Advanced Multiphase Simulation of Rotary Kilns:
Coupling of ANSYS Fluent and a Third Party Solver
Eero Immonen
Process Flow Ltd Oy
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
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
Example: Rotary kilns in cement making
Schematic by Prosperity Minerals Holding LTD
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-gas-
emitting 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!
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. CO2, H2O, ...)
from the bed feed to the gaseous phase
Introducing KilnSimu by VTT
KilnSimu is a generic 1D multiphase simulator for rotary kilns
State of the art resolution of bed chemistry using ChemApp
Issue: Need a priori information on the combustion
conditions (e.g. flame position) in order to obtain a
realistic overall solution
Gas in
Bed out
Celli Cell1 CellN
Bed in eq.
dust+
volatiles
Gas out
Bed in
Mass transfer of gas species between bed and
gas. Convection and diffusion between gas and
bed.
Mass transfer of condensed species between
bed and gas. Dusting of solid particles and
formation of liquid phases.
convection+
diffusion
dust+
volatiles
convection+
diffusion
dust+
volatiles
convection+
diffusion
condensed condensed condensed
Bed in eq. Bed in eq.
Gas in eq. Gas in eq. Gas in eq.
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
Schematic flow chart of the coupled solution
Fluent KilnSimu
Simulation
parameters
Parameter
files *.dat
Set-up Fluent
and KilnSimu
or read
parameters
Solve KilnSimu
domains
Export
interface
fluxes
Read
interface
fluxes
Solve gas
domain
Export
interface
heat fluxes
Post-
processing
Post-
processing
Global solution loop
Geometry
and mesh
Read
interface
heat fluxesFlu
en
t so
lutio
n lo
op
Kiln
Sim
u s
olu
tio
n lo
op
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: CO2 sources on bed feed
surface
A. Drum wall (lining): Temperature boundary condition
Drum shell
Drum lining
Gas volume
Feed volume
A. C. B.
Ilustration of the coupled solution
Resulting gas temperature profile
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!
THANK YOU!
For more information go to:
http://www.kilnsimu-fks.com/
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