Interface detection of liquid hydrocarbons using Refractive index measurement technology

Oil refinery supply and delivery stations and loading and unloading facilities of railcars, tank trucks, and ships handle various liquid hydrocarbons and mixtures. Quality assurance using fast and reliable interface detection is necessary when handling more than one liquid hydrocarbon via multi-product distributor. When the interface detection device is connected to an integrated automatic control and unloading system, it can minimize the filling times and operator errors..

A major south Texan refinery recently investigated a reliable way to distinguish between natural gasoline (trip gas) and two butanes (n-butane and iso-butane (2-methylpropane)) in its loading station. The butanes are structural isomers, and thereof they have the same molecular formula, but different structural formula. This causes a difference in how the atoms are arranged, but also the two butane densities (kg/m3) to be very close. The Refractive index is 1.33631 at 15°C for n-butane and 1.32511 at 15°C for iso-butane. The refractive index difference is wide enough to accurately and repeatedly distinguish between the three liquid hydrocarbons. K-Patents Process Refractometer was chosen for four installation locations: one at the railcar unloading station and three at the different product tank inlets. As an added benefit, the K-Patents measurement technology is not affected by the highly potential entrained air and gases in the liquid hydrocarbons.

Ref. 8.01.05 Liquid Hydrocarbon Identification (pdf)