A low energy Chilled Ammonia Process exploiting …€¦ · Institute of Process Engineering | |...

Daniel Sutter, Matteo Gazzani, José-Francisco Perez-Calvo, Marco Mazzotti Institute of Process Engineering, ETH Zurich

PCCC-3, September 8-11, 2015

A low energy Chilled Ammonia Process exploiting controlled solid formation: holistic development from thermodynamics to kinetics

| | Institute of Process Engineering 13-Sep-15 Daniel Sutter, [email protected] 2

Hype cycle for NH3-based CO2 capture

[7] Bollinger et al. Alstom Technical Report, Paper No. 72 [8] Darde et al. Int J Greenh Gas Control, 10 (2012) 74-87 [9] Black et al. (2013) Patent No. US 2013/0028807 A1 [10] Darde et al. Ind Eng Chem Res. 49 (2010) 12663-12674) [11] Que and Chen. Ind Eng Chem Res. 50 (2011) 11406-11421 [12] Baburao et al. Presentation at TCCS-8, Trondheim, Norway

• understand • control • exploit solid formation in the CAP.

Research objectives

[1] Bai and Yeh. Ind Eng Chem Sc. 36 (1997) 2490-2493 [2] Bai and Yeh. Sci Total Environ. 228 (1999) 121-133 [3] Gal. (2006) Patent No. WO2006/022885A1 [4] Mathias et al. Energy Procedia 1 (2009) 1227-1234 [5] Mathias et al. Int J Greenh Gas Con 4 (2010) 174-179 [6] Yu et al. Chem Eng Res and Des. 89 (2011) 1204-1215

Motivation

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Thermo- dynamics

Kinetics Process

Synthesis Process

Optimization Process

Integration

13-Sep-15 Daniel Sutter, [email protected] 3

Holistic development

Motivation Thermodynamics


Understanding the system thermodynamics



System is governed by strong interdependencies

adapted from: Darde et al., Ind Eng Chem Res 49 (2010) 12663-74



Phase diagram construction

wt. frac.




10°C

1 bar

Thermodynamic model: Thomsen and Rasmussen. Chem Eng Sci. 54 (1999)1787-1802 Darde et al., Ind Eng Chem Res. 49 (2010) 12663-74 Solid properties: Jänecke, Z Elektrochem. 35 (1929) 9:716-28




1 bar



Criticalities in the process

Sutter et al. Chem Eng Sci. 133 (2015) 170-180



CO2 absorber

CO2 depleted flue gas

Pump- around

CO2-lean solution

CO2-rich solution

Cooled flue gas

Bollinger et al. Alstom Technical Report, Paper No. 72 Darde et al. Int J Greenh Gas Control, 10 (2012) 74-87 Black et al. Patent No. US 2013/0028807 A1 Sutter et al. Chem Eng Sci. 133 (2015) 170-180



CO2 absorber – exemplary simulation


Pump- around

CO2-lean solution

CO2-rich solution

Cooled flue gas

Feed



Thermo- dynamics

Kinetics Process

Synthesis Process


Integration



Kinetics Motivation Thermodynamics


Kinetics – equilibrium and rate-controlled reactions

(1) Self-ionization of water

(2) Dissociation of bicarbonate

(3) Protonation of ammonia

(4) Bicarbonate ion formation

𝐇𝟐𝐎𝐊𝟏 𝐎𝐇− + 𝐇+

𝐇𝐂𝐎𝟑−𝐊𝟐 𝐂𝐎𝟑

𝟐− +𝐇+

𝐍𝐇𝟑 +𝐇𝟐𝐎𝐊𝟑 𝐍𝐇𝟒

+ + 𝐎𝐇−

𝐂𝐎𝟐 + 𝐎𝐇−𝐤𝟒,𝐤−𝟒,𝐊𝟒

𝐇𝐂𝐎𝟑−

(5) Carbamate ion formation

Equ

ilib

riu

m

rea

ctio

ns

Dif

fusi

on

an

d r

ate

co

ntr

oll

ed

re

act

ion

s

𝐂𝐎𝟐 + 𝐍𝐇𝟑𝐤𝟓,𝐤−𝟓,𝐊𝟓

𝐍𝐇𝟐𝐂𝐎𝐎− +𝐇+



Bicarbonate ion formation

carbonic acid dissociation CO2 + H2O HCO3

− + H+ negligible contribution for pH>8 [4]

reaction with hydroxide ion CO2 + OH− HCO3

−

Carbamate ion formation

Zwitterion mechanism[5,6]

Zwitterion formation CO2 + NH3 NH3

+COO−

deprotonation NH3+COO− + B

NH2COO

− + BH+ often considered non-rate-limiting[1-3]

Termolecular mechanism[7,8] CO2 + NH3 + B NH2COO

− + B

Elementary reactions mechanism[9]

CO2 + NH3 NH2COO

− + H+


Kinetics – chemical reaction mechanisms

[1] Pinsent et al. Trans Faraday Soc. 52 (1956) 1594-1598. [2] Pinsent et al. Trans Faraday Soc. 52 (1956) 1512-1520. [3] Puxty et al. Chem Eng Sci. 65 (2009) 915-922. [4] Blauwhoff et al., Chem Eng Sci. 39 (1984) 207-225. [5] Caplow. J Am Chem Soc. 90 (1968) 6795-6803.

[6] Danckwerts. Chem Eng Sci. 34 (1979) 443-446. [7] Crooks and Donellan. J Chem Soc Perkin Trans II. 4 (1989) 331. [8] da Silva and Svendsen. Ind Eng Chem Res. 43 (2004) 3413-3418. [9] Wang et al. J Phys Chem. 115 (2011) 6405-6412.



mechanism for carbamate ion formation

zwitterion w/o dissociation[1,3]

zwitterion with limited number of bases [5,6,7]

molecular reaction[4]

termolecular mechanism[7]

importance of bicarbonate ion formation

«bicarbonate formation has limited influence on total absorption»[5]

bicarbonate formation completely neglected[3]

bicarbonate formation is dominant for CO2 loading above 0.5[8,9]

pseudo first order assumption

applied to concentrations of 0.5 wt.% NH3 [1,2]

not fulfilled for experiments at 1 wt.% NH3[5]

Determination of backward reaction rate constants: Thermodynamic models differ

Range of compositions covered by experiments


Differences between kinetic models

[6] Derks and Versteeg. Energy Procedia. 9 (2009) 1139-1146 [7] Qin et al. Int J Greenh Gas Control. 4 (2010) 729-738 [8] Jilvero et al. Ind Eng Chem Res. 53 (2014) 6750-6758 [9] Ahn et al. Int J Greenh Gas Control. 5 (2011) 1606-1613

[1] Pinsent et al. Trans Faraday Soc. 52 (1956) 1594-1598. [2] Pinsent et al. Trans Faraday Soc. 52 (1956) 1512-1520. [3] Puxty et al. Chem Eng Sci. 65 (2009) 915-922. [4] Wang et al. J Phys Chem. 115 (2011) 6405-6412. [5] Darde et al. Int J Greenh Gas Control. 5 (2011) 1149-1162

Pinsent model [1,2]

Qin model [7]

Darde

model [5]

Puxty model

[3]

Derks model

[6] 𝑟 = 𝑘app𝐶CO2

adapted from [5]



Forward reaction rate constant determined experimentally

Backward reaction rate constant: 𝐾 =𝑘+

𝑘− ⟹ 𝑘− =

𝑘+

𝐾


Effect of thermodynamic model on kinetics

Thomsen model[1,2]

extended UNIQUAC

Chen model[3]

e-NRTL

[1] Thomsen and Rasmussen. Chem Eng Sci. 54 (1999)1787-1802 [2] Darde et al., Ind Eng Chem Res. 49 (2010) 12663-74

[3] Que and Chen. Ind Eng Chem Res. 50 (2011) 11406-11421 [4] Sutter et al. Chem Eng Sci 133 (2015) 170-180

[4] [4]




Process simulations represent a drastic extrapolation of the experimental conditions pseudo first order assumption effect of reverse reaction Puxty et al. Chem Eng Sci. 65 (2009) 915-922.

Kim et al. Chem Eng J. 250 (2014) 83-90.



Thermo- dynamics

Kinetics Process

Synthesis Process


Integration



Kinetics Motivation Thermodynamics Process synthesis


A CAP with controlled solid formation

• Solid formation in a dedicated unit

• No solids in packed absorber/stripper columns

Sutter et al. Presentation at PCCC-2. (2013). Gazzani et al. Energy Procedia. 63 (2014) 1084-1090.



Absorber profile: standard vs. crystallizer CAP

0 0,5 1

Co

lum

n s

tag

es

Solubility index

standard CAP crystallizer CAP


Pumparound

CO2 lean solution

CO2 rich solution

Cooled flue gas

Cooled flue gas


Pumparound

CO2 lean solution

CO2 rich solution

Crystallizer CAP

Standard CAP

• Lower working temperature • Better ammonia slip control

bottom

top

• Higher solubility index • Higher CO2 loading (lower flow rate)

Gazzani et al. Energy Procedia. 63 (2014) 1084-1090.



Thermo- dynamics

Kinetics Process

Synthesis Process


Integration



Process opt. Kinetics Motivation Thermodynamics Process synthesis


Single parameter variation vs. system interdependencies

Typical sensitivity analysis with single parameter variation not suitable for optimization

e.g.: NH3 slip vs. NH3 concentration vs. CO2 loading



Heuristic optimization of CAP processes

Design variables Total L/G, incl. recycle CO2 loading lean stream Absorber loading (free NH3 in lean stream/CO2 in FG) NH3 concentration Target parameters NH3 slip, reboiler duty, chilling duty Overall electric penalty (SPECCA) Interpretation and visualization of trends Ternary phase diagrams



Thermo- dynamics

Kinetics Process

Synthesis Process


Integration



Process opt. Kinetics Motivation Thermodynamics Process Integration Process synthesis


CAP is a valid solution for CO2 capture from integrated steelworks

Low reboiler duty makes CAP a very competitive solution for applications with limited steam supply

Since May 2015: CAP for CO2 capture from cement production processes


CAP for integrated steelworks

BFG + COG + BOFG

CO2

CAPby-pass

AIR

1°s 1°r

2°+3°

Power Island

Capture Island

Steel Plant

Fuel blendin

g

Natural Gas

HP MP

Gazzani et al. Presentation. TCCS-8 (2015) Gazzani et al. Poster No. 17. PCCC-3 (2015),

Process opt. Kinetics Motivation Thermodynamics Process Integration Process synthesis


Ammonia-based CO2 capture processes require holistic development

complex reactive system

strong interdependencies

large range of possible operating conditions

large and complex desing space for optimization

wrong focus on single target parameters (reboiler duty) and simplistic «rules of thumb»

Ternary phase diagram approach represents valuable tool for system understanding and optimization

Kinetics

need for further development

review and consolidation of existing models

CAP represents a viable option for post-combustion CO2 capture


Conclusions

Process opt. Kinetics Motivation Thermodynamics Conclusions Process Integration Process synthesis


We acknowledge funding within CTI-project 13973.1 by the Swiss Commission for Technology and Innovation (CTI).


Acknowledgement

A low energy Chilled Ammonia Process exploiting …€¦ · Institute of Process Engineering | |...

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