Kinetic Model for Parallel Reactions of CaSO₄ with CO in Chemical-Looping Combustion

Abstract

Chemical-looping Combustion (CLC) has been proposed as an energy-efficient combustion method for in situ capture of CO2. Kinetic model for parallel reactions of the CaSO4 oxygen carrier with CO in a CLC process is explored in this paper. Tests on an isothermal reaction were carried out in a Thermogravimetric Analyzer coupled with Fourier Transform Infrared spectrum (TGA-FTIR), and the instantaneous evolutions of SO2 and COS were monitored by the FTIR quantitative analysis. The reaction temperature was varied between 850 and 1050 °C, while 5-28% CO concentrations were utilized. The experiments showed that the reduction of CaSO4 by CO was a complex process, with the products of either sole CaS or both CaS and CaO depending on the reaction temperature as well as the concentration of CO reactant. The parallel reactions of CaSO4 with CO were investigated in terms of the selectivity based on the nucleation and growth model under isothermal conditions. According to the fitting results, the nucleation and growth model fit well the conversion−time data, and some of the kinetic parameters were obtained.

Use of natural ores as oxygen carriers in chemical looping combustion: A review

“…The process was recently reviewed by Abad et al (2017). The reduction kinetics of CaSO 4 with CO in a differential fixed bed is studied by Zheng et al (2011) and Xiao et al (2010b). Song et al (2009) investigated a CaSO 4 oxygen carrier by thermodynamic analysis and thermogravimetric analysis.…”

Review: Circulation of Inorganic Elements in Combustion of Alternative Fuels in Cement Plants

“…The fundamentals of the reductive decomposition of CaSO 4 of mainly CO have been studied over a wide range of conditions in relation to chemical-looping combustion [189][190][191][192][193][194][195][196][197][198][199] .…”

Capturing and using CO2as feedstock with chemical looping and hydrothermal technologies

“…With the molecular weights of CaSO 4 (136.1 g/gmol) and the coal (∼13 g/gmol), the mass ratio for CaSO 4 to dry ash free coal is 6.25:1 [=0.625 (136.1/13)]. About 100 to 150 mg of the coal‐CaSO 4 mixture is heated in a quartz bowl from ambient to 900–950°C at a heating rate of 15°C/min in either pure nitrogen or pure CO 2 at a flow rate of 100 cm 3 /min .…”

“…Reaction (1) is highly exothermic, while reaction (2) can be slightly exothermic/endothermic, depending on the OC and the operating conditions of the reactors. The net heat released from both the reactions is equivalent to that of conventional combustion [93][94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110].…”

“…25:1 [=0.625 (136.1/13)]. About 100 to 150 mg of the coal-CaSO 4 mixture is heated in a quartz bowl from ambient to 900-950°C at a heating rate of 15°C/min in either pure nitrogen or pure CO 2 at a flow rate of 100 cm 3 / min [29,76,100,113,150].…”