Significance of Halogen in Crude Oil Refining and It’s Test Methods

Abstract

Halogen includes organic and inorganic ions of fluoride, chloride, bromide and iodide. Natural crude oils are fossil fuel and generally not having any halogens. Water is part of exploration out come and it will separate maximum extent however some amount of water remains with crude oils which is main source of inorganic halogens. The source of organic halogens is mainly from process chemicals/additives that are used while exploration/transportation or adulteration at any stage. The presence of halogen at trace level (ppm) in crude oil is having many adverse effects, namely, corrosion, fouling, hydrolysis, deactivation of catalyst etc. on refining processes, Hence, crude oil refiners always try to remove/reduce it before crude oil enters into the distillation unit. The proper monitoring and accurate measurement up to trace level can help to control/mitigate refiner problems, hence, accurate measurement become necessity. There are various test methods available for measurement of halogen/chloride/organic chloride/salt for specific application and having limitations with respect to accuracy, scope of method or detection range and hence, need arises to review all available methods for appropriate application. In this review paper, author has reviewed eight different measurement methods for scope of the methods, application of methods and range of measurement, and important technical information are summarized for easy understanding to users. The test method developed by Nayara Energy for measurement of salts (as NaCl) in crude oil (after and before de-salter) was found to be theoretically more appropriate for crude oil application, which is also accepted by BIS for publication however accurate measurement of organic chloride is still need of hour. Author anticipates that comparative information of various test methods and observations will be highly useful for petroleum fraternity, viz crude oil exploration & refining industries, testing laboratories, research institutes, academic institutes etc.