Carbon dioxide capture using solid sorbents in a fluidized bed with reduced pressure regeneration in a downer

Abstract

The most common technology for postcombustion CO 2 capture for existing power plants is the amine solvent scrubber. The energy consumption for capturing CO 2 from flue gases using amine solvent technology is 15 to 30% of the power plant electricity production. Hence, there is a need to develop more efficient methods of removing CO 2 . Here, we show a novel design, obtained using multiphase CFD, and of a fluidized-bed reduced pressure regenerator, coupled with a fluidized-bed sorber, which has the potential to reduce the energy consumption. The undesirable core-annular flow regime in the riser-sorber is eliminated using multiple jet inlets and large particles leading to a shorter height. Up to 88% of the heat liberated in the riser-sorber is recovered in the downer-regenerator.

CO2 capture in a multistage CFB: Part I: Number of stages

“…When the bicarbonate reaches its decomposition pressure, the capture of CO 2 will stop . Hence, to adsorb the lower concentrations of CO 2 , the temperature of the sorbent must be lower.…”

“…There are several kinds of reactor to remove CO 2 from flue gases using alkali metal group I carbonate sorbents such as bubbling fluidized beds used at RTI, batch turbulent fluidized beds used in Thailand, circulating fluidized beds used in Korea, and moving beds . There are also a couple ways to regenerate the sorbents which are the application of heat and depressurization treatments . However, reducing the pressure requires additional electrical energy for a vacuum compressor besides the energy needed for a compressor to circulate the sorbent.…”

“…An alternative method is to utilize heat recovered from sorption reaction which considered to be one third of the heat of combustion together with the waste heat from the power plant. Kongkitisupchai and Gidaspow have also shown that one sorption stage is insufficient to remove 90% of CO 2 in flue gas due to equilibrium limitations . Park et al have patented the idea of using multistage CFBs for CO 2 capture process…”

Carbon Dioxide Capture from Flue Gas Using a Potassium-Based Sorbent in a Circulating-Turbulent Fluidized Bed

“…The characteristic of this velocity can be defined as the minimum gas velocity which requires to carry over a significant number of particles discharged from the riser. Various approaches used to investigate transport velocity of solid particles in the fluidized bed such as flooding point velocity determination [34,35], pressure drop calculating as a function of solids circulation rate and superficial gas velocities at the bottom of the column [3] and the emptying-times measurement technique of a fast fluidization column [36,37]. Among these approaches, the emptying-times is the most interesting technique because this method is simple and convenient.…”

“…Solid sorbents can overcome some of the limitations of the more conventional liquid aminebased absorption. Solid support materials loaded with active alkali-metal components such as Na-and Kbased have become a highly efficient method for capturing CO2 due to their high CO2 capture capacity, low cost and low energy requirement for capturing and releasing the CO2 [2][3][4][5][6]. The mechanism of CO2 capture for these porous materials such as activated carbon, TiO2, MgO, zeolite and activated alumina adsorbents [7,8] can be described in Eq.…”