Selective vaporization process and dynamic control thereof

In a process for decarbonizing or demetallizing a hydrocarbon charge of whole crude or a residual fraction thereof by contacting said charge in a confined rising vertical column with a finely divided solid contact material consisting essentially of an inert solid material having a microactivity for catalytic cracking not substantially greater than 20 at low severity, including a temperature of at least about 900.degree. F. for a period of time less than about 3 seconds and less than that which induces substantial thermal cracking in said charge, at the end of said period of time separating a selectively vaporized major portion of said charge from said contact material bearing the unvaporized portion of the charge as deposit thereon, contacting said contact material bearing said deposit in a combustion zone with oxidizing gas to burn said deposit and generate heat whereby the temperature of said contact material is elevated by combustion of said unvaporized portion of the charge as fuel for the process, recycling the so heated contact material to renewed contact with said hydrocarbon charge, the improvement which comprises sensing the temperature of said confined column, regulating the rate of recycling said so heated contact material responsive to the temperature so sensed to maintain said sensed confined column temperature at a predetermined value and dynamically controlling the system for the purpose of utilizing low hydrogen content, low value portions of said charge as said fuel for the process which dynamic control comprises adjusting said predetermined value of said sensed confined column temperature to about the minimum level at which said deposit provides the quantity of fuel which will, on combustion, maintain said combustion zone at a predetermined temperature;

• said adjustment being effected (a) by reducing said predetermined temperature of said rising confined column to provide more fuel in order to correct a trend toward lower temperature in said combustion zone or (b) by increasing said predetermined temperature of said rising confined column to provide less fuel in order to correct a trend toward higher temperature in said combustion zone.