Method for preparing lubrication oils (LAW232)

A process for controlling the manufacture of lubricating oils from a feed having a boiling point of about 350.degree. C. or greater by the steps of introducing the feed into a distillation unit, separating the feed into light, medium and heavy distillates, introducing the distillates into an extraction unit, extracting the distillates to produce raffinates, introducing the raffinates into a dewaxing unit and dewaxing the raffinates to produce lubricating oils, said process comprising:

• (a) obtaining samples of at least one lubricating oil, feed, distillate and raffinate;
• (b) selecting at least one physical, chemical, perceptual or performance properties of at least one of lubricating oil, feed, distillate and raffinate;
• (c) selecting reference samples, said reference samples containing characteristic compound types present in the at least one lubricating oil, feed, distillate and raffinate and which have known values for the property or properties selected in step (b);
• (d) producing a training set by the steps of:
• (1) injecting each reference sample into a gas chromatograph which is interfaced to a mass spectrometer thereby causing at least a partial separation of the hydrocarbon mixture into constituent chemical components;
• (2) introducing the constituent chemical components of each reference sample into the mass spectrometer, under dynamic flow conditions;
• (3) obtaining for each reference sample a series of time resolved mass chromatograms;
• (4) calibrating the mass chromatograms to correct retention times;
• (5) selecting a series of corrected retention time windows;
• (6) selecting within each retention time window a series of molecular and/or fragment ions, said ions being representative of characteristic compounds or compound classes expected within the retention time window;
• (7) recording the total amount of each characteristic compound or compound group selected in step d(6);
• (8) forming the data from steps d(6) and d(7) into a X-block matrix;
• (9) forming the property data selected in (b) for reference samples selected in (c) into a Y-block matrix;
• (10) analyzing the data from steps d(8) and d(9) by multivariate correlation techniques such as Partial Least Squares, Principal Component Regression or Ridge Regression to produce a series of coefficients;
• (e) subjecting at least one unknown sample of at least one of lubricating oil, feed, distillate and raffinate to the steps d(1) to d(3) in the same manner as the reference samples to produce a series of time resolved mass chromatograms;
• (f) repeating steps d(4) and d(8) for each mass chromatogram from step (e);
• (g) multiplying the matrix from step (f) by the coefficients from step d(10) to produce a predicted value for the property or properties for the at least one lubricating oil, feed, distillate and raffinate sample or samples;
• and
• (h) using the predicted values of the property or properties of the at least one lubricating oil, feed, distillate and raffinate sample or samples to control operation of at least one of the distillation unit, extraction unit and dewaxing unit.