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.

Process chart of crude oil vacuum distillation process

Pumps solutions
  • MSD axially split multistage pump
    The MSD pump has the broadest hydraulic coverage of any BB3 type multistage pump in the market. There are over 10 000 MSD pumps installed in product pipelines, boiler feed, water injection and even nuclear safety-related services around the globe.

  • BBS and CD between bearings single stage pumps
    The BBS and CD models are API 610 (ISO 13709) type BB2, single stage, radially split pumps. They offer the widest range of hydraulic performance in the industry.

  • OHH overhung single stage pumps
    The OHH is our API 610 (ISO 13709) type OH2 overhung, horizontal, centerline mounted, single stage, radially split process pump.

  • CP horizontal radially split multistage barrel pump
    CP ISO 13709 / API 610 Type BB5 radially split barrel casing pumps are used in both high-pressure oil production and high-temperature refinery applications.

  • GSG diffuser style barrel pump
    The GSG pump is the least costly form of ISO 13709 / API 610 Type BB5 high-pressure barrel pumps. The GSG back-to-back rotor stack is supplied on low- density services where rotor stability is critical.
Mass transfer technology
  • Mellapak™ and MellapakPlus™
    Mellapak is the most widely used structured packing worldwide. MellapakPlus™ is the latest generation of structured packing. With the enhancement of the geometric structure of conventional Mellapak™, the pressure drop is much lower and the maximum capacity can be extended by 50% compared to Mellapak™.

  • Structured grid packings - Mellagrid, Nutter Grid, F-Grid
    Grids are developed for severe services that are susceptible to fouling, erosion, coking, and high solids content. Grids are installed in rigid modules stacked in successive layers with a fixed orientation, thus minimizing the overall pressure drop while simultaneously increasing tower efficiency.

  • Fixed valve trays
    The V-Grid tray technology utilizes fixed valves, such as MVG™, MMVG™, which combines the attributes of sieve and float valves.

  • Feed inlet devices
    We offer a variety of feed inlet devices. To choose the appropriate equipment, the required purpose of the feed inlet device has to be taken into account. Vapor distribution, liquid pre-separation, foam suppression, breaking of momentum or any combination of these phenomena have to be addressed.

  • Sulcol™ for Windows
    Use this Sulzer tool to design your mass transfer columns.
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