Revamp Trends, Strategies, and Challenges for CDU/Vdu and FCC Units

Upgrading or revamping existing units in the refinery has been a trend followed by many operating companies in recent years. This is due to high profitability gains mainly by utilizing majority of the existing infrastructure and by expanding processing capability of various crudes available in the market. Most of the projects are mainly capacity expansion driven and few are due to environmental regulation mandatory requirements. Most of the projects which are driven by capacity expansion also address existing processing unit operational problems such as inadequate relief disposal system. Refinery revamp projects are inherently challenging due to the several limitations imposed by existing equipment design, existing utility capacities, turnaround timing, and plot space.

Capacity expansion of crude and vacuum units is very commonly done as different crude types are economically available in the market. Many refiners are experiencing unexpected shutdowns routinely due to scaling and fouling in many process equipment’s. Run length of 8 years between scheduled turnarounds is expected from any operating company. Key to avoid foiling and coking is by maintaining adequate velocities in heaters and heat exchangers. Replacement of heat exchangers, trays replacements, burner replacement in heaters, pump upgrades, and ejector system upgrade for higher vacuum are common upgrades. All crude and vacuum units start to perform poorly with time due to scaling and coking. Following systems are commonly affected by high run length - desalting, preheat trains, crude and vacuum tower overhead system fouling and corrosion, low diesel and vacuum gas oil (VGO) recovery, and heater coking. Relief and disposal system are often evaluated after a major revamp.

Capacity expansion of Fluid Catalytic Cracking (FCC) unit is also commonly done which are driven by demand in product volumes. Blower, regenerator cyclones, feed distributor, fractionator trays with packing, fractionator heat exchangers, wet gas compressor. Reactor head replacement is due to corrosion.