Emulsions problems

Detergents generally are avoided in oils other than for intemal-combustion engines since they may introduce foaming and emulsion problems. 

One of the most widely used techniques across all disciplines is solid-phase extraction (SPE). A simple approach to SPE is shown in Fig. 2.3. These columns provide rapid extraction, minimize emulsion problems, and eliminate most sample handling. 

Always prefer and use such solvent pairs that have a large density difference and a high interfacial tension, for instance water and hexane, as they are less prone to emulsion problems. In contrast, such solvent pairs as water and benzene should not be used in the extraction process,... 

In cases, of acute emulsion-problems substances like-anion exchangers alumina or silicagel are used specifically to resolve the problem by adsorption of the emulsifying agents. In fact, it would be advisable to employ the technique of column chromatography for the effective separation of the analyte as compared to an extraction process. 

What do you understand by the term free energy of the system between two immiscible solvents How would you encounter the emulsion problem in liquid-liquid extractions Explain. 

One disadvantage of the full stream pressurization, of course, is the capital cost of the pump and retention vessel, plus the higher operating expense of the pump. In addition, pumping the full stream may increase the emulsion problem in certain waters. 

Sizing a pressure vessel s liquid-phase section involves four chief factors area, temperature, chemicals, and oil-water residence time required. The first variable, area, has been well established by the water particle in oil settling equation. This equation is only for free water. The second variable, time, addresses the oil-water emulsion problem. Given enough time with a temperature increase and proper chemicals added,... 

A continuous liquid-liquid extractor may be used in place of a separatory funnel when experience with a sample from a given source indicates that a serious emulsion problem will result or an emulsion is encountered using a separatory funnel. The following procedure is used for a continuous liquid-liquid extractor. 

Another major drawback of classical extractions is that additional clean-up procedures are frequently required before chromatographic analyses. Solid phase extraction (SPE) avoids the emulsion problems often encountered in liquid-liquid extraction. A wide range of adsorbents are commercially available and may be divided into three classes polar, ion-exchange, and nonpolar adsorbents. Solid-supported liquid-liquid extraction on Extrelut columns is frequently reported for efficient cleanup of crude tropane alkaloid mixtures. Basifled aqueous solutions of alkaloids maybe transferred to Extrelut columns and the bases recovered in dichloromethane-isopropanol mixture [13]. 

Direct solvent extraction before or after acid or enzymatic digestion has almost superseded die classic protein precipitation methods. Due to die more sensitive detection methods of gas chromatography and mass spectrometry, much smaller amounts of tissue can be processed. Consequently, any emulsion problems that arise are more easily resolved than in the past when several hundred grams of liver and large volumes of solvent were required. 

A particularly interesting part of the pilot involved the treating of produced emulsions. Over the life of the pilot, 93% of the injected surfactant was produced at the production wells, and this situation led to serious emulsion problems. Heating the emulsion to a specific, but unreported, temperature caused the surfactant to partition completely into the aqueous phase and leave the crude oil with very low levels of surfactant and brine. The resulting oil was suitable for pipeline transportation. The critical separation temperature had to be controlled to within 1 0. At higher temperatures, surfactant partitioned into the oil, and at lower temperatures, significant quantities of oil remained solubilized in the brine. Recovered surfactant was equivalent to the injected surfactant in terms of phase behavior, and had the potential for reuse. 

If chemical treatment was not previously used, a chemical that performs well in a similar crude oil and system should be selected for use as a standard. The relative improvement in performance over the standard must be the criterfon for selection of new candidate chemicals. In larger installations that are experiencing severe emulsion problems, many (possibly hundreds) of commercialized emulsion-breaking products or experimental... 

JMULSIONS CAN BE FOUND IN ALMOST EVERY PART of the petroleum production and recovery process in reservoirs, produced at wellheads, in many parts of the refining process, and in transportation pipelines. In each case the presence and nature of emulsions can determine both the economic and technical successes of the industrial process concerned. This book is intended to provide an introduction to the nature, occurrence, handling, formation, and breaking of petroleum emulsions. The primary focus is on the applications of the principles and includes attention to practical emulsion problems. 

Wyatt et al. worked out a GLC assay for atropine and scopolamine in belladonna extract. The extract was solved in 0.1 N sulphuric acid, homatropine hydrobromide was added to this solution as an internal standard, and interfering materials were extracted from the acidified solution with chloroform - and finally a mixture of chloroform and 2-propanol (10 3) if there is an emulsion problem. The alkaloids were subsequently extracted into chloroform (or chloroform-2-propanol) from the basified aqueous layer (pH 9.5 phosphate buffer was used instead of mineral alkali to minimize ester cleavage) and the chloroform extracts were filtered through anhydrous sodium sulphate (previously washed with chloroform). 87 % of the alkaloids were recovered in the first extract, so that two additional extractions gave suffi-... 

This section presents an example showing some emulsion problems. Reservoir and Fluid Description... 

ASP injection for this pilot test was started in January 1995, and the response (about 0.08 PV) was observed on March 30 of the same year. The water cut in the pilot area decreased from 96.6 to 80.7%. An emulsion problem was obvious in this pilot test. From one well sample, the emulsion viscosity was 40 mPa s, which is about twice the viscosity of unemulsifled fluid. However, it was observed that emulsions improved sweep efficiency. Table 13.12 reports the observations from the different injection phases, and Table 13.13 lists the oil concentrations in water after a 30-minute settlement. In this case, the demulsifier was SP169. For more details on this pilot test, see Wang et al. (1997c) and Wang et al. (2006b). 

This section describes the largest Daqing ASP project it is probably the largest ASP project in the world so far. Compared with other small pilot tests, the formation connectivity in this test was an important factor affecting ASP performance. In this case, an emulsion problem was noticed. 

The emulsion problems could be defused by using dichloromethane as the extractant, because of the larger density difference of the phases and the filtration of the reaction mixture on Dicalite Speedex fdter aid prior to the extractions in order to remove solid fines originating from the enzyme preparation [37]. The down-... 

Both of these methods require minimal waste treatment facilities however, evaporation requirements are substantial and initially, as mentioned previously, these are concentration steps only. In addition, cephalosporin C degradation can occur during the evaporation or distillation steps. One major process advantage is that emulsion problems are avoided since there is no solvent partitioning involved. 

Reasonable physical properties-too viscous a solvent will impede both mass transfer and capacity. Too low an interfacial tension may lead to emulsion problems. The boiling point should be sufficiently different from that of the solute if recovery of the latter is to be by distillation. 

The solute descriptors are required in the system coefficient approach. The solute descriptors can be found in Abraham s databases for many compounds. Commercial software (Absolv Pharma Algorithms, Ontario, Canada) is also available for estimating the values of the solute descriptors from the struemre of the compounds. Experimental determination of the solute descriptors is best carried out through the use of multiple water/solvent partition coefficients (Abraham et al., 1999). However, it is difficult to determine the water/solvent partition coefficients using the traditional hquid-hquid extraction, which involves tedious manual operation, compheated sample handhng, and emulsion problems. 

The petroleum industry generally solves the emulsion problem by adding demulsifiers in an ad hoc manner, often based on simple bottle tests. There are many problems associated with this solution. First, the chemical composition of a given well changes with time and can in a worst-case scenario result in a composition totally incompatible with the given demulsifier. Second, little is known about the exact interaction between demulsifiers and other chemical additives (e.g., corrosion inhibitors and flow enhancers ). One may, flierefore, create a new problem by solving another. 

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