Prepared discussion read by C. M. Stendhal (U.S.A.).
The results of the various phases of the API Oil Burner research program described by the authors were not intended to be finished burners ready for commercial application. Considerable development is still required to reach this stage. It is being done, and is there progress along these lines which can be discussed? Which of these approaches studied by the API shows the most promise? Do the authors know whether consideration is being given to combining the different phases of the API work? Are combination vaporizing-recirculation or recirculation-ultrasonic burners being investigated; and what advantages might be gained by making such combinations ? Also, what attributes must a new burner possess if it is to displace a considerable fraction of the high pressure burners now in use ? In the area of residual fuel combustion, we expect to see a number of improved burners applying the Ijmuiden studies, despite the slightly higher combustion air pressure they require. These burners should reduce considerably the volume required for combustion and will be most valuable in package boilers. In very large boilers, the limitation on size is more apt to be the heat transfer surface requirement.
Regarding the use of low excess air combustion, the major remaining problem is that no readily applicable means has been developed for achieving satisfactory combustion at 1 per cent excess air in existing boilers.
Where this level has been reached, it has usually been the result of intensive effort and revised instrumentation. As a result, there has been a growing trend toward the combination of operating at moderately low excess air levels, around 5 per cent, and using a small amount of alkaline earth additives.
With regard to air pollution, we feel that it will be necessary to find ways to burn petroleum fuels with no emission of pollutants in the future. Currently, the emphasis is on reducing emission of SOp. We can count on increasing pressure to reduce particulates, nitrogen aromatics. If we are unable to solve these problems, the almost inevitable result will be a premature switch to nuclear power generation.
J. A. BOLT (U.S.A.): Regarding further development from the API program, at least three manufacturers in the U.S.A. are working on recirculating burners, and interest is very high. Battelle has developed small ultrasonic burners for U.S. military applications, and more are being ordered.
There is also an ultrasonic atomizer burner, developed in Germany by Dr. Pohlmann which appears promising, in which the atomizer is used in both, to lift the fuel