Design And Development of A Carbonator For Carbon Dioxide Capture : Current School News

Design And Development of A Carbonator For Carbon Dioxide Capture Using Locally Produced Lime

 – Design And Development of A Carbonator For Carbon Dioxide Capture Using Locally Produced Lime – 

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ABSTRACT

The work seeks to address environmental issue through the design and development of a carbonator for CO2 capture.

A fixed bed carbonator with height 1.7 m and diameter0.9 m for CO2 capture was successfully designed and fabricated at a flow rate 7.9g/hr of carbon dioxide using 2kV household electric generator as a source of flue gas.

The fluegas was analyzed using NHA-506EN NANHUA Instrument gas analyzer and the average composition of the flue gas after allowing the generator to ran for 30min was found to be 7.78% CO, 2.50% CO2, 46ppm NOx, and 392ppm HC.

The material of construction used was mild steel and the fabrication was based on the specifications obtained from Aspes Plus version 11.1 software.

Hydrated lime Ca(OH)2 powder was made into pellets of different sizes: 0.8, 1.2, 1.5 and 2cm and packed differently at a height of 0.4m in the carbonator.

Flue gas at 150oC was passed through the bed of hydrated lime at 1atm. The average readings obtained from the outlet of the carbonator(top) were found to be 7.71%CO, 0.06% CO2, 46ppm NOx and 390ppm HC.

These results showed that there was decrease in carbon dioxide concentration as time pass by. For the 0.8cm pellet size and packing height of 0.4 m, there was 97.6% carbon dioxide capture which compares favorably with literature values.

The product (used lime) was taken for chemical analysis: XRF analysis gave 56.46%CaO, 1.52% SiO2, 3.44%Fe2O3; X-ray diffraction (XRD) showed that the used lime is crystalline and scanningelectron microscopy (SEM) presented irregular, heterogeneous and coarse particles.

TABLE OF CONTENTS

Title Page ………………………………………………………………………….. i
Declaration ………………………………………………………………………… ii
Certification ……………………………………………………………………… iii
Dedication ………………………………………………………………………… iv
Acknowledgement ……………………………………………………………….. v
Abstract ………………………………………………………………………… vii
Table of Contents ………………………………………………………………… viii
List of Figures.………………………………………………………………..……..xi
List of Tables ………………………………………………………………………..xiii
List of Plates…..……………………………………………………………………. xiv
List of Appendices ……………………………………………………………….. xv
List of Abbreviations……………………………………………………………………. xvi
INTRODUCTION
1.1 Preamble…………………………………………………………..……….….1
1.2 Problem Statement……………..……………………………………………2
1.3 Research Justification…………………………………………………………2
1.4 Aimand Objectives……………………………………………………… 3
1.4.1 Research aim………………………………3
1.4.2 Research objectives…………………………3
1.5 Scope of Research ………………………………………………………… 3
1.0 LITERATURE REVIEW
2.1 Global Climate Change…………………………………………………… 4
2.2 Overview of CO2 Capture Technologies………………..…………………….11
2.2.1 Post-combustion processes…………………………………………………………………. 11
2.2.2 Pre-combustion processes……………………………………………………………………18
2.2.3 Oxy-combustion systems…………………………………………………………………….21
2.3 Mineral Carbonation Mechanism and Processes………..………………22
2.3.1 Carbonation mechanism…………………………………………………….22
2.3.2 Calcium and magnesium (and iron) sources for mineral carbonation..……. 22
2.3.3 Carbonation processes……………………………………………………….25
2.4 Process Selection……………………………………………………………………………… 32
2.4.1 Fluidized bed reactor…………………………………………………………………………..33
2.4.2 Fixed bed reactor………………………………………………………………………………..33
2.5 Review of Related Studies………………………………………………………………….35
3.0 MATERIALS AND METHODS
3.1 Materials and equipment…………………………………………………………………. 36
3.2 Methodology……………………………………………………………………………………. 37
3.2.1 Flue gas analysis………………………………………………………………………………….37
3.2.2 Carbonator design using Aspen Plus software…………………………………………39
3.2.3 Material selection ………………………………………………………………………………41
3.2.4 Construction of carbonator ………………………………………………………………….42
3.2.5 Pelletization of hydrated lime…………………………………………………………….42
3.2.6 Test running of carbonator…………………………………………………………………..42
4.0 RESULTS AND DISCUSSION
4.1 Chemical Composition Analysis for Hydrated Lime…………..………..45
4.2 XRD Analysis for Hydrated Lime……………………………………………………..45
4.3 SEM Analysis for Hydrated Lime……………………….…………………49
4.4 Pelletization of Hydrated Lime………………………………………………………….52
4.5 Flue Gas Analysis……………………………………………………………………………..52
4.5.1 Working drawing………………………………………………………………………………..53
4.5.2 Construction ……………………………………………………………………………………..56
5.0 CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusions………………………………………………………………………………………62
5.2 Recommendations…………………………………………………………………………….62
REFERENCES……………………………………………………………………………………………63
APPENDICES ……………………………………………………………………..68

INTRODUCTION

Carbon dioxide (CO2) is a naturally occurring gas which plants use to live and grow. Over millions of years, plants and algae have been buried to produce oil and natural gas deposits, effectively ‗locking away‘ the CO2 they were using.

When fossil fuels are burned to produce electricity, the carbon within them is released back into the carbon cycle as CO2. This is now being emitted at such a rapid rate that the Earth‘s natural carbon cycle cannot accommodate.

Rising concentration of CO2 in the atmosphere is causing climate change; this involves global warming, increases in extreme weather events, ocean acidification and sea level rise.

Reducing the rate of CO2 emissions is consequently, a priority (Research Council UK, 2008).Fossil fuels, namely coal, natural gas, and oil, are currently the dominant sources of energy used for electricity generation worldwide.

Nearly 70% of the world‘s electricity is derived from a fossil fuel source with coal accounting for 41% of the world‘s electricity generation (IEA, 2010).

While coal utilization comprises a significant fraction of total electricity generation, it is also responsible for 43% of the world‘s carbon dioxide emissions (International Energy Agency, 2010).

With increasing concern over carbon dioxide emissions, current efforts are focused on processes that can economically and efficiently reduce carbon dioxide emissions to the atmosphere.

REFERENCES

Agnello, V.M. (2003). A review of the dolomite and limestone industry in SouthAfrica.Department of Minerals and Energy, Mineral Economics, SouthAfrica.Pages 2-10.Costa, G.; Baciocchi, R.; Polettini, A.; Pomi, R.; Hills, C.D.; Carey, P.J. (2007).

Currentstatus and perspectives of accelerated carbonation processes on municipalwaste combustion residue.Environ. Monit. Assess, 135, 55-75.

Crowley T.J. (2000).Causes of climate change over the past 1000 years.Science289:270–77. DOI: 10.1126/science.289.5477.270Dunsmore, H. E. (1992).

A geological perspective on global warming and thepossibility of carbon dioxide removal as calcium carbonate mineral. EnergyConversion and Management.Volume 33.Pages 565–572.DOI: 10.1016/0196-8904(92)90057-4Eloneva, S. (2004).

Mineral Carbonate Process Modeling and Carbonate ProductStability. Helsinki University of Technology: Greater Helsinki, Finland.Retrieved on 13 December, 2014 from www.oalib.com/references/8691093Fernández-Bertos, M.; Simons, S.J.R.; Hills, C.D.; Carey, P.J. (2004).

A review ofaccelerated carbonation technology in the treatment of cement-based materialsand sequestration of CO2.J. Hazar. Mater. 112. Pages 193-205.Fogler P. (2010).

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