CO2 Capture Technologies for Cement Industry

Abstract

The effect of the increasing concentration of CO2 in the atmosphere on climate change is a major driving force for the development of advanced energy cycles incorporating CO2 management options. Growing interest in the technical and economic feasibility of CO2 capture from large coal-based power plants has led to increased efforts worldwide to develop new concepts for greater CO2 reductions in the future. Greenhouse gas emissions, especially CO2, have to be reduced by 50–80% by 2050, according to the IPCC [1]. The type of fuel used in cement manufacture directly impacts on CO2 emissions, with coal accounting for around 60–70% of CO2 emissions from cement installations. Therefore, the large amount of carbon dioxide emitted during cement manufacturing process - 5% of the total emissions of CO2 from stationary sources worldwide - is a cause of great concern and has to be tack led in order to comply with current legislation. Several technologies are available and have been proposed for the separation of CO2 from the flue gases from new and existing plants with retrofit capture units. Few studies have been undertaken on CO2 capture in cement plants to assess the suitable technologies, with oxy-combustion and amine scrubbing as the possible options (pre-combustion capture not being viable). This paper summarises the different CO2 capture technologies suitable for cement industry and assesses the potential of the calcium looping cycle [2,3] as a new route for CO2 capture in the cement industry. The potential advantage of this system is the very low efficiency penalty expected (<6%) compared with other capture technologies as the heat required for calcination is balanced by heat released during the carbonation (CO2 capture) step and can be utilized efficiently at high temperature in the plant’s steam cycle. Since limestone is already used for cement manufacture, and because it is a cheap material with good geographical distribution, it allows the use of local limestone resources with minimal limestone-related infrastructure investment. Another envisaged benefit of this new technology is that the lime purged from the cycle could be us ed as a raw material for the production of cement clinker. Therefore, the calcium looping cycle can potentially have an important impact in reducing CO2 emissions from the cement industry, and may also be applicable in other sectors.