
natural gas or hydrogen are used because it can be
formed from air nitrogen and oxygen at high
temperatures. Within the last years, great progress
has been made to reduce nitric oxide, or more general
NOx-emissions, from combustion systems. The use of
catalytic converters for the internal combustion
engines of automobiles are law in many nations
now. Today, nearly every burner manufacturer offers
low-NOx (and even ultra-low-NO . . . . . ) burners, but
there is still a great potential for the reduction of
pollutants.
Beside energy shortage, which is not perceived by
many people, the influence of combustion products
on the global climate had become a catchword in the
discussion about the combustion of fossil fuels.
Although these different arguments for reducing the
energy consumption, the clear task of engineers is the
development of efficient combustion systems.
Especially at high temperature processes, better
efficiency is mostly achieved by air preheating.
Therefore, energy of high temperature exhaust gases
is transferred to the combustion air in recuperative or
regenerative heat exchangers. A consequence of high
air preheat temperatures are increased peak temperatures
in the flame with an enormous effect on the
thermal NO-formation. The target is to overcome the
conflict of interest between energy savings and NOreductions.
A new technical form of combustion,