Oil droplet size distribution

G. J. W. Goudappel, J. P. M. van Duyn-hoven, M. M. W. Mooren 2001, (Measurement of oil droplet size distributions in food oil/water emulsions by time domain pulsed field gradient NMR), /. Colloid Interface Sci. 239, 535. 

The absorption of ozone from the gas occurred simultaneously with the reaction of the PAH inside the oil droplets. In order to prove that the mass transfer rates of ozone were not limiting in this case, the mass transfer gas/water was optimized and the influence of the mass transfer water/oil was studied by ozonating various oil/water-emulsions with defined oil droplet size distributions. No influence of the mean droplet diameter (1.2 15 pm) on the reaction rate of PAH was observed, consequently the chemical reaction was not controlled by mass transfer at the water/oil interface or diffusion inside the oil droplets. Therefore, a microkinetic description was possible by a first order reaction with regard to the PAH concentration (Kornmuller et al., 1997 a). The effects of pH variation and addition of scavengers indicated a selective direct reaction mechanism of PAH inside the oil droplets... 

The pulsed field gradient NMR technique can be readily used for the determination of the water droplet size distribution in W/O emulsions or the oil droplet size distributions in O/W emulsions. Important advantages are the non-invasive nature, the ease of sample preparation, and the feet that pulsed field gradient NMR measures the droplet size distribution of the bulk in contrast with microscopic methods which estimate the size distribution of the surface. Both the proposed matrix method and the iterative curve fitting procedure can be successfully applied in a factory environment. The method can be implemented on a high as well as on a low resolution NMR spectrometer. 

Figure 6 Oil droplet size distribution of on olive oil emulsion, stabilized with hydroxy-propyl mcthylceUkiloae, after different emulsification procedures blender (triangles), ultrasonic probe (squares), and ultrasonic homogenize (stars). Theoretical distributions were calculated from Coulter Counter measurements using a software program, assuming spherical particles.

Schroder J, Kleinhans A, Serfert Y et al. (2012) V iscosity ratio A key factor for control of oil droplet size distribution in effervescent atomization of oil-in-water emulsions. Journal of Food Engineering 111 265-271. 

An increase in homogenisation pressure significantly reduces the oil droplet size, whereas the number of passes mainly affects the 90th percentile of the droplet size distribution and the span, i.e. the width of the particle size distribution (Fig. 2.4). As a consequence an oil droplet size distribution with the majority of droplets below 2 pm may be either achieved at a low pressure with multiple passes or increased homogenisation pressure of, e.g. 400 bar. 

In cooperation with the Karlsruhe Institute of Technology (Prof. Schuchmann) and the Technical University of Dortmund (Prof. Walzel), the impact of atomisation on the oil droplet size distribution was investigated using a pneumatic nozzle or a rotary atomiser. Variation of the protein content at a fixed dry matter... 

Fig. 2.4 Impact of homogenisation pressure and number of passes on the 50th and 90th percentile of the oil droplet size distribution (X50, X90) and the span of an emulsion containing 10% oil. Left-. 0.5% p-lactoglohulin, right 2.0% p-lactoglobulin. Varying amounts of glucose syrup (Dextrose equivalent 35) were added to adjust dry matter content to 45 %...

To investigate the impact of drying oti the oil droplet size distribution and particle ballooning, emulsions with either 0.5 or 10% protein were spray-dried at... 

Table 2.1 Oil droplet size distribution of fish oil emulsions (fresh and reconstituted after spraydrying) stabilised with p-lactoglobulin (P-LG) and hydrolysates thereof prepared by different enzymes (alcalase (A) or trypsin (T))...

Fig. 2.25 50th and 90th percentile of the oil droplet size distribution (X50 and X90) as well as the span for spray-dried emulsions stabilised with p-lactoglobulin or a bilayer with either high or low methoxylated pectin. Left before spray-drying right, after spray-drying in the reconstituted emulsion. Reproduced and adapted with permission from [51]... 

Dispersed oil can consist of oil droplets ranging in size from about 0.5 pm in diameter to greater than 200 pm in diameter. The oil droplet size distribution is one of the key parameters influencing the produced water treating performance. According to Stokes law, the rising velocity of an oil droplet is proportional to the square of the droplet diameter. For equipment that operates on the principle of Stokes law, the diameter of the oil droplet has a major effect on the separation and removal of the oil droplet from the water. 

The capability of a given de-oiling device or system to remove and recover dispersed oil decreases as the droplet size decreases. Oil droplet size distribution is a fundamental characteristic of produced water and must be considered in designing and sizing treating systems to meet regulatory standards for effluent water compliance. 

The dispersed oil droplet size distribution may vary from point to point in a produced water system, and from one system to another. The size distribution is affected by interfacial tension, turbulence, temperature, system shearing (pumping, pressure drop across pipe fitting, etc.), and other factors. The droplet size distributions should be measured in the field when troubleshooting and/or upgrading systems, whenever possible. 

In the absence of data, the generalized relationship in Figure 3.3 can be used for oil droplet size distributions. Since the distribution is linear, it places more volume in smaller-diameter droplets. However, because this straight-line relationship is a very rough estimate, field data should be used whenever possible. For produced water effluent from a three-phase separator, a maximum oil droplet diameter of 250-500 pm and an oil content of 1000-2000 mg/1 can be used in the absence of field data. For first phase de-oiling equipment, an oil droplet diameter of 30 pm with inlet total oil levels less than 100 mg/1 can be assumed for produced water feed to final treating equipment. Operational experience in the area may also provide reliable data from similar existing facilities that can be used to estimate inlet oil concentrations and droplet size distributions. 

Removal efficiency is independent of the influent oil concentration or the oil droplet size distribution. 

In addition to the settling criteria, a minimum retention time should be provided to allow coalescence. As stated earlier, increasing the retention time beyond that required for initial coalescence is not cost-effective for increasing oil droplet diameter. However, some initial retention time can be cost-effective in increasing the oil droplet size distribution. Typically, retention times vary from 10-30 min. It is recommended that a retention time of not less than 10 min be provided in skimmers that have no means of promoting coalescence. To ensure that the appropriate retention time has been provided, the following equation must also be satisfied when one selects d and Lgff ... 

The dispersed oil droplet size distribution in feed water is as follows ... 

The volume percent of the dispersed oil removed by the plate pack is determined by summing the volume percents of dispersed oil droplets contained in the feed water that are greater than or equal to 63.5 pm (see dispersed oil droplets size distribution data given). Therefore,... 

The performance can be described by determining the inlet and outlet oil concentrations and the associated oil droplet size distributions at the equipment inlet and outlet. This information can then be used to define the oil removal efficiency for any given oil droplet size or range of droplet sizes. This concept is further discussed in Chapter 3. 

Sample may contain solids and other non-particles in addition to the oil droplets. Produced water samples often contain solids and other non-oil particles in addition to oil droplets. To determine only the oil droplet size distribution, one must first determine the size distribution for all particles within... 

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