Method of Upgrading a Heavy Oil Feedstock

Abstract

A pretreatment process is described for heavy hydrocarbon oil feedstock, such as oils extracted from tar sands. The feedstock is passed through a heated, continuous flow electron or x-ray treatment zone. The process is designed to allow the feedstock to be conditioned with ozone-containing air, steam or a hydrogen donor gas prior to electron/x-ray treatment. The ozone-containing air stream may be the stream produced in the electron treatment zone. After conditioning, the heavy oil is heated to a specified temperature and uniformly treated with high-energy beams of electrons or x-rays. A key feature of the invention is the electron/x-ray treatment zone may use multiple accelerators or a beam splitter to ensure acceptable dose distributions in the flowing feedstock. Another key feature is the recirculation of volatiles back into the feedstock. According to the novel feature, the process produces a treated feedstock having a lower average molecular weight and boiling point than the original feedstock, without significant coke formation. The fraction of gas oil collected during distillation is increased significantly.

1 . A method of upgrading a heavy oil feedstock, the method comprising:
 forming a continuous flow of the heavy oil feedstock;   heating the continuous flow to a prescribed temperature;   cracking the heavy oil feedstock in the continuous flow by directing either electrons or x-rays at the continuous flow.   
   
   
       2 . The method according to  claim 1  including recycling a separated portion comprising volatized parts of the continuous flow back into the continuous flow prior to electron cracking. 
   
   
       3 . The method according to  claim 1  including varying constituents of the continuous flow subsequent to cracking by varying an amount of the separated portion recycled back into the continuous flow. 
   
   
       4 . The method according to  claim 1  including recycling back into the flow a separated portion comprising a part of the continuous flow which is volatized when heating the flow to said prescribed temperature. 
   
   
       5 . The method according to  claim 1  including preconditioning the continuous flow prior to heating to said prescribed temperature by adding to the flow a selected one or more of ozone, steam or a hydrogen donor gas and recycling back into the flow a separated portion comprising parts of the continuous flow which are volatized when preconditioning. 
   
   
       6 . The method according to  claim 1  including reducing a cross sectional dimension of the continuous flow in one direction prior to electron cracking. 
   
   
       7 . The method according to  claim 1  including recycling back into the flow a separated portion of the continuous flow comprising hydrocarbon molecules. 
   
   
       8 . The method according to  claim 1  including electron or x-ray cracking at conditions near atmospheric pressure. 
   
   
       9 . The method according to  claim 1  including mixing the continuous flow during electron or x-ray cracking. 
   
   
       10 . The method according to  claim 1  including directing electrons at the continuous flow from more than one direction. 
   
   
       11 . A method according to  claim 1  including arranging a portion of the continuous flow to comprise hydrocarbons having a boiling point lower than said prescribed temperature prior to electron or x-ray cracking by maintaining under pressure in the continuous flow at least a portion of hydrocarbons volatized during heating.