Application of direct optical temperature measurement in the steelmaking process (DOT-Application)
Evaluation of the bath temperature distribution at the end of the main blowing phase of an LD-steelmaking converter revealed that about 20 % of the heats have a temperature deficit and must be re-blown. Another 30 % of the heats are overblown with too high a bath temperature. To overcome these disadvantages, a new online temperature measuring system was developed to enable direct determination of bath temperature during the oxygen blowing process. The measuring system uses an optical fibre which is continuously fed into the steel melt through a bottom gas stirring nozzle. The measurement device was installed at a 185 t converter and several test campaigns were performed. With regard to the number of measured heats, the availability of the measuring system itself was better than 98 %, but the availability of a free bottom nozzle was only about 40 % due to the formation of accretions at the nozzle tip. Since the accuracy of the measuring system is influenced by working conditions, it was addressed in laboratory trials and plant trials. A standard deviation of 13.4 K was determined in the plant trials, whereas it was identified as 9.5 K in the laboratory trials. The measuring system was also used for end-point control of the oxygen blowing process. This was performed by continuous temperature measurement in the final refining stage. Re-blowing due to temperature deficit or over-blowing with too high bath temperatures could be minimised. However, further research is needed to establish how the passage through the bottom nozzle can be kept clear.
Bibliographic Reference: EUR 23736 EN (2009), 45 pp. Euro: 15
Availability: Katalogue Number: KI-NA-23736-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.europa.eu
ISBN: ISBN: 978-92-79-11114-3
Record Number: 200910250 / Last updated on: 2009-04-10
Original language: en
Available languages: en