Process and apparatus for analysis of hydrocarbon species by near infrared spectroscopy

Claim 1

In a process for the analysis of a mixture of liquid hydrocarbons comprising a chemical species to determine species concentration, the improvement comprising in combination: a) measuring the near infrared absorption in at least two of the bands of: 1) For benzene: 850-925 nm and/or 1120-1260 nm and/or 1600-1670 nm and/or 1780-1858 nm and/or 2100-2160 nanometers (nm); 2) For toluene: 860-910 nm and/or 975-1000 nm and/or 1214-1230 nm and/or 1600-1670 nm and/or 1780-1858 nm and/or 2000-2160 nm; 3) For xylenes: 850-930 nm and/or 940-990 nm and/or 1015-1045 nm and/or 1120-1214 nm and/or 1320-1530 nm and/or 1600-1670 nm and/or 1780-1858 nm and/or 2000-2040 nm and/or 2100-2160 nm; 4) For alkyl benzenes: 850-900 nm and/or 1015-1045 nm and/or 1156-1264 nm and/or 1214-1230 nm and/or 1214-1264 nm, and/or 1320-1480 nm and/or 1600-1670 nm and/or 1970-2040 nm; 5) For n-paraffins: 1156-1264 nm and/or 1320-1480 nm and/or 1600-1670 nm and/or 1780-1858 nm and/or 1940-2100 nm; 6) For isoparaffins: 1156-1264 nm and/or 1320-1500 nm and/or 1560-1670 nm and/or 1780-1858 nm, and/or 1900-2160 nm; 7) For naphthenes: 1156-1430 nm and/or 1780-1858 nm; or 8) For olefins: 1132-1214 nm; and/or 1600-1670 nm; b) taking each of the absorbances measured, or a mathematical function thereof; c) performing multiple regression analysis, partial least squares analysis, or other statistical treatment using the above absorbances or functions as individual independent variables, d) assigning and applying weighting constants or their equivalents to said independent variables, e) applying the above steps using known compositions to calibrate the instrument and determine said weighting constants or equivalents, f) outputting a signal indicative of the species concentration in the mixture, based on said absorbances or functions.