The conveyance of shear-sensitive suspensions is a process engineering problem, especially at high back pressures (> 20 bar), for whose solution, only insufficient aggregates have been available until now. Suspensions which are shear-sensitive are, e.g. polymer flocculated sewage sludge, which is dewatered with filtration pressures of more than 15 bar in filter presses. As a prerequisite for high filtration speeds and optimally dewatered filter cakes, it is of great importance that the floc structure is maintained in all pressure ranges.

The DUOSOFT pump, protected by trademark and patent rights, is a double piston pump with common hydraulic drive and controlled suction and pressure valves. Because the hydraulic system is designed as a closed system with low oil volume, it is suitable for „environmental oil“. When open, the valves have practically free through access. The control system is designed so that only very small pressure differences occur in all pressure ranges and the gap flows are therefore negligible. These design characteristics predestine the DUOSOFT pump for pumping shear-sensitive suspensions of all kinds.

THE DUOSOFT PUMP TAPS INTO NEW FIELDS

The DUOSOFT pump is designed for delivery pressures up to 40 bar. The floccule-protecting delivery, which remains unchanged at all pressures, opens up new areas for filtration. In addition to the floccule-protecting conveyance, the DUOSOFT pump system is characterised by its hydraulic control.  This is therefore not subject to the restrictions to which the control range of the usual eccentric screw pumps is subject (maximum and minimum speed as well as possible frequency range 90 to 5 Hz = max. control range 1:20). The hydraulically driven DUOSOFT pump, on the other hand, is infinitely variable between 0% and 100% and can be controlled or adjusted to almost any value. Both advantages together, the floccule protection and the far-reaching controllability, cause the big advantages when using feeding chamber filter presses.