Thermochemical Heat Storage Performance of CaO Pellets Fabricated by Extrusion–Spheronization under Harsh Calcination Conditions

Abstract

To improve the CaO/CaCO 3 thermochemical heat storage capacity and the mechanical property of CaO-based material during the repetitive heat storage cycles, CaO pellets were fabricated by the extrusion−spheronization method. The thermochemical heat storage performance of CaO pellets under pressurized carbonation (3−13 bar) and harsh calcination (950 °C, pure CO 2 ) conditions were studied in a dual fixed-bed reactor. The effects of harsh calcination conditions, carbonation conditions, pellet particle size, and pore-forming agent were determined. CaO pellets carbonated under high pressure exhibit a better heat storage performance than calcined limestone. High carbonation pressure greatly offsets the negative effect of harsh calcination conditions on the heat storage capacity of CaO pellets. When the carbonation pressure is 13 bar, the carbonation conversion and heat storage density of the pellets calcined under harsh conditions reach 0.45 and 1423 kJ/kg after 10 cycles, respectively, which are very close to those calcined under mild conditions (750 °C, pure He). The improvement in heat storage capacity of the pellets becomes slight with increasing the carbonation pressure above 5 bar further. An appropriate carbonation temperature range is 800− 850 °C, and a smaller particle size plays a positive but minor effect on the heat storage capacity of CaO pellets. The optimum heat storage conditions are obtained by the orthogonal experiments. The addition of biomass as a pore-forming agent in the pellets apparently increases the heat storage capacity of CaO pellets during the heat storage cycles. CaO pellets possess a high crushing strength of 4.7 N and high fragmentation resistance. CaO pellets prepared using the extrusion−spheronization method seem promising for CaO/CaCO 3 heat storage.

Virtual Special Issue of Recent Research Advances in China: Chemical Looping

“…There is one paper on this topic. Li et al prepare CaO pellets by extrusion–spheronization under harsh calcination conditions, and the thermochemical heat storage performance of the attained CaO pellets is evaluated in a dual fixed-bed reactor.…”

“…Wang et al25 evaluate the nitrogen sorption capability of a series of Al 2 O 3 -supported Mn-/Febased nitrogen carriers during chemical looping ammonia synthesis.There is one paper on this topic. Li et al26 prepare CaO pellets by extrusion−spheronization under harsh calcination conditions, and the thermochemical heat storage performance of the attained CaO pellets is evaluated in a dual fixed-bed reactor.This VSI is part of the series of VSIs on Recent Advances in Selected Energy Research Areas, launched by Energy & Fuels in January 2021. Further information on this series of VSIs can be found in a related editorial (10.1021/acs.energyfuels.0c04048) 27.…”

Enhanced Thermochemical Energy Storage Stability of CaO-Based Composite Pellets Incorporated with a Zr-Based Stabilizer

“…Therefore, combining the incorporation of structure stabilizers and granulation is a promising approach to prepare the desirable CaO-based energy storage materials for the TCES system. Li et al , proved that extrusion–spheronization was an effective granulation method to prepare the CaO-based composite pellets with stable thermal energy storage/release capability. Bai et al also found that the structurally improved, TiO 2 -incorporated CaO-based pellets prepared via extrusion–spheronization exhibited the remarkably enhanced cyclic thermal energy storage/release performance.…”

Alkali Metal Nitrates Promoted MgO Composites with High CO2 Uptake for Thermochemical Energy Storage

“…In particular, TCES outperforms others considering its higher energy density (0.5–1 kW h/kg), extended storage period (theoretically unlimited), and better stability. , High-temperature TCES has recently attracted increasing attention, since it can be integrated to concentrated solar power (CSP) plants. High-temperature TCES has been considered as a promising alternative to molten salt for highly efficient, stable, and long-term energy storage in a CSP plant. , Efforts have been devoted to designing thermochemical materials such as carbonate systems of CaCO 3 /CaO and PbCO 3 /PbO, ,− redox systems of BaO 2 /BaO, Co 3 O 4 /CoO, and Mn 2 O 3 /Mn 3 O 4 , − and ammonia systems of NH 4 HSO 4 /NH 3 and NH 3 /N 2 for high-temperature TCES applications. , …”