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Show INTRODUCTION Heat treatment of metals in industrial furnaces demands a high temperature uniformity and controllable atmospheres. The best device for this application is a radiant tube burner due to the combustion process inside the tube which allows for a uniform tube surface temperature and controllable atmosphere around the load (1,2). Butane, and butane/propane mixed vapor is the basic industrial fuel in Asian countries and is becoming popular in some European countries. Butane vapor characteristics are significantly different from natural gas. For example, the heat capacity of butane is 3.2 times more than for natural gas, the specific gravity is 3.0 times more, combustion temperature is much higher, and soot release intensity from pre-heated butane vapor is much stronger. Due to this, it is impossible to operate Radiant Tube burners with natural gas nozzles on butane vapor with acceptable temperature uniformity and emissions output. Typical issues for those tests would be high emission levels, high smoke index numbers, and flame instability (3) Eclipse Combustion, Inc. Single-Ended and u-type radiant tube firing burners on natural gas, operate effectively and reliably worldwide. The Company initiated the program to modernize these burners with fuel switching from natural gas to butane. This paper describes the performance obtained for radiant tube burners with butane in comparison with natural gas and propane combustion resulting from the development of new nozzles, that can be simply replaced when the fuel is switched. DEVELOPMENT OF BUTANE NOZZLES A specially designed butane storage and delivery system has been installed for butane vapor to the pilot scale furnace. A -2- |