Minimising NOx emissions from reheating furnacesFunded under: ECSC-COAL-STEEL-RTD C
Primary NOx reduction with low NOx burners can be considered the best available technology (BAT) for steel reheating furnaces. In fact, the results of testing and modelling flameless low NOx burners for both high temperature air combustion (e.g. Techint TSX and VTS-NFK HRS burners) and oxy-fuel combustion (Air Liquide ALROLL-S burner) indicated that much lower NOx emissions are possible than with traditional flame burners. This gives the steel industry new opportunities to reduce the environmental impact of traditional furnaces, and the great potential for energy savings and reduced emissions with this technology are worth further investigation in the new RFCS CO2RED project. NOx emissions are strongly dependent on not only the type of furnace and equipment but also the operational conditions (for example, the excess air, and furnace and combustion air temperatures). Therefore the low NOx burner trials were made varying these major operational parameters. Reducing the excess air reduced the NOx in general for all the types of burners tested, which is useful up to the process limitations (CO emissions, etc.) and process control accuracy (as flow measurements). Oscillating combustion gave modest NOx reductions. Secondary NOx removal with high-temperature reduction (HTR) competes with SNCR as an alternative for the NOx removal method with ammonia after the combustion chamber, with both methods having their special advantages and disadvantages. The NOx predictions using Fluent were lower than experimental data for dilute and flameless combustion, but reasonably good predictions were possible for conventional flame burners (e.g. for the furnace at voestalpine). More complex reaction models using Chemkin were not successful in accurately predicting NOx. NOx could be predicted using an empirical neural network-based program called NANOx for NOx in reheating furnaces.
Bibliographic Reference: EUR 23202 EN (2008), 142 pp. Euro: 20
Availability: Katalogue Number: KI-NA-23202-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.europa.eu
ISBN: ISBN: 978-92-79-08182-8
Record Number: 201010006 / Last updated on: 2010-01-07
Original language: en
Available languages: en