Simulation of Stripper Flooding Due to the Increase of Feed Flowrate

Abstract

In this investigation, UniSim software and the Soave-Redlich-Kong (SRK) thermodynamic model were utilized to study flooding in a Naphta stripping column. The objective of this study was to evaluate the impact of increasing feed flowrate from a design load of 121 m3/hr. to 165 m3/hr. on the performance of the plate column. In order to study only flooding in the column, UniSim software was run by keeping the LPG (Liquefied Gas petroleum) and Naphta products within the required specifications. According to the original design specifications of the stripping column, it should not be operated at high feed rates and differential pressure must not exceed 600 mbar. For the purpose of simulation, this value corresponds to a maximum allowable flooding percentage of 85%. The simulation results show that the flooding percentage was 144.5% in the case under study and 83.7% for the design case. Flooding occurred in all parts of the column with diameters of 2 m and 2.7 m. For the case under investigation, the reflux to feed ratio was reduced from 0.45 (design case) to 0.2. The originality of this investigation is the utilization of the temperature profile in the column as a tool to detect the plates where flooding could take place. The column temperature profile during the case under study suggests instability in the plates between trays 5 to 15. It is therefore suspected that flooding takes place mainly between those plates.