Advanced Multiphase Simulation of Rotary Kilns: Coupling of ANSYS Fluent and a Third Party Solver. Eero Immonen Process Flow Ltd Oy

Transcription

1 Advanced Multiphase Simulation of Rotary Kilns: Coupling of ANSYS Fluent and a Third Party Solver Eero Immonen Process Flow Ltd Oy

2 Contents Introduction to rotary kilns Why simulate? Optimization (energy consumption, emissions) Overview of the simulation challenges Solution: Coupling of ANSYS Fluent and KilnSimu by VTT Samples and illustrations Benefits of the coupled solution

3 Rotary kilns in industrial processes Rotary kilns are huge (!) pyroprocessing devices used to raise materials to a high temperature Primary uses include: Manufacturing of pigment, cement, oxides,... Lime calciner in the recovery cycle of chemicals (pulping) Roasting of sulfide ores prior to metal extraction Slow rotation along primary axis ~ 1 rpm

4 Example: Rotary kilns in cement making Schematic by Prosperity Minerals Holding LTD

5 Characteristics of rotary kilns A critical part of the manufacturing process The kiln capacity defines the overall plant capacity The main energy-consuming and greenhouse-gasemitting stage of production Significant need for understanding the process and its parameters (e.g. heat transfer to the bed feed along kiln) Significant optimization potential (e.g. burner section) Extreme operating conditions High temperatures Vibration Corrosion Challenging environment for measurements simulate!

6 Simulation challenges True multiphysical environment Solid phase phenomena (bed feed) Particulate motion, erosion, heat transfer, chemical reactions (calcination),... Gaseous phase phenomena Combustion, turbulent flow, multitude of fuels Coupling of the solid and gaseous phase Heat transfer from gas to the walls and bed feed Transfer of reaction products (e.g. CO 2, H 2 O,...) from the bed feed to the gaseous phase

7 Introducing KilnSimu by VTT KilnSimu is a generic 1D multiphase simulator for rotary kilns State of the art resolution of bed chemistry using ChemApp Cell 1 Cell i Cell N Mass transfer of gas species between bed and gas. Convection and diffusion between gas and bed. Gas out Gas in eq. Gas in eq. Gas in eq. Gas in convection+ diffusion convection+ diffusion convection+ diffusion Mass transfer of condensed species between bed and gas. Dusting of solid particles and formation of liquid phases. Bed in dust+ volatiles dust+ volatiles dust+ volatiles condensed condensed condensed Bed out Bed in eq. Bed in eq. Bed in eq. Issue: Need a priori information on the combustion conditions (e.g. flame position) in order to obtain a realistic overall solution

8 Solution: Coupling of ANSYS Fluent and KilnSimu Gaseous and solid phase simulation in 1D in KilnSimu General-purpose solver for any rotary kiln application Gaseous phase simulation in 3D in ANSYS Fluent High-performance multi-phase CFD modeling environment hosting a leading selection of combustion sub-models Chemical reaction modeling, especially in turbulent conditions, has been a hallmark of Fluent since its inception Coupling of Fluent and KilnSimu: KS Fluent KS... Unit conversions and front-end code for rapid simulation setup 1D 3D 1D geometry interfacing routines with interpolation Heat and mass transfer treatment on solid-gas interfaces - Automated setup of b.c s and c.z.c s in Fluent Built-in postprocessing features

9 Schematic flow chart of the coupled solution Geometry and mesh Fluent KilnSimu Set-up Fluent and KilnSimu or read parameters Parameter files *.dat Global solution loop Simulation parameters Fluent solution loop Read interface fluxes Solve gas domain Export interface fluxes Export interface heat fluxes Solve KilnSimu domains Read interface heat fluxes KilnSimu solution loop Postprocessing Postprocessing

10 Illustration of the coupling: KilnSimu Fluent Initial data calculated by KilnSimu are transferred to Fluent A. Bed feed surface: Temperature boundary condition B. Gas volume: CO 2 sources on bed feed surface A. Drum wall (lining): Temperature boundary condition Drum shell Drum lining Gas volume Feed volume A. B. C.

11 Ilustration of the coupled solution Resulting gas temperature profile

12 Benefits of the coupled simulation Fewer a priori assumptions about combustion needed in KilnSimu to obtain realistic results Enhanced accuracy in estimating the gas-volume phenomena compared to the 1D treatment in KilnSimu Facilitates a detailed analysis, and optimization, of the burner area - this is not possible in a 1D solution More accurate description of radiation heat transfer Possibility of studying a large variety of chemical states in the feed, and, simultaneously, analyzing the associated gas volume phenomena The coupled simulation helps reduce energy consumption and control emissions in rotary kilns!

13 THANK YOU! For more information go to: