The vacuum crude unit processes reduced crude from the atmospheric column. These heavy oils make this one of the most difficult distillation services in the refinery. Although prone to fouling, it is crucial that this unit operate reliably and efficiently for years at time.

Whether you have a grass roots or revamp application, we can provide you with an optimized, robust solution to meet your most demanding VDU requirements.

Crude vacuum distillation process

The vacuum crude distillation unit takes the reduced crude from the atmospheric column and produces light ends, gas oils, lubricants, and bottoms residue. The focus of the VDU is to produce the highest yield of the most valuable components.

The high velocity column feed must be well understood and carefully distributed into the column flash zone to achieve desired yields and product specs.

The internals vapor velocities inside the vacuum column are very high due to the low pressures. Therefore, the packing in the column must have the lowest possible pressure drop to minimize cracking of the feed, coke formation, and loss of valuable products.

The VDU provides feeds critical to other units in the refinery, so high reliability is essential. This can be challenging as this service processes the heaviest oils in the refinery. The tower needs to run free of shutdowns and maintenance for periods of 4-6 years. The column must therefore be robust from a mechanical and operational standpoint.

The vacuum column typically uses high performance structured packing to maximize product purity while minimizing pressure drop. Sulzer’s Mellapak, MellapakPlus, and Mellagrid are used to meet these needs.