Coupled simulation of convection section and the fluid flow in the furnace tubes H-151 of Distillation Unit of Esfahan Refinery by CFD

In this paper, the simulation of the displacement enclosure of the H-151 furnace unit of the distillation unit in the Isfahan refinery is carried out by using computational fluid dynamics (CFD). This simulation involves simultaneous investigation of fluid flow inside the tubes of displacement enclosure and the flue gas flow of convection section through the tubes as well as displacement enclosure gas flow by adding additional tubes in a two-dimensional state. Grid independency study was done for tube and displacement enclosure and the best grid with numbers of 315000 and 67024 were chosen for tube and displacement enclosure, respectively. The error of temperature and velocity diagrams for tubes with grid numbers 315000 were 0.021% and 0.0569% and for displacement enclosure with grid numbers, 67024 were 0.0712% and 0.0254%, respectively. The velocity and temperature diagrams for the tube, displacement enclosure, and displacement enclosure with additional tubes were obtained and examined. The results show that the flow at the beginning of the tube is turbulent. The fluid velocity inside the tube has been developed from 1.4 meters due to the large length of the tube. The comparison of the results obtained from the displacement enclosure with/without additional tubes has been shown that the temperature and velocity of the gas passing through the tubes are reduced by using additional tubes.