decanter centrifuge

Recently one set of 3 phase decanter centrifuge are shipped to Africa for oil tank bottom sludge cleaning project. The tricanter is widely used for oil, water, solids separation industry. The conditions to use the 3 phase decanter centrifuge is as below:

  1. The oil content in the material sludge should be over 10%, and solids phase less than 10%, the solids particle size should be less than 2mm.
  2. The solids phase should be specifically heaviest phase and the two liquid phase must have different densities. For example, oil and water, but solids must be the heaviest. GN produced 2 phase decanter centrifuge is to separate the solids with liquid, the 3 phase decanter centrifuge is to separate the solids- liquid – liquid.
    The working principal of the 3 phase decanter centrifuge is sedimentation, when the sludge is feeding into the 3 phase decanter centrifuge feed tube, the sludge rotates with the bowl, due to the different specific gravity of the 3 phase, their centrifugal force is different. The heaviest phase solids with the greatest centrifugal force, the water’s centrifugal force in the middle, and lightest phase oil with smallest centrifugal force. So that it formed as 3 different layers inside the centrifuge bowl. The solids are pushed out by the rotated screw conveyor, the light liquids( oil) is discharged from the big end bottom fluids out, and the heavy liquids is discharged from the big end top fluids outlet port, they can be collected separately. The water can be sent to waste water treatment facility or to be reused for circulation of the oil sludge treatment process. The solids can be incinerated or be landfilled or sent to Thermal desorption unit. The oil is recovered for sell or to be reused.
    We have 3 standard model 3 phase decanter centrifuge for option, GNSX-350, GNSX-450, GNSX-520.

Recently GN solids control shipped one unit of large mud decanter centrifuge system to our TBM engineering client. The technical configuration is as below:

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1) One unit of 30 inch bowl diameter decanter centrifuge GNLW764A-VFD, which is the largest model decanter centrifuge we produced, we also have smaller model decanter centrifuge, with 9 inch bowl, 14 inch bowl, 18 inch bowl, 22 inch bowl with different bowl length. The big bowl decanter centrifuge should be drived by GN made VFD control panel, for oil & gas industry, it should be positive pressurized VFD control panel, to comply with CNEX or IEC EX or ATEX explosion proof standard as per client’s requirement. For HDD, TBM, Piling etc construction works, the VFD control panel is a non explosion proof control panel, no need a air compressor for air supply, but the main motor drive, ,back drive motor and pump motor are all controlled by the VFD control panel, to adjust the feed rate , to input different differential speed and input different main bowl speed to reach a better separation result. All of the 3 drives are from world famous brand ABB drive.


2) One unit of GNDW-6000L automatic chemical dosing unit, with treating capacity 6000L/h flocculants, which are installed inside the 20ft container, with windows, doors, lighting, air conditioner and others. The chemical dosing system including 3 compartment stainless steel material mixing tank, each compartment with its agitator, a screw conveyor transfer the dry powder flocculants and add to the mixing tank. The prepared chemicals are transferred to decanter centrifuge feed tube by chemical dosing pump, one for use, one as back up. The chemicals and mud are mixed in the decanter centrifuge feed tube, the ultra fine solids or suspended solids are aggregated into larger particles, so that the solids can be separated easily by decanter centrifuge, to get more pure water and drier solids waste.

Recently one batch of decanter centrifuge are working successfully in South America rig site. The equipments list is as below:
2 units of Decanter Centrifuges : GNLW363C-VFD
2 units of Screw Pump : GNG30-075B


The decanter centrifuges are used to treat water based drilling fluids with high G drying shaker, the working process is that the drilling fluids which are treated by solids control equipments, are collected by screw conveyor, the drilling waste are transferred by screw conveyor to high G drying shaker to separate the coarse solids from the drilling waste, then the fluids drop into the catching tank, and the screw pump feed the fluids to GNLW363C-VFD decanter centrifuge to separate the fine solids from the fluids, the clean fluids can be reused to prepare for new drilling fluids. We have stock in GN solids America for faster delivery for South America client, and the electric motor and VFD control panel are comply with IEC EX for class 1 div.1 application. The VFD control panel is positive pressurized control panel with PLC smart control, the main motor, back drive motor and pump motor are controlled by ABB drive.


The decanter centrifuge bowl material is made of duplex stainless steel 2205, the other bowl components are made of stainless steel 316, the screw is made of SS304, the bearing is SKF brand for reliable operation. The feed rate can be adjusted by changing pump frequency.

The discharged solids will be discharged from centrifuge solids discharge trough and collected by cuttings box, which can be transported by waste truck.
Except for decanter centrifuge, GN solids control also produce vertical cuttings dryer for oil based drilling waste treatment, and also oil sludge treatment system for oil , water and solids separation for oil waste sludge, crude oil tank bottom cleaning sludge treatment, etc.

Recently one set of GNLW554ET-VFD decanter centrifuge with 3 phase separation centrifuge, and 2 sets of screw pump, all installed on one skid for convenient shipment. The treating capacity is 15 m3/h.
The detailed technical configuration is as below:


1) Decanter centrifuge ( 2 phase separation centrifuge for solids liquid separation) GNLW554ET-VFD
2) Disc centrifuge ( 3 phase separation centrifuge) GNSD-125
3) 2 sets of screw pump, one screw pump as decanter centrifuge feeding pump, one screw pump as flushing pump of disc centrifuge
4) Complete skid with pipelines and accessories to install all the equipments on one skid for convenient shipment


GN solids control can design and produce customized oil sludge treatment unit with different treating capacity, such as 1m3/h, 2m3/h, 5m3/h, 15m3/h. According to the material information provided by the client, we can decide if all the modular should be utilized or not. Basically a general oil sludge treatment unit including oil sludge picking pump ( vacuum pump ) , pre-mixing tank modular, coarse shaker tank modular, dewatering unit modular, 3 phase separation modular, etc. the customer bought 3 phase separation unit modular, they will use the filter before feeding to the decanter centrifuge, otherwise they should ensure the max solids content should be less than 30% and max solids content is smaller than 1 microns. The less solids content, the better separation efficiency. The decanter centrifuge should separate the solids as much as possible, the fluids enter into the disc centrifuge should be with solids content less than 3% and max solids size no bigger than 5 microns, to avoid any damage of the vertical centrifuge.
Depends on the oil sludge conditions, the user can use proper chemicals, they can select to buy dewatering unit from GN or user their own chemical dosing unit by adding chemicals into the oil sludge, to increase the treating efficiency.

GN solids control can provide customized solution for both oil based drilling cuttings treatment system and oil sludge separation unit, when the system is installed at the rig site, drilling waste management system is proper, when the system is installed in the waste treatment facility, both system can be installed, the customer can use one as per their requirement.


Drilling waste management system including major equipments- vertical cuttings dryer and decanter centrifuge, the oil based drilling cuttings can be transferred by screw conveyor or cuttings vacuum pump to the feeding port of vertical cuttings dryer, the screen basket trap wet solids and accelerate them up to 900rpm with G force up to 420G. the solids discharged from vertical cuttings dryer with OOC below than 5%, but oil content below 5% can not meet the disposal regulation in some countries, they need the oil content below 1%, the solids can be treated by burning unit or Thermal Desorption Unit, which can treat the solids with oil content below 0.3%. The mud treated by vertical cuttings dryer will flow to the intermediate tank, the centrifuge feeding pump transfer the fluids to decanter centrifuge, the separation cut point is 2 ~ 5 microns. The discharged solids can be back to circulation again.


Compared with oil sludge separation unit, the drilling waste management system is with high efficiency, the treating capacity is up to 40m3/h, the oil sludge separation unit with treating capacity 1m3/h, 5m3/h, 15m3/h. the operatio cost is higher.
When the waste is mixed with water based mud drilling waste and oil based mud drilling waste, and the waste is not only from shale shaker, desander, but also from desilter, decanter centrifuge, with much fine solids in the waste, oil sludge separation unit is proper. If you need a customized solution for oil, water, solids separation solution, pls contact with GN freely.