Radiative transfer models for rotary kilns - from fossil fuels to hydrogen gas and thermal plasmas
Licentiatavhandling, 2025
This thesis investigates the effects on the heat transfer within rotating furnaces that occur when substituting fossil-based fuels for alternatives, such as hydrogen gas and electrically aided heating using thermal plasmas. The focus is on radiative heat transfer assessed in rotary kiln processes (high-temperature processes) that are used for iron ore and cement production.
Paper I present a heat transfer modeling study employing adiabatic flame temperature conditions, showing that the fuel shift from coal to hydrogen gas in rotary kilns for iron ore production significantly increases the local heat transfer rate to the inner surface of the kiln wall. Specifically, the heat transfer rate is affected near the burner region, achieving high levels for the hydrogen flame. Further investigations of the local effects of fuel shifting in rotary kilns require precision in terms of the heat transfer calculations, motivating the development of an updated gas radiation model, as presented in Paper II, and the application of such gas radiation models with computational fluid dynamics codes, as presented in Paper III.
By combining computational fluid dynamics codes with the updated gas radiation model, the present work concludes that, although using hydrogen gas as a fuel effectively reduces carbon dioxide emissions and particle formation, heat transfer during hydrogen firing is less efficient than during coal firing. Consequently, most of the heat transferred from fuel heat release exits with the flue gases during hydrogen combustion due to increased flame temperatures. This indicates a need for either coal-hydrogen co-firing conditions, as the presence of particles may enhance effectively the heat transfer rate within the kiln or alternative kiln designs.
Radiative heat transfer
hydrogen
rotary kilns
thermal plasma
Författare
Elias Ehlmé
Chalmers, Rymd-, geo- och miljövetenskap, Energiteknik
Heat Transfer Conditions in Hydrogen-Fired Rotary Kilns for Iron Ore Processing
Industrial & Engineering Chemistry Research,;Vol. 62(2023)p. 15098-15108
Artikel i vetenskaplig tidskrift
Updated Weighted-Sum-of-Gray-Gases Model Parameters for a Wide Range of Water and Carbon Dioxide Concentrations and Temperatures up to 5000 K
ACS Omega,;Vol. 10(2025)p. 2978-2985
Artikel i vetenskaplig tidskrift
Ehlmé E. Gunnarsson A. Normann F. Andersson K. An Assessment of Weighted-Sum-of-Grey-Gases Models for Computational Fluid Dynamics Modelling of Hydrogen Flames and Thermal Plasmas in Kilns
Utveckling av vätgasförstärkt värmningsteknik för roterugn-elektrifiering av svensk järnmalmsförädling
Energimyndigheten (P2022-00196), 2022-07-01 -- 2025-06-30.
LKAB (Ordernr 8088686), 2022-07-01 -- 2025-06-30.
Drivkrafter
Hållbar utveckling
Styrkeområden
Energi
Fundament
Grundläggande vetenskaper
Ämneskategorier (SSIF 2025)
Energiteknik
Infrastruktur
Chalmers e-Commons (inkl. C3SE, 2020-)
Utgivare
Chalmers
HA2, Hörsalsvägen 4. Password to Zoom: 123456
Opponent: Prof. Dr.-Ing. Viktor Scherer, Faculty of Mechanical Engineering, Ruhr Universität Bochum