Process simulation of a dual fluidized bed chemical looping air separation with Mn-based oxygen carrier

• Published in: Energy conversion and management 2019-09, Vol.196, p.286-295
• Main Authors: Cao, Yang, He, Boshu, Yan, Linbo
• Format: Article
• Language: English
• Subjects: Air flow; Air separation; Air temperature; Bubbling; Carbon dioxide; Chemical looping air separation; Combustion; Computational fluid dynamics; Computer simulation; Dilution; Dual fluidized bed; Flow rates; Flow velocity; Fluid flow; Fluidized bed combustion; Fluidized beds; Fuel combustion; Hydrodynamics; Kinetics; Mn-based oxygen carriers; One dimensional models; Organic chemistry; Oxidation; Oxy-fuel; Oxygen; Oxygen production; Parameter sensitivity; Power consumption; Process modeling; Reaction kinetics; Reduction; Sensitivity analysis
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2019.05.076

•The chemical reaction kinetics of Mn2O3/ZrO2 is determined by TGA experiments.•A one-dimensional model is built for simulating the physicochemical phenomena.•The effects of main operation parameters on the CLAS performance are investigated.•The system specific power consumption can be as low as 0.07555 kWh/m3. Chemical looping air separation (CLAS), a simple and efficient oxygen production technology, can be efficiently integrated with the moderate or intense low-oxygen dilution (MILD) combustion and oxy-fuel combustion technologies. Mn-based oxygen carrier is considered to be a hopeful candidate for the CLAS, but its redox kinetics has rarely been reported. In this work, the most suitable kinetic mechanisms for reduction and oxidation reactions are determined by thermogravimetric analyses. By coupling the obtained redox reaction kinetics and gas-solid flow hydrodynamics, a one-dimensional model of the interconnected fast fluidized bed and bubbling fluidized bed is built using sequential modular approach for simulating the chemical and physical phenomena in the CLAS process. The effects of main operation parameters on the CLAS performance are investigated by sensitivity analyses. The mole fraction of generated oxygen is found increasing with the increments of reduction temperature and air flow rate. Moreover, the system specific power consumption (SPC) is decreased when the temperatures of the two fluidized beds are similar. SPC can be as low as 0.076 kWh/m3 at the oxidation and reduction temperatures of 770 °C, the air flow rate of 50 Nm3/h, and the CO2 flow rate of 23 Nm3/h, which is 18% of the energy requirement of conventional cryogenic air separation system.