Patent ID: 7896169

Claim:
A hydroclone comprising: a tank having an internal chamber having a chamber wall that includes a tapered section, a fluid inlet, a filtered fluid outlet and an effluent outlet, wherein a diameter of the internal chamber is larger near the fluid inlet than at the effluent outlet; and a stepped filter positioned within the internal chamber of the tank wherein the stepped filter has a plurality of stages, each stage having a successively smaller diameter, the largest diameter stage being located generally near the fluid inlet, and the smallest diameter stage being located generally near the effluent outlet, wherein at least a plurality of the stages include a rise face and a run face; and wherein the fluid inlet is arranged such that fluid entering the chamber through the fluid inlet flows into a region between the chamber wall and the stepped filter, the stepped filter defines a filtered fluid chamber within the internal chamber of the tank, and the filtered fluid outlet is arranged to discharge filtered fluid that has passed through the stepped filter, and the effluent outlet is arranged to discharge a concentrated effluent that has generally not passed through the stepped filter, and the hydroclone is arranged such that during operation a vortex of flowing fluid is formed between the chamber wall and the stepped filter with the filter located substantially in the center of the vortex and such that the stepped filter acts as a cross-flow filter with fluid passing substantially radially through the stepped filter and the stepped filter stages help reduce the size of eddies and countercurrents that occur along a face of the filter during operation of the hydroclone.