Near-infrared (NIR) technology can overcome the major problems associated with real-time inline monitoring of process hydrocarbon streams. In the case of the Naptha Steam cracker and other olefin units in the Refinery, PIONA (Paraffins, Isoparaffins, Olefins, Napthenes, Aromatics) are important properties. Naphtha feed streams can in principle be measured on-line by GC techniques, but the parameter measurements required for effective control include PIONA and %Distillation curve, which require long elution times and the added cost of a sample conditioning system.
PONA vs PIONA, what’s the difference?
PIONA is a more exact measurement standard. PIONA considers n-paraffins and isoparaffins to be different. N-paraffins have long straight chains and provide higher cetane values for diesel fuels. The melting point of n-paraffins often occurs between 230-370°C, which results in a worsening of the cold flow properties (cold filter plugging point, pour point) of the diesel fuel. Isoparaffin molecules, such as iso-butane, contain branched side chains. As a result, isoparaffins increase the viscosity, lower pour point, and increase the octane of the fuel. The ratio of n-paraffins to iso-paraffins is an important parameter in some fuel blending operations.
The Total Paraffin content (PONA) is easier to measure with NIR Spectroscopy
For complicated petrochemical mixtures, near-infrared spectroscopy can have difficultly distinguishing the contribution of iso-paraffins and n-paraffins to the absorbance spectrum of the petrochemical product. As a result, PONA, which measures the total Paraffins, Olefins, Napthenes, Aromatics is more straight forward and accurate spectrometric prediction.
Interested in learning if near-infrared spectroscopy can be used in your refinery to measure PIONA? Contact a Guided Wave Sales Representative