Multi-scale modeling and control of chemical looping gasification coupled coal pyrolysis system for cleaner production of synthesis gas

摘要

The cleaner and efficient utilization of coal is of great significance to achieve energy conservation enhancement and CO2 emission reduction targets. Coal pyrolysis (CP) and chemical looping gasification (CLG) are both new coal utilization technologies. A cleaner system integrating CP and CLG processes is put forward in this paper to produce high purity synthesis gas with lower CO2 emission for the sustainable development of coal industry, with the aid of multi-scale modeling means including molecular dynamics (MD) simulation, computational fluid dynamics (CFD) simulation, and process simulation. First, MD simulation is executed for CP process with a coal model consisting of 3860 atoms to obtain the optimum operation parameters by mechanism analysis. The obtained coal density of 1.2 +/- 0.11 g/cm(3) is consistent with the experimental result of 1.28-1.33 g/cm(3), ensuring the optimized coal geometry model below 1100 K. Second, the CLG process is simulated by CFD method. CuO is selected as oxygen carrier based on its better heat transfer performance before its residence time is determined based on the fuel reactor (FR) model. Then the CP-CLG system is simulated with Aspen Plus software on the basis of above MD and CFD results. The process simulation result indicates that the purity of synthesis gas produced by CP-CLG system is about 20% higher than single coal CLG system as the latter generates much more CO2. Finally, one control scheme is designed to keep the operational stability of CP-CLG based cleaner synthesis gas production system with the aid of Aspen Dynamics software. (C) 2021 Elsevier Ltd. All rights reserved.