METHOD FOR CONTROLLING A PRETREATMENT PROCESS

An improved process is provided for decarbonizing, demetallizing and/or desalting a hydrocarbon feed stock by: contacting, in a selective vaporization step, for a short hydrocarbon residence time at an elevated contact temperature, the feed stock with an inert solid contact material in a confined rising vertical column to vaporize a major portion of the feed stock and to provide, as combustible deposits on the contact material, an unvaporized minor portion of the feed stock which includes high Conradson Carbon components and/or metal-containing components of the feed stock; separating the vaporized major portion of the feed stock from the contact material bearing the combustible deposits; contacting in a combustion step the contact material, bearing the combustible deposits, with an oxidizing gas to oxidize the combustible deposits and generate heat, whereby the contact material is heated by combustion of the combustible deposits; and recycling the so-heated contact material to contact further feed stock in the selective vaporization step. The improvement in the process comprises: contacting the contact material in the combustion step with less than the stoichiometric amount of oxidizing gas, required to oxidize completely the combustible deposits, so that oxidizable high Conradson Carbon and/or metal-containing components of the combustible deposits are only partially oxidized to carbon monoxide and so that there is a reducing atmosphere in the combustion step.