CFD MODELLING OF COMMERCIAL FCC UNIT REGENERATOR

Abstract

Due to high price of catalyst and enerwegeneration of coked or spent catalyst by burning the coke with air is an essential part of the catalytic cracking process. This calls for all round efforts for efficient design of processing system and conceptual changes in system design. To understand the performance of the regenerator, the process variables involved in regeneration must be recognised. The fabrication of regenerator is still an art and considered to be proprietary in nature. Considerable work has been done in the fabrication and designing of the regenerator and its successful adaptation to a specific situation but the theoretical analysis specially in the area of catalyst flow mechanism has not been studied in detail till now. For evaluating conversion, temperature profile and for evaluating hardware and operational changes for improved performance, two mathematical models have been developed in this dissertation work. In the first model, an attempt has been made to develop a mathematical model by applying heat and mass conservation equation, to find the coke conversion and temperature profile in the regenerator. The influence of operating variables on the coke conversion have been analysed and a sensitivity analysis has been done to see the effect of each variable. A computer program is developed for the prediction of conversion and temperature. The results obtained are then compared with the experimental results. In the second model an attempt has been made to develop a mathematical model for catalyst flow based on mass and momentum conservation equation. The calculus of finite difference is used for solving the problem. A computer algorithm is developed to verify various parameters pertaining to catalyst flow mechanism in the regenerator.