To deal with the Greenhouse Gases (GHG) emission increase, CO2 capture and storage is one of the possible way to lower emissions due to fossil fuel use for electricity production. Different technologies for CO2 capture are currently under development: membrane separation, physical/chemical absorption, adsorption. If the separation is easier in the pre-combustion case as the CO2 molar fraction is high (typically about 30%), post combustion capture is the main way to lower the emission of existing power plants and future power plants where CO2 is produced during the combustion. The major difficulty of post combustion capture is to produce a highly concentrated CO2 stream matching the purity requirement for transportation while CO2 is diluted in the flue gas. Its concentration ranges between 4% for Natural Gas Combined Cycle and 14% for pulverised coal for example. Of course, the energy consumption has to be low while keeping high CO2 recovery. Chemical absorption is today reference process with an energy cost ranging from 1.2 to 4 MJ/kgCO2 depending on the amine type and process configuration. Adsorption processes were first not really considered as competitive for CO2 capture when compared to absorption. Nevertheless, recent work has proven the interest of PSA/VSA processes for this application showing low energy consumptions. However the consumed energy is of mechanical work type whereas heat is directly used in chemical absorption. For these reasons, we have chosen to evaluate the potential of post combustion capture by Temperature Swing Adsorption (TSA). Contrarily to PSA/VSA, TSA can be directly heat driven. However, the main drawbacks of TSA are its low productivity, which results in large adsorbent, amount and adsorbate dilution during desorption because of the regeneration by hot gas. To avoid these drawbacks, an indirect TSA process developed in our laboratory is used. The originality of this process comes from the indirect heating during the regeneration step of the process using an internal heat exchanger. Thanks to this heat exchanger, the adsorption step is cooled as well.

In this paper, a numerical parametric study of our adsorption process is presented. The model describes mass, energy and momentum balance coupled with equations for equilibrium, equation of state and thermodynamic or transport properties. The following input parameters were used : feed gas CO2 composition, temperature and flowrate, desorption temperature, and purge flowrate. Furthermore, a pre-cooling step influence was addressed as well. To qualify the performances, CO2 capture rate, purity, productivity and specific energy consumption were used. If very high CO2 purities can be achieved (>95%) a trade-off has to be found with productivity. Concerning energy consumption, the net amount is considered but the temperature level of the requested heat source is discussed as this aspect will be of major importance for process integration.