Comprehensive CFD simulation of product yields and coking rates for a Floor- and wall-fired naphtha cracking furnace

A coupled furnace/reactor simulation was conducted to determine product yields and coking rates for an industrial SL-II naphtha cracking furnace fired by both floor and wall burners. The process gas side, as well as the fire side, is simulated using the computational fluid dynamics (CFD) approach. The molecular kinetic model of Kumar and co-workers was used to simulate the naphtha cracking reactions in the reactor. The results show that the asymmetrical design of the furnace results in asymmetrical profiles of flue gas velocity, temperature, and concentration, and leads to poor heat supply of the wall burners on the front wall as well as a high-temperature zone in the crossover section. The recirculation of flue gas caused by the positioning of burners makes the temperature more uniform in the middle of the furnace. Good agreement between simulation and industrial product yields has been obtained without any tuning of the kinetics, indicating that the proposed approach can be used as a guide for further optimization of geometries and operating parameters of naphtha cracking furnaces with burners located both in the floor and in the wall. The coking rate profile reveals that the maximum coking rate is not located at the coil outlet or near the last reactor bend, but rather at a height of 7 m in the second reactor pass.A coupled furnace/reactor simulation was conducted to determine product yields and coking rates for an industrial SL-II naphtha cracking furnace fired by both floor and wall burners. The process gas side, as well as the fire side, is simulated using the computational fluid dynamics (CFD) approach. The molecular kinetic model of Kumar and co-workers was used to simulate the naphtha cracking reactions in the reactor. The results show that the asymmetrical design of the furnace results in asymmetrical profiles of flue gas velocity, temperature, and concentration, and leads to poor heat supply of the wall burners on the front wall as well as a high-temperature zone in the crossover section. The recirculation of flue gas caused by the positioning of burners makes the temperature more uniform in the middle of the furnace. Good agreement between simulation and industrial product yields has been obtained without any tuning of the kinetics, indicating that the proposed approach can be used as a guide for further optimization of geometries and operating parameters of naphtha cracking furnaces with burners located both in the floor and in the wall. The coking rate profile reveals that the maximum coking rate is not located at the coil outlet or near the last reactor bend, but rather at a height of 7 m in the second reactor pass.A