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Show AFRC90 Paper 18 NOx REDUCTION WITH OXYGEN-FUEL COMBUSTION ABSTRACT C.E. Baukal and A.I. Dalton Air Products and Chemicals, Inc. Allentown, PA The minerals, metals, and waste incineration industries rely heavily on combustion for materials processing. These industries are being forced to upgrade their current combustion technology since increasingly stringent regulations are being written to limit NOx production. There are different strategies for reducing NOx. The more expensive strategy post-treats the flue gas to remove NOx after its formation. The less expensive method is to minimize NOx formation in the flame using combustion modification techniques. However, this often also reduces combustion efficiency. Oxygenfuel combustion is a modification technique that not only lowers NOx but also increases efficiency. Air Products conducted an extensive set of experiments in a large scale instrumented furnace to compare the NOx emissions from both air-fuel and oxygen-fuel burners under controlled conditions. The oxygen-fuel burners produced an order of magnitude less NOx than the air-fuel burners. For both the air-fuel and oxygen-fuel burners, NOx was a strong function of the oxygen level in the oxidizer and of the stoichiometry. The paper discusses the lab results and shows how NOx is affected by the various parameters. Implementation of oxygen-fuel combustion technology has produced dramatic NOx reductions while actually increasing efficiency compared to previously employed air-fuel systems. Examples of NOx in specific applications are presented. INTRODUCTION NOx has been shown to cause smog, acid rain, ozone depletion and global warming. New environmental legislation is continually being passed for tighter NOx emissions. There are two strategies for handling NOx. The first strategy is post treatment of the flue gases to remove NOx after its formation, such as the Exxon thermal deNOx process. These methods can be capital intensive and usually require stopping production if anything goes wrong with the treatment equipment. The second strategy is to prevent NOx from forming in the flame by modifying the combustion process in some way. Several methods include flue gas recirculation, staged combustion, and water injection. These methods are usually less capital intensive but may reduce combustion efficiency. The paper presents a better alternative for controlling NOx by using oxygen, instead of air, for combustion. By drastically reducing the nitrogen content in the system, NOx can be minimized 1990 AFRC Symposium -1- October 1990 |