0
Research Papers: Gas Turbines: Electric Power

# Cyclic Carbonation Calcination Studies of Limestone and Dolomite for $CO2$ Separation From Combustion Flue Gases

[+] Author and Article Information
Sivalingam Senthoorselvan1

Lehrstuhl Energiesysteme, Technische Universität München (TUM), Boltzsmannstrasse 15, 85748 Garching, Germanysivalingam@es.mw.tum.de

Stephan Gleis, Spliethoff Hartmut

Lehrstuhl Energiesysteme, Technische Universität München (TUM), Boltzsmannstrasse 15, 85748 Garching, Germany

Patrik Yrjas, Mikko Hupa

Combustion and Materials Chemistry, Åbo Akademi Process Chemistry Centre, Biskopsgatan 8, FI-20500 Åbo, Finland

1

Corresponding author.

J. Eng. Gas Turbines Power 131(1), 011801 (Oct 14, 2008) (8 pages) doi:10.1115/1.2969090 History: Received April 09, 2008; Revised April 15, 2008; Published October 14, 2008

## Abstract

Naturally occurring limestone and dolomite samples, originating from different geographical locations, were tested as potential sorbents for carbonation/calcination based $CO2$ capture from combustion flue gases. Samples have been studied in a thermogravimetric analyzer under simulated flue gas conditions at three calcination temperatures, viz., $750°C$, $875°C$, and $930°C$ for four carbonation calcination reaction (CCR) cycles. The dolomite sample exhibited the highest rate of carbonation than the tested limestones. At the third cycle, its $CO2$ capture capacity per kilogram of the sample was nearly equal to that of Gotland, the highest reacting limestone tested. At the fourth cycle it surpassed Gotland, despite the fact that the $CaCO3$ content of the Sibbo dolomite was only 2/3 of that of the Gotland. Decay coefficients were calculated by a curve fitting exercise and its value is lowest for the Sibbo dolomite. That means, most probably its capture capacity per kilogram of the sample would remain higher, well beyond the fourth cycle. There was a strong correlation between the calcination temperature, the specific surface area of the calcined samples, and the degree of carbonation. It was observed that the higher the calcination temperature, the lower the sorbent reactivity. The Brunauer–Emmett–Teller measurements and scanning electron microscope images provided quantitative and qualitative evidences to prove this. For a given limestone/dolomite sample, sorbent’s $CO2$ capture capacity depended on the number of CCR cycles and the calcination temperature. In a CCR loop, if the sorbent is utilized only for a certain small number of cycles $(<20)$, the $CO2$ capture capacity could be increased by lowering the calcination temperature. According to the equilibrium thermodynamics, the $CO2$ partial pressure in the calciner should be lowered to lower the calcination temperature. This can be achieved by additional steam supply into the calciner. Steam could then be condensed in an external condenser to single out the $CO2$ stream from the exit gas mixture of the calciner. A calciner design based on this concept is illustrated.

<>

## Figures

Figure 1

CO2 capture based on CCR integrated into a combustion process

Figure 2

Equilibrium partial pressure of CO2 plotted against the temperature as obtained by thermodynamic calculations

Figure 3

TGA instrument used for the experiments with magnified sample holder

Figure 4

Decomposition curves of the samples obtained by DTA coupled with TGA

Figure 5

Gotland limestone conversion of CaO (mol %) to CaCO3 is plotted as a function of the number of cycles for a range of calcination temperatures from 750°C to 930°C

Figure 6

Gotland limestone calcination (CaCO3 to CaO conversion) rate during the first cycle for a range of calcination temperatures from 750°C to 930°C

Figure 7

Conversion of CaO (mol %) into CaCO3 plotted as a function of the number of cycles for all four samples; the calcination temperature was 875°C

Figure 8

CO2 captured in grams per kilogram of parent samples plotted against the number of cycles; the calcination temperature was 875°C

Figure 9

Conversion of CaO (mol %) to CaCO3 rates plotted during the first cycle for all four samples calcined at 875°C

Figure 10

Measured and predicted CaO (mol %) to CaCO3 conversions by Eq. 7 for two different calcination temperatures of 750°C and 930°C; ±10% margins were marked

Figure 11

Gotland and Sibbo dolomite—BET surface areas of CaO and respective CaO (mol %) conversion curves. The hollow signs belong to the secondary Y-axis.

Figure 12

SEM image of Gotland—calcined at 750°C and magnified to 10,000

Figure 13

SEM image of Gotland—calcined at 875°C and magnified to 10,000

Figure 14

SEM image of Sibbo dolomite—calcined at 750°C and magnified to 10,000

Figure 15

SEM image of Sibbo dolomite—calcined at 875°C and magnified to 10,000

Figure 16

Sketch of a calciner operated with steam supply

## Discussions

Some tools below are only available to our subscribers or users with an online account.

### Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related Proceedings Articles
Related eBook Content
Topic Collections