Process control

摘要

Method of controlling a process, e.g. a separation, blending or chemical reaction or polymerisation, for which a material X is a feed or a product, in order to keep substantially constant the value Vc of a property P of said product or the product of said process from said feed, or the yield of said process, which method comprises measuring the absorption Dix of said material at more than one wavelength in the region 600-2600nm, comparing signals (i) indicative of said absorptions or a mathematical function thereof with signals (ii) indicative of absorptions Dim at the same wavelengths or a mathematical function thereof for at least 2 standards Sm for which the said property or yield has a known value V, at least one of said standards Smc having a value Vc for said property or yield and controlling said process to ensure that said standard Smc or standard(s) Smc is the standard or standards having the smaller or smallest average value of the absolute difference at each wavelength i between the signal for said material and the signal from the standard Sm.