Patent ID: 6976497

Claim:
A pressure-differential liquid raising system, comprising: (a) a system inlet at a first elevation for receiving liquid; (b) a system outlet at a second elevation higher than the first elevation; (c) at least one cell at a third intermediate elevation between the first and second elevations, said at least one cell having a cell liquid inlet and a cell liquid outlet; (d) a first liquid-conveying conduit having a first conduit liquid inlet in common with the system inlet at the first elevation, and a first conduit liquid outlet in a respective first said cell at a third elevation, corresponding to a first liquid inlet of the respective first said cell, said third elevation being higher than the first elevation of the first conduit liquid inlet; (e) a second liquid-conveying conduit having a second conduit liquid inlet in common with a second liquid outlet of the respective first said cell, and a second conduit liquid outlet at a higher fourth elevation than the second conduit liquid inlet; and (f) pressure differential apparatus adapted to supply a first pressure differential between the system inlet and the respective first said cell, thereby to cause liquid at the system inlet to flow through the first liquid-conveying conduit to the respective first said cell, said pressure differential apparatus being further adapted to apply a second different pressure differential between the first said cell and one of a downstream said cell and the system outlet, and to simultaneously apply the second pressure differential between the first said cell and the system inlet thereby to cause liquid from the respective first said cell to flow in the downstream direction through the second liquid-conveying conduit along a liquid flow path toward the system outlet as well as to cause a nominal amount of the liquid to flow from the first said cell upstream toward said system inlet.