Patent ID: 8118994

Claim:
A method of operating a plant, comprising: determining naphthenic acid corrosivity of a first refinery feedstock, and determining content of a beta fraction of total naphthenic acids in a second refinery feedstock; wherein the step of determining naphthenic acid corrosivity of the first refinery feedstock comprises determination of an alpha fraction of naphthenic acids, wherein the naphthenic acids in the alpha fraction are characterized by at least two of (a) a molecular weight of between 125 to 425, (b) a true boiling point of less than 725° F., (c) a solubility in water at a pH of 6 to 9 between 0.1-2.5 mg/liter, and (d) a solubility of iron naphthenates in oil formed from the naphthenic acids of <0.1 mg/liter; wherein the naphthenic acids in the beta fraction are characterized by at least two of (a) a molecular weight of between 325 to 900, (b) a true boiling point of between 725° F. and 1500° F., (c) a solubility in water at a pH of 6 to 9 between 0.0-0.3 mg/liter, and (d) a solubility of iron naphthenates in oil formed from the naphthenic acids of >0.08 mg/liter; combining the first and second refinery feedstock to form a combined refinery feedstock having a combined naphthenic corrosivity; and wherein the amount of the second refinery feedstock in the combined refinery feedstock is a function of the beta fraction of total naphthenic acids in the second refinery feedstock such that the combined naphthenic corrosivity is less than the naphthenic corrosivity of the first refinery feedstock.