Modeling and Optimizing Gas Solid Distribution in Fluidized Beds

In fluidized bed reactors, uniform distribution of gas and solids is critical to achieve the desired hydrodynamic and kinetic performance. For FCC units, Technip Energies uses a proprietary distributor design to terminate both reactor risers and spent catalyst lift lines to distribute the exiting gas-solid stream into a fluidized bed.

In Technip Energies’ Resid FCC unit, air and spent catalyst is distributed from an upward flowing stream into catalyst bed for coke combustion on catalyst. Proper distribution is key to achieve a uniform coke burn and an even temperature profile throughout the bed. In PropyleneMax^TM Catalytic Cracking (PMcc^TM) technology, the riser reactor also terminates in a fluidized bed, requiring proper distribution of the hydrocarbon vapor and solid mixture into the reactor bed, which is key to providing adequate contact for further cracking to valuable products. This paper discusses Technip Energies’ gas-solid distribution technology and its recent work to develop an improved distributor for use as a riser termination device in both the PMcc reactor and the RFCC regenerator to achieve improved performance.

Use of CFD modeling to screen and evaluate the initial concepts and optimize the final selected concept will be presented. Furthermore, CFD results from both reactor and regenerator side will be discussed with a new distributor design showing benefits of improved gas solid distribution on hydrodynamic and kinetic performance. The performance matrix used to quantify the benefits of the optimized design will be highlighted

For regenerator modeling, coke burning kinetic description is provided through proprietary combustion kinetic equations. The results provide detailed qualitative mapping of the regenerator behavior in terms of flue gas composition, temperature distribution including afterburning, regenerator bed density in both axial and radial planes. The CFD coupled with spent catalyst regeneration kinetics is used to quantitative evaluate regenerator performance and benefits of technology upgrade