Demonstration of steady state CO2 capture in a 1.7MWth calcium looping pilot

Abstract

Calcium looping, CaL, is rapidly developing as a postcombustion CO 2 capture technology because its similarity to existing power plants using circulating fluidized bed combustors, CFBC. In this work we present experimental results from a pilot built to demonstrate the concept at the MW th scale. The pilot plant treats 1/150 of the flue gases of an existing CFBC power plant ("la Pereda") and it has been operated in steady state for hundreds of hours of accumulated experimental time. The pilot includes two 15 m height interconnected circulating fluidized bed reactors: a CO 2 absorber (or carbonator of CaO) and a continuous CaCO 3 calciner operated as an oxy-fuel CFBC. Operating conditions in the reactors are resembling those expected in large CaL CO 2 capture systems in terms of reactor temperatures, gas velocities, solid compositions and circulation rates and reaction atmospheres. The evolution of CO 2 capture efficiencies, solid properties (CO 2 carrying capacity and CaO conversion to CaCO 3 and CaSO 4) have been studied as a function of key operating conditions. It is demonstrated that CO 2 capture efficiencies over 90% are feasible with a supply of active CaO slightly over the molar flow of CO 2 entering the carbonator. Closure of carbon and sulphur balances has been satisfactory during steady state periods. A basic reactor model developed from smaller test facilities seems to provide a reasonable interpretation of the observed trends. This should facilitate the further scale up of this new technology.

Effect of dolomite decomposition under CO2 on its multicycle CO2 capture behaviour under calcium looping conditions

“…In this way, a high CO 2 concentration stream can be retrieved from the calciner for compression and storage or other uses. Thus, the sorbent undergoes repeated carbonation/calcinations (carb/calc) cycles while it is circulated between the calciner and the carbonator [1, [7][8][9][10].…”

“…Firstly, the high temperature required to achieve a complete regeneration of the sorbent in short residence times since calcination has to be carried out under the high CO 2 partial pressure calciner environment [11][12][13][14]. Such high temperatures would be attained by oxy-combustion in order to avoid CO 2 dilution, which entails a marked energy penalty to the process due to fuel consumption and additional CO 2 production [9,10,[14][15][16][17][18]. The second inconvenient is the progressive deactivation of the sorbent along the successive carb/calc cycles that makes necessary to periodically introduce a fresh limestone makeup into the calciner.…”

“…The second inconvenient is the progressive deactivation of the sorbent along the successive carb/calc cycles that makes necessary to periodically introduce a fresh limestone makeup into the calciner. CaO deactivation may occur due to the screening effect of external agents such as ash or SO 2 produced during oxycombustion, which leads to the irreversible sulphation of the CaO particles [9,13,19,20]. Yet, deactivation is mostly caused by the drastic loss of surface area of the CaO grains when calcination takes place under high CO 2 partial pressure and high temperatures, which enhances aggregation and subsequent sintering of the nascent CaO nanocrystals during the CaCO 3 /CaO transformation [21].…”

Modelling of the kinetics of sulphation of CaO particles under CaL reactor conditions

“…La Pereda (Spain) which produces 1.7 MWth and is the largest CaL for CO 2 capture installed so far [8,9]. Other pilots that have achieved promising results are the 1 MWth pilot plant in Darmstadt (Germany) [10], the 0.3 MWth pilot in La Robla [11], the 0.2 MWth pilot at Stuttgart University (Germany) [12] and the 1.9 MWth pilot that is being constructed in Taiwan [13], apart from smaller projects that have also reported positive results [14][15][16].…”

Scale-Up Effects of CO2 Capture by Methyldiethanolamine (MDEA) Solutions in Terms of Loading Capacity

“…As stated by Arias [9], the main challenge for scaling-up is to progress from the experimental demonstration of the concept at an increasing scale and under realistic conditions, simultaneously validating the expected benefits and overcoming the obstacles that may appear in the path towards large-scale demonstration. In particular, the actual need to perform scale-up for CO 2 absorption plants is considered critical [2], as the existing ones are not enough to deal with the current huge amount of CO 2 emissions to the atmosphere.…”