Paper Title
Olefins Plant Optimization Using SFT Technology in Cracking Furnace

Abstract
Thermal cracking of hydrocarbons in the presence of steam is the key unit of an olefins plant. These olefins (ethylene and propylene) are basic materials for obtaining a great important variety of petrochemical products for diverse applications. The feedstock costsfluctuation (ethane, propane, naphtha and others) and high demand of products require the optimal operation of the reactor for hydrocarbon pyrolysis. A novel reactor technology for steam cracking reactors, called Swirl Flow Tube (SFT) as an alternative to improve furnace operation, has been evaluated computationally using ANSYS Fluent. A detailed free-radical mechanism for the reaction kinetics coupled with material, energy and momentum balances of the reactant-product flow along the reactor was considered, using ethane and propane as feedstock. A computational fluid dynamic model (CFD) was adopted to capture the main flow properties of the swirl flow tube and this model allows to attribute the increased heat transfer and pressure drop to a higher wall shear stress.The economic evaluation was carried out in Aspen Process Economic Analyzer, considering capital cost (CAPEX) estimates and operating cost (OPEX) estimates, comparing“straight” tubes vs. SFT-M and SFT-H. Introducing swirl flow tubes result in an increase of heat transfer by 20% compared to the SFT-M geometry and up to 50% compared to "straight" tubes. The increased heat transfer is accompanied by an increased pressure drop compared to a straight tube depending on Reynolds number and geometry.The simulation results confirm the great potential for the application of the SFT technology in steam cracking furnaces because of the lower average wall temperatures and the resulting reduction of coke formation in the reactor coil. Incorporating SFT-M helps to reduce 23% in utilities costs and 17.5% in operational and maintenance costs compared to “straight” tubes. SFT-H CAPEX (best alternative) would contemplate $540,000, which would be retrieved in olefin production in 7 months. Keywords - Olefins, Process Simulation, Cracking, Furnaces, SFT