Concentrated PiperazineConcentrated PiperazineA new standard solvent

by GGary T. Rochelle

gtr@che.utexas.edu Luminant Carbon Management ProgramLuminant Carbon Management Program

Department of Chemical Engineering The University of Texas at Austiny

September 30, 2010

Why 8 m (40 wt% Piperazine?

• 10-20% less energy than 30 wt% MEA– 2 x CO mass transfer rate– 2 x CO2 mass transfer rate – 1.8 x capacity– High P (6 – 15 atm) Stripper, stable to 150°C

• Oxidatively stable, esp. with Inhibitor Ay , p• Less volatile than 7 m MEA

S l bl 0 C i l di• Soluble at 0oC at operating loading• Good Opportunities for Reclaimingpp g

Roadmap

• Energy Properties• Solvent ManagementSolvent Management• Pilot Plant

Energy Properties• Chemistry 2 active amines per molecule• Chemistry – 2 active amines per molecule• Viscosity & Solubility allow 8 m PZ when loaded• CO2 solubility

– Capacity – 0.84 moles/kg solvent– Heat of Desorption – 76 kJ/mole

• Thermal Stability to 150oCe S b y o 50 C• 2-stage heated flash reduces energy 15%

Solubility Envelope for PZ

H PZCOO H O ( )Aqueous PZ

H+PZCOO-·H2O (s)qSolution

10 m PZ

8 m PZ Expected loading range

PZ·6H2O (s)

5CO2 Capture with of Concentrated Aqueous PZ

Viscosity Comparison

40°C, αrich 10 m PZ40 C, αrich 10 m PZ

13.7 m DGA

7 m MDEA/2 m PZ7 m MDEA/2 m PZ

7 m MDEA 7 m PZ

8 m PZ

8 m PZ has lower viscosity with higher alkalinity than DGA7 m MEA

7 m MDEA

6CO2 Capture with of Concentrated Aqueous PZ

CO2 solubility in Aqueous PZ

1.E+06

1.E+07

80

85

160oC

ΔHCO222

Q1.E+05

ar)

70

75

mol

)

160 C

120

6

1

reb (

1.E+04

P CO

2 (ba

65

70

Hab

s (kJ

/m

800.05(kJ/mol1.E+02

1.E+03

P

55

60 ΔH

400.005

0 84 mol CO /kg solvent ol)

1.E+01

1.E 02

50

550.84 mol CO2/kg solvent(0.48 for MEA)

0.20 0.25 0.30 0.35 0.40 0.45CO2 loading (moles/equiv PZ)

CO2 Absorption Rate, 40oC1E-05

8 PZ

a. m2 ) 8 m PZ Operating

Range

1E-06

ol/s

. Pa

7 m MEA

k g' (

mo

8 m 2-PE1E-07

10 100 1000 10000

k 8 m 2-PE

5%0.5%P*CO2 @ 40C (Pa)

5%0.5%

Thermal Degradation at Rich Loading100

k)g g

Ea=133 kJ/mol

10

%/w

eek

Loss (% 7 m MEA 8 m PZ

1

Amine L

10 m PZ

0.1

A

135100 175150120 oT (oC)

Ldg=0.31

3-Stage Flash3-Stage FlashLdg = 0.41

Stripping 8 m PZ

160 kPa

160 kPa

ΔT=5oCRich P*CO2=5 kPa

150oC

comppumpreb

sinkrebrebeq W

KTTKTQW /10

1075.0 +⎥⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+

−+⋅= ∑

Solvent Management

• Volatility <20 ppm at lean conditions– Air Impacts minimized by Water Wash

• Oxidation 3 x less than MEA- Eliminated by inhibitor A

• 316 SS resistant to corrosion316 SS resistant to corrosion• Piperazine easily reclaimed by existing options

SS316 corrosion in thermal degradation experimentsdegradation experiments

167 m MEA, 135°C

12

14

mM

)

,(6.7% loss/wk)

Fe & Ni

8

10

atio

n (m

8 m PZ 150°C

4

6

once

nt 8 m PZ, 150°C(0.4% loss/wk)

Fe & Ni

0

2

4C Fe & Ni

22CO2 Capture with of Concentrated Aqueous PZ

0

0 5 10 15 20Time (weeks) (Voice 2009)

Reclaiming concepts• Traditional Thermal or distillation Reclaiming

Atm or vacuum– Atm or vacuum– PZ more volatile than MEA

PZ th ll t bl– PZ thermally stable• Inhibitor A recovered from conc soln by supplier• Ion Exchange or electrodialysis as with MEA• K2SO4 crystallization with addition of KOH2 4 y

– 0.17 m sulfate solubility

Pilot Plant

• Results in 0.1 MW with air/CO2– Mass Transfer RateMass Transfer Rate– Energy

• Plans for 0 1 MW with high P 2 stage flash• Plans for 0.1 MW with high P 2-stage flash

Selected Pilot Plant Runs, 8 m PZ20 ft Mellapak 2X 200m2/m320 ft Mellapak 2X, 200m /m

Gas Liq PSTRP Rem Lean Rich(acfm) (gpm) (psia) (%) Ldg Ldg

350 18 51 93.2 0.27 0.34350 18 51 93.2 0.27 0.34

350 15 20 93.4 0.25 0.33350 15 20 93.4 0.25 0.33

350 18 20 79.3 0.30 0.36350 18 20 79.3 0.30 0.36

350 15 60 76.1 0.31 0.36

Loading = mol CO2/Total Alkalinity

Wetted wall kg’ & Pilot plant KG

9m PZ

8 PZ 60 C

9m PZ8m PZ

8m PZ 40oC

8m PZ 60oC 5m PZ

7 5m PZ7.5m PZ

5m K+/2.5m PZ 7m MEA

6.4m K+/1.6 m PZ9 m MEA

7m MEA

6/15/2009 The University of Texas at Austin 26

Stripper PerformanceStripper Performance

*Yokoyama T. 2004. Japanese R&D on Large-Scale CO2 Capture. 2004 ECI Conference on Separations Technology VI: New Perspectives on Very Large-Scale Operations. Fraser Island, Queensland, Australia

6/15/2009 27The University of Texas at Austin

Conclusions

• 10-20% less energy than 30 wt% MEA– Double the CO2 mass transfer rate – 1.8 x capacity– High P (6 – 15 atm) Stripper, stable to 150°C

• Oxidatively stable esp with Inhibitor A• Oxidatively stable, esp. with Inhibitor A• Less volatile than 7 m MEA • Soluble at 0oC at operating loading• Soluble at 0oC at operating loading• Good Opportunities for Reclaiming