(655b) Numerical Model Development for Flow Analysis of Hot Gas Filters

Hot gas filters are commonly used in coal-fired power plants, such as pressurized fluidized-bed combustion and integrated gasification combined cycle (IGCC) processes and in refineries to recover the catalyst from the fluid bed catalytic cracking units. In the present numerical study, a two dimensional axisymmetric non-isothermal and non-Darcy's law (for flow through porous media) computational fluid dynamics (CFD) based model has been developed for a single candle filter. The schematic of the geometry of the candle filter used in the present study is shown in Figure 1. Experimental data available for the candle filter are used to validate the above model. The agreement between the present model and the experimental data is found to be excellent as shown in Figure 2 a-b. Using this bench mark simulation, inertial resistance coefficients for the filtering element has been derived on an iterative basis. Studies are further extended using these values for the normal (filtering) and reverse mode of operation (cleaning filters using high pressure nitrogen gas) of a real hot gas filtering units. The transient effects involved with the reverse pulsing of the hot gas filter are clearly demonstrated. In addition to this, several design modifications are recommended for improved performance of the hot gas filters.