Session: 01-04-01 Fluid Machinery Symposium

Paper Number: 87023

87023 - Clogging Behavior of Different Impeller Types of Sewage Pumps at Speed Variation 

Nonwoven wet wipes are the most hazardous substances that cause clogging of sewage pumps, due to the increasing amount of wet wipes in sewer systems. The clogging of sewage pumps causes a considerable additional economic expense every year, which can be avoided by well-functioning sewage pumps. An additional problem to be considered is the reduced water consumption, which increases the concentration with the increased use of wet wipes in the wastewater. With demand-driven pumping of wastewater due to large diurnal fluctuations, pumps are speed-controlled as the price of frequency converters decreases.

The current advice when speed variation in wastewater pumps are used, affects the minimum velocity in the pipes. The question that needs to be answered is the effect of speed variation on the pumping of wet wipes in wastewater pumps. Until now, there is no answer. The study investigates how speed influences the clogging phenomena of wastewater pumps. The pumps have been approved at a test stand in a laboratory that is designed for functional tests on wastewater pumps. During the test the operating behavior is logged and indicates how clogging influences the pumping performance. Those tests have been done for a long-time performance test, in which the wastewater is pumped in a loop for 60 Minutes.

The presentation deals with the results of clogging behavior in view of speed variation for different impeller design, e.g. vortex-, single blade- and screw blade impellers. An overall comparison of the results advices to selection and operational actions. During the test procedure the clogging is observed with a high speed camera, that the clogging on the impeller can be visualized. This helps to understand the clogging and self-cleaning ability of impellers better.

Evidence of the influence of the speed on the clogging of wastewater pumps could be proven. The behavior of the susceptibility to clogging of the wastewater pumps was very different. The type of impeller as well the speed are the most influencing characteristics that influence clogging. These findings can be used to adjust operating parameters in pumping stations and reduce the clogging tendency of wastewater pumps.

Presenting Author: Paul Uwe Thamsen KSB SE / TU Berlin