investigation of the calcination of caco by the...

Investigation of the calcination of CaCO3 by the simultaneous reduction of CuO with a fuel gas in a fixed-bed reactor

J.M. Alarcón, J. R. Fernández , J. C. Abanades

J.M. Alarcón*, J.R. Fernández, J.C. [email protected]

Investigation of the calcination of CaCO3 by the simultaneous reduction of CuO with a

fuel gas in a fixed-bed reactor

6th IEAGHG High Temperature Solid Looping Cycles Network Meeting, September 1-2, 2015, Milan

INSTITUTO NACIONAL DEL CARBÓN (INCAR-CSIC)



Introduction 1

2

3

4

5

6

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests

Outline

Experimental set up

Model description

Heat transfer tests

Reduction tests

Reduction/Calcination

tests

Conclusions7

Conclusions

Reduction/calcination tests



The Ca/Cu Looping Process(Abanades & Murillo, CSIC, EP09382169.2, 16th Sep 2009)

(Abanades et al., Env. Sci. Tech., 44, 6901-6904, 2010)

Endothermic/exothermic reactionscoupled in the same bed matrix

efficiency

Equipment cost

Based on the “unmixed reformingconcept” (Kumar et al., 2000)

Chemical Looping+

Chemical Looping Combustion

CaO for CO2 capture in thereformer (higher H2 yield)

Steam reforming + CaO carbonation

Cu oxidation

CuO reduction+ CaCO3 calcination

CO2 rich product gas suitablefor transport and storage

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



FEED GASES

PREHEATING

GASES

FIXED-BED

REACTOR

IR & TC

ANALYZERS

Experimental set up

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



Material: Inconel

Internal diameter: 0.038 m

External diameter: 0.042 m

Height: 1 m

Solids mass: around 1 kg

Multipoint type K thermocouple (15

points)

Insulating material: quartz wool

FIXED-BED REACTOR

Experimental set up

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



Pseudo-homogeneous model

Mass and thermal dispersion in axial direction

Ideal gas behaviour

Negligible intraparticle mass and temperature gradients

Constant bed void fraction

Uniform particle size

Perfect mixing of the solids

Negligible carbon deposition

ASSUMPTIONS

Model description

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



Mass balance

Energy balance

/ ;

Kinetics of CuO reduction

Kinetics of CaCO3 calcination

/

Axial pressure distribution

(García Labiano et al., 2004)

(Martínez et al., 2012)

Model description

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



PARAMETERS VALUES

Feed gas temperature, Tgin 475 ºC

Initial solids temperature, Ts0 26 ºC

Pressure, P 1 atm

Inlet flow velocity 40 LN/min

Particle size, dp 0.003 m

Reactor length, L 0,92 m

Reactor diameter, D 0,038 m

Bed porosity, ε 0.5

Bed density, ρs 1920 kg/m3

Operating conditions

U= 5 W/m2K

HEATING OF THE PACKED BED

Heat transfer tests

Axial temperature profiles

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



PARAMETERS VALUES



Pressure, P 1 atm








U= 5 W/m2K

HEATING OF THE PACKED BED

Heat transfer tests

Outlet gas temperatures

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions




PARAMETERS VALUES



Pressure, P 1 atm






CuO density, ρCuO 380 kg/m3


Reduction tests

CO2 H2 as fuel gas

CO2

CuO-based particles: 60% active

Ca-based particles: 12% active

CaO as inert material underthese conditions

CO2 20% of CuO

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



Reduction tests

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions

Breakthrough between 6 and 9 minutes

Validation of the model

R

High reactivity of H2 with CuO

HR




PARAMETERS VALUES



Pressure, P 1 atm






CuO density, ρCuO 380 kg/m3

CaCO3 density, ρCuO 249 kg/m3


CO2H2 as fuel gas

CO2

CuO-based particles: 60% active

Ca-based particles: 12% active

Cu/Ca molar ratio=1,8

CO2

Temperature of solids bedvarying from 415 ºC (bottom) to 720 ºC (top)

Effect of starting temperature on reduction/calcinationoperation

Reduction/calcination tests

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



RHC

C

High reactivity of H2 with CuO even at low temperatures (400ºC)

Calcination of CaCO3 is negligible below 800 ºC

At 870ºC (t>5min) calcination is highly favoured

flow gas rate by calcination: heat exchange front advances faster

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



t=2 mint=5 min t=7 min

CaCO3 conversiont<2 min, Rapid and total reduction of the CuO

t<5 min, T=870ºC Reduction and calcination fronts advance together

Leaving behind the second part of the reactor totally converted.

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



Conclusions

CO2

Experimentally demonstrated that the reduction of CuO with a fuelgas can supply the energy required to carry out the calcination ofCaCO3 in a same fixed-bed reactor.

The dynamic model gives a good description under the operatingconditions considered.

CO2

CO2

A balanced Cu/Ca molar ratio in the bed makes both reduction andcalcination fronts advance together with moderate maximumtemperatures (870 ºC), leaving behind solids totally converted.

CO2

CO2

Temperatures lower than 800 ºC allow a rapid reduction of CuO withH2, but not the calcination and part of the bed can be left uncalcined.

Future work: study of the key design parameters: Cu/Ca molar ratio,temperature and composition of the fuel gas, alternative fuel gases(CH4, CO) and other materials for the Ca/Cu looping process, and thestudy of the oxidation step with different N2 dilutions.

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions



Investigation of the calcination of CaCO3 by the simultaneous reduction of CuO with a

fuel gas in a fixed-bed reactor

6th IEAGHG High Temperature Solid Looping Cycles Network Meeting, september 1-2, 2015, Milan

INSTITUTO NACIONAL DEL CARBÓN (INCAR-CSIC)

Thank you for your attention!



Axial mass dispersion coefficient

Effective axial heat dispersion

Gas-to-particle heat transfer coefficient

(Edwards and Richardson, 1968)

(Vortmeyer and Berninger, 1982)

(Krupiczka, 1967)

(Gunn and Misbah, 1993)

(Gunn, 1987)

Model description

Introduction

Experimental set up

Model description

Heat transfer tests

Reduction tests


tests

Conclusions

investigation of the calcination of caco by the...

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