Increasingly, refineries are producing blend stocks rather than finished products. Such blend stocks are additized after leaving the refinery to produce the final product sold to consumers. The producer must manufacture the blend stock such that, once additized, will meet the specification for the final product. While laboratory certification of the blend stock will typically be done on a hand blend of the blend stock and additive(s), the process analyzers that are used to control production of the blend stocks never see an additized sample. Instead, models are used to predict the value of the additized product based on measurements of the blend stock. The process analyzer measurement(s) of the blend stock serve as inputs into these models which predict the property values that would be measured on the additized final product. This standard describes procedures that are used to assess and validate the performance of the process analyzer system that includes one or more process stream analyzers which input data into a predictive model, the model in turn predicting property values of final product which is manufactured by blending an additive into the blend stock at a fixed additive level.
Current standards on performance assessment and validation of process analyzers deal with situations where the measurements are being made on the final product. Increasingly, the measurements are being made on a blend stock which will later be blended with an additive (e.g. ethanol, biodiesel, etc.) to produce the final product sold to consumers. When process analyzers are used to control manufacture of the blend stocks, a predictive model can be used to estimate properties of the final blended product based on measurements of the blend stock. New standards are required to specify how these predictive models and the predictions made thereby are assessed and validated. This standard will be used by producers who use process analyzers to control and potentially certify measurements on blend stocks.
KeywordsBlend stock, predictive model, additized fuels,
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
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