Chemical Compositional Changes in Coal Fly Ash through an Integrated Amine-Based Post-combustion SO₂ and CO₂ Capture Process

ABSTRACT

Combustion of coal in air leads to a gaseous product stream (flue gas) that mainly contains nitrogen (N₂), carbon dioxide (CO₂), water vapor, and small quantities of many other gases such as sulphur oxides (SO₂ and SO₃) and nitrogen oxides (NO_x mainly, NO, and NO₂) as well as particulates (mainly coal fly ash (CFA)) at different concentrations depending upon the content of the coal and the quantity of air used for its combustion. The need to maintain reliable power while reducing greenhouse gas emissions has been driving governments and companies worldwide toward CO₂ capture and storage/utilization. One such initiative is SaskPower's Integrated Carbon Capture and Storage (CCS) project at its Boundary Dam Unit 3 (BD3), which is amine based and just passed 10 years of commercial operation. The listed impurities in coal flue gas, of which CFA is the current focus, can cause degradation of the amines and have many other adverse effects on the capture process. Indeed, current electrostatic precipitators or fabric filters are designed to remove most of the CFA (typically up to ~ 99.9% or 99.99%, respectively), yet accumulation of the relatively small unremoved fraction within the CCS process is documented as causing physical barriers to the operation. One aspect of the effect of CFA on the amine-based CO₂ capture system which is very poorly elucidated is its interactions with the gaseous acidic impurities in the flue gas and with added treatment chemicals as it traverses various sections of the process under different conditions such as pH and temperature, and how these can affect the overall performance of CCS systems. In this current paper we present the chemistry behind changes in the composition of CFA as it travels through the flue gas pretreatments and the integrated amine-based post-combustion SO₂ and CO₂ capture process at the BD3 CCS facility. Generally, through the various stages of treatment, CFA is modified in various ways including a) extensive depletion of water or acid leachable ions of metals like aluminium (Al), iron (Fe), magnesium (Mg), sodium (Na), and potassium (K) at the pre-scrubbing stage (pH ~2); b) co-deposition with CFA of sulphate and phosphate salts of Na, Fe, and barium (Ba) due to leaching of the respective ions from CFA (and from steel material corrosion in the case of Fe) at the flue gas cooling and the SO₂ absorption stages, at high enough levels to exceed their saturation point or solubility products; and c) silicon dioxide or silica (SiO₂) removal at certain sections within the CO₂ capture stage due to its leaching from CFA under some high pH and temperature conditions.

REFERENCES

• Giannaris, S., Janowczyk, D., Ruffini, J., Hill, K., Jacobs, B., Bruce, C., Feng, Y., Srisang, W., "SaskPower's Boundary Dam Unit 3 Carbon Capture Facility – The Journey to Achieving Reliability", Proc., 15th International Conference on Greenhouse Gas Control Technologies, GHGT-15, 2021 (Abu Dhabi, United Arab Emirates). International Energy Agency Greenhouse Gas R&D Programme, Cheltenham, United Kingdom.
• Thambimuthu, K., Soltanieh, M., Abanades, J. C., Allam, R., Bolland, O., Davison, J., Feron, P., Goede, F., Herrera, A., Iijima, M., Jansen, D., Leites, I., Mathieu, P., Rubin, E.,  Simbeck, D., Warmuzinski, K., Wilkinson, M., Williams, R., Jaschik, M., Lyngfelt, A.,  Span, R., Tanczyk, M., "Chapter 3: Capture of CO₂", Carbon Dioxide Capture and Storage (Eds.: B. Metz, O. Davidson, H. de Coninck, M. Loos, L. Meyer), 2005. Cambridge University Press, New York, NY, USA, 105.
• Iijima, M., Takashina, T., Iwasaki, S., Okino, S., Kishimoto, S., "Long-Term Demonstration of CO₂ Recovery from the Flue Gas of a Coal-Fired Power Station", Mitsubishi Heavy Industries Ltd Technical Reviews 2007, 44(2), 1.
• Chandan, P., Richburg, L., Bhatnagar, S., Remias, J. E., Liu, K., "Impact of Fly Ash on Monoethanolamine Degradation during CO₂ Capture", International Journal of Greenhouse Gas Control 2014, 25, 102.
• Schallert, B., Neuhaus, S., Satterley, C. J., "Do We Underestimate the Impact of Particles in Coal-Derived Flue Gas on Amine-Based CO₂ Capture Processes?", Energy Procedia 2013, 37, 817.
• Schallert, B., Neuhaus, S., Satterley, C. J., "Is Fly Ash Boosting Amine Losses in Carbon Capture from Coal?", Energy Procedia 2014, 63, 1944.
• Da Silva, E. F., Lepaumier, H., Grimstvedt, A., Vevelstad, S. J., Einbu, A., Vernstad, K., Svendsen, H. F., Zahlsen, K., "Understanding 2-Ethanolamine Degradation in Postcombustion CO₂ Capture", Industrial and Engineering Chemistry Research 2012, 51(41), 13329.
• Schallert, B., Leaching of Fly Ash Particulate Matter in MEA Solutions and Its Relevance to the CO₂ Capture Process with Flue Gas of Coal-Fired Power Plants, 2020. Ph.D. Thesis, University of Stuttgart, Baden-Wurttemberg, Germany.
• Schallert, B., Dux, D., Neuhaus, S., Satterley C. J., "Accumulation of Absorbed Fly Ash Particulate Matter and its Impact on the CC Process", Energy Procedia 2016, 86,150.
• Azzi, M., Day, S., French, D., Halliburton, B., Element, A., Farrell, O., Feron, P., Impact of Flue Gas Impurities on Amine-Based PCC Plants – Final Report, 2013. Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia.
• Endo, T., Kajiya, Y., Nagayasu, H., Iijima, M., Ohishi, T., Tanaka, H., Mitchell, R., "Current Status of MHI CO₂ Capture Plant Technology, Large Scale Demonstration Project and Road Map to Commercialization for Coal Fired Flue Gas Application", Energy Procedia 2011, 4, 1513.
• Nath, D., Campbell, C., Feng, Y., Bruce, C., Philip, F., Henni, A., Srisang, W., Jacobs, B., Giannaris, S., Janowczyk, D., "A Novel Methodology for Online Analysis of Amine Solution Degradation Caused by Fly Ash", Proc., 15th International Conference on Greenhouse Gas Control Technologies (GHGT-15), 2021 (Abu Dhabi, UAE). International Energy Agency (IEA) Greenhouse Gas R&D Programme, Cheltenham, UK.
• Clery, D. S., Mason, P. E., Barnes, D. C., Szuhánszki, J., Akram, M., Jones, J. M., Pourkashanian, M., Rayner, C. M., "The Effect of Biomass Ashes and Potassium Salts on MEA Degradation for BECCS", International Journal of Greenhouse Gas Control 2021, 108, 103305.
• Dumée, L. F., Scholes, C., Stevens, G., Kentish, S., "Purification of Aqueous Amine Solvents Used in Post Combustion CO₂ Capture: A Review”, International Journal of Greenhouse Gas Control 2012, 10, 443.
• Ratman, I., Kusworo, T. D., Ismail, A. F., "Foam Behaviour of an Aqueous Solution of Piperazine-N-Methyldiethanolamine (MDEA) Blend as a Function of the Type of Impurities and Concentrations", International Journal of Waste Resources 2011, 1(2), 8.
• Pauley, C. R., Hashemi, R., Caothien, S., "Analysis of Foaming Mechanisms in Amine Plants", Proc., American Institute of Chemical Engineer' Summer Meeting, 1988 (Denver, CO, USA). American Institute of Chemical Engineers, New York, NY, USA.
• Rakottyay, K., Kaszonyi, A., Vajíček, S., "Oxidation of Amines over Alumina Based Catalysts", Applied Catalysis A: General 2010, 378(1), 33.
• Schümperli, M. T., Hammond, C., Hermans, I., "Developments in the Aerobic Oxidation of Amines", ACS Catalysis 2012, 2(6), 1108.
• Armor, J. N., Catalytic Oxidation of Primary Amines to Oximes by Elemental Oxygen, 1985. United States Patent and Trademark Office, US 4504681 A.
• Lupu, C., Jackson, K. L., Bard, S., Barron, A. R., "Water, Acid, and Calcium Carbonate Pre-treatment of Fly Ash: The Effect on Setting of Cement-Fly Ash Mixtures", Industrial & Engineering Chemical Research 2007, 46(24), 8018.
• Li, L., Fan, M., Brown, R. C., Koziel, J. A., van Leeuwen, J. H., "Reduction of SO₂ in Flue Gas and Applications of Fly Ash: A Review", PowerPlant Chemistry 2008, 10(5), 291.
• Fly Ash Facts for Highway Engineers, 2003. American Coal Ash Association, Aurora, CO, USA.
  Available from https://highways.dot.gov/.
• Cheng, J., Zhou, J., Liu, J., Zhou, Z., Huang, Z., Cao, X., Zhao, X., Cen, K., "Sulfur Removal at High Temperature during Coal Combustion in Furnaces: A Review", Progress in Energy and Combustion Science 2003, 29(5), 381.
• Bhatt, A., Priyadarshini, S., Mohanakrishnan, A. A., Abri, A., Sattler, M., Techapaphawit, S., "Physical, Chemical, and Geotechnical Properties of Fly Ash: A Global Review", Case Studies in Construction Materials 2019, 11, e00263.
• Makinta, B., Mohammed, K., Ocholi, A., "Effect of Elevated Temperatures on the Durability and Strength Properties of Concrete with Ground Rice Husk Ash as a Partial Replacement to Cement: A Review", Arid Zone Journal of Engineering, Technology and Environment 2021, 17(2), 243.
• Shaw, D., "Cansolv CO₂ Capture: The Value of Integration", Energy Procedia 2009, 1(1), 237.
• Rahm, J. A., Davis, B. R., Process for the Preparation of Titanium Sulfate, 1987. Finnish Patent and Registration Office, FI71544C.
• Goff, G. S., Rochelle, G., "Oxidation Inhibitors for Copper and Iron Catalyzed Degradation of Monoethanolamine in CO₂ Capture Processes", Industrial & Engineering Chemistry Research 2006, 45(8), 2513.
• Chi, S., Rochelle, G. T., "Oxidative Degradation of Monoethanolamine", Industrial & Engineering Chemistry Research 2002, 41(17), 4178.
• Fredriksen, S. B., Jens, K.-J., "Oxidative Degradation of Aqueous Amine Solutions of MEA, AMP, MDEA, Pz: A Review", Energy Procedia 2013, 37, 1770.
• Vega, F, Sanna, A, Navarrete, B, Maroto-Valer, M. M., Cortés, V. J., "Degradation of Amine-based Solvents in CO₂ Capture Process by Chemical Absorption", Greenhouse Gases: Science and Technology 2014, 4(6), 707.
• Léonard, G., Voice, A., Toye, D., Heyen, G., "Influence of Dissolved Metals and Oxidative Degradation Inhibitors on the Oxidative and Thermal Degradation of Monoethanolamine in Postcombustion CO₂ Capture", Industrial & Engineering Chemistry Research 2014, 53(47), 18121.
• Rao, B., Dai, H., Gao, L., Xie, H., Gao, G., Peng, K., Zhang, M., He, F., Pan, Y., "Surprisingly Highly Reactive Silica that Dissolves rapidly in Dilute Alkali (NaOH) Solution Even at Ambient Temperatures (25°C)", Journal of Cleaner Production 2022, 341, 130779.
• Fertani-Gmati, M., Brahim, K., Khattech, I., Jemal, M., "Thermochemistry and Kinetics of Silica Dissolution in NaOH Solutions: Effect of the Alkali Concentration", Thermochimica Acta 2014, 594, 58.
• Febriana, E., Manurung, U. A. B, Prasetyo, A. B., Handayani, M., Muslih, E. Y., Nugroho, F., Sulistiyono, E., Firdiyono, F., "Dissolution of Quartz Sand in Sodium Hydroxide Solution for Producing Amorphous Precipitated Silica", IOP Conference Series: Materials Science and Engineering 2020, 858, 012047.
• Tanaka, M., Takahashi, K., "The Identification of Chemical Species of Silica in Sodium Hydroxide, Potassium Hydroxide and Sodium Chloride Solutions by FAB-MS", Analytical Sciences 1999, 15(12), 1241.
• Lichtner, P., Eikenberg, J., Propagation of a Hyperalkaline Plume into the Geological Barrier Surrounding a Radioactive Repository, 1994. National Cooperative for the Disposal of Radioactive Waste (Nagra), Wettingen, Switzerland, NAGRA NTB 93-16.
• Boon, J. A., Silica Dissolution from Oil Sands, 1979. Alberta Research Council, Edmonton, AB, Canada, ARC/AGS OFR 1985-09.
• Izquierdo, M., Querol, X., "Leaching Behaviour of Elements from Coal Combustion Fly Ash: An Overview", International Journal of Coal Geology 2012, 94, 54.