Rotary control valve for reverse osmosis feed water pump with energy recovery

Abstract

A liquid pumping system includes at least two water cylinders that are each controlled by a hydraulic piston. A rotary valve controls the hydraulic pistons. The rotary valve has an inner unit that rotates within an outer unit. Slots provided between the inner and outer units control the duration, rate and direction of hydraulic fluid supply to the hydraulic piston. A liquid pumping process comprises distributing an initial flow of pressurized hydraulic fluid between the hydraulic cylinders. The hydraulic cylinders move through a cycle in a phased relationship to provide a constant sum of flow rates from the liquid pumps. In a water treating process, feed water is pumped through the membrane unit. Brine from the membrane unit is returned to each liquid pump while that liquid pump is feeding water to the membrane unit.

Dependencies are inferred from the claim text.