Patent ID: 8645079

Claim:
A method for measuring the properties of petroleum fuels by distillation, comprising the steps of: storing an initial data set of properties associated with a selected light petroleum fraction in computer readable memory, the initial data set of properties including API gravity, RVP, PNA content and true boiling point; generating a molecular ensemble comprising a plurality of molecular species, each with a known pure component API gravity, RVP, PNA content and true boiling point, and storing a pure component data set in the computer readable memory; applying at least one mixing rule to the pure component data set to calculate a concentration of light components of the selected light petroleum fraction based upon the pure component API gravity and RVP; applying the at least one mixing rule to the pure component data set to calculate a concentration of heavier components of the selected light petroleum fraction based upon the pure component PNA content and true boiling point; comparing the API gravity, the RVP, the PNA content and the true boiling point of the initial data set with the pure component API gravity, RVP, PNA content and true boiling point to form a set of comparison data; optimizing the set of comparison data, the step of optimization including application of an objective function S; generating a distribution of the molecular ensemble in terms of volume fractions by minimizing the objective function S as: S = ∑ j = 1 n ⁢ ( ( Tb j - T ′ ⁢ b j ) × W o × 100 / Tb j ) 2 + ( ( P ⁢ % - P ⁢ % ′ ) × W 1 × 100 / P ⁢ % ) 2 + ( ( N ⁢ % - N ⁢ % ′ ) × W 1 × 100 / N ⁢ % ) 2 + ( ( A ⁢ % - A ′ ⁢ % ) × W 1 × 100 / A ⁢ % ) 2 , wherein P ′ ⁢ ⁢ v = ∑ i = 1 n ⁢ P i v ; P ′ ⁢ % = ∑ i = 1 n ⁢ P ⁢ % i = ∑ i = 1 n ⁢ x i P ; N ′ ⁢ % = ∑ i = 1 n ⁢ N ⁢ % i = ∑ i = 1 n ⁢ x i N ; and A ′ ⁢ % = ∑ i = 1 n ⁢ A ⁢ % i = ∑ i = 1 n ⁢ x i A , where x i is the mole fraction of pure component i, P %, N %, A % represent mole percent of paraffin, naphthene, and aromatic content, respectively, in the petroleum fraction, P′ t %, N′ t %, A′ t % represent the paraffin, naphthene, and aromatic contents, respectively, for the petroleum fraction calculated from aggregating pure components in the molecular ensemble using the at least one mixing rule, P v is the true vapor pressure of the petroleum fraction, and P′ v is the true vapor pressure of the petroleum fraction, calculated from aggregation of pure components in the molecular ensemble; generating a set of component concentration data based upon the optimized comparison data; and displaying the set of component concentration data.