Thesis for the Degree of Master of Science


Year 2004
Matias Majaharju

Development of Measuring System for Profile of Pellet Bed

The object of this thesis was to develop a reliable, accurate and ease calibrated measuring system prototype for pellet bed height profile. The measured profile average controls the speed of the steel belt, which carries the pellet bed in the furnace. Profile measuring is very important for the sintering process, because the thickness of the pellet bed directly affects the functionality of the process and the longevity of the steel belt.

The literary part of this thesis examines the chromite concentrating process and the steel belt sintering process. It also reviews theories on the different methods for profile measuring and the equipment of currently used systems.

The experimental part develops the measuring system for pellet profiles. The method was based on a patent owned by Outokumpu. The developed system consisted of equipment and a connection for the automation system and software, including a graphical user interface, which was designed to control the whole system. The system was tested first in Espoo and later it was mounted beside the current profile measuring system at Tornio steelworks.

The average height profile was the largest magnitude the developed system was designed to output to the automation system. Additionally, the system enabled monitoring the real time trend of the horizontal profile and the mean value for both distance and time-based trends. Furthermore, integrated in the software is a 3D view of the profile. Traditional current and voltage messages allow communication between the profile measuring and automation systems. In addition to traditional I/O links, several OPC communication links for alarm limits and the set point were part of the build. The system was also equipped with self-diagnostics, which means that it raises an alarm in the case of an error.

Experiments done in Espoo and Tornio revealed that the developed system is fast and accurate. The measured vertical accuracy was 1-3 mm, depending of the measuring distance. The developed system was also 15 seconds faster than the current one. The user interface of the system was designed for flexibility and easy use. The developed system will replace the current system in Tornio, in 2005.

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