(213h) Olefins Plant Optimization using SFT Technology in cracking furnaces

The thermal cracking of hydrocarbons in the presence of steam is the fundamental unit of an olefins plant. Ethylene and propylene are essential materials for obtaining a variety of petrochemical products for diverse applications. The feedstock costs fluctuation and global olefins market demand require the optimal operation of the reactor for hydrocarbon pyrolysis. A novel reactor technology for steam cracking furnaces, called Swirl Flow Tube (SFT) as an alternative to improve furnace operation, has been evaluated computationally using ANSYS Fluent, based on a detailed free-radical mechanism. Cracking furnaces of an existing olefins plant were used to study this technology due to its low production and operational failures because of coke formation leading damages to the material of the coils.

They present $6.2 million per year losses in ethylene revenues and up to $70 million per year in OPEX costs. A computational fluid dynamics model (CFD) was adopted to capture the main flow properties of the swirl flow tube. The economic evaluation was performed using Aspen Process Economic Analyzer, considering CAPEX and OPEX estimates, comparing “straight” tubes (original design) vs. SFT-M and SFT-H. The simulation results confirm the considerable potential for the application of SFT technology. Incorporating SFT-M (“the best alternative”) would reduce $0,6 per ton of ethylene in utility costs and 17.5% in operational and maintenance costs compared to “straight” tubes. It guarantees operational continuity, increases ethylene production of up to 13.5%, reduces OPEX by $0.6 per ton of ethylene, and rises furnace run length of up to 80 days because of reducing coke formation, without affecting mechanical integrity of coils. The SFT-M CAPEX contemplates $577,823.00, which would be retrieved in olefins production in a period no longer than six months.

Index Terms—: Pyrolysis furnaces, tubular reactor, reactor modeling, olefins production, Swirl Flow Tube