A sewage pump series with the innovative "SOLID" (Safe Operation Logic Impeller Design) impeller shape was presented by pump specialist WILO SE from Dortmund, Germany, at the IFAT Entsorga 2012 in Munich.
In the last few years, the careful use of resources by consumers as well as the use of water-saving techniques has resulted in a continuous reduction in average water consumption per head. Parallel to this, the requirements have become more severe, due to changes in the environment. This fact is taken into consideration by the "SOLID" design. The impeller shape, which was already presented at the IFAT Entsorga 2010, has a few new features in 2012. "SOLID" has been specially designed for use in untreated sewage with a particularly high rate of solid materials. In this environment, it can compensate for the disadvantages presented when using other common impeller shapes within sewage treatment that are currently on the market, and can optimise pump operation.
Especially unfiltered sewage with coarse contaminants has proven to often be problematic up to now. It made it difficult to achieve a balance between trouble-free operation and energy efficiency. Impeller geometry and pump housing are decisive considerations for this. They are decisive both for the trouble-free throughput of the fluid as well as for the efficiency of the pump. The "SOLID" impeller combines the advantages of the high efficiency of single and multi-channel impellers with the reliability of vortex impellers. In addition to optimal hydraulic properties for efficiency-optimised and economical operation, it also provides high rates of operational reliability – the most important factor, especially today due to the more complex nature of sewage. It is also able to pump sewage that has a high level of solid material contained within it.
The sewage pumps fitted with the "SOLID" impeller achieve hydraulic efficiency of up to 81 %. According to the manufacturer, they set a new standard in energy-efficient and economical disposal of untreated sewage. In comparison to vortex impellers, almost a quarter of the electricity costs for operating the pump can be saved using "SOLID". Due to the symmetrical design of the impeller and the defined flow guidance in the suction opening, vibrations can also be significantly reduced.
With the "SOLID" impeller developed by Wilo, volume flows up to 670 l/s and delivery heights up to 80 m Hmax can be achieved. Its flow-optimised geometrical design prevents adsorption of solid materials. In addition, flow grooves embedded in the suction area establish slight turbulence which counteracts possible adsorptions. The pump series is available in nominal diameters up to DN350.
An additional benefit is that due to the symmetrical set-up of the impeller and the defined flow guidance in the suction opening, vibrations are significantly reduced. This allows vibrations to be considerably reduced in comparison to single-channel impellers. Due to the special geometry of the impeller, a 4-pin speed is possible even at a nominal diameter of DN350. Motor powers of up to 300 kW are used here.
Additionally, "SOLID" impellers can be provided with the "Wilo-Ceram" coating which can reduce corrosive and abrasive wear when used with aggressive fluids, thereby increasing the lifetime further.
Picture: Due to its optimised impeller geometry, the "SOLID" impeller from pump specialists WILO SE combines low susceptibility to clogging with a high rate of efficiency up to 81% (Image: Wilo)