Model and Simulation of Thermal Cracking for a Heavy Crude Oil Stream in Oil Refining

Abstract

Since the discovery of petroleum as a source of raw materials for many processes, many techniques able to convert it into different types of products have been developed. One of these methods is thermal cracking, which is based on heating the initial mixture with the purpose of dividing long carbon chains into small chains. In this way, the economic value of the stream highly increased. The reaction of molecular breakdown or decomposition is carried out in a furnace reactor at high temperatures. In order to provide energy to the stream and to increase his internal energy, the equipment uses methane as fuel. The resultant mixture is cooled to promote phases separation inside a splitter. The thermodynamic properties of the system are defined using Chao Seader model and kinetic reaction. The temperature in the furnace was studied to increase the isobutane mass fraction at the end of the reaction. Two sensibility analysis were realized, in the furnace-reactor and in the cooler pre-stripper, to determine their optimal points. In the first case, a temperature of 793.15 K was determined as optimal point to achieve an adequate conversion into isobutane. In the second case, the behavior of the inlet feed temperature in the stripper was obtained. The stripper operation was defined in 6 stages. The inlet stream should be fed at the third stage with a temperature of 400.0 K. At this point, the use of the reboiler is not necessary.