Reduction of distillation unit fouling

Abstract

Basic components, including nitrogenous compounds, which lead to fouling in the overhead of petroleum refinery processing units, especially the crude unit, are removed by adsorbing the basic compounds on an adsorbent with acidic functionality. Suitable adsorbents include acidic functioning zeolites, ion-exchange resins and acidic amorphous solids such as alumina and solid acids such as solid phosphoric acid, tungstic acid and similarly functioning materials. The removal is typically affected by contacting a reflux stream from the distillation or other unit with a bed of the adsorbent.

What is claimed: 
     
         1 . A method of reducing fouling in a petroleum refinery process unit in which basic nitrogen compounds are present in a circulating stream of petroleum hydrocarbons, which method comprises passing the stream in contact with a solid, porous adsorbent having acidic functionality to adsorb the basic nitrogen compounds on the adsorbent. 
     
     
         2 . A method according to  claim 1  in which the basic nitrogen compounds are adsorbed on the adsorbent by reaction with acidic sites on the adsorbent. 
     
     
         3 . A method according to  claim 1  in which the solid adsorbent comprises a porous, acidic metal oxide. 
     
     
         4 . A method according to  claim 1  in which the solid adsorbent comprises an amorphous, acidic metal oxide. 
     
     
         5 . A method according to  claim 1  in which the solid adsorbent comprises a porous, acidic crystalline zeolite. 
     
     
         6 . A method according to  claim 1  in which the solid adsorbent comprises a porous, acidic cation exchange resin. 
     
     
         7 . A method according to  claim 1  in which the stream of petroleum hydrocarbons is circulating in a recirculation loop of a refinery unit operating at elevated temperature. 
     
     
         8 . A method according to  claim 1  in which the stream of petroleum hydrocarbons is circulating in a reflux loop of a distillation unit. 
     
     
         9 . A method according to  claim 1  in which the stream of petroleum hydrocarbons is circulating in a reflux loop of a crude oil atmospheric distillation unit. 
     
     
         10 . A method according to  claim 1  in which the stream of petroleum hydrocarbons is circulating in a reflux loop of a crude oil atmospheric distillation unit and is contacted with the solid, porous adsorbent in the reflux loop. 
     
     
         11 . A method of reducing fouling in a low temperature end of a petroleum refinery distillation tower having a low temperature end and a high temperature end in which basic nitrogen compounds are present in a circulating reflux stream of petroleum hydrocarbons at the low temperature end, which method comprises passing the circulating reflux stream in contact with a solid, porous adsorbent having acidic functionality to adsorb the basic nitrogen compounds on the adsorbent. 
     
     
         12 . A method according to  claim 11  in which the circulating reflux stream of petroleum hydrocarbons is circulating in a reflux loop of a crude oil atmospheric distillation unit. 
     
     
         13 . A method according to  claim 12  in which the stream of petroleum hydrocarbons is circulating in the reflux loop of the crude oil atmospheric distillation unit and is contacted with the solid, porous adsorbent in the reflux loop. 
     
     
         14 . A method according to  claim 13  in which the stream of petroleum hydrocarbons is circulating in the reflux loop of the crude oil atmospheric distillation unit comprising a cooler connected to the low temperature end of the tower, a receiver to receive a cooled stream from the cooler and a bed of solid, porous adsorbent located in the reflux loop between the receiver and the tower. 
     
     
         15 . A method according to  claim 13  in which the reflux loop includes means for adding a corrosion-inhibiting basic nitrogenous compound to the circulating reflux stream. 
     
     
         16 . A method according to  claim 13  in which the reflux loop includes means for adding a corrosion-inhibiting basic nitrogenous compound to the circulating reflux stream between the low temperature end of the tower and the receiver. 
     
     
         17 . A method according to  claim 11  in which the stream of petroleum hydrocarbons is circulating in the reflux loop of a crude oil atmospheric distillation unit. 
     
     
         18 . A method according to  claim 11  in which the stream of petroleum hydrocarbons is circulating in the reflux loop of a vacuum distillation unit.