Blast Furnace Coal Injection Trial Results Using Granulated and Pulverized High Volatile Coal

INTRODUCTION This report presents the results of two trials conducted with the Blast Furnace Granular Coal Injection System at Bethlehem Steel Corporation's Bums Harbor Plant. The trials were conducted using granulated and pulverized high volatile coal from Colorado. The first trial was conducted to quantify the effect that a high volatile western coal, Colorado Oxbow, has on the blast furnace operation and the process economics compared to the eastern low volatile coal that is the current standard at Bums Harbor. The high volatile western coal was pulverized for the second trial. The pulverized trial period is compared to the granular period using the high volatile coal and analyzed for blast furnace process differences. The first trial, the comparison of high to low volatile coal, is an important aspect of the demonstration project. This trial shows the role that coal chemistry, specifically carbon and ash content, has on the blast furnace process. The objective of the second trial was to determine if injected coal size, i.e., pulverized versus granulated, has an impact on blast' furnace performance. This comparison of pulverized versus granulated coal was an important part of the demonstration project. The design phase was conducted in 1991-1993. The design of this coal injection system, especially the coal grinding mills, make it possible to pulverize as well as granulate coal for furnace injection. BACKGROUND The granulated coal injection facility at the Bums Harbor Plant began operation in January 1995. Coal injection began on D furnace in mid-December 1994, primarily to test the coal grinding and preparation circuits. Significant operations began January 19, 1995 when coal was injected through four tuyeres at a total rate of 20 pounds/NTHM. Coal injection was initiated on C furnace on February 9, 1995 using four tuyeres at an overall rate of 25 pounds/NTHM. The remaining 24 tuyeres used natural gas injection at the same time. These conditions were maintained throughout February and March. 1 Complete coal injection began on D furnace in April 1995 and on C in June i995. Since that time the operation has progressed steadily and culminated in the development of efficient operating practices using the granulated coal facility. During the start of coal injection, Sydney coal, a high volatile eastern coal, was used on both furnaces for eight months. Subsequently, six different low volatile coals were used on both furnaces for seven months. The low volatile coals performed well and led to …