Emulsion treatment

P. Srijaroonrat, E. Julien and Y. Aurelle, Unstable Secondary OilAVater Emulsion Treatment using Ultrafiltration Fouling Control by Backflushing, 7. Membr. Sci. 159, 11 (1999). 

Some emulsions are undesirable when they occur. In process industries chemical demulsification is commonly used to separate water from oil in order to produce a fluid suitable for further processing. The specific kind of emulsion treatment required can be highly variable, even within the same industry. The first step in systematic emulsion breaking is to characterize the emulsion in terms of its nature (O/W, W/O, or multiple emulsion), the number and nature of immiscible phases, the presence of a protective interfacial film around the droplets, and the sensitivity of the emulsifiers [295,408,451], Demulsification then involves two steps. First, there must be agglomeration or coagulation of droplets. Then, the agglomerated droplets must coalesce. Only after these two steps can complete phase separation occur. It should be realized that either step can be rate determining for the demulsification process. 

In emulsion treatment, resolution refers to emulsion breaking and the separation of the oleic and aqueous phases. Example the breaking and separation of oil-field produced W/O emulsions. 

Mostefa, N.M. and Tir, M. (2004) Coupling flocculation with electroflotation for waste oil/water emulsion treatment Optimization of the operating conditions. Desalination 161, 115-121. 

Srijaroonrat P, Julien E, and Aurelle Y. Unstable secondary oil/water emulsion treatment using ultrafiltration foubng control by backflushing. J. Membr. Sci. 1999 159 11-20. 

The oil producer, on the other hand, must dispose of any solids removed from an emulsion-treatment system by land farming (placement of waste solids in an approved landfill area), shipment to an approved waste facility, re-injection through a disposal well or water-flood system, or shipment to pipeline. These options are governed by the amount of oil associated with the solids, which is directly related to emulsion-breaking capabilities and the amount of solids present. In many cases it may be desirable for an oil producer to blend a portion of oil-wet solids into shipments for pipeline if the specification of less than 0.5% BS W is not exceeded. This method of solids disposal may be the most cost-effective available to the producer. 

In general, emulsion pads limit the performance of emulsion-breaking equipment and chemicals. Both refiners and oil producers view large emulsion pads as symptoms of inefficient emulsion treatment. If the emulsion pad can be eliminated, performance in all aspects of emulsion breaking should improve. 

This chapter will briefly review the nature and the consequential sources of oil-field emulsions encountered in the handling of produced fluids recovered at a wellhead and subsequently processed (Le., ""broken ) at central treatment facilities. The principal factors and agents commonly employed in the separation of both the oil and the water phases found in these produced-fluid streams will be discussed. Subsequently, this chapter will describe sampling and testing techniques that assist in characterizing a process stream s composition and thus in evaluating the effectiveness of a particular separation process. Finally, the major components of a typical oil-field emulsion-treatment facility will be described. Selection and design criteria of appropriate separation equipment will also be presented. 

This section briefly discusses the more frequently employed equipment types that comprise a typical emulsion-treatment plant configuration (Figure 3). Appendix B describes CANMET s pilot-scaled emulsion-treatment facilities located at the Coal Research Laboratories near Devon, Alberta, Canada. 

Appendix B Pilot-Scaled Plant for Heavy-Oil Emulsions Treatment... 

CANMET has a pilot-scaled emulsion-treatment plant (Figure B.l) available to industry for pilot-scaled investigation of heavy-oil-bitumen separation from oil-field-produced waters. This facility is designed to process emulsions at a throughput between 130 L/h (20 barrels per day) and 460 L/h (70 barrels per day) for raw bitumen-oil of API gravity between 8 and 15 (i.e., density between 1014 and 966 kg/m, respectively). 

The unit operations in the miniplant employ proven emulsion-treatment principles free-water knockout, dual-polarity electrostatic treatment (DPET), heavy-oil evaporation (HOE) dehydration, and induced gas flotation (IGF). The overall process configuration provides maximum flexibility and allows for performance evaluation of units on either an individual basis or in various combinations. 

Description of Major Equipment. The principal kinds of equipment comprising the emulsion-treatment miniplant are briefly described in Table B.l, and their interrelationship is presented schematically in Figures B.2 through B.7. 

In many industrialised countries oily wastes are collected and treated in commercial or public emulsion treatment centres. The supply of oil emulsions varies very considerably in type of oils, concentration, contamination with other materials, etc. Following coarse pre-filtration and decantation, oil/water emulsions can be treated very successfully with ceramic membranes. The concentrate is returned to the decanter, and microfiltered again after removal of the free oil, until all oil is removed. The extracted water can be fed into a biological treatment plant, or discharged directly, depending on the composition of the original emulsion and/or local regulations. 

C Progiiard WSR. [Chemurgy Prods.] Modified polyester emulsion treatment imparting soil release and comfort properties. 

The expressions (13.58) describe the dependence of the ablation factor of vertical and horizontal settlers on the parameters of the initial drop distribution k and = Wo/No, the dimensionless time r of emulsion treatment in the electric field, and also on the parameter Ver describing the geometric and hydrodynamic parameters of the settler. 

Fig. 13.18 The ablation factors of horizontal (full lines) and vertical (dashed lines) settlers as functions of duration t of emulsion treatment in the presence of electric field.

In particular, at xq 0 we have 2/(3fe + 8), and at xq oo, 1. Since y/ decreases at small values of xq and grows when xq is large, y/ has a minimum. The ablation factor of a horizontal settler is more sensitive to the duration of emulsion treatment in the electric field than that of a vertical settler. 

The obtained dependences can be used to determine the duration of emulsion treatment in the electric field necessary to achieve a required volume concentration of the disperse phase at the settler exit. 

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