The System Design And Computational Fluid Dynamics Simulation For Chemical Looping Combustion

CO₂ as the main greenhouse gas, increasingly affecting the changes in global climate and ecological environment, and threaten the survival environment of human, also take troubles to the social economic development. Chemical looping combustion as a new technology which is low energy consumption and low pollution to achieve the high concentration of CO₂, take the Fe₂O₃/Al₂O₃ as oxygen carriers, creat a detailed system design method for the chemical looping combustion system, and get the key design parameters of the serial fluidized bed reactor, use the fluid dynamic similar theory, designed and built a cold model of the thermal experimental facility, and researched the system stability, pressure balance and fluid dynamics of the colde model. And based on the fluid dynamic software(Fluent), studied on the cold and thermal simulation for the designed system, and that is useful for the design parameters slection.A fast fluidized bed and bubble fluidized bed reactor are respectively as the Air Reactor and the Fuel Reactor, based on chemical kinetic balance, mass balance, pressure balance, fluid kinetic analysis, got a more comprehensive design program, improved the existing design theory for the serial fluidized bed system.According to the fluid kinetic similarity, design a cold model test bench correspond to a thermal CLC system about 40kW, AR's height and diameter are respectively equal to 2.2m and 0.1m, FR's height and diameter are respectively equal to 0.39m and 0.2m, and take the quartz sand as the recyclable materials that the particle density and diameter are respectively equal to 2917kg/m3 and 0.213mm. When AR and FR's bed materials are respectively equal to 3.2kg(the bed material height about 0.24m), 5.34kg(the bed material height about 0.11m), the fluid wind speed of AR and FR are respectively 1.8².4m/s(about 1¹.3ut), 0.18⁰.22m/s(about 4.25⁵.19umf), the Loopseal's fluid wind speed, loosen wind speed, side wind speed are respectively 1⁴umf, 0.5².5umf, 0.5¹.0umf, it can meet the design conditions, and proved the scheme is feasible.Based on the Fluent6.3.2, the cold simulation shows that, for AR, when the fluid wind speed equal to 1.5m/s, the axial mean void fraction is about 0.945, it showed as the fast fluidized bed. When the fluid wind speed equal to 0.8m/s, it showed as the turbulent fluidization, and be consistent to the bed cold Test of axial pressure drop; for FR, when the wind speed equal to 0.15⁰.2m/s, the mean axial void fraction is about between 0.572 to 0.629 that it is consistent with the theoretical design.As the Eulerian model for the FR's chemical kinetic simulation, the result shows, CH4 partial pressure and temperature are the main factors to affect the reaction rate, the greater of the partial pressure and the higher of the temperature, the greater of the reaction rate. The grater of the fluidization velocity and the more air bubbles in the fluidized bed, the greater of the void fraction. When the wind speed is between 0.2m/s to 0.25m/s, the bed void fraction is varied from 0.68 to 0.73, In addition, with the increase of partial pressure, the generated gases will dilute the fuel gas, and it will be affect the reaction rate.