Compositions and methods for inhibiting fouling in hydrocarbons or petrochemicals

1. An antifoulant composition for inhibiting fouling on structural parts of a system exposed to a fluid hydrocarbon or petrochemical stream, said antifoulant composition comprising (1) at least one polyalkylene anhydride ester (“PAAE”) dispersant, wherein said dispersant is a polyisobutenyl succinic anhydride derived ester (“PASAE”) with a molecular weight, Mw, of about 1,000 to about 25,000, wherein said polyisobutenyl succinic anhydride ester (“PASAE”) includes a polyol moiety, wherein said polyol moiety is represented by the formula

wherein R is a polyisobutenyl moiety, said dispersant providing a stable dispersion when mixed with said fluid hydrocarbon or petrochemical stream, wherein said fluid hydrocarbon or petrochemical stream comprises heavy crudes or crude blends,

wherein said at least one structural part is selected from the group consisting of hydrocarbon or petroleum storage units, heat exchangers, piping, pumps, flow meters, valves, desalters, preheat furnaces, furnaces, coker preheaters, cokers, distillation columns, fractionation columns, atmospheric columns, pipe stills, debutanizers, reactors, fluid catalytic cracking units, fluid catalytic cracking slurry settlers, hydrocracking units, steam cracking units, thermal cracking units, visbreakers, reflux units, condensers, and scrubbers.

2. The antifoulant composition of claim 1 , wherein said antifoulant composition further comprises at least one additional antifouling component selected from components (2), (3), (4), and (5) wherein:

component (2) is an alkylphenol sulfide (“APS”);

component (3) is an alkyl phosphate phenate sulfide (“APPS”);

component (4) is a polyalkylene succinimide (“PAS”); and

component (5) is a polyalkylene thiophosphonic acid ester (“PETPA”).

3. The antifoulant composition of claim 2 , wherein said alkylphenol sulfide APS is present and is selected from the group consisting of nonylphenol sulfide and dodecylphenol sulfide.

4. The antifoulant composition of claim 3 , wherein said nonylphenol sulfide and said dodecylphenol sulfide are both present and are each overbased with calcium.

5. The antifoulant composition of claim 1 wherein 100 ppm of said dispersant, based upon 1 million parts of said fluid hydrocarbon or petrochemical stream provides said stable dispersion.

6. The antifoulant composition of claim 1 , wherein the fluid hydrocarbon or petrochemical stream is present at a temperature range of about 250° C. to about 550° C.

7. An antifoulant composition for inhibiting fouling on structural parts of a system exposed to a fluid hydrocarbon or petrochemical stream, said antifoulant composition comprising

(1) at least one polyalkylene anhydride ester (“PAAE”) dispersant, wherein said dispersant is a polyisobutenyl succinic anhydride derived ester (“PASAE”) with a molecular weight, Mw, of about 1,000 to about 25,000, wherein said polyisobutenyl succinic anhydride ester (“PASAE”) includes a polyol moiety, wherein said polyol moiety is represented by the formula

wherein R is a polyisobutenyl moiety, said dispersant providing a stable dispersion when mixed with said fluid hydrocarbon or petrochemical stream, wherein said fluid hydrocarbon or petrochemical stream comprises heavy crudes or crude blends, wherein the fluid hydrocarbon or petrochemical stream is present at a temperature range of about 250° C. to about 550° C.; and

at least one additional antifouling component selected from components (2), (3), (4), and (5) wherein:

component (2) is an alkylphenol sulfide (“APS”);

component (3) is an alkyl phosphate phenate sulfide (“APPS”);

component (4) is a polyalkylene succinimide (“PAS”); and

component (5) is a polyalkylene thiophosphonic acid ester (“PETPA”).