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Energy and Exergy Investigations of a Separated-Gasification Chemical Looping Combustion-Combined Cycle System for Power Production

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journal contribution
posted on 20.02.2020, 13:03 by Xiaojia Wang, Xudong Wang, Baosheng Jin
The concept of a novel separated-gasification chemical looping combustion (SG-CLC) system, which is mainly composed of a bubbling fluidized bed as the gasification reactor, a fast fluidized bed as the reduction reactor (RR), and a counter-flow moving bed as the air reactor (AR), has been proposed and evaluated through our previous subpilot scale unit. Extending from the previous work, the present study aims to further investigate the feasibility and potential of this technique for power production. A comprehensive steady-state model integrating various unit blocks has been developed to simulate the operation process of a megawatt-class SG-CLC-combined cycle system based on the ASPEN PLUS simulator. A Chinese Shenhua bituminous coal is used as the fuel with a Fe-based oxygen carrier. During the simulation, the net power production, energy efficiency and exergy efficiency of the combined cycle system, and the work duties of different components are obtained. In addition, the effects of some important operating variables on the system power production performance are elucidated in-depth. The results have shown that the electricity production performance is closely related to the upstream SG-CLC combustion system. At an input thermal power of 1.1 MW and a water flow rate of 750 kg/h, the energy efficiency and exergy efficiency of this novel SG-CLC-combined cycle system can reach high values at 42.9 and 35.6%, respectively. In addition, higher power generation efficiencies can be achieved by properly decreasing the flow rate of feed water, or increasing the temperatures of the RR and the AR.

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