Calcium Carbonate Looping:
CO2 capture by using limestone in the cement industry
J. Hilz, M. Haaf, M. Helbig, J. Ströhle, B. Epple, Institute for Energy Systems and Technology (EST), TU Darmstadt, Darmstadt, Germany
The cement industry is currently responsible for approximately 5 % of the global greenhouse gas emissions. In the cement production process, CO2 is mainly released from the raw meal calcination and the fossil fuel combustion. The aim for reduction of specific CO2 emissions can be realized by application of Carbon Capture and Storage (CCS) technologies. Thereby, Calcium Carbonate Looping (CaL) is a promising and competitive CCS technology for capturing CO2 from flue gases. The CaL technology uses CaO to absorb CO2 from flue gases in a first reactor (carbonator) with an exothermic carbonation reaction, where CaCO3 is formed. The CaCO3 is transferred to a second reactor (calciner), where the CO2 is released from the sorbent in an endothermic calcination reaction. The process is realized in an interconnected dual fluidized bed system. Comparing the CaL technology to other CCS technologies applicable to the cement industry, various synergies between the cement production process and the CaL technology are apparent. Solid management of CaO-bearing material is very similar in both processes. The future perspective using purge CaL material for cement production is promising as the purge material is chemically compatible as cement production material. The present paper summarizes the demonstration of the CaL process in an industrially relevant environment. Long-term operation in a semi-industrial scale 1 MWth pilot plant was successfully carried out setting the basis for industrial application of the technology. The data from pilot testing were used to validate CaL process models. Thus, a detailed thermodynamic evaluation of the CaL integration scenario to a cement plant was carried out.
Summary CEMENT INTERNATIONAL 01/2017 pp 52-63
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