Process for Capturing CO₂ Arising from the Calcination of the CaCO₃ Used in Cement Manufacture

Abstract

This paper outlines a new CaCO3 calcination method for producing a stream of CO2 (suitable for permanent geological storage after purification and compression). The process is based on the use of very hot CaO particles (T >1000 degrees C) to transfer heat from a circulating fluidized bed combustor (CFBC) to a calciner (fluidized with CO2 and/or steam). Since the fluidized bed combustor and calciner have separate atmospheres, the CO2 resulting from the decomposition of CaCO3 can be captured, while the CO2 generated in the combustion of the fuel in air is emitted to the atmosphere. We demonstrate that with this system it is possible to reduce the CO2 emissions of a cement plant by around 60%. Furthermore, since the key pieces of equipment are similar to the commercial CFBCs used in power generation plants, it is possible to establish the additional investment required for the system and to estimate the cost per ton of CO2 avoided for this process to be about 19 $/tCO2 avoided.

Synthesis of CaO-SiO<sub>2</sub> Compounds Using Materials Extracted from Industrial Wastes

“…Chalk consists of calcium carbonate, and used chalk usually becomes waste. Also, the decomposition temperature of CaCO 3 is lower than that of gypsum [20]. To synthesize calcium silicate, both an alginate impression gel and chalk powder were prepared.…”

CO2 Carrying Capacities of Cement Raw Meals in Calcium Looping Systems

“…19,22,24,33,34 The theoretical synergy of CaL with cement manufacture has been investigated in previous simulation works and lab scale studies. 11,[13][14][15][17][18][19][21][22][23][24][25][26][27][28]30 However, hardly any experimental information on the performance of the raw meals as CO 2 sorbents in CaL systems is available in the literature. Only Pathi et al 21 have carried out cyclic experiments in a thermogravimetric analyzer (TGA) to study the effect of SiO 2 , Al 2 O 3 , and Fe 2 O 3 on the CO 2 carrying capacity of the CaO present in raw meals.…”

CCS from industrial sources

“…There are two major sources of CO 2 in the cement production process-from the calcination of limestone (CaCO 3 ) to form CaO (around 60% of the total emissions, excluding the fuel used to effect the calcination [17]), the major constituent of ordinary Portland cement, and from the fuel used to raise the temperature in the cement kiln and to effect the calcination (approximately 40% of the total emissions) to effect the chemical reactions necessary to produce cement [18]. These figures agree with recent ones presented by Cemex [19], the world's third largest cement manufacturer.…”

“…The cost for decarbonisation of cement manufacture has been estimated for calcium looping as ∼$20/tCO 2 [18], and for general post-combustion capture using this process of $15-20/tCO 2 [26]. Kuramochi et al [23] quote costs (per tCO 2 ) for a variety of short/medium term processes of between $35 for Ca looping precalcination (based on [18]) to $47-67 for advanced solvents (the lower figure is for steam import from a power station, the higher figure for boiler steam import), around $56 for oxyfuel operation and $85-117 for MEA-based scrubbing (again, the lower figure is for power station steam and the higher for boiler steam).…”

“…Kuramochi et al [23] quote costs (per tCO 2 ) for a variety of short/medium term processes of between $35 for Ca looping precalcination (based on [18]) to $47-67 for advanced solvents (the lower figure is for steam import from a power station, the higher figure for boiler steam import), around $56 for oxyfuel operation and $85-117 for MEA-based scrubbing (again, the lower figure is for power station steam and the higher for boiler steam). The IEA GHG programme [33] has assessed the costs of an oxyfired cement kiln in the UK, and estimated a cost of $54 for decarbonisation of the calciner only, or $29 for an Asian developing country.…”