Additives for reducing coking of furnace tubes

Abstract

Fouling of hot furnace surfaces in selected refinery processes can be stopped or at least mitigated using an antifouling agent. The antifouling agents include sulfurized oil and may include other components selected from the group consisting of magnesium and aluminum overbases, a-olefin copolymers, and combinations thereof. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b)

1 . A process for reducing furnace fouling comprising treating a furnace feed stream with an antifouling agent wherein the antifouling agent comprises sulfurized oil. 
     
     
         2 . The process of  claim 1  wherein the sulfurized oil is prepared using a process comprising the steps of:
 mixing a mole ratio of a polyolefin to sulfur of between about 1:2.5 and about 1:5 at between about 50 and about 100° F.; 
 continuously blowing the resultant mixture with an inert gas under continuous pressure and under elevated temperatures until the free sulfur weight in the said resultant reaction mixture is less than about 0.3 weight percent; 
 stripping the blown mixture with inert gas at an elevated temperature at sub-atmospheric pressure; and 
 filtering the stripped product. 
 
     
     
         3 . The process of  claim 2  wherein the polyolefin is triisobutylene. 
     
     
         4 . The process of  claim 1  wherein the sulfurized oil is selected from the group consisting of sulfurized lard, sulfurized fish oil, sulfurized whale oil, sulfurized soybean oil, sulfurized pinene oil, sulfurized sperm oil, sulfurized fatty acid, 1,3,4-thiadiazol derivatives, thiuram disulfide, dithiocarbamate ester, and combinations thereof. 
     
     
         5 . The process of  claim 1  wherein the sulfurized oil has the general formula:
   R—S X —R
 
 
       wherein: X is 1 or 2, and each R is independently an alkyl group, a cyclic alkyl group, an olefin group, or a polyolefin group. 
     
     
         6 . The process of  claim 1  wherein the antifouling agent additionally comprises an overbase selected from the group consisting of magnesium overbases, aluminum overbases, and combinations thereof. 
     
     
         7 . The process of  claim 6  wherein the magnesium and/or aluminum content of the overbase is at least about 1 weight percent. 
     
     
         8 . The process of  claim 7  wherein the magnesium and/or aluminum content of the overbase is at least about 5 weight percent. 
     
     
         9 . The process of  claim 6  wherein the overbase is prepared with a complexing agent selected from the group consisting of carboxylic acids, phenols, organic phosphorus acids, organic sulfur acids, and combinations thereof. 
     
     
         10 . The process of  claim 1  wherein the antifouling agent additionally comprises a dispersant. 
     
     
         11 . The process of  claim 10  wherein the dispersant is a copolymer of a carboxylic anhydride and an alpha-olefin. 
     
     
         12 . The process of  claim 11  wherein the alpha-olefin has from about 2 to about 70 carbon atoms. 
     
     
         13 . The process of  claim 11  wherein the carboxylic anhydride is selected from the group consisting of: maleic anhydride, succinic anhydride, glutaric anhydride, tetrapropylene succinic anhydride, phthalic anhydride, trimellitic anhydride (oil soluble, non-basic), and mixtures thereof. 
     
     
         14 . The process of  claim 1  wherein the antifouling agent includes at least one other component selected from the group consisting of a magnesium and/or aluminum overbase, a dispersant, and combinations thereof, and the weight ratio of sulfurized oil to the other component or components is from about 10:1 to about 1:10. 
     
     
         15 . The process of  claim 14  wherein the weight ratio of sulfurized oil to the other component or components is from about 3:1 to about 1:3. 
     
     
         16 . The process of  claim 15  wherein the weight ratio of sulfurized oil to the other component or components is about 1:1. 
     
     
         17 . The process of  claim 1  wherein the furnace feed stream is a partial or full feed stream selected from the group of feed streams consisting of a coking process feed stream, a visbreaking process feed stream, and a vacuum distillation process feed stream. 
     
     
         18 . The process of  claim 1  wherein the antifouling agent is present in the feed stream at a concentration of from about 50 ppm by weight to about 10,000 ppm by weight. 
     
     
         19 . A process for reducing furnace fouling comprising treating a furnace feed stream with an antifouling agent wherein the antifouling agent comprises sulfurized oil and an overbase selected from the group consisting of magnesium overbases, aluminum overbases, and combinations thereof. 
     
     
         20 . A composition comprising a hydrocarbon feed stream for a coking or visbreaking process and an additive comprising sulfurized oil.