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CO 2 Capture from Gasification Syngas via Cyclic Carbonation / Calcination. Robin Hughes CANMET NRCan. Robert Symonds, University of Ottawa Supervisors Dr. A. Macchi Dr. E. J. Anthony. Overview. Introduction Hydrogen production in Canadian context Objectives Experimental Method

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co 2 capture from gasification syngas via cyclic carbonation calcination

CO2 Capture from Gasification Syngas via Cyclic Carbonation / Calcination

Robin Hughes

CANMET

NRCan

Robert Symonds, University of Ottawa

Supervisors

Dr. A. Macchi

Dr. E. J. Anthony

overview
Overview

Introduction

    • Hydrogen production in Canadian context

Objectives

Experimental Method

Results

  • Kinetic parameters
  • Sorbent decay
  • Morphology
  • Observations

Operational CANMET pilot facilities for CO2 looping studies

Summer 2008 Testing

introduction gasification
Introduction - Gasification

In Canada, very large quantities of H2 will be produced via gasification for heavy and ultra heavy oil upgrading, power production, and possibly transportation

  • The production of syngas (mainly CO and H2) from a number of carbonaceous fuel sources including coal, petroleum coke, oil, asphaltenes, and biomass occurs via:

3C + O2 + H2O -> 3CO + H2

  • The syngas can be shifted to hydrogen via the water-gas shift reaction in the presence of steam

CO + H2O -> CO2 + H2

  • The production of hydrogen via gasification results in high CO2 emissions unless the CO2 can be sequestered
h 2 production for oil sands using gasification
H2 Production for Oil Sands using Gasification

Oil Sands – Need low cost hydrogen

Production and upgrading facilities are expected to grow by a factor of 5 over the next 25 years.

Aggregate Production Forecast:

2003 – 1.1 million b/d 2012 – 2.0 million b/d 2030 – 5.0 million b/d

  • Natural gas price is volatile and supply will diminish;
  • Will need alternative fuels (coal, petroleum coke and refinery residues) to meet the demand; however,
  • Higher carbon fuels will increase CO2 emissions
h 2 production comparison
H2 Production Comparison
  • CO2 emissions are increased when producing H2 from asphaltenes and pet coke when compared to natural gas
  • If 90% CO2 capture with gasification assumed then emissions are less than SMR with natural gas
  • Gasification for hydrogen with CO2 capture and compression (ex. 150 bar) is less energy intensive and more cost effective

W/O CO2 Capture

W/ 90% CO2 Capture

Source: White 2007, Air Products

canadian gasification with ccs
Canadian Gasification with CCS

EPCOR - 90% CO2 capture

  • Genesee 4 – 500 MW coal IGCC for electrical power production
  • Front end engineering design underway
  • FEED funding industrial/provincial/federal
  • 8000 TPD coal

Sherritt – ~4.5 Mt/yr CO2

  • Dodds-Roundhill – 270 MSCFD hydrogen production via coal gasification
  • Hydrogen to be used for oil sands upgrading

Opti-Nexen – Long Lake project

  • Oil sands operator producing very high quality synthetic crude oil
  • Gasifying asphaltenes for H2, steam, and power
  • Phase I includes 4 Shell gasifiers
introduction co 2 sorbents
Introduction - CO2 Sorbents

Investigating methods for syngas CO2 separation that can be performed at high temperature and pressure

  • Metal oxides have high equilibrium capacities.
  • Can generate a nearly pure stream of CO2 (>85 %) needed for sequestration
objectives
Objectives
  • Determine the effect of ‘slagging gasifier’ syngas on carbonation reaction kinetics for naturally occurring calcium oxide based sorbents.
  • Determine reaction kinetics for the development of a single phase, plug flow, moving bed carbonator reactor model.
  • Perform sensitivity / parametric analysis of carbonator reactor model.
experimental conditions
Experimental Conditions

Naturally occurring calcium oxide based sorbents

  • Havelock Limestone
  • Newfoundland Dolomite

Particle size range

  • 250 – 425 micron
experimental conditions12
Experimental Conditions

Feed Gas – Carbonation

  • GE gasifier with Illinois bituminous coal as a feed (Simbeck et al., 1993)
  • CH4, H2S, NH3, and HCN have been omitted from the syngas feed stream
experimental conditions13
Experimental Conditions

Temperature – Carbonation

  • 580, 620, 660, 700oC

Feed Gas – Calcination

  • N2
  • CO2 and N2 (similar to Abanades et al., 2003)

Temperature - Calcination

  • 850 and 915oC

Atmospheric pressure, 10 cycles

rate of reaction
Rate of Reaction

Reaction rate given by

maximum slope for grain

model

effect of carbonation feed gas
Effect of Carbonation Feed Gas
  • Presence of CO/H2 have increased the initial rate of carbonation by 70%
  • Increased local CO2 concentration at CaO surface?
  • Believe CaO or an impurity may be catalyzing the water-gas shift reaction
  • Calculated activation energies are 60.3 and 29.7 kJ/mol with and without the presence of CO and H2 during carbonation
  • Sun et al. (2008) determined activation energy was 29 ± 4 kJ/mol without CO/H2
sorbent decay
Sorbent Decay
  • Presence of CO and H2 during the carbonation of Havelock particles have little impact on the CaO conversion over 10 cycles
  • Expected since particle sintering should be similar based on identical calcination conditions, but sorbent morphology indicates physical differences
presence of steam
Presence of Steam
  • The presence of steam increases the carbonation conversion by approximately 30% at the end of the 10th cycle
  • Several authors (Lin et al., 2005 and Gupta et al., 2002) observed a significant increase in CaO conversion via the intermediate formation of Ca(OH)2 but neither these processes lie within the carbonation conditions explored in this work
  • In a recent study on sulphation under oxy-fired conditions evidence was advanced for the transient formation of Ca(OH)2, with an effect on carbonation (Wang et al., 2008)
  • The addition of steam seems to result in the creation of larger pores
sorbent decay temperature
Sorbent Decay - Temperature

250-425 micron Havelock calcined at 850 C with N2, carbonated with 8% CO2, 21% H2, 42% CO, 17% H2O, and 12% N2

sorbent morphology
Sorbent Morphology

After 10 cycles of calcination/carbonation

Calcined at 850 C with N2 and carbonated at 580 C with 8% CO2, 21% H2, 42% CO, 17% H2O, and 12% N2

Calcined at 850 C with N2 and carbonated at 580 C with 8% CO2, 17% H2O, and 75% N2

sorbent morphology21
Sorbent Morphology

After 10 cycles of calcination/carbonation

Calcined at 850 C with N2 and carbonated at 580 C with 8% CO2, 21% H2, 42% CO, 17% H2O, and 12% N2

Calcined at 850 C with N2 and carbonated at 580 C with 8% CO2, 17% H2O, and 75% N2

calcination
Calcination
  • Under a 90% percent atmosphere of CO2, the initial rate of carbonation is 1/5 that of calcination with pure N2.
  • It is known that during sintering, necks develop between adjacent micrograins and continue to grow. The material for this is supplied from the rest of the micrograin, so that the distance between grain centers is diminished. This causes both the voidage and the surface area to decrease (Stanmore and Gilot, 2005).
sorbent morphology23
Sorbent Morphology
  • Images after first calcination/carbonation cycle
  • Calcined at 915 C and carbonated at 620 C with 8% CO2, 21% H2, 42% CO, 17% H2O, and 12% N2

Calcined under N2; kept under CO2 until temperature ready for calcine

Calcined under 90% CO2; balance N2

co 2 looping cycle pilot plant

Fresh

Loaded

Regenerated

Low CO2 (< 5%)

High CO2 (~92%)

Air

Oxygen

Coal

Coke

CO2 Looping Cycle Pilot Plant

Sorbent

Carbonator

Fuel

Flue Gas

Air Blown

Combustor

Oxy-Fuel CFB

Calciner

Oxidant

our small oxy fuel cfbc
Our small oxy-fuel CFBC
  • Current Configuration
    • 5 m in height, 0.1 m ID
    • 18 kW of electric heaters surrounding dense bed region
    • Primary and secondary oxidant ports with flue gas dilution
    • Independent fuel and sorbent injection
    • Recycle system includes condenser, condensate KO, and blower
    • Utilities include steam, water & air
    • Fluidizing gas 65+ mol% O2
    • BFB or CFB
oxy fired circulating fluidized bed cfb
Oxy-Fired Circulating Fluidized Bed (CFB)
  • 10 m; 0.6 m ID
  • Maximum oxygen flow 250 kg/hr
  • Currently set up for a maximum oxygen concentration of 27 mol%
  • 1 m BFB adjacent with solids transport lines
  • BFB opeated as a gasifier or combustor
  • Previously operated as an Exxon style fluid bed coker (5 years)
  • Proposal submitted for CO2 looping in this facility
effect of hydration
Effect of Hydration
  • Hydrated Cadomin limestone derived sorbent conversion to CaCO3 at various conditions
  • Conversion as high as 0.57 after 20 cycles
  • Sorbent was likely too friable for commercialization
  • No SO2 in sample gases
  • Calcined in N2
sorbent pelletization
Sorbent Pelletization

Conversion

Cycle Number

pilot scale work summer 2008
Pilot Scale Work Summer 2008

Objective

  • Investigate CO2 capture processes at pilot scale under atmospheric pressure; flue gas & syngas

Experimental equipment

  • Batch or continuous operations in 0.1 m ID fluidized beds
  • Calcine with oxy-fired wood pellets with recycled flue gas (dry recycle, O2 up to 65 mol%)
  • Carbonate with mildly fluidized or moving bed gas velocities
  • Rotary tube furnace
    • Pretreatment or periodic treatment
    • Max 1400 C; 21 kW
    • 1 m heated length; 1 - 5 rpm
    • Can add steam etc. to heated zone

Early results

  • Tests to date with air/CO2/H2O
  • Steam allowing CO2 capture at equilibrium levels even below 580 C
contact
Contact

Robin Hughes, CANMET

rhughes@nrcan.gc.ca

Dr. E. J. Anthony, CANMET

banthony@nrcan.gc.ca