Patent ID: 8596989

Claim:
A dual injection airlift pump, comprising: a hollow, tubular pump body having a lower portion defining a lower inlet end and an upper portion defining an upper outlet end opposite the lower inlet end, the pump body defining a liquid flow passage disposed axially therethrough, at least one portion of the pump body having a plurality of perforations formed therein defining radially disposed gas flow passages through the pump body, wherein the lower portion of the hollow, tubular pump body has a first plurality of gas flow passages disposed radially therethrough and the upper portion of the hollow, tubular pump body has a second plurality of gas flow passages disposed radially therethrough; at least one gas delivery collar surrounding the portion of the pump body having gas flow passages defined therein, the gas delivery collar and the pump body defining a toroidal gas delivery plenum therebetween, wherein the at least one gas delivery collar comprises: a first gas delivery collar surrounding the lower portion of the pump body, the first gas delivery collar and the lower portion of the pump body defining a first said toroidal gas delivery plenum therebetween, the radially disposed gas flow passages permitting delivery of a gas under pressure from the gas delivery plenum to the liquid flow passage of the lower portion of the pump body; and a second gas delivery collar surrounding the upper portion of the pump body, the second gas delivery collar and the upper portion of the pump body defining a second said toroidal gas delivery plenum therebetween, whereby the radially disposed gas flow passages permit delivery of a gas under pressure from the gas delivery plenum to the liquid flow passage of the pump body in order to pump a liquid through the pump body through buoyant effect of the pressurized gas; and an impervious sleeve disposed within the upper portion of the pump body, the sleeve having a lower end sealed to the pump body and an open upper end, the sleeve having a height less than the upper portion of the pump body, the sleeve and the upper portion of the pump body defining an annular, axially extending flow path joining the liquid flow passage above the open end of the sleeve, the gas flow passages of the upper portion of the pump body permitting gas under pressure to flow from the second toroidal gas delivery plenum into the axially extending flow path and then into the liquid flow passage in an axial direction.