Energy and exergy analysis of chemical looping combustion technology and comparison with pre-combustion and oxy-fuel combustion technologies for CO2 capture

Sanjay Mukherjee,Prashant Kumar,Aidong Yang,Paul Fennell

doi:10.1016/j.jece.2015.07.018

Abstract

Carbon dioxide (CO2) emitted from conventional coal-based power plants is a growing concern for the environment. Chemical looping combustion (CLC), pre-combustion and oxy-fuel combustion are promising CO2 capture technologies which allow clean electricity generation from coal in an integrated gasification combined cycle (IGCC) power plant. This work compares the characteristics of the above three capture technologies to those of a conventional IGCC plant without CO2 capture. CLC technology is also investigated for two different process configurations—(i) an integrated gasification combined cycle coupled with chemical looping combustion (IGCC–CLC), and (ii) coal direct chemical looping combustion (CDCLC)—using exergy analysis to exploit the complete potential of CLC. Power output, net electrical efficiency and CO2 capture efficiency are the key parameters investigated for the assessment. Flowsheet models of five different types of IGCC power plants, (four with and one without CO2 capture), were developed in the Aspen plus simulation package. The results indicate that with respect to conventional IGCC power plant, IGCC–CLC exhibited an energy penalty of 4.5%, compared with 7.1% and 9.1% for pre-combustion and oxy-fuel combustion technologies, respectively. IGCC–CLC and oxy-fuel combustion technologies achieved an overall CO2 capture rate of ∼100% whereas pre-combustion technology could capture ∼94.8%. Modification of IGCC–CLC into CDCLC tends to increase the net electrical efficiency by 4.7% while maintaining 100% CO2 capture rate. A detailed exergy analysis performed on the two CLC process configurations (IGCC–CLC and CDCLC) and conventional IGCC process demonstrates that CLC technology can be thermodynamically as efficient as a conventional IGCC process.

Highlights

Combustion of carbonaceous fuels to produce electricity in power plants emits CO2, which causes climate change [1]
Case 1 is not equipped with CO2 capture and emits 328.3 t/h of CO2
Case 4 with CO2 capture emits only 0.60 t/h of CO2 capturing 99.8% CO2 emissions. This syngas conversion efficiency obtained by the equilibrium reactor models (RGIBBS reactor model in Aspen plus) for Chemical looping combustion (CLC) fuel reactor in our simulation is similar to the efficiency given in Jerndal et al [74] and Chiu and Ku [31]

Summary

Introduction

Combustion of carbonaceous fuels (mainly coal, which is cheap and widely available) to produce electricity in power plants emits CO2, which causes climate change [1]. Coal will continue to dominate power production in the near future due to its lower. Integrated gasification combined cycle coupled with chemical looping combustion (IGCC–CLC) and direct coal chemical looping combustion (CDCLC) are promising technologies to produce clean electricity from coal by efficiently incorporating CO2 capture [10,11,12,13,14]. The OC particles are continuously circulated to supply oxygen for combustion of solid or gaseous fuel(s). This arrangement prevents dilution of products of combustion (steam and CO2) with nitrogen (N2).

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Conclusion