Absorptive  Technologies  for  Carbon  Capture  for  the  Iron  &  

Steel  sector  

A.K.  Suresh  Indian  Institute  of  Technology  Bombay  

Mumbai,  India  –  400  076  

19/10/14   A.K.  Suresh  |  IIT  Bombay   2/21  

Contents  

Contents

l  CO2 emissions and the Iron & Steel sector l  Absorptive Technologies for CO2 capture

l  Some strategies to improve the economics of CCS in

the industry

l  Conclusions

19/10/14   A.K.  Suresh  |  IIT  Bombay   3/21  

CO2  Emissions  &  the  Steel  sector  

Emissions – Steel sector

Industry

CO2 emissions [million tons] Reference India World#

Steel 144.4* [~8.4 %]

~2980.1* [~9.1 %]

World Steel Association 2011

Overall 1725.7 32578.6 EIA 2011

•  Iron and Steel: the largest emitter of CO2 in the manufacturing sector –

•  Energy intensive nature of the industry •  Reliance on fossil carbon for fuel & reductants •  Size of the industry

Source:  Pro$iles,  No.  12(1),  IEA  Clean  Coal  Centre,  Feb  2012     4/21  

Source  apportionment  

Emissions -Steel sector

19/10/14   A.K.  Suresh  |  IIT  Bombay   5/21  

CO2  concentrations:  Steel  vs  other  sectors  

Emissions -Steel sector

Source of flue gas CO2 concentration (%) Pulverized coal power plant 13-15

NGCC power plant 3-9

IGCC power plant using coal slurry 7 Steam reformer 8 Petrochemical plant 7 Steel mill 25 Cement plant 30

•  CO2 concentration the gas stream influences the choice of capture technology

Source: Lee and Sircar (2008)

19/10/14   A.K.  Suresh  |  IIT  Bombay   6/21  

Absorption  technologies  for  CO2  capture  

Absorption Technologies

u  Fairly mature; Physical and Chemical solvents; choice of technology depends on Ø Solvent capacity for CO2 Ø Rate of absorption Ø Cost in terms of energy requirement and efficiency penalty

u  Possibilities for innovation – Ø Newer solvents, more efficient hardware Ø Use of waste products of the industry for capture and

recycling Ø Novel strategies for process intensification

19/10/14   A.K.  Suresh  |  IIT  Bombay   7/21  

Absorption:  Physical  vs  Chemical  

Absorption Technologies

Physical Absorption Chemical Absorption Based on solubility of CO2 in solvent – works better at high pCO2

Based on reaction of CO2 with the solvent – can work at low pCO2, but capacity limited by reactant

Regeneration is by pressure swing – less energy intensive

Regeneration by increasing temperature – energy intensive

Tolerant to oxides and other impurities Forms stable salts with oxides

Solvents: Rectisol, Selexol etc. Solvents: Alkanolamines, NH3 etc.

19/10/14   A.K.  Suresh  |  IIT  Bombay   8/21  

Absorption  Technologies  

Absorption Technologies

Physical

Chemical

l  Fluor Econamine (MEA) l  MHI KS-1, KS-2 (Hindered amines) l  Chilled Ammonia (NH3) l  Shell Carbonate (K2CO3) l  Others

l  Rectisol (Methanol) l  Selexol (PEG derived ethers) l  Others

Low Regeneration energy vapor pressure byproduct formation viscosity corrosion rate

High Absorption capacity Absorption rate Thermal and Chemical stability

Desired:

Feasible for higher than 15% CO2 Rectisol gives higher loading than chemical solvents for pCO2> 4 atm

19/10/14   A.K.  Suresh  |  IIT  Bombay   9/21  

Solvent  Characteristics  

Absorption Technologies

Source: Pandurean et al (2013), Bailey & Feron (2005)

Property Unit Rectisol Selexol MEA DEA MDEA

Concentration % Wt - - 30 40 50 Molecular Weight g/g mole 32 280 61.09 105.14 119.17 pH , 20 ºC - - - 12.1 11.0 11.5 Vapor press., 20 ºC mmHg 125 0.00073 0.36 0.01 0.10 Abs. Viscosity, 20 ºC cP 0.6 5.8 24.1 380 101 Typical loading mole/mole - - 0.3 0.3-0.7 0.45 Heat of absorption MJ/kg of CO2 - - 2.0 1.5 1.3

Rate constant, 25 ºC m3/kmole.s - - 7600 1500 5

Chemical solvents: MDEA/hindered amines better in terms of energy Physical solvents may be competitive for high pCO2

19/10/14   A.K.  Suresh  |  IIT  Bombay   10/21  

EfViciency  Penalty  

Energy/efficiency cost

Source: Goto et al (2013)

l  Cost of electricity can increase significantly. l  Regeneration energy is clearly high for Econamine FG+ (MEA) compared to

CANSOLV (tertiary) or KS-1 (hindered); physical solvents attractive from this perspective

19/10/14   A.K.  Suresh  |  IIT  Bombay   11/21  

Steel  Industry  wastes  –  Potential  carbon  capture  agents  

Strategies -1

Solid/Liquid Waste Qty (kg/t)

Capture Potential+ (kg/t)

Source of generation

Blast furnace slag 340-421 100-124 Blast furnace BF flue dust 28 0.7 Blast furnace LD* slag 200 78.6 Steel melting shop LD sludge 15-16 1.1-1.2 Steel melting shop Flyash - - Power plant

Source: B.Das et al (2007) *LD: Linz-Donawitz + Based on CaO content

Sequestration/recycle potential : About 9-10% of the CO2 generated

19/10/14   A.K.  Suresh  |  IIT  Bombay   12/21  

Slag  carbonation  routes  

Strategies -1

19/10/14   A.K.  Suresh  |  IIT  Bombay   13/21  

Additional  possibilities  Strategies -1

§ Use of alkaline wastewaters as physical solvents

§ Use of extraction agents which can leach Ca from silica matrix

§ Use of phenolic wastewater from coke oven – §  Precipitation of Ca § Recovery of phenol and recycle of lime

19/10/14   A.K.  Suresh  |  IIT  Bombay   14/21  

Process  intensiVication  with  nanoparticles  

Strategies -2

l  OBSERVATION: l  Nanoparticles in suspension enhance mass transfer rates in gas-

liquid mass transfer

l  MECHANISM: l  A microconvection effect caused by the Brownian motion of

nanoparticles (?) l  A correlational approach provides a design basis.

l  IMPLICATIONS: l  Would favorably influence rate in absorption as well as desorption!

Mass  transfer  in  nanoVluids    Studies  in  model  apparatus  

19/10/14   A.K.  Suresh  |  IIT  Bombay  

Wetted wall column

Absorption capillary

Systems: Gas : CO2 Particles: Fe3O4, SiO2, TiO2 Solvents: Water

MEA, MDEA

Observations: §  Enhancement in rate §  Extent depends on ü Basic mass transfer rate ü Relative size of particle to

solute penetration depth ü Density of particles ü Volumetric hold-up

Strategies -2

15/21  

u = u(Re p ,Sh,ε )

Mass  transfer  in  nanoVluids    Explaining  the  observations  

19/10/14   A.K.  Suresh  |  IIT  Bombay  

§  Brownian motion of nanoparticles a net advective motion in the direction of transfer;

Correlation of results:

Re p =dpvBrownρ p

µSh =

klrxndpD

=(klEc )dp

D ε = particle vol fraction

Strategies -2

16/21  

Mass  transfer  in  nanoVluids    Test  of  the  correlation  in  a  packed  bed  

19/10/14   A.K.  Suresh  |  IIT  Bombay  

Strategies -2

6.0E-05

8.0E-05

1.0E-04

1.2E-04

1.4E-04

1.6E-04

0 0.001 0.002 0.003 0.004 0.005

Exp

t. kl

(m/s

)

ε Volume fraction of NP

L=227 ml/min

L=146 ml/min

L=304

Results from physical absorption studies (12 nm silica):

17/21  

Mass  transfer  in  nanoVluids    A  design  basis  

19/10/14   A.K.  Suresh  |  IIT  Bombay  

Strategies -2

10

1

kl ×104

18/21  

Mass  transfer  in  nanoVluids    A  design  basis  (e.g.  silica  in  water)  

19/10/14   A.K.  Suresh  |  IIT  Bombay  

Strategies -2

10

19/21  

Summing  up  

19/10/14   A.K.  Suresh  |  IIT  Bombay  

§  Economics of CCS – a deterrent for deployment

§  Steel industry wastes offer possibilities to capture CO2 and recycle adjuvants

§  Use of novel strategies to improve rates of absorption and recovery of CO2 have shown promise

Conclusions

Acknowledgments  

19/10/14   A.K.  Suresh  |  IIT  Bombay  

§  Doctoral students §  Ratnesh Khanolkar (Nanofluids work) §  Raghavendra Ragipani (Steel slags etc).

§  Funding received §  CCCU funding to develop the nanofluids

strategy §  Jindal (JSW) support for exploring

applications to steel industry

Acknowledgments