Process and facility for treatment of crude oil with asphaltenic residue conversion
A process for refining or pre-refining a crude oil P is described in which P is fractionated into several fractions, wherein partial oxidation of an asphaltenic residue R1 derived from P is carried out to produce a synthesis gas SG1 with an H 2 /CO ratio of less than 1, steam cracking is carried out of an external light hydrocarbon fraction to produce a synthesis gas SG2 with a H 2 /CO ratio of more than 3; SG1 and SG2 are mixed to produce a synthesis gas SG with a H 2 /CO ratio in the range 1.2 to 2.5, and SG is converted by Fischer-Tropsch synthesis, then the waxes produced are converted into middle distillates. Preferably, a vacuum distillate VGO and/or a deasphalted oil DAO derived from P are hydrocracked mixed with the waxes. The invention also pertains to a facility for carrying out the process.
1. A process for transforming at least one crude oil P, comprising;
a preliminary treatment of P, comprising fractionating P by distillation (PRE-DIST) and/or deasphalting (SDA) to produce asphalt AS and at least one first non-asphaltenie stream E1 boiling essentially above 340° C.;
partially oxidizing (POX) the asphalt AS supplemented with 4% to 40% by weight of desalted oil P to produce a first synthesis gas SG1 with a H 2 /CO ratio of less than 1;
steam reforming a cut G comprising hydrocarbons containing less than 5 carbon atoms, said hydrocarbons comprising C1-C4 fractions recycled from a Fischer-Tropsch conversion step and a hydrocracking step, wherein at least 50% by weight of said hydrocarbons are external to the crude oil P, to produce a second synthesis gas SG2 with a H 2 /CO ratio of more than 3;
mixing at least a portion of SG1 and at least a portion of SG2 in a proportion which can produce a synthesis gas SG with a H 2 /CO ratio in the range 1.2 to 2.5;
Fischer-Tropsch converting SG, generally purified by preliminary purification (PUR-FT), to obtain principally liquid fractions and paraffin waxes;
hydrocracking (HDK) at least the major portion of said paraffin waxes to produce at least one cut comprising liquid hydrocarbons boiling below 340° C., which hydrocracking is carried out on at least the majority of the paraffin waxes mixed with E1;
and producing at least one pre-refined non-asphaltenic oil Pa from at least a portion of the non-asphaltenic cuts derived from the preliminary treatment of P, optionally after catalytic hydrogenating treatment(s), and from at least a portion of the hydrocracking effluents.
2. A process according to claim 1 , in which E1 is essentially constituted by vacuum distillate VGO and/or deasphalted oil DAO.
3. A process according to claim 1 , in which hydrogen used for hydrocracking is produced from a fraction of the steam reforming effluents.