Slip flow in fixed and fluidized bed plasma reactors

The characteristics of low-pressure gas low through fixed and fluidized bed plasma reactors for the study of plasma-solid reactions are presented. In the plasma fluidized bed reactor (PFBR), solid particles are fuidized at subatmospheric conditions in a resonantly sustained high frequency 2.45 GHz) plasma. The reactor operates in a previously uninvestigated regime of fuidization and microwave breakdown. A modified version of Darey's law is developed to describe and compare fixed and fluidized bed behavior, as well as to rationalize experimental measurements of pressure drop and gas flow in the absence of information about the bed temperature profile. The study has shown for a bed operating in or near the slip flow region that minimum fluidization can be predicted for slip flow fluidization in the absence of a plasma. However, the results of this work indicate that the mass fluxes and pressure drops at minimum fluidization in the presence of a plasma are significantly different from nonplasma fuidized bed. The pressure drop at minimum fluidization, in the presence of a high-frequency electrical discharge, is as much as 25% above that required to levitate the bed contents, and appears to corroborate otherfndings that link increased stability of the bed with the presence of electromagnetic fields.Notation A cross-sectional area of tube, m₂ - B₀ bed permeability - D_p diameter of glass bead, m - D hydraulic diameter, m, defined as the ratio of the cross-sectional area to the wetted perimeter - E electric field strength, J/(C m) - F slip flow correction factor - F_d volume driving force, N/m'm³ - g gravitational acceleration, N/kg - G mass flow rate, kg/s - G_min mass flow rate at minimum fluidization, kg/s - k Boltzmann's constant - K₀ slip correction - L bed height, m - M molecular weight of gas, kg/kg-mole - M_p mass of particles in bed, kg - n_p,e number of density of positive ions or electrons, m^–3 - P_1,2,3 bed pressure below frit, above frit, and above bed, Pa - q electronic charge, C - Q volumetric flow rate of gas, m³/s - R gas constant - Re_p,mf Reynolds number at minimum fluidization - T temperature, K - u superficial gas velocity, m/s - U_mf superficial velocity at minimum fluidization, m/s XKnudsen number - x length variable, m or dimensionlessGreek gl_o coefficient in expression for mean free path - c_n mean free path - gas viscosity, kg/(m s) - ₀ prefactor in expression for viscosity - 3.14159 ... - _g mass density, kg/m³ - hard sphere diameter, m