Results from test campaigns at the 1 t/h CO2 PCC pilot plant in Esbjerg under the EU FP7 CESAR project

Jacob Nygaard Knudsen, Jimmy Andersen, Jørgen N. Jensen – DONG Energy

Ole Biede – Vattenfall

IEAGHG - 1st Post Combustion Capture Conference

17-19 May 2011, Abu Dhabi

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CESAR Project Consortium

R&DIFP (FR)TNO (NL)SINTEF (NO)NTNU (NO)POLYMEN (FR)CNRS (FR)U. KAISERSLAUTERN (DE)

Oil & GasSTATOILHYDRO (NO)GDF (FR)

Power CompaniesDONG Energy (DK)VATTENFALL (SE/DK)E.ON (DE/UK)ELECTRABEL (BE)RWE (DE/UK)PPC (GR)POWERGEN (UK)

ManufacturersALSTOM POWER (SE)DOOSAN BABCOCK (UK)SIEMENS (DE)BASF (DE)

Coordinator: TNO

CESAR: CO2 Enhanced Separation And Recovery

3-year EC sponsored project (2008 – 2011) in the 7th Framework Programme

Aim: To reduce the cost of CO2 post-combustion capture

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Objectives with Pilot Plant Testing in CESAR

Evaluate the potential of reducing the energy consumption of CO2 capture through advanced absorption/desorption process configurations in pilot-scale

Evaluate the potential of reducing the regeneration energy through use of novel amine solvents

Determine the performance of a benchmark solvent (MEA) and two novel solvents at realistic operation conditions for future full-scale application in coal-fired power plants

Monitor actual solvent degradation, losses and by-products, corrosion and emissions for benchmark and novel solvents

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Esbjerg 1t/h CO2 Capture Pilot Plant

Esbjerg Pilot Plant details

Located at a coal-fired power station in Esbjerg, Denmark

Erected and commissioned in 2005 (CASTOR)

Operates on a slip stream of flue gas taken directly after the wet FGD

Flue gas flow: 5000 Nm3/h (0.5% of 400 MWe)

CO2 capture capacity: 1000 kg/h

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Flue gas from power plant

Mechanical filters

Lean MEA

Rich MEA

Steam

Treated flue gas

CO2 Out

Cooling water circuit

Reboiler

MEA/MEA heat exchangerABSORBER STRIPPER

Condensate

Wash section

Esbjerg Pilot Plant Flow Diagram

Revamping of absorber with structured packing

Expansion of cross flow heat exchanger

Absorber inter-cooling

Installation of vapour recompression

Fresh water

Bubble cap polisher

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CESAR Test Programme at Esbjerg Pilot Plant

The selected pilot plant modifications were installed during 2008. Afterwards, three test campaigns were conducted:

Benchmark solvent: >1000 hours with ”30%-wt. MEA” (Mar 2009 – July 2009)

1st novel solvent: >1000 hours with blend of AMP & piperazine (PZ) ”CESAR 1”

(Nov 2009 – Feb 2010)

2nd novel solvent: • 200 hours with 30%-wt. ethylenediamine (EDA) ”CESAR 2”

(Mar 2010 – Jun 2010)

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Detailed Outline of Test Campaigns

Parameter variation tests:

500 hours of continuous operation

Miscellaneous tests

1A) Optimisation of solvent flow rate (at 90% capture)1B) Optimisation of inter-cooler temperature (at 90% capture)1C) Optimisation of flash pressure (at 90% capture)2) Variation of reboiler steam input at optimum solvent flow3) Variation of stripper pressure (at 90% capture)

- Operation at ”optimised” conditions- Achieving 90% CO2 capture (on average)- Quantification of solvent consumption and degradation- Characterisation of corrosion behaviour

- Emission measurements!- Absorber pressure drop measurements- Load following capability and transient tests

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Revamping of AbsorberD

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Absorber packing changed from IMTP50 random packing to Mellapak 2X structured packing

New liquid distributors

Installation of bubble cap tray on top of wash section

Results:

Absorber • P decreased from • 600 to • 300 mm H2O at 5000 Nm3/h (includes • P of 20-40 mm H2O new bubble cap tray)

No significant impact on mass transfer with MEA

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Improved Rich/Lean Heat ExchangerD

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New Rich/lean heat exchanger with increased

capacity installed

Heat transfer area increased with 35%

Results:

• T (pinch side) decreased from 7.1-8.0 to 4.0-

4.3oC depending on L/G which is equal to • 0.2-

0.3 GJ/ton CO2 more sensible heat being

recovered

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Optimisation of Absorber L/G with Improved Rich/Lean HX

30% MEA benchmark, stripper pressure 0.85 barg, flue gas flow • 5000 Nm3/h and • 90 % CO2 recovery

∆T = 4.0-4.3ºC

50

60

70

80

90

100

3,0

3,2

3,4

3,6

3,8

4,0

2,0 2,5 3,0 3,5 4,0

CO

2re

cove

ry (

%)

Ste

am c

on

sum

ptio

n (G

J/to

n C

O2)

Absorber L/G ratio (kg/kg)

Steam consump. CO2 recovery

CASTOR: ∆T = 7.1-8.0ºC

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Single Stage Absorber Inter-coolingD

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Inter-cooler installed between first and second

bed from the bottom

Solvent may be cooled down to • 25oC

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Effect of Absorber Inter-cooling

30% MEA benchmark, Flue gas flow • 5000 Nm3/h, L/G • 3 kg/kg, Stripper pressure =0,85 barg, CO2 capture • 90%

Solvent 40ºCFlue gas 48ºC

50

60

70

80

90

100

3,0

3,2

3,4

3,6

3,8

4,0

20 30 40 50 60

CO

2re

cove

ry (

%)

Ste

am c

on

sum

ptio

n (G

J/to

n C

O2)

Inter-cooler temperature (oC)

Steam consump. CO2 capture

25

35

45

55

65

75

0 4 8 12 16 20

Ab

s. te

mp

erat

ure

(oC

)

Packing height (m)

58,1 45,0 37,5 30,0 24,9

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Lean Vapour RecompressionD

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Hot lean solvent from the stripper is flashed

The vapours are compressed by a mechanical

compressor and injected in the stripper bottom

The liquid phase from the flash enters the

rich/lean heat exchanger

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Effect of Lean Vapour Recompression

Flue gas flow: 5000 Nm3/h, Solvent flow 18 m3/h, Stripper pressure (top): 0.85 barg

0

10

20

30

40

50

2,6

2,8

3,0

3,2

3,4

3,6

3,8

4,0

0,0 0,2 0,4 0,6 0,8 1,0

Incr

ease

d p

ow

er c

on

sum

p. (

kWh

/ton

CO

2)

Ste

am c

on

sum

ptio

n (G

J/to

n C

O2)

Flash pressure (barg)

Steam Power Isentropic Power

Steam consumption reduced significantly....But increased electricity consumption!!!

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Test Campaigns with Novel Solvents

Two novel solvent systems was developed in the CESAR project and brought to testing in Esbjerg:

CESAR 1: 3 M AMP + 2 M PZ

CESAR 2: 5 M EDA

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Comparison of Regeneration Energies

Flue gas flow = 5000 Nm3/h, Pstripper = 1.85 bara, CO2 • capture 90%, No inter-cooling, No LVC

3,0

3,2

3,4

3,6

3,8

4,0

1,0 1,5 2,0 2,5 3,0 3,5 4,0

Ste

am c

on

sum

ptio

n (G

J/to

n C

O2)

L/G (kg/kg)

MEA CESAR 1 CESAR 2

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Comparison of Solvents – Influence of Inter-Cooling

2,7

2,9

3,1

3,3

3,5

3,7

20 30 40 50 60

Stea

m c

onsu

mpt

ion

(GJ/

ton

CO

2)

Inter-cooler temperature (oC)

MEA CESAR 1 CESAR 2

Saving • 0.2 GJ/ton or 7%

Saving • 0.1 GJ/ton or 3%

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Comparison of Solvents – Influence of Vapour Recompression (1)

2,6

2,8

3,0

3,2

3,4

3,6

3,8

0,0 0,2 0,4 0,6 0,8 1,0

Ste

am c

on

sum

ptio

n (G

J/to

n C

O2)

Flash pressure (barg)

MEA CESAR 1 CESAR 2

0.7 GJ/ton or 20% reduction

0.4 GJ/ton or 13% reduction

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Comparison of tests – Influence of Vapour Recompression (2)

0

10

20

30

40

0,0 0,2 0,4 0,6 0,8 1,0

Po

wer

co

nsu

mpt

ion

(kW

h/to

n C

O2)

Flash pressure (barg)

MEA CESAR 1 CESAR 2

0

5

10

15

20

25

0,0 0,2 0,4 0,6 0,8

Sav

ing

((kW

ste

am/ k

W p

ow

er)

Flash pressure (barg)

MEA CESAR 1 CESAR 2

Reported values are actual power consumptions. The power consumption may be reduced by use of more efficient compressors

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Summary of Improvements with MEA, CESAR 1 and CESAR 2

Conditions: Flue gas flow 5000 Nm3/h, Optimal L/G, CO2 removal • 90% , Stripper pressure 1.85 bara

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

Standard Improved Hx Improved Hx+IC Improved Hx+LVR Improved Hx+IC+LVR

Spec

ific

stea

m c

onsu

mpt

ion

(GJ/

ton

CO2)

MEA CESAR 1 CESAR 2

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It is not just Energy Consumption...

Other aspects than energy consumption are important when considering new amine solvents:

•Corrosion issues/material selection

•Solvent consumption and degradation

•Operating/Handling issues

•Environmental impact

•......

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Corrosion Issues – Build-up of Iron in Solvent

0

1

10

100

1000

0 200 400 600 800 1000 1200

Fe c

onte

nt o

f sol

vent

(mg/

l)

Operating hours (full load hrs.)

MEA CESAR 1 CESAR 2

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Comparison of Solvent Consumptions

Main sources of solvent loss:

MEA : Loss mainly due to degradation

CESAR 1: Loss mainly due to emission (AMP) and absorption of SO2

Solvent AmountMEA* : 2.3 kg/ton CO2

CESAR 1: AMP 0.73 kg/ton CO2

PZ 0.15 kg/ton CO2

CESAR 2: Seemingly low, not quantified!

Consumption numbers based on 500 hours continuous testing

*Previously measured MEA losses: 1.4-2.4 kg/ton CO2

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Comparison of build-up of Heat Stable Salts (Degradation)

0

0,2

0,4

0,6

0,8

1

1,2

0 200 400 600 800 1000 1200

Hea

t sta

ble

salt

s (%

-wt)

Operating hours (full load eqv. hrs.)

CESAR 1 MEA

CESAR 1: • 80% of HSS formation due to absorption of SO2 and HCl!

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Emission Measurements at Esbjerg

Pioneering work regarding emission characterisation has been conducted at Esbjerg as part of the CESAR project:

Challenge: No standard sampling methods for amines and (most) amine degradation products in flue gas streams (high moisture content)

Iso-kinetic sampling of flue gas at inlet and outlet from CO2 absorber

Quantification of emissions of various inorganic and organic species

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Determination of Inorganic Emissions

Emission results using MEA

Compound Unit Inlet Outlet CO2 mg/Nm3 13.2 1.7 CO mg/Nm3 9.8 12.4 HCl mg/Nm3 0.06 < 0.04 HF mg/Nm3 < 0.04 < 0.04 SO2 mg/Nm3 14.4 1.5 NOx mg/Nm3 27.5 34.4 TOC mg/Nm3 < 2 < 2 Particulate mg/Nm3 2.1 < 1.2 Al µg/Nm3 75 < 2 Ca µg/Nm3 88 < 1 Fe µg/Nm3 49 < 1 Si µg/Nm3 140 < 8

Pilot plant operated at steady state

conditions with bubble cap polisher

Flue gas outlet temperature • 50oC

Measurements based on 2-hours

sampling periods

Both CEMs and wet chemical methods

are applied

Indicates that emissions of coal fly ash are significantly reduced!!

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Determination of Organic Emissions

Pilot plant operated at steady state

conditions with and without bubble cap

polisher

Flue gas outlet temperature • 50oC

Measurements based on 2 x 1-hours

sampling periods

Emission results under MEA operation (mg/Nm3)

Abs. inlet Abs. outlet Compound - No polisher polisher Formaldehyde < 0.1 0.7 < 0.1 Acetaldehyde 0.2 1.1 0.8 Acetamide < 0.6 < 1.0 < 1.0 MEA < 0.1 0.7 < 0.3 DEA < 0.2 < 0.3 < 0.2 Methylamine < 0.2 < 0.3 < 0.2 Ethylamine < 0.2 < 0.3 < 0.2 Dimetylamine < 0.2 < 0.3 < 0.2 Ethylenediamine < 0.2 < 0.3 < 0.2 NH3 < 0.1 23 20 VOC 0.7 4.1 0.5 Nitrosamines ? ? ?

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Summary Novel Solvents

CESAR 1

Good energy efficiency and high CO2 cyclic capacity

Excellent chemical stability, low corrosiveness, can be thermally reclaimed

Downsides: Volatility (AMP), nitrosamine formation (PZ), biodegradability and costs!

CESAR 2

Moderate energy efficiency and cyclic capacity (slightly better than MEA)

Good chemical stability and relatively low volatility

Downsides: EDA is very corrosive!

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Conclusions Pilot Plant Testing

A series of process upgrades have been implemented at the Esbjerg 1t/h pilot plant and test campaigns with MEA and two novel solvents have been conducted. Main findings:

Energy consumption could be reduced with up to 25% i.e. from 3.7 to 2.8 GJ/ton (CESAR 1 + Inter-cooling)

The reboiler duty of the "classical" 30% MEA process can be significantly reduced by LVR (3.6 to 2.8 GJ/ton) on account of increased auxiliary power consumption. The true benefit of LVR will be site specific

Combination of process optimisation and novel solvents leads to significant energy savings. However, the impact of process upgrades is very solvent dependent.... process design and solvent development go hand in hand!

New knowledge on emissions of potentially harmful components have been obtained, but there is still a lot to do!