The hydrodynamics of non-fluidized gas-particle flow through aninclined pipe and an orifice is studied by using the theories of multiphase flow and particulate media mechanics. A series of dynamic differential equations is developed to correlate the gas pressure

interparticle contact pressure

voidage with the properties of gas and particles

the geometry of the bed

and the condition of operation. A numerical method of the dynamic differential equations and an integral method of the simplified dynamic differential equation

which are used to calculate the particle flow rate through an orifice

are also established. The theoretical prediction is in good agreement with the experimental data.