Application of surfactants for the resolution of emulsions and suspensions in slop oil storage tanks, cleaning, and final disposal

Abstract

In order to provide environmental solutions for the treatment of oily residues (slop oil) from refineries, formulations with surfactants were proposed according to the type of dispersed system of the slop (crude oil emulsified with water and/or solid particles). Samples were collected in 12 tanks located at the Oxialquilados Venezolanos C.A., Barcelona Plant (Anzoátegui, Venezuela), performing physicochemical tests for the identification of the dispersed system (solubility, wettability, stability, water content) and microscopic observations (morphology and particle size). The results indicated heterogeneous slop samples with a water content of 2%–60% vol/vol consisting of single or multiple emulsions, with droplet sizes between approximately 10 and 30 micron; others formed by sludge or suspension (solids/oil/water). For the destabilization of these systems, aqueous and organic cleaning solutions were designed, determining the percentage of oil separated in the bottle tests at optimal and simulated field conditions. Field tests with volume scaling of the slop tank reported efficiencies of 63%, 85%, and 100% when treating the slop TK-17, TK-36, EE, respectively; for the mixture (Pulmon-2) an efficiency of 47%. By combining heat treatment and two demulsifiers was possible to treat the slop TK-17 (multiple emulsion). A considerable volume of water can be drained from the tanks for use in the plant. In conclusion, the surfactant formulas were effective in the recovery of a significant amount of crude oil, making it feasible to return it to the generating entity.