Differential speed is the difference between the bowl speed and the conveyor speed. The differential is provided by the gearbox which transmits power from the bowl to the conveyor. This is required in order to transport the solid particles that collect on the bowl inner diameter using conveyor. The differential speed determines how long the solid particles remain in the bowl.
The differential speed is decisive for the time that the solid particles remain in the decanter centrifuge, and the compression that it undergoes. It is important and necessary to be able to set the differential speed variably, because changing drilling mud properties in the feed lead to differing conditions, and thus it is possible to keep the total dry solids of the solid at an optimum level. Many centrifuge manufacturers provide a “back drive†which can independently alter the speed. Back drive units are, in effect, hydraulic gear reduction systems used to vary the speed of the conveyor relative to the bowl.
Differential speed adjustment and its advantages
- The differential speed makes it possible to keep the solids in the decanter bowl for the ideal length of time
- Optimum dewatering with fluctuating feed conditions
- Optimum setting of the total dry solids that can be achieved
- Protection against overload and blockage
- Variably adjustable differential speed can make it possible to do the treatment of an extremely wide range of drilling mud
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Published: 02 November 2013
Screw blades spacing is the gap between two neighbouring blades. It is an important parameter for the structure of the screw, because it directly determines the ability to convey solids out of the fluids.
When screw diameter is fixed, the bigger the screw blades spacing, the larger the helix angle and the more chances of suspensions blocking in the screw blades. Big screw blades spacing will also reduce the number of screw blades cycles. The suspensions can not be distributed evenly and it will cause the machine vibrating unsteady.
Conclusion:
1) For suspensions difficult to separate and transfer, the screw spacing should be less, in general 1/5-1/6 of the decanter drum diameter, so that the solids can be transported successfully.
2) For suspensions easy to separate and transfer, the screw spacing should be larger, generally 1/2-1/5 of the decanter centrifuge drum, in order to increase the solids transferring capability.
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Published: 27 October 2013
GN553VFD big bowl big volume decanter centrifuge and screw pump are ready for delivery to Middle East. The centrifuge will be used in oil and gas drilling application. The centrifuge can be used for fine solids separation in drilling mud solids control system or for drilling mud recovery in drilling waste management system.
The screw pump we supplied to the customer along with the decanter centrifuge is NETZSCH brand. The single screw pump is ideal pump for transferring the drilling mud to the decanter centrifuge.
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Published: 19 October 2013
To convey the solids out of the centrifuge, the conveyor and bowl must rotate at slightly different speeds. This is accomplished using a planetary gearbox for belt drive centrifuges. Typically the entire assembly rotates in the same direction, but the conveyor rotates at a slightly slower speed. The conveyor moves the solids to the solids discharge end and the liquid, or effluent, empties out of the weirs at the liquid discharge end.
The depth of the pond is controlled by the adjustment of the weirs, or effluent discharge ports, at the large liquid-discharge end of the decanter bowl. Increasing pond depth increases residence time and separation efficiency while reducing flow capacity. On the other hand, if the other parameters are unchanged, reducing pond depth decreases residence time and the separation of finer particles.
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Published: 13 October 2013
Alfa Laval Centrifuge is often used in oil well drilling application. But the high cost of Alfa Laval centrifuge will add to the total well construction cost. The Europe drilling contractor who did use the Alfa Laval Centrifuge for years has been looking for a more cost effect centrifuge, and then they came to us in 2012 for the first unit of decanter centrifuge.
After 1 year testing of GN centrifuge, GN gained a repeat order of 5 units of middle speed decanter centrifuges and 5 units of high speed decanter centrifuges this year. They also buy shale shaker, mud cleaner, vacuum degasser included in their orders. Please see the sales news at GN Solids Control.
If you are looking for a replacement of Alfa Laval Centrifuge, why not try GN centrifuge?
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Published: 28 September 2013
A decanting centrifuge consist of a conveyor screw inside a rotating bowl. Screw conveyor is an important part of a horizontal decanter centrifuge. Its role is to convery the solids settled against the wall of decanter bowl and push them across a drainage deck, or beach. Dewatering actually takes place on beach, with the decanted solids dischareged through a series of underfow ports.
Screw conveyor is not only a discharging device, but also a factor that determines the treating capacity, service life and separation efficiency.
GN decanter centrifuge screw conveyor are moulded by casting using Stainless Steel 316 as raw material. At the tip of the screw blades, tunsten alloy tile is used as a protection which enables the durability and efficiency of the conveyor. GN also use replaceable tungsten carbon allay ring to protect the solids dischare port.
For more features of GN decanter centrifuge, please see the centrifuge page.
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Published: 21 September 2013