Modeling and Simulation of an Electrified Drop-tube Calciner
Keywords:drop tube reactor, electrification, CO2 capture, calcination, Python 3.8
AbstractAbout 65% of the carbon dioxide emissions from a modern cement kiln system are generated through calcination (decarbonation). The calcium carbonate in the limestone is the primary source of CO₂, and the rest comes from fuel combustion. This gives a calciner exit gas consisting of N2, O2, CO₂, and H₂O, the CO₂ constituting up to 30 % of the mixture. In the future, electric power will have to come from renewable energy. Electrification of the calciner, i.e., replacing fuel combustion with electrically generated heat, will eliminate the fuel combustion exhaust gases. The calciner exit gas will then be pure CO₂ and removes the need for a separate CO₂ capture plant. Such a process may require a new type of calcination reactor, different from the currently used reactors in most cement kiln systems. In the current work, an electrically heated drop-tube reactor (DTR) is used to calcine the meal. The DTR may replace the traditional entrainment calciner. Essential characteristics in developing a DTR include the particle size distribution (PSD), particle settling velocity, operational temperature of the tube wall, and velocity of the product gas. A PSD ranging from 0.2 to 180 µm, where most particles have a diameter < 30 µm, was investigated. Also, to assess the effect of clustering, an effective particle diameter of 500 µm was evaluated. Two different DTR designs were compared, 1) cocurrent flow of gas and particles, 2) counter-current flow of gas and particles. The dimensions of a calcination reactor were calculated using simulations in Python 3.8. The tube diameter was selected as the key parameter to see how the overall design of the reactor was influenced.
Robbie M. Andrew. Global CO2 emissions from cement production, 1928–2017, Earth Syst. Sci. Data, 10, 2213–2239, https://doi.org/10.5194/essd-11-1675-2019, 2018
Thomas P. Hills, Mark Sceats, Daniel Rennie, and Paul Fennella. LEILAC: Low cost CO2 capture for the cement and lime industries. Energy Procedia 114, pp. 6166–6170, 2017, doi: 10.1016/j.egypro.2017.03.1753
Phil Hodgson, Mark Sceats, Adam Vincent, Daniel Rennie, Paul Fennell, Thomas Hills. Direct Separation Calcination Technology for Carbon Capture: Demonstrating a Low Cost Solution for the Lime and Cement Industries in the LEILAC Project. 14th International Conference on Greenhouse Gas Control Technologies (GHGT-14), 21st–25th October, Melbourne, Australia, 2018
Frank P. Incropera, David P. Dewitt, Theodore L. Bergman, Adrienne S. Lavine. Principles of heat and mass transfer. John Wiley & Sons, Global edition, 2017.
Leilac, Low Emissions Intensity Lime & Cement, project web site, https://www.project-leilac.eu/, 2021
C. R. Milne, G. D. Silcox, D.W. Pershing, D.A. Kirchgessner. Calcination and sintering models for application to high-temperature, short-time sulfation of calcium-based sorbents. American Chemical Society, 29, 139-149, 1990. doi: https://doi.org/10.1021/ie00098a001
Norcem Heidelbergcement Group. Cement production and emissions. Retrieved (08.01.2021). Available online: https://www.norcem.no/en/Cement_and_CCS
Nastaran A. Samani, Chameera K. Jayarathna and Lars-André Tokheim. Fluidized bed calcination of cement raw meal: Laboratory experiments and CPFD simulations, Linköping Electronic Conference Proceedings (Proceedings of the 61st SIMS, September 22nd - 24th, virtual conference), pp. 399–406, 2020, https://doi.org/10.3384/ecp20176407
B. Stanmore, P. Gilot. Review – Calcination and carbonation of limestone during thermal cycling for CO2 sequestration, Fuel processing technology, 86: 1707 – 1743, 2005
Lars-André Tokheim, Anette Mathisen, A., Lars E. Øi, Chameera Jayarathna, Nils H. Eldrup and Tor Gautestad. Combined calcination and CO2 capture in cement clinker production by use of electrical energy, SINTEF proceedings, 4, pp 101-109, 2019
Ron Zevenhoven, Pia Kilpinen. Control of pollutants in flue gases and fuel gases, Helsinki University of Technology, 2001
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