Apparatus and method for eliminating champagne effect in compressed air energy storage systems

Claim 2

Apparatus for providing a continuous hydrostatic head in a compressed air energy storage system, said system including a water reservoir at ground level, an underground water storage cavern, and a fluid path connecting the cavern and the reservoir, the apparatus comprising: a generally vertical hydraulic compensating shaft defining at least a portion of said fluid path and having a central axis and an upper end fluidly communicating with the reservoir; means for fluidly coupling a lower portion of said shaft to said cavern; and at least one pressurized water discharge nozzle disposed adjacent an inner surface of said shaft at a discharge level spaced from the reservoir and oriented to discharge a stream of water into the shaft in a direction which imparts a rotary motion to a column of water in the shaft so that air bubbles in the water column collect in the vicinity of the axis of said shaft and a tubular column of water is formed which is relatively free of air bubbles and is disposed along walls of the shaft and above the nozzles.

Claim 3

The apparatus of claim 1 further comprising a plurality of vanes mounted to the inner surface of said shaft configured to induce movement of the air bubble and water mixture in said direction of rotation as the air bubbles rise in said shaft to facilitate the concentration of the air bubbles along the axis of said shaft, said vanes being sized so that said shaft remains substantially unobstructed.

Claim 5

The apparatus of claim 3 wherein said entry level is located above said discharge level so that said water discharged through said nozzle keeps rising bubbles from entering said opening.

Claim 6

The apparatus of claim 1 wherein said discharge level is located at a distance below the surface of the reservoir which is about 10% of the vertical height of the shaft.

Claim 7

In a compressed air energy storage system, said storage system including a reservoir of water at ground level, an underground storage cavern and a fluid path connecting the cavern and the reservoir, apparatus for providing a continuous hydrostatic head on the water in the cavern by controlling the flow of bubbles forming in the water along the fluid path, the apparatus comprising: a generally vertical hydraulic compensating shaft in said fluid path along which the bubbles form and having a central axis and an upper end fluidly communicating with the reservoir; means for fluidly coupling a lower portion of said shaft to said cavern; a plurality of vanes mounted to the inner surface of said shaft configured to induce movement of the air bubble and water mixture in a direction of rotation as the air bubbles rise in said shaft for concentrating the air bubbles along the axis of said shaft; at least one nozzle disposed adjacent an inner surface of said shaft at a discharge level, said nozzle being adapted to cause water forced therethrough to enter said shaft in said direction of rotation thereby forcing the bubbles to collect along the axis of said shaft; and said fluid path including a water intake port within said reservoir, said shaft having an opening at an entry level located above the discharge level, and a water intake path fluidly connecting said intake port and said opening in said shaft to provide a substantially bubble free column of water in the fluid path above the entry level.

Claim 8

In a compressed air energy storage system, said storage system including a reservoir of water at ground level, an underground storage cavern and a fluid path connecting the cavern and the reservoir, apparatus for providing a continuous hydrostatic head on the water in the cavern by controlling the flow of bubbles forming in the water along the fluid path, the apparatus comprising: a generally vertical hydraulic compensating shaft in said fluid path along which the bubbles form and having a central axis and an upper end fluidly communicating with the reservoir; means for fluidly coupling a lower portion of said shaft to said cavern; a plurality of vanes mounted to the inner surface of said shaft configured to induce movement of the air bubble and water mixture in a direction of rotation as the air bubbles rise in said shaft for concentrating the air bubbles along the axis of said shaft; at least one nozzle disposed adjacent an inner surface of said shaft at a discharge level, said nozzle being adapted to cause water forced therethrough to enter said shaft in said direction of rotation thereby forcing the bubbles to collect along the axis of said shaft; and said fluid path including a water intake port within said reservoir, said shaft having an opening at an entry level located above the discharge level, and a water intake path fluidly connecting said intake port and said opening in said shaft to provide a substantially bubble free column of water in the fluid path above the entry level.

Claim 11

A method according to claim 7 wherein the step of rotating comprises the step of injecting a stream of pressurized water into the shaft so that the stream imparts rotation to the water in the shaft.

Claim 12

The method of claim 8 wherein the step of rotating further comprises the step of: imparting a rotary motion to air bubbles rising vertically upward through water in the shaft at a point in the shaft below the point where the stream is injected whereby the rotary motion of the bubbles causes a corresponding rotary motion of the water in the shaft.

Claim 13

The method of claim 8 wherein the step of injecting includes the step of orienting the water stream upwardly so that the water and air bubbles in the shaft move spirally upwardly to collect the bubbles along the axis of the shaft.