Method and apparatus for monitoring the molecular weight of hydrocarbon mixtures

Claim 3

The method according to claim 1 wherein said first and second signal providing steps include providing said first and second signals representative of the API gravity and the Saybolt Universal viscosity, respectively, of said hydrocarbon mixture, and wherein said combining step (c) comprises c. combining said first and second signals to provide said third signal representative of said characterization factor, said combining being performed in accordance with said predetermined relationship relating said Saybolt Universal viscosity and said API gravity with said characterization factor, the general form of said relationship being substantially in accordance with the following equation: K A + BG + (C/Vs) where: K the Watson-Nelson characterization factor of said hydrocarbon mixture, Vs the Saybolt Universal viscosity of said hydrocarbon mixture, G the API gravity of said hydrocarbon mixture, and A, B, and C are predetermined constants related to the temperature of said hydrocarbon mixture, and wherein said combining step (d) comprises d. combining said first and third signals to provide said fourth signal representative of said molecular weight, said combining being performed in accordance with said predetermined relationship relating said API gravity and said Watson-Nelson characterization factor with said molecular weight, the general form of said relationship being substantially in accordance with the following equation: MW exp ( ln (exp(a+ bK) + exp(c+ dK)) + m (G- 30)) where: MW the molecular weight of said hydrocarbon mixture, K the Watson-Nelson characterization factor of said hydrocarbon mixture, G the API gravity of said hydrocarbon mixture, and a, b, c, d, and m are predetermined constants.

Claim 4

Apparatus for generating a signal representative of the molecular weight of a hydrocarbon mixture from a source thereof, comprising: a. a first means operatively coupled with said source of hydrocarbon mixture for sensing a physical property thereof representative of the gravity of said hydrocarbon mixture and for providing a first signal representative of said gravity; b. second means operatively coupled with said source of hydrocarbon mixture for sensing a physical property thereof representative of the viscosity of said hydrocarbon mixture and for providing a second signal representative of said viscosity; c. third means operatively coupled with said first and second means for deriving a third signal representative of the Watson-Nelson characterization factor by combining said first and second signals in accordance with a predetermined empirical relationship relating said characterization factor with said gravity and said viscosity of said hydrocarbon mixture; and d. fourth means operatively coupled with said first and third means for deriving a fourth signal representative of said molecular weight by combining said first and third signals in accordAnce with a predetermined empirical relationship relating said molecular weight with said Watson-Nelson characterization factor and said gravity of said hydrocarbon mixture.

Claim 5

Apparatus for generating a signal representative of the molecular weight of a hydrocarbon mixture from a source thereof, comprising: a. a first means operatively coupled with said source of hydrocarbon mixture for sensing a physical property thereof representative of the gravity of said hydrocarbon mixture and for providing a first signal representative of said gravity; b. second means operatively coupled with said source of hydrocarbon mixture for sensing a physical property thereof representative of the viscosity of said hydrocarbon mixture and for providing a second signal representative of said viscosity; c. third means operatively coupled with said first and second means for deriving a third signal representative of the Watson-Nelson characterization factor by combining said first and second signals in accordance with a predetermined empirical relationship relating said characterization factor with said gravity and said viscosity of said hydrocarbon mixture; and d. fourth means operatively coupled with said first and third means for deriving a fourth signal representative of said molecular weight by combining said first and third signals in accordAnce with a predetermined empirical relationship relating said molecular weight with said Watson-Nelson characterization factor and said gravity of said hydrocarbon mixture.