Decanter Centrifuges Offered in Compact Design
Alfa Laval Separation has introduced its new 600 Series line of decanter centrifuges, a solution for wastewater treatment plants with operations from 175 gpm to 350 gpm. The centrifuge line consists of conventional decanters as well as high performance thickening and dewatering models.
With the compact, modular design of the series, the systems can be connected and used right away. The units can thicken sludge from 4 percent to 8 percent dry solids content. Up to 35 percent dry solids can be achieved from dewatering. The systems feature automatic control and continuous operation.
Separation takes place in a horizontal conocylindrical bowl equipped with a screw conveyor. The slurry is fed into the bowl through a stationary inlet tube and smoothly accelerated by a specially designed inlet distributor.
Centrifugal force causes instant sedimentation of the solids on the wall of the bowl. The conveyor, rotating in the same direction as the bowl, but at a different speed, conveys the solids to the conical end. The solids are then lifted clear of the liquid and centrifugally dewatered before being discharged into the collecting vessel. The clarified liquid overflows into the vessel through openings in the cylindrical end of the bowl.
Drive System
The bowl is driven by an electric motor and a V-belt transmission on the shaft at the conical end. Power is transferred to the conveyor by means of a two- or three-stage planetary gear box at the opposite end. The speed difference between the bowl and the conveyor is obtained by a fully automatic backdrive system. Two options are available: eddy current brake or electric motor with variable frequency drive.
Drive System
To protect the gear box, the machine is provided with an overload protection device. The rotating part is carried on a welded box beam frame with main bearings at both ends. It is enclosed in a casing comprising a hinged semicylindrical cover and a bottom section incorporating the solids and the liquid outlets. The entire system is supported by a compact, in-line frame.
Materials
Bowl, conveyor, casing, inlet tube, outlets, and other parts in contact with the process media are made of stainless steel. The 360-degree solids discharge ports and conveyor flights are protected with erosion resistant material, either Stellite or tungsten carbide tiles. The frame is made of steel with an epoxy enamel finish.
Materials
The 600 Series line of decanter centrifuges can be adjusted to suit individual requirements by varying feed rate and rotational speed for optimal separation efficiency, differential conveyor speed for optimal balance between liquid clarity and solids discharge capacity, pond depth in the bowl for optimal balance between liquid clarity and solids dryness.