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Show DEMONSTRATED FUEL SAVINGS AND UNIFORM HEATING WITH 1000/0 OXYGEN BURNERS IN A CONTINUOUS STEEL REHEAT FURNACE Louise T. Walsh, Minda Ho, Maynard G. Ding Union Carbide Corporation Linde Division Tarrytown, New York, USA The LINDE "A" Burner System is a patented* oxygen-fuel combustion system developed for fuel savings and productivity increases in high temperature process furnaces such as soaking pits and batch or continuous reheating furnaces. The unique design of the burner enables the use of 100% oxygen in a wide variety of furnaces without creating a localized high temperature flame. This paper discusses the results of the first installation in a continuous steel reheat furnace. FUEL SAVINGS WITH OXYGEN When oxygen is used for combustion in place of air in high temperature process furnaces, significant fuel savings can be obtained due to the reduction in the sensible heat of the combustion products. Flue loss is usually the biggest single source of heat loss for high temperature furnaces. By replacing air with oxygen, the corresponding reduction of nitrogen lowers the flue volume by about 8 to 1 or more. As a result, the fuel savings using oxygen can be quite substantial. At a typical flue gas temperature of 2400 of for soaking pits or batch reheat furnaces, theoretical fuel savings with oxygen is 57% when replacing cold air and 31% when replacing air that has been preheated to 1000 of. In addition to flue gas temperature, fuel savings with oxygen also depends on the type of fuel used and the concentration of excess oxygen in the flue gas. The LINDE "A" Burner System has been installed in several industrial applications since 1980. In the steel industry, it has been *u.S. Patent No. 4,378,205; U.S. Patent No. 4,408,982; U.S. Patent No. 4,488,682; U.S . Patent No. 4,525,138; U.S. Patent No. 4,531,400; U. S. Patent No. 4,541,796; U.S. Patent No. 4,541,798 . 259 used in soaking pits, batch reheat furnaces and a continuous furnace using both natural gas and coke oven gas. A summary of these applications both steel and non-steel, and the fuel savings results are illustrated in Table 1. Table 1 - LINDE "A" Burner System Applications UN. "A" BU"N." 8YSTI!. ... SULTS '"0. ACTUAL OPERA'Tlotl FUEL SAVINGS UA" BURNER CONSUMPTlONS YEAR CUSTOMER FURNACE FUEL ClIo 1980 Crucible Betch NG 60 1980 Armco Soaking PIt NG 61 1982 U.S. Steel Betch Homestead Recuperative COG 44 1984 Inland 1985 U.S. Steel Gary· Soaking PIt COO 57 Continuous COO 52 1985 Kennecott Copper Anode NG 84 1985 Saint Ola .. Gobaln· Unit Malter NG 54 MMBtu{Ton 2.1 0.84 1.8 0.68 0.83 ......... _ ... ___0 1 __ 3.2 FUEL (MMBtu/Tonl 1.4 0.81 2.3 0.51 0.78 2.7 OXYGEN (TOM/Ton) 0.12 0.078 0.18 0.045 0.082 0.30 The first installation in a continuous steel reheating furnace took place in the 18-2 Bar Mill at U. S. Steel, Gary, Indiana in 1985. Two of the five fired zones were successfully converted to oxygen using the "All Burner Systems. The fuel consumption was reduced from 3.00 MMBTU/ton of steel to 2.16 MMBTU/ton of steel for a savings of 28%. The oxygen consumption was 0.062 ton 02/ton of steel which corresponds to 13.4 MMBTUs saved per ton of oxygen consumed. BENEFITS OF USING OXYGEN IN CONTINUOUS FURNACES There is a unique advantage in the use of oxygen in continuous furnaces as compared to batch type furnaces due to the counter-current operation which is typical of most continuous furnaces. In general, at a given production rate, fuel savings is achieved by either a |