dynamic simulation of oxy combustion in a pilot scale cfb
TRANSCRIPT
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
Dynamic Simulation of Oxy Combustion in a Pilot Scale CFB Boiler
Hultgren M (Oulu), Lohiniva L (Oulu), Kovács J (FW), Ritvanen J (LUT) & Tourunen A (VTT)
Matias Hultgren
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
Aims of the Simulation Study
• 1-D CFB hotloop model: dynamic & steady-state, Matlab/Simulink
• Main process dynamics of oxy-CFB • Model validation with experimental data,
oxy combustion• Preliminary simulations for pilot tests • Modelling purpose:→ Further simulations to understand the
process, air vs. oxy→Combustion control studies with
traditional & advanced control solutionsModified from: Kuivalainen et al. (2009, 11)
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
The Hotloop Model
• 1-D elements with mass & energy balances solved against time• Gas phase heterogenous reactions: C, H & S• Combined energy equation for temperatures• Phases incompressible and have same T, solids Cp constant• Furnace cooling: Tref, Tfur & Tcyc
• Hydrodynamics, combustion & heat transfer: semi-empirical correlations, empirical vertical density profile
• Turbulent conditions → energy dispersion
HOTLOOP
Fuel
Prim./Sec. oxidant
Solid circulation/ash
Cooling parameters
Flue gas flow
Evaporator heat flux
Separator heat flux
Furnace profiles
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
ACFB furnace block, separator & return leg of the hotloop model
5
Furnace profiles
4
heat flux sep
3
heat flux evap wall
2
Flue gas1
time
fluidvelocities
fluid velocities
rleg
fluegas1furout
fluegas
circulation
Separator
U Y
Selector
slmemoJR
S-Function2
Mux
Mux3
fgprop
Goto
Clock
ACFB
10f_kC
9solid control
8T sep wall
7T furn
6T sloped
5T circulation
4qm circulation
3Secondary gas
2Primary gas
1Fuel
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
• File structure:– Dynamic (.mdl) model:
• hotloop module (furnace, gas-solid separator, solids return system) • external gas mixing module (2-stage mixing of input gases)
– Configuration and statefile (.sim) files– m-files: process inputs, simulation & output handling
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
Model Validation
• Measured RFG, pure O2 & air as direct inputs• Anthracite & petcoke mass flows from silo weights• One combined fuel flow input, properties calculated• Flue gas O2 good indicator of combustion, sensitivity• Silo measurement inaccuracies & drifting fuel composition→ Fuel flow correction:• Matching FG O2 to measurements• Corrected fuel input for simulations• Model validation with temperatures, CO2, H2O, etc.
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
Outcomes of the Study
• Model successfully validated for oxy-CFB• Focus on process dynamics• Simulations confirmed measurement conclusions
– Step tests– Ramp tests– Switch tests
• Further development:– Improved modelling accuracy– Multifuel approach to counter changes in fuel composition– Air leakage → effect on flue gas concentrations– Temperature levels → furnace cooling– Oxy combustion control testing → importance
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
Thank You for Your attention!
Compostilla power station, Spain
CIUDEN 30 MWth oxy combustion and CCS test facility
Modified from: http://www.vtt.fi/files/sites/flexiburncfb/flexiburncfb_poster.pdf
SYSTEMS ENGINEERING LABORATORYMATIAS HULTGREN, 27.01.2012
Picture References
• Hultgren M (2011) Comparative Study of Oxy and Air Combustion on a Pilot CFB Boiler. Oulu, University of Oulu, Department of Process and Environmental Engineering, Systems Engineering Laboratory. 145 s.
• Kuivalainen R, Pikkarainen T, Leino T, Tourunen A (2009) Development of CFB Technology to Provide Flexible Air/Oxy Operation for a Power Plant with CCS. At: The 34th International Technical Conference on Coal Utilization & Fuel Systems, 31.05. – 04.06.2009, Clearwater, Florida, USA [referenced 17.01.2012]. Foster Wheeler Energia Oy, VTT Technical Research Center of Finland. 13 s.
• VTT (date unknown) Development of High Efficiency CFB Technology to Provide Flexible Air/Oxy Operation for Power Plant with CCS [poster presentation]. FLEXI BURN CFB – EU FP7 I 2009-2012 [referenced 17.01.2012]. VTT Technical Research Center of Finland. Availability: http://www.vtt.fi/files/sites/flexiburncfb/flexiburncfb_poster.pdf