James C. T. Chan and Shaya Movafaghian, both of Houston, recently received U.S. Patent 8,173,017 for “Single-Cell Mechanical Flotation System.”

Texas Business Patent of the Day:  Two Texans have devised a better way to separate oil and other contaminants from water in the hydrocarbon industry.

James C. T. Chan and Shaya Movafaghian, both of Houston, recently received U.S. Patent 8,173,017 for “Single-Cell Mechanical Flotation System.”

The two applied for the patent years ago on October 17, 2008.

The patent assignee is Cameron International Corporation of Houston.

Chan and Movagahian’s invention relates to methods and apparatus for removing suspended matter from a liquid in general and for removing oil and other suspended particulate contaminants from the water stream in the oil field in particular. In one embodiment, the invention relates to removing suspended matter from a liquid on offshore platforms where small footprint of processing apparatus is of important economical advantage both in capital and operating expenditure, according to the patent document.

Gas flotation is one of the most efficient and widely accepted methods used in variety of industries where removal of solid or immiscible liquid phases is of interest. In particular, in the petroleum industry, the ever-increasing volume of associated water produced from the hydrocarbon reservoirs as a side product has become a major issue to be addressed by the producers.

Environmental awareness and regulations are increasingly challenging the producers to achieve a high degree of purification in the treated water streams prior to discharge or re-injection. Gas flotation has proven one of the most efficient and economical polishing processes compared to other methods and available technologies. Simultaneously, the economical penalty for additional water treatment capacity and footprint of apparatus are major factors in budgeting and decision making for the producers. 

The two saw a need for an apparatus to overcome some of the problems in the conventional systems for removing suspended matter from a liquid, particularly in systems used on floating offshore hydrocarbon recovery platforms where the action of the waves upon the apparatus tends to cause the suspended matter to contaminate the recovered water. Further, it would be additionally desirable to reduce the footprint of separation systems for even stationary offshore platforms. 

As a result, their invention provides an apparatus for removing suspended matter from a liquid, which apparatus is particularly suited to be used on floating and stationary offshore hydrocarbon recovery platforms.

It is another object of the present invention to provide a single-cell, mechanical, cylindrical gas flotation system having a reduced footprint, reduced power requirements and reduced capital and operating costs that overcomes the adverse wave effects on floating platforms. 

In carrying out these and other objects of the invention, there is provided an improved apparatus for separating an immiscible phase from another liquid phase by means of creating an abundance of gas bubbles by rotor action in the liquid, and bringing the bubbles in contact with immiscible contaminants, whether in solid or liquid state, and removing the contaminants by promoting attachment of bubbles and contaminants, thus increasing the buoyancy of the resulting floc and floating the floc to the interface to form a froth and removing the froth by means of hydraulic drainage to a collection reservoir. 
 

As a result, a mechanical flotation system having only one cell may be nearly as efficient as one having two or more cells, yet provide an apparatus with a considerably smaller footprint, significantly reduced capital and operating costs, as well as be resistant to floating oil recovery platform wave effects. The single-cell mechanical flotation system may have one skim collection channel that at least partially surrounds a single gas ingestion and mixing mechanism. At least one baffle may direct suspended matter or floc toward the skim collection which may be circular. The gas layer over the liquid is not vented for the purpose of gasification. The vessel may be a cylindrical pressure vessel oriented vertically, and optionally the inlet may be tangential to the periphery of the vessel to impart liquid rotation inside the vessel when liquid is introduced.