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Chemical Looping Combustion

Chemical Looping Combustion. Øyvind Brandvoll Norwegian University of Science and Technology (NTNU). Trondheim 23. april 2003. Principle Process simulation Experimental work. INTRODUCTION. Characteristics: Fuel combustion is split into separate oxidation/reduction reactors

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Chemical Looping Combustion

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  1. Chemical Looping Combustion Øyvind Brandvoll Norwegian University of Science and Technology (NTNU) Trondheim 23. april 2003 • Principle • Process simulation • Experimental work

  2. INTRODUCTION • Characteristics: • Fuel combustion is split into separate oxidation/reduction • reactors • Fuel is not in direct contact with air • Oxygen transport by metal/metal oxide – binder complex • (MeO- Me)

  3. INTRODUCTION • Outline of CLC project: • Modeling of the system • Matlab • Pro II • Coupled Fortran-Pro II • Experimental study • Reduction with H2 and Methane/Steam • Oxidation with air • Carriers: • NiO:NiAl2O4 • La0.9Sr0.1Co0.5Fe0.5O3-2 (+others)

  4. Process Simulation IC: 3 stage intercooled compression, SAT: Saturator PH: Preheater, HR:Heat recovery cycle, HAT: Humid Air Turbine

  5. Process Simulation • Matlab Model • Mass & Heat balances • Standard equations for unit operations • Parameter Variation • TI: Ox Inlet • TR: Red Inlet • TU: Ox Outlet • TT: GT2 Inlet • TO: Red Outlet • PU: Reactor Pressure

  6. Process Simulation • Most important findings: • Oxidation inlet and outlet temperature has biggest • influence on efficiency • Highest efficiency: 53% with CO2 compression • Reduced exergy losses compared to conventional • combustion • Promising potential of CLC (power or heat generation)

  7. Experimental study I Reduction of Nickel oxide on nickel-spinel binder Shallow Fluidized bed reactor (I.D. 30 mm, Hb approx. 30 mm) Variables: Reaction Temperature (873-1123K) Particle Size (400 < dp < 2600 m) Particle Composition (%NiO = 60, 80, 90)

  8. Experimental study I Reduction of Nickel oxide on nickel-spinel binder Monitoring degree of oxidation of material :

  9. Experimental study I Reduction of Nickel oxide on nickel-spinel binder Decreasing temperature

  10. Experimental study I Reduction of Nickel oxide on nickel-spinel binder Arrhenius plot Pore diffusion Particle external diffusion

  11. Experimental study I Reduction of Nickel oxide on nickel-spinel binder Conclusions Rate limited by mass transfer mechanisms, not chemical kinetics Constant rate with nearly complete conversion for small particles and high temperatures No chemical or mechanical degradation observed after 40 cycles

  12. Experimental study II Reduction and Oxidation of NiO:NiAl2O4 at elevated pressure Performed in cooperation with SINTEF Kjemi, Oslo • Flue gas analysed with MS • Data for reduction AND oxidation: • Variation in reactor pressure and feed concentration • (data for experiments at 10 bara still being processed)

  13. Experimental study II Reduction and Oxidation of NiO:NiAl2O4 at elevated pressure

  14. Experimental study II Reduction and Oxidation of NiO:NiAl2O4 at elevated pressure

  15. Summary Experimental results are consistent and promising High conversion rates for both reduction and oxidation Excellent durability of material (NiO:NiAl2O4) Preliminary results with methane/steam indicate that reforming of fuel to H2/CO2/CO is important!

  16. The path ahead • Reduction tests with methane/steam • Screening of other potential oxygen carriers • Application of recent experimental data in new • simulations • In a 5 year perspective: • Continous, lab-scale, methane/air fueled dual reactor • CLC ”pilot plant” with online flue gas analysis

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