Granular bed filter (GBF) is one of the important technologies for removing dust from high-temperature dust-laden coal pyrolysis gas. This study aims to reveal the deposition behavior of dust particles in the granular bed filter. A CFD-DEM method coupled with the JKR (Johnson-Kendall-Roberts) contact model was used. The effects of filter particle size, superficial gas velocity, and dust particle size on filtration efficiency and deposition characteristics were investigated. The results show that operating parameters have different effects on the capture efficiency of fine dust particles (20 µm). The filter particle size has the greatest effect. As the particle size increased from 1 mm to 6 mm dust removal efficiency decreased, with the maximum decrease reaching 32.2%. The pressure drop per unit length bed decreases as the filter particle size increases. The dust mainly deposits in the top two layers, and the deposition proportion decreases significantly as the bed depth increases. The matching relationship between pore throat size and dust particle size significantly affects dust particle deposition behavior. When the filter particle size increases from 1 mm to 6 mm, the average pore throat size of the bed increases from 0.206 mm to 1.219 mm. When R(the ratio of pore throat size to dust particle size) < 4, 90% of the dust particles are mainly deposited in the top two layers of the GBF. When the R > 4~6, the penetration ability of dust particles is enhanced, and the amount of dust deposited in the first layer decreases significantly. This study establishes a correlation between the effective pore throat size-to-dust particle size ratio and dust particle capture. These findings provide a reference for filter media selection and bed structure regulation in the GBF.

Granular bed filtration;,Coal pyrolysis gas,Dust deposition behavior,Pore throat size distribution