Minimising product giveaway (TIA)
Refiners are responsible for controlling their blends of gasoline and diesel fuels to meet specifications for multiple parameters.
Ametek Grabner Instruments
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Gasoline producers, for example, seek to control octane number (RON/MON), vapour pressure (RVP), distillation points, aromatics, oxygenates and more. The precise control of blend components to comply with specifications is necessary to meet legal requirements and reduce costs.
Grabner Instruments, a subsidiary of Ametek Inc., is a developer and manufacturer of automatic petroleum testing equipment to determine the different values of gasoline and butane as products.
Gasoline is a high value product. Butane, on the other hand, is relatively low cost. Thus, adding butane to a gasoline blend improves refinery operating margins. Notwithstanding, a refiner must still comply with regulations for RON/MON and vapour pressure. The addition of lighter butane significantly increases the vapour pressure, but maximum vapour pressure values are strictly regulated in many areas of the world as a means for limiting emissions. At the same time, minimum ON need to be strictly observed to guarantee the quality of gasoline grades, since refiners typically demand higher prices for higher gasoline grades.
Increasing the octane number adds value to the gasoline, while decreasing the vapour pressure requires adding low volatility components. Either approach is costly for refinery operations, since increasing the octane rating or decreasing the vapour pressure requires blending more expensive components into the gasoline. Thus, the closer that gasoline can be blended to the required ON and RVP ratings, the less the refiner gives away as result of blending costs.
The industry estimates that in the United States the average octane giveaway is 0.7/bbl, whereas the average vapour pressure giveaway per barrel is 0.4 psi (2.8 kPa). A major contributor to product giveaway is the reproducibility of the ASTM or EN methods used to monitor compliance with gasoline specifications (see Figures 1 and 2). Another contributor is the precision of the testing equipment used.
Based on production data from the US and the European Union, the consolidation of octane and vapour pressure giveaways results in an annual loss of more than $3.3 billion in the US and more than $1.9 billion in the European Union (see Table 1).
Therefore, testing precision is vital to reducing giveaway costs. To minimise RVP giveaway, an exact analysis of the vapour pressure, in combination with the exact dosing of butane, is required. The Minivap on-line RVP tester from Grabner Instruments is known to offer high reproducibility of 0.1 psi (0.7 kPa) as well as ASTM/EN standard compliant analysis of the vapour pressure of finished gasolines or butanes in the blender.
When a Minivap on-line analyser is installed in a Global Technics butane blending system, a precise blend can be achieved directly on the pipeline. The Global Technics blending system can achieve tight dosing to within 0.05% of butane. A combined RVP analyser/butane blending system can achieve a positive ROI in a matter of months, and even a medium sized refinery can save more than a million dollars per year.
This short case study originally appeared in PTQ's Technology In Action feature - Q2 2019 issue.
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