Role of hydrogen in blast furnaces to improve productivity and decrease coke consumption

Abstract

The hydrogen contained in blast furnace gases exerts a variety of physical, thermochemical, and kinetic effects as the gases pass through the various zones. The hydrogen is derived from two sources: (1) the dissociation of moisture in the blast air (ambient and injected with hot blast), and (2) the release from partial combustion of supplemental fuels (including moisture in atomizing water, steam, or transport air, if any). With each atom of oxygen (or carbon), the molar amounts of hydrogen released are more than six times higher for natural gas than for coal, and two times higher for natural gas than for oil. Injection of natural gas in a blast furnace is not a new process. Small amounts of natural gas--about 50--80 lb or 1,100--1,700 SCF/ton of hot metal--have been injected in many of the North American blast furnaces since the early 1960s, with excellent operating results. What is new, however, is a batter understanding of how natural gas reacts in the blast furnace and how natural gas and appropriate quantities of oxygen can be used to increase the driving rate or combustion rate of carbon (coke) in the blast furnace without causing hanging furnace and operating problems. The paper discussesmore » the factors limiting blast furnace productivity and how H{sub 2} and O{sub 2} can increase productivity.« less