Ralph C. Little

Drag reduction in capillary tubes as a function of polymer concentration and molecular weight

Abstract An equation derived from Virks universal drag reduction relation has been shown to adequately describe the drag reduction of aqueous solutions of polyethylene oxide condensates over a wide range of molecular weight and concentration. Virks intrinsic concentration was found to be an inverse function of polymer molecular weight. The limit of usefulness of polymer critical concentration as a normalizing aid in the treatment of drag reduction is indicated and the polymer aggregation hypothesis for drag reduction is briefly discussed.

Some physical properties of soap/solvent systems and their relation to the solubility parameter of the solvent

Abstract Certain solubility-linked physical properties of soap/solvent systems have been shown to be functions of the solubility parameter of the solvent. The lowest critical solution temperatures for zinc and lead stearates occur in solvents having a solubility parameter of 8.9. Maximum swelling of lithium and sodium stearate/solvent systems occurs at a solvent solubility parameter of 9.3. In addition, the gel/jelly-sol transition temperatures for aluminum dilaurate/solvent systems have been shown to be an approximately linear function of solvent solubility parameter. A qualitative explanation for the observed results is based upon an analogy to high polymer/solvent systems.

BREAKING EMULSIONS OF WATER IN NAVY FUEL OILS

Abstract Stubborn emulsions of distilled and artificial sea water in mixtures of Navy Special Fuel Oil (NSFO) and Navy Distillate (ND) have been broken by applying several approaches suggested by Lawrence some years ago. The effect of NSFO content, demulsifying agent structure and concentration, polymer concentration and salt concentration on the demulsifying process was studied. It was found that a commonly-used wetting agent, sodium di-2-ethylhexyl sulphosuccinate, was a particularly potent demulsifier and apparently superior to several commercial demulsifiers. The addition of a water-soluble polymer of high molecular weight intensified demulsifier action, while that of small quantities of an alkaline salt promoted separation in the most difficult cases, particularly those involving distilled water as the discontinuous phase.

The drag reduction of poly(ethylene oxide)-carboxylate soap mixtures

Abstract The interaction of poly(ethylene oxide) with a homologous series of carboxylate soaps has been detected through measurements of drag reduction under turbulent flow conditions. The plots of percentage drag reduction at constant polymer concentration versus soap molarity are quite similar to literature data reported for the effect of several anionic surfactants on the reduced viscosity of a nonionic polypeptide. At low soap concentrations, the drag reduction of poly (ethylene oxide) is suppressed and falls to a minimum value. As the concentration is increased further the drag reduction rises above the value in pure water to one almost 75% greater in the stronger soap solutions. When the soap concentration corresponding to the minimum in the plot ( C M ) is plotted against the critical micelle concentration (cmc) the simple relation C M = 0.225 cmc is obtained. Such a result strongly suggests a cooperative micelle formed between soap and polymer at this point. Furthermore, the enhanced drag reduction obtained is consistent with the model of surfactant molecules hydrophobically bonded to the polymer chain in which repulsion between adjacent polar surfactant groups promotes expansion of the polymer coil.

Chemical demulsification of aged, crude oil emulsions.

The viscosities and the rates of evaporation for six tanker crudes of various geographical origins were studied to ultimately determine the resultant effect on the chemical demulsification of their seawater-in-oil emulsions. A 5to nearly 15-fold increase in viscosity was observed upon loss of their more volatile fractions. In spite of initial differences in viscosity, five of the six crudes had similar evaporation rates. I t also was found that the evaporation rate of volatiles from a 50% seawater-in-crude-oil emulsion was not greatly different from that of the raw crude. Aerosol OT was found to be an acceptable chemical demulsifier of the emulsions generated from these crudes. As expected, low temperatures decreased the rate of demulsification for a given crude. Moreover, the demulsification rate was significantly influenced by the demulsifier concentration. In general, emulsions generated from the less viscous crudes were more easily broken probably as a result of lower concentrations of naturally occurring emulsifier and lower viscosity of the continuous phase. The artificial seawater used was made up by dispersing and dissolving the recommended amount of ‘kea salt” (Lake Products Co.) in distilled water. Methods. A Virtis homogenizer was used to form the emulsions. Equal volumes of oil and artificial seawater were added to the special flask, and emulsification was complete after a 5-min period of high-speed mixing. All rheological measurements were made with both a Brookfield Model LVT rotary viscometer and a series of Cannon-Fenske Capillary viscometers. Sample temperature was controlled by means of a constant-temperature bath maintained at f O . l “C. The processes used in emulsion production and destabilization may be represented as follows: emulsion making

The effect of additives on the aerosolization of JP-5 jet fuel

Abstract The May spinning top aerosol generator was used to generate aerosols from neat Navy jet fuel and selected dispersions of three types of polymer additives in the jet fuel. The additives selected were Oppanol B-200, a Vistanex Series, and a proprietary antimisting additive designated as FM-9. The mass median diameter (MMD) of the droplets produced was studied as a function of additive concentration and spinning top velocity for each additive. In the case of each additive, the MMD significantly increased with concentration at constant RPS. The effect of the Oppanol B-200 was comparable with that of FM-9 with respect to its influence on the MMD.

Flammability and storage studies of selected fire-resistant fluids

Using the Naval Research Laboratorys mist flammability apparatus, several commercial samples of invert water-in-oil emulsions, designed for possible application as fire-resistant hydraulic fluids or lubricants, were screened for fire resistancy. Their stabilities under storage conditions for approximately a 2-year period were also assessed. For comparison purposes, two other commercial fire-resistant fluids were also screened, viz. a water-glycol solution and a phosphate ester. The Navys current petroleum type hydraulic fluid, 2190-TEP, was employed as the reference fluid. In addition to fire resistancy tests, the drop size distributions of water microdroplets in the separated emulsion layers were also determined.

The correlation of drag-reduction effects with polymer intrinsic viscosity

Abstract Drag-reduction and viscosity data for four polymer families have been analyzed and correlated. A two-constant equation has been found to successfully organize the intrinsic concentration and intrinsic viscosity data for all four families. In the absence of intrinsic viscosity—molecular weight relationships the analysis provides a meaningful index of drag-reduction efficiencies among polymer homologs and suggests the means by which various families may be effectively compared.

Some Observations on Drag Reduction in Polyacrylic Acid Solutions

Polyacrylic acid was chosen as the model polyelectrolyte for drag reduction experiments designed to study selected variations in solution pH and salt concentration. Measurements were carried out in both a turbulent pipe system and a rotating disk apparatus. The observed drag reduction had a strong dependence on solution pH; it increased with pH up to 6 and then leveled off at higher pH values. Progressive addition of salt (sodium chloride) to the polymer solutions decreased the percent drag reduction sharply. The shear stability of polyacrylic acid was shown to be superior to that of polyethylene oxide.

Fire-inhibiting behavior of high molecular weight polyisobutylene in JP-5 jet fuel

The fire-inhibiting behavior of polyisobutylene (PIB) solutions in JP-5 jet fuel has been examined using a rotating disk mist generator combined with an ignition source. The correlation of the mass median diameters (MMD) of fuel mists with their fire-inhibiting behavior is discussed and a preliminary analysis of the data usinf the concept of an antimisting factor, in analogy to earlier drag reduction work, is attempted. The effect of molecular weight on the MMD is also presented. The concentration dependence of the MMD for PIB solutions in JP-5 is compared with a proprietary fire-inhibiting formulation.