Patent ID: 6969467

Claim:
A method of conducting hydrate-based desalination or water purification in a hydrate fractionation column, said method comprising: introducing hydrate-forming substance into a lower, hydrate formation region of said hydrate fractionation column where saline or otherwise polluted water to be treated is present, said water to be treated being under temperature and pressure conditions sufficient for hydrate to form upon introduction of said hydrate-forming substance into said hydrate formation region, whereby positively buoyant or gas-assisted positively buoyant hydrate forms within said hydrate formation region, allowing said hydrate to rise within said hydrate fractionation column toward a hydrate dissociation region of said hydrate fractionation column, allowing said hydrate to dissociate to release fresh or purified water and said hydrate-forming substance, said fresh or purified water collecting in said upper, hydrate dissociation region of said hydrate fractionation column, and collecting fresh or purified water product water, wherein a fresh or purified water region of said hydrate fractionation column extends downwardly from said hydrate dissociation region to a level corresponding approximately to the top of a region where said hydrate is stable and a mixture of fresh or purified water, hydrate, and gaseous hydrate-forming substance is present within said fresh or purified water region of said hydrate fractionation column, said method further comprising removing a portion of said fresh or purified water from an upper region of said hydrate fractionation column and reintroducing said removed portion of fresh or purified water into said hydrate fractionation column at a lower, reintroduction region thereof, said reintroduction region being located at a lower region of said fresh or purified water region of said hydrate fractionation column and above the level corresponding to the top of said region where hydrate is stable, whereby a fluid flow circuit is established that extends from said reintroduction region of said hydrate fractionation column, up along said fresh or purified water region of said hydrate fractionation column, and down along a fresh or purified water down-flow conduit through which said removed portion of fresh or purified water flows to said reintroduction region, wherein the density of said mixture of fresh or purified water, hydrate, and gaseous hydrate-forming substance that is present in said fresh or purified water region of said hydrate fractionation column is less than the density of said removed and reintroduced portion of fresh or purified water such that a density-differential-driven circulatory system of fluid automatically rising at an enhanced rate within said fresh or purified water region of said hydrate fractionation column and flowing down along said fresh or purified water down-flow conduit is established.