Patent ID: 7160437

Claim:
A method for determining the source of coke deposits in overhead equipment in a heavy hydrocarbon thermal conversion process unit for converting heavy hydrocarbon feedstock to lower boiling products, comprising the steps of: (a) introducing an effective amount of at least one nonvolatile metal-containing organic compound into a heavy hydrocarbon feedstock, which said nonvolatile metal-containing organic compound is completely soluble in said heavy hydrocarbon feedstock; (b) converting at least a fraction of said heavy hydrocarbon feedstock containing said nonvolatile metal-containing organic compound in a thermal conversion zone of said process unit to lower boiling products and resulting in a vapor product stream; (c) passing said vapor product stream through at least one piece of overhead equipment associated with said thermal conversion process unit wherein coke deposits form in at least one piece of said overhead equipment; (d) analyzing said coke deposits for the metal of said nonvolatile metal-containing compound; and (e) determining that the source of coke deposits in said at least one piece of overhead equipment results from: (i) condensation of said vapor product stream or (ii) entrainment of feed droplets in said vapor product stream.