Session: 3.2 - Computational Turbulent Combustion

Paper Number: 157261

157261 - CFD Modeling of Multiphase Turbulent Oxy-Petroleum Coke Combustion to Enhance CO2 Capture in Full-Scale Cement Kiln Precalciner 

Abstract: 

This paper presents a CFD study using multiphase hybrid 3-D Computational Fluid Dynamics-Discrete phase model/Advanced DPM and Kinetic theory of granular flow (CFD-DPM/DDPM & KTGF) methods for the mathematical modeling of the oxy-combustion, heat exchange and limestone calcination within a precalciner vessel unit of a full-scale cement kiln. The CO₂ capture and storage/ sequestration (CCS) techniques will be used shortly to retrofit commercial cement plants. The oxy-fuel combustion technology is designed to utilize pure O₂ mixed with wet recycle flue gas (mainly CO₂) to burn the fuel producing a highly concentrated CO₂ stream (higher than 60 vol-%). CO₂ stream is further purified by condensing the H₂O vapor. The “partial” atmospheric oxy-fuel combustion capture is an approach where only the precalciner unit is operated under oxy-fuel combustion with the rotary kiln unit which is operated on conventional atmospheric air-fuel combustion. The RFG is used to control the temperature field within the PC vessel unit. An unchanged weight of “thermal ballast” diluent gas amount (CO₂ a denser gas, instead N₂ gas), to ensure that there is enough gas, both to transfer heat and to enhance particle’s lifting inside the PC vessel unit of 5-stage SPH, respectively. To reach a similar adiabatic temperature, as for the conventional air-fuel combustion, O₂ proportion of supplied oxidizer through separate tangential duct and the auxiliary burners are typically around 30 vol-%, higher than that the conventional air-fuel combustion. The numerical simulations of a commercial-scale precalciner unit were fully validated by the present authors against the industrial measurements carried out under conventional air-petcoke combustion conditions. We used the CFD software Ansys Fluent 2022 release R2 to run a number of four oxy-fuel environment scenarios, with the O₂ concentration in oxidizer composition ranging from 21 vol-% to 38 vol-%. The various input parameters of constructed 3-D CFD model were: oxygen concentrations, recycle flue gas ratios and in-air leakages wet or dry. Some of the recent findings on specific CFD submodels were used (e.g., heat radiation and mass transfer, char oxidation and gasification submodels properly adapted for CO₂-rich environment, etc.). The effects of the environment changing on thermodynamics, kinetics and equilibrium chemistry for cement clinker formation are major process issues. CFD predicted results are provided for the OxF28 scenario only, in terms of multiphysics phenomena, e.g., thermal-flow aerodynamics, radiative, convective and conductive heat transfer, volatile combustion, char-burnout, residence time of particles. The purpose of this work is to report on the comparison of the numerical simulation results for a CFD engineering problem concerning a commercial-scale precalciner unit theoretically tested under oxy-fuel combustion mode, against the available literature experimental results performed, for the time being, only on the lab/pilot-scale R&D facilities. Keywords: cement kiln precalciner unit; oxy-fuel combustion; CO₂ capture and storage; CFD-DPM/DDPM & KTGF methods; solid-gas phase reactions; calcination in CO₂-rich atmosphere.

Presenting Author: Eugen Dan Cristea None

Presenting Author Biography: Eugen-Dan Cristea, Ph.D., received his doctorate degree in Thermal Sciences (Thermodynamics
/Combustion Science) from Politehnica University of Timisoara, Romania, and awarded with his M.Sc. degree in Thermal Power Engineering from Politehnica University of Bucharest, Romania. He carried out his postdoctoral fellowship, as visiting adjunct assistant professor, at Montana State University at Bozeman, MT, USA to perform CFD numerical simulation work for MHD combustor fired on natural gas. He has served as Head of the MHD (magneto hydro-dynamics) research laboratory of Scientific Research Division (former Power Institute of Romania Academy of Sciences) at the Institute of Scientific Research and Technological Engineering for Power Equipment in Bucharest, Romania.
Since 1987 Dr. Cristea moved to industry, starting to work in the industrial combustion field for cement and lime industry. In 1996 he was appointed Technical Director at Cimprogetti S.p.A., a worldwide recognized engineering firm for design, construction and commissioning of lime vertical kiln plants, located in Dalmine (BG), Italy. In 2007 he re-joined, as Manager of Combustion Department, the Italcementi Group, an international cement manufacturing player, located in Bergamo, Italy.
Since 2013, after his retirement, he performed part-time CFD consultancy business for cement and/or lime industry.
He is member of the American Society of Mechanical Engineers and of the International Flame Research Foundation at Livorno (Italy) and he served as member of the Italian Flame Research Committee.
Dr. Cristea has co-authored two combustion related books, one combustion book chapter, over 26 journal articles, over 22 international conference papers. He holds 5 patents for novel combustion equipment. He has delivered seminar lectures at International Flame Research Foundation.