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Limestone powder CO2 scrubberartificial limestone weathering for reduction of flue gas CO2 emissions
Abstract
A process which uses a limestone powder suspension to convert CO 2 to water-soluble hydrogen carbonate bicarbonate has been developed. For this purpose, prescrubbed CO2-containing flue gases, such as occur in flue gas desulphurisation, are submitted to wet scrubbing using a suspension of limestone powder. Calcium hydrogen carbonate which also occurs as a natural constituent of limnic and oceanic waters, and thus fixes CO 2 in stable equilibrium, is formed, analogously to the natural weathering of limestone, rather than calcium sulphate. The results obtained confirm the process's suitability in principle for the removal of CO2 from flue gases and for the stable transportation of the carbonate hardness formed in the aqueous fluid. Only the test apparatus with an open gas and scrubbing-fluid circuit was used in the practical tests. CO2 concentration during these tests remained very largely constant, at around 11.8% vol., with only slight fluctuations of some ± 0.2%vol.
... They found that better rate of reactions can be achieved by using smaller grain size and increasing in flow rate of CO2 during AWL process. A similar study by Haas et al. [10] employed lab-scale apparatus to investigate the effect of temperature, ion concentration, and pressure of CO2 on AWL. Subsequently, the pilot scale was developed to verify the repeatability of the lab scale's tests as well as to investigate the process' feasibility at the municipal sewage treatment plant in Bad Orb, Germany. ...
... The presence of harmful substances in the product waters was also investigated. This study obtained higher CO2 removal efficiency compared to Haas et al. [10] but lower than that achieved in their prior work on the lab-scale reactors. Subsequently, higher TA achieved through circulating product water compared to Chou et al. [11] and Rau [1] but not at equilibrium due to an unexpected power plant shut down. ...
The present work explores accelerated weathering of limestone (AWL) as an option to combat the climate change problem posed by the still growing carbon footprint. AWL is a promising low-technology solution that sequesters CO2 through the dissolution of calcium carbonate (CaCO3) in water to form calcium bicarbonate. One aspect of the feasibility of its application is whether the newly formed bicarbonate will remain in solution for the long term. This paper examines the carbonate equilibria for various water bodies by combining Bjerrum plots with the calcite saturation value, omega.
The hydrochemistry software, aqion, was used to simulate a range of water compositions with different salinities at various conditions. The study compares saturation states of rainwater, limestone quarry water, seawater, and reverse osmosis concentrate, with their respective dissolved inorganic carbon (DIC) concentrations, across the full range of pH values. The areas of stability and instability can be observed from the generated plots in order to be able to design effective AWL processes. A key issue for successful implementation of AWL is operating within the CaCO3 saturation limit and ensuring dissolved material does not subsequently reprecipitate.
... They found that better rate of reactions can be achieved by using smaller grain size and increasing in flow rate of CO2 during AWL process. A similar study by Haas et al. [10] employed lab-scale apparatus to investigate the effect of temperature, ion concentration, and pressure of CO2 on AWL. Subsequently, the pilot scale was developed to verify the repeatability of the lab scale's tests as well as to investigate the process' feasibility at the municipal sewage treatment plant in Bad Orb, Germany. ...
... The presence of harmful substances in the product waters was also investigated. This study obtained higher CO2 removal efficiency compared to Haas et al. [10] but lower than that achieved in their prior work on the lab-scale reactors. Subsequently, higher TA achieved through circulating product water compared to Chou et al. [11] and Rau [1] but not at equilibrium due to an unexpected power plant shut down. ...
The present work explores accelerated weathering of limestone (AWL) as an option to combat the climate change problem posed by the still growing carbon footprint. AWL is a promising low-technology solution that sequesters CO2 through the dissolution of calcium carbonate (CaCO3) in water to form calcium bicarbonate. One aspect of the feasibility of its application is whether the newly formed bicarbonate will remain in solution for the long term. This paper examines the carbonate equilibria for various water bodies by combining Bjerrum plots with the calcite saturation value, omega.
The hydrochemistry software, aqion, was used to simulate a range of water compositions with different salinities at various conditions. The study compares saturation states of rainwater, limestone quarry water, seawater, and reverse osmosis concentrate, with their respective dissolved inorganic carbon (DIC) concentrations, across the full range of pH values. The areas of stability and instability can be observed from the generated plots in order to be able to design effective AWL processes. A key issue for successful implementation of AWL is operating within the CaCO3 saturation limit and ensuring dissolved material does not subsequently reprecipitate.
... Die abschließende verfahrenstechnische Bewertung des Carbonat-CO 2 -Waschverfahrens als Alternative zum CCS-Konzept mit einer Kosten/Nutzen-Abschätzung auf Basis der ermittelten Untersuchungsergebnisse ergab trotz höherer Investitionskosten günstigere Gesamtkosten im Vergleich zum aminbasierten Waschverfahren des CCS-Konzeptes [13,31,32]. ...
Various methods have been proposed for mitigating release of anthropogenic CO2 to the atmosphere, including deep-sea injection of CO2 captured from fossil-fuel fired power plants. Here, we use a schematic model of ocean chemistry and transport to analyze the geochemical consequences of a new method for separating carbon dioxide from a waste gas stream and sequestering it in the ocean. This method involves reacting CO2-rich power-plant gases with seawater to produce a carbonic acid solution which in turn is reacted on site with carbonate mineral (e.g., limestone) to form Ca2+ and bicarbonate in solution, which can then be released and diluted in the ocean. Such a process is similar to carbonate weathering and dissolution which would have otherwise occurred naturally, but over many millennia. Relative to atmospheric release or direct ocean CO2 injection, this method would greatly expand the capacity of the ocean to store anthropogenic carbon while minimizing environmental impacts of this carbon on ocean biota. This carbonate-dissolution technique may be more cost-effective and less environmentally harmful, and than previously proposed CO2 capture and sequestration techniques.
The use and impacts of accelerated weathering of limestone (AWL; reaction: CO2+H2O+CaCO3→Ca2++2(HCO3−) is explored as a CO2 capture and sequestration method. It is shown that significant limestone resources are relatively close to a majority of CO2-emitting power plants along the coastal US, a favored siting location for AWL. Waste fines, representing more than 20% of current US crushed limestone production (>109 tonnes/yr), could provide an inexpensive or free source of AWL carbonate. With limestone transportation then as the dominant cost variable, CO2 mitigation costs of 4/tonne appear to be possible in certain locations. Perhaps 10–20% of US point–source CO2 emissions could be mitigated in this fashion. It is experimentally shown that CO2 sequestration rates of 10−6 to 10−5 moles/sec per m2 of limestone surface area are achievable, with reaction densities on the order of 10−2 tonnes CO2 m−3day−1, highly dependent on limestone particle size, solution turbulence and flow, and CO2 concentration. Modeling shows that AWL would allow carbon storage in the ocean with significantly reduced impacts to seawater pH relative to direct CO2 disposal into the atmosphere or sea. The addition of AWL-derived alkalinity to the ocean may itself be beneficial for marine biota.