Fluid handling – Processes – Affecting flow by the addition of material or energy
Patent
1986-05-09
1988-06-21
Guynn, Herbert B.
Fluid handling
Processes
Affecting flow by the addition of material or energy
252 8551, F17D 116
Patent
active
047519371
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method of reducing friction losses in flowing liquids.
PRIOR ART
It is known that friction loss in flowing liquids can be reduced by intermixing therewith small amounts of a certain soluble polymeric material. In such instance, the polymeric material dissolves in the liquid and forms a solution. When the solution is conducted through a pipeline or other restricted space, the dissolved polymers serve to eliminate or alleviate the tendency of the flow of the solution to become turbulent; that is, to maintain the flow laminar so as to minimize friction loss. This is the phenomenon called the TOMS effect after the discoverer.
The prior art method, however, is not quite satisfactory in that the polymer is susceptible to scission of its chains due to shear stress applied during flow of the solution, leading to instability in the solution. This problem has yet to be solved despite many attempts that have been made with different kinds of polymers.
The present invention seeks to provide a method of reducing friction losses in flowing liquids which is free of the foregoing problem and which can exhibit excellent stability in a given liquid.
SUMMARY OF THE INVENTION
According to the invention, there is provided a method of reducing friction losses in flowing liquids, characterized by adding to a liquid an organo-polymeric microfibril material in an amount of 0.1 ppm-5 percent by weight of said liquid, said material being insoluble and highly dispersible in said liquid.
BEST MODE OF EMBODYING THE INVENTION
The term liquid as used herein includes aqueous or nonaqueous liquids such as oils, lubricants, aqueous lubricants, crude oil, petroleum fractions, solvents and the like.
The term organo-polymeric microfibril as used herein designates a solid organic polymer in the form of microfibrils having an average diameter in the range of 10 .ANG.-5 .mu.m, preferably 50 .ANG.-1 .mu.m, more preferably 100 .ANG.-1,000 .ANG., an average length in the range of 1,000 .ANG.-3 mm, preferably 1 .mu.m-500 .mu.m, and an aspect ratio (length/diameter) of 10-1,000,000.
Polymeric microfibrils of diameters smaller than 10 .ANG. are difficult to make and if not, would be susceptible to scission under shear stress when added to a liquid. Greater diameters than 5 .mu.m would invite precipitation of the microfibrils in the liquid.
Polymeric microfibrils of lengths less than 1,000 .ANG. would fail to suppress turbulence in the flowing liquid. Greater lengths than 3 mm would result in coagulated, precipitated microfibrils in the liquid.
Polymeric microfibrils of aspect ratios smaller than 10 would be ineffective for turbulence reduction. Excessive aspect ratios would lead to entanglement of individual microfibrils and hence precipitation in the flowing liquid.
Polymeric materials to be processed into microfibrils according to the invention should be insoluble but highly dispersible in a given liquid. There may be used for example polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyethylene terephthalate, polymethylmethacrylate, nylon, polycarbonate and copolymers or blends thereof.
Polymeric compounds known for their heat resistance may also be used which include aromatic polyamides, aromatic polyethers, polyetheretherketones, aromatic polyesters, aromatic polyimides and polybenzoimidazoles.
Other polymeric materials that have been found particularly preferable are those which are capable of forming a liquid crystal. Specific examples include aramide fibers such as poly-p-phenylene terephthalamide wet spun from sulfuric acid liquid crystal solution and polybenzobisthiazole wet spun from polyphosphoric acid liquid crystal solution.
Microfibrils formed from polymeric solutions or melts in a liquid crystal state have high molecular orientation and hence high strength so that when placed in a liquid, they can resist scission against increased shearing force applied during flow of the liquid.
By "highly dispersible" is meant th
REFERENCES:
patent: 3843589 (1974-10-01), Wartman
patent: 3938536 (1976-02-01), Metzner et al.
patent: 4263926 (1981-04-01), Drake et al.
patent: 4341684 (1982-07-01), Krantz
patent: 4524158 (1985-06-01), Barber
patent: 4524159 (1985-06-01), Barber
Guynn Herbert B.
Nippon Oil Co. Ltd.
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