Schurco Slurry pumps are excellent solutions for a wide variety of applications where solids are moved via hydrotransport. One very common application for slurry pumps is feeding a hydrocyclone (can also be referred to as a “cyclone”) or separator, both of which centrifugally separate heavier media from lighter media. This classification occurs in the “separation zone”, a conical section of the equipment found below a vortex finder at the top/head box section. There are a variety of design principles that go into cyclone and separators to achieve various cuts of the media. There are performance curves for cyclones and separators, somewhat similar to a pump curve, where pressure drop across the cyclone is defined by a variety of parameters both intrinsic to the cyclone/separator and the pump feeding it.
The slurry pump should be designed to achieve the total head to the cyclone plus the calculated or predicted pressure drop across the cyclone. Making the cut and maintaining a good separation is very dependent on maintaining the specified pressure drop. Control of the pump then becomes critical to holding this pressure. As variable frequency drives (also known as inverters, VFD’s or VSD’s) have gotten less expensive and more common in industry, they have been more and more frequently applied to slurry pumps for cyclone/separator feed applications.
For maintaining optimum performance at the separation point (cyclone/separator), Schurco Slurry recommends controlling pump speed via VFD based on feedback from a pressure transducer measuring pressure at the cyclone/separator inlet. We all understand that steady-state is the goal of any continuous operation, but in practice it is difficult to achieve with variable product feed and other non-steady-state processes all around the mill or plant. Operating a pump in this way may lead to imbalance in your tank levels as the pump speed is varied to achieve a single pressure setpoint at the cyclone/separator, but this can be designed around with adequate makeup water at the pump sumps. Product dilution may occur in the sump when the process media delivering to the sump falls below design parameters, but the unit operation (centrifugal separation of heavier and lighter media at the cyclone or separator) will be maintained at the design point.
Contact your Schurco Slurry sales office or representative for more information on how a solidly designed slurry pump system for centrifugal separation using hydrocyclones and separators can be achieved!