Patent ID: 8678711

Claim:
A liquid displacement system operating at an equal mass flow rate and comprising: a storage tank comprising at least one water ballast compartment to store a water and at least one liquid storage compartment to store a liquid, said liquid storage compartment not fluidly interconnected with the water ballast compartment and wherein the structure of the storage tank is configured symmetrically; a volume of a first gas disposed above the water; a volume of a second gas disposed above the liquid and not fluidly interconnected with the volume of the first gas disposed above the water; and further comprising a pump module coupled to the storage tank, wherein the pump module comprises at least one pair of loading pumps and at least one pair of offloading pumps; wherein the pair of loading pumps include a liquid loading pump to load the liquid into the liquid storage compartment and a water offloading pump to offload the water out of the water ballast compartment; and wherein the pair of offloading pumps include a water loading pump to load the water into the water ballast compartment and a liquid offloading pump to offload the liquid out of the liquid storage compartment; and wherein the pair of loading pumps operate substantially at equal mass flow rate to displace the water with the liquid; and also such that the pair of offloading pumps operate substantially at equal mass flow rate to displace the liquid with the water to keep a constant operating weight.