Revamping of the convective zone and combustion air preheater (DEKA) of the process' furnaces of an oil refinery

Identifier:  TFG:2397

Handle: https://hdl.handle.net/20.500.11797/TFG2397

Authors:  Redecillas Mulero, Albert

Abstract:
Due to the high global demand of asphalt, ASESA, the biggest producer in Spain, plans on increasing production by 30% on its plant. To this end, each process unit has to be examined to determine whether it can work satisfactorily under the new conditions. The convective and air preheating zone is designed to use up to 35% of the energy provided by burning fuel in the refinery’s furnaces, via the produced flue gas. In the convective zone, a stream of crude oil is heated prior to the atmospheric furnace’s radiation zone. There is also a stream of vapour which is superheated in order to be used in the stripping columns of the process. The remaining energy of the fumes is used to heat air in order to improve combustion efficiency in the furnaces. Presently, it is to be noted that the oxygen composition readings in the chimney, subsequent to the air preheater to extract the combustion fumes, mark 13% versus the 3% read at the furnace exit. This suggests that an undue ambient air entrance to the unit that can negatively affect the heat exchange, in the convective zone and/or the air preheater. This project studies the improvement of these two process units, constructing a mathematical model that validates the present operating conditions in order to accurately predict their behaviour under conditions of 30% augmented flow. Also, modifications are suggested and calculated to improve the convective zone’s performance, as well as other improvements with their basic engineering. Finally, the project is evaluated in terms of risk assessments through the HAZOP method and also to quantify inversions and economic viability.