Simulation, Optimization and Control of Heavy Oil Upgrading Processes: Application to a Delayed Coking Unit

摘要

Petroleum refineries have faced many challenges to remain competitive in the world fuels market. If, on the one hand, recovered crude oils are getting heavier and there is a decreasing demand for heating and residual fuels, on the other hand, the demand for transportation fuels and more value-added products is increasing, renewing the interest of the refineries on the bottom-of-the-barrel residue upgrading. However, the feedstock for heavy oil conversion units comprises large, multifunctional molecules. Thus, characterize it adequately is a complex task, making complicated the obtaining of accurate kinetic models. This paper proposes a proper approach to simulation, optimization and control of a delayed coking unit by using Aspen Plus software. A novel procedure to represent a given feed material by pseudocomponents is described and a stoichiometric model based on known fractional conversions was developed. PID control was implemented in the system and satisfactory results were achieved. This supposes that the proposed methodology can be useful to obtain more appropriate predictions of behaviour and yield for processes with difficult dynamics and it can be applied in several ways, as on the tracking of processes as well as on new optimization techniques and advanced control.