Gas Solids Phase Separation in Multi-Stage Fluidized Beds

Back-mixing of gas and solids can be prevented effectively in both dense and dilute fluidized beds with baffles, resulting from the phase separation, i.e. the formation of ‘gas cushion’ in dense system or ‘solids cushion’ in dilute system, across baffles. In present work, the equilibrium Mach number (Ma_e) is introduced here as the indication of dense and dilute phase in fluidization. Then, gas solids flow across a baffle is treated as equilibrium flow of gas solids mixture through a nozzle. And the principle of gas solids separation through a nozzle can be reasonably explained by a diagram illustrating the effect of throat area on Ma_e. Furthermore, various applications with baffles in fluidization are discussed in light of our model.