Blast Furnace: R&D Trends
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Adapted from: Agarwal, J.C. et al, 1994, “Natural Gas Injection into Blast Furnaces: Operating Practice Update” |
Equipment
Combustion Technology
Energy Consumption
Process Description
R&D Trends
The blast furnace operation is one of the most capital intensive processes within the integrated steel industry. It requires associated coke production or imports which have become increasingly difficult and expensive due to stringent environmental requirements. In the long run, researchers are working on entirely new “cokeless” production techniques as described in the section on Direct Reduction, R&D. In the near term, the aim of blast furnace R&D is to reduce coke consumption and to increase productivity of the furnace.
In North America, in an effort to reduce emissions, coke consumption has been on the decline. From roughly 1988 through 1994, the average blast furnace coke consumption decreased by 140 pounds per ton of hot metal (lb/thm), fuel injection increased by 47 lb/thm, while furnace productivity has risen by 25%. Blast furnace operators are injecting supplemental fuels such as natural gas, pulverized coal, heavy fuel oil, coking tars, and pitches.
GRI is supporting the demonstration of very high levels of natural gas injection. Half of the blast furnaces operating today in the U.S. now use natural gas injection, some now use injection rates as high as 260 lb/thm. The focus of the GRI R&D program is to demonstrate the benefits of these higher injection rates and to develop new control strategies that will optimize furnace operation at these high rates of natural gas injection. Full scale tests of various injection rates were conducted at the #3 blast furnace at Armco Steel’s Middletown works in 1991 by Charles River Associates. The results of the preliminary work show productivity increases of 8% and coke reductions of 1.30 to 1.36 pounds of coke per pound of natural gas injected. In addition, proper control strategies were demonstrated.
Pulverized coal injection (PCI) is also being demonstrated on a smaller number of high volume blast furnaces. PCI has an operating cost advantage when compared to gas injection, but it entails a much higher capital cost and it requires high volume, steady state operation making it unsuitable for furnace campaigns that require flexibility and load following.
Hogan, W.T., 1994, “Steel in the 21st Century”. Competition forges a New World Order”, Lexington Books (MacMillan), New York, 1994.
Agarwal, J.C. et al, 1994, “Natural Gas Injection into Blast Furnaces: Operating Practice Update”, Charles River Associates, Inc. GRI Report No. GRI-94/0405.