Granular bed filter is one of the most promising technologies for the dust removal from high temperature coal pyrolysis gas. In this work

three-dimensional numerical models were employed to investigate the influence of operation parameters on collection efficiency

especially paying attention to particle deposition characteristics in the bed and outlet particle size distribution. The results show that the operation parameters have different effects on the collection efficiency of particles with the different properties. Under the same conditions

the collection efficiency of granular bed for circulating ash increases more rapidly compared to that of char particles. According to the effective Stokes number (

N

steff

)

the collection efficiency of granular bed can be obviously divided into three regions: difficult separation region (

N

steff

≤0.25)

transition region (0.25

N

steff

0.83) and easy separation region (

N

steff

≥0.83). Dust deposition within the bed exhibits axial attenuation along the gas flow direction

allowing classification of deposited particles into two characteristic types: dispersed particles and congregated particles. In addition

granular bed filtration induces a morphological transition of particle size distribution

transforming the original monomodal profile into a well-defined bimodal structure. A correlation formula of the collection efficiency was developed

providing critical insights for the

engineering design of granular bed filters.