Experimental Study of Airlift Pump Performance with S-Shaped Riser Tube Bend

Airlift pump is a type of deep well pumps. Sometimes, it is used for removing water from mines or pumping slurry of sand and water or other solutions. The performance of airlift pump is affected by two sets of parameters; the geometrical and operational parameters. The geometrical parameters include pipe diameter, pump height, design of air injection system, and entrance geometry of the lifting pipe; while the operational parameters involve submergence ratio, conditions of injected air, and nature of lifted phase. Conventionally, airlift pump with bent riser tube is less efficient than that with vertically straight riser tube. However, in real life situations, the use of local riser tube bend or flexible riser tubes is considerably unavoidable. This work investigates experimentally the effects of local bends of the riser tube on the airlift pump performance. A series of experiments on a model airlift pump with three different riser tube configurations, based on the vertical position of local bends, were carried out. The local bends are in the form of an S-shaped like duct. The results showed that setting local bends of the riser tube near the air injection zone improves the airlift pump performance. However, improvement obtained in airlift pump performance is being negligible and, thus, the position of local bend of riser tube does not contribute to improvements in the performance of airlift pump.