Lindell D.,Swerea Kimab Ab |
Ekman T.,AGA AB |
Steel Research International | Year: 2015
Pilot plant and annealing experiments have been conducted to study the effect of the higher water content in oxyfuel annealing on oxidation and pickling of cold rolled stainless steel. The experiments were conducted on the austenitic grade AISI 304 in a propane-fired furnace using air and pure oxygen as oxidizers. The experiments were conducted at 1050-1200 °C for typically less than 60 s, in order to simulate industrial annealing of thin strip. Supplementary laboratory annealing trials were made to study the evolution of the microstructure during fast heating rates and short hold times. Increasing the water content from 15 to 50 mol% did not alter the oxidation kinetics or the chemistry of the oxide. Since the oxidation is not altered significantly, the pickling performance of the material remains unchanged. The presence of spalled areas increased the pickling efficiency significantly but this was only seen for material annealed at higher temperature compared to industrial practice. Oxyfuel combustion allows higher heat input and therefore faster heating. The 304 grade recrystallizes readily even at moderate cold rolling reductions so the total annealing time can be reduced substantially if the heating rate can be increased. The present work suggests that this can be done without any downstream effects. Pilot plant annealing experiments have been conducted to study the effect of the higher water content, caused by altering the oxidizer in combustion furnaces, on oxidation and pickling of cold rolled stainless steel. Characterization of oxide, microstructure, mechanical properties, and pickling response suggests that the increasing the water content from 15 to 50 mol% does not result in any negative downstream effects. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source
Li J.,KTH Royal Institute of Technology |
Yang W.,KTH Royal Institute of Technology |
Blasiak W.,KTH Royal Institute of Technology |
Fuel | Year: 2012
To meet the urgent environmental targets, substituting coal with biomass has been considered to be an effective and promising method over the last decades. In this paper, a new concept of volumetric combustion is proposed and further developed to achieve 100% fuel switching to biomass in large scale coal-fired boilers. Volumetric combustion not only changes the in-furnace flow but also affects the combustion reactions by the intensive mixing and internal recirculation of the flue gases. Firstly, the volumetric combustion properties of the wood pellets were investigated experimentally. An Aspen model was then used to thermodynamically describe and study the volumetric combustion with three different types of fuel, and the emission properties of CO 2 and NOx were compared. Finally, two applications of volumetric combustion were discussed. It is concluded that the wood pellets ignited and combusted much faster than the coal pellets and had a larger combustion volume when combusted under lower oxygen concentration conditions, and the ignition time was almost independent of the oxygen concentration when the oxidizer was preheated to 1000 °C. In addition, the NOx emissions decreased as the recirculation ratio of the flue gas increased, and as the percentage of biomass used in co-firing increased, the amount of flue gas that needs to be recycled for reduction of NOx decreased. Thus, the volumetric combustion is beneficial as it reduces the operation cost of NOx reduction. The volumetric combustion would be an attractive technology for co-firing a large proportion of biomass in coal-fired boilers with high boiler efficiency and effective emissions reduction. © 2012 Elsevier Ltd. All rights reserved. Source
Morfeldt J.,KTH Royal Institute of Technology |
Silveira S.,KTH Royal Institute of Technology |
Hirsch T.,SSAB |
Lindqvist S.,Sandvik AB |
And 3 more authors.
Energy Efficiency | Year: 2015
European steel producers need to increase energy efficiency and reduce CO2 emissions to meet requirements set by European policies. Robust indicators are needed to follow up these efforts. This bottom-up analysis of traditional energy and climate indicators is based on plant-level data from three Swedish steel producers with different product portfolios and production processes. It concludes that indicators based on both physical and economic production are interlinked with aspects both within and outside the company gates. Results estimated with partial least squares regression confirm that steel production has complex relationships with markets, societal context, and operational character of the industry. The study concludes that (i) physical indicators (based on crude steel production) may be useful at the process level, but not at the industry-wide level, (ii) the value added is not a reliable alternative since it cannot be properly estimated for companies belonging to larger international groups, and (iii) structural shifts may influence the results significantly and veil improvements made at the process level. Finally, harmonised system boundary definitions are vital for making indicators comparable between companies. The use of traditional indicators, as defined today, may lead to uninformed decisions at the company as well as policy levels. © 2014, Springer Science+Business Media Dordrecht. Source
Jernkontoret | Date: 2011-09-07
Method for producing nano sized ferrite particles from a metallurgical slag, the method including the steps of: a) providing a ladle with a molten slag including CaO, SiO2, FeO, and at least one of MnO, Cr2O3, V2O3. b) oxidizing the slag at a temperature in the interval of 1573K-1773K (1300-1500 C.) for 10-90 minutes, c) removing at least a portion of the slag from the ladle d) cooling the removed slag portion to a temperature below 373K (100 C.), e) extracting nano sized manganese ferrite and/or chromium ferrite and/or vanadium ferrite particles from the cooled portion.
Jernkontoret | Date: 2013-08-14
The invention concerns a process for recovering at least one rare earth metal (REM) from the group of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. A chloride salt melt is provided and aluminium chloride is used to chlorinate a REMcontaining resource. The REM can be recovered by electrolysis, vaporisation or hydrometallurgical methods.