Untersuchungen des Gichtstaubes zur Steuerung des Kohlenstaubeinblasens in den Hochofen

Geyer, Richard W.; Senk, Dieter (Thesis advisor); Schmöle, Klaus Peter (Thesis advisor); Wotruba, Hermann (Thesis advisor)

Düren : Shaker (2023)
Book, Dissertation / PhD Thesis

In: Berichte aus dem Institut für Eisenhüttenkunde 1/2023
Page(s)/Article-Nr.: 183 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2022

Abstract

Steel is one of the most requested materials worldwide and the production process carries with it a sizable ecological footprint. With steel being responsible for about 7% of the CO2 emissions in Germany, iron and steel industries must find innovative solutions to control their ecological impact. There is much that can be achieved via science and research to optimize the production process and improve overall efficiency with regards to energy, emissions and costs. The emphasis of this thesis is to discuss methods which can be used to improve the process of pulverized coal injection into blast furnaces. During this process, pulverized coal can be partially transformed into carbon monoxide within the blast furnace, acting as a substitute reducing agent for the more expensive traditional coke. The remaining part of the pulverized coal that has not or not fully been transformed, known as "char", will exit the furnace within its gas stream via the risers and finally arrive at the respective cleaning aggregates. Measuring the quantity of actual char that has inadvertently entered the gas stream can be used to enhance the efficiency of the blast furnace process. However, identifying and quantifying specific char particles is challenging due to the presence of multiple carbon phases, including coke rubber and soot, which co-exist in the gas stream. While distinguishing these particles chemically is not possible, the following pages develop a combined method consisting of optical classification by both general and scanning electron microscopy, as well as thermogravimetric analysis. This combined method would allow for initial classification of the carbon phases by their visible characteristics (as cataloged in a database), with subsequent validation of the results by thermogravimetry. This method has been successfully tested across multiple samples taken from different furnaces. In addition, a correlation was identified between the amounts of char and coke within the gas stream, and the measured the blow rate. Even though relatively small samples have been used to this point, the measurement deviations were found to be insignificant. In conclusion, this proposed combined method is a valuable tool for optimizing the pulverized coal injection of the blast furnace process and shows high potential to develop a sustained method of operation across the blast furnace process. This thesis covers the general development and testing phase of the proposed combined method and how to implement it using a variety of analytic and physical techniques. With the local measurement of the chemical composition being an interest, an in-situ measurement system was created to continuously determine the particle composition. The system is based upon laser-induced-breakdown spectroscopy, both stationary and integrated (with the integrated system capable of operating within the furnace). Testing showed that the stationary operation allowed positive results referencing iron- and carbon analysis. Meanwhile, the integrated and continuous application was being tested towards its capabilities by simulating and modelling the behavior of certain particles within the gas stream. Testing ultimately determined that the integrated "LIBS-system" was not operating successfully under given conditions. Additional experiments would be required to determine if different types of lasers, like fan lasers, could improve the integrated system results.

Institutions

• Division of Materials Science and Engineering [520000]
• Chair of Metallurgy of Iron and Steel [522310]