IBC Conference, February 2002

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
• NiONiAl2O4
• La0.9Sr0.1Co0.5Fe0.5O3-2 (others)

4
Process Simulation
IC 3 stage intercooled compression, SAT
Saturator PH Preheater, HRHeat 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 lt dp lt 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
NiONiAl2O4 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
NiONiAl2O4 at elevated pressure
14
Experimental study II Reduction and Oxidation of
NiONiAl2O4 at elevated pressure
15
Summary
Experimental results are consistent and
promising High conversion rates for both
reduction and oxidation Excellent durability of
material (NiONiAl2O4) 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