Chemical-Looping Combustion and Gasification of Coals and Oxygen Carrier Development: A Brief Review

Abstract

Chemical-looping technology is one of the promising CO2 capture technologies. It generates a CO2 enriched flue gas, which will greatly benefit CO2 capture, utilization or sequestration. Both chemical-looping combustion (CLC) and chemical-looping gasification (CLG) have the potential to be used to generate power, chemicals, and liquid fuels. Chemical-looping is an oxygen transporting process using oxygen carriers. Recently, attention has focused on solid fuels such as coal. Coal chemical-looping reactions are more complicated than gaseous fuels due to coal properties (like mineral matter) and the complex reaction pathways involving solid fuels. The mineral matter/ash and sulfur in coal may affect the activity of oxygen carriers. Oxygen carriers are the key issue in chemical-looping processes. Thermogravimetric analysis (TGA) has been widely used for the development of oxygen carriers (e.g., oxide reactivity). Two proposed processes for the CLC of solid fuels are in-situ Gasification Chemical-Looping Combustion (iG-CLC) and Chemical-Looping with Oxygen Uncoupling (CLOU). The objectives of this review are to discuss various chemical-looping processes with coal, summarize TGA applications in oxygen carrier development, and outline the major challenges associated with coal chemical-looping in iG-CLC and CLOU. OPEN ACCESSEnergies 2015, 8 10606

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

“…However the large supply of coal dictates that investigation into CLC with solid fuels is also important. Indeed, the use of solid fuels has extended during the last years, and an extensive work has been done in the use of solid fuels Wang et al, 2015a;Adanez et al, 2012). When using gaseous fuels, the fuel can be fed directly to the fuel reactor as the fluidization agent.…”

“…However many of these methods increase production costs for the OC and therefore decrease the economic feasibility of such systems (Porrazzo et al, 2016;Abad et al, 2007). The use of raw metal ores has been investigated by numerous groups as a method of providing a readily available and cheap oxygen carrier for the chemical looping process Wang et al, 2015a;Adanez et al, 2012;Imtiaz et al, 2013). The objective of this paper is to compile the latest work involving the use of natural ores as OCs in CLC processes.…”

Experimental Model Development of Oxygen-Enriched Combustion Kinetics on Porous Coal Char and Non-Porous Graphite

“…However, almost half of reserves in the world are low-rank coal, and there is a policy burden due to the high price of high-rank coal. Therefore, in recent years several efforts have been made to develop technologies for utilizing the relatively inexpensive low-rank coal [1,2].…”

“…A wire-heating reactor was used to measure the temperature of low-rank coal char, and a spot-ignition model was suggested for the evaluation of the intrinsic reaction kinetics and the prediction of the ignition temperature [6]. A pressurized wire-heating reactor was also used to predict the gasification kinetics of low-rank coal char in a CO 2 atmosphere. The study indicated that the reaction kinetics were affected by elevated pressure (up to 30 atm) and high temperature (up to 1723 K) [7].…”

Numerical Modeling of Oxygen Carrier Performances (NiO/NiAl2O4) for Chemical-Looping Combustion

“…In addition, the second step of the process uses air to re-oxidize the oxygen carrier and emits only oxygen depleted air. From an environmental point of view, this technology is innovative and provides energy with greenhouse gas emission-free and even negative contribution for combustion of biomass and biogas [7,8]. The core technologies of CLC processes are fluidized or packed bed reactors.…”