Abstract: Disclosed herein are systems and methods for monitoring and controlling a nitroxide-based polymerization inhibitor in vinyl-based monomers. A dosage of the nitroxide-based polymerization inhibitor is provided in the vinyl-based monomers. A residual concentration of the nitroxide-based polymerization inhibitor is measured substantially in real time, and an optimized dosage of the nitroxide-based polymerization inhibitor is provided in response to the measured residual concentration.

Abstract: Disclosed herein are systems and methods for monitoring and controlling a nitroxide-based polymerization inhibitor in vinyl-based monomers. A dosage of the nitroxide-based polymerization inhibitor is provided in the vinyl-based monomers. A residual concentration of the nitroxide-based polymerization inhibitor is measured substantially in real time, and an optimized dosage of the nitroxide-based polymerization inhibitor is provided in response to the measured residual concentration.

Abstract: The invention provides a composition of matter and a method of its use in preventing unwanted polymerization reactions. The composition comprises an inhibitor and a retarder. The inhibitor is highly effective. The retarder is reliable under extreme and emergency situations. The inhibitor can be an alkylhydroxylamine. The retarder can be a 7-cyano-quinone methide. The combination of the inhibitor and retarder has been found to be far more effective than expected.

Abstract: A method for improving purification efficiency when distilling off aldehyde contaminants during chemical manufacturing processes by adding a substituted aromatic amine having electron donating group substituents prior to the distillation column. The method is particularly useful for removal of aldehydes such as acrolein, generated as a by-product of acrylonitrile manufacture. Preferred aromatic amines are 2-amino aniline, 3,4-dimethyl aniline and 4-ethyl aniline.

Abstract: Polymerization is inhibited during the anaeroic production of styrene through the addition of a combination of a stable nitroxide free radical compound and a non-toxic phenylenediamine compound.

Abstract: Inhibition performance is improved in styrene processing through the addition of a stable nitroxide free radical compound to the styrene feed and to the reflux of at least one column.

Abstract: A method of inhibiting the formation of fouling deposits occurring in spent caustic wash systems used for ethylene dichloride (EDC) manufacturing processes. Fouling occurs in these systems when they are in contact with EDC processing streams contaminated with oxygen-containing compounds, such as aldehydes. These deposits are formed in EDC processing streams contaminated with oxygen-containing compounds while in contact with a caustic solution having a pH>7. The invention comprises adding an effective deposit-inhibiting amount of a non-enolizable carbonyl compound to the caustic solution. Preferred non-enolizable carbonyl compounds are formaldehyde, glyoxal, benzaldehyde, p-anisaldehyde, formic acid, glyoxalic acid and paraformaldehyde.

Abstract: The invention is a method of inhibiting the formation of fouling deposits occurring on the surface of an alkaline scrubber used to remove acid gases, such as hydrogen sulfide, carbon dioxide and mercaptans, from hydrocarbon streams. These deposits are formed during the scrubbing of pyrolytically produced hydrocarbons contaminated with oxygen-containing compounds with a caustic solution having a pH>7 which comprises adding an effective deposit-inhibiting amount of a non-enolizable carbonyl compound to the caustic solution. The invention is also a method of inhibiting the formation of fouling deposits occurring in spent caustic wash/stripper systems used for hydrocarbon manufacturing processes. Fouling occurs in these systems when they are in contact with hydrocarbon processing streams contaminated with oxygen-containing compounds, such as aldehydes.

Abstract: A method of inhibiting the formation of fouling deposits occurring on the surfaces of an alkaline scrubber used to wash acid gases generated during the manufacture of olefins, which deposits are formed during the scrubbing of pyrolytically produced hydrocarbons contaminated with oxygen-containing compounds with a caustic solution having a pH>7, which comprises adding an effective depositing-inhibiting amount of a caustic solution-soluble substituted aromatic amine selected from the group consisting of: 2-aminophenol, 4-aminophenol, 4-aminobenzenesulfonic acid and salts thereof, 4-amino-o-cresol, 3-aminophenol, 2-aminobenzoic acid and salts thereof, 3-aminobenzoic acid and salts thereof, and 4-aminobenzoic acid and salts thereof to the caustic solution. A preferred substituted aromatic amine is the sodium salt of 4-amino- benzenesulfonic acid in aqueous solution.

Abstract: The invention provides a method for the inhibition of fouling in petrochemical processes. The method comprises adding from about 0.1 to about 10,000 parts per million sulfonated oils, sulfonated fatty acids, sulfated oils, sulfated fatty acids, or naphthalene sulfonate formaldehyde condensates to a petrochemical process to disperse water insoluble foulant into an aqueous system.

Abstract: A process for breaking the emulsion which commonly forms in the caustic system of olefin plants comprising mixing the emulsion with an effective amount of a Group II metal salt of an alkyl aryl sulfonic acid, wherein the alkyl contains 4-24 carbon atoms, most preferably 8-14 carbon atoms.

Abstract: An improved process for inhibiting the formation and deposition of polymer-based fouling materials after caustic scrubbing of hydrocarbon streams contaminated with oxygenated compounds with a basic washing solution having a pH>7 comprising adding to the hydrocarbon stream after caustic scrubbing a sufficient amount for inhibiting formation and deposition of polymer-based fouling materials of a composition comprising at least one hydrazide compound characterized by the formula ##STR1## where R is selected from the group consisting of H, NHNH.sub.

Abstract: In a method for reducing the fouling of a compressor of a vinyl acetate production unit having a light ends stream feed, a hindered phenol is added to the compressor feed. The method retards the loss of compressor efficiency with run time and increases the run time before clean-out is required. The hindered phenol is added in a dosage amount effective for reducing the fouling of the compressor.

Abstract: Generally, the invention provides a fouling probe apparatus. The fouling probe including a heat transfer conduit having a first portion formed as a loop which is removably attached to a second portion which extends linearly. A hollow housing encases the apparatus. The housing has an open forward portion and an open rear portion. The open forward portion is attachable to an oil quench tower about an opening in the quench tower and the open rear portion is adapted to be securely attached to the linearly extending second portion of the heat transfer conduit. A fouling grid is attached to the first portion of the heat transfer conduit. The fouling grid is super-heated to accelerate fouling.

Abstract: A method for inhibiting the formation of fouling materials during the caustic washing of hydrocarbons contaminated with oxygen compounds is disclosed. The method comprises adding an effective amount of carbohydrazide to the caustic wash system.

Abstract: Polymerization of aromatic, ethylenically unsaturated monomers, such as styrene, is inhibited by adding alkyl phenol sulfonic acids.