Measuring Salinity in crude oils: Evaluation of methods and an improved procedure Montserrat Fortuny a,b , Elisa ˆngela B. Silva b , Agnaldo C. Filho a,b , Rosana L.F. V. Melo b , Ma ´rcio Nele c , Raquel C.C. Coutinho d , Alexandre F. Santos a,b, * a Programa de Engenharia de Processos/Universidade Tiradentes, Av. Murilo Dantas 300, Aracaju 49032-490 SE, Brazil b Laborato ´ rio de Engenharia de Petro ´ leo/Instituto de Tecnologia e Pesquisa, Av. Murilo Dantas 300, Aracaju 49032-490 SE, Brazil c Escola de Quı ´mica/Universidade Federal do Rio de Janeiro, Cidade Universita ´ ria, Rio de Janeiro 21945-970 RJ, Brazil d CENPES/PETROBRAS, Cidade Universita ´ ria Q.7, Rio de Janeiro 21949-900 RJ, Brazil Received 1 February 2007; received in revised form 26 June 2007; accepted 12 July 2007 Available online 7 August 2007 Abstract In this work, a novel procedure is developed to determine the amount of salt for crude oils in which the available laboratory tech- niques are unable to provide accurate salt content values. The technique is based on measuring the salinity of the wash water that is vigorously mixed with the crude oil (forming an emulsion) and then separating it from the water-in-oil emulsion by irradiating micro- wave energy during few minutes. This three step process involves the emulsification of the wash water exempt of salt in crude oil, fol- lowed by the recovery of the water by microwave heating and, finally, the analysis of the salt content using the classical Mohr’s method titration procedure. The novel technique presented here was able to provide reliable information about the salt content on Brazilian crude oils, in a rapid manner, without need of unsafe time-consuming solvent extraction procedures. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Salt content; Crude oils; Emulsions; Desalting; Microwave 1. Introduction In the petroleum industry, there is a great variation in the salt content of crude oils depending mainly on the source and, possibly, on the producing wells or zones within a field. The amount of mineral salts varies with the geologic formation and can be as high as 200,000 ppm [1]. In addition, at the refinery, salt water introduced dur- ing shipment by tanker may contribute to the total salt content [2]. In almost all cases, the salt content of the crude oil consists of salt dissolved in small droplets of water that are dispersed in the crude [3]. The chemical composition of these salts varies, but the major portion is nearly always sodium chloride with lesser amounts of calcium and mag- nesium chlorides. In fact, the presence of salt in the crude oil leads to several problems during transporting and the refining processes, including corrosion of lines, fouling, and also the deactivation of catalysts employed at the refin- ery. As a consequence, the refinery sites are generally equipped with desalting systems which are able to perform the desalination of the crude oil sent to the refinery. The desalting is considered a critical operation at the refinery due to the importance of meeting the specifications of the acceptable quantities of salt and water in the treated oil. For these reasons, measurements of salt and water content in crude oils are very important in all oil industry opera- tions including crude oil production, processing, transpor- tation and refining. Concerning water content measurements, several proce- dures have been described in the literature including on-line monitoring devices and laboratory test methods, as 0016-2361/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2007.07.013 * Corresponding author. Address: Programa de Engenharia de Proces- sos/Universidade Tiradentes, Av. Murilo Dantas 300, Aracaju 49032-490 SE, Brazil. Tel.: +55 79 32182115; fax: +55 79 32182190. E-mail address: alexfersantos@yahoo.com.br (A.F. Santos). www.fuelfirst.com Available online at www.sciencedirect.com Fuel 87 (2008) 1241–1248