Process for thermal cracking of residual oils

Claim 2

A process for the thermal cracking of an extraction residue from a solvent deasphalting process, which comprises: providing said extraction residue by solvent extraction of a petroleum hydrocarbon residual oil with a solvent selected from the group consisting of butane, pentane, hexane, and mixtures thereof under conditions such that the extraction residue contains at least about 40% asphaltenes or pentane-insolubles, and subjecting said extraction residue to thermal cracking by a method consisting essentially of the following steps: (a) commingling said extraction residue with a carrier gas; (b) passing the resultant fluid mixture through a tubular thermal cracking zone at thermal cracking conditions, including a temperature of from about 400° C. to about 600° C. and a residence time not more than about 8 minutes to effect thermal cracking of said extraction residue; (c) regulating the amount of said carrier gas to provide a flow velocity of said fluid mixture at the inlet of said tubular thermal cracking zone of from about 0.5 to about 4.0 m/sec, providing heat input to said tubular thermal cracking zone such that the heat flux is from about 5,000 to about 40,000 kcal/m 2 hr, and maintaining a temperature difference between the outside surface of said tubular thermal cracking zone and the fluid mixture flowing therethrough of less than about 100° C., whereby to minimize or avoid coking in said cracking zone; and (d) separating and recovering cracked oil and pitch from the effluent reaction products from said thermal cracking zone, the wt.% yield of cracked oil being substantially less than the wt.% yield of pitch.

Claim 3

The process of claim 1 wherein said extraction residue contains from about 60% to about 80% asphaltene or pentane-insolubles.

Claim 4

The process of claim 1 wherein said extraction residue is mixed with an additive oil to adjust its viscosity and improve its fluidity.

Claim 5

The process of claim 3 wherein said additive oil is gas oil or cracked oil.

Claim 6

The process of claim 1 wherein said flow velocity is from about 1.5 to about 2.0 m/sec.

Claim 7

The process of claim 1 wherein said heat flux is from about 10,000 to about 20,000 kcal/m 2 hr and said temperature difference is not more than about 20° C.

Claim 8

The process of claim 1 wherein said thermal cracking conditions are controlled so that the yield of said cracked oil is not more than about 30 to 35%.

Claim 9

The process of claim 1 wherein said carrier gas comprises a substantially inert gas.

Claim 10

The process of claim 1 wherein said carrier gas is selected from the group consisting of nitrogen, steam, cracked gas, and mixtures thereof.

Claim 11

The process of claim 1 wherein said carrier gas comprises hydrogen or a hydrogen-containing gas whereby desulfurization and hydrocracking or hydroreforming reactions also occur in said thermal cracking zone.

Claim 12

The process of claim 1 wherein said carrier gas is preheated to a temperature of from about 100° C. to about 400° C.

Claim 13

The process of claim 4 wherein the amount of said gas oil or cracked oil is not more than about 30% by weight of the mixture.

Claim 14

The process of claim 7 wherein said pitch has a toluene-insoluble content of about 30% or less whereby to facilitate gravity withdrawal of said pitch from a separation vessel that receives the effluent reaction products from said thermal cracking zone.

Claim 15

A process for the thermal cracking of an extraction residue from a solvent deasphalting process, which comprises: providing said extraction residue by solvent extraction of a petroleum hydrocarbon residual oil with a solvent selected from the group consisting of butane, pentane, hexane, and mixtures thereof under conditions such that the extraction residue contains from about 60% to about 80% asphaltenes or pentane-insolubles, and subjecting said extraction residue to thermal cracking by a method consisting essentially of the following steps: (a) mixing said extraction residue with an additive oil in an amount not more than about 30% by weight of the mixture to improve the fluidity of the extraction residue; (b) commingling the mixture of extraction residue and additive oil with a carrier gas; (c) passing the resultant fluid mixture through a tubular thermal cracking zone at thermal cracking conditions, including a temperature of from about 400° C. to about 600° C. and a residence time not more than about 8 minutes to effect thermal cracking of said extraction residue to cracked oil and pitch; (d) controlling said thermal cracking conditions so that the yield of said cracked oil is not more than about 30 to 35% and said pitch has a toluene insoluble content of about 30% or less; (e) regulating the amount of said carrier gas to provide a flow velocity of said fluid mixture at the inlet of said tubular thermal cracking zone of from about 0.5 to about 4.0 m/sec, regulating the heat input to said tubular thermal cracking zone so that the heat flux is from about5,000 to about 40,000 kcal/m 2 hr, and maintaining a temperature difference between the outside surface of said tubular thermal cracking zone and the fluid mixture flowing therethrough of less than about 100° C., whereby to minimize or avoid coking in said cracking zone; and (f) separating and recovering cracked oil and pitch from the effluent reaction products from said thermal cracking zone, the wt.% yield of cracked oil being substantially less than the wt.% yield of pitch.

Claim 16

A process for the thermal cracking of an extraction residue from a solvent deasphalting process, which comprises: providing said extraction residue by solvent extraction of a petroleum hydrocarbon residual oil with a solvent selected from the group consisting of butane, pentane, hexane, and mixtures thereof under conditions such that the extraction residue contains from about 60% to about 80% asphaltenes or pentane-insolubles, and subjecting said extraction residue to thermal cracking by a method consisting essentially of the following steps: (a) mixing said extraction residue with an additive oil in an amount not more than about 30% by weight of the mixture to improve the fluidity of the extraction residue; (b) commingling the mixture of extraction residue and additive oil with a carrier gas; (c) passing the resultant fluid mixture through a tubular thermal cracking zone at thermal cracking conditions, including a temperature of from about 400° C. to about 600° C. and a residence time not more than about 8 minutes to effect thermal cracking of said extraction residue to cracked oil and pitch; (d) controlling said thermal cracking conditions so that the yield of said cracked oil is not more than about 30 to 35% and said pitch has a toluene insoluble content of about 30% or less; (e) regulating the amount of said carrier gas to provide a flow velocity of said fluid mixture at the inlet of said tubular thermal cracking zone of from about 0.5 to about 4.0 m/sec, regulating the heat input to said tubular thermal cracking zone so that the heat flux is from about5,000 to about 40,000 kcal/m 2 hr, and maintaining a temperature difference between the outside surface of said tubular thermal cracking zone and the fluid mixture flowing therethrough of less than about 100° C., whereby to minimize or avoid coking in said cracking zone; and (f) separating and recovering cracked oil and pitch from the effluent reaction products from said thermal cracking zone, the wt.% yield of cracked oil being substantially less than the wt.% yield of pitch.