Baker Hughes Process Systems’ WEMCO Depurator is the industry standard for secondary treatment of produced waters.
  The reason for this is that unlike gravity oil/water separators, a WEMCO Depurator is capable of handling emulsions with appropriate chemical additives.

  Proven Performance

  WEMCO separators are the product of decades of experience, continuous research, and innovative development. You get far more experience and engineering with a WEMCO Depurator than you do with any competitive machine.
  The WEMCO Depurator consists of a self-supporting, all steel, skid - mounted tank, with integral float - collecting launders and gas-tight covers. Other features include:
  • A tank interior coated with high - temperature epoxy to provide the greatest corrosion resistance
  • Inspection doors on both sides of the double overflow tank
  • A breather valve
  • A pneumatic liquid-level controller
  • Standpipes equipped with gas intake ports beneath the gas-tight cover
  The power system for the WEMCO Depurator includes:
  • Explosion-proof, 3 phase, 60-cycle, 230/460-volt motors
  • A separate motor for each rotor/disperser mechanism
  • Two 1/4-horsepower gear motors driving the skimmer assemblies

  Major Components of the WEMCO Depurator

  1. Oversized Tapered Roller Bearing with a B10 life exceeding 100,000 hours.
  2. Bearing Housing that keeps dirt and dust away for longer bearing life. The rugged one-piece cast housing holds the bearing and shaft rigid for vibration-free operation.
  3. Dual Seals with a lower-end cap that protects the lower bearing from contamination. A cavity between the upper and lower seals provides a reservoir for lubrication of the lower seal. (For severe duty application, an optional seal for use in a stuffing box style is available.)
  4. One-Piece Oversize Shaft to eliminate balancing problems associated with the two-piece design.
  5. Heavy Gauge Rotor, available in either carbon steel or stainless steel.

  Selecting the Right WEMCO Depurator

  WEMCO Depurator separators are useful in many applications. Because each application is unique, the rated capacity of a specific Depurator model varies with the conditions of a specific application. Before making the final selection of a WEMCO Depurator, please consult our experienced engineers for recommendations. Baker Hughes Process Systems has catalogued the operating results of several hundred installations and stands ready to back up sizing selections.

  State-of-the-Art Operating Efficiency

  • Affords high capacity, maximum removal:
  - Processes up to 171,000 barrels per day of water
  - Removes up to 1500 parts per million of oil in minutes, leaving as little as 10 parts per million of oil or less
  - Removes emulsified oil that gravity oil separators cannot handle
  • Operates effectively in temperatures up to 200 degrees Fahrenheit
  • Mixes chemicals in the machine, eliminating the need for chemical flocculation tanks
  • Provides adjustable skim rate, with

  Separation Process

  The separation process performed by the WEMCO Depurator involves three basic steps:
  Step 1: Aeration. The WEMCO Depurator is composed of four standard WEMCO flotation cells. Each cell is equipped with a motor-driven, self-aerating rotor mechanism. The spinning rotor acts as a pump, forcing fluid through a disperser and creating a vacuum in the standpipe. The vacuum pulls gas into the standpipe and thoroughly mixes it with the fluid.
  Step 2: Flotation. The gas/fluid mixture traveling through the disperser creates a mixing force that causes the gas to form minute bubbles. Oil droplets and suspended solids attach to the bubbles as they rise to the surface.
  Step 3: Removal. The oil and suspended solids gather in a dense froth at the surface, where they are removed from the cell by skimmer paddles into integrated collection launders.

  Self-Induced Gas Flotation

  In the WEMCO Depurator, the removal of oil and solids occurs via “flotation,” a time/rate dependent process. In most applications, the WEMCO Depurator uses produced or associated gas to form bubbles. A pressure of 0.50 to 1.0 ounce is kept to maintain a gas blanket between the liquid level and gas-tight cover. The resulting absence of oxygen prevents the growth of harmful bacteria and also reduces downstream corrosion.
  When air is used, it is induced to the WEMCO Depurator at atmospheric pressure.
  Self-induced mechanical gas flotation such as that performed by a WEMCO Depurator eliminates the need for auxiliary air compressors or blowers.
  Processing is often improved with the aid of a chemical compound injected into the water upstream from the float cell. Such a compound can promote froth flotation by:
  • Breaking oil-in-water emulsions
  • Gathering suspended solids
  • Stabilizing the gas bubbles weir configuration designed to provide independent skim-rate adjustment and minimize skimmings volume
  • Allows for double overflow, with skimmings removed from both sides of the machine to provide the most efficient performance

  Easy Installation and Maintenance

  • The units have minimum space requirements but are large capacity throughout
  • The self-contained unit is mounted on permanent skids to simplify and reduce the cost of transportation and installation
  • Simple controls reduce the need for operator attention
  • A simple, rugged mechanical design makes our units less prone to malfunctions
  • Experienced service technicians are available for routine or emergency maintenance
  • Individual cell mechanisms can be removed for repair without taking the machine off-stream, resulting in less downtime

  Environmental Advantages

  • Maintains clean environment around heavy-duty process industries or oil tank installations
  • Skimmable discharge box allows for collection of the last traces of foreign material, meeting the strictest requirements
  • Eliminates slum, ferric, or clay sludge disposal
  • Reduces skimming disposal: skimmings can be returned to a gravity separation device where free oil can be removed and water returned

  INDUSTRY APPLICATIONS

  Oilfield-Produced Water

  The Depurator machine removes most of the oil droplets from water produced by onshore or offshore oil production. After initial treatment by gravity oil/water separators (such as free-water knockouts, gun barrels, plate separators, and skim tanks) oilfield-produced water can be cleaned by a WEMCO Depurator. This prepares the water for surface discharge or for use in the further production of oil. This prevents formation plugging and reduces workover frequency when reinjecting the water. For stream flooding, the Depurator is used ahead of boiler pretreatment equipment.
  In some projects, wastewater is disposed of in percolation ponds or returned to existing waterways. The WEMCO Depurator has consistently proved its ability to clean the water to local, state and federal standards.

  Refinery Process and Tank Farm Wastewater

  At the refinery, the Depurator wastewater treatment generally follows gravity oil/water separation. Wastewater that can be treated by a WEMCO Depurator includes process waters from:
  • Desalters
  • Tank and water drawoffs
  • Steam stripping condensate
  • Pump gland cooling
  • Treating plant wash
  • Caustic treatment
  • Loading facility washdown

  Petrochemical Wastewater

  During the production of bulk chemicals derived from natural gas or petroleum, wastewater is created. Special characteristics often distinguish this wastewater from the usual oil refinery product, and no single oil/water separation method has proven capable of handling all the compounds produced. The flotation process employed by the WEMCO Depurator has proved to be the best wastewater treatment for many of these oils and suspended solids. Bench tests are recommended for each specific application.