SPECTROSCOPIC DETERMINATION OF AMOUNT OF ONE CONSTITUENT OF A FLUID MIXTURE IN ANOTHER CONSTITUENT OR IN THE FLUID MIXTURE ITSELF, FOLLOWING SEPARATION OF THE MIXTURE INTO ITS CONSTITUENTS

摘要

A method (and apparatus) is disclosed for the spectroscopic determination of the amount ~Nn of one constituent N of a fluid mixture 0 in another constituent n of the mixture, following separation of the mixture into its constituents 1,...,M (where n, N ~ M). The method involves determining the absorptivities a n (n = 1,...,N) of the M constituents from spectroscopic measurements and computing the amount ~Nn from a mathematical expression containing the absorptivities a n and a N which are expressed or expressable as the quotient a n/a N only. The method is insensitive to changes in the absorptivities due to feed variability or changes in upstream process conditions. A modification to the method involves determining the content ~N0 of constituent N in feed 0 from a mathematical expression containing a0, where a0 is the absorptivity of the feed 0, and a N, which absorptivities a0 and a N are expressed or expressable as the quotient a0/a N only.