Mono and di organophosphite esters as crude oil antifoulants

In a method for reducing fouling of surfaces contacted with crude oils and residual crude oils during refinery processing thereof, said refinery processing comprising a successive series of continuously practiced steps including:

• A. heating a crude oil in a heat exchanger to a temperature in the range from about 100.degree. to 200.degree. F.,
• B. desalting said crude oil by the substeps of
• 1. turbulently mixing with the so heated crude oil from about 3 to 8 parts by weight of water for each 100 parts by weight of said crude oil,
• 2. breaking said emulsion, and
• 3. separating the resulting aqueous phase from the resulting crude oil phase,
• C. further heating said resulting crude oil in a post desalter heat exchanger to a temperature in the range from about 200.degree. to 500.degree. F.,
• D. still further heating said resulting crude oil in a furnace to a temperature in the range from about 500.degree. to 700.degree. F.,
• E. fractionally distilling in an atmospheric still, the so heated, crude oil at temperatures ranging from about 300.degree. to 650.degree. F. and at pressures ranging from and including atmospheric up to about psia. and condensing the distillates until an atmospheric residue remains which boils above a temperature in the range from about 300.degree. to 650.degree. F.,
• F. heating said atmospheric residue in a furnace to a temperature in the range from about 650.degree. to 800.degree. F while maintaining subatmospheric pressure of from about 5 to 14 p.s.i.a.,
• G. fractionally distilling in a vacuum still the so heated atmospheric residue at temperatures ranging from about 800.degree. to 1000.degree. F, under subatmospheric pressures of from about 1 to 5 p.s.i.a. and condensing the distillates until a viscous pitch results which boils above a temperature in the range from about 1 to 5 p.s.i.a. results, p1 H. heating said viscous pitch in a furnace to a temperature in the range from about 1000.degree. to 1500.degree. F at subatmospheric pressures of from about 1 to 5 p.s.i.a. and
• I. passing said so heated pitch into a flash zone maintained at a temperature in the range from about 860.degree. to 900.degree. F at pressures ranging from about 50 to 350 p.s.i.g.,
• the improvement which comprises the steps of:
• a. admixing with at least one material selected from the group consisting of said crude oil, said atmospheric residue, and said viscous pitch a small amount of at least one additive preceding at least one of the respective and processing steps in said series designated above as (A) through (I), and thereafter
• b. subjecting said resulting mixture to the remaining successive processing step(s) in said series,
• said additive being at least one compound selected from the group consisting of thiophosphate esters and thiophosphite esters, said thiophosphate esters being characterized by the general formula ##STR8## where:
• R.sub.1, R.sub.2, and R.sub.3 are each independently selected from the group consisting of hydrogen, an addition complex of hydrogen with an amine, alkyl, aryl, alkaryl, aycloalkyl, alkenyl, and aralkyl, provided that in any given such phosphate ester at least one and not more than two of each of R.sub.1, R.sub.2 and R.sub.3 are each hydrogen or an addition complex of hydrogen with an amine, and said thiophosphite esters being characterized by the general formula ##STR9## where:
• R.sub.4, R.sub.5 and R.sub.6 are each independently selected from the group consisting of hydrogen, an addition complex of hydrogen with an amine, alkyl, aryl, alkaryl, cycloalkyl, alkenyl, and aralkyl, provided that in any given such phosphite ester at least one and not more than two of each of R.sub.4, R.sub.5, and R.sub.6 are each hydrogen or an addition complex of hydrogen with an amine.