Production of substantially free-flowing coke from a deeper cut of vacuum resid in delayed coking

Abstract

A modified vacuum distillation and delayed coking process for making substantially free-flowing coke, preferably free-flowing shot coke. A vacuum resid feedstock is used which contains less than about 10 wt. % material boiling between 900° F. and 1040° F. as determined by HTSD (High-temperature Simulated Distillation). The use of such a high boiling resid favors the formation of shot coke instead of sponge or transition coke. The distillate recycle reduces coker furnace fouling potential of the heavier feedstock.

1 . A delayed coking process comprising: 
 preparing a vacuum resid that has less than 10 wt. % 900° F. to 1040° F. boiling material as measured by HTSD (High-Temperature Simulated Distillation) and combining with a distillate recycle stream wherein the distillate recycle stream has boiling range within the interval of about 450° F. to about 750° F.;    conducting said mixture to a heating zone wherein it is heated to an effective coking temperature; and    conducting said heated mixture from said heating zone to a coking zone wherein vapor products are collected overhead and whereby coke with reduced incidence of hot drums and of a relatively free-flowing nature is formed.    
   
   
       2 . The process of  claim 1  wherein a substantially free-flowing shot coke product is produced.  
   
   
       3 . The process of  claim 1  wherein an additive is introduced into the feedstock either prior to heating or just prior to it being introduced in the coker vessel, which additive is an organic soluble, organic insoluble, or non-organic miscible metals-containing additive that is effective for the formation of substantially free-flowing coke.  
   
   
       4 . The process of  claim 3  wherein the metal of the additive is selected from the group consisting of potassium, sodium, iron, nickel, vanadium, tin, molybdenum, manganese, cobalt, calcium, magnesium, aluminum and mixtures thereof.  
   
   
       5 . The delayed coking process of  claim 1  wherein the distillate recycle is in the range of about 1 to 20 volume percent.  
   
   
       6 . The delayed coking process of  claim 5  wherein the distillate recycle is in the range of about 0 to 7 volume percent.  
   
   
       7 . The delayed coking process of  claim 5  wherein the distillation recycle is in the range of about 0 to 3.5 volume percent.  
   
   
       8 . The process of  claim 1  which is run with manual or automated slide valves at the bottom of the drum.  
   
   
       9 . The process of  claim 5  run with manual or automated slide valves at the bottom of the coke drum