OVERVIEW

In every chapter of this book, the reference was made to the non-catalytic processes used for the upgrading heavy petroleum feeds. In this case, the VRs, particularly those obtained from the most problematic heavy crudes were the feeds of the primary interest. The carbon rejection from such feeds can be achieved either thermally or via deasphalting. The detailed review of these processes is out of the scope of this book. It is, however, believed that a cursory account of these processes may aid readers in identifying the essential factors and/or reasons for selecting non-catalytic route over catalytic upgrading such as hydroprocessing. It has been indicated that there is a limit on the metals and asphaltenes contents above which the catalytic upgrading of heavy feeds becomes economically unattractive. Thus, above such limit, the costs of the catalyst inventory cannot be offset by the increased yields of liquid products obtained using the hydrogen addition processes compared with that obtained from the carbon-rejection processes.

The scale of the operation is an important factor which has to be considered while comparing the hydroprocessing processes with the carbon rejection-processes. For the most problematic heavy feeds, practical experience suggests that the carbon-rejecting processes have been the processes of choice for large scale operations, e.g., more than 100 000 lbb/d upgrading. However, in the case of the Syncrude plant in Canada, the EXXON fluid-coking process comprising two coker-burner assemblies has been operating in parallel with two ebullated bed reactor systems with the daily production of more...